Display device

Abstract

Provided is a high-definition or high-resolution display device. This display device comprises a first light-emitting element and a second light-emitting element, the first light-emitting element and the second light-emitting element each having the function of emitting light of different colors. The first light-emitting element has a first pixel electrode, a first EL layer on the first pixel electrode, and a common electrode on the first EL layer. The second light-emitting element has a second pixel electrode, a second EL layer on the second pixel electrode, and a common electrode on the second EL layer. The first EL layer has a first layer on the first pixel electrode and a first light-emitting layer on the first layer. The first layer has a hole injection layer. The angle formed between a side surface of the first pixel electrode and the bottom surface of the first pixel electrode is 60 degrees to 140 degrees, inclusive. The ratio (T1 / T2) of the film thickness T1 of the first pixel electrode with respect to the film thickness T2 of the first layer being 0.5 or greater.

Description

display device

[0001] 1. Field of the Invention One embodiment of the present invention relates to a display device, a display module, and an electronic device. 2. Description of the Related Art One embodiment of the present invention relates to a manufacturing method of a display device.

[0002] One embodiment of the present invention is not limited to the above technical field, and examples of the technical field of one embodiment of the present invention include semiconductor devices, display devices, light-emitting devices, power storage devices, memory devices, electronic devices, lighting devices, input devices (e.g., touch sensors), input / output devices (e.g., touch panels), driving methods thereof, and manufacturing methods thereof.

[0003] BACKGROUND ART In recent years, information terminal devices such as mobile phones such as smartphones, tablet information terminals, and notebook PCs (personal computers) have become widespread. High-definition display panels are required for the display panels provided in these devices.

[0004] Representative examples of display devices applicable to the display panel include liquid crystal display devices, organic EL (Electro Luminescence) elements, light-emitting devices equipped with light-emitting elements such as light-emitting diodes (LEDs: Light Emitting Diodes), and electronic paper that displays using an electrophoresis method.

[0005] For example, the basic structure of an organic EL element is a layer containing a light-emitting organic compound sandwiched between a pair of electrodes. By applying a voltage to this element, light can be emitted from the light-emitting organic compound. A display device using such an organic EL element does not require a backlight, which is necessary in liquid crystal display devices and the like, and therefore can realize a thin, lightweight, high-contrast, and low-power display device. For example, an example of a display device using an organic EL element is described in Patent Document 1.

[0006] JP 2002-324673 A

[0007] As pixels become smaller and the pixel density increases, problems can arise that do not occur in displays with larger pixels. One such problem is crosstalk, an interference phenomenon in which unintended current flows between adjacent pixels.

[0008] For example, when a display is produced using light-emitting elements (hereinafter referred to as tandem elements) having a structure in which multiple light-emitting units are separated by a charge-generating layer, white light can be easily obtained, and therefore a full-color system is often adopted in which the same EL layer structure is applied to the light-emitting elements of all pixels, and a resonant structure or color filters are used to obtain the required light emission color for each pixel.

[0009] It is also possible to achieve full color by using a plurality of light-emitting elements with different luminescent colors without using color filters, etc. In this case, each pixel has a different EL layer structure, but layers other than the light-emitting layer, such as a hole injection layer, a hole transport layer, an electron injection layer, and an electron transport layer, are often provided as common layers.

[0010] A light-emitting element has a structure in which an EL layer is sandwiched between a pair of electrodes, and in an active matrix light-emitting element, one of the pair of electrodes is divided for each pixel, while the other electrode is formed to be shared by multiple pixels, so that the pixel is driven by controlling one of the electrodes divided for each pixel.

[0011] Here, when multiple light-emitting elements have part or all of their EL layers connected together as a common layer, if the common layer has high conductivity, current may also flow between the first electrode of the element to be driven and the common electrode (second electrode) present in the region of an adjacent pixel, resulting in crosstalk.

[0012] In view of the above, an object of one embodiment of the present invention is to provide a light-emitting element capable of suppressing the occurrence of crosstalk, and to provide a display device in which the occurrence of crosstalk is suppressed.

[0013] An object of one embodiment of the present invention is to provide a method for manufacturing a light-emitting element capable of suppressing crosstalk.An object of one embodiment of the present invention is to provide a method for manufacturing a display device in which crosstalk is suppressed.

[0014] 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-resolution display device.An object of one embodiment of the present invention is to provide a display device with a high aperture ratio.An object of one embodiment of the present invention is to provide a large-sized display device.An object of one embodiment of the present invention is to provide a small-sized display device.An object of one embodiment of the present invention is to provide a highly reliable display device.

[0015] An object of one embodiment of the present invention is to provide a method for manufacturing a high-resolution display device.An object of one embodiment of the present invention is to provide a method for manufacturing a high-resolution display device.An object of one embodiment of the present invention is to provide a method for manufacturing a display device with a high aperture ratio.An object of one embodiment of the present invention is to provide a method for manufacturing a large-sized display device.An object of one embodiment of the present invention is to provide a method for manufacturing a small-sized display device.An object of one embodiment of the present invention is to provide a method for manufacturing a highly reliable display device.An object of one embodiment of the present invention is to provide a method for manufacturing a display device with a high yield.

[0016] Note that the description of these problems does not preclude the existence of other problems. One embodiment of the present invention does not necessarily have to solve all of these problems. Problems other than these can be extracted from the description in the specification, drawings, and claims.

[0017] One embodiment of the present invention is a display device including a first light-emitting element and a second light-emitting element, the first light-emitting element and the second light-emitting element emitting light of different colors from each other. The first light-emitting element includes a first pixel electrode, a first EL layer over the first pixel electrode, and a common electrode over the first EL layer. The second light-emitting element includes a second pixel electrode, a second EL layer over the second pixel electrode, and a common electrode over the second EL layer. The first EL layer includes a first layer over the first pixel electrode and a first light-emitting layer over the first layer. The first layer includes a hole-injection layer. The first pixel electrode has a region where an angle formed between a side surface of the first pixel electrode and a bottom surface of the first pixel electrode is 60 degrees or more and 140 degrees or less. The ratio (T1 / T2) of a thickness T1 of the first pixel electrode to a thickness T2 of the first layer in contact with a top surface of the first pixel electrode is 0.5 or more.

[0018] Another embodiment of the present invention includes a first insulating layer, a first light-emitting element over the first insulating layer, and a second light-emitting element over the first insulating layer, the first light-emitting element and the second light-emitting element having a function of emitting light of different colors from each other, the first light-emitting element having a first pixel electrode, a first EL layer over the first pixel electrode, and a common electrode over the first EL layer, the second light-emitting element having a second pixel electrode, a second EL layer over the second pixel electrode, and a common electrode over the second EL layer, and the first EL layer has a first pixel electrode, a first EL layer over the second pixel electrode, and a common electrode over the second EL layer. a first insulating layer having a first insulating layer and a first light-emitting layer on the first layer, the first layer having a hole injection layer, the first insulating layer having a recess between the first pixel electrode and the second pixel electrode, a bottom extension line extending from the bottom of the recess to below the first pixel electrode in parallel to the bottom surface of the first pixel electrode, and a region having an angle of 60 degrees or more and 140 degrees or less between the side surface of the recess and the bottom extension line, and the ratio (ET / T2) of the shortest distance ET from the bottom extension line to the top surface of the first pixel electrode to the film thickness T2 of the first layer is 0.5 or more.

[0019] In any one of the display devices described above, it is preferable that the display device further comprises a second insulating layer in contact with a side surface of the first pixel electrode and a side surface of the second pixel electrode.

[0020] In any one of the display devices described above, the second insulating layer preferably contains an inorganic material.

[0021] In any one of the display devices described above, it is preferable that a third insulating layer be provided between the first pixel electrode and the second pixel electrode and below the common electrode.

[0022] In any one of the display devices described above, the third insulating layer preferably contains an organic material.

[0023] In the display device described in any one of the above, it is preferable that the second EL layer has a second layer on the second pixel electrode and a second light-emitting layer on the second layer, and that between the first light-emitting element and the second light-emitting element, a third insulating layer is arranged below the common electrode, a second insulating layer is arranged below the third insulating layer, and a first organic layer is arranged below the second insulating layer, and that the first organic layer, the first layer, and the second layer contain the same material.

[0024] In the display device described in any one of the above, it is preferable that a second organic layer and a third organic layer are provided on the first organic layer, the second organic layer contains the same material as the first light-emitting layer, and the third organic layer contains the same material as the second light-emitting layer.

[0025] In any one of the display devices described above, it is preferable that the upper surface of the first EL layer, the upper surface of the second EL layer, and the upper surface of the third insulating layer have regions in contact with the common electrode.

[0026] In any one of the display devices described above, the first layer preferably has a hole transport layer on a hole injection layer.

[0027] In any one of the display devices described above, the first EL layer preferably has an electron transporting layer on the first light-emitting layer.

[0028] In any one of the display devices described above, the first EL layer preferably has an electron injection layer between the electron transport layer and the common electrode.

[0029] According to one embodiment of the present invention, a light-emitting element capable of suppressing crosstalk can be provided.

[0030] According to one embodiment of the present invention, a method for manufacturing a light-emitting element capable of suppressing crosstalk can be provided. According to one embodiment of the present invention, a method for manufacturing a display device in which crosstalk is suppressed can be provided.

[0031] According to one embodiment of the present invention, a high-definition display device can be provided. According to one embodiment of the present invention, a high-resolution display device can be provided. According to one embodiment of the present invention, a display device with a high aperture ratio can be provided. According to one embodiment of the present invention, a large-sized display device can be provided. According to one embodiment of the present invention, a small-sized display device can be provided. According to one embodiment of the present invention, a highly reliable display device can be provided.

[0032] According to one embodiment of the present invention, a method for manufacturing a high-resolution display device can be provided. ... display device with a high aperture ratio can be provided. According to one embodiment of the present invention, a method for manufacturing a large-sized display device can be provided. According to one embodiment of the present invention, a method for manufacturing a small-sized display device can be provided. According to one embodiment of the present invention, a method for manufacturing a highly reliable display device can be provided. According to one embodiment of the present invention, a method for manufacturing a display device with a high yield can be provided.

[0033] 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. Effects other than these can be extracted from the description in the specification, drawings, and claims.

[0034] FIG. 1A is a top view showing an example of a display device. FIG. 1B is a cross-sectional view showing an example of a display device. FIGS. 2A to 2C are cross-sectional views showing an example of a display device. FIGS. 3A to 3C are cross-sectional views showing an example of a display device. FIGS. 4A to 4C are cross-sectional views showing an example of a display device. FIGS. 5A and 5B are cross-sectional views showing an example of a display device. FIGS. 6A and 6B are cross-sectional views showing an example of a display device. FIGS. 7A to 7F are cross-sectional views showing an example of a display device. FIGS. 8A to 8F are top views showing an example of a pixel. FIGS. 9A and 9B are top views showing an example of a manufacturing method of a display device. FIGS. 10A to 10C are cross-sectional views showing an example of a manufacturing method of a display device. FIGS. 11A to 11C are cross-sectional views showing an example of a manufacturing method of a display device. FIGS. 12A to 12C are cross-sectional views showing an example of a manufacturing method of a display device. FIGS. 13A to 13C are cross-sectional views showing an example of a manufacturing method of a display device. FIGS. 14A to 14C are cross-sectional views showing an example of a manufacturing method of a display device. 15A to 15F are diagrams showing configuration examples of a light-emitting element. FIG. 16 is a perspective view showing an example of a display device. FIG. 17A is a cross-sectional view showing an example of a display device. FIGS. 17B and 17C are cross-sectional views showing an example of a transistor. FIG. 18 is a cross-sectional view showing an example of a display device. FIG. 19 is a cross-sectional view showing an example of a display device. FIG. 20 is a cross-sectional view showing an example of a display device. FIGS. 21A to 21D are cross-sectional views showing an example of a display device. FIGS. 22A and 22B are perspective views showing an example of a display module. FIG. 23 is a cross-sectional view showing an example of a display device. FIG. 24 is a cross-sectional view showing an example of a display device. FIG. 25 is a cross-sectional view showing an example of a display device. FIG. 26 is a cross-sectional view showing an example of a display device. FIG. 27 is a cross-sectional view showing an example of a display device. FIG. 28A is a block diagram showing an example of a display device. FIGS. 28B to 28D are diagrams showing an example of a pixel circuit. FIGS. 29A to 29D are cross-sectional views showing an example of a transistor. FIGS. 30A and 30B are diagrams showing an example of an electronic device. FIGS. 31A and 31B are diagrams showing an example of an electronic device. 32A and 32B are cross-sectional views illustrating an example of an electronic device.33A to 33D are diagrams showing an example of an electronic device, and Fig. 34A to Fig. 34G are diagrams showing an example of an electronic device.

[0035] The embodiments will be described in detail with reference to the drawings. However, the present invention is not limited to the following description, and it will be readily understood by those skilled in the art that various changes can be made in form and detail without departing from the spirit and scope of the present invention. Therefore, the present invention should not be interpreted as being limited to the description of the embodiments shown below.

[0036] In the configuration of the invention described below, the same parts or parts having similar functions are denoted by the same reference numerals in different drawings, and repeated explanations thereof will be omitted. In addition, when referring to similar functions, the same hatch pattern may be used and no particular reference numeral may be assigned.

[0037] Furthermore, for ease of understanding, the position, size, range, etc. of each component shown in the drawings may not represent the actual position, size, range, etc. Therefore, the disclosed invention is not necessarily limited to the position, size, range, etc. disclosed in the drawings.

[0038] It should be noted that the terms "film" and "layer" can be interchangeable depending on the circumstances. For example, the term "conductive layer" can be changed to the term "conductive film." Or, for example, the term "insulating film" can be changed to the term "insulating layer."

[0039] In this specification, the term "island-like" refers to a state in which two or more layers made of the same material and formed in the same process are physically separated. For example, an island-like light-emitting layer refers to a state in which the light-emitting layer is physically separated from the adjacent light-emitting layer.

[0040] In this specification, "parallel" refers to, for example, a state in which two straight lines are arranged at an angle of -10° or more and 10° or less. Therefore, it also includes the case of an angle of -5° or more and 5° or less. Furthermore, "perpendicular" and "orthogonal" refer to, for example, a state in which two straight lines are arranged at an angle of 80° or more and 100° or less. Therefore, it also includes the case of an angle of 85° or more and 95° or less.

[0041] Embodiment 1 In this embodiment, a display device according to one embodiment of the present invention and a manufacturing method thereof will be described with reference to FIGS.

[0042] A display device according to one embodiment of the present invention has a display portion in which pixels are arranged in a matrix, and can display an image. The pixels include a plurality of sub-pixels that emit different light colors, and the plurality of sub-pixels include different light-emitting layers and a common layer that is provided in common to the sub-pixels. The common layer can simplify the manufacturing process and reduce manufacturing costs.

[0043] In this specification, a pixel refers to, for example, one element whose brightness can be controlled. As an example, one pixel refers to one color element, and the brightness is expressed by that one color element. In the case of a color display device consisting of R (red), G (green), and B (blue) color elements, the smallest unit of an image is composed of three pixels: an R pixel, a G pixel, and a B pixel. In this case, each of the RGB pixels can also be called a sub-pixel, and the three RGB sub-pixels can also be called a pixel. Full-color display can be achieved by using light-emitting devices corresponding to each color in the sub-pixels within each pixel.

[0044] The light-emitting device may be, for example, an organic light-emitting diode (OLED) or a quantum-dot light-emitting diode (QLED). Examples of light-emitting materials that the light-emitting device may have include fluorescent materials, phosphorescent materials, inorganic compounds (such as quantum dot materials), and thermally activated delayed fluorescence (TADF) materials.

[0045] When the light-emitting device of each subpixel is formed using an EL device, the EL layer of the EL device includes a light-emitting layer. The EL layer preferably includes, in addition to the light-emitting layer, one or more of a hole injection layer, a hole transport layer, an electron transport layer, and an electron injection layer. In this case, the EL layer of each subpixel may have a different light-emitting layer, and some of the EL layers (such as the hole injection layer, the hole transport layer, the electron injection layer, and the electron transport layer) may be formed as a common layer. For example, in a display device having three RGB subpixels, the R subpixel has a first EL layer, the G subpixel has a second EL layer, and the B subpixel has a third EL layer. The first light-emitting layer of the first EL layer, the second light-emitting layer of the second EL layer, and the third light-emitting layer of the third EL layer may be formed from different materials, while some of the EL layers (such as the hole injection layer, the hole transport layer, the electron injection layer, and the electron transport layer) may be formed as a common layer using the same material. The EL layer may have a part of the EL layer (such as a hole injection layer, a hole transport layer, an electron injection layer, and an electron transport layer) that is not formed as a common layer.

[0046] When the light-emitting devices of each subpixel are formed using EL devices that emit different light colors, the EL layer of the EL device can be formed in an island shape using a metal mask, and parts of the EL layer (e.g., a hole injection layer, a hole transport layer, an electron injection layer, and an electron transport layer) can be formed as common layers. However, some layers included in the EL layer have relatively high conductivity, and providing a highly conductive layer common to each pixel can cause leakage current between pixels. In particular, as display devices become higher in resolution or aperture ratio and the distance between pixels becomes smaller, the leakage current can become significant, potentially causing a deterioration in the display quality of the display device. Therefore, in a display device according to one embodiment of the present invention, at least parts of the EL layer in each pixel are formed in an island shape, thereby achieving higher resolution and higher reliability of the display device.

[0047] In a manufacturing method of a display device according to one embodiment of the present invention, a conductive layer is formed over the entire surface, and then a resist mask is formed at a position corresponding to each pixel. The conductive layer is then processed into an island shape to form a first electrode (also referred to as a lower electrode of a light-emitting element). At this time, a step having a height T1 is formed in a region between adjacent first electrodes. Next, a part of an EL layer is formed over the entire surface. This part of the EL layer formed here can be referred to as a first layer. Here, when the angle between the side surface of the first electrode and the bottom surface of the first electrode is a taper angle θ and the thickness of the first layer is T2, T1 / T2 is 0.5 or more, preferably 0.8 or more, more preferably 1 or more, and even more preferably 1.5 or more. When θ is 60 degrees or more and 140 degrees or less, preferably 70 degrees or more and 140 degrees or less, and even more preferably 80 degrees or more and 140 degrees or less, a region where the first layer is not formed can be obtained on the side surface of the first electrode. In this case, the first layer is separated into islands at the same position as the first electrode, allowing the first layer of each pixel to be formed in a self-aligned manner. If the insulating layer below the adjacent first electrodes is removed to form a concave step (recess), the height T1 of the step between the adjacent first electrodes is the sum of the film thickness of the first electrode and the depth of the step in the insulating layer. The first layer preferably includes a carrier injection layer (hole injection layer or electron injection layer), and more preferably includes a carrier transport layer (hole transport layer or electron transport layer) between the first layer and the light-emitting layer in addition to the carrier injection layer.

[0048] As described above, the region on the side of the island-shaped electrode where the upper layer is not formed is sometimes called a step portion or step region. As described above, it is preferable to have a region (step portion) on the side of the first electrode where the first layer is not formed. However, even if the first layer is thin on the side of the first electrode, the effect of electrically isolating the first layer of each pixel may be obtained. Therefore, it is not necessarily necessary to have a region on the side of the first electrode where the first layer is not formed.

[0049] Next, a light-emitting layer is formed on the first layer of each pixel. For example, in the case of a display device having three sub-pixels of RGB in one pixel, a light-emitting layer that emits red light, a light-emitting layer that emits green light, and a light-emitting layer that emits blue light are formed, respectively. The light-emitting layer can be formed, for example, by a vapor deposition method using a metal mask. Alternatively, an inkjet method may be used to form the light-emitting layer. The light-emitting layer may have island-shaped regions on the side surfaces of the first electrode where the light-emitting layer is not formed, similar to the first layer, or the light-emitting layer may be formed. Furthermore, there may be regions where light-emitting layers that emit different colors of light overlap between adjacent first electrodes.

[0050] Next, a second layer is formed on the entire surface as part of the EL layer. For example, if a hole injection layer and a hole transport layer are formed as the first layer, an electron transport layer is formed as the second layer. Also, for example, if an electron injection layer and an electron transport layer are formed as the first layer, a hole transport layer is formed as the second layer. The second layer may be separated into islands like the first layer, but it does not have to be separated into islands.

[0051] Next, an insulating layer is formed over the entire surface. The insulating layer is then processed so as to leave the insulating layer in the recesses between adjacent first electrodes. In this case, the side of the first electrode may have a first region directly in contact with the first layer and a second region directly in contact with the insulating layer. The insulating layer may be a single layer, but preferably two or more layers. When two or more insulating layers are used, the insulating layer formed first can be designated by an ordinal number, such as the first insulating layer, the second insulating layer, and so on. For example, when two insulating layers are used, using a material with high solvent resistance, moisture barrier properties, and gas barrier properties as the material for the first insulating layer can reduce damage to the EL layer during the manufacturing process of the display device and improve the reliability of the light-emitting device. Furthermore, using a liquid raw material in forming the second insulating layer can fill the recesses between adjacent pixels, making it easier to obtain a flat shape.

[0052] Next, the insulating layer is removed at the positions where the first electrode, the first layer, the light-emitting layer, the second layer, and the insulating layer overlap, exposing the second layer. Then, a second electrode (sometimes referred to as an upper electrode of the light-emitting element) is formed so as to contact at least the exposed portions of the EL layer of all pixels. Here, if the recesses between adjacent pixels are filled with an insulating layer, the second electrode can be formed without interruption in the recesses between adjacent pixels, thereby suppressing discontinuities of the second electrode. A third layer may be formed before the formation of the second electrode. The third layer may be, for example, an electron injection layer or a hole injection layer. Alternatively, the third layer may be, for example, an electron transport layer and an electron injection layer, or a hole transport layer and a hole injection layer.

[0053] As described above, in the method for manufacturing a display device according to one embodiment of the present invention, when the first layer is deposited over the entire surface as part of the EL layer, the first layer is separated in a self-aligned manner at the position of the lower electrode (first electrode). Therefore, a light-emitting element capable of suppressing crosstalk can be obtained. Furthermore, a high-definition display device or a display device with a high aperture ratio, which has been difficult to achieve until now, can be realized. Furthermore, by filling the recesses between adjacent pixels with an insulating layer, disconnection defects during the formation of the upper electrode of the EL layer can be suppressed, thereby improving the productivity and reliability of the light-emitting device. Furthermore, as described above, in the island-shaped EL layer, the periphery of the EL layer that is not in contact with the upper electrode and the lower electrode is covered with a material having high solvent resistance, moisture barrier properties, and gas barrier properties. This reduces damage to the EL layer during the manufacturing process of the display device, thereby improving the reliability of the light-emitting device.

[0054] In this specification, etc., a device fabricated using a metal mask or an FMM (fine metal mask, high-resolution metal mask) may be referred to as a device with an MM (metal mask) structure. Also, in this specification, etc., a device fabricated without using a metal mask or an FMM may be referred to as a device with an MML (metal maskless) structure.

[0055] In a light-emitting device, it is not necessary to form all layers constituting the EL layer in an island shape, and some layers can be formed in the same process. In addition, in a manufacturing method of a display device according to one embodiment of the present invention, after some layers constituting the EL layer are formed in an island shape for each pixel, part of the insulating layer (which may be referred to as a protective insulating layer or a barrier layer) is removed, and the remaining layers constituting the EL layer (for example, a carrier injection layer) and a common electrode (which may also be referred to as an upper electrode) can be formed in common.

[0056] On the other hand, the carrier injection layer is often a relatively highly conductive layer in light-emitting devices. Therefore, contact between the carrier injection layer and the side surface of the island-shaped EL layer may cause a short circuit in the light-emitting device. Even when the carrier injection layer is provided in an island shape and only the common electrode is formed in common between the light-emitting devices, contact between the common electrode and the side surface of the island-shaped EL layer or the side surface of the pixel electrode may cause a short circuit in the light-emitting device. To address this concern, a display device according to one embodiment of the present invention includes insulating layers (the first insulating layer and the second insulating layer) covering the side surfaces of the island-shaped EL layer (e.g., the light-emitting layer) and the pixel electrode. This prevents at least a portion of the island-shaped EL layer and the pixel electrode from contacting the carrier injection layer or the common electrode. This prevents short circuits in the light-emitting device and improves the reliability of the light-emitting device. The common electrode may also include the carrier injection layer.

[0057] A display device according to one embodiment of the present invention includes a pixel electrode functioning as an anode, a hole-injection layer, a hole-transport layer, a light-emitting layer, and an electron-transport layer, which are provided in this order over the pixel electrode, insulating layers provided so as to cover side surfaces of the pixel electrode, the hole-injection layer, the hole-transport layer, the light-emitting layer, and the electron-transport layer, an electron-injection layer provided over the electron-transport layer, and a common electrode functioning as a cathode, where at least the pixel electrode and the hole-injection layer are provided in island shapes.

[0058] Alternatively, a display device according to one embodiment of the present invention includes a pixel electrode functioning as a cathode, an electron-injection layer, an electron-transport layer, a light-emitting layer, and a hole-transport layer which are provided in this order over the pixel electrode, insulating layers provided so as to cover side surfaces of the pixel electrode, the electron-injection layer, the electron-transport layer, the light-emitting layer, and the hole-transport layer, a hole-injection layer provided over the hole-transport layer, and a common electrode which is provided over the hole-injection layer and functions as an anode, where at least the pixel electrode and the electron-injection layer are provided in an island shape.

[0059] Alternatively, a display device according to one embodiment of the present invention includes a pixel electrode, a first light-emitting unit over the pixel electrode, an intermediate layer (also referred to as a charge generation layer) over the first light-emitting unit, a second light-emitting unit over the intermediate layer, insulating layers provided so as to cover side surfaces of the pixel electrode, the first light-emitting unit, the intermediate layer, and the second light-emitting unit, and a common electrode provided over the second light-emitting unit. Note that a layer common to light-emitting devices of each color may be provided between the second light-emitting unit and the common electrode. Here, at least the pixel electrode and the first layer of the first light-emitting unit are provided in an island shape.

[0060] Among EL layers, the hole injection layer, the electron injection layer, the charge generation layer, and the like are often layers with relatively high conductivity. In the display device of one embodiment of the present invention, the side surfaces of these layers are covered with an insulating layer, so that contact with a common electrode or the like can be suppressed. Therefore, short circuits in the light-emitting device can be suppressed, and the reliability of the light-emitting device can be improved.

[0061] A display device according to one embodiment of the present invention includes an insulating layer covering each of a side surface of the pixel electrode, a side surface of the first layer, a side surface of the light-emitting layer, and a side surface of the second layer. In a manufacturing process of the display device, the first layer can be formed in a self-aligned manner. Therefore, one embodiment of the present invention provides a manufacturing method of a display device with fewer manufacturing steps and low manufacturing costs. Furthermore, the insulating layer prevents contact between the pixel electrode and the carrier injection layer or the common electrode, thereby preventing short circuits in the light-emitting device.

[0062] The insulating layer between adjacent pixel electrodes may have a single-layer structure or a laminated structure. In particular, a two-layer insulating layer is preferably used. For example, since the first insulating layer is formed in contact with the EL layer, it is preferably formed using an inorganic insulating material. In particular, it is preferably formed using atomic layer deposition (ALD), which causes less film damage. Alternatively, it is preferable to form the inorganic insulating layer using sputtering, chemical vapor deposition (CVD), or plasma enhanced chemical vapor deposition (PECVD), which have a faster film formation rate than ALD. This allows for the production of a highly reliable display device with high productivity. Furthermore, it is preferable to form the second insulating layer using an organic material so as to planarize the recesses between adjacent pixels.

[0063] For example, an aluminum oxide film formed by an ALD method can be used for the first insulating layer, and a photosensitive organic resin film can be used for the second insulating layer.

[0064] [Structure Example 1 of Display Device] FIGS. 1A and 1B illustrate a display device of one embodiment of the present invention.

[0065] 1A shows a top view of a display device 100. The display device 100 has a display section in which a plurality of pixels 110 are arranged in a matrix, and a connection section 140 on the outside of the display section.

[0066] A stripe arrangement is applied to the pixel 110 shown in Fig. 1A. The pixel 110 shown in Fig. 1A is composed of three subpixels, 110a, 110b, and 110c. The subpixels 110a, 110b, and 110c each have a light-emitting device 130a that emits red light, a light-emitting device 130b that emits green light, and a light-emitting device 130c that emits blue light (hereinafter, these may be collectively referred to as light-emitting devices 130).

[0067] FIG. 1B shows a cross-sectional view taken along the dashed line X1-X2 in FIG. 1A.

[0068] 1, the sub-pixels 110a, 110b, and 110c each have a light-emitting device 130a that emits red light, a light-emitting device 130b that emits green light, and a light-emitting device 130c that emits blue light. Note that the configuration of the sub-pixels 110a, 110b, and 110c is not limited to the three colors of red (R), green (G), and blue (B), and may be three colors of yellow (Y), cyan (C), and magenta (M), for example.

[0069] 1A shows an example in which subpixels of different colors are arranged side by side in the X direction, and subpixels of the same color are arranged side by side in the Y direction. Note that subpixels of different colors may also be arranged side by side in the Y direction, and subpixels of the same color may also be arranged side by side in the X direction.

[0070] 1A shows an example in which the connection unit 140 is located below the display unit when viewed from above, but this is not particularly limited. The connection unit 140 only needs to be located in at least one position on the upper, right, left, or lower side of the display unit when viewed from above, and may be located so as to surround all four sides of the display unit. Furthermore, the connection unit 140 may be singular or plural.

[0071] As shown in FIG. 1B, the display device 100 has light-emitting devices 130a, 130b, and 130c provided on a layer 101 including transistors, and a protective layer 131 provided to cover these light-emitting devices.

[0072] The display device of one embodiment of the present invention may be any of a top emission type that emits light in a direction opposite to a substrate on which a light-emitting device is formed, a bottom emission type that emits light toward a substrate on which a light-emitting device is formed, and a dual emission type that emits light from both sides.

[0073] The transistor-containing layer 101 may have a stacked structure in which, for example, a plurality of transistors are provided on a substrate and an insulating layer is provided to cover these transistors. The transistor-containing layer 101 may have a recess between adjacent light-emitting devices. For example, a recess may be provided in an insulating layer located on the outermost surface of the transistor-containing layer 101. Configuration examples of the transistor-containing layer 101 will be described later in Embodiments 3 and 4.

[0074] A light-emitting device has an EL layer between a pair of electrodes, one of which may be referred to as a pixel electrode and the other as a common electrode in this specification and the like.

[0075] A light-emitting device has a pair of electrodes, one of which functions as an anode and the other as a cathode. In the following, an example will be described in which the pixel electrode functions as the anode and the common electrode functions as the cathode.

[0076] The light-emitting device 130a includes a pixel electrode 111a on a layer 101 including a transistor, an island-shaped first layer 112 on the pixel electrode 111a, a first light-emitting layer 113a on the first layer 112, a second layer 114 on the first light-emitting layer 113a, a third layer 115 on the second layer 114, and a common electrode 116 on the third layer 115. In the light-emitting device 130a, the first layer 112, the first light-emitting layer 113a, the second layer 114, and the third layer 115 can be collectively referred to as an EL layer 103a. Note that a configuration example of the light-emitting device will be described later in Embodiment 2.

[0077] Light-emitting device 130b has pixel electrode 111b on transistor-containing layer 101, island-shaped first layer 112 on pixel electrode 111b, second light-emitting layer 113b on first layer 112, second layer 114 on second light-emitting layer 113b, third layer 115 on second layer 114, and common electrode 116 on third layer 115. In light-emitting device 130b, first layer 112, second light-emitting layer 113b, second layer 114, and third layer 115 can be collectively referred to as EL layer 103b.

[0078] Light-emitting device 130c has pixel electrode 111c on transistor-containing layer 101, island-shaped first layer 112 on pixel electrode 111c, third light-emitting layer 113c on first layer 112, second layer 114 on third light-emitting layer 113c, third layer 115 on second layer 114, and common electrode 116 on third layer 115. In light-emitting device 130c, first layer 112, third light-emitting layer 113c, second layer 114, and third layer 115 can be collectively referred to as EL layer 103c.

[0079] The EL layer 103a of the light-emitting device 130a, the EL layer 103b of the light-emitting device 130b, and the EL layer 103c of the light-emitting device 130c may be collectively referred to as the EL layer 103. Furthermore, the first light-emitting layer 113a of the light-emitting device 130a, the second light-emitting layer 113b of the light-emitting device 130b, and the third light-emitting layer 113c of the light-emitting device 130c may be collectively referred to as the light-emitting layer 113.

[0080] The light-emitting devices of each color share the same film as the common electrode 116. The common electrode shared by all the light-emitting devices is electrically connected to a conductive layer provided in the connection section 140. This causes the common electrodes of the light-emitting devices to have the same potential.

[0081] Of the pixel electrode and the common electrode, the electrode from which light is extracted is preferably made of a conductive film that transmits visible light, and the electrode from which light is not extracted is preferably made of a conductive film that reflects visible light.

[0082] The pair of electrodes (pixel electrode and common electrode) of the light-emitting device can be formed from a material such as a metal, an alloy, an electrically conductive compound, or a mixture thereof. Specific examples include indium tin oxide (In-Sn oxide, also referred to as ITO), In-Si-Sn oxide (also referred to as ITSO), indium zinc oxide (In-Zn oxide), In-W-Zn oxide, an alloy containing aluminum (aluminum alloy) such as an alloy of aluminum, nickel, and lanthanum (Al-Ni-La), and an alloy of silver, palladium, and copper (Ag-Pd-Cu, also referred to as APC). Other examples of the metals that can be used include aluminum (Al), titanium (Ti), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), gallium (Ga), zinc (Zn), indium (In), tin (Sn), molybdenum (Mo), tantalum (Ta), tungsten (W), palladium (Pd), gold (Au), platinum (Pt), silver (Ag), yttrium (Y), and neodymium (Nd), as well as alloys containing appropriate combinations of these metals. Other examples of the metals that can be used include elements belonging to Group 1 or Group 2 of the periodic table (e.g., lithium (Li), cesium (Cs), calcium (Ca), and strontium (Sr)), rare earth metals such as europium (Eu), and ytterbium (Yb), as well as alloys containing appropriate combinations of these metals, graphene, and the like.

[0083] The light-emitting device preferably has a micro-optical resonator (microcavity) structure. Therefore, one of a pair of electrodes of the light-emitting device preferably has a transmissive and reflective electrode for visible light, and the other preferably has a reflective electrode for visible light. By having the light-emitting device have a microcavity structure, the light emitted from the light-emitting layer can be resonated between the two electrodes, thereby intensifying the light emitted from the light-emitting device.

[0084] The semi-transmitting / semi-reflective electrode can have a laminated structure of a reflective electrode and an electrode that is transparent to visible light (also called a transparent electrode).

[0085] The light transmittance of the transparent electrode is 40% or more. For example, it is preferable to use an electrode with a visible light (light with a wavelength of 400 nm or more and less than 750 nm) transmittance of 40% or more for a light-emitting device. The visible light reflectance of the semi-transparent / semi-reflective electrode is 10% or more and 95% or less, preferably 30% or more and 80% or less. The visible light reflectance of the reflective electrode is 40% or more and 100% or less, preferably 70% or more and 100% or less. The resistivity of these electrodes is 1×10 −２ Preferably, it is Ωcm or less.

[0086] The first layer 112 is provided in an island shape on each pixel electrode 111 (111a, 111b, 111c) of each pixel. The EL layer 103a, the EL layer 103b, and the EL layer 103c each have a light-emitting layer 113 (113a, 113b, 113c).

[0087] The light-emitting layer is a layer containing a light-emitting material. The light-emitting layer can have one or more light-emitting materials. Examples of the light-emitting material include fluorescent materials, phosphorescent materials, TADF materials, and quantum dot materials.

[0088] Examples of fluorescent materials include pyrene derivatives, anthracene derivatives, triphenylene derivatives, fluorene derivatives, carbazole derivatives, dibenzothiophene derivatives, dibenzofuran derivatives, dibenzoquinoxaline derivatives, quinoxaline derivatives, pyridine derivatives, pyrimidine derivatives, phenanthrene derivatives, and naphthalene derivatives.

[0089] Examples of phosphorescent materials include organometallic complexes (particularly iridium complexes) having a 4H-triazole skeleton, a 1H-triazole skeleton, an imidazole skeleton, a pyrimidine skeleton, a pyrazine skeleton, or a pyridine skeleton; organometallic complexes (particularly iridium complexes) having a phenylpyridine derivative having an electron-withdrawing group as a ligand; platinum complexes; and rare earth metal complexes.

[0090] The light-emitting layer may contain one or more organic compounds (host materials, assist materials, etc.) in addition to a light-emitting substance (guest material). As the one or more organic compounds, one or both of a hole-transporting material and an electron-transporting material can be used. Furthermore, as the one or more organic compounds, a bipolar material or a TADF material can be used.

[0091] The light-emitting layer preferably includes, for example, a phosphorescent material and a hole-transporting material and an electron-transporting material that are a combination that easily forms an exciplex. This configuration allows for efficient emission using Exciplex-Triple Energy Transfer (ExTET), which is energy transfer from the exciplex to the light-emitting material (phosphorescent material). By selecting a combination that forms an exciplex that emits light that overlaps with the wavelength of the lowest-energy absorption band of the light-emitting material, energy transfer becomes smooth, allowing for efficient emission. This configuration simultaneously enables high efficiency, low-voltage operation, and long life of the light-emitting device.

[0092] The EL layer 103 a, the EL layer 103 b, and the EL layer 103 c may further include a layer containing a substance with high hole-injection properties, a substance with high hole-transport properties, a hole-blocking material, a substance with high electron-transport properties, a substance with high electron-injection properties, an electron-blocking material, a bipolar substance (a substance with high electron-transport properties and high hole-transport properties), or the like, as a layer other than the light-emitting layer.

[0093] The light-emitting device can be made of either a low-molecular-weight compound or a high-molecular-weight compound, and may contain an inorganic compound. The layers constituting the light-emitting device can be formed by a method such as vapor deposition (including vacuum vapor deposition), sputtering, printing, inkjet printing, or coating.

[0094] For example, the first layer 112 may have a hole injection layer or an electron injection layer. Furthermore, the first layer 112 may further have a hole transport layer or an electron transport layer in addition to the hole injection layer or the electron injection layer. For example, when the pixel electrode 111 is an anode, the first layer 112 may be a hole injection layer, or a hole injection layer and a hole transport layer. Furthermore, for example, when the pixel electrode 111 is a cathode, the first layer 112 may be an electron injection layer, or an electron injection layer and an electron transport layer.

[0095] Each of the light-emitting layers 113 (113a, 113b, 113c) preferably has a carrier transport layer as the second layer 114 on the light-emitting layer 113. This prevents the light-emitting layer 113 from being exposed to the outermost surface during the manufacturing process of the display device 100, thereby reducing damage to the light-emitting layer 113. This improves the reliability of the light-emitting device. For example, when the pixel electrode 111 is an anode, the second layer 114 can be an electron transport layer. Furthermore, for example, when the pixel electrode 111 is a cathode, the second layer 114 can be a hole transport layer.

[0096] In the EL layer 103, a carrier injection layer (hole injection layer or electron injection layer) may be formed on the second layer 114 as the third layer 115. For example, when the pixel electrode 111 is an anode, the third layer 115 can be an electron injection layer. Also, for example, when the pixel electrode 111 is a cathode, the third layer 115 can be a hole injection layer.

[0097] The hole injection layer is a layer that injects holes from the anode into the hole transport layer and contains a material with high hole injection properties, such as an aromatic amine compound and a composite material containing a hole transport material and an acceptor material (electron acceptor material).

[0098] The hole transport layer is a layer that transports holes injected from the anode by the hole injection layer to the light emitting layer. The hole transport layer is a layer that contains a hole transporting material. Examples of the hole transporting material include 10 −６ cm ２A substance having a hole mobility of 1 / Vs or more is preferred. Note that other substances can also be used as long as they have a higher hole transporting property than electron transporting property. As the hole transporting material, a material having a high hole transporting property, such as a π-electron-rich heteroaromatic compound (e.g., a carbazole derivative, a thiophene derivative, a furan derivative, etc.) or an aromatic amine (a compound having an aromatic amine skeleton), is preferred.

[0099] The electron transport layer is a layer that transports electrons 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 transporting material. The electron transporting material is a material having a molecular weight of 1×10 −６ cm ２ A substance having an electron mobility of 1 / Vs or more is preferred. Note that other substances can also be used as long as they have a higher electron transporting property than holes. Examples of electron-transporting materials that can be used include metal complexes having a quinoline skeleton, metal complexes having a benzoquinoline skeleton, metal complexes having an oxazole skeleton, and metal complexes having a thiazole skeleton, as well as oxadiazole derivatives, triazole derivatives, imidazole derivatives, oxazole derivatives, thiazole derivatives, phenanthroline derivatives, quinoline derivatives having a quinoline ligand, benzoquinoline derivatives, quinoxaline derivatives, dibenzoquinoxaline derivatives, pyridine derivatives, bipyridine derivatives, pyrimidine derivatives, and other π-electron-deficient heteroaromatic compounds including nitrogen-containing heteroaromatic compounds.

[0100] The electron transport layer may have a laminated structure, and may have a hole blocking layer in contact with the light-emitting layer for blocking holes that pass through the light-emitting layer from the anode side to the cathode side.

[0101] The electron injection layer is a layer that injects electrons from the cathode to the electron transport layer and contains a material with high electron injection properties. Examples of the material with high electron injection properties include alkali metals, alkaline earth metals, and compounds thereof. Examples of the material with high electron injection properties include a composite material containing an electron transport material and a donor material (electron donor material).

[0102] The electron injection layer may be formed of, for example, lithium, cesium, ytterbium, lithium fluoride (LiF), cesium fluoride (CsF), calcium fluoride (CaF ｘ , where X is an arbitrary number), 8-(quinolinolato)lithium (abbreviation: Liq), 2-(2-pyridyl)phenolatolithium (abbreviation: LiPP), 2-(2-pyridyl)-3-pyridinolatolithium (abbreviation: LiPPy), 4-phenyl-2-(2-pyridyl)phenolatolithium (abbreviation: LiPPP), lithium oxide (LiO ｘ , where X is an arbitrary number), an alkali metal such as cesium carbonate, an alkaline earth metal, or a compound thereof can be used. The electron injection layer may have a stacked structure of two or more layers. For example, the stacked structure may have a structure in which lithium fluoride is used in the first layer and ytterbium is provided in the second layer.

[0103] Alternatively, an electron transporting material may be used for the electron injection layer. For example, a compound having an unshared electron pair and an electron-deficient heteroaromatic ring may be used as the electron transporting material. Specifically, a compound having at least one of a pyridine ring, a diazine ring (pyrimidine ring, pyrazine ring, pyridazine ring), and a triazine ring may be used.

[0104] The organic compound having an unshared electron pair preferably has a lowest unoccupied molecular orbital (LUMO) level of −3.6 eV to −2.3 eV. Generally, the highest occupied molecular orbital (HOMO) level and the LUMO level of an organic compound can be estimated by cyclic voltammetry (CV), photoelectron spectroscopy, optical absorption spectroscopy, inverse photoelectron spectroscopy, or the like.

[0105] For example, 4,7-diphenyl-1,10-phenanthroline (abbreviation: BPhen), 2,9-di(naphthalen-2-yl)-4,7-diphenyl-1,10-phenanthroline (abbreviation: NBPhen), 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), etc. can be used as the organic compound having an unshared electron pair. Note that NBPhen has a higher glass transition temperature (Tg) and is superior in heat resistance compared to BPhen.

[0106] In the case of fabricating a light-emitting device with a tandem structure, an intermediate layer is provided between two light-emitting units, which has the function of injecting electrons into one of the two light-emitting units and holes into the other when a voltage is applied between a pair of electrodes.

[0107] For example, a material applicable to an electron injection layer, such as lithium, can be suitably used for the intermediate layer. For example, a material applicable to a hole injection layer can be suitably used for the intermediate layer. For example, a layer containing a hole transport material and an acceptor material (electron acceptor material) can be used for the intermediate layer. For example, a layer containing an electron transport material and a donor material can be used for the intermediate layer. By forming an intermediate layer having such a layer, an increase in driving voltage can be suppressed when light-emitting units are stacked.

[0108] The side surfaces of the pixel electrode 111, the first layer 112, the light-emitting layer 113, and the second layer 114 are covered with the insulating layer 125 and the insulating layer 127. This prevents the third layer 115 (and / or the common electrode 116) from coming into contact with any of the side surfaces of the pixel electrode 111, the first layer 112, the light-emitting layer 113, and the second layer 114, thereby preventing short circuits in the light-emitting device.

[0109] Furthermore, when the EL layer 103 (103a, 103b, 103c) has a tandem structure, the side surfaces of the plurality of light-emitting units and the intermediate layer included in these layers are also covered with the insulating layer 125 and the insulating layer 127. This prevents the third layer 115 (and / or the common electrode 116) from coming into contact with any of the side surfaces of the plurality of light-emitting units and the intermediate layer, thereby preventing short circuits in the light-emitting device.

[0110] The insulating layer 125 preferably covers at least the side surface of the pixel electrode 111. Furthermore, the insulating layer 125 preferably covers the side surfaces of the first layer 112, the light-emitting layer 113, and the second layer 114. The insulating layer 125 can be configured to be in contact with one or more side surfaces of the pixel electrode 111 and the second layer 114. The insulating layer 125 is preferably an insulating layer containing an inorganic material.

[0111] The insulating layer 127 is provided on the insulating layer 125 so as to fill the recesses formed in the insulating layer 125. The insulating layer 127 can be configured to overlap the side surfaces of the pixel electrode 111, the first layer 112, the light-emitting layer 113, and the second layer 114 via the insulating layer 125. The insulating layer 127 is preferably an insulating layer containing an organic material. Note that the insulating layer 125 is disposed below the insulating layer 127, and the organic layer 112G and the like are disposed below the insulating layer 125. By including the organic layer 112G and the like, the shape of the insulating layer 127 after filling can sometimes be made flatter.

[0112] Note that either the insulating layer 125 or the insulating layer 127 does not necessarily have to be provided. For example, when the insulating layer 125 is not provided, the insulating layer 127 can be configured to be in contact with at least a part of the side surface of the EL layer 103. The configuration in which the insulating layer 125 or the insulating layer 127 is not provided can reduce the number of manufacturing steps of the display device. On the other hand, by providing the insulating layer 125 containing an inorganic material in contact with the side surface of the first layer 112, the light-emitting layer 113, and / or the second layer 114, the effect of suppressing impurities from being mixed into these layers can be enhanced. Furthermore, the insulating layer 127 can improve the flatness of the formation surfaces of the third layer 115 and the common electrode 116.

[0113] The third layer 115 and the common electrode 116 are provided over the second layer 114, 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 between a region where the pixel electrode 111 is provided and a region where the pixel electrode 111 is not provided (a region between light-emitting devices). In a display device according to one embodiment of the present invention, the insulating layer 125 and the insulating layer 127 can flatten the step, thereby improving the coverage of the third layer 115 and the common electrode 116. Therefore, poor connection due to a step in the common electrode 116 can be suppressed. Alternatively, an increase in electrical resistance due to a local thinning of the common electrode 116 due to the step can be suppressed. Note that the third layer 115 may be collectively referred to as the common electrode 116.

[0114] In order to improve the flatness of the surfaces on which the third layer 115 and the common electrode 116 are formed, it is preferable that the height of the top surface of the insulating layer 125 and the top surface of the insulating layer 127 are the same as or approximately the same as the height of the top surface of at least one of the first layer 112, the light-emitting layer 113, and the second layer 114. In addition, it is preferable that the top surface of the insulating layer 127 has a flat shape, and it may have a convex portion or a concave portion.

[0115] The insulating layer 125 has a region in contact with one or more side surfaces of the first layer 112, the light-emitting layer 113, and the second layer 114, and functions as a protective insulating layer for the first layer 112, the light-emitting layer 113, and the second layer 114. By providing the insulating layer 125, impurities (oxygen, moisture, and the like) can be prevented from entering the inside from the side surfaces of the first layer 112, the light-emitting layer 113, and the second layer 114, thereby providing a highly reliable display device.

[0116] If the width (thickness) of the insulating layer 125 in a region in contact with one or more side surfaces of the first layer 112, the light-emitting layer 113, and the second layer 114 in a cross-sectional view is large, the distance between the first layer 112, the light-emitting layer 113, and the second layer 114 increases, which may result in a low aperture ratio. Furthermore, if the width (thickness) of the insulating layer 125 is small, the effect of suppressing impurities from penetrating into the interior from the side surfaces of the first layer 112, the light-emitting layer 113, and / or the second layer 114 may be reduced. The width (thickness) of the insulating layer 125 in a region in contact with one or more side surfaces of the first layer 112, the light-emitting layer 113, and the second layer 114 is preferably 3 nm to 200 nm, more preferably 3 nm to 150 nm, further preferably 5 nm to 150 nm, further preferably 5 nm to 100 nm, further preferably 10 nm to 100 nm, and further preferably 10 nm to 50 nm. By setting the width (thickness) of the insulating layer 125 in the above-described range, a display device having a high aperture ratio and high reliability can be obtained.

[0117] The insulating layer 125 can be an insulating layer containing an inorganic material. For example, an inorganic insulating film such as an insulating oxide film, a nitride insulating film, an oxynitride insulating film, or a nitride oxide insulating film can be used for the insulating layer 125. The insulating layer 125 may have a single-layer structure or a stacked-layer structure. Examples of oxide insulating films 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 nitride insulating films include a silicon nitride film and an aluminum nitride film. Examples of oxynitride insulating films include a silicon oxynitride film and an aluminum oxynitride film. Examples of nitride oxide insulating films include a silicon nitride oxide film and an aluminum nitride oxide film. In particular, aluminum oxide is preferable because it has a high etching selectivity with respect to the EL layer and has a function of protecting the EL layer in the formation of the insulating layer 127 described later. In particular, by using an inorganic insulating film such as an aluminum oxide film, a hafnium oxide film, or a silicon oxide film formed by the ALD method as the insulating layer 125, it is possible to form an insulating layer 125 with few pinholes and excellent function of protecting the EL layer.

[0118] Note that in this specification and the like, an oxynitride insulator refers to a material whose composition contains more oxygen than nitrogen, and a nitride oxide insulator refers to a material whose composition contains more nitrogen than oxygen. For example, silicon oxynitride refers to a material whose composition contains more oxygen than nitrogen, and silicon nitride oxide refers to a material whose composition contains more nitrogen than oxygen.

[0119] The insulating layer 125 can be formed by a sputtering method, a CVD method, a PLD method, an ALD method, or the like. The insulating layer 125 is preferably formed by an ALD method because it has good coverage.

[0120] The insulating layer 127 provided on the insulating layer 125 has the function of planarizing recesses formed in the insulating layer 125 between adjacent light-emitting devices. In other words, the insulating layer 127 improves the flatness of the surface on which the common electrode 116 is formed. An insulating layer containing an organic material can be suitably used as the insulating layer 127. For example, acrylic resin, polyimide resin, epoxy resin, imide resin, polyamide resin, polyimideamide resin, silicone resin, siloxane resin, benzocyclobutene-based resin, phenolic resin, and precursors of these resins can be used as the insulating layer 127. Alternatively, organic materials such as polyvinyl alcohol (PVA), polyvinyl butyral, polyvinylpyrrolidone, polyethylene glycol, polyglycerin, pullulan, water-soluble cellulose, or alcohol-soluble polyamide resin can be used as the insulating layer 127. Alternatively, a photosensitive resin can be used as the photosensitive resin. A photoresist can be used as the photosensitive resin. The photosensitive resin can be a positive-type material or a negative-type material.

[0121] The difference in height between the upper surface of the insulating layer 127 and the upper surface of the second layer 114 is, for example, preferably 0.5 times or less, and more preferably 0.3 times or less, the thickness of the insulating layer 127. Alternatively, for example, the insulating layer 127 may be provided so that the upper surface of the second layer 114 is higher than the upper surface of the insulating layer 127. Alternatively, for example, the insulating layer 127 may be provided so that the upper surface of the insulating layer 127 is lower than the upper surface of the second layer 114.

[0122] It is preferable that the light emitting devices 130a, 130b, and 130c have a protective layer 131. By providing the protective layer 131, the reliability of the light emitting devices can be improved.

[0123] 1B, the protective layer 131 is illustrated as a single layer, but the protective layer 131 may be composed of multiple layers, such as a two-layer structure of an inorganic layer and an inorganic layer, a two-layer structure of an inorganic layer and an organic layer, or a three-layer structure of an inorganic layer, an organic layer, and an inorganic layer.

[0124] There is no restriction on the conductivity of the protective layer 131. The protective layer 131 can be made of at least one of an insulating film, a semiconductor film, and a conductive film.

[0125] The protective layer 131 has an inorganic film, which prevents oxidation of the common electrode 116 and prevents impurities (moisture, oxygen, etc.) from entering the light-emitting devices 130a, 130b, and 130c, thereby suppressing deterioration of the light-emitting devices and improving the reliability of the display device.

[0126] The protective layer 131 can be made of an inorganic insulating film such as an insulating oxide film, a nitride insulating film, an oxynitride insulating film, or a nitride oxide insulating film. Examples of oxide insulating films include a silicon oxide film, an aluminum 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 nitride insulating films include a silicon nitride film and an aluminum nitride film. Examples of oxynitride insulating films include a silicon oxynitride film and an aluminum oxynitride film. Examples of nitride oxide insulating films include a silicon nitride oxide film and an aluminum nitride oxide film.

[0127] The protective layer 131 preferably includes an insulating nitride film or an insulating nitride oxide film, and more preferably includes an insulating nitride film.

[0128] Alternatively, 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 be used for the protective layer 131. The inorganic film preferably has high resistance, specifically, preferably has higher resistance than the common electrode 116. The inorganic film may further contain nitrogen.

[0129] When light emitted from the light-emitting device is extracted through the protective layer 131, it is preferable that the protective layer 131 has high transparency to visible light. For example, ITO, IGZO, and aluminum oxide are preferable because they are inorganic materials that have high transparency to visible light.

[0130] For example, a stacked structure of an aluminum oxide film and a silicon nitride film on the aluminum oxide film, or a stacked structure of an aluminum oxide film and an IGZO film on the aluminum oxide film can be used as the protective layer 131. By using such a stacked structure, impurities (water, oxygen, etc.) can be prevented from entering the EL layer side.

[0131] 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.

[0132] The protective layer 131 may be formed using a plurality of different film formation methods. Specifically, the first layer of the protective layer 131 may be formed using atomic layer deposition, and the second layer of the protective layer 131 may be formed using sputtering.

[0133] Although not shown, a light-shielding layer may be provided at a position overlapping the insulating layer between pixels. Various optical components may be disposed at a position overlapping the light-emitting device. Examples of optical components include a polarizing plate, a retardation plate, a light diffusion layer (such as a diffusion film), an anti-reflection layer, and a light-collecting film. The exterior of the display device may also be provided with an antistatic film that prevents dust from adhering, a water-repellent film that makes it difficult for dirt to adhere, a hard coat film that prevents scratches from occurring during use, an impact-absorbing layer, and the like.

[0134] Furthermore, a substrate may be provided on the protective layer 131 via a resin layer. The substrate may be made of glass, quartz, ceramic, sapphire, resin, metal, alloy, semiconductor, or the like. A light-transmitting material is used for the substrate on the side from which light from the light-emitting device is extracted. The flexibility of the display device can be increased by using a flexible material for the substrate. A polarizing plate may also be used as the substrate.

[0135] The substrate may be made of polyester resin such as polyethylene terephthalate (PET) or polyethylene naphthalate (PEN), polyacrylonitrile resin, acrylic resin, polyimide resin, polymethyl methacrylate resin, polycarbonate (PC) resin, polyethersulfone (PES) resin, polyamide resin (nylon, aramid, etc.), polysiloxane resin, cycloolefin resin, polystyrene resin, polyamideimide resin, polyurethane resin, polyvinyl chloride resin, polyvinylidene chloride resin, polypropylene resin, polytetrafluoroethylene (PTFE) resin, ABS resin, cellulose nanofiber, etc. Glass having a thickness sufficient to provide flexibility may also be used for the substrate.

[0136] When a circularly polarizing plate is superimposed on a display device, it is preferable that the display device has a substrate with high optical isotropy. A substrate with high optical isotropy has small birefringence (or a small amount of birefringence).

[0137] The absolute value of the retardation (phase difference) of a substrate having high optical isotropy is preferably 30 nm or less, more preferably 20 nm or less, and even more preferably 10 nm or less.

[0138] Examples of films with high optical isotropy include triacetyl cellulose (TAC, also known as cellulose triacetate) films, cycloolefin polymer (COP) films, cycloolefin copolymer (COC) films, and acrylic films.

[0139] Furthermore, when a film is used as a substrate, the film may absorb water, causing deformation such as wrinkles in the display panel. Therefore, it is preferable to use a film with low water absorption for the substrate. For example, it is preferable to use a film with a water absorption rate of 1% or less, more preferably 0.1% or less, and even more preferably 0.01% or less.

[0140] The resin layer may be formed using various curable adhesives, such as photo-curable adhesives (e.g., ultraviolet curable), reactive curable adhesives, thermosetting adhesives, and anaerobic adhesives. Examples of such adhesives include epoxy resins, acrylic resins, silicone resins, phenolic resins, polyimide resins, imide resins, PVC (polyvinyl chloride) resins, PVB (polyvinyl butyral) resins, and EVA (ethylene vinyl acetate) resins. Materials with low moisture permeability, such as epoxy resins, are particularly preferred. Two-component resins may also be used. Adhesive sheets, etc., may also be used.

[0141] Materials that can be used for conductive layers such as the gate, source, and drain of a transistor, as well as various wirings and electrodes that constitute a display device include metals such as aluminum, titanium, chromium, nickel, copper, yttrium, zirconium, molybdenum, silver, tantalum, and tungsten, and alloys containing these metals as main components, etc. Films containing these materials can be used as a single layer or a stacked layer structure.

[0142] Examples of light-transmitting conductive materials include conductive oxides such as indium oxide, indium tin oxide, indium zinc oxide, zinc oxide, and zinc oxide containing gallium, or graphene. Alternatively, metal materials such as gold, silver, platinum, magnesium, nickel, tungsten, chromium, molybdenum, iron, cobalt, copper, palladium, and titanium, or alloy materials containing such metal materials, can be used. Alternatively, nitrides of such metal materials (e.g., titanium nitride) can be used. When using metal materials or alloy materials (or their nitrides), it is preferable to thin them sufficiently to ensure light-transmitting properties. A stacked film of the above materials can also be used as the conductive layer. For example, a stacked film of an alloy of silver and magnesium and indium tin oxide is preferable because it can enhance conductivity. These materials can also be used for conductive layers such as various wirings and electrodes constituting display devices, and conductive layers (conductive layers functioning as pixel electrodes or common electrodes) in light-emitting devices.

[0143] Examples of insulating materials that can be used for each insulating layer include resins such as acrylic resin and epoxy resin, and inorganic insulating materials such as silicon oxide, silicon oxynitride, silicon nitride oxide, silicon nitride, and aluminum oxide.

[0144] Next, details of the cross-sectional shape of the display device 100 and modified examples will be described with reference to Figures 2 to 5. Figures 2 to 5 enlarge the area 105 surrounded by the dashed line in Figure 1B and show the detailed structure and modified examples.

[0145] 2A is an enlarged view of region 105 in FIG. 1B . In the structural schematic diagram shown in FIG. 2A , the pixel electrode 111 (111b, 111c) has a region in contact with the first layer 112 and a region in contact with the insulating layer 125 on its side surface. The pixel electrode 111 (111b, 111c) may also have a region in contact with the light-emitting layer 113 (113b, 113c) and / or a region in contact with the second layer 114 on its side surface. Between adjacent pixel electrodes, organic layers 112G, 113bG, 113cG, and 114G are provided. Between adjacent pixel electrodes, the first layer 112, the light-emitting layer 113 (113b, 113c), and the second layer 114 each have a region covered with the insulating layer 125. Furthermore, an insulating layer 127 is provided on the insulating layer 125 between adjacent pixel electrodes. The insulating layer 127 is preferably provided so as to fill the recess between adjacent pixel electrodes. Furthermore, as shown in FIG. 2A , the insulating layer 127 may have a curved convex portion between adjacent pixel electrodes, and the end of the insulating layer 125 may have a forward tapered shape. In this way, when the insulating layer 127 has a curved convex portion and the insulating layer 125 has a forward tapered end, the coverage of the third layer 115 and the common electrode 116 can be improved. Therefore, poor connection due to a step in the common electrode 116 can be suppressed. Alternatively, an increase in electrical resistance due to a localized thinning of the common electrode 116 due to the step can be suppressed. While FIG. 2A shows an example in which the top surface of the insulating layer 127 has an arc-shaped convex portion in cross section, as shown in FIG. 2B , a portion of the top surface of the insulating layer 127 may have a concave shape.

[0146] 2A shows a configuration in which the insulating layer 125 is provided, but the present invention is not limited to this. FIG. 2C shows a modified example of the structure shown in FIG. 2A. As one embodiment of the present invention, a configuration in which the insulating layer 125 is not provided may be used, as shown in FIG. 2C. In the structure shown in FIG. 2C, the insulating layer 127 is preferably made of an organic material that causes little damage to the first layer 112, the light-emitting layer 113, and the second layer 114. For example, the insulating layer 127 is preferably made of an organic material such as polyvinyl alcohol (PVA), polyvinyl butyral, polyvinylpyrrolidone, polyethylene glycol, polyglycerin, pullulan, water-soluble cellulose, or an alcohol-soluble polyamide resin.

[0147] The shape of the insulating layer 127 of one embodiment of the present invention will be described using the width W1 of the first portion and the width W2 of the second portion indicated by a double arrow in FIG. 2C . The insulating layer 127 has a first portion located between a pair of pixel electrodes and a second portion located between a pair of EL layers, and the width W2 of the second portion can be said to be narrower than the width W1 of the first portion. Although the width W1 of the first portion and the width W2 of the second portion are not shown in FIGS. 2A , 2B , 3A to 3C , 4A to 4C , 5A , and 5B , the insulating layer 127 can be said to have a first portion located between a pair of pixel electrodes and a second portion located between a pair of EL layers, and the width W2 of the second portion can be said to be narrower than the width W1 of the first portion, as in FIG. 2C . Note that an insulating layer 127 whose width W2 of the second portion is narrower than the width W1 of the first portion is also referred to as having a constricted shape in a cross-sectional view.

[0148] 2A and other figures show a configuration in which the upper surfaces of insulating layer 125 and insulating layer 127 are higher than the upper surface of second layer 114, but the present invention is not limited to this. For example, as shown in Figures 3A and 3B, the upper surfaces of insulating layer 125 and insulating layer 127 may be configured to be approximately flush with the upper surfaces of first layer 112, light-emitting layer 113, and at least one of second layer 114.

[0149] 2A and the like shows an example of a structure in which the layer 101 is removed between adjacent pixel electrodes 111 (a structure in which the layer 101 has a recess between adjacent pixel electrodes 111), but the present invention is not limited to this, and may also have a structure in which the layer 101 is not removed between adjacent pixel electrodes 111 (a structure in which the layer 101 does not have a recess between adjacent pixel electrodes 111, or a structure in which the layer 101 is flat between adjacent pixel electrodes 111). Note that a structure in which the layer 101 is removed between adjacent pixel electrodes 111 can also be referred to as a structure in which the layer 101 has a step between the adjacent pixel electrodes 111, and this step is referred to as a step portion of the layer 101.

[0150] As shown in FIG. 3C , the insulating layer 127 may have a recess that is lower than the height of the top surface of at least one of the first layer 112, the light-emitting layer 113, and the second layer 114, but it is desirable that the third layer 115 and the common electrode 116 are not interrupted at the recess.

[0151] As described above, it is preferable that the side surface of the pixel electrode 111 has a region where the first layer 112 is not formed, but the effect of electrically isolating the light-emitting layers of each pixel may also be obtained by making the first layer 112 thin on the side surface of the pixel electrode 111. Therefore, it is not necessarily required that the side surface of the pixel electrode 111 has a region where the first layer 112 is not formed.

[0152] Modified examples of the structure of the region 105 in such a case are shown in FIGS. 4A and 4B . FIG. 4A illustrates an example of a modification of the structure of FIG. 2A , in which the first layer 112 is thinly formed on the side surface of the pixel electrode 111. FIG. 4B also illustrates the structure of the region 105 in FIG. 1B , in which not only the first layer 112 is thinly formed on the side surface of the pixel electrode 111, but also the light-emitting layer 113 (the second light-emitting layer 113b and the third light-emitting layer 113c) is thinly formed, and the second light-emitting layer 113b and the third light-emitting layer 113c overlap on the organic layer 112G. In the display device of one embodiment of the present invention, the first layer 112 is discontinuous or thin between adjacent pixel electrodes. Therefore, even if there is a region where the second light-emitting layer 113b and the third light-emitting layer 113c overlap each other as shown in FIG. 4B , crosstalk between adjacent pixels is suppressed.

[0153] 4C is a modified example of the structure shown in Fig. 2A. As shown in Fig. 4C, the end of the insulating layer 125 may have a structure (also called an eave structure) that protrudes beyond the insulating layer 127. The curved upper surface of the insulating layer 127 smoothly connects to the upper surface of the insulating layer 125, thereby improving the coverage of the third layer 115 and / or the common electrode 116.

[0154] 5A and 5B are modifications of the structure shown in Fig. 2A. As shown in Fig. 5A, a structure having an insulating layer 118 between adjacent pixel electrodes 111 may be used.

[0155] 5A , when the side surfaces of the pixel electrodes 111 (111b, 111c) are covered with the insulating layer 118, the pixel electrodes 111 (111b, 111c) can be prevented from contacting the light-emitting layers 113 (113b, 113c). Also, the pixel electrodes 111 (111b, 111c) can be prevented from contacting the second layer 114.

[0156] 5B , when the side surfaces of the pixel electrodes 111 (111b, 111c) and the first layer 112 are covered with the insulating layer 118, the pixel electrodes 111 (111b, 111c) and the light-emitting layers 113 (113b, 113c) can be prevented from contacting each other. Also, the pixel electrodes 111 (111b, 111c) and the second layer 114 can be prevented from contacting each other. Also, the first layer 112 and the second layer 114 can be prevented from contacting each other.

[0157] Next, a structure of a display device according to one embodiment of the present invention in which the first layer 112 is formed by separation in a self-aligned manner will be described with reference to FIGS.

[0158] 6A and 6B are schematic cross-sectional views showing an example of an end structure of the pixel electrode 111. For the sake of explanation, only the layer 101, the pixel electrode 111, and the first layer 112 are shown here. Note that the details of the layer 101 are not shown.

[0159] In a manufacturing method of a display device according to one embodiment of the present invention, a conductive layer is formed over the entire surface, and then a resist mask is formed in a position corresponding to each pixel. The conductive layer is then processed into an island shape to form a pixel electrode 111. In Fig. 6A , the angle between the side surface of the pixel electrode 111 and the bottom surface of the pixel electrode 111 is a taper angle θ, and the thickness of the pixel electrode 111 is Ta. In the example of Fig. 6A , no step portion is formed in the layer 101, so the height difference T1 between the top surface of the layer 101 and the pixel electrode 111 is equal to Ta.

[0160] Next, the first layer 112 is formed over the entire surface. Here, when T1 / T2 is 0.5 or more, preferably 0.8 or more, more preferably 1 or more, and even more preferably 1.5 or more, where T2 is the thickness of the first layer 112, and θ is 60 degrees or more and 140 degrees or less, preferably 70 degrees or more and 140 degrees or less, and even more preferably 80 degrees or more and 140 degrees or less, a region where the first layer 112 is not formed can be obtained on the side surface of the pixel electrode 111. In this case, the first layer 112 is separated into islands at the same position as the pixel electrode 111, and therefore the first layer 112, the light-emitting layer 113, and the second layer 114 can be formed in a self-aligned manner.

[0161] FIG. 6B is a modified example of FIG. 6A and illustrates a structure in which the layer 101 has a step portion between adjacent pixel electrodes 111. As shown in FIG. 6B , the sum of the depth Tb of the step portion of the layer 101 and the film thickness Ta of the pixel electrode 111 is the step height T1 (T1 = Ta + Tb) between adjacent pixel electrodes 111. In FIG. 6B , the angle formed by the bottom extension line BS' extending from the bottom surface BS of the step portion of the layer 101 and the side surface of the step portion of the layer 101 is the taper angle θ. Note that if the bottom surface BS of the step portion of the layer 101 and the bottom surface of the pixel electrode 111 are not parallel, the bottom extension line BS' can be an extension line extending parallel to the pixel electrode from the bottom of the step portion of the layer 101 to below the pixel electrode 111. Similarly, even if the bottom of the step portion of the layer 101 is curved rather than flat, the bottom stretched line BS' can be defined as an extension line extending from the lowest part of the step portion of the layer 101 to below the pixel electrode 111, parallel to the pixel electrode. Therefore, the step height T1 can also be considered the shortest distance from the bottom stretched line BS' to the top surface of the first electrode. Here, when the film thickness of the first layer 112 is T2, T1 / T2 is 0.5 or more, preferably 0.8 or more, more preferably 1 or more, and even more preferably 1.5 or more, and θ is 60 degrees or more and 140 degrees or less, preferably 70 degrees or more and 140 degrees or less, and even more preferably 80 degrees or more and 140 degrees or less, a region where the first layer 112 is not formed can be obtained on the side surface of the pixel electrode 111. Therefore, as shown in FIG. 6B , a structure in which the layer 101 is scraped between adjacent pixel electrodes 111 makes it easier to create a step in the first layer 112.

[0162] As an example of a structure in which the layer 101 has a step portion between adjacent pixel electrodes 111, FIG. 6B shows a case in which the side surface of the step portion of the layer 101 and the side surface of the pixel electrode 111 have the same taper angle and are straight in a cross-sectional view. The structure of the display device of one embodiment of the present invention is not limited to the above, and the taper angle of the side surface of the step portion of the layer 101 may not match the taper angle of the side surface of the pixel electrode 111. Furthermore, the side surface of the step portion of the layer 101 and / or the side surface of the pixel electrode 111 may have multiple surfaces or may have a curved surface. As an example of such a structure, schematic cross-sectional views of the pixel electrode 111 and the layer 101 are shown in FIGS. 7A to 7F .

[0163] 7A and 7B are diagrams showing an example in which the taper angle θa of the side surface of the pixel electrode 111 does not match the taper angle θb of the side surface of the step portion of the layer 101. Also, FIGS. 7C and 7D are diagrams showing an example in which the side surface of the pixel electrode 111 has multiple surfaces. Also, FIG. 7E is a diagram showing an example in which the side surface of the pixel electrode 111 has a curved surface. Also, FIG. 7F is a diagram showing an example in which a portion of the side surface of the pixel electrode 111 has a recessed structure. As described above, in order to separate the first layer 112 into islands in a self-aligned manner, the height of the step from the bottom surface of the step portion of the layer 101 to the top surface of the pixel electrode 111, the taper angle of the side surface of the step, and the film thickness of the first layer 112 need to be formed within predetermined ranges.

[0164] Here, the effective step height ET for separating the first layer 112 into islands in a self-aligned manner will be considered. Although not shown in FIGS. 7A to 7F , the film thickness of the first layer 112 is T2. When the step portion of the layer 101 and the pixel electrode 111 are divided into multiple regions based on differences in taper angle, for example, in FIGS. 7A and 7B , region a has a height of Ta and a taper angle of θa, and region b has a height of Tb and a taper angle of θb. Here, when the total height of the regions having a taper angle of 60 degrees or more and 140 degrees or less is defined as the effective step height ET, when ET / T2 is 0.5 or more, preferably 0.8 or more, more preferably 1 or more, and even more preferably 1.5 or more, a region where the first layer 112 is not formed can be obtained on the side surface of the pixel electrode 111 or the step portion of the layer 101.

[0165] For example, in Fig. 7A, θa in region a is less than 60 degrees, and θb in region b is 60 degrees or more and 140 degrees or less. Therefore, in the example shown in Fig. 7A, ET = Tb. Also, in Fig. 7B, θa in region a and θb in region b are both 60 degrees or more and 140 degrees or less. Therefore, in the example shown in Fig. 7B, ET = Ta + Tb.

[0166] In addition, in FIG. 7C , the pixel electrode 111 has regions a1 and a2, and the step portion of the layer 101 has region b. θa1 of region a1 is less than 60 degrees, and θa2 of region a2 and θb of region b are both 60 degrees or more and 140 degrees or less. Therefore, in the example shown in FIG. 7C , ET = Ta2 + Tb. In addition, in FIG. 7D , the pixel electrode 111 has regions a1 and a2, and the step portion of the layer 101 has region b. θa1 of region a1 and θb of region b are both 60 degrees or more and 140 degrees or less, and θa2 of region a2 is less than 60 degrees. Therefore, in the example shown in FIG. 7D , ET = Ta1 + Tb.

[0167] 7E , when the side surface of the pixel electrode 111 has a curved surface, the effective step height ET includes the region where the angle θs between the tangent line TL at the tangent point TP and a line parallel to the bottom surface of the pixel electrode 111 in a cross-sectional view of the curved surface is between 60 degrees and 140 degrees. When the side surface of the pixel electrode 111 has a curved surface as in the example shown in FIG. 7E , the curved surface is considered to be divided into a region a2 where the angle between the tangent line and the bottom surface of the pixel electrode 111 in a cross-sectional view is between 60 degrees and 140 degrees, and a region a1 where the angle between the tangent line and the bottom surface of the pixel electrode 111 is less than 60 degrees. In this case, the pixel electrode 111 in FIG. 7E has regions a1, a2, and a3. Since θs of the region a2, θa3 of the region a3, and θb of the region b are all between 60 degrees and 140 degrees, ET=Ta2+Ta3+Tb.

[0168] As described above, the taper angle (or tangent angle) of the region included in the effective step height ET is preferably 60 degrees or more and 140 degrees or less. A more preferred structure is 70 degrees or more and 140 degrees or less, and even more preferably 80 degrees or more and 140 degrees or less.

[0169] As another example of the pixel electrode 111 having a plurality of side surfaces, a structure in which a portion of the side surface is recessed may be used, as shown in FIG. 7F . In this case, the film thickness of the region where the recession distance RD is greater than 0 is included in the effective step height ET. In the example shown in FIG. 7F , θb of region b is between 60 degrees and 140 degrees, the recession distance RD of region Ta2 is greater than 0, and θa1 of region a1 is less than 60 degrees, so ET = Ta2 + Tb. Note that for regions where the recession distance RD is greater than 0, the height of the region can be included in the effective step height ET regardless of the taper angle of the region.

[0170] 7F can be formed, for example, by using a material with a fast etching rate for the lower conductive layer when fabricating the pixel electrode 111 consisting of two layers (first and second conductive layers) made of different materials. More specifically, the pixel electrode 111 can be fabricated by anisotropically etching the first conductive layer and the second conductive layer on the first conductive layer by dry etching or the like, and then selectively isotropically etching the first conductive layer by wet etching or the like.

[0171] Note that the region where the first layer 112 is not formed on the side surface of the pixel electrode 111 formed in an island shape as shown above or on the side surface of the step portion of the layer 101 is sometimes referred to as a step portion or step region. As described above, it is preferable to have a region where the first layer 112 is not formed on the side surface of the pixel electrode 111 or the side surface of the step portion of the layer 101, but the effect of electrically isolating the light-emitting layers of each pixel may also be obtained by making the first layer 112 thin on the side surface of the pixel electrode 111 or the side surface of the step portion of the layer 101. Therefore, it is not necessarily necessary to have a region where the first layer 112 is not formed on the side surface of the pixel electrode 111 or the side surface of the step portion of the layer 101.

[0172] [Pixel Layout] Next, pixel layouts different from that shown in FIG. 1A will be described. There are no particular limitations on the arrangement of sub-pixels, and various methods can be applied. Examples of sub-pixel arrangements include a stripe arrangement, an S-stripe arrangement, a matrix arrangement, a delta arrangement, a Bayer arrangement, and a pentile arrangement.

[0173] Examples of the top surface shape of the subpixel include a triangle, a quadrangle (including a rectangle and a square), a polygon such as a pentagon, a polygon with rounded corners, an ellipse, a circle, etc. Here, the top surface shape of the subpixel corresponds to the top surface shape of the light-emitting region of the light-emitting device.

[0174] An S-stripe arrangement is applied to the pixel 110 shown in Fig. 8A. The pixel 110 shown in Fig. 8A is composed of three subpixels: subpixels 110a, 110b, and 110c. For example, the subpixel 110a may be a blue subpixel B, the subpixel 110b may be a red subpixel R, and the subpixel 110c may be a green subpixel G.

[0175] The pixel 110 shown in FIG. 8B includes a subpixel 110a having a generally trapezoidal top surface shape with rounded corners, a subpixel 110b having a generally triangular top surface shape with rounded corners, and a subpixel 110c having a generally rectangular or hexagonal top surface shape with rounded corners. The subpixel 110a has a larger light-emitting area than the subpixel 110b. In this manner, the shape and size of each subpixel can be determined independently. For example, the subpixel having a more reliable light-emitting device can be made smaller in size. For example, the subpixel 110a may be a green subpixel G, the subpixel 110b may be a red subpixel R, and the subpixel 110c may be a blue subpixel B.

[0176] The pixels 124a and 124b shown in Fig. 8C are arranged in a Pentile arrangement. Fig. 8C shows an example in which a pixel 124a having subpixels 110a and 110b and a pixel 124b having subpixels 110b and 110c are arranged alternately. For example, the subpixel 110a may be a red subpixel R, the subpixel 110b may be a green subpixel G, and the subpixel 110c may be a blue subpixel B.

[0177] 8D and 8E are arranged in a delta configuration. The pixel 124a has two subpixels (subpixels 110a and 110b) in the top row (first row) and one subpixel (subpixel 110c) in the bottom row (second row). The pixel 124b has one subpixel (subpixel 110c) in the top row (first row) and two subpixels (subpixels 110a and 110b) in the bottom row (second row). For example, the subpixel 110a may be a red subpixel R, the subpixel 110b may be a green subpixel G, and the subpixel 110c may be a blue subpixel B.

[0178] FIG. 8D shows an example in which each subpixel has a substantially rectangular top surface shape with rounded corners, and FIG. 8E shows an example in which each subpixel has a circular top surface shape.

[0179] 8F shows an example in which subpixels of each color are arranged in a zigzag pattern. Specifically, when viewed from above, the positions of the upper edges of two subpixels aligned in the column direction (e.g., subpixels 110a and 110b, or subpixels 110b and 110c) are misaligned. For example, the subpixel 110a may be a red subpixel R, the subpixel 110b may be a green subpixel G, and the subpixel 110c may be a blue subpixel B.

[0180] In photolithography, the finer the pattern to be processed, the more significant the effect of light diffraction becomes. This reduces the fidelity of the photomask pattern when it is transferred by exposure, making it difficult to process the resist mask into the desired shape. Therefore, even if the photomask pattern is rectangular, it is likely to have rounded corners. As a result, the top surface shape of the subpixel may become a polygon with rounded corners, an ellipse, a circle, or the like.

[0181] The display device according to one embodiment of the present invention may include a light-receiving device in a pixel.

[0182] [Example of manufacturing method of display device] Next, an example of a manufacturing method of a display device will be described with reference to Figures 9A to 14C. Figures 9A and 9B are top views showing a manufacturing method of a display device. Figures 10A to 10C show cross-sectional views taken along dashed lines X1-X2 and Y1-Y2 in Figure 1A side by side. Figures 11A to 14C are similar to Figure 10.

[0183] Thin films (insulating films, semiconductor films, conductive films, etc.) constituting display devices can be formed using a sputtering method, a chemical vapor deposition method, a vacuum evaporation method, a pulsed laser deposition (PLD) method, an ALD method, etc. CVD methods include a PECVD method and a thermal CVD method. One type of thermal CVD method is a metal organic chemical vapor deposition (MOCVD) method.

[0184] Furthermore, thin films (insulating films, semiconductor films, conductive films, etc.) constituting the display device can be formed by methods such as spin coating, dipping, spray coating, inkjet, dispensing, screen printing, offset printing, doctor knife, slit coating, roll coating, curtain coating, and knife coating.

[0185] In particular, vacuum processes such as vapor deposition and solution processes such as spin coating and inkjet printing can be used to fabricate light-emitting devices. Vapor deposition methods include physical vapor deposition (PVD) methods such as sputtering, ion plating, ion beam deposition, molecular beam deposition, and vacuum deposition, and chemical vapor deposition (CVD). In particular, functional layers included in the EL layer (hole injection layer, hole transport layer, light-emitting layer, electron transport layer, electron injection layer, hole blocking layer, electron blocking layer, etc.) can be formed by vapor deposition (vacuum deposition, etc.), coating methods (dip coating, die coating, bar coating, spin coating, spray coating, etc.), printing methods (inkjet printing, screen (stencil printing), offset (lithographic printing), flexography (relief printing), gravure, microcontact printing, etc.), etc.

[0186] Furthermore, when processing the thin film that constitutes the display device, it can be processed using a photolithography method or the like. Alternatively, the thin film may be processed using a nanoimprint method, a sandblasting method, a lift-off method or the like. Furthermore, the island-shaped thin film may be directly formed by a film formation method using a shielding mask such as a metal mask.

[0187] There are two typical photolithography methods: one is to form a resist mask on the thin film to be processed, process the thin film by etching or the like, and then remove the resist mask; the other is to form a photosensitive thin film, and then process the thin film into the desired shape by exposure and development.

[0188] In photolithography, the light used for exposure can be, for example, i-line (wavelength 365 nm), g-line (wavelength 436 nm), h-line (wavelength 405 nm), or a mixture of these. Other light sources that can be used include ultraviolet light, KrF laser light, ArF laser light, etc. Exposure can also be performed by immersion exposure technology. Extreme ultraviolet light (EUV) or X-rays can also be used as the light used for exposure. An electron beam can also be used instead of the light used for exposure. Extreme ultraviolet light, X-rays, or an electron beam are preferred because they enable extremely fine processing. When exposure is performed by scanning a beam such as an electron beam, a photomask is not required.

[0189] For etching the thin film, dry etching, wet etching, sandblasting, or the like can be used.

[0190] First, as shown in FIG. 10A, a conductive film 111A is formed over a layer 101 including a transistor.

[0191] The conductive film 111A is a layer that will be processed later to become the pixel electrodes 111a, 111b, and 111c and the conductive layer 123. Therefore, the structure applicable to the pixel electrodes described above can be applied to the conductive film 111A. The conductive film 111A can be formed by, for example, sputtering or vacuum deposition.

[0192] 10B, a resist mask 190a is formed over the conductive film 111A. The resist mask can be formed by applying a photosensitive resin (photoresist) and then performing exposure and development.

[0193] The resist mask may be made of either a positive resist material or a negative resist material.

[0194] 9A , the resist mask 190a is provided at a position overlapping the region that will later become the subpixel 110a, the region that will later become the subpixel 110b, and the region that will later become the subpixel 110c. It is preferable that the resist mask 190a has an island-shaped pattern for each subpixel 110a, 110b, or 110c. Alternatively, the resist mask 190a may have a strip-shaped pattern for multiple subpixels 110a, 110b, or 110c that are aligned in a line (aligned in the Y direction in FIG. 9A ).

[0195] It is preferable that the resist mask 190 a is also provided at a position that overlaps with the region that will later become the connection portion 140 .

[0196] 10C , a resist mask 190a is used to remove a portion of the conductive film 111A to form the pixel electrodes 111a, 111b, and 111c and the connection portion 140. At this time, the insulating layer of the layer 101 may be processed in the same pattern as the pixel electrodes, so that the layer 101 has a recessed portion between adjacent pixel electrodes.

[0197] The conductive film 111A can be processed by wet etching or dry etching, and is preferably processed by anisotropic etching.

[0198] 11A, the resist mask 190a is removed. For example, the resist mask 190a can be removed by ashing using oxygen plasma. Alternatively, the resist mask 190a may be removed by a wet process.

[0199] Next, the first layer 112 is formed. The first layer 112 may comprise a hole injection layer and a hole transport layer. Alternatively, the first layer 112 may comprise only a hole injection layer. Here, the angle between the side surface of the pixel electrode 111 and the bottom surface of the pixel electrode 111 is the taper angle θ, the thickness of the pixel electrode 111 is T1, and the thickness of the first layer 112 is T2. When the shapes of the pixel electrode 111 and the first layer 112 satisfy the following conditions: T1 / T2 is 0.5 or more, preferably 0.8 or more, more preferably 1 or more, and even more preferably 1.5 or more; and θ is 60 degrees or more and 140 degrees or less, preferably 70 degrees or more and 140 degrees or less, and even more preferably 80 degrees or more and 140 degrees or less, the first layer 112 having the hole injection layer can be formed in an island-like manner, as shown in FIG. 11B . At this time, an organic layer 112G is formed on the layer 101 between adjacent pixel electrodes. The first layer 112 can be formed by a method such as vapor deposition (including vacuum deposition), sputtering, printing, inkjet printing, or coating. The first layer 112 is preferably formed by a vapor deposition method. A premix material may be used in film formation using a vapor deposition method. Note that in this specification and the like, a premix material is a composite material in which multiple materials are blended or mixed in advance.

[0200] 11B , in the cross-sectional view between Y1 and Y2, the first layer 112 is located inside the connecting portion 140. For example, by using a mask for defining the deposition area (also called an area mask or a rough metal mask to distinguish it from a fine metal mask), it is possible to change the region where the first layer 112 is deposited. By combining it with the area mask as described above, it is possible to fabricate a light-emitting device using a relatively simple process.

[0201] 11C , a first light-emitting layer 113a having a light-emitting layer that emits red light is formed. The first light-emitting layer 113a can be formed by a method similar to that for the first layer 112, and is preferably formed by an evaporation method. In the manufacturing method of one embodiment of the present invention, the first light-emitting layer 113a is preferably formed as an island-shaped first light-emitting layer 113a by a vacuum evaporation method using a metal mask (also referred to as a shadow mask). At this time, an organic layer 113aG is formed on the organic layer 112G between adjacent pixel electrodes.

[0202] 12A , a second light-emitting layer 113b having a light-emitting layer that emits green light is formed. The second light-emitting layer 113b can be formed by a method similar to that for the first layer 112, and is preferably formed by an evaporation method. In the manufacturing method of one embodiment of the present invention, the second light-emitting layer 113b is preferably formed as an island-shaped second light-emitting layer 113b by a vacuum evaporation method using a metal mask (also referred to as a shadow mask). At this time, an organic layer 113bG is formed on the organic layer 112G between adjacent pixel electrodes.

[0203] 12B , a third light-emitting layer 113c having a light-emitting layer that emits blue light is formed. The third light-emitting layer 113c can be formed by a method similar to that of the first layer 112, and is preferably formed by an evaporation method. In the manufacturing method of one embodiment of the present invention, the third light-emitting layer 113c is preferably formed as an island-shaped third light-emitting layer 113c by a vacuum evaporation method using a metal mask (also referred to as a shadow mask). At this time, an organic layer 113cG is formed on the organic layer 112G between adjacent pixel electrodes.

[0204] 11C, 12A, and 12B, a hole transport layer may be formed below each light-emitting layer as part of the light-emitting layer 113. Also, when forming the light-emitting layer 113 shown in FIG. 11C, 12A, and 12B, an electron transport layer may be formed above each light-emitting layer as part of the light-emitting layer 113.

[0205] In the above description, the light-emitting layers are formed in the order of red, green, and blue light emission, but the order of formation of red, green, and blue is not limited to the method for manufacturing a display device according to one embodiment of the present invention. For example, the light-emitting layers may be formed in the order of red, blue, green, green, green, green, blue, blue, blue, blue, red, blue, red, green, or blue, green, red.

[0206] Next, as shown in FIG. 12C , the second layer 114 is formed. The second layer 114 can be an electron transport layer. The second layer 114 can be formed by a method similar to that of the first layer 112, preferably by vapor deposition. Similarly to the first layer 112, the second layer 114 is located inside the connection portion 140 in the cross-sectional view between Y1 and Y2. For example, the region where the second layer 114 is formed can be changed by using a mask (also called an area mask or a rough metal mask, to distinguish it from a fine metal mask) for defining the film formation area. At this time, an organic layer 114G is formed on the organic layer 112G between adjacent pixel electrodes. Note that one or two of the organic layers 113aG, 113bG, and 113cG may be present between the organic layer 112G and the organic layer 114G.

[0207] Next, as shown in FIG. 13A, an insulating film 125A is formed to cover the pixel electrodes 111a, 111b, and 111c, the conductive layer 123, the first layer 112, the first light-emitting layer 113a, the second light-emitting layer 113b, the third light-emitting layer 113c, and the second layer 114.

[0208] The insulating film 125A can be, for example, an inorganic insulating film such as an insulating oxide film, a nitride insulating film, an oxynitride insulating film, or a nitride oxide insulating film. Examples of oxide insulating films include a silicon oxide film, an aluminum oxide film, a magnesium oxide film, a gallium oxide film, a germanium oxide film, a 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 nitride insulating films include a silicon nitride film and an aluminum nitride film. Examples of oxynitride insulating films include a silicon oxynitride film and an aluminum oxynitride film. Examples of nitride oxide insulating films include a silicon nitride oxide film and an aluminum nitride oxide film. Metal oxide films such as an indium gallium zinc oxide film may also be used.

[0209] The insulating film 125A preferably functions as a barrier insulating film against at least one of water and oxygen, or has a function of suppressing diffusion of at least one of water and oxygen, or has a function of capturing or fixing (also referred to as gettering) at least one of water and oxygen.

[0210] In this specification and the like, a barrier insulating film refers to an insulating film having barrier properties. Furthermore, in this specification and the like, the term "barrier properties" refers to a function of suppressing the diffusion of a corresponding substance (also referred to as low permeability), or a function of capturing or fixing a corresponding substance (also referred to as gettering).

[0211] The insulating film 125A has the above-mentioned barrier insulating film function or gettering function, which makes it possible to suppress the intrusion of impurities (typically water or oxygen) that can diffuse into each light-emitting device from the outside. With this configuration, it is possible to provide a display device with excellent reliability.

[0212] Next, as shown in FIG. 13B, an insulating film 127A is formed on the insulating film 125A.

[0213] The insulating film 127A can be made of an organic material. Examples of organic materials include acrylic resin, polyimide resin, epoxy resin, imide resin, polyamide resin, polyimideamide resin, silicone resin, siloxane resin, benzocyclobutene-based resin, phenolic resin, and precursors of these resins. The insulating film 127A can also be made of an organic material such as polyvinyl alcohol (PVA), polyvinyl butyral, polyvinylpyrrolidone, polyethylene glycol, polyglycerin, pullulan, water-soluble cellulose, or alcohol-soluble polyamide resin. The insulating film 127A can also be made of a photosensitive resin. A photoresist can be used as the photosensitive resin. The photosensitive resin can be a positive-type material or a negative-type material.

[0214] The method for forming the insulating film 127A is not particularly limited, and the insulating film 127A can be formed using a wet film formation method such as spin coating, dipping, spray coating, inkjet printing, dispensing, screen printing, offset printing, doctor knife method, slit coating, roll coating, curtain coating, or knife coating. In particular, it is preferable to form the insulating film 127A by spin coating.

[0215] The insulating films 125A and 127A are preferably formed by a method that causes less damage to the EL layer (such as plasma damage or UV damage). In particular, since the insulating film 125A is formed in contact with the side surface of the EL layer, it is preferably formed by a method that causes less damage to the EL layer than the insulating film 127A. Furthermore, the insulating films 125A and 127A are each formed at a temperature lower than the heat resistance temperature of the EL layer (typically, 200° C. or lower, preferably 100° C. or lower, and more preferably 80° C. or lower). For example, an aluminum oxide film can be formed as the insulating film 125A by an ALD method. The ALD method is preferable because it can reduce damage to the EL layer and form a film with high coverage.

[0216] 13C, insulating film 127A is processed to form insulating layer 127. Insulating layer 127 is formed so as to contact the side surface of insulating film 125A and the upper surface of the recess.

[0217] For example, when a photosensitive resin is used for the insulating film 127A, the photosensitive resin is exposed to light and then developed to remove unnecessary photosensitive resin, thereby forming a pattern. Note that a heat treatment may be performed after development to make the top surface of the insulating layer 127 into a gently sloping convex shape.

[0218] Next, as shown in FIG. 14A , a portion of the insulating film 125A is removed to form an insulating layer 125. This exposes the second layer 114 on the pixel electrodes 111a, 111b, and 111c, and the conductive layer 123 at the connection portion 140. The insulating layer 125 (and further the insulating layer 127) are provided so as to cover the side surfaces of the pixel electrodes 111a, 111b, and 111c. This prevents a film (a film constituting an EL layer or a common electrode) to be formed later from coming into contact with the pixel electrodes 111a, 111b, and 111c, etc., and thus prevents the light-emitting device from shorting out. Furthermore, the insulating layer 125 and the insulating layer 127 are preferably provided so as to cover the side surfaces of the first layer 112, the light-emitting layer 113 (the first light-emitting layer 113a, the second light-emitting layer 113b, and the third light-emitting layer 113c), and the second layer 114. This prevents a film to be formed later from coming into contact with the side surfaces of these layers, thereby preventing the light-emitting device from shorting out. Furthermore, damage to the first layer 112, the light-emitting layer 113 (the first light-emitting layer 113 a, the second light-emitting layer 113 b, and the third light-emitting layer 113 c), and the second layer 114 in subsequent steps can be prevented.

[0219] In particular, if a recess is provided in a part of the layer 101 including the transistor (specifically, the insulating layer located on the outermost surface), it is possible to cover the entire side surfaces of the pixel electrodes 111a, 111b, and 111c with the insulating layer 125 and the insulating layer 127, which is preferable.

[0220] In addition, in the connection portion 140 , the insulating layer 125 (and further the insulating layer 127 ) is preferably provided so as to cover the side surfaces of the conductive layer 123 .

[0221] The height of the top surface of the insulating layer 125 and the height of the top surface of the insulating layer 127 are preferably the same as or approximately the same as the height of the top surface of the second layer 114. The top surface of the insulating layer 127 preferably has a flat shape, and may have a convex portion or a concave portion.

[0222] The insulating film 125A can be processed by wet etching, dry etching, etc. In particular, by using the wet etching method, damage to the second layer 114 can be reduced when removing the insulating layer 125 compared to when using the dry etching method.

[0223] Furthermore, the process of processing the insulating film 125A and the process of processing the insulating film 127A may be combined. By appropriately combining the process of processing the insulating film 125A and the process of processing the insulating film 127A, the insulating layer 125 and the insulating layer 127 can have various structures as shown in FIGS.

[0224] Alternatively, one or both of the insulating film 125A and the insulating film 127A may be removed by dissolving them in a solvent such as water or alcohol. Examples of alcohol include ethyl alcohol, methyl alcohol, isopropyl alcohol (IPA), and glycerin.

[0225] After the insulating layers 125 and 127 are formed, drying treatment may be performed to remove water contained in the EL layer and water adsorbed to the surface of the EL layer. For example, heat treatment can be performed in an inert gas atmosphere or a reduced-pressure atmosphere. The heat treatment can be performed at a substrate temperature of 50° C. to 200° C., preferably 60° C. to 150° C., and more preferably 70° C. to 120° C. A reduced-pressure atmosphere is preferable because drying can be performed at a lower temperature.

[0226] 14B, a third layer 115 is formed to cover the insulating layer 125, the insulating layer 127, and the second layer 114. As the third layer 115, an electron injection layer can be formed.

[0227] The materials that can be used for the third layer 115 are as described above. The third layer 115 can be formed by a method such as a vapor deposition method (including a vacuum deposition method), a transfer method, a printing method, an inkjet method, or a coating method. The third layer 115 may also be formed using a premixed material.

[0228] If the insulating layers 125 and 127 are not provided, the pixel electrode 111 and the third layer 115 may come into contact with each other. This contact may cause a short circuit in the light-emitting device, especially if the third layer 115 has high conductivity. However, in the display device of one embodiment of the present invention, the insulating layers 125 and 127 cover the side surfaces of the first layer 112, the light-emitting layer 113, the second layer 114, and the pixel electrodes 111a, 111b, and 111c. This prevents the highly conductive third layer 115 from coming into contact with these layers, thereby preventing a short circuit in the light-emitting device. This improves the reliability of the light-emitting device.

[0229] 14C , a common electrode 116 is formed on the third layer 115 and the conductive layer 123. As shown in Fig. 14C , the conductive layer 123 and the common electrode 116 are electrically connected. Note that Fig. 14B shows an example in which a mask (also referred to as an area mask or a rough metal mask to distinguish it from a fine metal mask) is used to define a film formation area when the third layer 115 is formed, as with the first layer 112. However, a structure in which the third layer 115 is formed over the entire surface and the conductive layer 123 and the common electrode 116 are electrically connected via the third layer 115 may also be used.

[0230] The materials that can be used for the common electrode 116 are as described above. The common electrode 116 can be formed by, for example, sputtering or vacuum deposition. Alternatively, a film formed by deposition and a film formed by sputtering may be stacked.

[0231] Thereafter, as shown in FIG. 14C, a protective layer 131 is formed on the common electrode 116 .

[0232] The materials and film formation methods that can be used for the protective layer 131 are as described above. Examples of film formation methods for the protective layer 131 include vacuum deposition, sputtering, CVD, and ALD. The protective layer 131 may have a single-layer structure or a multilayer structure. When the protective layer 131 has a multilayer structure, films formed using different film formation methods may be stacked.

[0233] Although an example is shown in which a mask (also referred to as an area mask, a rough metal mask, or the like) is used to define a deposition area when the third layer 115 and the common electrode 116 are formed, a mask for defining a deposition area may not be used. For example, when the mask is not used to form the common electrode 116, after the step shown in FIG. 13B , a resist mask 190b may be formed on the common electrode 116 as shown in FIG. 9B , a processing step of the common electrode 116 may be performed, and then the step of forming the protective layer 131 may be performed.

[0234] A display device according to one embodiment of the present invention includes an insulating layer covering each side surface of a pixel electrode, a light-emitting layer, and a carrier transport layer. In a manufacturing process of the display device, the carrier transport layer can be formed in a self-aligned and separated manner, so that the display device has a structure in which crosstalk is reduced. Furthermore, the insulating layer prevents contact between the pixel electrode and the carrier injection layer or the common electrode, thereby preventing short circuits in the light-emitting device.

[0235] This embodiment mode can be combined with other embodiment modes as appropriate. In addition, in this specification, when a plurality of configuration examples are shown in one embodiment mode, the configuration examples can be combined as appropriate.

[0236] Embodiment 2 In this embodiment, a light-emitting device that can be used for a display panel of one embodiment of the present invention will be described.

[0237] 15A , the light-emitting device has an EL layer 786 between a pair of electrodes (a lower electrode 772 and an upper electrode 788). The EL layer 786 can be composed of multiple layers such as a layer 4420, a light-emitting layer 4411, and a layer 4430. The layer 4420 can have, for example, a layer containing a substance with high electron-injection properties (electron-injection layer) and a layer containing a substance with high electron-transport properties (electron-transport layer). The light-emitting layer 4411 contains, for example, a light-emitting compound. The layer 4430 can have, for example, a layer containing a substance with high hole-injection properties (hole-injection layer) and a layer containing a substance with high hole-transport properties (hole-transport layer).

[0238] A structure including the layer 4420, the light-emitting layer 4411, and the layer 4430 provided between a pair of electrodes can function as a single light-emitting unit, and the structure of FIG. 15A is referred to as a single structure in this specification.

[0239] 15B shows a modified example of the EL layer 786 included in the light-emitting device shown in Fig. 15A. Specifically, the light-emitting device shown in Fig. 15B includes a layer 4431 on a lower electrode 772, a layer 4432 on the layer 4431, a light-emitting layer 4411 on the layer 4432, a layer 4421 on the light-emitting layer 4411, a layer 4422 on the layer 4421, and an upper electrode 788 on the layer 4422. For example, when the lower electrode 772 is an anode and the upper electrode 788 is a cathode, the layer 4431 functions as a hole injection layer, the layer 4432 functions as a hole transport layer, the layer 4421 functions as an electron transport layer, and the layer 4422 functions as an electron injection layer. Alternatively, when the lower electrode 772 is a cathode and the upper electrode 788 is an anode, the layer 4431 functions as an electron injection layer, the layer 4432 functions as an electron transport layer, the layer 4421 functions as a hole transport layer, and the layer 4422 functions as a hole injection layer. With such a layer structure, carriers can be efficiently injected into the light-emitting layer 4411, and the efficiency of carrier recombination in the light-emitting layer 4411 can be increased.

[0240] As shown in FIGS. 15C and 15D, a configuration in which a plurality of light-emitting layers (light-emitting layers 4411, 4412, and 4413) are provided between the layer 4420 and the layer 4430 is also a variation of the single structure.

[0241] 15E and 15F, a configuration in which a plurality of light-emitting units (EL layer 786a, EL layer 786b) are connected in series via a charge generation layer 4440 is referred to as a tandem structure in this specification. The tandem structure may also be referred to as a stack structure. The tandem structure makes it possible to provide a light-emitting device capable of emitting light with high brightness.

[0242] 15C and 15D , light-emitting materials that emit light of the same color, or even the same light-emitting material, may be used for the light-emitting layers 4411, 4412, and 4413. For example, a light-emitting material that emits blue light may be used for the light-emitting layers 4411, 4412, and 4413. A color conversion layer may be provided as the layer 785 shown in FIG.

[0243] Furthermore, light-emitting materials that emit light of different colors may be used for the light-emitting layer 4411, the light-emitting layer 4412, and the light-emitting layer 4413. When the lights emitted by the light-emitting layer 4411, the light-emitting layer 4412, and the light-emitting layer 4413 are complementary in color, white light can be obtained. A color filter (also referred to as a coloring layer) may be provided as the layer 785 shown in FIG. 15D. When white light passes through the color filter, light of a desired color can be obtained.

[0244] 15E and 15F , the light-emitting layer 4411 and the light-emitting layer 4412 may be made of light-emitting materials that emit light of the same color, or even the same light-emitting material. Alternatively, the light-emitting layer 4411 and the light-emitting layer 4412 may be made of light-emitting materials that emit light of different colors. When the light emitted by the light-emitting layer 4411 and the light emitted by the light-emitting layer 4412 are complementary colors, white light is obtained. FIG. 15F shows an example in which a layer 785 is further provided. As the layer 785, one or both of a color conversion layer and a color filter (coloring layer) can be used.

[0245] 15C, 15D, 15E, and 15F, the layer 4420 and the layer 4430 may have a laminated structure consisting of two or more layers, as shown in FIG. 15B.

[0246] A structure that produces different luminescent colors (for example, blue (B), green (G), and red (R)) for each light-emitting device is sometimes called an SBS (Side By Side) structure.

[0247] The light-emitting device can emit light of red, green, blue, cyan, magenta, yellow, or white, depending on the material of the EL layer 786. Furthermore, the color purity can be further improved by providing the light-emitting device with a microcavity structure.

[0248] A light-emitting device that emits white light preferably has a configuration in which two or more types of light-emitting materials are contained in the light-emitting layer. To obtain white light emission, light-emitting materials can be selected such that the respective emissions of the two or more light-emitting materials have a complementary color relationship. For example, by making the emission color of the first light-emitting layer and the emission color of the second light-emitting layer complementary to each other, a light-emitting device that emits white light as a whole can be obtained. The same applies to light-emitting devices having three or more light-emitting layers.

[0249] The light-emitting layer preferably contains two or more light-emitting materials that emit light of R (red), G (green), B (blue), Y (yellow), O (orange), etc. Alternatively, the light-emitting layer preferably contains two or more light-emitting materials, each of which emits light containing spectral components of two or more colors of R, G, and B.

[0250] This embodiment mode can be implemented by appropriately combining at least a part thereof with other embodiment modes described in this specification.

[0251] Embodiment 3 In this embodiment, a display device of one embodiment of the present invention will be described with reference to FIGS.

[0252] The display device of the present embodiment can be a high-resolution display device or a large-sized display device. Therefore, the display device of the present embodiment can be used in electronic devices having relatively large screens, such as television devices, desktop or notebook personal computers, computer monitors, digital signage, large game machines such as pachinko machines, as well as display units of digital cameras, digital video cameras, digital photo frames, mobile phones, portable game machines, personal digital assistants, and sound reproducing devices.

[0253] [Display Device 100A] Fig. 16 shows a perspective view of the display device 100A, and Fig. 17A shows a cross-sectional view of the display device 100A. Fig. 18 shows a display device 100A' as a modification of Fig. 17A.

[0254] The display device 100A has a configuration in which a substrate 152 and a substrate 151 are bonded together. In Fig. 16, the substrate 152 is clearly indicated by a dashed line.

[0255] The display device 100A includes a display portion 162, a circuit 164, wiring 165, and the like. Fig. 16 shows an example in which an IC 173 and an FPC 172 are mounted on the display device 100A. Therefore, the configuration shown in Fig. 16 can also be considered a display module including the display device 100A, an IC (integrated circuit), and an FPC.

[0256] The circuit 164 can be, for example, a scanning line driver circuit.

[0257] The wiring 165 has a function of supplying signals and power to the display portion 162 and the circuit 164. The signals and power are input to the wiring 165 from the outside via the FPC 172 or from the IC 173.

[0258] 16 shows an example in which an IC 173 is provided on a substrate 151 by a chip-on-glass (COG) method or a chip-on-film (COF) method. The IC 173 may be, for example, an IC having a scanning line driver circuit or a signal line driver circuit. The display device 100A and the display module may not include an IC. Alternatively, the IC may be mounted on an FPC by a COF method or the like.

[0259] FIG. 17A shows an example of a cross section of the display device 100A, in which a part of a region including the FPC 172, a part of the circuit 164, a part of the display unit 162, and a part of a region including an end portion are cut away.

[0260] 17A includes a transistor 201, a transistor 205, and light-emitting devices 130a, 130b, and 130c between a substrate 151 and a substrate 152. The light-emitting devices 130a, 130b, and 130c have the function of emitting light of different colors.

[0261] Here, when a pixel of the display device has sub-pixels having light-emitting devices 130a, 130b, and 130c that emit light of different colors, the three sub-pixels include sub-pixels of three colors of R, G, and B, or sub-pixels of three colors of yellow (Y), cyan (C), and magenta (M), etc. When a pixel of the display device has four sub-pixels, the four sub-pixels include sub-pixels of four colors of R, G, B, and white (W), or sub-pixels of four colors of R, G, B, and Y, etc.

[0262] The light-emitting devices 130a, 130b, and 130c each have the layered structure shown in FIG. 1B except that an optical adjustment layer 126 (conductive layers 126a, 126b, and 126c) is provided between the pixel electrode and the EL layer. The light-emitting device 130a has the conductive layer 126a, the light-emitting device 130b has the conductive layer 126b, and the light-emitting device 130c has the conductive layer 126c. For details of the light-emitting devices, see Embodiment 1. Side surfaces of the pixel electrodes 111a, 111b, and 111c, the conductive layers 126a, 126b, and 126c, the first layer 112, the light-emitting layer 113, and the second layer 114 are covered with insulating layers 125 and 127, respectively. A third layer 115 is provided on the first layer 112, the light-emitting layer 113, the second layer 114, and the insulating layers 125 and 127, and a common electrode 116 is provided on the third layer 115. A protective layer 131 is provided on each of the light-emitting devices 130a, 130b, and 130c. A protective layer 132 is provided on the protective layer 131. The structures between pixel electrodes and the structures of the pixel electrode ends can be referenced from the structures shown in FIGS. 1 to 7. For example, the pixel electrode 111a in FIGS. 1 to 7 corresponds to the pixel electrode 111a and conductive layer 126a in FIGS. 17A and 18, and the height of the step between adjacent pixel electrodes in FIG. 17A is the height of the pixel electrode 111a and conductive layer 126a. 18 can be set to the sum of the pixel electrode 111a and the conductive layer 126a and the depth of the recess (step) provided at that location in the insulating layer 214. Note that Fig. 18 has the same structure as Fig. 17 except for the recess provided in the insulating layer 214.

[0263] 17A , it is preferable that the optical adjustment layer 126 provided in each light-emitting device 130 has a different thickness for each light-emitting device. Alternatively, if the optical adjustment layer 126 has the same thickness for each light-emitting device, it is preferable that the thickness of the EL layer of each light-emitting device is different.

[0264] The protective layer 132 and the substrate 152 are bonded via an adhesive layer 142. A solid sealing structure, a hollow sealing structure, or the like can be applied to seal the light-emitting device. In FIG. 17A , the space between the substrates 152 and 151 is filled with the adhesive layer 142, and a solid sealing structure is applied. Alternatively, the space may be filled with an inert gas (such as nitrogen or argon), and a hollow sealing structure may be applied. In this case, the adhesive layer 142 may be provided so as not to overlap with the light-emitting device. Alternatively, the space may be filled with a resin different from the frame-shaped adhesive layer 142.

[0265] The pixel electrodes 111 a , 111 b , and 111 c are connected to the conductive layers 222 a , 222 b , and 222 c of the transistor 205 through openings provided in the insulating layer 214 , respectively.

[0266] Recesses are formed in the pixel electrodes 111a, 111b, and 111c so as to cover the openings provided in the insulating layer 214. The recesses are preferably filled with a layer 128. A conductive layer 126a is preferably formed over the pixel electrode 111a and the layer 128, a conductive layer 126b is preferably formed over the pixel electrode 111b and the layer 128, and a conductive layer 126c is preferably formed over the pixel electrode 111c and the layer 128. The conductive layers 126a, 126b, and 126c can also be referred to as pixel electrodes.

[0267] The layer 128 has a function of planarizing the recesses of the pixel electrodes 111a, 111b, and 111c. By providing the layer 128, unevenness of the surface on which the EL layer is formed can be reduced, and coverage can be improved. Furthermore, by providing conductive layers 126a, 126b, and 126c electrically connected to the pixel electrodes 111a, 111b, and 111c over the pixel electrodes 111a, 111b, and 111c and the layer 128, regions overlapping with the recesses of the pixel electrodes 111a, 111b, and 111c can also be used as light-emitting regions in some cases. This can increase the aperture ratio of the pixel.

[0268] The layer 128 may be an insulating layer or a conductive layer. Various inorganic insulating materials, organic insulating materials, and conductive materials can be used as appropriate for the layer 128. In particular, the layer 128 is preferably formed using an insulating material.

[0269] An insulating layer containing an organic material can be suitably used as the layer 128. For example, acrylic resin, polyimide resin, epoxy resin, polyamide resin, polyimideamide resin, siloxane resin, benzocyclobutene resin, phenol resin, precursors of these resins, or the like can be used as the layer 128. Alternatively, a photosensitive resin can be used as the layer 128. The photosensitive resin can be a positive-type material or a negative-type material.

[0270] By using a photosensitive resin, the layer 128 can be formed only by exposure and development steps, and the influence of dry etching, wet etching, etc. on the surfaces of the pixel electrodes 111a, 111b, and 111c can be reduced. Furthermore, by forming the layer 128 using a negative photosensitive resin, the layer 128 can sometimes be formed using the same photomask (exposure mask) as that used to form the openings in the insulating layer 214.

[0271] The conductive layer 126a is provided on the pixel electrode 111a and the layer 128. The conductive layer 126a has a first region in contact with the upper surface of the pixel electrode 111a and a second region in contact with the upper surface of the layer 128. It is preferable that the height of the upper surface of the pixel electrode 111a in contact with the first region and the height of the upper surface of the layer 128 in contact with the second region are the same or approximately the same.

[0272] Similarly, the conductive layer 126b is provided on the pixel electrode 111b and the layer 128. The conductive layer 126b has a first region in contact with the upper surface of the pixel electrode 111b and a second region in contact with the upper surface of the layer 128. It is preferable that the height of the upper surface of the pixel electrode 111b in contact with the first region and the height of the upper surface of the layer 128 in contact with the second region are the same or approximately the same.

[0273] The conductive layer 126c is provided on the pixel electrode 111c and the layer 128. The conductive layer 126c has a first region in contact with the upper surface of the pixel electrode 111c and a second region in contact with the upper surface of the layer 128. It is preferable that the height of the upper surface of the pixel electrode 111c in contact with the first region and the height of the upper surface of the layer 128 in contact with the second region are the same or approximately the same.

[0274] The pixel electrode includes a material that reflects visible light, and the counter electrode includes a material that transmits visible light.

[0275] The display device 100A is a top-emission type. Light emitted from the light-emitting device is emitted toward the substrate 152. The substrate 152 is preferably made of a material that is highly transparent to visible light.

[0276] The stacked structure from the substrate 151 to the insulating layer 214 corresponds to the layer 101 including the transistor in Embodiment 1.

[0277] The transistor 201 and the transistor 205 are both formed over a substrate 151. These transistors can be manufactured using the same material and through the same process.

[0278] An insulating layer 211, an insulating layer 213, an insulating layer 215, and an insulating layer 214 are provided over the substrate 151 in this order. A part of the insulating layer 211 functions as a gate insulating layer for each transistor. A part of the insulating layer 213 functions as a gate insulating layer for each transistor. The insulating layer 215 is provided to cover the transistor. The insulating layer 214 is provided to cover the transistor and functions as a planarization layer. Note that the number of gate insulating layers and the number of insulating layers covering the transistors are not limited, and each may be a single layer or two or more layers.

[0279] At least one insulating layer covering the transistor is preferably made of a material that is resistant to the diffusion of impurities such as water and hydrogen. This allows the insulating layer to function as a barrier layer. With this structure, it is possible to effectively prevent impurities from diffusing into the transistor from the outside, thereby improving the reliability of the display device.

[0280] It is preferable to use an inorganic insulating film for each of the insulating layers 211, 213, and 215. Examples of the inorganic insulating film that can be used include a silicon nitride film, a silicon oxynitride film, a silicon oxide film, a silicon nitride oxide film, an aluminum oxide film, and an aluminum nitride film. Alternatively, 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, and a neodymium oxide film may also be used. Two or more of the above insulating films may be stacked.

[0281] Here, organic insulating films often have lower barrier properties than inorganic insulating films. Therefore, it is preferable that the organic insulating film has an opening near the edge of the display device 100A. This can prevent impurities from entering through the edge of the display device 100A via the organic insulating film. Alternatively, the organic insulating film may be formed so that the edge of the organic insulating film is located inside the edge of the display device 100A, so that the organic insulating film is not exposed at the edge of the display device 100A.

[0282] An organic insulating film is suitable for the insulating layer 214, which functions as a planarization layer. Materials that can be used for the organic insulating film include acrylic resin, polyimide resin, epoxy resin, polyamide resin, polyimideamide resin, siloxane resin, benzocyclobutene-based resin, phenolic resin, and precursors of these resins. The insulating layer 214 may also have a laminated structure of an organic insulating film and an inorganic insulating film. The outermost layer of the insulating layer 214 preferably functions as an etching protection film. This can prevent recesses from being formed in the insulating layer 214 during processing of the pixel electrode 111a, the conductive layer 126a, etc. Alternatively, recesses may be formed in the insulating layer 214 during processing of the pixel electrode 111a, the conductive layer 126a, etc.

[0283] 17A , an opening is formed in insulating layer 214. This makes it possible to prevent impurities from entering display unit 162 from the outside through insulating layer 214, even when an organic insulating film is used for insulating layer 214. This makes it possible to improve the reliability of display device 100A.

[0284] The transistor 201 and the transistor 205 each include a conductive layer 221 that functions as a gate, an insulating layer 211 that functions as a gate insulating layer, conductive layers 222a and 222b that function as a source and a drain, a semiconductor layer 231, an insulating layer 213 that functions as a gate insulating layer, and a conductive layer 223 that functions as a gate. Here, the same hatching pattern is applied to multiple layers obtained by processing the same conductive film. The insulating layer 211 is located between the conductive layer 221 and the semiconductor layer 231. The insulating layer 213 is located between the conductive layer 223 and the semiconductor layer 231.

[0285] The structure of the transistor included in the display device of this embodiment is not particularly limited. For example, a planar transistor, a staggered transistor, an inverted staggered transistor, or the like can be used. Furthermore, either a top-gate transistor or a bottom-gate transistor structure may be used. Alternatively, gates may be provided above and below a semiconductor layer in which a channel is formed.

[0286] The transistor 201 and the transistor 205 have a structure in which a semiconductor layer in which a channel is formed is sandwiched between two gates. The two gates may be connected and the same signal may be supplied to drive the transistor. Alternatively, the threshold voltage of the transistor may be controlled by applying a potential for controlling the threshold voltage to one of the two gates and a potential for driving to the other.

[0287] The crystallinity of a semiconductor material used for a transistor is not particularly limited, and any of an amorphous semiconductor and a crystalline semiconductor (a microcrystalline semiconductor, a polycrystalline semiconductor, a single crystal semiconductor, or a semiconductor having a crystalline region in part) may be used. The use of a crystalline semiconductor is preferable because it can suppress deterioration of transistor characteristics.

[0288] The semiconductor layer of the transistor preferably contains metal oxide (also referred to as an oxide semiconductor). That is, the display device of this embodiment preferably uses a transistor in which a channel formation region is formed using metal oxide (hereinafter referred to as an OS transistor). Alternatively, the semiconductor layer of the transistor may contain silicon. Examples of silicon include amorphous silicon and crystalline silicon (such as low-temperature polysilicon and single-crystal silicon).

[0289] The semiconductor layer preferably contains, for example, indium, M (wherein M is one or more elements 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), and zinc. In particular, M is preferably one or more elements selected from aluminum, gallium, yttrium, and tin.

[0290] In particular, it is preferable to use an oxide containing indium (In), gallium (Ga), and zinc (Zn) (also referred to as IGZO) as the semiconductor layer.

[0291] When the semiconductor layer is an In-M-Zn oxide, the atomic ratio of In in the In-M-Zn oxide is preferably equal to or greater than the atomic ratio of M. Examples of atomic ratios of metal elements in such In-M-Zn oxides include a composition in which In:M:Zn=1:1:1 or thereabouts, a composition in which In:M:Zn=1:1:1.2 or thereabouts, a composition in which In:M:Zn=2:1:3 or thereabouts, a composition in which In:M:Zn=3:1:2 or thereabouts, a composition in which In:M:Zn=4:2:3 or thereabouts, a composition in which In:M:Zn=4:2:4.1 or thereabouts, a composition in which In:M:Zn=5:1:3 or thereabouts, a composition in which In:M:Zn=5:1:6 or thereabouts, a composition in which In:M:Zn=5:1:7 or thereabouts, a composition in which In:M:Zn=5:1:8 or thereabouts, a composition in which In:M:Zn=6:1:6 or thereabouts, and a composition in which In:M:Zn=5:2:5 or thereabouts. The term "nearby composition" includes a range of ±30% of the desired atomic ratio.

[0292] For example, when describing a composition having an atomic ratio of In:Ga:Zn=4:2:3 or thereabout, this includes a case where, when the atomic ratio of In is 4, the atomic ratio of Ga is 1 or more and 3 or less, and the atomic ratio of Zn is 2 or more and 4 or less. Furthermore, when describing a composition having an atomic ratio of In:Ga:Zn=5:1:6 or thereabout, this includes a case where, when the atomic ratio of In is 5, the atomic ratio of Ga is more than 0.1 and 2 or less, and the atomic ratio of Zn is 5 or more and 7 or less. Furthermore, when describing a composition having an atomic ratio of In:Ga:Zn=1:1:1 or thereabout, this includes a case where, when the atomic ratio of In is 1, the atomic ratio of Ga is more than 0.1 and 2 or less, and the atomic ratio of Zn is more than 0.1 and 2 or less.

[0293] The transistors included in the circuit 164 may have the same structure as or different from the transistors included in the display portion 162. The transistors included in the circuit 164 may all have the same structure or may have two or more types. Similarly, the transistors included in the display portion 162 may all have the same structure or may have two or more types.

[0294] 17B and 17C show other examples of transistor configurations.

[0295] The transistor 209 and the transistor 210 each include a conductive layer 221 functioning as a gate, an insulating layer 211 functioning as a gate insulating layer, a semiconductor layer 231 including a channel formation region 231i and a pair of low-resistance regions 231n, a conductive layer 222a connected to one of the pair of low-resistance regions 231n, a 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, a conductive layer 223 functioning as a gate, and an insulating layer 215 covering the conductive layer 223. The insulating layer 211 is located between the conductive layer 221 and the channel formation region 231i. The insulating layer 225 is located at least between the conductive layer 223 and the channel formation region 231i. Furthermore, an insulating layer 218 covering the transistor may be provided.

[0296] 17B shows an example 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 region 231n through openings provided in the insulating layer 225 and the insulating layer 215, respectively. One of the conductive layer 222a and the conductive layer 222b functions as a source, and the other functions as a drain.

[0297] 17C , the insulating layer 225 overlaps with the channel formation region 231i of the semiconductor layer 231 but does not overlap with the low-resistance region 231n. For example, the insulating layer 225 is processed using the conductive layer 223 as a mask, thereby manufacturing the structure shown in FIG. 17C . In FIG. 17C , 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 region 231n through openings in the insulating layer 215.

[0298] A connection portion 204 is provided in a region of the substrate 151 where the substrate 152 does not overlap. In the connection portion 204, the wiring 165 is electrically connected to the FPC 172 via a conductive layer 166 and a connection layer 242. The conductive layer 166 has an example of a stacked structure including a conductive film obtained by processing the same conductive film as the pixel electrodes 111a, 111b, and 111c and a conductive film obtained by processing the same conductive film as the conductive layers 126a, 126b, and 126c. The conductive layer 166 is exposed on the top surface of the connection portion 204. This allows the connection portion 204 and the FPC 172 to be electrically connected via the connection layer 242.

[0299] As shown in FIG. 17A, it is preferable to provide a light-shielding layer 117 on the surface of the substrate 152 facing the substrate 151 .

[0300] Various optical members may be disposed on the outside of the substrate 152. Examples of optical members include a polarizing plate, a retardation plate, a light diffusion layer (such as a diffusion film), an anti-reflection layer, and a light-collecting film. The outside of the substrate 152 may also be provided with an anti-static film that suppresses the adhesion of dust, a water-repellent film that makes it difficult for dirt to adhere, a hard coat film that suppresses scratches that occur during use, an impact absorbing layer, and the like.

[0301] By providing the protective layers 131 and 132 that cover the light-emitting device, impurities such as water can be prevented from entering the light-emitting device, and the reliability of the light-emitting device can be improved.

[0302] In a region 228 near the edge of the display device 100A, it is preferable that the insulating layer 215 and the protective layer 131 or the protective layer 132 contact each other through the opening in the insulating layer 214. In particular, it is preferable that the inorganic insulating films contact each other. This makes it possible to prevent impurities from entering the display unit 162 from the outside via the organic insulating film. This can therefore improve the reliability of the display device 100A.

[0303] The substrate 151 and the substrate 152 can each be made of glass, quartz, ceramic, sapphire, resin, metal, alloy, semiconductor, or the like. A material that transmits light is used for the substrate on the side from which light from the light-emitting device is extracted. Using a flexible material for the substrate 151 and the substrate 152 can increase the flexibility of the display device. Alternatively, a polarizing plate may be used for the substrate 151 or the substrate 152.

[0304] Substrates 151 and 152 may each be made of polyester resin such as polyethylene terephthalate (PET) or polyethylene naphthalate (PEN), polyacrylonitrile resin, acrylic resin, polyimide resin, polymethyl methacrylate resin, polycarbonate (PC) resin, polyethersulfone (PES) resin, polyamide resin (nylon, aramid, etc.), polysiloxane resin, cycloolefin resin, polystyrene resin, polyamideimide resin, polyurethane resin, polyvinyl chloride resin, polyvinylidene chloride resin, polypropylene resin, polytetrafluoroethylene (PTFE) resin, ABS resin, cellulose nanofiber, etc. One or both of substrates 151 and 152 may be made of glass having a thickness sufficient to provide flexibility.

[0305] When a circularly polarizing plate is superimposed on a display device, it is preferable that the display device has a substrate with high optical isotropy. A substrate with high optical isotropy has small birefringence (or a small amount of birefringence).

[0306] The absolute value of the retardation (phase difference) of a substrate having high optical isotropy is preferably 30 nm or less, more preferably 20 nm or less, and even more preferably 10 nm or less.

[0307] Examples of films with high optical isotropy include triacetyl cellulose (TAC, also known as cellulose triacetate) films, cycloolefin polymer (COP) films, cycloolefin copolymer (COC) films, and acrylic films.

[0308] Furthermore, when a film is used as a substrate, the film may absorb water, causing deformation such as wrinkles in the display panel. Therefore, it is preferable to use a film with low water absorption for the substrate. For example, it is preferable to use a film with a water absorption rate of 1% or less, more preferably 0.1% or less, and even more preferably 0.01% or less.

[0309] The adhesive layer 142 can be made of various curable adhesives, such as a photo-curable adhesive (e.g., an ultraviolet curable adhesive), a reactive curable adhesive, a thermosetting adhesive, or an anaerobic adhesive. Examples of such adhesives include epoxy resin, acrylic resin, silicone resin, phenolic resin, polyimide resin, imide resin, PVC (polyvinyl chloride) resin, PVB (polyvinyl butyral) resin, and EVA (ethylene vinyl acetate) resin. In particular, a material with low moisture permeability, such as epoxy resin, is preferable. Alternatively, a two-component resin may be used. Alternatively, an adhesive sheet or the like may be used.

[0310] The connection layer 242 may be an anisotropic conductive film (ACF), an anisotropic conductive paste (ACP), or the like.

[0311] Materials that can be used for conductive layers such as the gate, source, and drain of a transistor, as well as various wirings and electrodes that constitute a display device include metals such as aluminum, titanium, chromium, nickel, copper, yttrium, zirconium, molybdenum, silver, tantalum, and tungsten, and alloys containing these metals as main components, etc. Films containing these materials can be used as a single layer or a stacked layer structure.

[0312] Examples of light-transmitting conductive materials include conductive oxides such as indium oxide, indium tin oxide, indium zinc oxide, zinc oxide, and zinc oxide containing gallium, or graphene. Alternatively, metal materials such as gold, silver, platinum, magnesium, nickel, tungsten, chromium, molybdenum, iron, cobalt, copper, palladium, and titanium, or alloy materials containing such metal materials, can be used. Alternatively, nitrides of such metal materials (e.g., titanium nitride) can be used. When using metal materials or alloy materials (or their nitrides), it is preferable to thin them sufficiently to ensure light-transmitting properties. A stacked film of the above materials can also be used as the conductive layer. For example, a stacked film of an alloy of silver and magnesium and indium tin oxide is preferable because it can enhance conductivity. These materials can also be used for conductive layers such as various wirings and electrodes constituting display devices, and conductive layers (conductive layers functioning as pixel electrodes or common electrodes) in light-emitting devices.

[0313] Examples of insulating materials that can be used for each insulating layer include resins such as acrylic resin and epoxy resin, and inorganic insulating materials such as silicon oxide, silicon oxynitride, silicon nitride oxide, silicon nitride, and aluminum oxide.

[0314] [Display Device 100B] The display device 100B shown in FIG. 19 and the display device 100B' shown in FIG. 20 differ from the display device 100A mainly in that they are bottom-emission types. Descriptions of parts similar to those of the display device 100A will be omitted. The display device 100B' shown in FIG. 20 has the same structure as the display device 100B shown in FIG. 19 except that the insulating layer 214 has a recess (step) between the pixel electrodes. Although FIGS. 19 and 20 show a subpixel including a first layer 112 and a subpixel including a light-emitting layer 113, three or more types of subpixels can be provided, as in FIG. 17 and the like.

[0315] Light emitted from the light-emitting device is emitted toward the substrate 151. A material that is highly transparent to visible light is preferably used for the substrate 151. On the other hand, the light-transmitting property of the material used for the substrate 152 does not matter.

[0316] In the display device 100B, the pixel electrodes 111a, 111b, and 111c and the conductive layers 126a, 126b, and 126c contain a material that transmits visible light, and the common electrode 116 contains a material that reflects visible light. Here, the conductive layer 166, which is obtained by processing the same conductive film as the pixel electrodes 111a, 111b, and 111c and the conductive layers 126a, 126b, and 126c, also contains a material that transmits visible light.

[0317] A light-shielding layer 117 is preferably formed between the substrate 151 and the transistor 201 and between the substrate 151 and the transistor 205. Fig. 19 shows an example in which the light-shielding layer 117 is provided over the substrate 151, the insulating layer 153 is provided over the light-shielding layer 117, and the transistors 201, 205, and the like are provided over the insulating layer 153.

[0318] 21A to 21D show cross-sectional structures of a region 138 including the pixel electrode 111a, the layer 128, and their peripheries for the display device 100A and the display device 100B. The same applies to the light-emitting device 130b and the light-emitting device 130c as described in FIGS. 21A to 21D.

[0319] 17A, 18, 19, and 20 show examples in which the top surface of the layer 128 and the top surface of the pixel electrode 111a are roughly aligned, but the present invention is not limited to this. For example, as shown in Fig. 21A, the top surface of the layer 128 may be higher than the top surface of the pixel electrode 111a. In this case, the top surface of the layer 128 has a shape that is gently bulging outward in a convex shape toward the center.

[0320] 21B, the upper surface of the layer 128 may be lower than the upper surface of the pixel electrode 111a. In this case, the upper surface of the layer 128 has a gently sloping recessed shape that is concave toward the center.

[0321] 21C , when the upper surface of the layer 128 is higher than the upper surface of the pixel electrode 111a, the upper part of the layer 128 may be formed to extend beyond the recess formed in the pixel electrode 111a. In this case, part of the layer 128 may be formed to cover part of the approximately flat region of the pixel electrode 111a.

[0322] 21D, in the structure shown in Fig. 21C, a recess may be further formed in part of the upper surface of layer 128. The recess has a shape that is gently recessed toward the center.

[0323] This embodiment mode can be combined with other embodiment modes as appropriate.

[0324] Embodiment 4 In this embodiment, a display device of one embodiment of the present invention will be described with reference to FIGS.

[0325] The display device of the present embodiment can be a high-definition display device, and therefore can be used as a display unit of a wearable device that can be worn on the head, such as a wristwatch-type or bracelet-type information terminal (wearable device), a head-mounted display or other VR (Virtual Reality) device, or a glasses-type AR (Augmented Reality) device.

[0326] 22A shows a perspective view of a display module 280. The display module 280 includes a display device 100C and an FPC 290. Note that the display device included in the display module 280 is not limited to the display device 100C, and may be any of display devices 100D to 100G described below.

[0327] The display module 280 has a substrate 291 and a substrate 292. The display module 280 has a display portion 281. The display portion 281 is a region that displays an image in the display module 280, and is a region where light from each pixel provided in a pixel portion 284 (described later) can be viewed.

[0328] 22B is a perspective view schematically illustrating the configuration on the substrate 291 side. A circuit portion 282, a pixel circuit portion 283 on the circuit portion 282, and a pixel portion 284 on the pixel circuit portion 283 are stacked on the substrate 291. A terminal portion 285 for connecting to the FPC 290 is provided in a portion of the substrate 291 that does not overlap with the pixel portion 284. The terminal portion 285 and the circuit portion 282 are electrically connected by a wiring portion 286 composed of a plurality of wirings.

[0329] The pixel section 284 has a plurality of periodically arranged pixels 284a. An enlarged view of one pixel 284a is shown on the right side of FIG. 22B . The pixel 284a has subpixels 110a, 110b, and 110c. The previous embodiment can be referred to for the configuration of the subpixels 110a, 110b, and 110c and their surroundings. The plurality of subpixels can be arranged in a stripe array as shown in FIG. 22B . Various light-emitting device arrangement methods, such as a delta array or a pentile array, can also be applied.

[0330] The pixel circuit section 283 has a plurality of pixel circuits 283a arranged periodically.

[0331] One pixel circuit 283a is a circuit that controls the light emission of three light-emitting devices included in one pixel 284a. One pixel circuit 283a may be configured to have three circuits that control the light emission of one light-emitting device. For example, the pixel circuit 283a may be configured to have at least one selection transistor, one current control transistor (drive transistor), and a capacitor element for each light-emitting device. In this case, a gate signal is input to the gate of the selection transistor, and a source signal is input to either the source or the drain. This realizes an active matrix display device.

[0332] The circuit portion 282 includes a circuit for driving each pixel circuit 283 a of 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. In addition, the circuit portion 282 may include at least one of an arithmetic circuit, a memory circuit, a power supply circuit, and the like.

[0333] The FPC 290 functions as wiring for supplying a video signal, a power supply potential, or the like from the outside to the circuit portion 282. An IC may be mounted on the FPC 290.

[0334] The display module 280 can be configured such that one or both of the pixel circuit unit 283 and the circuit unit 282 are stacked below the pixel unit 284, thereby enabling the aperture ratio (effective display area ratio) of the display unit 281 to be extremely high. For example, the aperture ratio of the display unit 281 can be 40% or more and less than 100%, preferably 50% or more and 95% or less, and more preferably 60% or more and 95% or less. Furthermore, the pixels 284a can be arranged at an extremely high density, enabling the resolution of the display unit 281 to be extremely high. For example, it is preferable that the pixels 284a be arranged in the display unit 281 at a resolution of 2000 ppi or more, preferably 3000 ppi or more, more preferably 5000 ppi or more, and even more preferably 6000 ppi or more, and 20,000 ppi or less, or 30,000 ppi or less.

[0335] Because such a display module 280 has extremely high resolution, it can be suitably used in VR devices such as head-mounted displays, or in glasses-type AR devices. For example, even in a configuration in which the display unit of the display module 280 is viewed through lenses, the display module 280 has an extremely high-resolution display unit 281, so even when the display unit is enlarged with lenses, the pixels are not visible, allowing for a highly immersive display. Furthermore, the display module 280 is not limited to this, and can be suitably used in electronic devices with relatively small display units. For example, it can be suitably used in the display unit of a wearable electronic device such as a wristwatch.

[0336] 23 includes a substrate 301, subpixels 110a, 110b, and 110c, a capacitor 240, and a transistor 310. The subpixel 110a includes a light-emitting device 130a, the subpixel 110b includes a light-emitting device 130b, and the subpixel 110c includes a light-emitting device 130c.

[0337] 22A and 22B. The stacked structure from the substrate 301 to the insulating layer 255b corresponds to the layer 101 including the transistor in Embodiment 1.

[0338] The transistor 310 has a channel formation region in a substrate 301. The substrate 301 can be, for example, a semiconductor substrate such as a single crystal silicon substrate. The transistor 310 includes a 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 located between the substrate 301 and the conductive layer 311 and functions as a gate insulating layer. The low-resistance region 312 is a region in which the substrate 301 is doped with impurities 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 and functions as an insulating layer.

[0339] An element isolation layer 315 is provided between two adjacent transistors 310 so as to be embedded in the substrate 301 .

[0340] In addition, an insulating layer 261 is provided to cover the transistor 310 , and a capacitor 240 is provided over the insulating layer 261 .

[0341] The capacitor 240 has a conductive layer 241, a conductive layer 245, and an insulating layer 243 located therebetween. 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.

[0342] The conductive layer 241 is provided over the insulating layer 261 and is buried in the insulating layer 254. The conductive layer 241 is electrically connected to one of the source and drain of the transistor 310 by a plug 271 buried 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 interposed therebetween.

[0343] An insulating layer 255a is provided to cover the capacitor 240, an insulating layer 255b is provided on the insulating layer 255a, and light-emitting devices 130a, 130b, 130c, etc. are provided on the insulating layer 255b. In this embodiment, an example is shown in which the light-emitting devices 130a, 130b, and 130c have the stacked structure shown in FIG. 1B . The side surface of the pixel electrode 111 may have a region in direct contact with the insulating layer 125 and a region in direct contact with the first layer 112. It is preferable that the first layer 112 has a structure in which the pixel electrodes are interrupted between adjacent pixel electrodes. A protective layer 131 is provided on the light-emitting devices 130a, 130b, and 130c. A protective layer 132 is provided on the protective layer 131, and a substrate 120 is attached to the protective layer 132 by a resin layer 122. For details of the components from the light-emitting devices to the substrate 120, refer to Embodiment 1. Substrate 120 corresponds to substrate 292 in FIG. 22A.

[0344] The insulating layers 255a and 255b can be formed using various inorganic insulating films such as an insulating oxide film, an insulating nitride film, an oxynitride insulating film, and an insulating nitride oxide film. The insulating layer 255a is preferably formed using an oxide insulating film or an oxynitride insulating film such as a silicon oxide film, a silicon oxynitride film, or an aluminum oxide film. The insulating layer 255b is preferably formed using a nitride insulating film or a nitride oxide insulating film such as a silicon nitride film or a silicon nitride oxide film. More specifically, the insulating layer 255a is preferably formed using a silicon oxide film, and the insulating layer 255b is preferably formed using a silicon nitride film. The insulating layer 255b preferably functions as an etching protective film. Alternatively, the insulating layer 255a may be formed using a nitride insulating film or a nitride oxide insulating film, and the insulating layer 255b may be formed using an oxide insulating film or an oxynitride insulating film. Although this embodiment shows an example in which a recess is provided in the insulating layer 255b, the insulating layer 255b does not necessarily have a recess.

[0345] The pixel electrode of the light-emitting device is electrically connected to one of the source and drain of the transistor 310 via a plug 256 embedded in the insulating layers 255a and 255b, a conductive layer 241 embedded in the insulating layer 254, and a plug 271 embedded in the insulating layer 261. The height of the top surface of the insulating layer 255b and the height of the top surface of the plug 256 are the same or approximately the same. Various conductive materials can be used for the plug.

[0346] 24 is different from the display device 100C mainly in the configuration of the transistors. Note that descriptions of parts that are the same as those of the display device 100C may be omitted.

[0347] The transistor 320 is a transistor (OS transistor) in which a metal oxide (also referred to as an oxide semiconductor) is used for a semiconductor layer in which a channel is formed.

[0348] 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 .

[0349] 22A and 22B . The stacked structure from the substrate 331 to the insulating layer 255b corresponds to the layer 101 including the transistor in Embodiment 1. The substrate 331 can be an insulating substrate or a semiconductor substrate.

[0350] An insulating layer 332 is provided over a substrate 331. The insulating layer 332 functions as a barrier layer that prevents impurities such as water or hydrogen from diffusing from the substrate 331 to the transistor 320 and prevents oxygen from being released from the semiconductor layer 321 toward the insulating layer 332. The insulating layer 332 can be, for example, a film through which hydrogen or oxygen is less likely to diffuse than a silicon oxide film, such as an aluminum oxide film, a hafnium oxide film, or a silicon nitride film.

[0351] A conductive layer 327 is provided over the insulating layer 332, and an 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 for at least a portion 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.

[0352] The semiconductor layer 321 is provided over the insulating layer 326. The semiconductor layer 321 preferably includes a metal oxide (also referred to as an oxide semiconductor) film having semiconductor properties. Materials that can be suitably used for the semiconductor layer 321 will be described in detail later.

[0353] 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.

[0354] An insulating layer 328 is provided to cover top surfaces and side surfaces of the pair of conductive layers 325 and side surfaces of the semiconductor layer 321, and an insulating layer 264 is provided over the insulating layer 328. The insulating layer 328 functions as a barrier layer that prevents impurities such as water or hydrogen from diffusing from the insulating layer 264 or the like to the semiconductor layer 321 and prevents oxygen from being released from the semiconductor layer 321. The insulating layer 328 can be an insulating film similar to the insulating layer 332.

[0355] Openings reaching the semiconductor layer 321 are provided in the insulating layer 328 and the insulating layer 264. Inside the openings, an insulating layer 323 and a conductive layer 324 are buried, which are in contact with side surfaces of the insulating layer 264, the insulating layer 328, and the conductive layer 325 and an upper surface of the semiconductor layer 321. The conductive layer 324 functions as a second gate electrode, and the insulating layer 323 functions as a second gate insulating layer.

[0356] The top surfaces of the conductive layer 324, the insulating layer 323, and the insulating layer 264 are planarized so that their heights are the same or approximately the same, and insulating layers 329 and 265 are provided to cover them.

[0357] 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 impurities such as water or hydrogen from diffusing from the insulating layer 265 or the like to the transistor 320. The insulating layer 329 can be formed using an insulating film similar to the insulating layer 328 and the insulating layer 332.

[0358] 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 surfaces of the openings of 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. In this case, the conductive layer 274a is preferably made of a conductive material through which hydrogen and oxygen do not easily diffuse.

[0359] The configuration of the display device 100D from the insulating layer 254 to the substrate 120 is the same as that of the display device 100C.

[0360] 25 has a stacked structure of a transistor 310 in which a channel is formed in a substrate 301 and a transistor 320 in which a channel is formed and a semiconductor layer containing metal oxide. Note that descriptions of parts similar to those of the display devices 100C and 100D may be omitted.

[0361] An 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 layers 251 and 252 each function as wirings. An insulating layer 263 and an insulating layer 332 are provided to cover the conductive layer 252, and the transistor 320 is provided over the insulating layer 332. An insulating layer 265 is provided to cover the transistor 320, and a capacitor 240 is provided over the insulating layer 265. The capacitor 240 and the transistor 320 are electrically connected by a plug 274.

[0362] The transistor 320 can be used as a transistor that forms a pixel circuit. The transistor 310 can be used as a transistor that forms a pixel circuit or a driver circuit (gate line driver circuit, source line driver circuit) that drives the pixel circuit. The transistors 310 and 320 can be used as transistors that form various circuits such as an arithmetic circuit or a memory circuit.

[0363] By using this configuration, not only pixel circuits but also driving circuits etc. can be formed directly below the light-emitting device, making it possible to make the display device smaller than when driving circuits are provided around the periphery of the display area.

[0364] [Display Device 100F] A display device 100F shown in FIG. 26 has a stacked structure of a transistor 310A and a transistor 310B, each of which has a channel formed in a semiconductor substrate.

[0365] The display device 100F has a configuration in which a substrate 301B on which a transistor 310B, a capacitor 240, and each light-emitting device are provided and a substrate 301A on which a transistor 310A is provided are bonded together.

[0366] Here, it is preferable to provide an insulating layer 345 on the lower surface of the substrate 301B. It is also preferable to provide an insulating layer 346 on the insulating layer 261 provided on the substrate 301A. The insulating layers 345 and 346 are insulating layers that function as protective layers and can suppress the diffusion of impurities into the substrates 301B and 301A. As the insulating layers 345 and 346, an inorganic insulating film that can be used for the protective layers 131 and 132 or the insulating layer 332 can be used.

[0367] The substrate 301B is provided with a plug 343 that penetrates the substrate 301B and an insulating layer 345. Here, it is preferable to provide an insulating layer 344 to cover the side surface of the plug 343. The insulating layer 344 is an insulating layer that functions as a protective layer and can suppress the diffusion of impurities into the substrate 301B. As the insulating layer 344, an inorganic insulating film that can be used for the protective layers 131, 132, or the insulating layer 332 can be used.

[0368] Furthermore, a conductive layer 342 is provided on the back surface (surface opposite to the substrate 120 side) of the substrate 301B, below the insulating layer 345. The conductive layer 342 is preferably provided so as to be embedded in the insulating layer 335. Furthermore, the lower surfaces of the conductive layer 342 and the insulating layer 335 are preferably flattened. Here, the conductive layer 342 is electrically connected to the plug 343.

[0369] On the other hand, in the substrate 301A, a conductive layer 341 is provided on an insulating layer 346. The conductive layer 341 is preferably provided so as to be embedded in the insulating layer 336. In addition, the upper surfaces of the conductive layer 341 and the insulating layer 336 are preferably flattened.

[0370] The substrate 301A and the substrate 301B are electrically connected by bonding the conductive layer 341 and the conductive layer 342. Here, by improving the flatness of the surface formed by the conductive layer 342 and the insulating layer 335 and the surface formed by the conductive layer 341 and the insulating layer 336, the conductive layer 341 and the conductive layer 342 can be favorably bonded to each other.

[0371] It is preferable to use the same conductive material for the conductive layers 341 and 342. For example, a metal film containing an element selected from Al, Cr, Cu, Ta, Ti, Mo, and W, or a metal nitride film containing the above elements (titanium nitride film, molybdenum nitride film, tungsten nitride film), etc., can be used. In particular, it is preferable to use copper for the conductive layers 341 and 342. This allows the use of Cu-Cu (copper-copper) direct bonding technology (technology that achieves electrical conductivity by connecting Cu (copper) pads together).

[0372] 26 shows an example in which Cu-Cu direct bonding technology is used to bond conductive layer 341 and conductive layer 342, but the present invention is not limited to this. As shown in FIG. 27 , in display device 100G, conductive layer 341 and conductive layer 342 may be bonded via bump 347.

[0373] 27 , by providing a bump 347 between the conductive layer 341 and the conductive layer 342, the conductive layer 341 and the conductive layer 342 can be electrically connected. The bump 347 can be formed using a conductive material containing, for example, gold (Au), nickel (Ni), indium (In), tin (Sn), or the like. Alternatively, for example, solder may be used as the bump 347. An adhesive layer 348 may be provided between the insulating layer 345 and the insulating layer 346. When the bump 347 is provided, the insulating layer 335 and the insulating layer 336 may not be provided.

[0374] This embodiment mode can be combined with other embodiment modes as appropriate.

[0375] Embodiment 5 In this embodiment, a structural example of a transistor that can be applied to a display device of one embodiment of the present invention will be described. In particular, the case where a transistor containing silicon as a semiconductor in which a channel is formed will be described.

[0376] One embodiment of the present invention is a display device including a light-emitting device and a pixel circuit. The display device can achieve a full-color display device by including, for example, three types of sub-pixels that emit red (R), green (G), and blue (B) light, respectively.

[0377] It is preferable that all transistors included in a pixel circuit that drives a light-emitting device be transistors having silicon in a semiconductor layer in which a channel is formed. Examples of silicon include single-crystal silicon (single-crystal Si), polycrystalline silicon, and amorphous silicon. In particular, it is preferable to use a transistor having low-temperature polysilicon (LTPS) in the semiconductor layer (hereinafter also referred to as an LTPS transistor). LTPS transistors have high field-effect mobility and good frequency characteristics.

[0378] By using silicon transistors such as LTPS transistors, circuits that need to be driven at high frequencies (such as source driver circuits) can be built on the same substrate as the display unit, which simplifies the external circuits mounted on the display device and reduces component and mounting costs.

[0379] At least one of the transistors included in the pixel circuit preferably includes a transistor (hereinafter also referred to as an OS transistor) having a metal oxide (hereinafter also referred to as an oxide semiconductor) as a semiconductor in which a channel is formed. The OS transistor has significantly higher field-effect mobility than a transistor using amorphous silicon. Furthermore, the OS transistor has a significantly smaller source-drain leakage current in an off state (hereinafter also referred to as an off-state current), and can hold charge accumulated in a capacitor connected in series with the transistor for a long period of time. Furthermore, the use of an OS transistor can reduce the power consumption of a display device.

[0380] By using LTPS transistors for some of the transistors included in a pixel circuit and OS transistors for the other transistors, a display device with low power consumption and high driving capability can be realized. As a more preferred example, it is preferable to use OS transistors as transistors that function as switches for controlling conduction / non-conduction between wirings, and LTPS transistors as transistors that control current. Note that a structure in which both LTPS transistors and OS transistors are combined is sometimes referred to as LTPO. By using LTPO, a display panel with low power consumption and high driving capability can be realized.

[0381] For example, one of the transistors provided in the pixel circuit functions as a transistor for controlling a current flowing through a light-emitting device and can be called a driving transistor. One of the source and drain of the driving transistor is electrically connected to a pixel electrode of the light-emitting device. It is preferable to use an LTPS transistor as the driving transistor. This allows the current flowing through the light-emitting device in the pixel circuit to be increased.

[0382] On the other hand, another transistor provided in the pixel circuit functions as a switch for controlling pixel selection / non-selection and can also be called a selection transistor. The gate of the selection transistor is electrically connected to a gate line, and one of the source and drain is electrically connected to a source line (signal line). It is preferable to use an OS transistor as the selection transistor. This allows the gradation of a pixel to be maintained even when the frame frequency is significantly reduced (for example, 1 fps or less), and therefore power consumption can be reduced by stopping the driver when displaying a still image.

[0383] A more specific configuration example will be described below with reference to the drawings.

[0384] 28A shows a block diagram of the display device 10. The display device 10 includes a display unit 11, a drive circuit unit 12, a drive circuit unit 13, and the like.

[0385] The display unit 11 has a plurality of pixels 30 arranged in a matrix. Each pixel 30 has sub-pixels 21R, 21G, and 21B. Each of the sub-pixels 21R, 21G, and 21B has a light-emitting device that functions as a display device.

[0386] The pixel 30 is electrically connected to a wiring GL, a wiring SLR, a wiring SLG, and a wiring SLB. The wirings SLR, SLG, and SLB are each electrically connected to a driver circuit unit 12. The wiring GL is electrically connected to a driver circuit unit 13. The driver circuit unit 12 functions as a source line driver circuit (also referred to as a source driver), and the driver circuit unit 13 functions as a gate line driver circuit (also referred to as a gate driver). The wiring GL functions as a gate line, and the wirings SLR, SLG, and SLB function as source lines.

[0387] Sub-pixel 21R has a light-emitting device that emits red light. Sub-pixel 21G has a light-emitting device that emits green light. Sub-pixel 21B has a light-emitting device that emits blue light. This allows the display device 10 to display full color. Alternatively, pixel 30 may have sub-pixels that emit light of other colors. For example, pixel 30 may have a sub-pixel that emits white light or a sub-pixel that emits yellow light in addition to the above three sub-pixels.

[0388] The wiring GL is electrically connected to the sub-pixels 21R, 21G, and 21B arranged in the row direction (extension direction of the wiring GL). The wiring SLR, wiring SLG, and wiring SLB are electrically connected to the sub-pixels 21R, 21G, and 21B (not shown) arranged in the column direction (extension direction of the wiring SLR, etc.), respectively.

[0389] [Configuration Example of Pixel Circuit] Figure 28B shows an example of a circuit diagram of a pixel 21 that can be applied to the subpixels 21R, 21G, and 21B. The pixel 21 includes a transistor M1, a transistor M2, a transistor M3, a capacitor C1, and a light-emitting device EL. A wiring GL and a wiring SL are electrically connected to the pixel 21. The wiring SL corresponds to any one of the wirings SLR, SLG, and SLB shown in Figure 28A.

[0390] The transistor M1 has a gate electrically connected to a wiring GL, one of a source and a drain electrically connected to a wiring SL, and the other electrically connected to one electrode of a capacitor C1 and the gate of the transistor M2. The transistor M2 has one of a source and a drain electrically connected to a wiring AL, and the other of a source and a drain electrically connected to one electrode of a light-emitting device EL, the other electrode of the capacitor C1, and one of a source and a drain of the transistor M3. The transistor M3 has a gate electrically connected to a wiring GL, and the other of a source and a drain electrically connected to a wiring RL. The light-emitting device EL has the other electrode electrically connected to a wiring CL.

[0391] The wiring SL is supplied with a data potential D. The wiring GL is supplied with a selection signal. The selection signal includes a potential that turns on a transistor and a potential that turns off a transistor.

[0392] A reset potential is applied to the wiring RL. An anode potential is applied to the wiring AL. A cathode potential is applied to the wiring CL. In the pixel 21, the anode potential is higher than the cathode potential. The reset potential applied to the wiring RL can be a potential such that the potential difference between the reset potential and the cathode potential is smaller than the threshold voltage of the light-emitting device EL. The reset potential can be a potential higher than the cathode potential, the same as the cathode potential, or a potential lower than the cathode potential.

[0393] The transistors M1 and M3 function as switches. The transistor M2 functions as a transistor for controlling the current flowing through the light-emitting device EL. For example, it can be said that the transistor M1 functions as a selection transistor and the transistor M2 functions as a drive transistor.

[0394] Here, it is preferable that all of the transistors M1 to M3 be LTPS transistors. Alternatively, it is preferable that the transistors M1 and M3 be OS transistors and the transistor M2 be an LTPS transistor.

[0395] Alternatively, all of the transistors M1 to M3 may be OS transistors. In this case, one or more of the transistors included in the driver circuit portion 12 and the transistors included in the driver circuit portion 13 may be LTPS transistors, and the remaining transistors may be OS transistors. For example, OS transistors may be used as transistors provided in the display portion 11, and LTPS transistors may be used as transistors provided in the driver circuit portion 12 and the driver circuit portion 13.

[0396] As the OS transistor, a transistor including an oxide semiconductor for a semiconductor layer in which a channel is formed can be used. The semiconductor layer preferably contains, for example, indium, M (M is one or more 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), and zinc. In particular, M is preferably one or more selected from aluminum, gallium, yttrium, and tin. In particular, an oxide containing indium, gallium, and zinc (also referred to as IGZO) is preferably used for the semiconductor layer of the OS transistor. Alternatively, an oxide containing indium, tin, and zinc is preferably used. Alternatively, an oxide containing indium, gallium, tin, and zinc is preferably used.

[0397] A transistor using an oxide semiconductor, which has a wider band gap and a lower carrier density than silicon, can achieve an extremely small off-state current. Therefore, the small off-state current allows charge stored in a capacitor connected in series with the transistor to be held for a long period of time. Therefore, it is preferable to use transistors including oxide semiconductors for the transistors M1 and M3 connected in series with the capacitor C1. Using transistors including oxide semiconductors as the transistors M1 and M3 can prevent charge stored in the capacitor C1 from leaking through the transistor M1 or M3. Furthermore, because charge stored in the capacitor C1 can be held for a long period of time, a still image can be displayed for a long period of time without rewriting data in the pixel 21.

[0398] Note that although the transistors are shown as n-channel transistors in FIG. 28B, p-channel transistors can also be used.

[0399] Moreover, it is preferable that the transistors included in the pixel 21 are formed side by side on the same substrate.

[0400] As the transistor included in the pixel 21, a transistor having a pair of gates overlapping with each other with a semiconductor layer interposed therebetween can be used.

[0401] In a transistor having a pair of gates, when the pair of gates are electrically connected to each other and supplied with the same potential, the on-state current of the transistor is increased and the saturation characteristics are improved. A potential for controlling the threshold voltage of the transistor may be supplied to one of the pair of gates. Supplying a constant potential to one of the pair of gates can improve the stability of the electrical characteristics of the transistor. For example, one gate of the transistor may be electrically connected to a wiring to which a constant potential is supplied, or to its own source or drain.

[0402] 28C is an example of a pixel 21 in which the transistors M1 and M3 each have a pair of gates. The pair of gates of the transistors M1 and M3 are electrically connected. With this configuration, the period for writing data to the pixel 21 can be shortened.

[0403] 28D is an example in which a transistor having a pair of gates is used for the transistor M2 in addition to the transistors M1 and M3. The pair of gates of the transistor M2 are electrically connected. By using such a transistor for the transistor M2, the saturation characteristics are improved, which makes it easier to control the light emission luminance of the light-emitting device EL, thereby improving the display quality.

[0404] [Example of Transistor Structure] Hereinafter, an example of a cross-sectional structure of a transistor that can be applied to the display device will be described.

[0405] Configuration Example 1 FIG. 29A is a cross-sectional view including a transistor 410. FIG.

[0406] The transistor 410 is provided on the substrate 401 and has a semiconductor layer made of polycrystalline silicon. For example, the transistor 410 corresponds to the transistor M2 of the pixel 21. That is, Fig. 29A illustrates an example in which one of the source and the drain of the transistor 410 is electrically connected to the conductive layer 431 of the light-emitting device.

[0407] The transistor 410 includes a semiconductor layer 411, an insulating layer 412, a conductive layer 413, and the like. The semiconductor layer 411 includes a channel formation region 411i and a low-resistance region 411n. The semiconductor layer 411 includes silicon. The semiconductor layer 411 preferably includes polycrystalline silicon. A part of the insulating layer 412 functions as a gate insulating layer. A part of the conductive layer 413 functions as a gate electrode.

[0408] Note that the semiconductor layer 411 can also include a metal oxide (also referred to as an oxide semiconductor) that exhibits semiconductor characteristics. In this case, the transistor 410 can be called an OS transistor.

[0409] The low-resistance region 411n is a region containing an impurity element. For example, when the transistor 410 is an n-channel transistor, phosphorus, arsenic, or the like may be added to the low-resistance region 411n. On the other hand, when the transistor 410 is a p-channel transistor, boron, aluminum, or the like may be added to the low-resistance region 411n. Furthermore, in order to control the threshold voltage of the transistor 410, the above-mentioned impurities may be added to the channel formation region 411i.

[0410] An insulating layer 421 is provided over a substrate 401. A semiconductor layer 411 is provided over the insulating layer 421. An insulating layer 412 is provided to cover the semiconductor layer 411 and the insulating layer 421. A conductive layer 413 is provided over the insulating layer 412 so as to overlap with the semiconductor layer 411.

[0411] An insulating layer 422 is provided to cover the conductive layer 413 and the insulating layer 412. A conductive layer 414a and a conductive layer 414b are provided over the insulating layer 422. The conductive layer 414a and the conductive layer 414b are electrically connected to the low-resistance region 411n through openings provided in the insulating layer 422 and the insulating layer 412. A part of the conductive layer 414a functions as one of the source electrode and the drain electrode, and a part of the conductive layer 414b functions as the other of the source electrode and the drain electrode. An insulating layer 423 is provided to cover the conductive layer 414a, the conductive layer 414b, and the insulating layer 422.

[0412] A conductive layer 431 functioning as a pixel electrode is provided over the insulating layer 423. The conductive layer 431 is provided over the insulating layer 423 and is electrically connected to the conductive layer 414b in an opening provided in the insulating layer 423. Although not shown here, an EL layer and a common electrode can be stacked over the conductive layer 431.

[0413] 29B shows a transistor 410a having a pair of gate electrodes, which is different from the transistor 410a shown in FIG. 29A mainly in that a conductive layer 415 and an insulating layer 416 are included.

[0414] The conductive layer 415 is provided over the insulating layer 421. An insulating layer 416 is provided to cover the conductive layer 415 and the insulating layer 421. The semiconductor layer 411 is provided so that at least a channel formation region 411i overlaps with the conductive layer 415 with the insulating layer 416 interposed therebetween.

[0415] 29B , part of the conductive layer 413 functions as a first gate electrode, part of the conductive layer 415 functions as a second gate electrode, part of the insulating layer 412 functions as a first gate insulating layer, and part of the insulating layer 416 functions as a second gate insulating layer.

[0416] Here, when the first gate electrode and the second gate electrode are electrically connected, the conductive layer 413 and the conductive layer 415 may be electrically connected through openings provided in the insulating layers 412 and 416 in a region not shown. When the second gate electrode and the source or drain are electrically connected, the conductive layer 414a or the conductive layer 414b may be electrically connected to the conductive layer 415 through openings provided in the insulating layers 422, 412, and 416 in a region not shown.

[0417] 29A or 29B can be used. In this case, the transistor 410a may be used for all the transistors constituting the pixel 21, the transistor 410 may be used for all the transistors constituting the pixel 21, or the transistor 410 may be used for all the transistors constituting the pixel 21, or the transistor 410a and the transistor 410 may be used in combination.

[0418] [Structure Example 3] Hereinafter, a structure example including both a transistor in which silicon is used for a semiconductor layer and a transistor in which a metal oxide is used for a semiconductor layer will be described.

[0419] FIG. 29C shows a cross-sectional schematic diagram including transistor 410a and transistor 450.

[0420] The transistor 410a can be the same as in Structure Example 1. Note that although the transistor 410a is used in this example, a structure including the transistor 410 and the transistor 450 may be used, or a structure including all of the transistors 410, 410a, and 450 may be used.

[0421] The transistor 450 is a transistor in which a metal oxide is used for a semiconductor layer. The configuration shown in Fig. 29C is an example in which the transistor 450 corresponds to the transistor M1 of the pixel 21 and the transistor 410a corresponds to the transistor M2. That is, Fig. 29C shows an example in which one of the source and the drain of the transistor 410a is electrically connected to the conductive layer 431.

[0422] FIG. 29C shows an example in which the transistor 450 has a pair of gates.

[0423] The transistor 450 includes a conductive layer 455, an insulating layer 422, a semiconductor layer 451, an insulating layer 452, a conductive layer 453, and the like. Part of the conductive layer 453 functions as a first gate of the transistor 450, and part of the conductive layer 455 functions as a second gate of the transistor 450. In this case, part of the insulating layer 452 functions as a first gate insulating layer of the transistor 450, and part of the insulating layer 422 functions as a second gate insulating layer of the transistor 450.

[0424] The conductive layer 455 is provided over the insulating layer 412. The insulating layer 422 is provided to cover the conductive layer 455. The semiconductor layer 451 is provided over the insulating layer 422. The insulating layer 452 is provided to cover the semiconductor layer 451 and the insulating layer 422. The conductive layer 453 is provided over the insulating layer 452 and has a region overlapping with the semiconductor layer 451 and the conductive layer 455.

[0425] An insulating layer 426 is provided to cover the insulating layer 452 and the conductive layer 453. A conductive layer 454a and a conductive layer 454b are provided over the insulating layer 426. The conductive layer 454a and the conductive layer 454b are electrically connected to the semiconductor layer 451 through openings provided in the insulating layer 426 and the insulating layer 452. A part of the conductive layer 454a functions as one of the source electrode and the drain electrode, and a part of the conductive layer 454b functions as the other of the source electrode and the drain electrode. An insulating layer 423 is provided to cover the conductive layer 454a, the conductive layer 454b, and the insulating layer 426.

[0426] Here, the conductive layers 414a and 414b electrically connected to the transistor 410a are preferably formed by processing the same conductive film as the conductive layers 454a and 454b. Figure 29C shows a configuration in which the conductive layers 414a, 414b, 454a, and 454b are formed on the same surface (i.e., in contact with the top surface of the insulating layer 426) and contain the same metal element. In this case, the conductive layers 414a and 414b are electrically connected to the low-resistance region 411n through openings provided in the insulating layer 426, the insulating layer 452, the insulating layer 422, and the insulating layer 412. This is preferable because it simplifies the manufacturing process.

[0427] The conductive layer 413 functioning as the first gate electrode of the transistor 410a and the conductive layer 455 functioning as the second gate electrode of the transistor 450 are preferably formed by processing the same conductive film. In Figure 29C, the conductive layer 413 and the conductive layer 455 are formed on the same surface (i.e., in contact with the top surface of the insulating layer 412) and contain the same metal element. This is preferable because it simplifies the manufacturing process.

[0428] In Figure 29C, the insulating layer 452 functioning as the first gate insulating layer of the transistor 450 covers the end portion of the semiconductor layer 451. However, as in the transistor 450a shown in Figure 29D, the insulating layer 452 may be processed so that the top surface shape thereof matches or approximately matches the top surface shape of the conductive layer 453.

[0429] In this specification, the phrase "top surface shapes generally match" refers to the overlap of at least a portion of the contours between stacked layers. For example, this includes cases where the upper and lower layers are processed using the same mask pattern or a portion of the same mask pattern. However, strictly speaking, the contours may not overlap, and the upper layer may be located inside the lower layer, or outside the lower layer. In these cases, the phrase "top surface shapes generally match" also applies.

[0430] Note that, although an example is shown here in which the transistor 410a corresponds to the transistor M2 and is electrically connected to the pixel electrode, this is not limiting. For example, the transistor 450 or the transistor 450a may correspond to the transistor M2. In this case, the transistor 410a corresponds to the transistor M1, the transistor M3, or another transistor.

[0431] This embodiment mode can be combined with other embodiment modes as appropriate.

[0432] Embodiment 6 In this embodiment, a metal oxide (also referred to as an oxide semiconductor) that can be used for the OS transistor described in the above embodiment will be described.

[0433] The metal oxide preferably contains at least indium or zinc. It is particularly preferable that it contains indium and zinc. It is also preferable that it contains aluminum, gallium, yttrium, tin, or the like in addition to these. It may also contain one or more elements selected from boron, silicon, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, magnesium, cobalt, and the like.

[0434] The metal oxide can be formed by a sputtering method, a chemical vapor deposition method such as a metal organic chemical vapor deposition (MOCVD) method, or an atomic layer deposition method.

[0435] <Classification of Crystal Structure> Examples of the crystal structure of an oxide semiconductor include amorphous (including completely amorphous), c-axis-aligned crystalline line (CAAC), nanocrystalline line (nc), cloud-aligned composite (CAC), single crystal, and polycrystalline.

[0436] The crystalline structure of the film or substrate can be evaluated using an X-ray diffraction (XRD) spectrum. For example, it can be evaluated using an XRD spectrum obtained by a GIXD (Grazing-Incident XRD) measurement. The GIXD method is also called the thin film method or the Seemann-Bohlin method.

[0437] For example, in the case of a quartz glass substrate, the shape of the peak in the XRD spectrum is almost symmetrical. On the other hand, in the case of an IGZO film having a crystalline structure, the shape of the peak in the XRD spectrum is asymmetrical. The asymmetrical shape of the peak in the XRD spectrum clearly indicates the presence of crystals in the film or substrate. In other words, if the shape of the peak in the XRD spectrum is not symmetrical, the film or substrate cannot be said to be in an amorphous state.

[0438] The crystalline structure of the film or substrate can be evaluated by a diffraction pattern (also referred to as a nanobeam electron diffraction pattern) observed by nanobeam electron diffraction (NBED). For example, a halo is observed in the diffraction pattern of a quartz glass substrate, and it can be confirmed that the quartz glass is in an amorphous state. Furthermore, a spot-like pattern is observed in the diffraction pattern of an IGZO film formed at room temperature, rather than a halo. For this reason, it is estimated that the IGZO film formed at room temperature is neither crystalline nor amorphous, but is in an intermediate state, and it cannot be concluded that it is in an amorphous state.

[0439] <<Structure of Oxide Semiconductor>> Note that oxide semiconductors may be classified differently from the above when focusing on their structures. For example, oxide semiconductors are classified into single-crystal oxide semiconductors and other non-single-crystal oxide semiconductors. Examples of non-single-crystal oxide semiconductors include the above-mentioned CAAC-OS and nc-OS. Non-single-crystal oxide semiconductors include polycrystalline oxide semiconductors, pseudo-amorphous-like oxide semiconductors (a-like OSs), amorphous oxide semiconductors, and the like.

[0440] Here, the above-mentioned CAAC-OS, nc-OS, and a-like OS will be described in detail.

[0441] [CAAC-OS] A CAAC-OS is an oxide semiconductor having multiple crystalline regions, each with its c-axis aligned in a specific direction. The specific direction refers to the thickness direction of the CAAC-OS film, the normal direction to the surface where the CAAC-OS film is formed, or the normal direction to the surface of the CAAC-OS film. A crystalline region is a region having periodic atomic arrangement. If the atomic arrangement is considered as a lattice arrangement, a crystalline region is also a region with a uniform lattice arrangement. Furthermore, a CAAC-OS has a region where multiple crystalline regions are connected in the a-b plane direction, and the region may have distortion. Note that distortion refers to a portion where the lattice arrangement changes between a region with a uniform lattice arrangement and a region with another uniform lattice arrangement in a region where multiple crystalline regions are connected. In other words, a CAAC-OS is an oxide semiconductor whose c-axes are aligned and whose orientation is not clearly aligned in the a-b plane direction.

[0442] Each of the multiple crystalline regions is composed of one or more minute crystals (crystals with a maximum diameter of less than 10 nm). When a crystalline region is composed of a single minute crystal, the maximum diameter of the crystalline region is less than 10 nm. When a crystalline region is composed of many minute crystals, the size of the crystalline region may be several tens of nanometers.

[0443] In an In-M-Zn oxide (wherein the element M is one or more elements selected from aluminum, gallium, yttrium, tin, titanium, and the like), the CAAC-OS tends to have a layered crystal structure (also referred to as a layered structure) in which a layer containing indium (In) and oxygen (hereinafter referred to as an In layer) and a layer containing the element M, zinc (Zn), and oxygen (hereinafter referred to as an (M, Zn) layer) are stacked. Note that indium and the element M are mutually substituted. Therefore, the (M, Zn) layer may contain indium. The In layer may contain the element M. The In layer may contain Zn. The layered structure is observed as a lattice image in a high-resolution transmission electron microscope (TEM) image, for example.

[0444] When a CAAC-OS film is subjected to structural analysis using an XRD apparatus, for example, a peak indicating c-axis orientation is detected at or near 2θ = 31° in out-of-plane XRD measurement using θ / 2θ scanning. Note that the position of the peak indicating c-axis orientation (the value of 2θ) may vary depending on the type and composition of the metal elements constituting the CAAC-OS.

[0445] For example, multiple bright spots are observed in the electron diffraction pattern of a CAAC-OS film, and the spots are observed at positions that are point-symmetric with respect to a spot of an incident electron beam that has passed through the sample (also referred to as a direct spot).

[0446] When a crystalline region is observed from the specific direction, the lattice arrangement in the crystalline region is basically a hexagonal lattice, but the unit cell is not necessarily a regular hexagon and may be a non-regular hexagon. The distortion may have a pentagonal, heptagonal, or other lattice arrangement. In the CAAC-OS, no clear grain boundary can be identified even near the distortion. This indicates that the distortion in the lattice arrangement suppresses the formation of grain boundaries. This is thought to be because the CAAC-OS can tolerate distortion due to the lack of close-packed arrangement of oxygen atoms in the a-b plane and the change in interatomic bond distance caused by metal atom substitution.

[0447] Note that a crystal structure in which clear grain boundaries are observed is called polycrystalline. The grain boundaries act as recombination centers, and are likely to trap carriers, resulting in a decrease in the on-state current of a transistor and a decrease in field-effect mobility. Therefore, CAAC-OS, in which clear grain boundaries are not observed, is one of the crystalline oxides having a crystal structure suitable for a semiconductor layer of a transistor. Note that a structure containing Zn is preferable for forming a CAAC-OS. For example, In—Zn oxide and In—Ga—Zn oxide are suitable because they can suppress the generation of grain boundaries more effectively than In oxide.

[0448] CAAC-OS is an oxide semiconductor with high crystallinity and no clear crystal grain boundaries. Therefore, it can be said that the CAAC-OS is less susceptible to a decrease in electron mobility due to crystal grain boundaries. Furthermore, since the crystallinity of an oxide semiconductor can be reduced by the inclusion of impurities, the formation of defects, or the like, the CAAC-OS can also be said to be an oxide semiconductor with few impurities and defects (such as oxygen vacancies). Therefore, an oxide semiconductor having a CAAC-OS has stable physical properties. Therefore, an oxide semiconductor having a CAAC-OS is heat-resistant and highly reliable. Furthermore, the CAAC-OS is stable even against high temperatures (so-called thermal budget) in the manufacturing process. Therefore, the use of a CAAC-OS in an OS transistor can increase the flexibility of the manufacturing process.

[0449] [nc-OS] The nc-OS has periodic atomic arrangement in a microscopic region (e.g., a region of 1 nm to 10 nm, particularly a region of 1 nm to 3 nm). In other words, the nc-OS has microcrystals. Note that the size of the microcrystals is, for example, 1 nm to 10 nm, particularly 1 nm to 3 nm, and therefore the microcrystals are also called nanocrystals. Furthermore, the nc-OS does not exhibit regularity in the crystal orientation between different nanocrystals. Therefore, no orientation is observed throughout the film. Therefore, depending on the analysis method, the nc-OS may be indistinguishable from an a-like OS or an amorphous oxide semiconductor. For example, when a structural analysis of an nc-OS film is performed using an XRD apparatus, no peak indicating crystallinity is detected in out-of-plane XRD measurement using θ / 2θ scanning. When an nc-OS film is subjected to electron diffraction (also referred to as selected-area electron diffraction) using an electron beam with a probe diameter larger than that of a nanocrystal (e.g., 50 nm or more), a diffraction pattern resembling a halo pattern is observed. On the other hand, when an nc-OS film is subjected to electron diffraction (also referred to as nanobeam electron diffraction) using an electron beam with a probe diameter close to or smaller than that of a nanocrystal (e.g., 1 nm to 30 nm), an electron diffraction pattern in which multiple spots are observed within a ring-shaped region centered on a direct spot may be obtained.

[0450] [a-Like OS] The a-like OS is an oxide semiconductor having a structure between the nc-OS and the amorphous oxide semiconductor. The a-like OS has a pore or low-density region. That is, the a-like OS has lower crystallinity than the nc-OS and the CAAC-OS. Furthermore, the a-like OS has a higher hydrogen concentration in the film than the nc-OS and the CAAC-OS.

[0451] <<Structure of Oxide Semiconductor>> Next, the above-described CAC-OS will be described in detail. Note that the CAC-OS relates to a material structure.

[0452] [CAC-OS] CAC-OS is, for example, a material in which elements constituting a metal oxide are unevenly distributed in a size of 0.5 nm to 10 nm, preferably 1 nm to 3 nm, or in the vicinity thereof. Note that hereinafter, a state in which one or more metal elements are unevenly distributed in a metal oxide and regions containing the metal elements are mixed in a size of 0.5 nm to 10 nm, preferably 1 nm to 3 nm, or in the vicinity thereof, is also referred to as a mosaic or patch state.

[0453] Furthermore, the CAC-OS has a mosaic structure in which a material is separated into a first region and a second region, and the first region is distributed throughout the film (hereinafter also referred to as a cloud structure). That is, the CAC-OS is a composite metal oxide having a structure in which the first region and the second region are mixed.

[0454] Here, the atomic ratios of In, Ga, and Zn to the metal elements constituting the CAC-OS in the In—Ga—Zn oxide are denoted as [In], [Ga], and [Zn], respectively. For example, in the CAC-OS in the In—Ga—Zn oxide, the first region is a region where [In] is larger than [In] in the composition of the CAC-OS film. The second region is a region where [Ga] is larger than [Ga] in the composition of the CAC-OS film. Alternatively, for example, the first region is a region where [In] is larger than [In] in the second region and [Ga] is smaller than [Ga] in the second region. The second region is a region where [Ga] is larger than [Ga] in the first region and [In] is smaller than [In] in the first region.

[0455] Specifically, the first region is a region whose main component is indium oxide, indium zinc oxide, or the like. The second region is a region whose main component is gallium oxide, gallium zinc oxide, or the like. In other words, the first region can be referred to as a region whose main component is In. The second region can be referred to as a region whose main component is Ga.

[0456] It should be noted that there are cases where a clear boundary between the first region and the second region cannot be observed.

[0457] Furthermore, CAC-OS in In—Ga—Zn oxide refers to a structure in which a mosaic of regions containing Ga as the main component and regions containing In as the main component are randomly arranged in a material composition containing In, Ga, Zn, and O. Therefore, it is presumed that CAC-OS has a structure in which metal elements are distributed nonuniformly.

[0458] The CAC-OS can be formed by sputtering without heating the substrate. When the CAC-OS is formed by sputtering, one or more of an inert gas (typically argon), oxygen gas, and nitrogen gas may be used as the deposition gas. The lower the flow rate of oxygen gas relative to the total flow rate of deposition gas during deposition, the more preferable it is. For example, the flow rate of oxygen gas relative to the total flow rate of deposition gas during deposition is preferably 0% or more and less than 30%, and more preferably 0% or more and 10% or less.

[0459] Furthermore, for example, in the case of CAC-OS in an In—Ga—Zn oxide, EDX mapping obtained using energy dispersive X-ray spectroscopy (EDX) can confirm that the CAC-OS has a structure in which a region containing In as a main component (first region) and a region containing Ga as a main component (second region) are unevenly distributed and mixed.

[0460] Here, the first region has higher conductivity than the second region. That is, the flow of carriers through the first region causes the metal oxide to exhibit conductivity. Therefore, the first region is distributed in a cloud-like manner in the metal oxide, thereby achieving a high field-effect mobility (μ).

[0461] On the other hand, the second region has higher insulating properties than the first region. That is, the second region is distributed in the metal oxide, thereby suppressing leakage current.

[0462] Therefore, when a CAC-OS is used in a transistor, the conductivity due to the first region and the insulating property due to the second region act complementarily, thereby providing the CAC-OS with a switching function (a function of turning on / off). In other words, a CAC-OS has a conductive function in a part of the material and an insulating function in a part of the material, and the entire material functions as a semiconductor. By separating the conductive function and the insulating function, both functions can be maximized. Therefore, by using a CAC-OS in a transistor, a high on-current (I ｏｎ ), high field-effect mobility (μ), and good switching behavior can be achieved.

[0463] Furthermore, a transistor using the CAC-OS has high reliability, and therefore, the CAC-OS is ideal for various semiconductor devices such as display devices.

[0464] Oxide semiconductors have a variety of structures, each of which has different characteristics. The oxide semiconductor of one embodiment of the present invention may include two or more of an amorphous oxide semiconductor, a polycrystalline oxide semiconductor, an a-like OS, a CAC-OS, an nc-OS, and a CAAC-OS.

[0465] <Transistor Having Oxide Semiconductor> Next, a case where the oxide semiconductor is used for a transistor will be described.

[0466] By using the oxide semiconductor for a transistor, a transistor with high field-effect mobility and high reliability can be realized.

[0467] For the transistor, an oxide semiconductor having a low carrier concentration is preferably used. For example, the carrier concentration of the oxide semiconductor is 1×10 １７ cm −３ Below 1 × 10, preferably １５ cm −３ More preferably, 1×10 １３ cm −３ or less, more preferably 1 × 10 １１ cm −３ More preferably, 1×10１０ cm −３ is less than 1×10 −９ cm −３ That is all. Note that in order to reduce the carrier concentration of an oxide semiconductor film, the impurity concentration in the oxide semiconductor film may be reduced to reduce the density of defect states. In this specification and the like, a semiconductor having a low impurity concentration and a low density of defect states is referred to as a highly purified intrinsic or substantially highly purified intrinsic oxide semiconductor. Note that an oxide semiconductor having a low carrier concentration may also be referred to as a highly purified intrinsic or substantially highly purified intrinsic oxide semiconductor.

[0468] Furthermore, a highly purified intrinsic or substantially highly purified intrinsic oxide semiconductor film has a low density of defect states, and therefore the density of trap states may also be low.

[0469] Furthermore, charges trapped in the trap states of an oxide semiconductor take a long time to disappear and may behave like fixed charges. Therefore, a transistor in which a channel formation region is formed in an oxide semiconductor with a high density of trap states may have unstable electrical characteristics.

[0470] Therefore, in order to stabilize the electrical characteristics of a transistor, it is effective to reduce the impurity concentration in the oxide semiconductor. Furthermore, in order to reduce the impurity concentration in the oxide semiconductor, it is preferable to also reduce the impurity concentration in the adjacent film. Examples of impurities include hydrogen, nitrogen, alkali metals, alkaline earth metals, iron, nickel, and silicon.

[0471] <Impurities> Here, the influence of each impurity in an oxide semiconductor will be described.

[0472] When an oxide semiconductor contains silicon or carbon, which is one of Group 14 elements, defect levels are formed in the oxide semiconductor. Therefore, the concentration of silicon or carbon in the oxide semiconductor and the concentration of silicon or carbon near the interface with the oxide semiconductor (concentration obtained by secondary ion mass spectrometry (SIMS)) are set to 2×10 １８ atoms / cm ３ Below 2 × 10, preferably １７ atoms / cm３ The following applies.

[0473] Furthermore, when an oxide semiconductor contains an alkali metal or an alkaline earth metal, defect levels are formed and carriers are generated in some cases. Therefore, a transistor using an oxide semiconductor containing an alkali metal or an alkaline earth metal is likely to have normally-on characteristics. For this reason, when the concentration of the alkali metal or the alkaline earth metal in the oxide semiconductor obtained by SIMS is 1×10 １８ atoms / cm ３ Below 2 × 10, preferably １６ atoms / cm ３ Do the following:

[0474] Furthermore, when nitrogen is contained in an oxide semiconductor, electrons serving as carriers are generated, the carrier concentration increases, and the semiconductor is likely to become n-type. As a result, a transistor using an oxide semiconductor containing nitrogen as a semiconductor tends to have normally-on characteristics. Alternatively, when nitrogen is contained in an oxide semiconductor, trap states may be formed. As a result, the electrical characteristics of the transistor may become unstable. For this reason, the nitrogen concentration in the oxide semiconductor obtained by SIMS is set to 5×10 １９ atoms / cm ３ Less than 5×10 １８ atoms / cm ３ or less, more preferably 1 × 10 １８ atoms / cm ３ or less, more preferably 5 × 10 １７ atoms / cm ３ Do the following:

[0475] Furthermore, hydrogen contained in an oxide semiconductor may react with oxygen bonded to a metal atom to form water, which may form an oxygen vacancy. Hydrogen entering the oxygen vacancy may generate electrons as carriers. Furthermore, some of the hydrogen may bond with oxygen bonded to a metal atom to generate electrons as carriers. Therefore, a transistor using an oxide semiconductor containing hydrogen is likely to have normally-on characteristics. Therefore, it is preferable to reduce hydrogen in the oxide semiconductor as much as possible. Specifically, the hydrogen concentration in the oxide semiconductor measured by SIMS is 1×10 ２０ atoms / cm ３ less than 1×10 １９ atoms / cm ３ less than 5×10 １８ atoms / cm ３ less than 1×10 １８ atoms / cm ３ Make it less than.

[0476] When an oxide semiconductor with sufficiently reduced impurities is used for a channel formation region of a transistor, stable electrical characteristics can be obtained.

[0477] This embodiment mode can be combined with other embodiment modes as appropriate.

[0478] Embodiment 7 In this embodiment, electronic devices of one embodiment of the present invention will be described with reference to FIGS. 30A to 34G.

[0479] The electronic devices of this embodiment include the display device of one embodiment of the present invention in their display portions. The display device of one embodiment of the present invention can easily achieve high definition and high resolution. Therefore, the display device of one embodiment of the present invention can be used in the display portions of various electronic devices.

[0480] Examples of electronic devices include electronic devices with relatively large screens such as television sets, desktop or notebook personal computers, computer monitors, digital signage, large game machines such as pachinko machines, as well as digital cameras, digital video cameras, digital photo frames, mobile phones, portable game machines, personal digital assistants, and sound playback devices.

[0481] In particular, the display device of one embodiment of the present invention can be suitably used in electronic devices having a relatively small display area because it can increase the resolution. Examples of such electronic devices include wristwatch-type and bracelet-type information terminals (wearable devices), and head-mounted wearable devices such as VR devices such as head-mounted displays, AR glasses-type devices, and MR devices.

[0482] The display device of one embodiment of the present invention preferably has an extremely high resolution such as HD (1280 × 720 pixels), FHD (1920 × 1080 pixels), WQHD (2560 × 1440 pixels), WQXGA (2560 × 1600 pixels), 4K (3840 × 2160 pixels), or 8K (7680 × 4320 pixels). A resolution of 4K, 8K, or higher is particularly preferable. Furthermore, the pixel density (resolution) of the display device of one embodiment of the present invention is preferably 100 ppi or higher, more preferably 300 ppi or higher, more preferably 500 ppi or higher, more preferably 1000 ppi or higher, more preferably 2000 ppi or higher, more preferably 3000 ppi or higher, more preferably 5000 ppi or higher, and even more preferably 7000 ppi or higher. By using a display device having either or both of high resolution and high definition, it is possible to further enhance the sense of realism and depth in electronic devices for personal use, such as portable or home use. Furthermore, the screen ratio (aspect ratio) of the display device of one embodiment of the present invention is not particularly limited. For example, the display device can support various screen ratios, such as 1:1 (square), 4:3, 16:9, and 16:10.

[0483] The electronic device of this embodiment may have a sensor (including a function to measure force, displacement, position, velocity, acceleration, angular velocity, rotation speed, distance, light, liquid, magnetism, temperature, chemical substance, sound, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, gradient, vibration, odor, or infrared rays).

[0484] The electronic device of the present embodiment can have various functions, such as a function to display various information (still images, videos, text images, etc.) on a display unit, a touch panel function, a function to display a calendar, date, time, etc., a function to execute various software (programs), a wireless communication function, a function to read out programs or data recorded on a recording medium, etc.

[0485] 30A, 30B, 31A, and 31B, examples of wearable devices that can be worn on the head will be described. These wearable devices have one or both of a function to display AR content and a function to display VR content. Note that these wearable devices may also have a function to display SR (Substitional Reality) or MR (Mixed Reality) content in addition to AR and VR. By having an electronic device have the function to display content such as AR, VR, SR, and MR, it is possible to enhance the user's sense of immersion.

[0486] The electronic device 700A shown in FIG. 30A and the electronic device 700B shown in FIG. 30B each have a pair of display panels 751, a pair of housings 721, a communication unit (not shown), a pair of mounting units 723, a control unit (not shown), an imaging unit (not shown), a pair of optical members 753, a frame 757, and a pair of nose pads 758.

[0487] The display device of one embodiment of the present invention can be applied to the display panel 751. Therefore, the electronic device can provide an extremely high-definition display.

[0488] The electronic device 700A and the electronic device 700B can each project an image displayed on the display panel 751 onto a display area 756 of the optical member 753. Because the optical member 753 is translucent, the user can see the image displayed in the display area superimposed on a transmitted image visually recognized through the optical member 753. Therefore, the electronic device 700A and the electronic device 700B are each electronic devices capable of AR display.

[0489] Electronic device 700A and electronic device 700B may be provided with a camera capable of capturing an image in front of them as an imaging unit. Furthermore, electronic device 700A and electronic device 700B may each be provided with an acceleration sensor such as a gyro sensor, thereby detecting the orientation of the user's head and displaying an image corresponding to that orientation in display area 756.

[0490] The communication unit has a wireless communication device, and can supply a video signal, etc. Instead of or in addition to the wireless communication device, a connector to which a cable through which a video signal and a power supply potential are supplied may be provided.

[0491] Furthermore, the electronic device 700A and the electronic device 700B are provided with batteries, which can be charged wirelessly and / or by wire.

[0492] The housing 721 may be provided with a touch sensor module. The touch sensor module has a function of detecting a touch on the outer surface of the housing 721. The touch sensor module can detect a tap operation or a slide operation by the user and perform various processes. For example, a tap operation can perform a process such as pausing or resuming a video, and a slide operation can perform a process such as fast-forwarding or fast-rewinding. Furthermore, providing a touch sensor module on each of the two housings 721 can expand the range of operations.

[0493] Various touch sensors can be used as the touch sensor module. For example, various types of touch sensors can be used, such as a capacitance type, a resistive film type, an infrared type, an electromagnetic induction type, a surface acoustic wave type, and an optical type. In particular, it is preferable to use a capacitance type or an optical type sensor in the touch sensor module.

[0494] When an optical touch sensor is used, a photoelectric conversion device (also called a photoelectric conversion element) can be used as the light receiving device (also called a light receiving element). The active layer of the photoelectric conversion device can be made of either or both of an inorganic semiconductor and an organic semiconductor.

[0495] The electronic device 800A shown in Figure 31A and the electronic device 800B shown in Figure 31B each have a pair of display units 820, a housing 821, a communication unit 822, a pair of mounting units 823, a control unit 824, a pair of imaging units 825, and a pair of lenses 832.

[0496] The display device of one embodiment of the present invention can be applied to the display portion 820. Therefore, an electronic device capable of displaying images with extremely high definition can be provided. This allows a user to feel a high sense of immersion.

[0497] The display unit 820 is provided inside the housing 821 at a position that can be viewed through the lens 832. In addition, by displaying different images on the pair of display units 820, it is possible to perform three-dimensional display using parallax.

[0498] The electronic device 800A and the electronic device 800B can be said to be electronic devices for VR. A user wearing the electronic device 800A or the electronic device 800B can view an image displayed on the display unit 820 through the lens 832.

[0499] It is preferable that electronic device 800A and electronic device 800B each have a mechanism that can adjust the left and right positions of lens 832 and display unit 820 so that they are optimally positioned according to the position of the user's eyes. It is also preferable that electronic device 800A and electronic device 800B each have a mechanism that can adjust the focus by changing the distance between lens 832 and display unit 820.

[0500] The mounting unit 823 allows the user to wear the electronic device 800A or the electronic device 800B on the head. Note that, in Fig. 31A and other figures, the mounting unit 823 is shaped like the temples of glasses (also called joints or temples), but is not limited to this. The mounting unit 823 may be shaped like a helmet or a band, for example, as long as it can be worn by the user.

[0501] The imaging unit 825 has a function of acquiring external information. Data acquired by the imaging unit 825 can be output to the display unit 820. An image sensor can be used for the imaging unit 825. Furthermore, multiple cameras may be provided to support multiple angles of view, such as telephoto and wide-angle.

[0502] Although an example including the imaging unit 825 is shown here, a distance measuring sensor (hereinafter also referred to as a detection unit) capable of measuring the distance to an object may be provided. That is, the imaging unit 825 is one aspect of the detection unit. As the detection unit, for example, an image sensor or a range image sensor such as a LIDAR (Light Detection and Ranging) can be used. By using an image obtained by the camera and an image obtained by the range image sensor, more information can be obtained, enabling more accurate gesture operations.

[0503] The electronic device 800A may have a vibration mechanism that functions as a bone conduction earphone. For example, a configuration having such a vibration mechanism can be applied to one or more of the display unit 820, the housing 821, and the wearing unit 823. This allows a user to enjoy video and audio simply by wearing the electronic device 800A, without the need for separate audio equipment such as headphones, earphones, or speakers.

[0504] The electronic device 800A and the electronic device 800B may each have an input terminal to which a cable can be connected for supplying a video signal from a video output device or the like and power for charging a battery provided in the electronic device.

[0505] The electronic device of one embodiment of the present invention may have a function of wireless communication with an earphone 750. The earphone 750 includes a communication unit (not shown) and has a wireless communication function. The earphone 750 can receive information (e.g., audio data) from the electronic device through the wireless communication function. For example, an electronic device 700A shown in FIG. 30A has a function of transmitting information to the earphone 750 through the wireless communication function. Furthermore, for example, an electronic device 800A shown in FIG. 31A has a function of transmitting information to the earphone 750 through the wireless communication function.

[0506] The electronic device may also have an earphone unit. Electronic device 700B shown in Fig. 30B has earphone unit 727. For example, earphone unit 727 and the control unit may be configured to be connected to each other by wire. Part of the wiring connecting earphone unit 727 and the control unit may be disposed inside housing 721 or attachment unit 723.

[0507] Similarly, electronic device 800B shown in Fig. 31B has earphone unit 827. For example, earphone unit 827 and control unit 824 can be configured to be connected to each other by wire. Part of the wiring connecting earphone unit 827 and control unit 824 may be disposed inside housing 821 or wearing unit 823. Furthermore, earphone unit 827 and wearing unit 823 may have magnets. This allows earphone unit 827 to be fixed to wearing unit 823 by magnetic force, which is preferable as it makes storage easier.

[0508] The electronic device may have an audio output terminal to which earphones or headphones can be connected. The electronic device may also have one or both of an audio input terminal and an audio input mechanism. For example, a sound collection device such as a microphone can be used as the audio input mechanism. By having the audio input mechanism, the electronic device may be endowed with the functionality of a so-called headset.

[0509] As described above, as electronic devices of one embodiment of the present invention, both glasses-type devices (such as the electronic devices 700A and 700B) and goggle-type devices (such as the electronic devices 800A and 800B) are suitable.

[0510] Furthermore, the electronic device of one embodiment of the present invention can transmit information to the earphone by wire or wirelessly.

[0511] The electronic device 6500 shown in FIG. 32A is a portable information terminal that can be used as a smartphone.

[0512] The electronic device 6500 includes a housing 6501, a display portion 6502, a power button 6503, a button 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.

[0513] The display device of one embodiment of the present invention can be applied to the display portion 6502 .

[0514] FIG. 32B is a schematic cross-sectional view including the end of the housing 6501 on the microphone 6506 side.

[0515] A light-transmitting protective member 6510 is provided on the display surface side of the housing 6501, and a display panel 6511, optical members 6512, a touch sensor panel 6513, a printed circuit board 6517, a battery 6518, etc. are arranged in the space surrounded by the housing 6501 and the protective member 6510.

[0516] A display panel 6511, an optical member 6512, and a touch sensor panel 6513 are fixed to the protective member 6510 by adhesive layers (not shown).

[0517] In a region outside the display portion 6502, a part of the display panel 6511 is folded back, and an FPC 6515 is connected to the folded back part. An IC 6516 is mounted on the FPC 6515. The FPC 6515 is connected to a terminal provided on a printed circuit board 6517.

[0518] The flexible display of one embodiment of the present invention can be applied to the display panel 6511. Therefore, an extremely lightweight electronic device can be realized. In addition, since the display panel 6511 is extremely thin, a large-capacity battery 6518 can be mounted thereon while keeping the thickness of the electronic device small. Furthermore, by folding back a part of the display panel 6511 and arranging a connection portion with the FPC 6515 on the back side of the pixel portion, an electronic device with a narrow frame can be realized.

[0519] 33A shows an example of a television set. A television set 7100 has a display portion 7000 built into a housing 7101. Here, the housing 7101 is supported by a stand 7103.

[0520] The display device of one embodiment of the present invention can be applied to the display portion 7000 .

[0521] 33A can be operated using operation switches provided on the housing 7101 and a separate remote control 7111. Alternatively, the display portion 7000 may be provided with a touch sensor, and the television set 7100 may be operated by touching the display portion 7000 with a finger or the like. The remote control 7111 may have a display portion that displays information output from the remote control 7111. Using operation keys or a touch panel provided on the remote control 7111, the channel and volume can be controlled, and an image displayed on the display portion 7000 can be controlled.

[0522] The television device 7100 is configured to include a receiver, a modem, and the like. The receiver can receive general television broadcasts. Furthermore, by connecting to a wired or wireless communication network via the modem, it is possible to perform one-way (from a sender to a receiver) or two-way (between a sender and a receiver, or between receivers, etc.) information communication.

[0523] 33B shows an example of a laptop personal computer 7200. The laptop personal computer 7200 includes a housing 7211, a keyboard 7212, a pointing device 7213, an external connection port 7214, and the like. The housing 7211 includes a display portion 7000.

[0524] The display device of one embodiment of the present invention can be applied to the display portion 7000 .

[0525] 33C and 33D show an example of digital signage.

[0526] 33C includes a housing 7301, a display portion 7000, and a speaker 7303. The digital signage 7300 may further include an LED lamp, operation keys (including a power switch or an operation switch), a connection terminal, various sensors, a microphone, and the like.

[0527] 33D shows a digital signage 7400 attached to a cylindrical pillar 7401. The digital signage 7400 has a display unit 7000 provided along the curved surface of the pillar 7401.

[0528] 33C and 33D, the display device of one embodiment of the present invention can be applied to the display portion 7000.

[0529] The larger the display unit 7000, the more information can be provided at one time. Also, the larger the display unit 7000, the more easily it will attract people's attention, which can increase the advertising effectiveness of, for example, advertisements.

[0530] Applying a touch panel to the display unit 7000 is preferable because it not only displays images or videos on the display unit 7000 but also allows the user to intuitively operate it. Furthermore, when used to provide information such as route information or traffic information, the intuitive operation can improve usability.

[0531] 33C and 33D , the digital signage 7300 or the digital signage 7400 is preferably capable of wirelessly linking with an information terminal 7311 or an information terminal 7411 such as a smartphone carried by a user. For example, advertising information displayed on the display unit 7000 can be displayed on the screen of the information terminal 7311 or the information terminal 7411. By operating the information terminal 7311 or the information terminal 7411, the display on the display unit 7000 can be switched.

[0532] Furthermore, the digital signage 7300 or the digital signage 7400 can be made to run a game using the screen of the information terminal 7311 or the information terminal 7411 as an operation means (controller), thereby allowing an unspecified number of users to simultaneously participate in and enjoy the game.

[0533] The electronic device shown in Figures 34A to 34G has a housing 9000, a display unit 9001, a speaker 9003, operation keys 9005 (including a power switch or an operation switch), a connection terminal 9006, a sensor 9007 (including a function to measure force, displacement, position, speed, acceleration, angular velocity, rotation speed, distance, light, liquid, magnetism, temperature, chemical substance, sound, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, gradient, vibration, odor or infrared rays), a microphone 9008, etc.

[0534] The electronic devices shown in Figures 34A to 34G have various functions. For example, they may have a function to display various information (still images, videos, text images, etc.) on a display unit, a touch panel function, a function to display a calendar, date, or time, a function to control processing using various software (programs), a wireless communication function, a function to read and process programs or data recorded on a recording medium, etc. Note that the functions of the electronic devices are not limited to these, and they may have various other functions. The electronic devices may have multiple display units. Furthermore, the electronic devices may have a function to include a camera or the like to capture still images or videos and store them on a recording medium (external or built-in to the camera), a function to display the captured images on a display unit, etc.

[0535] Details of the electronic device shown in Figures 34A to 34G will be described below.

[0536] FIG. 34A is a perspective view showing a mobile information terminal 9101. The mobile information terminal 9101 can be used as, for example, a smartphone. Note that the mobile information terminal 9101 may be provided with a speaker 9003, a connection terminal 9006, a sensor 9007, and the like. The mobile information terminal 9101 can display text and image information on multiple surfaces. FIG. 34A shows an example in which three icons 9050 are displayed. Information 9051, indicated by a dashed rectangle, can also be displayed on another surface of the display unit 9001. Examples of the information 9051 include notifications of incoming emails, SNS (Social Networking Service), and phone calls, the title of emails or SNS messages, the sender's name, the date and time, the remaining battery level, and signal strength. Alternatively, an icon 9050 or the like may be displayed in the position where the information 9051 is displayed.

[0537] 34B is a perspective view showing the mobile information terminal 9102. The mobile information terminal 9102 has a function of displaying information on three or more surfaces of the display unit 9001. Here, an example is shown in which information 9052, information 9053, and information 9054 are displayed on different surfaces. For example, a user can check information 9053 displayed in a position that can be observed from above the mobile information terminal 9102 while the mobile information terminal 9102 is placed in a breast pocket of clothes. The user can check the display without taking the mobile information terminal 9102 out of the pocket and decide, for example, whether to answer a call.

[0538] 34C is a perspective view showing a tablet terminal 9103. The tablet terminal 9103 is capable of executing various applications such as mobile phone calls, e-mail, text browsing and creation, music playback, internet communication, and computer games, for example. The tablet terminal 9103 has a display unit 9001, a camera 9002, a microphone 9008, and a speaker 9003 on the front side of a housing 9000, operation keys 9005 as operation buttons on the left side of the housing 9000, and a connection terminal 9006 on the bottom.

[0539] FIG. 34D is a perspective view showing a wristwatch-type mobile information terminal 9200. The mobile information terminal 9200 can be used as, for example, a smart watch (registered trademark). The display surface of the display unit 9001 is curved, and display can be performed along the curved display surface. The mobile information terminal 9200 can also perform hands-free calling by communicating with, for example, a wirelessly capable headset. The mobile information terminal 9200 can also perform data transmission and charging with another information terminal through a connection terminal 9006. Note that charging may be performed by wireless power supply.

[0540] 34E to 34G are perspective views showing a foldable mobile information terminal 9201. Also, FIG. 34E is a perspective view of the mobile information terminal 9201 in an unfolded state, FIG. 34G is a perspective view of the mobile information terminal 9201 in a folded state, and FIG. 34F is a perspective view of a state in the process of changing from one of FIG. 34E and FIG. 34G to the other. The mobile information terminal 9201 is highly portable when folded, and has a seamless, wide display area when unfolded, providing excellent visibility of the display. The display portion 9001 of the mobile information terminal 9201 is supported by three housings 9000 connected by hinges 9055. For example, the display portion 9001 can be bent with a curvature radius of 0.1 mm or more and 150 mm or less.

[0541] This embodiment mode can be combined with other embodiment modes as appropriate.

[0542] AL: wiring, CL: wiring, GL: wiring, RL: wiring, SL: wiring, SLB: wiring, SLG: wiring, SLR: wiring, 10: display device, 11: display unit, 12: drive circuit unit, 13: drive circuit unit, 21: pixel, 21R: sub-pixel, 21G: sub-pixel, 21B: sub-pixel, 30: pixel, 100: display device, 100A: display device, 100B: display device, 100C: display device, 100D: display device, 100E: display device, 100F: display device, 100G: display device, 101: layer, 103: EL layer, 103a: EL layer, 103b: EL layer, 103c: EL layer, 110: pixel, 11 0a: sub-pixel, 110b: sub-pixel, 110c: sub-pixel, 111A: conductive film, 111a: pixel electrode, 111b: pixel electrode, 111c: pixel electrode, 112: first layer, 112G: organic layer, 113: light-emitting layer, 113a: first light-emitting layer, 113b: second light-emitting layer, 113c: third light-emitting layer, 113aG: organic layer, 113bG: organic layer, 113cG: organic layer, 114: second layer, 114G: organic layer, 115: third layer, 116: common electrode, 117: light-shielding layer, 118: insulating layer, 120: substrate, 122: resin layer, 123: conductive layer, 124a: pixel, 124b: pixel, 125 : insulating layer, 125A: insulating film, 126: optical adjustment layer, 126a: conductive layer, 126b: conductive layer, 126c: conductive layer, 127: insulating layer, 127A: insulating film, 128: layer, 130: light-emitting device, 130a: light-emitting device, 130b: light-emitting device, 130c: light-emitting device, 131: protective layer, 132: protective layer, 138: region, 140: connecting portion, 142: adhesive layer, 151: substrate, 152: substrate, 153: insulating layer, 162: display portion, 164: circuit, 165: wiring, 166: conductive layer, 172: FPC, 173: IC, 190a: resist mask, 190b: 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, 222c: conductive layer, 223: conductive layer, 225: insulating layer, 228: region, 231: semiconductor layer, 231i: channel formation region, 231n: low resistance region, 240: capacitance, 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, 256: plug, 261: insulating layer, 262: insulating layer, 263: insulating layer, 264: insulating layer, 265: insulating layer, 271: plug, 274: plug, 274a: conductive layer, 274b: conductive layer, 280: display module, 281: display section, 282: circuit section, 283: pixel circuit section, 283a: pixel circuit, 284: pixel section, 284a: pixel, 285: terminal section, 286: wiring section, 290: FPC, 291: substrate, 292: substrate, 301: substrate, 301A: substrate, 301B: substrate, 310: transistor, 310A: transistor, 3 10B: transistor, 311: conductive layer, 312: low resistance region, 313: insulating layer, 314: insulating layer, 315: element isolation layer, 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, 401: substrate, 410: transistor, 410a: Transistor, 411: semiconductor layer, 411i: channel formation region, 411n: low resistance region, 412: insulating layer, 413: conductive layer, 414a: conductive layer, 414b: conductive layer, 415: conductive layer, 416: insulating layer, 421: insulating layer, 422: insulating layer, 423: insulating layer, 426: insulating layer, 431: conductive layer, 450: transistor, 450a: transistor, 451: semiconductor layer, 452: insulating layer, 453: conductive layer, 454a: conductive layer, 454b: conductive layer, 455: conductive layer, 700A: electronic device, 700B: electronic device, 721: housing, 723: wearing part, 727: earphone unit, 750: earphone, 751: display panel, 753: optical member, 756: display area, 757: frame, 758: nose pad, 772: lower electrode, 785: layer, 786: EL layer, 786a: EL layer, 786b: EL layer, 788: upper electrode, 800A: electronic device, 800B: electronic device, 820: display unit, 821: housing, 822: communication unit, 823: wearing unit, 824: control unit, 825: imaging unit, 827: earphone unit, 832: lens, 4411: light-emitting layer, 4412: light-emitting layer, 4413: light-emitting layer, 4420: layer, 4421: layer, 4422: layer, 4430: layer,4431: layer, 4432: layer, 4440: charge generation layer, 6500: electronic device, 6501: housing, 6502: display unit, 6503: power button, 6504: button, 6505: speaker, 6506: microphone, 6507: camera, 6508: light source, 6510: protective member, 6511: display panel, 6512: optical member, 6513: touch sensor panel, 6515: FPC, 6516: IC, 6517: printed circuit board, 6518: battery, 7000: display unit, 7100: television device, 7101: housing, 7103: stand, 7111: remote control device, 7200: notebook 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 unit, 9002: camera, 9003: speaker, 9005: operation keys, 9006: connection terminal, 9007: sensor, 9008: microphone, 9050: icon, 9051: information, 9052: information, 9053: information, 9054: information, 9055: hinge, 9101: mobile information terminal, 9102: mobile information terminal, 9103: tablet terminal, 9200: mobile information terminal, 9201: mobile information terminal,

Claims

1. It has a first insulating layer, a first light-emitting element on the first insulating layer, and a second light-emitting element on the first insulating layer. The first light-emitting element and the second light-emitting element have functions of emitting light of different colors from each other. The first light-emitting element has a first pixel electrode, a first EL layer having a region located on the first pixel electrode, and a common electrode having a region located on the first EL layer. The second light-emitting element has a second pixel electrode, a second EL layer having a region located on the second pixel electrode, and the common electrode having a region located on the second EL layer. The first EL layer has a first layer having a region located on the first pixel electrode and a first light-emitting layer having a region located on the first layer. The first layer has a hole injection layer. In a cross-sectional view, the first insulating layer has a recess located in a region between the first pixel electrode and the second pixel electrode. The first insulating layer has a region where an angle formed by a bottom surface extension line extending parallel to the bottom surface of the first pixel electrode from the lowermost part of the recess downward to below the first pixel electrode and a side surface of the recess is 60 degrees or more and 140 degrees or less. A display device.

2. In Claim 1, A display device in which a ratio (ET / T2) of a shortest distance ET from the bottom surface extension line to the upper surface of the first pixel electrode to a film thickness T2 of the first layer is 0.5 or more.

3. In Claim 1, A display device having a second insulating layer having a region in contact with a side surface of the first pixel electrode and a region in contact with a side surface of the second pixel electrode.

4. In Claim 3, It has a third insulating layer in a region between the first pixel electrode and the second pixel electrode and located below the common electrode. The second EL layer has a second layer having a region located on the second pixel electrode and a second light-emitting layer having a region located on the second layer. In a region between the first light-emitting element and the second light-emitting element, the second insulating layer has a region disposed below the common electrode via the third insulating layer. In a region between the first light-emitting element and the second light-emitting element, it has a first organic layer having a region located below the second insulating layer. A display device, wherein the first organic layer, the first layer, and the second layer contain the same material.

5. In Claim 4, a second organic layer having a region located on the first organic layer, and a third organic layer having a region located on the first organic layer. The second organic layer contains the same material as the first light-emitting layer. A display device, wherein the third organic layer contains the same material as the second light-emitting layer.