Display device

Abstract

Provided is a high-definition display device. Also provided is a display device having a high aperture ratio. The display device comprises: a first pixel electrode; a second pixel electrode; a first insulating layer; a second insulating layer; a first EL layer; a second EL layer; and a common electrode. The first insulating layer covers ends of the first and second pixel electrodes. The second insulating layer is provided on the first and second pixel electrodes and the first insulating layer, and covers an end of the first insulating layer. The first EL layer is provided on the first pixel electrode, and the second EL layer is provided on the second pixel electrode. Ends of the first and second EL layers face each other, and overlap the first insulating layer. The common electrode has a part overlapping the first EL layer and a part overlapping the second EL layer. The first insulating layer includes an organic resin, and the second insulating layer includes an inorganic insulating material.

Description

display device

[0001] FIELD OF THE INVENTION One embodiment of the present invention relates to a display device and a manufacturing method of the display device.

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

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

[0004] Representative examples of display devices applicable to the display panel include liquid crystal display devices, organic EL (Electro Luminescence) elements, light-emitting devices equipped with light-emitting elements such as light-emitting diodes (LEDs: Light Emitting Diodes), and electronic paper that displays using an electrophoresis method.

[0005] For example, Patent Document 1 describes an example of a display device for VR that uses organic EL elements.

[0006] International Publication No. 2018 / 087625

[0007] An object of one embodiment of the present invention is to provide a high-resolution display device.An object of one embodiment of the present invention is to provide a display device with a high aperture ratio.An object of one embodiment of the present invention is to provide a display device which combines high display quality and high resolution.An object of one embodiment of the present invention is to provide a display device with high contrast.An object of one embodiment of the present invention is to provide a highly reliable display device.

[0008] An object of one embodiment of the present invention is to provide a display device having a novel structure or a manufacturing method of the display device.An object of one embodiment of the present invention is to provide a method for manufacturing the above-described display device with high yield.An object of one embodiment of the present invention is to alleviate at least one of the problems of the prior art.

[0009] Note that the description of these problems does not preclude the existence of other problems. Note that one embodiment of the present invention does not necessarily solve all of these problems. Note that problems other than these can be extracted from the description of the specification, drawings, claims, etc.

[0010] One embodiment of the present invention is a display device including a first pixel electrode, a second pixel electrode, a first insulating layer, a second insulating layer, a first EL layer, a second EL layer, and a common electrode. The first pixel electrode and the second pixel electrode are provided side by side. The first insulating layer covers an end portion of the first pixel electrode and an end portion of the second pixel electrode. One end portion of the first insulating layer overlaps with a top surface of the first pixel electrode, and another end portion overlaps with a top surface of the second pixel electrode. The second insulating layer is provided over the first pixel electrode, the second pixel electrode, and the first insulating layer, and covers the end portion of the first insulating layer. One end portion of the second insulating layer overlaps with a top surface of the first pixel electrode, and another end portion overlaps with a top surface of the second pixel electrode. The first EL layer is provided over the first pixel electrode, and the second EL layer is provided over the second pixel electrode. The first EL layer and the second EL layer have an end portion facing each other and overlapping with the first insulating layer. The common electrode has a portion overlapping with the first EL layer and a portion overlapping with the second EL layer. The first insulating layer contains an organic resin, and the second insulating layer contains an inorganic insulating material.

[0011] In the above, the first insulating layer preferably has a curved surface between the top surface and the end portion, and the second insulating layer preferably has a portion where the angle between the side surface and the bottom surface is 20 degrees or more and less than 90 degrees.

[0012] In any of the above, the first insulating layer preferably contains an acrylic resin, a polyimide resin, an epoxy resin, a polyamide resin, a polyimideamide resin, a siloxane resin, a benzocyclobutene-based resin, a phenolic resin, or a precursor of these resins.

[0013] In any of the above, the second insulating layer preferably contains silicon oxide, silicon oxynitride, silicon nitride oxide, silicon nitride, aluminum oxide, aluminum oxynitride, hafnium oxide, indium gallium oxide, or indium gallium zinc oxide.

[0014] In any of the above, the second insulating layer may have a recess in a region that does not overlap with either the first EL layer or the second EL layer, or the second insulating layer may be divided in a region that does not overlap with either the first EL layer or the second EL layer.

[0015] In any of the above, the second insulating layer preferably includes a first insulating film and a second insulating film on the first insulating film, and in this case, it is preferable that a first angle formed between a side surface and a bottom surface of the first insulating film is different from a second angle formed between a side surface and a bottom surface of the second insulating film.

[0016] In the above, it is preferable that the first insulating film is thinner than the second insulating film and the first angle is larger than the second angle. Alternatively, it is preferable that the second insulating film is thinner than the first insulating film and the second angle is larger than the first angle.

[0017] In any of the above, it is preferable that the first insulating film includes a silicon nitride film, and the second insulating film includes a silicon oxide film.

[0018] Another embodiment of the present invention is a method for manufacturing a display device, including: forming a first pixel electrode and a second pixel electrode; forming a photosensitive resin film to cover the first pixel electrode and the second pixel electrode; exposing the resin film using a first photomask and developing it to form a first insulating layer that covers an end portion of the first pixel electrode and an end portion of the second pixel electrode; forming an inorganic insulating film to cover the first pixel electrode, the second pixel electrode, and the first insulating layer; forming a resist film over the inorganic insulating film; exposing the resist film using the first photomask and developing it to form a resist mask; and etching the inorganic insulating film that is not covered by the resist mask to form a second insulating layer that covers an upper surface of the first pixel electrode, an upper surface of the second pixel electrode, and an upper surface of the first insulating layer.

[0019] In the above, after forming the second insulating layer, it is preferable to form the first EL layer on the first pixel electrode, the second EL layer on the second pixel electrode, and a common electrode on the first EL layer and the second EL layer. In this case, it is preferable that the first EL layer and the second EL layer are processed into an island shape or a strip shape by photolithography.

[0020] According to one embodiment of the present invention, a high-resolution display device can be provided. Alternatively, a display device having both high display quality and high resolution can be provided. Alternatively, a display device with high contrast can be provided. Alternatively, a display device with high reliability can be provided.

[0021] According to one embodiment of the present invention, it is possible to provide a display device having a novel structure, a manufacturing method of the display device, a method for manufacturing the display device with high yield, or at least one of the problems of the prior art.

[0022] Note that the description of these effects does not preclude the existence of other effects. Note that one embodiment of the present invention does not necessarily have all of these effects. Note that effects other than these can be extracted from the description in the specification, drawings, claims, etc.

[0023] FIGS. 1A to 1D are diagrams showing a structural example of a display device. FIGS. 2A and 2B are diagrams showing a structural example of a display device. FIGS. 3A to 3C are diagrams showing a structural example of a display device. FIGS. 4A to 4C are diagrams showing a structural example of a display device. FIGS. 5A to 5G are diagrams showing a manufacturing method example of a display device. FIGS. 6A to 6F are diagrams showing a manufacturing method example of a display device. FIGS. 7A to 7E are diagrams showing a manufacturing method example of a display device. FIGS. 8A to 8C are diagrams showing a manufacturing method example of a display device. FIGS. 9A to 9C are diagrams showing a manufacturing method example of a display device. FIGS. 10A to 10C are diagrams showing a structural example of a display device. FIGS. 11A to 11C are diagrams showing a structural example of a display device. FIGS. 12A to 12C are diagrams showing a structural example of a display device. FIG. 13 is a perspective view showing an example of a display device. FIGS. 14A and 14B are cross-sectional views showing an example of a display device. FIG. 15A is a cross-sectional view showing an example of a display device. FIG. 15B is a cross-sectional view showing an example of a transistor. 16A to 16D are diagrams showing an example of the configuration of a light-emitting element. FIGS. 17A to 17J are diagrams showing an example of the configuration of a display device. FIGS. 18A and 18B are diagrams showing an example of an electronic device. FIGS. 19A to 19D are diagrams showing an example of an electronic device. FIGS. 20A to 20F are diagrams showing an example of an electronic device. FIGS. 21A to 21F are diagrams showing an example of an electronic device. FIG. 22A is a cross-sectional observation image. FIG. 22B is a schematic cross-sectional view.

[0024] Hereinafter, embodiments will be described with reference to the drawings. However, it will be readily understood by those skilled in the art that the embodiments can be implemented in many different ways and that various changes in form and details can be made without departing from the spirit and scope of the present invention. Therefore, the present invention should not be interpreted as being limited to the following description of the embodiments.

[0025] In the configuration of the invention described below, the same parts or parts having similar functions are denoted by the same reference numerals in different drawings, and repeated explanations thereof will be omitted. In addition, when referring to similar functions, the same hatch pattern may be used and no particular reference numeral may be assigned.

[0026] In the drawings described in this specification, the size of each component, the thickness of a layer, or an area may be exaggerated for clarity, and therefore, the drawings are not necessarily limited to the scale.

[0027] In this specification, ordinal numbers such as "first" and "second" are used to avoid confusion of components and do not limit the number.

[0028] Furthermore, in this specification and the like, the terms "film" and "layer" are interchangeable. For example, the terms "conductive layer" and "insulating layer" may be interchangeable with the terms "conductive film" and "insulating film."

[0029] In this specification, the EL layer refers to a layer provided between a pair of electrodes of a light-emitting element and containing at least a light-emitting substance (also referred to as a light-emitting layer), or a stack including a light-emitting layer.

[0030] In this specification and the like, a display panel, which is one aspect of a display device, has a function of displaying (outputting) an image or the like on a display surface, and therefore the display panel is one aspect of an output device.

[0031] In addition, in this specification, a display panel having a connector such as an FPC (Flexible Printed Circuit) or a TCP (Tape Carrier Package) attached to the substrate, or a display panel having an IC mounted on the substrate using a COG (Chip On Glass) method or the like, may be referred to as a display panel module, a display module, or simply a display panel.

[0032] Embodiment 1 In this embodiment, a structural example of a display device according to one embodiment of the present invention and an example of a manufacturing method of the display device will be described.

[0033] One embodiment of the present invention is a display device having a light-emitting element (also referred to as a light-emitting device). The display device has at least two light-emitting elements that emit different colors of light. Each light-emitting element has a pair of electrodes and an EL layer therebetween. The light-emitting element is preferably an organic EL element (organic electroluminescent element). Two or more light-emitting elements that emit different colors each have an EL layer containing a different material. For example, a full-color display device can be realized by having three types of light-emitting elements that emit red (R), green (G), or blue (B) light, respectively.

[0034] Here, when forming a part or all of the EL layer separately for light-emitting elements with different emission colors, it is known to form the layer by a vapor deposition method using a shadow mask such as a metal mask. However, with this method, various factors, such as the accuracy of the metal mask, misalignment between the metal mask and the substrate, deflection of the metal mask, and the spread of the contours of the deposited film due to vapor scattering, can cause deviations in the shape and position of the island-shaped organic film from the design, making it difficult to achieve high resolution and a high aperture ratio for display devices. For this reason, measures have been taken to artificially increase the resolution (also known as pixel density) by applying special pixel arrangement methods such as a pentile arrangement.

[0035] In one embodiment of the present invention, an EL layer is processed into a fine pattern without using a shadow mask such as a metal mask. This makes it possible to realize a display device with high definition and a large aperture ratio, which have been difficult to achieve until now. Furthermore, because the EL layer can be individually fabricated, a display device with extremely vivid, high contrast, and high display quality can be realized.

[0036] For simplicity, a case where EL layers for two light-emitting elements are formed separately will be described. First, a first EL film and a first sacrificial film are laminated to cover two pixel electrodes. Next, a resist mask is formed on the first sacrificial film at a position overlapping one of the pixel electrodes (first pixel electrode). Next, a portion of the first sacrificial film that does not overlap with the resist mask and a portion of the first EL film are etched. At this time, the etching is stopped when the other pixel electrode (second pixel electrode) is exposed. As a result, a portion of the first EL film (also referred to as a 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 referred to as a first sacrificial layer) can be formed thereon.

[0037] Next, a second EL film and a second sacrificial film are stacked and formed. Then, a resist mask is formed in a position overlapping the second pixel electrode. Next, similarly to the above, a portion of the second sacrificial film and a portion of the second EL film that do not overlap with the resist mask are etched. As a result, a first EL layer and a first sacrificial layer are provided on the first pixel electrode, and a second EL layer and a second sacrificial layer are provided on the second pixel electrode. In this way, the first EL layer and the second EL layer can be separately formed. Finally, the first sacrificial layer and the second sacrificial layer are removed to expose the first EL layer and the second EL layer, and then a common electrode is formed, thereby separately forming two-color light-emitting elements.

[0038] Furthermore, by repeating the above steps, EL layers for light-emitting elements of three or more colors can be formed separately, and a display device having light-emitting elements of three or four or more colors can be realized.

[0039] Here, a first insulating layer is provided to cover the respective ends of the first pixel electrode and the second pixel electrode. By providing the first insulating layer, the step coverage of the first EL layer and the second EL layer can be improved. In addition, it is possible to prevent an increase in leakage current due to the first EL layer or the second EL layer becoming thinner at the ends of the first pixel electrode or the second pixel electrode, and an electrical short circuit between the first pixel electrode or the second pixel electrode and the common electrode.

[0040] Furthermore, a second insulating layer is provided to cover the first insulating layer. At this time, it is preferable that the second insulating layer is formed to have a larger pattern than the first insulating layer. Specifically, it is preferable that the first insulating layer is formed so as to be located inside the outline of the second insulating layer in a plan view. At this time, the first insulating layer is configured to be covered by the second insulating layer. Furthermore, the second insulating layer has an end portion that overlaps with each of the first pixel electrode and the second pixel electrode.

[0041] The second insulating layer is preferably an insulating film containing an inorganic insulating material. It is more preferable to use an insulating film that is etch-resistant to the etching steps of the first EL layer and the second EL layer. Furthermore, it is preferable to use an insulating film that is etch-resistant to the steps of removing the first sacrificial layer and the second sacrificial layer.

[0042] On the other hand, the first insulating layer is preferably an insulating film containing an organic insulating material such as an organic resin. In this case, the first insulating layer preferably has a curved surface with a gentle slope from the end portion to the upper surface. This can improve the step coverage of the first EL layer and the second EL layer.

[0043] By providing the second insulating layer on the first insulating layer, it is possible to prevent the first insulating layer from being partially or entirely etched when the first EL layer or the second EL layer is etched. Furthermore, by forming a recess in the first insulating layer during these etching processes, the difference in height between the top surfaces of the first EL layer and the second EL layer and the top surface of the first insulating layer becomes large, which prevents the common electrode from being broken when it is formed.

[0044] In this way, a highly reliable display device can be realized by covering the ends of the first pixel electrode and the second pixel electrode with a laminated film formed by stacking a first insulating layer containing an organic resin and a second insulating layer containing an inorganic insulating material.

[0045] Here, the first insulating layer and the second insulating layer are preferably processed using the same photomask (exposure mask). For example, the first insulating layer is formed by depositing a photosensitive organic resin, exposing it using a photomask, and then developing it. At this time, the exposure conditions are controlled to form the first insulating layer so that the pattern width is narrower than the pattern width of the photomask. The second insulating layer can be formed by forming a patterned resist mask on the insulating film using the photomask, and etching the portions not covered by the resist mask. At this time, the exposure conditions of the resist mask are controlled to form the resist mask so that the pattern width is wider than that of the first insulating layer. This allows insulating layers with different pattern widths to be created using the same photomask.

[0046] In order to supply a potential to the common electrode, an electrode (also referred to as a first electrode, a connection electrode, or the like) can be provided on the same surface as the pixel electrode, and the connection electrode and the common electrode can be electrically connected. The connection electrode is disposed outside the display unit where the pixels are provided. It is also preferable that a first insulating layer and a second insulating layer are provided on the connection electrode so as to cover the end portions thereof.

[0047] Here, in order to prevent the upper surface of the connection electrode from being exposed to etching when the first EL film is etched, it is preferable to provide a first sacrificial layer on the connection electrode as well. Similarly, it is preferable to provide a second sacrificial layer on the connection electrode when the second EL film is etched. The first sacrificial layer and the second sacrificial layer provided on the connection electrode can be removed by etching simultaneously with the first sacrificial layer on the first EL layer and the second sacrificial layer on the second EL layer.

[0048] While it is difficult to achieve a spacing of less than 10 μm between EL layers of different colors using a metal mask, the above method allows for a spacing of 3 μm or less, 2 μm or less, or even 1 μm or less. For example, by using an exposure device for LSIs, the spacing can be narrowed to 500 nm or less, 200 nm or less, 100 nm or less, or even 50 nm or less. This significantly reduces the area of ​​the non-light-emitting region that may exist between two light-emitting elements, enabling an aperture ratio approaching 100%. For example, an aperture ratio of 50% or more, 60% or more, 70% or more, 80% or more, or even 90% or more, but less than 100%, can be achieved.

[0049] Furthermore, the pattern of the EL layer itself can be made much smaller than when a metal mask is used. Furthermore, for example, when a metal mask is used to separately form an EL layer, thickness variations occur between the center and edges of the pattern, resulting in a smaller effective area that can be used as the light-emitting region relative to the overall area of ​​the pattern. On the other hand, with the above-described fabrication method, a pattern is formed by processing a film deposited to a uniform thickness, making it possible to achieve a uniform thickness within the pattern, and even with a fine pattern, almost the entire area can be used as the light-emitting region. Therefore, the above-described fabrication method can achieve both high definition and a high aperture ratio.

[0050] Furthermore, the first insulating layer and the second insulating layer provided between two adjacent pixel electrodes are provided so as to cover the edges of the pixel electrodes. Since the area on the pixel electrode covered by the second insulating layer does not function as a light-emitting area of ​​the light-emitting element, the smaller the width of the area where the second insulating layer and the pixel electrode overlap, the higher the effective light-emitting area ratio, i.e., the aperture ratio, of the display device can be.

[0051] Furthermore, the ends of the EL layer are located on the first insulating layer and the second insulating layer. In this case, the side surfaces of the two EL layers are disposed facing each other on the second insulating layer. The narrower the distance between the two EL layers, the smaller the width of the insulating layer can be, thereby increasing the aperture ratio of the display device. For example, the distance between the side surfaces of the two opposing EL layers is 5 μm or less, preferably 4 μm or less, more preferably 3 μm or less, even more preferably 2 μm or less, and even more preferably 1 μm or less, and can be 10 nm or more, 50 nm, or 100 nm or more.

[0052] As described above, one embodiment of the present invention can realize a display device integrating minute light-emitting elements. For example, since there is no need to artificially increase the resolution by applying a special pixel arrangement method such as a pen tile method, a display device can be realized that has a so-called stripe arrangement in which R, G, and B are arranged in one direction, and that has a resolution of 500 ppi or more, 1000 ppi or more, 2000 ppi or more, further 3000 ppi or more, or even 5000 ppi or more. Furthermore, a display device can be realized that has an effective light-emitting area ratio (aperture ratio) of 50% or more, further 60% or more, or further 70% or more, but less than 100%.

[0053] Furthermore, one embodiment of the present invention enables precise fabrication of minute light-emitting elements, and therefore enables the realization of a complex pixel arrangement. For example, various arrangement methods such as an S-stripe arrangement, a Bayer arrangement, a delta arrangement, and the like can be applied in addition to a stripe arrangement.

[0054] In this specification and the like, the effective light-emitting area ratio refers to the ratio of the area of ​​an area that can be considered as a light-emitting area within one pixel to the area of ​​one pixel calculated from the repeat pitch of pixels in a display device.

[0055] Below, a more specific example of a structure and an example of a manufacturing method of a display device of one embodiment of the present invention will be described with reference to the drawings.

[0056] 1A shows a schematic top view of a display device 100 according to one 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 FIG. 1A, the light-emitting regions of the light-emitting elements are labeled with R, G, and B to easily distinguish the light-emitting elements from one another.

[0057] The light emitting elements 110R, 110G, and 110B are arranged in a matrix. Fig. 1A shows a so-called stripe arrangement in which light emitting elements of the same color are arranged in one direction. The arrangement of the light emitting elements is not limited to this, and other arrangements such as an S-stripe arrangement, a delta arrangement, a Bayer arrangement, or a zigzag arrangement may also be used. A pentile arrangement may also be used.

[0058] The light emitting elements 110R, 110G, and 110B are arranged in the X direction. In addition, light emitting elements of the same color are arranged in the Y direction that intersects with the X direction.

[0059] As the light-emitting element 110R, the light-emitting element 110G, and the light-emitting element 110B, it is preferable to use an EL element such as an OLED (organic light-emitting diode) or a QLED (quantum-dot light-emitting diode). Examples of the light-emitting substance contained in the EL element include a substance that emits fluorescence (fluorescent material), a substance that emits phosphorescence (phosphorescent material), and a substance that exhibits thermally activated delayed fluorescence (thermally activated delayed fluorescence (TADF) material). As the light-emitting substance contained in the EL element, not only organic compounds but also inorganic compounds (such as quantum dot materials) can be used.

[0060] 1B is a schematic cross-sectional view corresponding to the dashed dotted line A1-A2 in FIG. 1A, and FIG. 1C is a schematic cross-sectional view corresponding to the dashed dotted line B1-B2.

[0061] 1B shows cross sections of light-emitting elements 110R, 110G, and 110B. The light-emitting element 110R has a pixel electrode 111R, an EL layer 112R, an EL layer 114, and a common electrode 113. The light-emitting element 110G has a pixel electrode 111G, an EL layer 112G, an EL layer 114, and a common electrode 113. The light-emitting element 110B has a pixel electrode 111B, an EL layer 112B, an EL layer 114, and a common electrode 113. The EL layer 114 and the common electrode 113 are provided in common to the light-emitting element 110R, the light-emitting element 110G, and the light-emitting element 110B. The EL layer 114 can also be referred to as a common layer.

[0062] The EL layer 112R of the light-emitting element 110R contains a light-emitting organic compound that emits light having an intensity in at least the red wavelength range. The EL layer 112G of the light-emitting element 110G contains a light-emitting organic compound that emits light having an intensity in at least the green wavelength range. The EL layer 112B of the light-emitting element 110B contains a light-emitting organic compound that emits light having an intensity in at least the blue wavelength range.

[0063] The EL layer 112R, the EL layer 112G, and the EL layer 112B may each include one or more of an electron injection layer, an electron transport layer, a hole injection layer, and a hole transport layer in addition to a layer containing a light-emitting organic compound (light-emitting layer). The EL layer 114 may not include a light-emitting layer. For example, the EL layer 114 includes one or more of an electron injection layer, an electron transport layer, a hole injection layer, and a hole transport layer.

[0064] Here, in the stacked structure of the EL layer 112R, the EL layer 112G, and the EL layer 112B, the uppermost layer, i.e., the layer in contact with the EL layer 114, is preferably a layer other than the light-emitting layer. For example, it is preferable to provide an electron injection layer, an electron transport layer, a hole injection layer, a hole transport layer, or a layer other than these to cover the light-emitting layer, and to configure the layer in contact with the EL layer 114. In this way, when fabricating each light-emitting element, the reliability of the light-emitting element can be improved by protecting the top surface of the light-emitting layer with another layer.

[0065] The pixel electrode 111R, pixel electrode 111G, and pixel electrode 111B are provided for each light-emitting element. The common electrode 113 and EL layer 114 are provided as a continuous layer common to each light-emitting element. A conductive film transmissive to visible light is used for either one of the pixel electrodes or the common electrode 113, and a conductive film reflective to visible light is used for the other. By making each pixel electrode transmissive and the common electrode 113 reflective, a bottom-emission display device can be obtained. Conversely, by making each pixel electrode reflective and the common electrode 113 transmissive, a top-emission display device can be obtained. Note that by making both the pixel electrodes and the common electrode 113 transmissive, a dual-emission display device can be obtained.

[0066] An insulating layer 131 is provided to cover the edges of the pixel electrode 111R, the pixel electrode 111G, and the pixel electrode 111B. The insulating layer 131 is preferably tapered. In this specification and the like, a tapered object means that the angle (also referred to as the taper angle) between the surface and the surface on which the object is formed in the region near the edge is greater than 0 degrees and less than 90 degrees, and the object has a cross-sectional shape in which the thickness increases continuously from the edge.

[0067] Furthermore, by using an organic resin for the insulating layer 131, the surface can be made gently curved, which improves the coverage of the film formed on the insulating layer 131.

[0068] Examples of materials that can be used for the insulating layer 131 include acrylic resin, polyimide resin, epoxy resin, polyamide resin, polyimideamide resin, siloxane resin, benzocyclobutene resin, phenol resin, and precursors of these resins.

[0069] An insulating layer 132 is provided on the insulating layer 131. The insulating layer 132 overlaps with the ends of the pixel electrode 111R, the pixel electrode 111G, and the pixel electrode 111B via the insulating layer 131. The insulating layer 132 is provided to cover the ends of the insulating layer 131. The insulating layer 132 has portions that contact the upper surfaces of the pixel electrode 111R, the pixel electrode 111G, and the pixel electrode 111B.

[0070] The insulating layer 132 preferably has a tapered shape, which can improve step coverage of a film formed over the insulating layer 132, such as an EL layer provided to cover an end portion of the insulating layer 132.

[0071] The insulating layer 132 is preferably thinner than the insulating layer 131. By forming the insulating layer 132 thin, the step coverage of a film formed over the insulating layer 132 can be improved.

[0072] Examples of inorganic insulating materials that can be used for the insulating layer 132 include oxides and nitrides such as silicon oxide, silicon oxynitride, silicon nitride oxide, silicon nitride, aluminum oxide, aluminum oxynitride, and hafnium oxide. In addition, yttrium oxide, zirconium oxide, gallium oxide, tantalum oxide, magnesium oxide, lanthanum oxide, cerium oxide, neodymium oxide, and the like may also be used.

[0073] Alternatively, a metal oxide film such as indium gallium oxide or indium gallium zinc oxide may be used as the insulating layer 132. Such a metal oxide film has electrical properties as a semiconductor and has high resistance, so there is almost no risk of electrical short-circuiting between the two pixel electrodes via the insulating layer 132.

[0074] The insulating layer 132 may also be a stack of films containing the above inorganic insulating materials. For example, it may have a stack structure in which a silicon oxide film or a silicon oxynitride film is stacked on a silicon nitride film, or a stack structure in which a silicon oxide film or a silicon oxynitride film is stacked on an aluminum oxide film. Silicon oxide films and silicon oxynitride films are particularly resistant to etching, and therefore are preferably disposed on the upper side. Furthermore, silicon nitride films and aluminum oxide films are films through which water, hydrogen, oxygen, and the like are resistant to diffusion. Therefore, by disposing them on the insulating layer 131 side, they function as a barrier layer that prevents gases desorbed from the insulating layer 131 from diffusing into the light-emitting element.

[0075] The EL layer 112R, the EL layer 112G, and the EL layer 112B each have a region in contact with the upper surface of the pixel electrode and a region in contact with the surface of the insulating layer 131. In addition, the ends of the EL layer 112R, the EL layer 112G, and the EL layer 112B are located on the insulating layer 131.

[0076] As shown in FIG. 1B, a gap is provided between the two EL layers between light-emitting elements that emit different colors. Furthermore, as shown in FIG. 1C, a gap is preferably provided between the two EL layers between light-emitting elements that emit the same color. In this manner, it is preferable that the EL layers 112R, 112G, and 112B are arranged so as not to contact each other. This effectively prevents current from flowing through two adjacent EL layers, which would otherwise cause unintended light emission. This allows for increased contrast and a display device with high display quality.

[0077] In the Y direction, the EL layers 112R, 112G, and 112B may be formed in a strip shape so that the EL layers 112R, 112G, and 112B are continuous between light-emitting elements of the same color. By forming the EL layers 112R, etc. in a strip shape, no space is needed to separate them, and the area of ​​the non-light-emitting region between the light-emitting elements can be reduced, thereby increasing the aperture ratio.

[0078] 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 a function of preventing impurities such as water from diffusing from above into each light emitting element.

[0079] The protective layer 121 may have, for example, a single-layer structure or a multilayer structure including at least an inorganic insulating film. Examples of the inorganic insulating film include oxide films or nitride films such as a silicon oxide film, a silicon oxynitride film, a silicon nitride oxide film, a silicon nitride film, an aluminum oxide film, an aluminum oxynitride film, and a hafnium oxide film. Alternatively, the protective layer 121 may be made of a semiconductor material such as indium gallium oxide or indium gallium zinc oxide.

[0080] Alternatively, the protective layer 121 may be a laminated film of an inorganic insulating film and an organic insulating film. For example, a configuration in which an organic insulating film is sandwiched between a pair of inorganic insulating films is preferable. Furthermore, it is preferable that the organic insulating film functions as a planarizing film. This allows the upper surface of the organic insulating film to be flat, thereby improving the coverage of the inorganic insulating film thereon and enhancing the barrier properties. Furthermore, since the upper surface of the protective layer 121 is flat, it is preferable that when a structure (e.g., a color filter, a touch sensor electrode, a lens array, etc.) is provided above the protective layer 121, the influence of uneven shapes caused by the structure below can be reduced.

[0081] 1A also shows a connection electrode 111C that is electrically connected to the common electrode 113. The connection electrode 111C is given a potential (e.g., an anode potential or a cathode potential) to be supplied to the common electrode 113. The connection electrode 111C is provided outside the display area where the light-emitting elements 110R and the like are arranged. Also in FIG. 1A, the common electrode 113 is shown by a dashed line.

[0082] The connection electrode 111C can be provided along the periphery of the display area. For example, it may be provided along one side of the periphery of the display area, or it may be provided over two or more sides of the periphery of the display area. That is, when the top surface of the display area has a rectangular shape, the top surface of the connection electrode 111C can have a strip shape, an L-shape, a U-shape (square bracket shape), a square shape, or the like.

[0083] Fig. 1D is a schematic cross-sectional view corresponding to dashed dotted line C1-C2 in Fig. 1A. Fig. 1D shows a connection portion 130 where the connection electrode 111C and the common electrode 113 are electrically connected. In the connection portion 130, the common electrode 113 is provided in contact with the connection electrode 111C, and a protective layer 121 is provided covering the common electrode 113. In addition, insulating layers 131 and 132 are provided covering the ends of the connection electrode 111C.

[0084] Next, preferred configurations of the insulating layer 131, the insulating layer 132, and their vicinity will be described in detail. Fig. 2A shows an enlarged view of the insulating layer 131, the insulating layer 132, and their vicinity between two adjacent light-emitting elements. Fig. 2B shows a further enlarged view of the end of the insulating layer 131, the end of the insulating layer 132, and their vicinity.

[0085] Note that, here, light-emitting element 110P and light-emitting element 110Q are shown as any two adjacent light-emitting elements. Light-emitting element 110P and light-emitting element 110Q are each independently any one of light-emitting element 110R, light-emitting element 110G, and light-emitting element 110B. Similarly, EL layer 112P and EL layer 112Q are each independently any one of EL layer 112R, EL layer 112G, and EL layer 112B, and pixel electrode 111P and pixel electrode 111Q are each independently any one of pixel electrode 111R, pixel electrode 111G, and pixel electrode 111B.

[0086] Each of the insulating layer 131 and the insulating layer 132 has a portion overlapping with the EL layer 112P, a portion overlapping with the EL layer 112Q, and a portion not overlapping with either of these.

[0087] The insulating layer 131 has a portion that overlaps with the pixel electrode 111P, a portion that overlaps with the pixel electrode 111Q, and a portion that does not overlap with either of these. The insulating layer 132 on the insulating layer 131 has a portion that contacts the pixel electrode 111P, a portion that overlaps with the pixel electrode 111P with the insulating layer 131 interposed therebetween, a portion that contacts the pixel electrode 111Q, and a portion that overlaps with the pixel electrode 111Q with the insulating layer 131 interposed therebetween.

[0088] As shown in FIG. 2B, the angle (called the taper angle) formed between the bottom surface and the side surface near the end of the insulating layer 131 is defined as an angle θ １ The angle between the bottom surface and the side surface near the end of the insulating layer 132 is defined as angle θ ２ Since the surface of the insulating layer 131 near the end has a curved shape, the tangent to the end of the insulating layer 131 is indicated by a broken line.

[0089] Angle θ of insulating layer 131 １ is the angle θ of the insulating layer 132 ２ By making the taper angle of the insulating layer 131 small, formation of a low-density region in the insulating layer 132 can be suppressed.

[0090] Angle θ of insulating layer 131 １ can be set to be greater than 0 degrees and less than 90 degrees, preferably 5 degrees or more and 70 degrees or less, more preferably 10 degrees or more and 60 degrees or less, and even more preferably 15 degrees or more and 50 degrees or less.

[0091] On the other hand, the angle θ of the insulating layer 132 ２ can be greater than 0 degrees and less than 90 degrees, preferably 10 degrees or more and less than 90 degrees, more preferably 20 degrees or more and less than 90 degrees, and even more preferably 25 degrees or more and 85 degrees or less.

[0092] When the surface of the insulating layer 131 is curved, the top surface and the side surface may be continuous and indistinguishable. In this case, among the surfaces near the ends of the insulating layer 131, the surface of the portion where the thickness increases from the end can be regarded as the side surface, and the surface of the portion where the thickness is constant can be regarded as the top surface.

[0093] 3A shows an example in which a portion of the top surface of the insulating layer 132 is etched to form a recess in part of the insulating layer 132. The thickness of the insulating layer 132 in the portion not covered by the EL layer 112P and the EL layer 112Q is thinner than the portion covered by these layers. Note that although the thickness of the portion of the insulating layer 132 covered by the EL layer 112P and the portion covered by the EL layer 112Q are shown to be equal in FIG. 3A, these thicknesses may be different.

[0094] FIG. 3B shows an example in which the portions of the insulating layer 132 that are not covered by the EL layer 112P and the EL layer 112Q are removed by etching, and the insulating layer 132 is divided into two.

[0095] 3C shows an example in which the end face of the insulating layer 132 is further recessed by etching in comparison with FIG. 3B. In FIG. 3C, a space 133 is formed surrounded by the EL layer 112P, the insulating layer 132, the insulating layer 131, and the EL layer 114.

[0096] 4A to 4C show cross sections of the insulating layer 131 and the insulating layer 132 near the end on the light-emitting element 110 side. The light-emitting element 110 has a pixel electrode 111, an EL layer 112, an EL layer 114, a common electrode 113, etc. The light-emitting element 110 is either the light-emitting element 110P or the light-emitting element 110Q.

[0097] 4A shows an example of a pixel electrode 111 having a laminated structure. The pixel electrode 111 has a conductive layer 111a and a conductive layer 111b laminated from the substrate 101 side.

[0098] Here, the conductive layer 111b is provided to cover the end portion of the conductive layer 111a, so that the surface of the conductive layer 111a can be protected by the conductive layer 111b.

[0099] The conductive layer 111a can be formed using a film that is reflective to light emitted from the EL layer 112. On the other hand, the conductive layer 111b can be formed using a film that is transparent to the light.

[0100] The conductive layer 111 a may be, for example, a metal film or an alloy film. It is preferable to use a metal film having high reflectivity to visible light, such as aluminum or silver, or an alloy film of these, for the conductive layer 111 a, because the light extraction efficiency of the light-emitting element 110 can be increased.

[0101] The conductive layer 111b can be formed using a conductive material that transmits visible light, such as indium oxide, indium tin oxide, indium zinc oxide, indium tin oxide containing silicon, or indium zinc oxide containing silicon.

[0102] 4B and 4C show an example in which the insulating layer 132 has a laminated structure. The insulating layer 132 has a laminated structure in which an insulating layer 132a and an insulating layer 132b are laminated from the substrate 101 side.

[0103] 4B, the insulating layer 132b is thicker than the insulating layer 132a. In this case, it is preferable that the taper angle of the insulating layer 132b is smaller than the taper angle of the insulating layer 132a.

[0104] 4C, the insulating layer 132a is thicker than the insulating layer 132b, and the taper angle of the insulating layer 132a is preferably smaller than the taper angle of the insulating layer 132b.

[0105] In this manner, when the insulating layer 132 has a stacked structure, the thicker the insulating layer 132, the smaller the taper angle, which can improve the step coverage of the EL layer 112.

[0106] The present invention is not limited to the above, and a thinner film may have a smaller taper angle than a thicker film. The insulating layer 132 may have a stacked structure of three or more layers.

[0107] [Manufacturing Method Example] An example of a manufacturing method of a display device according to one embodiment of the present invention will be described below with reference to the drawings. Here, the display device 100 shown in the above-described configuration example will be used as an example. Figures 5A to 8C are cross-sectional schematic views of each step in the manufacturing method of the display device exemplified below. Also, Figure 5A and other figures also show cross-sectional schematic views of the connection portion 130 and its vicinity on the right side.

[0108] Thin films (insulating films, semiconductor films, conductive films, etc.) constituting the display device can be formed using a sputtering method, a chemical vapor deposition (CVD) method, a vacuum evaporation method, a pulsed laser deposition (PLD) method, an atomic layer deposition (ALD) method, etc. CVD methods include a plasma enhanced chemical vapor deposition (PECVD) method and a thermal CVD method. One type of thermal CVD method is a metal organic chemical vapor deposition (MOCVD) method.

[0109] Furthermore, thin films (insulating films, semiconductor films, conductive films, etc.) constituting the display device can be formed by methods such as spin coating, dipping, spray coating, inkjet, dispensing, screen printing, offset printing, doctor knife method, slit coating, roll coating, curtain coating, knife coating, etc.

[0110] Furthermore, when processing the thin film that constitutes the display device, a photolithography method or the like can be used. Alternatively, the thin film may be processed by a nanoimprint method, a sandblasting method, a lift-off method, or the like. Furthermore, the island-shaped thin film may be directly formed by a film formation method using a shielding mask such as a metal mask.

[0111] There are two typical photolithography methods: one is to form a resist mask on the thin film to be processed, process the thin film by etching or the like, and then remove the resist mask; the other is to form a photosensitive thin film, and then process the thin film into the desired shape by exposure and development.

[0112] In photolithography, the light used for exposure may be, for example, i-line (wavelength 365 nm), g-line (wavelength 436 nm), h-line (wavelength 405 nm), or a mixture of these. Other light sources that can be used include ultraviolet light, KrF laser light, ArF laser light, etc. Exposure may also be performed by immersion exposure technology. Extreme ultraviolet (EUV) light, X-rays, etc. may also be used as light for exposure. An electron beam may also be used instead of light for exposure. Extreme ultraviolet light, X-rays, or an electron beam are preferred because they enable extremely fine processing. When exposure is performed by scanning a beam such as an electron beam, a photomask is not required.

[0113] For etching the thin film, dry etching, wet etching, sandblasting, or the like can be used.

[0114] [Preparation of Substrate 101] A substrate having heat resistance sufficient to withstand at least subsequent heat treatment can be used as the substrate 101. When an insulating substrate is used as the substrate 101, a glass substrate, a quartz substrate, a sapphire substrate, a ceramic substrate, an organic resin substrate, or the like can be used. In addition, a semiconductor substrate such as a single crystal semiconductor substrate made of silicon, silicon carbide, or the like, a polycrystalline semiconductor substrate, a compound semiconductor substrate such as silicon germanium, or an SOI substrate can be used.

[0115] In particular, it is preferable to use a substrate in which a semiconductor circuit including semiconductor elements such as transistors is formed on the semiconductor substrate or insulating substrate as the substrate 101. The semiconductor circuit preferably constitutes, for example, a pixel circuit, a gate line driving circuit (gate driver), a source line driving circuit (source driver), etc. In addition to the above, an arithmetic circuit, a memory circuit, etc. may also be configured.

[0116] [Formation of pixel electrodes 111R, 111G, 111B, and connection electrode 111C] Next, the pixel electrodes 111R, 111G, 111B, and connection electrode 111C are formed on the substrate 101 ( FIG. 5A ). First, a conductive film that will become the pixel electrodes is formed, a resist mask is formed by photolithography, and unnecessary portions of the conductive film are removed by etching. Then, the resist mask is removed, thereby forming the pixel electrodes 111R, 111G, and 111B.

[0117] When a conductive film reflective to visible light is used as each pixel electrode, it is preferable to use a material (such as silver or aluminum) with as high a reflectivity as possible over the entire wavelength range of visible light, which not only increases the light extraction efficiency of the light-emitting element but also improves color reproducibility.

[0118] [Formation of Insulating Layer 131] Subsequently, an insulating film 131f is formed to cover the pixel electrodes 111R, 111G, and 111B. As the insulating film 131f, a film containing a photosensitive organic resin can be used.

[0119] The insulating film 131f can be formed by a wet deposition method such as a spin coating method or an ink-jet method. After the deposition, a heat treatment is performed to volatilize the solvent in the material. Alternatively, the material may be hardened by the heat treatment.

[0120] After the insulating film 131f is formed, it is irradiated with light 152 using a photomask 151. Here, an example is shown in which the insulating film 131f is made of a material having so-called positive photosensitivity, which improves solubility in a developer when exposed to light.

[0121] Thereafter, a development process is performed to form an insulating layer 131 (FIG. 5C).

[0122] At this time, it is preferable to form the insulating layer 131 so that the pattern width of the insulating layer 131 is smaller than the pattern width of the mask pattern of the photomask 151 by adjusting the exposure time, exposure intensity, and the like in the exposure process. For example, exposure is performed under conditions such that the exposure amount is greater than the appropriate value.

[0123] [Formation of Insulating Layer 132] Subsequently, an insulating film 132f is formed to cover the insulating layer 131, the pixel electrode 111R, the pixel electrode 111G, the pixel electrode 111B, etc. (FIG. 5D).

[0124] The insulating film 132f can be formed using a film formation method such as an ALD method, a sputtering method, a CVD method, a PLD method, or an evaporation method, or a combination of these methods.

[0125] Next, a resist film 141f is formed on the insulating film 132f, and then the resist film 141f is irradiated with light 153 using a photomask 151 (FIG. 5E).

[0126] Subsequently, the resist film 141f is subjected to a development process to form a resist mask 141 (FIG. 5F).

[0127] Here, the same photomask 151 can be used for forming the insulating layer 131 and the resist mask 141. Note that it is not necessary to use the exact same photomask, and a photomask manufactured for forming the same pattern can be used. Since the photomask 151 can be shared between forming the insulating layer 131 and forming the resist mask 141, production costs can be reduced.

[0128] Note that the photomask used to form the insulating layer 131 and the photomask used to form the resist mask 141 may be different photomasks.

[0129] As shown in FIG. 5F, a resist mask 141 is preferably formed to encompass the insulating layer 131 .

[0130] Next, the insulating film 132f is etched in the portion not covered by the resist mask 141. Then, the resist mask 141 is removed, thereby forming the insulating layer 132 (FIG. 5G).

[0131] [Formation of EL Film 112Rf] Subsequently, an EL film 112Rf, which will later become the EL layer 112R, is formed on the pixel electrodes 111R, 111G, 111B, and insulating layer 132.

[0132] The EL film 112Rf includes a film containing at least a light-emitting compound. Alternatively, the EL film 112Rf may have a structure in which one or more of films functioning as an electron injection layer, an electron transport layer, a charge generation layer, a hole transport layer, or a hole injection layer are stacked. The EL film 112Rf can be formed by, for example, a vapor deposition method, a sputtering method, an inkjet method, or the like. However, the EL film 112Rf is not limited to these methods, and the above-described film formation methods can be used as appropriate.

[0133] As an example, the EL film 112Rf is preferably a stacked film in which a hole injection layer, a hole transport layer, a light-emitting layer, and an electron transport layer are stacked in this order. In this case, a film having an electron injection layer can be used as the EL layer 114 to be formed later. In particular, providing an electron transport layer to cover the light-emitting layer can prevent the light-emitting layer from being damaged in a later photolithography process, etc., thereby enabling the fabrication of a highly reliable light-emitting element. Furthermore, by using layers containing the same organic compound for the electron transport layer used in the EL film 112Rf, etc., and the electron injection layer used in the later EL layer 114, the bonding between them can be improved, resulting in a light-emitting element with high light-emitting efficiency and high reliability. For example, an organic compound with electron transport properties can be used for the electron transport layer, and a material containing the organic compound and a metal can be used for the electron injection layer.

[0134] It is preferable that the EL film 112Rf is formed so as not to be provided on the connection electrode 111C. For example, when the EL film 112Rf is formed by evaporation or sputtering, it is preferable to form the EL film 112Rf using a shielding mask so that the EL film 112Rf is not formed on the connection electrode 111C.

[0135] [Formation of Sacrificial Film 144a] Subsequently, the sacrificial film 144a is formed to cover the EL film 112Rf. The sacrificial film 144a is provided in contact with the upper surface of the connection electrode 111C.

[0136] The sacrificial film 144a can be a film that is highly resistant to the etching process of each EL film, such as the EL film 112Rf, i.e., a film with a large etching selectivity. The sacrificial film 144a can also be a film that has a large etching selectivity with respect to a sacrificial film, such as the sacrificial film 146a described below. Furthermore, it is particularly preferable to use a film that can be removed by wet etching, which causes little damage to each EL film, for the sacrificial film 144a.

[0137] The sacrificial film 144a may be, for example, an inorganic film such as a metal film, an alloy film, a metal oxide film, a semiconductor film, or an inorganic insulating film. The sacrificial film 144a may be formed by various film formation methods such as sputtering, evaporation, CVD, and ALD. In particular, the ALD method causes less film formation damage to the layer on which the sacrificial film 144a is formed, so it is preferable to form the sacrificial film 144a directly on the EL film 112Rf by using the ALD method.

[0138] The sacrificial film 144a may be made of a metal material such as gold, silver, platinum, magnesium, nickel, tungsten, chromium, molybdenum, iron, cobalt, copper, palladium, titanium, aluminum, yttrium, zirconium, or tantalum, or an alloy material containing such a metal material. In particular, it is preferable to use a low-melting-point material such as aluminum or silver.

[0139] The sacrificial film 144a may be made of a metal oxide such as indium gallium zinc oxide (In—Ga—Zn oxide, also referred to as IGZO). Other examples include 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), and indium gallium tin zinc oxide (In—Ga—Sn—Zn oxide). Alternatively, indium tin oxide containing silicon may be used.

[0140] Instead of the gallium, an element M (wherein M is one or more elements selected from aluminum, silicon, boron, yttrium, copper, vanadium, beryllium, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, and magnesium) may be used. In particular, it is preferable that M is one or more elements selected from gallium, aluminum, and yttrium.

[0141] The sacrificial film 144a may be made of an oxide such as aluminum oxide, hafnium oxide, or silicon oxide, a nitride such as silicon nitride or aluminum nitride, or an oxynitride such as silicon oxynitride. Such inorganic insulating materials can be formed by a film formation method such as a sputtering method, a CVD method, or an ALD method, but it is particularly preferable to use the ALD method for the sacrificial film 144a formed directly on the EL film 112Rf.

[0142] Furthermore, the sacrificial film 144a may be made of a material that is soluble in a chemically stable solvent, at least for the film located at the top of the EL film 112Rf. In particular, materials that dissolve in water or alcohol are suitable for use in the sacrificial film 144a. When forming the sacrificial film 144a, it is preferable to apply the sacrificial film 144a by a wet film formation method while dissolving it in a solvent such as water or alcohol, and then perform a heat treatment to evaporate the solvent. In this case, performing the heat treatment under a reduced pressure atmosphere is preferable because it allows the solvent to be removed at a low temperature and in a short time, thereby reducing thermal damage to the EL film 112Rf.

[0143] Wet film formation methods that can be used to form the sacrificial film 144a include spin coating, dipping, spray coating, inkjet, dispensing, screen printing, offset printing, doctor knife method, slit coating, roll coating, curtain coating, and knife coating.

[0144] The sacrificial film 144a may be made of an organic material such as polyvinyl alcohol (PVA), polyvinyl butyral, polyvinyl pyrrolidone, polyethylene glycol, polyglycerin, pullulan, water-soluble cellulose, or alcohol-soluble polyamide resin.

[0145] [Formation of Sacrificial Film 146a] Subsequently, a sacrificial film 146a is formed on the sacrificial film 144a (FIG. 6A).

[0146] The sacrificial film 146a is a film that is used as a hard mask when etching the sacrificial film 144a later. Furthermore, when processing the sacrificial film 146a later, the sacrificial film 144a will be exposed. Therefore, a combination of films with a high etching selectivity between the sacrificial film 144a and the sacrificial film 146a is selected. Therefore, a film that can be used for the sacrificial film 146a can be selected depending on the etching conditions for the sacrificial film 144a and the sacrificial film 146a.

[0147] For example, when dry etching using a gas containing fluorine (also referred to as a fluorine-based gas) is used to etch the sacrificial film 146a, silicon, silicon nitride, silicon oxide, tungsten, titanium, molybdenum, tantalum, tantalum nitride, an alloy containing molybdenum and niobium, an alloy containing molybdenum and tungsten, or the like can be used for the sacrificial film 146a. Here, in the dry etching using the fluorine-based gas, examples of films that can have a large etching selectivity with respect to the sacrificial layer 146a (i.e., can slow down the etching rate) include metal oxide films such as IGZO and ITO, which can be used for the sacrificial film 144a.

[0148] However, the sacrificial film 146a is not limited to this, and can be selected from various materials depending on the etching conditions of the sacrificial film 144a and the etching conditions of the sacrificial film 146a. For example, it can be selected from the films that can be used for the sacrificial film 144a.

[0149] For example, an oxide film can be used as the sacrificial film 146a. Typically, an oxide film or an oxynitride film such as silicon oxide, silicon oxynitride, aluminum oxide, aluminum oxynitride, hafnium oxide, or hafnium oxynitride can also be used.

[0150] The sacrificial film 146a may be, for example, a nitride film, such as silicon nitride, aluminum nitride, hafnium nitride, titanium nitride, tantalum nitride, tungsten nitride, gallium nitride, or germanium nitride.

[0151] For example, it is preferable to use an inorganic insulating material such as aluminum oxide, hafnium oxide, or silicon oxide formed by an ALD method as the sacrificial film 144a, and to use a metal oxide containing indium such as indium gallium zinc oxide (In-Ga-Zn oxide, also referred to as IGZO) formed by a sputtering method as the sacrificial film 146a.

[0152] Alternatively, the sacrificial film 146a may be an organic film that can be used for the EL film 112Rf, etc. For example, the same organic film used for the EL film 112Rf, EL film 112Gf, or EL film 112Bf can be used for the sacrificial film 146a. Using such an organic film is preferable because it allows the same film-forming equipment to be used as for the EL film 112Rf, etc. Furthermore, the sacrificial film can be removed simultaneously when etching the EL film 112Rf, etc., using the sacrificial layer as a mask, thereby simplifying the process.

[0153] [Formation of Resist Mask 143a] Subsequently, resist masks 143a are formed on the sacrificial film 146a at positions overlapping the pixel electrode 111R and the connection electrode 111C (FIG. 6B).

[0154] The resist mask 143a can be made of a resist material containing a photosensitive resin, such as a positive resist material or a negative resist material.

[0155] Here, if the resist mask 143a is formed on the sacrificial film 144a without the sacrificial film 146a, there is a risk that the EL film 112Rf will be dissolved by the solvent of the resist material if there are defects such as pinholes in the sacrificial film 144a. By using the sacrificial film 146a, it is possible to prevent such problems from occurring.

[0156] In addition, if the sacrificial film 144a is a film that is less likely to have defects such as pinholes, or if the EL film 112Rf is made of a material that does not dissolve in the solvent of the resist material, it may be possible to form the resist mask 143a directly on the sacrificial film 144a without using the sacrificial film 146a.

[0157] [Etching of Sacrificial Film 146a] Subsequently, a portion of the sacrificial film 146a that is not covered by the resist mask 143a is removed by etching to form island-shaped or strip-shaped sacrificial layers 147a (FIG. 6C). At the same time, the sacrificial layers 147a are also formed on the connection electrodes 111C.

[0158] When etching the sacrificial film 146a, it is preferable to use etching conditions with a high selectivity so that the sacrificial film 144a is not removed by the etching. The sacrificial film 146a can be etched by wet etching or dry etching, but using dry etching can prevent the pattern of the sacrificial film 146a from shrinking.

[0159] [Removal of Resist Mask 143a] Subsequently, the resist mask 143a is removed (FIG. 6D).

[0160] The resist mask 143a can be removed by wet etching or dry etching. In particular, the resist mask 143a is preferably removed by dry etching (also called plasma ashing) using oxygen gas as an etching gas.

[0161] At this time, the resist mask 143a is removed in a state in which the EL film 112Rf is covered with the sacrificial film 144a, so that the influence on the EL film 112Rf is suppressed. In particular, if the EL film 112Rf comes into contact with oxygen, it may have an adverse effect on the electrical characteristics, so this is suitable for performing etching using oxygen gas, such as plasma ashing.

[0162] [Etching of Sacrificial Film 144a] Next, using the sacrificial layer 147a as a mask, a portion of the sacrificial film 144a that is not covered by the sacrificial layer 147a is removed by etching to form island-shaped or strip-shaped sacrificial layers 145a (FIG. 6E). At this time, the sacrificial layers 145a are also formed on the connection electrodes 111C.

[0163] The sacrificial film 144a can be etched by wet etching or dry etching, but dry etching is preferable because it can prevent the pattern from shrinking.

[0164] [Etching of EL film 112Rf] Subsequently, a portion of the EL film 112Rf that is not covered by the sacrificial layer 145a is removed by etching to form island-shaped or strip-shaped EL layers 112R (FIG. 6F). By etching the EL film 112Rf, the pixel electrodes 111G, 111B, and the upper surfaces of the insulating layer 132 are exposed.

[0165] In particular, it is preferable to use dry etching using an etching gas that does not contain oxygen as a main component for etching the EL film 112Rf. This makes it possible to suppress the deterioration of the EL film 112Rf and realize a highly reliable display device. As an etching gas that does not contain oxygen as a main component, for example, CF ４ , C ４ F ８ , SF ６ , CHF ３ , Cl ２ , H ２ O, BCl ３ , H ２ Alternatively, a noble gas such as He may be used. Also, a mixed gas of the above gas and a dilution gas that does not contain oxygen may be used as the etching gas.

[0166] The etching of the EL film 112Rf is not limited to the above, and may be dry etching using other gases or wet etching.

[0167] Furthermore, the etching rate can be increased by using an etching gas containing oxygen gas or dry etching using oxygen gas to etch the EL film 112Rf. Therefore, etching can be performed under low power conditions while maintaining a sufficiently high etching rate, thereby reducing damage caused by etching. Furthermore, problems such as adhesion of reaction products generated during etching can be suppressed. For example, an etching gas obtained by adding oxygen gas to the above-mentioned etching gas that does not contain oxygen as a main component can be used.

[0168] When the EL film 112Rf is etched, the insulating layer 132 is exposed. Therefore, it is preferable to use a film that is highly resistant to (hard to be etched by) the etching of the EL film 112Rf for the insulating layer 132. Note that when the EL film 112Rf is etched, the upper part of the insulating layer 132 may be etched, and the portion not covered by the EL layer 112R may become thinner.

[0169] Note that the sacrificial layer 147a may be etched at the same time as the EL film 112Rf is etched. Etching the EL film 112Rf and the sacrificial layer 147a by the same etching process is preferable because it simplifies the process and reduces the manufacturing cost of the display device.

[0170] [Formation of EL film 112Gf] Next, an EL film 112Gf, which will later become the EL layer 112G, is formed on the sacrificial layer 147a, the insulating layer 132, the pixel electrode 111G, and the pixel electrode 111B. At this time, similar to the EL film 112Rf, it is preferable not to provide the EL film 112Gf on the connection electrode 111C.

[0171] The above description of the EL film 112Rf can be used to describe the method of forming the EL film 112Gf.

[0172] [Formation of Sacrificial Film 144b] Next, the sacrificial film 144b is formed on the EL film 112Gf. The sacrificial film 144b can be formed by the same method as the sacrificial film 144a. In particular, it is preferable to use the same material for the sacrificial film 144b as for the sacrificial film 144a.

[0173] At the same time, a sacrificial film 144a is formed on the connection electrode 111C, covering the sacrificial layer 147a.

[0174] [Formation of Sacrificial Film 146b] Next, a sacrificial film 146b is formed on the sacrificial film 144b (FIG. 7A). The sacrificial film 146b can be formed by the same method as the sacrificial film 146a. In particular, it is preferable to use the same material for the sacrificial film 146b as the sacrificial film 146a.

[0175] [Formation of Resist Mask 143b] Subsequently, a resist mask 143b is formed on the sacrificial film 146b in a region overlapping with the pixel electrode 111G (FIG. 7B).

[0176] The resist mask 143b can be formed in the same manner as the resist mask 143a.

[0177] Here, since the connection electrode 111C is protected by the sacrificial layers 145a and 147a, the resist mask 143b does not need to be formed. Note that the resist mask 143b may be provided to cover the connection electrode 111C.

[0178] The resist mask 143b can be formed in the same manner as the resist mask 143a.

[0179] [Etching of Sacrificial Film 146b] Subsequently, a portion of the sacrificial film 146b that is not covered by the resist mask 143b is removed by etching to form island-shaped or strip-shaped sacrificial layers 147b (FIG. 7C). At the same time, the sacrificial film 146b on the connection electrode 111C is also removed by etching.

[0180] The above description of the sacrificial film 146a can be applied to the etching of the sacrificial film 146b.

[0181] [Removal of Resist Mask 143b] Next, the resist mask 143b is removed. The above description of the resist mask 143a can be applied to the removal of the resist mask 143b.

[0182] [Etching of Sacrificial Film 144b] Next, using the sacrificial layer 147b as a mask, a portion of the sacrificial film 144b that is not covered by the sacrificial layer 147b is removed by etching to form island-shaped or strip-shaped sacrificial layers 145b. At this time, the sacrificial film 144b on the connection electrode 111C is also removed by etching.

[0183] The above description of the sacrificial film 144a can be applied to the etching of the sacrificial film 144b.

[0184] [Etching of EL Film 112Gf] Subsequently, a part of the EL film 112Gf that is not covered with the sacrificial layer 145b is removed by etching to form island-shaped or strip-shaped EL layers 112G (FIG. 7D).

[0185] The above description of the EL film 112Rf can be applied to the etching of the EL film 112Gf.

[0186] At this time, the EL layer 112R and the connection electrode 111C are protected by the sacrificial layers 145a and 147a, and therefore can be prevented from being damaged in the etching process of the EL film 112Gf.

[0187] In this manner, the island-shaped or strip-shaped EL layers 112R and the island-shaped or strip-shaped EL layers 112G can be formed with high positional accuracy.

[0188] [Formation of EL Layer 112B] By performing the above steps on the EL film 112Bf (not shown), it is possible to form the island-shaped or strip-shaped EL layer 112B, the sacrificial layer 145c, and the sacrificial layer 147c (FIG. 7E).

[0189] That is, after the EL layer 112G is formed, the EL film 112Bf, the sacrificial film 144c, the sacrificial film 146c, and the resist mask 143c (none of which are shown) are formed in this order. The sacrificial film 146c is then etched to form the sacrificial layer 147c (not shown), and the resist mask 143c is then removed. The sacrificial film 144c is then etched to form the sacrificial layer 145c. The EL film 112Bf is then etched to form the island-shaped or strip-shaped EL layer 112B.

[0190] [Removal of Sacrificial Layers] Next, the sacrificial layers 147a, 147b, 147c, 145a, 145b, and 145c are removed to expose the upper surfaces of the EL layers 112R, 112G, and 112B ( FIG. 8A ). At the same time, the upper surface of the connection electrode 111C is also exposed.

[0191] It is preferable that the etching of sacrificial layers 147a, 147b, and 147c (hereinafter collectively referred to as sacrificial layers 147) and the etching of sacrificial layers 145a, 145b, and 145c (hereinafter collectively referred to as sacrificial layers 145) are performed in the same process.

[0192] The etching of the sacrificial layer 147 and the etching of the sacrificial layer 145 may be performed in different steps. In this case, the sacrificial layer 147 is etched first, and then the sacrificial layer 145 is etched.

[0193] Alternatively, the sacrificial layer 145 may be etched by an isotropic etch (eg, a wet etch) to lift off the sacrificial layer 147 .

[0194] The sacrificial layers 145 and 147 can be removed by wet etching or dry etching. At this time, it is preferable to use a method that causes as little damage as possible to the EL layers 112R, 112G, and 112B. In particular, it is preferable to use a wet etching method. For example, it is preferable to use wet etching using a tetramethylammonium hydroxide solution (TMAH), dilute hydrofluoric acid, oxalic acid, phosphoric acid, acetic acid, nitric acid, or a mixture thereof.

[0195] Alternatively, it is preferable to remove either or both of the sacrificial layer 145 and the sacrificial layer 147 by dissolving them in a solvent such as water or alcohol. Here, various alcohols such as ethyl alcohol, methyl alcohol, isopropyl alcohol (IPA), or glycerin can be used as the alcohol capable of dissolving the sacrificial layer 145 or the sacrificial layer 147.

[0196] After removing the sacrificial layers 145 and 147, it is preferable to perform drying treatment to remove water contained inside the EL layers 112R, 112G, and 112B and water adsorbed on their surfaces. For example, it is preferable to perform heat treatment in an inert gas atmosphere or a reduced-pressure atmosphere. The heat treatment can be performed at a substrate temperature of 50° C. or higher and 200° C. or lower, preferably 60° C. or higher and 150° C. or lower, and more preferably 70° C. or higher and 120° C. or lower. A reduced-pressure atmosphere is preferable because drying can be performed at a lower temperature.

[0197] In this manner, the EL layer 112R, the EL layer 112G, and the EL layer 112B can be separately produced.

[0198] [Formation of EL Layer 114] Subsequently, the EL layer 114 is formed to cover the EL layer 112R, the EL layer 112G, and the EL layer 112B.

[0199] The EL layer 114 can be formed by the same method as the EL film 112Rf, etc. When the EL layer 114 is formed by evaporation, it is preferable to form the EL layer 114 using a shielding mask so that the EL layer 114 is not formed on the connection electrode 111C.

[0200] [Formation of Common Electrode 113] Subsequently, the common electrode 113 is formed to cover the EL layer 114 and the connection electrode 111C (FIG. 8B).

[0201] The common electrode 113 can be formed by a film formation method such as evaporation or sputtering. Alternatively, a film formed by evaporation and a film formed by sputtering may be stacked. In this case, the common electrode 113 is preferably formed so as to encompass the region where the EL layer 114 is formed. That is, the edge of the EL layer 114 can overlap with the common electrode 113. The common electrode 113 is preferably formed using a shielding mask.

[0202] Moreover, the common electrode 113 is electrically connected to the connection electrode 111C outside the display area.

[0203] [Formation of Protective Layer 121] Next, the protective layer 121 is formed on the common electrode 113. The inorganic insulating film used for the protective layer 121 is preferably formed by sputtering, PECVD, or ALD. The ALD method is particularly preferred because it has excellent step coverage and is less likely to cause defects such as pinholes. Furthermore, the organic insulating film is preferably formed by inkjet printing, because it can form a uniform film in a desired area.

[0204] In this manner, the display device 100 shown in FIGS. 1B and 1C can be manufactured.

[0205] In the above description, the common electrode 113 and the EL layer 114 are formed to have different top surface shapes, but they may be formed in the same region.

[0206] 9A shows a schematic cross-sectional view of the structure after the sacrificial layer is removed. Subsequently, as shown in FIG. 9B, the EL layer 114 and the common electrode 113 are formed using the same mask or without a mask. This reduces manufacturing costs compared to when different masks are used.

[0207] 9B , the connection portion 130 has a configuration in which the EL layer 114 is sandwiched between the connection electrode 111C and the common electrode 113. In this case, it is preferable to use a material with as low an electrical resistance as possible for the EL layer 114. Alternatively, it is preferable to form the EL layer 114 as thin as possible to reduce the electrical resistance in the thickness direction of the EL layer 114. For example, by using an electron-injecting or hole-injecting material with a thickness of 1 nm to 5 nm, preferably 1 nm to 3 nm, for the EL layer 114, it may be possible to reduce the electrical resistance between the connection electrode 111C and the common electrode 113 to a negligible level.

[0208] 9C , a protective layer 121 is formed. At this time, as shown in Fig. 9C , it is preferable that the protective layer 121 is provided so as to cover the end portions of the common electrode 113 and the EL layer 114. This makes it possible to effectively prevent impurities such as water or oxygen from diffusing from the outside into the EL layer 114 and into the interface between the EL layer 114 and the common electrode 113.

[0209] This completes the description of the example of the method for manufacturing the display device.

[0210] [Modification] The following describes an example in which the configuration is partially different from that described above. Note that the same parts as those described above will be used hereinafter, and the description will be omitted.

[0211] 10A and 10B are schematic cross-sectional views of a display device 100A. The top view of the display device 100A is the same as that of FIG. 1A. FIG. 10A corresponds to a cross section in the X direction, and FIG. 8B corresponds to a cross section in the Y direction.

[0212] The display device 100A differs from the display device 100 in that it does not have the EL layer 114, which is a common layer.

[0213] The common electrode 113 is provided in contact with the upper surfaces of the EL layer 112R, the EL layer 112G, and the EL layer 112B. By not providing the EL layer 114, the light-emitting element 110R, the light-emitting element 110G, and the light-emitting element 110B can have completely different stacked structures, which increases the number of material options and increases the degree of freedom in design.

[0214] 10C is an example in which the EL layers and common electrodes 113 are processed continuously between light-emitting elements of the same color arranged in the Y direction without being separated from each other. That is, in the display device 100B, the EL layers and common electrodes 113 are processed so as to have a strip-like shape on the upper surface.

[0215] [Modification 2] A display device 100C shown in Figs. 11A and 11B differs from the display device 100 and the like mainly in that the configuration of the light-emitting elements is different.

[0216] The light-emitting element 110R has an optical adjustment layer 115R between the pixel electrode 111R and the EL layer 112R. The light-emitting element 110G has an optical adjustment layer 115G between the pixel electrode 111G and the EL layer 112G. The light-emitting element 110B has an optical adjustment layer 115B between the pixel electrode 111B and the EL layer 112B.

[0217] The optical adjustment layers 115R, 115G, and 115B each correspond to the conductive layer 111b illustrated in Figure 4A etc. In this case, the pixel electrodes 111R, 111G, and 111B each correspond to the conductive layer 111a.

[0218] Furthermore, optical adjustment layer 115R, optical adjustment layer 115G, and optical adjustment layer 115B are each translucent to visible light. Optical adjustment layer 115R, optical adjustment layer 115G, and optical adjustment layer 115B have different thicknesses, which allows the optical path length to be different for each light-emitting element.

[0219] Here, the pixel electrodes 111R, 111G, and 111B are made of conductive films that are reflective to visible light, and the common electrode 113 is made of a conductive film that is reflective and transparent to visible light. This allows each light-emitting element to have a so-called microcavity structure (a microresonator structure), which intensifies light of a specific wavelength. This makes it possible to realize a display device with improved color purity.

[0220] Each optical adjustment layer can be made of a conductive material that is transparent to visible light, such as indium oxide, indium tin oxide, indium zinc oxide, zinc oxide, zinc oxide containing gallium, indium tin oxide containing silicon, or indium zinc oxide containing silicon.

[0221] Each optical adjustment layer can be formed after forming the pixel electrodes 111R, 111G, and 111B and before forming the EL film 112Rf, etc. Each optical adjustment layer may use a conductive film having a different thickness, or may have a single-layer structure, a two-layer structure, a three-layer structure, etc., in order from thinnest to thinnest.

[0222] 11C is an example in which a strip-shaped EL layer extending in the Y direction and a common electrode 113 are applied to the display device 100C. Fig. 11C shows a cross section of two light-emitting elements 110G arranged side by side in the Y direction.

[0223] [Modification 3] A display device 100E shown in Figs. 12A and 12B differs from the display device 100C described above mainly in that it does not have an optical adjustment layer.

[0224] The display device 100E is an example in which a microcavity structure is realized by the thicknesses of the EL layers 112R, 112G, and 112B. With this configuration, there is no need to provide a separate optical adjustment layer, which simplifies the manufacturing process.

[0225] For example, in the display device 100E, the EL layer 112R of the light emitting element 110R that emits light with the longest wavelength is the thickest, and the EL layer 112B of the light emitting element 110B that emits light with the shortest wavelength is the thinnest. However, this is not limiting, and the thickness of each EL layer can be adjusted taking into consideration the wavelength of light emitted by each light emitting element, the optical characteristics of the layers that make up the light emitting element, the electrical characteristics of the light emitting element, and the like.

[0226] 12C is an example in which a strip-shaped EL layer extending in the Y direction and a common electrode 113 are applied to the display device 100E. Fig. 12C shows a cross section of two light-emitting elements 110G arranged side by side in the Y direction.

[0227] The above is a description of the modified example.

[0228] Although the EL layer 114 is used in the above-described modified examples 2 and 3, the EL layer 114 may not be provided.

[0229] At least a part of the configuration examples exemplified in this embodiment and the corresponding drawings can be combined as appropriate with other configuration examples or drawings.

[0230] This embodiment mode can be implemented by appropriately combining at least a part thereof with other embodiment modes described in this specification.

[0231] Embodiment 2 In this embodiment, a structural example of a display device according to one embodiment of the present invention will be described.

[0232] The display device of the present embodiment can be a high-resolution display device or a large-sized display device. Therefore, the display device of the present embodiment can be used in electronic devices having relatively large screens, such as television devices, desktop or notebook personal computers, computer monitors, digital signage, large game machines such as pachinko machines, as well as display units of digital cameras, digital video cameras, digital photo frames, mobile phones, portable game machines, smartphones, wristwatch-type terminals, tablet terminals, personal digital assistants, and sound reproducing devices.

[0233] [Display Device 400A] FIG. 13 shows a perspective view of the display device 400A, and FIG. 14A shows a cross-sectional view of the display device 400A.

[0234] The display device 400A has a configuration in which a substrate 452 and a substrate 451 are bonded together. In Fig. 13, the substrate 452 is clearly indicated by a dashed line.

[0235] The display device 400A includes a display portion 462, a circuit 464, wiring 465, and the like. Fig. 13 shows an example in which an IC 473 and an FPC 472 are mounted on the display device 400A. Therefore, the configuration shown in Fig. 13 can also be considered as a display module including the display device 400A, an IC (integrated circuit), and an FPC.

[0236] The circuit 464 can be, for example, a scanning line driver circuit.

[0237] The wiring 465 has a function of supplying signals and power to the display portion 462 and the circuit 464. The signals and power are input to the wiring 465 from the outside via the FPC 472 or input to the wiring 465 from the IC 473.

[0238] 13 shows an example in which an IC 473 is provided on a substrate 451 by a chip-on-glass (COG) method, a chip-on-film (COF) method, or the like. The IC 473 can be, for example, an IC having a scanning line driver circuit or a signal line driver circuit. The display device 400A and the display module may not include an IC. Alternatively, the IC may be mounted on an FPC by a COF method or the like.

[0239] FIG. 14A shows an example of a cross section of the display device 400A, in which a part of a region including an FPC 472, a part of a circuit 464, a part of a display portion 462, and a part of a region including an end portion are cut away.

[0240] The display device 400A shown in Figure 14A has, between a substrate 451 and a substrate 452, a transistor 201, a transistor 205, a light-emitting element 430a that emits red light, a light-emitting element 430b that emits green light, and a light-emitting element 430c that emits blue light.

[0241] The light-emitting element described as an example in Embodiment 1 can be applied to the light-emitting element 430a, the light-emitting element 430b, and the light-emitting element 430c.

[0242] Here, when a pixel of a display device has three types of subpixels having light-emitting elements that emit different colors, the three subpixels include subpixels of three colors of red (R), green (G), and blue (B), or subpixels of three colors of yellow (Y), cyan (C), and magenta (M), etc. When a pixel of a display device has four subpixels, the four subpixels include subpixels of four colors of R, G, B, and white (W), or subpixels of four colors of R, G, B, and Y, etc.

[0243] The protective layer 416 and the substrate 452 are bonded via an adhesive layer 442. A solid sealing structure, a hollow sealing structure, or the like can be applied to seal the light-emitting element. In FIG. 14A , a space 443 surrounded by the substrate 452, the adhesive layer 442, and the substrate 451 is filled with an inert gas (such as nitrogen or argon), and a hollow sealing structure is applied. The adhesive layer 442 may be provided so as to overlap the light-emitting element. Furthermore, the space 443 surrounded by the substrate 452, the adhesive layer 442, and the substrate 451 may be filled with a resin different from the adhesive layer 442.

[0244] The light-emitting element 430a, the light-emitting element 430b, and the light-emitting element 430c each have an optical adjustment layer between the pixel electrode and the EL layer. The light-emitting element 430a has an optical adjustment layer 426a, the light-emitting element 430b has an optical adjustment layer 426b, and the light-emitting element 430c has an optical adjustment layer 426c. For details of the light-emitting elements, refer to Embodiment 1.

[0245] The pixel electrode 411 a , the pixel electrode 411 b , and the pixel electrode 411 c are each connected to a conductive layer 222 b of the transistor 205 through an opening provided in the insulating layer 214 .

[0246] The pixel electrodes and the ends of the optical adjustment layer are covered with insulating layers 421 and 422. The insulating layer 421 contains an organic resin, and the insulating layer 422 contains an inorganic insulating film. The pixel electrodes contain a material that reflects visible light, and the counter electrode contains a material that transmits visible light.

[0247] Light emitted from the light-emitting element is emitted toward the substrate 452. The substrate 452 is preferably made of a material that is highly transparent to visible light.

[0248] The transistor 201 and the transistor 205 are both formed over a substrate 451. These transistors can be manufactured using the same material and through the same process.

[0249] An insulating layer 211, an insulating layer 213, an insulating layer 215, and an insulating layer 214 are provided over the substrate 451 in this order. A part of the insulating layer 211 functions as a gate insulating layer of each transistor. A part of the insulating layer 213 functions as a gate insulating layer of each transistor. The insulating layer 215 is provided to cover the transistor. The insulating layer 214 is provided to cover the transistor and functions as a planarization layer. Note that the number of gate insulating layers and the number of insulating layers covering the transistors are not limited, and each may be a single layer or two or more layers.

[0250] At least one insulating layer covering the transistor is preferably made of a material that is resistant to the diffusion of impurities such as water and hydrogen. This allows the insulating layer to function as a barrier layer. With this structure, it is possible to effectively prevent impurities from diffusing into the transistor from the outside, thereby improving the reliability of the display device.

[0251] It is preferable to use an inorganic insulating film for each of the insulating layers 211, 213, and 215. Examples of the inorganic insulating film that can be used include a silicon nitride film, a silicon oxynitride film, a silicon oxide film, a silicon nitride oxide film, an aluminum oxide film, and an aluminum nitride film. Alternatively, a hafnium oxide film, an yttrium oxide film, a zirconium oxide film, a gallium oxide film, a tantalum oxide film, a magnesium oxide film, a lanthanum oxide film, a cerium oxide film, and a neodymium oxide film may also be used. Two or more of the above-described inorganic insulating films may be stacked.

[0252] Here, organic insulating films often have lower barrier properties than inorganic insulating films. Therefore, it is preferable that the organic insulating film has an opening near the edge of the display device 400A. This makes it possible to prevent impurities from entering from the edge of the display device 400A through the organic insulating film. Alternatively, the organic insulating film may be formed so that the edge of the organic insulating film is located inside the edge of the display device 400A, so that the organic insulating film is not exposed at the edge of the display device 400A.

[0253] An organic insulating film is suitable for the insulating layer 214 that functions as a planarizing layer. Materials that can be used for the organic insulating film include acrylic resin, polyimide resin, epoxy resin, polyamide resin, polyimideamide resin, siloxane resin, benzocyclobutene resin, phenol resin, and precursors of these resins.

[0254] 14A , an opening is formed in insulating layer 214. This makes it possible to prevent impurities from entering display unit 462 from the outside through insulating layer 214, even when an organic insulating film is used for insulating layer 214. This makes it possible to improve the reliability of display device 400A.

[0255] The transistor 201 and the transistor 205 each include a conductive layer 221 that functions as a gate, an insulating layer 211 that functions as a gate insulating layer, conductive layers 222a and 222b that function as a source and a drain, a semiconductor layer 231, an insulating layer 213 that functions as a gate insulating layer, and a conductive layer 223 that functions as a gate. Here, the same hatching pattern is applied to multiple layers obtained by processing the same conductive film. 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.

[0256] The structure of the transistor included in the display device of this embodiment is not particularly limited. For example, a planar transistor, a staggered transistor, an inverted staggered transistor, or the like can be used. Furthermore, either a top-gate transistor or a bottom-gate transistor structure may be used. Alternatively, gates may be provided above and below a semiconductor layer in which a channel is formed.

[0257] The transistor 201 and the transistor 205 have a structure in which a semiconductor layer in which a channel is formed is sandwiched between two gates. The two gates may be connected and the same signal may be supplied to drive the transistor. Alternatively, the threshold voltage of the transistor may be controlled by applying a potential for controlling the threshold voltage to one of the two gates and a potential for driving to the other.

[0258] The crystallinity of a semiconductor material used for a semiconductor layer of a transistor is not particularly limited, and any of an amorphous semiconductor, a single-crystal semiconductor, and a semiconductor having crystallinity other than single crystal (a microcrystalline semiconductor, a polycrystalline semiconductor, or a semiconductor having a crystalline region in part) may be used. The use of a single-crystal semiconductor or a crystalline semiconductor is preferable because it can suppress deterioration of transistor characteristics.

[0259] The semiconductor layer of the transistor preferably includes a metal oxide (also referred to as an oxide semiconductor). That is, the display device of this embodiment preferably includes a transistor using a metal oxide for a channel formation region (hereinafter referred to as an OS transistor).

[0260] The band gap of the metal oxide used for the semiconductor layer of the transistor is preferably 2 eV or more, more preferably 2.5 eV or more. Use of a metal oxide with a wide band gap can reduce the off-state current of the OS transistor.

[0261] The metal oxide preferably contains at least indium or zinc, and more preferably contains indium and zinc. For example, the metal oxide preferably contains indium, M (wherein M is one or more selected from gallium, aluminum, yttrium, tin, silicon, boron, copper, vanadium, beryllium, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, magnesium, and cobalt), and zinc. In particular, M is preferably one or more selected from gallium, aluminum, yttrium, and tin, and more preferably gallium. Note that a metal oxide containing indium, M, and zinc may be referred to as an In-M-Zn oxide hereinafter.

[0262] When the metal oxide is an In-M-Zn oxide, the atomic ratio of In in the In-M-Zn oxide is preferably equal to or greater than the atomic ratio of M. Examples of atomic ratios of metal elements in such In-M-Zn oxides include a composition in which In:M:Zn=1:1:1 or thereabouts, a composition in which In:M:Zn=1:1:1.2 or thereabouts, a composition in which In:M:Zn=2:1:3 or thereabouts, a composition in which In:M:Zn=3:1:2 or thereabouts, a composition in which In:M:Zn=4:2:3 or thereabouts, a composition in which In:M:Zn=4:2:4.1 or thereabouts, a composition in which In:M:Zn=5:1:3 or thereabouts, a composition in which In:M:Zn=5:1:6 or thereabouts, a composition in which In:M:Zn=5:1:7 or thereabouts, a composition in which In:M:Zn=5:1:8 or thereabouts, a composition in which In:M:Zn=6:1:6 or thereabouts, and a composition in which In:M:Zn=5:2:5 or thereabouts. Note that the term "nearby composition" includes a range of ±30% of the desired atomic ratio. By increasing the atomic ratio of indium in the metal oxide, the on-state current, field-effect mobility, and the like of the transistor can be increased.

[0263] For example, when describing a composition having an atomic ratio of In:Ga:Zn=4:2:3 or thereabout, this includes a case where, when In is taken as 4, Ga is 1 or more and 3 or less, and Zn is 2 or more and 4 or less. Furthermore, when describing a composition having an atomic ratio of In:Ga:Zn=5:1:6 or thereabout, this includes a case where, when In is taken as 5, Ga is more than 0.1 and 2 or less, and Zn is 5 or more and 7 or less. Furthermore, when describing a composition having an atomic ratio of In:Ga:Zn=1:1:1 or thereabout, this includes a case where, when In is taken as 1, Ga is more than 0.1 and 2 or less, and Zn is more than 0.1 and 2 or less.

[0264] Furthermore, the atomic ratio of In in the In-M-Zn oxide may be less than the atomic ratio of M. Examples of atomic ratios of metal elements in such an In-M-Zn oxide include a composition of In:M:Zn=1:3:2 or thereabouts, a composition of In:M:Zn=1:3:3 or thereabouts, and a composition of In:M:Zn=1:3:4 or thereabouts. Increasing the atomic ratio of M in the metal oxide can increase the band gap of the In-M-Zn oxide and improve its resistance to a negative bias stress test due to light irradiation. Specifically, the amount of change in threshold voltage or the amount of change in shift voltage (Vsh) measured in a negative bias temperature illumination stress (NBTIS) test of a transistor can be reduced. The shift voltage (Vsh) is defined as the Vg at which the tangent to the maximum slope of the drain current (Id)-gate voltage (Vg) curve of the transistor intersects with the line of Id=1 pA.

[0265] Alternatively, the semiconductor layer of the transistor may contain silicon, such as amorphous silicon or crystalline silicon (such as low-temperature polysilicon or single-crystal silicon).

[0266] Alternatively, the semiconductor layer of the transistor may include a layered material that functions as a semiconductor. A layered material is a general term for a group of materials having a layered crystal structure. A layered crystal structure is a structure in which layers formed by covalent or ionic bonds are stacked via bonds weaker than covalent or ionic bonds, such as van der Waals forces. A layered material has high electrical conductivity within a unit layer, i.e., high two-dimensional electrical conductivity. By using a material that functions as a semiconductor and has high two-dimensional electrical conductivity in the channel formation region, a transistor with a large on-state current can be provided.

[0267] Examples of the layered material include graphene, silicene, and chalcogenides. Chalcogenides are compounds containing chalcogen (an element belonging to Group 16). Examples of chalcogenides include transition metal chalcogenides and Group 13 chalcogenides. Specific examples of transition metal chalcogenides that can be used as semiconductor layers of transistors include molybdenum sulfide (typically MoS ２ ), molybdenum selenide (typically MoSe ２ ), molybdenum telluride (typically MoTe ２ ), tungsten sulfide (typically WS ２ ), tungsten selenide (typically WSe ２ ), tungsten tellurium (typically WTe ２ ), hafnium sulfide (typically HfS ２ ), hafnium selenide (typically HfSe ２ ), zirconium sulfide (typically ZrS ２ ), zirconium selenide (typically ZrSe ２ ) etc.

[0268] The transistors included in the circuit 464 may have the same structure as or different from the transistors included in the display portion 462. The transistors included in the circuit 464 may all have the same structure or may have two or more types of structures. Similarly, the transistors included in the display portion 462 may all have the same structure or may have two or more types of structures.

[0269] A connection portion 204 is provided in a region of the substrate 451 where the substrate 452 does not overlap. In the connection portion 204, a wiring 465 is electrically connected to an FPC 472 via a conductive layer 466 and a connection layer 242. The conductive layer 466 has an example of a stacked structure of a conductive film obtained by processing the same conductive film as the pixel electrode and a conductive film obtained by processing the same conductive film as the optical adjustment layer. The conductive layer 466 is exposed on the top surface of the connection portion 204. This allows the connection portion 204 and the FPC 472 to be electrically connected via the connection layer 242.

[0270] It is preferable to provide a light-shielding layer 417 on the surface of substrate 452 facing substrate 451. In addition, various optical members can be arranged on the outside of substrate 452. Examples of optical members include a polarizing plate, a retardation plate, a light diffusion layer (such as a diffusion film), an anti-reflection layer, and a light-collecting film. In addition, an antistatic film that suppresses the adhesion of dust, a water-repellent film that makes it difficult for dirt to adhere, a hard coat film that suppresses the occurrence of scratches during use, an impact absorbing layer, etc. may be arranged on the outside of substrate 452.

[0271] By providing the protective layer 416 that covers the light-emitting element, impurities such as water can be prevented from entering the light-emitting element, and the reliability of the light-emitting element can be improved.

[0272] In a region 228 near the edge of the display device 400A, it is preferable that the insulating layer 215 and the protective layer 416 contact each other through the opening in the insulating layer 214. In particular, it is preferable that the inorganic insulating film of the insulating layer 215 and the inorganic insulating film of the protective layer 416 contact each other. This makes it possible to prevent impurities from entering the display unit 462 from the outside via the organic insulating film. Therefore, it is possible to improve the reliability of the display device 400A.

[0273] 14B shows an example of a three-layer structure of the protective layer 416. In Fig. 14B, the protective layer 416 has 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.

[0274] The inorganic insulating layer 416a and the inorganic insulating layer 416c extend outward beyond the edge of the organic insulating layer 416b and are in contact with each other. In an area where no common electrode is provided, the inorganic insulating layer 416a and the insulating layer 422 are in contact with each other. The insulating layer 422 is in contact with the insulating layer 215 (inorganic insulating layer) through an opening in the insulating layer 214 (organic insulating layer). This allows the insulating layer 215 and the protective layer 416 to surround the light-emitting element, thereby improving the reliability of the light-emitting element.

[0275] In this way, the protective layer 416 may have a laminated structure of an organic insulating film and an inorganic insulating film, in which case it is preferable that the inorganic insulating film extend further outward than the organic insulating film.

[0276] The substrate 451 and the substrate 452 can each be made of glass, quartz, ceramic, sapphire, resin, metal, alloy, semiconductor, or the like. A material that transmits light is used for the substrate on the side from which light from the light-emitting element is extracted. Using a flexible material for the substrate 451 and the substrate 452 can increase the flexibility of the display device. Alternatively, a polarizing plate may be used for the substrate 451 or the substrate 452.

[0277] The substrates 451 and 452 can be made of polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyacrylonitrile resin, acrylic resin, polyimide resin, polymethyl methacrylate resin, polycarbonate (PC) resin, polyethersulfone (PES) resin, polyamide resin (nylon, aramid, etc.), polysiloxane resin, cycloolefin resin, polystyrene resin, polyamideimide resin, polyurethane resin, polyvinyl chloride resin, polyvinylidene chloride resin, polypropylene resin, polytetrafluoroethylene (PTFE) resin, ABS resin, cellulose nanofiber, etc. One or both of the substrates 451 and 452 may be made of glass having a thickness sufficient to provide flexibility.

[0278] When a circularly polarizing plate is superimposed on a display device, it is preferable that the display device has a substrate with high optical isotropy. A substrate with high optical isotropy has small birefringence (or a small amount of birefringence).

[0279] The absolute value of the retardation (phase difference) of a substrate having high optical isotropy is preferably 30 nm or less, more preferably 20 nm or less, and even more preferably 10 nm or less.

[0280] Examples of films with high optical isotropy include triacetyl cellulose (TAC, also known as cellulose triacetate) films, cycloolefin polymer (COP) films, cycloolefin copolymer (COC) films, and acrylic films.

[0281] Furthermore, when a film is used as a substrate, the film may absorb water, causing deformation such as wrinkles in the display panel. Therefore, it is preferable to use a film with low water absorption for the substrate. For example, it is preferable to use a film with a water absorption rate of 1% or less, more preferably 0.1% or less, and even more preferably 0.01% or less.

[0282] The adhesive layer can be made of various curable adhesives, such as photo-curable adhesives (e.g., ultraviolet curable), reactive curable adhesives, thermosetting adhesives, and anaerobic adhesives. Examples of such adhesives include epoxy resin, acrylic resin, silicone resin, phenolic resin, polyimide resin, imide resin, PVC (polyvinyl chloride) resin, PVB (polyvinyl butyral) resin, and EVA (ethylene vinyl acetate) resin. Materials with low moisture permeability, such as epoxy resin, are particularly preferred. Two-component resins may also be used. Adhesive sheets, etc., may also be used.

[0283] The connection layer 242 may be an anisotropic conductive film (ACF), an anisotropic conductive paste (ACP), or the like.

[0284] Materials that can be used for conductive layers such as the gate, source, and drain of a transistor, as well as various wirings and electrodes that constitute a display device include metals such as aluminum, titanium, chromium, nickel, copper, yttrium, zirconium, molybdenum, silver, tantalum, and tungsten, and alloys containing these metals as main components, etc. Films containing these materials can be used as a single layer or a stacked layer structure.

[0285] Examples of light-transmitting conductive materials include conductive oxides such as indium oxide, indium tin oxide, indium zinc oxide, zinc oxide, and zinc oxide containing gallium, or graphene. Alternatively, metal materials such as gold, silver, platinum, magnesium, nickel, tungsten, chromium, molybdenum, iron, cobalt, copper, palladium, and titanium, or alloy materials containing such metal materials, can be used. Alternatively, nitrides of such metal materials (e.g., titanium nitride) can be used. When using metal materials or alloy materials (or their nitrides), it is preferable to thin them sufficiently to ensure light-transmitting properties. A stacked film of the above materials can also be used as the conductive layer. For example, a stacked film of an alloy of silver and magnesium and indium tin oxide is preferable because it can enhance conductivity. These materials can also be used for conductive layers such as various wirings and electrodes constituting a display device, and for conductive layers (conductive layers functioning as pixel electrodes or common electrodes) of light-emitting elements.

[0286] Examples of insulating materials that can be used for each insulating layer include resins such as acrylic resin and epoxy resin, and inorganic insulating materials such as silicon oxide, silicon oxynitride, silicon nitride oxide, silicon nitride, and aluminum oxide.

[0287] [Display Device 400B] Fig. 15A shows a cross-sectional view of the display device 400B. The perspective view of the display device 400B is similar to that of the display device 400A shown in Fig. 13. Fig. 15A shows an example of a cross-section of the display device 400B, where a portion of a region including the FPC 472, a portion of the circuit 464, and a portion of the display unit 462 are cut away. Fig. 15A shows an example of a cross-section of the display unit 462, particularly, where a region including the light-emitting element 430b that emits green light and the light-emitting element 430c that emits blue light is cut away. Note that descriptions of portions similar to those of the display device 400A may be omitted.

[0288] A display device 400B shown in FIG. 15A includes the transistor 202, the transistor 210, the light-emitting element 430b, the light-emitting element 430c, and the like between a substrate 453 and a substrate 454.

[0289] The substrate 454 and the protective layer 416 are bonded together via an adhesive layer 442. The adhesive layer 442 is provided to overlap the light-emitting element 430b and the light-emitting element 430c, respectively, and a solid sealing structure is applied to the display device 400B.

[0290] The substrate 453 and the insulating layer 212 are bonded together by an adhesive layer 455 .

[0291] The display device 400B is manufactured by first bonding a fabrication substrate provided with the insulating layer 212, the transistors, the light-emitting elements, and the like to a substrate 454 provided with a light-shielding layer 417 with an adhesive layer 442. The fabrication substrate is then peeled off, and a substrate 453 is attached to the exposed surface, thereby transferring each component formed on the fabrication substrate to the substrate 453. The substrate 453 and the substrate 454 are preferably flexible. This can increase the flexibility of the display device 400B.

[0292] The insulating layer 212 can be formed using the inorganic insulating film that can be used for the insulating layer 211, the insulating layer 213, and the insulating layer 215, respectively.

[0293] The pixel electrode is connected to a conductive layer 222b of the transistor 210 through an opening provided in the insulating layer 214. The transistor 210 has a function of controlling driving of a light-emitting element.

[0294] The edge of the pixel electrode is covered with an insulating layer 421 and an insulating layer 422 .

[0295] Light emitted from the light-emitting elements 430b and 430c is emitted toward the substrate 454. The substrate 454 is preferably made of a material that is highly transparent to visible light.

[0296] A connection portion 204 is provided in a region of the substrate 453 where the substrate 454 does not overlap. In the connection portion 204, a wiring 465 is electrically connected to an FPC 472 via a conductive layer 466 and a connection layer 242. The conductive layer 466 can be obtained by processing the same conductive film as the pixel electrode. This allows the connection portion 204 and the FPC 472 to be electrically connected via the connection layer 242.

[0297] The transistor 202 and the transistor 210 each include a conductive layer 221 functioning as a gate, an insulating layer 211 functioning as a gate insulating layer, a semiconductor layer 231 including a channel formation region 231i and a pair of low-resistance regions 231n, a conductive layer 222a connected to one of the pair of low-resistance regions 231n, a conductive layer 222b connected to the other of the pair of low-resistance regions 231n, an insulating layer 225 functioning as a gate insulating layer, a conductive layer 223 functioning as a gate, and an insulating layer 215 covering the conductive layer 223. The insulating layer 211 is located between the conductive layer 221 and the channel formation region 231i. The insulating layer 225 is located between the conductive layer 223 and the channel formation region 231i.

[0298] The conductive layer 222a and the conductive layer 222b are each connected to the low-resistance region 231n through an opening provided in the insulating layer 215. One of the conductive layer 222a and the conductive layer 222b functions as a source, and the other functions as a drain.

[0299] 15A shows an example in which the top surface and side surfaces of the semiconductor layer are covered with an insulating layer 225. The conductive layer 222a and the conductive layer 222b are connected to the low-resistance region 231n through openings provided in the insulating layer 225 and the insulating layer 215, respectively.

[0300] 15B , the insulating layer 225 overlaps with the channel formation region 231i of the semiconductor layer 231 but does not overlap with the low-resistance region 231n. For example, the structure shown in FIG. 15B can be manufactured by processing the insulating layer 225 using the conductive layer 223 as a mask. In FIG. 15B , the insulating layer 215 is provided to cover the insulating layer 225 and the conductive layer 223, and the conductive layer 222a and the conductive layer 222b are each connected to the low-resistance region 231n through openings in the insulating layer 215. Furthermore, an insulating layer 218 may be provided to cover the transistor.

[0301] At least a part of the configuration examples exemplified in this embodiment and the corresponding drawings can be combined as appropriate with other configuration examples or drawings.

[0302] This embodiment mode can be implemented by appropriately combining at least a part thereof with other embodiment modes described in this specification.

[0303] Embodiment 3 In this embodiment, a light-emitting element (also referred to as a light-emitting device) that can be used for a display device that is one embodiment of the present invention will be described.

[0304] In this specification, etc., a device fabricated using a metal mask or an FMM (fine metal mask, high-resolution metal mask) may be referred to as a device with an MM (metal mask) structure. Also, in this specification, etc., a device fabricated without using a metal mask or an FMM may be referred to as a device with an MML (metal maskless) structure.

[0305] In this specification and the like, a structure in which different light-emitting layers are formed or different light-emitting layers are painted for each color light-emitting device (here, blue (B), green (G), and red (R)) may be referred to as an SBS (Side By Side) structure. In this specification and the like, a light-emitting device that can emit white light may be referred to as a white light-emitting device. In addition, a white light-emitting device can be combined with a colored layer (for example, a color filter) to realize a full-color display device.

[0306] Furthermore, light-emitting devices can be broadly divided into single structures and tandem structures. A single-structure device has one light-emitting unit between a pair of electrodes, and the light-emitting unit preferably includes one or more light-emitting layers. To obtain white light emission with a single structure, light-emitting layers can be selected so that the light emitted from each of the two or more light-emitting layers has a complementary color relationship. For example, by making the emission color of the first light-emitting layer and the emission color of the second light-emitting layer complementary to each other, a configuration in which the entire light-emitting device emits white light can be obtained. The same applies to light-emitting devices having three or more light-emitting layers.

[0307] A tandem-structure device preferably has two or more light-emitting units between a pair of electrodes, with each light-emitting unit preferably including one or more light-emitting layers. By using light-emitting layers that emit light of the same color in each light-emitting unit, the luminance per given current can be increased, and the device can be made more reliable than a single-structure light-emitting device. To obtain white light emission in a tandem structure, the device can be configured to combine light from the light-emitting layers of multiple light-emitting units to obtain white light. The combination of light-emitting colors that can produce white light is the same as in the single-structure configuration. In a tandem-structure device, it is preferable to provide an intermediate layer, such as a charge-generating layer, between the multiple light-emitting units.

[0308] Furthermore, when comparing the above-described white light-emitting device (single structure or tandem structure) with a light-emitting device having an SBS structure, the light-emitting device having an SBS structure can reduce power consumption compared to the white light-emitting device. If it is desired to reduce power consumption, it is preferable to use a light-emitting device having an SBS structure. On the other hand, the manufacturing process of a white light-emitting device is simpler than that of a light-emitting device having an SBS structure, and therefore the manufacturing cost can be reduced or the manufacturing yield can be increased, making it preferable.

[0309] 16A , the light-emitting element has an EL layer 23 between a pair of electrodes (a lower electrode 21 and an upper electrode 25). The EL layer 23 can be composed of a plurality of layers such as a layer 4420, a light-emitting layer 4411, and a layer 4430. The layer 4420 can have, for example, a layer containing a substance with high electron injection properties (electron injection layer) and a layer containing a substance with high electron transport properties (electron transport layer). The light-emitting layer 4411 contains, for example, a light-emitting compound. The layer 4430 can have, for example, a layer containing a substance with high hole injection properties (hole injection layer) and a layer containing a substance with high hole transport properties (hole transport layer).

[0310] A structure having the layer 4420, the light-emitting layer 4411, and the layer 4430 provided between a pair of electrodes can function as a single light-emitting unit, and the structure of FIG. 16A is referred to as a single structure in this specification.

[0311] 16B shows a modified example of the EL layer 23 included in the light-emitting element 20 shown in Fig. 16A. Specifically, the light-emitting element 20 shown in Fig. 16B includes a layer 4430-1 on the lower electrode 21, a layer 4430-2 on the layer 4430-1, a light-emitting layer 4411 on the layer 4430-2, a layer 4420-1 on the light-emitting layer 4411, a layer 4420-2 on the layer 4420-1, and an upper electrode 25 on the layer 4420-2. For example, when the lower electrode 21 is an anode and the upper electrode 25 is a cathode, the layer 4430-1 functions as a hole injection layer, the layer 4430-2 functions as a hole transport layer, the layer 4420-1 functions as an electron transport layer, and the layer 4420-2 functions as an electron injection layer. Alternatively, when the lower electrode 21 is used as a cathode and the upper electrode 25 is used as an anode, the layer 4430-1 functions as an electron injection layer, the layer 4430-2 functions as an electron transport layer, the layer 4420-1 functions as a hole transport layer, and the layer 4420-2 functions as a hole injection layer. By using such a layer structure, it is possible to efficiently inject carriers into the light-emitting layer 4411 and increase the efficiency of carrier recombination in the light-emitting layer 4411.

[0312] Note that a configuration in which a plurality of light-emitting layers (light-emitting layers 4411, 4412, and 4413) are provided between the layer 4420 and the layer 4430 as shown in FIG. 16C is also a variation of the single structure.

[0313] 16D, a configuration in which a plurality of light-emitting units (EL layers 23a, 23b) are connected in series via an intermediate layer (charge generating layer) 4440 is referred to as a tandem structure in this specification. Note that although the configuration shown in FIG. 16D is referred to as a tandem structure in this specification and the like, this is not limiting, and for example, the tandem structure may also be referred to as a stack structure. Note that by using a tandem structure, a light-emitting element capable of emitting light with high brightness can be obtained.

[0314] 16D , the same light-emitting material may be used for the light-emitting layer 4411 and the light-emitting layer 4412. Alternatively, light-emitting materials that emit different light may be used for the light-emitting layer 4411 and the light-emitting layer 4412. When the light emitted by the light-emitting layer 4411 and the light emitted by the light-emitting layer 4412 are complementary colors, white light emission is obtained.

[0315] 16C and 16D, the layer 4420 and the layer 4430 may have a laminated structure consisting of two or more layers, as shown in FIG. 16B.

[0316] Furthermore, a structure in which each light-emitting element produces a different emission color (here, blue (B), green (G), and red (R)) is sometimes called an SBS (Side By Side) structure.

[0317] The light-emitting element can emit light in red, green, blue, cyan, magenta, yellow, white, or the like, depending on the material of the EL layer 23. Furthermore, the color purity can be further improved by providing the light-emitting element with a microcavity structure.

[0318] A light-emitting element that emits white light preferably has a structure in which two or more types of light-emitting materials are contained in the light-emitting layer. To obtain white light emission, light-emitting materials may be selected such that the respective emissions of the two or more light-emitting materials have a complementary color relationship. For example, by making the emission color of the first light-emitting layer and the emission color of the second light-emitting layer complementary to each other, a light-emitting element that emits white light as a whole can be obtained. The same applies to a light-emitting element having three or more light-emitting layers.

[0319] The light-emitting layer preferably contains two or more light-emitting materials that emit light of R (red), G (green), B (blue), Y (yellow), O (orange), etc. Alternatively, it is preferable that the light-emitting layer contains two or more light-emitting materials, and the light emitted by each of the light-emitting materials contains spectral components of two or more colors of R, G, and B.

[0320] Here, a specific example of the configuration of the light-emitting element will be described.

[0321] The light-emitting element has at least a light-emitting layer. The light-emitting element may further have, as a layer other than the light-emitting layer, a layer containing a substance having a high hole-injecting property, a substance having a high hole-transporting property, a hole-blocking material, a substance having a high electron-transporting property, an electron-blocking material, a substance having a high electron-injecting property, a bipolar substance (a substance having a high electron-transporting property and a high hole-transporting property), or the like.

[0322] The light-emitting device can be made of either a low-molecular-weight compound or a high-molecular-weight compound, and may contain an inorganic compound. The layers constituting the light-emitting device can be formed by a method such as vapor deposition (including vacuum vapor deposition), transfer, printing, inkjet printing, or coating.

[0323] For example, the light-emitting device may have, in addition to the light-emitting layer, one or more of a hole-injection layer, a hole-transport layer, a hole-blocking layer, an electron-blocking layer, an electron-transport layer, and an electron-injection layer.

[0324] The hole injection layer is a layer that injects holes from the anode into the hole transport layer and contains a material with high hole injection properties, such as an aromatic amine compound and a composite material containing a hole transport material and an acceptor material (electron acceptor material).

[0325] The hole transport layer is a layer that transports holes injected from the anode by the hole injection layer to the light emitting layer. The hole transport layer is a layer that contains a hole transport material. The hole transport material is a material having a concentration of 1×10 −６ cm ２ A substance having a hole mobility of 1 / Vs or more is preferred. Note that other substances can also be used as long as they have a higher hole transporting property than electron transporting property. As the hole transporting material, a material having a high hole transporting property, such as a π-electron-rich heteroaromatic compound (e.g., a carbazole derivative, a thiophene derivative, a furan derivative, etc.) or an aromatic amine (a compound having an aromatic amine skeleton), is preferred.

[0326] The electron transport layer is a layer that transports electrons injected from the cathode by the electron injection layer to the light emitting layer. The electron transport layer is a layer that contains an electron transporting material. The electron transporting material is a material having a molecular weight of 1×10 −６ cm ２A substance having an electron mobility of 1 / Vs or more is preferred. Note that other substances can also be used as long as they have a higher electron transporting property than holes. Examples of electron-transporting materials that can be used include metal complexes having a quinoline skeleton, metal complexes having a benzoquinoline skeleton, metal complexes having an oxazole skeleton, and metal complexes having a thiazole skeleton, as well as oxadiazole derivatives, triazole derivatives, imidazole derivatives, oxazole derivatives, thiazole derivatives, phenanthroline derivatives, quinoline derivatives having a quinoline ligand, benzoquinoline derivatives, quinoxaline derivatives, dibenzoquinoxaline derivatives, pyridine derivatives, bipyridine derivatives, pyrimidine derivatives, and other π-electron-deficient heteroaromatic compounds including nitrogen-containing heteroaromatic compounds.

[0327] The electron injection layer is a layer that injects electrons from the cathode to the electron transport layer and contains a material with high electron injection properties. Examples of the material with high electron injection properties include alkali metals, alkaline earth metals, and compounds thereof. Examples of the material with high electron injection properties include a composite material containing an electron transport material and a donor material (electron donor material).

[0328] The electron injection layer may be formed of, for example, lithium, cesium, lithium fluoride (LiF), cesium fluoride (CsF), calcium fluoride (CaF ２ ), 8-(quinolinolato)lithium (abbreviation: Liq), 2-(2-pyridyl)phenolatolithium (abbreviation: LiPP), 2-(2-pyridyl)-3-pyridinolatolithium (abbreviation: LiPPy), 4-phenyl-2-(2-pyridyl)phenolatolithium (abbreviation: LiPPP), lithium oxide (LiO ｘ ), alkali metals such as cesium carbonate, alkaline earth metals, or compounds thereof can be used.

[0329] Alternatively, the electron injection layer may be formed using a material having electron transport properties. For example, a compound having an unshared electron pair and an electron-deficient heteroaromatic ring may be used as the material having electron transport properties. Specifically, a compound having at least one of a pyridine ring, a diazine ring (pyrimidine ring, pyrazine ring, pyridazine ring), and a triazine ring may be used.

[0330] The organic compound having an unshared electron pair preferably has a lowest unoccupied molecular orbital (LUMO) of -3.6 eV to -2.3 eV. Generally, the highest occupied molecular orbital (HOMO) level and the LUMO level of an organic compound can be estimated by cyclic voltammetry (CV), photoelectron spectroscopy, optical absorption spectroscopy, inverse photoelectron spectroscopy, or the like.

[0331] For example, 4,7-diphenyl-1,10-phenanthroline (abbreviation: BPhen), 2,9-bis(naphthalen-2-yl)-4,7-diphenyl-1,10-phenanthroline (abbreviation: NBPhen), diquinoxalino[2,3-a:2',3'-c]phenazine (abbreviation: HATNA), 2,4,6-tris[3'-(pyridin-3-yl)biphenyl-3-yl]-1,3,5-triazine (abbreviation: TmPPPyTz), etc. can be used as the organic compound having an unshared electron pair. Note that NBPhen has a higher glass transition temperature (Tg) and is superior in heat resistance compared to BPhen.

[0332] The light-emitting layer is a layer containing a light-emitting substance. The light-emitting layer can contain one or more light-emitting substances. As the light-emitting substance, a substance that emits light of a color such as blue, purple, blue-purple, green, yellow-green, yellow, orange, or red is appropriately used. Furthermore, a substance that emits near-infrared light can also be used as the light-emitting substance.

[0333] Examples of the light-emitting material include fluorescent materials, phosphorescent materials, TADF materials, and quantum dot materials.

[0334] Examples of fluorescent materials include pyrene derivatives, anthracene derivatives, triphenylene derivatives, fluorene derivatives, carbazole derivatives, dibenzothiophene derivatives, dibenzofuran derivatives, dibenzoquinoxaline derivatives, quinoxaline derivatives, pyridine derivatives, pyrimidine derivatives, phenanthrene derivatives, and naphthalene derivatives.

[0335] Examples of phosphorescent materials include organometallic complexes (particularly iridium complexes) having a 4H-triazole skeleton, a 1H-triazole skeleton, an imidazole skeleton, a pyrimidine skeleton, a pyrazine skeleton, or a pyridine skeleton; organometallic complexes (particularly iridium complexes) having a phenylpyridine derivative having an electron-withdrawing group as a ligand; platinum complexes; and rare earth metal complexes.

[0336] The light-emitting layer may contain one or more organic compounds (host materials, assist materials, etc.) in addition to a light-emitting substance (guest material). As the one or more organic compounds, one or both of a hole-transporting material and an electron-transporting material can be used. Furthermore, as the one or more organic compounds, a bipolar material or a TADF material can be used.

[0337] The light-emitting layer preferably includes, for example, a phosphorescent material and a hole-transporting material and an electron-transporting material that are a combination that easily forms an exciplex. This configuration allows for efficient emission using Exciplex-Triple Energy Transfer (ExTET), which is energy transfer from the exciplex to the light-emitting material (phosphorescent material). By selecting a combination that forms an exciplex that emits light that overlaps with the wavelength of the lowest-energy absorption band of the light-emitting material, energy transfer becomes smooth, allowing for efficient emission. This configuration simultaneously enables high efficiency, low-voltage operation, and long life of the light-emitting device.

[0338] At least a part of the configuration examples exemplified in this embodiment and the corresponding drawings can be combined as appropriate with other configuration examples or drawings.

[0339] This embodiment mode can be implemented by appropriately combining at least a part thereof with other embodiment modes described in this specification.

[0340] Embodiment Mode 4 In this embodiment mode, a high-definition display device will be described.

[0341] [Example of Display Panel Configuration] Wearable electronic devices for VR, AR, and the like can provide 3D images by using parallax. In this case, it is necessary to display an image for the right eye within the field of view of the right eye and an image for the left eye within the field of view of the left eye. Here, the shape of the display unit of the display device may be a horizontally long rectangle, but pixels located outside the fields of view of the right and left eyes do not contribute to the display, and therefore always display black.

[0342] Therefore, it is preferable to divide the display section of the display panel into two regions, one for the right eye and one for the left eye, and not place pixels in the outer region that does not contribute to display. This reduces the power consumption required to write pixels. Also, since the load on source lines, gate lines, etc. is reduced, a high frame rate display becomes possible. This allows for smoother video display, enhancing the sense of realism.

[0343] Fig. 17A shows an example of the configuration of a display panel. In Fig. 17A, a display portion 702L for the left eye and a display portion 702R for the right eye are arranged inside a substrate 701. Note that in addition to the display portions 702L and 702R, a driver circuit, wiring, an IC, an FPC, and the like may also be arranged on the substrate 701.

[0344] The display units 702L and 702R shown in FIG. 17A have a square top surface shape.

[0345] The top surface shape of the display unit 702L and the display unit 702R may also be another regular polygon. FIG. 17B shows an example of a regular hexagon, FIG. 17C shows an example of a regular octagon, FIG. 17D shows an example of a regular decagon, and FIG. 17E shows an example of a regular dodecagon. In this way, by using a polygon with an even number of corners, the shape of the display unit can be made symmetrical. Note that polygons that are not regular polygons may also be used. Regular polygons or polygons with rounded corners may also be used.

[0346] Since the display unit is made up of pixels arranged in a matrix, the straight line portions of the outline of each display unit may not be straight lines in the strict sense, but may have stepped portions. In particular, straight line portions that are not parallel to the pixel arrangement direction will have a stepped top surface shape. However, since the user does not see the pixel shapes when viewing, even if the diagonal outline of the display unit is strictly stepped, it can be considered to be a straight line. Similarly, even if the curved portion of the outline of the display unit is strictly stepped, it can be considered to be a curve.

[0347] FIG. 17F shows an example in which the top surfaces of the display units 702L and 702R are circular.

[0348] The top surface shapes of the display units 702L and 702R may be asymmetrical, and may not be regular polygons.

[0349] Fig. 17G shows an example in which the top surface shapes of the display units 702L and 702R are asymmetrical octagons. Fig. 17H shows an example in which the top surface shapes of the display units 702L and 702R are asymmetrical. Even when the top surfaces of the display units 702L and 702R are asymmetrical, it is preferable to arrange the display units 702L and 702R symmetrically. This allows for the provision of natural-looking images.

[0350] Although the above description has been given of a configuration in which the display section is divided into two, it may be formed as a continuous shape.

[0351] Fig. 17I shows an example in which the two circular display units in Fig. 17F are connected together, and Fig. 17J shows an example in which the two regular octagonal display units in Fig. 17C are connected together.

[0352] This concludes the description of the exemplary configuration of the display panel.

[0353] At least a part of the configuration examples exemplified in this embodiment and the corresponding drawings can be combined as appropriate with other configuration examples or drawings.

[0354] This embodiment mode can be implemented by appropriately combining at least a part thereof with other embodiment modes described in this specification.

[0355] Embodiment 5 In this embodiment, a metal oxide (also referred to as an oxide semiconductor) that can be used for the OS transistor described in the above embodiment will be described.

[0356] The metal oxide used in the OS transistor preferably contains at least indium or zinc, and more preferably contains indium and zinc. For example, the metal oxide preferably contains indium, M (M is one or more selected from gallium, aluminum, yttrium, tin, silicon, boron, copper, vanadium, beryllium, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, magnesium, and cobalt), and zinc. In particular, M is preferably one or more selected from gallium, aluminum, yttrium, and tin, and more preferably gallium.

[0357] The metal oxide can be formed by a sputtering method, a chemical vapor deposition (CVD) method such as a metal organic chemical vapor deposition (MOCVD) method, or an atomic layer deposition (ALD) method.

[0358] Hereinafter, an oxide containing indium (In), gallium (Ga), and zinc (Zn) will be described as an example of a metal oxide. Note that an oxide containing indium (In), gallium (Ga), and zinc (Zn) may be referred to as an In—Ga—Zn oxide.

[0359] <Classification of Crystal Structure> Examples of the crystal structure of an oxide semiconductor include amorphous (including completely amorphous), c-axis-aligned crystalline line (CAAC), nanocrystalline line (nc), cloud-aligned composite (CAC), single crystal, and polycrystalline.

[0360] The crystalline structure of a film or substrate can be evaluated using an X-ray diffraction (XRD) spectrum. For example, it can be evaluated using an XRD spectrum obtained by GIXD (Grazing-Incident XRD) measurement. The GIXD method is also called the thin film method or the Seemann-Bohlin method. In the following, the XRD spectrum obtained by GIXD measurement may be simply referred to as the XRD spectrum.

[0361] For example, in the case of a quartz glass substrate, the peak shape of the XRD spectrum is almost symmetrical. On the other hand, in the case of an In-Ga-Zn oxide film having a crystalline structure, the peak shape of the XRD spectrum is asymmetrical. The asymmetrical peak shape of the XRD spectrum clearly indicates the presence of crystals in the film or substrate. In other words, if the peak shape of the XRD spectrum is not symmetrical, the film or substrate cannot be said to be in an amorphous state.

[0362] The crystalline structure of a film or substrate can be evaluated by a diffraction pattern (also called a nanobeam electron diffraction pattern) observed by nanobeam electron diffraction (NBED). For example, a halo is observed in the diffraction pattern of a quartz glass substrate, confirming that the quartz glass is in an amorphous state. Furthermore, a spot-like pattern is observed in the diffraction pattern of an In—Ga—Zn oxide film formed at room temperature, rather than a halo. Therefore, it is estimated that an In—Ga—Zn oxide film formed at room temperature is neither single-crystal nor polycrystalline, nor in an amorphous state, but is in an intermediate state, and it cannot be concluded that it is in an amorphous state.

[0363] <<Structure of Oxide Semiconductor>> Note that oxide semiconductors may be classified differently from the above when focusing on their structures. For example, oxide semiconductors are classified into single-crystal oxide semiconductors and other non-single-crystal oxide semiconductors. Examples of non-single-crystal oxide semiconductors include the above-mentioned CAAC-OS and nc-OS. Non-single-crystal oxide semiconductors include polycrystalline oxide semiconductors, pseudo-amorphous-like oxide semiconductors (a-like OSs), amorphous oxide semiconductors, and the like.

[0364] Here, the above-mentioned CAAC-OS, nc-OS, and a-like OS will be described in detail.

[0365] [CAAC-OS] A CAAC-OS is an oxide semiconductor having multiple crystalline regions, each with its c-axis aligned in a specific direction. The specific direction refers to the thickness direction of the CAAC-OS film, the normal direction to the surface where the CAAC-OS film is formed, or the normal direction to the surface of the CAAC-OS film. A crystalline region is a region having periodic atomic arrangement. If the atomic arrangement is considered as a lattice arrangement, a crystalline region is also a region with a uniform lattice arrangement. Furthermore, a CAAC-OS has a region where multiple crystalline regions are connected in the a-b plane direction, and the region may have distortion. Note that distortion refers to a portion where the lattice arrangement changes between a region with a uniform lattice arrangement and a region with another uniform lattice arrangement in a region where multiple crystalline regions are connected. In other words, a CAAC-OS is an oxide semiconductor whose c-axes are aligned and whose orientation is not clearly aligned in the a-b plane direction.

[0366] Each of the multiple crystalline regions is composed of one or more minute crystals (crystals with a maximum diameter of less than 10 nm). When a crystalline region is composed of a single minute crystal, the maximum diameter of the crystalline region is less than 10 nm. When a crystalline region is composed of many minute crystals, the size of the crystalline region may be several tens of nanometers.

[0367] In an In—Ga—Zn oxide, CAAC-OS tends to have a layered crystal structure (also referred to as a layered structure) in which a layer containing indium (In) and oxygen (hereinafter referred to as an In layer) and a layer containing gallium (Ga), zinc (Zn), and oxygen (hereinafter referred to as a (Ga, Zn) layer) are stacked. Note that indium and gallium are mutually substituted. Therefore, the (Ga, Zn) layer may contain indium. The In layer may contain gallium. The In layer may contain zinc. The layered structure is observed as a lattice image in a high-resolution transmission electron microscope (TEM) image, for example.

[0368] When a CAAC-OS film is subjected to structural analysis using an XRD apparatus, for example, a peak indicating c-axis orientation is detected at or near 2θ = 31° in out-of-plane XRD measurement using θ / 2θ scanning. Note that the position of the peak indicating c-axis orientation (the value of 2θ) may vary depending on the type and composition of the metal elements constituting the CAAC-OS.

[0369] For example, multiple bright spots are observed in the electron diffraction pattern of a CAAC-OS film, and the spots are observed at positions that are point-symmetric with respect to a spot of an incident electron beam that has passed through the sample (also referred to as a direct spot).

[0370] When a crystalline region is observed from the specific direction, the lattice arrangement in the crystalline region is basically a hexagonal lattice, but the unit cell is not necessarily a regular hexagon and may be a non-regular hexagon. The distortion may have a pentagonal, heptagonal, or other lattice arrangement. In CAAC-OS, no clear grain boundary can be identified even near the distortion. This indicates that the distortion in the lattice arrangement suppresses the formation of grain boundaries. This is thought to be because CAAC-OS can tolerate distortion due to the lack of close-packed oxygen atom arrangement in the a-b plane direction and the change in interatomic bond distance caused by metal atom substitution.

[0371] Note that a crystal structure in which clear grain boundaries are observed is called polycrystalline. The grain boundaries act as recombination centers, and are likely to trap carriers, resulting in a decrease in the on-state current of a transistor and a decrease in field-effect mobility. Therefore, CAAC-OS, in which clear grain boundaries are not observed, is one of the crystalline oxides having a crystal structure suitable for a semiconductor layer of a transistor. Note that a structure containing Zn is preferable for forming a CAAC-OS. For example, In—Zn oxide and In—Ga—Zn oxide are suitable because they can suppress the generation of grain boundaries more effectively than In oxide.

[0372] CAAC-OS is an oxide semiconductor with high crystallinity and no clear crystal grain boundaries. Therefore, it can be said that the CAAC-OS is less susceptible to a decrease in electron mobility due to crystal grain boundaries. Furthermore, since the crystallinity of an oxide semiconductor can be reduced by the inclusion of impurities, the formation of defects, or the like, the CAAC-OS can also be said to be an oxide semiconductor with few impurities and defects (such as oxygen vacancies). Therefore, an oxide semiconductor having a CAAC-OS has stable physical properties. Therefore, an oxide semiconductor having a CAAC-OS is heat-resistant and highly reliable. Furthermore, the CAAC-OS is stable even against high temperatures (so-called thermal budget) in the manufacturing process. Therefore, the use of a CAAC-OS in an OS transistor can increase the flexibility of the manufacturing process.

[0373] [nc-OS] The nc-OS has periodic atomic arrangement in a microscopic region (e.g., a region of 1 nm to 10 nm, particularly a region of 1 nm to 3 nm). In other words, the nc-OS has microcrystals. Note that the size of the microcrystals is, for example, 1 nm to 10 nm, particularly 1 nm to 3 nm, and therefore the microcrystals are also called nanocrystals. Furthermore, the nc-OS does not exhibit regularity in the crystal orientation between different nanocrystals. Therefore, no orientation is observed throughout the film. Therefore, depending on the analysis method, the nc-OS may be indistinguishable from an a-like OS or an amorphous oxide semiconductor. For example, when a structural analysis of an nc-OS film is performed using an XRD apparatus, no peak indicating crystallinity is detected in out-of-plane XRD measurement using θ / 2θ scanning. When an nc-OS film is subjected to electron diffraction (also referred to as selected-area electron diffraction) using an electron beam with a probe diameter larger than that of a nanocrystal (e.g., 50 nm or more), a diffraction pattern resembling a halo pattern is observed. On the other hand, when an nc-OS film is subjected to electron diffraction (also referred to as nanobeam electron diffraction) using an electron beam with a probe diameter close to or smaller than that of a nanocrystal (e.g., 1 nm to 30 nm), an electron diffraction pattern in which multiple spots are observed within a ring-shaped region centered on a direct spot may be obtained.

[0374] [a-Like OS] The a-like OS is an oxide semiconductor having a structure between the nc-OS and the amorphous oxide semiconductor. The a-like OS has a pore or low-density region. That is, the a-like OS has lower crystallinity than the nc-OS and the CAAC-OS. Furthermore, the a-like OS has a higher hydrogen concentration in the film than the nc-OS and the CAAC-OS.

[0375] <<Structure of Oxide Semiconductor>> Next, the above-described CAC-OS will be described in detail. Note that the CAC-OS relates to a material structure.

[0376] [CAC-OS] CAC-OS is, for example, a material in which elements constituting a metal oxide are unevenly distributed in a size of 0.5 nm to 10 nm, preferably 1 nm to 3 nm, or in the vicinity thereof. Note that hereinafter, a state in which one or more metal elements are unevenly distributed in a metal oxide and regions containing the metal elements are mixed in a size of 0.5 nm to 10 nm, preferably 1 nm to 3 nm, or in the vicinity thereof, is also referred to as a mosaic or patch state.

[0377] Furthermore, the CAC-OS has a mosaic structure in which a material is separated into a first region and a second region, and the first region is distributed throughout the film (hereinafter also referred to as a cloud structure). That is, the CAC-OS is a composite metal oxide having a structure in which the first region and the second region are mixed.

[0378] Here, the atomic ratios of In, Ga, and Zn to the metal elements constituting the CAC-OS in the In—Ga—Zn oxide are denoted as [In], [Ga], and [Zn], respectively. For example, in the CAC-OS in the In—Ga—Zn oxide, the first region is a region where [In] is larger than [In] in the composition of the CAC-OS film. The second region is a region where [Ga] is larger than [Ga] in the composition of the CAC-OS film. Alternatively, for example, the first region is a region where [In] is larger than [In] in the second region and [Ga] is smaller than [Ga] in the second region. The second region is a region where [Ga] is larger than [Ga] in the first region and [In] is smaller than [In] in the first region.

[0379] Specifically, the first region is a region whose main component is indium oxide, indium zinc oxide, or the like. The second region is a region whose main component is gallium oxide, gallium zinc oxide, or the like. In other words, the first region can be referred to as a region whose main component is In. The second region can be referred to as a region whose main component is Ga.

[0380] It should be noted that there are cases where a clear boundary between the first region and the second region cannot be observed.

[0381] Furthermore, CAC-OS in In—Ga—Zn oxide refers to a structure in which a mosaic of regions containing Ga as the main component and regions containing In as the main component are randomly arranged in a material composition containing In, Ga, Zn, and O. Therefore, it is presumed that CAC-OS has a structure in which metal elements are distributed nonuniformly.

[0382] The CAC-OS can be formed by sputtering, for example, without intentionally heating the substrate. When forming the CAC-OS by sputtering, any one or more of an inert gas (typically argon), oxygen gas, and nitrogen gas may be used as the deposition gas. The lower the flow rate of oxygen gas relative to the total flow rate of deposition gas during deposition, the more preferable it is. For example, the flow rate of oxygen gas relative to the total flow rate of deposition gas during deposition is set to 0% or more and less than 30%, preferably 0% or more and 10% or less.

[0383] Furthermore, for example, in the case of CAC-OS in an In—Ga—Zn oxide, EDX mapping obtained using energy dispersive X-ray spectroscopy (EDX) can confirm that the CAC-OS has a structure in which a region containing In as a main component (first region) and a region containing Ga as a main component (second region) are unevenly distributed and mixed.

[0384] Here, the first region has higher conductivity than the second region. That is, the flow of carriers through the first region causes the metal oxide to exhibit conductivity. Therefore, the first region is distributed in a cloud-like manner in the metal oxide, thereby achieving a high field-effect mobility (μ).

[0385] On the other hand, the second region has higher insulating properties than the first region. That is, the second region is distributed in the metal oxide, thereby suppressing leakage current.

[0386] Therefore, when a CAC-OS is used in a transistor, the conductivity due to the first region and the insulating property due to the second region act complementarily, thereby providing the CAC-OS with a switching function (a function of turning on / off). In other words, a CAC-OS has a conductive function in a part of the material and an insulating function in a part of the material, and the entire material functions as a semiconductor. By separating the conductive function and the insulating function, both functions can be maximized. Therefore, by using a CAC-OS in a transistor, a high on-current (I ｏｎ), high field-effect mobility (μ), and good switching behavior can be achieved.

[0387] Furthermore, a transistor using the CAC-OS has high reliability, and therefore, the CAC-OS is ideal for various semiconductor devices such as display devices.

[0388] Oxide semiconductors have a variety of structures, each of which has different characteristics. The oxide semiconductor of one embodiment of the present invention may include two or more of an amorphous oxide semiconductor, a polycrystalline oxide semiconductor, an a-like OS, a CAC-OS, an nc-OS, and a CAAC-OS.

[0389] <Transistor Having Oxide Semiconductor> Next, a case where the oxide semiconductor is used for a transistor will be described.

[0390] By using the oxide semiconductor for a transistor, a transistor with high field-effect mobility and high reliability can be realized.

[0391] For the transistor, an oxide semiconductor having a low carrier concentration is preferably used. For example, the carrier concentration of the oxide semiconductor is 1×10 １７ cm −３ Below 1 × 10, preferably １５ cm −３ More preferably, 1×10 １３ cm −３ Less than 1×10, more preferably 1×10 １１ cm −３ More preferably, 1×10 １０ cm −３ is less than 1×10 −９ cm −３ That is all. Note that in order to reduce the carrier concentration of an oxide semiconductor film, the impurity concentration in the oxide semiconductor film may be reduced to reduce the density of defect states. In this specification and the like, a semiconductor having a low impurity concentration and a low density of defect states is referred to as a highly purified intrinsic or substantially highly purified intrinsic oxide semiconductor. Note that an oxide semiconductor having a low carrier concentration may also be referred to as a highly purified intrinsic or substantially highly purified intrinsic oxide semiconductor.

[0392] Furthermore, a highly purified intrinsic or substantially highly purified intrinsic oxide semiconductor film has a low density of defect states, and therefore the density of trap states may also be low.

[0393] Furthermore, charges trapped in the trap states of an oxide semiconductor take a long time to dissipate and may behave like fixed charges. Therefore, a transistor in which a channel formation region is formed in an oxide semiconductor with a high density of trap states may have unstable electrical characteristics.

[0394] Therefore, reducing the impurity concentration in the oxide semiconductor is effective for stabilizing the electrical characteristics of a transistor. Furthermore, in order to reduce the impurity concentration in the oxide semiconductor, it is preferable to also reduce the impurity concentration in adjacent films. Examples of impurities include hydrogen, nitrogen, alkali metals, alkaline earth metals, iron, nickel, and silicon. Note that impurities in an oxide semiconductor refer to, for example, elements other than the main components constituting the oxide semiconductor. For example, an element with a concentration of less than 0.1 atomic % can be considered an impurity.

[0395] <Impurities> Here, the influence of each impurity in an oxide semiconductor will be described.

[0396] When an oxide semiconductor contains silicon or carbon, which is one of Group 14 elements, defect levels are formed in the oxide semiconductor. Therefore, the concentration of silicon or carbon in the oxide semiconductor and the concentration of silicon or carbon near the interface with the oxide semiconductor (concentration obtained by secondary ion mass spectrometry (SIMS)) are set to 2×10 １８ atoms / cm ３ Below 2 × 10, preferably １７ atoms / cm ３ The following applies.

[0397] Furthermore, when an oxide semiconductor contains an alkali metal or an alkaline earth metal, defect levels are formed and carriers are generated in some cases. Therefore, a transistor using an oxide semiconductor containing an alkali metal or an alkaline earth metal is likely to have normally-on characteristics. For this reason, when the concentration of the alkali metal or the alkaline earth metal in the oxide semiconductor obtained by SIMS is 1×10 １８ atoms / cm ３ Below 2 × 10, preferably １６ atoms / cm ３ Do the following:

[0398] Furthermore, when nitrogen is contained in an oxide semiconductor, electrons serving as carriers are generated, the carrier concentration increases, and the semiconductor is likely to become n-type. As a result, a transistor using an oxide semiconductor containing nitrogen as a semiconductor tends to have normally-on characteristics. Alternatively, when nitrogen is contained in an oxide semiconductor, trap states may be formed. As a result, the electrical characteristics of the transistor may become unstable. For this reason, the nitrogen concentration in the oxide semiconductor obtained by SIMS is set to 5×10 １９ atoms / cm ３ Less than 5×10 １８ atoms / cm ３ Less than 1×10, more preferably 1×10 １８ atoms / cm ３ or less, more preferably 5 × 10 １７ atoms / cm ３ Do the following:

[0399] Furthermore, hydrogen contained in an oxide semiconductor may react with oxygen bonded to a metal atom to form water, which may form an oxygen vacancy. Hydrogen entering the oxygen vacancy may generate electrons as carriers. Furthermore, some of the hydrogen may bond with oxygen bonded to a metal atom to generate electrons as carriers. Therefore, a transistor using an oxide semiconductor containing hydrogen is likely to have normally-on characteristics. Therefore, it is preferable to reduce the amount of hydrogen in the oxide semiconductor as much as possible. Specifically, the hydrogen concentration in the oxide semiconductor obtained by SIMS is measured to be 1×10 ２０ atoms / cm ３less than 1×10 １９ atoms / cm ３ less than 5×10 １８ atoms / cm ３ less than 1×10 １８ atoms / cm ３ Make it less than.

[0400] When an oxide semiconductor with sufficiently reduced impurities is used for a channel formation region of a transistor, stable electrical characteristics can be obtained.

[0401] This embodiment mode can be implemented by appropriately combining at least a part thereof with other embodiment modes described in this specification.

[0402] Embodiment 6 In this embodiment, electronic devices of one embodiment of the present invention will be described with reference to FIGS.

[0403] The electronic devices of this embodiment include the display device of one embodiment of the present invention. The display device of one embodiment of the present invention can easily achieve high definition, high resolution, and a large size. Therefore, the display device of one embodiment of the present invention can be used as a display portion of various electronic devices.

[0404] Furthermore, the display device of one embodiment of the present invention can be manufactured at low cost, which leads to a reduction in the manufacturing cost of electronic devices.

[0405] Examples of electronic devices include electronic devices with relatively large screens such as television sets, desktop or notebook personal computers, computer monitors, digital signage, large game machines such as pachinko machines, as well as digital cameras, digital video cameras, digital photo frames, mobile phones, portable game machines, personal digital assistants, and sound playback devices.

[0406] In particular, the display device of one embodiment of the present invention can be suitably used in electronic devices having a relatively small display portion because it can increase the resolution. Examples of such electronic devices include information terminals (wearable devices) such as wristwatches and bracelets, as well as head-mounted wearable devices such as VR devices and eyeglass-type AR devices. Examples of wearable devices include devices for Substitutional Reality (SR) and Mixed Reality (MR).

[0407] The display device of one embodiment of the present invention preferably has an extremely high resolution such as HD (1280 × 720 pixels), FHD (1920 × 1080 pixels), WQHD (2560 × 1440 pixels), WQXGA (2560 × 1600 pixels), 4K2K (3840 × 2160 pixels), or 8K4K (7680 × 4320 pixels). A resolution of 4K2K, 8K4K, or higher is particularly preferable. Furthermore, the pixel density (resolution) of the display device of one embodiment of the present invention is preferably 300 ppi or higher, more preferably 500 ppi or higher, more preferably 1000 ppi or higher, more preferably 2000 ppi or higher, more preferably 3000 ppi or higher, more preferably 5000 ppi or higher, and even more preferably 7000 ppi or higher. By using a display device with such high resolution or high definition, it is possible to further enhance the sense of presence and depth in electronic devices for personal use such as portable or home use.

[0408] The electronic device of this embodiment can be incorporated along the curved surface of the inner or outer wall of a house or building, or the interior or exterior of an automobile.

[0409] The electronic device of this embodiment may have an antenna. By receiving a signal through the antenna, images, information, and the like can be displayed on a display portion. In addition, when the electronic device has an antenna and a secondary battery, the antenna may be used for contactless power transmission.

[0410] The electronic device of this embodiment may have a sensor (including the function of detecting, detecting, or measuring force, displacement, position, velocity, acceleration, angular velocity, rotation speed, distance, light, liquid, magnetism, temperature, chemical substance, sound, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, gradient, vibration, odor, or infrared rays).

[0411] The electronic device of the present embodiment can have various functions, such as a function to display various information (still images, videos, text images, etc.) on a display unit, a touch panel function, a function to display a calendar, date, time, etc., a function to execute various software (programs), a wireless communication function, a function to read out programs or data recorded on a recording medium, etc.

[0412] The electronic device 6500 shown in FIG. 18A is a portable information terminal that can be used as a smartphone.

[0413] The electronic device 6500 includes a housing 6501, a display portion 6502, a power button 6503, a button 6504, a speaker 6505, a microphone 6506, a camera 6507, a light source 6508, and the like. The display portion 6502 has a touch panel function.

[0414] The display device of one embodiment of the present invention can be applied to the display portion 6502 .

[0415] FIG. 18B is a schematic cross-sectional view including the end of the housing 6501 on the microphone 6506 side.

[0416] A light-transmitting protective member 6510 is provided on the display surface side of the housing 6501, and a display panel 6511, optical members 6512, a touch sensor panel 6513, a printed circuit board 6517, a battery 6518, etc. are arranged in the space surrounded by the housing 6501 and the protective member 6510.

[0417] A display panel 6511, an optical member 6512, and a touch sensor panel 6513 are fixed to the protective member 6510 by adhesive layers (not shown).

[0418] In a region outside the display portion 6502, a part of the display panel 6511 is folded back, and an FPC 6515 is connected to the folded back part. An IC 6516 is mounted on the FPC 6515. The FPC 6515 is connected to a terminal provided on a printed circuit board 6517.

[0419] The flexible display (flexible display device) of one embodiment of the present invention can be applied to the display panel 6511. Therefore, an extremely lightweight electronic device can be realized. In addition, since the display panel 6511 is extremely thin, a large-capacity battery 6518 can be mounted thereon while keeping the thickness of the electronic device small. Furthermore, by folding back a part of the display panel 6511 and arranging a connection portion with the FPC 6515 on the back side of the pixel portion, an electronic device with a narrow frame can be realized.

[0420] 19A shows an example of a television set. A television set 7100 has a display portion 7000 built into a housing 7101. Here, the housing 7101 is supported by a stand 7103.

[0421] The display device of one embodiment of the present invention can be applied to the display portion 7000 .

[0422] 19A can be operated using operation switches provided on the housing 7101 and a separate remote control 7111. Alternatively, the display portion 7000 may be provided with a touch sensor, and the television set 7100 may be operated by touching the display portion 7000 with a finger or the like. The remote control 7111 may have a display portion that displays information output from the remote control 7111. Using operation keys or a touch panel provided on the remote control 7111, the channel and volume can be controlled, and an image displayed on the display portion 7000 can be controlled.

[0423] The television device 7100 is configured to include a receiver, a modem, and the like. The receiver can receive general television broadcasts. Furthermore, by connecting to a wired or wireless communication network via the modem, it is possible to perform one-way (from a sender to a receiver) or two-way (between a sender and a receiver, or between receivers, etc.) information communication.

[0424] 19B shows an example of a laptop personal computer 7200. The laptop personal computer 7200 includes a housing 7211, a keyboard 7212, a pointing device 7213, an external connection port 7214, and the like. The housing 7211 includes a display portion 7000.

[0425] The display device of one embodiment of the present invention can be applied to the display portion 7000 .

[0426] 19C and 19D show an example of digital signage.

[0427] 19C includes a housing 7301, a display portion 7000, and a speaker 7303. The digital signage 7300 may further include an LED lamp, operation keys (including a power switch or an operation switch), a connection terminal, various sensors, a microphone, and the like.

[0428] 19D shows a digital signage 7400 attached to a cylindrical pillar 7401. The digital signage 7400 has a display unit 7000 provided along the curved surface of the pillar 7401.

[0429] 19C and 19D, the display device of one embodiment of the present invention can be applied to the display portion 7000.

[0430] The larger the display unit 7000, the more information can be provided at one time. Also, the larger the display unit 7000, the more easily it attracts people's attention, which can increase the advertising effectiveness of, for example, advertisements.

[0431] Applying a touch panel to the display unit 7000 is preferable because it not only displays images or videos on the display unit 7000 but also allows the user to intuitively operate it. Furthermore, when used to provide information such as route information or traffic information, the intuitive operation can improve usability.

[0432] 19C and 19D , the digital signage 7300 or the digital signage 7400 is preferably capable of wirelessly linking with an information terminal 7311 or an information terminal 7411 such as a smartphone carried by a user. For example, advertising information displayed on the display unit 7000 can be displayed on the screen of the information terminal 7311 or the information terminal 7411. By operating the information terminal 7311 or the information terminal 7411, the display on the display unit 7000 can be switched.

[0433] Furthermore, the digital signage 7300 or the digital signage 7400 can be made to run a game using the screen of the information terminal 7311 or the information terminal 7411 as an operation means (controller), thereby allowing an unspecified number of users to simultaneously participate in and enjoy the game.

[0434] FIG. 20A is a diagram showing the appearance of the camera 8000 with the viewfinder 8100 attached.

[0435] The camera 8000 includes a housing 8001, a display unit 8002, operation buttons 8003, a shutter button 8004, and the like. A detachable lens 8006 is attached to the camera 8000. Note that the lens 8006 and the housing 8001 of the camera 8000 may be integrated together.

[0436] The camera 8000 can capture an image by pressing a shutter button 8004 or touching a display portion 8002 that functions as a touch panel.

[0437] The housing 8001 has a mount with electrodes, and can be connected to a finder 8100 as well as a strobe device and the like.

[0438] The finder 8100 includes a housing 8101, a display portion 8102, a button 8103, and the like.

[0439] The housing 8101 is attached to the camera 8000 by a mount that engages with the mount of the camera 8000. The viewfinder 8100 can display an image received from the camera 8000 on a display portion 8102.

[0440] The button 8103 has a function as a power button or the like.

[0441] The display device of one embodiment of the present invention can be applied to a display portion 8002 of a camera 8000 and a display portion 8102 of a finder 8100. Note that the camera 8000 may have a built-in finder.

[0442] FIG. 20B is a diagram showing the appearance of the head-mounted display 8200.

[0443] The head-mounted display 8200 includes a mounting portion 8201, a lens 8202, a main body 8203, a display portion 8204, and a cable 8205. The mounting portion 8201 has a built-in battery 8206.

[0444] A cable 8205 supplies power from a battery 8206 to the main body 8203. The main body 8203 includes a wireless receiver or the like and can display received video information on a display portion 8204. The main body 8203 also includes a camera and can use information on the movement of the user's eyeballs or eyelids as an input means.

[0445] The wearing unit 8201 may have a plurality of electrodes at positions that come into contact with the user, capable of detecting a current that flows in accordance with the movement of the user's eyeballs, and may have a function of recognizing the line of sight. The wearing unit 8201 may also have a function of monitoring the user's pulse based on the current that flows through the electrodes. The wearing unit 8201 may also have various sensors such as a temperature sensor, a pressure sensor, and an acceleration sensor, and may have a function of displaying biometric information of the user on the display unit 8204 and a function of changing an image displayed on the display unit 8204 in accordance with the movement of the user's head.

[0446] The display device of one embodiment of the present invention can be applied to the display portion 8204 .

[0447] 20C to 20E are diagrams showing the appearance of a head mounted display 8300. The head mounted display 8300 includes a housing 8301, a display portion 8302, a band-shaped fixture 8304, and a pair of lenses 8305.

[0448] A user can view the display on the display portion 8302 through the lens 8305. Note that it is preferable to curve the display portion 8302 because the user can feel a high sense of presence. In addition, by viewing different images displayed in different regions of the display portion 8302 through the lens 8305, three-dimensional display using parallax can be performed. Note that the present invention is not limited to a configuration in which one display portion 8302 is provided, and two display portions 8302 may be provided, with one display portion provided for each eye of the user.

[0449] The display device of one embodiment of the present invention can be applied to the display portion 8302. The display device of one embodiment of the present invention can also achieve extremely high definition. For example, even when the display is enlarged and viewed using the lens 8305 as shown in FIG. 20E, the pixels are hardly visible to the user. That is, the display portion 8302 can be used to allow the user to view a highly realistic image.

[0450] 20F is a diagram showing the appearance of a goggle-type head-mounted display 8400. The head-mounted display 8400 includes a pair of housings 8401, an attachment portion 8402, and a buffer member 8403. A display portion 8404 and a lens 8405 are provided in each of the pair of housings 8401. By displaying different images on the pair of display portions 8404, three-dimensional display using parallax can be performed.

[0451] A user can view the display portion 8404 through the lens 8405. The lens 8405 has a focus adjustment mechanism, and the position of the lens 8405 can be adjusted according to the user's eyesight using the focus adjustment mechanism. The display portion 8404 is preferably a square or a horizontally long rectangle. This can enhance the sense of realism.

[0452] The wearing portion 8402 is preferably adjustable to fit the size of the user's face and has plasticity and elasticity to prevent it from slipping off. Furthermore, a portion of the wearing portion 8402 preferably has a vibration mechanism that functions as a bone conduction earphone. This allows the user to enjoy video and audio simply by wearing the device, without the need for separate audio equipment such as earphones or speakers. The housing 8401 may also have a function for outputting audio data via wireless communication.

[0453] The mounting portion 8402 and the buffer member 8403 are portions that come into contact with the user's face (forehead, cheeks, etc.). The close contact of the buffer member 8403 with the user's face can prevent light leakage and enhance the sense of immersion. The buffer member 8403 is preferably made of a soft material so that it can be in close contact with the user's face when the user wears the head-mounted display 8400. For example, materials such as rubber, silicone rubber, urethane, and sponge can be used. Furthermore, using a sponge or the like with its surface covered with cloth, leather (natural leather or synthetic leather), or the like can prevent gaps from forming between the user's face and the buffer member 8403, thereby effectively preventing light leakage. Furthermore, using such a material is preferable because it feels pleasant to the touch and prevents the user from feeling cold when worn in cold seasons. It is preferable that the buffer member 8403 or the mounting portion 8402, or other components that come into contact with the user's skin, are removable for easy cleaning or replacement.

[0454] The electronic device shown in Figures 21A to 21F has a housing 9000, a display unit 9001, a speaker 9003, operation keys 9005 (including a power switch or an operation switch), a connection terminal 9006, a sensor 9007 (including the function of detecting, detecting, or measuring force, displacement, position, speed, acceleration, angular velocity, rotation speed, distance, light, liquid, magnetism, temperature, chemical substance, sound, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, gradient, vibration, odor, or infrared rays), a microphone 9008, etc.

[0455] The electronic devices shown in Figures 21A to 21F have various functions. For example, they may have a function to display various information (still images, videos, text images, etc.) on a display unit, a touch panel function, a function to display a calendar, date, or time, a function to control processing using various software (programs), a wireless communication function, a function to read and process programs or data recorded on a recording medium, etc. Note that the functions of the electronic devices are not limited to these, and they may have various other functions. The electronic devices may have multiple display units. Furthermore, the electronic devices may have a function to include a camera or the like to capture still images or videos and store them on a recording medium (external or built-in to the camera), a function to display the captured images on a display unit, etc.

[0456] The display device of one embodiment of the present invention can be applied to the display portion 9001 .

[0457] The electronic device shown in FIGS. 21A to 21F will be described in detail below.

[0458] FIG. 21A is a perspective view showing a mobile information terminal 9101. The mobile information terminal 9101 can be used as, for example, a smartphone. Note that the mobile information terminal 9101 may be provided with a speaker 9003, a connection terminal 9006, a sensor 9007, and the like. The mobile information terminal 9101 can display text and image information on multiple surfaces. FIG. 21A shows an example in which three icons 9050 are displayed. Information 9051, indicated by a dashed rectangle, can also be displayed on another surface of the display unit 9001. Examples of the information 9051 include notifications of incoming emails, SNS messages, phone calls, etc., the title of the email or SNS message, the sender's name, the date and time, the remaining battery level, and the strength of antenna reception. Alternatively, an icon 9050 or the like may be displayed in the position where the information 9051 is displayed.

[0459] 21B is a perspective view showing the mobile information terminal 9102. The mobile information terminal 9102 has a function of displaying information on three or more surfaces of the display unit 9001. Here, an example is shown in which information 9052, information 9053, and information 9054 are displayed on different surfaces. For example, a user can check information 9053 displayed in a position that can be observed from above the mobile information terminal 9102 while the mobile information terminal 9102 is placed in a breast pocket of clothes. The user can check the display without taking the mobile information terminal 9102 out of the pocket and decide, for example, whether to answer a call.

[0460] FIG. 21C is a perspective view showing a wristwatch-type mobile information terminal 9200. The mobile information terminal 9200 can be used as, for example, a smart watch (registered trademark). The display surface of the display unit 9001 is curved, and display can be performed along the curved display surface. The mobile information terminal 9200 can also perform hands-free communication by intercommunicating with, for example, a headset capable of wireless communication. The mobile information terminal 9200 can also perform data transmission and charging with another information terminal through a connection terminal 9006. Charging may be performed by wireless power supply.

[0461] 21D to 21F are perspective views showing a foldable mobile information terminal 9201. Also, FIG. 21D is a perspective view of the mobile information terminal 9201 in an unfolded state, FIG. 21F is a perspective view of the mobile information terminal 9201 in a folded state, and FIG. 21E is a perspective view of a state in the process of changing from one of FIG. 21D and FIG. 21F to the other. The mobile information terminal 9201 has excellent portability in a folded state, and excellent display visibility due to a seamless, wide display area in an unfolded state. The display portion 9001 of the mobile information terminal 9201 is supported by three housings 9000 connected by hinges 9055. For example, the display portion 9001 can be bent with a curvature radius of 0.1 mm or more and 150 mm or less.

[0462] At least a part of the configuration examples exemplified in this embodiment and the corresponding drawings can be combined as appropriate with other configuration examples or drawings.

[0463] This embodiment mode can be implemented by appropriately combining at least a part thereof with other embodiment modes described in this specification.

[0464] In this example, an insulating layer was formed to cover the edge of the pixel electrode, and step coverage was confirmed when an EL layer was further formed.

[0465] First, a substrate was prepared on a glass substrate on which a pixel circuit including transistors, wiring, etc. and a planarization film covering the pixel circuit were formed. Next, conductive layers 111a and 111b were laminated on the planarization film to form a pixel electrode. Next, insulating layers 132a and 132b were laminated as insulating layers 131 covering the edges of the pixel electrode and insulating layers 132a and 132b covering the insulating layer 131. Next, an EL film 112Rf, a sacrificial film 144, and a sacrificial film 146 were formed.

[0466] The conductive layer 111a was formed by sputtering an alloy of silver (Ag), palladium (Pd), and copper (Cu) (Ag-Pd-Cu (APC)) to a thickness of 100 nm, and the conductive layer 111b was formed by sputtering an indium tin oxide containing silicon oxide (ITSO) to a thickness of 100 nm.

[0467] The insulating layer 131 was formed from photosensitive polyimide to a thickness of about 1 μm.

[0468] The insulating layer 132a was a silicon nitride film formed by plasma CVD to a thickness of about 50 nm, and the insulating layer 132b was a silicon oxynitride film formed by plasma CVD to a thickness of about 150 nm.

[0469] The EL film 112Rf was formed by vapor deposition of a hole injection layer, a hole transport layer, a light-emitting layer, and an electron transport layer to a thickness of approximately 200 nm. The sacrificial film 144 was formed by ALD of a metal oxide film to a thickness of approximately 30 nm. The sacrificial film 146 was formed by sputtering of a metal oxide film different from the sacrificial film 144 to a thickness of approximately 50 nm.

[0470] A cross-section of the substrate on which the sacrificial film 146 had been formed was observed. Fig. 22A is a cross-sectional STEM image of the end portions of the insulating layers 131, 132a, and 132b and their vicinity. Fig. 22B is a schematic diagram showing the outlines of the layers in Fig. 21A.

[0471] 22A, it was confirmed that the taper angle of the end of insulating layer 132a was different from the taper angle of the end of insulating layer 132b. The taper angle of insulating layer 132a was approximately 90 degrees, and the taper angle of insulating layer 132b was approximately 65 degrees.

[0472] It was also confirmed that the EL film 112Rf well covered the surfaces of the insulating layers 132a and 132b. Furthermore, the sacrificial films 144 and 146 on the EL film 112Rf also well covered the EL film 112Rf, and no defects were observed.

[0473] The above is a description of the embodiment.

[0474] DESCRIPTION OF SYMBOLS 100, 100A-F: Display device 101: Substrate 110: Light-emitting element 110R, G, B, P, Q: Light-emitting element 111: Pixel electrode 111a, b: Conductive layer 111R, G, B, P, Q: Pixel electrode 111C: Connection electrode 112: EL layer 112R, G, B, P, Q: EL layer 112Rf, Gf, Bf: EL film 113: Common electrode 114: EL layer 115R, G, B: Optical adjustment layer 121: Protective layer 130: Connection portion 131, 132a, b: Insulating layer 131f, 132f: Insulating film 133: Space 141, 143a-c: Resist mask 141f: Resist film 144, 144a-c: Sacrificial film 145, 145a-c: Sacrificial layer 146, 146a-c: Sacrificial film 147, 147a-c: Sacrificial layer 151: Photomask 152, 153: Photo

Claims

1. a first pixel electrode, a second pixel electrode, a first insulating layer, a second insulating layer, a first EL layer, a second EL layer, and a common electrode; the first pixel electrode and the second pixel electrode are provided side by side, the first insulating layer covers an end portion of the first pixel electrode and an end portion of the second pixel electrode; a portion of an end of the first insulating layer overlaps with an upper surface of the first pixel electrode, and another portion of the end of the first insulating layer overlaps with an upper surface of the second pixel electrode; the second insulating layer is provided on the first pixel electrode, the second pixel electrode, and the first insulating layer, and covers an end portion of the first insulating layer; a portion of an end of the second insulating layer overlaps with an upper surface of the first pixel electrode, and another portion of the end of the second insulating layer overlaps with an upper surface of the second pixel electrode; the first EL layer is provided on the first pixel electrode, the second EL layer is provided on the second pixel electrode, an end portion of the first EL layer and an end portion of the second EL layer face each other and overlap the first insulating layer; the common electrode has a portion overlapping the first EL layer and a portion overlapping the second EL layer, the first insulating layer includes an organic resin; the second insulating layer includes an inorganic insulating material; the second insulating layer includes a first insulating film and a second insulating film on the first insulating film; a first angle formed between a side surface and a bottom surface of the first insulating film and a second angle formed between a side surface and a bottom surface of the second insulating film are different from each other.

2. In claim 1, the first insulating film is thinner than the second insulating film; The display device, wherein the first angle is greater than the second angle.

3. In claim 1, the second insulating film is thinner than the first insulating film; The second angle is greater than the first angle.

4. In any one of claims 1 to 3, 13. A display device, wherein the first insulating film contains silicon oxide, silicon oxynitride, silicon nitride oxide, silicon nitride, aluminum oxide, aluminum oxynitride, hafnium oxide, indium gallium oxide, or indium gallium zinc oxide.

5. In any one of claims 1 to 4, The display device, wherein the second insulating film contains silicon oxide, silicon oxynitride, silicon nitride oxide, silicon nitride, aluminum oxide, aluminum oxynitride, hafnium oxide, indium gallium oxide, or indium gallium zinc oxide.

6. In any one of claims 1 to 5, the first insulating film includes silicon nitride; The display device, wherein the second insulating film contains silicon oxide or silicon oxynitride.

7. In any one of claims 1 to 6, The display device, wherein the first insulating layer contains an acrylic resin, a polyimide resin, an epoxy resin, a polyamide resin, a polyimideamide resin, a siloxane resin, a benzocyclobutene-based resin, a phenolic resin, or a precursor of these resins.

8. In any one of claims 1 to 7, The second insulating layer has a recess in a region that does not overlap with either the first EL layer or the second EL layer.

9. In any one of claims 1 to 7, The second insulating layer is divided in a region where the second insulating layer does not overlap with either the first EL layer or the second EL layer.