Display device, display module, electronic device

Abstract

The present invention provides a display device which has high display quality and high reliability. This display device comprises: a first light-emitting element; a second light-emitting element which is arranged so as to be 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 the common electrode. The first EL layer is arranged on the first pixel electrode; and the second EL layer is arranged on the second pixel electrode. The first protective layer has a region that overlaps with a lateral surface of the first pixel electrode, a lateral surface of the second pixel electrode, a lateral surface of the first EL layer, and a lateral surface of the second EL layer. The insulating layer is arranged on the first protective layer; and the second protective layer is arranged on the insulating layer. The common electrode is arranged on the first EL layer, the second EL layer, and the second protective layer.

Description

Display device, display device manufacturing method, display module, and electronic device

[0001] BACKGROUND OF THE INVENTION 1. Field of the Invention One embodiment of the present invention relates to a display device and a manufacturing method thereof.

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

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

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

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

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

[0007] Patent Document 1: JP 2002-324673 A, International Publication No. 2018 / 087625

[0008] An object of one embodiment of the present invention is to provide a display device with high display quality.An object of one embodiment of the present invention is to provide a display device with high reliability.An object of one embodiment of the present invention is to provide a display device with low power consumption.An object of one embodiment of the present invention is to provide a display device that can easily achieve high definition.An object of one embodiment of the present invention is to provide a low-cost display device.An object of one embodiment of the present invention is to provide a display device that combines high display quality and high definition.An object of one embodiment of the present invention is to provide a display device with high contrast.An object of one embodiment of the present invention is to provide a display device having a novel structure.

[0009] An object of one embodiment of the present invention is to provide a manufacturing method for a display device with high display quality.An object of one embodiment of the present invention is to provide a manufacturing method for a highly reliable display device.An object of one embodiment of the present invention is to provide a manufacturing method for a display device with low power consumption.An object of one embodiment of the present invention is to provide a manufacturing method for a display device that can easily achieve high resolution.An object of one embodiment of the present invention is to provide a manufacturing method for a display device with low cost.An object of one embodiment of the present invention is to provide a manufacturing method for a display device that combines high display quality and high resolution.An object of one embodiment of the present invention is to provide a manufacturing method for a display device with high contrast.An object of one embodiment of the present invention is to provide a manufacturing method for a display device having a novel structure.

[0010] Note that the description of these problems does not preclude the existence of other problems. Note that one embodiment of the present invention does not necessarily solve all of these problems. Note that problems other than these can be extracted from the description of the specification, drawings, claims, etc.

[0011] One embodiment of the present invention is a display device including 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, in which the first light-emitting element has a first pixel electrode, a first EL layer, and a common electrode, and the second light-emitting element has a second pixel electrode, a second EL layer, and a common electrode, the first EL layer being provided over the first pixel electrode, the second EL layer being provided over the second pixel electrode, the first protective layer having a region overlapping with a side surface of the first pixel electrode, a side surface of the second pixel electrode, a side surface of the first EL layer, and a side surface of the second EL layer, the insulating layer being provided over the first protective layer, the second protective layer being provided over the insulating layer, and the common electrode being provided over the first EL layer, the second EL layer, and the second protective layer.

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

[0013] Alternatively, in the above aspect, the display device may have a third protective layer, and the third protective layer may have an area in contact with the side surface and the bottom surface of the first protective layer.

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

[0015] Alternatively, in the above aspect, the first protective layer may have an area in contact with the side surface and the bottom surface of the insulating layer, the second protective layer may have an area in contact with the top surface of the insulating layer, and the first protective layer and the second protective layer may contain a nitride.

[0016] Alternatively, in the above aspect, the first protective layer and the second protective layer may include at least one of silicon nitride, aluminum nitride, and hafnium nitride.

[0017] Alternatively, in the above aspect, the insulating layer may include an organic material.

[0018] Alternatively, in the above-described embodiment, a common layer may be provided between the first EL layer, the second EL layer, and 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, and 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 1 μm or less in an area.

[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 be 100 nm or less in a region.

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

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

[0023] Alternatively, one embodiment of the present invention provides a semiconductor device including: forming a first pixel electrode and a second pixel electrode over an insulating surface; forming a first EL film and a first sacrificial film in this order over the first pixel electrode and the second pixel electrode; processing the first sacrificial film and the first EL film to form a first sacrificial layer and a first EL layer, each having a region overlapping with the first pixel electrode; forming a first protective film that covers at least a side surface of the first EL layer and a side surface and a top surface of the first sacrificial layer; processing the first protective film to form a first protective layer having a region overlapping with the side surface of the first EL layer; forming a second EL film and a second sacrificial film in this order over the first sacrificial layer and the second pixel electrode; processing the second sacrificial film and the second EL film to form a second sacrificial layer and a second sacrificial film, each having a region overlapping with the second pixel electrode. a second EL layer and a second EL layer, respectively; forming a second protective film that covers at least an upper surface of the first sacrificial layer, an upper surface and side surfaces of the second sacrificial layer, a side surface of the first protective layer, and a side surface of the second EL layer; forming an insulating film on the second protective film and 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 second protective layers 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, the second sacrificial layer, and the insulating layer; processing the third protective film to form a third protective layer on the insulating layer; removing the first sacrificial layer and the second sacrificial layer; and forming a common electrode on the first EL layer, the second EL layer, and the third protective layer.

[0024] Alternatively, in the above aspect, after forming the first protective film, a fourth protective film may be formed so as to have an area in contact with the first protective film, and after forming the second protective film, a fifth protective film may be formed so as to have an area 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 by ALD, and the third to fifth protective films may be formed by sputtering or CVD.

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

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

[0028] Alternatively, in the above aspect, 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, a hole transport layer, a hole blocking layer, an electron blocking layer, an electron transport layer, and an electron injection layer may be formed as a common layer on the first EL layer, the second EL layer, and the insulating layer.

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

[0031] According to one embodiment of the present invention, a method for manufacturing a display device with high display quality can be provided. According to one embodiment of the present invention, a method for manufacturing a display device with high reliability can be provided. According to one embodiment of the present invention, a method for manufacturing a display device with low power consumption can be provided. According to one embodiment of the present invention, a method for manufacturing a display device that can easily achieve high resolution can be provided. According to one embodiment 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 embodiment of the present invention, a method for manufacturing a display device with low cost can be provided. According to one embodiment of the present invention, a method for manufacturing a display device with high contrast can be provided. According to one embodiment of the present invention, a method for manufacturing a display device having a novel structure can be provided.

[0032] Note that the description of these effects does not preclude the existence of other effects. Note that one embodiment of the present invention does not necessarily have all of these effects. Note that effects other than these can be extracted from the description in the specification, drawings, claims, etc.

[0033] FIG. 1 is a top view showing a structural example of a display device. FIGS. 2A, 2B, 2C1, 2C2, and 2D are cross-sectional views showing a structural example of a display device. FIGS. 3A and 3B are cross-sectional views showing a structural example of a display device. FIGS. 4A to 4F are top views showing a structural example of a pixel. FIGS. 5A to 5E are top views showing a structural example of a pixel. FIGS. 6A to 6D are cross-sectional views showing an example of a manufacturing method of a display device. FIGS. 7A1, 7A2, 7B1, and 7B2 are cross-sectional views showing an example of a manufacturing method of a display device. FIGS. 8A to 8C are cross-sectional views showing an example of a manufacturing method of a display device. FIGS. 9A1, 9A2, 9B1, and 9B2 are cross-sectional views showing an example of a manufacturing method of a display device. FIGS. 10A to 10C are cross-sectional views showing an example of a manufacturing method of a display device. FIGS. 11A to 11C are cross-sectional views showing an example of a manufacturing method of a display device. FIGS. 12A, 12B1, and 12B2 are cross-sectional views illustrating an example of a method for manufacturing a display device. FIGS. 13A and 13B are cross-sectional views illustrating an example of a method for manufacturing a display device. FIGS. 14A, 14B1, and 14B2 are cross-sectional views illustrating an example of a method for manufacturing a display device. FIGS. 15A, 15B1, and 15B2 are cross-sectional views illustrating an example of a method for manufacturing a display device. FIGS. 16A and 16B are cross-sectional views illustrating an example of a method for manufacturing a display device. FIGS. 17A to 17D are cross-sectional views illustrating an example of a configuration of a display device. FIGS. 18A to 18D are cross-sectional views illustrating an example of a configuration of a display device. FIGS. 19A to 19D are cross-sectional views illustrating an example of a configuration of a display device. FIGS. 20A to 20D are cross-sectional views illustrating an example of a configuration of a display device. FIG. 21 is a perspective view illustrating an example of a configuration of a display device. FIG. 22A is a cross-sectional view illustrating an example of a configuration of a display device. FIGS. 22B and 22C are cross-sectional views illustrating an example of a configuration of a transistor. FIG. 23 is a cross-sectional view illustrating an example of a configuration of a display device. Fig. 24A and Fig. 24B are perspective views showing an example of the configuration of a display module. Fig. 25 is a cross-sectional view showing an example of the configuration of a display device. Fig. 26 is a cross-sectional view showing an example of the configuration of a display device. Fig. 27 is a cross-sectional view showing an example of the configuration of a display device. Fig. 28 is a cross-sectional view showing an example of the configuration of a display device. Figs. 29A to 29F are diagrams showing an example of the configuration of a light-emitting element. Figs. 30A and 30B are diagrams showing an example of an electronic device. Figs. 31A to 31D are diagrams showing an example of an electronic device.32A to 32F are diagrams showing an example of an electronic device. FIGS. 33A to 33F are diagrams showing an example of an electronic device. FIGS. 34A to 34C are cross-sectional views showing the configuration of a sample according to an example. FIG. 34D is a diagram showing the configuration of an EL layer. FIGS. 35A to 35E are cross-sectional views showing a method for fabricating a sample according to an example. FIGS. 36A to 36D are cross-sectional views showing a method for fabricating a sample according to an example. FIGS. 37A to 37E are cross-sectional views showing a method for fabricating a sample according to an example. FIG. 38 is a graph showing the luminance-voltage characteristics of a sample according to an example. FIG. 39 is a graph showing the current efficiency-luminance characteristics of a sample according to an example. FIG. 40 is a graph showing the change over time in normalized luminance of a sample according to an example.

[0034] Hereinafter, embodiments will be described with reference to the drawings. However, it will be readily understood by those skilled in the art that the embodiments can be implemented in many different ways and that various changes in form and details can be made without departing from the spirit and scope of the present invention. Therefore, the present invention should not be interpreted as being limited to the following description of the embodiments.

[0035] In the configuration of the invention described below, the same parts or parts having similar functions are denoted by the same reference numerals in different drawings, and repeated explanations thereof will be omitted. In addition, when referring to similar functions, the same hatch pattern may be used and no particular reference numeral may be assigned.

[0036] In the drawings described in this specification, the size of each component, the thickness of a layer, or an area may be exaggerated for clarity, and therefore, the drawings are not necessarily limited to the scale.

[0037] In this specification, ordinal numbers such as "first" and "second" are used to avoid confusion of components and do not limit the number.

[0038] Furthermore, in this specification and the like, the terms "film" and "layer" can be interchangeable in some cases or depending on the situation. For example, the terms "conductive layer" and "insulating layer" can sometimes be interchangeable with the terms "conductive film" and "insulating film."

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

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

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

[0042] Embodiment 1 In this embodiment, a structural example of a display device according to one embodiment of the present invention and an example of a manufacturing method of the display device will be described.

[0043] One embodiment of the present invention is a display device having a light-emitting element (also referred to as a light-emitting device). The display device has at least two light-emitting elements that emit light of different colors. Each light-emitting element has a pair of electrodes and an EL layer therebetween. As the light-emitting element, an electroluminescent element such as an organic EL element or an inorganic EL element can be used. Alternatively, a light-emitting diode (LED) can be used. The light-emitting element of one embodiment of the present invention is preferably an organic EL element (organic electroluminescent element). Two or more light-emitting elements that emit light of 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] Here, when creating separate EL layers for light-emitting elements of different colors, it is known to form the EL layers by vapor deposition using a shadow mask such as a metal mask. However, this method makes it difficult to achieve high resolution and a high aperture ratio because the shape and position of the island-shaped organic film can deviate from the design due to various factors, such as the accuracy of the metal mask, misalignment between the metal mask and the substrate, deflection of the metal mask, and, for example, the spread of the contours of the deposited film due to vapor scattering. Furthermore, during vapor deposition, debris may be generated due to material adhering to the metal mask. Such debris may cause pattern defects in the light-emitting elements. Furthermore, the debris may cause short circuits. Furthermore, a process of cleaning the material adhering to the metal mask is required. Therefore, measures have been taken to artificially increase the resolution (also known as pixel density) by applying special pixel arrangement methods, such as a pentile arrangement.

[0045] In one embodiment of the present invention, an EL layer is processed into a fine pattern without using a shadow mask such as a metal mask. This makes it possible to realize a display device with high definition and a large aperture ratio, which have been difficult to achieve until now. Furthermore, because the EL layer can be individually fabricated, a display device with extremely vivid, high contrast, and high display quality can be realized.

[0046] In this specification etc., a device fabricated using a metal mask or an FMM (fine metal mask, high-resolution metal mask) may be referred to as a device with an MM (metal mask) structure. Also, in this specification etc., a device fabricated without using a metal mask or an FMM may be referred to as a device with an MML (metal maskless) structure.

[0047] For simplicity, a case where two light-emitting elements (a first light-emitting element and a second light-emitting element) are separately formed will be described here. 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, in that order, on the first pixel electrode and the second pixel electrode. Next, a resist mask is formed on the first sacrificial film. Next, 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, having regions overlapping with the first pixel electrode. Note that in this specification and the like, 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 to cover the side surfaces of the first EL layer, the side surfaces and top surface of the first sacrificial layer, and the side surfaces and top surface of the second pixel electrode. The first protective film is then processed to form a first protective layer having an area overlapping the side surfaces 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 in this order on the first sacrificial layer and the second pixel electrode. Next, a resist mask is formed on the second sacrificial film. Next, the second sacrificial film and the second EL film are processed using the resist mask to form the second sacrificial layer and the second EL layer, respectively, having an area overlapping with the second pixel electrode.

[0050] Subsequently, a second protective film is formed to cover the upper and side surfaces 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.

[0051] Next, an insulating film is formed on the second protective film. Then, the insulating film is processed to form an insulating layer between the first EL layer and the second EL layer. A photosensitive material, such as a photosensitive resin, can be used for the insulating film. 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] Subsequently, the second protective film is processed to form second protective layers 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 by anisotropic etching 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, and then 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, a common electrode is formed on the first EL layer, the second EL layer, and the third protective layer, thereby forming two-color light-emitting elements. 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 formed.

[0055] Furthermore, after forming the first protective layer, by repeating the process from forming the first EL film to forming the first protective layer, it is possible to create light-emitting elements of three or more colors, and a display device having light-emitting elements of three or four or more colors can be realized.

[0056] As described above, in the display device of one embodiment of the present invention, an insulating layer is provided between the first EL layer and the second EL layer. The insulating layer can fill the gap between the first light-emitting element and the second light-emitting element. Therefore, the unevenness of the surface on which the common electrode is provided can be reduced, thereby suppressing the disconnection (step disconnection) of the common electrode. As described above, the display device of one embodiment of the present invention can be a highly reliable display device.

[0057] When an organic insulating material such as a photosensitive resin is used as the insulating layer between the first EL layer and the second EL layer, the insulating layer may contain oxygen, water, or the like. The penetration of oxygen, water, or the like into the EL layer may cause deterioration of a light-emitting element having the EL layer. Therefore, in a display device according to one embodiment of the present invention, a protective layer having a high barrier property against oxygen, water, or the like is provided to surround the insulating layer between the first EL layer and the second EL layer. This can prevent impurities such as oxygen and water from penetrating into the EL layer. Therefore, the display device according to one embodiment of the present invention can be a highly reliable display device. In the above example, a second protective layer is provided to cover the side and bottom surfaces of the insulating layer between the first EL layer and the second EL layer, and a third protective layer is provided to cover the top surface of the insulating layer. This allows the insulating layer between the first EL layer and the second EL layer to be surrounded by the second protective layer and the third protective layer. For example, an inorganic insulating material, such as an inorganic nitride film, can be used as a protective layer having high barrier properties against oxygen, water, etc. As the inorganic nitride, for example, 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 have a stacked structure of two or more layers. For example, the first protective film and the second protective film can have a two-layer stacked structure formed by depositing a first layer by a method with high coverage and a second layer by a method with low coverage. For example, the first protective film and the second protective film can have a two-layer stacked structure formed by depositing a first layer by an ALD method and depositing a second layer by a sputtering method or a chemical vapor deposition (CVD) method. This allows the first protective layer and the second protective layer to be thickened while covering steps, thereby suitably suppressing the intrusion of impurities such as oxygen and water into the first EL layer and the second EL layer. Therefore, the display device of one embodiment of the present invention can be a highly reliable display device.

[0059] As described above, it is preferable to prevent impurities from penetrating into the EL layer from the viewpoint of the reliability of the display device. However, if impurities adhere to the surface of the EL layer, the impurities may penetrate into the EL layer, thereby reducing the reliability of the display device. Therefore, it is preferable to remove impurities adhering to the surface of the first EL layer after forming the first EL layer and before forming the first protective film covering the first EL layer, thereby improving the reliability of the display device. Similarly, it is preferable to remove impurities adhering to the surface of the second EL layer after forming the second EL layer and before forming the second protective film covering the second EL layer. For example, placing the substrate on which the first EL layer is formed under an inert gas atmosphere can remove impurities adhering to the surface of the first EL layer. Furthermore, placing the substrate on which the second EL layer is formed under an inert gas atmosphere can remove impurities adhering to the surface of the second EL layer. The inert gas can be, for example, one or more selected from Group 18 elements (typically, helium, neon, argon, xenon, krypton, etc.) and nitrogen.

[0060] Furthermore, when the EL layer is exposed to air, impurities such as oxygen and water contained in the air may penetrate into the EL layer. After the first EL layer is formed, the surface of the first EL layer remains 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 allows the first protective film covering the first EL layer to be formed without exposing the first EL layer to air after processing the first EL film to form it. 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. This prevents impurities contained in air from penetrating into the EL layer, thereby improving the reliability of the display device. It is also preferable to perform other processes in the same apparatus, since this prevents components of the display device from coming into contact with air during the display device manufacturing process and increases the throughput of the display device manufacturing process.

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

[0062] Furthermore, the pattern of the EL layer itself can be made much smaller than when a metal mask is used. Furthermore, for example, when a metal mask is used to separately form an EL layer, thickness variations occur between the center and edges of the pattern, resulting in a smaller effective area that can be used as the light-emitting region relative to the overall area of ​​the pattern. On the other hand, with the above-described fabrication method, a pattern is formed by processing a film deposited to a uniform thickness, making it possible to achieve a uniform thickness within the pattern, and even with a fine pattern, almost the entire area can be used as the light-emitting region. Therefore, the above-described fabrication method can achieve both high definition and a high aperture ratio.

[0063] As described above, the above-described manufacturing method can realize a display device integrating minute light-emitting elements, and therefore, it is not necessary to artificially increase the resolution by applying a special pixel arrangement method such as a pen tile method, etc. Therefore, it is possible to realize a display device with a so-called stripe arrangement in which R, G, and B are arranged in one direction, and with a resolution of 500 ppi or more, 1000 ppi or more, 2000 ppi or more, further 3000 ppi or more, or even 5000 ppi or more.

[0064] Below, a more specific example of a structure and an example of a manufacturing method of a display device of one embodiment of the present invention will be described with reference to the drawings.

[0065] 1 shows a top view of a display device 100 according to one embodiment of the present invention. The display device 100 includes a plurality of light-emitting elements 110R that emit red light, a plurality of light-emitting elements 110G that emit green light, and a plurality of light-emitting elements 110B that emit blue light. In FIG. 1, the light-emitting regions of the light-emitting elements are labeled with R, G, and B to easily distinguish the light-emitting elements from one another.

[0066] In this specification and the like, for example, the light-emitting element 110R, the light-emitting element 110G, and the light-emitting element 110B may be collectively referred to as the light-emitting element 110. For example, the term "light-emitting element 110" refers to some or all of the light-emitting element 110R, the light-emitting element 110G, and the light-emitting element 110B. Similar descriptions are used for other elements.

[0067] The light-emitting elements 110R, 110G, and 110B are arranged in a matrix. The pixel 103 shown in Fig. 1 has a so-called stripe arrangement in which light-emitting elements of the same color are arranged in one direction. Note that the arrangement of the light-emitting elements is not limited to this, and arrangements such as a delta arrangement or a zigzag arrangement may also be used, or a pentile arrangement may also be used.

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

[0069] FIG. 1 also shows the connection electrode 111C and the common electrode 115, with the common electrode 115 indicated by a dashed line. The connection electrode 111C is provided with a potential (e.g., an anode potential or a cathode potential) to be supplied to the common electrode 115. The connection electrode 111C is provided, for example, outside the display area in which the light-emitting elements 110R are arranged. For example, the connection electrode 111C can be provided along the periphery of the display area. For example, the connection electrode 111C can be provided along one side of the periphery of the display area, or along two or more sides of the periphery of the display area. In other words, when the top surface of the display area is rectangular, the top surface of the connection electrode 111C can be strip-shaped, L-shaped, U-shaped (square bracket-shaped), frame-shaped, or the like.

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

[0071] 2A shows an example of a cross-sectional structure of the light-emitting element 110R, the light-emitting element 110G, and the light-emitting element 110B. Also, FIG. 2B shows an example of a cross-sectional structure of the light-emitting element 110G. The light-emitting element 110R is provided over a layer 101 including a transistor. Furthermore, the layer 101 including a transistor is provided over a substrate (not shown).

[0072] The transistor-containing layer 101 may have, for example, a stacked structure in which a plurality of transistors are provided and an insulating layer is provided to cover these transistors. As shown in Figures 2A and 2B, the transistor-containing layer 101 may have a recess between adjacent light-emitting elements 110. For example, a recess may be provided in an insulating layer located on the outermost surface of the transistor-containing layer 101. Note that the transistor-containing layer 101 may not have a recess between adjacent light-emitting elements 110.

[0073] The layer 101 including the transistor preferably includes, for example, a pixel circuit, a scanning line driver circuit (gate driver), a signal line driver circuit (source driver), etc. In addition to the above, an arithmetic circuit, a memory circuit, etc. may also be included.

[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. The light-emitting elements 110R, 110G, and 110B also have a common layer 114 on the EL layer 112R, 112G, and 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] The EL layer 112R, the EL layer 112G, and the EL layer 112B each have a light-emitting layer. The light-emitting layer is a layer containing a light-emitting substance. The light-emitting layer can contain one or more types of light-emitting substances. As the light-emitting substance, a substance that emits light of a color such as blue, purple, blue-purple, green, yellow-green, yellow, orange, or red is appropriately used. Furthermore, a substance that emits near-infrared light can also be used as the light-emitting substance. For example, the light-emitting layer of the EL layer 112R can contain a light-emitting substance that emits red light. Furthermore, the light-emitting layer of the EL layer 112G can contain a light-emitting substance that emits green light. Furthermore, the light-emitting layer of the EL layer 112B can contain a light-emitting substance that emits blue light.

[0076] Examples of the light-emitting material include fluorescent materials, phosphorescent materials, TADF materials, and quantum dot materials.

[0077] The quantum dot material may be a colloidal quantum dot material, an alloy quantum dot material, a core-shell quantum dot material, or a core quantum dot material. Materials containing elements from groups 12 and 16, 13 and 15, or 14 and 16 may also be used. 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 (particularly iridium complexes) having a 4H-triazole skeleton, a 1H-triazole skeleton, an imidazole skeleton, a pyrimidine skeleton, a pyrazine skeleton, or a pyridine skeleton; organometallic complexes (particularly iridium complexes) having a phenylpyridine derivative having an electron-withdrawing group as a ligand; platinum complexes; and rare earth metal complexes.

[0080] The light-emitting layer may contain one or more organic compounds (host materials, assist materials, etc.) in addition to a light-emitting substance (guest material). As the one or more organic compounds, one or both of a hole-transporting material and an electron-transporting material can be used. Furthermore, as the one or more organic compounds, a bipolar material or a TADF material can be used.

[0081] The light-emitting layer preferably includes, for example, a phosphorescent material and a hole-transporting material and an electron-transporting material that are a combination that easily forms an exciplex. This configuration allows for efficient emission using Exciplex-Triple Energy Transfer (ExTET), which is energy transfer from the exciplex to the light-emitting material (phosphorescent material). By selecting a combination that forms an exciplex that emits light that overlaps with the wavelength of the lowest-energy absorption band of the light-emitting material, the energy transfer becomes smooth and light emission can be achieved efficiently. This configuration allows for high efficiency, low-voltage operation, and a long lifetime of the light-emitting element to be achieved simultaneously.

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

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

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

[0085] Each of the EL layers 112R, 112G, and 112B preferably includes a light-emitting layer and a carrier transport layer on the light-emitting layer. This prevents the light-emitting layer from being exposed to the outermost surface during the manufacturing process of the display device 100, thereby reducing damage to the light-emitting layer. This improves the reliability of the light-emitting element. Therefore, the display device 100 can be 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 contains a material with high hole injection properties, such as an aromatic amine compound and a composite material containing a hole transport material and an acceptor material (electron acceptor material).

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

[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 that contains an electron transporting material. The electron transporting material is a material having a concentration of 1×10 −６ cm ２A substance having an electron mobility of 1 / Vs or more is preferred. As the electron-transporting material, a metal complex having a quinoline skeleton, a metal complex having a benzoquinoline skeleton, a metal complex having an oxazole skeleton, or a metal complex having a thiazole skeleton, as well as a material having high electron transport properties such as an oxadiazole derivative, a triazole derivative, an imidazole derivative, an oxazole derivative, a thiazole derivative, a phenanthroline derivative, a quinoline derivative having a quinoline ligand, a benzoquinoline derivative, a quinoxaline derivative, a dibenzoquinoxaline derivative, a pyridine derivative, a bipyridine derivative, a pyrimidine derivative, or a π-electron-deficient heteroaromatic compound including a nitrogen-containing heteroaromatic compound, can be used. Note that other materials can also be used as long as they have a higher electron-transporting property than a hole-transporting property.

[0089] The electron injection layer is a layer that injects electrons from the cathode to the electron transport layer and contains a material with high electron injection properties. Examples of the material with high electron injection properties include alkali metals, alkaline earth metals, and compounds thereof. Examples of the material with high electron injection properties include a composite material containing an electron transport material and a donor material (electron donor material).

[0090] The electron injection layer may be formed of, for example, lithium, cesium, ytterbium, lithium fluoride (LiF), cesium fluoride (CsF), calcium fluoride (CaF ｘ , where X is an arbitrary number), 8-(quinolinolato)lithium (abbreviation: Liq), 2-(2-pyridyl)phenolatolithium (abbreviation: LiPP), 2-(2-pyridyl)-3-pyridinolatolithium (abbreviation: LiPPy), 4-phenyl-2-(2-pyridyl)phenolatolithium (abbreviation: LiPPP), lithium oxide (LiO ｘ For example, an alkali metal, an alkaline earth metal, such as lithium fluoride, or cesium carbonate, or a compound thereof can be used. The electron injection layer may have a stacked structure of two or more layers. For example, the stacked structure may have a structure in which lithium fluoride is used in the first layer and ytterbium is provided in the second layer.

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

[0092] The organic compound having an unshared electron pair preferably has a lowest unoccupied molecular orbital (LUMO) of -3.6 eV to -2.3 eV. Generally, the highest occupied molecular orbital (HOMO) level and the LUMO level of an organic compound can be estimated by cyclic voltammetry (CV), photoelectron spectroscopy, optical absorption spectroscopy, inverse photoelectron spectroscopy, or the like.

[0093] For example, 4,7-diphenyl-1,10-phenanthroline (abbreviation: BPhen), 2,9-bis(naphthalen-2-yl)-4,7-diphenyl-1,10-phenanthroline (abbreviation: NBPhen), diquinoxalino[2,3-a:2',3'-c]phenazine (abbreviation: HATNA), or 2,4,6-tris[3'-(pyridin-3-yl)biphenyl-3-yl]-1,3,5-triazine (abbreviation: TmPPPyTz) can be used as the organic compound having an unshared electron pair. Note that NBPhen has a higher glass transition point (Tg) and is superior in heat resistance compared to BPhen.

[0094] The common layer 114 is preferably a layer having one or more 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. For example, in a light-emitting element in which the pixel electrode 111 serves as an anode and the common electrode serves as a cathode, the common layer 114 may have an electron injection layer or a structure having both an electron injection layer and an electron transport layer. Furthermore, in a light-emitting element in which the pixel electrode 111 serves as a cathode and the common electrode serves as an anode, the common layer 114 may have a hole injection layer or a structure having 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 layers 112R, 112G, and 112B may not have electron injection layers. For example, the EL layer 112R, the EL layer 112G, and the EL layer 112B may have a hole injection layer, a hole transport layer on the hole injection layer, a light emitting layer on the hole transport layer, and an electron transport layer on the light emitting layer. Furthermore, for example, if the common layer 114 has a hole injection layer, the EL layer 112R, the EL layer 112G, and the EL layer 112B may not have a hole injection layer.

[0095] As described 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, for example, etching. Therefore, by configuring the display device 100 to have the common layer 114, the manufacturing process of the display device 100 can be simplified, and the manufacturing cost of the display device 100 can be reduced. Therefore, the display device 100 can be a low-cost display device.

[0096] Furthermore, the common layer 114 and the common electrode 115 can be formed continuously without any intervening process such as etching. This allows the interface between the common layer 114 and the common electrode 115 to be a clean surface. This allows the display device 100 to be a highly reliable display device. The display device 100 does not need to have the common layer 114. In this case, for example, in a light-emitting element in which the pixel electrode 111 serves as an anode and the common electrode serves as a cathode, the EL layer 112R, the EL layer 112G, and the EL layer 112B can be configured such that an electron injection layer is provided on an electron transport layer.

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

[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, tantalum nitride, or the like can be used for the pixel electrode 111. Furthermore, an alloy can be used for the pixel electrode 111. For example, an alloy containing silver can be used. For example, an alloy containing silver can be used, such as an alloy containing silver, palladium, and copper. Furthermore, for example, an alloy containing aluminum can be used. Furthermore, two or more layers of these materials may be stacked.

[0099] The pixel electrode 111 may have a stacked structure in which a conductive layer that is reflective to visible light is provided over a conductive layer that is transparent to visible light. Examples of conductive materials that are transparent to visible light include conductive oxides such as indium oxide, indium tin oxide, indium zinc oxide, zinc oxide, zinc oxide containing gallium, indium tin oxide containing silicon, and indium zinc oxide containing silicon. 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. The oxide may be formed, for example, by oxidizing the surface of a conductive material that is reflective to visible light. Specifically, titanium oxide may be used. Titanium oxide may be formed, for example, by oxidizing the surface of titanium.

[0100] By providing an oxide on the surface of the pixel electrode 111, for example, an oxidation reaction with the pixel electrode 111 can be suppressed when the EL layer 112 is formed.

[0101] Furthermore, by forming the pixel electrode 111 in a stacked structure in which a conductive layer that is transparent to visible light is provided 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 providing the optical adjustment layer in the pixel electrode 111. The optical path length in the light-emitting element 110 corresponds to, for example, the sum of the thickness of the optical adjustment layer and the thickness of the layer provided below the layer containing the light-emitting compound in the EL layer 112.

[0103] In the light-emitting element 110, by varying the optical path length using a microcavity structure (a microresonator structure), it is possible to intensify light of a specific wavelength, thereby realizing 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 example, the EL layer 112R of the light-emitting element 110R that emits light with the longest wavelength can be the thickest, and the EL layer 112B of the light-emitting element 110B that emits light with the shortest wavelength can be the thinnest. However, this is not limitative, and the thickness of each EL layer 112 can be adjusted taking into consideration the wavelength of light emitted by each light-emitting element 110, the optical characteristics of the layers that make up the light-emitting element 110, the electrical characteristics of the light-emitting element 110, etc.

[0105] For the conductive layer having reflectivity to visible light, it is preferable to use aluminum, silver, or the like, which have high reflectivity. In particular, aluminum is suitable for manufacturing a high-definition display device because it is easy to microfabricate.

[0106] A transparent conductive oxide material is preferably used for the conductive layer that is transparent to visible light. However, if a transparent conductive oxide 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 contact the transparent conductive oxide film containing indium. For example, the pixel electrode 111 can have a three-layer stack structure including a layer using aluminum, a layer using titanium oxide, and a layer using indium tin oxide containing silicon.

[0107] Here, when forming the pixel electrode 111, it is preferable to successively form an aluminum film and a titanium oxide film. If the aluminum film is formed and then exposed to the atmosphere before forming the titanium oxide film, the aluminum film may be naturally oxidized due to exposure to the atmosphere. By forming the aluminum film and then the titanium oxide film without exposing it to the atmosphere, oxidation of the aluminum can be suppressed.

[0108] If the aluminum film needs to be exposed to the atmosphere before the titanium oxide film is formed after it has been formed, it is preferable to form another film on the aluminum film before exposing it to the atmosphere. This prevents the aluminum film from being oxidized by 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 the film may be exposed to the atmosphere before the titanium oxide film is formed on the titanium film.

[0109] Alternatively, if there is a concern that the surface of the aluminum film may be oxidized, the oxide film on the surface of the aluminum film may be removed by reverse sputtering. For example, after forming an aluminum film and exposing it to the atmosphere, 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). 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 a film in contact with the aluminum film without using oxygen gas. Therefore, it is preferable to form a titanium oxide film by sputtering using a titanium oxide target and an inert gas (e.g., argon gas).

[0111] The common electrode 115 can be a conductive layer that transmits visible light. For example, the common electrode 115 can be made of a conductive oxide such as indium oxide, indium tin oxide, indium zinc oxide, zinc oxide, or zinc oxide containing gallium, or graphene. Alternatively, the common electrode 115 can be made of a metal material such as gold, silver, platinum, magnesium, nickel, tungsten, chromium, molybdenum, iron, cobalt, copper, palladium, or titanium, or an alloy material containing such a metal material. Alternatively, the common electrode 115 can be made of a nitride of such a metal material (e.g., titanium nitride). Note that when a metal material or an alloy material (or a nitride thereof) is used, it is preferable to make the thickness thin enough to have light-transmitting properties. Alternatively, a stacked film of the above materials can be used as the conductive layer. For example, using a stacked film of an alloy of silver and magnesium and indium tin oxide for the common electrode 115 is preferable because the conductivity of the common electrode 115 can be increased.

[0112] Here, for example, between the EL layer 112R and the EL layer 112G, a protective layer 131 having an area overlapping with a side surface of the EL layer 112R and a protective layer 131 having an area overlapping with a side surface of the EL layer 112G are provided. Similar protective layers 131 are provided between the other EL layers 112. Furthermore, a protective layer 131 having an area overlapping with a side surface of the pixel electrode 111 can be provided.

[0113] The protective layer 131 is preferably a layer having a high barrier property against oxygen, water, and the like. This can prevent impurities such as oxygen and water from entering the inside from the side surface of the EL layer 112. This can prevent deterioration of the light-emitting element 110 and make the display device 100 a highly reliable display device.

[0114] The protective layer 131 can be made of an inorganic insulating material, for example, a layer containing an oxide or nitride such as silicon oxide, silicon oxynitride, silicon nitride oxide, silicon nitride, aluminum oxide, aluminum oxynitride, or hafnium oxide. Note that the protective layer 131 is preferably made of a film type and has a film thickness that does not have pinholes.

[0115] In this specification and the like, an oxynitride refers to a material whose composition contains more oxygen than nitrogen, and a nitride oxide refers to a material whose composition contains more nitrogen than oxygen. For example, silicon oxynitride refers to a material whose composition contains more oxygen than nitrogen, and silicon nitride oxide refers to a material whose composition contains more nitrogen than oxygen.

[0116] 2A and 2B show an example in which the top surface of the protective layer 131, which has a region overlapping with a side surface of the EL layer 112, is located higher than the top surface of the EL layer 112; however, one embodiment of the present invention is not limited to this. For example, the height of the top surface of the protective layer 131, which has a region overlapping with a side surface of the EL layer 112, may be equal to the height of the top surface of the EL layer 112. Alternatively, the top surface of the protective layer 131, which has a region overlapping with a side surface of the EL layer 112, may be located lower than the top surface of the EL layer 112.

[0117] Here, increasing the distance between adjacent EL layers 112 may reduce the aperture ratio of the pixel 103. On the other hand, decreasing the distance between adjacent EL layers 112 may prevent the protective layer 131 from covering the side surfaces of the EL layers 112, thereby reducing the barrier effect of the protective layer 131 and potentially allowing impurities to easily penetrate into the EL layers 112 from the side surfaces. Therefore, the distance between the side surface of one EL layer 112 and the side surface of an adjacent EL layer 112 preferably has a region of 3 nm to 200 nm, more preferably a region of 3 nm to 150 nm, even more preferably a region of 5 nm to 150 nm, still more preferably a region of 5 nm to 100 nm, even more preferably a region of 10 nm to 100 nm, and still more preferably a region of 10 nm to 50 nm. By setting the distance between the side surface of one EL layer 112 and the side surface of an adjacent EL layer 112 within the above-described range, the display device 100 can be 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 the EL layers 112 of the light-emitting elements 110. The insulating layer 132 is provided, for example, between two EL layers 112 that exhibit different colors. Alternatively, the insulating layer 132 is provided, for example, 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 the pixel electrodes 111 of the light-emitting elements 110.

[0119] The insulating layer 132 is disposed between the EL layers 112 of adjacent pixels so as to have a mesh-like (also referred to as a lattice or matrix) shape when viewed from above.

[0120] By providing the insulating layer 132 between the EL layers 112 that exhibit different colors, the EL layers 112R, 112G, and 112B can be prevented from contacting each other. This prevents current from flowing through two adjacent EL layers 112, which would otherwise cause unintended light emission. This increases contrast, making the display device 100 a display device with high display quality. Furthermore, by providing the insulating layer 132 between each pixel electrode 111, the pixel electrodes 111 can be prevented from contacting each other. This prevents the pixel electrodes 111 from shorting out. This makes the display device 100 a highly reliable display device.

[0121] Furthermore, by providing the insulating layer 132 between adjacent light-emitting elements 110, it is possible to flatten the step caused by the region where the EL layer 112 is provided and the region where the EL layer 112 is not provided. This improves the coverage of the common electrode 115 compared to when the insulating layer 132 is not provided between adjacent light-emitting elements 110, for example, when a gap is formed. This prevents the common electrode 115 from being disconnected and causing poor connection. It is also possible to prevent the common electrode 115 from being locally thinned due to the step, which would result in an increase in electrical resistance. As a result, the display device 100 can be a highly reliable display device.

[0122] Note that when the insulating layer 132 is not provided between adjacent light-emitting elements 110 of the same color, and the insulating layer 132 is formed only between light-emitting elements 110 of different colors, the insulating layer 132 can have a striped shape when viewed from above. By forming the insulating layer 132 in a striped shape, the space required to form the insulating layer 132 is smaller than when the insulating layer 132 has a grid shape. This makes it possible to increase the aperture ratio of the display device 100. Note that when the insulating layer 132 is formed in a striped shape, adjacent EL layers 112 of the same color may be processed into a strip shape so that they are continuous in the column direction.

[0123] An insulating layer containing an organic material can be suitably used for the insulating layer 132. For example, the insulating layer 132 can be made of an acrylic resin, a polyimide resin, an epoxy resin, a polyamide resin, a polyimideamide resin, a siloxane resin, a benzocyclobutene resin, a phenolic resin, or a precursor of these resins. Alternatively, the insulating layer 132 can be made of a photosensitive resin. The photosensitive resin can be a positive material or a negative material.

[0124] By using a photosensitive resin as the insulating layer 132, the insulating layer 132 can be manufactured only through exposure and development processes. This 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 a low-cost display device.

[0125] When an organic material is used for the insulating layer 132, the insulating layer 132 may contain oxygen, water, or the like. As described above, if oxygen, water, or the like enters the EL layer 112, the light-emitting element 110 may deteriorate. Here, in the display device 100, the insulating layer 132 is provided so as to be in contact with the protective layer 131. For example, the insulating layer 132 is provided so that the side surface and the bottom surface of the insulating layer 132 are in contact with the protective layer 131. This prevents oxygen, water, or the like contained in the insulating layer 132 from entering the EL layer 112, and the display device 100 can be a highly reliable display device.

[0126] 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 one another. 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. 2A and 2B show an example in which 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 three. Note that the number of protective layers 131 is not limited to the examples shown in FIGS. 2A and 2B and can be varied as appropriate depending on, for example, the manufacturing method of the display device 100, as will be described in detail later. Furthermore, 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 so as to have 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 so as to have a region overlapping with the top surface of the protective layer 131 provided between the EL layer 112 and the insulating layer 132. Note that although the end of the EL layer 112 and the end of the protective layer 133 are aligned in Figures 2A and 2B, the end of the EL layer 112 and the end of the protective layer 133 do not have to be aligned. For example, the end of the protective layer 133 may be located between the end of the protective layer 131 provided on the surface in contact with the EL layer 112 and the end 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 having high barrier properties against oxygen, water, etc. This can prevent impurities such as oxygen and water contained in the insulating layer 132, which may have an organic insulating material such as a resin, from penetrating into the common layer 114. This makes it possible to make the display device 100 a highly reliable display device.

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

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

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

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

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

[0135] 2C1 shows a cross section corresponding to dashed-dotted line C1-C2 shown in FIG. 1. In the cross section shown by dashed-dotted line C1-C2, a region 130 is provided where the connection electrode 111C and the common electrode 115 are electrically connected. While FIG. 2C1 shows an example in which a common layer 114 is provided between the connection electrode 111C and the common electrode 115, a configuration in which the common layer 114 is not provided in the region 130 is also possible. FIG. 2C2 shows a cross section corresponding to dashed-dotted line C1-C2 shown in FIG. 1 in the case where the common layer 114 is not provided in the region 130. By not providing the common layer 114 in the region 130, the connection electrode 111C and the common electrode 115 can be in contact with each other, thereby further reducing contact resistance.

[0136] In the region 130, the common electrode 115 is provided over the connection electrode 111C, and a protective layer 121 is provided to cover the common electrode 115. A protective layer 131 and an insulating layer 132 are provided in a region that does not overlap with the top surface of the connection electrode 111C, and a protective layer 133 is provided over the protective layer 131 and the insulating layer 132. In the example shown in FIG. 2C1 , the common layer 114 is provided over the connection electrode 111C, the protective layer 133, and the layer 101 including the transistor. Note that although FIGS. 2C1 and 2C2 show an example in which three protective layers 131 are provided on each side of the connection electrode 111C, one embodiment of the present invention is not limited thereto and can be appropriately changed depending on the manufacturing method of the display device 100, for example, as will be described in detail later.

[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 may have a concave shape.

[0138] 2D , the protective layer 131 may have a two-layer laminated structure, for example, a two-layer laminated structure of a protective layer 131a and a 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. In the protective layer 131 having a region in contact with the side surface and the bottom surface of the insulating layer 132, the protective layer 131b has a region in contact with the side surface and the bottom surface of the insulating layer 132, and the protective layer 131a has a region in contact with the side surface and the bottom surface of the protective layer 131b.

[0139] The protective layer 131a can be a layer formed by processing a film deposited by a method with high coverage, for example, and the protective layer 131b can be a layer formed by processing a film deposited by a method with low coverage, 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 be thick while covering steps. This effectively prevents impurities such as oxygen and water from entering the EL layer 112. This allows the display device 100 to be a highly reliable display device.

[0140] For example, the protective layer 131a may be made of an inorganic oxide or an inorganic nitride, and may include at least one of aluminum oxide, silicon oxide, silicon oxynitride, silicon nitride oxide, silicon nitride, aluminum oxynitride, hafnium oxide, etc. The protective layer 131b may be made of an inorganic nitride, and may include at least one of silicon nitride, aluminum nitride, or hafnium nitride, for example.

[0141] The thickness of the 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 the 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. Note that the protective layers 131a and 131b are preferably made of a film material and have a film thickness that is free of pinholes.

[0142] Figures 3A and 3B show modified examples of the configuration shown in 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 FIG. 3A has a flat top surface. The insulating layer 132 shown in FIG. 3B has a region overlapping with the top surface of the EL layer 112. In the structure shown in FIG. 3B, a sacrificial layer 145 is provided between the top surface of the EL layer 112 and the insulating layer 132. For example, the sacrificial layer 145 is provided between the top surface of the EL layer 112 and the protective layer 131. Here, the sacrificial layer 145 can have a two-layer stacked structure of a sacrificial layer 145a and a sacrificial layer 145b. In FIG. 3B, the sacrificial layer 145 includes a sacrificial layer 145R provided between the top surface of the EL layer 112R and the insulating layer 132, and a sacrificial layer 145G provided between the top surface of the EL layer 112G and the insulating layer 132. Details of the sacrificial layer 145 will be described later.

[0144] 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 in contact with the upper surface of the EL layer 112. In other words, the protective layer 133 may cover the side surface of the sacrificial layer 145.

[0145] [Pixel Layout] Next, pixel layouts different from that shown in Fig. 1 will be described. There are no particular limitations on the arrangement of sub-pixels, and various methods can be applied. Examples of the arrangement of sub-pixels include a stripe arrangement, an S-stripe arrangement, a matrix arrangement, a delta arrangement, a Bayer arrangement, and a pentile arrangement.

[0146] Examples of the top surface shape of the sub-pixel include a triangle, a quadrangle (including a rectangle and a square), a polygon such as a pentagon, a polygon with rounded corners, an ellipse, a circle, etc. 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] An S-stripe arrangement is applied to the pixel 103 shown in Fig. 4A. The pixel 103 shown in Fig. 4A is composed of three subpixels: subpixel 103a, subpixel 103b, and subpixel 103c. For example, as shown in Fig. 5A, the subpixel 103a may be a blue subpixel B, the subpixel 103b may be a red subpixel R, and the subpixel 103c may be a green subpixel G.

[0148] The pixel 103 shown in FIG. 4B includes a subpixel 103a having a substantially trapezoidal top surface shape with rounded corners, a subpixel 103b having a substantially triangular top surface shape with rounded corners, and a subpixel 103c having a substantially rectangular, hexagonal, or octagonal top surface shape with rounded corners. The subpixel 103a has a larger light-emitting area than the subpixel 103b. In this manner, the shape and size of each subpixel can be determined independently. For example, the size of a subpixel having a more reliable light-emitting element can be made smaller. For example, as shown in FIG. 5B, the subpixel 103a may be a green subpixel G, the subpixel 103b may be a red subpixel R, and the subpixel 103c may be a blue subpixel B.

[0149] The pixels 124a and 124b shown in Fig. 4C are arranged in a Pentile arrangement. Fig. 4C shows an example in which pixel 124a having subpixels 103a and 103b and pixel 124b having subpixels 103b and 103c are arranged alternately. For example, as shown in Fig. 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] The pixels 124a and 124b shown in Figures 4D and 4E are arranged in a delta arrangement. The pixel 124a has two subpixels (subpixels 103a and 103b) in the upper row (first row) and one subpixel (subpixel 103c) in the lower row (second row). The pixel 124b has one subpixel (subpixel 103c) in the upper row (first row) and two subpixels (subpixels 103a and 103b) in the lower row (second row). For example, as shown in Figure 5D, the subpixel 103a may be a red subpixel R, the subpixel 103b may be a green subpixel G, and the subpixel 103c may be a blue subpixel B.

[0151] FIG. 4D shows an example in which each subpixel has a substantially rectangular top surface shape with rounded corners, and FIG. 4E shows an example in which each subpixel has a circular top surface shape.

[0152] 4F shows an example in which subpixels of each color are arranged in a zigzag pattern. Specifically, when viewed from above, the positions of the upper edges of two subpixels arranged in the column direction (e.g., subpixels 103a and 103b, or subpixels 103b and 103c) are misaligned. For example, as shown in FIG. 5E, 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.

[0153] In photolithography, the finer the pattern to be processed, the more significant the effect of light diffraction becomes. This impairs the fidelity of the photomask pattern when it is transferred by exposure, making it difficult to process the resist mask into the desired shape. Therefore, even if the photomask pattern is rectangular, a pattern with rounded corners is likely to be formed. As a result, the top surface shape of the subpixel may become a polygon with rounded corners, an ellipse, a circle, or the like.

[0154] Furthermore, in a manufacturing method of a display device according to one embodiment 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 material for the EL layer and the curing temperature of the resist material, the resist film may not be cured sufficiently. A resist film that is not cured sufficiently may have 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, a circle, or the like. For example, when a resist mask with a square top surface shape is formed, a resist mask with a circular top surface shape may be formed, resulting in a circular top surface shape of the EL layer.

[0155] In order to form the top surface of the EL layer into a desired shape, a technique for correcting a mask pattern in advance (OPC (Optical Proximity Correction) technique) may be used so that the design pattern and the transfer pattern coincide with each other. Specifically, in the OPC technique, a correction pattern is added to the corners of figures on the mask pattern, for example.

[0156] [Manufacturing Method Example] An example of a manufacturing method of a display device according to one embodiment of the present invention will be described below with reference to the drawings. Here, the display device 100 shown in the above configuration example will be described as an example.

[0157] Thin films (insulating films, semiconductor films, conductive films, etc.) constituting the display device can be formed using a sputtering method, a CVD method, a vacuum deposition method, a PLD method, an ALD method, etc. CVD methods include a plasma enhanced chemical vapor deposition (PECVD) method and a thermal CVD method. One type of thermal CVD method is a metal organic chemical vapor deposition (MOCVD) method. Furthermore, ALD methods include a PEALD method and a thermal ALD method.

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

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

[0160] There are two typical photolithography methods: one is to form a resist mask on the thin film to be processed, process the thin film by etching, and then remove the resist mask; the other is to form a photosensitive thin film, and then process the thin film into the desired shape by exposure and development.

[0161] In photolithography, the light used for exposure may be, for example, i-line (wavelength 365 nm), g-line (wavelength 436 nm), h-line (wavelength 405 nm), or a mixture of these. Other light sources that can be used include ultraviolet light, KrF laser light, ArF laser light, etc. Exposure may also be performed by immersion exposure technology. Extreme ultraviolet (EUV) light or X-rays may also be used as the light used for exposure. An electron beam may also be used instead of the light used for exposure. Extreme ultraviolet light, X-rays, or an electron beam are preferred because they enable extremely fine processing. When exposure is performed by scanning a beam such as an electron beam, a photomask is not required.

[0162] The thin film can be etched by dry etching, wet etching, sandblasting, or the like.

[0163] To manufacture the display device 100, first, a layer 101 including a transistor is formed over a substrate (not shown). As described above, the layer 101 including a transistor can have, for example, a stacked structure in which an insulating layer is provided so as to cover the transistor.

[0164] The substrate may be a substrate having heat resistance sufficient to withstand at least a subsequent heat treatment. When an insulating substrate is used, a glass substrate, a quartz substrate, a sapphire substrate, a ceramic substrate, an organic resin substrate, or the like may be used. Alternatively, a semiconductor substrate such as a single-crystal semiconductor substrate made of silicon or silicon carbide, a polycrystalline semiconductor substrate, a compound semiconductor substrate such as silicon germanium, or an SOI substrate may be used.

[0165] Next, a conductive film to be the pixel electrode 111 is formed on the layer 101 including the transistors. Specifically, for example, the conductive film to be the pixel electrode 111 is formed on an insulating surface of the layer 101 including the transistors. Next, part of the conductive film is removed by etching, and the pixel electrodes 111R, 111G, 111B, and the connection electrode 111C are formed on the layer 101 including the transistors ( FIG. 6A ).

[0166] When a conductive layer that is reflective to visible light is used as the pixel electrode, it is preferable to use a material (such as silver or aluminum) that has as high a reflectance as possible over the entire wavelength range of visible light, which not only increases the light extraction efficiency of the light-emitting element but also improves color reproducibility.

[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 including a transistor. Here, the EL film 112Rf can be provided so as not to overlap with the connection electrode 111C. For example, by forming the EL film 112Rf while shielding the region including the connection electrode 111C with a metal mask, the EL film 112Rf can be formed so as not to overlap with the connection electrode 111C. The metal mask used in this case does not need to shield the pixel region of the display unit, so there is no need to use a high-resolution mask.

[0168] The EL film 112Rf includes a film containing at least a light-emitting compound. Alternatively, the EL film 112Rf may have a structure in which one or more films functioning as 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 are stacked. The EL film 112Rf can be formed by, for example, a vapor deposition method, a sputtering method, an inkjet method, or the like. However, the EL film 112Rf is not limited to these methods, and the above-described film formation methods can be used as appropriate.

[0169] Next, a sacrificial film 144Ra is formed on the EL film 112Rf, the connection electrode 111C, and the layer 101 including the transistor, and a sacrificial film 144Rb is formed on the sacrificial film 144Ra. That is, a sacrificial film having a two-layer stacked structure is formed on the EL film 112Rf, the connection electrode 111C, and the layer 101 including the transistor. Note that the sacrificial film may be a single layer, or may have a stacked structure of three or more layers. When a sacrificial film is formed in a subsequent process, a sacrificial film having a two-layer stacked structure is also formed, but it may be a single layer, or may have a stacked structure of three or more layers.

[0170] The sacrificial films 144Ra and 144Rb can be formed by, for example, sputtering, CVD, ALD, or vacuum deposition. Note that a formation method that causes less damage to the EL layer is preferable, and the sacrificial film 144Ra that is formed directly on the EL film 112Rf is preferably formed by ALD or vacuum deposition.

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

[0172] Alternatively, an oxide film can be used as the sacrificial film 144Ra. Typically, an oxide film or an oxynitride film such as silicon oxide, silicon oxynitride, aluminum oxide, aluminum oxynitride, hafnium oxide, or hafnium oxynitride can be used. Alternatively, a nitride film, for example, 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 a film formation method such as sputtering, CVD, or ALD. However, it is particularly preferable to form the sacrificial film 144Ra formed directly on the EL film 112Rf using ALD.

[0173] The sacrificial film 144Ra may be made of a metal material such as nickel, tungsten, chromium, molybdenum, cobalt, palladium, titanium, aluminum, yttrium, zirconium, or tantalum, or an alloy material containing such a metal material. In particular, it is preferable to use a low-melting-point material such as aluminum or silver.

[0174] The sacrificial film 144Ra may be made of a metal oxide such as indium gallium zinc oxide (In—Ga—Zn oxide, also referred to as IGZO). Other examples include indium oxide, indium zinc oxide (In—Zn oxide), indium tin oxide (In—Sn oxide), indium titanium oxide (In—Ti oxide), indium tin zinc oxide (In—Sn—Zn oxide), indium titanium zinc oxide (In—Ti—Zn oxide), and indium gallium tin zinc oxide (In—Ga—Sn—Zn oxide). Alternatively, for example, indium tin oxide containing silicon may be used.

[0175] The present invention can also be applied to a case where, instead of the gallium, an element M (wherein M is one or more elements selected from aluminum, silicon, boron, yttrium, copper, vanadium, beryllium, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, and magnesium) is used. In particular, it is preferable that M is one or more elements selected from gallium, aluminum, and yttrium.

[0176] The sacrificial film 144Rb can be made of any of the materials that can be used for the sacrificial film 144Ra listed above. For example, one of the materials that can be used for the sacrificial film 144Ra listed above can be selected for the sacrificial film 144Ra, and another can be selected for the sacrificial film 144Rb. Furthermore, one or more materials can be selected for the sacrificial film 144Ra from the materials that can be used for the sacrificial film 144Ra listed above, and one or more materials selected from the materials 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 ALD as the sacrificial film 144Ra and silicon nitride formed by sputtering as the sacrificial film 144Rb. In this configuration, the film formation temperature during film formation by ALD and sputtering is preferably set to a temperature between room temperature and 120°C, and preferably between room temperature and 100°C, because this reduces the impact on the EL film 112Rf. Furthermore, in the case of a stacked structure of the sacrificial films 144Ra and 144Rb, it is preferable that the stress of the stacked structure be small. Specifically, it is preferable that the stress of the stacked structure be between -500 MPa and +500 MPa, and more preferably between -200 MPa and +200 MPa, because this reduces process problems such as film peeling and delamination.

[0178] The sacrificial film 144Ra may be a film that is highly resistant to the etching process of each EL film such as the EL film 112Rf, i.e., a film with a large etching selectivity. It is particularly preferable to use a film that can be removed by wet etching, which causes little damage to each EL film, for the sacrificial film 144Ra.

[0179] The sacrificial film 144Ra may also be made of a material that can be dissolved in a chemically stable solvent. In particular, materials that dissolve in water or alcohol are suitable for use as the sacrificial film 144Ra. When forming the sacrificial film 144Ra, it is preferable to apply the sacrificial film 144Ra dissolved in a solvent such as water or alcohol using a wet film formation method, and then perform a heat treatment to evaporate the solvent. 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 formation methods that can be used to form the sacrificial film 144Ra include spin coating, dipping, spray coating, inkjet, dispensing, screen printing, offset printing, doctor knife method, slit coating, roll coating, curtain coating, and knife coating.

[0181] The sacrificial film 144Ra may be made of an organic material such as polyvinyl alcohol (PVA), polyvinyl butyral, polyvinyl pyrrolidone, polyethylene glycol, polyglycerin, pullulan, water-soluble cellulose, or alcohol-soluble polyamide resin.

[0182] The sacrificial film 144Rb may be a film having a large etching selectivity with respect to the sacrificial film 144Ra.

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

[0184] Alternatively, the sacrificial film 144Rb may be an organic film that can be used for the EL film 112Rf. For example, the same organic film as that 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 EL film 112Rf and the sacrificial film 144Rb to be formed using the same film-forming equipment. Furthermore, the sacrificial film 144Rb can be removed simultaneously when etching the EL film 112Rf, thereby simplifying the process.

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

[0186] Next, the portions of the sacrificial films 144Rb and 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 (FIG. 6C). As shown in FIG. 6C, the sacrificial layers 145Rb and 145Ra can be formed, for example, on the pixel electrode 111R and the connection electrode 111C.

[0187] Here, it is preferable to etch away a portion of the sacrificial film 144Rb using the resist mask 143a, form the sacrificial layer 145Rb, remove the resist mask 143a, and then 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 provide a high selectivity with respect to the sacrificial film 144Ra for etching the sacrificial film 144Rb. While wet etching or dry etching can be used for etching to form the hard mask, using dry etching can suppress pattern shrinkage.

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

[0189] When the sacrificial film 144Ra is etched using the sacrificial layer 145Rb as a hard mask, the resist mask 143a can be removed in a state in which the EL film 112Rf is covered with the sacrificial film 144Ra. For example, if the EL film 112Rf comes into contact with oxygen, this may adversely affect the electrical characteristics of the light-emitting element 110R. Therefore, when the resist mask 143a is removed by a method using 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] Subsequently, a part of the EL film 112Rf that is not covered with the sacrificial layer 145Ra is removed by etching to form an island-shaped or strip-shaped EL layer 112R (FIG. 6D).

[0191] Dry etching using oxygen gas for etching the EL film 112Rf can increase the etching rate. Therefore, etching can be performed under low power conditions while maintaining a sufficiently high etching rate, thereby reducing damage caused by etching. Furthermore, problems such as adhesion of reaction products generated during etching to the EL layer 112R can be suppressed.

[0192] On the other hand, if the EL film 112Rf is etched by a dry etching method using an etching gas that does not contain oxygen as a main component, the deterioration of the EL film 112Rf can be suppressed, and the display device 100 can be made into a highly reliable display device. ４ , C ４ F ８ , SF ６ , CHF ３ , Cl ２ , H ２ O, BCl ３ , and Group 18 elements. As the Group 18 element, for example, helium can be used. Also, a mixed gas of the above gas and a dilution gas that does not contain oxygen can be used as the etching gas. Note that the etching of the EL film 112Rf is not limited to the above, and may be performed by a dry etching method using other gases or a wet etching method.

[0193] If impurities adhere to the side surfaces of the EL layer 112R when the EL film 112Rf is etched to form the EL layer 112R, the impurities may penetrate into the EL layer 112R in subsequent processes. This may result in a decrease in the reliability of the display device 100. Therefore, it is preferable to remove the impurities adhered to the surface of the EL layer 112R after the EL layer 112R is formed, as this can increase 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. Here, the surface of the EL layer 112R is exposed immediately after the formation of the EL layer 112R. Specifically, the side surfaces of the EL layer 112R are exposed. Therefore, after the formation of the EL layer 112R, for example, by placing the substrate on which the EL layer 112R is formed under an inert gas atmosphere, impurities adhering to the EL layer 112R can be removed. As the inert gas, for example, any one or more selected from Group 18 elements (typically, helium, neon, argon, xenon, 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 layer 101 including the transistor, the upper and side surfaces of the pixel electrodes 111R, 111G, and 111B, the side surfaces of the EL layer 112R, the side surfaces of the sacrificial layer 145Ra, and the side surfaces and upper surface of the sacrificial layer 145Rb (Figure 7A1).

[0196] Fig. 7A2 is an enlarged view of the area surrounded by the dashed line in Fig. 7A1 As shown in Fig. 7A2 , the protective film 131Rf can have a two-layer laminated structure including a protective film 131Raf that will later become the protective layer 131Ra and a protective film 131Rbf that will later become the protective layer 131Rb.

[0197] It is preferable that the protective film 131Raf is formed by a method with high coverage, and the protective film 131Rbf is formed by a method with low coverage. 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 thick while covering steps. This effectively prevents impurities such as oxygen and water from penetrating the EL layer 112R. This allows the display device 100 to be a highly reliable display device.

[0198] The protective film 131Rf may be made of an inorganic insulating material. For example, the protective film 131Raf may be made of an inorganic oxide or an inorganic nitride, and may include at least one of aluminum oxide, silicon oxide, silicon oxynitride, silicon nitride oxide, silicon nitride, aluminum oxynitride, and hafnium oxide. The protective film 131Rbf may be made of an inorganic nitride, and may include at least one of silicon nitride, aluminum nitride, and hafnium nitride.

[0199] The protective film 131Raf is preferably formed to 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 formed to 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. The protective films 131Raf and 131Rbf are preferably formed to a film type and thickness that are free of pinholes.

[0200] Here, if the EL layer 112R comes into contact with air, impurities such as oxygen and water contained in the air may penetrate into the EL layer 112R. After the EL layer 112R is formed, 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 allows the protective film 131Rf covering the EL layer 112R to be formed without exposing the EL layer 112R to air after etching the EL film 112Rf. This prevents impurities contained in the air from penetrating into the EL layer 112R, resulting in a highly reliable display device 100. It is also preferable to perform other processes in the same apparatus, as this prevents components of the display device 112R from coming into contact with air during the manufacturing process of the display device 100 and increases the throughput of the manufacturing process of the display device 100.

[0201] Next, the protective film 131Rf is etched to form the protective layer 131R ( FIG. 7B1 ). The protective layer 131R is formed to have an area overlapping with the side surface of the EL layer 112R. The protective layer 131R is also formed to have an area overlapping with the side surfaces of the pixel electrode 111R, the pixel electrode 111G, the pixel electrode 111B, the sacrificial layer 145Ra, and the sacrificial layer 145Rb. Note that if the protective film 131Rf is thin, the protective layer 131R may not be formed in the area overlapping with the side surfaces of the pixel electrode 111R, the pixel electrode 111G, the pixel electrode 111B, the sacrificial layer 145Ra, or the sacrificial layer 145Rb.

[0202] By forming the protective layer 131R so as to have an area overlapping with the side surface of the EL layer 112R, it is possible to prevent impurities such as oxygen and water from entering the inside of the EL layer 112R from the side surface in the subsequent steps, thereby making the display device 100 a highly reliable display device.

[0203] Etching the protective film 131Rf by anisotropic etching is preferable because the protective layer 131 can be suitably formed without patterning using, for example, photolithography. For example, forming the protective layer 131 without patterning using photolithography can simplify 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 an inexpensive display device. As described above, an example of anisotropic etching is dry etching. When etching the protective film 131Rf by dry etching, the protective film 131Rf can be etched using an etching gas that can be used to etch the sacrificial film 144Ra or the sacrificial film 144Rb, for example.

[0204] Fig. 7B2 is an enlarged view of the area surrounded by the dashed line in Fig. 7B1. As shown in Fig. 7B2, the protective layer 131R can have a two-layer laminated structure of a protective layer 131Ra and a protective layer 131Rb.

[0205] 6C and 6D , etching the EL film 112Rf using an oxygen-containing gas may change the surface state of the pixel electrode 111G and the pixel electrode 111B. For example, the surfaces of the pixel electrode 111G and the pixel electrode 111B may become hydrophilic. For example, if the upper surfaces of the pixel electrodes 111G and 111B are layers containing indium tin oxide, etching the EL film 112Rf using an oxygen-containing gas may cause the layers containing indium tin oxide 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 hydrophilic and hydrophobic surfaces 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 between the EL film formed in a later process and the EL film may be lower. Therefore, in a later process, the EL film may peel off at the interface with the pixel electrode 111G or the interface with the pixel electrode 111B. Furthermore, when the EL film 112Rf is etched using a gas containing oxygen, in addition to the change in the surface state described above, the work function of the surfaces of the pixel electrodes 111G and 111B may change.

[0206] Therefore, by performing a hydrophobic treatment on the surfaces of the pixel electrodes 111G and 111B, peeling of the EL film formed in a later process can be suppressed. This makes it possible to make the display device 100 a highly reliable display device. Furthermore, the yield in manufacturing 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] The hydrophobic treatment can be performed by, for example, fluorine modification of the pixel electrodes 111G and 111B. The fluorine modification can be performed by, for example, a treatment using a gas containing fluorine, a heat treatment, or a plasma treatment in a gas atmosphere containing fluorine. As the gas containing fluorine, for example, fluorine gas can be used, and for example, fluorocarbon gas can be used. As the fluorocarbon gas, for example, carbon tetrafluoride (CF４ ) Gas, C ４ F ６ Gas, C ２ F ６ Gas, C ４ F ８ Gas or C ５ F ８ As a gas containing fluorine, for example, SF ６ Gas, NF ３ gas, or CHF ３ Gases such as 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 hydrophobized by performing plasma treatment on the surfaces of the pixel electrodes 111G and 111B in a gas atmosphere containing a Group 18 element such as argon, followed by treatment using a silylating agent. Examples of the silylating agent that can be used include hexamethyldisilazane (HMDS) and trimethylsilylimidazole (TMSI). Furthermore, the surfaces of the pixel electrodes 111G and 111B can be hydrophobized by performing plasma treatment on the surfaces of the pixel electrodes 111G and 111B in a gas atmosphere containing a Group 18 element such as argon, followed by treatment using a silane coupling agent.

[0209] By performing plasma treatment on the surfaces of the pixel electrodes 111G and 111B in a gas atmosphere containing a Group 18 element such as argon, it is possible to damage the surfaces of the pixel electrodes 111G and 111B. This makes it easier for methyl groups contained in a silylating agent such as HMDS to bond to the surfaces of the pixel electrodes 111G and 111B. It also makes it easier for silane coupling to occur using a silane coupling agent. As described above, by performing plasma treatment on the surfaces of the pixel electrodes 111G and 111B in a gas atmosphere containing a Group 18 element such as argon, and then performing treatment using a silylating agent or a silane coupling agent, it is possible to hydrophobize the surfaces of the pixel electrodes 111G and 111B.

[0210] The treatment using a silylating agent or a silane coupling agent can be performed by applying the silylating agent or the silane coupling agent using, for example, a spin coating method or a dipping method. Alternatively, the treatment using a silylating agent or the silane coupling agent can be performed by, for example, using a vapor phase method to form a film containing a silylating agent or a film containing a silane coupling agent on the pixel electrode 111G, the pixel electrode 111B, etc. In the vapor phase method, first, a material containing a silylating agent or a material containing a silane coupling agent is volatilized to incorporate the silylating agent or the silane coupling agent into an atmosphere. Next, a substrate on which the pixel electrodes 111G, the pixel electrodes 111B, etc. are formed is placed in the atmosphere. This allows a film containing the silylating agent or the silane coupling agent to be formed on the pixel electrodes 111G, the pixel electrodes 111B, etc., and the surfaces of the pixel electrodes 111G and the pixel electrodes 111B to be 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 transistor-including layer 101. 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 contacting the EL layer 112R. For example, with regard to the formation of the EL film 112Gf, the description of the formation of the EL film 112Rf can be referred to.

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

[0213] Next, portions of the sacrificial films 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 ( FIG. 8B ). Here, the sacrificial layers 145Gb and 145Ga can be formed on the pixel electrode 111G. For the formation of the sacrificial layers 145Gb and 145Ga and the removal of the resist mask 143b, the description of the formation of the sacrificial layers 145Rb and 145Ra and the removal of the resist mask 143a can be referenced.

[0214] Next, the portions of the EL film 112Gf not covered by the sacrificial layer 145Ga are removed by etching to form island- or strip-shaped EL layers 112G ( FIG. 8C ). For example, the description of the formation of the EL layer 112R can be referenced for the formation of the EL layer 112G. Similarly to the EL layer 112R, it is also preferable to remove impurities adhering to the surface of the EL layer 112G. For example, after the formation of the EL layer 112G, the substrate on which the EL layer 112G is formed can be placed in an inert gas atmosphere to remove impurities adhering to the EL layer 112G.

[0215] Next, a protective film 131Gf, which will later become the protective layer 131G, is formed to cover the top surface of the transistor-containing layer 101, the top surface of the pixel electrode 111B, the side surfaces of the EL layer 112G, the side surfaces of the protective layer 131R, the top surface of the sacrificial layer 145Rb, the side surfaces of the sacrificial layer 145Ga, and the side surfaces and top surface of the sacrificial layer 145Gb ( FIG. 9A1 ). For example, the description of the formation of the protective film 131Rf can be referenced for the formation of the protective film 131Gf. Here, it is preferable to perform the steps 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] 9A2 shows an enlarged view of the area surrounded by the dashed line in FIG. 9A1. As shown in FIG. 9A2, the protective film 131Gf can have a two-layer structure including a protective film 131Gaf that will later become the protective layer 131Ga and a protective film 131Gbf that will later become the protective layer 131Gb. For the protective film 131Gaf and the protective film 131Gbf, the descriptions of the protective film 131Raf and the protective film 131Rbf can be referenced, respectively.

[0217] Next, the protective film 131Gf is etched to form the protective layer 131G ( FIG. 9B1 ). The protective layer 131G is formed to have an area overlapping the side surface of the EL layer 112G. The protective layer 131G is also formed to have an area overlapping 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 protective film 131Gf is thin, the protective layer 131G may not be formed in the area overlapping 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 referenced for the formation of the protective layer 131G.

[0218] 9B2 shows an enlarged view of the area surrounded by the dashed line in FIG. 9B1. As shown in FIG. 9B2, the protective layer 131G may have a two-layer structure of a protective layer 131Ga and a protective layer 131Gb. For the protective layer 131Ga and the protective layer 131Gb, the descriptions of the protective layer 131Ra and the protective layer 131Rb, respectively, can be referenced.

[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 transistor-containing layer 101. 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 contacting the EL layer 112G. For example, the formation of the EL film 112Bf can be referred to the description of the formation of the EL film 112Rf.

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

[0221] Next, portions of the sacrificial films 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 ( FIG. 10B ). Here, the sacrificial layers 145Bb and 145Ba can be formed on the pixel electrode 111B. For the formation of the sacrificial layers 145Bb and 145Ba and the removal of the resist mask 143c, the description of the formation of the sacrificial layers 145Rb and 145Ra and the removal of the resist mask 143a can be referenced.

[0222] Next, the portions of the EL film 112Bf not covered by the sacrificial layer 145Ba are removed by etching to form island- or strip-shaped EL layers 112B ( FIG. 10C ). For example, the description of the formation of the EL layer 112R can be referenced for the formation of the EL layer 112B. Furthermore, as with the EL layers 112R and 112G, it is preferable to remove impurities adhering to the surface of the EL layer 112B. For example, after the formation of the EL layer 112B, the substrate on which the EL layer 112B is formed can be placed under an inert gas atmosphere to remove impurities adhering to the EL layer 112B.

[0223] Next, a protective film 131Bf, which will later become the protective layer 131B, is formed to cover the top surface of the transistor-containing layer 101, the side surfaces of the EL layer 112B, the side surfaces of the protective layer 131G, the top surface of the sacrificial layer 145Rb, the top surface of the sacrificial layer 145Gb, the side surfaces of the sacrificial layer 145Ba, and the side surfaces and top surface of the sacrificial layer 145Bb ( FIG. 11A ). For example, the description of the formation of the protective film 131Rf can be referenced for the formation of the protective film 131Bf. Here, it is preferable to perform the steps 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] FIG. 11B shows an enlarged view of region 160a shown in FIG. 11A, and FIG. 11C shows an enlarged view of region 160b shown in FIG. 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 FIGS. 11B and 11C, protective film 131Bf can have a two-layer laminated structure including protective film 131Baf, which will later become protective layer 131Ba, and protective film 131Bbf, which will later become protective layer 131Bb. For the protective film 131Baf and the protective film 131Bbf, please refer to the descriptions of the protective film 131Raf and the 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 ( FIG. 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. Furthermore, 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 by a spin coating method, a spray method, a screen printing method, a painting method, or the like.

[0227] 12A, the insulating film 132f may have gentle unevenness that reflects the unevenness of the surface on which it is formed. Also, the insulating film 132f may be flattened.

[0228] Next, the insulating layer 132 is formed (FIG. 12B1). Here, 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 the steps of exposure and development, the insulating layer 132 can be formed without using, for example, a dry etching method. This simplifies the process. Furthermore, damage to the EL layer 112 caused by etching the insulating film 132f can be reduced. Note that a portion of the upper part of the insulating layer 132 may be further etched to adjust the surface height.

[0229] Alternatively, the upper surface of the insulating film 132f may be etched substantially uniformly to form the insulating layer 132. Such 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] Fig. 12B2 shows an enlarged view of the area surrounded by the dashed line in Fig. 12B1. As shown in Fig. 12B2, the insulating layer 132 may have a concave shape. Here, the height of the upper end of the insulating layer 132 may be equal to or lower than the height of the upper surface of the protective film 131Bbf, for example.

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

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

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

[0235] Next, the protective film 131Bf is etched to form the protective layer 131B ( FIG. 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 referred to the description of the formation of the protective layer 131R.

[0236] Next, the sacrificial layers 145Rb, 145Gb, and 145Bb are removed by, for example, etching (FIG. 14B1). The sacrificial layer 145b is preferably etched under conditions that provide a high etching selectivity with respect to the sacrificial layer 145a. Note that the sacrificial layer 145b does not necessarily have to be removed.

[0237] 14B2 shows an enlarged view of the region surrounded by a dashed line in FIG. 14B1. In FIG. 14B2, part of the protective layer 131 is removed by removing the sacrificial layer 145b, and the top surface of the protective layer 131, which has a region in contact with the side surface of the EL layer 112, coincides with the top surface of the sacrificial layer 145a. However, one embodiment of the present invention is not limited to this. For example, the top surface of the protective layer 131, which has a region in contact with the side surface of the EL layer 112, may be higher than the top surface of the sacrificial layer 145a.

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

[0239] The protective film 133f can be made of an inorganic insulating material, such as a nitride. Specifically, the protective film 133f can contain at least one of silicon nitride, aluminum nitride, and hafnium nitride. Alternatively, the protective film 133f can be made of an oxide or an oxynitride, such as silicon oxide, silicon oxynitride, aluminum oxide, aluminum oxynitride, hafnium oxide, or hafnium oxynitride.

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

[0241] 15B2 shows an enlarged view of the area surrounded by the dashed line in FIG. 15B1. In FIG. 15B2, the end of the protective layer 133 coincides with the end of the sacrificial layer 145a, but the end of the protective layer 133 does not have to coincide with the end of the sacrificial layer 145a. For example, the protective layer 133 may have an area overlapping with the sacrificial layer 145a. Furthermore, the end of the protective layer 133 may be located between the end of the sacrificial layer 145a and the end of the insulating layer 132.

[0242] Next, the sacrificial layers 145Ra, 145Ga, and 145Ba are removed by, for example, etching ( FIG. 16A ). The sacrificial layers 145Ra, 145Ga, and 145Ba are preferably removed by a method that minimizes damage to the EL layer 112, for example, by wet etching. Note that, when the sacrificial layers 145Ra, 145Ga, and 145Ba are removed, 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 process is performed to remove water and the like adsorbed on the surfaces of the EL layers 112R, 112G, and 112B. The vacuum bake is preferably performed within a temperature range that does not alter the organic compounds contained in the EL layers 112R, 112G, and 112B, for example, at a temperature of 70° C. or higher and 120° C. or lower, more preferably 80° C. or higher and 100° C. or lower. Note that if there is little water and the like adsorbed on the surfaces of the EL layers 112R, 112G, and 112B, for example, and if there is little effect on the reliability of the display device 100, for example, the vacuum bake process may not be performed.

[0244] Next, the common layer 114 is formed on the EL layer 112, the protective layer 133, and the layer 101 including the transistor. As described above, the common layer 114 has at least one of a hole injection layer, a hole transport layer, a hole blocking layer, an electron blocking layer, an electron transport layer, and an electron injection layer, 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, an inkjet method, or the like. Note that, in a configuration in which the common layer 114 is not provided on the connection electrode 111C, a metal mask that shields the connection electrode 111C may be used in forming the common layer 114. The metal mask used in this case does not need to shield the pixel region of the display unit, so there is no need to use a high-resolution mask.

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

[0246] Next, a protective layer 121 is formed on the common electrode 115 (FIG. 16B). When an inorganic insulating film is used as the protective layer 121, it is preferable to form the protective layer 121 by, 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 by, for example, an inkjet method, because this allows a uniform film to be formed in a desired area.

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

[0248] As described above, in the manufacturing method of a display device according to one embodiment of the present invention, EL layers are individually formed by, for example, photolithography and etching without using a shadow mask such as a metal mask. This allows the EL layer to have a fine pattern. Therefore, by the manufacturing method of a display device according to one embodiment of the present invention, a display device with high definition and a high aperture ratio can be manufactured. Furthermore, a display device with high resolution and a large display device can be manufactured. Furthermore, because the EL layers can be individually formed, a display device with extremely vivid images, high contrast, and high display quality can be manufactured.

[0249] 2A , 2B , 2D , and the like, 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, but the structure of the display device of one embodiment 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 area surrounded by the dashed-dotted line in Fig. 17A . 17A, 17B, 17C, and 17D are modified examples of the configurations shown in FIGS. 2A, 2B, 2C1, and 2D, and differ in that the side surface of pixel electrode 111R coincides with the side surface of EL layer 112R, the side surface of pixel electrode 111G coincides with the side surface of EL layer 112G, and the side surface of pixel electrode 111B coincides with the side surface of EL layer 112B.

[0250] Fig. 18A is a cross-sectional view corresponding to dashed-dotted line A1-A2 in Fig. 1, Fig. 18B is a cross-sectional view corresponding to dashed-dotted line B1-B2 in Fig. 1, Fig. 18C is a cross-sectional view corresponding to dashed-dotted line C1-C2 in Fig. 1, and Fig. 18D is an enlarged view of the area surrounded by the dashed-dotted line in Fig. 18A. Figs. 18A, 18B, 18C, and 18D are modifications of the configurations shown in Figs. 2A, 2B, 2C1, and 2D, and differ in that the side surfaces of EL layer 112R are positioned outward from the side surfaces of pixel electrode 111R, the side surfaces of EL layer 112G are positioned outward from the side surfaces of pixel electrode 111G, and the side surfaces of EL layer 112B are positioned outward from the side surfaces of pixel electrode 111B. In the configurations shown in Figs. 18A and 18B, etc., EL layer 112 is provided so as to cover the side surfaces of pixel electrode 111.

[0251] Fig. 19A is a cross-sectional view corresponding to dashed dotted line A1-A2 in Fig. 1, Fig. 19B is a cross-sectional view corresponding to dashed dotted line B1-B2 in Fig. 1, Fig. 19C is a cross-sectional view corresponding to dashed dotted line C1-C2 in Fig. 1, and Fig. 19D is an enlarged view of the area surrounded by the dashed dotted line in Fig. 19A. Figs. 19A, 19B, 19C, and 19D are modified examples of the configurations shown in Figs. 2A, 2B, 2C1, and 2D, and differ in that the protective layer 133 is not provided. The configurations shown in Figs. 19A to 19D can have, for example, an area where the insulating layer 132 and the common layer 114 are in contact with each other.

[0252] By omitting the protective layer 133, the step of forming the protective layer 133 is not required, which simplifies the manufacturing process of the display device 100. Therefore, the manufacturing cost of the display device 100 can be reduced, and the display device 100 can be made into a low-cost display device.

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

[0254] 20A to 20D , the sacrificial layer 145Ra remains between the upper surface of the EL layer 112R and the protective layer 133, the sacrificial layer 145Ga remains between the upper surface of the EL layer 112G and the protective layer 133, and the sacrificial layer 145Ba remains between the upper surface of the EL layer 112B and the protective layer 133. Note that, depending on the manufacturing process of the display device 100, there are cases where the sacrificial layer 145Rb remains between the sacrificial layer 145Ra and the protective layer 133, the sacrificial layer 145Gb remains between the sacrificial layer 145Ga and the protective layer 133, and the sacrificial layer 145Bb remains between the sacrificial layer 145Ba and the protective layer 133. There are also cases where the sacrificial layers 145Ra, 145Ga, and 145Ba do not remain, and the EL layers 112R, 112G, and EL layers 112B have regions in contact with the protective layer 133. 20A to 20D, 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 a region in contact with the upper surface of the EL layer 112. In other words, the protective layer 133 may cover the side surface of the sacrificial layer 145a.

[0255] At least a part of the configuration examples exemplified in this embodiment and the corresponding drawings can be combined as appropriate with other configuration examples or drawings.

[0256] Embodiment 2 In this embodiment, a structural example of a display device according to one embodiment of the present invention will be described.

[0257] The display device of the present embodiment can be a high-resolution display device or a large-sized display device. Therefore, the display device of the present embodiment can be used as a display unit of electronic devices having relatively large screens, such as television devices, desktop or notebook personal computers, computer monitors, digital signage, large game machines such as pachinko machines, as well as digital cameras, digital video cameras, digital photo frames, mobile phones, portable game machines, smartphones, wristwatch-type terminals, tablet terminals, personal digital assistants, and sound reproducing devices.

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

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

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

[0261] The circuit 464 can be, for example, a scanning line driver circuit.

[0262] The wiring 465 has a function of supplying signals and power to the display portion 462 and the circuit 464. The signals and power are input to the wiring 465 from the outside via the FPC 472 or from the IC 473.

[0263] 21 shows an example in which an IC 473 is provided on a substrate 451 by a COG method, a COF (chip on film) method, or the like. For example, an IC including a scanning line driver circuit or a signal line driver circuit can be used as the IC 473. Note that a display module including the display device 100A may not include an IC. Alternatively, an IC may be mounted on an FPC by a COF method, for example.

[0264] [Display Device 100A] FIG. 22A shows an example of a cross section of the display device 100A, in which a part of a region including the FPC 472, a part of the circuit 464, a part of the display portion 462, and a part of a region including an end portion are cut away.

[0265] 22A includes 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, between a substrate 451 and a substrate 452. Here, in the display device 100A, the stacked structure from the substrate 451 to the insulating layer 214 corresponds to the layer 101 including the transistor in Embodiment 1.

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

[0267] Here, when a pixel of a display device has three types of sub-pixels having light-emitting elements that emit different colors, the three sub-pixels include sub-pixels of three colors of R, G, and B, or sub-pixels of three colors of yellow (Y), cyan (C), and magenta (M), etc. When a pixel of a display device has four sub-pixels, the four sub-pixels include sub-pixels of four colors of R, G, B, and white (W), or sub-pixels of four colors of R, G, B, and Y, etc.

[0268] The protective layer 121 and the substrate 452 are bonded via an adhesive layer 442. A solid sealing structure, a hollow sealing structure, or the like can be applied to seal the light-emitting element. In FIG. 22A , a space 443 surrounded by the substrate 452, the adhesive layer 442, and the protective layer 121 is filled with an inert gas (nitrogen, argon, or the like), and a hollow sealing structure is applied. The adhesive layer 442 may be provided so as to overlap with the light-emitting element. Furthermore, 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 structure exemplified in Embodiment 1 can be applied to the protective layer 121.

[0269] In openings provided in the insulating layers 214, 215, and 213 so as to expose the top surface of the conductive layer 222b of the transistor 205, parts of the conductive layer 418R, the conductive layer 418G, and the conductive layer 418B are formed along the bottom and side surfaces of the openings. The conductive layer 418R, the conductive layer 418G, and the conductive layer 418B are each connected to the conductive layer 222b of the transistor 205. Other parts of the conductive layer 418R, the conductive layer 418G, and the conductive layer 418B are provided over the insulating layer 214.

[0270] The pixel electrode 111R, the pixel electrode 111G, and the pixel electrode 111B are provided over the conductive layer 418R, the conductive layer 418G, and the conductive layer 418B.

[0271] 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 openings that reach the conductive layer 222b and are provided in the insulating layer 214, the insulating layer 215, and the insulating layer 213.

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

[0273] A protective layer 131, an insulating layer 132, and a protective layer 133 are provided in a region between the light-emitting element 110R and the light-emitting element 110G and on the insulating layer 214, and in a region between the light-emitting element 110G and the light-emitting element 110B and on the insulating layer 214. The structures exemplified in Embodiment 1 can be applied to the protective layer 131, the insulating layer 132, and the protective layer 133.

[0274] The display device 100A is a top-emission display device, so that light emitted from the light-emitting element 110 is emitted toward the substrate 452. The substrate 452 is preferably made of a material that is highly transparent to visible light.

[0275] The transistor 201 and the transistor 205 are both formed over a substrate 451. These transistors can be manufactured using the same material and through the same process.

[0276] An insulating layer 211, an insulating layer 213, an insulating layer 215, and an insulating layer 214 are provided over the substrate 451 in this order. A part of the insulating layer 211 functions as a gate insulating layer of each transistor. A part of the insulating layer 213 functions as a gate insulating layer of each transistor. The insulating layer 215 is provided to cover the transistor. The insulating layer 214 is provided to cover the transistor and functions as a planarization layer. Note that the number of gate insulating layers and the number of insulating layers covering the transistors are not limited, and each may be a single layer or two or more layers.

[0277] At least one insulating layer covering the transistor is preferably made of a material that is resistant to the diffusion of impurities such as water and hydrogen. This allows the insulating layer to function as a barrier layer. With this structure, it is possible to effectively prevent impurities from diffusing into the transistor from the outside, thereby improving the reliability of the display device.

[0278] It is preferable to use an inorganic insulating film for each of the insulating layers 211, 213, and 215. Examples of the inorganic insulating film that can be used include a silicon nitride film, a silicon oxynitride film, a silicon oxide film, a silicon nitride oxide film, an aluminum oxide film, and an aluminum nitride film. Alternatively, a hafnium oxide film, an yttrium oxide film, a zirconium oxide film, a gallium oxide film, a tantalum oxide film, a magnesium oxide film, a lanthanum oxide film, a cerium oxide film, and a neodymium oxide film may also be used. Two or more of the above insulating films may be stacked.

[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 can prevent impurities from entering from the edge of the display device 100A through the organic insulating film. Alternatively, the organic insulating film may be formed so that the edge of the organic insulating film is located inside the edge of the display device 100A, so that the organic insulating film is not exposed at the edge of the display device 100A.

[0280] An organic insulating film is preferably used for the insulating layer 214, which functions as a planarizing layer. Materials that can be used for the organic insulating film include acrylic resin, polyimide resin, epoxy resin, polyamide resin, polyimideamide resin, siloxane resin, benzocyclobutene resin, phenol resin, and precursors of these resins.

[0281] 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, it is possible to prevent impurities from entering the display unit 462 from the outside through the insulating layer 214, even when an organic insulating film is used for the insulating layer 214. This can improve the reliability of the display device 100A.

[0282] The transistor 201 and the transistor 205 each include a conductive layer 221 that functions as a gate, an insulating layer 211 that functions as a gate insulating layer, a conductive layer 222a that functions as one of a source and a drain, a conductive layer 222b that functions as the other of the source and the 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 structure of the transistor included in the display device of this embodiment is not particularly limited. For example, a planar transistor, a staggered transistor, an inverted staggered transistor, or the like can be used. Furthermore, either a top-gate transistor or a bottom-gate transistor structure may be used. Alternatively, gates may be provided above and below a semiconductor layer in which a channel is formed.

[0284] The transistor 201 and the transistor 205 have a structure in which a semiconductor layer in which a channel is formed is sandwiched between two gates. The two gates may be connected and the same signal may be supplied to drive the transistor. Alternatively, the threshold voltage of the transistor may be controlled by applying a potential for controlling the threshold voltage to one of the two gates and a potential for driving to the other.

[0285] The crystallinity of a semiconductor material used for a transistor is not particularly limited, and any of an amorphous semiconductor and a crystalline semiconductor (a microcrystalline semiconductor, a polycrystalline semiconductor, a single crystal semiconductor, or a semiconductor having a crystalline region in part) may be used. The use of a crystalline semiconductor is preferable because it can suppress deterioration of transistor characteristics.

[0286] The semiconductor layer of the transistor preferably contains metal oxide (also referred to as an oxide semiconductor). That is, the display device of this embodiment preferably uses a transistor in which a channel formation region is formed using metal oxide (hereinafter also referred to as an OS transistor). Alternatively, the semiconductor layer of the transistor may contain silicon. Examples of silicon include amorphous silicon and crystalline silicon (low-temperature polysilicon, single-crystal silicon, and the like).

[0287] The semiconductor layer preferably contains, for example, indium, M (wherein M is one or more elements selected from gallium, aluminum, silicon, boron, yttrium, tin, copper, vanadium, beryllium, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, and magnesium), and zinc. In particular, M is preferably one or more elements 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 referred to as IGZO) as the semiconductor layer. Alternatively, an oxide containing indium (In), aluminum (Al), and zinc (Zn) (also referred to 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, the atomic ratio of In in the In-M-Zn oxide is preferably equal to or greater than the atomic ratio of M. Examples of atomic ratios of metal elements in such In-M-Zn oxides include a composition in which In:M:Zn = 1:1:1 or thereabouts, a composition in which In:M:Zn = 1:1:1.2 or thereabouts, a composition in which In:M:Zn = 2:1:3 or thereabouts, a composition in which In:M:Zn = 3:1:2 or thereabouts, a composition in which In:M:Zn = 4:2:3 or thereabouts, a composition in which In:M:Zn = 4:2:4.1 or thereabouts, a composition in which In:M:Zn = 5:1:3 or thereabouts, a composition in which In:M:Zn = 5:1:6 or thereabouts, a composition in which In:M:Zn = 5:1:7 or thereabouts, a composition in which In:M:Zn = 5:1:8 or thereabouts, a composition in which In:M:Zn = 6:1:6 or thereabouts, and a composition in which In:M:Zn = 5:2:5 or thereabouts. The term "nearby composition" includes a range of ±30% of the desired atomic ratio.

[0290] For example, when describing a composition having an atomic ratio of In:Ga:Zn = 4:2:3 or thereabout, this includes a case where, when the atomic ratio of In is 4, the atomic ratio of Ga is 1 or more and 3 or less, and the atomic ratio of Zn is 2 or more and 4 or less. Furthermore, when describing a composition having an atomic ratio of In:Ga:Zn = 5:1:6 or thereabout, this includes a case where, when the atomic ratio of In is 5, the atomic ratio of Ga is more than 0.1 and 2 or less, and the atomic ratio of Zn is 5 or more and 7 or less. Furthermore, when describing a composition having an atomic ratio of In:Ga:Zn = 1:1:1 or thereabout, this includes a case where, when the atomic ratio of In is 1, the atomic ratio of Ga is more than 0.1 and 2 or less, and the atomic ratio of Zn is more than 0.1 and 2 or less.

[0291] The transistors included in the circuit 464 may have the same structure as or different from the transistors included in the display portion 462. The transistors included in the circuit 464 may all have the same structure or may have two or more types of structures. Similarly, the transistors included in the display portion 462 may all have the same structure or may have two or more types of structures.

[0292] A connection portion 204 is provided in a region of the substrate 451 where the substrate 452 does not overlap. In the connection portion 204, the wiring 465 is electrically connected to the FPC 472 via a conductive layer 468, a conductive layer 461, and a connection layer 242. The conductive layer 468 can be a conductive layer obtained by processing the same conductive film as the conductive layer 418. The conductive layer 461 can be a conductive layer obtained by processing the same conductive film as the pixel electrode 111, or a conductive layer obtained by processing a stacked film including the same conductive film as the pixel electrode 111 and the same conductive film as the optical adjustment layer. The conductive layer 461 is exposed on the top surface of the connection portion 204. This allows the connection portion 204 and the FPC 472 to be electrically connected via the connection layer 242. Note that an insulating layer 414 may be provided between the conductive layer 468 and the conductive layer 461. Specifically, the insulating layer 414 can be provided in openings provided in the insulating layer 214 , the insulating layer 215 , and the insulating layer 213 .

[0293] It is preferable to provide a light-shielding layer 417 on the surface of substrate 452 facing substrate 451. Various optical members can be disposed on the outside of substrate 452. Examples of optical members include a polarizing plate, a retardation plate, a light diffusion layer (e.g., a diffusion film), an anti-reflection layer, and a light-collecting film. The outside of substrate 452 may also be provided with an antistatic film that suppresses the adhesion of dust, a water-repellent film that makes it difficult for dirt to adhere, a hard coat film that suppresses the occurrence of scratches during use, an impact absorbing layer, or the like.

[0294] By providing the protective layer 121 that covers the light emitting element 110, impurities such as water can be prevented from entering the light emitting element 110, and the reliability of the light emitting element 110 can be improved.

[0295] In a region 228 near the edge of the display device 100A, it is preferable that the insulating layer 215 and the protective layer 121 contact each other through the opening in the insulating layer 214. In particular, it is preferable that the inorganic insulating film of the insulating layer 215 and the inorganic insulating film of the protective layer 121 contact each other. This makes it possible to prevent impurities from entering the display unit 462 from the outside via the organic insulating film. This therefore makes it possible to improve the reliability of the display device 100A.

[0296] The substrate 451 and the substrate 452 can each be made of glass, quartz, ceramic, sapphire, resin, metal, alloy, semiconductor, or the like. A material that transmits light is used for the substrate on the side from which light from the light-emitting element 110 is extracted. When a flexible material is used for the substrate 451 and the substrate 452, the flexibility of the display device can be increased. Alternatively, a polarizing plate may be used for the substrate 451 or the substrate 452.

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

[0298] When a circularly polarizing plate is superimposed on a display device, it is preferable to use a substrate with high optical isotropy as a substrate included in the display device. A substrate with high optical isotropy can also be said to have small birefringence (small amount of birefringence).

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

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

[0301] Furthermore, when a film is used as a substrate, the film may absorb water, causing deformation such as wrinkles in the display panel. Therefore, it is preferable to use a film with low water absorption for the substrate. For example, it is preferable to use a film with a water absorption rate of 1% or less, more preferably 0.1% or less, and even more preferably 0.01% or less.

[0302] The adhesive layer 442 can be made of various curable adhesives, such as a photo-curable adhesive (e.g., an ultraviolet-curable adhesive), a reactive curable adhesive, a heat-curable adhesive, or an anaerobic adhesive. Examples of such adhesives include epoxy resin, acrylic resin, silicone resin, phenolic resin, polyimide resin, imide resin, PVC (polyvinyl chloride) resin, PVB (polyvinyl butyral) resin, and EVA (ethylene vinyl acetate) resin. In particular, a material with low moisture permeability, such as epoxy resin, is preferable. A two-component resin may also be used. Alternatively, an adhesive sheet, for example, may also be used.

[0303] The connection layer 242 may be an anisotropic conductive film (ACF), an anisotropic conductive paste (ACP), or the like.

[0304] Materials that can be used for the gate, source, and drain of a transistor as well as conductive layers such as various wirings and electrodes that constitute a display device include metals such as aluminum, titanium, chromium, nickel, copper, yttrium, zirconium, molybdenum, silver, tantalum, and tungsten, and alloys containing these metals as main components, etc. Films containing these materials can be used as a single layer or a stacked layer structure.

[0305] Examples of light-transmitting conductive materials include conductive oxides such as indium oxide, indium tin oxide, indium zinc oxide, zinc oxide, and zinc oxide containing gallium, or graphene. Alternatively, metal materials such as gold, silver, platinum, magnesium, nickel, tungsten, chromium, molybdenum, iron, cobalt, copper, palladium, and titanium, or alloy materials containing such metal materials, can be used. Alternatively, nitrides of such metal materials (e.g., titanium nitride) can be used. When using metal materials or alloy materials (or their nitrides), it is preferable to thin them sufficiently to ensure light-transmitting properties. A stacked film of the above materials can also be used as the conductive layer. For example, a stacked film of an alloy of silver and magnesium and indium tin oxide is preferable because it can enhance conductivity. These materials can also be used for conductive layers such as various wirings and electrodes constituting a display device, and for conductive layers (conductive layers functioning as pixel electrodes or common electrodes) of light-emitting elements.

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

[0307] 22B is a cross-sectional view illustrating a structural example of a transistor 209, and Fig. 22C is a cross-sectional view illustrating a structural example of a transistor 210. The transistors 209 and 210 can be applied to, for example, the transistors 201 and 205 illustrated in Fig. 22A.

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

[0309] The conductive layer 222a and the conductive layer 222b are connected to the low-resistance region 231n through openings provided in the insulating layer 215 and the insulating layer 225. One of the conductive layer 222a and the conductive layer 222b functions as a source, and the other functions as a drain.

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

[0311] 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 insulating layer 225 is processed using the conductive layer 223 as a mask, thereby manufacturing the structure shown in FIG. 22C . In FIG. 22C , the insulating layer 215 is provided to cover the insulating layer 225 and the conductive layer 223, and the conductive layer 222a and the conductive layer 222b are connected to the low-resistance region 231n through openings in the insulating layer 215.

[0312] Furthermore, all of the transistors included in the pixel circuit that drives the light-emitting element may be transistors having silicon in a semiconductor layer where a channel is formed (hereinafter also referred to as Si transistors). Examples of silicon include single crystal silicon, polycrystalline silicon, and amorphous silicon. In particular, a transistor having low temperature polysilicon (LTPS) in a semiconductor layer (hereinafter also referred to as LTPS transistor) can be suitably used as the Si transistor. The LTPS transistor has high field-effect mobility and good frequency characteristics.

[0313] By using silicon transistors such as LTPS transistors, circuits that need to be driven at high frequencies (such as source driver circuits) can be built on the same substrate as the display unit, which simplifies the external circuits mounted on the display device and reduces component and mounting costs.

[0314] At least one of the transistors included in the pixel circuit preferably includes a transistor having a metal oxide as a semiconductor in which a channel is formed. An OS transistor has significantly higher field-effect mobility than an amorphous silicon transistor. Furthermore, an OS transistor has a significantly smaller source-drain leakage current in an off state (hereinafter also referred to as an off-state current), and can retain charge accumulated in a capacitor connected in series with the transistor for a long period of time. Furthermore, the use of an OS transistor can reduce the power consumption of a display device.

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

[0316] By using LTPS transistors for some of the transistors included in a pixel circuit and OS transistors for the other transistors, a display device with low power consumption and high driving capability can be realized. A configuration in which an LTPS transistor and an OS transistor are combined is sometimes referred to as LTPO. A more preferred example is a configuration in which an OS transistor is used as a transistor that functions as a switch for controlling conduction / non-conduction between wirings, and an LTPS transistor is used as a transistor for controlling current.

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

[0318] On the other hand, another transistor provided in the pixel circuit functions as a switch for controlling pixel selection / non-selection and can be called a selection transistor. The gate of the selection transistor is electrically connected to a gate line, and one of the source and drain is electrically connected to a source line (signal line). It is preferable to use an OS transistor as the selection transistor. This allows the gradation of a pixel to be maintained even when the frame frequency is significantly reduced (for example, 1 fps or less), and therefore power consumption can be reduced by stopping the driver when displaying a still image.

[0319] In this manner, one embodiment of the present invention can provide a display device that has a high aperture ratio, high definition, high display quality, and low power consumption.

[0320] A display device according to one embodiment of the present invention includes an OS transistor and a light-emitting element with a metal maskless (MML) structure. This structure can significantly reduce leakage current that may flow through the transistor and leakage current that may flow between adjacent light-emitting elements (also referred to as lateral leakage current or side leakage current, etc.). Furthermore, when an image is displayed on the display device, the viewer can observe one or more of image clarity, image sharpness, and a high contrast ratio. By using a structure in which the leakage current that may flow through the transistor and the lateral leakage current between light-emitting elements are extremely low, a display with extremely low light leakage that may occur during black display (also referred to as true black display) can be achieved.

[0321] 23 is a cross-sectional view showing an example of the configuration of the display device 100B. The display device 100B is mainly different from the display device 100A in that it is a bottom-emission type display device. Note that a description of the same parts as those of the display device 100A will be omitted.

[0322] In the display device 100B, light emitted from the light-emitting element 110 is emitted toward the substrate 451. A material that is highly transparent to visible light is preferably used for the substrate 451. On the other hand, the light-transmitting property of a material used for the substrate 452 does not matter.

[0323] 23 illustrates an example in which the light-shielding layer 417 is provided over the substrate 451, the insulating layer 253 is provided so as to cover the light-shielding layer 417, and the transistor 201, the transistor 205, and the like are provided over the insulating layer 253. The insulating layer 253 can be formed using a material similar to that which can be used for the insulating layer 211, the insulating layer 213, and the insulating layer 215.

[0324] At least a part of the configuration examples exemplified in this embodiment and the corresponding drawings can be combined as appropriate with other configuration examples or drawings.

[0325] Embodiment Mode 3 In this embodiment mode, a structural example of a display device different from that of the above embodiment mode will be described.

[0326] The display device of the present embodiment can be a high-definition display device, and can therefore be used as a display unit in, for example, wristwatch-type, bracelet-type, and other information terminals (wearable devices), as well as VR devices such as head-mounted displays, eyeglass-type AR devices, and wearable devices that can be worn on the head.

[0327] 24A shows a perspective view of a 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, and may be a display device 100D, a display device 100E, or a display device 100F, which will be described later.

[0328] The display module 280 has a substrate 291 and a substrate 292. The display module 280 has a display portion 281. The display portion 281 is a region that displays an image in the display module 280, and is a region where light from each pixel provided in a pixel portion 284 (described later) can be viewed.

[0329] 24B is a perspective view schematically illustrating the configuration on the substrate 291 side. A circuit portion 282, a pixel circuit portion 283 on the circuit portion 282, and a pixel portion 284 on the pixel circuit portion 283 are stacked on the substrate 291. A terminal portion 285 for connecting to the FPC 290 is provided in a portion of the substrate 291 that does not overlap with the pixel portion 284. The terminal portion 285 and the circuit portion 282 are electrically connected by a wiring portion 286 composed of a plurality of wirings.

[0330] The pixel portion 284 has a plurality of pixels 103 arranged periodically. An enlarged view of one pixel 103 is shown on the right side of FIG. 24B . The pixel 103 includes a light-emitting element 110R, a light-emitting element 110G, and a light-emitting element 110B that emit light of different colors. The plurality of light-emitting elements 110 are preferably arranged in a stripe array as shown in FIG. 24B . The stripe array allows the light-emitting elements of one embodiment of the present invention to be arranged at high density, thereby providing a high-resolution display device. Furthermore, various arrangement methods, such as a delta array or a pentile array, can be applied.

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

[0332] One pixel circuit 283a is a circuit that controls the light emission of three light-emitting elements 110 included in one pixel 103. One pixel circuit 283a may be configured to have three circuits that control the light emission of one light-emitting element 110. For example, the pixel circuit 283a may be configured to 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 display device.

[0333] The circuit portion 282 includes a circuit for driving each pixel circuit 283 a of the pixel circuit portion 283. For example, it is preferable that the circuit portion 282 includes one or both of a scanning line driver circuit and a signal line driver circuit. In addition, the circuit portion 282 may include at least one of an arithmetic circuit, a memory circuit, a power supply circuit, and the like.

[0334] The FPC 290 functions as wiring for supplying a video signal, a power supply potential, or the like from the outside to the circuit portion 282. An IC may be mounted on the FPC 290.

[0335] The display module 280 can be configured such that one or both of the pixel circuit unit 283 and the circuit unit 282 are stacked below the pixel unit 284, thereby enabling the aperture ratio (effective display area ratio) of the display unit 281 to be extremely high. For example, the aperture ratio of the display unit 281 can be set to 40% or more and less than 100%, preferably 50% or more and 95% or less, and more preferably 60% or more and 95% or less. Furthermore, the pixels 103 can be arranged at an extremely high density, enabling the resolution of the display unit 281 to be extremely high. For example, it is preferable that the pixels 103 are arranged in the display unit 281 at a resolution of 2000 ppi or more, preferably 3000 ppi or more, more preferably 5000 ppi or more, and even more preferably 6000 ppi or more, and 20000 ppi or less, or 30000 ppi or less.

[0336] Because such a display module 280 has 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 in which the display unit of the display module 280 is viewed through lenses, the display module 280 has an extremely high-resolution display unit 281, so even if the display unit is enlarged with lenses, the 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 units. For example, it can be suitably used in the display unit of a wearable electronic device such as a wristwatch.

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

[0338] The transistor 310 has a channel formation region in a substrate 301. The substrate 301 can be, for example, a semiconductor substrate such as a single crystal silicon substrate. The transistor 310 includes a part 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 in which the substrate 301 is doped with impurities and functions as a source or drain. The insulating layer 314 is provided to cover a 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] In addition, an insulating layer 261 is provided to cover the transistor 310 , and a capacitor 240 is provided over the insulating layer 261 .

[0341] The capacitor 240 has a conductive layer 241, a conductive layer 245, and an insulating layer 243 located therebetween. 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 a dielectric of the capacitor 240.

[0342] The conductive layer 241 is provided over the insulating layer 261 and is buried in the insulating layer 254. The conductive layer 241 is electrically connected to one of the source and the drain of the transistor 310 by a plug 271 buried in the insulating layer 261. The insulating layer 243 is provided to cover the conductive layer 241. The conductive layer 245 is provided in a region overlapping with the conductive layer 241 with the insulating layer 243 interposed therebetween.

[0343] An insulating layer 255 is provided to cover the capacitor 240, and the 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 with a resin layer 419.

[0344] 24A and 24B, and the substrate 420 corresponds to the substrate 292 in Fig. 24A. The stacked structure from the substrate 301 to the insulating layer 255 corresponds to the layer 101 including the transistor in Embodiment 1.

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

[0346] 26 is different from the display device 100C mainly in the configuration of the transistors. Note that descriptions of parts that are the same as those of the display device 100C may be omitted.

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

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

[0349] 24A and 24B. The substrate 331 may be an insulating substrate or a semiconductor substrate.

[0350] An insulating layer 332 is provided over a 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 being released from the semiconductor layer 321 toward the insulating layer 332. The insulating layer 332 can be, for example, a film through which hydrogen or oxygen is less likely to diffuse than a silicon oxide film, such as an aluminum oxide film, a hafnium oxide film, or a silicon nitride film.

[0351] A conductive layer 327 is provided over the insulating layer 332, and an insulating layer 326 is provided to cover the conductive layer 327. The conductive layer 327 functions as a first gate electrode of the transistor 320, and part of the insulating layer 326 functions as a first gate insulating layer. An oxide insulating film such as a silicon oxide film is preferably used for at least a portion of the insulating layer 326 that is in contact with the semiconductor layer 321. The top surface of the insulating layer 326 is preferably planarized.

[0352] The semiconductor layer 321 is provided over the insulating layer 326. The semiconductor layer 321 preferably includes a metal oxide film having semiconductor properties.

[0353] The pair of conductive layers 325 are provided over and in contact with the semiconductor layer 321 and function as a source electrode and a drain electrode.

[0354] An insulating layer 328 is provided to cover top surfaces and side surfaces of the pair of conductive layers 325 and side surfaces of the semiconductor layer 321, and an insulating layer 264 is provided over the insulating layer 328. The insulating layer 328 functions as a barrier layer that prevents impurities such as water or hydrogen from diffusing from the insulating layer 264 or the like to the semiconductor layer 321 and prevents oxygen from being released from the semiconductor layer 321. The insulating layer 328 can be an insulating film similar to the insulating layer 332.

[0355] Openings reaching the semiconductor layer 321 are provided in the insulating layer 328 and the insulating layer 264. Inside the openings, an insulating layer 323 and a conductive layer 324 are buried, which are in contact with side surfaces of the insulating layer 264, the insulating layer 328, and the conductive layer 325 and an 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 planarized so that their heights are approximately the same, and insulating layers 329 and 265 are provided to cover them.

[0357] The insulating layer 264 and the insulating layer 265 function as interlayer insulating layers. The insulating layer 329 functions as a barrier layer that prevents impurities such as water or hydrogen from diffusing from the insulating layer 265 or the like to the transistor 320. The insulating layer 329 can be formed using an insulating film similar to the insulating layer 328 and the insulating layer 332.

[0358] The plug 274 electrically connected to one of the pair of conductive layers 325 is provided to be embedded in the insulating layer 265, the insulating layer 329, the insulating layer 264, and the insulating layer 328. Here, the plug 274 preferably includes a conductive layer 274a covering the side surfaces of the openings of the insulating layer 265, the insulating layer 329, the insulating layer 264, and the insulating layer 328 and part of the top surface of the conductive layer 325, and a conductive layer 274b in contact with the top surface of the conductive layer 274a. In this case, the conductive layer 274a is preferably made of a conductive material through which hydrogen and oxygen do not easily diffuse.

[0359] The display device 100D has the same configuration as the display device 100C, from the insulating layer 254 to the substrate 420. In the display device 100D, the stacked structure from the substrate 331 to the insulating layer 255 corresponds to the layer 101 including a transistor in Embodiment 1.

[0360] [Display Device 100E] A display device 100E shown in FIG. 27 has a stacked structure of a transistor 310A and a transistor 310B, each of which has a channel formed in a semiconductor substrate.

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

[0362] 24A and 24B, and the substrate 420 corresponds to the substrate 292 in Fig. 24A. The stacked structure from the substrate 301A to the insulating layer 255 corresponds to the layer 101 including 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 that is provided on the back surface of the substrate 301B (the surface on the substrate 301A side). 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 the substrate 301A and the substrate 301B.

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

[0366] [Display Device 100F] A display device 100F shown in FIG. 28 has a stacked structure of a transistor 310 in which a channel is formed in a substrate 301 and a transistor 320 in which a channel is formed and a semiconductor layer containing metal oxide.

[0367] 24A and 24B, and the substrate 420 corresponds to the substrate 292 in Fig. 24A. The stacked structure from the substrate 301 to the insulating layer 255 corresponds to the layer 101 including the transistor in Embodiment 1.

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

[0369] The transistor 320 can be used as a transistor included in a pixel circuit. The transistor 310 can be used as a transistor included in a pixel circuit or a driver circuit (scanning line driver circuit or signal line driver circuit) for driving the pixel circuit. The transistors 310 and 320 can be used as transistors included in various circuits such as an arithmetic circuit or a memory circuit.

[0370] By using this configuration, not only the pixel circuit but also, for example, a driver circuit can be formed directly under the light-emitting element, which makes it possible to reduce the size of the display device compared to when the driver circuit is provided around the periphery of the display area.

[0371] At least a part of the configuration examples exemplified in this embodiment and the corresponding drawings can be combined as appropriate with other configuration examples or drawings.

[0372] Embodiment 4 In this embodiment, a light-emitting element that can be used for a display device that is one embodiment of the present invention will be described.

[0373] 29A , the light-emitting element has an EL layer 786 between a pair of electrodes (a lower electrode 772 and an upper electrode 788). The EL layer 786 can be formed of a plurality of layers, such as a layer 4420, a light-emitting layer 4411, and a layer 4430. The layer 4420 can have, for example, a layer containing a substance with high electron-injection properties (electron-injection layer) and a layer containing a substance with high electron-transport properties (electron-transport layer). The light-emitting layer 4411 contains, for example, a light-emitting compound. The layer 4430 can have, for example, a layer containing a substance with high hole-injection properties (hole-injection layer) and a layer containing a substance with high hole-transport properties (hole-transport layer).

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

[0375] 29B shows a modified example of the EL layer 786 included in the light-emitting element shown in Fig. 29A. Specifically, the light-emitting element shown in Fig. 29B includes a layer 4430-1 on the lower electrode 772, a layer 4430-2 on the layer 4430-1, a light-emitting layer 4411 on the layer 4430-2, a layer 4420-1 on the light-emitting layer 4411, a layer 4420-2 on the layer 4420-1, and an upper electrode 788 on the layer 4420-2. For example, when the lower electrode 772 is an anode and the upper electrode 788 is a cathode, the layer 4430-1 functions as a hole-injection layer, the layer 4430-2 functions as a hole-transport layer, the layer 4420-1 functions as an electron-transport layer, and the layer 4420-2 functions as an electron-injection layer. Alternatively, when the lower electrode 772 is a cathode and the upper electrode 788 is an anode, the layer 4430-1 functions as an electron injection layer, the layer 4430-2 functions as an electron transport layer, the layer 4420-1 functions as a hole transport layer, and the layer 4420-2 functions as a hole injection layer. By using such a layer structure, it is possible to efficiently inject carriers into the light-emitting layer 4411 and increase the efficiency of carrier recombination in the light-emitting layer 4411.

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

[0377] 29E and 29F, a configuration in which a plurality of light-emitting units (EL layer 786a, EL layer 786b) are connected in series via an intermediate layer (charge generating layer) 4440 is referred to as a tandem structure in this specification. Note that, although the configuration shown in FIGS. 29E and 29F is referred to as a tandem structure in this specification, the present invention is not limited to this, and for example, the tandem structure may also be referred to as a stack structure. Note that by using a tandem structure, a light-emitting element capable of emitting light with high brightness can be obtained.

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

[0379] Furthermore, light-emitting materials that emit light of different colors may be used for the light-emitting layer 4411, the light-emitting layer 4412, and the light-emitting layer 4413. When the lights emitted by the light-emitting layer 4411, the light-emitting layer 4412, and the light-emitting layer 4413 are complementary in color, white light can be obtained. A color filter (also referred to as a coloring layer) may be provided as the layer 785 shown in Figure 29D. When white light passes through the color filter, light of a desired color can be obtained.

[0380] 29E and 29F , the light-emitting layer 4411 and the light-emitting layer 4412 may be made of 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 be made of 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. FIG. 29F shows an example in which a layer 785 is further provided. As the layer 785, one or both of a color conversion layer and a color filter (coloring layer) can be used.

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

[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, white, or the like, depending on the material forming the EL layer 786. Furthermore, the color purity can be further improved by providing the light-emitting element with a microcavity structure.

[0384] A light-emitting element that emits white light preferably has a structure in which two or more types of light-emitting materials are contained in the light-emitting layer. To obtain white light emission, light-emitting materials may be selected such that the respective emissions of the two or more light-emitting materials have a complementary color relationship. For example, by making the emission color of the first light-emitting layer and the emission color of the second light-emitting layer complementary to each other, a light-emitting element that emits white light as a whole can be obtained. The same applies to a light-emitting element having three or more light-emitting layers.

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

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

[0387] Embodiment 5 In this embodiment, a metal oxide that can be used for the OS transistor described in the above embodiment will be described.

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

[0389] The metal oxide can be formed by a sputtering method, a CVD method such as an MOCVD method, an ALD method, or the like.

[0390] <Classification of Crystal Structure> Examples of the crystal structure of an oxide semiconductor include amorphous (including completely amorphous), c-axis-aligned crystalline line (CAAC), nanocrystalline line (nc), cloud-aligned composite (CAC), single crystal, and polycrystalline.

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

[0392] For example, in the case of a quartz glass substrate, the shape of the peak in the XRD spectrum is almost symmetrical. On the other hand, in the case of an IGZO film having a crystalline structure, the shape of the peak in the XRD spectrum is asymmetrical. The asymmetrical shape of the peak in the XRD spectrum clearly indicates the presence of crystals in the film or substrate. In other words, if the shape of the peak in the XRD spectrum is not symmetrical, it cannot be said that the film or substrate is in an amorphous state.

[0393] In addition, the crystalline structure of the film or substrate can be evaluated by a diffraction pattern (also referred to as a nanobeam electron diffraction pattern) observed by nanobeam electron diffraction (NBED). For example, a halo is observed in the diffraction pattern of a quartz glass substrate, and it can be confirmed that the quartz glass is in an amorphous state. In addition, a spot-like pattern is observed in the diffraction pattern of an IGZO film formed at room temperature, rather than a halo. Therefore, it is estimated that the IGZO film formed at room temperature is neither in a crystalline state nor in an amorphous state, but in an intermediate state, and it cannot be concluded that it is in an amorphous state.

[0394] <<Structure of Oxide Semiconductor>> Note that oxide semiconductors may be classified differently from the above when focusing on their structures. For example, oxide semiconductors are classified into single-crystal oxide semiconductors and other non-single-crystal oxide semiconductors. Examples of non-single-crystal oxide semiconductors include the above-mentioned CAAC-OS and nc-OS. Non-single-crystal oxide semiconductors include polycrystalline oxide semiconductors, pseudo-amorphous-like oxide semiconductors (a-like OSs), amorphous oxide semiconductors, and the like.

[0395] Here, the above-mentioned CAAC-OS, nc-OS, and a-like OS will be described in detail.

[0396] [CAAC-OS] A CAAC-OS is an oxide semiconductor having multiple crystalline regions, each with its c-axis aligned in a specific direction. The specific direction refers to the thickness direction of the CAAC-OS film, the normal direction to the surface where the CAAC-OS film is formed, or the normal direction to the surface of the CAAC-OS film. A crystalline region is a region having periodic atomic arrangement. If the atomic arrangement is considered as a lattice arrangement, a crystalline region is also a region with a uniform lattice arrangement. Furthermore, a CAAC-OS has a region where multiple crystalline regions are connected in the a-b plane direction, and the region may have distortion. Note that distortion refers to a portion where the lattice arrangement changes between a region with a uniform lattice arrangement and a region with another uniform lattice arrangement in a region where multiple crystalline regions are connected. In other words, a CAAC-OS is an oxide semiconductor whose c-axes are aligned and whose orientation is not clearly aligned in the a-b plane direction.

[0397] Each of the multiple crystalline regions is composed of one or more minute crystals (crystals with a maximum diameter of less than 10 nm). When a crystalline region is composed of one minute crystal, the maximum diameter of the crystalline region is less than 10 nm. When a crystalline region is composed of many minute crystals, the size of the crystalline region may be several tens of nanometers.

[0398] In an In-M-Zn oxide (wherein the element M is one or more elements selected from aluminum, gallium, yttrium, tin, titanium, and the like), the CAAC-OS tends to have a layered crystal structure (also referred to as a layered structure) in which a layer containing indium (In) and oxygen (hereinafter referred to as an In layer) and a layer containing the element M, zinc (Zn), and oxygen (hereinafter referred to as an (M, Zn) layer) are stacked. Note that indium and the element M are mutually substituted. Therefore, the (M, Zn) layer may contain indium. The In layer may contain the element M. The In layer may contain Zn. The layered structure is observed as a lattice image in a high-resolution transmission electron microscope (TEM) image, for example.

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

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

[0401] When a crystalline region is observed from the specific direction, the lattice arrangement in the crystalline region is basically a hexagonal lattice, but the unit cell is not necessarily a regular hexagon and may be a non-regular hexagon. The distortion may have a pentagonal, heptagonal, or other lattice arrangement. In the CAAC-OS, no clear grain boundary can be identified even near the distortion. This indicates that the distortion in the lattice arrangement suppresses the formation of grain boundaries. This is thought to be because the CAAC-OS can tolerate distortion due to the lack of a dense arrangement of oxygen atoms in the a-b plane and the change in interatomic bond distance caused by the substitution of metal atoms.

[0402] Note that a crystal structure in which clear grain boundaries are observed is called polycrystalline. The grain boundaries act as recombination centers, and are likely to trap carriers, resulting in a decrease in the on-state current of a transistor and a decrease in field-effect mobility. Therefore, CAAC-OS, in which clear grain boundaries are not observed, is one of the crystalline oxides having a crystal structure suitable for a semiconductor layer of a transistor. Note that a structure containing Zn is preferable for forming a CAAC-OS. For example, In—Zn oxide and In—Ga—Zn oxide are suitable because they can suppress the generation of grain boundaries more effectively than In oxide.

[0403] The CAAC-OS is an oxide semiconductor with high crystallinity and no clear crystal grain boundaries. Therefore, it can be said that the CAAC-OS is less susceptible to a decrease in electron mobility due to crystal grain boundaries. Furthermore, since the crystallinity of an oxide semiconductor can be reduced by the inclusion of impurities, the formation of defects, or the like, the CAAC-OS can also be said to be an oxide semiconductor with few impurities and defects (oxygen vacancies, etc.). Therefore, an oxide semiconductor having the CAAC-OS has stable physical properties. Therefore, an oxide semiconductor having the CAAC-OS is heat-resistant and highly reliable. Furthermore, the CAAC-OS is stable even against high temperatures (so-called thermal budget) in the manufacturing process. Therefore, the use of the CAAC-OS in an OS transistor can increase the flexibility of the manufacturing process.

[0404] [nc-OS] The nc-OS has periodic atomic arrangement in a microscopic region (e.g., a region of 1 nm to 10 nm, particularly a region of 1 nm to 3 nm). In other words, the nc-OS has microcrystals. Note that the size of the microcrystals is, for example, 1 nm to 10 nm, particularly 1 nm to 3 nm, and therefore the microcrystals are also called nanocrystals. Furthermore, the nc-OS does not exhibit regularity in the crystal orientation between different nanocrystals. Therefore, no orientation is observed throughout the film. Therefore, depending on the analysis method, the nc-OS may be indistinguishable from an a-like OS or an amorphous oxide semiconductor. For example, when a structural analysis of an nc-OS film is performed using an XRD apparatus, no peak indicating crystallinity is detected in out-of-plane XRD measurement using θ / 2θ scanning. When an nc-OS film is subjected to electron diffraction (also referred to as selected-area electron diffraction) using an electron beam with a probe diameter larger than that of a nanocrystal (e.g., 50 nm or more), a diffraction pattern resembling a halo pattern is observed. On the other hand, when an nc-OS film is subjected to electron diffraction (also referred to as nanobeam electron diffraction) using an electron beam with a probe diameter close to or smaller than that of a nanocrystal (e.g., 1 nm to 30 nm), an electron diffraction pattern in which multiple spots are observed within a ring-shaped region centered on a direct spot may be obtained.

[0405] [a-Like OS] The a-like OS is an oxide semiconductor having a structure between the nc-OS and an amorphous oxide semiconductor. The a-like OS has pores or low-density regions. That is, the a-like OS has lower crystallinity than the nc-OS and CAAC-OS. Furthermore, the a-like OS has a higher hydrogen concentration in the film than the nc-OS and CAAC-OS.

[0406] <<Structure of Oxide Semiconductor>> Next, the above-described CAC-OS will be described in detail. Note that the CAC-OS relates to a material structure.

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

[0408] Furthermore, the CAC-OS has a mosaic structure in which a material is separated into a first region and a second region, and the first region is distributed throughout the film (hereinafter also referred to as a cloud structure). That is, the CAC-OS is a composite metal oxide having a structure in which the first region and the second region are mixed.

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

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

[0411] It should be noted that there are cases where a clear boundary between the first region and the second region cannot be observed.

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

[0413] The CAC-OS can be formed by sputtering without heating the substrate. When the CAC-OS is formed by sputtering, one or more of an inert gas (typically argon), oxygen gas, and nitrogen gas may be used as the deposition gas. The lower the flow rate of oxygen gas relative to the total flow rate of deposition gas during deposition, the more preferable it is. For example, the flow rate of oxygen gas relative to the total flow rate of deposition gas during deposition is preferably 0% or more and less than 30%, and more preferably 0% or more and 10% or less.

[0414] Furthermore, for example, in the case of CAC-OS in an In—Ga—Zn oxide, EDX mapping obtained using energy dispersive X-ray spectroscopy (EDX) can confirm that the CAC-OS has a structure in which a region containing In as a main component (first region) and a region containing Ga as a main component (second region) are unevenly distributed and mixed.

[0415] Here, the first region has higher conductivity than the second region. That is, the flow of carriers through the first region causes the metal oxide to exhibit conductivity. Therefore, the first region is distributed in a cloud-like manner in the metal oxide, thereby achieving a high field-effect mobility (μ).

[0416] On the other hand, the second region has higher insulating properties than the first region, that is, the second region being distributed in the metal oxide can suppress leakage current.

[0417] Therefore, when a CAC-OS is used in a transistor, the conductivity due to the first region and the insulating property due to the second region act complementarily, thereby providing the CAC-OS with a switching function (a function of turning on / off). That is, a CAC-OS has a conductive function in a part of the material and an insulating function in a part of the material, and functions as a semiconductor as a whole. By separating the conductive function and the insulating function, both functions can be maximized. Therefore, by using a CAC-OS in a transistor, a high on-current (I ｏｎ), high field-effect mobility (μ), and good switching behavior can be achieved.

[0418] Furthermore, a transistor using the CAC-OS has high reliability, and therefore, the CAC-OS is ideal for various semiconductor devices such as display devices.

[0419] Oxide semiconductors have a variety of structures, each of which has different characteristics. The oxide semiconductor of one embodiment of the present invention may include two or more of an amorphous oxide semiconductor, a polycrystalline oxide semiconductor, an a-like OS, a CAC-OS, an nc-OS, and a CAAC-OS.

[0420] <Transistor Having Oxide Semiconductor> Next, a case where the oxide semiconductor is used for a transistor will be described.

[0421] By using the oxide semiconductor for a transistor, a transistor with high field-effect mobility and high reliability can be realized.

[0422] For the transistor, an oxide semiconductor having a low carrier concentration is preferably used. For example, the carrier concentration of the oxide semiconductor is 1×10 １７ cm −３ Below 1 × 10, preferably １５ cm −３ More preferably, 1×10 １３ cm −３ Less than 1×10, more preferably 1×10 １１ cm −３ More preferably, 1×10 １０ cm −３ is less than 1×10 −９ cm −３ The above is the case. Note that in order to reduce the carrier concentration of an oxide semiconductor film, the impurity concentration in the oxide semiconductor film may be reduced to reduce the density of defect states. In this specification and the like, a semiconductor having a low impurity concentration and a low density of defect states is referred to as a highly purified intrinsic or substantially highly purified intrinsic oxide semiconductor. Note that an oxide semiconductor having a low carrier concentration may also be referred to as a highly purified intrinsic or substantially highly purified intrinsic oxide semiconductor.

[0423] Furthermore, a highly purified intrinsic or substantially highly purified intrinsic oxide semiconductor film has a low density of defect states, and therefore the density of trap states may also be low.

[0424] Furthermore, charges trapped in the trap states of an oxide semiconductor take a long time to dissipate and may behave like fixed charges. Therefore, a transistor in which a channel formation region is formed in an oxide semiconductor with a high density of trap states may have unstable electrical characteristics.

[0425] Therefore, in order to stabilize the electrical characteristics of a transistor, it is effective to reduce the impurity concentration in the oxide semiconductor. Furthermore, in order to reduce the impurity concentration in the oxide semiconductor, it is preferable to also reduce the impurity concentration in a nearby film. Examples of impurities include hydrogen, nitrogen, alkali metals, alkaline earth metals, iron, nickel, silicon, and the like.

[0426] <Impurities> Here, the influence of each impurity in an oxide semiconductor will be described.

[0427] When an oxide semiconductor contains silicon or carbon, which is one of Group 14 elements, defect levels are formed in the oxide semiconductor. Therefore, the concentration of silicon or carbon in the oxide semiconductor and the concentration of silicon or carbon near the interface with the oxide semiconductor (concentration obtained by secondary ion mass spectrometry (SIMS)) are calculated to be 2×10 １８ atoms / cm ３ Below 2 × 10, preferably １７ atoms / cm ３ The following applies.

[0428] Furthermore, when an oxide semiconductor contains an alkali metal or an alkaline earth metal, defect levels are formed and carriers are generated in some cases. Therefore, a transistor using an oxide semiconductor containing an alkali metal or an alkaline earth metal is likely to have normally-on characteristics. Therefore, when the concentration of the alkali metal or the alkaline earth metal in the oxide semiconductor obtained by SIMS is 1×10 １８ atoms / cm ３ Below 2 × 10, preferably１６ atoms / cm ３ Do the following:

[0429] Furthermore, when nitrogen is contained in an oxide semiconductor, electrons serving as carriers are generated, the carrier concentration increases, and the semiconductor is likely to become n-type. As a result, a transistor using an oxide semiconductor containing nitrogen as a semiconductor tends to have normally-on characteristics. Alternatively, when nitrogen is contained in an oxide semiconductor, trap states may be formed. As a result, the electrical characteristics of the transistor may become unstable. Therefore, the nitrogen concentration in the oxide semiconductor obtained by SIMS is set to 5×10 １９ atoms / cm ３ Less than 5×10 １８ atoms / cm ３ Less than 1×10, more preferably 1×10 １８ atoms / cm ３ or less, more preferably 5 × 10 １７ atoms / cm ３ Do the following:

[0430] Furthermore, hydrogen contained in an oxide semiconductor may react with oxygen bonded to a metal atom to form water, which may form an oxygen vacancy. Hydrogen entering the oxygen vacancy may generate electrons as carriers. Furthermore, some of the hydrogen may bond with oxygen bonded to a metal atom to generate electrons as carriers. Therefore, a transistor using an oxide semiconductor containing hydrogen is likely to have normally-on characteristics. Therefore, it is preferable to reduce the amount of hydrogen in the oxide semiconductor as much as possible. Specifically, the hydrogen concentration in the oxide semiconductor measured by SIMS is 1×10 ２０ atoms / cm ３ less than 1×10 １９ atoms / cm ３ less than 5×10 １８ atoms / cm ３ less than 1×10 １８ atoms / cm ３ Make it less than.

[0431] When an oxide semiconductor with sufficiently reduced impurities is used for a channel formation region of a transistor, stable electrical characteristics can be obtained.

[0432] This embodiment mode can be implemented by appropriately combining at least a part thereof with other embodiment modes described in this specification.

[0433] Embodiment 6 In this embodiment, an electronic device according to one embodiment of the present invention will be described.

[0434] The electronic devices of this embodiment include the display device of one embodiment of the present invention. The display device of one embodiment of the present invention can easily achieve high definition, high resolution, and a large size. Therefore, the display device of one embodiment of the present invention can be used as a display portion of various electronic devices.

[0435] Furthermore, the display device of one embodiment of the present invention can be manufactured at low cost, which leads to a reduction in the manufacturing cost of electronic devices.

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

[0437] In particular, the display device of one embodiment of the present invention can be suitably used in electronic devices having a relatively small display area because it can increase the 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 glasses-type AR devices. Further, examples of wearable devices include SR devices and MR devices.

[0438] The display device of one embodiment 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). A resolution of 4K2K, 8K4K, or higher is particularly preferable. Furthermore, the pixel density (resolution) of the display device of one embodiment of the present invention is preferably 300 ppi or higher, more preferably 500 ppi or higher, more preferably 1000 ppi or higher, more preferably 2000 ppi or higher, more preferably 3000 ppi or higher, more preferably 5000 ppi or higher, and even more preferably 7000 ppi or higher. By using a display device with such high resolution or high definition, it is possible to further enhance the sense of presence and depth in electronic devices for personal use such as portable or home use.

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

[0440] The electronic device of this embodiment may have an antenna. By receiving a signal through the antenna, images, information, and the like can be displayed on a display portion. In addition, when the electronic device has an antenna and a secondary battery, the antenna may be used for contactless power transmission.

[0441] The electronic device of this embodiment may have a sensor (including a function to measure force, displacement, position, velocity, acceleration, angular velocity, rotation speed, distance, light, liquid, magnetism, temperature, chemical substance, sound, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, gradient, vibration, odor, or infrared light).

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

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

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

[0445] The display device of one embodiment of the present invention can be applied to the display portion 6502 .

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

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

[0448] A display panel 6511, an optical member 6512, and a touch sensor panel 6513 are fixed to the protective member 6510 by adhesive layers (not shown).

[0449] A part of the display panel 6511 is folded back in a region outside the display portion 6502, and an FPC 6515 is connected to the folded back part. An IC 6516 is mounted on the FPC 6515. The FPC 6515 is connected to a terminal provided on a printed circuit board 6517.

[0450] The flexible display (flexible display device) of one embodiment of the present invention can be applied to the display panel 6511. Therefore, an extremely lightweight electronic device can be realized. In addition, since the display panel 6511 is extremely thin, a large-capacity battery 6518 can be mounted thereon while keeping the thickness of the electronic device small. Furthermore, by folding back a part of the display panel 6511 and arranging a connection portion with the FPC 6515 on the back side of the pixel portion, an electronic device with a narrow frame can be realized.

[0451] 31A shows an example of a television set. A television set 7100 has a display portion 7000 built into a housing 7101. Here, the housing 7101 is supported by a stand 7103.

[0452] The display device of one embodiment of the present invention can be applied to the display portion 7000 .

[0453] 31A can be operated using operation switches provided on the housing 7101 and a separate remote control 7111. Alternatively, the display portion 7000 may be provided with a touch sensor, and the television set 7100 may be operated by touching the display portion 7000 with a finger, for example. The remote control 7111 may have a display portion that displays information output from the remote control 7111. Using operation keys or a touch panel provided on the remote control 7111, the channel and volume can be controlled, and an image displayed on the display portion 7000 can be controlled.

[0454] The television device 7100 is configured to include a receiver, a modem, and the like. Ordinary television broadcasts can be received using the receiver. Furthermore, by connecting to a wired or wireless communication network via the modem, it is possible to perform one-way (from a sender to a receiver) or two-way (between a sender and a receiver, or between receivers, etc.) information communication.

[0455] 31B shows an example of a laptop personal computer 7200. The laptop personal computer 7200 includes a housing 7211, a keyboard 7212, a pointing device 7213, and an external connection port 7214. The housing 7211 includes a display portion 7000.

[0456] The display device of one embodiment of the present invention can be applied to the display portion 7000 .

[0457] 31C and 31D show an example of digital signage.

[0458] 31C includes a housing 7301, a display portion 7000, and a speaker 7303. The digital signage 7300 may further include an LED lamp, operation keys (including a power switch or an operation switch), a connection terminal, various sensors, a microphone, and the like.

[0459] 31D shows a digital signage 7400 attached to a cylindrical pillar 7401. The digital signage 7400 has a display unit 7000 provided along the curved surface of the pillar 7401.

[0460] 31C and 31D, the display device of one embodiment of the present invention can be applied to the display portion 7000.

[0461] The larger the display unit 7000, the more information can be provided at one time. Also, the larger the display unit 7000, the more easily it will attract people's attention, which can increase the advertising effectiveness of, for example, advertisements.

[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 the user to intuitively operate it. Furthermore, when used to provide information such as route information or traffic information, the intuitive operation can improve usability.

[0463] 31C and 31D , the digital signage 7300 or the digital signage 7400 is preferably capable of wirelessly linking with an information terminal 7311 or an information terminal 7411 such as a smartphone carried by a user. For example, advertising information displayed on the display unit 7000 can be displayed on the screen of the information terminal 7311 or the information terminal 7411. By operating the information terminal 7311 or the information terminal 7411, the display on the display unit 7000 can be switched.

[0464] Furthermore, the digital signage 7300 or the digital signage 7400 can be made to run a game using the screen of the information terminal 7311 or the information terminal 7411 as an operation means (controller), thereby allowing an unspecified number of users to simultaneously participate in and enjoy the game.

[0465] FIG. 32A is a diagram showing the 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, a shutter button 8004, and the like. A detachable lens 8006 is attached to the camera 8000. Note that the lens 8006 and the housing of the camera 8000 may be integrated together.

[0467] The camera 8000 can capture an image by pressing a shutter button 8004 or touching a display portion 8002 that functions as a touch panel.

[0468] The housing 8001 has a mount with electrodes, and can be connected to a finder 8100 as well as, for example, a strobe device.

[0469] The finder 8100 includes a housing 8101, a display portion 8102, a button 8103, and the like.

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

[0471] The button 8103 has a function as, for example, a power button.

[0472] The display device of one embodiment of the present invention can be applied to a display portion 8002 of a camera 8000 and a display portion 8102 of a finder 8100. Note that the camera 8000 may have a built-in finder.

[0473] FIG. 32B is a diagram showing the appearance of the head-mounted display 8200.

[0474] The head-mounted display 8200 includes a mounting portion 8201, a lens 8202, a main body 8203, a display portion 8204, and a cable 8205. The mounting portion 8201 has a built-in battery 8206.

[0475] A cable 8205 supplies power from a battery 8206 to the main body 8203. The main body 8203 includes, for example, a wireless receiver, and can display received video information on a display portion 8204. The main body 8203 also includes a camera, and can use information on the movement of the user's eyeballs or eyelids as an input means.

[0476] The wearing unit 8201 may be provided with a plurality of electrodes at positions that come into contact with the user, capable of detecting a current that flows in accordance with the movement of the user's eyeballs. This allows the head-mounted display 8200 to have a function of recognizing the user's line of sight. The head-mounted display 8200 may also have a function of monitoring the user's pulse rate based on the current that flows through the electrodes. The wearing unit 8201 may also be provided 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 biometric information of the user on the display unit 8204, or a function of changing an image displayed on the display unit 8204 in accordance with the movement of the user's head.

[0477] The display device of one embodiment of the present invention can be applied to the display portion 8204 .

[0478] 32C to 32E are diagrams showing the appearance of a head mounted display 8300. The head mounted display 8300 includes a housing 8301, a display portion 8302, a band-shaped fixture 8304, and a pair of lenses 8305.

[0479] A user can view the display on the display portion 8302 through the lens 8305. Note that it is preferable to curve the display portion 8302 because the user can feel a high sense of presence. In addition, by viewing different images displayed in different regions of the display portion 8302 through the lens 8305, it is possible to perform, for example, three-dimensional display using parallax. Note that the present invention is not limited to a configuration in which one display portion 8302 is provided, and two display portions 8302 may be provided, with one display portion being provided for each eye of the user.

[0480] The display device of one embodiment of the present invention can be applied to the display portion 8302. The display device of one embodiment of the present invention can also achieve extremely high definition. For example, even when the display is enlarged and viewed using the lens 8305 as shown in FIG. 32E , the pixels are difficult for the user to view. That is, the display portion 8302 can be used to allow the user to view a highly realistic image.

[0481] 32F is a diagram showing the appearance of a goggle-type head-mounted display 8400. The head-mounted display 8400 includes a pair of housings 8401, an attachment portion 8402, and a buffer member 8403. A display portion 8404 and a lens 8405 are provided in each of the pair of housings 8401. By displaying different images on the pair of display portions 8404, three-dimensional display using parallax can be performed.

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

[0483] The attachment portion 8402 is preferably adjustable according to the size of the user's face and has plasticity and elasticity so as not to slip off. Furthermore, a portion of the attachment portion 8402 preferably has a vibration mechanism that functions as a bone conduction earphone. This allows the user to enjoy video and audio simply by wearing the device, without the need for separate earphones or audio equipment such as speakers. The housing 8401 may also have a function for outputting audio data via wireless communication.

[0484] The mounting portion 8402 and the buffer member 8403 are portions that come into contact with the user's face (forehead, cheek, etc.). The close contact of the buffer member 8403 with the user's face can prevent light leakage and enhance the sense of immersion. The buffer member 8403 is preferably made of a soft material so that it can be in close contact with the user's face when the user wears the head-mounted display 8400. For example, materials such as rubber, silicone rubber, urethane, or sponge can be used. Furthermore, for example, using a sponge whose surface is covered with cloth or leather (natural leather or synthetic leather) can prevent gaps from forming between the user's face and the buffer member 8403, thereby favorably preventing light leakage. Furthermore, using such a material is preferable because it not only feels good to the touch but also prevents the user from feeling cold when worn, for example, in cold seasons. It is preferable that the buffer member 8403, the mounting portion 8402, and other components that come into contact with the user's skin are removable, allowing for easy cleaning or replacement.

[0485] The electronic device shown in Figures 33A to 33F has a housing 9000, a display unit 9001, a speaker 9003, operation keys 9005 (including a power switch or an operation switch), a connection terminal 9006, a sensor 9007 (including a function to measure force, displacement, position, speed, acceleration, angular velocity, rotation speed, distance, light, liquid, magnetism, temperature, chemical substance, sound, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, gradient, vibration, odor, or infrared rays), a microphone 9008, etc.

[0486] The electronic devices shown in Figures 33A to 33F have various functions. For example, they may have a function to display various information (still images, videos, text images, etc.) on a display unit, a touch panel function, a function to display a calendar, date, time, etc., a function to control processing using various software (programs), a wireless communication function, and a function to read and process programs or data recorded on a recording medium. Note that the functions of the electronic devices are not limited to these, and they may have various other functions. The electronic devices may have multiple display units. Furthermore, the electronic devices may be provided with, for example, a camera, which may capture still images or videos and store them on a recording medium (external or built-in to the camera), and may display the captured images on the display unit.

[0487] The display device of one embodiment of the present invention can be applied to the display portion 9001 .

[0488] The electronic devices shown in Figures 33A to 33F will be described in detail below.

[0489] FIG. 33A is a perspective view showing a mobile information terminal 9101. The mobile information terminal 9101 can be used as, for example, a smartphone. Note that the mobile information terminal 9101 may be provided with a speaker 9003, a connection terminal 9006, a sensor 9007, and the like. The mobile information terminal 9101 can display text and image information on multiple surfaces. FIG. 33A shows an example in which three icons 9050 are displayed. Information 9051, indicated by a dashed rectangle, can also be displayed on another surface of the display unit 9001. Examples of the information 9051 include notification of an incoming email, SNS, or phone call, the title of the email, for example, the SNS message, the sender's name, the date and time, the remaining battery level, or signal strength. Alternatively, an icon 9050, for example, may be displayed in the position where the information 9051 is displayed.

[0490] 33B is a perspective view showing the mobile information terminal 9102. The mobile information terminal 9102 has a function of displaying information on three or more surfaces of the display unit 9001. Here, an example is shown in which information 9052, information 9053, and information 9054 are displayed on different surfaces. For example, a user can check information 9053 displayed in a position that can be observed from above the mobile information terminal 9102 while the mobile information terminal 9102 is placed in a breast pocket of clothes. The user can check the display without taking the mobile information terminal 9102 out of the pocket and decide, for example, whether to answer a call.

[0491] FIG. 33C is a perspective view showing a wristwatch-type mobile information terminal 9200. The mobile information terminal 9200 can be used as, for example, a smart watch (registered trademark). The display surface of the display unit 9001 is curved, and a display can be displayed along the curved display surface. The mobile information terminal 9200 can also communicate hands-free by intercommunicating with, for example, a headset capable of wireless communication. The mobile information terminal 9200 can also perform data transmission and charging with another information terminal through a connection terminal 9006. Charging may be performed by wireless power supply.

[0492] 33D to 33F are perspective views showing a foldable mobile information terminal 9201. Also, FIG. 33D is a perspective view of the mobile information terminal 9201 in an unfolded state, FIG. 33F is a perspective view of the mobile information terminal 9201 in a folded state, and FIG. 33E is a perspective view of a state in the process of changing from one of FIG. 33D and FIG. 33F to the other. The mobile information terminal 9201 is highly portable when folded, and has a seamless, wide display area when unfolded, providing excellent visibility of the display. The display portion 9001 of the mobile information terminal 9201 is supported by three housings 9000 connected by hinges 9055. For example, the display portion 9001 can be bent with a curvature radius of 0.1 mm or more and 150 mm or less.

[0493] At least a part of the configuration examples exemplified in this embodiment and the corresponding drawings can be combined as appropriate with other configuration examples or drawings.

[0494] In this example, a sample having a light-emitting element was manufactured and evaluated, and the results are described.

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

[0496] The light-emitting element 110R has 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 has a protective layer 131Ra on the insulating layer 101b, and a protective layer 131Rb on the protective layer 131Ra, which has an area in contact with the side surface of the EL layer 112R. Sample 200A also has 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 111Ra and the pixel electrode 111Rb constitute the pixel electrode 111R shown in embodiment 1, etc., and the protective layer 131Ra and the protective layer 131Rb constitute the protective layer 131R shown in embodiment 1, etc.

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

[0498] 34C includes 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] 34D is a diagram showing the configuration of EL layer 112R. EL layer 112 has a hole injection layer 151, a hole transport layer 152 on hole injection layer 151, a light emitting layer 153 on hole transport layer 152, a hole blocking layer 154 on light emitting layer 153, and an electron transport layer 155 on hole blocking layer 154. Here, light emitting layer 153 has a function of emitting red light.

[0500] 35A to 35E and 36A to 36D are cross-sectional views showing the steps of the method for producing sample 200A in this example.

[0501] In fabricating sample 200A, a resin layer was first formed as insulating layer 101a on a substrate (not shown) by spin coating, and then a silicon nitride layer was formed as insulating layer 101b on insulating layer 101a by CVD.

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

[0503] Next, a silicon-containing indium tin oxide film was deposited on the pixel electrode 111Ra and the insulating layer 101b by sputtering to a thickness of 100 nm as a conductive film that would later become the pixel electrode 111Rb. Part of the conductive film was then removed by wet etching to form the pixel electrode 111Rb (FIG. 35A).

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

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

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

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

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

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

[0510] Subsequently, the protective film 131Rbf was processed by dry etching to form a protective layer 131Rb (FIG. 36B). Next, the protective film 131Raf was processed by dry etching to form a protective layer 131Ra. Thereafter, the sacrificial layers 145Rb and 145Ra were removed by wet etching (FIG. 36C).

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

[0512] Subsequently, an alloy film with a silver to magnesium ratio of 10:1 was formed as the common electrode 115 on the common layer 114 by vapor deposition to a thickness of 15 nm. In this way, the light emitting element 110R was formed.

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

[0514] 37A to 37E are cross-sectional views showing the steps of the method for producing sample 200B in this example.

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

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

[0517] Thereafter, the common layer 114, the common electrode 115, and the protective layer 121 were formed in the same manner as in the sample 200A (FIG. 37E). In the manner described above, the sample 200B was formed.

[0518] In the fabrication of sample 200C, a resin layer was first formed as insulating layer 101a on a substrate (not shown) by spin coating, and then a silicon nitride layer was formed as insulating layer 101b on insulating layer 101a by CVD.

[0519] Next, a silver-palladium-copper alloy film was formed on the insulating layer 101b as the pixel electrode 111Ra by sputtering to a thickness of 100 nm, and then a silicon-containing indium tin oxide film was formed on the pixel electrode 111Ra by sputtering to a thickness of 100 nm.

[0520] Subsequently, the EL layer 112R was formed on the pixel electrode 111Rb by vapor deposition. The EL layer 112R had the structure shown in Fig. 34D, and the thicknesses of the hole injection layer 151, the hole transport layer 152, the light-emitting layer 153, the hole blocking layer 154, and the electron transport layer 155 were the same as those of the sample 200A and the sample 200B.

[0521] Thereafter, the common layer 114, the common electrode 115, and the protective layer 121 were formed in the same manner as in Sample 200A and Sample 200B. Sample 200C was formed by the method described above. As described above, when forming Sample 200C, the formation of a sacrificial layer and the patterning of the EL film by etching were not performed. It can be said that the fabrication of Sample 200C was performed entirely in a vacuum.

[0522] Fig. 38 is a graph showing the luminance-voltage characteristics of Sample 200A, Sample 200B, and Sample 200C. Fig. 39 is a graph showing the current efficiency-luminance characteristics of Sample 200A, Sample 200B, and Sample 200C. Furthermore, when the luminance of each of Sample 200A, Sample 200B, and Sample 200C was 1000 cd / m ２ Table 1 shows the characteristics of the light emitting element 110R when the temperature is around 100°C.

[0523]

[0524] 38, sample 200B required a higher voltage to obtain the same luminance than sample 200A and sample 200C. On the other hand, there was almost no difference between the luminance-voltage characteristics of sample 200A and sample 200C. In other words, it can be said that sample 200A had the same luminance-voltage characteristics as sample 200C, which was fabricated entirely in a vacuum, despite the fact that the EL film 112Rf was processed by dry etching.

[0525] 39, Samples 200A and 200B, in which the EL film 112Rf was processed by dry etching, had lower current efficiency on the low luminance side compared to Sample 200C, which was fabricated entirely in a vacuum. 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, before the EL film 112f shown in Figures 35D and 35E is formed and removed by dry etching, a protective film 131Raf is provided to cover the side surface of the EL layer 112R, as shown in Figure 35C. It has been suggested that providing the protective film 131Raf can suppress deterioration in the characteristics of the light-emitting element 110R due to the formation of the EL film 112f and its removal by dry etching.

[0527] 40 is a graph showing the change over time in normalized luminance of sample 200A, sample 200B, and sample 200C. In FIG. 40, normalized luminance indicates relative luminance based on the luminance of light-emitting element 110R at time 0, i.e., at the start of luminance measurement. The normalized luminance shown in FIG. 40 is obtained by comparing the intrinsic luminance of light-emitting element 110R with that of 7900 cd / m ２ The measurement was performed at a constant current of 100 kJ / s at room temperature. A graph showing the change in normalized luminance over time is called a reliability curve.

[0528] 40, there was no significant difference in the slope of the reliability curve for sample 200A, sample 200B, or sample 200C. This confirmed that there was no significant difference in the reliability of sample 200A, sample 200B, or sample 200C.

[0529] As described above, by providing the protective layers 131Ra and 131Rb, even when the EL film is processed by dry etching, it is possible to fabricate a light-emitting element that has the same driving voltage and reliability as a light-emitting element fabricated entirely in a vacuum, and in which the decrease in current efficiency is suppressed more than when the protective layers 131Ra and 131Rb are not provided.

[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: connection 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, 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: connection portion, 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: capacitor, 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 conductive layer, 280: display module, 281: display section, 282: circuit section, 283: pixel circuit section, 283a: pixel circuit, 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: insulating 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 section, 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 device, 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 device, 7101: Housing, 7103: Stand, 7111: Remote control device, 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 device, 7400: Digital signage, 7401: Pillar, 7411: Information terminal device, 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: Equipment Mounting part, 8202: lens, 8203: main body, 8204: display part, 8205: cable, 8206: battery, 8300: head mounted display, 8301: housing, 8302: display part, 8304: fixing device, 8305: lens, 8400: head mounted display, 8401: housing, 8402: mounting part, 8403: cushioning member, 8404: display part, 8405: lens, 9000: Housing, 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: Portable information terminal, 9102: Portable information terminal, 9200: Portable information terminal, 9201: Portable information terminal,

Claims

1. A light-emitting 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 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 the 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 an area overlapping a side surface of the first pixel electrode, a side surface of the second pixel electrode, a side surface of the first EL layer, and a side surface 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; The display device, wherein the common electrode is provided on the first EL layer, on the second EL layer, and on the second protective layer.

2. In claim 1, The display device, wherein the insulating layer is provided between the first EL layer and the second EL layer.

3. In claim 1 or 2, The display device has a third protective layer, The third protective layer has an area in contact with a side surface and a bottom surface of the first protective layer.

4. In claim 3, The first to third protective layers include an inorganic material.

5. In any one of claims 1 to 4, the first protective layer has an area in contact with a side surface and a bottom surface of the insulating layer, the second protective layer has a region in contact with an upper surface of the insulating layer, The first protective layer and the second protective layer include a nitride.

6. In any one of claims 1 to 5, The first protective layer and the second protective layer each include at least one of silicon nitride, aluminum nitride, or hafnium nitride.

7. In any one of claims 1 to 6, The insulating layer comprises an organic material.

8. In any one of claims 1 to 7, a common layer is provided between the first EL layer, the second EL layer, and the second protective layer and the common electrode; The common layer has at least one of a hole injection layer, a hole transport layer, a hole blocking layer, an electron blocking layer, an electron transport layer, and an electron injection layer.

9. In any one of claims 1 to 8, A display device having an area in which the distance between a side surface of the first EL layer and a side surface of the second EL layer is 1 μm or less.

10. In claim 9, A display device having an area in which the distance between a side surface of the first EL layer and a side surface of the second EL layer is 100 nm or less.

11. A display device according to any one of claims 1 to 10; A display module having at least one of a connector and an integrated circuit.

12. A display module according to claim 11; An electronic device having at least one of a battery, a camera, a speaker, and a microphone.