Display device and method for manufacturing display device

Abstract

A display device with high display quality is provided. The display device includes a first pixel and a second pixel disposed adjacent to the first pixel. The first pixel includes a first pixel electrode, a first EL layer on the first pixel electrode, and a common electrode on the first EL layer. The second pixel includes a second pixel electrode, a second EL layer on the second pixel electrode, and a common electrode on the second EL layer. The side surfaces of the first pixel electrode and the second pixel electrode each have a tapered shape, and the cone angle of the tapered shape is less than 90°. The display device has a region where the distance between the first pixel electrode and the second pixel electrode is less than 1 μm.

Description

[Technical Field]

[0001] One embodiment of the present invention relates to a display device. Another embodiment of the present invention relates to a method for manufacturing a display device.

[0002] Note that one embodiment of the present invention is not limited to the above-described technical fields. Examples of technical fields for one embodiment of the present invention disclosed in this specification include semiconductor devices, display devices, light-emitting devices, energy storage devices, memory devices, electronic devices, lighting equipment, input devices, input / output devices, driving methods for these devices, or manufacturing methods for these devices. A semiconductor device refers to any device capable of operating by utilizing the characteristics of a semiconductor. [Previous Technology]

[0003] In recent years, there has been a demand for high-definition display panels. Devices requiring high-definition display panels include smartphones, tablets, and laptops. Additionally, fixed display devices such as televisions and monitors are also being required to achieve higher resolutions. Among the devices with the greatest demand for high definition are those used in virtual reality (VR) or augmented reality (AR) applications.

[0004] In addition, typical examples of display devices that can be applied to display panels include liquid crystal display devices, light-emitting devices having light-emitting elements such as organic EL (Electro Luminescence) elements or light-emitting diodes (LEDs), and electronic paper that displays by electrophoresis or the like.

[0005] For example, the basic structure of an organic EL element is a structure in which a layer containing a luminescent organic compound is sandwiched between a pair of electrodes. By applying a voltage to the element, light emission from the luminescent organic compound can be obtained. Since display devices using the above-mentioned organic EL elements do not require a backlight source as needed for liquid crystal display devices, thin, lightweight, high-contrast, and low-power display devices can be realized. For example, Patent Document 1 discloses an example of a display device using an organic EL element.

[0006] Patent document 2 discloses a display device for VR that uses organic EL devices.

[0007] [Patent Document 1] Japanese Patent Application Publication No. 2002-324673 [Patent Document 2] International Publication No. 2018 / 087625 [Summary of the Invention]

[0008] One objective of one embodiment of the present invention is to provide a display device with high display quality. One objective of one embodiment of the present invention is to provide a display device with high reliability. One objective of one embodiment of the present invention is to provide a display device with low power consumption. One objective of one embodiment of the present invention is to provide a display device that easily achieves high definition. One objective of one embodiment of the present invention is to provide a display device that combines high display quality and high definition. One objective of one embodiment of the present invention is to provide a display device with high contrast.

[0009] One objective of one embodiment of the present invention is to provide a display device or a method for manufacturing a display device having a novel structure. Another objective of one embodiment of the present invention is to provide a method for manufacturing the aforementioned display device with high yield. Finally, another objective of one embodiment of the present invention is to improve at least one of the problems of the prior art.

[0010] Note that the description of these objectives does not preclude the existence of other objectives. Note that one embodiment of the present invention does not need to achieve all of the above objectives. In addition, objectives other than those described above can be derived from the description in the specification, drawings, claims, etc.

[0011] One embodiment of the present invention is a display device, which includes a first pixel and a second pixel disposed adjacent to the first pixel. The first pixel includes a first pixel electrode, a first EL layer on the first pixel electrode and a common electrode on the first EL layer. The second pixel includes a second pixel electrode, a second EL layer on the second pixel electrode and a common electrode on the second EL layer. The side surfaces of the first pixel electrode and the second pixel electrode each have a conical shape, and the cone angle of the conical shape is less than 90°. The display device has a region where the distance between the first pixel electrode and the second pixel electrode is less than 1 μm.

[0012] In addition, in the above structure, it is preferred to adopt the following structure: it further includes a first insulating layer and a second insulating layer on the first insulating layer, the first insulating layer contains inorganic material, the second insulating layer contains organic material, and the second insulating layer overlaps with the side of the first EL layer and the side of the second EL layer through the first insulating layer.

[0013] Alternatively, in the above structure, the following structure may also be adopted: the first insulating layer covers the side of the first pixel electrode, the side of the first EL layer, the side of the second pixel electrode, and the side of the second EL layer.

[0014] Alternatively, the structure described above can also be as follows: both the first pixel electrode and the second pixel electrode include a first conductive layer, a second conductive layer on the first conductive layer, a third conductive layer on the second conductive layer, and a fourth conductive layer on the third conductive layer. The second conductive layer is reflective, the first conductive layer and the third conductive layer have the function of protecting the second conductive layer, the work function of the fourth conductive layer is greater than that of the third conductive layer, and the third conductive layer and the fourth conductive layer are transparent.

[0015] Additionally, in the above structure, the first conductive layer may contain titanium. Furthermore, in the above structure, the second conductive layer may contain aluminum. Furthermore, in the above structure, the third conductive layer may contain titanium oxide. Furthermore, in the above structure, the fourth conductive layer may contain an oxide selected from one or more of indium, tin, zinc, gallium, titanium, aluminum, and silicon.

[0016] Alternatively, in the above structure, the following structure may also be adopted: the first pixel includes a common layer disposed between the first EL layer and the common electrode, and the second pixel includes a common layer disposed between the second EL layer and the common electrode.

[0017] Another embodiment of the present invention is a method for manufacturing a display device, comprising the following steps in manufacturing a plurality of pixel electrodes including a first conductive layer, a second conductive layer, a third conductive layer and a fourth conductive layer: sequentially depositing a first conductive film, a second conductive film, a third conductive film and a fourth conductive film on an insulating layer; forming a photoresist mask on the fourth conductive film; processing the photoresist mask into a conical shape by heat treatment; processing the fourth conductive film into a fourth conductive layer by wet etching; processing the third conductive film and the second conductive film into a third conductive layer and a second conductive layer by a first dry etching; and processing the first conductive film into a first conductive layer by a second dry etching and further etching the second conductive layer and the third conductive layer, wherein the etching rate of the photoresist mask in the second dry etching is greater than the etching rate of the third conductive layer, such that the distance between the first conductive layer included in one of the plurality of pixel electrodes and the first conductive layer included in another of the plurality of pixel electrodes is less than 1 μm.

[0018] Furthermore, in the above structure, it is preferable to use chlorine-based gas and fluorine-based gas in the second dry etching. Also, in the above structure, it is preferable that the bias power in the second dry etching is greater than that in the first dry etching.

[0019] Alternatively, in the above structure, a structure in which heat treatment is performed in an oxygen-containing atmosphere after the deposition of the third conductive film can also be adopted.

[0020] Alternatively, in the above structure, the first conductive film and the third conductive film may contain titanium. Alternatively, in the above structure, the second conductive film may contain aluminum. Alternatively, in the above structure, the fourth conductive film may contain an oxide selected from one or more of indium, tin, zinc, gallium, titanium, aluminum, and silicon.

[0021] According to one embodiment of the present invention, a display device with high display quality can be provided. According to one embodiment of the present invention, a display device with high reliability can be provided. According to one embodiment of the present invention, a display device with low power consumption can be provided. According to one embodiment of the present invention, a display device that easily achieves high definition can be provided. According to one embodiment of the present invention, a display device that combines high display quality and high definition can be provided. According to one embodiment of the present invention, a display device with high contrast can be provided.

[0022] According to one embodiment of the present invention, a display device having a novel structure or a method for manufacturing a display device can be provided. According to one embodiment of the present invention, a method for manufacturing the above-described display device with high yield can be provided. According to one embodiment of the present invention, at least one of the problems of the prior art can be improved.

[0023] Note that the description of these effects does not preclude the existence of other effects. Note that one embodiment of the present invention does not need to have all the above-described effects. In addition, effects other than those described above can be derived from the description in the specification, drawings, claims, etc.

Implementation Method

[0025] The embodiments will now be described with reference to the drawings. Note that the embodiments can be implemented in many different ways, and those skilled in the art will readily understand that the methods and details can be varied in many ways without departing from the spirit and scope of the invention. Therefore, the invention should not be construed as being limited to the contents described in the following embodiments.

[0026] Note that in the inventive structure described below, the same element symbols are used in different figures to represent the same parts or parts with the same function, and repeated descriptions are omitted. In addition, when parts with the same function are represented, the same shading lines are sometimes used without additional element symbols.

[0027] Note that in the various figures described in this specification, the size of each component, the thickness of a layer, or the area are sometimes exaggerated for clarity. Therefore, the present invention is not limited to the dimensions shown in the figures.

[0028] The ordinal numbers such as “first” and “second” used in this specification are appended to avoid confusion of components, and are not intended to limit the number of components.

[0029] In this specification and the like, the terms "film" and "layer" may be interchanged. For example, sometimes "conductive layer" or "insulating layer" may be replaced with "conductive film" or "insulating film" respectively.

[0030] Note that in this specification, the EL layer refers to a layer disposed between a pair of electrodes of a light-emitting element and including at least a light-emitting material (also called a light-emitting layer) or a stack including a light-emitting layer.

[0031] In this specification and the like, a display panel in one embodiment of a display device refers to a panel capable of displaying (outputting) images, etc., on a display surface. Therefore, a display panel is one embodiment of an output device.

[0032] In this specification, the structure on which connectors such as FPC (Flexible Printed Circuit) or TCP (Tape Carrier Package) are mounted on the substrate of the display panel, or the structure on which ICs are directly mounted on the substrate in the manner of COG (Chip On Glass), is sometimes referred to as a display panel module or display module, or simply as a display panel, etc.

[0033] The light-emitting element of one embodiment of the present invention may also include a layer comprising a material with high hole injection capacity, a material with high hole transport capacity, a material with high electron transport capacity, a material with high electron injection capacity, a bipolar material, etc.

[0034] Furthermore, the light-emitting layer and the layer containing substances with high hole injection capacity, high hole transport capacity, high electron transport capacity, high electron injection capacity, bipolar substances, etc., may respectively contain inorganic compounds or polymeric compounds (oligomers, dendritic polymers, or polymers, etc.) such as quantum dots. For example, by using quantum dots in the light-emitting layer, they can also be used as light-emitting materials.

[0035] As quantum dot materials, colloidal quantum dot materials, alloy-type quantum dot materials, core-shell quantum dot materials, and nucleus-type quantum dot materials can be used. Alternatively, materials containing elements from Groups 12 and 16, 13 and 15, and 14 and 16 can also be used. Or, quantum dot materials containing elements such as cadmium, selenium, zinc, sulfur, phosphorus, indium, tellurium, lead, gallium, arsenic, and aluminum can be used.

[0036] Embodiment 1 In this embodiment, an example of the structure of a display device according to an embodiment of the present invention and an example of a method for manufacturing the display device will be described.

[0037] One embodiment of the present invention is a display device including light-emitting elements (also called light-emitting devices). The display device includes at least two light-emitting elements that emit light of different colors. Each light-emitting element includes a pair of electrodes and an EL layer between the pair of electrodes. As light-emitting elements, electroluminescent elements such as organic EL elements and inorganic EL elements can be used. In addition, light-emitting diodes (LEDs) can also be used. In one embodiment of the present invention, the light-emitting element is preferably an organic EL element (organic electroluminescent element). Two or more light-emitting elements emitting different colors each include an EL layer containing different materials. For example, by including three light-emitting elements that respectively emit red (R), green (G), or blue (B) light, a full-color display device can be realized.

[0038] Here, it is known that when EL layers are formed between light-emitting elements emitting different colors, the EL layers are formed by vapor deposition using a shadow mask such as a metal mask or an FMM (Fine Metal Mask). In this specification, devices using a metal mask or an FMM are sometimes referred to as MM (metal mask) structures.

[0039] However, this method is not easy to achieve high resolution and high aperture ratio because the shape and position of the island-shaped organic film differ from the design due to various factors such as the precision of the metal mask, misalignment between the metal mask and the substrate, bending of the metal mask, and vapor scattering, which can cause the outline of the deposited film to expand. In addition, during the vapor deposition process, particles are sometimes generated due to the material adhering to the metal mask. These particles may cause poor patterning of the light-emitting element. In addition, short circuits may occur due to particles. Furthermore, a cleaning process for the material adhering to the metal mask is required. Therefore, resolution (also known as pixel density) is improved by analogy by using special pixel arrangement methods such as Pentile arrangement.

[0040] In one embodiment of the present invention, the EL layer is processed into a fine pattern without using a shadow mask such as a metal mask. Note that in this specification, a display device manufactured using a metal mask or FMM (Fine Metal Mask) is sometimes referred to as a display device with an MM (Metal Mask) structure. Additionally, in this specification, a display device manufactured without using a metal mask or FMM is sometimes referred to as a display device with an MML (Metal Mask Less) structure. By forming with an MML structure, a display device with high resolution and high aperture ratio, which was previously difficult to achieve, can be realized. Furthermore, since the EL layers can be manufactured separately, a display device with very vivid colors, high contrast, and high display quality can be realized. Furthermore, by providing a sacrificial layer on the EL layer, damage to the EL layer during the manufacturing process of the display device can be reduced, thereby improving the reliability of the light-emitting device. Because an MML structure display device is manufactured without using a metal mask, its design flexibility in pixel configuration and pixel shape is greater than that of an MM structure display device. Note that in this specification, the sacrificial layer may also be referred to as a mask layer.

[0041] For simplicity, the case of fabricating EL layers for two different colors of light-emitting elements will be described here. First, a first EL film and a first sacrificial film are formed by stacking over pixel electrodes. Next, a photoresist mask is formed on the first sacrificial film. Then, a portion of the first sacrificial film and a portion of the first EL film are etched using the photoresist mask to form the first EL layer and the first sacrificial layer on the first EL layer. Note that in this specification, the sacrificial film may also be referred to as a mask film.

[0042] Next, a second EL film and a second sacrificial film are laminated to form a second EL layer and a second sacrificial layer on the second EL layer. Then, a portion of the second sacrificial film and a portion of the second EL film are etched using a photoresist mask to form a second EL layer and a second sacrificial layer on the second EL layer. Through the above steps, a first EL layer and a second EL layer can be formed respectively. Finally, the first sacrificial layer and the second sacrificial layer are removed to form a common electrode, thereby forming light-emitting elements of two colors respectively.

[0043] In addition, by repeatedly performing the above process, EL layers of light-emitting elements with three or more colors can be formed respectively, thereby realizing a display device including light-emitting elements with three or four or more colors.

[0044] When EL layers of different colors are adjacent to each other, it is difficult to set the spacing between adjacent EL layers or adjacent pixel electrodes to less than 10 μm, for example, in the formation method using a metal mask. However, in the above method, it can be reduced to less than 3 μm, less than 2 μm, or less than 1 μm. For example, by using an LSI exposure apparatus, the spacing can also be reduced to less than 500 nm, less than 200 nm, less than 100 nm, or even less than 50 nm. As a result, the area of ​​non-light-emitting regions that may exist between two light-emitting elements can be significantly reduced, and the aperture ratio can be close to 100%. For example, aperture ratios of 50% or more, 60% or more, 70% or more, 80% or more, or even 90% or more but less than 100% can be achieved.

[0045] Furthermore, the pattern (or feature size) of the EL layer itself is significantly reduced compared to the case where a metal mask is used. Additionally, when forming the EL layer separately using a metal mask, the thickness of the EL layer differs between the center and ends, thus reducing the effective area usable as a light-emitting region relative to the area of ​​the EL layer. On the other hand, in the above manufacturing method, the EL layer is formed by processing a film deposited to a uniform thickness, allowing for a uniform EL layer thickness. Even with fine patterns, almost the entire EL layer can be used as a light-emitting region. Therefore, the above manufacturing method achieves both high resolution and high aperture ratio.

[0046] Thus, by means of the above manufacturing method, a display device in which micro-light-emitting elements are integrated can be realized, and for example, without the need to improve the clarity by analogy with a special pixel arrangement such as the Pentile method, a display device with a clarity of 500ppi or more, 1000ppi or more, or 2000ppi or more, or even 3000ppi or more, or even 5000ppi or more can be realized by using a so-called stripe arrangement in which R, G, and B are all arranged in one direction.

[0047] As described above, when the distance between adjacent pixel electrodes is small (e.g., the distance between pixel electrodes is 1 μm or less), recesses with a large aspect ratio are formed between adjacent pixel electrodes. If an EL layer is formed with such recesses, wall-like structures may be formed between adjacent pixel electrodes. Furthermore, when multiple EL layers with different emission colors are formed, multiple wall-like structures are formed between adjacent pixel electrodes, and corrugated structures are formed. In particular, this tendency is more pronounced when the sides of the pixel electrodes are approximately perpendicular.

[0048] If a common layer and a common electrode are provided with a corrugated tubular structure formed between adjacent pixel electrodes, the coverage of the common layer and the common electrode will be reduced, and there is a concern that the common layer and the common electrode may be disconnected. In addition, if the common layer and the common electrode are thinned, there is a concern that the resistance will increase.

[0049] In one embodiment of the present invention, in pixel electrodes that are close to each other, by making the side surface of the pixel electrode tapered, the recess formed between the pixel electrodes can be enlarged. This suppresses the formation of wall-like structures between adjacent pixel electrodes during EL layer formation. Therefore, a common layer and a shared electrode can be provided without corrugated structures existing between adjacent pixel electrodes. Thus, by depositing the common layer and the shared electrode with high coverage, the display quality of the high-definition display device can be improved.

[0050] Note that in this specification, a tapered shape refers to a shape in which at least a portion of the side surface of a component is inclined relative to the bottom surface or substrate surface of the component. For example, it is preferred to have an area where the angle (also called the cone angle) formed by the inclined side surface and the bottom surface or substrate surface of the component is less than 90°.

[0051] Furthermore, in one embodiment of the present invention, by providing a first insulating layer comprising an organic material between adjacent EL layers, the unevenness of the surface on which the common electrode is disposed can be reduced. Therefore, the coverage of the common layer and the common electrode between adjacent EL layers can be improved, and good conductivity of the common layer and the common electrode can be achieved. In addition, short circuits between the common electrode or the common layer and the pixel electrode can be suppressed. Thus, the display quality of the high-definition display device can be further improved.

[0052] Furthermore, in one embodiment of the present invention, a second insulating layer comprising an inorganic material is provided between a first insulating layer comprising an organic material and an EL layer. Here, the second insulating layer is barrier to at least one of oxygen and moisture. By using this second insulating layer to separate the first insulating layer from the EL layer, oxygen, moisture, or their constituent elements can be suppressed from entering the interior from the side of the EL layer, thus enabling a display device with high reliability.

[0053] Furthermore, a display device according to one embodiment of the present invention can employ a structure without an insulating material covering the ends of the pixel electrodes. In other words, a structure without an insulating material between the pixel electrodes and the EL layer can be adopted. By employing this structure, light emission from the EL layer can be effectively extracted, resulting in minimal viewing angle dependence. For example, in a display device according to one embodiment of the present invention, the viewing angle (the maximum angle at which a certain contrast is maintained when viewing the screen from an oblique angle) can be in the range of 100° or more and less than 180°, preferably 150° or more and less than 170°. In addition, the above-mentioned viewing angle can be used in all directions. By employing a display device according to one embodiment of the present invention, viewing angle dependence is improved, and image visibility can be improved.

[0054] Note that when forming a display device using a metal mask or a high-precision metal mask, there are sometimes limitations on the structure of the pixel configuration. Here, the MM structure will be explained.

[0055] As a metal mask (MM) structure, during EL deposition, a metal mask (also called a metal mask or fMM) with an opening is disposed opposite the substrate so that EL is deposited in the desired area. Then, EL deposition is performed on the fMM to deposit EL in the desired area. When the substrate size during EL deposition is larger, the size of the fMM becomes larger, and its weight also increases. In addition, during EL deposition, heat is applied to the fMM, so the fMM sometimes deforms. Alternatively, there are methods such as applying a certain tensile force to the fMM during EL deposition, so the weight and strength of the fMM are important parameters.

[0056] Therefore, when using an FMM (Focused Mirror Model) to design a pixel configuration structure, the aforementioned parameters must be considered, and research must be conducted under certain limitations. On the other hand, the display device of one embodiment of the present invention is manufactured using an MML (Multi-Level Model) structure, thus exhibiting the following excellent effect: compared to the MM (Multi-Level Model) structure, the pixel configuration structure is more flexible. Furthermore, this structure is very suitable for flexible devices, for example, and either or both of the pixels and the driving circuit can be configured in various ways.

[0057] Hereinafter, more specific structural examples and manufacturing method examples of a display device according to one embodiment of the present invention will be described with reference to drawings.

[0058] [Structural Example] FIG1A shows a top view of a display device 100 according to an embodiment of the present invention. The display device 100 includes a plurality of red light-emitting elements 110R, a plurality of green light-emitting elements 110G, and a plurality of blue light-emitting elements 110B on a substrate 101 including semiconductor circuits. In FIG1A, the symbols R, G, and B are attached to the light-emitting areas of each light-emitting element for simple distinction. Hereinafter, the light-emitting elements 110R, 110G, and 110B are sometimes collectively referred to as light-emitting elements 110.

[0059] Light-emitting elements 110R, 110G, and 110B are all arranged in a matrix. As shown in Figure 1A, pixel 103 shows a so-called striped arrangement of light-emitting elements of the same color arranged in one direction. Note that the arrangement of the light-emitting elements is not limited to this; arrangements such as Delta arrangement, zigzag arrangement, and Pentile arrangement can also be used.

[0060] As light-emitting elements 110R, 110G, and 110B, it is preferable to use light-emitting elements such as OLED (Organic Light Emitting Diode) or QLED (Quantum-dot Light Emitting Diode). Examples of light-emitting materials contained in the light-emitting elements include fluorescent materials, phosphorescent materials, inorganic compounds (quantum dot materials, etc.), and materials exhibiting thermally activated delayed fluorescence (TADF) materials.

[0061] Figure 1B is a cross-sectional view corresponding to the dashed lines A1-A2 and C1-C2 in Figure 1A, and Figure 1C is a cross-sectional view corresponding to the dashed lines B1-B2.

[0062] FIG1B shows cross-sections of light-emitting elements 110R, 110G, and 110B. Light-emitting element 110R includes a pixel electrode 111R, an EL layer 112R, a common layer 114, and a common electrode 113. Light-emitting element 110G includes a pixel electrode 111G, an EL layer 112G, a common layer 114, and a common electrode 113. Light-emitting element 110B includes a pixel electrode 111B, an EL layer 112B, a common layer 114, and a common electrode 113. Additionally, insulating layers 131 (insulating layers 131a and 131b) are provided embedded between the light-emitting elements. Furthermore, a protective layer 121 is provided on the common electrode 113. Note that, hereinafter, pixel electrodes 111R, 111G, and 111B are sometimes collectively referred to as pixel electrode 111. In addition, EL layer 112R, EL layer 112G and EL layer 112B are sometimes collectively referred to as EL layer 112.

[0063] Additionally, FIG. 2A shows an enlarged view of the area surrounded by the rectangle with dotted lines in FIG. 1B. FIG. 2B also shows an enlarged view of the area surrounded by the rectangle with dotted lines around the pixel electrode 111R in FIG. 2A. FIG. 2A and FIG. 2B show the insulating layer 101a disposed on the top surface of the substrate 101 including the semiconductor circuitry beneath the pixel electrode 111. Note that in this specification, etc., for convenience, the thickness of layers and films is sometimes described as thick in the non-enlarged drawings. Furthermore, in the enlarged drawings, the distances between the components of the display device are sometimes different.

[0064] Light-emitting element 110R includes an EL layer 112R between pixel electrode 111R and common electrode 113. EL layer 112R contains a luminescent organic compound that emits light with intensity at least in the red wavelength region. Light-emitting element 110G includes an EL layer 112G between pixel electrode 111G and common electrode 113. EL layer 112G contains a luminescent organic compound that emits light with intensity at least in the green wavelength region. Light-emitting element 110B includes an EL layer 112B between pixel electrode 111B and common electrode 113. EL layer 112B contains a luminescent organic compound that emits light with intensity at least in the blue wavelength region.

[0065] In Figures 1B and 1C, a common layer 114 is disposed between the pixel electrode 111 and the common electrode 113 of the light-emitting element 110. The common layer 114 is configured as a continuous layer shared by all light-emitting elements. Preferably, the common layer 114 is disposed in contact with the top surface of the EL layer 112. Also preferably, the common electrode 113 is disposed in contact with the top surface of the common layer 114. Note that the light-emitting element 110 may also not include the common layer 114. In this case, the common electrode 113 is preferably disposed in contact with the top surface of the EL layer 112.

[0066] Additionally, FIG1A shows a connecting electrode 111C electrically connected to the common electrode 113. The connecting electrode 111C is supplied with a potential (e.g., anode potential or cathode potential) for supplying to the common electrode 113. The connecting electrode 111C is disposed outside the display area where the light-emitting elements 110R, etc., are arranged. In FIG1A, the common electrode 113 is indicated by a dashed line.

[0067] The connecting electrode 111C can be disposed along the outer periphery of the display area. For example, it can be disposed along one edge of the outer periphery of the display area, or it can be disposed across two or more edges of the outer periphery of the display area. That is, when the top surface of the display area is rectangular, the top surface shape of the connecting electrode 111C can be strip-shaped, L-shaped, "コ"-shaped (square bracket-shaped), or square-shaped, etc.

[0068] Furthermore, the C1-C2 cross section of FIG1B shows the region 130 where the connecting electrode 111C and the common electrode 113 are electrically connected. Note that FIG1B shows an example where a common layer 114 is provided between the connecting electrode 111C and the common electrode 113, but it is not limited to this; the common layer 114 may not be provided in the region 130. In the structure without the common layer 114, the connecting electrode 111C and the common electrode 113 are in contact, which can further reduce the contact resistance.

[0069] In addition, a protective layer 121 is also provided in region 130 to cover the common electrode 113.

[0070] EL layers 112R, EL layers 112G, and EL layers 112B all include a layer (light-emitting layer) containing a luminescent organic compound. In addition to the luminescent material (guest material), the light-emitting layer may also contain one or more compounds (host material, auxiliary material). As the host material or auxiliary material, one or more substances with a band gap larger than the luminescent material (guest material) can be used. Preferably, compounds that form excited-state complexes are used in combination as host and auxiliary materials. For efficient formation of excited-state complexes, it is particularly preferred to combine compounds that readily accept holes (hole-transporting materials) and compounds that readily accept electrons (electron-transporting materials).

[0071] As a light-emitting element, low molecular weight compounds or high molecular weight compounds can be used, or inorganic compounds (quantum dot materials, etc.) can be included.

[0072] In addition to the light-emitting layer, EL layer 112R, EL layer 112G and EL layer 112B may also include one or more of the following: electron injection layer, electron transport layer, hole injection layer and hole transport layer.

[0073] Pixel electrodes 111R, 111G, and 111B are all provided in each light-emitting element. Additionally, a common electrode 113 is provided as a continuous layer shared by all light-emitting elements. One of the pixel electrodes and the common electrode 113 uses a conductive film that is transparent to visible light, and the other uses a reflective conductive film. By making each pixel electrode transparent and the common electrode 113 reflective, a bottom-emitting type (bottom-emitting type) display device can be realized. Conversely, by making each pixel electrode reflective and the common electrode 113 transparent, a top-emitting type (top-emitting structure) display device can be realized. Furthermore, by making both each pixel electrode and the common electrode 113 transparent, a double-sided emitting type (double-sided emitting structure) display device can also be realized.

[0074] Preferably, the distance between adjacent pixel electrodes 111 is reduced to 3 μm or less, 2 μm or less, or 1 μm or less. For example, it is preferable to have a region between adjacent pixel electrodes 111 such that the distance between them is 1 μm or less. Furthermore, for example, by using an LSI exposure apparatus, the distance can be reduced to 500 nm or less, 200 nm or less, 100 nm or less, or even 50 nm or less. As a result, the area of ​​the non-light-emitting region that may exist between the two light-emitting elements 110 can be significantly reduced, thereby increasing the aperture ratio.

[0075] When a conductive film with visible light reflectivity is used as the pixel electrode 111, metallic materials such as aluminum, gold, platinum, silver, nickel, tungsten, chromium, titanium, tantalum, molybdenum, iron, cobalt, copper, or palladium, or alloys containing these metallic materials, can be used. Copper has high visible light reflectivity, so it is preferred. In addition, aluminum is easy to process because the electrode is easy to etch, and aluminum has high visible and near-infrared light reflectivity, so it is preferred. Furthermore, as mentioned above, by using materials such as silver or aluminum, which have high reflectivity in the overall wavelength region of visible light, as the pixel electrode 111, not only can the light extraction efficiency of the light-emitting element be improved, but color reproduction can also be improved. In addition, lanthanum, neodymium, or germanium can also be added to the above-mentioned metallic materials and alloys. In addition, alloys containing titanium, nickel, or neodymium and aluminum (aluminum alloys) can also be used. Furthermore, alloys containing copper, palladium, magnesium, and silver can also be used. Alloys containing silver and copper have high heat resistance, so they are preferred. In addition, two or more of the above-mentioned materials can be laminated.

[0076] As shown in FIG2A, when the pixel electrode 111 has a four-layer structure consisting of a conductive layer 111a, a conductive layer 111b on the conductive layer 111a, a conductive layer 111c on the conductive layer 111b, and a conductive layer 111d on the conductive layer 111c, the aforementioned conductive film with visible light reflectivity can be used as the conductive layer 111b. For example, aluminum can be used as the conductive layer 111b.

[0077] Note that when aluminum is used as the conductive layer 111b, it is preferable to use a thickness of 40 nm or more, and more preferably 70 nm or more, thereby significantly improving the reflectivity of visible light, etc.

[0078] Furthermore, in the conductive layer 111b, a conductive film that functions to protect the conductive film reflecting visible light can be provided in a manner that contacts the top surface, bottom surface, or both of the conductive film reflecting visible light. By adopting this structure, oxidation and corrosion of the conductive film reflecting visible light can be suppressed. For example, by laminating a metal film or metal oxide film in contact with an aluminum film or aluminum alloy film, oxidation can be suppressed. Furthermore, the formation of hillocks in the aluminum film or aluminum alloy film can be suppressed. Examples of materials for such metal films or metal oxide films include titanium and titanium oxide. For example, when using the structure shown in FIG2A, titanium can be used as the conductive layer 111a and titanium oxide can be used as the conductive layer 111c. By using transparent titanium oxide as the conductive layer 111c, the attenuation of visible light reflected on the conductive layer 111b in the conductive layer 111c can be suppressed.

[0079] In addition, when a conductive metal oxide with visible light transmittance is used, the metal oxide can also be formed by oxidizing the surface of the conductive material. For example, when titanium oxide is used, titanium oxide can be formed by depositing titanium using a sputtering method or the like and oxidizing the surface of the titanium.

[0080] Furthermore, the pixel electrode 111 can be used by stacking a conductive film with visible light transmittance on a conductive film with visible light reflectivity. By stacking a conductive film with visible light transmittance on a conductive film with visible light reflectivity as the pixel electrode 111, the conductive film with visible light transmittance can be used as an optical adjustment layer. As a conductive material with visible light transmittance, an oxide containing one or more of indium, tin, zinc, gallium, titanium, aluminum, and silicon can be used. For example, it is preferable to use a conductive oxide including one or more of indium oxide, indium tin oxide, indium zinc oxide, zinc oxide, zinc oxide containing gallium, titanium oxide, indium zinc oxide containing gallium, indium zinc oxide containing aluminum, indium tin oxide containing silicon, and indium zinc oxide containing silicon. By providing an oxide on the surface of the pixel electrode 111, oxidation reactions with the pixel electrode 111 can be suppressed when the EL layer 112 is formed.

[0081] Furthermore, when the pixel electrode 111 is used as the anode, it is preferable to use a conductive film with a high work function (e.g., a work function of 4.0 eV or higher). For example, when the structure shown in FIG. 2A is adopted, indium tin oxide containing silicon can be used as the conductive layer 111d. Here, the thickness of the conductive layers 111d and 111c, which have visible light transmittance, is preferably smaller than that of the conductive layer 111b. Moreover, it is even more preferable that the total thickness of the conductive layers 111d and 111c is smaller than the thickness of the conductive layer 111b.

[0082] When the pixel electrode 111 includes an optical adjustment layer, the optical path length can be adjusted. The optical path length of each light-emitting element corresponds, for example, to the total thickness of the layers disposed under the film containing the luminescent compound in the optical adjustment layer and the EL layer 112.

[0083] In light-emitting elements, by using a microcavity structure (micro-resonator structure) to make the optical path length different, light of a specific wavelength can be amplified. As a result, a display device with improved color purity can be realized.

[0084] For example, in each light-emitting element, a microcavity structure can be realized by varying the thickness of the EL layer 112. For example, a structure can be adopted in which the thickness of the EL layer 112R of the light-emitting element 110R that emits the longest wavelength light is maximized, and the thickness of the EL layer 112B of the light-emitting element 110B that emits the shortest wavelength light is minimized. Furthermore, not limited to this, the thickness of each EL layer can be adjusted considering the wavelength of the light emitted by each light-emitting element, the optical characteristics of the layers constituting the light-emitting element, and the electrical characteristics of the light-emitting element.

[0085] Furthermore, as shown in FIG2B, the side surface of the pixel electrode 111 is preferably tapered when viewed in cross-section. In this specification, a tapered shape refers to a shape in which the side surface is inclined relative to the bottom surface. Here, the side surface and the bottom surface do not necessarily need to be completely flat; they may be approximately planar with slight curvature or approximately planar with slight irregularities.

[0086] As shown in FIG2B, the angle formed by the bottom surface and the side surface of the pixel electrode 111 is set as the cone angle θ. Here, in measuring the cone angle θ, the bottom surface of the substrate 101, the top surface of the substrate 101, or the top surface of the insulating layer 101a can be used instead of the bottom surface of the pixel electrode 111. In addition, in measuring the cone angle θ, the side surface of the pixel electrode 111 can be the surface passing through the upper end of any one side surface from conductive layer 111a to conductive layer 111d and the lower end of any one side surface. For example, the surface passing through the lower end of the side surface of conductive layer 111a and the upper end of the side surface of conductive layer 111d can be used, the surface passing through the lower end of the side surface of conductive layer 111a and the upper end of the side surface of conductive layer 111c can be used, or the surface passing through the lower end of the side surface of conductive layer 111a and the upper end of the side surface of conductive layer 111a can be used.

[0087] The cone angle θ of the pixel electrode 111 is less than 90°, preferably less than 80°, more preferably less than 70°, and even more preferably less than 50°.

[0088] Additionally, as shown in FIG2B, the recess is sometimes formed in the region of the insulating layer 101a that does not overlap with the pixel electrode 111. As shown in FIG2B, the angle formed by the side surface of the recess and the extended surface including the bottom surface of the recess is set as the cone angle θ2. Similar to the cone angle θ, the cone angle θ2 is less than 90°, preferably less than 80°, more preferably less than 70°, and even more preferably less than 50°. Note that the cone angle θ2 is sometimes larger than the cone angle θ.

[0089] For example, when the side surfaces of the pixel electrodes 111 are approximately perpendicular, as shown in this embodiment, when the distance between adjacent pixel electrodes 111 is small (e.g., the distance between pixel electrodes 111 is 1 μm or less), a recess with a large aspect ratio is formed between the pixel electrodes 111. If the EL layer 112 is formed with such recesses, wall-like structures may be formed between adjacent pixel electrodes 111. Furthermore, when multiple EL layers 112 with different emission colors are formed, multiple wall-like structures are formed between the pixel electrodes 111, and a corrugated structure is formed.

[0090] If a common layer 114 and a common electrode 113 are provided with a corrugated tubular structure formed between the pixel electrodes 111, a break may occur in the common layer 114 and the common electrode 113, which will lead to a decrease in the display quality of the display device.

[0091] Conversely, in this invention, by making the side surfaces of the pixel electrodes 111 tapered, the recesses between the pixel electrodes 111 can be enlarged. This suppresses the formation of wall-like structures between the pixel electrodes 111 during the formation of the EL layer 112. Therefore, the common layer 114 and the common electrode 113 can be provided without the corrugated structure existing between the pixel electrodes 111. Thus, by depositing the common layer 114 and the common electrode 113 with high coverage, the display quality of the high-definition display device can be improved.

[0092] Note that Figures 2A and 2B show an example of a four-layer stack of conductive layers 111a to 111d for the pixel electrode 111, but structures with three or fewer layers or more layers can be used. For example, as shown in Figure 2C, a structure in which a single conductive film is used to form the pixel electrode 111 can also be used.

[0093] In addition, sometimes any one of the multiple conductive layers constituting the pixel electrode 111 has a shape that is recessed relative to the side of the pixel electrode 111.

[0094] For example, as shown in FIG3A, sometimes the conductive layer 111d has a recessed shape. When the conductive layer 111d has a shape that is significantly recessed relative to the side of the pixel electrode 111, as shown in FIG3A, it is preferable to measure the cone angle θ using the side surface other than the conductive layer 111d. For example, in the case of FIG3A, it is preferable to measure the cone angle θ using the surface passing through the lower end of the conductive layer 111a and the upper end of the conductive layer 111c as the side surface of the pixel electrode 111.

[0095] Additionally, for example, as shown in FIG3B, sometimes the conductive layers 111b and 111c also have a shape that is recessed compared to the case in FIG3A. When the distance that the conductive layers 111b and 111c are recessed relative to the side of the pixel electrode 111, as shown in FIG3B, is small, the cone angle θ can also be measured using the side surface including the conductive layers 111b and 111c. For example, in the case of FIG3B, the cone angle θ can also be measured using the surface passing through the lower end of the conductive layer 111a and the upper end of the conductive layer 111c as the side surface of the pixel electrode 111.

[0096] Additionally, for example, as shown in FIG3C, sometimes the conductive layer 111b has a shape that is recessed relative to the conductive layers 111a and 111c.

[0097] Furthermore, as shown in Figures 1B and 1C, the EL layer 112 can also be formed only on the flat portion of the pixel electrode 111 and not across the end of the pixel electrode 111. By adopting such a structure, the breakage of the EL layer 112 due to the step of the pixel electrode 111 can be suppressed. In addition, further breakage in the common layer 114 and the common electrode 113 due to such breakage can be prevented. Here, the lower end of the side of the EL layer 112 is preferably roughly aligned with the upper end of the side of the pixel electrode 111. Thus, almost the entire pixel electrode 111 can function as a light-emitting element.

[0098] Note that the present invention is not limited to the above-described structure. As shown in Figures 5A to 5C, a structure in which the top and side surfaces of the pixel electrode 111 are covered by the EL layer 112 can also be used. In this case, the side end of the EL layer 112 is located outside the side end of the pixel electrode 111. In addition, the area of ​​the EL layer 112 that is not in contact with the pixel electrode 111 is in contact with the top surface of the insulating layer 101a. Furthermore, unlike the structures shown in Figures 1B and 1C, the insulating layer 131 is not in contact with the pixel electrode 111. Here, Figure 5A is a cross-sectional view corresponding to the dashed lines A1-A2 and C1-C2 in Figure 1A, and Figure 5B is a cross-sectional view corresponding to the dashed lines B1-B2. In addition, Figure 5C shows an enlarged view of the area surrounded by the rectangle with dashed lines in Figure 5A.

[0099] Since the EL layer 112 covers the top and side surfaces of the pixel electrode 111, the formation processes of the EL layer 112 and the insulating layer 131 can be performed without exposing the pixel electrode 111. Therefore, damage to the pixel electrode 111 can be reduced during the formation processes of the EL layer 112 and the insulating layer 131, thus improving the yield of the light-emitting element 110 and enhancing its display quality.

[0100] Alternatively, as shown in Figures 6A and 6B, a structure in which the lower end of the side surface of the EL layer 112 is approximately aligned with the lower end of the side surface of the pixel electrode 111 can be adopted. By adopting this structure, the formation processes of the EL layer 112 and the insulating layer 131 can be performed with a small distance between the light-emitting elements 110 and without exposing the pixel electrode 111. Here, Figure 6A is a cross-sectional view corresponding to the dashed lines A1-A2 and C1-C2 in Figure 1A, and Figure 6B is a cross-sectional view corresponding to the dashed lines B1-B2.

[0101] Alternatively, as shown in Figures 6C and 6D, the EL layer 112 can also be formed only on the flat portion of the pixel electrode 111 without crossing the end of the pixel electrode 111. Note that, unlike Figures 1B and 1C, the lower end of the side surface of the EL layer 112 is located inside the upper end of the side surface of the pixel electrode 111. Therefore, the EL layer 112 can be formed in a manner that allows for some clearance relative to the pixel electrode 111.

[0102] An insulating layer 131 is provided between adjacent light-emitting elements 110. The insulating layer 131 is located between each EL layer 112 included in the light-emitting element 110. In addition, a common electrode 113 is provided on the insulating layer 131.

[0103] The insulating layer 131 is disposed, for example, between two EL layers 112 that are different colors. Alternatively, the insulating layer 131 is disposed, for example, between two EL layers 112 that are the same color. Alternatively, the insulating layer 131 may be disposed between two EL layers 112 that are different colors instead of between two EL layers 112 that are the same color.

[0104] For example, as shown in Figures 1A to 1C, the insulating layer 131 is disposed between the EL layers 112 between adjacent pixels so as to have a mesh (or grid or matrix) shape when viewed from above.

[0105] EL layers 112R, EL layers 112G, and EL layers 112B preferably have a region that contacts the top surface of the pixel electrode and a region that contacts the side surface of the insulating layer 131. The ends of EL layers 112R, EL layers 112G, and EL layers 112B preferably contact the side surface of the insulating layer 131. Furthermore, as shown in Figures 1B and 1C, it is preferable that the ends of pixel electrodes 111R, 111G, and 111B also contact the side surface of the insulating layer 131.

[0106] By providing an insulating layer 131 between light-emitting elements of different colors, contact between EL layers 112R, EL layers 112G, and EL layers 112B can be prevented. This effectively prevents unintended light emission caused by current flowing through adjacent EL layers. Consequently, contrast can be improved, enabling a display device with high display quality.

[0107] Alternatively, the insulating layer 131 may not be provided between adjacent pixels displaying the same color, but only between pixels displaying different colors. In this case, the insulating layer 131 can be configured in a striped shape when viewed from above. By configuring the insulating layer 131 in a striped shape, compared to configuring it in a grid shape, no space is needed to form the insulating layer 131, so the aperture ratio can be increased. When the insulating layer 131 is configured in a striped shape, adjacent EL layers of the same color can also be processed into strips to be continuous in the column direction.

[0108] Between adjacent light-emitting elements, a step is formed near the end of the EL layer 112, resulting from the region where the EL layer 112 is disposed, the region where the pixel electrode 111 is disposed, and the region where neither the EL layer 112 nor the pixel electrode 111 is disposed. In one embodiment of the display device of the present invention, this step is planarized by including an insulating layer 131. Compared to the case where the shared electrode 113 is in contact with the substrate 101 between adjacent light-emitting elements, the coverage of the shared electrode 113 can be improved, thus suppressing poor connection due to disconnection. Alternatively, the increase in resistance due to localized thinning of the shared electrode 113 caused by the step can be suppressed.

[0109] In one embodiment of the present invention, by providing an insulating layer 131 between adjacent EL layers 112, the unevenness of the formation surface of the common electrode 113 can be reduced, thereby improving the coverage of the common electrode 113 near the end of the EL layer 112, thereby achieving good conductivity of the common electrode 113.

[0110] As described above, by making the pixel electrode 111 tapered, the insulating layer 131 can be provided without the corrugated structure being formed between the pixel electrodes 111. This further reduces the unevenness of the formation surface of the common electrode 113. Therefore, good conductivity of the common electrode 113 can be achieved, and the display quality of the display device can be improved.

[0111] The insulating layer 131 preferably includes an insulating layer 131a and an insulating layer 131b disposed beneath the insulating layer 131a. The insulating layer 131b is preferably disposed in contact with the sides of each EL layer 112 in the light-emitting element 110. Furthermore, the insulating layer 131b is preferably disposed in contact with the sides of each pixel electrode 111 in the light-emitting element 110. For example, as shown in Figures 1B and 1C, the insulating layer 131b is preferably disposed in a manner that covers the sides of each EL layer 112 and the sides of the pixel electrode 111 in the light-emitting element 110.

[0112] In addition, the insulating layer 131b is provided in contact with the side and bottom surfaces of the insulating layer 131a. In other words, when viewed in cross-section, the insulating layer 131a is provided in contact with the top surface of the insulating layer 131b in a way that fills the recess of the insulating layer 131b.

[0113] By adopting the above structure, as shown in Figures 1B and 1C, the insulating layer 131a is arranged to overlap with the side of the EL layer 112 (or, to say, to be opposite to the side of the EL layer 112) through the insulating layer 131b. That is, the insulating layer 131a and the EL layer 112 are separated by the insulating layer 131b.

[0114] The insulating layer 131b has an area in contact with the side of the EL layer 112 and serves as a protective insulating layer for the EL layer 112. Preferably, the insulating layer 131b is resistant to at least one of oxygen and moisture. By separating the insulating layer 131a from the EL layer 112 through such an insulating layer 131b, the ingress of oxygen, moisture, or their constituent elements from the side of the EL layer 112 can be suppressed, thereby enabling a highly reliable display device.

[0115] When viewed in cross-section, if the width of the insulating layer 131b in the area contacting the side of the EL layer 112 is large, the spacing of the EL layers 112 may increase, resulting in a decrease in the aperture ratio. Conversely, if the width of the insulating layer 131b is small, the effect of suppressing oxygen, moisture, or their constituent elements from entering the interior from the side of the EL layer 112 may decrease. Preferably, the width of the insulating layer 131b in the area contacting the side of the EL layer 112 is 3 nm or more and 200 nm or less, more preferably 3 nm or more and 150 nm or less, further preferably 5 nm or more and 150 nm or less, even more preferably 5 nm or more and 100 nm or less, still more preferably 10 nm or more and 100 nm or less, and most preferably 10 nm or more and 50 nm or less. By setting the width of the insulating layer 131b within the above range, a display device with high aperture ratio and high reliability can be achieved.

[0116] The insulating layer 131b can be an insulating layer containing inorganic materials. For example, a single layer or stack of materials such as aluminum oxide, magnesium oxide, hafnium oxide, gallium oxide, indium gallium zinc oxide, silicon oxide, silicon oxynitride, silicon nitride, or silicon oxynitride can be used as the insulating layer 131b. In particular, aluminum oxide has a high selectivity to EL layer 112 during etching and has a protective function for EL layer 112 during the formation of the subsequent insulating layer 131b, so it is preferred. In particular, by using inorganic insulating materials such as aluminum oxide, hafnium oxide, and silicon oxide formed by atomic layer deposition (ALD) as the insulating layer 131b, a film with fewer pinholes can be achieved, and an insulating layer 131b with excellent protective function for EL layer 112 can be achieved.

[0117] Note that in this specification, "oxynitride" refers to a material in which the oxygen content is greater than the nitrogen content in its composition, while "nitrogen oxide" refers to a material in which the nitrogen content is greater than the oxygen content in its composition. For example, when described as "silicon oxynitride", it refers to a material in which the oxygen content is greater than the nitrogen content in its composition, while when described as "silicon oxynitride", it refers to a material in which the nitrogen content is greater than the oxygen content in its composition.

[0118] The insulating layer 131b can be formed by sputtering, chemical vapor deposition (CVD), molecular beam epitaxy (MBE), pulsed laser deposition (PLD), ALD, etc. In addition, the insulating layer 131b is suitable for formation using the ALD method, which has good coverage.

[0119] The insulating layer 131a disposed on the insulating layer 131b has the function of flattening the recesses of the insulating layer 131b formed between adjacent light-emitting elements. In other words, by including the insulating layer 131a, the flatness of the formation surface of the common electrode 113 is improved. As the insulating layer 131a, an insulating layer containing organic materials can be used. For example, acrylic resin, polyimide resin, epoxy resin, polyimide resin, polyimide-polyimide resin, silicone resin, benzocyclobutene resin, phenolic resin, and precursors of the above resins can be used as the insulating layer 131a. In addition, a photosensitive resin can be used as the insulating layer 131a. Positive or negative materials can be used as the photosensitive resin.

[0120] When the insulating layer 131a is formed using a photosensitive resin, the insulating layer 131a can be manufactured using only an exposure and development process. Alternatively, a negative photosensitive resin (such as a photoresist material) can also be used to form the insulating layer 131a. Furthermore, when an insulating layer containing organic materials is used as the insulating layer 131a, it is preferable to use a material that absorbs visible light. When a material that absorbs visible light is used in the insulating layer 131a, the insulating layer 131a can absorb the light emitted from the EL layer 112, and can suppress light (stray light) that may leak into adjacent EL layers 112. Therefore, a display device with high display quality can be provided.

[0121] To improve the flatness of the formation surface of the common electrode 113, the top surfaces of the end insulating layers 131a and 131b of the EL layer 112 can be approximately aligned with the top surface of the EL layer 112. Furthermore, the top surface of the insulating layer 131 preferably has a flat shape. Note that the top surfaces of the insulating layers 131a, 131b, and EL layer 112 do not need to be aligned.

[0122] For example, the height difference between the top surface of the insulating layer 131a and the top surface of the EL layer 112 is preferably less than 0.5 times the thickness of the insulating layer 131a, and more preferably less than 0.3 times the thickness of the insulating layer 131a. Alternatively, the insulating layer 131a may be provided such that the top surface of the EL layer 112 is higher than the top surface of the insulating layer 131a. Alternatively, the insulating layer 131a may be provided such that the top surface of the insulating layer 131a is higher than the top surface of the light-emitting layer included in the EL layer 112.

[0123] Furthermore, in EL layers 112 corresponding to different colors, when the top surface height of EL layers 112 is different, the top surface height of the insulating layer 131a near each EL layer 112 can be made approximately the same as the top surface height of the EL layer 112. Additionally, the top surface height of the insulating layer 131b in the area contacting the side of each EL layer 112 can be made approximately the same as the height of the EL layer 112. For example, as shown in FIG2A, the top surface height of the insulating layer 131a can be made approximately the same as the top surface height of the EL layer 112B near EL layer 112B and approximately the same as the top surface height of the EL layer 112R near EL layer 112R. For example, the top surface height of the insulating layer 131b can be made approximately the same as the top surface height of the EL layer 112B in the area contacting the side of the EL layer 112B and approximately the same as the top surface height of the EL layer 112R in the area contacting the side of the EL layer 112R.

[0124] In addition, the top surface of the insulating layer 131a may also have a shape that is concave in the center and around it (sometimes referred to as a concave curved surface shape). In addition, not limited to this, the top surface of the insulating layer 131a may also have a shape that is convex in the center and around it (sometimes referred to as a convex curved surface shape).

[0125] Note that the present invention is not limited to these structures. As shown in FIG4A, a portion of the insulating layer 131 (insulating layer 131a and insulating layer 131b) may also overlap with the adjacent EL layer 112 (EL layer 112B and EL layer 112R in FIG4A).

[0126] Additionally, when a portion of the insulating layer 131 overlaps with the adjacent EL layer 112, a portion of the sacrificial layer 145 may sometimes be formed between the portion of the insulating layer 131 and the EL layer 112. The sacrificial layer 145 refers to a layer containing inorganic material that is used as a hard mask when the EL layer 112 is formed. Preferably, the sacrificial layer 145 is a stacked structure having a sacrificial layer 145a with a high etch selectivity to the EL layer and a sacrificial layer 145b on the sacrificial layer 145a. The details of the sacrificial layer 145 will be explained in the following section on the manufacturing method of the display device.

[0127] For example, as shown in FIG4A, insulating layer 131 (insulating layer 131a and insulating layer 131b) includes: a first region located on EL layer 112B and overlapping with the top surface of EL layer 112B; and a second region located on EL layer 112R and overlapping with the top surface of EL layer 112R. Sacrificial layers 145a and 145b are formed between the first region of insulating layer 131 and EL layer 112B, and between the second region of insulating layer 131b and EL layer 112R.

[0128] Here, as shown in FIG4A, the first and second regions of the insulating layer 131 are preferably connected in a manner that has a smooth curved surface from the top surface to the side surface. By adopting such a shape, the common layer 114 and the common electrode 113 can be deposited on the insulating layer 131 with high coverage, and the occurrence of disconnection can be suppressed.

[0129] In addition, as shown in FIG5D, in the same way in the display device 100 shown in FIG5A to FIG5C, a portion of the insulating layer 131 (insulating layer 131a and insulating layer 131b) may also overlap with the adjacent EL layer 112 (EL layer 112B and EL layer 112R in FIG5D).

[0130] Additionally, as shown in FIG1B, the insulating layer 131 is sometimes formed on the side of the connecting electrode 111C. In this case, a sacrificial layer 145R is sometimes formed between the connecting electrode 111C and the insulating layer 131.

[0131] Additionally, as shown in FIG4B, the insulating layer 131b can also be a laminated film of insulating layer 131b1 and insulating layer 131b2 on insulating layer 131b1. As insulating layer 131b1 and insulating layer 131b2, the aforementioned inorganic materials suitable for insulating layer 131b can be appropriately used. For example, alumina deposited by ALD method can be used as insulating layer 131b1, and silicon nitride deposited by sputtering method can be used as insulating layer 131b2. By adopting such a structure, the insulating layer 131b1 is formed into a film with few pinholes with high coverage, and silicon nitride is provided as insulating layer 131b2, which can improve the barrier properties against oxygen and moisture.

[0132] In addition, a protective layer 121 is provided on the common electrode 113 to cover the light-emitting elements 110R, 110G and 110B. The protective layer 121 has the function of preventing impurities such as water from diffusing from above to each light-emitting element.

[0133] The protective layer 121 may, for example, have a single-layer structure or a multilayer structure comprising at least an inorganic insulating film. As the inorganic insulating film, for example, oxide films or nitride films such as silicon oxide films, silicon oxynitride films, silicon oxynitride films, silicon nitride films, aluminum oxide films, aluminum oxynitride films, hafnium oxide films, etc., may be used. Alternatively, semiconductor materials such as indium gallium oxide and indium gallium zinc oxide may also be used as the protective layer 121.

[0134] Alternatively, a laminated film of an inorganic insulating film and an organic insulating film can be used as the protective layer 121. For example, it is preferable to sandwich an organic insulating film between a pair of inorganic insulating films. Furthermore, the organic insulating film is preferably used as a planarization film. As a result, the top surface of the organic insulating film can be flattened, thus improving the coverage of the inorganic insulating film on the organic insulating film and thereby improving the barrier properties. In addition, since the top surface of the protective layer 121 is flattened, the influence of the uneven shape of the underlying structure can be reduced when a structure (e.g., a color filter, electrodes of a touch sensor, or a lens array, etc.) is provided above the protective layer 121, which is preferable.

[0135] Similar to the common electrode 113, the common layer 114 is disposed across multiple light-emitting elements. The common layer 114 covers the EL layers 112R, EL layers 112G, and EL layers 112B. By including the common layer 114, the manufacturing process can be simplified, thus reducing manufacturing costs. The common layer 114 and the common electrode 113 can be formed continuously without etching or other processes during their fabrication. Therefore, the interface between the common layer 114 and the common electrode 113 can be clean, resulting in good characteristics in the light-emitting elements.

[0136] EL layers 112R, EL layers 112G, and EL layers 112B are preferably light-emitting layers comprising a light-emitting material that emits at least one color of light. Additionally, the common layer 114 is preferably a layer comprising one or more of an electron injection layer, an electron transport layer, a hole injection layer, and a hole transport layer. In a light-emitting element where a pixel electrode is used as the anode and a common electrode is used as the cathode, the common layer 114 may employ a structure including an electron injection layer or a structure comprising both an electron injection layer and an electron transport layer.

[0137] [Pixel Layout] Next, the pixel layout different from that in Figure 1A will be explained. There are no particular restrictions on the arrangement of subpixels, and various methods can be used. Examples of subpixel arrangements include stripe arrangements, S-stripe arrangements, matrix arrangements, Delta arrangements, Bayer arrangements, Pentile arrangements, etc.

[0138] Furthermore, examples of the top surface shape of a sub-pixel include triangles, quadrilaterals (rectangles, squares), pentagons, and other polygons, as well as the aforementioned polygonal shapes with rounded corners, ellipses, or circles. Here, the top surface shape of the sub-pixel corresponds to the top surface shape of the light-emitting area of ​​the light-emitting element.

[0139] Pixel 103 shown in Figure 7A is arranged in an S-Stripe pattern. Pixel 103 shown in Figure 7A is composed of three sub-pixels: sub-pixel 103a, sub-pixel 103b, and sub-pixel 103c. For example, as shown in Figure 8A, sub-pixel 103a can also be a blue sub-pixel B, sub-pixel 103b can also be a red sub-pixel R, and sub-pixel 103c can also be a green sub-pixel G.

[0140] The pixel 103 shown in FIG7B includes a sub-pixel 103a with a top surface shape of approximately trapezoidal shape with rounded corners, a sub-pixel 103b with a top surface shape of approximately triangle with rounded corners, and a sub-pixel 103c with a top surface shape of approximately quadrilateral or approximately hexagonal shape with rounded corners. Furthermore, the light-emitting area of ​​sub-pixel 103a is larger than that of sub-pixel 103b. Thus, the shape and size of each sub-pixel can be determined independently. For example, the size of a sub-pixel including a highly reliable light-emitting element can be smaller. For example, as shown in FIG8B, sub-pixel 103a can also be a green sub-pixel G, sub-pixel 103b can also be a red sub-pixel R, and sub-pixel 103c can also be a blue sub-pixel B.

[0141] Pixels 124a and 124b shown in FIG. 7C are arranged in a Pentile pattern. FIG. 7C shows an example of pixels 124a, which includes sub-pixels 103a and 103b, and pixels 124b, which includes sub-pixels 103b and 103c, arranged alternately. For example, as shown in FIG. 8C, sub-pixel 103a can also be a red sub-pixel R, sub-pixel 103b can also be a green sub-pixel G, and sub-pixel 103c can also be a blue sub-pixel B.

[0142] Pixels 124a and 124b shown in Figures 7D and 7E are arranged in a Delta pattern. Pixel 124a includes two sub-pixels (sub-pixel 103a and sub-pixel 103b) in the previous row (first row) and one sub-pixel (sub-pixel 103c) in the next row (second row). Pixel 124b includes one sub-pixel (sub-pixel 103c) in the previous row (first row) and two sub-pixels (sub-pixel 103a and sub-pixel 103b) in the next row (second row). For example, as shown in Figure 8D, sub-pixel 103a can also be a red sub-pixel R, sub-pixel 103b can also be a green sub-pixel G, and sub-pixel 103c can also be a blue sub-pixel B.

[0143] Figure 7D is an example of a top surface shape with rounded corners for each sub-pixel, and Figure 7E is an example of a top surface shape with rounded corners for each sub-pixel.

[0144] Figure 7F shows an example of subpixels of various colors arranged in a zigzag pattern. Specifically, when viewed from above, the upper edges of two subpixels arranged in the column direction (e.g., subpixels 103a and 103b, or subpixels 103b and 103c) are not in the same position. For example, as shown in Figure 8E, subpixel 103a could also be a red subpixel R, subpixel 103b could also be a green subpixel G, and subpixel 103c could also be a blue subpixel B.

[0145] In photolithography, the finer the pattern being processed, the more significant the effect of light diffraction becomes. Therefore, when transferring the pattern from the photomask through exposure, its fidelity decreases, making it difficult to process the photomask into the desired shape. Consequently, even if the photomask pattern is rectangular, it is easy to form a pattern with rounded corners. Therefore, the top surface shape of a subpixel sometimes takes the form of a polygon with rounded corners, an ellipse, or a circle.

[0146] Furthermore, in a method for manufacturing a display device according to one embodiment of the present invention, the EL layer is processed into an island shape using a photoresist mask. The photoresist film formed on the EL layer needs to be cured at a temperature lower than the heat resistance temperature of the EL layer. Therefore, depending on the heat resistance temperature of the EL layer material and the curing temperature of the photoresist material, the photoresist film is sometimes not sufficiently cured. The insufficiently cured photoresist film sometimes takes on a shape far from the desired shape during processing. As a result, the top surface shape of the EL layer is sometimes a polygonal shape with rounded corners, an ellipse, or a circle, etc. For example, when a photoresist mask with a square top surface shape is to be formed, sometimes a photoresist mask with a circular top surface shape is formed and the top surface shape of the EL layer is circular.

[0147] In order to make the top surface shape of the EL layer the desired shape, a technique for correcting the mask pattern in advance by making the design pattern consistent with the transfer pattern (OPC (Optical Proximity Correction) technique) can also be used. Specifically, in the OPC technique, correction patterns are added to the corners of the pattern on the mask pattern.

[0148] [Example of Manufacturing Method] Hereinafter, an example of a method for manufacturing a display device according to an embodiment of the present invention will be described with reference to drawings. Here, the display device 100 shown in FIG1 according to the above-described structural example will be used as an example for description. FIGS. 9A to 11E are schematic cross-sectional views of each process in the manufacturing method of the display device illustrated below.

[0149] Thin films (insulating films, semiconductor films, conductive films, etc.) constituting display devices can be formed using sputtering, CVD, vacuum evaporation, PLD, ALD, and other methods. CVD methods include plasma-enhanced chemical vapor deposition (PECVD) and thermal CVD. Furthermore, one type of thermal CVD method is metal-organic chemical vapor deposition (MOCVD).

[0150] In addition, the thin films (insulating films, semiconductor films, conductive films, etc.) constituting the display device can be formed by methods such as spin coating, dip coating, spray coating, inkjet coating, distributor coating, screen printing, flatbed printing, doctor knife coating, slot coating, roller coating, curtain coating, and doctor knife coating.

[0151] Furthermore, when processing the thin film constituting the display device, it can be processed using methods such as photolithography. In addition to the methods mentioned above, the thin film can also be processed using nanoimprinting, sandblasting, and peeling methods. Furthermore, island-shaped thin films can be directly formed using shadow mask deposition methods such as metal masks.

[0152] Photolithography typically includes two methods. One method involves forming a photoresist mask on the film to be processed, processing the film by etching, and then removing the photoresist mask. The other method involves depositing a photosensitive film, followed by exposure and development to process the film into the desired shape.

[0153] In photolithography, the light used for exposure can be, for example, i-line (wavelength 365nm), g-line (wavelength 436nm), h-line (wavelength 405nm), or a mixture of these. Additionally, ultraviolet light, KrF laser, or ArF laser can also be used. Furthermore, immersion exposure technology can be used. Additionally, extreme ultraviolet (EUV) light or X-rays can be used as the light for exposure. Alternatively, an electron beam can be used instead of the light used for exposure. When using extreme ultraviolet light, X-rays, or an electron beam, extremely fine processing can be performed, making it preferable. Note that when exposure is performed by scanning with a beam such as an electron beam, a photomask may not be used.

[0154] As a method for etching thin films, dry etching, wet etching and sandblasting can be used.

[0155] [Preparation of Substrate 101] As substrate 101, a substrate with heat resistance sufficient to withstand subsequent heat treatment can be used. When using an insulating substrate as substrate 101, glass substrate, quartz substrate, sapphire substrate, ceramic substrate, organic resin substrate, etc., can be used. In addition, single-crystal semiconductor substrates or polycrystalline semiconductor substrates made of materials such as silicon or silicon carbide, compound semiconductor substrates made of materials such as silicon and germanium, SOI substrates, etc., can also be used.

[0156] In particular, the substrate 101 is preferably a substrate on which a semiconductor circuit including semiconductor elements such as transistors is formed on the aforementioned semiconductor substrate or insulating substrate. This semiconductor circuit is preferably, for example, a pixel circuit, a gate line drive circuit (gate driver), a source line drive circuit (gate driver), etc. In addition, it can also be configured as an arithmetic circuit, a memory circuit, etc.

[0157] [Forming of Pixel Electrode 111] Next, a conductive film forming the pixel electrode 111 and the connection electrode 111C is deposited on the substrate 101. Then, a portion of the conductive film is etched to form the pixel electrode 111R, pixel electrode 111G, pixel electrode 111B, and connection electrode 111C on the substrate 101 (FIG. 10A). The deposition of the conductive film forming the pixel electrode 111 and the connection electrode 111C can be performed using any one or more of sputtering, CVD, PLD, and ALD methods. Furthermore, the etching of the pixel electrode 111 and the connection electrode 111C can be performed using any one or more of dry etching and wet etching methods.

[0158] The distance between adjacent pixel electrodes 111 can be reduced to less than 3 μm, less than 2 μm, or less than 1 μm. For example, by using an LSI exposure apparatus, this distance can be reduced to less than 500 nm, less than 200 nm, less than 100 nm, or even less than 50 nm. As a result, the area of ​​the non-light-emitting region that may exist between the two light-emitting elements 110 can be significantly reduced, and the aperture ratio can be improved.

[0159] Here, an example of a method for manufacturing the pixel electrode 111 with the four-layer structure shown in FIG2B will be described using FIG9A to FIG9F.

[0160] First, conductive films 111aA, 111bA, 111cA, and 111dA are sequentially deposited on an insulating layer 101a on a substrate 101 on which a semiconductor circuit is formed. Here, conductive film 111aA becomes conductive layer 111a in a subsequent process, conductive film 111bA becomes conductive layer 111b in a subsequent process, conductive film 111cA becomes conductive layer 111c in a subsequent process, and conductive film 111dA becomes conductive layer 111d in a subsequent process.

[0161] Conductive films 111aA, 111bA, 111cA, and 111dA can be deposited using the conductive material described above, which is suitable for conductive layers 111a, 111b, 111c, and 111d. For example, titanium deposited by sputtering can be used as conductive films 111aA and 111cA. Additionally, aluminum deposited by sputtering can be used as conductive film 111bA. Furthermore, indium tin oxide containing silicon can be deposited by sputtering as conductive film 111dA.

[0162] Furthermore, it is preferable to deposit the conductive films 111aA, 111bA, and 111cA continuously without exposure to the atmosphere. This allows deposition of the conductive film 111bA without oxidation. Additionally, it is preferable to oxidize the conductive film 111cA by performing heat treatment after deposition. This allows the conductive film 111cA to contain highly transparent titanium oxide.

[0163] Next, a photoresist mask 115a (FIG. 9A) is formed on the conductive film 111dA. The photoresist mask 115a can be a photoresist material containing a photosensitive resin, such as a positive photoresist material or a negative photoresist material.

[0164] Next, heat treatment is performed in an oxygen-containing atmosphere to process the photoresist mask 115a to form the photoresist mask 115b (Fig. 9B). As shown in Fig. 9B, the side surface of the photoresist mask 115b is preferably conical. Furthermore, as shown in Fig. 9B, a curved surface is formed on the upper part of the side surface of the photoresist mask 115b, giving the photoresist mask 115b a shape where the side surface and top surface are smoothly connected. The heat treatment described above can be performed within a temperature range where the organic material components of the photoresist mask 115a will not be completely decomposed, for example, at approximately 140°C to 180°C.

[0165] Next, an etching process is performed to process the conductive film 111dA to form the conductive layer 111d (FIG. 9C). When indium tin oxide containing silicon is used as the conductive film 111dA, the etching process is preferably performed using a wet etching method. For example, an organic acid containing citric acid or oxalic acid can be used. In this case, as shown in FIG. 9C, sometimes the side having the conductive layer 111d is recessed relative to the side of the photoresist mask 115b.

[0166] Next, an etching process is performed to process the conductive films 111cA and 111bA to form conductive layers 111c and 111b (FIG. 9D). Preferably, this etching process is stopped before the conductive film 111aA is etched. Note that a portion of the conductive film 111aA may sometimes be removed due to this etching.

[0167] Here, as shown in FIG9D, the photoresist mask 115b is also etched to form a reduced photoresist mask 115c. While the photoresist mask 115b with a conical shape is reduced to the photoresist mask 115c, the conductive layers 111c and 111b are etched, thereby making the sides of the conductive layers 111c and 111b conical in shape. Here, by setting the etching rate of the conductive layers 111c and 111b to a higher etching rate than that of the photoresist mask 115b, the time required to form the conductive layers 111c and 111b can be shortened, thereby improving the productivity of the display device.

[0168] When titanium is used as the conductive film 111cA and aluminum is used as the conductive film 111bA, the etching process is preferably performed using a dry etching method. In this case, a chlorine-based gas is preferably used as the etching gas. As the chlorine-based gas, gases such as Cl2, BCl3, SiCl4, and CCl4 can be used alone or in mixtures of two or more. In addition, oxygen gas, hydrogen gas, helium gas, and argon gas can be appropriately added to the aforementioned chlorine-based gas, either alone or in mixtures of two or more gases.

[0169] As a dry etching apparatus, a dry etching apparatus having a high-density plasma source can be used. For example, an inductively coupled plasma (ICP) etching apparatus can be used. Alternatively, a capacitively coupled plasma (CCP) etching apparatus including parallel planar electrodes can be used. The capacitively coupled plasma etching apparatus including parallel planar electrodes can also employ a structure in which a high-frequency voltage is applied to one of the parallel planar electrodes. Alternatively, a structure in which multiple different high-frequency voltages are applied to one of the parallel planar electrodes can be used. Alternatively, a structure in which high-frequency voltages of the same frequency are applied to each of the parallel planar electrodes can be used. Alternatively, a structure in which high-frequency voltages of different frequencies are applied to each of the parallel planar electrodes can be used.

[0170] Next, an etching process is performed to process the conductive film 111aA to form the conductive layer 111a (FIG. 9E). Since the sides of the conductive layers 111a to 111c are etched during this etching process, the side of the pixel electrode 111 is formed into a tapered shape. Additionally, sometimes the side of the conductive layer 111d is also etched to form a tapered shape. Furthermore, sometimes the area of ​​the insulating layer 101a that does not overlap with the pixel electrode 111 is etched, and a recess is formed in this area.

[0171] As shown in FIG9E, in this etching process, the photoresist mask 115c is also etched to form a further reduced photoresist mask 115d. At this time, by setting the etching rate of the photoresist mask 115d to a higher etching rate than that of the pixel electrode 111, the side of the pixel electrode 111 can be made to have a tapered shape. For example, it is preferable to set the etching rate of the photoresist mask 115d to a higher etching rate than that of the conductive layer 111c.

[0172] When titanium is used as the conductive film 111aA, the etching process is preferably performed using a dry etching method. In this case, the etching gas is preferably a mixture of chlorine gas and fluorine gas to reduce the vapor pressure of the reaction products. Note that the flow rate of the chlorine etching gas is preferably set to a lower flow rate than that of the etching process according to FIG. 9D. This reduces the etching rate of the conductive layer 111c and relatively increases the etching rate of the photoresist mask 115d, making it easier to form the pixel electrode 111 into a conical shape. Here, fluorine gases such as CF4, SF6, NF3, CHF3, C4F6, C5F6, C4F8, and C5F8 can be used alone or in mixtures of two or more. Alternatively, one or more gases such as oxygen, hydrogen, helium, and argon can be appropriately added to the aforementioned chlorine and fluorine gases, either alone or in mixtures of two or more gases.

[0173] Furthermore, it is preferable to set the bias power in the etching process according to FIG. 9E to a higher bias power than that in the etching process according to FIG. 9D. This can further increase the etching rate of the photoresist mask 115d.

[0174] Next, the photoresist mask 115d is removed (Fig. 9F). The removal of the photoresist mask 115d can be performed using wet etching or dry etching. For example, the photoresist mask 115d can be removed using dry etching (also known as plasma ashing) that uses oxygen gas as the etching gas.

[0175] Thus, a pixel electrode 111 with a cone shape having a cone angle θ can be formed. Here, the cone angle θ is less than 90°, preferably less than 80°, more preferably less than 70°, and even more preferably less than 50°.

[0176] Note that the pixel electrode 111 shown in FIG9F has the sides of conductive layers 111a to 111d forming a shape that is substantially the same plane, but the present invention is not limited thereto. As shown in FIG3A to FIG3C, sometimes one or more of the sides of conductive layers 111a to 111d have a recessed shape.

[0177] [Formation of EL film 112Rf] Next, an EL film 112Rf, which will later become EL layer 112R, is deposited on pixel electrode 111R, pixel electrode 111G, and pixel electrode 111B.

[0178] The EL film 112Rf includes at least a film containing a luminescent compound. In addition, one or more films used as an electron injection layer, electron transport layer, charge generation layer, hole transport layer, or hole injection layer may be laminated. The EL film 112Rf can be formed, for example, by evaporation (including vacuum evaporation), sputtering, or inkjet printing. Furthermore, it is not limited to these methods; the above-described deposition methods can be used appropriately.

[0179] [Formation of sacrificial film 144R] Next, the deposition process of the sacrificial film will be described.

[0180] Sacrificial film 144R is the film that becomes sacrificial layer 145R. Furthermore, sacrificial film 144G, described later, is the film that becomes sacrificial layer 145G, and sacrificial film 144B is the film that becomes sacrificial layer 145B. Sometimes, sacrificial layers 145R, 145G, and 145B are collectively referred to as sacrificial layer 145. Sacrificial layer 145 can be a single-layer structure or a multi-layer structure with two or more layers.

[0181] The following shows an example of a sacrificial layer using a two-layer structure.

[0182] In the following examples, sacrificial films 144R, 144G, and 144B are preferably a laminated structure having sacrificial films 144a and 144b. Here, sacrificial film 144a is a film that becomes sacrificial layer 145a, and sacrificial film 144b is a film that becomes sacrificial layer 145b. At this time, sacrificial layers 145R, 145G, and 145B have a laminated structure having sacrificial layers 145a and 145b. At this time, as shown in Figures 4A and 4B, a portion of sacrificial layer 145a and a portion of sacrificial layer 145b sometimes remain on the end of EL layer 112.

[0183] As a deposition process for the sacrificial film 144R, the sacrificial film 144a is formed by covering the EL film 112Rf, and the sacrificial film 144b is formed thereon. In addition, the sacrificial film 144R is provided in contact with the top surface of the connecting electrode 111C.

[0184] In the formation of sacrificial films 144a and 144b, for example, sputtering, ALD (thermal ALD, PEALD), or vacuum evaporation can be used. Note that the sacrificial film 144a, which is formed directly on the EL film 112Rf, is preferably formed using a method that causes less damage to the EL layer. Therefore, compared with sputtering, it is preferable to form the sacrificial film 144a using ALD or vacuum evaporation.

[0185] As the sacrificial membrane 144a, inorganic membranes such as metal membranes, alloy membranes, metal oxide membranes, semiconductor membranes, and inorganic insulating membranes can be appropriately used.

[0186] Additionally, an oxide film can be used as the sacrificial film 144a. Typically, oxide films or oxynitride films such as silicon oxide, silicon oxynitride, aluminum oxide, aluminum oxynitride, hafnium oxide, and hafnium oxynitride can also be used. Furthermore, nitride films can be used as the sacrificial film 144a, for example. Specifically, nitrides such as silicon nitride, aluminum nitride, hafnium nitride, titanium nitride, tantalum nitride, tungsten nitride, gallium nitride, and germanium nitride can also be used. These inorganic insulating materials can be formed using deposition methods such as sputtering, CVD, or ALD. The ALD method is particularly preferred for the sacrificial film 144a formed directly on the EL film 112Rf.

[0187] As the sacrificial film 144a, for example, metallic materials such as gold, silver, platinum, magnesium, nickel, tungsten, chromium, molybdenum, iron, cobalt, copper, palladium, titanium, aluminum, yttrium, zirconium, and tantalum, or alloy materials containing such metallic materials, can be used. In particular, low-melting-point materials such as aluminum or silver are preferred.

[0188] Alternatively, indium gallium zinc oxide (In-Ga-Zn oxide, also referred to as IGZO) or other metal oxides can be used as the sacrificial film 144a. Other sacrificial films 144a may include indium oxide, indium zinc oxide (In-Zn oxide), indium tin oxide (In-Sn oxide, also referred to as ITO), indium titanium oxide (In-Ti oxide), indium tin zinc oxide (In-Sn-Zn oxide), indium titanium zinc oxide (In-Ti-Zn oxide), indium gallium tin zinc oxide (In-Ga-Sn-Zn oxide), etc. Alternatively, silicon-containing indium tin oxide or similar materials may be used.

[0189] Note that this can also be applied to cases where element M (M is one or more of aluminum, silicon, boron, yttrium, copper, vanadium, beryllium, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, and magnesium) is used to replace gallium.

[0190] The sacrificial membrane 144b can be any of the materials listed above that can be used as sacrificial membrane 144a. Alternatively, one of the materials listed above that can be used as sacrificial membrane 144a can be selected as sacrificial membrane 144a, and another can be selected as sacrificial membrane 144b. Alternatively, one or more materials listed above that can be used as sacrificial membrane 144a can be selected as sacrificial membrane 144a, and a material selected from materials other than those selected as sacrificial membrane 144a can be used as sacrificial membrane 144b.

[0191] The sacrificial film 144a can be a film with high resistance to etching of various EL films such as EL film 112Rf, that is, a film with a larger etching selectivity. Furthermore, the sacrificial film 144a is particularly preferably a film that can be removed by wet etching with less damage to each EL film.

[0192] Furthermore, as the sacrificial membrane 144a, a material that is chemically stable in a solvent that is soluble in the uppermost layer of the EL membrane 112Rf can also be used. In particular, a material soluble in water or alcohol can be suitable for use as the sacrificial membrane 144a. When depositing the sacrificial membrane 144a, it is preferable to coat it using a wet deposition method in a solvent such as water or alcohol, and then perform a heat treatment to evaporate the solvent. At this time, by performing the heat treatment under a reduced pressure atmosphere, the solvent can be removed at a low temperature and in a short time, so the thermal damage to the EL membrane 112Rf can be reduced, which is preferable.

[0193] As a wet deposition method that can be used to form the sacrificial film 144a, examples include spin coating, dip coating, spray coating, inkjet coating, dispenser coating, screen printing, flatbed printing, doctor blade coating, slot coating, roller coating, curtain coating, and doctor blade coating.

[0194] As the sacrificial membrane 144a, organic materials such as polyvinyl alcohol (PVA), polyvinyl butyral, polyvinylpyrrolidone, polyethylene glycol, polyglycerol, pullulan, water-soluble cellulose, or polyamide resin soluble in alcohol can be used.

[0195] As the sacrificial membrane 144b, a membrane with a larger selection ratio than the sacrificial membrane 144a can be used.

[0196] Particularly preferred is that the sacrificial film 144a uses inorganic insulating materials such as alumina, hafnium oxide, and silicon oxide formed by the ALD method, and the sacrificial film 144b uses indium-containing metal oxides such as IGZO formed by sputtering. Alternatively, tungsten formed by sputtering can also be used as the sacrificial film 144b.

[0197] Alternatively, an organic film suitable for the EL film 112Rf, etc., can be used as the sacrificial film 144b. For example, the same organic film used for the EL film 112Rf, EL film 112Gf, or EL film 112Bf can be used as the sacrificial film 144b. By using such an organic film, the deposition apparatus can be used interchangeably with the EL film 112Rf, etc., which is preferable. Furthermore, the sacrificial layer 145b can be removed while etching the EL film 112Rf, etc., thus simplifying the process.

[0198] For example, when dry etching using a fluorine-containing gas (also known as a fluorine-based gas) is used in the etching of the EL film 112Rf, silicon, silicon nitride, silicon oxide, tungsten, titanium, molybdenum, tantalum, tantalum nitride, alloys containing molybdenum and niobium, or alloys containing molybdenum and tungsten can be used as sacrificial film 144b. Here, as a film with a large etching selectivity (i.e., a slower etching rate) compared to dry etching using the aforementioned fluorine-based gas, metal oxide films such as IGZO and ITO can be cited, and such metal oxide films can be used as sacrificial film 144a.

[0199] [Formation of photoresist mask 143a] Next, a photoresist mask 143a is formed on the sacrificial film 144R (Fig. 10B). Fig. 10B shows an example where the EL film 112Rf is not deposited in region 130. When region 130 is shaded during the deposition of the EL film 112Rf, a metal mask can be used. Since it is not necessary to shade the pixel area of ​​the display unit with the metal mask used at this time, a high-resolution mask is not required.

[0200] The photoresist mask 143a can use photoresist materials including photosensitive resins, such as positive photoresist materials or negative photoresist materials.

[0201] Here, when a photoresist mask 143a is formed on the sacrificial film 144R, if defects such as pinholes exist in the sacrificial film 144R, the solvent of the photoresist material may dissolve the EL film 112Rf. By using inorganic insulating materials such as alumina, hafnium oxide, and silicon oxide formed by the ALD method as the sacrificial film 144a, a film with fewer pinholes can be achieved, thus preventing such defects.

[0202] [Etching of Sacrificial Film 144R] Next, a portion of the sacrificial film 144R (sacrificial film 144a and sacrificial film 144b) not covered by the photoresist mask 143a is removed by etching to form an island-shaped or strip-shaped sacrificial layer 145R (sacrificial layer 145a and sacrificial layer 145b) (FIG. 10C). Here, the sacrificial layer 145R is formed on the pixel electrode 111R. Furthermore, the sacrificial layer 145R is formed to cover the connection electrode 111C. Note that in FIG. 10C, the portion of the sacrificial layer 145R that completely covers the connection electrode 111C and contacts the upper part of the substrate 101 is relatively large; however, it is not limited to this, and the portion of the sacrificial layer 145R that contacts the upper part of the substrate 101 can be smaller. By adopting such a structure, as shown in FIG. 1B, etc., in region 130, the sacrificial layer 145R can be formed only on the side portion of the connection electrode 111C.

[0203] Preferably, a sacrificial layer 145b is formed by using a photoresist mask 143a and etching to remove a portion of the sacrificial film 144b, then the photoresist mask 143a is removed, and the sacrificial layer 145b is used as a hard mask for etching the sacrificial film 144a. In etching the sacrificial film 144b, etching conditions with a high selectivity to the sacrificial film 144a are preferably used. Wet etching or dry etching can be used in the etching process when forming the hard mask; by using dry etching, pattern shrinkage can be suppressed. For example, when an inorganic insulating material such as alumina, hafnium oxide, or silicon oxide formed by ALD is used as the sacrificial film 144a, and a metallic material such as tungsten formed by sputtering is used as the sacrificial film 144b, the sacrificial film 144b is etched, and the sacrificial film 144b is used as a hard mask.

[0204] When removing the photoresist mask 143a, wet etching or dry etching can be used. In particular, it is preferred to remove the photoresist mask 143a by dry etching (also known as plasma ashing) using oxygen gas as the etching gas.

[0205] By using the sacrificial layer 145b as a hard mask to etch the sacrificial film 144a, the photoresist mask 143a can be removed while the EL film 112Rf is covered by the sacrificial film 144a. In particular, when the EL film 112Rf is exposed to oxygen, it sometimes has a negative impact on its electrical properties, so it is preferable to use oxygen gas for etching such as plasma ashing.

[0206] Next, using the sacrificial layer 145b as a mask, the sacrificial film 144a is removed by etching to form an island-shaped or strip-shaped sacrificial layer 145a. Thus, a sacrificial layer 145R on which the sacrificial layer 145b is formed can be formed. Note that in a method for manufacturing a display device according to one embodiment of the present invention, neither the sacrificial layer 145a nor the sacrificial layer 145b may be used.

[0207] [Etching of EL film 112Rf] Next, a portion of the EL film 112Rf not covered by the sacrificial layer 145R is removed by etching to form an island-shaped or strip-shaped EL layer 112R (Fig. 10C).

[0208] Dry etching using an etching gas that does not contain oxygen as its main component can also be used when etching the EL film 112Rf. This suppresses deterioration of the EL film 112Rf, enabling a display device with high reliability. Examples of etching gases that do not contain oxygen as their main component include rare gases such as CF4, C4F8, SF6, CHF3, Cl2, H2, BCl3, or He. Alternatively, a mixture of the above gases and an oxygen-free diluent gas can be used as the etching gas. Here, a portion of the sacrificial layer 145b can also be removed during the etching of the EL film 112Rf.

[0209] Note that the etching of the EL film 112Rf is not limited to the above method. It can be done by dry etching using other gases or by wet etching.

[0210] Furthermore, when using an etching gas containing oxygen or dry etching with oxygen gas in the etching of the EL film 112Rf, the etching rate can be increased. Therefore, etching can be performed at low power conditions while maintaining a sufficient etching rate, thus reducing damage caused by etching. Also, defects such as the adhesion of reaction products occurring during etching can be suppressed. For example, an etching gas that is an etching gas containing oxygen as its main component can be used.

[0211] As described above, in this embodiment, the pixel electrode 111 has a tapered shape on its side. Therefore, during the etching process of the EL film 112Rf, even if the distance between adjacent pixel electrodes 111 is less than 1 μm, wall-like structures such as residues of the EL film 112Rf can be prevented from forming in the recesses between adjacent pixel electrodes 111. Therefore, in subsequent processes, the insulating layer 131, the common layer 114, and the common electrode 113 can be provided without the presence of corrugated structures between adjacent pixel electrodes 111. As a result, by depositing the common layer 114 and the common electrode 113 with high coverage, the display quality of the display device can be improved.

[0212] Furthermore, in the above-described process, when etching the EL film 112Rf using oxygen-containing gas, the surface conditions of the pixel electrode 111G and pixel electrode 111B sometimes change. For example, the surfaces of the pixel electrode 111G and pixel electrode 111B are hydrophilic. Here, the EL film formed in subsequent processes with a region in contact with the pixel electrode 111G and the EL film formed with a region in contact with the pixel electrode 111B are hydrophobic. Therefore, the adhesion between the pixel electrode 111G and pixel electrode 111B and the EL film formed in subsequent processes is low, and film peeling may occur.

[0213] Therefore, by performing a hydrophobic treatment on the surfaces of pixel electrode 111G and pixel electrode 111B, film peeling of the EL film formed in subsequent processes can be suppressed. This allows the display device 100 to be a highly reliable display device. Furthermore, it improves the yield rate during the manufacture of the display device 100 and reduces the manufacturing cost of the display device 100. The hydrophobic treatment is preferably performed before the formation of the EL film 112Gf and EL film 112Bf, which will be described later.

[0214] Hydrophobicity treatment can be performed, for example, by fluorine modification of pixel electrodes 111G and 111B. Fluorine modification can be performed, for example, by treatment with a fluorine-containing gas or by heat treatment, or by plasma treatment in a fluorine-containing gas atmosphere. Fluorine gases can be used as fluorine-containing gases, for example, fluorocarbon gases. Examples of fluorocarbon gases include low-grade fluorinated carbon gases such as carbon tetrafluoride (CF4), C4F6, C2F6, C4F8, and C5F8. Additionally, SF6, NF3, and CHF3 gases can be used as fluorine-containing gases. Furthermore, helium, argon, or hydrogen gases can be appropriately added to these gases.

[0215] Alternatively, the surfaces of pixel electrode 111G and pixel electrode 111B can be hydrophobized by performing plasma treatment on the surfaces of pixel electrode 111G and pixel electrode 111B in a gas atmosphere containing Group 18 elements such as argon, followed by treatment with a silanizing agent. Hexamethyldisilazane (HMDS) and trimethylsilimidazole (TMSI) can be used as silanizing agents. Furthermore, the surfaces of pixel electrode 111G and pixel electrode 111B can also be hydrophobized by performing plasma treatment on the surfaces of pixel electrode 111G and pixel electrode 111B in a gas atmosphere containing Group 18 elements such as argon, followed by treatment with a silane coupling agent. Treatment with silanizing agents or silane coupling agents can be performed, for example, by spin coating, dip coating, or vapor phase coating.

[0216] [Formation of EL layer 112G and EL layer 112B] Next, an EL film 112Gf, which forms the EL layer 112G, is deposited on the sacrificial layer 145R, the pixel electrode 111G, and the pixel electrode 111B. For details on the EL film 112Gf, please refer to the description of the EL film 112Rf.

[0217] Next, a sacrificial film 144G is deposited on the EL film 112Gf. For details on the sacrificial film 144G, please refer to the description of the sacrificial film 144R.

[0218] Next, a photoresist mask 143b is formed on the sacrificial film 144G (Fig. 10D).

[0219] Next, sacrificial layer 145G and EL layer 112G are formed. The formation of sacrificial layer 145G and EL layer 112G can refer to the formation of sacrificial layer 145R and EL layer 112R.

[0220] Next, an EL film 112Bf, which forms the EL layer 112B, is deposited on the sacrificial layer 145R, the sacrificial layer 145G, and the pixel electrode 111B. For details on the EL film 112Bf, please refer to the description of the EL film 112Rf.

[0221] Next, a sacrificial film 144B is deposited on the EL film 112Bf. For details on the sacrificial film 144B, please refer to the description of the sacrificial film 144R.

[0222] Next, a photoresist mask 143c is formed on the sacrificial film 144B (Fig. 10E).

[0223] Next, sacrificial layer 145B and EL layer 112B are formed (Fig. 10F). The formation of sacrificial layer 145B and EL layer 112B can refer to the formation of sacrificial layer 145R and EL layer 112R.

[0224] [Formation of Insulating Layer 131] Next, an insulating film 131bf (FIG. 11A) is formed to become the insulating layer 131b. The insulating film 131bf is preferably a film containing inorganic materials. For example, the insulating film 131bf can be a single layer or a stack of films including aluminum oxide, magnesium oxide, hafnium oxide, gallium oxide, indium gallium zinc oxide, silicon oxide, silicon oxynitride, silicon nitride, or silicon oxynitride.

[0225] The insulating film 131bf can be formed by sputtering, chemical vapor deposition (CVD), molecular beam epitaxy (MBE), pulsed laser deposition (PLD), atomic layer deposition (ALD), etc. The insulating film 131bf is suitable for formation using the ALD method, which has good coverage.

[0226] The insulating film 131bf can be a single layer or a stack of materials such as aluminum oxide, magnesium oxide, hafnium oxide, gallium oxide, indium gallium zinc oxide, silicon oxide, silicon oxynitride, silicon nitride, or silicon oxynitride. In particular, aluminum oxide has a high selectivity to the EL layer 112 during etching and has a protective function for the EL layer 112 during the formation of the subsequent insulating layer 131b, so it is preferred.

[0227] By using the ALD method to form an insulating film 131bf, a film with fewer pinholes can be achieved, and an insulating layer 131b with excellent protection function for the EL layer 112 can be achieved.

[0228] Furthermore, it is preferable to form the insulating film 131bf at a deposition temperature lower than the heat resistance temperature of the EL layer 112. For example, it is preferable to form the insulating film 131bf using the ALD method to form alumina. The formation temperature of the insulating film 131bf using the ALD method is preferably 60°C or higher and 150°C or lower, more preferably 70°C or higher and 115°C or lower, and even more preferably 80°C or higher and 100°C or lower. By forming the insulating film 131bf at this temperature, a dense insulating film can be obtained and damage to the EL layer 112 can be reduced.

[0229] Furthermore, the insulating film 131bf may also have a stacked structure. For example, as shown in FIG4B, the insulating film 131bf may also have a stacked structure of an alumina film deposited by the ALD method and a silicon nitride film deposited by sputtering. By providing a silicon nitride film, the barrier properties of the insulating film 131bf can be further improved. In addition, since the silicon nitride film is deposited on the alumina film by sputtering, damage to the EL layer 112 and the like can be reduced.

[0230] Next, an insulating film 131af (FIG. 11B) is formed as an insulating layer 131a. The insulating film 131af is provided in such a way that it fills the recesses of the insulating film 131bf. The insulating film 131af is provided in such a way that it covers the sacrificial layer 145, the EL layer 112, and the pixel electrode 111. The insulating film 131af is preferably a planarization film.

[0231] As the insulating film 131af, it is preferable to use an insulating film containing organic materials, and resin is preferably used as the organic material.

[0232] Examples of materials that can be used in the insulating film 131af include acrylic resin, polyimide resin, epoxy resin, polyimide resin, polyimide-polyamide resin, silicone resin, benzocyclobutene resin, phenolic resin, and precursors of the above resins. Furthermore, a photosensitive resin can be used as the insulating film 131af. The photosensitive resin can be either a positive or negative material.

[0233] When the insulating film 131af is formed using photosensitive resin, the insulating layer 131a can be manufactured by only exposure and development processes, which can reduce damage to the layers constituting the light-emitting element 110, especially the EL layer.

[0234] As shown in Figure 11B, the insulating film 131af sometimes has a gentle unevenness that reflects the unevenness of the surface to be formed. Alternatively, sometimes the insulating film 131af is less affected by the unevenness of the surface to be formed, and the flatness of the insulating film 131af is higher than that in Figure 11B.

[0235] Next, an insulating layer 131a is formed. Here, by using a photosensitive resin as the insulating film 131af, the insulating layer 131a can be formed without the need for etching masks such as photoresist masks or hard masks. The photosensitive resin can only be processed through exposure and development processes, so the insulating layer 131a can be formed without the use of dry etching methods. Therefore, the process can be simplified. In addition, the damage to the EL layer caused by etching of the insulating film 131af can be reduced. Furthermore, a portion of the upper part of the insulating layer 131a can be further etched to adjust the surface height.

[0236] Alternatively, the top surface of the insulating film 131af can be etched approximately uniformly to form the insulating layer 131a. This uniform etching and planarization process is called a back etching process. Here, the back etching of the insulating film 131af can be performed, for example, by ashing using oxygen plasma.

[0237] When forming the insulating layer 131a, the exposure and development process and the etching process can also be used in combination.

[0238] An example of a method for forming insulating layer 131a will be illustrated using Figures 11C and 11D. Figure 11C shows an example of forming insulating layer 131ap by processing insulating film 131af as insulating film 131af using a photosensitive resin and undergoing exposure and development. By further etching back the insulating layer 131ap shown in Figure 11C, the insulating layer 131a shown in Figure 11D can be formed.

[0239] Note that the insulating film 131bf can also be etched back during the formation of the insulating layer 131a. The etch-back of the insulating film 131bf can be performed using dry etching or wet etching. Alternatively, etching can be performed using oxygen plasma ashing or the like. Furthermore, chemical mechanical polishing (CMP) can also be used for the etch-back of the insulating film 131bf.

[0240] Here, the insulating layer 131a may sometimes be in the shape of a concave surface (recessed shape) or a convex surface (protruding shape) in the region between multiple EL layers 112.

[0241] Alternatively, the insulating layer 131ap shown in FIG11C can also be used as the insulating layer 131a. In this case, as shown in FIG4A, the light-emitting element 110 sometimes has a structure in which the insulating layer 131a and the top surface of the EL layer 112 have a residual sacrificial layer 145a and sacrificial layer 145b.

[0242] [Etching of insulating film 131bf and sacrificial layer 145] Next, the region above the top surface of insulating layer 131a of insulating film 131bf, sacrificial layer 145R, sacrificial layer 145G and sacrificial layer 145B (hereinafter collectively referred to as sacrificial layer 145) is removed by etching or the like (Fig. 11E).

[0243] Thus, the top surface of the EL layer 112 is exposed, and an insulating layer 131b is formed between each EL layer 112. The insulating layer 131b is formed in such a way that it covers the sides of the EL layer 112 and the pixel electrode 111. Thus, oxygen, moisture or their constituent elements can be suppressed from diffusing directly from the insulating layer 131a to the EL layer 112.

[0244] The etching of the insulating film 131bf and the sacrificial layer 145 can be performed using dry etching or wet etching.

[0245] Here, in the etching of the sacrificial layer 145, it is preferable to etch the sacrificial layer 145a after etching the sacrificial layer 145b. At this time, in the etching of the sacrificial layer 145b, it is preferable to use a condition with a higher selectivity than that of the sacrificial layer 145a.

[0246] In the etching of the sacrificial layer 145a, it is preferable to use a method that minimizes damage to the EL layers 112R, EL layers 112G, and EL layers 112B. For example, using an inorganic material as the sacrificial layer 145a can sometimes improve the selectivity to the EL layer 112.

[0247] [Forming of Common Layer 114] Next, the common layer 114 is formed. Note that if a structure is adopted in which the common layer 114 is not provided on the connecting electrode 111C, a metal mask that covers the connecting electrode 111C can be used when depositing the common layer 114. It is not necessary to cover the pixel area of ​​the display unit with the metal mask used at this time, so a high-resolution mask is not required.

[0248] The common layer 114 is formed using a material having one or more functions selected from: the function of injecting one or both of electrons and holes into the EL layer, the function of transporting electrons and holes, and the function of suppressing electrons and holes. More specifically, the common layer 114 includes at least one of a hole injection layer, a hole transport layer, a hole barrier layer, an electron barrier layer, an electron transport layer, and an electron injection layer.

[0249] [Formation of common electrode 113] Next, a common electrode 113 is formed on the common layer 114. The common electrode 113 can be formed, for example, by sputtering or vacuum evaporation. Note that, without the common layer 114, the common electrode 113 can be formed by covering the EL layers 112R, EL layers 112G and EL layers 112B.

[0250] The above process can be used to manufacture light-emitting elements 110R, 110G and 110B.

[0251] [Formation of Protective Layer 121] Next, a protective layer 121 is formed on the common electrode 113 (FIG. 1B). When depositing the inorganic insulating film for the protective layer 121, sputtering, PECVD, or ALD methods are preferred. In particular, ALD is preferred because it provides good step coverage and is less prone to defects such as pinholes. Alternatively, when depositing an organic insulating film, inkjet printing is preferred because it allows for uniform film formation in the desired area.

[0252] The display device 100 shown in FIG1A to FIG1C can be manufactured by the above process.

[0253] At least a portion of this embodiment may be implemented in combination with other embodiments described in this specification.

[0254] Embodiment 2 In this embodiment, an example of the structure of a display device according to an embodiment of the present invention will be described.

[0255] The display device of this embodiment can be a high-resolution display device or a large-screen display device. Therefore, the display device of this embodiment can be used as a display unit for devices such as: electronic devices with large screens, such as televisions, desktop or laptop computers, monitors for computers, digital signage, large game consoles such as pinball machines, etc.; digital cameras; digital video cameras; digital photo frames; mobile phones; portable game consoles; smartphones; watch-type terminals; tablet terminals; portable information terminals; and audio playback devices.

[0256] [Example of the structure of a display device] Figure 12 shows a perspective view of the display device 400A, and Figure 13A shows a cross-sectional view of the light-emitting device 400A.

[0257] The display device 400A has a structure in which a substrate 452 and a substrate 451 are bonded together. In FIG12, the substrate 452 is indicated by a dashed line.

[0258] The display device 400A includes a display unit 462, a circuit 464, and wiring 465, etc. Figure 12 shows an example in which an IC 473 and an FPC 472 are installed in the display device 400A. Therefore, the structure shown in Figure 12 can also be referred to as a display module including the display device 400A, an IC (integrated circuit), and an FPC.

[0259] As circuit 464, for example, a scan line drive circuit can be used.

[0260] Wiring 465 has the function of supplying signals and power to display unit 462 and circuit 464. The signals and power are input to wiring 465 from the outside via FPC 472 or from IC 473.

[0261] Figure 12 shows an example of IC 473 being mounted on substrate 451 using COG (Chip On Glass) or COF (Chip on Film) methods. IC 473 can be, for example, an IC including scan line drive circuitry or signal line drive circuitry. Note that the display device 400A and the display module do not necessarily need to have an IC mounted on them. Alternatively, the IC can be mounted on an FPC using COF or similar methods.

[0262] FIG13A shows an example of a cross-section of a portion of the display device 400A including the region of FPC 472, a portion of the circuit 464, a portion of the display section 462, and a portion of the region including the end.

[0263] The display device 400A shown in FIG13A includes transistor 201, transistor 205, light-emitting element 430a emitting red light, light-emitting element 430b emitting green light, and light-emitting element 430c emitting blue light between substrate 451 and substrate 452.

[0264] The light-emitting elements 430a, 430b and 430c can be the light-emitting elements illustrated in Embodiment 1.

[0265] Here, when the pixels of the display device include three sub-pixels having light-emitting elements that emit light differently from each other, examples of the three sub-pixels are sub-pixels of three colors: R, G, and B, and sub-pixels of three colors: yellow (Y), cyan (C), and magenta (M). When four of the above-mentioned sub-pixels are included, examples of the four sub-pixels are sub-pixels of four colors: R, G, B, and white (W), and sub-pixels of four colors: R, G, B, and Y.

[0266] The protective layer 410 and the substrate 452 are bonded together by the adhesive layer 442. As a seal for the light-emitting element, a solid sealing structure or a hollow sealing structure can be used. In Figure 13, the space 443 surrounded by the substrate 452, the adhesive layer 442, and the substrate 451 is filled with an inert gas (nitrogen or argon, etc.), employing a hollow sealing structure. The adhesive layer 442 may also overlap with the light-emitting element. Furthermore, the space 443 surrounded by the substrate 452, the adhesive layer 442, and the substrate 451 may also be filled with a resin different from the adhesive layer 442.

[0267] Conductive layers 418a, 418b, and 418c are formed in the opening in the insulating layer 214 such that the top surface of the conductive layer 222b included in the transistor 205 is exposed. A portion of the conductive layers 418a, 418b, and 418c are formed along the bottom and side surfaces of the opening. The conductive layers 418a, 418b, and 418c are connected to the conductive layer 222b included in the transistor 205 through the opening in the insulating layer 214. The pixel electrode contains a material that reflects visible light, and the counter electrode contains a material that transmits visible light. Other portions of the conductive layers 418a, 418b, and 418c are disposed on the insulating layer 214.

[0268] Pixel electrodes 411a, 411b, and 411c are provided on conductive layers 418a, 418b, and 418c. Pixel electrodes 111 shown in the above embodiment can be used as pixel electrodes 411a, 411b, and 411c.

[0269] In addition, as shown in FIG13A, an insulating layer 414 may also be provided between each of the conductive layers 418a, 418b and 418c and between each of the pixel electrodes 411a, 411b and 411c.

[0270] In addition, the pixel electrodes 411a, 411b and 411c are provided with the EL layer 416a included in the light-emitting element 430a, the EL layer 416b included in the light-emitting element 430b and the EL layer 416c included in the light-emitting element 430c.

[0271] An insulating layer 421 is provided in the region between the light-emitting elements 430a and 430b and on the insulating layer 214, and in the region between the light-emitting elements 430b and 430c and on the insulating layer 214. The insulating layer 421 can refer to the insulating layers 131a and 131b shown in the above embodiments.

[0272] Furthermore, a common layer 424 is provided to cover the EL layers 416a, 416b, 416c and the insulating layer 416. The common layer 424 can be the common layer 114 shown in the above embodiments. A common electrode 423 is provided on the common layer 424. The common electrode 113 shown in the above embodiments can be the common electrode 423.

[0273] The light-emitting element emits light onto one side of the substrate 452. The substrate 452 is preferably made of a material with high transmittance to visible light.

[0274] Transistors 201 and 205 are both disposed on substrate 451. These transistors can be formed using the same material and the same process.

[0275] Insulating layers 211, 213, 215, and 214 are sequentially disposed on substrate 451. A portion of insulating layer 211 serves as a gate insulating layer for each transistor. A portion of insulating layer 213 serves as a gate insulating layer for each transistor. Insulating layer 215 is disposed to cover the transistor. Insulating layer 214 is disposed to cover the transistor and serves as a planarization layer. Furthermore, there is no particular limitation on the number of gate insulating layers and the number of insulating layers covering the transistor; there can be one or more.

[0276] Preferably, at least one of the insulating layers covering the transistor is made of a material that does not readily diffuse impurities such as water and hydrogen. This allows the insulating layer to function as a barrier layer. By employing this structure, the diffusion of impurities from the outside into the transistor can be effectively suppressed, thereby improving the reliability of the display device.

[0277] Inorganic insulating films are preferably used as insulating layers 211, 213, and 215. Examples of inorganic insulating films include silicon nitride films, silicon oxynitride films, silicon oxide films, silicon oxynitride films, aluminum oxide films, and aluminum nitride films. Additionally, hafnium oxide films, yttrium oxide films, zirconium oxide films, gallium oxide films, tantalum oxide films, magnesium oxide films, lanthanum oxide films, cerium oxide films, and neodymium oxide films can also be used. Furthermore, two or more of the above-mentioned insulating films can be laminated.

[0278] The insulating layer 214 used as the planarization layer is preferably an organic insulating film. Materials suitable for use as organic insulating films include, for example, acrylic resin, polyimide resin, epoxy resin, polyimide resin, polyimide-polyamide resin, silicone resin, benzocyclobutene resin, phenolic resin, and precursors of the above resins.

[0279] Here, the barrier properties of organic insulating films are often lower than those of inorganic insulating films. Therefore, it is preferable that the organic insulating film includes an opening near the end of the display device 400A. This can suppress impurities from entering through the organic insulating film from the end of the display device 400A. Alternatively, the organic insulating film can be formed with its end located inside the end of the display device 400A, so that the organic insulating film is not exposed at the end of the display device 400A.

[0280] In region 228 shown in FIG13A, an opening is formed in the two-layer stacked structure of insulating layer 214 and insulating layer 421b on insulating layer 214. Insulating layer 421b can be formed using the same material as insulating layer 421. In addition, insulating layer 421b is formed, for example, by the same process as insulating layer 421. Protective layer 410 is formed to cover the opening. By using an inorganic layer as protective layer 410, even if an organic insulating film is used for insulating layer 214, impurities can be prevented from entering the display section 462 from the outside through insulating layer 214. Therefore, the reliability of display device 400A can be improved.

[0281] FIG13B shows an enlarged view of transistors 201 and 205. Transistors 201 and 205 include: a conductive layer 221 serving as a gate; an insulating layer 211 serving as a gate insulating layer; a semiconductor layer 231 including a channel forming region 231i and a pair of low-resistance regions 231n; a conductive layer 222a connected to one of the pair of low-resistance regions 231n; a conductive layer 222b connected to the other of the pair of low-resistance regions 231n; an insulating layer 213 serving as a gate insulating layer; a conductive layer 223 serving as a gate; and an insulating layer 215 covering the conductive layer 223. One of the conductive layers 222a and 222b is used as a source, and the other is used as a drain. The insulating layer 211 is located between the conductive layer 221 and the channel forming region 231i. The insulating layer 213 is located between the conductive layer 223 and the channel forming region 231i.

[0282] There are no particular limitations on the transistor structure included in the display device of this embodiment. For example, a planar transistor, an interlaced transistor, or an anti-interlaced transistor may be used. Furthermore, the transistor may have a top-gate structure or a bottom-gate structure. Alternatively, gates may be provided above and below the semiconductor layer forming the channel.

[0283] Transistors 201 and 205 employ a structure in which a semiconductor layer forming a channel is sandwiched between two gates. Alternatively, the two gates can be connected, and the transistor can be driven by supplying the same signal to both gates. Or, the critical voltage of the transistor can be controlled by applying a potential to one of the two gates to control the critical voltage and applying a potential to the other to drive it.

[0284] There are no particular restrictions on the crystallinity of the semiconductor material used for the transistor. Amorphous semiconductors and crystalline semiconductors (microcrystalline semiconductors, polycrystalline semiconductors, single-crystal semiconductors, or semiconductors in which a portion has crystalline regions) can be used. When using crystalline semiconductors, the degradation of transistor characteristics can be suppressed, so it is preferable.

[0285] The semiconductor layer of the transistor is preferably made of metal oxide (also known as oxide semiconductor). That is, the display device of this embodiment preferably uses a transistor (hereinafter, OS transistor) that uses metal oxide in the channel forming region. In addition, the semiconductor layer of the transistor may also contain silicon. Examples of silicon include amorphous silicon, crystalline silicon (low-temperature polycrystalline silicon, monocrystalline silicon, etc.).

[0286] For example, the semiconductor layer preferably comprises indium, M (M being one or more selected from gallium, aluminum, silicon, boron, yttrium, tin, copper, vanadium, beryllium, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, and magnesium) and zinc. In particular, M is preferably one or more selected from aluminum, gallium, yttrium, and tin.

[0287] In particular, as the semiconductor layer, it is preferable to use an oxide containing indium (In), gallium (Ga), and zinc (Zn) (also described as IGZO). Alternatively, as the semiconductor layer, an oxide containing indium (In), aluminum (Al), and zinc (Zn) (also described as IAZO) may also be used. Alternatively, as the semiconductor layer, an oxide containing indium (In), aluminum (Al), gallium (Ga), and zinc (Zn) (IAGZO) may also be used.

[0288] When the semiconductor layer is an In-M-Zn oxide, the atomic ratio of In in the In-M-Zn oxide is preferably greater than or equal to the atomic ratio of M. Examples of such atomic ratios of metal elements in the In-M-Zn oxide include: In:M:Zn = 1:1:1 or similar; In:M:Zn = 1:1:1.2 or similar; In:M:Zn = 1:3:2 or similar; In:M:Zn = 1:3:4 or similar; In:M:Zn = 2:1:3 or similar; In:M:Zn = 3:1:2 or similar; and In:M:Zn = 4:5. Compositions with an atomic ratio of 4:2:3 or similar, including In:M:Zn = 4:2:4.1 or similar, In:M:Zn = 5:1:3 or similar, In:M:Zn = 5:1:6 or similar, In:M:Zn = 5:1:7 or similar, In:M:Zn = 5:1:8 or similar, In:M:Zn = 6:1:6 or similar, In:M:Zn = 5:2:5 or similar, etc. Furthermore, "simultaneous" composition includes a range of ±30% of the desired atomic ratio.

[0289] When the atomic number ratio is described as In:Ga:Zn = 4:2:3 or similar, the following cases are included: when In is 4, Ga is 1 or more and 3 or less, and Zn is 2 or more and 4 or less. Furthermore, when the atomic number ratio is described as In:Ga:Zn = 5:1:6 or similar, the following cases are included: when In is 5, Ga is greater than 0.1 and 2 or less, and Zn is 5 or more and 7 or less. Furthermore, when the atomic number ratio is described as In:Ga:Zn = 1:1:1 or similar, the following cases are included: when In is 1, Ga is greater than 0.1 and 2 or less, and Zn is greater than 0.1 and 2 or less.

[0290] The transistors included in circuit 464 and the transistors included in display unit 462 may have the same structure or different structures. The multiple transistors included in circuit 464 may have the same structure or two or more different structures. Similarly, the multiple transistors included in display unit 462 may have the same structure or two or more different structures.

[0291] A connection portion 204 is provided in a region of the substrate 451 that does not overlap with the substrate 452. In the connection portion 204, wiring 465 is electrically connected to the FPC 472 via a conductive layer 466 and a connection layer 242. The conductive layer 466 can be a conductive film obtained by processing the same conductive film as the pixel electrode, or a conductive film obtained by processing a laminated film of the same conductive film as the pixel electrode and a conductive film of the same conductive film as the optical adjustment layer. The conductive layer 466 is exposed on the top surface of the connection portion 204. Therefore, the connection portion 204 can be electrically connected to the FPC 472 via the connection layer 242.

[0292] Preferably, a light-shielding layer 417 is provided on the surface of the substrate 452 on the substrate 451 side. Furthermore, various optical components can be disposed on the outer side of the substrate 452. Examples of optical components include polarizing plates, retardation plates, light diffusion layers (diffusion films, etc.), anti-reflective layers, and condensing films. Additionally, an antistatic film that inhibits dust adhesion, a water-repellent film that is not easily soiled, a hard coating film that inhibits damage during use, and an impact-absorbing layer can also be disposed on the outer side of the substrate 452.

[0293] By forming a protective layer 410 covering the light-emitting element, impurities such as water can be prevented from entering the light-emitting element, thereby improving the reliability of the light-emitting element.

[0294] In the region 228 near the end of the display device 400A, it is preferable that the insulating layer 215 and the protective layer 410 are in contact with each other through an opening in the insulating layer 214. In particular, it is especially preferable that the inorganic insulating film contained in the insulating layer 215 and the inorganic insulating film contained in the protective layer 410 are in contact with each other. As a result, impurities can be prevented from entering the display section 462 from the outside through the organic insulating film. Therefore, the reliability of the display device 400A can be improved.

[0295] Substrates 451 and 452 can be made of glass, quartz, ceramic, sapphire, resin, metal, alloy, semiconductor, etc. The substrate on the side from which light is extracted from the light-emitting element uses a material that allows the light to pass through. In addition, by using a flexible material for substrates 451 and 452, the flexibility of the display device can be improved, and a flexible display can be realized. A polarizing plate can also be used as substrate 451 or substrate 452.

[0296] The following materials can be used as substrates 451 and 452: polyester resins such as polyethylene terephthalate (PET) or polyethylene naphthalate (PEN), polyacrylonitrile resin, acrylic resin, polyimide resin, polymethyl methacrylate resin, polycarbonate (PC) resin, polyether ether (PES) resin, polyamide resin (nylon, aromatic polyamide, 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, and cellulose nanofibers, etc. One or both of substrates 451 and 452 can also be made of glass with a flexible thickness.

[0297] When a circular polarizer is superimposed on a display device, it is preferable to use a substrate with high optical isotropy as the substrate included in the display device. The substrate with high optical isotropy has lower birefringence (or, in other words, less birefringence).

[0298] The absolute value of the retardation value of the substrate with high optical isotropy is preferably 30 nm or less, more preferably 20 nm or less, and even more preferably 10 nm or less.

[0299] Among thin films with high optical isotropy, examples include cellulose triacetate (TAC) films, cyclic olefin polymer (COP) films, cyclic olefin copolymer (COC) films, and acrylic films.

[0300] When a thin film is used as a substrate, the display panel may experience shape changes such as wrinkles due to water absorption by the film. Therefore, it is preferable to use a thin film with a low water absorption rate as the substrate. For example, it is preferable to use a thin film with a water absorption rate of 1% or less, more preferably a thin film with a water absorption rate of 0.1% or less, and even more preferably a thin film with a water absorption rate of 0.01% or less.

[0301] As the adhesive layer, various curing adhesives can be used, such as UV-curing adhesives, reaction-curing adhesives, thermosetting adhesives, and anaerobic adhesives. Examples of these adhesives include epoxy resins, acrylic resins, silicone resins, phenolic resins, polyimide resins, PVC (polyvinyl chloride) resins, PVB (polyvinyl butyral) resins, and EVA (ethylene vinyl acetate) resins. In particular, materials with low moisture permeability, such as epoxy resins, are preferred. Furthermore, two-component mixed resins can also be used. Additionally, adhesive sheets can also be used.

[0302] As the connecting layer 242, anisotropic conductive film (ACF) or anisotropic conductive paste (ACP) can be used.

[0303] Materials that can be used as gates, sources, and drains of transistors, as well as conductive layers such as wiring and electrodes constituting display devices, include metals such as aluminum, titanium, chromium, nickel, copper, yttrium, zirconium, molybdenum, silver, tantalum, or tungsten, or alloys with the above metals as the main component. Single layers or stacks of films containing these materials can be used.

[0304] Furthermore, as a conductive material with light transmittance, conductive oxides such as indium oxide, indium tin oxide, indium zinc oxide, zinc oxide, and zinc oxide containing gallium, or graphene, can be used. Alternatively, metallic materials such as gold, silver, platinum, magnesium, nickel, tungsten, chromium, molybdenum, iron, cobalt, copper, palladium, or titanium, or alloy materials containing such metallic materials, can be used. Alternatively, nitrides of the metallic materials (e.g., titanium nitride) can also be used. Furthermore, when using metallic or alloy materials (or their nitrides), it is preferable to form them thin enough to be light transmittant. In addition, a multilayer film of the above-mentioned materials can be used as a conductive layer. For example, by using a multilayer film of an alloy of silver and magnesium with indium tin oxide, conductivity can be improved, so it is preferable. The above-mentioned materials can also be used as conductive layers constituting various wirings and electrodes of a display device, and as conductive layers included in light-emitting elements (conductive layers used as pixel electrodes or common electrodes).

[0305] As insulating materials that can be used in various insulating layers, examples include resins such as acrylic resin or epoxy resin, and inorganic insulating materials such as silicon oxide, silicon oxynitride, silicon oxynitride, silicon nitride, or aluminum oxide.

[0306] Figure 13C shows an example in which the insulating layer 213 covers the top and side surfaces of the semiconductor layer in transistors 201 and 205. Conductive layers 222a and 222b are connected to the low-resistance region 231n through openings provided in the insulating layers 213 and 215.

[0307] On the other hand, in the transistor 209 shown in FIG13D, the insulating layer 213 overlaps with the channel forming region 231i of the semiconductor layer 231 but does not overlap with the low resistance region 231n. For example, the structure shown in FIG13D can be formed by processing the insulating layer 213 with the conductive layer 223 as a mask. In FIG13D, the insulating layer 215 is provided in such a way that it covers the insulating layer 213 and the conductive layer 223, and the conductive layers 222a and 222b are respectively connected to the low resistance region 231n through the opening of the insulating layer 215. Furthermore, an insulating layer 218 covering the transistor may also be provided.

[0308] The transistors included in the pixel circuit that drive the light-emitting element can all be transistors containing silicon in the semiconductor layer in which the channel is formed (hereinafter also referred to as Si transistors). Examples of silicon include monocrystalline silicon, polycrystalline silicon, and amorphous silicon. In particular, transistors containing low-temperature polysilicon (LTPS) in the semiconductor layer (hereinafter also referred to as LTPS transistors) can be used. LTPS transistors have high field-effect mobility and good frequency characteristics.

[0309] By using silicon-based transistors such as LTPS transistors, circuits requiring high-frequency driving (e.g., source driver circuits) and display sections can be formed on the same substrate. Therefore, the external circuitry mounted to the display device can be simplified, and component and installation costs can be reduced.

[0310] Furthermore, it is preferable to use at least one of the transistors included in the pixel circuit, which contains a metal oxide (hereinafter also referred to as an oxide semiconductor) in the semiconductor layer in which the channel is formed. The field-effect mobility of the OS transistor is much higher than that of amorphous silicon. In addition, the leakage current between the source and drain of the OS transistor in the off state (hereinafter also referred to as the off-state current) is extremely low, which can maintain the charge stored in the capacitor connected in series with the transistor for a long time. In addition, by using the OS transistor, the power consumption of the display device can be reduced.

[0311] Furthermore, the off-state current of an OS transistor with a channel width of 1 μm at room temperature can be less than 1aA (1×10⁻¹⁸ A), less than 1zA (1×10⁻²¹ A), or less than 1yA (1×10⁻²⁴ A). Note that the off-state current of a Si transistor with a channel width of 1 μm at room temperature is greater than or equal to 1fA (1×10⁻¹⁵ A) and less than 1pA (1×10⁻¹² A). Therefore, it can also be said that the off-state current of an OS transistor is about 10 bits lower than that of a Si transistor.

[0312] Furthermore, when increasing the luminous brightness of the light-emitting element included in the pixel circuit, it is necessary to increase the current flowing through the light-emitting element. For this purpose, it is necessary to increase the source-drain voltage of the driving transistor included in the pixel circuit. Because the source-drain breakdown voltage of an OS transistor is higher than that of a Si transistor, a high voltage can be applied between the source and drain of the OS transistor. Therefore, by using an OS transistor as the driving transistor included in the pixel circuit, the current flowing through the light-emitting element can be increased, thereby improving the luminous brightness of the light-emitting element.

[0313] Furthermore, when the transistor operates in the saturation region, compared to a Si transistor, an OS transistor can make the change in source-drain current relative to the change in gate-source voltage smaller. Therefore, by using an OS transistor as the driving transistor included in the pixel circuit, the current flowing through the source-drain can be determined in detail according to the change in gate-source voltage, thus controlling the amount of current flowing through the light-emitting element. As a result, the grayscale of the pixel circuit can be increased.

[0314] Furthermore, regarding the saturation characteristics of the current flowing through a transistor when it operates in the saturation region, compared to a Si transistor, an OS transistor can maintain a stable current (saturation current) even when the source-drain voltage is gradually increased. Therefore, by using an OS transistor as a driving transistor, even if the current-voltage characteristics of a light-emitting element containing, for example, EL material become non-uniform, a stable current can still flow through the light-emitting element. In other words, when an OS transistor operates in the saturation region, the source-drain current remains almost unchanged even when the source-drain voltage is increased, thus stabilizing the luminous brightness of the light-emitting element.

[0315] As described above, by using an OS transistor as the driving transistor included in the pixel circuit, it is possible to achieve "suppression of black blur", "increase in light emission brightness", "multi-grayscale conversion", "suppression of uneven light emission elements", etc.

[0316] By using LTPS transistors as a part of the transistors included in the pixel circuit and OS transistors as other transistors, a display device with low power consumption and high driving capability can be realized. Sometimes, the structure combining LTPS transistors and OS transistors is called LTPO. As a better example, it is preferable to use OS transistors as transistors used as switches to control the conduction / non-conduction between wirings and LTPS transistors as transistors to control current.

[0317] For example, one of the transistors provided in the pixel circuit is used as a transistor to control the current flowing through the light-emitting element, and therefore can also be called a driving transistor. One of the source and drain electrodes of this driving transistor is electrically connected to the pixel electrode of the light-emitting element. Preferably, an LTPS transistor is used as this driving transistor. This increases the current flowing through the light-emitting element in the pixel circuit.

[0318] On the other hand, another transistor provided in the pixel circuit is used as a switch to control the selection / non-selection of pixels, and therefore can be called a selection transistor. The gate of the selection transistor is electrically connected to the gate line, and one of the source and drain is electrically connected to the source line (signal line). It is preferable to use an OS transistor as the selection transistor. As a result, even if the frame frequency is greatly reduced (for example, to less than 1 fps), the grayscale of the pixel can be maintained, so the driver is stopped when displaying still images, thereby reducing power consumption.

[0319] Thus, in one embodiment of the present invention, a display device that combines high aperture ratio, high definition, high display quality and low power consumption can be realized.

[0320] Note that the display device of one embodiment of the present invention employs a structure including an OS transistor and a light-emitting element having an MML (Metal Mask Less) structure. By employing this structure, the leakage current flowing through the transistor and the leakage current flowing between adjacent light-emitting elements (also known as lateral leakage current, side leakage current, etc.) can be extremely low. In addition, by employing the above structure, when an image is displayed on the display device, the viewer can observe one or more of the following: image sharpness, image sharpness, high color saturation, and high contrast. Furthermore, by employing a structure with extremely low leakage current flowing through the transistor and extremely low lateral leakage current between light-emitting elements, minimal light leakage (so-called whitening) that can occur when displaying black can be achieved (also known as pure black display).

[0321] At least a portion of the structural examples shown in this embodiment and the corresponding diagrams can be appropriately combined with other structural examples or diagrams.

[0322] Embodiment 3 In this embodiment, an example of a display device structure that is different from the above will be described.

[0323] The display device of this embodiment can be a high-definition display device. Therefore, for example, the display device of this embodiment can be used as the display part of wearable devices that can be worn on the head, such as watch-type or bracelet-type information terminal devices (wearable devices), VR devices such as head-mounted displays, and AR devices such as glasses-type displays.

[0324] [Display Module] Figure 14A is a perspective view of display module 280. Display module 280 includes display device 400C and FPC 290. Note that the display device included in display module 280 is not limited to display device 400C, but may also be display device 400D, display device 400E or display device 400F, which will be described later.

[0325] The display module 280 includes a substrate 291 and a substrate 292. The display module 280 includes a display section 281. The display section 281 is an image display area in the display module 280, and can see light from each pixel disposed in the pixel section 284 described below.

[0326] FIG14B is a perspective view of the structure of one side of the substrate 291. A circuit section 282, a pixel circuit section 283 on the circuit section 282, and a pixel section 284 on the pixel circuit section 283 are stacked on the substrate 291. In addition, a terminal section 285 for connecting to the FPC 290 is provided on the portion of the substrate 291 that does not overlap with the pixel section 284. The terminal section 285 and the circuit section 282 are electrically connected by a wiring section 286 composed of multiple wirings.

[0327] The pixel unit 284 includes a plurality of pixels 284a arranged periodically. An enlarged view of a pixel 284a is shown on the right side of FIG14B. Pixel 284a includes light-emitting elements 430a, 430b, and 430c that emit different colors from each other. The plurality of light-emitting elements are preferably arranged in a stripe arrangement as shown in FIG14B. By employing a stripe arrangement, the light-emitting elements of one embodiment of the present invention can be arranged in a high density in the pixel circuit, thus providing a high-definition display device. In addition, various arrangement methods such as Delta arrangement and Pentile arrangement can also be used.

[0328] The pixel circuit section 283 includes a plurality of pixel circuits 283a arranged periodically.

[0329] A pixel circuit 283a controls the light emission of the three light-emitting elements included in a pixel 284a. A pixel circuit 283a may contain three circuits controlling the light emission of one light-emitting element. For example, the pixel circuit 283a may have a structure that includes at least one selection transistor, one current control transistor (driving transistor), and a capacitor for each light-emitting element. In this case, the gate of the selection transistor is input with a gate signal, and either the source or drain is input with a source signal. This realizes an active matrix display device.

[0330] The circuit section 282 includes circuitry for each pixel circuit 283a of the driving pixel circuit section 283. For example, it is preferably one or both of a gate line driving circuit and a source line driving circuit. In addition, it may also include at least one of an arithmetic circuit, a memory circuit, and a power supply circuit.

[0331] The FPC290 is used for wiring to supply video signals or power potentials, etc., from the outside to the circuit section 282. In addition, ICs can also be mounted on the FPC290.

[0332] The display module 280 can adopt a structure in which one or both of the pixel circuit section 283 and the circuit section 282 are stacked on the lower side of the pixel section 284, so that the display section 281 can have an extremely high aperture ratio (effective display area ratio). For example, the aperture ratio of the display section 281 can be 40% or more and less than 100%, preferably 50% or more and less than 95%, more preferably 60% or more and less than 95%. In addition, the pixels 284a can be arranged in an extremely high density, thereby enabling the display section 281 to have extremely high resolution. For example, the display section 281 is preferably arranged with a resolution of 20,000 ppi or less, or 30,000 ppi or less and 2,000 ppi or more, more preferably 3,000 ppi or more, further preferably 5,000 ppi or more, and even more preferably 6,000 ppi or more.

[0333] This ultra-high definition display module 280 is suitable for use in VR devices such as head-mounted displays or AR devices such as glasses. For example, because the display module 280 has an ultra-high definition display section 281, even when the display section of the display module 280 is viewed through a lens, the user cannot see the pixels, thus achieving a highly immersive display. Furthermore, the display module 280 can also be applied to electronic devices with relatively small display sections. For example, it is suitable for use in the display section of wearable electronic devices such as watch-type devices.

[0334] [Display Device 400C] The display device 400C shown in FIG15 includes a substrate 301, light-emitting elements 430a, 430b, 430c, a capacitor 240, and a transistor 310.

[0335] Transistor 310 is a transistor having a channel forming region in substrate 301. Substrate 301 can be, for example, a semiconductor substrate such as a single-crystal silicon substrate. Transistor 310 includes a portion of substrate 301, a conductive layer 311, a low-resistance region 312, an insulating layer 313, and an insulating layer 314. Conductive layer 311 serves as a gate electrode. Insulating layer 313 is located between substrate 301 and conductive layer 311 and serves as a gate insulating layer. Low-resistance region 312 is a region in substrate 301 doped with impurities and serves as one of the source and drain electrodes. Insulating layer 314 covers the sidewalls of conductive layer 311.

[0336] In addition, a component separation layer 315 is provided between two adjacent transistors 310 in such a way as to be embedded in the substrate 301.

[0337] In addition, an insulating layer 261 is provided in such a way as to cover the transistor 310, and a capacitor 240 is provided on the insulating layer 261.

[0338] The capacitor 240 includes a conductive layer 241, a conductive layer 245, and an insulating layer 243 located therebetween. The conductive layer 241 serves as one electrode of the capacitor 240, the conductive layer 245 serves as the other electrode of the capacitor 240, and the insulating layer 243 serves as the dielectric of the capacitor 240.

[0339] A conductive layer 241 is disposed on an insulating layer 261 and embedded in an insulating layer 254. The conductive layer 241 is electrically connected to one of the source and drain electrodes of a transistor 310 via a plug 271 embedded in the insulating layer 261. An insulating layer 243 is disposed covering the conductive layer 241. A conductive layer 245 is disposed in the region where it overlaps with the conductive layer 241, separated by the insulating layer 243.

[0340] An insulating layer 255 is provided to cover the capacitor 240, and light-emitting elements 430a, 430b, 430c, etc. are provided on the insulating layer 255. A protective layer 415 is provided on the light-emitting elements 430a, 430b, 430c, and a substrate 420 is attached to the top surface of the protective layer 415 through a resin layer 419. The substrate 420 corresponds to the substrate 292 in FIG. 14A. The protective layer 415 corresponds to the protective layer 121 in Embodiment 1, etc.

[0341] The pixel electrode of the light-emitting element is electrically connected to one of the source and drain of the transistor 310 via a plug 256 embedded in the insulating layer 255, a conductive layer 241 embedded in the insulating layer 254, and a plug 271 embedded in the insulating layer 261.

[0342] [Display Device 400D] The main difference between the display device 400D shown in Figure 16 and the display device 400C is the structure of the transistor. Note that descriptions of parts that are the same as those in the display device 400C are sometimes omitted.

[0343] Transistor 320 is a transistor that uses metal oxide (also known as oxide semiconductor) in the semiconductor layer that forms the channel.

[0344] Transistor 320 includes semiconductor layer 321, insulating layer 323, conductive layer 324, a pair of conductive layers 325, insulating layer 326 and conductive layer 327.

[0345] Substrate 331 is equivalent to substrate 291 in FIG14A and FIG14B. Insulating substrate or semiconductor substrate can be used as substrate 331.

[0346] An insulating layer 332 is provided on the substrate 331. The insulating layer 332 serves as a barrier layer, which prevents impurities such as water or hydrogen from diffusing from the substrate 331 to the transistor 320 and prevents oxygen from escaping from the semiconductor layer 321 to the insulating layer 332 side. As the insulating layer 332, for example, a film that is less susceptible to hydrogen or oxygen diffusion than a silicon oxide film, such as an aluminum oxide film, a hafnium oxide film, or a silicon nitride film, can be used.

[0347] A conductive layer 327 is provided on the insulating layer 332, and an insulating layer 326 is provided to cover the conductive layer 327. The conductive layer 327 serves as the first gate electrode of the transistor 320, and a portion of the insulating layer 326 serves as the first gate insulating layer. Preferably, the portion of the insulating layer 326 that contacts the semiconductor layer 321 is an oxide insulating film such as silicon oxide. Preferably, the top surface of the insulating layer 326 is planarized.

[0348] A semiconductor layer 321 is disposed on an insulating layer 326. Preferably, the semiconductor layer 321 contains a metal oxide (also known as an oxide semiconductor) film with semiconductor properties. Materials suitable for the semiconductor layer 321 will be described in detail later.

[0349] A pair of conductive layers 325 are in contact with the semiconductor layer 321 and serve as the source electrode and the drain electrode.

[0350] In addition, an insulating layer 328 is provided to cover the top and side surfaces of the pair of conductive layers 325 and the side surfaces of the semiconductor layer 321, and an insulating layer 264 is provided on the insulating layer 328. The insulating layer 328 serves as a barrier layer, which prevents impurities such as water or hydrogen from diffusing from the insulating layer 264 to the semiconductor layer 321 and oxygen from detaching from the semiconductor layer 321. As the insulating layer 328, the same insulating film as the insulating layer 332 described above can be used.

[0351] Openings are provided in insulating layer 328 and insulating layer 264 to reach semiconductor layer 321. An insulating layer 323 and a conductive layer 324 are embedded inside the openings, contacting the sides of insulating layer 264, insulating layer 328, and conductive layer 325, as well as the top surface of semiconductor layer 321. Conductive layer 324 is used as a second gate electrode, and insulating layer 323 is used as a second gate insulating layer.

[0352] The top surfaces of the conductive layer 324, the insulating layer 323, and the insulating layer 264 are flattened so that their heights are approximately the same, and insulating layers 329 and 265 are provided to cover them.

[0353] Insulating layers 264 and 265 are used as interlayer insulating layers. Insulating layer 329 is used as a barrier layer to prevent impurities such as water or hydrogen from diffusing from insulating layer 265 to transistor 320. Insulating layer 329 may use the same insulating film as insulating layers 328 and 332 described above.

[0354] A plug 274, electrically connected to one of the pair of conductive layers 325, is embedded in insulating layers 265, 329, and 264. Preferably, the plug 274 is a conductive layer 274a having a portion of the top surface of the conductive layer 325 covering the side surfaces of the openings of each of the insulating layers 265, 329, 264, and 328, and a conductive layer 274b in contact with the top surface of the conductive layer 274a. Preferably, the conductive layer 274a is made of a conductive material that does not readily diffuse hydrogen and oxygen.

[0355] The structure from the insulating layer 254 to the substrate 420 in the display device 400D is the same as that in the display device 400C.

[0356] [Display Device 400E] The display device 400E shown in FIG17 has a structure in which transistors 310A and 310B are stacked with channels respectively formed in a semiconductor substrate.

[0357] The display device 400E has a structure in which a substrate 301B, on which a transistor 310B, a capacitor 240 and each light-emitting device are disposed, is bonded to a substrate 301A on which a transistor 310A is disposed.

[0358] The substrate 301B is provided with a plug 343 that penetrates the substrate 301B. In addition, the plug 343 is electrically connected to a conductive layer 342 provided on the back side of the substrate 301B (the surface opposite to the side of the substrate 420). On the other hand, the substrate 301A is provided with a conductive layer 341 on the insulating layer 261.

[0359] By bonding conductive layer 341 and conductive layer 342, substrate 301A and substrate 301B are electrically connected.

[0360] It is preferable that the same conductive material is used for both conductive layers 341 and 342. For example, a metal film containing elements selected from Al, Cr, Cu, Ta, Ti, Mo, and W, or a metal nitride film (titanium nitride film, molybdenum nitride film, tungsten nitride film) composed of the aforementioned elements can be used. In particular, copper is preferably used for both conductive layers 341 and 342. This allows for the use of Cu-Cu (copper-copper) direct bonding technology (a technique that forms electrical conductivity by connecting Cu (copper) pads). Alternatively, conductive layers 341 and 342 can be bonded using bumps.

[0361] [Display Device 400F] In the display device 400F shown in FIG18, a transistor 310 having a channel formed on a substrate 301 and a transistor 320 having a metal oxide semiconductor layer forming the channel are stacked. Note that the description of the same parts as those in display devices 400C, 400D, and 400E is sometimes omitted.

[0362] An insulating layer 261 is provided to cover the transistor 310, and a conductive layer 251 is provided on the insulating layer 261. Furthermore, an insulating layer 262 is provided to cover the conductive layer 251, and a conductive layer 252 is provided on the insulating layer 262. Both the conductive layer 251 and the conductive layer 252 are used for wiring. Furthermore, insulating layers 263 and 332 are provided to cover the conductive layer 252, and a transistor 320 is provided on the insulating layer 332. Furthermore, an insulating layer 265 is provided to cover the transistor 320, and a capacitor 240 is provided on the insulating layer 265. The capacitor 240 and the transistor 320 are electrically connected via a connector 274.

[0363] Transistor 320 can be used as a transistor constituting a pixel circuit. Furthermore, transistor 310 can be used as a transistor constituting a pixel circuit or as a transistor constituting a drive circuit (gate line drive circuit, source line drive circuit) used to drive the pixel circuit. Moreover, transistors 310 and 320 can be used as transistors constituting various circuits such as arithmetic circuits or memory circuits.

[0364] With this structure, not only pixel circuits but also driving circuits can be formed directly under the light-emitting element. Therefore, compared with the case where driving circuits are set around the display area, the display device can be miniaturized.

[0365] At least a portion of the structural examples shown in this embodiment and the corresponding diagrams can be appropriately combined with other structural examples or diagrams.

[0366] Embodiment 4 In this embodiment, a light-emitting element (also called a light-emitting device) of a display device that can be used in one embodiment of the present invention will be described.

[0367] <Structural Example of a Light-Emitting Element> As shown in Figure 19A, the light-emitting element includes an EL layer 786 between a pair of electrodes (lower electrode 772 and upper electrode 788). The EL layer 786 may be composed of multiple layers such as layer 4420, light-emitting layer 4411, and layer 4430. Layer 4420 may include, for example, a layer containing a substance with high electron injection capability (electron injection layer) and a layer containing a substance with high electron transport capability (electron transport layer). Light-emitting layer 4411 may, for example, contain a luminescent compound. Layer 4430 may, for example, include a layer containing a substance with high hole injection capability (hole injection layer) and a layer containing a substance with high hole transport capability (hole transport layer).

[0368] The structure including layer 4420, light-emitting layer 4411 and layer 4430 disposed between a pair of electrodes can be used as a single light-emitting unit. In this specification, the structure of FIG19A is referred to as a single structure.

[0369] Additionally, FIG19B shows a modified example of the EL layer 786 included in the light-emitting element shown in FIG19A. Specifically, the light-emitting element shown in FIG19B includes layer 4430-1 on the lower electrode 772, layer 4430-2 on layer 4430-1, light-emitting layer 4411 on layer 4430-2, layer 4420-1 on light-emitting layer 4411, layer 4420-2 on layer 4420-1, and upper electrode 788 on layer 4420-2. For example, when the lower electrode 772 is used as the anode and the upper electrode 788 is used as the cathode, layer 4430-1 is used as the hole injection layer, layer 4430-2 is used as the hole transport layer, layer 4420-1 is used as the electron transport layer, and layer 4420-2 is used as the electron injection layer. Alternatively, when the lower electrode 772 is used as the cathode and the upper electrode 788 is used as the anode, layer 4430-1 is used as an electron injection layer, layer 4430-2 as an electron transport layer, layer 4420-1 as a hole transport layer, and layer 4420-2 as a hole injection layer. By employing the above layer structure, carriers can be efficiently injected into the light-emitting layer 4411, thereby improving the recombination efficiency of carriers within the light-emitting layer 4411.

[0370] In addition, as shown in Figures 19C and 19D, the structure in which multiple light-emitting layers (light-emitting layers 4411, 4412, and 4413) are disposed between layer 4420 and layer 4430 is also a variant example of a single structure.

[0371] As shown in Figures 19E and 19F, the structure in which multiple light-emitting units (EL layers 786a and 786b) are connected in series with an intermediate layer (charge generation layer) 4440 is referred to as a series structure in this specification. While the structure shown in Figures 19E and 19F is referred to as a series structure in this specification, it is not limited thereto; for example, a series structure may also be referred to as a stacked structure. By employing a series structure, a light-emitting element capable of emitting light with high brightness can be realized.

[0372] In Figure 19C, light-emitting materials that emit light of the same color can also be used for light-emitting layers 4411, 4412 and 4413.

[0373] Alternatively, different luminescent materials can be used for luminescent layers 4411, 4412, and 4413. When the light emitted by each of luminescent layer 4411, 4412, and 4413 is in a complementary color relationship, white light emission can be obtained. Figure 19D shows an example of a color layer 785 used as a color filter. By allowing white light to pass through the color filter, light of the desired color can be obtained.

[0374] Alternatively, in FIG19E, the same luminescent material can be used for luminescent layers 4411 and 4412. Alternatively, luminescent materials emitting different colors of light can be used for luminescent layers 4411 and 4412. When the light emitted by luminescent layer 4411 and the light emitted by luminescent layer 4412 are complementary colors, white light emission can be obtained. FIG19F shows an example where a color layer 785 is also provided.

[0375] In addition, by combining the structure shown in FIG19D or FIG19F, which involves setting a color filter on an element capable of emitting white light, with the MML structure of one embodiment of the present invention, a display device with high contrast can be realized.

[0376] In addition, in Figures 19C, 19D, 19E and 19F, layers 4420 and 4430 may also have a stacked structure of two or more layers as shown in Figure 19B.

[0377] Sometimes, a structure in which an EL layer corresponding to the emitted color (here, blue (B), green (G), and red (R)) is formed separately for each light-emitting device is called an SBS (Side By Side) structure. Note that in an SBS structure, EL layers that can emit white light can also be formed separately for each light-emitting device in a single-structure or series structure. When an SBS structure is used for a light-emitting device that can emit white light, the layers disposed between the light-emitting devices (e.g., organic layers shared between the light-emitting devices, also called common layers) are separated, thereby enabling displays with no or very little side leakage.

[0378] The emission color of the light-emitting element can be red, green, blue, cyan, magenta, yellow, or white, depending on the material constituting the EL layer 786. Furthermore, when the light-emitting element has a microcavity structure, the color purity can be further improved.

[0379] A white light-emitting device preferably has a structure in which the light-emitting layer contains two or more light-emitting materials. When white light emission is obtained using two light-emitting materials, the light-emitting materials can be selected in such a way that the light emission of each of the two or more light-emitting materials is in a complementary color relationship. For example, by making the light emission color of the first light-emitting layer and the light emission color of the second light-emitting layer in a complementary color relationship, a light-emitting device that emits white light as a whole can be obtained. Furthermore, in the case of a light-emitting device that includes three or more light-emitting materials, a structure in which the light emission color of each of the three or more light-emitting materials is mixed together, resulting in white light emission as a whole, can be adopted.

[0380] Furthermore, the luminescent layer preferably comprises two or more luminescent materials that each emits light in the form of R (red), G (green), B (blue), Y (yellow), O (orange), etc. Alternatively, it is preferably comprised of two or more luminescent materials that each emits light in the form of two or more spectral components of R, G, and B.

[0381] Here, a specific structural example of a light-emitting element is described.

[0382] The light-emitting element includes at least a light-emitting layer. In addition, as a layer other than the light-emitting layer, the light-emitting element may also include a layer containing a material with high hole injection capacity, a material with high hole transport capacity, a hole blocking material, a material with high electron transport capacity, an electron blocking material, a material with high electron injection capacity, or a bipolar material (a material with high electron transport capacity and high hole transport capacity).

[0383] Light-emitting devices can use low-molecular-weight compounds or high-molecular-weight compounds, and may also contain inorganic compounds. The layers constituting the light-emitting device can be formed by methods such as vapor deposition (including vacuum vapor deposition), transfer printing, printing, inkjet printing, and coating.

[0384] For example, the light-emitting device may include one or more of a hole injection layer, a hole transport layer, a hole barrier layer, an electron barrier layer, an electron transport layer, and an electron injection layer.

[0385] The hole injection layer is a layer that injects holes from the anode into the hole transport layer, and it is a layer containing a material with high hole injection capability. As a material with high hole injection capability, aromatic amine compounds, composite materials containing hole transport materials and acceptor materials (electron acceptor materials), etc. can be used.

[0386] The hole transport layer is a layer that transports holes injected from the anode through the hole injection layer to the light-emitting layer. The hole transport layer is a layer containing a hole-transporting material. As a hole-transporting material, it is preferable to use a material with a hole mobility of 1×10-6 cm² / Vs or higher. In addition, any material other than the above can be used as long as its hole transportability is higher than its electron transportability. As a hole transporting material, it is preferable to use materials with high hole transportability such as π-electron-rich heteroaromatic compounds (e.g., carbazole derivatives, thiophene derivatives, furan derivatives, etc.) or aromatic amines (compounds containing an aromatic amine skeleton).

[0387] The electron transport layer is a layer that transports electrons injected from the cathode by the electron injection layer to the light-emitting layer. The electron transport layer is a layer containing an electron transport material. As an electron transport material, it is preferable to use a material with an electron mobility of 1×10-6 cm2 / Vs or higher. In addition, any material other than the above can be used as long as its electron transportability is higher than its hole transportability. As an electron transport material, metal complexes with a quinoline skeleton, metal complexes with a benzoquinoline skeleton, metal complexes with a chloroazole skeleton, metal complexes with a thiazole skeleton, etc., can also be used. Materials with high electron transportability, such as chlorodiazole derivatives, triazole derivatives, imidazole derivatives, chloroazole derivatives, thiazole derivatives, phenobarbital derivatives, quinoline derivatives with quinoline ligands, benzoquinoline derivatives, quinoline derivatives, dibenzoquinoline derivatives, pyridine derivatives, bipyridine derivatives, pyrimidine derivatives, nitrogen-containing heteroaromatic compounds, and other π-electron-deficient heteroaromatic compounds, can also be used.

[0388] The electron injection layer is a layer containing a material with high electron injection capability, through which electrons are injected from the cathode into the electron transport layer. As a material with high electron injection capability, alkali metals, alkaline earth metals, or compounds containing the above substances can be used. As a material with high electron injection capability, a composite material containing an electron transport material and a donor material (electron donor material) can also be used.

[0389] As the electron injection layer, for example, lithium, cesium, lithium fluoride (LiF), cesium fluoride (CsF), calcium fluoride (CaF2), 8-(hydroxyoxoline) lithium (abbreviated as: Liq), 2-(2-pyridyl)phenol lithium (abbreviated as: LiPP), 2-(2-pyridyl)-3-hydroxypyridinolato lithium (abbreviated as: LiPPy), 4-phenyl-2-(2-pyridyl)phenol lithium (abbreviated as: LiPPP), lithium oxide (LiOx), cesium carbonate, and other alkali metals, alkaline earth metals, or compounds thereof can be used.

[0390] Furthermore, materials with electron transport properties can also be used as the aforementioned electron injection layer. For example, compounds having non-shared electron pairs and electron-deficient heteroaromatic rings can be used as materials with electron transport properties. Specifically, compounds containing at least one of pyridine rings, diazine rings (pyrimidine rings, pyrazine rings, pyrazine rings), and triazine rings can be used.

[0391] The lowest unoccupied molecular orbital (LUMO) of organic compounds with non-shared electron pairs is preferably above -3.6 eV and below -2.3 eV. Furthermore, generally, cyclic voltammetry (CV), photoelectron spectroscopy, optical absorption spectroscopy, and inverse photoelectron spectroscopy are used to estimate the highest occupied molecular orbital (HOMO) and LUMO levels of organic compounds.

[0392] For example, 4,7-diphenyl-1,10-phenanthroline (abbreviated as BPhen), 2,9-di(naphthyl-2-yl)-4,7-diphenyl-1,10-phenanthroline (abbreviated as NBPhen), diquinoline[2,3-a:2',3'-c]phenazine (abbreviated as HATNA), and 2,4,6-tris[3'-(pyridin-3-yl)biphenyl-3-yl]-1,3,5-triazine (abbreviated as TmPPPyTz) can be used in organic compounds with non-shared electron pairs. Furthermore, compared to BPhen, NBPhen has a higher glass transition temperature (Tg) and better heat resistance.

[0393] The luminescent layer is a layer containing a luminescent substance. The luminescent layer may contain one or more luminescent substances. In addition, substances that emit light in colors such as blue, purple, blue-violet, green, yellow-green, yellow, orange, and red are appropriately used as luminescent substances. Furthermore, substances that emit near-infrared light may also be used as luminescent substances.

[0394] As luminescent materials, examples include fluorescent materials, phosphorescent materials, TADF materials, quantum dot materials, etc.

[0395] As fluorescent materials, examples include pyrene derivatives, anthracene derivatives, triphenylene derivatives, fumonisin derivatives, carbazole derivatives, dibenzothiophene derivatives, dibenzofuran derivatives, dibenzoquinoline derivatives, quinoline derivatives, pyridine derivatives, pyrimidine derivatives, phenanthrene derivatives, naphthalene derivatives, etc.

[0396] As phosphorescent materials, examples include organometallic complexes (especially iridium complexes) having a 4H-triazole skeleton, a 1H-triazole skeleton, an imidazole skeleton, a pyrimidine skeleton, a pyrazine skeleton or a pyridine skeleton, organometallic complexes (especially iridium complexes) with phenylpyridine derivatives having electron-withdrawing groups as ligands, platinum complexes, rare earth metal complexes, etc.

[0397] In addition to the luminescent material (guest material), the luminescent layer may also contain one or more organic compounds (host material, auxiliary material, etc.). As one or more organic compounds, one or both of hole transport materials and electron transport materials may be used. Furthermore, as one or more organic compounds, bipolar materials or TADF materials may also be used.

[0398] For example, the light-emitting layer is preferably a combination of a phosphorescent material, a hole transport material that readily forms excited-state complexes, and an electron transport material. By employing such a structure, ExTET (Exciplex-Triplet Energy Transfer) luminescence, utilizing energy transfer from the excited-state complex to the luminescent material (phosphorescent material), can be efficiently obtained. By selecting a combination of excited-state complexes that form light whose wavelength overlaps with the absorption band on the lowest energy side of the luminescent material, energy transfer can be facilitated, thereby achieving efficient luminescence. This structure enables the simultaneous realization of high efficiency, low-voltage operation, and long lifetime of the light-emitting device.

[0399] This embodiment can be appropriately combined with other embodiments.

[0400] Embodiment 5 In this embodiment, a metal oxide (also called an oxide semiconductor) that can be used in the OS transistor described in the above embodiments is explained.

[0401] The metal oxide preferably contains at least indium or zinc. It is particularly preferred to contain both indium and zinc. In addition, it is preferred to also contain aluminum, gallium, yttrium or tin. Furthermore, it may also contain one or more of the following: boron, silicon, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, magnesium and cobalt.

[0402] In addition, metal oxides can be formed by sputtering, MOCVD or other CVD methods or ALD methods.

[0403] <Classification of Crystal Structures> As for the crystal structures of oxide semiconductors, examples include amorphous (including completely amorphous), CAAC (c-axis-aligned crystalline), nc (nanocrystalline), CAC (cloud-aligned composite), single crystal, and polycrystalline.

[0404] The crystal structure of a film or substrate can be evaluated using X-ray diffraction (XRD) spectroscopy. For example, the XRD spectrum obtained can be evaluated using GIXD (Grazing-Incidence XRD). Furthermore, the GIXD method is also known as the thin film method or the Seemann-Bohlin method.

[0405] For example, the peak shapes of the XRD spectrum of a quartz glass substrate are generally symmetrical. On the other hand, the peak shapes of the XRD spectrum of an IGZO film with a crystalline structure are not symmetrical. The asymmetry of the XRD peak shapes indicates the presence of crystals in the film or substrate. In other words, unless the XRD peak shapes are symmetrical, it cannot be said that the film or substrate is in an amorphous state.

[0406] Furthermore, the crystal structure of the film or substrate can be evaluated using diffraction patterns observed by nano-beam electron diffraction (NBED). For example, the observation of a halo pattern in the diffraction pattern of a quartz glass substrate confirms that the quartz glass is in an amorphous state. In contrast, a spot-like pattern without a halo was observed in the diffraction pattern of an IGZO film deposited at room temperature. Therefore, it can be inferred that the IGZO film deposited at room temperature is in an intermediate state that is neither crystalline nor amorphous, and it cannot be concluded that the IGZO film is amorphous.

[0407] <<Structure of Oxide Semiconductors>> Furthermore, when focusing on the structure of oxide semiconductors, the classification of oxide semiconductors sometimes differs from the classifications described above. For example, oxide semiconductors can be classified into single-crystal oxide semiconductors and other non-single-crystal oxide semiconductors. Examples of non-single-crystal oxide semiconductors include, for example, the aforementioned CAAC-OS and nc-OS. Furthermore, non-single-crystal oxide semiconductors include polycrystalline oxide semiconductors, a-like OS (amorphous-like oxide semiconductor), and amorphous oxide semiconductors, etc.

[0408] Here, the details of CAAC-OS, nc-OS and a-like OS are explained.

[0409] [CAAC-OS] CAAC-OS is an oxide semiconductor comprising multiple crystalline regions whose c-axis is aligned in a specific direction. Furthermore, the specific direction refers to the thickness direction of the CAAC-OS film, the normal direction of the formed surface of the CAAC-OS film, or the normal direction of the surface of the CAAC-OS film. Additionally, the crystalline region is a region with a periodic atomic arrangement. Note that when the atomic arrangement is considered as a lattice arrangement, the crystalline region is also a region with a consistent lattice arrangement. Moreover, CAAC-OS has a region where multiple crystalline regions are connected in the ab-plane direction, and sometimes this region exhibits distortion. Furthermore, distortion refers to the portion of the lattice arrangement direction that changes between regions with consistent lattice arrangement and other regions with consistent lattice arrangement in the region where multiple crystalline regions are connected. In other words, CAAC-OS refers to an oxide semiconductor with c-axis alignment but no obvious alignment in the ab-plane direction.

[0410] Furthermore, each of the aforementioned multiple crystalline regions is composed of one or more microcrystals (crystals with a maximum diameter of less than 10 nm). When a crystalline region is composed of a single microcrystal, the maximum diameter of that crystalline region is less than 10 nm. Furthermore, when a crystalline region is composed of multiple microcrystals, the size of that crystalline region is sometimes around tens of nm.

[0411] Furthermore, in In-M-Zn oxides (where element M is selected from one or more of aluminum, gallium, yttrium, tin, and titanium), CAAC-OS tends to have a layered crystal structure (also called a layered structure) consisting of layers containing indium (In) and oxygen (hereinafter, In layer) and layers containing element M, zinc (Zn), and oxygen (hereinafter, (M, Zn) layer). In addition, indium and element M can substitute for each other. Therefore, sometimes the (M, Zn) layer contains indium. Furthermore, sometimes the In layer contains element M. Note that sometimes the In layer contains Zn. This layered structure is observed, for example, as a lattice image in high-resolution TEM (Transmission Electron Microscope) images.

[0412] For example, when performing structural analysis on a CAAC-OS film using an XRD apparatus, a peak representing c-axis alignment is detected at or near 2θ = 31° in out-of-plane XRD measurements using θ / 2θ scanning. Note that the position (2θ value) of the peak representing c-axis alignment sometimes varies depending on the type and composition of the metal elements constituting CAAC-OS.

[0413] Furthermore, for example, multiple bright spots (spots) were observed in the electron diffraction pattern of the CAAC-OS film. In addition, when the spot of the incident electron beam passing through the sample (also known as the direct spot) is taken as the center of symmetry, one spot and other spots are observed at point-symmetric positions.

[0414] When observing the crystalline region from the aforementioned specific direction, although the lattice arrangement in the crystalline region is basically hexagonal, the unit lattice is not limited to a regular hexagon; there are cases where it is non-regular hexagonal. Furthermore, in the aforementioned distortions, pentagonal, heptagonal, and other lattice arrangements are sometimes present. Moreover, no clear grain boundary is observed near the distortion of CAAC-OS. That is, the distortion of the lattice arrangement inhibits the formation of grain boundaries. This may be because CAAC-OS can accommodate distortion due to the low density of oxygen atoms in the ab-plane direction and the change in interatomic bonding distance caused by the substitution of metal atoms.

[0415] Furthermore, a crystalline structure with clearly defined grain boundaries is called a polycrystalline structure. Grain boundaries become recombination centers where carriers are trapped, potentially leading to a decrease in the transistor's on-state current and field-effect mobility. Therefore, CAAC-OS, where clearly defined grain boundaries are not identified, is one of the crystalline oxides that provides an excellent crystalline structure for the semiconductor layer of the transistor. Note that a structure containing Zn is preferred for constructing CAAC-OS. For example, In-Zn oxides and In-Ga-Zn oxides are preferred because they can further suppress grain boundary formation compared to In oxides.

[0416] CAAC-OS is an oxide semiconductor with high crystallinity and no clearly defined grain boundaries. Therefore, it can be said that in CAAC-OS, the decrease in electron mobility due to grain boundaries is less likely to occur. Furthermore, the crystallinity of oxide semiconductors can sometimes decrease due to the incorporation of impurities or the formation of defects; therefore, CAAC-OS can be considered an oxide semiconductor with few impurities and defects (such as oxygen vacancies). Therefore, oxide semiconductors containing CAAC-OS have stable physical properties. Thus, oxide semiconductors containing CAAC-OS exhibit high heat resistance and high reliability. In addition, CAAC-OS is also stable against high temperatures (so-called thermal budget) in the manufacturing process. Therefore, by using CAAC-OS in OS transistors, process flexibility can be increased.

[0417] [nc-OS] In nc-OS, the atomic arrangement in tiny regions (e.g., regions larger than 1 nm and smaller than 10 nm, particularly regions larger than 1 nm and smaller than 3 nm) exhibits periodicity. In other words, nc-OS possesses tiny crystals. Furthermore, for example, these tiny crystals are sized between 1 nm and 10 nm, particularly between 1 nm and 3 nm, and are referred to as nanocrystals. Moreover, no regularity in crystal orientation is observed between different nanocrystals in nc-OS. Therefore, no alignment is observed in the overall film. Thus, sometimes nc-OS is indistinguishable from a-like OS or amorphous oxide semiconductors in certain analytical methods. For example, when performing structural analysis on nc-OS films using an XRD apparatus, no peaks indicating crystallinity are detected in out-of-plane XRD measurements using θ / 2θ scanning. Furthermore, when performing electron diffraction (also known as selected area electron diffraction) on nc-OS films using an electron beam with a beam diameter larger than that of nanocrystals (e.g., larger than 50 nm), a diffraction pattern resembling a halo pattern is observed. On the other hand, when electron diffraction (also known as nano-beam electron diffraction) is performed on nc-OS films using an electron beam whose beam diameter is close to or smaller than the size of nanocrystals (e.g., above 1 nm and below 30 nm), electron diffraction patterns of multiple spots are sometimes observed in an annular region centered on a direct spot.

[0418] [a-like OS] a-like OS is an oxide semiconductor with a structure intermediate between nc-OS and amorphous oxide semiconductors. a-like OS contains voids or low-density regions. That is, the crystallinity of a-like OS is lower than that of nc-OS and CAAC-OS. In addition, the hydrogen concentration in the film of a-like OS is higher than that in the films of nc-OS and CAAC-OS.

[0419] <<Structure of Oxide Semiconductors>> Next, the details of the above-mentioned CAC-OS will be explained. In addition, CAC-OS is related to the material composition.

[0420] [CAC-OS] CAC-OS refers, for example, to a composition in which elements contained in a metal oxide are unevenly distributed, wherein the size of the material containing the unevenly distributed elements is 0.5 nm or more and 10 nm or less, preferably 1 nm or more and 3 nm or approximately. Note that, below, the state in which one or more metal elements are unevenly distributed in a metal oxide and the regions containing those metal elements are mixed is also referred to as mosaic or patch-like, wherein the size of the region is 0.5 nm or more and 10 nm or less, preferably 1 nm or more and 3 nm or approximately.

[0421] Furthermore, CAC-OS refers to a structure in which the material is separated into a first region and a second region, forming a mosaic-like structure, and the first region is distributed in the film (hereinafter also referred to as cloud-like). That is to say, CAC-OS refers to a composite metal oxide having a structure in which the first region and the second region are mixed.

[0422] Here, each of the atomic ratios of In, Ga, and Zn relative to the metal elements constituting the CAC-OS of the In-Ga-Zn oxide is denoted as [In], [Ga], and [Zn]. For example, in the CAC-OS of the In-Ga-Zn oxide, a first region is a region where [In] is greater than [In] in the composition of the CAC-OS film. Furthermore, a second region is a region where [Ga] is greater than [Ga] in the composition of the CAC-OS film. Additionally, for example, a first region is a region where [In] is greater than [In] in the second region and [Ga] is less than [Ga] in the second region. Furthermore, a second region is a region where [Ga] is greater than [Ga] in the first region and [In] is less than [In] in the first region.

[0423] Specifically, the first region described above is a region whose main component is indium oxide or indium zinc oxide. Furthermore, the second region described above is a region whose main component is gallium oxide or gallium zinc oxide. In other words, the first region described above can be referred to as a region whose main component is In. Furthermore, the second region described above can be referred to as a region whose main component is Ga.

[0424] Note that sometimes the clear boundary between the first region and the second region mentioned above cannot be observed.

[0425] Furthermore, CAC-OS in In-Ga-Zn oxides refers to the following composition: in a material composition containing In, Ga, Zn, and O, regions with Ga as the main component and regions with In as the main component exist irregularly in a mosaic pattern. Therefore, it can be inferred that CAC-OS has a structure with uneven distribution of metal elements.

[0426] CAC-OS can be formed, for example, by sputtering without heating the substrate. When forming CAC-OS by sputtering, one or more gases selected from inert gases (typically argon), oxygen gases, and nitrogen gases can be used as the deposition gas. Furthermore, the lower the oxygen gas flow rate in the total flow rate of the deposition gas during deposition, the better; for example, it is preferable that the oxygen gas flow rate in the total flow rate of the deposition gas during deposition is 0% or more and less than 30%, more preferably 0% or more and less than 10%.

[0427] For example, in the CAC-OS of In-Ga-Zn oxide, based on the EDX-mapping image obtained by Energy Dispersive X-ray spectroscopy (EDX), a structure with a non-uniformly distributed and mixed region of In-dominant components (first region) and Ga-dominant components (second region) can be identified.

[0428] Here, the first region is a region with higher conductivity than the second region. That is, when carriers flow through the first region, it exhibits conductivity as a metal oxide. Therefore, when the first region is distributed in a cloud-like manner in the metal oxide, a high field mobility (μ) can be achieved.

[0429] On the other hand, the second region is a region with higher insulation than the first region. That is, when the second region is distributed in the metal oxide, leakage current can be suppressed.

[0430] Therefore, when CAC-OS is used in a transistor, the complementary effect of conductivity arising from the first region and insulation arising from the second region enables CAC-OS to have a switching function (the function of controlling on / off). In other words, CAC-OS has a conductive function in one part of the material and an insulating function in another part, and a semiconductor function in the material as a whole. By separating the conductive and insulating functions, each function can be maximized. Therefore, by using CAC-OS in a transistor, a large on-state current (Ion), high field-effect mobility (μ), and good switching operation can be achieved.

[0431] Furthermore, transistors using CAC-OS have high reliability. Therefore, CAC-OS is best suited for various semiconductor devices such as display devices.

[0432] Oxide semiconductors have various structures and properties. In one embodiment of the present invention, the oxide semiconductor may also include two or more of amorphous oxide semiconductors, polycrystalline oxide semiconductors, a-like OS, CAC-OS, nc-OS, and CAAC-OS.

[0433] <Transistor with oxide semiconductor> Next, we will explain the case of using the above-mentioned oxide semiconductor as a transistor.

[0434] By using the above-mentioned oxide semiconductor in transistors, transistors with high field-effect mobility can be realized. In addition, transistors with high reliability can be realized.

[0435] Preferably, an oxide semiconductor with a low carrier concentration is used in the transistor. For example, the carrier concentration in the oxide semiconductor is 1×10¹⁷ cm⁻³ or less, preferably 1×10¹⁵ cm⁻³ or less, more preferably 1×10¹³ cm⁻³ or less, further preferably 1×10¹¹ cm⁻³ or less, and even more preferably less than 1×10¹⁰ cm⁻³ and more than 1×10⁻⁹ cm⁻³. When the purpose is to reduce the carrier concentration of the oxide semiconductor film, the impurity concentration in the oxide semiconductor film can be reduced to reduce the defect state density. In this specification, the state of low impurity concentration and low defect state density is referred to as high purity or substantially high purity. In addition, sometimes an oxide semiconductor with a low carrier concentration is referred to as a high purity or substantially high purity oxide semiconductor.

[0436] Because oxide semiconductor films of high purity or essentially high purity have a low defect state density, they may have a low trap state density.

[0437] Furthermore, the charge trapped in the trap state of the oxide semiconductor takes a long time to disappear, and sometimes it acts like a fixed charge. Therefore, the electrical properties of the transistor that forms the channel formation region in the oxide semiconductor with a high trap state density are sometimes unstable.

[0438] Therefore, in order to stabilize the electrical properties of the transistor, it is effective to reduce the impurity concentration in the oxide semiconductor. To further reduce the impurity concentration in the oxide semiconductor, it is preferable to also reduce the impurity concentration in the adjacent film. Examples of impurities include hydrogen, nitrogen, alkali metals, alkaline earth metals, iron, nickel, and silicon.

[0439] <Impurities> Here, we explain the effects of various impurities in oxide semiconductors.

[0440] When the oxide semiconductor contains silicon or carbon, one of the elements in Group 14, defect states are formed in the oxide semiconductor. Therefore, the concentration of silicon or carbon in the oxide semiconductor or near the interface with the oxide semiconductor (the concentration measured by secondary ion mass spectrometry (SIMS)) is set to 2 × 10¹⁸ atoms / cm³ or less, preferably 2 × 10¹⁷ atoms / cm³ or less.

[0441] Furthermore, when an oxide semiconductor contains an alkali metal or an alkaline earth metal, defect states are sometimes formed, thus creating carriers. Therefore, transistors using oxide semiconductors containing alkali metals or alkaline earth metals tend to have always-on characteristics. Therefore, the concentration of alkali metals or alkaline earth metals in the oxide semiconductor, as measured by SIMS, is preferably 1 × 10¹⁸ atoms / cm³ or less, and more preferably 2 × 10¹⁶ atoms / cm³ or less.

[0442] When an oxide semiconductor contains nitrogen, electrons are easily generated as carriers, increasing the carrier concentration and resulting in n-type characteristics. As a result, transistors using nitrogen-containing oxide semiconductors tend to have always-on characteristics. Alternatively, when an oxide semiconductor contains nitrogen, trapped states may sometimes form. Consequently, the electrical properties of the transistor may sometimes be unstable. Therefore, the nitrogen concentration in the oxide semiconductor, as measured by SIMS, is set to be below 5 × 10¹⁹ atoms / cm³, preferably below 5 × 10¹⁸ atoms / cm³, more preferably below 1 × 10¹⁸ atoms / cm³, and even more preferably below 5 × 10¹⁷ atoms / cm³.

[0443] Hydrogen contained in an oxide semiconductor reacts with oxygen bonded to a metal atom to form water, thus sometimes creating oxygen vacancies. When hydrogen enters this oxygen vacancy, electrons as carriers are sometimes generated. Furthermore, sometimes a portion of the hydrogen bonds with oxygen bonded to a metal atom, generating electrons as carriers. Therefore, transistors using oxide semiconductors containing hydrogen tend to have always-on characteristics. Thus, it is preferable to minimize the amount of hydrogen in the oxide semiconductor. Specifically, in the oxide semiconductor, the hydrogen concentration measured using SIMS is set to be less than 1 × 10²⁰ atoms / cm³, preferably less than 1 × 10¹⁹ atoms / cm³, more preferably less than 5 × 10¹⁸ atoms / cm³, and even more preferably less than 1 × 10¹⁸ atoms / cm³.

[0444] By using oxide semiconductors with sufficiently reduced impurities in the channel formation region of the transistor, the transistor can have stable electrical characteristics.

[0445] At least a portion of this embodiment may be implemented in combination with other embodiments described in this specification.

[0446] Embodiment 6 In this embodiment, an electronic device according to an embodiment of the present invention will be described using Figures 20 to 23.

[0447] The electronic device of this embodiment includes a display device according to one embodiment of the present invention. The display device according to one embodiment of the present invention is easily made high-definition, high-resolution, and large-scale. Therefore, the display device according to one embodiment of the present invention can be used in the display section of various electronic devices.

[0448] In addition, the display device of one embodiment of the present invention can be manufactured at low cost, thereby reducing the manufacturing cost of electronic devices.

[0449] As electronic devices, in addition to electronic devices with large screens such as televisions, desktop or laptop personal computers, monitors for computers, digital signage, and large game consoles such as pinball machines, examples include digital cameras, digital video cameras, digital photo frames, mobile phones, portable game consoles, portable information terminals, and audio playback devices.

[0450] In particular, because the display device of one embodiment of the present invention can improve clarity, it can be appropriately used in electronic devices that include a small display section. Examples of such electronic devices include information terminal devices (wearable devices) such as watch-type and bracelet-type devices, VR devices such as head-mounted displays, and AR devices such as glasses-type displays. In addition, SR (alternate reality) devices and MR (mixed reality) devices can also be cited as wearable devices.

[0451] A display device according to one embodiment of the present invention preferably has extremely high resolution, such as HD (1280×720 pixels), FHD (1920×1080 pixels), WQHD (2560×1440 pixels), WQXGA (2560×1600 pixels), 4K2K (3840×2160 pixels), 8K4K (7680×4320 pixels), etc. Particularly preferred is 4K2K, 8K4K, or higher resolution. Furthermore, the pixel density (clarity) in the display device according to one embodiment of the present invention is preferably 300 ppi or more, more preferably 500 ppi or more, further preferably 1000 ppi or more, even more preferably 2000 ppi or more, even more preferably 3000 ppi or more, even more preferably 5000 ppi or more, and even more preferably 7000 ppi or more. By using the aforementioned high-resolution or high-definition display devices, the sense of realism and depth can be further enhanced in personal electronic devices such as portable or home-use devices.

[0452] The electronic device of this embodiment can be assembled along the curved surface of the inner or outer wall of a house or high-rise building, or the interior or exterior decoration of a car.

[0453] The electronic device of this embodiment may also include an antenna. By receiving signals through the antenna, images and information can be displayed on the display unit. In addition, when the electronic device includes an antenna and a secondary battery, contactless power transmission can be performed using the antenna.

[0454] The electronic device of this embodiment may also include a sensor (which has the function of measuring factors such as force, displacement, position, velocity, acceleration, angular velocity, rotational speed, distance, light, liquid, magnetism, temperature, chemical substance, sound, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, tilt, vibration, odor, or infrared radiation).

[0455] The electronic device of this embodiment may have various functions. For example, it may have the following functions: displaying various information (still images, moving images, text images, etc.) on the display unit; touch panel function; displaying calendar, date or time, etc.; executing various software (programs); performing wireless communication function; reading programs or data stored in the storage medium; etc.

[0456] The electronic device 6500 shown in Figure 20A is a portable information terminal device that can be used as a smartphone.

[0457] The electronic device 6500 includes a housing 6501, a display unit 6502, a power button 6503, a button 6504, a speaker 6505, a microphone 6506, a camera 6507, and a light source 6508, etc. The display unit 6502 has a touch panel function.

[0458] The display device of one embodiment of the present invention can be used in the display unit 6502.

[0459] Figure 20B is a cross-sectional view of one end of the microphone 6506 including the housing 6501.

[0460] A light-transmitting protective member 6510 is provided on one side of the display surface of the housing 6501. A display panel 6511, an optical member 6512, a touch sensor panel 6513, a printed circuit board 6517, a battery 6518, etc. are provided in the space surrounded by the housing 6501 and the protective member 6510.

[0461] The display panel 6511, optical component 6512 and touch sensor panel 6513 are fixed to the protective component 6510 using an adhesive layer (not shown).

[0462] In the area outside the display unit 6502, a portion of the display panel 6511 is folded back, and this folded portion is connected to an FPC 6515. An IC 6516 is mounted on the FPC 6515. The FPC 6515 is connected to terminals provided on a printed circuit board 6517.

[0463] The display panel 6511 can use a flexible display (a flexible display device) according to one embodiment of the present invention. This allows for the realization of an extremely lightweight electronic device. Furthermore, since the display panel 6511 is extremely thin, a large-capacity battery 6518 can be installed while minimizing the thickness of the electronic device. Additionally, by folding a portion of the display panel 6511 to provide a connection portion with the FPC 6515 on the back of the pixel portion, a narrow-bezel electronic device can be realized.

[0464] Figure 21A shows an example of a television set. In the television set 7100, a display unit 7000 is assembled in the housing 7101. The structure in which the housing 7101 is supported by a bracket 7103 is shown here.

[0465] A display device according to an embodiment of the present invention can be applied to the display unit 7000.

[0466] The television 7100 shown in FIG. 21A can be operated using the operation switch provided in the housing 7101 and the separately provided remote control 7111. Furthermore, a touch sensor can be provided in the display unit 7000, allowing operation of the television 7100 by touching the display unit 7000 with a finger or the like. Additionally, the remote control 7111 can have a display unit that displays information output from the remote control 7111. Channel and volume controls can be performed using the operation keys or touch panel provided in the remote control 7111, and the images displayed on the display unit 7000 can also be manipulated.

[0467] In addition, the television set 7100 is equipped with a receiver and a modem. It can receive general television broadcasts by using the receiver. Furthermore, it can connect to a wired or wireless communication network by using the modem to conduct one-way (from sender to receiver) or two-way (between sender and receiver or between receivers, etc.) information communication.

[0468] Figure 21B shows an example of a laptop computer. The laptop computer 7200 includes a casing 7211, a keyboard 7212, a pointing device 7213, an external connection port 7214, etc. A display unit 7000 is assembled in the casing 7211.

[0469] A display device according to an embodiment of the present invention can be applied to the display unit 7000.

[0470] Figures 21C and 21D show an example of a digital signage.

[0471] The digital signage 7300 shown in Figure 21C includes a housing 7301, a display unit 7000, and a speaker 7303. In addition, it may also include LED lights, operation keys (including a power switch or operation switch), connection terminals, various sensors, a microphone, etc.

[0472] Figure 21D shows a digital signboard 7400 disposed on a cylindrical column 7401. The digital signboard 7400 includes a display section 7000 disposed along the curved surface of the column 7401.

[0473] In Figures 21C and 21D, a display device according to an embodiment of the present invention can be applied to the display unit 7000.

[0474] The larger the display unit 7000, the more information it can provide at once. The larger the display unit 7000, the easier it is to attract attention, which can improve the effectiveness of advertising.

[0475] By using a touch panel for the display unit 7000, not only can static or dynamic images be displayed on the display unit 7000, but users can also operate it intuitively, which is superior. In addition, when used to provide information such as route information or traffic information, the intuitive operation can improve ease of use.

[0476] As shown in Figures 21C and 21D, the digital signage 7300 or 7400 is preferably able to wirelessly communicate with a user's smartphone or other information terminal device 7311 or 7411. For example, advertising information displayed on the display unit 7000 can be displayed on the screen of the information terminal device 7311 or 7411. Furthermore, the display on the display unit 7000 can be switched by operating the information terminal device 7311 or 7411.

[0477] Furthermore, the game can be executed on the digital signage 7300 or 7400 using the screen of the information terminal device 7311 or 7411 as the operating unit (controller). Thus, multiple users can participate in the game simultaneously and enjoy the experience.

[0478] Figure 22A is an external view of a camera 8000 equipped with a viewfinder 8100.

[0479] The camera 8000 includes a housing 8001, a display unit 8002, an operation button 8003, a shutter button 8004, etc. Furthermore, the camera 8000 is equipped with a detachable lens 8006. In the camera 8000, the lens 8006 and the housing may also be formed as a single unit.

[0480] The camera 8000 can take pictures by pressing the shutter button 8004 or touching the display 8002, which is used as a touch panel.

[0481] The housing 8001 includes an insert with electrodes, which can be connected to the viewfinder 8100 and to a flash unit, etc.

[0482] The viewfinder 8100 includes a housing 8101, a display unit 8102, and buttons 8103, etc.

[0483] The housing 8101 is mounted to the camera 8000 by means of an inserter that fits into the camera 8000. The viewfinder 8100 can display images received from the camera 8000 on the display unit 8102.

[0484] Button 8103 is used as a power button, etc.

[0485] The display device according to one embodiment of the present invention can be used in the display unit 8002 of a camera 8000 and the display unit 8102 of a viewfinder 8100. Alternatively, a viewfinder may be built into the camera 8000.

[0486] Figure 22B is an external view of the head-mounted display 8200.

[0487] The head-mounted display 8200 includes a mounting section 8201, a lens 8202, a main body 8203, a display section 8204, and a cable 8205. In addition, a battery 8206 is built into the mounting section 8201.

[0488] Power is supplied from the battery 8206 to the main body 8203 via cable 8205. The main body 8203 is equipped with a wireless receiver, etc., and can display the received image information, etc., on the display unit 8204. In addition, the main body 8203 is equipped with a camera, thereby utilizing information from the user's eyeball or eyelid movements as an input method.

[0489] Furthermore, multiple electrodes can be provided at the location of the mounting unit 8201 that is touched by the user to detect the current flowing through the electrodes according to the user's eye movements, thereby realizing the function of recognizing the user's gaze. In addition, it can also have the function of monitoring the user's pulse based on the current flowing through the electrodes. The mounting unit 8201 can have various sensors such as temperature sensors, pressure sensors, and acceleration sensors, and can also have the function of displaying the user's biometric information on the display unit 8204 or the function of changing the image displayed on the display unit 8204 in sync with the user's head movements.

[0490] The display device of one embodiment of the present invention can be used in the display unit 8204.

[0491] Figures 22C to 22E are external views of the head-mounted display 8300. The head-mounted display 8300 includes a housing 8301, a display unit 8302, a strap-shaped fixing tool 8304, and a pair of lenses 8305.

[0492] The user can see the display on the display unit 8302 through the lens 8305. Preferably, the display unit 8302 is curved. This allows the user to experience a high degree of realism. Furthermore, by viewing the images displayed on different areas of the display unit 8302 through the lens 8305, three-dimensional displays utilizing parallax can be performed. In addition, one embodiment of the present invention is not limited to a structure with one display unit 8302, and two display units 8302 may be provided, with one display unit for each of the user's eyes.

[0493] The display device according to one embodiment of the present invention can be used in the display unit 8302. The display device according to one embodiment of the present invention can also achieve extremely high resolution. For example, as shown in FIG22E, even when the display is magnified using the lens 8305, the pixels are not easily visible to the user. That is to say, the display unit 8302 can be used to enable the user to see images with a higher degree of realism.

[0494] Figure 22F is an external view of the goggle-type head-mounted display 8400. The head-mounted display 8400 includes a pair of housings 8401, a mounting part 8402, and a buffer member 8403. Each of the pair of housings 8401 is provided with a display part 8404 and a lens 8405. By displaying different images on the pair of display parts 8404, three-dimensional display utilizing parallax can be performed.

[0495] The user can see the display on the display unit 8404 through the lens 8405. The lens 8405 has a focus adjustment mechanism that can adjust the position of the lens 8405 according to the user's vision. The display unit 8404 is preferably square or a horizontally elongated rectangle. This can improve the realism.

[0496] The mounting part 8402 is preferably plastic and elastic so that it can be adjusted according to the user's face size without falling off. Additionally, a portion of the mounting part 8402 preferably has a vibration mechanism that functions as a bone conduction headphone. Thus, simply installing the headphone allows users to enjoy video and sound without the need for headphones, speakers, or other audio equipment. Furthermore, it may also have the function of wirelessly outputting audio data to the housing 8401.

[0497] The mounting part 8402 and the buffer member 8403 are the parts that come into contact with the user's face (forehead, cheeks, etc.). By ensuring that the buffer member 8403 is in close contact with the user's face, light leakage can be prevented, thereby further enhancing the immersive experience. The buffer member 8403 is preferably made of a soft material to ensure close contact with the user's face when the user wears the head-mounted display 8400. For example, materials such as rubber, silicone rubber, polyurethane, and sponge can be used. Furthermore, when a component with a surface covered by cloth or leather (natural or synthetic leather) is used as the buffer member 8403, gaps are less likely to form between the user's face and the buffer member 8403, thus appropriately preventing light leakage. Additionally, using such a material not only provides a skin-friendly feel but also prevents the user from feeling cold when wearing the device, especially in colder seasons. It is preferable when components that come into contact with the user's skin, such as the cushioning member 8403 or the mounting part 8402, are detachable, making them easy to clean and replace.

[0498] The electronic device shown in Figures 23A to 23F includes a housing 9000, a display unit 9001, a speaker 9003, operation keys 9005 (including a power switch or operation switch), a connection terminal 9006, a sensor 9007 (which has the function of measuring the following factors: force, displacement, position, velocity, acceleration, angular velocity, rotational speed, distance, light, liquid, magnetism, temperature, chemical substance, sound, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, tilt, vibration, odor, or infrared radiation), a microphone 9008, etc.

[0499] The electronic devices shown in Figures 23A to 23F have various functions. For example, they may have the following functions: displaying various information (still images, moving images, and text images, etc.) on a display unit; a touch panel function; displaying a calendar, date, or time, etc.; controlling processing using various software (programs); performing wireless communication; reading and processing programs or data stored in a storage medium; etc. Note that the functions that an electronic device may have are not limited to the above functions, but may have various functions. An electronic device may include multiple display units. In addition, a camera or the like may be installed in the electronic device to enable it to have the following functions: capturing still images or moving images and storing the captured images in a storage medium (external storage medium or storage medium built into the camera); displaying the captured images on a display unit; etc.

[0500] The display device according to one embodiment of the present invention can be used in the display unit 9001.

[0501] The electronic devices shown in Figures 23A to 23F will now be described in detail.

[0502] Figure 23A is a perspective view showing a portable information terminal 9101. The portable information terminal 9101 can be used, for example, as a smartphone. Note that a speaker 9003, a connection terminal 9006, a sensor 9007, etc., can also be provided in the portable information terminal 9101. Furthermore, as a portable information terminal 9101, text and image information can be displayed on multiple surfaces. Examples of three illustrations 9050 are shown in Figure 23A. In addition, information 9051, shown as a dashed rectangle, can be displayed on other surfaces of the display unit 9001. Examples of information 9051 include notifications of received emails, SNS messages, or phone calls; the subject of emails, SNS messages, etc.; the sender's name of emails or SNS messages, etc.; the date; the time; the remaining battery level; and the display of antenna signal strength, etc. Alternatively, illustrations 9050 can be displayed in the same locations where information 9051 is displayed.

[0503] Figure 23B is a perspective view showing a portable information terminal 9102. The portable information terminal 9102 has the function of displaying information on three or more surfaces of the display unit 9001. Here, examples are shown where information 9052, information 9053, and information 9054 are displayed on different surfaces. For example, when the portable information terminal 9102 is placed in a jacket pocket, the user can check information 9053 displayed in a position seen from above the portable information terminal 9102. The user can check this display without taking the portable information terminal 9102 out of the pocket, thereby, for example, determining whether to answer a phone call.

[0504] Figure 23C is a perspective view showing a watch-type portable information terminal 9200. The portable information terminal 9200 can be used, for example, as a smartwatch (registered trademark). Furthermore, the display surface of the display unit 9001 is curved, allowing display along its curved surface. Additionally, the portable information terminal 9200 can perform hands-free calls, for example, by communicating with a headset capable of wireless communication. Furthermore, by utilizing the connection terminal 9006, the portable information terminal 9200 can transmit data and charge with other information terminals. Charging can also be performed wirelessly.

[0505] Figures 23D to 23F are perspective views showing the foldable portable information terminal 9201. Furthermore, Figure 23D is a perspective view of the portable information terminal 9201 in its unfolded state, Figure 23F is a perspective view of its folded state, and Figure 23E is a perspective view of the intermediate state during the transition from one of the states in Figures 23D and 23F to the other. The portable information terminal 9201 offers good portability in its folded state, and in its unfolded state, it provides a large, seamless display area, resulting in excellent browsing capabilities. The display unit 9001 included in the portable information terminal 9201 is supported by three housings 9000 connected by hinges 9055. The display unit 9001 can be bent, for example, within a radius of curvature of 0.1 mm or more and 150 mm or less.

[0506] At least a portion of the structural examples shown in this embodiment and the corresponding drawings can be appropriately combined with other structural examples or drawings. Example

[0507] In this embodiment, the pixel electrode 111 is fabricated by the method shown in FIG9A to FIG9F, and the EL layer 112 is fabricated on the pixel electrode 111 by the method shown in FIG10A to FIG10C. The results are observed using a scanning electron microscope (SEM).

[0508] In this embodiment, sample 1A is manufactured by forming an EL layer 112 on the pixel electrode 111 using the method shown in FIGS. 9A to 10C. Alternatively, as a conventional example, sample 1B is manufactured using a different method than that shown in FIGS. 9A to 10C. In samples 1A and 1B, the distance between adjacent pixels is designed to be 700 nm. In samples 1A and 1B, multiple structures with the EL layer 112 formed on the pixel electrode 111 are manufactured, and cross-sectional images are captured during each process.

[0509] The manufacturing methods of Sample 1A and Sample 1B will be described below. First, the manufacturing method of pixel electrode 111 will be described with reference to Figures 9A to 9F.

[0510] First, as shown in FIG9A, in Sample 1A and Sample 1B, an insulating layer 101a, a conductive film 111aA, a conductive film 111bA, a conductive film 111cA and a conductive film 111dA are sequentially deposited on a silicon substrate.

[0511] The insulating layer 101a is a silicon oxide film deposited using PECVD. The conductive film 111aA is a 50 nm thick titanium film deposited using DC sputtering. The conductive film 111bA is a 70 nm thick aluminum film deposited using DC sputtering. The conductive film 111cA is a 6 nm thick titanium film deposited using DC sputtering. Conductive films 111aA, 111bA, and 111cA are deposited continuously without exposure to the atmosphere. After deposition, conductive films 111aA, 111bA, and 111cA are heat-treated at 300°C for 1 hour in an atmospheric atmosphere, thereby oxidizing conductive film 111cA to form titanium oxide.

[0512] In addition, the conductive film 111dA is a 10 nm thick indium tin oxide film containing silicon. The conductive film 111dA is deposited using an indium tin oxide target containing 5 wt% silicon oxide and by DC sputtering.

[0513] Next, as shown in FIG9A, a photoresist mask 115a is formed on the conductive film 111dA in samples 1A and 1B. A positive photoresist with a thickness of 700 nm is used as the photoresist mask 115a.

[0514] Next, only sample 1A is heat-treated, as shown in FIG9B, to form a photoresist mask 115b with a conical shape on the side when viewed in cross-section. Here, the conditions for the heat treatment are atmospheric atmosphere, 150°C, and 150 seconds.

[0515] Here, Figures 24A and 24B show bird's-eye views of the photoresist mask 115b of sample 1A and the photoresist mask 115a of sample 1B. Figures 24A and 24B were taken using a scanning electron microscope SU8030 manufactured by Hitachi High Technology Co., Ltd. of Japan at an accelerating voltage of 5kV.

[0516] As shown in Figure 24B, the photoresist mask 115a without heat treatment is rectangular. In contrast, as shown in Figure 24A, the side of the photoresist mask 115b that has undergone heat treatment is conical.

[0517] Next, in samples 1A and 1B, as shown in FIG9C, the conductive film 111dA is wet-etched to form the conductive layer 111d. ITO-07N (manufactured by Kanto Chemical Co., Ltd., Japan) is used in the wet etching of the conductive film 111dA.

[0518] Next, only in sample 1A, as shown in FIG9D, conductive films 111cA and 111bA were dry-etched to form conductive layers 111c and 111b. In the dry etching of conductive films 111cA and 111bA, BCl3 gas at 60 sccm and Cl2 gas at 20 sccm were used as etching gases, the pressure was 1.9 Pa, the ICP power was 450 W, the bias power was 100 W, and the substrate temperature was 70 °C.

[0519] Here, as shown in FIG9D, the photoresist mask 115b is also etched to form a reduced photoresist mask 115c. While the photoresist mask 115b with a conical shape is reduced to the photoresist mask 115c, the conductive layer 111c and the conductive layer 111b are etched, thereby making the sides of the conductive layer 111c and the conductive layer 111b have a conical shape.

[0520] In sample 1A, the dry etching described above stops before the conductive film 111aA is etched. On the other hand, in sample 1B, dry etching is performed in the same way, but under the above conditions, the etching proceeds to the conductive film 111aA to form the conductive layer 111a.

[0521] Next, only in sample 1A, as shown in FIG9E, the conductive film 111aA was dry-etched to form the conductive layer 111a. In the dry etching of the conductive film 111aA, BCl3 gas at 40 sccm and CF4 gas at 40 sccm were used as etching gases, the pressure was 1.9 Pa, the ICP power was 500 W, the bias power was 300 W, and the substrate temperature was 70 °C.

[0522] As shown in Figure 9E, the photoresist mask 115c is also etched to form a further reduced photoresist mask 115d. At this time, while the conductive layer 111a is being etched, the conductive layers 111b and 111c are also being further etched.

[0523] Here, in the dry etching according to FIG. 9E, the etching rate of conductive layers 111a to 111c is reduced by decreasing the amount of chlorine gases (BCl3 and Cl2) and introducing fluorine gases (CF4) to reduce the vapor pressure of the reaction products. Furthermore, the etching rate of the photoresist (photoresist mask 115d) is increased by increasing the bias power. That is, the dry etching according to FIG. 9E is performed under conditions where the photoresist etching rate is higher and the etching rate of the pixel electrode 111 (typically the titanium oxide film of conductive layer 111c) is lower compared to the dry etching according to FIG. 9D.

[0524] Specifically, in the dry etching according to Figure 9D, the etching rate of the photoresist is 128.8 nm / min, and the etching rate of the titanium film is 207.6 nm / min. The photoresist / titanium etching selectivity ratio is approximately 0.6. On the other hand, in the dry etching according to Figure 9E, the etching rate of the photoresist is 167.9 nm / min, and the etching rate of the titanium oxide film is 116.3 nm / min. The photoresist / titanium oxide etching selectivity ratio is approximately 1.4.

[0525] Thus, by etching under the condition that the etching rate of the photoresist is greater than the etching rate of the titanium oxide film, the photoresist mask 115d can be further reduced in the etching according to FIG. 9E. As a result, etching can be performed with the area of ​​conductive layer 111a to conductive layer 111c exposed from the photoresist mask 115d being increased, so the side surfaces of conductive layer 111a to conductive layer 111c can be tapered.

[0526] Next, as shown in FIG9F, in samples 1A and 1B, the photoresist mask (photoresist mask 115d in sample 1A) on the conductive layer 111d is removed by plasma ashing using oxygen gas. As a result, in samples 1A and 1B, pixel electrodes 111 (conductive layers 111a, 111b, 111c, and 111d) can be formed on the insulating layer 101a.

[0527] Here, Figures 25A and 25B show cross-sectional images of the pixel electrode 111 of sample 1A and the pixel electrode 111 of sample 1B. Figures 25A and 25B were taken using a scanning electron microscope SU8030 manufactured by Hitachi High Technology Co., Ltd. of Japan at an accelerating voltage of 5kV.

[0528] It can be seen that in sample 1B, where the photoresist mask 115b is not tapered and the etching rate of the photoresist mask 115d is not increased, the side of the pixel electrode 111 is steeply rectangular. The cone angle θ of sample 1B is 89.4°. In addition, a portion of the aluminum film of the conductive layer 111b is etched, resulting in a shape where the conductive layer 111b is recessed relative to the conductive layers 111a and 111c.

[0529] In contrast, in sample 1A, the side of the pixel electrode 111 is tapered with a cone angle θ of 43.5°. As shown in FIG3A, a portion of the conductive layer 111d is recessed relative to the conductive layer 111b, etc. Furthermore, as shown in FIG2B, a recess is formed in the region of the insulating layer 101a that does not overlap with the pixel electrode 111.

[0530] Thus, as shown in FIG10A, a plurality of pixel electrodes 111 can be formed in samples 1A and 1B. Next, a method for forming an EL layer 112 on the pixel electrodes 111 in samples 1A and 1B according to FIG10B and 10C will be described. Note that in FIG10B and 10C, etc., the symbols are marked with R, G or B, but they are omitted in the description in this embodiment.

[0531] First, as shown in FIG10B, in Sample 1A and Sample 1B, an EL film 112f and a sacrificial film 144 are sequentially deposited on the pixel electrode 111.

[0532] An EL film 112f was deposited sequentially using a vapor deposition method, consisting of a hole injection layer, a hole transport layer, a light-emitting layer, and an electron transport layer. The thickness of the EL film 112f was approximately 280 nm.

[0533] The sacrificial film 144 has a stacked structure of sacrificial film 144a and sacrificial film 144b on sacrificial film 144a. Sacrificial film 144a is a 30 nm thick alumina film deposited by ALD method. In addition, sacrificial film 144b is a 50 nm thick tungsten film deposited by DC sputtering method.

[0534] Next, as shown in FIG10B, a photoresist mask 143a is formed on the sacrificial film 144 in samples 1A and 1B. A positive photoresist with a thickness of 700 nm is used as the photoresist mask 143a.

[0535] Next, in samples 1A and 1B, a sacrificial layer 145b is formed by dry etching of the sacrificial film 144b using a photoresist mask 143a. In the dry etching of the sacrificial film 144b, 50 sccm of SF6 gas is used as the etching gas, the pressure is 2.0 Pa, the ICP power is 700 W, the bias power is 10 W, and the substrate temperature is 10 °C.

[0536] Here, Figures 26A and 27A show cross-sectional images of Sample 1A and Sample 1B. Figures 26A and 27A were captured using a scanning electron microscope SU8030 manufactured by Hitachi High Technology Co., Ltd., Japan, with an accelerating voltage of 5 kV. Note that the cross-sectional images of Figures 26B to 26D, 27B to 27D, and 28, which will be described later, were also captured under the same conditions. Note that in Figures 26B to 26D, 27B to 27D, and 28, there are cross-sectional images showing the EL film 112f or EL layer 112 peeling off from the pixel electrode 111, which occurs during the manufacturing of the photographic samples.

[0537] In sample 1B shown in FIG. 27A, the top surface of the EL film 112f has steep irregularities, and the sacrificial film 144a is deposited in a recess of the EL film 112f above the end of the pixel electrode 111. In contrast, in sample 1A shown in FIG. 26A, the top surface of the EL film 112f has a smooth slope. Therefore, the sacrificial film 144a is not embedded in the EL film 112f.

[0538] Next, in samples 1A and 1B, the photoresist mask 143a was removed by plasma ashing using oxygen gas. In the plasma ashing using oxygen gas, O2 gas was used at 80 sccm, the pressure was 5.0 Pa, the ICP power was 800 W, the bias power was 10 W, and the substrate temperature was 10 °C.

[0539] Here, Figures 26B and 27B show cross-sectional images of samples 1A and 1B. In sample 1B shown in Figure 27B, the sacrificial film 144a is also embedded in the recess of the EL film 112f above the end of the pixel electrode 111 after the photoresist mask 143a is removed. In sample 1A shown in Figure 26B, no particular changes other than the removal of the photoresist mask 143a are confirmed.

[0540] Next, in samples 1A and 1B, the sacrificial layer 145b is used as a mask to dry etch the sacrificial film 144a to form the sacrificial layer 145a. During the dry etching of the sacrificial film 144a, a CHF3 / He mixed gas treatment and an O2 gas treatment are performed, and these treatments are repeated. In the CHF3 / He mixed gas treatment, CHF3 gas at 7.5 sccm and He gas at 142.5 sccm are used as the etching gases, the pressure is 5.5 Pa, the ICP power is 475 W, the bias power is 150 W, and the substrate temperature is 10 °C. In the O2 gas treatment, O2 gas at 80 sccm is used, the pressure is 2.0 Pa, the ICP power is 300 W, the bias power is 10 W, and the substrate temperature is 10 °C.

[0541] Here, Figures 26C and 27C show cross-sectional images of samples 1A and 1B. In sample 1B shown in Figure 27C, a residue 145c made of alumina is also formed in the recess of the EL film 112f above the end of the pixel electrode 111 after the sacrificial layer 145a is formed. In sample 1A shown in Figure 26C, the alumina film other than the sacrificial layer 145a is removed.

[0542] Next, as shown in FIG10C, in samples 1A and 1B, the EL film 112f is dry-etched using the sacrificial layer 145 to form the EL layer 112. During the dry etching of the EL film 112f, a mixed gas treatment of H2 / Ar and an O2 gas treatment are performed. In the H2 / Ar mixed gas treatment, 12 sccm of H2 gas and 36 sccm of Ar gas are used as the etching gases, the pressure is 1.0 Pa, the ICP power is 600 W, and the substrate temperature is 10 °C. The initial bias power is 100 W, which is continuously varied to 50 W for dry etching. In the O2 gas treatment, 48 sccm of O2 gas is used, the pressure is 1.0 Pa, the ICP power is 600 W, the bias power is 25 W, and the substrate temperature is 10 °C.

[0543] Here, Figures 26D and 27D show cross-sectional images of samples 1A and 1B. Figure 28 shows a bird's-eye view of sample 1A. In sample 1B shown in Figure 27D, during the formation of the EL layer 112, residue 145c is used as a mask, and a structure 112a with the EL layer formed under the alumina is formed. The structure 112a is formed as a wall along the recess between the pixel electrodes 111. If the processes shown in Figures 10D to 10F are performed with the structure 112a remaining, the same structure as structure 112a is repeatedly formed between the pixel electrodes 111. If multiple such structures are formed between the pixel electrodes 111, it results in the disconnection of the common layer 114 and the common electrode 113 formed thereon.

[0544] In contrast, in sample 1A shown in FIG26D, although some residue was found on the pixel electrode 111, no wall-like structures such as structure 112a were found. Therefore, as shown in this embodiment, by making the side of the pixel electrode 111 tapered, the formation of wall-like structures between the pixel electrodes 111 can be suppressed, thereby improving the display quality of the display device. [Simplified Explanation of the Diagram]

[0024] Figures 1A to 1C are diagrams showing examples of the structure of a display device. Figures 2A to 2C are diagrams showing examples of the structure of a display device. Figures 3A to 3C are diagrams showing examples of the structure of a display device. Figures 4A and 4B are diagrams showing examples of the structure of a display device. Figures 5A to 5D are diagrams showing examples of the structure of a display device. Figures 6A to 6D are diagrams showing examples of the structure of a display device. Figures 7A to 7F are top views showing examples of the structure of a pixel. Figures 8A to 8E are top views showing examples of the structure of a pixel. Figures 9A to 9F are diagrams showing examples of a manufacturing method for a display device. Figures 10A to 10F are diagrams showing examples of a manufacturing method for a display device. Figures 11A to 11E are diagrams showing examples of a manufacturing method for a display device. [Fig. 12] is a perspective view showing an example of a display device. [Fig. 13A] is a cross-sectional view showing an example of a display device. [Fig. 13B] to [Fig. 13D] are cross-sectional views showing an example of a transistor. [Fig. 14A] and [Fig. 14B] are perspective views showing an example of a display module. [Fig. 15] is a cross-sectional view showing an example of a display device. [Fig. 16] is a cross-sectional view showing an example of a display device. [Fig. 17] is a cross-sectional view showing an example of a display device. [Fig. 18] is a cross-sectional view showing an example of a display device. [Fig. 19A] to [Fig. 19F] are diagrams showing examples of the structure of a light-emitting element. [Fig. 20A] and [Fig. 20B] are diagrams showing an example of an electronic device. [Fig. 21A] to [Fig. 21D] are diagrams showing an example of an electronic device. [Fig. 22A] to [Fig. 22F] are diagrams showing an example of an electronic device. [Fig. 23A] to [Fig. 23F] are diagrams showing an example of an electronic device. Figures 24A and 24B are bird's-eye view images according to this embodiment. Figures 25A and 25B are cross-sectional images according to this embodiment. Figures 26A to 26D are cross-sectional images according to this embodiment. Figures 27A to 27D are cross-sectional images according to this embodiment. Figure 28 is a bird's-eye view image according to this embodiment.

Claims

1. A display device, comprising: First pixel; The display device also includes a second pixel disposed adjacent to the first pixel, wherein the first pixel includes a first pixel electrode, a first EL layer on the first pixel electrode, and a common electrode on the first EL layer; the second pixel includes a second pixel electrode, a second EL layer on the second pixel electrode, and the common electrode on the second EL layer; both the side surface of the first pixel electrode and the side surface of the second pixel electrode have a tapered shape, the cone angle of the tapered shape being less than 90°; and the display device has a region where the distance between the first pixel electrode and the second pixel electrode is less than 1 μm.

2. The display device as described in claim 1 further includes: First insulating layer; And a second insulating layer on the first insulating layer, wherein the first insulating layer comprises an inorganic material, the second insulating layer comprises an organic material, and the second insulating layer is opposite to the side of the first EL layer and the side of the second EL layer through the first insulating layer.

3. The display device of claim 2, wherein the first insulating layer covers the side surface of the first pixel electrode, the side surface of the first EL layer, the side surface of the second pixel electrode, and the side surface of the second EL layer.

4. The display device of claim 1, wherein the first pixel electrode and the second pixel electrode each include a first conductive layer, a second conductive layer on the first conductive layer, a third conductive layer on the second conductive layer, and a fourth conductive layer on the third conductive layer, the second conductive layer being reflective, the first conductive layer and the third conductive layer having the function of protecting the second conductive layer, the fourth conductive layer having a larger work function than the third conductive layer, and the third conductive layer and the fourth conductive layer being light-transmitting.

5. The display device of claim 4, wherein the first conductive layer comprises titanium.

6. The display device of claim 4, wherein the second conductive layer comprises aluminum.

7. The display device of claim 4, wherein the third conductive layer comprises titanium oxide.

8. The display device of claim 4, wherein the fourth conductive layer comprises an oxide containing one or more of indium, tin, zinc, gallium, titanium, aluminum and silicon.

9. The display device of claim 1, wherein the first pixel includes a common layer disposed between the first EL layer and the common electrode, and the second pixel includes the common layer between the second EL layer and the common electrode.

10. A method for manufacturing a display device, comprising the following steps in manufacturing a plurality of pixel electrodes including a first conductive layer, a second conductive layer, a third conductive layer, and a fourth conductive layer: sequentially depositing a first conductive film, a second conductive film, a third conductive film, and a fourth conductive film on an insulating layer; forming a photoresist mask with a conical shape on the fourth conductive film; processing the fourth conductive film into the fourth conductive layer using wet etching; processing the third conductive film and the second conductive film into the third conductive layer and the second conductive layer using a first dry etching; and processing the first conductive film into the first conductive layer using a second dry etching and further etching the second conductive layer and the third conductive layer, wherein... The etching rate of the photoresist mask in the second dry etching is greater than the etching rate of the third conductive layer, and the distance between the first conductive layer included in one of the plurality of pixel electrodes and the first conductive layer included in another of the plurality of pixel electrodes is less than 1 μm.

11. A method for manufacturing a display device as claimed in claim 10, wherein chlorine gas and fluorine gas are used in the second dry etching.

12. A method for manufacturing a display device as claimed in claim 10, wherein the bias power in the second dry etching is greater than that in the first dry etching.

13. A method for manufacturing a display device as claimed in claim 10, wherein heat treatment is performed in an oxygen-containing atmosphere after the third conductive film is deposited.

14. A method for manufacturing a display device as claimed in claim 10, wherein the first conductive film and the third conductive film comprise titanium.

15. A method of manufacturing a display device as claimed in claim 10, wherein the second conductive film comprises aluminum.

16. A method of manufacturing a display device as claimed in claim 10, wherein the fourth conductive film comprises an oxide containing one or more of indium, tin, zinc, gallium, titanium, aluminum and silicon.

Images