Display device, display module, electronic device, and method for producing display device

Abstract

The present invention provides a display device demonstrating high reliability. The display device has a first light-emitting element, a second light-emitting element adjoining the first light-emitting element, a first insulating layer disposed between the first light-emitting element and the second light-emitting element, and a second insulating layer disposed on the first insulating layer. The first light-emitting element has a first electrically conductive layer, a second electrically conductive layer covering upper and side surfaces of the first electrically conductive layer, a first EL layer covering upper and side surfaces of the second electrically conductive layer, and a common electrode disposed on the first EL layer. The second light-emitting element has a third electrically conductive layer, a fourth electrically conductive layer covering upper and side surfaces of the third electrically conductive layer, a second EL layer covering upper and side surfaces of the fourth electrically conductive layer, and a common electrode disposed on the second EL layer. A common electrode is disposed on the second insulating layer. The first electrically conductive layer has a higher reflectance to visible light than the reflectance of the second electrically conductive layer to visible light, and the third electrically conductive layer has a higher reflectance to visible light than the reflectance of the fourth electrically conductive layer to visible light.

Description

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

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

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

[0003] In recent years, display devices have been expected to be used in a variety of applications. For example, applications of large display devices include home television devices (also referred to as televisions or television receivers), digital signage, and public information displays (PIDs). In addition, development of mobile information terminals, such as smartphones and tablet terminals equipped with touch panels, is progressing.

[0004] There is also a demand for higher definition display devices. Devices requiring high-definition display devices, such as devices for virtual reality (VR), augmented reality (AR), substitutional reality (SR), and mixed reality (MR), are being actively developed.

[0005] As a display device, for example, a light-emitting device having a light-emitting element (also called a light-emitting device) has been developed. A light-emitting element (also called an EL element or an organic EL element) utilizing an electroluminescence (EL) phenomenon has characteristics such as being easily thin and lightweight, being capable of high-speed response to an input signal, and being capable of being driven by a DC constant voltage power supply, and is therefore applied to a display device.

[0006] Patent Document 1 discloses a display device for VR that uses an organic EL element (also called an organic EL device).

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

[0008] 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, pp. 16-18 (2008)

[0010] For example, an organic EL element can have a structure in which a layer containing an organic compound is sandwiched between a pair of electrodes. Here, if the electrodes have a stacked structure of multiple layers made of different materials, the electrodes may be altered due to, for example, reactions between the multiple layers, which may result in a decrease in the yield of the display device.

[0011] In view of the above, an object of one embodiment of the present invention is to provide a highly reliable display device. Another object of one embodiment of the present invention is to provide a display device including a light-emitting element with high emission efficiency. Another object of one embodiment of the present invention is to provide a display device with low power consumption. Another object of one embodiment of the present invention is to provide a display device with high light extraction efficiency. Another object of one embodiment of the present invention is to provide a low-cost display device. Another object of one embodiment of the present invention is to provide a display device with high display quality. Another object of one embodiment of the present invention is to provide a high-resolution display device. Another object of one embodiment of the present invention is to provide a novel display device.

[0012] Another object of one embodiment of the present invention is to provide a method for manufacturing a display device with high yield. Another object of one embodiment of the present invention is to provide a method for manufacturing a display device with high reliability. Another object of one embodiment of the present invention is to provide a method for manufacturing a display device including a light-emitting element with high emission efficiency. Another object of one embodiment of the present invention is to provide a method for manufacturing a display device with low power consumption. Another object of one embodiment of the present invention is to provide a method for manufacturing a display device with high light extraction efficiency. Another object of one embodiment of the present invention is to provide a method for manufacturing a display device with high display quality. Another object of one embodiment of the present invention is to provide a method for manufacturing a high-resolution display device. Another object of one embodiment of the present invention is to provide a method for manufacturing a high-resolution display device. Another object of one embodiment of the present invention is to provide a novel method for manufacturing a display device.

[0013] Note that the description of these problems does not preclude the existence of other problems. One embodiment of the present invention does not necessarily have to solve all of these problems. Problems other than these can be extracted from the description in the specification, drawings, and claims.

[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, and a second insulating layer over the first insulating layer, in which the first light-emitting element includes a first conductive layer, a second conductive layer covering an upper surface and a side surface of the first conductive layer, a first EL layer over the second conductive layer, and a common electrode over the first EL layer, and the second light-emitting element includes a third conductive layer, a fourth conductive layer covering an upper surface and a side surface of the third conductive layer, a second EL layer over the fourth conductive layer, and a common electrode over the second EL layer, and the common electrode is provided over the second insulating layer. The first conductive layer has a higher reflectance to visible light than the second conductive layer, and the third conductive layer has a higher reflectance to visible light than the fourth conductive layer.

[0015] Alternatively, in the above aspect, the first EL layer may have a first functional layer having a region in contact with the second conductive layer and a first light-emitting layer on the first functional layer, and the second EL layer may have a second functional layer having a region in contact with the fourth conductive layer and a second light-emitting layer on the second functional layer.

[0016] Alternatively, in the above aspect, the first functional layer and the second functional layer may have at least one of a hole injection layer or a hole transport layer, the work function of the second conductive layer may be greater than the work function of the first conductive layer, and the work function of the fourth conductive layer may be greater than the work function of the third conductive layer.

[0017] Alternatively, in the above aspect, the first light-emitting element may have a common layer between the first EL layer and the common electrode, and the second light-emitting element may have a common layer between the second EL layer and the common electrode, the common layer being located between the second insulating layer and the common electrode, and the common layer may have at least one of an electron injection layer or an electron transport layer.

[0018] Alternatively, in the above aspect, the first functional layer and the second functional layer may have at least one of an electron injection layer or an electron transport layer, the work function of the second conductive layer may be smaller than the work function of the first conductive layer, and the work function of the fourth conductive layer may be smaller than the work function of the third conductive layer.

[0019] Alternatively, in the above aspect, the first light-emitting element may have a common layer between the first EL layer and the common electrode, and the second light-emitting element may have a common layer between the second EL layer and the common electrode, the common layer being located between the second insulating layer and the common electrode, and the common layer may have at least one of a hole injection layer or a hole transport layer.

[0020] Alternatively, in the above aspect, the second conductive layer and the fourth conductive layer may contain an oxide having any one or more selected from the group consisting of indium, tin, zinc, gallium, titanium, aluminum, and silicon.

[0021] Alternatively, in the above aspect, the first insulating layer may have an area in contact with a side surface of the first EL layer and a side surface of the second EL layer, and cover a portion of an upper surface of the first EL layer and a portion of an upper surface of the second EL layer, and in a cross-sectional view, an end of the second insulating layer may have a tapered shape with a taper angle of less than 90°, and the second insulating layer may cover at least a portion of the side surface of the first insulating layer.

[0022] Alternatively, in the above aspect, the end portion of the first insulating layer may have a tapered shape with a taper angle of less than 90° in a cross-sectional view.

[0023] Alternatively, in the above aspect, the first insulating layer may be an inorganic insulating layer, and the second insulating layer may be an organic insulating layer.

[0024] Alternatively, in the above aspect, the first insulating layer may include aluminum oxide, and the second insulating layer may include acrylic resin.

[0025] Another aspect of the present invention is a display module including a display device according to one aspect of the present invention and at least one of a connector and an integrated circuit.

[0026] An electronic device including a display module according to one embodiment of the present invention and at least one of a housing, a battery, a camera, a speaker, and a microphone is also one embodiment of the present invention.

[0027] Another embodiment of the present invention is a method for manufacturing a display device, including forming a first conductive layer, forming a second conductive layer that covers an upper surface and side surfaces of the first conductive layer and has a lower reflectivity for visible light than the first conductive layer, forming an EL film over the second conductive layer, forming a mask film over the EL film, and processing the EL film and the mask film to form an EL layer over the second conductive layer and a mask layer over the EL layer.

[0028] Alternatively, in the above embodiment, after the second conductive layer is formed and before the EL film is formed, the second conductive layer may be subjected to a hydrophobic treatment.

[0029] Alternatively, in the above embodiment, the second conductive layer may be subjected to a hydrophobic treatment by being modified with fluorine.

[0030] Alternatively, one embodiment of the present invention includes forming a first conductive layer and a second conductive layer, forming a third conductive layer that covers an upper surface and side surfaces of the first conductive layer and has a lower reflectivity for visible light than the first conductive layer, and forming a fourth conductive layer that covers an upper surface and side surfaces of the second conductive layer and has a lower reflectivity for visible light than the second conductive layer, forming a first EL film on the third conductive layer and the fourth conductive layer, forming a first mask film on the first EL film, processing the first EL film and the first mask film to form the first EL layer on the third conductive layer and the first mask layer on the first EL layer, exposing the fourth conductive layer, and forming a first mask film on the first mask layer and the fourth conductive layer. a second EL film; a second mask film; the second EL film and the second mask film are processed to form a second EL layer on a fourth conductive layer and a second mask layer on the second EL layer; the first mask layer is exposed; insulating films are formed on the first mask layer and the second mask layer using a photosensitive material; the insulating film is processed to form an insulating layer between the first EL layer and the second EL layer; an etching treatment is performed using the insulating layer as a mask to expose top surfaces of the first EL layer and the second EL layer; and a common electrode is formed on the first EL layer, the second EL layer, and the insulating layer.

[0031] Alternatively, in the above embodiment, after the third conductive layer and the fourth conductive layer are formed and before the first EL film is formed, the third conductive layer and the fourth conductive layer may be subjected to a hydrophobic treatment.

[0032] Alternatively, in the above embodiment, the third conductive layer and the fourth conductive layer may be subjected to a hydrophobic treatment by fluorine modification.

[0033] Alternatively, in the above embodiment, the etching process may be performed by wet etching.

[0034] According to one embodiment of the present invention, a highly reliable display device can be provided. According to another embodiment of the present invention, a display device including a light-emitting element with high emission efficiency can be provided. According to another embodiment of the present invention, a display device with low power consumption can be provided. According to another embodiment of the present invention, a display device with high light extraction efficiency can be provided. According to another embodiment of the present invention, a low-cost display device can be provided. According to another embodiment of the present invention, a display device with high display quality can be provided. According to another embodiment of the present invention, a high-resolution display device can be provided. According to another embodiment of the present invention, a novel display device can be provided.

[0035] According to one embodiment of the present invention, a method for manufacturing a display device with high yield can be provided. According to one embodiment of the present invention, a method for manufacturing a display device with high reliability can be provided. According to one embodiment of the present invention, a method for manufacturing a display device including a light-emitting element with high emission efficiency can be provided. According to one embodiment of the present invention, a method for manufacturing a display device with low power consumption can be provided. According to one embodiment of the present invention, a method for manufacturing a display device with high light extraction efficiency can be provided. According to one embodiment of the present invention, a method for manufacturing a display device with high display quality can be provided. According to one embodiment of the present invention, a method for manufacturing a high-resolution display device can be provided. According to one embodiment of the present invention, a method for manufacturing a high-resolution display device can be provided. According to one embodiment of the present invention, a novel method for manufacturing a display device can be provided.

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

[0037] FIG. 1 is a plan view showing an example of the configuration of a display device. FIG. 2A is a cross-sectional view showing an example of the configuration of a display device. FIGS. 2B1 and 2B2 are cross-sectional views showing an example of the configuration of a pixel electrode. FIGS. 3A and 3B are cross-sectional views showing an example of the configuration of a pixel electrode. FIGS. 4A to 4C are cross-sectional views showing an example of the configuration of a pixel electrode. FIGS. 5A and 5B are cross-sectional views showing an example of the configuration of a display device. FIGS. 6A and 6B are cross-sectional views showing an example of the configuration of a display device. FIGS. 7A and 7B are cross-sectional views showing an example of the configuration of a display device. FIGS. 8A and 8B are cross-sectional views showing an example of the configuration of a display device. FIGS. 9A and 9B are cross-sectional views showing an example of the configuration of a display device. FIG. 10 is a cross-sectional view showing an example of the configuration of a display device. FIGS. 11A and 11B are cross-sectional views showing an example of the configuration of a display device. FIGS. 12A and 12B are cross-sectional views showing an example of the configuration of a display device. FIGS. 13A and 13B are cross-sectional views showing an example of the configuration of a display device. FIG. 14 is a cross-sectional view showing an example of the configuration of a display device. FIGS. 15A and 15B are cross-sectional views showing a structural example of a display device. FIGS. 16A and 16B are cross-sectional views showing a structural example of a display device. FIGS. 17A and 17B are cross-sectional views showing a structural example of a display device. FIGS. 18A to 18F are cross-sectional views showing a structural example of a display device. FIGS. 19A and 19B are cross-sectional views showing a structural example of a display device. FIGS. 20A and 20B are cross-sectional views showing a structural example of a display device. FIGS. 21A and 21B are cross-sectional views showing a structural example of a display device. FIGS. 22A and 22B are cross-sectional views showing a structural example of a display device. FIG. 23 is a cross-sectional view showing a structural example of a display device. FIGS. 24A to 24D are cross-sectional views showing an example of a method for manufacturing a display device. FIGS. 25A to 25D are cross-sectional views showing an example of a method for manufacturing a display device. FIGS. 26A to 26D are cross-sectional views showing an example of a method for manufacturing a display device. FIGS. 27A, 27B1, and 27B2 are cross-sectional views showing an example of a method for manufacturing a display device. 28A and 28B are cross-sectional views illustrating an example of a method for manufacturing a display device. FIGS. 29A and 29B are cross-sectional views illustrating an example of a method for manufacturing a display device. FIGS. 30A and 30B are cross-sectional views illustrating an example of a method for manufacturing a display device. FIGS. 31A and 31B are cross-sectional views illustrating an example of a method for manufacturing a display device.32A, 32B, 32C, 32D1, and 32D2 are cross-sectional views showing an example of a manufacturing method of a display device. FIGS. 33A to 33D are cross-sectional views showing an example of a manufacturing method of a display device. FIGS. 34A to 34C are cross-sectional views showing an example of a manufacturing method of a display device. FIGS. 35A to 35C are cross-sectional views showing an example of a manufacturing method of a display device. FIGS. 36A to 36D are cross-sectional views showing an example of a manufacturing method of a display device. FIGS. 37A and 37B are cross-sectional views showing an example of a manufacturing method of a display device. FIGS. 38A to 38D are cross-sectional views showing an example of a manufacturing method of a display device. FIGS. 39A to 39D are cross-sectional views showing an example of a manufacturing method of a display device. FIGS. 40A to 40C are cross-sectional views showing an example of a manufacturing method of a display device. FIGS. 41A and 41B are cross-sectional views showing an example of a manufacturing method of a display device. FIGS. 42A and 42B are cross-sectional views showing an example of a manufacturing method of a display device. 43A to 43E are cross-sectional views showing an example of a method for manufacturing a display device. FIGS. 44A to 44D are cross-sectional views showing an example of a method for manufacturing a display device. FIGS. 45A to 45C are cross-sectional views showing an example of a method for manufacturing a display device. FIGS. 46A and 46B are cross-sectional views showing an example of a configuration of a display device. FIGS. 47A and 47B are cross-sectional views showing an example of a configuration of a display device. FIGS. 48A to 48G are plan views showing an example of a configuration of a pixel. FIGS. 49A to 49I are plan views showing an example of a configuration of a pixel. FIGS. 50A and 50B are perspective views showing an example of a configuration of a display module. FIGS. 51A and 51B are cross-sectional views showing an example of a configuration of a display device. FIGS. 52A and 52B are cross-sectional views showing an example of a configuration of a display device. FIG. 53 is a cross-sectional view showing an example of a configuration of a display device. FIG. 54 is a cross-sectional view showing an example of a configuration of a display device. FIG. 55 is a cross-sectional view showing an example of a configuration of a display device. FIG. 56 is a cross-sectional view showing an example of a configuration of a display device. FIG. 57 is a cross-sectional view showing an example of a configuration of a display device. Fig. 58 is a cross-sectional view showing an example of the configuration of a display device. Fig. 59 is a cross-sectional view showing an example of the configuration of a display device. Fig. 60 is a cross-sectional view showing an example of the configuration of a display device. Fig. 61 is a cross-sectional view showing an example of the configuration of a display device. Fig. 62 is a cross-sectional view showing an example of the configuration of a display device. Fig. 63 is a cross-sectional view showing an example of the configuration of a display device. Fig. 64 is a cross-sectional view showing an example of the configuration of a display device.FIG. 65 is a cross-sectional view showing an example of the configuration of a display device. FIG. 66 is a cross-sectional view showing an example of the configuration of a display device. FIG. 67 is a cross-sectional view showing an example of the configuration of a display device. FIG. 68 is a cross-sectional view showing an example of the configuration of a display device. FIG. 69 is a perspective view showing an example of the configuration of a display device. FIG. 70A is a cross-sectional view showing an example of the configuration of a display device. FIGS. 70B1 and 70B2 are cross-sectional views showing examples of the configuration of a transistor. FIG. 71 is a cross-sectional view showing an example of the configuration of a display device. FIG. 72 is a cross-sectional view showing an example of the configuration of a display device. FIGS. 73A to 73B3 are cross-sectional views showing an example of the configuration of a display device. FIGS. 74A to 74B3 are cross-sectional views showing an example of the configuration of a display device. FIGS. 75A to 75C are cross-sectional views showing an example of the configuration of a display device. FIGS. 76A to 76F are cross-sectional views showing an example of the configuration of a light-emitting element. FIGS. 77A to 77C are cross-sectional views showing an example of the configuration of a light-emitting element. FIGS. 78A to 78D are diagrams showing examples of electronic devices. FIGS. 79A to 79F are diagrams showing examples of electronic devices. FIGS. 80A to 80G are diagrams showing examples of electronic devices.

[0038] The following description of the preferred embodiments will be given in detail with reference to the accompanying drawings. However, the present invention is not limited to the following description, and it will be readily understood by those skilled in the art that various modifications can be made to the modes and details of the present invention without departing from the spirit and scope of the present invention. Therefore, the present invention should not be interpreted as being limited to the description of the preferred embodiments shown below.

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

[0041] It should be noted that the terms "film" and "layer" can be interchangeable in some cases or depending on the situation. For example, the term "conductive layer" can be changed to the term "conductive film" in some cases. Or, for example, the term "insulating film" can be changed to the term "insulating layer" in some cases.

[0042] In this specification, terms indicating position, such as "above," "below," "upward," or "below" may be used for convenience in describing the positional relationship between components with reference to the drawings. Furthermore, the positional relationship between components changes as appropriate depending on the direction in which each configuration is depicted. Therefore, the terms are not limited to those described in this specification, and can be rephrased appropriately depending on the situation. For example, the expression "an insulating layer located above a conductive layer" can be rephrased as "an insulating layer located below a conductive layer" by rotating the orientation of the drawing by 180 degrees.

[0043] 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.

[0044] 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.

[0045] In this specification and the like, a light-emitting element has an EL layer between a pair of electrodes. The EL layer has at least a light-emitting layer. Here, examples of layers included in the EL layer include a light-emitting layer, a carrier injection layer, a carrier transport layer, and a carrier block layer.

[0046] In this specification and the like, the term "carrier injection layer" refers to one or both of a hole injection layer and an electron injection layer, the term "carrier transport layer" refers to one or both of a hole transport layer and an electron transport layer, and the term "carrier block layer" refers to one or both of a hole block layer and an electron block layer.

[0047] In this specification, a tapered shape refers to a shape in which at least a portion of the side surface of a structure is inclined with respect to the substrate surface. For example, it refers to a shape having a region in which the angle between the inclined side surface and the substrate surface (also referred to as the taper angle) is less than 90°. Note that the side surface of the structure and the substrate surface do not necessarily need to be completely flat, and may be approximately planar with a slight curvature or approximately planar with a slight unevenness.

[0048] Embodiment 1 In this embodiment, a display device according to one embodiment of the present invention and a manufacturing method thereof will be described.

[0049] A display device according to one embodiment of the present invention can display full colors. For example, a display device capable of displaying full colors can be manufactured by separately preparing EL layers each having a light-emitting layer for each light-emitting color. Alternatively, a display device capable of displaying full colors can be manufactured by providing a colored layer (also referred to as a color filter) on an EL layer that emits white light.

[0050] A structure in which different light-emitting layers are formed or painted separately for each light-emitting element of each color (e.g., blue (B), green (G), and red (R)) is sometimes called an SBS (Side By Side) structure. Also, a light-emitting element that can emit white light is sometimes called a white light-emitting element.

[0051] When manufacturing a display device having a plurality of light-emitting elements each emitting a different color, it is necessary to form the light-emitting layers each emitting a different color in an island shape. Even when manufacturing a display device having a white light-emitting element, forming the light-emitting layers in an island shape is preferable because it can reduce leakage current that may occur between adjacent light-emitting elements via the light-emitting layers.

[0052] In this specification, the term "island-like" refers to a state in which two or more layers made of the same material and formed in the same process are physically separated. For example, an island-like light-emitting layer refers to a state in which the light-emitting layer is physically separated from the adjacent light-emitting layer.

[0053] For example, island-shaped light-emitting layers can be formed by vacuum deposition using a metal mask. However, with this method, deviations in the shape and position of the island-shaped light-emitting layers from the design occur 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. This makes it difficult to achieve high-definition and high-aperture ratio displays. Furthermore, during deposition, the contours of the layer may become blurred, resulting in thin edges. In other words, the thickness of the island-shaped light-emitting layer may vary depending on the location. Furthermore, when fabricating large, high-resolution, or high-definition display devices, there is a concern that low manufacturing yields may be caused by low dimensional accuracy of the metal mask and deformation due to heat, etc.

[0054] Therefore, when manufacturing a display device according to one embodiment of the present invention, the light-emitting layer is processed into a fine pattern by photolithography without using a shadow mask such as a metal mask. Specifically, a pixel electrode is formed for each subpixel, and then the light-emitting layer is formed over the plurality of pixel electrodes. Then, the light-emitting layer is processed by photolithography to form one island-shaped light-emitting layer for each pixel electrode. This allows the light-emitting layer to be divided into subpixels, and an island-shaped light-emitting layer can be formed for each subpixel.

[0055] When the light-emitting layer is processed into an island shape, a structure in which the light-emitting layer is processed using photolithography directly above the light-emitting layer is conceivable. In this structure, the light-emitting layer may be damaged, for example, by processing, which may significantly impair reliability. Therefore, when manufacturing a display device according to one embodiment of the present invention, a method is preferably used in which a mask layer or the like is formed on the light-emitting layer as an EL layer and a functional layer located above the light-emitting layer, such as a carrier block layer, a carrier transport layer, or a carrier injection layer, more specifically, a hole block layer, an electron transport layer, or an electron injection layer, and the like, and the light-emitting layer and the functional layer are processed into an island shape. By applying this method, a highly reliable display device can be provided. By providing a functional layer between the light-emitting layer and the mask layer, the light-emitting layer can be prevented from being exposed to the outermost surface during the manufacturing process of the display device, thereby reducing damage to the light-emitting layer.

[0056] In this specification and the like, the mask film and the mask layer respectively refer to a film and a layer that are located above at least the light-emitting layer, more specifically, the layer that is processed into an island shape among the layers that constitute the EL layer, and that have the function of protecting the light-emitting layer during the manufacturing process. The mask film can also be called a sacrificial film or a protective film, and the mask layer can also be called a sacrificial layer or a protective layer.

[0057] The EL layer can have a functional layer not only above the light-emitting layer but also below the light-emitting layer. When the light-emitting layer is processed into an island shape, it is preferable to process a functional layer (e.g., a carrier injection layer, a carrier transport layer, or a carrier block layer; more specifically, a hole injection layer, a hole transport layer, or an electron block layer) located below the light-emitting layer into an island shape in the same pattern as the light-emitting layer. Processing a layer located below the light-emitting layer into an island shape in the same pattern as the light-emitting layer can reduce leakage current (also referred to as lateral leakage current) that may occur between adjacent subpixels. For example, when a hole injection layer is shared between adjacent subpixels, lateral leakage current may occur due to the hole injection layer. On the other hand, in a display device according to one embodiment of the present invention, the hole injection layer can be processed into an island shape in the same pattern as the light-emitting layer, so that lateral leakage current between adjacent subpixels is substantially eliminated or can be extremely reduced.

[0058] Here, it is preferable that the EL layer is provided so as to cover the upper and side surfaces of the pixel electrode, which makes it easier to increase the aperture ratio compared to a configuration in which the ends of the EL layer are located inside the ends of the pixel electrode.

[0059] Furthermore, the pixel electrode preferably has a laminated structure of multiple layers made of different materials. For example, when the display device is a top-emission type and the pixel electrode has a two-layer laminated structure of a first conductive layer and a second conductive layer on the first conductive layer, the first conductive layer can be a layer with a higher reflectivity for visible light than the second conductive layer. Furthermore, when the functional layer located below the light-emitting layer has, for example, at least one of a hole injection layer and a hole transport layer, and the second conductive layer is in contact with the functional layer, the second conductive layer can be a layer with a higher work function than the first conductive layer. In other words, when the pixel electrode functions as an anode, the second conductive layer can be a layer with a higher work function than the first conductive layer. As a result, a light-emitting element with high light extraction efficiency and low driving voltage can be obtained.

[0060] In this specification, visible light refers to light with a wavelength of 400 nm or more and less than 750 nm. Furthermore, the reflectance for visible light refers to the reflectance for light with a predetermined wavelength range among wavelengths of 400 nm or more and less than 750 nm. For example, the average or maximum reflectance for light with all wavelengths of 400 nm or more and less than 750 nm may be referred to as the reflectance for visible light. Furthermore, the reflectance for light with a specific wavelength among wavelengths of 400 nm or more and less than 750 nm may be referred to as the reflectance for visible light.

[0061] On the other hand, when a pixel electrode has a stacked structure of multiple layers using different materials, the pixel electrode may be altered due to, for example, a reaction between the multiple layers. For example, in a manufacturing method of a display device according to one embodiment of the present invention, when a film formed after the formation of a pixel electrode is removed by wet etching, a chemical solution may come into contact with the pixel electrode. When a pixel electrode has a stacked structure of multiple layers, galvanic corrosion may occur due to contact of the multiple layers with a chemical solution. This may cause alteration of at least one of the layers constituting the pixel electrode. Therefore, the yield of the display device may decrease. Furthermore, the reliability of the display device may decrease.

[0062] Therefore, in one embodiment of the present invention, a second conductive layer is formed to cover the top and side surfaces of the first conductive layer. This prevents a chemical solution from contacting the first conductive layer, even when a film formed after forming a pixel electrode including the first conductive layer and the second conductive layer is removed by wet etching. Therefore, for example, galvanic corrosion of the pixel electrode can be suppressed. As described above, the display device of one embodiment of the present invention can be manufactured with a high yield. Furthermore, the display device of one embodiment of the present invention can be a highly reliable display device in which defects are suppressed.

[0063] In light-emitting elements that emit light of different colors, it is not necessary to form all layers constituting the EL layer separately; some layers can be formed in the same process. In a manufacturing method of a display device according to one embodiment of the present invention, after some layers constituting the EL layer are formed in an island shape for each color, at least a part of the mask layer is removed, and the remaining layers constituting the EL layer (sometimes referred to as a common layer) and a common electrode (also referred to as an upper electrode) are formed in common for each color, that is, as a single film. For example, a carrier injection layer and a common electrode can be formed in common for each color.

[0064] On the other hand, the carrier injection layer is often a layer with relatively high conductivity among the EL layers. Therefore, if 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 if the common electrode comes into contact with the side surface of the EL layer or the side surface of the pixel electrode.

[0065] Therefore, the display device of one embodiment of the present invention includes an insulating layer that covers at least the side surfaces of the island-shaped light-emitting layers. In addition, the insulating layer preferably covers part of the top surface of the island-shaped light-emitting layers.

[0066] 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 and the common electrode, thereby preventing short circuits in the light-emitting element and improving the reliability of the light-emitting element.

[0067] In a cross-sectional view, the end of the insulating layer preferably has a tapered shape with a taper angle of less than 90°. This can prevent step disconnections in the common layer and common electrode provided on the insulating layer. Therefore, connection defects due to step disconnections can be prevented. In addition, it can prevent the common electrode from being locally thinned due to the step, which can increase electrical resistance.

[0068] In this specification, the term "step discontinuity" refers to a phenomenon in which a layer, film, or electrode is divided due to the shape of the surface on which it is formed, such as a step, or a portion with a locally thin film thickness is formed.

[0069] As described above, the island-shaped light-emitting layer manufactured by the manufacturing method of the display device according to one embodiment of the present invention is not formed using a fine metal mask, but is formed by forming the light-emitting layer on 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 light-emitting 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 layer on the light-emitting layer, damage to the light-emitting layer during the manufacturing process of the display device can be reduced, thereby improving the reliability of the light-emitting element.

[0070] Furthermore, while it is difficult to reduce the distance between adjacent light-emitting elements to less than 10 μm using a formation method using, for example, a fine metal mask, the photolithography method of one embodiment of the present invention allows the distance between adjacent light-emitting elements, adjacent EL layers, or adjacent pixel electrodes to be reduced to less than 10 μm, 5 μm or less, 3 μm or less, 2 μm or less, 1.5 μm or less, 1 μm or less, or 0.5 μm or less in a process on a glass substrate. Furthermore, by using, for example, an exposure apparatus for LSIs, the distance between adjacent light-emitting elements, adjacent EL layers, or adjacent pixel electrodes can be reduced to, for example, 500 nm or less, 200 nm or less, 100 nm or less, or even 50 nm or less in a process on a silicon substrate. This allows the area of ​​the non-light-emitting region that may exist between two light-emitting elements to be significantly reduced, enabling the aperture ratio to approach 100%. For example, in a display device of one embodiment of the present invention, the aperture ratio can be 40% or more, 50% or more, 60% or more, 70% or more, 80% or more, or even 90% or more, but less than 100%.

[0071] Increasing the aperture ratio of a display device can improve the reliability of the display device. More specifically, when the lifetime of a display device using an organic EL element and having an aperture ratio of 10% is taken as the reference, the lifetime of a display device having an aperture ratio of 20%, i.e., twice the reference aperture ratio, is approximately 3.25 times longer, and the lifetime of a display device having an aperture ratio of 40%, i.e., four times the reference aperture ratio, is approximately 10.6 times longer. Thus, as the aperture ratio increases, the current density flowing through the organic EL element can be reduced, thereby improving the lifetime of the display device. In the display device of one embodiment of the present invention, the aperture ratio can be increased, thereby improving the display quality of the display device. Furthermore, as the aperture ratio of the display device increases, excellent effects such as significantly improving the reliability of the display device, particularly its lifetime, are achieved.

[0072] Furthermore, the pattern of the light-emitting layer itself can be made much smaller than when a fine metal mask is used. Furthermore, for example, when a metal mask is used to separately form light-emitting layers, 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 light-emitting 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. Furthermore, the display device can be made smaller and lighter.

[0073] Specifically, the resolution of the display device of one embodiment of the present invention can be, for example, 2000 ppi or more, preferably 3000 ppi or more, more preferably 5000 ppi or more, and still more preferably 6000 ppi or more, and can be 20000 ppi or less, or 30000 ppi or less.

[0074] [Configuration Example 1] Fig. 1 is a plan view showing a configuration example of a display device 100. The display device 100 has a pixel section 107 in which a plurality of pixels 108 are arranged in a matrix. Each pixel 108 has sub-pixels 110R, 110G, and 110B. Fig. 1 shows two rows and six columns of sub-pixels 110, which together form two rows and two columns of pixels 108.

[0075] In this specification and the like, when describing matters common to, for example, the subpixels 110R, 110G, and 110B, they may be referred to as the subpixels 110. When describing matters common to other components distinguished by alphabets, they may also be described using symbols without the alphabets.

[0076] The sub-pixel 110R emits red light, the sub-pixel 110G emits green light, and the sub-pixel 110B emits blue light. This allows an image to be displayed in the pixel unit 107. Therefore, the pixel unit 107 can be referred to as a display unit. Note that in this embodiment, three sub-pixels of red (R), green (G), and blue (B) are described as an example, but three sub-pixels of yellow (Y), cyan (C), and magenta (M), etc., may also be used. Furthermore, the number of types of sub-pixels is not limited to three, and may be four or more. Examples of four sub-pixels include four sub-pixels of R, G, B, and white (W); four sub-pixels of R, G, B, and Y; and four sub-pixels of R, G, B, and infrared (IR).

[0077] 1 can also be said to have a stripe arrangement applied to the pixels 108. Note that the arrangement method that can be applied to the pixels 108 is not limited to this, and an arrangement method such as a stripe arrangement, an S-stripe arrangement, a delta arrangement, a Bayer arrangement, or a zigzag arrangement may also be applied, or a pentile arrangement, a diamond arrangement, or the like may also be applied.

[0078] 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.

[0079] 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. Note that sub-pixels of different colors may also be arranged side by side in the Y direction, and sub-pixels of the same color may also be arranged side by side in the X direction.

[0080] A region 141 and a connection portion 140 are provided outside the pixel portion 107, and the region 141 is provided between the pixel portion 107 and the connection portion 140. An EL layer 113 is provided in the region 141. Furthermore, a conductive layer 111C is provided in the connection portion 140.

[0081] 1 shows an example in which the region 141 and the connection portion 140 are located on the right side of the pixel portion 107 in a plan view, but the positions of the region 141 and the connection portion 140 are not particularly limited. The region 141 and the connection portion 140 may be provided in at least one of the upper side, right side, left side, and lower side of the pixel portion 107 in a plan view, and may be provided so as to surround the four sides of the pixel portion 107. The top surface shape of the region 141 and the connection portion 140 may be strip-shaped, L-shaped, U-shaped, frame-shaped, or the like. The region 141 and the connection portion 140 may be singular or plural.

[0082] 2A is a cross-sectional view taken along dashed dotted line A1-A2 in FIG. 1 , showing an example of the configuration of a pixel 108 provided in the pixel section 107. As shown in FIG. 2A , the display device 100 has an insulating layer 101, a conductive layer 102 on the insulating layer 101, an insulating layer 103 on the insulating layer 101 and on the conductive layer 102, an insulating layer 104 on the insulating layer 103, and an insulating layer 105 on the insulating layer 104. The insulating layer 101 is provided on a substrate (not shown). The insulating layer 105, the insulating layer 104, and the insulating layer 103 have openings that reach the conductive layer 102, and plugs 106 are provided to fill the openings.

[0083] In the pixel portion 107, a light-emitting element 130 is provided on the insulating layer 105 and on the plug 106. A protective layer 131 is provided so as to cover the light-emitting element 130. A substrate 120 is bonded to the protective layer 131 by a resin layer 122. In addition, an insulating layer 125 and an insulating layer 127 on the insulating layer 125 are provided between adjacent light-emitting elements 130.

[0084] 2A shows multiple cross sections of insulating layer 125 and insulating layer 127, but in a plan view of display device 100, insulating layer 125 and insulating layer 127 are each connected to one another. That is, display device 100 can be configured to have, for example, one insulating layer 125 and one insulating layer 127. Note that display device 100 may have multiple insulating layers 125 that are separated from one another, or may have multiple insulating layers 127 that are separated from one another.

[0085] 2A shows light-emitting elements 130R, 130G, and 130B. Light-emitting elements 130R, 130G, and 130B emit light of different colors. For example, light-emitting element 130R can emit red light, light-emitting element 130G can emit green light, and light-emitting element 130B can emit blue light. Furthermore, light-emitting element 130R, light-emitting element 130G, or light-emitting element 130B may emit light of cyan, magenta, yellow, white, infrared, or the like.

[0086] The display device of one embodiment of the present invention can be, for example, a top emission type display device that emits light in the direction opposite to the substrate on which the light-emitting element is formed.

[0087] As the light-emitting element 130, for example, an OLED (organic light-emitting diode) or a QLED (quantum-dot light-emitting diode) is preferably used. Examples of the light-emitting material included in the light-emitting element 130 include a fluorescent material (fluorescent material), a phosphorescent material (phosphorescent material), an inorganic compound (e.g., quantum dot material), and a material that exhibits thermally activated delayed fluorescence (thermally activated delayed fluorescence (TADF) material). Alternatively, an LED such as a micro LED (light-emitting diode) can be used as the light-emitting element 130.

[0088] The light-emitting element 130R has a conductive layer 111R on the plug 106 and on the insulating layer 105, a conductive layer 112R covering the upper and side surfaces of the conductive layer 111R, an EL layer 113R covering the upper and side surfaces of the conductive layer 112R, a common layer 114 on the EL layer 113R, and a common electrode 115 on the common layer 114. Here, the conductive layer 111R and the conductive layer 112R form a pixel electrode of the light-emitting element 130R. Note that in the light-emitting element 130R, the EL layer 113R and the common layer 114 can also be collectively referred to as an EL layer.

[0089] The light-emitting element 130G includes a conductive layer 111G on the plug 106 and on the insulating layer 105, a conductive layer 112G covering the upper and side surfaces of the conductive layer 111G, an EL layer 113G covering the upper and side surfaces of the conductive layer 112G, a common layer 114 on the EL layer 113G, and a common electrode 115 on the common layer 114. The conductive layer 111G and the conductive layer 112G form a pixel electrode of the light-emitting element 130G. Note that in the light-emitting element 130G, the EL layer 113G and the common layer 114 can be collectively referred to as an EL layer.

[0090] The light-emitting element 130B has a conductive layer 111B on the plug 106 and on the insulating layer 105, a conductive layer 112B covering the upper and side surfaces of the conductive layer 111B, an EL layer 113B covering the upper and side surfaces of the conductive layer 112B, a common layer 114 on the EL layer 113B, and a common electrode 115 on the common layer 114. Here, the conductive layer 111B and the conductive layer 112B form a pixel electrode of the light-emitting element 130B. Note that in the light-emitting element 130B, the EL layer 113B and the common layer 114 can also be collectively referred to as an EL layer.

[0091] One of the pixel electrode and the common electrode of the light-emitting element functions as an anode, and the other functions as a cathode. In the following, unless otherwise specified, the pixel electrode may function as an anode and the common electrode may function as a cathode.

[0092] The EL layer 113R, the EL layer 113G, and the EL layer 113B each have at least a light-emitting layer. For example, the EL layer 113R may have a light-emitting layer that emits red light, the EL layer 113G may have a light-emitting layer that emits green light, and the EL layer 113B may have a light-emitting layer that emits blue light. The EL layer 113R, the EL layer 113G, or the EL layer 113B may emit light of cyan, magenta, yellow, white, infrared, or the like.

[0093] The EL layer 113R, the EL layer 113G, and the EL layer 113B are spaced apart from one another. By providing the EL layer 113 in an island shape for each light-emitting element 130, leakage current between adjacent light-emitting elements 130 can be suppressed. This makes it possible to suppress crosstalk caused by unintended light emission, and realize a display device with extremely high contrast. In particular, a display device with high current efficiency at low luminance can be realized.

[0094] The island-shaped EL layer 113 can be formed by depositing an EL film and processing the EL film using, for example, photolithography. For example, the EL layer 113R can be formed by depositing and processing an EL film that becomes the EL layer 113R, the EL layer 113G can be formed by depositing and processing an EL film that becomes the EL layer 113G, and the EL layer 113B can be formed by depositing and processing an EL film that becomes the EL layer 113B.

[0095] The EL layer 113 is provided so as to cover the top and side surfaces of the pixel electrode of the light-emitting element 130. This makes it easier to increase the aperture ratio of the display device 100 compared to a configuration in which the end of the EL layer 113 is located inside the end of the pixel electrode. Furthermore, covering the side surfaces of the pixel electrode of the light-emitting element 130 with the EL layer 113 prevents the pixel electrode from contacting the common electrode 115, thereby preventing short circuits in the light-emitting element 130. Furthermore, the distance between the light-emitting region of the EL layer 113, i.e., the region where the pixel electrode, the EL layer 113, and the common electrode 115 overlap, and the end of the EL layer 113 can be increased. Because the end of the EL layer 113 may be damaged by processing, using a region away from the end of the EL layer 113 as the light-emitting region may improve the reliability of the light-emitting element 130.

[0096] In addition, in a display device according to one embodiment of the present invention, the pixel electrode of the light-emitting element has a stacked structure of multiple layers. For example, in the example shown in FIG. 2A , the pixel electrode of the light-emitting element 130 has a stacked structure of a conductive layer 111 and a conductive layer 112. For example, when the display device 100 is a top-emission type and the pixel electrode of the light-emitting element 130 functions as an anode, the conductive layer 111 can have a higher reflectivity for visible light than the conductive layer 112, and the conductive layer 112 can have a higher work function than the conductive layer 111. The higher the reflectivity of the pixel electrode for visible light, the more effectively light emitted from the EL layer 113 can be prevented from passing through the pixel electrode. Therefore, when the display device 100 is a top-emission type, the light extraction efficiency of the EL layer 113 can be increased. Furthermore, when the pixel electrode functions as an anode, the higher the work function of the pixel electrode, the easier it is to inject holes into the EL layer 113, thereby reducing the driving voltage of the light-emitting element. As described above, by forming the pixel electrode of the light-emitting element 130 into a stacked structure of the conductive layer 111 having a high reflectivity for visible light and the conductive layer 112 having a high work function, the light-emitting element 130 can be a light-emitting element with high light extraction efficiency and low driving voltage.

[0097] When the conductive layer 111 has a higher reflectivity to visible light than the conductive layer 112, the reflectivity of the conductive layer 111 to visible light is, for example, preferably 40% to 100%, more preferably 70% to 100%. The conductive layer 112 can be an electrode that is transparent to visible light (also referred to as a transparent electrode).

[0098] In this specification and the like, a transparent electrode refers to an electrode having a transmittance of 40% or more for visible light.

[0099] The conductive layer 111 of the light-emitting element 130 is a layer having high reflectivity with respect to light emitted by the EL layer 113. For example, when the EL layer 113 emits infrared light, the conductive layer 111 can be a layer having high reflectivity with respect to infrared light. When the pixel electrode of the light-emitting element 130 functions as a cathode, the conductive layer 112 can be a layer having a work function smaller than that of the conductive layer 111, for example.

[0100] On the other hand, when the pixel electrode has a stacked structure of multiple layers, the pixel electrode may be altered, for example, due to a reaction between the multiple layers. For example, as will be described in detail later, when a film formed after the formation of the pixel electrode is removed by a wet etching method in the manufacture of the display device 100, a chemical solution may come into contact with the pixel electrode. When the pixel electrode has a stacked structure of multiple layers, galvanic corrosion may occur due to the contact of the multiple layers with the chemical solution. This may cause alteration of at least one of the layers constituting the pixel electrode. This may result in a decrease in the yield of the display device. Furthermore, the reliability of the display device may be reduced.

[0101] Therefore, in the display device 100, the conductive layer 112 is formed so as to cover the upper surface and side surfaces of the conductive layer 111. This prevents a chemical solution from coming into contact with the conductive layer 111, even when a film formed after forming a pixel electrode having the conductive layer 111 and the conductive layer 112 is removed by wet etching, for example. This prevents, for example, galvanic corrosion from occurring in the pixel electrode. Therefore, the display device 100 can be manufactured by a method with a high yield. Furthermore, since defects in the display device 100 can be prevented, the display device 100 can be a highly reliable display device.

[0102] The conductive layer 111 can be formed using, for example, a metal material. Examples of the metal 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), or an alloy containing an appropriate combination of these metals. Examples of alloy materials that can be used include aluminum-containing alloys (aluminum alloys) such as an aluminum-nickel-lanthanum alloy (Al-Ni-La), and silver-magnesium alloys or silver-palladium-copper alloys (Ag-Pd-Cu, also referred to as APC).

[0103] The conductive layer 112 can be made of an oxide containing one or more selected from indium, tin, zinc, gallium, titanium, aluminum, and silicon. For example, it is preferable to use a conductive oxide containing one or more of indium oxide, indium tin oxide, indium zinc oxide, zinc oxide, zinc oxide containing gallium, titanium oxide, indium titanium oxide, zinc titanate, aluminum zinc oxide, indium zinc oxide containing gallium, indium zinc oxide containing aluminum, indium tin oxide containing silicon, and indium zinc oxide containing silicon. In particular, indium tin oxide containing silicon has a large work function, for example, a work function of 4.0 eV or more, and therefore can be suitably used for the conductive layer 112 when the pixel electrode functions as an anode.

[0104] Note that, as will be described in detail later, the conductive layer 111 may have a stacked structure of multiple layers containing different materials, and the conductive layer 112 may have a stacked structure of multiple layers containing different materials. In this case, the conductive layer 111 may have a layer using a material that can be used for the conductive layer 112, such as a conductive oxide. Alternatively, the conductive layer 112 may have a layer using a material that can be used for the conductive layer 111, such as a metal material. For example, when the conductive layer 112 has a stacked structure of two or more layers, the layer in contact with the conductive layer 111 can be a layer using a material that can be used for the conductive layer 111, such as a metal material.

[0105] Here, the end portion of the conductive layer 111 can have a tapered shape. Specifically, the end portion of the conductive layer 111 preferably has a tapered shape with a taper angle of less than 90°. In this case, the conductive layer 112 provided along the side surface of the conductive layer 111 also has a tapered shape. Therefore, the EL layer 113 provided along the side surface of the conductive layer 112 also has a tapered shape. By tapering the side surface of the conductive layer 112, the coverage of the EL layer 113 provided along the side surface of the conductive layer 112 can be improved.

[0106] In FIG. 2A , an insulating layer (also referred to as a bank or a structure) covering the upper end of the conductive layer 112R is not provided between the conductive layer 112R and the EL layer 113R. Furthermore, an insulating layer covering the upper end of the conductive layer 112G is not provided between the conductive layer 112G and the EL layer 113G. Furthermore, an insulating layer covering the upper end of the conductive layer 112B is not provided between the conductive layer 112B and the EL layer 113B. This allows the distance between adjacent light-emitting elements 130 to be extremely narrow. This allows for a high-definition or high-resolution display device. Furthermore, a mask for forming the insulating layer is not required, thereby reducing the manufacturing cost of the display device.

[0107] Furthermore, by not providing an insulating layer covering the end portions of the conductive layer 112 between the conductive layer 112 and the EL layer 113, light emitted from the EL layer 113 can be efficiently extracted. Therefore, the display device 100 can have extremely low viewing angle dependency. By reducing the viewing angle dependency, the visibility of images in the display device 100 can be improved. For example, the viewing angle (the maximum angle at which a certain contrast ratio is maintained when the screen is viewed from an oblique direction) of the display device 100 can be set to a range of 100° or more and less than 180°, preferably 150° or more and 170° or less. Note that the above viewing angle can be applied to both the top and bottom and the left and right.

[0108] The insulating layer 101, the insulating layer 103, and the insulating layer 105 function as interlayer insulating layers. As the insulating layer 101, the insulating layer 103, and the insulating layer 105, various inorganic insulating films such as an oxide insulating film, a nitride insulating film, an oxynitride insulating film, or a nitride oxide insulating film can be suitably used. Specifically, for example, a silicon oxide film, a silicon oxynitride film, an aluminum oxide film, a silicon nitride film, or a silicon nitride oxide film can be used.

[0109] 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.

[0110] The insulating layer 104 functions as a barrier layer that prevents impurities such as water from entering the light-emitting element 130. As the insulating layer 104, for example, a film through which hydrogen or oxygen is less likely to diffuse than a silicon oxide film, such as a silicon nitride film, an aluminum oxide film, or a hafnium oxide film, can be used.

[0111] The film thickness of the insulating layer 105 in the region not overlapping with the conductive layer 111 may be thinner than the film thickness of the insulating layer 105 in the region overlapping with the conductive layer 111. In other words, the insulating layer 105 may have a recess in the region not overlapping with the conductive layer 111. The recess is formed, for example, due to the process of forming the conductive layer 111.

[0112] The conductive layer 102 functions as a wiring and is electrically connected to the light-emitting element 130 via a plug 106 .

[0113] Various conductive materials can be used for the conductive layer 102 and the plug 106, such as metals such as aluminum (Al), magnesium (Mg), titanium (Ti), chromium (Cr), nickel (Ni), copper (Cu), yttrium (Y), zirconium (Zr), tin (Sn), zinc (Zn), silver (Ag), platinum (Pt), gold (Au), molybdenum (Mo), tantalum (Ta), or tungsten (W), or alloys containing these as main components (such as APC). Alternatively, oxides such as tin oxide or zinc oxide may be used for the conductive layer 102 and the plug 106.

[0114] The light emitting element 130 can have a single structure (a structure having only one light emitting unit).

[0115] As described above, the EL layer 113R, the EL layer 113G, and the EL layer 113B each have at least a light-emitting layer. For example, the EL layer 113R may have a light-emitting layer that emits red light, the EL layer 113G may have a light-emitting layer that emits green light, and the EL layer 113B may have a light-emitting layer that emits blue light.

[0116] Each of the EL layer 113R, the EL layer 113G, and the EL layer 113B may include one or more of a hole injection layer, a hole transport layer, a hole blocking layer, a charge generation layer (also referred to as an intermediate layer), an electron blocking layer, an electron transport layer, and an electron injection layer.

[0117] In this specification and the like, layers other than the light-emitting layer among the layers included in the EL layer are referred to as functional layers.

[0118] For example, when the pixel electrode of the light-emitting element 130 functions as an anode and the common electrode 115 functions as a cathode, the EL layer 113R, EL layer 113G, and EL layer 113B may have a hole injection layer, a hole transport layer, an emitting layer, and an electron transport layer in this order. That is, the EL layer 113 may have a configuration in which, for example, from bottom to top, a first functional layer having a hole injection layer and a hole transport layer, a emitting layer, and a second functional layer having an electron transport layer are stacked. An electron blocking layer may be provided between the hole transport layer and the emitting layer. A hole blocking layer may be provided between the electron transport layer and the emitting layer. An electron injection layer may be provided on the electron transport layer. The first functional layer may have either a hole injection layer or a hole transport layer, but not the other. The second functional layer may have an electron injection layer or may not have an electron transport layer.

[0119] Furthermore, for example, when the pixel electrode of the light-emitting element 130 functions as a cathode and the common electrode 115 functions as an anode, the EL layer 113R, the EL layer 113G, and the EL layer 113B may have an electron injection layer, an electron transport layer, an emitting layer, and a hole transport layer in this order. That is, the EL layer 113 may have a configuration in which, for example, from bottom to top, a first functional layer having an electron injection layer and an electron transport layer, a emitting layer, and a second functional layer having a hole transport layer are stacked. A hole blocking layer may be provided between the electron transport layer and the emitting layer. An electron blocking layer may be provided between the hole transport layer and the emitting layer. A hole injection layer may be provided on the hole transport layer. The first functional layer may have either an electron injection layer or an electron transport layer, but not the other. The second functional layer may have a hole injection layer or may not have a hole transport layer.

[0120] As described above, the EL layer 113R, the EL layer 113G, and the EL layer 113B preferably have a light-emitting layer and a carrier transport layer on the light-emitting layer. The EL layer 113R, the EL layer 113G, and the EL layer 113B preferably have a light-emitting layer and a carrier block layer on the light-emitting layer. The EL layer 113R, the EL layer 113G, and the EL layer 113B preferably have a light-emitting layer, a carrier block layer on the light-emitting layer, and a carrier transport layer on the carrier block layer. The surfaces of the EL layer 113R, the EL layer 113G, and the EL layer 113B are exposed during the manufacturing process of the display device. Therefore, by providing one or both of the carrier transport layer and the carrier block layer on the light-emitting layer, the light-emitting layer can be prevented from being exposed to the outermost surface, thereby reducing damage to the light-emitting layer. This improves the reliability of the light-emitting element.

[0121] The heat resistance temperature of the compounds contained in EL layer 113R, EL layer 113G, and EL layer 113B is preferably 100° C. or higher and 180° C. or lower, more preferably 120° C. or higher and 180° C. or lower, and even more preferably 140° C. or higher and 180° C. or lower. For example, the glass transition point (Tg) of these compounds is preferably 100° C. or higher and 180° C. or lower, more preferably 120° C. or higher and 180° C. or lower, and even more preferably 140° C. or higher and 180° C. or lower.

[0122] In particular, it is preferable that the heat resistance temperature of the functional layer provided on the light-emitting layer is high. Furthermore, it is even more preferable that the heat resistance temperature of the functional layer provided on and in contact with the light-emitting layer is high. The high heat resistance of the functional layer makes it possible to effectively protect the light-emitting layer and reduce damage to the light-emitting layer.

[0123] The functional layer provided on the light-emitting layer is preferably an organic compound having a bicarbazole skeleton and a heteroaromatic ring skeleton containing one selected from a pyridine ring, a diazine ring, and a triazine ring, or an organic compound having a bicarbazole skeleton and a fused heteroaromatic ring skeleton containing a pyridine ring or a diazine ring, and the Tg is preferably 100°C or higher and 180°C or lower, preferably 120°C or higher and 180°C or lower, and more preferably 140°C or higher and 180°C or lower. The functional layer using such an organic compound can function as a hole-blocking layer or an electron-transporting layer, or both. The functional layer using such an organic compound is not limited to being located above the light-emitting layer (on the upper electrode side), but may also be located below the light-emitting layer (on the lower electrode side).

[0124] Specific examples of such organic compounds include 2-{3-[3-(9-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}dibenzo[f,h]quinoxaline (abbreviation: 2mPCCzPDBq), 2-{3-[2-(9-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}dibenzo[f,h]quinoxaline (abbreviation: 2mPCCzPDBq-02), 9-[3-(4,6-diphenyl-1,3 ,5-triazin-2-yl)phenyl]-9'-phenyl-3,3'-bi-9H-carbazole (abbreviation: mPCCzPTzn), 9-[3-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-9'-phenyl-2,3'-bi-9H-carbazole (abbreviation: mPCCzPTzn-02), 9-[4-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-9'-phenyl-3,3'-bi-9H-carbazole (abbreviation: P CCzPTzn), 9-(4,6-diphenyl-1,3,5-triazin-2-yl)-9'-phenyl-3,3'-bi-9H-carbazole (abbreviation: PCCzTzn), 9-[3-(4,6-diphenyl-pyrimidin-2-yl)phenyl]-9'-phenyl-3,3'-bi-9H-carbazole (abbreviation: 2PCCzPPm), 9-(4,6-diphenyl-pyrimidin-2-yl)-9'-phenyl-2,3'-bi-9H-carbazole (abbreviation: 2PCCzPm ), 9-(4,6-diphenylpyrimidin-2-yl)-9'-phenyl-3,3'-bi-9H-carbazole (abbreviation: 2PCCzPm-02), 4-(9'-phenyl[2,3'-bi-9H-carbazole]-9-yl)benzofuro[3,2-d]pyrimidine (abbreviation: 4PCCzBfpm-02), and 4-{3-[3-(9-phenyl-9H-carbazole-3-yl)-9H-carbazole-9-yl]phenyl}benzo[h]quinazoline, etc.

[0125] Furthermore, it is preferable that the light-emitting layer has a high heat resistance temperature, which can prevent the light-emitting layer from being damaged by heating, resulting in a decrease in light-emitting efficiency and a shortened lifespan.

[0126] The EL layer 113R, the EL layer 113G, and the EL layer 113B can each have, for example, a first light-emitting unit, a charge generation layer, and a second light-emitting unit.

[0127] The second light-emitting unit preferably has an emitting layer and a carrier transport layer on the emitting layer. The second light-emitting unit preferably has an emitting layer and a carrier block layer on the emitting layer. The second light-emitting unit preferably has an emitting layer, a carrier block layer on the emitting layer, and a carrier transport layer on the carrier block layer. The surface of the second light-emitting unit is exposed during the manufacturing process of the display device. Therefore, by providing one or both of the carrier transport layer and the carrier block layer on the emitting layer, the emitting layer is prevented from being exposed on the outermost surface, thereby reducing damage to the emitting layer. This improves the reliability of the light-emitting element. When three or more emitting units are included, the uppermost emitting unit preferably has an emitting layer and one or both of the carrier transport layer and the carrier block layer on the emitting layer.

[0128] When the pixel electrode of the light-emitting element 130 functions as an anode and the common electrode 115 functions as a cathode, the common layer 114 has at least one of an electron injection layer or an electron transport layer, for example, an electron injection layer. Alternatively, the common layer 114 may have a stack of an electron transport layer and an electron injection layer. On the other hand, when the pixel electrode of the light-emitting element 130 functions as a cathode and the common electrode 115 functions as an anode, the common layer 114 has at least one of a hole injection layer or a hole transport layer, for example, a hole injection layer. Alternatively, the common layer 114 may have a stack of a hole transport layer and a hole injection layer. The common layer 114 is shared by the light-emitting element 130R, the light-emitting element 130G, and the light-emitting element 130B.

[0129] Similarly to the common layer 114, the common electrode 115 is also shared by the light emitting elements 130R, 130G, and 130B.

[0130] The common electrode 115 can be formed continuously after the common layer 114 is formed, without any intervening process such as etching. For example, after forming the common layer 114 in a vacuum, the common electrode 115 can be formed in a vacuum without removing the substrate into the atmosphere. In other words, the common layer 114 and the common electrode 115 can be formed in a vacuum. This allows the lower surface of the common electrode 115 to be cleaner than when the display device 100 does not include the common layer 114. Therefore, the light-emitting element 130 can be a light-emitting element with high reliability and excellent characteristics.

[0131] In the example shown in FIG. 2A , a mask layer 118R is provided on the EL layer 113R of the light-emitting element 130R, a mask layer 118G is provided on the EL layer 113G of the light-emitting element 130G, and a mask layer 118B is provided on the EL layer 113B of the light-emitting element 130B. The mask layer 118R is a mask layer that was provided on the upper surface of the EL layer 113R when processing the EL layer 113R, with a portion of the mask layer remaining. Similarly, the mask layer 118G is a mask layer that was provided when the EL layer 113G was formed, and the mask layer 118B is a mask layer that was provided when the EL layer 113B was formed, with a portion of the mask layer remaining. In this way, the display device 100 may have a mask layer used to protect the EL layer during its fabrication that is partially remaining. The same material may be used for any two or all of the mask layers 118R, 118G, and 118B, or different materials may be used. In the following description, the mask layer 118R, the mask layer 118G, and the mask layer 118B may be collectively referred to as the mask layer 118.

[0132] 2A , one end of the mask layer 118R is aligned or approximately aligned with an end of the EL layer 113R, and the other end of the mask layer 118R is located on the EL layer 113R. Here, it is preferable that the other end of the mask layer 118R overlaps with the conductive layer 111R. In this case, the other end of the mask layer 118R is easily formed on a substantially flat surface of the EL layer 113R. The same applies to the mask layers 118G and 118B. Furthermore, the mask layer 118 remains, for example, between the upper surface of the EL layer 113, which has been processed into an island shape, and the insulating layer 125.

[0133] In addition, when the edges are aligned or approximately aligned, and when the top surface shapes are the same or approximately aligned, it can be said that at least a portion of the contours of the stacked layers overlap in a planar view. The case where at least a portion of the contours of the upper and lower layers overlap includes, for example, a case where the upper and lower layers are processed using the same mask pattern or a case where the upper and lower layers are processed using the same mask pattern. However, strictly speaking, the contours may not overlap, and the upper layer may be located inside the lower layer, or outside the lower layer. In this case, it can also be said that the edges are approximately aligned, or the top surface shapes are approximately aligned.

[0134] The side surfaces of the EL layer 113R, the EL layer 113G, and the EL layer 113B are covered with the insulating layer 125. The insulating layer 127 overlaps the side surfaces of the EL layer 113R, the EL layer 113G, and the EL layer 113B with the insulating layer 125 interposed therebetween.

[0135] Furthermore, a portion of the upper surface of each of the EL layers 113R, 113G, and 113B is covered with a mask layer 118. The insulating layers 125 and 127 overlap a portion of the upper surface of each of the EL layers 113R, 113G, and 113B via the mask layer 118.

[0136] By covering part of the top surface and the side surfaces of the EL layer 113R, the EL layer 113G, and the EL layer 113B with at least one of the insulating layer 125, the insulating layer 127, and the mask layer 118, the common layer 114 and the common electrode 115 are prevented from contacting the side surfaces of the EL layer 113R, the EL layer 113G, and the EL layer 113B, thereby preventing short circuits of the light-emitting element 130. This improves the reliability of the light-emitting element 130.

[0137] The EL layers 113R, 113G, and 113B may have different film thicknesses. For example, it is preferable to set the film thicknesses in accordance with the optical path lengths that intensify the light emitted by the EL layers 113R, 113G, and 113B. This realizes a micro-optical resonator (microcavity) structure, and can improve the color purity of the light emitted from the subpixel 110.

[0138] The insulating layer 125 preferably contacts the side surfaces of the EL layer 113R, EL layer 113G, and EL layer 113B. This can prevent the EL layer 113R, EL layer 113G, and EL layer 113B from peeling off. The insulating layer 125 and the EL layer 113R, EL layer 113G, or EL layer 113B are in close contact with each other, which has the effect of fixing or bonding adjacent EL layers 113 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 can be increased.

[0139] 2A , the insulating layer 125 and the insulating layer 127 cover part of the top surface and both the side surfaces of the EL layer 113R, the EL layer 113G, and the EL layer 113B, which can more suitably suppress film peeling of the EL layer 113 and more suitably improve the reliability of the light-emitting element 130. In addition, the manufacturing yield of the light-emitting element 130 can be more suitably improved.

[0140] 2A shows an example in which a stacked structure of an EL layer 113R, a mask layer 118R, an insulating layer 125, and an insulating layer 127 is located on an end of the conductive layer 112R. Similarly, a stacked structure of an EL layer 113G, a mask layer 118G, an insulating layer 125, and an insulating layer 127 is located on an end of the conductive layer 112G, and a stacked structure of an EL layer 113B, a mask layer 118B, an insulating layer 125, and an insulating layer 127 is located on an end of the conductive layer 112B.

[0141] 2A shows a configuration in which the end portion of the conductive layer 112R is covered with the EL layer 113R, and the insulating layer 125 has a region in contact with the side surface of the EL layer 113R. Similarly, the end portion of the conductive layer 112G is covered with the EL layer 113G, the end portion of the conductive layer 112B is covered with the EL layer 113B, and the insulating layer 125 has a region in contact with the side surface of the EL layer 113G and the side surface of the EL layer 113B.

[0142] The insulating layer 127 is provided on the insulating layer 125 so as to fill recesses formed in the insulating layer 125. The insulating layer 127 can be configured to overlap with part of the top surface and side surfaces of the EL layer 113R, the EL layer 113G, and the EL layer 113B via the insulating layer 125. The insulating layer 127 preferably covers at least part of the side surface of the insulating layer 125.

[0143] By providing the insulating layers 125 and 127, the gaps between adjacent island-shaped layers can be filled, and therefore, the formation surfaces of the layers provided on the island-shaped layers, specifically, the formation surfaces of the common layer 114, the common electrode 115, etc., can be reduced in extreme unevenness and made flatter. Therefore, the coverage of the common layer 114, the common electrode 115, etc. can be improved.

[0144] The common layer 114 and common electrode 115 are provided on the EL layer 113R, the EL layer 113G, the EL layer 113B, the mask layer 118, the insulating layer 125, and the insulating layer 127. Before the insulating layer 125 and the insulating layer 127 are provided, a step exists between the area where the pixel electrode and the island-shaped EL layer 113 are provided and the area where the pixel electrode and the island-shaped EL layer 113 are not provided (the area between the light-emitting elements 130). The display device 100 includes the insulating layer 125 and the insulating layer 127, which can flatten the step and improve the coverage of the common layer 114 and the common electrode 115. This can prevent connection failures due to step disconnections. Furthermore, the step can prevent the common electrode 115 from becoming locally thin and increasing electrical resistance.

[0145] The upper surface of the insulating layer 127 preferably has a highly flat shape, but may have a convex portion, a convex curved surface, a concave curved surface, or a concave portion. For example, the upper surface of the insulating layer 127 preferably has a highly flat, smooth convex curved surface shape.

[0146] In the display device 100, an insulating layer 127 is provided on the insulating layer 125 so as to fill recesses formed in the insulating layer 125. The insulating layer 127 is also provided between the island-shaped EL layers 113. In other words, the display device 100 employs a process (hereinafter referred to as process 1) in which the island-shaped EL layers 113 are formed and then the insulating layer 127 is provided so as to overlap the edges of the island-shaped EL layers 113. On the other hand, a process different from process 1 is a process (hereinafter referred to as process 2) in which pixel electrodes are formed in an island shape, an insulating layer is formed to cover the edges of the pixel electrodes, and then the pixel electrodes and the island-shaped EL layers 113 are formed on the insulating layer.

[0147] The above-mentioned Process 1 is preferable because it can provide a wider margin than the above-mentioned Process 2. More specifically, the above-mentioned Process 1 has a wider margin for alignment accuracy between different patternings than the above-mentioned Process 2, and can provide a display device with less variation in characteristics. The manufacturing method of the display device 100 is based on the above-mentioned Process 1, and therefore can provide a display device with less variation and high display quality.

[0148] Next, examples of materials for the insulating layer 125 and the insulating layer 127 will be described.

[0149] The insulating layer 125 can be an insulating layer containing an inorganic material. For example, an inorganic insulating film such as an insulating oxide film, a nitride insulating film, an oxynitride insulating film, or a nitride oxide insulating film can be used for the insulating layer 125. The insulating layer 125 may have a single-layer structure or a stacked-layer structure. Examples of oxide insulating films include a silicon oxide film, an aluminum oxide film, a magnesium oxide film, an indium gallium zinc oxide film, a gallium oxide film, a germanium oxide film, an yttrium oxide film, a zirconium oxide film, a lanthanum oxide film, a neodymium oxide film, a hafnium oxide film, and a tantalum oxide film. Examples of nitride insulating films include a silicon nitride film and an aluminum nitride film. Examples of oxynitride insulating films include a silicon oxynitride film and an aluminum oxynitride film. Examples of nitride oxide insulating films include a silicon nitride oxide film and an aluminum nitride oxide film. In particular, aluminum oxide is preferable because it has a high etching selectivity with respect to the EL layer 113 and has a function of protecting the EL layer 113 in the formation of the insulating layer 127 described later. In particular, by using an inorganic insulating film such as an aluminum oxide film, a hafnium oxide film, or a silicon oxide film formed by atomic layer deposition (ALD) as the insulating layer 125, it is possible to form an insulating layer 125 that has few pinholes and has an excellent function of protecting the EL layer 113. The insulating layer 125 may also have a stacked structure of a film formed by ALD and a film formed by sputtering. For example, the insulating layer 125 may have a stacked structure of an aluminum oxide film formed by ALD and a silicon nitride film formed by sputtering.

[0150] 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.

[0151] 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 a corresponding substance.

[0152] The insulating layer 125 has a function as a barrier insulating layer or a gettering function, which can suppress the entry of impurities, typically at least one of water and oxygen, which may diffuse from the outside into the light-emitting element 130. With this structure, a highly reliable light-emitting element and further a highly reliable display device can be provided.

[0153] The insulating layer 125 preferably has a low impurity concentration. This can prevent impurities from entering the EL layer 113 from the insulating layer 125 and causing deterioration of the EL layer 113. Furthermore, a low impurity concentration in the insulating layer 125 can improve 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.

[0154] The insulating layer 125 and the mask layers 118R, 118G, and 118B may be made of the same material. In this case, the boundary between the insulating layer 125 and any of the mask layers 118R, 118G, and 118B may become unclear and indistinguishable. Therefore, the insulating layer 125 and any of the mask layers 118R, 118G, and 118B may be recognized as a single layer. In other words, a single layer may be provided in contact with a portion of the top surface and the side surface of each of the EL layers 113R, 113G, and 113B, and the insulating layer 127 may be observed to cover at least a portion of the side surface of the single layer.

[0155] The insulating layer 127 provided on the insulating layer 125 has the function of flattening the extreme irregularities of the insulating layer 125 formed between adjacent light-emitting elements 130. In other words, the presence of the insulating layer 127 has the effect of improving the flatness of the surface on which the common electrode 115 is formed.

[0156] An insulating layer containing an organic material can be suitably used as the insulating layer 127. As the organic material, a photosensitive material, for example, a photosensitive organic resin, is preferably used, and a photosensitive resin composition containing an acrylic resin is preferably used. Note that in this specification and the like, the term "acrylic resin" does not refer only to polymethacrylic acid ester or methacrylic resin, but may refer to all acrylic polymers in a broad sense.

[0157] The insulating layer 127 may be made of an acrylic resin, a polyimide resin, an epoxy resin, an imide resin, a polyamide resin, a polyimideamide resin, a silicone resin, a siloxane resin, a benzocyclobutene-based resin, a phenolic resin, or a precursor of any of these resins. The insulating layer 127 may be made of an organic material such as polyvinyl alcohol (PVA), polyvinyl butyral, polyvinylpyrrolidone, polyethylene glycol, polyglycerin, pullulan, water-soluble cellulose, or an alcohol-soluble polyamide resin. The photosensitive resin may be a photoresist. Either a positive-type material or a negative-type material may be used as the photosensitive organic resin.

[0158] 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 improves 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.

[0159] Examples of materials that absorb visible light include materials containing pigments such as black, materials containing dyes, resin materials with light absorption properties such as polyimide, and resin materials (color filter materials) that can be used for colored layers. 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 obtain a black or nearly black resin layer.

[0160] Furthermore, it is preferable that the material used for the insulating layer 127 has a low volumetric shrinkage rate. This makes it easy to form the insulating layer 127 in a desired shape. It is also preferable that the insulating layer 127 has a low volumetric shrinkage rate after curing. This makes it easier to maintain the shape of the insulating layer 127 in various processes after its formation. Specifically, the volumetric shrinkage rate of the insulating layer 127 after thermal curing, after photocuring, or after photocuring and thermal curing is preferably 10% or less, more preferably 5% or less, and even more preferably 1% or less. Here, the volumetric shrinkage rate can be either one of the volumetric shrinkage rate due to light irradiation and the volumetric shrinkage rate due to heating, or the sum of both.

[0161] Providing the protective layer 131 over the light-emitting element 130 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.

[0162] 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.

[0163] For the protective layer 131, an inorganic insulating film such as an insulating oxide film, an insulating nitride film, an insulating oxynitride film, or an insulating nitride oxide film can be used. Specific examples of these inorganic insulating films are as mentioned in the description of the insulating layer 125. In particular, the protective layer 131 preferably includes an insulating nitride film or an insulating nitride oxide film, and more preferably includes an insulating nitride film.

[0164] 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.

[0165] The protective layer 131 having an inorganic film can suppress oxidation of the common electrode 115. Furthermore, the protective layer 131 having an inorganic film can suppress impurities such as water and oxygen from entering the light-emitting element 130. As a result, the light-emitting element 130 can be made to be a light-emitting element that is resistant to deterioration, and the display device 100 can be made to be a highly reliable display device.

[0166] When light emitted from the light-emitting element 130 is extracted through the protective layer 131, it is preferable that the protective layer 131 have high transparency to visible light. For example, ITO, IGZO, and aluminum oxide are preferable because they are inorganic materials that have high transparency to visible light.

[0167] The protective layer 131 may have, 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. By using such a stacked structure, impurities such as water and oxygen can be prevented from entering the EL layer 113.

[0168] 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.

[0169] The protective layer 131 may have a two-layer structure formed by using different film formation methods. Specifically, the first layer of the protective layer 131 may be formed by the ALD method, and the second layer of the protective layer 131 may be formed by the sputtering method.

[0170] A light-shielding layer may be provided on the surface of the substrate 120 facing the resin 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 such as a diffusion film, an anti-reflection layer, and a light-collecting film. Furthermore, 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 may be disposed on the outside of the substrate 120. 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 of the display device. A substrate having high optical isotropy has small birefringence, specifically, a 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. For this reason, 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 resin layer 122 can be made of various curable adhesives, such as a photo-curable adhesive (e.g., an ultraviolet-curable adhesive), a reactive curable adhesive, a thermosetting adhesive, or an anaerobic adhesive. Examples of such adhesives include epoxy resin, acrylic resin, silicone resin, phenolic resin, polyimide resin, imide resin, PVC (polyvinyl chloride) resin, PVB (polyvinyl butyral) resin, and EVA (ethylene vinyl acetate) resin. 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, for example.

[0178] 2B1 is a cross-sectional view showing a structural example of the conductive layer 111 and the conductive layer 112. Note that Fig. 2B1 also shows the insulating layer 105. The same applies to other drawings showing structural examples of the conductive layer 111 and the conductive layer 112.

[0179] 2B1, the conductive layer 111 can have a structure including a conductive layer 111a over the insulating layer 105, a conductive layer 111b over the conductive layer 111a, and a conductive layer 111c over the conductive layer 111b. In addition, a conductive layer 112 is provided so as to cover the top surface of the conductive layer 111c, the side surfaces of the conductive layer 111c, the side surfaces of the conductive layer 111b, and the side surfaces of the conductive layer 111a.

[0180] 2B1, the conductive layer 111b is sandwiched between the conductive layer 111a and the conductive layer 111c. The conductive layer 111a and the conductive layer 111c can be made of a material that is less susceptible to deterioration than the conductive layer 111b. For example, the conductive layer 111a can be made of a material that is less susceptible to migration due to contact with the insulating layer 105 than the conductive layer 111b. The conductive layer 111c can be made of a material that is less susceptible to oxidation than the conductive layer 111b and has an oxide with a lower electrical resistivity than the oxide of the material used for the conductive layer 111b.

[0181] In this specification, migration refers to one or both of stress migration and electromigration. Stress migration refers to a phenomenon in which atoms contained in a conductive layer migrate due to stress generated in the conductive layer during heat treatment caused by a difference in the thermal expansion coefficient between the conductive layer and a layer such as an insulating layer in contact with the conductive layer. Electromigration refers to a phenomenon in which atoms contained in a conductive layer migrate due to an electric field. Migration can cause hillocks, which are protrusions on the surface, or voids, which are cavities, to form in the conductive layer. The formation of hillocks can cause the conductive layer to short-circuit with other conductive layers, and the formation of voids can cause the conductive layer to split.

[0182] As described above, by sandwiching the conductive layer 111b between the conductive layer 111a and the conductive layer 111c, the range of materials that can be selected for the conductive layer 111b can be expanded. This allows the conductive layer 111b to have a higher reflectivity for visible light than at least one of the conductive layer 111a and the conductive layer 111c. For example, aluminum can be used for the conductive layer 111b. An alloy containing aluminum may also be used for the conductive layer 111b. Furthermore, titanium, which has a lower reflectivity for visible light than aluminum but is less likely to migrate than aluminum even when in contact with the insulating layer 105, can be used for the conductive layer 111a. Furthermore, titanium, which has a lower reflectivity for visible light than aluminum but is less likely to oxidize than aluminum and has an oxide with lower electrical resistivity than aluminum oxide, can be used for the conductive layer 111c.

[0183] As described above, by forming the conductive layer 111 into a stacked structure of a plurality of layers, the characteristics of the display device can be improved. For example, the display device 100 can be a display device with high light extraction efficiency and high reliability.

[0184] FIG. 2B2 is a modified example of the configuration shown in FIG. 2B1, and shows an example in which the conductive layer 112 has a conductive layer 112a covering the top surface of the conductive layer 111c, the side surface of the conductive layer 111c, the side surface of the conductive layer 111b, and the side surface of the conductive layer 111a, and a conductive layer 112b on the conductive layer 112a.

[0185] The conductive layer 112a can be made of a material similar to that used for the conductive layer 111c. The conductive layer 112b can be made of a material similar to that used for the conductive layer 112 shown in FIG. 2B1. That is, the conductive layer 112a can be made of a metal material such as titanium, and the conductive layer 112b can be made of a conductive oxide such as indium tin oxide.

[0186] By configuring the conductive layer 112 as shown in FIG. 2B2, the conductive layer 112b, which can be made of a conductive oxide such as indium tin oxide, can be prevented from contacting the side surface of the conductive layer 111b, which can be made of, for example, aluminum. This effectively prevents the conductive layer 111b from deteriorating, thereby improving the reliability of the display device 100. Even when the conductive layer 112 has the configuration shown in FIG. 2B2, it is preferable to provide the conductive layer 111c. This prevents the upper surface of the conductive layer 111b, which has a higher reflectivity for visible light than the conductive layer 111a, from being oxidized by oxygen in the atmosphere after the formation of the conductive layer 111 and before the formation of the conductive layer 112. This prevents a decrease in the reflectivity of the conductive layer 111 for visible light. As a result, the display device 100 can be a display device with high light extraction efficiency.

[0187] When the conductive layer 112 has a stacked structure of a conductive layer 112a and a conductive layer 112b as shown in FIG. 2B2, a conductive oxide such as indium tin oxide may be used for the conductive layer 112a, and a mixed material of, for example, molybdenum oxide and an organic material may be used for the conductive layer 112b.

[0188] 2B1 and 2B2, for example, the end of the conductive layer 111b may be located inside the end of the conductive layer 111c in a cross-sectional view. In other words, the conductive layer 111c may have a region that protrudes from the conductive layer 111b in a cross-sectional view. In this case, if the conductive layer 112 is formed using a film formation method with low coverage, the protruding region may cause a discontinuity in the conductive layer 112. Furthermore, the conductive layer 112 may be locally thinned, resulting in an increase in electrical resistance.

[0189] Therefore, when the conductive layer 112 is formed by a film formation method with high coverage, it is possible to suppress the occurrence of connection defects due to step disconnection of the conductive layer 112 and an increase in electrical resistance due to local thinning of the conductive layer 112. For example, when the conductive layer 112 is formed by an ALD method, it is possible to suitably suppress the occurrence of connection defects due to step disconnection of the conductive layer 112 and an increase in electrical resistance due to local thinning of the conductive layer 112, even when the conductive layer 111c has a region that protrudes more than the conductive layer 111b.

[0190] 3A is a cross-sectional view showing an example of a structure of the conductive layer 111 and the conductive layer 112 that is different from those shown in FIGS. 2B1 and 2B2 . As shown in FIG. 3A , the conductive layer 111 can have a structure including a conductive layer 111a on the insulating layer 105 and a conductive layer 111b on the conductive layer 111a. That is, the conductive layer 111 shown in FIG. 3A has a two-layer stacked structure. When the conductive layer 111 has a stacked structure of multiple layers, the reflectivity of at least one of the layers constituting the conductive layer 111 to visible light is higher than the reflectivity of the conductive layer 112 to visible light. In addition, the conductive layer 112 is provided so as to cover the side and top surfaces of the conductive layer 111a and the conductive layer 111b.

[0191] As described above, the side surface of the conductive layer 111 preferably has a tapered shape. Specifically, the side surface of the conductive layer 111 preferably has a tapered shape with a taper angle of less than 90°. For example, in the conductive layer 111 having the structure shown in FIG. 3A , it is preferable that at least one of the side surfaces of the conductive layer 111a and the conductive layer 111b has a tapered shape. For example, it is preferable that the side surface of the conductive layer 111a has a tapered shape. Alternatively, it is preferable that both the side surface of the conductive layer 111a and the side surface of the conductive layer 111b have a tapered shape.

[0192] 3B is a modification of the structure shown in FIG. 3A, in which the conductive layer 112 has a two-layer structure of a conductive layer 112a and a conductive layer 112b over the conductive layer 112a. The conductive layer 112a can be made of the same material as that used for the conductive layer 111. The conductive layer 112b can be made of the same material as that used for the conductive layer 112 shown in FIG. 3A.

[0193] For example, silver or a silver-containing alloy can be used for the conductive layer 112a. Silver and silver-containing alloys have a characteristic of having a higher reflectivity for visible light than, for example, titanium. Furthermore, silver is less susceptible to oxidation than aluminum, which can be used for the conductive layer 111b, and the electrical resistivity of silver oxide is lower than that of aluminum oxide. As described above, by using silver or a silver-containing alloy for the conductive layer 112a, the visible light reflectivity of the pixel electrode can be suitably increased while suppressing an increase in the electrical resistance of the pixel electrode due to oxidation of the conductive layer 112a. Therefore, the display device 100 can be a display device with high light extraction efficiency and high reliability. In particular, when a microcavity structure is applied to the light-emitting element 130, it is preferable to use silver or a silver-containing alloy, which is a material with high visible light reflectivity, for the conductive layer 112a. This can suitably increase the light extraction efficiency of the display device 100.

[0194] Alternatively, titanium may be used for the conductive layer 112a. Titanium has better etching processability than silver, so that the conductive layer 112a can be easily formed by using titanium for the conductive layer 112a.

[0195] Note that the conductive layer 111 does not necessarily have to include the conductive layer 111b. That is, the conductive layer 111 can have a single-layer structure of the conductive layer 111a. For example, titanium, which can be used for the conductive layer 111a, is less susceptible to oxidation than aluminum, which can be used for the conductive layer 111b, and the electrical resistivity of titanium oxide is lower than that of aluminum oxide. Therefore, when the conductive layer 111 does not include the conductive layer 111b, the electrical resistance at the contact interface between the conductive layer 111 and the conductive layer 112 can be reduced.

[0196] 4A is a cross-sectional view showing a configuration example of the conductive layer 111 and the conductive layer 112 that is different from those shown in FIGS. 2B1, 2B2, 3A, and 3B. In the example shown in FIG. 4A, the conductive layer 111 has a single-layer structure. The conductive layer 112 has a three-layer stacked structure including a conductive layer 112a, a conductive layer 112b on the conductive layer 112a, and a conductive layer 112c on the conductive layer 112b.

[0197] 4A is made of a material that is resistant to oxidation even when in contact with the conductive layer 112a and that does not significantly increase electrical resistivity even if oxidized. For example, an alloy containing titanium can be used for the conductive layer 111. As a result, deterioration of the conductive layer 111 can be suppressed, and the display device 100 can be made into a highly reliable display device.

[0198] The conductive layer 112a shown in FIG. 4A has higher adhesion to the conductive layer 112b than the insulating layer 105, for example. A conductive oxide can be used for the conductive layer 112a, for example, an oxide containing one or more elements selected from indium, tin, zinc, gallium, titanium, aluminum, and silicon. Specifically, for example, indium tin oxide or indium tin oxide containing silicon can be used for the conductive layer 112a. This can suppress peeling of the conductive layer 112b, thereby making the display device 100 a highly reliable display device. Note that, as shown in FIG. 4A, the conductive layer 112a can be in contact with the insulating layer 105, and the conductive layer 112b can be in contact with the insulating layer 105.

[0199] The conductive layer 112b shown in FIG. 4A has a higher reflectance to visible light than the conductive layer 111, the conductive layer 112a, and the conductive layer 112c. The reflectance of the conductive layer 112b to visible light can be, for example, 70% to 100%, preferably 80% to 100%, and more preferably 90% to 100%. For example, silver or an alloy containing silver can be used as the conductive layer 112b. An example of an alloy containing silver is APC. As a result, the display device 100 can be a display device with high light extraction efficiency.

[0200] When the conductive layers 111 and 112 function as anodes, the conductive layer 112c has a high work function. For example, the conductive layer 112c has a higher work function than the conductive layer 112b. This can reduce the driving voltage of the light-emitting element 130. For example, the conductive layer 112c can be made of the same material as that of the conductive layer 112a. For example, the conductive layer 112a and the conductive layer 112c can be made of the same material. For example, when indium tin oxide is used for the conductive layer 112a, indium tin oxide can also be used for the conductive layer 112c.

[0201] Note that when the conductive layers 111 and 112 function as cathodes, the conductive layer 112c has a smaller work function than the conductive layer 112b, for example. This allows the driving voltage of the light-emitting element 130 to be lower.

[0202] The conductive layer 112c is preferably a layer having high transmittance to visible light. For example, the transmittance of the conductive layer 112c to visible light is preferably higher than that of the conductive layer 111 and the conductive layer 112b to visible light. For example, the transmittance of the conductive layer 112c to visible light can be 60% to 100%, preferably 70% to 100%, and more preferably 80% to 100%. As a result, the amount of light emitted from the EL layer 113 that is absorbed by the conductive layer 112c can be reduced. As described above, the conductive layer 112b below the conductive layer 112c can be a layer having high reflectance to visible light. Therefore, the display device 100 can have high light extraction efficiency.

[0203] 4A is a layer having high reflectivity for light emitted by the EL layer 113, and the conductive layer 112c is a layer having high transmittance for light emitted by the EL layer 113. For example, when the EL layer 113 emits infrared light, the conductive layer 112b is a layer having high reflectivity for infrared light, and the conductive layer 112c is a layer having high transmittance for infrared light. For example, when the EL layer 113 emits infrared light, visible light can be read as infrared light in the above description of the conductive layers 112b and 112c shown in FIG. 4A.

[0204] As a result, the display device 100 can be a display device with high reliability and high light extraction efficiency. Furthermore, the display device 100 can be a display device having light-emitting elements with high light-emitting efficiency.

[0205] 4B and 4C are cross-sectional views showing examples of the conductive layer 111 and the conductive layer 112 that are different from those shown in FIG. 4A. In the example shown in FIG. 4B, the conductive layer 111 has a two-layer structure including a conductive layer 111a and a conductive layer 111b on the conductive layer 111a. In the example shown in FIG. 4C, the conductive layer 111 has a three-layer structure including a conductive layer 111a, a conductive layer 111b on the conductive layer 111a, and a conductive layer 111c on the conductive layer 111b.

[0206] The conductive layer 111a and the conductive layer 111c can be made of the same material as the conductive layer 111 shown in FIG. 4A , such as titanium or an alloy containing titanium. The conductive layer 111b can be made of, for example, a layer having a higher reflectivity to visible light than the conductive layer 111a. The conductive layer 111b can also be made of, for example, a layer having a higher etching processability than the conductive layer 112b. As described above, the thickness of the conductive layer 112b, which can be made of, for example, silver or an alloy containing silver, can be reduced while increasing the reflectivity of the pixel electrode to visible light. Therefore, the display device 100 has high light extraction efficiency and can be easily manufactured. The conductive layer 111b can be made of, for example, aluminum or an aluminum alloy.

[0207] Next, the structure of the insulating layer 127 and its vicinity will be described using Figures 5A and 5B. Figure 5A is an enlarged cross-sectional view of the insulating layer 127 between the EL layer 113R and the EL layer 113G and its surrounding area. The following description will be given using the insulating layer 127 between the EL layer 113R and the EL layer 113G as an example, but the same applies to the insulating layer 127 between the EL layer 113G and the EL layer 113B, and the insulating layer 127 between the EL layer 113B and the EL layer 113R. Figure 5B is an enlarged view of the end of the insulating layer 127 on the EL layer 113G shown in Figure 5A and its vicinity. The following description will sometimes be given using the end of the insulating layer 127 on the EL layer 113G as an example, but the same applies to the end of the insulating layer 127 on the EL layer 113R and the end of the insulating layer 127 on the EL layer 113B.

[0208] As shown in FIG. 5A , an EL layer 113R is provided covering the conductive layer 112R, and an EL layer 113G is provided covering the conductive layer 112G. A mask layer 118R is provided in contact with a portion of the upper surface of the EL layer 113R, and a mask layer 118G is provided in contact with a portion of the upper surface of the EL layer 113G. An insulating layer 125 is provided so as to have regions in contact with the upper and side surfaces of the mask layer 118R, the side surfaces of the EL layer 113R, the upper surface of the insulating layer 105, the upper and side surfaces of the mask layer 118G, and the side surfaces of the EL layer 113G. An insulating layer 127 is provided in contact with the upper surface of the insulating layer 125. Furthermore, the insulating layer 127 overlaps with a portion of the upper surface and side surfaces of the EL layer 113R and a portion of the upper surface and side surfaces of the EL layer 113G via the insulating layer 125, and is in contact with at least a portion of the upper surface and side surfaces of the insulating layer 125. A common layer 114 is provided to cover the EL layer 113R, the mask layer 118R, the EL layer 113G, the mask layer 118G, the insulating layer 125, and the insulating layer 127, and a common electrode 115 is provided on the common layer 114.

[0209] 5A , the thickness of the insulating layer 105 in the region that does not overlap with the EL layer 113 may be thinner than the thickness of the insulating layer 105 in the region that overlaps with the EL layer 113. In other words, the insulating layer 105 may have a recess in the region that does not overlap with the EL layer 113. The recess is formed, for example, due to the process of forming the EL layer 113.

[0210] Furthermore, the insulating layer 127 is formed in a region between two island-shaped EL layers 113 (for example, in FIG. 5A , the region between the EL layer 113R and the EL layer 113G). At this time, at least a portion of the insulating layer 127 is disposed at a position sandwiched between a side edge of one EL layer 113 (for example, in FIG. 5A , the EL layer 113R) and a side edge of the other EL layer 113 (for example, in FIG. 5A , the EL layer 113G). By providing such an insulating layer 127, it is possible to prevent the formation of divided portions and locally thin portions in the common layer 114 and the common electrode 115 formed on the island-shaped EL layer 113 and the insulating layer 127.

[0211] 5B , the insulating layer 127 preferably has a tapered shape at an end portion with a taper angle θ1 in a cross-sectional view of the display device 100. The taper angle θ1 is the angle between the side surface of the insulating layer 127 and the substrate surface. However, the taper angle θ1 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 EL layer 113G or the upper surface of the flat portion of the conductive layer 112G.

[0212] The taper angle θ1 of the insulating layer 127 is less than 90°, preferably 60° or less, more preferably 45° or less, and even more preferably 20° or less. By forming the end of the insulating layer 127 in such a forward tapered shape, the common layer 114 and the common electrode 115 provided on the insulating layer 127 can be formed with good coverage, and the occurrence of discontinuities, local thinning, etc. can be suppressed. This improves the in-plane uniformity of the common layer 114 and the common electrode 115, and improves the display quality of the display device.

[0213] 5A , in a cross-sectional view of the display device 100, 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 portions at the edges. 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.

[0214] 5B , the end of the insulating layer 127 is preferably positioned outside the end of the insulating layer 125. This makes it possible to suitably reduce the unevenness of the surface on which the common layer 114 and the common electrode 115 are formed, and to improve the coverage of the common layer 114 and the common electrode 115.

[0215] 5B , the insulating layer 125 preferably has a tapered shape at an end portion with a taper angle θ2 in a cross-sectional view of the display device 100. The taper angle θ2 is the angle between the side surface of the insulating layer 125 and the substrate surface. However, the taper angle θ2 is not limited to the substrate surface, and may be the angle between the side surface of the insulating layer 125 and the upper surface of the flat portion of the EL layer 113G or the upper surface of the flat portion of the conductive layer 112G.

[0216] The taper angle θ2 of the insulating layer 125 is less than 90°, preferably 60° or less, more preferably 45° or less, and even more preferably 20° or less.

[0217] 5B , the mask layer 118G preferably has a tapered shape at its end with a taper angle θ3 in a cross-sectional view of the display device 100. The taper angle θ3 is the angle between the side surface of the mask layer 118G 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 118G and the upper surface of the flat portion of the EL layer 113G or the upper surface of the flat portion of the conductive layer 112G.

[0218] The taper angle θ3 of the mask layer 118G is less than 90°, preferably equal to or less than 60°, more preferably equal to or less than 45°, and even more preferably equal to or less than 20°. By forming the mask layer 118G in such a forward tapered shape, the common layer 114 and the common electrode 115 provided on the mask layer 118G can be formed with good coverage.

[0219] The ends of the mask layers 118R and 118G are preferably located outside the ends of the insulating layer 125. This reduces the unevenness of the surfaces on which the common layer 114 and the common electrode 115 are formed, and improves the coverage of the common layer 114 and the common electrode 115.

[0220] As will be described in detail later, if the insulating layer 125 and the mask layer 118 are etched at the same time, side etching may cause the insulating layer 125 and the mask layer 118 below the edges of the insulating layer 127 to disappear, forming cavities. These cavities may cause unevenness on the surfaces on which the common layer 114 and the common electrode 115 are formed, making the common layer 114 and the common electrode 115 more likely to break apart. Therefore, by performing the etching process in two stages and performing a heat treatment between the two etchings, even if cavities are formed in the first etching process, the heat treatment deforms the insulating layer 127, thereby filling the cavities. Furthermore, because the second etching process involves etching a thin film, the amount of side etching is reduced, making it less likely that cavities will form. Even if cavities do form, they can be kept extremely small. This prevents unevenness from forming on the surfaces on which the common layer 114 and the common electrode 115 are formed, and also prevents the common layer 114 and the common electrode 115 from breaking apart. Since the etching process is performed twice in this manner, the taper angles θ2 and θ3 may be different from each other. Alternatively, the taper angles θ2 and θ3 may be the same. Alternatively, the taper angles θ2 and θ3 may be smaller than the taper angle θ1.

[0221] The insulating layer 127 may cover at least a portion of the side surface of the mask layer 118R and at least a portion of the side surface of the mask layer 118G. For example, FIG. 5B shows an example in which the insulating layer 127 contacts and covers the inclined surface located at the end of the mask layer 118G formed by the first etching process, while the inclined surface located at the end of the mask layer 118G formed by the second etching process is exposed. These two inclined surfaces may be distinguishable because they have different taper angles. Alternatively, there may be little difference in the taper angles of the side surfaces formed by the two etching processes, making them indistinguishable.

[0222] 6A and 6B are modified versions of the configuration shown in FIGS. 5A and 5B , showing an example in which the insulating layer 127 covers the entire side surfaces of the mask layer 118R and the entire side surfaces of the mask layer 118G. Specifically, in FIG. 6B , the insulating layer 127 contacts and covers both of the two inclined surfaces. This is preferable because it further reduces the unevenness of the surfaces on which the common layer 114 and the common electrode 115 are formed. FIG. 6B shows an example in which the end of the insulating layer 127 is located outside the end of the mask layer 118G. As shown in FIG. 6B , the end of the insulating layer 127 may be located inside the end of the mask layer 118G, or may be aligned or approximately aligned with the end of the mask layer 118G. Also, as shown in FIG. 6B , the insulating layer 127 may contact the EL layer 113G.

[0223] 7A and 8A show modified examples of the configuration shown in Fig. 5A, and Fig. 7B and 8B show modified examples of the configuration shown in Fig. 5B. Fig. 7A, Fig. 7B, Fig. 8A, and Fig. 8B show examples in which the insulating layer 127 has a concave curved shape (also referred to as a constricted portion, a recess, a dent, or a depression, etc.) on the side surface. Depending on the material and forming conditions (heating temperature, heating time, heating atmosphere, etc.) of the insulating layer 127, a concave curved shape may be formed on the side surface of the insulating layer 127.

[0224] 7A and 7B show an example in which the insulating layer 127 covers a part of the side surface of the mask layer 118G and the remaining part of the side surface of the mask layer 118G is exposed. Figures 8A and 8B show an example in which the insulating layer 127 contacts and covers the entire side surface of the mask layer 118G.

[0225] In the configurations shown in FIGS. 6B, 7B, and 8B, it is also preferable that the taper angles θ1 to θ3 are each within the above ranges.

[0226] 5A, 6A, 7A, and 8A, it is preferable that one end of the insulating layer 127 overlaps the top surface of the conductive layer 111R and the other end of the insulating layer 127 overlaps the top surface of the conductive layer 111G. This structure allows the end of the insulating layer 127 to be formed on the generally flat regions of the EL layer 113R and the EL layer 113G. This makes it relatively easy to form the tapered shapes of the insulating layer 127, the insulating layer 125, and the mask layer 118. Furthermore, peeling of the conductive layer 111R, the conductive layer 111G, the conductive layer 112R, the conductive layer 112G, the EL layer 113R, and the EL layer 113G can be suppressed. On the other hand, the smaller the overlapping portion between the top surface of the pixel electrode and the insulating layer 127, the wider the light-emitting region of the light-emitting element, which increases the aperture ratio, which is preferable.

[0227] As described above, in each of the configurations shown in FIGS. 5 to 8 , the insulating layer 127, the insulating layer 125, the mask layer 118R, and the mask layer 118G are provided, thereby enabling the common layer 114 and the common electrode 115 to be formed with high coverage from the generally flat region of the EL layer 113R to the generally flat region of the EL layer 113G. This also prevents the formation of disconnected portions and locally thin portions in the common layer 114 and the common electrode 115. This prevents poor connections between the light-emitting elements 130 in the common layer 114 and the common electrode 115 due to disconnected portions and increases in electrical resistance due to locally thin portions. This allows the display device 100 to have high display quality.

[0228] 9A and 9B are modified examples of the configuration shown in FIG. 5A . FIG. 9A shows an example in which the side of insulating layer 105, specifically the side of insulating layer 105 at the boundary between the region overlapping with conductive layer 111 and the region not overlapping with it (the portion surrounded by a dashed line in FIG. 9A ), is vertical. FIG. 9B shows an example in which the top surface of insulating layer 127 has a recessed shape in the center and its vicinity in a cross-sectional view, i.e., a shape with a concave curved surface. Furthermore, by configuring insulating layer 127 to have a concave curved surface in the center as shown in FIG. 9B , stress in insulating layer 127 can be alleviated. More specifically, by configuring the insulating layer 127 to have a concave curved surface in the center, local stress occurring at the ends of the insulating layer 127 can be alleviated, and one or more of film peeling between the EL layer 113R and the EL layer 113G and the mask layer 118R and the mask layer 118G, film peeling between the mask layer 118R and the mask layer 118G and the insulating layer 125, and film peeling between the insulating layer 125 and the insulating layer 127 can be suppressed.

[0229] To achieve a configuration in which the insulating layer 127 has a concave curved surface in the center as shown in FIG. 9B , exposure can be performed using a multi-tone mask, typically a half-tone mask or a gray-tone mask. A multi-tone mask is a mask that can perform three exposure levels: exposed, intermediately exposed, and unexposed. This mask allows the transmitted light to have multiple intensities. Using a single photomask (a single exposure and development process), it is possible to form the insulating layer 127 with regions of multiple thicknesses (typically two types). Alternatively, to achieve a configuration in which the insulating layer 127 has a concave curved surface in the center, the line width of the mask located at the concave curved surface can be made smaller than the line width of the exposed portion, thereby forming the insulating layer 127 with regions of multiple thicknesses.

[0230] The method for forming the insulating layer 127 having a concave curved surface in the center is not limited to the above. For example, two photomasks may be used to separately form an exposed portion and an intermediately exposed portion. Alternatively, the viscosity of the resin material used for the insulating layer 127 may be adjusted. Specifically, the viscosity of the material used for the insulating layer 127 may be adjusted to 10 cP or less, preferably 1 cP or more and 5 cP or less.

[0231] Although not shown in Fig. 9B , the concave curved surface in the central portion of the insulating layer 127 does not necessarily have to be continuous, and may be interrupted between adjacent light-emitting elements. In this case, a portion of the insulating layer 127 disappears in the central portion of the insulating layer 127 shown in Fig. 9B , exposing the surface of the insulating layer 125. In this case, the shape of the insulating layer 127 may be such that the common layer 114 and the common electrode 115 can cover the insulating layer 127.

[0232] [Configuration Example 2] Figure 10 is a modified example of the configuration shown in Figure 2A, showing an example in which the edge of the mask layer 118R is aligned or approximately aligned with the edge of the conductive layer 112R as well as the edge of the EL layer 113R. That is, Figure 10 shows an example in which the edge of the conductive layer 112R is aligned or approximately aligned with the edge of the EL layer 113R. Similarly, in the example shown in Figure 10, the edge of the mask layer 118G is aligned or approximately aligned with the edge of the conductive layer 112G as well as the edge of the EL layer 113G, and the edge of the mask layer 118B is aligned or approximately aligned with the edge of the conductive layer 112B as well as the edge of the EL layer 113B. That is, in the example shown in Figure 10, the edge of the conductive layer 112G is aligned or approximately aligned with the edge of the EL layer 113G, and the edge of the conductive layer 112B is aligned or approximately aligned with the edge of the EL layer 113B. Furthermore, in the example shown in Figure 10, the insulating layer 125 has areas that contact the side surfaces of the EL layer 113R, the side surfaces of the EL layer 113G, and the side surfaces of the EL layer 113B, as well as the side surfaces of the conductive layer 112R, the side surfaces of the conductive layer 112G, and the side surfaces of the conductive layer 112B.

[0233] Fig. 11A is an enlarged cross-sectional view of the insulating layer 127 between the EL layer 113R and the EL layer 113G and the surrounding area in the configuration shown in Fig. 10, which is a modification of the configuration shown in Fig. 5A. In the example shown in Fig. 11A, the EL layer 113R is provided on the conductive layer 112R, and the EL layer 113G is provided on the conductive layer 112G.

[0234] 11B, 12A, 12B, 13A, and 13B are modified examples of the configurations shown in FIGS. 6A, 7A, 8A, 9A, and 9B, respectively, and are examples in which the configuration shown in FIG. 10 is applied.

[0235] 14 is a modified example of the configuration shown in FIG. 2A , showing an example in which a tandem structure (a structure having a plurality of light-emitting units) is applied to the light-emitting element 130. The light-emitting unit has at least one light-emitting layer. It is preferable to provide a charge generation layer between each light-emitting unit.

[0236] 14 shows a configuration example in which a two-stage tandem structure in which two light-emitting units are stacked is applied to the light-emitting element 130. In Fig. 14, the dashed line in the EL layer 113 indicates the charge generation layer. Note that in the subsequent drawings, the charge generation layer of the EL layer 113 may also be indicated by the dashed line.

[0237] In the example shown in FIG. 14 , the EL layer 113 includes a first light-emitting unit below the charge generation layer and a second light-emitting unit above the charge generation layer. Applying a tandem structure to the light-emitting element 130 can increase the current efficiency associated with light emission, thereby improving the light-emitting efficiency of the light-emitting element 130. Alternatively, the current density flowing through the light-emitting element 130 can be reduced at the same light-emitting luminance, thereby reducing the power consumption of the display device 100 including the light-emitting element 130. Furthermore, applying a tandem structure to the light-emitting element 130 can improve the reliability of the light-emitting element 130. Note that a three- or more-stage tandem structure may be applied to the light-emitting element 130. For example, when a three-stage tandem structure is applied to the light-emitting element 130, the EL layer 113 may be configured such that, from bottom to top, a first light-emitting unit, a first charge generation layer, a second light-emitting unit, a second charge generation layer, and a third light-emitting unit are stacked.

[0238] As described above, the EL layer 113R, the EL layer 113G, and the EL layer 113B each have at least a light-emitting layer. For example, the first light-emitting unit and the second light-emitting unit in the EL layer 113R each have a light-emitting layer that emits red light. The first light-emitting unit and the second light-emitting unit in the EL layer 113G each have a light-emitting layer that emits green light. Furthermore, the first light-emitting unit and the second light-emitting unit in the EL layer 113B each have a light-emitting layer that emits blue light.

[0239] Each of the light-emitting units in the EL layer 113R, the EL layer 113G, and the EL layer 113B may 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.

[0240] 14 , for example, when the pixel electrode of the light-emitting element 130 functions as an anode and the common electrode 115 functions as a cathode, the first light-emitting unit included in the EL layer 113R, the EL layer 113G, and the EL layer 113B may have a hole injection layer, a hole transport layer, a light-emitting layer, and an electron transport layer in this order. That is, the first light-emitting unit included in the EL layer 113 may have a configuration in which, for example, from bottom to top, a first functional layer including a hole injection layer and a hole transport layer, a light-emitting layer, and a second functional layer including an electron transport layer are stacked. Furthermore, the second light-emitting unit included in the EL layer 113R, the EL layer 113G, and the EL layer 113B may have a hole transport layer, a light-emitting layer, and an electron transport layer in this order. In other words, the second light-emitting unit of the EL layer 113 can be configured, for example, by stacking, from the bottom, a third functional layer having a hole transport layer, a light-emitting layer, and a fourth functional layer having an electron transport layer.

[0241] Here, the first light-emitting unit and the second light-emitting unit may have an electron blocking layer between the hole transport layer and the light-emitting layer. Alternatively, a hole blocking layer may be provided between the electron transport layer and the light-emitting layer. Alternatively, the second light-emitting unit may have an electron injection layer on the electron transport layer. The first functional layer may have either a hole injection layer or a hole transport layer, but not the other.

[0242] Furthermore, for example, when the pixel electrode of the light-emitting element 130 functions as a cathode and the common electrode 115 functions as an anode, the first light-emitting unit included in the EL layer 113R, the EL layer 113G, and the EL layer 113B may have an electron injection layer, an electron transport layer, a light-emitting layer, and a hole transport layer in this order. That is, the first light-emitting unit included in the EL layer 113 may have a configuration in which, for example, from the bottom, a first functional layer including an electron injection layer and an electron transport layer, a light-emitting layer, and a second functional layer including a hole transport layer are stacked. Furthermore, the second light-emitting unit included in the EL layer 113R, the EL layer 113G, and the EL layer 113B may have an electron transport layer, a light-emitting layer, and a hole transport layer in this order. In other words, the second light-emitting unit of the EL layer 113 can be configured, for example, by stacking, from the bottom, a third functional layer having an electron transport layer, a light-emitting layer, and a fourth functional layer having a hole transport layer.

[0243] Here, the first light-emitting unit and the second light-emitting unit may have a hole-blocking layer between the electron-transporting layer and the light-emitting layer. Alternatively, an electron-blocking layer may be provided between the hole-transporting layer and the light-emitting layer. Alternatively, the second light-emitting unit may have a hole-injection layer on the hole-transporting layer. The first functional layer may have either an electron-injection layer or an electron-transporting layer, but not the other.

[0244] Regardless of whether the pixel electrode of the light-emitting element 130 functions as an anode or a cathode, the first light-emitting unit does not necessarily have to have the second functional layer. Furthermore, the second light-emitting unit does not necessarily have to have at least one of the third functional layer and the fourth functional layer.

[0245] The second light-emitting unit preferably has an emitting layer and a carrier transport layer on the emitting layer. The second light-emitting unit preferably has an emitting layer and a carrier block layer on the emitting layer. The second light-emitting unit preferably has an emitting layer, a carrier block layer on the emitting layer, and a carrier transport layer on the carrier block layer. The surface of the second light-emitting unit is exposed during the manufacturing process of the display device. Therefore, by providing one or both of the carrier transport layer and the carrier block layer on the emitting layer, the emitting layer is prevented from being exposed on the outermost surface, thereby reducing damage to the emitting layer. This improves the reliability of the light-emitting element. When three or more emitting units are included, the uppermost emitting unit preferably has an emitting layer and one or both of the carrier transport layer and the carrier block layer on the emitting layer.

[0246] As described above, the light-emitting element 130 can have a tandem structure. For a detailed configuration of the light-emitting element 130 having a tandem structure, refer to embodiment 2. Furthermore, regardless of whether the light-emitting element 130 has a single structure or a tandem structure, refer to embodiment 5 for the configuration and materials of the light-emitting element 130.

[0247] FIG. 15A is an enlarged cross-sectional view of the insulating layer 127 between the EL layer 113R and the EL layer 113G and the surrounding area in the configuration shown in FIG. 14, and is a modification of the configuration shown in FIG. 5A.

[0248] 15A , the EL layer 113R includes, for example, a light-emitting unit 113R1, a charge generation layer 113R2 on the light-emitting unit 113R1, and a light-emitting unit 113R3 on the charge generation layer 113R2. The EL layer 113G includes, for example, a light-emitting unit 113G1, a charge generation layer 113G2 on the light-emitting unit 113G1, and a light-emitting unit 113G3 on the charge generation layer 113G2. The layer indicated by the dashed line in the EL layer 113R shown in FIG. 14 corresponds to the charge generation layer 113R2, and the layer indicated by the dashed line in the EL layer 113G corresponds to the charge generation layer 113G2.

[0249] When a two-stage tandem structure is applied to the light-emitting element 130R and the light-emitting element 130G, the light-emitting unit 113R1 and the light-emitting unit 113G1 can be the first light-emitting unit described in Figure 14, and the light-emitting unit 113R3 and the light-emitting unit 113G3 can be the second light-emitting unit described in Figure 14.

[0250] Figures 15B, 16A, 16B, and 17A are modifications of the configurations shown in Figures 6A, 7A, 8A, and 9B, respectively, and are examples in which the configuration shown in Figure 14 is applied. Figure 17B is a modification of the configuration shown in Figure 15A, and shows an example in which the upper surface of insulating layer 127 has a flat portion in a cross-sectional view.

[0251] 18A is a cross-sectional view showing a configuration example of a region 141 and a connection portion 140. In the region 141, a conductive layer 109 is provided over an insulating layer 101, and an insulating layer 103 is provided over the insulating layer 101 and the conductive layer 109. The conductive layer 109 can be formed in the same process as the conductive layer 102 shown in FIG. 2A and can have the same material as the conductive layer 102.

[0252] In the region 141, the EL layer 113R on the insulating layer 105, the mask layer 118R on the insulating layer 105 and on the EL layer 113R, the insulating layer 125 on the mask layer 118R, the insulating layer 127 on the insulating layer 125, the common layer 114 on the insulating layer 127, the common electrode 115 on the common layer 114, the protective layer 131 on the common electrode 115, the resin layer 122 on the protective layer 131, and the substrate 120 on the resin layer 122 are provided. In the region 141, the mask layer 118R is provided so as to cover, for example, an end portion of the EL layer 113R. Note that, for example, depending on the manufacturing process of the display device 100, the EL layer 113G or the EL layer 113B may be provided in the region 141 instead of the EL layer 113R. Furthermore, the mask layer 118G or the mask layer 118B may be provided in the region 141 instead of the mask layer 118R.

[0253] The EL layer 113R provided in the region 141 is not electrically connected to the common electrode 115. Therefore, the EL layer 113R provided in the region 141 can be configured so that no voltage is applied thereto, and therefore the EL layer 113R provided in the region 141 can be configured so that it does not emit light.

[0254] In a display device having a configuration in which the EL layer 113R and the mask layer 118R are provided in the region 141, as will be described in detail later, parts of the insulating layers 105, 104, and 103 are removed by etching or the like during the manufacturing process of the display device, and the conductive layer 109 can be prevented from being exposed. This prevents the conductive layer 109 from unintentionally contacting other electrodes or layers. For example, it prevents a short circuit between the conductive layer 109 and the common electrode 115. As described above, the display device 100 can be a highly reliable display device. Furthermore, the display device 100 can be manufactured by a method with a high yield.

[0255] The connection portion 140 includes a conductive layer 111C on the insulating layer 105, a conductive layer 112C covering the top and side surfaces of the conductive layer 111C, a common layer 114 on the conductive layer 112C, a common electrode 115 on the common layer 114, a protective layer 131 on the common electrode 115, a resin layer 122 on the protective layer 131, and a substrate 120 on the resin layer 122. A mask layer 118R is provided to cover an end of the conductive layer 112C, and an insulating layer 125, an insulating layer 127, the common layer 114, the common electrode 115, and the protective layer 131 are stacked in this order on the mask layer 118R. When a mask layer 118G or a mask layer 118B is provided in the region 141 instead of the mask layer 118R, the connection portion 140 also includes a mask layer 118G or a mask layer 118B in place of the mask layer 118R.

[0256] At the connection portion 140, the conductive layer 111C and the conductive layer 112C are electrically connected to the common electrode 115. The conductive layer 111C and the conductive layer 112C are electrically connected to, for example, an FPC (Flexible Printed Circuit) (not shown). As described above, by supplying a power supply potential to, for example, the FPC, the power supply potential can be supplied to the common electrode 115 via the conductive layer 111C and the conductive layer 112C.

[0257] Here, if the electrical resistance of the common layer 114 in the thickness direction is negligibly small, even when the common layer 114 is provided between the conductive layer 112C and the common electrode 115, electrical continuity between the conductive layer 111C and the conductive layer 112C and the common electrode 115 can be ensured. By providing the common layer 114 not only in the pixel portion 107 but also in the region 141 and the connection portion 140, the common layer 114 can be formed without using a metal mask, including 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). Thus, the manufacturing process of the display device 100 can be simplified.

[0258] FIG. 18B is a modified example of the configuration shown in FIG. 18A , illustrating an example in which the common layer 114 is not provided in the connection portion 140. In the example shown in FIG. 18B , the conductive layer 112C and the common electrode 115 can be configured to be in contact with each other. This reduces the electrical resistance between the conductive layer 112C and the common electrode 115. Note that FIG. 18B illustrates a configuration in which the common layer 114 is provided in the region overlapping with the EL layer 113R in the region 141 and is not provided in the region not overlapping with the EL layer 113R. However, this is not limiting. For example, the common layer 114 may not be provided in the region overlapping with the EL layer 113R in the region 141, or the common layer 114 may be provided in the region not overlapping with the EL layer 113R.

[0259] 18C and 18D are modifications of the configurations shown in Figures 18A and 18B, respectively, and show an example in which conductive layer 112C is provided not only in connection portion 140 but also in region 141. In the examples shown in Figures 18C and 18D, in region 141, conductive layer 112C is provided on insulating layer 105, EL layer 113R is provided on conductive layer 112C, and mask layer 118R is provided on conductive layer 112C and EL layer 113R. Furthermore, in connection portion 140, mask layer 118R is provided on conductive layer 112C.

[0260] 18E and 18F are modifications of the configurations shown in FIGS. 18A and 18B, respectively, and show an example in which a tandem structure is applied to the EL layer 113R.

[0261] [Configuration Example 4] FIG. 19A shows a modification of the configuration shown in FIG. 2A, in which the subpixel 110R has a colored layer 132R, the subpixel 110G has a colored layer 132G, and the subpixel 110B has a colored layer 132B.

[0262] 19A, the colored layer 132R, the colored layer 132G, and the colored layer 132B can be provided on the protective layer 131. In this case, the protective layer 131 is preferably planarized, but does not have to be planarized.

[0263] In the example shown in Figure 19A, the light-emitting element 130 of the sub-pixel 110R, the light-emitting element 130 of the sub-pixel 110G, and the light-emitting element 130 of the sub-pixel 110B can all emit light of the same color, for example, white light. Even in this case, for example, the colored layer 132R transmits red light, the colored layer 132G transmits green light, and the colored layer 132B transmits blue light, thereby allowing the display device 100 having the configuration shown in Figure 19A to perform full-color display. Note that the colored layer 132R, the colored layer 132G, or the colored layer 132B may transmit light of cyan, magenta, yellow, white, infrared, or the like. Furthermore, the light-emitting element 130 may emit, for example, infrared light.

[0264] 19A does not require separate EL layers 113 for each color, which simplifies the manufacturing process of the display device 100. This reduces the manufacturing cost of the display device 100, making the display device 100 an inexpensive display device.

[0265] Adjacent colored layers 132 have overlapping regions on the insulating layer 127. For example, in the cross section shown in FIG. 19A , one end of the colored layer 132G overlaps with the colored layer 132R, and the other end of the colored layer 132G overlaps with the colored layer 132B. This makes it possible to suppress leakage of light emitted by the light-emitting element 130 into the adjacent sub-pixel 110. Therefore, for example, it is possible to suppress light emitted by the light-emitting element 130 provided in the sub-pixel 110G from entering the colored layer 132R and the colored layer 132B. This allows the display device 100 to have high display quality.

[0266] Fig. 19B is an enlarged cross-sectional view of the insulating layer 127 between the two EL layers 113 shown in Fig. 19A and the surrounding area. Note that Fig. 19B shows conductive layers 112R and 112G as the conductive layer 112. The shapes of the mask layer 118, insulating layer 125, insulating layer 127, etc. shown in Fig. 19B are the same as those in Fig. 5A.

[0267] As shown in FIGS. 19A and 19B , the conductive layers 112R, 112G, and 112B can have different thicknesses. For example, it is preferable to set the thicknesses corresponding to the optical path length that enhances the color of light transmitted through the colored layer 132. For example, if the colored layer 132R transmits red light, it is preferable to set the thickness of the conductive layer 112R so as to enhance the red light; if the colored layer 132G transmits green light, it is preferable to set the thickness of the conductive layer 112G so as to enhance the green light; and if the colored layer 132B transmits blue light, it is preferable to set the thickness of the conductive layer 112B so as to enhance the blue light. This realizes a microcavity structure and improves the color purity of the light emitted from the subpixel 110. It should be noted that, for example, even in the configuration shown in FIG. 2A , the conductive layers 112R, 112G, and 112B may have different thicknesses. In this case, even if the EL layers 113R, 113G, and 113B all have the same film thickness, a microcavity structure can be realized.

[0268] While FIG. 19B illustrates the light-emitting element 130 having a single structure, it may also have a tandem structure. FIG. 20A illustrates an example in which the EL layer 113 includes a light-emitting unit 113a1, a charge generation layer 113b1 on the light-emitting unit 113a1, and a light-emitting unit 113c1 on the charge generation layer 113b1. The light-emitting element 130 having the EL layer 113 shown in FIG. 20A has a two-tier tandem structure. Applying a tandem structure to the light-emitting element 130 can increase the current efficiency associated with light emission, thereby improving the luminous efficiency of the light-emitting element 130. Alternatively, the current density flowing through the light-emitting element 130 can be reduced for the same luminance, thereby reducing the power consumption of the display device 100 including the light-emitting element 130. Furthermore, applying a tandem structure to the light-emitting element 130 can improve the reliability of the light-emitting element 130.

[0269] The light-emitting unit 113a1 and the light-emitting unit 113c1 each have at least one light-emitting layer. The color of light emitted by the light-emitting unit 113a1 can be different from the color of light emitted by the light-emitting unit 113c1.

[0270] In this specification and the like, light emitted from a light-emitting layer included in a light-emitting unit is referred to as light emitted by the light-emitting unit.

[0271] The color of light emitted by the light-emitting layer of the light-emitting unit 113a1 and the color of light emitted by the light-emitting layer of the light-emitting unit 113c1 can be, for example, complementary colors. For example, one of the light-emitting units 113a1 and 113c1 can emit blue light, and the other of the light-emitting units 113a1 and 113c1 can emit yellow light. For example, one of the light-emitting units 113a1 and 113c1 can emit blue light, and the other of the light-emitting units 113a1 and 113c1 can emit red and green light. For example, when the pixel electrode of the light-emitting element 130 functions as an anode and the common electrode 115 functions as a cathode, the light-emitting unit 113a1 can emit blue light. As a result, the light-emitting element 130 can emit white light.

[0272] Furthermore, the light-emitting unit 113a1 and the light-emitting unit 113c1 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 in addition to the light-emitting layer. That is, the light-emitting unit 113a1 and the light-emitting unit 113c1 may have a functional layer. Light-emitting units other than the light-emitting unit 113a1 and the light-emitting unit 113c1 may also have a similar configuration.

[0273] For example, when the pixel electrode of the light-emitting element 130 functions as an anode and the common electrode 115 functions as a cathode, the light-emitting unit 113a1 can be configured, for example, by stacking, from bottom to top, a first functional layer having a hole injection layer and a hole transport layer, a light-emitting layer, and a second functional layer having an electron transport layer. Alternatively, the light-emitting unit 113c1 may have, in this order, a hole transport layer, a light-emitting layer, and an electron transport layer. That is, the light-emitting unit 113c1 can be configured, for example, by stacking, from bottom to top, a third functional layer having a hole transport layer, a light-emitting layer, and a fourth functional layer having an electron transport layer.

[0274] Here, the light-emitting unit 113a1 and the light-emitting unit 113c1 may have an electron blocking layer between the hole transport layer and the light-emitting layer. Alternatively, a hole blocking layer may be provided between the electron transport layer and the light-emitting layer. Furthermore, the light-emitting unit 113c1 may have an electron injection layer between the electron transport layer and the common electrode 115. The first functional layer may have either a hole injection layer or a hole transport layer, but not the other.

[0275] Furthermore, for example, when the pixel electrode of the light-emitting element 130 functions as a cathode and the common electrode 115 functions as an anode, the light-emitting unit 113a1 can be configured, for example, by stacking, from bottom to top, a first functional layer having an electron injection layer and an electron transport layer, a light-emitting layer, and a second functional layer having a hole transport layer. The light-emitting unit 113c1 may also have, in this order, an electron transport layer, a light-emitting layer, and a hole transport layer. That is, the light-emitting unit 113c1 can be configured, for example, by stacking, from bottom to top, a third functional layer having an electron transport layer, a light-emitting layer, and a fourth functional layer having a hole transport layer.

[0276] Here, the light-emitting unit 113a1 and the light-emitting unit 113c1 may have a hole-blocking layer between the electron-transporting layer and the light-emitting layer. Alternatively, the light-emitting unit 113c1 may have an electron-blocking layer between the hole-transporting layer and the light-emitting layer. Alternatively, the light-emitting unit 113c1 may have a hole-injection layer between the hole-transporting layer and the common electrode 115. The first functional layer may have either an electron-injection layer or an electron-transporting layer, but not the other.

[0277] Regardless of whether the pixel electrode of the light-emitting element 130 functions as an anode or a cathode, the light-emitting unit 113a1 does not need to have the second functional layer. Furthermore, the light-emitting unit 113c1 does not need to have at least one of the third functional layer and the fourth functional layer.

[0278] The charge generation layer 113b1 has at least a charge generation region, and when a voltage is applied between the pixel electrode of the light-emitting element 130 and the common electrode 115, the charge generation layer 113b1 has a function of injecting electrons into one of the light-emitting units 113a1 and 113c1 and injecting holes into the other of the light-emitting units 113a1 and 113c1.

[0279] FIG. 20B illustrates an example in which the EL layer 113 includes a light-emitting unit 113a2, a charge generation layer 113b2 on the light-emitting unit 113a2, a light-emitting unit 113c2 on the charge generation layer 113b2, a charge generation layer 113d on the light-emitting unit 113c2, and a light-emitting unit 113e on the charge generation layer 113d. The light-emitting element 130 having the EL layer 113 shown in FIG. 20B has a three-stage tandem structure. Increasing the number of stages in the tandem structure can favorably increase the current efficiency related to the light emission of the light-emitting element 130, thereby favorably improving the light-emitting efficiency of the light-emitting element 130. Alternatively, the current density flowing through the light-emitting element 130 can be favorably reduced for the same light emission luminance, thereby favorably reducing the power consumption of the display device 100 including the light-emitting element 130. Furthermore, the reliability of the light-emitting element 130 can be favorably improved. The light-emitting element 130 may also have a four-stage or more tandem structure.

[0280] The light-emitting units 113a2, 113c2, and 113e each have at least one light-emitting layer. The color of light emitted by at least one of the light-emitting units 113a2, 113c2, and 113e can be different from the color of light emitted by the other light-emitting units. For example, the color of light emitted by at least one of the light-emitting units 113a2, 113c2, and 113e can be a complementary color of the color of light emitted by the other light-emitting units.

[0281] For example, the light-emitting units 113a2 and 113e can emit blue light, and the light-emitting unit 113c2 can emit yellow, yellow-green, or green light. For example, the light-emitting units 113a2 and 113e can emit blue light, and the light-emitting unit 113c2 can emit red, green, or yellow-green light. As a result, the light-emitting element 130 can emit white light.

[0282] The charge generation layer 113b2 and the charge generation layer 113d each have at least a charge generation region. The charge generation layer 113b2 has a function of injecting electrons into one of the light-emitting units 113a2 and 113c2 and injecting holes into the other of the light-emitting units 113a2 and 113c2 when a voltage is applied between the pixel electrode of the light-emitting element 130 and the common electrode 115. The charge generation layer 113d has a function of injecting electrons into one of the light-emitting units 113c2 and 113e and injecting holes into the other of the light-emitting units 113c2 and 113e when a voltage is applied between the pixel electrode of the light-emitting element 130 and the common electrode 115.

[0283] Fig. 21A is a modified example of the configuration shown in Fig. 10 , and shows an example in which the subpixel 110R has a colored layer 132R, the subpixel 110G has a colored layer 132G, and the subpixel 110B has a colored layer 132B. In other words, Fig. 21A is an example in which the configuration example shown in Fig. 10 and the configuration example shown in Fig. 19A are combined.

[0284] Fig. 21B is an enlarged cross-sectional view of the insulating layer 127 between the two EL layers 113 shown in Fig. 21A and the surrounding area. Note that Fig. 21B shows conductive layers 112R and 112G as the conductive layer 112. The shapes of the mask layer 118, insulating layer 125, insulating layer 127, etc. shown in Fig. 21B are the same as those in Fig. 11A.

[0285] In a display device according to one embodiment of the present invention, an EL layer is provided in an island shape for each light-emitting element, thereby suppressing lateral leakage current between subpixels. This suppresses crosstalk due to unintended light emission, thereby achieving a display device with extremely high contrast. Furthermore, by providing an insulating layer having a tapered edge between adjacent island-shaped EL layers, the occurrence of discontinuities during the formation of a common electrode can be suppressed, and the formation of locally thin portions in the common electrode can be suppressed. This suppresses connection defects in the common layer and common electrode due to the disconnected portions and increases in electrical resistance due to locally thin portions. This enables the display device according to one embodiment of the present invention to achieve both high resolution and high display quality.

[0286] Next, a light-emitting region of a display device according to one embodiment of the present invention will be described with reference to drawings.

[0287] [Configuration Example 5] Fig. 22A is a modified example of the configuration shown in Fig. 19A. Note that Fig. 22A omits, for example, the microcavity structure described above, and shows an enlarged cross-sectional view of the vicinity of the subpixel 110R and the subpixel 110G shown in Fig. 19A. Fig. 22B is a reference cross-sectional view illustrating the light-emitting region of the display device. Note that Figs. 22A and 22B omit the colored layer 132, the plug 106, and the like.

[0288] 22A illustrates regions 180 and 182 to explain the light-emitting regions of the display device in addition to the configuration described in Fig. 19A. Region 180 functions as the light-emitting region of the display device, and region 182 functions as the non-light-emitting region of the display device.

[0289] In a light-emitting region of a display device, an EL layer is provided between a pair of electrodes (also referred to as between upper and lower electrodes, or between an anode and a cathode). The EL layer includes an island-shaped EL layer 113 and a common layer 114. In Fig. 22A, the EL layer 113 includes a hole-injection layer 113-1, a hole-transport layer 113-2, a light-emitting layer 113-3, and an electron-transport layer 113-4. In Fig. 22A, the common layer 114 functions as an electron-injection layer.

[0290] 22B is a cross-sectional view showing one embodiment of a display device. The display device shown in FIG. 22B includes an insulating layer 105, a conductive layer 111R over the insulating layer 105, a conductive layer 111G over the insulating layer 105, a conductive layer 112R over the conductive layer 111R, a conductive layer 112G over the conductive layer 111G, an insulating layer 127b in contact with the insulating layer 105, the conductive layer 111R, the conductive layer 111G, the conductive layer 112R, and the conductive layer 112G, an EL layer 113 in contact with the insulating layer 127b, the conductive layer 112R, and the conductive layer 112G, a common layer 114 over the EL layer 113, a common electrode 115 over the common layer 114, and a protective layer 131 over the common electrode 115.

[0291] In the light-emitting region of the display device shown in Fig. 22B , an EL layer 113 and a common layer 114 are provided as EL layers between a pair of electrodes. Unlike Fig. 22A , the EL layer 113 shown in Fig. 22B is a continuous film shared by a plurality of light-emitting elements. Note that Fig. 22B illustrates a configuration in which the EL layer 113 includes a hole injection layer 113-1, a hole transport layer 113-2, a light-emitting layer 113-3, and an electron transport layer 113-4. In Fig. 22B , the common layer 114 functions as an electron injection layer.

[0292] 22B , the insulating layer 127b is provided to cover the side surfaces of the conductive layer 111R, the side surfaces of the conductive layer 111G, part of the side surfaces and top surfaces of the conductive layer 112R, and part of the side surfaces and top surfaces of the conductive layer 112G. In this manner, the insulating layer 127b functions as a structure (also referred to as a bank) that covers the side surfaces and part of the top surfaces of the conductive layers. That is, the insulating layer 127b is provided to have regions in contact with the conductive layer 111R, the conductive layer 111G, the conductive layer 112R, and the conductive layer 112G.

[0293] 22B shows a region 184 and a region 186. The region 184 functions as a light-emitting region of the display device, and the region 186 functions as a non-light-emitting region of the display device.

[0294] 22A , in the display device of one embodiment of the present invention, the EL layer 113 (here, the hole-injection layer 113-1, the hole-transport layer 113-2, the light-emitting layer 113-3, and the electron-transport layer 113-4) is provided in an island shape for each light-emitting element, which can suppress lateral leakage current between subpixels. In particular, the hole-injection layer 113-1 of the EL layer 113 is provided in an island shape, which can suitably reduce lateral leakage current between subpixels. Note that the hole-injection layer 113-1 has higher conductivity than the other layers in the EL layer 113. Therefore, it is preferable that at least the hole-injection layer 113-1 be separated between adjacent subpixels as shown in FIG. 22A .

[0295] In addition, in FIG. 22A, in the region 180 functioning as a light-emitting region, the distance (D １ ) and the distance (D ２ More specifically, it is preferable that the difference between the distance (D ２ ) is the distance between a pair of electrodes at the center of the EL layer (D １ ) is preferably less than ±10%, more preferably less than ±3%. １ ) and the distance between the pair of electrodes at the ends of the EL layer (D ２ ) or by eliminating the difference, uniform light emission can be obtained in the light-emitting region.

[0296] On the other hand, as shown in Figure 22B, in a configuration in which the EL layer 113 is provided in common between adjacent sub-pixels, in particular in a configuration in which the hole injection layer 113-1 is used in common between adjacent sub-pixels, there is a possibility that part or all of the region 186 functioning as a non-light-emitting region will emit light. In other words, there is a possibility that a lateral leakage current will occur between the sub-pixels. Also, in Figure 22B, in the region 184 functioning as a light-emitting region, the distance (D ３ ) and the distance (D ４ The difference between the above-mentioned D １ and D ２ will be greater than the difference between

[0297] In FIG. 22B, the distance (D ５ ) is the distance between a pair of electrodes at the ends of the EL layer (D ４ ) in the region 186. ５ ) is a value obtained by adding the film thickness of the EL layer 113, the film thickness of the common layer 114, and the film thickness of the end portion of the insulating layer 127b. For example, when a part of the region 186 functioning as a non-light-emitting region emits light, the distance (D ５ ), light resonates, and therefore the resonance distance of light in region 184 functioning as a light-emitting region is different. Therefore, when region 186 emits light, the resonance distance of light changes from region 184, and therefore one or more of luminance, chromaticity, and light emission direction differ between region 186 and region 184. Furthermore, when light emissions from region 184 functioning as a light-emitting region and region 186 functioning as a non-light-emitting region are mixed, the emission spectrum may become broad or may have a shape with multiple peaks. On the other hand, in the configuration shown in FIG. 22A , light emission from the non-light-emitting region is suppressed, and therefore the emission spectrum may be prevented from becoming broad or having a shape with multiple peaks.

[0298] Furthermore, in display devices, high brightness (for example, 10,000 cd / m ２ ) and low brightness (e.g., 100 cd / m ２ ) is preferable. For this purpose, the structure shown in Figure 22A is more suitable than the structure shown in Figure 22B.

[0299] Fig. 23 is a modified example of the configuration shown in Fig. 21A. Note that Fig. 23 omits, for example, the microcavity structure described above, and shows an enlarged cross-sectional view of the vicinity of the subpixel 110R and the subpixel 110G shown in Fig. 21A. In other words, Fig. 23 is an example in which the configuration shown in Fig. 21A and the configuration shown in Fig. 22A are combined.

[0300] [Manufacturing Method Example 1] Hereinafter, an example of a manufacturing method of the display device 100 having the structure shown in FIG. 2A and the structure shown in FIG. 18A will be described with reference to the drawings.

[0301] Thin films (insulating films, semiconductor films, conductive films, etc.) constituting the display device can be formed using a sputtering method, a chemical vapor deposition (CVD) method, a vacuum evaporation method, a pulsed laser deposition (PLD) method, an ALD method, etc. Examples of 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.

[0302] Furthermore, thin films (insulating films, semiconductor films, conductive films, etc.) constituting the display device can be formed by 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.

[0303] In particular, vacuum processes such as vapor deposition and solution processes such as spin coating and inkjet printing can be used to fabricate light-emitting elements. 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, the EL layer can be formed by vapor deposition (e.g., vacuum deposition), coating methods (dip coating, die coating, bar coating, spin coating, spray coating, etc.), printing methods (inkjet printing, screen (stencil printing), offset (lithographic printing), flexography (relief printing), gravure printing, microcontact printing, etc.), etc.

[0304] 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. Furthermore, the island-shaped thin film may be directly formed by a film formation method using a shielding mask such as a metal mask.

[0305] There are two typical photolithography methods: one is to form a resist mask on a 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 a desired shape by exposure and development.

[0306] For exposure in photolithography, for example, i-line (wavelength 365 nm), g-line (wavelength 436 nm), h-line (wavelength 405 nm), or a mixture of these can be used. Other light sources that can be used include ultraviolet light, KrF laser light, and ArF laser light. Exposure may also be performed using immersion exposure technology. Exposure may also be performed using extreme ultraviolet light (EUV: Extreme Ultra-Violet) or X-rays. An electron beam can also be used instead of 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.

[0307] The thin film can be etched by dry etching, wet etching, sandblasting, or the like.

[0308] To manufacture the display device 100 having the configuration shown in Fig. 2A and the configuration shown in Fig. 18A, first, an insulating layer 101 is formed on a substrate (not shown) as shown in Fig. 24A. Subsequently, conductive layers 102 and 109 are formed on the insulating layer 101, and an insulating layer 103 is formed on the insulating layer 101 so as to cover the conductive layers 102 and 109. Subsequently, an insulating layer 104 is formed on the insulating layer 103, and an insulating layer 105 is formed on the insulating layer 104.

[0309] The substrate may be a substrate having heat resistance sufficient to withstand at least a subsequent heat treatment. When an insulating substrate is used, a glass substrate, a quartz substrate, a sapphire substrate, a ceramic substrate, an organic resin substrate, or the like may be used. Alternatively, a semiconductor substrate such as a single-crystal semiconductor substrate made of silicon or silicon carbide, a polycrystalline semiconductor substrate, a compound semiconductor substrate such as silicon germanium, or an SOI substrate may be used.

[0310] 24A, a cross-sectional view taken along line A1-A2 and a cross-sectional view taken along line B1-B2 are shown side by side, which also applies to subsequent drawings that describe an example of a method for manufacturing a display device.

[0311] 24A, openings are formed in the insulating layers 105, 104, and 103, reaching the conductive layer 102. Then, plugs 106 are formed so as to fill the openings.

[0312] 24A , a conductive film 111f, which will later become the conductive layers 111R, 111G, 111B, and 111C, is formed on the plug 106 and the insulating layer 105. The conductive film 111f can be formed by, for example, sputtering or vacuum deposition. The conductive film 111f can be made of, for example, a metal material.

[0313] The conductive film 111f can have a three-layer structure including, from the bottom, a film that will later become the conductive layer 111a, a film that will later become the conductive layer 111b, and a film that will later become the conductive layer 111c. Alternatively, the conductive film 111f can have a two-layer structure including, from the bottom, a film that will later become the conductive layer 111a and a film that will later become the conductive layer 111b. For example, titanium can be used for the film that will become the conductive layer 111a, aluminum can be used for the film that will become the conductive layer 111b, and titanium can be used for the film that will become the conductive layer 111c. Alternatively, the conductive film 111f can have a single-layer structure.

[0314] 24B , the conductive film 111f is processed by, for example, photolithography to form conductive layers 111R, 111G, 111B, and 111C. Specifically, for example, after forming a resist mask, a portion of the conductive film 111f is removed by etching. When a metal material is used for the conductive film 111f, the conductive film 111f can be removed by, for example, dry etching. Here, when a portion of the conductive film 111f is removed by dry etching, for example, a recess may be formed in a region of the insulating layer 105 that does not overlap with the conductive layer 111.

[0315] The conductive layers 111R, 111G, 111B, and 111C can have a three-layer structure of a conductive layer 111a, a conductive layer 111b on the conductive layer 111a, and a conductive layer 111c on the conductive layer 111b, as shown in Figures 2B1, 2B2, and 4C. The conductive layers 111R, 111G, 111B, and 111C can have a two-layer structure of a conductive layer 111a and a conductive layer 111b on the conductive layer 111a, as shown in Figures 3A, 3B, and 4B. The conductive layers 111R, 111G, 111B, and 111C can have a single-layer structure, as shown in Figure 4A.

[0316] 24C , a conductive film 112f, which will later become the conductive layer 112R, the conductive layer 112G, the conductive layer 112B, and the conductive layer 112C, is formed on the conductive layer 111R, the conductive layer 111G, the conductive layer 111B, the conductive layer 111C, and the insulating layer 105. The conductive film 112f can be formed by, for example, sputtering or vacuum evaporation.

[0317] 2B1 and 3A, the conductive film 112f can be formed using, for example, a conductive oxide. Furthermore, when the conductive layer 112 is formed using the structures shown in FIGS. 2B2 and 3B, the conductive film 112f can have a two-layer structure including, from the bottom, a film that will later become the conductive layer 112a and a film that will later become the conductive layer 112b. For example, a metal material such as titanium, silver, or an alloy containing silver can be used for the film that will become the conductive layer 112a, and a conductive oxide can be used for the film that will become the conductive layer 112b. Furthermore, when the conductive layer 112 is formed using the structures shown in FIGS. 4A, 4B, and 4C, the conductive film 112f can have a three-layer structure including, from the bottom, a film that will later become the conductive layer 112a, a film that will later become the conductive layer 112b, and a film that will later become the conductive layer 112c. For example, a conductive oxide can be used as the film to be the conductive layer 112a, silver or an alloy containing silver can be used as the film to be the conductive layer 112b, and a conductive oxide can be used as the film to be the conductive layer 112c.

[0318] The conductive film 112f can be formed by an ALD method. Here, the conductive film 112f can be an oxide containing one or more elements selected from indium, tin, zinc, gallium, titanium, aluminum, and silicon. In this case, the conductive film 112f can be formed by repeating a cycle that includes introducing a precursor (which may be generally referred to as a precursor or a metal precursor), purging the precursor, introducing an oxidizing agent (which may be generally referred to as a reactant, a reactant, a non-metal precursor, or the like), and purging the oxidizing agent. Here, when an oxide film containing multiple types of metals, such as indium tin oxide, is formed as the conductive film 112f, the metal composition can be controlled by varying the number of cycles for each type of precursor.

[0319] For example, when forming an indium tin oxide film as the conductive film 112f, an indium-containing precursor is introduced, the precursor is purged, an oxidizing agent is introduced, and an In—O film is formed. Next, a tin-containing precursor is introduced, the precursor is purged, and an oxidizing agent is introduced, and an Sn—O film is formed. Here, by making the number of cycles for forming the In—O film larger than the number of cycles for forming the Sn—O film, the number of In atoms contained in the conductive film 112f can be made larger than the number of Sn atoms.

[0320] Furthermore, for example, when a zinc oxide film is formed as the conductive film 112f, a Zn—O film is formed using the above procedure. For example, when an aluminum zinc oxide film is formed as the conductive film 112f, a Zn—O film and an Al—O film are formed using the above procedure. For example, when a titanium oxide film is formed as the conductive film 112f, a Ti—O film is formed using the above procedure. For example, when an indium tin oxide film containing silicon is formed as the conductive film 112f, an In—O film, an Sn—O film, and an Si—O film are formed using the above procedure. For example, when a zinc oxide film containing gallium is formed as the conductive film 112f, a Ga—O film and a Zn—O film are formed using the above procedure.

[0321] Examples of indium-containing precursors include triethylindium, trimethylindium, and [1,1,1-trimethyl-N-(trimethylsilyl)amido]-indium. Examples of tin-containing precursors include tin chloride and tetrakis(dimethylamido)tin. Examples of zinc-containing precursors include diethylzinc and dimethylzinc. Examples of gallium-containing precursors include triethylgallium. Examples of titanium-containing precursors include titanium chloride, tetrakis(dimethylamido)titanium, and tetraisopropyl titanate. Examples of aluminum-containing precursors include aluminum chloride and trimethylaluminum. Examples of silicon-containing precursors include trisilylamine, bis(diethylamino)silane, tris(dimethylamino)silane, bis(tert-butylamino)silane, and bis(ethylmethylamino)silane. Examples of oxidizing agents include water vapor, oxygen plasma, and ozone gas.

[0322] Here, for example, after the formation of the conductive layer 111 and before the formation of the conductive film 112f, the surface of the conductive layer 111 may be oxidized. For example, when the conductive layer 111 is exposed to the atmosphere after its formation, the surface of the conductive layer 111 may be oxidized due to oxygen contained in the atmosphere. Here, when a metal whose electrical resistivity increases upon oxidation is used for the uppermost layer of the conductive layer 111, the electrical resistance at the contact interface between the conductive layer 111 and the conductive layer 112 may be higher than when the surface of the conductive layer 111 is not oxidized. This may cause defects in the manufactured display device, resulting in a display device with low reliability.

[0323] Therefore, it is preferable to remove the oxide on the surface of the conductive layer 111 after forming the conductive layer 111 and before forming the conductive film 112f. Then, after removing the oxide, it is preferable to form the conductive film 112f without exposing the conductive layer 111 to the atmosphere. This reduces the electrical resistance at the contact interface between the conductive layer 111 and the conductive layer 112. This prevents defects from occurring in the display device 100, making the display device 100 a highly reliable display device. The oxide on the surface of the conductive layer 111 can be removed by, for example, a reverse sputtering method.

[0324] The inverse sputtering method is a method of modifying a surface to be treated by bombarding ions onto the surface to be treated, instead of bombarding ions onto a sputtering target as in conventional sputtering. One method of bombarding ions onto the surface to be treated is to apply a high-frequency voltage to the surface to be treated in a gas atmosphere containing a Group 18 element such as argon, thereby generating plasma near the surface to be treated. Note that instead of the gas atmosphere containing a Group 18 element, an atmosphere containing nitrogen, oxygen, or the like may also be used. The apparatus used in the inverse sputtering method is not limited to a sputtering apparatus; similar processing can be performed using a plasma CVD apparatus, a dry etching apparatus, or the like.

[0325] Next, as shown in FIG. 24D , the conductive film 112f is processed by, for example, photolithography to form conductive layers 112R, 112G, 112B, and 112C. Specifically, for example, after forming a resist mask, a portion of the conductive film 112f is removed by etching. When a conductive oxide is used as the conductive film 112f, the conductive film 112f can be removed by, for example, wet etching. The conductive layer 112 is formed to cover the top and side surfaces of the conductive layer 111. Note that, for example, when the conductive layer 112 has the structure shown in FIG. 2B2 and the conductive layer 112a is made of a metal material and the conductive layer 112b is made of a conductive oxide, a portion of the conductive film that will become the conductive layer 112b can be removed by wet etching, and then a portion of the conductive film that will become the conductive layer 112a can be removed by dry etching. Note that a portion of the conductive film that will become the conductive layer 112a may be removed by wet etching, or a portion of the conductive film that will become the conductive layer 112b may be removed by dry etching.

[0326] Here, when the conductive layer 112 has a stacked structure of the conductive layer 112a and the conductive layer 112b as shown in FIGS. 2B2 and 3B, a metal material such as titanium, silver, or an alloy containing silver can be used for the film that becomes the conductive layer 112a included in the conductive film 112f. Furthermore, a conductive oxide such as indium tin oxide can be used for the film that becomes the conductive layer 112b included in the conductive film 112f. As described above, by using silver or an alloy containing silver for the conductive layer 112a, the reflectivity of the pixel electrode for visible light can be increased. On the other hand, as described above, titanium has better etching processability than silver. Therefore, by using titanium for the film that becomes the conductive layer 112a, the film can be easily processed to form the conductive layer 112a.

[0327] Subsequently, it is preferable to perform hydrophobic treatment on the conductive layer 112. The hydrophobic treatment can change the surface to be treated from hydrophilic to hydrophobic, or can increase the hydrophobicity of the surface to be treated. By performing the hydrophobic treatment on the conductive layer 112, adhesion between the conductive layer 112 and the EL layer 113 formed in a later step can be increased, and film peeling can be suppressed. Note that the hydrophobic treatment is not necessarily performed.

[0328] The hydrophobic treatment can be performed by, for example, modifying the conductive layer 112 with fluorine. The fluorine modification can be performed by, for example, a treatment using a gas containing fluorine, a heat treatment, or a plasma treatment in a gas atmosphere containing fluorine. As the gas containing fluorine, for example, a fluorine gas can be used, such as a fluorocarbon gas. As the fluorocarbon gas, for example, carbon tetrafluoride (CF ４ ) Gas, C ４ F ６ Gas, C ２ F ６ Gas, C ４ F ８ Gas or C ５ F ８ As a gas containing fluorine, for example, SF ６ Gas, NF ３ gas, or CHF ３ Gases such as helium gas, argon gas, hydrogen gas, or oxygen gas can be added to these gases as appropriate.

[0329] Furthermore, the surface of the conductive layer 112 can be hydrophobized by performing plasma treatment on the surface of the conductive layer 112 in a gas atmosphere containing a Group 18 element such as argon, followed by treatment using a silylating agent. Hexamethyldisilazane (HMDS), trimethylsilylimidazole (TMSI), or the like can be used as the silylating agent. Furthermore, the surface of the conductive layer 112 can also be hydrophobized by performing plasma treatment on the surface of the conductive layer 112 in a gas atmosphere containing a Group 18 element such as argon, followed by treatment using a silane coupling agent.

[0330] By performing plasma treatment on the surface of the conductive layer 112 in a gas atmosphere containing a Group 18 element such as argon, it is possible to damage the surface of the conductive layer 112. This makes it easier for methyl groups contained in a silylating agent such as HMDS to bond to the surface of the conductive layer 112. Furthermore, silane coupling by a silane coupling agent is more likely to occur. As described above, by performing plasma treatment on the surface of the conductive layer 112 in a gas atmosphere containing a Group 18 element such as argon and then performing treatment using a silylating agent or a silane coupling agent, it is possible to hydrophobize the surface of the conductive layer 112.

[0331] The treatment using a silylating agent, a silane coupling agent, or the like can be performed by applying the silylating agent, the silane coupling agent, or the like using, for example, a spin coating method or a dipping method. Alternatively, the treatment using a silylating agent, the silane coupling agent, or the like can be performed by, for example, using a vapor phase method to form a film containing a silylating agent, a film containing a silane coupling agent, or the like on the conductive layer 112, or the like. In the vapor phase method, first, a material containing a silylating agent, a material containing a silane coupling agent, or the like is volatilized to incorporate the silylating agent, the silane coupling agent, or the like into an atmosphere. Next, a substrate on which the conductive layer 112, for example, is formed is placed in the atmosphere. This allows a film containing the silylating agent, the silane coupling agent, or the like to be formed on the conductive layer 112, thereby making the surface of the conductive layer 112 hydrophobic.

[0332] Subsequently, as shown in FIG. 25A, an EL film 113Rf, which will later become the EL layer 113R, is formed on the conductive layer 112R, the conductive layer 112G, the conductive layer 112B, and the insulating layer 105.

[0333] 25A , the EL film 113Rf is not formed on the conductive layer 112C. For example, by using an area mask, the EL film 113Rf can be formed only in a desired region. By employing a film formation process using an area mask and a processing process using a resist mask, the light-emitting element can be fabricated through a relatively simple process.

[0334] The EL film 113Rf can be formed by, for example, a vapor deposition method, specifically a vacuum deposition method. Alternatively, the EL film 113Rf may be formed by a transfer method, a printing method, an inkjet method, a coating method, or the like.

[0335] 25A, a mask film 118Rf that will later become the mask layer 118R and a mask film 119Rf that will later become the mask layer 119R are formed in this order on the EL film 113Rf, the conductive layer 112C, and the insulating layer 105.

[0336] In this embodiment, an example is shown in which the mask film is formed with a two-layer structure of the mask film 118Rf and the mask film 119Rf, but the mask film may have a single-layer structure or a laminated structure of three or more layers.

[0337] By providing a mask layer on the EL film 113Rf, damage to the EL film 113Rf during the manufacturing process of the display device can be reduced, and the reliability of the light-emitting element can be improved.

[0338] The mask film 118Rf is made of a film that is highly resistant to the processing conditions of the EL film 113Rf, specifically, a film that has a large etching selectivity with respect to the EL film 113Rf.The mask film 119Rf is made of a film that has a large etching selectivity with respect to the mask film 118Rf.

[0339] The mask films 118Rf and 119Rf are formed at a temperature lower than the heat-resistant temperature of the EL film 113Rf. The substrate temperature when forming the mask films 118Rf and 119Rf 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.

[0340] It is preferable to use a film that can be removed by wet etching for the mask films 118Rf and 119Rf. By using wet etching, damage to the EL film 113Rf during processing of the mask films 118Rf and 119Rf can be reduced compared to when dry etching is used.

[0341] The mask films 118Rf and 119Rf can be formed by, for example, sputtering, ALD (thermal ALD or PEALD), CVD, or vacuum deposition. Alternatively, they may be formed by the wet film formation method described above.

[0342] The mask film 118Rf formed on and in contact with the EL film 113Rf is preferably formed using a formation method that causes less damage to the EL film 113Rf than the mask film 119Rf. For example, it is preferable to form the mask film 118Rf using the ALD method or the vacuum deposition method rather than the sputtering method.

[0343] The mask film 118Rf and the mask film 119Rf may each be made of 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, or the like.

[0344] The mask films 118Rf and 119Rf 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 rays for one or both of the mask films 118Rf and 119Rf is preferable because it can prevent ultraviolet rays from being irradiated onto the EL film 113Rf and suppress deterioration of the EL film 113Rf.

[0345] Furthermore, the mask film 118Rf and the mask film 119Rf may each be made of a metal oxide such as In—Ga—Zn oxide, indium oxide, In—Zn oxide, In—Sn oxide, indium titanium oxide (In—Ti oxide), indium tin zinc oxide (In—Sn—Zn oxide), indium titanium zinc oxide (In—Ti—Zn oxide), indium gallium tin zinc oxide (In—Ga—Sn—Zn oxide), or indium tin oxide containing silicon.

[0346] 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.

[0347] Furthermore, a film containing a material that has light-shielding properties, particularly against ultraviolet light, can be used as the mask film. For example, a film that is reflective to ultraviolet light or a film that absorbs ultraviolet light can be used. As the light-shielding material, various materials can be used, such as metals, insulators, semiconductors, and semimetals that have light-shielding properties against ultraviolet light. However, since part or all of the mask film will be removed in a later step, it is preferable that the mask film be a film that can be processed by etching, and particularly that it has good processability.

[0348] For example, materials that are highly compatible with semiconductor manufacturing processes include semiconductor materials such as silicon and germanium. Also, oxides and nitrides of the above semiconductor materials are included. Also, nonmetallic (semimetallic) materials such as carbon and their compounds are included. Also, metals such as titanium, tantalum, tungsten, chromium, and aluminum, as well as alloys containing one or more of these, are included. Also, oxides containing the above metals, such as titanium oxide and chromium oxide, and nitrides such as titanium nitride, chromium nitride, and tantalum nitride are included.

[0349] By using a film containing a material having a light-shielding property against ultraviolet rays as the mask film, it is possible to prevent the EL layer from being irradiated with ultraviolet rays during, for example, an exposure process, and by preventing the EL layer from being damaged by ultraviolet rays, the reliability of the light-emitting element can be improved.

[0350] The film containing a material that blocks ultraviolet light can also provide the same effect when used as the insulating film 125f described later.

[0351] Furthermore, the mask films 118Rf and 119Rf 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 film 113Rf than nitride insulating films. For example, the mask films 118Rf and 119Rf can each be made of inorganic insulating materials such as aluminum oxide, hafnium oxide, or silicon oxide. For example, aluminum oxide films can be formed as the mask films 118Rf and 119Rf using the ALD method. Using the ALD method is preferable because it reduces damage to the underlying layer, especially the EL layer.

[0352] For example, the mask film 118Rf can be an inorganic insulating film formed using the ALD method, such as an aluminum oxide film, and the mask film 119Rf can be an inorganic film formed using the sputtering method, such as an In-Ga-Zn oxide film, an aluminum film, or a tungsten film.

[0353] The same inorganic insulating film can be used for both the mask film 118Rf 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 118Rf and the insulating layer 125. The mask film 118Rf and the insulating layer 125 may be formed under the same or different film-forming conditions. For example, by forming the mask film 118Rf under the same conditions as the insulating layer 125, the mask film 118Rf can be an insulating film with high barrier properties against at least one of water and oxygen. On the other hand, since the mask film 118Rf is a layer that will be largely or completely removed in a later process, it is preferable that it be easily processed. For this reason, the mask film 118Rf is preferably formed under conditions where the substrate temperature during film formation is lower than that of the insulating layer 125.

[0354] An organic material may be used for one or both of the mask films 118Rf and 119Rf. For example, a material that can be dissolved in a chemically stable solvent may be used as the organic material. In particular, a material that can be dissolved in water or alcohol is preferably used. 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 the solvent can be removed at a low temperature and in a short time, thereby reducing thermal damage to the EL film 113Rf.

[0355] The mask film 118Rf and the mask film 119Rf may each be made of an organic resin such as polyvinyl alcohol (PVA), polyvinyl butyral, polyvinylpyrrolidone, polyethylene glycol, polyglycerin, pullulan, water-soluble cellulose, alcohol-soluble polyamide resin, or a fluororesin such as a perfluoropolymer.

[0356] For example, the mask film 118Rf may be an organic film (e.g., a PVA film) formed using either a vapor deposition method or the above-mentioned wet film formation method, and the mask film 119Rf may be an inorganic film (e.g., a silicon nitride film) formed using a sputtering method.

[0357] Note that in the display device according to one embodiment of the present invention, part of the mask film may remain as a mask layer.

[0358] 25A, a resist mask 190R is formed on the mask film 119Rf. The resist mask 190R can be formed by applying a photosensitive material (photoresist) and then performing exposure and development.

[0359] The resist mask 190R may be made of either a positive resist material or a negative resist material.

[0360] The resist mask 190R is provided in a position overlapping with the conductive layer 112R. The resist mask 190R is preferably also provided in a position overlapping with the conductive layer 112C. This can prevent the conductive layer 112C from being damaged during the manufacturing process of the display device. Note that the resist mask 190R does not necessarily have to be provided on the conductive layer 112C. Furthermore, as shown in the cross-sectional view between B1 and B2 in FIG. 25A , the resist mask 190R is preferably provided so as to cover from the end of the EL film 113Rf to the end of the conductive layer 112C on the EL film 113Rf side.

[0361] 25A and 25B, a resist mask 190R is used to remove a portion of the mask film 119Rf to form a mask layer 119R. The mask layer 119R remains on the conductive layer 112R and the conductive layer 112C. The resist mask 190R is then removed. The mask layer 119R is used as a mask (also referred to as a hard mask) to remove a portion of the mask film 118Rf to form a mask layer 118R.

[0362] The mask films 118Rf and 119Rf can be processed by wet etching or dry etching, respectively, and are preferably processed by anisotropic etching.

[0363] By using the wet etching method, damage to the EL film 113Rf during processing of the mask films 118Rf and 119Rf can be reduced compared to when using the dry etching method. When using the wet etching method, it is preferable to use a chemical solution using, for example, a developer, a tetramethylammonium hydroxide aqueous solution (TMAH), dilute hydrofluoric acid, oxalic acid, phosphoric acid, acetic acid, nitric acid, or a mixture thereof.

[0364] Since the EL film 113Rf is not exposed when processing the mask film 119Rf, the range of processing method options is wider than when processing the mask film 118Rf. Specifically, when a gas containing oxygen is used as an etching gas when processing the mask film 119Rf, deterioration of the EL film 113Rf can be suppressed more effectively than when a gas containing oxygen is used as an etching gas when processing the mask film 118Rf.

[0365] Furthermore, when dry etching is used to process the mask film 118Rf, deterioration of the EL film 113Rf can be suppressed by not using a gas containing oxygen as the etching gas. ４ , C ４ F ８ , S.F. ６ , CHF ３ , Cl ２ , H ２ O, BCl ３ It is preferable to use, as the etching gas, a gas containing an element of Group 18. As the element of Group 18, for example, He can be used.

[0366] For example, when an aluminum oxide film formed by the ALD method is used as the mask film 118Rf, CHF ３ and He, or CHF ３ and He and CH ４ In addition, when an In—Ga—Zn oxide film formed by sputtering is used as the mask film 119Rf, a portion of the mask film 119Rf can be removed by wet etching using diluted phosphoric acid. ４ A part of the mask film 119Rf may be removed by dry etching using Ar. Alternatively, a part of the mask film 119Rf may be removed by wet etching using diluted phosphoric acid. In addition, when a tungsten film formed by sputtering is used as the mask film 119Rf, SF ６ , C.F. ４ and O ２ , or CF ４ and Cl ２ and O ２ Using this, a part of the mask film 119Rf can be removed by dry etching.

[0367] The resist mask 190R can be removed by, for example, ashing using oxygen plasma. Alternatively, ashing using oxygen gas and CF ４ , C ４ F ８ , S.F.６ , CHF ３ , Cl ２ , H ２ O, BCl ３ , or a Group 18 element may be used. As the Group 18 element, for example, He may be used. Alternatively, the resist mask 190R may be removed by wet etching. At this time, the mask film 118Rf is located on the outermost surface and the EL film 113Rf is not exposed, so that damage to the EL film 113Rf can be suppressed in the process of removing the resist mask 190R. Furthermore, the range of options for removing the resist mask 190R can be expanded.

[0368] 25A and 25B, the EL film 113Rf is processed to form the EL layer 113R. For example, the EL film 113Rf is partially removed using the mask layer 119R and the mask layer 118R as a mask to form the EL layer 113R.

[0369] 25B, a laminated structure of the EL layer 113R, the mask layer 118R, and the mask layer 119R remains on the conductive layer 112R, and the conductive layers 112G and 112B are exposed.

[0370] 25B shows an example in which the edge of the EL layer 113R is positioned outside the edge of the conductive layer 112R. This configuration can increase the aperture ratio of the pixel. Although not shown in FIG. 25B , the etching process may result in the formation of a recess in a region of the insulating layer 105 that does not overlap with the EL layer 113R.

[0371] Furthermore, because the EL layer 113R covers the top and side surfaces of the conductive layer 112R, subsequent processes can be performed without exposing the conductive layer 112R. If the edges of the conductive layer 112R are exposed, corrosion may occur, for example, during an etching process. Products resulting from corrosion of the conductive layer 112R may be unstable, dissolving in solution during wet etching or scattering into the atmosphere during dry etching. Dissolving the products into solution or scattering into the atmosphere can result in the products adhering to the processed surface and the side surfaces of the EL layer 113R, potentially adversely affecting the characteristics of light-emitting elements or forming leak paths between multiple light-emitting elements. Furthermore, in areas where the edges of the conductive layer 112R are exposed, adhesion between adjacent layers may be reduced, potentially making the EL layer 113R or the conductive layer 112R more susceptible to peeling.

[0372] Therefore, by using a structure in which the EL layer 113R covers the top surface and side surfaces of the conductive layer 112R, for example, the yield and characteristics of the light-emitting element can be improved.

[0373] As described above, the resist mask 190R is preferably provided between B1 and B2 so as to cover from the end of the EL layer 113R to the end of the conductive layer 112C on the EL layer 113R side. As shown in FIG. 25B , the mask layer 118R and the mask layer 119R are provided between B1 and B2 so as to cover from the end of the EL layer 113R to the end of the conductive layer 112C on the EL layer 113R side. This prevents the insulating layer 105 from being exposed between B1 and B2, for example. This prevents portions of the insulating layer 105, the insulating layer 104, and the insulating layer 103 from being removed by etching or the like, thereby preventing the conductive layer 109 from being exposed. This prevents the conductive layer 109 from being unintentionally electrically connected to other conductive layers. For example, this prevents a short circuit between the conductive layer 109 and the common electrode 115 formed in a later process.

[0374] The EL film 113Rf is preferably processed by anisotropic etching, particularly anisotropic dry etching, or wet etching may be used.

[0375] When dry etching is used, deterioration of the EL film 113Rf can be suppressed by not using a gas containing oxygen as the etching gas.

[0376] Alternatively, a gas containing oxygen may be used as the etching gas. The inclusion of oxygen in the etching gas can increase the etching rate. Therefore, etching can be performed under low power conditions while maintaining a sufficiently high etching rate. This can reduce damage to the EL film 113Rf. Furthermore, problems such as adhesion of reaction products that occur during etching can be reduced.

[0377] When dry etching is used, for example, H ２ , C.F. ４ , C ４ F ８ , S.F. ６ , CHF ３ , Cl ２ , H ２ O, BCl ３ It is preferable to use a gas containing one or more of Group 18 elements such as He or Ar as the etching gas. Alternatively, it is preferable to use a gas containing one or more of these elements 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 H, He, and oxygen can be used as the etching gas. ２ A gas containing Ar and a gas containing oxygen can be used as the etching gas.

[0378] As described above, in one embodiment of the present invention, the resist mask 190R is formed over the mask film 119Rf, and part of the mask film 119Rf is removed using the resist mask 190R to form the mask layer 119R. Then, part of the EL film 113Rf is removed using the mask layer 119R as a mask to form the EL layer 113R. Therefore, it can be said that the EL layer 113R is formed by processing the EL film 113Rf using a photolithography method. Note that part of the EL film 113Rf may be removed using the resist mask 190R. Then, the resist mask 190R may be removed.

[0379] Next, it is preferable to perform a hydrophobic treatment on the conductive layer 112G, for example. During processing of the EL film 113Rf, for example, the surface state of the conductive layer 112G may change to a hydrophilic state. By performing the hydrophobic treatment on the conductive layer 112G, for example, the adhesion between the conductive layer 112G and a layer (here, the EL layer 113G) formed in a later process can be improved, and film peeling can be suppressed. Note that the hydrophobic treatment is not necessarily required.

[0380] 25C, an EL film 113Gf, which will later become the EL layer 113G, is formed on the conductive layer 112G, the conductive layer 112B, the mask layer 119R, and the insulating layer 105. Then, as shown in FIG.

[0381] The EL film 113Gf can be formed by a method similar to that used to form the EL film 113Rf.

[0382] 25C , a mask film 118Gf, which will later become the mask layer 118G, and a mask film 119Gf, which will later become the mask layer 119G, are sequentially formed on the EL film 113Gf and the mask layer 119R. A resist mask 190G is then formed. The materials and formation methods for the mask films 118Gf and 119Gf are the same as those applicable to the mask films 118Rf and 119Rf. The materials and formation methods for the resist mask 190G are the same as those applicable to the resist mask 190R.

[0383] The resist mask 190G is provided in a position overlapping with the conductive layer 112G.

[0384] 25C and 25D, a resist mask 190G is used to remove a portion of the mask film 119Gf to form a mask layer 119G. The mask layer 119G remains on the conductive layer 112G. The resist mask 190G is then removed. Next, using the mask layer 119G as a mask, a portion of the mask film 118Gf is removed to form a mask layer 118G. Next, the EL film 113Gf is processed to form the EL layer 113G. For example, using the mask layer 119G and the mask layer 118G as masks, a portion of the EL film 113Gf is removed to form the EL layer 113G.

[0385] 25D, a laminated structure of the EL layer 113G, the mask layer 118G, and the mask layer 119G remains on the conductive layer 112G, and the mask layer 119R and the conductive layer 112B are exposed.

[0386] Next, it is preferable to perform, for example, a hydrophobic treatment on the conductive layer 112B. During processing of the EL film 113Gf, for example, the surface state of the conductive layer 112B may change to a hydrophilic state. For example, by performing the hydrophobic treatment on the conductive layer 112B, it is possible to increase the adhesion between the conductive layer 112B and a layer (here, the EL layer 113B) formed in a later process, and to suppress film peeling. Note that the hydrophobic treatment is not necessarily required.

[0387] Subsequently, as shown in FIG. 26A, an EL film 113Bf, which will later become the EL layer 113B, is formed on the conductive layer 112B, the mask layer 119R, the mask layer 119G, and the insulating layer 105.

[0388] The EL film 113Bf can be formed by a method similar to that used to form the EL film 113Rf.

[0389] 26A , a mask film 118Bf, which will later become the mask layer 118B, and a mask film 119Bf, which will later become the mask layer 119B, are sequentially formed on the EL film 113Bf and the mask layer 119R. A resist mask 190B is then formed. The materials and formation methods for the mask films 118Bf and 119Bf are the same as those applicable to the mask films 118Rf and 119Rf. The materials and formation methods for the resist mask 190B are the same as those applicable to the resist mask 190R.

[0390] The resist mask 190B is provided in a position overlapping with the conductive layer 112B.

[0391] 26A and 26B, a resist mask 190B is used to remove a portion of the mask film 119Bf to form a mask layer 119B. The mask layer 119B remains on the conductive layer 112B. The resist mask 190B is then removed. Next, using the mask layer 119B as a mask, a portion of the mask film 118Bf is removed to form a mask layer 118B. Next, the EL film 113Bf is processed to form the EL layer 113B. For example, using the mask layer 119B and the mask layer 118B as masks, a portion of the EL film 113Bf is removed to form the EL layer 113B.

[0392] 26B, a laminated structure of the EL layer 113B, the mask layer 118B, and the mask layer 119B remains on the conductive layer 112B, and the mask layers 119R and 119G are exposed.

[0393] The side surfaces of the EL layers 113R, 113G, and 113B are preferably perpendicular or substantially 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.

[0394] As described above, the distance between any two adjacent EL layers 113R, 113G, and 113B formed using photolithography 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 can be defined, for example, as the distance between the opposing ends of any two adjacent EL layers 113R, 113G, and 113B. By narrowing the distance between the island-shaped EL layers 113 in this manner, a display device with high definition and a large aperture ratio can be provided.

[0395] 26C , it is preferable to remove mask layers 119R, 119G, and 119B. Depending on the subsequent process, mask layers 118R, 118G, 118B, 119R, 119G, and 119B may remain on the display device. By removing mask layers 119R, 119G, and 119B at this stage, it is possible to prevent mask layers 119R, 119G, and 119B from remaining on the display device. For example, if a conductive material is used for mask layers 119R, 119G, and 119B, removing mask layers 119R, 119G, and 119B in advance can prevent leakage current and capacitance from remaining mask layers 119R, 119G, and 119B.

[0396] In the present embodiment, the case where the mask layers 119R, 119G, and 119B are removed will be described as an example, but the mask layers 119R, 119G, and 119B do not necessarily have to be removed. For example, if the mask layers 119R, 119G, and 119B contain the aforementioned material that is light-blocking to ultraviolet light, it is preferable to proceed to the next step without removing them, because this can protect the EL layer 113 from ultraviolet light.

[0397] The mask layer removal step can be performed using the same method as the mask layer processing step. In particular, by using a wet etching method, damage to the EL layers 113R, 113G, and 113B during mask layer removal can be reduced compared to when a dry etching method is used.

[0398] The mask layer may also be removed by dissolving it in a solvent such as water or alcohol, such as ethyl alcohol, methyl alcohol, isopropyl alcohol (IPA), or glycerin.

[0399] After removing the mask layer, a drying treatment may be performed to remove water contained in the EL layer 113R, the EL layer 113G, and the EL layer 113B, as well as water adsorbed to the surfaces of the EL layer 113R, the EL layer 113G, and the EL layer 113B. 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 preferable because it enables drying at a lower temperature.

[0400] Subsequently, as shown in FIG. 26D, an insulating film 125f, which will later become the insulating layer 125, is formed to cover the EL layer 113R, the EL layer 113G, the EL layer 113B, the mask layer 118R, the mask layer 118G, and the mask layer 118B.

[0401] As will be described later, an insulating film that will later become the insulating layer 127 is formed in contact with the upper surface of the insulating film 125f. Therefore, it is preferable that the upper surface of the insulating film 125f has a high affinity with the material used for the insulating film, such as a photosensitive resin composition containing an acrylic resin. To improve this affinity, it is preferable to perform a surface treatment to hydrophobize or increase the hydrophobicity of the upper surface of the insulating film 125f. For example, it is preferable to perform the treatment using a silylating agent such as HMDS. By hydrophobizing the upper surface of the insulating film 125f in this manner, the insulating film 127f can be formed with good adhesion. The surface treatment may also be the hydrophobization treatment described above.

[0402] Subsequently, as shown in FIG. 27A, an insulating film 127f, which will later become the insulating layer 127, is formed on the insulating film 125f.

[0403] The insulating films 125f and 127f are preferably formed by a formation method that causes less damage to the EL layers 113R, 113G, and 113B. In particular, since the insulating film 125f is formed in contact with the side surfaces of the EL layers 113R, 113G, and 113B, it is preferably formed by a formation method that causes less damage to the EL layers 113R, 113G, and 113B than the insulating film 127f.

[0404] The insulating films 125f and 127f are formed at a temperature lower than the heat-resistant temperatures of the EL layer 113R, the EL layer 113G, and the EL layer 113B, respectively. By increasing the substrate temperature during film formation, the insulating film 125f can have a low impurity concentration and a high barrier property against at least one of water and oxygen, even if it is thin.

[0405] The substrate temperature when forming the insulating films 125f and 127f is preferably 60°C or higher, 80°C or higher, 100°C or higher, or 120°C or higher, and 200°C or lower, 180°C or lower, 160°C or lower, 150°C or lower, or 140°C or lower.

[0406] The insulating film 125f is preferably formed to a thickness of 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 within the above substrate temperature range.

[0407] The insulating film 125f is preferably formed by, for example, an ALD method. The ALD method is preferable because it can reduce film formation damage and form a film with high coverage. The insulating film 125f is preferably formed as an aluminum oxide film by, for example, an ALD method.

[0408] Alternatively, the insulating film 125f may be formed by a sputtering method, a CVD method, or a PECVD method, which have a faster film formation rate than an ALD method. This enables a highly reliable display device to be manufactured with high productivity.

[0409] The insulating film 127f is preferably formed by the wet film formation method described above. For example, the insulating film 127f is preferably formed by spin coating using a photosensitive material, more specifically, using a photosensitive resin composition containing an acrylic resin.

[0410] The insulating film 127f is preferably formed using, for example, a resin composition containing a polymer, an acid generator, and a solvent. The polymer is formed using one or more types of monomers and has a structure in which one or more types of structural units (also referred to as constituent units) are regularly or irregularly repeated. As the acid generator, one or both of a compound that generates an acid upon irradiation with light and a compound that generates an acid upon heating can be used. The resin composition may further contain one or more of a photosensitizer, a sensitizer, a catalyst, an adhesion aid, a surfactant, and an antioxidant.

[0411] Furthermore, heat treatment (also referred to as pre-baking) is preferably performed after the insulating film 127f is formed. The heat treatment is performed at a temperature lower than the heat resistance temperature of the EL layer 113R, the EL layer 113G, and the EL layer 113B. The substrate temperature during the heat treatment is preferably 50° C. or higher and 200° C. or lower, more preferably 60° C. or higher and 150° C. or lower, and further preferably 70° C. or higher and 120° C. or lower. This allows the solvent contained in the insulating film 127f to be removed.

[0412] Next, exposure is performed to expose a portion of the insulating film 127f to visible light or ultraviolet light. If a positive-type photosensitive resin composition containing an acrylic resin is used for the insulating film 127f, visible light or ultraviolet light is irradiated onto the region where the insulating layer 127 will not be formed in a later process. The insulating layer 127 is formed in the region sandwiched between any two of the conductive layers 112R, 112G, and 112B, as well as around the conductive layer 112C. Therefore, visible light or ultraviolet light is irradiated onto the conductive layers 112R, 112G, 112B, and 112C. If a negative-type photosensitive material is used for the insulating film 127f, visible light or ultraviolet light is irradiated onto the region where the insulating layer 127 will be formed.

[0413] The width of the insulating layer 127 to be formed later can be controlled by the exposed region of the insulating film 127f. In this embodiment mode, the insulating layer 127 is processed to have a portion overlapping with the top surface of the conductive layer 111.

[0414] The light used for exposure preferably contains i-line (wavelength 365 nm), and may contain at least one of g-line (wavelength 436 nm) and h-line (wavelength 405 nm).

[0415] Here, by providing an oxygen barrier insulating layer, such as an aluminum oxide film, as one or both of the mask layer 118 and the insulating film 125f, it is possible to reduce the diffusion of oxygen into the EL layer 113R, the EL layer 113G, and the EL layer 113B. When the EL layer is irradiated with light (visible light or ultraviolet light), the organic compounds contained in the EL layer are excited, which may promote a reaction with oxygen contained in the atmosphere. More specifically, when the EL layer is irradiated with light (visible light or ultraviolet light) in an oxygen-containing atmosphere, oxygen may bond to the organic compounds contained in the EL layer. By providing the mask layer 118 and the insulating film 125f on the island-shaped EL layer, it is possible to reduce the bonding of oxygen in the atmosphere to the organic compounds contained in the EL layer.

[0416] 27B1 and 27B2, development is performed to remove the exposed areas of the insulating film 127f, forming an insulating layer 127a. Note that FIG. 27B2 is an enlarged view of the EL layer 113G and the edge and vicinity of the insulating layer 127a shown in FIG. 27B1. The insulating layer 127a is formed in a region sandwiched between any two of the conductive layers 112R, 112G, and 112B, and in a region surrounding the conductive layer 112C. When an acrylic resin is used for the insulating film 127f, an alkaline solution, such as TMAH, is preferably used as the developer.

[0417] Subsequently, residues (so-called scum) remaining after development may be removed, for example, by ashing using oxygen plasma.

[0418] Etching may be performed to adjust the height of the surface of the insulating layer 127a. The insulating layer 127a may be processed by ashing using oxygen plasma, for example. Even when a non-photosensitive material is used as the insulating film 127f, the height of the surface of the insulating film 127f can be adjusted by ashing, for example.

[0419] Next, as shown in Figures 28A and 28B, an etching process is performed using the insulating layer 127a as a mask to remove a portion of the insulating film 125f and thin the film thickness of portions of the mask layers 118R, 118G, and 118B. This results in the formation of the insulating layer 125 below the insulating layer 127a. Furthermore, the surfaces of the thin portions of the mask layers 118R, 118G, and 118B are exposed. Note that Figure 28B is an enlarged view of the EL layer 113G and the end and vicinity of the insulating layer 127a shown in Figure 28A. Note that hereinafter, the etching process using the insulating layer 127a as a mask may be referred to as the first etching process.

[0420] The first etching treatment can be performed by dry etching or wet etching. Note that it is preferable to form the insulating film 125f using the same material as the mask layers 118R, 118G, and 118B because the first etching treatment can be performed simultaneously.

[0421] As shown in FIG. 28B, by performing etching using insulating layer 127a, which has tapered side surfaces, as a mask, the side surfaces of insulating layer 125 and the upper end portions of the side surfaces of mask layers 118R, 118G, and 118B can be tapered relatively easily.

[0422] When dry etching is performed, it is preferable to use a chlorine-based gas. ２ , BCl ３ , SiCl ４ , and CCl ４The chlorine-based gas may be added alone or in combination with two or more gases selected from oxygen gas, hydrogen gas, helium gas, argon gas, etc. The chlorine-based gas may be added alone or in combination with two or more gases selected from oxygen gas, hydrogen gas, helium gas, argon gas, etc. The use of dry etching allows the thin film thickness regions of the mask layer 118R, the mask layer 118G, and the mask layer 118B to be formed with good in-plane uniformity.

[0423] The dry etching apparatus may be a dry etching apparatus having a high-density plasma source. Examples of the dry etching apparatus having a high-density plasma source include 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.

[0424] Furthermore, when dry etching is performed, by-products produced by the dry etching may be deposited on the upper surface and side surfaces of insulating layer 127a, etc. Therefore, components contained in the etching gas, components contained in insulating film 125f, and components contained in mask layers 118R, 118G, and 118B may be contained in insulating layer 127 after the display device is completed.

[0425] Furthermore, the first etching process is preferably performed by wet etching. Using the wet etching method can reduce damage to the EL layer 113R, the EL layer 113G, and the EL layer 113B compared to using the dry etching method. For example, the wet etching can be performed using an alkaline solution. For example, the wet etching of an aluminum oxide film is preferably performed using TMAH, which is an alkaline solution. In this case, the wet etching can be performed by a paddle method. Note that if the insulating film 125f is formed using the same material as the mask layer 118R, the mask layer 118G, and the mask layer 118B, the above etching process can be performed simultaneously, which is preferable.

[0426] 28A and 28B , in the first etching process, the mask layers 118R, 118G, and 118B are not completely removed, and the etching process is stopped when the film thicknesses of the mask layers 118R, 118G, and 118B are reduced. In this manner, by leaving the mask layers 118R, 118G, and 118B on the EL layers 113R, 113G, and 113B, respectively, it is possible to prevent the EL layers 113R, 113G, and 113B from being damaged in subsequent processes.

[0427] 28A and 28B show a configuration in which the mask layers 118R, 118G, and 118B are thin, but the present invention is not limited to this. For example, depending on the thickness of the insulating film 125f and the thicknesses of the mask layers 118R, 118G, and 118B, the first etching process may be stopped before the insulating film 125f is processed into the insulating layer 125. Specifically, the first etching process may be stopped after only partially thinning the insulating film 125f. Furthermore, if the insulating film 125f is formed using the same material as the mask layers 118R, 118G, and 118B, the boundaries between the insulating film 125f and the mask layers 118R, 118G, and 118B may become unclear. As a result, there are cases where it is not possible to determine whether the insulating layer 125 has been formed or whether the film thicknesses of the mask layers 118R, 118G, and 118B have been reduced.

[0428] 28A and 28B show an example in which the shape of the insulating layer 127a remains unchanged from that of FIGS. 27B1 and 27B2, but the present invention is not limited to this. For example, the end of the insulating layer 127a may droop and cover the end of the insulating layer 125. Furthermore, for example, the end of the insulating layer 127a may contact the upper surfaces of the mask layers 118R, 118G, and 118B. As described above, if the developed insulating layer 127a is not exposed to light, the shape of the insulating layer 127a may be easily changed.

[0429] Subsequently, the entire substrate is exposed to visible light or ultraviolet light, and the insulating layer 127a is preferably irradiated with the energy density of the exposure. ２ Greater than 800 mJ / cm ２ It is preferable that the dose is 0 mJ / cm or less. ２ Greater than 500 mJ / cm ２ It is more preferable to perform the following. By performing such exposure after development, the transparency of the insulating layer 127a can be improved in some cases. Furthermore, the substrate temperature required for heat treatment to transform the insulating layer 127a into a tapered shape in a later step can be reduced in some cases.

[0430] On the other hand, as will be described later, not exposing the insulating layer 127a to light may make it easier to change the shape of the insulating layer 127a or to deform the insulating layer 127 into a tapered shape in a later step. Therefore, it may be preferable not to expose the insulating layer 127a to light after development.

[0431] For example, if a photocurable resin is used as the material for the insulating layer 127a, exposing the insulating layer 127a to light initiates polymerization, thereby hardening the insulating layer 127a. At this stage, the insulating layer 127a may not be exposed to light, and at least one of the post-baking and the second etching process described below may be performed while the insulating layer 127a remains in a relatively shape-deformable state. This prevents the formation of irregularities on the surface on which the common layer 114 and the common electrode 115 are formed and also prevents the common layer 114 and the common electrode 115 from being broken apart. Exposure may be performed after development and before the first etching process. However, depending on the material of the insulating layer 127a (e.g., a positive-tone material) and the conditions of the first etching process, exposure may cause the insulating layer 127a to dissolve in the chemical solution during the first etching process. For this reason, it is preferable to perform exposure after the first etching process and before the post-baking process. This allows the insulating layer 127a to be formed in a desired shape with high reproducibility and stability.

[0432] Here, the irradiation of visible light or ultraviolet light is preferably performed in an atmosphere that does not contain oxygen or an atmosphere that contains a low amount of oxygen. For example, the irradiation of visible light or ultraviolet light is preferably performed in an inert gas atmosphere such as a nitrogen atmosphere or a reduced-pressure atmosphere. If the irradiation of visible light or ultraviolet light is performed in an atmosphere that contains a large amount of oxygen, the compounds contained in the EL layer 113 may be oxidized and deteriorated. However, by performing the irradiation of visible light or ultraviolet light in an atmosphere that does not contain oxygen or an atmosphere that contains a low amount of oxygen, the deterioration of the EL layer can be suppressed, and therefore a display device with higher reliability can be provided.

[0433] Next, as shown in FIGS. 29A and 29B , heat treatment (also referred to as post-baking) is performed. As shown in FIGS. 29A and 29B , heat treatment can transform the insulating layer 127a into an insulating layer 127 having tapered side surfaces. As described above, the shape of the insulating layer 127a may already change and have tapered side surfaces when the first etching treatment is completed. The heat treatment is performed at a temperature lower than the heat resistance temperature of the EL layer 113. The heat treatment can be performed at a substrate temperature of 50° C. to 200° C., preferably 60° C. to 150° C., and more preferably 70° C. to 130° C. The heating atmosphere may be an air atmosphere or an inert gas atmosphere. The heating atmosphere may be an atmospheric pressure atmosphere or a reduced-pressure atmosphere. A reduced-pressure atmosphere is preferable because drying can be performed at a lower temperature. The substrate temperature in this heat treatment is preferably higher than that in the heat treatment (pre-bake) performed after the formation of the insulating film 127f. This improves the adhesion between insulating layer 127 and insulating layer 125, and also improves the corrosion resistance of insulating layer 127. Fig. 29B is an enlarged view of EL layer 113G and the end of insulating layer 127 and its vicinity shown in Fig. 29A.

[0434] As described above, in the display device of one embodiment of the present invention, a material with high heat resistance is used for the light-emitting element. Therefore, the pre-baking temperature and the post-baking temperature can be set to 100° C. or higher, 120° C. or higher, or 140° C. or higher, respectively. This can further improve the adhesion between the insulating layer 127 and the insulating layer 125 and the corrosion resistance of the insulating layer 127. Furthermore, the range of materials that can be used for the insulating layer 127 can be broadened. Furthermore, for example, by sufficiently removing the solvent contained in the insulating layer 127, impurities such as water and oxygen can be prevented from entering the EL layer 113.

[0435] By not completely removing the mask layers 118R, 118G, and 118B in the first etching process and leaving the mask layers 118R, 118G, and 118B in a thinner state, it is possible to prevent the EL layers 113R, 113G, and 113B from being damaged and deteriorated during, for example, post-baking, thereby improving the reliability of the light-emitting element.

[0436] 7A and 7B, depending on the material of the insulating layer 127 and the temperature, time, and atmosphere of the post-baking, a concave curved shape may be formed on the side surface of the insulating layer 127. For example, the higher the temperature or the longer the post-baking time, the more likely the shape of the insulating layer 127 is to change, and a concave curved shape may be formed. Furthermore, as described above, if the developed insulating layer 127a is not exposed to light, the shape of the insulating layer 127 may be more likely to change during post-baking.

[0437] Next, as shown in Figures 30A and 30B, an etching process is performed using the insulating layer 127 as a mask to remove portions of the mask layer 118R, the mask layer 118G, and the mask layer 118B. Note that a portion of the insulating layer 125 may also be removed. This forms openings in the mask layer 118R, the mask layer 118G, and the mask layer 118B, respectively, exposing the upper surfaces of the EL layer 113R, the EL layer 113G, the EL layer 113B, and the conductive layer 112C. Note that Figure 30B is an enlarged view of the EL layer 113G and the end of the insulating layer 127 and their vicinity shown in Figure 30A. Note that hereinafter, the etching process using the insulating layer 127 as a mask may be referred to as the second etching process.

[0438] The end of insulating layer 125 is covered with insulating layer 127. Also, Figures 30A and 30B show an example in which part of the end of mask layer 118G, specifically the tapered portion formed by the first etching process, is covered with insulating layer 127, and the tapered portion formed by the second etching process is exposed. In other words, this corresponds to the structure shown in Figures 5A and 5B.

[0439] If the first etching process is not performed and the insulating layer 125 and the mask layer are etched together after post-baking, side etching may cause the insulating layer 125 and the mask layer below the edge of the insulating layer 127 to disappear, forming a cavity. Such a cavity may cause unevenness on the surface on which the common layer 114 and the common electrode 115 are formed, making the common layer 114 and the common electrode 115 more likely to be discontinuous. Even if the insulating layer 125 and the mask layer are side-etched in the first etching process, post-baking can subsequently fill the cavity with the insulating layer 127. The second etching process then etches the thinner mask layer, reducing the amount of side etching and making it less likely for a cavity to form. Even if a cavity does form, it can be extremely small. This allows the surface on which the common layer 114 and the common electrode 115 are formed to be more flat.

[0440] 6A and 6B, or 8A and 8B, the insulating layer 127 may cover the entire edge of the mask layer 118G. For example, the edge of the insulating layer 127 may droop and cover the edge of the mask layer 118G. Furthermore, for example, the edge of the insulating layer 127 may contact the top surface of at least one of the EL layers 113R, 113G, and 113B. As described above, if the developed insulating layer 127a is not exposed to light, the shape of the insulating layer 127 may be easily deformed.

[0441] The second etching process is performed by wet etching. By using wet etching, damage to the EL layers 113R, 113G, and 113B can be reduced compared to when dry etching is used. Wet etching can be performed using an alkaline solution such as TMAH.

[0442] On the other hand, when the second etching process is performed using a wet etching method, if gaps are present between the EL layer 113 and the mask layer 118, between the EL layer 113 and the insulating layer 125, and between the EL layer 113 and the insulating layer 105, for example, due to adhesion issues between the EL layer 113 and other layers, the chemical solution used in the second etching process may penetrate into these gaps and come into contact with the pixel electrodes. If the chemical solution comes into contact with both the conductive layer 111 and the conductive layer 112, the conductive layer with the lower natural potential may corrode due to galvanic corrosion. For example, if aluminum is used as the conductive layer 111 and indium tin oxide is used as the conductive layer 112, the conductive layer 112 may corrode. This may reduce the yield of the display device. Furthermore, the reliability of the display device may be reduced.

[0443] In the manufacturing method of the display device of one embodiment of the present invention, as described above, the conductive layer 112 is formed to cover the top surface and side surfaces of the conductive layer 111. This prevents a chemical solution from contacting the conductive layer 111 in the second etching process, even if there is a gap between the EL layer 113 and the mask layer 118, between the EL layer 113 and the insulating layer 125, or between the EL layer 113 and the insulating layer 105. This prevents corrosion of the pixel electrode, for example, the conductive layer 112. Therefore, the manufacturing method of the display device of one embodiment of the present invention can be a manufacturing method with a high yield. Furthermore, the manufacturing method of the display device of one embodiment of the present invention can prevent defects.

[0444] As described above, by providing the insulating layer 127, the insulating layer 125, the mask layer 118R, the mask layer 118G, and the mask layer 118B, it is possible to prevent poor connection between the light-emitting elements in the common layer 114 and the common electrode 115 due to separation and to prevent an increase in electrical resistance due to a locally thin portion of the film thickness. As a result, the display device of one embodiment of the present invention can have improved display quality.

[0445] Furthermore, after portions of the EL layer 113R, the EL layer 113G, and the EL layer 113B are exposed, further heat treatment may be performed. This heat treatment can remove water contained in the EL layer 113 and water adsorbed to the surface of the EL layer 113. Furthermore, this heat treatment may change the shape of the insulating layer 127. Specifically, the insulating layer 127 may expand to cover at least one of the ends of the insulating layer 125, the ends of the mask layers 118R, 118G, and 118B, and the top surfaces of the EL layers 113R, 113G, and 113B. For example, the insulating layer 127 may have the shape shown in FIGS. 6A and 6B. For example, heat treatment can be performed in an inert gas atmosphere or a reduced-pressure atmosphere. The heat treatment can be performed at a substrate temperature of 50° C. to 200° C., preferably 60° C. to 150° C., more preferably 70° C. to 120° C. A reduced pressure atmosphere is preferable because dehydration can be performed at a lower temperature. However, it is preferable to appropriately set the temperature range of the heat treatment in consideration of the heat resistance temperature of the EL layer 113. Note that, in consideration of the heat resistance temperature of the EL layer 113, a temperature of 70° C. or higher and 120° C. or lower is particularly preferable within the above temperature range.

[0446] 31A , a common layer 114 is formed on the EL layer 113R, the EL layer 113G, the EL layer 113B, the conductive layer 112C, and the insulating layer 127. The common layer 114 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.

[0447] 31A , a common electrode 115 is formed on the common layer 114. The common electrode 115 can be formed by a method such as sputtering or vacuum deposition. Alternatively, the common electrode 115 may be formed by stacking a film formed by deposition and a film formed by sputtering.

[0448] The common electrode 115 can be formed continuously after the common layer 114 is formed, without any intervening process such as etching. For example, after forming the common layer 114 in a vacuum, the common electrode 115 can be formed in a vacuum without removing the substrate into the atmosphere. In other words, the common layer 114 and the common electrode 115 can be formed in a vacuum. This allows the lower surface of the common electrode 115 to be cleaner than when the display device 100 does not include the common layer 114. Therefore, the light-emitting element 130 can be a light-emitting element with high reliability and excellent characteristics.

[0449] 31B, a protective layer 131 is formed on the common electrode 115. The protective layer 131 can be formed by a method such as a vacuum deposition method, a sputtering method, a CVD method, or an ALD method.

[0450] Next, the substrate 120 is attached to the protective layer 131 using the resin layer 122, whereby a display device having the structure shown in Fig. 2A and the structure shown in Fig. 18A can be manufactured. As described above, in the method for manufacturing a display device of one embodiment of the present invention, the conductive layer 112 is formed so as to cover the top surface and the side surface of the conductive layer 111, which can increase yield and suppress occurrence of defects.

[0451] Here, the insulating layer 127 may be exposed after the post-baking shown in FIGS. 29A and 29B is performed to form the insulating layer 127. For example, the insulating layer 127 may be exposed when the above-described exposure is not performed on the insulating layer 127a. For example, the insulating layer 127 may be exposed after the second etching process shown in FIGS. 30A and 30B and before the formation of the common layer 114 shown in FIG. 31A. Alternatively, the insulating layer 127 may be exposed after the formation of the common electrode 115 shown in FIG. 31A and before the formation of the protective layer 131 shown in FIG. 31B. Alternatively, the insulating layer 127 may be exposed after the formation of the protective layer 131 shown in FIG. 31B. Here, for example, the same conditions as those applicable to the exposure of the insulating layer 127a described above may be applied as the conditions for the exposure of the insulating layer 127. Note that the exposure of the insulating layer 127a and the exposure of the insulating layer 127 may not be performed once, may be performed only once in total, or may be performed twice or more in total.

[0452] For example, when a photocurable resin is used for the insulating layer 127, the insulating layer 127 can be cured by exposing the insulating layer 127 to light. This can prevent the insulating layer 127 from being deformed. Therefore, for example, peeling of a layer on the insulating layer 127 can be prevented. As described above, the display device of one embodiment of the present invention can be a highly reliable display device.

[0453] As described above, in the manufacturing method of a display device according to one embodiment of the present invention, the island-shaped EL layers 113R, 113G, and 113B are formed by forming films over the entire surface and then processing them, rather than using a fine metal mask. This allows the island-shaped layers to be formed with uniform thicknesses. This makes it possible to realize a high-resolution display device or a display device with a high aperture ratio. Furthermore, even when the resolution or aperture ratio is high and the distance between subpixels is extremely short, the EL layers 113R, 113G, and 113B can be prevented from contacting each other in adjacent subpixels. Therefore, lateral leakage current between subpixels can be suppressed. This suppresses crosstalk due to unintended light emission, thereby realizing a display device with extremely high contrast.

[0454] Furthermore, by providing the insulating layer 127 having a tapered edge between adjacent island-shaped EL layers 113, it is possible to prevent a step from being generated during the formation of the common electrode 115 and to prevent a locally thin portion from being formed in the common electrode 115. This can prevent a connection failure caused by a disconnected portion in the common layer 114 and the common electrode 115 and an increase in electrical resistance caused by a locally thin portion in the common layer 114 and the common electrode 115. Therefore, the display device of one embodiment of the present invention can achieve both high resolution and high display quality.

[0455] [Manufacturing Method Example 2] Hereinafter, examples of manufacturing methods of the display device 100 having the structure shown in Fig. 10 and the structure shown in Fig. 18C will be described with reference to the drawings. Note that methods different from the methods described in Fig. 24A to Fig. 31B will be mainly described, and methods identical to the methods described in Fig. 24A to Fig. 31B will be omitted as appropriate.

[0456] 32A to 32C show steps similar to those shown in FIGS. 24A to 24C.

[0457] Fig. 32D1 is an enlarged view of the cross section taken along line B1-B2 of Fig. 32C. In the example shown in Fig. 32D1, conductive film 112f has a region overlapping with conductive layer 109.

[0458] 32D2 is a modification of FIG. 32D1 and illustrates an example in which the conductive film 112f does not overlap with the conductive layer 109. For example, after forming the conductive film 112f as shown in FIG. 32C, a portion of the conductive film 112f is removed in the region between B1 and B2, thereby fabricating the configuration shown in FIG. 32D2. When the process shown in FIG. 32D2 is performed, the structure between B1 and B2 of the fabricated display device 100 will be, for example, the structure shown in FIG. 18A.

[0459] For example, by removing the conductive film 112f provided in the region overlapping with the conductive layer 109, the conductive layer 112C formed in a later step will not overlap with the conductive layer 109. Therefore, as described above, for example, the occurrence of parasitic capacitance can be suppressed. Note that the conductive layer 112C may be formed by the step shown in FIG. 32D2. That is, in FIG. 32D2, the conductive film 112f may be replaced with the conductive layer 112C.

[0460] Below, an example of a method for manufacturing the display device 100 will be described assuming that the process shown in Figure 32D2 is not performed, but even if the process shown in Figure 32D2 is performed, the description of the example of the manufacturing method below can be referred to.

[0461] Subsequently, as described above, it is preferable to perform a hydrophobic treatment on the conductive film 112f.

[0462] 33A, an EL film 113Rf, which will later become the EL layer 113R, is formed on the conductive film 112f by the same method as that shown in Fig. 25A. Thereafter, a mask film 118Rf, which will later become the mask layer 118R, and a mask film 119Rf, which will later become the mask layer 119R, are formed in this order on the EL film 113Rf and the conductive film 112f by the same method as that shown in Fig. 25A.

[0463] 33A, a resist mask 190R is formed on the mask film 119Rf by the same method as that shown in Fig. 25A. The resist mask 190R is provided at a position overlapping with the conductive layer 111R. The resist mask 190R can also be provided at a position overlapping with the conductive layer 111C.

[0464] 33A and 33B, a portion of the mask film 119Rf is removed using the resist mask 190R by a method similar to that shown in FIGS. 25A and 25B, to form a mask layer 119R. The mask layer 119R remains on the conductive layer 111R and the conductive layer 111C. Thereafter, the resist mask 190R is removed by a method similar to that shown in FIGS. 25A and 25B. Then, a portion of the mask film 118Rf is removed using the mask layer 119R as a mask by a method similar to that shown in FIGS. 25A and 25B, to form a mask layer 118R.

[0465] Next, as shown in Figures 33A and 33B, the EL film 113Rf is processed by a method similar to that shown in Figures 25A and 25B to form the EL layer 113R. For example, using mask layers 119R and 118R as masks, a portion of the EL film 113Rf is removed to form the EL layer 113R. As a result, as shown in Figure 33B, a layered structure of the EL layer 113R, mask layer 118R, and mask layer 119R remains on the conductive film 112f so as to have an area overlapping with the conductive layer 111R. Furthermore, the conductive film 112f is exposed in areas where the mask layer 119R is not provided.

[0466] The resist mask 190R is preferably provided between B1 and B2 so as to cover from the end of the EL layer 113R to the end of the conductive layer 111C on the EL layer 113R side. As shown in FIG. 33B , the mask layer 118R and the mask layer 119R are provided between B1 and B2 so as to cover from the end of the EL layer 113R to the end of the conductive layer 111C on the EL layer 113R side. This prevents, for example, the conductive film 112f from being exposed between B1 and B2. This prevents portions of the conductive film 112f, the insulating layer 105, the insulating layer 104, and the insulating layer 103 from being removed by etching or the like, thereby preventing the conductive layer 109 from being exposed. This prevents the conductive layer 109 from being unintentionally electrically connected to other conductive layers. For example, this prevents a short circuit between the conductive layer 109 and the common electrode 115 formed in a later process.

[0467] Next, it is preferable to perform, for example, a hydrophobic treatment on the conductive film 112f. During processing of the EL film 113Rf, for example, the surface state of the conductive film 112f may change to a hydrophilic state. For example, by performing the hydrophobic treatment on the conductive film 112f, it is possible to increase the adhesion between the conductive film 112f and a layer (here, the EL layer 113G) formed in a later process, and to suppress film peeling. Note that the hydrophobic treatment is not necessarily required.

[0468] Subsequently, as shown in FIG. 33C, an EL film 113Gf, which will later become the EL layer 113G, is formed on the conductive film 112f and the mask layer 119R by the same method as that shown in FIG. 25C.

[0469] 33C, a mask film 118Gf, which will later become the mask layer 118G, and a mask film 119Gf, which will later become the mask layer 119G, are formed in this order on the EL film 113Gf and the mask layer 119R by the same method as that shown in FIG. 25C. Then, a resist mask 190G is formed.

[0470] The resist mask 190G is provided in a position overlapping with the conductive layer 111G.

[0471] Next, as shown in FIGS. 33C and 33D , a portion of the mask film 119Gf is removed using a resist mask 190G by a method similar to that shown in FIGS. 25C and 25D , forming a mask layer 119G. The mask layer 119G remains on the conductive layer 111G. The resist mask 190G is then removed by a method similar to that shown in FIGS. 25C and 25D . Next, a portion of the mask film 118Gf is removed using the mask layer 119G as a mask, forming a mask layer 118G, by a method similar to that shown in FIGS. 25C and 25D . Next, the EL film 113Gf is processed by a method similar to that shown in FIGS. 25C and 25D , forming an EL layer 113G. For example, a portion of the EL film 113Gf is removed using the mask layer 119G and the mask layer 118G as masks, forming the EL layer 113G.

[0472] 33D , a stacked structure of the EL layer 113G, the mask layer 118G, and the mask layer 119G remains on the conductive layer 111G. In addition, the mask layer 119R is exposed, and the conductive film 112f is exposed in a region where neither the mask layer 119R nor the mask layer 119G is provided.

[0473] Next, it is preferable to perform, for example, hydrophobic treatment on the conductive film 112f. During processing of the EL film 113Gf, for example, the surface state of the conductive film 112f may change to hydrophilic. For example, by performing hydrophobic treatment on the conductive film 112f, for example, adhesion between the conductive film 112f and a layer (here, the EL layer 113B) formed in a later process can be improved, and film peeling can be suppressed. Note that the hydrophobic treatment is not necessarily required.

[0474] Subsequently, as shown in FIG. 34A, an EL film 113Bf, which will later become the EL layer 113B, is formed on the conductive film 112f, the mask layer 119R, and the mask layer 119G by the same method as that shown in FIG. 26A.

[0475] 34A, a mask film 118Bf, which will later become the mask layer 118B, and a mask film 119Bf, which will later become the mask layer 119B, are formed in this order on the EL film 113Bf and the mask layer 119R by the same method as that shown in Fig. 26A. Then, a resist mask 190B is formed.

[0476] The resist mask 190B is provided in a position overlapping with the conductive layer 111B.

[0477] Next, as shown in FIGS. 34A and 34B , a resist mask 190B is used to remove a portion of the mask film 119Bf to form a mask layer 119B. The mask layer 119B remains on the conductive layer 111B. The resist mask 190B is then removed. Next, using the mask layer 119B as a mask, a portion of the mask film 118Bf is removed to form a mask layer 118B. Next, the EL film 113Bf is processed to form the EL layer 113B. For example, using the mask layer 119B and the mask layer 118B as masks, a portion of the EL film 113Bf is removed to form the EL layer 113B.

[0478] 34B , a stacked structure of the EL layer 113B, the mask layer 118B, and the mask layer 119B remains on the conductive layer 111B. The mask layers 119R and 119G are exposed, and the conductive film 112f is exposed in regions where none of the mask layers 119R, 119G, and 119B is provided.

[0479] Next, as shown in FIGS. 34B and 34C , using the mask layers 119R, 119G, and 119B as masks, a portion of the conductive film 112f is removed by, for example, etching. This forms conductive layers 112R, 112G, 112B, and 112C. When a conductive oxide is used as the conductive film 112f, the conductive film 112f can be removed by, for example, wet etching. The conductive layer 112 is formed to cover the top and side surfaces of the conductive layer 111. Note that, for example, when the conductive layer 112 has the configuration shown in FIG. 2B2 , and the conductive layer 112a is made of a metal material and the conductive layer 112b is made of a conductive oxide, a portion of the conductive film that will become the conductive layer 112b can be removed by wet etching, and then a portion of the conductive film that will become the conductive layer 112a can be removed by dry etching.

[0480] Subsequently, as shown in FIG. 35A, the mask layers 119R, 119G, and 119B are preferably removed by a method similar to that shown in FIG. 26C.

[0481] Next, as shown in FIG. 35B, an insulating film 125f, which will later become insulating layer 125, is formed by a method similar to that shown in FIG. 26D so as to cover conductive layer 112R, conductive layer 112G, conductive layer 112B, EL layer 113R, EL layer 113G, EL layer 113B, mask layer 118R, mask layer 118G, and mask layer 118B.

[0482] Figures 35C, 36A to 36D, 37A, and 37B show steps similar to those of Figures 27A, 27B1, 28A, 29A, 30A, 31A, and 31B, respectively. After the step shown in Figure 37B, the substrate 120 is bonded onto the protective layer 131 using the resin layer 122, thereby manufacturing a display device having the structure shown in Figure 10 and the structure shown in Figure 18C.

[0483] [Manufacturing Method Example 3] Hereinafter, examples of manufacturing methods of the display device 100 having the structure shown in Fig. 14 and the structure shown in Fig. 18E will be described with reference to the drawings. Note that methods different from the methods described in Fig. 24A to Fig. 31B will be mainly described, and methods identical to the methods described in Fig. 24A to Fig. 31B will be omitted as appropriate.

[0484] First, the same processes as those shown in Figures 24A to 24D are performed. Next, as shown in Figure 38A, an EL film 113Rf, which will later become the EL layer 113R, is formed on the conductive layer 112R, the conductive layer 112G, the conductive layer 112B, and the insulating layer 105 by a method similar to that shown in Figure 25A. The EL film 113Rf includes a film 113R1f, which will later become the light-emitting unit 113R1, a charge-generating film 113R2f, which will later become the charge-generating layer 113R2, and a film 113R3f, which will later become the light-emitting unit 113R3. In Figure 38A, the charge-generating film 113Rf2 is indicated by a dashed line.

[0485] 38A, a mask film 118Rf which will later become the mask layer 118R and a mask film 119Rf which will later become the mask layer 119R are formed in this order by the same method as that shown in Fig. 25A on the EL film 113Rf, the conductive layer 112C, and the insulating layer 105. Then, as shown in Fig. 38A, a resist mask 190R is formed on the mask film 119Rf by the same method as that shown in Fig. 25A.

[0486] 38A and 38B, a portion of the mask film 119Rf is removed using a resist mask 190R by a method similar to that shown in FIGS. 25A and 25B, to form a mask layer 119R. The mask layer 119R remains on the conductive layer 111R and the conductive layer 111C. Thereafter, the resist mask 190R is removed by a method similar to that shown in FIGS. 25A and 25B. Then, a portion of the mask film 118Rf is removed using the mask layer 119R as a mask by a method similar to that shown in FIGS. 25A and 25B, to form a mask layer 118R.

[0487] Next, as shown in Figures 38A and 38B, the EL film 113Rf is processed using a method similar to that shown in Figures 25A and 25B to form the EL layer 113R. For example, using mask layers 119R and 118R as masks, a portion of the EL film 113Rf is removed to form the EL layer 113R. As described above, the EL layer 113R includes a light-emitting unit 113R1, a charge-generating layer 113R2 on the light-emitting unit 113R1, and a light-emitting unit 113R3 on the charge-generating layer 113R2. The charge-generating layer 113R2 is indicated by a dashed line.

[0488] Next, for example, by performing hydrophobic treatment on the conductive layer 112G, the adhesion between the conductive layer 112G and a layer (here, the EL layer 113G) formed in a later step can be increased, as described above, and film peeling can be suppressed, which is preferable. Note that the hydrophobic treatment is not necessarily required.

[0489] 38C, an EL film 113Gf, which will later become the EL layer 113G, is formed on the conductive layer 112G, the conductive layer 112B, the mask layer 119R, and the insulating layer 105 by a method similar to that shown in FIG. 25C. The EL film 113Gf includes a film 113G1f, which will later become the light-emitting unit 113G1, a charge-generating film 113G2f, which will later become the charge-generating layer 113G2, and a film 113G3f, which will later become the light-emitting unit 113G3. In FIG. 38C, the charge-generating film 113Gf2 is indicated by a dashed line.

[0490] 38C, a mask film 118Gf, which will later become the mask layer 118G, and a mask film 119Gf, which will later become the mask layer 119G, are formed in this order on the EL film 113Gf and the mask layer 119R by the same method as shown in FIG. 25C. Thereafter, a resist mask 190G is formed by the same method as shown in FIG.

[0491] Next, as shown in Figures 38C and 38D, a portion of the mask film 119Gf is removed using a resist mask 190G by a method similar to that shown in Figures 25C and 25D, forming a mask layer 119G. Then, the resist mask 190G is removed by a method similar to that shown in Figures 25C and 25D. Next, a portion of the mask film 118Gf is removed using the mask layer 119G as a mask by a method similar to that shown in Figures 25C and 25D, forming a mask layer 118G. Next, the EL film 113Gf is processed by a method similar to that shown in Figures 25C and 25D, forming an EL layer 113G. As described above, the EL layer 113G includes a light-emitting unit 113G1, a charge-generating layer 113G2 on the light-emitting unit 113G1, and a light-emitting unit 113G3 on the charge-generating layer 113G2. The charge-generating layer 113G2 is indicated by a dashed line.

[0492] 39A, an EL film 113Bf, which will later become the EL layer 113B, is formed on the conductive layer 112B, the mask layer 119R, the mask layer 119G, and the insulating layer 105 by a method similar to that shown in FIG. 26A. The EL film 113Bf includes a film 113B1f, which will later become the light-emitting unit 113B1, a charge-generating film 113B2f, which will later become the charge-generating layer 113B2, and a film 113B3f, which will later become the light-emitting unit 113B3. In FIG. 39A, the charge-generating film 113Bf2 is indicated by a dashed line.

[0493] 39A, a mask film 118Bf, which will later become the mask layer 118B, and a mask film 119Bf, which will later become the mask layer 119B, are formed in this order on the EL film 113Bf and the mask layer 119R by the same method as shown in FIG. 26A. Thereafter, a resist mask 190B is formed by the same method as shown in FIG.

[0494] Next, as shown in Figures 39A and 39B, a portion of the mask film 119Bf is removed using a resist mask 190B in a manner similar to that shown in Figures 26A and 26B, forming a mask layer 119B. Then, the resist mask 190B is removed in a manner similar to that shown in Figures 26A and 26B. Next, a portion of the mask film 118Bf is removed using the mask layer 119B as a mask in a manner similar to that shown in Figures 26A and 26B, forming a mask layer 118B. Next, the EL film 113Bf is processed in a manner similar to that shown in Figures 26A and 26B, forming an EL layer 113B. As described above, the EL layer 113B includes a light-emitting unit 113B1, a charge-generating layer 113B2 on the light-emitting unit 113B1, and a light-emitting unit 113B3 on the charge-generating layer 113B2. The charge-generating layer 113B2 is indicated by a dashed line.

[0495] Figures 39C, 39D, 40A to 40C, 41A, 41B, 42A, and 42B show steps similar to those of Figures 26C, 26D, 27A, 27B1, 28A, 29A, 30A, 31A, and 31B. After the step shown in Figure 42B, the substrate 120 is bonded onto the protective layer 131 using the resin layer 122, thereby manufacturing a display device having the structure shown in Figure 14 and the structure shown in Figure 18E.

[0496] [Manufacturing Method Example 4] Hereinafter, examples of manufacturing methods of the display device 100 having the structure shown in Fig. 19A and the structure shown in Fig. 18A will be described with reference to the drawings. Note that methods different from the methods described in Fig. 24A to Fig. 31B will be mainly described, and methods identical to the methods described in Fig. 24A to Fig. 31B will be omitted as appropriate.

[0497] 24A and 24B are performed, whereby conductive layers 111R, 111G, 111B, and 111C are formed on the plug 106 and the insulating layer 105, as shown in FIG.

[0498] 43B, a conductive film 112f1 is formed on the conductive layer 111R, the conductive layer 111G, the conductive layer 111B, the conductive layer 111C, and the insulating layer 105. The conductive film 112f1 can be formed by, for example, a method similar to that of the conductive film 112f shown in FIG. 24C, and can use a material similar to that of the conductive film 112f.

[0499] 43B and 43C, the conductive film 112f1 is processed to form a conductive layer 112B1 that covers the upper surface and side surfaces of the conductive layer 111B. The conductive film 112f1 can be processed by the same method as that used to process the conductive film 112f.

[0500] 43D , a conductive film 112f2 is formed on the conductive layer 111R, the conductive layer 111G, the conductive layer 112B1, the conductive layer 111C, and the insulating layer 105. The conductive film 112f2 can be formed by the same method as the conductive film 112f, and can be formed using the same material as the conductive film 112f.

[0501] 43D and 43E, the conductive film 112f2 is processed to form a conductive layer 112R1 that covers the upper and side surfaces of the conductive layer 111R, and a conductive layer 112B2 on the conductive layer 112B1. Note that in Fig. 43E, the boundary between the conductive layer 112B1 and the conductive layer 112B2 is indicated by a dotted line.

[0502] 44A , a conductive film 112f3 is formed on the conductive layer 112R1, the conductive layer 111G, the conductive layer 112B2, the conductive layer 111C, and the insulating layer 105. The conductive film 112f3 can be formed by the same method as the conductive film 112f, and can be formed using the same material as the conductive film 112f.

[0503] 44A and 44B , the conductive film 112f3 is processed to form a conductive layer 112R2 on the conductive layer 112R1, a conductive layer 112G covering the upper and side surfaces of the conductive layer 111G, a conductive layer 112B3 on the conductive layer 112B2, and a conductive layer 112C covering the upper and side surfaces of the conductive layer 111C. The conductive layers 112R1 and 112R2 constitute the conductive layer 112R, and the conductive layers 112B1, 112B2, and 112B3 constitute the conductive layer 112B. The conductive film 112f3 can be processed in the same manner as the conductive film 112f. 44B, the boundary between conductive layer 112R1 and conductive layer 112R2, the boundary between conductive layer 112B1 and conductive layer 112B2, and the boundary between conductive layer 112B2 and conductive layer 112B3 are indicated by dotted lines. Similar notations are used in the subsequent drawings.

[0504] As a result, the conductive layers 112R, 112G, and 112B can have different thicknesses. Note that, here, the conductive layer 112B is set to have the thickest thickness and the conductive layer 112G is set to have the thinnest thickness among the conductive layers 112R, 112G, and 112B; however, one embodiment of the present invention is not limited thereto, and the thicknesses of the conductive layers 112R, 112G, and 112B can be set as appropriate. For example, the conductive layer 112R may be set to have the thickest thickness and the conductive layer 112B may be set to have the thinnest thickness among the conductive layers 112R, 112G, and 112B.

[0505] Although the thickness of the conductive layer 112C is set to be equal to the thickness of the conductive layer 112G, one embodiment of the present invention is not limited thereto. For example, the thickness of the conductive layer 112C may be thicker than the thickness of the conductive layer 112G. For example, when processing the conductive film 112f3 as well as when processing the conductive film 112f2, a conductive film may be left so as to cover the upper and side surfaces of the conductive layer 111C. In this case, the thickness of the conductive layer 112C may be set to be equal to the thickness of the conductive layer 112R, for example. Furthermore, when processing any of the conductive films 112f1, 112f2, and 112f3, a conductive film may be left so as to cover the upper and side surfaces of the conductive layer 111C. In this case, the thickness of the conductive layer 112C may be set to be equal to the thickness of the conductive layer 112B, for example.

[0506] 44C , an EL film 113f, which will later become the EL layer 113, is formed on the conductive layer 112R, the conductive layer 112G, the conductive layer 112B, and the insulating layer 105. Then, a mask film 118f, which will later become the mask layer 118, and a mask film 119f, which will later become the mask layer 119, are formed in this order on the EL film 113f, the conductive layer 112C, and the insulating layer 105.

[0507] 44C , a resist mask 190 is formed on the mask film 119f. The resist mask 190 is provided at positions overlapping with the conductive layer 112R, the conductive layer 112G, and the conductive layer 112B. The resist mask 190 is preferably also provided at a position overlapping with the conductive layer 112C. Furthermore, as shown in the cross-sectional view between B1 and B2 in FIG. 44C , the resist mask 190 is preferably provided so as to cover from the end of the EL film 113f to the end of the conductive layer 112C on the EL film 113f side.

[0508] 44C and 44D, a resist mask 190 is used to remove a portion of the mask film 119f to form a mask layer 119. The mask layer 119 remains on the conductive layers 112R, 112G, 112B, and 112C. The resist mask 190 is then removed. Next, using the mask layer 119 as a mask, a portion of the mask film 118f is removed to form a mask layer 118.

[0509] 44C and 44D, the EL film 113f is processed to form the EL layer 113. For example, the EL film 113f is partially removed using the mask layers 119 and 118 as masks, thereby forming the EL layer 113.

[0510] 44D , a stacked structure of the EL layer 113, the mask layer 118, and the mask layer 119 remains on the conductive layer 112R, the conductive layer 112G, and the conductive layer 112B, respectively. In addition, between B1 and B2, the mask layer 118 and the mask layer 119 can be provided so as to cover from the end of the EL layer 113 to the end of the conductive layer 112C on the EL layer 113 side.

[0511] 26C to 31B are then performed. Next, colored layers 132R, 132G, and 132B are formed on the protective layer 131. Next, the substrate 120 is bonded onto the colored layer 132 using the resin layer 122, thereby manufacturing a display device having the configuration shown in FIG. 19A and the configuration shown in FIG. 18A.

[0512] 19A can be manufactured by forming and processing the EL film 113f, the mask film 118f, and the mask film 119f once, and there is no need to do this for each color. This simplifies the manufacturing process of the display device 100. This reduces the manufacturing cost of the display device 100, making it possible to make the display device 100 a low-cost display device.

[0513] [Manufacturing Method Example 5] Hereinafter, examples of a manufacturing method of the display device 100 having the structure shown in Fig. 21A and the structure shown in Fig. 18C will be described with reference to the drawings. Note that methods different from the methods described in Fig. 32A to Fig. 32C and Fig. 33A to Fig. 37B will be mainly described, and methods identical to the methods will be omitted as appropriate.

[0514] 32A to 32C are performed. As a result, as shown in Fig. 45A, conductive layers 111R, 111G, 111B, and 111C are formed on the plug 106 and the insulating layer 105. Furthermore, a conductive film 112f is formed on the conductive layers 111R, 111G, 111B, and 111C and the insulating layer 105.

[0515] 45B , an EL film 113f, which will later become the EL layer 113, is formed on the conductive film 112f. Then, a mask film 118f, which will later become the mask layer 118, and a mask film 119f, which will later become the mask layer 119, are formed in this order on the EL film 113f and the conductive film 112f.

[0516] 45B , a resist mask 190 is formed on the mask film 119f. The resist mask 190 is provided at a position overlapping with the conductive layer 111R, the conductive layer 111G, and the conductive layer 111B. The resist mask 190 is also preferably provided at a position overlapping with the conductive layer 111C. Furthermore, as shown in the cross-sectional view between B1 and B2 in FIG. 45B , the resist mask 190 is preferably provided so as to cover from the end of the EL film 113f to the end of the conductive layer 111C on the EL film 113f side.

[0517] 45B and 45C, a resist mask 190 is used to remove a portion of the mask film 119f to form a mask layer 119. The mask layer 119 remains on the conductive layers 111R, 111G, 111B, and 111C. The resist mask 190 is then removed. Next, using the mask layer 119 as a mask, a portion of the mask film 118f is removed to form a mask layer 118.

[0518] 45B and 45C, the EL film 113f is processed to form the EL layer 113. For example, the EL film 113f is partially removed using the mask layers 119 and 118 as masks, thereby forming the EL layer 113.

[0519] 45C , a stacked structure of the EL layer 113, the mask layer 118, and the mask layer 119 remains on each of the conductive layers 111R, 111G, and 111B. In addition, between B1 and B2, the mask layer 118 and the mask layer 119 can be provided so as to cover from the end of the EL layer 113 to the end of the conductive layer 111C on the EL layer 113 side.

[0520] 34C to 37B are then performed. Next, colored layers 132R, 132G, and 132B are formed on the protective layer 131. Next, the substrate 120 is bonded onto the colored layer 132 using the resin layer 122, thereby manufacturing a display device having the configuration shown in FIG. 21A and the configuration shown in FIG. 18C .

[0521] As described above, the display device 100 having the configuration shown in Fig. 21A can be manufactured by forming and processing the EL film 113f, the mask film 118f, and the mask film 119f once, and there is no need to perform the formation and processing for each color. This simplifies the manufacturing process of the display device 100. This reduces the manufacturing cost of the display device 100, making it possible to make the display device 100 a low-cost display device.

[0522] This embodiment mode can be combined with other embodiment modes as appropriate. In addition, in this specification and the like, when a plurality of configuration examples are shown in one embodiment mode, the configuration examples can be combined as appropriate.

[0523] Embodiment 2 In this embodiment, a structural example of a light-emitting element that can be used for a display device of one embodiment of the present invention, specifically a structural example of a light-emitting element with a tandem structure will be described.

[0524] 46A shows a schematic cross-sectional view of the display device 500. The display device 500 has a light-emitting element 550R that emits red light, a light-emitting element 550G that emits green light, and a light-emitting element 550B that emits blue light.

[0525] The light-emitting element 550R has a configuration in which two light-emitting units (light-emitting unit 512R_1 and light-emitting unit 512R_2) are stacked between a pair of electrodes (electrode 501 and electrode 502) via a charge generation layer 531. Similarly, the light-emitting element 550G has a light-emitting unit 512G_1, a charge generation layer 531, and a light-emitting unit 512G_2 between the pair of electrodes, and the light-emitting element 550B has a light-emitting unit 512B_1, a charge generation layer 531, and a light-emitting unit 512B_2 between the pair of electrodes.

[0526] The electrode 501 functions as a pixel electrode and is provided for each light-emitting element, and the electrode 502 functions as a common electrode and is provided in common to a plurality of light-emitting elements.

[0527] 46A , the light-emitting unit 512R_1 includes a layer 521, a layer 522, a light-emitting layer 523R, and a layer 524. The light-emitting unit 512R_2 includes a layer 522, a light-emitting layer 523R, and a layer 524. The light-emitting element 550R includes a layer 525 between the light-emitting unit 512R_2 and the electrode 502. Note that the layer 525 can also be considered as part of the light-emitting unit 512R_2.

[0528] When the electrode 501 functions as an anode and the electrode 502 functions as a cathode, the layer 521 includes, for example, a layer containing a substance with high hole-injection properties (hole-injection layer). The layer 522 includes, for example, one or both of a layer containing a substance with high hole-transport properties (hole-transport layer) and a layer containing a substance with high electron-blocking properties (electron-blocking layer). The layer 524 includes, for example, one or both of a layer containing a substance with high electron-transport properties (electron-transport layer) and a layer containing a substance with high hole-blocking properties (hole-blocking layer). The layer 525 includes, for example, a layer containing a substance with high electron-injection properties (electron-injection layer).

[0529] When electrode 501 functions as a cathode and electrode 502 functions as an anode, for example, layer 521 includes an electron injection layer, layer 522 includes one or both of an electron transport layer and a hole blocking layer, layer 524 includes one or both of a hole transport layer and an electron blocking layer, and layer 525 includes a hole injection layer.

[0530] The layer 522, the light-emitting layer 523R, and the layer 524 may have the same configuration (material, film thickness, etc.) between the light-emitting unit 512R_1 and the light-emitting unit 512R_2, or may have different configurations.

[0531] 46A shows the layer 521 and the layer 522 separately, but the present invention is not limited to this. For example, when the layer 521 has a function of both a hole injection layer and a hole transport layer, or when the layer 521 has a function of both an electron injection layer and an electron transport layer, the layer 522 may be omitted.

[0532] When a light-emitting element having a tandem structure is fabricated, two light-emitting units are stacked via a charge generation layer 531. The charge generation layer 531 has at least a charge generation region. The charge generation layer 531 has a function of injecting electrons into one of the light-emitting unit 512R_1 and the light-emitting unit 512R_2 and injecting holes into the other when a voltage is applied between the electrode 501 and the electrode 502.

[0533] The light-emitting layer 523R of the light-emitting element 550R contains a light-emitting material that emits red light, the light-emitting layer 523G of the light-emitting element 550G contains a light-emitting material that emits green light, and the light-emitting layer 523B of the light-emitting element 550B contains a light-emitting material that emits blue light. Note that the light-emitting elements 550G and 550B have a configuration in which the light-emitting layer 523R of the light-emitting element 550R is replaced with the light-emitting layer 523G or the light-emitting layer 523B, respectively, and the other configurations are similar to those of the light-emitting element 550R.

[0534] Note that layers 521, 522, 524, and 525 may each have the same configuration (material, film thickness, etc.) for light-emitting elements of two or more colors or for all colors, or may have different configurations for light-emitting elements of all colors.

[0535] A configuration in which a plurality of light-emitting units are connected in series via the charge generation layer 531, such as the light-emitting elements 550R, 550G, and 550B, is referred to as a tandem structure in this specification. On the other hand, a configuration in which one light-emitting unit is between a pair of electrodes is referred to as a single structure. The tandem structure may also be referred to as a stack structure. The tandem structure can provide a light-emitting element capable of emitting high-luminance light. Furthermore, the tandem structure can reduce the current required to obtain the same luminance compared to the single structure, thereby improving the reliability of the light-emitting element.

[0536] The display device 500 of one embodiment of the present invention employs a tandem light-emitting element and can be considered to have an SBS structure. Therefore, the display device 500 can have both the advantages of the tandem structure and the SBS structure. Note that the light-emitting element in the display device 500 shown in FIG. 46A has a structure in which two light-emitting units are formed in series, and therefore may be referred to as a two-tier tandem structure. Furthermore, the light-emitting element 550R having the two-tier tandem structure shown in FIG. 46A has a structure in which a second light-emitting unit having a red light-emitting layer is stacked on a first light-emitting unit having a red light-emitting layer. Similarly, the light-emitting element 550G having the two-tier tandem structure shown in FIG. 46A has a structure in which a second light-emitting unit having a green light-emitting layer is stacked on a first light-emitting unit having a green light-emitting layer, and the light-emitting element 550B has a structure in which a second light-emitting unit having a blue light-emitting layer is stacked on a first light-emitting unit having a blue light-emitting layer.

[0537] Figure 46B is a modified example of the display device 500 shown in Figure 46A. The display device 500 shown in Figure 46B is an example in which the layer 525 is shared by a plurality of light-emitting elements, similar to the electrode 502. In this case, the layer 525 can be called a common layer. By providing one or more common layers between a plurality of light-emitting elements in this way, the manufacturing process can be simplified, and therefore, manufacturing costs can be reduced.

[0538] The display device 500 shown in Figure 47A is an example in which three light-emitting units are stacked. In Figure 47A, the light-emitting element 550R has a light-emitting unit 512R_3 stacked on a light-emitting unit 512R_2 with a charge generation layer 531 interposed therebetween. The light-emitting unit 512R_3 has a similar configuration to the light-emitting unit 512R_2. The light-emitting unit 512G_3 included in the light-emitting element 550G and the light-emitting unit 512B_3 included in the light-emitting element 550B are also similar. Note that when a light-emitting element has multiple charge generation layers 531, two or more or all of the multiple charge generation layers 531 may have the same configuration (material, film thickness, etc.), or all may have different configurations.

[0539] FIG. 47B shows an example in which n light-emitting units (n is an integer of 2 or more) are stacked.

[0540] In this way, by increasing the number of stacked light-emitting units, the luminance obtained from the light-emitting element with the same amount of current can be increased in accordance with the number of stacked light-emitting units.Furthermore, by increasing the number of stacked light-emitting units, the current required to obtain the same luminance can be reduced, and therefore the power consumption of the light-emitting element can be reduced in accordance with the number of stacked light-emitting units.

[0541] 46A , 46B , 47A , and 47B , the light-emitting material of the light-emitting layer is not particularly limited. For example, in FIG. 46A , two light-emitting layers 523R included in a light-emitting element 550R can each contain a phosphorescent material, two light-emitting layers 523G included in a light-emitting element 550G can each contain a fluorescent material, and two light-emitting layers 523B included in a light-emitting element 550B can each contain a fluorescent material.

[0542] Alternatively, for example, in FIG. 46A , the two light-emitting layers 523R of the light-emitting element 550R each have a phosphorescent material, the two light-emitting layers 523G of the light-emitting element 550G each have a phosphorescent material, and the two light-emitting layers 523B of the light-emitting element 550B each have a fluorescent material.

[0543] Furthermore, the display device of one embodiment of the present invention may have a structure in which a fluorescent material is used for all the light-emitting layers of the light-emitting element 550R, the light-emitting element 550G, and the light-emitting element 550B, or a structure in which a phosphorescent material is used for all the light-emitting layers of the light-emitting element 550R, the light-emitting element 550G, and the light-emitting element 550B.

[0544] 46A , for example, a configuration in which a phosphorescent material is used for the light-emitting layer 523R of the light-emitting unit 512R_1 and a fluorescent material is used for the light-emitting layer 523R of the light-emitting unit 512R_2, or a configuration in which a fluorescent material is used for the light-emitting layer 523R of the light-emitting unit 512R_1 and a phosphorescent material is used for the light-emitting layer 523R of the light-emitting unit 512R_2, that is, a configuration in which different light-emitting materials are used for the light-emitting layer in the first stage and the light-emitting layer in the second stage, may be applied. Note that although the description here has been made explicitly regarding the light-emitting unit 512R_1 and the light-emitting unit 512R_2, a similar configuration can also be applied to the light-emitting unit 512G_1 and the light-emitting unit 512G_2, and the light-emitting unit 512B_1 and the light-emitting unit 512B_2.

[0545] This embodiment mode can be co...

Claims

1. 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, and a second insulating layer on the first insulating layer. The first light-emitting element includes a first conductive layer, a second conductive layer covering the upper surface and side surfaces of the first conductive layer, a first EL layer on the second conductive layer, and a common electrode on the first EL layer. The second light-emitting element includes a third conductive layer, a fourth conductive layer covering the upper surface and side surfaces of the third conductive layer, a second EL layer on the fourth conductive layer, and the common electrode on the second EL layer. The first insulating layer has a region located above the first EL layer, a region in contact with the side surface of the first EL layer, a region located above the second EL layer, and a region in contact with the side surface of the second EL layer. The common electrode is provided on the second insulating layer. The reflectance of the first conductive layer with respect to visible light is higher than the reflectance of the second conductive layer with respect to visible light. The reflectance of the third conductive layer with respect to visible light is higher than the reflectance of the fourth conductive layer with respect to visible light, a display device.

2. In Claim 1, The first EL layer includes a first functional layer having a region in contact with the second conductive layer, and a first light-emitting layer on the first functional layer. The second EL layer includes a second functional layer having a region in contact with the fourth conductive layer, and a second light-emitting layer on the second functional layer, a display device.

3. In Claim 2, The first functional layer and the second functional layer each have at least one of a hole injection layer or a hole transport layer. The work function of the second conductive layer is greater than the work function of the first conductive layer. The work function of the fourth conductive layer is greater than the work function of the third conductive layer, a display device.

4. In claim 3, the first light-emitting element has a common layer between the first EL layer and the common electrode, the second light-emitting element has the common layer between the second EL layer and the common electrode, the common layer is located between the second insulating layer and the common electrode, the common layer has at least one of an electron injection layer or an electron transport layer, a display device.

5. In claim 2, the first functional layer and the second functional layer have at least one of an electron injection layer or an electron transport layer, the work function of the second conductive layer is smaller than the work function of the first conductive layer, the work function of the fourth conductive layer is smaller than the work function of the third conductive layer, a display device.

6. In claim 5, the first light-emitting element has a common layer between the first EL layer and the common electrode, the second light-emitting element has the common layer between the second EL layer and the common electrode, the common layer is located between the second insulating layer and the common electrode, the common layer has at least one of a hole injection layer or a hole transport layer, a display device.

7. In any one of claims 1 to 6, the second conductive layer and the fourth conductive layer contain an oxide having any one or more selected from indium, tin, zinc, gallium, titanium, aluminum, and silicon, a display device.

8. In any one of claims 1 to 6, in a cross-sectional view, an end portion of the second insulating layer has a tapered shape with a taper angle of less than 90°, the second insulating layer covers at least a part of a side surface of the first insulating layer, a display device.

9. In any one of claims 1 to 6, A display device, wherein an end portion of the first insulating layer has a tapered shape with a taper angle of less than 90° in a cross-sectional view.

10. In any one of claims 1 to 6, the first insulating layer is an inorganic insulating layer, The display device, wherein the second insulating layer is an organic insulating layer.

11. In any one of claims 1 to 6, the first insulating layer comprises aluminum oxide; The display device, wherein the second insulating layer comprises an acrylic resin.

12. A display device according to any one of claims 1 to 6, A display module having at least one of a connector and an integrated circuit.

13. A display module according to claim 12; An electronic device having at least one of a housing, a battery, a camera, a speaker, and a microphone.

14. forming a first conductive layer; forming a second conductive layer covering an upper surface and a side surface of the first conductive layer and having a reflectance to visible light lower than that of the first conductive layer; forming an EL film on the second conductive layer; forming a mask film on the EL film; the EL film and the mask film are processed to form an EL layer on the second conductive layer and a mask layer on the EL layer.

15. In claim 14, A method for manufacturing a display device, comprising the steps of: performing a hydrophobizing treatment on the second conductive layer after the second conductive layer is formed and before the EL film is formed.

16. In claim 15, A method for manufacturing a display device, wherein the hydrophobic treatment is performed by fluorine-modifying the second conductive layer.

17. Form a first conductive layer and a second conductive layer, Form a third conductive layer that covers the upper surface and side surfaces of the first conductive layer and has a lower reflectance to visible light than the first conductive layer, and a fourth conductive layer that covers the upper surface and side surfaces of the second conductive layer and has a lower reflectance to visible light than the second conductive layer, Form a first EL film on the third conductive layer and on the fourth conductive layer, Form a first mask film on the first EL film, Process the first EL film and the first mask film to form a first EL layer on the third conductive layer and a first mask layer on the first EL layer, and expose the fourth conductive layer, Form a second EL film on the first mask layer and on the fourth conductive layer, Form a second mask film on the second EL film, Process the second EL film and the second mask film to form a second EL layer on the fourth conductive layer and a second mask layer on the second EL layer, and expose the first mask layer, Form an insulating film using a photosensitive material on the first mask layer and on the second mask layer, Process the insulating film to form an insulating layer between the first EL layer and the second EL layer, Perform an etching process using the insulating layer as a mask to expose the upper surface of the first EL layer and the upper surface of the second EL layer, A method for manufacturing a display device, wherein a common electrode is formed on the first EL layer, on the second EL layer, and on the insulating layer.

18. In claim 17, A method for manufacturing a display device, wherein after forming the third conductive layer and the fourth conductive layer and before forming the first EL film, a hydrophobic treatment is performed on the third conductive layer and the fourth conductive layer.

19. In claim 18, A method for manufacturing a display device, wherein the hydrophobization treatment is performed by performing fluorine modification on the third conductive layer and the fourth conductive layer.

20. In any one of claims 17 to 19, A method for manufacturing a display device, wherein the etching treatment is performed by wet etching.