Display device, and method for manufacturing the display device

Abstract

The present invention provides a highly reliable display device. Provided is a display device comprising a first light emitting element, a second light emitting element adjacent to the first light emitting element, a first insulation layer provided between the first light emitting element and the second light emitting element, a light-shielding layer on the first insulation layer, and a second insulation layer on the light-shielding layer. The first light emitting element has a first pixel electrode, a first EL layer on the first pixel electrode, and a common electrode on the first EL layer, and the second light emitting element has a second pixel electrode, a second EL layer on the second pixel electrode, and a common electrode on the second EL layer. A common electrode is disposed on the second insulation layer.

Description

Display device, display device manufacturing method, display module, and electronic device

[0001] BACKGROUND OF THE INVENTION 1. Field of the Invention One embodiment of the present invention relates to a display device, a manufacturing method of a display device, a display module, and an electronic device.

[0002] Note that one embodiment of the present invention is not limited to the above technical field. Examples of the technical field of one embodiment of the present invention disclosed in this specification and the like include semiconductor devices, display devices, light-emitting devices, power storage devices, memory devices, electronic devices, lighting devices, input devices, input / output devices, driving methods thereof, and manufacturing methods thereof. A semiconductor device refers to any device that can function by utilizing semiconductor characteristics.

[0003] In recent years, there has been a demand for higher definition display panels. Devices requiring high-definition display panels include, for example, smartphones, tablet terminals, and notebook computers. Furthermore, stationary display devices such as televisions and monitors are also required to have higher definitions in line with the trend toward higher resolutions. Furthermore, devices requiring the highest definition include, for example, devices for virtual reality (VR) or augmented reality (AR).

[0004] Furthermore, examples of display devices that can be used for display panels include light-emitting devices that include light-emitting elements such as organic EL (Electro Luminescence) elements or light-emitting diodes (LEDs).

[0005] For example, the basic structure of an organic EL element is a layer containing a light-emitting organic compound sandwiched between a pair of electrodes. By applying a voltage to this element, light can be emitted from the light-emitting organic compound. A display device using such an organic EL element does not require a backlight, which is necessary in, for example, a liquid crystal display device, 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] Patent Document 2 discloses a display device for VR that uses organic EL elements.

[0007] Non-Patent Document 1 discloses a method for fabricating organic optoelectronic devices using standard UV photolithography.

[0008] Patent Document 1: JP 2002-324673 A, International Publication No. 2018 / 087625

[0009] B. Lamprecht et al. , “Organic optoelectronic device fabrication using standard UV photolithography” phys. stat. sol. (RRL) 2, No. 1, p. 16-18 (2008)

[0010] For example, when a light-emitting device, which is a type of display device, is manufactured using UV photolithography, the light-emitting layer may be irradiated with UV (ultraviolet light) and damaged, which may reduce the reliability of the light-emitting element.

[0011] An object of one embodiment of the present invention is to provide a highly reliable display device.An object of one embodiment of the present invention is to provide a display device with high display quality.An object of one embodiment of the present invention is to provide a high-definition display device.An object of one embodiment of the present invention is to provide a display device with a high aperture ratio.An object of one embodiment of the present invention is to provide a display device with low power consumption.

[0012] An object of one embodiment of the present invention is to provide a display device having a novel structure or a manufacturing method of the display device.An object of one embodiment of the present invention is to provide a method for manufacturing the above-described display device with high yield.An object of one embodiment of the present invention is to alleviate at least one of the problems of the prior art.

[0013] Note that the description of these problems does not preclude the existence of other problems. Note that one embodiment of the present invention does not necessarily solve all of these problems. Note that problems other than these can be extracted from the description of the specification, drawings, claims, etc.

[0014] One embodiment of the present invention is a display device including a first light-emitting element, a second light-emitting element adjacent to the first light-emitting element, a first insulating layer provided between the first light-emitting element and the second light-emitting element, a light-shielding layer on the first insulating layer, and a second insulating layer on the light-shielding layer, in which the first light-emitting element has a first pixel electrode, a first EL layer on the first pixel electrode, and a common electrode on the first EL layer, and the second light-emitting element has a second pixel electrode, a second EL layer on the second pixel electrode, and a common electrode on the second EL layer, and the common electrode is disposed on the second insulating layer.

[0015] Alternatively, in the above aspect, the first insulating layer may include an inorganic material, and the second insulating layer may include an organic material.

[0016] Alternatively, in the above aspect, the first insulating layer may include aluminum oxide.

[0017] Alternatively, in the above aspect, the second insulating layer may include an acrylic resin.

[0018] Alternatively, in the above aspect, the first pixel electrode and the second pixel electrode may each have a tapered shape on a side surface in a cross-sectional view of the display device, the first EL layer may cover the side surface of the first pixel electrode, the second EL layer may cover the side surface of the second pixel electrode, the first EL layer may have a first tapered portion between the side surface of the first pixel electrode and the first insulating layer, and the second EL layer may have a second tapered portion between the side surface of the second pixel electrode and the first insulating layer.

[0019] Alternatively, in the above aspect, the taper angle of the first tapered portion and the taper angle of the second tapered portion may each be less than 90°.

[0020] Alternatively, in the above embodiment, the first insulating layer may have a region in contact with the first EL layer and the second EL layer.

[0021] Alternatively, in the above aspect, the first light-emitting element may have a common layer disposed between the first EL layer and the common electrode, the second light-emitting element may have a common layer disposed between the second EL layer and the common electrode, and the common layer may be disposed between the second insulating layer and the common electrode, and the common layer may have at least one 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.

[0022] Another aspect of the present invention is a display module including the display device according to one aspect of the present invention and at least one of a connector and an integrated circuit.

[0023] An electronic device including a display module according to one embodiment of the present invention and at least one of a battery, a camera, a speaker, and a microphone is also one embodiment of the present invention.

[0024] Alternatively, one embodiment of the present invention includes forming a first pixel electrode and a second pixel electrode, forming a first EL film to cover the first pixel electrode and the second pixel electrode, forming a first mask film over the first EL film, and processing the first EL film and the first mask film to form a first EL layer over the first pixel electrode and a first mask layer over the first EL layer, forming a second EL film to cover the first mask layer and the second pixel electrode, forming a second mask film over the second EL film, and processing the second EL film and the second mask film to form a second EL layer over the second pixel electrode and a second EL layer over the second pixel electrode. a second mask layer on the L layer, forming an inorganic insulating film covering the first EL layer, the second EL layer, the first mask layer, and the second mask layer, forming a light-shielding film on the inorganic insulating film, applying a photosensitive organic insulating film on the light-shielding film, irradiating light onto a portion of the organic insulating film to remove a portion of the organic insulating film, forming an organic insulating layer between the first EL layer and the second EL layer, removing a portion of the light-shielding film, forming a light-shielding layer below the organic insulating layer, removing a portion of the inorganic insulating film, forming an inorganic insulating layer below the light-shielding layer, and forming a common electrode on the first EL layer, the second EL layer, and the organic insulating layer.

[0025] Alternatively, in the above aspect, the light may include ultraviolet light.

[0026] Alternatively, in the above aspect, the first pixel electrode and the second pixel electrode may be formed so as to have tapered shapes on their respective side surfaces in a cross-sectional view of the display device, the first EL layer may be formed so as to cover the side surfaces of the first pixel electrode and have a first tapered portion between the side surfaces of the first pixel electrode and the first mask layer, and the second EL layer may be formed so as to cover the side surfaces of the second pixel electrode and have a second tapered portion between the side surfaces of the second pixel electrode and the second mask layer.

[0027] Alternatively, in the above aspect, the first EL layer may be formed so that the taper angle of the first tapered portion is less than 90°, and the second EL layer may be formed so that the taper angle of the second tapered portion is less than 90°.

[0028] Alternatively, in the above embodiment, the first EL layer and the second EL layer may be formed by a photolithography method.

[0029] Alternatively, in the above aspect, there may be a region in which the distance between the first EL layer and the second EL layer is 8 μm or less.

[0030] Alternatively, in the above embodiment, the inorganic insulating film may be formed using an ALD method.

[0031] Alternatively, in the above embodiment, the organic insulating film may be formed using a photosensitive acrylic resin.

[0032] Alternatively, in the above embodiment, the inorganic insulating layer may be formed to have a region in contact with the first EL layer and the second EL layer.

[0033] Alternatively, in the above embodiment, after forming the inorganic insulating layer and before forming the common electrode, a common layer having at least one 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 may be formed, and the common electrode may be formed on the common layer.

[0034] According to one embodiment of the present invention, a highly reliable display device can be provided. Furthermore, a display device with high display quality can be provided. Furthermore, a high-definition display device can be provided. Furthermore, a display device with a high aperture ratio can be provided. Furthermore, a display device with low power consumption can be provided.

[0035] According to one embodiment of the present invention, a display device having a novel structure or a manufacturing method of the display device can be provided. Also, a method for manufacturing the above-described display device with high yield can be provided. According to one embodiment of the present invention, at least one of the problems of the prior art can be alleviated.

[0036] Note that the description of these effects does not preclude the existence of other effects. Note that one embodiment of the present invention does not necessarily have all of these effects. Note that effects other than these can be extracted from the description in the specification, drawings, claims, etc.

[0037] FIG. 1 is a top view showing an example of a display device. FIGS. 2A, 2B1, and 2B2 are cross-sectional views showing an example of a display device. FIGS. 3A and 3B are cross-sectional views showing an example of a display device. FIGS. 4A, 4B1, and 4B2 are cross-sectional views showing an example of a display device. FIGS. 5A and 5B are cross-sectional views showing an example of a display device. FIGS. 6A and 6B are cross-sectional views showing an example of a display device. FIGS. 7A and 7B are cross-sectional views showing an example of a display device. FIGS. 8A to 8C are cross-sectional views showing an example of a manufacturing method of a display device. FIGS. 9A to 9C are cross-sectional views showing an example of a manufacturing method of a display device. FIGS. 10A to 10C are cross-sectional views showing an example of a manufacturing method of a display device. FIGS. 11A to 11C are cross-sectional views showing an example of a manufacturing method of a display device. FIGS. 12A to 12C are cross-sectional views showing an example of a manufacturing method of a display device. FIGS. 13A and 13B are cross-sectional views showing an example of a manufacturing method of a display device. FIGS. 14A and 14B are cross-sectional views showing an example of a manufacturing method of a display device. FIGS. 15A and 15B are cross-sectional views illustrating an example of a method for manufacturing a display device. FIGS. 16A to 16C are cross-sectional views illustrating an example of a method for manufacturing a display device. FIGS. 17A and 17B are cross-sectional views illustrating an example of a method for manufacturing a display device. FIGS. 18A to 18F are diagrams illustrating an example of a pixel. FIGS. 19A and 19B are diagrams illustrating an example of a display device. FIG. 20 is a diagram illustrating an example of a display device. FIG. 21 is a diagram illustrating an example of a display device. FIG. 22 is a diagram illustrating an example of a display device. FIG. 23 is a diagram illustrating an example of a display device. FIG. 24 is a diagram illustrating an example of a display device. FIG. 25 is a diagram illustrating an example of a display device. FIG. 26 is a diagram illustrating an example of a display device. FIGS. 27A and 27B are diagrams illustrating an example of a display device. FIGS. 28A to 28F are diagrams illustrating an example of a light-emitting element. FIGS. 29A to 29D are diagrams illustrating an example of an electronic device. FIGS. 30A to 30F are diagrams illustrating an example of an electronic device. FIGS. 31A to 31G are diagrams illustrating an example of an electronic device.

[0038] Hereinafter, embodiments will be described with reference to the drawings. However, it will be readily understood by those skilled in the art that the embodiments can be implemented in many different ways and that various changes in form and details can be made without departing from the spirit and scope of the present invention. Therefore, the present invention should not be interpreted as being limited to the following description of the embodiments.

[0039] In the configuration of the invention described below, the same parts or parts having similar functions are denoted by the same reference numerals in different drawings, and repeated explanations thereof will be omitted. In addition, when referring to similar functions, the same hatch pattern may be used and no particular reference numeral may be assigned.

[0040] In the drawings described in this specification, the size of each component, the thickness of a layer, or an area may be exaggerated for clarity, and therefore, the drawings are not necessarily limited to the scale.

[0041] In this specification, ordinal numbers such as "first" and "second" are used to avoid confusion of components and do not limit the number.

[0042] In addition, in this specification and the like, a display device may be read as an electronic device.

[0043] In this specification and the like, a display panel, which is one aspect of a display device, has a function of displaying (outputting) an image on a display surface, and therefore, the display panel is one aspect of an output device.

[0044] Furthermore, in this specification etc., a display panel having a connector such as an FPC (Flexible Printed Circuit) or a TCP (Tape Carrier Package) attached to its substrate, or a display panel having an IC mounted on its substrate by a COG (Chip On Glass) method or the like, may be referred to as a display panel module, a display module, or simply a display panel, etc. Furthermore, in this specification etc., a display panel module, a display module, or a display panel may be referred to as a display device.

[0045] Furthermore, in this specification and the like, the terms "film" and "layer" can be interchangeable in some cases or depending on the situation. For example, the terms "conductive layer" and "insulating layer" can sometimes be interchangeable with the terms "conductive film" and "insulating film."

[0046] In addition, in this specification and the like, the terms "end" and "side" may be interchangeable in some cases. For example, when the term "end" refers to a side end, "end" may be replaced with "side."

[0047] In this specification and the like, the EL layer refers to a layer provided between a pair of electrodes of a light-emitting element and containing at least a light-emitting substance (also referred to as a light-emitting layer), or a stack including a light-emitting layer.

[0048] In this specification and the like, the term "element" may be replaced with the term "device." For example, a "light-emitting element" may be replaced with a "light-emitting device."

[0049] In this specification etc., a device fabricated using a metal mask or an FMM (fine metal mask, high-resolution metal mask) may be referred to as a device with an MM (metal mask) structure. Also, in this specification etc., a device fabricated without using a metal mask or an FMM may be referred to as a device with an MML (metal maskless) structure.

[0050] In this specification and the like, holes or electrons may be referred to as "carriers." Specifically, a hole injection layer or an electron injection layer may be referred to as a "carrier injection layer," a hole transport layer or an electron transport layer may be referred to as a "carrier transport layer," and a hole block layer or an electron block layer may be referred to as a "carrier block layer." Note that the above-mentioned carrier injection layer, carrier transport layer, and carrier block layer may not be clearly distinguishable from each other depending on their cross-sectional shapes, properties, etc. Furthermore, one layer may have two or three functions among the carrier injection layer, carrier transport layer, and carrier block layer.

[0051] Embodiment 1 In this embodiment, a display device according to one embodiment of the present invention will be described.

[0052] One embodiment of the present invention is a display device having a display portion capable of full-color display. The display portion includes a first subpixel and a second subpixel that emit light of different colors. The first subpixel has a first light-emitting element that emits blue light, and the second subpixel has a second light-emitting element that emits light of a color different from that of the first light-emitting element. The first light-emitting element and the second light-emitting element each contain at least one material different from each other, for example, different light-emitting substances from each other. That is, a display device according to one embodiment of the present invention uses light-emitting elements that are fabricated for each light-emitting color.

[0053] A structure in which different light-emitting layers are created for each color light-emitting element (e.g., blue (B), green (G), and red (R)), or in which different light-emitting layers are painted, is sometimes called an SBS (Side By Side) structure. The SBS structure allows the materials and configuration to be optimized for each light-emitting element, increasing the freedom in selecting materials and configurations and making it easier to improve brightness and reliability. Furthermore, a light-emitting element that can emit white light is sometimes called a white light-emitting element. Note that by combining a white light-emitting element with a colored layer (e.g., a color filter), a display device that displays full color can be provided.

[0054] When manufacturing a display device having a plurality of light-emitting elements each emitting a different light color, it is necessary to form each of the light-emitting layers emitting different light colors in an island shape. In this specification, the term "island shape" refers to a state in which two or more layers formed using the same material in the same process are physically separated. For example, an island-shaped light-emitting layer refers to a state in which the light-emitting layer is physically separated from an adjacent light-emitting layer.

[0055] 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 a high aperture ratio. Furthermore, during deposition, the contours of the layer can become blurred, resulting in a thin edge. In other words, the thickness of the island-shaped light-emitting layer can vary depending on the location. Furthermore, when producing 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.

[0056] In a manufacturing method of a display device according to one embodiment of the present invention, a first EL film including a light-emitting film emitting light of a first color is formed over the entire surface, and then a mask film is formed on the first EL film. A resist mask is then formed on the mask film, and the mask film is processed using the resist mask. In this manner, a first mask layer can be formed. Next, the first EL film is processed using the first mask layer as a hard mask. This allows the first EL layer including a light-emitting layer emitting light of the first color to be formed in an island shape. After that, a second EL film including a light-emitting film emitting light of a second color is formed over the entire surface, and then the second EL film is processed in a manner similar to that used for processing the first EL film, thereby forming the second EL layer including a light-emitting layer emitting light of the second color in an island shape. Note that a second mask layer is formed on the second EL layer. The mask film and the mask layer serve to protect the EL layer during the manufacturing process of the display device.

[0057] In this specification and the like, processing a film to form a layer refers to, for example, removing a portion of the film. For example, a layer can be formed by patterning a film. Removing a portion of a layer may also be referred to as processing a layer.

[0058] In this specification and the like, the mask layer may be referred to as a sacrificial layer, and the mask film may be referred to as a sacrificial film.

[0059] When the light-emitting film is processed into an island shape, a structure in which the light-emitting film is processed using photolithography directly above the light-emitting film is conceivable. In such a structure, the light-emitting film may be damaged (e.g., damaged by processing), which may significantly impair reliability. Therefore, when manufacturing a display device according to one embodiment of the present invention, it is preferable to use a method in which a mask film is formed on a layer (e.g., a carrier transport layer or a carrier injection layer, more specifically, an electron transport layer or an electron injection layer) located above the light-emitting film and the light-emitting film is processed into an island shape. By applying this method, a highly reliable display device can be provided.

[0060] As described above, the island-shaped EL layer manufactured by the method for manufacturing a display device according to one embodiment of the present invention is not formed using a metal mask having a fine pattern, but is formed by forming an EL film over the entire surface and then processing it. Therefore, a high-definition display device or a display device with a high aperture ratio, which has been difficult to achieve until now, can be realized. Furthermore, since the EL layer can be separately manufactured for each color, a display device with extremely vivid, high contrast, and high display quality can be realized. Furthermore, by providing a mask film on the EL film, damage to the EL film during the manufacturing process of the display device can be reduced, thereby improving the reliability of the light-emitting element.

[0061] While it is difficult to achieve a distance of less than 10 μm between adjacent light-emitting elements using, for example, a metal mask, the above-described method can reduce the distance to less than 10 μm, 8 μm or less, 5 μm or less, 3 μm or less, 2 μm or less, or even 1 μm or less. Furthermore, by using an exposure device for LSIs, for example, the distance between adjacent light-emitting elements can be reduced 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 elements, 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, and even less than 100%.

[0062] 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 form 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 a light-emitting region relative to the overall area of ​​the pattern. On the other hand, the above-described manufacturing method processes a film formed to a uniform thickness, allowing island-shaped EL layers to be formed with a uniform thickness. Therefore, even with a fine pattern, almost the entire area can be used as a light-emitting region. This allows the manufacture of a display device that combines high definition and a high aperture ratio.

[0063] In a manufacturing method of a display device according to one embodiment of the present invention, it is preferable to form an EL film over the entire surface and then form a mask film over the EL film, and then form a resist mask over the mask film and process the EL film and the mask film using the resist mask to form an island-shaped EL layer.

[0064] By providing the mask film over the EL film, damage to the EL layer during the manufacturing process of the display device can be reduced, and the reliability of the light-emitting element can be improved.

[0065] Here, the first EL layer and the second EL layer each include at least a light-emitting layer and preferably consist of multiple layers. Specifically, it is preferable to have one or more layers on the light-emitting layer. By having another layer between the light-emitting layer and the mask layer, it is possible to prevent the light-emitting layer from being exposed to the outermost surface during the manufacturing process of the display device, thereby reducing damage to the light-emitting layer. This can improve the reliability of the light-emitting element. Therefore, it is preferable that the first EL layer and the second EL layer each include a light-emitting layer and a carrier transport layer (electron transport layer or hole transport layer) on the light-emitting layer.

[0066] In light-emitting elements that emit different colors, it is not necessary to form all layers constituting the EL layer separately; some layers can be formed in the same process. Examples of layers included in the EL layer include a light-emitting layer, a carrier injection layer (hole injection layer and electron injection layer), a carrier transport layer (hole transport layer and electron transport layer), and a carrier block layer (hole block layer and electron block layer). In a manufacturing method of a display device according to one embodiment of the present invention, some layers constituting the EL layer are formed in an island shape for each color, and then at least a portion of the mask layer is removed. The remaining layers constituting the EL layer (sometimes referred to as common layers) and a common electrode (also referred to as an upper electrode) are formed in common (as a single film) for each color. For example, a carrier injection layer and a common electrode can be formed in common for each color.

[0067] On the other hand, the carrier injection layer is often a layer with relatively high conductivity among the EL layers. Therefore, when the carrier injection layer comes into contact with the side surface of a part of the EL layer formed in an island shape or with the side surface of the pixel electrode, there is a risk of short-circuiting the light-emitting element. Even when the carrier injection layer is provided in an island shape and a common electrode is formed in common for each color, there is a risk of short-circuiting the light-emitting element when the common electrode comes into contact with the side surface of the EL layer or the side surface of the pixel electrode.

[0068] Therefore, a display device according to one embodiment of the present invention includes an insulating layer that covers at least the side surface of the island-shaped light-emitting layer. The insulating layer may also cover a part of the top surface of the island-shaped light-emitting layer. The side surface of the island-shaped light-emitting layer here refers to a surface of the interface between the island-shaped light-emitting layer and another layer that is not parallel to the substrate (or the surface on which the light-emitting layer is formed).

[0069] This prevents at least a portion of the island-shaped EL layer and the pixel electrode from coming into contact with the carrier injection layer or the common electrode, thereby preventing short circuits in the light-emitting element and improving the reliability of the light-emitting element.

[0070] The insulating layer preferably functions as a barrier insulating layer against at least one of water and oxygen, suppresses diffusion of at least one of water and oxygen, and captures or fixes (also referred to as gettering) at least one of water and oxygen.

[0071] Note that in this specification and the like, a barrier insulating layer refers to an insulating layer 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.

[0072] By using an insulating layer having a function as a barrier insulating layer or a gettering function, it is possible to suppress the intrusion of impurities (typically, at least one of water and oxygen) that may diffuse into each light-emitting element from the outside. With this structure, it is possible to provide a highly reliable light-emitting element and further a highly reliable display device.

[0073] A display device of one embodiment of the present invention includes a pixel electrode functioning as an anode; a hole injection layer, a hole transport layer, a light-emitting layer, and an electron transport layer, each of which has an island shape and is provided in this order over the pixel electrode; insulating layers provided so as to cover side surfaces of the hole injection layer, the hole transport layer, the light-emitting layer, and the electron transport layer; an electron injection layer provided over the electron transport layer; and a common electrode provided over the electron injection layer and functioning as a cathode.

[0074] 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 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.

[0075] Among EL layers, the hole injection layer, the electron injection layer, or the like is often a layer 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 the layers from contacting, for example, a common electrode. Therefore, short circuits of the light-emitting element can be prevented, and the reliability of the light-emitting element can be improved.

[0076] The insulating layer covering the side surfaces of the island-shaped EL layer can have a stacked structure of a first insulating layer (also called an inorganic insulating layer) made of an inorganic material and a second insulating layer (also called an organic insulating layer) made of an organic material. The first insulating layer can be provided so as to be in contact with the EL layer. The second insulating layer can be provided so as to planarize the recesses provided in the first insulating layer.

[0077] The first insulating layer and the second insulating layer can be formed, for example, by forming the first EL layer and the second EL layer, and then forming and processing a first insulating film (also called an inorganic insulating film) and a second insulating film (also called an organic insulating film). Here, if a photosensitive organic insulating film is used as the second insulating film, the second insulating film can be processed through exposure and development processes to form the second insulating layer. Therefore, the second insulating film can be processed without using, for example, dry etching, thereby reducing damage to the EL layer.

[0078] When a photosensitive organic insulating film is used as the second insulating film, the second insulating film may be irradiated with ultraviolet light in the exposure step, which may result in the EL layer being irradiated with ultraviolet light and damaging the EL layer.

[0079] Therefore, in one embodiment of the present invention, a light-shielding film is provided between the first insulating film and the second insulating film. This can prevent the EL layer from being damaged by ultraviolet light even when a photosensitive organic insulating film is used as the second insulating film and ultraviolet light is irradiated in an exposure process. Therefore, the display device of one embodiment of the present invention can be a highly reliable display device.

[0080] In one embodiment of the present invention, the second insulating film is processed to form a second insulating layer, and then the light-shielding film is processed to form a light-shielding layer. Subsequently, the first insulating film is processed to form a first insulating layer. After that, a common layer and a common electrode are formed, thereby completing the display device of one embodiment of the present invention. Note that providing a light-shielding layer on the first insulating layer, which can be an inorganic insulating layer, can prevent the light-shielding layer from contacting the EL layer. Therefore, providing the first insulating layer can broaden the range of materials that can be used for the light-shielding layer. For example, a material that may damage the EL layer when in contact with the EL layer can be used for the light-shielding layer. Furthermore, a method that may damage the EL layer if the EL layer is exposed during the formation of the light-shielding layer can be used for forming the light-shielding layer.

[0081] In the display device of one embodiment of the present invention, the EL layer can be provided to cover the side surface of the pixel electrode. Here, when the side surface of the pixel electrode has a tapered shape in a cross-sectional view of the display device, the EL layer is also formed to have a tapered shape. Specifically, the EL layer is formed to have a tapered portion between the side surface of the pixel electrode and the first insulating layer. Therefore, the tapered side surface of the pixel electrode is preferable because coverage of the EL layer with respect to the pixel electrode can be improved. Furthermore, the tapered side surface of the pixel electrode is preferable because foreign matter (e.g., dust or particles) can be suitably removed by, for example, cleaning during a manufacturing process of the display device of one embodiment of the present invention.

[0082] On the other hand, when the EL layer is formed to have a tapered portion, the tapered portion is more likely to be irradiated with ultraviolet light during an exposure process of the second insulating film, which can be a photosensitive organic insulating film, compared to when the EL layer is formed so that the tapered portion is vertical in a cross-sectional view of the display device. Therefore, by providing a light-shielding film between the first insulating film and the second insulating film as described above, the tapered portion of the EL layer can be prevented from being irradiated with ultraviolet light, thereby suppressing damage to the EL layer. As described above, the display device of one embodiment of the present invention can improve coverage of the EL layer with respect to the pixel electrode and suppress damage to the EL layer during the manufacturing process. Therefore, the display device of one embodiment of the present invention can be a highly reliable display device.

[0083] In the display device of one embodiment of the present invention, an insulating layer covering an edge of the pixel electrode is not required between the pixel electrode and the EL layer. Therefore, the distance between adjacent light-emitting elements can be significantly shortened. Therefore, the display device can have higher definition or higher resolution. Furthermore, a mask for forming the insulating layer is not required, which reduces the manufacturing cost of the display device.

[0084] Furthermore, by using a structure in which an insulating layer covering an edge of the pixel electrode is not provided between the pixel electrode and the EL layer, in other words, by using a structure in which an insulating layer is not provided between the pixel electrode and the EL layer, light from the EL layer can be efficiently extracted. Therefore, the display device of one embodiment of the present invention can have extremely low viewing angle dependence. By reducing the viewing angle dependence, the visibility of images in the display device can be improved. For example, in the display device of one embodiment of the present invention, the viewing angle (the maximum angle at which a certain contrast ratio is maintained when the screen is viewed from an oblique direction) can be set to a range of 100° to less than 180°, preferably 150° to 170°. Note that the above viewing angle can be applied to both the vertical and horizontal directions.

[0085] [Configuration Example 1 of Display Device] Fig. 1 shows a top view of a display device 100. The display device 100 has a display section in which a plurality of pixels 103 are arranged, and a connection section 140 on the outside of the display section. A plurality of sub-pixels are arranged in a matrix in the display section. Fig. 1 shows two rows and six columns of sub-pixels, which together form a two-row, two-column pixel. The connection section 140 can also be called a cathode contact section.

[0086] A stripe arrangement is applied to the pixel 103 shown in FIG. 1 . The pixel 103 shown in FIG. 1 is composed of three subpixels: subpixel 110a, subpixel 110b, and subpixel 110c. The subpixels 110a, 110b, and 110c each have a light-emitting element that emits light of a different color. Examples of the subpixels 110a, 110b, and 110c include subpixels of three colors: red (R), green (G), and blue (B), and subpixels of three colors: yellow (Y), cyan (C), and magenta (M). The number of types of subpixels is not limited to three, and may be four or more. Examples of the four subpixels include subpixels of four colors: R, G, B, and white (W), subpixels of four colors: R, G, B, and Y, and subpixels of R, G, B, and infrared (IR).

[0087] In this specification, the row direction may be referred to as the X direction, and the column direction may be referred to as the Y direction. The X direction and the Y direction intersect, for example, perpendicularly (see FIG. 1).

[0088] FIG. 1 shows an example in which sub-pixels of different colors are arranged side by side in the X direction, and sub-pixels of the same color are arranged side by side in the Y direction.

[0089] 1 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. The top surface shape of the connection unit 140 may be strip-shaped, L-shaped, U-shaped, frame-shaped, or the like. Furthermore, the connection unit 140 may be singular or plural.

[0090] 2A shows a cross-sectional view taken along dashed line X1-X2 in FIG. 1. As shown in FIG. 2A, in the display device 100, an insulating layer is provided on a layer 101 including transistors, and light-emitting elements 130a, 130b, and 130c are provided on the insulating layer, with a protective layer 131 provided to cover these light-emitting elements. A substrate 120 is bonded to the protective layer 131 by an adhesive layer 122. Furthermore, an insulating layer 125, a light-shielding layer 135 on the insulating layer 125, and an insulating layer 127 on the light-shielding layer 135 are provided between adjacent light-emitting elements 130.

[0091] In this specification and the like, when describing matters common to, for example, the light-emitting elements 130a, 130b, and 130c, they may be referred to as the light-emitting elements 130. When describing matters common to other components distinguished by alphabets, they may also be described using symbols without the alphabets.

[0092] 2A shows multiple cross sections of insulating layer 125, multiple cross sections of light-shielding layer 135, and multiple cross sections of insulating layer 127, but when display device 100 is viewed from above, insulating layer 125, light-shielding layer 135, and insulating layer 127 are each connected to one another. In other words, display device 100 can be configured to have, for example, one insulating layer 125, one light-shielding layer 135, and one insulating layer 127. Note that display device 100 may have multiple insulating layers 125 and light-shielding layers 135 that are separated from one another, or may have multiple insulating layers 127 that are separated from one another.

[0093] 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 element is formed, a bottom emission type that emits light toward a substrate on which a light-emitting element is formed, and a dual emission type that emits light to both sides.

[0094] The layer 101 including the transistor may have, for example, a stacked structure in which a plurality of transistors are provided on a substrate and an insulating layer is provided to cover these transistors. The insulating layer over the transistor may have a single-layer structure or a stacked structure. For example, FIG. 2A shows insulating layers over the transistor, including an insulating layer 255a, an insulating layer 255b over the insulating layer 255a, and an insulating layer 255c over the insulating layer 255b. These insulating layers may have recesses between adjacent light-emitting elements 130. For example, FIG. 2A shows an example in which a recess is provided in the insulating layer 255c.

[0095] The insulating layers 255a, 255b, and 255c can be formed using various inorganic insulating films such as an oxide insulating film, a nitride insulating film, an oxynitride insulating film, and a nitride oxide insulating film. The insulating layers 255a and 255c are preferably formed using an oxide insulating film or an oxynitride insulating film such as a silicon oxide film, a silicon oxynitride film, or an aluminum oxide film. The insulating layer 255b is preferably formed using a nitride insulating film or a nitride oxide insulating film such as a silicon nitride film or a silicon nitride oxide film. More specifically, the insulating layers 255a and 255c are preferably formed using silicon oxide films, and the insulating layer 255b is preferably formed using a silicon nitride film. The insulating layer 255b preferably has a function as an etching protective film.

[0096] In this specification and the like, 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.

[0097] The light-emitting elements 130a, 130b, and 130c each emit light of a different color. Preferably, the light-emitting elements 130a, 130b, and 130c are combined to emit light of three colors, for example, red (R), green (G), and blue (B).

[0098] As the light-emitting elements 130a, 130b, and 130c, it is preferable to use EL elements such as organic light-emitting diodes (OLEDs) or quantum-dot light-emitting diodes (QLEDs). Examples of light-emitting materials included in the EL elements include fluorescent materials, phosphorescent materials, inorganic compounds (e.g., quantum dot materials), and thermally activated delayed fluorescence (TADF materials). Note that, as the TADF material, a material in thermal equilibrium between a singlet excited state and a triplet excited state may be used. Such TADF materials have a short emission lifetime (excitation lifetime), which can suppress a decrease in the emission efficiency of the light-emitting elements in the high-brightness region.

[0099] The light-emitting element has an EL layer between a pair of electrodes. The EL layer has at least a light-emitting layer. 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.

[0100] One of a pair of electrodes of a light-emitting element functions as an anode and the other functions as a cathode. In the following, a case where the pixel electrode functions as the anode and the common electrode functions as the cathode will be described as an example.

[0101] It is preferable that the side surfaces of the pixel electrode 111a, the pixel electrode 111b, and the pixel electrode 111c have a tapered shape because it is easy to remove foreign matter (also called dust or particles) during the manufacturing process of the display device by, for example, cleaning.

[0102] The light-emitting element 130a has a pixel electrode 111a on the insulating layer 255c, an EL layer 113a on the pixel electrode 111a, a common layer 114 on the EL layer 113a, and a common electrode 115 on the common layer 114. The EL layer 113a and the common layer 114 can also be collectively referred to as an EL layer.

[0103] The light-emitting element 130b has a pixel electrode 111b on the insulating layer 255c, an EL layer 113b on the pixel electrode 111b, a common layer 114 on the EL layer 113b, and a common electrode 115 on the common layer 114. The EL layer 113b and the common layer 114 can also be collectively referred to as an EL layer.

[0104] The light-emitting element 130c has a pixel electrode 111c on an insulating layer 255c, an EL layer 113c on the pixel electrode 111c, a common layer 114 on the EL layer 113c, and a common electrode 115 on the common layer 114. The EL layer 113c and the common layer 114 can also be collectively referred to as an EL layer.

[0105] The EL layer 113a, the EL layer 113b, and the EL layer 113c can each be provided in an island shape. On the other hand, the common layer 114 and the common electrode 115 can be shared by a plurality of light-emitting elements .

[0106] The structure of the light emitting element of this embodiment is not particularly limited, and may be a single structure or a tandem structure.

[0107] The EL layer 113a, the EL layer 113b, and the EL layer 113c each include at least a light-emitting layer. For example, it is preferable that the EL layer 113a includes a light-emitting layer that emits red light, the EL layer 113b includes a light-emitting layer that emits green light, and the EL layer 113c includes a light-emitting layer that emits blue light.

[0108] Furthermore, the EL layer 113a, the EL layer 113b, and the EL layer 113c may each have one or more of a hole injection layer, a hole transport layer, a hole blocking layer, a charge generation layer, an electron blocking layer, an electron transport layer, and an electron injection layer.

[0109] For example, the EL layer 113a, the EL layer 113b, and the EL layer 113c may each include a hole injection layer, a hole transport layer, a light-emitting layer, and an electron transport layer. Alternatively, an electron blocking layer may be provided between the hole transport layer and the light-emitting layer. Alternatively, an electron injection layer may be provided on the electron transport layer.

[0110] For example, the EL layer 113a, the EL layer 113b, and the EL layer 113c may each include an electron injection layer, an electron transport layer, a light-emitting layer, and a hole transport layer in this order. Alternatively, a hole blocking layer may be provided between the electron transport layer and the light-emitting layer. Alternatively, a hole injection layer may be provided on the hole transport layer.

[0111] The EL layer 113a, the EL layer 113b, and the EL layer 113c preferably include a light-emitting layer and a carrier transport layer (electron transport layer or hole transport layer) on the light-emitting layer. Since the surfaces of the EL layer 113a, the EL layer 113b, and the EL layer 113c are exposed during the manufacturing process of the display device, providing the carrier transport layer on the light-emitting layer can prevent the light-emitting layer from being exposed to the outermost surface and reduce damage to the light-emitting layer. This can improve the reliability of the light-emitting element 130.

[0112] The EL layer 113a, the EL layer 113b, and the EL layer 113c may each include, for example, a first light-emitting unit, a charge generation layer, and a second light-emitting unit. For example, it is preferable that the EL layer 113a has two or more light-emitting units that emit red light, the EL layer 113b has two or more light-emitting units that emit green light, and the EL layer 113c has two or more light-emitting units that emit blue light.

[0113] The second light-emitting unit preferably includes a light-emitting layer and a carrier transport layer (electron transport layer or hole transport layer) on the light-emitting layer. Since the surface of the second light-emitting unit is exposed during the manufacturing process of the display device, providing the carrier transport layer on the light-emitting layer can prevent the light-emitting layer from being exposed on the outermost surface and reduce damage to the light-emitting layer. This can improve the reliability of the light-emitting element 130.

[0114] The EL layers 113a, 113b, and 113c can have different thicknesses. Specifically, the thicknesses can be set to provide optical path lengths that intensify the light emitted from the EL layers 113a to 113c. This realizes a micro-optical resonator (microcavity) structure, and can improve the color purity of the light-emitting elements 130a, 130b, and 130c.

[0115] The common layer 114 includes, for example, an electron injection layer or a hole injection layer. Alternatively, the common layer 114 may include a stack of an electron transport layer and an electron injection layer, or a stack of a hole transport layer and a hole injection layer. As described above, the common layer 114 is shared by the light-emitting element 130 a, the light-emitting element 130 b, and the light-emitting element 130 c.

[0116] In a display device according to one embodiment of the present invention, the distance between light-emitting elements can be reduced. Specifically, the distance between light-emitting elements, the distance between EL layers, or the distance between pixel electrodes can be set to less than 10 μm, 8 μm or less, 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 display device according to one embodiment of the present invention has a region where the distance between two adjacent island-shaped EL layers is 1 μm or less, preferably 0.5 μm (500 nm) or less, and more preferably 100 nm or less.

[0117] A protective layer 131 is preferably provided over the light-emitting elements 130a, 130b, and 130c. Providing the protective layer 131 can improve the reliability of the light-emitting element 130. The protective layer 131 may have a single-layer structure or a stacked structure of two or more layers.

[0118] There is no restriction on the conductivity of the protective layer 131. The protective layer 131 can be made of at least one of an insulating film, a semiconductor film, and a conductive film.

[0119] The protective layer 131 has an inorganic film, which can prevent oxidation of the common electrode 115 and prevent impurities (water, oxygen, etc.) from entering the light-emitting element, thereby suppressing deterioration of the light-emitting element and improving the reliability of the display device.

[0120] The protective layer 131 can be formed using, 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 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, the protective layer 131 preferably includes a nitride insulating film or a nitride oxide insulating film, and more preferably includes a nitride insulating film.

[0121] Alternatively, an inorganic film containing In—Sn oxide (also referred to as ITO), In—Zn oxide, Ga—Zn oxide, Al—Zn oxide, indium gallium zinc oxide (In—Ga—Zn oxide, also referred to as IGZO), or the like can be used for the protective layer 131. The inorganic film preferably has high resistance, specifically, preferably has higher resistance than the common electrode 115. The inorganic film may further contain nitrogen.

[0122] When light emitted from the light-emitting element 130 is extracted through the protective layer 131, it is preferable that the protective layer 131 has high transparency to visible light. For example, ITO, IGZO, and aluminum oxide are preferable because they are inorganic materials that have high transparency to visible light.

[0123] For example, a stacked structure of an aluminum oxide film and a silicon nitride film on the aluminum oxide film, or a stacked structure of an aluminum oxide film and an IGZO film on the aluminum oxide film can be used as the protective layer 131. By using such a stacked structure, impurities (water, oxygen, etc.) can be prevented from entering the EL layer side.

[0124] Furthermore, the protective layer 131 may have an organic film. For example, the protective layer 131 may have both an organic film and an inorganic film. Examples of organic materials that can be used for the protective layer 131 include the organic insulating materials that can be used for the insulating layer 127 described below.

[0125] The protective layer 131 may have a two-layer structure formed using different film formation methods. Specifically, the first layer of the protective layer 131 may be formed using an atomic layer deposition (ALD) method, and the second layer of the protective layer 131 may be formed using a sputtering method.

[0126] 2A, for example, between the pixel electrode 111a and the EL layer 113a, there is no insulating layer covering the upper end of the pixel electrode 111a. Furthermore, between the pixel electrode 111b and the EL layer 113b, there is no insulating layer covering the upper end of the pixel electrode 111b. Furthermore, between the pixel electrode 111c and the EL layer 113c, there is no insulating layer covering the upper end of the pixel electrode 111c. This allows the distance between adjacent light-emitting elements 130 to be extremely short. This allows for a high-definition or high-resolution display device.

[0127] 2A , for example, a mask layer 118a is located over the EL layer 113a of the light-emitting element 130a, a mask layer 118b is located over the EL layer 113b of the light-emitting element 130b, and a mask layer 118c is located over the EL layer 113c of the light-emitting element 130c. As will be described in detail later, the mask layer 118a is a mask layer that can be used as a hard mask for processing an EL film to form the island-shaped EL layer 113a, with a portion remaining. Similarly, the mask layer 118b is a mask layer that was provided during the formation of the EL layer 113b, and the mask layer 118c is a mask layer that was provided during the formation of the EL layer 113c, with a portion remaining. In this manner, the display device of one embodiment of the present invention may have a mask layer used to protect the EL layer during its manufacture that is partially remaining. The same material may be used for any two or all of the mask layers 118a to 118c, or different materials may be used for each of the mask layers 118a to 118c.

[0128] 2A , one end of the mask layer 118a is aligned or approximately aligned with the end of the EL layer 113a, and the other end of the mask layer 118a is located on the EL layer 113a. Here, it is preferable that the other end of the mask layer 118a overlaps the EL layer 113a and the pixel electrode 111a. In this case, the other end of the mask layer 118a is easily formed on a substantially flat surface of the EL layer 113a. The same applies to the mask layers 118b and 118c. Furthermore, the mask layer 118 remains, for example, between the EL layer 113, which has been processed into an island shape, and the insulating layer 125.

[0129] For example, one or more of a metal film, an alloy film, a metal oxide film, a semiconductor film, an organic insulating film, an inorganic insulating film, etc. can be used as the mask layer 118. Various inorganic insulating films that can be used for the protective layer 131 can be used as the mask layer. For example, inorganic insulating materials such as aluminum oxide, hafnium oxide, or silicon oxide can be used.

[0130] 2A , the insulating layer 125, the light-shielding layer 135, and the insulating layer 127 preferably cover a portion of the top surface of the island-shaped EL layer 113. By covering not only the side surfaces but also the top surface of the island-shaped EL layer 113 with the insulating layer 125, the light-shielding layer 135, and the insulating layer 127, peeling of the EL layer 113 can be more effectively prevented, thereby improving the reliability of the light-emitting element 130. Furthermore, the manufacturing yield of the light-emitting element 130 can be further improved. FIG. 2A shows an example in which a stacked structure of the EL layer 113a, the mask layer 118a, the insulating layer 125, the light-shielding layer 135, and the insulating layer 127 is located on the edge of the pixel electrode 111a. Similarly, a layered structure of an EL layer 113b, a mask layer 118b, an insulating layer 125, a light-shielding layer 135, and an insulating layer 127 is located on the end of the pixel electrode 111b, and a layered structure of an EL layer 113c, a mask layer 118c, an insulating layer 125, a light-shielding layer 135, and an insulating layer 127 is located on the end of the pixel electrode 111c.

[0131] For example, Figure 2A shows an example in which the end of the EL layer 113a is located outside the end of the pixel electrode 111a, the end of the EL layer 113b is located outside the end of the pixel electrode 111b, and the end of the EL layer 113c is located outside the end of the pixel electrode 111c.

[0132] 2A , for example, the EL layer 113 is formed so as to cover the edge of the pixel electrode 111. With this configuration, the aperture ratio can be increased compared to a configuration in which the edge of the island-shaped EL layer 113 is located inside the edge of the pixel electrode 111.

[0133] Furthermore, by covering the side surfaces of the pixel electrodes 111 with the EL layer 113, it is possible to prevent the pixel electrodes 111 from coming into contact with the common electrode 115, thereby preventing short circuits in the light-emitting elements 130. Furthermore, it is possible to increase the distance between the light-emitting region of the EL layer 113 (i.e., the region overlapping with the pixel electrodes 111) and the edge of the EL layer 113, thereby improving the reliability of the light-emitting elements 130.

[0134] The side surfaces of the EL layer 113 are covered with at least the insulating layer 125. The side surfaces of the EL layer 113 may also be covered with the light-shielding layer 135. The side surfaces of the EL layer 113 may also be covered with the light-shielding layer 135 and the insulating layer 127. A portion of the upper surface of the EL layer 113 is covered with the insulating layer 127, the light-shielding layer 135, the insulating layer 125, and the mask layer 118. This prevents the common layer 114 or the common electrode 115 from coming into contact with the side surfaces of the pixel electrode 111 and the EL layer 113, thereby preventing short circuits of the light-emitting element 130. This improves the reliability of the light-emitting element 130.

[0135] In a cross-sectional view, the insulating layer 125 preferably covers at least one side surface of the island-shaped EL layer 113, and more preferably covers both side surfaces of the island-shaped EL layer 113. The insulating layer 125 can be configured to be in contact with each side surface of the island-shaped EL layer 113.

[0136] 2A shows a configuration in which the edge of the pixel electrode 111a is covered with the EL layer 113a, and the insulating layer 125 is in contact with the side surface of the EL layer 113a. Similarly, the edge of the pixel electrode 111b is covered with the EL layer 113b, and the edge of the pixel electrode 111c is covered with the EL layer 113c, and the insulating layer 125 is in contact with the side surface of the EL layer 113b and the side surface of the EL layer 113c.

[0137] The light-shielding layer 135 can be provided on the insulating layer 125, for example, so as to be in contact with the upper surface of the insulating layer 125. The edge of the light-shielding layer 135 can be configured to be flush or approximately flush with the edge of the insulating layer 125.

[0138] The insulating layer 127 is provided on the insulating layer 125 so as to fill the recesses formed in the light-shielding layer 135. The insulating layer 127 can be configured to overlap with a part of the top surface and side surfaces of the EL layer 113 via the insulating layer 125 and the light-shielding layer 135.

[0139] By providing the insulating layer 127, the spaces between the adjacent island-shaped layers can be filled, and therefore the large unevenness of the surface on which the layers (e.g., the carrier injection layer, the common electrode, etc.) formed on the island-shaped layers are formed can be reduced and made flatter, thereby improving the coverage of the carrier injection layer, the common electrode, etc., and preventing the common electrode from being broken.

[0140] In this specification and the like, a step disconnection refers to a phenomenon in which a layer, a film, or an electrode is separated due to the shape of the surface on which it is formed (for example, a step).

[0141] The thickness of the light-shielding layer 135 is preferably 3 nm or more, or 5 nm or more, and 200 nm or less, 150 nm or less, 100 nm or less, 50 nm or less, or 10 nm or less.

[0142] The common layer 114 and the common electrode 115 are provided over the EL layer 113 and the insulating layer 127. Before the insulating layer 127 is provided, a step is generated between a region where the pixel electrode 111 and the EL layer 113 are provided and a region where the pixel electrode 111 and the EL layer 113 are not provided (a region between the light-emitting elements 130). The display device of one embodiment of the present invention includes the insulating layer 127, which can flatten the step and improve the coverage of the common layer 114 and the common electrode 115. Therefore, poor connection due to disconnection of the step can be suppressed. Furthermore, the step can be suppressed from locally thinning the common electrode 115, thereby suppressing an increase in electrical resistance.

[0143] For example, Fig. 2A shows a configuration in which the upper surface of the insulating layer 127 has a convex portion. The upper surface of the insulating layer 127 preferably has a smooth convex curved shape with high flatness. It is more preferable that the upper surface of the insulating layer 127 is flat. The upper surface of the insulating layer 127 may also have a concave portion.

[0144] Furthermore, the insulating layer 125 can be provided so as to be in contact with the island-shaped EL layer 113. This can prevent the island-shaped EL layer 113 from peeling off. When the insulating layer 125 and the EL layer 113 are in close contact with each other, the adjacent island-shaped EL layers 113 are fixed or bonded to each other by the insulating layer 125. This can improve the reliability of the light-emitting element 130. Furthermore, the manufacturing yield of the light-emitting element 130 can be increased.

[0145] Here, the insulating layer 125 has a region in contact with the side surface of the island-shaped EL layer 113 and functions as a protective insulating layer for the EL layer 113. By providing the insulating layer 125, impurities (oxygen, water, and the like) can be prevented from entering the inside from the side surface of the island-shaped EL layer 113, and a highly reliable display device can be provided.

[0146] Next, examples of materials and methods for forming the insulating layer 125, the light-shielding layer 135, and the insulating layer 127 will be described.

[0147] The insulating layer 125 can be an insulating layer containing an inorganic material. Therefore, the insulating layer 125 can be referred to as an inorganic insulating layer, or simply as an inorganic layer. 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. Aluminum oxide is particularly preferable because it has a high etching selectivity with respect to the EL layer and protects the EL layer during the formation of the insulating layer 127, which will be described later. In particular, by using an inorganic insulating film such as an aluminum oxide film, a hafnium oxide film, or a silicon oxide film formed by an ALD method as the insulating layer 125, it is possible to form an insulating layer 125 with few pinholes and excellent protection of the EL layer. The insulating layer 125 may also have a stacked structure of a film formed by an ALD method and a film formed by a sputtering method. For example, the insulating layer 125 may have a stacked structure of an aluminum oxide film formed by an ALD method and a silicon nitride film formed by a sputtering method.

[0148] The insulating layer 125 preferably functions as a barrier insulating layer against at least one of water and oxygen. The insulating layer 125 preferably has a function of suppressing diffusion of at least one of water and oxygen. The insulating layer 125 preferably has a function of capturing or fixing (also referred to as gettering) at least one of water and oxygen.

[0149] The insulating layer 125 has a function as a barrier insulating layer or a gettering function, which can suppress the intrusion of impurities (typically, at least one of water and oxygen) that may diffuse into each light-emitting element from the outside. With this structure, a highly reliable light-emitting element and a highly reliable display device can be provided.

[0150] The insulating layer 125 preferably has a low impurity concentration. This can prevent impurities from entering the EL layer from the insulating layer 125 and causing deterioration of the EL layer. Furthermore, a low impurity concentration in the insulating layer 125 can improve the barrier properties against at least one of water and oxygen. For example, it is desirable that the insulating layer 125 has a sufficiently low hydrogen concentration or a sufficiently low carbon concentration, or preferably both of them.

[0151] Examples of a method for forming the insulating layer 125 include an ALD method, an evaporation method, a sputtering method, a chemical vapor deposition (CVD) method, a pulsed laser deposition (PLD) method, etc. The insulating layer 125 is preferably formed by an ALD method, which has good coverage.

[0152] By increasing the substrate temperature during deposition of the insulating layer 125, the insulating layer 125 can be formed with a low impurity concentration and a high barrier property against at least one of water and oxygen, even if the insulating layer 125 is thin. Therefore, the substrate temperature is preferably 60° C. or higher, more preferably 80° C. or higher, more preferably 100° C. or higher, and still more preferably 120° C. or higher. On the other hand, since the insulating layer 125 is deposited after the island-shaped EL layer is formed, it is preferably formed at a temperature lower than the heat-resistant temperature of the EL layer. Therefore, the substrate temperature is preferably 200° C. or lower, more preferably 180° C. or lower, more preferably 160° C. or lower, more preferably 150° C. or lower, and still more preferably 140° C. or lower.

[0153] Examples of the heat resistance temperature index include a glass transition point, a softening point, a melting point, a thermal decomposition temperature, a 5% weight loss temperature, etc. The heat resistance temperature of the EL layer can be any of these temperatures, preferably the lowest temperature among these.

[0154] The thickness of the insulating layer 125 is preferably, for example, 3 nm or more, 5 nm or more, or 10 nm or more, and 200 nm or less, 150 nm or less, 100 nm or less, or 50 nm or less.

[0155] An insulating layer containing an organic material can be suitably used as the insulating layer 127. Therefore, the insulating layer 127 can be referred to as an organic insulating layer, or simply as an organic layer. A photosensitive organic resin, such as a photosensitive acrylic resin, is preferably used as the organic material. The viscosity of the material for the insulating layer 127 may be 1 cP or more and 1500 cP or less, and preferably 1 cP or more and 12 cP or less. By setting the viscosity of the material for the insulating layer 127 within the above range, the insulating layer 127 having a tapered shape, as described below, can be formed relatively easily. Note that in this specification, the term "acrylic resin" does not refer only to polymethacrylic acid ester or methacrylic resin, but may also refer to acrylic polymers in a broad sense.

[0156] The insulating layer 127 may have a tapered shape on the side surface as described below, and the organic material that can be used for the insulating layer 127 is not limited to the above. For example, acrylic resin, polyimide resin, epoxy resin, imide resin, polyamide resin, polyimideamide resin, silicone resin, siloxane resin, benzocyclobutene resin, phenolic resin, or precursors of these resins may be used for 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 may be used for the insulating layer 127. Alternatively, a photoresist may be used as the photosensitive resin. The photosensitive resin may be a positive-type material or a negative-type material.

[0157] The insulating layer 127 may be made of a material that absorbs visible light. The insulating layer 127 absorbs light emitted from the light-emitting element 130, thereby preventing light from leaking from the light-emitting element 130 to an adjacent light-emitting element 130 through the insulating layer 127 (stray light). This can improve the display quality of the display device. Furthermore, since the display quality can be improved without using a polarizing plate in the display device, the display device can be made lighter and thinner.

[0158] Examples of materials that absorb visible light include materials containing pigments such as black, materials containing dyes, light-absorbing resin materials (e.g., polyimides), and resin materials that can be used for color filters (color filter materials). In particular, using a resin material in which two or more color filter materials are laminated or mixed is preferable because it can enhance the visible light blocking effect. In particular, mixing three or more color filter materials makes it possible to form a black or nearly black resin layer.

[0159] The insulating layer 127 can be formed by, for example, depositing and processing an organic insulating film. In this case, the insulating film that will become the insulating layer 127 can be formed using a wet film-forming method such as spin coating, dipping, spray coating, inkjet printing, dispensing, screen printing, offset printing, doctor knife method, slit coating, roll coating, curtain coating, or knife coating. In particular, it is preferable to form the organic insulating film that will become the insulating layer 127 by spin coating.

[0160] When a photosensitive organic insulating film is used as the insulating film that becomes the insulating layer 127, the insulating film that becomes the insulating layer 127 can be processed by exposure and development processes. Therefore, the insulating film that becomes the insulating layer 127 can be processed without using, for example, dry etching, and damage to the EL layer 113 can be reduced.

[0161] When a photosensitive organic insulating film is used as the insulating film that will become the insulating layer 127, ultraviolet light may be irradiated onto the insulating film that will become the insulating layer 127 in the exposure process. As a result, the EL layer 113 may also be irradiated with ultraviolet light, and the EL layer 113 may be damaged.

[0162] Therefore, for example, by providing a light-shielding film that blocks ultraviolet light, even when a photosensitive organic insulating film is used as the insulating film to be the insulating layer 127 and ultraviolet light is irradiated in an exposure process, the EL layer 113 can be prevented from being damaged by ultraviolet light irradiation. Therefore, the display device of one embodiment of the present invention can be a highly reliable display device. Note that when visible light is irradiated to the insulating film to be the insulating layer 127 in an exposure process for the insulating film to be the insulating layer 127, the light-shielding film blocks visible light. Specifically, the light-shielding film blocks light with a wavelength that is irradiated to the insulating film to be the insulating layer 127 in an exposure process for the insulating film to be the insulating layer 127.

[0163] In this specification and the like, ultraviolet light refers to light in the wavelength region of 10 nm or more and less than 400 nm, and visible light refers to light in the wavelength region of 400 nm or more and less than 700 nm.

[0164] The light-shielding film has a function of absorbing or reflecting light of at least some wavelengths of light irradiated onto the insulating film that will become the insulating layer 127, for example, in an exposure step of the insulating film that will become the insulating layer 127. For example, the light-shielding film has a transmittance of 10% or less, preferably 1% or less, and more preferably 0.1% or less, of light of at least some wavelengths irradiated onto the insulating film that will become the insulating layer 127, in an exposure step of the insulating film that will become the insulating layer 127.

[0165] The light-shielding layer 135 can be formed between adjacent light-emitting elements 130 by processing the light-shielding film by, for example, etching after the insulating layer 127 is formed. The light-shielding layer 135 preferably has a function of absorbing or reflecting light of at least some wavelengths among the light emitted by the light-emitting elements 130. This makes it possible to suppress stray light emitted by the light-emitting elements 130 and improve the display quality of the display device.

[0166] The light-shielding layer 135 may be an insulating layer, but is not limited to this, and may be, for example, a conductive layer or a semiconductor layer. As described above, the light-shielding layer 135 can be formed by processing a light-shielding film by, for example, an etching method. Therefore, it is preferable that the light-shielding layer 135 has good processability by, for example, an etching method.

[0167] The light-shielding layer 135 can be made of a material containing a Group 14 element, such as silicon (e.g., amorphous silicon), carbon, or germanium. For example, the light-shielding layer 135 can be made of a metal, such as molybdenum, titanium, tantalum, tungsten, aluminum, copper, chromium, neodymium, scandium, or an alloy containing these metals. The light-shielding layer 135 can also be made of a nitride containing the above metal (e.g., titanium nitride, chromium nitride, molybdenum nitride, or tungsten nitride), or an oxide containing the above metal (e.g., titanium oxide, chromium oxide, molybdenum oxide, or tungsten oxide).

[0168] Here, in the display device of one embodiment of the present invention, the light-shielding layer 135 is provided over the insulating layer 125. This prevents the light-shielding layer 135 from being in contact with the EL layer 113. Therefore, the range of materials that can be selected for the light-shielding layer 135 can be wider than when the insulating layer 125 is not provided. For example, a material that may damage the EL layer 113 when in contact with the EL layer 113 can be used for the light-shielding layer 135. Furthermore, a method that may damage the EL layer 113 if the EL layer 113 is exposed during the formation of the light-shielding layer 135 can be used for forming the light-shielding layer 135. Furthermore, a conductive material such as a metal can be used for the light-shielding layer 135. Note that, for example, when a material that does not damage the EL layer 113 even when in contact with the EL layer 113 and has insulating properties is used for the light-shielding layer 135, the display device of one embodiment of the present invention can be configured without the insulating layer 125.

[0169] Note that the insulating layer 127 is formed at a temperature lower than the heat resistance temperature of the EL layer 113. The substrate temperature when the insulating layer 127 is formed is typically 200° C. or lower, preferably 180° C. or lower, more preferably 160° C. or lower, more preferably 150° C. or lower, and more preferably 140° C. or lower.

[0170] A light-shielding layer may be provided on the surface of the substrate 120 facing the adhesive layer 122. Various optical members may be disposed on the outside of the substrate 120. Examples of optical members include a polarizing plate, a retardation plate, a light diffusion layer (e.g., a diffusion film), an anti-reflection layer, and a light-collecting film. The outside of the substrate 120 may also be provided with a surface protection layer such as an anti-static film that suppresses the adhesion of dust, a water-repellent film that makes it difficult for dirt to adhere, a hard coat film that suppresses the occurrence of scratches during use, or an impact absorbing layer. For example, a glass layer or a silica layer (SiO ｘ The surface protection layer can be preferably formed of a material such as DLC (diamond-like carbon), aluminum oxide (AlO ｘ ), polyester-based materials, polycarbonate-based materials, etc. may be used for the surface protection layer. It is preferable to use a material with high transmittance to visible light for the surface protection layer. It is also preferable to use a material with high hardness for the surface protection layer.

[0171] 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 element 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.

[0172] 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, or the like), 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, or the like. The substrate 120 may be made of glass having a thickness sufficient to provide flexibility.

[0173] When a circularly polarizing plate is superimposed on a display device, it is preferable to use a substrate having high optical isotropy as a substrate included in the display device. A substrate having high optical isotropy can also be said to have small birefringence (small amount of birefringence).

[0174] 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.

[0175] 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.

[0176] Furthermore, when a film is used as a substrate, the film may absorb water, which may cause changes in shape, such as wrinkles, in the display device. 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.

[0177] The adhesive 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 heat-curable 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. A two-component resin may also be used. Alternatively, an adhesive sheet, for example, may also be used.

[0178] Fig. 2B1 shows a cross-sectional view taken along the dashed line Y1-Y2 in Fig. 1. Fig. 2B1 shows an example of the configuration of the connection section 140.

[0179] In the connection portion 140, a conductive layer 123 is provided over the insulating layer 255c. The conductive layer 123 is electrically connected to the common electrode 115. For the conductive layer 123, it is preferable to use a conductive layer formed using the same material and in the same process as the pixel electrodes 111a, 111b, and 111c.

[0180] 2B1 shows an example in which the common layer 114 is provided on the conductive layer 123, and the conductive layer 123 and the common electrode 115 are electrically connected to each other through the common layer 114. The common layer 114 does not need to be provided in the connection portion 140. In FIG. 2B2, the conductive layer 123 and the common electrode 115 are directly connected to each other. For example, by using a mask for defining a film formation area (also called an area mask or a rough metal mask, to distinguish it from a fine metal mask), the regions where the common layer 114 and the common electrode 115 are formed can be changed.

[0181] Here, the structure of the insulating layer 127 and its vicinity will be described using FIGS. 3A and 3B . FIG. 3A is an enlarged cross-sectional view of a region 139a including the insulating layer 127 between the light-emitting elements 130a and 130b and its periphery. The following description will be given using the insulating layer 127 between the light-emitting elements 130a and 130b as an example, but the same applies to the insulating layer 127 between the light-emitting elements 130b and 130c, and the insulating layer 127 between the light-emitting elements 130c and 130a, etc. Also, FIG. 3B is an enlarged view of the vicinity of the end of the insulating layer 127 on the EL layer 113b shown in FIG. 3A . The following description will sometimes be given using the end of the insulating layer 127 on the EL layer 113b as an example, but the same applies to the end of the insulating layer 127 on the EL layer 113a, the end of the insulating layer 127 on the EL layer 113c, etc.

[0182] 3A , in region 139a, EL layer 113a is provided covering pixel electrode 111a, and EL layer 113b is provided covering pixel electrode 111b. Mask layer 118a is provided in contact with a portion of the upper surface of EL layer 113a, and mask layer 118b is provided in contact with a portion of the upper surface of EL layer 113b. Insulating layer 125 is provided in contact with the upper and side surfaces of mask layer 118a, the side surfaces of EL layer 113a, the upper surface of insulating layer 255c, the upper and side surfaces of mask layer 118b, and the side surfaces of EL layer 113b. Light-shielding layer 135 is provided on insulating layer 125, and insulating layer 127 is provided on light-shielding layer 135. A common layer 114 is provided to cover the EL layer 113 a , the mask layer 118 a , the EL layer 113 b , the mask layer 118 b , the insulating layer 125 , the light-shielding layer 135 , and the insulating layer 127 , and a common electrode 115 is provided on the common layer 114 .

[0183] As described above, the side surface of the pixel electrode 111 preferably has a tapered shape. In this case, the EL layer 113 can have a tapered portion 137 in a cross-sectional view of the display device. Specifically, the EL layer 113 can have the tapered portion 137 between the side surface of the pixel electrode 111 and the insulating layer 125. Figure 3A shows a configuration in which the EL layer 113a has a tapered portion 137a between the side surface of the pixel electrode 111a and the mask layer 118a, and the EL layer 113b has a tapered portion 137b between the side surface of the pixel electrode 111b and the mask layer 118b.

[0184] The taper angle of the side surface of the pixel electrode 111 is less than 90°, preferably 60° or less, and more preferably 45° or less. By forming the side surface of the pixel electrode 111 in such a forward tapered shape, the EL layer 113 provided so as to cover the side surface of the pixel electrode 111 can be formed with good coverage without causing discontinuities, local thinning, or the like in the EL layer 113. Therefore, the display device of one embodiment of the present invention can be a highly reliable display device.

[0185] The taper angle of the tapered portion 137 can be set to a value corresponding to the taper angle of the side surface of the pixel electrode 111. For example, the smaller the taper angle of the side surface of the pixel electrode 111, the smaller the taper angle of the tapered portion 137 can be. The taper angle of the tapered portion 137 is less than 90°, preferably 60° or less, and more preferably 45° or less.

[0186] On the other hand, when the angle of the tapered portion 137 is less than 90°, the tapered portion is more likely to be irradiated with, for example, ultraviolet light in the above-described exposure process of the insulating film that becomes the insulating layer 127, compared to when the angle of the tapered portion 137 is 90° or more. In the display device of one embodiment of the present invention, by providing a light-shielding film that becomes the light-shielding layer 135, irradiation of, for example, ultraviolet light also to the tapered portion 137 of the EL layer 113 can be suppressed, and damage to the EL layer 113 can be suppressed. As described above, the display device of one embodiment of the present invention can improve coverage of the EL layer 113 with respect to the pixel electrode 111 and suppress damage to the EL layer 113 during the manufacturing process. Therefore, the display device of one embodiment of the present invention can be a highly reliable display device.

[0187] 3B , the insulating layer 127 preferably has a tapered shape with a taper angle θ1 on the side surface in a cross-sectional view of the display device. The taper angle θ1 is the angle between the side surface of the insulating layer 127 and the substrate surface. However, the angle is not limited to the substrate surface, and may be the angle between the side surface of the insulating layer 127 and the upper surface of the flat portion of the insulating layer 125, the upper surface of the flat portion of the EL layer 113b, the upper surface of the flat portion of the pixel electrode 111b, or the like.

[0188] The taper angle θ1 of the insulating layer 127 is less than 90°, preferably 60° or less, and more preferably 45° or less. By forming the side edge of the insulating layer 127 in such a forward tapered shape, the common layer 114 and the common electrode 115 provided on the side edge of the insulating layer 127 can be formed with good coverage without causing discontinuities or local thinning of the film. This improves the in-plane uniformity of the common layer 114 and the common electrode 115, thereby improving the display quality of the display device.

[0189] 3A, in a cross-sectional view of the display device, the upper surface of the insulating layer 127 preferably has a convex curved shape. The convex curved shape of the upper surface of the insulating layer 127 preferably bulges gently toward the center. Furthermore, the convex curved portion at the center of the upper surface of the insulating layer 127 preferably smoothly connects to the tapered portion at the side edge. By forming the insulating layer 127 in such a shape, the common layer 114 and the common electrode 115 can be formed with good coverage over the entire insulating layer 127.

[0190] 3A, it is preferable that one end of the insulating layer 127 overlaps the pixel electrode 111a and the other end of the insulating layer 127 overlaps the pixel electrode 111b. This structure allows the end of the insulating layer 127 to be formed on a substantially flat region of the EL layer 113a (EL layer 113b). Therefore, it is relatively easy to form the tapered shape of the insulating layer 127 by processing as described above.

[0191] In the region 139a, for example, the insulating layer 127 is provided as described above, which can prevent discontinuities and locally thin regions from being formed in the common layer 114 and the common electrode 115 from the substantially flat region of the EL layer 113a to the substantially flat region of the EL layer 113b. Therefore, between the light-emitting elements, poor connection due to discontinuities and an increase in electrical resistance due to locally thin regions can be prevented in the common layer 114 and the common electrode 115. This allows the display device of one embodiment of the present invention to have high display quality.

[0192] [Configuration Example 2 of Display Device] Figures 4A, 4B1, and 4B2 are modified examples of the configurations shown in Figures 2A, 2B1, and 2B2, respectively. The display devices shown in Figures 4A, 4B1, and 4B2 differ from the display devices shown in Figures 2A, 2B1, and 2B2 in that the ends of the mask layer 118 and the insulating layer 125 have regions where they coincide or do not substantially coincide with the ends of the insulating layer 127 and the light-shielding layer 135. Specifically, the display devices shown in Figures 4A, 4B1, and 4B2 have regions where the ends of the mask layer 118 and the insulating layer 125 are closer to the center of the EL layer 113 and the conductive layer 123 in a cross-sectional view of the display device than the ends of the insulating layer 127 and the light-shielding layer 135.

[0193] Fig. 5A is an enlarged cross-sectional view of a region 139b including the insulating layer 127 between the light-emitting elements 130a and 130b and the periphery thereof shown in Fig. 4A. Fig. 5B is an enlarged view of the vicinity of the end of the insulating layer 127 on the EL layer 113b shown in Fig. 5A. The following mainly describes configurations different from those in Figs. 3A and 3B.

[0194] 5A and 5B, the mask layer 118b and the insulating layer 125 have a protrusion 116 above the pixel electrode 111b. In a cross-sectional view of the display device, the protrusion 116 is located closer to the center of the EL layer 113b than the ends of the insulating layer 127 and the light-shielding layer 135. The mask layer 118a and the insulating layer 125 also have a similar protrusion 116 above the pixel electrode 111a.

[0195] As shown in Fig. 5B, the protrusion 116 preferably has a tapered shape with a taper angle θ3 on the side surface in a cross-sectional view of the display device. The taper angle θ3 is the angle between the side surface of the mask layer 118b and the substrate surface. However, the taper angle θ3 is not limited to the substrate surface, and may be the angle between the side surface of the mask layer 118b and the upper surface of the flat portion of the EL layer 113b or the upper surface of the flat portion of the pixel electrode 111b. Furthermore, the taper angle θ3 is not limited to the side surface of the mask layer 118b, and may be the angle between the side surface of the insulating layer 125 and the substrate surface.

[0196] The taper angle θ3 of the protrusion 116 is less than 90°, preferably 60° or less, more preferably 45° or less, and even more preferably 20° or less. The taper angle θ3 of the protrusion 116 may be smaller than the taper angle θ2 of the insulating layer 127. By forming the protrusion 116 in such a forward tapered shape, the common layer 114 and the common electrode 115 provided on the protrusion 116 can be formed with good coverage without, for example, causing discontinuities.

[0197] Furthermore, by providing the protrusion 116 below the side edge of the light-shielding layer 135, side etching can be performed near the interface between the side edge of the light-shielding layer 135 and the insulating layer 125, thereby preventing the formation of a cavity between the side edge of the light-shielding layer 135 and the insulating layer 125. If such a cavity is formed, the step caused by the cavity is likely to cause a discontinuity in the common layer 114 and the common electrode 115. However, by providing the insulating layer 125 and the mask layer 118b so as to provide the protrusion 116, the side etching can be prevented from progressing too deeply below the light-shielding layer 135, preventing the cavity from becoming too large. Therefore, by providing the protrusion 116, it is possible to prevent, for example, a discontinuity in the common layer 114 and the common electrode 115 from occurring from the insulating layer 127 to the EL layer 113b.

[0198] Furthermore, the insulating layer 125 may have a region (hereinafter referred to as a countersunk portion 133) in the protruding portion 116 that is thinner than other portions (for example, a portion overlapping with the light-shielding layer 135). Note that, depending on the film thickness of the insulating layer 125, for example, the insulating layer 125 may disappear in the protruding portion 116, and the countersunk portion 133 may be formed up to the mask layer 118b. The insulating layer 125 may also have a similar countersunk portion 133, for example, on the EL layer 113a side.

[0199] 6A is a modified example of the configuration shown in Fig. 2A, and differs from the display device shown in Fig. 2A in that a light-emitting element 130d is included instead of the light-emitting elements 130a, 130b, and 130c. The light-emitting element 130d includes an EL layer 113d as the EL layer 113.

[0200] The EL layer 113d emits, for example, white light. A protective layer 131 is provided to cover the light emitting element 130d, and a protective layer 161 is provided on the protective layer 131. The protective layer 161 functions as a planarizing layer.

[0201] Colored layers 163a, 163b, and 163c are provided on the protective layer 161 so as to have an area overlapping with the light-emitting element 130d. The colored layers 163a, 163b, and 163c can transmit, for example, red, green, or blue light. For example, the colored layer 163a transmits red light, the colored layer 163b transmits green light, and the colored layer 163c transmits blue light. Here, it is assumed that the light-emitting element 130d and the colored layer 163a form a light-emitting unit 160a, the light-emitting element 130d and the colored layer 163b form a light-emitting unit 160b, and the light-emitting element 130d and the colored layer 163c form a light-emitting unit 160c.

[0202] By providing the colored layer 163 so as to have an area overlapping with the light-emitting element 130, the display device can perform full-color display, even if, for example, all of the light-emitting elements 130 in the display device emit white light. Furthermore, by providing the colored layer 163 on the protective layer 161, alignment of the light-emitting elements 130 and the colored layer 163 is easier than, for example, forming a colored layer on the substrate 120 and then bonding the substrate 120 to the substrate provided with the layer 101. This allows for an extremely high-definition display device to be realized. Furthermore, since the distance between the colored layer 163 and the light-emitting element 130 can be shortened, not only color mixing is suppressed but also the viewing angle characteristics of luminance and chromaticity can be improved. As described above, a display device with high display quality can be realized. Note that if there is no need to provide a layer functioning as a planarization layer between the protective layer 161 and the colored layer 163, the protective layer 161 may not be provided.

[0203] Here, the EL layer 113d is separated between different light-emitting elements 130d. This can suitably prevent current from flowing between adjacent light-emitting elements 130d through the EL layer 113d, thereby preventing unintended light emission (also called crosstalk). Therefore, contrast can be increased, and a display device with high display quality can be realized.

[0204] 6A, a light-shielding layer 135 is provided between adjacent light-emitting elements 130d. The light-shielding layer 135 preferably has a function of absorbing or reflecting light of at least some wavelengths among the light emitted by the light-emitting elements 130d. This can prevent light emitted by the light-emitting elements 130d from being incident on the colored layer 163 provided in the adjacent light-emitting unit 160 due to, for example, stray light. For example, it can prevent light emitted by the light-emitting element 130d provided in the light-emitting unit 160a from being incident on the colored layer 163b. This can prevent color mixing and realize a display device with high display quality.

[0205] 6A , the EL layer 113d of the light-emitting unit 160a, the EL layer 113d of the light-emitting unit 160b, and the EL layer 113d of the light-emitting unit 160c preferably have different film thicknesses. This allows a microcavity structure to be realized. For example, the light-emitting element 130d of the light-emitting unit 160a can emit red light that is stronger than other colors, the light-emitting element 130d of the light-emitting unit 160b can emit green light that is stronger than other colors, and the light-emitting element 130d of the light-emitting unit 160c can emit blue light that is stronger than other colors. This allows for improved color purity in the light-emitting unit 160. Note that if the color layer 163 has a sufficiently high light-blocking rate for light of colors other than the desired color, the display device does not need to have a microcavity structure. For example, the EL layer 113d of the light-emitting unit 160a, the EL layer 113d of the light-emitting unit 160b, and the EL layer 113d of the light-emitting unit 160c may all have the same film thickness.

[0206] Figure 6B is a modified example of the configuration shown in Figure 2A, and differs from the display device shown in Figure 2A in that the end of EL layer 113a is located more inward than the end of pixel electrode 111a, the end of EL layer 113b is located more inward than the end of pixel electrode 111b, and the end of EL layer 113c is located more inward than the end of pixel electrode 111c.

[0207] 6B is configured so that the EL layer 113 does not cover the side surfaces of the pixel electrodes 111, thereby preventing steps from occurring in the EL layer 113. This makes it possible to prevent defects such as disconnection of the EL layer 113 from occurring.

[0208] 7A is a modified example of the configuration shown in Fig. 2A, and differs from the display device shown in Fig. 2A in that an insulating layer 117 is provided between adjacent light-emitting elements 130. The insulating layer 117 is provided so as to cover the end of the pixel electrode 111.

[0209] A region of the EL layer 113 that is not in contact with the pixel electrode 111 is provided on the insulating layer 117. Therefore, the display device having the configuration shown in Figure 7A has a region in which the insulating layer 117 is provided between the pixel electrode 111 and the EL layer 113 around the end of the pixel electrode 111.

[0210] A mask layer 118 is provided over the EL layer 113 so as to have a region overlapping with the insulating layer 117. An insulating layer 125 is provided over the mask layer 118 and the insulating layer 117, a light-shielding layer 135 is provided over the insulating layer 125, and an insulating layer 127 is provided over the light-shielding layer 135.

[0211] By providing the insulating layer 117 so as to cover the edges of the pixel electrodes 111, it is possible to prevent short circuits between adjacent pixel electrodes 111. Here, by using an organic material, such as an organic resin, for the insulating layer 117, the edges can be made to have gently curved surfaces. This improves the coverage of layers provided on the insulating layer 117. In addition, the insulating layer 117 can have a flat top surface.

[0212] Examples of organic materials that can be used for the insulating layer 117 include acrylic resin, epoxy resin, polyimide resin, polyamide resin, polyimideamide resin, polysiloxane resin, benzocyclobutene-based resin, and phenol resin.

[0213] Fig. 7B is a modified example of the configuration shown in Fig. 7A, and differs from the display device shown in Fig. 7A in that the edges of the insulating layer 117 are angular and the upper surface of the insulating layer 117 is not flattened. For example, an inorganic material can be used for the insulating layer 117 shown in Fig. 7B.

[0214] Examples of inorganic materials that can be used for the insulating layer 117 include silicon oxide, aluminum oxide, gallium oxide, germanium oxide, yttrium oxide, zirconium oxide, lanthanum oxide, neodymium oxide, hafnium oxide, tantalum oxide, silicon nitride, aluminum nitride, silicon oxynitride, aluminum oxynitride, silicon nitride oxide, and aluminum nitride oxide.

[0215] Next, materials that can be used for the light-emitting element will be described.

[0216] 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. Furthermore, it is preferable to use a conductive film that reflects visible light for the electrode from which light is not extracted. Furthermore, when the display device has a light-emitting element that emits infrared light, it is preferable to use a conductive film that transmits visible light and infrared light for the electrode from which light is extracted, and a conductive film that reflects visible light and infrared light for the electrode from which light is not extracted.

[0217] A conductive film that transmits visible light may also be used for the electrode on the side from which light is not extracted. In this case, it is preferable to place the electrode between the reflective layer and the EL layer. That is, the light emitted from the EL layer may be reflected by the reflective layer and extracted from the display device.

[0218] The pair of electrodes (pixel electrode and common electrode) of the light-emitting element can be formed from a material appropriately selected from metals, alloys, electrically conductive compounds, and mixtures thereof. Specific examples include indium tin oxide (In-Sn oxide, also referred to as ITO), In-Si-Sn oxide (also referred to as ITSO), indium zinc oxide (In-Zn oxide), In-W-Zn oxide, alloys containing aluminum (aluminum alloys) such as an alloy of aluminum, nickel, and lanthanum (Al-Ni-La), and alloys containing silver such as an alloy of silver and magnesium and an alloy of silver, palladium, and copper (Ag-Pd-Cu, also referred to as APC). Other examples of the metals that can be used include aluminum (Al), magnesium (Mg), titanium (Ti), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), gallium (Ga), zinc (Zn), indium (In), tin (Sn), molybdenum (Mo), tantalum (Ta), tungsten (W), palladium (Pd), gold (Au), platinum (Pt), silver (Ag), yttrium (Y), and neodymium (Nd), as well as alloys containing appropriate combinations of these metals. Other examples of the metals that can be used include elements belonging to Group 1 or Group 2 of the periodic table (e.g., lithium (Li), cesium (Cs), calcium (Ca), and strontium (Sr)), rare earth metals such as europium (Eu), and ytterbium (Yb), as well as alloys containing appropriate combinations of these metals, and graphene.

[0219] It is preferable that a microcavity structure is applied to the light-emitting element. Therefore, it is preferable that one of a pair of electrodes of the light-emitting element has an electrode that is transparent and reflective to visible light (semi-transmissive / semi-reflective electrode), and the other has an electrode that is reflective to visible light (reflective electrode). When the light-emitting element has a microcavity structure, light emitted from the light-emitting layer can be resonated between both electrodes, thereby intensifying the light emitted from the light-emitting element.

[0220] The light-emitting layer is a layer containing a light-emitting substance. The light-emitting layer can contain one or more light-emitting substances. As the light-emitting substance, a substance that emits light of blue, purple, blue-purple, green, yellow-green, yellow, orange, red, or the like is appropriately used. Furthermore, a substance that emits near-infrared light can also be used as the light-emitting substance.

[0221] Examples of the light-emitting material include fluorescent materials, phosphorescent materials, TADF materials, and quantum dot materials.

[0222] 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.

[0223] 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.

[0224] The light-emitting layer may contain one or more organic compounds (host materials, assist materials, etc.) in addition to a light-emitting substance (guest material). As the one or more organic compounds, one or both of a hole-transporting material and an electron-transporting material can be used. Furthermore, as the one or more organic compounds, a bipolar material or a TADF material can be used.

[0225] The light-emitting layer preferably includes, for example, a phosphorescent material and a hole-transporting material and an electron-transporting material, which are a combination that easily forms an exciplex. This configuration allows efficient emission using Exciplex-Triple Energy Transfer (ExTET), which is energy transfer from the exciplex to the light-emitting material (phosphorescent material). By selecting a combination that forms an exciplex that emits light at a wavelength that overlaps with the wavelength of the lowest-energy absorption band of the light-emitting material, the energy transfer becomes smooth, allowing efficient emission. This configuration allows the light-emitting element to simultaneously achieve high efficiency, low-voltage operation, and a long life.

[0226] Each of the EL layers 113 a, 113 b, and 113 c may further include a layer containing a substance with high hole-injection properties, a substance with high hole-transport properties, a hole-blocking material, a substance with high electron-transport properties, a substance with high electron-injection properties, an electron-blocking material, or a bipolar substance (a substance with high electron-transport properties and high hole-transport properties), as a layer other than the light-emitting layer.

[0227] The light-emitting element can be made of either a low-molecular-weight compound or a high-molecular-weight compound, and may contain an inorganic compound. Each of the layers constituting the light-emitting element 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.

[0228] For example, the EL layer 113a, the EL layer 113b, and the EL layer 113c may each have 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.

[0229] The common layer 114 may be 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. For example, a carrier injection layer (a hole injection layer or an electron injection layer) may be formed as the common layer 114. Note that the light-emitting element does not necessarily have to have the common layer 114.

[0230] Each of the EL layers 113a, 113b, and 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 element.

[0231] 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).

[0232] 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 substance having a hole mobility of 1 / Vs or more is preferred. Note that other substances can also be used as long as they have a higher hole transporting property than electron transporting property. As the hole transporting material, a material having a high hole transporting property, such as a π-electron-rich heteroaromatic compound (e.g., a carbazole derivative, a thiophene derivative, or a furan derivative), or an aromatic amine (a compound having an aromatic amine skeleton), is preferred.

[0233] The electron transport layer is a layer that transports electrons injected from the cathode by the electron injection layer to the light emitting layer. The electron transport layer is a layer that contains an electron transporting material. The electron transporting material is a material having a molecular weight of 1×10 −６ cm ２ / Vs or more is preferred. Note that other materials can also be used as long as they have a higher electron transporting property than holes. Examples of the electron-transporting material include metal complexes having a quinoline skeleton, metal complexes having a benzoquinoline skeleton, metal complexes having an oxazole skeleton, and metal complexes having a thiazole skeleton, as well as oxadiazole derivatives, triazole derivatives, imidazole derivatives, oxazole derivatives, thiazole derivatives, phenanthroline derivatives, quinoline derivatives having a quinoline ligand, benzoquinoline derivatives, quinoxaline derivatives, dibenzoquinoxaline derivatives, pyridine derivatives, bipyridine derivatives, pyrimidine derivatives, and other π-electron-deficient heteroaromatic compounds including nitrogen-containing heteroaromatic compounds.

[0234] 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).

[0235] The electron injection layer may be formed of, for example, lithium, cesium, ytterbium, lithium fluoride (LiF), cesium fluoride (CsF), calcium fluoride (CaF ｘ , x is an arbitrary number), 8-(quinolinolato)lithium (abbreviation: Liq), 2-(2-pyridyl)phenolatolithium (abbreviation: LiPP), 2-(2-pyridyl)-3-pyridinolatolithium (abbreviation: LiPPy), 4-phenyl-2-(2-pyridyl)phenolatolithium (abbreviation: LiPPP), lithium oxide (LiO ｘ The electron injection layer may be formed of an alkali metal, an alkaline earth metal, or a compound thereof, such as lithium fluoride or cesium carbonate. 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 as a first layer and ytterbium is provided as a second layer.

[0236] 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.

[0237] The organic compound having an unshared electron pair preferably has a lowest unoccupied molecular orbital (LUMO) level of −3.6 eV to −2.3 eV. Generally, the highest occupied molecular orbital (HOMO) level and the LUMO level of an organic compound can be estimated by cyclic voltammetry (CV), photoelectron spectroscopy, optical absorption spectroscopy, inverse photoelectron spectroscopy, or the like.

[0238] For example, 4,7-diphenyl-1,10-phenanthroline (abbreviation: BPhen), 2,9-di(naphthalen-2-yl)-4,7-diphenyl-1,10-phenanthroline (abbreviation: NBPhen), diquinoxalino[2,3-a:2',3'-c]phenazine (abbreviation: HATNA), or 2,4,6-tris[3'-(pyridin-3-yl)biphenyl-3-yl]-1,3,5-triazine (abbreviation: TmPPPyTz) can be used as the organic compound having an unshared electron pair. Note that NBPhen has a higher glass transition point (Tg) and is superior in heat resistance compared to BPhen.

[0239] In addition, when a light-emitting element having a tandem structure is fabricated, a charge-generating layer (also referred to as an intermediate layer) is provided between two light-emitting units. The intermediate layer has a function of injecting electrons into one of the two light-emitting units and injecting holes into the other when a voltage is applied between a pair of electrodes.

[0240] For example, a material applicable to an electron injection layer, such as lithium, can be suitably used for the charge generation layer. For example, a material applicable to a hole injection layer can be suitably used for the charge generation layer. For example, a layer containing a hole transport material and an acceptor material (electron acceptor material) can be used for the charge generation layer. For example, a layer containing an electron transport material and a donor material can be used for the charge generation layer. By forming such a charge generation layer, an increase in driving voltage can be suppressed when light-emitting units are stacked.

[0241] [Example 1 of Manufacturing Method of Display Device] An example of a manufacturing method of the display device shown in Fig. 2A and Fig. 2B2 will be described with reference to Fig. 8A to Fig. 12C. Fig. 8A to Fig. 12C show a cross-sectional view taken along dashed lines X1-X2 and Y1-Y2 in Fig. 1 side by side.

[0242] Thin films (insulating films, semiconductor films, conductive films, etc.) constituting the display device can be formed using a sputtering method, a CVD method, a vacuum deposition method, a PLD method, an ALD method, etc. CVD methods include a plasma enhanced chemical vapor deposition (PECVD) method and a thermal CVD method. One type of thermal CVD method is a metal organic chemical vapor deposition (MOCVD) method.

[0243] Furthermore, thin films (insulating films, semiconductor films, conductive films, etc.) constituting the display device can be formed by methods such as spin coating, dipping, spray coating, inkjet, dispensing, screen printing, offset printing, doctor knife method, slit coating, roll coating, curtain coating, or knife coating.

[0244] In particular, the light-emitting element can be fabricated using a vacuum process such as vapor deposition, or a solution process such as spin coating or inkjet printing. 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 (hole injection layer, hole transport layer, light-emitting layer, electron transport layer, electron injection layer, etc.) can be formed by a vapor deposition method (e.g., vacuum deposition), a coating method (dip coating, die coating, bar coating, spin coating, spray coating, etc.), a printing method (inkjet printing, screen (stencil printing) method, offset (lithographic printing) method, flexography (relief printing) method, gravure printing, microcontact printing, etc.), etc.

[0245] Furthermore, when processing the thin film that constitutes the display device, it can be processed using, for example, a photolithography method. Alternatively, the thin film may be processed using a nanoimprint method, a sandblasting method, a lift-off method, or the like. Alternatively, the island-shaped thin film may be directly formed by a film formation method using a shielding mask such as a metal mask.

[0246] 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, 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.

[0247] In photolithography, the light used for exposure may be, for example, i-line (wavelength 365 nm), g-line (wavelength 436 nm), h-line (wavelength 405 nm), or a mixture of these. In addition to the above-mentioned configurations, the light used for exposure in photolithography may also be ultraviolet light, KrF laser light (wavelength 248 nm), or ArF laser light (wavelength 193 nm). Exposure may also be performed by immersion exposure technology. Extreme ultraviolet light (EUV) or X-rays may also be used as the light used for exposure. An electron beam may 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.

[0248] The thin film can be etched by dry etching, wet etching, sandblasting, or the like.

[0249] 8A, an insulating layer 255a, an insulating layer 255b, and an insulating layer 255c are formed in this order on the transistor-including layer 101. Next, as shown in FIG. 8A, the pixel electrodes 111a, 111b, and 111c, and the conductive layer 123 are formed on the insulating layer 255c, an EL film 113A is formed on the pixel electrodes 111a, 111b, and 111c, a mask film 118A is formed on the EL film 113A, and a mask film 119A is formed on the mask film 118A.

[0250] 8A , in the cross-sectional view between Y1 and Y2, the end of the EL film 113A on the connection portion 140 side is located inside the end of the mask film 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), the regions formed by the EL film 113A and the mask films 118A and 119A can be varied. In one embodiment of the present invention, a light-emitting element is formed using a resist mask. However, by combining the resist mask with an area mask as described above, the light-emitting element can be manufactured by a relatively simple process.

[0251] The pixel electrodes 111a, 111b, and 111c can be formed by, for example, sputtering or vacuum deposition.

[0252] The side surfaces of the pixel electrodes 111a, 111b, and 111c are preferably tapered, which improves the coverage of layers formed on the pixel electrodes 111a, 111b, and 111c, thereby increasing the manufacturing yield of light-emitting elements.

[0253] The EL film 113A is a layer that will later become the EL layer 113a and includes at least a film (light-emitting film) containing a light-emitting compound. The EL film 113A preferably includes a light-emitting film and a film that functions as a carrier transport layer on the light-emitting film. This prevents the light-emitting film from being exposed to the outermost surface during the manufacturing process of the display device, thereby reducing damage to the light-emitting film. This improves the reliability of the display device.

[0254] The EL film 113A may also have a structure in which one or more films functioning as a hole injection layer, a hole transport layer, a hole blocking layer, an electron blocking layer, an electron transport layer, or an electron injection layer are stacked. For example, the EL film 113A may have a structure in which a film functioning as a hole injection layer, a film functioning as a hole transport layer, a light-emitting film, and a film functioning as an electron transport layer are stacked in this order. Alternatively, the EL film 113A may have a structure in which a film functioning as an electron injection layer, a film functioning as an electron transport layer, a light-emitting film, and a film functioning as a hole transport layer are stacked in this order.

[0255] The EL film 113A 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 EL film 113A is preferably formed by a vapor deposition method. When forming a film by a vapor deposition method, a premix material may be used. Note that in this specification and the like, a premix material is a composite material in which multiple materials are blended or mixed in advance.

[0256] The mask films 118A and 119A are made of a film that is highly resistant to the processing conditions of the EL film 113A and the EL films 113B and 113C formed in later steps, specifically, a film that has a large etching selectivity with respect to various EL layers.

[0257] The mask films 118A and 119A can be formed by, for example, sputtering, ALD (thermal ALD, PEALD), CVD, or vacuum deposition. The mask film 118A, which is formed in contact with the EL layer, is preferably formed using a method that causes less damage to the EL layer than the method used to form the mask film 119A. For example, the mask film 118A is preferably formed using ALD or vacuum deposition rather than sputtering. The mask films 118A and 119A are formed at a temperature lower than the heat-resistant temperature of the EL layer. The substrate temperature during the formation of the mask films 118A and 119A is typically 200°C or lower, preferably 150°C or lower, more preferably 120°C or lower, more preferably 100°C or lower, and even more preferably 80°C or lower.

[0258] It is preferable to use a film that can be removed by wet etching for the mask films 118A and 119A. By using wet etching, damage to the EL film 113A during processing of the mask films 118A and 119A can be reduced compared to when dry etching is used.

[0259] It is also preferable to use a film for the mask film 118A that has a large etching selectivity with respect to the mask film 119A.

[0260] In the manufacturing method of a display device according to one embodiment of the present invention, it is desirable that the layers constituting the EL layer (such as a hole injection layer, a hole transport layer, a light-emitting layer, and an electron transport layer) are not easily processed in the processing steps of the various mask layers, and that the various mask layers are not easily processed in the processing steps of the layers constituting the EL layer. It is desirable to select the material and processing method of the mask layer and the processing method of the EL layer in consideration of these points.

[0261] Although the present embodiment shows an example in which the mask film is formed to have a two-layer structure, the mask film may have a single-layer structure or a laminated structure of three or more layers.

[0262] The mask film 118A and the mask film 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.

[0263] The mask films 118A and 119A can each 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 mask films 118A and 119A is preferable because it can prevent ultraviolet light from being irradiated onto the EL layer and thereby prevent deterioration of the EL layer.

[0264] Furthermore, metal oxides such as In—Ga—Zn oxide can be used for the mask films 118A and 119A. For example, an In—Ga—Zn oxide film can be formed as the mask film 118A or the mask film 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), or indium gallium tin zinc oxide (In—Ga—Sn—Zn oxide) can be used. Furthermore, for example, indium tin oxide containing silicon can also be used.

[0265] Note that, 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.

[0266] Furthermore, the mask films 118A and 119A can each be made of various inorganic insulating films that can be used for the protective layer 131. 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, or silicon oxide can be used for the mask films 118A and 119A. For example, an aluminum oxide film can be formed as the mask film 118A or the mask film 119A using the ALD method. Using the ALD method is preferable because it can reduce damage to the underlying layer (particularly the EL layer).

[0267] For example, an inorganic insulating film (e.g., an aluminum oxide film) formed using the ALD method can be used as the mask film 118A, and an inorganic film (e.g., an In-Ga-Zn oxide film, an aluminum film, or a tungsten film) formed using the sputtering method can be used as the mask film 119A.

[0268] The same inorganic insulating film can be used for both the mask film 118A and the insulating layer 125 to be formed later. For example, an aluminum oxide film formed using an ALD method can be used for both the mask film 118A and the insulating layer 125. The same film formation conditions can be applied to the mask film 118A and the insulating layer 125. For example, by forming the mask film 118A under the same conditions as the insulating layer 125, the mask film 118A can be made into an insulating layer with a high barrier property against at least one of water and oxygen. However, this is not limited thereto, and different film formation conditions can be applied to the mask film 118A and the insulating layer 125.

[0269] One or both of the mask films 118A and 119A may be made of a material that is soluble in a chemically stable solvent. Materials that are soluble in water or alcohol are particularly suitable. 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 in a short time, thereby reducing thermal damage to the EL layer.

[0270] The mask film 118A and the mask film 119A may each 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.

[0271] The mask film 118A and the mask film 119A may each 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.

[0272] 8A, a resist mask 190a is formed on the mask film 119A. The resist mask can be formed by applying a photosensitive resin (photoresist) and then performing exposure and development.

[0273] The resist mask may be made of either a positive resist material or a negative resist material.

[0274] The resist mask 190a is provided at a position overlapping the pixel electrode 111a. Preferably, the resist mask 190a has an island-shaped pattern for each sub-pixel 110a. Alternatively, the resist mask 190a may have a strip-shaped pattern for a plurality of sub-pixels 110a arranged in a line (arranged in the Y direction in FIG. 1).

[0275] Here, if the resist mask 190a is formed so that the end of the resist mask 190a is positioned outside the end of the pixel electrode 111a, the end of the EL layer 113a to be formed later can be positioned outside the end of the pixel electrode 111a.

[0276] Note that the resist mask 190a is preferably provided also in a position overlapping with the connection portion 140. This can prevent the conductive layer 123 from being damaged during the manufacturing process of the display device.

[0277] 8B, the mask film 119A is processed using a resist mask 190a to form a mask layer 119a. The mask layer 119a remains on the pixel electrodes 111a and the conductive layer 123.

[0278] When etching the mask film 119A, it is preferable to use etching conditions with a high selectivity so that the mask film 118A is not processed by the etching. Furthermore, since the EL film 113A is not exposed when processing the mask film 119A, the range of processing methods available is wider than when processing the mask film 118A. Specifically, even when a gas containing oxygen is used as an etching gas when processing the mask film 119A, deterioration of the EL film 113A can be further suppressed.

[0279] 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 can be removed by ashing using oxygen gas and CF ４ , C ４ F ８ , SF ６ , CHF ３ , Cl ２ , H ２ O, BCl ３Alternatively, a noble gas (also referred to as a rare gas) may be used. For example, He may be used as the noble gas. Alternatively, the resist mask 190a may be removed by wet etching. At this time, the mask film 118A is located on the outermost surface, and the EL film 113A is not exposed. Therefore, damage to the EL film 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.

[0280] Next, as shown in FIG. 8C, the mask film 118A is processed using the mask layer 119a as a mask (also called a hard mask) to form a mask layer 118a.

[0281] The mask films 118A and 119A can be processed by wet etching or dry etching, respectively, and are preferably processed by anisotropic etching.

[0282] Compared to the case of using dry etching, the use of wet etching can reduce damage to the EL film 113A during processing of the mask films 118A and 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.

[0283] When dry etching is used, deterioration of the EL film 113A can be suppressed by not using a gas containing oxygen as the etching gas. ４ , C ４ F ８ , SF ６ , CHF ３ , Cl ２ , H ２ O, BCl ３ It is preferable to use a gas containing a noble gas as the etching gas. An example of the noble gas is He.

[0284] For example, when an aluminum oxide film formed by the ALD method is used as the mask film 118A, CHF ３ The mask film 118A can be processed by dry etching using He. When an In-Ga-Zn oxide film formed by sputtering is used as the mask film 119A, the mask film 119A can be processed by wet etching using diluted phosphoric acid. ４ The mask film 119A may be processed by dry etching using diluted phosphoric acid and Ar. Alternatively, the mask film 119A may be processed by wet etching using diluted phosphoric acid. When a tungsten film formed by sputtering is used as the mask film 119A, CF ４ and O ２ , C.F. ６ and O ２ , C.F. ４ and Cl ２ and O ２ , or CF ６ and Cl ２ and O ２ The mask film 119A can be processed by dry etching using the above.

[0285] Next, as shown in FIG. 8C , the EL film 113A is processed by an etching process using the mask layers 119a and 118a as hard masks to form an EL layer 113a. If the side surface of the pixel electrode 111a has a tapered shape, a tapered portion 137a is formed in the EL layer 113a. The tapered portion 137a is formed, for example, between the side surface of the pixel electrode 111a and the mask layer 118a. As described above, the taper angle of the tapered portion 137a can be less than 90°.

[0286] 8C , a layered structure of the EL layer 113a, the mask layer 118a, and the mask layer 119a remains on the pixel electrode 111a. In addition, in the region corresponding to the connection portion 140, a layered structure of the mask layer 118a and the mask layer 119a remains on the conductive layer 123.

[0287] 8C shows an example in which the edge of the EL layer 113a is positioned outside the edge of the pixel electrode 111a. This configuration can increase the aperture ratio of the pixel. Although not shown in FIG. 8C, the etching process may result in the formation of a recess in the insulating layer 255c in a region that does not overlap with the EL layer 113a.

[0288] Furthermore, because the EL layer 113a covers the top and side surfaces of the pixel electrode 111a, subsequent processes can be performed without exposing the pixel electrode 111a. If the edges of the pixel electrode 111a are exposed, corrosion may occur, for example, during an etching process. Products resulting from corrosion of the pixel electrode 111a may be unstable, dissolving in solution during wet etching or scattering into the atmosphere during dry etching. If the products dissolve in solution or scatter into the atmosphere, they may adhere to the processed surface and the side surfaces of the EL layer 113a, adversely affecting the characteristics of the light-emitting element or forming leak paths between multiple light-emitting elements. Furthermore, in areas where the edges of the pixel electrode 111a are exposed, the adhesion between adjacent layers may be reduced, potentially leading to film peeling of the EL layer 113a or the pixel electrode 111a.

[0289] Therefore, by configuring the EL layer 113a to cover the upper and side surfaces of the pixel electrode 111a, for example, the yield of the light-emitting element can be improved, and the display quality of the light-emitting element can be improved.

[0290] The EL film 113A may be processed using the resist mask 190a, and then the resist mask 190a may be removed.

[0291] The EL film 113A is preferably processed by anisotropic etching, particularly anisotropic dry etching, or wet etching may be used.

[0292] When dry etching is used, deterioration of the EL film 113A can be suppressed by not using a gas containing oxygen as the etching gas.

[0293] Alternatively, a gas containing oxygen may be used as the etching gas. By using an etching gas containing 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 EL film 113A. Furthermore, problems such as adhesion of reaction products that occur during etching can be reduced.

[0294] When dry etching is used, for example, H ２ , C.F. ４ , C ４ F ８ , SF ６ , CHF ３ , Cl ２ , H ２ O, BCl ３ It is preferable to use a gas containing one or more of the noble 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, H ２ and a gas containing Ar, or CF ４ A gas containing CF and He can be used as an etching gas. ４ A gas containing He and oxygen can be used as the etching gas.

[0295] Through the above steps, the EL film 113A, the mask film 118A, and the mask film 119A can be removed in the areas not overlapping with the resist mask 190a.

[0296] Next, as shown in FIG. 9A, an EL film 113B is formed on the mask layer 119a, the pixel electrodes 111b, and the pixel electrodes 111c, a mask film 118B is formed on the EL film 113B, and a mask film 119B is formed on the mask film 118B.

[0297] As shown in FIG. 9A, in the cross section taken along line Y1-Y2, the end of the EL film 113B on the connection portion 140 side is located more inward than the end of the mask film 118B.

[0298] The EL film 113B is a layer that will later become the EL layer 113b. The EL layer 113b emits light of a different color from the EL layer 113a. The configuration and materials that can be applied to the EL layer 113b are the same as those of the EL layer 113a. The EL film 113B can be formed using the same method as the EL film 113A.

[0299] The mask film 118B can be formed using a material that can be used for the mask film 118A. The mask film 119B can be formed using a material that can be used for the mask film 119A.

[0300] Next, as shown in FIG. 9A, a resist mask 190b is formed on the mask film 119B.

[0301] The resist mask 190b is provided at a position overlapping the pixel electrode 111b. The resist mask 190b may also be provided at a position overlapping the region that will become the connection portion 140 later.

[0302] Next, by performing the same steps as those described with reference to FIGS. 8B and 8C, the regions of the EL film 113B, the mask film 118B, and the mask film 119B that are not overlapped with the resist mask 190b are removed.

[0303] As a result, as shown in FIG. 9B , a layered structure of the EL layer 113b, the mask layer 118b, and the mask layer 119b remains on the pixel electrode 111b. Furthermore, in the region corresponding to the connection portion 140, a layered structure of the mask layer 118a and the mask layer 119a remains on the conductive layer 123. Here, if the side surface of the pixel electrode 111b has a tapered shape, a tapered portion 137b is formed in the EL layer 113b. The tapered portion 137b is formed, for example, between the side surface of the pixel electrode 111b and the mask layer 118b. As described above, the taper angle of the tapered portion 137b can be less than 90°.

[0304] Next, as shown in FIG. 9B, an EL film 113C is formed on the mask layer 119a, the mask layer 119b, and the pixel electrode 111c, a mask film 118C is formed on the EL film 113C, and a mask film 119C is formed on the mask film 118C.

[0305] As shown in FIG. 9B, in the cross-sectional view taken along line Y1-Y2, the end of the EL film 113C on the connection portion 140 side is located more inward than the end of the mask film 118C.

[0306] The EL film 113C is a layer that will later become the EL layer 113c. The EL layer 113c emits light of a different color from the EL layers 113a and 113b. The configuration, materials, etc. that can be applied to the EL layer 113c are the same as those of the EL layer 113a. The EL film 113C can be formed using the same method as the EL film 113A.

[0307] The mask film 118C can be formed using a material that can be used for the mask film 118A. The mask film 119C can be formed using a material that can be used for the mask film 119A.

[0308] Next, as shown in FIG. 9B, a resist mask 190c is formed on the mask film 119C.

[0309] The resist mask 190c is provided at a position overlapping the pixel electrode 111c. The resist mask 190c may also be provided at a position overlapping the region that will become the connection portion 140 later.

[0310] Next, by performing the same steps as those described with reference to FIGS. 8B and 8C, the regions of the EL film 113C, the mask film 118C, and the mask film 119C that are not overlapped with the resist mask 190c are removed.

[0311] As a result, as shown in FIG. 9C , a layered structure of the EL layer 113c, the mask layer 118c, and the mask layer 119c remains on the pixel electrode 111c. Furthermore, in the region corresponding to the connection portion 140, a layered structure of the mask layer 118a and the mask layer 119a remains on the conductive layer 123. If the side surface of the pixel electrode 111c has a tapered shape, a tapered portion 137c is formed in the EL layer 113c. The tapered portion 137c is formed, for example, between the side surface of the pixel electrode 111c and the mask layer 118b. The taper angle of the tapered portion 137c can be less than 90°, similar to the taper angles of the tapered portions 137a and 137b.

[0312] The side end portions of the EL layers 113 a, 113 b, and 113 c 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.

[0313] As described above, by processing each EL film using photolithography, the distance between each pixel can be narrowed to 8 μm or less, 5 μm or less, 3 μm or less, 2 μm or less, or 1 μm or less. Here, the distance between each pixel can be defined as, for example, the distance between the opposing ends of two adjacent layers among the EL layer 113a, the EL layer 113b, and the EL layer 113c. By narrowing the distance between each pixel in this way, a display device with high definition and a large aperture ratio can be provided.

[0314] 10A , the mask layers 119a, 119b, and 119c are removed, thereby exposing the mask layer 118a on the pixel electrode 111a, the mask layer 118b on the pixel electrode 111b, and the mask layer 118c on the pixel electrode 111c. Furthermore, the mask layer 118a is exposed on the conductive layer 123.

[0315] It is also possible to proceed to the step of forming the insulating film 125A without removing the mask layers 119a, 119b, and 119c.

[0316] The mask layer removal process can be performed using the same method as the mask film processing process. In particular, by using a wet etching method, damage to the EL layers 113 a, 113 b, and 113 c during mask layer removal can be reduced compared to when a dry etching method is used.

[0317] The mask layer may also be removed by dissolving it in a solvent such as water or alcohol, including ethyl alcohol, methyl alcohol, isopropyl alcohol (IPA), and glycerin.

[0318] After removing the mask layer, 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 or higher and 200°C or lower, preferably 60°C or higher and 150°C or lower, and more preferably 70°C or higher and 120°C or lower. A reduced pressure atmosphere is preferred because it allows drying at a lower temperature.

[0319] Next, as shown in FIG. 10A, an insulating film 125A is formed to cover the EL layers 113a, 113b, 113c, mask layers 118a, 118b, and 118c.

[0320] The insulating film 125A is a layer that will later become the insulating layer 125. Therefore, the insulating film 125A can be made of a material that can be used for the insulating layer 125. The thickness of the insulating film 125A is preferably 3 nm or more, 5 nm or more, or 10 nm or more, and 200 nm or less, 150 nm or less, 100 nm or less, or 50 nm or less.

[0321] Since the insulating film 125A is formed in contact with the side surface of the EL layer 113, it is preferable that the insulating film 125A be formed by a method that causes little damage to the EL layer 113. The insulating film 125A is formed at a temperature lower than the heat-resistant temperature of the EL layer 113. The substrate temperature when forming the insulating film 125A is typically 200° C. or lower, preferably 180° C. or lower, more preferably 160° C. or lower, more preferably 150° C. or lower, and more preferably 140° C. or lower. Note that the steps after the formation of the insulating film 125A are also performed at temperatures lower than the heat-resistant temperature of the EL layer 113.

[0322] The insulating film 125A can be formed as an inorganic insulating film using, for example, an ALD method, a vapor deposition method, a sputtering method, a CVD method, or a PLD method. For example, it is preferable to form the insulating film 125A using an ALD method. Using the ALD method is preferable because it can reduce film formation damage and form a film with high coverage. Here, the insulating film 125A can be formed using the same material and method as the mask layers 118a, 118b, and 118c. In this case, the boundaries between the insulating film 125A and the mask layers 118a, 118b, and 118c may become unclear.

[0323] Next, as shown in FIG. 10A, a light-shielding film 135A is formed on the insulating film 125A.

[0324] The light-shielding film 135A is a layer that will later become the light-shielding layer 135. Therefore, the light-shielding film 135A can be made of a material that can be used for the light-shielding layer 135, such as silicon. The film thickness of the light-shielding film 135A is preferably 3 nm or more, or 5 nm or more, and 200 nm or less, 150 nm or less, 100 nm or less, 50 nm or less, or 10 nm or less. The light-shielding film 135A can be formed by a method similar to that used to form the insulating film 125A.

[0325] Next, as shown in FIG. 10B, an insulating film 127A is formed on the light-shielding film 135A by a coating method.

[0326] The insulating film 127A is a film that will become the insulating layer 127 in a later process, and the above-mentioned organic material can be used for the insulating film 127A. A photosensitive organic resin, such as a photosensitive acrylic resin, is preferably used as the organic material. The viscosity of the insulating film 127A may be 1 cP or more and 1500 cP or less, and preferably 1 cP or more and 12 cP or less. By setting the viscosity of the insulating film 127A within the above range, the insulating layer 127 having a tapered shape as shown in FIGS. 3A and 5A can be formed relatively easily.

[0327] The method for forming the insulating film 127A is not particularly limited, and the insulating film 127A can be formed using a wet film formation method such as spin coating, dipping, spray coating, inkjet printing, dispensing, screen printing, offset printing, doctor knife method, slit coating, roll coating, curtain coating, or knife coating. In particular, it is preferable to form the insulating film 127A by spin coating.

[0328] Furthermore, it is preferable to perform heat treatment after forming the insulating film 127A by a coating method. The heat treatment is performed at a temperature lower than the heat resistance temperature of the EL layer. The substrate temperature during the heat treatment may be 50° C. or higher and 200° C. or lower, preferably 60° C. or higher and 150° C. or lower, and more preferably 70° C. or higher and 120° C. or lower. This allows the solvent contained in the insulating film 127A to be removed.

[0329] 10C , a portion of the insulating film 127A is exposed to light. For example, ultraviolet light is irradiated onto the portion of the insulating film 127A. Alternatively, visible light may be irradiated onto the portion of the insulating film 127A. In the following description, it is assumed that the insulating film 127A and a layer formed from the insulating film 127A are exposed to ultraviolet light.

[0330] Here, when a positive acrylic resin is used for the insulating film 127A, ultraviolet light is irradiated using a mask onto a region where the insulating layer 127 will not be formed in a later step. Since the insulating layer 127 is formed in a region sandwiched between any two of the pixel electrodes 111a, 111b, and 111c, ultraviolet light is irradiated onto the pixel electrodes 111a, 111b, and 111c using a mask.

[0331] 10C shows an example in which a positive photosensitive organic insulating film is used as insulating film 127A and ultraviolet light is irradiated onto the region where insulating layer 127 is not formed, but the present invention is not limited to this. For example, a negative photosensitive organic insulating film may be used as insulating film 127A. In this case, ultraviolet light is irradiated onto the region where insulating layer 127 is formed.

[0332] If the light-shielding film 135A is not provided, the EL layer 113 may be irradiated with ultraviolet light when the insulating film 127A is exposed to light. This may damage the EL layer 113. On the other hand, in the method for manufacturing a display device of one embodiment of the present invention, the light-shielding film 135A blocks ultraviolet light. Therefore, the EL layer 113 can be prevented from being damaged by irradiation with ultraviolet light when the insulating film 127A is exposed to light. Therefore, a highly reliable display device can be manufactured.

[0333] Furthermore, when the EL layer 113 is formed to have the tapered portion 137, the EL layer 113 is more likely to be irradiated with ultraviolet light during exposure of the insulating film 127A than when the EL layer 113 is formed so that the portion corresponding to the tapered portion 137 is vertical in a cross-sectional view of the display device. Therefore, by providing the light-shielding film 135A, the tapered portion 137 can also be prevented from being irradiated with ultraviolet light, and damage to the EL layer 113 can be suppressed. As described above, in the manufacturing method of a display device according to one embodiment of the present invention, the coverage of the EL layer 113 with respect to the pixel electrode 111 can be improved and damage to the EL layer 113 can be suppressed. Therefore, a highly reliable display device can be manufactured.

[0334] The light-shielding film 135A has a function of absorbing or reflecting light of at least some wavelengths of light irradiated onto the insulating film 127A in, for example, an exposure step of the insulating film 127A. For example, the light-shielding film 135A has a transmittance of 10% or less, preferably 1% or less, and more preferably 0.1% or less, for light of at least some wavelengths of light irradiated onto the insulating film 127A in an exposure step of the insulating film 127A.

[0335] Forming the light-shielding film 135A on the insulating film 125A, which can be an inorganic insulating film, can prevent the light-shielding film 135A from contacting the EL layer 113. This allows for a wider range of material options for the light-shielding film 135A than when the insulating film 125A is not formed. For example, a material that may damage the EL layer 113 when in contact with the EL layer 113 can be used for the light-shielding film 135A. Furthermore, a method that may damage the EL layer 113 if the EL layer 113 is exposed during the formation of the light-shielding film 135A can be used to form the light-shielding film 135A. Furthermore, the light-shielding film 135A can be formed from a conductive material such as a metal. For example, if the light-shielding film 135A is formed from an insulating material that does not damage the EL layer 113 when in contact with the EL layer 113, the insulating film 125A may not be formed.

[0336] 11A, development is performed to remove the exposed areas of the insulating film 127A, thereby forming an insulating layer 127B. The insulating layer 127B is formed in a region sandwiched between any two of the pixel electrodes 111a, 111b, and 111c. When an acrylic resin is used for the insulating film 127A, it is preferable to use an alkaline solution as the developer, such as a tetramethylammonium hydroxide aqueous solution (TMAH).

[0337] 11B, the entire substrate is exposed to ultraviolet light, and the insulating layer 127B is preferably irradiated with the ultraviolet light. The energy density of the exposure is 0 mJ / cm. ２ Larger than 800 mJ / cm ２ or less, 0 mJ / cm ２ Greater than 500 mJ / cm ２ It is preferable that the following is satisfied. By performing such exposure after development, the transparency of the insulating layer 127B can be improved in some cases. Furthermore, the substrate temperature required for a heat treatment for deforming the side surfaces of the insulating layer 127B into a tapered shape in a later step can be reduced in some cases. By providing the light-shielding film 135A, it is possible to prevent the EL layer 113 from being damaged by irradiation of ultraviolet light to the EL layer 113 in this step as well.

[0338] 11C , heat treatment is performed to transform the insulating layer 127B into an insulating layer 127 having tapered side surfaces. The heat treatment is performed at a temperature lower than the heat resistance temperature of the EL layer. The substrate temperature during the heat treatment may be 50° C. or higher and 200° C. or lower, preferably 60° C. or higher and 150° C. or lower, and more preferably 70° C. or higher and 130° C. or lower. The substrate temperature during the heat treatment in this step is preferably higher than that during the heat treatment after application of the insulating layer 127. This can improve the adhesion of the insulating layer 127 to the insulating film 125A and also improve the corrosion resistance of the insulating layer 127.

[0339] As described above, the insulating layer 127 preferably has a tapered shape with a taper angle θ1 on the side surface in a cross-sectional view of the display device. Also, the insulating layer 127 preferably has a convex curved top surface in a cross-sectional view of the display device.

[0340] Here, it is preferable that the insulating layer 127 be shrunk so that one end overlaps the pixel electrode 111a and the other end overlaps the pixel electrode 111b. Alternatively, it is preferable that the insulating layer 127 be shrunk so that one end overlaps the pixel electrode 111b and the other end overlaps the pixel electrode 111c. Alternatively, it is preferable that the insulating layer 127 be shrunk so that one end overlaps the pixel electrode 111c and the other end overlaps the pixel electrode 111a. By using such a structure, the end of the insulating layer 127 can be formed on a substantially flat region of the EL layer 113a (EL layer 113b). Therefore, it is relatively easy to form the tapered shape of the insulating layer 127 by processing as described above.

[0341] Note that if the side surface of the insulating layer 127 can be processed into a tapered shape only by the heat treatment shown in FIG. 11C, the exposure shown in FIG. 11B may not be performed.

[0342] Furthermore, it is preferable to further perform heat treatment after processing the side surfaces of the insulating layer 127 into a tapered shape. The heat treatment can remove water contained in the EL layer 113, water adsorbed to the surface of the EL layer, and the like. For example, the 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 80° C. to 230° C., preferably 80° C. to 200° C., and more preferably 80° C. to 100° C. The reduced-pressure atmosphere is preferable because dehydration can be performed at a lower temperature.

[0343] Etching may be performed to adjust the height of the surface of the insulating layer 127. The insulating layer 127 may be processed by ashing using oxygen plasma, for example.

[0344] 12A , the light-shielding film 135A and the insulating film 125A are processed. The mask layers 118a, 118b, and 118c are also processed. As a result, the EL layers 113a, 113b, and 113c and the conductive layer 123 are exposed.

[0345] The light-shielding film 135A, the insulating film 125A, and the mask layer 118 can be processed in separate steps, specifically under separate conditions. For example, the light-shielding film 135A can be processed by etching, then the insulating film 125A can be processed by etching, and then the mask layer 118 can be processed by etching. Alternatively, the light-shielding film 135A can be processed by etching, and then the insulating film 125A and the mask layer 118 can be processed by etching. That is, the insulating film 125A and the mask layer 118 can be processed in the same step, specifically under the same conditions. For example, if the mask layer 118 and the insulating film 125A are formed using the same material, they can be processed in the same step. Note that if the light-shielding film 135A, the insulating film 125A, and the mask layer 118 can be processed under the same conditions, the light-shielding film 135A, the insulating film 125A, and the mask layer 118 can all be processed in the same step.

[0346] The light-shielding film 135A can be processed by, for example, dry etching.６ , C.F. ４ , HBr, Cl ２ , BCl ３ , H ２ , O ２ It is preferable to use a gas containing one or more of the noble gases such as Ar and He as the etching gas.

[0347] 12A , regions of the light-shielding film 135A and the insulating film 125A that overlap with the insulating layer 127 remain as the light-shielding layer 135 and the insulating layer 125. Furthermore, regions of the mask layer 118a, the mask layer 118b, and the mask layer 118c that overlap with the insulating layer 127 also remain.

[0348] For example, the insulating layer 125 is provided so as to cover part of the side surface and the top surface of the EL layer 113. This prevents films to be formed later from coming into contact with the side surfaces of these layers, thereby preventing the light-emitting element from shorting out. In addition, damage to the EL layer 113 in a later process can be prevented.

[0349] The mask layer 118 can be processed by a method similar to that which can be used to process the mask layer 119. The insulating film 125A can also be processed by a method similar to that which can be used to process the mask layer 118 or the mask layer 119.

[0350] Next, as shown in FIG. 12B, the common layer 114 is formed over the EL layer 113 and the insulating layer 127.

[0351] 12B shows an example in which the common layer 114 is not provided in the connection portion 140. As shown in Fig. 12B, the end of the common layer 114 on the connection portion 140 side is preferably located more inward than the connection portion 140. For example, when forming the common layer 114, it is preferable to use a mask (also called an area mask or a rough metal mask) for defining the film formation area.

[0352] Furthermore, depending on the level of conductivity of the common layer 114, the common layer 114 may be provided in the connection portion 140. By using such a configuration, it is possible to form the connection portion 140 having a structure in which the conductive layer 123 is electrically connected to the common electrode 115 via the common layer 114, as shown in FIG.

[0353] The materials that can be used for the common layer 114 are as described above. The common 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 common layer 114 may also be formed using a premixed material.

[0354] If the common layer 114 has high conductivity, the side surface of the pixel electrode 111 or the side surface of the EL layer 113 may be in contact with the common layer 114, which may cause a short circuit in the light-emitting element. However, in the display device of one embodiment of the present invention, the insulating layer 125, the light-blocking layer 135, and the insulating layer 127 cover the side surfaces of the EL layer 113, and the EL layer 113 covers the side surfaces of the pixel electrode 111. This prevents the highly conductive common layer 114 from being in contact with the side surfaces of these layers, thereby preventing a short circuit in the light-emitting element. This improves the reliability of the light-emitting element.

[0355] Furthermore, since the space between the EL layer 113a and the EL layer 113b and the space between the EL layer 113b and the EL layer 113c are filled with the insulating layer 125, the light-shielding layer 135, and the insulating layer 127, the surface on which the common layer 114 is formed has smaller steps and is flatter than when the insulating layer 125, the light-shielding layer 135, and the insulating layer 127 are not provided. This improves the coverage of the common layer 114.

[0356] 12C, a common electrode 115 is formed on the common layer 114 and the conductive layer 123. This brings the conductive layer 123 and the common electrode 115 into direct contact with each other, thereby electrically connecting them. With this configuration, it is possible to form a connection portion 140 shown in FIG. 2B2, in which the upper surface of the conductive layer 123 and the common electrode 115 are in contact with each other.

[0357] A mask (also referred to as an area mask or a rough metal mask) for defining a film formation area may be used when forming the common electrode 115. Alternatively, the mask may not be used for forming the common electrode 115, and after the film that becomes the common electrode 115 is formed, the film that becomes the common electrode 115 may be processed using, for example, a resist mask.

[0358] 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.

[0359] Thereafter, a protective layer 131 is formed on the common electrode 115. Furthermore, by bonding a substrate 120 onto the protective layer 131 using an adhesive layer 122, the display device 100 shown in FIGS.

[0360] The materials and film formation methods that can be used for the protective layer 131 are as described above. Examples of the film formation method for the protective layer 131 include a vacuum deposition method, a sputtering method, a CVD method, and an ALD method. The protective layer 131 may have a single-layer structure or a multilayer structure.

[0361] In a display device according to one embodiment of the present invention, the EL layer is provided in an island shape for each subpixel, thereby suppressing leakage current between the subpixels. Furthermore, as described above, by providing a stacked structure of an inorganic insulating layer and an organic insulating layer between each light-emitting element, it is possible to prevent discontinuities and locally thin areas from forming in the common layer and common electrode on the stacked structure. Therefore, it is possible to suppress connection defects caused by discontinuities and increases in electrical resistance caused by locally thin areas in the common layer and common electrode. This allows the display device according to one embodiment of the present invention to achieve both high resolution and high display quality.

[0362] [Example 2 of Manufacturing Method of Display Device] An example of a manufacturing method of the display device shown in Fig. 4A and Fig. 4B2 etc. will be described with reference to Fig. 13A to Fig. 17B. Fig. 13A to Fig. 17B show cross-sectional views taken along dashed lines X1-X2 and Y1-Y2 in Fig. 1 side by side. The following mainly describes steps different from those shown in Fig. 13A to Fig. 17B.

[0363] First, the same steps as those shown in Figures 8A to 11C are carried out, thereby fabricating the structure shown in Figure 13A.

[0364] 13B, an etching process is performed using the insulating layer 127C as a mask to process the light-shielding film 135A, thereby forming the light-shielding layer 135. As described above, the light-shielding film 135A can be processed by, for example, dry etching.

[0365] Next, as shown in Fig. 14A, an etching process is performed using insulating layer 127C as a mask to process insulating film 125A, thereby thinning mask layers 118a, 118b, and 118c. As a result, insulating layer 125 is formed under insulating layer 127C. Fig. 14B is an enlarged cross-sectional view of the EL layer 113b and insulating layer 127C in Fig. 14A.

[0366] The etching process can be performed by dry etching or wet etching. It is preferable to form the insulating film 125A using the same material and method as the mask films 118A, 118B, and 118C, because this allows for the removal of a portion of the insulating film 125A and the thinning of the mask films 118A, 118B, and 118C to be performed simultaneously by the etching process. Furthermore, if the light-shielding film 135A, the insulating film 125A, and the mask layer 118 can be processed under the same etching conditions, the light-shielding film 135A, the insulating film 125A, and the mask layer 118 can all be processed in the same process.

[0367] For example, as shown in FIG. 14B, by performing dry etching using insulating layer 127C, which has tapered side surfaces, as a mask, it is possible to relatively easily make the side surfaces of insulating layer 125 and the upper end portions of the side surfaces of mask layers 118a, 118b, and 118c tapered.

[0368] When dry etching is performed, it is preferable to use a chlorine-based gas. ２ , BCl ３ , SiCl ４ , and CCl ４ The chlorine-based gas may be added with oxygen gas, hydrogen gas, helium gas, argon gas, or the like, either alone or in combination of two or more gases. Dry etching can be used to form thin regions of the mask layers 118 a, 118 b, and 118 c with good in-plane uniformity.

[0369] The dry etching apparatus may be a dry etching apparatus having a high-density plasma source. The dry etching apparatus having a high-density plasma source may be, for example, an inductively coupled plasma (ICP) etching apparatus. Alternatively, a capacitively coupled plasma (CCP) etching apparatus having parallel-plate electrodes may be used. The capacitively coupled plasma etching apparatus having parallel-plate electrodes may be configured to apply a high-frequency voltage to one of the parallel-plate electrodes. Alternatively, it may be configured to apply a plurality of different high-frequency voltages to one of the parallel-plate electrodes. Alternatively, it may be configured to apply a high-frequency voltage of the same frequency to each of the parallel-plate electrodes. Alternatively, it may be configured to apply high-frequency voltages of different frequencies to each of the parallel-plate electrodes.

[0370] Furthermore, when dry etching is performed, by-products produced by the dry etching may be deposited on the upper surface and side surfaces of the insulating layer 127C, etc. Therefore, components contained in the etching gas, components contained in the light-shielding film 135A, components contained in the insulating film 125A, and components contained in the mask layers 118a, 118b, and 118c may be contained in the insulating layer 127C.

[0371] When the etching process is performed by wet etching, it can be performed by using, for example, a method similar to the wet etching method shown in FIG. 16B, which will be described later.

[0372] 14B , in this etching process, the mask layers 118 a, 118 b, and 118 c are not completely removed, and the etching process is stopped when the film thicknesses of the mask layers 118 a, 118 b, and 118 c are reduced. In this way, by leaving the mask layers 118 a, 118 b, and 118 c on the EL layers 113 a, 113 b, and 113 c, respectively, it is possible to prevent the EL layers 113 a, 113 b, and 113 c from being damaged in subsequent processing steps.

[0373] 14A, for example, the mask layers 118a, 118b, and 118c are configured to have thin thicknesses, but the present invention is not limited to this. For example, depending on the thicknesses of the mask layers 118a, 118b, and 118c, the etching process may be stopped before the insulating film 125A is processed into the insulating layer 125. Furthermore, if the insulating film 125A is formed using the same material and method as the mask layers 118a, 118b, and 118c, the boundaries between the insulating film 125A and the mask layers 118a, 118b, and 118c may become unclear, making it difficult to determine whether the insulating layer 125 has been formed.

[0374] 15A and 15B, plasma treatment is performed to reduce the size of the insulating layer 127C, thereby forming the insulating layer 127. The plasma treatment can be performed using the dry etching apparatus described above. In this case, the plasma treatment can be performed in an oxygen atmosphere without applying a bias voltage. FIG. 15B is an enlarged cross-sectional view of the EL layer 113b and the insulating layer 127 in FIG. 15A.

[0375] 15B , the plasma treatment causes the side edge of the insulating layer 127 to recede, exposing the upper surface of the light-shielding layer 135. The insulating layer 125 is provided so as to overlap the exposed upper surface of the light-shielding layer 135. This makes it possible to prevent side etching from progressing too deeply below the insulating layer 127, for example, when etching the insulating layer 125 in a subsequent step.

[0376] Furthermore, the height of the insulating layer 127 can be adjusted by shrinking the insulating layer 127C through the plasma treatment.

[0377] 5B , the insulating layer 127 has a tapered side with a taper angle θ2, and the upper surface of the insulating layer 127 has a convex curved shape in a cross-sectional view of the display device. By forming the insulating layer 127 in this shape, the common layer 114 and the common electrode 115 can be formed with good coverage over the entire insulating layer 127.

[0378] 16A, an etching process is performed using the insulating layer 127 as a mask to process the light-shielding film 135A, thereby forming the light-shielding layer 135. This etching process can be performed under the same conditions as those for processing the light-shielding film 135A performed in the step shown in FIG. 13B, but it is preferable to use etching conditions that provide a high selectivity with respect to the insulating layer 125. For example, SF ６ A gas containing the above can be used as the etching gas.

[0379] 16B and 16C , an etching process is performed using insulating layer 127 as a mask to process mask layers 118a, 118b, and 118c, and insulating layer 125. As a result, openings are formed in mask layers 118a, 118b, and 118c, respectively, exposing the top surfaces of EL layers 113a, 113b, and 113c, and conductive layer 123. Fig. 16C is an enlarged cross-sectional view of the vicinity of EL layer 113b and insulating layer 127 in Fig. 16B .

[0380] The etching process is preferably performed by wet etching. Compared to dry etching, wet etching can reduce damage to the EL layers 113a, 113b, and 113c. Wet etching can be performed using, for example, an alkaline solution. When using an alkaline solution, a tetramethylammonium hydroxide (TMAH) solution is preferably used. In this case, wet etching can be performed using a puddle method. Note that if the insulating film 125A is formed using the same material and method as the mask films 118A, 118B, and 118C, portions of the mask films 118A, 118B, 118C, and the insulating layer 125 can be removed simultaneously by the etching process, which is preferable. Furthermore, if the light-shielding layer 135, the insulating layer 125, and the mask layer 118 can be processed under the same etching conditions, the light-shielding layer 135, the insulating layer 125, and the mask layer 118 can all be processed in the same process.

[0381] 16C , protrusions 116 are formed on the mask layer 118b and the insulating layer 125 above the EL layer 113b and the pixel electrode 111b. In a cross-sectional view, the protrusions 116 are located outside the insulating layer 127. Although not shown in the enlarged cross-sectional view, protrusions 116 are also formed on the EL layer 113a and the pixel electrode 111a, the EL layer 113c and the pixel electrode 111c, and the conductive layer 123.

[0382] 5B , the protrusion 116 preferably has a tapered shape with a taper angle θ3 on the side surface in a cross-sectional view of the display device. By forming the protrusion 116 in such a forward tapered shape, the EL layer 113 can be formed with good coverage on the common layer 114 and the common electrode 115 provided on the protrusion 116 without, for example, causing a step discontinuity.

[0383] As shown in FIG. 5B, the insulating layer 125 has a portion in the protruding portion 116 that is thinner than the portion overlapping with the insulating layer 127, that is, a countersunk portion 133.

[0384] As described above, by providing the insulating layer 127, the insulating layer 125, the mask layer 118a, the mask layer 118b, and the mask layer 118c, it is possible to prevent connection defects caused by discontinuities in the common layer 114 and the common electrode 115 between the light-emitting elements and an increase in electrical resistance caused by locally thin portions of the film thickness. As a result, the display device according to one embodiment of the present invention can be a display device with high display quality.

[0385] 17A, a common layer 114 is formed over the EL layer 113 and the insulating layer 127. The common layer 114 can be formed by a method similar to the method shown in FIG.

[0386] 17A shows an example in which the common layer 114 is not provided in the connection portion 140. As described above, it is preferable that the end of the common layer 114 on the connection portion 140 side be located more inward than the connection portion 140.

[0387] Furthermore, as described above, depending on the level of conductivity of the common layer 114, the common layer 114 may be provided in the connection portion 140. By using such a configuration, it is possible to form the connection portion 140 having a structure in which the conductive layer 123 is electrically connected to the common electrode 115 via the common layer 114, as shown in FIG.

[0388] 17B, ​​a common electrode 115 is formed on the common layer 114 and the conductive layer 123. As a result, the conductive layer 123 and the common electrode 115 are in direct contact with each other, thereby electrically connecting them. With this configuration, it is possible to form a connection portion 140 shown in FIG. 4B2, in which the upper surface of the conductive layer 123 and the common electrode 115 are in contact with each other. The common electrode 115 can be formed by a method similar to the method shown in FIG. 12C.

[0389] Thereafter, a protective layer 131 is formed on the common electrode 115. Furthermore, by bonding the substrate 120 onto the protective layer 131 using an adhesive layer 122, the display device 100 having the configuration shown in Fig. 4A and Fig. 4B2 can be manufactured.

[0390] [Pixel Layout] The following mainly describes pixel layouts that differ from those in Fig. 1. There are no particular limitations on the arrangement of light-emitting elements (sub-pixels), and various methods can be applied.

[0391] 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, shapes of these polygons 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 element.

[0392] An S-stripe arrangement is applied to the pixel 150 shown in Fig. 18A. The pixel 150 shown in Fig. 18A is composed of subpixels 110a, 110b, and 110c. For example, the subpixel 110a can exhibit blue, the subpixel 110b can exhibit red, and the subpixel 110c can exhibit green.

[0393] The pixel 150 shown in FIG. 18B 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 more reliable the light-emitting element, the smaller the size of the subpixel. For example, the subpixel 110a can emit green, the subpixel 110b can emit red, and the subpixel 110c can emit blue.

[0394] The pixels 124a and 124b shown in Fig. 18C are arranged in a Pentile arrangement. Fig. 18C shows an example in which the pixel 124a having the subpixels 110a and 110b and the pixel 124b having the subpixels 110b and 110c are arranged alternately. For example, the subpixel 110a can exhibit red, the subpixel 110b can exhibit green, and the subpixel 110c can exhibit blue.

[0395] 18D and 18E are arranged in a delta configuration. The pixel 124a has two subpixels 110 (subpixel 110a and subpixel 110b) in the upper row (first row) and one subpixel 110 (subpixel 110c) in the lower row (second row). The pixel 124b has one subpixel 110 (subpixel 110c) in the upper row (first row) and two subpixels 110 (subpixel 110a and subpixel 110b) in the lower row (second row). For example, the subpixel 110a can exhibit red, the subpixel 110b can exhibit green, and the subpixel 110c can exhibit blue.

[0396] FIG. 18D shows an example in which each subpixel has a substantially rectangular top surface shape with rounded corners, and FIG. 18E shows an example in which each subpixel has a circular top surface shape.

[0397] 18F shows an example in which the subpixels 110 of each color are arranged in a zigzag pattern. Specifically, when viewed from above, the positions of the upper edges of two subpixels 110 arranged in the column direction (e.g., subpixels 110a and 110b, or subpixels 110b and 110c) are misaligned. For example, the subpixel 110a can exhibit red, the subpixel 110b can exhibit green, and the subpixel 110c can exhibit blue.

[0398] In photolithography, the finer the pattern to be processed, the more the influence of light diffraction becomes significant, which impairs the fidelity of the photomask pattern when transferred by exposure, making it difficult to process the resist mask into the desired shape. Therefore, even if the photomask pattern is rectangular, a pattern with rounded corners is likely to be formed. Therefore, the top surface shape of the light-emitting element may become a polygon with rounded corners, an ellipse, a circle, or the like.

[0399] 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 deviates 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.

[0400] In order to form the top surface of the EL layer into a desired shape, a technique for correcting a mask pattern in advance (OPC (Optical Proximity Correction) technique) may be used so that the design pattern and the transfer pattern coincide with each other. Specifically, in the OPC technique, a correction pattern is added to, for example, the corners of figures on the mask pattern.

[0401] This concludes the description of the pixel layout.

[0402] This embodiment mode can be implemented by appropriately combining at least a part thereof with other embodiment modes described in this specification.

[0403] Embodiment 2 In this embodiment, a display device according to one embodiment of the present invention will be described with reference to drawings.

[0404] The display device of this embodiment can be a high-resolution display device. For example, the display device of one embodiment of the present invention can be used for a display portion of a wristwatch-type or bracelet-type information terminal (wearable device), a VR device such as a head-mounted display, or a head-mountable wearable device such as a glasses-type AR device.

[0405] 19A shows a perspective view of a display module 280. The display module 280 includes a display device 200A and an FPC 290. Note that the display device included in the display module 280 is not limited to the display device 200A, and may be any of display devices 200B to 200F described later.

[0406] 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 an area for displaying an image.

[0407] 19B is a perspective view schematically illustrating the configuration on the substrate 291 side. A circuit portion 282, a pixel circuit portion 283 on the circuit portion 282, and a pixel portion 284 on the pixel circuit portion 283 are stacked on the substrate 291. A terminal portion 285 for connecting to the FPC 290 is provided in a portion of the substrate 291 that does not overlap with the pixel portion 284. The terminal portion 285 and the circuit portion 282 are electrically connected by a wiring portion 286 composed of a plurality of wirings.

[0408] 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. 19B. The pixel 284a has, for example, a red sub-pixel 110a, a green sub-pixel 110b, and a blue sub-pixel 110c.

[0409] The pixel circuit portion 283 has a plurality of pixel circuits 283a arranged periodically. Each pixel circuit 283a is a circuit that controls the light emission of three light-emitting elements 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 element. For example, the pixel circuit 283a may be configured to have at least one selection transistor, one current control transistor (drive transistor), and a capacitor for each light-emitting element. In this case, a gate signal is input to the gate of the selection transistor, and a video signal is input to either the source or the drain. This realizes an active matrix display device.

[0410] 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 signal 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. Furthermore, a transistor provided in the circuit portion 282 may constitute a part of the pixel circuit 283a. That is, the pixel circuit 283a may be composed of a transistor included in the pixel circuit portion 283 and a transistor included in the circuit portion 282.

[0411] The FPC 290 functions as wiring for supplying a video signal, a power supply potential, and the like from the outside to the circuit portion 282. An IC may be mounted on the FPC 290.

[0412] The display module 280 can be configured such that one or both of the pixel circuit unit 283 and the circuit unit 282 are stacked below the pixel unit 284, thereby enabling the aperture ratio (effective display area ratio) of the display unit 281 to be extremely high. For example, the aperture ratio of the display unit 281 can be 40% or more and less than 100%, preferably 50% or more and 95% or less, and more preferably 60% or more and 95% or less. Furthermore, the pixels 284a can be arranged at an extremely high density, enabling the resolution of the display unit 281 to be extremely high. For example, it is preferable that the pixels 284a be arranged in the display unit 281 at a resolution of 2000 ppi or more, preferably 3000 ppi or more, more preferably 5000 ppi or more, and even more preferably 6000 ppi or more, and 20000 ppi or less, or 30000 ppi or less.

[0413] Because such a display module 280 has extremely high resolution, it can be suitably used in VR devices such as head-mounted displays, or in glasses-type AR devices. For example, even in a configuration in which the display unit of the display module 280 is viewed through lenses, the display module 280 has an extremely high-resolution display unit 281, so even if the display unit is enlarged with lenses, the pixels are not visible, allowing for a highly immersive display. Furthermore, the display module 280 is not limited to this, and can be suitably used in electronic devices with relatively small display units. For example, it can be suitably used in the display unit of a wearable electronic device such as a wristwatch.

[0414] Display Device 200A The display device 200A shown in FIG. 20 includes a substrate 301, a light-emitting element 130a, a light-emitting element 130b, and a light-emitting element 130c, a capacitor 240, and a transistor 310.

[0415] Substrate 301 corresponds to substrate 291 in FIGS. 19A and 19B.

[0416] 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 a source or drain. The insulating layer 314 is provided to cover a side surface of the conductive layer 311.

[0417] An element isolation layer 315 is provided between two adjacent transistors 310 so as to be embedded in the substrate 301 .

[0418] In addition, an insulating layer 261 is provided to cover the transistor 310 , and a capacitor 240 is provided over the insulating layer 261 .

[0419] The capacitor 240 has a conductive layer 241, a conductive layer 245, and an insulating layer 243 located therebetween. The conductive layer 241 functions as one electrode of the capacitor 240, the conductive layer 245 functions as the other electrode of the capacitor 240, and the insulating layer 243 functions as a dielectric of the capacitor 240.

[0420] 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 the 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.

[0421] An insulating layer 255a is provided to cover the capacitor 240, an insulating layer 255b is provided over the insulating layer 255a, and an insulating layer 255c is provided over the insulating layer 255b.

[0422] The light emitting elements 130a, 130b, and 130c are provided on the insulating layer 255c. The light emitting elements 130a, 130b, and 130c may have the same configuration as that of the light emitting element 130a, 130b, and 130c described in the first embodiment.

[0423] In the display device 200A, since the light-emitting elements 130 are individually manufactured for each emitted color, there is little change in chromaticity between light emitted at low luminance and light emitted at high luminance. Furthermore, since the EL layers 113a, 113b, and 113c are spaced apart from one another, crosstalk between adjacent subpixels can be suppressed even in a high-resolution display device. Therefore, a high-resolution and high-quality display device can be realized.

[0424] A mask layer 118 , an insulating layer 125 , a light-shielding layer 135 , and an insulating layer 127 are provided between adjacent light-emitting elements 130 .

[0425] The pixel electrode 111a, the pixel electrode 111b, and the pixel electrode 111c of the light-emitting element 130 are electrically connected to one of the source and drain of the transistor 310 via a plug 256 embedded in the insulating layer 243, the insulating layer 255a, the insulating layer 255b, and the insulating layer 255c, 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 255c 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.

[0426] A protective layer 131 is provided on the light emitting element 130. A substrate 120 is attached to the protective layer 131 with an adhesive layer 122.

[0427] Between two adjacent pixel electrodes 111, there is no insulating layer covering the upper surface end of the pixel electrode 111. Therefore, the distance between adjacent light-emitting elements 130 can be made extremely short, and therefore a high-definition or high-resolution display device can be obtained.

[0428] 21 has a configuration in which a transistor 310A and a transistor 310B, each having a channel formed in a semiconductor substrate, are stacked. Note that in the following description of the display device, descriptions of parts that are the same as those of the display device described above may be omitted.

[0429] The display device 200B has a configuration in which a substrate 301B on which a transistor 310B, a capacitor 240, and a light-emitting element 130 are provided and a substrate 301A on which a transistor 310A is provided are bonded together.

[0430] Here, an insulating layer 345 is provided on the lower surface of the substrate 301B, and an insulating layer 346 is provided on the insulating layer 261 provided on the substrate 301A. The insulating layers 345 and 346 function as protective layers and can suppress the diffusion of impurities into the substrates 301B and 301A. The insulating layers 345 and 346 can be made of an inorganic insulating film that can be used for the protective layer 131.

[0431] The substrate 301B is provided with a plug 343 that penetrates the substrate 301B and an insulating layer 345. Here, it is preferable to provide an insulating layer 344 that covers the side surface of the plug 343 and functions as a protective layer.

[0432] Furthermore, in the substrate 301B, a conductive layer 342 is provided below the insulating layer 345. The conductive layer 342 is embedded in the insulating layer 335, and the lower surfaces of the conductive layer 342 and the insulating layer 335 are flattened. The conductive layer 342 is electrically connected to a plug 343.

[0433] Meanwhile, between the substrates 301A and 301B, a conductive layer 341 is provided on the insulating layer 346. The conductive layer 341 is embedded in the insulating layer 336, and the upper surfaces of the conductive layer 341 and the insulating layer 336 are flattened.

[0434] It is preferable to use the same conductive material for the conductive layers 341 and 342. For example, a metal film containing an element selected from Al, Cr, Cu, Ta, Ti, Mo, and W, or a metal nitride film containing the above elements (titanium nitride film, molybdenum nitride film, or tungsten nitride film) can be used. In particular, it is preferable to use copper for the conductive layers 341 and 342. This allows the use of Cu-Cu (copper-copper) direct bonding technology (technology that achieves electrical conductivity by connecting Cu (copper) pads together).

[0435] [Display Device 200C] A display device 200C shown in FIG. 22 has a configuration in which a conductive layer 341 and a conductive layer 342 are joined via a bump 347.

[0436] 22 , 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), or tin (Sn). Alternatively, for example, solder may be used as the bump 347. An adhesive layer 348 may be provided between the insulating layer 345 and the insulating layer 346. When the bump 347 is provided, the insulating layer 335 and the insulating layer 336 may not be provided.

[0437] [Display Device 200D] A display device 200D shown in FIG. 23 differs from the display device 200A mainly in the configuration of the transistors.

[0438] 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.

[0439] 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 .

[0440] Substrate 331 corresponds to substrate 291 in FIGS. 19A and 19B.

[0441] An insulating layer 332 is provided over a substrate 331. The insulating layer 332 functions as a barrier layer that prevents impurities such as water or hydrogen from diffusing from the substrate 331 to the transistor 320 and prevents oxygen from being released from the semiconductor layer 321 toward the insulating layer 332. The insulating layer 332 can be, for example, a film through which hydrogen or oxygen is less likely to diffuse than a silicon oxide film, such as an aluminum oxide film, a hafnium oxide film, or a silicon nitride film.

[0442] 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.

[0443] The semiconductor layer 321 is provided over the insulating layer 326. The semiconductor layer 321 preferably includes a metal oxide film exhibiting semiconductor characteristics. 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.

[0444] 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 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.

[0445] An opening reaching the semiconductor layer 321 is provided in the insulating layer 328 and the insulating layer 264. An insulating layer 323 in contact with the top surface of the semiconductor layer 321 and a conductive layer 324 are buried in the opening. The conductive layer 324 functions as a second gate electrode, and the insulating layer 323 functions as a second gate insulating layer.

[0446] The top surfaces of the conductive layer 324, the insulating layer 323, and the insulating layer 264 are planarized so that their heights are the same or approximately the same, and insulating layers 329 and 265 are provided to cover them.

[0447] 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 to the transistor 320. The insulating layer 329 can be formed using an insulating film similar to the insulating layers 328 and 332.

[0448] 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, the insulating layer 264, and the insulating layer 328. Here, the plug 274 preferably includes a conductive layer 274a covering the side surfaces of the openings of the insulating layer 265, the insulating layer 329, the insulating layer 264, and the insulating layer 328 and part of the top surface of the conductive layer 325, and a conductive layer 274b in contact with the top surface of the conductive layer 274a. In this case, the conductive layer 274a is preferably made of a conductive material through which hydrogen and oxygen do not easily diffuse.

[0449] [Display Device 200E] A display device 200E illustrated in FIG. 24 has a stacked structure of a transistor 320A and a transistor 320B each including an oxide semiconductor as a semiconductor in which a channel is formed.

[0450] The transistor 320A, the transistor 320B, and the peripheral configuration thereof can be adapted from the display device 200D.

[0451] Although two transistors including an oxide semiconductor are stacked here, the present invention is not limited to this structure, and for example, three or more transistors may be stacked.

[0452] [Display Device 200F] A display device 200F illustrated in FIG. 25 has a stacked structure of a transistor 310 in which a channel is formed in a substrate 301 and a transistor 320 in which a channel is formed and a semiconductor layer containing metal oxide.

[0453] An insulating layer 261 is provided to cover the transistor 310, and a conductive layer 251 is provided over the insulating layer 261. An insulating layer 262 is provided to cover the conductive layer 251, and a conductive layer 252 is provided over the insulating layer 262. The conductive layers 251 and 252 each function as wirings. An insulating layer 263 and an insulating layer 332 are provided to cover the conductive layer 252, and the transistor 320 is provided over the insulating layer 332. An insulating layer 265 is provided to cover the transistor 320, and a capacitor 240 is provided over the insulating layer 265. The capacitor 240 and the transistor 320 are electrically connected by a plug 274.

[0454] The transistor 320 can be used as a transistor that forms a pixel circuit. The transistor 310 can be used as a transistor that forms a pixel circuit or a driver circuit (gate line driver circuit, signal line driver circuit) that drives the pixel circuit. The transistors 310 and 320 can be used as transistors that form various circuits such as an arithmetic circuit or a memory circuit.

[0455] By using such a configuration, not only a pixel circuit but also, for example, a driving circuit can be formed directly below the light-emitting element 130, which makes it possible to reduce the size of the display device compared to when the driving circuit is provided around the periphery of the display area.

[0456] This embodiment mode can be implemented by appropriately combining at least a part thereof with other embodiment modes described in this specification.

[0457] Embodiment 3 In this embodiment, a structural example of a display device according to one embodiment of the present invention will be described.

[0458] The display device of this embodiment can be used in 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 display units of digital cameras, digital video cameras, digital photo frames, mobile phones, portable game machines, smartphones, wristwatch-type terminals, tablet terminals, personal digital assistants, and sound reproduction devices.

[0459] [Display Device 400] FIG. 26 shows a perspective view of display device 400, and FIG. 27A shows a cross-sectional view of display device 400.

[0460] The display device 400 has a configuration in which the substrate 120 and the substrate 451 are bonded together. In Fig. 26, the substrate 120 is clearly indicated by a dashed line.

[0461] The display device 400 includes a display portion 462, a circuit 464, wiring 465, and the like. Fig. 26 shows an example in which an IC 473 and an FPC 472 are mounted on the display device 400. As described above, a display device having a connector such as an FPC attached to a substrate or a display device having an IC mounted on the substrate is called a display module. Therefore, the configuration shown in Fig. 26 can also be called a display module having the display device 400, an IC (integrated circuit), and an FPC.

[0462] The circuit 464 can be, for example, a scanning line driver circuit.

[0463] The wiring 465 has a function of supplying signals and power to the display portion 462 and the circuit 464. The signals and power are input to the wiring 465 from the outside via the FPC 472 or input to the wiring 465 from the IC 473.

[0464] 26 shows an example in which an IC 473 is provided on a substrate 451 by a COG method, a COF (chip on film) method, or the like. The IC 473 can be, for example, an IC having a scanning line driver circuit or a signal line driver circuit. Note that the display device 400 and the display module may not necessarily include an IC. Alternatively, the IC may be mounted on an FPC by, for example, a COF method.

[0465] 27A shows an example of a cross section of the display device 400, when a part of a region including the FPC 472, a part of the circuit 464, a part of the display unit 462, and a part of a region including the connection unit 140 are cut away. In FIG. 27A, an example of a cross section is shown, when a region of the display unit 462, in particular, a region including the light-emitting element 130b that emits green light and the light-emitting element 130c that emits blue light is cut away.

[0466] 27A includes a transistor 202, a transistor 210, a light-emitting element 130b, a light-emitting element 130c, and the like between a substrate 451 and a substrate 120. Note that the display device 400 also includes, for example, a light-emitting element 130a in addition to the elements shown in FIG.

[0467] The light-emitting element described in Embodiment 1 can be applied to the light-emitting element 130 .

[0468] Here, when a pixel of a display device has three types of sub-pixels having light-emitting elements that emit different colors, the three sub-pixels include sub-pixels of three colors of red (R), green (G), and blue (B), or sub-pixels of three colors of yellow (Y), cyan (C), and magenta (M), etc. When a pixel of a display device has four sub-pixels, the four sub-pixels include sub-pixels of four colors of R, G, B, and white (W), or sub-pixels of four colors of R, G, B, and Y, etc.

[0469] The substrate 120 and the protective layer 131 are bonded together via an adhesive layer 122. The adhesive layer 122 is provided so as to overlap the light emitting element 130, and a solid sealing structure is applied to the display device 400.

[0470] The light-emitting element 130 includes a conductive layer 411a and a conductive layer 411b as pixel electrodes. The conductive layer 411b has a property of reflecting visible light and can function as a reflective electrode.

[0471] The conductive layer 411a is connected to a conductive layer 222b of the transistor 210 through an opening provided in the insulating layer 214. The transistor 210 has a function of controlling the driving of the light-emitting element .

[0472] An EL layer 113 is provided covering the pixel electrode. A mask layer 118 is provided so as to cover a portion of the upper surface of the EL layer 113, and an insulating layer 125 is provided so as to cover the upper surface of the mask layer 118 and the side surfaces of the EL layer 113. A light-shielding layer 135 is provided on the insulating layer 125, and an insulating layer 127 is provided on the light-shielding layer 135. The insulating layer 127 is provided so as to fill the recesses in the light-shielding layer 135. A common layer 114 is provided on the EL layer 113 and on the insulating layer 127. A common electrode 115 is provided on the common layer 114, and a protective layer 131 is provided on the common electrode 115.

[0473] Light emitted from the light emitting element 130 is emitted toward the substrate 120. The substrate 120 is preferably made of a material that is highly transparent to visible light.

[0474] The transistor 202 and the transistor 210 are both formed over a substrate 451. These transistors can be manufactured using the same material and through the same process.

[0475] The substrate 451 and the insulating layer 212 are bonded together by an adhesive layer 455 .

[0476] In a method for manufacturing the display device 400, first, a formation substrate provided with the insulating layer 212, the transistors, the light-emitting elements, and the like is bonded to the substrate 120 with an adhesive layer 122. Then, the formation substrate is peeled off, and a substrate 451 is attached to the exposed surface, so that the components formed on the formation substrate are transferred to the substrate 451. The substrate 451 and the substrate 120 each preferably have flexibility. This can increase the flexibility of the display device 400.

[0477] The insulating layer 212 can be formed using the inorganic insulating film that can be used for the insulating layer 211 and the insulating layer 215 .

[0478] A connection portion 204 is provided in a region of the substrate 451 that does not overlap with the substrate 120. In the connection portion 204, a wiring 465 is electrically connected to an FPC 472 via a conductive layer 466 and a connection layer 242. The conductive layer 466 can be obtained by processing the same conductive film as the pixel electrode. This allows the connection portion 204 and the FPC 472 to be electrically connected via the connection layer 242.

[0479] The transistor 202 and the transistor 210 each include a conductive layer 221 functioning as a gate, an insulating layer 211 functioning as a gate insulating layer, a semiconductor layer 231 including a channel formation region 231i and a pair of low-resistance regions 231n, a conductive layer 222a connected to one of the pair of low-resistance regions 231n, a conductive layer 222b connected to the other of the pair of low-resistance regions 231n, an insulating layer 225 functioning as a gate insulating layer, a conductive layer 223 functioning as a gate, and an insulating layer 215 covering the conductive layer 223. The insulating layer 211 is located between the conductive layer 221 and the channel formation region 231i. The insulating layer 225 is located between the conductive layer 223 and the channel formation region 231i.

[0480] The conductive layer 222a and the conductive layer 222b are each connected to the low-resistance region 231n through an opening provided in the insulating layer 215. One of the conductive layer 222a and the conductive layer 222b functions as a source, and the other functions as a drain.

[0481] 27A shows an example in which the top surface and side surfaces of the semiconductor layer are covered with an insulating layer 225. 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.

[0482] 27B , 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. 27B . In FIG. 27B , 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. Furthermore, an insulating layer 218 may be provided to cover the transistor.

[0483] The structure of the transistor included in the display device of this embodiment is not particularly limited. For example, a planar transistor, a staggered transistor, an inverted staggered transistor, or the like can be used. Furthermore, either a top-gate transistor or a bottom-gate transistor structure may be used. Alternatively, gates may be provided above and below a semiconductor layer in which a channel is formed.

[0484] The transistor 202 and the transistor 210 have a structure in which a semiconductor layer in which a channel is formed is sandwiched between two gates. The two gates may be connected and the same signal may be supplied to drive the transistor. Alternatively, the threshold voltage of the transistor may be controlled by applying a potential for controlling the threshold voltage to one of the two gates and a potential for driving to the other.

[0485] The crystallinity of a semiconductor material used for a semiconductor layer of a transistor is not particularly limited, and any of an amorphous semiconductor, a single crystal semiconductor, and a semiconductor having crystallinity other than a single crystal (a microcrystalline semiconductor, a polycrystalline semiconductor, or a semiconductor having a crystalline region in part) may be used. The use of a single crystal semiconductor or a crystalline semiconductor is preferable because it can suppress deterioration of transistor characteristics.

[0486] A semiconductor layer of the transistor preferably contains a metal oxide. That is, the display device of this embodiment preferably uses a transistor in which a channel formation region is formed using a metal oxide (hereinafter referred to as an OS transistor).

[0487] The band gap of the metal oxide used for the semiconductor layer of the transistor is preferably 2 eV or more, more preferably 2.5 eV or more. Use of a metal oxide with a wide band gap can reduce the off-state current of the OS transistor.

[0488] The metal oxide preferably contains at least indium or zinc, and more preferably contains indium and zinc. For example, the metal oxide preferably contains indium, M (wherein M is one or more selected from gallium, aluminum, yttrium, tin, silicon, boron, copper, vanadium, beryllium, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, magnesium, and cobalt), and zinc.

[0489] Alternatively, the semiconductor layer of the transistor may contain silicon. Examples of silicon include amorphous silicon and crystalline silicon (such as low-temperature polysilicon or single-crystal silicon). In particular, a transistor having low-temperature polysilicon (LTPS) in its semiconductor layer (hereinafter also referred to as an LTPS transistor) can be used. An LTPS transistor has high field-effect mobility and favorable frequency characteristics.

[0490] By using Si 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.

[0491] An OS transistor has significantly higher field-effect mobility than a transistor using amorphous silicon. Furthermore, an OS transistor has significantly lower source-drain leakage current in an off state (hereinafter also referred to as off-state current), and can hold charge accumulated in a capacitor connected in series with the transistor for a long period of time. Furthermore, the use of an OS transistor can reduce the power consumption of a display device.

[0492] The off-state current of the OS transistor per 1 μm of channel width at room temperature is 1 aA (1×10 −１８ A) Below, 1zA (1×10 −２１ A) or less, or 1yA (1 x 10 −２４ Note that the off-state current of a Si transistor per 1 μm of channel width at room temperature can be 1 fA (1×10 −１５ A) More than 1pA (1×10 −１２ Therefore, it can be said that the off-state current of an OS transistor is about 10 orders of magnitude lower than that of a Si transistor.

[0493] Furthermore, to increase the emission luminance of a light-emitting element included in a pixel circuit, it is necessary to increase the amount of current flowing through the light-emitting element. To achieve this, it is necessary to increase the source-drain voltage of a driving transistor included in the pixel circuit. Since an OS transistor has a higher source-drain withstand voltage than a Si transistor, a high voltage can be applied between the source and drain of the OS transistor. Therefore, by using an OS transistor as the driving transistor included in a pixel circuit, it is possible to increase the amount of current flowing through the light-emitting element and increase the emission luminance of the light-emitting element.

[0494] Furthermore, when a transistor operates in a saturation region, an OS transistor can reduce the change in source-drain current with respect to a change in gate-source voltage compared to a Si transistor. Therefore, by using an OS transistor as a driving transistor included in a pixel circuit, the current flowing between the source and drain can be precisely controlled by changing the gate-source voltage, thereby controlling the amount of current flowing to a light-emitting element. This allows for a larger gradation level in the pixel circuit.

[0495] Furthermore, in terms of the saturation characteristics of the current that flows when a transistor operates in a saturation region, an OS transistor can pass a more stable current (saturation current) than a Si transistor, even when the source-drain voltage gradually increases. Therefore, by using an OS transistor as a driving transistor, a stable current can be passed to a light-emitting element, even when the current-voltage characteristics of an EL element vary. In other words, when an OS transistor operates in a saturation region, the source-drain current of the OS transistor remains almost unchanged even when the source-drain voltage increases, thereby stabilizing the light-emitting luminance of the light-emitting element.

[0496] As described above, by using an OS transistor for a driving transistor included in a pixel circuit, it is possible to achieve "suppression of black floating," "increase in light emission luminance," "multiple gradations," "suppression of variations in the characteristics of light-emitting elements," and the like.

[0497] The transistors included in the circuit 464 may have the same structure as or different from the transistors included in the display portion 462. The transistors included in the circuit 464 may all have the same structure or may have two or more types of structures. Similarly, the transistors included in the display portion 462 may all have the same structure or may have two or more types of structures.

[0498] All the transistors included in the display portion 462 may be OS transistors, all the transistors included in the display portion 462 may be Si transistors, or some of the transistors included in the display portion 462 may be OS transistors and the rest may be Si transistors.

[0499] For example, by using both an LTPS transistor and an OS transistor in the display portion 462, a display device with low power consumption and high driving capability can be realized. A structure in which an LTPS transistor and an OS transistor are combined is sometimes referred to as LTPO. Note that, 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 to use an LTPS transistor as a transistor for controlling current.

[0500] For example, one of the transistors included in the display portion 462 functions as a transistor for controlling a current flowing to a light-emitting element and can be called a driving transistor. One of the source and the drain of the driving transistor is electrically connected to a pixel electrode of the light-emitting element. The driving transistor is preferably an LTPS transistor. This can increase the current flowing to the light-emitting element in the pixel circuit.

[0501] On the other hand, another transistor included in the display portion 462 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 signal line. An OS transistor is preferably used as the selection transistor. This allows the gradation of a pixel to be maintained even when the frame frequency is significantly reduced (for example, 1 fps or less). Therefore, power consumption can be reduced by stopping the driver when a still image is displayed.

[0502] As described above, the display device of one embodiment of the present invention can have a high aperture ratio, high definition, high display quality, and low power consumption.

[0503] Note that a display device according to one embodiment of the present invention includes an OS transistor and a light-emitting element with an MML (metal maskless) structure. This structure can significantly reduce leakage current that may flow through the transistor and leakage current that may flow between adjacent light-emitting elements (also referred to as lateral leakage current or side leakage current, etc.). Furthermore, with this structure, when an image is displayed on the display device, a viewer can observe one or more of image clarity, image sharpness, high saturation, and a high contrast ratio. Note that a structure in which leakage current that may flow through the transistor and lateral leakage current between light-emitting elements are extremely low can minimize light leakage that may occur, for example, during black display.

[0504] The configuration of a transistor used in a display device may be appropriately selected depending on the screen size of the display device. For example, when a single-crystal Si transistor is used as the transistor in a display device, the display device can be applied to a screen size having a diagonal size of 0.1 to 3 inches. When an LTPS transistor is used as the transistor in a display device, the display device can be applied to a screen size having a diagonal size of 0.1 to 30 inches, preferably 1 to 30 inches. When an LTPO transistor (a combination of an LTPS transistor and an OS transistor) is used in a display device, the display device can be applied to a screen size having a diagonal size of 0.1 to 50 inches, preferably 1 to 50 inches. When an OS transistor is used as the transistor in a display device, the display device can be applied to a screen size having a diagonal size of 0.1 to 200 inches, preferably 50 to 100 inches.

[0505] It is very difficult to increase the size of a single-crystal Si transistor due to the size of a single-crystal Si substrate. Furthermore, since a laser crystallization apparatus is used in the manufacturing process of an LTPS transistor, it is difficult to accommodate large displays (typically, a screen size exceeding 30 inches in diagonal size). On the other hand, since an OS transistor is not restricted by the use of a laser crystallization apparatus in the manufacturing process or can be manufactured at a relatively low process temperature (typically, 450° C. or lower), it is possible to accommodate display devices with a relatively large area (typically, a diagonal size of 50 inches to 100 inches). Furthermore, LTPO can be applied to display devices with sizes (typically, a diagonal size of 1 inch to 50 inches) that are between those using an LTPS transistor and those using an OS transistor.

[0506] 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.

[0507] It is preferable to use an inorganic insulating film for each of the insulating layers 211, 212, 215, 218, and 225. 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-described inorganic insulating films may be stacked.

[0508] An organic insulating film is suitable for the insulating layer 214 that functions as a planarizing 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, phenol resin, and precursors of these resins.

[0509] Various optical members can be disposed along the inner or outer surface of the substrate 120. Examples of optical members include a light-shielding layer, a polarizing plate, a retardation plate, a light-diffusing layer (e.g., a diffusion film), an anti-reflection layer, a microlens array, and a light-collecting film. In addition, an antistatic film that suppresses the adhesion of dust, a water-repellent film that makes it difficult for dirt to adhere, a hard coat film that suppresses scratches caused by use, or an impact-absorbing layer may be disposed on the outer surface of the substrate 120.

[0510] By providing the protective layer 131 that covers the light emitting element 130, impurities such as water can be prevented from entering the light emitting element 130, and the reliability of the light emitting element can be improved.

[0511] Fig. 27A shows a connection portion 140. The common electrode 115 and the wiring are electrically connected at the connection portion 140. Fig. 27A shows an example in which the same layered structure as that of the pixel electrode is applied to the wiring.

[0512] The substrate 451 and the substrate 120 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 element is extracted. Using a flexible material for the substrate 451 and the substrate 120 can increase the flexibility of the display device. Alternatively, a polarizing plate may be used for the substrate 451 or the substrate 120.

[0513] The substrate 451 and the substrate 120 can each be made of a polyester resin such as polyethylene terephthalate (PET) or polyethylene naphthalate (PEN), a polyacrylonitrile resin, an acrylic resin, a polyimide resin, a polymethyl methacrylate resin, a polycarbonate (PC) resin, a polyethersulfone (PES) resin, a polyamide resin (nylon, aramid, or the like), a polysiloxane resin, a cycloolefin resin, a polystyrene resin, a polyamideimide resin, a polyurethane resin, a polyvinyl chloride resin, a polyvinylidene chloride resin, a polypropylene resin, a polytetrafluoroethylene (PTFE) resin, an ABS resin, or a cellulose nanofiber. One or both of the substrate 451 and the substrate 120 may be made of glass having a thickness sufficient to provide flexibility.

[0514] The adhesive layer can be made of various curable adhesives, such as photo-curable adhesives (e.g., ultraviolet curable), reactive curable adhesives, thermosetting adhesives, or anaerobic adhesives. 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. Materials with low moisture permeability, such as epoxy resin, are particularly preferred. Two-component resins may also be used. Alternatively, an adhesive sheet may be used.

[0515] The connection layer 242 may be an anisotropic conductive film (ACF), an anisotropic conductive paste (ACP), or the like.

[0516] Materials that can be used for the gate, source, and drain of a transistor as well as conductive layers such as various wirings and electrodes that constitute a display device include metals such as aluminum, titanium, chromium, nickel, copper, yttrium, zirconium, molybdenum, silver, tantalum, and tungsten, and alloys containing these metals as main components, etc. Films containing these materials can be used as a single layer or a stacked layer structure.

[0517] 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. Nitrides of metal materials (e.g., titanium nitride) may also be used. When using metal materials or alloy materials (or their nitrides), it is preferable to thin the metal materials to ensure light-transmitting properties. A stacked film of the above materials can also be used as a 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 for conductive layers (conductive layers functioning as pixel electrodes or common electrodes) of light-emitting elements.

[0518] Examples of insulating materials that can be used for each insulating layer include resins such as acrylic resins and epoxy resins, and inorganic insulating materials such as silicon oxide, silicon oxynitride, silicon nitride oxide, silicon nitride, and aluminum oxide.

[0519] This embodiment mode can be implemented by appropriately combining at least a part thereof with other embodiment modes described in this specification.

[0520] Embodiment 4 In this embodiment, a light-emitting element that can be used for a display device that is one embodiment of the present invention will be described.

[0521] Furthermore, light-emitting elements can be broadly classified into a single structure and a tandem structure. A light-emitting element with a single structure has one light-emitting unit between a pair of electrodes, and the light-emitting unit preferably includes one or more light-emitting layers. When two light-emitting layers are used to obtain white light emission, light-emitting layers may be selected such that the emission colors of the two light-emitting layers are complementary to each other. For example, by making the emission color of the first light-emitting layer and the emission color of the second light-emitting layer complementary to each other, a configuration that emits white light as a whole can be obtained. When three or more light-emitting layers are used to obtain white light emission, the emission colors of the three or more light-emitting layers may be combined to enable the light-emitting element to emit white light as a whole.

[0522] A light-emitting element with a tandem structure has multiple light-emitting units between a pair of electrodes. Each light-emitting unit includes one or more light-emitting layers. By using light-emitting layers that emit light of the same color in each light-emitting unit, the luminance per given current can be increased, and the light-emitting element can be made more reliable than a single structure. To obtain white light emission with a tandem structure, light from the light-emitting layers of multiple light-emitting units can be combined to obtain white light emission. The combination of light-emitting colors that can produce white light emission is the same as in the single structure. In a light-emitting element with a tandem structure, it is preferable to provide an intermediate layer, such as a charge-generating layer, between the multiple light-emitting units.

[0523] When comparing a white light-emitting element with a light-emitting element having an SBS structure, the light-emitting element having an SBS structure can consume less power than the white light-emitting element, and the manufacturing process for the white light-emitting element is simpler than that for the light-emitting element having an SBS structure, so the manufacturing cost can be lowered and the manufacturing yield can be increased.

[0524] 28A to 28F are cross-sectional views showing structural examples of a light-emitting element. As shown in FIG. 28A , the light-emitting element has an EL layer 790 between a pair of electrodes (a lower electrode 791 and an upper electrode 792). The EL layer 790 can be composed of multiple layers such as a layer 720, a light-emitting layer 711, and a layer 730. The layer 720 can have, for example, a layer containing a substance with high electron injection properties (electron injection layer) and a layer containing a substance with high electron transport properties (electron transport layer). The light-emitting layer 711 contains, for example, a light-emitting compound. The layer 730 can have, for example, a layer containing a substance with high hole injection properties (hole injection layer) and a layer containing a substance with high hole transport properties (hole transport layer).

[0525] A structure having the layer 720, the light-emitting layer 711, and the layer 730 provided between a pair of electrodes can function as a single light-emitting unit, and the structure of FIG. 28A is referred to as a single structure in this specification.

[0526] 28B includes layers 730-1 and 730-2, a light-emitting layer 711, layers 720-1 and 720-2, and an upper electrode 792 on a lower electrode 791. For example, the lower electrode 791 serves as an anode, and the upper electrode 792 serves as a cathode. In this case, the layer 730-1 functions as a hole injection layer, the layer 730-2 functions as a hole transport layer, the layer 720-1 functions as an electron transport layer, and the layer 720-2 functions as an electron injection layer. On the other hand, when the lower electrode 791 serves as a cathode and the upper electrode 792 serves as an anode, the layer 730-1 functions as an electron injection layer, the layer 730-2 functions as an electron transport layer, the layer 720-1 functions as a hole transport layer, and the layer 720-2 functions as a hole injection layer. This layer structure allows carriers to be efficiently injected into the light-emitting layer 711, thereby increasing the efficiency of carrier recombination within the light-emitting layer 711.

[0527] As shown in FIGS. 28C and 28D, a configuration in which a plurality of light-emitting layers (light-emitting layer 711, light-emitting layer 712, and light-emitting layer 713) are provided between layer 720 and layer 730 is also a variation of the single structure.

[0528] As shown in Figures 28E and 28F, a configuration in which a plurality of light-emitting units (EL layers 790a and 790b) are connected in series via an intermediate layer (charge generating layer) 740 is referred to as a tandem structure in this specification. The tandem structure may also be referred to as a stack structure. Note that the tandem structure makes it possible to obtain a light-emitting element capable of emitting light with high brightness.

[0529] 28C, light-emitting materials that emit light of the same color, or even the same light-emitting material, may be used for the light-emitting layers 711, 712, and 713. Stacking the light-emitting layers can increase the luminance of emitted light.

[0530] Different light-emitting materials may be used for the light-emitting layer 711, the light-emitting layer 712, and the light-emitting layer 713. When the light emitted from the light-emitting layer 711, the light-emitting layer 712, and the light-emitting layer 713 has a complementary color relationship, white light can be obtained. Figure 28D shows an example in which a colored layer 795 that functions as a color filter is provided. When white light passes through the color filter, light of a desired color can be obtained.

[0531] 28E, the light-emitting layer 711 and the light-emitting layer 712 may be made of light-emitting materials that emit light of the same color. Alternatively, the light-emitting layer 711 and the light-emitting layer 712 may be made of light-emitting materials that emit different colors. When the light emitted by the light-emitting layer 711 and the light emitted by the light-emitting layer 712 are complementary colors, white light emission is obtained. FIG. 28F shows an example in which a colored layer 795 is further provided.

[0532] 28C, 28D, 28E, and 28F, the layer 720 and the layer 730 may have a laminated structure consisting of two or more layers, as shown in FIG. 28B.

[0533] 28D, light-emitting layers 711, 712, and 713 may be made of light-emitting materials that emit light of the same color. Similarly, in FIG. 28F, light-emitting layers 711 and 712 may be made of light-emitting materials that emit light of the same color. In this case, by applying a color conversion layer instead of colored layer 795, light of a desired color different from the light-emitting material can be obtained. For example, by using a blue light-emitting material in each light-emitting layer and transmitting blue light through the color conversion layer, light with a wavelength longer than blue (e.g., red or green) can be obtained. A fluorescent material, a phosphorescent material, a quantum dot, or the like can be used as the color conversion layer.

[0534] The light-emitting color of the light-emitting element can be red, green, blue, cyan, magenta, yellow, white, or the like, depending on the material constituting the EL layer 790. Furthermore, the color purity can be further improved by providing the light-emitting element with a microcavity structure.

[0535] A light-emitting element that emits white light may have a structure in which two or more types of light-emitting substances are contained in a light-emitting layer, or two or more light-emitting layers containing different light-emitting substances may be stacked, in which case light-emitting substances may be selected so that the light emitted from each of the light-emitting substances has a complementary color relationship.

[0536] This embodiment mode can be implemented by appropriately combining at least a part thereof with other embodiment modes described in this specification.

[0537] Embodiment 5 In this embodiment, electronic devices of one embodiment of the present invention will be described with reference to FIGS.

[0538] 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 has high reliability. Furthermore, the display device of one embodiment of the present invention can easily achieve high definition and high resolution and can also achieve high display quality. Therefore, the display device of one embodiment of the present invention can be used in the display portions of various electronic devices.

[0539] Examples of electronic devices include electronic devices with relatively large screens such as television sets, desktop or notebook personal computers, computer monitors, digital signage, and 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.

[0540] In particular, the display device of one embodiment of the present invention can be suitably used in electronic devices having a relatively small display area because it can increase the resolution. Examples of such electronic devices include wristwatch-type and bracelet-type information terminals (wearable devices), and head-mounted wearable devices such as VR devices such as head-mounted displays, AR glasses-type devices, and MR devices.

[0541] The display device of one embodiment of the present invention preferably has an extremely high resolution, such as HD (1280 × 720 pixels), FHD (1920 × 1080 pixels), WQHD (2560 × 1440 pixels), WQXGA (2560 × 1600 pixels), 4K (3840 × 2160 pixels), or 8K (7680 × 4320 pixels). A resolution of 4K, 8K, or higher is particularly preferable. Furthermore, the pixel density (resolution) of the display device of one embodiment of the present invention is preferably 100 ppi or higher, more preferably 300 ppi or higher, more preferably 500 ppi or higher, more preferably 1000 ppi or higher, more preferably 2000 ppi or higher, more preferably 3000 ppi or higher, more preferably 5000 ppi or higher, and even more preferably 7000 ppi or higher. By using a display device having either or both of high resolution and high definition, it is possible to further enhance the sense of realism and depth in electronic devices for personal use, such as portable or home use. Furthermore, the screen ratio (aspect ratio) of the display device of one embodiment of the present invention is not particularly limited. For example, the display device can support various screen ratios such as 1:1 (square), 4:3, 16:9, and 16:10.

[0542] The electronic device of this embodiment may have a sensor (including the function of detecting, detecting, or 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).

[0543] 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, and a function to read out programs or data recorded on a recording medium.

[0544] 29A to 29D , examples of wearable devices that can be worn on the head are described. These wearable devices have one or both of a function for displaying AR content and a function for displaying VR content. Note that these wearable devices may also have a function for displaying SR or MR content in addition to AR and VR. By having an electronic device have a function for displaying at least one of AR, VR, SR, and MR content, it is possible to enhance the user's sense of immersion.

[0545] The electronic device 700A shown in FIG. 29A and the electronic device 700B shown in FIG. 29B each have a pair of display devices 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.

[0546] The display device of one embodiment of the present invention can be applied to the display device 751. Therefore, the display device 751 can be a highly reliable electronic device capable of displaying images with extremely high definition.

[0547] The electronic device 700A and the electronic device 700B can each project an image displayed on the display device 751 onto a display area 756 of the optical member 753. Because the optical member 753 is translucent, the user can see the image displayed in the display area superimposed on a transmitted image visually recognized through the optical member 753. Therefore, the electronic device 700A and the electronic device 700B are each electronic devices capable of AR display.

[0548] The electronic device 700A and the electronic device 700B may be provided with a camera capable of capturing an image in front of them as an imaging unit. Furthermore, the electronic device 700A and the 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 the display area 756.

[0549] The communication unit has a wireless communication device, and can supply, for example, a video signal via the wireless communication device. Note that 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 can be connected may be provided.

[0550] Furthermore, the electronic device 700A and the electronic device 700B are provided with batteries, which can be charged wirelessly and / or by wire.

[0551] 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, a slide operation, or the like 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 broaden the range of operations.

[0552] 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, or an optical type. In particular, it is preferable to use a capacitance type or an optical type sensor in the touch sensor module.

[0553] When an optical touch sensor is used, a photoelectric conversion element (also called a photoelectric conversion device) can be used as a light receiving element (also called a light receiving device). The active layer of the photoelectric conversion element can be made of either an inorganic semiconductor or an organic semiconductor, or both.

[0554] The electronic device 800A shown in Figure 29C and the electronic device 800B shown in Figure 29D 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.

[0555] The display device of one embodiment of the present invention can be applied to the display portion 820. Therefore, the electronic device can be highly reliable and capable of displaying with extremely high definition. The extremely high-definition display can give a user a high sense of immersion.

[0556] The display unit 820 is provided inside the housing 821 at a position that can be viewed through the lens 832. In addition, by displaying different images on the pair of display units 820, it is possible to perform three-dimensional display using parallax.

[0557] The electronic device 800A and the electronic device 800B can be said to be electronic devices for VR. A user wearing the electronic device 800A or the electronic device 800B can view an image displayed on the display unit 820 through the lens 832.

[0558] 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.

[0559] The mounting unit 823 allows the user to mount the electronic device 800A or the electronic device 800B on the head. Note that, for example, in Fig. 29C and the like, the mounting unit 823 is shaped like the temples of glasses, but is not limited to this. The mounting unit 823 may be shaped like a helmet or a band, for example, as long as it can be worn by the user.

[0560] 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.

[0561] Although an example including the imaging unit 825 is shown here, a distance measuring sensor (hereinafter also referred to as a detection unit) capable of measuring the distance to an object may be provided. That is, the imaging unit 825 is one aspect of the detection unit. As the detection unit, for example, an image sensor or a range image sensor such as a LIDAR (Light Detection and Ranging) can be used. By using an image obtained by the camera and an image obtained by the range image sensor, more information can be obtained, enabling more accurate gesture operations.

[0562] The electronic device 800A may have a vibration mechanism that functions as a bone conduction earphone. For example, a configuration having such a vibration mechanism can be applied to one or more of the display unit 820, the housing 821, and the wearing unit 823. This allows a user to enjoy video and audio simply by wearing the electronic device 800A, without the need for separate audio equipment such as headphones, earphones, or speakers.

[0563] The electronic device 800A and the electronic device 800B may each have an input terminal to which, for example, a cable for supplying a video signal from a video output device and power for charging a battery provided in the electronic device can be connected.

[0564] The electronic device of one embodiment of the present invention may have a function of wireless communication with an earphone 750. The earphone 750 includes a communication unit (not shown) and has a wireless communication function. The earphone 750 can receive information (e.g., audio data) from the electronic device through the wireless communication function. For example, the electronic device 700A shown in FIG. 29A has a function of transmitting information to the earphone 750 through the wireless communication function. Furthermore, for example, the electronic device 800A shown in FIG. 29C has a function of transmitting information to the earphone 750 through the wireless communication function.

[0565] The electronic device may also have an earphone unit. Electronic device 700B shown in Fig. 29B has earphone unit 727. For example, earphone unit 727 and the control unit may be configured to be connected to each other by wire. Part of the wiring connecting earphone unit 727 and the control unit may be disposed inside housing 721 or attachment unit 723.

[0566] 29D includes an earphone unit 827. For example, the earphone unit 827 and the control unit 824 can be configured to be connected to each other by wire. Part of the wiring connecting the earphone unit 827 and the control unit 824 may be disposed inside the housing 821 or the attachment unit 823. The earphone unit 827 and the attachment unit 823 may also have magnets. This allows the earphone unit 827 to be fixed to the attachment unit 823 by magnetic force, which is preferable as it makes storage easier.

[0567] The electronic device may have an audio output terminal to which earphones, headphones, or the like 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.

[0568] As described above, as electronic devices of one embodiment of the present invention, both glasses-type devices (such as the electronic devices 700A and 700B) and goggle-type devices (such as the electronic devices 800A and 800B) are suitable.

[0569] The electronic device 6500 shown in FIG. 30A is a portable information terminal that can be used as a smartphone.

[0570] The electronic device 6500 includes a housing 6501, a display portion 6502, a power button 6503, a button 6504, a speaker 6505, a microphone 6506, a camera 6507, a light source 6508, and the like. The display portion 6502 has a touch panel function.

[0571] The display device of one embodiment of the present invention can be applied to the display portion 6502 .

[0572] FIG. 30B is a schematic cross-sectional view including the end of the housing 6501 on the microphone 6506 side.

[0573] A light-transmitting protective member 6510 is provided on the display surface side of the housing 6501, and a display device 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.

[0574] A display device 6511, an optical member 6512, and a touch sensor panel 6513 are fixed to the protective member 6510 by adhesive layers (not shown).

[0575] A part of the display device 6511 is folded back in an area outside the display portion 6502, 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.

[0576] The flexible display of one embodiment of the present invention can be applied to the display device 6511. Therefore, an extremely lightweight electronic device can be realized. Furthermore, since the display device 6511 is extremely thin, a large-capacity battery 6518 can be mounted thereon while suppressing the thickness of the electronic device. Furthermore, by folding back a part of the display device 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.

[0577] 30C shows an example of a television set. A television set 7100 has a display portion 7000 built into a housing 7101. Here, the housing 7101 is supported by a stand 7103.

[0578] 30C can be operated using operation switches provided on the housing 7101 and a separate remote control 7111. Alternatively, the display portion 7000 may be provided with a touch sensor, and the television set 7100 may be operated by touching the display portion 7000 with a finger, for example. The remote control 7111 may have a display portion that displays information output from the remote control 7111. Using operation keys or a touch panel provided on the remote control 7111, the channel and volume can be controlled, and an image displayed on the display portion 7000 can be controlled.

[0579] The television device 7100 is configured to include a receiver, a modem, and the like. Ordinary television broadcasts can be received using the receiver. Furthermore, by connecting to a wired or wireless communication network via the modem, it is possible to perform one-way (from a sender to a receiver) or two-way (between a sender and a receiver, or between receivers, etc.) information communication.

[0580] 30D 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, and an external connection port 7214. The housing 7211 includes a display portion 7000.

[0581] 30E and 30F show an example of digital signage.

[0582] 30E includes a housing 7301, a display portion 7000, and a speaker 7303. The digital signage 7300 may further include an LED lamp, operation keys (including a power switch or an operation switch), a connection terminal, various sensors, a microphone, and the like.

[0583] 30F 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.

[0584] 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.

[0585] Applying a touch panel to the display unit 7000 is preferable because it not only displays images or videos on the display unit 7000 but also allows the user to intuitively operate it. Furthermore, when used to provide information such as route information or traffic information, the intuitive operation can improve usability.

[0586] 30E and 30F , the digital signage 7300 or the digital signage 7400 is preferably capable of wirelessly linking with an information terminal 7311 or an information terminal 7411 carried by a user. For example, advertising information displayed on the display unit 7000 can be displayed on the screen of the information terminal 7311 or the information terminal 7411. By operating the information terminal 7311 or the information terminal 7411, the display on the display unit 7000 can be switched. Here, the information terminal 7311 and the information terminal 7411 can be, for example, a smartphone.

[0587] 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.

[0588] 30C to 30F, the display device of one embodiment of the present invention can be applied to the display portion 7000.

[0589] The electronic device shown in Figures 31A to 31G has a housing 9000, a display unit 9001, a speaker 9003, operation keys 9005 (including a power switch or an operation switch), a connection terminal 9006, a sensor 9007 (including a function to sense, detect, or measure force, displacement, position, speed, acceleration, angular velocity, rotation speed, distance, light, liquid, magnetism, temperature, chemical substance, sound, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, gradient, vibration, odor, or infrared rays), and a microphone 9008.

[0590] The electronic devices shown in Figures 31A to 31G 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, etc., a function to control processing using various software (programs), a wireless communication function, and a function to read and process programs or data recorded on a recording medium. Note that the functions of the electronic devices are not limited to these, and they may have various other functions. The electronic devices may have multiple display units. Furthermore, the electronic devices may be provided with, for example, a camera, which may capture still images or videos and store them on a recording medium (external or built-in to the camera), and may have functions such as displaying the captured images on the display unit.

[0591] The electronic devices shown in Figures 31A to 31G will be described in detail below.

[0592] FIG. 31A is a perspective view showing a mobile information terminal 9101. The mobile information terminal 9101 can be used as, for example, a smartphone. Note that the mobile information terminal 9101 may be provided with a speaker 9003, a connection terminal 9006, a sensor 9007, and the like. The mobile information terminal 9101 can display text and image information on multiple surfaces. FIG. 31A shows an example in which three icons 9050 are displayed. Information 9051, indicated by a dashed rectangle, can also be displayed on another surface of the display unit 9001. Examples of the information 9051 include notifications of incoming emails, SNS messages, and phone calls, the title of the email or SNS message, the sender's name, the date and time, the remaining battery level, and radio wave intensity. Alternatively, an icon 9050, for example, may be displayed in the position where the information 9051 is displayed.

[0593] 31B is a perspective view showing the mobile information terminal 9102. The mobile information terminal 9102 has a function of displaying information on three or more surfaces of the display unit 9001. Here, an example is shown in which information 9052, information 9053, and information 9054 are displayed on different surfaces. For example, a user can check information 9053 displayed in a position that can be observed from above the mobile information terminal 9102 while storing the mobile information terminal 9102 in a breast pocket of clothes. The user can check the display without taking the mobile information terminal 9102 out of the pocket and decide, for example, whether to answer a call.

[0594] 31C is a perspective view showing a tablet terminal 9103. The tablet terminal 9103 is capable of executing various applications such as mobile phone calls, e-mail, text browsing and creation, music playback, internet communication, and computer games, for example. The tablet terminal 9103 has a display unit 9001, a camera 9002, a microphone 9008, and a speaker 9003 on the front side of a housing 9000, operation keys 9005 as operation buttons on the left side of the housing 9000, and a connection terminal 9006 on the bottom.

[0595] FIG. 31D is a perspective view showing a wristwatch-type mobile information terminal 9200. The mobile information terminal 9200 can be used as, for example, a smart watch (registered trademark). The display surface of the display unit 9001 is curved, and display can be performed along the curved display surface. The mobile information terminal 9200 can also perform hands-free calling by communicating with, for example, a headset capable of wireless communication. The mobile information terminal 9200 can also perform data transmission and charging with another information terminal through a connection terminal 9006. Note that charging may be performed by wireless power supply.

[0596] 31E to 31G are perspective views showing a foldable mobile information terminal 9201. Also, FIG. 31E is a perspective view of the mobile information terminal 9201 in an unfolded state, FIG. 31G is a perspective view of the mobile information terminal 9201 in a folded state, and FIG. 31F is a perspective view of a state in the process of changing from one of FIG. 31E and FIG. 31G to the other. The mobile information terminal 9201 has excellent portability in a folded state, and excellent display visibility due to a seamless, wide display area in an unfolded state. The display portion 9001 of the mobile information terminal 9201 is supported by three housings 9000 connected by hinges 9055. For example, the display portion 9001 can be bent with a curvature radius of 0.1 mm or more and 150 mm or less.

[0597] By applying the display device of one embodiment of the present invention to the above-described electronic devices, highly reliable electronic devices can be provided.

[0598] This embodiment mode can be implemented by appropriately combining at least a part thereof with other embodiment modes described in this specification.

[0599] 100: display device, 101: layer, 103: pixel, 110a: sub-pixel, 110b: sub-pixel, 110c: sub-pixel, 110: sub-pixel, 111a: pixel electrode, 111b: pixel electrode, 111c: pixel electrode, 111: pixel electrode, 113a: EL layer, 113A: EL film, 113b: EL layer, 113B: EL film, 113c: EL layer, 113C: EL film, 113d: EL layer, 113: EL layer, 114: common layer, 115: common electrode, 116: protrusion, 117: insulating layer, 118a: mask layer, 118A: mask film, 118b: mask layer, 118B: mask film, 118c: mask layer, 118C: mask film, 118: mask layer, 119a: mask layer, 119A: mask film, 119b: mask layer, 119B: mask film, 119c: mask layer, 119C: mask film, 119: mask layer, 120: substrate, 122: adhesive layer, 123: conductive layer, 124a: pixel, 124b: pixel, 125A: insulating film, 125: insulating layer, 127A: insulating film, 127B: insulating layer, 127C: insulating layer, 127: insulating layer, 130a: light-emitting element, 130b: light-emitting element, 130c: light-emitting element, 130d: light-emitting element, 130: light-emitting element, 131: protective layer, 133: counterbore portion, 135A: Light-shielding film, 135: light-shielding layer, 137a: tapered portion, 137b: tapered portion, 137c: tapered portion, 137: tapered portion, 139a: region, 139b: region, 140: connecting portion, 150: pixel, 160a: light-emitting unit, 160b: light-emitting unit, 160c: light-emitting unit, 160: light-emitting unit, 161: protective layer, 163a: colored layer, 163b: colored layer, 163c: colored layer, 163: colored layer, 190a: resist mask, 190b: resist mask, 190c: resist mask, 200A: display device, 200B: display device, 200C: display device, 200D: display device , 200E: display device, 200F: display device, 202: transistor, 204: connection portion, 209: transistor, 210: transistor, 211: insulating layer, 212: insulating layer, 214: insulating layer, 215: insulating layer, 218: insulating layer, 221: conductive layer, 222a: conductive layer, 222b: conductive layer, 223: conductive layer, 225: insulating layer, 231i: channel formation region, 231n: low resistance region, 231: semiconductor layer, 240: capacitance, 241: conductive layer, 242: connection layer, 243: insulating layer, 245: conductive layer, 251: conductive layer, 252: conductive layer, 254: insulating layer, 255a: insulating layer,255b: insulating layer, 255c: insulating layer, 256: plug, 261: insulating layer, 262: insulating layer, 263: insulating layer, 264: insulating layer, 265: insulating layer, 271: plug, 274a: conductive layer, 274b: conductive layer, 274: plug, 280: display module, 281: display section, 282: circuit section, 283a: pixel circuit, 283: pixel circuit section, 284a: pixel, 284: pixel section, 285: terminal section, 286: wiring section, 290: FPC, 291: substrate, 292: substrate, 301A: substrate, 301B: substrate, 301: substrate, 310A: transistor, 310B: transistor , 310: transistor, 311: conductive layer, 312: low resistance region, 313: insulating layer, 314: insulating layer, 315: element isolation layer, 320A: transistor, 320B: transistor, 320: transistor, 321: semiconductor layer, 323: insulating layer, 324: conductive layer, 325: conductive layer, 326: insulating layer, 327: conductive layer, 328: insulating layer, 329: insulating layer, 331: substrate, 332: insulating layer, 335: insulating layer, 336: insulating layer, 341: conductive layer, 342: conductive layer, 343: plug, 344: insulating layer, 345: insulating layer, 346: insulating layer, 347: bump, 348: adhesion layer, 400: display device, 411a: conductive layer, 411b: conductive layer, 451: substrate, 455: adhesive layer, 462: display unit, 464: circuit, 465: wiring, 466: conductive layer, 472: FPC, 473: IC, 700A: electronic device, 700B: electronic device, 711: light-emitting layer, 712: light-emitting layer, 713: light-emitting layer, 720: layer, 721: housing, 723: wearing unit, 727: earphone unit, 730: layer, 750: earphone, 751: display device, 753: optical member, 756: display area, 757: frame, 758: nose pad, 790a: EL layer, 790b: EL layer, 790: EL layer , 791: lower electrode, 792: upper electrode, 795: colored layer, 800A: electronic device, 800B: electronic device, 820: display unit, 821: housing, 822: communication unit, 823: wearing unit, 824: control unit, 825: imaging unit, 827: earphone unit, 832: lens, 6500: electronic device, 6501: housing, 6502: display unit, 6503: power button, 6504: button, 6505: speaker, 6506: microphone, 6507: camera, 6508: light source, 6510: protective member, 6511: display device, 6512: optical member, 6513: touch sensor panel, 6515: FPC,6516: IC, 6517: printed circuit board, 6518: battery, 7000: display unit, 7100: television device, 7101: housing, 7103: stand, 7111: remote control device, 7200: notebook personal computer, 7211: housing, 7212: keyboard, 7213: pointing device, 7214: external connection port, 7300: digital signage, 7301: housing, 7303: speaker, 7311: information terminal, 7400: digital signage page, 7401: pillar, 7411: information terminal, 9000: housing, 9001: display unit, 9002: camera, 9003: speaker, 9005: operation keys, 9006: connection terminal, 9007: sensor, 9008: microphone, 9050: icon, 9051: information, 9052: information, 9053: information, 9054: information, 9055: hinge, 9101: mobile information terminal, 9102: mobile information terminal, 9103: tablet terminal, 9200: mobile information terminal, 9201: mobile information terminal,

Claims

1. a first light-emitting element; a second light-emitting element arranged adjacent to the first light-emitting element; a first insulating layer having a region provided between the first light-emitting element and the second light-emitting element; a light-shielding layer having a region located above the first insulating layer; a second insulating layer having a region located above the light-shielding layer, and having, the first light-emitting element has a first pixel electrode, a first EL layer above the first pixel electrode, and a common electrode above the first EL layer; the second light-emitting element has a second pixel electrode, a second EL layer above the second pixel electrode, and the common electrode above the second EL layer; the common electrode is disposed above the second insulating layer; in a cross-sectional view, each of the first pixel electrode and the second pixel electrode has a tapered shape; the first EL layer has a region covering a side surface of the first pixel electrode; the second EL layer has a region covering a side surface of the second pixel electrode; the first EL layer has a first tapered portion between a side surface of the first pixel electrode and the first insulating layer; the second EL layer has a second tapered portion between a side surface of the second pixel electrode and the first insulating layer, a display device.

2. In claim 1, the first insulating layer has an inorganic material; the second insulating layer has an organic material, a display device.

3. In claim 2, the first insulating layer has aluminum oxide, a display device.

4. In claim 2 or 3, the second insulating layer has an acrylic resin, a display device.

5. In any one of claims 1 to 4, a taper angle of the first tapered portion and a taper angle of the second tapered portion are each less than 90°, a display device.

6. In any one of claims 1 to 5, the first insulating layer has a region in contact with the first EL layer and the second EL layer, a display device.

7. In any one of claims 1 to 6, the first light-emitting element has a common layer disposed between the first EL layer and the common electrode; the second light-emitting element has the common layer disposed between the second EL layer and the common electrode; the common layer is disposed between the second insulating layer and the common electrode; the common layer has at least one 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, a display device.

8. Form a first pixel electrode and a second pixel electrode. Form a first EL film covering the first pixel electrode and the second pixel electrode. Form a first mask film on the first EL film. By processing the first EL film and the first mask film, form a first EL layer on the first pixel electrode and a first mask layer on the first EL layer. Form a second EL film covering the first mask layer and the second pixel electrode. Form a second mask film on the second EL film. By processing the second EL film and the second mask film, form a second EL layer on the second pixel electrode and a second mask layer on the second EL layer. Form an inorganic insulating film covering the first EL layer, the second EL layer, the first mask layer, and the second mask layer. Form a light-shielding film on the inorganic insulating film. Apply a photosensitive organic insulating film on the light-shielding film. Irradiate light onto a part of the organic insulating film. Remove a part of the organic insulating film to form an organic insulating layer between the first EL layer and the second EL layer. Remove a part of the light-shielding film to form a light-shielding layer under the organic insulating layer. Remove a part of the inorganic insulating film to form an inorganic insulating layer under the light-shielding layer. A method for manufacturing a display device, comprising forming a common electrode on the first EL layer, the second EL layer, and the organic insulating layer.

9. In claim 8, A method for manufacturing a display device, wherein the light includes ultraviolet light.

10. In claim 8 or 9, Form the first pixel electrode and the second pixel electrode to each have a tapered shape on the side surface in a cross-sectional view of the display device. Form the first EL layer to cover the side surface of the first pixel electrode and have a first tapered portion between the side surface of the first pixel electrode and the first mask layer. A method for manufacturing a display device, wherein the second EL layer is formed to cover the side surface of the second pixel electrode and have a second tapered portion between the side surface of the second pixel electrode and the second mask layer.

11. In claim 10, The first EL layer is formed such that the taper angle of the first tapered portion is less than 90°. A method for manufacturing a display device, wherein the second EL layer is formed such that the taper angle of the second tapered portion is less than 90°.

12. In any one of claims 8 to 11, A method for manufacturing a display device, in which the first EL layer and the second EL layer are formed using a photolithography method.

13. In any one of Claims 8 to 12, A method for manufacturing a display device, in which a region where the distance between the first EL layer and the second EL layer is 8 μm or less is provided.

14. In any one of Claims 8 to 13, A method for manufacturing a display device, in which the inorganic insulating film is formed using an ALD method.

15. In any one of Claims 8 to 14, A method for manufacturing a display device, in which the organic insulating film is formed using a photosensitive acrylic resin.

16. In any one of Claims 8 to 15, A method for manufacturing a display device, in which the inorganic insulating layer is formed so as to have a region in contact with the first EL layer and the second EL layer.

17. In any one of Claims 8 to 16, After forming the inorganic insulating layer and before forming the common electrode, a common layer having at least one 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 is formed, A method for manufacturing a display device, in which the common electrode is formed on the common layer.