DISPLAY DEVICE AND METHOD FOR FABRICATING DISPLAY DEVICE

Abstract

A method for fabricating a highly reliable display device is provided. A first conductive film is formed; a first film containing a first light-emitting substance is formed over the first conductive film; a first mask film is formed over the first film; the first conductive film, the first film, and the first mask film are processed such that their side surfaces are substantially aligned with each other to form a first conductive layer, a first layer, and a first mask layer; a second conductive film is formed over the first mask layer and a first sidewall insulating layer; a second film containing a second light-emitting substance is formed over the second conductive film; a second mask film is formed over the second film; and the second conductive film, the second film, and the second mask film are processed such that their side surfaces are substantially aligned with each other to form a second conductive layer, a second layer, and a second mask layer and to expose the top surface of the first mask layer.

Description

TECHNICAL FIELD

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

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

BACKGROUND ART

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

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

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

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

Reference

Patent Document

Patent Document 1] PCT International Publication No. 2018/087625

SUMMARY OF THE INVENTION

Problems to be Solved by the Invention

An object of one embodiment of the present invention is to provide a display device capable of performing display at high luminance. An object of one embodiment of the present invention is to provide a high-resolution display device. An object of one embodiment of the present invention is to provide a high-definition display device. An object of one embodiment of the present invention is to provide a highly reliable display device.

An object of one embodiment of the present invention is to provide a method for fabricating a high-resolution display device. An object of one embodiment of the present invention is to provide a method for fabricating a high-definition display device. An object of one embodiment of the present invention is to provide a method for fabricating a highly reliable display device. An object of one embodiment of the present invention is to provide a method for fabricating a display device with high yield.

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

Means for Solving the Problems

One embodiment of the present invention is a display device including a first light-emitting device, a second light-emitting device, a first sidewall insulating layer, a second sidewall insulating layer, a third sidewall insulating layer, and an insulating layer. The first light-emitting device includes a first conductive layer, a first layer over the first conductive layer, and a common electrode over the first layer. The second light-emitting device includes a second conductive layer, a second layer over the second conductive layer, and the common electrode over the second layer. An end portion of the first conductive layer overlaps with an end portion of the first layer. The first sidewall insulating layer is in contact with a side surface of the first conductive layer and a side surface of the first layer. An end portion of the second conductive layer overlaps with an end portion of the second layer. The second sidewall insulating layer is in contact with a side surface of the second conductive layer and a side surface of the second layer. The third sidewall insulating layer is in contact with a side surface of the second sidewall insulating layer that is opposite to a side surface of the second sidewall insulating layer in contact with the side surface of the second conductive layer and the side surface of the second layer. The insulating layer overlaps with the side surface and part of a top surface of each of the first conductive layer, the first layer, the second conductive layer, and the second layer. The common electrode is provided over the first layer, the second layer, and the insulating layer.

In the above, the first conductive layer and the second conductive layer each preferably contain a material having a property of reflecting visible light.

In the above, it is preferable that a fourth sidewall insulating layer formed of the second sidewall insulating layer and the third sidewall insulating layer be included, and that a thickness of the fourth sidewall insulating layer be larger than a thickness of the first sidewall insulating layer.

In the above, the first sidewall insulating layer, the second sidewall insulating layer, and the third sidewall insulating layer each preferably contain an inorganic insulating material.

In the above, the insulating layer preferably has a tapered side surface.

In the above, the insulating layer preferably contains an organic insulating material.

Another embodiment of the present invention is a method for fabricating a display device, in which a first conductive film is formed; a first film containing a first light-emitting substance is formed over the first conductive film; a first mask film is formed over the first film; a first conductive layer, a first layer, and a first mask layer are formed by processing the first conductive film, the first film, and the first mask film such that side surfaces of the first conductive film, the first film, and the first mask film are substantially aligned with each other; a second conductive film is formed over the first mask layer; a second film containing a second light-emitting substance is formed over the second conductive film; a second mask film is formed over the second film; and a second conductive layer, a second layer, and a second mask layer are formed and a top surface of the first mask layer is exposed by processing the second conductive film, the second film, and the second mask film such that side surfaces of the second conductive film, the second film, and the second mask film are substantially aligned with each other.

In the above, each of the first conductive film and the second conductive film is preferably formed using a material having a property of reflecting visible light.

In the above, it is preferable that the first film be formed using a material containing the first light-emitting substance emitting blue light, and that the second film be formed using a second material emitting visible light having a longer wavelength than blue light.

In the above, it is preferable that a first insulating film be formed over the first mask layer and the second mask layer after the second conductive layer, the second layer, and the second mask layer are formed; a second insulating film be formed over the first insulating film; an insulating layer be formed in a region between the first conductive layer and the second conductive layer by processing the second insulating film; the first insulating film, the first mask layer, and the second mask layer be processed to expose a top surface of the first layer and a top surface of the second layer by etching treatment using the insulating layer as a mask; and a common electrode be formed to cover the first layer, the second layer, and the insulating layer.

In the above, it is preferable that an aluminum oxide film be formed by an ALD method as the first insulating film, and that an aluminum oxide film be formed by an ALD method as each of the first mask film and the second mask film.

In the above, the second insulating film is preferably formed using a photosensitive acrylic resin.

In the above, the etching treatment is preferably divided into first etching treatment and second etching treatment. In the first etching treatment using the insulating layer as a mask, the first insulating film, the first mask layer, and the second mask layer are preferably processed to remove part of the first insulating film and reduce thicknesses of part of the first mask layer and part of the second mask layer. In the second etching treatment using the insulating layer as a mask after heat treatment, the part of the first mask layer and the part of the second mask layer are preferably removed to expose the top surface of the first layer and the top surface of the second layer.

In the above, the first etching treatment and the second etching treatment are preferably performed by wet etching.

In the above, it is preferable that a first sidewall insulating film be formed in contact with a side surface of the first conductive layer, a side surface of the first layer, and a side surface and the top surface of the first mask layer after the first conductive layer, the first layer, and the first mask layer are formed; a first sidewall insulating layer in contact with the side surface of the first conductive layer and the side surface of the first layer be formed by processing the first sidewall insulating film by anisotropic etching; a second sidewall insulating film be formed in contact with a side surface of the second conductive layer, a side surface of the second layer, and a side surface and a top surface of the second mask layer after the second conductive film, the second film, and the second mask layer are formed; and a second sidewall insulating layer in contact with the side surface of the second conductive layer and the side surface of the second layer and a third sidewall insulating layer in contact with a side surface of the first sidewall insulating layer that is opposite to a side surface of the first sidewall insulating layer in contact with the first conductive layer, the first layer, and the first mask layer be formed by processing the second sidewall insulating film by anisotropic etching.

In the above, an aluminum oxide film is preferably formed by an ALD method as each of the first sidewall insulating film and the second sidewall insulating film.

Effect of the Invention

One embodiment of the present invention can provide a display device capable of performing display at high luminance. One embodiment of the present invention can provide a high-resolution display device. One embodiment of the present invention can provide a high-definition display device. One embodiment of the present invention can provide a highly reliable display device.

One embodiment of the present invention can provide a method for fabricating a high-resolution display device. One embodiment of the present invention can provide a method for fabricating a high-definition display device. One embodiment of the present invention can provide a method for fabricating a highly reliable display device. One embodiment of the present invention can provide a method for fabricating a display device with high yield.

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

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a top view illustrating an example of a display device. FIG. 1B is a cross-sectional view illustrating an example of the display device.

FIG. 2A and FIG. 2B are cross-sectional views illustrating an example of a display device.

FIG. 3A and FIG. 3B are cross-sectional views illustrating an example of a display device.

FIG. 4A and FIG. 4B are cross-sectional views illustrating examples of a display device.

FIG. 5A and FIG. 5B are cross-sectional views illustrating examples of a display device.

FIG. 6A and FIG. 6B are cross-sectional views illustrating examples of a display device.

FIG. 7A is a cross-sectional view illustrating an example of a display device. FIG. 7B and FIG. 7C are cross-sectional views illustrating examples of a pixel electrode.

FIG. 8A to FIG. 8C are cross-sectional views illustrating examples of a display device.

FIG. 9A to FIG. 9C are cross-sectional views illustrating examples of a display device.

FIG. 10A and FIG. 10B are cross-sectional views illustrating examples of a display device.

FIG. 11A to FIG. 11C are cross-sectional views illustrating examples of a display device.

FIG. 12A and FIG. 12B are cross-sectional views illustrating examples of a display device.

FIG. 13A is a top view illustrating an example of a display device. FIG. 13B is a cross-sectional view illustrating an example of the display device.

FIG. 14A to FIG. 14C are cross-sectional views illustrating an example of a method for fabricating a display device.

FIG. 15A to FIG. 15C are cross-sectional views illustrating an example of a method for fabricating a display device.

FIG. 16A to FIG. 16C are cross-sectional views illustrating an example of a method for fabricating a display device.

FIG. 17A to FIG. 17C are cross-sectional views illustrating an example of a method for fabricating a display device.

FIG. 18A to FIG. 18C are cross-sectional views illustrating an example of a method for fabricating a display device.

FIG. 19A to FIG. 19C are cross-sectional views illustrating an example of a method for fabricating a display device.

FIG. 20A to FIG. 20C are cross-sectional views illustrating an example of a method for fabricating a display device.

FIG. 21A to FIG. 21C are cross-sectional views illustrating an example of a method for fabricating a display device.

FIG. 22A to FIG. 22C are cross-sectional views illustrating an example of a method for fabricating a display device.

FIG. 23A to FIG. 23C are cross-sectional views illustrating an example of a method for fabricating a display device.

FIG. 24A and FIG. 24B are cross-sectional views illustrating an example of a method for fabricating a display device.

FIG. 25A to FIG. 25F are cross-sectional views illustrating an example of a method for fabricating a display device.

FIG. 26A to FIG. 26C are cross-sectional views illustrating an example of a method for fabricating a display device.

FIG. 27A and FIG. 27B are cross-sectional views illustrating an example of a method for fabricating a display device.

FIG. 28A to FIG. 28G are diagrams illustrating examples of pixels.

FIG. 29A to FIG. 29K are diagrams illustrating examples of a pixel.

FIG. 30A and FIG. 30B are perspective views illustrating an example of a display device.

FIG. 31A to FIG. 31C are cross-sectional views illustrating examples of a display device.

FIG. 32 is a cross-sectional view illustrating an example of a display device.

FIG. 33 is a cross-sectional view illustrating an example of a display device.

FIG. 34 is a cross-sectional view illustrating an example of a display device.

FIG. 35 is a cross-sectional view illustrating an example of a display device.

FIG. 36 is a cross-sectional view illustrating an example of a display device.

FIG. 37 is a perspective view illustrating an example of a display device.

FIG. 38A is a cross-sectional view illustrating an example of a display device. FIG. 38B and FIG. 38C are cross-sectional views illustrating examples of transistors.

FIG. 39A to FIG. 39D are cross-sectional views illustrating examples of a display device.

FIG. 40 is a cross-sectional view illustrating an example of a display device.

FIG. 41A to FIG. 41F are diagrams illustrating structure examples of light-emitting devices.

FIG. 42A to FIG. 42C are diagrams illustrating structure examples of light-emitting devices.

FIG. 43A and FIG. 43B are diagrams illustrating structure examples of light-receiving devices.

FIG. 43C to FIG. 43E are diagrams illustrating a structure example of a display device.

FIG. 44A to FIG. 44D are diagrams illustrating examples of electronic devices.

FIG. 45A to FIG. 45F are diagrams illustrating examples of electronic devices.

FIG. 46A to FIG. 46G are diagrams illustrating examples of electronic devices.

MODE FOR CARRYING OUT THE INVENTION

Embodiments will be described in detail with reference to the drawings. Note that the present invention is not limited to the following description, and it will be readily appreciated by those skilled in the art that modes and details of the present invention can be modified in various ways without departing from the spirit and scope of the present invention. Therefore, the present invention should not be construed as being limited to the description in the following embodiments.

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

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

Note that the term “film” and the term “layer” can be used interchangeably depending on the case or the circumstances. For example, the term “conductive layer” can be replaced with the term “conductive film”. For another example, the term “insulating film” can be replaced with the term “insulating layer”.

In this specification and the like, a device formed using a metal mask or an FMM (fine metal mask, high-resolution metal mask) may be referred to as a device having an MM (metal mask) structure. In this specification and the like, a device formed without using a metal mask or an FMM may be referred to as a device having an MML (metal maskless) structure.

In this specification and the like, a structure in which at least light-emitting layers of light-emitting devices having different emission wavelengths are separately formed may be referred to as an SBS (Side By Side) structure. The SBS structure can optimize materials and structures of light-emitting devices and thus can extend freedom of choice of materials and structures, whereby the luminance and the reliability can be easily improved.

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

In this specification and the like, a light-emitting device (also referred to as a light-emitting element) includes an EL layer between a pair of electrodes. The EL layer includes at least a light-emitting layer. Examples of layers (also referred to as functional layers) included in the EL layer include a light-emitting layer, carrier-injection layers (a hole-injection layer and an electron-injection layer), carrier-transport layers (a hole-transport layer and an electron-transport layer), and carrier-blocking layers (a hole-blocking layer and an electron-blocking layer).

In this specification and the like, a light-receiving device (also referred to as a light-receiving element) includes at least an active layer functioning as a photoelectric conversion layer between a pair of electrodes.

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

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

In this specification and the like, a mask layer (also referred to as a sacrificial layer, a protective layer, or the like) is positioned above at least a light-emitting layer (specifically, a layer processed into an island shape among layers included in an EL layer) and has a function of protecting the light-emitting layer in the manufacturing process.

Embodiment 1

In this embodiment, a display device of one embodiment of the present invention will be described with reference to FIG. 1A to FIG. 13B.

A display device of one embodiment of the present invention includes light-emitting devices separately formed for respective emission colors and can perform full-color display.

In the case of fabricating a display device including a plurality of light-emitting devices emitting light of different colors, light-emitting layers emitting light of different colors each need to be formed into an island shape.

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

In view of this, in fabricating the display device of one embodiment of the present invention, fine patterning of light-emitting layers is performed by a photolithography method without using a shadow mask such as a metal mask. Specifically, a conductive film to be a pixel electrode and a film to be a light-emitting layer are formed for each subpixel. After that, the conductive film and the layer are processed by a photolithography method, so that an island-shaped pixel electrode and an island-shaped light-emitting layer are formed. Thus, the light-emitting layer is divided for each subpixel, so that island-shaped light-emitting layers can be formed for the respective subpixels.

For example, in the case where the display device includes three kinds of light-emitting devices, which are a light-emitting device emitting blue light (also simply referred to as a blue-light-emitting device), a light-emitting device emitting green light (also simply referred to as a green-light-emitting device), and a light-emitting device emitting red light (also simply referred to as a red-light-emitting device), three kinds of island-shaped light-emitting layers can be formed by repetition of formation of a light-emitting layer and processing by photolithography three times.

Here, for the characteristics of the light-emitting device, the state of the interface between the pixel electrode and the EL layer is important. In the formation process of the island-shaped light-emitting layers, the pixel electrode of the light-emitting device of the color formed second or later is sometimes damaged by the preceding step. This might degrade the state of the interface between the pixel electrode and the EL layer of the light-emitting device of the color formed second or later, so that the driving voltage of the light-emitting device might be high.

In view of this, in one embodiment of the present invention, a conductive film to be a pixel electrode and a film including a light-emitting layer are successively formed and then successively processed to form an island-shaped pixel electrode and an island-shaped light-emitting layer for each light-emitting device, instead of forming island-shaped light-emitting layers after the pixel electrodes of all the light-emitting devices are formed. This prevents the pixel electrode from being exposed in the formation of the light-emitting layer in each light-emitting device. Thus, when the light-emitting layer in one light-emitting device is formed, the pixel electrodes of the other light-emitting devices where the light-emitting layers are not formed can be prevented from being damaged by the formation process. Accordingly, a good state of the interface between the pixel electrode and the EL layer of each light-emitting device is maintained, which can inhibit generation of a defect such as an increase in the driving voltage of the light-emitting device of the color formed second or later. Inhibiting the increase in the driving voltage of each light-emitting device can increase the lifetime and reliability of each light-emitting device.

Note that in the case where the conductive film to be the pixel electrode and the film including the light-emitting layer are collectively processed in each light-emitting device as described above, the end portions of the island-shaped pixel electrode and the island-shaped light-emitting layer substantially overlap with each other (the side surfaces thereof are substantially aligned with each other). Thus, the side surface of the pixel electrode is exposed after the processing; when a film above the pixel electrode is then processed by a wet etching method, for example, a defect such as corrosion of the pixel electrode due to an etchant that is in direct contact with the pixel electrode might be induced.

In view of this, in one embodiment of the present invention, a sidewall insulating layer (also referred to as a sidewall, a sidewall protective layer, an insulating layer, or the like) covering the side surfaces of the pixel electrode and the light-emitting layer is preferably provided after the formation of the island-shaped pixel electrode and the island-shaped light-emitting layer. This protects the side surface of the pixel electrode, thereby inhibiting generation of the above-described defect. In addition, the pixel electrode is inhibited from being in contact with a common electrode provided over the EL layer, which can prevent a short circuit in the light-emitting device.

Providing the sidewall insulating layer also protects the end portion of the light-emitting layer. This can inhibit generation of a defect in a later step, such as damage to the end portion of the light-emitting layer or degradation of the characteristics of the light-emitting device due to entry of impurities or the like through the end portion of the light-emitting layer.

In the case of processing the light-emitting layer into an island shape, a structure is possible in which processing is performed by a photolithography method directly on the light-emitting layer. In the case of the above structure, damage to the light-emitting layer (e.g., processing damage) might significantly degrade the reliability. In view of this, in fabrication of the display device of one embodiment of the present invention, a method is preferably employed in which a mask layer or the like is formed over a functional layer (e.g., a carrier-blocking layer, a carrier-transport layer, or a carrier-injection layer, specifically a hole-blocking layer, an electron-transport layer, an electron-injection layer, or the like) above the light-emitting layer, followed by the processing of the light-emitting layer and the functional layer into an island shape. By employing such a method, a highly reliable display device can be provided. A functional layer between the light-emitting layer and the mask layer can inhibit the light-emitting layer from being exposed on the outermost surface during the fabrication process of the display device and can reduce damage to the light-emitting layer.

In the case where the light-emitting layer is processed into an island shape, a layer positioned below the light-emitting layer (e.g., a carrier-injection layer, a carrier-transport layer, or a carrier-blocking layer, specifically a hole-injection layer, a hole-transport layer, an electron-blocking layer, or the like) is preferably processed into an island shape with the same pattern as the light-emitting layer. Processing a layer positioned below the light-emitting layer into an island shape with the same pattern as the light-emitting layer can reduce leakage current (sometimes referred to as horizontal-direction leakage current, horizontal leakage current, or lateral leakage current) that might be generated between adjacent subpixels. For example, in the case where the hole-injection layer is shared by adjacent subpixels, horizontal leakage current due to the hole-injection layer might be generated. Meanwhile, in the display device of one embodiment of the present invention, the hole-injection layer can be processed into an island shape with the same pattern as the light-emitting layer; thus, horizontal leakage current between adjacent subpixels is not substantially generated or horizontal leakage current can be extremely small.

In the case of performing processing by a photolithography method, for example, the EL layer might suffer from various kinds of damage due to heating at the time of resist mask formation and exposure to an etchant or an etching gas at the time of resist mask processing or removal. In the case where a mask layer is provided over the EL layer, the EL layer might be affected by heating, an etchant, an etching gas, or the like in forming, processing, and removing the mask layer.

In addition, when steps performed after formation of the EL layer are performed at temperature higher than the upper temperature limit of the EL layer, degradation of the EL layer proceeds, which might result in a decrease in the emission efficiency and reliability of the light-emitting device.

Thus, in one embodiment of the present invention, the upper temperature limit of a compound contained in the light-emitting device is preferably higher than or equal to 100° C. and lower than or equal to 180° C., further preferably higher than or equal to 120° C. and lower than or equal to 180° C., still further preferably higher than or equal to 140° C. and lower than or equal to 180° C.

Examples of indicators of the upper temperature limit include the glass transition point (Tg), the softening point, the melting point, the thermal decomposition temperature, and the 5% weight loss temperature. For example, as an indicator of the upper temperature limit of a layer included in the EL layer, a glass transition point of a material contained in the layer can be used. In the case where the layer is a mixed layer formed of a plurality of materials, a glass transition point of a material contained in the highest proportion can be used, for example. Alternatively, the lowest temperature among the glass transition points of the materials may be used.

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

In addition, it is particularly preferable that the upper temperature limit of the light-emitting layer be high. In that case, the light-emitting layer can be inhibited from being damaged by heating and being decreased in emission efficiency and lifetime.

Increasing the upper temperature limit of the light-emitting device can improve the reliability of the light-emitting device. Furthermore, the allowable temperature range in the fabrication process of the display device can be widened, thereby improving the manufacturing yield and the reliability.

It is not necessary to form all layers included in the EL layers separately between light-emitting devices emitting light of different colors, and some layers can be formed in the same step. In the method for fabricating the display device of one embodiment of the present invention, some layers included in the EL layers are formed into an island shape separately for each color, and then at least part of the mask layer is removed. After that, the other layers (sometimes referred to as common layers) included in the EL layers and a common electrode (also referred to as an upper electrode) are formed to be shared by the light-emitting devices of different colors (formed as one film). For example, the carrier-injection layer and the common electrode can be formed to be shared by the light-emitting devices of different colors.

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

In view of the above, the display device of one embodiment of the present invention includes, in addition to the above-described sidewall insulating layer, an insulating layer covering at least the side surface of the island-shaped light-emitting layer. The insulating layer preferably covers part of the top surface of the island-shaped light-emitting layer.

Thus, at least some layers in the EL layer formed into an island shape and the pixel electrode can be inhibited from being in contact with the carrier-injection layer or the common electrode. Hence, a short circuit in the light-emitting device is inhibited, and the reliability of the light-emitting device can be improved.

In a cross-sectional view, the end portion of the insulating layer preferably has a tapered shape with a taper angle less than 90°. In that case, step disconnection of the common layer and the common electrode provided over the insulating layer can be prevented. Thus, connection defects caused by step disconnection of the common layer and the common electrode can be inhibited. It is also possible to inhibit an increase in the electric resistance of the common layer and the common electrode, which is caused by local thinning of the common layer and the common electrode due to a step of the end portion of the insulating layer.

Note that in this specification and the like, step disconnection refers to a phenomenon in which a layer, a film, or an electrode is split because of the shape of the formation surface (e.g., a step).

Thus, in the method for fabricating a display device of one embodiment of the present invention, an island-shaped light-emitting layer is formed not by using a fine metal mask but by processing a light-emitting layer formed on the entire surface. Accordingly, a high-resolution display device or a display device with a high aperture ratio, which has been difficult to achieve so far, can be provided. Moreover, light-emitting layers can be formed separately for each color, enabling the display device to perform extremely clear display with high contrast and high display quality. Moreover, providing the mask layer over the light-emitting layer can reduce damage to the light-emitting layer in the fabrication process of the display device, resulting in an improvement in reliability of the light-emitting device.

It is difficult to reduce the distance between adjacent light-emitting devices to less than 10 μm with a formation method using a fine metal mask, for example; however, the method employing a photolithography method of one embodiment of the present invention can shorten the distance between adjacent light-emitting devices, the distance between adjacent EL layers, the distance between adjacent sidewall insulating layers, or the distance between adjacent pixel electrodes to less than 10 μm, less than or equal to 5 μm, less than or equal to 3 μm, less than or equal to 2 μm, less than or equal to 1.5 μm, less than or equal to 1 μm, or even less than or equal to 0.5 μm, for example, in a process over a glass substrate. Using a light exposure apparatus for LSI can further shorten the distance between adjacent light-emitting devices, the distance between adjacent EL layers, the distance between adjacent sidewall insulating layers, or the distance between adjacent pixel electrodes to less than or equal to 500 nm, less than or equal to 200 nm, less than or equal to 100 nm, or even less than or equal to 50 nm, for example, in a process over a Si wafer. Accordingly, the area of a non-light-emitting region that may exist between two light-emitting devices can be significantly reduced, and the aperture ratio can be close to 100%. For example, the display device of one embodiment of the present invention can have an aperture ratio higher than or equal to 40%, higher than or equal to 50%, higher than or equal to 60%, higher than or equal to 70%, higher than or equal to 80%, or higher than or equal to 90%, and lower than 100%.

Furthermore, a processing size of the light-emitting layer itself can be made much smaller than that in the case of using a fine metal mask. For example, in the case of using a metal mask for forming light-emitting layers separately, a variation in the thickness occurs between the center and the edge of the light-emitting layer after processing, which causes a reduction in an effective area that can be used as a light-emitting region with respect to the whole area of the light-emitting layer after processing. By contrast, in the above fabrication method, the film formed to have a uniform thickness is processed, so that island-shaped light-emitting layers can be formed to have a uniform thickness. Accordingly, even when the processing size of the light-emitting layer is minute, almost the whole area can be used as a light-emitting region. Thus, a display device having both a high resolution and a high aperture ratio can be fabricated. Furthermore, the display device can be reduced in size and weight.

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

In this embodiment, cross-sectional structures of the display device of one embodiment of the present invention are mainly described, and a method for fabricating the display device of one embodiment of the present invention will be described in detail in Embodiment 2.

FIG. 1A illustrates a top view of a display device 100. The display device 100 includes a display portion where a plurality of pixels 110 are arranged, and a connection portion 140 outside the display portion. A plurality of subpixels are arranged in a matrix in the display portion. FIG. 1A illustrates subpixels in two rows and six columns, which form the pixels 110 in two rows and two columns. The connection portion 140 can also be referred to as a cathode contact portion.

The top surface shape of each subpixel illustrated in FIG. 1A corresponds to the top surface shape of a light-emitting region.

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

The range of the circuit layout for forming the subpixels is not limited to the range of the subpixels illustrated in FIG. 1A, and the components may be placed outside the range of the subpixels. For example, transistors (not illustrated) included in a subpixel 11R may be positioned within the range of a subpixel 11G illustrated in FIG. 1A, or some or all of the transistors may be positioned outside the range of the subpixel 11R.

Although FIG. 1A illustrates the subpixel 11R, the subpixel 11G, and a subpixel 11B that have the same or substantially the same aperture ratio (also referred to as size or size of a light-emitting region), one embodiment of the present invention is not limited thereto. The aperture ratio of each of the subpixel 11R, the subpixel 11G, and the subpixel 11B can be determined as appropriate. The subpixel 11R, the subpixel 11G, and the subpixel 11B may have different aperture ratios, or two or more of them may have the same or substantially the same aperture ratio.

The pixels 110 illustrated in FIG. 1A employ stripe arrangement. The pixels 110 illustrated in FIG. 1A are each composed of three subpixels: the subpixel 11R, the subpixel 11G, and the subpixel 11B. The subpixel 11R, the subpixel 11G, and the subpixel 11B include light-emitting devices emitting light of different colors. The subpixel 11R, the subpixel 11G, and the subpixel 11B are subpixels of three colors of red (R), green (G), and blue (B) or subpixels of three colors of yellow (Y), cyan (C), and magenta (M), for example. The number of types of subpixels is not limited to three and may be four or more. The four subpixels are subpixels of four colors of R, G, B, and white (W), subpixels of four colors of R, G, B, and Y, or four subpixels of R, G, B, and infrared light (IR), for example.

In this specification and the like, the directions perpendicular to sides of a pixel or a subpixel are referred to as X direction and Y direction in some cases. The X direction and the Y direction intersect with each other and are, for example, orthogonal to each other (see FIG. 1A). FIG. 1A illustrates an example in which subpixels of different colors are arranged in the X direction and subpixels of the same color are arranged in the Y direction. Note that the display device of one embodiment of the present invention is not limited thereto; subpixels of the same color may be arranged in the X direction, and subpixels of different colors may be arranged in the Y direction.

The plan view in FIG. 1A illustrates, but one embodiment of the present invention is not particularly limited to, an example in which the connection portion 140 is positioned in the lower side of the display portion. The connection portion 140 is provided in at least one of the upper side, the right side, the left side, and the lower side of the display portion in the plan view, and may be provided to surround the four sides of the display portion. The top surface shape of the connection portion 140 can be a belt-like shape, an L shape, a U shape, a frame-like shape, or the like. The number of connection portions 140 may be one or more.

FIG. 1B illustrates a cross-sectional view along the dashed-dotted line X1-X2 in FIG. 1A. FIG. 2A and FIG. 2B illustrate enlarged views of part of the cross-sectional view illustrated in FIG. 1B. FIG. 3 to FIG. 6 illustrate variation examples of FIG. 2. FIG. 7A and FIG. 8 to FIG. 11 illustrate variation examples of FIG. 1B. FIG. 7B and FIG. 7C are cross-sectional views illustrating variation examples of a pixel electrode. FIG. 12A and FIG. 12B illustrate cross-sectional views along the dashed-dotted line Y1-Y2 in FIG. 1A.

As illustrated in FIG. 1B, in the display device 100, insulating layers (an insulating layer 255a, an insulating layer 255b, and an insulating layer 255c) are provided over a layer 101 including transistors (not illustrated), a light-emitting device 130R, a light-emitting device 130G, and a light-emitting device 130B are provided over the insulating layers, and a protective layer 131 is provided to cover these light-emitting devices. A substrate 120 is bonded onto the protective layer 131 with a resin layer 122. In a region between adjacent light-emitting devices (a non-light-emitting region), an insulating layer 125 and an insulating layer 127 over the insulating layer 125 are provided.

Although FIG. 1B illustrates a plurality of cross sections of the insulating layer 125 and the insulating layer 127, the insulating layer 125 and the insulating layer 127 are each one continuous layer when the display device 100 is seen from above. In other words, the display device 100 can have a structure including one insulating layer 125 and one insulating layer 127, for example. Note that the display device 100 may include a plurality of the insulating layers 125 that are separated from each other, and may include a plurality of the insulating layers 127 that are separated from each other.

The display device of one embodiment of the present invention can have any of a top-emission structure in which light is emitted in a direction opposite to the substrate where the light-emitting device is formed, a bottom-emission structure in which light is emitted toward the substrate where the light-emitting device is formed, and a dual-emission structure in which light is emitted toward both surfaces.

The layer 101 can employ a stacked-layer structure in which a plurality of transistors (not illustrated) are provided over a substrate and insulating layers are provided to cover these transistors, for example. The insulating layers over the transistors may each have a single-layer structure or a stacked-layer structure. In FIG. 1B, the insulating layer 255a, the insulating layer 255b over the insulating layer 255a, and the insulating layer 255c over the insulating layer 255b are illustrated as the insulating layers over the transistors. These insulating layers may have a depressed portion in a region between adjacent light-emitting devices (a non-light-emitting region). The insulating layer 255c does not necessarily include a depressed portion between adjacent light-emitting devices. In the example illustrated in FIG. 1B and the like, the insulating layer 255c is not provided with a depressed portion. The insulating layers (the insulating layer 255a to the insulating layer 255c) over the transistors can be regarded as part of the layer 101.

As each of the insulating layer 255a, the insulating layer 255b, and the insulating layer 255c, any of a variety of inorganic insulating films such as an oxide insulating film, a nitride insulating film, an oxynitride insulating film, and a nitride oxide insulating film can be suitably used. As each of the insulating layer 255a and the insulating layer 255c, an oxide insulating film or an oxynitride insulating film, such as a silicon oxide film, a silicon oxynitride film, or an aluminum oxide film, is preferably used. As the insulating layer 255b, a nitride insulating film or a nitride oxide insulating film, such as a silicon nitride film or a silicon nitride oxide film, is preferably used. Specifically, it is preferable that a silicon oxide film be used as each of the insulating layer 255a and the insulating layer 255c and a silicon nitride film be used as the insulating layer 255b. The insulating layer 255b preferably has a function of an etching protective film.

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

Structure examples of the layer 101 will be described later in Embodiment 4.

The light-emitting device 130R emits red (R) light, the light-emitting device 130G emits green (G) light, and the light-emitting device 130B emits blue (B) light.

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

The emission color of the light-emitting device can be infrared, red, green, blue, cyan, magenta, yellow, white, or the like. When the light-emitting device has a microcavity structure, the color purity can be increased.

Embodiment 5 can be referred to for the structure and the materials of the light-emitting device.

One of a pair of electrodes included in the light-emitting device functions as an anode, and the other electrode functions as a cathode. The case where the pixel electrode functions as an anode and the common electrode functions as a cathode is described below as an example in some cases.

The light-emitting device 130R includes an island-shaped conductive layer 111R over the insulating layer 255c, an island-shaped layer 113R over the island-shaped conductive layer 111R, a common layer 114 over the island-shaped layer 113R, and a common electrode 115 over the common layer 114. In the light-emitting device 130R, the conductive layer 111R can be referred to as a pixel electrode. In the light-emitting device 130R, the layer 113R and the common layer 114 can be collectively referred to as an EL layer.

The light-emitting device 130G includes an island-shaped conductive layer 111G over the insulating layer 255c, an island-shaped layer 113G over the island-shaped conductive layer 111G, the common layer 114 over the island-shaped layer 113G, and the common electrode 115 over the common layer 114. In the light-emitting device 130G, the conductive layer 111G can be referred to as a pixel electrode. In the light-emitting device 130G, the layer 113G and the common layer 114 can be collectively referred to as an EL layer.

The light-emitting device 130B includes an island-shaped conductive layer 111B over the insulating layer 255c, an island-shaped layer 113B over the island-shaped conductive layer 111B, the common layer 114 over the island-shaped layer 113B, and the common electrode 115 over the common layer 114. In the light-emitting device 130B, the conductive layer 111B can be referred to as a pixel electrode. In the light-emitting device 130B, the layer 113B and the common layer 114 can be collectively referred to as an EL layer.

In this specification and the like, in the EL layers included in the light-emitting devices, the island-shaped layer provided in each light-emitting device is referred to as the layer 113R, the layer 113G, or the layer 113B, and the layer shared by the plurality of light-emitting devices is referred to as the common layer 114. Note that in this specification and the like, the layer 113R, the layer 113G, and the layer 113B are sometimes referred to as island-shaped EL layers, EL layers formed into an island shape, or the like, in which case the common layer 114 is not included.

The layer 113R, the layer 113G, and the layer 113B are isolated from each other. When the EL layer is provided in an island shape for each light-emitting device, leakage current between adjacent light-emitting devices (light-emitting regions) can be inhibited. This can prevent crosstalk due to unintended light emission, so that a display device with extremely high contrast can be obtained. Specifically, a display device having high current efficiency at low luminance can be obtained.

The end portion of the island-shaped conductive layer 111R and the end portion of the island-shaped layer 113R provided over the conductive layer 111R are substantially aligned with each other. The end portion of the island-shaped conductive layer 111G and the end portion of the island-shaped layer 113G provided over the conductive layer 111G are substantially aligned with each other. Similarly, the end portion of the island-shaped conductive layer 111B and the end portion of the island-shaped layer 113B provided over the conductive layer 111B are substantially aligned with each other.

As described above, in one embodiment of the present invention, the conductive film to be the pixel electrode and the film including the light-emitting layer are successively formed and then successively processed to form the island-shaped pixel electrode and the island-shaped light-emitting layer for each light-emitting device, instead of forming the island-shaped light-emitting layers (the layer 113R, the layer 113G, and the layer 113B) after the pixel electrodes (the conductive layer 111R, the conductive layer 111G, and the conductive layer 111B) of all the light-emitting devices are formed. Thus, the end portion of the island-shaped conductive layer 111R and the end portion of the island-shaped layer 113R can be formed to be substantially aligned with each other, the end portion of the island-shaped conductive layer 111G and the end portion of the island-shaped layer 113G can be formed to be substantially aligned with each other, and the end portion of the island-shaped conductive layer 111B and the end portion of the island-shaped layer 113B can be formed to be substantially aligned with each other. The details of a method for fabricating the display device of one embodiment of the present invention will be described in Embodiment 2.

A sidewall insulating layer 107R_1 is provided in contact with the side surfaces of the conductive layer 111R and the layer 113R.

A sidewall insulating layer 107G_1 is provided in contact with the side surfaces of the conductive layer 111G and the layer 113G. A sidewall insulating layer 107G_2 is provided in contact with the side surface of the sidewall insulating layer 107G_1 that is opposite to the side surface thereof in contact with the conductive layer 111G and the layer 113G.

A sidewall insulating layer 107B_1 is provided in contact with the side surfaces of the conductive layer 111B and the layer 113B. A sidewall insulating layer 107B_2 is provided in contact with the side surface of the sidewall insulating layer 107B_1 that is opposite to the side surface thereof in contact with the conductive layer 111B and the layer 113B. A sidewall insulating layer 107B_3 is provided in contact with the side surface of the sidewall insulating layer 107B_2 that is opposite to the side surface thereof in contact with the sidewall insulating layer 107B_1.

Here, the sidewall insulating layer 107R_1, the sidewall insulating layer 107G_1, the sidewall insulating layer 107G_2, the sidewall insulating layer 107B_1, the sidewall insulating layer 107B_2, and the sidewall insulating layer 107B_3 can be formed using the same material as described later in Embodiment 2. Thus, the boundaries between the sidewall insulating layers (e.g., the boundary between the sidewall insulating layer 107G_1 and the sidewall insulating layer 107G_2 and the boundaries between the sidewall insulating layer 107B_1, the sidewall insulating layer 107B_2, and the sidewall insulating layer 107B_3) are unclear so that the sidewall insulating layers are recognized as one sidewall insulating layer in some cases. Accordingly, the thickness of one sidewall insulating layer that is in contact with the side surfaces of the conductive layer 111G and the layer 113G included in the light-emitting device 130G (the total thickness of the sidewall insulating layer 107G_1 and the sidewall insulating layer 107G_2) can be regarded as being larger than the thickness of one sidewall insulating layer that is in contact with the side surfaces of the conductive layer 111R and the layer 113R included in the light-emitting device 130R (the thickness of the sidewall insulating layer 107R_1), and the thickness of one sidewall insulating layer that is in contact with the side surfaces of the conductive layer 111B and the layer 113B included in the light-emitting device 130B (the total thickness of the sidewall insulating layer 107B_1, the sidewall insulating layer 107B_2, and the sidewall insulating layer 107B_3) can be regarded as being larger than the total thickness of the sidewall insulating layer 107G_1 and the sidewall insulating layer 107G_2.

In the display device of one embodiment of the present invention, including the above-described sidewall insulating layers can prevent generation of a defect such as a change in the quality of the conductive layer 111, for example, caused by corrosion (e.g., galvanic corrosion) of the conductive layer 111 due to impurities or the like contained in an etchant that is used for processing a film above the pixel electrode by a wet etching method and is in direct contact with the conductive layer 111 (the conductive layer 111R, the conductive layer 111G, and the conductive layer 111B) during the processing. This can widen the range of choices of the material for the conductive layer 111. Note that the pixel electrode in the display device of one embodiment of the present invention may have a stacked-layer structure of two or more layers.

In the case of a top-emission display device, an electrode having a property of reflecting visible light (a reflective electrode) is used as the conductive layer 111. Note that in the case where the pixel electrode has a two-layer stacked structure, the conductive layer 111 may be used as a reflective electrode for a first layer, and an electrode having a property of transmitting visible light (a transparent electrode) may be used for a second layer.

In FIG. 1B, an insulating layer (also referred to as a partition, a bank, a spacer, or the like) covering the end portion of the top surface of the conductive layer 111R is not provided between the conductive layer 111R and the layer 113R. An insulating layer covering the end portion of the top surface of the conductive layer 111G is not provided between the conductive layer 111G and the layer 113G. Similarly, an insulating layer covering the end portion of the top surface of the conductive layer 111B is not provided between the conductive layer 111B and the layer 113B. Thus, the distance between adjacent light-emitting devices (light-emitting regions) can be significantly shortened. Accordingly, the display device can have a high resolution or a high definition. In addition, a mask for forming the insulating layer is not needed, which leads to a reduction in manufacturing cost of the display device.

Furthermore, light emitted from the EL layer can be extracted efficiently with a structure in which an insulating layer covering the end portion of the pixel electrode is not provided between the pixel electrode and the EL layer, i.e., a structure in which an insulating layer is not provided between the pixel electrode and the EL layer. Therefore, the display device of one embodiment of the present invention can significantly reduce the viewing angle dependence. A reduction in the viewing angle dependence leads to an increase in visibility of an image on the display device. For example, in the display device of one embodiment of the present invention, the viewing angle (the maximum angle with a certain contrast ratio maintained when the screen is seen from an oblique direction) can be greater than or equal to 100° and less than 180°, preferably greater than or equal to 150° and less than or equal to 170°. Note that the viewing angle refers to that in both the vertical direction and the horizontal direction.

The light-emitting device of this embodiment may have either a single structure (a structure including only one light-emitting unit) or a tandem structure (a structure including a plurality of light-emitting units). The light-emitting unit includes at least one light-emitting layer.

The layer 113R, the layer 113G, and the layer 113B each include at least a light-emitting layer. The layer 113R includes a light-emitting layer emitting red light, the layer 113G includes a light-emitting layer emitting green light, and the layer 113B includes a light-emitting layer emitting blue light. In other words, the layer 113R contains a light-emitting material emitting red light, the layer 113G contains a light-emitting material emitting green light, and the layer 113B contains a light-emitting material emitting blue light.

In the case of using a light-emitting device having a tandem structure, the layer 113R is preferably configured to include a plurality of light-emitting units emitting red light, the layer 113G is preferably configured to include a plurality of light-emitting units emitting green light, and the layer 113B is preferably configured to include a plurality of light-emitting units emitting blue light. A charge-generation layer (also referred to as an intermediate layer) is preferably provided between the light-emitting units.

The layer 113R, the layer 113G, and the layer 113B may each include one or more of a hole-injection layer, a hole-transport layer, a hole-blocking layer, a charge-generation layer, an electron-blocking layer, an electron-transport layer, and an electron-injection layer.

For example, the layer 113R, the layer 113G, and the layer 113B may each include a hole-injection layer, a hole-transport layer, a light-emitting layer, and an electron-transport layer in this order. In addition, an electron-blocking layer may be provided between the hole-transport layer and the light-emitting layer. In addition, a hole-blocking layer may be provided between the electron-transport layer and the light-emitting layer. Furthermore, an electron-injection layer may be provided over the electron-transport layer.

Alternatively, the layer 113R, the layer 113G, and the layer 113B may each include an electron-injection layer, an electron-transport layer, a light-emitting layer, and a hole-transport layer in this order, for example. In addition, a hole-blocking layer may be provided between the electron-transport layer and the light-emitting layer. In addition, an electron-blocking layer may be provided between the hole-transport layer and the light-emitting layer. Furthermore, a hole-injection layer may be provided over the hole-transport layer.

Thus, the layer 113R, the layer 113G, and the layer 113B each preferably include a light-emitting layer and a carrier-transport layer (an electron-transport layer or a hole-transport layer) over the light-emitting layer. Alternatively, the layer 113R, the layer 113G, and the layer 113B each preferably include a light-emitting layer and a carrier-blocking layer (a hole-blocking layer or an electron-blocking layer) over the light-emitting layer. Alternatively, the layer 113R, the layer 113G, and the layer 113B each preferably include a light-emitting layer, a carrier-blocking layer over the light-emitting layer, and a carrier-transport layer over the carrier-blocking layer. Since the surfaces of the layer 113R, the layer 113G, and the layer 113B are exposed in the fabrication process of the display device, providing one or both of the carrier-transport layer and the carrier-blocking layer over the light-emitting layer inhibits the light-emitting layer from being exposed on the outermost surface, so that damage to the light-emitting layer can be reduced.

Accordingly, the reliability of the light-emitting device can be improved.

The upper temperature limits of the compounds contained in the layer 113R, the layer 113G, and the layer 113B are each preferably higher than or equal to 100° C. and lower than or equal to 180° C., further preferably higher than or equal to 120° C. and lower than or equal to 180° C., still further preferably higher than or equal to 140° C. and lower than or equal to 180° C. For example, the glass transition points (Tg) of these compounds are each preferably higher than or equal to 100° C. and lower than or equal to 180° C., further preferably higher than or equal to 120° C. and lower than or equal to 180° C., still further preferably higher than or equal to 140° C. and lower than or equal to 180° C.

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

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

The light-emitting layer contains a light-emitting substance (also referred to as a light-emitting material, a light-emitting organic compound, a guest material, or the like) and an organic compound (also referred to as a host material or the like). Since the light-emitting layer is configured to contain more organic compound than light-emitting substance, Tg of the organic compound can be used as an indicator of the upper temperature limit of the light-emitting layer.

The layer 113R, the layer 113G, and the layer 113B may each include a first light-emitting unit, a charge-generation layer over the first light-emitting unit, and a second light-emitting unit over the charge-generation layer, for example.

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

The common layer 114 includes, for example, an electron-injection layer or a hole-injection layer. Alternatively, the common layer 114 may include a stack of an electron-transport layer and an electron-injection layer, or may include a stack of a hole-transport layer and a hole-injection layer. The common layer 114 is shared by the light-emitting device 130R, the light-emitting device 130G, and the light-emitting device 130B.

FIG. 1B illustrates an example in which the end portion of the conductive layer 111R and the end portion of the layer 113R substantially overlap with each other (their side surfaces are substantially aligned with each other) as described above. Although description is made using the conductive layer 111R and the layer 113R as an example below, the same applies to the conductive layer 111G and the layer 113G, and the conductive layer 111B and the layer 113B.

In FIG. 1B, the layer 113R and the conductive layer 111R are formed such that their end portions substantially overlap with each other. Such a structure enables the entire top surface of the conductive layer 111R to be a light-emitting region, and the aperture ratio can be easily increased as compared with a structure in which the end portion of the island-shaped EL layer is positioned inward from the end portion of the pixel electrode.

The common electrode 115 is shared by the light-emitting device 130R, the light-emitting device 130G, and the light-emitting device 130B. The common electrode 115 shared by the plurality of light-emitting devices is electrically connected to a conductive layer 123 provided in the connection portion 140 (see FIG. 12A and FIG. 12B). The conductive layer 123 is preferably formed using a conductive layer formed using the same material and in the same step as the conductive layer 111R, the conductive layer 111G, and the conductive layer 111B.

Note that FIG. 12A illustrates an example in which the common layer 114 is provided over the conductive layer 123, and the conductive layer 123 and the common electrode 115 are electrically connected to each other through the common layer 114. The common layer 114 is not necessarily provided in the connection portion 140. In FIG. 12B, the conductive layer 123 and the common electrode 115 are directly connected to each other. For example, by using a mask for specifying a film formation area (also referred to as an area mask, a rough metal mask, or the like to be distinguished from a fine metal mask), the common layer 114 can be formed in a region different from a region where the common electrode 115 is formed.

After formation of the common layer 114, the common electrode 115 can be formed successively without a process such as etching therebetween. For example, after the common layer 114 is formed in vacuum, the common electrode 115 can be formed in vacuum without being exposed to the air. In other words, the common layer 114 and the common electrode 115 can be formed consistently in vacuum. Accordingly, the lower surface of the common electrode 115 can be a clean surface, as compared to the case where the common layer 114 is not provided in the display device 100. Thus, the light-emitting device 130R, the light-emitting device 130G, and the light-emitting device 130B can be light-emitting devices with high reliability and excellent characteristics.

In FIG. 1B, a mask layer 118R is positioned over the layer 113R included in the light-emitting device 130R, a mask layer 118G is positioned over the layer 113G included in the light-emitting device 130G, and a mask layer 118B is positioned over the layer 113B included in the light-emitting device 130B. The mask layers have an opening in a portion overlapping with the light-emitting region. The mask layer 118R is a remaining part of a mask film provided in contact with the top surface of the layer 113R at the time of processing the layer 113R. Similarly, the mask layer 118G is a remaining part of a mask film provided at the time of forming the layer 113G, and the mask layer 118B is a remaining part of a mask film provided at the time of forming the layer 113B. Thus, the mask film used to protect the EL layer in fabrication of the display device may partly remain in the display device of one embodiment of the present invention. For any two or all of the mask layer 118R, the mask layer 118G, and the mask layer 118B, the same material may be used or different materials may be used. Note that the mask layer 118R, the mask layer 118G, and the mask layer 118B are sometimes collectively referred to as a mask layer 118 below.

In FIG. 1B, one end portion (an outer end portion, which is opposite to the light-emitting region) of the mask layer 118R is aligned or substantially aligned with the end portion of the conductive layer 111R and the layer 113R, and the other end portion of the mask layer 118R is positioned over the layer 113R. Here, the other end portion (an inner end portion, which is on the light-emitting region side) of the mask layer 118R preferably overlaps with the layer 113R and the conductive layer 111R. In that case, the other end portion of the mask layer 118R is easily formed over a substantially flat surface of the layer 113R. Note that the same applies to the mask layer 118G and the mask layer 118B. The mask layer 118 remains between the top surface of the EL layer processed into an island shape (the layer 113R, the layer 113G, or the layer 113B) and the insulating layer 125, for example. The mask layer will be described in detail in Embodiment 2.

In the case where end portions are aligned or substantially aligned with each other and the case where top surface shapes are the same or substantially the same, it can be said that outlines of stacked layers at least partly overlap with each other in a plan view. For example, the case of processing the upper layer and the lower layer with the use of the same mask pattern or mask patterns that are partly the same is included. Note that, in some cases, the outlines do not completely overlap with each other and the upper layer is positioned inward from the lower layer or the upper layer is positioned outward from the lower layer; such cases are also represented by the expression “end portions are substantially aligned with each other” or the expression “top surface shapes are substantially the same”.

In the light-emitting device 130R, the side surfaces of the conductive layer 111R and the layer 113R are covered with the insulating layer 125 with the sidewall insulating layer 107R_1 therebetween.

In the light-emitting device 130G, the side surfaces of the conductive layer 111G and the layer 113G are covered with the insulating layer 125 with the sidewall insulating layer 107G_1 and the sidewall insulating layer 107G_2 therebetween.

In the light-emitting device 130B, the side surfaces of the conductive layer 111B and the layer 113B are covered with the insulating layer 125 with the sidewall insulating layer 107B_1, the sidewall insulating layer 107B_2, and the sidewall insulating layer 107B_3 therebetween.

The insulating layer 127 is provided to overlap with the side surfaces of the conductive layer 111R and the layer 113R, the side surfaces of the conductive layer 111G and the layer 113G, and the side surfaces of the conductive layer 111B and the layer 113B with the sidewall insulating layer 107 (the sidewall insulating layer 107R_1, the sidewall insulating layer 107G_1, the sidewall insulating layer 107G_2, the sidewall insulating layer 107B_1, the sidewall insulating layer 107B_2, and the sidewall insulating layer 107B_3) and the insulating layer 125 therebetween.

The top surfaces of the conductive layer 111R and the layer 113R, the top surfaces of the conductive layer 111G and the layer 113G, and the top surfaces of the conductive layer 111B and the layer 113B are partly covered with the mask layer 118. The insulating layer 125 and the insulating layer 127 partly overlap with the top surfaces of the conductive layer 111R and the layer 113R, the top surfaces of the conductive layer 111G and the layer 113G, and the top surfaces of the conductive layer 111B and the layer 113B with the mask layer 118 therebetween.

The side surfaces and parts of the top surfaces of the conductive layer 111R and the layer 113R, the side surfaces and parts of the top surfaces of the conductive layer 111G and the layer 113G, and the side surfaces and parts of the top surfaces of the conductive layer 111B and the layer 113B are covered with at least one of the sidewall insulating layer 107, the mask layer 118, the insulating layer 125, and the insulating layer 127, so that the common layer 114 (or the common electrode 115) can be inhibited from being in contact with the side surfaces of the pixel electrodes (the conductive layer 111R, the conductive layer 111G, and the conductive layer 111B), the layer 113R, the layer 113G, and the layer 113B, which can inhibit short circuits in the light-emitting devices. Thus, the reliability of the light-emitting devices can be increased.

Although FIG. 1B illustrates the layer 113R, the layer 113G, and the layer 113B that have the same thickness, the present invention is not limited thereto. The layer 113R, the layer 113G, and the layer 113B may have different thicknesses. For example, the thickness is preferably set in accordance with an optical path length for intensifying light emitted from the layer 113R, the layer 113G, and the layer 113B. A microcavity structure can be achieved in this manner, and the color purity of each light-emitting device can be increased.

Note that even when the layer 113R, the layer 113G, and the layer 113B have the same thickness, providing conductive layers that have properties of transmitting visible light and have different thicknesses between the conductive layers 111 and the corresponding layers 113R, 113G, and 113B can achieve the above-described microcavity structure.

The insulating layer 125 is preferably provided to cover at least the top surface and part of the side surface of the sidewall insulating layer 107 in contact with the side surfaces of the conductive layer 111R and the layer 113R, the side surfaces of the conductive layer 111G and the layer 113G, and the side surfaces of the conductive layer 111B and the layer 113B. In addition, the insulating layer 125 is preferably provided to cover the side surfaces and the top surfaces of the sidewall insulating layers 107 that face each other in a region (a non-light-emitting region) between the adjacent light-emitting devices. The insulating layer 125 having such a structure can prevent film separation of the conductive layer 111R and the layer 113R, the conductive layer 111G and the layer 113G, and the conductive layer 111B and the layer 113B. When the insulating layer 125 is in close contact with the sidewall insulating layer 107, the effect of fixing or bonding the adjacent EL layers and the like by the insulating layer 125 can be obtained. Thus, the reliability of the light-emitting devices can be increased. The fabrication yield of the light-emitting devices can be increased.

As illustrated in FIG. 1B, the insulating layer 125 and the insulating layer 127 cover the side surfaces and parts of the top surfaces of the layer 113R, the layer 113G, and the layer 113B, whereby film separation of the EL layers can further be prevented and the reliability of the light-emitting devices can be improved. The fabrication yield of the light-emitting devices can also be improved.

In the example illustrated in FIG. 1B, a stacked-layer structure of the layer 113R, the mask layer 118R, the insulating layer 125, and the insulating layer 127 is positioned over the end portion of the conductive layer 111R. Similarly, a stacked-layer structure of the layer 113G, the mask layer 118G, the insulating layer 125, and the insulating layer 127 is positioned over the end portion of the conductive layer 111G; and a stacked-layer structure of the layer 113B, the mask layer 118B, the insulating layer 125, and the insulating layer 127 is positioned over the end portion of the conductive layer 111B.

In FIG. 1B, the end portion of the conductive layer 111R and the end portion of the layer 113R substantially overlap with each other, and the sidewall insulating layer 107R_1 is in contact with the side surfaces of the conductive layer 111R and the layer 113R. The end portion of the conductive layer 111G and the end portion of the layer 113G substantially overlap with each other, and the sidewall insulating layer 107G_1 is in contact with the side surfaces of the conductive layer 111G and the layer 113G. The sidewall insulating layer 107G_2 is in contact with the side surface of the sidewall insulating layer 107G_1 that is opposite to the side surface thereof in contact with the conductive layer 111G and the layer 113G. The end portion of the conductive layer 111B and the end portion of the layer 113B substantially overlap with each other, and the sidewall insulating layer 107B_1 is in contact with the side surfaces of the conductive layer 111B and the layer 113B. The sidewall insulating layer 107B_2 is in contact with the side surface of the sidewall insulating layer 107B_1 that is opposite to the side surface thereof in contact with the conductive layer 111B and the layer 113B. The sidewall insulating layer 107B_3 is in contact with the side surface of the sidewall insulating layer 107B_2 that is opposite to the side surface thereof in contact with the sidewall insulating layer 107B_1.

The insulating layer 125 is in contact with the side surfaces of the sidewall insulating layer 107R_1 and the sidewall insulating layer 107G_2 that face each other, in contact with the side surfaces of the sidewall insulating layer 107G_2 and the sidewall insulating layer 107B_3 that face each other, and in contact with the side surfaces of the sidewall insulating layer 107B_3 and the sidewall insulating layer 107R_1 that face each other (not illustrated).

The insulating layer 127 is provided over the insulating layer 125 to fill a depressed portion formed in the insulating layer 125. The insulating layer 127 can be configured to overlap with the side surfaces and parts of the top surfaces of the conductive layer 111R and the layer 113R, the side surfaces and parts of the top surfaces of the conductive layer 111G and the layer 113G, and the side surfaces and parts of the top surfaces of the conductive layer 111B and the layer 113B with the insulating layer 125 therebetween. The insulating layer 127 preferably covers at least part of the side surface of the insulating layer 125.

The insulating layer 125 and the insulating layer 127 can fill a space between adjacent island-shaped layers, whereby extreme unevenness of a formation surface of the layers (e.g., the carrier-injection layer and the common electrode) provided over the island-shaped layers can be reduced and the formation surface can have higher flatness. Consequently, coverage of the formation surface with the carrier-injection layer, the common electrode, and the like can be improved.

The common layer 114 and the common electrode 115 are provided over the layer 113R, the layer 113G, the layer 113B, the mask layer 118, the insulating layer 125, and the insulating layer 127. Before the insulating layer 125 and the insulating layer 127 are provided, a step is generated because of a region where the island-shaped pixel electrode and the island-shaped EL layer are provided and a region where neither the island-shaped pixel electrode nor the island-shaped EL layer is provided (a region between the light-emitting devices). In the display device of one embodiment of the present invention, the step can be eliminated with the insulating layer 125 and the insulating layer 127, and the coverage with the common layer 114 and the common electrode 115 in the region where neither the island-shaped pixel electrode nor the island-shaped EL layer is provided can be improved. Thus, connection defects caused by step disconnection of the common layer 114 and the common electrode 115 can be inhibited. In addition, an increase in electric resistance, which is caused by local thinning of the common layer 114 and the common electrode 115 due to the step, can be inhibited.

The top surface of the insulating layer 127 preferably has a shape with higher flatness, but may include a projection portion, a convex surface, a concave surface, or a depressed portion. For example, the top surface of the insulating layer 127 preferably has a smooth convex shape with high flatness.

Described next are examples of materials for the pixel electrode (the conductive layer 111), the common electrode 115, the sidewall insulating layer 107, the insulating layer 125, and the insulating layer 127 of the display device of one embodiment of the present invention.

For the conductive layer 111, a metal, an alloy, an electrically conductive compound, a mixture thereof, and the like can be used as appropriate. In the case of a top-emission display device, the conductive layer 111 corresponds to a reflective electrode of the display device. Hence, for the conductive layer 111, a material having a property of reflecting visible light is preferably used. Examples of the material include metals such as aluminum, magnesium, titanium, chromium, manganese, iron, cobalt, nickel, copper, gallium, zinc, indium, tin, molybdenum, tantalum, tungsten, palladium, gold, platinum, silver, yttrium, and neodymium, and an alloy containing any of these metals in appropriate combination. Other examples of the material include an alloy containing aluminum (an aluminum alloy), such as an alloy of aluminum, nickel, and lanthanum (Al—Ni—La), and an alloy containing silver, such as an alloy of silver and magnesium or an alloy of silver, palladium, and copper (also referred to as Ag—Pd—Cu or APC). Other examples of the material include elements belonging to Group 1 and Group 2 of the periodic table, which are not exemplified above (e.g., lithium, cesium, calcium, and strontium), rare earth metals such as europium and ytterbium, an alloy containing any of these metals in appropriate combination, and graphene.

For the common electrode 115, a metal, an alloy, an electrically conductive compound, a mixture thereof, and the like can be used as appropriate. In the case of a top-emission display device, the common electrode 115 corresponds to a transparent electrode of the display device. Thus, a material having a property of transmitting visible light is preferably used for the common electrode 115. Examples of the material include indium tin oxide (also referred to as In—Sn oxide or ITO), In—Si—Sn oxide (also referred to as ITSO), indium zinc oxide (In—Zn oxide), and In—W—Zn oxide. Note that in the case where the pixel electrode has a two-layer stacked structure, a conductive layer having a property of transmitting visible light can be provided as a transparent electrode over the conductive layer 111 corresponding to a reflective electrode, for example. In that case, the transparent electrode can be formed using the same material as the common electrode 115.

In the case of a bottom-emission display device, the conductive layer 111 corresponds to the transparent electrode of the display device, and the common electrode 115 corresponds to the reflective electrode of the display device. Hence, in the case of a bottom-emission display device, it is preferable that the aforementioned material having a property of transmitting visible light be used for the conductive layer 111 and that the aforementioned material having a property of reflecting visible light be used for the common electrode 115.

The sidewall insulating layer 107 and the insulating layer 125 can each be an insulating layer containing an inorganic material. As each of the sidewall insulating layer 107 and the insulating layer 125, an inorganic insulating film such as an oxide insulating film, a nitride insulating film, an oxynitride insulating film, or a nitride oxide insulating film can be used, for example. The sidewall insulating layer 107 and the insulating layer 125 may each have a single-layer structure or a stacked-layer structure. Examples of the oxide insulating film include a silicon oxide film, an aluminum oxide film, a magnesium oxide film, an indium-gallium-zinc oxide film, a gallium oxide film, a germanium oxide film, an yttrium oxide film, a zirconium oxide film, a lanthanum oxide film, a neodymium oxide film, a hafnium oxide film, and a tantalum oxide film. Examples of the nitride insulating film include a silicon nitride film and an aluminum nitride film. Examples of the oxynitride insulating film include a silicon oxynitride film and an aluminum oxynitride film. Examples of the nitride oxide insulating film include a silicon nitride oxide film and an aluminum nitride oxide film. In particular, aluminum oxide is preferable because it has high selectivity with respect to the EL layer in etching and has a function of protecting the EL layer in forming the insulating layer 127 which is to be described later. In particular, when an inorganic insulating film such as an aluminum oxide film, a hafnium oxide film, or a silicon oxide film formed by an atomic layer deposition (ALD) method is used as each of the sidewall insulating layer 107 and the insulating layer 125, the sidewall insulating layer 107 and the insulating layer 125 each having few pinholes and an excellent function of protecting the EL layer can be formed. The sidewall insulating layer 107 and the insulating layer 125 may each have a stacked-layer structure of a film formed by an ALD method and a film formed by a sputtering method. The sidewall insulating layer 107 and the insulating layer 125 may each have a stacked-layer structure of an aluminum oxide film formed by an ALD method and a silicon nitride film formed by a sputtering method, for example.

The sidewall insulating layer 107 and the insulating layer 125 each preferably have a function of a barrier insulating layer against at least one of water and oxygen. Alternatively, the sidewall insulating layer 107 and the insulating layer 125 each preferably have a function of inhibiting diffusion of at least one of water and oxygen. Alternatively, the sidewall insulating layer 107 and the insulating layer 125 each preferably have a function of capturing or fixing (also referred to as gettering) at least one of water and oxygen.

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

When the sidewall insulating layer 107 and the insulating layer 125 each have a function of a barrier insulating layer or a gettering function, entry of impurities (typically, at least one of water and oxygen) that would diffuse into the light-emitting devices from the outside can be inhibited. With this structure, a highly reliable light-emitting device and a highly reliable display device can be provided.

The sidewall insulating layer 107 and the insulating layer 125 each preferably have a low impurity concentration. Accordingly, degradation of the EL layer, which is caused by entry of impurities into the EL layer from the sidewall insulating layer 107 and the insulating layer 125, can be inhibited. In addition, when the impurity concentration is reduced in each of the sidewall insulating layer 107 and the insulating layer 125, a barrier property against at least one of water and oxygen can be increased. For example, it is desirable that one or both of the hydrogen concentration and the carbon concentration in each of the sidewall insulating layer 107 and the insulating layer 125 be sufficiently low.

Note that the sidewall insulating layer 107 and the insulating layer 125 can be formed using the same material as the mask layer 118B, the mask layer 118G, and the mask layer 118R. In that case, the boundaries between any of the mask layer 118B, the mask layer 118G, and the mask layer 118R and each of the sidewall insulating layer 107 and the insulating layer 125 are unclear and thus the layers cannot be distinguished from each other in some cases. Thus, in some cases, the sidewall insulating layer 107 and any of the mask layer 118B, the mask layer 118G, and the mask layer 118R are observed as one layer, and the insulating layer 125 and any of the mask layer 118B, the mask layer 118G, and the mask layer 118R are observed as one layer. In other words, in some cases, one layer is observed as being provided in contact with the side surface and part of the top surface of each of the layer 113R, the layer 113G, and the layer 113B and the insulating layer 127 is observed as covering at least part of the side surface of the one layer.

The insulating layer 127 provided over the insulating layer 125 has a function of filling extreme unevenness of the insulating layer 125, which is formed in a region between the adjacent light-emitting devices (a non-light-emitting region). In other words, the insulating layer 127 has an effect of improving the flatness of the formation surface of the common electrode 115.

As the insulating layer 127, an insulating layer containing an organic material can be suitably used. As the organic material, a photosensitive organic resin is preferably used, and for example, a photosensitive resin composite containing an acrylic resin is preferably used. Note that in this specification and the like, an acrylic resin refers not only to a polymethacrylic acid ester or a methacrylic resin, but also to all the acrylic-based polymers in a broad sense in some cases.

Alternatively, for the insulating layer 127, an acrylic resin, a polyimide resin, an epoxy resin, an imide resin, a polyamide resin, a polyimide-amide resin, a silicone resin, a siloxane resin, a benzocyclobutene-based resin, a phenol resin, precursors of these resins, or the like may be used. Alternatively, for the insulating layer 127, an organic material such as polyvinyl alcohol (PVA), polyvinyl butyral, polyvinylpyrrolidone, polyethylene glycol, polyglycerin, pullulan, water-soluble cellulose, or an alcohol-soluble polyamide resin may be used. A photoresist may be used for the photosensitive resin. As the photosensitive organic resin, either a positive material or a negative material may be used.

For the insulating layer 127, a material absorbing visible light may be used. When the insulating layer 127 absorbs light from the light-emitting device, leakage of light (stray light) from the light-emitting device to the adjacent light-emitting device through the insulating layer 127 can be inhibited. Thus, the display quality of the display device can be improved. Since no polarizing plate is required to improve the display quality, the weight and thickness of the display device can be reduced.

Examples of the material absorbing visible light include materials containing pigment of black or the like, materials containing dye, light-absorbing resin materials (e.g., polyimide), and resin materials that can be used for color filters (color filter materials). Using a resin material obtained by stacking or mixing color filter materials of two colors or three or more colors is particularly preferable, in which case the effect of blocking visible light can be enhanced. In particular, mixing color filter materials of three or more colors enables the formation of a black or nearly black resin layer.

Next, a structure of the insulating layer 127 and the vicinity thereof will be described with reference to FIG. 2A and FIG. 2B. FIG. 2A is an enlarged cross-sectional view of a region including the insulating layer 127 between the light-emitting device 130R and the light-emitting device 130G, and the vicinity of the insulating layer 127. Although the insulating layer 127 between the light-emitting device 130R and the light-emitting device 130G is described below as an example, the same applies to the insulating layer 127 between the light-emitting device 130G and the light-emitting device 130B, the insulating layer 127 between the light-emitting device 130B and the light-emitting device 130R, and the like. FIG. 2B is an enlarged view of an end portion of the insulating layer 127 over the layer 113G and the vicinity thereof illustrated in FIG. 2A. Note that the common layer 114, the common electrode 115, and the protective layer 131 are not illustrated in FIG. 2B. Although the end portion of the insulating layer 127 over the layer 113G is sometimes described below as an example, the same applies to an end portion of the insulating layer 127 over the layer 113B, an end portion of the insulating layer 127 over the layer 113R, and the like.

As illustrated in FIG. 2A, the sidewall insulating layer 107R_1 is provided in contact with the side surfaces of the conductive layer 111R, the layer 113R, and the mask layer 118R, and the sidewall insulating layer 107G_1 is provided in contact with the side surfaces of the conductive layer 111G, the layer 113G, and the mask layer 118G. The sidewall insulating layer 107G_2 is provided in contact with the side surface of the sidewall insulating layer 107G_1 that is opposite to the side surface thereof in contact with the conductive layer 111G, the layer 113G, and the mask layer 118G. The mask layer 118R is provided in contact with part of the top surface of the layer 113R, and the mask layer 118G is provided in contact with part of the top surface of the layer 113G. The insulating layer 125 is provided in contact with the top surface of the mask layer 118R, part of one side surface of the sidewall insulating layer 107R_1 (the side surface in contact with the conductive layer 111R, the layer 113R, and the mask layer 118R), the top surface of the sidewall insulating layer 107R_1, the other side surface of the sidewall insulating layer 107R_1, part of the top surface of the insulating layer 255c, the top surface of the mask layer 118G, part of one side surface of the sidewall insulating layer 107G_1 (the side surface in contact with the conductive layer 111G, the layer 113G, and the mask layer 118G), the top surface of the sidewall insulating layer 107G_2, and the side surface of the sidewall insulating layer 107G_2 that is opposite to the side surface thereof in contact with the sidewall insulating layer 107G_1. The insulating layer 125 covers parts of the top surfaces of the conductive layer 111R and the layer 113R and parts of the top surfaces of the conductive layer 111G and the layer 113G. The insulating layer 127 is provided in contact with the top surface of the insulating layer 125. The insulating layer 127 overlaps with the side surfaces and parts of the top surfaces of the conductive layer 111R and the layer 113R and the side surfaces and parts of the top surfaces of the conductive layer 111G and the layer 113G with the insulating layer 125 therebetween, and is in contact with at least part of the side surface of the insulating layer 125. The common layer 114 is provided to cover the layer 113R, the mask layer 118R, the sidewall insulating layer 107R_1, the layer 113G, the sidewall insulating layer 107G_1, the sidewall insulating layer 107G_2, the mask layer 118G, the insulating layer 125, and the insulating layer 127, and the common electrode 115 is provided over the common layer 114.

The insulating layer 127 is formed in a region between two island-shaped EL layers (e.g., a region between the layer 113R and the layer 113G in FIG. 2A). At this time, at least part of the insulating layer 127 is placed at a position interposed between an end portion of the side surface of one of the EL layers (e.g., the layer 113R in FIG. 2A) and an end portion of the side surface of the other of the EL layers (e.g., the layer 113G in FIG. 2A). Providing the insulating layer 127 in such a manner can prevent formation of a disconnected portion and a locally thinned portion in the common layer 114 and the common electrode 115 that are formed over the island-shaped EL layers and the insulating layer 127.

As illustrated in FIG. 2B, the end portion of the insulating layer 127 preferably has a tapered shape with a taper angle θ1 in the cross-sectional view of the display device. The taper angle θ1 is an angle formed by the side surface of the insulating layer 127 and the substrate surface. Note that the taper angle θ1 is not limited to the angle with the substrate surface, and may be an angle formed by the side surface of the insulating layer 127 and the top surface of the flat portion of the layer 113G or the top surface of the flat portion of the conductive layer 111G.

The taper angle θ1 of the insulating layer 127 is less than 90°, preferably less than or equal to 60°, further preferably less than or equal to 45°, still further preferably less than or equal to 20°. When the end portion of the insulating layer 127 has such a tapered shape, the common layer 114 and the common electrode 115 that are provided over the insulating layer 127 can be formed with good coverage, thereby inhibiting step disconnection, local thinning, or the like from being generated in the common layer 114 and the common electrode 115. Accordingly, the in-plane uniformity of the thicknesses of the common layer 114 and the common electrode 115 can be improved, leading to higher display quality of the display device.

As illustrated in FIG. 2A, in the cross-sectional view of the display device, the top surface of the insulating layer 127 preferably has a convex shape. The convex shape of the top surface of the insulating layer 127 is preferably a shape gently bulged toward the center. It is also preferable that the convex portion in the center portion of the top surface of the insulating layer 127 have a shape smoothly connected to a tapered portion in the end portion. When the insulating layer 127 has such a shape, the common layer 114 and the common electrode 115 can be formed with good coverage over the entire insulating layer 127.

As illustrated in FIG. 2B, the end portion of the insulating layer 127 is preferably positioned outward from the end portion of the insulating layer 125. In that case, unevenness of the formation surface of the common layer 114 and the common electrode 115 can be reduced and coverage of the formation surface with the common layer 114 and the common electrode 115 can be improved.

As illustrated in FIG. 2B, the end portion of the insulating layer 125 preferably has a tapered shape with a taper angle θ2 in the cross-sectional view of the display device. The taper angle θ2 is an angle formed by the side surface of the insulating layer 125 and the substrate surface. Note that the taper angle θ2 is not limited to the angle with the substrate surface, and may be an angle formed by the side surface of the insulating layer 125 and the top surface of the flat portion of the layer 113G or the top surface of the flat portion of the conductive layer 111G.

The taper angle θ2 of the insulating layer 125 is less than 90°, preferably less than or equal to 60°, further preferably less than or equal to 45°, still further preferably less than or equal to 20°.

As illustrated in FIG. 2B, the end portion of the mask layer 118G preferably has a tapered shape with a taper angle θ3 in the cross-sectional view of the display device. The taper angle θ3 is an angle formed by the side surface of the mask layer 118G and the substrate surface. Note that the taper angle θ3 is not limited to the angle with the substrate surface, and may be an angle formed by the side surface of the mask layer 118G and the top surface of the flat portion of the layer 113G or the top surface of the flat portion of the conductive layer 111G.

The taper angle θ3 of the mask layer 118G is less than 90°, preferably less than or equal to 60°, further preferably less than or equal to 45°, still further preferably less than or equal to 20°. When the mask layer 118G has such a tapered shape, the common layer 114 and the common electrode 115 that are provided over the mask layer 118G can be formed with good coverage.

The end portion of the mask layer 118R and the end portion of the mask layer 118G are each preferably positioned outward from the end portion of the insulating layer 125. In that case, unevenness of the formation surface of the common layer 114 and the common electrode 115 can be reduced and coverage of the formation surface with the common layer 114 and the common electrode 115 can be improved.

Although the details will be described in Embodiment 2, when the insulating layer 125 and the mask layer 118 are collectively etched, the insulating layer 125 and the mask layer 118 below the end portion of the insulating layer 127 are eliminated by side etching and accordingly a cavity is formed in some cases. The cavity causes unevenness in the formation surface of the common layer 114 and the common electrode 115, so that step disconnection is likely to occur in the common layer 114 and the common electrode 115. Thus, the etching treatment is performed in two separate steps with heat treatment performed between the two etching steps, whereby even when a cavity is formed by the first etching treatment, the cavity can be filled with the insulating layer 127 deformed by the heat treatment. In addition, since the second etching treatment etches a thin film, the amount of side etching is small and thus a cavity is not easily formed, and even if a cavity is formed, it can be extremely small. Thus, generation of unevenness in the formation surface of the common layer 114 and the common electrode 115 can be inhibited and accordingly step disconnection of the common layer 114 and the common electrode 115 can be inhibited. Since the etching treatment is performed twice as described above, the taper angle θ2 and the taper angle θ3 might be different angles. The taper angle θ2 and the taper angle θ3 may be the same angle. Each of the taper angle θ2 and the taper angle θ3 might be an angle smaller than the taper angle θ1.

The insulating layer 127 covers at least part of the side surface of the mask layer 118R and at least part of the side surface of the mask layer 118G in some cases. For example, FIG. 2B illustrates an example in which the insulating layer 127 touches and covers an inclined surface positioned at an end portion of the mask layer 118G which is formed by the first etching treatment, and an inclined surface positioned at an end portion of the mask layer 118G which is formed by the second etching treatment is exposed. In some cases, these two inclined surfaces can be distinguished from each other depending on their different taper angles. There might be almost no difference between the taper angles formed at the side surfaces by the two etching steps; in this case, the inclined surfaces cannot be distinguished from each other.

FIG. 3A and FIG. 3B illustrate an example in which the insulating layer 127 covers the entire side surface of the mask layer 118R and the entire side surface of the mask layer 118G. Specifically, in FIG. 3B, the insulating layer 127 touches and covers both of the two inclined surfaces. This is preferable because unevenness of the formation surface of the common layer 114 and the common electrode 115 can be further reduced. FIG. 3B illustrates an example in which the end portion of the insulating layer 127 is positioned outward from the end portion of the mask layer 118G. As illustrated in FIG. 2B, the end portion of the insulating layer 127 may be positioned inward from the end portion of the mask layer 118G, or may be aligned or substantially aligned with the end portion of the mask layer 118G. As illustrated in FIG. 3B, the insulating layer 127 is in contact with the layer 113G in some cases.

Also in FIG. 3B, the taper angle θ1 to the taper angle θ3 are preferably within the above range.

FIG. 4A and FIG. 4B illustrate examples in which the side surface of the insulating layer 127 has a concave shape (also referred to as a narrowed portion, a depressed portion, a dent, a hollow, or the like). Depending on the materials and the formation conditions (e.g., heating temperature, heating time, and heating atmosphere) of the insulating layer 127, the side surface of the insulating layer 127 has a concave shape in some cases.

FIG. 4A illustrates an example in which the insulating layer 127 covers part of the side surface of the mask layer 118R and part of the side surface of the mask layer 118G, and the other part of the side surface of the mask layer 118R and the other part of the side surface of the mask layer 118G are exposed. FIG. 4B illustrates an example in which the insulating layer 127 touches and covers the entire side surface of the mask layer 118R and the entire side surface of the mask layer 118G.

As illustrated in FIG. 2 to FIG. 4, one end portion of the insulating layer 127 preferably overlaps with the top surface of the conductive layer 111R and the other end portion of the insulating layer 127 preferably overlaps with the top surface of the conductive layer 111G. Such a structure enables the end portion of the insulating layer 127 to be formed over substantially flat regions of the layer 113R and the layer 113G. This makes it relatively easy to form a tapered shape in each of the insulating layer 127, the insulating layer 125, and the mask layer 118. In addition, film separation of the conductive layer 111R, the conductive layer 111G, the layer 113R, and the layer 113G can be inhibited. Meanwhile, a portion where the top surface of the conductive layer 111 and the insulating layer 127 overlap with each other is preferably smaller because the light-emitting region of the light-emitting device can be wider and the aperture ratio can be higher.

Note that the insulating layer 127 does not necessarily overlap with the top surface of the conductive layer 111. As illustrated in FIG. 5A, the insulating layer 127 does not necessarily overlap with the top surface of the conductive layer 111, and one end portion of the insulating layer 127 may overlap with the side surface of the conductive layer 111R and the other end portion of the insulating layer 127 may overlap with the side surface of the conductive layer 111G. As illustrated in FIG. 5B, the insulating layer 127 does not necessarily overlap with the conductive layer 111, and may be provided in a region interposed between the conductive layer 111R and the conductive layer 111G. Note that in FIG. 5A and FIG. 5B, the insulating layer 125 does not include regions overlapping with the top surfaces of the layer 113R and the layer 113G. Thus, unlike in FIG. 2 to FIG. 4, the mask layer 118R positioned between the insulating layer 125 and the layer 113R and the mask layer 118G positioned between the insulating layer 125 and the layer 113G are not included in FIG. 5A and FIG. 5B. Even such a structure can reduce unevenness of the formation surface of the common layer 114 and the common electrode 115 and improve the coverage of the formation surface with the common layer 114 and the common electrode 115, as compared with a structure in which the insulating layer 125 and the insulating layer 127 are not provided.

As illustrated in FIG. 6A, the top surface of the insulating layer 127 may have a flat portion in a cross-sectional view of the display device.

As illustrated in FIG. 6B, the top surface of the insulating layer 127 may have a concave shape in a cross-sectional view of the display device. In FIG. 6B, the top surface of the insulating layer 127 has a shape that is gently bulged toward the center, i.e., includes a convex surface, and has a shape that is recessed in the center and its vicinity, i.e., includes a concave surface. In FIG. 6B, the convex portion of the top surface of the insulating layer 127 has a shape smoothly connected to the tapered portion in the end portion. Even when the insulating layer 127 has such a shape, the common layer 114 and the common electrode 115 can be formed with good coverage over the entire insulating layer 127.

A structure in which the insulating layer 127 includes a concave surface in its center portion as illustrated in FIG. 6B can be obtained by a light exposure method using a multi-tone mask (typically, a half-tone mask or a gray-tone mask). A multi-tone mask is a mask capable of light exposure of three light-exposure levels to provide an exposed portion, a half-exposed portion, and an unexposed portion, and is a light-exposure mask through which light is transmitted to have a plurality of intensities. The insulating layer 127 including regions with a plurality of (typically two kinds of) thicknesses can be formed with one photomask (one light exposure and development process).

Note that a method for forming a concave surface in the center portion of the insulating layer 127 is not limited to the above method. For example, an exposed portion and a half-exposed portion may be formed separately with the use of two photomasks. Alternatively, the viscosity of the resin material used for the insulating layer 127 may be adjusted; specifically, the viscosity of the material used for the insulating layer 127 may be less than or equal to 10 cP, preferably greater than or equal to 1 cP and less than or equal to 5 cP.

Although not illustrated, the concave surface in the center portion of the insulating layer 127 is not necessarily continuous, and may be disconnected in a region between adjacent light-emitting devices (a non-light-emitting region). In that case, part of the insulating layer 127 in the center portion of the insulating layer 127 illustrated in FIG. 6B is eliminated, so that the surface of the insulating layer 125 is exposed. In the case of such a structure, the common layer 114 and the common electrode 115 are formed to have shapes covering the exposed portion of the surface of the insulating layer 125.

As described above, in the structures illustrated in FIG. 2 to FIG. 6, providing the insulating layer 127, the insulating layer 125, the mask layer 118R, and the mask layer 118G enables the common layer 114 and the common electrode 115 to be formed with good coverage from the substantially flat region of the layer 113R to the substantially flat region of the layer 113G. It is also possible to prevent formation of a disconnected portion and a locally thinned portion in the common layer 114 and the common electrode 115. This can inhibit the common layer 114 and the common electrode 115 between light-emitting devices from having connection defects due to the disconnected portion and an increased electric resistance due to the locally thinned portion. Thus, the display quality of the display device of one embodiment of the present invention can be improved.

The protective layer 131 is preferably provided over the light-emitting device 130R, the light-emitting device 130G, and the light-emitting device 130B. Providing the protective layer 131 can improve the reliability of the light-emitting device. The protective layer 131 may have a single-layer structure or a stacked-layer structure of two or more layers.

There is no limitation on the conductivity of the protective layer 131. As the protective layer 131, at least one type of insulating films, semiconductor films, and conductive films can be used.

The protective layer 131 including an inorganic film can inhibit degradation of the light-emitting device by preventing oxidation of the common electrode 115 and inhibiting entry of impurities (e.g., moisture and oxygen) into the light-emitting device, for example; thus, the reliability of the display device can be improved.

As the protective layer 131, an inorganic insulating film such as an oxide insulating film, a nitride insulating film, an oxynitride insulating film, or a nitride oxide insulating film can be used, for example. Specific examples of these inorganic insulating films are as listed in the description of the insulating layer 125. In particular, the protective layer 131 preferably includes a nitride insulating film or a nitride oxide insulating film, and further preferably includes a nitride insulating film.

As the protective layer 131, an inorganic film containing In—Sn oxide (also referred to as ITO), In—Zn oxide, Ga—Zn oxide, Al—Zn oxide, indium gallium zinc oxide (In—Ga—Zn oxide, also referred to as IGZO), or the like can also be used. The inorganic film preferably has high resistance, specifically, higher resistance than the common electrode 115. The inorganic film may further contain nitrogen.

When light emitted from the light-emitting device is extracted through the protective layer 131, the protective layer 131 preferably has a high visible-light-transmitting property. For example, ITO, IGZO, and aluminum oxide are preferable because they are inorganic materials having a high visible-light-transmitting property.

The protective layer 131 can employ, for example, a stacked-layer structure of an aluminum oxide film and a silicon nitride film over the aluminum oxide film, or a stacked-layer structure of an aluminum oxide film and an IGZO film over the aluminum oxide film. Such a stacked-layer structure can inhibit entry of impurities (e.g., water and oxygen) into the EL layer.

Furthermore, the protective layer 131 may include an organic film. For example, the protective layer 131 may include both an organic film and an inorganic film. Examples of an organic material that can be used for the protective layer 131 include organic insulating materials that can be used for the insulating layer 127.

The protective layer 131 may have a stacked structure of two layers which are formed by different film formation methods. Specifically, the first layer of the protective layer 131 may be formed by an ALD method, and the second layer of the protective layer 131 may be formed by a sputtering method.

A light-blocking layer may be provided on the surface of the substrate 120 on the resin layer 122 side. Moreover, a variety of optical members can be provided on the outer surface of the substrate 120. Examples of optical members include a polarizing plate, a retardation plate, a light diffusion layer (e.g., a diffusion film), an anti-reflective layer, and a light-condensing film. Furthermore, a surface protective layer such as an antistatic film inhibiting the attachment of dust, a water repellent film inhibiting the attachment of stain, a hard coat film inhibiting generation of a scratch caused by the use, or an impact-absorbing layer may be provided on the outer surface of the substrate 120. For example, it is preferable to provide, as the surface protective layer, a glass layer or a silica layer (SiO_x layer) because the surface contamination and generation of a scratch can be inhibited. For the surface protective layer, DLC (diamond-like carbon), aluminum oxide (AlO_x), a polyester-based material, a polycarbonate-based material, or the like may be used. For the surface protective layer, a material having a high transmittance with respect to visible light is preferably used. For the surface protective layer, a material with high hardness is preferably used.

For the substrate 120, glass, quartz, ceramics, sapphire, a resin, a metal, an alloy, a semiconductor, or the like can be used. For the substrate through which light from the light-emitting device is extracted, a material that transmits the light is used. When a flexible material is used for the substrate 120, the flexibility of the display device can be increased and a flexible display can be provided. Furthermore, a polarizing plate may be used as the substrate 120.

For the substrate 120, it is possible to use polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), a polyacrylonitrile resin, an acrylic resin, a polyimide resin, a polymethyl methacrylate resin, a polycarbonate (PC) resin, a polyethersulfone (PES) resin, polyamide resins (e.g., nylon and aramid), a polysiloxane resin, a cycloolefin resin, a polystyrene resin, a polyamide-imide resin, a polyurethane resin, a polyvinyl chloride resin, a polyvinylidene chloride resin, a polypropylene resin, a polytetrafluoroethylene (PTFE) resin, an ABS resin, cellulose nanofiber, and the like. Glass that is thin enough to have flexibility may be used as the substrate 120.

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

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

Examples of a highly optically isotropic film include a triacetyl cellulose (TAC, also referred to as cellulose triacetate) film, a cycloolefin polymer (COP) film, a cycloolefin copolymer (COC) film, and an acrylic film.

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

For the resin layer 122, a variety of curable adhesives such as a photocurable adhesive like an ultraviolet curable adhesive, a reactive curable adhesive, a thermosetting adhesive, and an anaerobic adhesive can be used. Examples of these adhesives include an epoxy resin, an acrylic resin, a silicone resin, a phenol resin, a polyimide resin, an imide resin, a PVC (polyvinyl chloride) resin, a PVB (polyvinyl butyral) resin, and an EVA (ethylene vinyl acetate) resin. In particular, a material with low moisture permeability, such as an epoxy resin, is preferable. A two-liquid-mixture-type resin may be used. An adhesive sheet or the like may be used.

FIG. 7A illustrates a variation example of FIG. 1B. In the structure example illustrated in FIG. 7A, the light-emitting device 130R includes a conductive layer 116R over the conductive layer 111R, the light-emitting device 130G includes a conductive layer 116G over the conductive layer 111G, and the light-emitting device 130B includes a conductive layer 116B over the conductive layer 111B. The end portion of the conductive layer 116R is substantially aligned with the end portion of the conductive layer 111R, the end portion of the conductive layer 116G is substantially aligned with the end portion of the conductive layer 111G, and the end portion of the conductive layer 116B is substantially aligned with the end portion of the conductive layer 111B. To the other structures, the structure example illustrated in FIG. 1B can be applied.

In the structure example illustrated in FIG. 7A, the conductive layer 111R and the conductive layer 116R can be regarded as a pixel electrode of the light-emitting device 130R, the conductive layer 111G and the conductive layer 116G can be regarded as a pixel electrode of the light-emitting device 130G, and the conductive layer 111B and the conductive layer 116B can be regarded as a pixel electrode of the light-emitting device 130B. That is, in the structure example illustrated in FIG. 7A, the light-emitting device 130R, the light-emitting device 130G, and the light-emitting device 130B can each be regarded as including a pixel electrode having a two-layer stacked structure.

In the case of a top-emission display device, it is preferable that an electrode having a property of reflecting visible light (a reflective electrode) be used as the conductive layer 111R, the conductive layer 111G, and the conductive layer 111B, and that an electrode having a property of transmitting visible light (a transparent electrode) be used as the conductive layer 116R, the conductive layer 116G, and the conductive layer 116B. For example, the conductive layer 116R, the conductive layer 116G, and the conductive layer 116B can be formed using any of the materials that can be used for the common electrode 115.

Note that the structure of the display device of one embodiment of the present invention is not limited to the above, and the light-emitting device 130R, the light-emitting device 130G, and the light-emitting device 130B may each include a pixel electrode having a stacked-layer structure of three or more layers of the conductive layer 111 (the conductive layer 111R, the conductive layer 111G, or the conductive layer 111B), the conductive layer 116 (the conductive layer 116R, the conductive layer 116G, or the conductive layer 116B), and another conductive layer. The number of conductive layers included in the pixel electrode may differ between the light-emitting devices.

As illustrated in FIG. 7B and FIG. 7C, the conductive layer 111 (the conductive layer 111R, the conductive layer 111G, or the conductive layer 111B) and the conductive layer 116 (the conductive layer 116R, the conductive layer 116G, or the conductive layer 116B) may each have a stacked-layer structure.

FIG. 7B illustrates a structure example of the pixel electrode in which the conductive layer 111 has a three-layer structure and the conductive layer 116 has a single-layer structure. For example, a three-layer structure of a titanium film, an aluminum film, and a titanium film is preferably used for the conductive layer 111, and an oxide conductive layer (e.g., In—Si—Sn oxide (also referred to as ITSO)) is preferably used as the conductive layer 116. An aluminum film is suitable for a reflective electrode because of its high reflectivity. However, when aluminum and the oxide conductive layer are in contact with each other, electrochemical corrosion might occur. For this reason, a titanium film is preferably provided between the aluminum film and the oxide conductive layer.

FIG. 7C illustrates a structure example of the pixel electrode in which the conductive layer 111 has a three-layer structure and the conductive layer 116 has a two-layer structure. For example, a three-layer structure of a titanium film, an aluminum film, and a titanium film is preferably used for the conductive layer 111, and a two-layer structure of a titanium film and an oxide conductive layer (e.g., In—Si—Sn oxide (also referred to as ITSO)) is preferably used for the conductive layer 116.

The structure examples of the pixel electrode are not limited to those illustrated in FIG. 7B and FIG. 7C. In the display device of one embodiment of the present invention, the conductive layer 111 may have a stacked-layer structure of four or more layers, and the conductive layer 116 may have a stacked-layer structure of three or more layers.

FIG. 8A to FIG. 8C each illustrate an example of a display device that is different from the display device illustrated in FIG. 1B in the structures of the sidewall insulating layers.

The display device illustrated in FIG. 8A is an example in which the side surface of the light-emitting device 130R is not provided with a sidewall insulating layer and the side surface of the light-emitting device 130G and the side surface of the light-emitting device 130B are each provided with a sidewall insulating layer. Differences from the display device illustrated in FIG. 1B are that one sidewall insulating layer (the sidewall insulating layer 107G_1) is in contact with the side surface of the light-emitting device 130G and two sidewall insulating layers (the sidewall insulating layer 107B_1 and the sidewall insulating layer 107B_2) are in contact with the side surface of the light-emitting device 130B.

Note that the display device of one embodiment of the present invention may have a structure in which the side surface of the light-emitting device 130R is provided with two sidewall insulating layers (the sidewall insulating layer 107R_1 and a sidewall insulating layer 107R_2), the side surface of the light-emitting device 130G is not provided with a sidewall insulating layer, and the side surface of the light-emitting device 130B is provided with one sidewall insulating layer (the sidewall insulating layer 107B_1). Alternatively, the display device of one embodiment of the present invention may have a structure in which the side surface of the light-emitting device 130R is provided with one sidewall insulating layer (the sidewall insulating layer 107R_1), the side surface of the light-emitting device 130G is provided with two sidewall insulating layers (the sidewall insulating layer 107G_1 and the sidewall insulating layer 107G_2), and the side surface of the light-emitting device 130B is not provided with a sidewall insulating layer.

The display device illustrated in FIG. 8B is an example in which the side surfaces of the light-emitting device 130R and the light-emitting device 130G are not provided with sidewall insulating layers and only the side surface of the light-emitting device 130B is provided with a sidewall insulating layer. A difference from the display device illustrated in FIG. 1B is that only one sidewall insulating layer (the sidewall insulating layer 107B_1) is in contact with the side surface of the light-emitting device 130B.

Note that the display device of one embodiment of the present invention may have a structure in which the side surfaces of the light-emitting device 130G and the light-emitting device 130B are not provided with sidewall insulating layers and only the side surface of the light-emitting device 130R is provided with a sidewall insulating layer (the sidewall insulating layer 107R_1). Alternatively, the display device of one embodiment of the present invention may have a structure in which the side surfaces of the light-emitting device 130B and the light-emitting device 130R are not provided with sidewall insulating layers and only the side surface of the light-emitting device 130G is provided with a sidewall insulating layer (the sidewall insulating layer 107G_1).

The display device illustrated in FIG. 8C is an example in which the side surfaces of the light-emitting device 130R, the light-emitting device 130G, and the light-emitting device 130B are not provided with sidewall insulating layers.

As in the display devices illustrated in FIG. 8A to FIG. 8C, a structure may be employed in which the side surface of at least one of the light-emitting devices is not provided with a sidewall insulating layer. Since the side surfaces of the light-emitting devices are covered with the insulating layer 125 even in such a structure, generation of a defect such as degradation of the characteristics of the light-emitting devices caused by entry of impurities or the like from the outside into the end portions of the conductive layer 111 (the conductive layer 111R, the conductive layer 111G, and the conductive layer 111B) and the layer 113 (the layer 113R, the layer 113G, and the layer 113B) can be inhibited regardless of the presence of the sidewall insulating layers.

As illustrated in FIG. 9A to FIG. 9C, lenses 133 may be provided in the display device. The lenses 133 can be provided to overlap with light-emitting devices.

FIG. 9A and FIG. 9B each illustrate an example in which the lenses 133 are provided over the light-emitting device 130R, the light-emitting device 130G, and the light-emitting device 130B with the protective layer 131 therebetween. The lenses 133 are preferably provided to overlap with the light-emitting devices. In the case where the lenses 133 are provided and the lenses 133 have a higher refractive index than the resin layer 122, light emitted from the light-emitting devices can be sometimes condensed as compared to the case where the lenses 133 are not provided. When the lenses 133 are directly formed over the substrate provided with the light-emitting devices, the accuracy of positional alignment of the light-emitting devices and the lenses 133 can be improved.

FIG. 9C illustrates an example in which the substrate 120 provided with the lenses 133 is bonded onto the protective layer 131 with the resin layer 122. By providing the lenses 133 for the substrate 120, the heat treatment temperature in the formation step of the lenses 133 can be increased.

Although FIG. 9B illustrates an example in which a layer having a planarization function is used as the protective layer 131, the protective layer 131 does not necessarily have a planarization function as illustrated in FIG. 9A and FIG. 9C. For example, the protective layer 131 can have a flat top surface when formed using an organic film. Alternatively, the protective layer 131 illustrated in FIG. 9A and FIG. 9C can be formed using an inorganic film, for example.

The lens 133 is preferably a lens that has a convex surface and a flat surface on the surface opposite to the convex surface (also referred to as a plano-convex lens). The lens 133 may include a convex surface facing either the substrate 120 side or the light-emitting device side. In view of the easiness of fabrication, the lens 133 provided on the light-emitting device side preferably includes a convex surface facing the substrate 120 side as illustrated in FIG. 9A and FIG. 9B. Meanwhile, the lens 133 provided on the substrate 120 side preferably includes a convex surface facing the light-emitting device side as illustrated in FIG. 9C.

The lens 133 can be formed using at least one of an inorganic material and an organic material. For example, a material containing a resin can be used for the lens. Moreover, a material containing at least one of an oxide and a sulfide can be used for the lens. As described above, the lens 133 is preferably formed using a material having a higher refractive index than the resin layer 122. As the lens 133, a microlens array can be used, for example. The lens 133 may be directly formed over the substrate or the light-emitting device; alternatively, the lens 133 separately formed may be bonded thereto.

As illustrated in FIG. 10A and FIG. 10B, a coloring layer may be provided in the display device. For example, a coloring layer 132R transmitting red light may be provided to overlap with the red-light-emitting device 130R, a coloring layer 132G transmitting green light may be provided to overlap with the green-light-emitting device 130G, and a coloring layer 132B transmitting blue light may be provided to overlap with the blue-light-emitting device 130B. For example, light with unnecessary wavelengths emitted from the red-light-emitting device 130R can be blocked by the coloring layer 132R transmitting red light. Such a structure can further increase the color purity of light emitted from each of the light-emitting devices. Although the red-light-emitting device is described above, the same effect is obtained also in the case of the combination of the green-light-emitting device 130G and the coloring layer 132G and the combination of the blue-light-emitting device 130B and the coloring layer 132B.

Providing the coloring layer so as to overlap with the light-emitting device is preferable because external light reflection can be greatly reduced. When the light-emitting device has a microcavity structure, external light reflection can be further reduced. As described above, when one, preferably both of the coloring layer and the microcavity structure are employed, external light reflection can be sufficiently reduced even without using an optical member such as a circular polarizing plate for the display device. When a circular polarizing plate is not used for the display device, decay of light emission from the light-emitting device can be inhibited and thus the outcoupling efficiency of the light-emitting device can be increased. Thus, the power consumption of the display device can be reduced.

It is also preferable that coloring layers of different colors include a region where they overlap with each other. The region where the coloring layers of different colors overlap with each other can function as a light-blocking layer. This can further reduce external light reflection.

FIG. 10A illustrates an example in which the coloring layer 132R, the coloring layer 132G, and the coloring layer 132B are respectively provided over the light-emitting device 130R, the light-emitting device 130G, and the light-emitting device 130B with the protective layer 131 therebetween. The coloring layer 132R, the coloring layer 132G, and the coloring layer 132B are directly formed over the substrate provided with the light-emitting devices, whereby the accuracy of positional alignment of the light-emitting devices and the coloring layers can be improved. Reducing the distance between the light-emitting devices and the coloring layers is preferable because color mixing can be inhibited and the viewing angle characteristics can be improved.

As illustrated in FIG. 10A, the coloring layer is preferably provided over the protective layer 131 having a planarization function. When the coloring layer is formed over a surface with high planarity, unevenness that depends on a formation surface can be inhibited from being formed on the coloring layer. Accordingly, part of light emitted from the light-emitting device can be inhibited from being reflected irregularly by unevenness of the coloring layer, so that the display quality of the display device can be improved. The protective layer 131 preferably includes an inorganic insulating film over the common electrode 115 and an organic insulating film over the inorganic insulating film, for example.

FIG. 10B illustrates an example in which the substrate 120 provided with the coloring layer 132R, the coloring layer 132G, and the coloring layer 132B is bonded onto the protective layer 131 with the resin layer 122. The coloring layer 132R, the coloring layer 132G, and the coloring layer 132B are provided on the substrate 120, whereby the heat treatment temperature in the forming process of them can be increased.

As illustrated in FIG. 11A to FIG. 11C, both coloring layers and lenses may be provided in the display device.

FIG. 11A illustrates an example in which the coloring layer 132R, the coloring layer 132G, and the coloring layer 132B are respectively provided over the light-emitting device 130R, the light-emitting device 130G, and the light-emitting device 130B with the protective layer 131 therebetween, an insulating layer 134 is provided over the coloring layer 132R, the coloring layer 132G, and the coloring layer 132B, and the lenses 133 are provided over the insulating layer 134 so as to overlap with the light-emitting devices. The coloring layer 132R, the coloring layer 132G, the coloring layer 132B, and the lenses 133 are directly formed over the substrate provided with the light-emitting devices, whereby the accuracy of positional alignment of the light-emitting devices and the coloring layers or the lenses 133 can be improved.

For the insulating layer 134, one or both of an inorganic insulating film and an organic insulating film can be used. For example, any of the materials that can be used for the protective layer 131 can be used for the insulating layer 134. The insulating layer 134 may have either a single-layer structure or a stacked-layer structure. Light emitted from the light-emitting device is extracted through the insulating layer 134, so that the insulating layer 134 preferably has a high visible-light-transmitting property.

In FIG. 11A, light emitted from the light-emitting devices passes through the coloring layers and then passes through the lenses 133 to be extracted to the outside of the display device. Reducing the distance between the light-emitting devices and the coloring layers is preferable because color mixing can be inhibited and the viewing angle characteristics can be improved. Note that the lenses 133 may be provided over the light-emitting devices and the coloring layers may be provided over the lenses 133.

FIG. 11B illustrates an example in which the substrate 120 provided with the coloring layer 132R, the coloring layer 132G, the coloring layer 132B, and the lenses 133 is bonded onto the protective layer 131 with the resin layer 122. The substrate 120 is provided with the coloring layer 132R, the coloring layer 132G, the coloring layer 132B, and the lenses 133, whereby the heat treatment temperature in the forming process of them can be increased.

In the example illustrated in FIG. 11B, the coloring layer 132R, the coloring layer 132G, and the coloring layer 132B are provided in contact with the substrate 120, the insulating layer 134 is provided in contact with the coloring layer 132R, the coloring layer 132G, and the coloring layer 132B, and the lenses 133 are provided in contact with the insulating layer 134.

In FIG. 11B, light emitted from the light-emitting devices passes through the lenses 133 and then passes through the coloring layers to be extracted to the outside of the display device. Note that the lenses 133 may be provided in contact with the substrate 120, the insulating layer 134 may be provided in contact with the lenses 133, and the coloring layers may be provided in contact with the insulating layer 134. In that case, light emitted from the light-emitting devices passes through the coloring layers and then passes through the lenses 133 to be extracted to the outside of the display device. Note that as illustrated in FIG. 11A and FIG. 11B, it is preferable that a region where the coloring layers of two colors overlap with each other be provided between the adjacent lenses 133. Providing a region where coloring layers of different colors overlap with each other can inhibit color mixture of light emitted from the light-emitting devices.

FIG. 11C illustrates an example in which the lenses 133 are provided over the light-emitting device 130R, the light-emitting device 130G, and the light-emitting device 130B with the protective layer 131 therebetween so as to overlap with the light-emitting devices, and the substrate 120 provided with the coloring layer 132R, the coloring layer 132G, and the coloring layer 132B is bonded onto the lenses 133 and the protective layer 131 with the resin layer 122.

Unlike in FIG. 11C, the lens 133 may be provided over the substrate 120 and the coloring layer may be formed directly over the protective layer 131. In this manner, one of the lens and the coloring layer may be provided over the protective layer 131 and the other may be provided over the substrate 120.

Although FIG. 11A illustrates an example in which a layer having a planarization function is used as the protective layer 131, the protective layer 131 does not necessarily have a planarization function as illustrated in FIG. 11B and FIG. 11C. For example, the protective layer 131 can have a flat top surface as illustrated in FIG. 11A when formed using an organic film. The protective layer 131 illustrated in FIG. 11B and FIG. 11C can be formed using an inorganic film, for example.

FIG. 13A illustrates a top view of the display device 100 different from that in FIG. 1A. The pixels 110 illustrated in FIG. 13A are each composed of four subpixels: the subpixel 11R, the subpixel 11G, the subpixel 11B, and a subpixel 11S.

The subpixel 11R, the subpixel 11G, the subpixel 11B, and the subpixel 11S can be configured to include light-emitting devices emitting light of different colors. The subpixel 11R, the subpixel 11G, the subpixel 11B, and the subpixel 11S are subpixels of four colors of R, G, B, and W, subpixels of four colors of R, G, B, and Y, or subpixels of four types of R, G, B, and IR, for example.

The display device of one embodiment of the present invention may include a light-receiving device in the pixel.

Three of the four subpixels included in the pixel 110 illustrated in FIG. 13A may each be configured to include a light-emitting device and the other one may be configured to include a light-receiving device.

For example, a pn or pin photodiode can be used as the light-receiving device. The light-receiving device functions as a photoelectric conversion device (also referred to as a photoelectric conversion element) that detects light entering the light-receiving device and generates electric charge. The amount of electric charge generated from the light-receiving device depends on the amount of light entering the light-receiving device.

The light-receiving device can detect one or both of visible light and infrared light. In the case of detecting visible light, for example, one or more of blue light, violet light, bluish violet light, green light, yellowish green light, yellow light, orange light, red light, and the like can be detected. The infrared light is preferably detected because an object can be detected even in a dark place.

It is particularly preferable to use an organic photodiode including a layer containing an organic compound as the light-receiving device. An organic photodiode, which is easily made thin, lightweight, and large in area and has a high degree of freedom for shape and design, can be used for a variety of display devices.

In one embodiment of the present invention, an organic EL device is used as the light-emitting device, and an organic photodiode is used as the light-receiving device. The organic EL device and the organic photodiode can be formed over the same substrate. Thus, the organic photodiode can be incorporated in the display device including the organic EL device.

The light-receiving device is driven by application of reverse bias between the pixel electrode and the common electrode, whereby light entering the light-receiving device can be detected and electric charge can be generated and extracted as current.

A fabrication method similar to that for the light-emitting device can be employed for the light-receiving device. An island-shaped active layer (also referred to as a photoelectric conversion layer) included in the light-receiving device is formed not by using a fine metal mask but by processing a film to be the active layer formed on the entire surface; thus, the island-shaped active layer can be formed to have a uniform thickness. Moreover, providing the mask layer over the active layer can reduce damage to the active layer in the fabrication process of the display device, resulting in an improvement in reliability of the light-receiving device.

Embodiment 6 can be referred to for the structure and the materials of the light-receiving device.

FIG. 13B illustrates a cross-sectional view along the dashed-dotted line X3-X4 in FIG. 13A. FIG. 1B can be referred to for a cross-sectional view along the dashed-dotted line X1-X2 in FIG. 13A, and FIG. 12A or FIG. 12B can be referred to for a cross-sectional view along the dashed-dotted line Y1-Y2.

As illustrated in FIG. 13B, in the display device 100, insulating layers (the insulating layer 255a, the insulating layer 255b, and the insulating layer 255c) are provided over the layer 101, the light-emitting device 130R and a light-receiving device 150 are provided over the insulating layers, the protective layer 131 is provided to cover the light-emitting device 130R and the light-receiving device 150, and these structures are bonded to the substrate 120 with the resin layer 122. In a region between the light-emitting device 130R and the light-receiving device 150 adjacent to each other, the insulating layer 125 and the insulating layer 127 over the insulating layer 125 are provided.

FIG. 13B illustrates an example in which light is emitted from the light-emitting device 130R to the substrate 120 side and light enters the light-receiving device 150 from the substrate 120 side (see light Lem and light Lin).

The structure of the light-emitting device 130R is as described above.

The light-receiving device 150 includes a conductive layer 111S over the insulating layer 255c, a layer 113S over the conductive layer 111S, the common layer 114 over the layer 113S, and the common electrode 115 over the common layer 114. The conductive layer 111S may be formed using the same material as or a different material from the above-described conductive layer 111 (the conductive layer 111R, the conductive layer 111G, and the conductive layer 111B). The layer 113S includes at least an active layer. A sidewall insulating layer 107S_1 is provided in contact with the side surfaces of the conductive layer 111S and the layer 113S. A sidewall insulating layer 107S_2 is provided in contact with the side surface of the sidewall insulating layer 107S_1 that is opposite to the side surface thereof in contact with the conductive layer 111S and the layer 113S.

Here, the layer 113S includes at least an active layer, preferably includes a plurality of functional layers. Examples of the functional layers include carrier-transport layers (a hole-transport layer and an electron-transport layer) and carrier-blocking layers (a hole-blocking layer and an electron-blocking layer). In addition, one or more layers are preferably provided over the active layer. A layer between the active layer and the mask layer can inhibit the active layer from being exposed on the outermost surface during the fabrication process of the display device and can reduce damage to the active layer. Accordingly, the reliability of the light-receiving device 150 can be improved. Thus, the layer 113S preferably includes an active layer and a carrier-blocking layer (a hole-blocking layer or an electron-blocking layer) or a carrier-transport layer (an electron-transport layer or a hole-transport layer) over the active layer.

The layer 113S is a layer that is provided in the light-receiving device 150 and is not provided in the light-emitting devices (the light-emitting device 130R, the light-emitting device 130G, and the light-emitting device 130B). Note that the functional layer other than the active layer included in the layer 113S may include the same material as the functional layer other than the light-emitting layer included in each of the layer 113R, the layer 113G, and the layer 113B. Meanwhile, the common layer 114 is a continuous layer shared by the light-emitting device and the light-receiving device.

Here, a layer shared by the light-receiving device and the light-emitting device may have different functions in the light-emitting device and the light-receiving device. In this specification, the name of a component is based on its function in the light-emitting device in some cases. For example, a hole-injection layer functions as a hole-injection layer in the light-emitting device and functions as a hole-transport layer in the light-receiving device. Similarly, an electron-injection layer functions as an electron-injection layer in the light-emitting device and functions as an electron-transport layer in the light-receiving device. A layer shared by the light-receiving device and the light-emitting device may have the same function in both the light-emitting device and the light-receiving device. The hole-transport layer functions as a hole-transport layer in both the light-emitting device and the light-receiving device, and the electron-transport layer functions as an electron-transport layer in both the light-emitting device and the light-receiving device.

The mask layer 118R is positioned between the layer 113R and the insulating layer 125, and a mask layer 118S is positioned between the layer 113S and the insulating layer 125. The mask layer 118R is a remaining part of a mask film provided over the layer 113R at the time of processing the layer 113R. The mask layer 118S is a remaining part of a mask film provided in contact with the top surface of the layer 113S at the time of processing the layer 113S, which is a layer including the active layer. The mask layer 118R and the mask layer 118S may contain the same material or different materials.

Although FIG. 13A illustrates an example in which an aperture ratio (also referred to as a size or the size of the light-emitting region or the light-receiving region) of the subpixel 11S is higher than those of the subpixel 11R, the subpixel 11G, and the subpixel 11B, one embodiment of the present invention is not limited thereto. The aperture ratio of each of the subpixel 11R, the subpixel 11G, the subpixel 11B, and the subpixel 11S can be determined as appropriate. The subpixel 11R, the subpixel 11G, the subpixel 11B, and the subpixel 11S may have different aperture ratios, or two or more of them may have the same or substantially the same aperture ratio.

The subpixel 11S may have a higher aperture ratio than at least one of the subpixel 11R, the subpixel 11G, and the subpixel 11B. The wide light-receiving area of the subpixel 11S can make it easy to detect an object in some cases. For example, in some cases, the aperture ratio of the subpixel 11S is higher than the aperture ratio of each of the other subpixels depending on the resolution of the display device and the circuit structure or the like of the subpixel.

The subpixel 11S may have a lower aperture ratio than at least one of the subpixel 11R, the subpixel 11G, and the subpixel 11B. A small light-receiving area of the subpixel 11S leads to a narrow image-capturing range, inhibits a blur in a capturing result, and improves the definition. This is preferable because high-resolution or high-definition image capturing can be performed.

As described above, the subpixel 11S can have a detection wavelength, a resolution, and an aperture ratio that are suitable for the intended use.

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

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

Embodiment 2

In this embodiment, a method for fabricating a display device of one embodiment of the present invention will be described with reference to FIG. 14A to FIG. 27B. Note that as for a material and a formation method of each component, portions similar to the portions described in Embodiment 1 are not described in some cases. The structure of the light-emitting device will be described in detail in Embodiment 5.

FIG. 14A to FIG. 24B, FIG. 25A and FIG. 25B, and FIG. 26A to FIG. 27B each illustrate a cross-sectional view along the dashed-dotted line X1-X2 and a cross-sectional view along the dashed-dotted line Y1-Y2 in FIG. 1A side by side. FIG. 25C to FIG. 25F illustrate enlarged views of the end portion of the insulating layer 127 and the vicinity thereof.

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

Thin films included in the display device (e.g., insulating films, semiconductor films, and conductive films) can also be formed by a wet film formation method such as spin coating, dipping, spray coating, ink-jetting, dispensing, screen printing, offset printing, a doctor knife method, slit coating, roll coating, curtain coating, or knife coating.

Specifically, for fabrication of the light-emitting device, a vacuum process such as an evaporation method and a solution process such as a spin coating method or an inkjet method can be used. Examples of an evaporation method include physical vapor deposition methods (PVD methods) such as a sputtering method, an ion plating method, an ion beam evaporation method, a molecular beam evaporation method, and a vacuum evaporation method, and a chemical vapor deposition method (CVD method). Specifically, functional layers (e.g., a hole-injection layer, a hole-transport layer, a hole-blocking layer, a light-emitting layer, an electron-blocking layer, an electron-transport layer, an electron-injection layer, and a charge-generation layer) included in the EL layer can be formed by a method such as an evaporation method (e.g., a vacuum evaporation method), a coating method (e.g., a dip coating method, a die coating method, a bar coating method, a spin coating method, or a spray coating method), or a printing method (e.g., an inkjet method, a screen printing (stencil) method, an offset printing (planography) method, a flexography (relief printing) method, a gravure printing method, or a micro-contact printing method).

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

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

As light used for light exposure in a photolithography method, it is possible to use light with the i-line (wavelength: 365 nm), light with the g-line (wavelength: 436 nm), light with the h-line (wavelength: 405 nm), or combined light of any of them. Ultraviolet rays, KrF laser light, ArF laser light, or the like can also be used. Light exposure may be performed by liquid immersion light exposure technique. As the light used for light exposure, extreme ultraviolet (EUV) light or X-rays may also be used. Instead of the light used for light exposure, an electron beam can be used. It is preferable to use extreme ultraviolet light, X-rays, or an electron beam because extremely minute processing can be performed. Note that a photomask is not needed when light exposure is performed by scanning with a beam such as an electron beam.

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

A fabrication method example of the display device illustrated in FIG. 1B will be described below with reference to FIG. 14A to FIG. 23C and FIG. 25A to FIG. 27B.

First, the insulating layer 255a, the insulating layer 255b, and the insulating layer 255c are formed in this order over the layer 101. Next, a conductive film 111b to be the conductive layer 111B later and the conductive layer 123 are formed over the insulating layer 255c (FIG. 14A). For example, with the use of an area mask, the conductive film 111b and the conductive layer 123 can be formed in desired regions (a region corresponding to a display portion of the display device and a region corresponding to the connection portion 140, respectively). The conductive film 111b and the conductive layer 123 can be formed by a sputtering method or a vacuum evaporation method, for example.

Examples of materials that can be used for the conductive film 111b and the conductive layer 123 include the materials that can be used for the conductive layer 111 described in Embodiment 1.

Then, a conductive film having a property of transmitting visible light may be formed over the conductive film 111b and the conductive layer 123. In the case of a top-emission display device, the conductive film 111b can be used as a reflective electrode of the display device later, as described in Embodiment 1. By contrast, the conductive film having a property of transmitting visible light can be used as a transparent electrode of the display device later. The conductive film can be formed using any of the materials that can be used for the common electrode 115 described in Embodiment 1. The conductive film can be formed by a sputtering method or a vacuum evaporation method, for example. The formation of the conductive film preferably follows the formation of the conductive film 111b and the conductive layer 123 in vacuum consistently. Note that the conductive film is not necessarily formed.

Note that in this specification and the like, a process in vacuum consistently refers to performing different steps successively in a vacuum atmosphere in an apparatus. For example, in the case where the formation of the conductive film 111b and the conductive layer 123 is followed by the formation of the conductive film having a property of transmitting visible light over the conductive film 111b and the conductive layer 123 consistently in vacuum as described above, the conductive film 111b and the conductive layer 123 are formed first in a vacuum atmosphere in an apparatus. After that, the conductive film having a property of transmitting visible light is formed successively without taking the layer 101 where the conductive film 111b, the conductive layer 123, and the like are formed out of the apparatus.

Then, the surface of the conductive film 111b is preferably subjected to hydrophobic treatment. The hydrophobic treatment can change the property of the surface of a processing target from hydrophilic to hydrophobic, or can improve the hydrophobic property of the surface of the processing target. The hydrophobic treatment for the surface of the conductive film 111b can improve the adhesion between the conductive film 111b and a film to be formed in a later step (here, a film 113b), thereby inhibiting film separation. Note that the hydrophobic treatment is not necessarily performed.

The hydrophobic treatment can be performed by fluorine modification of the conductive film 111b, for example. The fluorine modification can be performed by treatment or heat treatment using a gas containing fluorine, plasma treatment in a gas atmosphere containing fluorine, or the like. A fluorine gas can be used as the gas containing fluorine, and for example, a fluorocarbon gas can be used. As the fluorocarbon gas, a low carbon fluoride gas such as a carbon tetrafluoride (CF₄) gas, a C₄F₆ gas, a C₂F₆ gas, a C₄F₆ gas, or C₅F₈ can be used, for example. As the gas containing fluorine, a SF₆ gas, a NF₃ gas, a CHF₃ gas, or the like can also be used, for example. Moreover, a helium gas, an argon gas, a hydrogen gas, or the like can be added to any of the above gases as appropriate.

Treatment using a silylating agent is performed on the surface of the conductive film 111b after plasma treatment is performed in a gas atmosphere containing a Group 18 element such as argon, so that the surface of the conductive film 111b can have a hydrophobic property. As the silylating agent, hexamethyldisilazane (HMDS), trimethylsilylimidazole (TMSI), or the like can be used. Alternatively, treatment using a silane coupling agent is performed on the surface of the conductive film 111b after plasma treatment is performed in a gas atmosphere containing a Group 18 element such as argon, so that the surface of the conductive film 111b can have a hydrophobic property.

Plasma treatment on the surface of the conductive film 111b in a gas atmosphere containing a Group 18 element such as argon can apply damage to the surface of the conductive film 111b. Accordingly, a methyl group included in the silylating agent such as HMDS is likely to bond to the surface of the conductive film 111b. In addition, silane coupling by the silane coupling agent is likely to occur. As described above, treatment using a silylating agent or a silane coupling agent performed on the surface of the conductive film 111b after plasma treatment in a gas atmosphere containing a Group 18 element such as argon enables the surface of the conductive film 111b to have a hydrophobic property.

The treatment using a silylating agent, a silane coupling agent, or the like can be performed by application of the silylating agent, the silane coupling agent, or the like by a spin coating method, a dipping method, or the like. The treatment using a silylating agent, a silane coupling agent, or the like can also be performed by forming a film containing the silylating agent, a film containing the silane coupling agent, or the like over the conductive film 111b or the like by a gas phase method, for example. In a gas phase method, first, a material containing a silylating agent, a material containing a silane coupling agent, or the like is evaporated so that the silylating agent, the silane coupling agent, or the like is contained in an atmosphere. Next, a substrate where the conductive film 111b and the like are formed is put in the atmosphere. Accordingly, a film containing the silylating agent, the silane coupling agent, or the like can be formed over the conductive film 111b, so that the surface of the conductive film 111b can have a hydrophobic property.

Then, the film 113b to be the layer 113B later is formed over the conductive film 111b (FIG. 14B). The film 113b (to be the layer 113B later) contains a light-emitting material emitting blue light. That is, in this embodiment, an island-shaped EL layer included in the light-emitting device emitting blue light is formed first, and then island-shaped EL layers included in the light-emitting devices emitting light of the other colors are formed. Note that the present invention is not limited thereto; an island-shaped EL layer included in a light-emitting device emitting red light may be formed first. An island-shaped EL layer included in a light-emitting device emitting green light may be formed first.

As illustrated in FIG. 14B, the film 113b is not formed over the conductive layer 123 in the cross-sectional view along the dashed-dotted line Y1-Y2. For example, by using an area mask, the film 113b can be formed only in a desired region. A light-emitting device can be fabricated through a relatively simple process, by employing a film formation step using an area mask and a processing step using a resist mask.

As described in Embodiment 1, a material with high heat resistance is used for the light-emitting device of the display device of one embodiment of the present invention. Specifically, the upper temperature limit of a compound contained in the film 113b is preferably higher than or equal to 100° C. and lower than or equal to 180° C., further preferably higher than or equal to 120° C. and lower than or equal to 180° C., still further preferably higher than or equal to 140° C. and lower than or equal to 180° C. Thus, the reliability of the light-emitting device can be improved. In addition, the upper limit of the temperature that can be applied in the fabrication process of the display device can be increased. Therefore, the range of choices of the materials and the formation method of the display device can be widened, thereby improving the manufacturing yield and the reliability.

The film 113b can be formed by an evaporation method, specifically a vacuum evaporation method, for example. The film 113b may be formed by a method such as a transfer method, a printing method, an inkjet method, or a coating method. The formation of the film 113b preferably follows the formation of the conductive film 111b and the conductive layer 123 in vacuum consistently.

Next, a mask film 118b to be the mask layer 118B later and a mask film 119b to be a mask layer 119B later are formed in this order over the film 113b and the conductive layer 123 (FIG. 14B).

Although this embodiment describes an example in which the mask film is formed with a two-layer structure of the mask film 118b and the mask film 119b, the mask film may have a single-layer structure or a stacked-layer structure of three or more layers.

Providing the mask layer over the film 113b can reduce damage to the film 113b in the fabrication process of the display device, resulting in an improvement in reliability of the light-emitting device.

As the mask film 118b, a film highly resistant to the processing conditions of the film 113b, specifically, a film having high etching selectivity to the film 113b is used. As the mask film 119b, a film having high etching selectivity to the mask film 118b is used.

The mask film 118b and the mask film 119b are formed at a temperature lower than the upper temperature limit of the film 113b. The typical substrate temperatures in formation of the mask film 118b and the mask film 119b are lower than or equal to 200° C., preferably lower than or equal to 150° C., further preferably lower than or equal to 120° C., still further preferably lower than or equal to 100° C., yet still further preferably lower than or equal to 80° C.

Examples of indicators of the upper temperature limit include the glass transition point, the softening point, the melting point, the thermal decomposition temperature, and the 5% weight loss temperature. The upper temperature limits of the film 113b, a film 113g described later, and a film 113r described later (i.e., the layer 113B, the layer 113G, and the layer 113R) can each be any of the above temperatures that are indicators of the upper temperature limit, preferably the lowest one among the temperatures.

As described above, a material with high heat resistance is used for the light-emitting device of the display device of one embodiment of the present invention. Thus, the substrate temperature in formation of the mask film can be higher than or equal to 100° C., higher than or equal to 120° C., or higher than or equal to 140° C. For example, an inorganic insulating film formed at a higher temperature can be a film that is denser and has a higher barrier property. Therefore, forming the mask film at such a temperature can further reduce damage to the film 113b and improve the reliability of the light-emitting device.

As each of the mask film 118b and the mask film 119b, a film that can be removed by a wet etching method is preferably used. The use of a wet etching method can reduce damage to the film 113b in processing of the mask film 118b and the mask film 119b as compared with the case of using a dry etching method.

The mask film 118b and the mask film 119b can be formed by a sputtering method, an ALD method (including a thermal ALD method and a PEALD method), a CVD method, or a vacuum evaporation method, for example. The aforementioned wet film formation method may also be used for the formation.

The mask film 118b, which is formed over and in contact with the film 113b, is preferably formed by a formation method that causes less damage to the film 113b than a formation method of the mask film 119b. For example, the mask film 118b is preferably formed by an ALD method or a vacuum evaporation method rather than a sputtering method.

As each of the mask film 118b and the mask film 119b, it is possible to use one or more of a metal film, an alloy film, a metal oxide film, a semiconductor film, an organic insulating film, and an inorganic insulating film, for example.

For each of the mask film 118b and the mask film 119b, it is possible to use a metal material such as gold, silver, platinum, magnesium, nickel, tungsten, chromium, molybdenum, iron, cobalt, copper, palladium, titanium, aluminum, yttrium, zirconium, or tantalum or an alloy material containing any of the metal materials, for example. It is particularly preferable to use a low-melting-point material such as aluminum or silver. A metal material capable of blocking ultraviolet rays is preferably used for one or both of the mask film 118b and the mask film 119b, in which case the film 113b can be inhibited from being irradiated with ultraviolet rays and degradation of the film 113b can be inhibited.

A metal film or an alloy film is preferably used as one or both of the mask film 118b and the mask film 119b, in which case the film 113b can be inhibited from being damaged by plasma and degradation of the film 113b can be inhibited. Specifically, the film 113b can be inhibited from being damaged by plasma in a step using a dry etching method, a step performing ashing, or the like. It is particularly preferable to use a metal film such as a tungsten film or an alloy film as the mask film 119b.

For each of the mask film 118b and the mask film 119b, it is possible to use a metal oxide such as In—Ga—Zn oxide, indium oxide, In—Zn oxide, In—Sn oxide, indium titanium oxide (In—Ti oxide), indium tin zinc oxide (In—Sn—Zn oxide), indium titanium zinc oxide (In—Ti—Zn oxide), indium gallium tin zinc oxide (In—Ga—Sn—Zn oxide), or indium tin oxide containing silicon.

In place of gallium described above, an element M (M is one or more kinds selected from aluminum, silicon, boron, yttrium, copper, vanadium, beryllium, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, and magnesium) may be used. Specifically, M is preferably one or more kinds selected from gallium, aluminum, and yttrium.

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

For example, a semiconductor material such as silicon or germanium can be used as a material with a high affinity for the semiconductor manufacturing process. Alternatively, an oxide or a nitride of the semiconductor material can be used. Alternatively, a non-metallic material such as carbon or a compound thereof can be used. Alternatively, a metal, such as titanium, tantalum, tungsten, chromium, or aluminum, or an alloy containing one or more of them can be used. Alternatively, an oxide containing the above-described metal, such as titanium oxide or chromium oxide, or a nitride such as titanium nitride, chromium nitride, or tantalum nitride can be used.

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

Note that the film containing a material having a property of blocking ultraviolet rays can have the same effect even when used as a material of an insulating film 125A (an insulating film to be the insulating layer 125 later).

As each of the mask film 118b and the mask film 119b, any of a variety of inorganic insulating films that can be used as the protective layer 131 can be used. In particular, an oxide insulating film is preferable because its adhesion to the film 113b is higher than that of a nitride insulating film. For example, an inorganic insulating material such as aluminum oxide, hafnium oxide, or silicon oxide can be used for each of the mask film 118b and the mask film 119b. As each of the mask film 118b and the mask film 119b, an aluminum oxide film can be formed by an ALD method, for example. The use of an ALD method is preferable because damage to a base (in particular, the EL layer) can be reduced.

For example, an inorganic insulating film (e.g., an aluminum oxide film) formed by an ALD method can be used as the mask film 118b, and an inorganic film (e.g., an In—Ga—Zn oxide film, a silicon film, or a tungsten film) formed by a sputtering method can be used as the mask film 119b.

Note that the same inorganic insulating film can be used for all of the mask film 118b, a sidewall insulating film 107b formed later (an insulating film to be the sidewall insulating layer 107B_1 later), and the insulating film 125A formed later (the insulating film to be the insulating layer 125 later). For example, an aluminum oxide film formed by an ALD method can be used for all of the mask film 118b, the sidewall insulating film 107b, and the insulating film 125A. Here, for the mask film 118b, the sidewall insulating film 107b, and the insulating film 125A, the same film formation conditions or different film formation conditions may be employed. For example, when the mask film 118b is formed under conditions similar to those for the sidewall insulating film 107b and the insulating film 125A, the mask film 118b can be an insulating film having a high barrier property against at least one of water and oxygen. Meanwhile, the mask film 118b is a film most or all of which is to be removed in a later step, and thus is preferably easily processed. Hence, the mask film 118b is preferably formed at a substrate temperature lower than that in formation of the sidewall insulating film 107b and the insulating film 125A.

An organic material may be used for one or both of the mask film 118b and the mask film 119b. For example, as the organic material, a material that can be dissolved in a solvent chemically stable with respect to at least the uppermost film of the film 113b may be used. Specifically, a material that is dissolved in water or alcohol can be suitably used. In forming a film of such a material, it is preferable to apply the material dissolved in a solvent such as water or alcohol by a wet film formation method and then perform heat treatment for evaporating the solvent. At this time, the heat treatment is preferably performed under a reduced-pressure atmosphere, in which case the solvent can be removed at a low temperature in a short time and thermal damage to the film 113b can be accordingly reduced.

For each of the mask film 118b and the mask film 119b, an organic resin such as polyvinyl alcohol (PVA), polyvinyl butyral, polyvinylpyrrolidone, polyethylene glycol, polyglycerin, pullulan, water-soluble cellulose, an alcohol-soluble polyamide resin, or a fluororesin such as perfluoropolymer may be used.

For example, an organic film (e.g., a PVA film) formed by an evaporation method or the above wet film formation method can be used as the mask film 118b, and an inorganic film (e.g., a silicon nitride film) formed by a sputtering method can be used as the mask film 119b.

Note that as described in Embodiment 1, part of the mask film sometimes remains as a mask layer in the display device of one embodiment of the present invention.

Next, a resist mask 190B is formed over the mask film 119b (FIG. 14B). The resist mask 190B can be formed by application of a photosensitive resin (photoresist), light exposure, and development.

The resist mask 190B may be formed using either a positive resist material or a negative resist material.

The resist mask 190B is provided at a position overlapping with the position where the conductive layer 111B is formed over the mask film 119b. The resist mask 190B is preferably provided also at a position overlapping with the conductive layer 123. This can inhibit the conductive layer 123 from being damaged during the fabrication process of the display device. Note that the resist mask 190B is not necessarily provided over the conductive layer 123.

As illustrated in the cross-sectional view along Y1-Y2 in FIG. 14B, the resist mask 190B is preferably provided to cover a region from an end portion of the film 113b to an end portion of the conductive layer 123. In that case, end portions of the mask layer 118B and the mask layer 119B overlap with the end portion of the film 113b even after the mask film 118b and the mask film 119b are processed. Since the mask layer 118B and the mask layer 119B are provided to cover the region from the end portion of the film 113b to the end portion of the conductive layer 123, the insulating layer 255c can be inhibited from being exposed even after the film 113b is processed (see the cross-sectional view along Y1-Y2 in FIG. 15C). This can prevent the insulating layer 255a to the insulating layer 255c and part of the insulating layer included in the layer 101 from being eliminated by etching or the like, and the conductive layer included in the layer 101 from being exposed. Thus, unintentional electrical connection between the conductive layer and another conductive layer can be inhibited. For example, a short circuit between the conductive layer and the common electrode 115 can be inhibited.

Next, part of the mask film 119b is removed with the use of the resist mask 190B, so that the mask layer 119B is formed (FIG. 14C). The mask layer 119B remains over a region to be the conductive layer 111B later and the conductive layer 123. After that, the resist mask 190B is removed (FIG. 15A). Next, part of the mask film 118b is removed using the mask layer 119B as a mask (also referred to as a hard mask), so that the mask layer 118B is formed (FIG. 15B).

The mask film 118b and the mask film 119b can be processed by a wet etching method or a dry etching method. The mask film 118b and the mask film 119b are preferably processed by anisotropic etching

The use of a wet etching method for processing of the mask film 118b and the mask film 119b can reduce damage to the film 113b in processing of the mask film 118b and the mask film 119b as compared with the case of using a dry etching method. In the case of using a wet etching method, it is preferable to use a developer, an aqueous solution of tetramethylammonium hydroxide (TMAH), dilute hydrofluoric acid, oxalic acid, phosphoric acid, acetic acid, nitric acid, or a mixed solution containing two or more of these acids, for example. In the case of using a wet etching method, a mixed acid chemical solution containing water, phosphoric acid, diluted hydrofluoric acid, and nitric acid may be used. A chemical solution used for the wet etching treatment may be alkaline or acid.

Since the film 113b is not exposed in processing of the mask film 119b, the range of choices of the processing method is wider than that for processing of the mask film 118b. Specifically, even when a gas containing oxygen is used as an etching gas for processing the mask film 119b, the film 113b is not exposed to the gas and degradation of the film 113b can be further inhibited.

In the case of using a dry etching method for processing the mask film 118b, degradation of the film 113b can be inhibited by not using a gas containing oxygen as the etching gas. In the case of using a dry etching method, it is preferable to use a gas containing CF₄, C₄F₈, SF₆, CHF₃, Cl₂, H₂O, or BCl₃ or a noble gas (also referred to as a rare gas) such as He as the etching gas, for example.

For example, when an aluminum oxide film formed by an ALD method is used as the mask film 118b, the mask film 118b can be processed by a dry etching method using CHF₃ and He or CHF₃, He, and CH₄. In the case where an In—Ga—Zn oxide film formed by a sputtering method is used as the mask film 119b, the mask film 119b can be processed by a wet etching method using a diluted phosphoric acid. Alternatively, the mask film 119b may be processed by a dry etching method using CH₄ and Ar. In the case where a tungsten film formed by a sputtering method is used as the mask film 119b, the mask film 119b can be processed by a dry etching method using SF₆, CF₄, and O₂ or CF₄, Cl₂, and O₂.

The resist mask 190B can be removed by ashing using oxygen plasma, for example. Alternatively, an oxygen gas and any of CF₄, C₄F₈, SF₆, CHF₃, Cl₂, H₂O, BCl₃, and a noble gas (also referred to as a rare gas) such as He may be used. Alternatively, the resist mask 190B may be removed by wet etching. At this time, the mask film 118b is positioned on the outermost surface and the film 113b is not exposed; thus, the film 113b can be inhibited from being damaged in the step of removing the resist mask 190B. In addition, the range of choices of the method for removing the resist mask 190B can be widened.

Next, the film 113b is processed to form the layer 113B. For example, part of the film 113b is removed using the mask layer 119B and the mask layer 118B as a hard mask, so that the layer 113B is formed (FIG. 15C).

Accordingly, as illustrated in FIG. 15C, the stacked-layer structure of the layer 113B, the mask layer 118B, and the mask layer 119B remains over the conductive film 111b.

The film 113b is preferably processed by anisotropic etching. In particular, an anisotropic dry etching method is preferably employed. Alternatively, a wet etching method may be employed.

FIG. 15C illustrates an example in which the film 113b is processed by a dry etching method. In a dry etching apparatus, an etching gas is brought into a plasma state. Thus, the surface of the display device under fabrication is exposed to plasma (plasma 121a). Here, a metal film or an alloy film is preferably used for one or both of the mask layer 118B and the mask layer 119B, in which case a remaining portion of the film 113b (a portion to be the layer 113B) can be inhibited from being damaged by the plasma and degradation of the layer 113B can be inhibited. In particular, a metal film such as a tungsten film or an alloy film is preferably used for the mask layer 119B.

In the case of using a dry etching method, degradation of the film 113b can be inhibited by not using a gas containing oxygen as the etching gas.

A gas containing oxygen may be used as the etching gas. When the etching gas contains oxygen, the etching rate can be increased. Therefore, the etching can be performed under a low-power condition while an adequately high etching rate is maintained. Thus, damage to the film 113b can be reduced. Furthermore, a defect such as attachment of a reaction product generated at the etching can be inhibited.

In the case of using a dry etching method, it is preferable to use, as the etching gas, a gas containing one or more kinds of H₂, CF₄, C₄F₈, SF₆, CHF₃, Cl₂, H₂O, BCl₃, and a noble gas (also referred to as a rare gas) such as He and Ar, for example. Alternatively, a gas containing oxygen and at least one kind of the above is preferably used as the etching gas. Alternatively, an oxygen gas may be used as the etching gas. Specifically, for example, a gas containing H₂ and Ar or a gas containing CF₄ and He can be used as the etching gas. For another example, a gas containing CF₄, He, and oxygen can be used as the etching gas. For another example, a gas containing H₂ and Ar and a gas containing oxygen can be used as the etching gas.

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

Although not illustrated in FIG. 15C, the thickness of a region of the conductive film 111b that does not overlap with the layer 113B is sometimes reduced by the etching treatment.

In a region corresponding to the connection portion 140, a stacked-layer structure of the mask layer 118B and the mask layer 119B remains over the conductive layer 123 (FIG. 15C).

As described above, in the cross-sectional view along Y1-Y2 in FIG. 15C, the mask layer 118B and the mask layer 119B are provided to cover the end portions of the layer 113B and the end portions of the conductive layer 123, and the top surface of the insulating layer 255c is not exposed. This can prevent the insulating layer 255a to the insulating layer 255c and part of the insulating layer included in the layer 101 from being removed by etching or the like, and the conductive layer included in the layer 101 from being exposed. Thus, unintentional electrical connection between the conductive layer and another conductive layer can be inhibited.

As described above, in the method for fabricating the display device of one embodiment of the present invention, the resist mask 190B is formed over the mask film 119b and part of the mask film 119b is removed using the resist mask 190B, so that the mask layer 119B is formed. After that, part of the film 113b is removed using the mask layer 119B as a hard mask, so that the layer 113B is formed. Thus, it can be said that the layer 113B is formed by processing the film 113b by a photolithography method. Note that part of the film 113b may be removed using the resist mask 190B. Then, the resist mask 190B may be removed.

Next, the exposed portion of the conductive film 111b is removed, so that the conductive layer 111B is formed in a region overlapping with the layer 113B, the mask layer 118B, and the mask layer 119B (FIG. 16A). The exposed portion of the conductive film 111b can be removed by a wet etching method or a dry etching method. By this removal, the side surfaces of the conductive layer 111B, the layer 113B, the mask layer 118B, and the mask layer 119B are substantially aligned with each other. In addition, by this removal, the surface of the insulating layer 255c is exposed.

As described above, in the method for fabricating the display device of one embodiment of the present invention, the conductive film 111b and the film 113b are successively formed and then the film 113b and the conductive film 111b are successively processed to form the layer 113B and the conductive layer 111B, instead of forming the film 113b to be the EL layer and processing the film 113b to form the layer 113B after the formation of the conductive layer 111B to be the pixel electrode of the light-emitting device 130B is completed. Thus, a good state of the interface between the pixel electrode and the EL layer can be maintained as compared with the case where the pixel electrode and the EL layer are separately formed.

Next, the sidewall insulating film 107b to be the sidewall insulating layer 107B_1 later is formed over the insulating layer 255c and the mask layer 119B (FIG. 16B). As described above, as the sidewall insulating film 107b, the inorganic insulating film that can be used as the mask film 118b can be used. Thus, the sidewall insulating film 107b can be formed by the same formation method as the mask film 118b. Note that the sidewall insulating film 107b is not necessarily formed. In order to describe an example of the method for fabricating the display device including the sidewall insulating layers illustrated in FIG. 1B, a step of forming the sidewall insulating film 107b and the subsequent steps will be described below.

The sidewall insulating film 107b, which is formed in contact with the side surface of the layer 113B, is preferably formed by a method that causes less damage to the layer 113B. For example, an aluminum oxide film is preferably formed as the sidewall insulating film 107b by an ALD method. As illustrated in FIG. 16A, the side surfaces of the conductive layer 111B, the layer 113B, the mask layer 118B, and the mask layer 119B after the processing are substantially aligned with each other, and their side surfaces are perpendicular or substantially perpendicular to the substrate surface. When the sidewall insulating film 107b is formed by an ALD method, the sidewall insulating film 107b can be formed on the side surfaces with good coverage while damage to the layer 113B is being inhibited.

Next, the sidewall insulating layer 107B_1 is formed by processing the sidewall insulating film 107b (FIG. 16C). By processing of the sidewall insulating film 107b, the top surface of the mask layer 119B and part of the top surface of the insulating layer 255c are exposed in a region indicated by the dashed-dotted line X1-X2. By the processing, the sidewall insulating layer 107B_1 is formed in contact with the side surfaces of the conductive layer 111B, the layer 113B, the mask layer 118B, and the mask layer 119B. Meanwhile, a substantially flat portion of the top surface of the mask layer 119B is exposed in a region indicated by the dashed-dotted line Y1-Y2. A remaining material layer 107C_1 is in contact with a portion of the mask layer 119B that has a side surface inclined to the substrate surface.

The sidewall insulating layer 107B_1 can be formed by performing etching substantially uniformly on the top surface of the sidewall insulating film 107b, for example. Such uniform etching for planarization is also referred to as etch-back processing. Note that the sidewall insulating layer 107B_1 can also be formed by a photolithography method.

The sidewall insulating film 107b can be processed by a wet etching method or a dry etching method, and is preferably processed by a dry etching method. The sidewall insulating film 107b is preferably processed by anisotropic etching.

The shape of the end portion of the sidewall insulating layer 107B_1 can be a rounded shape. For example, the end portion of the sidewall insulating layer 107B_1 has a rounded shape as illustrated in FIG. 16C, FIG. 1B, and the like when an upper portion of the sidewall insulating film 107b is etched by anisotropic etching in formation of the sidewall insulating layer 107B_1 by a dry etching method. The end portion of the sidewall insulating layer 107B_1 preferably has a rounded shape, in which case coverage with a film to be formed later can be improved.

As illustrated in FIG. 16A, the side surface of the conductive layer 111B is exposed after the processing. This might induce a defect such as corrosion of the conductive layer 111B due to an etchant that is used for processing a film above the conductive layer 111B by a wet etching method later and is in direct contact with the conductive layer 111B, for example.

In the method for fabricating the display device of one embodiment of the present invention, the sidewall insulating layer 107B_1 covering the side surface of the conductive layer 111B is provided after the processing of the conductive layer 111B. This protects the side surface of the conductive layer 111B, thereby inhibiting generation of the above-described defect. In addition, the common electrode provided over the EL layer later is inhibited from being in contact with the pixel electrode (the conductive layer 111B), which can prevent a short circuit in the light-emitting device.

Providing the sidewall insulating layer 107B_1 also protects the end portion of the layer 113B. This can inhibit generation of a defect in a later step, such as damage to the end portion of the layer 113B or degradation of the characteristics of the light-emitting device due to entry of impurities or the like through the end portion of the layer 113B.

Next, a conductive film 111g to be the conductive layer 111G later is formed over the insulating layer 255c, the sidewall insulating layer 107B_1, and the mask layer 119B overlapping with the conductive layer 111B (FIG. 17A). For example, with the use of an area mask, the conductive film 111g can be formed in a desired region (a region corresponding to the display portion of the display device). The conductive film 111g can be formed by the same method as the conductive film 111b. The conductive film 111g can be formed using the same material as the conductive film 111b.

Here, as illustrated in FIG. 15C, when the film 113b is processed by a dry etching method to form the layer 113B, the surface of the conductive film 111b is exposed to plasma (the plasma 121a) generated at the time of the etching. Thus, the surface of the conductive film 111b in a region not covered with the layer 113B, the mask layer 118B, or the mask layer 119B at the time of the etching might be damaged by the plasma. When such a region of the conductive film 111b is processed in a later step and used as the pixel electrodes (the conductive layer 111G and the conductive layer 111R) of the light-emitting devices, the states of the interfaces between the EL layer and each of the conductive layer 111G and the conductive layer 111R are degraded, which might cause defects such as the increased driving voltage of the light-emitting device 130G and the light-emitting device 130R and the decreased reliability of the light-emitting device 130G and the light-emitting device 130R due to the increased driving voltage.

In the method for fabricating the display device of one embodiment of the present invention, a region of the conductive film 111b other than a region where the pixel electrode (the conductive layer 111B) is formed (i.e., a region that might be damaged by plasma) is removed as illustrated in FIG. 16A. Then, as illustrated in FIG. 17A, a conductive film (the conductive film 111g) for forming a pixel electrode (the conductive layer 111G) different from the conductive layer 111B is separately formed. Thus, the conductive film (the conductive film 111g) that is not damaged by plasma or the like in the previous step and has high quality can be used for forming the pixel electrode (the conductive layer 111G) different from the conductive layer 111B.

Then, a conductive film having a property of transmitting visible light may be formed over the conductive film 111g. In the case of a top-emission display device, the conductive film 111g can be used as a reflective electrode of the display device later, as described in Embodiment 1. By contrast, the conductive film having a property of transmitting visible light can be used as a transparent electrode of the display device later. The conductive film can be formed using any of the materials that can be used for the common electrode 115 described in Embodiment 1. The conductive film can be formed by a sputtering method or a vacuum evaporation method, for example. The formation of the conductive film preferably follows the formation of the conductive film 111g in vacuum consistently. Note that the conductive film is not necessarily formed.

Then, the surface of the conductive film 111g is preferably subjected to hydrophobic treatment. The hydrophobic treatment for the surface of the conductive film 111g can improve the adhesion between the conductive film 111g and a film to be formed in a later step (here, the film 113g), thereby inhibiting film separation. The hydrophobic treatment can be performed by the same method as that performed on the surface of the conductive film 111b described above. Note that the hydrophobic treatment is not necessarily performed.

Then, the film 113g to be the layer 113G later is formed over the conductive film 111g (FIG. 17B). The film 113g (to be the layer 113G later) contains a light-emitting material emitting green light. That is, this embodiment shows an example in which an island-shaped EL layer included in the light-emitting device emitting green light is formed second. Note that the present invention is not limited thereto; an island-shaped EL layer included in a light-emitting device emitting red light may be formed second. An island-shaped EL layer included in a light-emitting device emitting blue light may be formed second.

The film 113g can be formed by a method similar to a method that can be employed for forming the film 113b. The formation of the film 113g preferably follows the formation of the conductive film 111g in vacuum consistently.

Next, over the film 113g, a mask film 118g to be the mask layer 118G later and a mask film 119g to be a mask layer 119G later are formed in this order, and then a resist mask 190G is formed (FIG. 17B). The materials and the formation methods of the mask film 118g and the mask film 119g are similar to conditions applicable to the mask film 118b and the mask film 119b. The materials and the formation method of the resist mask 190G are similar to conditions applicable to the resist mask 190B.

The resist mask 190G is provided at a position overlapping with the position where the conductive layer 111G is formed over the mask film 119g.

Next, part of the mask film 119g is removed with the use of the resist mask 190G, so that the mask layer 119G is formed (FIG. 17C). The mask layer 119G remains over a region to be the conductive layer 111G later. After that, the resist mask 190G is removed (FIG. 18A). Next, part of the mask film 118g is removed using the mask layer 119G as a mask, so that the mask layer 118G is formed (FIG. 18B). Next, the film 113g is processed to form the layer 113G. For example, part of the film 113g is removed using the mask layer 119G and the mask layer 118G as a hard mask, so that the layer 113G is formed (FIG. 18C).

The film 113g is preferably processed by anisotropic etching. In particular, an anisotropic dry etching method is preferably employed. Alternatively, a wet etching method may be employed.

FIG. 18C illustrates an example in which the film 113g is processed by a dry etching method. The surface of the display device under fabrication is exposed to plasma (plasma 121b). Here, a metal film or an alloy film is preferably used for one or both of the mask layer 118G and the mask layer 119G, in which case a remaining portion of the film 113g (the layer 113G) can be inhibited from being damaged by the plasma and degradation of the layer 113G can be inhibited. In particular, a metal film such as a tungsten film or an alloy film is preferably used for the mask layer 119G.

Accordingly, as illustrated in FIG. 18C, the stacked-layer structure of the layer 113G, the mask layer 118G, and the mask layer 119G remains over the conductive film 111g. At this time, the surface of the mask layer 119B is covered with the conductive film 111g.

Next, the exposed portion of the conductive film 111g is removed, so that the conductive layer 111G is formed in a region overlapping with the layer 113G, the mask layer 118G, and the mask layer 119G (FIG. 19A). The exposed portion of the conductive film 111g can be removed by a wet etching method or a dry etching method. By this removal, the side surfaces of the conductive layer 111G, the layer 113G, the mask layer 118G, and the mask layer 119G are substantially aligned with each other. In addition, by this removal, the surface of the mask layer 119B and part of the surface of the insulating layer 255c are exposed.

As described above, in the method for fabricating the display device of one embodiment of the present invention, the conductive film 111g and the film 113g are successively formed and then the film 113g and the conductive film 111g are successively processed to form the layer 113G and the conductive layer 111G, instead of forming the film 113g to be the EL layer and processing the film 113g to form the layer 113G after the formation of the conductive layer 111G to be the pixel electrode of the light-emitting device 130G is completed. Thus, a good state of the interface between the pixel electrode and the EL layer can be maintained as compared with the case where the pixel electrode and the EL layer are separately formed.

Next, a sidewall insulating film 107g to be the sidewall insulating layer 107G_1 and the sidewall insulating layer 107B_2 later is formed over the insulating layer 255c, the mask layer 119B, the sidewall insulating layer 107B_1, and the mask layer 119G (FIG. 19B). The sidewall insulating film 107g can be formed using the same material as the sidewall insulating film 107b. Thus, the sidewall insulating film 107g can be formed by the same formation method as the sidewall insulating film 107b. Note that the sidewall insulating film 107g is not necessarily formed. In order to describe an example of the method for fabricating the display device including the sidewall insulating layers illustrated in FIG. 1B, a step of forming the sidewall insulating film 107g and the subsequent steps will be described below.

The sidewall insulating film 107g, which is formed in contact with the side surface of the layer 113G, is preferably formed by a method that causes less damage to the layer 113G. For example, an aluminum oxide film is preferably formed as the sidewall insulating film 107g by an ALD method. As illustrated in FIG. 19A, the side surfaces of the conductive layer 111G, the layer 113G, the mask layer 118G, and the mask layer 119G after the processing are substantially aligned with each other, and their side surfaces are perpendicular or substantially perpendicular to the substrate surface. When the sidewall insulating film 107g is formed by an ALD method, the sidewall insulating film 107g can be formed on the side surfaces with good coverage while damage to the layer 113G is being inhibited.

Next, the sidewall insulating layer 107G_1 and the sidewall insulating layer 107B_2 are formed by processing the sidewall insulating film 107g (FIG. 19C). By processing of the sidewall insulating film 107g, the top surface of the mask layer 119B, the top surface of the mask layer 119G, and part of the top surface of the insulating layer 255c are exposed in the region indicated by the dashed-dotted line X1-X2. By the processing, the sidewall insulating layer 107G_1 is formed in contact with the side surfaces of the conductive layer 111G, the layer 113G, the mask layer 118G, and the mask layer 119G. In addition, the sidewall insulating layer 107B_2 is formed in contact with the side surface of the sidewall insulating layer 107B_1 (the surface opposite to the surface thereof in contact with the conductive layer 111B, the layer 113B, the mask layer 118B, and the mask layer 119B). Meanwhile, the substantially flat portion of the top surface of the mask layer 119B is exposed in the region indicated by the dashed-dotted line Y1-Y2. A remaining material layer 107C_2 is in contact with the side surface of the material layer 107C_1 in the portion of the mask layer 119B that has the side surface inclined to the substrate surface.

The sidewall insulating layer 107G_1 and the sidewall insulating layer 107B_2 can be formed by the same method as the sidewall insulating layer 107B_1.

The shapes of the end portions of the sidewall insulating layer 107G_1 and the sidewall insulating layer 107B_2 can each be a rounded shape. For example, the end portions of the sidewall insulating layer 107G_1 and the sidewall insulating layer 107B_2 have a rounded shape as illustrated in FIG. 19C, FIG. 1B, and the like when an upper portion of the sidewall insulating film 107g is etched by anisotropic etching in formation of the sidewall insulating layer 107G_1 and the sidewall insulating layer 107B_2 by a dry etching method. The end portions of the sidewall insulating layer 107G_1 and the sidewall insulating layer 107B_2 preferably have a rounded shape, in which case coverage with a film to be formed later can be improved.

As illustrated in FIG. 19A, the side surface of the conductive layer 111G is exposed after the processing. This might induce a defect such as corrosion of the conductive layer 111G due to an etchant that is used for processing a film above the conductive layer 111G by a wet etching method later and is in direct contact with the conductive layer 111G, for example.

In the method for fabricating the display device of one embodiment of the present invention, the sidewall insulating layer 107G_1 covering the side surface of the conductive layer 111G is provided after the processing of the conductive layer 111G. This protects the side surface of the conductive layer 111G, thereby inhibiting generation of the above-described defect. In addition, the common electrode provided over the EL layer later is inhibited from being in contact with the pixel electrode (the conductive layer 111G), which can prevent a short circuit in the light-emitting device.

Providing the sidewall insulating layer 107G_1 also protects the end portion of the layer 113G. This can inhibit generation of a defect in a later step, such as damage to the end portion of the layer 113G or degradation of the characteristics of the light-emitting device due to entry of impurities or the like through the end portion of the layer 113G.

Next, a conductive film 111r to be the conductive layer 111R later is formed over the insulating layer 255c, the sidewall insulating layer 107B_1, the sidewall insulating layer 107B_2, the sidewall insulating layer 107G_1, the mask layer 119G, and the mask layer 119B overlapping with the conductive layer 111B (FIG. 20A). For example, with the use of an area mask, the conductive film 111r can be formed in a desired region (a region corresponding to the display portion of the display device). The conductive film 111r can be formed by the same method as the conductive film 111b and the conductive film 111g. The conductive film 111r can be formed using the same material as the conductive film 111b and the conductive film 111g.

Here, as illustrated in FIG. 18C, when the film 113g is processed by a dry etching method to form the layer 113G, the surface of the conductive film 111g is exposed to plasma (the plasma 121b) generated at the time of the etching. Thus, the surface of the conductive film 111g in a region not covered with the layer 113G, the mask layer 118G, or the mask layer 119G at the time of the etching might be damaged by the plasma. When such a region of the conductive film 111g is processed in a later step and used as the pixel electrode (the conductive layer 111R) of the light-emitting device, the state of the interface between the EL layer and the conductive layer 111R is degraded, which might cause defects such as the increased driving voltage of the light-emitting device 130R and the decreased reliability of the light-emitting device 130R due to the increased driving voltage.

In the method for fabricating the display device of one embodiment of the present invention, a region of the conductive film 111g other than a region where the pixel electrode (the conductive layer 111G) is formed (i.e., a region that might be damaged by plasma) is removed as illustrated in FIG. 19A. Then, as illustrated in FIG. 20A, a conductive film (the conductive film 111r) for forming a pixel electrode (the conductive layer 111R) different from the conductive layer 111G is separately formed. Thus, the conductive film (the conductive film 111r) that is not damaged by plasma or the like in the previous step and has high quality can be used for forming the pixel electrode (the conductive layer 111R) different from the conductive layer 111G.

Then, a conductive film having a property of transmitting visible light may be formed over the conductive film 111r. In the case of a top-emission display device, the conductive film 111r can be used as a reflective electrode of the display device later, as described in Embodiment 1. By contrast, the conductive film having a property of transmitting visible light can be used as a transparent electrode of the display device later. The conductive film can be formed using any of the materials that can be used for the common electrode 115 described in Embodiment 1. The conductive film can be formed by a sputtering method or a vacuum evaporation method, for example. The formation of the conductive film preferably follows the formation of the conductive film 111r in vacuum consistently. Note that the conductive film is not necessarily formed.

Then, the surface of the conductive film 111r is preferably subjected to hydrophobic treatment. The hydrophobic treatment for the surface of the conductive film 111r can improve the adhesion between the conductive film 111r and a film to be formed in a later step (here, the film 113r), thereby inhibiting film separation. The hydrophobic treatment can be performed by the same method as that performed on the surface of the conductive film 111b and the surface of the conductive film 111g described above. Note that the hydrophobic treatment is not necessarily performed.

Then, the film 113r to be the layer 113R later is formed over the conductive film 111r (FIG. 20B). The film 113r (to be the layer 113R later) contains a light-emitting material emitting red light. That is, this embodiment shows an example in which an island-shaped EL layer included in the light-emitting device emitting red light is formed third. Note that the present invention is not limited thereto; an island-shaped EL layer included in a light-emitting device emitting green light may be formed third. An island-shaped EL layer included in a light-emitting device emitting blue light may be formed third.

The film 113r can be formed by a method similar to a method that can be employed for forming the film 113b and the film 113g. The formation of the film 113r preferably follows the formation of the conductive film 111r in vacuum consistently.

Next, over the film 113r, a mask film 118r to be the mask layer 118R later and a mask film 119r to be a mask layer 119R later are formed in this order, and then a resist mask 190R is formed (FIG. 20B). The materials and the formation methods of the mask film 118r and the mask film 119r are similar to conditions applicable to the mask film 118b, the mask film 119b, the mask film 118g, and the mask film 119g. The materials and the formation method of the resist mask 190R are similar to conditions applicable to the resist mask 190B and the resist mask 190G.

The resist mask 190R is provided at a position overlapping with the position where the conductive layer 111R is formed over the mask film 119r.

Next, part of the mask film 119r is removed with the use of the resist mask 190R, so that the mask layer 119R is formed (FIG. 20C). The mask layer 119R remains over a region to be the conductive layer 111R later. After that, the resist mask 190R is removed (FIG. 21A). Next, part of the mask film 118r is removed using the mask layer 119R as a mask, so that the mask layer 118R is formed (FIG. 21B). Next, the film 113r is processed to form the layer 113R. For example, part of the film 113r is removed using the mask layer 119R and the mask layer 118R as a hard mask, so that the layer 113R is formed (FIG. 21C).

The film 113r is preferably processed by anisotropic etching. In particular, an anisotropic dry etching method is preferably employed. Alternatively, a wet etching method may be employed.

FIG. 21C illustrates an example in which the film 113r is processed by a dry etching method. The surface of the display device under fabrication is exposed to plasma (plasma 121c). Here, a metal film or an alloy film is preferably used for one or both of the mask layer 118R and the mask layer 119R, in which case a remaining portion of the film 113r (the layer 113R) can be inhibited from being damaged by the plasma and degradation of the layer 113R can be inhibited. In particular, a metal film such as a tungsten film or an alloy film is preferably used for the mask layer 119R.

Accordingly, as illustrated in FIG. 21C, the stacked-layer structure of the layer 113R, the mask layer 118R, and the mask layer 119R remains over the conductive film 111r. At this time, the surfaces of the mask layer 119B and the mask layer 119G are covered with the conductive film 111r.

As described above, the distance between adjacent two layers among the layer 113B, the layer 113G, and the layer 113R formed by a photolithography method can be shortened to less than or equal to 8 μm, less than or equal to 5 μm, less than or equal to 3 μm, less than or equal to 2 μm, or less than or equal to 1 μm. Here, the distance can be determined by, for example, the distance between facing end portions of adjacent two layers among the layer 113B, the layer 113G, and the layer 113R. When the distance between the island-shaped EL layers is shortened in this manner, a display device with a high resolution and a high aperture ratio can be provided.

Next, the exposed portion of the conductive film 111r is removed, so that the conductive layer 111R is formed in a region overlapping with the layer 113R, the mask layer 118R, and the mask layer 119R (FIG. 22A). The exposed portion of the conductive film 111r can be removed by a wet etching method or a dry etching method. By this removal, the side surfaces of the conductive layer 111R, the layer 113R, the mask layer 118R, and the mask layer 119R are substantially aligned with each other. In addition, by this removal, the surfaces of the mask layer 119B and the mask layer 119G and part of the surface of the insulating layer 255c are exposed.

As described above, in the method for fabricating the display device of one embodiment of the present invention, the conductive film 111r and the film 113r are successively formed and then the film 113r and the conductive film 111r are successively processed to form the layer 113R and the conductive layer 111R, instead of forming the film 113r to be the EL layer and processing the film 113r to form the layer 113R after the formation of the conductive layer 111R to be the pixel electrode of the light-emitting device 130R is completed. Thus, a good state of the interface between the pixel electrode and the EL layer can be maintained as compared with the case where the pixel electrode and the EL layer are separately formed.

Next, a sidewall insulating film 107r to be the sidewall insulating layer 107R_1, the sidewall insulating layer 107G_2, and the sidewall insulating layer 107B_3 later is formed over the insulating layer 255c, the mask layer 119B, the sidewall insulating layer 107B_1, the sidewall insulating layer 107B_2, the mask layer 119G, the sidewall insulating layer 107G_1, and the mask layer 119R (FIG. 22B). The sidewall insulating film 107r can be formed using the same material as the sidewall insulating film 107b and the sidewall insulating film 107g. Thus, the sidewall insulating film 107r can be formed by the same formation method as the sidewall insulating film 107b and the sidewall insulating film 107g. Note that the sidewall insulating film 107r is not necessarily formed. In order to describe an example of the method for fabricating the display device including the sidewall insulating layers illustrated in FIG. 1B, a step of forming the sidewall insulating film 107r and the subsequent steps will be described below.

The sidewall insulating film 107r, which is formed in contact with the side surface of the layer 113R, is preferably formed by a method that causes less damage to the layer 113R. For example, an aluminum oxide film is preferably formed as the sidewall insulating film 107r by an ALD method. As illustrated in FIG. 22A, the side surfaces of the conductive layer 111R, the layer 113R, the mask layer 118R, and the mask layer 119R after the processing are substantially aligned with each other, and their side surfaces are perpendicular or substantially perpendicular to the substrate surface. When the sidewall insulating film 107r is formed by an ALD method, the sidewall insulating film 107r can be formed on the side surfaces with good coverage while damage to the layer 113R is being inhibited.

Next, the sidewall insulating layer 107R_1, the sidewall insulating layer 107G_2, and the sidewall insulating layer 107B_3 are formed by processing the sidewall insulating film 107r (FIG. 22C). By processing of the sidewall insulating film 107r, the top surface of the mask layer 119B, the top surface of the mask layer 119G, the top surface of the mask layer 119R, and part of the top surface of the insulating layer 255c are exposed in the region indicated by the dashed-dotted line X1-X2. By the processing, the sidewall insulating layer 107R_1 is formed in contact with the side surfaces of the conductive layer 111R, the layer 113R, the mask layer 118R, and the mask layer 119R. In addition, the sidewall insulating layer 107G_2 is formed in contact with the side surface of the sidewall insulating layer 107G_1 (the surface opposite to the surface thereof in contact with the conductive layer 111G, the layer 113G, the mask layer 118G, and the mask layer 119G). Moreover, the sidewall insulating layer 107B_3 is formed in contact with the side surface of the sidewall insulating layer 107B_2 (the surface opposite to the surface thereof in contact with the sidewall insulating layer 107B_1). Meanwhile, the substantially flat portion of the top surface of the mask layer 119B is exposed in the region indicated by the dashed-dotted line Y1-Y2. A remaining material layer 107C_3 is in contact with the side surface of the material layer 107C_2 in the portion of the mask layer 119B that has the side surface inclined to the substrate surface.

The sidewall insulating layer 107R_1, the sidewall insulating layer 107G_2, and the sidewall insulating layer 107B_3 can be formed by the same method as the sidewall insulating layer 107B_1, the sidewall insulating layer 107G_1, and the sidewall insulating layer 107B_2.

The shapes of the end portions of the sidewall insulating layer 107R_1, the sidewall insulating layer 107G_2, and the sidewall insulating layer 107B_3 can each be a rounded shape. For example, the end portions of the sidewall insulating layer 107R_1, the sidewall insulating layer 107G_2, and the sidewall insulating layer 107B_3 have a rounded shape as illustrated in FIG. 22C, FIG. 1B, and the like when an upper portion of the sidewall insulating film 107r is etched by anisotropic etching in formation of the sidewall insulating layer 107R_1, the sidewall insulating layer 107G_2, and the sidewall insulating layer 107B_3 by a dry etching method. The end portions of the sidewall insulating layer 107R_1, the sidewall insulating layer 107G_2, and the sidewall insulating layer 107B_3 preferably have a rounded shape, in which case coverage with a film to be formed later can be improved.

As illustrated in FIG. 22A, the side surface of the conductive layer 111R is exposed after the processing. This might induce a defect such as corrosion of the conductive layer 111R due to an etchant that is used for processing a film above the conductive layer 111R by a wet etching method later and is in direct contact with the conductive layer 111R, for example.

In the method for fabricating the display device of one embodiment of the present invention, the sidewall insulating layer 107R_1 covering the side surface of the conductive layer 111R is provided after the processing of the conductive layer 111R. This protects the side surface of the conductive layer 111R, thereby inhibiting generation of the above-described defect. In addition, the common electrode provided over the EL layer later is inhibited from being in contact with the pixel electrode (the conductive layer 111R), which can prevent a short circuit in the light-emitting device.

Providing the sidewall insulating layer 107R_1 also protects the end portion of the layer 113R. This can inhibit generation of a defect in a later step, such as damage to the end portion of the layer 113R or degradation of the characteristics of the light-emitting device due to entry of impurities or the like through the end portion of the layer 113R.

Next, the mask layer 119B, the mask layer 119G, and the mask layer 119R are preferably removed (FIG. 23A). The mask layer 118B, the mask layer 118G, the mask layer 118R, the mask layer 119B, the mask layer 119G, and the mask layer 119R remain in the display device in some cases, depending on the later steps. Removing the mask layer 119B, the mask layer 119G, and the mask layer 119R at this stage can inhibit the mask layer 119B, the mask layer 119G, and the mask layer 119R from remaining in the display device. For example, in the case where a conductive material is used for each of the mask layer 119B, the mask layer 119G, and the mask layer 119R, removing the mask layer 119B, the mask layer 119G, and the mask layer 119R in advance can inhibit generation of leakage current due to the remaining mask layer 119B, mask layer 119G, and mask layer 119R, formation of a capacitor, and the like.

Although this embodiment describes an example in which the mask layer 119B, the mask layer 119G, and the mask layer 119R are removed, the mask layer 119B, the mask layer 119G, and the mask layer 119R are not necessarily removed. For example, in the case where the mask layer 119B, the mask layer 119G, and the mask layer 119R each include the aforementioned material having a property of blocking ultraviolet rays, the process preferably proceeds to the next step without removing the mask layers, in which case the island-shaped EL layers can be protected from ultraviolet rays.

The step of removing the mask layer 119B, the mask layer 119G, and the mask layer 119R can be performed by a method similar to that for the step of processing the mask layer 119B, the mask layer 119G, and the mask layer 119R. In particular, the use of a wet etching method can reduce damage to the layer 113B, the layer 113G, and the layer 113R at the time of removing the mask layer 119B, the mask layer 119G, and the mask layer 119R compared with the case of using a dry etching method.

In the case where a metal film or an alloy film is used for each of the mask layer 119B, the mask layer 119G, and the mask layer 119R, the mask layer 119B, the mask layer 119G, and the mask layer 119R can inhibit plasma damage to the EL layers. Thus, film processing can be performed by a dry etching method in the steps before the removal of the mask layer 119B, the mask layer 119G, and the mask layer 119R. By contrast, in the step of removing the mask layer 119B, the mask layer 119G, and the mask layer 119R and in the steps after the removal, the film inhibiting plasma damage to the EL layers does not exist; thus, film processing is preferably performed by a method that does not use plasma, such as a wet etching method.

The mask layer 119B, the mask layer 119G, and the mask layer 119R may be removed by being dissolved in a solvent such as water or alcohol. Examples of alcohol include ethyl alcohol, methyl alcohol, isopropyl alcohol (IPA), and glycerin.

After the mask layer 119B, the mask layer 119G, and the mask layer 119R are removed, drying treatment may be performed to remove water contained in the layer 113B, the layer 113G, and the layer 113R and water adsorbed onto the surfaces of the layer 113B, the layer 113G, and the layer 113R. For example, heat treatment in an inert gas atmosphere such as a nitrogen atmosphere or a reduced-pressure atmosphere can be performed. The heat treatment can be performed at a substrate temperature higher than or equal to 50° C. and lower than or equal to 200° C., preferably higher than or equal to 60° C. and lower than or equal to 150° C., further preferably higher than or equal to 70° C. and lower than or equal to 120° C. A reduced-pressure atmosphere is preferable because drying at a lower temperature is possible.

Next, the insulating film 125A to be the insulating layer 125 later is formed to cover the conductive layer 111B, the conductive layer 111G, the conductive layer 111R, the layer 113B, the layer 113G, the layer 113R, the mask layer 118B, the mask layer 118G, the mask layer 118R, the sidewall insulating layer 107B_1, the sidewall insulating layer 107B_2, the sidewall insulating layer 107B_3, the sidewall insulating layer 107G_1, the sidewall insulating layer 107G_2, and the sidewall insulating layer 107R_1 (FIG. 23A).

As illustrated in FIG. 8C, the display device of one embodiment of the present invention can have a structure without the sidewall insulating layers. In the case of fabricating such a display device, the sidewall insulating film 107b, the sidewall insulating film 107g, and the sidewall insulating film 107r do not need to be formed. Thus, in the case of fabricating the display device illustrated in FIG. 8C, a cross-sectional shape before removal of the mask layer 119B, the mask layer 119G, and the mask layer 119R (corresponding to the cross-sectional view in FIG. 22C in the case of fabricating the display device illustrated in FIG. 1B) becomes a shape illustrated in FIG. 24A. A cross-sectional shape after the removal of the mask layer 119B, the mask layer 119G, and the mask layer 119R and the formation of the insulating film 125A (corresponding to the cross-sectional view in FIG. 23A in the case of fabricating the display device illustrated in FIG. 1B) becomes a shape illustrated in FIG. 24B.

An example of the method for fabricating the display device illustrated in FIG. 1B including the sidewall insulating layers will be described below, and the following description can also be applied to the case of fabricating the display device illustrated in FIG. 8C not including the sidewall insulating layers.

After the mask layer 119B, the mask layer 119G, and the mask layer 119R are removed (FIG. 23A), an insulating film 127a is formed in contact with the top surface of the insulating film 125A as described later. Thus, the top surface of the insulating film 125A preferably has high adhesion to a resin composite (e.g., a photosensitive resin composite containing an acrylic resin) that is used for the insulating film 127a. To improve the adhesion, the top surface of the insulating film 125A is preferably made hydrophobic (or more hydrophobic) by surface treatment. For example, the treatment is preferably performed using a silylating agent such as hexamethyldisilazane (HMDS). By hydrophobizing the top surface of the insulating film 125A in this manner, the insulating film 127a can be formed with high adhesion. Note that the above-described hydrophobization treatment may be performed as the surface treatment.

Then, the insulating film 127a is formed over the insulating film 125A (FIG. 23B).

The insulating film 125A and the insulating film 127a are preferably formed by a formation method that causes less damage to the layer 113B, the layer 113G, and the layer 113R.

The insulating film 125A and the insulating film 127a are formed at a temperature lower than the upper temperature limits of the layer 113B, the layer 113G, and the layer 113R. When the insulating film 125A is formed at a high substrate temperature, the formed film, even with a small thickness, can have a low impurity concentration and a high barrier property against at least one of water and oxygen.

The insulating film 125A and the insulating film 127a are preferably formed at a substrate temperature higher than or equal to 60° C., higher than or equal to 80° C., higher than or equal to 100° C., or higher than or equal to 120° C. and lower than or equal to 200° C., lower than or equal to 180° C., lower than or equal to 160° C., lower than or equal to 150° C., or lower than or equal to 140° C.

As described above, a material with high heat resistance is used for the light-emitting device of the display device of one embodiment of the present invention. Thus, the substrate temperature in formation of the insulating film 125A and the insulating film 127a can be higher than or equal to 100° C., higher than or equal to 120° C., or higher than or equal to 140° C. For example, an inorganic insulating film formed at a higher temperature can be a film that is denser and has a higher barrier property. Therefore, forming the insulating film 125A at such a temperature can further reduce damage to the layer 113B, the layer 113G, and the layer 113R in a later step and improve the reliability of the light-emitting device.

As the insulating film 125A, an insulating film is preferably formed within the above substrate temperature range to have a thickness greater than or equal to 3 nm, greater than or equal to 5 nm, or greater than or equal to 10 nm and less than or equal to 200 nm, less than or equal to 150 nm, less than or equal to 100 nm, or less than or equal to 50 nm.

The insulating film 125A is preferably formed by an ALD method, for example. The use of an ALD method is preferable because damage due to film formation can be reduced and a film with good coverage can be formed. As the insulating film 125A, an aluminum oxide film is preferably formed by an ALD method, for example.

Alternatively, the insulating film 125A may be formed by a sputtering method, a CVD method, or a PECVD method that provides a higher film formation speed than an ALD method. In that case, a highly reliable display device can be fabricated with high productivity.

The insulating film 127a is preferably formed by the aforementioned wet film formation method. For example, the insulating film 127a is preferably formed by spin coating using a photosensitive resin, specifically, a photosensitive resin composite containing an acrylic resin.

Heat treatment (also referred to as pre-baking) is preferably performed after formation of the insulating film 127a. The heat treatment is performed at a temperature lower than the upper temperature limits of the layer 113B, the layer 113G, and the layer 113R. The substrate temperature in the heat treatment is preferably higher than or equal to 50° C. and lower than or equal to 200° C., further preferably higher than or equal to 60° C. and lower than or equal to 150° C., still further preferably higher than or equal to 70° C. and lower than or equal to 120° C. Accordingly, a solvent contained in the insulating film 127a can be removed.

Next, the insulating film 127a is partly exposed to light by irradiating part of the insulating film 127a with light 139 (e.g., visible light or ultraviolet rays) (FIG. 23C). In the case where a positive photosensitive resin composite containing an acrylic resin is used for the insulating film 127a, a region where the insulating layer 127 is not formed in a later step is irradiated with the light 139 using a mask 136. The insulating layer 127 is formed in regions interposed between two of the conductive layer 111R, the conductive layer 111G, and the conductive layer 111B, and around the conductive layer 123. Thus, as illustrated in FIG. 23C, in the insulating film 127a, a portion overlapping with the conductive layer 111R, a portion overlapping with the conductive layer 111G, a portion overlapping the conductive layer 111B, and a portion overlapping with the conductive layer 123 are irradiated with the light 139.

Note that the width of the insulating layer 127 to be formed later can be controlled by the region exposed to the light here. In this embodiment, the insulating layer 127 is processed so as to include portions overlapping with the top surfaces of the conductive layer 111R, the conductive layer 111G, and the conductive layer 111B (FIG. 2A). As illustrated in FIG. 5A or FIG. 5B, the insulating layer 127 does not necessarily include the portions overlapping with the top surfaces of the conductive layer 111R, the conductive layer 111G, and the conductive layer 111B.

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

Although FIG. 23C illustrates an example in which a positive photosensitive resin is used for the insulating film 127a and a region where the insulating layer 127 is not formed is irradiated with visible light or ultraviolet rays, the present invention is not limited thereto. For example, a structure may be employed in which a negative photosensitive resin is used for the insulating film 127a. In that case, a region where the insulating layer 127 is formed is irradiated with the light 139 with a different mask.

Next, as illustrated in FIG. 25A, the region of the insulating film 127a exposed to light is removed by development, so that an insulating layer 127b is formed. The insulating layer 127b is formed in regions interposed between two of the conductive layer 111R, the conductive layer 111G, and the conductive layer 111B, and a region surrounding the conductive layer 123. Here, in the case where an acrylic resin is used for the insulating film 127a, an alkaline solution is preferably used as a developer, and for example, an aqueous solution of tetramethyl ammonium hydroxide (TMAH) can be used.

Note that a step of removing a development residue (what is called a scum) may be performed after development. For example, the residue can be removed by ashing using oxygen plasma. The step of removing a residue may be performed after each development step described below.

Etching treatment may be performed to adjust the surface level of the insulating layer 127b. The insulating layer 127b may be processed by ashing using oxygen plasma, for example.

Note that after development and before post-baking (described later), light exposure may be performed on the entire substrate, by which the insulating layer 127b is irradiated with visible light or ultraviolet rays. The energy density for the light exposure is preferably greater than 0 mJ/cm² and less than or equal to 800 mJ/cm², further preferably greater than 0 mJ/cm² and less than or equal to 500 mJ/cm². Performing such light exposure after development can improve the transparency of the insulating layer 127b in some cases. In addition, the insulating layer 127b can be changed into a tapered shape at low temperatures in some cases.

By contrast, when light exposure is not performed on the insulating layer 127b, the shape of the insulating layer 127b can be easily changed or the insulating layer 127b can be easily changed into a tapered shape in a later step in some cases. Thus, it is sometimes preferable not to perform light exposure on the insulating layer 127b after development.

After that, heat treatment (also referred to as post-baking) is performed. As illustrated in FIG. 25B, by performing the heat treatment, the insulating layer 127b can be transformed into the insulating layer 127 having a tapered side surface. The heat treatment is performed at a temperature lower than the upper temperature limit of the EL layers. The heat treatment can be performed at a substrate temperature higher than or equal to 50° C. and lower than or equal to 200° C., preferably higher than or equal to 60° C. and lower than or equal to 150° C., further preferably higher than or equal to 70° C. and lower than or equal to 130° C. The heating atmosphere may be either an air atmosphere or an inert gas atmosphere. Alternatively, the heating atmosphere may be either an atmospheric pressure atmosphere or a reduced-pressure atmosphere. A reduced-pressure atmosphere is preferable because drying at a lower temperature is possible. The heat treatment in this step is preferably performed at a higher substrate temperature than the heat treatment (pre-baking) after formation of the insulating film 127a. In that case, the adhesion between the insulating layer 127 and the insulating layer 125 and the corrosion resistance of the insulating layer 127 can be improved.

As illustrated in FIG. 4A and FIG. 4B, the side surface of the insulating layer 127 might have a concave shape depending on the materials for the insulating layer 127, or the temperature, time, and atmosphere of the post-baking. For example, the insulating layer 127 is more likely to be changed in shape to have a concave shape as the temperature is higher or the time is longer in the post-baking conditions. In addition, as described above, in the case where light exposure is not performed on the insulating layer 127b after development, the shape of the insulating layer 127 is sometimes easily changed at the time of the post-baking.

Next, as illustrated in FIG. 25B, etching treatment is performed using the insulating layer 127 as a mask to remove parts of the insulating film 125A, the mask layer 118B, the mask layer 118G, and the mask layer 118R. Consequently, openings are formed in the insulating film 125A, the mask layer 118B, the mask layer 118G, and the mask layer 118R, and parts of the top surfaces of the layer 113B, the layer 113G, the layer 113R, and the conductive layer 123 are exposed. In addition, the insulating layer 125 is formed by removing part of the insulating film 125A.

The etching treatment can be performed by a dry etching method or a wet etching method. Note that the insulating film 125A is preferably formed using a material similar to that for the mask layer 118B, the mask layer 118G, and the mask layer 118R, in which case the etching treatment can be performed collectively.

In the case where a dry etching method is employed, a chlorine-based gas is preferably used. As the chlorine-based gas, Cl₂, BCl₃, SiCl₄, CCl₄, and the like can be used alone or two or more of the gases can be mixed and used. Furthermore, one or more of an oxygen gas, a hydrogen gas, a helium gas, an argon gas, and the like can be mixed and added to the chlorine-based gas as appropriate. By employing a dry etching method, the thin regions of the mask layer 118B, the mask layer 118G, and the mask layer 118R can be formed with good in-plane uniformity.

In the case where a dry etching method is employed, a by-product or the like generated by the dry etching treatment is sometimes deposited on the top surface and the side surface of the insulating layer 127, for example. Thus, a component contained in the etching gas, a component contained in the insulating film 125A, components contained in the mask layer 118B, the mask layer 118G, and the mask layer 118R, or the like might be contained in the insulating layer 127 in the completed display device.

The etching treatment is preferably performed by a wet etching method. Using a wet etching method can reduce damage to the layer 113B, the layer 113G, and the layer 113R, as compared to the case of using a dry etching method. For example, wet etching treatment can be performed using an alkaline solution or the like. For example, for wet etching treatment of an aluminum oxide film, it is preferable to use an aqueous solution of tetramethyl ammonium hydroxide (TMAH) that is an alkaline solution. In that case, the wet etching treatment can be performed by a puddle method.

In the manner described above, providing the insulating layer 127, the insulating layer 125, the mask layer 118B, the mask layer 118G, and the mask layer 118R can inhibit the common layer 114 and the common electrode 115 between the light-emitting devices from having connection defects due to a disconnected portion and an increased electric resistance due to a locally thinned portion. Thus, the display quality of the display device of one embodiment of the present invention can be improved.

After parts of the layer 113B, the layer 113G, and the layer 113R are exposed, additional heat treatment may be performed. The heat treatment can remove water contained in the EL layer, water adsorbed onto the surface of the EL layer, and the like. In addition, the heat treatment changes the shape of the insulating layer 127 in some cases. Specifically, the insulating layer 127 may be extended to cover at least one of the end portion of the insulating layer 125, the end portions of the mask layer 118B, the mask layer 118G, and the mask layer 118R, and the top surfaces of the layer 113B, the layer 113G, and the layer 113R. For example, the insulating layer 127 may have a shape illustrated in FIG. 3A and FIG. 3B. For example, heat treatment in an inert gas atmosphere or a reduced-pressure atmosphere can be performed. The heat treatment can be performed at a substrate temperature higher than or equal to 50° C. and lower than or equal to 200° C., preferably higher than or equal to 60° C. and lower than or equal to 150° C., further preferably higher than or equal to 70° C. and lower than or equal to 120° C. A reduced-pressure atmosphere is preferable because dehydration at a lower temperature is possible. Note that the temperature range of the heat treatment is preferably determined as appropriate in consideration of the upper temperature limit of the EL layer. In consideration of the upper temperature limit of the EL layer, temperatures higher than or equal to 70° C. and lower than or equal to 120° C. are particularly preferable in the above temperature range.

Here, when the insulating layer 125 and the mask layer are collectively etched after the post-baking, the insulating layer 125 and the mask layer below the end portion of the insulating layer 127 are eliminated by side etching and accordingly a cavity is formed in some cases. The cavity causes unevenness in the formation surface of the common layer 114 and the common electrode 115, so that step disconnection is likely to occur in the common layer 114 and the common electrode 115. To avoid this, etching treatment for the insulating layer 125 and etching treatment for the mask layer are preferably performed separately before and after the post-baking.

A method for performing etching treatment for the insulating layer 125 and etching treatment for the mask layers (the mask layer 118B, the mask layer 118G, and the mask layer 118R) separately before and after the post-baking will be described below with reference to FIG. 25C to FIG. 25F.

FIG. 25C is an enlarged view of the layer 113G, the end portion of the insulating layer 127b, and the vicinity thereof illustrated in FIG. 25A. In other words, FIG. 25C illustrates the insulating layer 127b formed by development.

Next, as illustrated in FIG. 25D, etching treatment is performed using the insulating layer 127b as a mask to remove part of the insulating film 125A, so that the mask layer 118B (not illustrated), the mask layer 118G, and the mask layer 118R (not illustrated) are partly thinned. Accordingly, the insulating layer 125 is formed below the insulating layer 127b. In addition, the surfaces of the thinned portions of the mask layer 118B, the mask layer 118G, and the mask layer 118R are exposed. Note that the etching treatment using the insulating layer 127b as a mask is referred to as first etching treatment below in some cases.

The first etching treatment can be performed by a dry etching method or a wet etching method.

As illustrated in FIG. 25D, when etching treatment is performed using the insulating layer 127b having a tapered side surface as a mask, the side surface of the insulating layer 125 and the upper end portions of the side surfaces of the mask layer 118B, the mask layer 118G, and the mask layer 118R can relatively easily have tapered shapes.

As illustrated in FIG. 25D, in the first etching treatment, the etching treatment is stopped when the mask layer 118B, the mask layer 118G, and the mask layer 118R are thinned, before the mask layers are completely removed. When the mask layer 118B, the mask layer 118G, and the mask layer 118R remain over the layer 113B, the layer 113G, and the layer 113R, respectively, the layer 113B, the layer 113G, and the layer 113R can be prevented from being damaged by treatment in a later step.

Although the mask layer 118B, the mask layer 118G, and the mask layer 118R are thinned in FIG. 25D, the present invention is not limited thereto. For example, depending on the thickness of the insulating film 125A and the thicknesses of the mask layer 118B, the mask layer 118G, and the mask layer 118R, the first etching treatment might be stopped before the insulating film 125A is processed into the insulating layer 125. Specifically, the first etching treatment might be stopped after reducing the thickness of only part of the insulating film 125A. In the case where the insulating film 125A is formed using a material similar to that for each of the mask layer 118B, the mask layer 118G, and the mask layer 118R and a boundary between the insulating film 125A and each of the mask layer 118B, the mask layer 118G, and the mask layer 118R is unclear, whether the insulating layer 125 is formed or whether the mask layer 118B, the mask layer 118G, and the mask layer 118R are thinned cannot be determined in some cases.

Although FIG. 25D illustrates an example in which the shape of the insulating layer 127b is not changed from that in FIG. 25C, the present invention is not limited thereto. For example, the end portion of the insulating layer 127b droops to cover the end portion of the insulating layer 125 in some cases. In another case, the end portion of the insulating layer 127b is in contact with the top surfaces of the mask layer 118B, the mask layer 118G, and the mask layer 118R, for example. As described above, in the case where light exposure is not performed on the insulating layer 127b after development, the shape of the insulating layer 127b is sometimes easily changed.

Next, post-baking is performed. As illustrated in FIG. 25E, by the post-baking, the insulating layer 127b can be transformed into the insulating layer 127 with a tapered side surface. As described above, in some cases, the insulating layer 127b is already changed in shape and has a tapered side surface at the time when the first etching treatment is finished.

The first etching treatment does not remove the mask layer 118B, the mask layer 118G, and the mask layer 118R completely to make the thinned mask layer 118B, mask layer 118G, and mask layer 118R remain, thereby preventing the layer 113B, the layer 113G, and the layer 113R from being damaged by the heat treatment and degrading. Thus, the reliability of the light-emitting devices can be improved.

Next, as illustrated in FIG. 25F, etching treatment is performed using the insulating layer 127 as a mask to remove parts of the mask layer 118B, the mask layer 118G, and the mask layer 118R. Consequently, openings are formed in the mask layer 118B, the mask layer 118G, and the mask layer 118R, and parts of the top surfaces of the layer 113B, the layer 113G, the layer 113R, and the conductive layer 123 are exposed. Note that the etching treatment using the insulating layer 127 as a mask is referred to as second etching treatment below in some cases.

The end portion of the insulating layer 125 is covered with the insulating layer 127. FIG. 25F illustrates an example in which part of the end portion of the mask layer 118G (specifically, the tapered portion formed by the first etching treatment) is covered with the insulating layer 127 and the tapered portion formed by the second etching treatment is exposed. That is, the structure corresponds to that illustrated in FIG. 2A and FIG. 2B.

By using a method in which etching treatment is performed before and after post-baking in this manner, even when a cavity is formed under the end portion of the insulating layer 127b by side etching of the insulating layer 125 and the mask layers (the mask layer 118B, the mask layer 118G, and the mask layer 118R) in the first etching treatment, the subsequent post-baking can make the insulating layer 127 fill the cavity. After that, since the second etching treatment etches the thinned mask layer, the amount of side etching is small and thus a cavity is not easily formed, and even if a cavity is formed, it can be extremely small. Therefore, the flatness of the formation surface of the common layer 114 and the common electrode 115 formed later can be improved.

Note that as illustrated in FIG. 3A and FIG. 3B, the insulating layer 127 may cover the entire end portion of the mask layer 118G. For example, the end portion of the insulating layer 127 droops to cover the end portion of the mask layer 118G in some cases. In another case, the end portion of the insulating layer 127 is in contact with the top surface of at least one of the layer 113B, the layer 113G, and the layer 113R, for example. As described above, in the case where light exposure is not performed on the insulating layer 127b after development, the shape of the insulating layer 127 is easily changed in some cases.

The second etching treatment is preferably performed by a wet etching method. Using a wet etching method can reduce damage to the layer 113B, the layer 113G, and the layer 113R, as compared to the case of using a dry etching method. The wet etching treatment can be performed using an alkaline solution or the like.

Note that an apparatus and a method that can be used for the etching treatment of the insulating film 125A might be limited. For example, the etching treatment of the insulating film 125A is preferably performed by a puddle method using a development apparatus and a developer because the above-described first etching treatment is performed before post-baking. This allows the insulating film 125A to be processed without providing a new apparatus in addition to the apparatuses used for light exposure, development, and post-baking. For example, in the case where an aluminum oxide film is used as the insulating film 125A, the insulating film 125A can be processed by wet etching treatment using a developer including TMAH.

Here, wet etching treatment is preferably performed by a method that consumes a small amount of etchant; for example, a puddle method is preferable. Note that the etching area of the insulating film 125A in the connection portion 140 is extremely larger than the etching area of the insulating film 125A in the display portion. Therefore, in the connection portion 140, a shortage of the etchant is caused by the puddle method, for example, and the etching rate is likely to be lower than that in the display portion. The difference in etching rate between the display portion and the connection portion 140 causes a problem of unstable processing of the insulating film 125A. For example, when the etching time is determined in accordance with the etching rate in the connection portion 140, the insulating film 125A in the display portion might be etched excessively. When the etching time is determined in accordance with the etching rate in the display portion, the insulating film 125A in the connection portion 140 might remain without being sufficiently etched. Meanwhile, in a method in which a new liquid is constantly supplied so as not to cause a difference in etching rate (e.g., a spin method), a large amount of etchant is consumed.

In view of the above, light exposure and development of the insulating film 127a in the connection portion 140 may be performed separately from light exposure and development of the insulating film 127a in the display portion. This allows the etching conditions (e.g., etching time) of the insulating film 125A in the connection portion 140 to be controlled independently from those in the display portion, thereby inhibiting both excess etching of the insulating film 125A in the display portion and insufficient etching of the insulating film 125A in the connection portion 140, so that the insulating film 125A can be processed into a desired shape.

Next, a process of the case where light exposure and development of the insulating film 127a in the display portion are performed separately from light exposure and development of the insulating film 127a in the connection portion 140 will be described with reference to FIG. 26A to FIG. 26C.

After the insulating film 127a is formed (FIG. 23B), light exposure is performed on the connection portion 140 (FIG. 26A). Specifically, the insulating film 127a is partly exposed to light by irradiating a region of the insulating film 127a that overlaps with the conductive layer 123 with the light 139 (visible light or ultraviolet rays) using a mask 136a.

Next, the region of the insulating film 127a exposed to light is removed by development. Thus, the insulating film 127a is formed in the whole display portion and a region surrounding the conductive layer 123 (FIG. 26B).

There is no particular limitation on the development method, and a dip method, a spin method, a puddle method, a vibration method, or the like can be employed. Note that in order to stabilize the etching rate, a method in which a new liquid is constantly supplied is preferably employed. Alternatively, a method in which supply and holding (development) of a liquid are repeated (also referred to as a step puddle method) is preferably employed. The step puddle method is preferable because liquid consumption can be reduced and the etching rate can be stabilized as compared to the method in which a new liquid is constantly supplied.

Next, etching treatment is performed using the insulating film 127a as a mask to remove part of the insulating film 125A in the connection portion 140 and thin part of the mask layer 118B. In the connection portion 140, a surface of the thinned portion of the mask layer 118B is exposed (FIG. 26B).

A method that can be used for the first etching treatment described above can be employed for the etching treatment.

In the etching treatment performed on the connection portion 140, the etching treatment is stopped when the mask layer 118B is thinned, before the mask layer 118B is completely removed. The mask layer 118B in the connection portion 140 is processed also in etching treatment described later. When the mask layer 118B is completely removed in the etching treatment at this stage, the insulating film 125A and the mask layer 118B below the end portion of the insulating layer 127 are eliminated by side etching in the subsequent etching treatment, which might cause a cavity. When the mask layer 118B remains over the conductive layer 123 in this manner, excess etching of the mask layer 118B and damage to the conductive layer 123 can be prevented in a later process.

Note that depending on the thickness of the insulating film 125A and the thickness of the mask layer 118B, the etching treatment might be stopped after reducing the thickness of only part of the insulating film 125A. In the case where the insulating film 125A is formed using a material similar to that for the mask layer 118B and accordingly the boundary between the insulating film 125A and the mask layer 118B is unclear, whether the insulating film 125A is removed or thinned and whether the mask layer 118B is thinned cannot be determined in some cases.

Next, light exposure is performed in the display portion (FIG. 26B). Specifically, the insulating film 127a is partly exposed to light by irradiating a region of the insulating film 127a that overlaps with the conductive layer 111R, a region of the insulating film 127a that overlaps with the conductive layer 111G, and a region of the insulating film 127a that overlaps with the conductive layer 111B with the light 139 (visible light or ultraviolet rays) using a mask 136b.

Next, the region of the insulating film 127a exposed to light is removed by development, so that the insulating layer 127b is formed (FIG. 26C). The insulating layer 127b is formed in regions interposed between two of the conductive layer 111R, the conductive layer 111G, and the conductive layer 111B, and a region surrounding the conductive layer 123.

Next, etching treatment is performed using the insulating layer 127b as a mask to remove part of the insulating film 125A, so that the mask layer 118B, the mask layer 118G, and the mask layer 118R are partly thinned. Accordingly, the insulating layer 125 is formed below the insulating layer 127b. In addition, the surfaces of the thinned portions of the mask layer 118B, the mask layer 118G, and the mask layer 118R are exposed.

Note that the process of the etching treatment described above is similar to that of the first etching treatment illustrated in FIG. 25D above. A method that can be used for the first etching treatment described above can be employed for the etching treatment.

Note that the mask layer 118B in the connection portion 140 is completely removed to expose the conductive layer 123 at the time of FIG. 26C in some cases.

After that, the above-described post-baking and second etching treatment are performed, whereby the insulating layer 125 and the insulating layer 127 can be formed.

As described above, light exposure and development of a film to be the insulating layer 127 in the connection portion 140 are performed separately from light exposure and development of the film in the display portion, whereby the processing conditions of the insulating film 125A to be the insulating layer 125 in the connection portion 140 can be controlled independently from those in the display portion. As a result, the insulating layer 125 can be processed into a desired shape to reduce defects in fabricating the display device.

Note that a difference in etching rate between the connection portion 140 and the display portion can be sufficiently small in some cases depending on the apparatus, the method, and the like of the etching treatment. Furthermore, a difference between the etching area of the insulating film 125A in the connection portion 140 and the etching area of the insulating film 125A in the display portion can be sufficiently small in some cases depending on the layout of the connection portion 140 and the insulating layer 127b, and the like. In such a case, light exposure and development of the insulating film 127a for the display portion and the connection portion 140 are preferably performed in the same process, as illustrated in FIG. 23C and FIG. 25A. This can reduce the number of steps.

Next, the common layer 114 and the common electrode 115 are formed in this order over the insulating layer 127, the layer 113B, the layer 113G, and the layer 113R (FIG. 27A), and the protective layer 131 is further formed (FIG. 27B). Then, the substrate 120 is bonded onto the protective layer 131 with the resin layer 122, whereby the display device can be fabricated (FIG. 1B).

The common layer 114 can be formed by a method such as an evaporation method (including a vacuum evaporation method), a transfer method, a printing method, an inkjet method, or a coating method.

The common electrode 115 can be formed by a sputtering method or a vacuum evaporation method, for example. Alternatively, a film formed by an evaporation method and a film formed by a sputtering method may be stacked.

Examples of methods for forming the protective layer 131 include a vacuum evaporation method, a sputtering method, a CVD method, and an ALD method.

As described above, in the method for fabricating the display device of this embodiment, the island-shaped layer 113B, the island-shaped layer 113G, and the island-shaped layer 113R are formed not by using a fine metal mask but by processing a film formed on the entire surface; thus, the island-shaped layers can be formed to have a uniform thickness. Consequently, a high-resolution display device or a display device with a high aperture ratio can be obtained. Furthermore, even when the resolution or the aperture ratio is high and the distance between subpixels is extremely short, contact between the layer 113B, the layer 113G, and the layer 113R can be inhibited in adjacent subpixels. Accordingly, generation of leakage current between subpixels can be inhibited. This can prevent crosstalk due to unintended light emission, so that a display device with extremely high contrast can be obtained.

In the method for fabricating the display device of this embodiment, the conductive films (the conductive film 111b, the conductive film 111g, and the conductive film 111r) to be the pixel electrodes of the light-emitting devices and the films (the film 113b, the film 113g, and the film 113r) including the light-emitting layers are successively formed and then successively processed to form the island-shaped pixel electrodes (the conductive layer 111B, the conductive layer 111G, and the conductive layer 111R) and the island-shaped light-emitting layers (the layer 113B, the layer 113G, and the layer 113R) in the respective light-emitting devices (the light-emitting device 130B, the light-emitting device 130G, and the light-emitting device 130R), instead of forming the island-shaped light-emitting layers after the formation of the pixel electrodes of all the light-emitting devices. This prevents the pixel electrode from being exposed in the formation of the light-emitting layer in each light-emitting device. Thus, when the light-emitting layer in one light-emitting device is formed, the pixel electrodes of the other light-emitting devices where the light-emitting layers are not formed can be prevented from being damaged by the formation process. Accordingly, a good state of the interface between the pixel electrode and the EL layer of each light-emitting device is maintained, which can inhibit generation of a defect such as an increase in the driving voltage of each light-emitting device due to the damage. Inhibiting the increase in the driving voltage of each light-emitting device can increase the lifetime and reliability of each light-emitting device. Moreover, the yield and characteristics of each light-emitting device can be improved. In addition, the light-emitting device of each color can emit light at high luminance.

After the island-shaped pixel electrodes (the conductive layer 111B, the conductive layer 111G, and the conductive layer 111R) and the island-shaped light-emitting layers (the layer 113B, the layer 113G, and the layer 113R) are formed, the sidewall insulating layers (the sidewall insulating layer 107B_1, the sidewall insulating layer 107B_2, the sidewall insulating layer 107B_3, the sidewall insulating layer 107G_1, the sidewall insulating layer 107G_2, and the sidewall insulating layer 107R_1) covering the side surfaces of the pixel electrodes and the light-emitting layers are provided. This can inhibit generation of a defect such as corrosion of the pixel electrode due to an etchant that is used for processing a film above the pixel electrode by a wet etching method and is in direct contact with the pixel electrode, for example. Providing the sidewall insulating layer also protects the end portion of the light-emitting layer, which can inhibit generation of a defect in a later step, such as damage to the end portion of the light-emitting layer or degradation of the characteristics of the light-emitting device due to entry of impurities or the like through the end portion of the light-emitting layer.

Provision of the insulating layer 127 having a tapered end portion between adjacent island-shaped EL layers can inhibit formation of step disconnection in the common layer 114 and the common electrode 115 and prevent formation of a locally thinned portion in the common layer 114 and the common electrode 115 at the time of forming the common layer 114 and the common electrode 115. This can inhibit the common layer 114 and the common electrode 115 from having connection defects due to the disconnected portion and an increased electric resistance due to the locally thinned portion. Thus, the display device of one embodiment of the present invention can have both higher resolution and higher display quality.

This embodiment can be combined with any of the other embodiments as appropriate.

Embodiment 3

In this embodiment, a display device of one embodiment of the present invention will be described with reference to FIG. 28A to FIG. 29K.

[Pixel Layout]

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

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

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

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

The pixel 110 illustrated in FIG. 28A employs S-stripe arrangement. The pixel 110 illustrated in FIG. 28A is composed of three subpixels: a subpixel 110a, a subpixel 110b, and a subpixel 110c.

The pixel 110 illustrated in FIG. 28B includes the subpixel 110a whose top surface has a rough trapezoidal shape with rounded corners, the subpixel 110b whose top surface has a rough triangle shape with rounded corners, and the subpixel 110c whose top surface has a rough tetragonal or rough hexagonal shape with rounded corners. The subpixel 110b has a larger light-emitting area than the subpixel 110a. In this manner, the shapes and sizes of the subpixels can be determined independently. For example, the size of a subpixel including a light-emitting device with higher reliability can be smaller.

Pixels 124a and pixels 124b illustrated in FIG. 28C employ PenTile arrangement. FIG. 28C illustrates an example in which the pixels 124a each including the subpixel 110a and the subpixel 110b and the pixels 124b each including the subpixel 110b and the subpixel 110c are alternately arranged.

The pixels 124a and the pixels 124b illustrated in FIG. 28D to FIG. 28F employ delta The pixels 124a each include two subpixels (the subpixel 110a and the subpixel arrangement. 110b) in the upper row (first row) and one subpixel (the subpixel 110c) in the lower row (second row). The pixels 124b each include one subpixel (the subpixel 110c) in the upper row (first row) and two subpixels (the subpixel 110a and the subpixel 110b) in the lower row (second row).

FIG. 28D illustrates an example in which each subpixel has a rough tetragonal top surface shape with rounded corners, FIG. 28E illustrates an example in which each subpixel has a circular top surface shape, and FIG. 28F illustrates an example in which each subpixel has a rough hexagonal top surface shape with rounded corners.

In FIG. 28F, the subpixels are placed inside the respective hexagonal regions that are arranged densely. Focusing on one of the subpixels, the subpixel is placed so as to be surrounded by six subpixels. The subpixels are arranged such that subpixels that emit light of the same color are not adjacent to each other. For example, focusing on the subpixel 110a, the subpixel 110a is surrounded by three subpixels 110b and three subpixels 110c that are alternately arranged.

FIG. 28G illustrates an example in which subpixels of different colors are arranged in a zigzag manner. Specifically, the positions of the top sides of two subpixels arranged in the column direction (e.g., the subpixel 110a and the subpixel 110b, or the subpixel 110b and the subpixel 110c) are not aligned in a plan view.

For example, in each pixel illustrated in FIG. 28A to FIG. 28G, it is preferable that the subpixel 110a be a subpixel R emitting red light, the subpixel 110b be a subpixel G emitting green light, and the subpixel 110c be a subpixel B emitting blue light. Note that the structure of the subpixels is not limited to this, and the colors and arrangement order of the subpixels can be determined as appropriate. For example, the subpixel 110b may be the subpixel R emitting red light and the subpixel 110a may be the subpixel G emitting green light.

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

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

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

As illustrated in FIG. 29A to FIG. 291, the pixel can include four types of subpixels.

The pixels 110 illustrated in FIG. 29A to FIG. 29C employ stripe arrangement.

FIG. 29A illustrates an example in which each subpixel has a rectangular top surface shape, FIG. 29B illustrates an example in which each subpixel has a top surface shape formed by combining two half circles and a rectangle, and FIG. 29C illustrates an example in which each subpixel has an elliptical top surface shape.

The pixels 110 illustrated in FIG. 29D to FIG. 29F employ matrix arrangement.

FIG. 29D illustrates an example in which each subpixel has a square top surface shape, FIG. 29E illustrates an example in which each subpixel has a rough square top surface shape with rounded corners, and FIG. 29F illustrates an example in which each subpixel has a circular top surface shape.

FIG. 29G and FIG. 29H each illustrate an example in which one pixel 110 is composed of two rows and three columns.

The pixel 110 illustrated in FIG. 29G includes three subpixels (the subpixel 110a, the subpixel 110b, and the subpixel 110c) in the upper row (first row) and one subpixel (a subpixel 110d) in the lower row (second row). In other words, the pixel 110 includes the subpixel 110a in the left column (first column), the subpixel 110b in the center column (second column), the subpixel 110c in the right column (third column), and the subpixel 110d across these three columns.

The pixel 110 illustrated in FIG. 29H includes three subpixels (the subpixel 110a, the subpixel 110b, and the subpixel 110c) in the upper row (first row) and three subpixels 110d in the lower row (second row). In other words, the pixel 110 includes the subpixel 110a and the subpixel 110d in the left column (first column), the subpixel 110b and the subpixel 110d in the center column (second column), and the subpixel 110c and the subpixel 110d in the right column (third column). Matching the positions of the subpixels in the upper row and the lower row as illustrated in FIG. 29H enables efficient removal of dust and the like that would be produced in the manufacturing process. Thus, a display device with high display quality can be provided.

FIG. 291 illustrates an example in which one pixel 110 is composed of three rows and two columns.

The pixel 110 illustrated in FIG. 291 includes the subpixel 110a in the upper row (first row), the subpixel 110b in the center row (second row), the subpixel 110c across the first and second rows, and one subpixel (the subpixel 110d) in the lower row (third row). In other words, the pixel 110 includes the subpixel 110a and the subpixel 110b in the left column (first column), the subpixel 110c in the right column (second column), and the subpixel 110d across these two columns.

The pixels 110 illustrated in FIG. 29A to FIG. 291 are each composed of four subpixels: the subpixel 110a, the subpixel 110b, the subpixel 110c, and the subpixel 110d.

The subpixel 110a, the subpixel 110b, the subpixel 110c, and the subpixel 110d can include light-emitting devices emitting light of different colors. The subpixel 110a, the subpixel 110b, the subpixel 110c, and the subpixel 110d are subpixels of four colors of R, G, B, and white (W), subpixels of four colors of R, G, B, and Y, or four subpixels of R, G, B, and infrared light (IR), for example.

In the pixels 110 illustrated in FIG. 29A to FIG. 291, it is preferable that the subpixel 110a be the subpixel R emitting red light, the subpixel 110b be the subpixel G emitting green light, the subpixel 110c be the subpixel B emitting blue light, and the subpixel 110d be any of a subpixel W emitting white light, a subpixel Y emitting yellow light, and a subpixel IR emitting near-infrared light, for example. In the case of such a structure, stripe arrangement is employed as the layout of R, G, and B in the pixels 110 illustrated in FIG. 29G and FIG. 29H, leading to higher display quality. In addition, what is called S-stripe arrangement is employed as the layout of R, G, and B in the pixel 110 illustrated in FIG. 291, leading to higher display quality.

The pixel 110 may include a subpixel including a light-receiving device.

In the pixels 110 illustrated in FIG. 29A to FIG. 291, any one of the subpixel 110a to the subpixel 110d may be a subpixel including a light-receiving device.

In the pixels 110 illustrated in FIG. 29A to FIG. 291, for example, it is preferable that the subpixel 110a be the subpixel R emitting red light, the subpixel 110b be the subpixel G emitting green light, the subpixel 110c be the subpixel B emitting blue light, and the subpixel 110d be a subpixel S including a light-receiving device. In the case of such a structure, stripe arrangement is employed as the layout of R, G, and B in the pixels 110 illustrated in FIG. 29G and FIG. 29H, leading to higher display quality. In addition, what is called S-stripe arrangement is employed as the layout of R, G, and B in the pixel 110 illustrated in FIG. 291, leading to higher display quality. There is no particular limitation on the wavelength of light detected by the subpixel S including a light-receiving device. The subpixel S can have a structure in which one or both of visible light and infrared light are detected.

As illustrated in FIG. 29J and FIG. 29K, the pixel can include five types of subpixels.

FIG. 29J illustrates an example in which one pixel 110 is composed of two rows and three columns.

The pixel 110 illustrated in FIG. 29J includes three subpixels (the subpixel 110a, the subpixel 110b, and the subpixel 110c) in the upper row (first row) and two subpixels (the subpixel 110d and a subpixel 110e) in the lower row (second row). In other words, the pixel 110 includes the subpixel 110a and the subpixel 110d in the left column (first column), the subpixel 110b in the center column (second column), the subpixel 110c in the right column (third column), and the subpixel 110e across the second and third columns.

FIG. 29K illustrates an example in which one pixel 110 is composed of three rows and two columns.

The pixel 110 illustrated in FIG. 29K includes the subpixel 110a in the upper row (first row), the subpixel 110b in the center row (second row), the subpixel 110c across the first and second rows, and two subpixels (the subpixel 110d and the subpixel 110e) in the lower row (third row). In other words, the pixel 110 includes the subpixel 110a, the subpixel 110b, and the subpixel 110d in the left column (first column), and the subpixel 110c and the subpixel 110e in the right column (second column).

In the pixels 110 illustrated in FIG. 29J and FIG. 29K, for example, it is preferable that the subpixel 110a be the subpixel R emitting red light, the subpixel 110b be the subpixel G emitting green light, and the subpixel 110c be the subpixel B emitting blue light. In the case of such a structure, stripe arrangement is employed as the layout of the subpixel R, the subpixel G, and the subpixel B in the pixel 110 illustrated in FIG. 29J, leading to higher display quality. In addition, what is called S-stripe arrangement is employed as the layout of the subpixel R, the subpixel G, and the subpixel B in the pixel 110 illustrated in FIG. 29K, leading to higher display quality.

In the pixels 110 illustrated in FIG. 29J and FIG. 29K, for example, it is preferable to use the subpixel S including a light-receiving device as at least one of the subpixel 110d and the subpixel 110e. In the case where light-receiving devices are used in both the subpixel 110d and the subpixel 110e, the light-receiving devices may have different structures. For example, the wavelength ranges of detected light may be different at least partly. Specifically, one of the subpixel 110d and the subpixel 110e may include a light-receiving device mainly detecting visible light and the other may include a light-receiving device mainly detecting infrared light.

In the pixels 110 illustrated in FIG. 29J and FIG. 29K, it is preferable that, for example, the subpixel S including a light-receiving device be used as one of the subpixel 110d and the subpixel 110e and a subpixel including a light-emitting device that can be used as a light source be used as the other. For example, it is preferable that one of the subpixel 110d and the subpixel 110e be the subpixel IR emitting infrared light and the other be the subpixel S including a light-receiving device detecting infrared light.

In a pixel including the subpixel R, the subpixel G, the subpixel B, the subpixel IR, and the subpixel S, while an image is displayed using the subpixel R, the subpixel G, and the subpixel B, reflected light of infrared light emitted from the subpixel IR that is used as a light source can be detected by the subpixel S.

As described above, the pixel composed of the subpixels each including the light-emitting device can employ any of a variety of layouts in the display device of one embodiment of the present invention. The display device of one embodiment of the present invention can have a structure in which the pixel includes both a light-emitting device and a light-receiving device. Also in this case, any of a variety of layouts can be employed.

This embodiment can be combined with any of the other embodiments as appropriate.

Embodiment 4

In this embodiment, display devices of one embodiment of the present invention will be described with reference to FIG. 30A to FIG. 40.

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

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

[Display Module]

FIG. 30A is a perspective view of a display module 280. The display module 280 includes a display device 100A and an FPC 290. Note that the display device included in the display module 280 is not limited to the display device 100A and may be any of a display device 100B to a display device 100F described later.

The display module 280 includes a substrate 291 and a substrate 292. The display module 280 includes a display portion 281. The display portion 281 is a region of the display module 280 where an image is displayed, and is a region where light emitted from pixels provided in a pixel portion 284 described later can be seen.

FIG. 30B is a perspective view schematically illustrating a structure on the substrate 291 side. Over the substrate 291, a circuit portion 282, a pixel circuit portion 283 over the circuit portion 282, and the pixel portion 284 over the pixel circuit portion 283 are stacked. A terminal portion 285 to be connected to the FPC 290 is provided in a portion over the substrate 291 that does not overlap with the pixel portion 284. The terminal portion 285 and the circuit portion 282 are electrically connected to each other through a wiring portion 286 formed of a plurality of wirings.

The pixel portion 284 includes a plurality of pixels 284a arranged periodically. An enlarged view of one pixel 284a is illustrated on the right side of FIG. 30B. The pixel 284a can employ any of the structures described in the above embodiments. FIG. 30B illustrates an example in which a structure similar to that of the pixel 110 illustrated in FIG. 1A is employed.

The pixel circuit portion 283 includes a plurality of pixel circuits 283a arranged periodically.

One pixel circuit 283a is a circuit that controls driving of a plurality of elements included in one pixel 284a. One pixel circuit 283a can be provided with three circuits each controlling light emission of one light-emitting device. For example, the pixel circuit 283a can include at least one selection transistor, one current control transistor (driving transistor), and a capacitor for one light-emitting device. In that case, a gate signal is input to a gate of the selection transistor, and a source signal is input to a source of the selection transistor. Thus, an active-matrix display device is achieved.

The circuit portion 282 includes a circuit for driving the pixel circuits 283a in the pixel circuit portion 283. For example, the circuit portion 282 preferably includes one or both of a gate line driver circuit and a source line driver circuit. The circuit portion 282 may also include at least one of an arithmetic circuit, a memory circuit, a power supply circuit, and the like.

The FPC 290 functions as a wiring for supplying a video signal, a power supply potential, or the like to the circuit portion 282 from the outside. An IC may be mounted on the FPC 290.

The display module 280 can have a structure in which one or both of the pixel circuit portion 283 and the circuit portion 282 are stacked below the pixel portion 284; hence, the aperture ratio (the effective display area ratio) of the display portion 281 can be significantly high. For example, the aperture ratio of the display portion 281 can be greater than or equal to 40% and less than 100%, preferably greater than or equal to 50% and less than or equal to 95%, further preferably greater than or equal to 60% and less than or equal to 95%. Furthermore, the pixels 284a can be arranged extremely densely and thus the display portion 281 can have an extremely high resolution. For example, the pixels 284a are preferably arranged in the display portion 281 with a resolution higher than or equal to 2000 ppi, preferably higher than or equal to 3000 ppi, further preferably higher than or equal to 5000 ppi, still further preferably higher than or equal to 6000 ppi, and lower than or equal to 20000 ppi or lower than or equal to 30000 ppi.

Such a display module 280 has an extremely high resolution, and thus can be suitably used for a VR device such as an HMD or a glasses-type AR device. For example, even with a structure in which the display portion of the display module 280 is seen through a lens, pixels of the extremely-high-resolution display portion 281 included in the display module 280 are prevented from being perceived when the display portion is enlarged by the lens, so that display providing a high sense of immersion can be performed. Without being limited thereto, the display module 280 can be suitably used for electronic devices including a relatively small display portion. For example, the display module 280 can be suitably used for a display portion of a wearable electronic device such as a wrist watch.

[Display Device 100A]

The display device 100A illustrated in FIG. 31A includes a substrate 301, the light-emitting device 130R, the light-emitting device 130G, the light-emitting device 130B, a capacitor 240, and a transistor 310.

The substrate 301 corresponds to the substrate 291 in FIG. 30A and FIG. 30B. A stacked-layer structure from the substrate 301 to the insulating layer 255c corresponds to the layer 101 in Embodiment 1.

The transistor 310 is a transistor including a channel formation region in the substrate 301. As the substrate 301, a semiconductor substrate such as a single crystal silicon substrate can be used, for example. The transistor 310 includes part of the substrate 301, a conductive layer 311, a low-resistance region 312, an insulating layer 313, and an insulating layer 314. The conductive layer 311 functions as a gate electrode. The insulating layer 313 is positioned between the substrate 301 and the conductive layer 311 and functions as a gate insulating layer. The low-resistance region 312 is a region where the substrate 301 is doped with an impurity, and functions as one of a source and a drain. The insulating layer 314 is provided to cover a side surface of the conductive layer 311.

An element isolation layer 315 is provided between two adjacent transistors 310 to be embedded in the substrate 301.

An insulating layer 261 is provided to cover the transistor 310, and the capacitor 240 is provided over the insulating layer 261.

The capacitor 240 includes a conductive layer 241, a conductive layer 245, and an insulating layer 243 positioned between these conductive layers. The conductive layer 241 functions as one electrode of the capacitor 240, the conductive layer 245 functions as the other electrode of the capacitor 240, and the insulating layer 243 functions as a dielectric of the capacitor 240.

The conductive layer 241 is provided over the insulating layer 261 and is embedded in an insulating layer 254. The conductive layer 241 is electrically connected to one of the source and the drain of the transistor 310 through a plug 271 embedded in the insulating layer 261. The insulating layer 243 is provided to cover the conductive layer 241. The conductive layer 245 is provided in a region overlapping with the conductive layer 241 with the insulating layer 243 therebetween.

Note that a conductive layer surrounding the outer surface of the display portion 281 (or the pixel portion 284) is preferably provided in at least one layer of the conductive layers included in the layer 101. The conductive layer can also be referred to as a guard ring. By providing the conductive layer, elements such as a transistor and a light-emitting device can be inhibited from being broken by high voltage application due to ESD (electrostatic discharge) or charging caused by a step using plasma.

The insulating layer 255a is provided to cover the capacitor 240, the insulating layer 255b is provided over the insulating layer 255a, and the insulating layer 255c is provided over the insulating layer 255b. The light-emitting device 130R, the light-emitting device 130G, and the light-emitting device 130B are provided over the insulating layer 255c. FIG. 31A illustrates an example in which the light-emitting device 130R, the light-emitting device 130G, and the light-emitting device 130B each have a structure similar to the stacked-layer structure illustrated in FIG. 1B. An insulator is provided in a region between adjacent light-emitting devices. In FIG. 31A and the like, the insulating layer 125 and the insulating layer 127 over the insulating layer 125 are provided in this region.

The mask layer 118R is positioned over the layer 113R included in the light-emitting device 130R, the mask layer 118G is positioned over the layer 113G included in the light-emitting device 130G, and the mask layer 118B is positioned over the layer 113B included in the light-emitting device 130B.

The conductive layer 111R, the conductive layer 111G, and the conductive layer 111B are each electrically connected to one of the source and the drain of the transistor 310 through a plug 256 embedded in the insulating layer 243, the insulating layer 255a, the insulating layer 255b, and the insulating layer 255c, the conductive layer 241 embedded in the insulating layer 254, and the plug 271 embedded in the insulating layer 261. The top surface of the insulating layer 255c and the top surface of the plug 256 are level or substantially level with each other. A variety of conductive materials can be used for the plugs. FIG. 31A and the like illustrate an example in which the pixel electrodes (the conductive layer 111R, the conductive layer 111G, and the conductive layer 111B) each have a two-layer stacked structure.

The protective layer 131 is provided over the light-emitting device 130R, the light-emitting device 130G, and the light-emitting device 130B. The substrate 120 is bonded onto the protective layer 131 with the resin layer 122. Embodiment 1 can be referred to for the details of the light-emitting devices and the components thereover up to the substrate 120. The substrate 120 corresponds to the substrate 292 in FIG. 30A.

The display devices illustrated in FIG. 31B and FIG. 31C are each an example in which the light-emitting device 130R, the light-emitting device 130G, and the light-receiving device 150 are included. Although not illustrated, the display device also includes the light-emitting device 130B. In FIG. 31B and FIG. 31C, the layers below the insulating layer 255a are omitted. The display devices illustrated in FIG. 31B and FIG. 31C can each employ any of the structures of the layer 101, which are illustrated in FIG. 31A and FIG. 32 to FIG. 36, for example.

The light-receiving device 150 includes the conductive layer 111S, the layer 113S, the common layer 114, and the common electrode 115 which are stacked. The sidewall insulating layer 107S_1 is provided in contact with the side surfaces of the conductive layer 111S and the layer 113S. The sidewall insulating layer 107S_2 is provided in contact with the side surface of the sidewall insulating layer 107S_1 that is opposite to the side surface thereof in contact with the conductive layer 111S and the layer 113S. A sidewall insulating layer 107S_3 is provided in contact with the side surface of the sidewall insulating layer 107S_2 that is opposite to the side surface thereof in contact with the sidewall insulating layer 107S_1. Embodiment 1 and Embodiment 6 can be referred to for the details of the display device including the light-receiving device.

As illustrated in FIG. 31C, the lenses 133 may be provided in the display device. The lenses 133 can be provided to overlap with one or both of a light-emitting device and a light-receiving device.

FIG. 31C illustrates an example in which the lenses 133 are provided over the light-emitting device 130R, the light-emitting device 130G, and the light-receiving device 150 with the protective layer 131 therebetween. The lenses 133 are directly formed over the substrate provided with the light-emitting device (and the light-receiving device), whereby the accuracy of positional alignment of the light-emitting device or the light-receiving device and the lenses 133 can be improved.

In FIG. 31C, light emitted from the light-emitting device passes through the lenses 133 and is extracted to the outside of the display device.

Alternatively, the substrate 120 may be provided with the lenses 133, and the substrate 120 may be bonded onto the protective layer 131 with the resin layer 122. By providing the lenses 133 for the substrate 120, the heat treatment temperature in the formation step of the lenses 133 can be increased.

The lens 133 may include a convex surface facing either the substrate 120 side or the light-emitting device side. In view of the easiness of fabrication, the lens 133 provided on the light-emitting device side preferably includes a convex surface facing the substrate 120 side as illustrated in FIG. 31(C).

The lens 133 can be formed using at least one of an inorganic material and an organic material. For example, a material containing a resin can be used for the lens. Moreover, a material containing at least one of an oxide and a sulfide can be used for the lens. The lens 133 is preferably formed using a material having a higher refractive index than the resin layer 122. As the lens 133, a microlens array can be used, for example. The lens 133 may be directly formed over the substrate or the light-emitting device; alternatively, the lens 133 separately formed may be bonded thereto.

[Display Device 100B]

The display device 100B illustrated in FIG. 32 has a structure in which a transistor 310A and a transistor 310B whose channels are formed in a semiconductor substrate are stacked. Note that in the description of the display device below, portions similar to those of the above-described display device are not described in some cases.

The display device 100B has a structure in which a substrate 301B provided with the transistor 310B, the capacitor 240, and the light-emitting devices is bonded to a substrate 301A provided with the transistor 310A.

Here, an insulating layer 345 is preferably provided on the bottom surface of the substrate 301B (the surface on the substrate 301A side). An insulating layer 346 is preferably provided over the insulating layer 261 provided over the substrate 301A. The insulating layer 345 and the insulating layer 346 are insulating layers functioning as protective layers and can inhibit diffusion of impurities into the substrate 301B and the substrate 301A. For the insulating layer 345 and the insulating layer 346, an inorganic insulating film that can be used as the protective layer 131 can be used.

The substrate 301B is provided with a plug 343 that penetrates the substrate 301B and the insulating layer 345. Here, an insulating layer 344 is preferably provided to cover the side surface of the plug 343. The insulating layer 344 is an insulating layer functioning as a protective layer and can inhibit diffusion of impurities into the substrate 301B from the plug 343. As the insulating layer 344, an inorganic insulating film that can be used as the protective layer 131 can be used.

A conductive layer 342 is provided under the insulating layer 345 on the rear surface of the substrate 301B (the surface opposite to the substrate 120). The conductive layer 342 is preferably provided to be embedded in an insulating layer 335. The bottom surfaces of the conductive layer 342 and the insulating layer 335 (the surfaces on the substrate 301A side) are preferably planarized. Here, the conductive layer 342 is electrically connected to the plug 343.

Meanwhile, a conductive layer 341 is provided over the insulating layer 346 over the substrate 301A. The conductive layer 341 is preferably provided to be embedded in an insulating layer 336. The top surfaces of the conductive layer 341 and the insulating layer 336 are preferably planarized.

The conductive layer 341 and the conductive layer 342 are bonded to each other, whereby the substrate 301A and the substrate 301B are electrically connected to each other. Here, improving the flatness of a plane formed by the conductive layer 342 and the insulating layer 335 and a plane formed by the conductive layer 341 and the insulating layer 336 allows the conductive layer 341 and the conductive layer 342 to be bonded to each other favorably.

The conductive layer 341 and the conductive layer 342 are preferably formed using the same conductive material. For example, it is possible to use a metal film containing an element selected from Al, Cr, Cu, Ta, Ti, Mo, and W, or a metal nitride film containing any of the above elements as a component (a titanium nitride film, a molybdenum nitride film, or a tungsten nitride film). Copper is particularly preferably used for the conductive layer 341 and the conductive layer 342. In that case, it is possible to employ Cu—Cu (copper-to-copper) direct bonding (a technique for achieving electrical continuity by connecting Cu (copper) pads).

[Display Device 100C]

The display device 100C illustrated in FIG. 33 has a structure in which the conductive layer 341 and the conductive layer 342 are bonded to each other through a bump 347.

As illustrated in FIG. 33, providing the bump 347 between the conductive layer 341 and the conductive layer 342 enables the conductive layer 341 and the conductive layer 342 to be electrically connected to each other. The bump 347 can be formed using a conductive material containing gold (Au), nickel (Ni), indium (In), tin (Sn), or the like, for example. For another example, solder may be used for the bump 347. An adhesive layer 348 may be provided between the insulating layer 345 and the insulating layer 346. In the case where the bump 347 is provided, the insulating layer 335 and the insulating layer 336 illustrated in FIG. 32 may be omitted.

[Display Device 100D]

The display device 100D illustrated in FIG. 34 differs from the display device 100A mainly in a transistor structure.

A transistor 320 is a transistor that includes a metal oxide (also referred to as an oxide semiconductor) in its semiconductor layer where a channel is formed (i.e., an OS transistor).

The transistor 320 includes a semiconductor layer 321, an insulating layer 323, a conductive layer 324, a pair of conductive layers 325, an insulating layer 326, and a conductive layer 327.

A substrate 331 corresponds to the substrate 291 in FIG. 30A and FIG. 30B. A stacked-layer structure from the substrate 331 to the insulating layer 255c corresponds to the layer 101 in Embodiment 1. As the substrate 331, an insulating substrate or a semiconductor substrate can be used.

An insulating layer 332 is provided over the substrate 331. The insulating layer 332 functions as a barrier layer that prevents diffusion of impurities such as water and hydrogen from the substrate 331 into the transistor 320 and release of oxygen from the semiconductor layer 321 to the substrate 331 side. As the insulating layer 332, for example, a film in which hydrogen or oxygen is less likely to diffuse than in a silicon oxide film, such as an aluminum oxide film, a hafnium oxide film, or a silicon nitride film, can be used.

The conductive layer 327 is provided over the insulating layer 332, and the insulating layer 326 is provided to cover the conductive layer 327. The conductive layer 327 functions as a first gate electrode of the transistor 320, and part of the insulating layer 326 functions as a first gate insulating layer. An oxide insulating film such as a silicon oxide film is preferably used as at least part of the insulating layer 326 that is in contact with the semiconductor layer 321. The top surface of the insulating layer 326 is preferably planarized.

The semiconductor layer 321 is provided over the insulating layer 326. The semiconductor layer 321 preferably includes a metal oxide (also referred to as oxide semiconductor) film having semiconductor characteristics. The pair of conductive layers 325 are provided over and in contact with the semiconductor layer 321 and function as a source electrode and a drain electrode.

An insulating layer 328 is provided to cover the top surfaces and side surfaces of the pair of conductive layers 325, the side surface of the semiconductor layer 321, and the like, and an insulating layer 264 is provided over the insulating layer 328. The insulating layer 328 functions as a barrier layer that prevents diffusion of impurities such as water and hydrogen from the insulating layer 264 and the like into the semiconductor layer 321 and release of oxygen from the semiconductor layer 321. As the insulating layer 328, an insulating film similar to the insulating layer 332 can be used.

An opening reaching the semiconductor layer 321 is provided in the insulating layer 328 and the insulating layer 264. The insulating layer 323 that is in contact with the side surfaces of the insulating layer 264, the insulating layer 328, and the conductive layer 325 and the top surface of the semiconductor layer 321, and the conductive layer 324 are embedded in the opening. The conductive layer 324 functions as a second gate electrode, and the insulating layer 323 functions as a second gate insulating layer.

The top surface of the conductive layer 324, the top surface of the insulating layer 323, and the top surface of the insulating layer 264 are planarized so as to be level or substantially level with each other, and an insulating layer 329 and an insulating layer 265 are provided to cover these layers.

The insulating layer 264 and the insulating layer 265 function as interlayer insulating layers. The insulating layer 329 functions as a barrier layer that prevents diffusion of impurities such as water and hydrogen from the insulating layer 265 and the like into the transistor 320. For the insulating layer 329, an insulating film similar to the insulating layer 328 and the insulating layer 332 can be used.

A plug 274 electrically connected to one of the pair of conductive layers 325 is provided to be embedded in the insulating layer 265, the insulating layer 329, and the insulating layer 264. Here, the plug 274 preferably includes a conductive layer 274a covering the side surface of an opening formed in the insulating layer 265, the insulating layer 329, the insulating layer 264, and the insulating layer 328 and part of the top surface of the conductive layer 325, and a conductive layer 274b in contact with the top surface of the conductive layer 274a. For the conductive layer 274a, a conductive material that does not easily allow diffusion of hydrogen and oxygen is preferably used.

[Display Device 100E]

The display device 100E illustrated in FIG. 35 has a structure in which a transistor 320A and a transistor 320B each including an oxide semiconductor in a semiconductor where a channel is formed are stacked.

The display device 100D can be referred to for the transistor 320A, the transistor 320B, and the components around them.

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

[Display Device 100F]

The display device 100F illustrated in FIG. 36 has a structure in which the transistor 310 having a channel formed in the substrate 301 and the transistor 320 including a metal oxide in a semiconductor layer where a channel is formed are stacked.

The insulating layer 261 is provided to cover the transistor 310, and a conductive layer 251 is provided over the insulating layer 261. An insulating layer 262 is provided to cover the conductive layer 251, and a conductive layer 252 is provided over the insulating layer 262. The conductive layer 251 and the conductive layer 252 each function as a wiring. An insulating layer 263 and the insulating layer 332 are provided to cover the conductive layer 252, and the transistor 320 is provided over the insulating layer 332. The insulating layer 265 is provided to cover the transistor 320, and the capacitor 240 is provided over the insulating layer 265. The capacitor 240 and the transistor 320 are electrically connected to each other through the plug 274.

The transistor 320 can be used as a transistor included in the pixel circuit. The transistor 310 can be used as a transistor included in the pixel circuit or a transistor included in a driver circuit (a gate line driver circuit or a source line driver circuit) for driving the pixel circuit. The transistor 310 and the transistor 320 can also be used as transistors included in a variety of circuits such as an arithmetic circuit and a memory circuit.

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

[Display Device 100G]

FIG. 37 is a perspective view of a display device 100G, and FIG. 38A is a cross-sectional view of the display device 100G.

In the display device 100G, a substrate 152 and a substrate 151 are bonded to each other. In FIG. 37, the substrate 152 is denoted by a dashed line.

The display device 100G includes a display portion 162, the connection portion 140, a circuit 164, a wiring 165, and the like. FIG. 37 illustrates an example in which an IC 173 and an FPC 172 are mounted on the display device 100G. Thus, the structure illustrated in FIG. 37 can also be regarded as a display module including the display device 100G, the IC (integrated circuit), and the FPC.

The connection portion 140 is provided outside the display portion 162. The connection portion 140 can be provided along one or more sides of the display portion 162. The number of connection portions 140 may be one or more. FIG. 37 illustrates an example in which the connection portion 140 is provided to surround the four sides of the display portion. A common electrode of a light-emitting device is electrically connected to a conductive layer in the connection portion 140, so that a potential can be supplied to the common electrode.

As the circuit 164, a scan line driver circuit can be used, for example.

The wiring 165 has a function of supplying a signal and power to the display portion 162 and the circuit 164. The signal and the power are input to the wiring 165 from the outside through the FPC 172 or input to the wiring 165 from the IC 173.

FIG. 37 illustrates an example in which the IC 173 is provided over the substrate 151 by a COG (Chip On Glass) method, a COF (Chip On Film) method, or the like. An IC including a scan line driver circuit, a signal line driver circuit, or the like can be used as the IC 173, for example. Note that the display device 100G and the display module are not necessarily provided with an IC. The IC may be mounted on the FPC by a COF method or the like.

FIG. 38A illustrates an example of cross sections of part of a region including the FPC 172, part of the circuit 164, part of the display portion 162, part of the connection portion 140, and part of a region including an end portion of the display device 100G.

The display device 100G illustrated in FIG. 38A includes a transistor 201, a transistor 205, the light-emitting device 130R emitting red light, the light-emitting device 130G emitting green light, the light-emitting device 130B emitting blue light, and the like between the substrate 151 and the substrate 152.

The light-emitting device 130R, the light-emitting device 130G, and the light-emitting device 130B each have a structure similar to the stacked-layer structure illustrated in FIG. 1B except the structure of the pixel electrode. Embodiment 1 can be referred to for the details of the light-emitting devices.

The light-emitting device 130R includes a conductive layer 112R, a conductive layer 126R over the conductive layer 112R, and a conductive layer 129R over the conductive layer 126R. All of the conductive layer 112R, the conductive layer 126R, and the conductive layer 129R can be referred to as pixel electrodes, or some of them can be referred to as pixel electrodes.

The light-emitting device 130G includes a conductive layer 112G, a conductive layer 126G over the conductive layer 112G, and a conductive layer 129G over the conductive layer 126G.

The light-emitting device 130B includes a conductive layer 112B, a conductive layer 126B over the conductive layer 112B, and a conductive layer 129B over the conductive layer 126B.

The conductive layer 112R is connected to a conductive layer 222b included in the transistor 205 through an opening provided in an insulating layer 214. The end portion of the conductive layer 112R, the end portion of the conductive layer 126R, and the end portion of the conductive layer 129R are aligned or substantially aligned with each other. For example, a conductive layer functioning as a reflective electrode can be used as the conductive layer 112R and the conductive layer 126R, and a conductive layer functioning as a transparent electrode can be used as the conductive layer 129R.

Detailed description of the conductive layer 112G, the conductive layer 126G, and the conductive layer 129G of the light-emitting device 130G and the conductive layer 112B, the conductive layer 126B, and the conductive layer 129B of the light-emitting device 130B is omitted because these conductive layers are similar to the conductive layer 112R, the conductive layer 126R, and the conductive layer 129R of the light-emitting device 130R.

Depressed portions are formed in the conductive layer 112R, the conductive layer 112G, and the conductive layer 112B so as to cover the openings provided in the insulating layer 214. A layer 128 is embedded in each of the depressed portions.

The layer 128 has a function of filling the depressed portions of the conductive layer 112R, the conductive layer 112G, and the conductive layer 112B. The conductive layer 126R, the conductive layer 126G, and the conductive layer 126B electrically connected to the conductive layer 112R, the conductive layer 112G, and the conductive layer 112B, respectively, are provided over the conductive layer 112R, the conductive layer 112G, the conductive layer 112B, and the layer 128. Thus, regions overlapping with the depressed portions of the conductive layer 112R, the conductive layer 112G, and the conductive layer 112B can also be used as light-emitting regions, increasing the aperture ratio of the pixels.

The layer 128 may be an insulating layer or a conductive layer. Any of a variety of inorganic insulating materials, organic insulating materials, and conductive materials can be used for the layer 128 as appropriate. Specifically, the layer 128 is preferably formed using an insulating material and is particularly preferably formed using an organic insulating material. For the layer 128, an organic insulating material that can be used for the insulating layer 127 can be used, for example.

The side surfaces of the conductive layer 112R, the conductive layer 126R, the conductive layer 129R, and the layer 113R are aligned or substantially aligned with each other, and the side surfaces are in contact with the sidewall insulating layer 107R_1. The side surfaces of the conductive layer 112G, the conductive layer 126G, the conductive layer 129G, and the layer 113G are aligned or substantially aligned with each other, and the side surfaces are in contact with the sidewall insulating layer 107G_1. Similarly, the side surfaces of the conductive layer 112B, the conductive layer 126B, the conductive layer 129B, and the layer 113B are aligned or substantially aligned with each other, and the side surfaces are in contact with the sidewall insulating layer 107B_1. The sidewall insulating layer 107G_2 is in contact with the side surface of the sidewall insulating layer 107G_1 (the surface opposite to the surface thereof in contact with the conductive layer 112G, the conductive layer 126G, the conductive layer 129G, and the layer 113G). The sidewall insulating layer 107B_2 is in contact with the side surface of the sidewall insulating layer 107B_1 (the surface opposite to the surface thereof in contact with the conductive layer 112B, the conductive layer 126B, the conductive layer 129B, and the layer 113B), and the sidewall insulating layer 107B_3 is in contact with the side surface of the sidewall insulating layer 107B_2 (the surface opposite to the surface thereof in contact with the sidewall insulating layer 107B_1).

The side surface and part of the top surface of each of the layer 113B, the layer 113G, and the layer 113R are covered with the insulating layer 125 and the insulating layer 127. The mask layer 118B is positioned between the layer 113B and the insulating layer 125. The mask layer 118G is positioned between the layer 113G and the insulating layer 125, and the mask layer 118R is positioned between the layer 113R and the insulating layer 125. The common layer 114 is provided over the layer 113B, the layer 113G, the layer 113R, the insulating layer 125, and the insulating layer 127, and the common electrode 115 is provided over the common layer 114. The common layer 114 and the common electrode 115 are each a continuous film provided to be shared by a plurality of light-emitting devices.

The protective layer 131 is provided over the light-emitting device 130R, the light-emitting device 130G, and the light-emitting device 130B. The protective layer 131 and the substrate 152 are bonded to each other with an adhesive layer 142. The substrate 152 is provided with a light-blocking layer 117. A solid sealing structure, a hollow sealing structure, or the like can be employed to seal the light-emitting devices. In FIG. 38A, a solid sealing structure is employed in which a space between the substrate 152 and the substrate 151 is filled with the adhesive layer 142. Alternatively, a hollow sealing structure may be employed in which the space is filled with an inert gas (e.g., nitrogen or argon). Here, the adhesive layer 142 may be provided not to overlap with the light-emitting device. The space may be filled with a resin different from that of the frame-like adhesive layer 142.

The protective layer 131 is provided at least in the display portion 162, and preferably provided to cover the entire display portion 162. The protective layer 131 is preferably provided to cover not only the display portion 162 but also the connection portion 140 and the circuit 164. It is also preferable that the protective layer 131 be provided to extend to an end portion of the display device 100G. Meanwhile, a connection portion 204 has a portion not provided with the protective layer 131 so that the FPC 172 and a conductive layer 166 are electrically connected to each other.

The connection portion 204 is provided in a region of the substrate 151 not overlapping with the substrate 152. In the connection portion 204, the wiring 165 is electrically connected to the FPC 172 through the conductive layer 166 and a connection layer 242. In the illustrated example, the conductive layer 166 has a stacked-layer structure of a conductive layer obtained by processing the same conductive film as the conductive layer 112R, the conductive layer 112G, and the conductive layer 112B, a conductive layer obtained by processing the same conductive film as the conductive layer 126R, the conductive layer 126G, and the conductive layer 126B, and a conductive layer obtained by processing the same conductive film as the conductive layer 129R, the conductive layer 129G, and the conductive layer 129B. On the top surface of the connection portion 204, the conductive layer 166 is exposed. Thus, the connection portion 204 and the FPC 172 can be electrically connected to each other through the connection layer 242.

For example, the protective layer 131 is formed over the entire surface of the display device 100G and then a region of the protective layer 131 overlapping with the conductive layer 166 is removed, so that the conductive layer 166 can be exposed.

A stacked-layer structure of at least one organic layer and a conductive layer may be provided over the conductive layer 166, and the protective layer 131 may be provided over the stacked-layer structure. Then, a separation trigger (a portion that can be a trigger of separation) may be formed in the stacked-layer structure using a laser or a sharp cutter (e.g., a needle or a utility knife) to selectively remove the stacked-layer structure and the protective layer 131 thereover, so that the conductive layer 166 may be exposed. For example, the protective layer 131 can be selectively removed when an adhesive roller is pressed to the substrate 151 and then moved relatively while being rolled. Alternatively, an adhesive tape may be attached to the substrate 151 and then peeled. Since the adhesion between the organic layer and the conductive layer or between the organic layers is low, separation occurs at the interface between the organic layer and the conductive layer or in the organic layer. Thus, a region of the protective layer 131 overlapping with the conductive layer 166 can be selectively removed. Note that when the organic layer and the like remain over the conductive layer 166, the remaining organic layer and the like can be removed by an organic solvent or the like.

As the organic layer, it is possible to use at least one of the organic layers (the layer functioning as the light-emitting layer, the carrier-blocking layer, the carrier-transport layer, or the carrier-injection layer) used for the layer 113B, the layer 113G, and the layer 113R, for example. The organic layer may be formed concurrently with the layer 113B, the layer 113G, and the layer 113R, or may be provided separately. The conductive layer can be formed using the same step and the same material as those for the common electrode 115. An ITO film is preferably formed as the common electrode 115 and the conductive layer, for example. Note that in the case where a stacked-layer structure is used for the common electrode 115, at least one of the layers included in the common electrode 115 is provided as the conductive layer.

The top surface of the conductive layer 166 may be covered with a mask so that the protective layer 131 is not provided over the conductive layer 166. As the mask, a metal mask (an area metal mask) or a tape or a film having adhesiveness or attachability may be used. The protective layer 131 is formed while the mask is placed and then the mask is removed, so that the conductive layer 166 can be kept exposed even after the protective layer 131 is formed.

With such a method, a region not provided with the protective layer 131 can be formed in the connection portion 204, and the conductive layer 166 and the FPC 172 can be electrically connected to each other through the connection layer 242 in the region.

The conductive layer 123 is provided over the insulating layer 214 in the connection portion 140. In the illustrated example, the conductive layer 123 has a stacked-layer structure of a conductive layer obtained by processing the same conductive film as the conductive layer 112R, the conductive layer 112G, and the conductive layer 112B, a conductive layer obtained by processing the same conductive film as the conductive layer 126R, the conductive layer 126G, and the conductive layer 126B, and a conductive layer obtained by processing the same conductive film as the conductive layer 129R, the conductive layer 129G, and the conductive layer 129B. The end portion of the conductive layer 123 is covered with the mask layer 118B, the insulating layer 125, the insulating layer 127, and the like. The common layer 114 is provided over the conductive layer 123, and the common electrode 115 is provided over the common layer 114. The conductive layer 123 and the common electrode 115 are electrically connected to each other through the common layer 114. Note that the common layer 114 is not necessarily formed in the connection portion 140. In that case, the conductive layer 123 and the common electrode 115 are in direct contact with each other to be electrically connected to each other.

The display device 100G has a top-emission structure. Light emitted from the light-emitting device is emitted toward the substrate 152 side. For the substrate 152, a material having a high visible-light-transmitting property is preferably used. The pixel electrode contains a material reflecting visible light, and the counter electrode (the common electrode 115) contains a material transmitting visible light.

A stacked-layer structure from the substrate 151 to the insulating layer 214 corresponds to the layer 101 in Embodiment 1.

The transistor 201 and the transistor 205 are formed over the substrate 151. These transistors can be fabricated using the same material in the same step.

An insulating layer 211, an insulating layer 213, an insulating layer 215, and the insulating layer 214 are provided in this order over the substrate 151. Part of the insulating layer 211 functions as a gate insulating layer of each transistor. Part of the insulating layer 213 functions as a gate insulating layer of each transistor. The insulating layer 215 is provided to cover the transistors. The insulating layer 214 is provided to cover the transistors and has a function of a planarization layer. Note that the number of gate insulating layers and the number of insulating layers covering the transistors are not limited and may each be one or two or more.

A material that does not easily allow diffusion of impurities such as water and hydrogen is preferably used for at least one of the insulating layers that cover the transistors. This allows the insulating layer to function as a barrier layer. Such a structure can effectively inhibit diffusion of impurities into the transistors from the outside and improve the reliability of the display device.

An inorganic insulating film is preferably used as each of the insulating layer 211, the insulating layer 213, and the insulating layer 215. As the inorganic insulating film, a silicon nitride film, a silicon oxynitride film, a silicon oxide film, a silicon nitride oxide film, an aluminum oxide film, an aluminum nitride film, or the like can be used, for example. A hafnium oxide film, an yttrium oxide film, a zirconium oxide film, a gallium oxide film, a tantalum oxide film, a magnesium oxide film, a lanthanum oxide film, a cerium oxide film, a neodymium oxide film, or the like may also be used. A stack including two or more of the above insulating films may also be used.

An organic insulating layer is suitable as the insulating layer 214 functioning as a planarization layer. Examples of materials that can be used for the organic insulating layer include an acrylic resin, a polyimide resin, an epoxy resin, a polyamide resin, a polyimide-amide resin, a siloxane resin, a benzocyclobutene-based resin, a phenol resin, and precursors of these resins. The insulating layer 214 may have a stacked-layer structure of an organic insulating layer and an inorganic insulating layer. The outermost layer of the insulating layer 214 preferably has a function of an etching protective layer. Accordingly, a depressed portion can be inhibited from being formed in the insulating layer 214 in processing the conductive layer 112R, the conductive layer 126R, the conductive layer 129R, or the like. Alternatively, a depressed portion may be provided in the insulating layer 214 in processing the conductive layer 112R, the conductive layer 126R, the conductive layer 129R, or the like.

Each of the transistor 201 and the transistor 205 includes a conductive layer 221 functioning as a gate electrode, the insulating layer 211 functioning as a gate insulating layer, a conductive layer 222a and the conductive layer 222b functioning as a source electrode and a drain electrode, a semiconductor layer 231, the insulating layer 213 functioning as a gate insulating layer, and a conductive layer 223 functioning as a gate electrode. Here, a plurality of layers obtained by processing the same conductive film are shown with the same hatching pattern. The insulating layer 211 is positioned between the conductive layer 221 and the semiconductor layer 231. The insulating layer 213 is positioned between the conductive layer 223 and the semiconductor layer 231.

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

The structure in which the semiconductor layer where a channel is formed is provided between two gate electrodes is used for the transistor 201 and the transistor 205. The two gate electrodes may be connected to each other and supplied with the same signal to drive the transistor. Alternatively, a potential for controlling the threshold voltage may be supplied to one of the two gate electrodes and a potential for driving may be supplied to the other to control the threshold voltage of the transistor.

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

The semiconductor layer of the transistor preferably includes a metal oxide (also referred to as an oxide semiconductor). That is, a transistor including a metal oxide in its channel formation region (hereinafter, an OS transistor) is preferably used for the display device of this embodiment.

Examples of the metal oxide that can be used for the semiconductor layer include indium oxide, gallium oxide, and zinc oxide. The metal oxide preferably contains two or three selected from indium, the element M, and zinc. The element M is one or more kinds selected from gallium, aluminum, silicon, boron, yttrium, tin, copper, vanadium, beryllium, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, and magnesium. Specifically, the element M is preferably one or more kinds selected from aluminum, gallium, yttrium, and tin.

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

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

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

The semiconductor layer may include two or more metal oxide layers having different compositions. For example, a stacked-layer structure of a first metal oxide layer with In:M:Zn=1:3:4 [atomic ratio] or a composition in the neighborhood thereof and a second metal oxide layer with In:M:Zn=1:1:1 [atomic ratio] or a composition in the neighborhood thereof and being provided over the first metal oxide layer can be suitably employed. It is particularly preferable to use gallium or aluminum as the element M.

For another example, a stacked-layer structure of one selected from indium oxide, indium gallium oxide, and IGZO and one selected from IAZO, IAGZO, and ITZO (registered trademark) may be employed.

Examples of the oxide semiconductor having crystallinity include a CAAC (C-Axis-Aligned Crystalline)-OS and an nc (nanocrystalline)-OS.

Alternatively, a transistor using silicon in a channel formation region (a Si transistor) may be used. Examples of silicon include single crystal silicon, polycrystalline silicon, and amorphous silicon. In particular, a transistor containing low-temperature polysilicon (LTPS) in its semiconductor layer (hereinafter, also referred to as an LTPS transistor) is preferably used. The LTPS transistor has high field-effect mobility and excellent frequency characteristics.

With the use of a Si transistor such as an LTPS transistor, a circuit required to be driven at a high frequency (e.g., a source driver circuit) can be formed on the same substrate as the display portion. This allows simplification of an external circuit mounted on the display device and a reduction in component cost and mounting cost.

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

To increase the emission luminance of the light-emitting device included in a pixel circuit, it is necessary to increase the amount of current flowing through the light-emitting device. For that purpose, the source-drain voltage of a driving transistor included in the pixel circuit needs to be increased. Since an OS transistor has a higher withstand voltage between the source and the drain than a Si transistor, a high voltage can be applied between the source and the drain of the OS transistor. Thus, by using an OS transistor as the driving transistor included in the pixel circuit, the amount of current flowing through the light-emitting device can be increased, resulting in an increase in emission luminance of the light-emitting device.

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

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

As described above, by using an OS transistor as the driving transistor included in the pixel circuit, it is possible to achieve “inhibition of black floating”, “increase in emission luminance”, “increase in the number of gray levels”, “inhibition of variation in light-emitting devices”, and the like.

The transistors included in the circuit 164 and the transistors included in the display portion 162 may have the same structure or different structures. A plurality of transistors included in the circuit 164 may have the same structure or two or more kinds of structures. Similarly, a plurality of transistors included in the display portion 162 may have the same structure or two or more kinds of structures.

All of the transistors included in the display portion 162 may be OS transistors or all of the transistors included in the display portion 162 may be Si transistors; alternatively, some of the transistors included in the display portion 162 may be OS transistors and the others may be Si transistors.

For example, when both an LTPS transistor and an OS transistor are used in the display portion 162, the display device can have low power consumption and high drive capability. A structure in which an LTPS transistor and an OS transistor are used in combination is referred to as LTPO in some cases. For a more suitable example, it is preferable that the OS transistor be used as a transistor or the like functioning as a switch for controlling conduction or non-conduction between wirings and that the LTPS transistor be used as a transistor or the like for controlling current.

For example, one transistor included in the display portion 162 functions as a transistor for controlling current flowing through the light-emitting device and can also be referred to as a driving transistor. One of a source and a drain of the driving transistor is electrically connected to the pixel electrode of the light-emitting device. An LTPS transistor is preferably used as the driving transistor. Thus, current flowing through the light-emitting device in the pixel circuit can be increased.

By contrast, another transistor included in the display portion 162 functions as a switch for controlling selection or non-selection of a pixel and can also be referred to as a selection transistor. A gate of the selection transistor is electrically connected to a gate line, and one of a source and a drain thereof is electrically connected to a source line (a signal line). An OS transistor is preferably used as the selection transistor. Accordingly, the gray level of the pixel can be maintained even with an extremely low frame frequency (e.g., lower than or equal to 1 fps); thus, power consumption can be reduced by stopping the driver in displaying a still image.

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

Note that the display device of one embodiment of the present invention has a structure including the OS transistor and the light-emitting device having an MML (metal maskless) structure. This structure can significantly reduce the leakage current that might flow through a transistor, and the leakage current that might flow through a region (a light-emitting region) between adjacent light-emitting devices (also referred to as lateral leakage current, side leakage current, or the like). With the structure, a viewer can observe any one or more of image crispness, image sharpness, a high chroma, and a high contrast ratio in an image displayed on the display device. Note that when the leakage current that might flow through a transistor and the lateral leakage current between light-emitting devices are extremely low, light leakage (what is called black floating) or the like that might occur in black display can be reduced as much as possible.

In particular, in the case where a light-emitting device having the MML structure employs the above-described SBS structure, a layer provided between light-emitting devices (for example, an organic layer shared by the light-emitting devices, also referred to as a common layer) is disconnected; accordingly, side leakage can be eliminated or reduced as much as possible.

FIG. 38B and FIG. 38C illustrate other structure examples of transistors.

A transistor 209 and a transistor 210 each include the conductive layer 221 functioning as a gate electrode, the insulating layer 211 functioning as a gate insulating layer, the semiconductor layer 231 including a channel formation region 231i and a pair of low-resistance regions 231n, the conductive layer 222a connected to one of the pair of low-resistance regions 231n, the conductive layer 222b connected to the other of the pair of low-resistance regions 231n, an insulating layer 225 functioning as a gate insulating layer, the conductive layer 223 functioning as a gate electrode, and the insulating layer 215 covering the conductive layer 223. The insulating layer 211 is positioned between the conductive layer 221 and the channel formation region 231i. The insulating layer 225 is positioned between at least the conductive layer 223 and the channel formation region 231i. Furthermore, an insulating layer 218 covering the transistor may be provided.

FIG. 38B illustrates an example of the transistor 209 in which the insulating layer 225 covers the top surface and side surfaces of the semiconductor layer 231. The conductive layer 222a and the conductive layer 222b are connected to the low-resistance regions 231n through openings provided in the insulating layer 225 and the insulating layer 215. One of the conductive layer 222a and the conductive layer 222b functions as a source electrode, and the other functions as a drain electrode.

Meanwhile, in the transistor 210 illustrated in FIG. 38C, the insulating layer 225 overlaps with the channel formation region 231i of the semiconductor layer 231 and does not overlap with the low-resistance regions 231n. The structure illustrated in FIG. 38C can be formed by processing the insulating layer 225 using the conductive layer 223 as a mask, for example. In FIG. 38C, the insulating layer 215 is provided to cover the insulating layer 225 and the conductive layer 223, and the conductive layer 222a and the conductive layer 222b are connected to the low-resistance regions 231n through the openings in the insulating layer 215.

In the display device 100G illustrated in FIG. 38A, the light-blocking layer 117 is preferably provided on the surface of the substrate 152 that faces the substrate 151. The light-blocking layer 117 can be provided between adjacent light-emitting devices, in the connection portion 140, and in the circuit 164, for example. A variety of optical members can be arranged on the outer surface of the substrate 152.

The material that can be used for the substrate 120 illustrated in FIG. 1B and the like can be used for each of the substrate 151 and the substrate 152.

The material that can be used for the resin layer 122 illustrated in FIG. 1B and the like can be used for the adhesive layer 142.

As the connection layer 242, an anisotropic conductive film (ACF), an anisotropic conductive paste (ACP), or the like can be used.

[Display Device 100H]

A display device 100H illustrated in FIG. 39A is different from the display device 100G mainly in being a bottom-emission display device.

Light emitted from the light-emitting device is emitted toward the substrate 151 side. For the substrate 151, a material having a high visible-light-transmitting property is preferably used. By contrast, there is no limitation on the light-transmitting property of a material used for the substrate 152.

The light-blocking layer 117 is preferably formed between the substrate 151 and the transistor 201 and between the substrate 151 and the transistor 205. FIG. 39A illustrates an example in which the light-blocking layer 117 is provided over the substrate 151, an insulating layer 153 is provided over the light-blocking layer 117, and the transistor 201, the transistor 205, and the like are provided over the insulating layer 153.

The light-emitting device 130R includes the conductive layer 112R, the conductive layer 126R over the conductive layer 112R, and the conductive layer 129R over the conductive layer 126R.

The light-emitting device 130G includes the conductive layer 112G, the conductive layer 126G over the conductive layer 112G, and the conductive layer 129G over the conductive layer 126G.

Although not illustrated, the light-emitting device 130B includes the conductive layer 112B, the conductive layer 126B over the conductive layer 112B, and the conductive layer 129B over the conductive layer 126B.

A material having a high visible-light-transmitting property is used for each of the conductive layer 112R, the conductive layer 112G, the conductive layer 112B, the conductive layer 126R, the conductive layer 126G, the conductive layer 126B, the conductive layer 129R, the conductive layer 129G, and the conductive layer 129B. A material reflecting visible light is preferably used for the common electrode 115.

Although FIG. 38A, FIG. 39A, and the like illustrate an example in which the top surface of the layer 128 includes a flat portion, the shape of the layer 128 is not particularly limited. FIG. 39B to FIG. 39D illustrate variation examples of the layer 128.

As illustrated in FIG. 39B and FIG. 39D, the top surface of the layer 128 can have a shape such that its center and the vicinity thereof are recessed, i.e., a shape including a concave surface, in a cross-sectional view.

As illustrated in FIG. 39C, the top surface of the layer 128 can have a shape such that its center and the vicinity thereof bulge, i.e., a shape including a convex surface, in a cross-sectional view.

The top surface of the layer 128 may include one or both of a convex surface and a concave surface. The number of convex surfaces and the number of concave surfaces included in the top surface of the layer 128 are not limited and can each be one or more.

The level of the top surface of the layer 128 and the level of the top surface of the conductive layer 112R may be equal to or substantially equal to each other, or may be different from each other. For example, the level of the top surface of the layer 128 may be either lower or higher than the level of the top surface of the conductive layer 112R.

FIG. 39B can be regarded as illustrating an example in which the layer 128 fits in the depressed portion of the conductive layer 112R. By contrast, as illustrated in FIG. 39D, the layer 128 may exist also outside the depressed portion of the conductive layer 112R, that is, the layer 128 may be formed to have a top surface wider than the depressed portion.

[Display Device 1001]

A display device 1001 illustrated in FIG. 40 is different from the display device 100G mainly in including the light-receiving device 150.

The light-receiving device 150 includes a conductive layer 112S, a conductive layer 126S over the conductive layer 112S, and a conductive layer 129S over the conductive layer 126S.

The conductive layer 112S is connected to the conductive layer 222b included in the transistor 205 through an opening provided in the insulating layer 214.

The layer 113S is provided over the conductive layer 129S, the side surfaces of the conductive layer 112S, the conductive layer 126S, the conductive layer 129S, and the layer 113S are aligned or substantially aligned with each other, and the side surfaces are in contact with the sidewall insulating layer 107S_1. The layer 113S includes at least an active layer.

The side surface and part of the top surface of the layer 113S are covered with the insulating layer 125 and the insulating layer 127. The mask layer 118S is positioned between the layer 113S and the insulating layer 125. The common layer 114 is provided over the layer 113S, the insulating layer 125, and the insulating layer 127, and the common electrode 115 is provided over the common layer 114. The common layer 114 is a continuous film provided to be shared by the light-receiving device and the light-emitting devices.

The display device 100I can employ any of the pixel layouts that are described in Embodiment 3 with reference to FIG. 29A to FIG. 29K, for example. Embodiment 1 and Embodiment 6 can be referred to for the details of the display device including the light-receiving device.

This embodiment can be combined with any of the other embodiments as appropriate.

Embodiment 5

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

[Light-Emitting Device]

As illustrated in FIG. 41A, the light-emitting device includes an EL layer 763 between a pair of electrodes (a lower electrode 761 and an upper electrode 762). The EL layer 763 can be formed of a plurality of layers such as a layer 780, a light-emitting layer 771, and a layer 790.

The light-emitting layer 771 contains at least a light-emitting substance (also referred to as a light-emitting material).

In the case where the lower electrode 761 is an anode and the upper electrode 762 is a cathode, the layer 780 includes one or more of a layer containing a substance having a high hole-injection property (a hole-injection layer), a layer containing a substance having a high hole-transport property (a hole-transport layer), and a layer containing a substance having a high electron-blocking property (an electron-blocking layer). Furthermore, the layer 790 includes one or more of a layer containing a substance having a high electron-injection property (an electron-injection layer), a layer containing a substance having a high electron-transport property (an electron-transport layer), and a layer containing a substance having a high hole-blocking property (a hole-blocking layer). In the case where the lower electrode 761 is a cathode and the upper electrode 762 is an anode, the structures of the layer 780 and the layer 790 are replaced with each other.

The structure including the layer 780, the light-emitting layer 771, and the layer 790, which is provided between the pair of electrodes, can function as a single light-emitting unit, and the structure in FIG. 41A is referred to as a single structure in this specification.

FIG. 41B is a variation example of the EL layer 763 included in the light-emitting device illustrated in FIG. 41A. Specifically, the light-emitting device illustrated in FIG. 41B includes a layer 781 over the lower electrode 761, a layer 782 over the layer 781, the light-emitting layer 771 over the layer 782, a layer 791 over the light-emitting layer 771, a layer 792 over the layer 791, and the upper electrode 762 over the layer 792.

In the case where the lower electrode 761 is an anode and the upper electrode 762 is a cathode, the layer 781 can be a hole-injection layer, the layer 782 can be a hole-transport layer, the layer 791 can be an electron-transport layer, and the layer 792 can be an electron-injection layer, for example. In the case where the lower electrode 761 is a cathode and the upper electrode 762 is an anode, the layer 781 can be an electron-injection layer, the layer 782 can be an electron-transport layer, the layer 791 can be a hole-transport layer, and the layer 792 can be a hole-injection layer. With such a layered structure, carriers can be efficiently injected to the light-emitting layer 771, and the efficiency of the recombination of carriers in the light-emitting layer 771 can be enhanced.

Note that structures in which a plurality of light-emitting layers (the light-emitting layer 771, a light-emitting layer 772, and a light-emitting layer 773) are provided between the layer 780 and the layer 790 as illustrated in FIG. 41C and FIG. 41D are variations of the single structure. Although FIG. 41C and FIG. 41D illustrate the examples in which three light-emitting layers are included, the light-emitting device with a single structure may include two or four or more light-emitting layers. In addition, the light-emitting device with a single structure may include a buffer layer between two light-emitting layers.

A structure in which a plurality of light-emitting units (a light-emitting unit 763a and a light-emitting unit 763b) are connected in series with a charge-generation layer 785 (also referred to as an intermediate layer) therebetween as illustrated in FIG. 41E and FIG. 41F is referred to as a tandem structure in this specification. Note that a tandem structure may be referred to as a stack structure. The tandem structure enables a light-emitting device to emit light at high luminance. Furthermore, the tandem structure can reduce the amount of current needed for obtaining the same luminance as compared with a single structure, and thus can improve the reliability.

Note that FIG. 41D and FIG. 41F illustrate examples in which the display device includes a layer 764 overlapping with the light-emitting device. FIG. 41D illustrates an example in which the layer 764 overlaps with the light-emitting device illustrated in FIG. 41C, and FIG. 41F illustrates an example in which the layer 764 overlaps with the light-emitting device illustrated in FIG. 41E. In FIG. 41D and FIG. 41F, a conductive film transmitting visible light is used for the upper electrode 762 to extract light to the upper electrode 762 side.

One or both of a color conversion layer and a color filter (a coloring layer) can be used as the layer 764.

In FIG. 41C and FIG. 41D, light-emitting substances emitting light of the same color, or moreover, the same light-emitting substance may be used for the light-emitting layer 771, the light-emitting layer 772, and the light-emitting layer 773. For example, a light-emitting substance emitting blue light may be used for each of the light-emitting layer 771, the light-emitting layer 772, and the light-emitting layer 773. In a subpixel emitting blue light, blue light emitted from the light-emitting device can be extracted. In a subpixel emitting red light and a subpixel emitting green light, by providing a color conversion layer as the layer 764 illustrated in FIG. 41D, blue light emitted from the light-emitting device can be converted into light with a longer wavelength and thus red light or green light can be extracted. As the layer 764, both a color conversion layer and a coloring layer are preferably used. In some cases, part of light emitted from the light-emitting device is transmitted through the color conversion layer without being converted. When light transmitted through the color conversion layer is extracted through the coloring layer, light other than light of the desired color can be absorbed by the coloring layer, and color purity of light emitted from a subpixel can be improved.

In FIG. 41C and FIG. 41D, light-emitting substances emitting light of different colors may be used for the light-emitting layer 771, the light-emitting layer 772, and the light-emitting layer 773. When the light-emitting layer 771, the light-emitting layer 772, and the light-emitting layer 773 emit light of complementary colors, the light emitted from the light-emitting layer 771, the light emitted from the light-emitting layer 772, and the light emitted from the light-emitting layer 773 are mixed and thus white light emission can be obtained as a whole. The light-emitting device with a single structure preferably includes a light-emitting layer containing a light-emitting substance that emits blue light and a light-emitting layer containing a light-emitting substance that emits visible light having a longer wavelength than blue light, for example.

A color filter may be provided as the layer 764 illustrated in FIG. 41D. When white light passes through the color filter, light of a desired color can be obtained.

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

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

The light-emitting device that emits white light preferably contains two or more kinds of light-emitting substances. To obtain white light emission, two or more light-emitting substances may be selected such that their emission colors are complementary colors. For example, when an emission color of a first light-emitting layer and an emission color of a second light-emitting layer are complementary colors, the light-emitting device can be configured to emit white light as a whole. The same applies to a light-emitting device including three or more light-emitting layers.

Also in FIG. 41C and FIG. 41D, the layer 780 and the layer 790 may each independently have a stacked-layer structure of two or more layers as illustrated in FIG. 41B.

In FIG. 41E and FIG. 41F, light-emitting substances emitting light of the same color, or moreover, the same light-emitting substance may be used for the light-emitting layer 771 and the light-emitting layer 772. For example, in light-emitting devices included in subpixels emitting light of different colors, a light-emitting substance that emits blue light may be used for each of the light-emitting layer 771 and the light-emitting layer 772. In the subpixel emitting blue light, blue light emitted from the light-emitting device can be extracted. In the subpixel emitting red light and the subpixel emitting green light, by providing a color conversion layer as the layer 764 illustrated in FIG. 41F, blue light emitted from the light-emitting device can be converted into light with a longer wavelength and thus red light or green light can be extracted. As the layer 764, both a color conversion layer and a coloring layer are preferably used.

In the case where the light-emitting device having the structure illustrated in FIG. 41E or FIG. 41F is used for the subpixels emitting light of different colors, the subpixels may use different light-emitting substances. Specifically, in the light-emitting device included in the subpixel emitting red light, a light-emitting substance that emits red light may be used for each of the light-emitting layer 771 and the light-emitting layer 772. Similarly, in the light-emitting device included in the subpixel emitting green light, a light-emitting substance that emits green light may be used for each of the light-emitting layer 771 and the light-emitting layer 772. In the light-emitting device included in the subpixel emitting blue light, a light-emitting substance that emits blue light may be used for each of the light-emitting layer 771 and the light-emitting layer 772. A display device having such a structure can be regarded as employing a light-emitting device with a tandem structure and an SBS structure. Thus, the display device having such a structure can have both the advantage of a tandem structure and the advantage of an SBS structure. Accordingly, a light-emitting device being capable of high-luminance light emission and having high reliability can be obtained.

In FIG. 41E and FIG. 41F, light-emitting substances emitting light of different colors may be used for the light-emitting layer 771 and the light-emitting layer 772. When the light-emitting layer 771 and the light-emitting layer 772 emit light of complementary colors, the light emitted from the light-emitting layer 771 and the light emitted from the light-emitting layer 772 are mixed and thus white light emission can be obtained as a whole. A color filter may be provided as the layer 764 illustrated in FIG. 41F. When white light passes through the color filter, light of a desired color can be obtained.

Although FIG. 41E and FIG. 41F illustrate examples in which the light-emitting unit 763a includes one light-emitting layer 771 and the light-emitting unit 763b includes one light-emitting layer 772, one embodiment of the present invention is not limited thereto. Each of the light-emitting unit 763a and the light-emitting unit 763b may include two or more light-emitting layers.

Although FIG. 41E and FIG. 41F illustrate the light-emitting device including two light-emitting units, one embodiment of the present invention is not limited thereto. The light-emitting device may include three or more light-emitting units. Note that a structure including two light-emitting units and a structure including three light-emitting units may be referred to as a two-unit tandem structure and a three-unit tandem structure, respectively.

In FIG. 41E and FIG. 41F, the light-emitting unit 763a includes a layer 780a, the light-emitting layer 771, and a layer 790a, and the light-emitting unit 763b includes a layer 780b, the light-emitting layer 772, and a layer 790b.

In the case where the lower electrode 761 is an anode and the upper electrode 762 is a cathode, the layer 780a and the layer 780b each include one or more of a hole-injection layer, a hole-transport layer, and an electron-blocking layer. The layer 790a and the layer 790b each include one or more of an electron-injection layer, an electron-transport layer, and a hole-blocking layer. In the case where the lower electrode 761 is a cathode and the upper electrode 762 is an anode, the structures of the layer 780a and the layer 790a are replaced with each other, and the structures of the layer 780b and the layer 790b are also replaced with each other.

In the case where the lower electrode 761 is an anode and the upper electrode 762 is a cathode, for example, the layer 780a includes a hole-injection layer and a hole-transport layer over the hole-injection layer, and may further include an electron-blocking layer over the hole-transport layer. The layer 790a includes an electron-transport layer, and may further include a hole-blocking layer between the light-emitting layer 771 and the electron-transport layer. The layer 780b includes a hole-transport layer, and may further include an electron-blocking layer over the hole-transport layer. The layer 790b includes an electron-transport layer and an electron-injection layer over the electron-transport layer, and may further include a hole-blocking layer between the light-emitting layer 772 and the electron-transport layer. In the case where the lower electrode 761 is a cathode and the upper electrode 762 is an anode, for example, the layer 780a includes an electron-injection layer and an electron-transport layer over the electron-injection layer, and may further include a hole-blocking layer over the electron-transport layer. The layer 790a includes a hole-transport layer, and may further include an electron-blocking layer between the light-emitting layer 771 and the hole-transport layer. The layer 780b includes an electron-transport layer, and may further include a hole-blocking layer over the electron-transport layer. The layer 790b includes a hole-transport layer and a hole-injection layer over the hole-transport layer, and may further include an electron-blocking layer between the light-emitting layer 772 and the hole-transport layer.

In the case of fabricating a light-emitting device with a tandem structure, two light-emitting units are stacked with the charge-generation layer 785 therebetween. The charge-generation layer 785 includes at least a charge-generation region. The charge-generation layer 785 has a function of injecting electrons into one of the two light-emitting units and injecting holes into the other when voltage is applied between the pair of electrodes.

Structures illustrated in FIG. 42A to FIG. 42C can be given as examples of the light-emitting device with a tandem structure.

FIG. 42A illustrates a structure including three light-emitting units. In FIG. 42A, a plurality of light-emitting units (the light-emitting unit 763a, the light-emitting unit 763b, and a light-emitting unit 763c) are connected in series through the charge-generation layers 785. The light-emitting unit 763a includes the layer 780a, the light-emitting layer 771, and the layer 790a. The light-emitting unit 763b includes the layer 780b, the light-emitting layer 772, and the layer 790b. The light-emitting unit 763c includes a layer 780c, the light-emitting layer 773, and a layer 790c. Note that the layer 780c can have a structure applicable to the layer 780a and the layer 780b, and the layer 790c can have a structure applicable to the layer 790a and the layer 790b.

In FIG. 42A, the light-emitting layer 771, the light-emitting layer 772, and the light-emitting layer 773 preferably contain light-emitting substances that emit light of the same color. Specifically, the light-emitting layer 771, the light-emitting layer 772, and the light-emitting layer 773 can each have a structure containing a red (R) light-emitting substance (what is called a R\R\R three-unit tandem structure); the light-emitting layer 771, the light-emitting layer 772, and the light-emitting layer 773 can each have a structure containing a green (G) light-emitting substance (what is called a G\G\G three-unit tandem structure); or the light-emitting layer 771, the light-emitting layer 772, and the light-emitting layer 773 can each have a structure containing a blue (B) light-emitting substance (what is called a B\B\B three-unit tandem structure). Note that “alb” means that a light-emitting unit containing a light-emitting substance that emits light of b is provided over a light-emitting unit containing a light-emitting substance that emits light of a with a charge-generation layer therebetween, where a and b represent colors.

In FIG. 42A, light-emitting substances emitting light of different colors may be used for some or all of the light-emitting layer 771, the light-emitting layer 772, and the light-emitting layer 773. Examples of a combination of emission colors for the light-emitting layer 771, the light-emitting layer 772, and the light-emitting layer 773 include blue (B) for two of them and yellow (Y) for the other; and red (R) for one of them, green (G) for another, and blue (B) for the other.

Note that the structure containing the light-emitting substances that emit light of the same color is not limited to the above structure. For example, a light-emitting device with a tandem structure may be employed in which light-emitting units each including a plurality of light-emitting layers are stacked as illustrated in FIG. 42B. FIG. 42B illustrates a structure in which two light-emitting units (the light-emitting unit 763a and the light-emitting unit 763b) are connected in series with the charge-generation layer 785 therebetween. The light-emitting unit 763a includes the layer 780a, a light-emitting layer 771a, a light-emitting layer 771b, a light-emitting layer 771c, and the layer 790a. The light-emitting unit 763b includes the layer 780b, a light-emitting layer 772a, a light-emitting layer 772b, a light-emitting layer 772c, and the layer 790b.

In FIG. 42B, the light-emitting unit 763a is configured to emit white (W) light by selecting light-emitting substances for the light-emitting layer 771a, the light-emitting layer 771b, and the light-emitting layer 771c such that their emission colors are complementary colors. Furthermore, the light-emitting unit 763b is configured to emit white (W) light by selecting light-emitting substances for the light-emitting layer 772a, the light-emitting layer 772b, and the light-emitting layer 772c such that their emission colors are complementary colors. That is, the structure illustrated in FIG. 42B is a two-unit tandem structure of WWW. Note that there is no particular limitation on the stacking order of the light-emitting substances satisfying the relationship of complementary colors. The practitioner can select the optimal stacking order as appropriate. Although not illustrated, a three-unit tandem structure of WWWWW or a tandem structure with four or more units may be employed.

In the case where the light-emitting device with a tandem structure is used, the following structure can be used: a BY or Y\B two-unit tandem structure including a light-emitting unit that emits yellow (Y) light and a light-emitting unit that emits blue (B) light; an R·G\B or B\R·G two-unit tandem structure including a light-emitting unit that emits red (R) light and green (G) light and a light-emitting unit that emits blue (B) light; a B\Y\B three-unit tandem structure including a light-emitting unit that emits blue (B) light, a light-emitting unit that emits yellow (Y) light, and a light-emitting unit that emits blue (B) light in this order; a BYG\B three-unit tandem structure including a light-emitting unit that emits blue (B) light, a light-emitting unit that emits yellowish green (YG) light, and a light-emitting unit that emits blue (B) light in this order; and a B\G\B three-unit tandem structure including a light-emitting unit that emits blue (B) light, a light-emitting unit that emits green (G) light, and a light-emitting unit that emits blue (B) light in this order, for example. Note that “a·b” means that one light-emitting unit contains a light-emitting substance that emits light of a and a light-emitting substance that emits light of b.

As illustrated in FIG. 42C, a light-emitting unit including one light-emitting layer and a light-emitting unit including a plurality of light-emitting layers may be used in combination.

Specifically, in the structure illustrated in FIG. 42C, a plurality of light-emitting units (the light-emitting unit 763a, the light-emitting unit 763b, and the light-emitting unit 763c) are connected in series through the charge-generation layers 785. The light-emitting unit 763a includes the layer 780a, the light-emitting layer 771, and the layer 790a. The light-emitting unit 763b includes the layer 780b, the light-emitting layer 772a, the light-emitting layer 772b, the light-emitting layer 772c, and the layer 790b. The light-emitting unit 763c includes the layer 780c, the light-emitting layer 773, and the layer 790c.

As the structure illustrated in FIG. 42C, for example, a three-unit tandem structure of B\R·G·YG\B in which the light-emitting unit 763a is a light-emitting unit that emits blue (B) light, the light-emitting unit 763b is a light-emitting unit that emits red (R), green (G), and yellowish green (YG) light, and the light-emitting unit 763c is a light-emitting unit that emits blue (B) light can be employed.

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

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

A conductive film transmitting visible light is used for the electrode through which light is extracted, which is either the lower electrode 761 or the upper electrode 762. A conductive film reflecting visible light is preferably used for the electrode through which light is not extracted. In the case where a display device includes a light-emitting device emitting infrared light, it is preferable that a conductive film transmitting visible light and infrared light be used for the electrode through which light is extracted and that a conductive film reflecting visible light and infrared light be used for the electrode through which light is not extracted.

A conductive film transmitting visible light may be used also for the electrode through which light is not extracted. In that case, the conductive film is preferably provided between a reflective layer and the EL layer 763. In other words, light emitted from the EL layer 763 may be reflected by the reflective layer to be extracted from the display device.

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

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

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

The transparent electrode has a light transmittance higher than or equal to 40%. For example, an electrode having a visible light (light with a wavelength longer than or equal to 400 nm and shorter than 750 nm) transmittance higher than or equal to 40% is preferably used as the transparent electrode of the light-emitting device. The visible light reflectance of the transflective electrode is higher than or equal to 10% and lower than or equal to 95%, preferably higher than or equal to 30% and lower than or equal to 80%. The visible light reflectance of the reflective electrode is higher than or equal to 40% and lower than or equal to 100%, preferably higher than or equal to 70% and lower than or equal to 100%. These electrodes preferably have a resistivity of 1×10⁻² Ωcm or lower.

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

Either a low molecular compound or a high molecular compound can be used for the light-emitting device, and an inorganic compound may also be included. Each layer included in the light-emitting device can be formed by a method such as an evaporation method (including a vacuum evaporation method), a transfer method, a printing method, an inkjet method, or a coating method.

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

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

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

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

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

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

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

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

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

As the material with a high hole-injection property, a material that contains a hole-transport material and the above-described oxide of a metal belonging to any of Group 4 to Group 8 of the periodic table (typically, molybdenum oxide) may be used, for example.

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

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

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

The electron-transport layer is a layer transporting electrons, which are injected from the cathode by the electron-injection layer, to the light-emitting layer. The electron-transport layer is a layer that contains an electron-transport material. As the electron-transport material, a substance having an electron mobility greater than or equal to 1×10⁻⁶ cm²/Vs is preferable. Note that other substances can also be used as long as they have a property of transporting more electrons than holes. As the electron-transport material, it is possible to use a material with a high electron-transport property, such as a metal complex having a quinoline skeleton, a metal complex having a benzoquinoline skeleton, a metal complex having an oxazole skeleton, a metal complex having a thiazole skeleton, an oxadiazole derivative, a triazole derivative, an imidazole derivative, an oxazole derivative, a thiazole derivative, a phenanthroline derivative, a quinoline derivative having a quinoline ligand, a benzoquinoline derivative, a quinoxaline derivative, a dibenzoquinoxaline derivative, a pyridine derivative, a bipyridine derivative, a pyrimidine derivative, or a x-electron deficient heteroaromatic compound including a nitrogen-containing heteroaromatic compound.

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

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

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

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

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

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

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

For example, 4,7-diphenyl-1,10-phenanthroline (abbreviation: BPhen), 2,9-di(naphthalen-2-yl)-4,7-diphenyl-1,10-phenanthroline (abbreviation: NBPhen), 2,2′-(1,3-phenylene)bis[9-phenyl-1,10-phenanthroline] (abbreviation: mPPhen2P), diquinoxalino[2,3-a: 2′,3′-c] phenazine (abbreviation: HATNA), 2,4,6-tris[3′-(pyridin-3-yl)biphenyl-3-yl]-1,3,5-triazine (abbreviation: TmPPPyTz), or the like can be used as the organic compound having an unshared electron pair. Note that NBPhen has a higher glass transition point (Tg) than BPhen and thus has high heat resistance.

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

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

The electron-injection buffer layer preferably contains an alkali metal or an alkaline earth metal, and for example, can be configured to contain an alkali metal compound or an alkaline earth metal compound. Specifically, the electron-injection buffer layer preferably contains an inorganic compound containing an alkali metal and oxygen or an inorganic compound containing an alkaline earth metal and oxygen, further preferably contains an inorganic compound containing lithium and oxygen (e.g., lithium oxide (LizO)). In addition, a material that can be used for the aforementioned electron-injection layer can be suitably used for the electron-injection buffer layer.

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

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

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

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

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

This embodiment can be combined with any of the other embodiments as appropriate.

Embodiment 6

In this embodiment, a light-receiving device that can be used for the display device of one embodiment of the present invention and a display device having a light detection function will be described.

[Light-Receiving Device]

As illustrated in FIG. 43A, the light-receiving device includes a layer 765 between a pair of electrodes (the lower electrode 761 and the upper electrode 762). The layer 765 includes at least one active layer, and may further include another layer.

FIG. 43B is a variation example of the layer 765 included in the light-receiving device illustrated in FIG. 43A. Specifically, the light-receiving device illustrated in FIG. 43B includes a layer 766 over the lower electrode 761, an active layer 767 over the layer 766, a layer 768 over the active layer 767, and the upper electrode 762 over the layer 768.

The active layer 767 functions as a photoelectric conversion layer.

In the case where the lower electrode 761 is an anode and the upper electrode 762 is a cathode, the layer 766 includes one or both of a hole-transport layer and an electron-blocking layer. The layer 768 includes one or both of an electron-transport layer and a hole-blocking layer. In the case where the lower electrode 761 is a cathode and the upper electrode 762 is an anode, the structures of the layer 766 and the layer 768 are replaced with each other.

Next, materials that can be used for the light-receiving device will be described.

Either a low molecular compound or a high molecular compound can be used for the light-receiving device, and an inorganic compound may also be included. Each layer included in the light-receiving device can be formed by a method such as an evaporation method (including a vacuum evaporation method), a transfer method, a printing method, an inkjet method, or a coating method.

The active layer included in the light-receiving device includes a semiconductor.

Examples of the semiconductor include an inorganic semiconductor such as silicon and an organic semiconductor including an organic compound. This embodiment describes an example in which an organic semiconductor is used as the semiconductor included in the active layer. The use of an organic semiconductor is preferable because the light-emitting layer and the active layer can be formed by the same method (e.g., a vacuum evaporation method) and thus the same manufacturing apparatus can be used.

Examples of an n-type semiconductor material included in the active layer include electron-accepting organic semiconductor materials such as fullerene (e.g., C₆₀ and C₇₀) and fullerene derivatives. Examples of the fullerene derivative include[6,6]-Phenyl-C71-butyric acid methyl ester (abbreviation: PC70BM), [6,6]-Phenyl-C61-butyric acid methyl ester (abbreviation: PC60BM), and 1′, 1″, 4′, 4″-Tetrahydro-di[1,4] methanonaphthaleno[1,2:2′, 3′, 56,60:2″, 3″][5,6] fullerene-C60 (abbreviation: ICBA).

Other examples of an n-type semiconductor material include perylenetetracarboxylic acid derivatives such as N,N′-dimethyl-3,4,9,10-perylenetetracarboxylic diimide (abbreviation: Me-PTCDI) and 2,2′-(5,5′-(thieno[3,2-b] thiophene-2,5-diyl)bis(thiophene-5,2-diyl))bis(methan-1-yl-1-ylidene)dimalononitrile (abbreviation: FT2TDMN).

Other examples of an n-type semiconductor material include a metal complex having a quinoline skeleton, a metal complex having a benzoquinoline skeleton, a metal complex having an oxazole skeleton, a metal complex having a thiazole skeleton, an oxadiazole derivative, a triazole derivative, an imidazole derivative, an oxazole derivative, a thiazole derivative, a phenanthroline derivative, a quinoline derivative, a benzoquinoline derivative, a quinoxaline derivative, a dibenzoquinoxaline derivative, a pyridine derivative, a bipyridine derivative, a pyrimidine derivative, a naphthalene derivative, an anthracene derivative, a coumarin derivative, a rhodamine derivative, a triazine derivative, and a quinone derivative.

Examples of a p-type semiconductor material included in the active layer include electron-donating organic semiconductor materials such as copper (II) phthalocyanine (CuPc), tetraphenyldibenzoperiflanthene (DBP), zinc phthalocyanine (ZnPc), tin phthalocyanine (SnPc), quinacridone, and rubrene.

Other examples of a p-type semiconductor material include a carbazole derivative, a thiophene derivative, a furan derivative, and a compound having an aromatic amine skeleton. Other examples of a p-type semiconductor material include a naphthalene derivative, an anthracene derivative, a pyrene derivative, a triphenylene derivative, a fluorene derivative, a pyrrole derivative, a benzofuran derivative, a benzothiophene derivative, an indole derivative, a dibenzofuran derivative, a dibenzothiophene derivative, an indolocarbazole derivative, a porphyrin derivative, a phthalocyanine derivative, a naphthalocyanine derivative, a quinacridone derivative, a rubrene derivative, a tetracene derivative, a polyphenylene vinylene derivative, a polyparaphenylene derivative, a polyfluorene derivative, a polyvinylcarbazole derivative, and a polythiophene derivative.

The HOMO level of the electron-donating organic semiconductor material is preferably shallower (higher) than the HOMO level of the electron-accepting organic semiconductor material. The LUMO level of the electron-donating organic semiconductor material is preferably shallower (higher) than the LUMO level of the electron-accepting organic semiconductor material.

Fullerene having a spherical shape is preferably used as the electron-accepting organic semiconductor material, and an organic semiconductor material having a substantially planar shape is preferably used as the electron-donating organic semiconductor material. Molecules of similar shapes tend to aggregate, and aggregated molecules of similar kinds, which have molecular orbital energy levels close to each other, can increase the carrier-transport property.

For the active layer, a high molecular compound such as Poly[[4,8-bis[5-(2-ethylhexyl)-2-thienyl]benzo[1,2-b: 4,5-b′]dithiophene-2,6-diyl]-2,5-thiophenediyl[5,7-bis(2-ethylhexyl)-4,8-dioxo-4H,8H-benzo[1,2-c: 4,5-c′] dithiophene-1,3-diyl]] polymer (abbreviation: PBDB-T) or a PBDB-T derivative, which functions as a donor, can be used. For example, a method in which an acceptor material is dispersed to PBDB-T or a PBDB-T derivative can be used.

For example, the active layer is preferably formed by co-evaporation of an n-type semiconductor and a p-type semiconductor. Alternatively, the active layer may be formed by stacking an n-type semiconductor and a p-type semiconductor.

Three or more kinds of materials may be mixed for the active layer. For example, a third material may be mixed with an n-type semiconductor material and a p-type semiconductor material in order to extend the wavelength range of the light to be detected. The third material here may be a low molecular compound or a high molecular compound.

In addition to the active layer, the light-receiving device may further include a layer containing a substance with a high hole-transport property, a substance with a high electron-transport property, a substance with a bipolar property (a substance with a high electron-transport property and a high hole-transport property), or the like. Without limitation to the above, the light-receiving device may further include a layer containing a substance with a high hole-injection property, a hole-blocking material, a substance with a high electron-injection property, an electron-blocking material, or the like. Layers other than the active layer included in the light-receiving device can be formed using a material that can be used for the light-emitting device described above, for example.

As the hole-transport material or the electron-blocking material, a high molecular compound such as poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonic acid) (PEDOT/PSS), or an inorganic compound such as molybdenum oxide or copper iodide (Cul) can be used, for example. As the electron-transport material or the hole-blocking material, an inorganic compound such as zinc oxide (ZnO), or an organic compound such as polyethylenimine ethoxylate (PEIE) can be used. The light-receiving device may include a mixed film of PEIE and ZnO, for example.

[Display Device Having Light Detection Function]

In the display device of one embodiment of the present invention, the light-emitting devices are arranged in a matrix in a display portion, and an image can be displayed on the display portion. Furthermore, the light-receiving devices are arranged in a matrix in the display portion, and the display portion has one or both of an image capturing function and a sensing function in addition to an image displaying function. The display portion can be used as an image sensor or a touch sensor. That is, by detecting light with the display portion, an image can be captured or the approach or contact of an object (e.g., a finger, a hand, or a pen) can be detected.

Furthermore, in the display device of one embodiment of the present invention, the light-emitting devices can be used as a light source of the sensor. In the display device of one embodiment of the present invention, when an object reflects (or scatters) light emitted from the light-emitting device included in the display portion, the light-receiving device can detect reflected light (or scattered light); thus, image capturing or touch detection is possible even in a dark place.

Accordingly, a light-receiving portion and a light source do not need to be provided separately from the display device; hence, the number of components of an electronic device can be reduced. For example, a biometric authentication device, a capacitive touch panel for scroll operation, or the like is not necessarily provided separately from the electronic device. Thus, with the use of the display device of one embodiment of the present invention, the electronic device can be provided with reduced manufacturing cost.

Specifically, the display device of one embodiment of the present invention includes a light-emitting device and a light-receiving device in a pixel. In the display device of one embodiment of the present invention, an organic EL device is used as the light-emitting device, and an organic photodiode is used as the light-receiving device. The organic EL device and the organic photodiode can be formed over the same substrate. Thus, the organic photodiode can be incorporated in the display device using the organic EL device.

In the display device including the light-emitting device and the light-receiving device in the pixel, the pixel has a light-receiving function; thus, the display device can detect a contact or approach of an object while displaying an image. For example, all the subpixels included in the display device can display an image; alternatively, some of the subpixels can emit light as a light source and the other subpixels can display an image.

In the case where the light-receiving device is used as an image sensor, the display device can capture an image with the use of the light-receiving device. For example, the display device of this embodiment can be used as a scanner.

For example, image capturing for personal authentication with the use of a fingerprint, a palm print, the iris, the shape of a blood vessel (including the shape of a vein and the shape of an artery), a face, or the like can be performed using the image sensor.

For example, an image of the periphery, surface, or inside (e.g., fundus) of an eye of a user of a wearable device can be captured using the image sensor. Therefore, the wearable device can have a function of detecting one or more selected from blinking, movement of an iris, and movement of an eyelid of the user.

The light-receiving device can be used for a touch sensor (also referred to as a direct touch sensor), a near touch sensor (also referred to as a hover sensor, a hover touch sensor, a contactless sensor, or a touchless sensor), or the like.

Here, the touch sensor or the near touch sensor can detect the approach or contact of an object (e.g., a finger, a hand, or a pen).

The touch sensor can detect an object when the display device and the object come in direct contact with each other. The near touch sensor can detect an object even when the object is not in contact with the display device. For example, the display device is preferably capable of detecting an object when the distance between the display device and the object is greater than or equal to 0.1 mm and less than or equal to 300 mm, preferably greater than or equal to 3 mm and less than or equal to 50 mm. With this structure, the display device can be operated without direct contact of an object. In other words, the display device can be operated in a contactless (touchless) manner. With the above structure, the display device can have a reduced risk of being dirty or damaged, or can be operated without the object directly touching a dirt (e.g., dust or a virus) attached to the display device.

The refresh rate can be variable in the display device of one embodiment of the present invention. For example, the refresh rate is adjusted (adjusted in the range from 1 Hz to 240 Hz, for example) in accordance with the content displayed on the display device, whereby power consumption can be reduced. The driving frequency of the touch sensor or the near touch sensor may be changed in accordance with the refresh rate. For example, when the refresh rate of the display device is 120 Hz, the driving frequency of the touch sensor or the near touch sensor can be higher than 120 Hz (can typically be 240 Hz). With this structure, low power consumption can be achieved, and the response speed of the touch sensor or the near touch sensor can be increased.

The display device 100 illustrated in FIG. 43C to FIG. 43E includes a layer 353 including a light-receiving device, a functional layer 355, and a layer 357 including a light-emitting device, between a substrate 351 and a substrate 359.

The functional layer 355 includes a circuit for driving a light-receiving device and a circuit for driving a light-emitting device. One or more of a switch, a transistor, a capacitor, a resistor, a wiring, a terminal, and the like can be provided in the functional layer 355. Note that in the case where the light-emitting device and the light-receiving device are driven by a passive-matrix method, a structure including neither a switch nor a transistor may be employed.

For example, after light emitted from the light-emitting device in the layer 357 including the light-emitting device is reflected by a finger 352 in contact with the display device 100 as illustrated in FIG. 43C, the light-receiving device in the layer 353 including the light-receiving device detects the reflected light. Thus, the contact of the finger 352 with the display device 100 can be detected.

The display device may have a function of detecting an object that is approaching (not in contact with) the display device as illustrated in FIG. 43D and FIG. 43E or capturing an image of such an object. FIG. 43C and FIG. 43D illustrate an example in which a human finger is detected, and FIG. 43E illustrates an example in which information on the periphery, surface, or inside of the human eye (e.g., the number of blinks, movement of an eyeball, and movement of an eyelid) is detected.

This embodiment can be combined with any of the other embodiments as appropriate.

Embodiment 7

In this embodiment, electronic devices of one embodiment of the present invention will be described with reference to FIG. 44 to FIG. 46.

Electronic devices of this embodiment are each provided with the display device of one embodiment of the present invention in a display portion. The display device of one embodiment of the present invention can be easily increased in resolution and definition. Thus, the display device of one embodiment of the present invention can be used for display portions of a variety of electronic devices.

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

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

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

The electronic device of this embodiment may include a sensor (a sensor having a function of sensing, detecting, or measuring force, displacement, position, speed, acceleration, angular velocity, rotational frequency, distance, light, liquid, magnetism, temperature, a chemical substance, sound, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, gradient, oscillation, a smell, or infrared rays).

The electronic device of this embodiment can have a variety of functions. For example, the electronic device can have a function of displaying a variety of information (a still image, a moving image, a text image, and the like) on the display portion, a touch panel function, a function of displaying a calendar, date, time, and the like, a function of executing a variety of software (programs), a wireless communication function, and a function of reading out a program or data stored in a recording medium.

Examples of a wearable device that can be worn on a head are described with reference to FIG. 44A to FIG. 44D. These wearable devices have at least one of a function of displaying AR content, a function of displaying VR content, a function of displaying SR content, and a function of displaying MR content. The electronic device having a function of displaying the content of at least one of AR, VR, SR, MR, and the like enables a user to feel a higher sense of immersion.

An electronic device 700A illustrated in FIG. 44A and an electronic device 700B illustrated in FIG. 44B each include a pair of display panels 751, a pair of housings 721, a communication portion (not illustrated), a pair of wearing portions 723, a control portion (not illustrated), an image capturing portion (not illustrated), a pair of optical members 753, a frame 757, and a pair of nose pads 758.

The display device of one embodiment of the present invention can be used for the display panels 751. Thus, the electronic device can perform display with extremely high resolution.

The electronic device 700A and the electronic device 700B can each project images displayed on the display panels 751 onto display regions 756 of the optical members 753. Since the optical members 753 have a light-transmitting property, a user can see images displayed on the display regions, which are superimposed on transmission images seen through the optical members 753. Accordingly, the electronic device 700A and the electronic device 700B are electronic devices capable of AR display.

In each of the electronic device 700A and the electronic device 700B, a camera capable of capturing images of the front side may be provided as the image capturing portion. Furthermore, when the electronic device 700A and the electronic device 700B are each provided with an acceleration sensor such as a gyroscope sensor, the orientation of the user's head can be sensed and an image corresponding to the orientation can be displayed on the display regions 756.

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

The electronic device 700A and the electronic device 700B are each provided with a battery so that they can be charged wirelessly and/or by wire.

A touch sensor module may be provided in the housing 721. The touch sensor module has a function of detecting touch on the outer surface of the housing 721. A tap operation or a slide operation, for example, by the user can be detected with the touch sensor module, so that a variety of processing can be executed. For example, processing such as a pause or a restart of a moving image can be executed by a tap operation, and processing such as fast forward and fast rewind can be executed by a slide operation. When the touch sensor module is provided in each of the two housings 721, the range of the operation can be increased.

A variety of touch sensors can be used for the touch sensor module. For example, any of touch sensors of various types such as a capacitive type, a resistive type, an infrared type, an electromagnetic induction type, a surface acoustic wave type, and an optical type can be employed. In particular, a capacitive sensor or an optical sensor is preferably used for the touch sensor module.

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

An electronic device 800A illustrated in FIG. 44C and an electronic device 800B illustrated in FIG. 44D each include a pair of display portions 820, a housing 821, a communication portion 822, a pair of wearing portions 823, a control portion 824, a pair of image capturing portions 825, and a pair of lenses 832.

The display device of one embodiment of the present invention can be used for the display portions 820. Thus, the electronic device can perform display with extremely high resolution. This enables a user to feel a high sense of immersion.

The display portions 820 are provided at a position inside the housing 821 so as to be seen through the lenses 832. When the pair of display portions 820 display different images, three-dimensional display using parallax can be performed.

The electronic device 800A and the electronic device 800B can be regarded as electronic devices for VR. The user who wears the electronic device 800A or the electronic device 800B can see images displayed on the display portions 820 through the lenses 832.

The electronic device 800A and the electronic device 800B each preferably include a mechanism for adjusting the lateral positions of the lenses 832 and the display portions 820 so that the lenses 832 and the display portions 820 are positioned optimally in accordance with the positions of the user's eyes. Moreover, the electronic device 800A and the electronic device 800B each preferably include a mechanism for adjusting focus by changing the distance between the lenses 832 and the display portions 820.

The electronic device 800A or the electronic device 800B can be worn on the user's head with the wearing portions 823. FIG. 44C and the like illustrate examples in which the wearing portion 823 has a shape like a temple (also referred to as a joint or the like) of glasses; however, one embodiment of the present invention is not limited thereto. The wearing portion 823 can have any shape with which the user can wear the electronic device, for example, a shape of a helmet or a band.

The image capturing portion 825 has a function of obtaining information on the external environment. Data obtained by the image capturing portion 825 can be output to the display portion 820. An image sensor can be used for the image capturing portion 825. Moreover, a plurality of cameras may be provided so as to cover a plurality of fields of view, such as a telescope field of view and a wide field of view.

Although an example of including the image capturing portion 825 is described here, a range sensor (hereinafter, also referred to as a sensing portion) that is capable of measuring a distance from an object may be provided. That is, the image capturing portion 825 is one embodiment of the sensing portion. As the sensing portion, an image sensor or a distance image sensor such as LIDAR (Light Detection And Ranging) can be used, for example. With the use of images obtained by the camera and images obtained by the distance image sensor, more pieces of information can be obtained and a gesture operation with higher accuracy is possible.

The electronic device 800A may include a vibration mechanism that functions as bone-conduction earphones. For example, a structure including the vibration mechanism can be employed for any one or more of the display portion 820, the housing 821, and the wearing portion 823. Thus, without additionally requiring an audio device such as headphones, earphones, or a speaker, the user can enjoy a video and sound only by wearing the electronic device 800A.

The electronic device 800A and the electronic device 800B may each include an input terminal. To the input terminal, a cable for supplying a video signal from a video output device or the like, power for charging a battery provided in the electronic device, and the like can be connected.

The electronic device of one embodiment of the present invention may have a function of performing wireless communication with earphones 750. The earphones 750 include a communication portion (not illustrated) and have a wireless communication function. The earphones 750 can receive information (e.g., audio data) from the electronic device with the wireless communication function. For example, the electronic device 700A illustrated in FIG. 44A has a function of transmitting information to the earphones 750 with the wireless communication function. For another example, the electronic device 800A illustrated in FIG. 44C has a function of transmitting information to the earphones 750 with the wireless communication function.

The electronic device may include an earphone portion. The electronic device 700B illustrated in FIG. 44B includes earphone portions 727. For example, the earphone portion 727 and the control portion can be connected to each other by wire. Part of a wiring that connects the earphone portion 727 and the control portion may be positioned inside the housing 721 or the wearing portion 723.

Similarly, the electronic device 800B illustrated in FIG. 44D includes earphone portions 827. For example, the earphone portion 827 and the control portion 824 can be connected to each other by wire. Part of a wiring that connects the earphone portion 827 and the control portion 824 may be positioned inside the housing 821 or the wearing portion 823. The earphone portions 827 and the wearing portions 823 may include magnets. This is preferable because the earphone portions 827 can be fixed to the wearing portions 823 with magnetic force and thus can be easily housed.

The electronic device may include an audio output terminal to which earphones, headphones, or the like can be connected. The electronic device may include one or both of an audio input terminal and an audio input mechanism. As the audio input mechanism, a sound collecting device such as a microphone can be used, for example. The electronic device may have a function of what is called a headset by including the audio input mechanism.

As described above, both the glasses-type device (e.g., the electronic device 700A and the electronic device 700B) and the goggles-type device (e.g., the electronic device 800A and the electronic device 800B) are suitable as the electronic device of one embodiment of the present invention.

The electronic device of one embodiment of the present invention can transmit information to earphones by wire or wirelessly.

An electronic device 6500 illustrated in FIG. 45A is a portable information terminal that can be used as a smartphone.

The electronic device 6500 includes a housing 6501, a display portion 6502, a power button 6503, buttons 6504, a speaker 6505, a microphone 6506, a camera 6507, a light source 6508, and the like. The display portion 6502 has a touch panel function.

The display device of one embodiment of the present invention can be used for the display portion 6502.

FIG. 45B is a schematic cross-sectional view including an end portion of the housing 6501 on the microphone 6506 side.

A protection member 6510 having a light-transmitting property is provided on a display surface side of the housing 6501, and a display panel 6511, an optical member 6512, a touch sensor panel 6513, a printed circuit board 6517, a battery 6518, and the like are placed in a space surrounded by the housing 6501 and the protection member 6510.

The display panel 6511, the optical member 6512, and the touch sensor panel 6513 are fixed to the protection member 6510 with an adhesive layer (not illustrated).

Part of the display panel 6511 is folded back in a region outside the display portion 6502, and an FPC 6515 is connected to the part that is folded back. An IC 6516 is mounted on the FPC 6515. The FPC 6515 is connected to a terminal provided on the printed circuit board 6517.

A flexible display device of one embodiment of the present invention can be used for the display panel 6511. Thus, an extremely lightweight electronic device can be obtained. Since the display panel 6511 is extremely thin, the battery 6518 with high capacity can be mounted while an increase in thickness of the electronic device is suppressed. Moreover, part of the display panel 6511 is folded back such that a connection portion with the FPC 6515 is provided on the back side of the display portion 6502, whereby an electronic device with a narrow bezel can be obtained.

FIG. 45C illustrates an example of a television device. In a television device 7100, a display portion 7000 is incorporated in a housing 7101. Here, the housing 7101 is supported by a stand 7103.

The display device of one embodiment of the present invention can be used for the display portion 7000.

Operation of the television device 7100 illustrated in FIG. 45C can be performed with an operation switch provided in the housing 7101 and a separate remote control 7111. Alternatively, the display portion 7000 may include a touch sensor, and the television device 7100 may be operated by touch on the display portion 7000 with a finger or the like. The remote control 7111 may be provided with a display portion for displaying information output from the remote control 7111. With operation keys or a touch panel provided in the remote control 7111, channels and volume can be operated and videos displayed on the display portion 7000 can be operated.

Note that the television device 7100 has a structure in which a receiver, a modem, and the like are provided. A general television broadcast can be received with the receiver. When the television device is connected to a communication network with or without wires via the modem, one-way (from a transmitter to a receiver) or two-way (between a transmitter and a receiver or between receivers, for example) information communication can be performed.

FIG. 45D illustrates an example of a laptop personal computer. A laptop personal computer 7200 includes a housing 7211, a keyboard 7212, a pointing device 7213, an external connection port 7214, and the like. In the housing 7211, the display portion 7000 is incorporated.

The display device of one embodiment of the present invention can be used for the display portion 7000.

FIG. 45E and FIG. 45F illustrate examples of digital signage.

Digital signage 7300 illustrated in FIG. 45E includes a housing 7301, the display portion 7000, a speaker 7303, and the like. The digital signage 7300 can also include an LED lamp, an operation key (including a power switch or an operation switch), a connection terminal, a variety of sensors, a microphone, and the like.

FIG. 45F is digital signage 7400 attached to a cylindrical pillar 7401. The digital signage 7400 includes the display portion 7000 provided along a curved surface of the pillar 7401.

The display device of one embodiment of the present invention can be used for the display portion 7000 in FIG. 45E and FIG. 45F.

A larger area of the display portion 7000 can increase the amount of information that can be provided at a time. The larger display portion 7000 attracts more attention, so that the effectiveness of the advertisement can be increased, for example.

The use of a touch panel in the display portion 7000 is preferable because in addition to display of a still image or a moving image on the display portion 7000, intuitive operation by a user is possible. Moreover, for an application for providing information such as route information or traffic information, usability can be enhanced by intuitive operation.

As illustrated in FIG. 45E and FIG. 45F, it is preferable that the digital signage 7300 or the digital signage 7400 be capable of working with an information terminal 7311 or an information terminal 7411 such as a smartphone a user has through wireless communication. For example, information of an advertisement displayed on the display portion 7000 can be displayed on a screen of the information terminal 7311 or the information terminal 7411. By operation of the information terminal 7311 or the information terminal 7411, display on the display portion 7000 can be switched.

It is possible to make the digital signage 7300 or the digital signage 7400 execute a game with use of the screen of the information terminal 7311 or the information terminal 7411 as an operation means (controller). Thus, an unspecified number of users can join in and enjoy the game concurrently.

Electronic devices illustrated in FIG. 46A to FIG. 46G each include a housing 9000, a display portion 9001, a speaker 9003, an operation key 9005 (including a power switch or an operation switch), a connection terminal 9006, a sensor 9007 (a sensor having a function of sensing, detecting, or measuring force, displacement, position, speed, acceleration, angular velocity, rotational frequency, distance, light, liquid, magnetism, temperature, a chemical substance, sound, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, gradient, oscillation, a smell, or infrared rays), a microphone 9008, and the like.

The display device of one embodiment of the present invention can be used for the display portion 9001 in FIG. 46A to FIG. 46G.

The electronic devices illustrated in FIG. 46A to FIG. 46G have a variety of functions. For example, the electronic devices can have a function of displaying a variety of information (a still image, a moving image, a text image, and the like) on the display portion, a touch panel function, a function of displaying a calendar, date, time, and the like, a function of controlling processing with the use of a variety of software (programs), a wireless communication function, and a function of reading out and processing a program or data stored in a recording medium. Note that the functions of the electronic devices are not limited thereto, and the electronic devices can have a variety of functions. The electronic devices may each include a plurality of display portions. The electronic devices may each be provided with a camera or the like and have a function of taking a still image or a moving image and storing the taken image in a recording medium (an external recording medium or a recording medium incorporated in the camera), a function of displaying the taken image on the display portion, or the like.

The electronic devices illustrated in FIG. 46A to FIG. 46G are described in detail below.

FIG. 46A is a perspective view illustrating a portable information terminal 9101. For example, the portable information terminal 9101 can be used as a smartphone. Note that the portable information terminal 9101 may be provided with the speaker 9003, the connection terminal 9006, the sensor 9007, or the like. The portable information terminal 9101 can display characters and image information on its plurality of surfaces. FIG. 46A illustrates an example in which three icons 9050 are displayed. Furthermore, information 9051 indicated by dashed rectangles can be displayed on another surface of the display portion 9001. Examples of the information 9051 include notification of reception of an e-mail, an SNS message, or an incoming call, the title and sender of an e-mail, an SNS message, or the like, the date, the time, remaining battery, and the radio field intensity. Alternatively, the icon 9050 or the like may be displayed at the position where the information 9051 is displayed.

FIG. 46B is a perspective view illustrating a portable information terminal 9102. The portable information terminal 9102 has a function of displaying information on three or more surfaces of the display portion 9001. Illustrated here is an example in which information 9052, information 9053, and information 9054 are displayed on different surfaces. For example, a user can check the information 9053 displayed such that it can be seen from above the portable information terminal 9102, with the portable information terminal 9102 put in a breast pocket of his/her clothes. The user can see the display without taking out the portable information terminal 9102 from the pocket and decide whether to answer the call, for example.

FIG. 46C is a perspective view illustrating a tablet terminal 9103. The tablet terminal 9103 is capable of executing a variety of applications such as mobile phone calls, e-mailing, viewing and editing texts, music reproduction, Internet communication, and a computer game. The tablet terminal 9103 includes the display portion 9001, a camera 9002, the microphone 9008, and the speaker 9003 on the front surface of the housing 9000; the operation keys 9005 as buttons for operation on the left side surface of the housing 9000; and the connection terminal 9006 on the bottom surface of the housing 9000.

FIG. 46D is a perspective view illustrating a watch-type portable information terminal 9200. For example, the portable information terminal 9200 can be used as a Smartwatch (registered trademark). The display surface of the display portion 9001 is curved, and an image can be displayed on the curved display surface. Furthermore, mutual communication between the portable information terminal 9200 and, for example, a headset capable of wireless communication enables hands-free calling. With the connection terminal 9006, the portable information terminal 9200 can perform mutual data transmission with another information terminal and charging. Note that the charging operation may be performed by wireless power feeding.

FIG. 46E to FIG. 46G are perspective views illustrating a foldable portable information terminal 9201. FIG. 46E is a perspective view of an opened state of the portable information terminal 9201, FIG. 46G is a perspective view of a folded state thereof, and FIG. 46F is a perspective view of a state in the middle of change from one of FIG. 46E and FIG. 46G to the other. The portable information terminal 9201 is highly portable in the folded state and is highly browsable in the opened state because of a seamless large display region. The display portion 9001 of the portable information terminal 9201 is supported by three housings 9000 joined together by hinges 9055. The display portion 9001 can be folded with a radius of curvature greater than or equal to 0.1 mm and less than or equal to 150 mm, for example.

This embodiment can be combined with any of the other embodiments as appropriate.

REFERENCE NUMERALS

11B: subpixel, 11G: subpixel, 11R: subpixel, 11S: subpixel, 100A: display device, 100B: display device, 100C: display device, 100D: display device, 100E: display device, 100F: display device, 100G: display device, 100H: display device, 100I: display device, 100: display device, 101: layer, 107B_1: sidewall insulating layer, 107B_2: sidewall insulating layer, 107B_3: sidewall insulating layer, 107b: sidewall insulating film, 107C_1: material layer, 107C_2: material layer, 107C_3: material layer, 107G_1: sidewall insulating layer, 107G_2: sidewall insulating layer, 107g: sidewall insulating film, 107R_1: sidewall insulating layer, 107r: sidewall insulating film, 107S_1: sidewall insulating layer, 107S_2: sidewall insulating layer, 107S_3: sidewall insulating layer, 107: sidewall insulating layer, 110a: subpixel, 110b: subpixel, 110c: subpixel pixel, 110d: subpixel, 110e: subpixel, 110: pixel, 111B: conductive layer, 111b: conductive film, 111G: conductive layer, 111g: conductive film, 111R: conductive layer, 111r: conductive film, 111S: conductive layer, 111: conductive layer, 112B: conductive layer, 112G: conductive layer, 112R: conductive layer, 112S: conductive layer, 113B: layer, 113b: film, 113G: layer, 113g: film, 113R: layer, 113r: film, 113S: layer, 114: common layer, 115: common electrode, 116B: conductive layer, 116G: conductive layer, 116R: conductive layer, 116: conductive layer, 117: light-blocking layer, 118B: mask layer, 118b: mask film, 118G: mask layer, 118g: mask film, 118R: mask layer, 118r: mask film, 118S: mask layer, 118: mask layer, 119B: mask layer, 119b: mask film, 119G: mask layer, 119g: mask film, 119R: mask layer, 119r: mask film, 120: substrate, 121a: plasma, 121b: plasma, 121c: plasma, 122: resin layer, 123: conductive layer, 124a: pixel, 124b: pixel, 125A: insulating film, 125: insulating layer, 126B: conductive layer, 126G: conductive layer, 126R: conductive layer, 126S: conductive layer, 127a: insulating film, 127b: insulating layer, 127: insulating layer, 128: layer, 129B: conductive layer, 129G: conductive layer, 129R: conductive layer, 129S: conductive layer, 130B: light-emitting device, 130G: light-emitting device, 130R: light-emitting device, 131: protective layer, 132B: coloring layer, 132G: coloring layer, 132R: coloring layer, 133: lens, 134: insulating layer, 136a: mask, 136b: mask, 136: mask, 139: light, 140: connection portion, 142: adhesive layer, 150: light-receiving device, 151: substrate, 152: substrate, 153: insulating layer, 162: display portion, 164: circuit, 165: wiring, 166: conductive layer, 172: FPC, 173: IC, 190B: resist mask, 190G: resist mask, 190R: resist mask, 201: transistor, 204: connection portion, 205: transistor, 209: transistor, 210: transistor, 211: insulating layer, 213: insulating layer, 214: insulating layer, 215: insulating layer, 218: insulating layer, 221: conductive layer, 222a: conductive layer, 222b: conductive layer, 223: conductive layer, 225: insulating layer, 231i: channel formation region, 231n: low-resistance region, 231: semiconductor layer, 240: capacitor, 241: conductive layer, 242: connection layer, 243: insulating layer, 245: conductive layer, 251: conductive layer, 252: conductive layer, 254: insulating layer, 255a: insulating layer, 255b: insulating layer, 255c: insulating layer, 256: plug, 261: insulating layer, 262: insulating layer, 263: insulating layer, 264: insulating layer, 265: insulating layer, 271: plug, 274a: conductive layer, 274b: conductive layer, 274: plug, 280: display module, 281: display portion, 282: circuit portion, 283a: pixel circuit, 283: pixel circuit portion, 284a: pixel, 284: pixel portion, 285: terminal portion, 286: wiring portion, 290: FPC, 291: substrate, 292: substrate, 301A: substrate, 301B: substrate, 301: substrate, 310A: transistor, 310B: transistor, 310: transistor, 311: conductive layer, 312: low-resistance region, 313: insulating layer, 314: insulating layer, 315: element isolation layer, 320A: transistor, 320B: transistor, 320: transistor, 321: semiconductor layer, 323: insulating layer, 324: conductive layer, 325: conductive layer, 326: insulating layer, 327: conductive layer, 328: insulating layer, 329: insulating layer, 331: substrate, 332: insulating layer, 335: insulating layer, 336: insulating layer, 341: conductive layer, 342: conductive layer, 343: plug, 344: insulating layer, 345: insulating layer, 346: insulating layer, 347: bump, 348: adhesive layer, 351: substrate, 352: finger, 353: layer, 355: functional layer, 357: layer, 359: substrate, 700A: electronic device, 700B: electronic device, 721: housing, 723: wearing portion, 727: earphone portion, 750: earphone, 751: display panel, 753: optical member, 756: display region, 757: frame, 758: nose pad, 761: lower electrode, 762: upper electrode, 763a: light-emitting unit, 763b: light-emitting unit, 763c: light-emitting unit, 763: EL layer, 764: layer, 765: layer, 766: layer, 767: active layer, 768: layer, 771a: light-emitting layer, 771b: light-emitting layer, 771c: light-emitting layer, 771: light-emitting layer, 772a: light-emitting layer, 772b: light-emitting layer, 772c: light-emitting layer, 772: light-emitting layer, 773: light-emitting layer, 780a: layer, 780b: layer, 780c: layer, 780: layer, 781: layer, 782: layer, 785: charge-generation layer, 790a: layer, 790b: layer, 790c: layer, 790: layer, 791: layer, 792: layer, 800A: electronic device, 800B: electronic device, 820: display portion, 821: housing, 822: communication portion, 823: wearing portion, 824: control portion, 825: image capturing portion, 827: earphone portion, 832: lens, 6500: electronic device, 6501: housing, 6502: display portion, 6503: power button, 6504: button, 6505: speaker, 6506: microphone, 6507: camera, 6508: light source, 6510: protection member, 6511: display panel, 6512: optical member, 6513: touch sensor panel, 6515: FPC, 6516: IC, 6517: printed circuit board, 6518: battery, 7000: display portion, 7100: television device, 7101: housing, 7103: stand, 7111: remote control, 7200: laptop personal computer, 7211: housing, 7212: keyboard, 7213: pointing device, 7214: external connection port, 7300: digital signage, 7301: housing, 7303: speaker, 7311: information terminal, 7400: digital signage, 7401: pillar, 7411: information terminal, 9000: housing, 9001: display portion, 9002: camera, 9003: speaker, 9005: operation key, 9006: connection terminal, 9007: sensor, 9008: microphone, 9050: icon, 9051: information, 9052: information, 9053: information, 9054: information, 9055: hinge, 9101: portable information terminal, 9102: portable information terminal, 9103: tablet terminal, 9200: portable information terminal, 9201: portable information terminal

Claims

1. A display device comprising: a first light-emitting device;a second light-emitting device;a first sidewall insulating layer;a second sidewall insulating layer;a third sidewall insulating layer; andan insulating layer,wherein the first light-emitting device comprises a first conductive layer, a first layer over the first conductive layer, and a common electrode over the first layer,wherein the second light-emitting device comprises a second conductive layer, a second layer over the second conductive layer, and the common electrode over the second layer,wherein an end portion of the first conductive layer overlaps with an end portion of the first layer,wherein the first sidewall insulating layer is in contact with a side surface of the first conductive layer and a side surface of the first layer,wherein an end portion of the second conductive layer overlaps with an end portion of the second layer,wherein the second sidewall insulating layer is in contact with a side surface of the second conductive layer and a side surface of the second layer,wherein the third sidewall insulating layer is in contact with a side surface of the second sidewall insulating layer that is opposite to a side surface of the second sidewall insulating layer in contact with the side surface of the second conductive layer and the side surface of the second layer,wherein the insulating layer overlaps with the side surface and part of a top surface of each of the first conductive layer, the first layer, the second conductive layer, and the second layer, andwherein the common electrode is over the first layer, the second layer, and the insulating layer.

2. The display device according to claim 1, wherein the first conductive layer and the second conductive layer each comprise a material having a property of reflecting visible light.

3. The display device according to claim 1, further comprising a fourth sidewall insulating layer comprising the second sidewall insulating layer and the third sidewall insulating layer,wherein a thickness of the fourth sidewall insulating layer is larger than a thickness of the first sidewall insulating layer.

4. The display device according to claim 1, wherein the first sidewall insulating layer, the second sidewall insulating layer, and the third sidewall insulating layer each comprise an inorganic insulating material.

5. The display device according to claim 1, wherein the insulating layer has a tapered side surface.

6. The display device according to claim 1, wherein the insulating layer comprises an organic insulating material.

7. A method for fabricating a display device, comprising: forming a first conductive film;forming a first film comprising a first light-emitting substance over the first conductive film;forming a first mask film over the first film;forming a first conductive layer, a first layer, and a first mask layer by processing the first conductive film, the first film, and the first mask film such that side surfaces of the first conductive film, the first film, and the first mask film are aligned or substantially aligned with each other;forming a second conductive film over the first mask layer;forming a second film comprising a second light-emitting substance over the second conductive film;forming a second mask film over the second film; andforming a second conductive layer, a second layer, and a second mask layer and exposing a top surface of the first mask layer by processing the second conductive film, the second film, and the second mask film such that side surfaces of the second conductive film, the second film, and the second mask film are aligned or substantially aligned with each other.

8. The method for fabricating a display device, according to claim 7, wherein each of the first conductive film and the second conductive film is formed using a material having a property of reflecting visible light.

9. The method for fabricating a display device, according to claim 7, wherein the first film is formed using a material comprising the first light-emitting substance emitting blue light, andwherein the second film is formed using a material comprising the second light-emitting substance emitting visible light having a longer wavelength than blue light.

10. The method for fabricating a display device, according to claim 7, further comprising: forming a first insulating film over the first mask layer and the second mask layer after the second conductive layer, the second layer, and the second mask layer are formed;forming a second insulating film over the first insulating film;forming an insulating layer in a region between the first conductive layer and the second conductive layer by processing the second insulating film;processing the first insulating film, the first mask layer, and the second mask layer to expose a top surface of the first layer and a top surface of the second layer by etching treatment using the insulating layer as a mask; andforming a common electrode covering the first layer, the second layer, and the insulating layer.

11. The method for fabricating a display device, according to claim 10, wherein an aluminum oxide film is formed by an ALD method as the first insulating film, andwherein an aluminum oxide film is formed by an ALD method as each of the first mask film and the second mask film.

12. The method for fabricating a display device, according to claim 10, wherein the second insulating film is formed using a photosensitive acrylic resin.

13. The method for fabricating a display device, according to claim 10, wherein the etching treatment is divided into first etching treatment and second etching treatment,wherein, in the first etching treatment using the insulating layer as a mask, the first insulating film, the first mask layer, and the second mask layer are processed to remove part of the first insulating film and reduce a thickness of part of the first mask layer and a thickness of part of the second mask layer, andwherein, in the second etching treatment using the insulating layer as a mask after heat treatment, the part of the first mask layer and the part of the second mask layer are removed to expose the top surface of the first layer and the top surface of the second layer.

14. The method for fabricating a display device, according to claim 13, wherein the first etching treatment and the second etching treatment are performed by wet etching.

15. The method for fabricating a display device, according to claim 7, further comprising: forming a first sidewall insulating film in contact with a side surface of the first conductive layer, a side surface of the first layer, and a side surface and the top surface of the first mask layer after the first conductive layer, the first layer, and the first mask layer are formed;forming a first sidewall insulating layer in contact with the side surface of the first conductive layer and the side surface of the first layer by processing the first sidewall insulating film by anisotropic etching;forming a second sidewall insulating film in contact with a side surface of the second conductive layer, a side surface of the second layer, and a side surface and a top surface of the second mask layer after the second conductive layer, the second layer, and the second mask layer are formed; andforming a second sidewall insulating layer in contact with the side surface of the second conductive layer and the side surface of the second layer and forming a third sidewall insulating layer in contact with a side surface of the first sidewall insulating layer that is opposite to a side surface of the first sidewall insulating layer in contact with the first conductive layer, the first layer, and the first mask layer by processing the second sidewall insulating film by anisotropic etching.

16. The method for fabricating a display device, according to claim 15, wherein an aluminum oxide film is formed by an ALD method as each of the first sidewall insulating film and the second sidewall insulating film.