Display device and method of manufacturing the same

A method of manufacturing a display device includes forming a first resin layer on a first substrate; forming a plurality of regions on the first resin layer, the plurality of regions each including a display portion, a terminal portion and a light blocking layer located between the display portion and the terminal portion; forming a second resin layer on a second substrate; bonding the first substrate and the second substrate; directing first laser light along a first line and a second line enclosing the plurality of regions such that the first laser light is transmitted through the second substrate to irradiate the first resin layer and the second resin layer; and directing second laser light along a third line parallel to the light blocking layer such that the second laser light is transmitted through the second substrate to irradiate the light blocking layer and the second resin layer.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2016-000096 filed on 4thJan. 2016, the entire contents of which are incorporated herein by reference.

FIELD

The present invention relates to a display device including a plurality of pixels and a method of manufacturing the same, and specifically to a display device including a light emitting element including an organic light emitting layer in each of the plurality of pixels, and a method of manufacturing the same.

BACKGROUND

Conventionally, LCDs (Liquid Crystal Displays) and OLED (Organic Light Emitting Diode) displays are manufactured as follows. A plurality of displays are manufactured at the same time on a large glass substrate, and then the glass substrate is cut and separated into the plurality of displays individually. In general, the glass substrate is cut by a method using a scribe cutter or a method using laser light irradiation.

An LCD and an OLED display are each generally have a structure including two glass substrates bonded together. In the above-described cutting step, the two glass substrates are cut together. However, in the state where the two glass substrates are cut in this manner, terminal portions on one of the two glass substrate, namely, an array substrate having a display circuit and the like formed thereon, are covered with the other glass substrate. Therefore, generally, after the two glass substrates are cut together, another step of cutting only the glass substrate not having the terminal portions thereon to expose the terminal portions is performed.

Examples of known technologies for selectively cutting only one of the two substrates bonded together are described in Japanese Laid-Open Patent Publications Nos. 2004-126054 and 2009-98425. According to the technologies disclosed in these publications, each of liquid crystal display devices individually separated is irradiated with laser light to cut a part of one of the two substrates, namely, a counter substrate, to expose the terminal portion on the other substrate, namely, the array substrate. Both of the publications disclose a technology for providing a metal film below a position along which the counter substrate is to be cut, so that the laser light does not hit the array substrate, which is formed of glass.

With the technologies disclosed in the above-mentioned two publications, the step of exposing the terminal portion needs to be performed after the glass substrates are separated into the individual liquid crystal display devices. Namely, the step of laser light irradiation needs to be performed on individual liquid crystal display devices separated from each other from the state of being provided between the large glass substrates. This is a factor decreasing the throughput in the mass-production of the liquid crystal display devices.

SUMMARY

A method of manufacturing a display device in an embodiment according to the present invention includes forming a first resin layer on a first substrate; forming a plurality of regions on the first resin layer, the plurality of regions each including a display portion, a terminal portion and a light blocking layer located between the display portion and the terminal portion; forming a second resin layer on a second substrate; bonding the first substrate and the second substrate such that the first resin layer and the second resin layer face each other; directing first laser light along a first line and a second line enclosing the plurality of regions such that the first laser light is transmitted through the second substrate to irradiate the first resin layer and the second resin layer with the first laser light; and directing second laser light along a third line parallel to the light blocking layer such that the second laser light is transmitted through the second substrate to irradiate the light blocking layer and the second resin layer with the second laser light.

A display device in an embodiment according to the present invention includes a first resin layer including a display portion, a terminal portion electrically connected with the display portion, and a light blocking layer located between the display portion and the terminal portion, the display portion including a light emitting element including a positive electrode, a light emitting layer and a negative electrode, and the light emitting layer forming the same layer as the positive electrode; and a second resin layer bonded to the first resin layer so as to face the first resin layer.

DESCRIPTION OF EMBODIMENTS

The present invention has an object of providing a simple method of manufacturing a display device having a high throughput, and a display device manufactured by such a method.

Hereinafter, embodiments of the present invention will be described with reference to the drawings and the like. The present invention may be carried out in various other embodiments without departing from the gist thereof, and should not be construed as being limited to any of the following embodiments.

In the drawings, components may be shown schematically regarding the width, thickness, shape and the like, instead of being shown in accordance with the actual sizes, for the sake of clear illustration. The drawings are merely exemplary and do not limit the interpretations of the present invention in any way. In the specification and the drawings, components that are substantially the same as those shown in a previous drawing(s) bear the identical reference signs thereto, and overlapping descriptions thereof may be omitted.

In this specification and the claims, an expression that a component or area is “on” another component or area encompasses a case where such a component or area is in contact with the another component or area and also a case where such a component or area is above or below the another component or area, namely, a case where still another component or area is provided between such a component or area and the another component or area, unless otherwise specified.

<Structure of the Display Device>

FIG. 1schematically shows a structure of an organic EL display device10in embodiment 1. The organic EL display device10includes a first resin layer101, a display portion (display region)102provided on the first resin layer101, a terminal portion103provided on the first resin layer101and supplying an external signal to the display portion102, a light blocking layer104located between the display portion102and the terminal portion103, and a second resin layer105located to face the first resin layer101. The display portion102includes a plurality of pixels102alocated therein. The light blocking layer104has a role described below.

Although not shown inFIG. 1, the first resin layer101may have various circuits such as a gate driver circuit, a source driver circuit, a logic circuit and the like provided thereon in addition to the display portion102. The various circuits may be formed of thin film transistors in the same step as the display portion102, or may be provided as external integrated circuits.

FIG. 2shows a cross-sectional structure of the organic EL display device10in embodiment 1. As described above, the display portion102and the terminal portion103are provided on the first resin layer101. The display portion102and the terminal portion103are connected with each other via a plurality of lines106. The lines106have a role of transmitting a signal to the plurality of pixels102aincluded in the display portion102, and are usually formed of a metal material.

As shown inFIG. 1, the display portion102includes the plurality of pixels102a.Each of the pixels102aincludes a plurality of thin film transistors forming a pixel circuit. The structure and the location of each pixel102aare of a known technology. The above-described lines106may be formed in the same step as electrodes or lines electrically connected with the thin film transistors.

As shown inFIG. 2, the display portion102includes an insulating layer107acting as a flattening layer. The insulating layer107may be formed of a resin such as polyimide, acrylic resin or the like or a siloxane-based inorganic insulating material. In the organic EL display device10in this embodiment, the insulating layer107is provided in the display portion102and also in a portion between the display portion102and the terminal portion103. A reason for this will be described below. It is preferable that the insulating layer107is not provided on the terminal portion103because the terminal portion103is exposed in the organic EL display device10as a finished product.

In the display portion102, a positive electrode108, an organic EL layer109including a light emitting layer, and a negative electrode110are provided on the insulating layer107. An organic EL element111as the light emitting element includes the positive electrode108, the organic EL layer109and the negative electrode110. A region enclosed by a bank112formed of an insulating material acts as the pixel102a.The positive electrode108acts as a pixel electrode located in each of the plurality of pixels102a.The negative electrode110is an electrode common to all the plurality of pixels102a, and is provided in the entirety of the display portion102.

Basically, the positive electrode108, the organic EL layer109and the negative electrode110have a structure provided by a known technology. It is preferable that the positive electrode108partially contain a metal material. In the organic EL display device10in this embodiment, the positive electrode108is formed of a stacked film including a transparent conductive layer formed of ITO (indium-tin-oxide) or the like and a metal layer formed of silver or the like. More specifically, the positive electrode108has a structure including two transparent conductive layers and a metal layer sandwiched between the two transparent conductive layers.

In the organic EL display device10in this embodiment, the light blocking layer104is formed in the same step as the positive electrode108. Therefore, the light blocking layer104may have the same layer structure as that of the positive electrode108. In this embodiment, the light blocking layer104may have, for example, a structure including two transparent conductive layers and a metal layer sandwiched between the two transparent conductive layers. Needless to say, the light blocking layer104does not need to have completely the same layer structure as that of the positive electrode108, but may have a part of the structure of the positive electrode108. It should be noted that the light blocking layer104needs to include a metal layer having a light blocking property. In this embodiment, the metal layer formed of silver or the like included in the positive electrode108acts as a metal layer having a light blocking property.

As described above, the insulating layer107needs to be provided below a position where the light blocking layer104is to be provided.FIG. 3shows a structure of the organic EL display device10in this embodiment as seen in a plan view.FIG. 3does not show the second resin layer105.

As described above, the display portion102and the terminal portion103are connected with each other via the plurality of lines106. Therefore, the light blocking layer104cross the plurality of lines106. For this reason, it is preferable that the light blocking layer104and the plurality of lines106are insulated from each other. In order to realize this, the organic EL display device10in this embodiment, as shown inFIG. 2, includes the insulating layer107below the light blocking layer104to insulate the light blocking layer104and the lines106from each other.

As described above, in the organic EL display device10in this embodiment, a part of the metal material used for the positive electrode108included in the organic EL element111is used to form the light blocking layer104. A conductive layer located below the insulating layer107is used to form the lines106. Because of such a structure, the light blocking layer104and the lines106are insulated from each other without any specific step being added. In the case where the insulating layer107is formed of a material having a low dielectric constant (e.g., resin material), a capacitance formed between the light blocking layer104and the lines106is small.

Still referring toFIG. 2, the organic EL element111is covered with a protective layer113. The protective layer113may be formed of, for example, silicon nitride, but is not limited to being formed of silicon nitride. The protective layer113is provided to cover the entirety of the first resin layer101and then is partially etched away as described below. Specifically, a part of the protective layer113that corresponds to a region where the first resin layer101and the second resin layer105do not overlap each other as seen in a plan view (corresponding to a region including the terminal portion103) is selectively removed. As described below, such a step of removal may be performed by etching by use of the second resin layer105as a mask.

The second resin layer105has color filters114and a black mask (light blocking layer)115formed thereon. Neither the color filters114nor the black mask115is indispensable, and the color filters114or the black mask115may be omitted appropriately. For example, in the organic EL display device10in this embodiment, the color filters114are provided because the organic EL layer109is formed of a white organic EL layer. In the case where organic EL layers that emit light of different colors are provided in different pixels, the color filters114may be omitted. Needless to say, even in such a case, the color filters114of colors corresponding to the colors of the light emitted by the respective organic EL layers may be provided in order to improve the color purity. The color filters114and the black mask115may each be formed of a known material.

The first resin layer101and the second resin layer105are bonded together with a sealing member116. In the organic EL display device10in this embodiment, the sealing member116is formed of a resin material. The sealing member116may be formed of any other known material. In this example, the first resin layer101and the second resin layer105are bonded together with the sealing member116. Alternatively, the sealing member116may be omitted. For example, the protective layer113may be formed of a resin material, which may also be used to bond the first resin layer101and the second resin layer105.

<Method of Manufacturing the Display Device10>

Hereinafter, with reference toFIG. 4throughFIG. 15, a method of manufacturing the organic EL display device10in embodiment 1 having the above-described structure will be described.

First, with reference toFIG. 4AandFIG. 4B, a step of manufacturing an array substrate including the display portion102(substrate including a pixel array including the plurality of pixels), among the elements of the organic EL display device10, will be described. As shown inFIG. 4A, a first resin layer32is formed on a first substrate31. The first substrate31may be formed of any appropriate material. In this embodiment, the first substrate31is formed of glass. In this embodiment, the first resin layer32is formed of a polyimide resin, and has a thickness of 10 to 30 μm (typically, 20 μm). The first resin layer32may be formed of any other resin such as an acrylic resin or the like instead of polyimide.

Next, a display portion33and a terminal portion34are formed on the first resin layer32. Specifically, for forming the display portion33, thin film transistors (not shown) are formed by a known method to form a plurality of pixel circuits. In this embodiment, in the step of forming the display portion33, lines35are formed of a metal material such as aluminum or the like. As shown inFIG. 3, ends of the lines35(inFIG. 3, the lines106) are assembled together to form the terminal portion34(inFIG. 3, the terminal portion103). After the thin film transistors are formed, an insulating layer36is formed to cover the thin film transistors. In this embodiment, as described above with reference toFIG. 2andFIG. 3, the insulating layer36(inFIG. 2, the insulating layer107) is formed even in a region below a region where a light blocking layer38(inFIG. 2, the light blocking layer104) is to be formed later.

Next, as shown inFIG. 4B, an organic EL element37is formed on the insulating layer36.FIG. 4Bshows one organic EL element37, but in actuality, an organic EL element37is formed in each of the pixels. As described above with reference toFIG. 2, the organic EL element37(inFIG. 2, the organic EL element111) includes a positive electrode, an organic EL layer and a negative electrode.

In this embodiment, the light blocking layer38is formed in the same step as, and of the same materials as, the positive electrode in the organic EL element37. Specifically, the positive electrode and the light blocking layer38having a structure including two transparent conductive layers formed of ITO and a metal layer formed of silver that is sandwiched between the two transparent conductive layers are formed. Needless to say, the light blocking layer38is not limited to having the above-described structure, but may have any other structure as long as including a metal layer having a light blocking property. A specific role of the light blocking layer38will be described below.

After the organic EL layer37is formed, a protective layer39is formed to cover the entirety of the first substrate31. In this embodiment, the protective layer39is formed of silicon nitride. At this point, the array substrate including the display portion33, among the elements of the organic EL display device10, is manufactured.FIG. 4AandFIG. 4Beach show a region corresponding to one array substrate. In actuality, a plurality of such regions are formed on the first substrate31, which is large-sized. Namely, a plurality of regions each including the display portion33, the terminal portion34, and the light blocking layer38located between the display portion33and the terminal portion34are formed on the first substrate31.

Next, with reference toFIG. 5AandFIG. 5B, a step of manufacturing, among the elements of the organic EL display device10, a counter substrate facing the array substrate will be described.

As shown inFIG. 5A, a second resin layer42is formed on a second substrate41. The second substrate41may be formed of a transparent material such as glass, quartz or the like. In this embodiment, the second substrate41is formed of glass, like the first substrate31. In this embodiment, the second resin layer42is formed of a polyimide resin, and has a thickness of 10 to 30 μm (typically, 20 μm). The second resin layer42may be formed of any other resin such as an acrylic resin or the like instead of polyimide.

Next, as shown inFIG. 5B, a color filter43and a black mask44are formed on the second resin layer42. In this embodiment, the color filter43and the black mask44are formed. Either one of, or both of, the color filter43and the black mask44may be omitted.

InFIG. 5B, the color filter43is shown as being formed in one region. In actuality, a plurality of types of color filters43transmitting light of wavelengths corresponding to the colors of the light emitted in the respective pixels are formed. The black mask44may be formed of a metal material such as chromium or the like, or a resin material containing a black pigment dispersed therein. The color filter43and the black mask44may each have a structure provided by a known technology.

At this point, among the elements of the organic EL display device10, the counter substrate to be located to face the array substrate is manufactured.FIG. 5AandFIG. 5Beach show a region corresponding to one counter substrate. In actuality, a plurality of such regions are formed on the second substrate41, which is large-sized. Namely, a plurality of regions each including the color filter34and the black mask44are formed on the second substrate41.

Next, as shown inFIG. 6, the array substrate (represented by reference sign51) manufactured by the steps shown inFIG. 4AandFIG. 4B, and the counter substrate (represented by reference sign52) manufactured by the steps shown inFIG. 5AandFIG. 5B, are bonded together with a sealing member45. Thus, a plurality of the organic EL display devices10are manufactured in the state of being provided between the first and second substrates31and41.

After the array substrate51and the counter substrate52are bonded together, as shown inFIG. 7andFIG. 8, the assembly of the array substrate51and the counter substrate52is separated into the plurality of individual organic EL display devices10by use of first laser light61.FIG. 7is a cross-sectional view andFIG. 8is a plan view both showing how the assembly of the array substrate51and the counter substrate52is irradiated with the first laser light61.

As shown inFIG. 7, in this embodiment, the assembly of the array substrate51and the counter substrate52is irradiated with the first laser light61directed toward the second substrate41formed of glass. The second resin layer42, the protective layer39, the lines35and the first resin layer32are cut by the first laser light61transmitted through the second substrate41. In this example, the first laser light61is directed toward the second substrate41. Alternatively, the first laser light61may be directed toward the first substrate31as long as the first substrate31is transparent.

The first laser light61may be, for example, excimer laser light, but is not limited to this. The wavelength and the power of the first laser light61may be appropriately selected in consideration of various parameters including the material of each of the first substrate31and the second substrate41, the materials of the elements to be cut, the heat-resistant temperature of each of the first resin layer32and the second resin layer42, and the like.

As shown inFIG. 8, the first laser light61is directed along first lines62and second lines63enclosing regions71each including the display portion33, the terminal portion34and the light blocking layer38(regions enclosed by the chain lines). Namely, the first laser light61is directed along the first lines62and the second lines63crossing each other. As a result, the regions71are separated from each other (it should be noted that in the state shown inFIG. 8, the regions71are still continuous to each other by the first substrate31and the second substrate32).

Next, as shown inFIG. 9andFIG. 10, the second resin layer42is selectively cut by second laser light64.FIG. 9is a cross-sectional view andFIG. 10is a plan view both showing how the assembly of the array substrate51and the counter substrate52is irradiated with the second laser light64.

As shown inFIG. 9, in this embodiment, the assembly of the array substrate51and the counter substrate52is irradiated with the second laser light64directed toward the second substrate41formed of glass. In this embodiment, the second laser light64is blocked by the light blocking layer38in this step. Therefore, the second laser light64does not influence any of the insulating layer36, the lines35and the first resin layer32located below the light blocking layer38. For this reason, the second resin layer42is selectively cut by the second laser light64transmitted through the second substrate41. Thus, it is preferable that the second laser light64has a spot diameter (diameter of an area to be irradiated with the second laser light64) that is less than, or equal to, a line width of the light blocking layer38. For example, in the case where the spot diameter of the second laser light64is10μm, the line width of the light blocking layer38may be 15 to 30 μm (preferably, 20 to 25 μm).

The second laser light64may be, for example, excimer laser light, but is not limited to this. The wavelength and the power of the second laser light64may be appropriately selected in consideration of various parameters including the material of the second substrate41, the material of the second resin layer42, the heat-resistant temperature of the second resin layer42, and the like.

As shown inFIG. 10, the second laser light64is directed along third lines65parallel to the light blocking layers38. In this manner, the second resin layer42is cut along lines crossing regions between the display portions33and the terminal portions34.

In the manner described above, the step of cutting the first resin layer32and the second resin layer42by use of the first laser light61, and the step of cutting the second resin layer42by use of the second laser light64, are finished. In this embodiment, the step of cutting by use of the first laser light61and the step of cutting by use of the second resin layer42may be performed in an opposite order.

Next, as shown inFIG. 11, the assembly of the array substrate51and the counter substrate52is irradiated with third laser light66directed toward the second substrate41in the state where a light blocking mask73is provided on the second substrate41. In this step, a part of an interface between the second substrate41and the second resin layer42is selectively supplied with energy by the third laser light66, which has power lower than that of each of the first laser light61and the second laser light64. As a result, the adhesiveness between the second substrate41and the second resin layer42at the part of the interface is decreased.

Then, as shown inFIG. 12, the second substrate41is removed. In the part irradiated with the third laser light66, the second resin layer42is peeled off from the second substrate41. As a result, the second resin layer42is left above the first substrate31. By contrast, in the part not irradiated with the third laser light66, the second resin layer42is removed together with the second substrate41. In this manner, mere removal of the second substrate41results in a part of the second resin layer42that is in the region above the terminal portion34is selectively removed.

Next, the protective layer39is etched in a self-aligned manner by use of the second resin layer42as a mask, so that as shown inFIG. 13, a part of the line35is exposed. Thus, the terminal portion34is exposed. Namely, exposure of the terminal portion34of the organic EL display device10is finished. It is preferable that the etching performed on the protective layer39is dry etching. A reason for this is that the etching is performed after the organic EL element37is formed and thus it is preferable to avoid, as much as possible, the organic EL element37from being exposed to moisture. In this embodiment, the protective layer39is formed of silicon nitride. Therefore, the dry etching on the protective layer39may be performed by use of, for example, a known gas material such as CF4(carbon fluoride) gas or the like.

In this embodiment, as described above with reference toFIG. 9, the second resin layer42is cut above the light blocking layer38. Therefore, when the dry etching is performed by use of the second resin layer42as a mask, at least a part of the light blocking layer38is exposed. However, in this embodiment, the light blocking layer38is of the same layer structure as the positive electrode included in the organic EL element37. Therefore, the light blocking layer38includes an uppermost layer formed of a transparent conductive material such as ITO or the like. This provides an advantage that even in the case where the light blocking layer38includes a metal layer containing silver, aluminum or the like having a light blocking property, such a metal layer is not exposed, and the problem of corrosion or the like is minimized.

Next, as shown inFIG. 14, the resultant assembly is irradiated with fourth laser light67directed toward the entirety of the first substrate31. In this step, like in the step described above with reference toFIG. 11, an interface between the first substrate31and the first resin layer32is supplied with energy by the fourth laser light67, which has power lower than that of each of the first laser light61and the second laser light64. As a result, the adhesiveness between the first substrate31and the first resin layer32at the interface is decreased. Then, the first substrate31is peeled off from the first resin layer32and thus is removed. As a result, the organic EL display device10shown inFIG. 15is manufactured.

As described above, in this embodiment, an element used for the positive electrode included in the organic EL element37is used for the light blocking layer38, and thus a part of the second resin layer42that is in the region above the terminal portion34is selectively removed without any step being added to the method of manufacturing the organic EL display device10. Before the first substrate31and the second substrate32are removed, the step of cutting the first resin layer32and the second resin layer42is finished. Therefore, mere removal of the second substrate41results in the organic EL display devices10being separated from each other and also results in a part of the second resin layer42that is in the region above the terminal portion34being removed. Namely, the terminal portions34are exposed in the same step in all the organic EL display devices10. Thus, a simple method of manufacturing a display device having a high throughput is provided.

FIG. 16shows a cross-sectional structure of an organic EL display device20in embodiment 2. Unlike in embodiment 1, in the organic EL display device20in embodiment 2, the insulating layer is left below the sealing member without being etched away and the light blocking layer is located also below the sealing member.

As shown inFIG. 16, an insulating layer81is selectively etched so as to be removed from the region where the terminal portion103is to be formed but so as to be left in the display portion102and in a region below a region where the sealing member116is to be formed. Such a structure decreases the amount of the material of the sealing member116and thus decreases the manufacturing cost.

In this embodiment, a light blocking layer82is located also below the sealing member116. Such a structure allows the light blocking layer82to act as an etching stopper and thus to suppress etching gas used for the protective layer113and the laser light from entering the display portion102. Especially, this structure prevents the inconvenience that the insulating layer81located below the sealing member116from being etched away.

The organic EL display device20in this embodiment may be manufactured by a method similar to the manufacturing method in embodiment 1, and the method of manufacturing the organic EL display device20provides effects similar to those of embodiment 1 described above.

The above-described embodiments according to the present invention may be appropriately combined together as long as no contradiction occurs. Any embodiment obtained as a result of any addition, deletion, or design change of an element or any addition, deletion or condition change of a step being performed appropriately by a person of ordinary skill in the art with respect to any of the above-described embodiments is encompassed in the scope of the present invention as long as including the gist of the present invention.

Even a function or effect other than the function or effect provided by the above-described embodiments but is apparent from the description of this specification or would have been obvious to a person of ordinary skill in the art is construed as being provided by the present invention.