Method for manufacturing display devices

Abstract

A method for manufacturing a display device that easily achieves high definition is provided. A display device combining high display quality and high definition is also provided. In this manufacturing method, a first EL film is deposited on a first pixel electrode and a second pixel electrode, and a first sacrificial film is formed to cover the first EL film. The first sacrificial film and the first EL film are etched to expose the second pixel electrode, and a first EL layer on the first pixel electrode and a first sacrificial layer on the first EL layer are formed, and the first sacrificial layer is removed. The first EL film and the second EL film are etched by dry etching, and the first sacrificial layer is removed by wet etching.

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 field. Examples of technical fields within the scope of 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, and methods for driving or manufacturing the aforementioned 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 surveillance equipment are also being required to achieve higher resolutions. Furthermore, devices that most strongly demand high definition include those used in virtual reality (VR) or augmented reality (AR).

[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 light-emitting organic compound is sandwiched between a pair of electrodes. By applying a voltage to the element, light emission from the light-emitting 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 1] Japanese Patent Application Publication No. 2002-324673 [Summary of the Invention]

[0007] One objective of one embodiment of the present invention is to provide a method for manufacturing a display device that easily achieves high definition. Another objective of one embodiment of the present invention is to provide a display device that combines high display quality and high definition. Another objective of one embodiment of the present invention is to provide a display device with high contrast. Another objective of one embodiment of the present invention is to provide a display device with high reliability.

[0008] 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.

[0009] Note that the description of the above objectives does not preclude the existence of other objectives. One embodiment of the present invention does not necessarily need to achieve all of the above objectives. Objectives other than those described above can be extracted from the description in the specification, drawings, claims, etc.

[0010] One embodiment of the present invention is a method for manufacturing a display device, comprising the following processes: a first process of depositing a first EL film on a first pixel electrode and a second pixel electrode; a second process of forming a first sacrificial film to cover the first EL film; a third process of etching the first sacrificial film and the first EL film to expose a second pixel electrode and forming a first EL layer on the first pixel electrode and a first sacrificial layer on the first EL layer; a fourth process of depositing a second EL film on the first sacrificial layer and the second pixel electrode; a fifth process of forming a second sacrificial film to cover the second EL film; a sixth process of etching the second sacrificial film and the second EL film to expose the first sacrificial layer and forming a second EL layer on the second pixel electrode and a second sacrificial layer on the second EL layer; a seventh process of removing the first sacrificial layer and the second sacrificial layer; and an eighth process of drying the first EL layer and the second EL layer. Furthermore, the first EL film and the second EL film are etched by dry etching, and the first sacrificial layer and the second sacrificial layer are removed by wet etching.

[0011] Furthermore, in the above method, the first sacrificial film is preferably a resin material that is soluble in water or alcohol. Also, preferably, in the third process, the first sacrificial film and the first EL film are continuously etched by dry etching in an oxygen-containing atmosphere. And, preferably, in the seventh process, the first sacrificial layer and the second sacrificial layer are removed by dissolving in water or alcohol.

[0012] Furthermore, in the above method, the first sacrificial film preferably includes a metal film, an alloy film, a metal oxide film, a semiconductor film, or an inorganic insulating film. Also, preferably, in the third process, the first EL film is etched by dry etching using an etching gas whose main component does not contain oxygen. Furthermore, preferably, in the seventh process, the first sacrificial layer and the second sacrificial layer are removed by wet etching using a tetramethylammonium hydroxide aqueous solution (TMAH), dilute hydrofluoric acid, oxalic acid, phosphoric acid, acetic acid, nitric acid, or a mixture thereof.

[0013] In addition, any of the above methods preferably includes a ninth process for forming a hard mask between the second process and the third process. Furthermore, it is preferable that, in the third process, after etching the first sacrificial film using the hard mask, the hard mask and the first EL film are etched using the same process.

[0014] In addition, in any of the above methods, the first EL layer and the second EL layer are preferably processed in a strip-like manner with their top surfaces shaped like strips. Alternatively, they are preferably processed in an island-like manner with their top surfaces shaped like islands.

[0015] Furthermore, any of the above methods preferably includes a tenth process after the eighth process, in which a common electrode is formed on the first EL layer and the second EL layer. And, preferably, it also includes an eleventh process in which a protective layer is formed on the common electrode.

[0016] In addition, any of the above methods is preferably a twelfth process that forms a common layer on the first EL layer and the second EL layer after the eighth process and before the tenth process.

[0017] In addition, any of the above methods preferably includes a thirteenth process before the first process, in which optical adjustment layers of different thicknesses are formed on the first pixel electrode and the second pixel electrode.

[0018] Another embodiment of the present invention is a method for manufacturing a display device, comprising the following processes: a first process of depositing an EL film on a first pixel electrode and a second pixel electrode; a second process of forming a sacrificial film in a manner covering the EL film; a third process of etching the sacrificial film and the EL film to form a first EL layer on the first pixel electrode, a first sacrificial layer on the first EL layer, a second EL layer on the second pixel electrode, and a second sacrificial layer on the second EL layer; a fourth process of removing the first sacrificial layer and the second sacrificial layer; and a fifth process of drying the first EL layer and the second EL layer. In the third process, the EL film is etched by dry etching. In the fourth process, the first sacrificial layer is removed by wet etching. The EL film also includes a light-emitting layer that emits white light.

[0019] According to one embodiment of the present invention, a method for manufacturing a display device that easily achieves high definition can be provided. Furthermore, according to one embodiment of the present invention, a display device that combines high display quality and high definition can be provided. Furthermore, according to one embodiment of the present invention, a display device with high contrast can be provided. Furthermore, according to one embodiment of the present invention, a display device with high reliability can be provided.

[0020] Furthermore, 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. Additionally, according to one embodiment of the present invention, a method for manufacturing the aforementioned display device with high yield can be provided. Furthermore, according to one embodiment of the present invention, at least one of the problems of the prior art can be improved.

[0021] Note that the description of the above effects does not preclude the existence of other effects. An embodiment of the present invention does not necessarily need to have all the above effects. Effects other than those described above can be extracted from the description in the specification, drawings, claims, etc.

Implementation Method

[0023] Hereinafter, embodiments will be described with reference to the drawings. However, embodiments can be implemented in many different ways, and those skilled in the art will readily understand that the manner and details can be varied in various forms 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 embodiments shown below.

[0024] Note that in the structure of the invention described below, the same symbols are used in common across different figures to represent the same parts or parts having the same function, and repeated descriptions are omitted. Furthermore, when representing parts having the same function, the same shading lines are sometimes used without additional symbols.

[0025] Note that in the various figures described in this specification, the size of each component, the thickness of a layer, and the area are sometimes exaggerated for clarity. Therefore, the present invention is not limited to the dimensions shown in the figures.

[0026] 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.

[0027] Furthermore, in this specification and other materials, the terms "film" and "layer" may be interchanged. For example, sometimes the terms "conductive layer" or "insulating layer" may be replaced with "conductive film" or "insulating film".

[0028] Note that in this specification, the EL layer refers to a layer disposed between a pair of electrodes of the 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.

[0029] 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.

[0030] Furthermore, in this specification and the like, a structure in which connectors such as flexible printed circuits (FPC) or tape-and-reel packages (TCP) are mounted on the substrate of a display panel, or a structure in which ICs (integrated circuits) are directly mounted on the substrate by means of chip-on-glass bonding (COG), is sometimes referred to as a display panel module or display module, or simply as a display panel, etc.

[0031] 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.

[0032] One embodiment of the present invention is a display device including light-emitting elements (also referred to as 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. The light-emitting elements are preferably organic EL elements (organic electroluminescent elements). Two or more light-emitting elements that emit light of different colors each include an EL layer comprising different materials. For example, a full-color display device can be realized by including three light-emitting elements that emit red (R), green (G), or blue (B) light respectively.

[0033] Here, it is known that when forming EL layers between light-emitting elements of different colors, a vapor deposition method using a shadow mask such as a metal mask is employed. However, this method suffers from various influences, such as the precision of the metal mask, misalignment between the metal mask and the substrate, deflection of the metal mask, and enlargement of the deposited film profile due to vapor scattering, resulting in deviations in the shape and position of the island-shaped organic film from the designed shape and position, making it difficult to achieve high resolution and high aperture ratio. Therefore, special pixel arrangement methods such as pentile arrangement have been adopted to tentatively improve resolution (also known as pixel density).

[0034] In one embodiment of the present invention, the EL layer is processed into a fine pattern without the use of a shadow mask such as a metal mask. This allows for the realization of a display device with high definition and a large aperture ratio, which has been difficult to achieve until now. Furthermore, because the EL layers can be formed separately, an extremely vivid display device with extremely high contrast and extremely high display quality can be realized.

[0035] For simplicity, the case of forming EL layers for light-emitting elements of two different colors will be described here. First, a first EL film and a first sacrificial film are stacked to cover two pixel electrodes. Next, a photoresist mask is formed on the first sacrificial film at a position overlapping one of the pixel electrodes (first pixel electrode). Then, the photoresist mask, a portion of the first sacrificial film, and a portion of the first EL film are etched. At this point, the etching ends when the other pixel electrode (second pixel electrode) is exposed. Thus, a portion of the first EL film (also called the first EL layer) processed into a strip or island shape can be formed on the first pixel electrode, and a portion of the sacrificial film (also called the first sacrificial layer) can be formed thereon.

[0036] Next, a second EL film and a second sacrificial film are stacked to form. Then, photoresist masks are formed at locations overlapping the first pixel electrode and the second pixel electrode, respectively. Next, a portion of the photoresist mask, a portion of the second sacrificial film, and a portion of the second EL film are etched in the same manner as described above. As a result, the first EL layer and the first sacrificial layer are disposed on the first pixel electrode, and the second EL layer and the second sacrificial layer are disposed on the second pixel electrode. Thus, the first EL layer and the second EL layer can be formed separately. Finally, the first sacrificial layer and the second sacrificial layer are removed to form a common electrode, thereby enabling the formation of light-emitting elements of two colors.

[0037] Furthermore, by repeatedly performing the above process, EL layers of three or more light-emitting elements can be formed, thereby realizing a display device including three or four or more light-emitting elements.

[0038] For example, in the method of forming a metal mask, it is difficult to set the spacing between EL layers of different colors to be less than 10 μm. However, according to the method described above, this spacing can be reduced to less than 3 μm, less than 2 μm, or less than 1 μm. For example, by using an exposure apparatus for LSI manufacturing, this spacing can be further 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 can exist between two light-emitting elements can be significantly reduced, and the aperture ratio can be made approximately 100%. For example, aperture ratios of 50% or more, 60% or more, 70% or more, 80% or more, or even 90% or more, and less than 100% can also be achieved.

[0039] Furthermore, compared to the case where a metal mask is used, the pattern of the EL layer itself can be made extremely small. Additionally, when forming the EL layer separately using a metal mask, for example, uneven thickness occurs at the center and ends of the pattern, resulting in a smaller effective area usable as a light-emitting region relative to the overall area of ​​the pattern. On the other hand, in the above manufacturing method, the pattern is formed by processing a film deposited to a uniform thickness, thereby achieving uniform thickness within the pattern, allowing even fine patterns to be used as light-emitting regions in their entirety. Therefore, according to the above manufacturing method, both high resolution and high aperture ratio can be achieved.

[0040] Thus, according to the above manufacturing method, a display device integrating micro-light-emitting elements can be realized without using a special pixel arrangement such as the pentile method to substantially improve the clarity. 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 arranging the so-called stripes of RGB in one direction.

[0041] The following describes a more specific structural example and manufacturing method example of a display device according to an embodiment of the present invention with reference to the drawings.

[0042] [Structural Example 1] FIG1A is a top view schematic diagram of a display device 100 according to an embodiment of the present invention. The display device 100 includes a plurality of light-emitting elements 110R that emit red light, a plurality of light-emitting elements 110G that emit green light, and a plurality of light-emitting elements 110B that emit blue light. In FIG1A, in order to easily distinguish each light-emitting element, the symbols of R, G, and B are shown in the light-emitting area of ​​each light-emitting element.

[0043] Light-emitting elements 110R, 110G, and 110B are all arranged in a matrix. Figure 1A shows a so-called stripe arrangement of light-emitting elements of the same color arranged in one direction. Note that the arrangement of light-emitting elements is not limited to this; delta arrangement, zigzag arrangement, or pentile arrangement can also be used.

[0044] As light-emitting elements 110R, 110G, and 110B, it is preferable to use EL elements such as OLED (Organic Light Emitting Diode) or QLED (Quantum-dot Light Emitting Diode). Examples of light-emitting materials included in the EL element include fluorescent materials (fluorescent materials), phosphorescent materials (phosphorescent materials), materials exhibiting thermally activated delayed fluorescence (thermally activated delayed fluorescence (TADF) materials), or inorganic compounds (quantum dot materials, etc.).

[0045] Figure 1B is a cross-sectional view corresponding to the dashed line A1-A2 in Figure 1A, and Figure 1C is a cross-sectional view corresponding to the dashed line B1-B2.

[0046] Figure 1B shows cross-sections of light-emitting elements 110R, 110G, and 110B. Light-emitting element 110R includes a pixel electrode 111R, an EL layer 112R, and a common electrode 113. Light-emitting element 110G includes a pixel electrode 111G, an EL layer 112G, and a common electrode 113. Light-emitting element 110B includes a pixel electrode 111B, an EL layer 112B, and a common electrode 113.

[0047] The light-emitting element 110R includes an EL layer 112R between the pixel electrode 111R and the common electrode 113. The EL layer 112R contains a light-emitting organic compound that emits light with intensity at least in the red wavelength region. The EL layer 112G included in the light-emitting element 110G contains a light-emitting organic compound that emits light with intensity at least in the green wavelength region. The EL layer 112B included in the light-emitting element 110B contains a light-emitting organic compound that emits light with intensity at least in the blue wavelength region.

[0048] EL layer 112R, EL layer 112G and EL layer 112B may include one or more of the following in addition to the layer containing the luminescent organic compound (luminescent layer): electron injection layer, electron transport layer, hole injection layer and hole transport layer.

[0049] Pixel electrodes 111R, 111G, and 111B are respectively provided in each light-emitting element. Additionally, a common electrode 113 is provided as a continuous layer shared by all light-emitting elements. A conductive film that is transparent to visible light is used as either the pixel electrode or the common electrode 113, while a reflective conductive film is used as the other. By making each pixel electrode transparent and the common electrode 113 reflective, a bottom-emission display device can be realized; conversely, by making each pixel electrode reflective and the common electrode 113 transparent, a top-emission display device can be realized. Furthermore, by making both the pixel electrode and the common electrode 113 transparent, a dual-emission display device can also be realized.

[0050] An insulating layer 131 is provided to cover the ends of pixel electrodes 111R, 111G, and 111B. The ends of the insulating layer 131 are preferably tapered. Note that the insulating layer 131 may be omitted if not required.

[0051] EL layers 112R, EL layers 112G and EL layers 112B each have a region that contacts the top surface of the pixel electrode and a region that contacts the surface of the insulating layer 131. In addition, the ends of EL layers 112R, EL layers 112G and EL layers 112B are located on the insulating layer 131.

[0052] As shown in Figure 1B, a gap is provided between the two EL layers of the light-emitting elements of different colors. Preferably, EL layers 112R, EL layer 112G, and EL layer 112B are disposed without contact with each other. This can appropriately prevent unintentional light emission (also known as crosstalk) caused by current flowing through the two adjacent EL layers. As a result, contrast can be improved, and a display device with higher display quality can be realized.

[0053] Figure 1C shows an example of EL layer 112G being processed into an island shape. Note that, as shown in Figure 1D, EL layer 112G can also be processed into a strip shape in a continuous manner in the column direction. By making EL layer 112G and the like into a strip shape, there is no need to divide the space required for them, and the area of ​​the non-light-emitting region between the light-emitting elements can be reduced, thereby increasing the aperture ratio. Note that Figures 1C and 1D show a cross-section of light-emitting element 110G as an example, but light-emitting elements 110R and 110B can also adopt the same shape.

[0054] 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 water and other impurities from diffusing from above to each light-emitting element.

[0055] The protective layer 121 may, for example, be a single-layer structure or a multilayer structure comprising at least an inorganic insulating film. Examples of inorganic insulating films include 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, and hafnium oxide films. Alternatively, semiconductor materials such as indium gallium oxide and indium gallium zinc oxide may be used as the protective layer 121.

[0056] Alternatively, a laminated film of inorganic and organic insulating films can be used as the protective layer 121. For example, it is preferable to use a structure in which an organic insulating film is sandwiched 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, thereby improving the coverage of the inorganic insulating film thereon and thus improving the barrier properties. In addition, because the top surface of the protective layer 121 is flattened, when a structure (such as a color filter, electrode of a touch sensor, or lens array, etc.) is provided above the protective layer 121, the influence of the uneven shape of the underlying structure can be reduced, which is preferable.

[0057] [Example 1 of Manufacturing Method] An example of a method for manufacturing a display device according to an embodiment of the present invention will be described below with reference to the drawings. Here, the display device 100 shown in the above structural example will be used as an example for description. Figures 2A to 4D are cross-sectional schematic diagrams of each process in the manufacturing method of the display device illustrated below.

[0058] The thin films (insulating films, semiconductor films, conductive films, etc.) constituting the display device can be formed using sputtering, chemical vapor deposition (CVD), vacuum evaporation, pulsed laser deposition (PLD), atomic layer deposition (ALD), and other methods. CVD methods include plasma-enhanced chemical vapor deposition (PECVD) and thermal CVD. Furthermore, as a type of thermal CVD, metal-organic chemical vapor deposition (MOCVD) is also included.

[0059] 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.

[0060] 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, or peeling. Furthermore, island-shaped thin films can be directly formed using a deposition method that utilizes a shadow mask, such as a metal mask.

[0061] 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.

[0062] 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. Extreme ultraviolet (EUV) light or X-rays can also be used as the light for exposure. Furthermore, an electron beam can be used instead of the light used for exposure. When using EUV light, X-rays, or an electron beam, extremely fine processing can be performed, making it preferable. Moreover, when exposure is performed by scanning with a beam such as an electron beam, a photomask is not required.

[0063] As a method for etching thin films, dry etching, wet etching and sandblasting can be used.

[0064] [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.

[0065] 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.

[0066] [Formation of pixel electrodes 111R, 111G, and 111B] Next, a plurality of pixel electrodes 111 are formed on the substrate 101. First, a conductive film to become a pixel electrode is deposited, a photoresist mask is formed by photolithography, and unwanted portions of the conductive film are removed by etching. Then, the photoresist mask is removed, thereby forming pixel electrodes 111R, 111G, and 111B.

[0067] When a conductive film that is reflective to visible light is used as the electrode for each pixel, it is preferable to use a material with the highest possible reflectivity across the entire wavelength range of visible light (e.g., silver or aluminum). This not only improves the light extraction efficiency of the light-emitting element but also enhances color reproduction.

[0068] [Formation of Insulating Layer 131] Next, an insulating layer 131 (FIG. 2A) is formed over the ends of pixel electrodes 111R, 111G, and 111B. An organic or inorganic insulating film can be used as the insulating layer 131. The ends of the insulating layer 131 are preferably tapered to improve the step coverage of the subsequently formed EL film. In particular, when using an organic insulating film, a photosensitive material is preferred, thereby making it easier to control the end shape according to the exposure and development conditions.

[0069] [Formation of EL film 112Rf] Next, an EL film 112Rf, which will become EL layer 112R, is deposited on pixel electrode 111R, pixel electrode 111G, pixel electrode 111B and insulating layer 131 (Fig. 2B).

[0070] The EL film 112Rf includes at least a film containing a luminescent compound. In addition, it may have a structure in which one or more films are stacked and used as an electron injection layer, electron transport layer, charge generation layer, hole transport layer, or hole injection layer. The EL film 112Rf can be formed, for example, by vapor deposition, sputtering, or inkjet printing. Note that this is not a limitation, and the above-described deposition methods can be appropriately utilized.

[0071] [Formation of Sacrificial Film 141a] Next, sacrificial film 141a is formed on EL film 112Rf (Fig. 2C). When forming sacrificial film 141a, wet deposition methods such as spin coating, dip coating, spray coating, inkjet coating, dispenser coating, screen printing, flatbed printing, doctor knife coating, slot coating, roller coating, curtain coating, and blade coating can be appropriately used. Note that other deposition methods can also be used, such as vapor deposition, etc.

[0072] As the sacrificial membrane 141a, it is preferable to use a material that is chemically stable in a solvent, at least for the uppermost layer of the EL membrane 112Rf. In particular, a material soluble in water or alcohol can be suitably used for the sacrificial membrane 141a. When depositing the sacrificial membrane 141a, it is preferable to coat the sacrificial membrane 141a in a solvent such as water or alcohol using the wet deposition method described above, and then perform a heat treatment to evaporate the solvent. At this time, it is preferable to perform the heat treatment under a reduced pressure atmosphere, thereby removing the solvent at a low temperature and for a short time, and reducing the thermal damage to the EL membrane 112Rf.

[0073] As the sacrificial membrane 141a, organic materials such as polyvinyl alcohol (PVA), polyvinyl butyral, polyvinylpyrrolidone, polyethylene glycol, polyglycerol, pullulan, water-soluble cellulose, or alcohol-soluble polyamide resin can be used.

[0074] [Formation of photoresist mask 143a] Next, a photoresist mask 143a is formed on the sacrificial film 141a and in the region overlapping the pixel electrode 111R (FIG. 2D). The photoresist mask 143a is preferably made of an organic resin material that can be etched under the same etching conditions as the sacrificial film 141a.

[0075] The photoresist mask 143a may be a photoresist material containing a photosensitive resin, such as a positive photoresist material or a negative photoresist material.

[0076] [Etching of sacrificial film 141a, photoresist mask 143a, and EL film 112Rf] Next, the sacrificial film 141a, photoresist mask 143a, and EL film 112Rf are etched, thereby exposing a portion of the top surface of the insulating layer 131, the top surface of the pixel electrode 111G, and the top surface of the pixel electrode 111B (FIG. 2E). This allows the formation of an island-shaped or strip-shaped EL layer 112R and a sacrificial layer 142a on the EL layer 112R.

[0077] Etching is preferably performed under conditions that allow etching of the sacrificial film 141a, the photoresist mask 143a, and the EL film 112Rf. In particular, when using anisotropic dry etching, it is preferable to prevent the exposed sides of the EL layer 112R from being etched, thus preventing the pattern of the EL layer 112R from shrinking after etching.

[0078] In addition, each of the sacrificial film 141a, the photoresist mask 143a and the EL film 112Rf can be etched separately, or any two of them can be etched in the same process. For example, the sacrificial film 141a can be etched first, and then the photoresist mask 143a and the EL film 112Rf can be etched in the same process.

[0079] Preferably, the sacrificial layer 142a remains on the EL layer 112R at the end of the etching process. Thus, the sacrificial layer 142a can be used as a protective layer to protect the EL layer 112R from damage in subsequent processes.

[0080] [Formation of EL film 112Gf] Next, an EL film 112Gf, which will become EL layer 112G, is deposited on the sacrificial layer 142a, the insulating layer 131, the pixel electrode 111G and the pixel electrode 111B (Fig. 3A).

[0081] The method for forming the EL film 112Gf can be referred to the description of the EL film 112Rf above.

[0082] [Formation of sacrificial membrane 141b] Next, sacrificial membrane 141b is formed on EL membrane 112Gf. Sacrificial membrane 141b can be formed in the same way as sacrificial membrane 141a described above. In particular, sacrificial membrane 141b is preferably made of the same material as sacrificial membrane 141a.

[0083] [Formation of photoresist mask 143b] Next, a photoresist mask 143b is formed on the sacrificial film 141b (FIG. 3B). The photoresist mask 143b is formed in the region overlapping the pixel electrode 111G and the region overlapping the pixel electrode 111R, respectively.

[0084] The method for forming the photoresist mask 143b can refer to the description of the photoresist mask 143a above.

[0085] [Etching of sacrificial film 141b, photoresist mask 143b and EL film 112Gf] Next, the sacrificial film 141b, photoresist mask 143b and EL film 112Gf are etched, thereby exposing a portion of the top surface of the insulating layer 131 and the top surface of the pixel electrode 111B (FIG. 3C). This allows the formation of an island-shaped or strip-shaped EL layer 112G and sacrificial layer 142b.

[0086] Etching is preferably performed under conditions that allow etching of the sacrificial film 141b, the photoresist mask 143b, and the EL film 112Gf. For example, when etching them using anisotropic dry etching, the sacrificial film 141b on top of the pixel electrode 111B, which is not covered by the photoresist mask 143b, disappears first compared to the portion covered by the photoresist mask 143b, thereby leaving the sacrificial layer 142b.

[0087] In addition, when etching is performed in a one-time etching process, the process is completed at the point when the etching of the EL film 112Gf ends, as shown in FIG3C, so that the sacrificial layer 142a on the EL layer 112R can remain and not disappear.

[0088] [Formation of EL film 112Bf] Next, an EL film 112Bf, which will become EL layer 112B, is deposited on sacrificial layer 142a, sacrificial layer 142b, pixel electrode 111B and insulating layer 131 (Fig. 3D).

[0089] The method for forming EL film 112Bf can be referred to the description of EL film 112Rf above.

[0090] [Formation of sacrificial membrane 141c] Next, sacrificial membrane 141c is formed on EL membrane 112Bf. Sacrificial membrane 141c can be formed in the same way as sacrificial membrane 141a described above. In particular, sacrificial membrane 141c is preferably made of the same material as sacrificial membranes 141a and 141b.

[0091] [Formation of photoresist mask 143c] Next, a photoresist mask 143c is formed on the sacrificial film 141c (FIG. 4A). The photoresist mask 143c is formed in the regions overlapping the pixel electrode 111B, the regions overlapping the pixel electrode 111R, and the regions overlapping the pixel electrode 111G.

[0092] The method for forming the photoresist mask 143c can refer to the description of the photoresist mask 143a above.

[0093] [Etching of sacrificial film 141c, photoresist mask 143c and EL film 112Bf] Next, the sacrificial film 141c, photoresist mask 143c and EL film 112Bf are etched, thereby exposing a portion of the top surface of the insulating layer 131 (FIG. 4B). This allows the formation of an island-shaped or strip-shaped EL layer 112B and sacrificial layer 142c.

[0094] The etching can be described with reference to the above description of the etching of the sacrificial film 141b, etc. By etching, the sacrificial layer 142a on the EL layer 112R and the sacrificial layer 142b on the EL layer 112G can remain and not disappear.

[0095] [Removal of sacrificial layers] Next, sacrificial layers 142a, 142b and 142c are removed to expose the top surfaces of EL layers 112R, 112G and 112B respectively (Fig. 4C).

[0096] The sacrificial layers 142a, 142b and 142c can be removed by wet etching or dry etching. In this case, it is preferable to use a method that minimizes damage to the EL layers 112R, EL layers 112G and EL layers 112B.

[0097] In particular, it is preferable to remove the sacrificial layers 142a, 142b and 142c by dissolving them in a solvent such as water or alcohol.

[0098] Here, various alcohols such as ethanol, methanol, isopropanol (IPA) or glycerol can be used as alcohols that can dissolve sacrificial layers 142a, 142b and 142c.

[0099] To remove water contained within EL layers 112R, EL layers 112G, and EL layers 112B, and water adsorbed on the surface, after removing sacrificial layers 142a, 142b, and 142c, a drying process is preferably performed. For example, a heating process is preferably performed under an inert gas atmosphere or a reduced pressure atmosphere. The heating process can be performed at a substrate temperature of 50°C or higher and 200°C or lower, preferably 60°C or higher and 150°C or lower, and more preferably 70°C or higher and 120°C or lower. Using a reduced pressure atmosphere allows drying to be performed at a lower temperature, which is therefore preferable.

[0100] Through the above process, three types of EL layers can be formed respectively.

[0101] [Formation of common electrode 113] Next, a common electrode 113 is formed by covering EL layer 112R, EL layer 112G and EL layer 112B (FIG. 4D). The common electrode 113 can be formed, for example, by sputtering or vapor deposition.

[0102] The above process can be used to manufacture light-emitting element 110R, light-emitting element 110G and light-emitting element 110B.

[0103] [Formation of Protective Layer 121] Next, a protective layer 121 is formed on the common electrode 113 (FIG. 4E). The inorganic insulating film used for the protective layer 121 is preferably deposited using sputtering, PECVD, or ALD. ALD is particularly preferred because it provides excellent step coverage and is less prone to defects such as pinholes. Alternatively, the organic insulating film is preferably deposited using inkjet printing, thereby forming a uniform film in the desired area.

[0104] The above is an explanation of an example of a manufacturing method for a display device.

[0105] [Structural Example 2] The following describes a structural example of a display device that differs from Structural Example 1 described above. Additionally, descriptions that overlap with the above descriptions may be omitted in the following.

[0106] [Structural Example 2-1] The main difference between the display device 100A shown in Figure 5A and the display device 100 described above is that it includes a common layer 114.

[0107] Similar to the common electrode 113, the common layer 114 is disposed across multiple light-emitting elements. The common layer 114 is disposed in a manner that covers the EL layers 112R, EL layers 112G, and EL layers 112B. By adopting a structure including the common layer 114, the manufacturing process can be simplified and manufacturing costs can be reduced.

[0108] For example, preferably, EL layer 112R, EL layer 112G, and EL layer 112B each include at least one light-emitting layer containing a light-emitting material that emits light of one color. Additionally, for example, the common layer 114 is preferably a layer including one or more of an electron injection layer, an electron transport layer, a hole injection layer, and a hole transport layer. For example, in a light-emitting element where the pixel electrode and the common electrode are the anode and cathode, respectively, the common layer 114 may employ a structure including an electron injection layer or a structure including both an electron injection layer and an electron transport layer.

[0109] [Structural Example 2-2] The main difference between the display device 100B shown in Figure 5B and the display device 100A described above is the structure of the light-emitting element.

[0110] The light-emitting element 110R includes an optical adjustment layer 115R between the pixel electrode 111R and the EL layer 112R. The light-emitting element 110G includes an optical adjustment layer 115G between the pixel electrode 111G and the EL layer 112G. The light-emitting element 110B includes an optical adjustment layer 115B between the pixel electrode 111B and the EL layer 112B.

[0111] Furthermore, optical adjustment layers 115R, 115G, and 115B are all transparent to visible light. The thicknesses of optical adjustment layers 115R, 115G, and 115B are all different. This allows for different optical path lengths between the various light-emitting elements.

[0112] Here, a conductive film that is reflective to visible light is used as pixel electrode 111R, pixel electrode 111G, and pixel electrode 111B, and a conductive film that is both reflective and transmissive to visible light is used as the common electrode 113. Thus, each light-emitting element realizes a so-called microcavity structure (micro-resonator structure), enhancing light of a specific wavelength. Therefore, a display device with improved color purity can be realized.

[0113] As each optical adjustment layer, a conductive material that is transparent to visible light can be used. For example, conductive oxides such as indium oxide, indium tin oxide, indium zinc oxide, zinc oxide, gallium-containing zinc oxide, silicon-containing indium tin oxide, and silicon-containing indium zinc oxide can be used.

[0114] Each optical adjustment layer can be formed after the formation of pixel electrode 111R, pixel electrode 111G and pixel electrode 111B and before the formation of EL film 112Rf, etc. Each optical adjustment layer can use conductive films of different thicknesses, or can adopt a single-layer structure, two-layer structure, three-layer structure, etc., in ascending order of the thickness of each optical adjustment layer.

[0115] [Structural Examples 2-3] The main difference between the display device 100C shown in Figure 5C and the display device 100B described above is that it does not include an optical adjustment layer.

[0116] The display device 100C is an example of realizing a microcavity structure by utilizing the thickness of the EL layer 112R, EL layer 112G and EL layer 112B. By adopting this structure, there is no need to set up an optical adjustment layer, so the manufacturing process can be simplified.

[0117] For example, in the display device 100C, the EL layer 112R of the light-emitting element 110R that emits the longest wavelength light is the thickest, and the EL layer 112B of the light-emitting element 110B that emits the shortest wavelength light is the thinnest. Note that this is not a limitation, and the thickness of each EL layer can be adjusted by taking into account the wavelength of 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.

[0118] In addition, Figures 5B and 5C show examples including the common layer 114, but a structure that does not include the common layer 114 can also be used.

[0119] [Manufacturing Method Example 2] The following describes an example of a manufacturing method for a display device that differs from the manufacturing method example 1 described above. Note that sometimes, descriptions of parts that are repeated above are omitted with reference to that section.

[0120] First, similar to the manufacturing method example 1 described above, pixel electrodes 111R, 111G, 111B, and an insulating layer 131 are formed on the substrate 101. Then, an EL film 112Rf is formed over them.

[0121] [Formation of sacrificial membrane 144a] Next, sacrificial membrane 144a is formed by covering EL membrane 112Rf.

[0122] The sacrificial film 144a can be a film with high resistance to etching of various EL films such as the EL film 112Rf, that is, a film with a high etching rate. In addition, the sacrificial film 144a can be a film with a high etching rate compared to the protective film such as the protective film 146a described later. Furthermore, the sacrificial film 144a can be a film that can be removed by wet etching with minimal damage to each EL film.

[0123] As the sacrificial membrane 144a, inorganic membranes such as metal membranes, alloy membranes, metal oxide membranes, semiconductor membranes, and inorganic insulating membranes can be used. Alternatively, organic membranes such as polyvinyl alcohol, which can be used for sacrificial membranes 141a, as illustrated in Example 1 of the manufacturing method, can also be used.

[0124] 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. Low-melting-point materials such as aluminum or silver are particularly preferred.

[0125] Additionally, indium gallium zinc oxide (In-Ga-Zn oxide, also denoted as IGZO) or other metal oxides can be used as the sacrificial film 144a. Furthermore, indium oxide, indium zinc oxide (In-Zn oxide), indium tin oxide (In-Sn oxide), indium titanium oxide (In-Ti oxide), indium tin zinc oxide (In-Sn-Zn oxide), indium titanium zinc oxide (In-Ti-Zn oxide), indium gallium tin zinc oxide (In-Ga-Sn-Zn oxide), etc., can be used. Alternatively, indium tin oxide containing silicon, etc., can also be used.

[0126] Note that element M (selected from 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) may be used instead of gallium. In particular, M is preferably selected from one or more of gallium, aluminum, and yttrium.

[0127] In addition, inorganic insulating materials such as alumina, hafnium oxide, and silicon oxide can be used as sacrificial membrane 144a.

[0128] [Formation of protective film 146a] Next, protective film 146a is formed on sacrificial film 144a.

[0129] The protective film 146a is used as a hard mask when the sacrificial film 144a is subsequently etched. Furthermore, the sacrificial film 144a is exposed during the subsequent processing of the protective film 146a. Therefore, a combination of films with a high etch rate is selected as the sacrificial film 144a and the protective film 146a. Thus, a film suitable for use as the protective film 146a can be selected based on the etching conditions of both the sacrificial film 144a and the protective film 146a.

[0130] For example, when the etching of the protective film 146a is performed using dry etching with a fluorine-containing gas (also known as a fluorine-based gas), 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 for the protective film 146a. Here, as a film with a high etching rate (in other words, a slow etching rate) relative to the aforementioned dry etching using fluorine-based gases, metal oxide films such as IGZO and ITO can be used, and such films can be used for the sacrificial film 144a.

[0131] Note that, not limited thereto, the protective film 146a may be selected from various materials depending on the etching conditions of the sacrificial film 144a and the etching conditions of the protective film 146a. For example, it may also be selected from films that can be used for the sacrificial film 144a described above.

[0132] In addition, as a protective film 146a, a nitride film can be used, for example. Specifically, silicon nitride, aluminum nitride, hafnium nitride, titanium nitride, tantalum nitride, tungsten nitride, gallium nitride, germanium nitride, and other nitrides can also be used.

[0133] Furthermore, an organic membrane suitable for use with EL membrane 112Rf, etc., can also be used as the protective membrane 146a. For example, the same organic membrane used for EL membrane 112Rf, EL membrane 112Gf, or EL membrane 112Bf can be used as the protective membrane 146a. By using such an organic membrane, the deposition apparatus can be used together with the EL membrane 112Rf, etc., which is preferable.

[0134] [Forming of photoresist mask 143a] Next, a photoresist mask 143a is formed on the protective film 146a and at a position overlapping the pixel electrode 111R (Fig. 6A).

[0135] Here, when a photoresist mask 143a is formed on the sacrificial film 144a without a protective film 146a, if there are defects such as pinholes in the sacrificial film 144a, the EL film 112Rf may dissolve due to the solvent of the photoresist material. By using the protective film 146a, this defect can be prevented.

[0136] [Etching of protective film 146a] Next, a portion of the protective film 146a that is not covered by the photoresist mask 143a is removed by etching to form an island-shaped or strip-shaped protective layer 147a.

[0137] When etching the protective film 146a, it is preferable to use etching conditions with a high selectivity to prevent the sacrificial film 144a from being removed by the etching. The etching of the protective film 146a can be performed by wet etching or dry etching, but by using dry etching, the pattern shrinkage of the protective film 146a can be suppressed.

[0138] [Removal of photoresist mask 143a] Next, remove photoresist mask 143a (Fig. 6B).

[0139] The removal of the photoresist mask 143a can be performed by wet etching or dry etching. It is particularly preferred that the photoresist mask 143a be removed by dry etching (also known as plasma ashing) using oxygen gas as the etching gas.

[0140] At this time, since the removal of the photoresist mask 143a is performed while the EL film 112Rf is covered by the sacrificial film 144a, the influence on the EL film 112Rf is suppressed. In particular, when the EL film 112Rf is exposed to oxygen, it sometimes has a negative impact on the electrical properties, so this is preferable when performing etching using oxygen gas, such as plasma ashing.

[0141] [Etching of sacrificial film 144a] Next, the protective layer 147a is used as a mask and the portion of the sacrificial film 144a not covered by the protective layer 147a is removed by etching to form an island-shaped or strip-shaped sacrificial layer 145a (Fig. 6C).

[0142] The etching of the sacrificial film 144a can be performed by wet etching or dry etching, but dry etching is preferred, thereby suppressing the shrinkage of the pattern.

[0143] [Etching of EL film 112Rf and protective layer 147a] Next, while etching the protective layer 147a, a portion of the EL film 112Rf not covered by the sacrificial layer 145a is removed by etching to form an island-shaped or strip-shaped EL layer 112R (Fig. 6D).

[0144] By etching the EL film 112Rf and the protective layer 147a in the same process, the process can be simplified and the manufacturing cost of the display device can be reduced.

[0145] In particular, the etching of the EL film 112Rf is preferably performed by dry etching using an etching gas whose main component does not contain oxygen. This suppresses deterioration of the EL film 112Rf, enabling a display device with high reliability. Examples of etching gases whose main component does not contain oxygen include rare gases such as CF4, C4F8, SF6, CHF3, Cl2, H2O, BCl3, or He. Alternatively, a mixture of the above gases and an oxygen-free diluent gas can be used as the etching gas.

[0146] Alternatively, the EL film 112Rf and the protective layer 147a can be etched separately. In this case, the EL film 112Rf can be etched first, or the protective layer 147a can be etched first.

[0147] [Formation of EL layer 112G and EL layer 112B] By performing the above process on EL film 112Gf, island-shaped EL layer 112G and sacrificial layer 145b can be formed.

[0148] That is, after forming the EL layer 112R, the EL film 112Gf, sacrificial film 144b, protective film 146b, and photoresist mask 143b are formed sequentially as shown in FIG7A. Next, the protective film 146b is etched to form a protective layer 147b, and then the photoresist mask 143b is removed (FIG7B). Next, the sacrificial film 144b is etched to form a sacrificial layer 145b. Then, the protective layer 147b and the EL film 112Gf are etched to form an island-shaped or strip-shaped EL layer 112G (FIG7C).

[0149] Next, the same process as described above is performed on the EL film 112Bf, thereby forming an island-shaped EL layer 112B and a sacrificial layer 145c (Fig. 7D).

[0150] [Removal of sacrificial layers] Next, sacrificial layers 145a, 145b and 145c are removed to expose the top surfaces of EL layers 112R, 112G and 112B respectively (Fig. 7E).

[0151] Sacrificial layers 145a, 145b, and 145c can be removed by wet etching or dry etching. In this case, it is preferable to use a method that causes as little damage as possible to EL layers 112R, EL layers 112G, and EL layers 112B. Wet etching is particularly preferred. For example, wet etching using an aqueous solution of tetramethylammonium hydroxide (TMAH), dilute hydrofluoric acid, oxalic acid, phosphoric acid, acetic acid, nitric acid, or a mixture thereof is preferred.

[0152] Thus, EL layer 112R, EL layer 112G and EL layer 112B can be formed respectively. For further details, please refer to manufacturing method example 1.

[0153] The above is an explanation of manufacturing method example 2.

[0154] By using the above manufacturing method, process damage to EL layer 112R, EL layer 112G and EL layer 112B can be reduced, thereby achieving a display device with extremely high reliability.

[0155] [Structural Example 3] The following describes an example of using a light-emitting element that emits white light.

[0156] Figures 8A and 8B are cross-sectional schematic diagrams of the display device 150. Its top view can be seen in Figure 1A.

[0157] The display device 150 includes a light-emitting unit 120R, a light-emitting unit 120G, and a light-emitting unit 120B. Each of the light-emitting units 120R, 120G, and 120B includes a light-emitting element 110W. The light-emitting element 110W includes a pixel electrode 111, an EL layer 112W, and a common electrode 113. The common electrode 113 is disposed across multiple pixels. The EL layer 112W includes a light-emitting layer that emits white light. The light-emitting element 110W is a light-emitting element that emits white light.

[0158] Furthermore, the light-emitting units 120R, 120G, and 120B each include a color layer 122R, a color layer 122G, or a color layer 122B on the protective layer 121. For example, color layer 122R transmits red light, color layer 122G transmits green light, and color layer 122B transmits blue light. This allows for a full-color display device. Additionally, compared to bonding two substrates after forming color layers on a substrate different from substrate 101, forming each color layer on the protective layer 121 makes it easier to align the light-emitting elements and color layers, thus enabling a display device with extremely high resolution.

[0159] Here, the EL layer 112W is divided between different light-emitting units. This can appropriately prevent unintentional light emission (crosstalk) caused by current flowing through the EL layer 112W between adjacent light-emitting units. As a result, the contrast ratio can be improved, and a display device with higher display quality can be realized.

[0160] Note that, as shown in Figure 8B, a structure in which the EL layer 112W is not separated between light-emitting units of the same color can also be adopted.

[0161] [Manufacturing Method Example 3] The following describes an example of a manufacturing method for the display device 150 illustrated in the above structural example 3. Note that sometimes, descriptions of parts that are repeated with manufacturing methods 1 and 2 described above are omitted with reference to this section.

[0162] First, as shown in FIG9A, a plurality of pixel electrodes 111 and an insulating layer 131 are formed on the substrate 101. Then, an EL film 112Wf, a sacrificial film 144 and a protective film 146 are formed over them. Furthermore, a photoresist mask 143 is formed on the protective film 146 and at a position overlapping the pixel electrodes 111.

[0163] Next, the protective film 146 is etched to form a strip-shaped protective layer 147 (Fig. 9B).

[0164] Next, the photoresist mask 143 is removed, and the protective layer 147 is used as a mask to etch the sacrificial film 144 to form the sacrificial layer 145 (FIG. 9C).

[0165] Next, the protective layer 147 and the EL film 112Wf are etched to separate the EL film 112Wf. As a result, a plurality of strip-shaped EL layers 112W are formed (FIG. 9D). Then, the sacrificial layer 145 on the EL layer 112 is removed to expose the EL layer 112W (FIG. 9E).

[0166] Next, a common electrode 113 is formed by covering the EL layer 112W and the insulating layer 131, thereby enabling the fabrication of multiple light-emitting elements 110W (Fig. 9F).

[0167] Next, a protective layer 121 is formed over the common electrode 113, and color layers 122R, 122G, and 122B are formed on the protective layer 121. Color layers 122R, 122G, and 122B can all be formed using photolithography with photosensitive resin.

[0168] Thus, the display device 150 illustrated in the above structural example 3 can be manufactured.

[0169] At least a portion of this embodiment may be implemented in combination with other embodiments described in this specification.

[0170] 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.

[0171] 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.

[0172] [Display Device 400A] FIG10 shows a perspective view of display device 400A, and FIG11A shows a cross-sectional view of display device 400A.

[0173] The display device 400A has a structure that attaches a substrate 452 and a substrate 451. In FIG10, the substrate 452 is indicated by a dashed line.

[0174] The display device 400A includes a display unit 462, a circuit 464, and wiring 465, etc. Figure 10 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 10 can also be referred to as a display module including the display device 400A, an IC (integrated circuit), and an FPC.

[0175] As circuit 464, for example, a scan line drive circuit can be used.

[0176] 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.

[0177] Figure 10 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.

[0178] FIG11A shows an example of a cross-section of a portion of the area including the FPC 472, a portion of the circuit 464, a portion of the display portion 462, and a portion of the area including the end of the display device 400A.

[0179] The display device 400A shown in FIG11A includes transistors 201 and 205, light-emitting elements 430a emitting red light, light-emitting elements 430b emitting green light, and light-emitting elements 430c emitting blue light between substrates 451 and 452.

[0180] The light-emitting elements 430a, 430b and 430c can be the light-emitting elements illustrated in Embodiment 1.

[0181] Here, when the pixels of the display device include three sub-pixels having light-emitting elements that emit different colors from each other, examples of the three sub-pixels are sub-pixels of colors R, G, and B, and sub-pixels of 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 colors R, G, B, and white (W), and sub-pixels of colors R, G, B, and Y.

[0182] The protective layer 416 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 11A, 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.

[0183] Light-emitting elements 430a, 430b, and 430c include an optical adjustment layer between the pixel electrode and the EL layer. Light-emitting element 430a includes an optical adjustment layer 426a, light-emitting element 430b includes an optical adjustment layer 426b, and light-emitting element 430c includes an optical adjustment layer 426c. For details of the light-emitting elements, please refer to Embodiment 1.

[0184] Pixel electrodes 411a, 411b, and 411c are connected to the conductive layer 222b of the transistor 205 through openings provided in the insulating layer 214.

[0185] The ends of the pixel electrode and the optical adjustment layer are covered by an insulating layer 421. The pixel electrode contains a material that emits visible light, and the common electrode contains a material that transmits visible light.

[0186] 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.

[0187] Transistors 201 and 205 are both disposed on substrate 451. These transistors can be formed using the same material and the same process.

[0188] 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.

[0189] 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.

[0190] 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.

[0191] 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.

[0192] 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 resins, polyimide resins, epoxy resins, polyimide resins, polyimide-polyimide resins, silicone resins, benzocyclobutene resins, phenolic resins, and precursors of these resins.

[0193] In region 228 shown in FIG11A, an opening is formed in the insulating layer 214. Therefore, even when an organic insulating film is used as the insulating layer 214, impurities can be prevented from entering the display section 462 from the outside through the insulating layer 214. This improves the reliability of the display device 400A.

[0194] Transistors 201 and 205 include: a conductive layer 221 serving as a gate; an insulating layer 211 serving as a gate insulating layer; conductive layers 222a and 222b serving as a source and drain, respectively; a semiconductor layer 231; an insulating layer 213 serving as a gate insulating layer; and a conductive layer 223 serving as a gate. Here, multiple layers obtained by processing the same conductive film are represented by the same shaded line. The insulating layer 211 is located between the conductive layer 221 and the semiconductor layer 231. The insulating layer 213 is located between the conductive layer 223 and the semiconductor layer 231.

[0195] 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 can be used. Furthermore, the transistor can have a top-gate structure or a bottom-gate structure. Alternatively, gates can be provided above and below the semiconductor layer forming the channel.

[0196] 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.

[0197] There are no particular restrictions on the crystallinity of the semiconductor material used for the transistor. Amorphous semiconductors, single-crystal semiconductors, or crystalline semiconductors other than single-crystal semiconductors (microcrystalline semiconductors, polycrystalline semiconductors, or semiconductors with crystalline regions in part) can be used. When using single-crystal semiconductors or crystalline semiconductors, the degradation of transistor characteristics can be suppressed, so it is preferable.

[0198] The semiconductor layer of the transistor preferably comprises a metal oxide (oxide semiconductor). That is, the display device of this embodiment preferably uses a transistor (hereinafter, OS transistor) in which a metal oxide is used in the channel forming region. In addition, the semiconductor layer of the transistor may also comprise silicon. Examples of silicon include amorphous silicon, crystalline silicon (low-temperature polycrystalline silicon, monocrystalline silicon, etc.).

[0199] For example, the semiconductor layer preferably comprises indium, M (M is selected from one or more of gallium, aluminum, silicon, boron, yttrium, tin, copper, vanadium, beryllium, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, or magnesium), and zinc. In particular, M is preferably selected from one or more of aluminum, gallium, yttrium, or tin.

[0200] In particular, as a semiconductor layer, it is preferable to use an oxide (IGZO) containing indium (In), gallium (Ga) and zinc (Zn).

[0201] When using In-M-Zn oxide in a semiconductor layer, the number of In atoms in the In-M-Zn oxide is preferably greater than or equal to the number of M atoms. Examples of atomic ratios of the metal elements in this 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 = 2:1:3 or similar, In:M:Zn = 3:1:2 or similar, In:M:Zn = 4:2:3 or similar, 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, "similar" composition includes a range of ±30% of the desired atomic ratio.

[0202] For example, when the atomic number ratio is described as In:Ga:Zn = 4:2:3 or a similar composition, the following cases are included: when the atomic number ratio of In is 4, the atomic number ratio of Ga is 1 or more and 3 or less, and the atomic number ratio of 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 a similar composition, the following cases are included: when the atomic number ratio of In is 5, the atomic number ratio of Ga is greater than 0.1 and less than 2, and the atomic number ratio of Zn is 5 or more and less than 7. Furthermore, when the atomic number ratio is described as In:Ga:Zn = 1:1:1 or a similar composition, the following cases are included: when the atomic number ratio of In is 1, the atomic number ratio of Ga is greater than 0.1 and less than 2, and the atomic number ratio of Zn is greater than 0.1 and less than 2.

[0203] 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.

[0204] A connection portion 204 is provided in a region where the substrates 451 and 452 do not overlap. 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 has a stacked structure of a conductive film processed with the same conductive film as the pixel electrode and a conductive film processed with 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.

[0205] 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. As optical components, polarizing plates, retardation plates, light diffusion layers (diffusion films, etc.), anti-reflective layers, and condensing films can be used. In addition, 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.

[0206] By forming a protective layer 416 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.

[0207] In the region 228 near the end of the display device 400A, it is preferable that the insulating layer 215 and the protective layer 416 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 416 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.

[0208] FIG11B shows an example of a protective layer 416 having a three-layer structure. In FIG11B, the protective layer 416 includes an inorganic insulating layer 416a on the light-emitting element 430c, an organic insulating layer 416b on the inorganic insulating layer 416a, and an inorganic insulating layer 416c on the organic insulating layer 416b.

[0209] The ends of the inorganic insulating layer 416a and the inorganic insulating layer 416c extend to the outside of the end of the organic insulating layer 416b, and they are in contact with each other. Furthermore, the inorganic insulating layer 416a contacts the insulating layer 215 (inorganic insulating layer) through an opening in the insulating layer 214 (organic insulating layer). Thus, the light-emitting element can be surrounded by the insulating layer 215 and the protective layer 416, improving the reliability of the light-emitting element.

[0210] Thus, the protective layer 416 may also have a laminated structure of an organic insulating film and an inorganic insulating film. In this case, the end of the inorganic insulating film preferably extends to the outside of the end of the organic insulating film.

[0211] 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 emitted from the light-emitting element uses a material that allows the light to pass through. By using a flexible material for substrates 451 and 452, the flexibility of the display device can be improved. A polarizing plate can be used as substrate 451 or substrate 452.

[0212] 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. Alternatively, glass with a flexible thickness can be used as one or both of substrates 451 and 452.

[0213] 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).

[0214] 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.

[0215] As thin films with high optical isotropy, examples include cellulose triacetate (also known as TAC, Cellulose triacetate) films, cyclic olefin polymer (COP) films, cyclic olefin copolymer (COC) films, and acrylic films.

[0216] 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.

[0217] 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.

[0218] As the connecting layer 242, anisotropic conductive film (ACF) or anisotropic conductive paste (ACP) can be used.

[0219] 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.

[0220] 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 materials 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).

[0221] 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.

[0222] [Display Device 400B] FIG12A shows a cross-sectional view of display device 400B. The perspective view of display device 400B is the same as that of display device 400A (FIG. 10). FIG12A shows an example of a cross-section of display device 400B including a portion of the area of ​​FPC 472, a portion of circuit 464, and a portion of display unit 462. FIG12A shows an example of a cross-section of display unit 462 including a light-emitting element 430b emitting green light and a light-emitting element 430c emitting blue light. Note that descriptions of parts identical to those in display device 400A are sometimes omitted.

[0223] The display device 400B shown in FIG12A includes transistors 202, transistors 210, light-emitting elements 430b and 430c between substrates 453 and 454.

[0224] Furthermore, the substrate 454 and the protective layer 416 are bonded together by the adhesive layer 442. The adhesive layer 442 overlaps with the light-emitting element 430b and the light-emitting element 430c respectively, and the display device 400B adopts a solid sealing structure.

[0225] The substrate 453 and the insulating layer 212 are bonded together by the adhesive layer 455.

[0226] The manufacturing method of the display device 400B is as follows: First, a manufacturing substrate having an insulating layer 212, transistors, light-emitting devices, etc., disposed on it is bonded together with a substrate 454 having a light-shielding layer 417 disposed on it using an adhesive layer 442; then, a substrate 453 is bonded to the surface exposed after peeling off the manufacturing substrate, thereby transferring the components formed on the manufacturing substrate to the substrate 453. The substrates 453 and 454 are preferably flexible. This improves the flexibility of the display device 400B.

[0227] As the insulating layer 212, an inorganic insulating film that can be used for insulating layers 211, 213 and 215 can be used.

[0228] The pixel electrode is electrically connected to the conductive layer 222b included in the transistor 210 through an opening provided in the insulating layer 214. The conductive layer 222b is connected to the low-resistance region 231n through openings provided in the insulating layers 215 and 225. The transistor 210 has the function of controlling the driving of the light-emitting element.

[0229] The end of the pixel electrode is covered by an insulating layer 421.

[0230] Light-emitting elements 430b and 430c emit light onto one side of substrate 454. Substrate 454 is preferably made of a material with high transmittance to visible light.

[0231] A connection portion 204 is provided in a region where substrates 453 and 454 do not overlap. In the connection portion 204, wiring 465 is electrically connected to FPC 472 via conductive layer 466 and connection layer 242. Conductive layer 466 can be obtained by processing a conductive film identical to that of the pixel electrode. Therefore, the connection portion 204 can be electrically connected to FPC 472 via connection layer 242.

[0232] Transistors 202 and 210 include: a conductive layer 221 serving as a gate; an insulating layer 211 serving as a gate insulating layer; a semiconductor layer 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 225 serving as a gate insulating layer; a conductive layer 223 serving as a gate; and an insulating layer 215 covering the conductive layer 223. The insulating layer 211 is located between the conductive layer 221 and the channel forming region 231i. The insulating layer 225 is located between the conductive layer 223 and the channel forming region 231i.

[0233] Conductive layers 222a and 222b are connected to the low-resistance region 231n through openings provided in the insulating layer 215. One of the conductive layers 222a and 222b is used as a source and the other is used as a drain.

[0234] Figure 12A shows an example of insulating layer 225 covering the top and side surfaces of semiconductor layer. Conductive layers 222a and 222b are connected to low-resistance region 231n through openings provided in insulating layer 225 and insulating layer 215.

[0235] On the other hand, in the transistor 209 shown in FIG12B, the insulating layer 225 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 FIG12B can be formed by processing the insulating layer 225 with the conductive layer 223 as a mask. In FIG12B, the insulating layer 215 covers the insulating layer 225 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.

[0236] 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.

[0237] Embodiment 3 In this embodiment, an example of a display device structure that is different from the above will be described.

[0238] 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.

[0239] [Display Module] FIG13A 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 or display device 400E, which will be described later.

[0240] 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 display light from each pixel disposed in the pixel section 284 described below.

[0241] FIG13B 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.

[0242] 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 FIG13B. Pixel 284a includes light-emitting elements 430a, 430b, and 430c that emit different colors from each other. The plurality of light-emitting elements can also be configured in a delta arrangement as shown in FIG13B. A delta arrangement allows for a high-density arrangement of pixel circuits, thereby providing a high-definition display device. In addition, various arrangement methods such as stripe arrangement and pentile arrangement can be used.

[0243] The pixel circuit section 283 includes a plurality of pixel circuits 283a arranged periodically.

[0244] A pixel circuit 283a controls the light emission of the three light-emitting elements included in a pixel 284a. A pixel circuit 283a can be composed of three circuits that control the light emission of one light-emitting element. For example, the pixel circuit 283a can adopt 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. Thus, an active matrix display device is realized.

[0245] The circuit section 282 includes circuitry for driving each pixel circuit 283a of the 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.

[0246] 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.

[0247] 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%, and 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 preferably has pixels 284a arranged with a resolution of 2000 ppi or more, more preferably 3000 ppi or more, further preferably 5000 ppi or more, and even more preferably 6000 ppi or more and less than 20000 ppi or less than 30000 ppi.

[0248] This high-definition display module 280 is suitable for use in VR devices such as head-mounted displays or glasses-type AR devices. For example, even when the high-definition display module 280 is used in a device that views the display through a lens, the pixels of the display, magnified by the lens, are not easily seen by the user, thus enabling a highly immersive display because the display 281 in the display module 280 has extremely high resolution. Furthermore, the display module 280 can also be applied to electronic devices with relatively small display units. For example, it is suitable for use in the display units of wearable electronic devices such as watch-type devices.

[0249] [Display Device 400C] The display device 400C shown in FIG14 includes a substrate 301, light-emitting elements 430a, 430b, 430c, a capacitor 240, and a transistor 310.

[0250] The substrate 301 corresponds to the substrate 291 in FIG13A and FIG13B. The stacked structure 401 from the substrate 301 to the insulating layer 255 corresponds to the substrate 101 in Embodiment 1.

[0251] 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 side of conductive layer 311 and serves as an insulating layer.

[0252] Furthermore, a component separation layer 315 is provided between two adjacent transistors 310 in such a way as to be embedded in the substrate 301.

[0253] 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.

[0254] 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 in the capacitor 240, the conductive layer 245 serves as the other electrode in the capacitor 240, and the insulating layer 243 serves as the dielectric of the capacitor 240.

[0255] 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.

[0256] 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 416 is provided on the light-emitting elements 430a, 430b, 430c, and a substrate 420 is attached to the top surface of the protective layer 416 through a resin layer 419. The substrate 420 corresponds to the substrate 292 in Figures 13A and 13B.

[0257] 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.

[0258] [Display Device 400D] The main difference between the display device 400D shown in Figure 15 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.

[0259] Transistor 320 is a transistor that uses metal oxide (also known as oxide semiconductor) in the semiconductor layer that forms the channel.

[0260] The transistor 320 includes a semiconductor layer 321, an insulating layer 323, a conductive layer 324, a pair of conductive layers 325, an insulating layer 326, and a conductive layer 327.

[0261] The substrate 331 corresponds to the substrate 291 in Figures 13A and 13B. The stacked structure 401 from the substrate 331 to the insulating layer 255 corresponds to the substrate 101 in Embodiment 1. An insulating substrate or a semiconductor substrate can be used as the substrate 331.

[0262] An insulating layer 332 is provided on the substrate 331. The insulating layer 332 serves as a barrier layer, preventing impurities such as water or hydrogen from diffusing from the substrate 331 to the transistor 320 and preventing oxygen from detaching from the semiconductor layer 321 towards the insulating layer 332. 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.

[0263] 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 a silicon oxide film. Preferably, the top surface of the insulating layer 326 is planarized.

[0264] 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 that can be used for the semiconductor layer 321 will be described in detail later.

[0265] A pair of conductive layers 325 are disposed on the semiconductor layer 321 in contact with the semiconductor layer 321 and serve as source electrode and drain electrode.

[0266] 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.

[0267] 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.

[0268] The top surfaces of the conductive layer 324, the insulating layer 323, and the insulating layer 264 are planarized so that their heights are approximately the same, and insulating layers 329 and 265 are provided to cover them.

[0269] 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.

[0270] 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 has a conductive layer 274a covering the side surfaces of the openings of each of the insulating layers 265, 329, 264, and 328, and a portion of the top surface of the conductive layer 325, and a conductive layer 274b in contact with the top surface of the conductive layer 274a. Preferably, the conductive layer 274a is made of a conductive material that does not readily diffuse hydrogen and oxygen.

[0271] 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.

[0272] [Display Device 400E] In the display device 400E shown in FIG16, a transistor 310 with a channel formed on a substrate 301 and a transistor 320 with a metal oxide semiconductor layer forming the channel are stacked. Note that the description of the same parts as those in display devices 400C and 400D is sometimes omitted.

[0273] 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.

[0274] 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.

[0275] 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.

[0276] 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.

[0277] 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.

[0278] In this specification, etc., devices manufactured using a metal mask or FMM (Fine Metal Mask) are sometimes referred to as devices having an MM (Metal Mask) structure. In addition, in this specification, etc., devices manufactured without a metal mask or FMM are sometimes referred to as devices having an MML (Metal Mask Less) structure.

[0279] Furthermore, in this specification, the structure in which light-emitting devices of each color (here, blue (B), green (G), and red (R)) are separately formed or coated with light-emitting layers is sometimes referred to as an SBS (Side By Side) structure. Additionally, in this specification, a light-emitting device capable of emitting white light is sometimes referred to as a white light-emitting device. A white light-emitting device, combined with a color layer (e.g., a color filter), can realize a display device that displays in full color.

[0280] Furthermore, light-emitting devices can be broadly classified into single-structure and series-structure devices. A preferred single-structure device has the following structure: a light-emitting unit is included between a pair of electrodes, and this light-emitting unit includes one or more light-emitting layers. To obtain white light emission, the light-emitting layers are selected such that the light emission of each of the two or more light-emitting layers is in a complementary color relationship. For example, by making the light emission color of the first light-emitting layer complementary to the light emission color of the second light-emitting layer, a structure in which the light-emitting device as a whole emits white light can be obtained. The same applies to light-emitting devices including three or more light-emitting layers.

[0281] The series-connected device preferably has the following structure: two or more light-emitting units are included between a pair of electrodes, and each light-emitting unit includes one or more light-emitting layers. To obtain white light emission, a structure is used to combine the light emitted from the light-emitting layers of the multiple light-emitting units to obtain white light emission. Note that the structure for obtaining white light emission is the same as the structure in the single-structure device. Furthermore, in the series-connected device, it is preferable to provide an intermediate layer such as a charge-generating layer between the multiple light-emitting units.

[0282] Furthermore, when comparing the aforementioned white light-emitting devices (single-structure or series-structure) and SBS structure light-emitting devices, the SBS structure light-emitting device can achieve lower power consumption than the white light-emitting device. Therefore, when power consumption reduction is desired, the SBS structure light-emitting device is preferred. On the other hand, the manufacturing process for white light-emitting devices is simpler than that for SBS structure light-emitting devices, thereby reducing manufacturing costs or increasing manufacturing yield, making it preferable.

[0283] <Structural Example of a Light-Emitting Element> As shown in Figure 17A, the light-emitting element includes an EL layer 686 between a pair of electrodes (electrode 672, electrode 688). The EL layer 686 may be composed of multiple layers such as layer 4420, light-emitting layer 4411, and layer 4430. Layer 4420 may, for example, include 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 light-emitting 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).

[0284] 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 FIG17A is referred to as a single structure.

[0285] In addition, as shown in Figure 17B, the structure in which multiple light-emitting layers (light-emitting layers 4411, 4412, 4413) are disposed between layer 4420 and layer 4430 is also a variant example of a single structure.

[0286] As shown in FIG17C, the structure in which multiple light-emitting units (EL layers 686a, 686b) 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 FIG17C 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.

[0287] Furthermore, when comparing single-structure, series-structure, and SBS structure, power consumption can be reduced by following the order of SBS structure, series structure, and single-structure. When power consumption reduction is desired, the SBS structure is preferred. On the other hand, the manufacturing process for single-structure and series-structure is simpler than that for SBS structure, thereby reducing manufacturing costs or increasing manufacturing yield, and therefore they are preferred.

[0288] 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 686. Furthermore, when the light-emitting element has a microcavity structure, the color purity can be further improved.

[0289] Preferably, the white light-emitting element has a structure in which the light-emitting layer contains two or more light-emitting materials. In order to obtain white light emission, two or more light-emitting materials whose light emission is in a complementary color relationship can be selected. 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 complementary colors, a light-emitting element that emits white light throughout the light-emitting element can be obtained. Furthermore, the same applies to light-emitting elements that include three or more light-emitting layers.

[0290] Preferably, the luminescent layer comprises two or more luminescent materials, each emitting light in the form of R (red), G (green), B (blue), Y (yellow), O (orange), etc. Alternatively, it preferably comprises two or more luminescent materials, each emitting light in the form of two or more spectral components of R, G, and B.

[0291] 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.

[0292] Embodiment 5 In this embodiment, a metal oxide (referred to as an oxide semiconductor) that can be used in the OS transistor described in the above embodiments is explained.

[0293] 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 boron, silicon, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, magnesium and cobalt.

[0294] In addition, metal oxides can be formed by CVD methods such as sputtering, metal-organic chemical vapor deposition (MOCVD), or ALD methods.

[0295] <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.

[0296] 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.

[0297] 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.

[0298] 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 was observed in the diffraction pattern of an IGZO film formed at room temperature, but no halo was observed. Therefore, it can be inferred that the IGZO film formed 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.

[0299] <<Structure of Oxide Semiconductors>> Furthermore, when focusing on the structure of oxide semiconductors, the classification of oxide semiconductors sometimes differs from the above classification. 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.

[0300] Here, we will explain the details of CAAC-OS, nc-OS and a-like OS mentioned above.

[0301] [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.

[0302] 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.

[0303] 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.

[0304] 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 metallic elements constituting CAAC-OS.

[0305] 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.

[0306] 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 regular hexagons; 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.

[0307] 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.

[0308] 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.

[0309] [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 has tiny crystals. Furthermore, for example, the size of these tiny crystals is larger than 1 nm and smaller than 10 nm, particularly larger than 1 nm and smaller than 3 nm; these tiny crystals are referred to as nanocrystals. Moreover, no regularity of 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.

[0310] [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.

[0311] <<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.

[0312] [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.

[0313] 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.

[0314] 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.

[0315] 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.

[0316] Note that sometimes the clear boundary between the first region and the second region mentioned above cannot be observed.

[0317] 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.

[0318] CAC-OS can be formed, for example, by sputtering without intentionally 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%.

[0319] 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 structure of regions with In as the main component (first region) and regions with Ga as the main component (second region) can be identified.

[0320] 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 the conductivity of 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.

[0321] 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.

[0322] 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 conduction / turn-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.

[0323] Furthermore, transistors using CAC-OS exhibit high reliability. Therefore, CAC-OS is best suited for various semiconductor devices such as display devices.

[0324] 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.

[0325] <Transistor with oxide semiconductor> Here, we will explain the case where the above-mentioned oxide semiconductor is used as a transistor.

[0326] 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.

[0327] 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 nature" or "substantially high purity nature". In addition, oxide semiconductors with low carrier concentration are sometimes referred to as "high purity nature or substantially high purity nature oxide semiconductors".

[0328] 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.

[0329] 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.

[0330] 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.

[0331] <Impurities> Here, the effects of various impurities in oxide semiconductors are explained.

[0332] 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.

[0333] Furthermore, when an oxide semiconductor contains an alkali metal or an alkaline earth metal, defect states sometimes form, 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.

[0334] When an oxide semiconductor contains nitrogen, electrons are readily 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.

[0335] 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.

[0336] By using oxide semiconductors with sufficiently reduced impurities in the channel formation region of the transistor, the transistor can have stable electrical characteristics.

[0337] At least a portion of this embodiment may be implemented in combination with other embodiments described in this specification.

[0338] Embodiment 6 In this embodiment, an electronic device according to an embodiment of the present invention will be described using Figures 18A to 21F.

[0339] 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.

[0340] 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.

[0341] 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 camcorders, digital photo frames, mobile phones, portable game consoles, portable information terminals, and audio playback devices.

[0342] 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 devices and MR devices can also be cited as wearable devices.

[0343] 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.

[0344] 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.

[0345] 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.

[0346] 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).

[0347] 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.

[0348] The electronic device 6500 shown in Figure 18A is a portable information terminal device that can be used as a smartphone.

[0349] 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.

[0350] The display unit 6502 may use a display device according to an embodiment of the present invention.

[0351] Figure 18B is a cross-sectional view of one end of the microphone 6506 including the housing 6501.

[0352] 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.

[0353] 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).

[0354] 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.

[0355] 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.

[0356] Figure 19A 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.

[0357] A display device according to an embodiment of the present invention can be applied to the display unit 7000.

[0358] The television 7100 shown in FIG19A 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 data output from the remote control 7111. Channel and volume can be adjusted using the operation keys or touch panel provided in the remote control 7111, and the images displayed on the display unit 7000 can be manipulated.

[0359] 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.

[0360] Figure 19B 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.

[0361] A display device according to an embodiment of the present invention can be applied to the display unit 7000.

[0362] Figures 19C and 19D show an example of a digital signage.

[0363] The digital signage 7300 shown in Figure 19C includes a housing 7301, a display unit 7000, and a speaker 7303. It may also include LED lights, operation keys (including a power switch or operation switch), connection terminals, various sensors, a microphone, etc.

[0364] Figure 19D 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.

[0365] In Figures 19C and 19D, a display device according to an embodiment of the present invention can be applied to the display unit 7000.

[0366] 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 people's attention, for example, it can improve the effectiveness of advertising.

[0367] 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.

[0368] As shown in Figures 19C and 19D, 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.

[0369] 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.

[0370] Figure 20A is an external view of a camera 8000 equipped with a viewfinder 8100.

[0371] The camera 8000 includes a housing 8001, a display unit 8002, an operation button 8003, a shutter button 8004, etc. In addition, the camera 8000 is equipped with a detachable lens 8006. In the camera 8000, the lens 8006 and the housing 8001 can also be formed as one piece.

[0372] The camera 8000 can take pictures by pressing the shutter button 8004 or touching the display 8002, which is used as a touch panel.

[0373] The housing 8001 includes an insert with electrodes, which can be connected to the viewfinder 8100 and to a flash unit, etc.

[0374] The viewfinder 8100 includes a housing 8101, a display unit 8102, and buttons 8103, etc.

[0375] 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.

[0376] Button 8103 is used as a power button, etc.

[0377] 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.

[0378] Figure 20B is an external view of the head-mounted display 8200.

[0379] 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.

[0380] 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 allowing the use of information from the user's eyeball or eyelid movements as an input method.

[0381] 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.

[0382] The display device of one embodiment of the present invention can be used in the display unit 8204.

[0383] Figures 20C to 20E 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.

[0384] 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 seeing the image displayed on different areas of the display unit 8302 through the lens 8305, three-dimensional display 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 so that one display unit is provided for each of the user's two eyes.

[0385] 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 FIG20E, 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 view images with a higher degree of realism.

[0386] Figure 20F 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.

[0387] 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.

[0388] 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.

[0389] 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 the buffer member 8403 is made of a component that covers the surface of the sponge or the like with cloth or leather (natural or synthetic leather), 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 that components in contact with the user's skin, such as the buffer member 8403 or the mounting part 8402, have a detachable structure, making cleaning and replacement easier.

[0390] The electronic device shown in Figures 21A to 21F 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.

[0391] The electronic devices shown in Figures 21A to 21F 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; touch panel function; displaying calendars, dates, or times, etc.; control processing via various software (programs); wireless communication function; 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.

[0392] The display device of one embodiment of the present invention can be used in the display unit 9001.

[0393] The electronic devices shown in Figures 21A to 21F will now be described in detail.

[0394] Figure 21A 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 21A. 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.

[0395] Figure 21B 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 the 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 determining whether to answer a phone call.

[0396] Figure 21C 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.

[0397] Figures 21D to 21F are perspective views showing the foldable portable information terminal 9201. Furthermore, Figure 21D is a perspective view of the portable information terminal 9201 in its unfolded state, Figure 21F is a perspective view of its folded state, and Figure 21E is a perspective view of the intermediate state during the transition from one of the states in Figures 21D and 21F 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.

[0398] 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. [Simplified Explanation of the Diagram]

[0022] Figures 1A to 1D are diagrams showing examples of the structure of a display device. Figures 2A to 2E are diagrams showing examples of a manufacturing method of a display device. Figures 3A to 3D are diagrams showing examples of a manufacturing method of a display device. Figures 4A to 4E are diagrams showing examples of a manufacturing method of a display device. Figures 5A to 5C are diagrams showing examples of the structure of a display device. Figures 6A to 6D are diagrams showing examples of a manufacturing method of a display device. Figures 7A to 7E are diagrams showing examples of a manufacturing method of a display device. Figures 8A and 8B are diagrams showing examples of the structure of a display device. Figures 9A to 9F are diagrams showing examples of a manufacturing method of a display device. Figure 10 is a perspective view showing an example of a display device. Figures 11A and 11B are cross-sectional views showing an example of a display device. Figure 12A is a cross-sectional view showing an example of a display device. [Fig. 12B] is a cross-sectional view showing an example of a transistor. [Fig. 13A] and [Fig. 13B] are perspective views showing an example of a display module. [Fig. 14] is a cross-sectional view showing an example of a display device. [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. 17A] to [Fig. 17C] are diagrams showing examples of the structure of a light-emitting element. [Fig. 18A] and [Fig. 18B] are diagrams showing an example of an electronic device. [Fig. 19A] to [Fig. 19D] are diagrams showing an example of an electronic device. [Fig. 20A] to [Fig. 20F] are diagrams showing an example of an electronic device. [Fig. 21A] to [Fig. 21F] are diagrams showing an example of an electronic device.

Claims

1. A method for manufacturing a display device, comprising the following processes: a first process of depositing a first EL film on a first pixel electrode and a second pixel electrode; a second process of forming a first sacrificial film to cover the first EL film; a third process of etching the first sacrificial film and the first EL film to expose the second pixel electrode and forming a first EL layer on the first pixel electrode and a first sacrificial layer on the first EL layer; a fourth process of depositing a second EL film on the first sacrificial layer and the second pixel electrode; a fifth process of forming a second sacrificial film to cover the second EL film; a sixth process of etching the second sacrificial film and the second EL film to expose the first sacrificial layer and forming a second EL layer on the second pixel electrode and a second sacrificial layer on the second EL layer; a seventh process of removing the first sacrificial layer and the second sacrificial layer; and an eighth process of drying the first EL layer and the second EL layer, wherein, The first EL film and the second EL film are etched by dry etching, and the first sacrificial layer and the second sacrificial layer are removed by wet etching.

2. The method of manufacturing a display device as claimed in claim 1, wherein the first sacrificial film comprises a resin material soluble in water or alcohol, in the third process, the first sacrificial film and the first EL film are continuously etched by dry etching in an oxygen-containing atmosphere, and in the seventh process, the first sacrificial layer and the second sacrificial layer are removed by dissolving in water or alcohol.

3. The method for manufacturing a display device as claimed in claim 1, wherein the first sacrificial film comprises a metal film, an alloy film, a metal oxide film, a semiconductor film, or an inorganic insulating film, wherein in the third process, the first EL film is etched by dry etching using an etching gas whose main component does not contain oxygen, and wherein in the seventh process, the first sacrificial layer and the second sacrificial layer are removed by wet etching using an aqueous solution of tetramethylammonium hydroxide, dilute hydrofluoric acid, oxalic acid, phosphoric acid, acetic acid, nitric acid, or a mixture thereof.

4. The method of manufacturing a display device as claimed in claim 1 or 3, further comprising a ninth process for forming a hard mask between the second process and the third process, wherein in the third process, after etching the first sacrificial film using the hard mask, the hard mask and the first EL film are etched using the same process.

5. A method for manufacturing a display device as claimed in any of claims 1 to 4, wherein the first EL layer and the second EL layer are both processed in a strip-like manner with their top surfaces in shape.

6. A method for manufacturing a display device as claimed in any of claims 1 to 4, wherein the first EL layer and the second EL layer are both processed such that their top surfaces are island-shaped.

7. The method of manufacturing a display device according to any one of claims 1 to 6 further includes the following process after the eighth process: a tenth process of forming a common electrode on the first EL layer and the second EL layer; and an eleventh process of forming a protective layer on the common electrode.

8. The method of manufacturing the display device as claimed in claim 7, further comprising a twelfth process after the eighth process and before the tenth process, wherein a common layer is formed on the first EL layer and the second EL layer.

9. The method of manufacturing a display device according to any one of claims 1 to 8, further comprising, prior to the first process, a thirteenth process of forming optical adjustment layers of different thicknesses on the first pixel electrode and the second pixel electrode.

10. A method for manufacturing a display device, comprising the following processes: a first process of depositing an EL film on a first pixel electrode and a second pixel electrode; a second process of forming a sacrificial film to cover the EL film; a third process of etching the sacrificial film and the EL film to form a first EL layer on the first pixel electrode, a first sacrificial layer on the first EL layer, a second EL layer on the second pixel electrode, and a second sacrificial layer on the second EL layer; a fourth process of removing the first sacrificial layer and the second sacrificial layer; and a fifth process of drying the first EL layer and the second EL layer, wherein, In the third process, the EL film is etched by dry etching. In the fourth process, the first sacrificial layer is removed by wet etching. The EL film includes a light-emitting layer that emits white light.