Organic electroluminescent display device and method for producing same

According to an embodiment of the invention, the organic EL device (100) comprises: an element substrate (20) having a substrate (1) and a plurality of organic EL elements (3) supported by the substrate; a thin film encapsulation structure (10) formed above the plurality of organic EL elements and having at least one compound layered body (10S) constituted by a first inorganic barrier layer (12), an organic barrier layer (14) in contact with the upper surface of the first inorganic barrier layer and having a plurality of solid sections spread out discretely, and a second inorganic barrier layer (16) in contact with the upper surface of the first inorganic barrier layer and the upper surfaces of the plurality of solid sections of the organic barrier layer; an organic planarization layer (42) provided above the thin film encapsulation structure and formed from a photosensitive resin; and a touch sensor layer (50) disposed above the organic planarization layer.

TECHNICAL FIELD

The present invention relates to an organic EL device (e.g., organic EL display device and organic EL illumination device) and a method for producing the same.

BACKGROUND ART

Organic EL (Electroluminescence) display devices start being put into practical use. One feature of an organic EL display device is flexibility thereof. Such an organic EL display device includes, in each of pixels, at least one organic EL element (Organic Light Emitting Diode: OLED) and at least one TFT (Thin Film Transistor) controlling an electric current to be supplied to the at least one OLED. Hereinafter, an organic EL display device will be referred to as an “OLED display device”. Such an OLED display device including a switching element such as a TFT or the like in each of OLEDs is called an “active matrix OLED display device”. A substrate including the TFTs and the OLEDs will be referred to as an “element substrate”.

An OLED (especially, an organic light emitting layer and a cathode electrode material) is easily influenced by moisture to be deteriorated and to cause display unevenness. One technology developed to provide an encapsulation structure that protects the OLED against, moisture while not spoiling the flexibility of the OLED display device is a thin film encapsulation (TFE) technology. According to the thin film encapsulation technology, an inorganic barrier layer and an organic barrier layer are stacked alternately to allow such thin films to provide a sufficient level of water vapor barrier property. From the point of view of the moisture-resistance reliability of the OLED display device, such a thin film encapsulation structure is typically required to have a WVTR (Water Vapor-Transmission Rate) lower than, or equal to, 1×10−4g/m2/day.

A thin film encapsulation structure used in OLED display devices commercially available currently includes an organic barrier layer (polymer barrier layer) having a thickness of about 5 μm to about 20 μm. Such a relatively thick organic barrier layer, also has a role of flattening a surface of the element substrate. However, such a thick organic barrier layer involves a problem of limiting the bendability of the OLED display device.

There is also a problem that the mass-productivity is low. The relatively thick organic barrier layer described above is formed by use of a printing technology such as an inkjet method, a microjet method or the like. By contrast, an inorganic barrier layer is formed by a thin film formation technology in a vacuum atmosphere (e.g., lower than, or equal to, 1 Pa). The formation of the organic barrier layer by use of a printing method is performed in the air or a nitrogen atmosphere, whereas the formation of the inorganic barrier layer is performed in vacuum. Therefore, the element substrate is put into, and out of, a vacuum chamber during the formation of the thin film encapsulation structure, which decreases the mass-productivity.

Under such a situation, as disclosed in, for example, Patent Document No. 1, a film formation device capable of producing an inorganic barrier layer and an organic barrier layer continuously has been developed.

Patent Document No. 2 discloses a thin film encapsulation structure including a first inorganic material layer, a first resin member and a second inorganic material layer provided on the element substrate in this order, with the first inorganic barrier layer being closest to the element substrate. In this thin film encapsulation structure, the first resin member is present locally, more specifically, in the vicinity of a protruding portion of the first inorganic material layer (first inorganic material layer covering the protruding portion). According to Patent Document No. 2, since the first resin member is present locally, more specifically, in the vicinity of the protruding portion, which may not be sufficiently covered with the first inorganic material layer, entrance of moisture or oxygen via the non-covered portion is suppressed. In addition, the first resin member acts as an underlying layer for the second inorganic material layer. Therefore, the second inorganic material layer is properly formed and properly covers a side surface of the first inorganic material layer with an expected thickness. The first resin member is formed as follows. An organic material heated and vaporized to be mist-like is supplied onto an element substrate maintained at a temperature lower than, or equal to, room temperature. The organic material is condensed and put into liquid drops on the substrate. The organic material in the liquid drops moves on the substrate by a capillary action or a surface tension to be present locally, more specifically, at a border between a side surface of the protruding portion of the first inorganic material layer and a surface of the substrate. Then, the organic material is cured to form the first resin member at the border. Patent Document No. 3 also discloses an OLED display device including a similar thin film encapsulation structure. Patent Document No. 4 discloses a film formation device usable to produce an OLED display device.

The thin film encapsulation structure that is described in each of Patent Documents Nos. 2 and 3 and includes an organic barrier layer formed of a resin located locally does not include a thick organic barrier layer. Therefore, the thin film encapsulation structure is considered to improve the bendability of the OLED display device. In addition, since the inorganic barrier layer and the organic barrier layer may be formed continuously, the mass-productivity is also improved.

However, according to the studies made by the present inventors, an organic barrier layer formed by the method described in Patent Document No. 2 or 3 has a problem of not providing a sufficiently high level of moisture-resistance reliability. This problem has been found to be caused because water vapor in the air reaches the inside of an active region on the element substrate (the active region may also be referred to as an “element formation region” or a “display region”) via the organic barrier layer.

In the case where an organic barrier layer is formed by use of a printing method such as an inkjet method or the like, it is possible to form the organic barrier layer only in an active region on the element substrate (the active region may also be referred to as an “element formation region” or a “display region”) but not in a region other than the active region. In this case, along a periphery of the active region (outer to the active region), there is a region where the first inorganic material layer and the second inorganic material layer are in direct contact with each other, and the organic barrier layer is fully enclosed by the first inorganic material layer and the second inorganic material layer and is insulated from the outside of the first inorganic material layer and the second inorganic material layer.

By contrast, according to the method for forming the organic barrier layer described in Patent Document No. 2 or 3, a resin (organic material) is supplied to the entire surface of the element substrate, and the surface tension of the resin, which is in a liquid state, is used to locate the resin locally, more specifically, at the border between the surface of the element substrate and the side surface of the protruding portion on the surface of the element substrate. Therefore, the organic barrier layer may also be formed in a region other than the active region (the region other than the active region may also be referred to as a “peripheral region”), namely, a terminal region where a plurality of terminals are located and a lead wire region where lead wires extending from the active region to the terminal region are formed. Specifically, the resin is present locally, more specifically, at, for example, the border between side surfaces of the lead wires or side surfaces of the terminals and the surface of the substrate. In this case, an end of a portion, of the organic barrier layer, that is formed along the lead wires is not enclosed by the first inorganic barrier layer or the second inorganic barrier layer, but is exposed to the air (ambient atmosphere).

The organic barrier layer is lower in the water vapor barrier property than the inorganic barrier layer. Therefore, the organic barrier layer formed along the lead wires acts as a route that leads the water vapor in the air to the active region.

The conventional thin film encapsulation structure including an organic barrier layer formed of a resin located locally also involves the following problem.

For example, as described in Patent Document No. 5, in an OLED display device having a touch panel function that is used for a smartphone or a tablet terminal, an organic barrier layer in a thin film encapsulation structure is relatively thick and acts as a flattening layer. A touch sensor layer (also referred to as a “touch screen layer”) is provided on a flat surface of the thin film encapsulation structure while an adhesive layer is located between the touch sensor layer and the flat surface. In the case where a thin film encapsulation structure on which the touch sensor layer is provided includes a relatively thin organic barrier layer described in Patent Document No. 2 or 3, the following problem occurs. In the case where a particle (foreign object) is present in the thin film encapsulation structure, the top surface of the thin film encapsulation structure is made non-flat. Therefore, the touch sensor layer is strained, and as a result, the touch panel function may be deteriorated. For example, in a touch sensor of a resistive film system, which has a macroscopic gap between a pair of electrodes, and in a touch sensor of a projected capacitive system, which detects a change in the capacitance between electrodes, a site where such a particle is present may be erroneously detected as a touched position.

In the above, some problems of a thin film encapsulation structure preferably usable for a flexible OLED display device is described. The thin film encapsulation structure is not limited to being used for an OLED display device, and is also usable for other types of organic EL devices such as an organic EL illumination device and the like.

CITATION LIST

Patent Literature

SUMMARY OF INVENTION

Technical Problem

The present invention, made to solve the above-described problems, has an object of providing an organic EL device including a thin film encapsulation structure that includes a relatively thin organic barrier layer, by which the mass-productivity and the moisture-resistance reliability are improved and deterioration of a touch panel function is suppressed, and also providing a method for producing the same.

Solution to Problem

An organic EL device according to an embodiment of the present invention includes an element substrate including a substrate and a plurality of organic EL elements supported by the substrate; a thin film encapsulation structure formed on the plurality of organic EL elements, the thin film encapsulation structure including at least one composite stack body that includes a first inorganic barrier layer, an organic barrier layer including a plurality of solid portions in contact with a top surface of the first inorganic barrier layer and distributed discretely, and a second inorganic barrier layer in contact with the top surface of the first inorganic barrier layer and top surfaces of the plurality of solid portions of the organic barrier layer; an organic flattening layer provided on the thin film encapsulation structure and formed of a photosensitive resin; and a touch sensor layer located on the organic flattening layer. A “solid portion” refers to a portion, of the organic barrier layer, where an organic film (e.g., photocured resin film) is actually present. By contrast, a portion, of the organic barrier layer, where the organic film is absent is referred to as a “non-solid portion”. The non-solid portion enclosed by the solid portion may also be referred to as an “opening”.

In an embodiment, the plurality of solid portions included in the organic barrier layer include a plurality of solid portions each having a recessed surface.

In an embodiment, the organic barrier layer is formed of a photocured resin (obtained by curing a photocurable resin). The photocurable resin is preferably an ultraviolet-curable resin, and an acrylic resin (acrylic monomer (encompassing an acrylic oligomer)) is preferably usable.

In an embodiment, the first and second inorganic barrier layers are each independently an SiNxlayer having a thickness of 200 nm or greater and 1000 nm or less.

In an embodiment, the photosensitive resin is of a negative type.

In an embodiment, the organic flattening layer has a thickness that does not exceed 15 μm. The organic flattening layer has a thickness of, for example, 3 μm or greater.

In an embodiment, the photosensitive resin contains a silicone resin. The photosensitive resin may be an acrylic resin.

In an embodiment, the organic flattening layer has a transmittance of 80% or higher to light having a wavelength of 350 nm.

In an embodiment, the photosensitive resin has an elastic modulus that does not exceed 400 MPa at 0° C.

In an embodiment, the organic EL device further includes an inorganic insulating layer covering the organic flattening layer. The touch sensor layer is formed on the inorganic insulating layer. The inorganic insulating layer is, for example, an SiNxlayer. The SiNxlayer has a thickness of, for example, 200 nm or greater and 0.1000 nm or less.

In an embodiment, the organic flattening layer covers at least the entirety of an active region in which the plurality of organic EL elements are located, and is formed in a range larger than a range of the tough sensor layer.

In an embodiment, the organic flattening layer covers the entirety of the element substrate.

In an embodiment, the organic EL device further includes a driving circuit supported by the substrate, a plurality of terminals located in a peripheral region, and a plurality of lead wires connecting the driving circuit and the plurality of terminals to each other. The thin film encapsulation structure is provided on a portion, of each of the plurality of lead wires, that is closer to the driving circuit, and includes an inorganic barrier layer joint portion where no organic barrier layer is present and the first inorganic barrier layer and the second inorganic barrier layer are in direct contact with each other, the inorganic barrier layer joint portion being provided on the portion of each of the plurality of lead wires. In a cross-section of each of the plurality of lead wires that is taken along a plane parallel to a line width direction thereof, a side surface of the lead wire preferably has a tapering angle smaller than 90 degrees, and a side surface of the first inorganic barrier layer preferably has a tapering angle smaller than 70 degrees. It is preferred that the inorganic barrier layer joint portion has a length of at least 0.01 mm.

A method for producing an organic EL device according to an embodiment of the present invention is a method for producing any one of the above-described organic EL devices. A step of forming the organic flattening layer includes step A of preparing the element substrate on which the thin film encapsulation structure is formed; step B of applying a liquid containing a negative-type photosensitive resin to the element substrate such that the liquid covers at least the thin film encapsulation structure; and step C of irradiating the entirety of the photosensitive resin on the element substrate with light.

In an embodiment, the step B is a step of applying the liquid to only a predetermined region on the element substrate. The step B may be performed by, for example, a known printing method (e.g., an inkjet method and a screen printing method).

A method for producing an organic EL device according to an embodiment of the present invention is a method for producing any one of the above-described organic EL devices. A step of forming the organic flattening layer includes step A of preparing the element substrate on which the thin film encapsulation structure is formed; step B of applying a liquid containing a photosensitive resin to the element substrate such that the liquid covers at least the thin film encapsulation structure; step C of selectively irradiating a portion, of the photosensitive resin, that is in a predetermined region on the element substrate or in a region other than the predetermined region, with light; and step D of putting the photosensitive resin into contact with a developer after the step C. The step B may be a step of applying the liquid containing the photosensitive resin to the entirety of the element substrate. In this case, the method may include a step of connecting an external substrate with the plurality of terminals of the element substrate may be provided before the step B.

In an embodiment of the present invention, a step of forming the at least one composite stack body includes the steps of preparing, in a chamber, the element substrate on which the first inorganic barrier layer is formed; supplying a vapor-like or mist-like photocurable resin into the chamber; condensing the photocurable resin on the first inorganic barrier layer to form a liquid film; irradiating the liquid film formed of the photocurable resin with light to form a photocured resin layer; and partially ashing the photocured resin layer to form the organic barrier layer. The thickness of the liquid film and/or the conditions of ashing may be adjusted to adjust the region in which the photocured resin is to be left and the thickness of the photocured resin.

In an embodiment, the ashing is performed by plasma ashing using, for example, at least one type of gas among N2O, O2and O3.

In an embodiment of the present invention, a step of forming the at least one composite stack body may include a step of forming the organic barrier layer by the method described in Patent Document No. 2 or 3. According to such a method, a photocured resin may be located locally, more specifically, at a border between a side surface of a protruding portion and a flat portion of the first inorganic barrier layer (making a tapering angle of 90 degrees or larger). In a cross-section of each of the plurality of lead wires that is taken along a plane parallel to a line width direction thereof, a side surface of the lead wire preferably has a tapering angle smaller than 30 degrees, and a side surface of the first inorganic barrier layer preferably has a tapering angle smaller than 70 degrees.

Advantageous Effects of Invention

An embodiment of the present invention provides an organic EL device including a thin film encapsulation structure that includes a relatively thin organic barrier layer, by which the mass-productivity and the moisture-resistance reliability are improved and deterioration of a touch panel function is suppressed, and also provides a method for producing the same.

DESCRIPTION OF EMBODIMENTS

Hereinafter, an organic EL device and a method for producing the came according to embodiments of the present invention will be described with reference to the drawings. The embodiments of the present invention are not limited to those described below as examples.

With reference toFIG. 1(a)andFIG. 1(b), a basic structure of an OLED display device100according to an embodiment of the present, invention will be described.FIG. 1(a)is a schematic partial cross-sectional view of an active region of the OLED display device100according to an embodiment of the present invention.FIG. 1(b)is a partial cross-sectional view of a TFE structure10formed on an OLED3.

The OLED display device100includes a plurality of pixels, and each of the pixels includes at least one organic EL element (OLED). Herein, a structure corresponding to one OLED will be described for the sake of simplicity.

As shown inFIG. 1(a), the OLED display device100includes a flexible substrate (hereinafter, may be referred to simply as a “substrate”)1, a circuit (backplane)2formed on the substrate1and including a TFT, the OLED3formed on the circuit2, and the TFE structure10formed on the OLED3. The OLED3is, for example, of a top emission type. An uppermost portion of the OLED3is, for example, a fop electrode or a cap layer (refractive index adjusting layer). The OLED display device100further includes an organic flattening layer42provided on the thin film encapsulation structure10and formed of a photosensitive resin, an inorganic insulating layer44covering the organic flattening layer42, and a touch sensor layer50located on the inorganic insulating layer44. The inorganic insulating layer44may be omitted. An optional polarizing plate4is located on the touch sensor layer50. The polarizing plate4may be located between the TFE structure10and the touch sensor layer50(e.g., between the organic flattening layer42and the touch sensor layer50). The polarizing plate4is a circularly polarizing plate (stack body of a linearly polarizing plate and a λ/4 plate), and plays a role of preventing reflection as is well known. From the point of view of preventing reflection, it is preferred that the polarizing plate4is located on the touch sensor layer50as shown in the figure.

The substrate1is, for example, a polyimide film having a thickness of 15 μm. The circuit2including the TFT has a thickness of, for example, 4 μm. The OLED3has a thickness of, for example, 1 μm. The TFE structure10has a thickness of, for example, 1.5 μm or less. The organic flattening layer42has a thickness of, for, example, 3 μm or greater and 15 μm or less. The inorganic insulating layer44is, for example, an SiNxlayer. The SiNxlayer has a thickness of, for example, 200 nm or greater and 1000 nm or less.

FIG. 1(b)is a partial cross-sectional view of the TFE structure10formed on the OLED3. A first inorganic barrier layer (e.g., SiNxlayer)12is formed immediately on the OLED3, an organic barrier layer (e.g., acrylic resin layer)14is formed on the first inorganic barrier layer12, and a second inorganic barrier layer (e.g., SiNxlayer)16is formed on the organic barrier layer14.

The organic barrier layer14includes a plurality of solid portions that are in contact with a top surface of the first inorganic barrier layer12and distributed discretely. A “solid portion” refers to a portion, of the organic barrier layer14, where an organic film (e.g., photocured resin film) is actually present. By contrast, a portion, of the organic barrier layer14, where the organic film is absent is referred to as a “non-solid portion”. The non-solid portion enclosed by the solid portion may also be referred to as an “opening”. The second inorganic barrier layer16is in contact with the top surface of the first inorganic barrier layer and top surfaces of the plurality of solid portions of the organic barrier layer14. Namely, the second inorganic barrier layer16is in direct contact with the first inorganic barrier layer12in the non-solid portion of the organic barrier layer14.

The TFE structure10is formed to protect the active region (see an active region R1inFIG. 2) of the OLED display device100. The non-solid portion of the organic barrier layer14includes at least a continuous portion provided to enclose the active region R1, and the active region R1is completely enclosed by the portion in which the first inorganic barrier layer12and the second inorganic barrier layer16are in direct contact with each other (hereinafter, such a portion will be referred to as an “inorganic barrier layer joint portion”). Therefore, the solid portions of the organic barrier layer14do not act as a route for moisture.

A stack, structure including the first inorganic barrier layer12and the second inorganic barrier layer16, in contact with the top surface of the first inorganic barrier layer12and the cop surfaces of the plurality of solid portions of the organic barrier layer14, included in the TFE structure10will be referred to as a “composite stack body (10S)”. The TFE structure10includes one composite stack body10S. The TFE structure10is not limited to including one composite stack body10S and may include two or more composite stack bodies10S, or may further include an organic insulating layer and/or an inorganic insulating layer. In the case where the TFE structure10includes the composite stack body10S as an uppermost layer, highly reliable encapsulation is realized.

For example, the first inorganic barrier layer12and the second inorganic barrier layer16are each, for example, an SiNxlayer having a thickness of 400 nm, and the organic barrier layer14is, for example, an acrylic resin layer having a thickness less than 100 nm.

The thicknesses of the first inorganic barrier layer12and the second inorganic barrier layer16are each independently 200 nm or greater and 1500 nm or less, and preferably 1000 run. The thickness of the organic barrier layer14is, for example, 10 nm or greater and less than 500 nm, and preferably 50 nm or greater and less than 300 nm. In the case where the thickness of the organic barrier layer14is less than 50 nm, the effect of the organic barrier layer14may not be fully provided. By contrast, in the case where the thickness of the organic barrier layer14is 500 nm or greater, the effect of the organic barrier layer14is saturated while the production cost is increased. It is preferred that the composite stack body10S has a thickness of 500 nm or greater and 2000 nm or less.

The “thickness” of the organic barrier layer14refers to a thickness of a flat portion thereof. A liquid film of a photocurable resin used to form the organic barrier layer14forms a flat (horizontal) surface. Therefore, in the case where the underlying layer includes a recessed portion, the thickness of the liquid film is increased in such a region. The liquid film forms a curved surface by a surface tension (encompassing a capillary phenomenon). Therefore, the thickness of the liquid film in the vicinity of a protruding portion of the curved surface is increased. Such a locally thick portion may have a thickness exceeding 500 nm.

The thickness of the composite stack body10S is preferably 400 nm or greater and less than 2 μm, and more preferably 400 nm or greater and less than 1.5 μm.

The TFE structure10may include an inorganic insulating layer and/or an organic insulating layer below the composite stack body10S, above the composite stack body10S, or between two composite stack bodies10S. In this case, it is preferred that the inorganic insulating layer has a thickness of, for example, 400 nm or greater and 1500 mm or less. In the case where the thickness of the inorganic insulating layer is less than 400 nm, there are merely relatively small particles having a diameter of, for example, about 0.5 μm and the level of barrier property may be undesirably decreased. In the case where the thickness of the inorganic insulating layer exceeds 1500 nm, the barrier property is saturated, while the stress of the film is increased and as a result, the substrate may be warped.

It is preferred that the organic insulating layer has a thickness of 5 μm or greater and 20 μm or less in the case of being formed by, for example, a common inkjet method. With the inkjet method, it is difficult to form a uniform organic insulating layer having a thickness less than 5 μm. By contrast, in the case where the thickness of the organic insulating layer exceeds 20 μm, the costly material is consumed in a large amount and thus the production cost is increased. Or, in the case where the organic insulating layer is so thick, a component (dam) that keeps the organic material, provided by the inkjet method, at a predetermined position needs to be made high. This complicates the production process.

Now, with reference toFIG. 2throughFIG. 4, the structure of the OLED display device according to an embodiment of the present invention will be described in more detail. In the following, an example in which the TFE structure10includes one composite stack body10S will be described.

First,FIG. 2will be referred to.FIG. 2is a plan view schematically showing the structure of the OLED display device100(the TFE structure10and components below the TFE structure10) according to an embodiment of the present invention.

The circuit2formed on the substrate1includes a plurality of TFTs (not shown), and a plurality of gate bus lines (not shown) and a plurality of source bus lines (not shown) each connected to either one of the plurality of TFTs (not shown). The circuit2may be a known circuit that drives a plurality of the OLEDs3. The plurality of OLEDs3are each connected with either one of the plurality of TFTs included in the circuit2. The OLEDs3may be known OLEDs.

The circuit2further includes a plurality of terminals34located in a peripheral region R2outer to the active region (region enclosed by the dashed line inFIG. 2) R1, where the plurality of OLEDs3are located, and also includes a plurality of lead wires32each connecting either one of the plurality of terminals34and either one of the plurality of gate bus lines or either one of the plurality of source bus lines to each other. The entirety of the circuit2including the plurality of TFTs, the plurality of gate bus lines, the plurality of source bus lines, the plurality of lead wires32and the plurality of terminals34may be referred to as a “driving circuit layer2”. A portion, of the driving circuit layer2, that is formed in the active region R1will be referred to as a “driving circuit layer2A”.

InFIG. 2and the like, only the lead wires32and/or the terminals34may be shown as components of the driving circuit layer2. Nonetheless, the driving circuit-layer2includes a conductive layer including the lead wires32and the terminals34and further includes at least one conductive layer, at least one insulating layer, and at least one semiconductor layer. The structure of the conductive layers, the insulating layer and the semiconductor layer included in the driving circuit layer2may be changed in accordance with the structure of the TFT shown in, for example,FIG. 7(a)andFIG. 7(b)as an example. An insulating film (base coat) may be formed on the substrate1as an underlying layer for the driving circuit layer2.

The TFE structure10(composite stack body10S) is formed to protect the active region R1. The first inorganic barrier layer12and the second inorganic barrier layer16are each, for example, an SiNxlayer, and are selectively formed only in a predetermined region, by plasma CVD by use of a mask, so as to cover the active region R1. In this example, the first inorganic barrier layer12and the second inorganic barrier layer16are independently and selectively formed on the active region R1and portions, of the plurality of lead wires32, that are closer to the active region R1. From the point of view of reliability, it is preferred that the second inorganic barrier layer16is formed in the same region as that of the first inorganic barrier layer12(formed such that the second inorganic barrier layer16and the first inorganic barrier layer12have matching outer edges) or is formed so as to cover the entirety of the first inorganic barrier layer12. The active region R1is enclosed by the inorganic barrier layer joint portion, where the first inorganic barrier layer12and the second inorganic barrier layer16are in direct contact with each other.

The organic barrier layer14may be formed by, for example, the method described in Patent Document No. 2 or 3 mentioned above. For example, in a chamber, a vapor-like or mist-like organic material (e.g., acrylic monomer) is supplied onto an element substrate maintained at a temperature lower than, or equal to, room temperature and is condensed on the element substrate. The organic material put into a liquid state is located locally, more specifically, at a border between a side surface of a protruding portion of, and a flat portion of, the first inorganic barrier layer12by a capillary action or a surface tension of the organic material. Then, the organic material is irradiated with, for example, ultraviolet rays to form a solid portion of the organic barrier layer (e.g., acrylic resin layer)14at the above-mentioned border in the vicinity of the protruding portion. The organic barrier layer14formed by this method does not substantially include the solid portion on the flat portion. Regarding the method for forming the organic barrier layer, the disclosures of Patent Documents Nos. 2 and 3 are incorporated herein by reference.

Alternatively, as described below, the organic barrier layer14may be formed by adjusting an initial thickness of the resin layer to be formed by use of a film formation device200(e.g., to less than 100 nm) and/or by performing ashing on the resin layer once formed. The ashing may be performed by plasma ashing using, for example, at least one type of gas among N2O, O2and O3.

Now,FIG. 3(a)andFIG. 3(b)will be referred to.FIG. 3(a)is a plan view schematically showing a structure of an OLED display device100A (the TFE structure and components above the TFE structure) according to an embodiment of the present invention.FIG. 3(b)is a plan view schematically showing a structure of an OLED display device100B (the TFE structure and components above the TFE structure) according to an embodiment of the present invention.

The OLED display device100A shown inFIG. 3(a)includes an organic flattening layer42A formed of a photosensitive resin and provided on the TFE structure10and also includes the touch sensor layer50located on the organic flattening layer42A. The OLED display device100A may further include an inorganic insulating layer (inorganic insulating layer44inFIG. 1) provided between the organic flattening layer42A and the touch sensor layer50. The organic flattening layer42A is formed only in a predetermined region on the element substrate, and is formed to expose the terminals34and portions, of the lead wires32, that are in the vicinity of the terminals34. It is sufficient that the organic flattening layer42A is formed to cover at least the entirety of the TFE structure10. It is preferred that the organic flattening layer42A covers at least the entirety of the active region R1and is formed in a range larger than that of the touch sensor layer50.

The organic flattening layer42A may be formed, for example, as follows.

A liquid containing a negative-type photosensitive resin is applied only to a predetermined region on the element substrate, on which the TFE structure10is formed. Then, the photosensitive resin on the element substrate is entirely irradiated with light. When necessary, the photosensitive resin on the element substrate is heated (prebaked) before being irradiated with the light to remove a solvent. After being irradiated with the light, the photosensitive resin on the element substrate may be, for example, heated to be further cured. The step of providing the liquid containing the photosensitive resin may be performed by, for example, a known printing method (e.g., an inkjet method and a screen printing method). Such a method does not require a photomask and does not require the post exposure photosensitive resin to be developed.

Alternatively, a liquid containing a negative-type photosensitive resin is applied to the entirety of the element substrate, on which the TFE structure10is formed, and then a portion, of the photosensitive resin, that is present in a predetermined region on the element substrate is selectively irradiated with light. Still alternatively, a liquid containing a positive-type photosensitive resin is applied to the entirety of the element substrate, on which the TFE structure10is formed, and then a portion, of the photosensitive resin, that is present in a region other than the predetermined region on the element substrate is selectively irradiated with light. Then, the photosensitive resin is put into contact with a developer to be developed. Thus, the organic flattening layer42A is formed in only the predetermined region.

The OLED display device100B shown inFIG. 3(b)includes an organic flattening layer42B formed of a photosensitive resin and provided on the TFE structure10and also includes the touch sensor layer50located on the organic flattening layer42B. Unlike in the OLED display device100A, in the OLED display device100B, the organic flattening layer42B covers the entirety of the element substrate. The OLED display device100B may further include an inorganic insulating layer (inorganic insulating layer44inFIG. 1) provided between the organic flattening layer42B and the touch sensor layer50.

The organic flattening layer42B may be formed, for example, as follows.

A liquid containing a negative-type or positive-type photosensitive resin is applied to the entirety of the element substrate, on which the TFE structure10is formed, and is exposed to light by use of a photomask and developed. Thus, the organic flattening layer42B, which has openings42aexposing the terminals34, is formed. The terminals34may be connected with an external substrate in advance. In this case, there is no need to form the openings42a, and thus the photomask does not need to be used.

It is preferred that the organic flattening layers42A and42B each have a thickness not exceeding 15 μm. In the case where the thickness of each of the organic flattening layers42A and42B exceeds 15 μm, the bendability thereof may be declined. From the point of view of the flattening function in the case where there is a particle, it is preferred that the thickness of each of the organic-flattening layers42A and42B is, for example, 3 μm or greater.

It is preferred that the photosensitive resin contains, for example, a silicone resin (herein, this term is used in a wide sense and encompasses silicone rubber and silicone elastomer). An organic flattening layer formed of a silicone resin has a transmittance of 80% or higher to light having a wavelength of 350 nm. An acrylic resin may foe used instead of the silicone resin. An organic flattening layer formed of an acrylic resin has a high transmittance to visible light. However, in order to realize a transmittance of 80% or higher to light having a wavelength of 350 nm, it is preferred to use a silicone resin. The silicone resin may be, for example, KER-2500 produced by Shin-Etsu Chemical Co., Ltd.

From the point of view of the flexibility (bendability) of the OLED display device, it is preferred that the photosensitive resin has an elastic modulus not exceeding 400 MPa at 0° C. For example, in an evaluation performed by use of a U-shape folding tester produced by Yuasa System Co., Ltd., an organic flattening layer formed of such a photosensitive resin may withstand being folded 10,000 times. Specifically, an organic flattening layer formed of such a photosensitive resin is folded at 25° C. into a U-shape such that the folded portion has a radius of 5 mm, and is subjected to a folding operation 10,000 times at an operating frequency of 1 Hz. Even after this, no crack is recognized visually or by an observation with an optical microscope. In a WVTR evaluation performed by use of Ca (calcium), a value in the order of 10−5g/m2·day is obtained. An organic flattening layer formed of such a photosensitive resin also has an effect of alleviating application of an external force, applied to the OLED display device, onto the OLED layer.

As described above, the TFE structure10has a high level of barrier property. Therefore, a photosensitive resin may be applied and subjected to an exposure step and a development step on an element substrate on which the TFE structure10is formed. The OLED layer is easily deteriorated upon contacting a chemical agent. Therefore, in the case where the level of barrier property of the TFE structure10is low, the OLED layer is deteriorated in the development step.

Now,FIG. 4(a)throughFIG. 4(d)will be referred to.FIG. 4(a)throughFIG. 4(c)are schematic cross-sectional views of the OLED display device100A shown inFIG. 3(a).FIG. 4(a)is a cross-sectional view taken along line4A-4A′ inFIG. 3(a),FIG. 4(b)is a cross-sectional view taken along line4B-4B′ inFIG. 3(a), andFIG. 4(c)is a cross-sectional view taken along line4C-4C′ inFIG. 3(a).FIG. 4(d)is a cross-sectional view of an OLED display device100C in a comparative example, and corresponds to the cross-sectional view taken along line4B-4B′ inFIG. 3(a).

FIG. 4(a)is a cross-sectional view taken along line4A-4A′ inFIG. 3(a), and shows a portion including a particle P. The particle P is a microscopic dust particle generated during the production of the OLED display device, and is, for example, a microscopic piece of broken glass, a metal particle or an organic particle. Such a particle is generated especially easily in the case where mask vapor deposition is used.

As shown inFIG. 4(a), the organic barrier layer (solid portion)14may be formed only in the vicinity of the particle P. A reason for this is that the acrylic monomer supplied after the first inorganic barrier layer12is formed is condensed and present locally, more specifically, in the vicinity of a surface of a first inorganic barrier layer12aon the particle P (the surface has a tapering angle θ of 90 degrees or larger). The opening (non-solid portion) of the organic barrier layer14is on the flat portion of the first inorganic barrier layer12.

In the case where the particle (having a diameter of, for example, 1 μm or longer) P is present, a crack (defect)12cmay be formed in the first inorganic barrier layer12. This is considered to be caused by impingement of the SiNxlayer12agrowing from a surface of the particle P and an SiN layer12bgrowing from a flat portion of a surface of the OLED3. In the case where such a crack12cis present, the level of barrier property of the TFE structure10is decreased.

In the TFE structure10in the OLED display device100, as shown inFIG. 4(a), the organic barrier layer14is formed to fill the crack12cof the first inorganic barrier layer12, and a surface of the organic barrier layer14(recessed surface) couples the surface of the first inorganic barrier layer12aon the particle P and a surface of the first inorganic barrier layer12bon the flat portion of the OLED3to each other continuously and smoothly. The organic barrier layer14is formed by curing a photocurable resin in a liquid state as described below, and therefore, has a recessed surface formed by a surface tension. In this state, the photocurable resin exhibits a high level of wettability to the first inorganic barrier layer12. If the level of wettability of the photocurable resin to the first inorganic barrier layer12is low, the surface of the organic barrier layer14may protrude, instead of being recessed.

The organic barrier layer (solid portion)14has such a recessed surface. Therefore, the second inorganic barrier layer16, which is formed on the first inorganic barrier layer12aon the particle P and also on the organic carrier layer14, is a fine film with no defect. As can be seen, even if the particle P is present, the organic barrier layer14keeps high the level of barrier property of the TFE structure10(composite stack body10S).

The organic barrier layer (solid portion)14, which is relatively soft, is present in the vicinity of the particle P, and the second inorganic barrier layer16is present continuously on the particle P. Therefore, even if the composite stack body10S is bent, generation of cracks in the composite stack body10S from the particle P is suppressed. Thus, the decrease in the level of barrier property by the bending is suppressed, and as a result, the composite stack body IDS has a high resistance against bending.

As shown inFIG. 4(b), in a region close to the active region R1(cross-section taken along line4B-4B′ inFIG. 3(a)), the TFE structure10and the organic flattening layer42A are formed on the lead wires32.

As shown inFIG. 4(c), the terminals34are exposed and are used to be electrically connected with an external circuit (e.g., FPC (Flexible Printed Circuits)).

In a region including the portion shown inFIG. 4(b), the organic barrier layer (solid portion) may be formed during the formation of the organic barrier layer14of the TFE structure10. For example, the OLED display device100C in the comparative example shown inFIG. 4(d)includes a TFE structure10C. In the TFE structure10C, in a cross-section of each of the lead wires32that is taken along a plane parallel to a line width direction thereof, a side surface of the lead wire32has a tapering angle θ of 90 degrees or larger. In such a case, an organic barrier layer14C may be formed on the side surface of the lead wire32. By contrast, in the OLED display device100A according to an embodiment, the tapering angle θ of the side surface of the cross-section of each of the lead wires32and the terminals34is smaller than 90 degrees, and thus the photocurable resin is not located locally. Therefore, the organic barrier layer (solid portion) is not formed on the side surface of any of the lead wires32or any of the terminals34.

Assuming that the method for forming the organic barrier layer described in Patent Document No. 2 or 3 is used in the case where the tapering angle of the side surface is 90 degrees or larger, a vapor-like or mist-like organic-material (e.g., acrylic monomer) is condensed, and thus the organic barrier layer (solid portion) is formed, along a border between the side surface and the flat surface (making an angle of 90 degrees or smaller). When this occurs, for example, the organic barrier layer (solid portion) formed along the lead wire acts as a route that guides water vapor in the air to the active region.

In the OLED display device100A in an embodiment according to the present invention shown inFIG. 4(b), the tapering angles of the side surfaces of the lead wires32and the first inorganic barrier layer12are ail smaller than 90 degrees. Thus, the organic barrier layer14is not formed along these side surfaces. Therefore, moisture in the air does not reach the inside of the active region R1via the organic barrier layer (solid portion)14, and thus the OLED display device100A may have a high level of moisture-resistant reliability. In this example, the tapering angle of the lead wire32is smaller than 90 degrees. It is sufficient that the side surface, of the first inorganic barrier layer12, that forms a surface immediately below the inorganic barrier layer14has a tapering angle smaller than 90 degrees.

In the case where the tapering angle of the side surface is in the range of 70 degrees or larger and smaller than 90 degrees, the organic barrier layer (solid portion)14may be formed along the side surface. Needless to say, the resin present locally, namely, along the inclining side surface, is removed by ashing. However, the ashing is time-consuming. For example, the ashing needs to be performed for a long time even after the resin formed on the flat, surface is removed. In addition, there may be a problem that as a result of the organic barrier layer (solid portion) formed in the vicinity of the particle P being excessively ashed (removed), the effect of the formation of the organic barrier layer is not fully provided. In order to suppress or prevent this problem, the tapering angle θ of the first inorganic barrier layer12is preferably smaller than 70 degrees, and more preferably 60 degrees or smaller.

The touch sensor layer50included in the OLED display device100according to an embodiment of the present invention may be a known touch sensor layer, for example, a touch sensor of a resistive film system or of a projected capacitive system. With reference toFIG. 5andFIG. 6, structures of a touch sensor layer50A and a touch sensor layer SOB preferably usable for the OLED display device100will, be described.

FIG. 5(a)is a schematic plan view of the touch sensor layer50A, andFIG. 5(b)is a cross-sectional view of the touch sensor layer50A. The touch sensor layer50A is formed on the inorganic insulating layer44formed on the organic flattening layer42.

The touch sensor layer50A includes a plurality of X electrodes52A extending in an X direction and a plurality of Y electrodes54A extending in a Y direction perpendicular to the X direction. The X electrodes52A and the Y electrodes54A are both formed of a metal mesh. A minimum unit of the metal mesh is, for example, a square having a size of 35 μm×35 μm. A plurality of such squares are assembled to form a square unit electrode having a size of, for example, 3 mm×3 mm. Such unit electrodes are connected it; the X direction or the Y direction by wires. At a portion where the wires cross each other, the wires are insulated from each other by, for example, an inorganic insulating layer (SiNxlayer) (not shown). The metal mesh has, for example, a stack structure of a Ti layer and an Al layer, or a stack structure of Ti layer/Al layer/Ti layer.

FIG. 6(a)is a schematic plan view of the touch sensor layer SOB, andFIG. 6(b)is a cross-sectional view of the touch sensor layer SOB. The touch sensor layer SOB is formed on the inorganic insulating layer44formed on the organic flattening layer42. X electrodes52B and Y electrodes54B included in the touch sensor layer SOB are each formed of a transparent conductive layer (e.g., ITO layer), and are insulated from each other by an inorganic insulating layer (e.g., SiNxlayer). From the point of view of light transmittance, the touch sensor layer50A is more advantageous.

In order to produce the flexible OLED display device100, a polyimide film, for example, is formed on a support substrate (e.g., glass substrate), and the polyimide film on the support substrate is used as the substrate1. An OLED display device including the touch sensor layer50A or SOB described herein as an example may be obtained by peeling off the polyimide film from the support substrate after the touch sensor layer50A or SOB is formed.

Now, with reference toFIG. 7andFIG. 8, an example of TFT usable for the OLED display device100, and an example of; lead wires and terminals formed by use of a gate metal layer and a source metal layer used to form the TFT, will be described.

For a medium- or small-sized high-definition OLED display device, a low temperature polycrystalline silicon (hereinafter, referred to simply as “LTPS”) TFT or an oxide TFT (e.g., four-component-based (In—Ga—Zn—O-based) oxide TFT containing In (indium), Ga (gallium), Zn (zinc) and O (oxygen)) having a high mobility is preferably used. Structures of, and methods for producing, the LTPS-TFT and the in-Ga—Zn—O-based TFT are well known and will be described below merely briefly.

FIG. 7(a)is a schematic cross-sectional view of an LTPS-TFT2pT. The TFT2pT may be included in the circuit2of the OLED display device100. The LTPS-TFT2pT is a top gate-type TFT.

The TFT2pT is formed on a base coat2pp on the substrate (e.g., polyimide film)1. Although not described above, it is preferred that a base coat formed of an inorganic insulating material is formed on the substrate1.

The TFT2pT includes a polycrystalline silicon layer2pse formed on the base coat2pp, a gate insulating layer2pgi formed on the polycrystalline silicon layer2pse, a gate electrode2pg formed on the gate insulating layer2pgi, an interlayer insulating layer2pi formed on the gate electrode2pg, and a source electrode2pss and a drain electrode2psd formed on the interlayer insulating layer2pi. The source electrode2pss and the drain electrode2psd are respectively connected with a source region and a drain region of the polycrystalline silicon layer2pse in contact holes formed in the interlayer insulating layer2pi and the gate insulating layer2pgi.

The gate electrode2pg is included in a gate metal layer including the gate bus lines, and the source electrode2pss and the drain electrode2psd are included in a source metal layer including the source bus lines. The gate metal layer and the source metal layer are used to form lead wires and terminals (described below with reference toFIG. 8).

The TFT2pT is formed, for example, as follows.

As the substrate1, a polyimide film having a thickness of 15 μm, for example, is prepared.

The a-Si film is subjected to dehydrogenation (e.g., annealed at 450° C. for 180 minutes).

The a-Si film is polycrystalline-siliconized by excimer laser annealing (ELA).

The a-Si film is patterned by a photolithography step to form an active layer (semiconductor island).

A gate insulating film (SiO2film: 50 nm) is formed by plasma CVD.

A channel region of the active layer is doped with (B+).

The gate metal layer (Mo: 250 nm) is formed by sputtering and patterned by a photolithography step (including a dry etching step) (to form the gate electrode2pg, the gate bus lines, and the like).

A source region and a drain region of the active layer, are doped with (P+).

Activation annealing (e.g., annealing at 450° C. for 45 minutes) is performed. As a result, the polycrystalline silicon layer2pse is formed.

The contact holes are formed in the gate insulating film and the interlayer insulating film by dry etching. As a result, the interlayer insulating layer2pi and the gate insulating layer2pgi are formed.

The source metal layer (Ti film: 100 nm/Al film: 300 nm/Ti film: 30 nm) is formed by sputtering and patterned by a photolithography step (including a dry etching step) (to form the source electrode2pss, the drain electrode2psd, the source bus lines, and the like).

FIG. 7(b)is a schematic cross-sectional view of an In—Ga—Zn—O-based TFT2oT. The TFT2oT may be included in the circuit2of the OLED display device100A. The TFT2oT is a bottom gate-type TFT.

The TFT2oT is formed on a base coat2op on the substrate1(e.g., polyimide film). The TFT2oT includes a gate electrode2og formed on the base coat2op, a gate insulating layer2ogi formed on the gate electrode2og, an oxide semiconductor layer2ose formed on the gate insulating layer2ogi, and a source electrode2oss and a drain electrode2osd respectively formed on a source region and a drain region of the oxide semiconductor layer2ose. The source electrode2oss and the drain electrode2osd are covered with an interlayer insulating layer2oi.

The gate electrode2og is included in a gate metal layer including the gate bus lines, and the source electrode2oss and the drain electrode2osd are included in a source metal layer including the source bus lines. The gate metal layer and the source metal layer are used to form lead wires and terminals, and thus the TFT2oT may have a structure described below with reference toFIG. 8.

The TFT2oT is formed, for example, as follows.

As the substrate1, a polyimide film having a thickness of 15 μm, for example, is prepared.

The gate metal layer (Co film: 300 nm/Ti film: 30 nm (top layer/bottom layer)) is formed by sputtering and patterned by a photolithography step (including a dry etching step) (to form the gate electrode2og, the gate bus lines, and the like).

An oxide semiconductor film (In—Ga—Z—O-based semiconductor film: 100 nm) is formed by sputtering and patterned by a photolithography step (including a wet etching step) to form an active layer (semiconductor island).

The source metal layer (Ti film: 100 nm/Al film: 300 nm/Ti film: 30 nm (top layer/middle layer/bottom layer)) is formed by sputtering and patterned by a photolithography step (including a dry etching step) (to form the source electrode2oss, the drain electrode2osd, the source bus lines, and the like).

Activation annealing (e.g., annealing at 300° C. for 120 minutes) is performed. As a result, the oxide semiconductor layer2ose is formed.

Now, with reference toFIG. 8(a)andFIG. 8(b), a structure of another OLED display device according to an embodiment will be described. The circuit (backplane)2of this OLED display device includes the TFT2pT shown inFIG. 7(a)or the TFT2oT shown inFIG. 7(b). The gate metal layer and the source metal layer used to form the TFT2pT or the TFT2oT are used to form a lead wire32A and a terminal34A.FIG. 8(a)andFIG. 8(b)respectively correspond toFIG. 4(b)andFIG. 4(c). Components corresponding to those inFIG. 4(b)andFIG. 4(c)will be represented by the identical reference signs thereto provided with letter “A” at the end. The TFE structure10A shown inFIG. 8(a)is covered with an organic flattening layer (not shown). A base coat2pinFIG. 8(a)andFIG. 8(b)corresponds to the base coat2pp inFIG. 7(a)and the base coat2op inFIG. 7(b). A gate insulating layer2giinFIG. 8(a)andFIG. 8(b)corresponds to the gate insulating layer2pgi inFIG. 7(a)and the gate insulating layer2ogi inFIG. 7(b). An interlayer insulating layer2iinFIG. 8(a)andFIG. 8(b)corresponds to the interlayer insulating layer2pi inFIG. 7(a)and the interlayer insulating layer2oi inFIG. 7(b).

As shown inFIG. 8(a)andFIG. 8(b), a gate metal layer2gand a source metal layer2sare formed on the base coat2p, which is formed on the substrate1. Although not shown inFIG. 4, it is preferred that the base coat2pformed of an inorganic insulating material is formed on the substrate1.

As shown inFIG. 8(a)andFIG. 8(b), the lead wire32A and the terminal34A are each formed as a stack body of the gate metal layer2gand the source metal layer2s. A portion of the lead wire32A and a portion of the terminal34A that are formed of the gate metal layer2ghave, for example, the same cross-sectional shape as that of the gate bus lines. A portion of the lead wire32A and a portion of the terminal34A that are formed of the source metal layer2shave, for example, the same cross-sectional shape as that of the source bus lines. In the case of, for example, a 5.7-type display device of 500 ppi, the portion formed of the gate metal layer2ghas a line width of, for example, 10 μm, and a distance between two adjacent such lines is 16 μm (L/S=10/16). The portion formed of the source metal layer2shas a line width of, for example, 16 μm, and a distance between two adjacent such lines is 10 μm (L/S=16/10). These portions each have a tapering angle θ smaller than 90 degrees, preferably smaller than 70 degrees, and more preferably 60 degrees or smaller.

Now, with reference toFIG. 9(a)andFIG. 9(b), a film formation device200usable to form an organic barrier-layer, and a film formation method using the same will be described.FIG. 9(a)andFIG. 9(b)schematically show a structure of the film formation device200.FIG. 9(a)shows a state of the film formation device200in a step of, in a chamber having a vapor-like or mist-like photocurable resin located therein, condensing the photocurable resin on the first inorganic barrier layer.FIG. 9(b)shows a state of the film formation device200in a step of irradiating the photocurable resin with light to which the photocurable resin is sensitive and thus curing the photocurable resin.

The film formation device200includes a chamber210and a partition wall234dividing an inner space of the chamber210into two spaces. In one of the spaces, in the chamber210, demarcated by the partition wall234, a stage212and a shower plate220are located. In the other space demarcated by the partition wall234, an ultraviolet irradiation device230is located. The inner space of the chamber210is controlled to have a predetermined pressure (vacuum degree) and a predetermined temperature. The stage212has a top surface that receives an element substrate20including the plurality of the OLEDs3, on which the first inorganic barrier layer is formed. The top surface may be cooled down to, for example, −20° C.

The shower plate220is located to have a gap224between the shower plate220and the partition wall234. The shower plate220includes a plurality of through-holes222. The gap224may have a size of, for example, 100 mm or longer and 1000 mm or shorter in a vertical direction. An acrylic monomer (vapor-like or mist-like) supplied to the gap224is supplied, via the plurality of through-holes222of the shower plate220, to one of the spaces of the chamber210in which the stage212is located. When necessary, the acrylic monomer is heated. A vapor-like or mist-like acrylic monomer26pis attached to, or contacts, the first inorganic barrier layer on the element substrate20. An acrylic monomer26is supplied from a container202into the chamber210at a predetermined flow rate. The container202is supplied with the acrylic monomer26via a pipe206and is also supplied with nitrogen gas front a pipe204. The flow rate of the acrylic monomer supplied to the container202is controlled by a mass flow controller208. A material supply device includes the shower plate220, the container202, the pipes204and206, the mass flow controller208and the like.

The ultraviolet irradiation device230includes an ultraviolet light source and an optional optical element. The ultraviolet light source may be, for example, an ultraviolet lamp (e.g., mercury lamp (encompassing a high-pressure lamp and a super-high pressure lamp), a mercury-xenon lamp or a metal halide lamp). Alternatively, the ultraviolet light source may be an ultraviolet light emitting semiconductor-element such as an ultraviolet LED, an ultraviolet semiconductor laser or the like. The optical element encompasses, for example, a reflective mirror, a prism, a lens, an optical fiber, a diffractive element, a spatial modulation element, and a hologram. A plurality of ultraviolet light sources may be used in the case where the ultraviolet light sources are of a certain type or a certain size.

The ultraviolet irradiation device230emits light having a predetermined wavelength and a predetermined intensity toward the top surface of the stage212when being located at a predetermined position. It is preferred that the partition wall234and the shower plate220are formed of a material having a high transmittance to ultraviolet rays, for example, quartz.

The organic barrier layer14may be formed, for example, as follows by use of the film formation device200. In this example, an acrylic monomer is used as the photocurable resin.

The acrylic monomer26pis supplied into the chamber210. The element substrate20has been cooled to, for example, −15° C. on the stage212. The acrylic monomer26pis condensed on the first inorganic barrier layer12on the element substrate20. The conditions in this step may be controlled such that the liquid-state acrylic monomer is present locally, more specifically, only in the vicinity of the protruding portion of the first inorganic barrier layer12. Alternatively, the conditions may be controlled such that the acrylic monomer condensed on the first inorganic barrier layer12forms a liquid film.

The viscosity and/or the surface tension of the photocurable resin in the liquid state may be adjusted to control the thickness of the liquid film or the shape of the portion of the liquid film that is to be in contact with the protruding portion of the first inorganic barrier layer12(namely, the shape of the recessed portion). For example, the viscosity and the surface tension depend on the temperature. Therefore, the temperature of the element substrate may be adjusted to control the viscosity and the surface tension. For example, the size of the solid portion that is present on the flat portion may be controlled by the shape of a portion, of the liquid film, that is to be in contact with the protruding portion of the first inorganic barrier layer12(namely, the shape of the recessed portion) and by the conditions of ashing to be performed in a later step.

Next, the ultraviolet irradiation device230is used to, typically, irradiate the entirety of a top surface of the element substrate20with ultraviolet rays232to cure the acrylic monomer on the first inorganic barrier layer12. As an ultraviolet light source, for example, a high-pressure mercury lamp that provides light having a main peak wavelength of 365 nm is used. The ultraviolet rays are directed at an intensity of, for example, 12 mW/cm2for about 10 seconds.

The organic barrier layer14formed of an acrylic-resin is formed in this manner. The tact time of the step of forming the organic barrier layer14is shorter than, for example, about 30 seconds. Thus, the mass-productivity is very high.

Alternatively, after the photocurable resin in the liquid state is cured and ashing is performed, the organic barrier layer14may be formed only in the vicinity of the protruding portion. Even in the case where the organic barrier layer14is formed by curing the photocurable resin present locally, ashing may be performed. The ashing improves the adhesiveness between the organic barrier layer14and the second inorganic barrier layer16. Namely, the ashing may be used to modify (make hydrophilic) the surface of the organic barrier layer14, as well as to remove an extra portion of the organic barrier layer once formed.

The ashing may be performed by use of a known plasma ashing device, a known photoexcitation ashing device, or a known UV ozone ashing device. For example, plasma ashing using at least one type of gas among N2O, O2and O3, or a combination of such plasma ashing and ultraviolet irradiation, may be performed. In the case where an SiN film is formed by CVD as each of the first inorganic barrier layer12and the second inorganic barrier layer16, N2O is used as a material gas. Therefore, use of N2O for the ashing provides an advantage that the device is simplified.

In the case where the ashing is performed, the surface of the organic barrier layer14is oxidized and thus is modified to be hydrophilic. In addition, the surface of the organic barrier layer14is shaved almost uniformly, and extremely tiny convexed and concaved portions are formed, which increases the surface area size. The effect of increasing the surface area size provided by the ashing is greater for the surface of the organic barrier layer14than for the first inorganic barrier layer12formed of an inorganic material. Since the surface of the organic barrier layer14is modified to be hydrophilic and the surface area size of the surface is increased, the adhesiveness of the organic barrier layer14with the second inorganic barrier layer16is improved.

After the above, the resultant body is transported to a CVD chamber in order to form the second inorganic barrier layer16. The second inorganic barrier layer16is formed under, for example, the same conditions as those for the first inorganic barrier layer12. The second inorganic barrier layer16is formed in the region where the first inorganic barrier layer12is formed. Therefore, the inorganic barrier layer joint portion, where the first inorganic barrier layer12and the second inorganic barrier layer16are in direct contact with each other, is formed in the non-solid portion of the organic barrier layer14. For this reason, as described above, water vapor in the air is suppressed or prevented from reaching the inside of the active region via the organic barrier layer.

The first inorganic barrier layer12and the second inorganic barrier layer16are formed, for example, as follows. An inorganic barrier layer having a thickness of 400 nm may be formed by plasma CVD using SiH4gas and N2O gas, at a film formation rate of 400 nm/min, in a state where, for example, the temperature of the substrate on which the inorganic barrier layer is to be formed (the temperature of the OLED3) is controlled to be 80° C. or lower. The inorganic barrier layer thus formed has a refractive index of 1.84 and a transmittance of 90% to visible light having a wavelength of 400 nm (thickness: 400 nm). The film stress has an absolute value of 50 MPa.

The inorganic barrier layer may be an SiO2layer, an SiOxNy(x>y) layer, an SiNxOy(x>y) layer, an Al2O3layer or the like as well as an SiNzlayer. A photocurable resin contains, for example, a vinyl croup-containing monomer. Among vinyl group-containing monomers, an acrylic monomer is preferably used. A photoinitiator may be incorporated into the acrylic monomer when necessary. As the acrylic monomer, any of various known acrylic monomers is usable. A plurality of acrylic monomers may be mixed together. For example, a two-functional monomer and a monomer including three or more functional groups may be mixed together. An oligomer may be mixed. As the photocurable resin, an ultraviolet-curable silicone resin may be used. A silicone resin (encompassing silicone rubber j is highly transmissive to visible light and highly resistant against climate, and is not easily yellowed even after, being used for a long period of time. A photocurable resin that is cured by being irradiated with visible light may be used. The photocurable resin, before being cured, has a viscosity at room temperature (e.g., 25° C.) that is preferably lower than, or equal to, 10 Pa·s, and is especially preferably 1 to 100 mPa·s. In the case where the viscosity is too high, it may be difficult to form a thin film having a thickness of 500 nm or less.

In the above, embodiments of an OLED display device including a flexible substrate and a method for producing the same are described. The embodiments of the present invention are not limited to those described above. An embodiment of the present invention is widely applicable to an organic EL device (e.g., organic EL illumination device) including an organic EL element formed on a substrate that is not flexible (e.g., glass substrate) and a thin film encapsulation structure formed on the organic EL element.

INDUSTRIAL APPLICABILITY

An embodiment of the present invention is applicable to an organic EL device and a method for producing the same. An embodiment of the present invention is especially preferably applicable to an flexible organic EL display device and a method for producing the same.

REFERENCE SIGNS LIST