Indication device

Abstract

To provide a display device that combines high display quality and high resolution. [Solution] The display device comprises a light-emitting element and a connecting portion. The connecting portion is provided along the outer periphery of a display area on which the light-emitting element is provided. The light-emitting element comprises 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 connecting portion comprises a connecting electrode, a second EL layer on the connecting electrode, and a common electrode on the second EL layer. The second EL layer comprises a first region in contact with the connecting electrode and a second region in contact with the common electrode. In a top view, the area of ​​the region where the first region and the second region overlap is 40,000 square micrometers or more. The second EL layer has a region with a film thickness of 0.5 nm or more and 1.5 nm or less. The second EL layer contains a material with high electron injection capacity.

Description

[Technical Field]

[0001] One aspect of the present invention relates to a display device. Another aspect of the present invention relates to a method for manufacturing a display device.

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

[0003] In recent years, there has been a growing demand for higher resolution display panels. Examples of devices requiring high-resolution display panels include smartphones, tablet devices, and notebook computers. Furthermore, stationary display devices such as television sets and monitors are also demanding higher resolutions. Among the devices requiring the highest level of resolution are those used for virtual reality (VR) and augmented reality (AR).

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

[0005] For example, the basic structure of an organic EL element is such that a layer containing a light-emitting organic compound is sandwiched between a pair of electrodes. By applying a voltage to this element, light emission can be obtained from the light-emitting organic compound. A display device to which such an organic EL element is applied does not require a backlight, which was necessary in liquid crystal display devices and the like, and thus can realize a display device that is thin, lightweight, has high contrast, and consumes low power. 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

Summary of the Invention

Problems to be Solved by the Invention

[0007] One aspect of the present invention is to provide a display device that is easily capable of achieving high definition, and a method for manufacturing the same as one of the problems. One aspect of the present invention is to provide a display device that combines high display quality and high definition as one of the problems. One aspect of the present invention is to provide a display device with high contrast as one of the problems. One aspect of the present invention is to provide a highly reliable display device as one of the problems.

[0008] One aspect of the present invention is to provide a display device having a novel configuration, or a method for manufacturing a display device as one of the problems. One aspect of the present invention is to provide a method for manufacturing the above-described display device with good yield as one of the problems. One aspect of the present invention is to reduce at least one of the problems of the prior art as one of the problems.

[0009] Note that the description of these problems does not prevent the existence of other problems. Note that one aspect of the present invention does not necessarily have to solve all of these problems. Note that other problems can be extracted from the descriptions in the specification, drawings, claims, and the like. [Means for solving the problem]

[0010] One aspect of the present invention is a display device having a light-emitting element and a connecting portion. The connecting portion is provided along the outer periphery of a display area on 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 connecting portion has a connecting electrode, a second EL layer on the connecting electrode, and a common electrode on the second EL layer. The second EL layer has a first region in contact with the connecting electrode and a second region in contact with the common electrode. In a top view, the area of ​​the region where the first region and the second region overlap is 40,000 μm². 2 That concludes the explanation. The second EL layer has a region with a film thickness of 0.5 nm or more and 1.5 nm or less. The second EL layer contains a material with high electron injection capacity.

[0011] Furthermore, one aspect of the present invention is a display device having a light-emitting element and a connecting portion. The connecting portion is provided along the outer periphery of a display area on which the light-emitting element is provided. The light-emitting element has a pixel electrode, an insulating layer on the pixel electrode, a first EL layer on the pixel electrode and on the insulating layer, a second EL layer on the first EL layer, and a common electrode on the second EL layer. The connecting portion has a connecting electrode, an insulating layer on the connecting electrode, a second EL layer on the connecting electrode and on the insulating layer, and a common electrode on the second EL layer. The second EL layer has a third region in contact with the connecting electrode and a second region in contact with the common electrode through a first opening in the insulating layer. In a top view, the area of ​​the region where the third region and the second region overlap is 40,000 μm². 2 That concludes the explanation. The second EL layer has a region with a film thickness of 0.5 nm or more and 1.5 nm or less. The second EL layer contains a material with high electron injection capacity.

[0012] In the above-described display device, it is preferable that the first EL layer has a region that is in contact with the pixel electrode through a second opening in the insulating layer.

[0013] Furthermore, in the above-mentioned display device, it is preferable that the first EL layer contains a luminescent compound and the second EL layer contains lithium fluoride.

[0014] Furthermore, in the above-mentioned display device, the connecting portion preferably has a comb-like or slit-like upper surface shape. [Effects of the Invention]

[0015] According to one aspect of the present invention, it is possible to provide a display device that is easily made high-resolution, and a method for manufacturing the same. Alternatively, it is possible to provide a display device that combines high display quality and high resolution. Alternatively, it is possible to provide a display device with high contrast. Alternatively, it is possible to provide a highly reliable display device.

[0016] Furthermore, according to one aspect of the present invention, a display device having a novel configuration, or a method for manufacturing a display device, can be provided. Alternatively, a method for manufacturing the above-mentioned display device with a high yield can be provided. According to one aspect of the present invention, at least one of the problems of the prior art can be mitigated.

[0017] Furthermore, the description of these effects does not preclude the existence of other effects. Moreover, one aspect of the present invention does not necessarily have to possess all of these effects. Other effects can be extracted from the description in the specification, drawings, claims, etc. [Brief explanation of the drawing]

[0018] [Figure 1] Figures 1A to 1C show examples of the configuration of a display device. [Figure 2] Figures 2A to 2J show examples of display device configurations. [Figure 3] Figures 3A to 3C show examples of methods for manufacturing a display device. [Figure 4] Figures 4A to 4C show examples of methods for manufacturing a display device. [Figure 5] Figures 5A to 5C show examples of methods for manufacturing a display device. [Figure 6] Figures 6A to 6D show examples of methods for manufacturing a display device. [Figure 7] Figures 7A to 7C show examples of display device configurations. [Figure 8] Figure 8 shows an example of a display device configuration. [Figure 9] Figures 9A to 9C show examples of methods for manufacturing a display device. [Figure 10] Figures 10A and 10B show examples of methods for manufacturing a display device. [Figure 11] Figures 11A to 11D show examples of the configuration of a display device. [Figure 12] Figure 12 shows an example of a display device configuration. [Figure 13] Figures 13A to 13C show examples of display device configurations. [Figure 14] Figures 14A to 14C show examples of the configuration of a display device. [Figure 15] Figures 15A to 15D show examples of display device configurations. [Figure 16] Figures 16A to 16C show examples of the configuration of a display device. [Figure 17] Figures 17A to 17C show examples of display device configurations. [Figure 18] Figure 18 is a perspective view showing an example of a display device. [Figure 19] Figures 19A and 19B are cross-sectional views showing an example of a display device. [Figure 20] Figure 20A is a cross-sectional view showing an example of a display device. Figure 20B is a cross-sectional view showing an example of a transistor. [Figure 21] Figures 21A and 21B are perspective views showing an example of a display module. [Figure 22] Figure 22 is a cross-sectional view showing an example of a display device. [Figure 23] Figure 23 is a cross-sectional view showing an example of a display device. [Figure 24] Figure 24 is a cross-sectional view showing an example of a display device. [Figure 25] Figures 25A to 25D show examples of the configuration of a light-emitting element. [Figure 26] Figures 26A and 26B show examples of electronic devices. [Figure 27] Figures 27A to 27D show examples of electronic devices. [Figure 28] Figures 28A to 28F show examples of electronic devices. [Figure 29] Figures 29A to 29F show examples of electronic devices. [Figure 30] Figure 30 is a diagram illustrating the composition of the sample according to the example. [Figure 31] Figure 31 shows the measurement results for the example. [Modes for carrying out the invention]

[0019] The embodiments will be described below with reference to the drawings. However, it will be readily apparent to those skilled in the art that the embodiments can be implemented in many different ways, and their form and details can be modified in various ways without departing from the spirit and scope thereof. Accordingly, the present invention shall not be construed as being limited to the contents of the following embodiments.

[0020] In the configuration of the invention described below, the same reference numerals are used in common across different drawings for identical parts or parts having similar functions, and repeated explanations are omitted. Furthermore, when referring to similar functions, the hatch patterns are the same, and reference numerals may not be assigned.

[0021] In the figures described herein, the size of each component, the thickness of the layers, or the area may be exaggerated for clarity. Therefore, the scale is not necessarily limited to those figures.

[0022] Furthermore, ordinal numbers such as "the first," "the second," etc., used in this specification are added to avoid confusion of constituent elements and do not imply any numerical limitation.

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

[0024] In this specification, the term "EL layer" refers to a layer (also called a light-emitting layer) provided between a pair of electrodes of a light-emitting element and containing at least a light-emitting substance, or a laminate including a light-emitting layer.

[0025] In this specification, a display panel, which is one form of a display device, has the function of displaying (outputting) images or the like on its display surface. Therefore, a display panel is one form of an output device.

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

[0027] In this specification, devices fabricated using a metal mask or an FMM (Fine Metal Mask, a high-resolution metal mask) may be referred to as MM (Metal Mask) structured devices. Furthermore, in this specification, devices fabricated without using a metal mask or an FMM may be referred to as MML (Metal Maskless) structured devices.

[0028] In this specification, a structure in which different light-emitting layers are created or painted for each color of light-emitting device (here, blue (B), green (G), and red (R)) may be referred to as an SBS (Side By Side) structure. Also, in this specification, a light-emitting device capable of emitting 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] Furthermore, light-emitting devices can be broadly classified into single-structure and tandem-structure devices. A single-structure device has one light-emitting unit between a pair of electrodes, and it is preferable that this light-emitting unit includes one or more light-emitting layers. To obtain white light emission, one should select light-emitting layers such that the light emitted from each of the two or more layers is complementary in color. For example, by making the light-emitting color of the first light-emitting layer and the light-emitting color of the second light-emitting layer complementary, a configuration that emits white light as a whole can be obtained. The same applies to light-emitting devices having three or more light-emitting layers.

[0030] A tandem 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 emission, the device should be configured such that the light from the light-emitting layers of the multiple light-emitting units is combined to produce white light emission. The configuration for obtaining white light emission is the same as that for a single-structure device. In a tandem 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 aforementioned white light-emitting devices (single or tandem structure) with SBS structure light-emitting devices, SBS structure light-emitting devices can consume less power than white light-emitting devices. If you want to keep power consumption low, it is preferable to use SBS structure light-emitting devices. On the other hand, white light-emitting devices are preferable because their manufacturing process is simpler than that of SBS structure light-emitting devices, which can lead to lower manufacturing costs or higher manufacturing yields.

[0032] Furthermore, if upper and lower numerical limits are specified in this specification, configurations in which the upper and lower numerical limits can be freely combined are also disclosed.

[0033] (Embodiment 1) This embodiment describes an example of the configuration of a display device according to one aspect of the present invention, and an example of a method for manufacturing the display device.

[0034] One aspect of the present invention is a display device having light-emitting elements (also called light-emitting devices). The display device has two light-emitting elements that emit light of at least different colors. Each light-emitting element has a pair of electrodes and an EL layer between them. The light-emitting elements are preferably organic EL elements (organic electroluminescent elements). 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 differentiating EL layers between light-emitting elements of different colors, it is known that they are formed by a vapor deposition method using a shadow mask such as a metal mask. However, with this method, deviations from the design occur in the shape and position of the island-like organic film due to various influences such as the precision of the metal mask, the misalignment between the metal mask and the substrate, the deflection of the metal mask, and the spreading of the contour of the deposited film due to vapor scattering, making it difficult to achieve high resolution and high aperture ratio. For this reason, measures have been taken to artificially increase resolution (also called pixel density) by applying special pixel arrangement methods such as pentile arrangements.

[0036] One aspect of the present invention involves processing the EL layer into a fine pattern without using a shadow mask such as a metal mask. This makes it possible to realize a display device with high resolution and a large aperture ratio, which has been difficult to achieve until now. Furthermore, since the EL layer can be differentiated, it is possible to realize a display device with extremely vivid colors, high contrast, and high display quality.

[0037] Here, for simplicity, we will describe the case where the EL layers of two-color light-emitting elements are fabricated separately. First, a first EL film and a first sacrificial film (also called a mask film) are laminated and formed covering the two pixel electrodes. Next, a resist mask is formed on the first sacrificial film at a position overlapping one of the pixel electrodes (the first pixel electrode). Subsequently, the resist mask, a portion of the first sacrificial film, and a portion of the first EL film are etched. At this point, the etching is terminated when the other pixel electrode (the second pixel electrode) is exposed. As a result, a portion of the first EL film (also called the first EL layer), processed in a strip or island shape, and a portion of the sacrificial film (also called the first sacrificial layer) are formed on the first pixel electrode. In this specification, "island shape" 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, the second EL film and the second sacrificial film are laminated together. Then, a resist mask is formed in a position that overlaps with the second pixel electrode. Subsequently, 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 in the same manner as above. As a result, the first EL layer and the first sacrificial layer (also called the mask layer) are provided on the first pixel electrode, and the second EL layer and the second sacrificial layer are provided on the second pixel electrode. In this way, the first EL layer and the second EL layer can be created separately. Finally, the first and second sacrificial layers are removed, exposing the first and second EL layers, and then a common electrode is formed to create two different colored light-emitting elements.

[0039] Furthermore, by repeating the above process, it is possible to create EL layers with three or more light-emitting elements, thereby realizing a display device having three or four or more light-emitting elements.

[0040] Here, in order to supply potential to the common electrode, an electrode (also called a first electrode or connecting electrode) can be provided on the same plane as the pixel electrode, and the connecting electrode and the common electrode can be electrically connected. The connecting electrode is positioned outside the display section on which the pixels are provided. Here, in order to prevent the upper surface of the connecting electrode from being exposed to etching when the first EL film is etched, it is preferable to provide a first sacrificial layer on the connecting electrode as well. Similarly, when etching the second EL film, it is preferable to provide a second sacrificial layer on the connecting electrode. The first and second sacrificial layers provided on the connecting 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 reduce the spacing between different colored EL layers to less than 10 μm using, for example, a metal mask formation method, the above method allows for narrowing the spacing to 3 μm or less, 2 μm or less, or even 1 μm or less. For example, by using an exposure apparatus for LSIs, the spacing can be narrowed to 500 nm or less, 200 nm or less, 100 nm or less, and even 50 nm or less. This significantly reduces the area of ​​the non-emitting region that may exist between two light-emitting elements, making it possible to approach an aperture ratio of 100%. For example, an aperture ratio of 50% or more, 60% or more, 70% or more, 80% or more, and even 90% or more, can be achieved, and even less than 100%.

[0042] Furthermore, the pattern of the EL layer itself can be made extremely small compared to when a metal mask is used. Also, for example, when a metal mask is used to create different EL layers, variations in thickness occur between the center and edges of the pattern, so the effective area that can be used as an emitting region is small relative to the total area of ​​the pattern. On the other hand, with the above manufacturing method, the pattern is formed by processing a film deposited to a uniform thickness, so the thickness can be made uniform within the pattern, and even if the pattern is fine, almost the entire area can be used as an emitting region. Therefore, with the above manufacturing method, it is possible to achieve both high resolution and a high aperture ratio.

[0043] Thus, the above manufacturing method makes it possible to realize a display device that integrates fine light-emitting elements, eliminating the need to artificially increase resolution by applying special pixel arrangement methods such as the pentile method. Therefore, it is possible to realize a display device with a resolution of 500 ppi or more, 1000 ppi or more, 2000 ppi or more, 3000 ppi or more, and even 5000 ppi or more, using a so-called stripe arrangement in which R, G, and B are each arranged in one direction.

[0044] In the following section, a more specific configuration example and manufacturing method example of a display device according to one aspect of the present invention will be described with reference to the drawings.

[0045] [Configuration Example 1] Figure 1A shows a schematic top view of a display device 100 according to one embodiment of the present invention. The display device 100 has multiple red-emitting light-emitting elements 110R, green-emitting light-emitting elements 110G, and blue-emitting light-emitting elements 110B. In Figure 1A, the labels R, G, and B are added within the light-emitting area of ​​each light-emitting element to simplify the distinction between them.

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

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

[0048] It is preferable to use EL elements such as OLED (Organic Light Emitting Diode) or QLED (Quantum-dot Light Emitting Diode) as the light-emitting elements 110R, 110G, and 110B. Examples of light-emitting materials for EL elements include fluorescent materials, phosphorescent materials, and thermally activated delayed fluorescence (TADF) materials. Not only organic compounds but also inorganic compounds (such as quantum dot materials) can be used as light-emitting materials for EL elements.

[0049] Figure 1A also shows a connecting electrode 111C that is electrically connected to the common electrode 113. The connecting electrode 111C is supplied with a potential (e.g., anode potential or cathode potential) to the common electrode 113. The connecting electrode 111C is located outside the display area where the light-emitting elements 110R and the like are arranged. The common electrode 113 is also shown with a dashed line in Figure 1A.

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

[0051] Figure 1B shows cross-sections of light-emitting elements 110R, 110G, and 110B. Light-emitting element 110R has a pixel electrode 111R, an EL layer 112R, an EL layer 114, and a common electrode 113. Light-emitting element 110G has a pixel electrode 111G, an EL layer 112G, an EL layer 114, and a common electrode 113. 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 light-emitting elements 110R, 110G, and 110B. The EL layer 114 can also be called a common layer.

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

[0053] Each of the EL layers 112R, 112G, and 112B may have, in addition to a layer containing a light-emitting organic compound (light-emitting layer), one or more of the following: an electron injection layer, an electron transport layer, a hole injection layer, and a hole transport layer. The EL layer 114 may have a configuration without a light-emitting layer. For example, the EL layer 114 may have one or more of the following: an electron injection layer, an electron transport layer, a hole injection layer, and a hole transport layer.

[0054] Pixel electrodes 111R, 111G, and 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 transparent to visible light is used on either each pixel electrode or the common electrode 113, while a conductive film that is reflective is used on the other. By making each pixel electrode transparent and the common electrode 113 reflective, a bottom-emission type display device can be created. Conversely, by making each pixel electrode reflective and the common electrode 113 transparent, a top-emission type display device can be created. Furthermore, by making both each pixel electrode and the common electrode 113 transparent, a dual-emission type display device can be created.

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

[0056] Each of the EL layers 112R, 112G, and 112B has 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. The edges of the EL layers 112R, 112G, and 112B are located on the insulating layer 131.

[0057] In the following, when explaining matters common to the light-emitting element 110R, light-emitting element 110G, and light-emitting element 110B, the symbols attached to the reference numerals may be omitted, and it may be referred to simply as light-emitting element 110. Similarly, the pixel electrode 111R, pixel electrode 111G, and pixel electrode 111B may be referred to simply as pixel electrode 111. Similarly, the EL layer 112R, EL layer 112G, and EL layer 112B may be referred to simply as EL layer 112.

[0058] Furthermore, the combination of colors of light emitted by the light-emitting element 110 is not limited to those described above; for example, cyan, magenta, and yellow may also be used. In addition, although the above example shows three colors, 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, four or more, or any number of colors.

[0059] As shown in Figure 1B, a gap is provided between the two EL layers 112 with different colored light-emitting elements. It is preferable that the EL layers 112R, 112G, and 112B are arranged so that they do not touch each other. This effectively prevents current from flowing through two adjacent EL layers 112, thus preventing unintended light emission. Therefore, contrast can be enhanced, and a display device with high display quality can be realized.

[0060] As shown in Figure 1C, the EL layer 112R is formed in a strip shape so that it is continuous in the Y direction within the display area. By forming the EL layer 112R and the like in a strip shape, the space required to separate them is eliminated, and the area of ​​the non-emitting region between the light-emitting elements can be reduced, thereby increasing the aperture ratio. Although Figure 1C shows a cross-section of the light-emitting element 110R as an example, the same shape can be used for the light-emitting elements 110G and 110B.

[0061] Figure 1C also shows a connection portion 130 where the connecting 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 connecting electrode 111C, and the common electrode 113 is provided in contact with the EL layer 114. In other words, in the connection portion 130, the EL layer 114 is sandwiched between the connecting electrode 111C and the common electrode 113. In other words, the EL layer 114 has a first region in contact with the connecting electrode 111C and a second region in contact with the common electrode 113. Furthermore, an insulating layer 131 is provided covering the end of the connecting 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, as the EL layer 114, an electron injection or hole injection material with 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, is used. The EL layer 114 may be composed of a laminated structure of an electron injection layer and an electron transport layer, or a laminated structure of a hole injection layer and a hole transport layer.

[0063] Furthermore, it is preferable to increase the area of ​​the region where the connecting electrode 111C and the common electrode 113 overlap via the EL layer 114 in order to suppress the increase in electrical resistance between the connecting electrode 111C and the common electrode 113. For example, the area of ​​the region where the connecting electrode 111C and the common electrode 113 overlap via the EL layer 114 may be 10,000 μm². 2 (0.01mm 2 ) More than 20,000 μm, preferably 20,000 μm 2 (0.02mm 2 ) More preferably 40,000 μm 2 (0.04mm 2) or more. However, there is no particular limit to the upper limit of the area of ​​the region where the connecting electrode 111C and the common electrode 113 overlap via the EL layer 114. In addition, the area of ​​the region where the connecting electrode 111C and the common electrode 113 overlap via the EL layer 114 is sometimes called the contact area. Furthermore, the area of ​​the region where the connecting electrode 111C and the common electrode 113 overlap via the EL layer 114 can be rephrased as the area of ​​the region where the first region (the region where the EL layer 114 and the connecting electrode 111C are in contact) and the second region (the region where the EL layer 114 and the common electrode 113 are in contact) overlap.

[0064] As described above, the electrical resistance between the connecting electrode 111C and the common electrode 113 can be reduced to a negligible degree. Thus, the connecting electrode 111C and the common electrode 113 are electrically connected. Furthermore, when using a material with low electrical resistance as the EL layer 114, it may be possible to reduce the electrical resistance between the connecting electrode 111C and the common electrode 113 to a negligible degree by satisfying either the preferred film thickness of the EL layer 114 or the preferred area of ​​the region where the connecting electrode 111C and the common electrode 113 overlap 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). Alternatively, it can sometimes be measured using secondary ion mass spectrometry (SIMS) or EDX line analysis. For example, if the EL layer 114 has an electron injection layer and lithium fluoride (LiF) is used as the electron injection layer, the thickness of the EL layer 114 can be measured using the concentration of lithium or fluorine (concentration obtained by SIMS) at and near the interface between the EL layer 112 and the common electrode 113. Alternatively, it can be measured using the concentration of lithium or fluorine (concentration obtained by SIMS) at and near the interface between the connecting electrode 111C and the common electrode 113.

[0066] Furthermore, the area of ​​the region where the connecting electrode 111C and the common electrode 113 overlap via the EL layer 114 can sometimes be measured by observing the planar shape of the connection and its surroundings using a scanning transmission electron microscope (STEM).

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

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

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

[0070] Figures 2A to 2J show schematic top views of a display device 100 according to one embodiment of the present invention. Figure 1A can also be considered an enlarged view of the area enclosed by the dashed line in Figure 2A. The display device 100 has a display area 105 and a connection part provided outside the display area 105.

[0071] The display area 105 has a light-emitting element. This light-emitting element has a common electrode 113.

[0072] The connection portion includes a common electrode 113 and a connecting electrode 111C. The connection portion (connecting 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 it may be provided across two or more sides of the outer periphery of the display area 105.

[0073] For example, if the top surface shape of the display area 105 is rectangular (including square), the top surface shape of the connection part (connection electrode 111C) can be rectangular (Figure 2A), strip-shaped (Figure 2B), L-shaped (Figure 2C), or U-shaped (square bracket-shaped) (Figure 2D). Note that the top surface shape of the display area 105 is not limited to a rectangle; it may be a quadrilateral other than a rectangle. Even if the top surface shape of the display area 105 is a quadrilateral other than a rectangle, it is preferable to provide the connection part along the outer perimeter of the display area 105. In this case, the top surface shape of the connection part can be strip-shaped, L-shaped, U-shaped (square bracket-shaped), or V-shaped.

[0074] Furthermore, the top surface shape of the display area 105 may be a shape other than those described above. For example, the top surface shape of the display area 105 may be a polygon other than a rectangle. Figure 2E shows an example where the top surface shape of the display area 105 is a regular octagon, and Figure 2F shows an example where the top surface shape of the display area 105 is a regular dodecagon. Although Figures 2E and 2F show examples where the top surface shape of the display area 105 is a regular polygon, it may also be a polygon that is not a regular polygon, a regular polygon with rounded corners, or a polygon with rounded corners. Figure 2G shows an example where the top surface shape of the display area 105 is an octagon. Even when the top surface shape of the display area 105 is a polygon, it is preferable to provide a connection part (connection electrode 111C) along the outer circumference of the display area 105. In this case, the top surface shape of the connection part can be a strip shape, an L shape, a U shape (angle bracket shape), or a V shape, etc.

[0075] Furthermore, the top surface shape of the display area 105 may be a curved shape (including circles, ellipses, oblongs, etc.). Figure 2H shows an example where the top surface shape of the display area 105 is a circle. Even when the top surface shape of the display area 105 is a polygon, a connecting portion (connecting electrode 111C) may be provided along the outer circumference of the display area 105. In this case, the top surface shape of the connecting portion can be circular, C-shaped, U-shaped, strip-shaped, L-shaped, U-shaped (angle bracket-shaped), or V-shaped, etc.

[0076] Figures 2I and 2J show enlarged views of the area enclosed by the dashed line in Figure 2E. If the top surface shape of the display area 105 is a shape other than a rectangle, such as a quadrilateral, polygon, or curved shape, the ends of the display area 105 and the connecting electrode 111C may be straight or curved as shown in Figure 2I, or they may be stepped as shown in Figure 2J.

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

[0078] [Example of manufacturing method 1] In the following, an example of a method for manufacturing a display device according to one aspect of the present invention will be described with reference to the drawings. Here, the display device 100 shown in the above configuration example will be used as an example. Figures 3A to 6D are schematic cross-sectional views of each step in the method for manufacturing the display device illustrated below. In Figure 3A and the following, the left side shows a schematic cross-sectional view of the part indicated by the dashed line A1-A2 in Figure 1A, and the right side shows a schematic cross-sectional view of the part indicated by the dashed line B1-B2 in Figure 1A.

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

[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, dip coating, spray coating, inkjet printing, dispensing, screen printing, offset printing, doctor knife method, slit coating, roll coating, curtain coating, and knife coating.

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

[0082] There are two main methods of photolithography. One method involves forming a resist mask on the thin film to be processed, then processing the thin film by etching or other means, and removing the resist mask. The other method involves forming a photosensitive thin film, then exposing and developing it to process the thin film into the desired shape.

[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 thereof. Other light sources such as ultraviolet light, KrF laser light, or ArF laser light can also be used. Exposure may also be performed using immersion lithography. Furthermore, extreme ultraviolet (EUV) light, X-rays, etc., may be used as the light source for exposure. An electron beam can also be used instead of the light source for exposure. Using extreme ultraviolet light, X-rays, or an electron beam is preferable because it enables extremely fine processing. Note that a photomask is not required when exposure is performed by scanning a beam such as an electron beam.

[0084] For etching thin films, methods such as dry etching, wet etching, and sandblasting can be used.

[0085] [Preparation of circuit board 101] As the substrate 101, a substrate having at least sufficient heat resistance to withstand subsequent heat treatment can be used. When an insulating substrate is used as the substrate 101, glass substrates, quartz substrates, sapphire substrates, ceramic substrates, organic resin substrates, etc., can be used. In addition, semiconductor substrates such as single-crystal semiconductor substrates made of silicon, silicon carbide, etc., polycrystalline semiconductor substrates, compound semiconductor substrates such as silicon germanium, and SOI substrates can be used.

[0086] In particular, it is preferable to use a substrate 101 on which a semiconductor circuit including semiconductor elements such as transistors is formed on the semiconductor substrate or insulating substrate. It is preferable that the semiconductor circuit 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 electrode 111R, pixel electrode 111G, pixel electrode 111B, and connecting electrode 111C] Next, pixel electrodes 111R, 111G, 111B, and connection electrodes 111C are formed on the substrate 101. First, conductive films that will become the pixel electrodes and connection electrodes are deposited, a resist mask is formed by photolithography, and unnecessary parts of the conductive film are removed by etching. After that, the resist mask is removed to form the pixel electrodes 111R, 111G, 111B, and connection electrodes 111C.

[0088] When using a conductive film that is reflective to visible light as each pixel electrode, it is preferable to use a material (such as silver or aluminum) that has the highest possible reflectivity across the entire wavelength range of visible light. This not only improves the light extraction efficiency of the light-emitting element but also enhances color reproduction.

[0089] [Formation of insulating layer 131] Next, an insulating layer 131 is formed by covering the ends of the pixel electrode 111R, pixel electrode 111G, pixel electrode 111B, and connecting electrode 111C (Figure 3A). An organic insulating film or an inorganic insulating film can be used as the insulating layer 131. It is preferable that the ends of the insulating layer 131 be tapered in order to improve the step coverage of the subsequent EL film. In particular, when using an organic insulating film, it is preferable to use a photosensitive material because it is easier to control the shape of the ends depending on the exposure and development conditions.

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

[0091] The EL film 112Rf has a film containing at least a luminescent compound. In addition, it may have a structure in which one or more films functioning as electron injection layers, electron transport layers, charge generation layers, hole transport layers, or hole injection layers are laminated. The EL film 112Rf can be formed by, for example, vapor deposition, sputtering, or inkjet. However, it is not limited to these, and the above-mentioned film formation methods can be used as appropriate.

[0092] As an example, it is preferable that the EL film 112Rf be a laminated film in which a hole injection layer, a hole transport layer, an emissive layer, and an electron transport layer are stacked in this order. In this case, the EL layer 114 to be formed later can be a film having an electron injection layer. In particular, by providing an electron transport layer covering the emissive layer, it is possible to suppress damage to the emissive layer during subsequent photolithography processes, and a highly reliable light-emitting element can be manufactured. Furthermore, by 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, the junction between them can be improved, resulting in a highly efficient and reliable light-emitting element. For example, an electron-transporting organic compound 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 to form the EL film 112Rf so as not to be present on the connecting electrode 111C. For example, when forming the EL film 112Rf by vapor deposition (or sputtering), it is preferable to use a shielding mask to prevent the EL film 112Rf from being deposited on the connecting electrode 111C.

[0094] [Formation of sacrificial film 144a] Next, a sacrificial film 144a is formed by covering the EL film 112Rf. The sacrificial film 144a is also provided in contact with the upper surface of the connecting electrode 111C.

[0095] The sacrificial film 144a can be a film with high resistance to etching of each EL film, such as the EL film 112Rf, i.e., a film with a high etching selectivity ratio. Alternatively, the sacrificial film 144a can be a film with a high etching selectivity ratio with protective films, such as the protective film 146a described later. Furthermore, the sacrificial film 144a can be a film that can be removed by a wet etching method that causes minimal damage to each EL film.

[0096] As the sacrificial film 144a, for example, a metal film, alloy film, metal oxide film, semiconductor film, or inorganic film such as an inorganic insulating film can be used. The sacrificial film 144a can be formed by various film deposition methods such as sputtering, evaporation, CVD, and ALD. It is preferable to use a method that causes as little damage as possible to the substrate (especially the EL film 112Rf, etc.) when forming the sacrificial film 144a. For example, the ALD method or vacuum evaporation method can be suitably used to form the sacrificial film 144a. Furthermore, the ALD method can form the sacrificial film with less film deposition damage to the substrate compared to the sputtering method.

[0097] As the sacrificial film 144a, for example, metallic materials such as gold, silver, platinum, magnesium, nickel, tungsten, chromium, molybdenum, iron, cobalt, copper, palladium, titanium, aluminum, yttrium, zirconium, and tantalum, or alloy materials containing such metallic materials, can be used. In particular, it is preferable to use low-melting-point materials such as aluminum or silver.

[0098] Furthermore, metal oxides such as indium gallium zinc oxide (In-Ga-Zn oxide, also written as IGZO) can be used as the sacrificial film 144a. In addition, indium oxide, indium zinc oxide (In-Zn oxide), indium tin oxide (In-Sn oxide), indium titanium oxide (In-Ti oxide), indium tin zinc oxide (In-Sn-Zn oxide), indium titanium zinc oxide (In-Ti-Zn oxide), indium gallium tin zinc oxide (In-Ga-Sn-Zn oxide), etc. can be used. Alternatively, indium tin oxide containing silicon can also be used.

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

[0100] Furthermore, inorganic insulating materials such as aluminum oxide, hafnium oxide, and silicon oxide can be used as the sacrificial film 144a. Using aluminum oxide as the sacrificial film 144a is particularly preferable because it can reduce manufacturing costs. Moreover, forming an aluminum oxide film as the sacrificial film 144a using the ALD method is preferable because it can reduce damage to the substrate (especially the EL film 112Rf, etc.).

[0101] Furthermore, the sacrificial film 144a may be a single-layer structure or a multilayer structure of two or more layers. Typical examples of such multilayer structures include a two-layer structure of In-Ga-Zn oxide formed by sputtering and a silicon nitride film formed by sputtering, a two-layer structure of In-Ga-Zn oxide formed by sputtering and aluminum oxide formed by ALD, or a two-layer structure of aluminum oxide formed by ALD and In-Ga-Zn oxide formed by sputtering.

[0102] Furthermore, when forming the sacrificial film 144a by the ALD method or sputtering method, a heat deposition configuration may be used. In this configuration, it is preferable that the substrate material (in this case, the EL film 112Rf) does not deteriorate, and the substrate temperature during the deposition of the sacrificial film 144a should be 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. By using the above configuration, the adhesion between the substrate material and the sacrificial film 144a can be improved.

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

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

[0105] As the sacrificial film 144a, organic materials such as polyvinyl alcohol (PVA), polyvinyl butyral, polyvinylpyrrolidone, polyethylene glycol, polyglycerin, pullulan, water-soluble cellulose, or alcohol-soluble polyamide resin can be used.

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

[0107] The protective film 146a is used as a hard mask when etching the sacrificial film 144a later. Furthermore, the sacrificial film 144a is exposed during the subsequent processing of the protective film 146a. Therefore, a combination of films with a high etching selectivity ratio for each other is selected for the sacrificial film 144a and the protective film 146a. Thus, the film that can be used for the protective film 146a can be selected according to the etching conditions for both the sacrificial film 144a and the protective film 146a.

[0108] For example, when dry etching using a fluorine-containing gas (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, or an alloy containing molybdenum and tungsten can be used for the protective film 146a. Here, metal oxide films such as IGZO and ITO can be used as sacrificial films 144a, as they allow for a higher selectivity ratio for etching (i.e., a slower etching rate) compared to the dry etching using the above-mentioned fluorine-based gas.

[0109] However, the protective film 146a can be selected from a variety of materials depending on the etching conditions of the sacrificial film 144a and the protective film 146a. For example, it can be selected from films that can be used for the sacrificial film 144a.

[0110] Furthermore, a nitride film can be used as the protective film 146a, for example. Specifically, nitride films such as silicon nitride, aluminum nitride, hafnium nitride, titanium nitride, tantalum nitride, tungsten nitride, gallium nitride, and germanium nitride can be used.

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

[0112] Furthermore, an organic film that can be used for the EL film 112Rf, etc., may be used as the protective film 146a. For example, the same organic film used for the EL film 112Rf, the EL film that becomes the EL layer 112G, or the EL film that becomes 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 deposition apparatus to be used for both the EL film 112Rf and the protective film 146a.

[0113] [Formation of resist mask 143a] Next, a resist mask 143a is formed on the protective film 146a at a position overlapping with the pixel electrode 111R and at a position overlapping with the connecting electrode 111C, respectively (Figure 3C).

[0114] The resist mask 143a can use a resist material containing a photosensitive resin, such as a positive-type resist material or a negative-type resist material.

[0115] In this case, if a resist mask 143a is formed on the sacrificial film 144a without a protective film 146a, there is a risk that the EL film 112Rf may dissolve due to the solvent of the resist material if there are defects such as pinholes in the sacrificial film 144a. Using a protective film 146a can prevent such problems from occurring.

[0116] Furthermore, if a sacrificial film 144a is used that is less prone to 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 protective film 146a] Next, the portion of the protective film 146a not covered by the resist mask 143a is removed by etching to form a protective layer 147a. At the same time, a protective layer 147a is also formed on the connecting electrode 111C.

[0118] When etching the protective film 146a, it is preferable to use etching conditions with a high selectivity ratio 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 suppress the reduction of the pattern of the protective film 146a.

[0119] [Removal of resist mask 143a] Next, remove the resist mask 143a (Figure 4A).

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

[0121] In this case, the removal of the resist mask 143a is performed while the EL film 112Rf is covered by the sacrificial film 144a, thus suppressing the impact on the EL film 112Rf. In particular, since contact with oxygen can adversely affect the electrical properties of the EL film 112Rf, this method is suitable when etching is performed using oxygen gas, such as plasma ashing.

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

[0123] The sacrificial film 144a can be etched by wet etching or dry etching, but dry etching is preferred because it can suppress pattern reduction.

[0124] [Etching of EL film 112Rf and protective layer 147a] Next, the protective layer 147a is etched, and at the same time, a portion of the EL film 112Rf not covered by the sacrificial layer 145a is removed by etching, forming a strip-shaped EL layer 112R (Figure 4C). At the same time, the protective layer 147a on the connecting electrode 111C is also removed.

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

[0126] In particular, for etching the EL film 112Rf, it is preferable to use dry etching with an etching gas that does not contain oxygen as its main component. This suppresses the deterioration of the EL film 112Rf and enables the realization of a highly reliable display device. Examples of etching gases that do not contain oxygen as their main component include noble gases such as CF4, C4F8, SF6, CHF3, Cl2, H2O, BCl3, H2, or He. Alternatively, a mixed gas of the above gases and an oxygen-free diluent gas can be used as the etching gas.

[0127] The etching of the EL film 112Rf and the protective layer 147a may be performed 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 connecting electrode 111C are covered by the sacrificial layer 145a.

[0129] [Formation of EL film 112Gf] Next, 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, it is preferable not to provide the EL film 112Gf on the connecting electrode 111C, similar to the EL film 112Rf described above.

[0130] The method for forming the EL film 112Gf can be described by referring to the description of the EL film 112Rf above.

[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 in the same manner as the sacrificial film 144a. In particular, it is preferable to use the same material for the sacrificial film 144b as for the sacrificial film 144a.

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

[0133] [Formation of protective film 146b] Next, a protective film 146b is formed on the sacrificial film 144b. The protective film 146b can be formed in the same manner as the protective film 146a. In particular, it is preferable to use the same material for the protective film 146b as for the protective film 146a.

[0134] [Formation of resist mask 143b] Next, a resist mask 143b is formed on the protective film 146b in the region overlapping with the pixel electrode 111G and the region overlapping with the connecting electrode 111C (Figure 5A).

[0135] The resist mask 143b can be formed in the same manner as the resist mask 143a.

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

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

[0138] [Removal of resist mask 143b] Next, remove the resist mask 143b. The removal of resist mask 143b can be done by referring to the description of resist mask 143a above.

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

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

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

[0142] Etching of the EL film 112Gf and protective layer 147b can be performed by referring to the description of the EL film 112Rf and protective layer 147a above.

[0143] In this case, the EL layer 112R is protected by the sacrificial layer 145a, thus preventing it from being damaged by the etching process of the EL film 112Gf.

[0144] In this way, the strip-shaped EL layer 112R and the strip-shaped EL layer 112G can be manufactured 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, island-like EL layers 112B and island-like sacrificial layers 145c can be formed (Figure 6A).

[0146] Specifically, after the formation of the EL layer 112G, an EL film to become the EL layer 112B, a sacrificial film to become the sacrificial layer 145c, a protective film, and a resist mask are formed in sequence. Subsequently, 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. After that, the protective layer and the EL film are etched to form a strip-shaped EL layer 112B.

[0147] Furthermore, after the formation of the EL layer 112B, a sacrificial layer 145c is simultaneously formed on the connecting electrode 111C. Sacrificial layers 145a, 145b, and 145c are stacked on the connecting electrode 111C.

[0148] [Removal of the sacrificial layer] Next, sacrificial layers 145a, 145b, and 145c are removed, exposing the upper surfaces of EL layers 112R, 112G, and 112B (Figure 6B). At the same time, the upper surface of the connecting electrode 111C is also exposed.

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

[0150] Alternatively, it is preferable to remove the sacrificial layers 145a, 145b, and 145c by dissolving them in a solvent such as water or alcohol. Here, various alcohols can be used as the alcohol that can dissolve the sacrificial layers 145a, 145b, and 145c, such as ethyl alcohol, methyl alcohol, isopropyl alcohol (IPA), or glycerin.

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

[0152] In this way, EL layer 112R, EL layer 112G, and EL layer 112B can be manufactured separately.

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

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

[0155] The common electrode 113 can be formed by a film deposition method such as vapor deposition or sputtering. Alternatively, a film formed by vapor deposition and a film formed by sputtering may be laminated together.

[0156] In this case, as shown in Figure 6C, the connection portion 130 has a configuration in which the EL layer 114 is sandwiched between the connecting electrode 111C and the common electrode 113. In this case, as described above, by setting the thickness of the EL layer 114 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, the electrical resistance in the thickness direction of the EL layer 114 can be reduced.

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

[0158] Therefore, the electrical resistance between the connecting electrode 111C and the common electrode 113 can be reduced to a negligible degree. Thus, the connecting 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 Figure 6D, it is preferable to provide the protective layer 121 so as to cover the ends of the common electrode 113 and the ends of the EL layer 114. This effectively prevents the diffusion of impurities such as water or oxygen from the outside to the EL layer 114 and the interface between the EL layer 114 and the common electrode 113.

[0160] For depositing the inorganic insulating film used in the protective layer 121, sputtering, PECVD, or ALD methods are preferred. The ALD method is particularly preferred because it offers excellent step coverage and is less prone to defects such as pinholes. Furthermore, for depositing the organic insulating film, the inkjet method is preferred because it can form a uniform film in the desired area.

[0161] Based on the above, the display device 100 shown in Figures 1B and 1C can be manufactured.

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

[0163] The above is an explanation of an example of a method for manufacturing a display device.

[0164] [Configuration Example 2] The following describes a configuration example of a display device that differs in some aspects from the above Configuration Example 1. In the following sections, explanations of parts that overlap with the above may be omitted.

[0165] The display device 100A shown in Figures 7A to 7C differs from the display device 100 mainly in the shape of the EL layer 114 and the common electrode 113.

[0166] As shown in Figure 7B, in the cross-section in the X direction, the EL layer 114 and the common electrode 113 are separated between the 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 in the portion that overlaps with the insulating layer 131.

[0167] Furthermore, the protective layer 121 is provided to cover the sides 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] Furthermore, as shown in Figure 7B, a recess may be formed on a part of the upper surface of the insulating layer 131. In this case, it is preferable that the protective layer 121 is provided in contact with the surface of the recess of the insulating layer 131. This is preferable because it increases the contact area between the insulating layer 131 and the protective layer 121, thereby improving their adhesion.

[0169] Figure 7A shows the outlines of the common electrode 113 and the EL layer 114 with dashed lines. As shown in Figure 7A, the common electrode 113 and the EL layer 114 have a comb-like or slit-like upper surface shape.

[0170] The display device 100A shown in Figure 7A has a configuration in which the common electrode 113 and the EL layer 114 overlap with the connecting electrode 111C, but is not limited to this. For example, as shown in Figure 8, the display device 100B may have a configuration in which a part of the common electrode 113 and the EL layer 114 overlaps with the connecting electrode 111C. In Figure 8, the region in which the common electrode 113, the EL layer 114 and the connecting electrode 111C overlap is indicated by a diagonal line.

[0171] [Example of manufacturing method 2] The following describes an example of a method for manufacturing the display device 100A. Note that in the following, parts that overlap with the above example manufacturing method 1 will be referenced and explained in more detail. The example manufacturing method described here differs from the above example manufacturing method 1 in the steps from the formation of the common electrode 113 onwards.

[0172] Figures 9A to 10A show schematic cross-sectional diagrams of each process illustrated below. In Figure 9A and others, the left side shows a schematic cross-sectional diagram of the area indicated by the dashed line A1-A2 in Figure 7A, and the right side shows a schematic cross-sectional diagram of the area indicated by the dashed line B1-B2 in Figure 7A.

[0173] The process is carried out sequentially, similar to the above example of the manufacturing method 1, up to the formation of the common electrode 113 (Figure 9A).

[0174] Next, multiple resist masks 143d are formed on the common electrode 113 (Figure 9B). The resist masks 143d are formed to have a comb-like or slit-like top surface shape. The resist masks 143d are superimposed on the pixel electrodes 111R, 111G, 111B, and connecting electrode 111C. The resist masks 143d also have edges provided 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 (Figure 9C). As a result, slits are formed in the common electrode 113 and the EL layer 114, which were previously provided as a continuous structure covering all the pixel electrodes and connecting electrodes, by the etching process, resulting in the common electrode 113 and the EL layer 114 having a comb-like or slit-like upper surface shape.

[0176] Etching is preferably performed by dry etching. For example, it is preferable to continuously etch the common electrode 113 and the EL layer 114 in sequence without exposure to the atmosphere by switching the etching gas. Furthermore, it is preferable to use a gas that does not contain oxygen as its main component as the etching gas.

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

[0178] Next, the resist mask 143d is removed. The resist mask 143d can be removed by wet etching or dry etching.

[0179] Next, a protective layer 121 is formed (Figure 10A). The protective layer 121 is provided to cover the side surfaces of the common electrode 113, the EL layer 114, and the EL layer 112. It is also preferable that the protective layer 121 be in contact with the upper surface of the insulating layer 131.

[0180] Furthermore, as shown in Figure 10B, when the protective layer 121 is formed, a void (also called 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 also contain gases such as air, nitrogen, noble gases, or film-forming gases used for forming the protective layer 121.

[0181] The above is an explanation of an example of a method for manufacturing the display device 100A.

[0182] In this example, the resist mask 143d was directly formed on the common electrode 113, but a film functioning as a hard mask may also be provided on the common electrode 113. In this case, the hard mask can be formed using the resist mask 143d as a mask, and after removing the resist mask, the common electrode 113 and the EL layer 114 can be etched using the hard mask as a mask. The hard mask may be removed or left in place at this stage.

[0183] [Configuration Example 3] The display device 100C shown in Figures 11A to 11D differs from the display device 100 in that the shapes of the EL layer 114 and the common electrode 113 are different. Figure 11A is a schematic top view of the display device in the area enclosed by the dashed line in Figure 2A.

[0184] As shown in Figure 11C, in a cross-section in the Y direction, the EL layer 112R, EL layer 114, and common electrode 113 are separated between the two light-emitting elements 110R. In other words, the EL layer 112R, EL layer 114, and common electrode 113 have ends in the portion that overlaps with the insulating layer 131.

[0185] Furthermore, the protective layer 121 is provided to cover the sides 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] Furthermore, as shown in Figure 11C, a recess may be formed on a part of the upper surface of the insulating layer 131. In this case, it is preferable that the protective layer 121 is provided in contact with the surface of the recess of the insulating layer 131. This is preferable because it increases the contact area between the insulating layer 131 and the protective layer 121, thereby improving their adhesion.

[0187] Figure 11A shows the outlines of the common electrode 113 and the EL layer 114 with dashed lines. As shown in Figure 11A, the common electrode 113 and the EL layer 114 have a comb-like or slit-like upper surface shape. On the other hand, as shown in Figures 11B and 11C, the EL layer 112R has an island-like shape. Furthermore, as shown in Figure 11D, the connection portion 130 has the same configuration as the connection portion 130 of the display device 100.

[0188] The display device 100C shown in Figure 11A has a configuration in which the common electrode 113 and the EL layer 114 overlap with the connecting electrode 111C, but is not limited to this. For example, as shown in Figure 12, the display device 100D may have a configuration in which a part of the common electrode 113 and the EL layer 114 overlaps with the connecting electrode 111C. In Figure 12, the region in which the common electrode 113, the EL layer 114 and the connecting electrode 111C overlap is indicated by a diagonal line.

[0189] Although not shown here, the same configuration can be applied to the light-emitting element 110G and the light-emitting element 110B.

[0190] [Differentiation] The following describes an example with a slightly different structure from the one described above. Note that parts that overlap with the above will be referenced and explained in more detail below.

[0191] [Variation 1] The display device 100E shown in Figures 13A and 13B differs from the above-mentioned display device 100 mainly in the configuration of the light-emitting element.

[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 layers 115R, 115G, and 115B are all transparent to visible light. The optical adjustment layers 115R, 115G, and 115B each have different thicknesses. This allows for different optical path lengths for each light-emitting element.

[0194] Here, a conductive film reflective to visible light is used for the pixel electrodes 111R, 111G, and 111B, and a conductive film reflective and transmittant to visible light is used for the common electrode 113. As a result, each light-emitting element realizes a so-called microcavity structure (micro-resonator 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. For example, conductive oxides such as indium oxide, indium tin oxide, indium zinc oxide, zinc oxide, zinc oxide containing gallium, indium tin oxide containing silicon, and indium zinc oxide containing silicon can be used.

[0196] Each optical adjustment layer can be formed after the pixel electrodes 111R, 111G, and 111B have been formed, but before the EL film 112Rf, etc., is formed. Each optical adjustment layer may use conductive films of different thicknesses, or it may be arranged in a single-layer structure, a two-layer structure, a three-layer structure, etc., from thinnest to thickest.

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

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

[0199] Display device 100G is an example of realizing a microcavity structure by varying the thickness of the EL layer 112R, EL layer 112G, and EL layer 112B. This configuration eliminates the need for a separate optical adjustment layer, thus simplifying the manufacturing process.

[0200] For example, in the display device 100G, the EL layer 112R of the light-emitting element 110R, which emits the longest wavelength light, is the thickest, and the EL layer 112B of the light-emitting element 110B, which emits the shortest wavelength light, is the thinnest. However, this is not limited to this, and the thickness of each EL layer can be adjusted by considering the wavelength of light emitted by each light-emitting element, the optical properties of the layers constituting the light-emitting element, and the electrical properties of the light-emitting element.

[0201] Furthermore, the display device 100H shown in Figure 14C is an example in which a microcavity structure is realized by varying the thickness of the EL layer 112 of the display device 100A. Figure 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 in the X direction.

[0202] [Example 3] The display device 100I shown in Figures 15A to 15D differs from the above-mentioned display device 100 mainly in the shape of the insulating layer 131.

[0203] When an inorganic insulating film is used as the insulating layer 131 covering the ends of the pixel electrode 111 and the connecting electrode 111C, the insulating layer 131 may have recesses in areas that do not overlap with the pixel electrode 111 and the connecting electrode 111C. When an inorganic insulating film is used as the insulating layer 131, impurities are less likely to enter the light-emitting element compared to when an organic insulating film is used, which can improve the reliability of the light-emitting element.

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

[0205] By omitting the insulating layer 131, the aperture ratio can be increased. Alternatively, the distance between light-emitting elements can be reduced, which may increase the fineness or resolution of the display device.

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

[0207] The display device 100K has an insulating layer 102 on a substrate 101. Furthermore, the display device 100K has a configuration in which the pixel electrodes 111 are embedded in openings provided in the insulating layer 102. In other words, the upper surface of the pixel electrodes 111 and the upper surface of the insulating layer 102 are roughly aligned. This configuration allows the EL layer 112 to be formed on a flat surface, thereby improving the coverage of the EL layer 112.

[0208] In this specification, "approximately matching heights" refers to a configuration in which the heights from a reference surface (e.g., a flat surface such as the substrate surface) are equal in a cross-sectional view. For example, in the manufacturing process of semiconductor devices, planarization (typically CMP) may expose the surfaces of one or more layers. In this case, the surfaces subjected to CMP will have a configuration in which the heights from the reference surface are equal. Furthermore, "approximately matching heights" also includes cases where the heights are identical. However, the heights of multiple layers may differ depending on the processing apparatus, processing method, or material of the surface subjected to CMP. In this specification, this case is also treated as "approximately matching heights." For example, if there are two layers with different heights (here referred to as a first layer and a second layer) with respect to a reference surface, the difference between the height of the top surface of the first layer and the height of the top surface of the second layer being 20 nm or less is also considered "approximately matching heights."

[0209] The above is an explanation of the variations.

[0210] The configuration examples illustrated in this embodiment, and the corresponding drawings, etc., can be appropriately combined with other configuration examples or drawings, etc., at least in part.

[0211] This embodiment can be implemented in appropriate combination with other embodiments described herein, at least in part.

[0212] (Embodiment 2) This embodiment describes an example of the configuration of a display device according to one aspect of the present invention.

[0213] The display device of this embodiment can be a high-resolution display device or a large-screen display device. Therefore, the display device of this embodiment can be used in electronic devices with relatively large screens, such as television sets, desktop or notebook personal computers, computer monitors, digital signage, and large game machines such as pachinko machines, as well as in the display units of digital cameras, digital video cameras, digital photo frames, mobile phones, portable game consoles, smartphones, smartwatches, tablet devices, personal digital assistants, and audio playback devices.

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

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

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

[0217] For example, a scan line drive circuit can be used as circuit 464.

[0218] Wiring 465 has the function of supplying signals and power to the display unit 462 and the circuit 464. These signals and power are input to wiring 465 from an external source via FPC 472 or from IC 473.

[0219] Figure 18 shows an example in which IC 473 is mounted on the substrate 451 using a COG (Chip On Glass) method or COF (Chip On Film) method. IC 473 can be an IC having, for example, a scan line drive circuit or a signal line drive circuit. Note that the display device 400A and the display module may be configured without an IC. Alternatively, the IC may be mounted on an FPC using a COF method or the like.

[0220] Figure 19A shows an example of a cross-section obtained by cutting a portion of the display device 400A, including the FPC 472, a portion of the circuit 464, a portion of the display unit 462, and a portion of the area including the end.

[0221] The display device 400A shown in Figure 19A has 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, etc., between substrates 451 and 452.

[0222] The light-emitting elements 430a, 430b, and 430c can be the light-emitting elements exemplified in Embodiment 1.

[0223] Here, if the pixels of the display device have three types of subpixels that have light-emitting elements that emit different colors from each other, examples of such three subpixels include subpixels of three colors: R, G, and B; and subpixels of three colors: yellow (Y), cyan (C), and magenta (M). If there are four such subpixels, examples of such four subpixels include subpixels of four colors: R, G, B, and white (W); and subpixels of four colors: R, G, B, and Y.

[0224] The protective layer 416 and the substrate 452 are bonded together via an adhesive layer 442. For sealing the light-emitting element, a solid sealing structure or a hollow sealing structure can be applied. In Figure 19A, the 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), demonstrating the application of a hollow sealing structure. The adhesive layer 442 may be provided overlapping the light-emitting element. Alternatively, the space 443 surrounded by the substrate 452, the adhesive layer 442, and the substrate 451 may be filled with a resin different from that of the adhesive layer 442.

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

[0226] The pixel electrodes 411a, 411b, and 411c are each connected to the conductive layer 222b of the transistor 205 through an opening provided in the insulating layer 214.

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

[0228] The light emitted by the light-emitting element is directed towards the substrate 452. It is preferable to use a material with high transmittance to visible light for the substrate 452.

[0229] Both transistors 201 and 205 are formed on the substrate 451. These transistors can be manufactured using the same materials and processes.

[0230] On the substrate 451, insulating layers 211, 213, 215, and 214 are provided in this order. A portion of insulating layer 211 functions as a gate insulating layer for each transistor. A portion of insulating layer 213 functions as a gate insulating layer for each transistor. Insulating layer 215 is provided covering the transistors. Insulating layer 214 is provided covering the transistors and functions as a planarization layer. The number of gate insulating layers and insulating layers covering the transistors are not limited and may be a single layer or two or more layers, respectively.

[0231] It is preferable to use a material that does not easily allow impurities such as water and hydrogen to diffuse into at least one layer of the insulating layer covering the transistor. This allows the insulating layer to function as a barrier layer. With such a configuration, the diffusion of impurities from the outside into the transistor can be effectively suppressed, thereby improving the reliability of the display device.

[0232] It is preferable to use inorganic insulating films for insulating layer 211, insulating layer 213, and insulating layer 215. Examples of inorganic insulating films that can be used include silicon nitride film, silicon oxide nitride film, silicon oxide film, silicon nitride oxide film, aluminum oxide film, and aluminum nitride film. Alternatively, hafnium oxide film, yttrium oxide film, zirconium oxide film, gallium oxide film, tantalum oxide film, magnesium oxide film, lanthanum oxide film, cerium oxide film, and neodymium oxide film may also be used. Furthermore, two or more of the above insulating films may be laminated together.

[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 prevents impurities from entering through the organic insulating film from the edge of the display device 400A. Alternatively, the organic insulating film may be formed so that its edge is inward from 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 preferred for the insulating layer 214, which functions as a planarizing layer. Examples of materials that can be used as the organic insulating film include acrylic resins, polyimide resins, epoxy resins, polyamide resins, polyimidoamide resins, siloxane resins, benzocyclobutene resins, phenolic resins, and precursors of these resins.

[0235] In the region 228 shown in Figure 19A, an opening is formed in the insulating layer 214. This prevents impurities from entering the display unit 462 from the outside through the insulating layer 214, even when an organic insulating film is used for the insulating layer 214. Therefore, the reliability of the display device 400A can be improved.

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

[0237] The transistor structure of the display device of this embodiment is not particularly limited. For example, planar transistors, staggered transistors, inverse staggered transistors, etc., can be used. Furthermore, either a top-gate or bottom-gate transistor structure may be used. Alternatively, gates may be provided above and below the semiconductor layer in which the channel is formed.

[0238] For transistors 201 and 205, a configuration in which a semiconductor layer in which a channel is formed is sandwiched between two gates is applied. The transistor may be driven by connecting the two gates and supplying the same signal thereto. 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, or a semiconductor having crystallinity other than a single crystal (a microcrystalline semiconductor, a polycrystalline semiconductor, or a semiconductor having a crystal region in part) may be used. It is preferable to use a single crystal semiconductor or a semiconductor having crystallinity because deterioration of transistor characteristics can be suppressed.

[0240] The semiconductor layer of the transistor preferably has a metal oxide (also referred to as an oxide semiconductor). That is, it is preferable to use a transistor (hereinafter, an OS transistor) in which a metal oxide is used for a channel formation region in the display device of the present embodiment. Alternatively, the semiconductor layer of the transistor may contain silicon. Examples of silicon include amorphous silicon, crystalline silicon (such as low-temperature polysilicon, single crystal silicon, etc.).

[0241] The semiconductor layer preferably has, for example, indium, M (M is one or more selected from gallium, aluminum, silicon, boron, yttrium, tin, copper, vanadium, beryllium, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, and magnesium), and zinc. In particular, M is preferably one or more 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, it is preferable that the atomic ratio of In in the In-M-Zn oxide is equal to or greater than the atomic ratio of M. Examples of such In-M-Zn oxide atomic ratios of metal elements include compositions where In:M:Zn=1:1:1 or close to it, In:M:Zn=1:1:1.2 or close to it, In:M:Zn=2:1:3 or close to it, In:M:Zn=3:1:2 or close to it, In:M:Zn=4:2:3 or close to it, In:M:Zn=4:2:4.1 or close to it, In:M:Zn=5:1:3 or close to it, In:M:Zn=5:1:6 or close to it, In:M:Zn=5:1:7 or close to it, In:M:Zn=5:1:8 or close to it, In:M:Zn=6:1:6 or close to it, In:M:Zn=5:2:5 or close to it, and so on. Note that "close to it" compositions include 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 a similar ratio, it includes cases where, when the atomic ratio of In is 4, the atomic ratio of Ga is between 1 and 3, and the atomic ratio of Zn is between 2 and 4. Also, when describing a composition with an atomic ratio of In:Ga:Zn = 5:1:6 or a similar ratio, it includes cases where, when the atomic ratio of In is 5, the atomic ratio of Ga is greater than 0.1 and 2 or less, and the atomic ratio of Zn is between 5 and 7. Furthermore, when describing a composition with an atomic ratio of In:Ga:Zn = 1:1:1 or a similar ratio, it includes cases where, when the atomic ratio of In is 1, the atomic ratio of Ga is greater than 0.1 and 2 or less, and the atomic ratio of Zn is greater than 0.1 and 2 or less.

[0245] The transistors in circuit 464 and the transistors in display unit 462 may have the same structure or different structures. The structures of the multiple transistors in circuit 464 may all be the same or there may be two or more different structures. Similarly, the structures of the multiple transistors in display unit 462 may all be the same or there may be two or more different structures.

[0246] A connection portion 204 is provided in the region of substrate 451 where substrate 452 does not overlap. At the connection portion 204, wiring 465 is electrically connected to the FPC 472 via a conductive layer 466 and a connecting layer 242. The conductive layer 466 is shown as an example of a laminated structure consisting 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 connecting layer 242.

[0247] It is preferable to provide a light-shielding layer 417 on the surface of the substrate 452 that faces the substrate 451. Various optical components can also be arranged on the outside of the substrate 452. Examples of optical components include polarizing plates, phase difference plates, light diffusion layers (such as diffusion films), anti-reflective layers, and light-collecting films. Furthermore, an antistatic film to suppress the adhesion of dust, a water-repellent film to make it difficult for dirt to adhere, a hard coat film to suppress the occurrence of scratches during use, and an impact-absorbing layer may also be arranged on the outside of the substrate 452.

[0248] By providing a protective layer 416 that covers the light-emitting element, it is possible to suppress the ingress of impurities such as water into the light-emitting element and improve the reliability of the light-emitting element.

[0249] In the region 228 near the edge of the display device 400A, it is preferable that the insulating layer 215 and the protective layer 416 are in contact with each other through an opening in the insulating layer 214. In particular, it is preferable that the inorganic insulating film of the insulating layer 215 and the inorganic insulating film of the protective layer 416 are in contact with each other. This makes it possible to suppress the entry of impurities into the display unit 462 from the outside through the organic insulating film. Therefore, the reliability of the display device 400A can be improved.

[0250] Figure 19B shows an example where the protective layer 416 has a three-layer structure. In Figure 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 edges of the inorganic insulating layer 416a and the inorganic insulating layer 416c extend outward beyond the edge of the organic insulating layer 416b and are in contact with each other. Furthermore, the inorganic insulating layer 416a is in contact with the insulating layer 215 (inorganic insulating layer) through an opening in the insulating layer 214 (organic insulating layer). As a result, the light-emitting element can be surrounded by the insulating layer 215 and the protective layer 416, thereby increasing the reliability of the light-emitting element.

[0252] Thus, 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 edge of the inorganic insulating film extends outward more than the edge of the organic insulating film.

[0253] Substrates 451 and 452 can be made of glass, quartz, ceramic, sapphire, resin, metal, alloy, semiconductor, etc., respectively. The substrate on the side that extracts light from the light-emitting element should be made of a material that transmits the light. Using flexible materials for substrates 451 and 452 can increase the flexibility of the display device. Alternatively, a polarizing plate may be used as substrate 451 or substrate 452.

[0254] Substrates 451 and 452 can be made from polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyacrylonitrile resin, acrylic resin, polyimide resin, polymethyl methacrylate resin, polycarbonate (PC) resin, polyethersulfone (PES) resin, polyamide resin (nylon, aramid, etc.), polysiloxane resin, cycloolefin resin, polystyrene resin, polyamide-imide 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 of a thickness sufficient to provide flexibility.

[0255] Furthermore, when a circular polarizing plate is superimposed on a display device, it is preferable to use a substrate with high optical isotropy for the substrate of the display device. A substrate with high optical isotropy has low birefringence (or a small amount of birefringence).

[0256] For substrates with high optical isotropy, the absolute value of the retardation (phase difference) is preferably 30 nm or less, more preferably 20 nm or less, and even more preferably 10 nm or less.

[0257] Examples of films with high optical isotropy include triacetylcellulose (TAC, also known as cellulose triacetate) film, cycloolefin polymer (COP) film, cycloolefin copolymer (COC) film, and acrylic film.

[0258] Furthermore, when using a film as the substrate, the film may absorb water, potentially causing wrinkles or other shape changes in the display panel. Therefore, it is preferable to use a film with low water absorption for the substrate. For example, it is preferable to use a film with a water absorption rate of 1% or less, more preferable to use a film with a water absorption rate of 0.1% or less, and even more preferable to use a film with a water absorption rate of 0.01% or less.

[0259] Various types of curing adhesives can be used as the adhesive layer, including UV-curing adhesives, reaction-curing adhesives, thermosetting adhesives, and anaerobic adhesives. Examples of these adhesives include epoxy resins, acrylic resins, silicone resins, phenolic resins, polyimide resins, imide resins, PVC (polyvinyl chloride) resins, PVB (polyvinyl butyral) resins, and EVA (ethylene vinyl acetate) resins. Materials with low moisture permeability, such as epoxy resins, are particularly preferred. Two-component mixed resins may also be used. Adhesive sheets may also be used.

[0260] As the connection layer 242, an anisotropic conductive film (ACF: Anisotropic Conductive Film), an anisotropic conductive paste (ACP: Anisotropic Conductive Paste), etc. can be used.

[0261] In addition to 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 the transistor, materials that can be used for conductive layers such as various wirings and electrodes constituting the display device include metals such as aluminum, titanium, chromium, nickel, copper, yttrium, zirconium, molybdenum, silver, tantalum, and tungsten, and alloys mainly composed of these metals. Films containing these materials can be used as a single layer or in a laminated structure.

[0262] Also, as the light-transmissive conductive material, conductive oxides such as indium oxide, indium tin oxide, indium zinc oxide, zinc oxide, and zinc oxide containing gallium, or graphene can be used. Or, metal materials such as gold, silver, platinum, magnesium, nickel, tungsten, chromium, molybdenum, iron, cobalt, copper, palladium, and titanium, or alloy materials containing the metal materials can be used. Or, nitrides of the metal materials (for example, titanium nitride) may be used. When using a metal material or an alloy material (or their nitrides), it is preferably made thin enough to have light-transmittance. Also, a laminated film of the above materials can be used as the conductive layer. For example, using a laminated 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 the display device, and conductive layers (conductive layers functioning as pixel electrodes or common electrodes) of the light-emitting element.

[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 oxide nitride, silicon nitride, and aluminum oxide.

[0264] [Display device 400B] Figure 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 (Figure 18). Figure 20A shows examples of cross-sections of the display device 400B when a portion of the area including the FPC 472, a portion of the circuit 464, and a portion of the display unit 462 are cut. In Figure 20A, an example of a cross-section is shown when a portion of the display unit 462, specifically the area including the light-emitting element 430b that emits green light and the light-emitting element 430c that emits blue light, is cut. Note that explanations of parts that are the same as those of the display device 400A may be omitted.

[0265] The display device 400B shown in Figure 20A has transistors 202, 210, light-emitting elements 430b, and 430c between substrates 453 and 454.

[0266] The substrate 454 and the protective layer 416 are bonded together via an adhesive layer 442. The adhesive layer 442 is provided in overlap with the light-emitting elements 430b and 430c, respectively, and a solid encapsulation 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 method for manufacturing the display device 400B involves first bonding a fabrication substrate, on which an insulating layer 212, transistors, light-emitting elements, etc., are provided, to a substrate 454 on which a light-shielding layer 417 is provided, using an adhesive layer 442. Then, the fabrication substrate is peeled off and a substrate 453 is attached to the exposed surface, thereby transferring the components formed on the fabrication substrate to the substrate 453. It is preferable that both the substrate 453 and the substrate 454 are flexible. This increases the flexibility of the display device 400B.

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

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

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

[0272] The light emitted by the light-emitting elements 430b and 430c is emitted towards the substrate 454. It is preferable to use a material with high transmittance to visible light for the substrate 454.

[0273] A connection portion 204 is provided in the region of substrate 453 that does not overlap with substrate 454. At the connection portion 204, wiring 465 is electrically connected to FPC 472 via conductive layer 466 and 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 FPC 472 to be electrically connected via the connection layer 242.

[0274] Transistors 202 and 210 each have a conductive layer 221 that functions as a gate, an insulating layer 211 that functions as a gate insulating layer, a semiconductor layer having a channel forming region 231i and a pair of low-resistance regions 231n, a conductive layer 222a connected to one of the pair of low-resistance regions 231n, a conductive layer 222b connected to the other of the pair of low-resistance regions 231n, an insulating layer 225 that functions as a gate insulating layer, a conductive layer 223 that functions as a gate, and an insulating layer 215 covering the conductive layer 223. The insulating layer 211 is located between the conductive layer 221 and the channel forming region 231i. The insulating layer 225 is located between the conductive layer 223 and the channel forming region 231i.

[0275] The conductive layer 222a and the conductive layer 222b are each connected to the low-resistance region 231n via openings provided in the insulating layer 215. Of the conductive layer 222a and the conductive layer 222b, one functions as a source and the other functions as a drain.

[0276] Figure 20A shows an example in which the insulating layer 225 covers the top and sides of the semiconductor layer. The conductive layer 222a and conductive layer 222b are connected to the low-resistance region 231n through openings provided in the insulating layer 225 and insulating layer 215, respectively.

[0277] On the other hand, in the transistor 209 shown in Figure 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 Figure 20B can be fabricated by processing the insulating layer 225 using the conductive layer 223 as a mask. In Figure 20B, an insulating layer 215 is provided covering the insulating layer 225 and the conductive layer 223, and the conductive layers 222a and 222b are connected to the low-resistance region 231n, respectively, through openings in the insulating layer 215. Furthermore, an insulating layer 218 covering the transistor may also be provided.

[0278] The configuration examples illustrated in this embodiment, and the corresponding drawings, etc., can be appropriately combined with other configuration examples or drawings, etc., at least in part.

[0279] This embodiment can be implemented in appropriate combination with other embodiments described herein, at least in part.

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

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

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

[0283] The display module 280 has substrates 291 and 292. The display module 280 has a display unit 281. The display unit 281 is an area in the display module 280 that displays an image, and is an area in which light from each pixel provided in the pixel unit 284, which will be described later, can be seen.

[0284] Figure 21B shows a schematic perspective view illustrating the configuration of the substrate 291. On the substrate 291, a circuit section 282, a pixel circuit section 283 on the circuit section 282, and a pixel section 284 on the pixel circuit section 283 are stacked. In addition, a terminal section 285 for connecting to the FPC 290 is provided in the portion of the substrate 291 that does not overlap with the pixel section 284. The terminal section 285 and the circuit section 282 are electrically connected by a wiring section 286 composed of multiple wires.

[0285] The pixel section 284 has multiple pixels 284a arranged periodically. A magnified view of a single pixel 284a is shown on the right side of Figure 21B. Each pixel 284a has light-emitting elements 430a, 430b, and 430c, each with a different emission color. The multiple light-emitting elements may be arranged in a stripe pattern as shown in Figure 21B. A stripe pattern allows for a high-density arrangement of pixel circuits, thus providing a high-resolution display device. Furthermore, various arrangement methods such as delta and pentile patterns can be applied.

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

[0287] A single pixel circuit 283a is a circuit that controls the light emission of the three light-emitting elements of a single pixel 284a. A single pixel circuit 283a may be configured to have three circuits that control the light emission of a single light-emitting element. For example, a single pixel circuit 283a may have at least one selection transistor, one current control transistor (drive transistor), and a capacitive 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 type display device.

[0288] The circuit section 282 has circuits for driving each pixel circuit 283a of the pixel circuit section 283. For example, it is preferable to have one or both of a gate line drive circuit and a source line drive circuit. In addition, it may have at least one of the following: an arithmetic circuit, a memory circuit, and a power supply circuit.

[0289] The FPC290 functions as wiring for supplying video signals or power potential, etc., to the circuit section 282 from an external source. An IC may also be mounted on the FPC290.

[0290] The display module 280 can be configured such that one or both of the pixel circuit section 283 and the circuit section 282 are stacked on the lower side of the pixel section 284, thereby enabling an extremely high aperture ratio (effective display area ratio) of the display section 281. For example, the aperture ratio of the display section 281 can be 40% or more and less than 100%, preferably 50% or more and 95%, and more preferably 60% or more and 95%. Furthermore, it is possible to arrange the pixels 284a at an extremely high density, enabling an extremely high resolution of the display section 281. For example, it is preferable that the pixels 284a in the display section 281 are arranged with a resolution of 20000 ppi or more, preferably 3000 ppi or more, more preferably 5000 ppi or more, and even more preferably 6000 ppi or more, and with a resolution of 20000 ppi or less, or 30000 ppi or less.

[0291] Because such a display module 280 is extremely high-resolution, it can be suitably used in VR devices such as head-mounted displays, or in glasses-type AR devices. For example, even in a configuration where the display part of the display module 280 is viewed through lenses, the display module 280 has an extremely high-resolution display part 281, so even when the display part is magnified with lenses, pixels are not visible, allowing for a highly immersive display. Furthermore, the display module 280 is not limited to this, and can be suitably used in electronic devices with relatively small display parts. For example, it can be suitably used in the display part of wearable electronic devices such as wristwatches.

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

[0293] Substrate 301 corresponds to substrate 291 in Figures 21A and 21B. The laminated structure 401 from substrate 301 to insulating layer 255 corresponds to substrate 101 in Embodiment 1.

[0294] The transistor 310 is a transistor having a channel-forming region in the substrate 301. The substrate 301 can be a semiconductor substrate such as a single-crystal silicon substrate. The transistor 310 comprises a portion of the substrate 301, a conductive layer 311, a low-resistance region 312, an insulating layer 313, and an insulating layer 314. The conductive layer 311 functions as a gate electrode. The insulating layer 313 is located between the substrate 301 and the conductive layer 311 and functions as a gate insulating layer. The low-resistance region 312 is a region of the substrate 301 doped with impurities and functions as either a source or a drain. The insulating layer 314 covers the 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] Furthermore, an insulating layer 261 is provided covering the transistor 310, and a capacitance 240 is provided on the insulating layer 261.

[0297] Capacitor 240 has a conductive layer 241, a conductive layer 245, and an insulating layer 243 located between them. The conductive layer 241 functions as one electrode of the capacitor 240, the conductive layer 245 functions as the other electrode of the capacitor 240, and the insulating layer 243 functions as the dielectric of the capacitor 240.

[0298] The conductive layer 241 is provided on the insulating layer 261 and embedded in the insulating layer 254. The conductive layer 241 is electrically connected to either the source or drain of the transistor 310 by a plug 271 embedded in the insulating layer 261. The insulating layer 243 is provided covering the conductive layer 241. The conductive layer 245 is provided in the region that overlaps with the conductive layer 241 via the insulating layer 243.

[0299] An insulating layer 255 is provided covering the capacitance 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 Figure 21A.

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

[0301] [Display device 400D] The display device 400D shown in Figure 23 differs from the display device 400C mainly in its transistor configuration. Note that explanations of parts similar to those of the display device 400C may be omitted.

[0302] Transistor 320 is a transistor in which a metal oxide (also called an oxide semiconductor) is applied to the semiconductor layer where the channel is formed.

[0303] The transistor 320 has a semiconductor layer 321, an insulating layer 323, a conductive layer 324, a pair of conductive layers 325, an insulating layer 326, and a conductive layer 327.

[0304] Substrate 331 corresponds to substrate 291 in Figures 21A and 21B. The laminated structure 401 from substrate 331 to insulating layer 255 corresponds to substrate 101 in Embodiment 1. An insulating substrate or a semiconductor substrate can be used as substrate 331.

[0305] An insulating layer 332 is provided on the substrate 331. The insulating layer 332 functions as a barrier layer that prevents impurities such as water or hydrogen from diffusing from the substrate 331 to the transistor 320, and prevents oxygen from detaching from the semiconductor layer 321 to the insulating layer 332. As the insulating layer 332, for example, a film that is less susceptible to hydrogen or oxygen diffusion than a silicon oxide film can be used, such as an aluminum oxide film, a hafnium oxide film, or a silicon nitride film.

[0306] A conductive layer 327 is provided on an insulating layer 332, and an insulating layer 326 is provided covering the conductive layer 327. The conductive layer 327 functions as the first gate electrode of the transistor 320, and a portion of the insulating layer 326 functions as the first gate insulating layer. It is preferable to use an oxide insulating film, such as a silicon oxide film, for at least the portion of the insulating layer 326 that is in contact with the semiconductor layer 321. It is preferable that the upper surface of the insulating layer 326 is flattened.

[0307] The semiconductor layer 321 is provided on the insulating layer 326. Preferably, the semiconductor layer 321 has a metal oxide (also called an oxide semiconductor) film having semiconductor properties. Details of materials suitable for use in the semiconductor layer 321 will be described later.

[0308] A pair of conductive layers 325 are provided in contact with the semiconductor layer 321 and function as source and drain electrodes.

[0309] Furthermore, an insulating layer 328 is provided covering the top and side surfaces of the pair of conductive layers 325, as well as the side surfaces of the semiconductor layer 321, and an insulating layer 264 is provided on the insulating layer 328. The insulating layer 328 functions as a barrier layer to prevent impurities such as water or hydrogen from diffusing into the semiconductor layer 321 from the insulating layer 264, etc., and to prevent oxygen from detaching from the semiconductor layer 321. As the insulating layer 328, an insulating film similar to that of the insulating layer 332 can be used.

[0310] An opening is provided in the insulating layer 328 and the insulating layer 264 that reaches the semiconductor layer 321. Inside this opening, the insulating layer 323 and the conductive layer 324 are embedded, in contact with the sides of the insulating layer 264, the insulating layer 328, and the conductive layer 325, as well as the upper surface of the semiconductor layer 321. The conductive layer 324 functions as a second gate electrode, and the insulating layer 323 functions as a second gate insulating layer.

[0311] The upper surfaces of the conductive layer 324, the insulating layer 323, and the insulating layer 264 are flattened so that their heights are roughly the same, and the insulating layer 329 and insulating layer 265 are provided covering them.

[0312] Insulating layers 264 and 265 function as interlayer insulating layers. Insulating layer 329 functions as a barrier layer to prevent impurities such as water or hydrogen from diffusing into the transistor 320 from insulating layer 265, etc. As insulating layer 329, an insulating film similar to that used for insulating layers 328 and 332 can be used.

[0313] A plug 274, which is electrically connected to one of the pair of conductive layers 325, is provided so as to be embedded in the insulating layers 265, 329, and 264. Here, it is preferable that the plug 274 has a conductive layer 274a that covers the sides of the openings of the insulating layers 265, 329, 264, and 328, and a part of the upper surface of the conductive layer 325, and a conductive layer 274b that is in contact with the upper surface of the conductive layer 274a. In this case, it is preferable to use a conductive material that does not easily allow hydrogen and oxygen to diffuse as the conductive layer 274a.

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

[0315] [Display device 400E] The display device 400E shown in Figure 24 has a configuration in which a transistor 310 with a channel formed on a substrate 301 and a transistor 320 containing a metal oxide in the semiconductor layer where the channel is formed are stacked. Note that parts that are the same as those of display devices 400C and 400D may be omitted from the explanation.

[0316] An insulating layer 261 is provided covering the transistor 310, and a conductive layer 251 is provided on the insulating layer 261. An insulating layer 262 is provided covering the conductive layer 251, and a conductive layer 252 is provided on the insulating layer 262. The conductive layers 251 and 252 each function as wiring. An insulating layer 263 and an insulating layer 332 are provided covering the conductive layer 252, and a transistor 320 is provided on the insulating layer 332. An insulating layer 265 is provided covering the transistor 320, and a capacitor 240 is provided on the insulating layer 265. The capacitor 240 and the transistor 320 are electrically connected by a plug 274.

[0317] Transistor 320 can be used as a transistor constituting a pixel circuit. Transistor 310 can also be used as a transistor constituting a pixel circuit, or as a transistor constituting a drive circuit (gate line drive circuit, source line drive circuit) for driving the pixel circuit. Furthermore, transistors 310 and 320 can be used as transistors constituting various circuits such as arithmetic circuits or memory circuits.

[0318] This configuration allows for the formation of not only pixel circuits but also drive circuits and other components directly beneath the light-emitting element, making it possible to miniaturize the display device compared to cases where the drive circuits are located around the display area.

[0319] The configuration examples illustrated in this embodiment, and the corresponding drawings, etc., can be appropriately combined with other configuration examples or drawings, etc., at least in part.

[0320] This embodiment can be implemented in appropriate combination with other embodiments described herein, at least in part.

[0321] (Embodiment 4) In this embodiment, a light-emitting element (also called a light-emitting device) that can be used in a display device according to one aspect of the present invention will be described.

[0322] <Example of light-emitting element configuration> As shown in Figure 25A, the light-emitting element has an EL layer 23 between a pair of electrodes (lower electrode 21, upper electrode 25). The EL layer 23 can be composed of multiple layers, such as layer 4420, light-emitting layer 4411, and layer 4430. Layer 4420 may include, for example, a layer containing a material with high electron injection properties (electron injection layer) and a layer containing a material with high electron transport properties (electron transport layer). Light-emitting layer 4411 may include, for example, a light-emitting compound. Layer 4430 may include, for example, a layer containing a material with high hole injection properties (hole injection layer) and a layer containing a material with high hole transport properties (hole transport layer).

[0323] A configuration having a layer 4420, an emissive layer 4411, and a layer 4430 provided between a pair of electrodes can function as a single emissive unit, and in this specification, the configuration shown in Figure 25A is referred to as a single structure.

[0324] Furthermore, Figure 25B shows a modified example of the EL layer 23 of the light-emitting element 20 shown in Figure 25A. Specifically, the light-emitting element 20 shown in Figure 25B has a layer 4430-1 on the lower electrode 21, a layer 4430-2 on layer 4430-1, a light-emitting layer 4411 on layer 4430-2, a layer 4420-1 on the light-emitting layer 4411, a layer 4420-2 on layer 4420-1, and an upper electrode 25 on layer 4420-2. For example, when the lower electrode 21 is the anode and the upper electrode 25 is the cathode, layer 4430-1 functions as a hole injection layer, layer 4430-2 functions as a hole transport layer, layer 4420-1 functions as an electron transport layer, and layer 4420-2 functions as an electron injection layer. Alternatively, when the lower electrode 21 is used as the cathode and the upper electrode 25 as the anode, layer 4430-1 functions as an electron injection layer, layer 4430-2 functions as an electron transport layer, layer 4420-1 functions as a hole transport layer, and layer 4420-2 functions as a hole injection layer. This layer structure allows for efficient injection of carriers into the light-emitting layer 4411 and improves the efficiency of carrier recombination within the light-emitting layer 4411.

[0325] Furthermore, as shown in Figure 25C, a configuration in which multiple 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 Figure 25D, a configuration in which multiple 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. The intermediate layer 4440 may also be referred to as a charge generation layer. In this specification, the configuration shown in Figure 25D is referred to as a tandem structure, but it is not limited to this, and for example, a tandem structure may also be called a stacked structure. By using a tandem structure, a light-emitting element capable of high-brightness light emission can be made.

[0327] Furthermore, in Figures 25C and 25D, as shown in Figure 25B, layer 4420 and layer 4430 may be a laminated structure consisting of two or more layers.

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

[0329] The light-emitting layer preferably contains two or more light-emitting materials that emit light such as R (red), G (green), B (blue), Y (yellow), and O (orange). Alternatively, it is preferable to have two or more light-emitting materials, and for each light-emitting material to emit light that contains spectral components of two or more colors from R, G, and B.

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

[0331] A light-emitting element has at least a light-emitting layer. Furthermore, the light-emitting element may also have layers other than the light-emitting layer, such as a material with high hole injection properties, a material with high hole transport properties, a hole-blocking material, a material with high electron transport properties, an electron-blocking material, a material with high electron injection properties, or a bipolar material (a material with high electron and hole transport properties).

[0332] The light-emitting device may use either low-molecular-weight compounds or high-molecular-weight compounds, and may also contain inorganic compounds. The layers constituting the light-emitting device can be formed by methods such as vapor deposition (including vacuum deposition), transfer, printing, inkjet, and coating.

[0333] For example, a light-emitting device can have a configuration that includes one or more layers from among 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 is a layer containing a material with high hole injection capabilities. Examples of materials with high hole injection capabilities include aromatic amine compounds and composite materials containing hole transport materials and acceptor materials (electron-accepting materials).

[0335] The hole transport layer is a layer that transports holes injected from the anode to the light-emitting layer by the hole injection layer. The hole transport layer is a layer containing a hole transporting material. As the hole transporting material, a substance having a hole mobility of 1×10 -6 cm 2 / Vs or more is preferable. In addition, as long as the substance has higher hole transportability than electrons, other substances can also be used. As the hole transporting material, materials with high hole transportability such as π-electron-excessive heteroaromatic compounds (such as carbazole derivatives, thiophene derivatives, furan derivatives, etc.), aromatic amines (compounds having an aromatic amine skeleton), etc. are preferable.

[0336] The electron transport layer is a layer that transports electrons injected from the cathode to the light-emitting layer by the electron injection layer. The electron transport layer is a layer containing an electron transporting material. As the electron transporting material, a substance having an electron mobility of 1×10 -6 cm 2 / Vs or more is preferable. In addition, as long as the substance has higher electron transportability than holes, other substances can also be used. As the electron transporting material, metal complexes having a quinoline skeleton, metal complexes having a benzoquinoline skeleton, metal complexes having an oxazole skeleton, metal complexes having a thiazole skeleton, etc., in addition to oxadiazole derivatives, triazole derivatives, imidazole derivatives, oxazole derivatives, thiazole derivatives, phenanthroline derivatives, quinoline derivatives having a quinoline ligand, benzoquinoline derivatives, quinoxaline derivatives, dibenzoquinoxaline derivatives, pyridine derivatives, bipyridine derivatives, pyrimidine derivatives, and other π-electron-deficient heteroaromatic compounds containing nitrogen-containing heteroaromatic compounds and other materials with high electron transportability can be used.

[0337] The electron injection layer is a layer that injects electrons from the cathode into the electron transport layer and is a layer containing a material with high electron injection property. As the material with high electron injection property, an alkali metal, an alkaline earth metal, or their compounds can be used. As the material with high electron injection property, a composite material containing an electron transporting material and a donor material (electron donating material) can also be used.

[0338] Examples of electron injection layers include lithium, cesium, lithium fluoride (LiF), cesium fluoride (CsF), calcium fluoride (CaF2), 8-(quinolinolato)lithium (abbreviated as Liq), 2-(2-pyridyl)phenolate (abbreviated as LiPP), 2-(2-pyridyl)-3-pyridinolatritium (abbreviated as LiPPy), 4-phenyl-2-(2-pyridyl)phenolate (abbreviated as LiPPP), and lithium oxide (LiO2). x ), alkali metals such as cesium carbonate, alkaline earth metals, or compounds thereof can be used.

[0339] Alternatively, an electron-transporting material may be used as the electron injection layer described above. For example, a compound having a lone pair of electrons and an electron-deficient heteroaromatic ring can be used as the electron-transporting material. Specifically, a compound having at least one of a pyridine ring, a diazine ring (pyrimidine ring, pyrazine ring, pyridazine ring), or a triazine ring can be used.

[0340] Furthermore, it is preferable that the lowest unoccupied molecular orbital (LUMO) of an organic compound containing a lone pair of electrons is between -3.6 eV and -2.3 eV. In addition, the highest occupied molecular orbital (HOMO) level and LUMO level of an organic compound can generally be estimated by methods such as cyclic voltammetry (CV), photoelectron spectroscopy, optical absorption spectroscopy, and inverse photoelectron spectroscopy.

[0341] For example, 4,7-diphenyl-1,10-phenanthroline (abbreviated as BPhen), 2,9-bis(naphthalene-2-yl)-4,7-diphenyl-1,10-phenanthroline (abbreviated as NBPhen), diquinoxalino[2,3-a:2',3'-c]phenazine (abbreviated as HATNA), and 2,4,6-tris[3'-(pyridine-3-yl)biphenyl-3-yl]-1,3,5-triazine (abbreviated as TmPPPyTz) can be used in organic compounds containing lone pairs of electrons. NBPhen has a higher glass transition temperature (Tg) and superior heat resistance compared to BPhen.

[0342] The luminescent layer is a layer containing a luminescent material. The luminescent layer may contain one or more types of luminescent materials. Suitable luminescent materials include those exhibiting colors such as blue, purple, blue-violet, green, yellow-green, yellow, orange, and red. Furthermore, materials emitting near-infrared light may also be used as luminescent materials.

[0343] Examples of luminescent 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 (especially iridium complexes) having a 4H-triazole skeleton, 1H-triazole skeleton, imidazole skeleton, pyrimidine skeleton, pyrazine skeleton, or pyridine skeleton; organometallic complexes (especially iridium complexes) using phenylpyridine derivatives having electron-withdrawing groups as ligands; platinum complexes; and rare earth metal complexes.

[0346] The light-emitting layer may contain one or more types of organic compounds (host material, assist material, etc.) in addition to the light-emitting substance (guest material). One or more of these organic compounds may be hole-transporting materials and / or electron-transporting materials. Alternatively, one or more of these organic compounds may be bipolar materials or TADF materials.

[0347] The light-emitting layer preferably comprises, for example, a phosphorescent material and a combination of a hole-transporting material and an electron-transporting material that readily forms an excitation complex. This configuration allows for efficient emission using ExTET (Exciplex-Triplet Energy Transfer), which is energy transfer from the excitation complex to the light-emitting substance (phosphorescent material). By selecting a combination that forms an excitation complex that exhibits emission overlapping with the wavelength of the lowest-energy absorption band of the light-emitting substance, energy transfer becomes smoother, and light emission can be obtained efficiently. This configuration simultaneously achieves high efficiency, low-voltage operation, and a long lifespan for the light-emitting device.

[0348] A conductive film that transmits visible light and can be used as a cathode or anode can be formed using, for example, indium oxide, indium tin oxide containing silicon oxide (ITSO), indium zinc oxide, zinc oxide, or zinc oxide with added gallium. Metal materials such as gold, silver, platinum, magnesium, nickel, tungsten, chromium, molybdenum, iron, cobalt, copper, palladium, or titanium, alloys containing these metal materials, or nitrides of these metal materials (e.g., titanium nitride) can also be used by forming them thinly enough to be translucent. Furthermore, a laminated film of the above materials can be used as a conductive layer. For example, a laminated film of a silver-magnesium alloy with indium tin oxide or silicon-containing indium tin oxide is preferable because it enhances conductivity. Graphene may also be used.

[0349] The cathode or anode preferably uses a conductive film that reflects visible light. For example, the conductive film can be a metallic material such as aluminum, gold, platinum, silver, nickel, tungsten, chromium, molybdenum, iron, cobalt, copper, or palladium, or an alloy containing these metallic materials. Silver is preferred because it has a high reflectivity of visible light. Aluminum is also preferred because it is easy to process due to its easy etching of the electrode, and it has a high reflectivity of both visible and near-infrared light. Lanthanum, neodymium, or germanium may also be added to the above metallic materials or alloys. An alloy containing titanium, nickel, or neodymium and aluminum (aluminum alloy) may also be used. Furthermore, an alloy containing copper, palladium, magnesium, and silver may also be used. An alloy containing silver and copper is preferred because of its high heat resistance.

[0350] Alternatively, the cathode or anode may be configured by laminating a conductive metal film or metal oxide film on the conductive film that reflects visible light. This configuration can suppress oxidation or corrosion of the conductive film that reflects visible light. For example, oxidation can be suppressed by laminating a metal film or metal oxide film in contact with an aluminum film or aluminum alloy film. Examples of materials for such metal films and metal oxide films include titanium or titanium oxide. Alternatively, a conductive film that transmits visible light and a film made of a metal material may be laminated. For example, a laminated film of silver and indium tin oxide, or a laminated film of a silver-magnesium alloy and indium tin oxide can be used. Furthermore, the metal film or metal oxide film may be provided beneath the conductive film that reflects visible light.

[0351] When aluminum is used as the cathode or anode, a thickness of 40 nm or more, more preferably 70 nm or more, can be used to sufficiently increase the reflectivity of visible light and the like. Similarly, when silver is used as the cathode or anode, a thickness of 70 nm or more, more preferably 100 nm or more, can be used to sufficiently increase the reflectivity of visible light and the like.

[0352] As a conductive film having light-transmitting and reflective properties that can be used as a cathode or anode, a film can be used in which the conductive film that reflects visible light is formed to a thickness that allows visible light to pass through. Furthermore, by forming a laminated structure of the conductive film and the conductive film that transmits visible light, the conductivity or mechanical strength can be increased.

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

[0354] The electrodes constituting the light-emitting element can be formed using methods such as vapor deposition or sputtering. Alternatively, they can be formed using ejection methods such as inkjet printing, printing methods such as screen printing, or plating methods.

[0355] The configuration examples illustrated in this embodiment, and the corresponding drawings, etc., can be appropriately combined with other configuration examples or drawings, etc., at least in part.

[0356] This embodiment can be implemented in appropriate combination with other embodiments described herein, at least in part.

[0357] (Embodiment 5) This embodiment describes metal oxides (also called oxide semiconductors) that can be used in the OS transistor described in the above embodiment.

[0358] The metal oxide preferably contains at least indium or zinc. It is particularly preferable that it contains indium and zinc. In addition, it is preferable that it contains aluminum, gallium, yttrium, tin, etc. It may also contain one or more selected from boron, silicon, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, magnesium, cobalt, etc.

[0359] Furthermore, metal oxides can be formed by methods such as sputtering, chemical vapor deposition (CVD) methods including metal-organic chemical vapor deposition (MOCVD), or atomic layer deposition (ALD).

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

[0361] The crystal structure of a film or substrate can be evaluated using X-ray diffraction (XRD) spectroscopy. For example, it can be evaluated using the XRD spectrum obtained by GIXD (Grazing-Incidence XRD) measurement. The GIXD method is also known as the thin-film method or the Seemann-Bohlin method.

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

[0363] Furthermore, the crystalline structure of a film or substrate can be evaluated by the diffraction pattern (also called the nano-beam electron diffraction pattern) observed using nano-beam electron diffraction (NBED). For example, a halo is observed in the diffraction pattern of a quartz glass substrate, confirming that the quartz glass is in an amorphous state. However, in the diffraction pattern of an IGZO film deposited at room temperature, a spot-like pattern is observed instead of a halo. Therefore, it is presumed that an IGZO film deposited at room temperature is in an intermediate state, neither crystalline nor amorphous, and cannot be concluded to be in an amorphous state.

[0364] <<Oxide semiconductor structure>> It should be noted that oxide semiconductors may be classified differently from those described above when considering their structure. For example, oxide semiconductors can be divided into single-crystal oxide semiconductors and other non-single-crystal oxide semiconductors. Examples of non-single-crystal oxide semiconductors include the aforementioned CAAC-OS and nc-OS. Non-single-crystal oxide semiconductors also include polycrystalline oxide semiconductors, pseudo-amorphous oxide semiconductors (a-like OS), and amorphous oxide semiconductors.

[0365] Here, we will explain the details of the CAAC-OS, nc-OS, and a-like OS mentioned above.

[0366] [CAAC-OS] CAAC-OS is an oxide semiconductor having multiple crystalline regions, the c-axis of which is oriented in a specific direction. This specific direction is the thickness direction of the CAAC-OS film, the normal direction to the surface on which the CAAC-OS film is formed, or the normal direction to the surface of the CAAC-OS film. A crystalline region is a region with periodic atomic arrangement. If we consider the atomic arrangement as a lattice arrangement, then a crystalline region is also a region with a aligned lattice arrangement. Furthermore, CAAC-OS has regions where multiple crystalline regions are connected in the ab-plane direction, and these regions may exhibit distortion. Distortion refers to a point in the connected region where the orientation of the lattice arrangement changes between a region with a aligned lattice arrangement and another region with a aligned lattice arrangement. In short, CAAC-OS is an oxide semiconductor that is c-axis oriented and does not exhibit clear orientation in the ab-plane direction.

[0367] Each of the above-mentioned crystalline regions is composed of one or more minute crystals (crystals with a maximum diameter of less than 10 nm). When a crystalline region is composed of one minute crystal, the maximum diameter of that crystalline region will be less than 10 nm. When a crystalline region is composed of many minute crystals, the maximum diameter of that crystalline region may be around several tens of nm.

[0368] Furthermore, in In-M-Zn oxides (where element M is one or more elements selected from aluminum, gallium, yttrium, tin, titanium, etc.), CAAC-OS tends to have a layered crystalline structure (also called a layered structure) consisting of layers containing indium (In) and oxygen (hereinafter referred to as the In layer) and layers containing element M, zinc (Zn), and oxygen (hereinafter referred to as the (M,Zn) layer). Note that indium and element M are mutually substitutable. Therefore, the (M,Zn) layer may contain indium. Also, the In layer may contain element M. Also, the In layer may contain Zn. This layered structure can be observed, for example, as a lattice image in high-resolution TEM (Transmission Electron Microscope) images.

[0369] When structural analysis of a CAAC-OS film is performed using an XRD instrument, for example, out-of-plane XRD measurements using θ / 2θ scanning show a peak indicating c-axis orientation at 2θ = 31° or nearby. Note that the position of the c-axis orientation peak (value of 2θ) may vary depending on the type and composition of the metal elements constituting the CAAC-OS.

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

[0371] When the crystal region is observed from the specific direction described above, the lattice arrangement within that crystal region is based on a hexagonal lattice, but the unit cell is not necessarily a regular hexagon and may be non-regular hexagonal. Furthermore, the strain may have lattice arrangements such as pentagons or heptagons. Moreover, in CAAC-OS, clear grain boundaries cannot be observed even near the strain. In other words, it can be seen that the formation of grain boundaries is suppressed by the strain in the lattice arrangement. This is thought to be because CAAC-OS can tolerate strain due to the fact that the arrangement of oxygen atoms is not dense in the ab-plane direction, or because the bond distance between atoms changes due to the substitution of metal atoms.

[0372] A crystal structure in which clear grain boundaries are observed is called a polycrystal. Grain boundaries act as recombination centers, trapping carriers and potentially causing a decrease in transistor on-current and field-effect mobility. Therefore, CAAC-OS, in which clear grain boundaries are not observed, is one of the crystalline oxides with a suitable crystal structure for the semiconductor layer of a transistor. In addition, a structure containing Zn is preferred for the composition of CAAC-OS. For example, In-Zn oxide and In-Ga-Zn oxide are preferred because they suppress the generation of grain boundaries more than In oxide.

[0373] CAAC-OS is an oxide semiconductor with high crystallinity and no clearly defined grain boundaries. Therefore, CAAC-OS is less susceptible to the decrease in electron mobility caused by grain boundaries. Furthermore, since the crystallinity of oxide semiconductors can decrease due to the inclusion of impurities and the generation of defects, CAAC-OS can be said to be an oxide semiconductor with few impurities and defects (such as oxygen vacancies). Consequently, oxide semiconductors containing CAAC-OS have stable physical properties. Therefore, oxide semiconductors containing CAAC-OS are heat resistant and highly reliable. In addition, CAAC-OS is stable even at high temperatures (so-called thermal budget) during the manufacturing process. Therefore, using CAAC-OS in OS transistors allows for greater flexibility in the manufacturing process.

[0374] [nc-OS] nc-OS exhibits periodicity in atomic arrangement in minute regions (e.g., regions between 1 nm and 10 nm, particularly between 1 nm and 3 nm). In other words, nc-OS contains minute crystals. These minute crystals are also called nanocrystals because their size is, for example, between 1 nm and 10 nm, particularly between 1 nm and 3 nm. Furthermore, nc-OS shows no regularity in crystal orientation between different nanocrystals. Therefore, no orientation is observed throughout the film. Consequently, depending on the analytical method, nc-OS may be indistinguishable from a-like OS or amorphous oxide semiconductors. For example, when structural analysis of an nc-OS film is performed using an XRD instrument, no peaks indicating crystallinity are detected in out-of-plane XRD measurements using θ / 2θ scanning. Also, when electron diffraction (also called limited-field electron diffraction) is performed on an nc-OS film using an electron beam with a probe diameter larger than that of the nanocrystals (e.g., 50 nm or larger), a diffraction pattern resembling a halo pattern is observed. On the other hand, when electron diffraction (also called nanobeam electron diffraction) is performed on an nc-OS film using an electron beam with a probe diameter close to or smaller than the size of the nanocrystal (for example, 1 nm to 30 nm), an electron diffraction pattern may be obtained in which multiple spots are observed within a ring-shaped region centered on a direct spot.

[0375] [a-like OS] a-like OS is an oxide semiconductor having a structure between nc-OS and amorphous oxide semiconductors. a-like OS has porous or low-density regions. That is, a-like OS has lower crystallinity compared to nc-OS and CAAC-OS. Also, a-like OS has a higher hydrogen concentration in the film compared to nc-OS and CAAC-OS.

[0376] <<Oxide Semiconductor Composition>> Next, we will explain the details of CAC-OS mentioned above. Note that CAC-OS refers to the material composition.

[0377] [CAC-OS] CAC-OS is a material composition in which, for example, the elements constituting the metal oxide are unevenly distributed in sizes of 0.5 nm to 10 nm, preferably 1 nm to 3 nm, or close to that size. In the following, a state in which one or more metal elements are unevenly distributed in a metal oxide, and the regions containing these metal elements are mixed in sizes of 0.5 nm to 10 nm, preferably 1 nm to 3 nm, or close to that size, is also referred to as a mosaic or patchy state.

[0378] Furthermore, CAC-OS is a composite metal oxide having a mosaic-like structure formed by the separation of the material into a first region and a second region, with the first region distributed within the film (hereinafter also referred to as a cloud-like structure). In other words, CAC-OS is a composite metal oxide having a structure in which the first region and the second region are mixed.

[0379] Here, the atomic ratios of In, Ga, and Zn to the metal elements constituting the CAC-OS in In-Ga-Zn oxide are denoted as [In], [Ga], and [Zn], respectively. For example, in the CAC-OS of In-Ga-Zn oxide, the first region is the region where [In] is greater than the [In] in the composition of the CAC-OS film. The second region is the region where [Ga] is greater than the [Ga] in the composition of the CAC-OS film. Alternatively, for example, the first region is the region where [In] is greater than the [In] in the second region, and [Ga] is smaller than the [Ga] in the second region. The second region is the region where [Ga] is greater than the [Ga] in the first region, and [In] is smaller than the [In] in the first region.

[0380] Specifically, the first region described above is a region whose main components are indium oxide, indium zinc oxide, etc. The second region described above is a region whose main components are gallium oxide, gallium zinc oxide, etc. In other words, the first region can be rephrased as a region whose main component is In. Similarly, the second region can be rephrased as a region whose main component is Ga.

[0381] Furthermore, a clear boundary may not be observed between the first region and the second region described above.

[0382] Furthermore, CAC-OS in In-Ga-Zn oxide refers to a material composition containing In, Ga, Zn, and O, in which regions with Ga as the main component and regions with In as the main component are arranged in a mosaic-like manner, with these regions existing randomly. Therefore, it is presumed that CAC-OS has a structure in which metal elements are unevenly distributed.

[0383] CAC-OS can be formed by sputtering, for example, under conditions where the substrate is not intentionally heated. When forming CAC-OS by sputtering, one or more gases selected from inert gases (typically argon), oxygen gas, and nitrogen gas may be used as the deposition gas. Furthermore, a lower ratio of the oxygen gas flow rate to the total deposition gas flow rate during deposition is preferable. For example, it is preferable that the oxygen gas flow rate ratio to the total deposition gas flow rate during deposition be 0% or more and less than 30%, preferably 0% or more and 10% or less.

[0384] Furthermore, for example, in the case of CAC-OS in In-Ga-Zn oxide, EDX mapping obtained using energy dispersive X-ray spectroscopy (EDX) confirms that it has a structure in which regions mainly composed of In (first region) and regions mainly composed of Ga (second region) are unevenly distributed and mixed.

[0385] Here, the first region is a region with higher conductivity compared to the second region. In other words, the conductivity of the metal oxide is exhibited when carriers flow through the first region. Therefore, a high field-effect mobility (μ) can be achieved when the first region is distributed in a cloud-like manner within the metal oxide.

[0386] On the other hand, the second region is a region with higher insulating properties compared to the first region. In other words, the distribution of the second region within the metal oxide can suppress leakage current.

[0387] Therefore, when CAC-OS is used in a transistor, the conductivity due to the first region and the insulation due to the second region work complementaryly to give CAC-OS a switching function (on / off function). In other words, CAC-OS has conductive function in part of the material, insulating function in part of the material, and semiconductor function as a whole. By separating the conductive function and the insulating function, both functions can be maximized. Therefore, by using CAC-OS in a transistor, a high on-current (I on ), high field-effect mobility (μ), and good switching operation can be achieved.

[0388] Furthermore, transistors using CAC-OS offer high reliability. Therefore, CAC-OS is ideal for various semiconductor devices, including display devices.

[0389] Oxide semiconductors can take on diverse structures, each possessing different properties. One embodiment of the present invention may include two or more of the following: amorphous oxide semiconductors, polycrystalline oxide semiconductors, a-like OS, CAC-OS, nc-OS, and CAAC-OS.

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

[0391] By using the above-mentioned oxide semiconductor in transistors, it is possible to realize transistors with high field-effect mobility. Furthermore, it is possible to realize highly reliable transistors.

[0392] It is preferable to use an oxide semiconductor with a low carrier concentration for the transistor. For example, the carrier concentration of an oxide semiconductor is 1 × 10⁻⁶. 17 cm -3 The following is preferably 1 × 10 15 cm -3 More preferably 1 × 10 13 cm -3More preferably 1 × 10 11 cm -3 More preferably 1 × 10 10 cm -3 It is less than 1 × 10 -9 cm -3 This concludes the explanation. Furthermore, when lowering the carrier concentration of an oxide semiconductor film, the impurity concentration in the oxide semiconductor film should be lowered to reduce the defect level density. In this specification, a low impurity concentration and low defect level density are referred to as high-purity intrinsic or substantially high-purity intrinsic. Note that oxide semiconductors with low carrier concentrations are sometimes referred to as high-purity intrinsic or substantially high-purity intrinsic oxide semiconductors.

[0393] Furthermore, oxide semiconductor films that are highly intrinsic or substantially highly intrinsic may have a low trap level density due to their low defect level density.

[0394] Furthermore, charges trapped in the trap levels of oxide semiconductors can take a long time to disappear, sometimes behaving like fixed charges. Therefore, transistors in which channel formation regions are formed in oxide semiconductors with a high trap level density may exhibit unstable electrical properties.

[0395] Therefore, reducing the impurity concentration in the oxide semiconductor is effective in stabilizing the electrical characteristics of the transistor. Furthermore, in order to reduce the impurity concentration in the oxide semiconductor, it is preferable to also reduce the impurity concentration in adjacent films. Examples of impurities include hydrogen, nitrogen, alkali metals, alkaline earth metals, iron, nickel, and silicon.

[0396] <Impurities> Here, we will explain the effects of various impurities in oxide semiconductors.

[0397] In oxide semiconductors, the presence of silicon or carbon, which are Group 14 elements, leads to the formation of defect levels in the oxide semiconductor. Therefore, the concentration of silicon or carbon in the oxide semiconductor and the concentration of silicon or carbon near the interface with the oxide semiconductor (concentration obtained by secondary ion mass spectrometry (SIMS)) are compared by 2 × 10⁻⁶. 18 atoms / cm 3 The following is preferably 2 × 10 17 atoms / cm 3 The following applies:

[0398] Furthermore, if an oxide semiconductor contains alkali metals or alkaline earth metals, it may form defect levels and generate carriers. Therefore, transistors using oxide semiconductors containing alkali metals or alkaline earth metals tend to exhibit normally-on characteristics. For this reason, the concentration of alkali metals or alkaline earth metals in the oxide semiconductor obtained by SIMS should be set to 1 × 10⁻⁶. 18 atoms / cm 3 The following is preferably 2 × 10 16 atoms / cm 3 Do the following:

[0399] Furthermore, in oxide semiconductors, the presence of nitrogen generates electrons, which act as carriers, increasing the carrier concentration and making it easier for the semiconductor to become n-type. As a result, transistors using oxide semiconductors containing nitrogen tend to exhibit normally-on characteristics. Alternatively, the presence of nitrogen in oxide semiconductors can lead to the formation of trap levels. As a result, the electrical properties of the transistor may become unstable. For this reason, the nitrogen concentration in oxide semiconductors obtained by SIMS should be set to 5 × 10⁻⁶. 19 atoms / cm 3 Less than 5 × 10 18 atoms / cm 3 More preferably 1 × 10 18 atoms / cm 3 More preferably 5 × 10 17 atoms / cm 3 Do the following:

[0400] Furthermore, hydrogen contained in oxide semiconductors can react with oxygen bonded to metal atoms to form water, potentially creating oxygen vacancies. Hydrogen can then fill these vacancies, generating electrons, which act as carriers. Additionally, some of the hydrogen can combine with oxygen bonded to metal atoms to generate electrons. Therefore, transistors using oxide semiconductors containing hydrogen tend to exhibit normally-on characteristics. For this reason, it is preferable to reduce the hydrogen content in oxide semiconductors as much as possible. Specifically, in oxide semiconductors, the hydrogen concentration obtained by SIMS should be 1 × 10⁻⁶. 20 atoms / cm 3 Less than 1 × 10 19 atoms / cm 3 Less than 5x10 18 atoms / cm 3 Less than 1 × 10 18 atoms / cm 3 Make it less than.

[0401] By using an oxide semiconductor with sufficiently reduced impurities in the channel formation region of a transistor, stable electrical characteristics can be provided.

[0402] This embodiment can be implemented in appropriate combination with other embodiments described herein, at least in part.

[0403] (Embodiment 6) In this embodiment, an electronic device according to one aspect of the present invention will be described with reference to Figures 26 to 29.

[0404] The electronic device of this embodiment has a display device according to one aspect of the present invention. The display device according to one aspect of the present invention is easily made high-definition, high-resolution, and large-scale. Therefore, the display device according to one aspect of the present invention can be used in the display units of various electronic devices.

[0405] Furthermore, since the display device according to one aspect of the present invention can be manufactured at a low cost, the manufacturing cost of electronic devices can be reduced.

[0406] Examples of electronic devices include television sets, desktop or notebook personal computers, computer monitors, digital signage, and large game machines such as pachinko machines, as well as other electronic devices with relatively large screens, digital cameras, digital video cameras, digital photo frames, mobile phones, portable game consoles, personal digital assistants, and audio playback devices.

[0407] In particular, a display device according to one aspect of the present invention can be used suitably in electronic devices having a relatively small display area because it can increase resolution. Examples of such electronic devices include information terminals (wearable devices) such as wristwatches and bracelets, as well as wearable devices that can be worn on the head, such as VR devices such as head-mounted displays and AR devices such as glasses. Wearable devices also include devices for SR and MR.

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

[0409] The electronic device of this embodiment can be incorporated along the curved surfaces of the interior or exterior walls of a house or building, or the interior or exterior of an automobile.

[0410] The electronic device in this embodiment may have an antenna. By receiving signals with the antenna, the display unit can display images and information. Furthermore, if the electronic device has an antenna and a secondary battery, the antenna may be used for contactless power transmission.

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

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

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

[0414] The electronic device 6500 includes a housing 6501, a display unit 6502, a power button 6503, a button 6504, a speaker 6505, a microphone 6506, a camera 6507, and a light source 6508, etc. The display unit 6502 has a touch panel function.

[0415] A display device according to one aspect of the present invention can be applied to the display unit 6502.

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

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

[0418] The protective member 6510 is fixed to the display panel 6511, the optical member 6512, and the touch sensor panel 6513 by an adhesive layer (not shown).

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

[0420] A flexible display (a display device with flexibility) according to one embodiment of the present invention can be applied to the display panel 6511. As a result, an extremely lightweight electronic device can be realized. Furthermore, because the display panel 6511 is extremely thin, a large-capacity battery 6518 can be installed while keeping the thickness of the electronic device low. In addition, by folding back a part of the display panel 6511 and placing the connection part with the FPC 6515 on the back of the pixel area, an electronic device with a narrow bezel can be realized.

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

[0422] A display device according to one embodiment of the present invention can be applied to the display unit 7000.

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

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

[0425] Figure 27B shows an example of a notebook personal computer. The notebook personal computer 7200 has a casing 7211, a keyboard 7212, a pointing device 7213, an external connection port 7214, etc. A display unit 7000 is incorporated into the casing 7211.

[0426] A display device according to one embodiment of the present invention can be applied to the display unit 7000.

[0427] Figures 27C and 27D show examples of digital signage.

[0428] The digital signage 7300 shown in Figure 27C comprises a housing 7301, a display unit 7000, and a speaker 7303, etc. Furthermore, it may include LED lamps, operation keys (including a power switch or operation switches), connection terminals, various sensors, a microphone, etc.

[0429] Figure 27D shows a digital signage 7400 mounted on a cylindrical column 7401. The digital signage 7400 has a display unit 7000 that is provided along the curved surface of the column 7401.

[0430] In Figures 27C and 27D, a display device according to one embodiment of the present invention can be applied to the display unit 7000.

[0431] The larger the display area 7000, the more information can be provided at once. Furthermore, a larger display area 7000 is more eye-catching, which can, for example, enhance the effectiveness of advertising.

[0432] Applying a touch panel to the display unit 7000 is preferable because it not only allows images or videos to be displayed on the display unit 7000, but also enables intuitive operation by the user. Furthermore, when used for purposes such as providing route information or traffic information, intuitive operation can enhance usability.

[0433] Furthermore, as shown in Figures 27C and 27D, it is preferable that the digital signage 7300 or digital signage 7400 can be linked wirelessly with an information terminal 7311 or information terminal 7411 such as a smartphone owned by the user. For example, the advertising information displayed on the display unit 7000 can be displayed on the screen of the information terminal 7311 or information terminal 7411. Also, the display on the display unit 7000 can be switched by operating the information terminal 7311 or information terminal 7411.

[0434] Furthermore, the digital signage 7300 or digital signage 7400 can be used to run games using the screen of the information terminal 7311 or information terminal 7411 as the control device (controller). This allows a large number of users to participate in and enjoy the game simultaneously.

[0435] Figure 28A shows the external 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 also attached to the camera 8000. The lens 8006 and the housing of the camera 8000 may be integrated into a single unit.

[0437] Camera 8000 can take an image by pressing the shutter button 8004 or by touching the display unit 8002, which functions as a touch panel.

[0438] The housing 8001 has a mount with electrodes, and in addition to the viewfinder 8100, a strobe device and the like can be connected to it.

[0439] The viewfinder 8100 includes a housing 8101, a display unit 8102, buttons 8103, etc.

[0440] The housing 8101 is attached to the camera 8000 by a mount that engages with the camera 8000's mount. The viewfinder 8100 can display images and other data received from the camera 8000 on the display unit 8102.

[0441] Button 8103 functions as a power button, etc.

[0442] A display device according to one embodiment of the present invention can be applied to the display unit 8002 of the camera 8000 and the display unit 8102 of the viewfinder 8100. The camera 8000 may also have a built-in viewfinder.

[0443] Figure 28B shows the external appearance of the head-mounted display 8200.

[0444] The head-mounted display 8200 includes a mounting section 8201, lenses 8202, a main unit 8203, a display unit 8204, a cable 8205, etc. The mounting section 8201 also has a built-in battery 8206.

[0445] Cable 8205 supplies power from battery 8206 to main unit 8203. Main unit 8203 is equipped with a wireless receiver and can display received video information on display unit 8204. In addition, main unit 8203 is equipped with a camera and can use information about the user's eyeball or eyelid movements as an input means.

[0446] Furthermore, the attachment unit 8201 may be provided with multiple electrodes at a position that touches the user, capable of detecting the current flowing in accordance with the user's eye movements, and may have a function to recognize the user's gaze. It may also have a function to monitor the user's pulse rate based on the current flowing through the electrodes. In addition, the attachment unit 8201 may have various sensors such as a temperature sensor, a pressure sensor, and an acceleration sensor, and may have a function to display the user's biometric information on the display unit 8204, or a function to change the image displayed on the display unit 8204 in accordance with the user's head movements.

[0447] A display device according to one aspect of the present invention can be applied to the display unit 8204.

[0448] Figures 28C to 28E show the external appearance of the head-mounted display 8300. The head-mounted display 8300 includes a housing 8301, a display unit 8302, a band-shaped fixing device 8304, and a pair of lenses 8305.

[0449] The user can view the display on the display unit 8302 through the lens 8305. It is preferable to position the display unit 8302 in a curved shape, as this allows the user to experience a greater sense of presence. Furthermore, by viewing different images displayed in different areas of the display unit 8302 through the lens 8305, three-dimensional display using parallax can be performed. Note that the configuration is not limited to a single display unit 8302; two display units 8302 may be provided, with one display unit for each of the user's eyes.

[0450] A display device according to one embodiment of the present invention can be applied to the display unit 8302. The display device according to one embodiment of the present invention can also achieve extremely high resolution. For example, even when the display is magnified and viewed using the lens 8305 as shown in Figure 28E, the pixels are difficult for the user to see. In other words, the display unit 8302 can be used to allow the user to view a highly realistic image.

[0451] Figure 28F shows the external appearance of a goggle-type head-mounted display 8400. The head-mounted display 8400 has a pair of housings 8401, a mounting part 8402, and a cushioning member 8403. A display unit 8404 and a lens 8405 are provided inside each of the pair of housings 8401. By displaying different images on the pair of display units 8404, a three-dimensional display using parallax can be performed.

[0452] The user can view the display unit 8404 through the lens 8405. The lens 8405 has a focusing mechanism, which allows the position of the lens 8405 to be adjusted according to the user's eyesight. The display unit 8404 is preferably a square or a horizontally elongated rectangle. This can enhance the sense of realism.

[0453] The mounting portion 8402 is preferably adjustable to the size of the user's face and has plasticity and elasticity to prevent it from slipping off. Furthermore, it is preferable that a part of the mounting portion 8402 has a vibration mechanism that functions as a bone conduction earphone. This eliminates the need for separate audio equipment such as earphones or speakers, allowing users to enjoy video and audio simply by wearing the device. The housing 8401 may also have a function to output audio data via wireless communication.

[0454] The mounting portion 8402 and the cushioning member 8403 are parts that come into contact with the user's face (forehead, cheeks, etc.). By ensuring that the cushioning member 8403 is in close contact with the user's face, light leakage can be prevented, thereby enhancing the sense of immersion. It is preferable to use a soft material for the cushioning member 8403 so that it adheres closely to the user's face when the user wears the head-mounted display 8400. For example, materials such as rubber, silicone rubber, urethane, and sponge can be used. Furthermore, if the surface of a sponge or similar material is covered with cloth, leather (genuine leather or synthetic leather), gaps are less likely to form between the user's face and the cushioning member 8403, effectively preventing light leakage. In addition, using such materials is preferable because it feels good against the skin and does not make the user feel cold when worn in cold seasons. It is preferable that the components that come into contact with the user's skin, such as the cushioning member 8403 or the mounting portion 8402, are removable, as this makes cleaning or replacement easier.

[0455] The electronic equipment shown in Figures 29A to 29F includes a housing 9000, a display unit 9001, a speaker 9003, operation keys 9005 (including a power switch or operation switch), connection terminals 9006, sensors 9007 (including functions for detecting, detecting, or measuring force, displacement, position, velocity, acceleration, angular velocity, rotational speed, distance, light, liquid, magnetism, temperature, chemical substances, sound, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, gradient, vibration, odor, or infrared radiation), a microphone 9008, etc.

[0456] The electronic devices shown in Figures 29A to 29F have various functions. For example, they may have functions 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 by various software (programs), a wireless communication function, a function to read and process programs or data recorded on a recording medium, etc. However, the functions of electronic devices are not limited to these and can have various functions. Electronic devices may have multiple display units. Furthermore, electronic devices may be equipped with a camera, etc., and have functions to capture still images or videos and save them to a recording medium (external or built into the camera), a function to display the captured images on a display unit, etc.

[0457] A display device according to one embodiment of the present invention can be applied to the display unit 9001.

[0458] Details of the electronic equipment shown in Figures 29A to 29F will be explained below.

[0459] Figure 29A is a perspective view showing a personal digital assistant (PDA) 9101. The PDA 9101 can be used, for example, as a smartphone. The PDA 9101 may also be equipped with a speaker 9003, connection terminals 9006, sensors 9007, etc. The PDA 9101 can also display text and image information on multiple surfaces. Figure 29A shows an example where three icons 9050 are displayed. Information 9051, indicated by a dashed rectangle, can also be displayed on other surfaces of the display unit 9001. Examples of information 9051 include notifications of incoming emails, SNS messages, and phone calls, the subject of emails and SNS messages, the sender's name, date and time, battery level, and antenna signal strength. Alternatively, icons 9050 or the like may be displayed in the location where the information 9051 is displayed.

[0460] Figure 29B is a perspective view showing the personal digital assistant (PDA) 9102. The PDA 9102 has the function of displaying information on three or more sides of the display unit 9001. Here, an example is shown in which information 9052, information 9053, and information 9054 are displayed on different sides. For example, a user can check information 9053, which is displayed in a position that can be observed from above the PDA 9102, while the PDA 9102 is stored in the breast pocket of their clothing. The user can check the display without taking the PDA 9102 out of their pocket and decide, for example, whether or not to answer a call.

[0461] Figure 29C is a perspective view showing a wristwatch-type personal information terminal 9200. The personal information terminal 9200 can be used, for example, as a smartwatch (registered trademark). The display unit 9001 has a curved display surface, allowing it to display information along the curved surface. The personal information terminal 9200 can also be used for hands-free calls by communicating with, for example, a wireless communication headset. Furthermore, the personal information terminal 9200 can transmit data to other information terminals and be charged via a connection terminal 9006. Charging may be performed by wireless power supply.

[0462] Figures 29D to 29F are perspective views showing a foldable personal information terminal 9201. Figure 29D shows the personal information terminal 9201 in an unfolded state, Figure 29F shows it in a folded state, and Figure 29E shows a perspective view of the state in between, transitioning from one of Figures 29D or 29F to the other. The personal information terminal 9201 offers excellent portability in its folded state and excellent readability of the display due to its seamless, wide display area in its unfolded state. The display unit 9001 of the personal information terminal 9201 is supported by three housings 9000 connected by a hinge 9055. For example, the display unit 9001 can be bent with a radius of curvature of 0.1 mm to 150 mm.

[0463] The configuration examples illustrated in this embodiment, and the corresponding drawings, etc., can be appropriately combined with other configuration examples or drawings, etc., at least in part.

[0464] This embodiment can be implemented in appropriate combination with other embodiments described herein, at least in part. [Examples]

[0465] This embodiment shows the results of an investigation into the electrical resistance between conductive layers via the EL layer 114.

[0466] In this embodiment, nine types of samples (samples A1 to A6, and samples B1 to B3) were prepared. Each sample has a light-emitting element and a connecting part.

[0467] The light-emitting elements in each sample were 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] Figure 30 is a cross-sectional view showing the configuration of the connection portion 900 of each sample. The connection portion 900 of each sample has a conductive layer 901 on a glass substrate (not shown), a layer 902 on the conductive layer 901, and a conductive layer 903 on the layer 902. The conductive layer 901 corresponds to the connection electrode 111C described in Embodiment 1, the layer 902 corresponds to the EL layer 114 described in Embodiment 1, and the conductive layer 903 corresponds to the common electrode 113 described in Embodiment 1. In other words, each sample has the configuration of the connection portion 130 described in Embodiment 1.

[0469] The conductive layer 901 was formed using a material that can be used for the connecting electrode 111C. In this example, the conductive layer 901 was a laminated structure consisting 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] 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 layer 902. For samples A1 to A6 and samples B1 to B3, all aspects of layer 902 except for the film thickness (material, deposition conditions, etc.) were the same.

[0471] Each sample had a different thickness of layer 902. Specifically, the thickness of 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. Samples A1 and B1 did not have layer 902 formed.

[0472] The conductive layer 903 was formed using a material that can be used for the common electrode 113. In this embodiment, a laminated structure of a silver-magnesium alloy film and an ITO film on the alloy film was used as the conductive layer 903. 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] Each sample has a different area in the region where conductive layer 901 and conductive layer 903 overlap via layer 902 when viewed from above. Specifically, the area of ​​the region where conductive layer 901 and conductive layer 903 overlap via layer 902 when viewed from above is 10.6 μm × 10.6 μm (= 112.36 μm) for samples A1 to A6. 2 = 0.00011236 mm 2 ) and for samples B1 to B3, 400 μm × 100 μm (= 40000 μm 2 = 0.04 mm 2 In the following, the area of ​​the region where the conductive layer 901 and the conductive layer 903 overlap via layer 902 in a top view may be referred to as the 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 via layer 902 was measured. The light-emitting elements in each sample all exhibited good device characteristics.

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

[0476] Furthermore, the electrical resistance of sample B2 was lower than that of sample A1. Moreover, the electrical resistance of sample B2 and sample B1 were approximately the same. Therefore, it was confirmed that increasing the contact area can reduce the electrical resistance between the connecting electrode 111C and the common electrode 113 via the EL layer 114.

[0477] As shown in Figure 31, it was found that the thinner the film thickness of layer 902, the lower the electrical resistance. Therefore, it was confirmed that the electrical resistance in the thickness direction of the EL layer 114 can be reduced by thinning 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 is 40,000 μm². 2 (0.04mm 2 It was confirmed that even if the value is less than ), it may be possible to reduce the electrical resistance in the thickness direction of the EL layer 114.

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

[0479] For sample C1, the electrical resistance between the conductive layer 901 and the conductive layer 903 via layer 902 was measured. The electrical resistance at the connection portion 900 of sample C1 was 68.5Ω. Furthermore, the light-emitting element of sample C1 showed 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 will be 40,000 μm². 2 (0.04mm 2 It was confirmed that even if the value is less than ), it may be possible to reduce the electrical resistance in the thickness direction of the EL layer 114. [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: Connecting 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: Void, 130: Connection part, 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: Connector, 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: Capacitance, 241: Conductive layer, 242: Connector 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 section, 464: Circuit, 465: Wiring, 466: Conductive layer, 472: FPC, 473: IC, 900: Connection section, 901: Conductive layer, 902: Layer, 903: Conductive layer, 4411: Light-emitting layer, 4412: Light Light layer, 4413: 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 component, 6511: Display panel, 6512: Optical component, 6513: Touch sensor panel, 6515: FPC, 6516: IC, 6517: Printed circuit board, 6518: Battery, 7000: Display unit, 71 00: Television equipment, 7101: Housing, 7103: Stand, 7111: Remote control, 7200: Notebook personal computer, 7211: Housing, 7212: Keyboard, 7213: Pointing device, 7214: External connection port, 7300: Digital signage, 7301: Housing, 7303: Speaker, 7311: Information terminal, 7400: Digital signage, 7401: Pillar, 7411: Information terminal, 8000: Camera, 8001: Housing, 8002: Display unit, 8003: Operation buttons, 8004: Shutter button, 8006: Lens8100: Viewfinder, 8101: Housing, 8102: Display unit, 8103: Button, 8200: Head-mounted display, 8201: Mounting unit, 8202: Lens, 8203: Main unit, 8204: Display unit, 8205: Cable, 8206: Battery, 8300: Head-mounted display, 8301: Housing, 8302: Display unit, 8304: Fixing device, 8305: Lens, 8400: Head-mounted display, 8401: Housing, 8402: Mounting Attachment part, 8403: Cushioning material, 8404: Display unit, 8405: Lens, 9000: Housing, 9001: Display unit, 9003: Speaker, 9005: Operation key, 9006: Connection terminal, 9007: Sensor, 9008: Microphone, 9050: Icon, 9051: Information, 9052: Information, 9053: Information, 9054: Information, 9055: Hinge, 9101: Personal Information Terminal, 9102: Personal Information Terminal, 9200: Personal Information Terminal, 9201: Personal Information Terminal,

Claims

1. It has a light-emitting element and a connecting part, The connection portion is provided along the outer periphery of the display area on which the light-emitting element is provided. The light-emitting element comprises a pixel electrode, an insulating layer on the pixel electrode, a first EL layer on the pixel electrode and on the insulating layer, a second EL layer on the first EL layer, a common electrode on the second EL layer, and a protective layer on the common electrode. The upper surface of the insulating layer has a region having a recess, The protective layer is formed along the recess, The insulating layer has a region that is in contact with the bottom surface of the recess, The connecting portion comprises a connecting electrode, an insulating layer on the connecting electrode, a second EL layer on the connecting electrode and the insulating layer, and a common electrode on the second EL layer. The second EL layer has a third region in contact with the connecting electrode and a second region in contact with the common electrode, through a first opening in the insulating layer. In a top view, the area of ​​the region where the third region and the second region overlap is 40,000 μm² or more. The second EL layer contains lithium fluoride, Display device.

2. In claim 1, The second EL layer has a region with a film thickness of 0.5 nm or more and 1.5 nm or less. Display device.

3. In claim 1 or claim 2, The connecting portion has a comb-like or slit-like upper surface shape. Display device.

Images