Method for manufacturing display device

Abstract

To provide a display device with high definition or high resolution.SOLUTION: A first light-emitting device, a second light-emitting device, a first insulating layer, a first color conversion layer, and a second color conversion layer, the first light-emitting device includes a first pixel electrode, a first light-emitting layer over the first pixel electrode, and a common electrode over the first light-emitting layer, the second light-emitting device includes a second pixel electrode, a second light-emitting layer over the second pixel electrode, and a common electrode over the second light-emitting layer; The first insulating layer covers side surfaces of the first pixel electrode, the second pixel electrode, the first light-emitting layer, and the second light-emitting layer, the first color conversion layer is provided to overlap with the first light-emitting device, the second color conversion layer is provided to overlap with the second light-emitting device, the first light-emitting device and the second light-emitting device have a function of emitting blue light, and the first color conversion layer and the second color conversion layer have a function of converting blue light into light with a different wavelength.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[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. [Background technology]

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

[0004] Representative examples of display devices that can be applied to display panels include liquid crystal display devices, organic EL (Electro Luminescence) elements, light-emitting devices equipped with light-emitting elements (also called light-emitting devices) such as light-emitting diodes (LEDs), and electronic paper that displays using electrophoresis methods.

[0005] For example, the basic structure of an organic EL element (also called an organic EL device) 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] The use of quantum dots as a color conversion (wavelength conversion) material in organic EL devices is also being considered. Quantum dots are semiconductor nanocrystals with a diameter of several nanometers, and their size is estimated at 1×10 3 Pieces to 1×10 6 Quantum dots are composed of approximately 100 atoms. Electrons, holes, and excitons are confined inside quantum dots, resulting in discrete energy states, and the energy shifts depending on the size. In other words, even quantum dots made of the same material will emit different wavelengths depending on their size, so the emission wavelength can be easily adjusted by changing the size of the quantum dots used. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-324673 Summary of the Invention [Problem to be solved by the invention]

[0008] 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.

[0009] 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.

[0010] 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. [Means for solving the problem]

[0011] One aspect of the present invention is a display device including a first pixel and a second pixel arranged adjacent to the first pixel, the first pixel including a 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, and a first color conversion layer over the first light-emitting element, and the second pixel including a 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 a second color conversion layer over the second light-emitting element, The first light-emitting element and the second light-emitting element have a function of emitting blue light, the first color conversion layer has a function of converting light emitted by the first light-emitting element into light of a different wavelength, the second color conversion layer has a function of converting light emitted by the second light-emitting element into light of a different wavelength, the first pixel and the second pixel have mutually different colors, and the side surfaces of the first pixel electrode, the first EL layer, the second pixel electrode, and the second EL layer have regions in contact with the first insulating layer.

[0012] One embodiment of the present invention is a display device including a first pixel and a second pixel arranged adjacent to the first pixel, the first pixel including a 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, and a first color conversion layer over the first light-emitting element, and the second pixel including a 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 a second color conversion layer over the second light-emitting element, wherein the first light-emitting element and the second light-emitting element have a function of emitting blue light, and the first color conversion layer The color conversion layer has a function of converting light emitted by the first light-emitting element into light of a different wavelength, and the second color conversion layer has a function of converting light emitted by the second light-emitting element into light of a different wavelength. The first pixel and the second pixel exhibit colors different from each other. The side surfaces of the first pixel electrode, the side surfaces of the first EL layer, the side surfaces of the second pixel electrode, and the side surfaces of the second EL layer have regions in contact with the first insulating layer. The display device has a second insulating layer that is provided on and in contact with the first insulating layer and is arranged below the common electrode, and the first insulating layer has an inorganic material, and the second insulating layer has an organic material.

[0013] One embodiment of the present invention is a display device including a first pixel and a second pixel arranged adjacent to the first pixel, the first pixel including a first light-emitting element having a first pixel electrode, a first EL layer on the first pixel electrode, a common layer on the first EL layer, and a common electrode on the common layer, and a first color conversion layer on the first light-emitting element, and the second pixel including a second light-emitting element having a second pixel electrode, a second EL layer on the second pixel electrode, a common layer on the second EL layer, and a common electrode on the common layer, and a second color conversion layer on the second light-emitting element. The element has a function of emitting blue light, the first color conversion layer has a function of converting light emitted by the first light-emitting element into light of a different wavelength, the second color conversion layer has a function of converting light emitted by the second light-emitting element into light of a different wavelength, the first pixel and the second pixel exhibit colors different from each other, the side surfaces of the first pixel electrode, the side surfaces of the first EL layer, the side surfaces of the second pixel electrode, and the side surfaces of the second EL layer have regions in contact with the first insulating layer, and the top surface of the first EL layer, the top surface of the second EL layer, and the top surface of the first insulating layer have regions in contact with a common layer.

[0014] One embodiment of the present invention is a display device including a first pixel and a second pixel arranged adjacent to the first pixel, wherein the first pixel includes a first light-emitting element having a first pixel electrode, a first EL layer over the first pixel electrode, a common layer over the first EL layer, and a common electrode over the common layer, and a first color conversion layer over the first light-emitting element; and the second pixel includes a second light-emitting element having a second pixel electrode, a second EL layer over the second pixel electrode, a common layer over the second EL layer, and a common electrode over the common layer, and a second color conversion layer over the second light-emitting element, wherein the first light-emitting element and the second light-emitting element have a function of emitting blue light, and the first color conversion layer converts light emitted by the first light-emitting element into a different color. the first pixel and the second pixel exhibit colors different from each other; a side surface of the first pixel electrode, a side surface of the first EL layer, a side surface of the second pixel electrode, and a side surface of the second EL layer have regions in contact with a first insulating layer; a second insulating layer is provided on and in contact with the first insulating layer and disposed below a common electrode; the first insulating layer contains an inorganic material; the second insulating layer contains an organic material; and an upper surface of the first EL layer, an upper surface of the second EL layer, an upper surface of the first insulating layer, and an upper surface of the second insulating layer have regions in contact with the common layer.

[0015] In the display device according to one embodiment of the present invention, the common layer preferably includes at least one of a hole injection layer, a hole blocking layer, a hole transport layer, an electron transport layer, an electron blocking layer, and an electron injection layer.

[0016] In a display device of one embodiment of the present invention, it is preferable that the first EL layer includes a first light-emitting layer, a first charge generation layer over the first light-emitting layer, and a second light-emitting layer over the first charge generation layer, and the second EL layer includes a third light-emitting layer, a second charge generation layer over the third light-emitting layer, and a fourth light-emitting layer over the second charge generation layer, the first light-emitting layer and the third light-emitting layer contain the same material, the second light-emitting layer and the fourth light-emitting layer contain the same material, and the first charge generation layer and the second charge generation layer contain the same material, and the first insulating layer has at least a region in contact with a side surface of the first charge generation layer and a region in contact with a side surface of the second charge generation layer.

[0017] In the above-described display device according to one embodiment of the present invention, each of the first color conversion layer and the second color conversion layer preferably contains quantum dots or a phosphor.

[0018] One aspect of the present invention is a display module having a display device having any of the above configurations, and including a connector such as a flexible printed circuit (hereinafter referred to as FPC) or a TCP (Tape Carrier Package), or a display module having an integrated circuit (IC) mounted thereon by a COG (Chip On Glass) method or a COF (Chip On Film) method.

[0019] One embodiment of the present invention is an electronic device including the above-described display module and at least one of a housing, a battery, a camera, a speaker, and a microphone. [Effects of the Invention]

[0020] 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.

[0021] 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.

[0022] 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. [Brief explanation of the drawings]

[0023] [Figure 1] 1A and 1B are a top view and a cross-sectional view, respectively, illustrating an example of a display device. [Figure 2] 2A and 2B are cross-sectional views showing an example of a display device. [Figure 3] 3A to 3C are cross-sectional views showing an example of a display device. [Figure 4] 4A and 4B are a top view and a cross-sectional view illustrating an example of a display device. [Figure 5] 5A to 5F are top views showing an example of a pixel. [Figure 6] 6A to 6C are schematic diagrams showing an example of an electronic device. [Figure 7] 7A and 7B are top views illustrating an example of a method for manufacturing a display device. [Figure 8] 8A to 8C are cross-sectional views showing an example of a method for manufacturing a display device. [Figure 9] 9A to 9C are cross-sectional views showing an example of a method for manufacturing a display device. [Figure 10] 10A to 10C are cross-sectional views showing an example of a method for manufacturing a display device. [Figure 11] 11A to 11C are cross-sectional views showing an example of a method for manufacturing a display device. [Figure 12] 12A to 12C are cross-sectional views showing an example of a method for manufacturing a display device. [Figure 13] 13A to 13C are cross-sectional views showing an example of a method for manufacturing a display device. [Figure 14] 14A to 14F are cross-sectional views showing an example of a method for manufacturing a display device. [Figure 15] 15A and 15B are cross-sectional views showing an example of a display device. [Figure 16] 16A and 16B are cross-sectional views showing an example of a display device. [Figure 17] FIG. 17 is a perspective view showing an example of a display device. [Figure 18] 18A is a cross-sectional view showing an example of a display device, and FIGS. 18B and 18C are cross-sectional views showing an example of a transistor. [Figure 19] FIG. 19 is a cross-sectional view showing an example of a display device. [Figure 20] 20A to 20D are cross-sectional views showing an example of a display device. [Figure 21] 21A and 21B are perspective views showing an example of a display module. [Figure 22] FIG. 22 is a cross-sectional view showing an example of a display device. [Figure 23] FIG. 23 is a cross-sectional view showing an example of a display device. [Figure 24] FIG. 24 is a cross-sectional view showing an example of a display device. [Figure 25] FIG. 25 is a cross-sectional view showing an example of a display device. [Figure 26] FIG. 26 is a cross-sectional view showing an example of a display device. [Figure 27] Fig. 27A is a block diagram showing an example of a display device, and Fig. 27B to Fig. 27D are diagrams showing an example of a pixel circuit. [Figure 28] 28A to 28D are cross-sectional views showing an example of a transistor. [Figure 29] 29A and 29B are diagrams showing an example of an electronic device. [Figure 30] 30A and 30B are diagrams showing an example of an electronic device. [Figure 31] 31A and 31B are diagrams showing an example of an electronic device. [Figure 32] 32A to 32D are diagrams showing an example of an electronic device. [Figure 33]33A to 33G are diagrams showing an example of an electronic device. [Figure 34] 34A to 34C are cross-sectional views showing an example of a display device. [Figure 35] 35A to 35C are cross-sectional views showing an example of a display device. DETAILED DESCRIPTION OF THE INVENTION

[0024] 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.

[0025] 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. Furthermore, when referring to similar functions, the same hatching pattern may be used and no particular reference numeral may be assigned.

[0026] 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.

[0027] 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."

[0028] (Embodiment 1) In this embodiment, a display device of one embodiment of the present invention and a manufacturing method thereof will be described with reference to FIGS.

[0029] 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 pixel includes a light-emitting device (also referred to as a light-emitting element) that emits blue light and a color conversion layer overlapping with the light-emitting device.

[0030] In this specification, a pixel refers to, for example, one element whose brightness can be controlled. As an example, a pixel refers to one color element, and the brightness is expressed by that color element. In the case of a color display device using 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 RGB pixel can also be called a subpixel, and the three RGB subpixels can be collectively called a pixel. A full-color display can be achieved by using a color conversion layer in each subpixel, which has the function of converting light into light of different wavelengths. Furthermore, the light-emitting devices used in each pixel can be formed using the same material, simplifying the manufacturing process and reducing manufacturing costs.

[0031] As the light-emitting device, it is preferable to use an EL device (also called an EL element) such as an OLED (organic LED) or a QLED (quantum-dot LED). Examples of light-emitting materials that EL devices have include fluorescent materials, phosphorescent materials, inorganic compounds (such as quantum dot materials), and materials that exhibit thermally activated delayed fluorescence (thermally activated delayed fluorescence (TADF) materials). LEDs such as micro LEDs can also be used as the light-emitting device.

[0032] When the light-emitting device of each pixel is formed using a blue-emitting organic EL device, there is no need to separately paint the light-emitting layer for each pixel. Therefore, layers other than the pixel electrode (e.g., the light-emitting layer) included in the light-emitting device can be common to each pixel. However, some layers included in the light-emitting device have relatively high conductivity, and providing a common layer with high conductivity for 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, this leakage current can become significant and may cause 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 a portion of the light-emitting device in each pixel is formed in an island shape, thereby achieving high resolution and high reliability of the display device. Here, the island-shaped portion of the light-emitting device includes the light-emitting layer.

[0033] 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.

[0034] For example, island-shaped light-emitting layers can be formed by vacuum deposition using a metal mask (also known as a shadow mask). However, this method can result in deviations in the shape and position of the island-shaped light-emitting layers from the design due to various factors, such as the accuracy of the metal mask, misalignment between the metal mask and the substrate, deflection of the metal mask, and the spread of the contours of the formed film due to vapor scattering, making it difficult to achieve high-definition and high-aperture displays. Furthermore, during deposition, the contours of the layer can become blurred, resulting in thin edges. In other words, the thickness of the island-shaped light-emitting layer can vary depending on the location. Furthermore, when fabricating large, high-resolution, or high-definition display devices, there is a concern that low manufacturing yields may be caused by low dimensional accuracy of the metal mask and deformation due to heat, etc.

[0035] In a manufacturing method of a display device according to one embodiment of the present invention, a layer including a conductive film and a light-emitting layer (which can be referred to as an EL layer or a part of the EL layer) is formed over the entire surface, and then a sacrificial layer (also referred to as a mask layer) is formed over the EL layer. A resist mask is then formed over the sacrificial layer, and the EL layer and the sacrificial layer are processed using the resist mask to form an island-shaped EL layer and an island-shaped pixel electrode (which can also be referred to as a lower electrode). Here, the EL layer includes at least a light-emitting layer and can also be referred to as a light-emitting unit.

[0036] As described above, in the manufacturing method of a display device according to one embodiment of the present invention, the island-shaped EL layer is formed by forming the EL layer on the entire surface and then processing it, rather than by using a metal mask pattern. Therefore, it is possible to realize a high-definition display device or a display device with a high aperture ratio, which has been difficult to achieve until now. Furthermore, by providing a sacrificial layer on the EL layer, damage to the EL layer during the manufacturing process of the display device can be reduced, thereby improving the reliability of the light-emitting device.

[0037] Furthermore, as described above, after forming the island-shaped EL layers, the sacrificial layer remaining on each EL layer can be used as a hard mask to process the conductive film to form pixel electrodes. Since there is no need to provide a separate mask for forming the island-shaped pixel electrodes, the manufacturing cost of the display device can be reduced. Furthermore, there is no need to provide an insulating layer between the pixel electrodes and the EL layer to cover the edges of the pixel electrodes, so the distance between adjacent light-emitting devices can be made extremely narrow. This allows for higher definition or higher resolution of the display device. Furthermore, there is no need for a mask for forming the insulating layer, so the manufacturing cost of the display device can be reduced.

[0038] While it is difficult to achieve a spacing of less than 10 μm between adjacent light-emitting devices using, for example, a metal mask, the above-described method can narrow the spacing to 8 μm or less, 6 μm or less, 4 μm or less, 3 μm or less, 2 μm or less, or even 1 μm or less. Furthermore, by using, for example, an exposure device for LSIs, the spacing can be narrowed to 500 nm or less, 200 nm or less, 100 nm or less, or even 50 nm or less. This significantly reduces the area of ​​the non-light-emitting region that may exist between two light-emitting devices, enabling the aperture ratio to approach 100%. For example, the aperture ratio can be 50% or more, 60% or more, 70% or more, 80% or more, or even 90% or more, but can be less than 100%.

[0039] Furthermore, the pattern of the EL layer itself can be made much smaller than when a metal mask is used. Furthermore, for example, when a metal mask is used to separately create an EL layer, thickness variations occur between the center and edges of the pattern, resulting in a smaller effective area that can be used as the light-emitting region compared to the overall area of ​​the pattern. On the other hand, with the above-mentioned manufacturing method, a pattern is formed by processing a film deposited to a uniform thickness, so the thickness can be made uniform within the pattern, and even with a fine pattern, almost the entire area can be used as the light-emitting region. This makes it possible to manufacture a display device that combines high definition and a high aperture ratio.

[0040] In a light-emitting device that emits blue light, 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 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, the sacrificial layer is removed, and the remaining layers constituting the EL layer (for example, a carrier injection layer) and a common electrode (which can also be called an upper electrode) can be formed in common.

[0041] On the other hand, the carrier injection layer is often a relatively highly conductive layer in a light-emitting device. Therefore, contact of the carrier injection layer with 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 of the common electrode with 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.

[0042] Therefore, a display device according to one embodiment of the present invention includes an insulating layer that covers 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.

[0043] A display device of one embodiment of the present invention includes a pixel electrode that functions as an anode; a hole-injection layer, a hole-transport layer, a light-emitting layer, and an electron-transport layer that are each provided in this order over the pixel electrode, and each have an island shape; insulating layers that are 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 that is provided over the electron-transport layer; and a common electrode that is provided over the electron-injection layer and functions as a cathode.

[0044] Alternatively, a display device of one embodiment of the present invention includes a pixel electrode that functions as a cathode; an electron-injection layer, an electron-transport layer, a light-emitting layer, and a hole-transport layer that are provided in this order over the pixel electrode, each of which has an island shape; insulating layers that are 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 that is provided over the hole-transport layer; and a common electrode that is provided over the hole-injection layer and functions as an anode.

[0045] Alternatively, a display device according to one embodiment of the present invention includes a pixel electrode, a first light-emitting unit on the pixel electrode, an intermediate layer (also referred to as a charge generation layer) on the first light-emitting unit, a second light-emitting unit on 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 on 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.

[0046] 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, which can prevent them from contacting a common electrode or the like. Therefore, short circuits in the light-emitting device can be prevented, and the reliability of the light-emitting device can be improved.

[0047] In addition, in the display device of one embodiment of the present invention, all of the light-emitting devices included in each pixel emit blue light, and the light is converted into light of a different wavelength by a color conversion layer, thereby achieving full color. Therefore, compared to the case of manufacturing a light-emitting device that emits white light, the number of EL layers to be formed and the types of materials can be reduced, and therefore the manufacturing apparatus and process can be simplified, leading to an improved yield.

[0048] This configuration allows the fabrication of a highly reliable display device with high definition or resolution. For example, even with an arrangement method using three or more sub-pixels per pixel, an extremely high-definition display device can be realized without the need to artificially increase the definition by applying a special pixel arrangement method such as a pen-tile method. For example, a display device with a so-called stripe arrangement in which R, G, and B are each arranged in one direction can be realized, and with a resolution of 500 ppi or more, 1000 ppi or more, 2000 ppi or more, or even 3000 ppi or more, or even 5000 ppi or more.

[0049] It is preferable to use phosphors or quantum dots (QDs) for the color conversion layer. Quantum dots have a narrow peak width in the emission spectrum, and can emit light with good color purity. This can improve the display quality of the display device.

[0050] The insulating layer may have a single-layer structure or a laminated structure. It is particularly preferable to use an insulating layer with a two-layer structure. For example, since the first insulating layer is formed in contact with the EL layer, it is preferably formed using an inorganic insulating material. It is particularly preferable to form it using atomic layer deposition (ALD), which causes less film damage. It is also preferable to form the inorganic insulating layer using sputtering, chemical vapor deposition (CVD), or plasma enhanced CVD (PECVD), which have faster film formation rates than ALD. This allows for the production of highly reliable display devices with high productivity. It is also preferable to form the second insulating layer using an organic material so as to flatten recesses formed in the first insulating layer.

[0051] For example, an aluminum oxide film formed by ALD can be used as the first insulating layer, and a photosensitive organic resin film can be used as the second insulating layer.

[0052] Alternatively, an insulating layer having a single layer structure may be formed. For example, by forming an insulating layer having a single layer structure using an inorganic material, the insulating layer can be used as a protective insulating layer for the EL layer. This can improve the reliability of the display device. Furthermore, by forming an insulating layer having a single layer structure using an organic material, the insulating layer can fill the gap between adjacent EL layers and achieve planarization. This can improve the coverage of the common electrode (upper electrode) formed on the EL layer and the insulating layer.

[0053] [Display device configuration example 1] 1A and 1B show a display device according to one embodiment of the present invention.

[0054] 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.

[0055] A stripe arrangement is applied to pixel 110 shown in Fig. 1A. Pixel 110 shown in Fig. 1A is composed of three subpixels, 110a, 110b, and 110c. Subpixels 110a, 110b, and 110c each have blue-emitting light-emitting devices 130a, 130b, and 130c (hereinafter, these may be collectively referred to as light-emitting devices 130).

[0056] In FIG. 1, subpixel 110a and subpixel 110b are provided with color conversion layers 129a and 129b (hereinafter, sometimes collectively referred to as color conversion layer 129) superimposed on light-emitting devices 130a and 130b, respectively, while subpixel 110c does not have a color conversion layer. For example, color conversion layer 129a can convert blue light into red light, and color conversion layer 129b can convert blue light into green light. As a result, red light is extracted to the outside from subpixel 110a, and green light is extracted to the outside from subpixel 110b. Blue light emitted by light-emitting device 130c is extracted from subpixel 110c, which does not have a color conversion layer. 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). For example, a color conversion layer may be provided in the sub-pixel 110c to form a sub-pixel of three colors of yellow (Y), cyan (C), and magenta (M).

[0057] 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.

[0058] 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 of the upper, right, left, and lower sides 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.

[0059] FIG. 1B shows a cross-sectional view taken along the dashed line X1-X2 in FIG. 1A.

[0060] 1B, display device 100 includes light-emitting devices 130a, 130b, and 130c provided on layer 101 including transistors (not shown), and protective layers 131 and 132 provided to cover these light-emitting devices. Color conversion layers 129a and 129b are provided on protective layer 132. Substrate 120 is further bonded thereon with resin layer 122. In addition, insulating layer 125 and insulating layer 127 on insulating layer 125 are provided in the regions between adjacent light-emitting devices.

[0061] 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.

[0062] The layer 101 may have a laminated structure in which, for example, a plurality of transistors (not shown) are provided on a substrate and an insulating layer is provided to cover these transistors. The layer 101 may have a recess between adjacent light-emitting devices. For example, the recess may be provided in the insulating layer located on the outermost surface of the layer 101. Examples of the structure of the layer 101 will be described later in the third and fourth embodiments.

[0063] Preferably, the light-emitting devices 130a, 130b, and 130c each emit blue (B) light. By providing color conversion layers 129a and 129b, which have the function of converting light into different colors, on the light-emitting devices 130a and 130b, respectively, and not providing a color conversion layer on the light-emitting device 130c, it is possible to form sub-pixels 110a, 110b, and 110c that emit light of different colors.

[0064] Note that the light-emitting devices 130a, 130b, and 130c that can be used in the display device of one embodiment of the present invention are not limited to light-emitting devices that emit blue light. For example, light-emitting devices that emit ultraviolet light can also be used. When light-emitting devices that emit ultraviolet light are used as the light-emitting devices 130a, 130b, and 130c, color conversion layers 129 that convert light of different colors may be provided over the light-emitting devices 130a, 130b, and 130c. For example, a color conversion layer that converts ultraviolet light to light with a red wavelength can be provided as the color conversion layer 129a, a color conversion layer that converts ultraviolet light to light with a green wavelength can be provided as the color conversion layer 129b, and a color conversion layer that converts ultraviolet light to light with a blue wavelength can be provided over the light-emitting device 130c. In this way, red light can be extracted from the subpixel 110a, green light can be extracted from the subpixel 110b, and blue light can be extracted from the subpixel 110c, thereby achieving a full-color display device.

[0065] The light-emitting devices 130a, 130b, and 130c are preferably EL devices such as OLEDs or QLEDs. Examples of light-emitting materials used in EL devices include fluorescent materials, phosphorescent materials, inorganic compounds (such as quantum dot materials), and thermally activated delayed fluorescence (TADF) materials. The TADF material may be a material that is in thermal equilibrium between a singlet excited state and a triplet excited state. Such TADF materials have a short emission lifetime (excitation lifetime), which can suppress a decrease in efficiency in the high-brightness region of the light-emitting device.

[0066] A light-emitting device has an EL layer between a pair of electrodes. In this specification and the like, one of the pair of electrodes may be referred to as a pixel electrode and the other as a common electrode.

[0067] 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.

[0068] The light-emitting device 130a has a pixel electrode 111a on the layer 101, an island-shaped first layer 113a on the pixel electrode 111a, a fifth layer 114 on the island-shaped first layer 113a, and a common electrode 115 on the fifth layer 114. In the light-emitting device 130a, the first layer 113a and the fifth layer 114 can be collectively referred to as an EL layer.

[0069] The structure of the light emitting device of this embodiment is not particularly limited, and may be a single structure or a tandem structure. An example of the structure of the light emitting device will be described later in the second embodiment.

[0070] Light-emitting device 130b has a pixel electrode 111b on layer 101, an island-shaped second layer 113b on pixel electrode 111b, a fifth layer 114 on the island-shaped second layer 113b, and a common electrode 115 on the fifth layer 114. In light-emitting device 130b, second layer 113b and fifth layer 114 can be collectively referred to as an EL layer.

[0071] The light-emitting device 130c includes a pixel electrode 111c on the layer 101, an island-shaped third layer 113c on the pixel electrode 111c, a fifth layer 114 on the island-shaped third layer 113c, and a common electrode 115 on the fifth layer 114. In the light-emitting device 130c, the third layer 113c and the fifth layer 114 can be collectively referred to as an EL layer.

[0072] The light-emitting devices of each color share the same film as a common electrode. The common electrode shared by all the light-emitting devices is electrically connected to a conductive layer provided in the connection section 140. This allows the same potential to be supplied to the common electrode of each light-emitting device.

[0073] 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.

[0074] The pair of electrodes (pixel electrode and common electrode) of the light-emitting device can be formed from a metal, an alloy, an electrically conductive compound, a mixture thereof, etc. 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 aluminum alloy (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 usable materials 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 these metals in combination. Other examples include rare earth metals such as elements belonging to Groups 1 and 2 of the periodic table (e.g., lithium (Li), cesium (Cs), calcium (Ca), and strontium (Sr)), europium (Eu), and ytterbium (Yb), as well as alloys containing these metals in combination, graphene, and the like.

[0075] A 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 a microcavity structure in the light-emitting device, 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.

[0076] The semi-transmitting and semi-reflective electrode may have a laminated structure of a reflective electrode and an electrode that is transparent to visible light (also called a transparent electrode).

[0077] 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. In addition, the resistivity of these electrodes is 1×10 -2 Ωcm or less is preferable.

[0078] The first layer 113a, the second layer 113b, and the third layer 113c are each provided in an island shape. The first layer 113a, the second layer 113b, and the third layer 113c each have a light-emitting layer. The first layer 113a, the second layer 113b, and the third layer 113c preferably have a light-emitting layer that emits blue light. Here, the island-shaped first layer 113a, the island-shaped second layer 113b, and the island-shaped third layer 113c preferably contain the same material. In other words, the island-shaped first layer 113a, the island-shaped second layer 113b, and the island-shaped third layer 113c are preferably formed by patterning films formed in the same process.

[0079] 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 light-emitting materials include fluorescent materials, phosphorescent materials, TADF materials, and quantum dot materials.

[0080] 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.

[0081] 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.

[0082] 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). One or more organic compounds may be a hole-transporting material or an electron-transporting material, or both. Alternatively, a bipolar material or a TADF material may be used as the one or more organic compounds.

[0083] The light-emitting layer preferably contains, 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-Triplet 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, the 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.

[0084] The first layer 113a, the second layer 113b, and the third layer 113c 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.

[0085] 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), transfer, printing, inkjet printing, or coating.

[0086] For example, the first layer 113a, the second layer 113b, and the third layer 113c may each include one or more of a hole injection layer, a hole transport layer, a hole blocking layer, an electron blocking layer, an electron transport layer, and an electron injection layer.

[0087] The EL layer may be formed in common to all light-emitting devices, and may include one or more of a hole injection layer, a hole transport layer, a hole blocking layer (sometimes called a hole inhibiting layer), an electron blocking layer (sometimes called an electron inhibiting layer), an electron transport layer, and an electron injection layer. For example, the fifth layer 114 may be a carrier injection layer (hole injection layer or electron injection layer).

[0088] Each of the first layer 113a, the second layer 113b, and the third layer 113c preferably includes a light-emitting layer and a carrier transport layer on the light-emitting layer. This prevents the light-emitting layer from being exposed to the outermost surface during the manufacturing process of the display device 100, thereby reducing damage to the light-emitting layer. This improves the reliability of the light-emitting device.

[0089] 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).

[0090] 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 transport material. The hole transport material is a material having a concentration of 1×10 -6 cm 2 A material having a hole mobility of 1 / Vs or more is preferred. Note that other materials 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.

[0091] 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 2A 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 π-electron-deficient heteroaromatic compounds including nitrogen-containing heteroaromatic compounds.

[0092] 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.

[0093] 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).

[0094] 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 xThe electron injection layer may be formed of an alkali metal, an alkaline earth metal, such as cesium carbonate, or a compound thereof. 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.

[0095] 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.

[0096] The organic compound having an unshared electron pair preferably has a lowest unoccupied molecular orbital (LUMO) 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.

[0097] Examples of organic compounds with lone electron pairs include 4,7-diphenyl-1,10-phenanthroline (abbreviated as BPhen), 2,9-bis(naphthalen-2-yl)-4,7-diphenyl-1,10-phenanthroline (abbreviated as NBPhen), diquinoxalino[2,3-a:2',3'-c]phenazine (abbreviated as HATNA), and 2,4,6-tris[3'-(pyridin-3-yl)biphenyl-3-yl]-1,3,5-triazine (abbreviated as TmPPPyTz). NBPhen has a higher glass transition temperature (Tg) and better heat resistance than BPhen.

[0098] When fabricating a tandem-structure light-emitting device, an intermediate layer is provided between the 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.

[0099] 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.

[0100] The side surfaces of the pixel electrodes 111a, 111b, and 111c, the first layer 113a, the second layer 113b, and the third layer 113c are covered with the insulating layer 125 and the insulating layer 127. This prevents the fifth layer 114 (or the common electrode 115) from coming into contact with any of the side surfaces of the pixel electrodes 111a, 111b, and 111c, the first layer 113a, the second layer 113b, and the third layer 113c, thereby preventing short circuits in the light-emitting device.

[0101] Furthermore, when the first layer 113a, the second layer 113b, and the third layer 113c have 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 fifth layer 114 (or the common electrode 115) from coming into contact with any of the side surfaces of the plurality of light-emitting units and the intermediate layer, thereby preventing a short circuit in the light-emitting device.

[0102] The insulating layer 125 preferably covers at least the side surfaces of the pixel electrodes 111a, 111b, and 111c. Furthermore, the insulating layer 125 preferably covers the side surfaces of the first layer 113a, the second layer 113b, and the third layer 113c. The insulating layer 125 can be configured to be in contact with the side surfaces of the pixel electrodes 111a, 111b, and 111c, the first layer 113a, the second layer 113b, and the third layer 113c. The insulating layer 125 is preferably an insulating layer containing an inorganic material.

[0103] The insulating layer 127 is provided on the insulating layer 125 so as to fill recesses formed in the insulating layer 125. The insulating layer 127 can be configured to overlap with the side surfaces of the pixel electrodes 111a, 111b, 111c, the first layer 113a, the second layer 113b, and the third layer 113c via the insulating layer 125. The insulating layer 127 is preferably an insulating layer containing an organic material.

[0104] 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 in contact with each side surface of the first layer 113a, the second layer 113b, and the third layer 113c. The absence of the insulating layer 125 or the insulating layer 127 can reduce the number of manufacturing steps of the display device. On the other hand, the insulating layer 125 containing an inorganic material can be provided in contact with each side surface of the first layer 113a, the second layer 113b, and the third layer 113c to effectively prevent impurities from entering these layers. Furthermore, the provision of the insulating layer 127 can improve the flatness of the surfaces on which the fifth layer 114 and the common electrode 115 are formed.

[0105] The fifth layer 114 and the common electrode 115 are provided over the first layer 113a, the second layer 113b, the third layer 113c, 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 and the EL layer are provided and a region where the pixel electrode and the EL layer are not provided (a region between light-emitting devices). In the display device of one embodiment of the present invention, the insulating layer 125 and the insulating layer 127 can planarize the step, thereby improving the coverage of the fifth layer 114 and the common electrode 115 with respect to the formation surface. Therefore, poor connection due to a step disconnection between the fifth layer 114 and the common electrode 115 can be suppressed. Alternatively, the step can suppress an increase in electrical resistance due to a local thinning of the common electrode 115.

[0106] In this specification and the like, the term "step discontinuity" refers to a phenomenon in which a layer, film, or electrode is divided due to the shape of the surface on which it is formed (for example, a step or the like).

[0107] In order to improve the flatness of the surfaces on which the fifth layer 114 and the common electrode 115 are formed, it is preferable that the heights of the upper surfaces of the insulating layers 125 and 127 are the same or approximately the same as the height of the upper surface of at least one of the first layer 113a, the second layer 113b, and the third layer 113c. The upper surface of the insulating layer 127 preferably has a flat shape, and may have protrusions or recesses.

[0108] The insulating layer 125 has a region in contact with each side surface of the first layer 113a, the second layer 113b, and the third layer 113c, and functions as a protective insulating layer for the first layer 113a, the second layer 113b, and the third layer 113c. By providing the insulating layer 125, impurities (oxygen, moisture, and the like) can be prevented from entering the first layer 113a, the second layer 113b, and the third layer 113c from each side surface thereof, thereby providing a highly reliable display device.

[0109] If the width (thickness) of the insulating layer 125 in the region in contact with each side surface of the first layer 113a, the second layer 113b, and the third layer 113c is large in a cross-sectional view, the distance between each of the first layer 113a, the second layer 113b, and the third layer 113c may become large, resulting in a low aperture ratio. Also, if the width (thickness) of the insulating layer 125 is small, the effect of suppressing impurities from entering the inside from each side surface of the first layer 113a, the second layer 113b, and the third layer 113c may become small. The width (thickness) of the insulating layer 125 in the region in contact with each side surface of the first layer 113a, the second layer 113b, and the third layer 113c 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 range, a display device having a high aperture ratio and high reliability can be obtained.

[0110] 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, an aluminum oxide film is preferable because it has a high etching selectivity with respect to the EL layer and functions to protect the EL layer in the formation of the insulating layer 127 described below. 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.

[0111] In this specification and elsewhere, an oxynitride refers to a material whose composition contains more oxygen than nitrogen, and a nitride oxide 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.

[0112] The insulating layer 125 can be formed by sputtering, CVD, pulsed laser deposition (PLD), ALD, etc. The insulating layer 125 is preferably formed by ALD, which has good coverage.

[0113] The insulating layer 127 provided on the insulating layer 125 has the function of flattening 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 115 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. A positive-type material or a negative-type material can be used as the photosensitive resin.

[0114] The difference in height between the top surface of the insulating layer 127 and the top surface of any of the first layer 113a, the second layer 113b, and the third layer 113c is, for example, preferably 0.5 times or less, more preferably 0.3 times or less, the thickness of the insulating layer 127. For example, the insulating layer 127 may be provided so that the top surface of any of the first layer 113a, the second layer 113b, and the third layer 113c is higher than the top surface of the insulating layer 127. For example, the insulating layer 127 may be provided so that the top surface of the insulating layer 127 is higher than the top surface of the light-emitting layer included in the first layer 113a, the second layer 113b, or the third layer 113c.

[0115] It is preferable to provide protective layers 131 and 132 on the light emitting devices 130a, 130b, and 130c. By providing the protective layers 131 and 132, the reliability of the light emitting devices can be improved.

[0116] There is no limitation on the conductivity of the protective layers 131 and 132. The protective layers 131 and 132 can be made of at least one of an insulating film, a semiconductor film, and a conductive film.

[0117] The protective layers 131 and 132 have inorganic films, which can prevent oxidation of the common electrode 115 and prevent 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.

[0118] The protective layers 131 and 132 can be made of inorganic insulating films such as an insulating oxide film, an insulating nitride film, an insulating oxynitride film, and an insulating nitride oxide film. Examples of insulating oxide 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 insulating nitride films include a silicon nitride film and an aluminum nitride film. Examples of insulating oxynitride films include a silicon oxynitride film and an aluminum oxynitride film. Examples of insulating nitride oxide films include a silicon nitride oxide film and an aluminum nitride oxide film.

[0119] Each of the protective layers 131 and 132 preferably includes an insulating nitride film or an insulating nitride oxide film, and more preferably includes an insulating nitride film.

[0120] Alternatively, an inorganic film containing In-Sn oxide (also referred to as ITO), In-Zn oxide, Ga-Zn oxide, Al-Zn oxide, or indium gallium zinc oxide (In-Ga-Zn oxide, also referred to as IGZO) may be used for the protective layers 131 and 132. The inorganic film preferably has high resistance, specifically, preferably has higher resistance than the common electrode 115. The inorganic film may further contain nitrogen.

[0121] When light emitted from the light-emitting device is extracted through the protective layers 131 and 132, it is preferable that the protective layers 131 and 132 have 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.

[0122] The protective layers 131 and 132 may be, for example, a laminated structure of an aluminum oxide film and a silicon nitride film on the aluminum oxide film, or a laminated structure of an aluminum oxide film and an IGZO film on the aluminum oxide film. By using such a laminated structure, impurities (water, oxygen, etc.) can be prevented from penetrating into the EL layer.

[0123] Furthermore, the protective layers 131 and 132 may include an organic film. For example, the protective layer 132 may include both an organic film and an inorganic film.

[0124] Different film formation methods may be used for the protective layer 131 and the protective layer 132. Specifically, the protective layer 131 may be formed by the ALD method, and the protective layer 132 may be formed by the sputtering method.

[0125] Color conversion layers 129 (color conversion layers 129a and 129b) are provided on protective layer 131. Color conversion layer 129a has an area overlapping with light-emitting device 130a, and color conversion layer 129b has an area overlapping with light-emitting device 130b. Color conversion layers 129a and 129b each have an area overlapping with the light-emitting layer of each light-emitting device 130.

[0126] The color conversion layer 129 has the function of converting light emitted by the light-emitting device 130 into light of a different wavelength. Furthermore, the color conversion layer 129a and the color conversion layer 129b have the function of converting light into light of different colors. For example, the color conversion layer 129a has the function of converting blue light emitted by the light-emitting device 130a into red light, and the color conversion layer 129b has the function of converting blue light emitted by the light-emitting device 130b into green light. In the sub-pixel 110c, which does not have a color conversion layer, the blue light emitted by the light-emitting device 130c is extracted. This allows the display device 100 to perform full-color display.

[0127] Phosphors, quantum dots, etc. can be used as the color conversion layer 129. In particular, it is preferable to use quantum dots as the color conversion layer 129. By using quantum dots, the color conversion layer 129 can emit light with a narrow half-width of the emission spectrum and a vivid color. Furthermore, the color reproducibility of the display device can be improved.

[0128] The material constituting the quantum dots is not particularly limited, and examples thereof include Group 14 elements, Group 15 elements, Group 16 elements, compounds consisting of multiple Group 14 elements, compounds of an element belonging to Groups 4 to 14 and a Group 16 element, compounds of a Group 2 element and a Group 16 element, compounds of a Group 13 element and a Group 15 element, compounds of a Group 13 element and a Group 17 element, compounds of a Group 14 element and a Group 15 element, compounds of a Group 11 element and a Group 17 element, iron oxides, titanium oxides, chalcogenide spinels, and semiconductor clusters.

[0129] Specifically, cadmium selenide, cadmium sulfide, cadmium telluride, zinc selenide, zinc oxide, zinc sulfide, zinc telluride, mercury sulfide, mercury selenide, mercury telluride, indium arsenide, indium phosphide, gallium arsenide, gallium phosphide, indium nitride, gallium nitride, indium antimonide, gallium antimonide, aluminum phosphide, aluminum arsenide, aluminum antimonide, lead selenide, lead telluride, lead sulfide, indium selenide, terephthalic acid, Indium sulfide, indium sulfide, gallium selenide, arsenic sulfide, arsenic selenide, arsenic telluride, antimony sulfide, antimony selenide, antimony telluride, bismuth sulfide, bismuth selenide, bismuth telluride, silicon, silicon carbide, germanium, tin, selenium, tellurium, boron, carbon, phosphorus, boron nitride, boron phosphide, boron arsenide, aluminum nitride, aluminum sulfide, barium sulfide, barium selenide, barium telluride, calcium sulfide, selenide Calcium, calcium telluride, beryllium sulfide, beryllium selenide, beryllium telluride, magnesium sulfide, magnesium selenide, germanium sulfide, germanium selenide, germanium telluride, tin sulfide, tin selenide, tin telluride, lead oxide, copper fluoride, copper chloride, copper bromide, copper iodide, copper oxide, copper selenide, nickel oxide, cobalt oxide, cobalt sulfide, iron oxide, iron sulfide, manganese oxide, molybdenum sulfide, vanadium oxide, tungsten oxide, tungsten oxide Examples of the quantum dots include talc, titanium oxide, zirconium oxide, silicon nitride, germanium nitride, aluminum oxide, barium titanate, a compound of selenium, zinc, and cadmium, a compound of indium, arsenic, and phosphorus, a compound of cadmium, selenium, and sulfur, a compound of cadmium, selenium, and tellurium, a compound of indium, gallium, and arsenic, a compound of indium, gallium, and selenium, a compound of indium, selenium, and sulfur, a compound of copper, indium, and sulfur, and combinations thereof. Also, so-called alloy-type quantum dots, whose composition is expressed in any ratio, may be used.

[0130] Quantum dot structures include core, core-shell, and core-multishell types. Quantum dots have a high proportion of surface atoms, making them highly reactive and prone to aggregation. Therefore, it is preferable that a protective agent or protective group is attached to the surface of the quantum dots. By attaching the protective agent or providing the protective group, aggregation can be prevented and solubility in a solvent can be increased. It is also possible to reduce reactivity and improve electrical stability.

[0131] Since the band gap of quantum dots increases as their size decreases, their size can be adjusted appropriately to obtain light of the desired wavelength. As the crystal size decreases, the emission of quantum dots shifts toward the blue side, i.e., toward higher energy, so by changing the size of the quantum dots, the emission wavelength can be adjusted across the wavelength ranges of the ultraviolet, visible, and infrared spectrum. The size (diameter) of quantum dots is, for example, 0.5 nm or more and 20 nm or less, preferably 1 nm or more and 10 nm or less. The narrower the size distribution of quantum dots, the narrower the emission spectrum, resulting in emission with excellent color purity. The shape of quantum dots is not particularly limited and may be spherical, rod-shaped, disc-shaped, or other shapes. Quantum rods, which are rod-shaped quantum dots, have the function of emitting directional light.

[0132] The material for constituting the phosphor is not particularly limited, and inorganic or organic phosphors can be used. For example, rare earth elements, alkali metal elements, alkaline earth metal elements, other metal elements, or semimetal elements can be used. Non-metal elements such as oxygen, nitrogen, sulfur, carbon, hydrogen, and halogen elements can also be included.

[0133] Examples of inorganic phosphors include those containing Eu (europium), Ce (cerium), Y (yttrium), Al (aluminum), Ba (barium), Mg (magnesium), Ca (calcium), Zr (zirconium), Tb (terbium), Sr (strontium), Lu (lutetium), Pr (praseodymium), Gd (gadolinium), Si (silicon), and the like.

[0134] Specifically, as a blue phosphor, for example, BaMgAl 10 O 17 :EU 2+ , CaMgSi2O6:Eu 2+ , Ba3MgSi2O8:Eu 2+ , Sr 10 (PO4)6Cl2:Eu 2+ etc. can be used.

[0135] Furthermore, as a green-blue or blue-green phosphor, for example, Sr4Si3O8Cl4:Eu 2+ , SrAl 14 O 24 :EU 2+ , BaAlO 13 :EU 2+ , Ba2SiO4:Eu 2+ , BaZrSi3O9:Eu 2+ , Ca2YZr2(AlO4)3:Ce 3+ , Ca2YHf2(AlO4)3:Ce 3+ , Ca2YZr2(AlO4)3:Ce 3+ ,Tb 3+ can be used.

[0136] As a green phosphor, for example, (Ba,Sr)2SiO4:Eu 2+ , Ca8Mg(SiO4)4Cl2:Eu 2+ , Ca8Mg(SiO4)4Cl2:Eu 2+ ,Mn 2+ , BaMgAl 10 O 17 :EU 2+ ,Mn 2+ , CeMgAl 11 O 19 :Mn 2+, Y3Al2(AlO4)3:Ce 3+ , Lu3Al2(AlO4)3:Ce 3+ , Y3Ga2(AlO4)3:Ce 3+ , Ca3Sc2Si3O 12 :Ce 3+ , CaSc2O4:Ce 3+ , β-Si3N4:Eu 2+ , SrSi2O2N2:Eu 2+ , Ba3Si6O 12 N2:Eu 2+ , SrSi 13 Al3O2N 21 :EU 2+ , YTbSi4N6C:Ce 3+ , SrGa2S4:Eu 2+ , Ca2LaZr2(AlO4)3:Ce 3+ , Ca2TbZr2(AlO4)3:Ce 3+ , Ca2TbZr2(AlO4)3:Ce 3+ ,Pr 3+ , Zn2SiO4:Mn 2+ , MgGa2O4:Mn 2+ , LaPO4:Ce 3+ ,Tb 3+ , Y2SiO4:Ce 3+ , CeMgAl 11 O 19 :Tb 3+ , GdMgB5O 10 :Ce 3+ ,Tb 3+ can be used.

[0137] As a yellow or orange phosphor, for example, (Sr,Ba)2SiO4:Eu 2+ , (Y,Gd)3Al5O 12 :Ce 3+ , α-Ca-SiAlON:Eu 2+ , Y2Si4N6C:Ce 3+ , La3Si6N 11 :Ce 3+ , Y3MgAl(AlO4)2(SiO4):Ce 3+ can be used.

[0138] The red phosphor is, for example, Sr2Si5N8:Eu 2+ , CaAlSiN3:Eu 2+ , SrAlSi4N7:Eu 2+ , CaS:Eu 2+ , La2O2S:Eu 3+ , Y3Mg2(AlO4)(SiO4)2:Ce 3+ , Y2O3:Eu 3+ , Y2O2S:Eu 3+ , Y(P,V)O4:Eu 3+ , YVO4:Eu 3+ , 3.5MgO·0.5MgF2·GeO2:Mn 4+ , K2SiF6:Mn 4+ , GdMgB5O 10 :Ce 3+ ,Mn 2+ can be used.

[0139] The following materials can be used as the organic fluorescent material.

[0140] Examples of red phosphors include rare earth element ion complexes with anions such as Bronsted acids, β-diketonates, β-diketones, or aromatic carboxylic acids as ligands. Other examples include perylene pigments (e.g., dibenzo{[f,f']-4,4',7,7'-tetraphenyl}diindeno[1,2,3-cd:1',2',3'-lm]perylene), anthraquinone pigments, lake pigments, azo pigments, quinacridone pigments, anthracene pigments, isoindoline pigments, isoindolinone pigments, phthalocyanine pigments, triphenylmethane basic dyes, indanthrone pigments, indophenol pigments, cyanine pigments, and dioxazine pigments.

[0141] Examples of green fluorescent materials include pyridine-phthalimide condensation derivatives, benzoxazinone-based, quinazolinone-based, coumarin-based, quinophthalone-based, and naphthalimide-based fluorescent dyes, and terbium complexes having hexyl salicylate as a ligand.

[0142] Examples of blue phosphors include fluorescent dyes of naphthalimide-based, benzoxazole-based, styryl-based, coumarin-based, pyrazoline-based and triazole-based compounds, and thulium complexes.

[0143] The above phosphors may be used singly or in any combination of two or more in any ratio. By combining the above phosphors, various colors such as white, cyan, magenta, and yellow can be produced.

[0144] Here, adjacent color conversion layers 129 preferably have overlapping regions. Specifically, it is preferable that the regions of the color conversion layers 129 that do not overlap with the light-emitting devices 130 have overlapping regions with adjacent color conversion layers 129. By overlapping the color conversion layers 129 that transmit light of different colors, the color conversion layers 129 can function as light-blocking layers in the overlapping regions. This can prevent light emitted by the light-emitting devices 130 from leaking into adjacent subpixels. For example, it can prevent light emitted by the light-emitting device 130a that overlaps with the color conversion layer 129a from entering the color conversion layer 129b. This can increase the contrast of images displayed on the display device, resulting in a display device with high display quality.

[0145] Note that adjacent color conversion layers 129 do not necessarily have to have overlapping regions. In this case, it is preferable to provide a light-shielding layer in the region where the color conversion layer 129 and the light-emitting device 130 do not overlap. The light-shielding layer can be provided, for example, on the surface of the substrate 120 facing the resin layer 122. Alternatively, the color conversion layer 129 may be provided on the surface of the substrate 120 facing the resin layer 122.

[0146] Furthermore, by forming the color conversion layer 129 on the protective layer 132, it is easier to align each light-emitting device 130 with each color conversion layer 129 than when the color conversion layer 129 is formed on the substrate 120, making it possible to realize an extremely high-definition display device.

[0147] The upper end portions of the pixel electrodes 111a, 111b, and 111c are not covered with an insulating layer, which allows the distance between adjacent light-emitting devices to be extremely narrow, thereby enabling a high-definition or high-resolution display device.

[0148] In this specification, etc., a device fabricated using a metal mask or 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 FMM may be referred to as a device with an MML (metal maskless) structure.

[0149] In addition, in this specification, a light-emitting device capable of emitting blue light may be referred to as a blue light-emitting device. As described above, a blue light-emitting device can be combined with a color conversion layer (e.g., quantum dots) to realize a full-color display device.

[0150] Furthermore, light-emitting devices can be broadly divided into single structures and tandem structures. A single-structure device has one light-emitting unit between a pair of electrodes, and the light-emitting unit preferably includes one or more light-emitting layers. To obtain blue light emission, the device may be configured to have one or more blue light-emitting layers, or multiple light-emitting layers that emit light of a color other than blue may be stacked to produce blue light emission as a whole. Alternatively, the device may be configured to emit blue light as a whole by stacking one or more blue light-emitting layers and multiple light-emitting layers that emit light of a color other than blue.

[0151] A tandem-structure device preferably has a plurality of light-emitting units between a pair of electrodes, each of which includes one or more light-emitting layers. To obtain blue light, light from the light-emitting layers of the plurality of light-emitting units may be combined to obtain blue light. The configuration for obtaining blue light is the same as that of the single-structure device. In a tandem-structure device, it is preferable to provide an intermediate layer, such as a charge-generating layer, between the plurality of light-emitting units.

[0152] Furthermore, the above-mentioned blue light-emitting device (single structure or tandem structure) is preferable because the manufacturing process is simpler than a structure in which light-emitting devices for each color are produced separately (hereinafter sometimes referred to as an SBS (Side By Side) structure), and therefore the manufacturing cost can be reduced or the manufacturing yield can be increased.

[0153] The display device of this embodiment can reduce the distance between light-emitting devices. Specifically, the distance between light-emitting devices, between EL layers, or between pixel electrodes can be less than 10 μm, 5 μm or less, 3 μm or less, 2 μm or less, 1 μm or less, 500 nm or less, 200 nm or less, 100 nm or less, 90 nm or less, 70 nm or less, 50 nm or less, 30 nm or less, 20 nm or less, 15 nm or less, or 10 nm or less. In other words, the distance between the side surface of the first layer 113a and the side surface of the second layer 113b or the distance between the side surface of the second layer 113b and the side surface of the third layer 113c has a region of 1 μm or less, preferably a region of 0.5 μm (500 nm) or less, and more preferably a region of 100 nm or less.

[0154] A light-shielding layer may be provided on the surface of substrate 120 facing resin layer 122. Various optical members may be disposed on the outer surface of substrate 120 (the surface opposite resin layer 122). 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 outer surface of substrate 120 may also be provided with an anti-static 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, etc.

[0155] The substrate 120 can 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 120 can increase the flexibility of the display device. Alternatively, a polarizing plate may be used as the substrate 120.

[0156] The substrate 120 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. The substrate 120 may be made of glass having a thickness sufficient to provide flexibility.

[0157] 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).

[0158] 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.

[0159] 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.

[0160] 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.

[0161] The resin layer 122 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.

[0162] Materials that can be used for conductive layers such as gate electrodes, source electrodes, and drain electrodes of transistors, as well as various wirings and electrodes that constitute display devices 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.

[0163] 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 a display device, and conductive layers (conductive layers functioning as pixel electrodes or common electrodes) in light-emitting devices.

[0164] 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.

[0165] Next, modified examples of the cross-sectional shape of the display device 100 will be described with reference to Figures 2, 3, 34, and 35. Figures 2 and 3 show cross-sectional views taken along dashed lines X1-X2 in Figure 1A. Figures 34 and 35 show cross-sectional views of the connection portion 140 taken along dashed lines X1-X2 and Y1-Y2 in Figure 1A.

[0166] As shown in FIG. 2A, color conversion layers 129a, 129b, and 129c having the function of converting light into different colors may be provided on light-emitting devices 130a, 130b, and 130c, respectively, to form subpixels 110a, 110b, and 110c that emit light of different colors.

[0167] For example, color conversion layer 129a can convert blue light emitted by light-emitting device 130a into yellow (Y) light, color conversion layer 129b can convert blue light emitted by light-emitting device 130b into cyan (C) light, and color conversion layer 129c can convert blue light emitted by light-emitting device 130c into magenta (M) light. However, this is not limiting, and subpixels 110a, 110b, and 110c may each be configured with three colors: red (R), green (G), and blue (B). When subpixel 110c emits blue light, extracting the blue light emitted from light-emitting device 130c via color conversion layer 129c allows the subpixel to emit a brighter blue color with a narrower half-width of the emission spectrum than when the color conversion layer 129c is not used.

[0168] As shown in FIG. 2B, the display device 100 may be configured to include microlenses 134. The display device 100 shown in FIG. 2B includes a first substrate 135 and a second substrate 136. The first substrate 135 includes the layer 101, pixel electrodes 111a, 111b, and 111c, the first layer 113a, the second layer 113b, the third layer 113c, the fifth layer 114, the common electrode 115, protective layers 131 and 132, and insulating layers 125 and 127. The second substrate 136 includes the substrate 120, color conversion layers 129a and 129b, an insulating layer 133, and the microlenses 134.

[0169] With respect to substrate 120, second substrate 136 has color conversion layer 129 provided on substrate 120, insulating layer 133 provided on color conversion layer 129, and microlenses 134 provided on insulating layer 133. Microlenses 134 and color conversion layer 129 are arranged so as to overlap any of the corresponding light-emitting devices 130.

[0170] The microlenses 134 may be made of resin, glass, or the like that is highly transmissive to visible light. The microlenses 134 may be formed separately for each sub-pixel, or may be integrated with multiple sub-pixels. By providing the microlenses 134, it is possible to concentrate the light emitted by the light-emitting device 130 and improve the light extraction efficiency from the display device 100.

[0171] The insulating layer 133 may be an inorganic insulating film or an organic insulating film that can be used for the protective layers 131 and 132. The insulating layer 133 preferably functions as a planarization film, and in this case, an organic insulating film is preferably used as the insulating layer 133. Alternatively, the insulating layer 133 may not be provided.

[0172] The display device 100 shown in FIG. 2B can be formed by bonding a first substrate 135 and a second substrate 136 together with a resin layer 122.

[0173] 1B shows a configuration in which the insulating layer 125 is provided, the present invention is not limited to this, and a configuration in which the insulating layer 125 is not provided may also be used, as shown in FIG. 3A. In this case, it is preferable to use an organic material for the insulating layer 127 that causes little damage to the first layer 113a, the second layer 113b, and the third layer 113c. For example, it is preferable to use an organic material such as polyvinyl alcohol (PVA), polyvinyl butyral, polyvinylpyrrolidone, polyethylene glycol, polyglycerin, pullulan, water-soluble cellulose, or an alcohol-soluble polyamide resin for the insulating layer 127.

[0174] 1B shows a configuration in which the heights of the upper surfaces of insulating layer 125 and insulating layer 127 are the same as or approximately the same as the height of the upper surface of at least one of first layer 113a, second layer 113b, and third layer 113c, respectively, but the present invention is not limited to this. For example, as shown in FIG. 3B, the upper surfaces of insulating layer 125 and insulating layer 127 may be configured to be higher than the upper surfaces of first layer 113a, second layer 113b, and third layer 113c.

[0175] As shown in FIG. 3B , one or both of a first sacrificial layer 118 and a second sacrificial layer 119 may be formed on the first layer 113a, the second layer 113b, or the third layer 113c. For example, the first sacrificial layer 118 is formed on the upper surface of the first layer 113a, the upper surface of the second layer 113b, and the upper surface of the third layer 113c, and the second sacrificial layer 119 is formed on the first sacrificial layer 118. One side of the first sacrificial layer 118 and one side of the second sacrificial layer 119 are in contact with the insulating layer 125. The other side of the first sacrificial layer 118 and the other side of the second sacrificial layer 119 are in contact with the fifth layer 114. The first sacrificial layer 118 and the second sacrificial layer 119 are sacrificial layers used in the manufacturing process of the display device 100, and will be described in detail below.

[0176] Here, a plane (a surface in contact with the fifth layer 114) formed by the side surfaces of the first sacrificial layer 118, the side surfaces of the second sacrificial layer 119, part of the side surfaces of the insulating layer 125, and part of the side surfaces of the insulating layer 127 preferably has a tapered shape in a cross-sectional view. When the plane has a tapered shape in a cross-sectional view, the fifth layer 114 and the common electrode 115 formed to cover the first sacrificial layer 118, the second sacrificial layer 119, the insulating layer 125, and the insulating layer 127 can be formed with good coverage, and discontinuities in the fifth layer 114 and the common electrode 115 can be prevented. Note that in this specification and the like, a tapered shape refers to a shape in which at least part of the side surface of a structure is inclined with respect to the substrate surface or the surface to be formed. For example, it is preferable to have a region in which the angle (also referred to as the taper angle) between the inclined side surface and the substrate surface or the surface to be formed is less than 90 degrees.

[0177] 2B shows a configuration in which microlenses 134 are provided on the substrate 120 side, but the present invention is not limited to this. For example, as shown in FIG. 3C, microlenses 134 may be provided on the layer 101 side. In this case, an insulating layer 133 is provided on the color conversion layer 129, and microlenses 134 are provided on the insulating layer 133. The substrate 120 is bonded by a resin layer 122 provided on the microlenses 134.

[0178] 3A, an example in which the insulating layer 125 is not provided is shown in Fig. 34A. When the insulating layer 125 is not provided, the insulating layer 127 can be configured to be in contact with the side surfaces of the pixel electrodes 111a to 111c, the first layer 113a, the second layer 113b, and the third layer 113c. The insulating layer 127 can be provided so as to fill the spaces between the EL layers of the light-emitting devices.

[0179] 3A and the like shows a laminated structure of protective layer 131 and protective layer 132 as the protective layer, but FIG. 34A and the like shows an example in which protective layer 132 is provided but protective layer 131 is not provided. In this way, the protective layer may have a single layer structure or a laminated structure.

[0180] Furthermore, although FIG. 3A and other figures show an example in which a recess is provided in layer 101, as shown in FIG. 34A and other figures, layer 101 does not necessarily have to have a recess.

[0181] FIG. 34B shows an example in which the insulating layer 127 is not provided.

[0182] 1B, 2A, 2B, 3B, 3C, and the like, the fifth layer 114 and the common electrode 115 are provided over the first layer 113a, the second layer 113b, the third layer 113c, 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 and the EL layer are provided and a region where the pixel electrode and the EL layer are not provided (a region between light-emitting devices). In the display device of 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 fifth layer 114 and the common electrode 115 with respect to the surface on which they are formed. Therefore, poor connection due to a step between the fifth layer 114 and the common electrode 115 can be suppressed. Alternatively, the step can be suppressed from locally thinning the common electrode 115, thereby suppressing an increase in electrical resistance.

[0183] In order to improve the flatness of the surfaces on which the fifth layer 114 and the common electrode 115 are formed, it is preferable that the heights of the upper surfaces of the insulating layers 125 and 127 are the same or approximately the same as the height of the upper surface of at least one of the first layer 113a, the second layer 113b, and the third layer 113c. The upper surface of the insulating layer 127 preferably has a flat shape, and may have a convex portion, a convex curved surface, a concave curved surface, or a concave portion.

[0184] 34A and 34B show a configuration in which the common electrode 115 is electrically connected to the conductive layer 123 via the fifth layer 114 at the connection portion 140 (between the dashed dotted line Y1-Y2), but the embodiment of the present invention is not limited to this. For example, as shown in FIG. 34C, the connection portion 140 may not have the fifth layer 114, and the common electrode 115 may be formed in contact with the upper surface of the conductive layer 123.

[0185] Figure 35 also shows an example in which the edge of the pixel electrode does not coincide with the edge of the first layer 113a to the third layer 113c, in other words, the edge of the pixel electrode does not coincide with the top surface shapes of the first layer 113a to the third layer 113c.

[0186] There is no particular limitation on the size relationship between the pixel electrode 111a and the first layer 113a, the pixel electrode 111b and the second layer 113b, the pixel electrode 111c and the third layer 113c, etc. FIG. 35A shows an example in which the end of the first layer 113a is located inside the end of the pixel electrode 111a. In FIG. 35A, the end of the first layer 113a is located on the pixel electrode 111a. FIG. 35B shows an example in which the end of the first layer 113a is located outside the end of the pixel electrode 111a. In FIG. 35B, the first layer 113a is provided so as to cover the end of the pixel electrode 111a.

[0187] In addition, when the edges are aligned or approximately aligned, and when the top surface shapes are the same or approximately aligned, it can be said that at least a portion of the contours of the stacked layers overlap when viewed from above. 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, it is also said that the edges are approximately aligned, or the top surface shapes are approximately aligned.

[0188] 35C shows a modified example of insulating layer 127. In Fig. 35C, the upper surface of insulating layer 127 has a shape that gradually bulges out toward the center, i.e., a convex curved surface, in a cross-sectional view, and a shape that is recessed in the center and its vicinity, i.e., a concave curved surface.

[0189] Note that the display device of one embodiment of the present invention is not limited to a configuration in which one color is expressed by three subpixels. For example, a configuration in which one color is expressed by four subpixels of R (red), G (green), B (blue), and W (white) may be applied. Figure 4 shows an example in which a pixel is formed by four types of subpixels.

[0190] 4A shows a top view of the 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.

[0191] The pixel 110 shown in FIG. 4A is made up of four types of subpixels: subpixels 110a, 110b, 110c, and 110d.

[0192] For example, the subpixels 110a, 110b, 110c, and 110d may each have a light-emitting device that emits light of a different color. Like the subpixels 110a, 110b, and 110c, the subpixel 110d also has a light-emitting device 130d that emits blue light. For example, the subpixel 110a may have a color conversion layer 129a that can convert blue light to red light, the subpixel 110b may have a color conversion layer 129b that can convert blue light to green light, the subpixel 110c may have a color conversion layer 129c that can convert blue light to white light, and the subpixel 110d may have no color conversion layer. With this configuration, for example, the subpixels 110a, 110b, and 110c may be red, green, and white subpixels, respectively, and the subpixel 110d may be a blue subpixel.

[0193] FIG. 4A shows an example in which one pixel 110 is configured with two rows and three columns. The pixel 110 has three subpixels (subpixels 110a, 110b, and 110c) in the top row (first row) and three subpixels 110d in the bottom row (second row). In other words, the pixel 110 has the subpixels 110a and 110d in the left column (first column), the subpixels 110b and 110d in the center column (second column), and the subpixels 110c and 110d in the right column (third column). By aligning the subpixels in the top row and bottom row as shown in FIG. 4A, it is possible to efficiently remove dust and other particles that may occur during the manufacturing process. This makes it possible to provide a display device with high display quality.

[0194] Figure 4B shows a cross-sectional view taken along dashed line X3-X4 in Figure 4A. The configuration shown in Figure 4B is the same as that shown in Figure 1B, except that it includes a light-emitting device 130d. Therefore, a description of the same parts as those in Figure 1B will be omitted.

[0195] 4B, display device 100 has light-emitting devices 130a, 130b, 130c, and 130d provided on layer 101, and protective layers 131 and 132 provided to cover these light-emitting devices. Substrate 120 is bonded to protective layer 132 by resin layer 122. Insulating layers 125 and 127 are provided in the regions between adjacent light-emitting devices.

[0196] Light-emitting devices 130a, 130b, 130c, and 130d emit blue light. A color conversion layer 129a is provided overlying light-emitting device 130a, a color conversion layer 129b is provided overlying light-emitting device 130b, and a color conversion layer 129c is provided overlying light-emitting device 130c. No color conversion layer is provided on light-emitting device 130d. For example, by configuring color conversion layer 129a to convert blue light to red (R) light, color conversion layer 129b to convert blue light to green (G) light, and color conversion layer 129c to convert blue light to white (W) light, it is possible to achieve a combination that emits light of four colors: red (R), green (G), blue (B), and white (W).

[0197] The light-emitting device 130d includes a pixel electrode 111d on the layer 101, an island-shaped fourth layer 113d on the pixel electrode 111d, a fifth layer 114 on the island-shaped fourth layer 113d, and a common electrode 115 on the fifth layer 114. In the light-emitting device 130d, the fourth layer 113d and the fifth layer 114 can be collectively referred to as an EL layer. The pixel electrode 111d may be made of the same material as the pixel electrodes 111a, 111b, and 111c. The fourth layer 113d may be made of the same material as the first layer 113a, the second layer 113b, and the third layer 113c.

[0198] The three sub-pixels 110d of the pixel 110 may each have an independent light-emitting device 130d, or may share one light-emitting device 130d. In other words, the pixel 110 may have one or three light-emitting devices 130d.

[0199] [Pixel layout] Next, pixel layouts different from those shown in Figures 1A and 4A 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.

[0200] Examples of the top surface shape of the sub-pixel 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 sub-pixel corresponds to the top surface shape of the light-emitting region of the light-emitting device.

[0201] An S-stripe arrangement is applied to the pixel 110 shown in Fig. 5A. The pixel 110 shown in Fig. 5A 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.

[0202] The pixel 110 shown in FIG. 5B 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 designated as a green subpixel G, the subpixel 110b as a red subpixel R, and the subpixel 110c as a blue subpixel B.

[0203] The pixels 124a and 124b shown in Fig. 5C are arranged in a Pentile array. Fig. 5C shows an example in which pixel 124a, which has subpixels 110a and 110b, and pixel 124b, which has subpixels 110b and 110c, are arranged alternately. For example, subpixel 110a may be a red subpixel R, subpixel 110b may be a green subpixel G, and subpixel 110c may be a blue subpixel B.

[0204] 5D and 5E are arranged in a delta configuration. 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). 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, subpixel 110a may be a red subpixel R, subpixel 110b may be a green subpixel G, and subpixel 110c may be a blue subpixel B.

[0205] FIG. 5D shows an example in which each subpixel has a substantially rectangular shape with rounded corners when viewed from above, and FIG. 5E shows an example in which each subpixel has a circular shape when viewed from above.

[0206] 5F 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, subpixel 110a may be the red subpixel R, subpixel 110b may be the green subpixel G, and subpixel 110c may be the blue subpixel B.

[0207] 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.

[0208] Furthermore, in a manufacturing method of a display device according to one embodiment of the present invention, the EL layer is processed into an island shape using a resist mask. The resist film formed on the EL layer needs to be cured at a temperature lower than the heat resistance temperature of the EL layer. Therefore, depending on the heat resistance temperature of the material for the EL layer and the curing temperature of the resist material, the resist film may not be cured sufficiently. A resist film that is not cured sufficiently may have a shape that is different from the desired shape during processing. As a result, the top surface shape of the EL layer may become a polygon with rounded corners, an ellipse, a circle, or the like. For example, when a resist mask with a square top surface shape is formed, a resist mask with a circular top surface shape may be formed, resulting in a circular top surface shape of the EL layer.

[0209] In order to obtain a desired top surface shape for the EL layer, a technique for correcting the mask pattern in advance (OPC (Optical Proximity Correction) technique) may be used so that the design pattern and the transfer pattern match. Specifically, OPC technique adds correction patterns to the corners of the figures on the mask pattern.

[0210] An electronic device including the display device of one embodiment of the present invention may have one or both of a flashlight function using the subpixel W and a lighting function using the subpixel W.

[0211] Here, the white light emitted by the subpixel W may be light with high instantaneous brightness, such as a flashlight or strobe light, or light with high color rendering, such as a reading light. When using white light as a reading light, the color temperature of the white light emission can be lowered. For example, by using white light with an incandescent color (e.g., 2500K or more but less than 3250K) or a warm white color (e.g., 3250K or more but less than 3800K), the light source can be gentle on the user's eyes.

[0212] The strobe light function can be realized by, for example, repeating light emission and non-emission in a short cycle, while the flash light function can be realized by, for example, generating a flash of light by instantaneous discharge utilizing the principle of an electric double layer.

[0213] For example, if the electronic device 70 is provided with a camera function, by utilizing a strobe light function or a flash light function, images can be captured with the electronic device 70 even at night, as shown in FIG. 6A. Here, the display device 100 provided in the electronic device 70 functions as a surface light source, which is less likely to cast shadows on the subject, allowing for beautiful images to be captured. Note that the strobe light function or flash light function can be used at times other than night. When the electronic device 70 is provided with a strobe light function or a flash light function, the color temperature of the white light emission can be increased. For example, the color temperature of the light emitted from the electronic device 70 can be white (3800K or more and less than 4500K), daylight white (4500K or more and less than 5500K), or daylight white (5500K or more and less than 7100K).

[0214] Furthermore, if the flash emits light that is stronger than necessary, areas that are naturally bright or dark may appear all white in the image (so-called whiteout). On the other hand, if the flash is too weak, dark areas may appear all black in the image (so-called blackout). To address this issue, the display device may be configured to detect the brightness around the subject using a light-receiving device (also called a light-receiving element), allowing the light-emitting device of the sub-pixel to adjust the light intensity to an optimal level. In other words, the electronic device 70 can also be said to function as an exposure meter.

[0215] The strobe light function and flashlight function can also be used for crime prevention or self-defense purposes. For example, as shown in FIG. 6B, the electronic device 70 can be made to emit light toward a thug to frighten him. In an emergency, such as when one is attacked by a thug, it can be difficult to remain calm and aim the light of a self-defense light, which has a narrow light-emitting range, toward the thug's face. In contrast, because the display device 100 of the electronic device 70 is a surface light source, the light emitted from the display device 100 can be brought into the thug's field of vision even if the display device 100 is slightly misaligned.

[0216] As shown in FIG. 6B, when the display device 100 provided in the electronic device 70 is used as a flashlight for security or self-defense, it is preferable to increase the brightness compared to the nighttime shooting shown in FIG. 6A. Also, by making the display device 100 emit light intermittently multiple times, it is possible to more easily intimidate an assailant. Furthermore, the electronic device 70 may emit a relatively loud sound, such as a buzzer sound, to call for help from those nearby. Emitting the sound near the assailant's face is preferable because it is possible to intimidate the assailant not only by the light but also by the sound.

[0217] Furthermore, when improving the color rendering of the light emitted from the light-emitting device of subpixel W, it is preferable to increase the number of light-emitting layers included in the light-emitting device or the types of light-emitting materials included in the light-emitting layers, thereby obtaining a broader emission spectrum with intensity over a wider wavelength range, and exhibiting light emission with higher color rendering that is closer to sunlight.

[0218] For example, as shown in FIG. 6C, an electronic device 70 capable of emitting light with high color rendering properties may be used as a reading lamp. In FIG. 6C, the electronic device 70 is fixed to a desk 74 using a support 72. By using such a support 72, the electronic device 70 can be used as a reading lamp. The display device 100 provided in the electronic device 70 functions as a surface light source, so shadows are less likely to be cast on an object (a book in FIG. 6C), and the distribution of reflected light from the object is gentle, so light is less likely to be reflected. This improves the visibility of the object, making it easier to see.

[0219] The configuration of the support 72 is not limited to that shown in Fig. 6C. It is sufficient to provide an appropriate arm or movable portion so as to maximize the range of motion. Also, in Fig. 6C, the support 72 holds the electronic device 70 by sandwiching it, but the present invention is not limited to this. For example, a configuration using a magnet, a suction cup, or the like may be used as appropriate.

[0220] The emission color for the above-mentioned lighting applications is not particularly limited, and the implementer can select one or more optimal emission colors as appropriate, such as white, blue, purple, blue-purple, green, yellow-green, yellow, orange, and red.

[0221] The display device according to one embodiment of the present invention may include a light-receiving device in a pixel.

[0222] [Example of a display device manufacturing method] Next, an example of a manufacturing method of a display device will be described with reference to FIGS. 7 to 14. FIGS. 7A and 7B are top views illustrating a manufacturing method of a display device. FIGS. 8A to 8C show cross-sectional views taken along dashed dotted lines X1-X2 and Y1-Y2 in FIG. 1A side by side. FIGS. 9 to 12 are similar to FIG. 8. FIGS. 13A and 13B show cross-sectional views taken along dashed dotted lines X1-X2 in FIG. 1A. FIG. 13C shows a cross-sectional view taken along dashed dotted line Y1-Y2 in FIG. 1A. FIGS. 14A to 14F show enlarged views illustrating the cross-sectional structure of insulating layer 127 and its surroundings.

[0223] The thin films (insulating films, semiconductor films, conductive films, etc.) that make up display devices can be formed using methods such as sputtering, CVD, vacuum deposition, PLD, and ALD. CVD methods include PECVD and thermal CVD. One type of thermal CVD method is metal organic chemical vapor deposition (MOCVD).

[0224] Furthermore, thin films (insulating films, semiconductor films, conductive films, etc.) that constitute 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.

[0225] 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, as well as chemical vapor deposition (CVD). In particular, functional layers included in the EL layer (e.g., 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 (e.g., vacuum deposition), coating methods (e.g., dip coating, die coating, bar coating, spin coating, spray coating), printing methods (e.g., inkjet printing, screen printing (stencil printing), offset printing (lithographic printing), flexography (relief printing), gravure printing, microcontact printing, etc.), etc.

[0226] Furthermore, when processing the thin film that constitutes the display device, a photolithography method or the like can be used. Alternatively, the thin film may be processed by 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.

[0227] 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.

[0228] 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, and ArF laser light. Exposure can also be performed using 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.

[0229] For etching the thin film, dry etching, wet etching, sandblasting, or the like can be used.

[0230] First, as shown in FIG. 8A, a conductive film 111 is formed on a layer 101.

[0231] Then, a first layer 113A is formed on the conductive film 111, a first sacrificial layer 118A is formed on the first layer 113A, and a second sacrificial layer 119A is formed on the first sacrificial layer 118A.

[0232] 8A, in the cross-sectional view between Y1 and Y2, the end of the first layer 113A on the connection portion 140 side is located more inward (closer to the display portion) than the end of the first sacrificial layer 118A. For example, by using a mask for defining the film formation area (also called an area mask or a rough metal mask to distinguish it from a fine metal mask), it is possible to vary the regions where the first layer 113A, the first sacrificial layer 118A, and the second sacrificial layer 119A are formed. In one embodiment of the present invention, a light-emitting device is formed using a resist mask. However, by combining this with an area mask as described above, a light-emitting device can be fabricated using a relatively simple process.

[0233] The conductive film 111 is a film 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 111. The conductive film 111 can be formed by, for example, sputtering or vacuum evaporation.

[0234] The first layer 113A is a layer that will later become the first layer 113a, the second layer 113b, and the third layer 113c. Therefore, the above-mentioned structures applicable to the first layer 113a, the second layer 113b, and the third layer 113c can be applied. The first layer 113A can be formed by a method such as a vapor deposition method (including a vacuum vapor deposition method), a transfer method, a printing method, an inkjet method, or a coating method. The first layer 113A is preferably formed by a vapor deposition method. When forming a film using a vapor deposition method, a premixed material may be used. Note that in this specification and the like, a premixed material is a composite material in which multiple materials are blended or mixed in advance.

[0235] For the first sacrificial layer 118A and the second sacrificial layer 119A, a film that is highly resistant to the processing conditions of the first layer 113A, etc., specifically a film that has a large etching selectivity with respect to the various EL layers, is used.

[0236] The first sacrificial layer 118A and the second sacrificial layer 119A can be formed by, for example, sputtering, ALD (thermal ALD, PEALD), CVD, or vacuum deposition. The first sacrificial layer 118A, which is formed on and in contact with the EL layer, is preferably formed using a method that causes less damage to the EL layer than the second sacrificial layer 119A. For example, the first sacrificial layer 118A is preferably formed using ALD or vacuum deposition rather than sputtering. The first sacrificial layer 118A and the second sacrificial layer 119A are formed at a temperature lower than the heat-resistant temperature limit of the EL layer (typically, 200°C or lower, preferably 100°C or lower, and more preferably 80°C or lower).

[0237] It is preferable to use a film that can be removed by wet etching for the first sacrificial layer 118A and the second sacrificial layer 119A. By using wet etching, damage to the first layer 113A during processing of the first sacrificial layer 118A and the second sacrificial layer 119A can be reduced compared to when dry etching is used.

[0238] Furthermore, it is preferable to use a film for the first sacrificial layer 118A that has a large etching selectivity with respect to the second sacrificial layer 119A.

[0239] In the process of processing the various sacrificial layers in the method for manufacturing the display device of this embodiment, it is desirable that the layers constituting the EL layer (hole injection layer, hole transport layer, light-emitting layer, hole blocking layer, electron blocking layer, electron transport layer, etc.) are not easily processed, and that the various sacrificial layers are not easily processed in the process of processing the layers constituting the EL layer. It is desirable to select the material and processing method of the sacrificial layer and the processing method of the EL layer taking these factors into consideration.

[0240] In this embodiment, an example is shown in which the sacrificial layer is formed with a two-layer structure of first sacrificial layer 118A and second sacrificial layer 119A, but the sacrificial layer may have a single-layer structure or a stacked structure of three or more layers.

[0241] The first sacrificial layer 118A and the second sacrificial layer 119A may each be, for example, a metal film, an alloy film, a metal oxide film, a semiconductor film, or an inorganic film such as an inorganic insulating film.

[0242] The first sacrificial layer 118A and the second sacrificial layer 119A can be made of a metal material such as gold, silver, platinum, magnesium, nickel, tungsten, chromium, molybdenum, iron, cobalt, copper, palladium, titanium, aluminum, yttrium, zirconium, or tantalum, or an alloy material containing such a metal material. It is particularly preferable to use a low-melting-point material such as aluminum or silver. Using a metal material capable of blocking ultraviolet light for one or both of the first sacrificial layer 118A and the second sacrificial layer 119A can prevent the EL layer from being exposed to ultraviolet light, thereby suppressing deterioration of the EL layer, which is preferable.

[0243] Furthermore, metal oxides such as In-Ga-Zn oxide can be used for the first sacrificial layer 118A and the second sacrificial layer 119A. For example, an In-Ga-Zn oxide film can be formed as the first sacrificial layer 118A or the second sacrificial layer 119A by sputtering. Furthermore, indium oxide, In-Zn oxide, In-Sn oxide, indium titanium oxide (In-Ti oxide), indium tin zinc oxide (In-Sn-Zn oxide), indium titanium zinc oxide (In-Ti-Zn oxide), indium gallium tin zinc oxide (In-Ga-Sn-Zn oxide), etc. can also be used. Alternatively, indium tin oxide containing silicon can also be used.

[0244] Instead of the gallium, an element M (wherein M is one or more elements selected from aluminum, silicon, boron, yttrium, copper, vanadium, beryllium, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, and magnesium) may be used. In particular, it is preferable that M is one or more elements selected from gallium, aluminum, and yttrium.

[0245] Furthermore, the first sacrificial layer 118A and the second sacrificial layer 119A can be made of any of the various inorganic insulating films that can be used for the protective layers 131 and 132. In particular, oxide insulating films are preferable because they have higher adhesion to the EL layer than nitride insulating films. For example, inorganic insulating materials such as aluminum oxide, hafnium oxide, and silicon oxide can be used for the first sacrificial layer 118A and the second sacrificial layer 119A. For example, an aluminum oxide film can be formed as the first sacrificial layer 118A or the second sacrificial layer 119A by the ALD method. Using the ALD method is preferable because it can reduce damage to the underlying layer (particularly the EL layer, etc.).

[0246] For example, the first sacrificial layer 118A may be an inorganic insulating film (e.g., an aluminum oxide film) formed by ALD, and the second sacrificial layer 119A may be a tungsten film formed by sputtering. Alternatively, the second sacrificial layer 119A may be an aluminum film or an In-Ga-Zn oxide film.

[0247] The first sacrificial layer 118A and the second sacrificial layer 119A may be made of a material that is soluble in a chemically stable solvent, at least for the film located on the topmost side of the first layer 113A. In particular, materials that dissolve in water or alcohol are suitable for use as the first sacrificial layer 118A or the second sacrificial layer 119A. When forming a film of such a material, it is preferable to apply the material dissolved in a solvent such as water or alcohol by a wet film formation method, and then perform a heat treatment to evaporate the solvent. In this case, performing the heat treatment under a reduced pressure atmosphere is preferable because it allows the solvent to be removed at a low temperature and in a short time, thereby reducing thermal damage to the EL layer.

[0248] The first sacrificial layer 118A and the second sacrificial layer 119A may be formed using a wet film formation method such as spin coating, dipping, spray coating, inkjet, dispensing, screen printing, offset printing, doctor knife method, slit coating, roll coating, curtain coating, or knife coating.

[0249] The first sacrificial layer 118A and the second sacrificial layer 119A may 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.

[0250] 8B, a resist mask 190a is formed on the second sacrificial layer 119A. The resist mask can be formed by applying a photosensitive resin (photoresist) and then performing exposure and development.

[0251] The resist mask may be made of either a positive resist material or a negative resist material.

[0252] 7A, the resist mask 190a is provided at a position overlapping with 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. Preferably, 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. 7A).

[0253] Note that the resist mask 190a is preferably provided also in a position overlapping with a region that will later become the connection portion 140. This can prevent the region of the conductive film 111 that will later become the conductive layer 123 from being damaged during the manufacturing process of the display device.

[0254] 8C, a resist mask 190a is used to remove a portion of the second sacrificial layer 119A to form the second sacrificial layer 119a. The second sacrificial layer 119a remains in the region that will later become the subpixel 110a, the region that will later become the subpixel 110b, the region that will later become the subpixel 110c, and the region that will later become the connection portion 140.

[0255] When etching the second sacrificial layer 119A, it is preferable to use etching conditions with a high selectivity so that the first sacrificial layer 118A is not removed by the etching. Furthermore, when processing the second sacrificial layer 119A, the EL layer is not exposed, so there is a wider range of processing methods to choose from than when processing the first sacrificial layer 118A. Specifically, even when a gas containing oxygen is used as an etching gas when processing the second sacrificial layer 119A, deterioration of the EL layer can be further suppressed.

[0256] Thereafter, 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 wet etching. At this time, in the region where the resist mask 190a is not provided, the first sacrificial layer 118A is located on the outermost surface and the first layer 113A is not exposed. Therefore, damage to the first layer 113A can be suppressed in the process of removing the resist mask 190a. Furthermore, the range of options for removing the resist mask 190a can be expanded.

[0257] Next, as shown in FIG. 9A, the second sacrificial layer 119a is used as a hard mask to remove a portion of the first sacrificial layer 118A, thereby forming a first sacrificial layer 118a.

[0258] The first sacrificial layer 118A and the second sacrificial layer 119A can be processed by wet etching or dry etching, respectively. The first sacrificial layer 118A and the second sacrificial layer 119A are preferably processed by anisotropic etching.

[0259] Compared to the case of using dry etching, the use of wet etching can reduce damage to the first layer 113A when processing the first sacrificial layer 118A and the second sacrificial layer 119A. When using wet etching, it is preferable to use a chemical solution such as a developer, a tetramethylammonium hydroxide solution (TMAH), diluted hydrofluoric acid, oxalic acid, phosphoric acid, acetic acid, nitric acid, or a mixture thereof.

[0260] When dry etching is used, deterioration of the first layer 113A can be suppressed by not using a gas containing oxygen as an etching gas. When dry etching is used, it is preferable to use a gas containing a noble gas (also called a rare gas) such as CF, C, F, SF, CHF, Cl, HO, BCl, or He as an etching gas.

[0261] For example, when an aluminum oxide film formed by ALD is used as the first sacrificial layer 118A, the first sacrificial layer 118A can be processed by dry etching using CHF3 and He. When a tungsten film formed by sputtering is used as the second sacrificial layer 119A, the second sacrificial layer 119A can be processed by dry etching using CF4 and Cl2.

[0262] Next, as shown in FIG. 9B, the second sacrificial layer 119a and the first sacrificial layer 118a are used as hard masks to remove a portion of the first layer 113A, thereby forming the first layer 113a, the second layer 113b, and the third layer 113c.

[0263] 9B , in the region corresponding to the subpixel 110a, a layered structure of the first layer 113a, the first sacrificial layer 118a, and the second sacrificial layer 119a remains on the conductive film 111. In the region corresponding to the subpixel 110b, a layered structure of the second layer 113b, the first sacrificial layer 118a, and the second sacrificial layer 119a remains on the conductive film 111. In the region corresponding to the subpixel 110c, a layered structure of the third layer 113c, the first sacrificial layer 118a, and the second sacrificial layer 119a remains on the conductive film 111. In addition, in the region corresponding to the connection portion 140, a layered structure of the first sacrificial layer 118a and the second sacrificial layer 119a remains on the conductive film 111.

[0264] Through the above steps, the regions of the first layer 113A, the first sacrificial layer 118A, and the second sacrificial layer 119A that are not overlapped with the resist mask 190a can be removed.

[0265] Note that a part of the first layer 113A may be removed using the resist mask 190a, and then the resist mask 190a may be removed.

[0266] Alternatively, the next step may be performed without removing the resist mask 190a. In this case, when the conductive film 111 is processed in a later step, not only the sacrificial layer but also the resist mask can be used as a mask. Processing the conductive film 111 using the resist mask 190a may make the conductive film 111 easier to process than when only the sacrificial layer is used as a hard mask. For example, the range of options for the processing conditions of the conductive film 111, the material of the sacrificial layer, or the material of the conductive film can be expanded.

[0267] The first layer 113A is preferably processed by anisotropic etching, particularly anisotropic dry etching, or alternatively, wet etching.

[0268] When dry etching is used, deterioration of the first layer 113A can be suppressed by not using a gas containing oxygen as the etching gas.

[0269] Alternatively, an etching gas containing oxygen may be used. When the etching gas contains oxygen, the etching rate can be increased. Therefore, etching can be performed under low power conditions while maintaining a sufficiently high etching rate. This can reduce damage to the first layer 113A. Furthermore, problems such as adhesion of reaction products that occur during etching can be reduced.

[0270] When dry etching is used, it is preferable to use a gas containing one or more of H2, CF4, C4F8, SF6, CHF3, Cl2, H2O, BCl3, or noble gases (also called rare gases) such as He and Ar as the etching gas. Alternatively, it is preferable to use a gas containing one or more of these and oxygen as the etching gas. Alternatively, oxygen gas may be used as the etching gas. Specifically, for example, a gas containing H2 and Ar, or a gas containing CF4 and He may be used as the etching gas. Alternatively, for example, a gas containing CF4, He, and oxygen may be used as the etching gas.

[0271] The side surfaces of the first layer 113a, the second layer 113b, and the third layer 113c are preferably perpendicular or approximately perpendicular to the surface on which they are formed. For example, the angle between the surface on which they are formed and these side surfaces is preferably 60 degrees or more and 90 degrees or less.

[0272] Next, as shown in FIG. 9C, the conductive film 111 is processed using the first sacrificial layer 118a and the second sacrificial layer 119a as a hard mask to form pixel electrodes 111a, 111b, and 111c and a conductive layer 123.

[0273] When processing the conductive film 111, a part of the layer 101 (specifically, the insulating layer located on the outermost surface) may be processed to form a recess. In the following explanation, an example will be given in which a recess is provided in the layer 101, but the layer 101 does not necessarily have to have a recess.

[0274] Here, the conductive layer 123 can be formed by providing the first sacrificial layer 118a and the second sacrificial layer 119a in the connection portion 140. By providing the first sacrificial layer 118a and the second sacrificial layer 119a in the connection portion 140, a region of the conductive film 111 that becomes the conductive layer 123 can be prevented from being damaged during the manufacturing process of the display device.

[0275] The conductive film 111 can be processed by a wet etching method or a dry etching method. The conductive film 111 is preferably processed by anisotropic etching.

[0276] Next, as shown in FIG. 10A, an insulating film 125A is formed to cover the pixel electrodes 111a, 111b, 111c, the conductive layer 123, the first layer 113a, the second layer 113b, the third layer 113c, the first sacrificial layer 118a, and the second sacrificial layer 119a.

[0277] The insulating film 125A can be, for example, an inorganic insulating film such as an oxide insulating 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, 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. Alternatively, a metal oxide film such as an indium gallium zinc oxide film may be used.

[0278] 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 the diffusion of at least one of water and oxygen, or has a function of capturing or fixing (also called gettering) at least one of water and oxygen.

[0279] In this specification and the like, a barrier insulating film refers to an insulating film having barrier properties. In addition, in this specification and the like, the barrier properties refer to a function of suppressing the diffusion of a corresponding substance (also referred to as low permeability), or a function of capturing or fixing (also referred to as gettering) a corresponding substance.

[0280] 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.

[0281] Next, as shown in FIG. 10B, an insulating film 127A is formed on the insulating film 125A.

[0282] 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, phenol 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.

[0283] The method for forming the insulating film 127A is not particularly limited, and it can be formed using a wet film formation method such as spin coating, dipping, spray coating, inkjet, 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.

[0284] The insulating films 125A and 127A are preferably formed by a method that causes less damage to the EL layer. 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 the ALD method. The ALD method is preferable because it can reduce film-forming damage to the EL layer and also enables the formation of a film with high coverage.

[0285] Next, as shown in FIG. 10C , the insulating films 125A and 127A are processed to form the insulating layers 125 and 127. The insulating layer 127 is formed so as to contact the side surfaces of the insulating layer 125 and the upper surfaces of the recesses. The insulating layer 125 (and further the insulating layer 127) is provided so as to cover the side surfaces of the pixel electrodes 111a, 111b, and 111c. This prevents a film (a film constituting the EL layer or a common electrode) to be formed later from contacting the pixel electrodes 111a, 111b, and 111c, which would otherwise cause a short circuit in the light-emitting device. Furthermore, the insulating layers 125 and 127 are preferably provided so as to cover the side surfaces of the first layer 113a, the second layer 113b, and the third layer 113c. This prevents a film to be formed later from contacting the side surfaces of these layers, thereby preventing a short circuit in the light-emitting device. Furthermore, damage to the first layer 113a, the second layer 113b, and the third layer 113c in subsequent steps can be suppressed.

[0286] In particular, it is preferable to provide a recess in a part of layer 101 (specifically, in the insulating layer located on the outermost surface), since this allows the entire side surfaces of pixel electrodes 111a, 111b, and 111c to be covered with insulating layers 125 and 127.

[0287] 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.

[0288] The insulating film 127A is preferably processed by ashing using oxygen plasma, for example.

[0289] The insulating film 125A is preferably processed by dry etching. The insulating film 125A is preferably processed by anisotropic etching. The insulating film 125A can be processed using an etching gas that can be used to process the first sacrificial layer 118A and the second sacrificial layer 119A.

[0290] 11A, the first sacrificial layer 118a and the second sacrificial layer 119a are removed, thereby exposing the first layer 113a on the pixel electrode 111a, the second layer 113b on the pixel electrode 111b, the third layer 113c on the pixel electrode 111c, and the conductive layer 123 at the connection portion 140.

[0291] The height of the upper surface of insulating layer 125 and the height of the upper surface of insulating layer 127 preferably match or approximately match the height of the upper surface of at least one of first layer 113a, second layer 113b, and third layer 113c. The upper surface of insulating layer 127 preferably has a flat shape, and may have protrusions or recesses.

[0292] The sacrificial layer removal process can be performed using the same method as the sacrificial layer processing process. In particular, by using a wet etching method, damage to the first layer 113a, the second layer 113b, and the third layer 113c can be reduced when removing the first sacrificial layer 118a and the second sacrificial layer 119a compared to when using a dry etching method.

[0293] The first sacrificial layer 118a and the second sacrificial layer 119a may be removed in separate steps or in the same step.

[0294] Alternatively, either or both of the first sacrificial layer 118a and the second sacrificial layer 119a may be removed by dissolving them in a solvent such as water or alcohol, such as ethyl alcohol, methyl alcohol, isopropyl alcohol (IPA), or glycerin.

[0295] After removing the first sacrificial layer 118a and the second sacrificial layer 119a, a 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, a 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 it allows drying at a lower temperature.

[0296] Next, as shown in FIG. 11B, a fifth layer 114 is formed to cover the insulating layers 125 and 127, the first layer 113a, the second layer 113b, the third layer 113c, and the conductive layer 123.

[0297] The materials that can be used for the fifth layer 114 are as described above. The fifth layer 114 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 fifth layer 114 may also be formed using a premixed material.

[0298] If the insulating layers 125 and 127 were not provided, any of the pixel electrodes 111a, 111b, and 111c might come into contact with the fifth layer 114. Contact between these layers might cause a short circuit in the light-emitting device, especially if the fifth layer 114 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 113a, the second layer 113b, the third layer 113c, and the pixel electrodes 111a, 111b, and 111c. This prevents the highly conductive fifth layer 114 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.

[0299] 11B, a common electrode 115 is formed on the fifth layer 114. The conductive layer 123 and the common electrode 115 are electrically connected via the fifth layer 114, as shown in FIG.

[0300] The materials that can be used for the common electrode 115 are as described above. The common electrode 115 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.

[0301] Thereafter, protective layer 131 is formed on common electrode 115, and protective layer 132 is formed on protective layer 131. Subsequently, color conversion layers 129a and 129b are formed on protective layer 132 so as to have regions overlapping with pixel electrodes 111a and 111b, respectively.

[0302] The color conversion layer can be formed using a droplet ejection method (for example, an inkjet method), a coating method, an imprint method, various printing methods (screen printing, offset printing), etc. A color conversion film such as a quantum dot film may also be used.

[0303] Next, substrate 120 is attached onto color conversion layers 129a and 129b using resin layer 122, thereby completing display device 100 shown in FIG. 1B.

[0304] The materials and film formation methods that can be used for the protective layers 131 and 132 are as described above. Film formation methods for the protective layers 131 and 132 include vacuum deposition, sputtering, CVD, and ALD. The protective layers 131 and 132 may be films formed using different film formation methods. Furthermore, the protective layers 131 and 132 may each have a single-layer structure or a multilayer structure.

[0305] Note that a mask (also referred to as an area mask, rough metal mask, or the like) for defining a film formation area may be used when forming the common electrode 115. Alternatively, without using the mask for forming the common electrode 115, the process of processing the common electrode 115 and the fifth layer 114 shown in FIGS. 11C and 12A may be performed after the process shown in FIG. 11B, and then the process of forming the protective layer 131 may be performed.

[0306] As shown in FIGS. 11C and 7B, a resist mask 190b is formed on the common electrode 115. At the end on the Y2 side in FIG. 11C, there is a portion where the resist mask 190b is not provided. As shown in FIG. 7B, the resist mask 190b is provided in a region overlapping each subpixel and the connecting portion 140. In other words, the region where the resist mask 190b is not provided is located outside the connecting portion 140.

[0307] 12A, a part of the common electrode 115 and a part of the fifth layer 114 are removed using the resist mask 190b. In this manner, the common electrode 115 and the fifth layer 114 can be processed.

[0308] In the above process, a configuration in which a portion of the insulating layer 127 is removed by ashing or the like to expose the second sacrificial layer 119a and the like (see FIG. 10C ) has been shown, but the present invention is not limited to this. For example, as shown in FIG. 12B , a configuration in which openings are provided in the insulating film 127A at positions overlapping with the pixel electrodes 111a, 111b, and 111c and the conductive layer 123 may be used. For example, by applying a photosensitive resin as the insulating film 127A and then performing exposure and development, a pattern can be formed in which openings are provided at positions overlapping with the pixel electrodes 111a, 111b, and 111c and the conductive layer 123.

[0309] As shown in FIG. 12B, after the insulating film 127A is patterned, the display device 100 can be formed in the same manner as in the steps shown in FIGS. 11B to 12A.

[0310] In this case, however, as shown in FIG. 12B, the upper surface of the insulating layer 127 may be higher than the upper surface of the second sacrificial layer 119a. As a result, when the first sacrificial layer 118a and the second sacrificial layer 119a are removed, portions of these layers may remain. Therefore, as shown in FIG. 12C, even after the common electrode 115 is formed, one or both of the first sacrificial layer 118a and the second sacrificial layer 119 that could not be removed by etching may remain on the first layer 113a, the second layer 113b, the third layer 113c, or the conductive layer 123.

[0311] Here, it is preferable that a plane (the surface in contact with the fifth layer 114) formed by the side surfaces of the first sacrificial layer 118, the side surfaces of the second sacrificial layer 119, part of the side surfaces of the insulating layer 125, and part of the side surfaces of the insulating layer 127 has a tapered shape in a cross-sectional view. When the plane has a tapered shape in a cross-sectional view, the fifth layer 114 and the common electrode 115 formed to cover the first sacrificial layer 118, the second sacrificial layer 119, the insulating layer 125, and the insulating layer 127 can be formed with good coverage, and the fifth layer 114 and the common electrode 115 can be prevented from being discontinuous or the like.

[0312] By forming the display device 100 in this manner, the display device 100 shown in FIG. 3B can be formed.

[0313] 13A, the fifth layer 114 may be omitted, and the common electrode 115 may be formed to cover the insulating layers 125 and 127, the first layer 113a, the second layer 113b, and the third layer 113c. In other words, all layers constituting the EL layer of each light-emitting device of each subpixel may be formed separately. In this case, the EL layers of each light-emitting device are all formed in an island shape.

[0314] Here, contact between any of the pixel electrodes 111a, 111b, and 111c and the common electrode 115 may cause a short circuit in the light-emitting device. 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 113a, the second layer 113b, and the third layer 113c and the pixel electrodes 111a, 111b, and 111c, thereby preventing the common electrode 115 from contacting these layers and preventing a short circuit in the light-emitting device. This improves the reliability of the light-emitting device.

[0315] Furthermore, as shown in FIG. 13B, if a portion of layer 101 (specifically, the insulating layer located on the outermost surface) is not processed when forming pixel electrodes 111a, 111b, and 111c, recesses may not be formed in layer 101.

[0316] 11B, in the cross-sectional view between Y1 and Y2, the end of the fifth layer 114 on the connection section 140 side may be located more inward (toward the display section) than the connection section 140, and the fifth layer 114 may not be provided on the conductive layer 123 (see FIG. 13C). For example, when forming the fifth layer 114, a mask (also referred to as an area mask or rough metal mask) for defining the film formation area may be used. In this case, since the fifth layer 114 is not provided on the conductive layer 123, the conductive layer 123 and the common electrode 115 are directly and electrically connected without the fifth layer 114 interposed therebetween.

[0317] 14A to 14F show the cross-sectional structure of a region 139 including the insulating layer 127 and its surroundings.

[0318] FIG. 14A shows an example in which the first layer 113a and the second layer 113b have different thicknesses. The height of the top surface of the insulating layer 125 on the first layer 113a side is the same as or approximately the same as the top surface of the first layer 113a, and the height of the top surface of the second layer 113b on the second layer 113b side is the same as or approximately the same as the top surface of the second layer 113b. The top surface of the insulating layer 127 has a gentle slope, with the first layer 113a side being higher and the second layer 113b side being lower. In this way, the heights of the insulating layers 125 and 127 are preferably the same as the top surfaces of the adjacent EL layers. Alternatively, the top surface may have a flat portion that is the same as the top surface of one of the adjacent EL layers.

[0319] 14B, the upper surface of insulating layer 127 has a region that is higher than the upper surface of first layer 113a and the upper surface of second layer 113b. As shown in Fig. 14B, the upper surface of insulating layer 127 can be configured so that the center and its vicinity bulge in cross section, that is, have a convex curved shape.

[0320] 14C , the upper surface of insulating layer 127 has a shape that gradually bulges toward the center, i.e., a convex curved surface, and a shape that is recessed in the center and its vicinity, i.e., a concave curved surface, in a cross-sectional view. Insulating layer 127 has a region that is higher than the upper surface of first layer 113a and the upper surface of second layer 113b. In addition, in region 139, the display device has at least one of first sacrificial layer 118 and second sacrificial layer 119, and has a first region where the upper surface of insulating layer 127 is higher than the upper surface of first layer 113a and located outside insulating layer 125, and the first region is located on at least one of first sacrificial layer 118 and second sacrificial layer 119. In addition, in region 139, the display device has at least one of a first sacrificial layer 118 and a second sacrificial layer 119, and has a second region in which the upper surface of insulating layer 127 is higher than the upper surface of second layer 113b and is located outside insulating layer 125, and the second region is located on at least one of the first sacrificial layer 118 and the second sacrificial layer 119.

[0321] 14D, the upper surface of insulating layer 127 has an area that is lower than the upper surfaces of first layer 113a and second layer 113b. In addition, the upper surface of insulating layer 127 has a recessed shape in the center and its vicinity, that is, a shape having a concave curved surface, in a cross-sectional view.

[0322] 14E, the upper surface of insulating layer 125 has a region that is higher than the upper surface of first layer 113a and the upper surface of second layer 113b. That is, insulating layer 125 protrudes from the surface on which fifth layer 114 is to be formed, forming a convex portion.

[0323] When forming the insulating layer 125, for example, if the insulating layer 125 is formed so that the height thereof is aligned or approximately aligned with that of the sacrificial layer, the insulating layer 125 may be formed in a protruding shape as shown in FIG. 14E.

[0324] 14F, the upper surface of insulating layer 125 has an area lower than the upper surfaces of first layer 113a and second layer 113b. That is, insulating layer 125 forms a recess on the surface on which fifth layer 114 is to be formed.

[0325] In this way, the insulating layer 125 and the insulating layer 127 can be applied in various shapes.

[0326] As described above, in the manufacturing method of the display device of this embodiment, the island-shaped EL layer is formed by forming the EL layer on the entire surface and then processing it, rather than by using a metal mask pattern, so that the island-shaped EL layer can be formed with a uniform thickness, thereby realizing a high-definition display device or a display device with a high aperture ratio.

[0327] The first layer 113a, the second layer 113b, and the third layer 113c that constitute the blue light-emitting device can be formed in the same process, which simplifies the manufacturing process of the display device and reduces manufacturing costs.

[0328] 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 EL layer is processed in a state in which the light-emitting layer and the carrier transport layer are stacked. Therefore, the display device has a structure in which damage to the light-emitting layer is reduced. Furthermore, the insulating layer prevents contact between the pixel electrode and the carrier injection layer or the common electrode, thereby preventing a short circuit of the light-emitting device.

[0329] 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.

[0330] (Embodiment 2) In this embodiment, a structural example of a light-emitting device that can be applied to a display device of one embodiment of the present invention will be described with reference to FIGS.

[0331] The display device 500 shown in FIGS. 15A and 15B includes a plurality of light-emitting devices 550B that emit blue light. In FIG. 15, a color conversion layer 545R that converts blue light to red light and a color conversion layer 545G that converts blue light to green light are provided on the light-emitting devices 550B. Here, the color conversion layer 545R and the color conversion layer 545G are preferably provided on the light-emitting devices 550B via a protective layer 540. Note that in FIG. 15, the light-emitting device 550B adjacent to the light-emitting device 550B provided with the color conversion layer 545G does not include a color conversion layer. However, the present embodiment is not limited to this. A color conversion layer that converts blue light to a brighter blue with a narrower half-width may be provided adjacent to the color conversion layer 545G.

[0332] 15A has a light-emitting unit 512B between a pair of electrodes (electrode 501, electrode 502). Electrode 501 functions as a pixel electrode and is provided for each light-emitting device. Electrode 502 functions as a common electrode and is provided in common to multiple light-emitting devices.

[0333] That is, each of the three light-emitting devices 550B shown in Fig. 15A has one light-emitting unit (light-emitting unit 512B). Note that a configuration having one light-emitting unit between a pair of electrodes, such as light-emitting device 550B shown in Fig. 15A, is referred to as a single structure in this specification.

[0334] The light-emitting units 512B shown in FIG. 15A can be formed as island-shaped layers. That is, the light-emitting units 512B shown in FIG. 15A correspond to the first layer 113a, the second layer 113b, or the third layer 113c shown in FIG. 1B, etc. The light-emitting device 550B corresponds to the light-emitting device 130a, the light-emitting device 130b, or the light-emitting device 130c. The electrode 501 corresponds to the pixel electrode 111a, the pixel electrode 111b, or the pixel electrode 111c. The electrode 502 corresponds to the common electrode 115.

[0335] The light-emitting unit 512B includes a layer 521, a layer 522, a light-emitting layer 523Q_1, a light-emitting layer 523Q_2, a light-emitting layer 523Q_3, a layer 524, etc. The light-emitting device 550B also includes a layer 525 between the light-emitting unit 512B and the electrode 502, etc.

[0336] FIG. 15A shows an example in which the light-emitting unit 512B does not have the layer 525, and the layer 525 is provided in common among the light-emitting devices. In this case, the layer 525 can be called a common layer. By providing one or more common layers among the plurality of light-emitting devices in this way, the manufacturing process can be simplified, thereby reducing manufacturing costs. Note that the layer 525 may be provided for each light-emitting device. In other words, the layer 525 may be included in the light-emitting unit 512B.

[0337] The layer 521 includes, for example, a layer containing a substance with a high hole-injecting property (hole-injecting layer). The layer 522 includes, for example, a layer containing a substance with a high hole-transporting property (hole-transporting layer). The layer 524 includes, for example, a layer containing a substance with a high electron-transporting property (electron-transporting layer). The layer 525 includes, for example, a layer containing a substance with a high electron-injecting property (electron-injecting layer).

[0338] Alternatively, a structure in which the layer 521 has an electron-injecting layer, the layer 522 has an electron-transporting layer, the layer 524 has a hole-transporting layer, and the layer 525 has a hole-injecting layer may be used.

[0339] 15A, the layer 521 and the layer 522 are shown separately, but this is not limiting. For example, when the layer 521 has a function as both a hole injection layer and a hole transport layer, or when the layer 521 has a function as both an electron injection layer and an electron transport layer, the layer 522 may be omitted.

[0340] 15A, by selecting light-emitting layers that emit blue light as light-emitting layers 523Q_1, 523Q_2, and 523Q_3, blue light can be emitted from light-emitting device 550B. Note that each light-emitting layer may contain the same light-emitting material or different light-emitting materials. While an example is shown in which light-emitting unit 512B has three light-emitting layers, the number of light-emitting layers is not important, and the light-emitting device may have a configuration of, for example, one layer, two layers, or four or more layers.

[0341] By providing color conversion layers 545R and 545G on such light-emitting device 550B capable of emitting blue light, red light, green light, or blue light can be emitted for each pixel, resulting in a full-color display. Note that, in FIG. 15A and other figures, an example is shown in which color conversion layer 545R converts blue light to red light and color conversion layer 545G converts blue light to green light, and no color conversion layer is provided for pixels that emit blue light, but the present invention is not limited to this. The visible light converted by the color conversion layer may be visible light of at least two or more different colors, and may be appropriately selected from, for example, red, green, blue, cyan, magenta, or yellow.

[0342] Therefore, even if the layers 521, 522, 524, 525, the light-emitting layers 523Q_1, 523Q_2, and 523Q_3 have the same structure (material, film thickness, etc.) in each pixel, full-color display can be achieved by providing a color conversion layer as appropriate. Therefore, the display device according to one embodiment of the present invention does not require a separate light-emitting device for each pixel, which simplifies the manufacturing process and reduces manufacturing costs. However, the present invention is not limited thereto. One or more of the layers 521, 522, 524, 525, the light-emitting layers 523Q_1, 523Q_2, and 523Q_3 may have different structures depending on the pixel.

[0343] A light-emitting device 550B shown in FIG. 15B has a configuration in which two light-emitting units (light-emitting unit 512Q_1 and light-emitting unit 512Q_2) are stacked between a pair of electrodes (electrode 501 and electrode 502) with an intermediate layer 531 interposed therebetween.

[0344] Furthermore, the intermediate layer 531 has a function of injecting electrons into one of the light-emitting unit 512Q_1 and the light-emitting unit 512Q_2 and injecting holes into the other when a voltage is applied between the electrode 501 and the electrode 502. The intermediate layer 531 can also be called a charge generation layer.

[0345] For the intermediate layer 531, a material applicable to an electron injection layer, such as lithium fluoride, can be suitably used. For the intermediate layer 531, a material applicable to a hole injection layer can be suitably used. For the intermediate layer 531, a layer containing a material with high hole transport properties (hole transport material) and an acceptor material (electron acceptor material) can be used. For the intermediate layer 531, a layer containing a material with high electron transport properties (electron transport material) and a donor material can be used. By forming the intermediate layer 531 having such a layer, an increase in driving voltage can be suppressed when light-emitting units are stacked.

[0346] The light-emitting unit 512Q_1 includes a layer 521, a layer 522, a light-emitting layer 523Q_1, a layer 524, etc. The light-emitting unit 512Q_2 includes a layer 522, a light-emitting layer 523Q_2, a layer 524, etc. The light-emitting device 550B also includes a layer 525 between the light-emitting unit 512Q_2 and the electrode 502. The layer 525 can also be considered as part of the light-emitting unit 512Q_2.

[0347] 15B, each light-emitting unit emits blue light, thereby enabling blue light emission from the light-emitting device 550B. Note that the multiple light-emitting units may contain the same light-emitting material or different light-emitting materials.

[0348] A configuration in which multiple light-emitting units are connected in series via an intermediate layer 531, such as light-emitting device 550B shown in FIG. 15B, is referred to as a tandem structure in this specification. Although the term "tandem structure" is used in this specification, the present invention is not limited to this, and the tandem structure may also be referred to as a stack structure, for example. The tandem structure can provide a light-emitting device capable of emitting light with high brightness. Furthermore, compared to a single structure, the tandem structure can reduce the current required to achieve the same brightness, thereby reducing the power consumption of the display device and improving its reliability.

[0349] Although the light-emitting units 512Q_1 and 512Q_2 each have one light-emitting layer, the number of light-emitting layers in each light-emitting unit is not critical. For example, the light-emitting units 512Q_1 and 512Q_2 may have different numbers of light-emitting layers. For example, one light-emitting unit may have two light-emitting layers, and the other light-emitting unit may have one light-emitting layer. Alternatively, one light-emitting unit may have two light-emitting layers, and the other light-emitting unit may have three or more light-emitting layers (specifically, three or four light-emitting layers). A structure in which the light-emitting unit has two light-emitting layers is sometimes referred to as a two-tiered tandem structure, a structure in which the light-emitting unit has three light-emitting layers is sometimes referred to as a three-tiered tandem structure, and a structure in which the light-emitting unit has four light-emitting layers is sometimes referred to as a four-tiered tandem structure. A light-emitting device may also be formed by combining a light-emitting unit with a single structure and a light-emitting unit with a tandem structure (a two-tiered tandem structure, a three-tiered tandem structure, or a four-tiered tandem structure).

[0350] The display device 500 shown in Fig. 16A is an example in which the light-emitting device 550B has a configuration in which three light-emitting units are stacked. In Fig. 16A, the light-emitting device 550B has a light-emitting unit 512Q_3 stacked on the light-emitting unit 512Q_2 with an intermediate layer 531 interposed therebetween. The light-emitting unit 512Q_3 has a layer 522, a light-emitting layer 523Q_3, a layer 524, etc. The light-emitting unit 512Q_3 can have the same configuration as the light-emitting unit 512Q_2.

[0351] When a tandem structure is applied to a light-emitting device, the number of light-emitting units is not particularly limited, and can be two or more.

[0352] FIG. 16B shows an example in which n light emitting units 512Q_1 to 512Q_n (n is an integer of 2 or more) are stacked.

[0353] In this way, by increasing the number of stacked light-emitting units, the luminance obtained from the light-emitting device with the same amount of current can be increased in proportion to the number of stacked light-emitting units.Furthermore, by increasing the number of stacked light-emitting units, the current required to obtain the same luminance can be reduced, and therefore the power consumption of the light-emitting device can be reduced in proportion to the number of stacked light-emitting units.

[0354] Note that the light-emitting material of the light-emitting layer in the display device 500 is not particularly limited. For example, in the display device 500 shown in FIG. 16B, the light-emitting layer 523Q_1 of the light-emitting unit 512Q_1 can include a phosphorescent material, and the light-emitting layer 523Q_2 of the light-emitting unit 512Q_2 can include a fluorescent material. Alternatively, the light-emitting layer 523Q_1 of the light-emitting unit 512Q_1 can include a fluorescent material, and the light-emitting layer 523Q_2 of the light-emitting unit 512Q_2 can include a phosphorescent material. Alternatively, the reliability of the display device can be improved by stacking a plurality of fluorescent light-emitting units.

[0355] Note that the configuration of the light-emitting units is not limited to the above. For example, in the display device 500 shown in FIG. 16B, the light-emitting layer 523Q_1 of the light-emitting unit 512Q_1 may include a TADF material, and the light-emitting layer 523Q_2 of the light-emitting unit 512Q_2 may include either a fluorescent material or a phosphorescent material. By using different light-emitting materials in this way, for example, by combining a highly reliable light-emitting material with a light-emitting material with high luminous efficiency, the drawbacks of each material can be compensated for, resulting in a display device with improved reliability and luminous efficiency.

[0356] Note that in the display device of one embodiment of the present invention, all light-emitting layers may be formed using a fluorescent material, or all light-emitting layers may be formed using a phosphorescent material.

[0357] This embodiment mode can be combined with other embodiment modes as appropriate.

[0358] (Embodiment 3) In this embodiment, a display device of one embodiment of the present invention will be described with reference to FIGS.

[0359] 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.

[0360] [Display device 100A] FIG. 17 shows a perspective view of the display device 100A, and FIG. 18A shows a cross-sectional view of the display device 100A.

[0361] The display device 100A has a configuration in which a substrate 152 and a substrate 151 are bonded together. In Fig. 17, the substrate 152 is clearly indicated by a dashed line.

[0362] The display device 100A has a display unit 162, a circuit 164, wiring 165, etc. Fig. 17 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. 17 can also be said to be a display module having the display device 100A, an IC (integrated circuit), and an FPC.

[0363] The circuit 164 can be, for example, a scanning line driver circuit.

[0364] The wiring 165 has a function of supplying signals and power to the display unit 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.

[0365] 17 shows an example in which an IC 173 is provided on a substrate 151 by a COG method, a COF method, or the like. The IC 173 may be, for example, an IC having a scanning line driving circuit or a signal line driving circuit. The display device 100A and the display module may be configured without an IC. Alternatively, the IC may be mounted on an FPC by a COF method, or the like.

[0366] FIG. 18A shows an example of a cross section of display device 100A, where a part of the area including FPC 172, a part of circuit 164, a part of display unit 162, and a part of the area including the end portion are cut away.

[0367] 18A includes transistor 201, transistor 205, light-emitting devices 130a, 130b, and 130c, and color conversion layers 129a and 129b between substrate 151 and substrate 152. Light-emitting devices 130a, 130b, and 130c emit blue light. Color conversion layers 129a and 129b convert the blue light from light-emitting device 130 into light of different wavelengths.

[0368] Here, when a pixel of a display device has three types of subpixels, that is, subpixels having color conversion layers 129a and 129b that convert light into light of different wavelengths, and subpixels that do not have color conversion layers, the three subpixels may be subpixels of three colors, R, G, and B. Alternatively, a combination of subpixels that emit light of different colors may be subpixels of three colors, such as yellow (Y), cyan (C), and magenta (M). Furthermore, when a display device has four subpixels, the four subpixels may be subpixels of four colors, such as R, G, B, and white (W), or subpixels of R, G, B, and Y.

[0369] The light-emitting devices 130a, 130b, and 130c each have a similar structure to the stacked structure shown in FIG. 1B, except for the configuration of the pixel electrodes. The display device 100A shown in FIG. 18A differs from the display device 100 shown in FIG. 1B in that the light-emitting device 130a has a conductive layer 126a, the light-emitting device 130b has a conductive layer 126b, and the light-emitting device 130c has a conductive layer 126c. For details of the light-emitting devices, refer to Embodiment 1. The side surfaces of the pixel electrodes 111a, 111b, and 111c, the conductive layers 126a, 126b, and 126c, the first layer 113a, the second layer 113b, and the third layer 113c are covered with insulating layers 125 and 127, respectively. A fifth layer 114 is provided on the first layer 113a, the second layer 113b, the third layer 113c, and the insulating layers 125 and 127, and a common electrode 115 is provided on the fifth layer 114. In addition, 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.

[0370] 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. 18A, 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.

[0371] The pixel electrodes 111 a, 111 b, and 111 c are connected to a conductive layer 222 b of the transistor 205 through openings provided in the insulating layer 214, respectively.

[0372] Recesses are formed in the pixel electrodes 111a, 111b, and 111c so as to cover the openings formed in the insulating layer 214. The recesses are preferably filled with a layer 128. It is preferable that a conductive layer 126a is formed over the pixel electrode 111a and the layer 128, a conductive layer 126b is formed over the pixel electrode 111b and the layer 128, and a conductive layer 126c is 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.

[0373] The layer 128 has a function of planarizing the recesses of the pixel electrodes 111a, 111b, and 111c. By providing the layer 128, the unevenness of the surface on which the EL layer is formed can be reduced, and the coverage of the EL layer can be improved. Furthermore, by providing the 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, the 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.

[0374] 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.

[0375] 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, phenolic 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.

[0376] By using a photosensitive resin, the layer 128 can be formed only by the steps of exposure and development, and the influence on the surfaces of the pixel electrodes 111a, 111b, and 111c of dry etching, wet etching, etc. can be reduced. Furthermore, by forming the layer 128 using a negative photosensitive resin, it may be possible to form the layer 128 using the same photomask (exposure mask) as that used to form the openings in the insulating layer 214.

[0377] 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.

[0378] 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.

[0379] 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.

[0380] The pixel electrode includes a material that reflects visible light, and the common electrode includes a material that transmits visible light.

[0381] 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.

[0382] The laminated structure from substrate 151 to insulating layer 214 corresponds to layer 101 in the first embodiment.

[0383] The transistor 201 and the transistor 205 are both formed over a substrate 151. These transistors can be manufactured using the same material and in the same process.

[0384] 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.

[0385] 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.

[0386] 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.

[0387] 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 from the edge of the display device 100A through 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.

[0388] 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 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.

[0389] 18A, 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.

[0390] The transistor 201 and the transistor 205 each include a conductive layer 221 that functions as a gate electrode, an insulating layer 211 that functions as a gate insulating layer, conductive layers 222a and 222b that function as a source electrode and a drain electrode, 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 electrode. 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.

[0391] 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, gate electrodes may be provided above and below a semiconductor layer in which a channel is formed.

[0392] 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 gate electrodes. The two gate electrodes may be connected and supplied with the same signal 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 gate electrodes and a potential for driving to the other.

[0393] 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.

[0394] 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 using metal oxide in a channel formation region (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).

[0395] 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.

[0396] 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.

[0397] 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 compositions in which In:M:Zn=1:1:1 or thereabouts, In:M:Zn=1:1:1.2 or thereabouts, In:M:Zn=2:1:3 or thereabouts, In:M:Zn=3:1:2 or thereabouts, In:M:Zn=4:2:3 or thereabouts, In:M:Zn=4:2:4.1 or thereabouts, In:M:Zn=5:1:3 or thereabouts, In:M:Zn=5:1:6 or thereabouts, In:M:Zn=5:1:7 or thereabouts, In:M:Zn=5:1:8 or thereabouts, In:M:Zn=6:1:6 or thereabouts, and In:M:Zn=5:2:5 or thereabouts, etc. Note that "nearby compositions" includes a range of ±30% of the desired atomic ratio.

[0398] For example, when describing a composition with 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 to 3 and the atomic ratio of Zn is 2 to 4. Furthermore, when describing a composition with 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 greater than 0.1 and less than 2 and the atomic ratio of Zn is greater than 5 and less than 7. Furthermore, when describing a composition with 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 greater than 0.1 and less than 2 and the atomic ratio of Zn is greater than 0.1 and less than 2.

[0399] 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 of structures. Similarly, the transistors included in the display portion 162 may all have the same structure or may have two or more types of structures.

[0400] 18B and 18C show other examples of transistor configurations.

[0401] The transistor 209 and the transistor 210 each include a conductive layer 221 functioning as a gate electrode, 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 electrode, 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. An insulating layer 218 covering the transistor may also be provided.

[0402] 18B shows an example in which the insulating layer 225 covers the top surface and side surface 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 electrode, and the other functions as a drain electrode.

[0403] 18C, 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. 18C. In FIG. 18C, 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 each connected to the low-resistance region 231n through openings in the insulating layer 215.

[0404] 18A, 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 shown in this example has a laminated 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 upper 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.

[0405] It is preferable to provide light-shielding layer 117 on the surface of substrate 152 facing substrate 151. Color conversion layers 129a and 129b may also be provided on the surface of substrate 152 facing substrate 151. In Figure 18A, when viewed from the perspective of substrate 152, color conversion layers 129a and 129b are provided so as to cover part of light-shielding layer 117.

[0406] Various optical members can 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 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, etc.

[0407] By providing the protective layers 131 and 132 that cover the light emitting device, it is possible to prevent impurities such as water from entering the light emitting device, thereby improving the reliability of the light emitting device.

[0408] 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 through the organic insulating film. This can therefore improve the reliability of the display device 100A.

[0409] 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.

[0410] Substrates 151 and 152 can be made of polyester resins such as polyethylene terephthalate (PET) and 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.

[0411] 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).

[0412] 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.

[0413] 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.

[0414] 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.

[0415] 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.

[0416] The connection layer 242 may be made of an anisotropic conductive film (ACF), an anisotropic conductive paste (ACP), or the like.

[0417] Materials that can be used for conductive layers such as gate electrodes, source electrodes, and drain electrodes of transistors, as well as various wirings and electrodes that constitute display devices 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.

[0418] 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 a display device, and conductive layers (conductive layers functioning as pixel electrodes or common electrodes) in light-emitting devices.

[0419] 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.

[0420] [Display device 100B] The display device 100B shown in Fig. 19 differs from the display device 100A mainly in that it is a bottom-emission type. Descriptions of parts that are the same as those of the display device 100A will be omitted. While Fig. 19 shows a subpixel including a first layer 113a and a subpixel including a second layer 113b, three or more types of subpixels can be provided, as in Fig. 18.

[0421] Light emitted from the light emitting device is emitted toward the substrate 151. It is preferable that a material that is highly transparent to visible light is used for the substrate 151. On the other hand, the light-transmitting property of the material used for the substrate 152 is not an issue.

[0422] In the display device 100B, the pixel electrodes 111a and 111b and the conductive layers 126a and 126b contain a material that transmits visible light, and the common electrode 115 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 and 111b and the conductive layers 126a and 126b, also contains a material that transmits visible light.

[0423] It is preferable to form a light-shielding layer 117 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 on the substrate 151, the insulating layer 153 is provided on the light-shielding layer 117, and the transistors 201, 205, etc. are provided on the insulating layer 153.

[0424] Furthermore, in display device 100B, color conversion layers 129a and 129b are provided between insulating layer 215 and insulating layer 214. It is preferable that color conversion layers 129a and 129b overlap light-shielding layer 117 at their ends.

[0425] 20A to 20D 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. 20A to 20D.

[0426] 18A and 19 show an example in which the top surface of layer 128 and the top surface of pixel electrode 111a are roughly aligned, but the present invention is not limited to this. For example, as shown in Fig. 20A, the top surface of layer 128 may be higher than the top surface of pixel electrode 111a. In this case, the top surface of layer 128 has a gently bulging shape that is convex toward the center.

[0427] 20B, 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 shape that is concave toward the center.

[0428] 20C, 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.

[0429] 20D, in the structure shown in Fig. 20C, 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.

[0430] This embodiment mode can be combined with other embodiment modes as appropriate.

[0431] (Fourth embodiment) In this embodiment, a display device of one embodiment of the present invention will be described with reference to FIGS.

[0432] The display device of the present embodiment can be a high-definition display device, and can therefore be used as a display unit of information terminals (wearable devices) such as wristwatches and bracelets, as well as head-mounted wearable devices such as VR (Virtual Reality) devices and eyeglass-type AR (Augmented Reality) devices.

[0433] [Display module] 21A 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 the display devices 100D to 100G described below.

[0434] The display module 280 has a substrate 291 and a substrate 292. The display module 280 has a display unit 281. The display unit 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 unit 284 (described later) can be viewed.

[0435] 21B is a perspective view schematically showing the configuration on the substrate 291 side. A circuit section 282, a pixel circuit section 283 on the circuit section 282, and a pixel section 284 on the pixel circuit section 283 are stacked on the substrate 291. A terminal section 285 for connecting to an FPC 290 is provided in a portion of the substrate 291 that does not overlap with the pixel section 284. The terminal section 285 and the circuit section 282 are electrically connected by a wiring section 286 composed of a plurality of wirings.

[0436] 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. 21B. 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 subpixels can be arranged in a stripe array as shown in FIG. 21B. Various light-emitting device arrangement methods, such as a delta array or a pentile array, can also be applied.

[0437] The pixel circuit section 283 has a plurality of pixel circuits 283a arranged periodically.

[0438] 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 capacitance element for each light-emitting device. In this case, a gate signal is input to the gate electrode of the selection transistor, and a source signal is input to either the source electrode or the drain electrode. This realizes an active matrix display device.

[0439] The circuit portion 282 includes a circuit for driving each pixel circuit 283a of the pixel circuit portion 283. For example, it is preferable that the circuit portion 282 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.

[0440] The FPC 290 functions as wiring for supplying a video signal, a power supply potential, or the like from the outside to the circuit section 282. An IC may also be mounted on the FPC 290.

[0441] 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 set to 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 are 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 20000 ppi or less, or 30000 ppi or less.

[0442] Such a display module 280 has extremely high resolution and can therefore be suitably used in VR devices such as head-mounted displays or eyeglass-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 that even if the display unit is enlarged with the 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 having relatively small display units. For example, it can be suitably used in the display unit of a wearable electronic device such as a wristwatch.

[0443] [Display device 100C] 22 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 and a color conversion layer 129a, the subpixel 110b includes a light-emitting device 130b and a color conversion layer 129b, and the subpixel 110c includes a light-emitting device 130c, but does not include a color conversion layer. However, a color conversion layer overlapping the light-emitting device 130c may be provided in the subpixel 110c.

[0444] 21A and 21B. The layered structure from substrate 301 to insulating layer 255b corresponds to layer 101 in the first embodiment.

[0445] 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 either a source or a drain. The insulating layer 314 is provided to cover a side surface of the conductive layer 311 and functions as an insulating layer.

[0446] Furthermore, an element isolation layer 315 is provided between two adjacent transistors 310 so as to be embedded in the substrate 301 .

[0447] In addition, an insulating layer 261 is provided to cover the transistor 310 , and a capacitor 240 is provided on the insulating layer 261 .

[0448] Capacitor 240 has conductive layer 241, conductive layer 245, and insulating layer 243 positioned therebetween. Conductive layer 241 functions as one electrode of capacitor 240, conductive layer 245 functions as the other electrode of capacitor 240, and insulating layer 243 functions as a dielectric of capacitor 240.

[0449] 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.

[0450] 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, 130c have the layered structure shown in FIG. 1B. Side surfaces of the pixel electrodes 111a, 111b, 111c, the first layer 113a, the second layer 113b, and the third layer 113c are covered with insulating layers 125 and 127, respectively. A fifth layer 114 is provided on the first layer 113a, the second layer 113b, the third layer 113c, and the insulating layers 125 and 127, and a common electrode 115 is provided on the fifth layer 114. Furthermore, protective layer 131 is provided on light-emitting devices 130a, 130b, and 130c. Protective layer 132 is provided on protective layer 131, and color conversion layers 129a and 129b are provided on protective layer 132. Substrate 120 is bonded to color conversion layers 129a and 129b via resin layer 122. For details about the components from the light-emitting devices to substrate 120, refer to embodiment 1. Substrate 120 corresponds to substrate 292 in FIG. 21A.

[0451] 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 insulating oxynitride film, and an insulating nitride oxide film. The insulating layer 255a is preferably formed using an insulating oxide film or an insulating oxynitride 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 an insulating nitride oxide 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 insulating oxide insulating film or an oxynitride insulating film. Although this embodiment illustrates an example in which a recess is provided in the insulating layer 255b, the insulating layer 255b does not necessarily have a recess.

[0452] 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.

[0453] [Display device 100D] 23 differs from the display device 100C mainly in the configuration of the transistors. Note that a description of the same parts as those of the display device 100C may be omitted.

[0454] 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.

[0455] 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 .

[0456] 21A and 21B. The layered structure from the substrate 331 to the insulating layer 255b corresponds to the layer 101 in Embodiment 1. The substrate 331 can be an insulating substrate or a semiconductor substrate.

[0457] 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 is preferably 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.

[0458] 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.

[0459] 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.

[0460] A pair of conductive layers 325 is provided over and in contact with the semiconductor layer 321 and functions as a source electrode and a drain electrode.

[0461] 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.

[0462] An opening reaching the semiconductor layer 321 is provided in the insulating layer 328 and the insulating layer 264. An insulating layer 323 and a conductive layer 324 are buried inside the opening and are in contact with the side surfaces of the insulating layer 264, the insulating layer 328, and the conductive layer 325 and the top surface of the semiconductor layer 321. The conductive layer 324 functions as a second gate electrode, and the insulating layer 323 functions as a second gate insulating layer.

[0463] The upper 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.

[0464] 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.

[0465] 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 in the insulating layer 265, the insulating layer 329, the insulating layer 264, and the insulating layer 328 and part of the top surface of the conductive layer 325, and a conductive layer 274b in contact with the top surface of the conductive layer 274a. In this case, the conductive layer 274a is preferably made of a conductive material through which hydrogen and oxygen do not easily diffuse.

[0466] In the display device 100D, the configuration from the insulating layer 254 to the substrate 120 is the same as that of the display device 100C.

[0467] [Display device 100E] 24 has a stacked structure of a transistor 310 having a channel formed in a substrate 301 and a transistor 320 having a channel formed in a semiconductor layer containing a metal oxide. Note that descriptions of parts similar to those of the display devices 100C and 100D may be omitted.

[0468] 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 a 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.

[0469] The transistor 320 can be used as a transistor included in a pixel circuit. The transistor 310 can be used as a transistor included in a pixel circuit or a driver circuit (gate line driver circuit, source line driver circuit) for driving the pixel circuit. The transistors 310 and 320 can be used as transistors included in various circuits such as an arithmetic circuit or a memory circuit.

[0470] 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.

[0471] [Display device 100F] A display device 100F shown in FIG. 25 has a stacked structure of a transistor 310A and a transistor 310B, each of which has a channel formed in a semiconductor substrate.

[0472] 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.

[0473] Here, it is preferable to provide an insulating layer 345 on the lower surface of substrate 301B. It is also preferable to provide an insulating layer 346 on insulating layer 261 provided on substrate 301A. Insulating layers 345 and 346 function as protective layers and can suppress the diffusion of impurities into substrates 301B and 301A. Insulating layers 345 and 346 can be made of an inorganic insulating film that can be used for protective layers 131 and 132 or insulating layer 332 shown in FIG. 24.

[0474] A plug 343 penetrating the substrate 301B and an insulating layer 345 is provided in the substrate 301B. Preferably, an insulating layer 344 is provided to cover the side surface of the plug 343. The insulating layer 344 functions as a protective layer and can suppress the diffusion of impurities into the substrate 301B. The insulating layer 344 can be an inorganic insulating film that can be used for the protective layers 131 and 132 or the insulating layer 332 shown in FIG. 24.

[0475] Furthermore, a conductive layer 342 is provided on the back surface of substrate 301B (the surface opposite to substrate 120) below insulating layer 345. Conductive layer 342 is preferably provided so as to be embedded in insulating layer 335. Furthermore, the lower surfaces of conductive layer 342 and insulating layer 335 are preferably flattened. Here, conductive layer 342 is electrically connected to plug 343.

[0476] 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. Furthermore, the upper surfaces of the conductive layer 341 and the insulating layer 336 are preferably flattened.

[0477] The substrates 301A and 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 bonded well.

[0478] It is preferable to use the same conductive material for conductive layer 341 and conductive layer 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 conductive layer 341 and conductive layer 342. This allows the use of Cu-Cu (copper-copper) direct bonding technology (technology that achieves electrical conductivity by connecting Cu (copper) pads together).

[0479] [Display device 100G] 25 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. 26, in display device 100G, conductive layer 341 and conductive layer 342 may be bonded via bump 347.

[0480] As shown in FIG. 26, 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. Furthermore, when the bump 347 is provided, the insulating layer 335 and the insulating layer 336 shown in FIG. 25 may not be provided.

[0481] This embodiment mode can be combined with other embodiment modes as appropriate.

[0482] (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, particularly the case where a transistor containing silicon as a semiconductor in which a channel is formed will be described.

[0483] One embodiment of the present invention is a display device including a light-emitting device and a pixel circuit. The display device includes, for example, a light-emitting device that emits blue light and a color conversion layer that converts the wavelength of light from the light-emitting device, and has three types of sub-pixels that emit red (R), green (G), and blue (B) light, respectively, to realize a full-color display device.

[0484] It is preferable that all transistors included in a pixel circuit that drives a light-emitting device use transistors that have silicon in a semiconductor layer where a channel is formed. Examples of silicon include single-crystal silicon, polycrystalline silicon, and amorphous silicon. In particular, it is preferable to use transistors that have low-temperature polysilicon (LTPS) in the semiconductor layer (hereinafter also referred to as LTPS transistors). LTPS transistors have high field-effect mobility and good frequency characteristics.

[0485] 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.

[0486] At least one of the transistors included in the pixel circuit preferably uses 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 an amorphous silicon transistor. 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 retain 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.

[0487] 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. A configuration in which an LTPS transistor and an OS transistor are combined is sometimes referred to as LTPO. As a more preferred example, it is preferable to use an OS transistor as a transistor that functions as a switch for controlling conduction / non-conduction between wirings and an LTPS transistor as a transistor for controlling current.

[0488] For example, one of the transistors provided in the pixel circuit functions as a transistor for controlling the current flowing through the light-emitting device and can be called a driving transistor. One of the source and drain of the driving transistor is electrically connected to the 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.

[0489] 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 the pixel to be maintained even when the frame frequency is significantly reduced (for example, 1 fps or less), so power consumption can be reduced by stopping the driver when displaying a still image.

[0490] A more specific configuration example will be described below with reference to the drawings.

[0491] [Display device configuration example 2] 27A 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.

[0492] 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 and a color conversion layer.

[0493] The pixel 30 is electrically connected to the wiring GL, the wiring SLR, the wiring SLG, and the wiring SLB. The wiring SLR, the wiring SLG, and the wiring SLB are each electrically connected to the drive circuit unit 12. The wiring GL is electrically connected to the drive circuit unit 13. The drive circuit unit 12 functions as a source line drive circuit (also referred to as a source driver), and the drive circuit unit 13 functions as a gate line drive circuit (also referred to as a gate driver). The wiring GL functions as a gate line, and the wiring SLR, the wiring SLG, and the wiring SLB each function as a source line.

[0494] Subpixel 21R has a light-emitting device that emits blue light and a color conversion layer that converts the blue light to light with a red wavelength. Subpixel 21G has a light-emitting device that emits blue light and a color conversion layer that converts the blue light to light with a green wavelength. Subpixel 21B has a light-emitting device that emits blue light and a color conversion layer that converts the blue light to a brighter blue. This allows display device 10 to display full color. Note that subpixel 21B may not have a color conversion layer. Alternatively, pixel 30 may have subpixels that emit light of other colors. For example, pixel 30 may have a subpixel that emits white light or a subpixel that emits yellow light in addition to the above three subpixels.

[0495] 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 (none of which are shown) arranged in the column direction (extension direction of the wiring SLR, etc.), respectively.

[0496] [Pixel circuit configuration example] 27B 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. The pixel 21 is also electrically connected to a line GL and a line SL. The line SL corresponds to any one of the line SLR, line SLG, and line SLB shown in FIG. 27A.

[0497] 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.

[0498] 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 the transistor M1 and the transistor M3 and a potential that turns off the transistor M1 and the transistor M3.

[0499] 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.

[0500] 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.

[0501] 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.

[0502] Alternatively, OS transistors may be used for all of the transistors M1 to M3. In this case, the display device 10 shown in FIG. 27A may be configured such that one or more of the transistors included in the driver circuit unit 12 and the driver circuit unit 13 are LTPS transistors, and the remaining transistors are OS transistors. For example, OS transistors may be used for the transistors provided in the display unit 11, and LTPS transistors may be used for the transistors provided in the driver circuit unit 12 and the driver circuit unit 13.

[0503] The OS transistor may be a transistor including an oxide semiconductor in a semiconductor layer in which a channel is formed. 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.

[0504] 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.

[0505] In FIG. 27B, all the transistors are shown as n-channel transistors, but p-channel transistors can also be used.

[0506] Moreover, it is preferable that the transistors included in the pixel 21 are formed side by side on the same substrate.

[0507] The transistor included in the pixel 21 can be a transistor having a pair of gates that overlap with each other with a semiconductor layer interposed therebetween.

[0508] 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.

[0509] 27C 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.

[0510] 27D 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, making it easier to control the emission luminance of the light-emitting device EL, and display quality can be improved.

[0511] [Transistor configuration example] An example of a cross-sectional structure of a transistor that can be applied to the display device will be described below.

[0512] [Configuration example 1] FIG. 28A is a cross-sectional view including a transistor 410.

[0513] The transistor 410 is provided on the substrate 401 and uses polycrystalline silicon for the semiconductor layer. For example, the transistor 410 corresponds to the transistor M2 of the pixel 21 shown in Fig. 27. That is, Fig. 28A shows an example in which one of the source electrode and the drain electrode of the transistor 410 is electrically connected to the conductive layer 431 of the light-emitting device.

[0514] 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. Part of the insulating layer 412 functions as a gate insulating layer. The conductive layer 413 functions as a gate electrode.

[0515] 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.

[0516] 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.

[0517] 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.

[0518] 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. Part of the conductive layer 414a functions as one of the source and drain electrodes, and part of the conductive layer 414b functions as the other of the source and drain electrodes. An insulating layer 423 is provided to cover the conductive layer 414a, the conductive layer 414b, and the insulating layer 422.

[0519] 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 through 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.

[0520] [Configuration example 2] 28B shows a transistor 410a having a pair of gate electrodes, which differs from the transistor 410a shown in FIG. 28A mainly in that a conductive layer 415 and an insulating layer 416 are included.

[0521] 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.

[0522] 28B, the conductive layer 413 functions as a first gate electrode, and part of the conductive layer 415 functions as a second gate electrode. In this case, 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.

[0523] 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 electrode or the drain electrode 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.

[0524] When LTPS transistors are used for all of the transistors constituting pixel 21, it is possible to use transistor 410 illustrated in Fig. 28A or transistor 410a illustrated in Fig. 28B. In this case, transistor 410a may be used for all of the transistors constituting pixel 21, transistor 410 may be used for all of the transistors, or transistor 410a and transistor 410 may be used in combination.

[0525] [Configuration Example 3] An example of a structure including both a transistor in which silicon is used for a semiconductor layer and a transistor in which metal oxide is used for a semiconductor layer will be described below.

[0526] FIG. 28C shows a cross-sectional schematic diagram including transistor 410a and transistor 450.

[0527] The transistor 410a can be the same as in Structure Example 2. Note that although the example using the transistor 410a is described here, 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.

[0528] The transistor 450 is a transistor in which a metal oxide is used for a semiconductor layer. The configuration shown in Fig. 28C is an example in which the transistor 450 corresponds to the transistor M1 of the pixel 21 shown in Fig. 27, and the transistor 410a corresponds to the transistor M2. That is, Fig. 28C shows an example in which one of the source electrode and the drain electrode of the transistor 410a is electrically connected to the conductive layer 431.

[0529] FIG. 28C shows an example in which transistor 450 has a pair of gate electrodes.

[0530] 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. The conductive layer 453 functions as a first gate electrode of the transistor 450, and part of the conductive layer 455 functions as a second gate electrode 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.

[0531] 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.

[0532] 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. Part of the conductive layer 454a functions as one of the source and drain electrodes, and part of the conductive layer 454b functions as the other of the source and drain electrodes. An insulating layer 423 is provided to cover the conductive layer 454a, the conductive layer 454b, and the insulating layer 426.

[0533] 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 28C shows a structure 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.

[0534] 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. Figure 28C shows a structure in which 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.

[0535] In FIG. 28C, 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 FIG. 28D, the insulating layer 452 may be processed so that the top surface shape thereof matches or approximately matches the conductive layer 453.

[0536] 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.

[0537] 27 and is electrically connected to the pixel electrode. However, 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.

[0538] This embodiment mode can be combined with other embodiment modes as appropriate.

[0539] (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.

[0540] 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.

[0541] The metal oxide can be formed by a sputtering method, a CVD method such as an MOCVD method, or an ALD method.

[0542] <Classification of crystal structures> Examples of the crystalline structure of oxide semiconductors include amorphous (including completely amorphous), C-Axis-Aligned Crystalline (CAAC), nanocrystalline (nc), Cloud-Aligned Composite (CAC), single crystal, and polycrystal.

[0543] The crystalline structure of a film or substrate can be evaluated using X-ray diffraction (XRD) spectra. For example, it can be evaluated using XRD spectra obtained by GIXD (Grazing-Incidence XRD) measurements. The GIXD method is also called the thin film method or the Seemann-Bohlin method.

[0544] For example, the peak shape of the XRD spectrum of a quartz glass substrate is nearly symmetrical. On the other hand, the peak shape of the XRD spectrum of an IGZO film, which has a crystalline structure, is asymmetrical. The asymmetrical peak shape of the XRD spectrum clearly indicates the presence of crystals in the film or substrate. In other words, if the peak shape of the XRD spectrum is not symmetrical, the film or substrate cannot be said to be in an amorphous state.

[0545] The crystalline structure of a film or substrate can also be evaluated by the diffraction pattern (also called the nanobeam electron diffraction pattern) observed using nanobeam electron diffraction (NBED). For example, a halo is observed in the diffraction pattern of a quartz glass substrate, confirming that the quartz glass is in an amorphous state. Furthermore, a spot-like pattern is observed in the diffraction pattern of an IGZO film deposited at room temperature, rather than a halo. For this reason, it is estimated that an IGZO film deposited 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.

[0546] <<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 divided 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, amorphous-like oxide semiconductors (a-like OSs), amorphous oxide semiconductors, and the like.

[0547] Here, the above-mentioned CAAC-OS, nc-OS, and a-like OS will be described in detail.

[0548] [CAAC-OS] CAAC-OS is an oxide semiconductor having multiple crystalline regions, each with its c-axis aligned in a specific direction. The specific direction can be the thickness direction of the CAAC-OS film, the normal direction to the surface on which the CAAC-OS film is formed, or the normal direction to the surface of the CAAC-OS film. A crystalline region is a region with periodic atomic arrangement. If the atomic arrangement is considered as a lattice arrangement, a crystalline region can also be a region with a uniform lattice arrangement. Furthermore, CAAC-OS has a region where multiple crystalline regions are connected in the ab-plane direction, and the region may have distortion. Note that distortion refers to a location where the lattice arrangement changes between a region with a uniform lattice arrangement and a region with a different uniform lattice arrangement in the region where multiple crystalline regions are connected. In other words, CAAC-OS is an oxide semiconductor with a c-axis aligned but no clear orientation in the ab-plane direction.

[0549] 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 one 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 nm.

[0550] In an In-M-Zn oxide (wherein M is one or more elements selected from aluminum, gallium, yttrium, tin, titanium, etc.), 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 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 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.

[0551] When the CAAC-OS film is subjected to structural analysis using, for example, an XRD apparatus, a peak indicating c-axis orientation is detected at or near 2θ=31° in out-of-plane XRD measurement using θ / 2θ scan. Note that the position of the peak indicating c-axis orientation (2θ value) may vary depending on the type and composition of the metallic elements constituting the CAAC-OS.

[0552] For example, in the electron diffraction pattern of a CAAC-OS film, multiple bright spots are observed, and the spots are observed at positions that are point-symmetric with respect to the spot of the incident electron beam that has passed through the sample (also called the direct spot).

[0553] When the crystalline region is observed from the specific direction, the lattice arrangement within the crystalline region is basically a hexagonal lattice, but the unit cell is not necessarily a regular hexagon and may be non-regular hexagonal. Furthermore, the distortion may have a pentagonal, heptagonal, or other lattice arrangement. In the CAAC-OS, no clear grain boundaries are observed even near the distortion. This indicates that the formation of grain boundaries is suppressed by the distortion of the lattice arrangement. This is thought to be because the CAAC-OS can tolerate distortion due to the lack of close-packed oxygen atom arrangement in the ab-plane direction and the change in interatomic bond distance caused by metal atom substitution.

[0554] A crystal structure with clear grain boundaries is called polycrystalline. Grain boundaries act as recombination centers, trapping carriers and potentially causing a decrease in the on-state current and field-effect mobility of a transistor. Therefore, CAAC-OS, which lacks clear grain boundaries, is one of the crystalline oxides with a crystal structure suitable for use in the semiconductor layer of a transistor. Zn is preferred for use in 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.

[0555] 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 impurities or defects, the CAAC-OS can be said to be an oxide semiconductor with few impurities and defects (such as oxygen vacancies). Therefore, oxide semiconductors with CAAC-OS have stable physical properties. Therefore, oxide semiconductors with CAAC-OS are heat-resistant and highly reliable. Furthermore, the CAAC-OS is stable even under high temperatures (so-called thermal budgets) during the manufacturing process. Therefore, using a CAAC-OS for an OS transistor can increase the flexibility of the manufacturing process.

[0556] [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 microcrystalline structures. The size of the microcrystalline structures is, for example, 1 nm to 10 nm, particularly 1 nm to 3 nm, and therefore these microcrystalline structures are also called nanocrystalline structures. Furthermore, the nc-OS exhibits no regularity in the crystal orientation between different nanocrystalline structures. Therefore, the entire film lacks orientation. Therefore, depending on the analytical 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 peaks indicating crystallinity are detected in out-of-plane XRD measurements using θ / 2θ scanning. Furthermore, when an nc-OS film is subjected to electron diffraction (also known as selected-area electron diffraction) using an electron beam with a probe diameter larger than that of nanocrystalline structures (e.g., 50 nm or larger), a halo-like diffraction pattern is observed. On the other hand, when electron diffraction (also called nanobeam electron diffraction) is performed on an nc-OS film using an electron beam with a probe diameter close to or smaller than the size of the nanocrystals (for example, 1 nm to 30 nm), an electron diffraction pattern can be obtained in which multiple spots are observed within a ring-shaped region centered on the direct spot.

[0557] [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 CAAC-OS. Furthermore, the a-like OS has a higher hydrogen concentration in the film than the nc-OS and CAAC-OS.

[0558] <<Oxide semiconductor structure>> Next, the above-mentioned CAC-OS will be described in detail, which relates to the material composition.

[0559] [CAC-OS] CAC-OS is a material structure in which elements constituting a metal oxide are unevenly distributed in a size range of 0.5 nm to 10 nm, preferably 1 nm to 3 nm, or a similar size range. Hereinafter, a metal oxide in which one or more metal elements are unevenly distributed and the regions containing the metal elements are mixed in a size range of 0.5 nm to 10 nm, preferably 1 nm to 3 nm, or a similar size range, is also referred to as a mosaic or patch state.

[0560] Furthermore, CAC-OS has a mosaic structure in which the material is separated into first and second regions, and the first regions are distributed throughout the film (hereinafter also referred to as a cloud structure). That is, CAC-OS is a composite metal oxide having a structure in which the first and second regions are mixed.

[0561] 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.

[0562] 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 rephrased as a region whose main component is In. The second region can be rephrased as a region whose main component is Ga.

[0563] It should be noted that there are cases where a clear boundary between the first region and the second region cannot be observed.

[0564] In addition, CAC-OS in In-Ga-Zn oxide refers to a material structure containing In, Ga, Zn, and O, in which some regions primarily composed of Ga and other regions primarily composed of In are randomly arranged in a mosaic pattern. Therefore, it is presumed that CAC-OS has a structure in which metal elements are distributed nonuniformly.

[0565] The CAC-OS can be formed, for example, by a sputtering method without heating the substrate. When the CAC-OS is formed by a sputtering method, 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 ratio of oxygen gas to the total flow rate of deposition gas during deposition, the better. For example, the flow rate ratio of oxygen gas 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.

[0566] Furthermore, for example, in the case of CAC-OS in an In-Ga-Zn oxide, EDX mapping obtained using EDX (Energy Dispersive X-ray spectroscopy) confirms 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.

[0567] 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 high field-effect mobility (μ).

[0568] 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.

[0569] Therefore, when 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 (the ability to turn on / off). In other words, CAC-OS has a conductive function in part of the material and an insulating function in part of the material, and the material as a whole functions as a semiconductor. By separating the conductive function from the insulating function, both functions can be maximized. Therefore, by using CAC-OS in a transistor, a high on-current (I on ), high field-effect mobility (μ), low leakage current, and good switching behavior can be achieved.

[0570] Furthermore, a transistor using CAC-OS has high reliability, making it ideal for various semiconductor devices such as display devices.

[0571] Oxide semiconductors have a variety of structures, each with 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.

[0572] <Transistors containing oxide semiconductors> Next, a case where the oxide semiconductor is used in a transistor will be described.

[0573] By using the oxide semiconductor for a transistor, a transistor with high field-effect mobility and high reliability can be realized.

[0574] For the transistor, an oxide semiconductor with a low carrier concentration is preferably used. For example, the carrier concentration of the oxide semiconductor is 1×10 17 cm -3 Less than 1 × 10 15 cm -3 or less, more preferably 1 × 10 13 cm -3 Less than or equal to 1×10 11 cm -3 or less, more preferably 1 × 10 10 cm -3 Less than 1 x 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.

[0575] 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.

[0576] Furthermore, charges trapped in the trap states of an oxide semiconductor take a long time to dissipate 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.

[0577] 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.

[0578] <Impurities> Here, the influence of each impurity in an oxide semiconductor will be described.

[0579] When an oxide semiconductor contains silicon or carbon, which is one of the 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 calculated to be 2×10 18 atoms / cm 3 Less than or equal to 2 x 10 17 atoms / cm 3 The following applies.

[0580] Furthermore, when an oxide semiconductor contains an alkali metal or alkaline earth metal, defect levels may be formed and carriers may be generated. Therefore, a transistor using an oxide semiconductor containing an alkali metal or alkaline earth metal is likely to have normally-on characteristics. Therefore, when the concentration of the alkali metal or alkaline earth metal in the oxide semiconductor obtained by SIMS is 1×10 18 atoms / cm 3 Less than or equal to 2 x 10 16 atoms / cm 3 Do the following:

[0581] 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 x 10 18 atoms / cm 3 Less than or equal to 1×10 18 atoms / cm3 Less than 5 × 10, more preferably 17 atoms / cm 3 Do the following:

[0582] 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. When hydrogen enters the oxygen vacancy, electrons serving as carriers may be generated. Furthermore, some of the hydrogen may bond with oxygen bonded to a metal atom to generate electrons serving as carriers. Therefore, a transistor using an oxide semiconductor containing hydrogen is likely to have normally-on characteristics. For this reason, it is preferable to reduce the amount of hydrogen in the oxide semiconductor as much as possible. Specifically, the hydrogen concentration in an oxide semiconductor measured by SIMS is 1×10 20 atoms / cm 3 Less than 1 x 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.

[0583] When an oxide semiconductor with sufficiently reduced impurities is used for a channel formation region of a transistor, stable electrical characteristics can be obtained.

[0584] This embodiment mode can be combined with other embodiment modes as appropriate.

[0585] (Embodiment 7) In this embodiment, electronic devices of one embodiment of the present invention will be described with reference to FIGS.

[0586] 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.

[0587] 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.

[0588] In particular, the display device of one embodiment of the present invention can have high resolution and can therefore be suitably used in electronic devices having a relatively small display area. Examples of such electronic devices include wristwatch-type and bracelet-type information terminals (wearable devices), and head-mounted wearable devices such as VR devices (head-mounted displays), eyeglass-type AR devices, and MR (mixed reality) devices.

[0589] 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, 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. 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.

[0590] 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).

[0591] 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.

[0592] 29A, 29B, 30A, and 30B, an example of a wearable device 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 (Substitutional Reality) or MR 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 sense of immersion for the user.

[0593] Electronic device 700A shown in FIG. 29A and electronic device 700B shown in FIG. 29B 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.

[0594] The display device of one embodiment of the present invention can be applied to the display panel 751. Therefore, the electronic device can display images with extremely high resolution.

[0595] Each of electronic devices 700A and 700B can project an image displayed on display panel 751 onto display area 756 of optical member 753. Because optical member 753 is translucent, the user can see the image displayed in display area 756 superimposed on a transmitted image visually recognized through optical member 753. Therefore, each of electronic devices 700A and 700B is an electronic device capable of AR display.

[0596] 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.

[0597] 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.

[0598] Furthermore, the electronic device 700A and the electronic device 700B are provided with batteries, which can be charged wirelessly and / or by wire.

[0599] 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.

[0600] 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.

[0601] 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. The active layer of the photoelectric conversion device can be made of either or both of an inorganic semiconductor and an organic semiconductor.

[0602] The electronic device 800A shown in FIG. 30A and the electronic device 800B shown in FIG. 30B 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.

[0603] 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 resolution can be provided, which allows a user to feel a high sense of immersion.

[0604] Display unit 820 is provided inside housing 821 at a position that can be viewed through lens 832. Also, by displaying different images on the pair of display units 820, it is possible to perform a three-dimensional display using parallax.

[0605] Electronic device 800A and electronic device 800B can each be said to be electronic devices for VR. A user wearing electronic device 800A or electronic device 800B can view an image displayed on display unit 820 through lens 832.

[0606] 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.

[0607] The user can wear electronic device 800A or electronic device 800B on the head using wearing unit 823. Note that, in Fig. 30A and other figures, a shape similar to the temples of glasses (also called joints or temples) is shown as an example, but the present invention is not limited to this. Wearing unit 823 may be shaped like a helmet or a band, for example, as long as it can be worn by the user.

[0608] 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.

[0609] Although an example having the imaging unit 825 has been 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.

[0610] 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 display unit 820, housing 821, and wearing unit 823. This allows a user to enjoy video and audio simply by wearing electronic device 800A, without the need for separate audio equipment such as headphones, earphones, or speakers.

[0611] 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.

[0612] The electronic device of one embodiment of the present invention may have a function of wireless communication with earphone 750. Earphone 750 has a communication unit (not shown) and has a wireless communication function. Earphone 750 can receive information (e.g., audio data) from the electronic device through the wireless communication function. For example, electronic device 700A shown in FIG. 29A has a function of transmitting information to earphone 750 through the wireless communication function. Furthermore, electronic device 800A shown in FIG. 30A has a function of transmitting information to earphone 750 through the wireless communication function.

[0613] 29B includes 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 wearing unit 723.

[0614] Similarly, electronic device 800B shown in Fig. 30B 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.

[0615] 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.

[0616] As described above, the electronic devices of one embodiment of the present invention are preferably either glasses-type devices (such as the electronic devices 700A and 700B) or goggle-type devices (such as the electronic devices 800A and 800B).

[0617] Furthermore, the electronic device of one embodiment of the present invention can transmit information to the earphone by wire or wirelessly.

[0618] Electronic device 6500 shown in FIG. 31A is a portable information terminal that can be used as a smartphone.

[0619] 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, and a light source 6508. The display portion 6502 has a touch panel function.

[0620] The display device of one embodiment of the present invention can be applied to the display portion 6502.

[0621] FIG. 31B is a schematic cross-sectional view including the end of the housing 6501 on the microphone 6506 side.

[0622] 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.

[0623] 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).

[0624] In an area outside the display unit 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.

[0625] 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.

[0626] 32A shows an example of a television device. A television device 7100 has a display unit 7000 built into a housing 7101. Here, the housing 7101 is supported by a stand 7103.

[0627] The display device of one embodiment of the present invention can be applied to the display portion 7000.

[0628] 32A can be operated using operation switches provided on the housing 7101 and a separate remote control 7111. Alternatively, a touch sensor may be provided in the display unit 7000, and the television 7100 may be operated by touching the display unit 7000 with a finger or the like. The remote control 7111 may have a display unit 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 the video displayed on the display unit 7000 can be controlled.

[0629] The television device 7100 is configured to include a receiver, a modem, and the like. The receiver can receive general television broadcasts. In addition, by connecting to a wired or wireless communication network via the modem, it is possible to perform one-way (from sender to receiver) or two-way (between sender and receiver, or between receivers, etc.) information communication.

[0630] 32B 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. A display portion 7000 is incorporated in the housing 7211.

[0631] The display device of one embodiment of the present invention can be applied to the display portion 7000.

[0632] 32C and 32D show an example of digital signage.

[0633] 32C includes a housing 7301, a display unit 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.

[0634] 32D 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.

[0635] 32C and 32D, the display device of one embodiment of the present invention can be applied to the display portion 7000.

[0636] 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.

[0637] 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, intuitive operation can improve usability.

[0638] 32C and 32D, it is preferable that digital signage 7300 or digital signage 7400 can be linked via wireless communication with information terminal 7311 or information terminal 7411, such as a smartphone carried by a user. For example, advertising information displayed on display unit 7000 can be displayed on the screen of information terminal 7311 or information terminal 7411. Furthermore, by operating information terminal 7311 or information terminal 7411, the display on display unit 7000 can be switched.

[0639] 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.

[0640] The electronic device shown in Figures 33A to 33G 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 the function of measuring 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), a microphone 9008, etc.

[0641] 33A to 33G, the display device of one embodiment of the present invention can be applied to the display portion 9001.

[0642] 33A to 33G 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 pr...

Claims

1. forming a first conductive film over the layer including the transistor; forming a first layer on the first conductive film; forming a first sacrificial layer over the first layer; forming a second sacrificial layer on the first sacrificial layer; forming a resist mask on the second sacrificial layer; removing a portion of the second sacrificial layer using the resist mask to form a third sacrificial layer; removing the resist mask; using the third sacrificial layer to remove a portion of the first sacrificial layer to form a fourth sacrificial layer; removing a portion of the first layer using the third sacrificial layer and the fourth sacrificial layer to form a second layer, a third layer, and a fourth layer; removing a portion of the first conductive film using the third sacrificial layer and the fourth sacrificial layer to form a second conductive film, a third conductive film, and a fourth conductive film; forming a first insulating film on the second conductive film, the third conductive film, the fourth conductive film, the second layer, the third layer, the fourth layer, the third sacrificial layer, and the fourth sacrificial layer; forming a second insulating film on the first insulating film; processing the first insulating film and the second insulating film to form a third insulating film and a fourth insulating film; removing the third sacrificial layer and the fourth sacrificial layer; forming a fifth layer on the third insulating film, the fourth insulating film, the second layer, the third layer, and the fourth layer; forming a fifth conductive layer on the fifth layer; forming a fifth insulating film on the fifth conductive layer; forming a first color conversion layer on the second layer; A method for manufacturing a display device, comprising the step of forming a second color conversion layer over the third layer.

2. In claim 1, the first color conversion layer has a function of converting blue light into red light, the second color conversion layer has a function of converting blue light into green light; A method for manufacturing a display device.

3. In claim 1, the first color conversion layer and the second color conversion layer use a phosphor or a quantum dot; A method for manufacturing a display device.

4. In claim 1, the first color conversion layer and the second color conversion layer are formed by using any one of a droplet discharge method, a coating method, an imprint method, a screen printing method, and an offset printing method; A method for manufacturing a display device.

5. In claim 1, the first color conversion layer and the second color conversion layer use quantum dot films; A method for manufacturing a display device.

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