Indication device

Abstract

Provided is a display device having both high display quality and high definition. This display device comprises a light-emitting element and a connection part. The connection part is provided along the outer periphery of a display region in which the light-emitting element is provided. The light-emitting element has a pixel electrode, a first EL layer on the pixel electrode, a second EL layer on the first EL layer, and a common electrode on the second EL layer. The connection part has a connection electrode, the second EL layer on the connection electrode, and the common electrode on the second EL layer. The second EL layer has a first region that abuts on the connection electrode, and a second region that abuts on the common electrode. The area of a region where the first region and the second region overlap each other when viewed from above is 40000 square micrometers or more. The second EL layer has a region with a film thickness of 0.5-15 nm. The second EL layer contains a substance having a high electron injection property.

Description

[Technical Field]

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

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

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

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

[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 liquid crystal display devices and the like, 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. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-324673 Summary of the Invention [Problem to be solved by the invention]

[0007] An object of one embodiment of the present invention is to provide a display device that can easily achieve high resolution and a manufacturing method thereof.An object of one embodiment of the present invention is to provide a display device that combines high display quality and high resolution.An object of one embodiment of the present invention is to provide a display device with high contrast.An object of one embodiment of the present invention is to provide a display device with high reliability.

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

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

[0010] One embodiment of the present invention is a display device including a light-emitting element and a connection portion. The connection portion is provided along the periphery of a display region where the light-emitting element is provided. The light-emitting element includes a pixel electrode, a first EL layer over the pixel electrode, a second EL layer over the first EL layer, and a common electrode over the second EL layer. The connection portion includes a connection electrode, a second EL layer over the connection electrode, and a common electrode over the second EL layer. The second EL layer includes a first region in contact with the connection electrode and a second region in contact with the common electrode. The area of ​​the region where the first region and the second region overlap in a top view is 40,000 μm 2 The second EL layer has a region with a thickness of 0.5 nm to 1.5 nm, and contains a substance with high electron injection properties.

[0011] Another embodiment of the present invention is a display device including a light-emitting element and a connection portion. The connection portion is provided along the periphery of a display region where the light-emitting element is provided. The light-emitting element includes a pixel electrode, an insulating layer over the pixel electrode, a first EL layer over the pixel electrode and over the insulating layer, a second EL layer over the first EL layer, and a common electrode over the second EL layer. The connection portion includes a connection electrode, an insulating layer over the connection electrode, a second EL layer over the connection electrode and over the insulating layer, and a common electrode over the second EL layer. The second EL layer includes a third region in contact with the connection electrode and a second region in contact with the common electrode through a first opening in the insulating layer. The area of ​​the region where the third region and the second region overlap in a top view is 40,000 μm 2 The second EL layer has a region with a thickness of 0.5 nm to 1.5 nm, and contains a substance with high electron injection properties.

[0012] In the above display device, the first EL layer preferably has a region in contact with the pixel electrode through the second opening of the insulating layer.

[0013] In the above display device, it is preferable that the first EL layer contains a light-emitting compound and the second EL layer contains lithium fluoride.

[0014] In the display device, the connection portion preferably has a comb-like shape or a top surface shape with slits. [Effects of the Invention]

[0015] According to one embodiment of the present invention, a display device that can easily achieve high resolution and a manufacturing method thereof can be provided. Alternatively, a display device that combines high display quality and high resolution can be provided. Alternatively, a display device with high contrast can be provided. Alternatively, a display device with high reliability can be provided.

[0016] According to one embodiment of the present invention, a display device having a novel structure or a manufacturing method of the display device can be provided. Alternatively, a method for manufacturing the display device with high yield can be provided. According to one embodiment of the present invention, at least one of the problems of the prior art can be alleviated.

[0017] 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. [Brief explanation of the drawings]

[0018] 1A to 1C are diagrams showing configuration examples of a display device. 2A to 2J are diagrams showing configuration examples of the display device. 3A to 3C are diagrams showing an example of a method for manufacturing a display device. 4A to 4C are diagrams showing an example of a method for manufacturing a display device. 5A to 5C are diagrams showing an example of a method for manufacturing a display device. 6A to 6D are diagrams showing an example of a method for manufacturing a display device. 7A to 7C are diagrams showing configuration examples of a display device. FIG. 8 is a diagram illustrating an example of the configuration of a display device. 9A to 9C are diagrams showing an example of a method for manufacturing a display device. 10A and 10B are diagrams showing an example of a method for manufacturing a display device. 11A to 11D are diagrams showing configuration examples of a display device. FIG. 12 is a diagram illustrating an example of the configuration of a display device. 13A to 13C are diagrams showing configuration examples of a display device. 14A to 14C are diagrams showing configuration examples of a display device. 15A to 15D are diagrams showing configuration examples of a display device. 16A to 16C are diagrams showing configuration examples of a display device. 17A to 17C are diagrams showing configuration examples of a display device. FIG. 18 is a perspective view showing an example of a display device. 19A and 19B are cross-sectional views showing an example of a display device. 20A is a cross-sectional view showing an example of a display device, and FIG 20B is a cross-sectional view showing an example of a transistor. 21A and 21B are perspective views showing an example of a display module. FIG. 22 is a cross-sectional view showing an example of a display device. FIG. 23 is a cross-sectional view showing an example of a display device. FIG. 24 is a cross-sectional view showing an example of a display device. 25A to 25D are diagrams showing configuration examples of light-emitting elements. 26A and 26B are diagrams showing an example of an electronic device. 27A to 27D are diagrams showing an example of an electronic device. 28A to 28F are diagrams showing an example of an electronic device. 29A to 29F are diagrams showing an example of an electronic device. FIG. 30 is a diagram illustrating the structure of a sample according to an example. FIG. 31 shows the measurement results according to the example. DETAILED DESCRIPTION OF THE INVENTION

[0019] 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.

[0020] 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.

[0021] 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.

[0022] In this specification, ordinal numbers such as "first" and "second" are used to avoid confusion of components and do not limit the number.

[0023] Furthermore, in this specification and the like, the terms "film" and "layer" are interchangeable. For example, the terms "conductive layer" and "insulating layer" may be interchangeable with the terms "conductive film" and "insulating film."

[0024] In this specification, the EL layer refers to a layer that is provided between a pair of electrodes of a light-emitting element and contains at least a light-emitting substance (also referred to as a light-emitting layer), or a stack that includes a light-emitting layer.

[0025] In this specification and the like, a display panel, which is one aspect of a display device, has a function of displaying (outputting) an image or the like on a display surface, and therefore the display panel is one aspect of an output device.

[0026] In addition, in this specification, a display panel having a connector such as an FPC (Flexible Printed Circuit) or TCP (Tape Carrier Package) attached to the substrate, or having an IC mounted on the substrate using a COG (Chip On Glass) method or the like, may be referred to as a display panel module, display module, or simply a display panel.

[0027] In this specification, etc., a device fabricated using a metal mask or 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 FMM may be referred to as a device with an MML (metal maskless) structure.

[0028] In this specification, a structure in which different light-emitting layers are formed or different light-emitting layers are painted for each color light-emitting device (here, blue (B), green (G), and red (R)) may be referred to as an SBS (Side By Side) structure. In this specification, a light-emitting device that can emit white light may be referred to as a white light-emitting device. A white light-emitting device can be combined with a colored layer (for example, a color filter) to realize a full-color display device.

[0029] Light-emitting devices can be broadly divided into single-structure and tandem-structure devices. A single-structure device has one light-emitting unit between a pair of electrodes, and the light-emitting unit preferably includes one or more light-emitting layers. To obtain white light emission, two or more light-emitting layers may be selected so that the light emitted from each of the two or more light-emitting layers has a complementary color relationship. For example, by making the emission color of the first light-emitting layer and the emission color of the second light-emitting layer complementary, a configuration in which the entire light-emitting device emits white light can be obtained. The same applies to light-emitting devices having three or more light-emitting layers.

[0030] A tandem-structured device preferably has two or more light-emitting units between a pair of electrodes, and each light-emitting unit preferably includes one or more light-emitting layers. To obtain white light, light from the light-emitting layers of the multiple light-emitting units may be combined to obtain white light. The configuration for obtaining white light is the same as that of the single-structured device. In a tandem-structured device, it is preferable to provide an intermediate layer such as a charge-generating layer between the multiple light-emitting units.

[0031] Furthermore, when comparing the above-mentioned white light-emitting device (single structure or tandem structure) with a light-emitting device having an SBS structure, the light-emitting device having an SBS structure can reduce power consumption compared to the white light-emitting device. If you want to keep power consumption low, it is preferable to use a light-emitting device having an SBS structure. On the other hand, the manufacturing process of a white light-emitting device is simpler than that of a light-emitting device having an SBS structure, so it is preferable because it can reduce manufacturing costs or increase manufacturing yields.

[0032] In addition, in this specification, when upper and lower limit values ​​are specified, it is also considered that a configuration in which the upper limit values ​​and the lower limit values ​​are freely combined is also disclosed.

[0033] (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.

[0034] 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. The light-emitting element is preferably an organic EL element (organic electroluminescent element). Two or more light-emitting elements that emit different colors each have an EL layer containing a different material. For example, a full-color display device can be realized by having three types of light-emitting elements that emit red (R), green (G), or blue (B) light, respectively.

[0035] Here, when creating separate EL layers for light-emitting elements of different colors, it is known to form them by vapor deposition using a shadow mask such as a metal mask. However, with this method, various factors, such as the accuracy of the metal mask, misalignment between the metal mask and the substrate, deflection of the metal mask, and the spread of the contours of the deposited film due to vapor scattering, can cause deviations in the shape and position of the island-shaped organic film from the design, making it difficult to achieve high resolution and a high aperture ratio. For this reason, measures have been taken to artificially increase the resolution (also known as pixel density) by applying special pixel arrangement methods such as a pentile arrangement.

[0036] 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.

[0037] For simplicity, a case where EL layers for two color light-emitting elements are formed separately will be described. First, a first EL film and a first sacrificial film (also referred to as a mask film) are laminated to cover two pixel electrodes. Next, a resist mask is formed on the first sacrificial film at a position overlapping one of the pixel electrodes (first pixel electrode). Next, the resist mask, a portion of the first sacrificial film, and a portion of the first EL film are etched. At this time, the etching is stopped when the other pixel electrode (second pixel electrode) is exposed. As a result, a portion of the first EL film (also referred to as a first EL layer) processed into a strip or island shape can be formed on the first pixel electrode, and a portion of the sacrificial film (also referred to as a first sacrificial layer) can be formed thereon. Note that in this specification, the term "island-like" refers to a state in which two or more layers made of the same material and formed in the same process are physically separated.

[0038] Next, a second EL film and a second sacrificial film are stacked and formed. Then, a resist mask is formed in a position overlapping the second pixel electrode. Next, as described above, a portion of the second sacrificial film and a portion of the second EL film that do not overlap with the resist mask are etched. As a result, a first EL layer and a first sacrificial layer (also referred to as a mask layer) are provided on the first pixel electrode, and a second EL layer and a second sacrificial layer are provided on the second pixel electrode. In this way, the first EL layer and the second EL layer can be separately formed. Finally, the first sacrificial layer and the second sacrificial layer are removed to expose the first EL layer and the second EL layer, and then a common electrode is formed, thereby separately forming two-color light-emitting elements.

[0039] Furthermore, by repeating the above steps, EL layers for light-emitting elements of three or more colors can be produced separately, and a display device having light-emitting elements of three or four or more colors can be realized.

[0040] Here, in order to supply a potential to the common electrode, an electrode (also referred to as a first electrode, a connection electrode, etc.) can be provided on the same surface as the pixel electrode, and the connection electrode and the common electrode can be electrically connected. The connection electrode is disposed outside the display section where the pixels are provided. Here, in order to prevent the upper surface of the connection electrode from being exposed to etching when the first EL film is etched, it is preferable to provide a first sacrificial layer also on the connection electrode. Similarly, it is preferable to provide a second sacrificial layer on the connection electrode when the second EL film is etched. The first sacrificial layer and the second sacrificial layer provided on the connection electrode can be removed by etching simultaneously with the first sacrificial layer on the first EL layer and the second sacrificial layer on the second EL layer.

[0041] While it is difficult to achieve a spacing of less than 10 μm between EL layers of different colors using a metal mask, the above method allows for a spacing of 3 μm or less, 2 μm or less, or even 1 μm or less. For example, by using an exposure device for LSIs, the spacing can be narrowed to 500 nm or less, 200 nm or less, 100 nm or less, or even 50 nm or less. This significantly reduces the area of ​​the non-light-emitting region that may exist between two light-emitting elements, enabling 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%.

[0042] Furthermore, the pattern of the EL layer itself can be made much smaller than when a metal mask is used. For example, when a metal mask is used to separately create 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. In contrast, the above-described fabrication method forms a pattern 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.

[0043] As described above, the above-described manufacturing method can realize a display device integrating minute light-emitting elements, eliminating the need to artificially increase the resolution by applying a special pixel arrangement method such as a pen-tile method. As a result, 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, or even 3000 ppi or more, or even 5000 ppi or more.

[0044] 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.

[0045] [Configuration example 1] 1A is a schematic top view of a display device 100 according to one embodiment of the present invention. The display device 100 includes a plurality of red light-emitting elements 110R, a plurality of green light-emitting elements 110G, and a plurality of blue light-emitting elements 110B. In FIG. 1A, the light-emitting regions of the light-emitting elements are labeled with R, G, and B to easily distinguish the light-emitting elements from one another.

[0046] The light-emitting elements 110R, 110G, and 110B are arranged in a matrix. Fig. 1A shows a so-called stripe arrangement in which light-emitting elements of the same color are arranged in one direction. However, the arrangement of the light-emitting elements is not limited to this, and other arrangements such as a delta arrangement or a zigzag arrangement may also be used, or a pentile arrangement may also be used.

[0047] The light emitting elements 110R, 110G, and 110B are arranged in the X direction. Furthermore, light emitting elements of the same color are arranged in the Y direction that intersects with the X direction.

[0048] As the light-emitting elements 110R, 110G, and 110B, it is preferable to use EL elements such as OLEDs (organic light-emitting diodes) or QLEDs (quantum-dot light-emitting diodes). Examples of light-emitting materials that the EL elements have include fluorescent materials, phosphorescent materials, and thermally activated delayed fluorescence (TADF materials). As the light-emitting materials that the EL elements have, not only organic compounds but also inorganic compounds (such as quantum dot materials) can be used.

[0049] 1A also shows a connection electrode 111C that is electrically connected to the common electrode 113. The connection electrode 111C is given a potential (for example, an anode potential or a cathode potential) to be supplied to the common electrode 113. The connection electrode 111C is provided outside the display area where the light-emitting elements 110R and the like are arranged. In addition, in FIG. 1A, the common electrode 113 is shown by a dashed line.

[0050] 1B is a schematic cross-sectional view corresponding to the dashed dotted line A1-A2 in FIG. 1A, and FIG. 1C is a schematic cross-sectional view corresponding to the dashed dotted line B1-B2 in FIG. 1A.

[0051] 1B shows cross sections of the light-emitting elements 110R, 110G, and 110B. The light-emitting element 110R has a pixel electrode 111R, an EL layer 112R, an EL layer 114, and a common electrode 113. The light-emitting element 110G has a pixel electrode 111G, an EL layer 112G, an EL layer 114, and a common electrode 113. The light-emitting element 110B has a pixel electrode 111B, an EL layer 112B, an EL layer 114, and a common electrode 113. The EL layer 114 and the common electrode 113 are provided in common to the light-emitting elements 110R, 110G, and 110B. The EL layer 114 can also be referred to as a common layer.

[0052] The EL layer 112R of the light emitting element 110R contains a light emitting organic compound that emits light having an intensity at least in the red wavelength range. The EL layer 112G of the light emitting element 110G contains a light emitting organic compound that emits light having an intensity at least in the green wavelength range. The EL layer 112B of the light emitting element 110B contains a light emitting organic compound that emits light having an intensity at least in the blue wavelength range.

[0053] The EL layer 112R, the EL layer 112G, and the EL layer 112B may each have one or more of an electron injection layer, an electron transport layer, a hole injection layer, and a hole transport layer in addition to a layer containing a light-emitting organic compound (light-emitting layer). The EL layer 114 may not have a light-emitting layer. For example, the EL layer 114 has one or more of an electron injection layer, an electron transport layer, a hole injection layer, and a hole transport layer.

[0054] The pixel electrode 111R, pixel electrode 111G, and pixel electrode 111B are provided for each light-emitting element. The common electrode 113 and EL layer 114 are provided as a continuous layer common to each light-emitting element. A conductive film that is translucent to visible light is used for either one of the pixel electrodes or the common electrode 113, and a conductive film that is reflective to visible light is used for the other. By making each pixel electrode translucent and the common electrode 113 reflective, a bottom-emission display device can be obtained. Conversely, by making each pixel electrode reflective and the common electrode 113 translucent, a top-emission display device can be obtained. Incidentally, by making both the pixel electrodes and the common electrode 113 translucent, a dual-emission display device can also be obtained.

[0055] An insulating layer 131 is provided to cover the edges of the pixel electrode 111R, the pixel electrode 111G, and the pixel electrode 111B. The edges of the insulating layer 131 are preferably tapered. In this specification and the like, a tapered shape refers to a shape in which at least a part of the side surface of a structure is inclined with respect to the substrate surface. For example, it is preferable to have a region in which the angle (also called the taper angle) between the inclined side surface and the substrate surface is less than 90°. If the insulating layer 131 is unnecessary, it does not have to be provided.

[0056] The EL layer 112R, the EL layer 112G, and the EL layer 112B each have a region in contact with the upper surface of the pixel electrode and a region in contact with the surface of the insulating layer 131. In addition, the ends of the EL layer 112R, the EL layer 112G, and the EL layer 112B are located on the insulating layer 131.

[0057] In the following, when describing matters common to the light-emitting element 110R, the light-emitting element 110G, and the light-emitting element 110B, the symbols added to the reference numerals may be omitted and the elements may be described as light-emitting element 110. Similarly, the pixel electrodes 111R, 111G, and 111B may be described as pixel electrodes 111. Similarly, the EL layers 112R, 112G, and 112B may be described as EL layers 112.

[0058] Furthermore, the combination of colors of light emitted by the light emitting element 110 is not limited to the above, and colors such as cyan, magenta, yellow, etc. may also be used. Furthermore, although the above example shows three colors of red (R), green (G), and blue (B), the number of colors of light emitted by the light emitting element 110 included in the display device 100 may be two colors, or four or more colors.

[0059] 1B, a gap is provided between two EL layers 112 between light-emitting elements of different colors. In this manner, it is preferable that the EL layers 112R, 112G, and 112B are provided so as not to contact each other. This makes it possible to preferably prevent current from flowing through two adjacent EL layers 112 and causing unintended light emission. This makes it possible to improve contrast and realize a display device with high display quality.

[0060] As shown in Fig. 1C, in the display region, the EL layer 112R is formed in a strip shape so that the EL layer 112R is continuous in the Y direction. By forming the EL layer 112R and the like in a strip shape, space to separate them is not required, and the area of ​​the non-light-emitting region between the light-emitting elements can be reduced, thereby increasing the aperture ratio. Note that Fig. 1C shows a cross section of the light-emitting element 110R as an example, but the light-emitting element 110G and the light-emitting element 110B can also be formed in a similar shape.

[0061] 1C also shows a connection portion 130 where the connection electrode 111C and the common electrode 113 are electrically connected. In the connection portion 130, the EL layer 114 is provided in contact with the connection electrode 111C, and the common electrode 113 is provided in contact with the EL layer 114. In other words, the connection portion 130 has a structure in which the EL layer 114 is sandwiched between the connection electrode 111C and the common electrode 113. In other words, the EL layer 114 has a first region in contact with the connection electrode 111C and a second region in contact with the common electrode 113. In addition, an insulating layer 131 is provided to cover an end portion of the connection electrode 111C.

[0062] It is preferable to reduce the electrical resistance in the thickness direction of the EL layer 114 by forming the EL layer 114 as thin as possible. For example, the EL layer 114 is made of an electron-injecting or hole-injecting material having a thickness of 0.1 nm or more and less than 2 nm, preferably 0.5 nm or more and 1.5 nm or less, typically about 1.0 nm. The EL layer 114 may be formed of a stacked structure of an electron-injecting layer and an electron-transporting layer, or a stacked structure of a hole-injecting layer and a hole-transporting layer.

[0063] Furthermore, it is preferable to suppress an increase in the electrical resistance between the connection electrode 111C and the common electrode 113 by increasing the area of ​​the region where the connection electrode 111C and the common electrode 113 overlap with each other via the EL layer 114. For example, the area of ​​the region where the connection electrode 111C and the common electrode 113 overlap with each other via the EL layer 114 is set to 10,000 μm 2 (0.01mm 2 ) or more, preferably 20,000 μm 2 (0.02mm 2 ) or more, more preferably 40,000 μm 2 (0.04mm 2) or more. Note that there is no particular upper limit to the area of ​​the region where the connection electrode 111C and the common electrode 113 overlap with each other via the EL layer 114. The area of ​​the region where the connection electrode 111C and the common electrode 113 overlap with each other via the EL layer 114 may be referred to as the contact area. The area of ​​the region where the connection electrode 111C and the common electrode 113 overlap with each other via the EL layer 114 can also be referred to as the area of ​​the region where the first region (the region where the EL layer 114 and the connection electrode 111C contact each other) and the second region (the region where the EL layer 114 and the common electrode 113 contact each other) overlap.

[0064] As a result, the electrical resistance between the connection electrode 111C and the common electrode 113 can be made negligible. Therefore, the connection electrode 111C and the common electrode 113 are electrically connected. When a material with low electrical resistance is used for the EL layer 114, the electrical resistance between the connection electrode 111C and the common electrode 113 can sometimes be made negligible by satisfying either the above-mentioned preferred film thickness of the EL layer 114 or the preferred area of ​​the region where the connection electrode 111C and the common electrode 113 overlap with each other via the EL layer 114.

[0065] The thickness of the EL layer 114 can sometimes be measured by observing the cross-sectional shape of the EL layer 114 and its surroundings using a transmission electron microscope (TEM) or the like. Alternatively, the thickness can sometimes be measured using secondary ion mass spectrometry (SIMS), EDX line analysis, or the like. For example, if the EL layer 114 has an electron injection layer made of lithium fluoride (LiF), the thickness of the EL layer 114 can be measured using the lithium or fluorine concentration (concentration obtained by SIMS) at the interface between the EL layer 112 and the common electrode 113 and in the vicinity thereof. Alternatively, the thickness of the EL layer 114 can be measured using the lithium or fluorine concentration (concentration obtained by SIMS) at the interface between the connection electrode 111C and the common electrode 113 and in the vicinity thereof.

[0066] In addition, the area of ​​the region where the connection electrode 111C and the common electrode 113 overlap via the EL layer 114 may be measured by observing the planar shape of the connection portion and its surrounding area using a scanning transmission electron microscope (STEM) or the like.

[0067] A protective layer 121 is provided on the common electrode 113 to cover the light emitting elements 110R, 110G, and 110B. The protective layer 121 has a function of preventing impurities such as water from diffusing from above into each light emitting element.

[0068] The protective layer 121 may have, for example, a single-layer structure or a multilayer structure including at least an inorganic insulating film. Examples of the inorganic insulating film include oxide films or nitride films such as a silicon oxide film, a silicon oxynitride film, a silicon nitride oxide film, a silicon nitride film, an aluminum oxide film, an aluminum oxynitride film, and a hafnium oxide film. Alternatively, the protective layer 121 may be made of a semiconductor material such as indium gallium oxide or indium gallium zinc oxide.

[0069] 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, 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, or a lens array) is provided above the protective layer 121, the influence of uneven shapes caused by the structure below can be reduced, which is preferable.

[0070] 2A to 2J are schematic top views of a display device 100 according to one embodiment of the present invention. Note that FIG. 1A can also be considered an enlarged view of the area surrounded by the dashed-dotted line in FIG. 2A. The display device 100 includes a display region 105 and a connection portion provided outside the display region 105.

[0071] The display region 105 includes a light-emitting element. The light-emitting element includes a common electrode 113.

[0072] The connection portion has a common electrode 113 and a connection electrode 111C. The connection portion (connection electrode 111C) is provided along the outer periphery of the display area 105. The connection portion may be provided, for example, along one side of the outer periphery of the display area 105, or may be provided over two or more sides of the outer periphery of the display area 105.

[0073] For example, when the top surface shape of the display region 105 is rectangular (including square), the top surface shape of the connection portion (connection electrode 111C) can be rectangular ( FIG. 2A ), strip-shaped ( FIG. 2B ), L-shaped ( FIG. 2C ), or U-shaped (square bracket) ( FIG. 2D ). The top surface shape of the display region 105 is not limited to a rectangle, and may be any quadrangle other than a rectangle. Even when the top surface shape of the display region 105 is quadrangle other than a rectangle, it is preferable to provide the connection portion so as to follow the periphery of the display region 105. In this case, the top surface shape of the connection portion can be strip-shaped, L-shaped, U-shaped (square bracket), V-shaped, or the like.

[0074] The top surface shape of the display region 105 may also be a shape other than the above. For example, the top surface shape of the display region 105 may be a polygon other than a rectangle. FIG. 2E shows an example in which the top surface shape of the display region 105 is a regular octagon, and FIG. 2F shows an example in which the top surface shape of the display region 105 is a regular dodecagon. Note that while FIGS. 2E and 2F show examples in which the top surface shape of the display region 105 is a regular polygon, the top surface shape of the display region 105 may also be a non-regular polygon, a regular polygon with rounded corners, or a polygon with rounded corners. FIG. 2G shows an example in which the top surface shape of the display region 105 is an octagon. Even when the top surface shape of the display region 105 is polygonal, it is preferable to provide a connection portion (connection electrode 111C) along the outer periphery of the display region 105. In this case, the top surface shape of the connection portion may be a strip shape, an L-shape, a U-shape (square bracket shape), a V-shape, or the like.

[0075] Furthermore, the top surface shape of display region 105 may be a curved shape (including a circle, an ellipse, an oval, etc.). FIG. 2H shows an example in which the top surface shape of display region 105 is a circle. Even when the top surface shape of display region 105 is a polygon, it is preferable to provide a connection portion (connection electrode 111C) along the periphery of display region 105. In this case, the top surface shape of the connection portion may be a circle, a C-shape, a U-shape, a strip-shape, an L-shape, a U-shape (square bracket shape), a V-shape, etc.

[0076] Figures 2I and 2J show enlarged views of the area surrounded by the dashed line in Figure 2E. When the top surface shape of display area 105 is a quadrangle, polygon, curved shape, or the like other than a rectangle, the edges of display area 105 and connection electrode 111C may be straight or curved as shown in Figure 2I, or may be stepped as shown in Figure 2J.

[0077] The common electrode 113 of the light emitting element and the connection portion is preferably provided so as to encompass the display region 105 and the connection electrode 111C. In this case, the common electrode 113 has a region that overlaps with the connection electrode 111C.

[0078] [Production method example 1] An example of a method for manufacturing a display device according to one embodiment of the present invention will be described below with reference to the drawings. Here, the display device 100 shown in the above-described configuration example will be used as an example. FIGS. 3A to 6D are cross-sectional schematic views illustrating steps in the manufacturing method of a display device, which will be described below. In FIG. 3A and other drawings, a cross-sectional schematic view of a portion indicated by a dashed line A1-A2 in FIG. 1A is shown on the left side, and a cross-sectional schematic view of a portion indicated by a dashed line B1-B2 in FIG. 1A is shown on the right side.

[0079] The thin films (insulating films, semiconductor films, conductive films, etc.) that make up the display device can be formed using methods such as sputtering, chemical vapor deposition (CVD), vacuum evaporation, pulsed laser deposition (PLD), and atomic layer deposition (ALD). CVD methods include plasma enhanced chemical vapor deposition (PECVD) and thermal CVD. Metal organic chemical vapor deposition (MOCVD) is one type of thermal CVD.

[0080] Furthermore, thin films (insulating films, semiconductor films, conductive films, etc.) that constitute 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, and knife coating.

[0081] Furthermore, when processing the thin film that constitutes the display device, a photolithography method or the like can be used. Alternatively, the thin film may be processed by a nanoimprint method, a sandblasting method, a lift-off method, or the like. Furthermore, the island-shaped thin film may be directly formed by a film formation method using a shielding mask such as a metal mask.

[0082] There are two typical photolithography methods: one is to form a resist mask on the thin film to be processed, process the thin film by etching or the like, and then remove the resist mask; the other is to form a photosensitive thin film, and then process the thin film into the desired shape by exposure and development.

[0083] In photolithography, the light used for exposure can be, for example, i-line (wavelength 365 nm), g-line (wavelength 436 nm), h-line (wavelength 405 nm), or a mixture of these. Other light sources that can be used include ultraviolet light, KrF laser light, and ArF laser light. Exposure can also be performed using immersion exposure technology. Light sources that can be used for exposure include extreme ultraviolet (EUV) light, X-rays, and the like. Electron beams can also be used instead of light for exposure. Extreme ultraviolet light, X-rays, or electron beams 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.

[0084] For etching the thin film, dry etching, wet etching, sandblasting, or the like can be used.

[0085] [Preparation of Substrate 101] A substrate having heat resistance sufficient to withstand at least a subsequent heat treatment can be used as the substrate 101. When an insulating substrate is used as the substrate 101, a glass substrate, a quartz substrate, a sapphire substrate, a ceramic substrate, an organic resin substrate, or the like can be used. Also, a semiconductor substrate such as a single crystal semiconductor substrate made of silicon, silicon carbide, or the like, a polycrystalline semiconductor substrate, a compound semiconductor substrate such as silicon germanium, or an SOI substrate can be used.

[0086] In particular, it is preferable to use a substrate in which a semiconductor circuit including semiconductor elements such as transistors is formed on the semiconductor substrate or insulating substrate as the substrate 101. The semiconductor circuit preferably constitutes, for example, a pixel circuit, a gate line driving circuit (gate driver), a source line driving circuit (source driver), etc. In addition to the above, an arithmetic circuit, a memory circuit, etc. may also be configured.

[0087] [Formation of pixel electrodes 111R, 111G, 111B, and connection electrode 111C] Next, the pixel electrodes 111R, 111G, 111B, and the connection electrode 111C are formed on the substrate 101. First, a conductive film that will become the pixel electrodes and the connection electrode is formed, a resist mask is formed by photolithography, and unnecessary portions of the conductive film are removed by etching. After that, the resist mask is removed, thereby forming the pixel electrodes 111R, 111G, 111B, and the connection electrode 111C.

[0088] When a conductive film reflective to visible light is used as each pixel electrode, it is preferable to use a material (such as silver or aluminum) with as high a 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.

[0089] [Formation of insulating layer 131] Next, an insulating layer 131 is formed to cover the edges of the pixel electrode 111R, pixel electrode 111G, pixel electrode 111B, and connection electrode 111C (FIG. 3A). An organic insulating film or an inorganic insulating film can be used as the insulating layer 131. The insulating layer 131 preferably has tapered edges to improve the step coverage of the EL film that will be formed later. In particular, when an organic insulating film is used, it is preferable to use a photosensitive material, as this makes it easier to control the shape of the edges by adjusting the exposure and development conditions.

[0090] [Formation of EL film 112Rf] Subsequently, an EL film 112Rf, which will later become the EL layer 112R, is formed on the pixel electrodes 111R, 111G, 111B, and insulating layer 131.

[0091] The EL film 112Rf includes a film containing at least a light-emitting compound. Alternatively, the EL film 112Rf may include one or more layers functioning as an electron injection layer, an electron transport layer, a charge generation layer, a hole transport layer, or a hole injection layer. The EL film 112Rf can be formed by, for example, a vapor deposition method, a sputtering method, or an inkjet method. However, the method is not limited to these, and the above-described film formation methods can be used as appropriate.

[0092] As an example, the EL film 112Rf is preferably a stacked film in which a hole injection layer, a hole transport layer, a light-emitting layer, and an electron transport layer are stacked in this order. In this case, a film having an electron injection layer can be used as the EL layer 114 to be formed later. In particular, providing an electron transport layer to cover the light-emitting layer can prevent the light-emitting layer from being damaged in a subsequent photolithography process, thereby enabling the fabrication of a highly reliable light-emitting element. Furthermore, using layers containing the same organic compound for the electron transport layer used in the EL film 112Rf and the electron injection layer used in the subsequent EL layer 114 improves the bonding between them, resulting in a light-emitting element with high luminous efficiency and reliability. For example, an organic compound with electron transport properties can be used for the electron transport layer, and a material containing the organic compound and a metal can be used for the electron injection layer.

[0093] It is preferable that the EL film 112Rf is formed so as not to be provided on the connection electrode 111C. For example, when the EL film 112Rf is formed by vapor deposition (or sputtering), it is preferable to form it using a shielding mask so that the EL film 112Rf is not formed on the connection electrode 111C.

[0094] [Formation of Sacrificial Film 144a] Subsequently, a sacrificial film 144a is formed to cover the EL film 112Rf. The sacrificial film 144a is provided in contact with the upper surface of the connection electrode 111C.

[0095] The sacrificial film 144a can be a film that is highly resistant to the etching process of each EL film, such as the EL film 112Rf, i.e., a film with a large etching selectivity. The sacrificial film 144a can also be a film that has a large etching selectivity with respect to a protective film, such as the protective film 146a described below. Furthermore, the sacrificial film 144a can be a film that can be removed by wet etching, which causes little damage to each EL film.

[0096] The sacrificial film 144a may be, for example, a metal film, an alloy film, a metal oxide film, a semiconductor film, or an inorganic insulating film. The sacrificial film 144a may be formed by various film formation methods, such as sputtering, vapor deposition, CVD, and ALD. The sacrificial film 144a is preferably formed by a method that causes as little damage as possible to the underlying layer (especially the EL film 112Rf, etc.). For example, the sacrificial film 144a can be preferably formed by ALD or vacuum vapor deposition. Furthermore, the ALD method can cause less damage to the underlying layer than the sputtering method.

[0097] The sacrificial film 144a may be made of a metal material such as gold, silver, platinum, magnesium, nickel, tungsten, chromium, molybdenum, iron, cobalt, copper, palladium, titanium, aluminum, yttrium, zirconium, or tantalum, or an alloy material containing such a metal material. In particular, it is preferable to use a low-melting-point material such as aluminum or silver.

[0098] The sacrificial film 144a may be made of a metal oxide such as indium gallium zinc oxide (In-Ga-Zn oxide, also referred to as IGZO). Other examples include indium oxide, indium zinc oxide (In-Zn oxide), indium tin oxide (In-Sn oxide), indium titanium oxide (In-Ti oxide), indium tin zinc oxide (In-Sn-Zn oxide), indium titanium zinc oxide (In-Ti-Zn oxide), and indium gallium tin zinc oxide (In-Ga-Sn-Zn oxide). Alternatively, silicon-containing indium tin oxide may be used.

[0099] Instead of the gallium, an element M (wherein M is one or more elements selected from aluminum, silicon, boron, yttrium, copper, vanadium, beryllium, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, and magnesium) may be used. In particular, it is preferable that M is one or more elements selected from gallium, aluminum, and yttrium.

[0100] The sacrificial film 144a can be made of an inorganic insulating material such as aluminum oxide, hafnium oxide, or silicon oxide. Aluminum oxide is particularly suitable for use as the sacrificial film 144a because it can reduce manufacturing costs. Furthermore, forming an aluminum oxide film using the ALD method is also suitable for the sacrificial film 144a because it can reduce damage to the underlying layer (particularly the EL film 112Rf).

[0101] The sacrificial film 144a may have a single layer structure or a laminated structure of two or more layers. Typical examples of the laminated structure include a two-layer structure of an In-Ga-Zn oxide film formed by sputtering and a silicon nitride film formed by sputtering, a two-layer structure of an In-Ga-Zn oxide film formed by sputtering and an aluminum oxide film formed by ALD, or a two-layer structure of an aluminum oxide film formed by ALD and an In-Ga-Zn oxide film formed by sputtering.

[0102] Note that when forming the sacrificial film 144a by the ALD method or the sputtering method, the film may be heated. In this case, the substrate temperature during the formation of the sacrificial film 144a is preferably within a range that does not deteriorate the base material (here, the EL film 112Rf), and may be set to a temperature between room temperature and 200°C, preferably between 50°C and 150°C, more preferably between 70°C and 100°C, and typically around 80°C. This configuration can improve the adhesion between the base material and the sacrificial film 144a.

[0103] Furthermore, it is preferable to use a material that can dissolve in a chemically stable solvent for the sacrificial film 144a, at least for the film located at the top of the EL film 112Rf. In particular, a material that dissolves in water or alcohol is suitable for use in the sacrificial film 144a. When forming the sacrificial film 144a, it is preferable to apply the material dissolved in a solvent such as water or alcohol using a wet film-forming method, and then perform a heat treatment to evaporate the solvent. In this case, performing the heat treatment under a reduced pressure atmosphere is preferable because it allows the solvent to be removed at a low temperature and in a short time, thereby reducing thermal damage to the EL film 112Rf.

[0104] Wet film formation methods that can be used to form the sacrificial film 144a include spin coating, dipping, spray coating, inkjet, dispensing, screen printing, offset printing, doctor knife method, slit coating, roll coating, curtain coating, and knife coating.

[0105] The sacrificial film 144a may be made of an organic material such as polyvinyl alcohol (PVA), polyvinyl butyral, polyvinyl pyrrolidone, polyethylene glycol, polyglycerin, pullulan, water-soluble cellulose, or alcohol-soluble polyamide resin.

[0106] [Formation of protective film 146a] Subsequently, a protective film 146a is formed on the sacrificial film 144a (FIG. 3B).

[0107] The protective film 146a is a film that is used as a hard mask when etching the sacrificial film 144a later. Furthermore, when processing the protective film 146a later, the sacrificial film 144a is exposed. Therefore, a combination of films that have a large etching selectivity relative to each other is selected for the sacrificial film 144a and the protective film 146a. Therefore, a film that can be used for the protective film 146a can be selected depending on the etching conditions for the sacrificial film 144a and the etching conditions for the protective film 146a.

[0108] For example, when dry etching using a gas containing fluorine (also called a fluorine-based gas) is used to etch the protective film 146a, silicon, silicon nitride, silicon oxide, tungsten, titanium, molybdenum, tantalum, tantalum nitride, an alloy containing molybdenum and niobium, an alloy containing molybdenum and tungsten, etc. can be used for the protective film 146a. Here, metal oxide films such as IGZO and ITO can be used as films that can have a large etching selectivity (i.e., can slow down the etching rate) compared to dry etching using the fluorine-based gas, and these can be used for the sacrificial film 144a.

[0109] However, the protective film 146a is not limited to this, and can be selected from various materials depending on the etching conditions of the sacrificial film 144a and the etching conditions of the protective film 146a. For example, it can be selected from the films that can be used for the sacrificial film 144a.

[0110] The protective film 146a may be, for example, a nitride film, such as silicon nitride, aluminum nitride, hafnium nitride, titanium nitride, tantalum nitride, tungsten nitride, gallium nitride, or germanium nitride.

[0111] Alternatively, an oxide film or an oxynitride film can be used as the protective film 146a. Typically, an oxide film or an oxynitride film such as silicon oxide, silicon oxynitride, aluminum oxide, aluminum oxynitride, hafnium oxide, or hafnium oxynitride can be used.

[0112] Alternatively, the protective film 146a may be an organic film that can be used for the EL film 112Rf, etc. For example, the same organic film as that used for the EL film 112Rf, the EL film that will become the EL layer 112G, or the EL film that will become the EL layer 112B can be used for the protective film 146a. Using such an organic film is preferable because it allows the same film-forming equipment to be used for the EL film 112Rf, etc.

[0113] [Formation of resist mask 143a] Subsequently, resist masks 143a are formed on the protective film 146a at positions overlapping the pixel electrode 111R and the connection electrode 111C (FIG. 3C).

[0114] 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.

[0115] If the resist mask 143a is formed on the sacrificial film 144a without the protective film 146a, the EL film 112Rf may be dissolved by the solvent of the resist material if the sacrificial film 144a has defects such as pinholes. The use of the protective film 146a can prevent such problems.

[0116] When the sacrificial film 144a is made of a film that is less likely to have defects such as pinholes, the resist mask 143a may be formed directly on the sacrificial film 144a without using the protective film 146a.

[0117] [Etching of the protective film 146a] Subsequently, a part of the protective film 146a that is not covered by the resist mask 143a is removed by etching to form a protective layer 147a. At the same time, the protective layer 147a is also formed on the connection electrode 111C.

[0118] When etching the protective film 146a, it is preferable to use etching conditions with a high selectivity so that the sacrificial film 144a is not removed by the etching. The protective film 146a can be etched by wet etching or dry etching, but using dry etching can prevent the pattern of the protective film 146a from shrinking.

[0119] [Removal of resist mask 143a] Subsequently, the resist mask 143a is removed (FIG. 4A).

[0120] The resist mask 143a can be removed by wet etching or dry etching. In particular, the resist mask 143a is preferably removed by dry etching (also called plasma ashing) using oxygen gas as an etching gas.

[0121] At this time, the resist mask 143a is removed while the EL film 112Rf is covered with the sacrificial film 144a, so that the influence on the EL film 112Rf is suppressed. In particular, if the EL film 112Rf comes into contact with oxygen, it may have an adverse effect on the electrical characteristics, so this is suitable for performing etching using oxygen gas, such as plasma ashing.

[0122] [Etching of the sacrificial film 144a] Next, using the protective layer 147a as a mask, a portion of the sacrificial film 144a that is not covered by the protective layer 147a is removed by etching to form a sacrificial layer 145a (FIG. 4B). At the same time, the sacrificial layer 145a is also formed on the connection electrode 111C.

[0123] The sacrificial film 144a can be etched by wet etching or dry etching, but dry etching is preferable because it can prevent the pattern from shrinking.

[0124] [Etching of EL film 112Rf and protective layer 147a] Subsequently, the protective layer 147a is etched, and at the same time, a portion of the EL film 112Rf that is not covered by the sacrificial layer 145a is removed by etching to form a strip-shaped EL layer 112R (FIG. 4C). At this time, the protective layer 147a on the connection electrode 111C is also removed.

[0125] Etching the EL film 112Rf and the protective layer 147a in the same process is preferable because it simplifies the process and reduces the manufacturing cost of the display device.

[0126] In particular, dry etching using an etching gas that does not contain oxygen as a main component is preferable for etching the EL film 112Rf. This suppresses deterioration of the EL film 112Rf and realizes a highly reliable display device. Examples of etching gases that do not contain oxygen as a main component include noble gases such as CF4, C4F8, SF6, CHF3, Cl2, H2O, BCl3, H2, and He. Alternatively, a mixture of any of the above gases and a diluent gas that does not contain oxygen can be used as the etching gas.

[0127] The EL film 112Rf and the protective layer 147a may be etched separately. In this case, the EL film 112Rf may be etched first, or the protective layer 147a may be etched first.

[0128] At this point, the EL layer 112R and the connection electrode 111C are covered with the sacrificial layer 145a.

[0129] [Formation of EL film 112Gf] Subsequently, an EL film 112Gf, which will later become the EL layer 112G, is formed on the sacrificial layer 145a, the insulating layer 131, the pixel electrode 111G, and the pixel electrode 111B. At this time, similar to the EL film 112Rf, it is preferable that the EL film 112Gf is not provided on the connection electrode 111C.

[0130] The method for forming the EL film 112Gf can be similar to that described for the EL film 112Rf.

[0131] [Formation of Sacrificial Film 144b] Next, a sacrificial film 144b is formed on the EL film 112Gf. The sacrificial film 144b can be formed by the same method as the sacrificial film 144a. In particular, it is preferable that the sacrificial film 144b is made of the same material as the sacrificial film 144a.

[0132] At the same time, a sacrificial film 144b is formed on the connection electrode 111C, covering the sacrificial layer 145a.

[0133] [Formation of protective film 146b] Next, the protective film 146b is formed on the sacrificial film 144b. The protective film 146b can be formed by the same method as the protective film 146a. In particular, it is preferable that the protective film 146b is made of the same material as the protective film 146a.

[0134] [Formation of resist mask 143b] Subsequently, a resist mask 143b is formed on the protective film 146b in an area overlapping with the pixel electrode 111G and an area overlapping with the connection electrode 111C (FIG. 5A).

[0135] The resist mask 143b can be formed in a manner similar to that for the resist mask 143a.

[0136] [Etching of protective film 146b] Subsequently, a portion of the protective film 146b that is not covered by the resist mask 143b is removed by etching to form a protective layer 147b (FIG. 5B). At the same time, the protective layer 147b is also formed on the connection electrode 111C.

[0137] The above description of the protective film 146a can be applied to the etching of the protective film 146b.

[0138] [Removal of resist mask 143b] Next, the resist mask 143b is removed. The above description of the resist mask 143a can be applied to the removal of the resist mask 143b.

[0139] [Etching of the sacrificial film 144b] Next, using the protective layer 147b as a mask, a portion of the sacrificial film 144b that is not covered by the protective layer 147b is removed by etching to form a sacrificial layer 145b. At the same time, a sacrificial layer 145b is also formed on the connection electrode 111C. The sacrificial layer 145a and the sacrificial layer 145b are stacked on the connection electrode 111C.

[0140] The above description of the sacrificial film 144a can be applied to the etching of the sacrificial film 144b.

[0141] [Etching of EL film 112Gf and protective layer 147b] Subsequently, the protective layer 147b is etched, and at the same time, a portion of the EL film 112Gf that is not covered by the sacrificial layer 145b is removed by etching to form a strip-shaped EL layer 112G (FIG. 5C). At this time, the protective layer 147b on the connection electrode 111C is also removed.

[0142] The above description of the EL film 112Rf and the protective layer 147a can be applied to the etching of the EL film 112Gf and the protective layer 147b.

[0143] At this time, since the EL layer 112R is protected by the sacrificial layer 145a, it is possible to prevent the EL film 112Gf from being damaged during the etching process.

[0144] In this way, the strip-shaped EL layers 112R and the strip-shaped EL layers 112G can be formed with high positional accuracy.

[0145] [Formation of EL layer 112B] By performing the above steps on the EL film that will become the EL layer 112B, it is possible to form the island-shaped EL layer 112B and the island-shaped sacrificial layer 145c (FIG. 6A).

[0146] That is, after the EL layer 112G is formed, an EL film that will become the EL layer 112B, a sacrificial film that will become the sacrificial layer 145c, a protective film, and a resist mask are formed in this order. Next, the protective film is etched to form a protective layer, and then the resist mask is removed. Next, the sacrificial film is etched to form the sacrificial layer 145c. Then, the protective layer and the EL film are etched to form the strip-shaped EL layer 112B.

[0147] After the EL layer 112B is formed, the sacrificial layer 145c is also formed on the connection electrode 111C at the same time. The sacrificial layer 145a, the sacrificial layer 145b, and the sacrificial layer 145c are stacked on the connection electrode 111C.

[0148] [Removal of Sacrificial Layer] Next, the sacrificial layers 145a, 145b, and 145c are removed to expose the upper surfaces of the EL layers 112R, 112G, and 112B (FIG. 6B), and at the same time, the upper surface of the connection electrode 111C is also exposed.

[0149] The sacrificial layers 145a, 145b, and 145c can be removed by wet etching or dry etching. It is preferable to use a method that minimizes damage to the EL layers 112R, 112G, and 112B. It is particularly preferable to use a wet etching method. For example, it is preferable to use wet etching using a tetramethylammonium hydroxide solution (TMAH), dilute hydrofluoric acid, oxalic acid, phosphoric acid, acetic acid, nitric acid, or a mixture thereof.

[0150] Alternatively, the sacrificial layers 145a, 145b, and 145c are preferably removed by dissolving them in a solvent such as water or alcohol. Here, various alcohols such as ethyl alcohol, methyl alcohol, isopropyl alcohol (IPA), or glycerin can be used as the alcohol capable of dissolving the sacrificial layers 145a, 145b, and 145c.

[0151] After removing the sacrificial layers 145a, 145b, and 145c, it is preferable to perform a drying treatment to remove water contained inside the EL layers 112R, 112G, and 112B and water adsorbed on their surfaces. For example, it is preferable to perform a heat treatment in an inert gas atmosphere or a reduced-pressure atmosphere. The heat treatment can be performed at a substrate temperature of 50°C or higher and 200°C or lower, preferably 60°C or higher and 150°C or lower, and more preferably 70°C or higher and 120°C or lower. A reduced-pressure atmosphere is preferable because it allows drying at a lower temperature.

[0152] In this manner, the EL layer 112R, the EL layer 112G, and the EL layer 112B can be separately produced.

[0153] [Formation of EL layer 114 and common electrode 113] Next, the EL layer 114 and the common electrode 113 are formed in this order, covering the EL layer 112R, the EL layer 112G, and the EL layer 112B (FIG. 6C). At this time, the EL layer 114 and the common electrode 113 are formed using the same masking mask or without using a masking mask. This reduces manufacturing costs compared to when different masking masks are used. The EL layer 114 and the common electrode 113 are also formed on the connection electrode 111C.

[0154] The EL layer 114 can be formed in the same manner as the EL film 112Rf.

[0155] The common electrode 113 can be formed by a film formation method such as evaporation or sputtering, or by stacking a film formed by evaporation and a film formed by sputtering.

[0156] 6C, the connection portion 130 has a configuration in which the EL layer 114 is sandwiched between the connection electrode 111C and the common electrode 113. As described above, the thickness of the EL layer 114 can be set to, for example, 0.1 nm or more and less than 2 nm, preferably 0.5 nm or more and 1.5 nm or less, and typically about 1.0 nm, thereby reducing the electrical resistance of the EL layer 114 in the thickness direction.

[0157] Furthermore, as described above, by increasing the area of ​​the region where the connection electrode 111C and the common electrode 113 overlap with the EL layer 114 interposed therebetween, an increase in the electrical resistance between the connection electrode 111C and the common electrode 113 can be suppressed.

[0158] As a result, the electrical resistance between the connection electrode 111C and the common electrode 113 can be made negligible, and therefore the connection electrode 111C and the common electrode 113 are electrically connected.

[0159] [Formation of protective layer 121] Next, a protective layer 121 is formed on the common electrode 113. At this time, as shown in FIG. 6D, it is preferable that the protective layer 121 is provided so as to cover the edge of the common electrode 113 and the edge of the EL layer 114. This makes it possible to effectively prevent impurities such as water or oxygen from diffusing from the outside into the EL layer 114 and into the interface between the EL layer 114 and the common electrode 113.

[0160] The inorganic insulating film used for the protective layer 121 is preferably formed by sputtering, PECVD, or ALD. The ALD method is particularly preferred because it has excellent step coverage and is less likely to cause defects such as pinholes. The inkjet method is also preferred for forming the organic insulating film, as it allows for the formation of a uniform film in the desired area.

[0161] In this manner, the display device 100 shown in FIGS. 1B and 1C can be fabricated.

[0162] In the above description, the common electrode 113 and the EL layer 114 are formed in the same region, but they may be formed to have different top surface shapes.

[0163] This completes the description of the example of the method for manufacturing the display device.

[0164] [Configuration example 2] The following describes a configuration example of a display device that is partially different from the above-described configuration example 1. In the following, descriptions of parts that overlap with the above-described configuration example may be omitted.

[0165] The display device 100A shown in FIGS. 7A to 7C differs from the display device 100 described above mainly in that the shapes of the EL layer 114 and the common electrode 113 are different.

[0166] 7B, in the cross section in the X direction, the EL layer 114 and the common electrode 113 are separated between two light-emitting elements 110 that emit light of different colors. In other words, the EL layer 114 and the common electrode 113 have ends at the portions that overlap with the insulating layer 131.

[0167] The protective layer 121 is provided to cover the side surfaces of the EL layer 112, the EL layer 114, and the common electrode 113 in the region where it overlaps with the insulating layer 131.

[0168] 7B, a recess may be formed in a part of the upper surface of insulating layer 131. In this case, it is preferable that protective layer 121 is provided in contact with the surface of the recess in insulating layer 131. This increases the contact area between insulating layer 131 and protective layer 121, which is preferable because it improves adhesion therebetween.

[0169] 7A, the outlines of the common electrode 113 and the EL layer 114 are indicated by dashed lines. As shown in FIG 7A, the common electrode 113 and the EL layer 114 have an upper surface shape that is comb-shaped or has slits.

[0170] Note that, although the display device 100A shown in Fig. 7A has a configuration in which the common electrode 113 and the EL layer 114 are provided so as to overlap with the connection electrode 111C, this is not limiting. For example, as in the display device 100B shown in Fig. 8, the display device 100A may have a configuration in which a portion of the common electrode 113 and the EL layer 114 are provided so as to overlap with the connection electrode 111C. In Fig. 8, the area in which the common electrode 113 and the EL layer 114 overlap with the connection electrode 111C is indicated by hatching.

[0171] [Production method example 2] An example of a method for manufacturing the display device 100A will be described below. Note that, in the following, parts that overlap with the above-mentioned manufacturing method example 1 will be referred to and will not be described again. The manufacturing method example exemplified here differs from the above-mentioned manufacturing method example 1 in the steps subsequent to the step of forming the common electrode 113.

[0172] 9A to 10A show schematic cross-sectional views in each step exemplified below. In addition, in Fig. 9A etc., a schematic cross-sectional view of the portion indicated by the dashed line A1-A2 in Fig. 7A is shown on the left side, and a schematic cross-sectional view of the portion indicated by the dashed line B1-B2 in Fig. 7A is shown on the right side.

[0173] Similar to the above-mentioned manufacturing method example 1, the steps are carried out in order up to the formation of the common electrode 113 (FIG. 9A).

[0174] Next, a plurality of resist masks 143d are formed on the common electrode 113 (FIG. 9B). The resist masks 143d are formed to have a comb-like shape or a top surface shape with slits. The resist masks 143d overlap with the pixel electrodes 111R, 111G, 111B, and the connection electrode 111C. In addition, the resist masks 143d have ends on the insulating layer 131.

[0175] Next, the portions of the common electrode 113 and the EL layer 114 that are not covered by the resist mask 143d are removed by etching (FIG. 9C). As a result, slits are formed by the etching in the common electrode 113 and the EL layer 114, which had previously been provided continuously and covering all the pixel electrodes and connection electrodes, and the common electrode 113 and the EL layer 114 are formed to have a comb-like shape or a top surface shape with slits.

[0176] The etching is preferably performed by dry etching. For example, it is preferable to sequentially etch the common electrode 113, the EL layer 114, and the like by switching the etching gas without exposing them to the air. Furthermore, it is preferable to use a gas that does not contain oxygen as a main component as the etching gas.

[0177] When etching the common electrode 113, the EL layer 114, etc., a part of the insulating layer 131 may be etched, and as shown in Fig. 9C, a recess may be formed in the upper part of the insulating layer 131. Alternatively, a part of the insulating layer 131 that is not covered by the resist mask 143d may be etched, and may be divided into two parts.

[0178] Subsequently, the resist mask 143d is removed by wet etching or dry etching.

[0179] Next, the protective layer 121 is formed (FIG. 10A). The protective layer 121 is provided so as to cover the side surfaces of the common electrode 113, the EL layer 114, and the EL layer 112. The protective layer 121 is preferably provided in contact with the upper surface of the insulating layer 131.

[0180] 10B, when the protective layer 121 is formed, a void (also referred to as a gap or space) 122 may be formed above the insulating layer 131. The void 122 may be under reduced pressure or atmospheric pressure. The void 122 may contain a gas such as air, nitrogen, or a noble gas, or a film-forming gas used to form the protective layer 121.

[0181] This concludes the description of an example of a method for manufacturing the display device 100A.

[0182] Note that although the resist mask 143d is formed directly on the common electrode 113 here, a film functioning as a hard mask may be provided on the common electrode 113. In this case, a hard mask is formed using the resist mask 143d as a mask, and after the resist mask is removed, the common electrode 113, the EL layer 114, and the like can be etched using the hard mask as a mask. Note that the hard mask may be removed or left.

[0183] [Configuration example 3] 11A to 11D differs from the display device 100 described above mainly in the shapes of the EL layer 114 and the common electrode 113. Note that Fig. 11A is a schematic top view of the display device of the region surrounded by the two-dot chain line in Fig. 2A.

[0184] 11C, in the cross section in the Y direction, the EL layer 112R, the EL layer 114, and the common electrode 113 are separated between the two light-emitting elements 110R. In other words, the EL layer 112R, the EL layer 114, and the common electrode 113 have ends at the portions overlapping with the insulating layer 131.

[0185] The protective layer 121 is provided to cover the side surfaces of the EL layer 112R, the EL layer 114, and the common electrode 113 in the region where it overlaps with the insulating layer 131.

[0186] 11C, a recess may be formed in a part of the upper surface of insulating layer 131. In this case, it is preferable that protective layer 121 is provided in contact with the surface of the recess in insulating layer 131. This increases the contact area between insulating layer 131 and protective layer 121, which is preferable because it improves adhesion therebetween.

[0187] In Fig. 11A, the outlines of the common electrode 113 and the EL layer 114 are indicated by dashed lines. As shown in Fig. 11A, the common electrode 113 and the EL layer 114 have a comb-like or slit-like top surface shape. On the other hand, as shown in Figs. 11B and 11C, the EL layer 112R has an island-like shape. Note that, as shown in Fig. 11D, the connection portion 130 has the same configuration as the connection portion 130 of the display device 100.

[0188] 11A has a configuration in which the common electrode 113 and the EL layer 114 are provided so as to overlap with the connection electrode 111C, but this is not limiting. For example, as in the display device 100D shown in Fig. 12, the display device 100C may have a configuration in which a portion of the common electrode 113 and the EL layer 114 are provided so as to overlap with the connection electrode 111C. In Fig. 12, the area in which the common electrode 113 and the EL layer 114 overlap with the connection electrode 111C is indicated by hatching.

[0189] Although not shown here, the light emitting element 110G and the light emitting element 110B can also have a similar configuration.

[0190] [Variations] An example in which the configuration differs in part from that described above will be described below. Note that the same parts as those described above will be used hereinafter, and explanations thereof will be omitted.

[0191] [Variation 1] A display device 100E shown in FIGS. 13A and 13B differs from the display device 100 described above mainly in that the configuration of the light-emitting elements is different.

[0192] The light-emitting element 110R has an optical adjustment layer 115R between the pixel electrode 111R and the EL layer 112R. The light-emitting element 110G has an optical adjustment layer 115G between the pixel electrode 111G and the EL layer 112G. The light-emitting element 110B has an optical adjustment layer 115B between the pixel electrode 111B and the EL layer 112B.

[0193] Furthermore, optical adjustment layer 115R, optical adjustment layer 115G, and optical adjustment layer 115B are each translucent to visible light. Optical adjustment layer 115R, optical adjustment layer 115G, and optical adjustment layer 115B have different thicknesses. This allows the optical path length to be different for each light-emitting element.

[0194] Here, the pixel electrodes 111R, 111G, and 111B are made of conductive films that are reflective to visible light, and the common electrode 113 is made of a conductive film that is reflective and transparent to visible light. This allows each light-emitting element to have a so-called microcavity structure (a microresonator structure), which intensifies light of a specific wavelength. This makes it possible to realize a display device with improved color purity.

[0195] Each optical adjustment layer can be made of a conductive material that is transparent to visible light, such as indium oxide, indium tin oxide, indium zinc oxide, zinc oxide, zinc oxide containing gallium, indium tin oxide containing silicon, or indium zinc oxide containing silicon.

[0196] Each optical adjustment layer can be formed after forming the pixel electrode 111R, the pixel electrode 111G, and the pixel electrode 111B, and before forming the EL film 112Rf, etc. Each optical adjustment layer may use a conductive film having a different thickness, or may have a single-layer structure, a two-layer structure, a three-layer structure, etc., in order from thinnest to thinnest.

[0197] 13C shows a display device 100F in which an optical adjustment layer is applied to the display device 100A. FIG. 13C shows a cross section of three light-emitting elements (light-emitting element 110R, light-emitting element 110G, and light-emitting element 110B) arranged side by side in the X direction.

[0198] [Variation 2] The display device 100G shown in FIGS. 14A and 14B differs from the display device 100E described above mainly in that it does not have an optical adjustment layer.

[0199] The display device 100G is an example in which a microcavity structure is realized by the thicknesses of the EL layer 112R, the EL layer 112G, and the EL layer 112B. With this configuration, there is no need to provide a separate optical adjustment layer, which simplifies the process.

[0200] For example, in display device 100G, EL layer 112R of light emitting element 110R emitting light with the longest wavelength is the thickest, and EL layer 112B of light emitting element 110B emitting light with the shortest wavelength is the thinnest. However, this is not limiting, and the thickness of each EL layer can be adjusted taking into consideration the wavelength of light emitted by each light emitting element, the optical characteristics of the layers constituting the light emitting element, the electrical characteristics of the light emitting element, etc.

[0201] 14C shows a display device 100H that has a microcavity structure achieved by varying the thickness of the EL layer 112 of the display device 100A. FIG. 14C shows a cross section of three light-emitting elements 110 (light-emitting element 110R, light-emitting element 110G, and light-emitting element 110B) arranged side by side in the X direction.

[0202] [Variation 3] A display device 100I shown in FIGS. 15A to 15D differs from the display device 100 described above mainly in that the shape of the insulating layer 131 is different.

[0203] When an inorganic insulating film is used as the insulating layer 131 covering the ends of the pixel electrode 111 and the connection electrode 111C, the insulating layer 131 may have a recess in an area that does not overlap with the pixel electrode 111 and the connection electrode 111C. When an inorganic insulating film is used as the insulating layer 131, impurities are less likely to enter the light-emitting element than when an organic insulating film is used, and the reliability of the light-emitting element can be improved.

[0204] [Variation 4] The display device 100J shown in FIGS. 16A to 16C differs from the display device 100A described above mainly in that it does not have the insulating layer 131.

[0205] By not providing the insulating layer 131, the aperture ratio can be increased in some cases. Alternatively, the distance between light-emitting elements can be narrowed, and the definition or resolution of the display device can be improved in some cases.

[0206] [Variation 5] The display device 100K shown in FIGS. 17A to 17C differs from the display device 100J mainly in that it has an insulating layer 102 and that the pixel electrodes 111 have different configurations.

[0207] The display device 100K has an insulating layer 102 on a substrate 101. The display device 100K also has a configuration in which the pixel electrodes 111 are embedded in openings provided in the insulating layer 102. In other words, the upper surfaces of the pixel electrodes 111 and the insulating layer 102 are generally flush with each other. With this configuration, the EL layer 112 can be formed on a flat surface, thereby improving the coverage of the EL layer 112.

[0208] In this specification, "approximately the same height" refers to a configuration in which the heights from a reference surface (e.g., a flat surface such as a substrate surface) are equal in cross-sectional view. For example, in the manufacturing process of a semiconductor device, a planarization process (typically a CMP process) may be performed to expose the surface of a single layer or multiple layers. In this case, the surfaces processed by the CMP process are configured to be equal in height from the reference surface. "Approximately the same height" also includes cases in which the heights are equal. However, the heights of multiple layers may differ depending on the processing equipment, processing method, or material of the processed surface during the CMP process. In this specification, this case is also considered to be "approximately the same height." For example, when there are two layers (here, a first layer and a second layer) with different heights relative to the reference surface, the difference in height between the top surface of the first layer and the top surface of the second layer is 20 nm or less, this is also considered to be "approximately the same height."

[0209] The above is a description of the modified example.

[0210] 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.

[0211] This embodiment mode can be implemented by appropriately combining at least a part thereof with other embodiment modes described in this specification.

[0212] (Embodiment 2) In this embodiment, a structural example of a display device according to one embodiment of the present invention will be described.

[0213] The display device of the present embodiment can be a high-resolution display device or a large-sized display device. Therefore, the display device of the present embodiment can be used in electronic devices having relatively large screens, such as television devices, desktop or notebook personal computers, computer monitors, digital signage, large game machines such as pachinko machines, as well as display units of digital cameras, digital video cameras, digital photo frames, mobile phones, portable game machines, smartphones, wristwatch-type terminals, tablet terminals, personal digital assistants, and sound reproducing devices.

[0214] [Display device 400A] FIG. 18 shows a perspective view of display device 400A, and FIG. 19A shows a cross-sectional view of display device 400A.

[0215] Display device 400A has a configuration in which substrate 452 and substrate 451 are bonded together. In Fig. 18, substrate 452 is clearly indicated by a dashed line.

[0216] The display device 400A has a display unit 462, a circuit 464, wiring 465, etc. Fig. 18 shows an example in which an IC 473 and an FPC 472 are mounted on the display device 400A. Therefore, the configuration shown in Fig. 18 can also be said to be a display module having the display device 400A, an IC (integrated circuit), and an FPC.

[0217] The circuit 464 can be, for example, a scanning line driver circuit.

[0218] The wiring 465 has a function of supplying signals and power to the display portion 462 and the circuit 464. The signals and power are input to the wiring 465 from the outside via the FPC 472 or input to the wiring 465 from the IC 473.

[0219] 18 shows an example in which an IC 473 is provided on a substrate 451 by a COG (Chip On Glass) method or a COF (Chip on Film) method. The IC 473 may be, for example, an IC having a scanning line driver circuit or a signal line driver circuit. The display device 400A and the display module may not include an IC. Alternatively, the IC may be mounted on an FPC by a COF method or the like.

[0220] FIG. 19A shows an example of a cross section of display device 400A, where a part of the region including FPC 472, a part of circuit 464, a part of display unit 462, and a part of the region including the end portion are cut away.

[0221] The display device 400A shown in Figure 19A has, between a substrate 451 and a substrate 452, a transistor 201, a transistor 205, a light-emitting element 430a that emits red light, a light-emitting element 430b that emits green light, and a light-emitting element 430c that emits blue light.

[0222] The light-emitting element described in Embodiment 1 can be applied to the light-emitting element 430a, the light-emitting element 430b, and the light-emitting element 430c.

[0223] Here, when a pixel of a display device has three types of subpixels having light-emitting elements that emit different colors, the three subpixels include subpixels of three colors R, G, and B, or subpixels of three colors yellow (Y), cyan (C), and magenta (M), etc. When a pixel of a display device has four subpixels, the four subpixels include subpixels of four colors R, G, B, and white (W), or subpixels of four colors R, G, B, and Y, etc.

[0224] The protective layer 416 and the substrate 452 are bonded via an adhesive layer 442. A solid sealing structure, a hollow sealing structure, or the like can be applied to seal the light-emitting element. In FIG. 19A, a space 443 surrounded by the substrate 452, the adhesive layer 442, and the substrate 451 is filled with an inert gas (such as nitrogen or argon), and a hollow sealing structure is applied. The adhesive layer 442 may be provided so as to overlap the light-emitting element. Furthermore, the space 443 surrounded by the substrate 452, the adhesive layer 442, and the substrate 451 may be filled with a resin different from the adhesive layer 442.

[0225] Light-emitting element 430a, light-emitting element 430b, and light-emitting element 430c each have an optical adjustment layer between the pixel electrode and the EL layer. Light-emitting element 430a has optical adjustment layer 426a, light-emitting element 430b has optical adjustment layer 426b, and light-emitting element 430c has optical adjustment layer 426c. For details of the light-emitting elements, refer to Embodiment 1.

[0226] The pixel electrode 411 a, the pixel electrode 411 b, and the pixel electrode 411 c are connected to the conductive layer 222 b of the transistor 205 through openings provided in the insulating layer 214, respectively.

[0227] The pixel electrodes and the edges of the optical adjustment layer are covered with an insulating layer 421. The pixel electrodes include a material that reflects visible light, and the common electrode includes a material that transmits visible light.

[0228] Light emitted from the light-emitting element is emitted toward the substrate 452. The substrate 452 is preferably made of a material that is highly transparent to visible light.

[0229] 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.

[0230] 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 for each transistor. A part of the insulating layer 213 functions as a gate insulating layer for 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.

[0231] 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.

[0232] 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.

[0233] Here, organic insulating films often have lower barrier properties than inorganic insulating films. Therefore, it is preferable that the organic insulating film has an opening near the edge of the display device 400A. This can prevent impurities from entering from the edge of the display device 400A through the organic insulating film. Alternatively, the organic insulating film may be formed so that the edge of the organic insulating film is located inside the edge of the display device 400A, so that the organic insulating film is not exposed at the edge of the display device 400A.

[0234] An organic insulating film is suitable 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.

[0235] 19A, an opening is formed in insulating layer 214. This makes it possible to prevent impurities from entering display section 462 from the outside through insulating layer 214, even when an organic insulating film is used for insulating layer 214. This makes it possible to improve the reliability of display device 400A.

[0236] The transistor 201 and the transistor 205 each include a conductive layer 221 that functions as a gate, an insulating layer 211 that functions as a gate insulating layer, conductive layers 222a and 222b that function as a source and a drain, a semiconductor layer 231, an insulating layer 213 that functions as a gate insulating layer, and a conductive layer 223 that functions as a gate. Here, the same hatching pattern is applied to multiple layers obtained by processing the same conductive film. The insulating layer 211 is located between the conductive layer 221 and the semiconductor layer 231. The insulating layer 213 is located between the conductive layer 223 and the semiconductor layer 231.

[0237] 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.

[0238] 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.

[0239] The crystallinity of the semiconductor material used for the transistor is not particularly limited, and any of an amorphous semiconductor, a single-crystal semiconductor, and a semiconductor having crystallinity other than single crystal (a microcrystalline semiconductor, a polycrystalline semiconductor, or a semiconductor having a crystalline region in part) may be used. The use of a single-crystal semiconductor or a crystalline semiconductor is preferable because it can suppress deterioration of the transistor characteristics.

[0240] 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 using metal oxide in a channel formation region (hereinafter 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 (such as low-temperature polysilicon and single-crystal silicon).

[0241] 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.

[0242] 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.

[0243] 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 compositions in which In:M:Zn=1:1:1 or thereabouts, In:M:Zn=1:1:1.2 or thereabouts, In:M:Zn=2:1:3 or thereabouts, In:M:Zn=3:1:2 or thereabouts, In:M:Zn=4:2:3 or thereabouts, In:M:Zn=4:2:4.1 or thereabouts, In:M:Zn=5:1:3 or thereabouts, In:M:Zn=5:1:6 or thereabouts, In:M:Zn=5:1:7 or thereabouts, In:M:Zn=5:1:8 or thereabouts, In:M:Zn=6:1:6 or thereabouts, and In:M:Zn=5:2:5 or thereabouts, etc. Note that "nearby compositions" includes a range of ±30% of the desired atomic ratio.

[0244] For example, when describing a composition with 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 to 3 and the atomic ratio of Zn is 2 to 4. Furthermore, when describing a composition with 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 greater than 0.1 and less than 2 and the atomic ratio of Zn is greater than 5 and less than 7. Furthermore, when describing a composition with 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 greater than 0.1 and less than 2 and the atomic ratio of Zn is greater than 0.1 and less than 2.

[0245] 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.

[0246] A connection portion 204 is provided in an area of ​​the substrate 451 where the substrate 452 does not overlap. In the connection portion 204, a wiring 465 is electrically connected to the FPC 472 via a conductive layer 466 and a connection layer 242. The conductive layer 466 has an example of a laminated structure of a conductive film obtained by processing the same conductive film as the pixel electrode and a conductive film obtained by processing the same conductive film as the optical adjustment layer. The conductive layer 466 is exposed on the upper 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.

[0247] It is preferable to provide a light-shielding layer 417 on the surface of substrate 452 facing substrate 451. In addition, various optical members can be arranged on the outside of substrate 452. Examples of optical members include a polarizing plate, a retardation plate, a light diffusion layer (such as a diffusion film), an anti-reflection layer, and a light-collecting film. In addition, an antistatic film that suppresses the adhesion of dust, a water-repellent film that makes it difficult for dirt to adhere, a hard coat film that suppresses the occurrence of scratches during use, an impact absorbing layer, etc. may be arranged on the outside of substrate 452.

[0248] By providing the protective layer 416 that covers the light-emitting element, impurities such as water can be prevented from entering the light-emitting element, and the reliability of the light-emitting element can be improved.

[0249] In region 228 near the edge of display device 400A, insulating layer 215 and protective layer 416 preferably contact each other through the opening in insulating layer 214. In particular, it is preferable that the inorganic insulating film of insulating layer 215 and the inorganic insulating film of protective layer 416 contact each other. This makes it possible to prevent impurities from entering display unit 462 from the outside via the organic insulating film. This can therefore improve the reliability of display device 400A.

[0250] 19B shows an example in which the protective layer 416 has a three-layer structure. In FIG. 19B, the protective layer 416 has an inorganic insulating layer 416a on the light-emitting element 430c, an organic insulating layer 416b on the inorganic insulating layer 416a, and an inorganic insulating layer 416c on the organic insulating layer 416b.

[0251] The ends of inorganic insulating layer 416a and inorganic insulating layer 416c extend outward beyond the ends of organic insulating layer 416b and are in contact with each other. Inorganic insulating layer 416a is in contact with insulating layer 215 (inorganic insulating layer) through an opening in insulating layer 214 (organic insulating layer). This allows the insulating layer 215 and protective layer 416 to surround the light-emitting element, thereby improving the reliability of the light-emitting element.

[0252] In this way, the protective layer 416 may have a laminated structure of an organic insulating film and an inorganic insulating film. In this case, it is preferable that the end of the inorganic insulating film extends further outward than the end of the organic insulating film.

[0253] The substrate 451 and the substrate 452 can each be made of glass, quartz, ceramic, sapphire, resin, metal, alloy, semiconductor, or the like. A material that transmits light is used for the substrate on the side from which light from the light-emitting element is extracted. Using a flexible material for the substrate 451 and the substrate 452 can increase the flexibility of the display device. Alternatively, a polarizing plate may be used for the substrate 451 or the substrate 452.

[0254] Substrate 451 and substrate 452 can be made of polyester resin such as polyethylene terephthalate (PET) or polyethylene naphthalate (PEN), polyacrylonitrile resin, acrylic resin, polyimide resin, polymethyl methacrylate resin, polycarbonate (PC) resin, polyethersulfone (PES) resin, polyamide resin (nylon, aramid, etc.), polysiloxane resin, cycloolefin resin, polystyrene resin, polyamideimide resin, polyurethane resin, polyvinyl chloride resin, polyvinylidene chloride resin, polypropylene resin, polytetrafluoroethylene (PTFE) resin, ABS resin, cellulose nanofiber, etc. One or both of substrates 451 and 452 may be made of glass having a thickness sufficient to provide flexibility.

[0255] When a circularly polarizing plate is superimposed on a display device, it is preferable that the display device has a substrate with high optical isotropy. A substrate with high optical isotropy has small birefringence (or a small amount of birefringence).

[0256] 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.

[0257] 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.

[0258] 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.

[0259] The adhesive layer can be made of various curable adhesives, such as photo-curable adhesives (e.g., ultraviolet curable), reactive curable adhesives, thermosetting adhesives, and anaerobic adhesives. Examples of such adhesives include epoxy resin, acrylic resin, silicone resin, phenolic resin, polyimide resin, imide resin, PVC (polyvinyl chloride) resin, PVB (polyvinyl butyral) resin, and EVA (ethylene vinyl acetate) resin. Materials with low moisture permeability, such as epoxy resin, are particularly preferred. Two-component resins may also be used. Adhesive sheets, etc., may also be used.

[0260] The connection layer 242 may be made of an anisotropic conductive film (ACF), an anisotropic conductive paste (ACP), or the like.

[0261] Materials that can be used for the gate (gate terminal or gate electrode), source (source terminal, source region, or source electrode), and drain (drain terminal, drain region, or drain electrode) 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 their main components. Films containing these materials can be used as a single layer or a stacked layer structure.

[0262] 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 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.

[0263] Examples of insulating materials that can be used for each insulating layer include resins such as acrylic resin and epoxy resin, and inorganic insulating materials such as silicon oxide, silicon oxynitride, silicon nitride oxide, silicon nitride, and aluminum oxide.

[0264] [Display device 400B] FIG. 20A shows a cross-sectional view of the display device 400B. The perspective view of the display device 400B is the same as that of the display device 400A (FIG. 18). FIG. 20A shows an example of a cross-section of the display device 400B, when a portion of a region including the FPC 472, a portion of the circuit 464, and a portion of the display unit 462 are cut away. FIG. 20A shows an example of a cross-section of the display unit 462, when a region including the light-emitting element 430b that emits green light and the light-emitting element 430c that emits blue light is cut away. Note that descriptions of parts that are the same as those of the display device 400A may be omitted.

[0265] A display device 400B shown in FIG. 20A includes the transistor 202, the transistor 210, the light-emitting element 430b, the light-emitting element 430c, and the like between a substrate 453 and a substrate 454.

[0266] The substrate 454 and the protective layer 416 are bonded together via an adhesive layer 442. The adhesive layer 442 is provided to overlap the light emitting element 430b and the light emitting element 430c, respectively, and a solid sealing structure is applied to the display device 400B.

[0267] The substrate 453 and the insulating layer 212 are bonded together by an adhesive layer 455 .

[0268] The display device 400B is manufactured by first bonding a fabrication substrate provided with the insulating layer 212, the transistors, the light-emitting elements, and the like to a substrate 454 provided with a light-shielding layer 417 with an adhesive layer 442. Then, the fabrication substrate is peeled off and a substrate 453 is attached to the exposed surface, thereby transferring each component formed on the fabrication substrate to the substrate 453. The substrate 453 and the substrate 454 are preferably flexible. This can increase the flexibility of the display device 400B.

[0269] For the insulating layer 212, the inorganic insulating film that can be used for the insulating layer 211, the insulating layer 213, or the insulating layer 215 can be used.

[0270] The pixel electrode is connected to a conductive layer 222b included in the transistor 210 through an opening provided in the insulating layer 214. The conductive layer 222b is connected to the low-resistance region 231n through openings provided in the insulating layer 215 and the insulating layer 225. The transistor 210 has a function of controlling driving of the light-emitting element.

[0271] The ends of the pixel electrodes are covered with an insulating layer 421 .

[0272] Light emitted from the light-emitting element 430b and the light-emitting element 430c is emitted toward the substrate 454. The substrate 454 is preferably made of a material that is highly transparent to visible light.

[0273] A connection portion 204 is provided in a region of the substrate 453 where the substrate 454 does not overlap. In the connection portion 204, a wiring 465 is electrically connected to the FPC 472 via a conductive layer 466 and a connection layer 242. The conductive layer 466 can be obtained by processing the same conductive film as the pixel electrode. This allows the connection portion 204 and the FPC 472 to be electrically connected via the connection layer 242.

[0274] The transistor 202 and the transistor 210 each include a conductive layer 221 functioning as a gate, an insulating layer 211 functioning as a gate insulating layer, a semiconductor layer 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.

[0275] The conductive layer 222a and the conductive layer 222b are each connected to the low-resistance region 231n through an opening provided in the insulating layer 215. One of the conductive layer 222a and the conductive layer 222b functions as a source, and the other functions as a drain.

[0276] 20A shows an example in which the insulating layer 225 covers the top surface and side surfaces of the semiconductor layer. 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.

[0277] On the other hand, in the transistor 209 shown in FIG. 20B, the insulating layer 225 overlaps with the channel formation region 231i of the semiconductor layer 231 but does not overlap with the low-resistance region 231n. For example, the structure shown in FIG. 20B can be manufactured by processing the insulating layer 225 using the conductive layer 223 as a mask. In FIG. 20B, the insulating layer 215 is provided to cover the insulating layer 225 and the conductive layer 223, and the conductive layer 222a and the conductive layer 222b are each connected to the low-resistance region 231n through openings in the insulating layer 215. Furthermore, an insulating layer 218 may be provided to cover the transistor.

[0278] 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.

[0279] This embodiment mode can be implemented by appropriately combining at least a part thereof with other embodiment modes described in this specification.

[0280] (Embodiment 3) In this embodiment mode, a configuration example of a display device different from the above will be described.

[0281] The display device of the present embodiment can be a high-definition display device, and can therefore be used as a display unit for information terminals (wearable devices) such as wristwatches and bracelets, as well as for wearable devices that can be worn on the head, such as VR devices such as head-mounted displays and AR devices such as glasses.

[0282] [Display module] 21A shows a perspective view of display module 280. Display module 280 has a display device 400C and an FPC 290. Note that the display device included in display module 280 is not limited to display device 400C, and may be display device 400D or display device 400E, which will be described later.

[0283] The display module 280 has a substrate 291 and a substrate 292. The display module 280 has a display unit 281. The display unit 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 unit 284 (described later) can be viewed.

[0284] 21B is a perspective view schematically showing the configuration on the substrate 291 side. A circuit section 282, a pixel circuit section 283 on the circuit section 282, and a pixel section 284 on the pixel circuit section 283 are stacked on the substrate 291. A terminal section 285 for connecting to an FPC 290 is provided in a portion of the substrate 291 that does not overlap with the pixel section 284. The terminal section 285 and the circuit section 282 are electrically connected by a wiring section 286 composed of a plurality of wirings.

[0285] The pixel section 284 has a plurality of periodically arranged pixels 284a. An enlarged view of one pixel 284a is shown on the right side of FIG. 21B. The pixel 284a has light-emitting elements 430a, 430b, and 430c that emit light of different colors. The plurality of light-emitting elements may be arranged in a stripe array as shown in FIG. 21B. The stripe array allows pixel circuits to be arranged at high density, thereby providing a high-resolution display device. Various array methods, such as a delta array and a pentile array, can also be applied.

[0286] The pixel circuit section 283 has a plurality of pixel circuits 283a arranged periodically.

[0287] One pixel circuit 283a is a circuit that controls the light emission of three light-emitting elements included in one pixel 284a. One pixel circuit 283a may be configured to have three circuits that control the light emission of one light-emitting element. For example, the pixel circuit 283a may be configured to have at least one selection transistor, one current control transistor (drive transistor), and a capacitance element for each light-emitting element. In this case, a gate signal is input to the gate of the selection transistor, and a source signal is input to either the source or the drain. This realizes an active matrix display device.

[0288] The circuit portion 282 includes a circuit for driving each pixel circuit 283a of the pixel circuit portion 283. For example, it is preferable that the circuit portion 282 includes one or both of a gate line driver circuit and a source 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.

[0289] The FPC 290 functions as wiring for supplying a video signal, a power supply potential, or the like from the outside to the circuit section 282. An IC may also be mounted on the FPC 290.

[0290] 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 284a 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 284a 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.

[0291] Such a display module 280 has extremely high resolution and can therefore be suitably used in VR devices such as head-mounted displays or eyeglass-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 that even if the display unit is enlarged with the 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 having relatively small display units. For example, it can be suitably used in the display unit of a wearable electronic device such as a wristwatch.

[0292] [Display device 400C] The display device 400C shown in FIG. 22 includes a substrate 301, a light emitting element 430a, a light emitting element 430b, a light emitting element 430c, a capacitor 240, and a transistor 310.

[0293] 21A and 21B. Layer structure 401 from substrate 301 to insulating layer 255 corresponds to substrate 101 in the first embodiment.

[0294] 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 either a source or a drain. The insulating layer 314 is provided to cover a side surface of the conductive layer 311 and functions as an insulating layer.

[0295] Furthermore, an element isolation layer 315 is provided between two adjacent transistors 310 so as to be embedded in the substrate 301 .

[0296] In addition, an insulating layer 261 is provided to cover the transistor 310 , and a capacitor 240 is provided on the insulating layer 261 .

[0297] Capacitor 240 has conductive layer 241, conductive layer 245, and insulating layer 243 positioned therebetween. Conductive layer 241 functions as one electrode of capacitor 240, conductive layer 245 functions as the other electrode of capacitor 240, and insulating layer 243 functions as a dielectric of capacitor 240.

[0298] 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 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.

[0299] An insulating layer 255 is provided to cover the capacitor 240, and light emitting elements 430a, 430b, 430c, etc. are provided on the insulating layer 255. A protective layer 416 is provided on the light emitting elements 430a, 430b, and 430c, and a substrate 420 is bonded to the upper surface of the protective layer 416 by a resin layer 419. The substrate 420 corresponds to the substrate 292 in FIG. 21A.

[0300] The pixel electrode of the light-emitting element is electrically connected to one of the source or drain of the transistor 310 by a plug 256 embedded in the insulating layer 255, a conductive layer 241 embedded in the insulating layer 254, and a plug 271 embedded in the insulating layer 261.

[0301] [Display device 400D] 23 differs from display device 400C mainly in the configuration of the transistors, and a description of the same parts as display device 400C may be omitted.

[0302] The transistor 320 is a transistor in which a metal oxide (also referred to as an oxide semiconductor) is used for a semiconductor layer in which a channel is formed.

[0303] 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 .

[0304] 21A and 21B. Layer structure 401 from substrate 331 to insulating layer 255 corresponds to substrate 101 in Embodiment 1. Substrate 331 can be an insulating substrate or a semiconductor substrate.

[0305] 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.

[0306] 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.

[0307] The semiconductor layer 321 is provided over the insulating layer 326. The semiconductor layer 321 preferably includes a metal oxide (also referred to as an oxide semiconductor) film having semiconductor properties. Materials that can be suitably used for the semiconductor layer 321 will be described in detail later.

[0308] A pair of conductive layers 325 is provided over and in contact with the semiconductor layer 321 and functions as a source electrode and a drain electrode.

[0309] 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.

[0310] An opening reaching the semiconductor layer 321 is provided in the insulating layer 328 and the insulating layer 264. An insulating layer 323 and a conductive layer 324 are buried inside the opening and are in contact with the side surfaces of the insulating layer 264, the insulating layer 328, and the conductive layer 325 and the top 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.

[0311] 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.

[0312] 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.

[0313] A 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, and the insulating layer 264. Here, the plug 274 preferably includes a conductive layer 274a covering the side surfaces of the openings in 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.

[0314] The configuration from the insulating layer 254 to the substrate 420 in the display device 400D is the same as that in the display device 400C.

[0315] [Display device 400E] 24 has a stacked structure of a transistor 310 having a channel formed in a substrate 301 and a transistor 320 having a channel formed in a semiconductor layer containing a metal oxide. Note that descriptions of parts similar to those of the display device 400C and the display device 400D may be omitted.

[0316] 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 a 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.

[0317] 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 (gate line driver circuit, source 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.

[0318] With this configuration, not only pixel circuits but also driver circuits and the like can be formed directly under the light-emitting elements, making it possible to miniaturize the display device compared to when driver circuits are provided around the periphery of the display area.

[0319] 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.

[0320] This embodiment mode can be implemented by appropriately combining at least a part thereof with other embodiment modes described in this specification.

[0321] (Fourth embodiment) In this embodiment, a light-emitting element (also referred to as a light-emitting device) that can be used for a display device that is one embodiment of the present invention will be described.

[0322] <Configuration example of light-emitting element> As shown in FIG. 25A, the light-emitting element has an EL layer 23 between a pair of electrodes (a lower electrode 21 and an upper electrode 25). The EL layer 23 can be composed of multiple 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).

[0323] A structure having the layer 4420, the light-emitting layer 4411, and the layer 4430 provided between a pair of electrodes can function as one light-emitting unit, and the structure of FIG. 25A is referred to as a single structure in this specification.

[0324] 25B shows a modified example of the EL layer 23 included in the light-emitting element 20 shown in Fig. 25A. Specifically, the light-emitting element 20 shown in Fig. 25B includes a layer 4430-1 on the lower electrode 21, a layer 4430-2 on the layer 4430-1, a light-emitting layer 4411 on the layer 4430-2, a layer 4420-1 on the light-emitting layer 4411, a layer 4420-2 on the layer 4420-1, and an upper electrode 25 on the layer 4420-2. For example, when the lower electrode 21 is an anode and the upper electrode 25 is a cathode, the layer 4430-1 functions as a hole injection layer, the layer 4430-2 functions as a hole transport layer, the layer 4420-1 functions as an electron transport layer, and the layer 4420-2 functions as an electron injection layer. Alternatively, when the lower electrode 21 is used as a cathode and the upper electrode 25 is used as an anode, the layer 4430-1 functions as an electron injection layer, the layer 4430-2 functions as an electron transport layer, the layer 4420-1 functions as a hole transport layer, and the layer 4420-2 functions as a hole injection layer. By using such a layer structure, it is possible to efficiently inject carriers into the light-emitting layer 4411 and increase the efficiency of carrier recombination in the light-emitting layer 4411.

[0325] As shown in FIG. 25C, a configuration in which a plurality of light-emitting layers (light-emitting layer 4411, light-emitting layer 4412, light-emitting layer 4413) are provided between layer 4420 and layer 4430 is also a variation of the single structure.

[0326] Furthermore, as shown in FIG. 25D, a configuration in which a plurality of light-emitting units (EL layer 23a, EL layer 23b) are connected in series via an intermediate layer 4440 is referred to as a tandem structure in this specification. Note that the intermediate layer 4440 may also be referred to as a charge generation layer. Furthermore, in this specification and the like, the configuration as shown in FIG. 25D is referred to as a tandem structure, but 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.

[0327] 25C and 25D, the layer 4420 and the layer 4430 may have a laminated structure made up of two or more layers, as shown in FIG. 25B.

[0328] The light-emitting element can emit light in red, green, blue, cyan, magenta, yellow, or white, depending on the material of the EL layer 23. Furthermore, the color purity can be further improved by providing the light-emitting element with a microcavity structure.

[0329] The light-emitting layer preferably contains two or more light-emitting materials that emit light of R (red), G (green), B (blue), Y (yellow), O (orange), etc. Alternatively, it is preferable that the light-emitting layer contains two or more light-emitting materials, and the light emitted by each of the light-emitting materials contains spectral components of two or more colors of R, G, and B.

[0330] Here, a specific example of the configuration of the light-emitting element will be described.

[0331] The light-emitting element has at least a light-emitting layer. The light-emitting element may further have 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, an electron-blocking material, a substance with high electron-injection properties, a bipolar substance (a substance with high electron-transport properties and high hole-transport properties), or the like, in addition to the light-emitting layer.

[0332] The light-emitting device can be made of either a low-molecular-weight compound or a high-molecular-weight compound, and may contain an inorganic compound. The layers constituting the light-emitting device can be formed by a method such as vapor deposition (including vacuum vapor deposition), transfer, printing, inkjet printing, or coating.

[0333] For example, a light emitting device can include 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.

[0334] 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).

[0335] 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 material having a hole mobility of 1 / Vs or more is preferred. Note that other materials can also be used as long as they have a higher hole transporting property than electron transporting property. As the hole transporting material, a material having a high hole transporting property, such as a π-electron-rich heteroaromatic compound (e.g., a carbazole derivative, a thiophene derivative, a furan derivative, etc.) or an aromatic amine (a compound having an aromatic amine skeleton), is preferred.

[0336] The electron transport layer is a layer that transports electrons injected from the cathode by the electron injection layer to the light emitting layer. The electron transport layer is a layer that contains an electron transporting material. The electron transporting material is a material having a molecular weight of 1×10 -6 cm 2 A substance having an electron mobility of 1 / Vs or more is preferred. Note that other substances can also be used as long as they have a higher electron transporting property than holes. Examples of electron-transporting materials that can be used include metal complexes having a quinoline skeleton, metal complexes having a benzoquinoline skeleton, metal complexes having an oxazole skeleton, and metal complexes having a thiazole skeleton, as well as oxadiazole derivatives, triazole derivatives, imidazole derivatives, oxazole derivatives, thiazole derivatives, phenanthroline derivatives, quinoline derivatives having a quinoline ligand, benzoquinoline derivatives, quinoxaline derivatives, dibenzoquinoxaline derivatives, pyridine derivatives, bipyridine derivatives, pyrimidine derivatives, and π-electron-deficient heteroaromatic compounds including nitrogen-containing heteroaromatic compounds.

[0337] 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).

[0338] Examples of the electron injection layer include lithium, cesium, lithium fluoride (LiF), cesium fluoride (CsF), calcium fluoride (CaF), 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), and lithium oxide (LiO x ), alkali metals such as cesium carbonate, alkaline earth metals, or compounds thereof can be used.

[0339] Alternatively, the electron injection layer may be formed using a material having electron transport properties. For example, a compound having an unshared electron pair and an electron-deficient heteroaromatic ring may be used as the material having electron transport properties. Specifically, a compound having at least one of a pyridine ring, a diazine ring (pyrimidine ring, pyrazine ring, pyridazine ring), and a triazine ring may be used.

[0340] 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.

[0341] Examples of organic compounds with lone electron pairs include 4,7-diphenyl-1,10-phenanthroline (abbreviated as BPhen), 2,9-bis(naphthalen-2-yl)-4,7-diphenyl-1,10-phenanthroline (abbreviated as NBPhen), diquinoxalino[2,3-a:2',3'-c]phenazine (abbreviated as HATNA), and 2,4,6-tris[3'-(pyridin-3-yl)biphenyl-3-yl]-1,3,5-triazine (abbreviated as TmPPPyTz). NBPhen has a higher glass transition temperature (Tg) and better heat resistance than BPhen.

[0342] The light-emitting layer is a layer containing a light-emitting substance. The light-emitting layer can contain one or more light-emitting substances. As the light-emitting substance, a substance that emits light of a color such as blue, purple, blue-purple, green, yellow-green, yellow, orange, or red is appropriately used. Furthermore, a substance that emits near-infrared light can also be used as the light-emitting substance.

[0343] Examples of light-emitting materials include fluorescent materials, phosphorescent materials, TADF materials, and quantum dot materials.

[0344] 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.

[0345] 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.

[0346] 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). One or more organic compounds may be a hole-transporting material or an electron-transporting material, or both. Alternatively, a bipolar material or a TADF material may be used as the one or more organic compounds.

[0347] The light-emitting layer preferably contains, 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-Triplet 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, allowing for efficient emission. This configuration simultaneously enables high efficiency, low-voltage operation, and long life of the light-emitting device.

[0348] Conductive films that transmit visible light and can be used for the cathode and anode can be formed using, for example, indium oxide, indium tin oxide, indium tin oxide containing silicon oxide (ITSO), indium zinc oxide, zinc oxide, zinc oxide, or zinc oxide doped with gallium. Metallic materials such as gold, silver, platinum, magnesium, nickel, tungsten, chromium, molybdenum, iron, cobalt, copper, palladium, or titanium, alloys containing these metallic materials, or nitrides of these metallic materials (e.g., titanium nitride), can also be used by forming them thin enough to transmit light. 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 with indium tin oxide or indium tin oxide containing silicon is preferable because it can increase conductivity. Graphene, etc., can also be used.

[0349] The cathode or anode preferably uses a conductive film that reflects visible light. Examples of the conductive film include metal materials such as aluminum, gold, platinum, silver, nickel, tungsten, chromium, molybdenum, iron, cobalt, copper, and palladium, or alloys containing these metal materials. Silver is preferred because it has a high reflectance for visible light. Aluminum is also preferred because it is easy to process and has a high reflectance for visible light and near-infrared light. Lanthanum, neodymium, germanium, or the like may be added to the above metal materials or alloys. Furthermore, alloys containing titanium, nickel, or neodymium and aluminum (aluminum alloys) may also be used. Furthermore, alloys containing copper, palladium, magnesium, and silver may also be used. Alloys containing silver and copper are preferred because they have high heat resistance.

[0350] The cathode or anode may also have a structure in which a conductive metal film or metal oxide film is stacked on the conductive film that reflects visible light. This structure can suppress oxidation or corrosion of the conductive film that reflects visible light. For example, stacking a metal film or metal oxide film in contact with an aluminum film or an aluminum alloy film can suppress oxidation. Examples of materials for such metal films or metal oxide films include titanium and titanium oxide. Alternatively, the conductive film that transmits visible light may be stacked with a film made of a metal material. For example, a stacked film of silver and indium tin oxide, or a stacked film of a silver-magnesium alloy and indium tin oxide may be used. The metal film or metal oxide film may also be provided under the conductive film that reflects visible light.

[0351] When aluminum is used as the cathode or anode, the thickness is preferably 40 nm or more, more preferably 70 nm or more, to sufficiently increase the reflectance of visible light, etc. When silver is used as the cathode or anode, the thickness is preferably 70 nm or more, more preferably 100 nm or more, to sufficiently increase the reflectance of visible light, etc.

[0352] As a conductive film having light-transmitting and reflective properties that can be used for a cathode or an anode, a film obtained by forming the above-mentioned conductive film that reflects visible light to a thickness that is thin enough to transmit visible light can be used. In addition, by forming a laminate structure of the conductive film and the above-mentioned conductive film that transmits visible light, conductivity or mechanical strength can be increased.

[0353] The reflectance of a light-transmitting and reflective conductive film to visible light (for example, the reflectance to light of a predetermined wavelength in the range of 400 nm to 700 nm) is preferably 20% to 80% and more preferably 40% to 70%. The reflectance of a reflective conductive film to visible light is preferably 40% to 100% and more preferably 70% to 100%. The reflectance of a light-transmitting conductive film to visible light is preferably 0% to 40% and more preferably 0% to 30%.

[0354] The electrodes constituting the light-emitting element may be formed by vapor deposition, sputtering, or the like. Alternatively, they may be formed by a discharge method such as an ink-jet method, a printing method such as a screen printing method, or a plating method.

[0355] 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.

[0356] This embodiment mode can be implemented by appropriately combining at least a part thereof with other embodiment modes described in this specification.

[0357] (Embodiment 5) In this embodiment, a metal oxide (also referred to as an oxide semiconductor) that can be used for the OS transistor described in the above embodiment will be described.

[0358] The metal oxide preferably contains at least indium or zinc. It is particularly preferable that it contains indium and zinc. It is also 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.

[0359] Furthermore, the metal oxide can be formed by a sputtering method, a chemical vapor deposition (CVD) method such as a metal organic chemical vapor deposition (MOCVD) method, or an atomic layer deposition (ALD) method.

[0360] <Classification of crystal structures> Examples of the crystalline structure of oxide semiconductors include amorphous (including completely amorphous), c-axis-aligned crystalline (CAAC), nanocrystalline (nc), cloud-aligned composite (CAC), single crystal, and polycrystal.

[0361] The crystalline structure of a film or substrate can be evaluated using X-ray diffraction (XRD) spectra. For example, it can be evaluated using XRD spectra obtained by GIXD (Grazing-Incidence XRD) measurements. The GIXD method is also called the thin film method or the Seemann-Bohlin method.

[0362] For example, for a quartz glass substrate, the peak shape of the XRD spectrum is nearly symmetrical. On the other hand, for an IGZO film with a crystalline structure, the peak shape of the XRD spectrum is asymmetrical. The asymmetrical peak shape of the XRD spectrum clearly indicates the presence of crystals in the film or substrate. In other words, if the peak shape of the XRD spectrum is not symmetrical, the film or substrate cannot be said to be in an amorphous state.

[0363] The crystalline structure of a film or substrate can also be evaluated by the diffraction pattern (also called the nanobeam electron diffraction pattern) observed using nanobeam electron diffraction (NBED). For example, a halo is observed in the diffraction pattern of a quartz glass substrate, confirming that the quartz glass is in an amorphous state. Furthermore, a spot-like pattern is observed in the diffraction pattern of an IGZO film deposited at room temperature, rather than a halo. For this reason, it is estimated that an IGZO film deposited at room temperature is neither crystalline nor amorphous, but is in an intermediate state, and it cannot be concluded that it is in an amorphous state.

[0364] <<Oxide semiconductor structure>> Note that oxide semiconductors may be classified differently from the above when focusing on their structures. For example, oxide semiconductors are divided 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, amorphous-like oxide semiconductors (a-like OSs), amorphous oxide semiconductors, and the like.

[0365] Here, the above-mentioned CAAC-OS, nc-OS, and a-like OS will be described in detail.

[0366] [CAAC-OS] CAAC-OS is an oxide semiconductor having multiple crystalline regions, each with its c-axis aligned in a specific direction. The specific direction can be the thickness direction of the CAAC-OS film, the normal direction to the surface on which the CAAC-OS film is formed, or the normal direction to the surface of the CAAC-OS film. A crystalline region is a region with periodic atomic arrangement. If the atomic arrangement is considered as a lattice arrangement, a crystalline region can also be a region with a uniform lattice arrangement. Furthermore, CAAC-OS has a region where multiple crystalline regions are connected in the ab-plane direction, and the region may have distortion. Note that distortion refers to a location where the lattice arrangement changes between a region with a uniform lattice arrangement and a region with a different uniform lattice arrangement in the region where multiple crystalline regions are connected. In other words, CAAC-OS is an oxide semiconductor with a c-axis aligned but no clear orientation in the ab-plane direction.

[0367] 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 maximum diameter of the crystalline region may be several tens of nm.

[0368] In an In-M-Zn oxide (wherein M is one or more elements selected from aluminum, gallium, yttrium, tin, titanium, etc.), 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 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 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.

[0369] When the CAAC-OS film is subjected to structural analysis using, for example, an XRD apparatus, a peak indicating c-axis orientation is detected at or near 2θ=31° in out-of-plane XRD measurement using θ / 2θ scan. Note that the position of the peak indicating c-axis orientation (2θ value) may vary depending on the type and composition of the metallic elements constituting the CAAC-OS.

[0370] For example, in the electron diffraction pattern of a CAAC-OS film, multiple bright spots are observed, and the spots are observed at positions that are point-symmetric with respect to the spot of the incident electron beam that has passed through the sample (also called the direct spot).

[0371] When the crystalline region is observed from the specific direction, the lattice arrangement within the crystalline region is basically a hexagonal lattice, but the unit cell is not necessarily a regular hexagon and may be non-regular hexagonal. Furthermore, the distortion may have a pentagonal, heptagonal, or other lattice arrangement. In the CAAC-OS, no clear grain boundaries are observed even near the distortion. This indicates that the formation of grain boundaries is suppressed by the distortion of the lattice arrangement. This is thought to be because the CAAC-OS can tolerate distortion due to the lack of close-packed arrangement of oxygen atoms in the ab-plane direction or the change in interatomic bond distance caused by metal atom substitution.

[0372] A crystal structure with clear grain boundaries is called polycrystalline. Grain boundaries act as recombination centers, trapping carriers and potentially causing a decrease in the on-state current and field-effect mobility of a transistor. Therefore, CAAC-OS, which lacks clear grain boundaries, is one of the crystalline oxides with a crystal structure suitable for use in the semiconductor layer of a transistor. Zn is preferred for use in 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.

[0373] 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 impurities or defects, the CAAC-OS can be said to be an oxide semiconductor with few impurities and defects (such as oxygen vacancies). Therefore, oxide semiconductors with CAAC-OS have stable physical properties. Therefore, oxide semiconductors with CAAC-OS are heat-resistant and highly reliable. Furthermore, the CAAC-OS is stable even under high temperatures (so-called thermal budgets) during the manufacturing process. Therefore, using a CAAC-OS for an OS transistor can increase the flexibility of the manufacturing process.

[0374] [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 microcrystalline structures. The size of the microcrystalline structures is, for example, 1 nm to 10 nm, particularly 1 nm to 3 nm, and therefore these microcrystalline structures are also called nanocrystalline structures. Furthermore, the nc-OS exhibits no regularity in the crystal orientation between different nanocrystalline structures. Therefore, the entire film lacks orientation. Therefore, depending on the analytical 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 system, no peaks indicating crystallinity are detected in out-of-plane XRD measurements using θ / 2θ scanning. Furthermore, when an nc-OS film is subjected to electron diffraction (also known as selected-area electron diffraction) using an electron beam with a probe diameter larger than that of nanocrystalline structures (e.g., 50 nm or larger), a halo-like diffraction pattern is observed. On the other hand, when electron diffraction (also called nanobeam electron diffraction) is performed on an nc-OS film using an electron beam with a probe diameter close to or smaller than the size of the nanocrystals (for example, 1 nm to 30 nm), an electron diffraction pattern can be obtained in which multiple spots are observed within a ring-shaped region centered on the direct spot.

[0375] [a-like OS] The a-like OS is an oxide semiconductor having a structure between the nc-OS and the amorphous oxide semiconductor. The a-like OS has a pore or low-density region. That is, the a-like OS has lower crystallinity than the nc-OS and CAAC-OS. Furthermore, the a-like OS has a higher hydrogen concentration in the film than the nc-OS and CAAC-OS.

[0376] <<Oxide semiconductor structure>> Next, the above-mentioned CAC-OS will be described in detail, which relates to the material composition.

[0377] [CAC-OS] CAC-OS is a material structure in which elements constituting a metal oxide are unevenly distributed in a size range of 0.5 nm to 10 nm, preferably 1 nm to 3 nm, or a similar size range. Hereinafter, a metal oxide in which one or more metal elements are unevenly distributed and the regions containing the metal elements are mixed in a size range of 0.5 nm to 10 nm, preferably 1 nm to 3 nm, or a similar size range, is also referred to as a mosaic or patch state.

[0378] Furthermore, CAC-OS has a mosaic structure in which the material is separated into first and second regions, and the first regions are distributed throughout the film (hereinafter also referred to as a cloud structure). That is, CAC-OS is a composite metal oxide having a structure in which the first and second regions are mixed.

[0379] 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.

[0380] 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.

[0381] It should be noted that there are cases where a clear boundary between the first region and the second region cannot be observed.

[0382] In addition, CAC-OS in In-Ga-Zn oxide refers to a material structure containing In, Ga, Zn, and O, in which some regions primarily composed of Ga and other regions primarily composed of In are randomly arranged in a mosaic pattern. Therefore, it is presumed that CAC-OS has a structure in which metal elements are distributed nonuniformly.

[0383] The CAC-OS can be formed, for example, by a sputtering method under conditions where the substrate is not intentionally heated. When the CAC-OS is formed by a sputtering method, any one or more of an inert gas (typically argon), oxygen gas, and nitrogen gas may be used as the deposition gas. The lower the flow rate ratio of oxygen gas to the total flow rate of deposition gas during deposition, the better. For example, the flow rate ratio of oxygen gas 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.

[0384] Furthermore, for example, in the case of CAC-OS in an In-Ga-Zn oxide, EDX mapping obtained using EDX (Energy Dispersive X-ray spectroscopy) confirms 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.

[0385] 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).

[0386] On the other hand, the second region has higher insulating properties than the first region. That is, the second region is distributed in the metal oxide, thereby suppressing leakage current.

[0387] Therefore, when 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 (the ability to turn on / off). In other words, CAC-OS has a conductive function in part of the material and an insulating function in part of the material, and the material as a whole functions as a semiconductor. By separating the conductive function from the insulating function, both functions can be maximized. Therefore, by using CAC-OS in a transistor, a high on-current (I on ), high field-effect mobility (μ), and good switching behavior can be achieved.

[0388] Furthermore, a transistor using CAC-OS has high reliability, making it ideal for various semiconductor devices such as display devices.

[0389] Oxide semiconductors have a variety of structures, each with 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.

[0390] <Transistors containing oxide semiconductors> Next, a case where the oxide semiconductor is used in a transistor will be described.

[0391] By using the oxide semiconductor for a transistor, a transistor with high field-effect mobility and high reliability can be realized.

[0392] 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 Less than 1 × 10 15 cm -3 or less, more preferably 1 × 10 13 cm -3Less than 1×10, more preferably 11 cm -3 or less, more preferably 1 × 10 10 cm -3 Less than 1 x 10 -9 cm -3 That is all. Note that in order to reduce the carrier concentration of an oxide semiconductor film, the impurity concentration in the oxide semiconductor film may be reduced to reduce the density of defect states. In this specification and the like, a semiconductor having a low impurity concentration and a low density of defect states is referred to as a highly purified intrinsic or substantially highly purified intrinsic oxide semiconductor. Note that an oxide semiconductor having a low carrier concentration may also be referred to as a highly purified intrinsic or substantially highly purified intrinsic oxide semiconductor.

[0393] 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.

[0394] Furthermore, charges trapped in the trap states of an oxide semiconductor take a long time to disappear 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.

[0395] 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 the adjacent film. Examples of impurities include hydrogen, nitrogen, alkali metals, alkaline earth metals, iron, nickel, and silicon.

[0396] <Impurities> Here, the influence of each impurity in an oxide semiconductor will be described.

[0397] When an oxide semiconductor contains silicon or carbon, which is one of the 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 Less than or equal to 2 x 10 17 atoms / cm 3 The following applies.

[0398] Furthermore, when an oxide semiconductor contains an alkali metal or alkaline earth metal, defect levels may be formed and carriers may be generated. Therefore, a transistor using an oxide semiconductor containing an alkali metal or alkaline earth metal is likely to have normally-on characteristics. Therefore, when the concentration of the alkali metal or alkaline earth metal in the oxide semiconductor obtained by SIMS is 1×10 18 atoms / cm 3 Less than or equal to 2 x 10 16 atoms / cm 3 Do the following:

[0399] Furthermore, when nitrogen is contained in an oxide semiconductor, electrons serving as carriers are generated, the carrier concentration increases, and the semiconductor is likely to become n-type. As a result, a transistor using an oxide semiconductor containing nitrogen as a semiconductor tends to have normally-on characteristics. Alternatively, when nitrogen is contained in an oxide semiconductor, trap states may be formed. As a result, the electrical characteristics of the transistor may become unstable. For this reason, the nitrogen concentration in the oxide semiconductor obtained by SIMS is set to 5×10 19 atoms / cm 3 Less than 5 x 10 18 atoms / cm 3 Less than 1×10, more preferably 18 atoms / cm 3 Less than 5 × 10, more preferably 17 atoms / cm 3 Do the following:

[0400] 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. When hydrogen enters the oxygen vacancy, electrons serving as carriers may be generated. Furthermore, some of the hydrogen may bond with oxygen bonded to a metal atom to generate electrons serving as carriers. Therefore, a transistor using an oxide semiconductor containing hydrogen is likely to have normally-on characteristics. For this reason, it is preferable to reduce the amount of hydrogen in the oxide semiconductor as much as possible. Specifically, the hydrogen concentration in an oxide semiconductor measured by SIMS is 1×10 20 atoms / cm 3 Less than 1 x 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.

[0401] When an oxide semiconductor with sufficiently reduced impurities is used for a channel formation region of a transistor, stable electrical characteristics can be obtained.

[0402] This embodiment mode can be implemented by appropriately combining at least a part thereof with other embodiment modes described in this specification.

[0403] (Sixth embodiment) In this embodiment, electronic devices of one embodiment of the present invention will be described with reference to FIGS.

[0404] 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.

[0405] 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.

[0406] 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.

[0407] In particular, the display device of one embodiment of the present invention can achieve high resolution and is therefore suitable for use in electronic devices having a relatively small display area. Examples of such electronic devices include information terminals (wearable devices) such as wristwatches and bracelets, as well as head-mounted wearable devices such as VR devices and glasses-type AR devices. Further examples of wearable devices include SR devices and MR devices.

[0408] The display device of one embodiment of the present invention preferably has an extremely high resolution such as HD (1280 × 720 pixels), FHD (1920 × 1080 pixels), WQHD (2560 × 1440 pixels), WQXGA (2560 × 1600 pixels), 4K2K (3840 × 2160 pixels), or 8K4K (7680 × 4320 pixels). A resolution of 4K2K, 8K4K, or higher is particularly preferable. Furthermore, the pixel density (resolution) of the display device of one embodiment of the present invention is preferably 300 ppi or higher, more preferably 500 ppi or higher, more preferably 1000 ppi or higher, more preferably 2000 ppi or higher, more preferably 3000 ppi or higher, more preferably 5000 ppi or higher, and even more preferably 7000 ppi or higher. By using a display device with such high resolution or high definition, it is possible to further enhance the sense of presence and depth in electronic devices for personal use such as portable or home use.

[0409] 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.

[0410] 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.

[0411] The electronic device of this embodiment may have a sensor (including the function of sensing, detecting, or measuring force, displacement, position, velocity, acceleration, angular velocity, rotation speed, distance, light, liquid, magnetism, temperature, chemical substance, sound, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, gradient, vibration, odor, or infrared light).

[0412] The electronic device of the present embodiment can have various functions, such as a function to display various information (still images, videos, text images, etc.) on a display unit, a touch panel function, a function to display a calendar, date, time, etc., a function to execute various software (programs), a wireless communication function, a function to read out programs or data recorded on a recording medium, etc.

[0413] Electronic device 6500 shown in FIG. 26A is a portable information terminal that can be used as a smartphone.

[0414] 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, and a light source 6508. The display portion 6502 has a touch panel function.

[0415] The display device of one embodiment of the present invention can be applied to the display portion 6502.

[0416] FIG. 26B is a schematic cross-sectional view including the end of the housing 6501 on the microphone 6506 side.

[0417] A light-transmitting protective member 6510 is provided on the display surface side of the housing 6501, and a display panel 6511, optical members 6512, a touch sensor panel 6513, a printed circuit board 6517, a battery 6518, etc. are arranged in the space surrounded by the housing 6501 and the protective member 6510.

[0418] 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).

[0419] In an area outside the display unit 6502, a part of the display panel 6511 is folded back, and an FPC 6515 is connected to the folded back part. An IC 6516 is mounted on the FPC 6515. The FPC 6515 is connected to a terminal provided on a printed circuit board 6517.

[0420] 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.

[0421] 27A shows an example of a television device. A television device 7100 has a display unit 7000 built into a housing 7101. Here, the housing 7101 is supported by a stand 7103.

[0422] The display device of one embodiment of the present invention can be applied to the display portion 7000.

[0423] 27A can be operated using operation switches provided on the housing 7101 and a separate remote control 7111. Alternatively, a touch sensor may be provided in the display unit 7000, and the television 7100 may be operated by touching the display unit 7000 with a finger or the like. The remote control 7111 may have a display unit that displays information output from the remote control 7111. The channel and volume can be controlled using operation keys or a touch panel provided on the remote control 7111, and the video displayed on the display unit 7000 can be controlled.

[0424] The television device 7100 is configured to include a receiver, a modem, and the like. The receiver can receive general television broadcasts. In addition, by connecting to a wired or wireless communication network via the modem, it is possible to perform one-way (from sender to receiver) or two-way (between sender and receiver, or between receivers, etc.) information communication.

[0425] 27B 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.

[0426] The display device of one embodiment of the present invention can be applied to the display portion 7000.

[0427] 27C and 27D show an example of digital signage.

[0428] 27C includes a housing 7301, a display unit 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.

[0429] 27D 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.

[0430] 27C and 27D, the display device of one embodiment of the present invention can be applied to the display portion 7000.

[0431] 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.

[0432] 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, intuitive operation can improve usability.

[0433] 27C and 27D, it is preferable that the digital signage 7300 or the digital signage 7400 can be linked via wireless communication 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. Furthermore, the display on the display unit 7000 can be switched by operating the information terminal 7311 or the information terminal 7411.

[0434] Furthermore, it is also possible to cause the digital signage 7300 or the digital signage 7400 to execute 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.

[0435] FIG. 28A is a diagram showing the appearance of the camera 8000 with the viewfinder 8100 attached.

[0436] The camera 8000 includes a housing 8001, a display unit 8002, operation buttons 8003, a shutter button 8004, etc. 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.

[0437] The camera 8000 can capture an image by pressing a shutter button 8004 or touching a display unit 8002 that functions as a touch panel.

[0438] The housing 8001 has a mount with electrodes, and can be connected to a finder 8100 as well as a strobe device and the like.

[0439] The finder 8100 includes a housing 8101, a display portion 8102, a button 8103, and the like.

[0440] 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 unit 8102.

[0441] The button 8103 has a function such as a power button.

[0442] 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.

[0443] FIG. 28B is a diagram showing the appearance of the head mounted display 8200.

[0444] 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.

[0445] A cable 8205 supplies power from a battery 8206 to the main body 8203. The main body 8203 includes a wireless receiver or the like, and can display received video information on a display portion 8204. The main body 8203 also includes a camera, and can use information on the movement of the user's eyeballs or eyelids as an input means.

[0446] The wearing unit 8201 may have a function of recognizing the line of sight by providing 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. The wearing unit 8201 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 have various sensors, such as a temperature sensor, a pressure sensor, and an acceleration sensor, and may also have a function of displaying the user's biological information on the display unit 8204 and a function of changing the image displayed on the display unit 8204 in accordance with the movement of the user's head.

[0447] The display device of one embodiment of the present invention can be applied to the display portion 8204.

[0448] 28C to 28E 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.

[0449] A user can view the display on the display portion 8302 through the lens 8305. Note that it is preferable to arrange the display portion 8302 in a curved manner 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 3D 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.

[0450] 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 resolution. For example, even when the display is enlarged and viewed using the lens 8305 as shown in FIG. 28E, the pixels are hardly visible to the user. That is, the display portion 8302 allows the user to view a highly realistic image.

[0451] 28F 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, a mounting portion 8402, and a cushioning 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, a 3D display using parallax can be performed.

[0452] A user can view the display portion 8404 through the lens 8405. The lens 8405 has a focus adjustment mechanism that can adjust the position of the lens 8405 according to the user's eyesight. The display portion 8404 is preferably a square or a horizontally long rectangle. This can enhance the sense of realism.

[0453] The wearing part 8402 is preferably adjustable to fit the size of the user's face and has plasticity and elasticity to prevent it from slipping off. Furthermore, a part of the wearing part 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 earphone, without the need for separate audio equipment such as earphones or speakers. The housing 8401 may also have a function to output audio data via wireless communication.

[0454] The mounting unit 8402 and the buffer member 8403 are portions that come into contact with the user's face (forehead, cheeks, etc.). The close contact of the buffer member 8403 with the user's face can prevent light leakage and enhance the sense of immersion. The buffer member 8403 is preferably made of a soft material so that it can be in close contact with the user's face when the user wears the head-mounted display 8400. For example, materials such as rubber, silicone rubber, urethane, and sponge can be used. Furthermore, using a sponge or the like with its surface covered with cloth or leather (natural leather or synthetic leather) can prevent gaps from forming between the user's face and the buffer member 8403, thereby effectively preventing light leakage. Furthermore, using such materials is preferable because they feel pleasant to the touch and do not cause the user to feel cold when worn in cold seasons. It is preferable that components that come into contact with the user's skin, such as the buffer member 8403 or the mounting unit 8402, be removable for easy cleaning or replacement.

[0455] The electronic device shown in Figures 29A to 29F has a housing 9000, a display unit 9001, a speaker 9003, operation keys 9005 (including a power switch or an operation switch), a connection terminal 9006, a sensor 9007 (including the function of detecting, detecting, or measuring force, displacement, position, velocity, acceleration, angular velocity, rotation speed, distance, light, liquid, magnetism, temperature, chemical substance, sound, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, gradient, vibration, odor, or infrared rays), a microphone 9008, etc.

[0456] 29A to 29F have various functions. For example, they may have a function to display various information (still images, videos, text images, etc.) on a display unit, a touch panel function, a function to display a calendar, date, or time, a function to control processing using various software (programs), a wireless communication function, a function to read and process programs or data recorded on a recording medium, etc. Note that the functions of the electronic device are not limited to these, and the electronic device may have various other functions. The electronic device may have multiple display units. Furthermore, the electronic device may have a function to include a camera or the like to capture still images or videos and store them on a recording medium (external or built-in to the camera), a function to display the captured images on the display unit, etc.

[0457] The display device of one embodiment of the present invention can be applied to the display portion 9001 .

[0458] The electronic device shown in FIGS. 29A to 29F will be described in detail below.

[0459] FIG. 29A is a perspective view showing a mobile information terminal 9101. The mobile information terminal 9101 can be used as, for example, a smartphone. 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 thereof. FIG. 29A shows an example in which three icons 9050 are displayed. Information 9051, indicated by a dashed rectangle, can also be displayed on another surface of the display unit 9001. Examples of the information 9051 include notifications of incoming emails, SNS messages, phone calls, etc., the title of the email or SNS message, the sender's name, the date and time, the remaining battery level, and the strength of antenna reception. Alternatively, the icon 9050 or the like may be displayed in the position where the information 9051 is displayed.

[0460] 29B is a perspective view showing mobile information terminal 9102. Mobile information terminal 9102 has a function of displaying information on three or more sides of display unit 9001. Here, an example is shown in which information 9052, information 9053, and information 9054 are displayed on different sides. For example, while carrying mobile information terminal 9102 in a breast pocket of clothes, the user can check information 9053 displayed in a position that can be observed from above mobile information terminal 9102. The user can check the display without taking mobile information terminal 9102 out of the pocket and decide, for example, whether to answer a call.

[0461] FIG. 29C is a perspective view showing a wristwatch-type mobile information terminal 9200. The mobile information terminal 9200 can be used as, for example, a smart watch (registered trademark). The display surface of the display unit 9001 is curved, and display can be performed along the curved display surface. Hands-free calling is also possible by allowing the mobile information terminal 9200 to communicate with, for example, a headset capable of wireless communication. The mobile information terminal 9200 can also perform data transmission and reception with other information terminals and charge itself via a connection terminal 9006. Note that charging may be performed by wireless power supply.

[0462] 29D to 29F are perspective views showing a foldable mobile information terminal 9201. FIG. 29D shows the mobile information terminal 9201 in an unfolded state, FIG. 29F shows it in a folded state, and FIG. 29E is a perspective view showing a state in the process of changing from one of FIG. 29D and FIG. 29F to the other. The mobile information terminal 9201 is highly portable when folded, and has a seamless, wide display area when unfolded, providing excellent viewability of the display. The display unit 9001 of the mobile information terminal 9201 is supported by three housings 9000 connected by hinges 9055. For example, the display unit 9001 can be bent with a curvature radius of 0.1 mm or more and 150 mm or less.

[0463] 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.

[0464] This embodiment mode can be implemented by appropriately combining at least a part thereof with other embodiment modes described in this specification. [Example]

[0465] In this example, the results of investigating the electrical resistance between conductive layers via the EL layer 114 are shown.

[0466] In this example, nine types of samples (samples A1 to A6 and samples B1 to B3) were fabricated. Each sample had a light-emitting element and a connection portion.

[0467] The light-emitting element of each sample was formed by sequentially forming a hole injection layer, a hole transport layer, a light-emitting layer, an electron transport layer, an electron injection layer, and a common electrode on a pixel electrode formed on a glass substrate.

[0468] 30 is a cross-sectional view showing the configuration of connection portion 900 of each sample. Connection portion 900 of each sample has conductive layer 901 on a glass substrate (not shown), layer 902 on conductive layer 901, and conductive layer 903 on layer 902. Conductive layer 901 corresponds to connection electrode 111C described in embodiment 1, layer 902 corresponds to EL layer 114 described in embodiment 1, and conductive layer 903 corresponds to common electrode 113 described in embodiment 1. In other words, each sample has the configuration of connection portion 130 described in embodiment 1.

[0469] The conductive layer 901 was formed using a material that can be used for the connection electrode 111C. In this example, the conductive layer 901 had a stacked structure of an alloy film of silver (Ag), palladium (Pd), and copper (Cu) (Ag-Pd-Cu (APC) film) and an indium tin oxide (ITSO) film containing silicon oxide on the APC film. The thickness of the APC film was 100 nm, and the thickness of the ITSO film was 90 nm. The material, thickness, and deposition conditions of the conductive layer 901 were the same for Samples A1 to A6 and Samples B1 to B3.

[0470] The layer 902 was formed using a material that can be used for the EL layer 114. In this example, a lithium fluoride (LiF) film was formed as the layer 902. Note that the layers 902 were the same in Samples A1 to A6 and Samples B1 to B3 except for the thickness (materials, deposition conditions, and the like).

[0471] The samples differ in the thickness of the layer 902. Specifically, the thickness of the layer 902 was 0.1 nm for sample A2, 0.2 nm for sample A3, 0.5 nm for sample A4, 1.0 nm for samples A5 and B2, and 2.0 nm for samples A6 and B3. Note that the layer 902 was not formed in samples A1 and B1.

[0472] The conductive layer 903 was formed using a material that can be used for the common electrode 113. In this example, the conductive layer 903 had a stacked structure of an alloy film of silver and magnesium and an ITO film on the alloy film. The thickness of the alloy film was 8 nm, and the thickness of the ITO film was 200 nm. The material, thickness, and deposition conditions of the conductive layer 903 were the same for Samples A1 to A6 and Samples B1 to B3.

[0473] The samples differ in the area of ​​the region where the conductive layer 901 and the conductive layer 903 overlap with the layer 902 interposed therebetween when viewed from above. Specifically, the area of ​​the region where the conductive layer 901 and the conductive layer 903 overlap with the layer 902 interposed therebetween when viewed from above is 10.6 μm×10.6 μm (=112.36 μm) in the samples A1 to A6. 2 =0.00011236mm 2 ), and for samples B1 to B3, it was 400 μm×100 μm (=40000 μm 2 =0.04mm 2 Hereinafter, the area of ​​the region where conductive layer 901 and conductive layer 903 overlap with layer 902 interposed therebetween in a top view may be referred to as a contact area.

[0474] [Measurement results] For Samples A1 to A6 and Samples B1 to B3, the electrical resistance between the conductive layer 901 and the conductive layer 903 with the layer 902 interposed therebetween was measured. Note that the light-emitting elements of the samples all exhibited favorable element characteristics.

[0475] The measurement results of electrical resistance are shown in Figure 31. In Figure 31, the horizontal axis represents the sample name, and the vertical axis represents resistance [Ω]. The electrical resistance at the connection portion 900 of each sample was 30.5 Ω for sample A1, 43.8 Ω for sample A2, 102 Ω for sample A3, 437.3 Ω for sample A4, 3080.3 Ω for sample A5, 8519.5 Ω for sample A6, 11 Ω for sample B1, 17.5 Ω for sample B2, and 15225.8 Ω for sample B3.

[0476] The electrical resistance of sample B2 was smaller than that of sample A1. Furthermore, the electrical resistance of sample B2 was approximately the same as that of sample B1. Therefore, it was confirmed that the electrical resistance between the connection electrode 111C and the common electrode 113 via the EL layer 114 can be reduced by increasing the contact area.

[0477] As shown in Figure 31, it was found that the thinner the film thickness of the layer 902, the smaller the electrical resistance. Therefore, it was confirmed that the electrical resistance in the thickness direction of the EL layer 114 can be reduced by reducing the film thickness of the EL layer 114. In particular, if the film thickness of the EL layer 114 is less than 0.5 nm, preferably 0.2 nm or less, the contact area can be reduced to 40,000 μm 2 (0.04mm 2 ), it was confirmed that the electrical resistance in the thickness direction of the EL layer 114 can be reduced in some cases.

[0478] In this embodiment, the layer 902 is made of lithium oxide (LiO xA sample C1 was also prepared, in which a conductive layer 902 was formed. The thickness of the layer 902 was 0.5 nm. The material, thickness, and deposition conditions of the conductive layer 901 in the sample C1 were the same as those of the samples A1 to A6 and the samples B1 to B3. The material, thickness, and deposition conditions of the conductive layer 903 in the sample C1 were the same as those of the samples A1 to A6 and the samples B1 to B3. The contact area of ​​the sample C1 was 10.6 μm×10.6 μm (=112.36 μm 2 =0.0106mm×0.0106mm=0.00011236mm 2 ) was decided.

[0479] For sample C1, the electrical resistance between conductive layer 901 and conductive layer 903 via layer 902 was measured. The electrical resistance at connection portion 900 of sample C1 was 68.5 Ω. The light-emitting element of sample C1 exhibited good device characteristics.

[0480] Therefore, when lithium oxide is used as the EL layer 114, if the film thickness of the EL layer 114 is 0.5 nm or less, the contact area is 40000 μm 2 (0.04mm 2 ), it was confirmed that the electrical resistance in the thickness direction of the EL layer 114 can be reduced in some cases. [Explanation of symbols]

[0481] 20: light-emitting element, 21: lower electrode, 23: EL layer, 23a: EL layer, 23b: EL layer, 25: upper electrode, 100: display device, 100A: display device, 100B: display device, 100C: display device, 100D: display device, 100E: display device, 100F: display device, 100G: display device, 100H: display device, 100I: display device, 100J: display device, 100K: display device, 101: substrate, 102: insulating layer, 105: display area, 110: light-emitting element, 110B: light-emitting element, 110G: light-emitting element, 110R: light-emitting element, 111: pixel electrode, 111B: pixel electrode, 11 1C: connection electrode, 111G: pixel electrode, 111R: pixel electrode, 112: EL layer, 112B: EL layer, 112G: EL layer, 112Gf: EL film, 112R: EL layer, 112Rf: EL film, 113: common electrode, 114: EL layer, 115B: optical adjustment layer, 115G: optical adjustment layer, 115R: optical adjustment layer, 121: protective layer, 122: gap, 130: connection portion, 131: insulating layer, 143a: resist mask, 143b: resist mask, 143d: resist mask, 144a: sacrificial film, 144b: sacrificial film, 145a: sacrificial layer, 145b: sacrificial layer, 145c: sacrificial layer, 14 6a: protective film, 146b: protective film, 147a: protective layer, 147b: protective layer, 201: transistor, 202: transistor, 204: connecting portion, 205: transistor, 209: transistor, 210: transistor, 211: insulating layer, 212: 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: connecting layer , 243: insulating layer, 245: conductive layer, 251: conductive layer, 252: conductive 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 layer, 280: display module, 281: display unit, 282: circuit unit, 283: pixel circuit unit, 283a: pixel circuit, 284: pixel unit, 284a: pixel, 285: terminal unit, 286: wiring unit, 290: FPC, 291: substrate, 292: substrate, 301: substrate, 310: 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, 400A: display device, 400B: display device, 400C: display device, 400D: display device, 400E: display device, 401: laminated structure, 411a: pixel electrode, 411b: pixel electrode, 411c: pixel electrode, 416: protective layer, 416a: inorganic insulating layer, 416b: organic Insulating layer, 416c: inorganic insulating layer, 417: light-shielding layer, 419: resin layer, 420: substrate, 421: insulating layer, 426a: optical adjustment layer, 426b: optical adjustment layer, 426c: optical adjustment layer, 430a: light-emitting element, 430b: light-emitting element, 430c: light-emitting element, 442: adhesive layer, 443: space, 451: substrate, 452: substrate, 453: substrate, 454: substrate, 455: adhesive layer, 462: display unit, 464: circuit, 465: wiring, 466: conductive layer, 472: FPC, 473: IC, 900: connecting portion, 901: conductive layer, 902: layer, 903: conductive layer, 4411: light-emitting layer, 4412: light-emitting Optical layer, 4413: light-emitting layer, 4420: layer, 4420-1: layer, 4420-2: layer, 4430: layer, 4430-1: layer, 4430-2: layer, 4440: intermediate 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, 71 00: 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, 7400: Digital signage, 7401: Pillar, 7411: Information terminal, 8000: Camera, 8001: Housing, 8002: Display, 8003: Operation button, 8004: Shutter button, 8006: Lens,8100: Viewfinder, 8101: Housing, 8102: Display unit, 8103: Buttons, 8200: Head-mounted display, 8201: Mounting unit, 8202: Lens, 8203: Main body, 8204: Display unit, 8205: Cable, 8206: Battery, 8300: Head-mounted display, 8301: Housing, 8302: Display unit, 8304: Fixing device, 8305: Lens, 8400: Head-mounted display, 8401: Housing, 8402: Mounting unit attachment part, 8403: cushioning material, 8404: display part, 8405: lens, 9000: housing, 9001: display part, 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: mobile information terminal, 9102: mobile information terminal, 9200: mobile information terminal, 9201: mobile information terminal,

Claims

1. a display unit in which a plurality of light-emitting elements are arranged in a matrix, and a connection unit located outside the display unit; each of the plurality of light-emitting elements includes a first conductive layer having a function as a pixel electrode and a first EL layer having a region located above the pixel electrode; the connecting portion includes a second conductive layer made of the same material as the pixel electrode, a second EL layer having a region in contact with an upper surface of the second conductive layer, and a third conductive layer having a region in contact with an upper surface of the second EL layer; the second EL layer has a region located above at least two or more of the first EL layers of the plurality of light-emitting elements, the third conductive layer has a region located above at least two or more of the second EL layers of the plurality of light-emitting elements and functions as a common electrode for the plurality of light-emitting elements; the second conductive layer has a function of supplying a potential to the common electrode, the second EL layer has a region with a film thickness of 0.5 nm to 1.5 mm and contains a substance with high electron injection property; A display device, wherein, in a plan view, the second conductive layer has a region that extends along the first conductive layer that at least two of the plurality of light-emitting elements have.

2. a display unit in which a plurality of light-emitting elements are arranged in a matrix, and a connection unit located outside the display unit; each of the plurality of light-emitting elements includes a first conductive layer having a function as a pixel electrode and a first EL layer having a region located above the pixel electrode; the connecting portion includes a second conductive layer made of the same material as the pixel electrode, a second EL layer having a region in contact with an upper surface of the second conductive layer, and a third conductive layer having a region in contact with an upper surface of the second EL layer; the second EL layer has a region located above at least two or more of the first EL layers of the plurality of light-emitting elements, the third conductive layer has a region located above at least two or more of the second EL layers of the plurality of light-emitting elements and functions as a common electrode for the plurality of light-emitting elements; the second conductive layer has a function of supplying a potential to the common electrode, the second EL layer has a region with a film thickness of 0.5 nm to 1.5 mm and contains a substance with high electron injection property; the second conductive layer and the third conductive layer are electrically connected via the second EL layer; A display device, wherein, in a plan view, the second conductive layer has a region that is arranged along at least two sides of the periphery of the display unit.

3. In claim 1 or 2, The area of ​​the region where the second EL layer contacts the upper surface of the first conductive layer and also contacts the third conductive layer in the connection portion is 40000 μm ２ That's it, the display device.

4. In any one of claims 1 to 3, the first EL layer contains a light-emitting compound; The display device, wherein the second EL layer contains lithium fluoride.

5. In any one of claims 1 to 4, The connecting portion has a comb-like shape or a top surface shape having a slit. Display device.

Images