DISPLAY DEVICE, DISPLAY MODULE, ELECTRONIC DEVICE, AND METHOD OF MANUFACTURING DISPLAY DEVICE

A highly reliable display device is provided. The display device includes a first light-emitting element, a second light-emitting element adjacent to the first light-emitting element, a first insulating layer provided between the first light-emitting element and the second light-emitting element, and a second insulating layer over the first insulating layer. The first light-emitting element includes a first conductive layer, a second conductive layer covering an upper surface and a side surface of the first conductive layer, a first EL layer covering an upper surface and a side surface of the second conductive layer, and a common electrode over the first EL layer. The second light-emitting element includes a third conductive layer, a fourth conductive layer covering an upper surface and a side surface of the third conductive layer, a second EL layer covering an upper surface and a side surface of the fourth conductive layer, and the common electrode over the second EL layer. The common electrode is provided over the second insulating layer. The visible light reflectance of the first conductive layer is higher than the visible light reflectance of the second conductive layer. The visible light reflectance of the third conductive layer is higher than the visible light reflectance of the fourth conductive layer.

TECHNICAL FIELD

One embodiment of the present invention relates to a display device, a display module, and an electronic device. One embodiment of the present invention relates to a method of manufacturing a display device.

Note that one embodiment of the present invention is not limited to the above technical field. Examples of the technical field of one embodiment of the present invention include a semiconductor device, a display device, a light-emitting apparatus, a power storage device, a memory device, an electronic device, a lighting device, an input device (e.g., a touch sensor), an input/output device (e.g., a touch panel), a method for driving any of them, and a method of manufacturing any of them.

BACKGROUND ART

Recent display devices have been expected to be applied to a variety of uses. Usage examples of large-sized display devices include a television device for home use (also referred to as TV or television receiver), digital signage, and a PID (Public Information Display). In addition, a smartphone and a tablet terminal each including a touch panel, and the like, are being developed as portable information terminals.

Furthermore, higher-resolution display devices have been required. As devices requiring high-resolution display devices, for example, devices for virtual reality (VR), augmented reality (AR), substitutional reality (SR), or mixed reality (MR) have been actively developed.

Light-emitting apparatuses including light-emitting elements (also referred to as light-emitting devices) have been developed as display devices, for example. Light-emitting devices (also referred to as EL elements or organic EL elements) utilizing electroluminescence (EL) have features such as ease of reduction in thickness and weight, high-speed response to input signals, and driving with a constant DC voltage power source, and have been used in display devices.

Patent Document 1 discloses a display device using an organic EL element (also referred to as an organic EL device) for VR.

Non-Patent Document 1 discloses a method of manufacturing an organic optoelectronic device using standard UV photolithography.

References

Patent Document

SUMMARY OF THE INVENTION

Problems to be Solved by the Invention

An organic EL element can have a structure in which a layer containing an organic compound is interposed between a pair of electrodes, for example. Here, in the case of having a stacked-layer structure of a plurality of layers containing different materials, an electrode might change in quality as a result of, for example, a reaction occurring between the plurality of layers. This degrades the reliability of the display device in some cases.

In view of the above, an object of one embodiment of the present invention is to provide a highly reliable display device. Another object of one embodiment of the present invention is to provide a display device including a light-emitting element with high emission efficiency. Another object of one embodiment of the present invention is to provide a display device having low power consumption. Another object of one embodiment of the present invention is to provide a display device with high light extraction efficiency. Another object of one embodiment of the present invention is to provide an inexpensive display device. Another object of one embodiment of the present invention is to provide a display device with high display quality. Another object of one embodiment of the present invention is to provide a high-resolution display device. Another object of one embodiment of the present invention is to provide a high-definition display device. Another object of one embodiment of the present invention is to provide a novel display device.

Another object of one embodiment of the present invention is to provide a method of manufacturing a display device with high yield. An object of one embodiment of the present invention is to provide a method of manufacturing a highly reliable display device. Another object of one embodiment of the present invention is to provide a method of manufacturing a display device including a light-emitting element with high light extraction efficiency. Another object of one embodiment of the present invention is to provide a method of manufacturing a display device with low power consumption. Another object of one embodiment of the present invention is to provide a method of manufacturing a display device with high light extraction efficiency. An object of one embodiment of the present invention is to provide a method of manufacturing a display device with high display quality. Another object of one embodiment of the present invention is to provide a method of manufacturing a high-resolution display device. Another object of one embodiment of the present invention is to provide a method of manufacturing a high-definition display device. Another object of one embodiment of the present invention is to provide a method of manufacturing a novel display device.

Note that the description of these objects does not preclude the existence of other objects. One embodiment of the present invention does not need to achieve all of these objects. Other objects can be derived from the description of the specification, the drawings, and the claims.

Means for Solving the Problems

One embodiment of the present invention is a display device including a first light-emitting element, a second light-emitting element adjacent to the first light-emitting element, a first insulating layer provided between the first light-emitting element and the second light-emitting element, and a second insulating layer over the first insulating layer. The first light-emitting element includes a first conductive layer, a second conductive layer covering an upper surface and a side surface of the first conductive layer, a first EL layer over the second conductive layer, and a common electrode over the first EL layer. The second light-emitting element includes a third conductive layer, a fourth conductive layer covering an upper surface and a side surface of the third conductive layer, a second EL layer over the fourth conductive layer, and the common electrode over the second EL layer. The common electrode is provided over the second insulating layer. The visible light reflectance of the first conductive layer is higher than the visible light reflectance of the second conductive layer. The visible light reflectance of the third conductive layer is higher than the visible light reflectance of the fourth conductive layer.

Alternatively, in the above embodiment, the first EL layer may include a first functional layer including a region in contact with the second conductive layer and a first light-emitting layer over the first functional layer. The second EL layer may include a second functional layer including a region in contact with the fourth conductive layer and a second light-emitting layer over the second functional layer.

Alternatively, in the above embodiment, the first functional layer and the second functional layer may include at least one of a hole-injection layer and a hole-transport layer. The work function of the second conductive layer may be higher than the work function of the first conductive layer. The work function of the fourth conductive layer may be higher than the work function of the third conductive layer.

Alternatively, in the above embodiment, the first light-emitting element may include a common layer between the first EL layer and the common electrode. The second light-emitting element may include the common layer between the second EL layer and the common electrode. The common layer may be positioned between the second insulating layer and the common electrode. The common layer may include at least one of an electron-injection layer and an electron-transport layer.

Alternatively, in the above embodiment, the first functional layer and the second functional layer may include at least one of an electron-injection layer and an electron-transport layer. The work function of the second conductive layer may be lower than the work function of the first conductive layer. The work function of the fourth conductive layer may be lower than the work function of the third conductive layer.

Alternatively, in the above embodiment, the first light-emitting element may include a common layer between the first EL layer and the common electrode. The second light-emitting element may include the common layer between the second EL layer and the common electrode. The common layer may be positioned between the second insulating layer and the common electrode. The common layer may include at least one of a hole-injection layer and a hole-transport layer.

Alternatively, in the above embodiment, the second conductive layer and the fourth conductive layer may include any one or more selected from indium, tin, zinc, gallium, titanium, aluminum, and silicon.

Alternatively, in the above embodiment, the first insulating layer may include a region in contact with a side surface of the first EL layer and a side surface of the second EL layer and covers part of an upper surface of the first EL layer and part of an upper surface of the second EL layer. An end portion of the second insulating layer may have a tapered shape with a taper angle less than 90° in a cross-sectional view. The second insulating layer may cover at least part of a side surface of the first insulating layer.

Alternatively, in the above embodiment, an end portion of the first insulating layer may have a tapered shape with a taper angle less than 90° in a cross-sectional view.

Alternatively, in the above embodiment, the first insulating layer may be an inorganic insulating layer and the second insulating layer may be an organic insulating layer.

Alternatively, in the above embodiment, the first insulating layer may include aluminum oxide and the second insulating layer includes an acrylic resin.

A display module including the display device of one embodiment of the present invention and at least one of a connector and an integrated circuit is also one embodiment of the present invention.

An electronic device that includes the above display module and at least one of a housing, a battery, a camera, a speaker, and a microphone is also one embodiment of the present invention.

Another embodiment of the present invention is a method of manufacturing a display device, which includes: forming a first conductive layer: forming a second conductive layer that covers an upper surface and a side surface of the first conductive layer and has lower visible light reflectance than the first conductive layer: forming an EL film over the second conductive layer: forming a mask film over the EL film; and forming an EL layer over the second conductive layer and a mask layer over the EL layer by processing the EL film and the mask film.

Alternatively, in the above embodiment, hydrophobization treatment for the second conductive layer may be performed after the formation of the second conductive layer but before the formation of the EL film.

Alternatively, in the above embodiment, the hydrophobization treatment may be performed by fluorination of the second conductive layer.

Another embodiment of the present invention is a method of manufacturing a display device, which includes: forming a first conductive layer and a second conductive layer: forming a third conductive layer that covers an upper surface and a side surface of the first conductive layer and has lower visible light reflectance than the first conductive layer and a fourth conductive layer that covers an upper surface and a side surface of the second conductive layer and has lower visible light reflectance than the second conductive layer: forming a first EL film over the third conductive layer and over the fourth conductive layer: forming a first mask film over the first EL film: forming a first EL layer over the third conductive layer and a first mask layer over the first EL layer and exposing the fourth conductive layer by processing the first EL film and the first mask film: forming a second EL film over the first mask layer and over the fourth conductive layer: forming a second mask film over the second EL film: forming a second EL layer over the fourth conductive layer and a second mask layer over the second EL layer and exposing the first mask layer by processing the second EL film and the second mask film, forming an insulating film using a photosensitive material over the first mask layer and over the second mask layer: forming an insulating layer between the first EL layer and the second EL layer by processing the insulating film: exposing an upper surface of the first EL layer and an upper surface of the second EL layer by etching treatment using the insulating layer as a mask; and forming a common electrode over the first EL layer, over the second EL layer, and over the insulating layer.

Alternatively, in the above embodiment, hydrophobization treatment for the third conductive layer and the fourth conductive layer may be performed after the formation of the third conductive layer and the fourth conductive layer but before the formation of the first EL film.

Alternatively, in the above embodiment, the hydrophobization treatment may be performed by fluorination of the third conductive layer and the fourth conductive layer.

Alternatively, in the above embodiment, the etching treatment may be performed by wet etching.

Effect of the Invention

An embodiment of the present invention can provide a highly reliable display device. Another embodiment of the present invention can provide a display device including a light-emitting element with high emission efficiency. Another embodiment of the present invention can provide a display device having low power consumption. Another embodiment of the present invention can provide a display device with high light extraction efficiency. Another embodiment of the present invention can provide an inexpensive display device. Another embodiment of the present invention can provide a display device with high display quality. Another embodiment of the present invention can provide a high-resolution display device. Another embodiment of the present invention can provide a high-definition display device. Another embodiment of the present invention can provide a novel display device.

Another embodiment of the present invention can provide a method of manufacturing a display device with high yield. An embodiment of the present invention can provide a method of manufacturing a highly reliable display device. Another embodiment of the present invention can provide a method of manufacturing a display device including a light-emitting element with high light extraction efficiency. Another embodiment of the present invention can provide a method of manufacturing a display device with low power consumption. Another embodiment of the present invention can provide a method of manufacturing a display device with high light extraction efficiency. An embodiment of the present invention can provide a method of manufacturing a display device with high display quality. Another embodiment of the present invention can provide a method of manufacturing a high-resolution display device. Another embodiment of the present invention can provide a method of manufacturing a high-definition display device. Another embodiment of the present invention can provide a method of manufacturing a novel display device.

Note that the description of these effects does not preclude the existence of other effects. One embodiment of the present invention does not necessarily have all of these effects. Other effects can be derived from the description of the specification, the drawings, and the claims.

MODE FOR CARRYING OUT THE INVENTION

Note that in structures of the invention described below, the same reference numerals are commonly used for the same portions or portions having similar functions in different drawings, and a repeated description thereof is omitted. The same hatching pattern is applied to portions having similar functions, and the portions are not especially denoted by reference numerals in some cases.

The position, size, range, or the like of each component illustrated in drawings does not represent the actual position, size, range, or the like in some cases for easy understanding. Therefore, the disclosed invention is not necessarily limited to the position, size, range, or the like disclosed in drawings.

In this specification and the like, terms for describing positioning, such as “over,” “under,” “above,” and “below,” are sometimes used for convenience to describe the positional relation between components with reference to drawings. The positional relationship between components is changed as appropriate in accordance with a direction in which each component is described. Thus, the positional relation is not limited to the terms described in this specification and the like, and can be described with another term as appropriate depending on the situation. For example, the expression “an insulating layer positioned over (on) an upper surface of a conductive layer” can be replaced with the expression “an insulating layer positioned under (on) a lower surface of a conductive layer” when the direction of a drawing illustrating these components is rotated by 180°.

In this specification and the like, a device fabricated using a metal mask or an FMM (fine metal mask) is sometimes referred to as a device having an MM (metal mask) structure. In this specification and the like, a device fabricated without using a metal mask or an FMM is sometimes referred to as a device having an MML (metal maskless) structure.

In this specification and the like, a hole or an electron is sometimes referred to as a “carrier.” Specifically, a hole-injection layer or an electron-injection layer may be referred to as a “carrier-injection layer,” a hole-transport layer or an electron-transport layer may be referred to as a “carrier-transport layer,” and a hole-blocking layer or an electron-blocking layer may be referred to as a “carrier-blocking layer.” Note that the above-described carrier-injection layer, carrier-transport layer, and carrier-blocking layer cannot be distinguished from each other on the basis of the cross-sectional shape, properties, or the like in some cases. Furthermore, one layer may have two or three functions of the carrier-injection layer, the carrier-transport layer, and the carrier-blocking layer in some cases.

In this specification and the like, the light-emitting element includes an EL layer between a pair of electrodes. The EL layer includes at least a light-emitting layer. Examples of a layer included in the EL layer include a light-emitting layer, a carrier-injection layer, a carrier-transport layer, and a carrier-blocking layer.

In this specification and the like, the carrier-injection layer refers to one or both of a hole-injection layer and an electron-injection layer. The carrier-transport layer refers to one or both of a hole-transport layer and an electron-transport layer. The carrier-blocking layer refers to one or both of a hole-blocking layer and an electron-blocking layer.

Note that in this specification and the like, a tapered shape refers to a shape such that at least part of a side surface of a component is inclined with respect to a substrate surface. For example, a tapered shape indicates a shape including a region where the angle formed by the inclined side surface and the substrate surface (such an angle is also referred to as a taper angle) is less than 90°. Note that the side surface of the component and the substrate surface are not necessarily completely flat and may be substantially flat with a slight curvature or substantially flat with slight unevenness.

In this embodiment, a display device of one embodiment of the present invention and a manufacturing method thereof are described.

The display device of one embodiment of the present invention is capable of full-color display. For example, EL layers including at least light-emitting layers are separately formed for the respective colors, whereby the display device capable of full-color display can be manufactured. Alternatively, for example, a coloring layer (also referred to as a color filter) is provided over an EL layer that emits white light, whereby the display device capable of full-color display can be manufactured.

A structure where light-emitting layers in light-emitting elements of different colors (e.g., blue (B), green (G), and red (R)) are separately formed or separately patterned is sometimes referred to as an SBS (Side By Side) structure. A light-emitting element capable of emitting white light may be referred to as a white-light-emitting element.

In the case where a display device including a plurality of light-emitting elements emitting light of different colors, the light-emitting layers emitting light of different colors each need to be formed into an island shape. Also in the case where a display device including a white light-emitting element is manufactured, the light-emitting layer is preferably formed into an island shape so that leakage current that would be generated between adjacent light-emitting elements through the light-emitting layer can be reduced.

Note that in this specification and the like, the term island shape refers to a state where two or more layers formed using the same material in the same step are physically separated from each other. For example, the term island-shaped light-emitting layer refers to a state where the light-emitting layer and its adjacent light-emitting layer are physically separated from each other.

For example, an island-shaped light-emitting layer can be formed by a vacuum evaporation method using a metal mask. However, this method causes a deviation from the designed shape and position of an island-shaped light-emitting layer due to various influences such as a low accuracy of the metal mask, positional deviation between the metal mask and a substrate, a warp of the metal mask, and expansion of the outline of a formed film, for example. Consequently, increasing the definition and aperture ratio of a display device is difficult. In addition, the outline of the layer may blur during vapor deposition, whereby the thickness of an end portion may be reduced. That is, the thickness of the island-shaped light-emitting layer may vary from area to area. In the case of manufacturing a display device with a large size, high definition, or high resolution, the manufacturing yield might be reduced because of low dimensional accuracy of the metal mask and deformation due to heat or the like.

In view of this, in manufacturing the display device of one embodiment of the present invention, patterning of light-emitting layers is performed by a photolithography method without a shadow mask such as a metal mask. Specifically, pixel electrodes are formed for the respective subpixels, and then a light-emitting layer is formed across the pixel electrodes. After that, the light-emitting layer is processed by a photolithography method, for example, so that one island-shaped light-emitting layer is formed per pixel electrode. Thus, the light-emitting layer can be divided into island-shaped light-emitting layers for respective subpixels.

In the case of processing the light-emitting layer into an island shape, a structure is possible where processing is performed by a photolithography method directly on the light-emitting layer. In the structure, damage to the light-emitting layer, e.g., processing damage, might significantly degrade the reliability. In view of the above, in manufacturing the display device of one embodiment of the present invention, as the EL layer, in addition to the light-emitting layer, a mask layer or the like is preferably formed over a functional layer positioned above the light-emitting layer, such as a carrier-blocking layer, a carrier-transport layer, or a carrier-injection layer, or more specifically, a hole-blocking layer, an electron-transport layer, or an electron-injection layer, or the like, followed by the processing of the light-emitting layer and the functional layer into an island shape. Such a method can provide a highly reliable display device. The functional layer between the light-emitting layer and the mask layer can inhibit the light-emitting layer from being exposed on the outermost surface during the manufacturing process of the display device and can reduce damage to the light-emitting layer.

In this specification and the like, a mask film and a mask layer refer to, respectively, a film and a layer that are positioned above at least the light-emitting layer, specifically, a layer processed into an island shape among the layers included in the EL layer, and have a function of protecting the light-emitting layer in the manufacturing process. The mask film can be referred to as a sacrificial film or a protective film, and the mask layer can also be referred to as a sacrificial layer or a protective layer.

The EL layer can include a functional layer below as well as above the light-emitting layer. In the case where the above light-emitting layer is processed into an island shape, a layer positioned below the light-emitting layer (e.g., a carrier-injection layer, a carrier-transport layer, or a carrier-blocking layer, and specifically, a hole-injection layer, a hole-transport layer, or an electron-blocking layer) is preferably processed into an island shape with the same pattern as the light-emitting layer. When the layer positioned below the light-emitting layer is processed into an island shape with the same pattern as the light-emitting layer, a leakage current that would be generated between adjacent subpixels (sometimes referred to as a horizontal-direction leakage current, a horizontal leakage current, or a lateral leakage current) can be reduced. For example, in the case where a hole-injection layer is shared by adjacent subpixels, a horizontal leakage current would be generated because of the hole-injection layer. In the display device of one embodiment of the present invention, the hole-injection layer can be processed into an island shape with the same pattern as the light-emitting layer: hence, a horizontal leakage current between adjacent subpixels is not substantially generated or a horizontal leakage current can be extremely small.

Here, the EL layer is preferably provided to cover an upper surface and a side surface of a pixel electrode. Such a structure can easily increase the aperture ratio compared with the structure in which an end portion of the island-shaped EL layer is positioned on the inner side of an end portion of the pixel electrode.

The pixel electrode preferably has a stacked-layer structure of a plurality of layers containing different materials. For example, in the case where the display device has a top-emission structure and the pixel electrode has a stacked-layer structure of two layers, the first conductive layer and the second conductive layer over the first conductive layer, the first conductive layer can be a layer having higher visible light reflectance than the second conductive layer. In the case where a functional layer positioned below the light-emitting layer includes at least one of a hole-injection layer and a hole-transport layer, for example, and the second conductive layer is in contact with the functional layer, the second conductive layer can be a layer that has a higher work function than the first conductive layer. That is, in the case where the pixel electrode functions as an anode, the second conductive layer can be a layer that has a higher work function than the first conductive layer. Thus, the light-emitting element can have high light extraction efficiency and low driving voltage.

In this specification and the like, visible light refers to light at a wavelength longer than or equal to 400 nm and shorter than 750 nm. The visible light reflectance refers to the reflectance with respect to the light in a predetermined range of wavelengths longer than or equal to 400 nm and shorter than 750 nm. For example, the visible light reflectance may refer to the average or maximum reflectance with respect to the light at all the wavelengths longer than or equal to 400 nm and shorter than 750 nm. The visible light reflectance may refer to the reflectance with respect to light at a specific wavelength that is longer than or equal to 400 nm and shorter than 750 nm.

By contrast, in the case of having a stacked-layer structure of a plurality of layers using different materials, the pixel electrode might change in quality as a result of a reaction occurring between the plurality of layers, for example. In a method of manufacturing the display device of one embodiment of the present invention, for example, in the case where a film formed after formation of the pixel electrode is removed by a wet etching method, a chemical solution sometimes comes into contact with the pixel electrode. The contact of the plurality of layers with the chemical solution might cause galvanic corrosion in the case of the pixel electrode having a stacked-layer structure of the plurality of layers. As a result, at least one layer included in the pixel electrode sometimes changes in quality. This might decrease the yield of the display device and might degrade the reliability of the display device.

In view of the above, in one embodiment of the present invention, the second conductive layer is formed to cover an upper surface and a side surface of the first conductive layer. This can inhibit the chemical solution from coming into contact with the first conductive layer even in the case where a film that is formed after formation of the pixel electrode including the first conductive layer and the second conductive layer is removed by a wet etching method, for example. Accordingly, the occurrence of galvanic corrosion in the pixel electrode can be inhibited, for example. As described above, the display device of one embodiment of the present invention can be manufactured by a high-yield method. In addition, generation of a defect in the display device of one embodiment of the present invention can be inhibited, which makes the display device highly reliable.

Note that it is not necessary to form all layers included in EL layers separately between light-emitting elements that emit light of different colors, and some layers of the EL layers can be formed in the same step. In the method of manufacturing a display device of one embodiment of the present invention, after some layers included in the EL layers are formed into an island shape separately for the respective colors, the mask layer is removed at least partly, and then the other layers (also referred to as a common layer in some cases) included in the EL layers and a common electrode (also referred to as an upper electrode) are formed so as to be shared by the light-emitting elements of different colors, i.e., formed as a single film. For example, a carrier-injection layer and the common electrode can be formed so as to be shared by the light-emitting elements of different colors.

Meanwhile, the carrier-injection layer is often a layer having relatively high conductivity in the EL layer. Accordingly, when the carrier-injection layer is in contact with a side surface of any layer of the EL layers formed into an island shape or a side surface of the pixel electrode, the light-emitting element might be short-circuited. Note that also in the case where the carrier-injection layer is formed into an island shape and the common electrode is formed to be shared by the light-emitting elements of the different colors, the contact between the common electrode and the side surface of the EL layer or the side surface of the pixel electrode might cause the light-emitting element to be short-circuited.

Thus, the display device of one embodiment of the present invention includes an insulating layer covering at least a side surface of the island-shaped light-emitting layer. The insulating layer preferably covers part of an upper surface of the island-shaped light-emitting layer.

Accordingly, the contact of the carrier-injection layer and the common electrode with at least some layer of the island-shaped EL layers and the pixel electrode can be inhibited. Thus, a short circuit in the light-emitting element can be inhibited, leading to an increase in the reliability of the light-emitting element.

In a cross-sectional view; an end portion of the insulating layer preferably has a tapered shape with a taper angle less than 90°. Thus, step disconnection of the common layer and the common electrode provided over the insulating layer can be inhibited. This can inhibit a connection defect due to the step disconnection. In addition, local thinning of the common electrode due to a step can be inhibited from increasing electrical resistance.

In this specification and the like, step disconnection refers to a phenomenon in which a layer, a film, or an electrode is split because of the shape of the formation surface such as a step or a phenomenon in which a locally thinned portion is formed.

As described above, in the method of manufacturing a display device of one embodiment of the present invention, the island-shaped light-emitting layers are formed not by using a fine metal mask but by processing a light-emitting layer formed over the entire surface. Accordingly, a high-resolution display device or a display device with a high aperture ratio, which has been difficult to achieve, can be achieved. Moreover, light-emitting layers can be formed separately for each color, enabling the display device to perform extremely clear display with high contrast and high display quality. In addition, a mask layer provided over a light-emitting layer can reduce damage to the light-emitting layer in the manufacturing process of the display device, increasing the reliability of the light-emitting element.

A formation method using a fine metal mask, for example, does not easily shorten the distance between adjacent light-emitting elements to less than 10 μm: meanwhile, the method employing a photolithography method according to one embodiment of the present invention can shorten the distance between adjacent light-emitting elements, the distance between adjacent EL layers, or the distance between adjacent pixel electrodes to less than 10 μm, 5 μm or less, 3 μm or less, 2 μm or less, 1.5 μm or less, 1 μm or less, or even 0.5 μm or less in a process over a glass substrate. Using a light exposure apparatus for LSI can further shorten the distance between adjacent light-emitting elements, the distance between adjacent EL layers, or the distance between adjacent pixel electrodes to 500 nm or less, 200 nm or less, 100 nm or less, or even 50 nm or less, for example, in a process over a silicon wafer. Accordingly, the area of a non-light-emitting region that may exist between two light-emitting elements can be significantly reduced, and the aperture ratio can be close to 100%. For example, the display device of one embodiment of the present invention can achieve an aperture ratio higher than or equal to 40%, higher than or equal to 50%, higher than or equal to 60%, higher than or equal to 70%, higher than or equal to 80%, or higher than or equal to 90% and lower than 100%.

Increasing the aperture ratio of the display device can improve the reliability of the display device. Specifically, with reference to the lifetime of a display device including an organic EL element and having an aperture ratio of 10%, a display device having an aperture ratio of 20% (i.e., having an aperture ratio two times the reference) has a lifetime approximately 3.25 times the reference, and a display device having an aperture ratio of 40% (i.e., having an aperture ratio four times the reference) has a lifetime approximately 10.6 times the reference. Thus, the density of current flowing to the organic EL element can be reduced with the increasing aperture ratio, and accordingly the lifetime of the display device can be increased. The display device of one embodiment of the present invention can have a higher aperture ratio and thus can have higher display quality. Furthermore, the display device has excellent effect that the reliability (especially the lifetime) can be significantly improved with increasing aperture ratio.

In addition, a pattern of the light-emitting layer itself can be made much smaller than that in the case of using a fine metal mask. For example, in the case of using a metal mask for forming light-emitting layers separately, the thickness varies between the center and the edge of the pattern, which causes a reduction in an effective area that can be used for a light-emitting region with respect to the entire pattern area. By contrast, according to the above manufacturing method, a film formed to a uniform thickness is processed and accordingly island-shaped light-emitting layers can be formed to a uniform thickness: thus, even with a fine pattern, almost the entire area can be used as a light-emitting region. Consequently, a display device having both a high resolution and a high aperture ratio can be manufactured. Furthermore, the display device can be reduced in size and weight.

Specifically, for example, the display device of one embodiment of the present invention can have a definition higher than or equal to 2000 ppi, preferably higher than or equal to 3000 ppi, further preferably higher than or equal to 5000 ppi, still further preferably higher than or equal to 6000 ppi, and lower than or equal to 20000 ppi or lower than or equal to 30000 ppi.

Structure Example 1

FIG.1is a plan view illustrating a structure example of a display device100. The display device100includes a pixel portion107in which a plurality of pixels108are arranged in a matrix. The pixel108includes a subpixel110R, a subpixel110G, and a subpixel110B.FIG.1illustrates subpixels110arranged in two rows and six columns, which form pixels108in two rows and two columns.

In this specification and the like, for example, matters common to the subpixel110R, the subpixel110G, and the subpixel110B are sometimes described using the collective term “subpixel110.” In the same manner, in the description common to other components that are distinguished by alphabets, reference numerals without alphabets are sometimes used.

The subpixel110R emits red light, the subpixel110G emits green light, and the subpixel110B emits blue light. Accordingly, an image can be displayed on the pixel portion107. Thus, the pixel portion107can be referred to as a display portion. Note that in this embodiment, subpixels of three colors of red (R), green (G), and blue (B) are given as examples: however, subpixels of three colors of yellow (Y), cyan (C), and magenta (M) may be used, for example. The number of kinds of subpixels is not limited to three, and four or more kinds of subpixels may be used. The four subpixels can be of four colors of R, G, B, and white (W), of four colors of R, G, B, and Y, or of four colors of R, G, B, and infrared light (IR), for example.

It also can be said that stripe arrangement is employed for the pixels108illustrated inFIG.1. Note that the arrangement method that can be employed for the pixels108is not limited thereto: another arrangement method such as stripe arrangement, S stripe arrangement, delta arrangement, Bayer arrangement, or zigzag arrangement may be used, or PenTile arrangement, diamond arrangement, or the like can be used.

In this specification and the like, the row direction is referred to as X direction and the column direction is referred to as Y direction in some cases. The X direction and the Y direction intersect with each other and are perpendicular to each other, for example.

FIG.1illustrates an example where subpixels of different colors are arranged in the X direction and subpixels of the same color are arranged in the Y direction. Note that subpixels of different colors may be arranged in the Y direction, and subpixels of the same color may be arranged in the X direction.

A region141and a connection portion140are provided outside the pixel portion107, and the region141is positioned between the pixel portion107and the connection portion140. An EL layer113is provided in the region141. A conductive layer111C is provided in the connection portion140.

AlthoughFIG.1illustrates an example where the region141and the connection portion140are positioned on the right side of the pixel portion107in the plan view, the position of the region141and the connection portion140is not particularly limited. The region141and the connection portion140are provided on at least one of the upper side, the right side, the left side, and the lower side of the pixel portion107in the plan view, and may be provided to surround the four sides of the pixel portion107. The top surface shapes of the region141and the connection portion140can be a belt-like shape, an L shape, a U shape, a frame-like shape, or the like. In addition, the numbers of the regions141and the connection portions140can be one or more.

FIG.2Ais a cross-sectional view along the dashed-dotted line A1-A2 inFIG.1and illustrates a structure example of the pixel108provided in the pixel portion107. As illustrated inFIG.2A, the display device100includes an insulating layer101, a conductive layer102over the insulating layer101, an insulating layer103over the insulating layer101and over the conductive layer102, an insulating layer104over the insulating layer103, and an insulating layer105over the insulating layer104. The insulating layer101is provided over a substrate (not illustrated). An opening reaching the conductive layer102is provided in the insulating layer105, the insulating layer104, and the insulating layer103, and a plug106is provided so as to fill the opening.

In the pixel portion107, a light-emitting element130is provided over the insulating layer105and over the plug106. A protective layer131is provided to cover the light-emitting element130. The substrate120is bonded to the protective layer131with the resin layer122. In a region between adjacent light-emitting elements130, an insulating layer125and an insulating layer127over the insulating layer125are provided.

AlthoughFIG.2Aillustrates a plurality of cross sections of the insulating layer125and the insulating layer127, the insulating layer125and the insulating layer127are each a continuous layer in the plan view of the display device100. In other words, the display device100can have a structure including one insulating layer125and one insulating layer127, for example. Note that the display device100may include a plurality of insulating layers125which are separated from each other and a plurality of insulating layers127which are separated from each other.

InFIG.2A, a light-emitting element130R, a light-emitting element130G, and a light-emitting element130B are shown as the light-emitting element130. The light-emitting element130R, the light-emitting element130G, and the light-emitting element130B emit light of different colors. For example, the light-emitting element130R can emit red light, the light-emitting element130G can emit green light, and the light-emitting element130B can emit blue light. The light-emitting element130R, the light-emitting element130G, or the light-emitting element130B may emit light of cyan, magenta, yellow, or white or light such as infrared light.

The display device of one embodiment of the present invention is a top-emission display device where light is emitted in the direction opposite to a substrate over which the light-emitting elements are formed.

As the light-emitting element130, an OLED (Organic Light Emitting Diode) or a QLED (Quantum-dot Light Emitting Diode) is preferably used, for example. Examples of a light-emitting substance contained in the light-emitting element130include a substance exhibiting fluorescence (a fluorescent material), a substance exhibiting phosphorescence (a phosphorescent material), an inorganic compound (e.g., a quantum dot material), and a substance exhibiting thermally activated delayed fluorescence (a TADF material). An LED such as a micro-LED (Light Emitting Diode) can be used as the light-emitting element130.

The light-emitting element130R includes a conductive layer111R over the plug106and the insulating layer105, a conductive layer112R covering the upper surface and the side surface of the conductive layer111R, an EL layer113R covering the upper surface and the side surface of the conductive layer112R, a common layer114over the EL layer113R, and a common electrode115over the common layer114. Here, the conductive layer111R and the conductive layer112R form a pixel electrode of the light-emitting element130R. Note that in the light-emitting element130R, the EL layer113R and the common layer114can be collectively referred to as an EL layer.

The light-emitting element130G includes a conductive layer111G over the plug106and the insulating layer105, a conductive layer112G covering the upper surface and the side surface of the conductive layer111G, an EL layer113G covering the upper surface and the side surface of the conductive layer112G, the common layer114over the EL layer113G, and the common electrode115over the common layer114. Here, the conductive layer111G and the conductive layer112G form a pixel electrode of the light-emitting element130G. Note that in the light-emitting element130G, the EL layer113G and the common layer114can be collectively referred to as an EL layer.

The light-emitting element130B includes a conductive layer111B over the plug106and the insulating layer105, a conductive layer112B covering the upper surface and the side surface of the conductive layer111B, an EL layer113B covering the upper surface and the side surface of the conductive layer112B, the common layer114over the EL layer113B, and the common electrode115over the common layer114. Here, the conductive layer111B and the conductive layer112B form a pixel electrode of the light-emitting element130B. Note that in the light-emitting element130B, the EL layer113B and the common layer114can be collectively referred to as an EL layer.

One of the pixel electrode and the common electrode of the light-emitting element functions as an anode, and the other thereof functions as a cathode. Hereinafter, the pixel electrode may function as the anode and the common electrode may function as the cathode unless otherwise specified.

Each of the EL layer113R, the EL layer113G, and the EL layer113B includes at least a light-emitting layer. For example, the EL layer113R, the EL layer113G, and the EL layer113B can respectively include a light-emitting layer that emits red light, a light-emitting layer that emits green light, and a light-emitting layer that emits blue light. The EL layer113R, the EL layer113G, or the EL layer113B may emit cyan light, magenta light, yellow light, white light, infrared light, or the like.

The EL layer113R, the EL layer113G, and the EL layer113B are separated from each other. Providing the island-shaped EL layer113in each of the light-emitting elements130can inhibit a leakage current between the adjacent light-emitting elements130. This can inhibit crosstalk due to unintended light emission, so that the display device can achieve extremely high contrast. The display device can achieve high current efficiency at low luminance, in particular.

The island-shaped EL layer113can be formed by forming an EL film and processing the EL film by a photolithography method, for example. For example, the EL layer113R can be formed by forming and processing an EL film to be the EL layer113R, the EL layer113G can be formed by forming and processing an EL film to be the EL layer113G, and the EL layer113B can be formed by forming and processing an EL film to be the EL layer113B.

The EL layer113is provided to cover an upper surface and a side surface of the pixel electrode of the light-emitting element130. In this structure, the aperture ratio of the display device100can be easily increased as compared to the structure where an end portion of the EL layer113is positioned more inside than the end portion of the pixel electrode. Covering the side surface of the pixel electrode of the light-emitting element130with the EL layer113inhibits contact between the pixel electrode and the common electrode115, thereby inhibiting a short circuit in the light-emitting element130. Furthermore, the distance between the end portion of the EL layer113and the light-emitting region in the EL layer113, i.e., the region overlapping with the pixel electrode, the EL layer113, and the common electrode115, can be increased. Since the end portion of the EL layer113might be damaged by processing, the use of a region away from the end portion of the EL layer113as the light-emitting region can improve the reliability of the light-emitting element130in some cases.

In the display device of one embodiment of the present invention, the pixel electrode of the light-emitting element has a stacked-layer structure of a plurality of layers. For example, in the example illustrated inFIG.2A, the pixel electrode of the light-emitting element130is a stack of the conductive layer111and the conductive layer112. In the case where the display device100has a top-emission structure and the pixel electrode of the light-emitting element130functions as an anode, for example, the conductive layer111can have higher visible light reflectance than the conductive layer112, and the conductive layer112can have a higher work function than the conductive layer111. As the pixel electrode has higher visible light reflectance, for example, transmission of light emitted from the EL layer113through the pixel electrode can be more inhibited, which leads to the increased efficiency of extraction of the light emitted from the EL layer113in the case of the display device100having a top-emission structure. Moreover, as the pixel electrode has a higher work function, hole injection into the EL layer113is easier and accordingly the driving voltage of the light-emitting element can be lower in the case where the pixel electrode functions as an anode. Thus, when the pixel electrode of the light-emitting element130has a stacked-layer structure of the conductive layer111with high visible light reflectance and the conductive layer112with a high work function, the light-emitting element130can have high light extraction efficiency and a low driving voltage.

In the case where the conductive layer111has higher visible light reflectance than the conductive layer112, the visible light reflectance of the conductive layer111is preferably higher than or equal to 40% and lower than or equal to 100%, further preferably higher than or equal to 70% and lower than or equal to 100%, for example. The conductive layer112can be an electrode having a property of transmitting visible light (also referred to as a transparent electrode).

In this specification and the like, a transparent electrode refers to an electrode whose transmittance to visible light is higher than or equal to 40%.

The conductive layer111of the light-emitting element130has high reflectance with respect to the light emitted from the EL layer113. For example, in the case where the EL layer113emits infrared light, the conductive layer111can have high reflectance with respect to infrared light. In the case where the pixel electrode of the light-emitting element130functions as a cathode, the conductive layer112preferably has a lower work function than the conductive layer111, for example.

By contrast, in the case of having a stacked-layer structure of a plurality of layers, the pixel electrode might change in quality as a result of a reaction occurring between the plurality of layers, for example. In the manufacture of the display device100, for example, in the case where a film formed after formation of the pixel electrode is removed by a wet etching method, a chemical solution sometimes comes into contact with the pixel electrode, although the details are described later. The contact of the plurality of layers with the chemical solution might cause galvanic corrosion in the case of the pixel electrode having a stacked-layer structure of the plurality of layers. As a result, at least one layer included in the pixel electrode sometimes changes in quality. This might decrease the yield of the display device and might degrade the reliability of the display device.

In view of the above, the conductive layer112is formed to cover the upper surface and the side surface of the conductive layer111in the display device100. This can inhibit the chemical solution from coming into contact with the conductive layer111even in the case where a film that is formed after formation of the pixel electrode including the conductive layer111and the conductive layer112is removed by a wet etching method, for example. Accordingly, the occurrence of galvanic corrosion in the pixel electrode can be inhibited, for example. As described above, the display device100can be manufactured by a high-yield method. In addition, generation of a defect in the display device100can be inhibited, which makes the display device100highly reliable.

A metal material can be used for the conductive layer111, for example. For example, a metal such as aluminum (Al), magnesium (Mg), titanium (Ti), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), gallium (Ga), zinc (Zn), indium (In), tin (Sn), molybdenum (Mo), tantalum (Ta), tungsten (W), palladium (Pd), gold (Au), platinum (Pt), silver (Ag), yttrium (Y), or neodymium (Nd) or an alloy containing an appropriate combination of any of these metals can be used. As an alloy material, for example, an alloy containing aluminum (an aluminum alloy), such as an alloy of aluminum, nickel, and lanthanum (Al—Ni—La) or an alloy containing silver, such as an alloy of silver and magnesium and an alloy of silver, palladium, and copper (also referred to as Ag—Pd—Cu or APC) can be used.

For the conductive layer112, an oxide containing one or more selected from indium, tin, zinc, gallium, titanium, aluminum, and silicon can be used. For example, it is preferable to use a conductive oxide containing one or more of indium oxide, indium tin oxide, indium zinc oxide, zinc oxide, zinc oxide containing gallium, titanium oxide, indium titanium oxide, zinc titanate, aluminum zinc oxide, indium zinc oxide containing gallium, indium zinc oxide containing aluminum, indium tin oxide containing silicon, indium zinc oxide containing silicon, and the like. In particular, in the case where the pixel electrode functions as an anode, indium tin oxide containing silicon can be suitably used for the conductive layer112because of having a high work function, for example, a work function higher than or equal to 4.0 eV.

The conductive layer111may have a stacked-layer structure of a plurality of layers containing different materials and the conductive layer112may have a stacked-layer structure of a plurality of layers containing different materials, though the details are described later. In that case, the conductive layer111may include a layer formed using a material that can be used for the conductive layer112, such as a conductive oxide. The conductive layer112may include a layer formed using a material that can be used for the conductive layer111, such as a metal material. In the case where the conductive layer112has a stacked-layer structure of two or more layers, for example, a layer in contact with the conductive layer111can be formed using a material that can be used for the conductive layer111, such as a metal material.

An end portion of the conductive layer111preferably has a tapered shape. Specifically, the end portion of the conductive layer111preferably has a tapered shape with a taper angle less than 90°. In that case, the conductive layer112provided along the side surface of the conductive layer111also has a tapered shape. Accordingly, the EL layer113provided along the side surface of the conductive layer112also has a tapered shape. When the side surface of the conductive layer112has a tapered shape, coverage with the EL layer113provided along the side surface of the conductive layer112can be improved.

InFIG.2A, an insulating layer (also referred to as a bank or a structure body) that covers an upper end portion of the conductive layer112R is not provided between the conductive layer112R and the EL layer113R. An insulating layer that covers an upper end portion of the conductive layer112G is not provided between the conductive layer112G and the EL layer113G. An insulating layer that covers an upper end portion of the conductive layer112B is not provided between the conductive layer112B and the EL layer113B. Thus, the distance between adjacent light-emitting elements130can be extremely small. Accordingly, the display device can have high resolution or high definition. In addition, a mask for forming the insulating layer is not needed, which leads to a reduction in manufacturing cost of the display device.

Furthermore, light emitted from the EL layer113can be extracted efficiently with the structure where an insulating layer covering the end portion of the conductive layer112is not provided between the conductive layer112and the EL layer113. Therefore, the display device100can significantly reduce the viewing angle dependence. A reduction in the viewing angle dependence leads to an increase in visibility of an image on the display device100. For example, in the display device100, the viewing angle (the maximum angle with a certain contrast ratio maintained when the screen is seen from an oblique direction) can be greater than or equal to 100° and less than 180°, preferably greater than or equal to 150° and less than or equal to 170°. Note that the above viewing angle refers to that in both the vertical direction and the horizontal direction.

The insulating layer101, the insulating layer103, and the insulating layer105function as interlayer insulating layers. As the insulating layer101, the insulating layer103, and the insulating layer105, a variety of inorganic insulating films such as an oxide insulating film, a nitride insulating film, an oxynitride insulating film, and a nitride oxide insulating film can be suitably used: specifically, a silicon oxide film, a silicon oxynitride film, an aluminum oxide film, a silicon nitride film, or a silicon nitride oxide film can be used, for example.

Note that in this specification and the like, oxynitride refers to a material that contains more oxygen than nitrogen, and nitride oxide refers to a material that contains more nitrogen than oxygen. For example, in the case where silicon oxynitride is described, it refers to a material that contains more oxygen than nitrogen in its composition. In the case where silicon nitride oxide is described, it refers to a material that contains more nitrogen than oxygen in its composition.

The insulating layer104functions as a barrier layer that inhibits entry of impurities such as water into, for example, the light-emitting element130. As the insulating layer104, it is possible to use, for example, a film in which hydrogen or oxygen is less likely to be diffused than in a silicon oxide film, such as a silicon nitride film, an aluminum oxide film, or a hafnium oxide film.

Specifically, the thickness of the insulating layer105in a region not overlapping with the conductive layer111is sometimes smaller than that of the insulating layer105in a region overlapping with the conductive layer111. That is, the insulating layer105may have a depressed portion in the region that does not overlap with the conductive layer111. The depressed portion is formed because of the step of forming the conductive layer111, for example.

The conductive layer102functions as a wiring. The conductive layer102is electrically connected to the light-emitting element130through the plug106.

For the conductive layer102and the plug106, it is possible to use a variety of conductive materials, for example, a metal such as aluminum (Al), magnesium (Mg), titanium (Ti), chromium (Cr), nickel (Ni), copper (Cu), yttrium (Y), zirconium (Zr), tin (Sn), zinc (Zn), silver (Ag), platinum (Pt), gold (Au), molybdenum (Mo), tantalum (Ta), or tungsten (W) or an alloy containing the metal as its main component (e.g., APC). For the conductive layer102and the plug106, an oxide such as tin oxide or zinc oxide may be used.

For the light-emitting element130, a single structure (a structure including only one light-emitting unit) can be employed.

As described above, each of the EL layer113R, the EL layer113G, and the EL layer113B includes at least a light-emitting layer. For example, the EL layer113R, the EL layer113G, and the EL layer113B can respectively include a light-emitting layer that emits red light, a light-emitting layer that emits green light, and a light-emitting layer that emits blue light.

The EL layer113R, the EL layer113G, and the EL layer113B may each include one or more of a hole-injection layer, a hole-transport layer, a hole-blocking layer, a charge-generation layer (also referred to as an intermediate layer), an electron-blocking layer, an electron-transport layer, and an electron-injection layer.

In this specification and the like, a functional layer refers to a layer that is included in the EL layer and is other than the light-emitting layer.

In the case where the pixel electrode of the light-emitting element130functions as an anode and the common electrode115functions as a cathode, for example, the EL layer113R, the EL layer113G, and the EL layer113B may each include a hole-injection layer, a hole-transport layer, a light-emitting layer, and an electron-transport layer in this order. In other words, the EL layer113can have a structure in which, for example, a first functional layer including a hole-injection layer and a hole-transport layer, a light-emitting layer, and a second functional layer including an electron-transport layer are stacked in order from the bottom. The EL layer113may include an electron-blocking layer between the hole-transport layer and the light-emitting layer. The EL layer113may include a hole-blocking layer between the electron-transport layer and the light-emitting layer. The EL layer113may include an electron-injection layer over the electron-transport layer. Note that the first functional layer may be configured to include one of the hole-injection layer and the hole-transport layer and not to include the other. The second functional layer may include the electron-injection layer and does not necessarily include the electron-transport layer.

In the case where the pixel electrode of the light-emitting element130functions as a cathode and the common electrode115functions as an anode, for example, the EL layer113R, the EL layer113G, and the EL layer113B may each include an electron-injection layer, an electron-transport layer, a light-emitting layer, and a hole-transport layer in this order. In other words, the EL layer113can have a structure in which, for example, a first functional layer including an electron-injection layer and an electron-transport layer, a light-emitting layer, and a second functional layer including a hole-transport layer are stacked in order from the bottom. The EL layer113may include a hole-blocking layer between the electron-transport layer and the light-emitting layer. The EL layer113may include an electron-blocking layer between the hole-transport layer and the light-emitting layer. The EL layer113may include a hole-injection layer over the hole-transport layer. Note that the first functional layer may be configured to include one of the electron-injection layer and the electron-transport layer and not to include the other. The second functional layer may include the hole-injection layer and does not necessarily include the hole-transport layer.

As described above, the EL layer113R, the EL layer113G, and the EL layer113B each preferably include a light-emitting layer and a carrier-transport layer over the light-emitting layer. The EL layer113R, the EL layer113G, and the EL layer113B each preferably include a light-emitting layer and a carrier-blocking layer over the light-emitting layer. Alternatively, the EL layer113R, the EL layer113G, and the EL layer113B each preferably include a light-emitting layer, a carrier-blocking layer over the light-emitting layer, and a carrier-transport layer over the carrier-blocking layer. Since the surfaces of the EL layer113R, the EL layer113G, and the EL layer113B are exposed in the manufacturing process of the display device, providing one or both of the carrier-transport layer and the carrier-blocking layer over the light-emitting layer inhibits the light-emitting layer from being exposed on the outermost surface, so that damage to the light-emitting layer can be reduced. As a result, the reliability of the light-emitting element can be increased.

The upper temperature limit of the compounds included in the EL layer113R, the EL layer113G, and the EL layer113B is preferably higher than or equal to 100° C., and lower than or equal to 180° C., further preferably higher than or equal to 120° C., and lower than or equal to 180° C., still further preferably higher than or equal to 140° C., and lower than or equal to 180° C. For example, the glass transition temperature (Tg) of these compounds is preferably higher than or equal to 100° C., and lower than or equal to 180° C., further preferably higher than or equal to 120° C., and lower than or equal to 180° C., still further preferably higher than or equal to 140° C., and lower than or equal to 180° C.

In particular, the upper temperature limit of the functional layer provided over the light-emitting layer is preferably high. It is further preferable that the upper temperature limit of the functional layer provided on and in contact with the light-emitting layer be high. When such a functional layer has high heat resistance, the light-emitting layer can be effectively protected, resulting in less damage to the light-emitting layer.

The functional layer provided over the light-emitting layer preferably contains an organic compound that includes a heteroaromatic ring skeleton including one selected from a pyridine ring, a diazine ring, and a triazine ring and a bicarbazole skeleton or an organic compound that includes a fused heteroaromatic ring skeleton including a pyridine ring or a diazine ring and a bicarbazole skeleton, and the organic compound preferably has Tg higher than or equal to 100° C., and lower than or equal to 180° C., preferably higher than or equal to 120° C., and lower than or equal to 180° C., further preferably higher than or equal to 140° C., and lower than or equal to 180° C. The functional layer using such an organic compound can have one or both of a function of a hole-blocking layer and a function of an electron-transport layer. Note that the functional layer using such an organic compound is not necessarily positioned above (on the upper electrode side) of the light-emitting layer and may be provided below the light-emitting layer (on the lower electrode side).

The upper temperature limit of the light-emitting layer is preferably high. In this case, the light-emitting layer can be inhibited from being damaged by heating and being decreased in emission efficiency and lifetime.

The EL layer113R, the EL layer113G, and the EL layer113B can each include a first light-emitting unit, a charge-generation layer, and a second light-emitting unit, for example.

The second light-emitting unit preferably includes a light-emitting layer and a carrier-transport layer over the light-emitting layer. Alternatively, the second light-emitting unit preferably includes a light-emitting layer and a carrier-blocking layer over the light-emitting layer. Alternatively, the second light-emitting unit preferably includes a light-emitting layer, a carrier-blocking layer over the light-emitting layer, and a carrier-transport layer over the carrier-blocking layer. Since the surface of the second light-emitting unit is exposed in the manufacturing process of the display device, providing one or both of the carrier-transport layer and the carrier-blocking layer over the light-emitting layer inhibits the light-emitting layer from being exposed on the outermost surface, so that damage to the light-emitting layer can be reduced. Accordingly, the reliability of the light-emitting element can be improved. Note that in the case where three or more light-emitting units are provided, the uppermost light-emitting unit preferably includes a light-emitting layer and one or both of a carrier-transport layer and a carrier-blocking layer over the light-emitting layer.

In the case where the pixel electrode of the light-emitting element130functions as the anode and the common electrode115functions as the cathode, the common layer114includes at least one of an electron-injection layer and an electron-transport layer and, for example, includes an electron-injection layer. Alternatively, the common layer114may include a stack of an electron-transport layer and an electron-injection layer. Meanwhile, in the case where the pixel electrode of the light-emitting element130functions as the cathode and the common electrode115functions as the anode, the common layer114includes at least one of a hole-injection layer and a hole-transport layer and, for example, includes a hole-injection layer. Alternatively, the common layer114may include a stack of a hole-transport layer and a hole-injection layer. The common layer114is shared by the light-emitting element130R, the light-emitting element130G, and the light-emitting element130B.

Like the common layer114, the common electrode115is shared by the light-emitting element130R, the light-emitting element130G, and the light-emitting element130B.

The common electrode115can be formed successively without a process such as etching between formations of the common layer114and the common electrode115. For example, after the common layer114is formed in a vacuum, the common electrode115can be formed in a vacuum without exposing the substrate to the air. In other words, the common layer114and the common electrode115can be successively formed in a vacuum. Accordingly, the lower surface of the common electrode115can be a clean surface, as compared to the case where the common layer114is not provided in the display device100. Thus, the light-emitting element130can have high reliability and favorable characteristics.

In the example illustrated inFIG.2A, a mask layer118R is provided over the EL layer113R included in the light-emitting element130R, a mask layer118G is provided over the EL layer113G included in the light-emitting element130G, and a mask layer118B is provided over the EL layer113B included in the light-emitting element130B. The mask layer118R is a remaining portion of the mask layer provided over the EL layer113R when the EL layer113R is processed. Similarly, the mask layer118G is a remaining portion of the mask layer provided at the time of forming the EL layer113G, and the mask layer118B is a remaining portion of the mask layer provided at the time of forming the EL layer113B. In the display device100, the mask layer used to protect the EL layer at the time of forming the display device100may partly remain in this manner. Two or all of the mask layer118R, the mask layer118G, and the mask layer118B may be formed using the same material, or they may be formed using different materials. Note that hereinafter the mask layer118R, the mask layer118G, and the mask layer118B may be collectively referred to as the mask layer118.

InFIG.2A, one end portion of the mask layer118R is aligned or substantially aligned with the end portion of the EL layer113R, and the other end portion of the mask layer118R is positioned over the EL layer113R. Here, the other end portion of the mask layer118R preferably overlaps with the conductive layer111R. In that case, the other end portion of the mask layer118R is likely to be formed on a substantially flat surface of the EL layer113R. The same applies to the mask layer118G and the mask layer118B. The mask layer118remains between the upper surface of the EL layer113processed into an island shape and the insulating layer125, for example.

In the case where end portions are aligned or substantially aligned with each other and the case where top surface shapes are the same or substantially the same, it can be said that at least part of outlines of stacked layers overlap with each other in a plan view. The case where at least part of outlines of the upper layer and the lower layer overlap with each other includes the case where the layers are processed with the use of the same mask pattern or mask patterns that are partly the same, for example. However, in some cases, the outlines do not completely overlap with each other and the upper layer is positioned on the inner side of the lower layer or the upper layer is positioned on the outer side of the lower layer: such a case is also represented as “end portions are substantially aligned with each other” or “top surface shapes are substantially the same.”

The side surfaces of the EL layer113R, the EL layer113G, and the EL layer113B are covered with the insulating layer125. The insulating layer127overlaps with the side surfaces of the EL layer113R, the EL layer113G, and the EL layer113B with the insulating layer125therebetween.

The upper surfaces of the EL layer113R, the EL layer113G, and the EL layer113B are partly covered with the mask layer118. The insulating layer125and the insulating layer127overlap with part of the upper surfaces of the EL layer113R, the EL layer113G, and the EL layer113B with the mask layer118therebetween.

Covering the side surfaces and part of the upper surfaces of the EL layer113R, the EL layer113G, and the EL layer113B with at least one of the insulating layer125, the insulating layer127, and the mask layer118can inhibit the common layer114and the common electrode115from being in contact with the side surfaces of the EL layer113R, the EL layer113G, and the EL layer113B and thus inhibit a short circuit of the light-emitting element130. Thus, the reliability of the light-emitting element130can be increased.

The thicknesses of the EL layer113R, the EL layer113G, and the EL layer113B can be different from each other. For example, the thicknesses of the EL layer113R, the EL layer113G, and the EL layer113B are preferably set to match an optical path length that intensifies light emitted from each EL layer. Thus, a microcavity structure is achieved, and the color purity of light emitted from the subpixels110can be improved.

The insulating layer125is preferably in contact with the side surfaces of the EL layer113R, the EL layer113G, and the EL layer113B. In that case, peeling of the EL layer113R, the EL layer113G, and the EL layer113B can be inhibited. When the insulating layer125is closely attached to the EL layer113R, the EL layer113G, or the EL layer113B, the effect of fixing or bonding the adjacent EL layers113by the insulating layer125is obtained. Thus, the reliability of the light-emitting element130can be increased. In addition, the yield of the light-emitting element can be increased.

The insulating layer125and the insulating layer127cover both the side surfaces and part of the upper surfaces of the EL layer113R, the EL layer113G, and the EL layer113B, as illustrated inFIG.2A, whereby peeling of the EL layers113can be more favorably inhibited and the reliability of the light-emitting element130can be more favorably increased. In addition, the yield of the light-emitting element130can be more favorably increased.

In the example inFIG.2A, the EL layer113R, the mask layer118R, the insulating layer125, and the insulating layer127are stacked in the position over the end portion of the conductive layer112R. Similarly, the EL layer113G, the mask layer118G, the insulating layer125, and the insulating layer127are stacked over the end portion of the conductive layer112G; and the EL layer113B, the mask layer118B, the insulating layer125, and the insulating layer127are stacked over the end portion of the conductive layer112B.

InFIG.2A, the end portion of the conductive layer112R is covered with the EL layer113R, and the insulating layer125includes a region in contact with the side surface of the EL layer113R. Similarly, the end portion of the conductive layer112G is covered with the EL layer113G, the end portion of the conductive layer112B is covered with the EL layer113B, and the insulating layer125includes regions in contact with the side surface of the EL layer113G and the side surface of the EL layer113B.

The insulating layer127is provided over the insulating layer125to fill a depressed portion formed in the insulating layer125. The insulating layer127can overlap with the side surfaces and part of the upper surfaces of the EL layer113R, the EL layer113G, and the EL layer113B, with the insulating layer125therebetween. The insulating layer127preferably covers at least part of the side surface of the insulating layer125.

The insulating layer125and the insulating layer127can fill a gap between adjacent island-shaped layers. Accordingly, extreme unevenness of the formation surface of the layers, or more specifically, the common layer114, the common electrode115, and the like provided over the island-shaped layers can be reduced, and the formation surface can be made flatter. This can further improve the coverage with the common layer114, the common electrode115, and the like can be improved.

The common layer114and the common electrode115are provided over the EL layer113R, the EL layer113G, the EL layer113B, the mask layer118, the insulating layer125, and the insulating layer127. Before the insulating layer125and the insulating layer127are provided, there is a step due to a region where the pixel electrode and the island-shaped EL layer113are provided and a region where neither the pixel electrode nor the island-shaped EL layer113is provided (a region between the light-emitting elements130). In the display device100, the step can be eliminated with the insulating layer125and the insulating layer127, and the coverage with the common layer114and the common electrode115can be improved. This can inhibit a connection defect due to the step disconnection. In addition, local thinning of the common electrode115due to a step can be inhibited from increasing electrical resistance.

The upper surface of the insulating layer127preferably has a shape with higher flatness and may have a protruding portion, a convex surface, a concave surface, or a depressed portion. For example, the upper surface of the insulating layer127preferably has a smooth convex shape with high planarity.

Note that in the display device100, the insulating layer127is provided over the insulating layer125to fill the depressed portion formed in the insulating layer125. Moreover, the insulating layer127is provided between the island-shaped EL layers113. In other words, the display device100employs a process in which an island-shaped EL layer113is formed and then the insulating layer127is provided to overlap with an end portion of the island-shaped EL layer113(hereinafter referred to as a process1). As a process different from the process1, there is a process in which a pixel electrode is formed to have an island shape, an insulating layer that covers an end portion of the pixel electrode is formed, and then an island-shaped EL layer113is formed over the pixel electrode and the insulating layer (hereinafter referred to as a process2).

The above process1is preferable to the above process2because of having a wider margin. Specifically, the above process1has a wider margin with respect to alignment accuracy between different patterning steps than the above process2and can provide display devices with few characteristics variations. The method of manufacturing the display device100is based on the above process1and thus, display devices with few variations and high display quality can be provided.

Next, examples of materials of the insulating layer125and the insulating layer127are described.

The insulating layer125can be formed using an inorganic material. As the insulating layer125, an inorganic insulating film such as an oxide insulating film, a nitride insulating film, an oxynitride insulating film, or a nitride oxide insulating film can be used, for example. The insulating layer125may have a single-layer structure or a stacked-layer structure. Examples of the oxide insulating film include a silicon oxide film, an aluminum oxide film, a magnesium oxide film, an indium-gallium-zinc oxide film, a gallium oxide film, a germanium oxide film, an yttrium oxide film, a zirconium oxide film, a lanthanum oxide film, a neodymium oxide film, a hafnium oxide film, and a tantalum oxide film. Examples of the nitride insulating film include a silicon nitride film and an aluminum nitride film. Examples of the oxynitride insulating film include a silicon oxynitride film and an aluminum oxynitride film. Examples of the nitride oxide insulating film include a silicon nitride oxide film and an aluminum nitride oxide film. In particular, aluminum oxide is preferably used because it has high selectivity with respect to the EL layer113in etching and has a function of protecting the EL layer113when the insulating layer127to be described later is formed. In particular, when an inorganic insulating film such as an aluminum oxide film, a hafnium oxide film, or a silicon oxide film that is formed by an atomic layer deposition (ALD) method is used for the insulating layer125, it is possible to form the insulating layer125that has few pinholes and an excellent function of protecting the EL layer113. The insulating layer125may have a stacked-layer structure of a film formed by an ALD method and a film formed by a sputtering method. The insulating layer125may have a stacked-layer structure of an aluminum oxide film formed by an ALD method and a silicon nitride film formed by a sputtering method, for example.

The insulating layer125preferably has a function of a barrier insulating layer against at least one of water and oxygen. Alternatively, the insulating layer125preferably has a function of inhibiting diffusion of at least one of water and oxygen. Alternatively, the insulating layer125preferably has a function of capturing or fixing (also referred to as gettering) at least one of water and oxygen.

Note that in this specification and the like, a barrier insulating layer refers to an insulating layer having a barrier property. A barrier property in this specification and the like refers to a function of inhibiting diffusion of a particular substance (also referred to as having low permeability). Alternatively, a barrier property refers to a function of capturing or fixing a particular substance.

When the insulating layer125has a function of a barrier insulating layer or a gettering function, entry of impurities, typically, at least one of water and oxygen, which might diffuse into the light-emitting elements130from the outside can be inhibited. With this structure, a highly reliable light-emitting element and a highly reliable display device can be provided.

The insulating layer125preferably has a low impurity concentration. In this case, deterioration of the EL layer113due to entry of impurities from the insulating layer125into the EL layer113can be inhibited. In addition, when the impurity concentration is reduced in the insulating layer125, a barrier property against at least one of water and oxygen can be increased. For example, the insulating layer125preferably has one of a sufficiently low hydrogen concentration and a sufficiently low carbon concentration, desirably has both of them.

Note that the same material can be used for the insulating layer125, the mask layer118R, the mask layer118G, and the mask layer118B. In this case, the boundary between the insulating layer125and any of the mask layer118R, the mask layer118G, and the mask layer118B and thus the layers cannot be distinguished from each other in some cases. Thus, the insulating layer125and any of the mask layer118R, the mask layer118G, and the mask layer118B are observed as one layer in some cases. In other words, it sometimes appears that one layer is provided in contact with the side surfaces and part of the upper surfaces of the EL layer113R, the EL layer113G, and the EL layer113B, and the insulating layer127covers at least part of the side surface of the one layer.

The insulating layer127provided over the insulating layer125has a planarization function for the extreme unevenness of the insulating layer125, which is formed between adjacent light-emitting elements130. In other words, the insulating layer127has an effect of improving the planarity of the surface where the common electrode115is formed.

As the insulating layer127, an insulating layer containing an organic material can be suitably used. As the organic material, a photosensitive material, for example, a photosensitive organic resin is preferably used, and a photosensitive resin composition containing an acrylic resin is preferably used. Note that in this specification and the like, an acrylic resin refers to not only a polymethacrylic acid ester or a methacrylic resin, but also all the acrylic polymer in a broad sense in some cases.

For the insulating layer127, an acrylic resin, a polyimide resin, an epoxy resin, an imide resin, a polyamide resin, a polyimide-amide resin, a silicone resin, a siloxane resin, a benzocyclobutene-based resin, a phenol resin, precursors of these resins, or the like may be used. For the insulating layer127, an organic material such as polyvinyl alcohol (PVA), polyvinyl butyral, polyvinylpyrrolidone, polyethylene glycol, polyglycerin, pullulan, water-soluble cellulose, or an alcohol-soluble polyamide resin may be used. A photoresist may be used for the photosensitive resin. As the photosensitive organic resin, either a positive-type material or a negative-type material may be used.

A material absorbing visible light may be used for the insulating layer127. When the insulating layer127absorbs light emitted from the light-emitting element130, leakage of light from the light-emitting element130to the adjacent light-emitting element130through the insulating layer127(stray light) can be inhibited. Thus, the display quality of the display device can be improved. Since the display quality of the display device can be improved without using a polarizing plate, the weight and thickness of the display device can be reduced.

Examples of the material absorbing visible light include materials containing pigment of black or the like, materials containing dye, light-absorbing resin materials such as polyimide, and a resin material that can be used for coloring layers. Using a resin material obtained by stacking or mixing color filter materials of two or three or more colors is particularly preferred to enhance the effect of blocking visible light. In particular, mixing color filter materials of three or more colors enables the formation of a black or nearly black resin layer.

The material used for the insulating layer127preferably has a low volume shrinkage rate. In this case, the insulating layer127can be easily formed into a desired shape. In addition, the insulating layer127preferably has a low volume shrinkage rate after being cured. In this case, the shape of the insulating layer127can be easily maintained in a variety of steps after formation of the insulating layer127. Specifically, the volume shrinkage rate of the insulating layer127after thermal curing, after light curing, or after light curing and thermal curing is preferably lower than or equal to 10%, further preferably lower than or equal to 5%, still further preferably lower than or equal to 1%. Here, as the volume shrinkage rate, one of the rate of volume shrinkage by light irradiation and the rate of volume shrinkage by heating, or the sum of these rates can be used.

Providing the protective layer131over the light-emitting elements130can improve the reliability of the light-emitting elements130. The protective layer131may have a single-layer structure or a stacked-layer structure of two or more layers.

There is no limitation on the conductivity of the protective layer131. As the protective layer131, at least one of an insulating film, a semiconductor film, and a conductive film can be used.

As the protective layer131, an inorganic insulating film such as an oxide insulating film, a nitride insulating film, an oxynitride insulating film, or a nitride oxide insulating film can be used, for example. Specific examples of these inorganic films are as listed in the description of the insulating layer125. In particular, the protective layer131preferably includes a nitride insulating film or a nitride oxide insulating film, and further preferably includes a nitride insulating film.

As the protective layer131, an inorganic film containing In—Sn oxide (also referred to as ITO), In—Zn oxide, Ga—Zn oxide, Al—Zn oxide, indium gallium zinc oxide (In—Ga—Zn oxide, also referred to as IGZO), or the like can also be used. The inorganic film preferably has high resistance, specifically, higher resistance than the common electrode115. The inorganic film may further contain nitrogen.

By including the inorganic film, the protective layer131can inhibit oxidation of the common electrode115. Moreover, by including the inorganic film, the protective layer131can inhibit entry of impurities such as water and oxygen into the light-emitting element130. Accordingly, since the light-emitting element130can be a light-emitting element that is unlikely to deteriorate, the display device100can be a highly reliable display device.

When light emitted from the light-emitting element130is extracted through the protective layer131, the protective layer131preferably has a high visible-light-transmitting property. For example, ITO, IGZO, and aluminum oxide are preferable because they are inorganic materials having a high visible-light-transmitting property.

The protective layer131can employ, for example, a stacked-layer structure of an aluminum oxide film and a silicon nitride film over the aluminum oxide film, or a stacked-layer structure of an aluminum oxide film and an IGZO film over the aluminum oxide film. Such a stacked-layer structure can inhibit entry of impurities such as water and oxygen into the EL layer113side.

Furthermore, the protective layer131may include an organic film. For example, the protective layer131may include both an organic film and an inorganic film. Examples of an organic material that can be used for the protective layer131include organic insulating materials that can be used for the insulating layer127.

The protective layer131may have a stacked-layer structure of two layers which are formed by different film formation methods. Specifically, the first layer of the protective layer131may be formed by an ALD method, and the second layer of the protective layer131may be formed by a sputtering method.

A light-blocking layer may be provided on a surface of the substrate120on the resin layer122side. Moreover, a variety of optical members can be provided on the outer surface of the substrate120. Examples of the optical members include a polarizing plate, a retardation plate, a light diffusion layer such as a diffusion film, an anti-reflective layer, and a light-condensing film. Furthermore, an antistatic film inhibiting the attachment of dust, a water repellent film inhibiting the attachment of stain, a hard coat film inhibiting generation of a scratch caused by the use, an impact-absorbing layer, or the like may be provided as a surface protective layer on the outer surface of the substrate120. For example, a glass layer or a silica layer (SiOxlayer) is preferably provided as the surface protective layer to inhibit the surface contamination and generation of a scratch. The surface protective layer may be formed using DLC (diamond like carbon), aluminum oxide (AlOx), a polyester-based material, a polycarbonate-based material, or the like. For the surface protective layer, a material having high visible-light transmittance is preferably used. The surface protective layer is preferably formed using a material with high hardness.

For the substrate120, glass, quartz, ceramic, sapphire, a resin, a metal, an alloy, a semiconductor, or the like can be used. The substrate on the side from which light from the light-emitting element is extracted is formed using a material that transmits the light. When the substrate120is formed using a flexible material, the flexibility of the display device can be increased. Furthermore, a polarizing plate may be used as the substrate120.

For the substrate120, any of the following can be used: polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), a polyacrylonitrile resin, an acrylic resin, a polyimide resin, a polymethyl methacrylate resin, a polycarbonate (PC) resin, a polyethersulfone (PES) resin, polyamide resins (e.g., nylon and aramid), a polysiloxane resin, a cycloolefin resin, a polystyrene resin, a polyamide-imide resin, a polyurethane resin, a polyvinyl chloride resin, a polyvinylidene chloride resin, a polypropylene resin, a polytetrafluoroethylene (PTFE) resin, an ABS resin, and cellulose nanofiber. Glass that is thin enough to have flexibility may be used for the substrate120.

In the case where a circularly polarizing plate overlaps with the display device, a highly optically isotropic substrate is preferably used as the substrate included in the display device. A highly optically isotropic substrate has a low birefringence, or more specifically a small amount of birefringence.

The absolute value of a retardation (phase difference) of a highly optically isotropic substrate is preferably less than or equal to 30 nm, further preferably less than or equal to 20 nm, still further preferably less than or equal to 10 nm.

Examples of the film having high optical isotropy include a triacetyl cellulose (TAC, also referred to as cellulose triacetate) film, a cycloolefin polymer (COP) film, a cycloolefin copolymer (COC) film, and an acrylic film.

When a film is used for the substrate and the film absorbs water, the shape of the display device might be changed, e.g., creases are generated. Thus, for the substrate, a film with a low water absorption rate is preferably used. For example, a film with a water absorption rate lower than or equal to 1% is preferably used, a film with a water absorption rate lower than or equal to 0.1% is further preferably used, and a film with a water absorption rate lower than or equal to 0.01% is still further preferably used.

As the resin layer122, any of a variety of curable adhesives such as a reactive curable adhesive, a thermosetting curable adhesive, an anaerobic adhesive, and a photocurable adhesive such as an ultraviolet curable adhesive can be used. Examples of these adhesives include an epoxy resin, an acrylic resin, a silicone resin, a phenol resin, a polyimide resin, an imide resin, a PVC (polyvinyl chloride) resin, a PVB (polyvinyl butyral) resin, and an EVA (ethylene vinyl acetate) resin. In particular, a material with low moisture permeability, such as an epoxy resin, is preferred. A two-component-mixture-type resin may be used. An adhesive sheet may be used, for example.

FIG.2B1is a cross-sectional view illustrating a structure example of the conductive layer111and the conductive layer112. Note that FIG.2B1also illustrates the insulating layer105. The same applies to other views illustrating a structure example of the conductive layer111and the conductive layer112.

As illustrated in FIG.2B1, the conductive layer111can be configured to include a conductive layer111aover the insulating layer105, a conductive layer111bover the conductive layer111a, and a conductive layer111cover the conductive layer111b. The conductive layer112is provided to cover an upper surface of the conductive layer111c, a side surface of the conductive layer111c, a side surface of the conductive layer111b, and a side surface of the conductive layer111a.

In the example illustrated in FIG.2B1, the conductive layer111bis interposed between the conductive layer111aand the conductive layer111c. A material that is less likely to change in quality than the conductive layer111bis preferably used for the conductive layer111aand the conductive layer111c. For example, a material that is less likely to cause migration due to contact with the insulating layer105than the conductive layer111bcan be used for the conductive layer111a. For the conductive layer111c, a material which is less likely to be oxidized than the conductive layer111band an oxide of which has lower electrical resistance than an oxide of the material used for the conductive layer111bcan be used.

In this specification and the like, migration refers to one or both of stress migration and electromigration. Stress migration refers to a phenomenon in which, in heat treatment, a stress occurs in the conductive layer due to a difference in thermal expansion coefficient between a conductive layer and a layer such as an insulating layer in contact with the conductive layer to cause atoms included in the conductive layer to migrate. Electromigration refers to a phenomenon in which an electric field causes atoms included in the conductive layer to migrate. Migration might form hillocks which are bulges or voids which are cavities on a surface of the conductive layer. The hillock formation might cause a short circuit between the conductive layer and another conductive layer, and the void formation might break the conductive layer.

In this manner, the structure in which the conductive layer111bis interposed between the conductive layer111aand the conductive layer111ccan expand the range of choices for the material for the conductive layer111b. The conductive layer111b, for example, can thus have higher visible light reflectance than at least one of the conductive layer111aand the conductive layer111c. For example, aluminum can be used for the conductive layer111b. Note that an alloy containing aluminum may be used for the conductive layer111b. For the conductive layer111a, titanium, a material which has lower visible light reflectance than aluminum and is less likely to cause migration even at the time of contact with the insulating layer105than aluminum, can be used. For the conductive layer111c, titanium, a material which has lower visible light reflectance than aluminum and is less likely to be oxidized than aluminum and whose oxide has lower electrical resistivity than aluminum oxide, can be used.

The conductive layer111having a stacked-layer structure of a plurality of layers as described above can improve the characteristics of the display device. For example, the display device100can have high light extraction efficiency and high reliability.

FIG.2B2illustrates a modification example of the structure in FIG.2B1. In this example, the conductive layer112includes a conductive layer112a, which covers the upper surface of the conductive layer111c, the side surface of the conductive layer111c, the side surface of the conductive layer111b, and the side surface of the conductive layer111a, and a conductive layer112bover the conductive layer112a.

For the conductive layer112a, a material similar to the material that can be used for the conductive layer111ccan be used. For the conductive layer112b, a material similar to the material that can be used for the conductive layer112illustrated in FIG.2B1can be used. In other words, for example, a metal material such as titanium can be used for the conductive layer112a, and for example, a conductive oxide such as indium tin oxide can be used for the conductive layer112b.

The conductive layer112that has the structure illustrated in FIG.2B2can hinder the conductive layer112b, for which a conductive oxide such as indium tin oxide can be used, from being in contact with the side surface of the conductive layer111b, for which aluminum can be used, for example. Consequently, a change in the quality of the conductive layer111bcan be suitably inhibited, and the reliability of the display device100can be increased. Note that the conductive layer111cis preferably provided even in the case where the conductive layer112has the structure illustrated in FIG.2B2. This can inhibit oxygen in the atmosphere from oxidizing, for example, the upper surface of the conductive layer111bhaving higher visible light reflectance than the conductive layer111aafter the formation of the conductive layer111but before the formation of the conductive layer112. Thus, a reduction in the visible light reflectance of the conductive layer111can be inhibited. Consequently, the display device100can be a display device having high light extraction efficiency.

In the case where the conductive layer112has a stacked-layer structure of the conductive layer112aand the conductive layer112b, as illustrated in FIG.2B2, for example, a conductive oxide such as indium tin oxide may be used for the conductive layer112aand a mixed material in which molybdenum oxide and an organic material are mixed may be used for the conductive layer112b.

In the case where the conductive layer111has the structure illustrated in FIG.2B1and FIG.2B2, for example, an end portion of the conductive layer111bmight be positioned more inside than an end portion of the conductive layer111cin a cross-sectional view. In other words, the conductive layer111cincludes a region projecting from the conductive layer111bin a cross-sectional view in some cases. In this case, when the conductive layer112is formed by a film formation method providing low coverage, the above projecting region might cause step disconnection of the conductive layer112. The conductive layer112might be locally thinned to have increased electrical resistance.

Thus, when the conductive layer112is formed by a film formation method providing high coverage, it is possible to inhibit the occurrence of a connection defect due to the step disconnection of the conductive layer112and an increase in electrical resistance due to the local thinning of the conductive layer112. For example, when the conductive layer112is formed by an ALD method, even with the conductive layer111cincluding a region projecting from the conductive layer111b, the occurrence of a connection defect due to the step disconnection of the conductive layer112and an increase in electrical resistance due to the local thinning of the conductive layer112can be suitably inhibited.

FIG.3Ais a cross-sectional view of a structure example of the conductive layer111and the conductive layer112, which is different from the structures in FIG.2B1and FIG.2B2. As illustrated inFIG.3A, the conductive layer111can be configured to include the conductive layer111aover the insulating layer105and the conductive layer111bover the conductive layer111a. In other words, the conductive layer111illustrated inFIG.3Ahas a stacked-layer structure of two layers. In the case where the conductive layer111has a stacked-layer structure of a plurality of layers as described above, the visible light reflectance of at least one of the layers included in the conductive layer111is higher than that of the conductive layer112. The conductive layer112is provided to cover the side surfaces and upper surfaces of the conductive layer111aand the conductive layer111b.

As already described above, the conductive layer111preferably has a side surface with a tapered shape. Specifically, the side surface of the conductive layer111preferably has a tapered shape with a taper angle of less than 90°. For example, in the conductive layer111illustrated inFIG.3A, the side surface of at least one of the conductive layer111aand the conductive layer111bpreferably has a tapered shape. For example, the conductive layer111apreferably has a side surface with a tapered shape. Alternatively, each of the side surface of the conductive layer111aand the side surface of the conductive layer111bpreferably has a tapered shape.

FIG.3Billustrates a modification example of the structure inFIG.3A, and in this example, the conductive layer112has a two-layer structure in which the conductive layer112aand the conductive layer112bover the conductive layer112aare stacked. For the conductive layer112a, a material similar to the material that can be used for the conductive layer111can be used. For the conductive layer112b, a material similar to the material that can be used for the conductive layer112illustrated inFIG.3Acan be used, for example.

For the conductive layer112a, silver or an alloy containing silver can be used, for example. Silver and an alloy containing silver have higher visible light reflectance than that of titanium. In addition, silver is less likely to be oxidized than aluminum, which can be used for the conductive layer111b, and silver oxide has lower electrical resistance than aluminum oxide, for example. Thus, the use of silver or an alloy containing silver for the conductive layer112acan suitably increase the visible light reflectance of the pixel electrode and inhibit an increase in the electrical resistance of the pixel electrode due to oxidation of the conductive layer112a. Accordingly, the display device100can have high light extraction efficiency and high reliability. In particular, in the case where the light-emitting element130has a microcavity structure, silver or an alloy containing silver, which is a material having high visible light reflectance, is preferably used for the conductive layer112a. This can suitably increase the light extraction efficiency of the display device100.

Titanium may be used for the conductive layer112a. Since titanium has better processability in etching than silver, the use of titanium for the conductive layer112afacilitates the formation of the conductive layer112a.

Note that the conductive layer111does not necessarily include the conductive layer111b. That is, the conductive layer111can have a single-layer structure of the conductive layer111a. For example, titanium which can be used for the conductive layer111ais less likely to be oxidized which aluminum that can be used for the conductive layer111b, and the electrical resistivity of titanium oxide is lower than the electrical resistivity of aluminum oxide. This indicates that, when the conductive layer111does not include the conductive layer111b, the electrical resistance at the contact interface between the conductive layer111and the conductive layer112can be reduced.

FIG.4Ais a cross-sectional view of a structure example of the conductive layer111and the conductive layer112, which is different from the structures in FIG.2B1, FIG.2B2,FIG.3A, andFIG.3B. In the example illustrated inFIG.4A, the conductive layer111has a single-layer structure. The conductive layer112has a stacked-layer of three layers, the conductive layer112a, the conductive layer112bover the conductive layer112a, and a conductive layer112cover the conductive layer112b.

For the conductive layer111illustrated inFIG.4A, for example, a material that is hardly oxidized when being in contact with the conductive layer112aand has electrical resistivity unlikely to increase significantly even when being oxidized is used. For example, the conductive layer111can be formed using an alloy containing titanium. Thus, any change in the quality of the conductive layer111can be inhibited and the display device100can be a highly reliable display device.

The conductive layer112aillustrated inFIG.4Ahas higher adhesion to the conductive layer112bthan the insulating layer105does, for example. For the conductive layer112a, a conductive oxide can be used, and an oxide containing one or more selected from indium, tin, zinc, gallium, titanium, aluminum, and silicon, for example, can be used. Specifically, indium tin oxide or indium tin oxide containing silicon, for example, can be used for the conductive layer112a. This can inhibit peeling of the conductive layer112b, so that the display device100can be a highly reliable display device. The structure can be employed in which the conductive layer112ais in contact with the insulating layer105and the conductive layer112bis not in contact with the insulating layer105, as illustrated inFIG.4A.

The conductive layer112billustrated inFIG.4Ais a layer having higher visible light reflectance than the conductive layer111, the conductive layer112a, and the conductive layer112c. The visible light reflectance of the conductive layer112bcan be, for example, higher than or equal to 70% and lower than or equal to 100%, and is preferably higher than or equal to 80% and lower than or equal to 100%, further preferably higher than or equal to 90% and lower than or equal to 100%. For the conductive layer112b, silver or an alloy containing silver can be used, for example. An example of the alloy containing silver is APC. Consequently, the display device100can be a display device with high light extraction efficiency.

In the case where the conductive layer111and the conductive layer112function as the anode, a layer having a high work function is used as the conductive layer112c. The conductive layer112chas a higher work function than the conductive layer112b, for example. Accordingly, the driving voltage of the light-emitting element130can be reduced. For the conductive layer112c, a material similar to the material that can be used for the conductive layer112acan be used, for example. For example, the conductive layer112aand the conductive layer112ccan be formed using the same kind of material. For example, in the case where indium tin oxide is used for the conductive layer112a, indium tin oxide can also be used for the conductive layer112c.

In the case where the conductive layer111and the conductive layer112function as the cathode, a layer having a low work function is used as the conductive layer112c. The conductive layer112chas a lower work function than the conductive layer112b, for example. Accordingly, the driving voltage of the light-emitting element130can be reduced.

The conductive layer112cis preferably a layer having high visible light transmittance. For example, the visible light transmittance of the conductive layer112cis preferably higher than those of the conductive layer111and the conductive layer112b. The visible light transmittance of the conductive layer112ccan be, for example, greater than or equal to 60% and less than or equal to 100%, and is preferably higher than or equal to 70% and lower than or equal to 100%, further preferably higher than or equal to 80% and lower than or equal to 100%. Accordingly, the amount of light absorbed by the conductive layer112camong light emitted from the EL layer113can be reduced. As described above, the conductive layer112bunder the conductive layer112ccan be a layer having high visible light reflectance. Thus, the display device100can have high light extraction efficiency.

Note that the conductive layer112billustrated inFIG.4Ais a layer having high reflectance with respect to light emitted from the EL layer113, and the conductive layer112cis a layer having high transmittance with respect to light emitted from the EL layer113. For example, in the case where the EL layer113emits infrared light, the conductive layer112bis a layer having high reflectance with respect to infrared light, and the conductive layer112cis a layer having high transmittance with respect to infrared light. For example, in the case where the EL layer113emits infrared light, “visible light” in the above description of the conductive layer112band the conductive layer112cillustrated inFIG.4Acan be replaced with “infrared light.”

Thus, the display device100can have high reliability and high light extraction efficiency. In addition, the display device100can include a light-emitting element with high emission efficiency.

FIG.4BandFIG.4Care each a cross-sectional view of a structure example of the conductive layer111and the conductive layer112, which is different from the structure inFIG.4A. In the example illustrated inFIG.4B, the conductive layer111has a stacked-layer of two layers, the conductive layer111aand the conductive layer111bover the conductive layer111a. In the example illustrated inFIG.4C, the conductive layer111has a stacked-layer of three layers, the conductive layer111a, the conductive layer111bover the conductive layer111a, and the conductive layer111cover the conductive layer111b.

The conductive layer111aand the conductive layer111ccan be formed using a material similar to that for the conductive layer111illustrated inFIG.4A, for example, titanium or an alloy containing titanium. The conductive layer111bcan be a layer having higher visible light reflectance than the conductive layer111a, for example. Moreover, the conductive layer111bcan be a layer that is more easily processed by etching than the conductive layer112b, for example. In the above manner, the thickness of the conductive layer112bthat can contain silver or an alloy containing silver, for example, can be reduced while the visible light reflectance of the pixel electrode increases. Hence, the display device100can have high light extraction efficiency and be easily manufactured. For the conductive layer111b, aluminum or an aluminum alloy can be used, for example.

Next, a structure of the insulating layer127and the vicinity thereof will be described with reference toFIG.5AandFIG.5B.FIG.5Ais a cross-sectional enlarged view of a region including the insulating layer127between the EL layer113R and the EL layer113G and the vicinity thereof. The description is made below using the insulating layer127between the EL layer113R and the EL layer113G as an example: the same applies to the insulating layer127between the EL layer113G and the EL layer113B and the insulating layer127between the EL layer113B and the EL layer113R, for example.FIG.5Bis an enlarged view of the vicinity of the end portion of the insulating layer127over the EL layer113G illustrated inFIG.5A. Although the description is sometimes made below using the end portion of the insulating layer127over the EL layer113G as an example, the same applies to the end portion of the insulating layer127over the EL layer113R and the end portion of the insulating layer127over the EL layer113B, for example.

As illustrated inFIG.5A, the EL layer113R is provided to cover the conductive layer112R, and the EL layer113G is provided to cover the conductive layer112G. The mask layer118R is provided in contact with part of the upper surface of the EL layer113R, and the mask layer118G is provided in contact with part of the upper surface of the EL layer113G. The insulating layer125is provided to include a region in contact with the upper surface and the side surface of the mask layer118R, the side surface of the EL layer113R, the upper surface of the insulating layer105, the upper surface and the side surface of the mask layer118G, and the side surface of the EL layer113G. The insulating layer127is provided in contact with the upper surface of the insulating layer125. The insulating layer127overlaps with the side surface and part of the upper surface of the EL layer113R and the side surface and part of the upper surface of the EL layer113G with the insulating layer125therebetween, and is in contact with at least part of the side surface and the upper surface of the insulating layer125. The common layer114is provided to cover the EL layer113R, the mask layer118R, the EL layer113G, the mask layer118G, the insulating layer125, and the insulating layer127. The common electrode115is provided over the common layer114.

As illustrated inFIG.5A, the thickness of the insulating layer105in a region that does not overlap with the EL layer113may be smaller than that of the insulating layer105in a region overlapping with the EL layer113. That is, the insulating layer105may have a depressed portion in the region that does not overlap with the EL layer113. The depressed portion is formed because of the step of forming the EL layer113, for example.

The insulating layer127is formed in a region between the two island-shaped EL layers113(e.g., a region between the EL layer113R and the EL layer113G inFIG.5A). In this case, at least part of the insulating layer127is positioned between a side end portion of one of the EL layers113(e.g., the EL layer113R inFIG.5A) and a side end portion of the other EL layer113(e.g., the EL layer113G inFIG.5A). Providing the insulating layer127in such a manner can inhibit formation of a disconnected portion and a locally thinned portion in the common layer114and the common electrode115that are formed over the island-shaped EL layers113and over the insulating layer127.

As illustrated inFIG.5B, the end portion of the insulating layer127preferably has a tapered shape with a taper angle θ1 in the cross-sectional view of the display device100. The taper angle θ1 is an angle formed by the side surface of the insulating layer127and the substrate surface. Note that the taper angle θ1 may be an angle formed by the side surface of the insulating layer127and, instead of the substrate surface, the upper surface of the flat portion of the EL layer113G or the upper surface of the flat portion of the conductive layer112G.

The taper angle θ1 of the insulating layer127is less than 90°, preferably less than or equal to 60°, further preferably less than or equal to 45°, still further preferably less than or equal to 20°. When the end portion of the insulating layer127has such a forward tapered shape, the common layer114and the common electrode115that are provided over the insulating layer127can be formed with favorable coverage, thereby inhibiting step disconnection, local thinning, or the like. Accordingly, the in-place uniformity of the common layer114and the common electrode115can be improved, leading to higher display quality of the display device.

As illustrated inFIG.5A, the upper surface of the insulating layer127preferably has a convex shape in the cross-sectional view of the display device100. The convex shape of the upper surface of the insulating layer127is preferably a shape gently bulging toward the center. The insulating layer127preferably has a shape such that the convex portion at the center portion of the upper surface is connected smoothly to the tapered portion of the end portion. When the insulating layer127has such a shape, the common layer114and the common electrode115can be formed with good coverage over the whole insulating layer127.

As illustrated inFIG.5B, the end portion of the insulating layer127is preferably positioned on the outer side of the end portion of the insulating layer125. In that case, unevenness of the surface where the common layer114and the common electrode115are formed is favorably reduced, and coverage with the common layer114and the common electrode115can be improved.

As illustrated inFIG.5B, the end portion of the insulating layer125preferably has a tapered shape with a taper angle θ2 in the cross-sectional view of the display device100. The taper angle θ2 is an angle formed by the side surface of the insulating layer125and the substrate surface. Note that the taper angle θ2 may be an angle formed by the side surface of the insulating layer125and, instead of the substrate surface, the upper surface of the flat portion of the EL layer113G or the upper surface of the flat portion of the conductive layer112G.

The taper angle θ2 of the insulating layer125is less than 90°, preferably less than or equal to 60°, further preferably less than or equal to 45°, still further preferably less than or equal to 20°.

As illustrated inFIG.5B, the end portion of the mask layer118G preferably has a tapered shape with a taper angle θ3 in the cross-sectional view of the display device100. The taper angle θ3 is an angle formed by the side surface of the mask layer118G and the substrate surface. Note that the taper angle θ3 may be an angle formed by the side surface of the mask layer118G and, instead of the substrate surface, the upper surface of the flat portion of the EL layer113G or the upper surface of the flat portion of the conductive layer112G.

The taper angle θ3 of the mask layer118G is less than 90°, preferably less than or equal to 60°, further preferably less than or equal to 45°, still further preferably less than or equal to 20°. When the end portion of the mask layer118G has such a forward tapered shape, the common layer114and the common electrode115that are provided over the mask layer118G can be formed with favorable coverage.

The end portion of the mask layer118R and the end portion of the mask layer118G are preferably positioned on the outer side of the end portion of the insulating layer125. In that case, unevenness of the surface where the common layer114and the common electrode115are formed is reduced, and coverage with the common layer114and the common electrode115can be improved.

Although the details will be described later, when the insulating layer125and the mask layer118are etched at once, the insulating layer125and the mask layer118under the end portion of the insulating layer127are eliminated by side etching and accordingly a cavity is formed in some cases. The cavity causes unevenness in the formation surface of the common layer114and the common electrode115, so that step disconnection is likely to occur in the common layer114and the common electrode115. Thus, when etching treatment is divided into two steps and heat treatment is performed between the two etching steps, even if a cavity is formed by the first etching treatment, the shape of the insulating layer127is changed by the heat treatment to fill the cavity. Since the second etching treatment is for etching a thinner film, the amount of side etching decreases, a cavity is less likely to be formed, and even if a cavity is formed, it can be extremely small. Thus, generation of unevenness in the formation surface of the common layer114and the common electrode115can be inhibited and accordingly step disconnection of the common layer114and the common electrode115can be inhibited. Since the etching treatment is performed twice, the taper angle θ2 and the taper angle θ3 are different from each other in some cases. The taper angle θ2 and the taper angle θ3 may be the same. The taper angle θ2 and the taper angle θ3 may each be smaller than the taper angle θ1.

The insulating layer127may cover at least part of the side surface of the mask layer118R and at least part of the side surface of the mask layer118G. For example,FIG.5Billustrates an example in which the insulating layer127touches and covers an inclined surface that is formed by the first etching treatment and positioned at the end portion of the mask layer118G, and an inclined surface that is formed by the second etching treatment and positioned at the end portion of the mask layer118G is exposed. These two inclined surfaces can sometimes be distinguished from each other because of different taper angles. In some cases, they cannot be distinguished from each other because the taper angles on the side surface formed by the two etching treatments are almost the same.

FIG.6AandFIG.6Billustrate a modification example of the structure inFIG.5AandFIG.5B, and in this example, the insulating layer127covers the entire side surface of the mask layer118R and the entire side surface of the mask layer118G. Specifically, inFIG.6B, the insulating layer127covers and is in contact with both of the two inclined surfaces. This is preferable because unevenness of the formation surface of the common layer114and the common electrode115can be further reduced.FIG.6Billustrates an example where the end portion of the insulating layer127is positioned on the outer side of the end portion of the mask layer118G. As illustrated inFIG.6B, the end portion of the insulating layer127may be positioned on the inner side of the end portion of the mask layer118G, or may be aligned or substantially aligned with the end portion of the mask layer118G. As illustrated inFIG.6B, the insulating layer127is in contact with the EL layer113G in some cases.

FIG.7AandFIG.8Aillustrate modification examples of the structure illustrated inFIG.5A, andFIG.7BandFIG.8Billustrate modification examples of the structure illustrated inFIG.5B.FIG.7A,FIG.7B,FIG.8A, andFIG.8Billustrate examples where the side surface of the insulating layer127has a concave shape (also referred to as a narrowed portion, a depressed portion, a dent, a hollow, or the like). In some cases, the side surface of the insulating layer127has a concave shape depending on the material and formation conditions (e.g., heating temperature, heating time, and heating atmosphere) of the insulating layer127.

FIG.7AandFIG.7Billustrate an example in which the insulating layer127covers part of the side surface of the mask layer118G and the other part of the side surface of the mask layer118G is exposed.FIG.8AandFIG.8Billustrate an example where the insulating layer127covers and is in contact with the entire side surface of the mask layer118G.

Also in the structures illustrated inFIG.6B,FIG.7B, andFIG.8B, the taper angle θ1 to the taper angle θ3 are preferably within the above range.

As illustrated inFIG.5A,FIG.6A,FIG.7A, andFIG.8A, one end portion of the insulating layer127preferably overlaps with the upper surface of the conductive layer111R and the other end portion of the insulating layer127preferably overlaps with the upper surface of the conductive layer111G. With such a structure, the end portions of the insulating layer127can be formed over substantially flat regions of the EL layer113R and the EL layer113G. This makes it relatively easy to form a tapered shape in each of the insulating layer127, the insulating layer125, and the mask layer118. Furthermore, peeling of the conductive layer111R, the conductive layer111G, the conductive layer112R, the conductive layer112G, the EL layer113R, and the EL layer113G can be inhibited. Meanwhile, a portion where the upper surface of the pixel electrode and the insulating layer127overlap with each other is preferably smaller because the light-emitting region of the light-emitting element can be wider and the aperture ratio can be higher.

As described above, in each of the structures illustrated inFIG.5toFIG.8, the insulating layer127, the insulating layer125, the mask layer118R, and the mask layer118G are provided and thus, the common layer114and the common electrode115can be formed with favorable coverage from the flat or substantially flat region of the EL layer113R to the flat or substantially flat region of the EL layer113G. Moreover, formation of a step disconnection portion and a local thinning portion can be inhibited in the common layer114and the common electrode115. This can inhibit the common layer114and the common electrode115between light-emitting elements130from having connection defects due to the disconnected portion and an increased electrical resistance due to the locally thinned portion. Accordingly: the display device100can be a display20) device with high display quality.

FIG.9AandFIG.9Billustrate modification examples of the structure illustrated inFIG.5A. In the example illustrated inFIG.9A, a side surface of the insulating layer105(a portion surrounded by the dashed line inFIG.9A) is vertical: specifically, the side surface of the insulating layer105at the boundary between a region overlapping with the conductive layer111and a region not overlapping with the conductive layer111is vertical. In the example illustrated inFIG.9B, the upper surface of the insulating layer127has a depressed portion in the center and its vicinity. i.e., has a concave surface in the cross-sectional view. With the structure where the center portion of the insulating layer127has a concave surface, as illustrated inFIG.9B, stress on the insulating layer127can be relieved. Specifically, with the structure where the center portion of the insulating layer127has a concave surface, local stress applied to the end portion of the insulating layer127can be relieved, thereby inhibiting any one or more of peeling between the EL layer113R and the mask layer118R and between the EL layer113G and the mask layer118G, peeling between the EL layer118R and the insulating layer125and between the EL layer118G and the insulating layer125, and peeling between the insulating layer125and the insulating layer127.

In order to form the structure where the center portion of the insulating layer127has a concave surface as illustrated inFIG.9B, light exposure using a multi-tone mask, typically, a half-tone mask or a gray-tone mask, can be performed. Note that a multi-tone mask is a mask capable of light exposure of three levels to provide an exposed portion, a half-exposed portion, and an unexposed portion, and is a light-exposure mask through which light is transmitted to have a plurality of intensities. The insulating layer127including regions with a plurality of (typically two kinds of) thicknesses can be formed with one photomask (one-time light exposure and development process). Alternatively, in order to form the structure where the center portion of the insulating layer127has a concave surface, the line width of the mask positioned on the concave surface is made smaller than the line width of the exposed portion, whereby the insulating layer127including regions with a plurality of thicknesses can be formed.

Note that a method of forming the structure where the center portion of the insulating layer127has a concave surface is not limited to the above. For example, an exposed portion and a half-exposed portion may be formed separately with the use of two photomasks. Alternatively, the viscosity of the resin material used for the insulating layer127may be adjusted, specifically to less than or equal to 10 cP, preferably greater than or equal to 1 cP and less than or equal to 5 cP.

Although not illustrated inFIG.9B, the concave surface in the center portion of the insulating layer127is not necessarily continuous and may be disconnected between adjacent light-emitting elements. This leads to the structure where, in the center portion of the insulating layer127illustrated inFIG.9B, part of the insulating layer127is eliminated to expose the surface of the insulating layer125. In the case of the structure, the insulating layer127can be shaped so as to be covered with the common layer114and the common electrode115.

Structure Example 2

FIG.10is a modification example of the structure illustrated inFIG.2A: in this example, the end portion of the mask layer118R is aligned or substantially aligned with the end portion of the conductive layer112R in addition to the end portion of the EL layer113R. That is,FIG.10illustrates an example in which the end portion of the conductive layer112R is aligned or substantially aligned with the end portion of the EL layer113R. Similarly, in the example illustrated inFIG.10, the end portion of the mask layer118G is aligned or substantially aligned with the end portion of the conductive layer112G in addition to the end portion of the EL layer113G, and the end portion of the mask layer118B is aligned or substantially aligned with the end portion of the conductive layer112B in addition to the end portion of the EL layer113B. That is, in the example illustrated inFIG.10, the end portion of the conductive layer112G is aligned or substantially aligned with the end portion of the EL layer113G, and the end portion of the conductive layer112B is aligned or substantially aligned with the end portion of the EL layer113B. In the example illustrated inFIG.10, the insulating layer125includes regions in contact with the side surface of the conductive layer112R, the side surface of the conductive layer112G, and the side surface of the conductive layer112B, in addition to the side surface of the EL layer113R, the side surface of the EL layer113G, and the side surface of the EL layer113B.

FIG.11Ais an enlarged cross-sectional view of a region of the insulating layer127between the EL layer113R and the EL layer113G and its periphery in the structure illustrated inFIG.10, which is a modification example of the structure illustrated inFIG.5A. In the example illustrated inFIG.11A, the EL layer113R is provided over the conductive layer112R, and the EL layer113G is provided over the conductive layer112G.

FIG.11B,FIG.12A,FIG.12B,FIG.13A, andFIG.13Billustrate modification examples of the structures illustrated inFIG.6A,FIG.7A,FIG.8A,FIG.9A, andFIG.9B, respectively, and each employ the structure illustrated inFIG.10.

Structure Example 3

FIG.14is a modification example of the structure illustrated inFIG.2A: in this example, the light-emitting element130employs a tandem structure (a structure including a plurality of light-emitting units). The light-emitting unit includes at least one light-emitting layer. A charge-generation layer is preferably provided between light-emitting units.

FIG.14illustrates a structure example of the light-emitting element130employing a two-unit tandem structure in which two light-emitting units are stacked. InFIG.14, the dashed line in the EL layer113indicates the charge-generation layer. Note that also in the following diagrams, the charge-generation layer included in the EL layer113is sometimes indicated by a dashed line.

In the example illustrated inFIG.14, the EL layer113includes a first light-emitting unit below the charge-generation layer and a second light-emitting unit above the charge-generation layer. When the light-emitting element130has a tandem structure, the current efficiency for light emission can be increased, so that the light emission efficiency of the light-emitting element130can be increased. Alternatively, the density of current flowing through the light-emitting element130can be reduced at the same luminance; thus, power consumption of the display device100including the light-emitting element130can be reduced. When the light-emitting element130has a tandem structure, the reliability of the light-emitting element130can be increased. Note that the light-emitting element130may employ a tandem structure with three units or more. For example, in the case where the light-emitting element130has a three-unit tandem structure, the EL layer113can have a structure in which a first light-emitting unit, a first charge-generation layer, a second light-emitting unit, a second charge-generation layer, and a third light-emitting unit are stacked in this order from the bottom.

As described above, each of the EL layer113R, the EL layer113G, and the EL layer113B includes at least a light-emitting layer. For example, the first light-emitting unit and the second light-emitting unit included in the EL layer113R each include a light-emitting layer that emits red light. The first light-emitting unit and the second light-emitting unit included in the EL layer113G each include a light-emitting layer that emits green light. For example, the first light-emitting unit and the second light-emitting unit included in the EL layer113B each include a light-emitting layer that emits blue light.

The light-emitting units included in the EL layer113R, the EL layer113G, and the EL layer113B may each include one or more of a hole-injection layer, a hole-transport layer, a hole-blocking layer, an electron-blocking laver, an electron-transport layer, and an electron-injection layer.

In the pixel108illustrated inFIG.14, in the case where the pixel electrode of the light-emitting element130functions as an anode and the common electrode115functions as a cathode, for example, the first light-emitting unit included in each of the EL layer113R, the EL layer113G, and the EL layer113B may include a hole-injection layer, a hole-transport layer, a light-emitting layer, and an electron-transport layer in this order. In other words, the first light-emitting unit included in the EL layer113can have a structure in which, for example, a first functional layer including a hole-injection layer and a hole-transport layer, a light-emitting layer, and a second functional layer including an electron-transport layer are stacked in order from the bottom. The second light-emitting unit included in each of the EL layer113R, the EL layer113G, and the EL layer113B may include the hole-transport layer, the light-emitting layer, and the electron-transport layer in this order. In other words, the second light-emitting unit included in the EL layer113can have a structure in which, for example, a third functional layer including a hole-transport layer, a light-emitting layer, and a fourth functional layer including an electron-transport layer are stacked in order from the bottom.

Here, the first light-emitting unit and the second light-emitting unit may each include the electron-blocking layer between the hole-transport layer and the light-emitting layer. The hole-blocking layer may be provided between the electron-transport layer and the light-emitting layer. The second light-emitting unit may include the electron-injection layer over the electron-transport layer. Note that the first functional layer may be configured to include one of the hole-injection layer and the hole-transport layer and not to include the other.

In the case where the pixel electrode of the light-emitting element130functions as a cathode and the common electrode115functions as an anode, for example, the first light-emitting unit included in each of the EL layer113R, the EL layer113G, and the EL layer113B may include an electron-injection layer, an electron-transport layer, a light-emitting layer, and a hole-transport layer in this order. In other words, the first light-emitting unit included in the EL layer113can have a structure in which, for example, a first functional layer including an electron-injection layer and an electron-transport layer, a light-emitting layer, and a second functional layer including a hole-transport layer are stacked in order from the bottom. The second light-emitting unit included in each of the EL layer113R, the EL layer113G, and the EL layer113B may include the electron-transport layer, the light-emitting layer, and the hole-transport layer in this order. In other words, the second light-emitting unit included in the EL layer113can have a structure in which, for example, a third functional layer including an electron-transport layer, a light-emitting layer, and a fourth functional layer including a hole-transport layer are stacked in order from the bottom.

Here, the first light-emitting unit and the second light-emitting unit may each include the hole-blocking layer between the electron-transport layer and the light-emitting layer. The electron-blocking layer may be provided between the hole-transport layer and the light-emitting layer. The second light-emitting unit may include the hole-injection layer over the hole-transport layer. Note that the first functional layer may be configured to include one of the electron-injection layer and the electron-transport layer and not to include the other.

In each of the case where the pixel electrode of the light-emitting element130functions as an anode and the case where the pixel electrode of the light-emitting element130functions as a cathode, the first light-emitting unit does not necessarily include the second functional layer. Furthermore, the second light-emitting unit does not necessarily include at least one of the third functional layer and the fourth functional layer.

The second light-emitting unit preferably includes a light-emitting layer and a carrier-transport layer over the light-emitting layer. Alternatively, the second light-emitting unit preferably includes a light-emitting layer and a carrier-blocking layer over the light-emitting layer. Alternatively, the second light-emitting unit preferably includes a light-emitting layer, a carrier-blocking layer over the light-emitting layer, and a carrier-transport layer over the carrier-blocking layer. Since the surface of the second light-emitting unit is exposed in the manufacturing process of the display device, providing one or both of the carrier-transport layer and the carrier-blocking layer over the light-emitting layer inhibits the light-emitting layer from being exposed on the outermost surface, so that damage to the light-emitting layer can be reduced. Accordingly, the reliability of the light-emitting element can be improved. Note that in the case where three or more light-emitting units are provided, the uppermost light-emitting unit preferably includes a light-emitting layer and one or both of a carrier-transport layer and a carrier-blocking layer over the light-emitting layer.

As described above, the light-emitting element130can have a tandem structure. Embodiment 2 can be referred to for the detailed structure of the light-emitting element130having a tandem structure. Furthermore, even when the light-emitting element130has either a single structure or a tandem structure, Embodiment 5 can be referred to for the structure and the material of the light-emitting element130.

FIG.15Ais an enlarged cross-sectional view of a region of the insulating layer127between the EL layer113R and the EL layer113G and its periphery in the structure illustrated inFIG.14, which is a modification example of the structure illustrated inFIG.5A.

In the example illustrated inFIG.15A, the EL layer113R includes a light-emitting unit113R1, a charge-generation layer113R2over the light-emitting unit113R1, and a light-emitting unit113R3over the charge-generation layer113R2, for example. The EL layer113G includes a light-emitting unit113G1, a charge-generation layer113G2over the light-emitting unit113G1, and a light-emitting unit113G3over the charge-generation layer113G2, for example. Here, inFIG.14, a layer indicated by the dashed line in the EL layer113R corresponds to the charge-generation layer113R2and a layer indicated by the dashed line in the EL layer113G corresponds to the charge-generation layer113G2.

In the case where a two-unit tandem structure is employed for the light-emitting element130R and the light-emitting element130G, the light-emitting unit113R1and the light-emitting unit113G1can each be the first light-emitting unit described with reference toFIG.14, and the light-emitting unit113R3and the light-emitting unit113G3can each be the second light-emitting unit described with reference toFIG.14.

FIG.15B,FIG.16A,FIG.16B, andFIG.17Aillustrate modification examples of the structures illustrated inFIG.6A,FIG.7A,FIG.8A, andFIG.9B, respectively, and each employ the structure illustrated inFIG.14.FIG.17Billustrates a modification example of the structure illustrated inFIG.15A, and in this example, the upper surface of the insulating layer127includes a flat portion in a cross-sectional view.

FIG.18Ais a cross-sectional view illustrating a structure example of the region141and the connection portion140. In the region141, the conductive layer109is provided over the insulating layer101, and the insulating layer103is provided over the insulating layer101and over the conductive layer109. The conductive layer109can be formed in the same step as the conductive layer102illustrated inFIG.2Aand contain the same material as the conductive layer102.

In the region141, the EL layer113R over the insulating layer105, the mask layer118R over the insulating layer105and over the EL layer113R, the insulating layer125over the mask layer118R, the insulating layer127over the insulating layer125, the common layer114over the insulating layer127, the common electrode115over the common layer114, the protective layer131over the common electrode115, the resin layer122over the protective layer131, and the substrate120over the resin layer122are provided. In the region141, the mask layer118R is provided so as to cover the end portion of the EL layer113R, for example. Note that in some cases, depending on the manufacturing process of the display device100, for example, the EL layer113G or the EL layer113B is provided in the region141instead of the EL layer113R. In some cases, the mask layer118G or the mask layer118B is provided in the region141instead of the mask layer118R.

The EL layer113R provided in the region141is not electrically connected to the common electrode115. Accordingly, a structure can be employed in which a voltage is not applied to the EL layer113R provided in the region141, which offers a structure in which the EL layer113R provided in the region141does not emit light.

In the display device in which the EL layer113R and the mask layer118R are provided in the region141, it is possible to inhibit the insulating layer105, the insulating layer104, and the insulating layer103from being partly removed by etching or the like during the manufacturing process of the display device and thus inhibit the conductive layer109from being exposed. Hence, the conductive layer109can be inhibited from being unintentionally in contact with other electrodes, layers, or the like. For example, a short circuit between the conductive layer109and the common electrode115can be inhibited. Consequently, the display device100can be a highly reliable display device. Moreover, the display device100can be manufactured by a method with a high yield.

The connection portion140includes the conductive layer111C over the insulating layer105, a conductive layer112C covering the upper surface and the side surface of the conductive layer111C, the common layer114over the conductive layer112C, the common electrode115over the common layer114, the protective layer131over the common electrode115, the resin layer122over the protective layer131, and the substrate120over the resin layer122. The mask layer118R is provided so as to cover an end portion of the conductive layer112C: the insulating layer125, the insulating layer127, the common layer114, the common electrode115, and the protective layer131are stacked in this order over the mask layer118R. In the case where the mask layer118G or the mask layer118B is provided in the region141instead of the mask layer118R, the mask layer118G or the mask layer118B is also provided in the connection portion140instead of the mask layer118R.

In the connection portion140, the conductive layer111C and the conductive layer112C are electrically connected to the common electrode115. The conductive layer111C and the conductive layer112C are electrically connected to, for example, an FPC (Flexible Printed Circuit) (not illustrated). Thus, by supplying a power supply potential to the FPC, for example, the common electrode115can be supplied with the power supply potential through the conductive layer111C and the conductive layer112C.

Here, in the case where the electrical resistance of the common layer114in the thickness direction is small enough to be negligible, electrical continuity between the conductive layer111C, the conductive layer112C, and the common electrode115can be maintained even when the common layer114is provided between the conductive layer112C and the common electrode115. When the common layer114is provided not only in the pixel portion107but also in the region141and the connection portion140, the common layer114can be formed, for example, without using a metal mask such as a mask for specifying a deposition area (also referred to as an area mask, a rough metal mask, or the like to be distinguished from a fine metal mask). Thus, the manufacturing process of the display device100can be simplified.

FIG.18Billustrates a modification example of the structure illustrated inFIG.18A, and in this example, the common layer114is not provided in the connection portion140. In the example illustrated inFIG.18B, the conductive layer112C and the common electrode115can be in contact with each other. Thus, electrical resistance between the conductive layer112C and the common electrode115can be decreased. AlthoughFIG.18Billustrates a structure where in the region141, the common layer114is provided in a region overlapping with the EL layer113R and the common layer114is not provided in a region not overlapping with the EL layer113R, one embodiment of the present invention is not limited thereto. For example, in the region141, it is acceptable that the common layer114is not provided in the region overlapping with the EL layer113R, or the common layer114is provided in the region not overlapping with the EL layer113R.

FIG.18CandFIG.18Dillustrate modification examples of the structures illustrated inFIG.18AandFIG.18B, and in the examples, the conductive layer112C is provided not only in the connection portion140but also in the region141. In the examples illustrated inFIG.18CandFIG.18D, in the region141, the conductive layer112C is provided over the insulating layer105, the EL layer113R is provided over the conductive layer112C, and the mask layer118R is provided over the conductive layer112C and the EL layer113R. In the connection portion140, the mask layer118R is provided over the conductive layer112C.

FIG.18EandFIG.18Fillustrate modification examples of the structures illustrated inFIG.18AandFIG.18B, respectively, and in the examples, the EL layer113R employs a tandem structure.

Structure Example 4

FIG.19Aillustrates a modification example of the structure illustrated inFIG.2A, and in this example, the subpixel110R includes a coloring layer132R, the subpixel110G includes a coloring layer132G, and the subpixel110B includes a coloring layer132B.

As illustrated inFIG.19A, the coloring layer132R, the coloring layer132G, and the coloring layer132B can be provided over the protective layer131. In this case, the protective layer131is preferably planarized but is not necessarily planarized.

In the example illustrated inFIG.19A, the light-emitting element130included in the subpixel110R, the light-emitting element130included in the subpixel110G, and the light-emitting element130included in the subpixel110B can emit light of the same color, e.g., white light. In this case, for example, when the coloring layer132R transmits red light, the coloring layer132G transmits green light, and the coloring layer132B transmits blue light, the display device100having the structure illustrated inFIG.19Acan perform full-color display. Note that the coloring layer132R, the coloring layer132G, or the coloring layer132B may have a function of transmitting cyan light, magenta light, yellow light, white light, infrared light, or the like. The light-emitting element130may emit infrared light, for example.

Since the EL layers113do not have to be formed separately for different emission colors in the display device100having the structure illustrated inFIG.19A, the manufacturing process of the display device100can be simplified. Consequently, the manufacturing cost of the display device100can be reduced, whereby the display device100can be an inexpensive display device.

The adjacent coloring layers132include an overlap region over the insulating layer127. For example, in the cross section illustrated inFIG.19A, one end portion of the coloring layer132G overlaps with the coloring layer132R, and the other end portion of the coloring layer132G overlaps with the coloring layer132B. This can inhibit leakage of light from the light-emitting element130to the adjacent subpixels110. Thus, for example, light emitted from the light-emitting element130provided in the subpixel110G can be inhibited from entering the coloring layer132R and the coloring layer132B. Consequently, the display device100can be a display device with high display quality.

FIG.19Bis a cross-sectional enlarged view of a region including the insulating layer127between the two EL layer113inFIG.19Aand the vicinity thereof. Note thatFIG.19Billustrates the conductive layer112R and the conductive layer112G as the conductive layer112. The shapes of the mask layer118, the insulating layer125, the insulating layer127, and the like illustrated inFIG.19Bare similar to those inFIG.5A.

As illustrated inFIG.19AandFIG.19B, the conductive layer112R, the conductive layer112G, and the conductive layer1112B can differ from each other in thickness. For example, the thickness is preferably set in accordance with the optical path length that intensifies light of the color transmitted through the coloring layer132. For example, in the case where the coloring layer132R transmits red light, the thickness of the conductive layer112R is preferably set to intensify red light: in the case where the coloring layer132G transmits green light, the thickness of the conductive layer112G is preferably set to intensify green light: in the case where the coloring layer132B transmits blue light, the thickness of the conductive layer112B is preferably set to intensify blue light. Thus, a microcavity structure is achieved, and the color purity of light emitted from the subpixels110can be increased. Note that the conductive layer112R, the conductive layer112G, and the conductive layer1112B may differ from each other in thickness also in the structure illustrated inFIG.2A, for example. In that case, a microcavity structure can be achieved even when the EL layer113R, the EL layer113G, and the EL layer113B have the same thickness.

Although the light-emitting element130has a single structure inFIG.19B, the light-emitting element130may have a tandem structure.FIG.20Aillustrates an example in which the EL layer113includes a light-emitting unit113al, a charge-generation layer113b1over the light-emitting unit113al, and a light-emitting unit113c1over the charge-generation layer113bl. The light-emitting element130including the EL layer113illustrated inFIG.20Ahas a two-unit tandem structure. When the light-emitting element130has a tandem structure, the current efficiency for light emission can be increased, so that the light emission efficiency of the light-emitting element130can be increased. Alternatively, the density of current flowing through the light-emitting element130can be reduced at the same luminance: thus, power consumption of the display device100including the light-emitting element130can be reduced. When the light-emitting element130has a tandem structure, the reliability of the light-emitting element130can be increased.

The light-emitting unit113a1and the light-emitting unit113c1each include at least one light-emitting layer. The color of light emitted from the light-emitting unit113a1can be different from the color of light emitted from the light-emitting unit113cl.

In this specification and the like, light emitted from a light-emitting layer included in a light-emitting unit is referred to as light emitted from the light-emitting unit.

The color of light emitted from the light-emitting layer included in the light-emitting unit113a1and the color of light emitted from the light-emitting layer included in the light-emitting unit113c1can be complementary colors, for example. For example, one of the light-emitting unit113a1and the light-emitting unit113c1can emit blue light and the other of the light-emitting unit113a1and the light-emitting unit113c1can emit yellow light. For example, one of the light-emitting unit113a1and the light-emitting unit113c1can be emit blue light and the other of the light-emitting unit113a1and the light-emitting unit113c1can emit red light and green light. For example, when the pixel electrode of the light-emitting element130functions as the anode and the common electrode115functions as the cathode, the light-emitting unit113a1can emit blue light. In that case, the light-emitting element130as a whole can emit white light.

The light-emitting unit113a1and the light-emitting unit113c1may each include one or more of a hole-injection layer, a hole-transport layer, a hole-blocking layer, an electron-blocking layer, an electron-transport layer, and an electron-injection layer in addition to the light-emitting layer. That is, the light-emitting unit113a1and the light-emitting unit113c1may each include a functional layer. A structure similar to the above can be employed for a light-emitting unit other than the light-emitting unit113a1and the light-emitting unit113c1.

For example, in the case where the pixel electrode of the light-emitting element130functions as an anode and the common electrode115functions as a cathode, the light-emitting unit113a1can have a structure in which the first functional layer including the hole-injection layer and the hole-transport layer, the light-emitting layer, and the second functional layer including the electron-transport layer are stacked in this order from the bottom. Furthermore, the light-emitting unit113c1may include a hole-transport layer, the light-emitting layer, and an electron-transport layer in this order. In other words, the light-emitting unit113c1can have a structure in which, for example, the third functional layer including the hole-transport layer, the light-emitting layer, and the fourth functional layer including the electron-transport layer are stacked in order from the bottom.

Here, the light-emitting unit113a1and the light-emitting unit113c1may each include the electron-blocking layer between the hole-transport layer and the light-emitting layer. In addition, the hole-blocking layer may be provided between the electron-transport layer and the light-emitting layer. The light-emitting unit113c1may include the electron-injection layer between the electron-transport layer and the common electrode115. Note that the first functional layer may be configured to include one of the hole-injection layer and the hole-transport layer and not to include the other.

For example, in the case where the pixel electrode of the light-emitting element130functions as a cathode and the common electrode115functions as an anode, the light-emitting unit113a1can have a structure in which the first functional layer including the electron-injection layer and the electron-transport layer, the light-emitting layer, and the second functional layer including the hole-transport layer are stacked in this order from the bottom. Furthermore, the light-emitting unit113c1may include an electron-transport layer, the light-emitting layer, and a hole-transport layer in this order. In other words, the light-emitting unit113c1can have a structure in which, for example, the third functional layer including the electron-transport layer, the light-emitting laver, and the fourth functional layer including the hole-transport layer are stacked in order from the bottom.

Here, the light-emitting unit113a1and the light-emitting unit113c1may each include the hole-blocking layer between the electron-transport layer and the light-emitting layer. In addition, the electron-blocking layer may be provided between the hole-transport layer and the light-emitting layer. The light-emitting unit113c1may include the hole-injection layer between the hole-transport layer and the common electrode115. Note that the first functional layer may be configured to include one of the electron-injection layer and the electron-transport layer and not to include the other.

In each of the case where the pixel electrode of the light-emitting element130functions as an anode and the case where the pixel electrode of the light-emitting element130functions as a cathode, the light-emitting unit113a1does not necessarily include the second functional layer. Furthermore, the light-emitting unit113c1does not necessarily include at least one of the third functional layer and the fourth functional layer.

The charge-generation layer113b1includes at least a charge-generation region. The charge-generation layer113b1has a function of injecting electrons into one of the light-emitting unit113a1and the light-emitting unit113c1and a function of injecting holes into the other of the light-emitting unit113a1and the light-emitting unit113c1when voltage is applied between the pixel electrode of the light-emitting element130and the common electrode115.

FIG.20Billustrates an example in which the EL layer113includes a light-emitting unit113a2, a charge-generation layer113b2over the light-emitting unit113a2, a light-emitting unit113c2over the charge-generation layer113b2, a charge-generation layer113dover the light-emitting unit113c2, and a light-emitting unit113eover the charge-generation layer113d. The light-emitting element130including the EL layer113illustrated inFIG.20Bhas a three-unit tandem structure. By increasing the number of units in the tandem structure, the current efficiency of the light-emitting element130for light emission can be favorably increased, so that the light emission efficiency of the light-emitting element130can be favorably increased. Alternatively, the density of current flowing through the light-emitting element130can be favorably reduced at the same luminance: thus, power consumption of the display device100including the light-emitting element130can be favorably reduced. Thus, the reliability of the light-emitting element130can be suitably increased. Note that the light-emitting element130may have a tandem structure with four or more units.

The light-emitting unit113a2, the light-emitting unit113c2, and the light-emitting unit113eeach include at least one light-emitting layer. The color of light emitted from at least one of the light-emitting unit113a2, the light-emitting unit113c2, and the light-emitting unit113ecan differ from the color(s) of light emitted from the other light-emitting unit(s). For example, the color of light emitted from at least one of the light-emitting unit113a2, the light-emitting unit113c2, and the light-emitting unit113ecan be complementary to the color of light emitted from the other light-emitting unit(s).

For example, the light-emitting unit113a2and the light-emitting unit113ecan emit blue light, and the light-emitting unit113c2can emit yellow, yellow green, or green light. As another example, the light-emitting unit113a2and the light-emitting unit113ecan emit blue light, and the light-emitting unit113c2can emit red light, green light, and yellow green light. Thus, the light-emitting element130as a whole can emit white light.

The charge-generation layer113b2and the charge-generation layer113deach include at least a charge-generation region. The charge-generation layer113b2has a function of injecting electrons into one of the light-emitting unit113a2and the light-emitting unit113c2and a function of injecting holes into the other of the light-emitting unit113a2and the light-emitting unit113c2when voltage is applied between the pixel electrode of the light-emitting element130and the common electrode115. The charge-generation layer113dhas a function of injecting electrons into one of the light-emitting unit113c2and the light-emitting unit113eand a function of injecting holes into the other of the light-emitting unit113c2and the light-emitting unit113ewhen voltage is applied between the pixel electrode of the light-emitting element130and the common electrode115.

FIG.21Aillustrates a modification example of the structure illustrated inFIG.10, and in this example, the subpixel110R includes the coloring layer132R, the subpixel110G includes the coloring layer132G, and the subpixel110B includes the coloring layer132B. That is,FIG.21Aillustrates an example in which the structure example illustrated inFIG.10and the structure example illustrated inFIG.19Aare combined.

FIG.21Bis a cross-sectional enlarged view of a region including the insulating layer127between the two EL layer113inFIG.21Aand the vicinity thereof. Note thatFIG.21Billustrates the conductive layer112R and the conductive layer112G as the conductive layer112. The shapes of the mask layer118, the insulating layer125, the insulating layer127, and the like illustrated inFIG.21Bare similar to those inFIG.11A.

In the display device of one embodiment of the present invention, the island-shaped EL layer is provided in each light-emitting element, whereby generation of lateral leakage current between the subpixels can be inhibited. This can inhibit crosstalk due to unintended light emission, so that a display device with extremely high contrast can be obtained. The insulating layer that has an end portion with a tapered shape and is provided between adjacent island-shaped EL layers can inhibit formation of step disconnection and a locally thinned portion in the common electrode at the time of forming the common electrode. This can inhibit the common layer and the common electrode from having connection defects due to the disconnected portion and an increased electrical resistance due to the locally thinned portion. Consequently, the display device of one embodiment of the present invention achieves both high resolution and high display quality.

Next, the light-emitting region of the display device of one embodiment of the present invention is described with reference to drawings.

Structure Example 5

FIG.22Aillustrates a modification example of the structure illustrated inFIG.19A. Note thatFIG.22Ais a cross-sectional view in which, for example, the microcavity structure described above is omitted and the vicinity of the subpixel110R and the subpixel110G illustrated inFIG.19Ais enlarged.FIG.22Bis a reference view of a cross-section illustrating the light-emitting region of the display device. Note that inFIG.22AandFIG.22B, the coloring layer132, the plug106, and the like are not illustrated.

FIG.22Aillustrates a region180and a region182in addition to the structure described with reference toFIG.19A, in order to explain the light-emitting region of the display device. The region180functions as the light-emitting region of the display device, and the region182functions as a non-light-emitting region of the display device.

In the light-emitting region of the display device, the EL layer is provided between a pair of electrodes (also referred to as between upper and lower electrodes or between an anode and a cathode). The EL layer includes the common layer114in addition to the island-shaped EL layer113. In the structure illustrated as an example inFIG.22A, the EL layer113includes a hole-injection layer113-1, a hole-transport layer113-2, a light-emitting layer113-3, and an electron-transport layer113-4. InFIG.22A, the common layer114functions as the electron-injection layer.

FIG.22Bis a cross-sectional view illustrating one embodiment of the display device. The display device illustrated inFIG.22Bincludes the insulating layer105, the conductive layer111R over the insulating layer105, the conductive layer111G over the insulating layer105, the conductive layer112R over the conductive layer111R, the conductive layer112G over the conductive layer111G, an insulating layer127bin contact with the insulating layer105, the conductive layer111R, the conductive layer111G, the conductive layer112R, and the conductive layer112G, the EL layer113in contact with the insulating layer127b, the conductive layer112R, and the conductive layer112G, the common layer114over the EL layer113, the common electrode115over the common layer114, and the protective layer131over the common electrode115.

In the light-emitting region of the display device illustrated inFIG.22B, the EL layer113and the common layer114are provided as the EL layer between the pair of electrodes. Unlike inFIG.22A, the EL layer113illustrated inFIG.22Bis a continuous film shared by a plurality of light-emitting elements. In the structure illustrated as an example inFIG.22B, the EL layer113includes the hole-injection layer113-1, the hole-transport layer113-2, the light-emitting layer113-3, and the electron-transport layer113-4. InFIG.22B, the common layer114functions as the electron-injection layer.

InFIG.22B, the insulating layer127bis provided to cover the side surface of the conductive layer111R, the side surface of the conductive layer111G, the side surface and part of the upper surface of the conductive layer112R, and the side surface and part of the upper surface of the conductive layer112G. In this manner, the insulating layer127bfunctions as a structure body (also referred to as a bank) that covers the side surface of the conductive layer and part of the upper surface of the conductive layer. That is, the insulating layer127bis provided to include a region in contact with the conductive layer111R, the conductive layer111G, the conductive layer112R, and the conductive layer112G.

FIG.22Billustrates a region184and a region186. The region184functions as the light-emitting region of the display device, and the region186functions as the non-light-emitting region of the display device.

As illustrated inFIG.22A, in the display device of one embodiment of the present invention, the island-shaped EL layer113(here, the hole-injection layer113-1, the hole-transport layer113-2, the light-emitting layer113-3, and the electron-transport layer113-4) is provided for each light-emitting element, whereby generation of lateral leakage current between the subpixels can be inhibited. In particular, the island-shaped hole-injection layer113-1in the EL layer113can suitably reduce lateral leakage current between the subpixels. Since the hole-injection layer113-1has higher conductivity than the other layers in the EL layer113, at least the hole-injection layer113-1is preferably divided between adjacent subpixels as illustrated inFIG.22A.

In the region180functioning as the light-emitting region inFIG.22A, the difference between the distance (denoted as D1) between the pair of electrodes in the center portion of the EL layer (the EL layer113and the common layer114) and the distance (denoted as D2) between the pair of electrodes in the end portion of the EL layer (the EL layer113and the common layer114) is preferably small. Specifically, the distance (D2) between the pair of electrodes in the end portion of the EL layer is preferably less than ±10%, further preferably less than ±3%, of the distance (D1) between the pair of electrodes in the center portion of the EL layer. Light emission from the light-emitting region can be uniform when the difference between the distance (D1) between the pair of electrodes in the center portion of the EL layer and the distance (D2) between the pair of electrodes in the end portion of the EL layer is made small or eliminated.

Meanwhile, in the case where the EL layer113is shared by adjacent subpixels, particularly the hole-injection layer113-1is shared by adjacent subpixels, as illustrated inFIG.22B, the region186functioning as a non-light-emitting region might partly or wholly emit light. In other words, lateral leakage current might be generated between the adjacent subpixels. Moreover, in the region184functioning as a light-emitting region inFIG.22B, the difference between the distance (denoted as D3) between the pair of electrodes in the center portion of the EL layer (the EL layer113and the common layer114) and the distance (denoted as D4) between the pair of electrodes in the end portion of the EL layer (the EL layer113and the common layer114) is larger than the difference between D1and D2described above.

InFIG.22B, the distance (denoted as D5) between the pair of electrodes in the region186functioning as a non-light-emitting region is larger than the distance (D4) between the pair of electrodes in the end portion of the EL layer. Note that the distance (D5) between the pair of electrodes in the region186is the value of the sum of the thickness of the EL layer113, the thickness of the common layer114, and the thickness of the end portion of the insulating layer127b. For example, in the case where the region186functioning as a non-light-emitting region partly emits light, light resonates in the distance (D5) between the pair of electrodes in the region186, and therefore the distance is different from the distance in which light resonates in the region184functioning as a light-emitting region. Thus, in the case where the region186emits light, the distance in which light resonates is varied from that in the region184, and accordingly the region186and the region184differ in one or more of luminance, chromaticity, and the direction of light emission. In the case where light emission from the region184functioning as a light-emitting region and the region186functioning as a non-light-emitting region is mixed, the emission spectrum might be broad or have a shape with a plurality of peaks. By contrast, in the structure illustrated inFIG.22A, the emission spectrum can be inhibited from being broad or from having a shape with a plurality of peaks because of the structure in which light emission from the non-light-emitting region is reduced.

The display device preferably has a structure in which the chromaticity is constant either at high luminance (e.g., 10000 cd/m2) or low luminance (e.g., 100 cd/m2). To achieve this, the structure illustrated inFIG.22Ais more suitable than the structure illustrated inFIG.22B.

FIG.23illustrates a modification example of the structure illustrated inFIG.21A. Note thatFIG.23is a cross-sectional view in which, for example, the microcavity structure described above is omitted and the vicinity of the subpixel110R and the subpixel110G illustrated in FIG.21A is enlarged. That is,FIG.23illustrates an example in which the structure illustrated inFIG.21Aand the structure illustrated inFIG.22Aare combined.

Manufacturing Method Example 1

A manufacturing method example of the display device100having the structure illustrated inFIG.2Aand the structure illustrated inFIG.18Awill be described below with reference to drawings.

Thin films included in the display device (insulating films, semiconductor films, conductive films, and the like) can be formed by a sputtering method, a chemical vapor deposition (CVD) method, a vacuum evaporation method, a pulsed laser deposition (PLD) method, an ALD method, or the like. Examples of the CVD method include a plasma-enhanced chemical vapor deposition (PECVD) method and a thermal CVD method. As an example of the thermal CVD method, a metal organic chemical vapor deposition (MOCVD) method can be given.

The thin films included in the display device (insulating films, semiconductor films, conductive films, and the like) can be formed by a wet film formation method such as spin coating, dipping, spray coating, inkjetting, dispensing, screen printing, offset printing, a doctor knife method, slit coating, roll coating, curtain coating, or knife coating.

For fabrication of the light-emitting elements, a vacuum process such as an evaporation method or a solution process such as a spin coating method or an inkjet method can be especially used. Examples of an evaporation method include physical vapor deposition methods (PVD methods) such as a sputtering method, an ion plating method, an ion beam evaporation method, a molecular beam evaporation method, and a vacuum evaporation method, and a chemical vapor deposition method (CVD method). In particular, the EL layer can be formed by an evaporation method (e.g., a vacuum evaporation method), a coating method (a dip coating method, a die coating method, a bar coating method, a spin coating method, a spray coating method, or the like), a printing method (an inkjet method, a screen printing (stencil) method, an offset printing (planography) method, a flexography (relief printing) method, a gravure printing method, a micro-contact printing method, or the like), or the like.

Thin films that form the display device can be processed by, for example, a photolithography method. Alternatively, the thin films may be processed by a nanoimprinting method, a sandblasting method, a lift-off method, or the like. An island-shaped thin film may be directly formed by a film formation method using a shielding mask such as a metal mask.

There are the following two typical methods of a photolithography method. In one of the methods, a resist mask is formed over a thin film that is to be processed, the thin film is processed by, for example, etching, and then the resist mask is removed. In the other method, after a photosensitive thin film is formed, light exposure and development are performed, so that the thin film is processed into a desired shape.

For light exposure in a photolithography method, for example, an i-line (with a wavelength of 365 nm), a g-line (with a wavelength of 436 nm), an h-line (with a wavelength of 405 nm), or light in which these lines are mixed can be used. Besides, ultraviolet light, KrF laser light, ArF laser light, or the like can be used. In addition, light exposure may be performed by liquid immersion exposure technique. The light exposure may be performed with the use of extreme ultraviolet (EUV) light or X-rays. Instead of the light used for the light exposure, an electron beam can also be used. It is preferable to use extreme ultraviolet light, X-rays, or an electron beam because extremely minute processing is possible. Note that when light exposure is performed by scanning of a beam such as an electron beam, a photomask is not needed.

For etching of the thin films, a dry etching method, a wet etching method, a sandblasting method, or the like can be used.

To manufacture the display device100having the structure illustrated inFIG.2Aand the structure illustrated inFIG.18A, first, the insulating layer101is formed over a substrate (not illustrated), as illustrated inFIG.24A. Next, the conductive layer102and the conductive layer109are formed over the insulating layer101, and the insulating layer103is formed over the insulating layer101so as to cover the conductive layer102and the conductive layer109. Then, the insulating layer104is formed over the insulating layer103, and the insulating layer105is formed over the insulating layer104.

As the substrate, a substrate having at least heat resistance high enough to withstand heat treatment performed later can be used. In the case where an insulating substrate is used as the substrate, a glass substrate, a quartz substrate, a sapphire substrate, a ceramic substrate, an organic resin substrate, or the like can be used. Alternatively, it is possible to use a semiconductor substrate such as a single crystal semiconductor substrate or a polycrystalline semiconductor substrate of silicon, silicon carbide, or the like, a compound semiconductor substrate of silicon germanium or the like, or an SOI substrate.

Note thatFIG.24Aillustrates a cross-sectional view along the line A1-A2 and a cross-sectional view along the line B1-B2 side by side. The same applies to the diagrams illustrating the manufacturing method example of the display device in the following description.

Next, openings reaching the conductive layer102are formed in the insulating layer105, the insulating layer104, and the insulating layer103, as illustrated inFIG.24A. Then, the plugs106are formed to fill the openings.

Next, a conductive film111fto be the conductive layer111R, the conductive layer111G, the conductive layer111B, and the conductive layer111C later is formed over the plugs106and over the insulating layer105, as illustrated inFIG.24A. For formation of the conductive film111f, a sputtering method or a vacuum evaporation method can be used, for example. A metal material can be used for the conductive film111f, for example.

The conductive film111fcan have a three-layer structure in which a film to be the conductive layer111alater, a film to be the conductive layer111blater, and a film to be the conductive layer111clater are stacked in this order from the bottom. Alternatively, the conductive film111fcan have a two-layer structure in which the film to be the conductive layer111alater and the film to be the conductive layer111blater are stacked in this order from the bottom. For example, titanium can be used for the film to be the conductive layer111a, aluminum can be used for the film to be the conductive layer111b, and titanium can be used for the film to be the conductive layer111c. Alternatively, the conductive film111fcan have a single-layer structure.

Then, as illustrated inFIG.24B, the conductive film111fis processed by a photolithography method, for example, so that the conductive layer111R, the conductive layer111G, the conductive layer111B, and the conductive layer111C are formed. Specifically, the conductive film111fis partly removed by an etching method after a resist mask is formed, for example. In the case where a metal material is used for the conductive film111f, the conductive film111fcan be removed by a dry etching method, for example. Here, in the case where part of the conductive film111fis removed by a dry etching method, for example, a depressed portion may be formed in a region of the insulating layer105that does not overlap with the conductive layer111.

As illustrated in FIG.2B1, FIG.2B2, andFIG.4C, the conductive layer111R, the conductive layer111G, the conductive layer111B, and the conductive layer111C can each have a three-layer structure in which the conductive layer111a, the conductive layer111bover the conductive layer111a, and the conductive layer111cover the conductive layer111bare stacked. As illustrated inFIG.3A,FIG.3B, andFIG.4B, the conductive layer111R, the conductive layer111G, the conductive layer111B, and the conductive layer111C can each have a two-layer structure in which the conductive layer111aand the conductive layer111bover the conductive layer111aare stacked. As illustrated inFIG.4A, the conductive layer111R, the conductive layer111G, the conductive layer111B, and the conductive layer111C can each have a single-layer structure.

Next, as illustrated inFIG.24C, a conductive film112fto be the conductive layer112R, the conductive layer112G, the conductive layer112B, and the conductive layer112C later is formed over the conductive layer111R, over the conductive layer111G, over the conductive layer111B, over the conductive layer111C, and over the insulating layer105. The conductive film112fcan be formed by a sputtering method or a vacuum evaporation method, for example.

In the case where the conductive layer112having the structure illustrated in FIG.2B1andFIG.3Ais formed, a conductive oxide, for example, can be used for the conductive film112f. In the case where the conductive layer112having the structure illustrated in FIG.2B2andFIG.3Bis formed, the conductive film112fcan have a two-layer structure in which a film to be the conductive layer112alater and a film to be the conductive layer112blater are stacked in this order from the bottom. A metal material such as titanium, silver, or an alloy containing silver can be used for the film to be the conductive layer112aand a conductive oxide can be used for the film to be the conductive layer112b, for example. In the case where the conductive layer112having the structure illustrated inFIG.4A,FIG.4B, andFIG.4Cis formed, the conductive film112fcan have a three-layer structure in which the film to be the conductive layer112alater, the film to be the conductive layer112blater, and a film to be the conductive layer112clater are stacked in this order from the bottom. A conductive oxide can be used for the film to be the conductive layer112a, silver or an alloy containing silver can be used for the film to be the conductive layer112b, and a conductive oxide can be used for the film to be the conductive layer112c, for example.

The conductive film112fcan be formed by an ALD method. For the conductive film112f, an oxide containing one or more selected from indium, tin, zinc, gallium, titanium, aluminum, and silicon can be used. In this case, the conductive film112fcan be formed by repeating a cycle of introduction of a precursor (generally referred to as a metal precursor or the like in some cases), purge of the precursor, introduction of an oxidizer (generally referred to as a reactant, a non-metal precursor, or the like in some cases), and purge of the oxidizer. Here, in the case where an oxide film containing a plurality of kinds of metals, such as an indium tin oxide film, is formed as the conductive film112f, the composition of the metals can be controlled by varying the number of cycles for different kinds of precursors.

For example, in the case where an indium tin oxide film is formed as the conductive film112f, after a precursor containing indium is introduced, the precursor is purged, and an oxidizer is introduced to form an In—O film, and then a precursor containing tin is introduced, the precursor is purged, and an oxidizer is introduced to form a Sn—O film. Here, when the number of cycles of forming an In—O film is larger than the number of cycles of forming a Sn—O film, the number of In atoms contained in the conductive film112fcan be larger than the number of Sn atoms contained therein.

For example, to form a zinc oxide film as the conductive film112f, a Zn—O film is formed in the above procedure. For example, to form an aluminum zinc oxide film as the conductive film112f, a Zn—O film and an Al—O film are formed in the above procedure. For example, to form a titanium oxide film as the conductive film112f, a Ti—O film is formed in the above procedure. For example, to form an indium tin oxide film containing silicon as the conductive film112f, an In—O film, a Sn—O film, and a Si—O film are formed in the above procedure. For example, to form a zinc oxide film containing gallium as the conductive film112f, a Ga—O film and a Zn—O film are formed in the above procedure.

As a precursor containing indium, it is possible to use, for example, triethylindium, trimethylindium, or [1,1,1-trimethyl-N-(trimethylsilyl)amide]-indium. As a precursor containing tin, it is possible to use, for example, tin chloride or tetrakis(dimethylamido) tin. As a precursor containing zinc, it is possible to use, for example, diethylzinc or dimethylzinc. As a precursor containing gallium, it is possible to use, for example, triethylgallium. As a precursor containing titanium, it is possible to use, for example, titanium chloride, tetrakis(dimethylamido) titanium, or tetraisopropyl titanate. As a precursor containing aluminum, it is possible to use, for example, aluminum chloride or trimethylaluminum. As a precursor containing silicon, it is possible to use, for example, trisilylamine, bis(diethylamino) silane, tris(dimethylamino) silane, bis(tert-butylamino) silane, or bis(ethylmethylamino) silane. As the oxidizer, water vapor, oxygen plasma, or an ozone gas can be used.

Here, a surface of the conductive layer111might be oxidized after the formation of the conductive layer111but before the formation of the conductive film112f, for example. For example, exposure to the air after the formation of the conductive layer111might allow oxygen contained in the air to oxidize a surface of the conductive layer111. Here, in the case where a metal whose electrical resistance would be increased by oxidation is used for the uppermost layer of the conductive layer111, the electric resistance at the contact interface between the conductive layer111and the conductive layer112might be increased as compared with the case where the surface of the conductive layer111is not oxidized. Consequently, defects might be generated in the manufactured display device to reduce the reliability of the display device.

Thus, an oxide on a surface of the conductive layer111is preferably remover after the formation of the conductive layer111but before the formation of the conductive film112f. It is preferable that the formation of the conductive film112ffollow the removal of the oxide without exposure to the air. In this case, the electrical resistance at the contact interface between the conductive layer111and the conductive layer112can be made low. Accordingly, generation of a defect in the display device100can be inhibited, which makes the display device100highly reliable. The oxide on a surface of the conductive layer111can be removed by a reverse sputtering method, for example.

A reverse sputtering method refers to a method in which property modification of a surface to be processed is caused by collision of ions with the surface to be processed, in contrast to collision of ions with a sputtering target in normal sputtering. An example of a method of making ions collide with a surface to be processed is a method in which high-frequency voltage is applied to the side of the surface to be processed in a gas atmosphere containing a Group 18 element such as argon so that plasma is generated near the surface to be processed. Note that an atmosphere containing nitrogen, oxygen, or the like may be used instead of the gas atmosphere containing a Group 18 element. An apparatus used for the reverse sputtering method is not limited to a sputtering apparatus, and the same treatment can also be performed with a plasma CVD apparatus, a dry etching apparatus, or the like.

Then, as illustrated inFIG.24D, the conductive film112fis processed by a photolithography method, for example, so that the conductive layer112R, the conductive layer112G, the conductive layer112B, and the conductive layer112C are formed. Specifically, the conductive film112fis partly removed by an etching method after a resist mask is formed, for example. In the case where a conductive oxide is used for the conductive film112f, the conductive film112fcan be removed by a wet etching method, for example. The conductive layer112is formed to cover the upper surface and the side surface of the conductive layer111. In the case where the conductive layer112has the structure illustrated in FIG.2B2, a metal material is used for the conductive layer112a, and a conductive oxide is used for the conductive layer112b, for example, a conductive film to be the conductive layer112acan be partly removed by a dry etching method after a conductive film to be the conductive layer112bis partly removed by a wet etching method. Note that the conductive film to be the conductive layer112amay be partly removed by a wet etching method and the conductive film to be the conductive layer112bmay be partly removed by a dry etching method.

Here, in the case where the conductive layer112is a stacked-layer structure of the conductive layer112aand the conductive layer112bas illustrated in FIG.2B2andFIG.3B, a film to be the conductive layer112a, which is included in the conductive film112f, can be formed using a metal material such as titanium, silver, or an alloy containing silver. A film to be the conductive layer112b, which is included in the conductive film112f, can be formed using a conductive oxide such as indium tin oxide, for example. As described above, using silver or an alloy containing silver for the conductive layer112aenables the pixel electrode to have high visible light reflectance as described above. Meanwhile, using titanium for the film to be the conductive layer112afacilitates processing of the film to form the conductive layer112abecause titanium has better processability in etching than silver, as described above.

Then, the conductive layer112is preferably subjected to hydrophobic treatment. The hydrophobic treatment can change the property of the surface of a processing target from hydrophilic to hydrophobic, or can improve the hydrophobic property of the surface of the processing target. The hydrophobic treatment for the conductive layer112can increase the adhesion between the conductive layer112and the EL layer113formed in a later step and inhibits peeling. Note that the hydrophobization treatment is not necessarily performed.

The hydrophobic treatment can be performed by fluorine modification of the conductive layer112, for example. The fluorine modification can be performed by, for example, treatment or heat treatment using a fluorine-containing gas, plasma treatment in an atmosphere of a fluorine-containing gas, or the like. As the fluorine-containing gas, a fluorine gas such as a fluorocarbon gas can be used, for example. As a fluorocarbon gas, a low carbon fluoride gas such as a carbon tetrafluoride (CF4) gas, a C4F6gas, a C2F6gas, a C4F8gas, or a CsF& gas can be used, for example. Moreover, as the fluorine-containing gas, a SF6gas, a NF3gas, a CHF: gas, or the like can be used, for example. A helium gas, an argon gas, a hydrogen gas, a hydrogen gas, an oxygen gas, or the like can be added to these gases as appropriate.

In addition, treatment using a silylation agent is performed on the surface of the conductive layer112after plasma treatment is performed in a gas atmosphere containing a Group 18 element such as argon, so that the surface of the conductive layer112can become hydrophobic. As the silylation agent, hexamethyldisilazane (HMDS), N-trimethylsilylimidazole (TMSI), or the like can be used. Alternatively, treatment using a silane coupling agent is performed on the surface of the conductive layer112after plasma treatment is performed in a gas atmosphere containing a Group 18 element such as argon, so that the surface of the conductive layer112can become hydrophobic.

Plasma treatment in a gas atmosphere containing a Group 18 element such as argon is performed on the surface of the conductive layer112, whereby the surface of the conductive layer112can be damaged. Accordingly, a methyl group included in the silylation agent such as HMDS is likely to bond to the surface of the conductive layer112. Moreover, silane coupling due to the silane coupling agent is likely to occur. As described above, treatment using a silylation agent or a silane coupling agent performed on the surface of the conductive layer112after plasma treatment in a gas atmosphere containing a Group 18 element such as argon enables the surface of the conductive layer112to become hydrophobic.

The treatment using the silylation agent, the silane coupling agent, or the like can be performed by application of the silylation agent, the silane coupling agent, or the like by a spin coating method or a dipping method, for example. The treatment using the silylation agent, the silane coupling agent, or the like can also be performed by forming a film containing the silylation agent, a film containing the silane coupling agent, or the like over the conductive layer112and the like by a gas phase method, for example. In a gas phase method, first, a material containing the silylation agent, a material containing the silane coupling agent, or the like is volatilized so that the silylation agent, the silane coupling agent, or the like is included in the atmosphere. Then, the substrate where the conductive layer112, for example, is formed is put in the atmosphere. Thus, a film containing the silylation agent, the silane coupling agent, or the like can be formed over the conductive layer112, and the surface of the conductive layer112can be made hydrophobic.

Next, as illustrated inFIG.25A, an EL film113Rf to be the EL layer113R later is formed over the conductive layer112R, over the conductive layer112G, over the conductive layer112B, and over the insulating layer105.

As illustrated inFIG.25A, the EL film113Rf is not formed over the conductive layer112C. The EL film113Rf can be formed only in an intended region by using an area mask, for example. Employing a film formation step using an area mask and a processing step using a resist mask enables a light-emitting element to be manufactured by a relatively easy process.

The EL film113Rf can be formed by an evaporation method, specifically a vacuum evaporation method, for example. The EL film113Rf may be formed by a transfer method, a printing method, an inkjet method, a coating method, or the like.

Next, as illustrated inFIG.25A, the mask film118Rf to be the mask layer118R later and the mask film119Rf to be the mask layer119R later are sequentially formed over the EL film113Rf, over the conductive layer112C, and over the insulating layer105.

Although this embodiment describes an example in which the mask film is formed with a two-layer structure of the mask film118Rf and the mask film119Rf, the mask film may have a single-layer structure or a stacked-layer structure of three or more layers.

The mask layer provided over the EL film113Rf can reduce damage to the EL film113Rf in the manufacturing process of the display device, increasing the reliability of the light-emitting element.

As the mask film118Rf, a film that is highly resistant to the processing conditions for the EL film113Rf, specifically, a film having high etching selectivity with the EL film113Rf is used. As the mask film119Rf, a film having high etching selectivity with the mask film118Rf is used.

The mask film118Rf and the mask film119Rf are formed at a temperature lower than the upper temperature limit of the EL film113Rf. The typical substrate temperatures in formation of the mask film118Rf and the mask film119Rf are each lower than or equal to 200° C., preferably lower than or equal to 150° C., further preferably lower than or equal to 120° C., still further preferably lower than or equal to 100° C., yet still further preferably lower than or equal to 80° C.

As the mask film118Rf and the mask film119Rf, it is preferable to use a film that can be removed by a wet etching method. Using a wet etching method can reduce damage to the EL film113Rf in processing the mask film118Rf and the mask film119Rf, as compared to the case of using a dry etching method.

The mask film118Rf and the mask film119Rf can be formed by a sputtering method, an ALD method (a thermal ALD method or a PEALD method), a CVD method, or a vacuum evaporation method, for example. Alternatively, the aforementioned wet film formation method may be used for the formation.

Note that the mask film118Rf, which is formed over and in contact with the EL film113Rf, is preferably formed by a formation method that causes less damage to the EL film113Rf than a formation method for the mask film119Rf. For example, the mask film118Rf is preferably formed by an ALD method or a vacuum evaporation method rather than a sputtering method.

As the mask film118Rf and the mask film119Rf, it is possible to use one or more of a metal film, an alloy film, a metal oxide film, a semiconductor film, an organic insulating film, and an inorganic insulating film, for example.

For the mask film118Rf and the mask film119Rf, it is possible to use a metal material such as gold, silver, platinum, magnesium, nickel, tungsten, chromium, molybdenum, iron, cobalt, copper, palladium, titanium, aluminum, yttrium, zirconium, or tantalum or an alloy material containing any of the metal materials, for example. It is particularly preferable to use a low-melting-point material such as aluminum or silver. The use of a metal material capable of blocking ultraviolet rays for one or both of the mask film118Rf and the mask film119Rf is preferable, in which case the EL film113Rf can be inhibited from being irradiated with ultraviolet light and deteriorating.

For each of the mask film118Rf and the mask film119Rf, it is possible to use a metal oxide such as In—Ga—Zn oxide, indium oxide, In—Zn oxide, In—Sn oxide, indium titanium oxide (In—Ti oxide), indium tin zinc oxide (In—Sn—Zn oxide), indium titanium zinc oxide (In—Ti—Zn oxide), indium gallium tin zinc oxide (In—Ga—Sn—Zn oxide), or indium tin oxide containing silicon.

As the mask film, a film containing a material having a light-blocking property, particularly with respect to ultraviolet rays, can be used. For example, a film having a property of reflecting ultraviolet rays or a film absorbing ultraviolet rays can be used. Although a variety of materials such as a metal, an insulator, a semiconductor, and a metalloid that have a property of blocking ultraviolet rays can be used as the material having a light-blocking property, the mask film is preferably a film capable of being processed by etching and is particularly preferably a film having good processability because part or the whole of the mask film is removed in a later step.

Examples of a material with an affinity for a semiconductor manufacturing process include semiconductor materials such as silicon and germanium. Other examples include oxides and nitrides of the above semiconductor materials. Other examples include non-metallic (metalloid) materials such as carbon and compounds thereof. Other examples include metals such as titanium, tantalum, tungsten, chromium, aluminum, and alloys containing one or more of these metals. Other examples include oxides containing the above metal such as titanium oxide and chromium oxide, and nitrides such as titanium nitride, chromium nitride, and tantalum nitride.

The use of a film containing a material having a light-blocking property with respect to ultraviolet rays can inhibit the EL layer from being irradiated with ultraviolet rays in a light exposure step, for example. The EL layer is inhibited from being damaged by ultraviolet rays, so that the reliability of the light-emitting element can be improved.

Note that the film containing a material having a light-blocking property with respect to ultraviolet ray's can have the same effect even when used as an insulating film125fto be described later.

As the mask film118Rf and the mask film119Rf, a variety of inorganic insulating films that can be used as the protective layer131can be used. In particular, an oxide insulating film is preferable because its adhesion to the EL film113Rf is higher than that of a nitride insulating film. For example, an inorganic insulating material such as aluminum oxide, hafnium oxide, or silicon oxide can be used for the mask film118Rf and the mask film119Rf. As the mask film118Rf or the mask film119Rf, an aluminum oxide film can be formed by an ALD method, for example. The use of an ALD method is preferable, in which case damage to a base (in particular, the EL layer) can be reduced.

For example, an inorganic insulating film (e.g., an aluminum oxide film) formed by an ALD method can be used as the mask film118Rf, and an inorganic film (e.g., an In—Ga—Zn oxide film, an aluminum film, or a tungsten film) formed by a sputtering method can be used as the mask film119Rf.

Note that the same inorganic insulating film can be used for both the mask film118Rf and the insulating layer125that is to be formed later. For example, an aluminum oxide film formed by an ALD method can be used for both the mask film118Rf and the insulating layer125. Here, for the mask film118Rf and the insulating layer125, the same film formation condition may be used or different film formation conditions may be used. For example, when the mask film118Rf is formed under conditions similar to those of the insulating layer125, the mask film118Rf can be an insulating film having a high barrier property against at least one of water and oxygen. Meanwhile, the mask film118Rf is a layer most or all of which is to be removed in a later step, and thus is preferably easy to process. Therefore, the mask film118Rf is preferably formed with a substrate temperature lower than that for formation of the insulating layer125.

An organic material may be used for one or both of the mask film118Rf and the mask film119Rf. For example, as the organic material, a material that can be dissolved in a solvent chemically stable may be used. Specifically, a material that will be dissolved in water or alcohol can be suitably used. In film formation of a film of such a material, it is preferable to apply the material dissolved in a solvent such as water or alcohol by a wet film formation method and then perform heat treatment for evaporating the solvent. At this time, the heat treatment is preferably performed in a reduced-pressure atmosphere, in which case the solvent can be removed at a low temperature in a short time and thermal damage to the EL film113Rf can be reduced accordingly.

For each of the mask film118Rf and the mask film119Rf, an organic resin such as polyvinyl alcohol (PVA), polyvinyl butyral, polyvinylpyrrolidone, polyethylene glycol, polyglycerin, pullulan, water-soluble cellulose, an alcohol-soluble polyamide resin, or a fluororesin such as perfluoropolymer may be used.

For example, an organic film (e.g., a PVA film) formed by an evaporation method or the above wet film formation method can be used as the mask film118Rf, and an inorganic film (e.g., a silicon nitride film) formed by a sputtering method can be used as the mask film119Rf.

Note that in the display device of one embodiment of the present invention, part of the mask film remains as the mask layer in some cases.

Then, a resist mask190R is formed over the mask film119Rf, as illustrated inFIG.25A. The resist mask190R can be formed by application of a photosensitive material (photoresist), exposure, and development.

Either a positive resist material or a negative resist material may be used to form the resist mask190R.

The resist mask190R is provided at a position overlapping with the conductive layer112R. Note that the resist mask190R is preferably provided also at a position overlapping with the conductive layer112C. This can inhibit the conductive layer112C from being damaged during the manufacturing process of the display device. Note that the resist mask190R is not necessarily provided over the conductive layer112C. The resist mask190R is preferably provided to cover the area from the end portion of the EL film113Rf to the end portion of the conductive layer112C (the end portion closer to the EL film113Rf), as illustrated in the cross-sectional view along the line B1-B2 inFIG.25A.

Subsequently, as illustrated inFIG.25AandFIG.25B, part of the mask film119Rf is removed using the resist mask190R, whereby the mask layer119R is formed. The mask layer119R remains over the conductive layer112R and over the conductive layer112C. After that, the resist mask190R is removed. Next, part of the mask film118Rf is removed using the mask layer119R as a mask (also referred to as a hard mask), whereby the mask layer118R is formed.

The mask film118Rf and the mask film119Rf can be processed by a wet etching method or a dry etching method. The mask film118Rf and the mask film119Rf are preferably processed by anisotropic etching.

Using a wet etching method can reduce damage to the EL film113Rf in processing the mask film118Rf and the mask film119Rf, as compared to the case of using a dry etching method. In the case of using a wet etching method, it is preferable to use a developer, a tetramethylammonium hydroxide aqueous solution (TMAH), dilute hydrofluoric acid, oxalic acid, phosphoric acid, acetic acid, nitric acid, or a chemical solution containing a mixed solution of any of these acids, for example.

Since the EL film113Rf is not exposed in processing the mask film119Rf, the range of choices of the processing method is wider than that for processing the mask film118Rf. Specifically, even in the case where a gas containing oxygen is used as the etching gas in the processing of the mask film119Rf, deterioration of the EL film113Rf can be inhibited as compared to the case where a gas containing oxygen is used as the etching gas in the processing of the mask film118Rf.

In the case of using a dry etching method for processing the mask film118Rf, deterioration of the EL film113Rf can be inhibited by not using a gas containing oxygen as the etching gas. In the case of using a dry etching method, it is preferable to use a gas containing CF4, C4F8, SF6, CHF3, Cl2, H2O, BCl3, or a Group 18 element, for example, as the etching gas. He can be used as the Group 18 element, for example.

For example, in the case where an aluminum oxide film formed by an ALD method is used as the mask film118Rf, part of the mask film118Rf can be removed by a dry etching method using a combination of CHF3and He or a combination of CHF3, He, and CH4. In the case where an In—Ga—Zn oxide film formed by a sputtering method is used as the mask film119Rf, part of the mask film119Rf can be removed by a wet etching method using a diluted phosphoric acid.

Alternatively, part of the mask film119Rf may be removed by a dry etching method using CH4and Ar. Alternatively, part of the mask film119Rf can be removed by a wet etching method using diluted phosphoric acid. In the case where a tungsten film formed by a sputtering method is used as the mask film119Rf, part of the mask film119Rf can be removed by a dry etching method using SF6, a combination of CF4and O2, or a combination of CF4, Cl2, and O2.

The resist mask190R can be removed by ashing using oxygen plasma, for example. Alternatively, an oxygen gas and CF4, C4F8, SF6, CHF3, Cl2, H2O, BCl3, or a Group 18 element may be used. He can be used as the Group 18 element, for example. Alternatively, the resist mask190R may be removed by wet etching. At this time, the mask film118Rf is positioned on the outermost surface and the EL film113Rf is not exposed; thus, the EL film113Rf can be inhibited from being damaged in the step of removing the resist mask190R. In addition, the range of choices of the method for removing the resist mask190R can be widened.

Next, as illustrated inFIG.25AandFIG.25B, the EL film113Rf is processed, so that the EL layer113R is formed. For example, part of the EL film113Rf is removed using the mask layer119R and the mask layer118R as a mask to form the EL layer113R.

Accordingly, as illustrated inFIG.25B, a stacked-layer structure of the EL layer113R, the mask layer118R, and the mask layer119R remains over the conductive layer112R. The conductive layer112G and the conductive layer112B are exposed.

FIG.25Billustrates an example in which the end portion of the EL layer113R is positioned on the outer side of the end portion of the conductive layer112R. Such a structure can increase the aperture ratio of the pixel. Although not illustrated inFIG.25B, by the above etching treatment, a depressed portion may be formed in the insulating layer105in a region that does not overlap with the EL layer113R.

The EL layer113R covers the upper surface and the side surface of the conductive layer112R and thus, the subsequent steps can be performed without exposure of the conductive layer112R. When the end portion of the conductive layer112R is exposed, corrosion might occur in the etching step, for example. A product generated by corrosion of the conductive layer112R may be unstable, and for example, might be dissolved in a solution when wet etching is performed and might be scattered in an atmosphere when dry etching is performed. The product dissolved in a solution or scattered in an atmosphere might be attached to a surface to be processed, the side surface of the EL layer113R, and the like, which adversely affects the characteristics of the light-emitting element or forms a leakage path between the light-emitting elements in some cases. In a region where the end portion of the conductive layer112R is exposed, adhesion between layers in contact with each other might be lowered, which might be likely to cause peeling of the EL layer113R or the conductive layer112R.

Thus, the structure where the EL layer113R covers the upper surface and the side surface of the conductive layer112R can improve the yield and characteristics of the light-emitting element, for example.

As described above, the resist mask190R is preferably provided to cover the area from the end portion of the EL layer113R to the end portion of the conductive layer112C (the end portion closer to the EL layer113R) in the cross section B1-B2. Thus, as illustrated inFIG.25B, the mask layer118R and mask layer119R are provided to cover the area from the end portion of the EL layer113R to the end portion of the conductive layer112C (the end portion closer to the EL layer113R) in the cross section B1-B2. Hence, the insulating layer105can be inhibited from being exposed in the cross section B1-B2, for example. This can inhibit the insulating layer105, the insulating layer104, and the insulating layer103from being partly removed by etching, for example, and thus inhibit the conductive layer109from being exposed. Thus, unintentional electrical connection between the conductive layer109and another conductive layer can be inhibited. For example, a short circuit between the conductive layer109and the common electrode115formed in a later step can be inhibited.

The EL film113Rf is preferably processed by anisotropic etching. In particular, anisotropic dry etching is preferable. Alternatively, wet etching may be used.

In the case of using a dry etching method, deterioration of the EL film113Rf can be inhibited by not using a gas containing oxygen as the etching gas.

A gas containing oxygen may be used as the etching gas. When the etching gas contains oxygen, the etching rate can be increased. Therefore the etching can be performed under a low-power condition while an adequately high etching rate is maintained. Thus, damage to the EL film113Rf can be inhibited. Furthermore, a defect such as attachment of a reaction product generated at the etching can be inhibited.

In the case of using a dry etching method, it is preferable to use a gas containing at least one of H2, CF4, C4F8, SF6, CHF3, Cl2, H2O, BCl3, and a Group 18 element such as He or Ar as the etching gas, for example. Alternatively, a gas containing oxygen and at least one kind of the above is preferably used as the etching gas. Alternatively, an oxygen gas may be used as the etching gas. Specifically, for example, a gas containing H2and Ar or a gas containing CF4and He can be used as the etching gas. For example, a gas containing CF4, He, and oxygen can be used as the etching gas. For example, a gas containing H2and Ar and a gas containing oxygen can be used as the etching gas.

As described above, in one embodiment of the present invention, the mask layer119R is formed in the following manner: the resist mask190R is formed over the mask film119Rf, and part of the mask film119Rf is removed using the resist mask190R. After that, part of the EL film113Rf is removed using the mask layer119R as a mask, so that the EL layer113R is formed. In other words, the EL layer113R can be formed by processing the EL film113Rf by a photolithography method. Note that part of the EL film113Rf may be removed using the resist mask190R. Then, the resist mask190R may be removed.

Next, hydrophobic treatment for the conductive layer112G, for example, is preferably performed. At the time of processing the EL film113Rf, the surface of the conductive layer112G changes to have hydrophilic properties in some cases, for example. The hydrophobization treatment for the conductive layer112G, for example, can increase the adhesion between the conductive layer112G and a layer to be formed in a later step (which is the EL layer113G here) and inhibit peeling. Note that the hydrophobization treatment is not necessarily performed.

Next, as illustrated inFIG.25C, an EL film113Gf to be the EL layer113G later is formed over the conductive layer112G, over the conductive layer112B, over the mask layer119R, and over the insulating layer105.

The EL film113Gf can be formed by a method similar to a method that can be employed to form the EL film113Rf.

Then, as illustrated inFIG.25C, a mask film118Gf to be the mask layer118G later and a mask film119Gf to be a mask layer119G later are sequentially formed over the EL film113Gf and over the mask layer119R. After that, a resist mask190G is formed. The materials and the formation methods of the mask film118Gf and the mask film119Gf are similar to conditions applicable to the mask film118Rf and the mask film119Rf. The materials and the formation method of the resist mask190G are similar to conditions applicable to the resist mask190R.

The resist mask190G is provided at a position overlapping with the conductive layer112G.

Subsequently, as illustrated inFIG.25CandFIG.25D, part of the mask film119Gf is removed using the resist mask190G, whereby the mask layer119G is formed. The mask layer119G remains over the conductive layer112G. After that, the resist mask190G is removed. Then, part of the mask film118Gf is removed using the mask layer119G as a mask, whereby the mask layer118G is formed. Next, the EL film113Gf is processed to form the EL layer113G. For example, part of the EL film113Gf is removed using the mask layer119G and the mask layer118G as a mask to form the EL layer113G.

Accordingly, as illustrated inFIG.25D, the stacked-layer structure of the EL layer113G, the mask layer118G, and the mask layer119G remains over the conductive layer112G. The mask layer119R and the conductive layer112B are exposed.

Next, hydrophobic treatment for the conductive layer112B, for example, is preferably performed. At the time of processing the EL film113Gf, the surface of the conductive layer112B changes to have hydrophilic properties in some cases, for example. The hydrophobization treatment for the conductive layer112B, for example, can increase the adhesion between the conductive layer112B and a layer to be formed in a later step (which is the EL layer113B here) and inhibit peeling. Note that the hydrophobization treatment is not necessarily performed.

Next, as illustrated inFIG.26A, an EL film113Bf to be the EL layer113B later is formed over the conductive layer112B, over the mask layer119R, over the mask layer119G, and over the insulating layer105.

The EL film113Bf can be formed by a method similar to a method that can be employed to form the EL film113Rf.

Then, as illustrated inFIG.26A, a mask film118Bf to be the mask layer118B later and a mask film119Bf to be a mask layer119B later are sequentially formed over the EL film113Bf and over the mask layer119R. After that, a resist mask190B is formed. The materials and the formation methods of the mask film118Bf and the mask film119Bf are similar to conditions applicable to the mask film118Rf and the mask film119Rf. The materials and the formation method of the resist mask190B are similar to conditions applicable to the resist mask190R.

The resist mask190B is provided at a position overlapping with the conductive layer112B.

Subsequently, as illustrated inFIG.26AandFIG.26B, part of the mask film119Bf is removed using the resist mask190B, whereby the mask layer119B is formed. The mask layer119B remains over the conductive layer112B. After that, the resist mask190B is removed. Then, part of the mask film118Bf is removed using the mask layer119B as a mask, whereby the mask layer118B is formed. Next, the EL film113Bf is processed to form the EL layer113B. For example, part of the EL film113Bf is removed using the mask layer119B and the mask layer118B as a mask to form the EL layer113B.

Accordingly, as illustrated inFIG.26B, the stacked-layer structure of the EL layer113B, the mask layer118B, and the mask layer119B remains over the conductive layer112B. The mask layer119R and the mask layer119G are exposed.

Note that the side surface of the EL layer113R, the side surface of the EL layer113G, and the side surface of the EL layer113B are preferably perpendicular or substantially perpendicular to their formation surfaces. For example, the angle between the formation surfaces and these side surfaces is preferably greater than or equal to 60° and less than or equal to 90°.

As described above, the distance between adjacent two layers among the EL layer113R, the EL layer113G, and the EL layer113B formed by a photolithography method can be shortened to less than or equal to 8 μm, less than or equal to 5 μm, less than or equal to 3 μm, less than or equal to 2 μm, or less than or equal to 1 μm. Here, the distance can be specified, for example, by a distance between opposite end portions of two adjacent layers among the EL layer113R, the EL layer113G, and the EL layer113B. The distance between the island-shaped EL layers113is shortened in this manner, whereby a display device with high resolution and a high aperture ratio can be provided.

Next, the mask layer119R, the mask layer119G, and the mask layer119B are preferably removed as illustrated inFIG.26C. The mask layer118R, the mask layer118G, the mask layer118B, the mask layer119R, the mask layer119G, and the mask layer119B might remain in the display device in some cases depending on the subsequent steps. Removing the mask layer119R, the mask layer119G, and the mask layer119B at this stage can inhibit the mask layer119R, the mask layer119G, and the mask layer119B from remaining in the display device. In the case where a conductive material is used for the mask layer119R, the mask layer119G, and the mask layer119B, removing the mask layer119R, the mask layer119G, and the mask layer119B in advance can inhibit generation of leakage current, formation of a capacitor, and the like due to the mask layer119R, the mask layer119G, and the mask layer119B, for example.

Although this embodiment shows an example where the mask layer119R, the mask layer119G, and the mask layer119B are removed, the mask layer119R, the mask layer119G, and the mask layer119B are not necessarily removed. For example, in the case where the mask layer119R, the mask layer119G, and the mask layer119B contain the material having a property of blocking ultraviolet rays, the procedure preferably proceeds to the next step without removing the mask layer119R, the mask layer119G, and the mask layer119B, in which case the EL layer113can be protected from ultraviolet rays.

The step of removing the mask layers can be performed by a method similar to that for the step of processing the mask layers. In particular, using a wet etching method can reduce damage to the EL layer113R, the EL layer113G, and the EL layer113B in removing the mask layers, as compared to the case of using a dry etching method.

The mask layers may be removed by being dissolved in a solvent such as water or alcohol. Examples of alcohol include ethyl alcohol, methyl alcohol, isopropyl alcohol (IPA), and glycerin.

After the mask layers are removed, drying treatment may be performed in order to remove water contained in the EL layer113R, the EL layer113G, and the EL layer113B and water adsorbed on the surface of the EL layer113R, the surface of the EL layer113G, and the surface of the EL layer113B. For example, heat treatment in an inert gas atmosphere or a reduced-pressure atmosphere can be performed. The heat treatment can be performed at a substrate temperature higher than or equal to 50° C., and lower than or equal to 200° C., preferably higher than or equal to 60° C., and lower than or equal to 150° C., further preferably higher than or equal to 70° C., and lower than or equal to 120° C. Employing a reduced-pressure atmosphere is preferable, in which case drying at a lower temperature is possible.

Next, as illustrated inFIG.26D, the insulating film125fto be the insulating layer125later is formed to cover the EL layer113R, the EL layer113G, and the EL layer113B and the mask layer118R, the mask layer118G, and the mask layer118B.

As described later, an insulating film to be the insulating layer127later is formed in contact with the upper surface of the insulating film125f. Therefore, the upper surface of the insulating film125fpreferably has high affinity for a material used for the insulating film, e.g., a photosensitive resin composition containing an acrylic resin. To improve the affinity, surface treatment is preferably performed so that the upper surface of the insulating film125fis made hydrophobic or its hydrophobic properties are improved. For example, it is preferable to perform the treatment using a silylation agent such as HMDS. By making the upper surface of the insulating film125fhydrophobic in this manner, the insulating film127fcan be formed with high adhesion. Note that the above-described hydrophobization treatment may be performed as the surface treatment.

Then, as illustrated inFIG.27A, an insulating film127fto be the insulating layer127later is formed over the insulating film125f.

The insulating film125fand the insulating film127fare preferably formed by a formation method that causes less damage to the EL layer113R, the EL layer113G, and the EL layer113B. The insulating film125f, which is formed in contact with the side surfaces of the EL layer113R, the EL layer113G, and the EL layer113B, is particularly preferably formed by a method that is less likely to damage the EL layer113R, the EL layer113G, and the EL layer113B than the method of forming the insulating film127f.

In addition, the insulating film125fand the insulating film127fare each formed at a temperature lower than the upper temperature limit of the EL layer113R, the EL layer113G, and the EL layer113B. When the substrate temperature at the time when the insulating film125fis formed is increased, the formed insulating film125f, even with a small thickness, can have a low impurity concentration and a high barrier property against at least one of water and oxygen.

The substrate temperature at the time of forming the insulating film125fand the insulating film127fis preferably higher than or equal to 60° C., higher than or equal to 80° C., higher than or equal to 100° C., or higher than or equal to 120° C., and lower than or equal to 200° C., lower than or equal to 180° C., lower than or equal to 160° C., lower than or equal to 150° C., or lower than or equal to 140° C.

As the insulating film125f, an insulating film is preferably formed within the above substrate temperature range to have a thickness greater than or equal to 3 nm, greater than or equal to 5 nm, or greater than or equal to 10 nm and less than or equal to 200 nm, less than or equal to 150 nm, less than or equal to 100 nm, or less than or equal to 50 nm.

The insulating film125fis preferably formed by an ALD method, for example. The use of an ALD method is preferable, in which case damage by the deposition is reduced and a film with good coverage can be deposited. As the insulating film125f, an aluminum oxide film is preferably formed by an ALD method, for example.

Alternatively, the insulating film125fmay be formed by a sputtering method, a CVD method, or a PECVD method, each of which has a higher deposition rate than an ALD method. In that case, a highly reliable display device can be manufactured with high productivity.

The insulating film127fis preferably formed by the aforementioned wet film formation method. The insulating film127fis preferably formed by spin coating using a photosensitive material, for example, and preferably formed using specifically a photosensitive resin composition containing an acrylic resin.

The insulating film127fis preferably formed using a resin composition containing a polymer, an acid-generating agent, and a solvent, for example. The polymer is formed using one or more kinds of monomers and has a structure where one or more kinds of structural units (also referred to as building blocks) are repeated regularly or irregularly. As the acid-generating agent, one or both of a compound that generates an acid by light irradiation and a compound that generates an acid by heating can be used. The resin composition may also include one or more of a photosensitizing agent, a sensitizer, a catalyst, an adhesive aid, a surface-active agent, and an antioxidant.

Heat treatment (also referred to as prebaking) is preferably performed after the insulating film127fis formed. The heat treatment is performed at a temperature lower than the upper temperature limit of the EL layer113R, the EL layer113G, and the EL layer113B. The substrate temperature in the heat treatment is preferably higher than or equal to 50° C., and lower than or equal to 200° C., further preferably higher than or equal to 60° C., and lower than or equal to 150° C., still further preferably higher than or equal to 70° C., and lower than or equal to 120° C. Accordingly, a solvent contained in the insulating film127fcan be removed.

Then, part of the insulating film127fis exposed to visible light or ultraviolet rays. Here, when a positive photosensitive resin composition containing an acrylic resin is used for the insulating film127f, a region where the insulating layer127is not formed in a later step is irradiated with visible light or ultraviolet rays. The insulating layer127is formed in regions that are interposed between any two of the conductive layer112R, the conductive layer112G, and the conductive layer112B and around the conductive layer112C. Accordingly, irradiation with visible light or ultraviolet rays is performed over the conductive layer112R, over the conductive layer112G, over the conductive layer112B, and over the conductive layer112C. Note that when a negative photosensitive material is used for the insulating film127f, the region where the insulating layer127is to be formed is irradiated with visible light or ultraviolet rays.

The width of the insulating layer127formed later can be controlled in accordance with the exposed region of the insulating film127f. In this embodiment, processing is performed such that the insulating layer127includes a portion overlapping with the upper surface of the conductive layer111.

Light used for the exposure preferably includes the i-line (wavelength: 365 nm). The light used for the exposure may include at least one of the g-line (wavelength: 436 nm) and the h-line (wavelength: 405 nm).

Here, when a barrier insulating layer against oxygen such as an aluminum oxide film, for example, is provided as one or both of the mask layer118and the insulating film125f, diffusion of oxygen into the EL layer113R, the EL layer113G, and the EL layer113B can be inhibited. When the EL layer is irradiated with light (visible light rays or ultraviolet rays), an organic compound contained in the EL layer is brought into an excited state and a reaction between the organic compound and oxygen in the atmosphere is promoted in some cases. Specifically, when the EL layer is irradiated with light (visible light rays or ultraviolet rays) in an atmosphere containing oxygen, oxygen might be bonded to the organic compound contained in the EL layer. By providing the mask layer118and the insulating film125fover the island-shaped EL layer, bonding of oxygen in the atmosphere to the organic compound contained in the EL layer can be reduced.

Next, as illustrated in FIG.27B1and FIG.27B2, development is performed to remove the exposed region of the insulating film127f, so that an insulating layer127ais formed. FIG.27B2is an enlarged view of the end portions of the EL layer113G and the insulating layer127aillustrated in FIG.27B1and their vicinity. The insulating layer127ais formed in regions that are interposed between any two of the conductive layer112R, the conductive layer112G, and the conductive layer112B and a region surrounding the conductive layer112C. Here, when an acrylic resin is used for the insulating film127f, a developer is preferably an alkaline solution and can be TMAH, for example.

Then, a residue (scum) due to the development may be removed. For example, the residue can be removed by ashing using oxygen plasma.

Etching may be performed so that the surface level of the insulating layer127ais adjusted. The insulating layer127amay be processed by ashing using oxygen plasma, for example. In the case where a non-photosensitive material is used for the insulating film127f, the surface level of the insulating film127fcan be adjusted by the ashing, for example.

Next, as illustrated inFIG.28AandFIG.28B, etching treatment is performed with the insulating layer127aas a mask to remove part of the insulating film125fand reduce the thickness of part of the mask layer118R, the mask layer118G, and the mask layer118B. Thus, the insulating layer125is formed under the insulating layer127a. Moreover, the surfaces of the thin portions in the mask layer118R, the mask layer118G, and the mask layer118B are exposed.FIG.28Bis an enlarged view of the end portions of the EL layer113G and the insulating layer127aillustrated inFIG.28Aand their vicinity. Note that the etching treatment using the insulating layer127aas a mask may be hereinafter referred to as first etching treatment.

The first etching treatment can be performed by dry etching or wet etching. Note that the insulating film125fis preferably formed using a material similar to that of the mask layer118R, the mask layer118G, and the mask layer118B, in which case the first etching treatment can be performed collectively.

By etching using the insulating layer127awith a tapered side surface as a mask as illustrated inFIG.28B, the side surface of the insulating layer125and upper end portions of the side surfaces of the mask layer118R, the mask layer118G, and the mask layer118B can be made to have a tapered shape relatively easily.

In the case of performing dry etching, a chlorine-based gas is preferably used. As the chlorine-based gas, one selected from Cl2, BCl3, SiCl4, CCl4, and the like or a mixture of two or more selected therefrom can be used. Moreover, one selected from an oxygen gas, a hydrogen gas, a helium gas, an argon gas, and the like or a mixture of two or more selected therefrom can be added to the chlorine-based gas as appropriate. By the dry etching, the thin regions of the mask layer118R, the mask layer118G, and the mask layer118B can be formed with favorable in-plane uniformity.

As a dry etching apparatus, a dry etching apparatus including a high-density plasma source can be used. As the dry etching apparatus including a high-density plasma source, an inductively coupled plasma (ICP) etching apparatus can be used, for example. Alternatively, a capacitively coupled plasma (CCP) etching apparatus including parallel plate electrodes can be used. The capacitively coupled plasma etching apparatus including the parallel plate electrodes may have a structure in which a high-frequency voltage is applied to one of the parallel plate electrodes. Alternatively, a structure may be employed in which different high-frequency voltages are applied to one of the parallel plate electrodes. Alternatively, a structure may be employed in which high-frequency voltages with the same frequency are applied to the parallel plate electrodes. Alternatively, a structure may be employed in which high-frequency voltages with different frequencies are applied to the parallel plate electrodes. Alternatively, a structure may be employed in which high-frequency voltages with different frequencies are applied to the parallel plate electrodes.

In the case of performing dry etching, a by-product or the like generated by the dry etching might be deposited on the upper surface and the side surface of the insulating layer127a, for example. Thus, a component contained in the etching gas, a component contained in the insulating film125f, components contained in the mask layer118R, the mask layer118G, and the mask layer118B, or the like might be contained in the insulating layer127after the display device is completed.

The first etching treatment is preferably performed by wet etching. Using a wet etching method can reduce damage to the EL layer113R, the EL layer113G, and the EL layer113B, as compared to the case of using a dry etching method. Wet etching can be performed using an alkaline solution, for example. For instance, TMAH, which is an alkaline solution, is preferably used for wet etching of an aluminum oxide film. In that case, paddle wet etching can be performed. Note that the insulating film125fis preferably formed using a material similar to that of the mask layer118R, the mask layer118G, and the mask layer118B, in which case the etching treatment can be performed collectively.

As illustrated inFIG.28AandFIG.28B, the mask layer118R, the mask layer118G, and the mask layer118B are not removed completely by the first etching treatment, and the etching treatment is stopped when the thickness of the mask layer118R, the mask layer118G, and the mask layer118B is reduced. The corresponding mask layer118R, mask layer118G, and mask layer118B are left over the EL layer113R, the EL layer113G, and the EL layer113B in this manner, whereby the EL layer113R, the EL layer113G, and the EL layer113B can be inhibited from being damaged by processing in a later step.

Although the mask layer118R, the mask layer118G, and the mask layer118B are thinned inFIG.28AandFIG.28B, the present invention is not limited thereto. For example, depending on the thickness of the insulating film125fand the thicknesses of the mask layer118R, the mask layer118G, and the mask layer118B, the first etching treatment may be stopped before the insulating film125fis processed into the insulating layer125. Specifically, the first etching treatment may be stopped only after reducing the thickness of part of the insulating film125f. In the case where the insulating film125fis formed with a material similar to those of the mask layer118R, the mask layer118G, and the mask layer118B, the boundary between the insulating film125fand the mask layer118R, the mask layer118G, and the mask layer118B might be unclear. Consequently, whether the insulating layer125is formed and whether the mask layer118R, the mask layer118G, and the mask layer118B are thinned cannot be determined in some cases.

AlthoughFIG.28AandFIG.28Bshow an example in which the shape of the insulating layer127ais not changed from that in FIG.27B1and FIG.27B2, the present invention is not limited thereto. For example, the end portion of the insulating layer127amay sag and cover the end portion of the insulating layer125. As another example, the end portion of the insulating layer127amay be in contact with the upper surfaces of the mask layer118R, the mask layer118G, and the mask layer118B. As described above, when light exposure is not performed on the insulating layer127aafter the development, the shape of the insulating layer127amay be likely to change.

Next, light exposure is preferably performed on the entire substrate so that the insulating layer127ais irradiated with visible light or ultraviolet rays. The energy density for the light exposure is preferably greater than 0) mJ/cm2and less than or equal to 800 mJ/cm2, further preferably greater than 0) mJ/cm2and less than or equal to 500 mJ/cm2. Performing such light exposure after the development can sometimes increase the degree of transparency of the insulating layer127a. In addition, it is sometimes possible to lower the substrate temperature required for subsequent heat treatment for changing the shape of the insulating layer127ainto a tapered shape.

Meanwhile, as described later, when light exposure is not performed on the insulating layer127a, it sometimes becomes easy to change the shape of the insulating layer127aor change the shape of the insulating layer127to a tapered shape in a later step. Thus, in some cases, it is preferable not to perform light exposure of the insulating layer127aafter the development.

For example, in the case where a light curable resin is used for the insulating layer127a, light exposure of the insulating layer127acan start polymerization and cure the insulating layer127a. Note that without performing light exposure of the insulating layer127aat this stage, at least one of after-mentioned post-baking and second etching treatment may be performed while the insulating layer127aremains in a state where its shape is relatively easily changed. Thus, generation of unevenness in the formation surface of the common layer114and the common electrode115can be inhibited and accordingly step disconnection of the common layer114and the common electrode115can be inhibited. Note that light exposure may be performed after the development but before the first etching treatment. Meanwhile, depending on the material (e.g., a positive-type material) of the insulating layer127aand the first etching treatment conditions, the insulating layer127athat has been subjected to light exposure might be dissolved in a chemical solution during the first etching treatment. For this reason, light exposure is preferably performed after the first etching treatment but before post-baking. Hence, the insulating layer127ahaving an intended shape can be stably formed with high reproducibility.

Here, irradiation with visible light or ultraviolet rays is preferably performed in an atmosphere containing no oxygen or an atmosphere containing a small amount of oxygen. For example, the irradiation with visible light or ultraviolet rays is preferably performed in an inert gas atmosphere such as a nitrogen atmosphere or a reduced-pressure atmosphere. If the irradiation with visible light or ultraviolet rays is performed in an atmosphere containing a large amount of oxygen, the compound contained in the EL layer113might be oxidized and the properties of the EL layer113might be changed. By contrast, by performing the irradiation with visible light or ultraviolet rays in an atmosphere containing no oxygen or an atmosphere containing a small amount of oxygen, a change of the properties of the EL layer can be inhibited: hence, a more highly reliable display device can be provided.

Then, as illustrated inFIG.29AandFIG.29B, heat treatment (also referred to as post-baking) is performed. As illustrated inFIG.29AandFIG.29B, the heat treatment can change the insulating layer127ainto the insulating layer127with a tapered side surface. As described above, in some cases, the insulating layer127ais already changed in shape and has a tapered side surface at the time when the first etching treatment is finished. The heat treatment is performed at a temperature lower than the upper temperature limit of the EL layer113. The heat treatment can be performed at a substrate temperature higher than or equal to 50° C., and lower than or equal to 200° C., preferably higher than or equal to 60° C., and lower than or equal to 150° C., further preferably higher than or equal to 70° C., and lower than or equal to 130° C. The heating atmosphere may be an air atmosphere or an inert gas atmosphere. Moreover, the heating atmosphere may be an atmospheric-pressure atmosphere or a reduced-pressure atmosphere. The heat treatment is preferably performed in a reduced-pressure atmosphere, in which case drying at a lower temperature is possible. The heat treatment in this step is preferably performed at a higher substrate temperature than the heat treatment (pre-baking) after the formation of the insulating film127f. Accordingly, adhesion between the insulating layer127and the insulating layer125can be improved, and corrosion resistance of the insulating layer127can be increased.FIG.29Bis an enlarged view of the end portions of the layer113G and the insulating layer127illustrated inFIG.29Aand their vicinities.

As described above, a material with high heat resistance is used for the light-emitting element of the display device of one embodiment of the present invention. Therefore, the temperature of the pre-baking and the temperature of the post-baking can each be higher than or equal to 100° C., higher than or equal to 120° C., or higher than or equal to 140° C. Thus, adhesion between the insulating layer127and the insulating layer125can be further improved, and the corrosion resistance of the insulating layer127can be further increased. Moreover, the range of choices for materials that can be used for the insulating layer127can be widened. By adequately removing the solvent and the like included in the insulating layer127, for example, entry of impurities such as water and oxygen into the EL layer113can be inhibited.

When the mask layer118R, the mask layer118G, and the mask layer118B are not completely removed by the first etching treatment and the mask layer118R, the mask layer118G, and the mask layer118B with reduced thicknesses remain, the EL layer113R, the EL layer113G, and the EL layer113B can be inhibited from being damaged and deteriorating in the post-baking, for example. Thus, the reliability of the light-emitting element can be increased.

As illustrated inFIG.7AandFIG.7B, the side surface of the insulating layer127might have a concave shape depending on the material of the insulating layer127, and the temperature, time, and atmosphere of the post-baking. For example, the insulating layer127is more likely to be changed in shape to have a concave shape as the post-baking is performed at higher temperature or for a longer time. In addition, as described above, the insulating layer127is sometimes likely to be changed in shape at the time of the post-baking, in the case where light exposure is not performed on the insulating layer127aafter development.

Next, as illustrated inFIG.30AandFIG.30B, etching treatment is performed with the insulating layer127as a mask to remove part of the mask layer118R, the mask layer118G, and the mask layer118B. Note that part of the insulating layer125is also removed in some cases. Thus, openings are formed in the mask layer118R, the mask layer118G, and the mask layer118B, and the upper surfaces of the EL layer113R, the EL layer113G, and the EL layer113B and the conductive layer112C are exposed. Note thatFIG.30Bis an enlarged view of the end portions of the EL layer113G and the insulating layer127illustrated inFIG.30Aand their vicinities. Note that the etching treatment using the insulating layer127as a mask may be hereinafter referred to as second etching treatment.

The end portion of the insulating layer125is covered with the insulating layer127.FIG.30AandFIG.30Billustrate an example where part of the end portion of the mask layer118G, specifically, a tapered portion formed by the first etching treatment, is covered with the insulating layer127and the tapered portion formed by the second etching treatment is exposed. That is, the structure inFIG.30AandFIG.30Bcorresponds to that inFIG.5AandFIG.5B.

If the first etching treatment is not performed and the insulating layer125and the mask layer are collectively etched after the post-baking, the insulating layer125and the mask layer under the end portion of the insulating layer127may be eliminated by side etching and a cavity may be formed. The cavity causes unevenness in the formation surface of the common layer114and the common electrode115, so that disconnection is likely to occur in the common layer114and the common electrode115. Even when a cavity is formed owing to side etching of the insulating layer125and the mask layer by the first etching treatment, the post-baking performed subsequently can make the insulating layer127fill the cavity. After that, the mask layer having a smaller thickness is etched by the second etching treatment: thus, the amount of side etching decreases, a cavity is less likely to be formed, and even if a cavity is formed, it can be extremely small. Therefore, the formation surface of the common layer114and the common electrode115can be flatter.

Note that as illustrated inFIG.6AandFIG.6BorFIG.8A, andFIG.8B, the insulating layer127may cover the entire end portion of the mask layer118G. For example, the end portion of the insulating layer127sags and covers the end portion of the mask layer118G in some cases. For another example, the end portion of the insulating layer127may be in contact with the upper surface of at least one of the EL layer113R, the EL layer113G, and the EL layer113B. As described above, in the case where light exposure is not performed on the insulating layer127aafter development, the shape of the insulating layer127is likely to change in some cases.

The second etching treatment is performed by wet etching. Using a wet etching method can reduce damage to the EL layer113R, the EL layer113G, and the EL layer113B, as compared to the case of using a dry etching method. The wet etching can be performed using an alkaline solution such as TMAH, for example.

Meanwhile, in the case where the second etching treatment is performed by a wet etching method and gaps due to, for example, poor adhesion between the EL layer113and another layer exist at the interface between the EL layer113and the mask layer118, the interface between the EL layer113and the inorganic insulating layer125, and the interface between the EL layer113and the insulating layer105, the chemical solution used in the second etching treatment sometimes enters the gaps to come into contact with the pixel electrode. Here, when the chemical solution comes into contact with both the conductive layer111and the conductive layer112, one of the conductive layer111and the conductive layer112that has a lower spontaneous potential than the other suffers from galvanic corrosion in some cases. For example, when the conductive layer111is formed using aluminum and the conductive layer112is formed using indium tin oxide, the conductive layer112sometimes corrodes. As a result, the yield of the display device decreases in some cases. This degrades the reliability of the display device in some cases.

In the method of manufacturing the display device of one embodiment of the present invention, the conductive layer112is formed to cover the upper surface and the side surface of the conductive layer111as described above. Thus, even when gaps exist at the interface between the EL layer113and the mask layer118, the interface between the EL layer113and the inorganic insulating layer125, and the interface between the EL layer113and the insulating layer105, for example, the chemical solution can be prevented from coming into contact with the conductive layer111in the second etching treatment. Thus, corrosion of the pixel electrode, e.g., the conductive layer112, can be inhibited. As described above, the method of manufacturing the display device of one embodiment of the present invention can achieve high yield. In addition, the method of manufacturing the display device of one embodiment of the present invention can inhibit generation of defects.

As described above, by providing the insulating layer127, the insulating layer125, the mask layer118R, the mask layer118G, and the mask layer118B, a connection defect due to a disconnected portion and an increase in electrical resistance due to a locally thinned portion can be inhibited from occurring in the common layer114and the common electrode115between the light-emitting elements. Thus, the display device of one embodiment of the present invention can have improved display quality.

Heat treatment may be performed after part of the EL layer113R, the EL layer113G, and the EL layer113B is exposed. The heat treatment can remove water contained in the EL layer113, water adsorbed onto a surface of the EL layer113, and the like. The shape of the insulating layer127may be changed by the heat treatment. Specifically, the insulating layer127may be extended to cover at least one of the end portion of the insulating layer125, the end portions of the mask layer118R, the mask layer118G, and the mask layer118B, and the upper surfaces of the EL layer113R, the EL layer113G, and the EL layer113B. For example, the insulating layer127may have a shape illustrated inFIG.6AandFIG.6B. For example, heat treatment in an inert gas atmosphere or a reduced-pressure atmosphere can be performed. The heat treatment can be performed at a substrate temperature higher than or equal to 50° C., and lower than or equal to 200° C., preferably higher than or equal to 60° C., and lower than or equal to 150° C., further preferably higher than or equal to 70° C., and lower than or equal to 120° C. The heat treatment is preferably performed in a reduced-pressure atmosphere, in which case dehydration at a lower temperature is possible. Note that the temperature range of the heat treatment is preferably set as appropriate in consideration of the upper temperature limit of the EL layer113. In consideration of the upper temperature limit of the EL layer113, temperatures from 70° C. to 120° C. inclusive are particularly preferable in the above temperature range.

Then, as illustrated inFIG.31A, the common layer114is formed over the EL layer113R, over the EL layer113G, over the EL layer113B, over the conductive layer112C, and over the insulating layer127. The common layer114can be formed by a method such as an evaporation method (including a vacuum evaporation method), a transfer method, a printing method, an inkjet method, or a coating method.

Then, as illustrated inFIG.31A, the common electrode115is formed over the common layer114. The common electrode115can be formed by a method such as a sputtering method or a vacuum evaporation method. Alternatively, the common electrode115may be formed in such a manner that a film formed by an evaporation method and a film formed by a sputtering method are stacked.

The common electrode115can be formed successively without a process such as etching between formations of the common layer114and the common electrode115. For example, after the common layer114is formed in a vacuum, the common electrode115can be formed in a vacuum without exposing the substrate to the air. In other words, the common layer114and the common electrode115can be successively formed in a vacuum. Accordingly, the lower surface of the common electrode115can be a clean surface, as compared to the case where the common layer114is not provided in the display device100. Thus, the light-emitting element130can have high reliability and favorable characteristics.

Next, the protective layer131is formed over the common electrode115, as illustrated inFIG.31B. The protective layer131can be formed by a vacuum evaporation method, a sputtering method, a CVD method, an ALD method, or the like.

Subsequently, the substrate120is attached onto the protective layer131with the resin layer122, whereby the display device having the structure illustrated inFIG.2Aor the structure illustrated inFIG.18Acan be manufactured. In the method of manufacturing the display device of one embodiment of the present invention, the conductive layer112is formed to cover the upper surface and the side surface of the conductive layer111as described above, which can increase the yield of the display device and inhibit generation of defects.

Here, after the insulating layer127is formed by the post-baking illustrated inFIG.29AandFIG.29B, the insulating layer127may be exposed to light. For example, the insulating layer127may be exposed to light in the case where the aforementioned light exposure is not performed on the insulating layer127a. For example, the insulating layer127may be exposed to light after the second etching treatment illustrated inFIG.30AandFIG.30Bbut before the formation of the common layer114illustrated inFIG.31A. Alternatively, the insulating layer127may be exposed to light after the formation of the common electrode115illustrated inFIG.31Abut before the formation of the protective layer131illustrated inFIG.31B. Alternatively, the insulating layer127may be exposed to light after the formation of the protective layer131illustrated in FIG.31B. Here, for example, the conditions similar to those for the aforementioned light exposure of the insulating layer127acan be used as the conditions for light exposure of the insulating layer127. Note that light exposure of the insulating layer127aand light exposure of the insulating layer127may be omitted, performed only once in total, or performed two or more times in total.

For example, in the case where a photocurable resin is used for the insulating layer127, light exposure of the insulating layer127can cure the insulating layer127. Consequently, deformation of the insulating layer127can be inhibited. Thus, peeling of the layer over the insulating layer127can be inhibited, for example. Consequently, the display device of one embodiment of the present invention can be a highly reliable display device.

As described above, in the method of manufacturing a display device of one embodiment of the present invention, the island-shaped EL layer113R, the island-shaped EL layer113G, and the island-shaped EL layer113B are formed not by using a fine metal mask but by processing a film formed over the entire surface: thus, the island-shaped layers can be formed to have a uniform thickness. Accordingly, a high-resolution display device or a display device with a high aperture ratio can be achieved. Furthermore, even when the resolution or the aperture ratio is high and the distance between the subpixels is extremely short, the EL layer113R, the EL layer113G, and the EL layer113B can be inhibited from being in contact with each other in adjacent subpixels. As a result, generation of a leakage current between the subpixels can be inhibited. This can prevent crosstalk due to unintended light emission, so that a display device with extremely high contrast can be achieved.

The insulating layer127having a tapered end portion and being provided between adjacent island-shaped EL layers113can inhibit occurrence of disconnection and prevent formation of a locally thinned portion in the common electrode115at the time of forming the common electrode115. Thus, a connection defect due to a disconnected portion and an increase in electric resistance due to a locally thinned portion can be inhibited from occurring in the common layer114and the common electrode115. Hence, the display device of one embodiment of the present invention achieves both high resolution and high display quality.

Manufacturing Method Example 2

A manufacturing method example of the display device100having the structure illustrated inFIG.10and the structure illustrated inFIG.18Cwill be described below with reference to drawings. Note that steps different from those in the method described with FIG.24A toFIG.31Bwill be mainly described, and the description of the same steps as those in the method described withFIG.24AtoFIG.31Bwill be omitted as appropriate.

FIG.32AtoFIG.32Cillustrate steps similar to those inFIG.24AtoFIG.24C.

FIG.32D1is an enlarged view of a cross section along the line B1-B2 shown inFIG.32C. In the example illustrated in FIG.32D1, the conductive film112fincludes a region overlapping with the conductive layer109.

FIG.32D2illustrates a modification example of FIG.32D1, and in the example, the conductive film112fdoes not overlap with the conductive layer109. For example, after the conductive film112fis formed as illustrated inFIG.32C, the conductive film112fis partly removed in a region along the line B1-B2, whereby a structure illustrated in FIG.32D2can be fabricated. When a step illustrated in FIG.32D2is performed, the fabricated structure along the line B1-B2 in the display device100becomes the structure illustrated inFIG.18A, for example.

For example, the conductive film112fprovided in the region overlapping with the conductive layer109is removed so that the conductive layer112C formed in a later step does not overlap with the conductive layer109. As a result, generation of parasitic capacitance can be inhibited as described above, for example. It may be assumed that the conductive layer112C is formed by the step illustrated in FIG.32D2. That is, in FIG.32D2, the conductive film112fmay be replaced with the conductive layer112C.

The manufacturing method example of the display device100is described below assuming that the step illustrated in FIG.32D2is not performed. However, the following description of the manufacturing method example can be referred to for the case where the step illustrated in FIG.32D2is performed.

Next, hydrophobization treatment is preferably performed on the conductive film112f, as described above.

Subsequently, as illustrated inFIG.33A, the EL film113Rf to be the EL layer113R later is formed over the conductive film112fby a method similar to the method illustrated inFIG.25A. After that, the mask film118Rf to be the mask layer118R later and the mask film119Rf to be the mask layer119R later are sequentially formed over the EL film113Rf and over the conductive film112fby a method similar to the method illustrated inFIG.25A.

Next, as illustrated inFIG.33A, the resist mask190R is formed over the mask film119Rf by a method similar to the method illustrated inFIG.25A. The resist mask190R is provided at a position overlapping with the conductive layer111R. The resist mask190R can also be provided at a position overlapping with the conductive layer111C.

Subsequently, as illustrated inFIG.33AandFIG.33B, part of the mask film119Rf is removed using the resist mask190R by a method similar to the method illustrated inFIG.25AandFIG.25B, whereby the mask layer119R is formed. The mask layer119R remains over the conductive layer111R and over the conductive layer111C. After that, the resist mask190R is removed by a method similar to the method illustrated inFIG.25AandFIG.25B. Next, by a method similar to the method illustrated inFIG.25AandFIG.25B, part of the mask film118Rf is removed using the mask layer119R as a mask, whereby the mask layer118R is formed.

Next, as illustrated inFIG.33AandFIG.33B, the EL film113Rf is processed by a method similar to the method illustrated inFIG.25AandFIG.25B, whereby the EL layer113R is formed. For example, part of the EL film113Rf is removed using the mask layer119R and the mask layer118R as a mask to form the EL layer113R. Accordingly, as illustrated inFIG.33B, the stacked-layer structure of the EL layer113R, the mask layer118R, and the mask layer119R remains over the conductive film112fto include a region overlapping with the conductive layer111R. In a region where the mask layer119R is not provided, the conductive film112fis exposed.

The resist mask190R is preferably provided to cover the area from the end portion of the EL layer113R to the end portion of the conductive layer111C (the end portion closer to the EL layer113R) in the cross section B1-B2. Thus, as illustrated inFIG.33B, the mask layers118R and119R are provided to cover the area from the end portion of the EL layer113R to the end portion of the conductive layer111C (the end portion closer to the EL layer113R) in the cross section B1-B2. Hence, the conductive film112fcan be inhibited from being exposed in the cross section B1-B2, for example. This can inhibit the conductive film112f, the insulating layer105, the insulating layer104, and the insulating layer103from being partly removed by etching, for example, and thus inhibit the conductive layer109from being exposed. Thus, unintentional electrical connection between the conductive layer109and another conductive layer can be inhibited. For example, a short circuit between the conductive layer109and the common electrode115formed in a later step can be inhibited.

Next, hydrophobic treatment for the conductive film112f, for example, is preferably performed. At the time of processing the EL film113Rf, the surface of the conductive film112fchanges to have hydrophilic properties in some cases, for example. The hydrophobization treatment for the conductive film112f, for example, can increase the adhesion between the conductive film112fand a layer to be formed in a later step (which is the EL layer113G here) and inhibit peeling. Note that the hydrophobization treatment is not necessarily performed.

Subsequently, as illustrated inFIG.33C, the EL film113Gf to be the EL layer113G later is formed over the conductive film112fand over the mask layer119R by a method similar to the method illustrated inFIG.25C.

Then, as illustrated inFIG.33C, the mask film118Gf to be the mask layer118G later and the mask film119Gf to be the mask layer119G later are sequentially formed over the EL film113Gf and over the mask layer119R by a method similar to the method illustrated inFIG.25C. After that, a resist mask190G is formed.

The resist mask190G is provided at a position overlapping with the conductive layer111G.

Subsequently, as illustrated inFIG.33CandFIG.33D, part of the mask film119Gf is removed using the resist mask190G by a method similar to the method illustrated inFIG.25Cand

FIG.25D, whereby the mask layer119G is formed. The mask layer119G remains over the conductive layer111G. After that, the resist mask190G is removed by a method similar to the method illustrated inFIG.25CandFIG.25D. Next, by a method similar to the method illustrated inFIG.25CandFIG.25D, part of the mask film118Gf is removed using the mask layer119G as a mask, whereby the mask layer118G is formed. Next, the EL film113Gf is processed to form the EL layer113G by a method similar to the method illustrated inFIG.25CandFIG.25D. For example, part of the EL film113Gf is removed using the mask layer119G and the mask layer118G as a mask to form the EL layer113G.

Accordingly, as illustrated inFIG.33D, the stacked-layer structure of the EL layer113G, the mask layer118G, and the mask layer119G remains over the conductive layer111G. The mask layer119R is exposed, and the conductive film112fis exposed in regions where neither the mask layer119R nor the mask layer119G is provided.

Next, hydrophobic treatment for the conductive film112f, for example, is preferably performed. At the time of processing the EL film113Gf, the surface of the conductive film112fchanges to have hydrophilic properties in some cases, for example. The hydrophobization treatment for the conductive film112f, for example, can increase the adhesion between the conductive film112fand a layer to be formed in a later step (which is the EL layer113B here) and inhibit peeling. Note that the hydrophobization treatment is not necessarily performed.

Subsequently, as illustrated inFIG.34A, the EL film113Bf to be the EL layer113B later is formed over the conductive film112f, over the mask layer119R, and over the mask layer119G by a method similar to the method illustrated inFIG.26A.

Then, as illustrated inFIG.34A, the mask film118Bf to be the mask layer118B later and the mask film119Bf to be the mask layer119B later are sequentially formed over the EL film113Bf and over the mask layer119R by a method similar to the method illustrated inFIG.26A. After that, a resist mask190B is formed.

The resist mask190B is provided at a position overlapping with the conductive layer111B.

Subsequently, as illustrated inFIG.34AandFIG.34B, part of the mask film119Bf is removed using the resist mask190B, whereby the mask layer119B is formed. The mask layer119B remains over the conductive layer111B. After that, the resist mask190B is removed. Then, part of the mask film118Bf is removed using the mask layer119B as a mask, whereby the mask layer118B is formed. Next, the EL film113Bf is processed to form the EL layer113B. For example, part of the EL film113Bf is removed using the mask layer119B and the mask layer118B as a mask to form the EL layer113B.

Accordingly, as illustrated inFIG.34B, the stacked-layer structure of the EL layer113B, the mask layer118B, and the mask layer119B remains over the conductive layer111B. The mask layer119R and the mask layer119G are exposed, and the conductive film112fis exposed in regions where none of the mask layer119R, the mask layer119G, and the mask layer119B is provided.

Next, as illustrated inFIG.34BandFIG.34C, part of the conductive film112fis removed by an etching method using the mask layer119R, the mask layer119G, and the mask layer119B as a mask, for example. Consequently, the conductive layer112R, the conductive layer112G, the conductive layer112B, and the conductive layer112C are formed. In the case where a conductive oxide is used for the conductive film112f, the conductive film112fcan be removed by a wet etching method, for example. The conductive layer112is formed to cover the upper surface and the side surface of the conductive layer111. In the case where the conductive layer112has the structure illustrated in FIG.2B2, a metal material is used for the conductive layer112a, and a conductive oxide is used for the conductive layer112b, for example, a conductive film to be the conductive layer112acan be partly removed by a dry etching method after a conductive film to be the conductive layer112bis partly removed by a wet etching method.

Next, d as illustrated inFIG.35A, the mask layer119R, the mask layer119G, and the mask layer119B are preferably remove, by a method similar to the method illustrated inFIG.26C.

Next, as illustrated inFIG.35B, the insulating film125fto be the insulating layer125later is formed to cover the conductive layer112R, the conductive layer112G, the conductive layer112B, EL layer113R, EL layer113G, EL layer113B, the mask layer118R, the mask layer118G, and the mask layer118B by a method similar to the method illustrated inFIG.26D.

FIG.35C,FIG.36AtoFIG.36D,FIG.37A, andFIG.37Bshow steps similar to those inFIG.27A, FIG.27B1,FIG.28A,FIG.29A,FIG.30A,FIG.31A, andFIG.31B. After the step illustrated inFIG.37B, the substrate120is attached onto the protective layer131with the resin layer122, whereby the display device having the structure illustrated inFIG.10and the structure illustrated inFIG.18Ccan be manufactured.

Manufacturing Method Example 3

A manufacturing method example of the display device100having the structure illustrated inFIG.14and the structure illustrated inFIG.18Ewill be described below with reference to drawings. Note that steps different from those in the method described withFIG.24AtoFIG.31Bwill be mainly described, and the description of the same steps as those in the method described withFIG.24AtoFIG.31Bwill be omitted as appropriate.

First, steps similar to the steps illustrated inFIG.24AtoFIG.24Dare performed. Next, as illustrated inFIG.38A, an EL film113Rf to be the EL layer113R later is formed over conductive layer112R, over the conductive layer112G, over the conductive layer112B, and over the insulating layer105by a method similar to the method illustrated inFIG.25A. The EL film113Rf includes a film113R1fto be the light-emitting unit113R1later, a charge-generation film113R2fto be the charge-generation layer113R2later, and a film113R3fto be the light-emitting unit113R3later. InFIG.38A, the charge-generation film113Rf2is indicated by a dashed line.

Next, as illustrated inFIG.38A, the mask film118Rf to be the mask layer118R later and the mask film119Rf to be the mask layer119R later are sequentially formed over the EL film113Rf, over the conductive layer112C, and over the insulating layer105by a method similar to the method illustrated inFIG.25A. Next, as illustrated inFIG.38A, the resist mask190R is formed over the mask film119Rf by a method similar to the method illustrated inFIG.25A.

Subsequently, as illustrated inFIG.38AandFIG.38B, part of the mask film119Rf is removed using the resist mask190R by a method similar to the method illustrated inFIG.25AandFIG.25B, whereby the mask layer119R is formed. The mask layer119R remains over the conductive layer111R and over the conductive layer111C. After that, the resist mask190R is removed by a method similar to the method illustrated inFIG.25AandFIG.25B. Next, by a method similar to the method illustrated inFIG.25AandFIG.25B, part of the mask film118Rf20) is removed using the mask layer119R as a mask, whereby the mask layer118R is formed.

Next, as illustrated inFIG.38AandFIG.38B, the EL film113Rf is processed by a method similar to the method illustrated inFIG.25AandFIG.25B, whereby the EL layer113R is formed. For example, part of the EL film113Rf is removed using the mask layer119R and the mask layer118R as a mask to form the EL layer113R. As described above, the EL layer113R includes the light-emitting unit113R1, the charge-generation layer113R2over the light-emitting unit113R1, and the light-emitting unit113R3over the charge-generation layer113R2, for example. Note that the charge-generation layer113R2is indicated by the dashed line.

Next, the hydrophobization treatment for the conductive layer112G, for example, is preferably performed because it can increase the adhesion between the conductive layer112G and a layer to be formed in a later step (which is the EL layer113G here) and inhibit peeling, as described above. Note that the hydrophobization treatment is not necessarily performed.

Next, as illustrated inFIG.38C, an EL film113Gf to be the EL layer113G later is formed over the conductive layer112G, over the conductive layer112B, over the mask layer119R, and over the insulating layer105by a method similar to the method illustrated inFIG.25C. The EL film113Gf includes a film113G1fto be the light-emitting unit113G1later, a charge-generation film113G2fto be the charge-generation layer113G2later, and a film113G3fto be the light-emitting unit113G3later. InFIG.38C, the charge-generation film113Gf2is indicated by a dashed line.

Then, as illustrated inFIG.38C, the mask film118Gf to be the mask layer118G later and the mask film119Gf to be the mask layer119G later are sequentially formed over the EL film113Gf and over the mask layer119R by a method similar to the method illustrated inFIG.25C. After that, a resist mask190G is formed by a method similar to the method illustrated inFIG.25C.

Subsequently, as illustrated inFIG.38CandFIG.38D, part of the mask film119Gf is removed using the resist mask190G by a method similar to the method illustrated inFIG.25CandFIG.25D, whereby the mask layer119G is formed. After that, the resist mask190G is removed by a method similar to the method illustrated inFIG.25CandFIG.25D. Next, by a method similar to the method illustrated inFIG.25CandFIG.25D, part of the mask film118Gf is removed using the mask layer119G as a mask, whereby the mask layer118G is formed. Next, the EL film113Gf is processed to form the EL layer113G by a method similar to the method illustrated inFIG.25CandFIG.25D. The EL layer113G includes the light-emitting unit113G1, the charge-generation layer113G2over the light-emitting unit113G1, and the light-emitting unit113G3over the charge-generation layer113G2, for example. Note that the charge-generation layer113G2is indicated by the dashed line.

Next, as illustrated inFIG.39A, an EL film113Bf to be the EL layer113B later is formed over the conductive layer112B, over the mask layer119R, over the mask layer119G, and over the insulating layer105by a method similar to the method illustrated inFIG.26A. The EL film113Bf includes a film113B1fto be the light-emitting unit113B1later, a charge-generation film113B2fto be the charge-generation layer113B2later, and a film113B3fto be the light-emitting unit113B3later. InFIG.39A, the charge-generation film113Bf2is indicated by a dashed line.

Then, as illustrated inFIG.39A, the mask film118Bf to be the mask layer118B later and the mask film119Bf to be the mask layer119B later are sequentially formed over the EL film113Bf and over the mask layer119R by a method similar to the method illustrated inFIG.26A. After that, a resist mask190B is formed by a method similar to the method illustrated inFIG.26A.

Subsequently, as illustrated inFIG.39AandFIG.39B, part of the mask film119Bf is removed using the resist mask190B to form the mask layer119B by a method similar to the method illustrated inFIG.26AandFIG.26B. After that, the resist mask190B is removed by a method similar to the method illustrated inFIG.26AandFIG.26B. Next, by a method similar to the method illustrated inFIG.26AandFIG.26B, part of the mask film118Bf is removed using the mask layer119B as a mask, whereby the mask layer118B is formed. Next, the EL film113Bf is processed to form the EL layer113B by a method similar to the method illustrated inFIG.26AandFIG.26B. As described above, the EL layer113B includes the light-emitting unit113B1, the charge-generation layer113B2over the light-emitting unit113B1, and the light-emitting unit113B3over the charge-generation layer113B2, for example. Note that the charge-generation layer113B2is indicated by the dashed line.

FIG.39C,FIG.39D,FIG.40AtoFIG.40C,FIG.41A,FIG.41B,FIG.42A, andFIG.42Bshow steps similar to those inFIG.26C,FIG.26D,FIG.27A, FIG.27B1,FIG.28A,FIG.29A,FIG.30A,FIG.31A, andFIG.31B. After the step illustrated inFIG.42B, the substrate120is attached onto the protective layer131with the resin layer122, whereby the display device having the structure illustrated inFIG.14and the structure illustrated inFIG.18Ecan be manufactured.

Manufacturing Method Example 4

A manufacturing method example of the display device100having the structure illustrated inFIG.19Aand the structure illustrated inFIG.18Awill be described below with reference to drawings. Note that steps different from those in the method described withFIG.24AtoFIG.31Bwill be mainly described, and the description of the same steps as those in the method described withFIG.24AtoFIG.31Bwill be omitted as appropriate.

First, steps similar to the steps illustrated inFIG.24AandFIG.24Bare performed. Thus, the conductive layer111R, the conductive layer111G, the conductive layer111B, and the conductive layer111C are formed over the plugs106and over the insulating layer105, as illustrated inFIG.43A.

Next, as illustrated inFIG.43B, a conductive film112f1is formed over the conductive layer111R, over the conductive layer111G, over the conductive layer111B, over the conductive layer111C, and over the insulating layer105. The conductive film112f1can be formed by a method similar to the method for the conductive film112fillustrated inFIG.24C, for example, and formed using a material similar to that for the conductive film112f.

Then, as illustrated inFIG.43BandFIG.43C, the conductive film112f1is processed to form a conductive layer112B1that covers the upper surface and the side surface of the conductive layer111B. The conductive film112f1can be processed by a method similar to the method for processing the conductive film112f.

Next, as illustrated inFIG.43D, a conductive film112f2is formed over the conductive layer111R, over the conductive layer111G, over the conductive layer112B1, over the conductive layer111C, and over the insulating layer105. The conductive film112f2can be formed using a method and a material similar to those for the conductive film112f.

Subsequently, as illustrated inFIG.43DandFIG.43E, the conductive film112f2is processed, thereby forming the conductive layer112R1that covers the upper surface and the side surface of the conductive layer111R and a conductive layer112B2over the conductive layer112B1. InFIG.43E, the boundary between the conductive layer112B1and the conductive layer112B2is indicated by a dotted line.

Next, as illustrated inFIG.44A, a conductive film112f3is formed over the conductive layer112R1, over the conductive layer111G, over the conductive layer112B2, over the conductive layer111C, and over the insulating layer105. The conductive film112f3can be formed using a method and a material similar to those for the conductive film112f.

Then, as illustrated inFIG.44AandFIG.44B, the conductive film112f3is processed, thereby forming a conductive layer112R2over the conductive layer112R1, the conductive layer112G that covers the upper surface and the side surface of the conductive layer111G, a conductive layer112B3over the conductive layer112B2, and the conductive layer112C that covers the upper surface and the side surface of the conductive layer111C. The conductive layer112R, the conductive layer112R can form the conductive layer112R, and the conductive layer112B1, the conductive layer112B2, and the conductive layer112B3can form the conductive layer112B. The conductive film112f3can be processed by a method similar to the method for processing the conductive film112f. InFIG.44B, the boundary between the conductive layer112R1and the conductive layer112R2, the boundary between the conductive layer112B1and the conductive layer112B2, and the boundary between the conductive layer112B2and the conductive layer112B3are indicated by dotted lines. The same applies to the other diagrams.

In the above manner, the conductive layer112R, the conductive layer112G, and the conductive layer112B can have different thicknesses. Note that among the conductive layer112R, the conductive layer112G, and the conductive layer112B, the conductive layer112B has the largest thickness and the conductive layer112G has the smallest thickness: however, one embodiment of the present invention is not limited thereto, and the thicknesses of the conductive layer112R, the conductive layer112G, and the conductive layer112B can be set as appropriate. For example, among the conductive layer112R, the conductive layer112G, and the conductive layer112B, the conductive layer112R may have the largest thickness, and the conductive layer112B may have the smallest thickness.

Although the thickness of the conductive layer112C is equal to that of the conductive layer112G, one embodiment of the present invention is not limited thereto. For example, the thickness of the conductive layer112C may be larger than the thickness of the conductive layer112G. For example, not only at the time of processing the conductive film112f3but also at the time of processing the conductive film112f2, the conductive film may be left to cover the upper surface and the side surface of the conductive layer111C. In that case, the thickness of the conductive layer112C can be equal to the thickness of the conductive layer112R, for example. Furthermore, at the time of processing any of the conductive film112f1, the conductive film112f2, and the conductive film112f3, the conductive film may be left to cover the upper surface and the side surface of the conductive layer111C. In that case, the thickness of the conductive layer112C can be equal to the thickness of the conductive layer112B, for example.

Next, as illustrated inFIG.44C, an EL film113fto be the EL layer113later is formed over the conductive layer112R, over the conductive layer112G, over the conductive layer112B, and over the insulating layer105. Then, a mask film118fto be the mask layer118and a mask film119fto be a mask layer119are sequentially formed over the EL film113f, over the conductive layer112C, and over the insulating layer105.

Next, as illustrated inFIG.44C, the resist mask190is formed over the mask film119f. The resist mask190is provided at a position overlapping with the conductive layer112R, a position overlapping with the conductive layer112G, and a position overlapping with the conductive layer112B. The resist mask190is preferably provided also at a position overlapping with the conductive layer112C. Furthermore, the resist mask190is preferably provided to cover the area from the end portion of the EL film113fto the end portion of the conductive layer112C (the end portion closer to the EL film113f), as illustrated in the cross-sectional view along the line B1-B2 inFIG.44C.

Subsequently, as illustrated inFIG.44CandFIG.44D, part of the mask film119fis removed using the resist mask190, whereby the mask layer119is formed. The mask layer119remains over the conductive layer112R, over the conductive layer112G, over the conductive layer112B, and over the conductive layer112C. After that, the resist mask190is removed. Then, part of the mask film118fis removed using the mask layer119as a mask, whereby the mask layer118is formed.

Next, as illustrated inFIG.44CandFIG.44D, the EL film113fis processed, so that the EL layer113is formed. For example, part of the EL film113fis removed using the mask layer119and the mask layer118as a mask to form the EL layer113.

Thus, as illustrated inFIG.44D, the stacked-layer structure of the EL layer113, the mask layer118, and the mask layer119is left over the conductive layer112R, the conductive layer112G, and the conductive layer112B. In addition, in the cross section B1-B2, the mask layer118and the mask layer119can be provided to cover the area from the end portion of the EL layer113to the end portion of the conductive layer112C (the end portion closer to the EL layer113).

Subsequently, steps similar to the steps illustrated inFIG.26CtoFIG.31Bare performed. Subsequently, the coloring layer132R, the coloring layer132G, and the coloring layer132B are formed over the protective layer131. Subsequently, the substrate120is attached to the coloring layer132using the resin layer122, whereby the display device having the structure illustrated inFIG.19Aand the structure illustrated inFIG.18Acan be manufactured.

As described above, in the display device100having the structure illustrated inFIG.19A, the EL film113f, the mask film118f, and the mask film119fcan each be completed by one formation step and one processing step, and do not need to be formed and processed separately for each color. Thus, the manufacturing process of the display device100can be simplified. Consequently, the manufacturing cost of the display device100can be reduced, whereby the display device100can be an inexpensive display device.

Manufacturing Method Example 5

A manufacturing method example of the display device100having the structure illustrated inFIG.21Aand the structure illustrated inFIG.18Cwill be described below with reference to drawings. Note that a method different from the method described usingFIG.32AtoFIG.32CandFIG.33AtoFIG.37Bis mainly described, and the same method as the already-described method is omitted as appropriate

First, steps similar to those illustrated inFIG.32AtoFIG.32Care performed. Thus, as illustrated inFIG.45A, the conductive layer111R, the conductive layer111G, the conductive layer111B, and the conductive layer111C are formed over the plugs106and over the insulating layer105. The conductive film112fis formed over the conductive layer111R, over the conductive layer111G, over the conductive layer111B, over the conductive layer111C, and over the insulating layer105.

Next, as illustrated inFIG.45B, the EL film113fto be the EL layer113later is formed over the conductive film112f. Then, the mask film118fto be the mask layer118later and the mask film119fto be the mask layer119later are sequentially formed over the EL film113fand over the conductive film112f.

Next, as illustrated inFIG.45B, the resist mask190is formed over the mask film119f. The resist mask190is provided at a position overlapping with the conductive layer111R, a position overlapping with the conductive layer111G, and a position overlapping with the conductive layer111B. The resist mask190is preferably provided also at a position overlapping with the conductive layer111C. Furthermore, the resist mask190is preferably provided to cover the area from the end portion of the EL film113fto the end portion of the conductive layer111C (the end portion closer to the EL film113f), as illustrated in the cross-sectional view along the line B1-B2 inFIG.45B.

Subsequently, as illustrated inFIG.45BandFIG.45C, part of the mask film119fis removed using the resist mask190, whereby the mask layer119is formed. The mask layer119remains over the conductive layer111R, over the conductive layer111G, over the conductive layer111B, and over the conductive layer111C. After that, the resist mask190is removed. Then, part of the mask film118fis removed using the mask layer119as a mask, whereby the mask layer118is formed.

Next, as illustrated inFIG.45BandFIG.45C, the EL film113fis processed, so that the EL layer113is formed. For example, part of the EL film113fis removed using the mask layer119and the mask layer118as a mask to form the EL layer113.

Thus, as illustrated inFIG.45C, the stacked-layer structure of the EL layer113, the mask layer118, and the mask layer119is left over the conductive layer111R, the conductive layer111G, and the conductive layer111B. In addition, in the cross section B1-B2, the mask layer118and the mask layer119can be provided to cover the area from the end portion of the EL layer113to the end portion of the conductive layer111C (the end portion closer to the EL layer113).

Subsequently, steps similar to the steps illustrated inFIG.34CtoFIG.37Bare performed. Subsequently, the coloring layer132R, the coloring layer132G, and the coloring layer132B are formed over the protective layer131. Subsequently, the substrate120is attached to the coloring layer132using the resin layer122, whereby the display device having the structure illustrated inFIG.21Aand the structure illustrated inFIG.18Ccan be manufactured.

As described above, in the display device100having the structure illustrated inFIG.21A, the EL film113f, the mask film118f, and the mask film119fcan each be completed by one formation step and one processing step, and do not need to be formed and processed separately for each color. Thus, the manufacturing process of the display device100can be simplified. Consequently, the manufacturing cost of the display device100can be reduced, whereby the display device100can be an inexpensive display device.

This embodiment can be combined with the other embodiments as appropriate. In the case where a plurality of structure examples are described in one embodiment in this specification and the like, the structure examples can be combined as appropriate.

In this embodiment, a structure example of a light-emitting element that can be used for the display device of one embodiment of the present invention, specifically, a structure example of a light-emitting element having a tandem structure, will be described.

FIG.46Ais a schematic cross-sectional view of a display device500. The display device500includes a light-emitting element550R that emits red light, a light-emitting element550G that emits green light, and a light-emitting element550B that emits blue light.

The light-emitting element550R has a structure in which, between a pair of electrodes (an electrode501and an electrode502), two light-emitting units (a light-emitting unit512R_1and a light-emitting unit512R_2) are stacked with a charge-generation layer531therebetween. Similarly, the light-emitting element550G includes a light-emitting unit512G_1, the charge-generation layer531, and a light-emitting unit512G_2between the pair of electrodes, and the light-emitting element550B includes a light-emitting unit512B_1, the charge-generation layer531, and a light-emitting unit512B_2between the pair of electrodes.

The electrode501functions as a pixel electrode and is provided in every light-emitting element. The electrode502functions as a common electrode and is shared by a plurality of light-emitting elements.

As illustrated inFIG.46A, the light-emitting unit512R_1includes a layer521, a layer522, a light-emitting layer523R, and a layer524. The light-emitting unit512R_2includes the layer522, the light-emitting layer523R, and the layer524. The light-emitting element550R includes a layer525and the like between the light-emitting unit512R_2and the electrode502. Note that the layer525can also be regarded as part of the light-emitting unit512R_2.

In the case where the electrode501functions as an anode and the electrode502functions as a cathode, the layer521includes, for example, a layer containing a substance with a high hole-injection property (a hole-injection layer). The layer522includes one or both of a layer containing a substance with a high hole-transport property (a hole-transport layer) and a layer containing a substance with a high electron-blocking property (an electron-blocking layer), for example. The layer524includes one or both of a layer containing a substance with a high electron-transport property (an electron-transport layer) and a layer containing a substance with a high hole-blocking property (a hole-blocking layer), for example. The layer525includes, for example, a layer containing a substance with a high electron-injection property (an electron-injection layer).

In the case where the electrode501functions as a cathode and the electrode502functions as an anode, for example, the layer521includes an electron-injection layer, the layer522includes one or both of an electron-transport layer and a hole-blocking layer, the layer524includes one or both of a hole-transport layer and an electron-blocking layer, and the layer525includes a hole-injection layer.

Note that in terms of the layer522, the light-emitting layer523R, and the layer524, the light-emitting unit512R_1and the light-emitting unit512R_2may have the same structure (materials, thicknesses, and the like) or different structures.

FIG.46Aillustrates the layer521and the layer522separately: however, one embodiment of the present invention is not limited thereto. For example, the layer522may be omitted when the layer521has functions of both a hole-injection layer and a hole-transport layer or the layer521has functions of both an electron-injection layer and an electron-transport layer.

In the case of manufacturing a light-emitting element having a tandem structure, two light-emitting units are stacked with the charge-generation layer531therebetween. The charge-generation layer531includes at least a charge-generation region. The charge-generation layer531has a function of injecting electrons into one of the light-emitting unit512R_1and the light-emitting unit512R_2and injecting holes into the other when voltage is applied between the electrode501and the electrode502.

The light-emitting layer523R included in the light-emitting element550R contains a light-emitting substance that emits red light, the light-emitting layer523G included in the light-emitting element550G contains a light-emitting substance that emits green light, and the light-emitting layer523B included in the light-emitting element550B contains a light-emitting substance that emits blue light. Note that the light-emitting element550G and the light-emitting element550B have a structure in which the light-emitting layer523R included in the light-emitting element550R is replaced with the light-emitting layer523G and the light-emitting layer523B, respectively, and the other components are similar to those of the light-emitting element550R.

The structure (material, thickness, and the like) of the layer521, the layer522, the layer524, and the layer525may be the same among the light-emitting elements of two or more or all of the colors or different from each other among the light-emitting elements of all the colors.

A structure in which a plurality of light-emitting units are connected in series with the charge-generation layer531therebetween as in the light-emitting element550R, the light-emitting element550G, and the light-emitting element550B is referred to as a tandem structure in this specification. By contrast, a structure in which one light-emitting unit is provided between a pair of electrodes is referred to as a single structure. Note that the tandem structure may be referred to as a stack structure. The tandem structure enables a light-emitting element capable of high-luminance light emission. Furthermore, the tandem structure reduces the amount of current needed for obtaining the same luminance as compared with a single structure, and thus can improve the reliability of the light-emitting elements.

It can be said that the display device500according to one embodiment of the present invention employs a light-emitting element having a tandem structure and the display device has an SBS structure. Thus, the display device500can take advantages of both the tandem structure and the SBS structure. Note that the light-emitting element in the display device500illustrated inFIG.46Ahas a structure in which two light-emitting units are formed in series, and this structure may be referred to as a two-unit tandem structure. In the light-emitting element550R having a two-unit tandem structure illustrated inFIG.46A, a second light-emitting unit including a red-light-emitting layer is stacked over a first light-emitting unit including a red-light-emitting layer. Similarly, in the light-emitting element550G having a two-unit tandem structure illustrated inFIG.46A, a second light-emitting unit including a green-light-emitting layer is stacked over a first light-emitting unit including a green-light-emitting layer, and in the light-emitting element550B, a second light-emitting unit including a blue-light-emitting layer is stacked over a first light-emitting unit including a blue-light-emitting layer.

FIG.46Billustrates a modification example of the display device500illustrated inFIG.46A. The display device500illustrated inFIG.46Bis an example in which, like the electrode502, the layer525is shared by the plurality of light-emitting elements. In this case, the layer525can be referred to as a common layer. By providing one or more common layers for the plurality of light-emitting elements in this manner, the manufacturing step can be simplified, resulting in a reduction in manufacturing cost.

The display device500illustrated inFIG.47Ais an example in which three light-emitting units are stacked. In the light-emitting element550R inFIG.47A, a light-emitting unit512R_3is further stacked over the light-emitting unit512R_2with another charge-generation layer531therebetween. The light-emitting unit512R_3has a structure similar to that of the light-emitting unit512R_2. The same applies to a light-emitting unit512G_3included in the light-emitting element550G and a light-emitting unit512B_3included in the light-emitting element550B. Note that in the case where the light-emitting element includes a plurality of charge-generation layers531, two or more or all of the plurality of charge-generation layers531may have the same structure (material, thickness, and the like) or may have structures that are completely different from each other.

FIG.47Billustrates an example in which n light-emitting units (n is an integer greater than or equal to 2) are stacked.

When the number of stacked light-emitting units is increased in the above manner, luminance obtained from the light-emitting element with the same amount of current can be increased in accordance with the number of stacked layers. Moreover, increasing the number of stacked light-emitting units can reduce current necessary for obtaining the same luminance: thus, power consumption of the light-emitting element can be reduced in accordance with the number of stacked layers.

There is no particular limitation on the light-emitting substance in the light-emitting layer in the display device500illustrated in each ofFIG.46A,FIG.46B,FIG.47A, andFIG.47B. For example, the display device inFIG.46Acan have a structure in which the two light-emitting layers523R included in the light-emitting element550R each contain a phosphorescent material, the two light-emitting layers523G included in the light-emitting element550G each contain a fluorescent material, and the two light-emitting layers523B included in the light-emitting element550B each contain a fluorescent material.

Alternatively, for example, the display device inFIG.46Acan have a structure in which the two light-emitting layers523R included in the light-emitting element550R each contain a phosphorescent material, the two light-emitting layers523G included in the light-emitting element550G each contain a fluorescent material, and the two light-emitting layers523B included in the light-emitting element550B each contain a phosphorescent material.

For the display device of one embodiment of the present invention, a structure may be employed in which fluorescent materials are used for all the light-emitting layers included in the light-emitting element550R, the light-emitting element550G, and the light-emitting element550B or a structure may be employed in which phosphorescent materials are used for all the light-emitting layers included in the light-emitting element550R, the light-emitting element550G, and the light-emitting element550B.

InFIG.46A, for example, the structure may be employed in which the light-emitting layer523R included in the light-emitting unit512R_1contains a phosphorescent material and the light-emitting layer523R included in the light-emitting unit512R_2contains a fluorescent material, or a structure in which the light-emitting layer523R included in the light-emitting unit512R_1contains a fluorescent material and the light-emitting layer523R included in the light-emitting unit512R_2contains a phosphorescent material, i.e., a structure in which a light-emitting layer in a first unit and a light-emitting layer in a second unit are formed using different light-emitting substances. Note that here, the light-emitting unit512R_1and the light-emitting unit512R_2are described, and the same structure can also be applied to the light-emitting unit512G_1and the light-emitting unit512G_2, and the light-emitting unit512B_1and the light-emitting unit512B_2.

This embodiment can be combined with the other embodiments as appropriate. In the case where a plurality of structure examples are described in one embodiment in this specification, the structure examples can be combined as appropriate.

In this embodiment, display devices of embodiments of the present invention are described.

Pixel layouts different from the layout inFIG.1will be mainly described in this embodiment. There is no particular limitation on the arrangement of subpixels, and any of a variety of methods can be employed. Examples of the arrangement of subpixels include stripe arrangement, S-stripe arrangement, matrix arrangement, delta arrangement, Bayer arrangement, and PenTile arrangement.

The top surface shape of the subpixel illustrated in a diagram in this embodiment corresponds to the top surface shape of a light-emitting region.

Examples of the top surface shape of the subpixel include polygons such as a triangle, a tetragon (including a rectangle and a square), and a pentagon: polygons with rounded corners: an ellipse; and a circle.

The range of the circuit layout for forming the subpixels is not limited to the range of the subpixels illustrated in the drawing and may be placed outside the subpixels.

The pixel108illustrated inFIG.48Aemploys S-stripe arrangement. The pixel108illustrated inFIG.48Ais composed of three subpixels: the subpixel110R, the subpixel110G, and the subpixel110B.

The pixel108illustrated inFIG.48Bincludes the subpixel110R whose top surface has a rough trapezoidal shape with rounded corners, the subpixel110G whose top surface has a rough triangle shape with rounded corners, and the subpixel110B whose top surface has a rough tetragonal or rough hexagonal shape with rounded corners. The subpixel110R has a larger light-emitting area than the subpixel110G. In this manner, the shapes and sizes of the subpixels can be determined independently. For example, the size of a subpixel including a light-emitting element with higher reliability can be smaller.

A pixel124aand a pixel124billustrated inFIG.48Cemploy PenTile arrangement.FIG.48Cillustrates an example where the pixels124aincluding the subpixel110R and the subpixel110G and the pixels124bincluding the subpixel110G and the subpixel110B are alternately arranged.

The pixel124aand the pixel124billustrated inFIG.48DtoFIG.48Femploy delta arrangement. The pixel124aincludes two subpixels (the subpixel110R and the subpixel110G) in the upper row (first row) and one subpixel (the subpixel110B) in the lower row (second row). The pixel124bincludes one subpixel (the subpixel110B) in the upper row (first row) and two subpixels (the subpixel110R and the subpixel110G) in the lower row (second row).

FIG.48Dillustrates an example where the upper surface of each subpixel has a rough tetragonal shape with rounded corners,FIG.48Eillustrates an example where the upper surface of each subpixel is circular, andFIG.48Fillustrates an example where the upper surface of each subpixel has a rough hexagonal shape with rounded corners.

InFIG.48F, each subpixel is placed inside one of close-packed hexagonal regions. Focusing on one of the subpixels, the subpixel is placed so as to be surrounded by six subpixels. The subpixels are arranged such that subpixels that emit light of the same color are not adjacent to each other. For example, focusing on the subpixel110R, the subpixel110R is surrounded by three subpixels110G and three subpixels110B that are alternately arranged.

FIG.48Gillustrates an example where subpixels of different colors are arranged in a zigzag manner. Specifically, the positions of the top sides of two subpixels arranged in the column direction (e.g., the subpixel110R and the subpixel110G or the subpixel110G and the subpixel110B) are not aligned in the plan view.

For example, in each pixel illustrated inFIG.48AtoFIG.48G, it is preferable that the subpixel110R be a subpixel R emitting red light, the subpixel110G be a subpixel G emitting green light, and the subpixel110B be a subpixel B emitting blue light. Note that the structure of the subpixels is not limited to this, and the colors and arrangement order of the subpixels can be determined as appropriate. For example, the subpixel110G may be the subpixel R emitting red light and the subpixel110R may be the subpixel G emitting green light.

In a photolithography method, as a pattern to be processed becomes finer, the influence of light diffraction becomes more difficult to ignore: therefore, the fidelity in transferring a photomask pattern by light exposure is degraded, and it becomes difficult to process a resist mask into a desired shape. Thus, a pattern with rounded corners is likely to be formed even with a rectangular photomask pattern. Consequently, the top surface of a subpixel may have a polygonal shape with rounded corners, an elliptical shape, a circular shape, or the like.

Furthermore, in the method of manufacturing the display device of one embodiment of the present invention, the EL layer is processed into an island shape using a resist mask. A resist film formed over the EL layer needs to be cured at a temperature lower than the upper temperature limit of the EL layer. Therefore, the resist film is insufficiently cured in some cases depending on the upper temperature limit of the material of the EL layer and the curing temperature of the resist material. An insufficiently cured resist film may have a shape different from a desired shape after being processed. As a result, the top surface of the EL layer may have a polygonal shape with rounded corners, an elliptical shape, a circular shape, or the like. For example, when a resist mask whose top surface has a square shape is intended to be formed, a resist mask whose top surface has a circular shape may be formed, and the top surface of the EL layer may have a circular shape.

Note that to obtain a desired top surface shape of the EL layer, a technique of correcting a mask pattern in advance so that a transferred pattern agrees with a design pattern (OPC (Optical Proximity Correction) technique) may be used. Specifically, with the OPC technique, a pattern for correction is added to a corner portion or the like of a figure on a mask pattern.

As illustrated inFIG.49AtoFIG.49I, the pixel can include four types of subpixels.

FIG.49Aillustrates an example where each subpixel has a rectangular top surface shape,FIG.49Billustrates an example where each subpixel has a top surface shape formed by combining two half circles and a rectangle, andFIG.49Cillustrates an example where each subpixel has an elliptical top surface shape.

FIG.49Dillustrates an example where each subpixel has a square top surface shape,FIG.49Eillustrates an example where each subpixel has a rough square top surface shape with rounded corners, andFIG.49Fillustrates an example where each subpixel has a circular top surface shape.

FIG.49GandFIG.49Heach illustrate an example where one pixel108is composed of two rows and three columns.

The pixel108illustrated inFIG.49Gincludes three subpixels (the subpixel110R, the subpixel110G, and the subpixel110B) in the upper row (first row) and one subpixel (the subpixel110W) in the lower row (second row). In other words, the pixel108includes the subpixel110R in the left column (first column), the subpixel110G in the center column (second column), the subpixel110B in the right column (third column), and the subpixel110W across these three columns.

The pixel108illustrated inFIG.49Hincludes three subpixels (the subpixel110R, the subpixel110G, and the subpixel110B) in the upper row (first row) and three of the subpixels110W in the lower row (second row). In other words, the pixel108includes the subpixel110R and the subpixel110W in the left column (first column), the subpixel110G and another subpixel110W in the center column (second column), and the subpixel110B and another subpixel110W in the right column (third column). Matching the positions of the subpixels in the upper row and the lower row as illustrated inFIG.49Henables efficient removal of dust that would be produced in the manufacturing process, for example. Thus, a display device with high display quality can be provided.

In the pixel108illustrated inFIG.49GandFIG.49H, stripe arrangement is employed as the layout of the subpixel110R, the subpixel110G, and the subpixel110B, whereby the display quality can be improved.

FIG.49Iillustrates an example where one pixel108is composed of three rows and two columns.

The pixel108illustrated inFIG.49Iincludes the subpixel110R in the upper row (first row), the subpixel110G in the center row (second row), the subpixel110B across the first and second rows, and one subpixel (the subpixel110W) in the lower row (third row). In other words, the pixel108includes the subpixel110R and the subpixel110G in the left column (first column), the subpixel110B in the right column (second column), and the subpixel110W across these two columns.

In the pixel108illustrated inFIG.49I, so-called S stripe arrangement is employed as the layout of the subpixel110R, the subpixel110G, and the subpixel110B, whereby the display quality can be improved.

The pixel108illustrated inFIG.49AtoFIG.49Iconsists of four subpixels: the subpixel110R, the subpixel110G, the subpixel110B, and the subpixel110W. For example, the subpixel110R can be a subpixel that emits red light, the subpixel110G can be a subpixel that emits green light, the subpixel110B can be a subpixel that emits blue light, and the subpixel110W can be a subpixel that emits white light. Note that at least one of the subpixel110R, the subpixel110G, the subpixel110B, and the subpixel110W may be a subpixel that emits cyan light, a subpixel that emits magenta light, a subpixel that emits yellow light, or a subpixel that emits near-infrared light.

As described above, the pixel composed of the subpixels each including the light-emitting element can employ any of a variety of layouts in the display device of one embodiment of the present invention.

This embodiment can be combined with the other embodiments as appropriate. In the case where a plurality of structure examples are described in one embodiment in this specification, the structure examples can be combined as appropriate.

In this embodiment, display devices of embodiments of the present invention are described.

The display device of this embodiment can be a high-resolution display device. Accordingly, the display device in this embodiment can be used for display portions of information terminals (wearable devices) such as watch-type and bracelet-type information terminals and display portions of wearable devices capable of being worn on a head, such as a VR device like a head-mounted display (HMD) and a glasses-type AR device.

The display device of this embodiment can be a high-definition display device or a large-sized display device. Accordingly, the display device of this embodiment can be used for display portions of electronic devices such as a digital camera, a digital video camera, a digital photo frame, a mobile phone, a portable game console, a portable information terminal, and an audio reproducing device, in addition to display portions of electronic devices with a relatively large screen, such as a television device, a desktop or notebook personal computer, a monitor of a computer and the like, digital signage, and a large game machine such as a pachinko machine.

FIG.50Ais a perspective view of a display module280. The display module280includes a display device100A and an FPC290. Note that the display device included in the display module280is not limited to the display device100A and may be any of a display device100B to a display device100F described later.

FIG.50Bis a perspective view schematically illustrating a structure on the substrate291side. Over the substrate291, a circuit portion282, a pixel circuit portion283over the circuit portion282, and the pixel portion284over the pixel circuit portion283are stacked. A terminal portion285to be connected to the FPC290is provided in a portion over the substrate291that does not overlap with the pixel portion284. The terminal portion285and the circuit portion282are electrically connected to each other through a wiring portion286formed of a plurality of wirings.

The pixel portion284includes a plurality of pixels284aarranged periodically. An enlarged view of one pixel284ais illustrated on the right side ofFIG.50B. The pixel284acan employ any of the structures described in the above embodiments.FIG.50Billustrates an example where the pixel284ahas a structure similar to that of the pixel108illustrated inFIG.1.

The pixel circuit portion283includes a plurality of pixel circuits283aarranged periodically.

One pixel circuit283ais a circuit that controls driving of a plurality of elements included in one pixel284a. One pixel circuit283acan be provided with three circuits each controlling light emission of one light-emitting element. For example, the pixel circuit283acan include at least one selection transistor, one current control transistor (driving transistor), and a capacitor for one light-emitting element. In this case, a gate signal is input to a gate of the selection transistor, and a source signal is input to a source or a drain of the selection transistor. Thus, an active-matrix display device is achieved.

The circuit portion282includes a circuit for driving the pixel circuits283ain the pixel circuit portion283. For example, one or both of a gate line driver circuit and a source line driver circuit are preferably included. In addition, at least one of an arithmetic circuit, a memory circuit, a power supply circuit, and the like may be included.

The FPC290functions as a wiring for supplying a video signal, a power supply potential, or the like to the circuit portion282from the outside. An integrated circuit (IC) may be mounted on the FPC290.

The display module280can have a structure in which one or both of the pixel circuit portion283and the circuit portion282are stacked below the pixel portion284: thus, the aperture ratio (the effective display area ratio) of the display portion281can be significantly high. For example, the aperture ratio of the display portion281can be higher than or equal to 40% and lower than 100%, preferably higher than or equal to 50% and lower than or equal to 95%, further preferably higher than or equal to 60% and lower than or equal to 95%. Furthermore, the pixels284acan be arranged extremely densely and thus, the display portion281can have an extremely high resolution. For example, the pixels284aare preferably arranged in the display portion281with a resolution higher than or equal to 2000 ppi, preferably higher than or equal to 3000 ppi, further preferably higher than or equal to 5000 ppi, still further preferably higher than or equal to 6000 ppi, and lower than or equal to 20000 ppi or lower than or equal to 30000 ppi.

Such a display module280has an extremely high resolution, and thus can be suitably used for a VR device such as an HMD or a glasses-type AR device. For example, even with a structure where the display portion of the display module280is seen through a lens, pixels of the extremely-high-resolution display portion281included in the display module280are prevented from being seen when the display portion is enlarged by the lens, so that display providing a high sense of immersion can be performed. Without being limited thereto, the display module280can be suitably used for electronic devices including a relatively small display portion. For example, the display module280can be favorably used in a display portion of a wearable electronic device, such as a watch.

The display device100A illustrated inFIG.51Aincludes a substrate301, a light-emitting element130R, a light-emitting element130G, a light-emitting element130B, a capacitor240, and a transistor310.

The substrate301corresponds to the substrate291inFIG.50AandFIG.50B. The transistor310is a transistor including a channel formation region in the substrate301. As the substrate301, a semiconductor substrate such as a single crystal silicon substrate can be used, for example. The transistor310includes part of the substrate301, a conductive layer311, low-resistance regions312, an insulating layer313, and an insulating layer314. The conductive layer311functions as a gate electrode. The insulating layer313is positioned between the substrate301and the conductive layer311and functions as a gate insulating layer. The low-resistance region312is a region where the substrate301is doped with an impurity, and functions as one of a source and a drain. The insulating layer314is provided to cover the side surface of the conductive layer311.

An element isolation layer315is provided between two adjacent transistors310to be embedded in the substrate301.

An insulating layer261is provided to cover the transistor310, and the capacitor240is provided over the insulating layer261.

The capacitor240includes a conductive layer241, a conductive layer245, and an insulating layer243positioned therebetween. The conductive layer241functions as one electrode of the capacitor240, the conductive layer245functions as the other electrode of the capacitor240, and the insulating layer243functions as a dielectric of the capacitor240.

The conductive layer241is provided over the insulating layer261and is embedded in an insulating layer254. The conductive layer241is electrically connected to one of the source and the drain of the transistor310through a plug271embedded in the insulating layer261. The insulating layer243is provided to cover the conductive layer241. The conductive layer245is provided in a region overlapping with the conductive layer241with the insulating layer243therebetween.

An insulating layer255is provided to cover the capacitor240, the insulating layer104is provided over the insulating layer255, and the insulating layer105is provided over the insulating layer104. The light-emitting element130R, the light-emitting element130G, and the light-emitting element130B are provided over the insulating layer105.FIG.51Aillustrates an example where the light-emitting element130R, the light-emitting element130G, and the light-emitting element130B have a structure similar to the stacked-layer structure illustrated inFIG.2A. An insulator is provided in a region between adjacent light-emitting elements. InFIG.51A, for example, the insulating layer125and the insulating layer127over the insulating layer125are provided in this region.

The mask layer118R is positioned over the EL layer113R included in the light-emitting element130R, the mask layer118G is positioned over the EL layer113G included in the light-emitting element130G, and the mask layer118B is positioned over the EL layer113B included in the light-emitting element130B.

A conductive layer111R, a conductive layer111G, and a conductive layer111B are each electrically connected to one of the source and the drain of the transistor310through a plug256embedded in the insulating layer243, the insulating layer255, the insulating layer104, and the insulating layer105, the conductive layer241embedded in the insulating layer254, and the plug271embedded in the insulating layer261. The level of the upper surface of the insulating layer105is equal to or substantially equal to the level of the upper surface of the plug256. A variety of conductive materials can be used for the plugs.

The protective layer131is provided over the light-emitting element130R, the light-emitting element130G, and the light-emitting element130B. The substrate120is attached to the protective layer131with the resin layer122. Embodiment 1 can be referred to for details of the light-emitting elements130and the components thereover up to the substrate120. The substrate120corresponds to the substrate292inFIG.50A.

FIG.51Billustrates a modification example of the display device100A illustrated inFIG.51A. The display device illustrated inFIG.51Bincludes the coloring layer132R, the coloring layer132G, and the coloring layer132B, and each of the light-emitting elements130includes a region overlapping with one of the coloring layer132R, the coloring layer132G, and the coloring layer132B.FIG.19Acan be referred to for the details of the light-emitting element130and the components thereover up to the substrate120in the display device illustrated inFIG.51B. In the display device illustrated inFIG.51B, the light-emitting element130can emit white light, for example. For example, the coloring layer132R can transmit red light, the coloring layer132G can transmit green light, and the coloring layer132B can transmit blue light.

FIG.52Aillustrates a modification example of the structure illustrated inFIG.51A, and in the example, the light-emitting element130R, the light-emitting element130G, and the light-emitting element130B have the structure illustrated inFIG.10.FIG.52Billustrates a modification example of the structure illustrated inFIG.51B, and in the example, the light-emitting element130R, the light-emitting element130G, and the light-emitting element130B have the structure illustrated inFIG.21A.FIG.53illustrates a modification example of the structure illustrated inFIG.51A, and in the example, the light-emitting element130R, the light-emitting element130G, and the light-emitting element130B have the structure illustrated inFIG.14.

The display device100B illustrated inFIG.54has a structure where a transistor310A and a transistor310B in each of which a channel is formed in a semiconductor substrate are stacked. Note that in the description of the display device below, portions similar to those of the above-mentioned display device are not described in some cases.

In the display device100B, a substrate301B provided with the transistor310B, the capacitor240, and the light-emitting elements is bonded to a substrate301A provided with the transistor310A.

Here, an insulating layer345is preferably provided on the lower surface of the substrate301B. An insulating layer346is preferably provided over the insulating layer261provided over the substrate301A. The insulating layer345and the insulating layer346are insulating layers functioning as protective layers and can inhibit diffusion of impurities into the substrate301B and the substrate301A. For the insulating layer345and the insulating layer346, an inorganic insulating film that can be used for the protective layer131can be used.

The substrate301B is provided with a plug343that penetrates the substrate301B and the insulating layer345. Here, an insulating layer344is preferably provided to cover the side surface of the plug343. The insulating layer344functions as a protective layer and can inhibit diffusion of impurities into the substrate301B. For the insulating layer344, an inorganic insulating film that can be used for the protective layer131can be used.

A conductive layer342is provided under the insulating layer345on the rear surface of the substrate301B (the surface of the substrate301A). The conductive layer342is preferably provided to be embedded in an insulating layer335. The bottom surfaces of the conductive layer342and the insulating layer335are preferably planarized. Here, the conductive layer342is electrically connected to the plug343.

Between the substrate301A and the substrate301B, a conductive layer341is provided over the insulating layer346. The conductive layer341is preferably provided to be embedded in an insulating layer336. The upper surfaces of the conductive layer341and the insulating layer336are preferably planarized.

The conductive layer341and the conductive layer342are bonded to each other, whereby the substrate301A and the substrate301B are electrically connected to each other. Here, improving the planarity of a plane formed by the conductive layer342and the insulating layer335and a plane formed by the conductive layer341and the insulating layer336allows the conductive layer341and the conductive layer342to be bonded to each other favorably.

The conductive layer341and the conductive layer342are preferably formed using the same conductive material. For example, a metal film containing an element selected from Al, Cr, Cu, Ta, Ti, Mo, and W, a metal nitride film containing the above element as a component (a titanium nitride film, a molybdenum nitride film, or a tungsten nitride film), or the like can be used. Copper is particularly preferably used for the conductive layer341and the conductive layer342. In that case, it is possible to employ Cu-to-Cu (copper-to-copper) direct bonding technique (a technique for achieving electrical continuity by connecting Cu (copper) pads).

FIG.55illustrates a modification example of the structure illustrated inFIG.54, and in the example, the light-emitting element130R, the light-emitting element130G, and the light-emitting element130B have the structure illustrated inFIG.10.FIG.56illustrates a modification example of the structure illustrated inFIG.54, and in the example, the light-emitting element130R, the light-emitting element130G, and the light-emitting element130B have the structure illustrated inFIG.14.

The display device100C illustrated inFIG.57has a structure where the conductive layer341and the conductive layer342are bonded to each other through a bump347.

As illustrated inFIG.57, providing the bump347between the conductive layer341and the conductive layer342enables the conductive layer341and the conductive layer342to be electrically connected to each other. The bump347can be formed using a conductive material containing gold (Au), nickel (Ni), indium (In), tin (Sn), or the like, for example. For another example, solder may be used for the bump347. An adhesive layer348may be provided between the insulating layer345and the insulating layer346. In the case where the bump347is provided, the insulating layer335and the insulating layer336may be omitted.

FIG.58illustrates a modification example of the structure illustrated inFIG.57, and in the example, the light-emitting element130R, the light-emitting element130G, and the light-emitting element130B have the structure illustrated inFIG.10.FIG.59illustrates a modification example of the structure illustrated inFIG.57, and in the example, the light-emitting element130R, the light-emitting element130G, and the light-emitting element130B have the structure illustrated inFIG.14.

The display device100D illustrated inFIG.60differs from the display device100A mainly in a structure of a transistor.

A transistor320is a transistor that contains a metal oxide (also referred to as an oxide semiconductor) in a semiconductor layer where a channel is formed (hereinafter, the transistor is referred to as OS transistor).

The transistor320includes a semiconductor layer321, an insulating layer323, a conductive layer324, a pair of conductive layers325, an insulating layer326, and a conductive layer327.

A substrate331corresponds to the substrate291inFIG.50AandFIG.50B. As the substrate331, an insulating substrate or a semiconductor substrate can be used.

The insulating layer332is provided over the substrate331. The insulating layer332functions as a barrier layer that inhibits diffusion of impurities such as water and hydrogen from the substrate331into the transistor320and release of oxygen from the semiconductor layer321to the insulating layer332side. As the insulating layer332, for example, a film in which hydrogen or oxygen is less likely to diffuse than in a silicon oxide film, such as an aluminum oxide film, a hafnium oxide film, or a silicon nitride film, can be used.

The conductive layer327is provided over the insulating layer332, and the insulating layer326is provided to cover the conductive layer327. The conductive layer327functions as a first gate electrode of the transistor320, and part of the insulating layer326functions as a first gate insulating layer. An oxide insulating film such as a silicon oxide film is preferably used as at least part of the insulating layer326that is in contact with the semiconductor layer321. The upper surface of the insulating layer326is preferably planarized.

The semiconductor layer321is provided over the insulating layer326. The semiconductor layer321preferably includes a metal oxide film having semiconductor characteristics. The pair of conductive layers325are provided over and in contact with the semiconductor layer321and function as a source electrode and a drain electrode.

An insulating layer328is provided to cover the upper surfaces and the side surfaces of the pair of conductive layers325, the side surface of the semiconductor layer321, and the like, and an insulating layer264is provided over the insulating layer328. The insulating layer328functions as a barrier layer that inhibits diffusion of impurities such as water and hydrogen from, for example, the insulating layer264into the semiconductor layer321and release of oxygen from the semiconductor layer321. As the insulating layer328, an insulating film similar to the insulating layer332can be used.

An opening reaching the semiconductor layer321is provided in the insulating layer328and the insulating layer264. The insulating layer323that is in contact with the side surfaces of the insulating layer264, the insulating layer328, and the conductive layer325, and the top surface of the semiconductor layer321, and the conductive layer324are embedded in the opening. The conductive layer324functions as a second gate electrode, and the insulating layer323functions as a second gate insulating layer.

The upper surface of the conductive layer324, the upper surface of the insulating layer323, and the upper surface of the insulating layer264are subjected to planarization treatment so that their levels are equal to or substantially equal to each other, and an insulating layer329and an insulating layer265are provided to cover these layers.

The insulating layer264and the insulating layer265each function as an interlayer insulating layer. The insulating layer329functions as a barrier layer that inhibits diffusion of impurities such as water and hydrogen from the insulating layer265into the transistor320, for example. As the insulating layer329, an insulating film similar to the insulating layer328and the insulating layer332can be used.

A plug274electrically connected to one of the pair of conductive layers325is provided so as to be embedded in the insulating layer265, the insulating layer329, the insulating layer264, and the insulating layer328. Here, the plug274preferably includes a conductive layer274athat covers the side surface of an opening in the insulating layer265, the insulating layer329, the insulating layer264, and the insulating layer328and part of upper surface of the conductive layer325, and a conductive layer274bin contact with the upper surface of the conductive layer274a. In that case, a conductive material in which hydrogen and oxygen are less likely to diffuse is preferably used for the conductive layer274a.

FIG.61illustrates a modification example of the structure illustrated inFIG.60, and in the example, the light-emitting element130R, the light-emitting element130G, and the light-emitting element130B have the structure illustrated inFIG.10.FIG.62illustrates a modification example of the structure illustrated inFIG.60, and in the example, the light-emitting element130R, the light-emitting element130G, and the light-emitting element130B have the structure illustrated inFIG.14.

The display device100E illustrated inFIG.63has a structure in which a transistor320A and a transistor320B each including an oxide semiconductor in a semiconductor where a channel is formed are stacked.

The description of the display device100D can be referred to for the transistor320A, the transistor320B, and the components around them.

Although the structure where two transistors including an oxide semiconductor are stacked is described here, the present invention is not limited thereto. For example, three or more transistors may be stacked.

FIG.64illustrates a modification example of the structure illustrated inFIG.63, and in the example, the light-emitting element130R, the light-emitting element130G, and the light-emitting element130B have the structure illustrated inFIG.10.FIG.65illustrates a modification example of the structure illustrated inFIG.63, and in the example, the light-emitting element130R, the light-emitting element130G, and the light-emitting element130B have the structure illustrated inFIG.14.

The display device100F illustrated inFIG.66has a structure in which the transistor310whose channel is formed in the substrate301and the transistor320including a metal oxide in the semiconductor layer where the channel is formed are stacked.

The insulating layer261is provided to cover the transistor310, and a conductive layer251is provided over the insulating layer261. An insulating layer262is provided to cover the conductive layer251, and a conductive layer252is provided over the insulating layer262. The conductive layer251and the conductive layer252each function as a wiring. An insulating layer263and the insulating layer332are provided to cover the conductive layer252, and the transistor320is provided over the insulating layer332. The insulating layer265is provided to cover the transistor320, and the capacitor240is provided over the insulating layer265. The capacitor240and the transistor320are electrically connected to each other through the plug274.

The transistor320can be used as a transistor included in the pixel circuit. The transistor310can be used as a transistor included in the pixel circuit or a transistor included in a driver circuit (a gate line driver circuit or a source line driver circuit) for driving the pixel circuit. The transistor310and the transistor320can also be used as transistors included in a variety of circuits such as an arithmetic circuit and a memory circuit.

With such a structure, not only the pixel circuit but also the driver circuit, for example, can be formed directly under the light-emitting elements; thus, the display device can be downsized as compared with the case where a driver circuit is provided around a display region.

FIG.67illustrates a modification example of the structure illustrated inFIG.66, and in the example, the light-emitting element130R, the light-emitting element130G, and the light-emitting element130B have the structure illustrated inFIG.10.FIG.68illustrates a modification example of the structure illustrated inFIG.66, and in the example, the light-emitting element130R, the light-emitting element130G, and the light-emitting element130B have the structure illustrated inFIG.14.

FIG.69is a perspective view of a display device100G, andFIG.70Ais a cross-sectional view of the display device100G.

In the display device100G, a substrate152and a substrate151are bonded to each other. InFIG.69, the substrate152is clearly denoted by a dashed line.

The display device100G includes the pixel portion107, the connection portion140, a circuit164, a wiring165, and the like.FIG.69illustrates an example where an IC173and an FPC172are mounted on the display device100G. Thus, the structure illustrated inFIG.69can be regarded as a display module including the display device100G, the IC, and the FPC. Here, a display device in which a substrate is equipped with a connector such as an FPC or mounted with an IC is referred to as a display module.

The connection portion140is provided outside the pixel portion107. The connection portion140can be provided along one or more sides of the pixel portion107. The number of connection portions140can be one or more.FIG.69illustrates an example where the connection portion140is provided to surround the four sides of the display portion. A common electrode of a light-emitting element is electrically connected to a conductive layer in the connection portion140, so that a potential can be supplied to the common electrode.

As the circuit164, a scan line driver circuit can be used, for example.

The wiring165has a function of supplying a signal and power to the pixel portion107and the circuit164. The signal and power are input to the wiring165from the outside through the FPC172or from the IC173.

FIG.69illustrates an example where the IC173is provided over the substrate151by a COG (Chip On Glass) method, a COF (Chip On Film) method, or the like. An IC including a scan line driver circuit, a signal line driver circuit, or the like can be used as the IC173, for example. Note that the display device100G and the display module are not necessarily provided with an IC. The IC may be mounted on the FPC by a COF method, for example.

FIG.70Aillustrates example cross sections of part of a region including the FPC172, part of the circuit164, part of the pixel portion107, part of the connection portion140, and part of a region including an end portion of the display device100G.

The display device100G illustrated inFIG.70Aincludes a transistor201, a transistor205, the light-emitting element130R that emits red light, the light-emitting element130G that emits green light, the light-emitting element130B that emits blue light, and the like between the substrate151and the substrate152.

The light-emitting element130R, the light-emitting element130G, and the light-emitting element130B each have the same structure as the stacked-layer structure illustrated inFIG.2Aexcept the structure of the pixel electrode. For details of the light-emitting element, Embodiment 1 can be referred to.

The light-emitting element130R includes a conductive layer224R, the conductive layer111R over the conductive layer224R, and the conductive layer112R over the conductive layer111R. All of the conductive layer224R, the conductive layer111R, and the conductive layer112R can be referred to as a pixel electrode, or the conductive layer111R and the conductive layer112R can be referred to as a pixel electrode.

The light-emitting element130G includes a conductive layer224G, the conductive layer111G over the conductive layer224G, and the conductive layer112G over the conductive layer111G.

The light-emitting element130B includes a conductive layer224B, the conductive layer111B over the conductive layer224B, and the conductive layer112B over the conductive layer111B.

The conductive layer224R is connected to a conductive layer222bincluded in the transistor205through an opening provided in an insulating layer214, an insulating layer215, and an insulating layer213. An end portion of the conductive layer111R is positioned on the outer side of an end portion of the conductive layer224R. As described above, the conductive layer112R is provided to cover the upper surface and the side surface of the conductive layer111R.

Detailed description of the conductive layer224G, the conductive layer111G, and the conductive layer112G of the light-emitting element130G and the conductive layer224B, the conductive layer111B, and the conductive layer112B of the light-emitting element130B is omitted because these conductive layers are similar to the conductive layer224R, the conductive layer111R, and the conductive layer112R of the light-emitting element130R.

The conductive layer224R, the conductive layer224G, and the conductive layer224B are formed to cover the openings provided in the insulating layer214. A layer128is embedded in each of the depressed portions.

The layer128has a planarization function for the depressed portions of the conductive layer224R, the conductive layer224G, and the conductive layer224B. Over the conductive layer224R, the conductive layer224G, the conductive layer224B, and the layer128, the conductive layer111R, the conductive layer111G, and the conductive layer111B that are respectively electrically connected to the conductive layer224R, the conductive layer224G, and the conductive layer224B are provided. Thus, regions overlapping with the depressed portions of the conductive layer224R, the conductive layer224G, and the conductive layer224B can also be used as the light-emitting regions, increasing the aperture ratio of the pixels.

The layer128may be an insulating layer or a conductive layer. Any of a variety of inorganic insulating materials, organic insulating materials, and conductive materials can be used for the layer128as appropriate. Specifically, the layer128is preferably formed using an insulating material and is further preferably formed using an organic insulating material. For the layer128, an organic insulating material that can be used for the insulating layer127can be used, for example.

The protective layer131is provided over the light-emitting element130R, the light-emitting element130G, and the light-emitting element130B. The protective layer131and the substrate152are bonded to each other with an adhesive layer142. The substrate152is provided with a light-blocking layer117. A solid sealing structure, a hollow sealing structure, or the like can be employed to seal the light-emitting elements130. InFIG.70A, a solid sealing structure is employed in which a space between the substrate152and the substrate151is filled with the adhesive layer142. Alternatively, a hollow sealing structure in which the space is filled with an inert gas (e.g., nitrogen or argon) may be employed. Here, the adhesive layer142may be provided not to overlap with the light-emitting elements. The space may be filled with a resin different from that of the frame-shaped adhesive layer142.

FIG.70Aillustrates an example in which the connection portion140includes a conductive layer224C obtained by processing the same conductive film as the conductive layer224R, the conductive layer224G, and the conductive layer224B, the conductive layer111C obtained by processing the same conductive film as the conductive layer111R, the conductive layer111G, and the conductive layer111B, and the conductive layer112C obtained by processing the same conductive film as the conductive layer112R, the conductive layer112G, and the conductive layer112B.

The display device100G has a top-emission structure. Light emitted by the light-emitting element is emitted toward the substrate152side. For the substrate152, a material having a high visible-light-transmitting property is preferably used. The pixel electrode contains a material that reflects visible light, and a counter electrode (the common electrode115) contains a material that transmits visible light.

The transistor201and the transistor205are formed over the substrate151. These transistors can be fabricated using the same material in the same process.

An insulating layer211, an insulating layer213, an insulating layer215, and the insulating layer214are provided in this order over the substrate151. Part of the insulating layer211functions as a gate insulating layer of each transistor. Part of the insulating layer213functions as a gate insulating layer of each transistor. The insulating layer215is provided to cover the transistors. The insulating layer214is provided to cover the transistors and has a function of a planarization layer. Note that the number of gate insulating layers and the number of insulating layers covering the transistors are not limited and may each be one or two or more.

A material in which impurities such as water and hydrogen do not easily diffuse is preferably used for at least one of the insulating layers covering the transistors. In that case, the insulating layer can function as a barrier layer. Such a structure can effectively inhibit diffusion of impurities into the transistors from the outside and increase the reliability of the display device.

An inorganic insulating film is preferably used as each of the insulating layer211, the insulating layer213, and the insulating layer215. As the inorganic insulating film, a silicon nitride film, a silicon oxynitride film, a silicon oxide film, a silicon nitride oxide film, an aluminum oxide film, or an aluminum nitride film can be used, for example. A hafnium oxide film, an yttrium oxide film, a zirconium oxide film, a gallium oxide film, a tantalum oxide film, a magnesium oxide film, a lanthanum oxide film, a cerium oxide film, a neodymium oxide film, or the like may be used. A stack including two or more of the above insulating films may also be used.

An organic insulating layer is suitable as the insulating layer214functioning as a planarization layer. Examples of materials that can be used for the organic insulating layer include an acrylic resin, a polyimide resin, an epoxy resin, a polyamide resin, a polyimide-amide resin, a siloxane resin, a benzocyclobutene-based resin, a phenol resin, and precursors of these resins. The insulating layer214may have a stacked-layer structure of an organic insulating layer and an inorganic insulating layer. The uppermost layer of the insulating layer214preferably has a function of an etching protective layer. In that case, a depressed portion can be inhibited from being formed in the insulating layer214at the time of processing the conductive layer224R, the conductive layer111R, the conductive layer112R, or the like. Alternatively, a depressed portion may be formed in the insulating layer214at the time of processing the conductive layer224R, the conductive layer111R, the conductive layer112R, or the like.

Each of the transistor201and the transistor205includes a conductive layer221functioning as a gate, the insulating layer211functioning as a gate insulating layer, a conductive layer222aand the conductive layer222bfunctioning as a source and a drain, a semiconductor layer231, the insulating layer213functioning as a gate insulating layer, and a conductive layer223functioning as a gate. Here, a plurality of layers obtained by processing the same conductive film are shown with the same hatching pattern. The insulating layer211is positioned between the conductive layer221and the semiconductor layer231. The insulating layer213is positioned between the conductive layer223and the semiconductor layer231.

There is no particular limitation on the structure of the transistors included in the display device of this embodiment. For example, a planar transistor, a staggered transistor, an inverted staggered transistor, or the like can be used. A top-gate transistor structure or a bottom-gate transistor structure may be employed. Alternatively, gates may be provided above and below the semiconductor layer where a channel is formed.

The structure where the semiconductor layer where a channel is formed is held between two gates is used for the transistor201and the transistor205. The two gates may be connected to each other and supplied with the same signal to drive the transistor. Alternatively, a potential for controlling the threshold voltage may be supplied to one of the two gates and a potential for driving may be supplied to the other to control the threshold voltage of the transistor.

There is no particular limitation on the crystallinity of a semiconductor material used for the transistors, and any of an amorphous semiconductor and a semiconductor having crystallinity (a microcrystalline semiconductor, a polycrystalline semiconductor, a single crystal semiconductor, or a semiconductor partly including crystal regions) may be used. It is preferable to use a semiconductor having crystallinity, in which case deterioration of the transistor characteristics can be inhibited.

The semiconductor layer of the transistor preferably includes a metal oxide. That is, a transistor including a metal oxide in its channel formation region is preferably used for the display device of this embodiment.

As examples of the oxide semiconductor having crystallinity, a CAAC (c-axis aligned crystalline)-OS, an nc (nanocrystalline)-OS, and the like can be given.

Alternatively, a transistor containing silicon in its channel formation region (a Si transistor) may be used. As examples of silicon, single crystal silicon, polycrystalline silicon, amorphous silicon, and the like can be given. In particular, a transistor containing low-temperature polysilicon (LTPS) in its semiconductor layer (hereinafter also referred to as an LTPS transistor) can be used. The LTPS transistor has high field-effect mobility and favorable frequency characteristics.

With the use of Si transistors such as LTPS transistors, a circuit required to be driven at a high frequency (e.g., a source driver circuit) can be formed on the same substrate as a display portion. Thus, external circuits mounted on the display device can be simplified, and parts costs and mounting costs can be reduced.

An OS transistor has much higher field-effect mobility than a transistor containing amorphous silicon. In addition, the OS transistor has an extremely low leakage current between a source and a drain in an off state (hereinafter, also referred to as off-state current), and electric charge accumulated in a capacitor that is connected in series to the transistor can be retained for a long period. Furthermore, power consumption of the display device can be reduced with the use of an OS transistor.

To increase the emission luminance of the light-emitting element included in the pixel circuit, the amount of current fed through the light-emitting element needs to be increased. For this, it is necessary to increase the source-drain voltage of a driving transistor included in the pixel circuit. Since an OS transistor has a higher breakdown voltage between the source and the drain than a Si transistor, a high voltage can be applied between the source and the drain of the OS transistor. Accordingly, when an OS transistor is used as the driving transistor included in the pixel circuit, the amount of current flowing through the light-emitting element can be increased, so that the emission luminance of the light-emitting element can be increased.

When transistors operate in a saturation region, a change in source-drain current with respect to a change in gate-source voltage can be smaller in an OS transistor than in a Si transistor. Accordingly, when an OS transistor is used as the driving transistor in the pixel circuit, the amount of current flowing between the source and the drain can be set minutely by a change in gate-source voltage: hence, the amount of current flowing through the light-emitting element can be controlled. Accordingly, the number of gray levels in the pixel circuit can be increased.

Regarding saturation characteristics of current flowing when transistors operate in a saturation region, even in the case where the source-drain voltage of an OS transistor increases gradually, a more stable current (saturation current) can be fed through the OS transistor than through a Si transistor. Thus, by using an OS transistor as the driving transistor, a stable current can be fed through light-emitting elements even when the current-voltage characteristics of the organic EL devices vary, for example. In other words, when the OS transistor operates in the saturation region, the source-drain current hardly changes with an increase in the source-drain voltage: hence, the emission luminance of the light-emitting element can be stable.

As described above, with the use of an OS transistor as a driving transistor included in the pixel circuit, it is possible to achieve “inhibition of black-level degradation,” “increase in emission luminance,” “increase in gray level,” “inhibition of variation in light-emitting elements,” and the like.

It is particularly preferable that an oxide containing indium (In), gallium (Ga), and zinc (Zn) (also referred to as IGZO) be used for the semiconductor layer. Alternatively, it is preferable to use an oxide containing indium, tin, and zinc. Further alternatively, it is preferable to use an oxide containing indium, gallium, tin, and zinc. Alternatively, an oxide containing indium (In), aluminum (Al), and zinc (Zn) (also referred to as IAZO) is preferably used for the semiconductor layer. Alternatively, an oxide containing indium (In), aluminum (Al), gallium (Ga), and zinc (Zn) (also referred to as IAGZO) is preferably used for the semiconductor layer.

When the semiconductor layer is an In-M-Zn oxide, the atomic ratio of In is preferably higher than or equal to the atomic ratio of M in the In-M-Zn oxide. Examples of the atomic ratio of the metal elements in such an In-M-Zn oxide include In:M:Zn=1:1:1 or a composition in the neighborhood thereof, In:M:Zn=1:1:1.2 or a composition in the neighborhood thereof, In:M:Zn=2:1:3 or a composition in the neighborhood thereof, In:M:Zn=3:1:2 or a composition in the neighborhood thereof, In:M:Zn=4:2:3 or a composition in the neighborhood thereof, In:M:Zn=4:2:4.1 or a composition in the neighborhood thereof, In:M:Zn=5:1:3 or a composition in the neighborhood thereof, In:M:Zn=5:1:6 or a composition in the neighborhood thereof, In:M:Zn=5:1:7 or a composition in the neighborhood thereof, In:M:Zn=5:1:8 or a composition in the neighborhood thereof, In:M:Zn=6:1:6 or a composition in the neighborhood thereof, and In:M:Zn=5:2:5 or a composition in the neighborhood thereof. Note that a composition in the neighborhood includes the range of +30% of an intended atomic ratio.

For example, when the atomic ratio is described as In:Ga:Zn=4:2:3 or a composition in the neighborhood thereof, the case is included where the atomic proportion of Ga is greater than or equal to 1 and less than or equal to 3 and the atomic proportion of Zn is greater than or equal to 2 and less than or equal to 4 with the atomic proportion of In being 4. When the atomic ratio is described as In:Ga:Zn=5:1:6 or a composition in the neighborhood thereof, the case is included where the atomic proportion of Ga is greater than 0.1 and less than or equal to 2 and the atomic proportion of Zn is greater than or equal to 5 and less than or equal to 7 with the atomic proportion of In being 5. When the atomic ratio is described as In:Ga:Zn=1:1:1 or a composition in the neighborhood thereof, the case is included where the atomic proportion of Ga is greater than 0.1 and less than or equal to 2 and the atomic proportion of Zn is greater than 0.1 and less than or equal to 2 with the atomic proportion of In being 1.

The transistor included in the circuit164and the transistor included in the pixel portion107may have the same structure or different structures. One structure or two or more types of structures may be employed for a plurality of transistors included in the circuit164. Similarly, one structure or two or more types of structures may be employed for a plurality of transistors included in the pixel portion107.

All of the transistors included in the pixel portion107may be OS transistors or all of the transistors included in the pixel portion107may be Si transistors: alternatively, some of the transistors included in the pixel portion107may be OS transistors and the others may be Si transistors.

For example, when both an LTPS transistor and an OS transistor are used in the pixel portion107, the display device can have low power consumption and high driving capability. A structure where an LTPS transistor and an OS transistor are used in combination is referred to as LTPO in some cases. For example, preferably, an OS transistor is used as a transistor functioning as a switch for controlling conduction and non-conduction between wirings and an LTPS transistor is used as a transistor for controlling current.

For example, one of the transistors included in the pixel portion107functions as a transistor for controlling current flowing through the light-emitting element and can be referred to as a driving transistor. One of a source and a drain of the driving transistor is electrically connected to the pixel electrode of the light-emitting element. An LTPS transistor is preferably used as the driving transistor. In that case, the amount of current flowing through the light-emitting element can be increased in the pixel circuit.

Another transistor included in the pixel portion107functions as a switch for controlling selection and non-selection of the pixel and can be referred to as a selection transistor. A gate of the selection transistor is electrically connected to a gate line, and one of a source and a drain thereof is electrically connected to a signal line. An OS transistor is preferably used as the selection transistor. In that case, the gray level of the pixel can be maintained even with an extremely low frame frequency (e.g., lower than or equal to 1 fps); thus, power consumption can be reduced by stopping the driver in displaying a still image.

As described above, the display device of one embodiment of the present invention can have all of a high aperture ratio, high resolution, high display quality, and low power consumption.

Note that the display device of one embodiment of the present invention has a structure including the OS transistor and the light-emitting element having an MML (metal maskless) structure. With this structure, the leakage current that might flow through the transistor and the lateral leakage current that might flow between adjacent light-emitting elements can be extremely low: With the structure, a viewer can notice any one or more of the image crispness, the image sharpness, a high chroma, and a high contrast ratio in an image displayed on the display device. When the leakage current that would flow through the transistor and the lateral leakage current between the light-emitting elements are extremely low; light leakage that might occur in black display (what is called black-level degradation) or the like can be minimized.

In particular, in the case where a light-emitting element having the MML structure employs the above-described SBS structure, a layer provided between light-emitting elements is disconnected: accordingly, lateral leakage current can be prevented or be made extremely low. FIG.70B1and FIG.70B2illustrate other structure examples of transistors.

A transistor209and a transistor210each include the conductive layer221functioning as a gate, the insulating layer211functioning as a gate insulating layer, the semiconductor layer231including a channel formation region231iand a pair of low-resistance regions231n, the conductive layer222aconnected to one of the pair of low-resistance regions231n, the conductive layer222bconnected to the other of the pair of low-resistance regions231n, an insulating layer225functioning as a gate insulating layer, the conductive layer223functioning as a gate, and the insulating layer215covering the conductive layer223. The insulating layer211is positioned between the conductive layer221and the channel formation region231i. The insulating layer225is positioned at least between the conductive layer223and the channel formation region231i. Furthermore, an insulating layer218covering the transistor may be provided.

FIG.70B1illustrates an example of the transistor209in which the insulating layer225covers the upper surface and the side surface of the semiconductor layer231. The conductive layer222aand the conductive layer222bare connected to the low-resistance regions231nthrough openings provided in the insulating layer225and the insulating layer215. One of the conductive layer222aand the conductive layer222bfunctions as a source, and the other functions as a drain.

Meanwhile, in the transistor210illustrated in FIG.70B2C, the insulating layer225overlaps with the channel formation region231iof the semiconductor layer231and does not overlap with the low-resistance regions231n. The structure illustrated in FIG.70B2can be formed by processing the insulating layer225with the conductive layer223as a mask, for example. In FIG.70B2, the insulating layer215is provided to cover the insulating layer225and the conductive layer223, and the conductive layer222aand the conductive layer222bare connected to the low-resistance regions231nthrough the openings in the insulating layer215.

A connection portion204is provided in a region of the substrate151where the substrate152does not overlap. In the connection portion204, the wiring165is electrically connected to the FPC172through a conductive layer166and a connection layer242. An example is described in which the conductive layer166has a stacked-layer structure of a conductive film obtained by processing the same conductive film as the conductive layer224R, the conductive layer224G, and the conductive layer224B, a conductive film obtained by processing the same conductive film as the conductive layer111R, the conductive layer111G, and the conductive layer111B, and a conductive film obtained by processing the same conductive film as the conductive layer112R, the conductive layer112G, and the conductive layer112B. The conductive layer166is exposed on the upper surface of the connection portion204. Thus, the connection portion204and the FPC172can be electrically connected to each other through the connection layer242.

A light-blocking layer117is preferably provided on the surface of the substrate152that faces the substrate151. The light-blocking layer117can be provided between adjacent light-emitting elements, in the connection portion140, and in the circuit164, for example. A variety of optical members can be provided on the outer surface of the substrate152.

The material that can be used for the substrate120can be used for each of the substrate151and the substrate152.

The material that can be used for the resin layer122can be used for the adhesive layer142.

As the connection layer242, an anisotropic conductive film (ACF), an anisotropic conductive paste (ACP), or the like can be used.

FIG.71illustrates a modification example of the structure illustrated inFIG.70A, and in the example, the light-emitting element130R, the light-emitting element130G, and the light-emitting element130B have the structure illustrated inFIG.10.FIG.72illustrates a modification example of the structure illustrated inFIG.70A, and in the example, the light-emitting element130R, the light-emitting element130G, and the light-emitting element130B have the structure illustrated inFIG.14.

The display device100H illustrated inFIG.73Ais a modification example of the display device100G illustrated inFIG.70Aand differs from the display device100G mainly in including the coloring layer132R, the coloring layer132G, and the coloring layer132B.

In the display device100H, the light-emitting element130includes a region overlapping with one of the coloring layer132R, the coloring layer132G, and the coloring layer132B. The coloring layer132R, the coloring layer132G, and the coloring layer132B can be provided on a surface of the substrate152on the substrate151side. The end portion of the coloring layer132R, the end portion of the coloring layer132G, and the end portion of the coloring layer132B can overlap with the light-blocking layer117. Regarding the display device100H,FIG.19Acan be referred to for the details of the structure of the light-emitting element130, for example.

In the display device100H, the light-emitting element130can emit white light, for example. For example, the coloring layer132R transmits red light, the coloring layer132G transmits green light, and the coloring layer132B transmits blue light. Note that in the display device100H the coloring layer132R, the coloring layer132G, and the coloring layer132B may be provided between the protective layer131and the adhesive layer142. In that case, the protective layer131is preferably planarized as illustrated inFIG.19A.

AlthoughFIG.70A,FIG.73A, and the like illustrate an example where the upper surface of the layer128includes a flat portion, the shape of the layer128is not particularly limited. FIG.73B1to FIG.73B3illustrate variation examples of the layer128.

As illustrated in FIG.73B1to FIG.73B3, the upper surface of the layer128can have a shape such that its center and the vicinity thereof are depressed, i.e., a shape including a concave surface, in a cross-sectional view.

As illustrated in FIG.73B2, the upper surface of the layer128can have a shape such that its center and the vicinity thereof bulge, i.e., a shape including a convex surface, in a cross-sectional view.

The upper surface of the layer128may include one or both of a convex surface and a concave surface. The number of convex surfaces and the number of concave surfaces included in the upper surface of the layer128are not limited and can each be one or more.

The level of the upper surface of the layer128and the level of the upper surface of the conductive layer224R may be equal to or substantially equal to each other, or may be different from each other. For example, the level of the upper surface of the layer128may be either lower or higher than the level of the upper surface of the conductive layer224R.

FIG.73B1can be regarded as illustrating an example where the layer128fits in the depressed portion formed in the conductive layer224R. By contrast, as illustrated in FIG.73B3, the layer128may exist also outside the depressed portion formed in the conductive layer224R, that is, the layer128may be formed to have an upper surface wider than the depressed portion.

FIG.74A, FIG.74B1, FIG.74B2, and FIG.74B3are modification examples of the structures illustrated inFIG.73A, FIG.73B1, FIG.73B2, and FIG.73B3, respectively, and in each example, the light-emitting element130R, the light-emitting element130G, and the light-emitting element130B have the structure illustrated inFIG.10.FIG.75AtoFIG.75Cillustrate modification examples of the structures illustrated in FIG.73B1to FIG.73B3, respectively, and in each example, the EL layer113R has the structure illustrated inFIG.14.

This embodiment can be combined with any of the other embodiments as appropriate. In this specification, in the case where a plurality of structure examples are described in one embodiment, the structure examples can be combined as appropriate.

In this embodiment, light-emitting elements that can be used for the display device of one embodiment of the present invention will be described.

As illustrated inFIG.76A, the light-emitting element includes an EL layer763between a pair of electrodes (a lower electrode761and an upper electrode762). The EL layer763can be formed of a plurality of layers such as a layer780, a light-emitting layer771, and a layer790.

The light-emitting layer771contains at least a light-emitting substance.

In the case where the lower electrode761is an anode and the upper electrode762is a cathode, the layer780includes one or more of a layer containing a substance with a high hole-injection property (a hole-injection layer), a layer containing a substance with a high hole-transport property (a hole-transport layer), and a layer containing a substance with a high electron-blocking property (an electron-blocking layer). Furthermore, the layer790includes one or more of a layer containing a substance with a high electron-injection property (an electron-injection layer), a layer containing a substance with a high electron-transport property (an electron-transport layer), and a layer containing a substance with a high hole-blocking property (a hole-blocking layer). In the case where the lower electrode761is a cathode and the upper electrode762is an anode, the above structures of the layer780and the layer790are replaced with each other.

The structure including the layer780, the light-emitting layer771, and the layer790, which is provided between a pair of electrodes, can function as a single light-emitting unit, and the structure inFIG.76Ais referred to as a single structure in this specification.

FIG.76Bis a variation example of the EL layer763included in the light-emitting element illustrated inFIG.76A. Specifically, the light-emitting element illustrated inFIG.76Bincludes a layer781over the lower electrode761, a layer782over the layer781, the light-emitting layer771over the layer782, a layer791over the light-emitting layer771, a layer792over the layer791, and the upper electrode762over the layer792.

In the case where the lower electrode761is an anode and the upper electrode762is a cathode, the layer781can be a hole-injection layer, the layer782can be a hole-transport layer, the layer791can be an electron-transport layer, and the layer792can be an electron-injection layer, for example. In the case where the lower electrode761is a cathode and the upper electrode762is an anode, the layer781can be an electron-injection layer, the layer782can be an electron-transport layer, the layer791can be a hole-transport layer, and the layer792can be a hole-injection layer. With such a layer structure, carriers can be efficiently injected to the light-emitting layer771, and the efficiency of the recombination of carriers in the light-emitting layer771can be increased.

Note that structures in which a plurality of light-emitting layers (light-emitting layers771,772, and773) are provided between the layer780and the layer790as illustrated inFIG.76CandFIG.76Dare variations of the single structure. AlthoughFIG.76CandFIG.76Dillustrate the examples where three light-emitting layers are included, the light-emitting element having a single structure may include two or four or more light-emitting layers. In addition, the light-emitting element having a single structure may include a buffer layer between two light-emitting layers. The buffer layer can be formed using a material that can be used for the hole-transport layer or the electron-transport layer, for example.

A structure where a plurality of light-emitting units (a light-emitting unit763aand a light-emitting unit763b) are connected in series with a charge-generation layer785(also referred to as an intermediate layer) therebetween as illustrated inFIG.76EandFIG.76Fis referred to as a tandem structure in this specification. Note that the tandem structure may be referred to as a stack structure. The tandem structure enables a light-emitting element capable of high-luminance light emission. Furthermore, the tandem structure reduces the amount of current needed for obtaining the same luminance as compared with a single structure, and thus can improve the reliability.

Note thatFIG.76DandFIG.76Fillustrate examples where the display device includes a layer764overlapping with the light-emitting element.FIG.76Dillustrates an example in which the layer764overlaps with the light-emitting element illustrated inFIG.76C, andFIG.76Fillustrates an example in which the layer764overlaps with the light-emitting element illustrated inFIG.76E. InFIG.76DandFIG.76F, a conductive film transmitting visible light is used for the upper electrode762to extract light to the upper electrode762side.

One or both of a color conversion layer and a color filter (coloring layer) can be used as the layer764.

InFIG.76CandFIG.76D, light-emitting substances that emit light of the same color, or moreover, the same light-emitting substance may be used for the light-emitting layer771, the light-emitting layer772, and the light-emitting layer773. For example, a light-emitting substance emitting blue light may be used for the light-emitting layer771, the light-emitting layer772, and the light-emitting layer773. In a subpixel that emits blue light, blue light emitted from the light-emitting element can be extracted. In a subpixel that emits red light and a subpixel that emits green light, by providing a color conversion layer as the layer764illustrated inFIG.76D, blue light emitted from the light-emitting element can be converted into light with a longer wavelength, and red light or green light can be extracted. As the layer764, both a color conversion layer and a coloring layer are preferably used. In some cases, part of light emitted from the light-emitting element is transmitted through the color conversion layer without being converted. When light transmitted through the color conversion layer is extracted through the coloring layer, light other than light of the intended color can be absorbed by the coloring layer, and color purity of light exhibited by a subpixel can be improved.

Alternatively, light-emitting substances emitting light of different colors may be used for the light-emitting layer771, the light-emitting layer772, and the light-emitting layer773. White light emission can be obtained when the light-emitting layer771, the light-emitting layer772, and the light-emitting layer773emit light of complementary colors. The light-emitting element having a single structure preferably includes a light-emitting layer containing a light-emitting substance emitting blue light and a light-emitting layer containing a light-emitting substance emitting visible light with a longer wavelength than blue light, for example.

In the case where the light-emitting element having a single structure includes three light-emitting layers, for example, a light-emitting layer containing a light-emitting substance emitting red (R) light, a light-emitting layer containing a light-emitting substance emitting green (G) light, and a light-emitting layer containing a light-emitting substance emitting blue (B) light are preferably included. The stacking order of the light-emitting layers can be RGB or RBG from an anode side, for example. In that case, a buffer layer may be provided between R and G or between R and B.

For example, in the case where the light-emitting element having a single structure includes two light-emitting layers, the light-emitting element preferably includes a light-emitting layer containing a light-emitting substance that emits blue (B) light and a light-emitting layer containing a light-emitting substance that emits yellow (Y) light. Such a structure may be referred to as a BY single structure.

A coloring layer may be provided as the layer764illustrated inFIG.76D. When white light passes through the coloring layer, light of a desired color can be obtained.

The light-emitting element emitting white light preferably contains two or more light-emitting layers. For example, when white light emission is obtained using two light-emitting layers, two or more light-emitting layers are selected such that their emission colors are complementary. For example, when an emission color of a first light-emitting layer and an emission color of a second light-emitting layer are complementary colors, the light-emitting element can be configured to emit white light as a whole. To obtain white light emission by using three or more light-emitting layers, the light-emitting element is configured to emit white light as a whole by combining emission colors of the three or more light-emitting layers.

InFIG.76EandFIG.76F, light-emitting substances that emit light of the same color, or moreover, the same light-emitting substance may be used for the light-emitting layer771and the light-emitting layer772.

For example, in light-emitting elements included in subpixels emitting light of different colors, a light-emitting substance that emits blue light can be used for each of the light-emitting layer771and the light-emitting layer772. In a subpixel that emits blue light, blue light emitted from the light-emitting element can be extracted. In the subpixel that emits red light and the subpixel that emits green light, by providing a color conversion layer as the layer764illustrated inFIG.76F, blue light emitted from the light-emitting element can be converted into light with a longer wavelength, and red light or green light can be extracted. As the layer764, both a color conversion layer and a coloring layer are preferably used.

In the case where the light-emitting element having the structure illustrated inFIG.76EorFIG.76Fis used for the subpixels emitting different colors, the subpixels may use different light-emitting substances. Specifically, in the light-emitting element included in the subpixel emitting red light, a light-emitting substance that emits red light can be used for each of the light-emitting layer771and the light-emitting layer772. Similarly, in the light-emitting element included in the subpixel emitting green light, a light-emitting substance that emits green light can be used for each of the light-emitting layer771and the light-emitting layer772. In the light-emitting element included in the subpixel emitting blue light, a light-emitting substance that emits blue light can be used for each of the light-emitting layer771and the light-emitting layer772. In light-emitting elements included in subpixels emitting light of different colors, a light-emitting substance that emits blue light can be used for each of the light-emitting layer771and the light-emitting layer772. A display device having such a structure can be regarded as employing a light-emitting element with the tandem structure and the SBS structure. Thus, advantages of both the tandem structure and the SBS structure can be achieved. Accordingly, a light-emitting element being capable of high-luminance light emission and having high reliability can be obtained.

InFIG.76EandFIG.76F, light-emitting substances emitting light of different colors may be used for the light-emitting layer771and the light-emitting layer772. White light emission can be obtained when the light-emitting layer771and the light-emitting layer772emit light of complementary colors. A coloring layer may be provided as the layer764illustrated inFIG.76F. When white light passes through the coloring layer, light of a desired color can be obtained.

AlthoughFIG.76EandFIG.76Fillustrate examples where the light-emitting unit763aincludes one light-emitting layer771and the light-emitting unit763bincludes one the light-emitting layer772, one embodiment of the present invention is not limited thereto. Each of the light-emitting unit763aand the light-emitting unit763bmay include two or more light-emitting layers.

In addition, althoughFIG.76EandFIG.76Fillustrate the light-emitting element including two light-emitting units, one embodiment of the present invention is not limited thereto. The light-emitting element may include three or more light-emitting units.

Specifically, structures of the light-emitting element illustrated inFIG.77AtoFIG.77Ccan be given.

FIG.77Aillustrates a structure including three light-emitting units. Note that a structure including two light-emitting units and a structure including three light-emitting units may be referred to as a two-unit tandem structure and a three-unit tandem structure, respectively.

As illustrated inFIG.77A, a plurality of light-emitting units (the light-emitting unit763a, the light-emitting unit763b, and the light-emitting unit763c) are connected in series through the charge-generation layers785. The light-emitting unit763aincludes a layer780a, the light-emitting layer771, and a layer790a. The light-emitting unit763bincludes a layer780b, the light-emitting layer772, and a layer790b. The light-emitting unit763cincludes a layer780c, the light-emitting layer773, and a layer790c. Note that the layer780ccan have a structure applicable to the layer780aand the layer780b, and the layer790ccan have a structure applicable to the layer790aand the layer790b.

InFIG.77A, the light-emitting layer771, the light-emitting layer772, and the light-emitting layer preferably contain light-emitting substances that emit light of the same color. Specifically, the light-emitting layer771, the light-emitting layer772, and the light-emitting layer773can each contain a light-emitting substance that emits red (R) light (a so-called R\R\R three-unit tandem structure): the light-emitting layer771, the light-emitting layer772, and the light-emitting layer773can each contain a light-emitting substance that emits green (G) light (a so-called a G\G\G three-unit tandem structure): or the light-emitting layer771, the light-emitting layer772, and the light-emitting layer773can each contain a light-emitting substance that emits blue (B) light (a so-called B\B\B three-unit tandem structure). Note that “a\b” means that a light-emitting unit containing a light-emitting substance that emits light of b is provided over a light-emitting unit containing a light-emitting substance that emits light of a with a charge-generation layer therebetween, where a and b represent colors.

InFIG.77A, light-emitting substances that emit light of different colors may be used for some or all of the light-emitting layer771, the light-emitting layer772, and the light-emitting layer773. Examples of a combination of emission colors for the light-emitting layer771, the light-emitting layer772, and the light-emitting layer773include blue (B) for two of them and yellow (Y) for the other; and red (R) for one of them, green (G) for another, and blue (B) for the other.

Note that the structure containing the light-emitting substances that emit light of the same color is not limited to the above structure. For example, a light-emitting element with a tandem structure may be employed in which light-emitting units each including a plurality of light-emitting layers are stacked as illustrated inFIG.77B.FIG.77Billustrates a structure in which two light-emitting units the light-emitting unit763aand the light-emitting unit763b) are connected in series with the charge-generation layer785therebetween. The light-emitting unit763aincludes the layer780a, a light-emitting layer771a, a light-emitting layer771b, a light-emitting layer771c, and the layer790a. The light-emitting unit763bincludes the layer780b, a light-emitting layer772a, a light-emitting layer772b, a light-emitting layer772c, and the layer790b.

InFIG.77B, the light-emitting unit763ais configured to emit white (W) light by selecting light-emitting substances for the light-emitting layer771a, the light-emitting layer771b, and the light-emitting layer771cso that their emission colors are complementary colors. Furthermore, the light-emitting unit763bis configured to emit white (W) light by selecting light-emitting substances for the light-emitting layer772a, the light-emitting layer772b, and the light-emitting layer772care selected so that their emission colors are complementary colors. That is, the structure illustrated inFIG.77Bis a two-unit tandem structure of WWW. Note that there is no particular limitation on the stacking order of the light-emitting substances having complementary emission colors. The practitioner can select the optimal stacking order as appropriate. Although not illustrated, a three-unit tandem structure of WWW or a tandem structure with four or more units may be employed.

The following structure can be given: a BY or Y\B two-unit tandem structure including a light-emitting unit that emits yellow (Y) light and a light-emitting unit that emits blue (B) light; an R·G\B or B\R·G two-unit tandem structure including a light-emitting unit that emits red (R) light and green (G) light and a light-emitting unit that emits blue (B) light: a B\Y\B three-unit tandem structure including a light-emitting unit that emits blue (B) light, a light-emitting unit that emits yellow (Y) light, and a light-emitting unit that emits blue (B) light in this order: a B\YG\B three-unit tandem structure including a light-emitting unit that emits blue (B) light, a light-emitting unit that emits yellow green (YG) light, and a light-emitting unit that emits blue (B) light in this order; and a B\G\B three-unit tandem structure including a light-emitting unit that emits blue (B) light, a light-emitting unit that emits green (G) light, and a light-emitting unit that emits blue (B) light in this order. Note that “a\b” means that one light-emitting unit contains a light-emitting substance that emits light of a and a light-emitting substance that emits light of b.

As illustrated inFIG.77C, a light-emitting unit including one light-emitting layer and a light-emitting unit including a plurality of light-emitting layers may be used in combination.

Specifically, in the structure illustrated inFIG.77C, a plurality of light-emitting units (the light-emitting unit763a, the light-emitting unit763b, and the light-emitting unit763c) are connected in series through the charge-generation layers785. The light-emitting unit763aincludes the layer780a, the light-emitting layer771, and the layer790a. The light-emitting unit763bincludes a layer780b, the light-emitting layer772a, the light-emitting layer772b, the light-emitting layer772c, and the layer790b. The light-emitting unit763cincludes the layer780c, the light-emitting layer773, and the layer790c.

As the structure illustrated inFIG.77C, for example, a three-unit tandem structure of B\R·G·YG\B in which the light-emitting unit763ais a light-emitting unit that emits blue (B) light, the light-emitting unit763bis a light-emitting unit that emits red (R), green (G), and yellow-green (YG) light, and the light-emitting unit763cis a light-emitting unit that emits blue (B) light can be employed.

Examples of the number of stacked light-emitting units and the order of colors from the anode side include a two-unit structure of B and Y, a two-unit structure of B and a light-emitting unit X, a three-unit structure of B, Y, and B, and a three-unit structure of B, X, and B. Examples of the number of light-emitting layers stacked in the light-emitting unit X and the order of colors from an anode side include a two-layer structure of R and Y, a two-layer structure of R and G, a two-layer structure of G and R, a three-layer structure of G, R, and G, and a three-layer structure of R. G, and R. Another layer may be provided between two light-emitting layers.

Also inFIG.76CandFIG.76D, the layer780and the layer790may each independently have a stacked-layer structure of two or more layers as illustrated inFIG.76B.

InFIG.76EandFIG.76F, the light-emitting unit763aincludes the layer780a, the light-emitting layer771, and the layer790a, and the light-emitting unit763bincludes the layer780b, the light-emitting layer772, and the layer790b.

In the case where the lower electrode761is an anode and the upper electrode762is a cathode, the layer780aand the layer780beach include one or more of a hole-injection layer, a hole-transport layer, and an electron-blocking layer. The layer790aand the layer790beach include one or more of an electron-injection layer, an electron-transport layer, and a hole-blocking layer. In the case where the lower electrode761is a cathode and the upper electrode762is an anode, the structures of the layer780aand the layer790aare replaced with each other, and the structures of the layer780band the layer790bare also replaced with each other.

In the case where the lower electrode761is an anode and the upper electrode762is a cathode, for example, the layer780aincludes a hole-injection layer and a hole-transport layer over the hole-injection layer, and may further include an electron-blocking layer over the hole-transport layer. The layer790aincludes an electron-transport layer, and may further include a hole-blocking layer between the light-emitting layer771and the electron-transport layer. The layer780bincludes a hole-transport layer, and may further include an electron-blocking layer over the hole-transport layer. The layer790bincludes an electron-transport layer and an electron-injection layer over the electron-transport layer, and may further include a hole-blocking layer between the light-emitting layer771and the electron-transport layer. In the case where the lower electrode761is a cathode and the upper electrode762is an anode, for example, the layer780aincludes an electron-injection layer and an electron-transport layer over the electron-injection layer, and may further include a hole-blocking layer over the electron-transport layer. The layer790aincludes a hole-transport layer, and may further include an electron-blocking layer between the light-emitting layer771and the hole-transport layer. The layer780bincludes an electron-transport layer, and may further include a hole-blocking layer over the electron-transport layer. The layer790bincludes a hole-transport layer and a hole-injection layer over the hole-transport layer, and may further include an electron-blocking layer between the light-emitting layer771and the hole-transport layer.

In the case of fabricating a light-emitting element having a tandem structure, two light-emitting units are stacked with the charge-generation layer785therebetween. The charge-generation layer785includes at least a charge-generation region. The charge-generation layer785has a function of injecting electrons into one of the two light-emitting units and injecting holes into the other when voltage is applied between the pair of electrodes.

Next, materials that can be used for the light-emitting element will be described.

A conductive film transmitting visible light is used as the electrode through which light is extracted, which is either the lower electrode761or the upper electrode762. A conductive film reflecting visible light is preferably used as the electrode through which light is not extracted. In the case where a display device includes a light-emitting element emitting infrared light, a conductive film transmitting visible light and infrared light is used as the electrode through which light is extracted, and a conductive film reflecting visible light and infrared light is preferably used as the electrode through which light is not extracted.

A conductive film transmitting visible light may be used as the electrode through which light is not extracted. In that case, the electrode is preferably placed between a reflective layer and the EL layer763. In other words, light emitted from the EL layer763may be reflected by the reflective layer to be extracted from the display device.

As a material that forms the pair of electrodes of the light-emitting element, a metal, an alloy, an electrically conductive compound, a mixture thereof, or the like can be used as appropriate. Specific examples of the material include metals such as aluminum, magnesium, titanium, chromium, manganese, iron, cobalt, nickel, copper, gallium, zinc, indium, tin, molybdenum, tantalum, tungsten, palladium, gold, platinum, silver, yttrium, and neodymium, and an alloy containing any of these metals in appropriate combination. Other examples of the material include In—Sn oxide, In—Si—Sn oxide (also referred to as ITSO), In—Zn oxide, and In—W—Zn oxide. Examples of the material include an aluminum alloy, an alloy of silver and magnesium, and an alloy containing silver, such as APC. Other example of the material include elements belonging to Group 1 or Group 2 of the periodic table, which are not exemplified above (e.g., lithium, cesium, calcium, and strontium), rare earth metals such as europium and ytterbium, an alloy containing any of these metals in appropriate combination, and graphene.

In addition, the light-emitting element preferably also employs a microcavity structure. Therefore, one of the pair of electrodes of the light-emitting element is preferably an electrode having properties of transmitting and reflecting visible light (a transflective electrode), and the other is preferably an electrode having a property of reflecting visible light (a reflective electrode). When the light-emitting element has a microcavity structure, light obtained from the light-emitting layer can be resonated between the electrodes, whereby light emitted from the light-emitting element can be intensified.

Note that the transflective electrode can have a stacked-layer structure of a conductive layer that can be used as a reflective electrode and a conductive layer having a visible-light-transmitting property (also referred to as a transparent electrode).

The transflective electrode has a visible light reflectance higher than or equal to 10% and lower than or equal to 95%, preferably higher than or equal to 30% and lower than or equal to 80%. The reflective electrode has a visible light reflectance higher than or equal to 40% and lower than or equal to 100%, preferably higher than or equal to 70% and lower than or equal to 100%. These electrodes preferably have a resistivity less than or equal to 1×10−2Ωcm.

The light-emitting element includes at least the light-emitting layer. The light-emitting element may further include, as a layer other than the light-emitting layer, a layer containing a substance with a high hole-injection property, a substance with a high hole-transport property, a hole-blocking material, a substance with a high electron-transport property, an electron-blocking material, a substance with a high electron-injection property, a substance with a bipolar property (a substance with a high electron-transport property and a high hole-transport property), or the like. For example, the light-emitting element can include one or more of a hole-injection layer, a hole-transport layer, a hole-blocking layer, a charge-generation layer, an electron-blocking layer, an electron-transport layer, and an electron-injection layer in addition to the light-emitting layer.

Either a low molecular compound or a high molecular compound can be used in the light-emitting element, and an inorganic compound may be included. Each layer included in the light-emitting element can be formed by any of the following methods: an evaporation method (including a vacuum evaporation method), a transfer method, a printing method, an ink-jet method, a coating method, and the like.

The light-emitting layer contains one or more kinds of light-emitting substances. As the light-emitting substance, a substance exhibiting an emission color of blue, violet, bluish violet, green, yellowish green, yellow, orange, red, or the like is used as appropriate. Alternatively, as the light-emitting substance, a substance emitting near-infrared light can be used.

Examples of the light-emitting substance include a fluorescent material, a phosphorescent material, a TADF material, and a quantum dot material.

Examples of a fluorescent material include a pyrene derivative, an anthracene derivative, a triphenylene derivative, a fluorene derivative, a carbazole derivative, a dibenzothiophene derivative, a dibenzofuran derivative, a dibenzoquinoxaline derivative, a quinoxaline derivative, a pyridine derivative, a pyrimidine derivative, a phenanthrene derivative, and a naphthalene derivative.

Examples of a phosphorescent material include an organometallic complex (particularly an iridium complex) having a 4H-triazole skeleton, a 1H-triazole skeleton, an imidazole skeleton, a pyrimidine skeleton, a pyrazine skeleton, or a pyridine skeleton: an organometallic complex (particularly an iridium complex) having a phenylpyridine derivative including an electron-withdrawing group as a ligand: a platinum complex; and a rare earth metal complex.

The light-emitting layer may contain one or more kinds of organic compounds (e.g., a host material and an assist material) in addition to the light-emitting substance (a guest material). As one or more kinds of organic compounds, one or both of a substance with a high hole-transport property (a hole-transport material) and a substance with a high electron-transport property (an electron-transport material) can be used. As the hole-transport material, it is possible to use a material having a high hole-transport property which can be used for the hole-transport layer and will be described later. As the electron-transport material, it is possible to use a material having a high electron-transport property which can be used for the electron-transport layer and will be described later. Alternatively, as one or more kinds of organic compounds, a bipolar material or a TADF material may be used.

The light-emitting layer preferably contains a phosphorescent material and a combination of a hole-transport material and an electron-transport material that easily forms an exciplex, for example. Such a structure makes it possible to efficiently obtain light emission using ExTET (Exciplex-Triplet Energy Transfer), which is energy transfer from an exciplex to a light-emitting substance (a phosphorescent material). When a combination is selected to form an exciplex that exhibits light emission whose wavelength overlaps with the wavelength of the lowest-energy-side absorption band of the light-emitting substance, energy can be transferred smoothly and light emission can be obtained efficiently. With this structure, high efficiency, low-voltage driving, and a long lifetime of the light-emitting element can be achieved at the same time.

The hole-injection layer injects holes from the anode to the hole-transport layer and contains a material with a high hole-injection property. Examples of a material with a high hole-injection property include an aromatic amine compound and a composite material containing a hole-transport material and an acceptor material (electron-accepting material).

As the hole-transport material, it is possible to use a material having a high hole-transport property which can be used for the hole-transport layer and will be described later.

As the acceptor material, an oxide of a metal belonging to Group 4 to Group 8 of the periodic table can be used, for example. Specific examples include molybdenum oxide, vanadium oxide, niobium oxide, tantalum oxide, chromium oxide, tungsten oxide, manganese oxide, and rhenium oxide. Among these, molybdenum oxide is particularly preferable since it is stable in the air, has a low hygroscopic property, and is easy to handle. An organic acceptor material containing fluorine can be used. An organic acceptor material such as a quinodimethane derivative, a chloranil derivative, or a hexaazatriphenylene derivative can be used.

For example, a hole-transport material and a material containing an oxide of a metal belonging to Group 4 to Group 8 of the periodic table (typically, molybdenum oxide) may be used as the material having a high hole-injection property.

The hole-transport layer transports holes injected from the anode by the hole-injection layer, to the light-emitting layer. The hole-transport layer contains a hole-transport material. As the hole-transport material, a substance having a hole mobility higher than or equal to 1×10−6cm2/Vs is preferable. Note that other substances can also be used as long as the substances have a hole-transport property higher than an electron-transport property. As the hole-transport material, a material with a high hole-transport property, such as π-electron rich heteroaromatic compound (e.g., a carbazole derivative, a thiophene derivative, or a furan derivative) or an aromatic amine (a compound having an aromatic amine skeleton), is preferable.

The electron-blocking layer is provided in contact with the light-emitting layer. The electron-blocking layer has a hole-transport property and contains a material capable of blocking electrons. Any of the materials having an electron-blocking property among the above hole-transport materials can be used for the electron-blocking layer.

The electron-blocking layer has a hole-transport property, and thus can also be referred to as a hole-transport layer. A layer having an electron-blocking property among the hole-transport layers can also be referred to as an electron-blocking layer.

The electron-transport layer transports electrons injected from the cathode by the electron-injection layer, to the light-emitting layer. The electron-transport layer contains an electron-transport material. As the electron-transport material, a substance having an electron mobility higher than or equal to 1×10−6cm2/Vs is preferable. Note that other substances can also be used as long as the substances have an electron-transport property higher than a hole-transport property: As the electron-transport material, any of the following materials with a high electron-transport property can be used, for example: a metal complex having a quinoline skeleton, a metal complex having a benzoquinoline skeleton, a metal complex having an oxazole skeleton, a metal complex having a thiazole skeleton, an oxadiazole derivative, a triazole derivative, an imidazole derivative, an oxazole derivative, a thiazole derivative, a phenanthroline derivative, a quinoline derivative having a quinoline ligand, a benzoquinoline derivative, a quinoxaline derivative, a dibenzoquinoxaline derivative, a pyridine derivative, a bipyridine derivative, a pyrimidine derivative, and a π-electron deficient heteroaromatic compound such as a nitrogen-containing heteroaromatic compound.

The hole-blocking layer is provided in contact with the light-emitting layer. The hole-blocking layer has an electron-transport property and contains a material capable of blocking holes. Any of the materials having a hole-blocking property among the above electron-transport materials can be used for the hole-blocking layer.

The hole-blocking layer has an electron-transport property, and thus can also be referred to as an electron-transport layer. A layer having a hole-blocking property among the electron-transport layers can also be referred to as a hole-blocking layer.

The electron-injection layer injects electrons from the cathode to the electron-transport layer and contains a material with a high electron-injection property. As the material with a high electron-injection property, an alkali metal, an alkaline earth metal, or a compound thereof can be used. As the material with a high electron-injection property, a composite material containing an electron-transport material and a donor material (electron-donating material) can also be used.

The difference between the LUMO level of the substance with a high electron-injection property and the work function value of the material used for the cathode is preferably small (specifically, smaller than or equal to 0.5 eV).

The electron-injection layer can be formed using, for example, an alkali metal, an alkaline earth metal, or a compound thereof, such as lithium, cesium, ytterbium, lithium fluoride (LiF), cesium fluoride (CsF), calcium fluoride (CaFx, where X is a given number), 8-(quinolinolato) lithium (abbreviation: Liq), 2-(2-pyridyl) phenolatolithium (abbreviation: LiPP), 2-(2-pyridyl)-3-pyridinolatolithium (abbreviation: LiPPy), 4-phenyl-2-(2-pyridyl) phenolatolithium (abbreviation: LiPPP), lithium oxide (LiOx), or cesium carbonate. The electron-injection layer may have a stacked-layer structure of two or more layers. The stacked-layer structure can be, for example, a structure where lithium fluoride is used for the first layer and ytterbium is used for the second layer.

The electron-injection layer may contain an electron-transport material. For example, a compound having an unshared electron pair and an electron deficient heteroaromatic ring can be used as the electron-transport material. Specifically, a compound having at least one of a pyridine ring, a diazine ring (a pyrimidine ring, a pyrazine ring, or a pyridazine ring), and a triazine ring can be used.

Note that the lowest unoccupied molecular orbital (LUMO) level of the organic compound having an unshared electron pair is preferably higher than or equal to −3.6 eV and lower than or equal to −2.3 eV. In general, the highest occupied molecular orbital (HOMO) level and the LUMO level of an organic compound can be estimated by CV (cyclic voltammetry), photoelectron spectroscopy, optical absorption spectroscopy, inverse photoelectron spectroscopy, or the like.

As described above, the charge-generation layer includes at least a charge-generation region. The charge-generation region preferably contains an acceptor material, and for example, preferably contains a hole-transport material and an acceptor material which can be used for the hole-injection layer.

The charge-generation layer preferably includes a layer containing a material having a high electron-injection property. The layer can also be referred to as an electron-injection buffer layer. The electron-injection buffer layer is preferably provided between the charge-generation region and the electron-transport layer. By provision of the electron-injection buffer layer, an injection barrier between the charge-generation region and the electron-transport layer can be lowered: thus, electrons generated in the charge-generation region can be easily injected into the electron-transport layer.

The electron-injection buffer layer preferably contains an alkali metal or an alkaline earth metal, and for example, can contain an alkali metal compound or an alkaline earth metal compound. Specifically, the electron-injection buffer layer preferably contains an inorganic compound containing an alkali metal and oxygen or an inorganic compound containing an alkaline earth metal and oxygen, further preferably contains an inorganic compound containing lithium and oxygen (lithium oxide (Li2O) or the like). Alternatively, a material that can be used for the electron-injection layer can be suitably used for the electron-injection buffer layer.

The charge-generation layer preferably includes a layer containing a material having a high electron-transport property. The layer can also be referred to as an electron-relay layer. The electron-relay layer is preferably provided between the charge-generation region and the electron-injection buffer layer. In the case where the charge-generation layer does not include an electron-injection buffer layer, the electron-relay layer is preferably provided between the charge-generation region and the electron-transport layer. The electron-relay layer has a function of inhibiting interaction between the charge-generation region and the electron-injection buffer layer (or the electron-transport layer) and smoothly transferring electrons.

A phthalocyanine-based material such as copper (II) phthalocyanine (abbreviation: CuPc) or a metal complex having a metal-oxygen bond and an aromatic ligand is preferably used for the electron-relay layer.

Note that the charge-generation region, the electron-injection buffer layer, and the electron-relay layer cannot be clearly distinguished from each other in some cases on the basis of the cross-sectional shapes, the characteristics, or the like.

Note that the charge-generation layer may contain a donor material instead of an acceptor material. For example, the charge-generation layer may include a layer containing an electron-transport material and a donor material, which can be used for the electron-injection layer.

When the light-emitting units are stacked, provision of a charge-generation layer between two light-emitting units can inhibit an increase in driving voltage.

This embodiment can be combined with the other embodiments as appropriate. In the case where a plurality of structure examples are described in one embodiment in this specification, the structure examples can be combined as appropriate.

In this embodiment, electronic devices of one embodiment of the present invention will be described.

Electronic devices of this embodiment each include the display device of one embodiment of the present invention in a display portion. The display device of one embodiment of the present invention is highly reliable and can be easily increased in resolution and definition. Thus, the display device of one embodiment of the present invention can be used for a display portion of a variety of electronic devices.

Examples of the electronic devices include electronic devices with a relatively large screen, such as a television device, a desktop or notebook personal computer, a monitor of a computer or the like, digital signage, and a large game machine such as a pachinko machine: a digital camera: a digital video camera: a digital photo frame: a mobile phone: a portable game console: a portable information terminal; and an audio reproducing device.

In particular, the display device of one embodiment of the present invention can have a high resolution, and thus can be suitably used for an electronic device having a relatively small display portion. Examples of such an electronic device include a watch-type or a bracelet-type information terminal device (wearable device), and a wearable device worn on a head, such as a device for VR such as a head-mounted display, a glasses-type device for AR, and a device for MR.

The definition of the display device of one embodiment of the present invention is preferably as high as HD (number of pixels: 1280×720), FHD (number of pixels: 1920×1080), WQHD (number of pixels: 2560×1440), WQXGA (number of pixels: 2560×1600), 4K (number of pixels: 3840×2160), or 8K (number of pixels: 7680×4320). In particular, a definition of 4K. 8K, or higher is preferable. The definition (resolution) of the display device of one embodiment of the present invention is preferably higher than or equal to 100 ppi, further preferably higher than or equal to 300 ppi, still further preferably higher than or equal to 500 ppi, yet still further preferably higher than or equal to 1000 ppi, yet still further preferably higher than or equal to 2000 ppi, yet still further preferably higher than or equal to 3000 ppi, yet still further preferably higher than or equal to 5000 ppi, yet still further preferably higher than or equal to 7000 ppi. With the use of such a display device having one or both of high definition and high resolution, the electronic device can provide higher realistic sensation, sense of depth, and the like in personal use such as portable use and home use. There is no particular limitation on the screen ratio (aspect ratio) of the display device of one embodiment of the present invention. For example, the display device is compatible with a variety of screen ratios such as 1:1 (a square), 4:3, 16:9, and 16:10.

Examples of a wearable device that can be worn on a head are described with reference toFIG.78AtoFIG.78D. These wearable devices have at least one of a function of displaying AR contents, a function of displaying VR contents, a function of displaying SR contents, and a function of displaying MR contents. The electronic device having a function of displaying contents of at least one of AR, VR, SR, MR, and the like enables the user to feel a higher sense of immersion.

An electronic device700A illustrated inFIG.78Aand an electronic device700B illustrated inFIG.78Beach include a pair of display panels751, a pair of housings721, a communication portion (not illustrated), a pair of wearing portions723, a control portion (not illustrated), an image capturing portion (not illustrated), a pair of optical members753, a frame757, and a pair of nose pads758.

The display device of one embodiment of the present invention can be used for the display panel751. Thus, a highly reliable electronic appliance is obtained.

The electronic device700A and the electronic device700B can each project images displayed on the display panels751onto display regions756of the optical members753. Since the optical members753have a light-transmitting property, a user can see images displayed on the display regions, which are superimposed on transmission images seen through the optical members753. Accordingly, the electronic device700A and the electronic device700B are electronic devices capable of AR display.

In the electronic device700A and the electronic device700B, a camera capable of capturing images of the front side may be provided as the image capturing portion. Furthermore, when the electronic device700A and the electronic device700B are provided with an acceleration sensor such as a gyroscope sensor, the orientation of the user's head can be sensed and an image corresponding to the orientation can be displayed on the display regions756.

The communication portion includes a wireless communication device, and a picture signal, for example, can be supplied by the wireless communication device. Instead of or in addition to the wireless communication device, a connector that can be connected to a cable for supplying a video signal and a power supply potential may be provided.

The electronic device700A and the electronic device700B are provided with a battery so that they can be charged wirelessly and/or by wire.

A touch sensor module may be provided in the housing721. The touch sensor module has a function of detecting a touch on the outer surface of the housing721. Detecting a tap operation, a slide operation, or the like by the user with the touch sensor module enables executing various types of processing. For example, processing such as a pause or a restart of a moving image can be executed by a tap operation, and processing such as fast forward and fast rewind can be executed by a slide operation. When the touch sensor module is provided in each of the two housings721, the range of the operation can be increased.

Any of various touch sensors can be applied to the touch sensor module. For example, any of touch sensors of the following types can be used: a capacitive type, a resistive type, an infrared type, an electromagnetic induction type, a surface acoustic wave type, and an optical type. In particular, a capacitive sensor or an optical sensor is preferably used for the touch sensor module.

In the case of using an optical touch sensor, a photoelectric conversion device (also referred to as a photoelectric conversion element) can be used as a light-receiving element. One or both of an inorganic semiconductor and an organic semiconductor can be used for an active layer of the photoelectric conversion device.

An electronic device800A illustrated inFIG.78Cand an electronic device800B illustrated inFIG.78Deach include a pair of display portions820, a housing821, a communication portion822, a pair of wearing portions823, a control portion824, a pair of image capturing portions825, and a pair of lenses832.

A display device of one embodiment of the present invention can be used in the display portions820. Thus, a highly reliable electronic appliance is obtained.

The display portions820are positioned inside the housing821so as to be seen through the lenses832. When the pair of display portions820display different images, three-dimensional display using parallax can be performed.

The electronic device800A and the electronic device800B can be regarded as electronic devices for VR. The user who wears the electronic device800A or the electronic device800B can see images displayed on the display portions820through the lenses832.

The electronic device800A and the electronic device800B preferably include a mechanism for adjusting the lateral positions of the lenses832and the display portions820so that the lenses832and the display portions820are positioned optimally in accordance with the positions of the user's eyes. Moreover, the electronic device800A and the electronic device800B preferably include a mechanism for adjusting focus by changing the distance between the lenses832and the display portions820.

The electronic device800A or the electronic device800B can be mounted on the user's head with the wearing portions823. Note thatFIG.78Cillustrates an example in which the wearing portion823has a shape like a temple (also referred to as a joint or the like) of glasses; however, one embodiment of the present invention is not limited thereto. The wearing portion823can have any shape with which the user can wear the electronic device, for example, a shape of a helmet or a band.

The image capturing portion825has a function of obtaining information on the external environment. Data obtained by the image capturing portion825can be output to the display portion820. An image sensor can be used for the image capturing portion825. Moreover, a plurality of cameras may be provided so as to cover a plurality of fields of view, such as a telescope field of view and a wide field of view.

Although an example where the image capturing portions825are provided is described here, a range sensor capable of measuring a distance from an object (hereinafter also referred to as a sensing portion) just needs to be provided. In other words, the image capturing portion825is one embodiment of the sensing portion. As the sensing portion, an image sensor or a distance image sensor such as LIDAR (Light Detection and Ranging) can be used, for example. By using images obtained by the camera and images obtained by the range image sensor, more information can be obtained and a gesture operation with higher accuracy is possible.

The electronic device800A may include a vibration mechanism that functions as bone-conduction earphones. For example, any one or more of the display portion820, the housing821, and the wearing portion823can employ a structure including the vibration mechanism. Thus, without additionally requiring an audio device such as headphones, earphones, or a speaker, the user can enjoy video and sound only by wearing the electronic device800A.

The electronic device800A and the electronic device800B may each include an input terminal. To the input terminal, a cable for supplying, for example, a video signal from a video output device, power for charging a battery provided in the electronic device, and the like can be 0 connected.

The electronic device of one embodiment of the present invention may have a function of performing wireless communication with earphones750. The earphones750include a communication portion (not illustrated) and has a wireless communication function. The earphones750can receive information (e.g., audio data) from the electronic device with the wireless communication function. For example, the electronic device700A inFIG.78Ahas a function of transmitting information to the earphones750with the wireless communication function. For another example, the electronic device800A illustrated inFIG.78Chas a function of transmitting information to the earphones750with the wireless communication function.

The electronic device may include an earphone portion. The electronic device700B inFIG.78Bincludes earphone portions727. For example, the earphone portion727and the control portion can be connected to each other by wire. Part of a wiring that connects the earphone portion727and the control portion may be positioned inside the housing721or the wearing portion723.

Similarly, the electronic device800B illustrated inFIG.78Dincludes earphone portions827. For example, the earphone portion827and the control portion824can be connected to each other by wire. Part of a wiring that connects the earphone portion827and the control portion824may be positioned inside the housing821or the wearing portion823. Alternatively, the earphone portions827and the wearing portions823may include magnets. This is preferable because the earphone portions827can be fixed to the wearing portions823with magnetic force and thus can be easily housed.

The electronic device may include an audio output terminal to which earphones, headphones, or the like can be connected. The electronic device may include one or both of an audio input terminal and an audio input mechanism. As the audio input mechanism, a sound collecting device such as a microphone can be used, for example. The electronic device may have a function of what is called a headset by including the audio input mechanism.

As described above, both the glasses-type device (e.g., the electronic device700A and the electronic device700B) and the goggles-type device (e.g., the electronic device800A and the electronic device800B) are preferable as the electronic device of one embodiment of the present invention.

The electronic device of one embodiment of the present invention can transmit information to earphones by wire or wirelessly.

An electronic device6500illustrated inFIG.79Ais a portable information terminal that can be used as a smartphone.

The display device of one embodiment of the present invention can be used in the display portion6502. Thus, a highly reliable electronic appliance is obtained.

FIG.79Bis a schematic cross-sectional view including an end portion of the housing6501on the microphone6506side.

The display device6511, the optical member6512, and the touch sensor panel6513are fixed to the protection member6510with an adhesive layer (not illustrated).

Part of the display device6511is folded back in a region outside the display portion6502, and an FPC6515is connected to the part that is folded back. An IC6516is mounted on the FPC6515. The FPC6515is connected to a terminal provided on the printed circuit board6517.

A flexible display of one embodiment of the present invention can be used as the display device6511. Thus, an extremely lightweight electronic device can be achieved. Since the display device6511is extremely thin, the battery6518with high capacity can be mounted without an increase in the thickness of the electronic device. Moreover, part of the display device6511is folded back so that a connection portion with the FPC6515is provided on the back side of a pixel portion, whereby an electronic device with a narrow bezel can be achieved.

FIG.79Cillustrates an example of a television device. In a television device7100, a display portion7000is incorporated in a housing7101. Here, the housing7101is supported by a stand7103.

The display device of one embodiment of the present invention can be used for the display portion7000. Thus, a highly reliable electronic appliance is obtained.

Operation of the television device7100illustrated inFIG.79Ccan be performed with an operation switch provided in the housing7101and a separate remote control7111. Alternatively, the display portion7000may include a touch sensor, and the television device7100may be operated by touch on the display portion7000with a finger or the like. The remote control7111may be provided with a display portion for displaying information output from the remote control7111. With operation keys or a touch panel provided in the remote control7111, channels and volume can be controlled and videos displayed on the display portion7000can be operated.

Note that the television device7100has a structure in which a receiver, a modem, and the like are provided. A general television broadcast can be received with the receiver. When the television device is connected to a communication network by wire or wirelessly via the modem, one-way (from a transmitter to a receiver) or two-way (between a transmitter and a receiver or between receivers, for example) data communication can be performed.

FIG.79Dillustrates an example of a notebook personal computer. A notebook personal computer7200includes a housing7211, a keyboard7212, a pointing device7213, an external connection port7214, and the like. In the housing7211, the display portion7000is incorporated.

The display device of one embodiment of the present invention can be used for the display portion7000. Thus, a highly reliable electronic appliance is obtained.

FIG.79EandFIG.79Fillustrate examples of digital signage.

Digital signage7300illustrated inFIG.79Eincludes a housing7301, the display portion7000, a speaker7303, and the like. The digital signage7300can also include an LED lamp, an operation key (including a power switch or an operation switch), a connection terminal, a variety of sensors, a microphone, and the like.

FIG.79Fis digital signage7400attached to a cylindrical pillar7401. The digital signage7400includes the display portion7000provided along a curved surface of the pillar7401.

The display device of one embodiment of the present invention can be used for the display portion7000illustrated in each ofFIG.79EandFIG.79F. Thus, a highly reliable electronic appliance is obtained.

A larger area of the display portion7000can increase the amount of information that can be provided at a time. The larger display portion7000attracts more attention, so that the effectiveness of the advertisement can be increased, for example.

A touch panel is preferably used in the display portion7000, in which case intuitive operation by a user is possible in addition to display of an image or a moving image on the display portion7000. Moreover, for an application for providing information such as route information or traffic information, usability can be enhanced by intuitive operation.

As illustrated inFIG.79EandFIG.79F, it is preferable that the digital signage7300or the digital signage7400can work with an information terminal7311or an information terminal7411such as a smartphone a user has through wireless communication. For example, information of an advertisement displayed on the display portion7000can be displayed on a screen of the information terminal7311or the information terminal7411. By operation of the information terminal7311or the information terminal7411, display on the display portion7000can be switched.

It is possible to make the digital signage7300or the digital signage7400execute a game with the use of the screen of the information terminal7311or the information terminal7411as an operation means (controller). Thus, an unspecified number of users can join in and enjoy the game concurrently.

The electronic devices illustrated inFIG.80AtoFIG.80Ghave a variety of functions. For example, the electronic devices can have a function of displaying a variety of information (a still image, a moving image, a text image, and the like) on the display portion, a touch panel function, a function of displaying a calendar, date, time, and the like, a function of controlling processing with the use of a variety of software (programs), a wireless communication function, and a function of reading out and processing a program or data stored in a recording medium. Note that the functions of the electronic devices are not limited thereto, and the electronic devices can have a variety of functions. The electronic devices may include a plurality of display portions. In addition, the electronic devices may each include a camera, for example, and have a function of taking a still image or a moving image and storing the taken image in a recording medium (an external recording medium or a recording medium incorporated in the camera), a function of displaying the taken image on the display portion, or the like.

The details of the electronic devices illustrated inFIG.80AtoFIG.80Gare described below:

FIG.80Ais a perspective view illustrating a portable information terminal9101. The portable information terminal9101can be used as a smartphone, for example. Note that the portable information terminal9101may include the speaker9003, the connection terminal9006, the sensor9007, or the like. The portable information terminal9101can display characters and image information on its plurality of surfaces.FIG.80Aillustrates an example where three icons9050are displayed. Furthermore, information9051indicated by dashed rectangles can be displayed on another surface of the display portion9001. Examples of the information9051include notification of reception of an e-mail, an SNS message, an incoming call, or the like, the title and sender of an e-mail, an SNS message, or the like, the date, the time, remaining battery, and the radio field intensity. Alternatively, the icon9050or the like may be displayed at the position where the information9051is displayed.

FIG.80Bis a perspective view illustrating a portable information terminal9102. The portable information terminal9102has a function of displaying information on three or more surfaces of the display portion9001. Here, an example is illustrated in which information9052, information9053, and information9054are displayed on different surfaces. For example, a user can check the information9053displayed in a position that can be observed from above the portable information terminal9102, with the portable information terminal9102put in a breast pocket of his/her clothes. The user can see the display without taking out the portable information terminal9102from the pocket and decide whether to answer the call, for example.

FIG.80Cis a perspective view illustrating a tablet terminal9103. The tablet terminal9103is capable of executing a variety of applications such as mobile phone calls, e-mailing, viewing and editing texts, music reproduction, Internet communication, and a computer game, for example. The tablet terminal9103includes the display portion9001, the camera9002, the microphone9008, and the speaker9003on the front surface of the housing9000: the operation keys9005as buttons for operation on the left side surface of the housing9000; and the connection terminal9006on the bottom surface of the housing9000.

FIG.80Dis a perspective view illustrating a watch-type portable information terminal9200. For example, the portable information terminal9200can be used as a Smartwatch (registered trademark). The display surface of the display portion9001is curved, and display can be performed on the curved display surface. Furthermore, for example, mutual communication between the portable information terminal9200and a headset capable of wireless communication can be performed, and thus hands-free calling is possible. With the connection terminal9006, the portable information terminal9200can perform mutual data transmission with another information terminal and charging. Note that the charging operation may be performed by wireless power feeding.

FIG.80EtoFIG.80Gare perspective views illustrating a foldable portable information terminal9201.FIG.80Eis a perspective view of an opened state of the portable information terminal9201,FIG.80Gis a perspective view of a folded state thereof, andFIG.80Fis a perspective view of a state in the middle of change from one ofFIG.80EandFIG.80Gto the other. The portable information terminal9201is highly portable in the folded state and is highly browsable in the opened state because of a seamless large display region. The display portion9001of the portable information terminal9201is supported by three housings9000joined together by hinges9055. The display portion9001can be folded with a radius of curvature greater than or equal to 0.1 mm and less than or equal to 150 mm, for example.

This embodiment can be combined with the other embodiments as appropriate. In the case where a plurality of structure examples are described in one embodiment in this specification, the structure examples can be combined as appropriate.

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