Method for manufacturing a 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

[Technical Field] 【0001】 One aspect of the present invention relates to a display device, a display module, and electronic equipment. Another aspect of the present invention relates to a method for manufacturing a display device. 【0002】 It should be noted that one aspect of the present invention is not limited to the above-mentioned technical field. Examples of technical fields of one aspect of the present invention include semiconductor devices, display devices, light-emitting devices, energy storage devices, memory devices, electronic devices, lighting devices, input devices (e.g., touch sensors), input / output devices (e.g., touch panels), methods for driving them, or methods for manufacturing them. [Background technology] 【0003】 In recent years, display devices have been expected to have applications in a variety of uses. For example, large-scale display devices are used in home television systems (also called televisions or television receivers), digital signage, and PID (Public Information Display). Furthermore, development is progressing on mobile information terminals such as smartphones and tablet devices equipped with touch panels. 【0004】 Furthermore, there is a demand for higher resolution display devices. Devices requiring high-resolution display devices, such as those 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, light-emitting devices (also called light-emitting devices) have been developed. Light-emitting devices that utilize the electroluminescence (EL) phenomenon (also called EL elements or organic EL elements) have features such as being easy to make thin and light, being able to respond quickly to input signals, and being able to be driven using a DC constant voltage power supply, and are being applied to display devices. 【0006】 Patent Document 1 discloses a display device for VR using an organic EL element (also called an organic EL device). 【0007】 Furthermore, Non-Patent Document 1 discloses a method for manufacturing organic optoelectronic devices using standard UV photolithography. [Prior art documents] [Patent Documents] 【0008】 [Patent Document 1] International Publication No. 2018 / 087625 [Non-patent literature] 【0009】 [Non-Patent Document 1] B. Lamprecht et al., “Organic optoelectronic device fabrication using standard UV photolithography” phys.stat.sol. (RRL) 2, No. 1, pp. 16-18 (2008) [Overview of the Initiative] [Problems that the invention aims to solve] 【0010】 For example, an organic EL element can have a configuration in which a layer containing an organic compound is sandwiched between a pair of electrodes. However, if the electrodes are a stacked structure of multiple layers having different materials, the electrodes may be altered due to reactions between these multiple layers, for example. This can lead to a decrease in the yield of the display device. 【0011】 Therefore, one aspect of the present invention aims to provide a highly reliable display device. Alternatively, one aspect of the present invention aims to provide a display device having a light-emitting element with high luminous efficiency. Alternatively, one aspect of the present invention aims to provide a low-power display device. Alternatively, one aspect of the present invention aims to provide a display device with high light extraction efficiency. Alternatively, one aspect of the present invention aims to provide a low-cost display device. Alternatively, one aspect of the present invention aims to provide a display device with high display quality. Alternatively, one aspect of the present invention aims to provide a high-definition display device. Alternatively, one aspect of the present invention aims to provide a high-resolution display device. Alternatively, one aspect of the present invention aims to provide a novel display device. 【0012】 Alternatively, one aspect of the present invention aims to provide a method for manufacturing a display device with a high yield. Alternatively, one aspect of the present invention aims to provide a method for manufacturing a highly reliable display device. Alternatively, one aspect of the present invention aims to provide a method for manufacturing a display device having a light-emitting element with high luminous efficiency. Alternatively, one aspect of the present invention aims to provide a method for manufacturing a display device with low power consumption. Alternatively, one aspect of the present invention aims to provide a method for manufacturing a display device with high light extraction efficiency. Alternatively, one aspect of the present invention aims to provide a method for manufacturing a display device with high display quality. Alternatively, one aspect of the present invention aims to provide a method for manufacturing a high-definition display device. Alternatively, one aspect of the present invention aims to provide a method for manufacturing a high-resolution display device. Alternatively, one aspect of the present invention aims to provide a method for manufacturing a novel display device. 【0013】 Furthermore, the description of these problems does not preclude the existence of other problems. One aspect of the present invention does not necessarily have to solve all of these problems. It is possible to extract other problems from the description in the specification, drawings, and claims. [Means for solving the problem] 【0014】 One aspect of the present invention is a display device comprising: 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 and second light-emitting elements; and a second insulating layer on the first insulating layer, wherein the first light-emitting element comprises: a first conductive layer; a second conductive layer covering the upper 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, wherein the second light-emitting element comprises: a third conductive layer; a fourth conductive layer covering the upper and side surfaces of the third conductive layer; a second EL layer on the fourth conductive layer; and a common electrode on the second EL layer, wherein the common electrode is provided on the second insulating layer, the reflectance of the first conductive layer to visible light is higher than that of the second conductive layer, and the reflectance of the third conductive layer to visible light is higher than that of the fourth conductive layer. 【0015】 Alternatively, in the above embodiment, 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 embodiment, the first functional layer and the second functional layer may each 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 that of the first conductive layer, and the work function of the fourth conductive layer may be greater than that of the third conductive layer. 【0017】 Alternatively, in the above aspect, the first light-emitting element has a common layer between the first EL layer and the common electrode, the second light-emitting element has a 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, 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 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 has a common layer between the first EL layer and the common electrode, the second light-emitting element has a 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, 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 indium, tin, zinc, gallium, titanium, aluminum, and silicon. 【0021】 Alternatively, in the above aspect, the first insulating layer has a region in contact with the side surfaces of the first EL layer and the second EL layer, and covers a part of the upper surface of the first EL layer and a part of the upper surface of the second EL layer. In a cross-sectional view, the end portion of the second insulating layer has a tapered shape with a taper angle less than 90°, and the second insulating layer may cover at least a part of the side surface of the first insulating layer. 【0022】 Alternatively, in the above aspect, in a cross-sectional view, the end portion of the first insulating layer may have a tapered shape with a taper angle less than 90°. 【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 embodiment, the first insulating layer may have aluminum oxide, and the second insulating layer may have acrylic resin. 【0025】 A display module having a display device according to one aspect of the present invention and at least one of a connector and an integrated circuit is also an aspect of the present invention. 【0026】 An electronic device comprising a display module according to one aspect of the present invention, and at least one of a housing, battery, camera, speaker, and microphone, is also according to one aspect of the present invention. 【0027】 Alternatively, one aspect of the present invention is a method for manufacturing a display device, comprising: forming a first conductive layer; forming a second conductive layer that covers the upper and side surfaces of the first conductive layer and has a lower reflectivity to visible light than the first conductive layer; forming an EL film on the second conductive layer; forming a mask film on the EL film; and processing the EL film and the mask film to form an EL layer on the second conductive layer and a mask layer on the EL layer. 【0028】 Alternatively, in the above embodiment, the second conductive layer may be subjected to a hydrophobic treatment after the formation of the second conductive layer and before the formation of the EL film. 【0029】 Alternatively, in the above embodiment, hydrophobic treatment may be performed by fluorine modification of the second conductive layer. 【0030】 Alternatively, in one aspect of the present invention, a first conductive layer and a second conductive layer are formed, a third conductive layer covering the upper and side surfaces of the first conductive layer and having a lower reflectivity to visible light than the first conductive layer is formed, a fourth conductive layer covering the upper and side surfaces of the second conductive layer and having a lower reflectivity to visible light than the second conductive layer is formed, a first EL film is formed on the third conductive layer and the fourth conductive layer is formed, a first mask film is formed on the first EL film, the first EL film and the first mask film are processed to form a first EL layer on the third conductive layer and a first mask layer on the first EL layer, and the fourth conductive layer is exposed, and on the first mask layer and the fourth conductive layer This is a method for manufacturing a display device, comprising: forming a second EL film; forming a second mask film on the second EL film; processing the second EL film and the second mask film to form a second EL layer on a fourth conductive layer and a second mask layer on the second EL layer, and exposing the first mask layer; forming an insulating film on the first mask layer and the second mask layer using a photosensitive material; processing the insulating film to form an insulating layer between the first EL layer and the second EL layer; performing an etching process using the insulating layer as a mask to expose the upper surfaces of the first EL layer and the second EL layer; and forming a common electrode on the first EL layer, the second EL layer and the insulating layer. 【0031】 Alternatively, in the above embodiment, the third conductive layer and the fourth conductive layer may be subjected to a hydrophobic treatment after their formation and before the formation of the first EL film. 【0032】 Alternatively, in the above embodiment, hydrophobic treatment may be performed by fluorine modification of the third conductive layer and the fourth conductive layer. 【0033】 Alternatively, in the above embodiment, the etching process may be carried out by wet etching. [Effects of the Invention] 【0034】 According to one aspect of the present invention, a highly reliable display device can be provided. Alternatively, according to one aspect of the present invention, a display device having a light-emitting element with high luminous efficiency can be provided. Alternatively, according to one aspect of the present invention, a low-power consumption display device can be provided. Alternatively, according to one aspect of the present invention, a display device with high light extraction efficiency can be provided. Alternatively, according to one aspect of the present invention, a low-cost display device can be provided. Alternatively, according to one aspect of the present invention, a display device with high display quality can be provided. Alternatively, according to one aspect of the present invention, a high-definition display device can be provided. Alternatively, according to one aspect of the present invention, a high-resolution display device can be provided. Alternatively, according to one aspect of the present invention, a novel display device can be provided. 【0035】 Alternatively, according to one aspect of the present invention, a method for manufacturing a display device with a high yield can be provided. Alternatively, according to one aspect of the present invention, a method for manufacturing a highly reliable display device can be provided. Alternatively, according to one aspect of the present invention, a method for manufacturing a display device having a light-emitting element with high luminous efficiency can be provided. Alternatively, according to one aspect of the present invention, a method for manufacturing a display device with low power consumption can be provided. Alternatively, according to one aspect of the present invention, a method for manufacturing a display device with high light extraction efficiency can be provided. Alternatively, according to one aspect of the present invention, a method for manufacturing a display device with high display quality can be provided. Alternatively, according to one aspect of the present invention, a method for manufacturing a high-definition display device can be provided. Alternatively, according to one aspect of the present invention, a method for manufacturing a high-resolution display device can be provided. Alternatively, according to one aspect of the present invention, a method for manufacturing a novel display device can be provided. 【0036】 Furthermore, the description of these effects does not preclude the existence of other effects. One aspect of the present invention does not necessarily have to possess all of these effects. Other effects can be extracted from the description, drawings, and claims. [Brief explanation of the drawing] 【0037】 Figure 1 is a plan view showing an example of the configuration of a display device. Figure 2A is a cross-sectional view showing an example of the configuration of a display device. Figures 2B1 and 2B2 are cross-sectional views showing an example of the configuration of a pixel electrode. Figures 3A and 3B are cross-sectional views showing examples of pixel electrode configurations. Figures 4A to 4C are cross-sectional views showing examples of pixel electrode configurations. Figures 5A and 5B are cross-sectional views showing examples of the configuration of a display device. Figures 6A and 6B are cross-sectional views showing examples of the configuration of a display device. Figures 7A and 7B are cross-sectional views showing examples of the configuration of a display device. Figures 8A and 8B are cross-sectional views showing examples of the configuration of a display device. Figures 9A and 9B are cross-sectional views showing examples of the configuration of a display device. Figure 10 is a cross-sectional view showing an example of the configuration of a display device. Figures 11A and 11B are cross-sectional views showing examples of the configuration of a display device. Figures 12A and 12B are cross-sectional views showing examples of the configuration of a display device. Figures 13A and 13B are cross-sectional views showing examples of the configuration of a display device. Figure 14 is a cross-sectional view showing an example of the configuration of a display device. Figures 15A and 15B are cross-sectional views showing examples of the configuration of a display device. Figures 16A and 16B are cross-sectional views showing examples of the configuration of a display device. Figures 17A and 17B are cross-sectional views showing examples of the configuration of a display device. Figures 18A to 18F are cross-sectional views showing examples of the configuration of a display device. Figures 19A and 19B are cross-sectional views showing examples of the configuration of a display device. Figures 20A and 20B are cross-sectional views showing examples of the configuration of a display device. Figures 21A and 21B are cross-sectional views showing examples of the configuration of a display device. Figures 22A and 22B are cross-sectional views showing examples of the configuration of a display device. Figure 23 is a cross-sectional view showing an example of the configuration of a display device. Figures 24A to 24D are cross-sectional views showing examples of methods for manufacturing a display device. Figures 25A to 25D are cross-sectional views showing examples of methods for manufacturing a display device. Figures 26A to 26D are cross-sectional views showing examples of methods for manufacturing a display device. Figures 27A, 27B1, and 27B2 are cross-sectional views showing examples of methods for manufacturing a display device. Figures 28A and 28B are cross-sectional views showing examples of methods for manufacturing a display device. Figures 29A and 29B are cross-sectional views showing examples of methods for manufacturing a display device. Figures 30A and 30B are cross-sectional views showing examples of methods for manufacturing a display device. Figures 31A and 31B are cross-sectional views showing examples of methods for manufacturing a display device. Figures 32A, 32B, 32C, 32D1, and 32D2 are cross-sectional views showing examples of methods for manufacturing a display device. Figures 33A to 33D are cross-sectional views showing examples of methods for manufacturing a display device. Figures 34A to 34C are cross-sectional views showing examples of methods for manufacturing a display device. Figures 35A to 35C are cross-sectional views showing examples of methods for manufacturing a display device. Figures 36A to 36D are cross-sectional views showing examples of methods for manufacturing a display device. Figures 37A and 37B are cross-sectional views showing examples of methods for manufacturing a display device. Figures 38A to 38D are cross-sectional views showing examples of methods for manufacturing a display device. Figures 39A to 39D are cross-sectional views showing examples of methods for manufacturing a display device. Figures 40A to 40C are cross-sectional views showing examples of methods for manufacturing a display device. Figures 41A and 41B are cross-sectional views showing examples of methods for manufacturing a display device. Figures 42A and 42B are cross-sectional views showing examples of methods for manufacturing a display device. Figures 43A to 43E are cross-sectional views showing examples of methods for manufacturing a display device. Figures 44A to 44D are cross-sectional views showing examples of methods for manufacturing a display device. Figures 45A to 45C are cross-sectional views showing examples of methods for manufacturing a display device. Figures 46A and 46B are cross-sectional views showing examples of the configuration of a display device. Figures 47A and 47B are cross-sectional views showing examples of the configuration of a display device. Figures 48A to 48G are plan views showing examples of pixel configurations. Figures 49A to 49I are plan views showing examples of pixel configurations. Figures 50A and 50B are perspective views showing examples of the display module configuration. Figures 51A and 51B are cross-sectional views showing examples of the configuration of a display device. Figures 52A and 52B are cross-sectional views showing examples of the configuration of a display device. Figure 53 is a cross-sectional view showing an example of the configuration of a display device. Figure 54 is a cross-sectional view showing an example of the configuration of a display device. Figure 55 is a cross-sectional view showing an example of the configuration of a display device. Figure 56 is a cross-sectional view showing an example of the configuration of a display device. Figure 57 is a cross-sectional view showing an example of the configuration of a display device. Figure 58 is a cross-sectional view showing an example of the configuration of a display device. Figure 59 is a cross-sectional view showing an example of the configuration of a display device. Figure 60 is a cross-sectional view showing an example of the configuration of a display device. Figure 61 is a cross-sectional view showing an example of the configuration of a display device. Figure 62 is a cross-sectional view showing an example of the configuration of a display device. Figure 63 is a cross-sectional view showing an example of the configuration of a display device. Figure 64 is a cross-sectional view showing an example of the configuration of a display device. Figure 65 is a cross-sectional view showing an example of the configuration of a display device. Figure 66 is a cross-sectional view showing an example of the configuration of a display device. Figure 67 is a cross-sectional view showing an example of the configuration of a display device. Figure 68 is a cross-sectional view showing an example of the configuration of a display device. Figure 69 is a perspective view showing an example of a display device configuration. Figure 70A is a cross-sectional view showing an example of the configuration of a display device. Figures 70B1 and 70B2 are cross-sectional views showing an example of the configuration of a transistor. Figure 71 is a cross-sectional view showing an example of the configuration of a display device. Figure 72 is a cross-sectional view showing an example of the configuration of a display device. Figures 73A to 73B3 are cross-sectional views showing examples of the configuration of a display device. Figures 74A to 74B3 are cross-sectional views showing examples of the configuration of a display device. Figures 75A to 75C are cross-sectional views showing examples of the configuration of a display device. Figures 76A to 76F are cross-sectional views showing examples of the configuration of a light-emitting element. Figures 77A to 77C are cross-sectional views showing examples of the configuration of light-emitting elements. Figures 78A to 78D show examples of electronic devices. Figures 79A to 79F show examples of electronic devices. Figures 80A to 80G show examples of electronic devices. [Modes for carrying out the invention] 【0038】 Embodiments will be described in detail with reference to the drawings. However, it will be readily apparent to those skilled in the art that the present invention is not limited to the following description, and that its form and details can be modified in various ways without departing from the spirit and scope of the present invention. Therefore, the present invention shall not be construed as being limited to the contents of the embodiments shown below. 【0039】 In the configuration of the invention described below, the same reference numerals are used in common across different drawings for identical parts or parts having similar functions, and repeated explanations are omitted. Furthermore, when referring to similar functions, the hatch patterns are the same, and reference numerals may not be assigned. 【0040】 Furthermore, the position, size, and scope of each component shown in the drawings may not represent the actual position, size, and scope for the sake of ease of understanding. Therefore, the disclosed invention is not necessarily limited to the position, size, and scope disclosed in the drawings. 【0041】 The terms "film" and "layer" can be interchanged depending on the context or situation. For example, the term "conductive layer" may be changed to "conductive film." Or, for example, the term "insulating film" may be changed to "insulating layer." 【0042】 In this specification, terms such as "above," "below," "upward," or "downward" are used for convenience to explain the positional relationships between components with reference to the drawings. Furthermore, the positional relationships between components change as appropriate depending on the direction in which each component is depicted. Therefore, the terms used are not limited to those explained in this specification and can be appropriately rephrased depending on the situation. For example, the expression "insulating layer located above the conductive layer" can be rephrased as "insulating layer located below the conductive layer" by rotating the orientation of the drawing shown by 180 degrees. 【0043】 In this specification, devices fabricated using a metal mask or an FMM (Fine Metal Mask, a high-resolution metal mask) may be referred to as MM (Metal Mask) structured devices. Furthermore, in this specification, devices fabricated without using a metal mask or FMM may be referred to as MML (Metal Maskless) structured devices. 【0044】 In this specification, holes or electrons may be referred to as "carriers." Specifically, a hole injection layer or electron injection layer may be called a "carrier injection layer," a hole transport layer or electron transport layer may be called a "carrier transport layer," and a hole block layer or electron block layer may be called a "carrier block layer." Note that the above-mentioned carrier injection layer, carrier transport layer, and carrier block layer may not be clearly distinguishable by their cross-sectional shape or characteristics. Furthermore, a single layer may combine the functions of two or three of the carrier injection layer, carrier transport layer, and carrier block layer. 【0045】 In this specification, a light-emitting device has an EL layer between a pair of electrodes. The EL layer has at least an emissive layer. Examples of layers in the EL layer include an emissive layer, a carrier injection layer, a carrier transport layer, and a carrier block layer. 【0046】 In this specification, the carrier injection layer refers to either or both a hole injection layer and an electron injection layer. The carrier transport layer refers to either or both a hole transport layer and an electron transport layer. Furthermore, the carrier block layer refers to either or both 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 where the angle between the inclined side surface and the substrate surface (also called the taper angle) is less than 90°. The side surface of the structure and the substrate surface do not necessarily have to be perfectly flat; they may be substantially planar with a fine curvature, or substantially planar with fine irregularities. 【0048】 (Embodiment 1) This embodiment describes a display device according to one aspect of the present invention and a method for manufacturing the same. 【0049】 A display device according to one aspect of the present invention is capable of full-color display. For example, a display device capable of full-color display can be manufactured by creating separate EL layers, each having at least an emissive layer, for each emissive color. Alternatively, a display device capable of full-color display can be manufactured by providing a colored layer (also called a color filter) on an EL layer that emits white light, for example. 【0050】 A structure in which different light-emitting layers are created or painted using light-emitting elements of each color (for example, blue (B), green (G), and red (R)) is sometimes called an SBS (Side By Side) structure. Furthermore, a light-emitting element capable of emitting white light is sometimes called a white light-emitting element. 【0051】 When manufacturing a display device having multiple light-emitting elements, each with a different emission color, it is necessary to form each light-emitting layer with a different emission color in an island-like configuration. Furthermore, even when manufacturing a display device with a white light-emitting element, forming the light-emitting layers in an island-like configuration is preferable because it can reduce the leakage current that may occur between adjacent light-emitting elements via the light-emitting layers. 【0052】 In this specification, "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 and an adjacent light-emitting layer are physically separated. 【0053】 For example, island-shaped light-emitting layers can be formed using a vacuum deposition method with a metal mask. However, this method is susceptible to various factors, including the precision of the metal mask, misalignment between the metal mask and the substrate, deflection of the metal mask, and the spread of the film's outline due to vapor scattering, which can cause deviations from the design in the shape and position of the island-shaped light-emitting layers. Therefore, it is difficult to achieve high resolution and high aperture ratio in display devices. Furthermore, during deposition, the layer's outline may become blurred, and the thickness at the edges may decrease. In other words, the thickness of the island-shaped light-emitting layers may vary depending on the location. Additionally, when manufacturing large, high-resolution, or high-definition display devices, there are concerns that the low dimensional accuracy of the metal mask and deformation due to heat, etc., may lead to low manufacturing yield. 【0054】 Therefore, when manufacturing a display device according to one aspect 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, after forming a pixel electrode for each sub-pixel, a light-emitting layer is deposited across multiple pixel electrodes. Subsequently, the light-emitting layer is processed using photolithography to form one island-shaped light-emitting layer for each pixel electrode. This divides the light-emitting layer for each sub-pixel, allowing for the formation of an island-shaped light-emitting layer for each sub-pixel. 【0055】 When processing the above-mentioned light-emitting layer into an island shape, a structure in which the processing is performed using photolithography directly above the light-emitting layer is conceivable. In this structure, the light-emitting layer may be damaged, for example, by processing, and its reliability may be significantly impaired. Therefore, when manufacturing a display device according to one aspect of the present invention, it is preferable to use a method in which, in addition to the light-emitting layer as an EL layer, a functional layer located above the light-emitting layer, such as a carrier block layer, carrier transport layer, or carrier injection layer, more specifically a hole block layer, electron transport layer, or electron injection layer, is formed on a mask layer, 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 having a functional layer between the light-emitting layer and the mask layer, exposure of the light-emitting layer to the outermost surface during the manufacturing process of the display device can be suppressed, and damage to the light-emitting layer can be reduced. 【0056】 In this specification, the terms "mask film" and "mask layer" refer to a film and a layer, respectively, that are located above at least the light-emitting layer, or more specifically, above the layer that is processed into an island shape among the layers constituting the EL layer, and that have the function of protecting the light-emitting layer during the manufacturing process. The mask film may also be called a sacrificial film or protective film, and the mask layer may also be called a sacrificial layer or protective layer. 【0057】 The EL layer may have functional layers not only above the light-emitting layer but also below it. When the light-emitting layer is processed into an island shape, it is preferable to process the functional layers located below the light-emitting layer (for example, 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, etc.) into an island shape using the same pattern as the light-emitting layer. By processing the layers located below the light-emitting layer into an island shape using the same pattern as the light-emitting layer, it is possible to reduce the leakage current (sometimes called lateral leakage current, transverse leakage current, or lateral leakage current) that may occur between adjacent subpixels. For example, when a hole injection layer is used in common between adjacent subpixels, a transverse leakage current may occur due to the hole injection layer. On the other hand, in a display device according to one aspect of the present invention, since the hole injection layer can be processed into an island shape using the same pattern as the light-emitting layer, the transverse leakage current between adjacent subpixels is substantially eliminated or can be made extremely small. 【0058】 In this configuration, it is preferable that the EL layer be provided so as to cover the top and side surfaces of the pixel electrodes. This makes it easier to increase the aperture ratio compared to a configuration where the edges of the EL layer are located inside the edges of the pixel electrodes. 【0059】 Furthermore, it is preferable that the pixel electrode has a stacked structure of multiple layers having different materials. For example, if the display device is of the top emission type and the pixel electrode has a two-layer stacked 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. Also, if the functional layer located below the light-emitting layer has, for example, at least one of a hole injection layer or 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 larger 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 larger work function than the first conductive layer. As a result, a light-emitting element can be made that has high light extraction efficiency and a low driving voltage. 【0060】 In this specification, visible light refers to light with a wavelength of 400 nm or more and less than 750 nm. Furthermore, reflectance for visible light refers to the reflectance for light within a predetermined range of wavelengths within the 400 nm to less than 750 nm range. For example, the average or maximum reflectance for all wavelengths of light between 400 nm and less than 750 nm may be used as the reflectance for visible light. Alternatively, the reflectance for a specific wavelength within the 400 nm to less than 750 nm range may be used as the reflectance for visible light. 【0061】 On the other hand, when the pixel electrode is constructed as a stacked structure of multiple layers made of different materials, the pixel electrode may be altered due to reactions between these multiple layers, for example. For example, in a method for manufacturing a display device according to one aspect of the present invention, when a film formed after the formation of the pixel electrode is removed by a wet etching method, the chemical solution may come into contact with the pixel electrode. When the pixel electrode is constructed as a stacked structure of multiple layers, galvanic corrosion may occur when these multiple layers come into contact with the chemical solution. As a result, at least one of the layers constituting the pixel electrode may be altered. Therefore, the yield of the display device may decrease. In addition, the reliability of the display device may decrease. 【0062】 Therefore, in one aspect of the present invention, a second conductive layer is formed so as to cover the upper and side surfaces of the first conductive layer. This makes it possible to suppress contact between the chemical solution and the first conductive layer, even when removing a film formed after the formation of a pixel electrode having the first conductive layer and the second conductive layer by a wet etching method. Thus, for example, the occurrence of galvanic corrosion on the pixel electrode can be suppressed. As a result, the display device according to one aspect of the present invention can be manufactured using a method with a high yield. Furthermore, the display device according to one aspect of the present invention can suppress the occurrence of defects and be a highly reliable display device. 【0063】 Furthermore, in light-emitting elements that emit light of different colors, it is not necessary to fabricate all the layers constituting the EL layer separately; some layers can be formed in the same process. In a method for manufacturing a display device according to one aspect of the present invention, some of the layers constituting the EL layer are formed in island-like structures for each color, then at least a portion of the mask layer is removed, and the remaining layers constituting the EL layer (sometimes called a common layer) and the common electrode (also called an upper electrode) are formed in common for each color, that is, as a single film. For example, the carrier injection layer and the common electrode can be formed in common for each color. 【0064】 On the other hand, the carrier injection layer is often a relatively conductive layer within the EL layer. Therefore, there is a risk of the light-emitting element short-circuiting if the carrier injection layer comes into contact with the side surface of some of the island-shaped EL layers or the side surface of the pixel electrode. Furthermore, 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 the light-emitting element short-circuiting 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, a display device according to one aspect of the present invention has an insulating layer that covers at least the sides of the island-shaped light-emitting layer. Furthermore, it is preferable that the insulating layer covers a portion of the upper surface of the island-shaped light-emitting layer. 【0066】 This prevents at least a portion of the island-shaped EL layer and the pixel electrodes from coming into contact with the carrier injection layer and the common electrode. Therefore, it is possible to suppress short circuits in the light-emitting element and improve the reliability of the light-emitting element. 【0067】 In a cross-sectional view, it is preferable that the edges of the insulating layer have a tapered shape with a taper angle of less than 90°. This suppresses the step break in the common layer and common electrode provided on the insulating layer. Therefore, connection failures due to step breaks can be suppressed. In addition, it is possible to suppress the local thinning of the common electrode due to the step, which would increase electrical resistance. 【0068】 In this specification, "step breakage" refers to a phenomenon in which a layer, film, or electrode is divided due to the shape of the surface to which it is formed, such as a step, or in which a locally thinner film is formed. 【0069】 Thus, the island-shaped light-emitting layer produced by the method for manufacturing a display device according to one aspect of the present invention is not formed using a fine metal mask, but rather by processing after the light-emitting layer has been deposited on one surface. Therefore, it is possible to realize a high-definition display device or a display device with a high aperture ratio, which has been difficult to achieve until now. Furthermore, since the light-emitting layer can be made separately for each color, it is possible to realize a display device that is extremely vivid, has high contrast, and has high display quality. In addition, 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, and the reliability of the light-emitting element can be improved. 【0070】 Furthermore, while it is difficult to reduce the distance between adjacent light-emitting elements to less than 10 μm using, for example, a formation method employing a fine metal mask, according to one embodiment of the present invention, the distance between adjacent light-emitting elements, the distance between adjacent EL layers, or the distance between adjacent pixel electrodes can 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. Moreover, by using, for example, an exposure apparatus for LSIs, the distance between adjacent light-emitting elements, the distance between adjacent EL layers, or the distance between 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 significantly reduces the area of ​​the non-emitting region that may exist between two light-emitting elements, making it possible to bring the aperture ratio closer to 100%. For example, in a display device according to one aspect of the present invention, the aperture ratio can be 40% or more, 50% or more, 60% or more, 70% or more, 80% or more, and even 90% or more, while achieving less than 100%. 【0071】 Furthermore, increasing the aperture ratio of a display device can improve its reliability. More specifically, using an organic EL element, if the lifespan of a display device with an aperture ratio of 10% is used as a baseline, a display device with an aperture ratio of 20%, i.e., twice the baseline, will have a lifespan approximately 3.25 times longer, and a display device with an aperture ratio of 40%, i.e., four times the baseline, will have a lifespan approximately 10.6 times longer. Thus, as the aperture ratio is increased, the current density flowing through the organic EL element can be reduced, making it possible to improve the lifespan of the display device. In one embodiment of the present invention, since the aperture ratio can be increased, the display quality of the display device can be improved. Moreover, as the aperture ratio of the display device is increased, excellent effects such as a significant improvement in the reliability of the display device, especially its lifespan, are achieved. 【0072】 Furthermore, the pattern of the light-emitting layer itself can be made extremely small compared to when a fine metal mask is used. Also, for example, when a metal mask is used to create different types of light-emitting layers, variations in thickness occur between the center and edges of the pattern, so the effective area that can be used as a light-emitting region is small relative to the total area of ​​the pattern. On the other hand, with the above manufacturing method, since a film deposited to a uniform thickness is processed, island-shaped light-emitting layers can be formed with a uniform thickness. Therefore, even with a fine pattern, almost the entire area can be used as a light-emitting region. As a result, it is possible to manufacture a display device that combines high resolution and a high aperture ratio. Furthermore, it is possible to achieve miniaturization and weight reduction of the display device. 【0073】 Specifically, the resolution of the display device according to one embodiment of the present invention is, for example, 2000 ppi or more, preferably 3000 ppi or more, more preferably 5000 ppi or more, and even more preferably 6000 ppi or more, and can be 20000 ppi or less, or 30000 ppi or less. 【0074】 [Configuration Example 1] Figure 1 is a plan view showing an example configuration of the display device 100. The display device 100 has a pixel section 107 in which a plurality of pixels 108 are arranged in a matrix. The pixels 108 include sub-pixels 110R, sub-pixels 110G, and sub-pixels 110B. In Figure 1, a 2x6 sub-pixel 110 is shown, and these constitute a 2x2 pixel 108. 【0075】 In this specification, for example, when describing matters common to sub-pixels 110R, 110G, and 110B, they may be referred to simply as sub-pixel 110. Similarly, when describing matters common to other components distinguished by letters, the letters may be omitted and the corresponding symbols used. 【0076】 Sub-pixel 110R emits red light, sub-pixel 110G emits green light, and sub-pixel 110B emits blue light. This allows an image to be displayed on the pixel unit 107. Therefore, the pixel unit 107 can be called a display unit. In this embodiment, three sub-pixels of red (R), green (G), and blue (B) are used as an example, but three sub-pixels of yellow (Y), cyan (C), and magenta (M) may also be used. Furthermore, the number of sub-pixel types is not limited to three, but 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】 Furthermore, it can be said that a stripe array is applied to pixel 108 shown in Figure 1. Note that the array method that can be applied to pixel 108 is not limited to this; other array methods such as stripe arrays, S-stripe arrays, delta arrays, Bayer arrays, or zigzag arrays may also be applied, as well as pentile arrays or diamond arrays. 【0078】 In this specification and other documents, the row direction is sometimes referred to as the X direction, and the column direction as the Y direction. The X and Y directions intersect, for example, perpendicularly. 【0079】 Figure 1 shows an example where subpixels of different colors are arranged in the X direction and subpixels of the same color are arranged in the Y direction. Alternatively, subpixels of different colors may be arranged in the Y direction and subpixels of the same color may be arranged in the X direction. 【0080】 A region 141 and a connecting portion 140 are provided on the outside of the pixel portion 107, with the region 141 located between the pixel portion 107 and the connecting portion 140. An EL layer 113 is provided in the region 141. A conductive layer 111C is provided in the connecting portion 140. 【0081】 Figure 1 shows an example where, in a plan view, region 141 and connecting portion 140 are located to the right of the pixel portion 107, but the positions of region 141 and connecting portion 140 are not particularly limited. Region 141 and connecting portion 140 only need to be provided in at least one location among the upper, right, left, and lower sides of the pixel portion 107 in a plan view, and may be provided so as to surround all four sides of the pixel portion 107. The upper surface shape of region 141 and connecting portion 140 can be a strip, L-shape, U-shape, or frame shape, etc. Also, there may be one region 141 and multiple connecting portions 140. 【0082】 Figure 2A is a cross-sectional view between the dashed line A1-A2 in Figure 1, and is a cross-sectional view showing an example of the configuration of a pixel 108 provided in the pixel section 107. As shown in Figure 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, insulating layer 104, and insulating layer 103 are provided with openings that reach the conductive layer 102, and plugs 106 are provided to fill these openings. 【0083】 In the pixel section 107, light-emitting elements 130 are provided on the insulating layer 105 and on the plug 106. A protective layer 131 is provided to cover the light-emitting elements 130. The 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】 In Figure 2A, multiple cross-sections of the insulating layer 125 and insulating layer 127 are shown, but in a plan view of the display device 100, the insulating layer 125 and insulating layer 127 are connected as one unit each. In other words, the display device 100 can be configured to have, for example, one insulating layer 125 and one insulating layer 127. The display device 100 may also have multiple insulating layers 125 that are separated from each other, or multiple insulating layers 127 that are separated from each other. 【0085】 In Figure 2A, the light-emitting element 130 is shown as light-emitting element 130R, light-emitting element 130G, and light-emitting element 130B. Light-emitting elements 130R, 130G, and 130B emit light of different colors from each other. 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. In addition, light-emitting elements 130R, 130G, or 130B may emit cyan, magenta, yellow, white, or infrared light. 【0086】 One embodiment of the present invention is a top-emission type display device that emits light in the opposite direction to the substrate on which the light-emitting element is formed. 【0087】 Preferably, the light-emitting element 130 is an OLED (Organic Light Emitting Diode) or a QLED (Quantum-dot Light Emitting Diode). Examples of light-emitting materials for the light-emitting element 130 include fluorescent materials, phosphorescent materials, inorganic compounds (e.g., quantum dot materials), and thermally activated delayed fluorescence (Thermally Activated Delayed Fluorescence (TADF) materials). Alternatively, an LED such as a microLED (Light Emitting Diode) can be used as the light-emitting element 130. 【0088】 The light-emitting element 130R includes a conductive layer 111R on the plug 106 and on the insulating layer 105, a conductive layer 112R covering the top and sides of the conductive layer 111R, an EL layer 113R covering the top and sides 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 constitute the 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 be collectively referred to as the 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 top and sides of the conductive layer 111G, an EL layer 113G covering the top and sides of the conductive layer 112G, a common layer 114 on the EL layer 113G, and a common electrode 115 on the common layer 114. Here, the conductive layer 111G and the conductive layer 112G constitute the 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 the EL layer. 【0090】 The light-emitting element 130B includes a conductive layer 111B on the plug 106 and on the insulating layer 105, a conductive layer 112B covering the top and sides of the conductive layer 111B, an EL layer 113B covering the top and sides 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 constitute the 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 be collectively referred to as the EL layer. 【0091】 Of the pixel electrodes and common electrodes of a light-emitting element, one functions as the anode and the other as the cathode. In the following, unless otherwise specified, it is assumed that the pixel electrodes function as the anode and the common electrodes function as the cathode. 【0092】 EL layer 113R, EL layer 113G, and EL layer 113B each have at least an emissive layer. For example, EL layer 113R may have an emissive layer that emits red light, EL layer 113G may have an emissive layer that emits green light, and EL layer 113B may have an emissive layer that emits blue light. EL layer 113R, EL layer 113G, or EL layer 113B may emit light such as cyan, magenta, yellow, white, or infrared. 【0093】 The EL layers 113R, 113G, and 113B are spaced apart from each other. By providing the EL layers 113 in an island-like arrangement for each light-emitting element 130, leakage current between adjacent light-emitting elements 130 can be suppressed. This suppresses crosstalk caused by unintended light emission, enabling the realization of a display device with extremely high contrast. In particular, it enables the realization of a display device with high current efficiency at low brightness. 【0094】 The island-shaped EL layer 113 can be formed by depositing an EL film and processing the EL film, for example, using photolithography. For example, EL layer 113R can be formed by depositing and processing an EL film that will become EL layer 113R, EL layer 113G can be formed by depositing and processing an EL film that will become EL layer 113G, and EL layer 113B can be formed by depositing and processing an EL film that will become EL layer 113B. 【0095】 The EL layer 113 is provided so as to cover the top and side surfaces of the pixel electrodes of the light-emitting element 130. This makes it easier to increase the aperture ratio of the display device 100 compared to a configuration where the edges of the EL layer 113 are located inward from the edges of the pixel electrodes. In addition, by covering the side surfaces of the pixel electrodes of the light-emitting element 130 with the EL layer 113, contact between the pixel electrodes and the common electrode 115 can be suppressed, thereby suppressing short circuits of 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 electrodes, EL layer 113, and common electrode 115 overlap each other, and the edges of the EL layer 113 can be increased. Since the edges of the EL layer 113 may be damaged during processing, using a region away from the edges of the EL layer 113 as the light-emitting region can sometimes improve the reliability of the light-emitting element 130. 【0096】 Furthermore, in a display device according to one aspect of the present invention, the pixel electrode of the light-emitting element is configured as a stacked structure of multiple layers. For example, in the example shown in Figure 2A, the pixel electrode of the light-emitting element 130 is configured as a stacked structure of a conductive layer 111 and a conductive layer 112. For example, if 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 be a layer with a higher reflectivity for visible light than the conductive layer 112, and the conductive layer 112 can be a layer with a larger work function than the conductive layer 111. The higher the reflectivity for visible light of the pixel electrode, the more effectively it is possible to suppress the transmission of light emitted by the EL layer 113 through the pixel electrode. Therefore, if the display device 100 is a top-emission type, the efficiency of extracting light emitted by the EL layer 113 increases. Also, if the pixel electrode functions as an anode, the larger the work function of the pixel electrode, the easier it is to inject holes into the EL layer 113, thus allowing the driving voltage of the light-emitting element to be lowered. Based on the above, by arranging the pixel electrodes of the light-emitting element 130 in a stacked configuration of a conductive layer 111 with high reflectivity for visible light and a conductive layer 112 with a large work function, the light-emitting element 130 can be made into a light-emitting element with high light extraction efficiency and low driving voltage. 【0097】 When the conductive layer 111 is a layer with a higher reflectivity to visible light than the conductive layer 112, the reflectivity of the conductive layer 111 to visible light is preferably 40% to 100%, and more preferably 70% to 100%. The conductive layer 112 can be an electrode that is transparent to visible light (also called a transparent electrode). 【0098】 In this specification, a transparent electrode refers to an electrode having a transmittance of 40% or more to visible light. 【0099】 Furthermore, the conductive layer 111 of the light-emitting element 130 is a layer with high reflectivity to the light emitted by the EL layer 113. For example, if the EL layer 113 emits infrared light, the conductive layer 111 can be a layer with high reflectivity to infrared light. Also, if the pixel electrode of the light-emitting element 130 functions as a cathode, the conductive layer 112 can be a layer with a smaller work function than the conductive layer 111, for example. 【0100】 On the other hand, when the pixel electrode is constructed in a stacked configuration of multiple layers, the pixel electrode may be altered due to reactions between these layers, for example. For example, as will be described in detail later, when removing a film formed after the pixel electrode is formed by a wet etching method during the fabrication of the display device 100, the chemical solution may come into contact with the pixel electrode. When the pixel electrode is constructed in a stacked configuration of multiple layers, galvanic corrosion may occur when these layers come into contact with the chemical solution. As a result, at least one of the layers constituting the pixel electrode may be altered. Therefore, the yield of the display device may decrease. In addition, the reliability of the display device may decrease. 【0101】 Therefore, in the display device 100, a conductive layer 112 is formed so as to cover the upper and side surfaces of the conductive layer 111. This makes it possible to suppress contact between the chemical solution and the conductive layer 111, even when removing a film formed after the formation of a pixel electrode having the conductive layer 111 and the conductive layer 112 by a wet etching method. Thus, the occurrence of galvanic corrosion on the pixel electrode can be suppressed. As a result, the display device 100 can be manufactured using a method with a high yield. Furthermore, since the occurrence of defects in the display device 100 can be suppressed, the display device 100 can be made into a highly reliable display device. 【0102】 For example, a metallic material can be used as the conductive layer 111. For example, metals such as 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), or neodymium (Nd), or alloys containing these in appropriate combinations can be used. As alloy materials, for example, aluminum-containing alloys such as aluminum, nickel, and lanthanum alloys (Al-Ni-La), as well as silver-containing alloys such as silver-magnesium alloys, or silver-palladium-copper alloys (Ag-Pd-Cu, also written as APC) can be used. 【0103】 As the conductive layer 112, an oxide having one or more selected from indium, tin, zinc, gallium, titanium, aluminum, and silicon can be used. For example, it is preferable to use a conductive oxide containing one or more of the following: 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, silicon-containing indium tin oxide has a large work function, for example, a work function of 4.0 eV or more, so it can be suitably used as the conductive layer 112 when the pixel electrode functions as an anode. 【0104】 As will be described in detail later, the conductive layer 111 may be a laminated structure of multiple layers having different materials, and the conductive layer 112 may be a laminated structure of multiple layers having different materials. In this case, the conductive layer 111 may have a layer made of a material that can be used for the conductive layer 112, such as a conductive oxide. Also, the conductive layer 112 may have a layer made of a material that can be used for the conductive layer 111, such as a metallic material. For example, if the conductive layer 112 has a laminated structure of two or more layers, the layer in contact with the conductive layer 111 may be a layer made of a material that can be used for the conductive layer 111, such as a metallic material. 【0105】 Here, the end of the conductive layer 111 may have a tapered shape. Specifically, it is preferable that the end of the conductive layer 111 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 making the side surface of the conductive layer 112 tapered, the coverage of the EL layer 113 provided along the side surface of the conductive layer 112 can be improved. 【0106】 In Figure 2A, there is no insulating layer (also called a barrier or structure) covering the upper edge of the conductive layer 112R between the conductive layer 112R and the EL layer 113R. Similarly, there is no insulating layer covering the upper edge of the conductive layer 112G between the conductive layer 112G and the EL layer 113G. Furthermore, there is no insulating layer covering the upper edge of the conductive layer 112B between the conductive layer 112B and the EL layer 113B. Therefore, the distance between adjacent light-emitting elements 130 can be made extremely narrow. Consequently, a high-definition or high-resolution display device can be produced. Additionally, a mask for forming the insulating layer becomes unnecessary, reducing the manufacturing cost of the display device. 【0107】 Furthermore, by omitting an insulating layer covering the edges of the conductive layer 112 between the conductive layer 112 and the EL layer 113, light emission from the EL layer 113 can be efficiently extracted. Therefore, the display device 100 can have extremely low viewing angle dependence. By reducing viewing angle dependence, the visibility of images on the display device 100 can be improved. For example, in the display device 100, the viewing angle (the maximum angle at which a constant contrast ratio is maintained when viewing the screen from an oblique direction) can be in the 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 vertical and horizontal viewing angles. 【0108】 Insulating layer 101, insulating layer 103, and insulating layer 105 function as interlayer insulating layers. Various inorganic insulating films such as oxide insulating films, nitride insulating films, oxidative nitride insulating films, or nitride oxide insulating films can be suitably used as insulating layers 101, insulating layer 103, and insulating layer 105. Specifically, for example, silicon oxide film, silicon oxidative nitride film, aluminum oxide film, silicon nitride film, or silicon nitride oxide film can be used. 【0109】 In this specification, "oxide nitride" refers to a material in which the oxygen content is greater than the nitrogen content, and "nitride oxide" refers to a material in which the nitrogen content is greater than the oxygen content. For example, when "silicon oxynitride" is written, it refers to a material in which the oxygen content is greater than the nitrogen content, and when "silicon nitride oxide" is written, it refers to a material in which the nitrogen content is greater than the oxygen content. 【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, a film that is less permeable to hydrogen or oxygen than a silicon oxide film can be used, such as a silicon nitride film, an aluminum oxide film, or a hafnium oxide film. 【0111】 The thickness of the insulating layer 105 in regions that do not overlap with the conductive layer 111 may be thinner than the thickness of the insulating layer 105 in regions that overlap with the conductive layer 111. In other words, the insulating layer 105 may have recesses in regions that do not overlap with the conductive layer 111. These recesses may be formed, for example, as a result of the process of forming the conductive layer 111. 【0112】 The conductive layer 102 functions as wiring. The conductive layer 102 is electrically connected to the light-emitting element 130 via the plug 106. 【0113】 Various conductive materials can be used for the conductive layer 102 and the plug 106. For example, 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 (APC, etc.) mainly composed of these materials can be used. In addition, oxides such as tin oxide or zinc oxide may be used for the conductive layer 102 and the plug 106. 【0114】 A single structure (a structure having only one light-emitting unit) can be applied to the light-emitting element 130. 【0115】 As described above, EL layer 113R, EL layer 113G, and EL layer 113B each have at least an emissive layer. For example, EL layer 113R may have an emissive layer that emits red light, EL layer 113G may have an emissive layer that emits green light, and EL layer 113B may have an emissive layer that emits blue light. 【0116】 Furthermore, EL layer 113R, EL layer 113G, and EL layer 113B may each have one or more of the following: a hole injection layer, a hole transport layer, a hole blocking layer, a charge generation layer (also called an intermediate layer), an electron blocking layer, an electron transport layer, and an electron injection layer. 【0117】 In this specification, among the layers of the EL layer, layers other than the light-emitting layer are referred to as functional layers. 【0118】 For example, if the pixel electrode of the light-emitting element 130 functions as an anode and the common electrode 115 functions as a cathode, the EL layers 113R, 113G, and 113B may have a hole injection layer, a hole transport layer, an emissive layer, and an electron transport layer in that order. That is, the EL layer 113 can be configured such that, for example, a first functional layer having a hole injection layer and a hole transport layer, an emissive layer, and a second functional layer having an electron transport layer are stacked from bottom to top. An electron blocking layer may also be present between the hole transport layer and the emissive layer. A hole blocking layer may also be present between the electron transport layer and the emissive layer. An electron injection layer may also be present 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 it may not have an electron transport layer. 【0119】 Furthermore, for example, if the pixel electrode of the light-emitting element 130 functions as a cathode and the common electrode 115 functions as an anode, the EL layers 113R, EL layer 113G, and EL layer 113B may have an electron injection layer, an electron transport layer, an emissive layer, and a hole transport layer in this order. That is, the EL layer 113 can be configured such that, for example, a first functional layer having an electron injection layer and an electron transport layer, an emissive layer, and a second functional layer having a hole transport layer are stacked from bottom to top. A hole blocking layer may also be present between the electron transport layer and the emissive layer. An electron blocking layer may also be present between the hole transport layer and the emissive layer. A hole injection layer may also be present 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 not have a hole transport layer. 【0120】 Thus, it is preferable that EL layers 113R, EL layers 113G, and EL layers 113B each have an emissive layer and a carrier transport layer on the emissive layer. Furthermore, it is preferable that EL layers 113R, EL layers 113G, and EL layers 113B each have an emissive layer and a carrier block layer on the emissive layer. Furthermore, it is preferable that EL layers 113R, EL layers 113G, and EL layers 113B each have an emissive layer, a carrier block layer on the emissive layer, and a carrier transport layer on the carrier block layer. Since the surfaces of EL layers 113R, EL layers 113G, and EL layers 113B are exposed during the manufacturing process of the display device, by providing one or both of the carrier transport layer and the carrier block layer on the emissive layer, it is possible to suppress the exposure of the emissive layer to the outermost surface and reduce the damage to the emissive layer. This can improve 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 to 180°C, more preferably 120°C to 180°C, and even more preferably 140°C to 180°C, respectively. For example, the glass transition temperature (Tg) of these compounds is preferably 100°C to 180°C, more preferably 120°C to 180°C, and even more preferably 140°C to 180°C, respectively. 【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 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 the damage it receives. 【0123】 The functional layer provided on the light-emitting layer is preferably an organic compound having a heteroaromatic ring skeleton containing one selected from a pyridine ring, a diazine ring, and a triazine ring, and a bicarbazole skeleton, or an organic compound having a condensed heteroaromatic ring skeleton containing a pyridine ring or a diazine ring, and a bicarbazole skeleton, and preferably an organic compound having a Tg of 100°C to 180°C, preferably 120°C to 180°C, and more preferably 140°C to 180°C. A functional layer using such an organic compound can have one or both functions as a hole-blocking layer and an electron-transporting layer. Note that the functional layer using such an organic compound is not limited to being located above the light-emitting layer (upper electrode side), but may also be provided below the light-emitting layer (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), and 9-[3-(4,6-diphenyl-1,3 ,5-triazine-2-yl)phenyl]-9'-phenyl-3,3'-bi-9H-carbazole (abbreviation: mPCCzPTzn), 9-[3-(4,6-diphenyl-1,3,5-triazine-2-yl)phenyl]-9'-phenyl-2,3'-bi-9H-carbazole (abbreviation: mPCCzPTzn-02), 9-[4-(4,6-diphenyl-1,3,5-triazine-2-yl)phenyl]-9'-phenyl-3,3'-bi-9H-carbazole (abbreviation: P CCzPTzn), 9-(4,6-diphenyl-1,3,5-triazine-2-yl)-9'-phenyl-3,3'-bi-9H-carbazole (abbreviation: PCCzTzn), 9-[3-(4,6-diphenyl-pyrimidine-2-yl)phenyl]-9'-phenyl-3,3'-bi-9H-carbazole (abbreviation: 2PCCzPPm), 9-(4,6-diphenyl-pyrimidine-2-yl)-9'-phenyl-2,3'-bi-9H-carbazole (abbreviation: 2PCCzPm) Examples include ), 9-(4,6-diphenylpyrimidine-2-yl)-9'-phenyl-3,3'-bi-9H-carbazole (abbreviation: 2PCCzPm-02), 4-(9'-phenyl[2,3'-bi-9H-carbazole]-9-yl)benzoflo[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. 【0125】 Furthermore, it is preferable that the heat resistance temperature of the light-emitting layer be high. This helps to prevent damage to the light-emitting layer due to heating, which can reduce luminous efficiency and shorten the lifespan. 【0126】 Furthermore, the EL layer 113R, EL layer 113G, and EL layer 113B can be configured to include, 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 a light-emitting layer and a carrier transport layer on the light-emitting layer. Alternatively, the second light-emitting unit preferably has a light-emitting layer and a carrier block layer on the light-emitting layer. Alternatively, the second light-emitting unit preferably has a light-emitting layer, a carrier block layer on the light-emitting layer, and a carrier transport layer on the carrier block layer. Since the surface of the second light-emitting unit is exposed during the manufacturing process of the display device, by providing one or both of the carrier transport layer and the carrier block layer on the light-emitting layer, it is possible to suppress the exposure of the light-emitting layer to the outermost surface and reduce the damage to the light-emitting layer. This can improve the reliability of the light-emitting element. If there are three or more light-emitting units, it is preferable that the uppermost light-emitting unit has a light-emitting layer and one or both of the carrier transport layer and the carrier block layer on the light-emitting layer. 【0128】 When the pixel electrodes of the light-emitting element 130 function as anodes and the common electrode 115 function as cathodes, 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 an electron transport layer and an electron injection layer stacked together. On the other hand, when the pixel electrodes of the light-emitting element 130 function as cathodes and the common electrode 115 function as anodes, 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 hole transport layer and a hole injection layer stacked together. The common layer 114 is shared by the light-emitting elements 130R, 130G, and 130B. 【0129】 Furthermore, the common electrode 115 is shared by the light-emitting element 130R, light-emitting element 130G, and light-emitting element 130B, similar to the common layer 114. 【0130】 The common electrode 115 can be formed continuously after the common layer 114 has been formed, without any intermediate steps 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 to the atmosphere. In other words, the common layer 114 and the common electrode 115 can be formed in a continuous vacuum. As a result, the underside of the common electrode 115 can be made cleaner than when the display device 100 does not have a common layer 114. Therefore, the light-emitting element 130 can be made into a light-emitting element with high reliability and good characteristics. 【0131】 Furthermore, in the example shown in Figure 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 portion of the mask layer that remained after being provided in contact with the upper surface of the EL layer 113R when the EL layer 113R was processed. Similarly, the mask layer 118G is a portion of the mask layer that remained after being provided when the EL layer 113G was formed, and the mask layer 118B is a portion of the mask layer that remained after being provided when the EL layer 113B was formed. Thus, the display device 100 may have a portion of the mask layer that remains after being used to protect the EL layer during its manufacture. 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 for each other. In the following, mask layer 118R, mask layer 118G, and mask layer 118B may be collectively referred to as mask layer 118. 【0132】 In Figure 2A, one end of the mask layer 118R is aligned with, or approximately aligned with, the 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 more likely to be formed on the approximately flat surface of the EL layer 113R. The same applies to the mask layer 118G and the mask layer 118B. Furthermore, the mask layer 118 remains, for example, between the upper surface of the island-shaped EL layer 113 and the insulating layer 125. 【0133】 Furthermore, if the edges are aligned or roughly aligned, and the top surface shapes match or roughly match, then in a plan view, at least a portion of the contours overlap between the stacked layers. The case where at least a portion of the contours overlap between the upper and lower layers includes, for example, cases where the upper and lower layers are processed with the same mask pattern, or partially with the same mask pattern. However, strictly speaking, the contours may not overlap, and the upper layer may be located inside the lower layer, or the upper layer may be located outside the lower layer; in this case as well, the edges are said to be roughly aligned, or the top surface shapes roughly match. 【0134】 Each side of EL layer 113R, EL layer 113G, and EL layer 113B is covered by insulating layer 125. Insulating layer 127 overlaps with each side of EL layer 113R, EL layer 113G, and EL layer 113B via insulating layer 125. 【0135】 Furthermore, portions of the upper surfaces of EL layer 113R, EL layer 113G, and EL layer 113B are covered by the mask layer 118. The insulating layer 125 and insulating layer 127 overlap portions of the upper surfaces of EL layer 113R, EL layer 113G, and EL layer 113B via the mask layer 118. 【0136】 Since a portion of the upper surface and sides of the EL layer 113R, EL layer 113G, and EL layer 113B are covered by at least one of the insulating layer 125, insulating layer 127, and mask layer 118, contact between the common layer 114 and the common electrode 115 and the sides of the EL layer 113R, EL layer 113G, and EL layer 113B is suppressed, thereby suppressing a short circuit of the light-emitting element 130. This improves the reliability of the light-emitting element 130. 【0137】 The film thicknesses of the EL layer 113R, EL layer 113G, and EL layer 113B can be made different. For example, it is preferable to set the film thickness to correspond to the optical path length that intensifies the light emitted by each of the EL layers 113R, EL layer 113G, and EL layer 113B. This makes it possible to realize a micro-optical resonator (microcavity) structure and improve the color purity of the light emitted from the sub-pixel 110. 【0138】 The insulating layer 125 is preferably in contact with the respective sides of the EL layers 113R, 113G, and 113B. This suppresses delamination of the EL layers 113R, 113G, and 113B. The close contact between the insulating layer 125 and the EL layers 113R, 113G, or 113B provides the effect of fixing or bonding adjacent EL layers 113 to each other. This improves the reliability of the light-emitting element 130 and increases the manufacturing yield of the light-emitting element. 【0139】 Furthermore, as shown in Figure 2A, by having insulating layers 125 and 127 cover both a portion of the upper surface and the sides of EL layers 113R, 113G, and 113B, peeling of the EL layer 113 can be more effectively suppressed, and the reliability of the light-emitting element 130 can be more effectively improved. In addition, the manufacturing yield of the light-emitting element 130 can be more effectively improved. 【0140】 Figure 2A shows an example where a laminated structure of EL layer 113R, mask layer 118R, insulating layer 125, and insulating layer 127 is located on the edge of conductive layer 112R. Similarly, a laminated structure of EL layer 113G, mask layer 118G, insulating layer 125, and insulating layer 127 is located on the edge of conductive layer 112G, and a laminated structure of EL layer 113B, mask layer 118B, insulating layer 125, and insulating layer 127 is located on the edge of conductive layer 112B. 【0141】 Figure 2A shows a configuration in which the EL layer 113R covers the edge of the conductive layer 112R, and the insulating layer 125 has a region in contact with the side surface of the EL layer 113R. Similarly, the edge of the conductive layer 112G is covered with the EL layer 113G, the edge 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 the recesses formed in the insulating layer 125. The insulating layer 127 can be configured to overlap a portion of the upper surface and side surfaces of the EL layers 113R, EL layer 113G, and EL layer 113B, respectively, via the insulating layer 125. Preferably, the insulating layer 127 covers at least a portion of the side surfaces of the insulating layer 125. 【0143】 By providing insulating layers 125 and 127, the gaps between adjacent island-shaped layers can be filled, thereby reducing extreme irregularities on the surfaces of the layers formed on the island-shaped layers, specifically the common layer 114 and the common electrode 115, and making them flatter. Consequently, the coverage of the common layer 114 and the common electrode 115 can be improved. 【0144】 The common layer 114 and common electrode 115 are provided on the EL layer 113R, EL layer 113G, EL layer 113B, mask layer 118, insulating layer 125, and insulating layer 127. Before the insulating layers 125 and 127 are provided, a step difference occurs due to the region where the pixel electrode and island-shaped EL layer 113 are provided and the region where the pixel electrode and island-shaped EL layer 113 are not provided (the region between the light-emitting elements 130). The display device 100 can flatten this step difference by having the insulating layers 125 and 127, and can improve the coverage of the common layer 114 and common electrode 115. Therefore, connection failures due to step breaks can be suppressed. In addition, it is possible to suppress the local thinning of the common electrode 115 due to the step difference and the increase in electrical resistance. 【0145】 The upper surface of the insulating layer 127 preferably has a shape that is more flat, but it may also have convex portions, convex curved surfaces, concave curved surfaces, or recesses. For example, the upper surface of the insulating layer 127 preferably has a 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 the recesses formed in the insulating layer 125. The insulating layer 127 is provided between island-shaped EL layers 113. In other words, the display device 100 employs a process (hereinafter referred to as process 1) in which island-shaped EL layers 113 are formed, and then an 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】 Process 1 is preferable to Process 2 because it allows for a wider margin. More specifically, Process 1 provides a wider margin for alignment accuracy between different patterns and a display device with less variation in characteristics compared to Process 2. Since the manufacturing method for the display device 100 is a process similar to Process 1, it is possible to provide a display device with less variation and high display quality. 【0148】 Next, we will describe examples of materials for the insulating layer 125 and the insulating layer 127. 【0149】 The insulating layer 125 can be an insulating layer having an inorganic material. For example, an inorganic insulating film such as an oxide insulating film, a nitride insulating film, an oxidative nitride insulating film, or an oxidative nitride insulating film can be used for the insulating layer 125. The insulating layer 125 may be a single layer structure or a laminated structure. Examples of oxide insulating films include silicon oxide film, aluminum oxide film, magnesium oxide film, indium gallium zinc oxide film, gallium oxide film, germanium oxide film, yttrium oxide film, zirconium oxide film, lanthanum oxide film, neodymium oxide film, hafnium oxide film, and tantalum oxide film. Examples of nitride insulating films include silicon nitride film and aluminum nitride film. Examples of oxidative nitride insulating films include silicon oxidative nitride film and aluminum oxidative nitride film. Examples of oxidative nitride insulating films include silicon nitride film and aluminum nitride film. In particular, aluminum oxide is preferred because it has a high selectivity ratio with the EL layer 113 during etching and has the function of protecting the EL layer 113 during the formation of the insulating layer 127, which will be described later. In particular, by applying 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) to the insulating layer 125, an insulating layer 125 with fewer pinholes and excellent protection for the EL layer 113 can be formed. Alternatively, the insulating layer 125 may have a laminated structure of a film formed by ALD and a film formed by sputtering. For example, the insulating layer 125 may have a laminated structure of an aluminum oxide film formed by ALD and a silicon nitride film formed by sputtering. 【0150】 Preferably, the insulating layer 125 functions as a barrier insulating layer against at least one of water and oxygen. Furthermore, preferably, the insulating layer 125 has the function of suppressing the diffusion of at least one of water and oxygen. Also, preferably, the insulating layer 125 has the function of capturing or fixing (also known as gettering) at least one of water and oxygen. 【0151】 In this specification, the term "barrier insulating layer" refers to an insulating layer that has barrier properties. Furthermore, in this specification, "barrier properties" refers to the function of suppressing the diffusion of the corresponding substance (also known as low permeability), or the function of capturing or fixing the corresponding substance. 【0152】 The insulating layer 125 has the function of a barrier insulating layer or a gettering function, thereby suppressing the intrusion of impurities that could diffuse from the outside into the light-emitting element 130, typically water and at least one of oxygen. This configuration makes it possible to provide a highly reliable light-emitting element and, furthermore, a highly reliable display device. 【0153】 Furthermore, it is preferable that the insulating layer 125 has a low impurity concentration. This prevents impurities from mixing from the insulating layer 125 into the EL layer 113 and degrading the EL layer 113. In addition, by lowering the impurity concentration in the insulating layer 125, the barrier properties against at least one of water and oxygen can be improved. For example, it is desirable that the insulating layer 125 has a sufficiently low hydrogen concentration and a sufficiently low carbon concentration, preferably both. 【0154】 Furthermore, the same material can be used for the insulating layer 125 and the mask layers 118R, 118G, and 118B. In this case, the boundary between any of the mask layers 118R, 118G, and 118B and the insulating layer 125 may become unclear and indistinguishable. Therefore, the insulating layer 125 may be identified as a single layer with any of the mask layers 118R, 118G, and 118B. In other words, it may be observed that a single layer is provided in contact with a portion of the upper surface and side surface of each of the EL layers 113R, 113G, and 113B, and that the insulating layer 127 covers at least a portion of the side surface of that single layer. 【0155】 The insulating layer 127, provided on the insulating layer 125, has the function of flattening the extreme irregularities in 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 forming the common electrode 115. 【0156】 As the insulating layer 127, an insulating layer having an organic material can be suitably used. As the organic material, a photosensitive material, such as a photosensitive organic resin, is preferred, and a photosensitive resin composition containing an acrylic resin is preferred. In this specification, the term "acrylic resin" does not refer only to polymethacrylate esters or methacrylic resins, but may refer to acrylic polymers in a broad sense. 【0157】 Furthermore, the insulating layer 127 may be acrylic resin, polyimide resin, epoxy resin, imide resin, polyamide resin, polyimidoamide resin, silicone resin, siloxane resin, benzocyclobutene resin, phenol resin, or precursors of these resins. Alternatively, the insulating layer 127 may be an organic material such as polyvinyl alcohol (PVA), polyvinyl butyral, polyvinylpyrrolidone, polyethylene glycol, polyglycerin, pullulan, water-soluble cellulose, or alcohol-soluble polyamide resin. A photoresist may also be used as the photosensitive resin. Either a positive-type or 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. By absorbing the light emitted from the light-emitting element 130, the insulating layer 127 can suppress light leakage (stray light) from the light-emitting element 130 to adjacent light-emitting elements 130 through the insulating layer 127. 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, light-absorbing resin materials such as polyimide, and resin materials that can be used in colored layers (color filter materials). In particular, it is preferable to use a resin material which is laminated or mixed with two or more color filter materials, as this can enhance the visible light shielding effect. In particular, by mixing three or more color filter materials, it is possible to create a black or near-black resin layer. 【0160】 Furthermore, it is preferable that the material used for the insulating layer 127 has a low volume shrinkage rate. This makes it easier to form the insulating layer 127 in a desired shape. It is also preferable that the insulating layer 127 has a low volume 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 volume shrinkage rate of the insulating layer 127 after heat curing, after photocuring, or after both photocuring and heat curing is preferably 10% or less, more preferably 5% or less, and even more preferably 1% or less. Here, the volume shrinkage rate can be the value of either the volume shrinkage rate due to light irradiation or the volume shrinkage rate due to heating, or the sum of both. 【0161】 By providing a protective layer 131 on the light-emitting element 130, the reliability of the light-emitting element 130 can be improved. The protective layer 131 may be a single layer or a laminated structure of two or more layers. 【0162】 The conductivity of the protective layer 131 is not required. At least one of an insulating film, a semiconductor film, and a conductive film can be used as the protective layer 131. 【0163】 The protective layer 131 can be an inorganic insulating film such as an oxide insulating film, a nitride insulating film, an oxidoxide-nitrided insulating film, or an oxide-nitrided insulating film. Specific examples of these inorganic insulating films are given in the description of the insulating layer 125. In particular, the protective layer 131 preferably has a nitride insulating film or an oxide-nitrided insulating film, and more preferably a nitride insulating film. 【0164】 Furthermore, the protective layer 131 may also be an inorganic film containing In-Sn oxide (also known as ITO), In-Zn oxide, Ga-Zn oxide, Al-Zn oxide, or indium gallium zinc oxide (In-Ga-Zn oxide, also known as IGZO). The inorganic film is preferably highly resistive, and more specifically, it is preferably more resistive than the common electrode 115. The inorganic film may further contain nitrogen. 【0165】 The presence of an inorganic film in the protective layer 131 suppresses oxidation of the common electrode 115. Furthermore, the presence of an inorganic film in the protective layer 131 prevents impurities such as water and oxygen from entering the light-emitting element 130. As a result, the light-emitting element 130 can be made less prone to degradation, and the display device 100 can be made a highly reliable display device. 【0166】 When the light emitted from the light-emitting element 130 is extracted via a protective layer 131, it is preferable that the protective layer 131 has high transmittance to visible light. For example, ITO, IGZO, and aluminum oxide are preferred because they are inorganic materials that each have high transmittance to visible light. 【0167】 As the protective layer 131, for example, a laminated structure of an aluminum oxide film and a silicon nitride film on the aluminum oxide film, or a laminated structure of an aluminum oxide film and an IGZO film on the aluminum oxide film can be used. By using such a laminated structure, it is possible to suppress the intrusion of impurities such as water and oxygen into 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 organic insulating materials that can be used for the insulating layer 127. 【0169】 The protective layer 131 may have a two-layer structure formed using different film deposition methods. Specifically, the first layer of the protective layer 131 may be formed using the ALD method, and the second layer of the protective layer 131 may be formed using 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 components can also be placed on the outside of the substrate 120. Examples of optical components include polarizing plates, phase difference plates, light-diffusing layers such as diffusion films, anti-reflective layers, and light-collecting films. Furthermore, surface protection layers such as an antistatic film to suppress dust adhesion, a water-repellent film to prevent dirt from adhering, a hard coat film to suppress scratches during use, or an impact-absorbing layer may be placed on the outside of the substrate 120. For example, a glass layer or a silica layer (SiO₂) may be used as the surface protection layer. x By providing a protective layer, surface contamination and scratching can be suppressed, which is preferable. Furthermore, as a surface protective layer, DLC (diamond-like carbon), aluminum oxide (AlO2) are preferable. x ), polyester-based materials, or polycarbonate-based materials may be used. It is preferable to use a material with high transmittance to visible light for the surface protective layer. Furthermore, it is preferable to use a material with high hardness for the surface protective layer. 【0171】 The substrate 120 can be made of glass, quartz, ceramic, sapphire, resin, metal, alloy, or semiconductor. The substrate on the side that extracts light from the light-emitting element should be made of a material that transmits the light. 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】 As the substrate 120, polyester resins 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 or aramid, etc.), polysiloxane resin, cycloolefin resin, polystyrene resin, polyamide-imide resin, polyurethane resin, polyvinyl chloride resin, polyvinylidene chloride resin, polypropylene resin, polytetrafluoroethylene (PTFE) resin, ABS resin, or cellulose nanofiber can be used. Glass with a thickness sufficient to provide flexibility may also be used for the substrate 120. 【0173】 Furthermore, when a circular polarizing plate is superimposed on a display device, it is preferable to use a substrate with high optical isotropy for the substrate of the display device. A substrate with high optical isotropy has low birefringence, or more specifically, a small amount of birefringence. 【0174】 For substrates with high optical isotropy, the absolute value of the retardation (phase difference) 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 triacetylcellulose (TAC, also known as cellulose triacetate) film, cycloolefin polymer (COP) film, cycloolefin copolymer (COC) film, and acrylic film. 【0176】 Furthermore, when a film is used as the substrate, the film may absorb water, potentially causing wrinkles or other shape changes in the display device. For this reason, it is preferable to use a film with a low water absorption rate as the substrate. For example, it is preferable to use a film with a water absorption rate of 1% or less, more preferable to use a film with a water absorption rate of 0.1% or less, and even more preferable to use a film with a water absorption rate of 0.01% or less. 【0177】 As the resin layer 122, various curing adhesives can be used, such as UV-curing adhesives, reaction-curing adhesives, thermosetting adhesives, or anaerobic adhesives. Examples of these adhesives include epoxy resins, acrylic resins, silicone resins, phenolic resins, polyimide resins, imide resins, PVC (polyvinyl chloride) resins, PVB (polyvinyl butyral) resins, and EVA (ethylene vinyl acetate) resins. Materials with low moisture permeability, such as epoxy resins, are particularly preferred. Two-component mixed resins may also be used. Alternatively, for example, an adhesive sheet may be used. 【0178】 Figure 2B1 is a cross-sectional view showing an example of the configuration of conductive layers 111 and 112. Note that Figure 2B1 also shows the insulating layer 105. The same applies to other drawings showing examples of the configuration of conductive layers 111 and 112. 【0179】 As shown in Figure 2B1, the conductive layer 111 can have a configuration comprising a conductive layer 111a on the insulating layer 105, a conductive layer 111b on the conductive layer 111a, and a conductive layer 111c on the conductive layer 111b. Furthermore, a conductive layer 112 is provided so as to cover the upper 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】 In the example shown in Figure 2B1, the conductive layer 111b is sandwiched between conductive layers 111a and 111c. Materials less susceptible to deterioration than conductive layer 111b can be used for conductive layer 111a and conductive layer 111c. For example, conductive layer 111a can be made of a material less prone to migration due to contact with insulating layer 105 than conductive layer 111b. Furthermore, conductive layer 111c can be made of a material less susceptible to oxidation than conductive layer 111b, and whose oxide electrical resistivity is lower than that of the oxide material used for conductive layer 111b. 【0181】 In this specification, migration refers to either stress migration or electromigration, or both. Stress migration is a phenomenon in which stress is generated in the conductive layer during heat treatment due to the difference in thermal expansion coefficients between the conductive layer and the insulating layer or other layer in contact with the conductive layer, causing atoms contained in the conductive layer to move. Electromigration is a phenomenon in which atoms contained in the conductive layer move due to an electric field. Due to migration, the conductive layer may develop hillocks, which are raised areas on the surface, or voids, which are cavities. The formation of hillocks may cause the conductive layer to short-circuit with other conductive layers, and the formation of voids may cause the conductive layer to split. 【0182】 As described above, by sandwiching the conductive layer 111b between conductive layers 111a and 111c, the range of material selection for the conductive layer 111b can be broadened. This allows, for example, the conductive layer 111b to have a higher reflectivity to visible light than at least one of the conductive layers 111a and 111c. For example, aluminum can be used as the conductive layer 111b. Note that an alloy containing aluminum may also be used for the conductive layer 111b. Furthermore, titanium can be used as the conductive layer 111a, as it has a lower reflectivity to visible light compared to aluminum, but is less prone to migration than aluminum even when in contact with the insulating layer 105. In addition, titanium can be used as the conductive layer 111c, as it has a lower reflectivity to visible light compared to aluminum, but is less prone to oxidation than aluminum, and the electrical resistivity of its oxide is lower than that of aluminum oxide. 【0183】 As described above, by making the conductive layer 111 a laminated structure of multiple layers, the characteristics of the display device can be improved. For example, the display device 100 can be made into a display device with high light extraction efficiency and high reliability. 【0184】 Figure 2B2 shows a modified configuration of the one shown in Figure 2B1, in which the conductive layer 112 has a conductive layer 112a that covers the upper surface of conductive layer 111c, the side surface of conductive layer 111c, the side surface of conductive layer 111b, and the side surface of conductive layer 111a, and a conductive layer 112b on the conductive layer 112a. 【0185】 The conductive layer 112a can be made of the same material as the conductive layer 111c. The conductive layer 112b can be made of the same material as the conductive layer 112 shown in Figure 2B1. In other words, a metallic material such as titanium can be used as the conductive layer 112a, and a conductive oxide such as indium tin oxide can be used as the conductive layer 112b. 【0186】 By configuring the conductive layer 112 as shown in Figure 2B2, it is possible to suppress contact between the conductive layer 112b, which can use a conductive oxide such as indium tin oxide, and the side surface of the conductive layer 111b, which can use, for example, aluminum. This effectively suppresses deterioration of the conductive layer 111b and improves the reliability of the display device 100. Even when the conductive layer 112 is configured as shown in Figure 2B2, it is preferable to provide a conductive layer 111c. This prevents oxidation by oxygen in the atmosphere on the upper surface of the conductive layer 111b, which has a higher reflectivity to visible light than the conductive layer 111a, after the formation of the conductive layer 111 and before the formation of the conductive layer 112. Therefore, a decrease in the reflectivity of the conductive layer 111 to visible light can be suppressed. As a result, the display device 100 can be made into a display device with high light extraction efficiency. 【0187】 Furthermore, as shown in Figure 2B2, when the conductive layer 112 has a laminated structure of conductive layer 112a and conductive layer 112b, a conductive oxide such as indium tin oxide may be used for conductive layer 112a, and a mixed material such as molybdenum oxide and an organic material may be used for conductive layer 112b. 【0188】 Here, if the conductive layer 111 has the configuration shown in Figures 2B1 and 2B2, in a cross-sectional view, for example, the edge of conductive layer 111b may be located inward from the edge of conductive layer 111c. In other words, in a cross-sectional view, conductive layer 111c may have a region that protrudes from conductive layer 111b. In this case, if conductive layer 112 is formed using a film deposition method with low coverage, the protruding region may cause a step break in the conductive layer 112. Also, the conductive layer 112 may become locally thinner, increasing its electrical resistance. 【0189】 Therefore, if the conductive layer 112 is formed using a film deposition method with high coverage, the occurrence of connection failures due to stepped breaks in the conductive layer 112 and the increase in electrical resistance due to localized thinning of the conductive layer 112 can be suppressed. For example, if the conductive layer 112 is formed using the ALD method, even if the conductive layer 111c has a region that protrudes from the conductive layer 111b, the occurrence of connection failures due to stepped breaks in the conductive layer 112 and the increase in electrical resistance due to localized thinning of the conductive layer 112 can be suitably suppressed. 【0190】 Figure 3A is a cross-sectional view showing a different configuration example of the conductive layer 111 and conductive layer 112 from those shown in Figures 2B1 and 2B2. As shown in Figure 3A, the conductive layer 111 can have a configuration comprising a conductive layer 111a on the insulating layer 105 and a conductive layer 111b on the conductive layer 111a. In other words, the conductive layer 111 shown in Figure 3A has a two-layer laminated structure. In this way, when the conductive layer 111 has a laminated structure of multiple layers, the reflectance for visible light of at least one of the layers constituting the conductive layer 111 is higher than the reflectance for visible light of the conductive layer 112. Furthermore, the conductive layer 112 is provided so as to cover the side and top surfaces of the conductive layer 111a and conductive layer 111b. 【0191】 As mentioned above, it is preferable that the sides of the conductive layer 111 have a tapered shape. Specifically, it is preferable that the sides of the conductive layer 111 have a tapered shape with a taper angle of less than 90°. For example, in the conductive layer 111 configuration shown in Figure 3A, it is preferable that at least one side of the conductive layer 111a and the conductive layer 111b has a tapered shape. For example, it is preferable that the side of the conductive layer 111a has a tapered shape. Alternatively, it is preferable that both the side of the conductive layer 111a and the side of the conductive layer 111b have a tapered shape. 【0192】 Figure 3B shows a modified configuration of the one shown in Figure 3A, in which the conductive layer 112 has a two-layer laminated structure consisting of conductive layer 112a and conductive layer 112b on conductive layer 112a. The conductive layer 112a can be made of the same material as that used for conductive layer 111. The conductive layer 112b can be made of the same material as that used for conductive layer 112 shown in Figure 3A, for example. 【0193】 For example, silver or a silver-containing alloy can be used as the conductive layer 112a. Silver and silver-containing alloys have the characteristic of having a higher reflectivity to visible light than, for example, titanium. Furthermore, silver is less prone to oxidation than aluminum, which can be used in the conductive layer 111b, and the electrical resistivity of silver oxide is lower than that of aluminum oxide. As a result, by using silver or a silver-containing alloy as the conductive layer 112a, the reflectivity of the pixel electrode to visible light can be suitably increased while suppressing the increase in the electrical resistance of the pixel electrode due to oxidation of the conductive layer 112a. Thus, the display device 100 can be made into 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 reflectivity to visible light, as the conductive layer 112a. This can suitably increase the light extraction efficiency of the display device 100. 【0194】 Alternatively, titanium may be used as the conductive layer 112a. Since titanium has better processability by etching than silver, using titanium as the conductive layer 112a makes it easy to form the conductive layer 112a. 【0195】 Furthermore, the conductive layer 111 does not necessarily have to have a conductive layer 111b. In other words, the conductive layer 111 can have a single-layer structure of conductive layer 111a. For example, titanium, which can be used for conductive layer 111a, is less prone to oxidation than aluminum, which can be used for conductive layer 111b, and the electrical resistivity of titanium oxide is lower than that of aluminum oxide. Therefore, by having conductive layer 111 without conductive layer 111b, the electrical resistance at the contact interface between conductive layer 111 and conductive layer 112 can be reduced. 【0196】 Figure 4A is a cross-sectional view showing a different configuration example of the conductive layer 111 and conductive layer 112 from those shown in Figures 2B1, 2B2, 3A, and 3B. In the example shown in Figure 4A, the conductive layer 111 has a single-layer structure. The conductive layer 112 has a three-layer laminated structure consisting of conductive layer 112a, conductive layer 112b on conductive layer 112a, and conductive layer 112c on conductive layer 112b. 【0197】 The conductive layer 111 shown in Figure 4A is made of a material that is less susceptible to oxidation even when in contact with the conductive layer 112a, and even if it does oxidize, its electrical resistivity does not increase significantly. For example, an alloy containing titanium can be used as the conductive layer 111. As a result, deterioration of the conductive layer 111 is suppressed, and the display device 100 can be made into a highly reliable display device. 【0198】 The conductive layer 112a shown in Figure 4A is a layer that has higher adhesion to the conductive layer 112b, for example, to the insulating layer 105. A conductive oxide can be used as such a conductive layer 112a, and for example, an oxide having one or more selected from indium, tin, zinc, gallium, titanium, aluminum, and silicon can be used. Specifically, for example, indium tin oxide or silicon-containing indium tin oxide can be used as the conductive layer 112a. This suppresses peeling of the conductive layer 112b, making the display device 100 a highly reliable display device. Note that, as shown in Figure 4A, the conductive layer 112a can be in contact with the insulating layer 105, while the conductive layer 112b can not be in contact with the insulating layer 105. 【0199】 The conductive layer 112b shown in Figure 4A is a layer whose reflectance to visible light is higher than that of conductive layers 111, 112a, and 112c. The reflectance of 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 made into a display device with high light extraction efficiency. 【0200】 When conductive layers 111 and 112 function as anodes, conductive layer 112c is a layer with a large work function. For example, conductive layer 112c is a layer with a larger work function than conductive layer 112b. This allows the driving voltage of the light-emitting element 130 to be lowered. For conductive layer 112c, for example, a material similar to the material that can be used for conductive layer 112a can be used. For example, the same type of material can be used for conductive layer 112a and conductive layer 112c. For example, if indium tin oxide is used for conductive layer 112a, indium tin oxide can also be used for conductive layer 112c. 【0201】 Furthermore, when conductive layers 111 and 112 function as cathodes, conductive layer 112c is a layer with a small work function. For example, conductive layer 112c is a layer with a smaller work function than conductive layer 112b. This allows the driving voltage of the light-emitting element 130 to be lowered. 【0202】 Furthermore, it is preferable that the conductive layer 112c be a layer with high transmittance to visible light. For example, it is preferable that the transmittance of the conductive layer 112c to visible light is higher than the transmittance 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% or more and 100% or less, preferably 70% or more and 100% or less, and more preferably 80% or more and 100% or less. As a result, the amount of light absorbed by the conductive layer 112c from the light emitted by the EL layer 113 can be reduced. Also, as mentioned above, the conductive layer 112b below the conductive layer 112c can be a layer with high reflectance to visible light. Therefore, the display device 100 can be a display device with high light extraction efficiency. 【0203】 Furthermore, the conductive layer 112b shown in Figure 4A is a layer with high reflectivity to the light emitted by the EL layer 113, and the conductive layer 112c is a layer with high transmittance to the light emitted by the EL layer 113. For example, if the EL layer 113 emits infrared light, the conductive layer 112b is a layer with high reflectivity to infrared light, and the conductive layer 112c is a layer with high transmittance to infrared light. For example, if the EL layer 113 emits infrared light, then in the above description of the conductive layer 112b and conductive layer 112c shown in Figure 4A, visible light can be read as infrared light. 【0204】 As a result, the display device 100 can be a display device that is highly reliable and has high light extraction efficiency. Furthermore, the display device 100 can be a display device that has a light-emitting element with high luminous efficiency. 【0205】 Figures 4B and 4C are cross-sectional views showing different configurations of conductive layers 111 and 112 from those shown in Figure 4A. In the example shown in Figure 4B, conductive layer 111 has a two-layer laminated structure consisting of conductive layer 111a and conductive layer 111b on conductive layer 111a. In the example shown in Figure 4C, conductive layer 111 has a three-layer laminated structure consisting of conductive layer 111a, conductive layer 111b on conductive layer 111a, and conductive layer 111c on conductive layer 111b. 【0206】 The conductive layers 111a and 111c can be made of the same materials as conductive layer 111 shown in Figure 4A, for example, titanium or an alloy containing titanium. Conductive layer 111b can be made to have a higher reflectivity to visible light than conductive layer 111a. Also, conductive layer 111b can be made to have higher etching processability than conductive layer 112b. As a result, the reflectivity of the pixel electrode to visible light can be increased while the thickness of conductive layer 112b, which can be made of silver or an alloy containing silver, can be reduced. Thus, the display device 100 can be made to have high light extraction efficiency and can be easily manufactured. For example, aluminum or an aluminum alloy can be used as conductive layer 111b. 【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 and its surrounding area between EL layer 113R and EL layer 113G. In the following explanation, the insulating layer 127 between EL layer 113R and EL layer 113G will be used as an example, but the same applies to the insulating layer 127 between EL layer 113G and EL layer 113B, and the insulating layer 127 between EL layer 113B and EL layer 113R, etc. Figure 5B is an enlarged view of the end of the insulating layer 127 on EL layer 113G and its vicinity, as shown in Figure 5A. In the following explanation, the end of the insulating layer 127 on EL layer 113G will be used as an example, but the same applies to the end of the insulating layer 127 on EL layer 113R, and the end of the insulating layer 127 on EL layer 113B, etc. 【0208】 As shown in Figure 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 part of the upper surface of the EL layer 113R, and a mask layer 118G is provided in contact with a part of the upper surface of the EL layer 113G. An insulating layer 125 is provided such that it has 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 part of the upper and side surfaces of the EL layer 113R and a part of the upper and side surfaces of the EL layer 113G via the insulating layer 125, and is in contact with at least a part of the upper and side surfaces of the insulating layer 125. A common layer 114 is provided covering the EL layer 113R, mask layer 118R, EL layer 113G, mask layer 118G, insulating layer 125, and insulating layer 127, and a common electrode 115 is provided on the common layer 114. 【0209】 As shown in Figure 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 recesses in the region that does not overlap with the EL layer 113. These recesses are formed, for example, as a result of the EL layer 113 formation process. 【0210】 Furthermore, the insulating layer 127 is formed in the region between the two island-shaped EL layers 113 (for example, in Figure 5A, the region between EL layer 113R and EL layer 113G). At this time, at least a portion of the insulating layer 127 is positioned between the side edge of one EL layer 113 (for example, EL layer 113R in Figure 5A) and the side edge of the other EL layer 113 (for example, EL layer 113G in Figure 5A). By providing such an insulating layer 127, it is possible to suppress the formation of discontinuities and locally thin areas in the common layer 114 and common electrode 115 formed on the island-shaped EL layers 113 and on the insulating layer 127. 【0211】 As shown in Figure 5B, the insulating layer 127 preferably has a tapered shape with a taper angle θ1 at its end 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, it is not limited to the substrate surface; it may also be the angle between 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 and the side surface of the insulating layer 127. 【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 making the edges of the insulating layer 127 have such a forward taper shape, the common layer 114 and common electrode 115 provided on the insulating layer 127 can be formed with good coverage, and the occurrence of step breaks or localized thinning can be suppressed. As a result, the in-plane uniformity of the common layer 114 and common electrode 115 can be improved, and the display quality of the display device can be improved. 【0213】 Furthermore, as shown in Figure 5A, in a cross-sectional view of the display device 100, it is preferable that the upper surface of the insulating layer 127 has a convex curved shape. It is preferable that the convex curved shape of the upper surface of the insulating layer 127 is a shape that bulges gently towards the center. It is also preferable that the convex curved portion at the center of the upper surface of the insulating layer 127 is smoothly connected to the tapered portion at the end. By making the insulating layer 127 such a shape, the common layer 114 and the common electrode 115 can be formed on the entire insulating layer 127 with good coverage. 【0214】 As shown in Figure 5B, it is preferable that the edge of the insulating layer 127 is located outside the edge of the insulating layer 125. This effectively reduces the surface irregularities forming the common layer 114 and the common electrode 115, thereby improving the coverage of the common layer 114 and the common electrode 115. 【0215】 As shown in Figure 5B, the insulating layer 125 preferably has a tapered shape with a taper angle θ2 at its end 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, it is not limited to the substrate surface; it may also be the angle between 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 and the side surface of the insulating layer 125. 【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】 The mask layer 118G preferably has a tapered shape with a taper angle θ3 at its end in a cross-sectional view of the display device 100, as shown in Figure 5B. The taper angle θ3 is the angle between the side surface of the mask layer 118G and the substrate surface. However, it is not limited to the substrate surface; it may also be the angle between 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 and the side surface of the mask layer 118G. 【0218】 The taper angle θ3 of the mask layer 118G is less than 90°, preferably 60° or less, more preferably 45° or less, and even more preferably 20° or less. By giving the mask layer 118G such a forward taper shape, the common layer 114 and the common electrode 115 provided on the mask layer 118G can be formed with good coverage. 【0219】 It is preferable that the edges of the mask layer 118R and the mask layer 118G are located outside the edges of the insulating layer 125. This reduces the surface irregularities forming the common layer 114 and the common electrode 115, thereby improving the coverage of the common layer 114 and the common electrode 115. 【0220】 As will be explained in detail later, if the etching process of the insulating layer 125 and the mask layer 118 is performed at the same time, side etching may cause the insulating layer 125 and the mask layer 118 beneath the edge of the insulating layer 127 to disappear, forming a cavity. This cavity can cause unevenness on the surface forming the common layer 114 and the common electrode 115, making it easier for the common layer 114 and the common electrode 115 to break down. Therefore, by performing the etching process in two stages and performing a heat treatment between the two etching stages, even if a cavity is formed in the first etching stage, the insulating layer 127 will deform due to the heat treatment, and the cavity can be filled. In addition, since the second etching stage involves etching a thin film, the amount of side etching is reduced, making it less likely for a cavity to form, or if a cavity does form, it can be made extremely small. Therefore, it is possible to suppress the formation of unevenness on the surface forming the common layer 114 and the common electrode 115, and to suppress the breaking down of the common layer 114 and the common electrode 115. Because the etching process is performed twice, the taper angles θ2 and θ3 may be different angles. Alternatively, taper angles θ2 and θ3 may be the same angle. Furthermore, taper angles θ2 and θ3 may each be smaller than 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, Figure 5B shows an example where the insulating layer 127 in contact with and covers the inclined surface located at the edge of the mask layer 118G formed by the first etching process, while the inclined surface located at the edge of the mask layer 118G formed by the second etching process is exposed. These two inclined surfaces can sometimes be distinguished by their 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】 Furthermore, Figures 6A and 6B show modified configurations of those shown in Figures 5A and 5B, illustrating an example where the insulating layer 127 covers the entire side surface of the mask layer 118R and the entire side surface of the mask layer 118G. Specifically, in Figure 6B, the insulating layer 127 covers both of the two inclined surfaces in contact with each other. This is preferable because it further reduces the unevenness of the surfaces forming the common layer 114 and the common electrode 115. Figure 6B shows an example where the edge of the insulating layer 127 is located outside the edge of the mask layer 118G. The edge of the insulating layer 127 may be located inside the edge of the mask layer 118G, as shown in Figure 6B, and may be aligned with or approximately aligned with the edge of the mask layer 118G. Also, as shown in Figure 6B, the insulating layer 127 may be in contact with the EL layer 113G. 【0223】 Furthermore, Figures 7A and 8A are modified versions of the configuration shown in Figure 5A, and Figures 7B and 8B are modified versions of the configuration shown in Figure 5B. Figures 7A, 7B, 8A, and 8B show examples in which the insulating layer 127 has a concave curved shape (also called a constricted portion, recess, indentation, or depression, etc.) on its side surface. Depending on the material of the insulating layer 127 and the formation conditions (heating temperature, heating time, and heating atmosphere, etc.), a concave curved shape may be formed on the side surface of the insulating layer 127. 【0224】 Figures 7A and 7B show examples where the insulating layer 127 covers a portion of the side surface of the mask layer 118G, leaving the rest of the side surface of the mask layer 118G exposed. Figures 8A and 8B show examples where the insulating layer 127 is in contact with and covers the entire side surface of the mask layer 118G. 【0225】 In the configurations shown in Figures 6B, 7B, and 8B, it is preferable that the taper angles θ1 to θ3 are within the above ranges. 【0226】 Furthermore, as shown in Figures 5A, 6A, 7A, and 8A, it is preferable that one end of the insulating layer 127 overlaps with the upper surface of the conductive layer 111R, and the other end of the insulating layer 127 overlaps with the upper surface of the conductive layer 111G. With this structure, the end of the insulating layer 127 can be formed on the generally flat region of the EL layer 113R and EL layer 113G. Therefore, it becomes relatively easy to form the tapered shape of the insulating layer 127, insulating layer 125, and mask layer 118. In addition, peeling of the conductive layer 111R, conductive layer 111G, conductive layer 112R, conductive layer 112G, EL layer 113R, and EL layer 113G can be suppressed. On the other hand, the smaller the overlap between the upper surface of the pixel electrode and the insulating layer 127, the wider the light-emitting region of the light-emitting element becomes, and the higher the aperture ratio can be, which is preferable. 【0227】 As described above, in each configuration shown in Figures 5 to 8, by providing insulating layer 127, insulating layer 125, mask layer 118R, and mask layer 118G, the common layer 114 and common electrode 115 can be formed with high coverage from the generally flat region of EL layer 113R to the generally flat region of EL layer 113G. This suppresses the formation of divided areas in the common layer 114 and common electrode 115, as well as areas with locally thin film thickness. Therefore, it is possible to suppress connection failures caused by divided areas and increases in electrical resistance caused by locally thin film thickness in the common layer 114 and common electrode 115 between the light-emitting elements 130. As a result, the display device 100 can be a display device with high display quality. 【0228】 Figures 9A and 9B show modified versions of the configuration shown in Figure 5A. Figure 9A shows an example where the side surface of the insulating layer 105, specifically the side surface of the insulating layer 105 at the boundary between the region overlapping with the conductive layer 111 and the region not overlapping (the part enclosed by the dashed line in Figure 9A), is vertical. Figure 9B shows an example where the upper surface of the insulating layer 127 has a concave shape in cross-sectional view, with a depression in the center and its vicinity, i.e., a concave curved surface. Furthermore, by having a concave curved surface in the central part of the insulating layer 127 as shown in Figure 9B, the stress on the insulating layer 127 can be relieved. More specifically, by providing a configuration in which the insulating layer 127 has a concave curved surface in the center, local stress generated at the edges of the insulating layer 127 can be alleviated, thereby suppressing one or more of the following: delamination between the EL layer 113R and EL layer 113G and the mask layer 118R and mask layer 118G; delamination between the mask layer 118R and mask layer 118G and the insulating layer 125; and delamination between the insulating layer 125 and the insulating layer 127. 【0229】 Furthermore, to create a configuration in which the insulating layer 127 has a concave curved surface in the center, as shown in Figure 9B, exposure can be performed using a multi-gradation mask, typically a halftone mask or graytone mask. A multi-gradation mask is an exposure mask that allows for three exposure levels: an exposed area, an intermediate exposed area, and an unexposed area, resulting in transmitted light of multiple intensities. It is possible to form an insulating layer 127 with multiple (typically two) thickness regions using a single photomask (one exposure and development process). Alternatively, to create a configuration in which the insulating layer 127 has a concave curved surface in the center, the line width of the mask located on the concave curved surface can be made smaller than the line width of the exposed area, thereby forming an insulating layer 127 with multiple thickness regions. 【0230】 The method for forming the structure having a concave curved surface in the center of the insulating layer 127 is not limited to the above. For example, two photomasks may be used to separately produce the exposed portion and the intermediate 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 should be 10 cP or less, preferably 1 cP or more and 5 cP or less. 【0231】 Although not shown in Figure 9B, the concave curved surface in the center 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 center of the insulating layer 127 shown in Figure 9B, and the surface of the insulating layer 125 is exposed. In this configuration, the shape of the insulating layer 127 should be such that the common layer 114 and the common electrode 115 cover the insulating layer 127. 【0232】 [Configuration Example 2] Figure 10 shows a modified configuration of the one shown in Figure 2A, where the edge of the mask layer 118R is aligned with, or approximately aligned with, the edge of the conductive layer 112R, as well as the edge of the EL layer 113R. In other words, Figure 10 shows an example where the edge of the conductive layer 112R is aligned with, 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 with, 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 with, or approximately aligned with, the edge of the conductive layer 112B, as well as the edge of the EL layer 113B. In other words, in the example shown in Figure 10, the edge of the conductive layer 112G is aligned with, or approximately aligned with, the edge of the EL layer 113G, and the edge of the conductive layer 112B is aligned with, or approximately aligned with, the edge of the EL layer 113B. Furthermore, in the example shown in Figure 10, the insulating layer 125 has regions that are in contact with the sides of the EL layer 113R, EL layer 113G, and EL layer 113B, as well as the sides of the conductive layer 112R, conductive layer 112G, and conductive layer 112B. 【0233】 Figure 11A is an enlarged cross-sectional view of the insulating layer 127 and its surrounding region between the EL layer 113R and the EL layer 113G in the configuration shown in Figure 10, and is a modified example of the configuration shown in Figure 5A. In the example shown in Figure 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】 Figures 11B, 12A, 12B, 13A, and 13B are modified examples of the configurations shown in Figures 6A, 7A, 8A, 9A, and 9B, respectively, and are examples of applying the configuration shown in Figure 10. 【0235】 [Configuration Example 3] Figure 14 shows a modified configuration of the one shown in Figure 2A, illustrating an example in which a tandem structure (a structure having multiple light-emitting units) is applied to the light-emitting element 130. Each light-emitting unit has at least one light-emitting layer. It is preferable to provide a charge-generating layer between each light-emitting unit. 【0236】 Figure 14 shows an example configuration in which a two-stage tandem structure, in which two light-emitting units are stacked, is applied to the light-emitting element 130. In Figure 14, the dashed line within the EL layer 113 indicates the charge generation layer. In subsequent figures as well, the charge generation layer of the EL layer 113 may also be shown with a dashed line. 【0237】 In the example shown in Figure 14, the EL layer 113 has a first light-emitting unit below the charge generation layer and a second light-emitting unit above the charge generation layer. By applying a tandem structure to the light-emitting element 130, the current efficiency related to light emission can be increased, thereby increasing the luminous efficiency of the light-emitting element 130. Alternatively, the current density flowing through the light-emitting element 130 can be reduced at the same luminous brightness, thereby reducing the power consumption of the display device 100 having the light-emitting element 130. Furthermore, by applying a tandem structure to the light-emitting element 130, the reliability of the light-emitting element 130 can be increased. Note that a tandem structure of three or more stages 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 can be configured in which 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 from bottom to top. 【0238】 As described above, EL layer 113R, EL layer 113G, and EL layer 113B each have at least an emissive layer. For example, the first emissive unit and the second emissive unit of EL layer 113R each have an emissive layer that emits red light. The first emissive unit and the second emissive unit of EL layer 113G each have an emissive layer that emits green light. Furthermore, the first emissive unit and the second emissive unit of EL layer 113B each have an emissive layer that emits blue light. 【0239】 Furthermore, each light-emitting unit of the EL layer 113R, EL layer 113G, and EL layer 113B may each have one or more of the following: 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】 In the pixel 108 shown in Figure 14, for example, if the pixel electrode of the light-emitting element 130 functions as the anode and the common electrode 115 functions as the cathode, the first light-emitting unit of the EL layer 113R, EL layer 113G, and 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 of the EL layer 113 can be configured, for example, by stacking 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, in that order from bottom to top. Also, the second light-emitting unit of the EL layer 113R, EL layer 113G, and 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 such that, for example, a third functional layer having a hole transport layer, a light-emitting layer, and a fourth functional layer having an electron transport layer are stacked from bottom to top. 【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, they may have a hole-blocking layer between the electron transport layer and the light-emitting layer. Furthermore, the second light-emitting unit may have an electron injection layer on the electron transport layer. Note that the first functional layer may have either a hole injection layer or a hole transport layer, but not the other. 【0242】 Furthermore, for example, if 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 of EL layer 113R, EL layer 113G, and 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. In other words, the first light-emitting unit of EL layer 113 can be configured such that, 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 are stacked. Also, the second light-emitting unit of EL layer 113R, EL layer 113G, and 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 such that, for example, a third functional layer having an electron transport layer, a light-emitting layer, and a fourth functional layer having a hole transport layer are stacked from bottom to top. 【0243】 Here, the first light-emitting unit and the second light-emitting unit may have a hole-blocking layer between the electron-transport layer and the light-emitting layer. Alternatively, they may have an electron-blocking layer between the hole-transport layer and the light-emitting layer. Furthermore, the second light-emitting unit may have a hole-injection layer on top of the hole-transport layer. The first functional layer may have either an electron-injection layer or an electron-transport layer, but not the other. 【0244】 Furthermore, the first light-emitting unit does not need to have a second functional layer, regardless of whether the pixel electrode of the light-emitting element 130 functions as an anode or a cathode. In addition, the second light-emitting unit does not need to have at least one of the third functional layer or the fourth functional layer. 【0245】 The second light-emitting unit preferably has a light-emitting layer and a carrier transport layer on the light-emitting layer. Alternatively, the second light-emitting unit preferably has a light-emitting layer and a carrier block layer on the light-emitting layer. Alternatively, the second light-emitting unit preferably has a light-emitting layer, a carrier block layer on the light-emitting layer, and a carrier transport layer on the carrier block layer. Since the surface of the second light-emitting unit is exposed during the manufacturing process of the display device, by providing one or both of the carrier transport layer and the carrier block layer on the light-emitting layer, it is possible to suppress the exposure of the light-emitting layer to the outermost surface and reduce the damage to the light-emitting layer. This can improve the reliability of the light-emitting element. If there are three or more light-emitting units, it is preferable that the uppermost light-emitting unit has a light-emitting layer and one or both of the carrier transport layer and the carrier block layer on the light-emitting layer. 【0246】 As described above, the light-emitting element 130 can be in a tandem structure. For a detailed configuration of the tandem light-emitting element 130, refer to Embodiment 2. Furthermore, whether the light-emitting element 130 is in a single structure or a tandem structure, the configuration and materials of the light-emitting element 130 can be found in Embodiment 5. 【0247】 Figure 15A is an enlarged cross-sectional view of the insulating layer 127 between the EL layer 113R and the EL layer 113G and its surrounding region in the configuration shown in Figure 14, and is a modified example of the configuration shown in Figure 5A. 【0248】 In the example shown in Figure 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 also 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. Here, in the EL layer 113R shown in Figure 14, the layer indicated by the dashed line corresponds to the charge generation layer 113R2, and in the EL layer 113G, the layer indicated by the dashed line 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 units 113R1 and 113G1 can be the first light-emitting units described in Figure 14, and the light-emitting units 113R3 and 113G3 can be the second light-emitting units described in Figure 14. 【0250】 Figures 15B, 16A, 16B, and 17A are modified versions of the configurations shown in Figures 6A, 7A, 8A, and 9B, respectively, and are examples of applying the configuration shown in Figure 14. Figure 17B is a modified version of the configuration shown in Figure 15A, showing an example in which the upper surface of the insulating layer 127 has a flat portion in cross-sectional view. 【0251】 Figure 18A is a cross-sectional view showing an example of the configuration of region 141 and connection portion 140. In region 141, a conductive layer 109 is provided on the insulating layer 101, and an insulating layer 103 is provided on the insulating layer 101 and on the conductive layer 109. The conductive layer 109 can be formed using the same process as the conductive layer 102 shown in Figure 2A, and can have the same material as the conductive layer 102. 【0252】 Region 141 is provided with an EL layer 113R on the insulating layer 105, a mask layer 118R on the insulating layer 105 and on the EL layer 113R, an insulating layer 125 on the mask layer 118R, an insulating layer 127 on the insulating layer 125, a common layer 114 on the insulating layer 127, 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. In region 141, the mask layer 118R is provided, for example, to cover the edge of the EL layer 113R. Depending on the manufacturing process of the display device 100, for example, an EL layer 113G or an EL layer 113B may be provided in region 141 instead of the EL layer 113R. Also, a mask layer 118G or a mask layer 118B may be provided in region 141 instead of the mask layer 118R. 【0253】 The EL layer 113R provided in region 141 is not electrically connected to the common electrode 115. Therefore, the EL layer 113R provided in region 141 can be configured so that no voltage is applied to it, and thus the EL layer 113R provided in region 141 can be configured so that it does not emit light. 【0254】 In a display device configured such that an EL layer 113R and a mask layer 118R are provided in region 141, as will be described in detail later, it is possible to suppress the removal of a portion of the insulating layer 105, insulating layer 104, and insulating layer 103 by etching or the like during the manufacturing process of the display device, thereby preventing the exposure of the conductive layer 109. This prevents the conductive layer 109 from unintentionally coming into contact with other electrodes or layers. For example, it is possible to suppress a short circuit between the conductive layer 109 and the common electrode 115. As a result, the display device 100 can be a highly reliable display device. Furthermore, the display device 100 can be manufactured using 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 sides 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 the edge of the conductive layer 112C, and the insulating layer 125, insulating layer 127, common layer 114, common electrode 115, and protective layer 131 are laminated on the mask layer 118R in this order. If a mask layer 118G or mask layer 118B is provided in region 141 instead of mask layer 118R, then a mask layer 118G or mask layer 118B is also provided in the connection portion 140 instead of mask layer 118R. 【0256】 In the connection part 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). Thus, for example, by supplying a power potential to the FPC, the power potential can be supplied to the common electrode 115 through the conductive layer 111C and the conductive layer 112C. 【0257】 Here, when the electrical resistance in the thickness direction of the common layer 114 is small enough to be ignored, even when the common layer 114 is provided between the conductive layer 112C and the common electrode 115, conduction 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 part 107 but also in the region 141 and the connection part 140, the common layer 114 can be formed without using a metal mask including, for example, a mask for defining a film formation area (also referred to as an area mask or a rough metal mask, etc., distinguished from a fine metal mask). Therefore, 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, and shows an example in which the common layer 114 is not provided in the connection part 140. In the example shown in FIG. 18B, the conductive layer 112C and the common electrode 115 can be in contact with each other. Thereby, the electrical resistance between the conductive layer 112C and the common electrode 115 can be reduced. In FIG. 18B, in the region 141, the common layer 114 is provided in the region overlapping the EL layer 113R and not provided in the region not overlapping the EL layer 113R, but the present invention is not limited to this. For example, in the region 141, the common layer 114 may not be provided in the region overlapping the EL layer 113R, or the common layer 114 may be provided in the region not overlapping the EL layer 113R. 【0259】 FIG. 18C and FIG. 18D are modified examples of the configurations shown in FIGS. 18A and 18B, respectively, and show an example in which the conductive layer 112C is provided not only in the connection portion 140 but also in the region 141. In the examples shown in FIGS. 18C and 18D, in the region 141, the conductive layer 112C is provided on the insulating layer 105, the EL layer 113R is provided on the conductive layer 112C, and the mask layer 118R is provided on the conductive layer 112C and on the EL layer 113R. Further, in the connection portion 140, the mask layer 118R is provided on the conductive layer 112C. 【0260】 FIG. 18E and FIG. 18F are modified examples 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 is a modified example of the configuration shown in FIG. 2A, and shows an example in which the sub-pixel 110R has the coloring layer 132R, the sub-pixel 110G has the coloring layer 132G, and the sub-pixel 110B has the coloring layer 132B. 【0262】 As shown in FIG. 19A, the coloring layer 132R, the coloring layer 132G, and the coloring layer 132B can be provided on the protective layer 131. In this case, the protective layer 131 is preferably flattened, but it does not have to be flattened. 【0263】 In the example shown in FIG. 19A, the light-emitting elements 130 included in the sub-pixel 110R, the light-emitting elements 130 included in the sub-pixel 110G, and the light-emitting elements 130 included in the sub-pixel 110B can all emit light of the same color, for example, white light. Even in this case, for example, by the coloring layer 132R transmitting red light, the coloring layer 132G transmitting green light, and the coloring layer 132B transmitting blue light, the display device 100 having the configuration shown in FIG. 19A can perform full-color display. Note that the coloring layer 132R, the coloring layer 132G, or the coloring layer 132B may transmit light such as cyan, magenta, yellow, white, or infrared. Further, the light-emitting element 130 may emit, for example, infrared light. 【0264】 The display device 100 having the configuration shown in Figure 19A does not require the EL layer 113 to be manufactured separately for each color, thus simplifying the manufacturing process of the display device 100. Therefore, the manufacturing cost of the display device 100 can be reduced, making the display device 100 a low-cost display device. 【0265】 The adjacent colored layers 132 have overlapping regions on the insulating layer 127. For example, in the cross-section shown in Figure 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 suppresses light leakage from the light-emitting element 130 to the adjacent sub-pixel 110. Therefore, for example, light emitted from the light-emitting element 130 provided in the sub-pixel 110G can be prevented from incident on the colored layer 132R and the colored layer 132B. Consequently, the display device 100 can be a display device with high display quality. 【0266】 Figure 19B is a magnified cross-sectional view of the insulating layer 127 and its surrounding region between the two EL layers 113 shown in Figure 19A. In Figure 19B, conductive layers 112R and 112G are shown as conductive layers 112. The shapes of the mask layer 118, insulating layer 125, and insulating layer 127 shown in Figure 19B are the same as those in Figure 5A. 【0267】 As shown in Figures 19A and 19B, the film thicknesses of the conductive layer 112R, conductive layer 112G, and conductive layer 112B can be different. For example, it is preferable to set the film thickness in accordance with the optical path length that enhances the light of the color transmitted by the colored layer 132. For example, if the colored layer 132R transmits red light, it is preferable to set the film thickness of the conductive layer 112R to enhance red light; if the colored layer 132G transmits green light, it is preferable to set the film thickness of the conductive layer 112G to enhance green light; and if the colored layer 132B transmits blue light, it is preferable to set the film thickness of the conductive layer 112B to enhance blue light. This makes it possible to realize a microcavity structure and improve the color purity of the light emitted from the sub-pixel 110. Note that even in the configuration shown in Figure 2A, for example, the film thicknesses of the conductive layer 112R, conductive layer 112G, and conductive layer 112B can be different. In this case, even if the film thicknesses of EL layer 113R, EL layer 113G, and EL layer 113B are all the same, a microcavity structure can be realized. 【0268】 In Figure 19B, the light-emitting element 130 is shown as a single structure, but it may also be a tandem structure. Figure 20A shows an example in which the EL layer 113 has 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 Figure 20A has a two-stage tandem structure. By applying a tandem structure to the light-emitting element 130, the current efficiency related to light emission can be increased, and thus the luminous efficiency of the light-emitting element 130 can be increased. Alternatively, at the same luminous brightness, the current density flowing through the light-emitting element 130 can be reduced, thereby reducing the power consumption of the display device 100 having the light-emitting element 130. Furthermore, by applying a tandem structure to the light-emitting element 130, the reliability of the light-emitting element 130 can be increased. 【0269】 The light-emitting units 113a1 and 113c1 each have at least one light-emitting layer. The color of the light emitted by light-emitting unit 113a1 and the color of the light emitted by light-emitting unit 113c1 can be made different. 【0270】 In this specification, the light emitted by the light-emitting layer of a light-emitting unit is referred to as "light emitted by the light-emitting unit." 【0271】 The color of the light emitted from the light-emitting layer of light-emitting unit 113a1 and the color of the light emitted from the light-emitting layer of light-emitting unit 113c1 can be, for example, complementary colors. For example, one of the light-emitting units 113a1 or 113c1 can emit blue light, and the other can emit yellow light. For example, one of the light-emitting units 113a1 or 113c1 can emit blue light, and the other can emit red and green light. For example, if 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, each light-emitting unit 113a1 and light-emitting unit 113c1 may have one or more of the following in addition to the light-emitting layer: 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 other words, each light-emitting unit 113a1 and light-emitting unit 113c1 may have a functional layer. The same configuration can be used for light-emitting units other than light-emitting units 113a1 and 113c1. 【0273】 For example, if the pixel electrode of the light-emitting element 130 functions as the anode and the common electrode 115 functions as the cathode, the light-emitting unit 113a1 can be configured such that, 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 are stacked. Alternatively, the light-emitting unit 113c1 may have a hole transport layer, a light-emitting layer, and an electron transport layer in this order. In other words, the light-emitting unit 113c1 can be configured such that, 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 are stacked. 【0274】 Here, the light-emitting units 113a1 and 113c1 may have an electron-blocking layer between the hole transport layer and the light-emitting layer. Alternatively, they may have a hole-blocking layer 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. Note that the first functional layer may have either a hole injection layer or a hole transport layer, but not the other. 【0275】 Furthermore, for example, if 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 such that, 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 are stacked. The light-emitting unit 113c1 may also have an electron transport layer, a light-emitting layer, and a hole transport layer in this order. In other words, the light-emitting unit 113c1 can be configured such that, 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 are stacked. 【0276】 Here, the light-emitting units 113a1 and 113c1 may have a hole-blocking layer between the electron-transport layer and the light-emitting layer. Alternatively, they may have an electron-blocking layer between the hole-transport layer and the light-emitting layer. Furthermore, the light-emitting unit 113c1 may have a hole-injection layer between the hole-transport layer and the common electrode 115. The first functional layer may have either an electron-injection layer or an electron-transport layer, but not the other. 【0277】 Furthermore, the light-emitting unit 113a1 does not need to have a second functional layer, regardless of whether the pixel electrode of the light-emitting element 130 functions as an anode or a cathode. In addition, the light-emitting unit 113c1 does not need to have at least one of a third functional layer or a fourth functional layer. 【0278】 The charge generation layer 113b1 has at least a charge generation region. The charge generation layer 113b1 has the function of injecting electrons into one of the light-emitting units 113a1 or 113c1 and injecting holes into the other of the light-emitting units 113a1 or 113c1 when a voltage is applied between the pixel electrode and the common electrode 115 of the light-emitting element 130. 【0279】 Figure 20B shows an example in which the EL layer 113 has 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 Figure 20B has a three-stage tandem structure. By increasing the number of stages in the tandem structure, the current efficiency related to the light emission of the light-emitting element 130 can be suitably increased, and thus the luminous efficiency of the light-emitting element 130 can be suitably increased. Alternatively, the current density flowing through the light-emitting element 130 can be suitably reduced at the same luminous brightness, and thus the power consumption of the display device 100 having the light-emitting element 130 can be suitably reduced. Furthermore, the reliability of the light-emitting element 130 can be suitably increased. Note that the light-emitting element 130 may have a tandem structure of four or more stages. 【0280】 The light-emitting units 113a2, 113c2, and 113e each have at least one light-emitting layer. The color of the light emitted by at least one of the light-emitting units 113a2, 113c2, and 113e can be different from the color of the light emitted by the other light-emitting units. For example, the color of the light emitted by at least one of the light-emitting units 113a2, 113c2, and 113e can be the complementary color of the light emitted by the other light-emitting units. 【0281】 For example, the light-emitting unit 113a2 and the light-emitting unit 113e emit blue light, and the light-emitting unit 113c2 can emit yellow, yellow-green, or green light. For example, the light-emitting unit 113a2 and the light-emitting unit 113e emit blue light, and the light-emitting unit 113c2 can emit red, green, and yellow-green light. As described above, 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. When a voltage is applied between the pixel electrode of the light-emitting element 130 and the common electrode 115, the charge generation layer 113b2 has a function of injecting electrons into one of the light-emitting unit 113a2 or the light-emitting unit 113c2 and injecting holes into the other of the light-emitting unit 113a2 or the light-emitting unit 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 unit 113c2 or the light-emitting unit 113e and injecting holes into the other of the light-emitting unit 113c2 or the light-emitting unit 113e. 【0283】 FIG. 21A is a modified example of the configuration shown in FIG. 10, and shows an example in which the sub-pixel 110R has a coloring layer 132R, the sub-pixel 110G has a coloring layer 132G, and the sub-pixel 110B has a coloring layer 132B. That is, 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 region. Note that FIG. 21B shows the conductive layers 112R and 112G as the conductive layer 112. Also, the shapes of the mask layer 118, the insulating layer 125, the insulating layer 127, etc. shown in FIG. 21B are the same as those in FIG. 11A. 【0285】 In one embodiment of the present invention, the display device has an EL layer arranged in an island shape for each light-emitting element, thereby suppressing the generation of lateral leakage current between subpixels. This suppresses crosstalk caused by unintended light emission, enabling the realization of a display device with extremely high contrast. Furthermore, by providing an insulating layer with a tapered shape at its edges between adjacent island-shaped EL layers, it is possible to suppress the occurrence of step breaks during the formation of the common electrode and to suppress the formation of locally thin areas in the common electrode. This suppresses connection failures caused by the separated areas and increases in electrical resistance caused by locally thin areas in the common layer and common electrode. As a result, the display device in one embodiment of the present invention can achieve both high resolution and high display quality. 【0286】 Next, the light-emitting region of a display device according to one embodiment of the present invention will be described with reference to the drawings. 【0287】 [Configuration Example 5] Figure 22A shows a modified version of the configuration shown in Figure 19A. In Figure 22A, for example, the microcavity structure described earlier is omitted, and an enlarged cross-sectional view of the vicinity of sub-pixels 110R and 110G shown in Figure 19A is displayed. Figure 22B is a reference cross-sectional view illustrating the light-emitting area of ​​the display device. In Figures 22A and 22B, the colored layer 132 and plug 106, etc., are omitted. 【0288】 In Figure 22A, in addition to the configuration described in Figure 19A, regions 180 and 182 are illustrated to illustrate the light-emitting regions of the display device. Region 180 functions as a light-emitting region of the display device, and region 182 functions as a non-light-emitting region of the display device. 【0289】 In the light-emitting region of the display device, an EL layer is provided between a pair of electrodes (also referred to as between the upper and lower electrodes, or between the anode and cathode). This EL layer includes island-shaped EL layers 113 as well as a common layer 114. In Figure 22A, the EL layer 113 is exemplified as having 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 Figure 22A, the common layer 114 functions as an electron injection layer. 【0290】 Figure 22B is a cross-sectional view showing one embodiment of a display device. The display device shown in Figure 22B includes an insulating layer 105, a conductive layer 111R on the insulating layer 105, a conductive layer 111G on the insulating layer 105, a conductive layer 112R on the conductive layer 111R, a conductive layer 112G on 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 on the EL layer 113, a common electrode 115 on the common layer 114, and a protective layer 131 on the common electrode 115. 【0291】 In the light-emitting region of the display device shown in Figure 22B, an EL layer 113 and a common layer 114 are provided as an EL layer between a pair of electrodes. Unlike in Figure 22A, the EL layer 113 shown in Figure 22B is a continuous film shared by multiple light-emitting elements. In Figure 22B, the EL layer 113 is exemplified as having 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 Figure 22B, the common layer 114 functions as an electron injection layer. 【0292】 In Figure 22B, the insulating layer 127b is provided so as to cover the side surface of the conductive layer 111R, the side surface of the conductive layer 111G, the side surface and part of the top surface of the conductive layer 112R, and the side surface and part of the top surface of the conductive layer 112G. In this way, the insulating layer 127b functions as a structure (also called a dam) that covers the side surface and part of the top surface of the conductive layer. That is, the insulating layer 127b is provided so as to have regions that are in contact with the conductive layers 111R, 111G, 112R, and 112G. 【0293】 Figure 22B illustrates regions 184 and 186. Region 184 functions as an emitting region of the display device, and region 186 functions as a non-emitting region of the display device. 【0294】 As shown in Figure 22A, in a display device according to one embodiment of the present invention, the EL layer 113 (here, 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) is provided in an island-like manner for each light-emitting element, thereby suppressing the generation of lateral leakage current between subpixels. In particular, by providing the hole injection layer 113-1 of the EL layer 113 in an island-like manner, the lateral leakage current between subpixels can be suitably reduced. Since the hole injection layer 113-1 is a layer with higher conductivity in the EL layer 113 compared to other layers, it is preferable that at least the hole injection layer 113-1 is separated between adjacent subpixels, as shown in Figure 22A. 【0295】 Furthermore, in Figure 22A, in the region 180 that functions as a light-emitting region, it is preferable that the difference between the distance between the pair of electrodes in the central part of the EL layer (EL layer 113 and common layer 114) (indicated as D1) and the distance between the pair of electrodes at the edges of the EL layer (EL layer 113 and common layer 114) (indicated as D2) is small. More specifically, the distance between the pair of electrodes at the edges of the EL layer (D2) is preferably less than ±10% and more preferably less than ±3% of the distance between the pair of electrodes at the central part of the EL layer (D1). By reducing or eliminating the difference between the distance between the pair of electrodes at the central part of the EL layer (D1) and the distance between the pair of electrodes at the edges of the EL layer (D2), uniform light emission can be obtained in the light-emitting region. 【0296】 On the other hand, as shown in Figure 22B, when the EL layer 113 is provided in common between adjacent subpixels, particularly when the hole injection layer 113-1 is used in common between adjacent subpixels, there is a possibility that part or all of the region 186, which functions as a non-emitting region, may emit light. In other words, there is a possibility that a lateral leakage current will occur between the subpixels. Also, in Figure 22B, in the region 184 that functions as an emitting region, the difference between the distance between a pair of electrodes in the central part of the EL layer (EL layer 113 and common layer 114) (shown as D3) and the distance between a pair of electrodes at the edge of the EL layer (EL layer 113 and common layer 114) (shown as D4) is greater than the difference between D1 and D2 mentioned above. 【0297】 In Figure 22B, the distance between the pair of electrodes in region 186, which functions as a non-emitting region (indicated as D5), is greater than the distance between the pair of electrodes at the edge of the EL layer (D4). The distance between the pair of electrodes in region 186 (D5) is the sum of the film thickness of the EL layer 113, the film thickness of the common layer 114, and the film thickness at the edge of the insulating layer 127b. For example, if a part of region 186, which functions as a non-emitting region, emits light, the distance between the pair of electrodes in region 186 (D5) resonates with the light, and therefore differs from the resonance distance of the light in region 184, which functions as an emitting region. Thus, when region 186 emits light, the resonance distance of the light changes between region 186 and region 184, resulting in differences in luminance, chromaticity, and emission direction between region 186 and region 184. Furthermore, when light emission from region 184, which functions as an emitting region, and region 186, which functions as a non-emitting region, is mixed, the emission spectrum may become broad, or the emission spectrum may have multiple peaks. On the other hand, in the configuration shown in Figure 22A, since emission from the non-emitting region is suppressed, it is possible to prevent the emission spectrum from becoming broad or having a shape with multiple peaks. 【0298】 Furthermore, in display devices, high brightness (for example, 10,000 cd / m²) 2 ) and low brightness (for example, 100 cd / m²) 2 A configuration in which the chromaticity does not change is preferable. For this reason, the structure shown in Figure 22A is preferable to the structure shown in Figure 22B. 【0299】 Figure 23 shows a modified version of the configuration shown in Figure 21A. In Figure 23, for example, the microcavity structure described earlier is omitted, and an enlarged cross-sectional view of the vicinity of sub-pixels 110R and 110G, as shown in Figure 21A, is shown. In other words, Figure 23 is an example of combining the configuration shown in Figure 21A and the configuration shown in Figure 22A. 【0300】 [Example of manufacturing method 1] In the following section, examples of methods for manufacturing a display device 100 having the configuration shown in Figure 2A and the configuration shown in Figure 18A will be explained with reference to the drawings. 【0301】 Thin films (insulating films, semiconductor films, conductive films, etc.) that constitute display devices can be formed using sputtering, chemical vapor deposition (CVD), vacuum deposition, pulsed laser deposition (PLD), or ALD. Examples of CVD methods include plasma-enhanced CVD (PECVD) and thermal CVD. One type of thermal CVD method is metal-organic chemical vapor deposition (MOCVD). 【0302】 Furthermore, thin films (insulating films, semiconductor films, conductive films, etc.) that constitute the display device can be formed by wet film deposition methods such as spin coating, dip coating, spray coating, inkjet printing, 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 or inkjet can be used to fabricate light-emitting elements. Examples of 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). The EL layer, in particular, can be formed by vapor deposition (e.g., vacuum deposition), coating methods (dip coating, die coating, bar coating, spin coating, or spray coating, etc.), and printing methods (inkjet, screen printing, offset printing, flexographic printing, gravure, or microcontact printing, etc.). 【0304】 Furthermore, when processing the thin film that constitutes the display device, it can be processed using, for example, photolithography. Alternatively, the thin film may be processed by nanoimprint lithography, sandblasting, or lift-off lithography. In addition, island-shaped thin films may be directly formed by a film deposition method using a shielding mask such as a metal mask. 【0305】 There are two main methods of photolithography. One method involves forming a resist mask on the thin film to be processed, then processing the thin film, for example by etching, and removing the resist mask. The other method involves forming a photosensitive thin film, then exposing and developing it to process the thin film into the desired shape. 【0306】 In photolithography, exposure can use, for example, i-line (wavelength 365 nm), g-line (wavelength 436 nm), h-line (wavelength 405 nm), or a mixture thereof. Other options include ultraviolet light, KrF laser light, or ArF laser light. Exposure may also be performed using immersion lithography. Furthermore, exposure may be performed using extreme ultraviolet (EUV) light or X-rays. An electron beam can also be used instead of light for exposure. Using extreme ultraviolet light, X-rays, or an electron beam is preferable because it allows for extremely fine processing. Note that a photomask is not required when exposure is performed by scanning a beam such as an electron beam. 【0307】 For etching thin films, dry etching, wet etching, or sandblasting methods can be used. 【0308】 To manufacture a display device 100 having the configuration shown in Figure 2A and the configuration shown in Figure 18A, first, an insulating layer 101 is formed on a substrate (not shown) as shown in Figure 24A. Next, a conductive layer 102 and a conductive layer 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. Next, an insulating layer 104 is formed on the insulating layer 103, and an insulating layer 105 is formed on the insulating layer 104. 【0309】 As the substrate, a substrate with sufficient heat resistance to withstand subsequent heat treatment can be used. When using an insulating substrate, glass substrates, quartz substrates, sapphire substrates, ceramic substrates, or organic resin substrates can be used. In addition, semiconductor substrates such as single-crystal semiconductor substrates, polycrystalline semiconductor substrates, compound semiconductor substrates such as silicon-germanium, or SOI substrates made from silicon or silicon carbide can be used. 【0310】 Note that Figure 24A shows the cross-sectional view between A1 and A2 and the cross-sectional view between B1 and B2 side by side. The same applies to the following figures that describe examples of how to manufacture a display device. 【0311】 Next, as shown in Figure 24A, openings reaching the conductive layer 102 are formed in the insulating layer 105, insulating layer 104, and insulating layer 103. Subsequently, a plug 106 is formed to fill these openings. 【0312】 Next, as shown in Figure 24A, a conductive film 111f, which will later become conductive layers 111R, 111G, 111B, and 111C, is formed on the plug 106 and the insulating layer 105. For example, sputtering or vacuum deposition can be used to form the conductive film 111f. In addition, a metallic material can be used as the conductive film 111f. 【0313】 The conductive film 111f can have a three-layer laminated structure, consisting of a film that will later become conductive layer 111a, a film that will later become conductive layer 111b, and a film that will later become conductive layer 111c, in that order from bottom to top. Alternatively, the conductive film 111f can have a two-layer laminated structure, consisting of a film that will later become conductive layer 111a, a film that will later become conductive layer 111b, and a film that will later become conductive layer 111c, in that order from bottom to top. For example, titanium can be used as the film that will become conductive layer 111a, aluminum can be used as the film that will become conductive layer 111b, and titanium can be used as the film that will become conductive layer 111c. Alternatively, the conductive film 111f can have a single-layer structure. 【0314】 Next, as shown in Figure 24B, the conductive film 111f is processed using, 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 metallic material is used as the conductive film 111f, the conductive film 111f can be removed by, for example, dry etching. Here, for example, when a portion of the conductive film 111f is removed by dry etching, a recess may be formed in the 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 be arranged in a three-layer laminated structure consisting of conductive layer 111a, conductive layer 111b on conductive layer 111a, and conductive layer 111c on conductive layer 111b, as shown in Figures 2B1, 2B2, and 4C. Alternatively, the conductive layers 111R, 111G, 111B, and 111C can be arranged in a two-layer laminated structure consisting of conductive layer 111a and conductive layer 111b on conductive layer 111a, as shown in Figures 3A, 3B, and 4B. Furthermore, the conductive layers 111R, 111G, 111B, and 111C can be arranged in a single-layer structure as shown in Figure 4A. 【0316】 Next, as shown in Figure 24C, conductive films 112f, which will later become conductive layers 112R, 112G, 112B, and 112C, are formed on conductive layers 111R, 111G, 111B, 111C, and 105, respectively. For the formation of the conductive films 112f, for example, sputtering or vacuum deposition can be used. 【0317】 When forming the conductive layer 112 with the configuration shown in Figures 2B1 and 3A, a conductive oxide can be used as the conductive film 112f. Furthermore, when forming the conductive layer 112 with the configuration shown in Figures 2B2 and 3B, the conductive film 112f can have a two-layer laminated structure consisting of a film that later becomes conductive layer 112a and a film that later becomes conductive layer 112b. For example, a metallic material such as titanium, silver, or a silver-containing alloy can be used as the film that becomes conductive layer 112a, and a conductive oxide can be used as the film that becomes conductive layer 112b. Moreover, when forming the conductive layer 112 with the configuration shown in Figures 4A, 4B, and 4C, the conductive film 112f can have a three-layer laminated structure consisting of a film that later becomes conductive layer 112a, a film that later becomes conductive layer 112b, and a film that later becomes conductive layer 112c. For example, a conductive oxide can be used as the film that forms the conductive layer 112a, silver or a silver-containing alloy can be used as the film that forms the conductive layer 112b, and a conductive oxide can be used as the film that forms the conductive layer 112c. 【0318】 Furthermore, the ALD method can be used to form the conductive film 112f. Here, the conductive film 112f can be an oxide having one or more selected from indium, tin, zinc, gallium, titanium, aluminum, and silicon. In this case, the conductive film 112f can be formed by repeating a cycle in which one cycle consists of introducing a precursor (generally sometimes called a precursor or metal precursor), purging the precursor, introducing an oxidizing agent (generally sometimes called a reactant or nonmetal precursor), and purging the oxidizing agent. Here, when forming an oxide film containing multiple types of metals, such as indium tin oxide, 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, and an oxidizing agent is introduced to form an In-O film. Then, a tin-containing precursor is introduced, the precursor is purged, and an oxidizing agent is introduced to form a Sn-O film. Here, by making the number of cycles for In-O film formation greater than the number of cycles for Sn-O film formation, the number of In atoms in the conductive film 112f can be made greater than the number of Sn atoms. 【0320】 Furthermore, for example, when a zinc oxide film is deposited as the conductive film 112f, a Zn-O film is formed using the procedure described above. Furthermore, for example, when an aluminum zinc oxide film is deposited as the conductive film 112f, a Zn-O film and an Al-O film are formed using the procedure described above. Furthermore, for example, when a titanium oxide film is deposited as the conductive film 112f, a Ti-O film is formed using the procedure described above. Furthermore, for example, when an indium tin oxide film containing silicon is deposited as the conductive film 112f, an In-O film, a Sn-O film, and a Si-O film are formed using the procedure described above. Furthermore, for example, when a zinc oxide film containing gallium is deposited as the conductive film 112f, a Ga-O film and a Zn-O film are formed using the procedure described above. 【0321】 As an indium-containing precursor, for example, triethylindium, trimethylindium, or [1,1,1-trimethyl-N-(trimethylsilyl)amide]-indium can be used. As a tin-containing precursor, for example, tin chloride or tetrakis(dimethylamide)tin can be used. As a zinc-containing precursor, for example, diethylzinc or dimethylzinc can be used. As a gallium-containing precursor, for example, triethylgallium can be used. As a titanium-containing precursor, for example, titanium chloride, tetrakis(dimethylamide)titanium, or tetraisopropyl titanate can be used. As an aluminum-containing precursor, for example, aluminum chloride or trimethylaluminum can be used. As a silicon-containing precursor, for example, trisilylamine, bis(diethylamino)silane, tris(dimethylamino)silane, bis(tert-butylamino)silane, or bis(ethylmethylamino)silane can be used. In addition, as an oxidizing agent, for example, water vapor, oxygen plasma, or ozone gas can be used. 【0322】 Here, for example, the surface of the conductive layer 111 may oxidize after the formation of the conductive layer 111 and before the formation of the conductive film 112f. For example, if the conductive layer 111 is exposed to the atmosphere after its formation, the surface of the conductive layer 111 may oxidize due to oxygen contained in the atmosphere. Here, if a metal whose electrical resistivity increases with 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 result in defects in the manufactured display device, leading to an unreliable display device. 【0323】 Therefore, it is preferable to remove the oxide from the surface of the conductive layer 111 after its formation and before the conductive film 112f is formed. Then, after removing the oxide, it is preferable to form the conductive film 112f without exposing it to the atmosphere. This makes it possible to reduce the electrical resistance at the contact interface between the conductive layer 111 and the conductive layer 112. As a result, defects in the display device 100 are suppressed, and the display device 100 can be made into a highly reliable display device. The oxide on the surface of the conductive layer 111 can be removed, for example, by reverse sputtering. 【0324】 Reverse sputtering is a method of modifying a surface by having ions collide with the surface to be treated, rather than colliding with the sputtering target as in conventional sputtering. One method of colliding ions with 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. Alternatively, an atmosphere containing nitrogen or oxygen may be used instead of a gas atmosphere containing a Group 18 element. The equipment used in reverse sputtering is not limited to sputtering equipment; similar processing can be performed using plasma CVD equipment or dry etching equipment. 【0325】 Next, as shown in Figure 24D, the conductive film 112f is processed using, 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 sides of the conductive layer 111. For example, if the conductive layer 112 has the configuration shown in Figure 2B2, and a metal material is used as the conductive layer 112a and a conductive oxide is used as the conductive layer 112b, a portion of the conductive film that will become conductive layer 112b can be removed by wet etching, and then a portion of the conductive film that will become conductive layer 112a can be removed by dry etching. Alternatively, a portion of the conductive film that will become conductive layer 112a may be removed by wet etching, or a portion of the conductive film that will become conductive layer 112b may be removed by dry etching. 【0326】 Here, when the conductive layer 112 has a laminated structure of conductive layer 112a and conductive layer 112b as shown in Figures 2B2 and 3B, the film that becomes conductive layer 112a, which is included in the conductive film 112f, can be made of a metallic material such as titanium, silver, or an alloy containing silver. The film that becomes conductive layer 112b, which is included in the conductive film 112f, can be made of a conductive oxide such as indium tin oxide. As mentioned above, by using silver or an alloy containing silver as the conductive layer 112a, the reflectivity of the pixel electrode to visible light can be increased. On the other hand, as mentioned above, titanium has better processability by etching than silver, so by using titanium as the film that becomes conductive layer 112a, the film can be easily processed to form the conductive layer 112a. 【0327】 Next, it is preferable to perform a hydrophobic treatment on the conductive layer 112. The hydrophobic treatment can change the surface to be treated from hydrophilic to hydrophobic, or increase the hydrophobicity of the surface to be treated. By performing the hydrophobic treatment on the conductive layer 112, the adhesion between the conductive layer 112 and the EL layer 113 formed in a later step can be improved, and film peeling can be suppressed. However, the hydrophobic treatment is not required. 【0328】 Hydrophobic treatment can be carried out, for example, by fluorine modification of the conductive layer 112. Fluorine modification can be carried out, for example, by treatment with a fluorine-containing gas, heat treatment, or plasma treatment in a fluorine-containing gas atmosphere. As the fluorine-containing gas, for example, fluorine gas can be used, or for example, fluorocarbon gas can be used. As the fluorocarbon gas, for example, lower fluorinated carbon gases such as carbon tetrafluoride (CF4) gas, C4F6 gas, C2F6 gas, C4F8 gas, or C5F8 can be used. In addition, as the fluorine-containing gas, for example, SF6 gas, NF3 gas, or CHF3 gas can be used. Furthermore, 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 made hydrophobic by performing plasma treatment in a gas atmosphere containing a group 18 element such as argon, followed by treatment with a silylation agent. Hexamethyldisilazane (HMDS) or trimethylsilylimidazole (TMSI) can be used as the silylation agent. In addition, the surface of the conductive layer 112 can also be made hydrophobic by performing plasma treatment in a gas atmosphere containing a group 18 element such as argon, followed by treatment with 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, damage can be inflicted on the surface of the conductive layer 112. This makes it easier for methyl groups contained in silylation agents such as HMDS to bond to the surface of the conductive layer 112. It also makes silane coupling by silane coupling agents easier to occur. Thus, 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 with a silylation agent or a silane coupling agent, the surface of the conductive layer 112 can be made hydrophobic. 【0331】 Treatment using a silylation agent or silane coupling agent can be carried out by applying the silylation agent or silane coupling agent using, for example, a spin coating method or a dip method. Alternatively, treatment using a silylation agent or silane coupling agent can be carried out by forming a film containing a silylation agent or a film containing a silane coupling agent on the conductive layer 112, for example, using a gas phase method. In the gas phase method, first, a material containing a silylation agent or a material containing a silane coupling agent is volatilized to introduce the silylation agent or silane coupling agent into the atmosphere. Subsequently, a substrate on which, for example, the conductive layer 112 is formed is placed in this atmosphere. This allows a film containing a silylation agent or silane coupling agent to be formed on the conductive layer 112, thereby hydrophobicizing the surface of the conductive layer 112. 【0332】 Next, as shown in Figure 25A, the 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】 As shown in Figure 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 deposited only in the desired region. By employing a deposition process using an area mask and a processing process using a resist mask, a light-emitting element can be manufactured using a relatively simple process. 【0334】 The EL film 113Rf can be formed, for example, by a vapor deposition method, specifically by a vacuum deposition method. Alternatively, the EL film 113Rf may be formed by methods such as a transfer method, a printing method, an inkjet method, or a coating method. 【0335】 Next, as shown in Figure 25A, a mask film 118Rf, which will later become a mask layer 118R, and a mask film 119Rf, which will later become a mask layer 119R, are formed in order on the EL film 113Rf, the conductive layer 112C, and the insulating layer 105, respectively. 【0336】 In this embodiment, an example is shown in which the mask film is formed with a two-layer structure consisting of mask film 118Rf and mask film 119Rf, but the mask film may also 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, thereby improving the reliability of the light-emitting element. 【0338】 For the mask film 118Rf, a film with high resistance to the processing conditions of the EL film 113Rf is used, specifically a film with a high etching selectivity ratio with the EL film 113Rf. For the mask film 119Rf, a film with a high etching selectivity ratio with the mask film 118Rf is used. 【0339】 Furthermore, the mask films 118Rf and 119Rf are formed at a temperature lower than the heat resistance 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 mask films 118Rf and 119Rf that can be removed by wet etching. By using wet etching, the damage to the EL film 113Rf during processing of mask films 118Rf and 119Rf can be reduced compared to using dry etching. 【0341】 For the formation of the mask films 118Rf and 119Rf, for example, sputtering, ALD (thermal ALD or PEALD), CVD, or vacuum deposition can be used. Alternatively, they may be formed using the wet film formation method described above. 【0342】 Furthermore, it is preferable that the mask film 118Rf, which is formed in contact with the EL film 113Rf, is formed using a 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 vacuum deposition method rather than the sputtering method. 【0343】 For the mask film 118Rf and the mask film 119Rf, one or more types can be used, for example, from among metal films, alloy films, metal oxide films, semiconductor films, organic insulating films, and inorganic insulating films. 【0344】 The mask film 118Rf and the mask film 119Rf can be made of a metallic 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 metallic material. In particular, it is preferable to use a low-melting-point material such as aluminum or silver. It is preferable to use a metallic material capable of shielding ultraviolet rays in one or both of the mask film 118Rf and the mask film 119Rf, as this can suppress the irradiation of the EL film 113Rf with ultraviolet rays and suppress the degradation of the EL film 113Rf. 【0345】 Furthermore, the mask films 118Rf and 119Rf can be made from metal oxides 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 silicon-containing indium tin oxide, respectively. 【0346】 In addition, element M (where M is one or more selected from aluminum, silicon, boron, yttrium, copper, vanadium, beryllium, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, or magnesium) may be used instead of gallium. In particular, it is preferable that M be one or more selected from gallium, aluminum, or yttrium. 【0347】 Furthermore, a film containing a material that has light-shielding properties against light, particularly ultraviolet light, can be used as the mask film. For example, a film that reflects ultraviolet light or a film that absorbs ultraviolet light can be used. Various materials can be used as the light-shielding material, such as metals, insulators, semiconductors, or metalloids that have light-shielding properties against ultraviolet light. However, since part or all of the mask film will be removed in a later process, it is preferable that the film be processable by etching, and in particular, that it has good processability. 【0348】 For example, semiconductor materials such as silicon and germanium are considered to be highly compatible with semiconductor manufacturing processes. Oxides and nitrides of the above semiconductor materials are also included. Nonmetallic (metalloid) materials such as carbon and their compounds are also included. Metals such as titanium, tantalum, tungsten, chromium, and aluminum, as well as alloys containing one or more of these, are also included. Oxides containing the above metals, such as titanium oxide and chromium oxide, and nitrides such as titanium nitride, chromium nitride, and tantalum nitride are also included. 【0349】 By using a mask film containing a material that has light-shielding properties against ultraviolet light, it is possible to suppress the irradiation of the EL layer with ultraviolet light during the exposure process, for example. By suppressing damage to the EL layer from ultraviolet light, the reliability of the light-emitting element can be improved. 【0350】 Furthermore, a film containing a material that has light-shielding properties against ultraviolet rays can be used as the insulating film 125f described later to achieve the same effect. 【0351】 Furthermore, various inorganic insulating films that can be used in the protective layer 131 can be used as the mask films 118Rf and 119Rf, respectively. In particular, oxide insulating films are preferred because they have higher adhesion to the EL film 113Rf compared to nitride insulating films. For example, inorganic insulating materials such as aluminum oxide, hafnium oxide, or silicon oxide can be used as the mask films 118Rf and 119Rf, respectively. For example, aluminum oxide films can be formed as the mask films 118Rf and 119Rf using the ALD method. Using the ALD method is preferred because it reduces damage to the substrate, especially the EL layer. 【0352】 For example, as the mask film 118Rf, an inorganic insulating film formed using the ALD method, such as an aluminum oxide film, can be used, and as the mask film 119Rf, an inorganic film formed using the sputtering method, such as an In-Ga-Zn oxide film, an aluminum film, or a tungsten film, can be used. 【0353】 Furthermore, the same inorganic insulating film can be used for both the mask film 118Rf and the insulating layer 125 that is formed later. For example, an aluminum oxide film formed using the ALD method can be used for both the mask film 118Rf and the insulating layer 125. Here, the same film deposition conditions may be applied to the mask film 118Rf and the insulating layer 125, or different film deposition conditions may be applied to each. For example, by depositing the mask film 118Rf under the same conditions as the insulating layer 125, the mask film 118Rf can be made into 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 mostly or completely removed in a later process, it is preferable that it be easy to process. For this reason, it is preferable to deposit the mask film 118Rf under conditions where the substrate temperature during film deposition is lower than that of the insulating layer 125. 【0354】 Organic materials may be used in one or both of the mask films 118Rf and 119Rf. For example, a material that is soluble in a chemically stable solvent may be used as the organic material. Materials that are soluble in water or alcohol are particularly suitable. When forming such a film, it is preferable to apply the material by a wet deposition method while it is dissolved in a solvent such as water or alcohol, and then perform a heat treatment to evaporate the solvent. At this time, it is preferable to perform the heat treatment under a reduced pressure atmosphere, as this allows the solvent to be removed at a low temperature and in a short time, thereby reducing thermal damage to the EL film 113Rf. 【0355】 Mask films 118Rf and 119Rf may be made of polyvinyl alcohol (PVA), polyvinyl butyral, polyvinylpyrrolidone, polyethylene glycol, polyglycerin, pullulan, water-soluble cellulose, alcohol-soluble polyamide resin, or organic resins such as perfluoropolymers. 【0356】 For example, an organic film (e.g., a PVA film) formed using either a vapor deposition method or the wet film formation method described above can be used as the mask film 118Rf, and an inorganic film (e.g., a silicon nitride film) formed using a sputtering method can be used as the mask film 119Rf. 【0357】 In addition, in one embodiment of the present invention, a portion of the mask film may remain as a mask layer in the display device. 【0358】 Next, as shown in Figure 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), followed by exposure and development. 【0359】 The resist mask 190R may be made using either a positive-type resist material or a negative-type resist material. 【0360】 The resist mask 190R is provided in a position that overlaps with the conductive layer 112R. Preferably, the resist mask 190R is also provided in a position that overlaps with the conductive layer 112C. This helps to suppress damage to the conductive layer 112C during the manufacturing process of the display device. It is not necessary to provide the resist mask 190R on the conductive layer 112C. Furthermore, it is preferable that the resist mask 190R be provided so as to cover from the edge of the EL film 113Rf to the edge of the conductive layer 112C on the EL film 113Rf side, as shown in the cross-sectional view between B1 and B2 in Figure 25A. 【0361】 Next, as shown in Figures 25A and 25B, a portion of the mask film 119Rf is removed using the resist mask 190R to form a mask layer 119R. The mask layer 119R remains on the conductive layer 112R and the conductive layer 112C. After that, the resist mask 190R is removed. Subsequently, the mask layer 119R is used as a mask (also called a hard mask) to remove a portion of the mask film 118Rf to form a mask layer 118R. 【0362】 Mask films 118Rf and 119Rf can be processed by wet etching or dry etching, respectively. It is preferable to process mask films 118Rf and 119Rf by anisotropic etching. 【0363】 By using the wet etching method, the damage to the EL film 113Rf during processing of the mask film 118Rf and mask film 119Rf can be reduced compared to using the dry etching method. When using the wet etching method, it is preferable to use chemical solutions such as a developer, aqueous solution of tetramethylammonium hydroxide (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 during the processing of the mask film 119Rf, there is a wider range of processing method options than when processing the mask film 118Rf. Specifically, when using an oxygen-containing gas as the etching gas during the processing of the mask film 119Rf, the degradation of the EL film 113Rf can be suppressed more effectively than when using an oxygen-containing gas as the etching gas during the processing of the mask film 118Rf. 【0365】 Furthermore, when using a dry etching method for processing the mask film 118Rf, the degradation of the EL film 113Rf can be suppressed by not using an oxygen-containing gas as the etching gas. When using a dry etching method, it is preferable to use a gas containing, for example, CF4, C4F8, SF6, CHF3, Cl2, H2O, BCl3, or a Group 18 element as the etching gas. He can be used as a Group 18 element, for example. 【0366】 For example, when using an aluminum oxide film formed by the ALD method as the mask film 118Rf, a portion of the mask film 118Rf can be removed by dry etching using CHF3 and He, or CHF3, He, and CH4. Also, when using an In-Ga-Zn oxide film formed by the sputtering method as the mask film 119Rf, a portion of the mask film 119Rf can be removed by wet etching using diluted phosphoric acid. Alternatively, a portion of the mask film 119Rf may be removed by dry etching using CH4 and Ar. Alternatively, a portion of the mask film 119Rf can be removed by wet etching using diluted phosphoric acid. Furthermore, when using a tungsten film formed by the sputtering method as the mask film 119Rf, a portion of the mask film 119Rf can be removed by dry etching using SF6, CF4, and O2, or CF4, Cl2, and O2. 【0367】 The resist mask 190R can be removed, for example, by ashing using oxygen plasma. Alternatively, oxygen gas and CF4, C4F8, SF6, CHF3, Cl2, H2O, BCl3, or a group 18 element may be used. He can be used as the group 18 element. Alternatively, the resist mask 190R may be removed by wet etching. In this case, since the mask film 118Rf is located on the outermost surface and the EL film 113Rf is not exposed, damage to the EL film 113Rf can be suppressed during the resist mask 190R removal process. Furthermore, the range of selectable methods for removing the resist mask 190R can be broadened. 【0368】 Next, as shown in Figures 25A and 25B, the EL film 113Rf is processed to form the EL layer 113R. For example, mask layers 119R and 118R are used as masks to remove a portion of the EL film 113Rf and form the EL layer 113R. 【0369】 As a result, as shown in Figure 25B, the laminated structure of the EL layer 113R, mask layer 118R, and mask layer 119R remains on the conductive layer 112R. In addition, the conductive layers 112G and 112B are exposed. 【0370】 Figure 25B shows an example where the edge of the EL layer 113R is located outside the edge of the conductive layer 112R. This configuration allows for a higher aperture ratio of the pixels. Although not shown in Figure 25B, the etching process may result in the formation of recesses in areas of the insulating layer 105 that do not overlap with the EL layer 113R. 【0371】 Furthermore, since the EL layer 113R covers the top and sides of the conductive layer 112R, subsequent processes can be carried out without exposing the conductive layer 112R. If the edges of the conductive layer 112R are exposed, corrosion may occur, for example, during the etching process. Products generated by the corrosion of the conductive layer 112R may be unstable; for example, in the case of wet etching, they may dissolve in the solution, and in the case of dry etching, there is a concern that they may scatter into the atmosphere. Dissolution of the products into the solution or scattering into the atmosphere may cause the products to adhere to the surface to be processed and the sides of the EL layer 113R, for example, adversely affecting the characteristics of the light-emitting element or potentially forming a leak path between multiple light-emitting elements. In addition, in areas where the edges of the conductive layer 112R are exposed, the adhesion between layers in contact with each other decreases, which may make the EL layer 113R or the conductive layer 112R more prone to peeling. 【0372】 Therefore, by configuring the EL layer 113R to cover the upper 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, it is preferable that the resist mask 190R be provided between B1 and B2 so as to cover from the edge of the EL layer 113R to the edge of the conductive layer 112C on the EL layer 113R side. As a result, as shown in Figure 25B, the mask layer 118R and the mask layer 119R are provided between B1 and B2 so as to cover from the edge of the EL layer 113R to the edge of the conductive layer 112C on the EL layer 113R side. Therefore, for example, exposure of the insulating layer 105 between B1 and B2 can be suppressed. As a result, it is possible to suppress the removal of a portion of the insulating layer 105, insulating layer 104, and insulating layer 103 by etching or the like, and the exposure of the conductive layer 109. Therefore, it is possible to suppress the conductive layer 109 from being unintentionally electrically connected to other conductive layers. For example, it is possible to suppress 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. In particular, anisotropic dry etching is preferred. Alternatively, wet etching may be used. 【0375】 When using the dry etching method, the degradation of the EL film 113Rf can be suppressed by not using an oxygen-containing gas as the etching gas. 【0376】 Furthermore, an etching gas containing oxygen may be used. Including oxygen in the etching gas can increase the etching rate. Therefore, etching can be performed under low power conditions while maintaining a sufficiently fast etching rate. This suppresses damage to the EL film 113Rf. In addition, it suppresses problems such as the adhesion of reaction products generated during etching. 【0377】 When using the dry etching method, it is preferable to use a gas containing one or more of the Group 18 elements, such as H2, CF4, C4F8, SF6, CHF3, Cl2, H2O, BCl3, or 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, a gas containing H2 and Ar, or a gas containing CF4 and He, can be used as the etching gas. Also, for example, a gas containing CF4, He, and oxygen can be used as the etching gas. Furthermore, for example, a gas containing H2 and Ar, and a gas containing oxygen, can be used as the etching gas. 【0378】 As described above, in one aspect of the present invention, a resist mask 190R is formed on a mask film 119Rf, and a mask layer 119R is formed by removing a portion of the mask film 119Rf using the resist mask 190R. Subsequently, an EL layer 113R is formed by removing a portion of the EL film 113Rf using the mask layer 119R as a mask. Thus, it can be said that an EL layer 113R is formed by processing the EL film 113Rf using a photolithography method. Note that a portion of the EL film 113Rf may be removed using the resist mask 190R. Subsequently, 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, the surface state of the conductive layer 112G may change to hydrophilic. By performing a hydrophobic treatment on the conductive layer 112G, the adhesion between the conductive layer 112G and the layer formed in a later process (in this case, the EL layer 113G) can be improved, and film peeling can be suppressed. However, the hydrophobic treatment is not required. 【0380】 Next, as shown in Figure 25C, the 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. 【0381】 The EL film 113Gf can be formed by a method similar to that used for forming the EL film 113Rf. 【0382】 Next, as shown in Figure 25C, a mask film 118Gf, which will later become mask layer 118G, and a mask film 119Gf, which will later become mask layer 119G, are formed in order on the EL film 113Gf and the mask layer 119R, respectively. After that, a resist mask 190G is formed. The materials and formation methods for mask films 118Gf and 119Gf are the same as those applicable to mask films 118Rf and 119Rf. The materials and formation methods for resist mask 190G are the same as those applicable to resist mask 190R. 【0383】 The resist mask 190G is placed in a position that overlaps with the conductive layer 112G. 【0384】 Next, as shown in Figures 25C and 25D, a portion of the mask film 119Gf is removed using the resist mask 190G to form the mask layer 119G. The mask layer 119G remains on the conductive layer 112G. After that, the resist mask 190G is removed. Next, the mask layer 119G is used as a mask to remove a portion of the mask film 118Gf to form the mask layer 118G. Next, the EL film 113Gf is processed to form the EL layer 113G. For example, the mask layer 119G and the mask layer 118G are used as masks to remove a portion of the EL film 113Gf to form the EL layer 113G. 【0385】 As a result, as shown in Figure 25D, the laminated structure of the EL layer 113G, mask layer 118G, and mask layer 119G remains on the conductive layer 112G. In addition, the mask layer 119R and conductive layer 112B are exposed. 【0386】 Next, it is preferable to perform a hydrophobic treatment on the conductive layer 112B, for example. During processing of the EL film 113Gf, the surface state of the conductive layer 112B may change to hydrophilic. For example, by performing a hydrophobic treatment on the conductive layer 112B, the adhesion between the conductive layer 112B and the layer formed in a later process (in this case, the EL layer 113B) can be improved, and film peeling can be suppressed. However, the hydrophobic treatment is not required. 【0387】 Next, as shown in Figure 26A, the 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 the same method as that used to form the EL film 113Rf. 【0389】 Next, as shown in Figure 26A, a mask film 118Bf, which will later become mask layer 118B, and a mask film 119Bf, which will later become mask layer 119B, are formed in order on the EL film 113Bf and the mask layer 119R, respectively. After that, the resist mask 190B is formed. The materials and formation methods for mask films 118Bf and 119Bf are the same as those applicable to mask films 118Rf and 119Rf. The materials and formation methods for resist mask 190B are the same as those applicable to resist mask 190R. 【0390】 The resist mask 190B is placed in a position that overlaps with the conductive layer 112B. 【0391】 Next, as shown in Figures 26A and 26B, a portion of the mask film 119Bf is removed using the resist mask 190B to form the mask layer 119B. The mask layer 119B remains on the conductive layer 112B. After that, the resist mask 190B is removed. Next, the mask layer 119B is used as a mask to remove a portion of the mask film 118Bf to form the mask layer 118B. Next, the EL film 113Bf is processed to form the EL layer 113B. For example, the mask layer 119B and the mask layer 118B are used as masks to remove a portion of the EL film 113Bf to form the EL layer 113B. 【0392】 As a result, as shown in Figure 26B, the laminated structure of the EL layer 113B, mask layer 118B, and mask layer 119B remains on the conductive layer 112B. In addition, mask layers 119R and 119G are exposed. 【0393】 Furthermore, it is preferable that the side surfaces of EL layer 113R, EL layer 113G, and EL layer 113B are perpendicular or approximately perpendicular to the surface to be formed. For example, it is preferable that the angle between the surface to be formed and these side surfaces be 60 degrees or more and 90 degrees or less. 【0394】 As described above, the distance between two adjacent EL layers 113R, EL layer 113G, and EL layer 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, this distance can be defined, for example, as the distance between two adjacent opposing ends of EL layers 113R, EL layer 113G, and EL layer 113B. By narrowing the distance between the island-shaped EL layers 113 in this way, a display device with high resolution and a large aperture ratio can be provided. 【0395】 Next, as shown in Figure 26C, it is preferable to remove the mask layer 119R, mask layer 119G, and mask layer 119B. Depending on the subsequent process, the mask layer 118R, mask layer 118G, mask layer 118B, mask layer 119R, mask layer 119G, and mask layer 119B may remain in the display device. By removing the mask layer 119R, mask layer 119G, and mask layer 119B at this stage, it is possible to suppress the remaining presence of the mask layer 119R, mask layer 119G, and mask layer 119B in the display device. For example, when conductive materials are used for the mask layer 119R, mask layer 119G, and mask layer 119B, removing the mask layer 119R, mask layer 119G, and mask layer 119B in advance can suppress the generation of leakage current and the formation of capacitance due to the remaining mask layer 119R, mask layer 119G, and mask layer 119B. 【0396】 In this embodiment, the case where mask layers 119R, 119G, and 119B are removed will be described as an example, but mask layers 119R, 119G, and 119B do not need to be removed. For example, if mask layers 119R, 119G, and 119B contain the aforementioned material that has light-shielding properties against ultraviolet rays, it is preferable to proceed to the next step without removing them, as this can protect the EL layer 113 from ultraviolet rays. 【0397】 The same method as the mask layer processing method can be used for the mask layer removal process. In particular, by using the wet etching method, the damage inflicted on the EL layer 113R, EL layer 113G, and EL layer 113B when removing the mask layer can be reduced compared to when using the dry etching method. 【0398】 Alternatively, the mask layer may be removed by dissolving it in a solvent such as water or alcohol. Examples of alcohols include 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 EL layer 113R, EL layer 113G, and EL layer 113B, as well as water adsorbed on the surfaces of EL layer 113R, EL layer 113G, and 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 to 200°C, preferably 60°C to 150°C, and more preferably 70°C to 120°C. A reduced pressure atmosphere is preferable because it allows drying at a lower temperature. 【0400】 Next, as shown in Figure 26D, an insulating film 125f, which will later become the insulating layer 125, is formed to cover the EL layer 113R, EL layer 113G, EL layer 113B, mask layer 118R, mask layer 118G, and mask layer 118B. 【0401】 As described later, an insulating film is formed in contact with the upper surface of the insulating film 125f, which will later become the insulating layer 127. For this reason, it is preferable that the upper surface of the insulating film 125f has a high affinity for the material used for the insulating film, for example, a photosensitive resin composition containing acrylic resin. To improve this affinity, it is preferable to perform a surface treatment to make the upper surface of the insulating film 125f hydrophobic or to increase its hydrophobicity. For example, it is preferable to perform the treatment using a silylation agent such as HMDS. By making the upper surface of the insulating film 125f hydrophobic in this way, the insulating film 127f can be formed with good adhesion. The aforementioned hydrophobic treatment may be performed as the surface treatment. 【0402】 Next, as shown in Figure 27A, an insulating film 127f, which will later become the insulating layer 127, is formed on the insulating film 125f. 【0403】 It is preferable that the insulating film 125f and insulating film 127f are formed using a method that causes minimal damage to the EL layer 113R, EL layer 113G, and EL layer 113B. In particular, since insulating film 125f is formed in contact with the sides of the EL layer 113R, EL layer 113G, and EL layer 113B, it is preferable that it be formed using a method that causes less damage to the EL layer 113R, EL layer 113G, and EL layer 113B than insulating film 127f. 【0404】 Furthermore, insulating film 125f and insulating film 127f are formed at a temperature lower than the heat resistance temperature of EL layer 113R, EL layer 113G, and EL layer 113B, respectively. In addition, by increasing the substrate temperature during film formation of insulating film 125f, it is possible to create a film with a low impurity concentration and high barrier properties against at least one of water and oxygen, even with a thin film thickness. 【0405】 The substrate temperature when forming insulating film 125f and insulating film 127f is preferably 60°C or higher, 80°C or higher, 100°C or higher, or 120°C or higher, and preferably 200°C or lower, 180°C or lower, 160°C or lower, 150°C or lower, or 140°C or lower. 【0406】 As the insulating film 125f, it is preferable to form an insulating film with 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 using, for example, the ALD method. The ALD method is preferable because it can reduce film formation damage and allow for the formation of a highly covering film. For example, it is preferable to form an aluminum oxide film as the insulating film 125f using the ALD method. 【0408】 In addition, the insulating film 125f may be formed using a sputtering method, CVD method, or PECVD method, which have a faster deposition rate than the ALD method. This allows for the production of highly reliable display devices with high productivity. 【0409】 The insulating film 127f is preferably formed using the wet film formation method described above. The insulating film 127f is preferably formed using a photosensitive material by, for example, spin coating, and more specifically, it is preferably formed using a photosensitive resin composition containing an acrylic resin. 【0410】 The insulating film 127f is preferably formed using a resin composition having, for example, a polymer, an acid generator, and a solvent. The polymer is formed using one or more monomers and has a structure in which one or more structural units (also called constituent units) are repeated regularly or irregularly. As the acid generator, one or both of a compound that generates acid upon irradiation with light and a compound that generates acid upon heating can be used. The resin composition may further contain one or more of a photosensitive agent, a sensitizer, a catalyst, an adhesion aid, a surfactant, and an antioxidant. 【0411】 Furthermore, it is preferable to perform a heat treatment (also called pre-baking) after the formation of the insulating film 127f. This heat treatment is performed at a temperature lower than the heat resistance temperature of the EL layer 113R, EL layer 113G, and EL layer 113B. The substrate temperature during the heat treatment is preferably 50°C to 200°C, more preferably 60°C to 150°C, and even more preferably 70°C to 120°C. This makes it possible to remove the solvent contained in the insulating film 127f. 【0412】 Next, exposure is performed to expose a portion of the insulating film 127f to visible light or ultraviolet light. Here, if a positive-type photosensitive resin composition containing acrylic resin is used for the insulating film 127f, visible light or ultraviolet light is irradiated to the area where the insulating layer 127 will not be formed in a later step. The insulating layer 127 is formed in the area sandwiched between any two of the conductive layers 112R, 112G, and 112B, and around the conductive layer 112C. Therefore, visible light or ultraviolet light is irradiated onto the conductive layer 112R, the conductive layer 112G, the conductive layer 112B, and the conductive layer 112C. If a negative-type photosensitive material is used for the insulating film 127f, visible light or ultraviolet light is irradiated to the area 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 exposure area of ​​the insulating film 127f. In this embodiment, the insulating layer 127 is processed so that it has a portion that overlaps with the upper surface of the conductive layer 111. 【0414】 The light used for exposure preferably includes the i-line (wavelength 365 nm). Furthermore, the light used for exposure may also include at least one of the g-line (wavelength 436 nm) and the 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, the diffusion of oxygen into the EL layers 113R, 113G, and 113B can be reduced. When an EL layer is irradiated with light (visible light or ultraviolet light), the organic compounds contained in the EL layer may become excited, and their reaction with oxygen in the atmosphere may be promoted. More specifically, when an EL layer is irradiated with light (visible light or ultraviolet light) in an oxygen-containing atmosphere, oxygen may bond to the organic compounds in the EL layer. By providing the mask layer 118 and the insulating film 125f on an island-shaped EL layer, the bonding of oxygen in the atmosphere to the organic compounds contained in the EL layer can be reduced. 【0416】 Next, as shown in Figures 27B1 and 27B2, development is performed to remove the exposed area of ​​the insulating film 127f and form the insulating layer 127a. Figure 27B2 is an enlarged view of the EL layer 113G shown in Figure 27B1 and the edge and vicinity of the insulating layer 127a. The insulating layer 127a is formed in the region sandwiched between any two of the conductive layers 112R, 112G, and 112B, and in the region surrounding the conductive layer 112C. When acrylic resin is used for the insulating film 127f, it is preferable to use an alkaline solution as the developer, for example, TMAH can be used. 【0417】 Next, the residue (so-called scum) from the development process may be removed. For example, the residue can be removed by ashing using oxygen plasma. 【0418】 Furthermore, etching may be performed to adjust the surface height of the insulating layer 127a. The insulating layer 127a may be processed, for example, by ashing using oxygen plasma. Also, even when a non-photosensitive material is used as the insulating film 127f, the surface height of the insulating film 127f can be adjusted, for example, by ashing. 【0419】 Next, as shown in Figures 28A and 28B, etching is performed using the insulating layer 127a as a mask to remove a portion of the insulating film 125f, thereby thinning the film thickness of parts of the mask layer 118R, mask layer 118G, and mask layer 118B. As a result, the insulating layer 125 is formed beneath the insulating layer 127a. In addition, the surfaces of the thinned portions of the mask layer 118R, mask layer 118G, and mask layer 118B are exposed. Figure 28B is a magnified view of the EL layer 113G shown in Figure 28A, the edge of the insulating layer 127a, and its vicinity. In the following, the etching process using the insulating layer 127a as a mask may be referred to as the first etching process. 【0420】 The first etching process can be carried out by dry etching or wet etching. It is preferable that the insulating film 125f is deposited using the same material as the mask layer 118R, mask layer 118G, and mask layer 118B, as this allows the first etching process to be performed in a single step. 【0421】 As shown in Figure 28B, by etching using the insulating layer 127a, which has a tapered side surface, as a mask, the side surface of the insulating layer 125, as well as the upper edges of the mask layers 118R, 118G, and 118B, can be made tapered relatively easily. 【0422】 When performing dry etching, it is preferable to use a chlorine-based gas. As the chlorine-based gas, one or more gases selected from Cl2, BCl3, SiCl4, and CCl4 can be used. In addition, one or more gases selected from oxygen gas, hydrogen gas, helium gas, and argon gas can be added to the above chlorine-based gas as appropriate. By using dry etching, thin areas of the mask layer 118R, mask layer 118G, and mask layer 118B can be formed with good in-plane uniformity. 【0423】 As a dry etching apparatus, a dry etching apparatus having a high-density plasma source can be used. As a dry etching apparatus having a high-density plasma source, for example, an inductively coupled plasma (ICP) etching apparatus can be used. Alternatively, a capacitively coupled plasma (CCP) etching apparatus having parallel plate electrodes can be used. The capacitively coupled plasma etching apparatus having parallel plate electrodes may be configured to apply a high-frequency voltage to one electrode of the parallel plate electrodes. Alternatively, it may be configured to apply multiple different high-frequency voltages to one electrode 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 generated during dry etching may accumulate on the upper and side surfaces of the insulating layer 127a. As a result, components contained in the etching gas, components contained in the insulating film 125f, and components contained in the mask layer 118R, mask layer 118G, and mask layer 118B may be present in the insulating layer 127 after the display device is completed. 【0425】 Furthermore, it is preferable to perform the first etching process by wet etching. By using the wet etching method, damage to the EL layer 113R, EL layer 113G, and EL layer 113B can be reduced compared to when the dry etching method is used. For example, wet etching can be performed using an alkaline solution. For example, it is preferable to use TMAH, an alkaline solution, for wet etching of an aluminum oxide film. In this case, wet etching can be performed using a paddle method. It is also preferable if the insulating film 125f is formed using the same material as the mask layer 118R, mask layer 118G, and mask layer 118B, as the above etching process can be performed all at once. 【0426】 As shown in Figures 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 thickness is reduced. By leaving the corresponding mask layers 118R, 118G, and 118B on the EL layers 113R, 113G, and 113B in this way, damage to the EL layers 113R, 113G, and 113B in subsequent processing steps can be suppressed. 【0427】 In Figures 28A and 28B, the mask layers 118R, 118G, and 118B are configured to have thin films, but the present invention is not limited to this. For example, depending on the film thickness of the insulating film 125f and the film 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 thinning a portion of the insulating film 125f. Also, if the insulating film 125f is formed using the same material as the mask layers 118R, 118G, and 118B, the boundary between the insulating film 125f and the mask layers 118R, 118G, and 118B may become unclear. As a result, it may be impossible to determine whether the insulating layer 125 has been formed, or whether the film thickness of the mask layer 118R, mask layer 118G, and mask layer 118B has decreased. 【0428】 Furthermore, while Figures 28A and 28B show examples where the shape of the insulating layer 127a has not changed from that shown in Figures 27B1 and 27B2, the present invention is not limited to this. For example, the edges of the insulating layer 127a may droop and cover the edges of the insulating layer 125. Also, for example, the edges of the insulating layer 127a may come into contact with the upper surfaces of the mask layer 118R, mask layer 118G, and mask layer 118B. As mentioned above, if the insulating layer 127a is not exposed after development, the shape of the insulating layer 127a may change easily. 【0429】 Next, it is preferable to expose the entire substrate to visible light or ultraviolet light and irradiate the insulating layer 127a. The energy density of this exposure is 0 mJ / cm². 2 A larger 800 mJ / cm² 2 The following is preferable: 0 mJ / cm 2 A larger 500 mJ / cm² 2 The following is more preferable: Performing such exposure after development may improve the transparency of the insulating layer 127a. In addition, it may be possible to lower the substrate temperature required for the heat treatment in a later process to deform the insulating layer 127a into a tapered shape. 【0430】 On the other hand, as will be described later, by not exposing the insulating layer 127a, it may be easier to change the shape of the insulating layer 127a or to deform the insulating layer 127 into a tapered shape in a later process. Therefore, it may be preferable not to expose the insulating layer 127a after development. 【0431】 For example, when a photocurable resin is used as the material for the insulating layer 127a, polymerization is initiated by exposure to light, and the insulating layer 127a can be cured. Alternatively, at this stage, the insulating layer 127a may not be exposed to light, and at least one of the post-bake and the second etching process described later may be performed while the insulating layer 127a is in a state where it is relatively easy to change shape. This can suppress the occurrence of irregularities on the surface forming the common layer 114 and the common electrode 115, and can also suppress the common layer 114 and the common electrode 115 from being broken into steps. Alternatively, exposure may be performed after development and before the first etching process. On the other hand, depending on the material of the insulating layer 127a (e.g., positive-type 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 post-bake. This makes it possible to stably produce an insulating layer 127a of the desired shape with high reproducibility. 【0432】 Here, it is preferable to irradiate with visible light or ultraviolet light in an atmosphere that does not contain oxygen or has a low oxygen content. For example, it is preferable to irradiate with visible light or ultraviolet light in an inert gas atmosphere such as a nitrogen atmosphere or a reduced pressure atmosphere. If the above-mentioned irradiation of visible light or ultraviolet light is carried out in an atmosphere that contains a lot of oxygen, the compounds contained in the EL layer 113 may oxidize and deteriorate. However, by irradiating with visible light or ultraviolet light in an atmosphere that does not contain oxygen or has a low oxygen content, the deterioration of the EL layer can be suppressed, and a more reliable display device can be provided. 【0433】 Next, as shown in Figures 29A and 29B, a heat treatment (also called post-bake) is performed. As shown in Figures 29A and 29B, by performing the heat treatment, the insulating layer 127a can be deformed into an insulating layer 127 having a tapered shape on its side surface. As mentioned above, the shape of the insulating layer 127a may have already changed and have a tapered shape on its side surface by the time the first etching treatment is completed. This 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 atmospheric atmosphere or an inert gas atmosphere. The heating atmosphere may also be an atmospheric pressure atmosphere or a reduced pressure atmosphere. A reduced pressure atmosphere is preferable because it allows drying at a lower temperature. It is preferable that the substrate temperature for this step is higher than that for the heat treatment after the formation of the insulating film 127f (pre-bake). This improves the adhesion between the insulating layer 127 and the insulating layer 125, and also improves the corrosion resistance of the insulating layer 127. Figure 29B is an enlarged view of the EL layer 113G shown in Figure 29A, and the edge and vicinity of the insulating layer 127. 【0434】 As described above, in one embodiment of the present invention, a highly heat-resistant material is used for the light-emitting element. Therefore, the pre-bake temperature and post-bake temperature can be set to 100°C or higher, 120°C or higher, or 140°C or higher, respectively. This further improves the adhesion between the insulating layer 127 and the insulating layer 125, and also improves the corrosion resistance of the insulating layer 127. Furthermore, it broadens the range of materials that can be used as the insulating layer 127. In addition, for example, by sufficiently removing the solvent contained in the insulating layer 127, it is possible to suppress the penetration of impurities such as water and oxygen into the EL layer 113. 【0435】 In the first etching process, the mask layers 118R, 118G, and 118B are not completely removed, but rather left in a thinned state. This prevents damage and degradation of the EL layers 113R, 113G, and 113B during post-bake, for example. Therefore, the reliability of the light-emitting element can be improved. 【0436】 Furthermore, depending on the material of the insulating layer 127, as well as the post-bake temperature, time, and atmosphere, a concave curved shape may be formed on the side surface of the insulating layer 127, as shown in Figures 7A and 7B. For example, the higher the temperature or the longer the post-bake conditions, the more likely the shape of the insulating layer 127 is to change, and a concave curved shape may be formed. Also, as mentioned above, if the insulating layer 127a is not exposed after development, the shape of the insulating layer 127 may change during post-bake. 【0437】 Next, as shown in Figures 30A and 30B, etching is performed using the insulating layer 127 as a mask to remove a portion of the mask layer 118R, mask layer 118G, and mask layer 118B. In some cases, a portion of the insulating layer 125 may also be removed. As a result, openings are formed in the mask layers 118R, 118G, and 118B, respectively, exposing the upper surfaces of the EL layer 113R, EL layer 113G, EL layer 113B, and conductive layer 112C. Figure 30B is a magnified view of the EL layer 113G and the edge and vicinity of the insulating layer 127 shown in Figure 30A. In the following, the etching process using the insulating layer 127 as a mask may be referred to as the second etching process. 【0438】 The edges of the insulating layer 125 are covered with the insulating layer 127. Figures 30A and 30B also show an example where a portion of the edge of the mask layer 118G, specifically the tapered portion formed by the first etching process, is covered by the insulating layer 127, while 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 omitted and the etching of the insulating layer 125 and the mask layer is performed all at once after post-baking, side etching may cause the insulating layer 125 and the mask layer beneath the edges of the insulating layer 127 to disappear, forming a cavity. This cavity can cause unevenness on the surface forming the common layer 114 and the common electrode 115, making it easier for steps to occur in the common layer 114 and the common electrode 115. Even if the insulating layer 125 and the mask layer are side-etched and a cavity is formed in the first etching process, the insulating layer 127 can fill the cavity by performing post-baking afterward. Subsequently, in the second etching process, the mask layer, which is now thinner, is etched, resulting in less side etching and making it less likely for a cavity to form, or if a cavity does form, it can be made extremely small. As a result, the surface forming the common layer 114 and the common electrode 115 can be made flatter. 【0440】 Furthermore, as shown in Figures 6A, 6B, or 8A, 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. Also, for example, the edge of the insulating layer 127 may be in contact with at least one upper surface of the EL layer 113R, EL layer 113G, and EL layer 113B. As mentioned above, if the insulating layer 127a is not exposed after development, the shape of the insulating layer 127 may change easily. 【0441】 The second etching process is performed by wet etching. By using the wet etching method, damage to the EL layer 113R, EL layer 113G, and EL layer 113B can be reduced compared to using the dry etching method. Wet etching can be performed using an alkaline solution such as TMAH. 【0442】 On the other hand, when performing a second etching process using a wet etching method, if there are gaps 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 due to adhesion problems between the EL layer 113 and other layers, the chemical used in the second etching process may penetrate these gaps and come into contact with the pixel electrodes. If the chemical 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. As a result, the yield of the display device may decrease. Furthermore, the reliability of the display device may decrease. 【0443】 In a method for manufacturing a display device according to one aspect of the present invention, as described above, the conductive layer 112 is formed to cover the upper and side surfaces of the conductive layer 111. This makes it possible to suppress contact between the chemical solution and the conductive layer 111 during the second etching process, even if there are gaps 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. This makes it possible to suppress corrosion of the pixel electrodes and, for example, corrosion of the conductive layer 112. Therefore, a method for manufacturing a display device according to one aspect of the present invention can be a manufacturing method with a high yield. Furthermore, a method for manufacturing a display device according to one aspect of the present invention can be a manufacturing method that suppresses the occurrence of defects. 【0444】 As described above, by providing insulating layer 127, insulating layer 125, mask layer 118R, mask layer 118G, and mask layer 118B, connection failures caused by the divided portion and increases in electrical resistance caused by locally thin film thickness can be suppressed between each light-emitting element in the common layer 114 and common electrode 115. As a result, a display device according to one embodiment of the present invention can improve display quality. 【0445】 Furthermore, after exposing a portion of the EL layer 113R, EL layer 113G, and EL layer 113B, a further heat treatment may be performed. This heat treatment can remove water contained in the EL layer 113 and water adsorbed on the surface of the EL layer 113. In addition, this heat treatment may change the shape of the insulating layer 127. Specifically, the insulating layer 127 may spread to cover at least one of the following: the edge of the insulating layer 125, the edges of the mask layer 118R, mask layer 118G, and mask layer 118B, and the upper surface of the EL layer 113R, EL layer 113G, and EL layer 113B. For example, the insulating layer 127 may take on the shape shown in Figures 6A and 6B. For example, the heat treatment can be performed in an inert gas atmosphere or a reduced pressure atmosphere. The heat treatment can be performed at a substrate temperature of 50°C to 200°C, preferably 60°C to 150°C, and more preferably 70°C to 120°C. Using a reduced pressure atmosphere is preferable because it allows for dehydration at a lower temperature. However, it is preferable to appropriately set the temperature range for the above heat treatment, taking into account the heat resistance temperature of the EL layer 113. When considering the heat resistance temperature of the EL layer 113, a temperature of 70°C to 120°C is particularly preferable within the above temperature range. 【0446】 Next, as shown in Figure 31A, a common layer 114 is formed on the EL layer 113R, EL layer 113G, EL layer 113B, conductive layer 112C, and insulating layer 127. The common layer 114 can be formed by methods such as vapor deposition (including vacuum deposition), transfer, printing, inkjet, or coating. 【0447】 Next, as shown in Figure 31A, a common electrode 115 is formed on the common layer 114. The common electrode 115 can be formed by sputtering or vacuum deposition. Alternatively, the common electrode 115 may be formed by laminating 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 has been formed, without any intermediate steps 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 to the atmosphere. In other words, the common layer 114 and the common electrode 115 can be formed in a continuous vacuum. As a result, the underside of the common electrode 115 can be made cleaner than when the display device 100 does not have a common layer 114. Therefore, the light-emitting element 130 can be made into a light-emitting element with high reliability and good characteristics. 【0449】 Next, as shown in Figure 31B, a protective layer 131 is formed on the common electrode 115. The protective layer 131 can be formed by methods such as vacuum deposition, sputtering, CVD, or ALD. 【0450】 Next, by bonding the substrate 120 onto the protective layer 131 using the resin layer 122, a display device having the configuration shown in Figure 2A and the configuration shown in Figure 18A can be manufactured. As described above, in one embodiment of the present invention, the method for manufacturing a display device improves yield and suppresses the occurrence of defects by forming the conductive layer 112 so as to cover the upper and side surfaces of the conductive layer 111. 【0451】 Here, after forming the insulating layer 127 by performing the post-bake shown in Figures 29A and 29B, exposure may be performed on the insulating layer 127. For example, exposure may be performed on the insulating layer 127 if the aforementioned exposure is not performed on the insulating layer 127a. For example, exposure may be performed on the insulating layer 127 after the second etching process shown in Figures 30A and 30B, and before the formation of the common layer 114 shown in Figure 31A. Alternatively, exposure may be performed on the insulating layer 127 after the formation of the common electrode 115 shown in Figure 31A, and before the formation of the protective layer 131 shown in Figure 31B. Alternatively, exposure may be performed on the insulating layer 127 after the formation of the protective layer 131 shown in Figure 31B. Here, for example, conditions similar to those that can be applied to the exposure of the insulating layer 127a can be applied as conditions for exposure of the insulating layer 127. Furthermore, exposure of the insulating layer 127a and the insulating layer 127 does not need to be performed even once, may be performed only once in total, or may be performed two or more times in total. 【0452】 For example, when a photocurable resin is used as the insulating layer 127, the insulating layer 127 can be cured by exposure. This suppresses deformation of the insulating layer 127. Therefore, for example, peeling of the layer on the insulating layer 127 can be suppressed. Based on the above, a display device according to one aspect of the present invention can be made into a highly reliable display device. 【0453】 As described above, in the method for manufacturing a display device according to one aspect of the present invention, the island-shaped EL layers 113R, 113G, and 113B are formed not using a fine metal mask, but by processing after depositing a film on one surface, so that the island-shaped layers can be formed with a uniform thickness. This makes it possible to realize a high-definition display device or a display device with a high aperture ratio. Furthermore, even if the resolution or aperture ratio is high and the distance between subpixels is extremely short, it is possible to suppress contact between adjacent subpixels between EL layers 113R, 113G, and 113B. Therefore, it is possible to suppress the generation of lateral leakage current between subpixels. As a result, crosstalk caused by unintended light emission can be suppressed, and a display device with extremely high contrast can be realized. 【0454】 Furthermore, by providing an insulating layer 127 having a tapered shape at its end between adjacent island-shaped EL layers 113, it is possible to suppress the occurrence of step breaks when forming the common electrode 115, and to suppress the formation of locally thin areas in the common electrode 115. As a result, connection failures caused by the divided areas and increases in electrical resistance caused by locally thin areas in the common layer 114 and common electrode 115 can be suppressed. Therefore, a display device according to one aspect of the present invention can achieve both high resolution and high display quality. 【0455】 [Example of manufacturing method 2] In the following, examples of methods for manufacturing a display device 100 having the configuration shown in Figure 10 and the configuration shown in Figure 18C will be explained with reference to the drawings. Note that the explanation will mainly focus on methods different from those described in Figures 24A to 31B, and methods identical to those described in Figures 24A to 31B will be omitted as appropriate. 【0456】 Figures 32A to 32C show the same process as in Figures 24A to 24C. 【0457】 Figure 32D1 is an enlarged view of the cross-section between B1 and B2 shown in Figure 32C. In the example shown in Figure 32D1, the conductive film 112f has a region that overlaps with the conductive layer 109. 【0458】 Figure 32D2 is a modified example of Figure 32D1, showing an example where the conductive film 112f does not overlap with the conductive layer 109. For example, after forming the conductive film 112f as shown in Figure 32C, the configuration shown in Figure 32D2 can be fabricated by removing a portion of the conductive film 112f in the region between B1 and B2. When the process shown in Figure 32D2 is performed, the configuration between B1 and B2 of the fabricated display device 100 will be, for example, the configuration shown in Figure 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 no longer overlap with the conductive layer 109. Therefore, as mentioned above, the generation of parasitic capacitance can be suppressed. It should also be assumed that the conductive layer 112C is formed by the process shown in Figure 32D2. In other words, in Figure 32D2, the conductive film 112f may be replaced with the conductive layer 112C. 【0460】 In the following, we will describe an example of a manufacturing method for the display device 100 assuming that the steps shown in Figure 32D2 are not performed. However, even if the steps shown in Figure 32D2 are performed, you can still refer to the following description of the manufacturing method example. 【0461】 Next, as mentioned above, it is preferable to perform a hydrophobic treatment on the conductive film 112f. 【0462】 Next, as shown in Figure 33A, an EL film 113Rf, which will later become the EL layer 113R, is formed on the conductive film 112f using the same method as shown in Figure 25A. Then, 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 sequentially on the EL film 113Rf and the conductive film 112f using the same method as shown in Figure 25A. 【0463】 Next, as shown in Figure 33A, a resist mask 190R is formed on the mask film 119Rf using the same method as shown in Figure 25A. The resist mask 190R is placed in a position that overlaps with the conductive layer 111R. The resist mask 190R can also be placed in a position that overlaps with the conductive layer 111C. 【0464】 Next, as shown in Figures 33A and 33B, a portion of the mask film 119Rf is removed using the resist mask 190R in the same manner as shown in Figures 25A and 25B to form a mask layer 119R. The mask layer 119R remains on the conductive layer 111R and the conductive layer 111C. Subsequently, the resist mask 190R is removed in the same manner as shown in Figures 25A and 25B. Next, a portion of the mask film 118Rf is removed using the mask layer 119R as a mask in the same manner as shown in Figures 25A and 25B to form a mask layer 118R. 【0465】 Next, as shown in Figures 33A and 33B, the EL film 113Rf is processed in the same manner as shown in Figures 25A and 25B to form the EL layer 113R. For example, mask layers 119R and 118R are used as masks to remove a portion of the EL film 113Rf and form the EL layer 113R. As a result, as shown in Figure 33B, a laminated structure of the EL layer 113R, mask layer 118R, and mask layer 119R remains on the conductive film 112f, having a region that overlaps with the conductive layer 111R. In addition, the conductive film 112f is exposed in the region where the mask layer 119R is not provided. 【0466】 It is preferable that the resist mask 190R be provided between B1 and B2 so as to cover from the edge of the EL layer 113R to the edge of the conductive layer 111C on the EL layer 113R side. As a result, as shown in Figure 33B, the mask layer 118R and the mask layer 119R are provided between B1 and B2 so as to cover from the edge of the EL layer 113R to the edge of the conductive layer 111C on the EL layer 113R side. Therefore, for example, exposure of the conductive film 112f between B1 and B2 can be suppressed. This prevents the conductive film 112f, insulating layer 105, insulating layer 104, and a part of insulating layer 103 from being removed by etching or the like, and the conductive layer 109 from being exposed. Therefore, it is possible to suppress the conductive layer 109 from being unintentionally electrically connected to other conductive layers. For example, it is possible to suppress 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 a hydrophobic treatment on the conductive film 112f, for example. During processing of the EL film 113Rf, the surface state of the conductive film 112f may change to hydrophilic. For example, by performing a hydrophobic treatment on the conductive film 112f, the adhesion between the conductive film 112f and the layer formed in a later process (in this case, the EL layer 113G) can be improved, and film peeling can be suppressed. However, the hydrophobic treatment is not required. 【0468】 Next, as shown in Figure 33C, the EL film 113Gf, which will later become the EL layer 113G, is formed on the conductive film 112f and the mask layer 119R using the same method as shown in Figure 25C. 【0469】 Next, as shown in Figure 33C, a mask film 118Gf, which will later become mask layer 118G, and a mask film 119Gf, which will later become mask layer 119G, are formed sequentially on the EL film 113Gf and the mask layer 119R, respectively, using the same method as shown in Figure 25C. After that, a resist mask 190G is formed. 【0470】 The resist mask 190G is placed in a position that overlaps with the conductive layer 111G. 【0471】 Next, as shown in Figures 33C and 33D, a portion of the mask film 119Gf is removed using the resist mask 190G in the same manner as shown in Figures 25C and 25D to form the mask layer 119G. The mask layer 119G remains on the conductive layer 111G. Subsequently, the resist mask 190G is removed in the same manner as shown in Figures 25C and 25D. Next, a portion of the mask film 118Gf is removed using the mask layer 119G as a mask in the same manner as shown in Figures 25C and 25D to form the mask layer 118G. Subsequently, the EL film 113Gf is processed in the same manner as shown in Figures 25C and 25D to form the EL layer 113G. For example, the mask layer 119G and the mask layer 118G are used as masks to remove a portion of the EL film 113Gf and form the EL layer 113G. 【0472】 As a result, as shown in Figure 33D, a laminated structure of the EL layer 113G, mask layer 118G, and 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 the region where neither the mask layer 119R nor the mask layer 119G is provided. 【0473】 Next, it is preferable to perform a hydrophobic treatment on the conductive film 112f, for example. During processing of the EL film 113Gf, the surface state of the conductive film 112f may change to hydrophilic. For example, by performing a hydrophobic treatment on the conductive film 112f, the adhesion between the conductive film 112f and the layer formed in a later process (in this case, the EL layer 113B) can be improved, and film peeling can be suppressed. However, the hydrophobic treatment is not required. 【0474】 Next, as shown in Figure 34A, the 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 using the same method as shown in Figure 26A. 【0475】 Next, as shown in Figure 34A, a mask film 118Bf, which will later become mask layer 118B, and a mask film 119Bf, which will later become mask layer 119B, are formed sequentially on the EL film 113Bf and the mask layer 119R, respectively, in the same manner as shown in Figure 26A. After that, a resist mask 190B is formed. 【0476】 The resist mask 190B is placed in a position that overlaps with the conductive layer 111B. 【0477】 Next, as shown in Figures 34A and 34B, a portion of the mask film 119Bf is removed using the resist mask 190B to form the mask layer 119B. The mask layer 119B remains on the conductive layer 111B. After that, the resist mask 190B is removed. Next, the mask layer 119B is used as a mask to remove a portion of the mask film 118Bf to form the mask layer 118B. Next, the EL film 113Bf is processed to form the EL layer 113B. For example, the mask layer 119B and the mask layer 118B are used as masks to remove a portion of the EL film 113Bf to form the EL layer 113B. 【0478】 As a result, as shown in Figure 34B, the laminated structure of the EL layer 113B, mask layer 118B, and mask layer 119B remains on the conductive layer 111B. In addition, mask layers 119R and 119G are exposed, and the conductive film 112f is exposed in the regions where none of the mask layers 119R, 119G, or 119B are provided. 【0479】 Next, as shown in Figures 34B and 34C, a portion of the conductive film 112f is removed using mask layers 119R, 119G, and 119B as masks, for example by 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 sides of the conductive layer 111. For example, if the conductive layer 112 is configured as shown in Figure 2B2, and a metal material is used as the conductive layer 112a and a conductive oxide is used as the conductive layer 112b, a portion of the conductive film that will become conductive layer 112b can be removed by wet etching, and then a portion of the conductive film that will become conductive layer 112a can be removed by dry etching. 【0480】 Next, as shown in Figure 35A, it is preferable to remove the mask layer 119R, mask layer 119G, and mask layer 119B using the same method as shown in Figure 26C. 【0481】 Next, as shown in Figure 35B, an insulating film 125f, which will later become the insulating layer 125, is formed in the same manner as shown in Figure 26D, so as to cover the 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 the same process as in Figures 27A, 27B1, 28A, 29A, 30A, 31A, and 31B, respectively. After the process shown in Figure 37B, the substrate 120 is bonded onto the protective layer 131 using the resin layer 122 to produce a display device having the configuration shown in Figure 10 and the configuration shown in Figure 18C. 【0483】 [Example of manufacturing method 3] In the following section, examples of methods for manufacturing a display device 100 having the configuration shown in Figure 14 and the configuration shown in Figure 18E will be explained with reference to the drawings. Note that the explanation will mainly focus on methods different from those described in Figures 24A to 31B, and methods identical to those described in Figures 24A to 31B will be omitted as appropriate. 【0484】 First, the same process as shown in Figures 24A to 24D is performed. Subsequently, as shown in Figure 38A, the EL film 113Rf, which will later become the EL layer 113R, is formed on the conductive layer 112R, conductive layer 112G, conductive layer 112B, and insulating layer 105 using the same method as shown in Figure 25A. The EL film 113Rf has a film 113R1f that will later become the light-emitting unit 113R1, a charge-generating film 113R2f that will later become the charge-generating layer 113R2, and a film 113R3f that will later become the light-emitting unit 113R3. In Figure 38A, the charge-generating film 113Rf2 is shown by a dashed line. 【0485】 Next, as shown in Figure 38A, a mask film 118Rf, which will later become a mask layer 118R, and a mask film 119Rf, which will later become a mask layer 119R, are formed sequentially on the EL film 113Rf, the conductive layer 112C, and the insulating layer 105, respectively, using the same method as shown in Figure 25A. Subsequently, as shown in Figure 38A, a resist mask 190R is formed on the mask film 119Rf using the same method as shown in Figure 25A. 【0486】 Next, as shown in Figures 38A and 38B, a portion of the mask film 119Rf is removed using the resist mask 190R in the same manner as shown in Figures 25A and 25B, forming a mask layer 119R. The mask layer 119R remains on the conductive layer 111R and the conductive layer 111C. Subsequently, the resist mask 190R is removed in the same manner as shown in Figures 25A and 25B. Next, a portion of the mask film 118Rf is removed using the mask layer 119R as a mask in the same manner as shown in Figures 25A and 25B, forming a mask layer 118R. 【0487】 Next, as shown in Figures 38A and 38B, the EL film 113Rf is processed in the same manner as shown in Figures 25A and 25B to form the EL layer 113R. For example, a portion of the EL film 113Rf is removed using mask layers 119R and 118R as masks to form the EL layer 113R. As described above, the EL layer 113R includes 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 charge generation layer 113R2 is shown by a dashed line. 【0488】 Next, if the conductive layer 112G is subjected to a hydrophobic treatment, for example, as described above, the adhesion between the conductive layer 112G and the layer formed in a later step (in this case, the EL layer 113G) can be improved, and film peeling can be suppressed, which is preferable. However, the hydrophobic treatment is not required. 【0489】 Next, as shown in Figure 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 using the same method as shown in Figure 25C. The EL film 113Gf has 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 Figure 38C, the charge-generating film 113Gf2 is shown by a dashed line. 【0490】 Next, as shown in Figure 38C, a mask film 118Gf, which will later become mask layer 118G, and a mask film 119Gf, which will later become mask layer 119G, are formed sequentially on the EL film 113Gf and the mask layer 119R, respectively, using the same method as shown in Figure 25C. After that, a resist mask 190G is formed using the same method as shown in Figure 25C. 【0491】 Next, as shown in Figures 38C and 38D, a portion of the mask film 119Gf is removed using the resist mask 190G in the same manner as shown in Figures 25C and 25D to form the mask layer 119G. Then, the resist mask 190G is removed in the same manner as shown in Figures 25C and 25D. Next, a portion of the mask film 118Gf is removed using the mask layer 119G as a mask in the same manner as shown in Figures 25C and 25D to form the mask layer 118G. Subsequently, the EL film 113Gf is processed in the same manner as shown in Figures 25C and 25D to form the EL layer 113G. As described above, the EL layer 113G includes 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 charge generation layer 113G2 is shown by a dashed line. 【0492】 Next, as shown in Figure 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 using the same method as shown in Figure 26A. The EL film 113Bf has 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 Figure 39A, the charge-generating film 113Bf2 is shown by a dashed line. 【0493】 Next, as shown in Figure 39A, a mask film 118Bf, which will later become mask layer 118B, and a mask film 119Bf, which will later become mask layer 119B, are formed sequentially on the EL film 113Bf and the mask layer 119R, respectively, using the same method as shown in Figure 26A. After that, a resist mask 190B is formed using the same method as shown in Figure 26A. 【0494】 Next, as shown in Figures 39A and 39B, a portion of the mask film 119Bf is removed using the resist mask 190B in the same manner as shown in Figures 26A and 26B to form the mask layer 119B. Then, the resist mask 190B is removed in the same manner as 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 the same manner as shown in Figures 26A and 26B to form the mask layer 118B. Next, the EL film 113Bf is processed in the same manner as shown in Figures 26A and 26B to form the EL layer 113B. As described above, the EL layer 113B includes a light-emitting unit 113B1, a charge generation layer 113B2 on the light-emitting unit 113B1, and a light-emitting unit 113B3 on the charge generation layer 113B2. The charge generation layer 113B2 is shown by a dashed line. 【0495】 Figures 39C, 39D, 40A to 40C, 41A, 41B, 42A, and 42B show the same process as in Figures 26C, 26D, 27A, 27B1, 28A, 29A, 30A, 31A, and 31B. After the process shown in Figure 42B, the substrate 120 is bonded onto the protective layer 131 using the resin layer 122 to produce a display device having the configuration shown in Figure 14 and the configuration shown in Figure 18E. 【0496】 [Example of manufacturing method 4] In the following section, examples of methods for manufacturing a display device 100 having the configuration shown in Figure 19A and the configuration shown in Figure 18A will be explained with reference to the drawings. Note that the explanation will mainly focus on methods different from those described in Figures 24A to 31B, and methods identical to those described in Figures 24A to 31B will be omitted as appropriate. 【0497】 First, the same process as shown in Figures 24A and 24B is performed. As a result, conductive layers 111R, 111G, 111B, and 111C are formed on the plug 106 and the insulating layer 105, as shown in Figure 43A. 【0498】 Next, as shown in Figure 43B, conductive films 112f1 are formed on conductive layer 111R, conductive layer 111G, conductive layer 111B, conductive layer 111C, and insulating layer 105. The conductive films 112f1 can be formed in the same manner as the conductive film 112f shown in Figure 24C, and the same materials as the conductive film 112f can be used. 【0499】 Next, as shown in Figures 43B and 43C, the conductive film 112f1 is processed to form a conductive layer 112B1 that covers the top and sides of the conductive layer 111B. The conductive film 112f1 can be processed in the same manner as the conductive film 112f. 【0500】 Next, as shown in Figure 43D, conductive films 112f2 are formed on conductive layer 111R, conductive layer 111G, conductive layer 112B1, conductive layer 111C, and insulating layer 105. The conductive films 112f2 can be formed in the same manner as conductive film 112f, and the same materials as conductive film 112f can be used. 【0501】 Next, as shown in Figures 43D and 43E, the conductive film 112f2 is processed to form a conductive layer 112R1 that covers the top and side surfaces of the conductive layer 111R, and a conductive layer 112B2 on the conductive layer 112B1. In Figure 43E, the boundary between the conductive layer 112B1 and the conductive layer 112B2 is shown by a dotted line. 【0502】 Next, as shown in Figure 44A, conductive films 112f3 are formed on conductive layer 112R1, conductive layer 111G, conductive layer 112B2, conductive layer 111C, and insulating layer 105. The conductive films 112f3 can be formed in the same manner as conductive films 112f, and the same materials as conductive films 112f can be used. 【0503】 Next, as shown in Figures 44A and 44B, the conductive film 112f3 is processed to form the conductive layer 112R2 on the conductive layer 112R1, the conductive layer 112G covering the top and sides of the conductive layer 111G, the conductive layer 112B3 on the conductive layer 112B2, and the conductive layer 112C covering the top and sides of the conductive layer 111C. The conductive layer 112R is formed by the conductive layer 112R1 and the conductive layer 112R2, and the conductive layer 112B is formed by the conductive layer 112B1, the conductive layer 112B2, and the conductive layer 112B3. The conductive film 112f3 can be processed in the same way as the conductive film 112f. In Figure 44B, the boundaries between conductive layer 112R1 and conductive layer 112R2, the boundaries between conductive layer 112B1 and conductive layer 112B2, and the boundaries between conductive layer 112B2 and conductive layer 112B3 are indicated by dotted lines. The same notation will be used in subsequent drawings. 【0504】 As described above, the film thicknesses of conductive layer 112R, conductive layer 112G, and conductive layer 112B can be made different. In this example, conductive layer 112B is made the thickest and conductive layer 112G is made the thinnest among conductive layer 112R, conductive layer 112G, and conductive layer 112B, but the present invention is not limited to this, and the film thicknesses of conductive layer 112R, conductive layer 112G, and conductive layer 112B can be set as appropriate. For example, conductive layer 112R may be made the thickest and conductive layer 112B the thinnest among conductive layer 112R, conductive layer 112G, and conductive layer 112B. 【0505】 Although the thickness of conductive layer 112C is assumed to be equal to the thickness of conductive layer 112G, the present invention is not limited to this. For example, the thickness of conductive layer 112C may be thicker than the thickness of conductive layer 112G. For example, when processing conductive film 112f3, as well as when processing conductive film 112f2, a conductive film may be left to cover the top and side surfaces of conductive layer 111C. In this case, the thickness of conductive layer 112C can be made equal to, for example, the thickness of conductive layer 112R. Furthermore, when processing any of conductive film 112f1, conductive film 112f2, and conductive film 112f3, a conductive film may be left to cover the top and side surfaces of conductive layer 111C. In this case, the thickness of conductive layer 112C can be made equal to, for example, the thickness of conductive layer 112B. 【0506】 Next, as shown in Figure 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. Subsequently, 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 order on the EL film 113f, the conductive layer 112C, and the insulating layer 105. 【0507】 Next, as shown in Figure 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, positions overlapping with the conductive layer 112G, and positions overlapping with the conductive layer 112B. It is also preferable to provide the resist mask 190 at a position overlapping with the conductive layer 112C. Furthermore, as shown in the cross-sectional view between B1 and B2 in Figure 44C, it is preferable to provide the resist mask 190 so as to cover from the edge of the EL film 113f to the edge of the conductive layer 112C on the EL film 113f side. 【0508】 Next, as shown in Figures 44C and 44D, a portion of the mask film 119f is removed using the resist mask 190 to form a mask layer 119. The mask layer 119 remains on the conductive layer 112R, conductive layer 112G, conductive layer 112B, and conductive layer 112C. After that, the resist mask 190 is removed. Subsequently, a portion of the mask film 118f is removed using the mask layer 119 as a mask to form a mask layer 118. 【0509】 Next, as shown in Figures 44C and 44D, the EL film 113f is processed to form the EL layer 113. For example, the mask layer 119 and the mask layer 118 are used as masks to remove a portion of the EL film 113f and form the EL layer 113. 【0510】 As a result, as shown in Figure 44D, the laminated structure of the EL layer 113, mask layer 118, and mask layer 119 remains on the conductive layer 112R, conductive layer 112G, and conductive layer 112B, respectively. Furthermore, between B1 and B2, the mask layer 118 and 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】 Next, the same process as shown in Figures 26C to 31B is carried out. Subsequently, a colored layer 132R, a colored layer 132G, and a colored layer 132B are formed on the protective layer 131. Then, by laminating the substrate 120 onto the colored layer 132 using the resin layer 122, a display device having the configuration shown in Figure 19A and the configuration shown in Figure 18A can be manufactured. 【0512】 As described above, the display device 100 having the configuration shown in Figure 19A can be manufactured by performing the formation and processing of the EL film 113f, mask film 118f, and mask film 119f in a single step, without the need to perform the process for each color. Therefore, the manufacturing process of the display device 100 can be simplified. Consequently, the manufacturing cost of the display device 100 can be reduced, making the display device 100 a low-cost display device. 【0513】 [Example of manufacturing method 5] In the following section, examples of methods for manufacturing a display device 100 having the configuration shown in Figure 21A and the configuration shown in Figure 18C will be explained with reference to the drawings. Note that the explanation will mainly focus on methods different from those described in Figures 32A to 32C and Figures 33A to 37B, while methods identical to those described above will be omitted as appropriate. 【0514】 First, the same process as shown in Figures 32A to 32C is performed. As a result, conductive layers 111R, 111G, 111B, and 111C are formed on the plug 106 and the insulating layer 105, as shown in Figure 45A. In addition, a conductive film 112f is formed on conductive layer 111R, conductive layer 111G, conductive layer 111B, conductive layer 111C, and the insulating layer 105. 【0515】 Next, as shown in Figure 45B, an EL film 113f, which will later become the EL layer 113, is formed on the conductive film 112f. Subsequently, 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 order on the EL film 113f and the conductive film 112f. 【0516】 Next, as shown in Figure 45B, a resist mask 190 is formed on the mask film 119f. The resist mask 190 is provided in positions overlapping with the conductive layer 111R, the conductive layer 111G, and the conductive layer 111B. It is also preferable to provide the resist mask 190 in positions overlapping with the conductive layer 111C. Furthermore, as shown in the cross-sectional view between B1 and B2 in Figure 45B, it is preferable to provide the resist mask 190 so as to cover from the edge of the EL film 113f to the edge of the conductive layer 111C on the EL film 113f side. 【0517】 Next, as shown in Figures 45B and 45C, a portion of the mask film 119f is removed using the resist mask 190 to form a mask layer 119. The mask layer 119 remains on the conductive layer 111R, conductive layer 111G, conductive layer 111B, and conductive layer 111C. After that, the resist mask 190 is removed. Subsequently, the mask layer 119 is used as a mask to remove a portion of the mask film 118f to form a mask layer 118. 【0518】 Next, as shown in Figures 45B and 45C, the EL film 113f is processed to form the EL layer 113. For example, the mask layer 119 and the mask layer 118 are used as masks to remove a portion of the EL film 113f and form the EL layer 113. 【0519】 As a result, as shown in Figure 45C, the laminated structure of the EL layer 113, mask layer 118, and mask layer 119 remains on the conductive layer 111R, conductive layer 111G, and conductive layer 111B, respectively. Furthermore, between B1 and B2, the mask layer 118 and mask layer 119 can be provided so as to cover from the edge of the EL layer 113 to the edge of the conductive layer 111C on the EL layer 113 side. 【0520】 Next, the same process as shown in Figures 34C to 37B is carried out. Subsequently, a colored layer 132R, a colored layer 132G, and a colored layer 132B are formed on the protective layer 131. Then, by laminating the substrate 120 onto the colored layer 132 using the resin layer 122, a display device having the configuration shown in Figure 21A and the configuration shown in Figure 18C can be manufactured. 【0521】 As described above, the display device 100 having the configuration shown in Figure 21A can be manufactured by performing the formation and processing of the EL film 113f, mask film 118f, and mask film 119f in a single step, without the need to perform the process for each color. Therefore, the manufacturing process of the display device 100 can be simplified. Consequently, the manufacturing cost of the display device 100 can be reduced, making the display device 100 a low-cost display device. 【0522】 This embodiment can be combined with other embodiments as appropriate. Furthermore, if multiple configuration examples are shown within a single embodiment in this specification, these configuration examples can be combined as appropriate. 【0523】 (Embodiment 2) In this embodiment, an example of a light-emitting element configuration that can be used in a display device according to one aspect of the present invention, specifically an example of a light-emitting element configuration with a tandem structure, will be described. 【0524】 Figure 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 a 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 a pair of electrodes. 【0526】 Electrode 501 functions as a pixel electrode and is provided for each light-emitting element. Electrode 502 functions as a common electrode and is provided in common to multiple light-emitting elements. 【0527】 As shown in Figure 46A, the light-emitting unit 512R_1 has layers 521, 522, 523R, and 524. The light-emitting unit 512R_2 has layers 522, 523R, and 524. The light-emitting element 550R has layer 525 between the light-emitting unit 512R_2 and the electrode 502. Note that layer 525 can also be considered as part of the light-emitting unit 512R_2. 【0528】 When electrode 501 functions as the anode and electrode 502 functions as the cathode, layer 521 has, for example, a layer containing a material with high hole injection properties (hole injection layer). Layer 522 has, for example, one or both of a layer containing a material with high hole transport properties (hole transport layer) and a layer containing a material with high electron blocking properties (electron blocking layer). Layer 524 has, for example, one or both of a layer containing a material with high electron transport properties (electron transport layer) and a layer containing a material with high hole blocking properties (hole blocking layer). Layer 525 has, for example, a layer containing a material with high electron injection properties (electron injection layer). 【0529】 When electrode 501 functions as the cathode and electrode 502 functions as the anode, for example, layer 521 has an electron injection layer, layer 522 has one or both of an electron transport layer and a hole blocking layer, layer 524 has one or both of a hole transport layer and an electron blocking layer, and layer 525 has a hole injection layer. 【0530】 Note that layer 522, light-emitting layer 523R, and layer 524 may have the same configuration (material, film thickness, etc.) in light-emitting unit 512R_1 and light-emitting unit 512R_2, or they may have different configurations. 【0531】 Note that in Figure 46A, layers 521 and 522 are shown separately, but this is not the only way. For example, if layer 521 has the functions of both a hole injection layer and a hole transport layer, or if layer 521 has the functions of both an electron injection layer and an electron transport layer, then layer 522 may be omitted. 【0532】 When fabricating a tandem light-emitting device, two light-emitting units are stacked with a charge generation layer 531 in between. The charge generation layer 531 has at least a charge generation region. When a voltage is applied between electrode 501 and electrode 502, the charge generation layer 531 has the function of injecting electrons into one of the light-emitting units 512R_1 and 512R_2, and injecting holes into the other. 【0533】 The light-emitting layer 523R of the light-emitting element 550R has a light-emitting material that emits red light, the light-emitting layer 523G of the light-emitting element 550G has a light-emitting material that emits green light, and the light-emitting layer 523B of the light-emitting element 550B has a light-emitting material that emits blue light. 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 the same as those of the light-emitting element 550R. 【0534】 Layers 521, 522, 524, and 525 may each have the same configuration (material, film thickness, etc.) for two or more or all colored light-emitting elements, or they may have different configurations for all colored light-emitting elements. 【0535】 In this specification, a configuration in which multiple light-emitting units, such as light-emitting units 550R, 550G, and 550B, are connected in series via a charge generation layer 531 is referred to as a tandem structure. On the other hand, a configuration having one light-emitting unit between a pair of electrodes is referred to as a single structure. The tandem structure may also be called a stacked structure. By using a tandem structure, it is possible to create a light-emitting element that can emit high brightness. Furthermore, compared to a single structure, the tandem structure can reduce the current required to obtain the same brightness, thereby improving the reliability of the light-emitting element. 【0536】 One embodiment of the present invention, the display device 500, employs a tandem-structured light-emitting element and can be said to have an SBS structure. Therefore, it can combine the advantages of both the tandem structure and the SBS structure. The light-emitting element in the display device 500 shown in Figure 46A has a structure in which two light-emitting units are formed in series, and may therefore be called a two-stage tandem structure. In the two-stage tandem-structured light-emitting element 550R shown in Figure 46A, a second light-emitting unit having a red light-emitting layer is stacked on top of a first light-emitting unit having a red light-emitting layer. Similarly, in the two-stage tandem-structured light-emitting element 550G shown in Figure 46A, a second light-emitting unit having a green light-emitting layer is stacked on top of a first light-emitting unit having a green light-emitting layer, and in the light-emitting element 550B, a second light-emitting unit having a blue light-emitting layer is stacked on top of a first light-emitting unit having a blue light-emitting layer. 【0537】 Figure 46B shows a modified version of the display device 500 shown in Figure 46A. In the display device 500 shown in Figure 46B, laye...

Claims

[Claim 1] A first conductive layer and a second conductive layer are formed. A third conductive layer is formed that covers the upper and side surfaces of the first conductive layer and has a lower reflectivity to visible light than the first conductive layer, and a fourth conductive layer is formed that covers the upper and side surfaces of the second conductive layer and has a lower reflectivity to visible light than the second conductive layer. A first EL film is formed on the third conductive layer and the fourth conductive layer. A first mask film is formed on the first EL film. The first EL film and the first mask film are processed to form a first EL layer on the third conductive layer and a first mask layer on the first EL layer, and the fourth conductive layer is exposed. A second EL film is formed on the first mask layer and the fourth conductive layer. A second mask film is formed on the second EL film. The second EL film and the second mask film are processed to form a second EL layer on the fourth conductive layer and a second mask layer on the second EL layer, and the first mask layer is exposed. An insulating film is 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. Using the insulating layer as a mask, an etching process is performed 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, comprising forming a common electrode on the first EL layer, the second EL layer, and the insulating layer. [Claim 2] In claim 1, A method for manufacturing a display device, comprising: performing a hydrophobic treatment on the third conductive layer and the fourth conductive layer after the formation of the third conductive layer and the fourth conductive layer, and before the formation of the first EL film. [Claim 3] In claim 2, A method for manufacturing a display device, comprising performing the hydrophobic treatment by fluorine modification on the third conductive layer and the fourth conductive layer. [Claim 4] In any one of claims 1 to 3, The etching process is performed by wet etching, in a method for manufacturing a display device.

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