Method for manufacturing a display device

Abstract

To provide a display device with high display quality and reliability. [Solution] A display device comprising a first light-emitting element, a second light-emitting element disposed adjacent to the first light-emitting element, a first protective layer, a second protective layer, and an insulating layer. The first light-emitting element comprises a first pixel electrode, a first EL layer, and a common electrode, and the second light-emitting element comprises a second pixel electrode, a second EL layer, and a common electrode. The first EL layer is provided on the first pixel electrode, and the second EL layer is provided on the second pixel electrode. The first protective layer has regions that overlap with the side surfaces of the first pixel electrode, the side surfaces of the second pixel electrode, the side surfaces of the first EL layer, and the side surfaces of the second EL layer. The insulating layer is provided on the first protective layer, and the second protective layer is provided on the insulating layer. The common electrode is provided on the first EL layer, the second EL layer, and the second protective layer.

Description

[Technical Field]

[0001] One aspect of the present invention relates to a display device and a method for manufacturing the same. Another aspect of the present invention relates to a display module and an electronic device.

[0002] It should be noted that one aspect of the present invention is not limited to the above-mentioned technical field. Examples of technical fields of one aspect of the present invention disclosed herein include semiconductor devices, display devices, light-emitting devices, energy storage devices, memory devices, electronic devices, lighting devices, input devices, input / output devices, methods for driving them, or methods for manufacturing them. A semiconductor device refers to any device that can function by utilizing semiconductor properties. [Background technology]

[0003] In recent years, there has been a growing demand for higher resolution display panels. Devices requiring high-resolution display panels include, for example, smartphones, tablet devices, and notebook computers. Furthermore, stationary display devices such as television sets and monitors are also required to have higher resolutions. Moreover, devices that require the highest resolution include, for example, devices for virtual reality (VR) and augmented reality (AR).

[0004] Furthermore, typical examples of display devices applicable to display panels include liquid crystal displays, light-emitting devices equipped with light-emitting elements such as organic EL (Electro Luminescence) elements or light-emitting diodes (LEDs), and electronic paper that displays information using, for example, electrophoretic methods.

[0005] For example, the basic structure of an organic EL device is one in which a layer containing a light-emitting organic compound is sandwiched between a pair of electrodes. By applying a voltage to this device, light emission can be obtained from the light-emitting organic compound. A display device to which such an organic EL device is applied can realize a thin, lightweight, high-contrast, and low-power consumption display device because it does not require a backlight, which was necessary in, for example, a liquid crystal display device. For example, an example of a display device using an organic EL device is described in Patent Document 1.

[0006] Patent Document 2 discloses a display device for VR using an organic EL device.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0008] One aspect of the present invention aims to provide a display device with high display quality. One aspect of the present invention aims to provide a highly reliable display device. One aspect of the present invention aims to provide a display device with low power consumption. One aspect of the present invention aims to provide a display device that can be easily made high-definition. One aspect of the present invention aims to provide a low-cost display device. One aspect of the present invention aims to provide a display device that combines high display quality and high definition. One aspect of the present invention aims to provide a display device with high contrast. One aspect of the present invention aims to provide a display device having a novel configuration.

[0009] One aspect of the present invention aims to provide a method for manufacturing a display device with high display quality. One aspect of the present invention aims to provide a method for manufacturing a display device with high reliability. One aspect of the present invention aims to provide a method for manufacturing a display device with low power consumption. One aspect of the present invention aims to provide a method for manufacturing a display device that can be easily made with high definition. One aspect of the present invention aims to provide a method for manufacturing a display device with low cost. One aspect of the present invention aims to provide a method for manufacturing a display device that combines high display quality and high definition. One aspect of the present invention aims to provide a method for manufacturing a display device with high contrast. One aspect of the present invention aims to provide a method for manufacturing a display device having a novel configuration.

[0010] Note that the description of these problems does not prevent the existence of other problems. Note that one aspect of the present invention does not need to solve all of these problems. Note that other problems can be extracted from the descriptions in the specification, drawings, claims, etc.

Means for Solving the Problems

[0011] One aspect of the present invention includes a first light-emitting element, a second light-emitting element arranged adjacent to the first light-emitting element, a first protective layer, a second protective layer, and an insulating layer. The first light-emitting element has a first pixel electrode, a first EL layer, and a common electrode. The second light-emitting element has a second pixel electrode, a second EL layer, and a common electrode. The first EL layer is provided on the first pixel electrode, the second EL layer is provided on the second pixel electrode, the first protective layer has a region overlapping the side surfaces of the first pixel electrode, the side surfaces of the second pixel electrode, the side surfaces of the first EL layer, and the side surfaces of the second EL layer. The insulating layer is provided on the first protective layer, the second protective layer is provided on the insulating layer, and the common electrode is provided on the first EL layer, the second EL layer, and the second protective layer.

[0012] Alternatively, in the above aspect, the insulating layer may be provided between the first EL layer and the second EL layer.

[0013] Alternatively, in the above embodiment, the display device may have a third protective layer, the third protective layer having areas in contact with the side and bottom surfaces of the first protective layer.

[0014] Alternatively, in the above embodiment, the first to third protective layers may have an inorganic material.

[0015] Alternatively, in the above embodiment, the first protective layer has regions in contact with the side and bottom surfaces of the insulating layer, the second protective layer has regions in contact with the top surface of the insulating layer, and the first and second protective layers may have nitrides.

[0016] Alternatively, in the above embodiment, the first protective layer and the second protective layer may each have at least one of silicon nitride, aluminum nitride, or hafnium nitride.

[0017] Alternatively, in the above embodiment, the insulating layer may have an organic material.

[0018] Alternatively, in the above embodiment, a common layer is provided between the first EL layer, the second EL layer, the second protective layer, and the common electrode, and the common layer may have at least one of a hole injection layer, a hole transport layer, a hole blocking layer, an electron blocking layer, an electron transport layer, or an electron injection layer.

[0019] Alternatively, in the above embodiment, the distance between the side surface of the first EL layer and the side surface of the second EL layer may be a region of 1 μm or less.

[0020] Alternatively, in the above embodiment, the distance between the side surface of the first EL layer and the side surface of the second EL layer may have a region of 100 nm or less.

[0021] A display module having a display device according to one aspect of the present invention and at least one of a connector and an integrated circuit is also an aspect of the present invention.

[0022] An electronic device having a display module according to one aspect of the present invention and at least one of a battery, a camera, a speaker, and a microphone is also according to one aspect of the present invention.

[0023] Alternatively, in one aspect of the present invention, a first pixel electrode and a second pixel electrode are formed on an insulating surface; a first EL film and a first sacrificial film are sequentially formed on the first pixel electrode and the second pixel electrode; a first sacrificial layer and a first EL layer are formed by processing the first sacrificial film and the first EL film, respectively, having a region overlapping with the first pixel electrode; a first protective film is formed covering at least the side surface of the first EL layer and the side surface and top surface of the first sacrificial layer; a first protective layer is formed by processing the first protective film, having a region overlapping with the side surface of the first EL layer; a second EL film and a second sacrificial film are sequentially formed on the first sacrificial layer and the second pixel electrode; a second sacrificial layer and a second sacrificial film are formed by processing the second sacrificial film and the second EL film, having a region overlapping with the second pixel electrode. This is a method for manufacturing a display device, comprising: forming a first and second EL layer, respectively; forming a second protective film that covers at least the upper surface of the first sacrificial layer, the upper and side surfaces of the second sacrificial layer, the side surfaces of the first protective layer, and the side surfaces of the second EL layer; forming an insulating film on the second protective film; processing the insulating film to form an insulating layer between the first EL layer and the second EL layer; processing the second protective film to form a second protective layer between the first protective layer and the insulating layer, and between the second EL layer and the insulating layer; forming a third protective film on the first sacrificial layer, on the second sacrificial layer, and on the insulating layer; processing the third protective film to form a third protective layer on the insulating layer; removing the first and second sacrificial layers; and forming common electrodes on the first EL layer, on the second EL layer, and on the third protective layer.

[0024] Alternatively, in the above embodiment, a fourth protective film may be formed after the formation of the first protective film so as to have a region in contact with the first protective film, and a fifth protective film may be formed after the formation of the second protective film so as to have a region in contact with the second protective film.

[0025] Alternatively, in the above embodiment, the first protective film and the second protective film may be formed using the ALD method, and the third to fifth protective films may be formed using the sputtering method or the CVD method.

[0026] Alternatively, in the above embodiment, the insulating film may be formed using a spin coating method, a spray method, a screen printing method, or a paint method.

[0027] Alternatively, in the above embodiment, the insulating film may be processed using photolithography.

[0028] Alternatively, in the above embodiment, the first protective film, the second protective film, the fourth protective film, and the fifth protective film may be processed using a dry etching method.

[0029] Alternatively, in the above embodiment, before forming the common electrode, at least one of a hole injection layer, hole transport layer, hole blocking layer, electron blocking layer, electron transport layer, or electron injection layer may be formed as a common layer on the first EL layer, the second EL layer, and the insulating layer. [Effects of the Invention]

[0030] According to one aspect of the present invention, a display device with high display quality can be provided. According to one aspect of the present invention, a highly reliable display device can be provided. According to one aspect of the present invention, a display device with low power consumption can be provided. According to one aspect of the present invention, a display device that can be easily made high-resolution can be provided. According to one aspect of the present invention, a display device that combines high display quality and high resolution can be provided. According to one aspect of the present invention, a low-cost display device can be provided. According to one aspect of the present invention, a display device with high contrast can be provided. According to one aspect of the present invention, a display device having a novel configuration can be provided.

[0031] According to one aspect of the present invention, a method for manufacturing a display device with high display quality can be provided. According to one aspect of the present invention, a method for manufacturing a highly reliable display device can be provided. According to one aspect of the present invention, a method for manufacturing a display device with low power consumption can be provided. According to one aspect of the present invention, a method for manufacturing a display device that is easily made high-resolution can be provided. According to one aspect of the present invention, a method for manufacturing a display device that combines high display quality and high resolution can be provided. According to one aspect of the present invention, a method for manufacturing a display device with low cost can be provided. According to one aspect of the present invention, a method for manufacturing a display device with high contrast can be provided. According to one aspect of the present invention, a method for manufacturing a display device having a novel configuration can be provided.

[0032] Furthermore, the description of these effects does not preclude the existence of other effects. Moreover, one aspect of the present invention does not necessarily have to possess all of these effects. Other effects can be extracted from the description in the specification, drawings, claims, etc. [Brief explanation of the drawing]

[0033] [Figure 1] Figure 1 is a top view showing an example of the configuration of a display device. [Figure 2] Figures 2A, 2B, 2C1, 2C2, and 2D are cross-sectional views showing examples of the configuration of a display device. [Figure 3] Figures 3A and 3B are cross-sectional views showing examples of the configuration of a display device. [Figure 4] Figures 4A to 4F are top views showing examples of pixel configurations. [Figure 5] Figures 5A to 5E are top views showing examples of pixel configurations. [Figure 6] Figures 6A to 6D are cross-sectional views showing examples of methods for manufacturing a display device. [Figure 7] Figures 7A1, 7A2, 7B1, and 7B2 are cross-sectional views showing examples of methods for manufacturing a display device. [Figure 8] Figures 8A to 8C are cross-sectional views showing examples of methods for manufacturing a display device. [Figure 9]Figures 9A1, 9A2, 9B1, and 9B2 are cross-sectional views showing examples of methods for manufacturing a display device. [Figure 10] Figures 10A to 10C are cross-sectional views showing examples of methods for manufacturing a display device. [Figure 11] Figures 11A to 11C are cross-sectional views showing examples of methods for manufacturing a display device. [Figure 12] Figures 12A, 12B1, and 12B2 are cross-sectional views showing examples of methods for manufacturing a display device. [Figure 13] Figures 13A and 13B are cross-sectional views showing examples of methods for manufacturing a display device. [Figure 14] Figures 14A, 14B1, and 14B2 are cross-sectional views showing examples of methods for manufacturing a display device. [Figure 15] Figures 15A, 15B1, and 15B2 are cross-sectional views showing examples of methods for manufacturing a display device. [Figure 16] Figures 16A and 16B are cross-sectional views showing examples of methods for manufacturing a display device. [Figure 17] Figures 17A to 17D are cross-sectional views showing examples of the configuration of a display device. [Figure 18] Figures 18A to 18D are cross-sectional views showing examples of the configuration of a display device. [Figure 19] Figures 19A to 19D are cross-sectional views showing examples of the configuration of a display device. [Figure 20] Figures 20A to 20D are cross-sectional views showing examples of the configuration of a display device. [Figure 21] Figure 21 is a perspective view showing an example of a display device configuration. [Figure 22] Figure 22A is a cross-sectional view showing an example of the configuration of a display device. Figures 22B and 22C are cross-sectional views showing an example of the configuration of a transistor. [Figure 23] Figure 23 is a cross-sectional view showing an example of the configuration of a display device. [Figure 24] Figures 24A and 24B are perspective views showing example configurations of display modules. [Figure 25] Figure 25 is a cross-sectional view showing an example of the configuration of a display device. [Figure 26] Figure 26 is a cross-sectional view showing an example of the configuration of a display device. [Figure 27] Figure 27 is a cross-sectional view showing an example of the configuration of a display device. [Figure 28] Figure 28 is a cross-sectional view showing an example of the configuration of a display device. [Figure 29] Figures 29A to 29F show examples of the configuration of light-emitting elements. [Figure 30] Figures 30A and 30B show examples of electronic devices. [Figure 31] Figures 31A to 31D show examples of electronic devices. [Figure 32] Figures 32A to 32F show examples of electronic devices. [Figure 33] Figures 33A to 33F show examples of electronic devices. [Figure 34] Figures 34A to 34C are cross-sectional views showing the configuration of a sample according to an embodiment. Figure 34D is a diagram showing the configuration of the EL layer. [Figure 35] Figures 35A to 35E are cross-sectional views showing the method for preparing samples according to the embodiment. [Figure 36] Figures 36A to 36D are cross-sectional views showing the method for preparing samples according to the embodiment. [Figure 37] Figures 37A to 37E are cross-sectional views showing the method for preparing samples according to the embodiment. [Figure 38] Figure 38 is a graph showing the brightness-voltage characteristics of the sample according to the embodiment. [Figure 39] Figure 39 is a graph showing the current efficiency-luminance characteristics of the sample according to the embodiment. [Figure 40] Figure 40 is a graph showing the change in normalized brightness over time for the sample according to the example. [Modes for carrying out the invention]

[0034] The embodiments will be described below with reference to the drawings. However, it will be readily apparent to those skilled in the art that the embodiments can be implemented in many different ways, and their form and details can be modified in various ways without departing from the spirit and scope thereof. Therefore, the present invention is not to be construed as being limited to the contents of the following embodiments.

[0035] In the configuration of the invention described below, the same reference numerals are used in common across different drawings for identical parts or parts having similar functions, and repeated explanations are omitted. Furthermore, when referring to similar functions, the hatch patterns are the same, and reference numerals may not be assigned.

[0036] In the figures described herein, the size of each component, the thickness of the layers, or the area may be exaggerated for clarity. Therefore, the scale is not necessarily limited to those figures.

[0037] Furthermore, the ordinal numbers such as "the first" and "the second" used in this specification are added to avoid confusion of constituent elements and do not imply any numerical limitation.

[0038] Furthermore, in this specification, the terms "film" and "layer" may be interchangeable depending on the circumstances. For example, the terms "conductive layer" or "insulating layer" may be interchangeable with the terms "conductive film" or "insulating film."

[0039] In this specification, the term "EL layer" refers to a layer (also called a light-emitting layer) provided between a pair of electrodes of a light-emitting element and containing at least a light-emitting substance, or a laminate including a light-emitting layer.

[0040] In this specification, a display panel, which is one form of a display device, has the function of displaying (outputting), for example, an image on its display surface. Therefore, a display panel is one form of an output device.

[0041] Furthermore, in this specification, a display panel on which a connector such as an FPC (Flexible Printed Circuit) or TCP (Tape Carrier Package) is attached, or on which an IC is mounted on the board using a COG (Chip On Glass) method, may be referred to as a display panel module, a display module, or simply a display panel, etc.

[0042] (Embodiment 1) This embodiment describes an example of the configuration of a display device according to one aspect of the present invention, and an example of a method for manufacturing the display device.

[0043] One aspect of the present invention is a display device having light-emitting elements (also called light-emitting devices). The display device has two light-emitting elements that emit light of at least different colors. Each light-emitting element has a pair of electrodes and an EL layer between them. As the light-emitting elements, electroluminescent elements such as organic EL elements or inorganic EL elements can be used. In addition, light-emitting diodes (LEDs) can be used. In one aspect of the present invention, the light-emitting elements are preferably organic EL elements (organic electroluminescent elements). The 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.

[0044] When creating EL layers for different colored light-emitting elements, it is known that the EL layer is formed by a vapor deposition method using a shadow mask such as a metal mask. However, with this method, deviations from the design occur in the shape and position of island-like organic films due to various influences such as the precision of the metal mask, the misalignment between the metal mask and the substrate, the deflection of the metal mask, and, for example, the spreading of the contour of the deposited film due to vapor scattering, making it difficult to achieve high resolution and high aperture ratio. In addition, dust may be generated during vapor deposition due to materials adhering to the metal mask. Such dust may cause pattern defects in the light-emitting elements. There is also a possibility of short circuits caused by the dust. Furthermore, a cleaning process for materials adhering to the metal mask is required. For this reason, measures have been taken to artificially increase resolution (also called pixel density) by applying special pixel arrangement methods such as PenTile arrangements.

[0045] One aspect of the present invention involves processing the EL layer 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 resolution and a large aperture ratio, which has been difficult to achieve until now. Furthermore, since the EL layer can be differentiated, it is possible to realize a display device with extremely vivid colors, high contrast, and high display quality.

[0046] In this specification, devices fabricated using a metal mask or an FMM (Fine Metal Mask, a high-resolution metal mask) may be referred to as MM (Metal Mask) structured devices. Furthermore, in this specification, devices fabricated without using a metal mask or FMM may be referred to as MML (Metal Maskless) structured devices.

[0047] For simplicity, this section describes the process of creating two different colored light-emitting elements (a first light-emitting element and a second light-emitting element). First, a first pixel electrode and a second pixel electrode are formed on a substrate. Next, a first EL film and a first sacrificial film are formed sequentially on the first and second pixel electrodes, respectively. Then, a resist mask is formed on the first sacrificial film. Subsequently, the first sacrificial film and the first EL film are processed using the resist mask to form a first sacrificial layer and a first EL layer, respectively, which have regions overlapping with the first pixel electrode. In this specification, the sacrificial film may be referred to as a mask film, and the sacrificial layer may be referred to as a mask layer.

[0048] Next, a first protective film is formed that covers the sides of the first EL layer, the sides and top of the first sacrificial layer, and the sides and top of the second pixel electrode. Subsequently, the first protective film is processed to form a first protective layer having a region that overlaps with the sides of the first EL layer. The first protective film can be processed using anisotropic etching, such as dry etching.

[0049] Next, a second EL film and a second sacrificial film are formed sequentially on the first sacrificial layer and the second pixel electrode. Subsequently, a resist mask is formed on the second sacrificial film. Then, using the resist mask, the second sacrificial film and the second EL film are processed to form a second sacrificial layer and a second EL layer, respectively, which have a region overlapping with the second pixel electrode.

[0050] Next, a second protective film is formed that covers the top and sides of the first sacrificial layer, the top and sides of the second sacrificial layer, the sides of the first protective layer, and the sides of the second EL layer.

[0051] Next, an insulating film is formed on the second protective film. Subsequently, an insulating layer is formed between the first EL layer and the second EL layer by processing the insulating film. The insulating film can be made of a photosensitive material, for example, a photosensitive resin. In this case, the insulating film can be processed using photolithography to form the insulating layer between the first EL layer and the second EL layer.

[0052] Next, the second protective film is processed to form a second protective layer between the first protective layer and the insulating layer, between the second EL layer and the insulating layer, and between the substrate and the insulating layer. The second protective film can be processed using anisotropic etching methods such as dry etching, similar to the first protective film.

[0053] Next, a third protective film is formed on the first sacrificial layer, the second sacrificial layer, and the insulating layer. Subsequently, the third protective film is processed to form a third protective layer on the insulating layer.

[0054] Next, the first sacrificial layer and the second sacrificial layer are removed. Finally, by forming a common electrode on the first EL layer, the second EL layer, and the third protective layer, two-color light-emitting elements can be created. Specifically, a first light-emitting element having a first pixel electrode, a first EL layer, and a common electrode, and a second light-emitting element having a second pixel electrode, a second EL layer, and a common electrode can be created.

[0055] Furthermore, by repeating the process from forming the first EL film to forming the first protective layer after forming the first protective layer, it is possible to create three or more different colored light-emitting elements, thereby realizing a display device having three or four or more colored light-emitting elements.

[0056] As described above, in one embodiment of the present invention, an insulating layer is provided between the first EL layer and the second EL layer. This insulating layer fills the gap between the first light-emitting element and the second light-emitting element. Therefore, the surface on which the common electrode is provided can be made less uneven, and thus the breakage (step breakage) of the common electrode can be suppressed. As a result, one embodiment of the present invention can be made into a highly reliable display device.

[0057] In this case, when an organic insulating material such as a photosensitive resin is used as the insulating layer provided between the first EL layer and the second EL layer, the insulating layer may contain oxygen or water. If oxygen or water penetrates the EL layer, the light-emitting element having the EL layer may deteriorate. Therefore, in a display device according to one aspect of the present invention, a protective layer with high barrier properties against oxygen and water is provided so as to surround the insulating layer provided between the first EL layer and the second EL layer. This makes it possible to suppress the penetration of impurities such as oxygen and water into the EL layer. Thus, a display device according to one aspect of the present invention can be made into a highly reliable display device. In the above example, a second protective layer is provided so as to cover the sides and bottom surface of the insulating layer provided between the first EL layer and the second EL layer, and a third protective layer is provided so as to cover the top surface of the insulating layer. As a result, the insulating layer provided between the first EL layer and the second EL layer can be surrounded by the second protective layer and the third protective layer. As a protective layer with high barrier properties against oxygen and water, for example, an inorganic insulating material can be used, such as an inorganic nitride film. As the inorganic nitride, at least one of silicon nitride, aluminum nitride, and hafnium nitride can be used.

[0058] In the above-described manufacturing method, the first protective film and the second protective film can be a laminated structure of two or more layers. For example, the first protective film and the second protective film can be a two-layer laminated film formed by depositing the first layer using a method with high coverage and the second layer using a method with low coverage. For example, the first protective film and the second protective film can be a two-layer laminated film formed by depositing the first layer using the ALD method and the second layer using the sputtering method or the chemical vapor deposition (CVD) method. As a result, the first protective layer and the second protective layer can be made thicker while covering the steps, thus effectively suppressing the penetration of impurities such as oxygen and water into the first EL layer and the second EL layer. Therefore, a display device according to one aspect of the present invention can be a highly reliable display device.

[0059] Furthermore, as mentioned above, it is preferable from the viewpoint of the reliability of the display device to prevent impurities from penetrating the EL layer. If impurities adhere to the surface of the EL layer, these impurities may penetrate into the interior of the EL layer, potentially reducing the reliability of the display device. Therefore, it is preferable to remove impurities adhering to the surface of the first EL layer after its formation and before the formation of the first protective film covering the first EL layer, in order to improve the reliability of the display device. Similarly, it is preferable to remove impurities adhering to the surface of the second EL layer after its formation and before the formation of the second protective film covering the second EL layer. For example, impurities adhering to the surface of the first EL layer can be removed by placing the substrate on which the first EL layer is formed under an inert gas atmosphere. Similarly, impurities adhering to the surface of the second EL layer can be removed by placing the substrate on which the second EL layer is formed under an inert gas atmosphere. As the inert gas, one or more selected from, for example, Group 18 elements (typically helium, neon, argon, xenon, and krypton, etc.) and nitrogen can be used.

[0060] Furthermore, if the EL layer is exposed to air, for example, oxygen and impurities such as water contained in the air may penetrate into the interior of the EL layer. Here, after the formation of the first EL layer, the surface of the first EL layer is exposed until the first protective film is formed. Therefore, it is preferable to perform the processes from processing the first EL film to forming the first protective film in the same apparatus. This makes it possible to form the first protective film covering the first EL layer without exposing the first EL layer to air after processing the first EL film to form the first EL layer. Similarly, it is preferable to perform the processing of the second EL film and the formation of the second protective film in the same apparatus. As a result, it is possible to suppress the penetration of impurities contained in the air into the interior of the EL layer and improve the reliability of the display device. It is also preferable to perform other processes in the same apparatus, as this can suppress exposure of the display device components to air during the manufacturing process and increase the throughput in the manufacturing of the display device.

[0061] When EL layers of different colors are adjacent, it is difficult to reduce the spacing between adjacent EL layers to less than 10 μm using, for example, a formation method using a metal mask. However, with the method described above, the spacing can be narrowed to 3 μm or less, 2 μm or less, or even 1 μm or less. For example, by using an exposure apparatus for LSIs, the spacing can be narrowed to 500 nm or less, 200 nm or less, 100 nm or less, and even 50 nm or less. This significantly reduces the area of ​​the non-emitting region that may exist between two light-emitting elements, making it possible to approach an aperture ratio of 100%. For example, the aperture ratio can be 50% or more, 60% or more, 70% or more, 80% or more, and even 90% or more, and it is possible to achieve less than 100%.

[0062] Furthermore, the pattern of the EL layer itself can be made extremely small compared to when a metal mask is used. Also, for example, when a metal mask is used to create different EL layers, variations in thickness occur between the center and edges of the pattern, so the effective area that can be used as an emitting region is small relative to the total area of ​​the pattern. On the other hand, in the above manufacturing method, the pattern is formed by processing a film deposited to a uniform thickness, so the thickness can be made uniform within the pattern, and even if the pattern is fine, almost the entire area can be used as an emitting region. Therefore, the above manufacturing method can achieve both high resolution and a high aperture ratio.

[0063] Thus, the above manufacturing method makes it possible to realize a display device that integrates fine light-emitting elements, eliminating the need to artificially increase resolution by applying special pixel arrangement methods such as the pentile method. Therefore, it is possible to realize a display device with a resolution of 500 ppi or more, 1000 ppi or more, 2000 ppi or more, 3000 ppi or more, and even 5000 ppi or more, using a so-called stripe arrangement in which R, G, and B are each arranged in one direction.

[0064] In the following section, a more specific configuration example and manufacturing method example of a display device according to one aspect of the present invention will be described with reference to the drawings.

[0065] [Configuration Example_1] Figure 1 shows a top view of a display device 100 according to one embodiment of the present invention. The display device 100 has multiple red-emitting light-emitting elements 110R, green-emitting light-emitting elements 110G, and blue-emitting light-emitting elements 110B. In Figure 1, the labels R, G, and B are added within the light-emitting area of ​​each light-emitting element to simplify the distinction between them.

[0066] In this specification, for example, light-emitting elements 110R, 110G, and 110B may be collectively referred to as light-emitting element 110. For example, when referring to light-emitting element 110, it refers to some or all of light-emitting elements 110R, 110G, and 110B. The same description applies to other elements.

[0067] The light-emitting elements 110R, 110G, and 110B are each arranged in a matrix. Pixel 103, shown in Figure 1, exhibits a so-called stripe arrangement, where light-emitting elements of the same color are arranged in one direction. However, the arrangement method of the light-emitting elements is not limited to this; other arrangement methods such as delta arrangement or zigzag arrangement may also be applied, and a pentile arrangement can also be used.

[0068] It is preferable to use EL elements such as organic EL elements or inorganic EL elements as the light-emitting element 110R, light-emitting element 110G, and light-emitting element 110B.

[0069] Figure 1 also shows the connecting electrode 111C and the common electrode 115, with the common electrode 115 indicated by a dashed line. The connecting electrode 111C is supplied with a potential (e.g., anode potential or cathode potential) to the common electrode 115. The connecting electrode 111C is provided outside the display area where the light-emitting elements 110R are arranged. For example, the connecting electrode 111C can be provided along the outer perimeter of the display area. For example, the connecting electrode 111C may be provided along one side of the outer perimeter of the display area, or along two or more sides of the outer perimeter of the display area. That is, if the top surface shape of the display area is rectangular, the top surface shape of the connecting electrode 111C can be strip-shaped, L-shaped, U-shaped (angle bracket-shaped), or frame-shaped, etc.

[0070] Figure 2A is a cross-sectional view corresponding to the dashed line A1-A2 in Figure 1. Figure 2B is a cross-sectional view corresponding to the dashed line B1-B2 in Figure 1. Figure 2C1 is a cross-sectional view corresponding to the dashed line C1-C2 in Figure 1.

[0071] Figure 2A shows an example of the cross-sectional configuration of the light-emitting element 110R, light-emitting element 110G, and light-emitting element 110B. Figure 2B also shows an example of the cross-sectional configuration of the light-emitting element 110G. The light-emitting element 110 is provided on a layer 101 containing a transistor. The layer 101 containing the transistor is provided on a substrate (not shown).

[0072] A layered structure can be applied in which, for example, multiple transistors are provided in the transistor-containing layer 101, and an insulating layer is provided to cover these transistors. Here, as shown in Figures 2A and 2B, the transistor-containing layer 101 may have recesses between adjacent light-emitting elements 110. For example, recesses may be provided in the insulating layer located on the outermost surface of the transistor-containing layer 101. Note that the transistor-containing layer 101 may not have recesses between adjacent light-emitting elements 110.

[0073] The layer 101 containing the transistor preferably includes, for example, a pixel circuit, a scan line driving circuit (gate driver), and a signal line driving circuit (source driver). In addition to the above, it may also include an arithmetic circuit or a memory circuit.

[0074] The light-emitting element 110R has a pixel electrode 111R and an EL layer 112R on the pixel electrode 111R. The light-emitting element 110G has a pixel electrode 111G and an EL layer 112G on the pixel electrode 111G. The light-emitting element 110B has a pixel electrode 111B and an EL layer 112B on the pixel electrode 111B. Furthermore, the light-emitting elements 110R, 110G, and 110B have a common layer 114 on the EL layer 112R, on the EL layer 112G, and on the EL layer 112B, and a common electrode 115 on the common layer 114. The common layer 114 and the common electrode 115 are provided as a continuous layer common to each light-emitting element 110.

[0075] Each of the EL layers 112R, 112G, and 112B has an emissive layer. The emissive layer is a layer containing an emissive material. The emissive layer may contain one or more types of emissive materials. As the emissive material, a material that exhibits an emission color such as blue, purple, blue-violet, green, yellow-green, yellow, orange, or red may be used as appropriate. In addition, a material that emits near-infrared light may be used as the emissive material. For example, the emissive layer of EL layer 112R may contain an emissive material that exhibits red light. The emissive layer of EL layer 112G may contain an emissive material that exhibits green light. Furthermore, the emissive layer of EL layer 112B may contain an emissive material that exhibits blue light.

[0076] Examples of luminescent materials include fluorescent materials, phosphorescent materials, TADF materials, and quantum dot materials.

[0077] Furthermore, as quantum dot materials, colloidal quantum dot materials, alloy-type quantum dot materials, core-shell type quantum dot materials, or core-type quantum dot materials can be used. Materials containing elemental groups from groups 12 and 16, 13 and 15, or 14 and 16 may also be used. In addition, quantum dot materials containing elements such as cadmium, selenium, zinc, sulfur, phosphorus, indium, tellurium, lead, gallium, arsenic, or aluminum may also be used.

[0078] 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.

[0079] Examples of phosphorescent materials include organometallic complexes (especially iridium complexes) having a 4H-triazole skeleton, 1H-triazole skeleton, imidazole skeleton, pyrimidine skeleton, pyrazine skeleton, or pyridine skeleton; organometallic complexes (especially iridium complexes) using phenylpyridine derivatives having electron-withdrawing groups as ligands; platinum complexes; and rare earth metal complexes.

[0080] The light-emitting layer may contain one or more types of organic compounds (host material, assist material, etc.) in addition to the light-emitting substance (guest material). One or more of the organic compounds may be hole-transporting materials and / or electron-transporting materials. Alternatively, one or more of the organic compounds may be bipolar materials or TADF materials.

[0081] The light-emitting layer preferably comprises, for example, a phosphorescent material and a combination of a hole-transporting material and an electron-transporting material that readily forms an excitation complex. This configuration allows for efficient emission using ExTET (Exciplex-Triplet Energy Transfer), which is energy transfer from the excitation complex to the light-emitting substance (phosphorescent material). By selecting a combination that forms an excitation complex that exhibits emission overlapping with the wavelength of the lowest-energy absorption band of the light-emitting substance, energy transfer becomes smoother, and light emission can be obtained efficiently. This configuration simultaneously achieves high efficiency, low-voltage operation, and a long lifespan for the light-emitting device.

[0082] The EL layer 112R, EL layer 112G, and EL layer 112B may further include layers other than the light-emitting layer, such as a material with high hole injection properties, a material with high hole transport properties, a hole blocking material, a material with high electron transport properties, a material with high electron injection properties, an electron blocking material, or a bipolar material (a material with high electron transport and hole transport properties).

[0083] The light-emitting element can be made from either low-molecular-weight compounds or high-molecular-weight compounds, and may also contain inorganic compounds. The layers constituting the light-emitting element can be formed by methods such as vapor deposition (including vacuum deposition), transfer, printing, inkjet, or coating.

[0084] For example, EL layer 112R, EL layer 112G, and EL layer 112B may each have one or more of the following: a hole injection layer, a hole transport layer, a hole blocking layer, an electron blocking layer, an electron transport layer, and an electron injection layer.

[0085] Preferably, the EL layer 112R, EL layer 112G, and EL layer 112B each have an emissive layer and a carrier transport layer on the emissive layer. This suppresses exposure of the emissive layer to the outermost surface during the manufacturing process of the display device 100, thereby reducing damage to the emissive layer. This improves the reliability of the light-emitting element. Therefore, the display device 100 can be made into a highly reliable display device.

[0086] The hole injection layer is a layer that injects holes from the anode into the hole transport layer, and is a layer containing a material with high hole injection capabilities. Examples of materials with high hole injection capabilities include aromatic amine compounds and composite materials containing hole transport materials and acceptor materials (electron-accepting materials).

[0087] 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 containing a hole-transporting material. The hole-transporting material is 1 × 10⁻¹⁶ -6 cm 2 Materials having a hole mobility of / Vs or higher are preferred. However, other materials can also be used as long as their hole transportability is higher than their electron transportability. Preferred hole transport materials are π-electron-rich heteroaromatic compounds (e.g., carbazole derivatives, thiophene derivatives, or furan derivatives), or aromatic amines (compounds having an aromatic amine skeleton), which are materials with high hole transportability.

[0088] The electron transport layer is a layer that transports electrons injected from the cathode by the electron injection layer to the light-emitting layer. The electron transport layer is a layer containing an electron-transporting material. The electron-transporting material is 1 × 10⁻¹⁶ -6 cm 2 Materials having an electron mobility of / Vs or higher are preferred. As electron-transporting materials, in addition to metal complexes having a quinoline skeleton, metal complexes having a benzoquinoline skeleton, metal complexes having an oxazole skeleton, or metal complexes having a thiazole skeleton, materials with high electron transport properties such 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, or other π-electron-deficient heteroaromatic compounds containing nitrogen-containing heteroaromatic compounds can be used. Other materials can also be used as long as their electron transport properties are higher than their hole transport properties.

[0089] The electron injection layer is a layer that injects electrons from the cathode to the electron transport layer, and is a layer containing a material with high electron injection capabilities. Alkali metals, alkaline earth metals, or compounds thereof can be used as materials with high electron injection capabilities. Composite materials containing both electron transport materials and donor materials (electron-donating materials) can also be used as materials with high electron injection capabilities.

[0090] Examples of electron injection layers include lithium, cesium, ytterbium, lithium fluoride (LiF), cesium fluoride (CsF), and calcium fluoride (CaF). x (where X is any number), 8-(quinolinolato)lithium (abbreviation: Liq), 2-(2-pyridyl)phenolatrium (abbreviation: LiPP), 2-(2-pyridyl)-3-pyridinolatrium (abbreviation: LiPPy), 4-phenyl-2-(2-pyridyl)phenolatrium (abbreviation: LiPPP), lithium oxide (LiO x ), or alkali metals such as cesium carbonate, alkaline earth metals, or compounds thereof can be used. Furthermore, the electron injection layer may be a multilayer structure of two or more layers. For example, the multilayer structure may consist of lithium fluoride as the first layer and ytterbium as the second layer.

[0091] Alternatively, an electron-transporting material may be used as the electron injection layer. For example, a compound having a lone pair of electrons and an electron-deficient heteroaromatic ring can be used as the electron-transporting material. Specifically, a compound having at least one of a pyridine ring, a diazine ring (pyrimidine ring, pyrazine ring, and pyridazine ring), and a triazine ring can be used.

[0092] Furthermore, it is preferable that the lowest unoccupied molecular orbital (LUMO) of an organic compound containing a lone pair of electrons is between -3.6 eV and -2.3 eV. In general, the highest occupied molecular orbital (HOMO) level and the LUMO level of an organic compound can be estimated by methods such as cyclic voltammetry (CV), photoelectron spectroscopy, optical absorption spectroscopy, or inverse photoelectron spectroscopy.

[0093] For example, 4,7-diphenyl-1,10-phenanthroline (abbreviated as BPhen), 2,9-bis(naphthalene-2-yl)-4,7-diphenyl-1,10-phenanthroline (abbreviated as NBPhen), diquinoxalino[2,3-a:2',3'-c]phenazine (abbreviated as HATNA), or 2,4,6-tris[3'-(pyridine-3-yl)biphenyl-3-yl]-1,3,5-triazine (abbreviated as TmPPPyTz) can be used in organic compounds containing lone pairs of electrons. NBPhen has a higher glass transition temperature (Tg) and superior heat resistance compared to BPhen.

[0094] The common layer 114 is preferably a layer having one or more of the following: a hole injection layer, a hole transport layer, a hole block layer, an electron block layer, an electron transport layer, or an electron injection layer. For example, in a light-emitting element where the pixel electrode 111 is the anode and the common electrode is the cathode, the common layer 114 can be configured to have an electron injection layer, or to have both an electron injection layer and an electron transport layer. Also, in a light-emitting element where the pixel electrode 111 is the cathode and the common electrode is the anode, the common layer 114 can be configured to have a hole injection layer, or to have both a hole injection layer and a hole transport layer. Here, for example, if the common layer 114 has an electron injection layer, the EL layer 112R, EL layer 112G, and EL layer 112B do not need to have an electron injection layer. For example, the EL layer 112R, EL layer 112G, and EL layer 112B can have a configuration comprising a hole injection layer, a hole transport layer on the hole injection layer, an emissive layer on the hole transport layer, and an electron transport layer on the emissive layer. Also, for example, if the common layer 114 has a hole injection layer, the EL layers 112R, EL layer 112G, and EL layer 112B do not need to have a hole injection layer.

[0095] As mentioned above, the common layer 114 is provided as a continuous layer common to each light-emitting element 110. Therefore, the common layer 114 does not need to be processed by etching, for example. Consequently, by configuring the display device 100 to have a common layer 114, the manufacturing process of the display device 100 can be simplified, and thus the manufacturing cost of the display device 100 can be reduced. Thus, the display device 100 can be made into a low-cost display device.

[0096] Furthermore, the common layer 114 and the common electrode 115 can be formed continuously without any etching or other processes in between. Therefore, the interface between the common layer 114 and the common electrode 115 can be made into a clean surface. This makes the display device 100 a highly reliable display device. Note that the display device 100 does not necessarily have a common layer 114. In this case, for example, in a light-emitting element in which the pixel electrode 111 is the anode and the common electrode is the cathode, the EL layer 112R, EL layer 112G, and EL layer 112B can be configured in which an electron injection layer is provided on the electron transport layer.

[0097] A conductive layer that is transparent to visible light is used on either the pixel electrode 111 or the common electrode 115, and a conductive layer that is reflective is used on the other. By making the pixel electrode 111 transparent and the common electrode 115 reflective, a bottom-emission type display device can be made, and conversely, by making the pixel electrode 111 reflective and the common electrode 115 transparent, a top-emission type display device can be made. Furthermore, by making both the pixel electrode 111 and the common electrode 115 transparent, a dual-emission type display device can also be made.

[0098] When the pixel electrode 111 is a conductive layer that is reflective to visible light, for example, silver, aluminum, titanium, tantalum, molybdenum, platinum, gold, titanium nitride, or tantalum nitride can be used as the pixel electrode 111. Alternatively, an alloy can be used as the pixel electrode 111. For example, an alloy containing silver can be used. As an alloy containing silver, for example, an alloy containing silver, palladium, and copper can be used. Alternatively, for example, an alloy containing aluminum can be used. Furthermore, two or more layers of these materials may be used in a laminated structure.

[0099] Furthermore, the pixel electrode 111 can be a laminated structure in which a conductive layer that is transparent to visible light is provided on a conductive layer that is reflective to visible light. Conductive oxides 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 can be used as the conductive material that is transparent to visible light. Alternatively, an oxide of a conductive material that is reflective to visible light may be used as the conductive material that is transparent to visible light, and this oxide can be formed, for example, by oxidizing the surface of a conductive material that is reflective to visible light. Specifically, for example, titanium oxide may be used. Titanium oxide can be formed, for example, by oxidizing the surface of titanium.

[0100] By providing an oxide on the surface of the pixel electrode 111, oxidation reactions with the pixel electrode 111 during the formation of the EL layer 112 can be suppressed, for example.

[0101] Furthermore, by providing the pixel electrode 111 with a laminated structure in which a conductive layer that is transparent to visible light is placed on a conductive layer that is reflective to visible light, the conductive layer that is transparent to visible light can be made to function as an optical adjustment layer.

[0102] The optical path length can be adjusted by having an optical adjustment layer in the pixel electrode 111. The optical path length in the light-emitting element 110 corresponds, for example, to the sum of the thickness of the optical adjustment layer and the thickness of the layer provided below the layer containing the luminescent compound in the EL layer 112.

[0103] In the light-emitting element 110, by using a microcavity structure (micro-resonator structure) to vary the optical path length, it is possible to intensify light of a specific wavelength. This makes it possible to realize a display device with improved color purity.

[0104] For example, a microcavity structure can be realized by varying the thickness of the EL layer 112 in each light-emitting element 110. For instance, the EL layer 112R of the light-emitting element 110R that emits the longest wavelength light can be the thickest, and the EL layer 112B of the light-emitting element 110B that emits the shortest wavelength light can be the thinnest. However, this is not limited to this configuration, and the thickness of each EL layer 112 can be adjusted by considering the wavelength of light emitted by each light-emitting element 110, the optical properties of the layers constituting the light-emitting element 110, and the electrical properties of the light-emitting element 110.

[0105] For the conductive layer that is reflective to visible light, it is preferable to use aluminum or silver, which have high reflectivity. In particular, aluminum is suitable for manufacturing high-resolution display devices because it is easy to microfabricate.

[0106] For the conductive layer that is transparent to visible light, it is preferable to use a transparent oxide conductive material. However, if, for example, a transparent oxide conductive material containing indium is provided in direct contact with aluminum, the aluminum may corrode in a later process. Therefore, to prevent corrosion, it is preferable to use aluminum in a layer that does not come into contact with the transparent oxide conductive film containing indium. For example, the pixel electrode 111 can have a three-layer laminated structure consisting of a layer using aluminum, a layer using titanium oxide, and a layer using indium tin oxide containing silicon.

[0107] In this case, when forming the pixel electrode 111, it is preferable to continuously deposit an aluminum film and a titanium oxide film. If the aluminum film is deposited and then exposed to the atmosphere before depositing the titanium oxide film, there is a risk that the aluminum film will spontaneously oxidize due to exposure to the atmosphere. By depositing the titanium oxide film without exposing the aluminum film to the atmosphere after depositing the aluminum film, the oxidation of aluminum can be suppressed.

[0108] Furthermore, if exposure to the atmosphere is necessary after forming the aluminum film but before forming the titanium oxide film, it is preferable to form the other film on the aluminum film before exposure to the atmosphere. This suppresses oxidation of the aluminum film due to exposure to the atmosphere. The thickness of the other film can be made extremely thin. For example, a titanium film may be formed on the aluminum film, and then, after exposure to the atmosphere, a titanium oxide film may be formed on the titanium film.

[0109] Alternatively, if there is concern that the surface of the aluminum film is oxidized, the oxide film on the surface of the aluminum film may be removed by reverse sputtering. For example, an aluminum film may be formed, exposed to the atmosphere, then the oxide film on the surface of the aluminum film may be removed by reverse sputtering, and then a titanium oxide film may be formed.

[0110] Methods for forming a titanium oxide film include reactive sputtering using a titanium target and oxygen gas, and sputtering using a titanium oxide target and an inert gas (e.g., argon gas). However, when oxygen gas is used, the surface of the aluminum film may be exposed to the oxygen gas and oxidized. Therefore, it is preferable to form the film in contact with the aluminum film without using oxygen gas. For this reason, it is preferable to form the titanium oxide film using sputtering with a titanium oxide target and an inert gas (e.g., argon gas).

[0111] The common electrode 115 can be a conductive layer that is translucent to visible light. For example, conductive oxides such as indium oxide, indium tin oxide, indium zinc oxide, zinc oxide, and zinc oxide containing gallium, or graphene can be used for the common electrode 115. Alternatively, metallic materials such as gold, silver, platinum, magnesium, nickel, tungsten, chromium, molybdenum, iron, cobalt, copper, palladium, or titanium, or alloy materials containing such metallic materials, can be used for the common electrode 115. Alternatively, nitrides of such metallic materials (e.g., titanium nitride) may be used for the common electrode 115. When using metallic materials or alloy materials (or their nitrides), it is preferable to make them thin enough to be translucent. Furthermore, a laminated film of the above materials can be used as the conductive layer. For example, using a laminated film of a silver-magnesium alloy and indium tin oxide for the common electrode 115 is preferable because it can improve the conductivity of the common electrode 115.

[0112] Here, for example, between the EL layer 112R and the EL layer 112G, a protective layer 131 is provided having a region that overlaps with the side surface of the EL layer 112R, and another protective layer 131 has a region that overlaps with the side surface of the EL layer 112G. Similarly, protective layers 131 are provided between other EL layers 112. Furthermore, a protective layer 131 having a region that overlaps with the side surface of the pixel electrode 111 can be provided.

[0113] The protective layer 131 is preferably a layer with high barrier properties against oxygen and water. This prevents impurities such as oxygen and water from entering the interior from the sides of the EL layer 112. Therefore, degradation of the light-emitting element 110 is suppressed, and the display device 100 can be made into a highly reliable display device.

[0114] As the protective layer 131, an inorganic insulating material can be used, and it can be a layer containing oxides or nitrides such as silicon oxide, silicon oxide nitride, silicon nitride, silicon oxide, aluminum oxide, aluminum oxide nitride, and hafnium oxide. It is preferable that the protective layer 131 be a film type without pinholes and have a film thickness.

[0115] In this specification, "oxide nitride" refers to a material in which the oxygen content is greater than the nitrogen content, and "nitride oxide" refers to a material in which the nitrogen content is greater than the oxygen content. For example, when "silicon oxynitride" is written, it refers to a material in which the oxygen content is greater than the nitrogen content, and when "silicon nitride oxide" is written, it refers to a material in which the nitrogen content is greater than the oxygen content.

[0116] Figures 2A and 2B show an example in which the uppermost surface of the protective layer 131, which has a region overlapping with the side surface of the EL layer 112, is located above the upper surface of the EL layer 112. However, the present invention is not limited to this. For example, the height of the uppermost surface of the protective layer 131, which has a region overlapping with the side surface of the EL layer 112, may be equal to the height of the upper surface of the EL layer 112. Alternatively, the uppermost surface of the protective layer 131, which has a region overlapping with the side surface of the EL layer 112, may be located below the upper surface of the EL layer 112.

[0117] In this case, increasing the spacing between adjacent EL layers 112 may reduce the aperture ratio of the pixels 103. On the other hand, decreasing the spacing between adjacent EL layers 112 may result in the protective layer 131 not being formed to cover the sides of the EL layers 112, reducing the barrier effect of the protective layer 131 and making it easier for impurities to penetrate into the interior from the sides of the EL layers 112. Therefore, it is preferable that the spacing between the sides of one EL layer 112 and the adjacent EL layer 112 has a region of 3 nm to 200 nm, more preferably a region of 3 nm to 150 nm, more preferably a region of 5 nm to 150 nm, more preferably a region of 5 nm to 100 nm, more preferably a region of 10 nm to 100 nm, and more preferably a region of 10 nm to 50 nm. By setting the spacing between the sides of one EL layer 112 and the adjacent EL layer 112 within the above range, the display device 100 can be made into a display device with a high aperture ratio and high reliability.

[0118] An insulating layer 132 is provided between adjacent light-emitting elements 110. The insulating layer 132 is located between each EL layer 112 of the light-emitting element 110. For example, the insulating layer 132 is provided between two EL layers 112 that exhibit different colors. Alternatively, the insulating layer 132 is provided between two EL layers 112 that exhibit the same color. Alternatively, the insulating layer 132 may be provided between two EL layers 112 that exhibit different colors, but not between two EL layers 112 that exhibit the same color. Furthermore, the insulating layer 132 can be located between each pixel electrode 111 of the light-emitting element 110.

[0119] Furthermore, the insulating layer 132 is arranged between the EL layers 112 between adjacent pixels so as to have a mesh-like (or grid-like, or matrix-like) shape when viewed from above.

[0120] By providing an insulating layer 132 between EL layers 112 exhibiting different colors, contact between EL layers 112R, 112G, and 112B can be suppressed. This prevents current from flowing through two adjacent EL layers 112 and causing unintended light emission. Therefore, contrast can be increased, and the display device 100 can be made into a display device with high display quality. Furthermore, by providing an insulating layer 132 between each pixel electrode 111, contact between the pixel electrodes 111 can be suppressed. This prevents short circuits between the pixel electrodes 111. Therefore, the display device 100 can be made into a highly reliable display device.

[0121] Furthermore, by providing an insulating layer 132 between adjacent light-emitting elements 110, the step difference caused by the region where the EL layer 112 is provided and the region where the EL layer 112 is not provided can be flattened. As a result, the coverage of the common electrode 115 can be improved compared to the case where an insulating layer 132 is not provided between adjacent light-emitting elements 110, for example, when an air gap is formed. Therefore, it is possible to suppress the occurrence of step breaks in the common electrode 115 and the resulting connection failure. In addition, it is possible to suppress the local thinning of the common electrode 115 due to the step difference and the resulting increase in electrical resistance. As a result, the display device 100 can be made into a highly reliable display device.

[0122] Furthermore, if the insulating layer 132 is not provided between adjacent light-emitting elements 110 of the same color, and is formed only between light-emitting elements 110 of different colors, the insulating layer 132 can have a stripe shape when viewed from above. By making the insulating layer 132 stripe-shaped, the space required to form the insulating layer 132 is reduced compared to when the insulating layer 132 has a grid shape. Therefore, the aperture ratio of the display device 100 can be increased. In addition, when the insulating layer 132 has a stripe shape, adjacent EL layers 112 of the same color may be processed into strips so that they are continuous in the column direction.

[0123] The insulating layer 132 can preferably be an insulating layer having an organic material. For example, as the insulating layer 132, acrylic resin, polyimide resin, epoxy resin, polyamide resin, polyimidoamide resin, siloxane resin, benzocyclobutene resin, phenol resin, and precursors of these resins can be used. Alternatively, a photosensitive resin can be used as the insulating layer 132. The photosensitive resin can be a positive-type material or a negative-type material.

[0124] By using a photosensitive resin as the insulating layer 132, the insulating layer 132 can be manufactured using only exposure and development processes. Therefore, the manufacturing process of the display device 100 can be simplified, and thus the manufacturing cost of the display device 100 can be reduced. Consequently, the display device 100 can be made into a low-cost display device.

[0125] When an organic material is used as the insulating layer 132, the insulating layer 132 may contain oxygen or water. As mentioned above, if oxygen or water penetrates the EL layer 112, the light-emitting element 110 may deteriorate. In the display device 100, the insulating layer 132 is provided in contact with the protective layer 131. For example, the insulating layer 132 is provided so that its sides and bottom surface are in contact with the protective layer 131. This suppresses the penetration of oxygen or water contained in the insulating layer 132 into the EL layer 112, making the display device 100 a highly reliable display device.

[0126] As shown in Figure 2A, the number of protective layers 131 located between the EL layer 112R and the insulating layer 132, the number of protective layers 131 located between the EL layer 112G and the insulating layer 132, and the number of protective layers 131 located between the EL layer 112B and the insulating layer 132 can be different from each other. Figures 2A and 2B show an example in which three protective layers 131 are provided between the EL layer 112R and the insulating layer 132, two protective layers 131 are provided between the EL layer 112G and the insulating layer 132, and one protective layer 131 is provided between the EL layer 112B and the insulating layer 132. Furthermore, Figures 2A and 2B show examples where the number of protective layers 131 provided between the pixel electrode 111R and the insulating layer 132, the number of protective layers 131 provided between the pixel electrode 111G and the insulating layer 132, and the number of protective layers 131 provided between the pixel electrode 111B and the insulating layer 132 are all 3. Note that the number of protective layers 131 is not limited to the examples shown in Figures 2A and 2B, and can be appropriately varied depending on the manufacturing method of the display device 100, as will be described in detail later. Also, the protective layer 131 located between the pixel electrode 111 and the protective layer 131 in contact with the insulating layer 132 may be omitted.

[0127] A protective layer 133 is provided on the insulating layer 132. For example, the protective layer 133 is provided such that it has a region in contact with the upper surface of the insulating layer 132. The protective layer 133 is provided, for example, between the insulating layer 132 and the common layer 114. As described above, the common layer 114 is provided on the EL layer 112R, the EL layer 112G, and the EL layer 112B, and the common electrode 115 is provided on the common layer 114. Therefore, the common layer 114 and the common electrode 115 are provided on the EL layer 112R, the EL layer 112G, the EL layer 112B, and the protective layer 133.

[0128] The protective layer 133 can be provided such that it has an area that overlaps with the upper surface of the protective layer 131, which is provided between the EL layer 112 and the insulating layer 132. In Figures 2A and 2B, the edges of the EL layer 112 and the protective layer 133 coincide, but the edges of the EL layer 112 and the protective layer 133 do not have to coincide. For example, the edge of the protective layer 133 may be located between the edge of the protective layer 131 provided on the surface in contact with the EL layer 112 and the edge of the protective layer 131 provided on the surface in contact with the insulating layer 132.

[0129] The protective layer 133 is preferably a layer with high barrier properties against oxygen and water. This prevents impurities such as oxygen and water contained in the insulating layer 132, which may have an organic insulating material such as resin, from penetrating the common layer 114. Thus, the display device 100 can be made into a highly reliable display device.

[0130] As described above, in the display device 100, the insulating layer 132 is surrounded by protective layers 131 and 133, which have high barrier properties against oxygen and water. This makes the display device 100 a highly reliable display device.

[0131] As the protective layer 133, an inorganic insulating material can be used, for example, a nitride. Specifically, the protective layer 133 may include at least one of silicon nitride, aluminum nitride, or hafnium nitride. Alternatively, an oxide or oxynitride can be used as the protective layer 133, for example, an oxide film or oxynitride film such as silicon oxide, silicon oxynitride, aluminum oxide, aluminum oxynitride, hafnium oxide, and hafnium oxynitride can be used. Furthermore, the protective layer 133 can be formed using, for example, sputtering, CVD, vacuum deposition, pulsed laser deposition (PLD), or atomic layer deposition (ALD).

[0132] A protective layer 121 is provided on the common electrode 115, covering the light-emitting elements 110R, 110G, and 110B. The protective layer 121 has the function of preventing impurities such as water from diffusing to each light-emitting element 110 from above.

[0133] The protective layer 121 can be, for example, a single-layer structure or a multilayer structure including at least an inorganic insulating film. Examples of inorganic insulating films include oxide films or nitride films such as silicon oxide films, silicon oxide nitride films, silicon nitride films, silicon nitride films, aluminum oxide films, aluminum oxide nitride films, and hafnium oxide films. Alternatively, semiconductor materials such as indium gallium oxide or indium gallium zinc oxide may be used as the protective layer 121.

[0134] Furthermore, a laminated film of an inorganic insulating film and an organic insulating film can be used as the protective layer 121. For example, it is preferable to have a configuration in which an organic insulating film is sandwiched between a pair of inorganic insulating films. It is also preferable that the organic insulating film functions as a planarizing film. This makes the upper surface of the organic insulating film flat, thereby improving the coverage of the inorganic insulating film on top of it and enhancing its barrier properties. In addition, since the upper surface of the protective layer 121 is flat, it is preferable because it reduces the influence of uneven shapes caused by the structure below when a structure (e.g., a color filter, electrodes for a touch sensor, or a lens array, etc.) is provided above the protective layer 121.

[0135] Figure 2C1 shows a cross-section corresponding to the dashed line C1-C2 in Figure 1. In the cross-section shown by the dashed line C1-C2, a region 130 is provided where the connecting electrode 111C and the common electrode 115 are electrically connected. In Figure 2C1, an example is shown in which a common layer 114 is provided between the connecting electrode 111C and the common electrode 115, but the region 130 may be configured without a common layer 114. Figure 2C2 shows a cross-section corresponding to the dashed line C1-C2 in Figure 1 when the region 130 does not have a common layer 114. By configuring the region 130 without a common layer 114, the connecting electrode 111C and the common electrode 115 can be in contact, and the contact resistance can be further reduced.

[0136] In region 130, a common electrode 115 is provided on the connecting electrode 111C, and a protective layer 121 is provided covering the common electrode 115. In addition, a protective layer 131 and an insulating layer 132 are provided in a region that does not overlap with the upper surface of the connecting electrode 111C, and a protective layer 133 is provided on the protective layer 131 and on the insulating layer 132. Furthermore, in the example shown in Figure 2C1, a common layer 114 is provided on the connecting electrode 111C, on the protective layer 133, and on the layer 101 containing the transistor. Note that Figures 2C1 and 2C2 show an example in which three protective layers 131 are provided on both sides of the connecting electrode 111C, but the present invention is not limited to this, and as will be described in detail later, it can be appropriately varied depending on, for example, the manufacturing method of the display device 100.

[0137] Figure 2D shows an enlarged view of the area enclosed by the dashed line in Figure 2A. As shown in Figure 2D, the insulating layer 132 can be concave.

[0138] Furthermore, the protective layer 131 can have a two-layer laminated structure, for example, as shown in Figure 2D, it can have a two-layer laminated structure of protective layer 131a and protective layer 131b. In this case, for example, the side surface of the EL layer 112 may have a region in contact with the protective layer 131a. Also, in a protective layer 131 having regions in contact with the side surface and bottom surface of the insulating layer 132, the protective layer 131b has regions in contact with the side surface and bottom surface of the insulating layer 132, and the protective layer 131a has regions in contact with the side surface and bottom surface of the protective layer 131b.

[0139] The protective layer 131a can be a layer formed by processing a film deposited by a highly covering method, for example, and the protective layer 131b can be a layer formed by processing a film deposited by a less covering method, for example. For example, the protective layer 131a can be a layer formed by processing a film deposited by the ALD method, and the protective layer 131b can be a layer formed by processing a film deposited by the sputtering method or the CVD method. This allows the protective layer 131 to have a thicker film while covering any steps. Therefore, the penetration of oxygen and impurities such as water into the EL layer 112 can be effectively suppressed. Consequently, the display device 100 can be made into a highly reliable display device.

[0140] For example, the protective layer 131a can be an inorganic oxide or inorganic nitride, and may include at least one of the following: aluminum oxide, silicon oxide, silicon oxide nitride, silicon oxide nitride, silicon nitride, aluminum oxide nitride, or hafnium oxide. The protective layer 131b can also be an inorganic nitride, and may include at least one of the following: silicon nitride, aluminum nitride, or hafnium nitride.

[0141] The thickness of protective layer 131a is preferably, for example, 1 nm to 60 nm, more preferably 1 nm to 40 nm, and even more preferably 5 nm to 20 nm. The thickness of protective layer 131b is preferably, for example, 60 nm to 300 nm, more preferably 60 nm to 150 nm, and even more preferably 80 nm to 120 nm. It is preferable that protective layer 131a and protective layer 131b be of a film type and thickness that does not contain pinholes.

[0142] Figures 3A and 3B show modified configurations of Figure 2D. The configurations shown in Figures 3A and 3B differ from the configuration shown in Figure 2D, for example, in the shape of the insulating layer 132.

[0143] The insulating layer 132 shown in Figure 3A has a flat upper surface. The insulating layer 132 shown in Figure 3B has a region that overlaps with the upper surface of the EL layer 112. In the configuration shown in Figure 3B, a sacrificial layer 145 is provided between the upper surface of the EL layer 112 and the insulating layer 132. For example, the sacrificial layer 145 is provided between the upper surface of the EL layer 112 and the protective layer 131. Here, the sacrificial layer 145 can be a two-layer laminated structure of sacrificial layer 145a and sacrificial layer 145b. In Figure 3B, the sacrificial layer 145 is shown as sacrificial layer 145R provided between the upper surface of the EL layer 112R and the insulating layer 132, and sacrificial layer 145G provided between the upper surface of the EL layer 112G and the insulating layer 132. Details of the sacrificial layer 145 will be described later.

[0144] In Figure 3B, the edge of the protective layer 133 coincides with the edge of the sacrificial layer 145, but the edge of the protective layer 133 does not have to coincide with the edge of the sacrificial layer 145. For example, the protective layer 133 may have a region that is in contact with the upper surface of the EL layer 112. In other words, the protective layer 133 may be configured to cover the side surface of the sacrificial layer 145.

[0145] [Pixel layout] Next, we will describe a pixel layout different from that shown in Figure 1. There are no particular limitations on the arrangement of subpixels, and various methods can be applied. Examples of subpixel arrangements include stripe arrangements, S-stripe arrangements, matrix arrangements, delta arrangements, Bayer arrangements, and pentile arrangements.

[0146] Furthermore, the top surface shape of the sub-pixel can be, for example, a triangle, a quadrilateral (including rectangles and squares), a pentagon, or other polygons, a polygon with rounded corners, an ellipse, or a circle. Here, the top surface shape of the sub-pixel corresponds to the top surface shape of the light-emitting region of the light-emitting element.

[0147] The pixel 103 shown in Figure 4A has an S-stripe array applied to it. The pixel 103 shown in Figure 4A is composed of three subpixels: subpixel 103a, subpixel 103b, and subpixel 103c. For example, as shown in Figure 5A, subpixel 103a may be a blue subpixel B, subpixel 103b may be a red subpixel R, and subpixel 103c may be a green subpixel G.

[0148] The pixel 103 shown in Figure 4B includes a sub-pixel 103a with a roughly trapezoidal top surface shape with rounded corners, a sub-pixel 103b with a roughly triangular top surface shape with rounded corners, and a sub-pixel 103c with a roughly square, roughly hexagonal, or roughly octagonal top surface shape with rounded corners. Furthermore, sub-pixel 103a has a larger light-emitting area than sub-pixel 103b. Thus, the shape and size of each sub-pixel can be determined independently. For example, the size of a sub-pixel can be reduced to a level that provides a more reliable light-emitting element. For example, as shown in Figure 5B, sub-pixel 103a may be a green sub-pixel G, sub-pixel 103b may be a red sub-pixel R, and sub-pixel 103c may be a blue sub-pixel B.

[0149] A Pentile array is applied to pixels 124a and 124b shown in Figure 4C. Figure 4C shows an example in which pixels 124a having subpixels 103a and 103b, and pixels 124b having subpixels 103b and 103c are arranged alternately. For example, as shown in Figure 5C, subpixel 103a may be a red subpixel R, subpixel 103b may be a green subpixel G, and subpixel 103c may be a blue subpixel B.

[0150] Pixels 124a and 124b, shown in Figures 4D and 4E, utilize a delta array. Pixel 124a has two subpixels (subpixels 103a and 103b) in the top row (1st row) and one subpixel (subpixel 103c) in the bottom row (2nd row). Pixel 124b has one subpixel (subpixel 103c) in the top row (1st row) and two subpixels (subpixels 103a and 103b) in the bottom row (2nd row). For example, as shown in Figure 5D, subpixel 103a may be a red subpixel R, subpixel 103b a green subpixel G, and subpixel 103c a blue subpixel B.

[0151] Figure 4D shows an example where each subpixel has a roughly square top shape with rounded corners, and Figure 4E shows an example where each subpixel has a circular top shape.

[0152] Figure 4F shows an example where the subpixels of each color are arranged in a zigzag pattern. Specifically, in a top view, the upper edges of two subpixels aligned in the column direction (for example, subpixels 103a and 103b, or subpixels 103b and 103c) are offset. For example, as shown in Figure 5E, subpixel 103a may be the red subpixel R, subpixel 103b may be the green subpixel G, and subpixel 103c may be the blue subpixel B.

[0153] In photolithography, the finer the pattern being processed, the more significant the effects of light diffraction become. This compromises the fidelity of transferring the photomask pattern through exposure, making it difficult to process the resist mask into the desired shape. Therefore, even if the photomask pattern is rectangular, patterns with rounded corners are likely to form. Consequently, the top surface shape of subpixels may be a polygon with rounded corners, an ellipse, or a circle.

[0154] Furthermore, in a method for manufacturing a display device according to one aspect of the present invention, the EL layer is processed into an island shape using a resist mask. The resist film formed on the EL layer needs to be cured at a temperature lower than the heat resistance temperature of the EL layer. Therefore, depending on the heat resistance temperature of the EL layer material and the curing temperature of the resist material, the curing of the resist film may be insufficient. A resist film that is not sufficiently cured may take a shape that deviates from the desired shape during processing. As a result, the top surface shape of the EL layer may become a polygon with rounded corners, an ellipse, or a circle. For example, if an attempt is made to form a resist mask with a square top surface, a resist mask with a circular top surface may be formed, resulting in a circular top surface shape for the EL layer.

[0155] Furthermore, in order to achieve the desired shape of the upper surface of the EL layer, a technique (OPC (Optical Proximity Correction) technique) may be used to pre-correct the mask pattern so that the design pattern and the transferred pattern match. Specifically, in the OPC technique, for example, a correction pattern is added to the corners of the shape on the mask pattern.

[0156] [Example of manufacturing method] In the following section, an example of a method for manufacturing a display device according to one aspect of the present invention will be described with reference to the drawings. Here, the display device 100 shown in the above configuration example will be used as an example.

[0157] The thin films (insulating films, semiconductor films, and conductive films, etc.) that constitute the display device can be formed using sputtering, CVD, vacuum deposition, PLD, or ALD methods. CVD methods include plasma-enhanced CVD (PECVD) and thermal CVD. One type of thermal CVD is metal-organic CVD (MOCVD). Furthermore, ALD methods include PEALD and thermal ALD.

[0158] Furthermore, thin films (insulating films, semiconductor films, conductive films, etc.) that constitute the display device can be formed by methods such as spin coating, dip coating, spray coating, inkjet printing, dispensing, screen printing, offset printing, doctor knife method, slit coating, roll coating, curtain coating, or knife coating.

[0159] Furthermore, when processing the thin film that constitutes the display device, for example, photolithography can be used. In addition, the thin film may be processed by nanoimprint lithography, sandblasting, or lift-off lithography. Alternatively, island-shaped thin films may be directly formed by a film deposition method using a shielding mask such as a metal mask.

[0160] There are two main methods of photolithography. One method involves forming a resist mask on the thin film to be processed, then processing the thin film, for example by etching, and removing the resist mask. The other method involves forming a photosensitive thin film, then exposing and developing it to process the thin film into the desired shape.

[0161] In photolithography, the light used for exposure can be, for example, i-line (wavelength 365 nm), g-line (wavelength 436 nm), h-line (wavelength 405 nm), or a mixture thereof. Other light sources such as ultraviolet light, KrF laser light, or ArF laser light can also be used. Exposure may also be performed using immersion lithography. Furthermore, extreme ultraviolet (EUV) light or X-rays may be used as the light source for exposure. An electron beam can also be used instead of light for exposure. Using extreme ultraviolet light, X-rays, or an electron beam is preferable because it allows for extremely fine processing. Note that a photomask is not required when exposure is performed by scanning a beam such as an electron beam.

[0162] For etching thin films, dry etching, wet etching, or sandblasting methods can be used.

[0163] To fabricate the display device 100, first, a layer 101 containing transistors is formed on a substrate (not shown). As mentioned above, the layer 101 containing transistors can be a laminated structure in which, for example, an insulating layer is provided so as to cover the transistors.

[0164] As the substrate, a substrate with sufficient heat resistance to withstand subsequent heat treatment can be used. When using an insulating substrate, glass substrates, quartz substrates, sapphire substrates, ceramic substrates, or organic resin substrates can be used. In addition, semiconductor substrates such as single-crystal semiconductor substrates, polycrystalline semiconductor substrates, compound semiconductor substrates such as silicon-germanium, or SOI substrates made from silicon or silicon carbide can be used.

[0165] Next, a conductive film that will become the pixel electrode 111 is deposited on the layer 101 containing the transistor. Specifically, for example, a conductive film that will become the pixel electrode 111 is deposited on the insulating surface of the layer 101 containing the transistor. Subsequently, a portion of the conductive film is etched away to form the pixel electrode 111R, pixel electrode 111G, pixel electrode 111B, and connecting electrode 111C on the layer 101 containing the transistor (Figure 6A).

[0166] When using a conductive layer that is reflective to visible light as a pixel electrode, it is preferable to use a material (for example, silver or aluminum) that has the highest possible reflectivity across the entire wavelength range of visible light. This not only improves the light extraction efficiency of the light-emitting element but also enhances color reproduction.

[0167] Next, an EL film 112Rf, which will later become the EL layer 112R, is formed on the pixel electrodes 111R, 111G, and 111B, and on the layer 101 containing the transistor. Here, the EL film 112Rf can be formed so as not to overlap with the connecting electrode 111C. For example, by shielding the region containing the connecting electrode 111C with a metal mask and forming the EL film 112Rf, the EL film 112Rf can be formed so as not to overlap with the connecting electrode 111C. In this case, the metal mask does not need to shield the pixel region of the display unit, so it is not necessary to use a high-resolution mask.

[0168] The EL film 112Rf has a film containing at least a luminescent compound. In addition, it may have a structure in which one or more films functioning as a hole injection layer, hole transport layer, hole blocking layer, electron blocking layer, electron transport layer, or electron injection layer are laminated. The EL film 112Rf can be formed by, for example, vapor deposition, sputtering, or inkjet. However, it is not limited to these, and the above-mentioned film formation methods can be used as appropriate.

[0169] Next, a sacrificial film 144Ra is formed on the EL film 112Rf, the connecting electrode 111C, and the layer 101 containing the transistor, and a sacrificial film 144Rb is formed on the sacrificial film 144Ra. In other words, a two-layer stacked sacrificial film is formed on the EL film 112Rf, the connecting electrode 111C, and the layer 101 containing the transistor. Note that the sacrificial film may be a single layer or a stacked structure of three or more layers. In subsequent steps, when forming a sacrificial film, a two-layer stacked sacrificial film is formed, but it may be a single layer or a stacked structure of three or more layers.

[0170] For the formation of the sacrificial films 144Ra and 144Rb, for example, sputtering, CVD, ALD, or vacuum deposition can be used. A formation method that causes minimal damage to the EL layer is preferred, and the sacrificial film 144Ra, which is formed directly on the EL film 112Rf, is preferably formed using the ALD or vacuum deposition method.

[0171] As the sacrificial film 144Ra, a metal film, alloy film, metal oxide film, semiconductor film, or an inorganic film such as an inorganic insulating film can be suitably used.

[0172] Furthermore, an oxide film can be used as the sacrificial film 144Ra. Typically, oxide films or oxynitride films such as silicon oxide, silicon oxynitride, aluminum oxide, aluminum oxynitride, hafnium oxide, and hafnium oxynitride can be used. Alternatively, a nitride film can be used as the sacrificial film 144Ra. Specifically, nitrides such as silicon nitride, aluminum nitride, hafnium nitride, titanium nitride, tantalum nitride, tungsten nitride, gallium nitride, or germanium nitride can be used. Such inorganic insulating materials can be formed using film deposition methods such as sputtering, CVD, or ALD, but the sacrificial film 144Ra formed directly on the EL film 112Rf is preferably formed using the ALD method.

[0173] Furthermore, as the sacrificial film 144Ra, metal materials such as nickel, tungsten, chromium, molybdenum, cobalt, palladium, titanium, aluminum, yttrium, zirconium, and tantalum, or alloy materials containing such metal materials, can be used. In particular, it is preferable to use low-melting-point materials such as aluminum or silver.

[0174] Furthermore, metal oxides such as indium gallium zinc oxide (In-Ga-Zn oxide, also written as IGZO) can be used as the sacrificial film 144Ra. In addition, 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), or indium gallium tin zinc oxide (In-Ga-Sn-Zn oxide) can be used. Alternatively, for example, indium tin oxide containing silicon can be used.

[0175] Furthermore, the above-mentioned method can also be applied when element M (where M is one or more selected from aluminum, silicon, boron, yttrium, copper, vanadium, beryllium, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, and magnesium) is used instead of gallium. In particular, it is preferable that M be one or more selected from gallium, aluminum, and yttrium.

[0176] As the sacrificial film 144Rb, any of the materials listed above that can be used as the sacrificial film 144Ra can be used. For example, one material can be selected as the sacrificial film 144Ra from the materials listed above that can be used as the sacrificial film 144Ra, and another material can be selected as the sacrificial film 144Rb. Alternatively, from the materials listed above that can be used as the sacrificial film 144Ra, one or more materials can be selected for the sacrificial film 144Ra, and one or more materials selected from materials other than those selected for the sacrificial film 144Ra can be used for the sacrificial film 144Rb.

[0177] Specifically, it is preferable to use aluminum oxide formed by the ALD method as the sacrificial film 144Ra and silicon nitride formed by the sputtering method as the sacrificial film 144Rb. In this configuration, it is preferable to set the film deposition temperature during film deposition by the ALD method and the sputtering method to room temperature or higher and 120°C or lower, preferably room temperature or higher and 100°C or lower, as this reduces the effect on the EL film 112Rf. Furthermore, in the case of a laminated structure of sacrificial film 144Ra and sacrificial film 144Rb, it is preferable that the stress of the laminated structure is small. Specifically, it is preferable that the stress of the laminated structure be between -500 MPa and +500 MPa, more preferably between -200 MPa and +200 MPa, as this suppresses process troubles such as film delamination and peeling.

[0178] The sacrificial film 144Ra can be a film with high resistance to etching treatment of each EL film, such as the EL film 112Rf, i.e., a film with a high etching selectivity ratio. Furthermore, it is particularly preferable that the sacrificial film 144Ra be a film that can be removed by a wet etching method that causes little damage to each EL film.

[0179] Furthermore, a material soluble in a chemically stable solvent may be used as the sacrificial film 144Ra. In particular, a material soluble in water or alcohol can be suitably used as the sacrificial film 144Ra. When forming the sacrificial film 144Ra, it is preferable to apply it using a wet deposition method while dissolved in a solvent such as water or alcohol, and then perform a heat treatment to evaporate the solvent. At this time, 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.

[0180] Wet film deposition methods that can be used to form the sacrificial film 144Ra include spin coating, dip coating, spray coating, inkjet printing, dispensing, screen printing, offset printing, doctor knife method, slit coating, roll coating, curtain coating, or knife coating.

[0181] As the sacrificial film 144Ra, organic materials such as polyvinyl alcohol (PVA), polyvinyl butyral, polyvinylpyrrolidone, polyethylene glycol, polyglycerin, pullulan, water-soluble cellulose, or alcohol-soluble polyamide resin can be used.

[0182] For the sacrificial film 144Rb, a film with a high etching selectivity ratio with the sacrificial film 144Ra should be used.

[0183] It is preferable to use an inorganic insulating material such as aluminum oxide, hafnium oxide, and silicon oxide formed by the ALD method as the sacrificial film 144Ra, and a metallic material such as nickel, tungsten, chromium, molybdenum, cobalt, palladium, titanium, aluminum, yttrium, zirconium, and tantalum, or an alloy material containing such a metallic material, formed by the sputtering method, as the sacrificial film 144Rb. In particular, it is preferable to use tungsten formed by the sputtering method as the sacrificial film 144Rb. Alternatively, an indium-containing metal oxide such as indium gallium zinc oxide (In-Ga-Zn oxide, also denoted as IGZO), formed by the sputtering method, may be used as the sacrificial film 144Rb. Furthermore, an inorganic material may be used as the sacrificial film 144Rb. For example, an oxide film or nitride film such as a silicon oxide film, silicon oxide nitride film, silicon nitride film, silicon oxide film, aluminum oxide film, aluminum oxide nitride film, or hafnium oxide film can be used.

[0184] Furthermore, as the sacrificial film 144Rb, an organic film that can be used for the EL film 112Rf may be used, for example. For instance, the same organic film used for the EL film 112Rf can be used as the sacrificial film 144Rb. Using such an organic film is preferable because it allows the same deposition equipment to be used for both the EL film 112Rf and the sacrificial film 144Rb. Moreover, since the sacrificial film 144Rb can be removed simultaneously when etching the EL film 112Rf, the process can be simplified.

[0185] Next, a resist mask 143a is formed on the sacrificial film 144Rb (Figure 6B). The resist mask 143a can be made of a resist material containing a photosensitive resin, such as a positive-type resist material or a negative-type resist material.

[0186] Next, portions of the sacrificial film 144Rb and sacrificial film 144Ra that are not covered by the resist mask 143a are removed by etching to form island-shaped or strip-shaped sacrificial layers 145Rb and 145Ra (Figure 6C). As shown in Figure 6C, the sacrificial layers 145Rb and 145Ra can be formed, for example, on the pixel electrode 111R and on the connecting electrode 111C.

[0187] Here, it is preferable to remove a portion of the sacrificial film 144Rb by etching using the resist mask 143a to form a sacrificial layer 145Rb, then remove the resist mask 143a, and subsequently etch the sacrificial film 144Ra using the sacrificial layer 145Rb as a hard mask. In this case, it is preferable to use etching conditions that have a high selectivity ratio with respect to the sacrificial film 144Ra for etching the sacrificial film 144Rb. For etching to form the hard mask, either a wet etching method or a dry etching method can be used, but by using the dry etching method, pattern reduction can be suppressed.

[0188] The sacrificial films 144Ra and 144Rb, and the resist mask 143a, can be processed by wet etching or dry etching. For example, the sacrificial films 144Ra and 144Rb can be processed by dry etching using a fluorine-containing gas. The resist mask 143a can be removed by dry etching (also known as plasma ashing) using an oxygen-containing gas (also known as oxygen gas).

[0189] When etching the sacrificial film 144Ra using the sacrificial layer 145Rb as a hard mask, the resist mask 143a can be removed while the EL film 112Rf is covered by the sacrificial film 144Ra. For example, if the EL film 112Rf comes into contact with oxygen, it may adversely affect the electrical characteristics of the light-emitting element 110R. Therefore, when removing the resist mask 143a using a method that uses oxygen gas, such as plasma ashing, it is preferable to etch the sacrificial film 144Ra using the sacrificial layer 145Rb as a hard mask.

[0190] Next, a portion of the EL film 112Rf not covered by the sacrificial layer 145Ra is removed by etching to form island-shaped or strip-shaped EL layers 112R (Figure 6D).

[0191] Using a dry etching method with oxygen gas to etch the EL film 112Rf increases the etching rate. Therefore, etching can be performed under low power conditions while maintaining a sufficiently fast etching rate, thereby reducing etching damage. Furthermore, problems such as the adhesion of reaction products to the EL layer 112R during etching can be suppressed.

[0192] On the other hand, etching the EL film 112Rf using a dry etching method with an etching gas that does not contain oxygen as its main component suppresses deterioration of the EL film 112Rf, making the display device 100 a highly reliable display device. Examples of etching gases that do not contain oxygen as its main component include CF4, C4F8, SF6, CHF3, Cl2, H2O, BCl3, and Group 18 elements. For example, helium can be used as a Group 18 element. In addition, a mixed gas of the above gas and an oxygen-free diluent gas can be used as the etching gas. Note that etching of the EL film 112Rf is not limited to the above, and may be carried out by a dry etching method using other gases or by a wet etching method.

[0193] When the EL film 112Rf is etched to form the EL layer 112R, if impurities are attached to the side surface of the EL layer 112R, these impurities may penetrate into the interior of the EL layer 112R in subsequent processes. This may reduce the reliability of the display device 100. Therefore, it is preferable to remove impurities attached to the surface of the EL layer 112R after its formation to improve the reliability of the display device 100.

[0194] Impurities adhering to the surface of the EL layer 112R can be removed, for example, by irradiating the surface of the EL layer 112R with an inert gas. Immediately after the formation of the EL layer 112R, the surface of the EL layer 112R is exposed. Specifically, the side surfaces of the EL layer 112R are exposed. Therefore, after the formation of the EL layer 112R, if the substrate on which the EL layer 112R is formed is placed in an inert gas atmosphere, impurities adhering to the EL layer 112R can be removed. As the inert gas, one or more selected from, for example, Group 18 elements (typically helium, neon, argon, xenon, and krypton, etc.) and nitrogen can be used.

[0195] Next, a protective film 131Rf, which will later become the protective layer 131R, is formed to cover the upper surface of the transistor-containing layer 101, the upper and side surfaces of the pixel electrode 111R, pixel electrode 111G, and pixel electrode 111B, the side surface of the EL layer 112R, the side surface of the sacrificial layer 145Ra, and the side and upper surface of the sacrificial layer 145Rb (Figure 7A1).

[0196] Figure 7A2 shows an enlarged view of the area enclosed by the dashed line in Figure 7A1. As shown in Figure 7A2, the protective film 131Rf can be a two-layer laminated structure consisting of a protective film 131Raf, which later becomes the protective layer 131Ra, and a protective film 131Rbf, which later becomes the protective layer 131Rb.

[0197] It is preferable that the protective film 131Raf is formed by a method with high coverage, for example, and the protective film 131Rbf is formed by a method with low coverage, for example. For example, the protective film 131Raf can be formed by the ALD method, and the protective film 131Rbf can be formed by the sputtering method or the CVD method. This allows the protective film 131Rf to be thickened while covering the steps. Therefore, the penetration of impurities such as oxygen and water into the EL layer 112R can be effectively suppressed. Thus, the display device 100 can be made into a highly reliable display device.

[0198] An inorganic insulating material can be used as the protective film 131Rf. For example, an inorganic oxide or inorganic nitride can be used as the protective film 131Raf, and may include at least one of the following: aluminum oxide, silicon oxide, silicon oxide nitride, silicon oxide nitride, silicon nitride, aluminum oxide nitride, or hafnium oxide. Also, an inorganic nitride can be used as the protective film 131Rbf, and may include at least one of the following: silicon nitride, aluminum nitride, or hafnium nitride.

[0199] The protective film 131Raf is preferably deposited with a thickness of, for example, 1 nm to 60 nm, more preferably 1 nm to 40 nm, and even more preferably 5 nm to 20 nm. The protective film 131Rbf is preferably deposited with a thickness of, for example, 60 nm to 300 nm, more preferably 60 nm to 150 nm, and even more preferably 80 nm to 120 nm. It is preferable that the protective film 131Raf and protective film 131Rbf are pinhole-free films and have a suitable thickness.

[0200] Here, if the EL layer 112R comes into contact with air, oxygen and impurities such as water contained in the air may penetrate into the interior of the EL layer 112R. After the formation of the EL layer 112R, the surface of the EL layer 112R, specifically the side surface of the EL layer 112R, is exposed until the protective film 131Rf is formed. Therefore, it is preferable to perform the processes from etching the EL film 112Rf to forming the protective film 131Rf in the same apparatus. This makes it possible to form the protective film 131Rf that covers the EL layer 112R without exposing the EL layer 112R to air after etching the EL film 112Rf. Thus, it is possible to suppress the penetration of impurities contained in the air into the interior of the EL layer 112R, and to make the display device 100 a highly reliable display device. Furthermore, performing other processes in the same apparatus is preferable because it is possible to suppress the exposure of the components of the display device 100 to air during the manufacturing process of the display device 100, and to increase the throughput in the manufacturing of the display device 100.

[0201] Next, the protective film 131Rf is etched to form the protective layer 131R (Figure 7B1). The protective layer 131R is formed to have a region that overlaps with the side surface of the EL layer 112R. Furthermore, the protective layer 131R is formed to have a region that overlaps with the side surface of the pixel electrode 111R, the side surface of the pixel electrode 111G, the side surface of the pixel electrode 111B, the side surface of the sacrificial layer 145Ra, and the side surface of the sacrificial layer 145Rb. However, if the thickness of the protective film 131Rf is thin, the protective layer 131R may not be formed in the region that overlaps with the side surface of the pixel electrode 111R, the side surface of the pixel electrode 111G, the side surface of the pixel electrode 111B, the side surface of the sacrificial layer 145Ra, or the side surface of the sacrificial layer 145Rb.

[0202] By forming the protective layer 131R such that it overlaps with the side surface of the EL layer 112R, it is possible to suppress the intrusion of impurities such as oxygen and water into the interior from the side surface of the EL layer 112R in subsequent processes. Therefore, the display device 100 can be made into a highly reliable display device.

[0203] Etching the protective film 131Rf by anisotropic etching is preferable because it allows for the suitable formation of the protective layer 131 without the need for patterning using, for example, photolithography. For example, forming the protective layer 131 without patterning using photolithography simplifies the manufacturing process of the display device 100, thereby reducing the manufacturing cost of the display device 100. Therefore, the display device 100 can be made into a low-cost display device. As mentioned above, dry etching is an example of anisotropic etching. When etching the protective film 131Rf by dry etching, for example, the protective film 131Rf can be etched using an etching gas that can be used when etching the sacrificial film 144Ra or the sacrificial film 144Rb.

[0204] Figure 7B2 shows an enlarged view of the area enclosed by the dashed line in Figure 7B1. As shown in Figure 7B2, the protective layer 131R can be a two-layer laminated structure consisting of protective layer 131Ra and protective layer 131Rb.

[0205] Incidentally, in the process shown in Figures 6C to 6D, etching the EL film 112Rf using an oxygen-containing gas may change the surface state of the pixel electrodes 111G and 111B. For example, the surfaces of the pixel electrodes 111G and 111B may become hydrophilic. For example, if the upper surface of the pixel electrodes 111G and 111B is a layer containing indium tin oxide, etching the EL film 112Rf using an oxygen-containing gas may cause the indium tin oxide-containing layer to become hydrophilic. Here, the EL film formed to have a region in contact with the pixel electrode 111G in a later process, and the EL film formed to have a region in contact with the pixel electrode 111B, are, for example, hydrophobic. The adhesion between a hydrophilic surface and a hydrophobic surface is lower than the adhesion between hydrophilic surfaces and between hydrophobic surfaces. Therefore, if the surfaces of the pixel electrodes 111G and 111B are hydrophilic, the adhesion to the EL film formed in a later process may be reduced. Therefore, in subsequent processes, the EL film may peel off at the interface with the pixel electrode 111G or the interface with the pixel electrode 111B. In addition, if the EL film 112Rf is etched using an oxygen-containing gas, in addition to the above-mentioned changes in surface condition, the work function of the surfaces of the pixel electrode 111G and the pixel electrode 111B may change.

[0206] Therefore, by performing a hydrophobic treatment on the surface of the pixel electrode 111G and the surface of the pixel electrode 111B, peeling of the EL film formed in a later process can be suppressed. Thus, the display device 100 can be made into a highly reliable display device. In addition, the yield in the manufacture of the display device 100 can be increased, making the display device 100 a low-cost display device. The hydrophobic treatment is preferably performed after the formation of the protective layer 131R.

[0207] Hydrophobic treatment can be performed, for example, by fluorine modification of the pixel electrodes 111G and 111B. Fluorine modification can be performed, for example, by treatment with a fluorine-containing gas, heat treatment, or plasma treatment in a fluorine-containing gas atmosphere. As the fluorine-containing gas, for example, fluorine gas can be used, or for example, fluorocarbon gas can be used. As the fluorocarbon gas, for example, lower fluorinated carbon gases such as carbon tetrafluoride (CF4) gas, C4F6 gas, C2F6 gas, C4F8 gas, or C5F8 can be used. In addition, as the fluorine-containing gas, for example, SF6 gas, NF3 gas, or CHF3 gas can be used. Furthermore, helium gas, argon gas, or hydrogen gas can be added to these gases as appropriate.

[0208] Furthermore, the surfaces of the pixel electrodes 111G and 111B can be made hydrophobic by performing plasma treatment in a gas atmosphere containing a group 18 element such as argon, followed by treatment with a silylation agent. Hexamethyldisilazane (HMDS) or trimethylsilylimidazole (TMSI) can be used as the silylation agent. In addition, the surfaces of the pixel electrodes 111G and 111B can also be made hydrophobic by performing plasma treatment in a gas atmosphere containing a group 18 element such as argon, followed by treatment with a silane coupling agent.

[0209] By performing plasma treatment on the surfaces of pixel electrodes 111G and 111B in a gas atmosphere containing a group 18 element such as argon, damage can be inflicted on the surfaces of pixel electrodes 111G and 111B. This makes it easier for methyl groups contained in silylation agents such as HMDS to bond to the surfaces of pixel electrodes 111G and 111B. It also facilitates silane coupling by silane coupling agents. As a result, by performing plasma treatment on the surfaces of pixel electrodes 111G and 111B in a gas atmosphere containing a group 18 element such as argon, followed by treatment with a silylation agent or a silane coupling agent, the surfaces of pixel electrodes 111G and 111B can be made hydrophobic.

[0210] Treatment using a silylation agent or silane coupling agent can be carried out by applying the silylation agent or silane coupling agent using, for example, a spin coating method or a dip method. Alternatively, treatment using a silylation agent or silane coupling agent can be carried out by forming a film containing a silylation agent or a film containing a silane coupling agent on the pixel electrode 111G and the pixel electrode 111B using, for example, a vapor phase method. In the vapor phase method, first, the silylation agent or silane coupling agent is introduced into the atmosphere by volatilizing the material containing the silylation agent or the material containing the silane coupling agent. Subsequently, the substrate on which the pixel electrode 111G and the pixel electrode 111B are formed is placed in the atmosphere. This allows a film containing a silylation agent or silane coupling agent to be formed on the pixel electrode 111G and the pixel electrode 111B, and the surfaces of the pixel electrode 111G and the pixel electrode 111B can be made hydrophobic.

[0211] Next, an EL film 112Gf, which will later become the EL layer 112G, is formed on the sacrificial layer 145Rb, the protective layer 131R, the pixel electrode 111G, the pixel electrode 111B, and the layer 101 containing the transistor. By forming the EL film 112Gf after forming the sacrificial layer 145R and the protective layer 131R, it is possible to prevent the EL film 112Gf from coming into contact with the EL layer 112R. For example, the description of the formation of the EL film 112Gf can be found in the description of the formation of the EL film 112Rf.

[0212] Next, a sacrificial film 144Ga is formed on the EL film 112Gf, on the sacrificial layer 145Rb, and on the layer 101 containing the transistor, and a sacrificial film 144Gb is formed on the sacrificial film 144Ga. Subsequently, a resist mask 143b is formed on the sacrificial film 144Gb (Figure 8A). For details on the formation of the sacrificial film 144Ga, sacrificial film 144Gb, and resist mask 143b, refer to the descriptions of the formation of the sacrificial film 144Ra, sacrificial film 144Rb, and resist mask 143a, respectively.

[0213] Next, portions of the sacrificial layers 144Gb and 144Ga that are not covered by the resist mask 143b are removed by etching to form island-shaped or strip-shaped sacrificial layers 145Gb and 145Ga. The resist mask 143b is then removed (Figure 8B). Here, the sacrificial layers 145Gb and 145Ga can be formed on the pixel electrode 111G. For details on the formation of the sacrificial layers 145Gb and 145Ga, and the removal of the resist mask 143b, refer to the descriptions for the formation of the sacrificial layers 145Rb and 145Ra, and the removal of the resist mask 143a.

[0214] Next, a portion of the EL film 112Gf not covered by the sacrificial layer 145Ga is removed by etching to form island-shaped or strip-shaped EL layers 112G (Figure 8C). For example, the description of the formation of EL layer 112R can be used to refer to the description of the formation of EL layer 112R. Also, similar to EL layer 112R, it is preferable to remove impurities adhering to the surface of EL layer 112G. For example, after the formation of EL layer 112G, placing the substrate on which the EL layer 112G is formed under an inert gas atmosphere can remove impurities adhering to EL layer 112G.

[0215] Next, a protective film 131Gf, which will later become the protective layer 131G, is formed to cover the upper surface of the transistor-containing layer 101, the upper surface of the pixel electrode 111B, the side surface of the EL layer 112G, the side surface of the protective layer 131R, the upper surface of the sacrificial layer 145Rb, the side surface of the sacrificial layer 145Ga, and the side surface and upper surface of the sacrificial layer 145Gb (Figure 9A1). For example, the formation of the protective film 131Gf can be described in the description of the formation of the protective film 131Rf. Here, it is preferable to perform the processes from etching the EL film 112Gf to forming the protective film 131Gf in the same apparatus, because this allows the protective film 131Gf covering the EL layer 112G to be formed without exposing the EL layer 112G to air.

[0216] Figure 9A2 shows an enlarged view of the area enclosed by the dashed line in Figure 9A1. As shown in Figure 9A2, the protective film 131Gf can be a two-layer laminated structure consisting of a protective film 131Gaf, which later becomes the protective layer 131Ga, and a protective film 131Gbf, which later becomes the protective layer 131Gb. For details on the protective film 131Gaf and the protective film 131Gbf, please refer to the descriptions for the protective film 131Raf and the protective film 131Rbf, respectively.

[0217] Next, the protective layer 131G is formed by etching the protective film 131Gf (Figure 9B1). The protective layer 131G is formed to have a region that overlaps with the side surface of the EL layer 112G. Furthermore, the protective layer 131G is formed to have a region that overlaps with the side surface of the protective layer 131R, the side surface of the sacrificial layer 145Ga, and the side surface of the sacrificial layer 145Gb. Note that if the thickness of the protective film 131Gf is thin, the protective layer 131G may not be formed in the region that overlaps with the side surface of the protective layer 131R, the side surface of the sacrificial layer 145Ga, or the side surface of the sacrificial layer 145Gb. For example, the description of the formation of the protective layer 131R can be used to refer to the description of the formation of the protective layer 131R.

[0218] Figure 9B2 shows an enlarged view of the area enclosed by the dashed line in Figure 9B1. As shown in Figure 9B2, the protective layer 131G can be a two-layer laminated structure consisting of protective layer 131Ga and protective layer 131Gb. For details on protective layer 131Ga and protective layer 131Gb, refer to the descriptions for protective layer 131Ra and protective layer 131Rb, respectively.

[0219] Next, an EL film 112Bf, which will later become the EL layer 112B, is formed on the sacrificial layer 145Rb, the sacrificial layer 145Gb, the protective layer 131R, the protective layer 131G, the pixel electrode 111B, and the layer 101 containing the transistor. By forming the EL film 112Bf after forming the sacrificial layer 145G and the protective layer 131G, it is possible to prevent the EL film 112Bf from coming into contact with the EL layer 112G. For example, the description of the formation of the EL film 112Rf can be used to describe the formation of the EL film 112Bf.

[0220] Next, a sacrificial film 144Ba is formed on the EL film 112Bf, on the sacrificial layer 145Rb, and on the transistor-containing layer 101, and a sacrificial film 144Bb is formed on the sacrificial film 144Ba. Subsequently, a resist mask 143c is formed on the sacrificial film 144Bb (Figure 10A). For details on the formation of the sacrificial film 144Ba, sacrificial film 144Bb, and resist mask 143c, refer to the descriptions of the formation of the sacrificial film 144Ra, sacrificial film 144Rb, and resist mask 143a, respectively.

[0221] Next, portions of the sacrificial layers 144Bb and 144Ba that are not covered by the resist mask 143c are removed by etching to form island-shaped or strip-shaped sacrificial layers 145Bb and 145Ba. The resist mask 143c is then removed (Figure 10B). Here, the sacrificial layers 145Bb and 145Ba can be formed on the pixel electrode 111B. For details on the formation of the sacrificial layers 145Bb and 145Ba, and the removal of the resist mask 143c, refer to the descriptions for the formation of the sacrificial layers 145Rb and 145Ra, and the removal of the resist mask 143a.

[0222] Next, a portion of the EL film 112Bf not covered by the sacrificial layer 145Ba is removed by etching to form island-shaped or strip-shaped EL layers 112B (Figure 10C). For example, the description of the formation of EL layer 112R can be used to describe the formation of EL layer 112B. In addition, it is preferable to remove impurities adhering to the surface of EL layer 112B, similar to EL layer 112R and EL layer 112G. For example, after the formation of EL layer 112B, placing the substrate on which the EL layer 112B is formed under an inert gas atmosphere can remove impurities adhering to EL layer 112B.

[0223] Next, a protective film 131Bf, which will later become the protective layer 131B, is formed to cover the upper surface of the transistor-containing layer 101, the side surfaces of the EL layer 112B, the side surfaces of the protective layer 131G, the upper surface of the sacrificial layer 145Rb, the upper surface of the sacrificial layer 145Gb, the side surfaces of the sacrificial layer 145Ba, and the side and upper surfaces of the sacrificial layer 145Bb (Figure 11A). For example, the formation of the protective film 131Bf can be described in the description of the formation of the protective film 131Rf. Here, it is preferable to perform the processes from etching the EL film 112Bf to forming the protective film 131Bf in the same apparatus, because this allows the protective film 131Bf covering the EL layer 112B to be formed without exposing the EL layer 112B to air.

[0224] Figure 11B shows an enlarged view of region 160a shown in Figure 11A, and Figure 11C shows an enlarged view of region 160b shown in Figure 11A. Region 160a includes the region between EL layer 112R and EL layer 112G, and region 160b includes the region between EL layer 112G and EL layer 112B. As shown in Figures 11B and 11C, the protective film 131Bf can be a two-layer laminated structure consisting of a protective film 131Baf, which later becomes protective layer 131Ba, and a protective film 131Bbf, which later becomes protective layer 131Bb. For details on protective film 131Baf and protective film 131Bbf, refer to the descriptions for protective film 131Raf and protective film 131Rbf, respectively.

[0225] Next, an insulating film 132f, which will later become the insulating layer 132, is formed on the protective film 131Bf (Figure 12A). For example, the insulating film 132f is formed so as to be in contact with the protective film 131Bf, specifically the protective film 131Bbf. It is preferable to use an insulating film containing an organic material as the insulating film 132f, and it is preferable to use a resin as the organic material. Alternatively, a photosensitive resin can be used as the insulating film 132f. The photosensitive resin can be a positive-type material or a negative-type material.

[0226] When a photosensitive resin is used as the insulating film 132f, the insulating film 132f can be formed using methods such as spin coating, spraying, screen printing, or painting.

[0227] As shown in Figure 12A, the insulating film 132f may have smooth irregularities that reflect the unevenness of the surface to which it is formed. Furthermore, the insulating film 132f may be flattened.

[0228] Next, an insulating layer 132 is formed (Figure 12B1). By using a photosensitive resin as the insulating film 132f, the insulating layer 132 can be formed without providing an etching mask such as a resist mask or a hard mask. Furthermore, since the photosensitive resin can be processed only by exposure and development steps, the insulating layer 132 can be formed without using, for example, a dry etching method. Thus, the process can be simplified. In addition, damage to the EL layer 112 due to etching of the insulating film 132f can be reduced. Furthermore, a portion of the upper part of the insulating layer 132 may be etched to adjust the surface height.

[0229] Alternatively, an insulating layer 132 may be formed by etching the upper surface of the insulating film 132f substantially uniformly. This process of uniform etching and planarization is also called etch-back.

[0230] In forming the insulating layer 132, the exposure and development process and the etch-back process may be used in combination.

[0231] Figure 12B2 shows an enlarged view of the area enclosed by the dashed line in Figure 12B1. As shown in Figure 12B2, the insulating layer 132 can be concave. Here, the height of the upper end of the insulating layer 132 can be, for example, less than or equal to the height of the upper surface of the protective film 131Bbf.

[0232] Figures 13A and 13B show modified configurations of Figure 12B2. The configurations shown in Figures 13A and 13B differ from those shown in Figure 12B2, for example, in the shape of the insulating layer 132.

[0233] The insulating layer 132 shown in Figure 13A has a flat top surface. In the example shown in Figure 13A, the height of the upper end of the insulating layer 132 is equal to the height of the top surface of the protective film 131Bbf.

[0234] The insulating layer 132 shown in Figure 13B has a region that overlaps with the upper surface of the EL layer 112 via the protective film 131Bf, sacrificial layer 145b, and sacrificial layer 145a. By further processing the insulating layer 132 from the state shown in Figure 13B, the insulating layer 132 can be made into the shape shown in Figure 12B2 or Figure 13A.

[0235] Next, the protective film 131Bf is etched to form the protective layer 131B (Figure 14A). The protective layer 131B is formed to have a region that overlaps with the side surface of the EL layer 112B. The protective layer 131B is also formed to have a region that contacts the side surface of the insulating layer 132 and a region that contacts the bottom surface of the insulating layer 132. For example, the formation of the protective layer 131B can be described in the description of the formation of the protective layer 131R.

[0236] Next, sacrificial layers 145Rb, 145Gb, and 145Bb are removed, for example, by etching (Figure 14B1). For etching sacrificial layer 145b, it is preferable to use conditions that result in a high selectivity ratio with sacrificial layer 145a. Note that removal of sacrificial layer 145b is optional.

[0237] Figure 14B2 shows an enlarged view of the region enclosed by the dashed line in Figure 14B1. Figure 14B2 shows an example in which a portion of the protective layer 131 is removed by the removal of the sacrificial layer 145b, and the uppermost surface of the protective layer 131 having a region in contact with the side surface of the EL layer 112 coincides with the upper surface of the sacrificial layer 145a. However, the present invention is not limited to this. For example, the uppermost surface of the protective layer 131 having a region in contact with the side surface of the EL layer 112 may be higher than the upper surface of the sacrificial layer 145a.

[0238] Next, a protective film 133f, which will later become the protective layer 133, is formed to cover the upper surface of the insulating layer 132 and the upper surfaces of the sacrificial layer 145Ra, sacrificial layer 145Ga, and sacrificial layer 145Ba (Figure 15A). The protective film 133f can be formed using, for example, sputtering, CVD, vacuum deposition, PLD, or ALD.

[0239] An inorganic insulating material can be used as the protective film 133f, for example, a nitride can be used. Specifically, the protective film 133f may include at least one of silicon nitride, aluminum nitride, or hafnium nitride. Alternatively, an oxide or oxynitride can be used as the protective film 133f, for example, an oxide film or oxynitride film such as silicon oxide, silicon oxynitride, aluminum oxide, aluminum oxynitride, hafnium oxide, and hafnium oxynitride can be used.

[0240] Next, the protective film 133f is processed to form the protective layer 133 (Figure 15B1). The protective film 133f can be processed, for example, using photolithography. Specifically, first, a resist mask is formed on the protective film 133f. Next, the portion of the protective film 133f not covered by the resist mask is removed by etching. In this way, the protective layer 133 can be formed.

[0241] Figure 15B2 shows an enlarged view of the area enclosed by the dashed line in Figure 15B1. In Figure 15B2, the edge of the protective layer 133 coincides with the edge of the sacrificial layer 145a, but the edge of the protective layer 133 does not have to coincide with the edge of the sacrificial layer 145a. For example, the protective layer 133 may have an area that overlaps with the sacrificial layer 145a. Also, the edge of the protective layer 133 may be located between the edge of the sacrificial layer 145a and the edge of the insulating layer 132.

[0242] Next, the sacrificial layers 145Ra, 145Ga, and 145Ba are removed, for example, by etching (Figure 16A). It is preferable to remove the sacrificial layers 145Ra, 145Ga, and 145Ba in a way that causes as little damage as possible to the EL layer 112, and for example, a wet etching method is preferred. Note that when removing the sacrificial layers 145Ra, 145Ga, and 145Ba, a portion of the upper part of the protective layer 133 and a portion of the upper part of the protective layer 131 may be etched.

[0243] Next, a vacuum bake treatment is performed to remove water and other substances adsorbed on the surfaces of EL layer 112R, EL layer 112G, and EL layer 112B. The vacuum bake is preferably performed within a temperature range that does not alter the organic compounds contained in EL layer 112R, EL layer 112G, and EL layer 112B, for example, between 70°C and 120°C, more preferably between 80°C and 100°C. However, if there is little water or other substances adsorbed on the surfaces of EL layer 112R, EL layer 112G, and EL layer 112B, for example, and the impact on the reliability of the display device 100 is minimal, the vacuum bake treatment may not be necessary.

[0244] Next, a common layer 114 is formed on the EL layer 112, the protective layer 133, and the layer 101 containing the transistor. As mentioned above, the common layer 114 has at least one of the following: a hole injection layer, a hole transport layer, a hole blocking layer, an electron blocking layer, an electron transport layer, or an electron injection layer, for example, an electron injection layer or a hole injection layer. The common layer 114 can be formed by, for example, a vapor deposition method, a sputtering method, or an inkjet method. If the common layer 114 is not provided on the connecting electrode 111C, a metal mask that shields the connecting electrode 111C can be used when forming the common layer 114. In this case, the metal mask does not need to shield the pixel area of ​​the display unit, so there is no need to use a high-resolution mask.

[0245] Next, a common electrode 115 is formed on the common layer 114. The common electrode 115 can be formed by, for example, sputtering or vacuum deposition. Through the above steps, the light-emitting element 110R, light-emitting element 110G, and light-emitting element 110B can be manufactured.

[0246] Next, a protective layer 121 is formed on the common electrode 115 (Figure 16B). When an inorganic insulating film is used as the protective layer 121, it is preferable to form the protective layer 121 using, for example, a sputtering method, a CVD method, or an ALD method. When an organic insulating film is used as the protective layer 121, it is preferable to form the protective layer 121 using, for example, an inkjet method, because a uniform film can be formed in the desired area.

[0247] By the above steps, the display device 100 can be manufactured.

[0248] As described above, in the method for manufacturing a display device according to one aspect of the present invention, a shadow mask such as a metal mask is not used, and for example, an EL layer is separately formed using a photolithography method and an etching method. Thereby, the pattern of the EL layer can be made into a fine pattern. Therefore, a display device with high definition and a high aperture ratio can be manufactured by the method for manufacturing a display device according to one aspect of the present invention. In addition, a display device with high resolution and a large-sized display device can be manufactured. Furthermore, since the EL layer can be separately formed, a display device that is extremely vivid, has high contrast, and has high display quality can be manufactured.

[0249] [Configuration Example_2] In the configurations shown in FIGS. 2A, 2B, and 2D, etc., the side surface of the EL layer 112R is located inside the side surface of the pixel electrode 111R, the side surface of the EL layer 112G is located inside the side surface of the pixel electrode 111G, and the side surface of the EL layer 112B is located inside the side surface of the pixel electrode 111B. However, the configuration of the display device according to one aspect of the present invention is not limited to this. FIG. 17A is a cross-sectional view corresponding to the dashed-dotted line A1 - A2 in FIG. 1, FIG. 17B is a cross-sectional view corresponding to the dashed-dotted line B1 - B2 in FIG. 1, FIG. 17C is a cross-sectional view corresponding to the dashed-dotted line C1 - C2 in FIG. 1, and FIG. 17D is an enlarged view of the region surrounded by the dashed-dotted line in FIG. 17A. FIGS. 17A, 17B, 17C, and 17D are modified examples of the configurations shown in FIGS. 2A, 2B, 2C1, and 2D, and are different in that the side surface of the pixel electrode 111R coincides with the side surface of the EL layer 112R, the side surface of the pixel electrode 111G coincides with the side surface of the EL layer 112G, and the side surface of the pixel electrode 111B coincides with the side surface of the EL layer 112B.

[0250] Figure 18A is a cross-sectional view corresponding to the dashed line A1-A2 in Figure 1, Figure 18B is a cross-sectional view corresponding to the dashed line B1-B2 in Figure 1, Figure 18C is a cross-sectional view corresponding to the dashed line C1-C2 in Figure 1, and Figure 18D is an enlarged view of the area enclosed by the dashed line in Figure 18A. Figures 18A, 18B, 18C, and 18D are modified examples of the configurations shown in Figures 2A, 2B, 2C1, and 2D, differing in that the side surface of the EL layer 112R is located outside the side surface of the pixel electrode 111R, the side surface of the EL layer 112G is located outside the side surface of the pixel electrode 111G, and the side surface of the EL layer 112B is located outside the side surface of the pixel electrode 111B. In the configurations shown in Figures 18A and 18B, the EL layer 112 is provided so as to cover the side surface of the pixel electrode 111.

[0251] Figure 19A is a cross-sectional view corresponding to the dashed line A1-A2 in Figure 1, Figure 19B is a cross-sectional view corresponding to the dashed line B1-B2 in Figure 1, Figure 19C is a cross-sectional view corresponding to the dashed line C1-C2 in Figure 1, and Figure 19D is an enlarged view of the area enclosed by the dashed line in Figure 19A. Figures 19A, 19B, 19C, and 19D are modified examples of the configurations shown in Figures 2A, 2B, 2C1, and 2D, differing in that the protective layer 133 is not provided. In the configurations shown in Figures 19A to 19D, for example, a configuration can be made in which the insulating layer 132 and the common layer 114 are in contact.

[0252] By omitting the protective layer 133, the process of forming the protective layer 133 is eliminated, thus simplifying the manufacturing process of the display device 100. Therefore, the manufacturing cost of the display device 100 can be reduced, making the display device 100 a low-cost display device.

[0253] Figure 20A is a cross-sectional view corresponding to the dashed line A1-A2 in Figure 1. Figure 20B is a cross-sectional view corresponding to the dashed line B1-B2 in Figure 1. Figure 20C is a cross-sectional view corresponding to the dashed line C1-C2 in Figure 1. Figure 20D is an enlarged view of the area enclosed by the dashed line in Figure 20A. Figures 20A, 20B, 20C, and 20D are modified examples of the configurations shown in Figures 2A, 2B, 2C1, and 2D, differing in that the protective layer 133 has an overlapping area with the EL layer 112.

[0254] In the configurations shown in Figures 20A to 20D, a sacrificial layer 145Ra remains between the upper surface of EL layer 112R and the protective layer 133, a sacrificial layer 145Ga remains between the upper surface of EL layer 112G and the protective layer 133, and a sacrificial layer 145Ba remains between the upper surface of EL layer 112B and the protective layer 133. Depending on the manufacturing process of the display device 100, a sacrificial layer 145Rb may remain between the sacrificial layer 145Ra and the protective layer 133, a sacrificial layer 145Gb may remain between the sacrificial layer 145Ga and the protective layer 133, and a sacrificial layer 145Bb may remain between the sacrificial layer 145Ba and the protective layer 133. In addition, there may be regions where sacrificial layers 145Ra, 145Ga, and 145Ba do not remain, and EL layers 112R, 112G, and 112B are in contact with the protective layer 133. Furthermore, in the configurations shown in Figures 20A to 20D, the edges of the protective layer 133 coincide with the edges of the sacrificial layer 145a, but the edges of the protective layer 133 do not necessarily have to coincide with the edges of the sacrificial layer 145a. For example, the protective layer 133 may have a region that is in contact with the upper surface of the EL layer 112. In other words, the protective layer 133 may be configured to cover the side surface of the sacrificial layer 145a.

[0255] The configuration examples illustrated in this embodiment, and the corresponding drawings, etc., can be appropriately combined with other configuration examples or drawings, etc., at least in part.

[0256] (Embodiment 2) This embodiment describes an example of the configuration of a display device according to one aspect of the present invention.

[0257] The display device of this embodiment can be a high-resolution display device or a large-screen display device. Therefore, the display device of this embodiment can be used in electronic devices with relatively large screens, such as television sets, desktop or notebook personal computers, computer monitors, digital signage, and large game machines such as pachinko machines, as well as in the display units of digital cameras, digital video cameras, digital photo frames, mobile phones, portable game consoles, smartphones, smartwatches, tablet terminals, personal information terminals, and audio playback devices.

[0258] [Display Module_1] Figure 21 shows a perspective view of the display device 100A, and Figure 22A shows a cross-sectional view of the display device 100A.

[0259] The display device 100A has a configuration in which substrate 452 and substrate 451 are bonded together. In Figure 21, substrate 452 is indicated by a dashed line.

[0260] The display device 100A includes a display unit 462, a circuit 464, and wiring 465, etc. Figure 21 shows an example in which IC 473 and FPC 472 are mounted on the display device 100A. Therefore, the configuration shown in Figure 21 can also be described as a display module having the display device 100A, an IC (integrated circuit), and an FPC. Note that the display device included in this display module is not limited to the display device 100A, but may also be the display device 100B described later.

[0261] For example, a scan line drive circuit can be used as circuit 464.

[0262] Wiring 465 has the function of supplying signals and power to the display unit 462 and the circuit 464. These signals and power are input to wiring 465 from an external source via FPC 472 or from IC 473.

[0263] Figure 21 shows an example in which IC 473 is mounted on substrate 451 using the COG method or COF (Chip On Film) method. IC 473 can be an IC having, for example, a scan line drive circuit or a signal line drive circuit. Note that the display module having the display device 100A may be configured without an IC. Alternatively, the IC may be mounted on an FPC, for example, using the COF method.

[0264] [Display device 100A] Figure 22A shows an example of a cross-section obtained by cutting a portion of the display device 100A, including the FPC 472, a portion of the circuit 464, a portion of the display unit 462, and a portion of the end portion.

[0265] The display device 100A shown in Figure 22A has a transistor 201, a transistor 205, a light-emitting element 110R that emits red light, a light-emitting element 110G that emits green light, and a light-emitting element 110B that emits blue light, etc., between substrates 451 and 452. Here, in the display device 100A, the laminated structure from substrate 451 to insulating layer 214 corresponds to the layer 101 containing the transistors in Embodiment 1.

[0266] The light-emitting elements 110R, 110G, and 110B can be the light-emitting elements exemplified in Embodiment 1.

[0267] Here, if the pixels of the display device have three types of subpixels that have light-emitting elements that emit different colors from each other, examples of such three subpixels include subpixels of three colors R, G, and B, and subpixels of three colors: yellow (Y), cyan (C), and magenta (M). If there are four such subpixels, examples of such four subpixels include subpixels of four colors: R, G, B, and white (W), and subpixels of four colors: R, G, B, and Y.

[0268] The protective layer 121 and the substrate 452 are adhered via an adhesive layer 442. For encapsulating the light-emitting element, a solid encapsulation structure, a hollow encapsulation structure, or the like can be applied. In FIG. 22A, a space 443 surrounded by the substrate 452, the adhesive layer 442, and the protective layer 121 is filled with an inert gas (such as nitrogen or argon), and a hollow encapsulation structure is applied. The adhesive layer 442 may be provided overlapping the light-emitting element. Further, the space 443 surrounded by the substrate 452, the adhesive layer 442, and the protective layer 121 may be filled with a resin different from the adhesive layer 442. Note that the configuration exemplified in Embodiment 1 can be applied to the protective layer 121.

[0269] In an opening provided in the insulating layer 214, the insulating layer 215, and the insulating layer 213 such that the upper surface of the conductive layer 222b included in the transistor 205 is exposed, a part of the conductive layer 418R, a part of the conductive layer 418G, and a part of the conductive layer 418B are formed along the bottom surface and the side surface of the opening. The conductive layer 418R, the conductive layer 418G, and the conductive layer 418B are each connected to the conductive layer 222b included in the transistor 205. Another part of the conductive layer 418R, the conductive layer 418G, and the conductive layer 418B is provided on the insulating layer 214.

[0270] On the conductive layer 418R, the conductive layer 418G, and the conductive layer 418B, pixel electrodes 111R, pixel electrodes 111G, and pixel electrodes 111B are provided.

[0271] As shown in FIG. 22A, an insulating layer 414 may be provided in a part between the conductive layer 418R and the pixel electrode 111R, a part between the conductive layer 418G and the pixel electrode 111G, and a part between the conductive layer 418B and the pixel electrode 111B. Specifically, the insulating layer 414 can be provided in an opening provided in the insulating layer 214, the insulating layer 215, and the insulating layer 213 and reaching the conductive layer 222b.

[0272] The pixel electrodes 111R, the pixel electrodes 111G, and the pixel electrodes 111B can adopt the pixel electrodes exemplified in Embodiment 1.

[0273] Protective layers 131, 132, and 133 are provided in the region between light-emitting element 110R and light-emitting element 110G, on the insulating layer 214, and in the region between light-emitting element 110G and light-emitting element 110B, on the insulating layer 214, respectively. The protective layers 131, 132, and 133 can be configured as illustrated in Embodiment 1.

[0274] The display device 100A is a top-emission type display device. Therefore, the light emitted by the light-emitting element 110 is emitted towards the substrate 452. It is preferable to use a material with high transmittance to visible light for the substrate 452.

[0275] Both transistors 201 and 205 are formed on the substrate 451. These transistors can be manufactured using the same materials and processes.

[0276] Insulating layers 211, 213, 215, and 214 are provided on the substrate 451 in this order. A portion of insulating layer 211 functions as a gate insulating layer for each transistor. A portion of insulating layer 213 functions as a gate insulating layer for each transistor. Insulating layer 215 is provided covering the transistors. Insulating layer 214 is provided covering the transistors and functions as a planarization layer. The number of gate insulating layers and insulating layers covering the transistors are not limited and may be a single layer or two or more layers, respectively.

[0277] It is preferable to use a material that does not easily allow impurities such as water and hydrogen to diffuse into at least one layer of the insulating layer covering the transistor. This allows the insulating layer to function as a barrier layer. With such a configuration, the diffusion of impurities from the outside into the transistor can be effectively suppressed, thereby improving the reliability of the display device.

[0278] It is preferable to use inorganic insulating films for insulating layer 211, insulating layer 213, and insulating layer 215. Examples of inorganic insulating films that can be used include silicon nitride film, silicon oxide nitride film, silicon oxide film, silicon nitride oxide film, aluminum oxide film, and aluminum nitride film. Alternatively, hafnium oxide film, yttrium oxide film, zirconium oxide film, gallium oxide film, tantalum oxide film, magnesium oxide film, lanthanum oxide film, cerium oxide film, and neodymium oxide film may also be used. Furthermore, two or more of the above insulating films may be laminated together.

[0279] 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 100A. This prevents impurities from entering through the organic insulating film from the edge of the display device 100A. Alternatively, the organic insulating film may be formed so that its edge is inward from the edge of the display device 100A, so that the organic insulating film is not exposed at the edge of the display device 100A.

[0280] For the insulating layer 214, which functions as a planarization layer, it is preferable to use an organic insulating film. Examples of materials that can be used as the organic insulating film include acrylic resins, polyimide resins, epoxy resins, polyamide resins, polyimidoamide resins, siloxane resins, benzocyclobutene resins, phenolic resins, and precursors of these resins.

[0281] In the region 228 shown in Figure 22A, openings are formed in the insulating layer 214, the protective layer 131 on the insulating layer 214, the insulating layer 132 on the protective layer 131, and the protective layer 133 on the insulating layer 132. A protective layer 121 is formed to cover the openings. By using an inorganic layer as the protective layer 121, even when an organic insulating film is used for the insulating layer 214, it is possible to suppress the intrusion of impurities into the display unit 462 from the outside through the insulating layer 214. Therefore, the reliability of the display device 100A can be improved.

[0282] Transistors 201 and 205 have a conductive layer 221 that functions as a gate, an insulating layer 211 that functions as a gate insulating layer, a conductive layer 222a that functions as one of the source and drain, a conductive layer 222b that functions as the other of the source and 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.

[0283] The transistor structure of the display device of this embodiment is not particularly limited. For example, a planar transistor, a staggered transistor, or an inverse staggered transistor can be used. Furthermore, either a top-gate or bottom-gate transistor structure may be used. Alternatively, gates may be provided above and below the semiconductor layer in which the channel is formed.

[0284] Transistors 201 and 205 are configured in which a semiconductor layer on which a channel is formed is sandwiched between two gates. The transistors may be driven by connecting the two gates and supplying them with the same signal. Alternatively, the threshold voltage of the transistors may be controlled by applying a potential to control the threshold voltage to one of the two gates and a potential to drive the other gate.

[0285] The crystallinity of the semiconductor material used in the transistor is not particularly limited; amorphous semiconductors and crystalline semiconductors (microcrystalline semiconductors, polycrystalline semiconductors, single-crystal semiconductors, or semiconductors having a crystalline region in part) may be used. Using a crystalline semiconductor is preferable because it can suppress the degradation of transistor characteristics.

[0286] The semiconductor layer of the transistor preferably has a metal oxide (also called an oxide semiconductor). In other words, the display device of this embodiment preferably uses a transistor (hereinafter also called an OS transistor) that uses a metal oxide in the channel formation region. Alternatively, the semiconductor layer of the transistor may have silicon. Examples of silicon include amorphous silicon and crystalline silicon (low-temperature polysilicon and single-crystal silicon, etc.).

[0287] The semiconductor layer preferably comprises, for example, indium, M (where M is one or more selected from gallium, aluminum, silicon, boron, yttrium, tin, copper, vanadium, beryllium, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, and magnesium), and zinc. In particular, it is preferable that M is one or more selected from aluminum, gallium, yttrium, and tin.

[0288] In particular, it is preferable to use an oxide containing indium (In), gallium (Ga), and zinc (Zn) (also written as IGZO) as the semiconductor layer. Alternatively, an oxide containing indium (In), aluminum (Al), and zinc (Zn) (also written as IAZO) may be used as the semiconductor layer. Alternatively, an oxide containing indium (In), aluminum (Al), gallium (Ga), and zinc (Zn) (IAGZO) may be used as the semiconductor layer.

[0289] When the semiconductor layer is an In-M-Zn oxide, it is preferable that the atomic ratio of In in the In-M-Zn oxide is equal to or greater than the atomic ratio of M. Examples of atomic ratios of metal elements in such In-M-Zn oxides include compositions where In:M:Zn=1:1:1 or close to it, In:M:Zn=1:1:1.2 or close to it, In:M:Zn=2:1:3 or close to it, In:M:Zn=3:1:2 or close to it, In:M:Zn=4:2:3 or close to it, In:M:Zn=4:2:4.1 or close to it, In:M:Zn=5:1:3 or close to it, In:M:Zn=5:1:6 or close to it, In:M:Zn=5:1:7 or close to it, In:M:Zn=5:1:8 or close to it, In:M:Zn=6:1:6 or close to it, In:M:Zn=5:2:5 or close to it, and so on. Note that "nearby composition" includes a range of ±30% of the desired atomic ratio.

[0290] For example, when describing an atomic ratio of In:Ga:Zn = 4:2:3 or a composition close to that, it includes cases where, when the atomic ratio of In is 4, the atomic ratio of Ga is between 1 and 3, and the atomic ratio of Zn is between 2 and 4. Also, when describing an atomic ratio of In:Ga:Zn = 5:1:6 or a composition close to that, it includes cases where, when the atomic ratio of In is 5, the atomic ratio of Ga is greater than 0.1 and 2 or less, and the atomic ratio of Zn is between 5 and 7. Furthermore, when describing an atomic ratio of In:Ga:Zn = 1:1:1 or a composition close to that, it includes cases where, when the atomic ratio of In is 1, the atomic ratio of Ga is greater than 0.1 and 2 or less, and the atomic ratio of Zn is greater than 0.1 and 2 or less.

[0291] The transistors in circuit 464 and the transistors in display unit 462 may have the same structure or different structures. The structures of the multiple transistors in circuit 464 may all be the same or there may be two or more different structures. Similarly, the structures of the multiple transistors in display unit 462 may all be the same or there may be two or more different structures.

[0292] A connection portion 204 is provided in the region of substrate 451 that does not overlap with substrate 452. At the connection portion 204, wiring 465 is electrically connected to FPC 472 via conductive layer 468, conductive layer 461, and connection layer 242. As conductive layer 468, a conductive layer obtained by processing the same conductive film as conductive layer 418 can be used. As conductive layer 461, a conductive layer obtained by processing the same conductive film as the pixel electrode 111, or a conductive layer obtained by processing a laminated film of the same conductive film as the pixel electrode 111 and the same conductive film as the optical adjustment layer can be used. On the upper surface of the connection portion 204, the conductive layer 461 is exposed. This allows the connection portion 204 and FPC 472 to be electrically connected via the connection layer 242. An insulating layer 414 may be provided in a part between conductive layer 468 and conductive layer 461. Specifically, an insulating layer 414 can be provided in the openings in the insulating layer 214, insulating layer 215, and insulating layer 213.

[0293] It is preferable to provide a light-shielding layer 417 on the surface of the substrate 452 that faces the substrate 451. Various optical components can also be arranged on the outside of the substrate 452. Examples of optical components include polarizing plates, phase difference plates, light diffusion layers (e.g., diffusion films), anti-reflective layers, and light-collecting films. Furthermore, an antistatic film to suppress the adhesion of dust, a water-repellent film to make it difficult for dirt to adhere, a hard coat film to suppress the occurrence of scratches during use, or an impact-absorbing layer may also be arranged on the outside of the substrate 452.

[0294] By providing a protective layer 121 that covers the light-emitting element 110, it is possible to suppress the ingress of impurities such as water into the light-emitting element 110 and improve the reliability of the light-emitting element 110.

[0295] In the region 228 near the edge of the display device 100A, it is preferable that the insulating layer 215 and the protective layer 121 are in contact with each other through an 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 121 are in contact with each other. This suppresses the entry of impurities into the display unit 462 from the outside through the organic insulating film. Therefore, the reliability of the display device 100A can be improved.

[0296] Substrates 451 and 452 can be made of glass, quartz, ceramic, sapphire, resin, metal, alloy, or semiconductor, respectively. The substrate on the side that extracts light from the light-emitting element 110 should be made of a material that transmits the light. Using flexible materials for substrates 451 and 452 can increase the flexibility of the display device. Alternatively, a polarizing plate may be used as substrate 451 or substrate 452.

[0297] Substrates 451 and 452 can be, respectively, polyester resins such as polyethylene terephthalate (PET) or polyethylene naphthalate (PEN), polyacrylonitrile resin, acrylic resin, polyimide resin, polymethyl methacrylate resin, polycarbonate (PC) resin, polyethersulfone (PES) resin, polyamide resin (nylon, aramid, etc.), polysiloxane resin, cycloolefin resin, polystyrene resin, polyamide-imide resin, polyurethane resin, polyvinyl chloride resin, polyvinylidene chloride resin, polypropylene resin, polytetrafluoroethylene (PTFE) resin, or ABS resin, cellulose nanofiber, etc. One or both of substrates 451 and 452 may be made of glass of a thickness sufficient to provide flexibility.

[0298] Furthermore, when a circular polarizing plate is superimposed on a display device, it is preferable to use a substrate with high optical isotropy for the substrate of the display device. A substrate with high optical isotropy can also be said to have low birefringence (low amount of birefringence).

[0299] For substrates with high optical isotropy, the absolute value of the retardation (phase difference) is preferably 30 nm or less, more preferably 20 nm or less, and even more preferably 10 nm or less.

[0300] Examples of films with high optical isotropy include triacetylcellulose (TAC, also known as cellulose triacetate) film, cycloolefin polymer (COP) film, cycloolefin copolymer (COC) film, and acrylic film.

[0301] Furthermore, when using a film as the substrate, the film may absorb water, potentially causing wrinkles or other shape changes 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 preferable to use a film with a water absorption rate of 0.1% or less, and even more preferable to use a film with a water absorption rate of 0.01% or less.

[0302] As the adhesive layer 442, various types of curing adhesives can be used, such as UV-curing adhesives, reaction-curing adhesives, thermosetting adhesives, or anaerobic adhesives. Examples of these adhesives include epoxy resins, acrylic resins, silicone resins, phenolic resins, polyimide resins, imide resins, PVC (polyvinyl chloride) resins, PVB (polyvinyl butyral) resins, and EVA (ethylene vinyl acetate) resins. Materials with low moisture permeability, such as epoxy resins, are particularly preferred. Two-component mixed resins may also be used. Alternatively, for example, an adhesive sheet may be used.

[0303] As the connecting layer 242, an anisotropic conductive film (ACF) or an anisotropic conductive paste (ACP) can be used.

[0304] Materials that can be used for conductive layers such as the gate, source, and drain of transistors, as well as various wirings and electrodes that constitute display devices, include metals such as aluminum, titanium, chromium, nickel, copper, yttrium, zirconium, molybdenum, silver, tantalum, and tungsten, as well as alloys mainly composed of these metals. Films containing these materials can be used as single layers or in a multilayer structure.

[0305] Furthermore, conductive oxides such as indium oxide, indium tin oxide, indium zinc oxide, zinc oxide, or zinc oxide containing gallium, or graphene can be used as the light-transmitting conductive material. Alternatively, metallic materials such as gold, silver, platinum, magnesium, nickel, tungsten, chromium, molybdenum, iron, cobalt, copper, palladium, and titanium, or alloy materials containing such metallic materials, can be used. Alternatively, nitrides of such metallic materials (e.g., titanium nitride) may be used. When using metallic materials or alloy materials (or their nitrides), it is preferable to make them thin enough to be light-transmitting. In addition, a laminated film of the above materials can be used as a conductive layer. For example, using a laminated film of a silver-magnesium alloy and indium tin oxide is preferable because it can enhance conductivity. These can also be used for conductive layers of various wirings and electrodes that constitute a display device, and for conductive layers of light-emitting elements (conductive layers that function as pixel electrodes or common electrodes).

[0306] Examples of insulating materials that can be used for each insulating layer include resins such as acrylic resin or epoxy resin, and inorganic insulating materials such as silicon oxide, silicon oxide nitride, silicon nitride, silicon nitride, or aluminum oxide.

[0307] Figure 22B is a cross-sectional view showing an example configuration of transistor 209, and Figure 22C is a cross-sectional view showing an example configuration of transistor 210. Transistors 209 and 210 can be applied to, for example, transistors 201 and 205 shown in Figure 22A.

[0308] Transistors 209 and 210 each have a conductive layer 221 that functions as a gate, an insulating layer 211 that functions as a gate insulating layer, a semiconductor layer 231 having a channel forming region 231i and a pair of low-resistance regions 231n, a conductive layer 222a connected to one of the pair of low-resistance regions 231n, a conductive layer 222b connected to the other of the pair of low-resistance regions 231n, an insulating layer 225 that functions as a gate insulating layer, a conductive layer 223 that functions as a gate, and an insulating layer 215 covering the conductive layer 223. The insulating layer 211 is located between the conductive layer 221 and the channel forming region 231i. The insulating layer 225 is located between the conductive layer 223 and the channel forming region 231i. An insulating layer 218 may also be provided to cover transistor 209 or transistor 210.

[0309] Conductive layer 222a and conductive layer 222b are connected to the low-resistance region 231n via openings provided in insulating layer 215 and insulating layer 225, respectively. Of the conductive layer 222a and conductive layer 222b, one functions as a source and the other as a drain.

[0310] Figure 22B shows an example in which the insulating layer 225 covers the top and sides of the semiconductor layer 231. The conductive layer 222a and conductive layer 222b are connected to the low-resistance region 231n through openings provided in the insulating layer 225 and insulating layer 215, respectively.

[0311] On the other hand, in the transistor 210 shown in Figure 22C, 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 Figure 22C can be fabricated by processing the insulating layer 225 using the conductive layer 223 as a mask. In Figure 22C, an insulating layer 215 is provided covering the insulating layer 225 and the conductive layer 223, and the conductive layer 222a and conductive layer 222b are connected to the low-resistance region 231n, respectively, through openings in the insulating layer 215.

[0312] Further, all the transistors included in the pixel circuit for driving the light-emitting element may use transistors having silicon in the semiconductor layer where channels are formed (hereinafter also referred to as Si transistors). Examples of silicon include single-crystalline silicon, polycrystalline silicon, and amorphous silicon. In particular, as the Si transistor, a transistor having low-temperature polysilicon (LTPS (Low Temperature Poly Silicon)) in the semiconductor layer (hereinafter also referred to as an LTPS transistor) can be preferably used. The LTPS transistor has high field-effect mobility and good frequency characteristics.

[0313] By using transistors using silicon such as LTPS transistors, a circuit (for example, a source driver circuit) that needs to be driven at a high frequency can be fabricated on the same substrate as the display unit. As a result, the external circuit mounted on the display device can be simplified, and the component cost and the mounting cost can be reduced.

[0314] Also, it is preferable to use, for at least one of the transistors included in the pixel circuit, a transistor having a metal oxide in the semiconductor where channels are formed. The OS transistor has an extremely high field-effect mobility compared to amorphous silicon. Also, the OS transistor has a significantly small leakage current between the source and the drain in the off state (hereinafter also referred to as the off current), and can hold the charge accumulated in the capacitor connected in series with the transistor for a long period of time. Also, by applying the OS transistor, the power consumption of the display device can be reduced.

[0315] Also, the off-current value of the OS transistor per 1 μm channel width at room temperature is 1 aA (1×10 -18 A) or less, 1 zA (1×10 -21 A) or less, or 1 yA (1×10 -24 A) or less. Note that the off-current value of the Si transistor per 1 μm channel width at room temperature is 1 fA (1×10 -15 A) or more and 1 pA (1×10 -12A) The answer is as follows. Therefore, it can be said that the off-current of an OS transistor is about 10 orders of magnitude lower than that of a Si transistor.

[0316] By using LTPS transistors in some of the transistors included in the pixel circuit and OS transistors in others, a display device with low power consumption and high driving capability can be realized. Furthermore, a configuration combining LTPS transistors and OS transistors is sometimes referred to as LTPO. A more suitable example is a configuration in which OS transistors are used as switches to control conduction and non-conduction between wiring, and LTPS transistors are used as transistors to control current.

[0317] For example, one of the transistors provided in the pixel circuit functions as a transistor for controlling the current flowing to the light-emitting element, and can be called a drive transistor. One of the source and drain of the drive transistor is electrically connected to the pixel electrode of the light-emitting element. It is preferable to use an LTPS transistor for this drive transistor. This makes it possible to increase the current flowing to the light-emitting element in the pixel circuit.

[0318] On the other hand, another transistor provided in the pixel circuit functions as a switch to control the selection and deselection of pixels, and can be called a selection transistor. The gate of the selection transistor is electrically connected to the gate line, and one of the source and drain is electrically connected to the source line (signal line). It is preferable to use an OS transistor for the selection transistor. This makes it possible to maintain the gradation of pixels even when the frame frequency is significantly reduced (e.g., 1 fps or less), and thus power consumption can be reduced by stopping the driver when displaying still images.

[0319] Thus, one aspect of the present invention makes it possible to realize a display device that combines a high aperture ratio, high resolution, high display quality, and low power consumption.

[0320] Furthermore, one embodiment of the present invention is a display device having an OS transistor and an MML (metal maskless) structure light-emitting element. This configuration makes it possible to extremely reduce the leakage current that can flow through the transistor and the leakage current that can flow between adjacent light-emitting elements (also called lateral leakage current or side leakage current). With this configuration, when an image is displayed on the display device, the observer can observe one or more of the following: image sharpness, image clarity, and a high contrast ratio. Moreover, by having an extremely low leakage current that can flow through the transistor and lateral leakage current between light-emitting elements, it is possible to achieve a display with virtually no light leakage that may occur when displaying black (also called a true black display).

[0321] [Display device 100B] Figure 23 is a cross-sectional view showing an example configuration of the display device 100B. The main difference between the display device 100B and the display device 100A is that the display device 100B is a bottom-emission type display device. Parts that are the same as those of the display device 100A are omitted from the explanation.

[0322] In the display device 100B, the light emitted by the light-emitting element 110 is emitted towards the substrate 451. It is preferable to use a material with high transmittance to visible light for the substrate 451. On the other hand, the light transmittance of the material used for the substrate 452 is not a requirement.

[0323] It is preferable to provide a light-shielding layer 417 between the substrate 451 and the transistor 201, and between the substrate 451 and the transistor 205. Figure 23 shows an example in which a light-shielding layer 417 is provided on the substrate 451, an insulating layer 253 is provided so as to cover the light-shielding layer 417, and transistors 201 and 205 are provided on the insulating layer 253. The insulating layer 253 can be made of the same material as that which can be used for insulating layers 211, 213, and 215.

[0324] The configuration examples illustrated in this embodiment, and the corresponding drawings, etc., can be appropriately combined with other configuration examples or drawings, etc., at least in part.

[0325] (Embodiment 3) This embodiment describes an example of a display device configuration different from the above embodiment.

[0326] The display device of this embodiment can be a high-definition display device. Therefore, the display device of this embodiment can be used, for example, in information terminals (wearable devices) such as wristwatches and bracelets, as well as in VR devices such as head-mounted displays, AR devices such as glasses, and in the display section of wearable devices that can be worn on the head.

[0327] [Display Module_2] Figure 24A shows a perspective view of the display module 280. The display module 280 includes a display device 100C and an FPC 290. Note that the display device included in the display module 280 is not limited to the display device 100C, but may also be the display device 100D, display device 100E, or display device 100F, which will be described later.

[0328] The display module 280 has substrates 291 and 292. The display module 280 has a display unit 281. The display unit 281 is an area in the display module 280 that displays an image, and is an area in which light from each pixel provided in the pixel unit 284, which will be described later, can be seen.

[0329] Figure 24B shows a schematic perspective view illustrating the configuration of the substrate 291. On the substrate 291, a circuit section 282, a pixel circuit section 283 on the circuit section 282, and a pixel section 284 on the pixel circuit section 283 are stacked. In addition, a terminal section 285 for connecting to the FPC 290 is provided in the portion of the substrate 291 that does not overlap with the pixel section 284. The terminal section 285 and the circuit section 282 are electrically connected by a wiring section 286, which is composed of multiple wires.

[0330] The pixel section 284 has a plurality of periodically arranged pixels 103. The right side of Figure 24B shows an enlarged view of one pixel 103. The pixel 103 has light-emitting elements 110R, 110G, and 110B, which emit light in different colors from each other. It is preferable that the plurality of light-emitting elements 110 be arranged in a stripe arrangement as shown in Figure 24B. By using a stripe arrangement, the light-emitting elements of one embodiment of the present invention can be arranged at high density, thereby providing a high-definition display device. Furthermore, various arrangement methods such as delta arrangement or pentile arrangement can be applied.

[0331] The pixel circuit section 283 has a plurality of pixel circuits 283a arranged periodically.

[0332] A single pixel circuit 283a is a circuit that controls the light emission of three light-emitting elements 110 that are present in a single pixel 103. A single pixel circuit 283a may be configured to have three circuits that control the light emission of a single light-emitting element 110. For example, a single pixel circuit 283a may have at least one selection transistor, one current control transistor (drive transistor), and a capacitor for each light-emitting element 110. In this case, a gate signal is input to the gate of the selection transistor, and a video signal is input to either the source or the drain. This realizes an active-matrix type display device.

[0333] The circuit section 282 has circuits for driving each pixel circuit 283a of the pixel circuit section 283. For example, it is preferable to have one or both of a scan line drive circuit and a signal line drive circuit. In addition, it may have at least one of the following: an arithmetic circuit, a memory circuit, and a power supply circuit.

[0334] The FPC290 functions as wiring for supplying video signals or power potential, etc., to the circuit section 282 from an external source. An IC may also be mounted on the FPC290.

[0335] The display module 280 can be configured such that one or both of the pixel circuit section 283 and the circuit section 282 are stacked on the lower side of the pixel section 284, thereby enabling an extremely high aperture ratio (effective display area ratio) of the display section 281. For example, the aperture ratio of the display section 281 can be 40% or more and less than 100%, preferably 50% or more and 95%, and more preferably 60% or more and 95%. Furthermore, it is possible to arrange the pixels 103 at an extremely high density, enabling an extremely high resolution of the display section 281. For example, it is preferable that the pixels 103 in the display section 281 are arranged with a resolution of 20000 ppi or more, preferably 3000 ppi or more, more preferably 5000 ppi or more, and even more preferably 6000 ppi or more, and with a resolution of 20000 ppi or less, or 30000 ppi or less.

[0336] Because such a display module 280 is extremely high-resolution, it can be suitably used in VR devices such as head-mounted displays, or in glasses-type AR devices. For example, even in a configuration where the display part of the display module 280 is viewed through lenses, the display module 280 has an extremely high-resolution display part 281, so even when the display part is magnified with lenses, pixels are not visible, allowing for a highly immersive display. Furthermore, the display module 280 is not limited to this, and can be suitably used in electronic devices with relatively small display parts. For example, it can be suitably used in the display part of wearable electronic devices such as watches.

[0337] [Display device 100C] The display device 100C shown in Figure 25 includes a substrate 301, light-emitting elements 110R, 110G, 110B, a capacitor 240, and a transistor 310.

[0338] The transistor 310 is a transistor having a channel-forming region in the substrate 301. The substrate 301 can be a semiconductor substrate such as a single-crystal silicon substrate. The transistor 310 comprises a portion of the substrate 301, a conductive layer 311, a low-resistance region 312, an insulating layer 313, and an insulating layer 314. The conductive layer 311 functions as a gate electrode. The insulating layer 313 is located between the substrate 301 and the conductive layer 311 and functions as a gate insulating layer. The low-resistance region 312 is a region of the substrate 301 doped with impurities and functions as a source or drain. The insulating layer 314 is provided covering the side surface of the conductive layer 311.

[0339] Furthermore, an element isolation layer 315 is provided between two adjacent transistors 310 so as to be embedded in the substrate 301.

[0340] Furthermore, an insulating layer 261 is provided to cover the transistor 310, and a capacitance 240 is provided on the insulating layer 261.

[0341] Capacitor 240 has a conductive layer 241, a conductive layer 245, and an insulating layer 243 located between them. The conductive layer 241 functions as one electrode of the capacitor 240, the conductive layer 245 functions as the other electrode of the capacitor 240, and the insulating layer 243 functions as the dielectric of the capacitor 240.

[0342] The conductive layer 241 is provided on the insulating layer 261 and embedded in the insulating layer 254. The conductive layer 241 is electrically connected to either the source or drain of the transistor 310 by a plug 271 embedded in the insulating layer 261. The insulating layer 243 is provided covering the conductive layer 241. The conductive layer 245 is provided in the region that overlaps with the conductive layer 241 via the insulating layer 243.

[0343] An insulating layer 255 is provided covering the capacitance 240, and light-emitting elements 110R, 110G, and 110B are provided on the insulating layer 255. A protective layer 121 is provided on the light-emitting elements 110R, 110G, and 110B, and a substrate 420 is bonded to the upper surface of the protective layer 121 by a resin layer 419.

[0344] Substrate 301 corresponds to substrate 291 in Figures 24A and 24B, and substrate 420 corresponds to substrate 292 in Figure 24A. Furthermore, the laminated structure from substrate 301 to insulating layer 255 corresponds to layer 101 containing the transistor in Embodiment 1.

[0345] The pixel electrodes 111 of the light-emitting element 110 are electrically connected to either the source or drain of the transistor 310 by plugs 256 embedded in the insulating layer 255 and insulating layer 243, a conductive layer 241 embedded in the insulating layer 254, and plugs 271 embedded in the insulating layer 261.

[0346] [Display device 100D] The display device 100D shown in Figure 26 differs from the display device 100C mainly in its transistor configuration. Note that explanations of parts similar to those of the display device 100C may be omitted.

[0347] Transistor 320 is a transistor in which a metal oxide is applied to the semiconductor layer where the channel is formed.

[0348] The transistor 320 has a semiconductor layer 321, an insulating layer 323, a conductive layer 324, a pair of conductive layers 325, an insulating layer 326, and a conductive layer 327.

[0349] Substrate 331 corresponds to substrate 291 in Figures 24A and 24B. An insulating substrate or a semiconductor substrate can be used as substrate 331.

[0350] An insulating layer 332 is provided on the substrate 331. The insulating layer 332 functions as a barrier layer that prevents impurities such as water or hydrogen from diffusing from the substrate 331 to the transistor 320, and prevents oxygen from detaching from the semiconductor layer 321 to the insulating layer 332. As the insulating layer 332, for example, a film that is less susceptible to hydrogen or oxygen diffusion than a silicon oxide film can be used, such as an aluminum oxide film, a hafnium oxide film, or a silicon nitride film.

[0351] A conductive layer 327 is provided on an insulating layer 332, and an insulating layer 326 is provided covering the conductive layer 327. The conductive layer 327 functions as the first gate electrode of the transistor 320, and a portion of the insulating layer 326 functions as the first gate insulating layer. It is preferable to use an oxide insulating film, such as a silicon oxide film, for at least the portion of the insulating layer 326 that is in contact with the semiconductor layer 321. It is preferable that the upper surface of the insulating layer 326 is flattened.

[0352] The semiconductor layer 321 is provided on the insulating layer 326. Preferably, the semiconductor layer 321 has a metal oxide film having semiconductor properties.

[0353] A pair of conductive layers 325 are provided in contact with the semiconductor layer 321 and function as source and drain electrodes.

[0354] Furthermore, an insulating layer 328 is provided covering the top and side surfaces of the pair of conductive layers 325, as well as the side surfaces of the semiconductor layer 321, and an insulating layer 264 is provided on the insulating layer 328. The insulating layer 328 functions as a barrier layer to prevent impurities such as water or hydrogen from diffusing into the semiconductor layer 321 from the insulating layer 264, etc., and to prevent oxygen from detaching from the semiconductor layer 321. As the insulating layer 328, an insulating film similar to that of the insulating layer 332 can be used.

[0355] An opening is provided in the insulating layer 328 and the insulating layer 264 that reaches the semiconductor layer 321. Inside this opening, the insulating layer 323 and the conductive layer 324 are embedded, in contact with the sides of the insulating layer 264, the insulating layer 328, and the conductive layer 325, as well as the upper surface of the semiconductor layer 321. The conductive layer 324 functions as a second gate electrode, and the insulating layer 323 functions as a second gate insulating layer.

[0356] The upper surfaces of the conductive layer 324, the insulating layer 323, and the insulating layer 264 are flattened so that their heights are roughly the same, and the insulating layer 329 and insulating layer 265 are provided covering them.

[0357] Insulating layers 264 and 265 function as interlayer insulating layers. Insulating layer 329 functions as a barrier layer to prevent impurities such as water or hydrogen from diffusing into the transistor 320 from insulating layer 265, etc. As insulating layer 329, an insulating film similar to that used for insulating layers 328 and 332 can be used.

[0358] A plug 274, which is electrically connected to one of the pair of conductive layers 325, is provided so as to be embedded in the insulating layers 265, 329, 264, and 328. Here, it is preferable that the plug 274 has a conductive layer 274a that covers the sides of the openings of each of the insulating layers 265, 329, 264, and 328, and a part of the upper surface of the conductive layer 325, and a conductive layer 274b that is in contact with the upper surface of the conductive layer 274a. In this case, it is preferable to use a conductive material that does not easily allow hydrogen and oxygen to diffuse as the conductive layer 274a.

[0359] In the display device 100D, the configuration from the insulating layer 254 to the substrate 420 is the same as in the display device 100C. In the display device 100D, the laminated structure from the substrate 331 to the insulating layer 255 corresponds to the layer 101 containing the transistor in Embodiment 1.

[0360] [Display device 100E] The display device 100E shown in Figure 27 has a configuration in which transistors 310A and 310B, each with a channel formed on a semiconductor substrate, are stacked.

[0361] The display device 100E has a configuration in which a substrate 301B on which transistors 310B, capacitors 240, and each light-emitting element 110 are provided, and a substrate 301A on which transistor 310A is provided are bonded together.

[0362] In the display device 100E, substrate 301A corresponds to substrate 291 in Figures 24A and 24B, and substrate 420 corresponds to substrate 292 in Figure 24A. Furthermore, the laminated structure from substrate 301A to insulating layer 255 corresponds to layer 101 containing the transistor in Embodiment 1.

[0363] The display device 100E is provided with a plug 343 that penetrates the substrate 301B. The plug 343 is electrically connected to a conductive layer 342 provided on the back surface of the substrate 301B (the surface side of the substrate 301A). On the other hand, the substrate 301A has a conductive layer 341 provided on an insulating layer 261.

[0364] The conductive layer 341 and the conductive layer 342 are joined together, thereby electrically connecting substrate 301A and substrate 301B.

[0365] It is preferable to use the same conductive material for conductive layer 341 and conductive layer 342. For example, a metal film containing an element selected from Al, Cr, Cu, Ta, Ti, Mo, and W, or a metal nitride film (titanium nitride film, molybdenum nitride film, or tungsten nitride film) composed of the above elements can be used. In particular, it is preferable to use copper for conductive layer 341 and conductive layer 342. This allows the application of Cu-Cu (copper-copper) direct bonding technology (a technology that achieves electrical conductivity by connecting Cu (copper) pads to each other). The conductive layer 341 and conductive layer 342 may be bonded via bumps.

[0366] [Display device 100F] The display device 100F shown in Figure 28 has a configuration in which a transistor 310 with a channel formed on a substrate 301 and a transistor 320 containing a metal oxide in the semiconductor layer where the channel is formed are stacked.

[0367] In the display device 100F, substrate 301 corresponds to substrate 291 in Figures 24A and 24B, and substrate 420 corresponds to substrate 292 in Figure 24A. Furthermore, the laminated structure from substrate 301 to insulating layer 255 corresponds to layer 101 containing the transistor in Embodiment 1.

[0368] An insulating layer 261 is provided covering the transistor 310, and a conductive layer 251 is provided on the insulating layer 261. An insulating layer 262 is provided covering the conductive layer 251, and a conductive layer 252 is provided on the insulating layer 262. The conductive layers 251 and 252 each function as wiring. An insulating layer 263 and an insulating layer 332 are provided covering the conductive layer 252, and a transistor 320 is provided on the insulating layer 332. An insulating layer 265 is provided covering the transistor 320, and a capacitor 240 is provided on the insulating layer 265. The capacitor 240 and the transistor 320 are electrically connected by a plug 274.

[0369] Transistor 320 can be used as a transistor constituting a pixel circuit. Transistor 310 can also be used as a transistor constituting a pixel circuit, or as a transistor constituting a drive circuit (scan line drive circuit or signal line drive circuit) for driving the pixel circuit. Furthermore, transistors 310 and 320 can be used as transistors constituting various circuits such as arithmetic circuits or memory circuits.

[0370] This configuration allows for the formation of not only pixel circuits but also, for example, driving circuits directly beneath the light-emitting elements, making it possible to miniaturize the display device compared to cases where the driving circuits are located around the display area.

[0371] The configuration examples illustrated in this embodiment, and the corresponding drawings, etc., can be appropriately combined with other configuration examples or drawings, etc., at least in part.

[0372] (Embodiment 4) This embodiment describes a light-emitting element that can be used in a display device according to one aspect of the present invention.

[0373] <Example of light-emitting element configuration> As shown in Figure 29A, the light-emitting element has an EL layer 786 between a pair of electrodes (lower electrode 772, upper electrode 788). The EL layer 786 can be composed of multiple layers, such as layer 4420, light-emitting layer 4411, and layer 4430. Layer 4420 may include, for example, a layer containing a material with high electron injection properties (electron injection layer) and a layer containing a material with high electron transport properties (electron transport layer). Light-emitting layer 4411 may include, for example, a light-emitting compound. Layer 4430 may include, for example, a layer containing a material with high hole injection properties (hole injection layer) and a layer containing a material with high hole transport properties (hole transport layer).

[0374] A configuration having a layer 4420, a light-emitting layer 4411, and a layer 4430 provided between a pair of electrodes can function as a single light-emitting unit, and in this specification, the configuration shown in Figure 29A is referred to as a single structure.

[0375] Furthermore, Figure 29B shows a modified example of the EL layer 786 of the light-emitting element shown in Figure 29A. Specifically, the light-emitting element shown in Figure 29B has a layer 4430-1 on the lower electrode 772, a layer 4430-2 on layer 4430-1, a light-emitting layer 4411 on layer 4430-2, a layer 4420-1 on the light-emitting layer 4411, a layer 4420-2 on layer 4420-1, and an upper electrode 788 on layer 4420-2. For example, when the lower electrode 772 is the anode and the upper electrode 788 is the cathode, layer 4430-1 functions as a hole injection layer, layer 4430-2 functions as a hole transport layer, layer 4420-1 functions as an electron transport layer, and layer 4420-2 functions as an electron injection layer. Alternatively, when the lower electrode 772 is used as the cathode and the upper electrode 788 is used as the anode, layer 4430-1 functions as an electron injection layer, layer 4430-2 functions as an electron transport layer, layer 4420-1 functions as a hole transport layer, and 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 within the light-emitting layer 4411.

[0376] Furthermore, as shown in Figures 29C and 29D, a configuration in which multiple light-emitting layers (light-emitting layer 4411, light-emitting layer 4412, and light-emitting layer 4413) are provided between layer 4420 and layer 4430 is also a variation of the single structure.

[0377] Furthermore, as shown in Figures 29E and 29F, a configuration in which multiple light-emitting units (EL layer 786a, EL layer 786b) are connected in series via an intermediate layer (charge generation layer) 4440 is referred to as a tandem structure in this specification. In this specification, the configuration shown in Figures 29E and 29F is referred to as a tandem structure, but it is not limited to this, and for example, a tandem structure may also be called a stack structure. By using a tandem structure, a light-emitting element capable of high-brightness light emission can be made.

[0378] In Figures 29C and 29D, the light-emitting layers 4411, 4412, and 4413 may be made of light-emitting materials that emit light of the same color, or even the same light-emitting material. For example, the light-emitting layers 4411, 4412, and 4413 may be made of light-emitting materials that emit blue light. A color conversion layer may be provided as layer 785 as shown in Figure 29D.

[0379] Furthermore, light-emitting materials that emit light of different colors may be used for the light-emitting layers 4411, 4412, and 4413. If the light emitted by the light-emitting layers 4411, 4412, and 4413 are complementary colors, white light emission can be obtained. A color filter (also called a colored layer) may be provided as layer 785 as shown in Figure 29D. By passing white light through the color filter, light of a desired color can be obtained.

[0380] Furthermore, in Figures 29E and 29F, the light-emitting layer 4411 and the light-emitting layer 4412 may use light-emitting materials that emit light of the same color, or even the same light-emitting material. Alternatively, the light-emitting layer 4411 and the light-emitting layer 4412 may use light-emitting materials that emit light of different colors. 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. Figure 29F shows an example in which a further layer 785 is provided. As layer 785, one or both of a color conversion layer and a color filter (coloring layer) can be used.

[0381] Furthermore, in Figures 29C, 29D, 29E, and 29F, as shown in Figure 29B, layer 4420 and layer 4430 may be a laminated structure consisting of two or more layers.

[0382] A structure in which each light-emitting element produces a different emission color (for example, blue (B), green (G), and red (R)) is sometimes called an SBS (Side By Side) structure.

[0383] The light-emitting color of the light-emitting element can be red, green, blue, cyan, magenta, yellow, or white, depending on the material constituting the EL layer 786. Furthermore, the color purity can be further enhanced by adding a microcavity structure to the light-emitting element.

[0384] A light-emitting element that emits white light preferably has a configuration that includes two or more types of light-emitting materials in its light-emitting layer. To obtain white light emission, it is sufficient to select light-emitting materials such that the light emitted by each of the two or more materials is complementary in color. For example, by making the light-emitting color of the first light-emitting layer and the light-emitting color of the second light-emitting layer complementary in color, a light-emitting element that emits white light as a whole can be obtained. The same applies to light-emitting elements that have three or more light-emitting layers.

[0385] The light-emitting layer preferably contains two or more light-emitting materials that emit light such as R (red), G (green), B (blue), Y (yellow), or O (orange).

[0386] This embodiment can be combined with other embodiments as appropriate.

[0387] (Embodiment 5) This embodiment describes metal oxides that can be used in the OS transistor described in the above embodiment.

[0388] The metal oxide preferably contains at least indium or zinc. It is particularly preferable that it contains indium and zinc. In addition, it is preferable that it contains aluminum, gallium, yttrium, or tin. It may also contain one or more selected from boron, silicon, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, magnesium, cobalt, etc.

[0389] Furthermore, metal oxides can be formed by sputtering, CVD methods such as MOCVD, or ALD methods.

[0390] <Classification of crystal structures> Examples of crystalline structures for oxide semiconductors include amorphous (including completely amorphous), CAAC (c-axis-aligned crystalline), nc (nanocrystalline), CAC (cloud-aligned composite), single crystal, and polycrystal.

[0391] The crystal structure of a film or substrate can be evaluated using X-ray diffraction (XRD) spectroscopy. For example, it can be evaluated using the XRD spectrum obtained by GIXD (Grazing-Incidence XRD) measurement. The GIXD method is also known as the thin-film method or the Seemann-Bohlin method.

[0392] For example, in a quartz glass substrate, the peak shape of the XRD spectrum is nearly symmetrical. On the other hand, in an IGZO film with a crystalline structure, the peak shape of the XRD spectrum is asymmetrical. The asymmetrical shape of the XRD spectrum peak 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.

[0393] Furthermore, the crystalline structure of a film or substrate can be evaluated by the diffraction pattern (also called the nano-beam electron diffraction pattern) observed using nano-beam 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. In contrast, a spot-like pattern is observed in the diffraction pattern of an IGZO film deposited at room temperature, rather than a halo. Therefore, it is presumed that an IGZO film deposited at room temperature is in an intermediate state, neither crystalline nor amorphous, and cannot be concluded to be in an amorphous state.

[0394] <<Oxide semiconductor structure>> It should be noted that oxide semiconductors may be classified differently from those described above when considering their structure. For example, oxide semiconductors can be divided into single-crystal oxide semiconductors and other non-single-crystal oxide semiconductors. Examples of non-single-crystal oxide semiconductors include the aforementioned CAAC-OS and nc-OS. Furthermore, non-single-crystal oxide semiconductors include polycrystalline oxide semiconductors, pseudo-amorphous oxide semiconductors (a-like OS: amorphous-like oxide semiconductors), and amorphous oxide semiconductors.

[0395] Here, we will explain the details of the CAAC-OS, nc-OS, and a-like OS mentioned above.

[0396] [CAAC-OS] CAAC-OS is an oxide semiconductor having multiple crystalline regions, the c-axis of which is oriented in a specific direction. This specific direction is the thickness direction of the CAAC-OS film, the normal direction to the surface on which the CAAC-OS film is formed, or the normal direction to the surface of the CAAC-OS film. A crystalline region is a region with periodic atomic arrangement. If we consider the atomic arrangement as a lattice arrangement, then a crystalline region is also a region with a aligned lattice arrangement. Furthermore, CAAC-OS has regions where multiple crystalline regions are connected in the ab-plane direction, and these regions may exhibit distortion. Distortion refers to a point in the connected region where the orientation of the lattice arrangement changes between a region with a aligned lattice arrangement and another region with a aligned lattice arrangement. In short, CAAC-OS is an oxide semiconductor that is c-axis oriented and does not exhibit clear orientation in the ab-plane direction.

[0397] Each of the above-mentioned 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 one minute crystal, the maximum diameter of that crystalline region will be less than 10 nm. When a crystalline region is composed of many minute crystals, the size of that crystalline region may be around several tens of nanometers.

[0398] Furthermore, in In-M-Zn oxides (where element M is one or more elements selected from aluminum, gallium, yttrium, tin, titanium, etc.), CAAC-OS tends to have a layered crystalline structure (also called a layered structure) consisting of layers containing indium (In) and oxygen (hereinafter referred to as the In layer) and layers containing element M, zinc (Zn), and oxygen (hereinafter referred to as the (M,Zn) layer). Note that indium and element M are mutually substitutable. Therefore, the (M,Zn) layer may contain indium. Also, the In layer may contain element M. Also, the In layer may contain Zn. This layered structure can be observed, for example, as a lattice image in high-resolution TEM (Transmission Electron Microscope) images.

[0399] When structural analysis of a CAAC-OS film is performed using, for example, an XRD instrument, out-of-plane XRD measurements using θ / 2θ scanning show a peak indicating c-axis orientation at 2θ = 31° or nearby. Note that the position of the peak indicating c-axis orientation (value of 2θ) may vary depending on the type and composition of the metal elements constituting the CAAC-OS.

[0400] Furthermore, for example, multiple bright spots are observed in the electron diffraction pattern of a CAAC-OS film. These spots are observed at point-symmetric positions with respect to the incident electron beam spot (also called the direct spot) that passed through the sample.

[0401] When the crystal region is observed from the specific direction described above, the lattice arrangement within that crystal region is based on a hexagonal lattice, but the unit cell is not necessarily a regular hexagon and may be non-regular hexagonal. Furthermore, the strain may have a pentagonal or heptagonal lattice arrangement. Moreover, in CAAC-OS, clear grain boundaries cannot be observed even near the strain. In other words, it can be seen that the formation of grain boundaries is suppressed by the strain in the lattice arrangement. This is thought to be because CAAC-OS can tolerate strain due to the fact that the arrangement of oxygen atoms is not dense in the ab-plane direction, and the bond distance between atoms changes due to the substitution of metal atoms.

[0402] A crystal structure in which clear grain boundaries can be observed is known as a polycrystal. Grain boundaries act as recombination centers, trapping carriers and potentially causing a decrease in the transistor's on-current and field-effect mobility. Therefore, CAAC-OS, which does not exhibit clear grain boundaries, is one of the crystalline oxides with a suitable crystal structure for the semiconductor layer of a transistor. Furthermore, a structure containing Zn is preferred for the composition of CAAC-OS. For example, In-Zn oxide and In-Ga-Zn oxide are preferred because they suppress the generation of grain boundaries more effectively than In oxide.

[0403] CAAC-OS is an oxide semiconductor with high crystallinity and no clearly defined grain boundaries. Therefore, CAAC-OS is less susceptible to the decrease in electron mobility caused by grain boundaries. Furthermore, since the crystallinity of oxide semiconductors can decrease due to the inclusion of impurities and the generation of defects, CAAC-OS can be said to be an oxide semiconductor with few impurities and defects (such as oxygen vacancies). Consequently, oxide semiconductors containing CAAC-OS have stable physical properties. Therefore, oxide semiconductors containing CAAC-OS are heat-resistant and highly reliable. In addition, CAAC-OS is stable even at high temperatures (so-called thermal budget) during the manufacturing process. Therefore, using CAAC-OS in OS transistors allows for greater flexibility in the manufacturing process.

[0404] [nc-OS] nc-OS exhibits periodicity in atomic arrangement in minute regions (e.g., regions between 1 nm and 10 nm, particularly between 1 nm and 3 nm). In other words, nc-OS contains minute crystals. These minute crystals are also called nanocrystals because their size is, for example, between 1 nm and 10 nm, particularly between 1 nm and 3 nm. Furthermore, nc-OS shows no regularity in crystal orientation between different nanocrystals. Therefore, no orientation is observed throughout the film. Consequently, depending on the analytical method, nc-OS may be indistinguishable from a-like OS or amorphous oxide semiconductors. For example, when structural analysis of an nc-OS film is performed using an XRD instrument, no peaks indicating crystallinity are detected in out-of-plane XRD measurements using θ / 2θ scanning. Also, when electron diffraction (also called limited-field electron diffraction) is performed on an nc-OS film using an electron beam with a probe diameter larger than that of the nanocrystals (e.g., 50 nm or larger), a diffraction pattern resembling a halo pattern is observed. On the other hand, when electron diffraction (also called nanobeam electron diffraction) is performed on an nc-OS film using an electron beam with a probe diameter close to or smaller than the size of the nanocrystal (for example, 1 nm to 30 nm), an electron diffraction pattern may be obtained in which multiple spots are observed within a ring-shaped region centered on a direct spot.

[0405] [a-like OS] a-like OS is an oxide semiconductor having a structure between nc-OS and amorphous oxide semiconductors. a-like OS has porous or low-density regions. That is, a-like OS has lower crystallinity compared to nc-OS and CAAC-OS. Also, a-like OS has a higher hydrogen concentration in the film compared to nc-OS and CAAC-OS.

[0406] <<Oxide Semiconductor Composition>> Next, we will explain the details of CAC-OS mentioned above. Note that CAC-OS refers to the material composition.

[0407] [CAC-OS] CAC-OS is a material composition in which, for example, the elements constituting the metal oxide are unevenly distributed in sizes of 0.5 nm to 10 nm, preferably 1 nm to 3 nm, or close to that size. In the following, a state in which one or more metal elements are unevenly distributed in a metal oxide, and the regions containing the metal elements are mixed in sizes of 0.5 nm to 10 nm, preferably 1 nm to 3 nm, or close to that size, is also referred to as a mosaic or patchy state.

[0408] Furthermore, CAC-OS is a composite metal oxide having a mosaic-like structure formed by the separation of the material into a first region and a second region, with the first region distributed within the film (hereinafter also referred to as a cloud-like structure). In other words, CAC-OS is a composite metal oxide having a structure in which the first region and the second region are mixed.

[0409] Here, the atomic ratios of In, Ga, and Zn to the metal elements constituting the CAC-OS in In-Ga-Zn oxide are denoted as [In], [Ga], and [Zn], respectively. For example, in the CAC-OS of In-Ga-Zn oxide, the first region is the region where [In] is greater than the [In] in the composition of the CAC-OS film. The second region is the region where [Ga] is greater than the [Ga] in the composition of the CAC-OS film. Alternatively, for example, the first region is the region where [In] is greater than the [In] in the second region, and [Ga] is smaller than the [Ga] in the second region. The second region is the region where [Ga] is greater than the [Ga] in the first region, and [In] is smaller than the [In] in the first region.

[0410] Specifically, the first region described above is a region whose main component is indium oxide or indium zinc oxide, etc. The second region described above is a region whose main component is gallium oxide or gallium zinc oxide, etc. In other words, the first region can be rephrased as a region whose main component is In. Similarly, the second region can be rephrased as a region whose main component is Ga.

[0411] Furthermore, a clear boundary may not be observed between the first region and the second region described above.

[0412] Furthermore, CAC-OS in In-Ga-Zn oxide refers to a material composition containing In, Ga, Zn, and O, in which regions with Ga as the main component and regions with In as the main component are arranged in a mosaic-like manner, with these regions existing randomly. Therefore, it is presumed that CAC-OS has a structure in which metal elements are unevenly distributed.

[0413] CAC-OS can be formed, for example, by sputtering under conditions where the substrate is not heated. When forming CAC-OS by sputtering, one or more gases selected from inert gases (typically argon), oxygen gas, and nitrogen gas may be used as the film-forming gas. Furthermore, it is preferable that the ratio of the oxygen gas flow rate to the total flow rate of the film-forming gas during film formation be as low as possible. For example, it is preferable that the ratio of the oxygen gas flow rate to the total flow rate of the film-forming gas during film formation be 0% or more and less than 30%, preferably 0% or more and 10% or less.

[0414] Furthermore, for example, in the case of CAC-OS in In-Ga-Zn oxide, EDX mapping obtained using energy dispersive X-ray spectroscopy (EDX) confirms that it has a structure in which regions mainly composed of In (first region) and regions mainly composed of Ga (second region) are unevenly distributed and mixed.

[0415] Here, the first region is a region with higher conductivity compared to the second region. In other words, the conductivity of the metal oxide is exhibited when carriers flow through the first region. Therefore, a high field-effect mobility (μ) can be achieved when the first region is distributed in a cloud-like manner within the metal oxide.

[0416] On the other hand, the second region is a region with higher insulating properties compared to the first region. In other words, the distribution of the second region within the metal oxide can suppress leakage current.

[0417] Therefore, when CAC-OS is used in a transistor, the conductivity due to the first region and the insulation due to the second region work complementaryly to give CAC-OS a switching function (on / off function). In other words, CAC-OS has conductive function in part of the material, insulating function in part of the material, and semiconductor function as a whole. By separating the conductive function and the insulating function, both functions can be maximized. Therefore, by using CAC-OS in a transistor, a high on-current (I on ), high field-effect mobility (μ), and good switching operation can be achieved.

[0418] Furthermore, transistors using CAC-OS offer high reliability. Therefore, CAC-OS is ideal for various semiconductor devices, including display devices.

[0419] Oxide semiconductors can take on diverse structures, each possessing different properties. One embodiment of the present invention may include two or more of the following: amorphous oxide semiconductors, polycrystalline oxide semiconductors, a-like OS, CAC-OS, nc-OS, and CAAC-OS.

[0420] <Transistors containing oxide semiconductors> Next, we will explain the case where the above oxide semiconductor is used in a transistor.

[0421] By using the above-mentioned oxide semiconductor in transistors, it is possible to realize transistors with high field-effect mobility. Furthermore, it is possible to realize highly reliable transistors.

[0422] It is preferable to use an oxide semiconductor with a low carrier concentration for the transistor. For example, the carrier concentration of an oxide semiconductor is 1 × 10⁻⁶. 17 cm -3 The following is preferably 1 × 10 15 cm -3 More preferably 1 × 10 13 cm-3 More preferably 1 × 10 11 cm -3 More preferably 1 × 10 10 cm -3 It is less than 1 × 10 -9 cm -3 This concludes the explanation. Furthermore, when lowering the carrier concentration of an oxide semiconductor film, the impurity concentration in the oxide semiconductor film should be lowered to reduce the defect level density. In this specification, a low impurity concentration and low defect level density are referred to as high-purity intrinsic or substantially high-purity intrinsic. Note that an oxide semiconductor with a low carrier concentration may be referred to as a high-purity intrinsic or substantially high-purity intrinsic oxide semiconductor.

[0423] Furthermore, oxide semiconductor films that are highly pure or substantially highly pure have a low defect level density, which may result in a low trap level density.

[0424] Furthermore, charges trapped in the trap levels of oxide semiconductors can take a long time to disappear, sometimes behaving like fixed charges. Therefore, transistors in which channel formation regions are formed in oxide semiconductors with a high trap level density may exhibit unstable electrical properties.

[0425] Therefore, reducing the impurity concentration in the oxide semiconductor is effective in stabilizing the electrical characteristics of the 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, or silicon.

[0426] <Impurities> Here, we will explain the effects of various impurities in oxide semiconductors.

[0427] In oxide semiconductors, the presence of silicon or carbon, which are Group 14 elements, leads to the formation of defect levels 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 compared by 2 × 10⁻⁶. 18 atoms / cm 3 The following is preferably 2 × 10 17 atoms / cm 3 The following applies:

[0428] Furthermore, if an oxide semiconductor contains alkali metals or alkaline earth metals, it may form defect levels and generate carriers. Therefore, transistors using oxide semiconductors containing alkali metals or alkaline earth metals tend to exhibit normally-on characteristics. For this reason, the concentration of alkali metals or alkaline earth metals in the oxide semiconductor obtained by SIMS should be set to 1 × 10⁻⁶. 18 atoms / cm 3 The following is preferably 2 × 10 16 atoms / cm 3 Do the following:

[0429] Furthermore, in oxide semiconductors, the presence of nitrogen generates electrons, which act as carriers, increasing the carrier concentration and making it easier for the semiconductor to become n-type. As a result, transistors using oxide semiconductors containing nitrogen tend to exhibit normally-on characteristics. Alternatively, the presence of nitrogen in oxide semiconductors can lead to the formation of trap levels. As a result, the electrical properties of the transistor may become unstable. Therefore, the nitrogen concentration in oxide semiconductors obtained by SIMS should be set to 5 × 10⁻⁶. 19 atoms / cm 3 Less than 5 × 10 18 atoms / cm 3 More preferably 1 × 10 18 atoms / cm 3 More preferably 5 × 10 17 atoms / cm 3 Do the following:

[0430] Furthermore, hydrogen contained in oxide semiconductors can react with oxygen bonded to metal atoms to form water, potentially creating oxygen vacancies. Hydrogen can then fill these vacancies, generating electrons, which act as carriers. Additionally, some of the hydrogen can combine with oxygen bonded to metal atoms to generate electrons. Therefore, transistors using oxide semiconductors containing hydrogen tend to exhibit normally-on characteristics. For this reason, it is preferable to reduce the hydrogen content in oxide semiconductors as much as possible. Specifically, in oxide semiconductors, the hydrogen concentration obtained by SIMS should be 1 × 10⁻⁶. 20 atoms / cm 3 Less than 1 × 10 19 atoms / cm 3 Less than 5x10 18 atoms / cm 3 Less than 1 × 10 18 atoms / cm 3 Make it less than.

[0431] By using an oxide semiconductor with sufficiently reduced impurities in the channel formation region of a transistor, stable electrical characteristics can be provided.

[0432] This embodiment can be implemented in appropriate combination with other embodiments described herein, at least in part.

[0433] (Embodiment 6) This embodiment describes an electronic device according to one aspect of the present invention.

[0434] The electronic device of this embodiment has a display device according to one aspect of the present invention. The display device according to one aspect of the present invention is easily made high-definition, high-resolution, and large-scale. Therefore, the display device according to one aspect of the present invention can be used in the display units of various electronic devices.

[0435] Furthermore, since the display device according to one aspect of the present invention can be manufactured at a low cost, the manufacturing cost of electronic devices can be reduced.

[0436] Examples of electronic devices include television sets, desktop or notebook personal computers, computer monitors, digital signage, large game machines such as pachinko machines, and other electronic devices with relatively large screens, as well as digital cameras, digital video cameras, digital photo frames, mobile phones, portable game consoles, personal digital assistants, and audio playback devices.

[0437] In particular, a display device according to one aspect of the present invention can be used suitably in electronic devices having a relatively small display area because it can increase resolution. Examples of such electronic devices include information terminals (wearable devices) such as wristwatches or bracelets, and wearable devices that can be worn on the head, such as VR devices such as head-mounted displays or AR devices such as glasses. Wearable devices also include devices for SR and MR.

[0438] A display device according to one aspect of the present invention preferably has an extremely high resolution such as HD (1280 x 720 pixels), FHD (1920 x 1080 pixels), WQHD (2560 x 1440 pixels), WQXGA (2560 x 1600 pixels), 4K2K (3840 x 2160 pixels), or 8K4K (7680 x 4320 pixels). In particular, a resolution of 4K2K, 8K4K, or higher is preferred. Furthermore, the pixel density (resolution) of the display device according to one aspect of the present invention is preferably 300 ppi or more, more preferably 500 ppi or more, more preferably 1000 ppi or more, more preferably 2000 ppi or more, more preferably 3000 ppi or more, more preferably 5000 ppi or more, and even more preferably 7000 ppi or more. By using display devices with such high resolution or high detail, it becomes possible to further enhance the sense of presence and depth in portable or personal-use electronic devices for home use.

[0439] The electronic device of this embodiment can be incorporated along the curved surfaces of the interior or exterior walls of a house or building, or the interior or exterior of an automobile.

[0440] The electronic device in this embodiment may have an antenna. By receiving signals with the antenna, the display unit can display images and information. Furthermore, if the electronic device has an antenna and a secondary battery, the antenna may be used for contactless power transmission.

[0441] The electronic device of this embodiment may have sensors (including those with the function of measuring force, displacement, position, velocity, acceleration, angular velocity, rotational speed, distance, light, liquid, magnetism, temperature, chemical substances, sound, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, gradient, vibration, odor, or infrared radiation).

[0442] The electronic device of this embodiment can have a variety of functions. For example, it can have a function to display various information (still images, videos, and text images, etc.) on a display unit, a touch panel function, a function to display a calendar, date or time, a function to execute various software (programs), a wireless communication function, and a function to read programs or data recorded on a recording medium.

[0443] The electronic device 6500 shown in Figure 30A is a portable information terminal that can be used as a smartphone.

[0444] The electronic device 6500 includes a housing 6501, a display unit 6502, a power button 6503, a button 6504, a speaker 6505, a microphone 6506, a camera 6507, and a light source 6508, etc. The display unit 6502 has a touch panel function.

[0445] A display device according to one aspect of the present invention can be applied to the display unit 6502.

[0446] Figure 30B is a cross-sectional view of the housing 6501 including the end on the microphone 6506 side.

[0447] A light-transmitting protective member 6510 is provided on the display side of the housing 6501, and the display panel 6511, optical member 6512, touch sensor panel 6513, printed circuit board 6517, and battery 6518 are arranged in the space enclosed by the housing 6501 and the protective member 6510.

[0448] The protective member 6510 is fixed to the display panel 6511, the optical member 6512, and the touch sensor panel 6513 by an adhesive layer (not shown).

[0449] In the area outside the display unit 6502, a portion of the display panel 6511 is folded back, and the FPC 6515 is connected to this folded portion. IC 6516 is mounted on the FPC 6515. The FPC 6515 is connected to terminals provided on the printed circuit board 6517.

[0450] A flexible display (a display device with flexibility) according to one embodiment of the present invention can be applied to the display panel 6511. As a result, an extremely lightweight electronic device can be realized. Furthermore, because the display panel 6511 is extremely thin, a large-capacity battery 6518 can be installed while keeping the thickness of the electronic device low. In addition, by folding back a part of the display panel 6511 and placing the connection part with the FPC 6515 on the back of the pixel area, an electronic device with a narrow bezel can be realized.

[0451] Figure 31A shows an example of a television system. The television system 7100 has a display unit 7000 incorporated into a housing 7101. Here, the housing 7101 is shown supported by a stand 7103.

[0452] A display device according to one embodiment of the present invention can be applied to the display unit 7000.

[0453] The television device 7100 shown in Figure 31A can be operated using the operation switches on the housing 7101 and a separate remote control unit 7111. Alternatively, the display unit 7000 may be equipped with a touch sensor, and the television device 7100 can be operated, for example, by touching the display unit 7000 with a finger. The remote control unit 7111 may have a display unit that displays information output from the remote control unit 7111. Channels and volume can be controlled and the image displayed on the display unit 7000 can be controlled using the operation keys or touch panel on the remote control unit 7111.

[0454] The television system 7100 is configured to include a receiver and a modem. 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 sender to receiver) or two-way (between sender and receiver, or between receivers, etc.) information communication.

[0455] Figure 31B shows an example of a notebook personal computer. The notebook personal computer 7200 has a casing 7211, a keyboard 7212, a pointing device 7213, and an external connection port 7214, etc. A display unit 7000 is incorporated into the casing 7211.

[0456] A display device according to one embodiment of the present invention can be applied to the display unit 7000.

[0457] Figures 31C and 31D show examples of digital signage.

[0458] The digital signage 7300 shown in Figure 31C includes a housing 7301, a display unit 7000, and a speaker 7303, etc. Furthermore, it may include LED lamps, operation keys (including a power switch or operation switch), connection terminals, various sensors, and a microphone, etc.

[0459] Figure 31D shows a digital signage 7400 mounted on a cylindrical column 7401. The digital signage 7400 has a display unit 7000 that is provided along the curved surface of the column 7401.

[0460] In Figures 31C and 31D, a display device according to one embodiment of the present invention can be applied to the display unit 7000.

[0461] The larger the display area 7000, the more information can be provided at once. Furthermore, a larger display area 7000 is more eye-catching, which can, for example, enhance the effectiveness of advertising.

[0462] 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 users to operate it intuitively. Furthermore, when used for purposes such as providing route information or traffic information, intuitive operation can enhance usability.

[0463] Furthermore, as shown in Figures 31C and 31D, it is preferable that the digital signage 7300 or digital signage 7400 can be linked wirelessly with an information terminal 7311 or information terminal 7411 such as a smartphone owned by the user. For example, the advertising information displayed on the display unit 7000 can be displayed on the screen of the information terminal 7311 or information terminal 7411. Also, the display on the display unit 7000 can be switched by operating the information terminal 7311 or information terminal 7411.

[0464] Furthermore, the digital signage 7300 or digital signage 7400 can be used to run games using the screen of the information terminal 7311 or information terminal 7411 as the control device (controller). This allows a large number of users to participate in and enjoy the game simultaneously.

[0465] Figure 32A shows the external appearance of the camera 8000 with the viewfinder 8100 attached.

[0466] The camera 8000 includes a housing 8001, a display unit 8002, operation buttons 8003, and a shutter button 8004, etc. A detachable lens 8006 is also attached to the camera 8000. The lens 8006 and the housing of the camera 8000 may be integrated into a single unit.

[0467] Camera 8000 can take an image by pressing the shutter button 8004 or by touching the display unit 8002, which functions as a touch panel.

[0468] The housing 8001 has a mount with electrodes, and in addition to the viewfinder 8100, it can also be connected to, for example, a strobe device.

[0469] The viewfinder 8100 includes a housing 8101, a display unit 8102, and buttons 8103, etc.

[0470] The housing 8101 is attached to the camera 8000 by a mount that engages with the camera 8000's mount. The viewfinder 8100 can, for example, display the image received from the camera 8000 on the display unit 8102.

[0471] Button 8103 functions, for example, as a power button.

[0472] A display device according to one embodiment of the present invention can be applied to the display unit 8002 of the camera 8000 and the display unit 8102 of the viewfinder 8100. The camera 8000 may also have a built-in viewfinder.

[0473] Figure 32B shows the external appearance of the head-mounted display 8200.

[0474] The head-mounted display 8200 includes a mounting section 8201, lenses 8202, a main unit 8203, a display unit 8204, and a cable 8205, among other components. The mounting section 8201 also has a built-in battery 8206.

[0475] Cable 8205 supplies power from battery 8206 to main unit 8203. Main unit 8203 is equipped with, for example, a wireless receiver and can display received video information on display unit 8204. Main unit 8203 is also equipped with a camera and can use information about the user's eyeball or eyelid movements as an input means.

[0476] Furthermore, the attachment portion 8201 may be equipped with multiple electrodes at a position that touches the user, capable of detecting the current flowing in accordance with the user's eye movements. This allows the head-mounted display 8200 to have a function of recognizing the user's gaze. The head-mounted display 8200 may also have a function of monitoring the user's pulse rate based on the current flowing through the electrodes. The attachment portion 8201 may also be equipped with various sensors such as a temperature sensor, a pressure sensor, or an acceleration sensor. The head-mounted display 8200 may also have a function of displaying the user's biometric information on the display unit 8204, or a function of changing the image displayed on the display unit 8204 in accordance with the user's head movements.

[0477] A display device according to one aspect of the present invention can be applied to the display unit 8204.

[0478] Figures 32C to 32E show the external appearance of the head-mounted display 8300. The head-mounted display 8300 includes a housing 8301, a display unit 8302, a band-shaped fixing device 8304, and a pair of lenses 8305.

[0479] The user can view the display on the display unit 8302 through the lens 8305. It is preferable to position the display unit 8302 in a curved shape, as this allows the user to experience a greater sense of presence. Furthermore, by viewing different images displayed in different areas of the display unit 8302 through the lens 8305, it is possible to perform, for example, a three-dimensional display using parallax. Note that the configuration is not limited to having one display unit 8302; two display units 8302 may be provided, with one display unit for each of the user's eyes.

[0480] A display device according to one embodiment of the present invention can be applied to the display unit 8302. The display device according to one embodiment of the present invention can also achieve extremely high resolution. For example, even when the display is magnified and viewed using the lens 8305 as shown in Figure 32E, the pixels are difficult for the user to see. In other words, the display unit 8302 can be used to allow the user to view highly realistic images.

[0481] Figure 32F shows the external appearance of a goggle-type head-mounted display 8400. The head-mounted display 8400 has a pair of housings 8401, a mounting part 8402, and a cushioning member 8403. A display unit 8404 and a lens 8405 are provided inside each of the pair of housings 8401. By displaying different images on the pair of display units 8404, a three-dimensional display using parallax can be achieved.

[0482] The user can view the display unit 8404 through the lens 8405. The lens 8405 has a focus adjustment mechanism and its position can be adjusted according to the user's eyesight. The display unit 8404 is preferably square or a horizontally elongated rectangle. This can enhance the sense of realism.

[0483] The mounting portion 8402 is preferably adjustable to the size of the user's face and has plasticity and elasticity to prevent it from slipping off. Furthermore, it is preferable that a part of the mounting portion 8402 has a vibration mechanism that functions as a bone conduction earphone. This eliminates the need for separate earphones or speakers, allowing users to enjoy video and audio simply by wearing the device. The housing 8401 may also have a function to output audio data via wireless communication.

[0484] The mounting portion 8402 and the cushioning member 8403 are parts that come into contact with the user's face (forehead, cheeks, etc.). By ensuring that the cushioning member 8403 is in close contact with the user's face, light leakage can be prevented, thereby enhancing the sense of immersion. It is preferable to use a soft material for the cushioning member 8403 so that it adheres closely to the user's face when the user wears the head-mounted display 8400. For example, materials such as rubber, silicone rubber, urethane, or sponge can be used. Furthermore, if, for example, a sponge surface is covered with cloth or leather (genuine leather or synthetic leather), gaps are less likely to form between the user's face and the cushioning member 8403, effectively preventing light leakage. In addition, using such materials is preferable because, in addition to being pleasant to the touch, it prevents the user from feeling cold when worn in cold seasons, for example. It is preferable that the components that come into contact with the user's skin, such as the cushioning member 8403 and the mounting portion 8402, are removable, as this facilitates cleaning or replacement.

[0485] The electronic equipment shown in Figures 33A to 33F includes a housing 9000, a display unit 9001, a speaker 9003, operation keys 9005 (including a power switch or operation switch), connection terminals 9006, sensors 9007 (including functions for measuring force, displacement, position, velocity, acceleration, angular velocity, rotational speed, distance, light, liquid, magnetism, temperature, chemical substances, sound, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, gradient, vibration, odor, or infrared radiation), a microphone 9008, etc.

[0486] The electronic devices shown in Figures 33A to 33F have various functions. For example, they may have functions to display various information (still images, videos, and 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 by various software (programs), a wireless communication function, and a function to read and process programs or data recorded on a recording medium. However, the functions of electronic devices are not limited to these and can have various functions. Electronic devices may have multiple display units. Furthermore, electronic devices may have, for example, a camera to capture still images or videos and save them to a recording medium (external or built into the camera), and a function to display the captured images on a display unit.

[0487] A display device according to one embodiment of the present invention can be applied to the display unit 9001.

[0488] Details of the electronic equipment shown in Figures 33A to 33F will be explained below.

[0489] Figure 33A is a perspective view showing a personal digital assistant (PDA) 9101. The PDA 9101 can be used, for example, as a smartphone. The PDA 9101 may also be equipped with a speaker 9003, a connection terminal 9006, a sensor 9007, etc. The PDA 9101 can also display text and image information on multiple surfaces. Figure 33A shows an example where three icons 9050 are displayed. Information 9051, indicated by a dashed rectangle, can also be displayed on other surfaces of the display unit 9001. Examples of information 9051 include notifications of incoming emails, SNS messages, or phone calls, the subject of an email, for example, an SNS message, the sender's name, date and time, battery level, or signal strength. Alternatively, icons 9050 may be displayed where the information 9051 is displayed.

[0490] Figure 33B is a perspective view showing the personal digital assistant (PDA) 9102. The PDA 9102 has the function of displaying information on three or more sides of the display unit 9001. Here, an example is shown in which information 9052, information 9053, and information 9054 are displayed on different sides. For example, a user can check information 9053, which is displayed in a position that can be observed from above the PDA 9102, while the PDA 9102 is stored in the breast pocket of their clothing. The user can check the display without taking the PDA 9102 out of their pocket and decide, for example, whether or not to answer a call.

[0491] Figure 33C is a perspective view showing a wristwatch-type personal information terminal 9200. The personal information terminal 9200 can be used, for example, as a smartwatch (registered trademark). The display unit 9001 has a curved display surface, allowing it to display information along the curved surface. The personal information terminal 9200 can also be used for hands-free calls by communicating with, for example, a wireless communication headset. Furthermore, the personal information terminal 9200 can transmit data to other information terminals and be charged via a connection terminal 9006. Charging may be performed by wireless power supply.

[0492] Figures 33D to 33F are perspective views showing a foldable personal information terminal 9201. Figure 33D shows the personal information terminal 9201 in an unfolded state, Figure 33F shows it in a folded state, and Figure 33E shows a perspective view of the transition between Figures 33D and 33F. The personal information terminal 9201 offers excellent portability in its folded state and excellent readability of the display due to its seamless, wide display area in its unfolded state. The display unit 9001 of the personal information terminal 9201 is supported by three housings 9000 connected by a hinge 9055. For example, the display unit 9001 can be bent with a radius of curvature of 0.1 mm to 150 mm.

[0493] The configuration examples illustrated in this embodiment, and the corresponding drawings, etc., can be appropriately combined with other configuration examples or drawings, etc., at least in part. [Examples]

[0494] In this example, we will describe the results of preparing and evaluating a sample that has a light-emitting element.

[0495] Figures 34A, 34B, and 34C are cross-sectional views showing the configuration of a sample fabricated in this embodiment. Sample 200A, shown in Figure 34A, comprises an insulating layer 101a, an insulating layer 101b on the insulating layer 101a, a light-emitting element 110R on the insulating layer 101b, and a protective layer 121 on the light-emitting element 110R.

[0496] The light-emitting element 110R includes a pixel electrode 111Ra on the insulating layer 101b, a pixel electrode 111Rb on the pixel electrode 111Ra and on the insulating layer 101b, and an EL layer 112R on the pixel electrode 111Rb and on the insulating layer 101b. Sample 200A also includes a protective layer 131Ra on the insulating layer 101b, which has a region in contact with the side surface of the EL layer 112R, and a protective layer 131Rb on the protective layer 131Ra. Furthermore, sample 200A includes a common layer 114 on the EL layer 112R, the protective layer 131Ra, the protective layer 131Rb, and the insulating layer 101b, and a common electrode 115 on the common layer 114. A protective layer 121 is also provided on the common electrode 115. Here, the pixel electrode 111R shown in Embodiment 1 etc. is formed by the pixel electrode 111Ra and the pixel electrode 111Rb, and the protective layer 131R shown in Embodiment 1 etc. is formed by the protective layer 131Ra and the protective layer 131Rb.

[0497] Sample 200B, shown in Figure 34B, differs from sample 200A in that it does not have protective layers 131Ra and 131Rb. In sample 200B, the side surface of the EL layer 112R is in contact with the common layer 114.

[0498] Sample 200C, shown in Figure 34C, has an insulating layer 101a, an insulating layer 101b on the insulating layer 101a, a pixel electrode 111Ra on the insulating layer 101b, a pixel electrode 111Rb on the pixel electrode 111Ra, an EL layer 112R on the pixel electrode 111Rb, a common layer 114 on the EL layer 112R, a common electrode 115 on the common layer 114, and a protective layer 121 on the common electrode 115. Sample 200C differs from Sample 200B in that it is not patterned.

[0499] Figure 34D shows the configuration of the EL layer 112R. The EL layer 112 includes a hole injection layer 151, a hole transport layer 152 on the hole injection layer 151, an emissive layer 153 on the hole transport layer 152, a hole blocking layer 154 on the emissive layer 153, and an electron transport layer 155 on the hole blocking layer 154. Here, the emissive layer 153 has the function of emitting red light.

[0500] Figures 35A to 35E and 36A to 36D are cross-sectional views of each step in the method for preparing sample 200A in this embodiment.

[0501] In the preparation of sample 200A, first, a resin layer was formed as insulating layer 101a on a substrate (not shown) using a spin coating method. Next, a silicon nitride layer was formed on insulating layer 101a as insulating layer 101b using a CVD method.

[0502] Next, a silver-palladium-copper alloy film, which would later become the pixel electrode 111Ra, was deposited on the insulating layer 101b using a sputtering method to a thickness of 100 nm. Subsequently, a portion of the conductive film was removed by wet etching to form the pixel electrode 111Ra.

[0503] Next, an indium tin oxide film containing silicon, which would later become the pixel electrode 111Rb, was deposited on the pixel electrode 111Ra and the insulating layer 101b using a sputtering method to a thickness of 100 nm. Subsequently, a portion of the conductive film was removed by wet etching to form the pixel electrode 111Rb (Figure 35A).

[0504] Next, an EL film 112Rf, which would later become the EL layer 112R, was formed on the pixel electrode 111Rb and the insulating layer 101b using a vapor deposition method. The structure of the EL film 112Rf was as shown in Figure 34D, with the hole injection layer 151 having a thickness of 11.4 nm, the hole transport layer 152 having a thickness of 57.5 nm, the light-emitting layer 153 having a thickness of 74.4 nm, the hole blocking layer 154 having a thickness of 10 nm, and the electron transport layer 155 having a thickness of 10 nm.

[0505] Next, an aluminum oxide film was deposited on the EL film 112Rf using the ALD method to form a sacrificial film 144Ra, which would later become the sacrificial layer 145Ra, with a thickness of 30 nm. Subsequently, an indium tin oxide film was deposited on the sacrificial film 144Ra using the sputtering method to form a sacrificial film 144Rb, which would later become the sacrificial layer 145Rb, with a thickness of 50 nm.

[0506] Next, a resist was applied to the sacrificial film 144Rb, and a resist mask 143 was formed by exposure and development (Figure 35B).

[0507] Next, the portions of the sacrificial film 144Rb, sacrificial film 144Ra, and EL film 112Rf that were not covered by the resist mask 143 were removed by dry etching to form the sacrificial layer 145Rb, sacrificial layer 145Ra, and EL layer 112R. The resist mask 143 was also removed (Figure 35C).

[0508] Next, an aluminum oxide film, which would later become the protective layer 131Ra, was formed on the sacrificial layer 145Rb and the insulating layer 101b using the ALD method to a thickness of 15 nm. Subsequently, the EL film 112f was formed on the protective layer 131Raf using the vapor deposition method (Figure 35D).

[0509] Next, the EL film 112f was removed by dry etching (Figure 35E). Subsequently, a silicon nitride film was formed on the protective film 131Raf, which would later become the protective layer 131Rb, using a sputtering method to a thickness of 90 nm (Figure 36A).

[0510] Next, the protective film 131Rbf was processed by dry etching to form the protective layer 131Rb (Figure 36B). Then, the protective film 131Raf was processed by dry etching to form the protective layer 131Ra. After that, the sacrificial layer 145Rb and the sacrificial layer 145Ra were removed using wet etching (Figure 36C).

[0511] Next, as the common layer 114, a lithium fluoride film was formed on the EL layer 112R, the protective layer 131Ra, the protective layer 131Rb, and the insulating layer 101b using a vapor deposition method to a thickness of 1 nm. Then, a ytterbium film was formed on the lithium fluoride film using a vapor deposition method to a thickness of 1 nm. In other words, the common layer 114 was constructed as a laminated structure of a lithium fluoride film and a ytterbium film.

[0512] Next, as a common electrode 115, an alloy film with a silver-to-magnesium ratio of 10:1 was formed on the common layer 114 using a vapor deposition method to a thickness of 15 nm. This completed the formation of the light-emitting element 110R.

[0513] Next, an indium gallium zinc oxide film was formed on the common electrode 115 as a protective layer 121 using the sputtering method to a thickness of 70 nm (Figure 36D). Sample 200A was formed using the method described above.

[0514] Figures 37A to 37E are cross-sectional views of each step in the method for preparing sample 200B in this embodiment.

[0515] In preparing sample 200B, the same steps as those shown in Figures 35A, 35B, and 35C for preparing sample 200A were first performed (Figure 37A). Next, the EL film 112f was formed on the sacrificial layer 145Rb and the insulating layer 101b using a vapor deposition method (Figure 37B). In other words, unlike sample 200A, the protective film 131Raf was not formed.

[0516] Next, the EL film 112f was removed by dry etching (Figure 37C). Subsequently, the sacrificial layer 145Rb and the sacrificial layer 145Ra were removed (Figure 37D). In other words, unlike sample 200A, the protective film 131Rbf was not formed.

[0517] Subsequently, a common layer 114, a common electrode 115, and a protective layer 121 were formed in the same manner as in sample 200A (Figure 37E). Sample 200B was formed using the method described above.

[0518] In the preparation of sample 200C, first, a resin layer was formed on a substrate (not shown) as insulating layer 101a using a spin-coating method. Next, a silicon nitride layer was formed on insulating layer 101a as insulating layer 101b using a CVD method.

[0519] Next, a silver-palladium-copper alloy film was deposited on the insulating layer 101b as the pixel electrode 111Ra to a thickness of 100 nm using the sputtering method. Subsequently, an indium-tin oxide film containing silicon was deposited on the pixel electrode 111Ra as the pixel electrode 111Rb to a thickness of 100 nm using the sputtering method.

[0520] Next, the EL layer 112R was formed on the pixel electrode 111Rb using a vapor deposition method. The configuration of the EL layer 112R is as shown in Figure 34D, and the film thicknesses of the hole injection layer 151, hole transport layer 152, light-emitting layer 153, hole blocking layer 154, and electron transport layer 155 were the same as those of sample 200A and sample 200B.

[0521] Subsequently, a common layer 114, a common electrode 115, and a protective layer 121 were formed, similar to samples 200A and 200B. Sample 200C was then formed using the method described above. As described above, no sacrificial layer was formed and no patterning by etching of the EL film was performed during the formation of sample 200C. It can be said that the preparation of sample 200C was carried out entirely under vacuum.

[0522] Figure 38 is a graph showing the luminance-voltage characteristics of samples 200A, 200B, and 200C. Figure 39 is a graph showing the current efficiency-luminance characteristics of samples 200A, 200B, and 200C. Furthermore, the luminous intensity of each of the samples 200A, 200B, and 200C is 1000 cd / m². 2 Table 1 shows the characteristics of the light-emitting element 110R when it is in the vicinity.

[0523] [Table 1]

[0524] As shown in Figure 38, sample 200B required a higher voltage to achieve the same brightness compared to samples 200A and 200C. On the other hand, there was almost no difference between the brightness-voltage characteristics of sample 200A and sample 200C. In other words, despite being processed by dry etching of the EL film 112Rf, sample 200A had brightness-voltage characteristics equivalent to sample 200C, which was fabricated using a continuous vacuum process.

[0525] Furthermore, as shown in Figure 39, compared to sample 200C, which was fabricated using a continuous vacuum process, samples 200A and 200B, which were processed by dry etching of the EL film 112Rf, showed lower current efficiency at low brightness levels. However, it was confirmed that the decrease in current efficiency was suppressed in sample 200A compared to sample 200B.

[0526] Here, sample 200A differs from sample 200B in that, as shown in Figure 35C, a protective film 131Raf is provided to cover the side surface of the EL layer 112R, for example, before the deposition of the EL film 112f shown in Figures 35D and 35E, and before its removal by dry etching. It was suggested that by providing the protective film 131Raf, the degradation of the characteristics of the light-emitting element 110R caused by the deposition of the EL film 112f and its removal by dry etching can be suppressed.

[0527] Figure 40 is a graph showing the change in normalized luminance over time for samples 200A, 200B, and 200C. In Figure 40, the normalized luminance represents the relative luminance based on the luminance of the light-emitting element 110R at time 0, i.e., the start of luminance measurement. The normalized luminance shown in Figure 40 is calculated assuming an intrinsic luminance of 7900 cd / m² for the light-emitting element 110R. 2 The measurements were taken using a constant current at room temperature. Here, the graph showing the change in normalized brightness over time is called the reliability curve.

[0528] As shown in Figure 40, there was no significant difference in the slope of the reliability curve for sample 200A, sample 200B, and sample 200C. Therefore, it was confirmed that there was no significant difference in the reliability of sample 200A, sample 200B, and sample 200C.

[0529] As described above, by providing protective layers 131Ra and 131Rb, even when processing the EL film by dry etching, it was possible to manufacture a light-emitting element that has the same driving voltage and reliability as a light-emitting element manufactured using a vacuum process, and in which the decrease in current efficiency is suppressed compared to when protective layers 131Ra and 131Rb are not provided. [Explanation of Symbols]

[0530] 100: Display device, 100A: Display device, 100B: Display device, 100C: Display device, 100D: Display device, 100E: Display device, 100F: Display device, 101: Layer, 101a: Insulating layer, 101b: Insulating layer, 103: Pixel, 103a: Sub-pixel, 103b: Sub-pixel, 103c: Sub-pixel, 110: Light-emitting element, 110B: Light-emitting element, 110G: Light-emitting element, 110R: Light-emitting element, 111: Pixel electrode, 111B: Pixel electrode, 111C: Connecting electrode, 111G: Pixel electrode, 111R: Pixel electrode, 111Ra: Pixel electrode, 111Rb: Pixel electrode, 112: EL layer, 112B :EL layer, 112Bf:EL film, 112f:EL film, 112G:EL layer, 112Gf:EL film, 112R:EL layer, 112Rf:EL film, 114:common layer, 115:common electrode, 121:protective layer, 124a:pixel, 124b:pixel, 130:region, 131:protective layer, 131a:protective layer, 131b:protective layer, 131B:protective layer, 131Ba:protective layer, 131Baf:protective film, 131Bb:protective layer, 131Bbf:protective film, 131Bf:protective film, 131G:protective layer, 131Ga:protective layer, 131Gaf:protective film, 131Gb:protective layer, 131Gbf:protective film, 1 31Gf: protective film, 131R: protective layer, 131Ra: protective layer, 131Raf: protective film, 131Rb: protective layer, 131Rbf: protective film, 131Rf: protective film, 132: insulating layer, 132f: insulating film, 133: protective layer, 133f: protective film, 143: resist mask, 143a: resist mask, 143b: resist mask, 143c: resist mask, 144Ba: sacrificial film, 144Bb: sacrificial film, 144Ga: sacrificial film, 144Gb: sacrificial film, 144Ra: sacrificial film, 144Rb: sacrificial film, 145: sacrificial layer, 145a: sacrificial layer, 145b: sacrificial layer, 145Ba: sacrificial layer Layer, 145Bb: Sacrificial layer, 145G: Sacrificial layer, 145Ga: Sacrificial layer, 145Gb: Sacrificial layer, 145R: Sacrificial layer, 145Ra: Sacrificial layer, 145Rb: Sacrificial layer, 151: Hole injection layer, 152: Hole transport layer, 153: Light-emitting layer, 154: Hole blocking layer, 155: Electron transport layer, 160a: Region, 160b: Region, 200A: Sample, 200B: Sample, 200C: Sample, 201: Transistor, 204: Connector, 205: Transistor, 209: Transistor, 210: Transistor, 211: Insulating layer, 213: Insulating layer, 214: Insulating layer, 215: Insulating layer,218: insulating layer, 221: conductive layer, 222a: conductive layer, 222b: conductive layer, 223: conductive layer, 225: insulating layer, 228: region, 231: semiconductor layer, 231i: channel formation region, 231n: low resistance region, 240: capacitance, 241: conductive layer, 242: connection layer, 243: insulating layer, 245: conductive layer, 251: conductive layer, 252: conductive layer, 253: insulating layer, 254: insulating layer, 255: insulating layer, 256: plug, 261: insulating layer, 262: insulating layer, 263: insulating layer, 264: insulating layer, 265: insulating layer, 271: plug, 274: plug, 274a: conductive layer, 274b: conductive 280: Electrical layer, 281: Display module, 282: Display section, 283: Circuit section, 283a: Pixel circuit section, 284: Pixel section, 285: Terminal section, 286: Wiring section, 290: FPC, 291: Substrate, 292: Substrate, 301: Substrate, 301A: Substrate, 301B: Substrate, 310: Transistor, 310A: Transistor, 310B: Transistor, 311: Conductive layer, 312: Low resistance region, 313: Insulating layer, 314: Insulating layer, 315: Element isolation layer, 320: Transistor, 321: Semiconductor layer, 323: Insulating layer, 324: Conductive layer, 325: Conductive layer, 326: Insulation Layer, 327: conductive layer, 328: insulating layer, 329: insulating layer, 331: substrate, 332: insulating layer, 341: conductive layer, 342: conductive layer, 343: plug, 414: insulating layer, 417: light shielding layer, 418: conductive layer, 418B: conductive layer, 418G: conductive layer, 418R: conductive layer, 419: resin layer, 420: substrate, 442: adhesive layer, 443: space, 451: substrate, 452: substrate, 461: conductive layer, 462: display unit, 464: circuit, 465: wiring, 468: conductive layer, 472: FPC, 473: IC, 772: lower electrode, 785: layer, 786: EL layer, 786a: EL layer, 786b :EL layer, 788: upper electrode, 4411: light-emitting layer, 4412: light-emitting layer, 4413: light-emitting layer, 4420: layer, 4420-1: layer, 4420-2: layer, 4430: layer, 4430-1: layer, 4430-2: layer, 6500: electronic equipment, 6501: housing, 6502: display unit, 6503: power button, 6504: button, 6505: speaker, 6506: microphone, 6507: camera, 6508: light source, 6510: protective member, 6511: display panel, 6512: optical member, 6513: touch sensor panel, 6515: FPC, 6516: IC, 6517: printed circuit board,6518: Battery, 7000: Display unit, 7100: Television equipment, 7101: Housing, 7103: Stand, 7111: Remote control unit, 7200: Notebook personal computer, 7211: Housing, 7212: Keyboard, 7213: Pointing device, 7214: External connection port, 7300: Digital signage, 7301: Housing, 7303: Speaker, 7311: Information terminal, 7400: Digital signage, 7401: Pillar, 7411: Information terminal, 8000: Camera, 8001: Housing, 8002: Display unit, 8003: Operation buttons, 8004: Shutter button, 8006: Lens, 8100: Viewfinder, 8101: Housing, 8102: Display unit, 8103: Button, 8200: Head-mounted display, 8201: Mounted Attachment part, 8202: Lens, 8203: Main unit, 8204: Display unit, 8205: Cable, 8206: Battery, 8300: Head-mounted display, 8301: Housing, 8302: Display unit, 8304: Fixing device, 8305: Lens, 8400: Head-mounted display, 8401: Housing, 8402: Attachment part, 8403: Cushioning material, 8404: Display unit, 8405: Lens, 9000: Enclosure, 9001: Display unit, 9003: Speaker, 9005: Operation keys, 9006: Connection terminal, 9007: Sensor, 9008: Microphone, 9050: Icon, 9051: Information, 9052: Information, 9053: Information, 9054: Information, 9055: Hinge, 9101: Personal digital assistant, 9102: Personal digital assistant, 9200: Personal digital assistant, 9201: Personal digital assistant,

Claims

[Claim 1] A first pixel electrode and a second pixel electrode are formed on an insulating surface. A first EL film and a first sacrificial film are formed sequentially on the first pixel electrode and the second pixel electrode, By processing the first sacrificial film and the first EL film, a first sacrificial layer and a first EL layer are formed, respectively, having a region that overlaps with the first pixel electrode. A first protective film is formed that covers at least the sides of the first EL layer and the sides and top of the first sacrificial layer. By processing the first protective film, a first protective layer is formed having a region that overlaps with the side surface of the first EL layer. A second EL film and a second sacrificial film are formed sequentially on the first sacrificial layer and on the second pixel electrode, By processing the second sacrificial film and the second EL film, a second sacrificial layer and a second EL layer are formed, respectively, having a region that overlaps with the second pixel electrode. A second protective film is formed that covers at least the upper surface of the first sacrificial layer, the upper and side surfaces of the second sacrificial layer, the side surfaces of the first protective layer, and the side surfaces of the second EL layer. By processing the second protective film, a second protective layer is formed between the first protective layer and the insulating layer, and between the second EL layer and the insulating layer. A third protective film is formed on the first sacrificial layer, the second sacrificial layer, and the insulating layer. An insulating film is formed on the protective film 3 described above. By processing the insulating film, an insulating layer is formed between the first EL layer and the second EL layer. A third protective layer is formed by processing the aforementioned protective film 3. Remove the first sacrificial layer and the second sacrificial layer, A method for manufacturing a display device in which a common electrode is formed on the first EL layer, the second EL layer, and the third protective layer.

Images