Method for manufacturing a display device

Abstract

Provided is a high-definition or high-resolution display device. The display device has a first insulating layer, a second insulating layer, a first conducting layer, a second conducting layer, a first light emitting device, and a second light emitting device. The heights of respective top surfaces of the first insulating layer, the first conducting layer, and the second conducting layer are the same or substantially the same. The first light emitting device has a first pixel electrode on the first conducting layer, a first light emitting layer, and a common electrode. The second light emitting device has a second pixel electrode on the second conducting layer, a second light emitting layer, and a common electrode. The second insulating layer covers the respective side surfaces of the first pixel electrode, the second pixel electrode, the first light emitting layer, and the second light emitting layer.

Description

[Technical Field]

[0001] 1. Field of the Invention One embodiment of the present invention relates to a display device, a display module, and an electronic device. 2. Description of the Related Art One embodiment of the present invention relates to a manufacturing method of a display device.

[0002] One embodiment of the present invention is not limited to the above technical field, and examples of the technical field of one embodiment of the present invention include a semiconductor device, a display device, a light-emitting device, a power storage device, a memory device, an electronic device, a lighting device, an input device (for example, a touch sensor), an input / output device (for example, a touch panel), a driving method thereof, or a manufacturing method thereof. [Background technology]

[0003] In recent years, display devices are expected to be used in a variety of applications. For example, applications of large display devices include home television devices (also called televisions or television receivers), digital signage, and public information displays (PIDs). In addition, development of mobile information terminals such as smartphones and tablet terminals equipped with touch panels is progressing.

[0004] There is also a demand for higher resolution display devices. Devices requiring high resolution display devices, such as those for virtual reality (VR), augmented reality (AR), substitutional reality (SR), and mixed reality (MR), are being actively developed.

[0005] As a display device, for example, a light-emitting device having a light-emitting device (also called a light-emitting element) has been developed. A light-emitting device (also called an EL device or an EL element) utilizing the electroluminescence (hereinafter referred to as EL) phenomenon has features such as being easily thin and lightweight, being capable of high-speed response to input signals, and being capable of being driven by a DC constant voltage power supply, and is therefore applied to a display device.

[0006] Patent Document 1 discloses a display device for VR that uses an organic EL device (also called an organic EL element). [Prior art documents] [Patent documents]

[0007] [Patent Document 1] International Publication No. 2018 / 087625 Summary of the Invention [Problem to be solved by the invention]

[0008] When manufacturing a display device having a plurality of organic EL devices each emitting a different light color, it is necessary to form the light-emitting layers emitting different light colors in the shape of islands.

[0009] For example, island-shaped light-emitting layers can be formed by vacuum deposition using a metal mask (also known as a shadow mask). However, this method can result in deviations in the shape and position of the island-shaped light-emitting layers from the design due to various factors, such as the accuracy of the metal mask, misalignment between the metal mask and the substrate, deflection of the metal mask, and the spread of the contours of the formed film due to vapor scattering, making it difficult to achieve high-definition and high-aperture display devices. Furthermore, during deposition, the contours of the layer can become blurred, resulting in thinning of the edge portions. In other words, the thickness of the island-shaped light-emitting layer can vary depending on the location. Furthermore, when fabricating large, high-resolution, or high-definition display devices, there is a concern that low manufacturing yields may be caused by low dimensional accuracy of the metal mask and deformation due to heat, etc.

[0010] Furthermore, when manufacturing display devices using a vacuum deposition method that uses a metal mask, the metal mask must be cleaned periodically, which stops the process. Therefore, it is desirable to prepare at least two lines of manufacturing equipment, and use one manufacturing equipment while the other is under maintenance. Considering mass production, multiple manufacturing equipment lines are required. Therefore, there is the issue of the extremely large initial investment required to introduce the manufacturing equipment.

[0011] An object of one embodiment of the present invention is to provide a high-resolution display device.An object of one embodiment of the present invention is to provide a high-resolution display device.An object of one embodiment of the present invention is to provide a large-sized display device.An object of one embodiment of the present invention is to provide a small-sized display device.An object of one embodiment of the present invention is to provide a highly reliable display device.

[0012] An object of one embodiment of the present invention is to provide a method for manufacturing a high-resolution display device.An object of one embodiment of the present invention is to provide a method for manufacturing a high-resolution display device.An object of one embodiment of the present invention is to provide a method for manufacturing a large-sized display device.An object of one embodiment of the present invention is to provide a method for manufacturing a small-sized display device.An object of one embodiment of the present invention is to provide a method for manufacturing a highly reliable display device.An object of one embodiment of the present invention is to provide a method for manufacturing a display device with a high yield.

[0013] Note that the description of these problems does not preclude the existence of other problems. One embodiment of the present invention does not necessarily have to solve all of these problems. Problems other than these can be extracted from the description in the specification, drawings, and claims. [Means for solving the problem]

[0014] One embodiment of the present invention is a display device that includes a first insulating layer, a second insulating layer, a first conductive layer, a second conductive layer, a first light-emitting device, and a second light-emitting device, where the first insulating layer, the first conductive layer, and the second conductive layer have the same or approximately the same height as each other at their top surfaces. The first light-emitting device includes a first pixel electrode on the first conductive layer, a first light-emitting layer on the first pixel electrode, and a common electrode on the first light-emitting layer. The second light-emitting device includes a second pixel electrode on the second conductive layer, a second light-emitting layer on the second pixel electrode, and a common electrode on the second light-emitting layer. The second insulating layer covers side surfaces of the first pixel electrode, the second pixel electrode, the first light-emitting layer, and the second light-emitting layer.

[0015] The display device preferably further includes a third insulating layer. The second insulating layer preferably includes an inorganic material. The third insulating layer preferably includes an organic material and overlaps with each of the side surfaces of the first pixel electrode, the second pixel electrode, the first light-emitting layer, and the second light-emitting layer via the second insulating layer.

[0016] The first light-emitting device preferably has a common layer between the first light-emitting layer and the common electrode. The second light-emitting device preferably has a common layer between the second light-emitting layer and the common electrode. The common layer preferably has at least one of a hole injection layer, a hole transport layer, an electron transport layer, and an electron injection layer.

[0017] One embodiment of the present invention includes a first insulating layer, a second insulating layer, a first conductive layer, a second conductive layer, a first light-emitting device, and a second light-emitting device, wherein the first insulating layer, the first conductive layer, and the second conductive layer are aligned or approximately aligned in height at their top surfaces, and the first light-emitting device includes a first pixel electrode on the first conductive layer, a first light-emitting unit on the first pixel electrode, a first charge generation layer on the first light-emitting unit, and a second light-emitting unit on the first charge generation layer. and a common electrode on the second light-emitting unit; the second light-emitting device has a second pixel electrode on the second conductive layer, a third light-emitting unit on the second pixel electrode, a second charge generation layer on the third light-emitting unit, a fourth light-emitting unit on the second charge generation layer, and a common electrode on the fourth light-emitting unit; and a second insulating layer covering each side of the first pixel electrode, the second pixel electrode, the first charge generation layer, and the second charge generation layer.

[0018] The display device preferably further includes a third insulating layer. The second insulating layer preferably includes an inorganic material. The third insulating layer preferably includes an organic material and overlaps with each of the side surfaces of the first pixel electrode, the second pixel electrode, the first charge generation layer, and the second charge generation layer via the second insulating layer.

[0019] The first light-emitting device preferably has a common layer between the second light-emitting unit and the common electrode. The second light-emitting device preferably has a common layer between the fourth light-emitting unit and the common electrode. The common layer preferably has at least one of a hole injection layer, a hole transport layer, an electron transport layer, and an electron injection layer.

[0020] The first light-emitting device and the second light-emitting device preferably emit light of different colors. Alternatively, the display device preferably further includes a first colored layer and a second colored layer that transmit light of different colors. In this case, the first light-emitting device and the second light-emitting device preferably emit white light. Light emitted from the first light-emitting device is preferably extracted to the outside of the display device via the first colored layer. Light emitted from the second light-emitting device is preferably extracted to the outside of the display device via the second colored layer.

[0021] The first insulating layer preferably has a recess, the second insulating layer preferably being located on the recess, and the third insulating layer preferably being located on the second insulating layer.

[0022] One aspect of the present invention is a display module having a display device having any of the above configurations, and including a connector such as a flexible printed circuit (hereinafter referred to as FPC) or a TCP (Tape Carrier Package), or a display module having an integrated circuit (IC) mounted thereon by a COG (Chip On Glass) method or a COF (Chip On Film) method.

[0023] One embodiment of the present invention is an electronic device including the above-described display module and at least one of a housing, a battery, a camera, a speaker, and a microphone.

[0024] One embodiment of the present invention includes forming a conductive film on an insulating surface, forming a first layer on the conductive film, forming a first sacrificial layer on the first layer, processing the first layer and the first sacrificial layer to expose a part of the conductive film, forming a second layer on the first sacrificial layer and the conductive film, forming a second sacrificial layer on the second layer, processing the second layer and the second sacrificial layer to expose a part of the conductive film, and processing the conductive film to form a first pixel electrode overlapping with the first sacrificial layer and a second pixel electrode overlapping with the second sacrificial layer, The method for manufacturing a display device also includes forming a first insulating film that covers side surfaces of the first pixel electrode, side surfaces of the second pixel electrode, side surfaces of the first layer, side surfaces of the second layer, side surfaces and a top surface of the first sacrificial layer, and side surfaces and a top surface of the second sacrificial layer, processing the first insulating film to form a first insulating layer that covers at least side surfaces of the first pixel electrode, side surfaces of the second pixel electrode, side surfaces of the first layer, and side surfaces of the second layer, removing the first sacrificial layer and the second sacrificial layer, and forming a common electrode on the first layer and the second layer.

[0025] Alternatively, one embodiment of the present invention includes forming a conductive film over an insulating surface, forming a first layer over the conductive film, forming a first sacrificial layer over the first layer, processing the first layer and the first sacrificial layer to expose part of the conductive film, forming a second layer over the first sacrificial layer and the conductive film, forming a second sacrificial layer over the second layer, processing the second layer and the second sacrificial layer to expose part of the conductive film, and processing the conductive film to form a first pixel electrode overlapping with the first sacrificial layer and a second pixel electrode overlapping with the second sacrificial layer; and forming a conductive film on at least a side surface of the first pixel electrode and a side surface of the second pixel electrode using an inorganic material. a first insulating film covering a top surface, side surfaces of the first layer, side surfaces of the second layer, side surfaces and top surface of the first sacrificial layer, and side surfaces and top surface of the second sacrificial layer; forming a second insulating film on the first insulating film using an organic material; processing the first insulating film and the second insulating film to form a first insulating layer and a second insulating layer on the first insulating layer that cover at least the side surfaces of the first pixel electrode, the side surfaces of the second pixel electrode, the side surfaces of the first layer, and the side surfaces of the second layer; removing the first sacrificial layer and the second sacrificial layer; and forming a common electrode on the first layer and the second layer.

[0026] By processing the conductive film, a first conductive layer that overlaps with at least one of the first sacrificial layer and the second sacrificial layer is formed, a second insulating film is formed so as to have an opening at a position that overlaps with the first conductive layer, and a common electrode is formed on the first conductive layer.

[0027] The second insulating film may be formed using a photosensitive resin as the organic material.

[0028] After forming the common electrode, at least a portion of the area of ​​the common electrode outside the area overlapping with the first conductive layer may be removed.

[0029] As the first sacrificial layer, a first sacrificial film and a second sacrificial film on the first sacrificial film may be formed, a first resist mask may be formed on the second sacrificial film, the second sacrificial film may be processed using the first resist mask, the first resist mask may be removed, the processed second sacrificial film may be used as a hard mask to process the first sacrificial film, and the processed first sacrificial film may be used as a hard mask to process the first layer.

[0030] The conductive film may be processed using the first sacrificial layer and the second sacrificial layer as a hard mask.

[0031] After removing the first sacrificial layer and the second sacrificial layer, a third layer may be formed on the first layer and the second layer, and a common electrode may be formed on the third layer.

[0032] In the process of processing the conductive film, recesses may be formed in the insulating surface.

[0033] The conductive film may be a first conductive film having a recess and a second conductive film on the first conductive film, a fourth layer may be formed in the recess of the first conductive film, and then the second conductive film may be formed on the first conductive film and the fourth layer. The fourth layer may be formed using an organic material. [Effects of the Invention]

[0034] According to one embodiment of the present invention, a high-definition display device can be provided. According to one embodiment of the present invention, a high-resolution display device can be provided. According to one embodiment of the present invention, a large-sized display device can be provided. According to one embodiment of the present invention, a small-sized display device can be provided. According to one embodiment of the present invention, a highly reliable display device can be provided.

[0035] According to one embodiment of the present invention, a method for manufacturing a high-resolution display device can be provided. According to one embodiment of the present invention, a method for manufacturing a high-resolution display device can be provided. According to one embodiment of the present invention, a method for manufacturing a large-sized display device can be provided. According to one embodiment of the present invention, a method for manufacturing a small-sized display device can be provided. According to one embodiment of the present invention, a method for manufacturing a highly reliable display device can be provided. According to one embodiment of the present invention, a method for manufacturing a display device with a high yield can be provided.

[0036] Note that the description of these effects does not preclude the existence of other effects. One embodiment of the present invention does not necessarily have all of these effects. Effects other than these can be extracted from the description in the specification, drawings, and claims. [Brief explanation of the drawings]

[0037] 1A and 1B are a top view and a cross-sectional view, respectively, illustrating an example of a display device. 2A and 2B are a top view and a cross-sectional view illustrating an example of a display device. 3A to 3E are top views showing an example of a pixel. 4A to 4E are top views showing an example of a pixel. 5A to 5G are top views showing an example of a pixel. 6A to 6D are top views showing an example of a pixel. 7A to 7C are schematic diagrams showing an example of an electronic device. 8A to 8D are top views showing an example of a pixel, and Fig. 8E to Fig. 8G are cross-sectional views showing an example of a display device. 9A to 9E are top views illustrating an example of a method for manufacturing a display device. 10A to 10C are cross-sectional views showing an example of a method for manufacturing a display device. 11A to 11C are cross-sectional views showing an example of a method for manufacturing a display device. 12A to 12C are cross-sectional views showing an example of a method for manufacturing a display device. 13A to 13C are cross-sectional views showing an example of a method for manufacturing a display device. 14A to 14C are cross-sectional views showing an example of a method for manufacturing a display device. 15A and 15B are cross-sectional views showing an example of a method for manufacturing a display device. 16A to 16E are cross-sectional views showing an example of a method for manufacturing a display device. 17A to 17F are cross-sectional views showing an example of a method for manufacturing a display device. 18A to 18C are cross-sectional views showing an example of a display device. 19A and 19B are cross-sectional views showing an example of a display device. 20A and 20B are cross-sectional views showing an example of a display device. 21A and 21B are cross-sectional views showing an example of a display device. 22A and 22B are cross-sectional views showing an example of a display device. FIG. 23 is a perspective view showing an example of a display device. 24A is a cross-sectional view showing an example of a display device, and FIGS. 24B and 24C are cross-sectional views showing an example of a transistor. FIG. 25 is a cross-sectional view showing an example of a display device. 26A and 26B are perspective views showing an example of a display module. FIG. 27 is a cross-sectional view showing an example of a display device. FIG. 28 is a cross-sectional view showing an example of a display device. FIG. 29 is a cross-sectional view showing an example of a display device. Fig. 30A is a block diagram showing an example of a display device, and Fig. 30B to Fig. 30D are diagrams showing an example of a pixel circuit. 31A to 31D are diagrams showing an example of a transistor. 32A and 32B are diagrams showing an example of an electronic device. 33A and 33B are diagrams showing an example of an electronic device. 34A and 34B are diagrams showing an example of an electronic device. 35A to 35D are diagrams showing an example of an electronic device. 36A to 36G are diagrams showing an example of an electronic device. DETAILED DESCRIPTION OF THE INVENTION

[0038] The embodiments will be described in detail with reference to the drawings. However, the present invention is not limited to the following description, and it will be readily understood by those skilled in the art that various changes can be made in form and detail without departing from the spirit and scope of the present invention. Therefore, the present invention should not be interpreted as being limited to the description of the embodiments shown below.

[0039] In the configuration of the invention described below, the same parts or parts having similar functions are denoted by the same reference numerals in different drawings, and repeated explanations thereof will be omitted. Furthermore, when referring to similar functions, the same hatching pattern may be used and no particular reference numeral may be assigned.

[0040] Furthermore, for ease of understanding, the position, size, range, etc. of each component shown in the drawings may not represent the actual position, size, range, etc. Therefore, the disclosed invention is not necessarily limited to the position, size, range, etc. disclosed in the drawings.

[0041] It should be noted that the terms "film" and "layer" can be interchangeable depending on the circumstances. For example, the term "conductive layer" can be changed to the term "conductive film." Or, for example, the term "insulating film" can be changed to the term "insulating layer."

[0042] (Embodiment 1) In this embodiment, a display device of one embodiment of the present invention and a manufacturing method thereof will be described with reference to FIGS.

[0043] In a manufacturing method of a display device according to one embodiment of the present invention, a conductive film is formed, and a first layer (which can be referred to as an EL layer or a part of an EL layer) including a light-emitting layer emitting light of a first color is formed over the entire surface. Then, a first sacrificial layer is formed over the first layer. Then, a first resist mask is formed over the first sacrificial layer, and the first layer and the first sacrificial layer are processed using the first resist mask to form an island-shaped first layer. Subsequently, a second layer (which can be referred to as an EL layer or a part of an EL layer) including a light-emitting layer emitting light of a second color is formed in an island shape using a second sacrificial layer and a second resist mask, similar to the first layer.

[0044] As described above, in the manufacturing method of a display device according to one embodiment of the present invention, the island-shaped EL layer is formed by forming the EL layer over the entire surface and then processing it, rather than using a metal mask having a fine pattern. Therefore, it is possible to realize a high-definition display device or a display device with a high aperture ratio, which has been difficult to achieve until now. Furthermore, since the EL layer can be formed separately for each color, it is possible to realize a display device that is extremely vivid, has high contrast, and has high display quality. Furthermore, by providing a sacrificial layer (which may also be referred to as a mask layer) on the EL layer, damage to the EL layer during the manufacturing process of the display device can be reduced, thereby improving the reliability of the light-emitting device.

[0045] While it is difficult to achieve a spacing of less than 10 μm between adjacent light-emitting devices using, for example, a metal mask, the above-described method allows for a spacing of less than 10 μm, 5 μm or less, 3 μm or less, 2 μm or less, or even 1 μm or less. Furthermore, by using an exposure device for LSIs, for example, it is possible to narrow the spacing to 500 nm or less, 200 nm or less, 100 nm or less, or even 50 nm or less. This significantly reduces the area of ​​the non-light-emitting region that may exist between two light-emitting devices, enabling an aperture ratio approaching 100%. For example, an aperture ratio of 50% or more, 60% or more, 70% or more, 80% or more, or even 90% or more, but less than 100%, can be achieved.

[0046] Furthermore, the pattern of the EL layer itself (also known as the processing size) can be made much smaller than when a metal mask is used. Furthermore, for example, when a metal mask is used to separately fabricate an EL layer, thickness variations occur between the center and edges of the EL layer, resulting in a smaller effective area that can be used as a light-emitting region relative to the area of ​​the EL layer. On the other hand, with the above-described fabrication method, a film formed to a uniform thickness is processed, so island-shaped EL layers can be formed with a uniform thickness. Therefore, even with a fine pattern, almost the entire area can be used as a light-emitting region. This makes it possible to fabricate a display device that combines high definition and a high aperture ratio.

[0047] After forming the EL layers that emit light of each color, the sacrificial layer remaining on each EL layer can be used as a hard mask to process the conductive film to form pixel electrodes. Since there is no need to provide a separate mask for forming the pixel electrodes in an island shape, the manufacturing cost of the display device can be reduced. Furthermore, since there is no need to provide an insulating layer between the pixel electrodes and the EL layer to cover the edges of the pixel electrodes, the distance between adjacent light-emitting devices can be made extremely narrow. This allows for higher definition or higher resolution of the display device. Furthermore, there is no need for a mask for forming the insulating layer, which reduces the manufacturing cost of the display device.

[0048] Here, the first layer and the second layer each include at least a light-emitting layer and preferably consist of multiple layers. Specifically, it is preferable to have one or more layers on the light-emitting layer. By having another layer between the light-emitting layer and the sacrificial layer, it is possible to prevent the light-emitting layer from being exposed to the outermost surface during the manufacturing process of the display device, thereby reducing damage to the light-emitting layer. This can improve the reliability of the light-emitting device. Therefore, it is preferable that the first layer and the second layer each have a light-emitting layer and a carrier transport layer (electron transport layer or hole transport layer) on the light-emitting layer.

[0049] In light-emitting devices emitting light of different colors, it is not necessary to separately fabricate all layers constituting the EL layer; some layers can be formed in the same process. In a method for fabricating a display device according to one embodiment of the present invention, some layers constituting the EL layer are formed in an island shape for each color, and then the sacrificial layer is removed. The remaining layers constituting the EL layer and a common electrode (also referred to as an upper electrode) are formed (as a single film) in common to the light-emitting devices of each color. For example, a carrier injection layer and a common electrode can be formed in common to the light-emitting devices of each color. Meanwhile, the carrier injection layer is often a relatively highly conductive layer among the EL layers. Therefore, contact between the carrier injection layer and the side surface of a part of the island-shaped EL layer or the side surface of the pixel electrode may cause a short circuit in the light-emitting device. Even when the carrier injection layer is formed in an island shape and a common electrode is formed in common to the light-emitting devices of each color, contact between the common electrode and the side surface of the EL layer or the side surface of the pixel electrode may cause a short circuit in the light-emitting device.

[0050] Therefore, a display device according to one embodiment of the present invention includes an insulating layer that covers the side surfaces of the island-shaped light-emitting layer and the side surfaces of the pixel electrode.

[0051] This prevents at least a portion of the island-shaped EL layer and the pixel electrode from coming into contact with the carrier injection layer or the common electrode, thereby preventing short circuits in the light-emitting device and improving the reliability of the light-emitting device.

[0052] A display device of one embodiment of the present invention includes a pixel electrode that functions as an anode; a hole-injection layer, a hole-transport layer, a light-emitting layer, and an electron-transport layer that are each provided in this order over the pixel electrode, and each have an island shape; insulating layers that are provided so as to cover side surfaces of the pixel electrode, the hole-injection layer, the hole-transport layer, the light-emitting layer, and the electron-transport layer; an electron-injection layer that is provided over the electron-transport layer; and a common electrode that is provided over the electron-injection layer and functions as a cathode.

[0053] Alternatively, a display device of one embodiment of the present invention includes a pixel electrode that functions as a cathode; an electron-injection layer, an electron-transport layer, a light-emitting layer, and a hole-transport layer that are provided in this order over the pixel electrode, each of which has an island shape; insulating layers that are provided so as to cover side surfaces of the pixel electrode, the electron-injection layer, the electron-transport layer, the light-emitting layer, and the hole-transport layer; a hole-injection layer that is provided over the hole-transport layer; and a common electrode that is provided over the hole-injection layer and functions as an anode.

[0054] Alternatively, a display device according to one embodiment of the present invention includes a pixel electrode, a first light-emitting unit on the pixel electrode, a charge generation layer (also referred to as an intermediate layer) on the first light-emitting unit, a second light-emitting unit on the charge generation layer, an insulating layer provided so as to cover each side surface of the pixel electrode, the first light-emitting unit, the charge generation layer, and the second light-emitting unit, and a common electrode provided on the second light-emitting unit. Note that a common layer may be provided between the second light-emitting unit and the common electrode for light-emitting devices of each color.

[0055] Among EL layers, the hole injection layer, the electron injection layer, the charge generation layer, and the like are often layers with relatively high conductivity. In the display device of one embodiment of the present invention, the side surfaces of these layers are covered with an insulating layer, which can prevent them from contacting a common electrode or the like. Therefore, short circuits in the light-emitting device can be prevented, and the reliability of the light-emitting device can be improved.

[0056] This configuration allows the fabrication of a highly reliable display device with high definition or resolution. For example, even with an arrangement method using three or more sub-pixels per pixel, an extremely high-definition display device can be realized without the need to artificially increase the definition by applying a special pixel arrangement method such as a pen-tile method. For example, a display device with a so-called stripe arrangement in which R, G, and B are each arranged in one direction can be realized, and with a resolution of 500 ppi or more, 1000 ppi or more, 2000 ppi or more, or even 3000 ppi or more, or even 5000 ppi or more.

[0057] The insulating layer may have a single-layer structure or a laminated structure. It is particularly preferable to use an insulating layer with a two-layer structure. For example, since the first insulating layer is formed in contact with the EL layer, it is preferably formed using an inorganic insulating material. It is particularly preferable to form it using atomic layer deposition (ALD), which causes less film damage. It is also preferable to form the inorganic insulating layer using sputtering, chemical vapor deposition (CVD), or plasma enhanced CVD (PECVD), which have faster film formation rates than ALD. This allows for the production of highly reliable display devices with high productivity. It is also preferable to form the second insulating layer using an organic material so as to flatten recesses formed in the first insulating layer.

[0058] For example, an aluminum oxide film formed by ALD can be used as the first insulating layer, and a photosensitive organic resin film can be used as the second insulating layer.

[0059] Alternatively, an insulating layer having a single layer structure may be formed. For example, by forming an insulating layer having a single layer structure using an inorganic material, the insulating layer can be used as a protective insulating layer for the EL layer. This can improve the reliability of the display device. Furthermore, by forming an insulating layer having a single layer structure using an organic material, the insulating layer can fill the gap between adjacent EL layers and achieve planarization. This can improve the coverage of the common electrode (upper electrode) formed on the EL layer and the insulating layer.

[0060] [Display device configuration example 1] 1A and 1B show a display device according to one embodiment of the present invention.

[0061] 1A shows a top view of a display device 100. The display device 100 has a display section in which a plurality of pixels 110 are arranged in a matrix, and a connection section 140 outside the display section. The connection section 140 can also be called a cathode contact section.

[0062] A stripe arrangement is applied to the pixel 110 shown in Fig. 1A. The pixel 110 shown in Fig. 1A is composed of three subpixels, 110a, 110b, and 110c. The subpixels 110a, 110b, and 110c each have a light-emitting device that emits light of a different color. Examples of the subpixels 110a, 110b, and 110c include three subpixels of red (R), green (G), and blue (B), and three subpixels of yellow (Y), cyan (C), and magenta (M).

[0063] The top surface shape of the sub-pixel shown in FIG. 1A corresponds to the top surface shape of the light-emitting region.

[0064] Furthermore, the circuit layout constituting the subpixels is not limited to the range of the subpixels shown in Fig. 1A and may be located outside of it. For example, some or all of the transistors included in the subpixel 110a may be located outside the range of the subpixel 110a shown in Fig. 1A. For example, the transistor included in the subpixel 110a may have a portion located within the range of the subpixel 110b and a portion located within the range of the subpixel 110c.

[0065] 1A shows the subpixels 110a, 110b, and 110c as having the same or approximately the same aperture ratio (size, or the size of the light-emitting region), but this is not a limitation of the present invention. The aperture ratios of the subpixels 110a, 110b, and 110c can be determined as appropriate. The aperture ratios of the subpixels 110a, 110b, and 110c may be different from one another, or two or more of the subpixels may have the same or approximately the same aperture ratio.

[0066] 1A shows an example in which subpixels of different colors are arranged side by side in the X direction, and subpixels of the same color are arranged side by side in the Y direction. Note that subpixels of different colors may also be arranged side by side in the Y direction, and subpixels of the same color may also be arranged side by side in the X direction.

[0067] 1A shows an example in which the connection unit 140 is located below the display unit when viewed from above, but this is not particularly limited. The connection unit 140 only needs to be located in at least one of the upper, right, left, and lower sides of the display unit when viewed from above, and may be located so as to surround all four sides of the display unit. Furthermore, the connection unit 140 may be singular or plural.

[0068] FIG. 1B shows a cross-sectional view taken along the dashed line X1-X2 in FIG. 1A.

[0069] 1B, display device 100 has light-emitting devices 130a, 130b, and 130c provided on transistor-containing layer 101, and protective layers 131 and 132 provided to cover these light-emitting devices. Substrate 120 is bonded to protective layer 132 with resin layer 122. In addition, insulating layer 125 and insulating layer 127 on insulating layer 125 are provided in the regions between adjacent light-emitting devices.

[0070] The display device of one embodiment of the present invention may be any of a top-emission type that emits light in a direction opposite to a substrate on which a light-emitting device is formed, a bottom-emission type that emits light toward a substrate on which a light-emitting device is formed, and a dual-emission type that emits light from both sides.

[0071] The transistor-containing layer 101 may have a laminated structure in which, for example, a plurality of transistors are provided on a substrate and an insulating layer is provided to cover these transistors. The transistor-containing layer 101 may have a recess between adjacent light-emitting devices. For example, a recess may be provided in an insulating layer located on the outermost surface of the transistor-containing layer 101. Configuration examples of the transistor-containing layer 101 will be described later in Embodiments 3 and 4.

[0072] The light emitting devices 130a, 130b, and 130c each emit light of a different color, and preferably emit light of three colors, for example, red (R), green (G), and blue (B).

[0073] The light-emitting devices 130a, 130b, and 130c preferably include, for example, organic light-emitting diodes (OLEDs) or quantum-dot light-emitting diodes (QLEDs). Examples of light-emitting materials included in the light-emitting devices include fluorescent materials, phosphorescent materials, and thermally activated delayed fluorescence (TADF) materials. The TADF material may be a material that is in thermal equilibrium between a singlet excited state and a triplet excited state. Such TADF materials have a short emission lifetime (excitation lifetime), which can suppress a decrease in efficiency in the high-brightness region of the light-emitting device. Alternatively, the light-emitting device may include an inorganic compound (such as a quantum dot material) as the light-emitting material.

[0074] A light-emitting device has an EL layer between a pair of electrodes. In this specification and the like, one of the pair of electrodes may be referred to as a pixel electrode and the other as a common electrode.

[0075] A light-emitting device has a pair of electrodes, one of which functions as an anode and the other as a cathode. In the following, an example will be described in which the pixel electrode functions as the anode and the common electrode functions as the cathode.

[0076] The light-emitting device 130a includes a pixel electrode 111a on the transistor-containing layer 101, an island-shaped first layer 113a on the pixel electrode 111a, a fifth layer 114 on the island-shaped first layer 113a, and a common electrode 115 on the fifth layer 114. In the light-emitting device 130a, the first layer 113a and the fifth layer 114 can be collectively referred to as an EL layer.

[0077] The structure of the light emitting device of this embodiment is not particularly limited, and may be a single structure or a tandem structure. An example of the structure of the light emitting device will be described later in the second embodiment.

[0078] Light-emitting device 130b has a pixel electrode 111b on the transistor-containing layer 101, an island-shaped second layer 113b on pixel electrode 111b, a fifth layer 114 on the island-shaped second layer 113b, and a common electrode 115 on the fifth layer 114. In light-emitting device 130b, second layer 113b and fifth layer 114 can be collectively referred to as an EL layer.

[0079] The light-emitting device 130c includes a pixel electrode 111c on the transistor-containing layer 101, an island-shaped third layer 113c on the pixel electrode 111c, a fifth layer 114 on the island-shaped third layer 113c, and a common electrode 115 on the fifth layer 114. In the light-emitting device 130c, the third layer 113c and the fifth layer 114 can be collectively referred to as an EL layer.

[0080] The light emitting devices of each color share the same film as a common electrode. The common electrode shared by the light emitting devices of each color is electrically connected to a conductive layer provided in the connection section 140.

[0081] Of the pixel electrode and the common electrode, the electrode from which light is extracted is preferably made of a conductive film that transmits visible light, and the electrode from which light is not extracted is preferably made of a conductive film that reflects visible light.

[0082] The pair of electrodes (pixel electrode and common electrode) of the light-emitting device can be formed from a metal, an alloy, an electrically conductive compound, a mixture thereof, etc. Specific examples include indium tin oxide (In-Sn oxide, also referred to as ITO), In-Si-Sn oxide (also referred to as ITSO), indium zinc oxide (In-Zn oxide), In-W-Zn oxide, an aluminum alloy (aluminum alloy) such as an alloy of aluminum, nickel, and lanthanum (Al-Ni-La), and a silver alloy such as an alloy of silver and magnesium and an alloy of silver, palladium, and copper (Ag-Pd-Cu, also referred to as APC). Other examples of usable materials include aluminum (Al), magnesium (Mg), titanium (Ti), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), gallium (Ga), zinc (Zn), indium (In), tin (Sn), molybdenum (Mo), tantalum (Ta), tungsten (W), palladium (Pd), gold (Au), platinum (Pt), silver (Ag), yttrium (Y), and neodymium (Nd), as well as alloys containing these metals in combination. Other examples include rare earth metals such as lithium (Li), cesium (Cs), calcium (Ca), and strontium (Sr), europium (Eu), and ytterbium (Yb), as well as alloys containing these metals in combination. Graphene and other materials can also be used.

[0083] A light-emitting device preferably has a micro-optical resonator (microcavity) structure. Therefore, one of a pair of electrodes of the light-emitting device preferably has a transmissive and reflective electrode for visible light, and the other preferably has a reflective electrode for visible light. By having a microcavity structure in the light-emitting device, the light emitted from the light-emitting layer can be resonated between the two electrodes, thereby intensifying the light emitted from the light-emitting device.

[0084] The semi-transmitting / semi-reflective electrode can have a laminated structure of a reflective electrode and an electrode that is transparent to visible light (also called a transparent electrode).

[0085] The light transmittance of the transparent electrode is 40% or more. For example, it is preferable to use an electrode with a visible light (light with a wavelength of 400 nm or more and less than 750 nm) transmittance of 40% or more for a light-emitting device. The visible light reflectance of the semi-transparent / semi-reflective electrode is 10% or more and 95% or less, preferably 30% or more and 80% or less. The visible light reflectance of the reflective electrode is 40% or more and 100% or less, preferably 70% or more and 100% or less. The resistivity of these electrodes is 1×10 -2 Ωcm or less is preferable.

[0086] The first layer 113a, the second layer 113b, and the third layer 113c are each provided in an island shape. The first layer 113a, the second layer 113b, and the third layer 113c each have a light-emitting layer. It is preferable that the first layer 113a, the second layer 113b, and the third layer 113c each have a light-emitting layer that emits light of a different color.

[0087] The light-emitting layer is a layer containing a light-emitting substance. The light-emitting layer can contain one or more light-emitting substances. As the light-emitting substance, a substance that emits light of a color such as blue, purple, blue-purple, green, yellow-green, yellow, orange, or red is appropriately used. Furthermore, a substance that emits near-infrared light can also be used as the light-emitting substance.

[0088] Examples of light-emitting materials include fluorescent materials, phosphorescent materials, TADF materials, and quantum dot materials.

[0089] 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.

[0090] Examples of phosphorescent materials include organometallic complexes (particularly iridium complexes) having a 4H-triazole skeleton, a 1H-triazole skeleton, an imidazole skeleton, a pyrimidine skeleton, a pyrazine skeleton, or a pyridine skeleton; organometallic complexes (particularly iridium complexes) having a phenylpyridine derivative having an electron-withdrawing group as a ligand; platinum complexes; and rare earth metal complexes.

[0091] The light-emitting layer may contain one or more organic compounds (host materials, assist materials, etc.) in addition to a light-emitting substance (guest material). One or more organic compounds may be a hole-transporting material or an electron-transporting material, or both. Alternatively, a bipolar material or a TADF material may be used as the one or more organic compounds.

[0092] The light-emitting layer preferably contains, for example, a phosphorescent material and a hole-transporting material and an electron-transporting material that are a combination that easily forms an exciplex. This configuration allows for efficient emission using Exciplex-Triplet Energy Transfer (ExTET), which is energy transfer from the exciplex to the light-emitting material (phosphorescent material). By selecting a combination that forms an exciplex that emits light that overlaps with the wavelength of the lowest-energy absorption band of the light-emitting material, the energy transfer becomes smooth, allowing for efficient emission. This configuration simultaneously enables high efficiency, low-voltage operation, and long life of the light-emitting device.

[0093] The first layer 113a, the second layer 113b, and the third layer 113c may further include, as a layer other than the light-emitting layer, a layer containing a substance with a high hole-injection property, a substance with a high hole-transport property (also referred to as a hole-transport material), a hole-blocking material, a substance with a high electron-transport property (also referred to as an electron-transport material), a substance with a high electron-injection property, an electron-blocking material, a bipolar substance (a substance with high electron-transport property and high hole-transport property, also referred to as a bipolar material), or the like.

[0094] For example, the first layer 113a, the second layer 113b, and the third layer 113c may each include one or more of a hole injection layer, a hole transport layer, a hole blocking layer, an electron blocking layer, an electron transport layer, and an electron injection layer.

[0095] The EL layer may include one or more of a hole injection layer, a hole transport layer, a hole blocking layer, an electron blocking layer, an electron transport layer, and an electron injection layer, as layers commonly formed in the light-emitting devices of each color. For example, a carrier injection layer (hole injection layer or electron injection layer) may be formed as the fifth layer 114. All layers in the EL layer may be formed separately for each color. In other words, the EL layer does not need to include a layer commonly formed in the light-emitting devices of each color.

[0096] Each of the first layer 113a, the second layer 113b, and the third layer 113c preferably includes a light-emitting layer and a carrier transport layer on the light-emitting layer. This prevents the light-emitting layer from being exposed to the outermost surface during the manufacturing process of the display device 100, thereby reducing damage to the light-emitting layer. This improves the reliability of the light-emitting device.

[0097] The hole injection layer is a layer that injects holes from the anode into the hole transport layer and contains a substance with high hole injection properties, such as an aromatic amine compound and a composite material containing a hole transport material and an acceptor material (electron acceptor material).

[0098] The hole transport layer is a layer that transports holes injected from the anode by the hole injection layer to the light emitting layer. The hole transport layer is a layer that contains a hole transport material. The hole transport material is a material having a concentration of 1×10 -6 cm 2 A substance having a hole mobility of 1 / Vs or more is preferred. Note that other substances can also be used as long as they have a higher hole transporting property than electron transporting property. As the hole transporting material, a substance having a high hole transporting property, such as a π-electron-rich heteroaromatic compound (e.g., a carbazole derivative, a thiophene derivative, a furan derivative, etc.) or an aromatic amine (a compound having an aromatic amine skeleton), is preferred.

[0099] The electron transport layer is a layer that transports electrons injected from the cathode by the electron injection layer to the light emitting layer. The electron transport layer is a layer that contains an electron transporting material. The electron transporting material is a material having a concentration of 1×10 -6 cm 2 A substance having an electron mobility of 1 / Vs or more is preferred. Note that other substances can also be used as long as they have a higher electron transporting property than holes. Examples of electron-transporting materials that can be used include metal complexes having a quinoline skeleton, metal complexes having a benzoquinoline skeleton, metal complexes having an oxazole skeleton, and metal complexes having a thiazole skeleton, as well as oxadiazole derivatives, triazole derivatives, imidazole derivatives, oxazole derivatives, thiazole derivatives, phenanthroline derivatives, quinoline derivatives having a quinoline ligand, benzoquinoline derivatives, quinoxaline derivatives, dibenzoquinoxaline derivatives, pyridine derivatives, bipyridine derivatives, pyrimidine derivatives, and other π-electron-deficient heteroaromatic compounds including nitrogen-containing heteroaromatic compounds.

[0100] The electron injection layer is a layer that injects electrons from the cathode to the electron transport layer and contains a substance with high electron injection properties. Examples of the substance with high electron injection properties include alkali metals, alkaline earth metals, and compounds thereof. Examples of the substance with high electron injection properties include a composite material containing an electron transport material and a donor material (electron donor material).

[0101] The electron injection layer may be formed of, for example, lithium, cesium, ytterbium, lithium fluoride (LiF), cesium fluoride (CsF), calcium fluoride (CaF x , where X is an arbitrary number), 8-(quinolinolato)lithium (abbreviation: Liq), 2-(2-pyridyl)phenolatolithium (abbreviation: LiPP), 2-(2-pyridyl)-3-pyridinolatolithium (abbreviation: LiPPy), 4-phenyl-2-(2-pyridyl)phenolatolithium (abbreviation: LiPPP), lithium oxide (LiO x The electron injection layer may be formed of an alkali metal, an alkaline earth metal, such as cesium carbonate, or a compound thereof. The electron injection layer may have a stacked structure of two or more layers. For example, the stacked structure may have a structure in which lithium fluoride is used in the first layer and ytterbium is provided in the second layer.

[0102] Alternatively, an electron transporting material may be used for the electron injection layer. For example, a compound having an unshared electron pair and an electron-deficient heteroaromatic ring may be used as the electron transporting material. Specifically, a compound having at least one of a pyridine ring, a diazine ring (pyrimidine ring, pyrazine ring, pyridazine ring), and a triazine ring may be used.

[0103] The organic compound having an unshared electron pair preferably has a lowest unoccupied molecular orbital (LUMO) of -3.6 eV to -2.3 eV. Generally, the highest occupied molecular orbital (HOMO) level and the LUMO level of an organic compound can be estimated by cyclic voltammetry (CV), photoelectron spectroscopy, optical absorption spectroscopy, inverse photoelectron spectroscopy, or the like.

[0104] Examples of organic compounds with lone electron pairs include 4,7-diphenyl-1,10-phenanthroline (abbreviated as BPhen), 2,9-bis(naphthalen-2-yl)-4,7-diphenyl-1,10-phenanthroline (abbreviated as NBPhen), diquinoxalino[2,3-a:2',3'-c]phenazine (abbreviated as HATNA), and 2,4,6-tris[3'-(pyridin-3-yl)biphenyl-3-yl]-1,3,5-triazine (abbreviated as TmPPPyTz). NBPhen has a higher glass transition temperature (Tg) and better heat resistance than BPhen.

[0105] When fabricating a light-emitting device with a tandem structure, a charge-generating layer is provided between the two light-emitting units. The charge-generating layer has at least a charge-generating region. When a voltage is applied between a pair of electrodes, the charge-generating layer injects electrons into one of the two light-emitting units and holes into the other.

[0106] As described above, the charge generation layer has at least a charge generation region. The charge generation region preferably contains an acceptor material, for example, a hole transport material and an acceptor material applicable to the hole injection layer.

[0107] The charge generation layer preferably includes a layer containing a substance with high electron injection properties. This layer may also be called an electron injection buffer layer. The electron injection buffer layer is preferably provided between the charge generation region and the electron transport layer. By providing the electron injection buffer layer, the injection barrier between the charge generation region and the electron transport layer can be alleviated, so that electrons generated in the charge generation region can be easily injected into the electron transport layer.

[0108] The electron injection buffer layer preferably contains an alkali metal or an alkaline earth metal, and may contain, for example, an alkali metal compound or an alkaline earth metal compound. Specifically, the electron injection buffer layer preferably contains an inorganic compound containing an alkali metal and oxygen, or an inorganic compound containing an alkaline earth metal and oxygen, and more preferably contains an inorganic compound containing lithium and oxygen (such as lithium oxide (LiO)). In addition, the electron injection buffer layer can suitably use the materials applicable to the electron injection layer described above.

[0109] The charge generation layer preferably has a layer containing a substance with high electron transport properties. This layer can also be called an electron relay layer. The electron relay layer is preferably provided between the charge generation region and the electron injection buffer layer. When the charge generation layer does not have an electron injection buffer layer, the electron relay layer is preferably provided between the charge generation region and the electron transport layer. The electron relay layer has the function of preventing interaction between the charge generation region and the electron injection buffer layer (or the electron transport layer) and smoothly transferring electrons.

[0110] As the electron relay layer, it is preferable to use a phthalocyanine material such as copper (II) phthalocyanine (abbreviated as CuPc) or a metal complex having a metal-oxygen bond and an aromatic ligand.

[0111] It should be noted that the charge generation region, electron injection buffer layer, and electron relay layer may not be clearly distinguishable from one another depending on their cross-sectional shapes or characteristics.

[0112] The charge generation layer may contain a donor material instead of an acceptor material. For example, the charge generation layer may contain a layer containing an electron transport material and a donor material that can be used for the electron injection layer.

[0113] When stacking light-emitting units, an increase in driving voltage can be suppressed by providing a charge-generating layer between two light-emitting units.

[0114] The light-emitting device can be made of either a low-molecular-weight compound or a high-molecular-weight compound, and may contain an inorganic compound. The layers constituting the light-emitting device can be formed by a method such as vapor deposition (including vacuum vapor deposition), transfer, printing, inkjet printing, or coating.

[0115] The side surfaces of the pixel electrodes 111a, 111b, and 111c, the first layer 113a, the second layer 113b, and the third layer 113c are covered with the insulating layer 125 and the insulating layer 127. This prevents the fifth layer 114 (or the common electrode 115) from coming into contact with any of the side surfaces of the pixel electrodes 111a, 111b, and 111c, the first layer 113a, the second layer 113b, and the third layer 113c, thereby preventing short circuits in the light-emitting device.

[0116] The insulating layer 125 preferably covers at least the side surfaces of the pixel electrodes 111a, 111b, and 111c. Furthermore, the insulating layer 125 preferably covers the side surfaces of the first layer 113a, the second layer 113b, and the third layer 113c. The insulating layer 125 can be configured to be in contact with the side surfaces of each of the pixel electrodes 111a, 111b, and 111c, the first layer 113a, the second layer 113b, and the third layer 113c.

[0117] The insulating layer 127 is provided on the insulating layer 125 so as to fill recesses formed in the insulating layer 125. The insulating layer 127 can be configured to overlap with the side surfaces of the pixel electrodes 111a, 111b, and 111c, the first layer 113a, the second layer 113b, and the third layer 113c, with the insulating layer 125 interposed therebetween.

[0118] Note that either the insulating layer 125 or the insulating layer 127 does not necessarily have to be provided. For example, when the insulating layer 125 is not provided, the insulating layer 127 can be in contact with the side surfaces of the first layer 113a, the second layer 113b, and the third layer 113c. The insulating layer 127 can be provided on the transistor-including layer 101 so as to fill the spaces between the EL layers of the light-emitting devices.

[0119] The fifth layer 114 and the common electrode 115 are provided over the first layer 113a, the second layer 113b, the third layer 113c, the insulating layer 125, and the insulating layer 127. Before the insulating layer 125 and the insulating layer 127 are provided, a step is generated between a region where the pixel electrode and the EL layer are provided and a region where the pixel electrode and the EL layer are not provided (a region between light-emitting devices). In the display device of one embodiment of the present invention, the insulating layer 125 and the insulating layer 127 can flatten the step, thereby improving the coverage of the fifth layer 114 and the common electrode 115. Therefore, poor connection due to a step in the common electrode 115 can be suppressed. Alternatively, an increase in electrical resistance caused by a local thinning of the common electrode 115 due to the step can be suppressed.

[0120] In this specification and the like, the term "step discontinuity" refers to a phenomenon in which a layer, film, or electrode is divided due to the shape of the surface on which it is formed (for example, a step or the like).

[0121] In order to improve the flatness of the surfaces on which the fifth layer 114 and the common electrode 115 are formed, it is preferable that the heights of the upper surfaces of the insulating layers 125 and 127 are the same or approximately the same as the height of the upper surface of at least one of the first layer 113a, the second layer 113b, and the third layer 113c. The upper surface of the insulating layer 127 preferably has a flat shape, and may have protrusions or recesses.

[0122] The insulating layer 125 has regions in contact with side surfaces of the first layer 113a, the second layer 113b, and the third layer 113c and functions as a protective insulating layer for the first layer 113a, the second layer 113b, and the third layer 113c. The insulating layer 125 can prevent impurities (oxygen, moisture, and the like) from entering the first layer 113a, the second layer 113b, and the third layer 113c from the side surfaces thereof, thereby providing a highly reliable display device.

[0123] If the width (thickness) of the insulating layer 125 in the region in contact with the side surfaces of the first layer 113a, the second layer 113b, and the third layer 113c is large in a cross-sectional view, the distance between the first layer 113a, the second layer 113b, and the third layer 113c may become large, resulting in a low aperture ratio. Also, if the width (thickness) of the insulating layer 125 is small, the effect of suppressing impurities from penetrating into the interior from the side surfaces of the first layer 113a, the second layer 113b, and the third layer 113c may become small. The width (thickness) of the insulating layer 125 in regions in contact with the side surfaces of the first layer 113a, the second layer 113b, and the third layer 113c is preferably 3 nm to 200 nm, more preferably 3 nm to 150 nm, even more preferably 5 nm to 150 nm, even more preferably 5 nm to 100 nm, even more preferably 10 nm to 100 nm, and even more preferably 10 nm to 50 nm. By setting the width (thickness) of the insulating layer 125 in the above range, a display device having a high aperture ratio and high reliability can be obtained.

[0124] The insulating layer 125 can be an insulating layer containing an inorganic material. For example, an inorganic insulating film such as an insulating oxide film, a nitride insulating film, an oxynitride insulating film, or a nitride oxide insulating film can be used for the insulating layer 125. The insulating layer 125 may have a single-layer structure or a stacked-layer structure. Examples of oxide insulating films include a silicon oxide film, an aluminum oxide film, a magnesium oxide film, an indium gallium zinc oxide film, a gallium oxide film, a germanium oxide film, an yttrium oxide film, a zirconium oxide film, a lanthanum oxide film, a neodymium oxide film, a hafnium oxide film, and a tantalum oxide film. Examples of nitride insulating films include a silicon nitride film and an aluminum nitride film. Examples of oxynitride insulating films include a silicon oxynitride film and an aluminum oxynitride film. Examples of nitride oxide insulating films include a silicon nitride oxide film and an aluminum nitride oxide film. In particular, aluminum oxide is preferable because it has a high etching selectivity with respect to the EL layer and functions to protect the EL layer in the formation of the insulating layer 127 described below. In particular, by using an inorganic insulating film such as an aluminum oxide film, a hafnium oxide film, or a silicon oxide film formed by the ALD method as the insulating layer 125, it is possible to form an insulating layer 125 with few pinholes and excellent function of protecting the EL layer.

[0125] In this specification and elsewhere, an oxynitride refers to a material whose composition contains more oxygen than nitrogen, and a nitride oxide refers to a material whose composition contains more nitrogen than oxygen. For example, silicon oxynitride refers to a material whose composition contains more oxygen than nitrogen, and silicon nitride oxide refers to a material whose composition contains more nitrogen than oxygen.

[0126] The insulating layer 125 can be formed by a sputtering method, a CVD method, a PLD method, an ALD method, etc. The insulating layer 125 is preferably formed by an ALD method, which has good coverage.

[0127] The insulating layer 127 provided on the insulating layer 125 has the function of flattening recesses formed in the insulating layer 125 between adjacent light-emitting devices. In other words, the insulating layer 127 improves the flatness of the surface on which the common electrode 115 is formed. An insulating layer containing an organic material can be suitably used as the insulating layer 127. For example, acrylic resin, polyimide resin, epoxy resin, imide resin, polyamide resin, polyimideamide resin, silicone resin, siloxane resin, benzocyclobutene-based resin, phenolic resin, and precursors of these resins can be used as the insulating layer 127. Alternatively, 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 as the insulating layer 127. Alternatively, a photosensitive resin can be used as the photosensitive resin. A photoresist can be used as the photosensitive resin. A positive-type material or a negative-type material can be used as the photosensitive resin.

[0128] The difference in height between the top surface of the insulating layer 127 and the top surface of any of the first layer 113a, the second layer 113b, and the third layer 113c is, for example, preferably 0.5 times or less, more preferably 0.3 times or less, the thickness of the insulating layer 127. For example, the insulating layer 127 may be provided so that the top surface of any of the first layer 113a, the second layer 113b, and the third layer 113c is higher than the top surface of the insulating layer 127. For example, the insulating layer 127 may be provided so that the top surface of the insulating layer 127 is higher than the top surface of the light-emitting layer included in the first layer 113a, the second layer 113b, or the third layer 113c.

[0129] It is preferable to provide protective layers 131 and 132 on the light emitting devices 130a, 130b, and 130c. By providing the protective layers 131 and 132, the reliability of the light emitting devices can be improved.

[0130] There is no limitation on the conductivity of the protective layers 131 and 132. The protective layers 131 and 132 can be made of at least one of an insulating film, a semiconductor film, and a conductive film.

[0131] The protective layers 131 and 132 have inorganic films, which can prevent oxidation of the common electrode 115 and prevent impurities (moisture, oxygen, etc.) from entering the light-emitting devices 130a, 130b, and 130c, thereby suppressing deterioration of the light-emitting devices and improving the reliability of the display device.

[0132] The protective layers 131 and 132 can be made of inorganic insulating films such as an insulating oxide film, an insulating nitride film, an insulating oxynitride film, and an insulating nitride oxide film. Examples of insulating oxide films include a silicon oxide film, an aluminum oxide film, a gallium oxide film, a germanium oxide film, an yttrium oxide film, a zirconium oxide film, a lanthanum oxide film, a neodymium oxide film, a hafnium oxide film, and a tantalum oxide film. Examples of insulating nitride films include a silicon nitride film and an aluminum nitride film. Examples of insulating oxynitride films include a silicon oxynitride film and an aluminum oxynitride film. Examples of insulating nitride oxide films include a silicon nitride oxide film and an aluminum nitride oxide film.

[0133] Each of the protective layers 131 and 132 preferably includes an insulating nitride film or an insulating nitride oxide film, and more preferably includes an insulating nitride film.

[0134] Alternatively, an inorganic film containing In-Sn oxide (also referred to as ITO), In-Zn oxide, Ga-Zn oxide, Al-Zn oxide, or indium gallium zinc oxide (In-Ga-Zn oxide, also referred to as IGZO) may be used for the protective layers 131 and 132. The inorganic film preferably has high resistance, specifically, preferably has higher resistance than the common electrode 115. The inorganic film may further contain nitrogen.

[0135] When light emitted from the light-emitting device is extracted through the protective layers 131 and 132, it is preferable that the protective layers 131 and 132 have high transparency to visible light. For example, ITO, IGZO, and aluminum oxide are preferable because they are inorganic materials that have high transparency to visible light.

[0136] The protective layers 131 and 132 may be, for example, a laminated structure of an aluminum oxide film and a silicon nitride film on the aluminum oxide film, or a laminated structure of an aluminum oxide film and an IGZO film on the aluminum oxide film. By using such a laminated structure, impurities (water, oxygen, etc.) can be prevented from entering the EL layer side.

[0137] Furthermore, the protective layers 131 and 132 may include an organic film. For example, the protective layer 132 may include both an organic film and an inorganic film.

[0138] Different film formation methods may be used for the protective layer 131 and the protective layer 132. Specifically, the protective layer 131 may be formed by the ALD method, and the protective layer 132 may be formed by the sputtering method.

[0139] The upper end portions of the pixel electrodes 111a, 111b, and 111c are not covered with an insulating layer, which allows the distance between adjacent light-emitting devices to be extremely narrow, thereby enabling a high-definition or high-resolution display device.

[0140] In this specification, etc., a device fabricated using a metal mask or FMM (fine metal mask, high-resolution metal mask) may be referred to as a device with an MM (metal mask) structure. Also, in this specification, etc., a device fabricated without using a metal mask or FMM may be referred to as a device with an MML (metal maskless) structure.

[0141] In this specification and the like, a structure in which different light-emitting layers are fabricated or painted separately for each color light-emitting device (here, blue (B), green (G), and red (R)) is sometimes referred to as an SBS (Side By Side) structure. The SBS structure allows the materials and configuration to be optimized for each light-emitting device, increasing the freedom of material and configuration selection and making it easier to improve brightness and reliability.

[0142] In addition, in this specification and the like, a light-emitting device capable of emitting white light may be referred to as a white light-emitting device. Note that a white light-emitting device can be combined with a colored layer (for example, a color filter) to realize a full-color display device.

[0143] Furthermore, light-emitting devices can be broadly divided into single structures and tandem structures. A single-structure device has one light-emitting unit between a pair of electrodes, and the light-emitting unit preferably includes one or more light-emitting layers. When two light-emitting layers are used to obtain white light emission, light-emitting layers can be selected so that the emission colors of the two light-emitting layers are complementary to each other. For example, by making the emission color of the first light-emitting layer and the emission color of the second light-emitting layer complementary to each other, a configuration in which the entire light-emitting device emits white light can be obtained. When three or more light-emitting layers are used to obtain white light emission, the emission colors of the three or more light-emitting layers can be combined to produce a configuration in which the entire light-emitting device emits white light.

[0144] A tandem-structure device preferably has two or more light-emitting units between a pair of electrodes, and each light-emitting unit preferably includes one or more light-emitting layers. To obtain white light, light from the light-emitting layers of the light-emitting units may be combined to obtain white light. The configuration for obtaining white light is the same as that of the single-structure device. In a tandem-structure device, it is preferable to provide a charge-generating layer between the light-emitting units.

[0145] Furthermore, when comparing the above-mentioned white light-emitting device (single structure or tandem structure) with a light-emitting device having an SBS structure, the light-emitting device having an SBS structure can reduce power consumption compared to the white light-emitting device. If you want to keep power consumption low, it is preferable to use a light-emitting device having an SBS structure. On the other hand, the manufacturing process of a white light-emitting device is simpler than that of a light-emitting device having an SBS structure, so it is preferable because it can reduce manufacturing costs or increase manufacturing yields.

[0146] The display device of this embodiment can reduce the distance between light-emitting devices. Specifically, the distance between light-emitting devices, between EL layers, or between pixel electrodes can be less than 10 μm, 5 μm or less, 3 μm or less, 2 μm or less, 1 μm or less, 500 nm or less, 200 nm or less, 100 nm or less, 90 nm or less, 70 nm or less, 50 nm or less, 30 nm or less, 20 nm or less, 15 nm or less, or 10 nm or less. In other words, the distance between the side surface of the first layer 113a and the side surface of the second layer 113b or the distance between the side surface of the second layer 113b and the side surface of the third layer 113c has a region of 1 μm or less, preferably a region of 0.5 μm (500 nm) or less, and more preferably a region of 100 nm or less.

[0147] A light-shielding layer may be provided on the surface of substrate 120 facing resin layer 122. Various optical members may be disposed on the outside of substrate 120. Examples of optical members include a polarizing plate, a retardation plate, a light diffusion layer (such as a diffusion film), an anti-reflection layer, and a light-collecting film. The outside of substrate 120 may also be provided with an anti-static film that prevents dust from adhering, a water-repellent film that makes it difficult for dirt to adhere, a hard coat film that prevents scratches from occurring during use, an impact absorbing layer, etc.

[0148] The substrate 120 can be made of glass, quartz, ceramic, sapphire, resin, metal, alloy, semiconductor, or the like. A material that transmits light is used for the substrate on the side from which light from the light-emitting device is extracted. Using a flexible material for the substrate 120 increases the flexibility of the display device, making it possible to realize a flexible display. A polarizing plate may also be used for the substrate 120.

[0149] The substrate 120 can be made of polyester resin such as polyethylene terephthalate (PET) or polyethylene naphthalate (PEN), polyacrylonitrile resin, acrylic resin, polyimide resin, polymethyl methacrylate resin, polycarbonate (PC) resin, polyethersulfone (PES) resin, polyamide resin (nylon, aramid, etc.), polysiloxane resin, cycloolefin resin, polystyrene resin, polyamideimide resin, polyurethane resin, polyvinyl chloride resin, polyvinylidene chloride resin, polypropylene resin, polytetrafluoroethylene (PTFE) resin, ABS resin, cellulose nanofiber, etc. The substrate 120 can also be made of glass having a thickness sufficient to provide flexibility.

[0150] When a circularly polarizing plate is superimposed on a display device, it is preferable that the display device has a substrate with high optical isotropy. A substrate with high optical isotropy has small birefringence (or a small amount of birefringence).

[0151] The absolute value of the retardation (phase difference) of a substrate having high optical isotropy is preferably 30 nm or less, more preferably 20 nm or less, and even more preferably 10 nm or less.

[0152] Examples of films with high optical isotropy include triacetyl cellulose (TAC, also known as cellulose triacetate) films, cycloolefin polymer (COP) films, cycloolefin copolymer (COC) films, and acrylic films.

[0153] Furthermore, when a film is used as a substrate, the film may absorb water, causing deformation such as wrinkles in the display panel. Therefore, it is preferable to use a film with low water absorption for the substrate. For example, it is preferable to use a film with a water absorption rate of 1% or less, more preferably 0.1% or less, and even more preferably 0.01% or less.

[0154] The resin layer 122 can be made of various curable adhesives, such as a photo-curable adhesive (e.g., an ultraviolet curable adhesive), a reactive curable adhesive, a thermosetting adhesive, or an anaerobic adhesive. Examples of such adhesives include epoxy resin, acrylic resin, silicone resin, phenolic resin, polyimide resin, imide resin, PVC (polyvinyl chloride) resin, PVB (polyvinyl butyral) resin, and EVA (ethylene vinyl acetate) resin. In particular, a material with low moisture permeability, such as epoxy resin, is preferable. Alternatively, a two-component resin may be used. Alternatively, an adhesive sheet or the like may be used.

[0155] Materials that can be used for conductive layers such as the gate, source, and drain of a transistor, as well as various wirings and electrodes that constitute a display device include metals such as aluminum, titanium, chromium, nickel, copper, yttrium, zirconium, molybdenum, silver, tantalum, and tungsten, and alloys containing these metals as main components, etc. Films containing these materials can be used as a single layer or a stacked layer structure.

[0156] Examples of light-transmitting conductive materials include conductive oxides such as indium oxide, indium tin oxide, indium zinc oxide, zinc oxide, and zinc oxide containing gallium, or graphene. Alternatively, metal materials such as gold, silver, platinum, magnesium, nickel, tungsten, chromium, molybdenum, iron, cobalt, copper, palladium, and titanium, or alloy materials containing such metal materials, can be used. Alternatively, nitrides of such metal materials (e.g., titanium nitride) can be used. When using metal materials or alloy materials (or their nitrides), it is preferable to thin them sufficiently to ensure light-transmitting properties. A stacked film of the above materials can also be used as the conductive layer. For example, a stacked film of an alloy of silver and magnesium and indium tin oxide is preferable because it can enhance conductivity. These materials can also be used for conductive layers such as various wirings and electrodes constituting a display device, and conductive layers (conductive layers functioning as pixel electrodes or common electrodes) in light-emitting devices.

[0157] Examples of insulating materials that can be used for each insulating layer include resins such as acrylic resin and epoxy resin, and inorganic insulating materials such as silicon oxide, silicon oxynitride, silicon nitride oxide, silicon nitride, and aluminum oxide.

[0158] As shown in FIG. 2A, a pixel can be configured to have four types of sub-pixels.

[0159] 2A shows a top view of the display device 100. The display device 100 has a display section in which a plurality of pixels 110 are arranged in a matrix, and a connection section 140 on the outside of the display section.

[0160] The pixel 110 shown in FIG. 2A is made up of four types of subpixels: subpixels 110a, 110b, 110c, and 110d.

[0161] For example, the subpixels 110a, 110b, 110c, and 110d may each have a light-emitting device that emits light of a different color. Examples of the subpixels 110a, 110b, 110c, and 110d include four subpixels of R, G, B, and white (W), four subpixels of R, G, B, and Y, and four subpixels of R, G, B, and infrared (IR).

[0162] FIG. 2A shows an example in which one pixel 110 is configured with two rows and three columns. The pixel 110 has three subpixels (subpixels 110a, 110b, and 110c) in the top row (first row) and three subpixels 110d in the bottom row (second row). In other words, the pixel 110 has the subpixels 110a and 110d in the left column (first column), the subpixels 110b and 110d in the center column (second column), and the subpixels 110c and 110d in the right column (third column). By aligning the subpixels in the top row and bottom row as shown in FIG. 2A, it is possible to efficiently remove dust and other particles that may occur during the manufacturing process. This makes it possible to provide a display device with high display quality.

[0163] Figure 2B shows a cross-sectional view taken along dashed line X3-X4 in Figure 2A. The configuration shown in Figure 2B is the same as that shown in Figure 1B, except that it includes a light-emitting device 130d. Therefore, a description of the same parts as those in Figure 1B will be omitted.

[0164] 2B, display device 100 has light-emitting devices 130a, 130b, 130c, and 130d provided on transistor-containing layer 101, and protective layers 131 and 132 provided to cover these light-emitting devices. Substrate 120 is bonded to protective layer 132 with resin layer 122. Insulating layers 125 and 127 are provided in the regions between adjacent light-emitting devices.

[0165] The light emitting devices 130a, 130b, 130c, and 130d each emit light of a different color, and preferably, the light emitting devices 130a, 130b, 130c, and 130d emit light of four colors, for example, red (R), green (G), blue (B), and white (W).

[0166] Light-emitting device 130d has a pixel electrode 111d on the transistor-containing layer 101, an island-shaped fourth layer 113d on pixel electrode 111d, an island-shaped fifth layer 114 on fourth layer 113d, and a common electrode 115 on fifth layer 114. In light-emitting device 130d, fourth layer 113d and fifth layer 114 can be collectively referred to as an EL layer.

[0167] The three sub-pixels 110d may each have an independent light-emitting device 130d, or may share one light-emitting device 130d. That is, the pixel 110 may have one or three light-emitting devices 130d.

[0168] [Pixel layout] Next, pixel layouts different from those shown in Figures 1A and 2A will be described. There are no particular limitations on the arrangement of sub-pixels, and various methods can be applied. Examples of sub-pixel arrangements include a stripe arrangement, an S-stripe arrangement, a matrix arrangement, a delta arrangement, a Bayer arrangement, and a pentile arrangement.

[0169] Examples of the top surface shape of the sub-pixel include a triangle, a quadrangle (including a rectangle and a square), a polygon such as a pentagon, a polygon with rounded corners, an ellipse, a circle, etc. Here, the top surface shape of the sub-pixel corresponds to the top surface shape of the light-emitting region of the light-emitting device.

[0170] An S-stripe arrangement is applied to the pixel 110 shown in Fig. 3A. The pixel 110 shown in Fig. 3A is composed of three subpixels: subpixels 110a, 110b, and 110c. For example, as shown in Fig. 4A, the subpixel 110a may be a blue subpixel B, the subpixel 110b may be a red subpixel R, and the subpixel 110c may be a green subpixel G.

[0171] The pixel 110 shown in FIG. 3B includes a subpixel 110a having a generally trapezoidal top surface shape with rounded corners, a subpixel 110b having a generally triangular top surface shape with rounded corners, and a subpixel 110c having a generally rectangular or hexagonal top surface shape with rounded corners. The subpixel 110a has a larger light-emitting area than the subpixel 110b. Thus, the shape and size of each subpixel can be determined independently. For example, the subpixel with a more reliable light-emitting device can be made smaller in size. For example, as shown in FIG. 4B, the subpixel 110a may be a green subpixel G, the subpixel 110b may be a red subpixel R, and the subpixel 110c may be a blue subpixel B.

[0172] The pixels 124a and 124b shown in Fig. 3C are arranged in a Pentile array. Fig. 3C shows an example in which pixel 124a, which has subpixels 110a and 110b, and pixel 124b, which has subpixels 110b and 110c, are arranged alternately. For example, as shown in Fig. 4C, subpixel 110a may be a red subpixel R, subpixel 110b may be a green subpixel G, and subpixel 110c may be a blue subpixel B.

[0173] 3D and 3E are arranged in a delta configuration. Pixel 124a has two subpixels (subpixels 110a and 110b) in the top row (first row) and one subpixel (subpixel 110c) in the bottom row (second row). Pixel 124b has one subpixel (subpixel 110c) in the top row (first row) and two subpixels (subpixels 110a and 110b) in the bottom row (second row). For example, as shown in FIG. 4D, subpixel 110a may be a red subpixel R, subpixel 110b may be a green subpixel G, and subpixel 110c may be a blue subpixel B.

[0174] FIG. 3D shows an example in which each subpixel has a substantially rectangular shape with rounded corners when viewed from above, and FIG. 3E shows an example in which each subpixel has a circular shape when viewed from above.

[0175] In photolithography, the finer the pattern to be processed, the more significant the effect of light diffraction becomes. This reduces the fidelity of the photomask pattern when it is transferred by exposure, making it difficult to process the resist mask into the desired shape. Therefore, even if the photomask pattern is rectangular, it is likely to have rounded corners. As a result, the top surface shape of the subpixel may become a polygon with rounded corners, an ellipse, a circle, or the like.

[0176] Furthermore, in a manufacturing method of a display device according to one embodiment of the present invention, the EL layer is processed into an island shape using a resist mask. The resist film formed on the EL layer needs to be cured at a temperature lower than the heat resistance temperature of the EL layer. Therefore, depending on the heat resistance temperature of the material for the EL layer and the curing temperature of the resist material, the resist film may not be cured sufficiently. A resist film that is not cured sufficiently may have a shape that is different from the desired shape during processing. As a result, the top surface shape of the EL layer may become a polygon with rounded corners, an ellipse, a circle, or the like. For example, when a resist mask with a square top surface shape is formed, a resist mask with a circular top surface shape may be formed, resulting in a circular top surface shape of the EL layer.

[0177] In order to obtain a desired top surface shape for the EL layer, a technique for correcting the mask pattern in advance (OPC (Optical Proximity Correction) technique) may be used so that the design pattern and the transfer pattern match. Specifically, OPC technique adds correction patterns to the corners of the figures on the mask pattern.

[0178] In addition, even in the pixel 110 to which the stripe arrangement shown in FIG. 1A is applied, for example, as shown in FIG. 4E, the subpixel 110a can be a red subpixel R, the subpixel 110b can be a green subpixel G, and the subpixel 110c can be a blue subpixel B.

[0179] The pixel 110 shown in FIGS. 5A to 5C is arranged in a stripe pattern.

[0180] FIG. 5A shows an example in which each subpixel has a rectangular top surface shape, FIG. 5B shows an example in which each subpixel has a top surface shape that combines two semicircles and a rectangle, and FIG. 5C shows an example in which each subpixel has an elliptical top surface shape.

[0181] The pixels 110 shown in FIGS. 5D to 5F are arranged in a matrix.

[0182] FIG. 5D is an example in which each subpixel has a square top surface shape, FIG. 5E is an example in which each subpixel has an approximately square top surface shape with rounded corners, and FIG. 5F is an example in which each subpixel has a circular top surface shape.

[0183] The pixel 110 shown in FIGS. 5A to 5F is composed of four subpixels: subpixels 110a, 110b, 110c, and 110d. Each of the subpixels 110a, 110b, 110c, and 110d has a light-emitting device that emits light of a different color. For example, the subpixels 110a, 110b, 110c, and 110d can be red, green, blue, and white subpixels, respectively. For example, as shown in FIGS. 6A and 6B, the subpixels 110a, 110b, 110c, and 110d can be red, green, blue, and white subpixels, respectively. Alternatively, the subpixels 110a, 110b, 110c, and 110d can be red, green, blue, and infrared-emitting subpixels, respectively.

[0184] 5G shows an example in which one pixel 110 is configured with two rows and three columns. The pixel 110 has three subpixels (subpixels 110a, 110b, and 110c) in the top row (first row) and one subpixel (subpixel 110d) in the bottom row (second row). In other words, the pixel 110 has the subpixel 110a in the left column (first column), the subpixel 110b in the center column (second column), the subpixel 110c in the right column (third column), and further has the subpixel 110d across these three columns.

[0185] In the pixel 110 shown in Figures 2A and 5G, for example, as shown in Figures 6C and 6D, the subpixel 110a can be a red subpixel R, the subpixel 110b can be a green subpixel G, the subpixel 110c can be a blue subpixel B, and the subpixel 110d can be a white subpixel W.

[0186] An electronic device including the display device of one embodiment of the present invention can have one or both of a flashlight function using the subpixel W and a lighting function using the subpixel W.

[0187] Here, the white light emitted by the subpixel W may be light with high instantaneous brightness, such as a flashlight or strobe light, or light with high color rendering, such as a reading light. When using white light as a reading light, the color temperature of the white light emission can be lowered. For example, by using white light with an incandescent color (e.g., 2500K or more but less than 3250K) or a warm white color (e.g., 3250K or more but less than 3800K), the light source can be gentle on the user's eyes.

[0188] The strobe light function can be realized by, for example, repeating light emission and non-emission in a short cycle, while the flash light function can be realized by, for example, generating a flash of light by instantaneous discharge utilizing the principle of an electric double layer.

[0189] For example, if the electronic device 70 is provided with a camera function, by utilizing a strobe light function or a flash light function, images can be captured with the electronic device 70 even at night, as shown in FIG. 7A. Here, the display device 100 included in the electronic device 70 functions as a surface light source, which is less likely to cast shadows on the subject, allowing for beautiful images to be captured. Note that the strobe light function or flash light function can be used at times other than night. When the electronic device 70 is provided with a strobe light function or a flash light function, the color temperature of the white light emitted can be increased. For example, the color temperature of the light emitted from the electronic device 70 can be white (3800K or more and less than 4500K), daylight white (4500K or more and less than 5500K), or daylight white (5500K or more and less than 7100K).

[0190] Furthermore, if the flash emits light that is stronger than necessary, areas that are normally bright or dark may appear all white in the image (so-called whiteout). On the other hand, if the flash is too weak, dark areas may appear all black in the image (so-called blackout). To address this issue, the display device may be configured to detect the brightness around the subject using a light-receiving device, so that the light-emitting devices of the sub-pixels can adjust the light intensity to an optimal level. In other words, the electronic device 70 can also function as an exposure meter.

[0191] The strobe light function and flashlight function can also be used for crime prevention or self-defense purposes. For example, as shown in FIG. 7B, the electronic device 70 can be made to emit light toward a thug to frighten him. In an emergency, such as when one is attacked by a thug, it may be difficult to remain calm and aim the light of a self-defense light, which has a narrow light-emitting range, toward the thug's face. In contrast, because the display device 100 included in the electronic device 70 is a surface light source, the light emitted from the display device 100 can be brought into the thug's field of vision even if the orientation of the display device 100 is slightly off.

[0192] As shown in FIG. 7B, when the display device 100 is used as a flashlight for crime prevention or self-defense, it is preferable to increase the brightness compared to the nighttime shooting shown in FIG. 7A. Furthermore, by making the display device 100 emit light intermittently multiple times, it is possible to more easily intimidate an assailant. Furthermore, the electronic device 70 may emit a relatively loud sound, such as a buzzer, to call for help from those nearby. Emitting the sound near the assailant's face is preferable because it can intimidate the assailant not only by the light but also by the sound.

[0193] Furthermore, when improving the color rendering of the light emitted from the light-emitting device of subpixel W, it is preferable to increase the number of light-emitting layers included in the light-emitting device or the types of light-emitting materials included in the light-emitting layers, thereby obtaining a broader emission spectrum with intensity over a wider wavelength range, and exhibiting light emission with higher color rendering that is closer to sunlight.

[0194] For example, as shown in FIG. 7C , an electronic device 70 capable of emitting light with high color rendering properties may be used as a reading lamp. In FIG. 7C , the electronic device 70 is fixed to a desk 74 using a support 72. By using such a support 72, the electronic device 70 can be used as a reading lamp. The display device 100 included in the electronic device 70 functions as a surface light source, which makes it less likely to cast shadows on an object (a book in FIG. 7C ), and the distribution of reflected light from the object is gentle, making it less likely for light to be reflected. This improves the visibility of the object, making it easier to see. In addition, the emission spectrum of a white-emitting light-emitting device is broad, which relatively reduces blue light. This can reduce eye strain and other issues experienced by users of the electronic device 70.

[0195] The configuration of the support 72 is not limited to that shown in Fig. 7C. It is sufficient to provide an appropriate arm or movable portion so as to maximize the range of motion. Also, in Fig. 7C, the support 72 holds the electronic device 70 by sandwiching it, but the present invention is not limited to this. For example, a configuration using a magnet, a suction cup, or the like may be used as appropriate.

[0196] The emission color for the lighting application is preferably white, but there is no particular limitation on the emission color for lighting application, and the user can appropriately select one or more optimal emission colors from white, blue, purple, blue-purple, green, yellow-green, yellow, orange, red, and the like.

[0197] The display device according to one embodiment of the present invention may include a light-receiving device in a pixel.

[0198] Of the four types of sub-pixels included in pixel 110 shown in FIG. 2A, three may be configured to have a light-emitting device, and the remaining one may be configured to have a light-receiving device.

[0199] The light receiving device can be, for example, a pn-type or pin-type photodiode. The light receiving device functions as a photoelectric conversion device (also called a photoelectric conversion element) that detects light incident on the light receiving device and generates electric charges. The amount of electric charges generated by the light receiving device is determined based on the amount of light incident on the light receiving device.

[0200] In particular, it is preferable to use an organic photodiode having a layer containing an organic compound as the light-receiving device. Organic photodiodes can be easily made thin, lightweight, and large in area, and have a high degree of freedom in shape and design, making them applicable to a variety of display devices.

[0201] In one embodiment of the present invention, an organic EL device is used as the light-emitting device, and an organic photodiode is used as the light-receiving device. The organic EL device and the organic photodiode can be formed on the same substrate. Therefore, the organic photodiode can be built into a display device using the organic EL device.

[0202] The light-receiving device has an active layer that functions as at least a photoelectric conversion layer between a pair of electrodes. In this specification and the like, one of the pair of electrodes may be referred to as a pixel electrode and the other as a common electrode.

[0203] For example, the subpixels 110a, 110b, and 110c may be subpixels of three colors, R, G, and B, and the subpixel 110d may be a subpixel having a light-receiving device. In this case, the fourth layer 113d has at least an active layer.

[0204] Of the pair of electrodes that a light-receiving device has, one electrode functions as an anode and the other electrode functions as a cathode. The following describes an example in which the pixel electrode functions as the anode and the common electrode functions as the cathode. The light-receiving device can detect light incident on the light-receiving device, generate electric charges, and extract them as a current by applying a reverse bias between the pixel electrode and the common electrode. Alternatively, the pixel electrode may function as a cathode and the common electrode may function as an anode.

[0205] The same manufacturing method as for the light-emitting device can be applied to the light-receiving device. The island-shaped active layer (also called the photoelectric conversion layer) of the light-receiving device is formed not using a fine metal mask but by forming a film that will become the active layer on the entire surface and then processing it, so that the island-shaped active layer can be formed with a uniform thickness. In addition, by providing a sacrificial layer on the active layer, damage to the active layer during the manufacturing process of the display device can be reduced, thereby improving the reliability of the light-receiving device.

[0206] Here, a layer shared by a light-receiving device and a light-emitting device may have different functions in the light-emitting device and in the light-receiving device. In this specification, components may be referred to based on their functions in the light-emitting device. For example, a hole injection layer functions as a hole injection layer in the light-emitting device and as a hole transport layer in the light-receiving device. Similarly, an electron injection layer functions as an electron injection layer in the light-emitting device and as an electron transport layer in the light-receiving device. Furthermore, a layer shared by a light-receiving device and a light-emitting device may have the same function in the light-emitting device and in the light-receiving device. A hole transport layer functions as a hole transport layer in both the light-emitting device and the light-receiving device, and an electron transport layer functions as an electron transport layer in both the light-emitting device and the light-receiving device.

[0207] The active layer of the light-receiving device includes a semiconductor. Examples of the semiconductor include inorganic semiconductors such as silicon and organic semiconductors containing organic compounds. In this embodiment, an example in which an organic semiconductor is used as the semiconductor of the active layer is shown. By using an organic semiconductor, the light-emitting layer and the active layer can be formed by the same method (for example, vacuum deposition), which is preferable because it allows the use of a common manufacturing device.

[0208] The active layer is made of n-type semiconductor material, such as fullerene (e.g., C 60 Fullerene, C 70 Examples of electron-accepting organic semiconductor materials include fullerenes and fullerene derivatives. Fullerenes have a soccer ball-like shape, which is energetically stable. Fullerenes have deep (low) HOMO and LUMO levels. Because fullerenes have a deep LUMO level, they have extremely high electron-accepting (acceptor) properties. Normally, when the π-electron conjugation (resonance) spreads on a plane, as in benzene, the electron-donating (donor) properties increase, but fullerenes have a spherical shape, so they have high electron-accepting properties despite the wide spread of π-electrons. High electron-accepting properties allow charge separation to occur quickly and efficiently, making them useful as light-receiving devices. C 60 Fullerene, C70 Both fullerenes and fluorenes have a wide absorption band in the visible light region, especially C 70 Fullerene is C 60 It is preferable because it has a larger π-electron conjugated system than fullerene and has a wide absorption band in the long wavelength region. Other fullerene derivatives include [6,6]-Phenyl-C71-butyric acid methyl ester (abbreviation: PC70BM), [6,6]-Phenyl-C61-butyric acid methyl ester (abbreviation: PC60BM), and 1',1'',4',4''-Tetrahydro-di[1,4]methanonaphthaleno[1,2:2',3',56,60:2'',3''][5,6]fullerene-C60 (abbreviation: ICBA).

[0209] Furthermore, examples of n-type semiconductor materials include metal complexes having a quinoline skeleton, metal complexes having a benzoquinoline skeleton, metal complexes having an oxazole skeleton, metal complexes having a thiazole skeleton, oxadiazole derivatives, triazole derivatives, imidazole derivatives, oxazole derivatives, thiazole derivatives, phenanthroline derivatives, quinoline derivatives, benzoquinoline derivatives, quinoxaline derivatives, dibenzoquinoxaline derivatives, pyridine derivatives, bipyridine derivatives, pyrimidine derivatives, naphthalene derivatives, anthracene derivatives, coumarin derivatives, rhodamine derivatives, triazine derivatives, and quinone derivatives.

[0210] Examples of p-type semiconductor materials for the active layer include electron-donating organic semiconductor materials such as copper(II) phthalocyanine (CuPc), tetraphenyldibenzoperiflanthene (DBP), zinc phthalocyanine (ZnPc), tin(II) phthalocyanine (SnPc), and quinacridone.

[0211] Examples of p-type semiconductor materials include carbazole derivatives, thiophene derivatives, furan derivatives, compounds having an aromatic amine skeleton, etc. Examples of p-type semiconductor materials include naphthalene derivatives, anthracene derivatives, pyrene derivatives, triphenylene derivatives, fluorene derivatives, pyrrole derivatives, benzofuran derivatives, benzothiophene derivatives, indole derivatives, dibenzofuran derivatives, dibenzothiophene derivatives, indolocarbazole derivatives, porphyrin derivatives, phthalocyanine derivatives, naphthalocyanine derivatives, quinacridone derivatives, polyphenylenevinylene derivatives, polyparaphenylene derivatives, polyfluorene derivatives, polyvinylcarbazole derivatives, polythiophene derivatives, etc.

[0212] The HOMO level of the electron-donating organic semiconductor material is preferably shallower (higher) than the HOMO level of the electron-accepting organic semiconductor material, and the LUMO level of the electron-donating organic semiconductor material is preferably shallower (higher) than the LUMO level of the electron-accepting organic semiconductor material.

[0213] It is preferable to use a spherical fullerene as the electron-accepting organic semiconductor material and a planar organic semiconductor material as the electron-donating organic semiconductor material. Molecules with similar shapes tend to aggregate together, and when molecules of the same type aggregate, the energy levels of their molecular orbitals become close, which can improve carrier transport properties.

[0214] For example, the active layer is preferably formed by co-evaporating an n-type semiconductor and a p-type semiconductor, or may be formed by laminating an n-type semiconductor and a p-type semiconductor.

[0215] The light-receiving device may further include, as a layer other than the active layer, a layer containing a substance with high hole-transporting properties, a substance with high electron-transporting properties, a bipolar substance (a substance with high electron-transporting properties and high hole-transporting properties), etc. Furthermore, without being limited to the above, the light-receiving device may further include a layer containing a substance with high hole-injecting properties, a hole-blocking material, a substance with high electron-injecting properties, an electron-blocking material, etc.

[0216] The light-receiving device can be made of either a low-molecular-weight compound or a high-molecular-weight compound, and may contain an inorganic compound. The layers constituting the light-receiving device can be formed by a method such as vapor deposition (including vacuum vapor deposition), transfer, printing, inkjet printing, or coating.

[0217] For example, polymer compounds such as poly(3,4-ethylenedioxythiophene) / poly(styrenesulfonic acid) (PEDOT / PSS) and inorganic compounds such as molybdenum oxide and copper iodide (CuI) can be used as hole-transporting materials, and inorganic compounds such as zinc oxide (ZnO) can be used as electron-transporting materials.

[0218] In addition, the active layer can be made of a polymer compound such as Poly[[4,8-bis[5-(2-ethylhexyl)-2-thienyl]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl]-2,5-thiophenediyl[5,7-bis(2-ethylhexyl)-4,8-dioxo-4H,8H-benzo[1,2-c:4,5-c']dithiophene-1,3-diyl]]polymer (abbreviated as PBDB-T) or a PBDB-T derivative, which functions as a donor. For example, an acceptor material can be dispersed in PBDB-T or a PBDB-T derivative.

[0219] The active layer may also contain a mixture of three or more materials. For example, in order to broaden the absorption wavelength range, a third material may be mixed in addition to an n-type semiconductor material and a p-type semiconductor material. In this case, the third material may be a low-molecular-weight compound or a high-molecular-weight compound.

[0220] In a display device having a light-emitting device and a light-receiving device in each pixel, the pixel has a light-receiving function, and therefore it is possible to detect contact or proximity of an object while displaying an image. For example, in addition to displaying an image using all of the sub-pixels of the display device, some of the sub-pixels can emit light as a light source, while other sub-pixels can detect light, and the remaining sub-pixels can display an image.

[0221] A display device according to one embodiment of the present invention has a display portion in which light-emitting devices are arranged in a matrix, and can display an image on the display portion. Furthermore, light-receiving devices are arranged in a matrix on the display portion, and the display portion has an imaging function and / or a sensing function in addition to an image display function. The display portion can be used as an image sensor or a touch sensor. That is, by detecting light in the display portion, an image can be captured or the proximity or contact of an object (such as a finger, a hand, or a pen) can be detected. Furthermore, the display device according to one embodiment of the present invention can use a light-emitting device as a light source for a sensor. Therefore, a light-receiving portion and a light source are not required separately from the display device, and the number of components in an electronic device can be reduced.

[0222] In a display device of one embodiment of the present invention, when light emitted from a light-emitting device included in a display portion is reflected (or scattered) by an object, the light-receiving device can detect the reflected light (or scattered light). Therefore, imaging or touch detection is possible even in a dark place.

[0223] When the light receiving device is used as an image sensor, the display device can capture an image using the light receiving device. For example, the display device of the present embodiment can be used as a scanner.

[0224] For example, an image sensor can be used to acquire data related to biometric information such as fingerprints and palm prints. That is, a biometric authentication sensor can be built into the display device. By building a biometric authentication sensor into the display device, the number of components in the electronic device can be reduced compared to when a biometric authentication sensor is provided separately from the display device, and the electronic device can be made smaller and lighter.

[0225] Furthermore, when the light-receiving device is used as a touch sensor, the display device can detect the proximity or contact of an object using the light-receiving device.

[0226] The pixel shown in FIGS. 8A and 8B has subpixels G, B, R, and PS.

[0227] A stripe arrangement is applied to the pixels shown in Fig. 8A, and a matrix arrangement is applied to the pixels shown in Fig. 8B.

[0228] The pixel shown in FIGS. 8C and 8D has a subpixel G, a subpixel B, a subpixel R, a subpixel PS, and a subpixel IRS.

[0229] 8C and 8D show an example in which one pixel is arranged across two rows and three columns. The top row (first row) has three subpixels (subpixel G, subpixel B, and subpixel R). In FIG. 8C, the bottom row (second row) has three subpixels (one subpixel PS and two subpixels IRS). In contrast, in FIG. 8D, the bottom row (second row) has two subpixels (one subpixel PS and one subpixel IRS). As shown in FIG. 8C, by aligning the subpixels in the top row and bottom row, it is possible to efficiently remove dust and other impurities that may occur during the manufacturing process. This makes it possible to provide a display device with high display quality. Note that the subpixel layout is not limited to the configurations shown in FIGS. 8A to 8D.

[0230] Subpixel R has a light-emitting device that emits red light, subpixel G has a light-emitting device that emits green light, and subpixel B has a light-emitting device that emits blue light.

[0231] The subpixels PS and IRS each have a light receiving device, and there is no particular limitation on the wavelength of light that the subpixels PS and IRS detect.

[0232] 8C, the two subpixels IRS may each have an independent light receiving device, or may share one light receiving device. That is, the pixel 110 shown in FIG. 8C may have one light receiving device for the subpixel PS and one or two light receiving devices for the subpixel IRS.

[0233] The light-receiving area of ​​the sub-pixel PS is smaller than that of the sub-pixel IRS. The smaller the light-receiving area, the narrower the imaging range, making it possible to suppress blurring in the imaging results and improve resolution. Therefore, using the sub-pixel PS makes it possible to capture images with higher definition or resolution than when using the sub-pixel IRS. For example, the sub-pixel PS can be used to capture images for personal authentication using fingerprints, palm prints, irises, pulse patterns (including vein patterns and artery patterns), faces, etc.

[0234] The light receiving device included in the subpixel PS preferably detects visible light, and preferably detects one or more of the colors blue, purple, blue-purple, green, yellow-green, yellow, orange, red, etc. The light receiving device included in the subpixel PS may also detect infrared light.

[0235] The sub-pixel IRS can be used as a touch sensor (also called a direct touch sensor) or a near-touch sensor (also called a hover sensor, hover touch sensor, non-contact sensor, or touchless sensor). The wavelength of light to be detected by the sub-pixel IRS can be determined appropriately depending on the application. For example, it is preferable that the sub-pixel IRS detects infrared light. This enables touch detection even in dark places.

[0236] Here, the touch sensor or near-touch sensor can detect the proximity or contact of an object (such as a finger, hand, or pen).

[0237] A touch sensor can detect an object when the display device and the object are in direct contact with each other. A near-touch sensor can detect an object even if the object does not touch the display device. For example, a configuration in which the display device can detect an object when the distance between the display device and the object is between 0.1 mm and 300 mm, preferably between 3 mm and 50 mm, is preferred. This configuration allows the object to operate the display device without directly touching it; in other words, it allows the display device to be operated in a non-contact (touchless) manner. This configuration reduces the risk of the display device becoming dirty or scratched, or allows the object to operate the display device without directly touching dirt (e.g., dust, viruses, etc.) adhering to the display device.

[0238] Furthermore, the display device of one embodiment of the present invention can have a variable refresh rate. For example, the refresh rate can be adjusted (for example, within a range of 1 Hz to 240 Hz) depending on the content displayed on the display device, thereby reducing power consumption. Furthermore, the drive frequency of the touch sensor or near-touch sensor may be changed depending on the refresh rate. For example, when the refresh rate of the display device is 120 Hz, the drive frequency of the touch sensor or near-touch sensor can be set to a frequency higher than 120 Hz (typically 240 Hz). This configuration enables low power consumption and an increased response speed of the touch sensor or near-touch sensor.

[0239] The display device 100 shown in FIGS. 8E to 8G includes, between a substrate 351 and a substrate 359, a layer 353 having a light-receiving device, a functional layer 355, and a layer 357 having a light-emitting device.

[0240] The functional layer 355 has a circuit for driving the light-receiving device and a circuit for driving the light-emitting device. The functional layer 355 may be provided with switches, transistors, capacitors, resistors, wiring, terminals, etc. Note that when the light-emitting device and the light-receiving device are driven by a passive matrix method, a configuration without switches and transistors may be used.

[0241] For example, as shown in FIG. 8E, when a finger 352 touches the display device 100, light emitted from a light-emitting device in a layer 357 having light-emitting devices is reflected by the finger 352, and the light-receiving device in a layer 353 having light-receiving devices detects the reflected light. This makes it possible to detect that the finger 352 has touched the display device 100. Alternatively, as shown in FIGS. 8F and 8G, the display device may have a function to detect or capture an object that is close to (not in contact with) the display device. FIG. 8F shows an example of detecting a human finger, and FIG. 8G shows an example of detecting information about the periphery, surface, or interior of a human eye (such as the number of blinks, eyeball movement, and eyelid movement).

[0242] By incorporating two types of light-receiving devices into one pixel, two additional functions can be added in addition to the display function, making it possible to multi-function the display device.

[0243] In order to capture high-resolution images, it is preferable that sub-pixels PS be provided in all pixels of the display device. On the other hand, sub-pixels IRS used in touch sensors or near-touch sensors do not require higher accuracy than detection using sub-pixels PS, so they may be provided in only some of the pixels of the display device. By making the number of sub-pixels IRS in the display device smaller than the number of sub-pixels PS, the detection speed can be increased.

[0244] As described above, by incorporating two types of light-receiving devices into one pixel, the display device of one embodiment of the present invention can add two functions in addition to a display function, thereby enabling the display device to have multiple functions. For example, a high-resolution imaging function and a sensing function such as a touch sensor or a near-touch sensor can be realized. Furthermore, by combining a pixel incorporating two types of light-receiving devices with a pixel having a different configuration, the functions of the display device can be further increased. For example, a pixel including a light-emitting device that emits infrared light or various sensor devices can be used.

[0245] [Example of a display device manufacturing method] Next, an example of a manufacturing method of a display device will be described with reference to FIGS. 9 to 17. FIGS. 9A to 9E are top views illustrating a manufacturing method of a display device. FIGS. 10A to 10C show cross-sectional views taken along dashed lines X1-X2 and Y1-Y2 in FIG. 1A side by side. FIGS. 11 to 15 and 16A are similar to FIG. 10. FIGS. 16B to 16D show cross-sectional views taken along dashed lines X1-X2 in FIG. 1A. FIG. 16E shows a cross-sectional view taken along dashed line Y1-Y2 in FIG. 1A. FIGS. 17A to 17F show enlarged views illustrating the cross-sectional structure of the insulating layer 127 and its surroundings.

[0246] Thin films (insulating films, semiconductor films, conductive films, etc.) that make up display devices can be formed using methods such as sputtering, CVD, vacuum evaporation, pulsed laser deposition (PLD), and ALD. CVD methods include PECVD and thermal CVD. One type of thermal CVD method is metal organic chemical vapor deposition (MOCVD).

[0247] Furthermore, thin films (insulating films, semiconductor films, conductive films, etc.) that constitute the display device can be formed by methods such as spin coating, dipping, spray coating, inkjet, dispensing, screen printing, offset printing, doctor knife, slit coating, roll coating, curtain coating, and knife coating.

[0248] In particular, vacuum processes such as vapor deposition and solution processes such as spin coating and inkjet printing can be used to fabricate light-emitting devices. Vapor deposition methods include physical vapor deposition (PVD) methods such as sputtering, ion plating, ion beam deposition, molecular beam deposition, and vacuum deposition, as well as chemical vapor deposition (CVD). In particular, functional layers included in the EL layer (e.g., hole injection layer, hole transport layer, light-emitting layer, electron transport layer, electron injection layer) can be formed by vapor deposition (e.g., vacuum deposition), coating methods (e.g., dip coating, die coating, bar coating, spin coating, spray coating), printing methods (e.g., inkjet printing, screen printing, offset printing, flexography, gravure printing, microcontact printing, etc.).

[0249] Furthermore, when processing the thin film that constitutes the display device, a photolithography method or the like can be used. Alternatively, the thin film may be processed by a nanoimprint method, a sandblasting method, a lift-off method, or the like. Furthermore, the island-shaped thin film may be directly formed by a film formation method using a shielding mask such as a metal mask.

[0250] There are two typical photolithography methods: one is to form a resist mask on the thin film to be processed, process the thin film by etching or the like, and then remove the resist mask; the other is to form a photosensitive thin film, and then process the thin film into the desired shape by exposure and development.

[0251] In photolithography, the light used for exposure can be, for example, i-line (wavelength 365 nm), g-line (wavelength 436 nm), h-line (wavelength 405 nm), or a mixture of these. Other light sources that can be used include ultraviolet light, KrF laser light, and ArF laser light. Exposure can also be performed using immersion exposure technology. Extreme ultraviolet (EUV) light or X-rays can also be used as the light used for exposure. Instead of light used for exposure, an electron beam can also be used. Extreme ultraviolet light, X-rays, or an electron beam are preferred because they enable extremely fine processing. When exposure is performed by scanning a beam such as an electron beam, a photomask is not required.

[0252] For etching the thin film, dry etching, wet etching, sandblasting, or the like can be used.

[0253] First, as shown in FIG. 10A, a conductive film 111 is formed over a layer 101 including a transistor.

[0254] Then, a first layer 113A is formed on the conductive film 111, a first sacrificial layer 118A is formed on the first layer 113A, and a second sacrificial layer 119A is formed on the first sacrificial layer 118A.

[0255] 10A, in the cross-sectional view between Y1 and Y2, the end of the first layer 113A on the connection portion 140 side is located inside the end of the first sacrificial layer 118A. For example, by using a mask for defining the film formation area (also called an area mask or a rough metal mask to distinguish it from a fine metal mask), it is possible to vary the regions where the first layer 113A, the first sacrificial layer 118A, and the second sacrificial layer 119A are formed. In one embodiment of the present invention, a light-emitting device is formed using a resist mask. However, by combining this with an area mask as described above, a light-emitting device can be fabricated using a relatively simple process.

[0256] The conductive film 111 is a layer that will be processed later to become the pixel electrodes 111a, 111b, and 111c and the conductive layer 123. Therefore, the structure applicable to the pixel electrodes described above can be applied to the conductive film 111. The conductive film 111 can be formed by, for example, sputtering or vacuum evaporation.

[0257] The first layer 113A is a layer that will later become the first layer 113a. Therefore, the above-mentioned configurations applicable to the first layer 113a can be applied thereto. The first layer 113A can be formed by a method such as a vapor deposition method (including a vacuum vapor deposition method), a transfer method, a printing method, an inkjet method, or a coating method. The first layer 113A is preferably formed by a vapor deposition method. When forming a film using a vapor deposition method, a premixed material may be used. In this specification and the like, a premixed material is a composite material in which multiple materials are blended or mixed in advance.

[0258] The first sacrificial layer 118A and the second sacrificial layer 119A are made of a film that is highly resistant to the processing conditions of the first layer 113A and the second layer 113B and third layer 113C formed in later steps, specifically, a film that has a large etching selectivity with respect to various EL layers.

[0259] The first sacrificial layer 118A and the second sacrificial layer 119A can be formed by, for example, sputtering, ALD (including thermal ALD and PEALD), CVD, or vacuum deposition. The first sacrificial layer 118A, which is formed on and in contact with the EL layer, is preferably formed using a method that causes less damage to the EL layer than the second sacrificial layer 119A. For example, the first sacrificial layer 118A is preferably formed using ALD or vacuum deposition rather than sputtering. The first sacrificial layer 118A and the second sacrificial layer 119A are formed at a temperature lower than the heat-resistant temperature limit of the EL layer (typically, 200°C or lower, preferably 100°C or lower, and more preferably 80°C or lower).

[0260] It is preferable to use a film that can be removed by wet etching for the first sacrificial layer 118A and the second sacrificial layer 119A. By using wet etching, damage to the first layer 113A during processing of the first sacrificial layer 118A and the second sacrificial layer 119A can be reduced compared to when dry etching is used.

[0261] Furthermore, it is preferable to use a film for the first sacrificial layer 118A that has a large etching selectivity with respect to the second sacrificial layer 119A.

[0262] In the process of processing the various sacrificial layers in the manufacturing method of the display device of this embodiment, it is desirable that the layers constituting the EL layer (such as the hole injection layer, hole transport layer, light-emitting layer, and electron transport layer) are not easily processed, and that the various sacrificial layers are not easily processed in the process of processing the layers constituting the EL layer. It is desirable to select the material and processing method of the sacrificial layer and the processing method of the EL layer taking these factors into consideration.

[0263] In this embodiment, an example is shown in which the sacrificial layer is formed with a two-layer structure of a first sacrificial layer and a second sacrificial layer, but the sacrificial layer may have a single-layer structure or a stacked structure of three or more layers.

[0264] The first sacrificial layer 118A and the second sacrificial layer 119A may each be, for example, a metal film, an alloy film, a metal oxide film, a semiconductor film, or an inorganic film such as an inorganic insulating film.

[0265] The first sacrificial layer 118A and the second sacrificial layer 119A can be made of a metal material such as gold, silver, platinum, magnesium, nickel, tungsten, chromium, molybdenum, iron, cobalt, copper, palladium, titanium, aluminum, yttrium, zirconium, or tantalum, or an alloy material containing such a metal material. It is particularly preferable to use a low-melting-point material such as aluminum or silver. Using a metal material capable of blocking ultraviolet light for one or both of the first sacrificial layer 118A and the second sacrificial layer 119A can prevent the EL layer from being exposed to ultraviolet light, thereby suppressing deterioration of the EL layer, which is preferable.

[0266] Furthermore, metal oxides such as In-Ga-Zn oxide can be used for the first sacrificial layer 118A and the second sacrificial layer 119A. For example, an In-Ga-Zn oxide film can be formed as the first sacrificial layer 118A or the second sacrificial layer 119A by sputtering. Furthermore, indium oxide, In-Zn 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 also be used. Alternatively, indium tin oxide containing silicon can also be used.

[0267] Instead of the gallium, an element M (M is one or more elements selected from aluminum, silicon, boron, yttrium, copper, vanadium, beryllium, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, and magnesium) may be used.

[0268] Furthermore, the first sacrificial layer 118A and the second sacrificial layer 119A can be made of any of the various inorganic insulating films that can be used for the protective layers 131 and 132. In particular, oxide insulating films are preferable because they have higher adhesion to the EL layer than nitride insulating films. For example, inorganic insulating materials such as aluminum oxide, hafnium oxide, and silicon oxide can be used for the first sacrificial layer 118A and the second sacrificial layer 119A. For example, an aluminum oxide film can be formed as the first sacrificial layer 118A or the second sacrificial layer 119A by the ALD method. Using the ALD method is preferable because it can reduce damage to the underlying layer (particularly the EL layer, etc.).

[0269] For example, the first sacrificial layer 118A may be an inorganic insulating film (e.g., an aluminum oxide film) formed by ALD, and the second sacrificial layer 119A may be an In-Ga-Zn oxide film formed by sputtering. Alternatively, the second sacrificial layer 119A may be an aluminum film or a tungsten film.

[0270] The first sacrificial layer 118A and the second sacrificial layer 119A may be made of a material that is soluble in a solvent that is chemically stable with respect to at least the film located on the topmost side of the first layer 113A. In particular, materials that dissolve in water or alcohol are suitable for use as the first sacrificial layer 118A or the second sacrificial layer 119A. When forming a film of such a material, it is preferable to apply the material dissolved in a solvent such as water or alcohol by a wet film formation method, and then perform a heat treatment to evaporate the solvent. Performing the heat treatment under a reduced pressure atmosphere is preferable because it allows the solvent to be removed at a low temperature in a short time, thereby reducing thermal damage to the EL layer.

[0271] The first sacrificial layer 118A and the second sacrificial layer 119A may be formed using a wet film formation method such as spin coating, dipping, spray coating, inkjet, dispensing, screen printing, offset printing, doctor knife method, slit coating, roll coating, curtain coating, or knife coating.

[0272] The first sacrificial layer 118A and the second sacrificial layer 119A may be made of an organic material such as polyvinyl alcohol (PVA), polyvinyl butyral, polyvinylpyrrolidone, polyethylene glycol, polyglycerin, pullulan, water-soluble cellulose, or alcohol-soluble polyamide resin.

[0273] 10B, a resist mask 190a is formed on the second sacrificial layer 119A. The resist mask can be formed by applying a photosensitive resin (photoresist) and then performing exposure and development.

[0274] The resist mask may be made of either a positive resist material or a negative resist material.

[0275] 9A, the resist mask 190a is provided in a position that overlaps with an area that will later become the subpixel 110a. Preferably, the resist mask 190a has an island-shaped pattern for each subpixel 110a. Alternatively, the resist mask 190a may have a strip-shaped pattern for multiple subpixels 110a that are aligned in a row (aligned in the Y direction in FIG. 9A).

[0276] Note that the resist mask 190a is preferably provided also in a position overlapping with a region that will later become the connection portion 140 (see FIGS. 9A and 10B). This can prevent the region of the conductive film 111 that will later become the conductive layer 123 from being damaged during the manufacturing process of the display device.

[0277] Next, using a resist mask 190a, a portion of the second sacrificial layer 119A is removed to form the second sacrificial layer 119a (FIG. 10C). The second sacrificial layer 119a remains in the region that will later become the subpixel 110a and the region that will later become the connection portion 140.

[0278] When etching the second sacrificial layer 119A, it is preferable to use etching conditions with a high selectivity so that the first sacrificial layer 118A is not removed by the etching. Furthermore, when processing the second sacrificial layer 119A, the EL layer is not exposed, so there is a wider range of processing methods to choose from than when processing the first sacrificial layer 118A. Specifically, even when a gas containing oxygen is used as an etching gas when processing the second sacrificial layer 119A, deterioration of the EL layer can be suppressed.

[0279] Thereafter, the resist mask 190a is removed (FIG. 10C). For example, the resist mask 190a can be removed by ashing using oxygen plasma. Alternatively, the resist mask 190a may be removed by wet etching. At this time, the first sacrificial layer 118A is located on the outermost surface and the first layer 113A is not exposed, so that damage to the first layer 113A can be suppressed in the process of removing the resist mask 190a. This also broadens the range of methods for removing the resist mask 190a.

[0280] Next, as shown in FIG. 11A, the second sacrificial layer 119a is used as a hard mask to remove a portion of the first sacrificial layer 118A, thereby forming a first sacrificial layer 118a.

[0281] The first sacrificial layer 118A and the second sacrificial layer 119A can be processed by wet etching or dry etching, respectively. The first sacrificial layer 118A and the second sacrificial layer 119A are preferably processed by anisotropic etching.

[0282] Compared to the case of using dry etching, the use of wet etching can reduce damage to the first layer 113A when processing the first sacrificial layer 118A and the second sacrificial layer 119A. When using wet etching, it is preferable to use a chemical solution such as a developer, a tetramethylammonium hydroxide (TMAH) aqueous solution, diluted hydrofluoric acid, oxalic acid, phosphoric acid, acetic acid, nitric acid, or a mixture thereof.

[0283] When dry etching is used, deterioration of the first layer 113A can be suppressed by not using a gas containing oxygen as an etching gas. When dry etching is used, it is preferable to use a gas containing a noble gas (also called a rare gas) such as CF, C, F, SF, CHF, Cl, HO, BCl, or He as an etching gas.

[0284] For example, when an aluminum oxide film formed by ALD is used as the first sacrificial layer 118A, the first sacrificial layer 118A can be processed by dry etching using CHF3 and He. When an In-Ga-Zn oxide film formed by sputtering is used as the second sacrificial layer 119A, the second sacrificial layer 119A can be processed by wet etching using diluted phosphoric acid.

[0285] Next, as shown in FIG. 11B, the second sacrificial layer 119a and the first sacrificial layer 118a are used as a hard mask to remove a portion of the first layer 113A, thereby forming a first layer 113a.

[0286] 11B, in the region corresponding to the subpixel 110a, a stacked structure of the first layer 113a, the first sacrificial layer 118a, and the second sacrificial layer 119a remains on the conductive film 111. In addition, in the region corresponding to the connection portion 140, a stacked structure of the first sacrificial layer 118a and the second sacrificial layer 119a remains on the conductive film 111.

[0287] Through the above steps, the regions of the first layer 113A, the first sacrificial layer 118A, and the second sacrificial layer 119A that are not overlapped with the resist mask 190a can be removed.

[0288] Note that part of the first layer 113A may be removed using the resist mask 190a, and then the resist mask 190a may be removed.

[0289] Alternatively, the next step may be performed without removing the resist mask 190a. In this case, when processing the conductive film 111 in a later step, not only the sacrificial layer but also the resist mask can be used as a mask. Processing the conductive film 111 using at least one of the resist masks 190a, 190b, and 190c may make the processing of the conductive film 111 easier than using only the sacrificial layer as a hard mask. For example, the range of options for the processing conditions of the conductive film 111, the material of the sacrificial layer, or the material of the conductive film can be expanded.

[0290] The first layer 113A is preferably processed by anisotropic etching, particularly anisotropic dry etching, or wet etching may be used.

[0291] When dry etching is used, deterioration of the first layer 113A can be suppressed by not using a gas containing oxygen as the etching gas.

[0292] Alternatively, an etching gas containing oxygen may be used. When the etching gas contains oxygen, the etching rate can be increased. Therefore, etching can be performed under low power conditions while maintaining a sufficiently high etching rate. This can reduce damage to the first layer 113A. Furthermore, problems such as adhesion of reaction products that occur during etching can be reduced.

[0293] When dry etching is used, it is preferable to use a gas containing one or more of H2, CF4, C4F8, SF6, CHF3, Cl2, H2O, BCl3, or noble gases (also called rare gases) such as He and Ar as the etching gas. Alternatively, it is preferable to use a gas containing one or more of these and oxygen as the etching gas. Alternatively, oxygen gas may be used as the etching gas. Specifically, for example, a gas containing H2 and Ar, or a gas containing CF4 and He may be used as the etching gas. Alternatively, for example, a gas containing CF4, He, and oxygen may be used as the etching gas.

[0294] Next, as shown in FIG. 11C, a second layer 113B is formed on the second sacrificial layer 119a and the conductive film 111, a first sacrificial layer 118B is formed on the second layer 113B, and a second sacrificial layer 119B is formed on the first sacrificial layer 118B.

[0295] As shown in FIG. 11C, in the cross section taken along line Y1-Y2, the end of second layer 113B on the connection section 140 side is located more inward (toward the display section) than the end of first sacrificial layer 118B.

[0296] The second layer 113B is a layer that will later become the second layer 113b. The second layer 113b emits light of a different color from the first layer 113a. The configuration, materials, etc. that can be applied to the second layer 113b are the same as those of the first layer 113a. The second layer 113B can be formed using the same method as the first layer 113A.

[0297] The first sacrificial layer 118B can be formed using a material that can be applied to the first sacrificial layer 118A. The second sacrificial layer 119B can be formed using a material that can be applied to the second sacrificial layer 119A.

[0298] Next, as shown in FIG. 11C, a resist mask 190b is formed on the second sacrificial layer 119B.

[0299] 9B, the resist mask 190b is provided in a position that overlaps with an area that will later become the sub-pixel 110b. Preferably, the resist mask 190b has an island-shaped pattern for each sub-pixel 110b. Alternatively, the resist mask 190b may have a strip-shaped pattern for multiple sub-pixels 110b that are arranged in a row.

[0300] The resist mask 190b may also be provided at a position overlapping the region that will later become the connection portion 140.

[0301] Next, using a resist mask 190b, a portion of the second sacrificial layer 119B is removed to form a second sacrificial layer 119b, which remains in the region that will later become the subpixel 110b.

[0302] Thereafter, the resist mask 190b is removed, and then, using the second sacrificial layer 119b as a hard mask, a portion of the first sacrificial layer 118B is removed to form the first sacrificial layer 118b.

[0303] Then, as shown in FIG. 12A, second sacrificial layer 119b and first sacrificial layer 118b are used as a hard mask to remove a portion of second layer 113B, thereby forming second layer 113b.

[0304] 12A, in the region corresponding to the subpixel 110b, a stacked structure of the second layer 113b, the first sacrificial layer 118b, and the second sacrificial layer 119b remains on the conductive film 111. In addition, in the region corresponding to the connection portion 140, a stacked structure of the first sacrificial layer 118a and the second sacrificial layer 119a remains on the conductive film 111.

[0305] Through the above steps, it is possible to remove the regions of the second layer 113B, the first sacrificial layer 118B, and the second sacrificial layer 119B that are not overlapped with the resist mask 190b. These layers can be processed using a method that can be applied to processing the first layer 113A, the first sacrificial layer 118A, and the second sacrificial layer 119A.

[0306] Next, as shown in FIG. 12B, a third layer 113C is formed on the second sacrificial layer 119a, the second sacrificial layer 119b, and the conductive film 111, a first sacrificial layer 118C is formed on the third layer 113C, and a second sacrificial layer 119C is formed on the first sacrificial layer 118C.

[0307] As shown in FIG. 12B, in the cross section taken along line Y1-Y2, the end of third layer 113C on the connection section 140 side is located more inward (toward the display section) than the end of first sacrificial layer 118C.

[0308] The third layer 113C is a layer that will later become the third layer 113c. The third layer 113c emits light of a different color from the first layer 113a and the second layer 113b. The configuration, materials, etc. that can be applied to the third layer 113c are the same as those of the first layer 113a. The third layer 113C can be formed using a method similar to that for the first layer 113A.

[0309] The first sacrificial layer 118C can be formed using a material that can be applied to the first sacrificial layer 118A. The second sacrificial layer 119C can be formed using a material that can be applied to the second sacrificial layer 119A.

[0310] Next, as shown in FIG. 12B, a resist mask 190c is formed on the second sacrificial layer 119C.

[0311] 9C, the resist mask 190c is provided in a position that overlaps with an area that will later become the subpixel 110c. Preferably, the resist mask 190c has an island-shaped pattern for each subpixel 110c. Alternatively, the resist mask 190c may have a strip-shaped pattern for multiple subpixels 110c that are arranged in a row.

[0312] The resist mask 190c may also be provided at a position that overlaps with the region that will later become the connection portion 140.

[0313] Next, using a resist mask 190c, a portion of the second sacrificial layer 119C is removed to form a second sacrificial layer 119c, which remains in the region that will later become the subpixel 110c.

[0314] Thereafter, the resist mask 190c is removed, and then, using the second sacrificial layer 119c as a hard mask, a portion of the first sacrificial layer 118C is removed to form the first sacrificial layer 118c.

[0315] Then, as shown in FIG. 12C, the second sacrificial layer 119c and the first sacrificial layer 118c are used as a hard mask to remove a portion of the third layer 113C, thereby forming the third layer 113c.

[0316] 12C, in the region corresponding to the subpixel 110c, a stacked structure of the third layer 113c, the first sacrificial layer 118c, and the second sacrificial layer 119c remains on the conductive film 111. In addition, in the region corresponding to the connection portion 140, a stacked structure of the first sacrificial layer 118a and the second sacrificial layer 119a remains on the conductive film 111.

[0317] Through the above steps, it is possible to remove the regions of the third layer 113C, the first sacrificial layer 118C, and the second sacrificial layer 119C that are not overlapped with the resist mask 190c. These layers can be processed using a method that is applicable to processing the first layer 113A, the first sacrificial layer 118A, and the second sacrificial layer 119A.

[0318] The side surfaces of the first layer 113a, the second layer 113b, and the third layer 113c are preferably perpendicular or approximately perpendicular to the surface on which they are formed. For example, the angle between the surface on which they are formed and these side surfaces is preferably 60 degrees or more and 90 degrees or less.

[0319] Next, as shown in FIG. 13A, the conductive film 111 is processed using the first sacrificial layers 118a, 118b, and 118c and the second sacrificial layers 119a, 119b, and 119c as hard masks to form pixel electrodes 111a, 111b, and 111c and a conductive layer 123.

[0320] When the conductive film 111 is processed, a part of the transistor-including layer 101 (specifically, the insulating layer located at the outermost surface) may be processed to form a recess. In the following description, a case where a recess is provided in the transistor-including layer 101 will be described as an example, but the recess is not necessarily provided.

[0321] Here, in order to form the conductive layer 123, it is preferable that any one of the first sacrificial layers 118a, 118b, and 118c and any one of the second sacrificial layers 119a, 119b, and 119c are provided in the connection portion 140. Two or all of the first sacrificial layers 118a, 118b, and 118c and two or all of the second sacrificial layers 119a, 119b, and 119c may be provided in the connection portion 140. By providing the sacrificial layers in the connection portion 140, a region of the conductive film 111 that will become the conductive layer 123 can be prevented from being damaged during the manufacturing process of the display device. Therefore, it is preferable to form the first sacrificial layer 118a and the second sacrificial layer 119a, which are manufactured earliest.

[0322] The conductive film 111 can be processed by a wet etching method or a dry etching method. The conductive film 111 is preferably processed by anisotropic etching.

[0323] Next, as shown in FIG. 13B, an insulating film 125A is formed to cover the pixel electrodes 111a, 111b, and 111c, the conductive layer 123, the first layer 113a, the second layer 113b, the third layer 113c, the first sacrificial layers 118a, 118b, and 118c, and the second sacrificial layers 119a, 119b, and 119c.

[0324] The insulating film 125A can be, for example, an inorganic insulating film such as an oxide insulating film, a nitride insulating film, an oxynitride insulating film, or a nitride oxide insulating film. Examples of oxide insulating films include a silicon oxide film, an aluminum oxide film, a magnesium oxide film, a gallium oxide film, a germanium oxide film, an yttrium oxide film, a zirconium oxide film, a lanthanum oxide film, a neodymium oxide film, a hafnium oxide film, and a tantalum oxide film. Examples of nitride insulating films include a silicon nitride film and an aluminum nitride film. Examples of oxynitride insulating films include a silicon oxynitride film and an aluminum oxynitride film. Examples of nitride oxide insulating films include a silicon nitride oxide film and an aluminum nitride oxide film. Alternatively, a metal oxide film such as an indium gallium zinc oxide film may be used.

[0325] The insulating film 125A preferably functions as a barrier insulating film against at least one of water and oxygen, or has a function of suppressing the diffusion of at least one of water and oxygen, or has a function of capturing or fixing (also called gettering) at least one of water and oxygen.

[0326] In this specification and the like, a barrier insulating film refers to an insulating film having barrier properties. In addition, in this specification and the like, the barrier properties refer to a function of suppressing the diffusion of a corresponding substance (also referred to as low permeability), or a function of capturing or fixing (also referred to as gettering) a corresponding substance.

[0327] The insulating film 125A has the above-mentioned barrier insulating film function or gettering function, which makes it possible to suppress the intrusion of impurities (typically water or oxygen) that can diffuse into each light-emitting device from the outside. With this configuration, it is possible to provide a display device with excellent reliability.

[0328] Next, as shown in FIG. 13C, an insulating film 127A is formed on the insulating film 125A.

[0329] 9D, the insulating film 127A is preferably formed so as to have an opening at a position overlapping the conductive layer 123 (connection portion 140). The insulating film 127A can be patterned by, for example, applying a photosensitive resin and then performing exposure and development.

[0330] As shown in FIG. 16A, the insulating film 127A may be formed so as to have openings at positions overlapping with the pixel electrodes 111a, 111b, and 111c.

[0331] The insulating film 127A can be made of an organic material. Examples of organic materials include acrylic resin, polyimide resin, epoxy resin, imide resin, polyamide resin, polyimideamide resin, silicone resin, siloxane resin, benzocyclobutene-based resin, phenol resin, and precursors of these resins. The insulating film 127A can also be made of an organic material such as polyvinyl alcohol (PVA), polyvinyl butyral, polyvinylpyrrolidone, polyethylene glycol, polyglycerin, pullulan, water-soluble cellulose, or alcohol-soluble polyamide resin. The insulating film 127A can also be made of a photosensitive resin. A photoresist can be used as the photosensitive resin. The photosensitive resin can be a positive-type material or a negative-type material.

[0332] The method for forming the insulating film 127A is not particularly limited, and it can be formed using a wet film formation method such as spin coating, dipping, spray coating, inkjet, dispensing, screen printing, offset printing, doctor knife method, slit coating, roll coating, curtain coating, knife coating, etc. In particular, it is preferable to form the insulating film 127A by spin coating.

[0333] The insulating films 125A and 127A are preferably formed by a method that causes less damage to the EL layer. In particular, since the insulating film 125A is formed in contact with the side surface of the EL layer, it is preferably formed by a method that causes less damage to the EL layer than the insulating film 127A. Furthermore, the insulating films 125A and 127A are each formed at a temperature lower than the heat resistance temperature of the EL layer (typically 200°C or lower, preferably 100°C or lower, and more preferably 80°C or lower). For example, an aluminum oxide film can be formed as the insulating film 125A by the ALD method. The ALD method is preferable because it can reduce film damage and form a film with high coverage.

[0334] Next, as shown in FIG. 14A , insulating layers 125 and 127 are formed by processing insulating films 125A and 127A. Insulating layer 127 is formed so as to contact the side surfaces of insulating layer 125 and the upper surfaces of the recesses. Insulating layer 125 (and further insulating layer 127) are provided so as to cover the side surfaces of pixel electrodes 111a, 111b, and 111c. This prevents a film (a film constituting an EL layer or a common electrode) to be formed later from contacting the pixel electrodes 111a, 111b, and 111c, which would otherwise cause a short circuit in the light-emitting device. Furthermore, insulating layer 125 and insulating layer 127 are preferably provided so as to cover the side surfaces of first layer 113a, second layer 113b, and third layer 113c. This prevents a film to be formed later from contacting the side surfaces of these layers, thereby preventing a short circuit in the light-emitting device. Furthermore, damage to the first layer 113a, the second layer 113b, and the third layer 113c in subsequent steps can be suppressed.

[0335] In particular, it is preferable to provide a recess in a part of the layer 101 including the transistor (specifically, in the insulating layer located on the outermost surface), because this makes it possible to cover the entire side surfaces of the pixel electrodes 111a, 111b, and 111c with the insulating layer 125 and the insulating layer 127.

[0336] The insulating film 125A is preferably processed by dry etching. The insulating film 125A is preferably processed by anisotropic etching. The insulating film 125A can be processed using an etching gas that can be used to process the first sacrificial layer 118A and the second sacrificial layer 119A.

[0337] The insulating film 127A is preferably processed by ashing using oxygen plasma, for example.

[0338] Next, as shown in FIG. 14B, the first sacrificial layers 118a, 118b, and 118c and the second sacrificial layers 119a, 119b, and 119c are removed. As a result, the first layer 113a is exposed on the pixel electrode 111a, the second layer 113b is exposed on the pixel electrode 111b, the third layer 113c is exposed on the pixel electrode 111c, and the conductive layer 123 is exposed in the connection portion 140. Note that portions of the first sacrificial layers 118a, 118b, and 118c and the second sacrificial layers 119a, 119b, and 119c may remain. For example, in the connection portion 140, etc., a region of the sacrificial layer overlapping with the insulating layer 125 may remain (see FIG. 14B).

[0339] The height of the upper surface of insulating layer 125 and the height of the upper surface of insulating layer 127 preferably match or approximately match the height of the upper surface of at least one of first layer 113a, second layer 113b, and third layer 113c. The upper surface of insulating layer 127 preferably has a flat shape, and may have protrusions or recesses.

[0340] The sacrificial layer removal step can be performed using the same method as the sacrificial layer processing step. In particular, by using a wet etching method, damage to the first layer 113a, the second layer 113b, and the third layer 113c can be reduced compared to when a dry etching method is used when removing the first sacrificial layer and the second sacrificial layer.

[0341] The first sacrificial layer and the second sacrificial layer may be removed in separate steps or in the same step.

[0342] Alternatively, either or both of the first and second sacrificial layers may be removed by dissolving them in a solvent such as water or alcohol, such as ethyl alcohol, methyl alcohol, isopropyl alcohol (IPA), or glycerin.

[0343] After removing the first and second sacrificial layers, a drying treatment may be performed to remove water contained in the EL layer and water adsorbed on the surface of the EL layer. For example, a heat treatment can be performed in an inert gas atmosphere or a reduced pressure atmosphere. The heat treatment can be performed at a substrate temperature of 50°C or higher and 200°C or lower, preferably 60°C or higher and 150°C or lower, and more preferably 70°C or higher and 120°C or lower. A reduced pressure atmosphere is preferred because it allows drying at a lower temperature.

[0344] Next, as shown in Fig. 14C, a fifth layer 114 is formed to cover the insulating layers 125 and 127, the first layer 113a, the second layer 113b, and the third layer 113c. As shown in Fig. 14C, in the cross-sectional view between Y1 and Y2, the end of the fifth layer 114 on the connection section 140 side is located more inward (toward the display section) than the connection section 140, and the conductive layer 123 remains exposed even after the fifth layer 114 is formed. Note that depending on the level of conductivity of the fifth layer 114, the fifth layer 114 may be provided at the connection section 140.

[0345] The materials that can be used for the fifth layer 114 are as described above. The fifth layer 114 can be formed by a method such as a vapor deposition method (including a vacuum deposition method), a transfer method, a printing method, an inkjet method, or a coating method. The fifth layer 114 may also be formed using a premixed material.

[0346] If the insulating layers 125 and 127 were not provided, any of the pixel electrodes 111a, 111b, and 111c might come into contact with the fifth layer 114. Contact between these layers might cause a short circuit in the light-emitting device, especially if the fifth layer 114 has high conductivity. However, in the display device of one embodiment of the present invention, the insulating layers 125 and 127 cover the side surfaces of the first layer 113a, the second layer 113b, the third layer 113c, and the pixel electrodes 111a, 111b, and 111c. This prevents the highly conductive fifth layer 114 from coming into contact with these layers, thereby preventing a short circuit in the light-emitting device. This improves the reliability of the light-emitting device.

[0347] Then, as shown in FIG. 14C, the common electrode 115 is formed on the fifth layer 114 and the conductive layer 123.

[0348] The materials that can be used for the common electrode 115 are as described above. The common electrode 115 can be formed by, for example, sputtering or vacuum deposition. Alternatively, a film formed by deposition and a film formed by sputtering may be stacked.

[0349] Thereafter, a protective layer 131 is formed on the common electrode 115, and a protective layer 132 is formed on the protective layer 131. Furthermore, by using a resin layer 122, a substrate 120 is bonded onto the protective layer 132, whereby the display device 100 shown in FIG. 1B can be manufactured.

[0350] The materials and film formation methods that can be used for the protective layers 131 and 132 are as described above. Film formation methods for the protective layers 131 and 132 include vacuum deposition, sputtering, CVD, and ALD. The protective layers 131 and 132 may be films formed using different film formation methods. Furthermore, the protective layers 131 and 132 may each have a single-layer structure or a multilayer structure.

[0351] A mask for defining a film formation area may be used when forming the common electrode 115. Alternatively, without using the mask for forming the common electrode 115, the process of processing the common electrode 115 shown in Figures 15A and 15B may be performed after the process shown in Figure 14C, and then the process of forming the protective layer 131 may be performed.

[0352] As shown in Fig. 15A and Fig. 9E, a resist mask 190d is formed on the common electrode 115. There is a portion at the end on the Y2 side in Fig. 15A where the resist mask 190d is not provided. As shown in Fig. 9E, the resist mask 190d is provided in a region overlapping each sub-pixel and the connection section 140. In other words, the region where the resist mask 190d is not provided is located outside the connection section 140 (on the opposite side from the display section).

[0353] 15B, a resist mask 190d is used to remove a portion of the common electrode 115. In this manner, the common electrode 115 can be processed.

[0354] When the resist mask 190d is used, five photomasks are used in the series of manufacturing steps because the resist masks 190a, 190b, 190c, and 190d and the insulating film 127A are processed. When the resist mask 190d is not used, four photomasks are used in the series of manufacturing steps because the resist masks 190a, 190b, and 190c and the insulating film 127A are processed. In addition, a mask for defining a deposition area is used for forming the common electrode 115. The manufacturing method of the display device of one embodiment of the present invention does not require the use of a metal mask with a high-resolution pattern for forming an island-shaped EL layer, a mask for forming an island-shaped pixel electrode, and a mask for forming an insulating layer that covers an edge of the pixel electrode, thereby reducing the number of masks and the cost.

[0355] 16B, the fifth layer 114 may be omitted, and a common electrode 115 may be formed to cover the insulating layers 125 and 127, the first layer 113a, the second layer 113b, and the third layer 113c. In other words, all layers constituting the EL layer may be formed separately for each light-emitting device that emits light of a different color. In this case, the EL layer of each light-emitting device is formed in an island shape.

[0356] Here, contact between any of the pixel electrodes 111a, 111b, and 111c and the common electrode 115 may cause a short circuit in the light-emitting device. However, in the display device of one embodiment of the present invention, the insulating layers 125 and 127 cover the side surfaces of the first layer 113a, the second layer 113b, and the third layer 113c and the pixel electrodes 111a, 111b, and 111c, thereby preventing the common electrode 115 from contacting these layers and preventing a short circuit in the light-emitting device. This improves the reliability of the light-emitting device.

[0357] Furthermore, as shown in FIG. 16C, if a portion of the transistor-containing layer 101 (specifically, the insulating layer located on the outermost surface) is not processed when processing the conductive film 111, a recess may not be formed in the transistor-containing layer 101.

[0358] 16D, the insulating layer 125 does not have to be provided. In this case, it is preferable to use an organic material that causes less damage to the first layer 113a, the second layer 113b, and the third layer 113c for the insulating layer 127. For example, it is preferable to use an organic material such as polyvinyl alcohol (PVA), polyvinyl butyral, polyvinylpyrrolidone, polyethylene glycol, polyglycerin, pullulan, water-soluble cellulose, or alcohol-soluble polyamide resin for the insulating layer 127.

[0359] When the fifth layer 114 is provided in the connection section 140, the conductive layer 123 and the common electrode 115 are electrically connected via the fifth layer 114 as shown in FIG. 16E.

[0360] 17A to 17F show the cross-sectional structure of a region 139 including the insulating layer 127 and its surroundings.

[0361] FIG. 17A shows an example in which the first layer 113a and the second layer 113b have different thicknesses. The height of the top surface of the insulating layer 125 on the first layer 113a side is the same as or approximately the same as the top surface of the first layer 113a, and the height of the top surface of the second layer 113b on the second layer 113b side is the same as or approximately the same as the top surface of the second layer 113b. The top surface of the insulating layer 127 has a gentle slope, with the first layer 113a side being higher and the second layer 113b side being lower. In this way, the heights of the insulating layers 125 and 127 are preferably the same as the top surfaces of the adjacent EL layers. Alternatively, the top surface of the insulating layer 127 may have a flat portion that is the same as the top surface of one of the adjacent EL layers.

[0362] 17B, ​​the upper surface of insulating layer 127 has a region that is higher than the upper surface of first layer 113a and the upper surface of second layer 113b. The upper surface of insulating layer 127 also has a shape that gently bulges outward in a convex shape toward the center.

[0363] 17C , insulating layer 127 has a region higher than the upper surface of first layer 113a and the upper surface of second layer 113b. Furthermore, in region 139, display device 100 has at least one of first sacrificial layer 118a and second sacrificial layer 119a. Furthermore, in region 139, display device 100 has at least one of first sacrificial layer 118b and second sacrificial layer 119b. Insulating layer 125 is located on the sacrificial layer, and insulating layer 127 is located on insulating layer 125. Insulating layer 127 has a portion overlapping with first layer 113a via the sacrificial layer and a portion overlapping with second layer 113b via the sacrificial layer.

[0364] 17D, the upper surface of insulating layer 127 has an area that is lower than the upper surfaces of first layer 113a and second layer 113b. The upper surface of insulating layer 127 also has a gently sloping shape that is concave toward the center.

[0365] 17E, the upper surface of insulating layer 125 has a region that is higher than the upper surface of first layer 113a and the upper surface of second layer 113b. That is, insulating layer 125 protrudes from the surface on which fifth layer 114 is to be formed, forming a convex portion.

[0366] For example, when insulating layer 125 is formed so as to be aligned or approximately aligned with the height of the sacrificial layer, insulating layer 125 may be formed in a protruding shape as shown in FIG. 17E.

[0367] 17F, the upper surface of insulating layer 125 has an area lower than the upper surfaces of first layer 113a and second layer 113b. That is, insulating layer 125 forms a recess on the surface on which fifth layer 114 is to be formed.

[0368] In this way, the insulating layer 125 and the insulating layer 127 can be applied in various shapes.

[0369] As described above, in the manufacturing method of the display device of this embodiment, the island-shaped EL layer is formed by forming the EL layer on the entire surface and then processing it, rather than by using a fine metal mask, so that the island-shaped EL layer can be formed with a uniform thickness, and a high-definition display device or a display device with a high aperture ratio can be realized.

[0370] The first, second, and third layers that make up the light-emitting device for each color are formed in separate processes. This allows each EL layer to be fabricated with a configuration (material, film thickness, etc.) that is suitable for the light-emitting device for that color. This allows for the fabrication of light-emitting devices with excellent characteristics.

[0371] A display device according to one embodiment of the present invention includes an insulating layer covering each side surface of a pixel electrode, a light-emitting layer, and a carrier transport layer. In a manufacturing process of the display device, the EL layer is processed while the light-emitting layer and the carrier transport layer are stacked. Therefore, the display device has a structure in which damage to the light-emitting layer is reduced. Furthermore, the insulating layer prevents the pixel electrode from contacting the carrier injection layer or the common electrode, thereby preventing a short circuit of the light-emitting device.

[0372] This embodiment mode can be combined with other embodiment modes as appropriate. In addition, in this specification, when a plurality of configuration examples are shown in one embodiment mode, the configuration examples can be combined as appropriate.

[0373] (Embodiment 2) In this embodiment, structural examples of a light-emitting device that can be applied to a display device of one embodiment of the present invention will be described with reference to FIGS.

[0374] The display device 500 shown in FIGS. 18A to 18C includes a light emitting device 550R that emits red light, a light emitting device 550G that emits green light, and a light emitting device 550B that emits blue light.

[0375] 18A and 18B includes a light-emitting unit 512R_1 between a pair of electrodes (electrode 501 and electrode 502). Similarly, a light-emitting device 550G includes a light-emitting unit 512G_1, and a light-emitting device 550B includes a light-emitting unit 512B_1.

[0376] That is, each of the light emitting devices 550R, 550G, and 550B shown in FIGS. 18A and 18B is a single-structure light emitting device having one light emitting unit.

[0377] 18C has a configuration in which two light-emitting units (light-emitting unit 512R_1 and light-emitting unit 512R_2) are stacked between a pair of electrodes (electrode 501 and electrode 502) via a charge generation layer 531. Similarly, light-emitting device 550G has light-emitting units 512G_1 and 512G_2, and light-emitting device 550B has light-emitting units 512B_1 and 512B_2.

[0378] That is, each of the light-emitting devices 550R, 550G, and 550B shown in FIG. 18C is a light-emitting device having a tandem structure and two light-emitting units.

[0379] A configuration in which multiple light-emitting units are connected in series via a charge generation layer 531, such as light-emitting device 550R, light-emitting device 550G, and light-emitting device 550B shown in FIG. 18C, is referred to herein as a tandem structure. On the other hand, a configuration in which one light-emitting unit is located between a pair of electrodes, such as light-emitting devices 550R, 550G, and 550B shown in FIGS. 18A and 18B, is referred to as a single structure. Although the term "tandem structure" is used herein, this is not intended to be limiting. For example, the tandem structure may also be referred to as a "stack structure." The tandem structure allows for a light-emitting device capable of emitting light with high brightness. Furthermore, the tandem structure can reduce the current required to achieve the same brightness compared to a single structure, thereby improving reliability.

[0380] Furthermore, a structure in which a separate light-emitting layer is formed for each light-emitting device, such as the display device 500 shown in FIGS. 18A to 18C, is sometimes called an SBS (Side By Side) structure.

[0381] The display device 500 shown in FIG. 18C has light-emitting devices with a tandem structure and can be considered to have an SBS structure. Therefore, it can combine the advantages of both a tandem structure and an SBS structure. The display device 500 shown in FIG. 18C may also be referred to as a two-tier tandem structure because the light-emitting units are arranged in two series. The two-tier tandem structure of the light-emitting device 550R shown in FIG. 18C includes a first light-emitting unit having a red light-emitting layer and a second light-emitting unit having a red light-emitting layer stacked on top of it. Similarly, the two-tier tandem structure of the light-emitting device 550G shown in FIG. 18C includes a first light-emitting unit having a green light-emitting layer and a second light-emitting unit having a green light-emitting layer stacked on top of it. The two-tier tandem structure of the light-emitting device 550B includes a first light-emitting unit having a blue light-emitting layer and a second light-emitting unit having a blue light-emitting layer stacked on top of it.

[0382] An electrode 501 functions as a pixel electrode and is provided for each light-emitting device, and an electrode 502 functions as a common electrode and is provided in common to a plurality of light-emitting devices.

[0383] The light-emitting unit has at least one light-emitting layer, and the number of light-emitting layers that the light-emitting unit has is not limited, and may be one, two, three, four or more.

[0384] The light-emitting unit 512R_1 has a layer 521, a layer 522, a light-emitting layer 523R, a layer 524, etc. FIG. 18A shows an example in which the light-emitting unit 512R_1 has a layer 525, and FIG. 18B shows an example in which the light-emitting unit 512R_1 does not have the layer 525, and the layer 525 is provided in common among the light-emitting devices. In this case, the layer 525 can be called a common layer. In this way, by providing one or more common layers among the multiple light-emitting devices, the manufacturing process can be simplified, and therefore the manufacturing cost can be reduced.

[0385] The light-emitting unit 512R_2 includes a layer 522, a light-emitting layer 523R, a layer 524, etc. Although Fig. 18C shows an example in which the layer 525 is provided as a common layer, the layer 525 may be provided for each light-emitting device. In other words, the layer 525 may be included in the light-emitting unit 512R_2.

[0386] The layer 521 includes, for example, a layer containing a substance with a high hole-injecting property (hole-injecting layer). The layer 522 includes, for example, a layer containing a substance with a high hole-transporting property (hole-transporting layer). The layer 524 includes, for example, a layer containing a substance with a high electron-transporting property (electron-transporting layer). The layer 525 includes, for example, a layer containing a substance with a high electron-injecting property (electron-injecting layer).

[0387] Alternatively, a structure in which the layer 521 has an electron-injecting layer, the layer 522 has an electron-transporting layer, the layer 524 has a hole-transporting layer, and the layer 525 has a hole-injecting layer may be used.

[0388] The layer 522, the light-emitting layer 523R, and the layer 524 may have the same configuration (material, film thickness, etc.) between the light-emitting unit 512R_1 and the light-emitting unit 512R_2, or may have different configurations.

[0389] 18A and other figures, the layer 521 and the layer 522 are shown separately, but this is not limiting. For example, when the layer 521 has a function as both a hole injection layer and a hole transport layer, or when the layer 521 has a function as both an electron injection layer and an electron transport layer, the layer 522 may be omitted.

[0390] The charge generation layer 531 has a function of injecting electrons into one of the light-emitting unit 512R_1 and the light-emitting unit 512R_2 and injecting holes into the other when a voltage is applied between the electrode 501 and the electrode 502. The charge generation layer 531 has at least a charge generation region.

[0391] Light-emitting layer 523R of light-emitting device 550R contains a light-emitting material that emits red light, light-emitting layer 523G of light-emitting device 550G contains a light-emitting material that emits green light, and light-emitting layer 523B of light-emitting device 550B contains a light-emitting material that emits blue light. Light-emitting device 550G and light-emitting device 550B have a configuration in which light-emitting layer 523R of light-emitting device 550R is replaced with light-emitting layer 523G and light-emitting layer 523B, respectively, and are otherwise similar in configuration to light-emitting device 550R.

[0392] The layers 521, 522, 524, and 525 may have the same configuration (material, film thickness, etc.) for each color light-emitting device, or may have different configurations.

[0393] 18A and 18B, the light-emitting unit 512R_1, the light-emitting unit 512G_1, and the light-emitting unit 512B_1 can be formed as island-shaped layers. That is, the layer 113 shown in FIGS. 18A and 18B corresponds to the first layer 113a, the second layer 113b, or the third layer 113c shown in FIG. 1B, etc.

[0394] In Figure 18C, the light-emitting unit 512R_1, the charge generation layer 531, and the light-emitting unit 512R_2 can be formed as island-shaped layers. The light-emitting unit 512G_1, the charge generation layer 531, and the light-emitting unit 512G_2 can also be formed as island-shaped layers. The light-emitting unit 512B_1, the charge generation layer 531, and the light-emitting unit 512B_2 can also be formed as island-shaped layers. That is, the layer 113 shown in Figure 18C corresponds to the first layer 113a, the second layer 113b, or the third layer 113c shown in Figure 1B, etc.

[0395] In Figures 18B and 18C, layer 525 corresponds to fifth layer 114 shown in Figure 1B.

[0396] 18C , the light-emitting layer 523R of the light-emitting unit 512R_1 may include a phosphorescent material, the light-emitting layer 523R of the light-emitting unit 512R_2 may include a phosphorescent material, the light-emitting layer 523G of the light-emitting unit 512G_1 may include a fluorescent material, the light-emitting layer 523G of the light-emitting unit 512G_2 may include a fluorescent material, the light-emitting layer 523B of the light-emitting unit 512B_1 may include a fluorescent material, and the light-emitting layer 523B of the light-emitting unit 512B_2 may include a fluorescent material.

[0397] Alternatively, in the display device 500 shown in FIG. 18C, the light-emitting layer 523R of the light-emitting unit 512R_1 can have a phosphorescent material, the light-emitting layer 523R of the light-emitting unit 512R_2 can have a phosphorescent material, the light-emitting layer 523G of the light-emitting unit 512G_1 can have a phosphorescent material, the light-emitting layer 523G of the light-emitting unit 512G_2 can have a phosphorescent material, the light-emitting layer 523B of the light-emitting unit 512B_1 can have a fluorescent material, and the light-emitting layer 523B of the light-emitting unit 512B_2 can have a fluorescent material.

[0398] Note that the display device of one embodiment of the present invention may have a structure in which all light-emitting layers are formed using a fluorescent material or a structure in which all light-emitting layers are formed using a phosphorescent material.

[0399] 18C , the light-emitting layer 523R of the light-emitting unit 512R_1 may be made of a phosphorescent material and the light-emitting layer 523R of the light-emitting unit 512R_2 may be made of a fluorescent material, or the light-emitting layer 523R of the light-emitting unit 512R_1 may be made of a fluorescent material and the light-emitting layer 523R of the light-emitting unit 512R_2 may be made of a phosphorescent material, that is, the light-emitting layers of the first and second stages may be made of different materials. Note that, although the description here has been made explicitly about the light-emitting units 512R_1 and 512R_2, the same configurations can also be applied to the light-emitting units 512G_1 and 512G_2, and the light-emitting units 512B_1 and 512B_2.

[0400] 19A and 19B includes a plurality of light-emitting devices 550W that emit white light. A colored layer 545R that transmits red light, a colored layer 545G that transmits green light, or a colored layer 545B that transmits blue light is provided on each light-emitting device 550W. Preferably, the colored layers 545R, 545G, and 545B are provided on the light-emitting device 550W via a protective layer 540.

[0401] A light-emitting device 550W shown in FIG. 19A has a light-emitting unit 512W between a pair of electrodes (electrode 501 and electrode 502).

[0402] That is, the light emitting device 550W shown in FIG. 19A is a light emitting device with a single structure having one light emitting unit.

[0403] The light-emitting unit 512W includes a layer 521, a layer 522, a light-emitting layer 523Q_1, a light-emitting layer 523Q_2, a light-emitting layer 523Q_3, a layer 524, etc. The light-emitting device 550W includes a layer 525 between the light-emitting unit 512W and the electrode 502. The layer 525 can also be considered as part of the light-emitting unit 512W.

[0404] 19A, by selecting light-emitting layers such that the light emitted from the light-emitting layer 523Q_1, the light-emitting layer 523Q_2, and the light-emitting layer 523Q_3 has a complementary color relationship, white light can be emitted from the light-emitting device 550W. Note that, although an example in which the light-emitting unit 512W has three light-emitting layers is shown here, the number of light-emitting layers is not limited, and may be, for example, two.

[0405] 19A has a configuration in which the light-emitting layer 523R of the light-emitting device 550R shown in FIG. 18B is replaced with light-emitting layers 523Q_1 to 523Q_3, and the other configurations are the same as those of the light-emitting device 550R.

[0406] A light-emitting device 550W shown in FIG. 19B has a configuration in which two light-emitting units (light-emitting unit 512Q_1 and light-emitting unit 512Q_2) are stacked between a pair of electrodes (electrode 501 and electrode 502) with a charge generation layer 531 interposed therebetween.

[0407] The light-emitting unit 512Q_1 includes a layer 521, a layer 522, a light-emitting layer 523Q_1, a layer 524, etc. The light-emitting unit 512Q_2 includes a layer 522, a light-emitting layer 523Q_2, a layer 524, etc. The light-emitting device 550W also includes a layer 525 between the light-emitting unit 512Q_2 and the electrode 502. The layer 525 can also be considered as part of the light-emitting unit 512Q_2.

[0408] In the light-emitting device 550W shown in FIG. 19B, white light can be obtained from the light-emitting device 550W by selecting light-emitting layers such that the light emitted by the light-emitting layers 523Q_1 and 523Q_2 have a complementary color relationship. Note that, although an example is shown here in which the light-emitting units 512Q_1 and 512Q_2 each have one light-emitting layer, the number of light-emitting layers in each light-emitting unit is not important. For example, the light-emitting units 512Q_1 and 512Q_2 may have different numbers of light-emitting layers. For example, one light-emitting unit may have two light-emitting layers, and the other light-emitting unit may have one light-emitting layer.

[0409] 19B has a configuration in which the light emitting layer 523R of the light emitting device 550R shown in FIG. 18C is replaced with a light emitting layer 523Q_1 and the like, and the other configuration is the same as that of the light emitting device 550R.

[0410] The display device 500 shown in Figures 20 to 22 has a light emitting device 550R that emits red light, a light emitting device 550G that emits green light, a light emitting device 550B that emits blue light, and a light emitting device 550W that emits white light.

[0411] The display device shown in Figures 20A and 20B is an example in which a light-emitting device 550W that emits white light is provided in addition to the light-emitting devices 550R, 550G, and 550B shown in Figure 18B. The display device shown in Figure 21A is an example in which a light-emitting device 550W that emits white light is provided in addition to the light-emitting devices 550R, 550G, and 550B shown in Figure 18C.

[0412] The light-emitting device 550W shown in Figures 20A and 21A has a configuration in which two light-emitting units (light-emitting unit 512Q_1 and light-emitting unit 512Q_2) are stacked between a pair of electrodes (electrode 501 and electrode 502) with a charge generation layer 531 interposed therebetween.

[0413] The light-emitting device 550W shown in FIG. 20B has a configuration in which three light-emitting units (light-emitting unit 512Q_1, light-emitting unit 512Q_2, and light-emitting unit 512Q_3) are stacked between a pair of electrodes (electrode 501 and electrode 502) with a charge generation layer 531 interposed therebetween.

[0414] The light-emitting unit 512Q_1 includes a layer 521, a layer 522, a light-emitting layer 523Q_1, a layer 524, etc. The light-emitting unit 512Q_2 includes a layer 522, a light-emitting layer 523Q_2, a layer 524, etc. The light-emitting unit 512Q_3 includes a layer 522, a light-emitting layer 523Q_3, a layer 524, etc.

[0415] In the light emitting device 550W shown in FIGS. 20A and 21A, white light can be obtained from the light emitting device 550W by selecting light emitting layers 523Q_1 and 523Q_2 such that the light emitted from these layers has a complementary color relationship.

[0416] In the light-emitting device 550W shown in FIG. 20B, white light can be obtained from the light-emitting device 550W by selecting light-emitting layers 523Q_1, 523Q_2, and 523Q_3 such that the light emitted from these layers has a complementary color relationship.

[0417] The light emitting device 550W has a configuration in which the light emitting layer 523R of the light emitting device 550R is replaced with a light emitting layer 523Q_1 and the like, and the other configurations are the same as those of the light emitting device 550R.

[0418] The display device 500 shown in FIG. 21B is an example in which a light-emitting device 550R emitting red light, a light-emitting device 550G emitting green light, a light-emitting device 550B emitting blue light, and a light-emitting device 550W emitting white light all have a three-tiered tandem structure in which three light-emitting units are stacked. In FIG. 21B, the light-emitting device 550R has a light-emitting unit 512R_3 stacked on a light-emitting unit 512R_2 with a charge generation layer 531 interposed therebetween. The light-emitting unit 512R_3 includes a layer 522, a light-emitting layer 523R, a layer 524, and the like. The light-emitting unit 512R_3 can have a similar configuration to the light-emitting unit 512R_2. The same applies to the light-emitting unit 512G_3 included in the light-emitting device 550G, the light-emitting unit 512B_3 included in the light-emitting device 550B, and the light-emitting unit 512Q_3 included in the light-emitting device 550W.

[0419] FIG. 22A shows an example in which a light emitting device 550W that emits white light is provided in addition to the light emitting devices 550R, 550G, and 550B shown in FIG. 18A.

[0420] 22A has a configuration in which n light-emitting units (n is an integer of 2 or more) are stacked between a pair of electrodes (electrode 501, electrode 502) via a charge generation layer 531. The light-emitting device 550W has n light-emitting units, light-emitting unit 512Q_1 to light-emitting unit 512Q_n, and the light from these light-emitting units has a complementary color relationship, so that the light can emit white light.

[0421] 22B , a light emitting device 550R emitting red light, a light emitting device 550G emitting green light, a light emitting device 550B emitting blue light, and a light emitting device 550W emitting white light all have a configuration in which n light emitting units (n is an integer of 2 or more) are stacked. The light emitting device 550R has n light emitting units, light emitting unit 512R_1 to light emitting unit 512R_n, each having a light emitting layer that emits red light. The light emitting device 550G has n light emitting units, light emitting unit 512G_1 to light emitting unit 512G_n, each having a light emitting layer that emits green light. The light emitting device 550B has n light emitting units, light emitting unit 512B_1 to light emitting unit 512B_n, each having a light emitting layer that emits blue light.

[0422] In this way, by increasing the number of stacked light-emitting units, the luminance obtained from the light-emitting device with the same amount of current can be increased in proportion to the number of stacked light-emitting units.Furthermore, by increasing the number of stacked light-emitting units, the current required to obtain the same luminance can be reduced, and therefore the power consumption of the light-emitting device can be reduced in proportion to the number of stacked light-emitting units.

[0423] This embodiment mode can be combined with other embodiment modes as appropriate.

[0424] (Embodiment 3) In this embodiment, a display device of one embodiment of the present invention will be described with reference to FIGS.

[0425] The display device of the present embodiment can be a high-resolution display device or a large-sized display device. Therefore, the display device of the present embodiment can be used in electronic devices having relatively large screens, such as television devices, desktop or notebook personal computers, computer monitors, digital signage, large game machines such as pachinko machines, as well as display units of digital cameras, digital video cameras, digital photo frames, mobile phones, portable game machines, personal digital assistants, and sound reproducing devices.

[0426] [Display device 100A] FIG. 23 shows a perspective view of the display device 100A, and FIG. 24A shows a cross-sectional view of the display device 100A.

[0427] The display device 100A has a configuration in which a substrate 152 and a substrate 151 are bonded together. In Fig. 23, the substrate 152 is clearly indicated by a dashed line.

[0428] The display device 100A has a display unit 162, a circuit 164, wiring 165, etc. Fig. 23 shows an example in which an IC 173 and an FPC 172 are mounted on the display device 100A. Therefore, the configuration shown in Fig. 23 can also be said to be a display module having the display device 100A, an IC (integrated circuit), and an FPC.

[0429] The circuit 164 can be, for example, a scanning line driver circuit.

[0430] The wiring 165 has a function of supplying signals and power to the display unit 162 and the circuit 164. The signals and power are input to the wiring 165 from the outside via the FPC 172 or input to the wiring 165 from the IC 173.

[0431] 23 shows an example in which an IC 173 is provided on a substrate 151 by a COG (Chip On Glass) method or a COF (Chip On Film) method. The IC 173 may be, for example, an IC having a scanning line driving circuit or a signal line driving circuit. The display device 100A and the display module may be configured without an IC. Alternatively, the IC may be mounted on an FPC by a COF method or the like.

[0432] FIG. 24A shows an example of a cross section of display device 100A, where a part of the region including FPC 172, a part of circuit 164, a part of display unit 162, and a part of the region including the end portion are cut away.

[0433] The display device 100A shown in Figure 24A has, between substrate 151 and substrate 152, a transistor 201, a transistor 205, a light-emitting device 130a that emits red light, a light-emitting device 130b that emits green light, and a light-emitting device 130c that emits blue light, etc.

[0434] Here, when a pixel of a display device has three types of subpixels having light-emitting devices that emit light of different colors, the three subpixels include subpixels of three colors of R, G, and B, or subpixels of three colors of yellow (Y), cyan (C), and magenta (M), etc. When a pixel of a display device has four subpixels, the four subpixels include subpixels of four colors of R, G, B, and white (W), or subpixels of four colors of R, G, B, and Y, etc.

[0435] The light-emitting devices 130a, 130b, and 130c each have a similar structure to the stacked structure shown in FIG. 1B, except that they each have a conductive layer (conductive layers 126a, 126b, and 126c) between the pixel electrode and the EL layer. The light-emitting device 130a has the conductive layer 126a, the light-emitting device 130b has the conductive layer 126b, and the light-emitting device 130c has the conductive layer 126c. For details of the light-emitting devices, refer to Embodiment 1. The side surfaces of the pixel electrodes 111a, 111b, and 111c, the conductive layers 126a, 126b, and 126c, the first layer 113a, the second layer 113b, and the third layer 113c are covered with insulating layers 125 and 127, respectively. A fifth layer 114 is provided on the first layer 113a, the second layer 113b, the third layer 113c, and the insulating layers 125 and 127, and a common electrode 115 is provided on the fifth layer 114. In addition, a protective layer 131 is provided on each of the light-emitting devices 130a, 130b, and 130c. A protective layer 132 is provided on the protective layer 131.

[0436] The protective layer 132 and the substrate 152 are bonded via an adhesive layer 142. A solid sealing structure, a hollow sealing structure, or the like can be applied to seal the light-emitting device. In FIG. 24A, the space between the substrates 152 and 151 is filled with the adhesive layer 142, and a solid sealing structure is applied. Alternatively, the space may be filled with an inert gas (such as nitrogen or argon), and a hollow sealing structure may be applied. In this case, the adhesive layer 142 may be provided so as not to overlap with the light-emitting device. Alternatively, the space may be filled with a resin different from the frame-shaped adhesive layer 142.

[0437] The pixel electrodes 111 a, 111 b, and 111 c are connected to a conductive layer 222 b of the transistor 205 through openings provided in the insulating layer 214, respectively.

[0438] Recesses are formed in the pixel electrodes 111a, 111b, and 111c so as to cover the openings formed in the insulating layer 214. The recesses are preferably filled with a layer 128. It is preferable that a conductive layer 126a is formed over the pixel electrode 111a and the layer 128, a conductive layer 126b is formed over the pixel electrode 111b and the layer 128, and a conductive layer 126c is formed over the pixel electrode 111c and the layer 128. The conductive layers 126a, 126b, and 126c can also be referred to as pixel electrodes.

[0439] The layer 128 has a function of planarizing the recesses of the pixel electrodes 111a, 111b, and 111c. By providing the layer 128, unevenness of the surface on which the EL layer is formed can be reduced, and coverage can be improved. Furthermore, by providing conductive layers 126a, 126b, and 126c electrically connected to the pixel electrodes 111a, 111b, and 111c over the pixel electrodes 111a, 111b, and 111c and the layer 128, the regions overlapping with the recesses of the pixel electrodes 111a, 111b, and 111c can also be used as light-emitting regions in some cases. This can increase the aperture ratio of the pixel.

[0440] The layer 128 may be an insulating layer or a conductive layer. Various inorganic insulating materials, organic insulating materials, and conductive materials can be used as appropriate for the layer 128. In particular, the layer 128 is preferably formed using an insulating material.

[0441] An insulating layer containing an organic material can be suitably used as the layer 128. For example, acrylic resin, polyimide resin, epoxy resin, polyamide resin, polyimideamide resin, siloxane resin, benzocyclobutene resin, phenolic resin, precursors of these resins, or the like can be used as the layer 128. Alternatively, a photosensitive resin can be used as the layer 128. The photosensitive resin can be a positive-type material or a negative-type material.

[0442] By using a photosensitive resin, the layer 128 can be formed only by the steps of exposure and development, and the influence on the surfaces of the pixel electrodes 111a, 111b, and 111c of dry etching, wet etching, etc. can be reduced. Furthermore, by forming the layer 128 using a negative photosensitive resin, it may be possible to form the layer 128 using the same photomask (exposure mask) as that used to form the openings in the insulating layer 214.

[0443] The conductive layer 126a is provided on the pixel electrode 111a and the layer 128. The conductive layer 126a has a first region in contact with the upper surface of the pixel electrode 111a and a second region in contact with the upper surface of the layer 128. It is preferable that the height of the upper surface of the pixel electrode 111a in contact with the first region and the height of the upper surface of the layer 128 in contact with the second region are the same or approximately the same.

[0444] Similarly, the conductive layer 126b is provided on the pixel electrode 111b and the layer 128. The conductive layer 126b has a first region in contact with the upper surface of the pixel electrode 111b and a second region in contact with the upper surface of the layer 128. It is preferable that the height of the upper surface of the pixel electrode 111b in contact with the first region and the height of the upper surface of the layer 128 in contact with the second region are the same or approximately the same.

[0445] The conductive layer 126c is provided on the pixel electrode 111c and the layer 128. The conductive layer 126c has a first region in contact with the upper surface of the pixel electrode 111c and a second region in contact with the upper surface of the layer 128. It is preferable that the height of the upper surface of the pixel electrode 111c in contact with the first region and the height of the upper surface of the layer 128 in contact with the second region are the same or approximately the same.

[0446] The pixel electrodes include a material that reflects visible light, and the common electrode 115 (which may also be called a counter electrode) includes a material that transmits visible light.

[0447] The display device 100A is a top-emission type. Light emitted from the light-emitting device is emitted toward the substrate 152. The substrate 152 is preferably made of a material that is highly transparent to visible light.

[0448] The stacked structure from the substrate 151 to the insulating layer 214 corresponds to the layer 101 including the transistor in Embodiment 1.

[0449] The transistor 201 and the transistor 205 are both formed over a substrate 151. These transistors can be manufactured using the same material and in the same process.

[0450] An insulating layer 211, an insulating layer 213, an insulating layer 215, and an insulating layer 214 are provided over the substrate 151 in this order. A part of the insulating layer 211 functions as a gate insulating layer for each transistor. A part of the insulating layer 213 functions as a gate insulating layer for each transistor. The insulating layer 215 is provided to cover the transistor. The insulating layer 214 is provided to cover the transistor and functions as a planarization layer. Note that the number of gate insulating layers and the number of insulating layers covering the transistors are not limited, and each may be a single layer or two or more layers.

[0451] At least one insulating layer covering the transistor is preferably made of a material that is resistant to the diffusion of impurities such as water and hydrogen. This allows the insulating layer to function as a barrier layer. With this structure, it is possible to effectively prevent impurities from diffusing into the transistor from the outside, thereby improving the reliability of the display device.

[0452] It is preferable to use an inorganic insulating film for each of the insulating layers 211, 213, and 215. Examples of the inorganic insulating film that can be used include a silicon nitride film, a silicon oxynitride film, a silicon oxide film, a silicon nitride oxide film, an aluminum oxide film, and an aluminum nitride film. Alternatively, a hafnium oxide film, an yttrium oxide film, a zirconium oxide film, a gallium oxide film, a tantalum oxide film, a magnesium oxide film, a lanthanum oxide film, a cerium oxide film, and a neodymium oxide film may also be used. Two or more of the above insulating films may be stacked.

[0453] Here, organic insulating films often have lower barrier properties than inorganic insulating films. Therefore, it is preferable that the organic insulating film has an opening near the edge of the display device 100A. This can prevent impurities from entering from the edge of the display device 100A through the organic insulating film. Alternatively, the organic insulating film may be formed so that the edge of the organic insulating film is located inside the edge of the display device 100A, so that the organic insulating film is not exposed at the edge of the display device 100A.

[0454] An organic insulating film is suitable for the insulating layer 214, which functions as a planarization layer. Materials that can be used for the organic insulating film include acrylic resin, polyimide resin, epoxy resin, polyamide resin, polyimideamide resin, siloxane resin, benzocyclobutene resin, phenolic resin, and precursors of these resins. The insulating layer 214 may also have a laminated structure of an organic insulating film and an inorganic insulating film. The outermost layer of the insulating layer 214 preferably functions as an etching protection film. This can prevent recesses from being formed in the insulating layer 214 during processing of the pixel electrode 111a, the conductive layer 126a, etc. Alternatively, recesses may be formed in the insulating layer 214 during processing of the pixel electrode 111a, the conductive layer 126a, etc.

[0455] 24A, an opening is formed in insulating layer 214. This makes it possible to prevent impurities from entering display unit 162 from the outside through insulating layer 214, even when an organic insulating film is used for insulating layer 214. This makes it possible to improve the reliability of display device 100A.

[0456] The transistor 201 and the transistor 205 each include a conductive layer 221 that functions as a gate, an insulating layer 211 that functions as a gate insulating layer, conductive layers 222a and 222b that function as a source and a drain, a semiconductor layer 231, an insulating layer 213 that functions as a gate insulating layer, and a conductive layer 223 that functions as a gate. Here, the same hatching pattern is applied to multiple layers obtained by processing the same conductive film. The insulating layer 211 is located between the conductive layer 221 and the semiconductor layer 231. The insulating layer 213 is located between the conductive layer 223 and the semiconductor layer 231.

[0457] The structure of the transistor included in the display device of this embodiment is not particularly limited. For example, a planar transistor, a staggered transistor, an inverted staggered transistor, or the like can be used. Furthermore, either a top-gate transistor or a bottom-gate transistor structure may be used. Alternatively, gates may be provided above and below a semiconductor layer in which a channel is formed.

[0458] The transistor 201 and the transistor 205 have a structure in which a semiconductor layer in which a channel is formed is sandwiched between two gates. The two gates may be connected and the same signal may be supplied to drive the transistor. Alternatively, the threshold voltage of the transistor may be controlled by applying a potential for controlling the threshold voltage to one of the two gates and a potential for driving to the other.

[0459] The crystallinity of a semiconductor material used in a transistor is not particularly limited, and any of an amorphous semiconductor, a single crystal semiconductor, and a semiconductor having crystallinity other than a single crystal semiconductor (a microcrystalline semiconductor, a polycrystalline semiconductor, or a semiconductor having a crystalline region in part) may be used. The use of a single crystal semiconductor or a semiconductor having crystallinity is preferable because it can suppress deterioration of transistor characteristics.

[0460] The semiconductor layer of the transistor preferably contains metal oxide (also referred to as an oxide semiconductor). That is, the display device of this embodiment preferably uses a transistor using metal oxide in a channel formation region (hereinafter referred to as an OS transistor). Alternatively, the semiconductor layer of the transistor may contain silicon. Examples of silicon include amorphous silicon and crystalline silicon (such as low-temperature polysilicon and single-crystal silicon).

[0461] The semiconductor layer preferably contains, for example, indium, M (wherein M is one or more elements selected from gallium, aluminum, silicon, boron, yttrium, tin, copper, vanadium, beryllium, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, and magnesium), and zinc. In particular, M is preferably one or more elements selected from aluminum, gallium, yttrium, and tin.

[0462] 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.

[0463] When the semiconductor layer is an In-M-Zn oxide, the atomic ratio of In in the In-M-Zn oxide is preferably equal to or greater than the atomic ratio of M. Examples of atomic ratios of metal elements in such In-M-Zn oxides include compositions in which In:M:Zn=1:1:1 or thereabouts, In:M:Zn=1:1:1.2 or thereabouts, In:M:Zn=2:1:3 or thereabouts, In:M:Zn=3:1:2 or thereabouts, In:M:Zn=4:2:3 or thereabouts, In:M:Zn=4:2:4.1 or thereabouts, In:M:Zn=5:1:3 or thereabouts, In:M:Zn=5:1:6 or thereabouts, In:M:Zn=5:1:7 or thereabouts, In:M:Zn=5:1:8 or thereabouts, In:M:Zn=6:1:6 or thereabouts, and In:M:Zn=5:2:5 or thereabouts, etc. Note that "nearby compositions" includes a range of ±30% of the desired atomic ratio.

[0464] For example, when describing a composition with an atomic ratio of In:Ga:Zn=4:2:3 or thereabout, this includes a case where, when In is taken as 4, Ga is 1 to 3 and Zn is 2 to 4. Furthermore, when describing a composition with an atomic ratio of In:Ga:Zn=5:1:6 or thereabout, this includes a case where, when In is taken as 5, Ga is greater than 0.1 and 2 or less and Zn is 5 to 7 or less. Furthermore, when describing a composition with an atomic ratio of In:Ga:Zn=1:1:1 or thereabout, this includes a case where, when In is taken as 1, Ga is greater than 0.1 and 2 or less and Zn is greater than 0.1 and 2 or less.

[0465] The transistors included in the circuit 164 may have the same structure as or different from the transistors included in the display portion 162. The transistors included in the circuit 164 may all have the same structure or may have two or more types of structures. Similarly, the transistors included in the display portion 162 may all have the same structure or may have two or more types of structures.

[0466] 24B and 24C show other examples of transistor configurations.

[0467] The transistor 209 and the transistor 210 each include a conductive layer 221 functioning as a gate, an insulating layer 211 functioning as a gate insulating layer, a semiconductor layer 231 including a channel formation region 231i and a pair of low-resistance regions 231n, a conductive layer 222a connected to one of the pair of low-resistance regions 231n, a conductive layer 222b connected to the other of the pair of low-resistance regions 231n, an insulating layer 225 functioning as a gate insulating layer, a conductive layer 223 functioning as a gate, and an insulating layer 215 covering the conductive layer 223. The insulating layer 211 is located between the conductive layer 221 and the channel formation region 231i. The insulating layer 225 is located at least between the conductive layer 223 and the channel formation region 231i. An insulating layer 218 covering the transistor may also be provided.

[0468] 24B shows an example in which the insulating layer 225 covers the top surface and side surfaces of the semiconductor layer 231. The conductive layer 222a and the conductive layer 222b are connected to the low-resistance region 231n through openings provided in the insulating layer 225 and the insulating layer 215, respectively. One of the conductive layer 222a and the conductive layer 222b functions as a source, and the other functions as a drain.

[0469] 24C, the insulating layer 225 overlaps with the channel formation region 231i of the semiconductor layer 231 but does not overlap with the low-resistance region 231n. For example, the structure shown in FIG. 24C can be manufactured by processing the insulating layer 225 using the conductive layer 223 as a mask. In FIG. 24C, the insulating layer 215 is provided to cover the insulating layer 225 and the conductive layer 223, and the conductive layer 222a and the conductive layer 222b are each connected to the low-resistance region 231n through openings in the insulating layer 215.

[0470] A connection portion 204 is provided in a region of the substrate 151 where the substrate 152 does not overlap. In the connection portion 204, the wiring 165 is electrically connected to the FPC 172 via a conductive layer 166 and a connection layer 242. The conductive layer 166 has an example of a laminated structure including a conductive film obtained by processing the same conductive film as the pixel electrodes 111a, 111b, and 111c, and a conductive film obtained by processing the same conductive film as the conductive layers 126a, 126b, and 126c. The conductive layer 166 is exposed on the upper surface of the connection portion 204. This allows the connection portion 204 and the FPC 172 to be electrically connected via the connection layer 242.

[0471] It is preferable to provide a light-shielding layer 117 on the surface of substrate 152 facing substrate 151. In addition, various optical members can be arranged on the outside of substrate 152. Examples of optical members include a polarizing plate, a retardation plate, a light diffusion layer (such as a diffusion film), an anti-reflection layer, and a light-collecting film. In addition, an antistatic film that suppresses the adhesion of dust, a water-repellent film that makes it difficult for dirt to adhere, a hard coat film that suppresses the occurrence of scratches during use, an impact absorbing layer, etc. may be arranged on the outside of substrate 152.

[0472] By providing the protective layers 131 and 132 that cover the light emitting device, it is possible to prevent impurities such as water from entering the light emitting device, thereby improving the reliability of the light emitting device.

[0473] In a region 228 near the edge of the display device 100A, it is preferable that the insulating layer 215 and the protective layer 131 or the protective layer 132 contact each other through the opening in the insulating layer 214. In particular, it is preferable that the inorganic insulating films contact each other. This makes it possible to prevent impurities from entering the display unit 162 from the outside through the organic insulating film. This can therefore improve the reliability of the display device 100A.

[0474] The substrate 151 and the substrate 152 can each be made of glass, quartz, ceramic, sapphire, resin, metal, alloy, semiconductor, or the like. A material that transmits light is used for the substrate on the side from which light from the light-emitting device is extracted. Using a flexible material for the substrate 151 and the substrate 152 can increase the flexibility of the display device. Alternatively, a polarizing plate may be used for the substrate 151 or the substrate 152.

[0475] Substrates 151 and 152 can be made of polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyacrylonitrile resin, acrylic resin, polyimide resin, polymethyl methacrylate resin, polycarbonate (PC) resin, polyethersulfone (PES) resin, polyamide resin (nylon, aramid, etc.), polysiloxane resin, cycloolefin resin, polystyrene resin, polyamideimide resin, polyurethane resin, polyvinyl chloride resin, polyvinylidene chloride resin, polypropylene resin, polytetrafluoroethylene (PTFE) resin, ABS resin, cellulose nanofiber, etc. One or both of substrates 151 and 152 may be made of glass having a thickness sufficient to provide flexibility.

[0476] When a circularly polarizing plate is superimposed on a display device, it is preferable that the display device has a substrate with high optical isotropy. A substrate with high optical isotropy has small birefringence (or a small amount of birefringence).

[0477] The absolute value of the retardation (phase difference) of a substrate having high optical isotropy is preferably 30 nm or less, more preferably 20 nm or less, and even more preferably 10 nm or less.

[0478] Examples of films with high optical isotropy include triacetyl cellulose (TAC, also known as cellulose triacetate) films, cycloolefin polymer (COP) films, cycloolefin copolymer (COC) films, and acrylic films.

[0479] Furthermore, when a film is used as a substrate, the film may absorb water, causing deformation such as wrinkles in the display panel. Therefore, it is preferable to use a film with low water absorption for the substrate. For example, it is preferable to use a film with a water absorption rate of 1% or less, more preferably 0.1% or less, and even more preferably 0.01% or less.

[0480] The adhesive layer 142 can be made of various curable adhesives, such as a photo-curable adhesive (e.g., an ultraviolet curable adhesive), a reactive curable adhesive, a thermosetting adhesive, or an anaerobic adhesive. Examples of such adhesives include epoxy resin, acrylic resin, silicone resin, phenolic resin, polyimide resin, imide resin, PVC (polyvinyl chloride) resin, PVB (polyvinyl butyral) resin, and EVA (ethylene vinyl acetate) resin. In particular, a material with low moisture permeability, such as epoxy resin, is preferable. Alternatively, a two-component resin may be used. Alternatively, an adhesive sheet or the like may be used.

[0481] The connection layer 242 may be made of an anisotropic conductive film (ACF), an anisotropic conductive paste (ACP), or the like.

[0482] Materials that can be used for conductive layers such as the gate, source, and drain of a transistor, as well as various wirings and electrodes that constitute a display device include metals such as aluminum, titanium, chromium, nickel, copper, yttrium, zirconium, molybdenum, silver, tantalum, and tungsten, and alloys containing these metals as main components, etc. Films containing these materials can be used as a single layer or a stacked layer structure.

[0483] Examples of light-transmitting conductive materials include conductive oxides such as indium oxide, indium tin oxide, indium zinc oxide, zinc oxide, and zinc oxide containing gallium, or graphene. Alternatively, metal materials such as gold, silver, platinum, magnesium, nickel, tungsten, chromium, molybdenum, iron, cobalt, copper, palladium, and titanium, or alloy materials containing such metal materials, can be used. Alternatively, nitrides of such metal materials (e.g., titanium nitride) can be used. When using metal materials or alloy materials (or their nitrides), it is preferable to thin them sufficiently to ensure light-transmitting properties. A stacked film of the above materials can also be used as the conductive layer. For example, a stacked film of an alloy of silver and magnesium and indium tin oxide is preferable because it can enhance conductivity. These materials can also be used for conductive layers such as various wirings and electrodes constituting a display device, and conductive layers (conductive layers functioning as pixel electrodes or common electrodes) in light-emitting devices.

[0484] Examples of insulating materials that can be used for each insulating layer include resins such as acrylic resin and epoxy resin, and inorganic insulating materials such as silicon oxide, silicon oxynitride, silicon nitride oxide, silicon nitride, and aluminum oxide.

[0485] [Display device 100B] 25 is different from the display device 100A mainly in that it is a bottom emission type. Note that a description of the same parts as the display device 100A will be omitted.

[0486] Light emitted from the light emitting device is emitted toward the substrate 151. It is preferable that a material that is highly transparent to visible light is used for the substrate 151. On the other hand, the light-transmitting property of the material used for the substrate 152 is not an issue.

[0487] It is preferable to form a light-shielding layer 117 between the substrate 151 and the transistor 201 and between the substrate 151 and the transistor 205. Fig. 25 shows an example in which the light-shielding layer 117 is provided over the substrate 151, the insulating layer 153 is provided over the light-shielding layer 117, and the transistors 201, 205, etc. are provided over the insulating layer 153.

[0488] This embodiment mode can be combined with other embodiment modes as appropriate.

[0489] (Fourth embodiment) In this embodiment, a display device of one embodiment of the present invention will be described with reference to FIGS.

[0490] The display device of the present embodiment can be a high-definition display device, and can therefore be used as a display unit for information terminals (wearable devices) such as wristwatches and bracelets, as well as for wearable devices that can be worn on the head, such as VR devices such as head-mounted displays and AR devices such as glasses.

[0491] [Display module] 26A shows a perspective view of display module 280. Display module 280 has display device 100C and FPC 290. Note that the display device included in display module 280 is not limited to display device 100C, and may be display device 100D or display device 100E, which will be described later.

[0492] The display module 280 has a substrate 291 and a substrate 292. The display module 280 has a display unit 281. The display unit 281 is a region that displays an image in the display module 280, and is a region where light from each pixel provided in a pixel unit 284 (described later) can be viewed.

[0493] 26B is a perspective view schematically showing the configuration on the substrate 291 side. A circuit section 282, a pixel circuit section 283 on the circuit section 282, and a pixel section 284 on the pixel circuit section 283 are stacked on the substrate 291. A terminal section 285 for connecting to an FPC 290 is provided in a portion of the substrate 291 that does not overlap with the pixel section 284. The terminal section 285 and the circuit section 282 are electrically connected by a wiring section 286 composed of a plurality of wirings.

[0494] The pixel section 284 has a plurality of periodically arranged pixels 284a. An enlarged view of one pixel 284a is shown on the right side of FIG. 26B. The pixel 284a has light-emitting devices 130a, 130b, and 130c that emit light of different colors. The plurality of light-emitting devices can be arranged in a stripe array as shown in FIG. 26B. Various light-emitting device arrangement methods, such as a delta array or a pentile array, can also be used.

[0495] The pixel circuit section 283 has a plurality of pixel circuits 283a arranged periodically.

[0496] One pixel circuit 283a is a circuit that controls the light emission of three light-emitting devices included in one pixel 284a. One pixel circuit 283a may be configured to have three circuits that control the light emission of one light-emitting device. For example, the pixel circuit 283a may be configured to have at least one selection transistor, one current control transistor (drive transistor), and a capacitance element for each light-emitting device. In this case, a gate signal is input to the gate of the selection transistor, and a source signal is input to either the source or the drain. This realizes an active matrix display device.

[0497] The circuit portion 282 includes a circuit for driving each pixel circuit 283a of the pixel circuit portion 283. For example, it is preferable that the circuit portion 282 includes one or both of a gate line driver circuit and a source line driver circuit. In addition, the circuit portion 282 may include at least one of an arithmetic circuit, a memory circuit, a power supply circuit, and the like.

[0498] The FPC 290 functions as wiring for supplying a video signal, a power supply potential, or the like from the outside to the circuit section 282. An IC may also be mounted on the FPC 290.

[0499] The display module 280 can be configured such that one or both of the pixel circuit unit 283 and the circuit unit 282 are provided overlapping below the pixel unit 284, thereby enabling the aperture ratio (effective display area ratio) of the display unit 281 to be extremely high. For example, the aperture ratio of the display unit 281 can be set to 40% or more and less than 100%, preferably 50% or more and 95% or less, and more preferably 60% or more and 95% or less. Furthermore, the pixels 284a can be arranged at an extremely high density, enabling the resolution of the display unit 281 to be extremely high. For example, it is preferable that the pixels 284a are arranged in the display unit 281 at a resolution of 2000 ppi or more, preferably 3000 ppi or more, more preferably 5000 ppi or more, and even more preferably 6000 ppi or more, and 20000 ppi or less, or 30000 ppi or less.

[0500] Such a display module 280 has extremely high resolution and can therefore be suitably used in VR devices such as head-mounted displays or eyeglass-type AR devices. For example, even in a configuration in which the display unit of the display module 280 is viewed through lenses, the display module 280 has an extremely high-resolution display unit 281, so that even if the display unit is enlarged with the lenses, the pixels are not visible, allowing for a highly immersive display. Furthermore, the display module 280 is not limited to this, and can be suitably used in electronic devices having relatively small display units. For example, it can be suitably used in the display unit of a wearable electronic device such as a wristwatch.

[0501] [Display device 100C] The display device 100C shown in FIG. 27 includes a substrate 301, light emitting devices 130a, 130b, and 130c, a capacitor 240, and a transistor 310.

[0502] 26A and 26B. The stacked structure from the substrate 301 to the insulating layer 255b corresponds to the layer 101 including the transistor in the first embodiment.

[0503] The transistor 310 has a channel formation region in a substrate 301. The substrate 301 can be, for example, a semiconductor substrate such as a single crystal silicon substrate. The transistor 310 includes a part of the substrate 301, a conductive layer 311, a low-resistance region 312, an insulating layer 313, and an insulating layer 314. The conductive layer 311 functions as a gate electrode. The insulating layer 313 is located between the substrate 301 and the conductive layer 311 and functions as a gate insulating layer. The low-resistance region 312 is a region in which the substrate 301 is doped with impurities and functions as either a source or a drain. The insulating layer 314 is provided to cover a side surface of the conductive layer 311.

[0504] Furthermore, an element isolation layer 315 is provided between two adjacent transistors 310 so as to be embedded in the substrate 301 .

[0505] In addition, an insulating layer 261 is provided to cover the transistor 310 , and a capacitor 240 is provided on the insulating layer 261 .

[0506] Capacitor 240 has conductive layer 241, conductive layer 245, and insulating layer 243 positioned therebetween. Conductive layer 241 functions as one electrode of capacitor 240, conductive layer 245 functions as the other electrode of capacitor 240, and insulating layer 243 functions as a dielectric of capacitor 240.

[0507] The conductive layer 241 is provided over the insulating layer 261 and is buried in the insulating layer 254. The conductive layer 241 is electrically connected to one of the source and drain of the transistor 310 by a plug 271 buried in the insulating layer 261. The insulating layer 243 is provided to cover the conductive layer 241. The conductive layer 245 is provided in a region overlapping with the conductive layer 241 with the insulating layer 243 interposed therebetween.

[0508] An insulating layer 255a is provided to cover the capacitor 240, an insulating layer 255b is provided on the insulating layer 255a, and light-emitting devices 130a, 130b, 130c, etc. are provided on the insulating layer 255b. In this embodiment, an example is shown in which the light-emitting devices 130a, 130b, 130c have a stacked structure similar to the stacked structure shown in FIG. 1B. Side surfaces of the pixel electrodes 111a, 111b, 111c, the first layer 113a, the second layer 113b, and the third layer 113c are covered with insulating layers 125 and 127, respectively. A fifth layer 114 is provided on the first layer 113a, the second layer 113b, the third layer 113c, and the insulating layers 125 and 127, and a common electrode 115 is provided on the fifth layer 114. Furthermore, protective layer 131 is provided on light-emitting devices 130a, 130b, and 130c. Protective layer 132 is provided on protective layer 131, and substrate 120 is bonded to protective layer 132 via resin layer 122. For details about the components from the light-emitting devices to substrate 120, refer to embodiment 1. Substrate 120 corresponds to substrate 292 in FIG. 26A.

[0509] The insulating layers 255a and 255b can be formed using various inorganic insulating films such as an insulating oxide film, an insulating nitride film, an insulating oxynitride film, and an insulating nitride oxide film. The insulating layer 255a is preferably formed using an insulating oxide film or an insulating oxynitride film such as a silicon oxide film, a silicon oxynitride film, or an aluminum oxide film. The insulating layer 255b is preferably formed using a nitride insulating film or an insulating nitride oxide film such as a silicon nitride film or a silicon nitride oxide film. More specifically, the insulating layer 255a is preferably formed using a silicon oxide film, and the insulating layer 255b is preferably formed using a silicon nitride film. The insulating layer 255b preferably functions as an etching protective film. Alternatively, the insulating layer 255a may be formed using a nitride insulating film or a nitride oxide insulating film, and the insulating layer 255b may be formed using an insulating oxide insulating film or an oxynitride insulating film. Although this embodiment illustrates an example in which a recess is provided in the insulating layer 255b, the insulating layer 255b does not necessarily have a recess.

[0510] The pixel electrode of the light-emitting device is electrically connected to one of the source and drain of the transistor 310 via a plug 256 embedded in the insulating layers 255a and 255b, a conductive layer 241 embedded in the insulating layer 254, and a plug 271 embedded in the insulating layer 261. The height of the top surface of the insulating layer 255b and the height of the top surface of the plug 256 are the same or approximately the same. Various conductive materials can be used for the plug.

[0511] In this specification, the phrase "the height of A and the height of B are the same or approximately the same" includes cases where the height of A and the height of B are the same, and also includes cases where a difference occurs between the height of A and the height of B due to a manufacturing error when the heights of A and B are made to be the same.

[0512] For example, an insulating layer 261 is formed, an opening is provided in the insulating layer 261, a conductive layer to be the plug 271 is formed so as to fill the opening, and then a planarization process is performed using a chemical mechanical polishing (CMP) method or the like. This makes it possible to realize a configuration in which the height of the upper surface of the plug 271 and the height of the upper surface of the insulating layer 261 are the same or approximately the same.

[0513] [Display device 100D] 28 is different from the display device 100C mainly in the configuration of the transistors. Note that a description of the same parts as those of the display device 100C may be omitted.

[0514] The transistor 320 is a transistor (OS transistor) in which a metal oxide (also referred to as an oxide semiconductor) is used for a semiconductor layer in which a channel is formed.

[0515] The transistor 320 includes a semiconductor layer 321 , an insulating layer 323 , a conductive layer 324 , a pair of conductive layers 325 , an insulating layer 326 , and a conductive layer 327 .

[0516] 26A and 26B. The stacked structure from the substrate 331 to the insulating layer 255b corresponds to the layer 101 including the transistor in Embodiment 1. The substrate 331 can be an insulating substrate or a semiconductor substrate.

[0517] An insulating layer 332 is provided over a substrate 331. The insulating layer 332 functions as a barrier layer that prevents impurities such as water or hydrogen from diffusing from the substrate 331 to the transistor 320 and prevents oxygen from being released from the semiconductor layer 321 toward the insulating layer 332. The insulating layer 332 can be, for example, a film through which hydrogen or oxygen is less likely to diffuse than a silicon oxide film, such as an aluminum oxide film, a hafnium oxide film, or a silicon nitride film.

[0518] A conductive layer 327 is provided over the insulating layer 332, and an insulating layer 326 is provided to cover the conductive layer 327. The conductive layer 327 functions as a first gate electrode of the transistor 320, and part of the insulating layer 326 functions as a first gate insulating layer. An oxide insulating film such as a silicon oxide film is preferably used for at least a portion of the insulating layer 326 that is in contact with the semiconductor layer 321. The top surface of the insulating layer 326 is preferably planarized.

[0519] The semiconductor layer 321 is provided over the insulating layer 326. The semiconductor layer 321 preferably includes a metal oxide (also referred to as an oxide semiconductor) film having semiconductor properties. Materials that can be suitably used for the semiconductor layer 321 will be described in detail later.

[0520] A pair of conductive layers 325 is provided over and in contact with the semiconductor layer 321 and functions as a source electrode and a drain electrode.

[0521] An insulating layer 328 is provided to cover top surfaces and side surfaces of the pair of conductive layers 325 and side surfaces of the semiconductor layer 321, and an insulating layer 264 is provided over the insulating layer 328. The insulating layer 328 functions as a barrier layer that prevents impurities such as water or hydrogen from diffusing from the insulating layer 264 or the like to the semiconductor layer 321 and prevents oxygen from being released from the semiconductor layer 321. The insulating layer 328 can be an insulating film similar to the insulating layer 332.

[0522] An opening reaching the semiconductor layer 321 is provided in the insulating layer 328 and the insulating layer 264. An insulating layer 323 and a conductive layer 324 are buried inside the opening and are in contact with the side surfaces of the insulating layer 264, the insulating layer 328, and the conductive layer 325 and the top surface of the semiconductor layer 321. The conductive layer 324 functions as a second gate electrode, and the insulating layer 323 functions as a second gate insulating layer.

[0523] The upper surfaces of the conductive layer 324, the insulating layer 323, and the insulating layer 264 are planarized so that their heights are the same or approximately the same, and insulating layers 329 and 265 are provided to cover them.

[0524] The insulating layer 264 and the insulating layer 265 function as interlayer insulating layers. The insulating layer 329 functions as a barrier layer that prevents impurities such as water or hydrogen from diffusing from the insulating layer 265 or the like to the transistor 320. The insulating layer 329 can be formed using an insulating film similar to the insulating layer 328 and the insulating layer 332.

[0525] A plug 274 electrically connected to one of the pair of conductive layers 325 is provided to be embedded in the insulating layer 265, the insulating layer 329, and the insulating layer 264. Here, the plug 274 preferably includes a conductive layer 274a covering the side surfaces of the openings in the insulating layer 265, the insulating layer 329, the insulating layer 264, and the insulating layer 328 and part of the top surface of the conductive layer 325, and a conductive layer 274b in contact with the top surface of the conductive layer 274a. In this case, the conductive layer 274a is preferably made of a conductive material through which hydrogen and oxygen do not easily diffuse.

[0526] In the display device 100D, the configuration from the insulating layer 254 to the substrate 120 is the same as that of the display device 100C.

[0527] [Display device 100E] 29 has a stacked structure of a transistor 310 having a channel formed in a substrate 301 and a transistor 320 having a channel formed in a semiconductor layer containing a metal oxide. Note that descriptions of parts similar to those of the display devices 100C and 100D may be omitted.

[0528] An insulating layer 261 is provided to cover the transistor 310, and a conductive layer 251 is provided over the insulating layer 261. An insulating layer 262 is provided to cover the conductive layer 251, and a conductive layer 252 is provided over the insulating layer 262. The conductive layers 251 and 252 each function as wirings. An insulating layer 263 and an insulating layer 332 are provided to cover the conductive layer 252, and a transistor 320 is provided over the insulating layer 332. An insulating layer 265 is provided to cover the transistor 320, and a capacitor 240 is provided over the insulating layer 265. The capacitor 240 and the transistor 320 are electrically connected by a plug 274.

[0529] The transistor 320 can be used as a transistor included in a pixel circuit. The transistor 310 can be used as a transistor included in a pixel circuit or a driver circuit (gate line driver circuit, source line driver circuit) for driving the pixel circuit. The transistors 310 and 320 can be used as transistors included in various circuits such as an arithmetic circuit or a memory circuit.

[0530] By using this configuration, not only pixel circuits but also driving circuits etc. can be formed directly below the light-emitting device, making it possible to make the display device smaller than when driving circuits are provided around the periphery of the display area.

[0531] This embodiment mode can be combined with other embodiment modes as appropriate.

[0532] (Embodiment 5) In this embodiment, a structural example of a transistor that can be applied to a display device of one embodiment of the present invention will be described, particularly the case where a transistor containing silicon as a semiconductor in which a channel is formed will be described.

[0533] One embodiment of the present invention is a display device including a light-emitting device and a pixel circuit. The display device can achieve a full-color display device by including three types of light-emitting devices that emit red (R), green (G), and blue (B) light, respectively.

[0534] It is preferable that all transistors included in a pixel circuit that drives a light-emitting device use transistors that have silicon in a semiconductor layer where a channel is formed. Examples of silicon include single-crystal silicon, polycrystalline silicon, and amorphous silicon. In particular, it is preferable to use transistors that have low-temperature polysilicon (LTPS) in the semiconductor layer (hereinafter also referred to as LTPS transistors). LTPS transistors have high field-effect mobility and good frequency characteristics.

[0535] By using silicon transistors such as LTPS transistors, circuits that need to be driven at high frequencies (such as source driver circuits) can be built on the same substrate as the display unit, which simplifies the external circuits mounted on the display device and reduces component and mounting costs.

[0536] At least one of the transistors included in the pixel circuit preferably uses a transistor (hereinafter also referred to as an OS transistor) having a metal oxide (hereinafter also referred to as an oxide semiconductor) as a semiconductor in which a channel is formed. The OS transistor has significantly higher field-effect mobility than an amorphous silicon transistor. Furthermore, the OS transistor has a significantly smaller source-drain leakage current in an off state (hereinafter also referred to as an off-state current), and can retain charge accumulated in a capacitor connected in series with the transistor for a long period of time. Furthermore, the use of an OS transistor can reduce the power consumption of a display device.

[0537] By using LTPS transistors for some of the transistors included in a pixel circuit and OS transistors for the other transistors, a display device with low power consumption and high driving capability can be realized. As a more preferred example, it is preferable to use OS transistors as transistors that function as switches for controlling conduction / non-conduction between wirings and LTPS transistors as transistors that control current.

[0538] For example, one of the transistors provided in the pixel circuit functions as a transistor for controlling the current flowing through the light-emitting device and can be called a driving transistor. One of the source and drain of the driving transistor is electrically connected to the pixel electrode of the light-emitting device. It is preferable to use an LTPS transistor as the driving transistor. This allows the current flowing through the light-emitting device in the pixel circuit to be increased.

[0539] On the other hand, another transistor provided in the pixel circuit functions as a switch for controlling pixel selection / non-selection and can also be called a selection transistor. The gate of the selection transistor is electrically connected to a gate line, and one of the source and drain is electrically connected to a source line (signal line). It is preferable to use an OS transistor as the selection transistor. This allows the gradation of the pixel to be maintained even when the frame frequency is significantly reduced (for example, 1 fps or less), so power consumption can be reduced by stopping the driver when displaying a still image.

[0540] A more specific configuration example will be described below with reference to the drawings.

[0541] [Display device configuration example 2] 30A shows a block diagram of the display device 10. The display device 10 includes a display unit 11, a drive circuit unit 12, a drive circuit unit 13, and the like.

[0542] The display unit 11 has a plurality of pixels 30 arranged in a matrix. Each pixel 30 has sub-pixels 21R, 21G, and 21B. Each of the sub-pixels 21R, 21G, and 21B has a light-emitting device that functions as a display device.

[0543] The pixel 30 is electrically connected to the wiring GL, the wiring SLR, the wiring SLG, and the wiring SLB. The wiring SLR, the wiring SLG, and the wiring SLB are each electrically connected to the drive circuit unit 12. The wiring GL is electrically connected to the drive circuit unit 13. The drive circuit unit 12 functions as a source line drive circuit (also referred to as a source driver), and the drive circuit unit 13 functions as a gate line drive circuit (also referred to as a gate driver). The wiring GL functions as a gate line, and the wiring SLR, the wiring SLG, and the wiring SLB each function as a source line.

[0544] Subpixel 21R has a light-emitting device that emits red light. Subpixel 21G has a light-emitting device that emits green light. Subpixel 21B has a light-emitting device that emits blue light. This allows display device 10 to perform full-color display. Note that pixel 30 may also have subpixels that have light-emitting devices that emit light of other colors. For example, pixel 30 may have, in addition to the above three subpixels, a subpixel that has a light-emitting device that emits white light or a subpixel that has a light-emitting device that emits yellow light.

[0545] The wiring GL is electrically connected to the sub-pixels 21R, 21G, and 21B arranged in the row direction (extension direction of the wiring GL). The wiring SLR, wiring SLG, and wiring SLB are electrically connected to the sub-pixels 21R, 21G, and 21B (not shown) arranged in the column direction (extension direction of the wiring SLR, etc.), respectively.

[0546] [Pixel circuit configuration example] 30B shows an example of a circuit diagram of a pixel 21 that can be applied to the subpixels 21R, 21G, and 21B. The pixel 21 includes a transistor M1, a transistor M2, a transistor M3, a capacitor C1, and a light-emitting device EL. The pixel 21 is also electrically connected to a line GL and a line SL. The line SL corresponds to any one of the line SLR, line SLG, and line SLB shown in FIG. 30A.

[0547] The transistor M1 has a gate electrically connected to a wiring GL, one of a source and a drain electrically connected to a wiring SL, and the other electrically connected to one electrode of a capacitor C1 and the gate of the transistor M2. The transistor M2 has one of a source and a drain electrically connected to a wiring AL, and the other of a source and a drain electrically connected to one electrode of a light-emitting device EL, the other electrode of the capacitor C1, and one of a source and a drain of the transistor M3. The transistor M3 has a gate electrically connected to a wiring GL, and the other of a source and a drain electrically connected to a wiring RL. The light-emitting device EL has the other electrode electrically connected to a wiring CL.

[0548] A data potential is applied to the wiring SL, and a selection signal is applied to the wiring GL. The selection signal includes a potential that turns on a transistor and a potential that turns off a transistor.

[0549] A reset potential is applied to the wiring RL. An anode potential is applied to the wiring AL. A cathode potential is applied to the wiring CL. In the pixel 21, the anode potential is higher than the cathode potential. The reset potential applied to the wiring RL can be a potential such that the potential difference between the reset potential and the cathode potential is smaller than the threshold voltage of the light-emitting device EL. The reset potential can be a potential higher than the cathode potential, the same as the cathode potential, or a potential lower than the cathode potential.

[0550] The transistors M1 and M3 function as switches. The transistor M2 functions as a transistor for controlling the current flowing through the light-emitting device EL. For example, it can be said that the transistor M1 functions as a selection transistor and the transistor M2 functions as a drive transistor.

[0551] Here, it is preferable that all of the transistors M1 to M3 be LTPS transistors. Alternatively, it is preferable that the transistors M1 and M3 be OS transistors and the transistor M2 be an LTPS transistor.

[0552] Alternatively, OS transistors may be used for all of the transistors M1 to M3. In this case, an LTPS transistor may be used for one or more of the transistors included in the driver circuit unit 12 and the driver circuit unit 13, and OS transistors may be used for the remaining transistors. For example, OS transistors may be used for the transistors provided in the display unit 11, and LTPS transistors may be used for the transistors provided in the driver circuit unit 12 and the driver circuit unit 13.

[0553] The OS transistor may be a transistor including an oxide semiconductor in a semiconductor layer in which a channel is formed. The semiconductor layer preferably contains, 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. In particular, an oxide containing indium, gallium, and zinc (also referred to as IGZO) is preferably used for the semiconductor layer of the OS transistor. Alternatively, an oxide containing indium, tin, and zinc is preferably used. Alternatively, an oxide containing indium, gallium, tin, and zinc is preferably used.

[0554] A transistor using an oxide semiconductor, which has a wider band gap and a lower carrier concentration than silicon, can achieve an extremely small off-state current. Therefore, the small off-state current allows charge stored in a capacitor connected in series with the transistor to be held for a long period of time. Therefore, it is preferable to use transistors including oxide semiconductors for the transistors M1 and M3 connected in series with the capacitor C1. Using transistors including oxide semiconductors as the transistors M1 and M3 can prevent charge stored in the capacitor C1 from leaking through the transistor M1 or M3. Furthermore, because charge stored in the capacitor C1 can be held for a long period of time, a still image can be displayed for a long period of time without rewriting data in the pixel 21.

[0555] Note that although the transistors are shown as n-channel transistors in FIG. 30B, p-channel transistors can also be used.

[0556] Moreover, it is preferable that the transistors included in the pixel 21 are formed side by side on the same substrate.

[0557] The transistor included in the pixel 21 can be a transistor having a pair of gates that overlap with each other with a semiconductor layer interposed therebetween.

[0558] In a transistor having a pair of gates, when the pair of gates are electrically connected to each other and supplied with the same potential, the on-state current of the transistor is increased and the saturation characteristics are improved. A potential for controlling the threshold voltage of the transistor may be supplied to one of the pair of gates. Supplying a constant potential to one of the pair of gates can improve the stability of the electrical characteristics of the transistor. For example, one gate of the transistor may be electrically connected to a wiring to which a constant potential is supplied, or to its own source or drain.

[0559] 30C is an example in which the transistors M1 and M3 each have a pair of gates. The pair of gates of the transistors M1 and M3 are electrically connected. With this configuration, the period for writing data to the pixel 21 can be shortened.

[0560] 30D is an example in which a transistor having a pair of gates is used for the transistor M2 in addition to the transistors M1 and M3. The pair of gates of the transistor M2 are electrically connected. By using such a transistor for the transistor M2, the saturation characteristics are improved, which makes it easier to control the emission luminance of the light-emitting device EL and improves the display quality.

[0561] [Transistor configuration example] An example of a cross-sectional structure of a transistor that can be applied to the display device will be described below.

[0562] [Configuration example 1] FIG. 31A is a cross-sectional view including a transistor 410.

[0563] The transistor 410 is provided on the substrate 401 and has a semiconductor layer made of polycrystalline silicon. For example, the transistor 410 corresponds to the transistor M2 of the pixel 21. That is, Fig. 31A shows an example in which one of the source and drain of the transistor 410 is electrically connected to the conductive layer 431 of the light-emitting device.

[0564] The transistor 410 includes a semiconductor layer 411, an insulating layer 412, a conductive layer 413, and the like. The semiconductor layer 411 includes a channel formation region 411i and a low-resistance region 411n. The semiconductor layer 411 includes silicon. The semiconductor layer 411 preferably includes polycrystalline silicon. Part of the insulating layer 412 functions as a gate insulating layer. Part of the conductive layer 413 functions as a gate electrode.

[0565] Note that the semiconductor layer 411 can also include a metal oxide (also referred to as an oxide semiconductor) that exhibits semiconductor characteristics. In this case, the transistor 410 can be called an OS transistor.

[0566] The low-resistance region 411n is a region containing an impurity element. For example, when the transistor 410 is an n-channel transistor, phosphorus, arsenic, or the like may be added to the low-resistance region 411n. On the other hand, when the transistor 410 is a p-channel transistor, boron, aluminum, or the like may be added to the low-resistance region 411n. Furthermore, in order to control the threshold voltage of the transistor 410, the above-mentioned impurities may be added to the channel formation region 411i.

[0567] An insulating layer 421 is provided over a substrate 401. A semiconductor layer 411 is provided over the insulating layer 421. An insulating layer 412 is provided to cover the semiconductor layer 411 and the insulating layer 421. A conductive layer 413 is provided over the insulating layer 412 so as to overlap with the semiconductor layer 411.

[0568] An insulating layer 422 is provided to cover the conductive layer 413 and the insulating layer 412. A conductive layer 414a and a conductive layer 414b are provided over the insulating layer 422. The conductive layer 414a and the conductive layer 414b are electrically connected to the low-resistance region 411n through openings provided in the insulating layer 422 and the insulating layer 412. Part of the conductive layer 414a functions as one of the source and drain electrodes, and part of the conductive layer 414b functions as the other of the source and drain electrodes. An insulating layer 423 is provided to cover the conductive layer 414a, the conductive layer 414b, and the insulating layer 422.

[0569] A conductive layer 431 functioning as a pixel electrode is provided over the insulating layer 423. The conductive layer 431 is provided over the insulating layer 423 and is electrically connected to the conductive layer 414b through an opening provided in the insulating layer 423. Although not shown here, an EL layer and a common electrode can be stacked over the conductive layer 431.

[0570] [Configuration example 2] 31B shows a transistor 410a having a pair of gate electrodes, which differs from the transistor 410a shown in FIG. 31B mainly in that a conductive layer 415 and an insulating layer 416 are included.

[0571] The conductive layer 415 is provided over the insulating layer 421. An insulating layer 416 is provided to cover the conductive layer 415 and the insulating layer 421. The semiconductor layer 411 is provided so that at least a channel formation region 411i overlaps with the conductive layer 415 with the insulating layer 416 interposed therebetween.

[0572] 31B, part of the conductive layer 413 functions as a first gate electrode, and part of the conductive layer 415 functions as a second gate electrode. In this case, part of the insulating layer 412 functions as a first gate insulating layer, and part of the insulating layer 416 functions as a second gate insulating layer.

[0573] Here, when the first gate electrode and the second gate electrode are electrically connected, the conductive layer 413 and the conductive layer 415 may be electrically connected through openings provided in the insulating layers 412 and 416 in a region not shown. When the second gate electrode and the source or drain are electrically connected, the conductive layer 414a or the conductive layer 414b may be electrically connected to the conductive layer 415 through openings provided in the insulating layers 422, 412, and 416 in a region not shown.

[0574] When LTPS transistors are used for all of the transistors constituting pixel 21, it is possible to use transistor 410 illustrated in Fig. 31A or transistor 410a illustrated in Fig. 31B. In this case, transistor 410a may be used for all of the transistors constituting pixel 21, transistor 410 may be used for all of the transistors, or transistor 410a and transistor 410 may be used in combination.

[0575] [Configuration Example 3] An example of a structure including both a transistor in which silicon is used for a semiconductor layer and a transistor in which metal oxide is used for a semiconductor layer will be described below.

[0576] FIG. 31C shows a cross-sectional schematic diagram including transistor 410a and transistor 450.

[0577] The transistor 410a can be the same as in Structure Example 1. Note that although the example using the transistor 410a is described here, a structure including the transistor 410 and the transistor 450 may be used, or a structure including all of the transistors 410, 410a, and 450 may be used.

[0578] The transistor 450 is a transistor in which a metal oxide is used for a semiconductor layer. The configuration shown in Fig. 31C is an example in which the transistor 450 corresponds to the transistor M1 of the pixel 21, and the transistor 410a corresponds to the transistor M2. That is, Fig. 31C shows an example in which one of the source and the drain of the transistor 410a is electrically connected to the conductive layer 431.

[0579] FIG. 31C also shows an example in which transistor 450 has a pair of gates.

[0580] The transistor 450 includes a conductive layer 455, an insulating layer 422, a semiconductor layer 451, an insulating layer 452, a conductive layer 453, and the like. Part of the conductive layer 453 functions as a first gate of the transistor 450, and part of the conductive layer 455 functions as a second gate of the transistor 450. In this case, part of the insulating layer 452 functions as a first gate insulating layer of the transistor 450, and part of the insulating layer 422 functions as a second gate insulating layer of the transistor 450.

[0581] The conductive layer 455 is provided over the insulating layer 412. The insulating layer 422 is provided to cover the conductive layer 455. The semiconductor layer 451 is provided over the insulating layer 422. The insulating layer 452 is provided to cover the semiconductor layer 451 and the insulating layer 422. The conductive layer 453 is provided over the insulating layer 452 and has a region overlapping with the semiconductor layer 451 and the conductive layer 455.

[0582] An insulating layer 426 is provided to cover the insulating layer 452 and the conductive layer 453. A conductive layer 454a and a conductive layer 454b are provided over the insulating layer 426. The conductive layer 454a and the conductive layer 454b are electrically connected to the semiconductor layer 451 through openings provided in the insulating layer 426 and the insulating layer 452. Part of the conductive layer 454a functions as one of the source and drain electrodes, and part of the conductive layer 454b functions as the other of the source and drain electrodes. An insulating layer 423 is provided to cover the conductive layer 454a, the conductive layer 454b, and the insulating layer 426.

[0583] Here, the conductive layers 414a and 414b electrically connected to the transistor 410a are preferably formed by processing the same conductive film as the conductive layers 454a and 454b. FIG. 31C shows a structure in which the conductive layers 414a, 414b, 454a, and 454b are formed on the same surface (i.e., in contact with the top surface of the insulating layer 426) and contain the same metal element. In this case, the conductive layers 414a and 414b are electrically connected to the low-resistance region 411n through openings provided in the insulating layer 426, the insulating layer 452, the insulating layer 422, and the insulating layer 412. This is preferable because it simplifies the manufacturing process.

[0584] The conductive layer 413 functioning as the first gate electrode of the transistor 410a and the conductive layer 455 functioning as the second gate electrode of the transistor 450 are preferably formed by processing the same conductive film. In Figure 31C, the conductive layer 413 and the conductive layer 455 are formed on the same surface (i.e., in contact with the top surface of the insulating layer 412) and contain the same metal element, which is preferable because it simplifies the manufacturing process.

[0585] In FIG. 31C, the insulating layer 452 functioning as the first gate insulating layer of the transistor 450 covers the end portion of the semiconductor layer 451. However, as in the transistor 450a shown in FIG. 31D, the insulating layer 452 may be processed so that the top surface shape thereof matches or approximately matches the conductive layer 453.

[0586] In this specification, the phrase "top surface shapes generally match" refers to the overlap of at least a portion of the contours between stacked layers. For example, this includes cases where the upper and lower layers are processed using the same mask pattern or a portion of the same mask pattern. However, strictly speaking, the contours may not overlap, and the upper layer may be located inside the lower layer, or outside the lower layer. In these cases, the phrase "top surface shapes generally match" also applies.

[0587] Although the example shown here is one in which the transistor 410a corresponds to the transistor M2 and is electrically connected to the pixel electrode, this is not limiting. For example, the transistor 450 or the transistor 450a may correspond to the transistor M2. In this case, the transistor 410a corresponds to the transistor M1, the transistor M3, or another transistor.

[0588] This embodiment mode can be combined with other embodiment modes as appropriate.

[0589] (Sixth embodiment) In this embodiment, a metal oxide (also referred to as an oxide semiconductor) that can be used for the OS transistor described in the above embodiment will be described.

[0590] The metal oxide preferably contains at least indium or zinc. It is particularly preferable that it contains indium and zinc. It is also preferable that it contains aluminum, gallium, yttrium, tin, or the like in addition to these. It may also contain one or more elements selected from boron, silicon, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, magnesium, cobalt, and the like.

[0591] Furthermore, the metal oxide can be formed by a sputtering method, a chemical vapor deposition (CVD) method such as a metal organic chemical vapor deposition (MOCVD) method, or an atomic layer deposition (ALD) method.

[0592] <Classification of crystal structures> Examples of the crystalline structure of oxide semiconductors include amorphous (including completely amorphous), c-axis-aligned crystalline (CAAC), nanocrystalline (nc), cloud-aligned composite (CAC), single crystal, and polycrystal.

[0593] The crystalline structure of a film or substrate can be evaluated using X-ray diffraction (XRD) spectra. For example, it can be evaluated using XRD spectra obtained by GIXD (Grazing-Incidence XRD) measurements. The GIXD method is also called the thin film method or the Seemann-Bohlin method.

[0594] For example, for a quartz glass substrate, the peak shape of the XRD spectrum is nearly symmetrical. On the other hand, for an IGZO film with a crystalline structure, the peak shape of the XRD spectrum is asymmetrical. The asymmetrical peak shape of the XRD spectrum clearly indicates the presence of crystals in the film or substrate. In other words, if the peak shape of the XRD spectrum is not symmetrical, the film or substrate cannot be said to be in an amorphous state.

[0595] The crystalline structure of a film or substrate can also be evaluated by the diffraction pattern (also called the nanobeam electron diffraction pattern) observed using nanobeam electron diffraction (NBED). For example, a halo is observed in the diffraction pattern of a quartz glass substrate, confirming that the quartz glass is in an amorphous state. Furthermore, a spot-like pattern is observed in the diffraction pattern of an IGZO film deposited at room temperature, rather than a halo. For this reason, it is estimated that an IGZO film deposited at room temperature is neither crystalline nor amorphous, but is in an intermediate state, and it cannot be concluded that it is in an amorphous state.

[0596] <<Oxide semiconductor structure>> Note that oxide semiconductors may be classified differently from the above when focusing on their structures. For example, oxide semiconductors are divided into single-crystal oxide semiconductors and other non-single-crystal oxide semiconductors. Examples of non-single-crystal oxide semiconductors include the above-mentioned CAAC-OS and nc-OS. Non-single-crystal oxide semiconductors include polycrystalline oxide semiconductors, amorphous-like oxide semiconductors (a-like OSs), amorphous oxide semiconductors, and the like.

[0597] Here, the above-mentioned CAAC-OS, nc-OS, and a-like OS will be described in detail.

[0598] [CAAC-OS] CAAC-OS is an oxide semiconductor having multiple crystalline regions, each with its c-axis aligned in a specific direction. The specific direction can be the thickness direction of the CAAC-OS film, the normal direction to the surface on which the CAAC-OS film is formed, or the normal direction to the surface of the CAAC-OS film. A crystalline region is a region with periodic atomic arrangement. If the atomic arrangement is considered as a lattice arrangement, a crystalline region can also be a region with a uniform lattice arrangement. Furthermore, CAAC-OS has a region where multiple crystalline regions are connected in the ab-plane direction, and the region may have distortion. Note that distortion refers to a location where the lattice arrangement changes between a region with a uniform lattice arrangement and a region with a different uniform lattice arrangement in the region where multiple crystalline regions are connected. In other words, CAAC-OS is an oxide semiconductor with a c-axis aligned but no clear orientation in the ab-plane direction.

[0599] Each of the multiple crystalline regions is composed of one or more minute crystals (crystals with a maximum diameter of less than 10 nm). When a crystalline region is composed of one minute crystal, the maximum diameter of the crystalline region is less than 10 nm. When a crystalline region is composed of many minute crystals, the size of the crystalline region may be several tens of nm.

[0600] In an In-M-Zn oxide (wherein M is one or more elements selected from aluminum, gallium, yttrium, tin, titanium, etc.), the CAAC-OS tends to have a layered crystal structure (also referred to as a layered structure) in which a layer containing indium (In) and oxygen (hereinafter referred to as an In layer) and a layer containing M, zinc (Zn), and oxygen (hereinafter referred to as an (M, Zn) layer) are stacked. Note that indium and the element M are mutually substituted. Therefore, the (M, Zn) layer may contain indium. The In layer may contain M. The In layer may contain Zn. The layered structure is observed as a lattice image in a high-resolution transmission electron microscope (TEM) image, for example.

[0601] When the CAAC-OS film is subjected to structural analysis using, for example, an XRD apparatus, a peak indicating c-axis orientation is detected at or near 2θ=31° in out-of-plane XRD measurement using θ / 2θ scan. Note that the position of the peak indicating c-axis orientation (2θ value) may vary depending on the type and composition of the metallic elements constituting the CAAC-OS.

[0602] For example, in the electron diffraction pattern of a CAAC-OS film, multiple bright spots are observed, and the spots are observed at positions that are point-symmetric with respect to the spot of the incident electron beam that has passed through the sample (also called the direct spot).

[0603] When the crystalline region is observed from the specific direction, the lattice arrangement within the crystalline region is basically a hexagonal lattice, but the unit cell is not necessarily a regular hexagon and may be non-regular hexagonal. Furthermore, the distortion may have a pentagonal, heptagonal, or other lattice arrangement. In the CAAC-OS, no clear grain boundaries are observed even near the distortion. This indicates that the formation of grain boundaries is suppressed by the distortion of the lattice arrangement. This is thought to be because the CAAC-OS can tolerate distortion due to the lack of close-packed oxygen atom arrangement in the ab-plane direction and the change in interatomic bond distance caused by metal atom substitution.

[0604] A crystal structure with clear grain boundaries is called polycrystalline. Grain boundaries act as recombination centers, trapping carriers and potentially causing a decrease in the on-state current and field-effect mobility of a transistor. Therefore, CAAC-OS, which lacks clear grain boundaries, is one of the crystalline oxides with a crystal structure suitable for use in the semiconductor layer of a transistor. Zn is preferred for use in CAAC-OS. For example, In-Zn oxide and In-Ga-Zn oxide are suitable because they can suppress the generation of grain boundaries more effectively than In oxide.

[0605] CAAC-OS is an oxide semiconductor with high crystallinity and no clear crystal grain boundaries. Therefore, it can be said that the CAAC-OS is less susceptible to a decrease in electron mobility due to crystal grain boundaries. Furthermore, since the crystallinity of an oxide semiconductor can be reduced by impurities or defects, the CAAC-OS can be said to be an oxide semiconductor with few impurities and defects (such as oxygen vacancies). Therefore, oxide semiconductors with CAAC-OS have stable physical properties. Therefore, oxide semiconductors with CAAC-OS are heat-resistant and highly reliable. Furthermore, the CAAC-OS is stable even under high temperatures (so-called thermal budgets) during the manufacturing process. Therefore, using a CAAC-OS for an OS transistor can increase the flexibility of the manufacturing process.

[0606] [nc-OS] The nc-OS has periodic atomic arrangement in a microscopic region (e.g., a region of 1 nm to 10 nm, particularly a region of 1 nm to 3 nm). In other words, the nc-OS has microcrystalline structures. The size of the microcrystalline structures is, for example, 1 nm to 10 nm, particularly 1 nm to 3 nm, and therefore these microcrystalline structures are also called nanocrystalline structures. Furthermore, the nc-OS exhibits no regularity in the crystal orientation between different nanocrystalline structures. Therefore, the entire film lacks orientation. Therefore, depending on the analytical method, the nc-OS may be indistinguishable from an a-like OS or an amorphous oxide semiconductor. For example, when a structural analysis of an nc-OS film is performed using an XRD apparatus, no peaks indicating crystallinity are detected in out-of-plane XRD measurements using θ / 2θ scanning. Furthermore, when an nc-OS film is subjected to electron diffraction (also known as selected-area electron diffraction) using an electron beam with a probe diameter larger than that of nanocrystalline structures (e.g., 50 nm or larger), a halo-like diffraction pattern is observed. On the other hand, when electron diffraction (also called nanobeam electron diffraction) is performed on an nc-OS film using an electron beam with a probe diameter close to or smaller than the size of the nanocrystals (for example, 1 nm to 30 nm), an electron diffraction pattern can be obtained in which multiple spots are observed within a ring-shaped region centered on the direct spot.

[0607] [a-like OS] The a-like OS is an oxide semiconductor having a structure between the nc-OS and the amorphous oxide semiconductor. The a-like OS has a pore or low-density region. That is, the a-like OS has lower crystallinity than the nc-OS and CAAC-OS. Furthermore, the a-like OS has a higher hydrogen concentration in the film than the nc-OS and CAAC-OS.

[0608] <<Oxide semiconductor structure>> Next, the above-mentioned CAC-OS will be described in detail, which relates to the material composition.

[0609] [CAC-OS] CAC-OS is a material structure in which elements constituting a metal oxide are unevenly distributed in a size range of 0.5 nm to 10 nm, preferably 1 nm to 3 nm, or a similar size range. Hereinafter, a metal oxide in which one or more metal elements are unevenly distributed and the regions containing the metal elements are mixed in a size range of 0.5 nm to 10 nm, preferably 1 nm to 3 nm, or a similar size range, is also referred to as a mosaic or patch state.

[0610] Furthermore, CAC-OS has a mosaic structure in which the material is separated into first and second regions, and the first regions are distributed throughout the film (hereinafter also referred to as a cloud structure). That is, CAC-OS is a composite metal oxide having a structure in which the first and second regions are mixed.

[0611] Here, the atomic ratios of In, Ga, and Zn to the metal elements constituting the CAC-OS in the In-Ga-Zn oxide are represented as [In], [Ga], and [Zn], respectively. For example, in the CAC-OS in the In-Ga-Zn oxide, the first region is a region where [In] is larger than [In] in the CAC-OS composition. The second region is a region where [Ga] is larger than [Ga] in the CAC-OS composition. Alternatively, for example, the first region is a region where [In] is larger than [In] in the second region and [Ga] is smaller than [Ga] in the second region. The second region is a region where [Ga] is larger than [Ga] in the first region and [In] is smaller than [In] in the first region.

[0612] Specifically, the first region is a region whose main component is indium oxide, indium zinc oxide, or the like. The second region is a region whose main component is gallium oxide, gallium zinc oxide, or the like. In other words, the first region can be rephrased as a region whose main component is In. The second region can be rephrased as a region whose main component is Ga.

[0613] It should be noted that there are cases where a clear boundary between the first region and the second region cannot be observed.

[0614] In addition, CAC-OS in In-Ga-Zn oxide refers to a material structure containing In, Ga, Zn, and O, in which some regions primarily composed of Ga and other regions primarily composed of In are randomly arranged in a mosaic pattern. Therefore, it is presumed that CAC-OS has a structure in which metal elements are distributed nonuniformly.

[0615] The CAC-OS can be formed, for example, by a sputtering method without heating the substrate. When the CAC-OS is formed by a sputtering method, one or more of an inert gas (typically argon), oxygen gas, and nitrogen gas may be used as the deposition gas. The lower the flow rate ratio of oxygen gas to the total flow rate of deposition gas during deposition, the better. For example, the flow rate ratio of oxygen gas to the total flow rate of deposition gas during deposition is preferably 0% or more and less than 30%, and more preferably 0% or more and 10% or less.

[0616] Furthermore, for example, in the case of CAC-OS in an In-Ga-Zn oxide, EDX mapping obtained using EDX (Energy Dispersive X-ray spectroscopy) confirms that the CAC-OS has a structure in which a region containing In as a main component (first region) and a region containing Ga as a main component (second region) are unevenly distributed and mixed.

[0617] Here, the first region has higher conductivity than the second region. That is, the flow of carriers through the first region causes the metal oxide to exhibit conductivity. Therefore, the first region is distributed in a cloud-like manner in the metal oxide, thereby achieving a high field-effect mobility (μ).

[0618] On the other hand, the second region has higher insulating properties than the first region. That is, the second region is distributed in the metal oxide, thereby suppressing leakage current.

[0619] Therefore, when CAC-OS is used in a transistor, the conductivity due to the first region and the insulating property due to the second region act complementarily, thereby providing the CAC-OS with a switching function (the ability to turn on / off). In other words, CAC-OS has a conductive function in part of the material and an insulating function in part of the material, and the material as a whole functions as a semiconductor. By separating the conductive function from the insulating function, both functions can be maximized. Therefore, by using CAC-OS in a transistor, a high on-current (I on ), high field-effect mobility (μ), and good switching behavior can be achieved.

[0620] Furthermore, a transistor using CAC-OS has high reliability, making it ideal for various semiconductor devices such as display devices.

[0621] Oxide semiconductors have a variety of structures, each with different characteristics. The oxide semiconductor of one embodiment of the present invention may include two or more of an amorphous oxide semiconductor, a polycrystalline oxide semiconductor, an a-like OS, a CAC-OS, an nc-OS, and a CAAC-OS.

[0622] <Transistors containing oxide semiconductors> Next, a case where the oxide semiconductor is used in a transistor will be described.

[0623] By using the oxide semiconductor for a transistor, a transistor with high field-effect mobility and high reliability can be realized.

[0624] For the transistor, an oxide semiconductor with a low carrier concentration is preferably used. For example, the carrier concentration of the oxide semiconductor is 1×10 17 cm -3 Less than 1 × 10 15 cm -3 or less, more preferably 1 × 10 13 cm -3 Less than or equal to 1×10 11 cm -3 or less, more preferably 1 × 10 10 cm -3 Less than 1 x 10 -9 cm -3 That is all. Note that in order to reduce the carrier concentration of an oxide semiconductor film, the impurity concentration in the oxide semiconductor film may be reduced to reduce the density of defect states. In this specification and the like, a semiconductor having a low impurity concentration and a low density of defect states is referred to as a highly purified intrinsic or substantially highly purified intrinsic oxide semiconductor. Note that an oxide semiconductor having a low carrier concentration may also be referred to as a highly purified intrinsic or substantially highly purified intrinsic oxide semiconductor.

[0625] Furthermore, a highly purified intrinsic or substantially highly purified intrinsic oxide semiconductor film has a low density of defect states, and therefore the density of trap states may also be low.

[0626] Furthermore, charges trapped in the trap states of an oxide semiconductor take a long time to disappear and may behave like fixed charges. Therefore, a transistor in which a channel formation region is formed in an oxide semiconductor with a high density of trap states may have unstable electrical characteristics.

[0627] Therefore, in order to stabilize the electrical characteristics of a transistor, it is effective to reduce the impurity concentration in the oxide semiconductor. Furthermore, in order to reduce the impurity concentration in the oxide semiconductor, it is preferable to also reduce the impurity concentration in the adjacent film. Examples of impurities include hydrogen, nitrogen, alkali metals, alkaline earth metals, iron, nickel, and silicon.

[0628] <Impurities> Here, the influence of each impurity in an oxide semiconductor will be described.

[0629] When an oxide semiconductor contains silicon or carbon, which is one of the Group 14 elements, defect levels are formed in the oxide semiconductor. Therefore, the concentration of silicon or carbon in the oxide semiconductor and the concentration of silicon or carbon near the interface with the oxide semiconductor (concentration obtained by secondary ion mass spectrometry (SIMS)) are calculated to be 2×10 18 atoms / cm 3 Less than or equal to 2 x 10 17 atoms / cm 3 The following applies.

[0630] Furthermore, when an oxide semiconductor contains an alkali metal or alkaline earth metal, defect levels may be formed and carriers may be generated. Therefore, a transistor using an oxide semiconductor containing an alkali metal or alkaline earth metal is likely to have normally-on characteristics. Therefore, when the concentration of the alkali metal or alkaline earth metal in the oxide semiconductor obtained by SIMS is 1×10 18 atoms / cm 3 Less than or equal to 2 x 10 16 atoms / cm 3 Do the following:

[0631] Furthermore, when nitrogen is contained in an oxide semiconductor, electrons serving as carriers are generated, the carrier concentration increases, and the semiconductor is likely to become n-type. As a result, a transistor using an oxide semiconductor containing nitrogen as a semiconductor tends to have normally-on characteristics. Alternatively, when nitrogen is contained in an oxide semiconductor, trap states may be formed. As a result, the electrical characteristics of the transistor may become unstable. For this reason, the nitrogen concentration in the oxide semiconductor obtained by SIMS is set to 5×10 19 atoms / cm 3 Less than 5 x 10 18 atoms / cm 3 Less than or equal to 1×10 18 atoms / cm3 Less than 5 × 10, more preferably 17 atoms / cm 3 Do the following:

[0632] Furthermore, hydrogen contained in an oxide semiconductor may react with oxygen bonded to a metal atom to form water, which may form an oxygen vacancy. When hydrogen enters the oxygen vacancy, electrons serving as carriers may be generated. Furthermore, some of the hydrogen may bond with oxygen bonded to a metal atom to generate electrons serving as carriers. Therefore, a transistor using an oxide semiconductor containing hydrogen is likely to have normally-on characteristics. For this reason, it is preferable to reduce the amount of hydrogen in the oxide semiconductor as much as possible. Specifically, the hydrogen concentration in an oxide semiconductor measured by SIMS is 1×10 20 atoms / cm 3 Less than 1 x 10 19 atoms / cm 3 less than 5 × 10 18 atoms / cm 3 less than 1×10 18 atoms / cm 3 Make it less than.

[0633] When an oxide semiconductor with sufficiently reduced impurities is used for a channel formation region of a transistor, stable electrical characteristics can be obtained.

[0634] This embodiment mode can be combined with other embodiment modes as appropriate.

[0635] (Embodiment 7) In this embodiment, electronic devices of one embodiment of the present invention will be described with reference to FIGS.

[0636] The electronic devices of this embodiment include the display device of one embodiment of the present invention in their display portions. The display device of one embodiment of the present invention can easily achieve high definition and high resolution. Therefore, the display device of one embodiment of the present invention can be used in the display portions of various electronic devices.

[0637] Examples of electronic devices include electronic devices with relatively large screens such as television sets, desktop or notebook personal computers, computer monitors, digital signage, large game machines such as pachinko machines, as well as digital cameras, digital video cameras, digital photo frames, mobile phones, portable game machines, personal digital assistants, and sound playback devices.

[0638] In particular, the display device of one embodiment of the present invention can have high resolution and can therefore be suitably used in electronic devices having a relatively small display area. Examples of such electronic devices include wristwatch-type and bracelet-type information terminals (wearable devices), and head-mounted wearable devices such as VR devices (head-mounted displays), AR glasses-type devices, and MR glasses-type devices.

[0639] The display device of one embodiment of the present invention preferably has an extremely high resolution such as HD (1280 × 720 pixels), FHD (1920 × 1080 pixels), WQHD (2560 × 1440 pixels), WQXGA (2560 × 1600 pixels), 4K (3840 × 2160 pixels), or 8K (7680 × 4320 pixels). A resolution of 4K, 8K, or higher is particularly preferable. Furthermore, the pixel density (resolution) of the display device of one embodiment of the present invention is preferably 100 ppi or higher, preferably 300 ppi or higher, more preferably 500 ppi or higher, more preferably 1000 ppi or higher, more preferably 2000 ppi or higher, more preferably 3000 ppi or higher, more preferably 5000 ppi or higher, and even more preferably 7000 ppi or higher. By using a display device having either or both of high resolution and high definition, it is possible to further enhance the sense of realism and depth in electronic devices for personal use such as portable or home use. Furthermore, the screen ratio (aspect ratio) of the display device of one embodiment of the present invention is not particularly limited. For example, the display device can support various screen ratios such as 1:1 (square), 4:3, 16:9, and 16:10.

[0640] The electronic device of this embodiment may have a sensor (including a function to measure force, displacement, position, velocity, acceleration, angular velocity, rotation speed, distance, light, liquid, magnetism, temperature, chemical substance, sound, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, gradient, vibration, odor, or infrared rays).

[0641] The electronic device of the present embodiment can have various functions, such as a function to display various information (still images, videos, text images, etc.) on a display unit, a touch panel function, a function to display a calendar, date, time, etc., a function to execute various software (programs), a wireless communication function, a function to read out programs or data recorded on a recording medium, etc.

[0642] An example of a wearable device that can be worn on the head will be described using Figures 32A, 32B, 33A, and 33B. These wearable devices have one or both of the functions of displaying AR content and VR content. Note that these wearable devices may also have the function of displaying SR or MR content in addition to AR and VR. By having an electronic device have the function of displaying content such as AR, VR, SR, and MR, it is possible to enhance the user's sense of immersion.

[0643] Electronic device 700A shown in FIG. 32A and electronic device 700B shown in FIG. 32B each have a pair of display panels 751, a pair of housings 721, a communication unit (not shown), a pair of mounting units 723, a control unit (not shown), an imaging unit (not shown), a pair of optical members 753, a frame 757, and a pair of nose pads 758.

[0644] The display device of one embodiment of the present invention can be applied to the display panel 751. Therefore, the electronic device can display images with extremely high resolution.

[0645] Electronic device 700A and electronic device 700B can each project an image displayed on display panel 751 onto display area 756 of optical member 753. Because optical member 753 is translucent, the user can see the image displayed in the display area superimposed on a transmitted image visually recognized through optical member 753. Therefore, electronic device 700A and electronic device 700B are each electronic devices capable of AR display.

[0646] Electronic device 700A and electronic device 700B may be provided with a camera capable of capturing an image in front of them as an imaging unit. Furthermore, electronic device 700A and electronic device 700B may each be provided with an acceleration sensor such as a gyro sensor, thereby detecting the orientation of the user's head and displaying an image corresponding to that orientation in display area 756.

[0647] The communication unit has a wireless communication device, and can supply a video signal, etc. Instead of or in addition to the wireless communication device, a connector to which a cable through which a video signal and a power supply potential are supplied may be provided.

[0648] Furthermore, the electronic device 700A and the electronic device 700B are provided with batteries, which can be charged wirelessly and / or by wire.

[0649] The housing 721 may be provided with a touch sensor module. The touch sensor module has a function of detecting a touch on the outer surface of the housing 721. The touch sensor module can detect a tap operation or a slide operation by the user and perform various processes. For example, a tap operation can perform a process such as pausing or resuming a video, and a slide operation can perform a process such as fast-forwarding or fast-rewinding. Furthermore, providing a touch sensor module on each of the two housings 721 can expand the range of operations.

[0650] Various touch sensors can be used as the touch sensor module. For example, various types of touch sensors can be used, such as a capacitance type, a resistive film type, an infrared type, an electromagnetic induction type, a surface acoustic wave type, and an optical type. In particular, it is preferable to use a capacitance type or an optical type sensor in the touch sensor module.

[0651] When an optical touch sensor is used, a photoelectric conversion device (also called a photoelectric conversion element) can be used as a light receiving device (also called a light receiving element). The active layer of the photoelectric conversion device can be made of either or both of an inorganic semiconductor and an organic semiconductor.

[0652] The electronic device 800A shown in FIG. 33A and the electronic device 800B shown in FIG. 33B each have a pair of display units 820, a housing 821, a communication unit 822, a pair of mounting units 823, a control unit 824, a pair of imaging units 825, and a pair of lenses 832.

[0653] The display device of one embodiment of the present invention can be applied to the display portion 820. Therefore, an electronic device capable of displaying images with extremely high resolution can be provided, which allows a user to feel a high sense of immersion.

[0654] Display unit 820 is provided inside housing 821 at a position that can be viewed through lens 832. Also, by displaying different images on the pair of display units 820, it is possible to perform a three-dimensional display using parallax.

[0655] Electronic device 800A and electronic device 800B can each be said to be electronic devices for VR. A user wearing electronic device 800A or electronic device 800B can view an image displayed on display unit 820 through lens 832.

[0656] It is preferable that electronic device 800A and electronic device 800B each have a mechanism that can adjust the left and right positions of lens 832 and display unit 820 so that they are optimally positioned according to the position of the user's eyes. It is also preferable that electronic device 800A and electronic device 800B each have a mechanism that can adjust the focus by changing the distance between lens 832 and display unit 820.

[0657] The user can wear electronic device 800A or electronic device 800B on the head using wearing unit 823. Note that, although FIG. 33A and other figures illustrate a shape similar to the temples of glasses (also called joints or temples), the shape is not limited to this. Wearing unit 823 may be shaped like a helmet or a band, for example, as long as it can be worn by the user.

[0658] The imaging unit 825 has a function of acquiring external information. Data acquired by the imaging unit 825 can be output to the display unit 820. An image sensor can be used for the imaging unit 825. Furthermore, multiple cameras may be provided to support multiple angles of view, such as telephoto and wide angle.

[0659] Although an example having the imaging unit 825 has been shown here, a distance measuring sensor (hereinafter also referred to as a detection unit) capable of measuring the distance to an object may be provided. That is, the imaging unit 825 is one aspect of the detection unit. As the detection unit, for example, an image sensor or a range image sensor such as a LIDAR (Light Detection and Ranging) can be used. By using an image obtained by the camera and an image obtained by the range image sensor, more information can be obtained, enabling more accurate gesture operations.

[0660] Electronic device 800A may have a vibration mechanism that functions as a bone conduction earphone. For example, a configuration having such a vibration mechanism can be applied to one or more of display unit 820, housing 821, and wearing unit 823. This allows a user to enjoy video and audio simply by wearing electronic device 800A, without the need for separate audio equipment such as headphones, earphones, or speakers.

[0661] The electronic device 800A and the electronic device 800B may each have an input terminal to which a cable can be connected for supplying a video signal from a video output device or the like and power for charging a battery provided in the electronic device.

[0662] The electronic device of one embodiment of the present invention may have a function of wireless communication with earphone 750. Earphone 750 has a communication unit (not shown) and has a wireless communication function. Earphone 750 can receive information (e.g., audio data) from the electronic device through the wireless communication function. For example, electronic device 700A shown in FIG. 32A has a function of transmitting information to earphone 750 through the wireless communication function. Furthermore, electronic device 800A shown in FIG. 33A has a function of transmitting information to earphone 750 through the wireless communication function.

[0663] The electronic device may also have an earphone unit. Electronic device 700B shown in Fig. 32B has earphone unit 727. For example, earphone unit 727 and the control unit may be configured to be connected to each other by wire. Part of the wiring connecting earphone unit 727 and the control unit may be disposed inside housing 721 or wearing unit 723.

[0664] Similarly, electronic device 800B shown in Fig. 33B has earphone unit 827. For example, earphone unit 827 and control unit 824 can be configured to be connected to each other by wire. Part of the wiring connecting earphone unit 827 and control unit 824 may be disposed inside housing 821 or wearing unit 823. Furthermore, earphone unit 827 and wearing unit 823 may have magnets. This allows earphone unit 827 to be fixed to wearing unit 823 by magnetic force, which is preferable as it makes storage easier.

[0665] The electronic device may have an audio output terminal to which earphones or headphones can be connected. The electronic device may also have one or both of an audio input terminal and an audio input mechanism. For example, a sound collection device such as a microphone can be used as the audio input mechanism. By having the audio input mechanism, the electronic device may be endowed with the functionality of a so-called headset.

[0666] As described above, the electronic devices of one embodiment of the present invention are preferably either glasses-type devices (such as the electronic devices 700A and 700B) or goggle-type devices (such as the electronic devices 800A and 800B).

[0667] Furthermore, the electronic device of one embodiment of the present invention can transmit information to the earphone by wire or wirelessly.

[0668] Electronic device 6500 shown in FIG. 34A is a portable information terminal that can be used as a smartphone.

[0669] The electronic device 6500 includes a housing 6501, a display portion 6502, a power button 6503, a button 6504, a speaker 6505, a microphone 6506, a camera 6507, and a light source 6508. The display portion 6502 has a touch panel function.

[0670] The display device of one embodiment of the present invention can be applied to the display portion 6502.

[0671] FIG. 34B is a schematic cross-sectional view including the end of the housing 6501 on the microphone 6506 side.

[0672] A light-transmitting protective member 6510 is provided on the display surface side of the housing 6501, and a display panel 6511, optical members 6512, a touch sensor panel 6513, a printed circuit board 6517, a battery 6518, etc. are arranged in the space surrounded by the housing 6501 and the protective member 6510.

[0673] A display panel 6511, an optical member 6512, and a touch sensor panel 6513 are fixed to the protective member 6510 by adhesive layers (not shown).

[0674] In an area outside the display unit 6502, a part of the display panel 6511 is folded back, and an FPC 6515 is connected to the folded back part. An IC 6516 is mounted on the FPC 6515. The FPC 6515 is connected to a terminal provided on a printed circuit board 6517.

[0675] The flexible display of one embodiment of the present invention can be applied to the display panel 6511. Therefore, an extremely lightweight electronic device can be realized. In addition, since the display panel 6511 is extremely thin, a large-capacity battery 6518 can be mounted thereon while keeping the thickness of the electronic device small. Furthermore, by folding back a part of the display panel 6511 and arranging a connection portion with the FPC 6515 on the back side of the pixel portion, an electronic device with a narrow frame can be realized.

[0676] 35A shows an example of a television device. A television device 7100 has a display unit 7000 built into a housing 7101. Here, the housing 7101 is supported by a stand 7103.

[0677] The display device of one embodiment of the present invention can be applied to the display portion 7000.

[0678] 35A can be operated using operation switches provided on the housing 7101 and a separate remote control 7111. Alternatively, a touch sensor may be provided in the display unit 7000, and the television 7100 may be operated by touching the display unit 7000 with a finger or the like. The remote control 7111 may have a display unit that displays information output from the remote control 7111. The channel and volume can be controlled using operation keys or a touch panel provided on the remote control 7111, and the video displayed on the display unit 7000 can be controlled.

[0679] The television device 7100 is configured to include a receiver, a modem, and the like. The receiver can receive general television broadcasts. In addition, by connecting to a wired or wireless communication network via the modem, it is possible to perform one-way (from sender to receiver) or two-way (between sender and receiver, or between receivers, etc.) information communication.

[0680] 35B shows an example of a laptop personal computer 7200. The laptop personal computer 7200 includes a housing 7211, a keyboard 7212, a pointing device 7213, an external connection port 7214, and the like. A display portion 7000 is incorporated in the housing 7211.

[0681] The display device of one embodiment of the present invention can be applied to the display portion 7000.

[0682] 35C and 35D show an example of digital signage.

[0683] 35C includes a housing 7301, a display unit 7000, and a speaker 7303. The digital signage 7300 may further include an LED lamp, operation keys (including a power switch or an ...

Claims

1. forming a conductive film on the insulating surface; forming a first layer on the conductive film; forming a first sacrificial layer on the first layer; processing the first layer and the first sacrificial layer to expose a portion of the conductive film; forming a second layer on the first sacrificial layer and the conductive film; forming a second sacrificial layer on the second layer; processing the second layer and the second sacrificial layer to expose a portion of the conductive film; forming a first pixel electrode overlapping the first sacrificial layer and a second pixel electrode overlapping the second sacrificial layer by processing the conductive film; forming a first insulating film that covers at least a side surface of the first pixel electrode, a side surface of the second pixel electrode, a side surface of the first layer, a side surface of the second layer, a side surface and an upper surface of the first sacrificial layer, and a side surface and an upper surface of the second sacrificial layer; forming a first insulating layer that covers at least a side surface of the first pixel electrode, a side surface of the second pixel electrode, a side surface of the first layer, and a side surface of the second layer by processing the first insulating film; removing the first sacrificial layer and the second sacrificial layer; A method for manufacturing a display device further comprising forming a common electrode over the first layer and the second layer.

2. forming a conductive film on the insulating surface; forming a first layer on the conductive film; forming a first sacrificial layer on the first layer; processing the first layer and the first sacrificial layer to expose a portion of the conductive film; forming a second layer on the first sacrificial layer and the conductive film; forming a second sacrificial layer on the second layer; processing the second layer and the second sacrificial layer to expose a portion of the conductive film; forming a first pixel electrode overlapping the first sacrificial layer and a second pixel electrode overlapping the second sacrificial layer by processing the conductive film; forming a first insulating film using an inorganic material to cover at least a side surface of the first pixel electrode, a side surface of the second pixel electrode, a side surface of the first layer, a side surface of the second layer, a side surface and an upper surface of the first sacrificial layer, and a side surface and an upper surface of the second sacrificial layer; forming a second insulating film on the first insulating film using an organic material; forming a first insulating layer and a second insulating layer on the first insulating layer, the first insulating layer and the second insulating layer covering at least a side surface of the first pixel electrode, a side surface of the second pixel electrode, a side surface of the first layer, and a side surface of the second layer by processing the first insulating layer and the second insulating layer; removing the first sacrificial layer and the second sacrificial layer; A method for manufacturing a display device further comprising forming a common electrode over the first layer and the second layer.

3. In claim 2, forming a first conductive layer overlapping at least one of the first sacrificial layer and the second sacrificial layer by processing the conductive film; forming the second insulating film so as to have an opening at a position overlapping the first conductive layer; The method for manufacturing a display device further comprises forming the common electrode over the first conductive layer.

4. In claim 2 or 3, The method for manufacturing a display device further comprises forming the second insulating film using a photosensitive resin as the organic material.

5. In claim 3, The method for manufacturing a display device further comprises the steps of: forming the common electrode; and removing at least a part of a region of the common electrode that is outside a region overlapping with the first conductive layer.

6. In any one of claims 1 to 5, forming a first sacrificial film and a second sacrificial film on the first sacrificial film as the first sacrificial layer; forming a first resist mask on the second sacrificial film, and then processing the second sacrificial film using the first resist mask; removing the first resist mask; The first sacrificial film is processed using the processed second sacrificial film as a hard mask; The method for manufacturing a display device further comprises: processing the first layer by using the processed first sacrificial film as a hard mask.

7. In any one of claims 1 to 6, The method for manufacturing a display device further comprises processing the conductive film by using the first sacrificial layer and the second sacrificial layer as a hard mask.

8. In any one of claims 1 to 7, forming a third layer on the first layer and the second layer after removing the first sacrificial layer and the second sacrificial layer; The common electrode is formed over the third layer.

9. In any one of claims 1 to 8, In the step of processing the conductive film, a recess is formed on the insulating surface.

10. In any one of claims 1 to 9, forming a first conductive film having a recess and a second conductive film on the first conductive film; A method for manufacturing a display device, comprising: forming a fourth layer in the recessed portion of the first conductive film; and then forming the second conductive film on the first conductive film and the fourth layer.

11. In claim 10, The fourth layer is formed using an organic material.

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