Display device, display module, electronic device, and method for manufacturing a display device.

Abstract

The present invention provides a highly reliable display device. A display device according to the present invention comprises a first light emitting element, a second light emitting element, a first electrically insulating layer, and a second electrically insulating layer. The first light emitting element has a first pixel electrode, a first EL layer on the first pixel electrode, and a common electrode on the first EL layer. The second light emitting element has a second pixel electrode, a second EL layer on the second pixel electrode, and the common electrode on the second EL layer. The first electrically insulating layer covers a side surface and a part of the upper surface of the first EL layer, and a side surface and a part of the upper surface of the second EL layer. The second electrically insulating layer overlaps a part of the upper surface of the first EL layer and a part of the upper surface of the second EL layer with the first electrically insulating layer therebetween. The second electrically insulating layer has a region that is located between the side surface of the first EL layer and the side surface of the second EL layer, and further has a recessed part at a position that overlaps the region. In the display device, the common electrode is disposed on the second electrically insulating layer.

Description

[Technical Field]

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

[0002] It should be noted that one aspect of the present invention is not limited to the above-mentioned technical field. Examples of technical fields of one aspect of the present invention include semiconductor devices, display devices, light-emitting devices, energy storage devices, memory devices, electronic devices, lighting devices, input devices (e.g., touch sensors), input / output devices (e.g., touch panels), methods for driving them, or methods for manufacturing them. [Background technology]

[0003] In recent years, display devices have been expected to have applications in a variety of uses. For example, large-scale display devices are used in home television systems (also called televisions or television receivers), digital signage, and PID (Public Information Display). Furthermore, development is progressing on mobile information terminals such as smartphones and tablet devices equipped with touch panels.

[0004] Furthermore, there is a demand for higher resolution display devices. Devices requiring high-resolution displays, 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, light-emitting devices (also called light-emitting devices) have been developed. Light-emitting devices (also called EL elements or organic EL elements) that utilize the electroluminescence (EL) phenomenon have features such as being easy to make thin and light, being able to respond quickly to input signals, and being able to be driven using a DC constant voltage power supply, and are being applied to display devices.

[0006] Patent Document 1 discloses a display device for VR using an organic EL element (also called an organic EL device).

[0007] Furthermore, Non-Patent Document 1 discloses a method for manufacturing organic optoelectronic devices using standard UV photolithography. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] International Publication No. 2018 / 087625 [Non-patent literature]

[0009] [Non-Patent Document 1] B. Lamprecht et al., “Organic optoelectronic device fabrication using standard UV photolithography” phys.stat.sol. (RRL) 2, No. 1, p. 16-18 (2008) [Overview of the project] [Problems that the invention aims to solve]

[0010] When stress is applied to the layers that make up a display device, for example, the adhesion between the films may decrease, leading to film delamination. This can reduce the yield of the display device and decrease its reliability.

[0011] Therefore, one aspect of the present invention aims to provide a highly reliable display device. Alternatively, one aspect of the present invention aims to provide a display device with high display quality. Alternatively, one aspect of the present invention aims to provide a high-definition display device. Alternatively, one aspect of the present invention aims to provide a high-resolution display device. Alternatively, one aspect of the present invention aims to provide a novel display device.

[0012] Alternatively, one aspect of the present invention aims to provide a method for manufacturing a display device with a high yield. Alternatively, one aspect of the present invention aims to provide a method for manufacturing a highly reliable display device. Alternatively, one aspect of the present invention aims to provide a method for manufacturing a display device with high display quality. Alternatively, one aspect of the present invention aims to provide a method for manufacturing a high-definition display device. Alternatively, one aspect of the present invention aims to provide a method for manufacturing a high-resolution display device. Alternatively, one aspect of the present invention aims to provide a method for manufacturing a novel display device.

[0013] Furthermore, the description of these problems does not preclude the existence of other problems. One aspect of the present invention does not necessarily have to solve all of these problems. It is possible to extract other problems from the description, drawings, or claims. [Means for solving the problem]

[0014] One aspect of the present invention includes a first light-emitting element, a second light-emitting element, a first insulating layer, and a second insulating layer. The first light-emitting element includes a first pixel electrode, a first EL layer on the first pixel electrode, and a common electrode on the first EL layer. The second light-emitting element includes a second pixel electrode, a second EL layer on the second pixel electrode, and a common electrode on the second EL layer. The first insulating layer covers a part of the upper surface and the side surface of the first EL layer and a part of the upper surface and the side surface of the second EL layer. The second insulating layer overlaps a part of the upper surface of the first EL layer and a part of the upper surface of the second EL layer via the first insulating layer. The second insulating layer has a region located between the side surfaces of the first EL layer and the second EL layer, and the second insulating layer has a concave portion at a position overlapping the region. The common electrode is provided on the second insulating layer. This is a display device.

[0015] Alternatively, in the above aspect, the second insulating layer may have a concave curved surface shape in the concave portion.

[0016] Alternatively, in the above aspect, the minimum height portion in the cross-sectional view of the concave portion may not overlap with either the first EL layer or the second EL layer.

[0017] Alternatively, in the above aspect, the first EL layer includes a first light-emitting layer and a first functional layer on the first light-emitting layer, the second EL layer includes a second light-emitting layer and a second functional layer on the second light-emitting layer, and each of the first functional layer and the second functional layer may have at least one of a hole injection layer, an electron injection layer, a hole transport layer, an electron transport layer, a hole blocking layer, and an electron blocking layer.

[0018] Alternatively, in the above aspect, the second insulating layer may cover at least a part of the side surface of the first insulating layer.

[0019] Alternatively, in the above aspect, the end portion of the second insulating layer may be located outside the end portion of the first insulating layer.

[0020] Alternatively, in the above aspect, in a cross-sectional view, the end of the first insulating layer and the end of the second insulating layer may have a tapered shape with a taper angle of less than 90°.

[0021] Alternatively, in the above aspect, it has a third insulating layer and a fourth insulating layer. The third insulating layer is located between the upper surface of the first EL layer and the first insulating layer, and the fourth insulating layer is located between the upper surface of the second EL layer and the first insulating layer. The ends of the third insulating layer and the ends of the fourth insulating layer may be located outside the ends of the first insulating layer, respectively.

[0022] Alternatively, in the above aspect, the second insulating layer may cover at least a part of the side surface of the third insulating layer and at least a part of the side surface of the fourth insulating layer.

[0023] Alternatively, in the above aspect, in a cross-sectional view, the ends of the third insulating layer and the ends of the fourth insulating layer may each have a tapered shape with a taper angle of less than 90°.

[0024] Alternatively, in the above aspect, the first insulating layer may be an inorganic insulating layer, and the second insulating layer may be an organic insulating layer.

[0025] A display module having at least one of the display device according to one aspect of the present invention, a connector, and an integrated circuit is also one aspect of the present invention.

[0026] Furthermore, an electronic device having at least one of the display module according to one aspect of the present invention, a housing, a battery, a camera, a speaker, and a microphone is also one aspect of the present invention.

[0027] Alternatively, in one aspect of the present invention, a first pixel electrode and a second pixel electrode are formed, a first EL film is formed on the first pixel electrode and on the second pixel electrode, a first mask film is formed on the first EL film, the first EL film and the first mask film are processed to form a first EL layer on the first pixel electrode and a first mask layer on the first EL layer, a second EL film is formed on the first mask layer and on the second pixel electrode, and a second mask film is formed on the second EL film. The first EL film and the second mask film are processed to form a second EL layer on the second pixel electrode and a second mask layer on the second EL layer. An inorganic insulating film is formed on the first mask layer and the second mask layer. An organic insulating film is formed on the inorganic insulating film using a photosensitive material. A first exposure and first development are performed on the organic insulating film to form an organic insulating layer in the region located between the side surface of the first EL layer and the side surface of the second EL layer. This is a method for manufacturing a display device, in which a first etching treatment is performed on an inorganic insulating film using an organic insulating layer as a mask, the thickness of a portion of the inorganic insulating film is thinned, a second exposure is performed on the organic insulating layer, a second development is performed on the organic insulating layer using a second chemical solution that functions as a developer, and a second etching treatment is performed on the inorganic insulating film, the first mask layer, and the second mask layer using the organic insulating layer as a mask, thereby forming recesses in the area overlapping with the organic insulating layer and forming an inorganic insulating layer beneath the organic insulating layer, further thinning the thickness of a portion of the first mask layer and a portion of the second mask layer, heat treatment is performed to harden the organic insulating layer, and a third etching treatment is performed on the first mask layer and the second mask layer using a third chemical solution, using the organic insulating layer as a mask, exposing the upper surfaces of the first EL layer and the second EL layer, and common electrodes are formed on the first EL layer, the second EL layer, and the organic insulating layer.

[0028] Alternatively, in the above embodiment, the energy density of the second exposure may be lower than the energy density of the first exposure.

[0029] Alternatively, in the above embodiment, the first chemical solution may function as a developer.

[0030] Alternatively, in the above embodiment, the first chemical solution and the third chemical solution may function as a developer.

[0031] Alternatively, in the above embodiment, the first mask film and the second mask film may contain the same material as the inorganic insulating film.

[0032] Alternatively, in the above embodiment, the first mask film, the second mask film, and the inorganic insulating film may each be formed using the ALD method.

[0033] Alternatively, in the above embodiment, a first EL film may be formed comprising a first light-emitting film and a first functional film on the first light-emitting film, and a second EL film may be formed comprising a second light-emitting film and a second functional film on the second light-emitting film, wherein the first functional film and the second functional film may each have at least one of the films that are hole injection layers, electron injection layers, hole transport layers, electron transport layers, hole blocking layers, and electron blocking layers. [Effects of the Invention]

[0034] According to one aspect of the present invention, a highly reliable display device can be provided. Alternatively, according to one aspect of the present invention, a display device with high display quality can be provided. Alternatively, according to one aspect of the present invention, a high-definition display device can be provided. Alternatively, according to one aspect of the present invention, a high-resolution display device can be provided. Alternatively, according to one aspect of the present invention, a novel display device can be provided.

[0035] Alternatively, according to one aspect of the present invention, a method for manufacturing a display device with a high yield can be provided. Alternatively, according to one aspect of the present invention, a method for manufacturing a display device with high reliability can be provided. Alternatively, according to one aspect of the present invention, a method for manufacturing a display device with high display quality can be provided. Alternatively, according to one aspect of the present invention, a method for manufacturing a high-definition display device can be provided. Alternatively, according to one aspect of the present invention, a method for manufacturing a high-resolution display device can be provided. Alternatively, according to one aspect of the present invention, a method for manufacturing a novel display device can be provided.

[0036] Furthermore, the description of these effects does not preclude the existence of other effects. One aspect of the present invention does not necessarily have to possess all of these effects. Other effects can be extracted from the description, drawings, or claims. [Brief explanation of the drawing]

[0037] Figure 1 is a plan view showing an example of the configuration of a display device. Figure 2 is a cross-sectional view showing an example of the configuration of a display device. Figures 3A and 3B are cross-sectional views showing examples of the configuration of a display device. Figures 4A and 4B are cross-sectional views showing examples of the configuration of a display device. Figures 5A and 5B are cross-sectional views showing examples of the configuration of a display device. Figures 6A and 6B are cross-sectional views showing examples of the configuration of a display device. Figures 7A and 7B are cross-sectional views showing examples of the configuration of a display device. Figures 8A and 8B are cross-sectional views showing examples of the configuration of a display device. Figure 9 is a cross-sectional view showing an example of the configuration of a display device. Figures 10A to 10D are cross-sectional views showing examples of methods for manufacturing a display device. Figures 11A to 11D are cross-sectional views showing examples of methods for manufacturing a display device. Figures 12A to 12C are cross-sectional views showing examples of methods for manufacturing a display device. Figures 13A, 13B1, and 13B2 are cross-sectional views showing examples of methods for manufacturing a display device. Figures 14A1, 14A2, and 14B are cross-sectional views showing examples of methods for manufacturing a display device. Figures 15A1, 15A2, and 15B are cross-sectional views showing examples of methods for manufacturing a display device. Figures 16A and 16B are cross-sectional views showing examples of methods for manufacturing a display device. Figures 17A and 17B are cross-sectional views showing examples of methods for manufacturing a display device. Figures 18A and 18B are cross-sectional views showing examples of methods for manufacturing a display device. Figures 19A to 19C are cross-sectional views showing examples of methods for manufacturing a display device. Figures 20A to 20G are plan views showing examples of pixel configurations. Figures 21A to 21H are plan views showing examples of pixel configurations. Figures 22A and 22B are perspective views showing examples of the display module configuration. Figures 23A and 23B are cross-sectional views showing examples of the configuration of a display device. Figure 24 is a cross-sectional view showing an example of the configuration of a display device. Figure 25 is a cross-sectional view showing an example of the configuration of a display device. Figure 26 is a cross-sectional view showing an example of the configuration of a display device. Figure 27 is a cross-sectional view showing an example of the configuration of a display device. Figure 28 is a cross-sectional view showing an example of the configuration of a display device. Figure 29 is a perspective view showing an example of a display device configuration. Figure 30A is a cross-sectional view showing an example of the configuration of a display device. Figures 30B and 30C are cross-sectional views showing an example of the configuration of a transistor. Figures 31A to 31D are cross-sectional views showing examples of the configuration of a display device. Figure 32 is a cross-sectional view showing an example of the configuration of a display device. Figure 33 is a cross-sectional view showing an example of the configuration of a display device. Figures 34A to 34F are cross-sectional views showing examples of the configuration of a light-emitting element. Figures 35A to 35D show examples of electronic devices. Figures 36A to 36F show examples of electronic devices. Figures 37A to 37G show examples of electronic devices. [Modes for carrying out the invention]

[0038] Embodiments will be described in detail with reference to the drawings. However, it will be readily apparent to those skilled in the art that the present invention is not limited to the following description, and that its form and details can be modified in various ways without departing from the spirit and scope of the present invention. Therefore, the present invention shall not be construed as being limited to the descriptions of the embodiments shown below.

[0039] In the invention described below, the same reference numerals are used in common across different drawings for identical parts or parts having similar functions, and repeated explanations are omitted. Furthermore, when referring to similar functions, the same hatching pattern may be used, and reference numerals may not be assigned.

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

[0041] In this specification, terms such as "above," "below," "upward," or "downward" are used for convenience to explain the positional relationships between components with reference to the drawings. Furthermore, the positional relationships between components change as appropriate depending on the direction in which each component is depicted. Therefore, the terms used are not limited to those explained in this specification and can be appropriately rephrased depending on the situation. For example, the expression "insulating layer located above the conductive layer" can be rephrased as "insulating layer located below the conductive layer" by rotating the orientation of the drawing shown by 180 degrees.

[0042] The terms "film" and "layer" can be interchanged depending on the context or situation. For example, the term "conductive layer" may be changed to "conductive film." Or, for example, the term "insulating film" may be changed to "insulating layer."

[0043] In this specification, devices fabricated using a metal mask or an FMM (Fine Metal Mask, a high-resolution metal mask) may be referred to as MM (Metal Mask) structured devices. Furthermore, in this specification, devices fabricated without using a metal mask or FMM may be referred to as MML (Metal Maskless) structured devices.

[0044] In this specification, holes or electrons may be referred to as "carriers." Specifically, a hole injection layer or electron injection layer may be called a "carrier injection layer," a hole transport layer or electron transport layer may be called a "carrier transport layer," and a hole block layer or electron block layer may be called a "carrier block layer." Note that the above-mentioned carrier injection layer, carrier transport layer, and carrier block layer may not be clearly distinguishable by their cross-sectional shape or characteristics. Furthermore, a single layer may combine the functions of two or three of the carrier injection layer, carrier transport layer, and carrier block layer.

[0045] In this specification, a light-emitting device has an EL layer between a pair of electrodes. The EL layer has at least a light-emitting layer. Examples of layers in the EL layer include a light-emitting layer, a carrier injection layer (hole injection layer and electron injection layer), a carrier transport layer (hole transport layer and electron transport layer), and a carrier block layer (hole block layer and electron block layer).

[0046] In this specification, a tapered shape refers to a shape in which at least a portion of the side surface of a structure is inclined with respect to the substrate surface. For example, it refers to a shape having a region where the angle between the inclined side surface and the substrate surface (also called the taper angle) is less than 90°. The side surface of the structure and the substrate surface do not necessarily have to be perfectly flat; they may be substantially planar with a fine curvature, or substantially planar with fine irregularities.

[0047] (Embodiment 1) This embodiment describes a display device according to one aspect of the present invention and a method for manufacturing the same.

[0048] A display device according to one aspect of the present invention is capable of full-color display. For example, a display device capable of full-color display can be manufactured by creating separate EL layers, each having at least an emissive layer, for each emissive color. Alternatively, a display device capable of full-color display can be manufactured by providing a colored layer (also called a color filter) on an EL layer that emits white light, for example.

[0049] In this specification, a structure in which different light-emitting layers are created or painted for each color of light-emitting element (e.g., blue (B), green (G), and red (R)) may be referred to as an SBS (Side By Side) structure. Furthermore, a light-emitting element capable of emitting white light may be referred to as a white light-emitting element.

[0050] When manufacturing a display device having multiple light-emitting elements, each with a different emission color, it is necessary to form the light-emitting layers of each different color in an island-like configuration. Furthermore, even when manufacturing a display device with a white light-emitting element, forming the light-emitting layers in an island-like configuration is preferable because it reduces the leakage current that may occur between adjacent light-emitting elements via the light-emitting layers.

[0051] In this specification, "island-like" refers to a state in which two or more layers made of the same material and formed in the same process are physically separated. For example, an island-like light-emitting layer refers to a state in which the light-emitting layer and an adjacent light-emitting layer are physically separated.

[0052] For example, island-shaped light-emitting layers can be formed using a vacuum deposition method with a metal mask. However, with this method, deviations from the design occur in the shape and position of the island-shaped light-emitting layers due to various factors such as the precision of the metal mask, misalignment between the metal mask and the substrate, deflection of the metal mask, and the spreading of the contour of the deposited film due to vapor scattering, making it difficult to achieve high resolution and high aperture ratio in display devices. In addition, the contour of the layer may become blurred during deposition, and the thickness at the edges may become thinner. In other words, the thickness of the island-shaped light-emitting layer may vary depending on the location. Furthermore, when manufacturing large, high-resolution, or high-definition display devices, there is a concern that the low dimensional accuracy of the metal mask and deformation due to heat, etc., may lead to low manufacturing yield.

[0053] Therefore, when manufacturing a display device according to one aspect of the present invention, the light-emitting layer is processed into a fine pattern by photolithography without using a shadow mask such as a metal mask. Specifically, after forming a pixel electrode for each sub-pixel, a light-emitting layer is deposited across multiple pixel electrodes. Subsequently, the light-emitting layer is processed using photolithography to form one island-shaped light-emitting layer for each pixel electrode. This divides the light-emitting layer for each sub-pixel, allowing for the formation of an island-shaped light-emitting layer for each sub-pixel.

[0054] When processing the above-mentioned light-emitting layer into an island shape, a structure in which the processing is performed using photolithography directly above the light-emitting layer is conceivable. In this structure, the light-emitting layer may be damaged, for example, by processing, and its reliability may be significantly impaired. Therefore, when manufacturing a display device according to one aspect of the present invention, it is preferable to use a method in which, in addition to the light-emitting layer as an EL layer, a mask layer (also called a sacrificial layer or protective layer, etc.) is formed on a functional layer located above the light-emitting layer (for example, a carrier block layer, a carrier transport layer, or a carrier injection layer, more specifically a hole block layer, an electron transport layer, or an electron injection layer, etc.), and the light-emitting layer and the functional layer are processed into an island shape. By applying this method, a highly reliable display device can be provided. By having a functional layer between the light-emitting layer and the mask layer, the exposure of the light-emitting layer to the outermost surface during the manufacturing process of the display device can be suppressed, and the damage to the light-emitting layer can be reduced.

[0055] In this specification, the mask film (also referred to as a sacrificial film or protective film, etc.) and the mask layer are each located above at least the light-emitting layer (more specifically, the layer that is processed into an island shape among the layers constituting the EL layer) and have the function of protecting the light-emitting layer during the manufacturing process.

[0056] The EL layer may have functional layers not only above the light-emitting layer but also below it. When the light-emitting layer is processed into an island shape, it is preferable to process the functional layers located below the light-emitting layer (for example, a carrier injection layer, a carrier transport layer, or a carrier block layer, more specifically a hole injection layer, a hole transport layer, or an electron block layer, etc.) into an island shape using the same pattern as the light-emitting layer. By processing the layers located below the light-emitting layer into an island shape using the same pattern as the light-emitting layer, it is possible to reduce the leakage current (sometimes called lateral leakage current, transverse leakage current, or lateral leakage current) that may occur between adjacent subpixels. For example, when a hole injection layer is used in common between adjacent subpixels, a transverse leakage current may occur due to the hole injection layer. On the other hand, in a display device according to one aspect of the present invention, since the hole injection layer can be processed into an island shape using the same pattern as the light-emitting layer, the transverse leakage current between adjacent subpixels is substantially eliminated or can be made extremely small.

[0057] In this configuration, it is preferable that the EL layer be provided so as to cover the top and side surfaces of the pixel electrodes. This makes it easier to increase the aperture ratio compared to a configuration where the edges of the EL layer are located inside the edges of the pixel electrodes.

[0058] Furthermore, in light-emitting elements that emit different colors, it is not necessary to fabricate all the layers constituting the EL layer separately; some layers can be formed in the same process. In a method for manufacturing a display device according to one aspect of the present invention, some of the layers constituting the EL layer are formed in island-like structures for each color, then at least a portion of the mask layer is removed, and the remaining layers constituting the EL layer (sometimes called common layers) and a common electrode (also called an upper electrode) are formed in common for each color (as a single film). For example, the carrier injection layer and the common electrode can be formed in common for each color.

[0059] On the other hand, the carrier injection layer is often a relatively conductive layer within the EL layer. Therefore, if the carrier injection layer comes into contact with the side surface of some of the island-shaped EL layers, or with the side surface of the pixel electrode, there is a risk of the light-emitting element short-circuiting. Furthermore, even when the carrier injection layer is provided in an island shape and a common electrode is formed in common for each color, there is a risk of the light-emitting element short-circuiting if the common electrode comes into contact with the side surface of the EL layer, or with the side surface of the pixel electrode.

[0060] Therefore, a display device according to one aspect of the present invention has an insulating layer between adjacent light-emitting elements. Specifically, it is preferable that a display device according to one aspect of the present invention has an inorganic insulating layer covering the side surfaces of the island-shaped EL layer and the upper and side surfaces of the mask layer on the EL layer, and that an organic insulating layer is provided on the inorganic insulating layer.

[0061] As a result, contact between at least a portion of the island-shaped EL layer and the pixel electrodes and the carrier injection layer or common electrode can be suppressed. Therefore, short circuits in the light-emitting element can be suppressed and the reliability of the light-emitting element can be improved.

[0062] Here, for example, if the organic insulating layer has a convex curved shape, stress, specifically compressive stress, may be applied to the edges of the organic insulating layer. This can reduce the adhesion between the layer in contact with the organic insulating layer and other layers, potentially causing delamination. For example, the adhesion between the EL layer, which includes the light-emitting layer, and the mask layer may decrease, causing delamination between the EL layer and the mask layer. Consequently, the yield of the display device may decrease, and the manufacturing cost of the display device may increase. Furthermore, the reliability of the display device may decrease.

[0063] Therefore, in one embodiment of the present invention, a recess is provided in the organic insulating layer. For example, a recess is provided in the central part of the organic insulating layer in a cross-sectional view. This relieves local stress that occurs at the edges of the organic insulating layer, and suppresses, for example, the peeling of the film. As a result, defects in the display device can be suppressed, and the display device according to one embodiment of the present invention can be a highly reliable display device. Furthermore, the display device according to one embodiment of the present invention can be manufactured using a method with a high yield.

[0064] The organic insulating layer may have a photosensitive material. In this case, to form an organic insulating layer having recesses, first, an inorganic insulating film that will become the inorganic insulating layer is formed, and then a photosensitive material is applied on the inorganic insulating film. Subsequently, the photosensitive material is subjected to a first exposure and a first development to form an organic insulating layer without recesses between adjacent light-emitting elements. Subsequently, the organic insulating layer without recesses is subjected to a second exposure and a second development to form recesses in the organic insulating layer. By making the energy density of the second exposure lower than the energy density of the first exposure, it is possible to prevent the organic insulating layer from disappearing and breaking apart in the exposed area during the second exposure.

[0065] After forming the organic insulating layer, the inorganic insulating film and the mask layer are processed using the organic insulating layer as a mask. This allows the inorganic insulating layer beneath the organic insulating layer to be formed, and at least a portion of the mask layer to be removed, exposing the upper surface of the EL layer. Subsequently, a common layer and a common electrode are formed. As a result, a light-emitting element having a pixel electrode, an EL layer, a common layer, and a common electrode can be formed.

[0066] The inorganic insulating film and mask layer are preferably processed by a wet etching method. By using a wet etching method, damage to the EL layer can be reduced compared to when a dry etching method is used. Here, for example, if the mask layer has an inorganic insulating material, the wet etching of the inorganic insulating film and mask layer can be performed using a developer. Therefore, the inorganic insulating film and mask layer can be processed using the same chemicals as those used for the first and second development described above.

[0067] In this case, the formation of recesses in the organic insulating layer by the second development and the processing of, for example, an inorganic insulating film are carried out in parallel. In other words, the formation of recesses in the organic insulating layer by the second development and the processing of, for example, an inorganic insulating film are carried out simultaneously or combined into the same process. Here, if the time for the second development is too short, the removal of the inorganic insulating film will be insufficient. On the other hand, if the time for the second development is too long, the recesses in the organic insulating layer will become deeper, which may cause connection problems due to step breaks in the common layer and common electrode provided on the organic insulating layer, or an increase in electrical resistance due to localized thinning.

[0068] In this specification, "step breakage" refers to the phenomenon in which a layer, film, or electrode is divided due to the shape of the surface on which it is formed (e.g., a step or unevenness).

[0069] Therefore, in a method for manufacturing a display device according to one aspect of the present invention, after forming an organic insulating layer without recesses by a first development, and before the second exposure, a wet etching treatment is performed on the inorganic insulating film using a developer, with the organic insulating layer as a mask. This thins the film thickness of a portion of the inorganic insulating film. On the other hand, since it is before the second exposure, the organic insulating layer is not processed, and therefore no recesses are formed in the organic insulating layer.

[0070] As a result, the inorganic insulating film can be sufficiently removed even if the second development time is shortened. Therefore, the deepening of the depressions in the organic insulating layer can be suppressed, and the occurrence of defects can be suppressed. Thus, the method for manufacturing a display device according to one embodiment of the present invention can be a manufacturing method with a high yield. Note that the second development may process not only the inorganic insulating film but also the mask layer. For example, the second development may thin a portion of the mask layer.

[0071] After the second development, a heat treatment is performed to harden the organic insulating layer. Then, a wet etching treatment is performed on the mask layer using the organic insulating layer as a mask. This removes at least a portion of the mask layer, exposing the upper surface of the EL layer. Here, since the organic insulating layer is hardened by the heat treatment, even if a developer is used in the wet etching treatment of the mask layer, the organic insulating layer is not processed. Therefore, by performing the above heat treatment, it is possible to prevent, for example, the deepening of depressions in the organic insulating layer due to the above wet etching treatment.

[0072] Subsequently, a common layer and a common electrode are formed. This completes the formation of a light-emitting element having a pixel electrode, an EL layer, a common layer, and a common electrode.

[0073] Furthermore, in cross-sectional view, it is preferable that the edges of the organic insulating layer have a tapered shape with a taper angle of less than 90°. This prevents step breaks in the common layer and common electrode provided on the organic insulating layer. Therefore, connection failures due to step breaks can be suppressed. In addition, it is possible to suppress the local thinning of the common electrode due to the step, which would increase electrical resistance.

[0074] Thus, the island-shaped light-emitting layer produced by the method for manufacturing a display device according to one aspect of the present invention is not formed using a fine metal mask, but rather by processing after the light-emitting layer has been deposited on one surface. 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 light-emitting layer can be made separately for each color, it is possible to realize a display device that is extremely vivid, has high contrast, and has high display quality. In addition, by providing a mask layer on the light-emitting layer, the damage that the light-emitting layer receives during the manufacturing process of the display device can be reduced, and the reliability of the light-emitting element can be improved.

[0075] Furthermore, regarding the distance between adjacent light-emitting elements, for example, it is difficult to reduce it to less than 10 μm using a formation method that uses a fine metal mask. However, according to a photolithography method in one aspect of the present invention, in a process on a glass substrate, the distance between adjacent light-emitting elements, the distance between adjacent EL layers, or the distance between adjacent pixel electrodes can be reduced to less than 10 μm, 5 μm or less, 3 μm or less, 2 μm or less, 1.5 μm or less, 1 μm or less, or 0.5 μm or less. Moreover, by using an exposure apparatus for LSIs, for example, in a process on a Si Wafer, the distance between adjacent light-emitting elements, the distance between adjacent EL layers, or the distance between adjacent pixel electrodes can be reduced to, for example, 500 nm or less, 200 nm or less, 100 nm or less, and even 50 nm or less. This significantly reduces the area of ​​the non-emitting region that may exist between two light-emitting elements, making it possible to bring the aperture ratio closer to 100%. For example, in a display device according to one aspect of the present invention, the aperture ratio can be 40% or more, 50% or more, 60% or more, 70% or more, 80% or more, and even 90% or more, while achieving less than 100%.

[0076] Furthermore, increasing the aperture ratio of a display device can improve its reliability. More specifically, using an organic EL element and taking the lifespan of a display device with an aperture ratio of 10% as a baseline, a display device with an aperture ratio of 20% (i.e., twice the aperture ratio of the baseline) will have a lifespan approximately 3.25 times longer, and a display device with an aperture ratio of 40% (i.e., four times the aperture ratio of the baseline) will have a lifespan approximately 10.6 times longer. Thus, as the aperture ratio is increased, the current density flowing through the organic EL element can be reduced, making it possible to improve the lifespan of the display device. In one embodiment of the present invention, since the aperture ratio can be increased, the display quality of the display device can be improved. Moreover, as the aperture ratio of the display device is increased, the reliability (especially the lifespan) of the display device is significantly improved, which is a great effect.

[0077] Furthermore, the pattern of the light-emitting layer itself can be made extremely small compared to when a fine metal mask is used. Also, for example, when a metal mask is used to create different types of light-emitting layers, variations in thickness occur between the center and edges of the pattern, so the effective area that can be used as a light-emitting region is small relative to the total area of ​​the pattern. On the other hand, with the above manufacturing method, since a film deposited to a uniform thickness is processed, island-shaped light-emitting 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. As a result, it is possible to manufacture a display device that combines high resolution and a high aperture ratio. Furthermore, it is possible to achieve miniaturization and weight reduction of the display device.

[0078] Specifically, a display device according to one aspect of the present invention may have a resolution of, for example, 2000 ppi or more, preferably 3000 ppi or more, more preferably 5000 ppi or more, and even more preferably 6000 ppi or more, and may be 20000 ppi or less, or 30000 ppi or less.

[0079] [Configuration Example 1] Figure 1 is a plan view showing an example configuration of the display device 100. The display device 100 has a pixel section 107 in which a plurality of pixels 108 are arranged in a matrix. The pixels 108 include sub-pixels 110R, sub-pixels 110G, and sub-pixels 110B. In Figure 1, two rows and six columns of sub-pixels 110 are shown, and these constitute two rows and two columns of pixels 108. Note that a plan view can sometimes be called a top view.

[0080] In this specification, for example, when describing matters common to sub-pixels 110R, 110G, and 110B, they may be referred to simply as sub-pixel 110. Similarly, when describing matters common to other components distinguished by letters, the letters may be omitted and the corresponding symbols used.

[0081] Sub-pixel 110R emits red light, sub-pixel 110G emits green light, and sub-pixel 110B emits blue light. This allows an image to be displayed on the pixel unit 107. Therefore, the pixel unit 107 can be called a display unit. In this embodiment, three sub-pixels of red (R), green (G), and blue (B) are used as an example, but three sub-pixels of yellow (Y), cyan (C), and magenta (M) may also be used. Furthermore, the number of sub-pixel types is not limited to three, but may be four or more. Examples of four sub-pixels include four sub-pixels of R, G, B, and white (W), four sub-pixels of R, G, B, and Y, and four sub-pixels of R, G, B, and infrared (IR).

[0082] Furthermore, it can be said that a stripe array is applied to pixel 108 shown in Figure 1. Note that the array method that can be applied to pixel 108 is not limited to this; other array methods such as stripe arrays, S-stripe arrays, delta arrays, Bayer arrays, or zigzag arrays may also be applied, as well as pentile arrays or diamond arrays.

[0083] In this specification and other documents, the row direction is sometimes referred to as the X direction, and the column direction as the Y direction. The X and Y directions intersect, for example, perpendicularly.

[0084] Figure 1 shows an example where subpixels of different colors are arranged in the X direction and subpixels of the same color are arranged in the Y direction. Alternatively, subpixels of different colors may be arranged in the Y direction and subpixels of the same color may be arranged in the X direction.

[0085] A region 141 and a connecting portion 140 are provided on the outside of the pixel portion 107, with the region 141 located between the pixel portion 107 and the connecting portion 140. An EL layer 113 is provided in the region 141. A conductive layer 123 is provided in the connecting portion 140.

[0086] Figure 1 shows an example where, in a plan view, region 141 and connecting portion 140 are located to the right of the pixel portion 107, but the positions of region 141 and connecting portion 140 are not particularly limited. Region 141 and connecting portion 140 only need to be provided in at least one location on the upper, right, left, or lower side of the pixel portion 107 in a plan view, and may be provided so as to surround all four sides of the pixel portion 107. The upper surface shape of region 141 and connecting portion 140 can be a strip, L-shape, U-shape, or frame shape, etc. Also, there may be one region 141 and multiple connecting portions 140. Note that a plan view may sometimes be referred to as a top view.

[0087] Figure 2 is a cross-sectional view between the dashed line A1-A2 in Figure 1, and is a cross-sectional view showing an example of the configuration of a pixel 108 provided in the pixel section 107. As shown in Figure 2, the display device 100 has an insulating layer 101, a conductive layer 102 on the insulating layer 101, an insulating layer 103 on the insulating layer 101 and on the conductive layer 102, an insulating layer 104 on the insulating layer 103, and an insulating layer 105 on the insulating layer 104. The insulating layer 101 is provided on a substrate (not shown). The insulating layer 105, insulating layer 104, and insulating layer 103 are provided with openings that reach the conductive layer 102, and plugs 106 are provided to fill these openings.

[0088] In the pixel section 107, light-emitting elements 130 are provided on the insulating layer 105 and on the plug 106. A protective layer 131 is provided to cover the light-emitting elements 130. The substrate 120 is bonded to the protective layer 131 by a resin layer 122. In addition, an insulating layer 125 and an insulating layer 127 on the insulating layer 125 are provided between adjacent light-emitting elements 130.

[0089] In Figure 2, multiple cross-sections of the insulating layer 125 and insulating layer 127 are shown, but when the display device 100 is viewed from above, the insulating layer 125 and insulating layer 127 are connected as one unit each. In other words, the display device 100 can be configured to have, for example, one insulating layer 125 and one insulating layer 127. The display device 100 may also have multiple insulating layers 125 that are separated from each other, or multiple insulating layers 127 that are separated from each other.

[0090] In Figure 2, the light-emitting element 130 is shown as light-emitting element 130R, light-emitting element 130G, and light-emitting element 130B. Light-emitting elements 130R, 130G, and 130B emit light of different colors from each other. For example, light-emitting element 130R can emit red light, light-emitting element 130G can emit green light, and light-emitting element 130B can emit blue light. In addition, light-emitting elements 130R, 130G, or 130B may emit light of cyan, magenta, yellow, white, or infrared, etc.

[0091] A display device according to one aspect of the present invention may be any of the following: a top emission type that emits light in the direction opposite to the substrate on which the light-emitting element 130 is formed; a bottom emission type that emits light toward the substrate on which the light-emitting element 130 is formed; or a dual emission type that emits light on both sides.

[0092] As the light-emitting element 130, it is preferable to use, for example, an OLED (Organic Light Emitting Diode) or a QLED (Quantum-dot Light Emitting Diode). Examples of light-emitting materials for the light-emitting element 130 include fluorescent materials, phosphorescent materials, inorganic compounds (e.g., quantum dot materials), and thermally activated delayed fluorescence (TADF) materials. Alternatively, an LED such as a microLED (Light Emitting Diode) can be used as the light-emitting element 130.

[0093] The light-emitting element 130R includes a pixel electrode 111R on the plug 106 and on the insulating layer 105, an EL layer 113R covering the top and sides of the pixel electrode 111R, a common layer 114 on the EL layer 113R, and a common electrode 115 on the common layer 114. In the light-emitting element 130R, the EL layer 113R and the common layer 114 can be collectively referred to as the EL layer.

[0094] The light-emitting element 130G includes a pixel electrode 111G on the plug 106 and on the insulating layer 105, an EL layer 113G covering the top and sides of the pixel electrode 111G, a common layer 114 on the EL layer 113G, and a common electrode 115 on the common layer 114. In the light-emitting element 130G, the EL layer 113G and the common layer 114 can be collectively referred to as the EL layer.

[0095] The light-emitting element 130B includes a pixel electrode 111B on the plug 106 and on the insulating layer 105, an EL layer 113B covering the top and sides of the pixel electrode 111B, a common layer 114 on the EL layer 113B, and a common electrode 115 on the common layer 114. In the light-emitting element 130B, the EL layer 113B and the common layer 114 can be collectively referred to as the EL layer.

[0096] Of the pixel electrodes and common electrodes of a light-emitting element, one functions as the anode and the other as the cathode. In the following, unless otherwise specified, it is assumed that the pixel electrodes function as the anode and the common electrodes function as the cathode.

[0097] Furthermore, in the example shown in Figure 2, a mask layer 118R is located on the EL layer 113R of the light-emitting element 130R, a mask layer 118G is located on the EL layer 113G of the light-emitting element 130G, and a mask layer 118B is located on the EL layer 113B of the light-emitting element 130B. Mask layer 118R is a portion of the mask layer that remained after being prepared in contact with the upper surface of the EL layer 113R during processing. Similarly, mask layer 118G is a portion of the mask layer that remained after being prepared during the formation of the EL layer 113G, and mask layer 118B is a portion of the mask layer that remained after being prepared during the formation of the EL layer 113B. Thus, the display device 100 may have a portion of the mask layer that remained after being prepared to protect the EL layer during its manufacture. Two or all of the mask layers 118R, 118G, and 118B may be made of the same material, or different materials may be used for each other. In the following, mask layer 118R, mask layer 118G, and mask layer 118B may be collectively referred to as mask layer 118.

[0098] In Figure 2, one end of the mask layer 118R is aligned with, or approximately aligned with, the end of the EL layer 113R, and the other end of the mask layer 118R is located on the EL layer 113R. Here, it is preferable that the other end of the mask layer 118R overlaps with the pixel electrode 111R. In this case, the other end of the mask layer 118R is more likely to be formed on the approximately flat surface of the EL layer 113R. The same applies to the mask layer 118G and the mask layer 118B. Furthermore, the mask layer 118 remains, for example, between the upper surface of the island-shaped EL layer 113 and the insulating layer 125.

[0099] Furthermore, if the edges are aligned or roughly aligned, and the top surface shapes match or roughly match, then in a plan view, at least a portion of the contours overlaps between the stacked layers. This includes, for example, cases where the upper and lower layers are processed with the same mask pattern, or partially with the same mask pattern. However, strictly speaking, the contours may not overlap, and the upper layer may be located inside the lower layer, or the upper layer may be located outside the lower layer; in this case as well, the edges are said to be roughly aligned, or the top surface shapes roughly match.

[0100] Each side of EL layer 113R, EL layer 113G, and EL layer 113B is covered by insulating layer 125. Insulating layer 127 overlaps with each side of EL layer 113R, EL layer 113G, and EL layer 113B via insulating layer 125.

[0101] Furthermore, portions of the upper surfaces of EL layer 113R, EL layer 113G, and EL layer 113B are covered by the mask layer 118. The insulating layer 125 and insulating layer 127 overlap portions of the upper surfaces of EL layer 113R, EL layer 113G, and EL layer 113B via the mask layer 118.

[0102] By covering a portion of the upper surface and sides of the EL layer 113R, EL layer 113G, and EL layer 113B with at least one of the insulating layer 125, insulating layer 127, and mask layer 118, contact between the common layer 114 or common electrode 115 and the sides of the EL layer 113R, EL layer 113G, and EL layer 113B is suppressed, thereby preventing a short circuit of the light-emitting element 130. This improves the reliability of the light-emitting element 130.

[0103] The insulating layer 125 is preferably in contact with the respective sides of the EL layers 113R, 113G, and 113B. This prevents peeling of the EL layers 113R, 113G, and 113B. The close contact between the insulating layer 125 and the EL layer 113 provides the effect of fixing or bonding the EL layer 113 to the insulating layer 125. This improves the reliability of the light-emitting element 130 and increases the manufacturing yield of the light-emitting element.

[0104] Furthermore, as shown in Figure 2, the insulating layers 125 and 127 cover both a portion of the upper surface and the sides of the EL layers 113R, 113G, and 113B, thereby more effectively preventing delamination of the EL layer 113 and improving the reliability of the light-emitting element 130. In addition, the manufacturing yield of the light-emitting element 130 can be more effectively improved.

[0105] Figure 2 shows an example where the stacked structure of the EL layer 113R, mask layer 118R, insulating layer 125, and insulating layer 127 is located on the edge of the pixel electrode 111R. Similarly, the stacked structure of the EL layer 113G, mask layer 118G, insulating layer 125, and insulating layer 127 is located on the edge of the pixel electrode 111G, and the stacked structure of the EL layer 113B, mask layer 118B, insulating layer 125, and insulating layer 127 is located on the edge of the pixel electrode 111B.

[0106] Figure 2 shows a configuration in which the end of the pixel electrode 111R is covered by the EL layer 113R, and the insulating layer 125 is in contact with the side surface of the EL layer 113R. Similarly, the end of the pixel electrode 111G is covered by the EL layer 113G, and the end of the pixel electrode 111B is covered by the EL layer 113B, and the insulating layer 125 is in contact with the side surfaces of the EL layer 113G and the EL layer 113B.

[0107] The insulating layer 127 is provided on the insulating layer 125 so as to fill the recesses formed in the insulating layer 125. The insulating layer 127 can be configured to overlap a portion of the upper surface and side surfaces of the EL layers 113R, EL layer 113G, and EL layer 113B, respectively, via the insulating layer 125. Preferably, the insulating layer 127 covers at least a portion of the side surfaces of the insulating layer 125.

[0108] By providing insulating layers 125 and 127, the gaps between adjacent island-like layers can be filled, thereby reducing extreme irregularities on the formed surfaces of layers (e.g., common layer 114 and common electrode 115, etc.) on the EL layer 113, and making them flatter. Consequently, the coverage of the common layer 114 and common electrode 115, etc., can be improved.

[0109] A recess 134 is provided on the upper surface of the insulating layer 127. For example, the insulating layer 127 may have a concave curved shape in the recess 134. The recess 134 has a region that overlaps with a region 133 between two adjacent light-emitting elements 130. Region 133 may be, for example, a region located between two adjacent EL layers 113. The insulating layer 127 may be provided in region 133. The insulating layer 127 can be said to have region 133.

[0110] The recess 134 is preferably provided in the center or near the center of the insulating layer 127 in a cross-sectional view. For example, the portion of the recess 134 with the minimum height in a cross-sectional view can be provided in a position that does not overlap with the EL layer 113. For example, the portion of the recess 134 with the minimum height can be provided in the center or near the center of the insulating layer 127 in a cross-sectional view. This allows for the distribution of stress on the insulating layer 127 over two adjacent EL layers 113. Therefore, it is possible to suppress the application of a larger stress to one of two adjacent EL layers 113 compared to the other. However, the present invention is not limited to this, and for example, the portion of the recess 134 with the minimum height in a cross-sectional view may overlap with the EL layer 113. Even in this case, it is preferable to have a configuration that allows for the distribution of stress on the insulating layer 127 over two adjacent EL layers 113, taking into consideration the difference in film thickness between the two adjacent EL layers 113.

[0111] The presence of the recess 134 in the insulating layer 127 allows for stress relief in the insulating layer 127 compared to, for example, a case where the insulating layer 127 does not have the recess 134 and the maximum height portion of the recess 134 in cross-sectional view is located in the center of the insulating layer 127. More specifically, by configuring the insulating layer 127 to have the recess 134, local compressive stress occurring at the edges of the insulating layer 127 can be relieved, thereby suppressing one or more of the following: delamination between the EL layer 113 and the mask layer 118, delamination between the mask layer 118 and the insulating layer 125, and delamination between the insulating layer 125 and the insulating layer 127. Therefore, the display device 100 can be a highly reliable display device. Furthermore, the display device 100 can be manufactured using a method with a high yield.

[0112] As mentioned above, an insulating layer 127 is provided on the insulating layer 125 to fill the recesses formed in the insulating layer 125. The insulating layer 127 is also provided between the island-shaped EL layers 113. In other words, the display device 100 is subjected to a process (hereinafter referred to as process 1) in which the island-shaped EL layers 113 are formed, and then the insulating layer 127 is provided so as to overlap with the edges of the island-shaped EL layers 113. On the other hand, a process different from process 1 is a process (hereinafter referred to as process 2) in which the pixel electrodes 111 are formed in an island shape, an insulating layer (also referred to as a dam or structure) is formed to cover the upper edges of the pixel electrodes 111, and then the pixel electrodes 111 and the island-shaped EL layers 113 are formed on the insulating layer.

[0113] Process 1 is preferable to Process 2 because it allows for a wider margin. More specifically, Process 1 provides a wider margin for alignment accuracy between different patterns and a display device with less variation in characteristics compared to Process 2. Therefore, since the manufacturing method for the display device 100 follows the process of Process 1, it is possible to provide a display device with less variation and high display quality.

[0114] EL layer 113R, EL layer 113G, and EL layer 113B each have at least an emissive layer. For example, EL layer 113R may have an emissive layer that emits red light, EL layer 113G may have an emissive layer that emits green light, and EL layer 113B may have an emissive layer that emits blue light. EL layer 113R, EL layer 113G, or EL layer 113B may emit light such as cyan, magenta, yellow, white, or infrared.

[0115] The EL layers 113R, 113G, and 113B are spaced apart from each other. By providing the EL layers 113 in an island-like arrangement for each light-emitting element 130, leakage current between adjacent light-emitting elements 130 can be suppressed. This prevents crosstalk caused by unintended light emission, enabling the realization of a display device with extremely high contrast. In particular, it enables the realization of a display device with high current efficiency at low brightness levels.

[0116] The island-shaped EL layer 113 can be formed by depositing an EL film and processing the EL film, for example, using photolithography. For example, EL layer 113R can be formed by depositing and processing an EL film that will become EL layer 113R, EL layer 113G can be formed by depositing and processing an EL film that will become EL layer 113G, and EL layer 113B can be formed by depositing and processing an EL film that will become EL layer 113B.

[0117] The EL layer 113 is provided so as to cover the top and sides of the pixel electrode 111. This makes it easier to increase the aperture ratio of the display device 100 compared to a configuration where the edges of the EL layer 113 are located inside the edges of the pixel electrode 111. In addition, by covering the sides of the pixel electrode 111 with the EL layer 113, contact between the pixel electrode 111 and the common electrode 115 can be suppressed, thereby suppressing short circuits of the light-emitting element 130. Furthermore, the distance between the light-emitting region of the EL layer 113 (i.e., the region overlapping with the pixel electrode 111) and the edges of the EL layer 113 can be increased. Since the edges of the EL layer 113 may be damaged during processing, using a region away from the edges of the EL layer 113 as the light-emitting region can sometimes improve the reliability of the light-emitting element 130.

[0118] The film thicknesses of the EL layer 113R, EL layer 113G, and EL layer 113B can be different. For example, it is preferable to set the film thickness to correspond to the optical path length that intensifies the light emitted by each of the EL layers 113R, EL layer 113G, and EL layer 113B. This makes it possible to realize a microcavity structure and improve the color purity of the light emitted from the sub-pixel 110.

[0119] It is preferable that the ends of the pixel electrodes 111R, 111G, and 111B each have a tapered shape. Specifically, it is preferable that the ends of the pixel electrodes 111R, 111G, and 111B each have a tapered shape with a taper angle of less than 90°. When the ends of these pixel electrodes have a tapered shape, the EL layers 113R, 113G, and 113B provided along the sides of the pixel electrodes have inclined surfaces. By making the sides of the pixel electrodes tapered, the coverage of the EL layers provided along the sides of the pixel electrodes can be improved.

[0120] In Figure 2, there is no insulating layer covering the upper edge of the pixel electrode 111R between the pixel electrode 111R and the EL layer 113R. Similarly, there is no insulating layer covering the upper edge of the pixel electrode 111G between the pixel electrode 111G and the EL layer 113G. Furthermore, there is no insulating layer covering the upper edge of the pixel electrode 111B between the pixel electrode 111B and the EL layer 113B. Therefore, the distance between adjacent light-emitting elements 130 can be made extremely narrow. Consequently, a high-definition or high-resolution display device can be produced. Additionally, a mask for forming the insulating layer becomes unnecessary, reducing the manufacturing cost of the display device.

[0121] Furthermore, by not providing an insulating layer covering the edges of the pixel electrode 111 between the pixel electrode 111 and the EL layer 113, in other words, by not providing an insulating layer between the pixel electrode 111 and the EL layer 113, the light emitted from the EL layer 113 can be efficiently extracted. Therefore, the display device 100 can have extremely low viewing angle dependence. By reducing viewing angle dependence, the visibility of images on the display device 100 can be improved. For example, in the display device 100, the viewing angle (the maximum angle at which a constant contrast ratio is maintained when viewing the screen from an oblique direction) can be set to a range of 100° or more and less than 180°, preferably 150° or more and 170° or less. Note that the above viewing angle can be applied to both the vertical and horizontal directions.

[0122] Insulating layer 101, insulating layer 103, and insulating layer 105 function as interlayer insulating layers. Various inorganic insulating films such as oxide insulating films, nitride insulating films, oxidative nitride insulating films, and nitride oxide insulating films can be suitably used as insulating layers 101, insulating layer 103, and insulating layer 105. Specifically, for example, silicon oxide film, silicon oxidative nitride film, aluminum oxide film, silicon nitride film, or silicon nitride oxide film can be used.

[0123] In this specification, "oxide nitride" refers to a material in which the oxygen content is greater than the nitrogen content, and "nitride oxide" refers to a material in which the nitrogen content is greater than the oxygen content. For example, when "silicon oxynitride" is written, it refers to a material in which the oxygen content is greater than the nitrogen content, and when "silicon nitride oxide" is written, it refers to a material in which the nitrogen content is greater than the oxygen content.

[0124] The insulating layer 104 functions as a barrier layer that prevents impurities such as water from entering the light-emitting element 130. As the insulating layer 104, a film that is less permeable to hydrogen or oxygen than a silicon oxide film can be used, such as a silicon nitride film, an aluminum oxide film, or a hafnium oxide film.

[0125] The thickness of the insulating layer 105 in areas that do not overlap with the pixel electrode 111 may be thinner than the thickness of the insulating layer 105 in areas that do overlap with the pixel electrode 111. In other words, the insulating layer 105 may have recesses in areas that do not overlap with the pixel electrode 111. These recesses may be formed, for example, as a result of the pixel electrode 111 formation process.

[0126] The conductive layer 102 functions as wiring. The conductive layer 102 is electrically connected to the light-emitting element 130 via the plug 106.

[0127] Various conductive materials can be used for the conductive layer 102 and the plug 106. For example, metals such as aluminum (Al), titanium (Ti), chromium (Cr), nickel (Ni), copper (Cu), yttrium (Y), zirconium (Zr), tin (Sn), zinc (Zn), silver (Ag), platinum (Pt), gold (Au), molybdenum (Mo), tantalum (Ta), or tungsten (W), or alloys mainly composed of these metals (such as an alloy of silver, palladium (Pd), and copper (Ag-Pd-Cu(APC))). In addition, oxides such as tin oxide or zinc oxide may be used for the conductive layer 102 and the plug 106.

[0128] The light-emitting element 130 may be a single structure (a structure having only one light-emitting unit) or a tandem structure (a structure having multiple light-emitting units). The light-emitting unit has at least one light-emitting layer.

[0129] As described above, EL layer 113R, EL layer 113G, and EL layer 113B each have at least an emissive layer. For example, EL layer 113R may have an emissive layer that emits red light, EL layer 113G may have an emissive layer that emits green light, and EL layer 113B may have an emissive layer that emits blue light.

[0130] Furthermore, when using a tandem light-emitting element, for example, the EL layer 113R can have a structure having multiple light-emitting units that emit red light, the EL layer 113G can have a structure having multiple light-emitting units that emit green light, and the EL layer 113B can have a structure having multiple light-emitting units that emit blue light. It is preferable to provide a charge generation layer between each light-emitting unit.

[0131] Furthermore, each of the EL layers 113R, 113G, and 113B may have one or more of the following: a hole injection layer, a hole transport layer, a hole blocking layer, a charge generation layer, an electron blocking layer, an electron transport layer, and an electron injection layer.

[0132] In this specification, among the layers of the EL layer, layers other than the light-emitting layer are referred to as functional layers. A functional layer may have one or more of the above-mentioned hole injection layer, hole transport layer, hole blocking layer, charge generation layer, electron blocking layer, electron transport layer, and electron injection layer.

[0133] For example, if the pixel electrode of the light-emitting element 130 functions as an anode and the common electrode 115 functions as a cathode, the EL layers 113R, EL layer 113G, and EL layer 113B may have a hole injection layer, a hole transport layer, an emissive layer, and an electron transport layer in this order. That is, the EL layer 113 can be configured such that, for example, a first functional layer having a hole injection layer and a hole transport layer, an emissive layer, and a second functional layer having an electron transport layer are stacked from bottom to top. An electron blocking layer may also be present between the hole transport layer and the emissive layer. A hole blocking layer may also be present between the electron transport layer and the emissive layer. An electron injection layer may also be present on the electron transport layer. The first functional layer may have either a hole injection layer or a hole transport layer, but not the other. The second functional layer may have an electron injection layer or it may not have an electron transport layer.

[0134] Furthermore, for example, if the pixel electrode of the light-emitting element 130 functions as a cathode and the common electrode 115 functions as an anode, the EL layers 113R, 113G, and 113B may have an electron injection layer, an electron transport layer, an emissive layer, and a hole transport layer in this order. That is, the EL layer 113 can be configured such that, for example, a first functional layer having an electron injection layer and an electron transport layer, an emissive layer, and a second functional layer having a hole transport layer are stacked from bottom to top. A hole blocking layer may also be present between the electron transport layer and the emissive layer. An electron blocking layer may also be present between the hole transport layer and the emissive layer. A hole injection layer may also be present on the hole transport layer. The first functional layer may have either an electron injection layer or an electron transport layer, but not the other. The second functional layer may have a hole injection layer or it may not have a hole transport layer.

[0135] Thus, it is preferable that EL layers 113R, EL layers 113G, and EL layers 113B have an emissive layer and a carrier transport layer (electron transport layer or hole transport layer) on the emissive layer. Furthermore, it is preferable that EL layers 113R, EL layers 113G, and EL layers 113B have an emissive layer and a carrier block layer (hole block layer or electron block layer) on the emissive layer. Furthermore, it is preferable that EL layers 113R, EL layers 113G, and EL layers 113B have an emissive layer, a carrier block layer on the emissive layer, and a carrier transport layer on the carrier block layer. Since the surfaces of EL layers 113R, EL layers 113G, and EL layers 113B are exposed during the manufacturing process of the display device, by providing one or both of the carrier transport layer and the carrier block layer on the emissive layer, it is possible to prevent the emissive layer from being exposed to the outermost surface and reduce the damage to the emissive layer. This can improve the reliability of the light-emitting element.

[0136] The heat resistance temperature of the compounds contained in EL layer 113R, EL layer 113G, and EL layer 113B is preferably 100°C to 180°C, preferably 120°C to 180°C, and more preferably 140°C to 180°C. For example, the glass transition temperature (Tg) of these compounds is preferably 100°C to 180°C, preferably 120°C to 180°C, and more preferably 140°C to 180°C.

[0137] In particular, it is preferable that the heat resistance temperature of the functional layer provided on the light-emitting layer is high. Furthermore, it is even more preferable that the heat resistance temperature of the functional layer provided in contact with the light-emitting layer is high. The high heat resistance of the functional layer makes it possible to effectively protect the light-emitting layer and reduce the damage it receives.

[0138] The functional layer provided on the light-emitting layer is preferably an organic compound having a heteroaromatic ring skeleton containing one selected from a pyridine ring, a diazine ring, and a triazine ring, and a bicarbazole skeleton, or an organic compound having a condensed heteroaromatic ring skeleton containing a pyridine ring or a diazine ring, and a bicarbazole skeleton, and preferably having a Tg of 100°C to 180°C, preferably 120°C to 180°C, and more preferably 140°C to 180°C. A functional layer using such an organic compound can have one or both functions as a hole-blocking layer and an electron-transporting layer. It should be noted that the functional layer using such an organic compound is not limited to being located above the light-emitting layer (upper electrode side), but may also be provided below the light-emitting layer (lower electrode side).

[0139] Specific examples of such organic compounds include 2-{3-[3-(9-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}dibenzo[f,h]quinoxaline (abbreviation: 2mPCCzPDBq), 2-{3-[2-(9-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}dibenzo[f,h]quinoxaline (abbreviation: 2mPCCzPDBq-02), 9-[3-(4,6-diphenyl-1,3, 5-triazin-2-yl)phenyl]-9'-phenyl-3,3'-bi-9H-carbazole (abbreviation: mPCCzPTzn), 9-[3-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-9'-phenyl-2,3'-bi-9H-carbazole (abbreviation: mPCCzPTzn-02), 9-[4-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-9'-phenyl-3,3'-bi-9H-carbazole (abbreviation: PC CzPTzn), 9-(4,6-diphenyl-1,3,5-triazine-2-yl)-9'-phenyl-3,3'-bi-9H-carbazole (abbreviation: PCCzTzn), 9-[3-(4,6-diphenyl-pyrimidine-2-yl)phenyl]-9'-phenyl-3,3'-bi-9H-carbazole (abbreviation: 2PCCzPPm), 9-(4,6-diphenyl-pyrimidine-2-yl)-9'-phenyl-2,3'-bi-9H-carbazole (abbreviation: 2PCCzPm) Examples include 9-(4,6-diphenylpyrimidine-2-yl)-9'-phenyl-3,3'-bi-9H-carbazole (abbreviation: 2PCCzPm-02), 4-(9'-phenyl[2,3'-bi-9H-carbazole]-9-yl)benzofl[3,2-d]pyrimidine (abbreviation: 4PCCzBfpm-02), and 4-{3-[3-(9-phenyl-9H-carbazole-3-yl)-9H-carbazole-9-yl]phenyl}benzo[h]quinazoline.

[0140] Furthermore, it is preferable that the heat resistance temperature of the light-emitting layer be high. This helps to prevent damage to the light-emitting layer due to heating, which can reduce luminous efficiency and shorten its lifespan.

[0141] Furthermore, the EL layer 113R, EL layer 113G, and EL layer 113B can be configured to include, for example, a first light-emitting unit, a charge generation layer, and a second light-emitting unit.

[0142] The second light-emitting unit preferably comprises a light-emitting layer and a carrier transport layer (electron transport layer or hole transport layer) on the light-emitting layer. Furthermore, the second light-emitting unit preferably comprises a light-emitting layer and a carrier block layer (hole block layer or electron block layer) on the light-emitting layer. Furthermore, the second light-emitting unit preferably comprises a light-emitting layer, a carrier block layer on the light-emitting layer, and a carrier transport layer on the carrier block layer. Since the surface of the second light-emitting unit is exposed during the manufacturing process of the display device, providing one or both of the carrier transport layer and the carrier block layer on the light-emitting layer suppresses exposure of the light-emitting layer to the outermost surface, thereby reducing damage to the light-emitting layer. This improves the reliability of the light-emitting element. If there are three or more light-emitting units, it is preferable that the uppermost light-emitting unit comprises a light-emitting layer and one or both of the carrier transport layer and the carrier block layer on the light-emitting layer.

[0143] When the pixel electrode 111 functions as the anode and the common electrode 115 functions as the cathode, for example, the common layer 114 has at least one of an electron injection layer or an electron transport layer, for example, an electron injection layer. Alternatively, the common layer 114 may have an electron transport layer and an electron injection layer stacked together. On the other hand, when the pixel electrode 111 functions as the cathode and the common electrode 115 functions as the anode, for example, the common layer 114 has at least one of a hole injection layer or a hole transport layer, for example, a hole injection layer. Alternatively, the common layer 114 may have a hole transport layer and a hole injection layer stacked together. The common layer 114 is shared by the light-emitting element 130R, the light-emitting element 130G, and the light-emitting element 130B.

[0144] Furthermore, the common electrode 115 is shared by the light-emitting element 130R, light-emitting element 130G, and light-emitting element 130B, similar to the common layer 114.

[0145] The common layer 114 and common electrode 115 are provided on the EL layer 113R, EL layer 113G, EL layer 113B, mask layer 118, insulating layer 125, and insulating layer 127. Before the insulating layer 125 and insulating layer 127 are provided, a step difference occurs due to the region where the pixel electrode 111 and EL layer 113 are provided and the region where the pixel electrode 111 and EL layer 113 are not provided (the region between the light-emitting elements 130). The display device 100 can flatten this step difference by having the insulating layer 125 and insulating layer 127, and can improve the coverage of the common layer 114 and common electrode 115. Therefore, connection failures due to step breaks can be suppressed. In addition, it is possible to suppress the local thinning of the common electrode 115 due to the step difference and the increase in electrical resistance.

[0146] Next, we will describe examples of materials for the insulating layer 125 and the insulating layer 127.

[0147] The insulating layer 125 can be an insulating layer having an inorganic material. For example, inorganic insulating films such as oxide insulating films, nitride insulating films, oxidative nitride insulating films, and nitride oxide insulating films can be used for the insulating layer 125. The insulating layer 125 may be a single layer or a laminated structure. Examples of oxide insulating films include silicon oxide film, aluminum oxide film, magnesium oxide film, indium gallium zinc oxide film, gallium oxide film, germanium oxide film, yttrium oxide film, zirconium oxide film, lanthanum oxide film, neodymium oxide film, hafnium oxide film, and tantalum oxide film. Examples of nitride insulating films include silicon nitride film and aluminum nitride film. Examples of oxidative nitride insulating films include silicon oxidative nitride film and aluminum oxidative nitride film. Examples of nitride oxide insulating films include silicon nitride film and aluminum nitride film. In particular, aluminum oxide is preferred because it has a high selectivity ratio with the EL layer during etching and has the function of protecting the EL layer during the formation of the insulating layer 127, which will be described later. In particular, by applying an inorganic insulating film such as an aluminum oxide film, a hafnium oxide film, or a silicon oxide film formed by atomic layer deposition (ALD) to the insulating layer 125, an insulating layer 125 with fewer pinholes and excellent protection for the EL layer can be formed. Alternatively, the insulating layer 125 may have a laminated structure of a film formed by ALD and a film formed by sputtering. For example, the insulating layer 125 may have a laminated structure of an aluminum oxide film formed by ALD and a silicon nitride film formed by sputtering.

[0148] Preferably, the insulating layer 125 functions as a barrier insulating layer against at least one of water and oxygen. Furthermore, preferably, the insulating layer 125 has the function of suppressing the diffusion of at least one of water and oxygen. Also, preferably, the insulating layer 125 has the function of capturing or fixing (also known as gettering) at least one of water and oxygen.

[0149] In this specification, the term "barrier insulating layer" refers to an insulating layer that has barrier properties. Furthermore, in this specification, "barrier properties" refers to a function that suppresses the diffusion of the corresponding substance (also known as low permeability), or a function that captures or fixes the corresponding substance (also known as gettering).

[0150] The insulating layer 125 has the function of a barrier insulating layer or a gettering function, thereby suppressing the intrusion of impurities (typically at least one of water and oxygen) that could diffuse from the outside into the light-emitting element 130. This configuration makes it possible to provide a highly reliable light-emitting element and, furthermore, a highly reliable display device.

[0151] Furthermore, it is preferable that the insulating layer 125 has a low impurity concentration. This prevents impurities from mixing from the insulating layer 125 into the EL layer 113 and degrading the EL layer 113. In addition, by lowering the impurity concentration in the insulating layer 125, the barrier properties against at least one of water and oxygen can be improved. For example, it is desirable that the insulating layer 125 has a sufficiently low hydrogen concentration and a sufficiently low carbon concentration, preferably both.

[0152] Furthermore, the same material can be used for the insulating layer 125 and the mask layers 118R, 118G, and 118B. In this case, the boundary between any of the mask layers 118R, 118G, and 118B and the insulating layer 125 may become unclear and indistinguishable. Therefore, the insulating layer 125 may be identified as a single layer with any of the mask layers 118R, 118G, and 118B. In other words, it may be observed that a single layer is provided in contact with a portion of the upper surface and side surface of each of the EL layers 113R, 113G, and 113B, and that the insulating layer 127 covers at least a portion of the side surface of that single layer.

[0153] The insulating layer 127, provided on the insulating layer 125, has the function of flattening the extreme irregularities in the insulating layer 125 formed between adjacent light-emitting elements 130. In other words, the presence of the insulating layer 127 has the effect of improving the flatness of the surface forming the common electrode 115.

[0154] As the insulating layer 127, an insulating layer having an organic material can be suitably used. As the organic material, a photosensitive material, such as a photosensitive organic resin, is preferred, and for example, a photosensitive resin composition containing an acrylic resin is preferred. In this specification, the term "acrylic resin" does not refer only to polymethacrylate esters or methacrylic resins, but may refer to acrylic polymers in a broad sense.

[0155] Furthermore, as the insulating layer 127, acrylic resin, polyimide resin, epoxy resin, imide resin, polyamide resin, polyimidoamide resin, silicone resin, siloxane resin, benzocyclobutene resin, phenol resin, and precursors of these resins may be used. Alternatively, as the insulating layer 127, organic materials such as polyvinyl alcohol (PVA), polyvinyl butyral, polyvinylpyrrolidone, polyethylene glycol, polyglycerin, pullulan, water-soluble cellulose, or alcohol-soluble polyamide resin may be used. Additionally, a photoresist may be used as the photosensitive resin. A positive-type material can be used as the photosensitive organic resin.

[0156] The insulating layer 127 may be made of a material that absorbs visible light. By absorbing the light emitted from the light-emitting element 130, the insulating layer 127 can suppress light leakage (stray light) from the light-emitting element 130 to adjacent light-emitting elements 130 through the insulating layer 127. This improves the display quality of the display device. Furthermore, since the display quality can be improved without using a polarizing plate in the display device, the display device can be made lighter and thinner.

[0157] Examples of materials that absorb visible light include materials containing pigments such as black, materials containing dyes, light-absorbing resin materials (e.g., polyimide), and resin materials that can be used in color filters (color filter materials). In particular, it is preferable to use a resin material which is made by laminating or mixing two or more color filter materials, as this can enhance the visible light shielding effect. In particular, by mixing three or more color filter materials, it is possible to create a black or near-black resin layer.

[0158] Furthermore, it is preferable that the material used for the insulating layer 127 has a low volume shrinkage rate. This makes it easier to form the insulating layer 127 in the desired shape. It is also preferable that the insulating layer 127 has a low volume shrinkage rate after curing. This makes it easier to maintain the shape of the insulating layer 127 in various processes after its formation. Specifically, the volume shrinkage rate of the insulating layer 127 after heat curing is preferably 10% or less, more preferably 5% or less, and even more preferably 1% or less. Here, as the volume shrinkage rate, one of the volume shrinkage rate due to light irradiation and the volume shrinkage rate due to heating, or the sum of both, can be used.

[0159] By providing a protective layer 131 on the light-emitting element 130, the reliability of the light-emitting element 130 can be improved. The protective layer 131 may be a single layer or a laminated structure of two or more layers.

[0160] The conductivity of the protective layer 131 is not required. At least one of an insulating film, a semiconductor film, and a conductive film can be used as the protective layer 131.

[0161] For example, inorganic insulating films such as oxide insulating films, nitride insulating films, oxidoxide-nitriding insulating films, and nitride-oxide insulating films can be used for the protective layer 131. Specific examples of these inorganic insulating films are given in the description of the insulating layer 125. In particular, the protective layer 131 preferably has a nitride insulating film or a nitride-oxide insulating film, and more preferably a nitride insulating film.

[0162] Furthermore, the protective layer 131 may also be an inorganic film containing In-Sn oxide (also known as ITO), In-Zn oxide, Ga-Zn oxide, Al-Zn oxide, or indium gallium zinc oxide (In-Ga-Zn oxide, also known as IGZO). The inorganic film is preferably highly resistive, and more specifically, it is preferably more resistive than the common electrode 115. The inorganic film may further contain nitrogen.

[0163] The presence of an inorganic film in the protective layer 131 prevents oxidation of the common electrode 115 and suppresses the intrusion of impurities (such as moisture and oxygen) into the light-emitting element, thereby suppressing degradation of the light-emitting element and improving the reliability of the display device.

[0164] When the light emitted from the light-emitting element 130 is extracted via a protective layer 131, it is preferable that the protective layer 131 has high transmittance to visible light. For example, ITO, IGZO, and aluminum oxide are preferred because they are inorganic materials with high transmittance to visible light.

[0165] As the protective layer 131, 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 can be used. By using such a laminated structure, impurities (water, oxygen, etc.) that enter the EL layer 113 can be suppressed.

[0166] Furthermore, the protective layer 131 may have an organic film. For example, the protective layer 131 may have both an organic film and an inorganic film. Examples of organic materials that can be used for the protective layer 131 include organic insulating materials that can be used for the insulating layer 127.

[0167] The protective layer 131 may have a two-layer structure formed using different film deposition methods. Specifically, the first layer of the protective layer 131 may be formed using the ALD method, and the second layer of the protective layer 131 may be formed using the sputtering method.

[0168] A light-shielding layer may be provided on the surface of the substrate 120 facing the resin layer 122. Various optical components can also be placed on the outside of the substrate 120. Examples of optical components include polarizing plates, phase difference plates, light diffusion layers (e.g., diffusion films), anti-reflective layers, and light-gathering films. Furthermore, surface protection layers such as an antistatic film to suppress dust adhesion, a water-repellent film to prevent dirt from adhering, a hard coat film to suppress scratches during use, or an impact-absorbing layer may be placed on the outside of the substrate 120. For example, a glass layer or a silica layer (SiO₂) may be used as the surface protection layer. x By providing a protective layer, surface contamination and scratching can be suppressed, which is preferable. Furthermore, as a surface protective layer, DLC (diamond-like carbon), aluminum oxide (AlO2) x ), polyester-based materials, or polycarbonate-based materials may be used. It is preferable to use a material with high transmittance to visible light for the surface protective layer. Furthermore, it is preferable to use a material with high hardness for the surface protective layer.

[0169] The substrate 120 can be made of glass, quartz, ceramic, sapphire, resin, metal, alloy, or semiconductor. The substrate on the side that extracts light from the light-emitting element should be made of a material that transmits the light. Using a flexible material for the substrate 120 can increase the flexibility of the display device. Alternatively, a polarizing plate may be used as the substrate 120.

[0170] As the substrate 120, polyester resins such as polyethylene terephthalate (PET) or polyethylene naphthalate (PEN), polyacrylonitrile resin, acrylic resin, polyimide resin, polymethyl methacrylate resin, polycarbonate (PC) resin, polyethersulfone (PES) resin, polyamide resin (nylon or aramid, etc.), polysiloxane resin, cycloolefin resin, polystyrene resin, polyamide-imide resin, polyurethane resin, polyvinyl chloride resin, polyvinylidene chloride resin, polypropylene resin, polytetrafluoroethylene (PTFE) resin, ABS resin, or cellulose nanofiber can be used. Glass with a thickness sufficient to provide flexibility may also be used for the substrate 120.

[0171] Furthermore, when a circular polarizing plate is superimposed on a display device, it is preferable to use a substrate with high optical isotropy for the substrate of the display device. A substrate with high optical isotropy can also be said to have low birefringence (low amount of birefringence).

[0172] For substrates with high optical isotropy, the absolute value of the retardation (phase difference) is preferably 30 nm or less, more preferably 20 nm or less, and even more preferably 10 nm or less.

[0173] Examples of films with high optical isotropy include triacetylcellulose (TAC, also known as cellulose triacetate) film, cycloolefin polymer (COP) film, cycloolefin copolymer (COC) film, and acrylic film.

[0174] Furthermore, when a film is used as the substrate, the film may absorb water, potentially causing wrinkles or other shape changes in the display device. For this reason, it is preferable to use a film with a low water absorption rate as the substrate. For example, it is preferable to use a film with a water absorption rate of 1% or less, more preferable to use a film with a water absorption rate of 0.1% or less, and even more preferable to use a film with a water absorption rate of 0.01% or less.

[0175] As the resin layer 122, various curing adhesives can be used, such as UV-curing adhesives, reaction-curing adhesives, thermosetting adhesives, or anaerobic adhesives. Examples of these adhesives include epoxy resins, acrylic resins, silicone resins, phenolic resins, polyimide resins, imide resins, PVC (polyvinyl chloride) resins, PVB (polyvinyl butyral) resins, and EVA (ethylene vinyl acetate) resins. Materials with low moisture permeability, such as epoxy resins, are particularly preferred. Two-component mixed resins may also be used. Alternatively, for example, an adhesive sheet may be used.

[0176] Next, the structure of the insulating layer 127 and its vicinity will be described using Figures 3A and 3B. Figure 3A is an enlarged cross-sectional view of the insulating layer 127 and its surrounding area between EL layer 113R and EL layer 113G. In the following explanation, the insulating layer 127 between EL layer 113R and EL layer 113G will be used as an example, but the same applies to the insulating layer 127 between EL layer 113G and EL layer 113B, and the insulating layer 127 between EL layer 113B and EL layer 113R, etc. Figure 3B is an enlarged view of the end of the insulating layer 127 on EL layer 113G and its vicinity, as shown in Figure 3A. In the following explanation, the end of the insulating layer 127 on EL layer 113G will be used as an example, but the same applies to the end of the insulating layer 127 on EL layer 113R, and the end of the insulating layer 127 on EL layer 113B, etc.

[0177] As shown in Figure 3A, an EL layer 113R is provided covering the pixel electrode 111R, and an EL layer 113G is provided covering the pixel electrode 111G. A mask layer 118R is provided in contact with a part of the upper surface of the EL layer 113R, and a mask layer 118G is provided in contact with a part of the upper surface of the EL layer 113G.

[0178] An insulating layer 125 is provided in contact with the upper and side surfaces of the mask layer 118R, the upper and side surfaces of the mask layer 118G, the side surfaces of the EL layer 113R, the side surfaces of the EL layer 113G, and the upper surface of the insulating layer 105. An insulating layer 127 is provided in contact with the upper surface of the insulating layer 125. The insulating layer 127 overlaps with a portion of the upper surface and side surfaces of the EL layer 113R and a portion of the upper surface and side surfaces of the EL layer 113G via the insulating layer 125, and is in contact with at least a portion of the side surfaces of the insulating layer 125. The insulating layer 127 has a recess 134. The recess 134 has a region that overlaps with a region 133, for example, between two adjacent EL layers 113 (between EL layer 113R and EL layer 113G in Figure 3A).

[0179] As described above, the display device 100, by having insulating layers 125 and 127, can flatten the step between EL layer 113R and EL layer 113G, and improve the coverage of the common layer 114 and common electrode 115. Therefore, connection failures due to step breaks can be suppressed, and the local thinning of the common electrode 115 due to the step can be suppressed, which can increase electrical resistance. In addition, the insulating layer 127 has a recess 134, which can alleviate local stress generated at the edge of the insulating layer 127, and can suppress one or more of the following: delamination between EL layer 113 and mask layer 118, delamination between mask layer 118 and insulating layer 125, and delamination between insulating layer 125 and insulating layer 127. As a result, the display device 100 can be a highly reliable display device. Furthermore, the display device 100 can be manufactured using a method with a high yield.

[0180] A common layer 114 is provided covering the EL layer 113R, mask layer 118R, EL layer 113G, mask layer 118G, insulating layer 125, and insulating layer 127, and a common electrode 115 is provided on the common layer 114.

[0181] As shown in Figure 3A, the thickness of the insulating layer 105 in the region that does not overlap with the EL layer 113 may be thinner than the thickness of the insulating layer 105 in the region that overlaps with the EL layer 113. In other words, the insulating layer 105 may have recesses in the region that does not overlap with the EL layer 113. These recesses are formed, for example, as a result of the EL layer 113 formation process.

[0182] As shown in Figure 3B, the insulating layer 127 preferably has a tapered shape with a taper angle θ1 at its end in a cross-sectional view of the display device 100. The taper angle θ1 is the angle between the side surface of the insulating layer 127 and the substrate surface. However, the taper angle θ1 is not limited to this angle; it may also be the angle between the upper surface of the flat portion of the EL layer 113G or the upper surface of the flat portion of the pixel electrode 111G and the side surface of the insulating layer 127.

[0183] The taper angle θ1 of the insulating layer 127 is less than 90°, preferably 60° or less, more preferably 45° or less, and even more preferably 20° or less. By making the edges of the insulating layer 127 have such a forward taper shape, the common layer 114 and common electrode 115 provided on the insulating layer 127 can be formed with good coverage, and the occurrence of step breaks or localized thinning can be suppressed. As a result, the in-plane uniformity of the common layer 114 and common electrode 115 can be improved, and the display quality of the display device can be improved.

[0184] As shown in Figure 3B, it is preferable that the edge of the insulating layer 127 is located outside the edge of the insulating layer 125. This reduces the surface irregularities forming the common layer 114 and the common electrode 115, thereby improving the coverage of the common layer 114 and the common electrode 115.

[0185] As shown in Figure 3B, the insulating layer 125 preferably has a tapered shape with a taper angle θ2 at its end in a cross-sectional view of the display device 100. The taper angle θ2 is the angle between the side surface of the insulating layer 125 and the substrate surface. However, the taper angle θ2 is not limited to this angle; it may also be the angle between the upper surface of the flat portion of the EL layer 113G or the upper surface of the flat portion of the pixel electrode 111G and the side surface of the insulating layer 125.

[0186] The taper angle θ2 of the insulating layer 125 is less than 90°, preferably 60° or less, more preferably 45° or less, and even more preferably 20° or less.

[0187] The mask layer 118G preferably has a tapered shape with a taper angle θ3 at its end in a cross-sectional view of the display device 100, as shown in Figure 3B. The taper angle θ3 is the angle between the side surface of the mask layer 118G and the substrate surface. However, the taper angle θ3 is not limited to this angle; it may also be the angle between the upper surface of the flat portion of the EL layer 113G, or the upper surface of the flat portion of the pixel electrode 111G, and the side surface of the mask layer 118G.

[0188] The taper angle θ3 of the mask layer 118G is less than 90°, preferably 60° or less, more preferably 45° or less, and even more preferably 20° or less. By giving the mask layer 118G such a forward taper shape, the common layer 114 and the common electrode 115 provided on the mask layer 118G can be formed with good coverage.

[0189] It is preferable that the edges of the mask layer 118R and the mask layer 118G are located outside the edges of the insulating layer 125. This reduces the surface irregularities forming the common layer 114 and the common electrode 115, thereby improving the coverage of the common layer 114 and the common electrode 115.

[0190] As will be explained in detail later, if the etching process of the insulating layer 125 and the mask layer 118 is performed at the same time, side etching may cause the insulating layer 125 and the mask layer beneath the edge of the insulating layer 127 to disappear, forming a cavity. This cavity can cause unevenness on the surface forming the common layer 114 and the common electrode 115, making it easier for the common layer 114 and the common electrode 115 to break down. Therefore, by performing the etching process in two stages and performing a heat treatment between the two etching stages, even if a cavity is formed in the first etching stage, the heat treatment will deform the insulating layer 127 and fill the cavity. In addition, since the second etching stage involves etching a thin film, the amount of side etching is reduced, making it less likely for a cavity to form, or if a cavity does form, it can be made extremely small. Therefore, it is possible to suppress the formation of unevenness on the surface forming the common layer 114 and the common electrode 115, and to suppress the breaking down of the common layer 114 and the common electrode 115. Because the etching process is performed twice, the taper angles θ2 and θ3 may be different angles. Alternatively, taper angles θ2 and θ3 may be the same angle. Furthermore, taper angles θ2 and θ3 may each be smaller than taper angle θ1.

[0191] The insulating layer 127 may cover at least a portion of the side surface of the mask layer 118R and at least a portion of the side surface of the mask layer 118G. For example, Figure 3B shows an example where the insulating layer 127 in contact with and covers the inclined surface located at the edge of the mask layer 118G formed by the first etching process, while the inclined surface located at the edge of the mask layer 118G formed by the second etching process is exposed. These two inclined surfaces can sometimes be distinguished by their different taper angles. Alternatively, there may be little difference in the taper angles of the side surfaces formed by the two etching processes, making them indistinguishable.

[0192] Furthermore, Figures 4A and 4B show modified configurations of those shown in Figures 3A and 3B, illustrating an example where the insulating layer 127 covers the entire side surface of the mask layer 118R and the entire side surface of the mask layer 118G. Specifically, in Figure 4B, the insulating layer 127 covers both of the two inclined surfaces in contact with each other. This is preferable because it further reduces the unevenness of the surfaces forming the common layer 114 and the common electrode 115. Figure 4B shows an example where the edge of the insulating layer 127 is located outside the edge of the mask layer 118G. As shown in Figure 4B, the edge of the insulating layer 127 may be located outside the edge of the mask layer 118G, or it may be aligned with or approximately aligned with the edge of the mask layer 118G. Also, as shown in Figure 4B, the insulating layer 127 may be in contact with the EL layer 113G.

[0193] Furthermore, Figures 5A and 6A are modified versions of the configuration shown in Figure 3A, and Figures 5B and 6B are modified versions of the configuration shown in Figure 3B. Figures 5A, 5B, 6A, and 6B show examples in which the insulating layer 127 has a concave curved shape (also called a constricted portion, recess, indentation, etc.) on its side surface. Depending on the material of the insulating layer 127 and the formation conditions (heating temperature, heating time, heating atmosphere, etc.), a concave curved shape may be formed on the side surface of the insulating layer 127.

[0194] Figures 5A and 5B show examples where the insulating layer 127 covers a portion of the side surface of the mask layer 118G, leaving the rest of the side surface of the mask layer 118G exposed. Figures 6A and 6B show examples where the insulating layer 127 is in contact with and covers the entire side surface of the mask layer 118R and the entire side surface of the mask layer 118G.

[0195] In the configurations shown in Figures 4B, 5B, and 6B, it is preferable that the taper angles θ1 to θ3 are within the above ranges.

[0196] Furthermore, as shown in Figures 3A, 4A, 5A, and 6A, it is preferable that one end of the insulating layer 127 overlaps with the upper surface of the pixel electrode 111R, and the other end of the insulating layer 127 overlaps with the upper surface of the pixel electrode 111G. With this structure, the end of the insulating layer 127 can be formed on the generally flat region of the EL layer 113R and EL layer 113G. Therefore, it becomes relatively easy to form the tapered shape of the insulating layer 127, insulating layer 125, and mask layer 118. In addition, peeling of the film of the pixel electrode 111R, pixel electrode 111G, EL layer 113R, and EL layer 113G can be suppressed. On the other hand, the smaller the overlap portion between the upper surface of the pixel electrode 111 and the insulating layer 127, the wider the light-emitting region of the light-emitting element 130 becomes, and the aperture ratio can be increased, which is preferable.

[0197] As described above, in each configuration shown in Figures 3A to 6B, by providing insulating layer 127, insulating layer 125, mask layer 118R, and mask layer 118G, the common layer 114 and common electrode 115 can be formed with high coverage from the generally flat region of EL layer 113R to the generally flat region of EL layer 113G. This prevents the formation of divided areas in the common layer 114 and common electrode 115, as well as areas with locally thin film thickness. Therefore, connection failures caused by divided areas and increases in electrical resistance caused by locally thin film thickness can be suppressed between the light-emitting elements 130 in the common layer 114 and common electrode 115. As a result, the display device 100 can be a display device with high display quality.

[0198] Figure 7A is a cross-sectional view showing an example of the configuration of region 141 and the connection portion 140. In region 141, a conductive layer 109 is provided on the insulating layer 101, and an insulating layer 103 is provided on the insulating layer 101 and on the conductive layer 109. The conductive layer 109 can be formed in the same process as the conductive layer 102 shown in Figure 2, and may contain the same material as the conductive layer 102.

[0199] Region 141 is provided with an EL layer 113R on the insulating layer 105, a mask layer 118R on the insulating layer 105 and on the EL layer 113R, an insulating layer 125 on the mask layer 118R, an insulating layer 127 on the insulating layer 125, a common layer 114 on the insulating layer 127, a common electrode 115 on the common layer 114, a protective layer 131 on the common electrode 115, a resin layer 122 on the protective layer 131, and a substrate 120 on the resin layer 122. In region 141, the mask layer 118R is provided, for example, to cover the edge of the EL layer 113R. Depending on the manufacturing process of the display device 100, for example, an EL layer 113G or an EL layer 113B may be provided in region 141 instead of the EL layer 113R. Also, a mask layer 118G or a mask layer 118B may be provided in region 141 instead of the mask layer 118R.

[0200] The EL layer 113R provided in region 141 is not electrically connected to the common electrode 115. Therefore, the EL layer 113R provided in region 141 can be configured so that no voltage is applied to it, and thus the EL layer 113R provided in region 141 can be configured so that it does not emit light.

[0201] In a display device configured such that an EL layer 113R and a mask layer 118R are provided in region 141, as will be described in detail later, it is possible to prevent the conductive layer 109 from being exposed by etching or other means during the manufacturing process of the display device, which may result in the insulating layer 105, insulating layer 104, and a portion of the insulating layer 103 being removed. This prevents the conductive layer 109 from unintentionally coming into contact with other electrodes or layers. For example, it is possible to prevent a short circuit between the conductive layer 109 and the common electrode 115. As a result, the display device 100 can be made into a highly reliable display device. Furthermore, the display device 100 can be manufactured using a method with a high yield.

[0202] The connection portion 140 includes a conductive layer 123 on an insulating layer 105, a common layer 114 on the conductive layer 123, a common electrode 115 on the common layer 114, a protective layer 131 on the common electrode 115, a resin layer 122 on the protective layer 131, and a substrate 120 on the resin layer 122. A mask layer 118R is provided to cover the edge of the conductive layer 123, and the insulating layer 125, insulating layer 127, common layer 114, common electrode 115, and protective layer 131 are laminated on the mask layer 118R in this order. If a mask layer 118G or mask layer 118B is provided in region 141 instead of mask layer 118R, then a mask layer 118G or mask layer 118B is also provided in the connection portion 140 instead of mask layer 118R.

[0203] At the connection point 140, the conductive layer 123 and the common electrode 115 are electrically connected. The conductive layer 123 is electrically connected to, for example, an FPC (not shown). As a result, by supplying a power potential to the FPC, for example, the power potential can be supplied to the common electrode 115 via the conductive layer 123. The conductive layer 123 can be made of the same material as the pixel electrode 111 shown in Figure 2.

[0204] Here, if the electrical resistance of the common layer 114 in the thickness direction is negligibly small, then even if the common layer 114 is provided between the conductive layer 123 and the common electrode 115, conductivity between the conductive layer 123 and the common electrode 115 can be ensured. By providing the common layer 114 not only in the pixel portion 107 but also in the region 141 and the connection portion 140, the common layer 114 can be formed without using a metal mask, including, for example, a mask for defining the film deposition area (also called an area mask or rough metal mask, to distinguish it from a fine metal mask). Therefore, the manufacturing process of the display device 100 can be simplified.

[0205] In Figure 7A, the insulating layer 127 provided in region 141 and the insulating layer 127 provided in connection portion 140 do not have recesses 134, but these insulating layers 127 may have recesses 134.

[0206] Figure 7B shows a modified configuration of the one shown in Figure 7A, illustrating an example where the common layer 114 is not provided at the connection portion 140. In the example shown in Figure 7B, the conductive layer 123 and the common electrode 115 can be in contact. This reduces the electrical resistance between the conductive layer 123 and the common electrode 115. In Figure 7B, the common layer 114 is provided in the region 141 that overlaps with the EL layer 113R, and is not provided in the region that does not overlap with the EL layer 113R, but the configuration is not limited to this. For example, in region 141, the common layer 114 may not be provided in the region that overlaps with the EL layer 113R, or it may be provided in the region that does not overlap with the EL layer 113R.

[0207] [Configuration Example 2] Figure 8A shows a modified version of the configuration shown in Figure 2, in which sub-pixel 110R has a colored layer 132R, sub-pixel 110G has a colored layer 132G, and sub-pixel 110B has a colored layer 132B.

[0208] As shown in Figure 8A, the colored layers 132R, 132G, and 132B can be provided on the protective layer 131. In this case, it is preferable that the protective layer 131 is planar, but it does not have to be planar.

[0209] In the example shown in Figure 8A, the light-emitting element 130 of sub-pixel 110R, the light-emitting element 130 of sub-pixel 110G, and the light-emitting element 130 of sub-pixel 110B can all emit light of the same color, for example, white light. Even in this case, the display device 100 having the configuration shown in Figure 8A can display in full color by, for example, the colored layer 132R transmitting red light, the colored layer 132G transmitting green light, and the colored layer 132B transmitting blue light. Note that the colored layer 132R, the colored layer 132G, or the colored layer 132B may transmit light such as cyan, magenta, yellow, white, or infrared. Also, the light-emitting element 130 may emit infrared light, for example.

[0210] The display device 100 having the pixel section 107 with the configuration shown in Figure 8A does not require the EL layer 113 to be manufactured separately for each color, thus simplifying the manufacturing process of the display device 100. Therefore, the manufacturing cost of the display device 100 can be reduced, making the display device 100 a low-cost display device.

[0211] Adjacent colored layers 132 have overlapping regions on the insulating layer 127. For example, in the cross-section shown in Figure 8A, one end of colored layer 132G overlaps with colored layer 132R, and the other end of colored layer 132G overlaps with colored layer 132B. This suppresses light leakage from the light-emitting element 130 to adjacent sub-pixels 110. Therefore, for example, light emitted from a light-emitting element 130 provided in a sub-pixel 110G can be prevented from incident on colored layer 132R and colored layer 132B. Consequently, the display device 100 can be made into a display device with high display quality.

[0212] Figure 8B is a magnified cross-sectional view of the insulating layer 127 and its surrounding region between the two EL layers 113 shown in Figure 8A. Figure 8B shows pixel electrodes 111R and 111G as the pixel electrodes 111. The shapes of the mask layer 118, insulating layer 125, and insulating layer 127 shown in Figure 8B are the same as those in Figure 3A.

[0213] As shown in Figures 8A and 8B, the film thicknesses of the pixel electrodes 111R, 111G, and 111B can be different. For example, it is preferable to set the film thickness in accordance with the optical path length that enhances the light of the color transmitted by the colored layer 132. For example, if the colored layer 132R transmits red light, it is preferable to set the film thickness of the pixel electrode 111R to enhance red light; if the colored layer 132G transmits green light, it is preferable to set the film thickness of the pixel electrode 111G to enhance green light; and if the colored layer 132B transmits blue light, it is preferable to set the film thickness of the pixel electrode 111B to enhance blue light. This makes it possible to realize a microcavity structure and improve the color purity of the light emitted from the sub-pixel 110. Note that even in the configuration shown in Figure 2, for example, the film thicknesses of the pixel electrodes 111R, 111G, and 111B can be different. In this case, even if the film thicknesses of EL layer 113R, EL layer 113G, and EL layer 113B are all the same, a microcavity structure can be realized.

[0214] [Configuration Example 3] Figure 9 shows a modified configuration of the one shown in Figure 2, in which sub-pixel 110R has a colored layer 132R, sub-pixel 110G has a colored layer 132G, and sub-pixel 110B has a colored layer 132B. As shown in Figure 9, the colored layers 132R, 132G, and 132B can be provided on a protective layer 131. In this case, the protective layer 131 is preferably planarized, but it does not have to be planarized.

[0215] In Figure 9, for example, similar to the pixel 108 shown in Figure 2, the EL layer 113R provided on the sub-pixel 110R, the EL layer 113G provided on the sub-pixel 110G, and the EL layer 113B provided on the sub-pixel 110B each emit light of a different color. For example, the EL layer 113R emits red light, the EL layer 113G emits green light, and the EL layer 113B emits blue light. Also, similar to the pixel 108 shown in Figure 2, the film thickness of the EL layer 113R, the film thickness of the EL layer 113G, and the film thickness of the EL layer 113B are different, which enables the realization of a microcavity structure.

[0216] As shown in Figure 9, by providing a colored layer 132 on the sub-pixel 110 and applying a microcavity structure, it is possible to suppress the visibility of ambient light incident on the sub-pixel 110 and reflected by, for example, the pixel electrode 111, even without providing a circular polarizer on the substrate 120. Furthermore, the color purity of the light emitted from the sub-pixel 110 can be increased. Therefore, the display device 100 having the pixel section 107 with the configuration shown in Figure 9 can be a display device with high display quality. Note that even when a colored layer 132 is provided on the sub-pixel 110, it is not necessary to apply a microcavity structure to the sub-pixel 110. Even in this case, the color purity of the light emitted from the sub-pixel 110 can be increased compared to when the colored layer 132 is not provided on the sub-pixel 110.

[0217] As described above, in one aspect of the present invention, by providing a recess 134 in the insulating layer 127 between the two EL layers 113, the stress on the insulating layer 127 can be relieved compared to, for example, the case in which the insulating layer 127 does not have a recess 134. This makes it possible to suppress delamination of the insulating layer 127 and at least one of the layers in contact with the insulating layer 127. Therefore, the display device in one aspect of the present invention can be a highly reliable display device. Furthermore, the display device in one aspect of the present invention can be manufactured using a method with a high yield.

[0218] Furthermore, in one embodiment of the present invention, the display device has an EL layer arranged in an island shape for each light-emitting element, which suppresses the occurrence of leakage current (sometimes referred to as lateral leakage current, transverse leakage current, or lateral leakage current) between sub-pixels. This prevents crosstalk caused by unintended light emission, enabling the realization of a display device with extremely high contrast. In addition, by providing an insulating layer with a tapered shape at the end between adjacent island-shaped EL layers, it is possible to suppress the occurrence of step breaks when forming a common electrode, and to prevent the formation of locally thin areas in the common electrode. This suppresses connection failures caused by separated areas and increases in electrical resistance caused by locally thin areas in the common layer and common electrode. As a result, the display device in one embodiment of the present invention can achieve both high resolution and high display quality.

[0219] [Example of manufacturing method 1] In the following, an example of a method for manufacturing a display device 100 having the configuration shown in Figure 2 and the configuration shown in Figure 7A will be explained using Figures 10A to 18B. Figures 10A to 18B show side by side the cross-sectional view between the dashed-dotted lines A1-A2 and the cross-sectional view between the dashed-dotted lines B1-B2 shown in Figure 1.

[0220] Thin films (insulating films, semiconductor films, and conductive films, etc.) that constitute display devices can be formed using sputtering, chemical vapor deposition (CVD), vacuum deposition, pulsed laser deposition (PLD), or ALD. CVD methods include plasma-enhanced CVD (PECVD) and thermal CVD. One type of thermal CVD is metal-organic vapor deposition (MOCVD).

[0221] Furthermore, thin films (insulating films, semiconductor films, conductive films, etc.) that constitute the display device can be formed by wet film deposition methods such as spin coating, dip coating, spray coating, inkjet printing, dispensing, screen printing, offset printing, doctor knife method, slit coating, roll coating, curtain coating, or knife coating.

[0222] In particular, vacuum processes such as vapor deposition and solution processes such as spin coating and inkjet can be used to fabricate light-emitting elements. Examples of vapor deposition methods include physical vapor deposition (PVD) methods such as sputtering, ion plating, ion beam deposition, molecular beam deposition, or vacuum deposition, and chemical vapor deposition (CVD). Functional layers included in the EL layer (hole injection layer, hole transport layer, hole blocking layer, electron blocking layer, electron transport layer, electron injection layer, and charge generation layer, etc.) can be formed by vapor deposition (e.g., vacuum deposition), coating methods (dip coating, die coating, bar coating, spin coating, or spray coating, etc.), and printing methods (inkjet, screen printing, offset printing, flexographic printing, gravure, or microcontact printing, etc.).

[0223] Furthermore, when processing the thin film that constitutes the display device, it can be processed using, for example, photolithography. Alternatively, the thin film may be processed by nanoimprint lithography, sandblasting, lift-off lithography, etc. In addition, island-shaped thin films may be directly formed by a film deposition method using a shielding mask such as a metal mask.

[0224] There are two main methods of photolithography. One method involves forming a resist mask on the thin film to be processed, then processing the thin film, for example by etching, and removing the resist mask. The other method involves forming a photosensitive thin film, then exposing and developing it to process the thin film into the desired shape.

[0225] In photolithography, the light used for exposure can be, for example, i-line (wavelength 365 nm), g-line (wavelength 436 nm), h-line (wavelength 405 nm), or a mixture thereof. Other options include ultraviolet light, KrF laser light, or ArF laser light. Exposure may also be performed using immersion lithography. Furthermore, extreme ultraviolet (EUV) light or X-rays may be used for exposure. An electron beam can also be used instead of light for exposure. Using extreme ultraviolet light, X-rays, or an electron beam is preferable because it allows for extremely fine processing. Note that a photomask is not required when exposure is performed by scanning a beam such as an electron beam.

[0226] For etching thin films, dry etching, wet etching, or sandblasting methods can be used.

[0227] First, as shown in Figure 10A, an insulating layer 101 is formed on a substrate (not shown). Next, a conductive layer 102 and a conductive layer 109 are formed on the insulating layer 101, and an insulating layer 103 is formed on the insulating layer 101 so as to cover the conductive layers 102 and 109. Next, an insulating layer 104 is formed on the insulating layer 103, and an insulating layer 105 is formed on the insulating layer 104.

[0228] As the substrate, a substrate with sufficient heat resistance to withstand subsequent heat treatment can be used. When using an insulating substrate, glass substrates, quartz substrates, sapphire substrates, ceramic substrates, or organic resin substrates can be used. In addition, semiconductor substrates such as single-crystal semiconductor substrates, polycrystalline semiconductor substrates, compound semiconductor substrates such as silicon-germanium, and SOI substrates made from silicon or silicon carbide can be used.

[0229] Next, as shown in Figure 10A, openings reaching the conductive layer 102 are formed in the insulating layer 105, insulating layer 104, and insulating layer 103. Subsequently, a plug 106 is formed to fill these openings.

[0230] Next, as shown in Figure 10A, a conductive film 111f, which will later become the pixel electrode 111R, pixel electrode 111G, pixel electrode 111B, and conductive layer 123, is formed on the plug 106 and the insulating layer 105. For the formation of the conductive film 111f, for example, sputtering or vacuum deposition can be used. Also, for example, a metallic material can be used as the conductive film 111f.

[0231] Next, as shown in Figure 10B, the conductive film 111f is processed using, for example, photolithography to form the pixel electrode 111R, pixel electrode 111G, pixel electrode 111B, and conductive layer 123. Specifically, for example, after forming a resist mask, a portion of the conductive film 111f is removed by etching. The conductive film 111f can be removed by, for example, dry etching. Here, for example, when a portion of the conductive film 111f is removed by dry etching, a recess may be formed in the region of the insulating layer 105 that does not overlap with the pixel electrode 111.

[0232] Next, it is preferable to perform a hydrophobic treatment on the pixel electrode 111. The hydrophobic treatment can change the surface to be treated from hydrophilic to hydrophobic, or increase the hydrophobicity of the surface to be treated. By performing a hydrophobic treatment on the pixel electrode 111, the adhesion between the pixel electrode 111 and the EL layer 113 formed in a later step can be improved, and film peeling can be suppressed. However, the hydrophobic treatment is not required.

[0233] Hydrophobic treatment can be performed, for example, by fluorine modification of the pixel electrode 111. Fluorine modification can be performed, for example, by treatment with a fluorine-containing gas, heat treatment, plasma treatment in a fluorine-containing gas atmosphere, etc. As the fluorine-containing gas, for example, fluorine gas can be used, and for example, fluorocarbon gas can be used. As the fluorocarbon gas, for example, lower fluorinated carbon gases such as carbon tetrafluoride (CF4) gas, C4F6 gas, C2F6 gas, C4F8 gas, or C5F8 can be used. In addition, as the fluorine-containing gas, for example, SF6 gas, NF3 gas, or CHF3 gas can be used. Furthermore, helium gas, argon gas, hydrogen gas, or oxygen gas can be added to these gases as appropriate.

[0234] Furthermore, the surface of the pixel electrode 111 can be made hydrophobic by performing plasma treatment in a gas atmosphere containing a group 18 element such as argon, followed by treatment with a silylation agent. Hexamethyldisilazane (HMDS) or trimethylsilylimidazole (TMSI) can be used as the silylation agent. In addition, the surface of the pixel electrode 111 can also be made hydrophobic by performing plasma treatment in a gas atmosphere containing a group 18 element such as argon, followed by treatment with a silane coupling agent.

[0235] By performing plasma treatment on the surface of the pixel electrode 111 in a gas atmosphere containing a group 18 element such as argon, damage can be inflicted on the surface of the pixel electrode 111. This makes it easier for methyl groups contained in silylation agents such as HMDS to bond to the surface of the pixel electrode 111. It also makes silane coupling by silane coupling agents easier to occur. Thus, by performing plasma treatment on the surface of the pixel electrode 111 in a gas atmosphere containing a group 18 element such as argon, followed by treatment with a silylation agent or a silane coupling agent, the surface of the pixel electrode 111 can be made hydrophobic.

[0236] Treatment using a silylation agent or silane coupling agent can be carried out by applying the silylation agent or silane coupling agent using, for example, a spin coating method or a dip method. Alternatively, treatment using a silylation agent or silane coupling agent can be carried out by forming a film containing a silylation agent or a film containing a silane coupling agent on the pixel electrode 111, for example, using a gas phase method. In the gas phase method, first, a material containing a silylation agent or a material containing a silane coupling agent is volatilized to include the silylation agent or silane coupling agent in the atmosphere. Subsequently, a substrate on which, for example, the pixel electrode 111 is formed is placed in this atmosphere. This allows a film containing a silylation agent or silane coupling agent to be formed on the pixel electrode 111, thereby hydrophobicizing the surface of the pixel electrode 111.

[0237] Next, as shown in Figure 10C, the EL film 113Rf, which will later become the EL layer 113R, is formed on the pixel electrode 111R, on the pixel electrode 111G, on the pixel electrode 111B, and on the insulating layer 105.

[0238] As shown in Figure 10C, no EL film 113Rf is formed on the conductive layer 123. For example, by using a mask to define the deposition area (also called an area mask or rough metal mask, to distinguish it from a fine metal mask), the EL film 113Rf can be deposited only in the desired area. By employing a deposition process using an area mask and a processing process using a resist mask, a light-emitting element can be manufactured using a relatively simple process.

[0239] The EL film 113Rf can be formed, for example, by a vapor deposition method, specifically a vacuum vapor deposition method. Alternatively, the EL film 113Rf may be formed by methods such as a transfer method, printing method, inkjet method, or coating method.

[0240] The EL film 113Rf has at least one light-emitting film that will later become a light-emitting layer. Furthermore, the EL film 113Rf has a functional film that will later become a functional layer. For example, the EL film 113Rf has a light-emitting film and a functional film on the light-emitting film. The functional film can have one or more of the following: a film that will later become a hole injection layer, a hole transport layer, a hole blocking layer, a charge generation layer, an electron blocking layer, an electron transport layer, and an electron injection layer. Therefore, forming the EL film 113Rf means, for example, forming a light-emitting film and a functional film on the light-emitting film.

[0241] Next, as shown in Figure 10C, a mask film 118Rf, which will later become a mask layer 118R, and a mask film 119Rf, which will later become a mask layer 119R, are formed in order on the EL film 113Rf, the conductive layer 123, and the insulating layer 105, respectively.

[0242] In this embodiment, an example is shown in which the mask film is formed with a two-layer structure consisting of mask film 118Rf and mask film 119Rf, but the mask film may also have a single-layer structure or a laminated structure of three or more layers.

[0243] By providing a mask film on the EL film 113Rf, the damage to the EL film 113Rf during the manufacturing process of the display device can be reduced, thereby improving the reliability of the light-emitting element.

[0244] For the mask film 118Rf, a film with high resistance to the processing conditions of the EL film 113Rf is used, specifically a film with a high etching selectivity ratio with the EL film 113Rf. For the mask film 119Rf, a film with a high etching selectivity ratio with the mask film 118Rf is used.

[0245] Furthermore, the mask films 118Rf and 119Rf are formed at a temperature lower than the heat resistance temperature of the EL film 113Rf. The substrate temperature when forming the mask films 118Rf and 119Rf is typically 200°C or lower, preferably 150°C or lower, more preferably 120°C or lower, more preferably 100°C or lower, and even more preferably 80°C or lower.

[0246] It is preferable to use mask films 118Rf and 119Rf that can be removed by wet etching. By using wet etching, the damage to the EL film 113Rf during processing of mask films 118Rf and 119Rf can be reduced compared to using dry etching.

[0247] For the formation of mask films 118Rf and 119Rf, for example, sputtering, ALD (thermal ALD, PEALD), CVD, and vacuum deposition can be used. Alternatively, they may be formed using the wet film formation method described above.

[0248] Furthermore, it is preferable that the mask film 118Rf, which is formed in contact with the EL film 113Rf, is formed using a method that causes less damage to the EL film 113Rf than the mask film 119Rf. For example, it is preferable to form the mask film 118Rf using the ALD method or vacuum deposition method rather than the sputtering method.

[0249] For the mask film 118Rf and the mask film 119Rf, one or more types can be used, for example, from among metal films, alloy films, metal oxide films, semiconductor films, organic insulating films, and inorganic insulating films.

[0250] The mask film 118Rf and the mask film 119Rf can be made of metallic materials such as gold, silver, platinum, magnesium, nickel, tungsten, chromium, molybdenum, iron, cobalt, copper, palladium, titanium, aluminum, yttrium, zirconium, and tantalum, or alloy materials containing such metallic materials. In particular, it is preferable to use low-melting-point materials such as aluminum or silver. It is preferable to use a metallic material capable of shielding ultraviolet rays in one or both of the mask film 118Rf and the mask film 119Rf, as this can suppress the irradiation of the EL film 113Rf with ultraviolet rays and suppress the degradation of the EL film 113Rf.

[0251] Furthermore, the mask films 118Rf and 119Rf can be made from metal oxides such as In-Ga-Zn oxide, 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), and silicon-containing indium tin oxide, respectively.

[0252] In addition, element M (where M is one or more selected from aluminum, silicon, boron, yttrium, copper, vanadium, beryllium, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, or magnesium) may be used instead of gallium. In particular, it is preferable that M be one or more selected from gallium, aluminum, or yttrium.

[0253] Furthermore, a film containing a material that has light-shielding properties against light, particularly ultraviolet light, can be used as the mask film. For example, a film that reflects ultraviolet light or a film that absorbs ultraviolet light can be used. Various materials can be used as the light-shielding material, such as metals, insulators, semiconductors, and metalloids that have light-shielding properties against ultraviolet light. However, since part or all of the mask film will be removed in a later process, it is preferable that the film be processable by etching, and in particular, that it has good processability.

[0254] For example, semiconductor materials such as silicon or germanium can be used as materials with high affinity to semiconductor manufacturing processes. Alternatively, oxides or nitrides of the above semiconductor materials can be used. Alternatively, nonmetallic (metalloid) materials such as carbon, or compounds thereof, can be used. Alternatively, metals such as titanium, tantalum, tungsten, chromium, and aluminum, or alloys containing one or more of these, can be used. Alternatively, oxides containing the above metals such as titanium oxide or chromium oxide, or nitrides such as titanium nitride, chromium nitride, or tantalum nitride can be used.

[0255] By using a mask film containing a material that has light-shielding properties against ultraviolet light, it is possible to suppress the irradiation of the EL layer with ultraviolet light during the exposure process, for example. By suppressing damage to the EL layer from ultraviolet light, the reliability of the light-emitting element can be improved.

[0256] Furthermore, a film containing a material that has light-shielding properties against ultraviolet rays can be used as the insulating film 125f described later to achieve the same effect.

[0257] Furthermore, various inorganic insulating films that can be used in the protective layer 131 can be used as the mask films 118Rf and 119Rf, respectively. In particular, oxide insulating films are preferred because they have higher adhesion to the EL film 113Rf compared to nitride insulating films. For example, inorganic insulating materials such as aluminum oxide, hafnium oxide, and silicon oxide can be used as the mask films 118Rf and 119Rf, respectively. For example, aluminum oxide films can be formed as the mask films 118Rf and 119Rf using the ALD method. Using the ALD method is preferred because it reduces damage to the substrate (especially the EL layer).

[0258] For example, an inorganic insulating film (e.g., an aluminum oxide film) formed using the ALD method can be used as the mask film 118Rf, and an inorganic film (e.g., an In-Ga-Zn oxide film, an aluminum film, or a tungsten film) formed using the sputtering method can be used as the mask film 119Rf.

[0259] Furthermore, the same inorganic insulating film can be used for both the mask film 118Rf and the insulating layer 125 that is formed later. For example, an aluminum oxide film formed using the ALD method can be used for both the mask film 118Rf and the insulating layer 125. Here, the same film formation conditions may be applied to the mask film 118Rf and the insulating layer 125, or different film formation conditions may be applied to each. For example, by forming the mask film 118Rf under the same conditions as the insulating layer 125, the mask film 118Rf can be made into an insulating layer with high barrier properties against at least one of water and oxygen. On the other hand, since the mask film 118Rf is a layer that will be mostly or completely removed in a later process, it is preferable that it be easy to process. For this reason, it is preferable to form the mask film 118Rf under conditions where the substrate temperature during film formation is lower than that of the insulating layer 125.

[0260] Organic materials may be used in one or both of the mask films 118Rf and 119Rf. For example, as the organic material, a material that is soluble in a chemically stable solvent for at least the film located at the top of the EL film 113Rf may be used. Materials that are soluble in water or alcohol are particularly suitable. When forming such a film, it is preferable to apply the material by a wet film formation method while it is dissolved in a solvent such as water or alcohol, and then perform a heat treatment to evaporate the solvent. At this time, performing the heat treatment under a reduced pressure atmosphere is preferable because it allows the solvent to be removed at a low temperature and in a short time, thereby reducing thermal damage to the EL film 113Rf.

[0261] Mask films 118Rf and 119Rf may be made of polyvinyl alcohol (PVA), polyvinyl butyral, polyvinylpyrrolidone, polyethylene glycol, polyglycerin, pullulan, water-soluble cellulose, alcohol-soluble polyamide resin, or organic resins such as perfluoropolymers.

[0262] For example, an organic film (e.g., a PVA film) formed using either the vapor deposition method or the wet film formation method described above can be used as the mask film 118Rf, and an inorganic film (e.g., a silicon nitride film) formed using the sputtering method can be used as the mask film 119Rf.

[0263] In addition, in one embodiment of the present invention, a portion of the mask film may remain as a mask layer in the display device.

[0264] Next, as shown in Figure 10C, a resist mask 190R is formed on the mask film 119Rf. The resist mask 190R can be formed by applying a photosensitive material (photoresist), followed by exposure and development.

[0265] The resist mask 190R may be made using either a positive-type resist material or a negative-type resist material.

[0266] The resist mask 190R is provided in a position that overlaps with the pixel electrode 111R. It is also preferable to provide the resist mask 190R in a position that overlaps with the conductive layer 123. This helps to suppress damage to the conductive layer 123 during the manufacturing process of the display device. It is not necessary to provide the resist mask 190R on the conductive layer 123. Furthermore, it is preferable to provide the resist mask 190R so as to cover from the edge of the EL film 113Rf to the edge of the conductive layer 123 (the edge on the EL film 113Rf side), as shown in the cross-sectional view between B1 and B2 in Figure 10C.

[0267] Next, as shown in Figure 10D, a portion of the mask film 119Rf is removed using the resist mask 190R to form a mask layer 119R. The mask layer 119R remains on the pixel electrode 111R and on the conductive layer 123. After that, the resist mask 190R is removed. Subsequently, the mask layer 119R is used as a mask (also called a hard mask) to remove a portion of the mask film 118Rf to form a mask layer 118R.

[0268] Mask films 118Rf and 119Rf can be processed by wet etching or dry etching, respectively. It is preferable to process mask films 118Rf and 119Rf by anisotropic etching.

[0269] By using the wet etching method, the damage to the EL film 113Rf during processing of the mask film 118Rf and mask film 119Rf can be reduced compared to using the dry etching method. When using the wet etching method, it is preferable to use chemical solutions such as a developer, aqueous solution of tetramethylammonium hydroxide (TMAH), dilute hydrofluoric acid, oxalic acid, phosphoric acid, acetic acid, nitric acid, or a mixture thereof.

[0270] In the processing of the mask film 119Rf, the EL film 113Rf is not exposed, so there is a wider range of processing methods to choose from compared to the processing of the mask film 118Rf. Specifically, when processing the mask film 119Rf, even if an oxygen-containing gas is used as the etching gas, the degradation of the EL film 113Rf can be suppressed more effectively.

[0271] Furthermore, when using a dry etching method for processing the mask film 118Rf, the degradation of the EL film 113Rf can be suppressed by not using an oxygen-containing gas as the etching gas. When using a dry etching method, it is preferable to use a gas containing a Group 18 element such as CF4, C4F8, SF6, CHF3, Cl2, H2O, BCl3, or He as the etching gas.

[0272] For example, when using an aluminum oxide film formed by the ALD method as the mask film 118Rf, a part of the mask film 118Rf can be removed by a dry etching method using CHF3 and He, or CHF3, He, and CH4. Also, when using an In-Ga-Zn oxide film formed by the sputtering method as the mask film 119Rf, a part of the mask film 119Rf can be removed by a wet etching method using diluted phosphoric acid. Or, a part of the mask film 119Rf may be removed by a dry etching method using CH4 and Ar. Or, a part of the mask film 119Rf can be removed by a wet etching method using diluted phosphoric acid. Also, when using a tungsten film formed by the sputtering method as the mask film 119Rf, a part of the mask film 119Rf can be removed by a dry etching method using SF6, CF4 and O2, or CF4, Cl2 and O2.

[0273] The resist mask 190R can be removed, for example, by ashing using oxygen plasma. Or, oxygen gas and a Group 18 element such as CF4, C4F8, SF6, CHF3, Cl2, H2O, BCl3, or He may be used. Or, the resist mask 190R may be removed by wet etching. At this time, since the mask film 118Rf is located on the outermost surface and the EL film 113Rf is not exposed, damage to the EL film 113Rf can be suppressed in the process of removing the resist mask 190R. Also, the range of selection of the method for removing the resist mask 190R can be widened.

[0274] Subsequently, as shown in FIG. 10D, the EL film 113Rf is processed to form the EL layer 113R. For example, using the mask layer 119R and the mask layer 118R as masks, a part of the EL film 113Rf is removed to form the EL layer 113R.

[0275] As a result, as shown in FIG. 10D, a stacked structure of the EL layer 113R, the mask layer 118R, and the mask layer 119R remains on the pixel electrode 111R. Also, the pixel electrode 111G and the pixel electrode 111B are exposed.

[0276] In FIG. 10D, an example is shown in which the end portion of the EL layer 113R is located outside the end portion of the pixel electrode 111R. By adopting such a configuration, the aperture ratio of the pixel can be increased. Although not shown in FIG. 10D, depending on the etching process, recesses may be formed in the region of the insulating layer 105 that does not overlap with the EL layer 113R.

[0277] Further, by covering the upper surface and the side surface of the pixel electrode 111R with the EL layer 113R, subsequent processes can be performed without exposing the pixel electrode 111R. If the end portion of the pixel electrode 111R is exposed, corrosion may occur, for example, in an etching process. The products generated by the corrosion of the pixel electrode 111R may be unstable. For example, in the case of wet etching, they may dissolve in the solution, and in the case of dry etching, there is a concern that they may scatter into the atmosphere. Due to the dissolution of the products into the solution or the scattering into the atmosphere, for example, the products may adhere to the surface to be processed and the side surface of the EL layer 113R, etc., which may have an adverse effect on the characteristics of the light-emitting element or may form a leakage path between a plurality of light-emitting elements. Also, in the region where the end portion of the pixel electrode 111R is exposed, the adhesion between the layers in contact with each other decreases, and there is a risk that the EL layer 113R or the pixel electrode 111R may be easily peeled off.

[0278] Therefore, by adopting a configuration in which the EL layer 113R covers the upper surface and the side surface of the pixel electrode 111R, for example, the yield and characteristics of the light-emitting element can be improved.

[0279] As described above, it is preferable that the resist mask 190R be provided so as to cover the area between the dashed-dotted lines B1 and B2, from the edge of the EL layer 113R to the edge of the conductive layer 123 (the edge on the EL layer 113R side). As a result, as shown in Figure 10D, the mask layer 118R and the mask layer 119R are provided so as to cover the area between the dashed-dotted lines B1 and B2, from the edge of the EL layer 113R to the edge of the conductive layer 123 (the edge on the EL layer 113R side). Therefore, for example, exposure of the insulating layer 105 between the dashed-dotted lines B1 and B2 can be suppressed. This prevents the insulating layer 105, insulating layer 104, and a part of the insulating layer 103 from being removed by etching or the like, and prevents the conductive layer 109 from being exposed. Therefore, it is possible to suppress the conductive layer 109 from being unintentionally electrically connected to other conductive layers. For example, it is possible to suppress a short circuit between the conductive layer 109 and the common electrode 115 formed in a later process.

[0280] The EL film 113Rf is preferably processed by anisotropic etching. Anisotropic dry etching is particularly preferred. Alternatively, wet etching may be used.

[0281] When using the dry etching method, the degradation of the EL film 113Rf can be suppressed by not using an oxygen-containing gas as the etching gas.

[0282] Furthermore, an etching gas containing oxygen may be used. Including oxygen in the etching gas can increase the etching rate. Therefore, etching can be performed under low power conditions while maintaining a sufficiently fast etching rate. This suppresses damage to the EL film 113Rf. In addition, it suppresses problems such as the adhesion of reaction products generated during etching.

[0283] When using the dry etching method, it is preferable to use an etching gas containing one or more elements from Group 18, such as H2, CF4, C4F8, SF6, CHF3, Cl2, H2O, BCl3, or He, Ar. Alternatively, it is preferable to use an etching gas containing one or more of these elements and oxygen. 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, can be used as the etching gas. Also, for example, a gas containing CF4, He, and oxygen can be used as the etching gas. Furthermore, for example, a gas containing H2 and Ar, and a gas containing oxygen can be used as the etching gas.

[0284] As described above, in one aspect of the present invention, a resist mask 190R is formed on a mask film 119Rf, and a mask layer 119R is formed by removing a portion of the mask film 119Rf using the resist mask 190R. Subsequently, an EL layer 113R is formed by removing a portion of the EL film 113Rf using the mask layer 119R as a mask. Thus, it can be said that an EL layer 113R is formed by processing the EL film 113Rf using a photolithography method. Note that a portion of the EL film 113Rf may be removed using the resist mask 190R. Subsequently, the resist mask 190R may be removed.

[0285] Next, it is preferable to perform a hydrophobic treatment on the pixel electrode 111G, for example. During processing of the EL film 113Rf, the surface state of the pixel electrode 111G may change to hydrophilic. For example, by performing a hydrophobic treatment on the pixel electrode 111G, the adhesion between the pixel electrode 111G and the layer formed in a later process (in this case, the EL layer 113G) can be improved, and film peeling can be suppressed. However, the hydrophobic treatment is not required.

[0286] Next, as shown in Figure 11A, the EL film 113Gf, which will later become the EL layer 113G, is formed on the pixel electrode 111G, the pixel electrode 111B, the mask layer 119R, and the insulating layer 105.

[0287] The EL film 113Gf can be formed by a method similar to that used for forming the EL film 113Rf. Furthermore, like the EL film 113Rf, the EL film 113Gf includes, for example, an emissive film and a functional film on the emissive film. Therefore, forming the EL film 113Gf means forming, for example, an emissive film and a functional film on the emissive film.

[0288] Next, as shown in Figure 11A, a mask film 118Gf, which will later become mask layer 118G, and a mask film 119Gf, which will later become mask layer 119G, are formed in order on the EL film 113Gf and the mask layer 119R, respectively. After that, a resist mask 190G is formed. The materials and formation methods for mask films 118Gf and 119Gf are the same as those applicable to mask films 118Rf and 119Rf. The materials and formation methods for resist mask 190G are the same as those applicable to resist mask 190R.

[0289] The resist mask 190G is positioned to overlap with the pixel electrode 111G.

[0290] Next, as shown in Figure 11B, a portion of the mask film 119Gf is removed using the resist mask 190G to form the mask layer 119G. The mask layer 119G remains on the pixel electrode 111G. After that, the resist mask 190G is removed. Next, the mask layer 119G is used as a mask to remove a portion of the mask film 118Gf to form the mask layer 118G. Next, the EL film 113Gf is processed to form the EL layer 113G. For example, the mask layer 119G and the mask layer 118G are used as masks to remove a portion of the EL film 113Gf to form the EL layer 113G.

[0291] As a result, as shown in Figure 11B, the stacked structure of the EL layer 113G, mask layer 118G, and mask layer 119G remains on the pixel electrode 111G. The mask layer 119R and the pixel electrode 111B are exposed.

[0292] Next, it is preferable to perform a hydrophobic treatment on the pixel electrode 111B, for example. During processing of the EL film 113Gf, the surface state of the pixel electrode 111B may change to hydrophilic. For example, by performing a hydrophobic treatment on the pixel electrode 111B, the adhesion between the pixel electrode 111B and the layer formed in a later process (in this case, the EL layer 113B) can be improved, and film peeling can be suppressed. However, the hydrophobic treatment is not required.

[0293] Next, as shown in Figure 11C, the EL film 113Bf, which will later become the EL layer 113B, is formed on the pixel electrode 111B, the mask layer 119R, the mask layer 119G, and the insulating layer 105.

[0294] The EL film 113Bf can be formed by a method similar to that used for forming the EL film 113Rf. Furthermore, like the EL film 113Rf, the EL film 113Bf includes, for example, an emissive film and a functional film on the emissive film. Therefore, forming the EL film 113Bf means forming, for example, an emissive film and a functional film on the emissive film.

[0295] Next, as shown in Figure 11C, a mask film 118Bf, which will later become mask layer 118B, and a mask film 119Bf, which will later become mask layer 119B, are formed in order on the EL film 113Bf and the mask layer 119R, respectively. After that, the resist mask 190B is formed. The materials and formation methods for mask films 118Bf and 119Bf are the same as those applicable to mask films 118Rf and 119Rf. The materials and formation methods for resist mask 190B are the same as those applicable to resist mask 190R.

[0296] The resist mask 190B is positioned to overlap with the pixel electrode 111B.

[0297] Subsequently, as shown in FIG. 11D, using the resist mask 190B, a part of the mask film 119Bf is removed to form the mask layer 119B. The mask layer 119B remains on the pixel electrode 111B. Thereafter, the resist mask 190B is removed. Subsequently, using the mask layer 119B as a mask, a part of the mask film 118Bf is removed to form the mask layer 118B. Subsequently, the EL film 113Bf is processed to form the EL layer 113B. For example, using the mask layer 119B and the mask layer 118B as masks, a part of the EL film 113Bf is removed to form the EL layer 113B.

[0298] As a result, as shown in FIG. 11D, a stacked structure of the EL layer 113B, the mask layer 118B, and the mask layer 119B remains on the pixel electrode 111B. Also, the mask layer 119R and the mask layer 119G are exposed.

[0299] Note that the side surfaces of the EL layer 113R, the EL layer 113G, and the EL layer 113B are preferably perpendicular or substantially perpendicular to the formation surface, respectively. For example, it is preferable that the angle formed by the formation surface and these side surfaces is 60 degrees or more and 90 degrees or less.

[0300] As described above, the distance between two adjacent ones of the EL layer 113R, the EL layer 113G, and the EL layer 113B formed by using the photolithography method can be narrowed to 8 μm or less, 5 μm or less, 3 μm or less, 2 μm or less, or 1 μm or less. Here, the distance can be defined as, for example, the distance between two opposing end portions of two adjacent ones of the EL layer 113R, the EL layer 113G, and the EL layer 113B. Thus, by narrowing the distance between adjacent EL layers 113, a display device having high definition and a large aperture ratio can be provided.

[0301] Next, as shown in Figure 12A, it is preferable to remove the mask layer 119R, mask layer 119G, and mask layer 119B. Depending on the subsequent process, the mask layer 118R, mask layer 118G, mask layer 118B, mask layer 119R, mask layer 119G, and mask layer 119B may remain in the display device. By removing the mask layer 119R, mask layer 119G, and mask layer 119B at this stage, it is possible to suppress the remaining presence of the mask layer 119R, mask layer 119G, and mask layer 119B in the display device. For example, when conductive materials are used for the mask layer 119R, mask layer 119G, and mask layer 119B, removing the mask layer 119R, mask layer 119G, and mask layer 119B in advance can suppress the generation of leakage current and the formation of capacitance due to the remaining mask layer 119R, mask layer 119G, and mask layer 119B.

[0302] In this embodiment, the case where mask layer 119R, mask layer 119G, and mask layer 119B are removed will be explained as an example, but mask layer 119R, mask layer 119G, and mask layer 119B do not need to be removed.

[0303] The same method as the mask layer processing method can be used for the mask layer removal process. In particular, by using the wet etching method, the damage inflicted on the EL layer 113R, EL layer 113G, and EL layer 113B when removing the mask layer can be reduced compared to when using the dry etching method.

[0304] Alternatively, the mask layer may be removed by dissolving it in a solvent such as water or alcohol. Examples of alcohols include ethyl alcohol, methyl alcohol, isopropyl alcohol (IPA), or glycerin.

[0305] After removing the mask layer, a drying treatment may be performed to remove water contained in EL layer 113R, EL layer 113G, and EL layer 113B, as well as water adsorbed on the surfaces of EL layer 113R, EL layer 113G, and EL layer 113B. 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 to 200°C, preferably 60°C to 150°C, and more preferably 70°C to 120°C. A reduced pressure atmosphere is preferable because it allows drying at a lower temperature.

[0306] Next, as shown in Figure 12B, an insulating film 125f, which will later become the insulating layer 125, is formed to cover the EL layer 113R, EL layer 113G, EL layer 113B, mask layer 118R, mask layer 118G, and mask layer 118B.

[0307] As described later, an insulating film is formed in contact with the upper surface of the insulating film 125f, which will later become the insulating layer 127. For this reason, it is preferable that the upper surface of the insulating film 125f has high affinity for the material used for the insulating film (for example, a photosensitive resin composition containing acrylic resin). To improve this affinity, it is preferable to hydrophobize (or increase the hydrophobicity of) the upper surface of the insulating film 125f by performing a surface treatment. For example, it is preferable to perform the treatment using a silylation agent such as hexamethyldisilazane (HMDS). By hydrophobizing the upper surface of the insulating film 125f in this way, the insulating film 127f can be formed with good adhesion. The aforementioned hydrophobic treatment may also be performed as the surface treatment.

[0308] The insulating film 125f can be the same material used for the mask layer 118R, mask layer 118G, and mask layer 118B. For example, if aluminum oxide is used for the mask layer 118R, mask layer 118G, and mask layer 118B, an aluminum oxide film can also be used for the insulating film 125f. Using the same material for the insulating film 125f and the mask layer 118 is preferable because it allows the processing of the insulating film 125f and the mask layer 118 to be carried out under the same conditions, specifically the same etching conditions, in a later step.

[0309] Next, as shown in Figure 12C, an insulating film 127f, which will later become the insulating layer 127, is formed on the insulating film 125f.

[0310] It is preferable that the insulating film 125f and insulating film 127f are formed using a method that causes minimal damage to the EL layer 113R, EL layer 113G, and EL layer 113B. In particular, since insulating film 125f is formed in contact with the sides of the EL layer 113R, EL layer 113G, and EL layer 113B, it is preferable that it be formed using a method that causes less damage to the EL layer 113R, EL layer 113G, and EL layer 113B than insulating film 127f.

[0311] Furthermore, the insulating film 125f and insulating film 127f are formed at temperatures lower than the heat resistance temperatures of the EL layers 113R, 113G, and 113B, respectively. In addition, by increasing the substrate temperature during film formation of insulating film 125f, it is possible to create a film with a low impurity concentration and high barrier properties against at least one of water and oxygen, even with a thin film thickness.

[0312] The substrate temperature when forming insulating film 125f and insulating film 127f is preferably 60°C or higher, 80°C or higher, 100°C or higher, or 120°C or higher, and 200°C or lower, 180°C or lower, 160°C or lower, 150°C or lower, or 140°C or lower, respectively.

[0313] As the insulating film 125f, it is preferable to form an insulating film with a thickness of 3 nm or more, 5 nm or more, or 10 nm or more, and 200 nm or less, 150 nm or less, 100 nm or less, or 50 nm or less, within the above substrate temperature range.

[0314] The insulating film 125f is preferably formed using, for example, the ALD method. The ALD method is preferable because it can reduce film formation damage and allow for the formation of a highly covering film. For example, it is preferable to form an aluminum oxide film as the insulating film 125f using the ALD method.

[0315] In addition, the insulating film 125f may be formed using a sputtering method, CVD method, or PECVD method, which have a faster deposition rate than the ALD method. This allows for the production of highly reliable display devices with high productivity.

[0316] The insulating film 127f is preferably formed using the wet film formation method described above. The insulating film 127f is preferably formed using a photosensitive material, for example, by spin coating, and more specifically, it is preferably formed using a photosensitive resin composition containing an acrylic resin.

[0317] The insulating film 127f is preferably formed using a resin composition having, for example, a polymer, an acid generator, and a solvent. The polymer is formed using one or more monomers and has a structure in which one or more structural units (also called constituent units) are repeated regularly or irregularly. As the acid generator, one or both of a compound that generates acid upon irradiation with light and a compound that generates acid upon heating can be used. The resin composition may further contain one or more of a photosensitive agent, a sensitizer, a catalyst, an adhesion aid, a surfactant, and an antioxidant.

[0318] Furthermore, it is preferable to perform a heat treatment (also called pre-baking) after the formation of the insulating film 127f. This heat treatment is performed at a temperature lower than the heat resistance temperature of the EL layer 113R, EL layer 113G, and EL layer 113B. The substrate temperature during the heat treatment is preferably 50°C to 200°C, more preferably 60°C to 150°C, and even more preferably 70°C to 120°C. This makes it possible to remove the solvent contained in the insulating film 127f.

[0319] Next, as shown in Figure 13A, exposure is performed to expose a portion of the insulating film 127f to visible light or ultraviolet light. In Figure 13A, the arrows indicate the light used for exposure. Similar notation is used in other drawings showing the exposure process.

[0320] Here, when a positive-type photosensitive resin composition containing acrylic resin is used for the insulating film 127f, visible light or ultraviolet light is irradiated using a mask 132a in the area where the insulating layer 127 will not be formed in a later step. The insulating layer 127 is formed in the area sandwiched between any two of the EL layers 113R, EL layer 113G, and EL layer 113B, and around the conductive layer 123. Specifically, the insulating layer 127 is formed such that, for example, it overlaps with a portion of the upper surface of each of the two EL layers 113 and has an area located between the sides of the two EL layers 113. Therefore, as shown in Figure 13A, visible light or ultraviolet light is irradiated onto the EL layer 113R, EL layer 113G, EL layer 113B, and conductive layer 123 using a mask 132a. In the following, exposure to the insulating film 127f may be referred to as the first exposure.

[0321] The width of the insulating layer 127 to be formed later can be controlled by the area exposed to light during the first exposure. For example, the insulating film 127f can be processed so that it has a portion that overlaps with the upper surface of the pixel electrode 111.

[0322] The light used for the first exposure preferably includes the i-line (wavelength 365 nm). Furthermore, the light used for the first exposure may also include at least one of the g-line (wavelength 436 nm) and the h-line (wavelength 405 nm).

[0323] Here, by providing an oxygen barrier insulating layer, specifically an aluminum oxide film, as one or both of the mask layer 118 and the insulating film 125f, the diffusion of oxygen into the EL layer 113R, EL layer 113G, and EL layer 113B can be suppressed. When the EL layer 113 is irradiated with light (visible light or ultraviolet light), the organic compounds contained in the EL layer 113 may become excited, and their reaction with oxygen in the atmosphere may be promoted. More specifically, when the EL layer 113 is irradiated with light (visible light or ultraviolet light) in an oxygen-containing atmosphere, oxygen may bond to the organic compounds in the EL layer 113. By providing the mask layer 118 and the insulating film 125f on the EL layer 113, the bonding of oxygen in the atmosphere to the organic compounds contained in the EL layer 113 can be suppressed.

[0324] Next, as shown in Figures 13B1 and 13B2, development is performed to remove the exposed area of ​​the insulating film 127f and form the insulating layer 127a. Figure 13B2 is an enlarged view of the EL layer 113G shown in Figure 13B1 and the edge and vicinity of the insulating layer 127a. The insulating layer 127a is formed in the region 133 located between the sides of two adjacent EL layers 113. The insulating layer 127a is also formed in the region surrounding the conductive layer 123. When acrylic resin is used for the insulating film 127f, it is preferable to use an alkaline solution as the developer, for example, TMAH can be used. In the following, the development performed when forming the insulating layer 127a may be referred to as the first development.

[0325] Next, the residue (so-called scum) from the development process may be removed. For example, the residue can be removed by ashing using oxygen plasma.

[0326] Furthermore, etching may be performed to adjust the surface height of the insulating layer 127a. The insulating layer 127a may also be processed, for example, by ashing using oxygen plasma.

[0327] Next, as shown in Figures 14A1 and 14A2, etching is performed using the insulating layer 127a as a mask to thin a portion of the insulating film 125f. Figure 14A2 is an enlarged view of the EL layer 113G shown in Figure 14A1, the edge of the insulating layer 127a, and its vicinity. Hereafter, the above etching process will be referred to as the first etching process.

[0328] The first etching process is performed by a wet etching method. This reduces the damage to the EL layer 113 compared to when the first etching process is performed by a dry etching method. When the first etching process is performed by a wet etching method, a chemical solution that functions as a developer can be used as the etching chemical solution. In this case, it is preferable to use an alkaline solution as the etching chemical solution, for example, TMAH can be used. In other words, a chemical solution with the same components as the developer used when developing the insulating film 127f can be used as the etching chemical solution in the first etching process. In the following, the etching chemical solution used in the first etching process may be referred to as the first chemical solution.

[0329] In Figures 14A1 and 14A2, the thickness of a portion of the insulating film 125f is reduced, while the thicknesses of the mask layers 118R, 118G, and 118B remain unchanged. However, the present invention is not limited to this configuration. For example, depending on the thickness of the insulating film 125f and the thicknesses of the mask layers 118R, 118G, and 118B, a portion of the insulating film 125f may be removed, exposing the mask layers 118R, 118G, and 118B, and the thicknesses of a portion of the mask layers 118R, 118G, and 118B may be reduced. Furthermore, if the insulating film 125f is formed from the same material as the mask layer 118R, mask layer 118G, and mask layer 118B, the boundary between the insulating film 125f and the mask layer 118R, mask layer 118G, and mask layer 118B becomes unclear, and it may be impossible to determine if the film thickness of the mask layer 118R, mask layer 118G, and mask layer 118B has decreased.

[0330] Furthermore, Figures 14A1 and 14A2 show examples where the shape of the insulating layer 127a has not changed from that shown in Figures 13B1 and 13B2, but the present invention is not limited to these examples. For example, the edge of the insulating layer 127a may droop and cover the edge of the insulating film 125f. Also, for example, the edge of the insulating layer 127a may be in contact with the upper surface of the insulating film 125f at a position where it overlaps with the EL layer 113.

[0331] As shown in Figure 14A2, by using the insulating layer 127a, which has a tapered side surface, as a mask for etching, the upper end of the side surface of the insulating film 125f can be made tapered relatively easily.

[0332] Next, as shown in Figure 14B, exposure is performed to expose a portion of the insulating layer 127a to visible light or ultraviolet light. Here, if a positive-type photosensitive resin composition is used for the insulating layer 127a, visible light or ultraviolet light is irradiated using a mask 132b in the area where the recess 134 will be formed in a later step. In the following, exposure of the insulating layer 127a may be referred to as the second exposure.

[0333] The light used for the second exposure can be the same as the light used for the first exposure. For example, it is preferable that the light used for the second exposure includes i-rays.

[0334] Here, the energy density of the second exposure is lower than the energy density of the first exposure. This prevents the insulating layer 127a of the exposed area from disappearing and from being fragmented during the subsequent development process. For example, the energy density of the second exposure is preferably 1 / 2 or less of the energy density of the first exposure, more preferably 1 / 3 or less, and even more preferably 1 / 4 or less. On the other hand, if the energy density of the second exposure is too low, it becomes difficult to form the recess 134 during the subsequent development process. Therefore, the energy density of the second exposure is preferably 1 / 20 or more of the energy density of the first exposure, more preferably 1 / 10 or more, and even more preferably 1 / 7 or more.

[0335] In this specification, the energy density of exposure can be expressed as the product of the power density of the light used for exposure and the exposure time. Here, the unit of power density is, for example, "W / m²". 2 It can be expressed as " and the unit of energy density is, for example, "J / m 2 It can be expressed as ".

[0336] Next, as shown in Figures 15A1 and 15A2, development is performed to thin the film thickness of the exposed area of ​​the insulating layer 127a and form a recess 134. The recess 134 is formed to have, for example, an area that overlaps with the area 133 between the two EL layers 113. Furthermore, etching is performed using the insulating layer 127a as a mask to remove a part of the insulating film 125f and form an insulating layer 125, and thin the film thickness of a part of the mask layer 118R, mask layer 118G, and mask layer 118B. Figure 15A2 is an enlarged view of the EL layer 113G shown in Figure 15A1 and the edge of the insulating layer 127a and its vicinity. Hereafter, the development performed when forming the recess 134 may be referred to as the second development. Also, the etching process described above may be referred to as the second etching process.

[0337] By forming recesses 134 in the insulating layer 127a, the stress on the insulating layer 127a can be relieved in subsequent processes. This makes it possible to suppress one or more of the following: delamination between the EL layer 113 and the mask layer 118, delamination between the mask layer 118 and the insulating layer 125, and delamination between the insulating layer 125 and the insulating layer 127a. Therefore, the method for manufacturing a display device according to one aspect of the present invention can suppress the occurrence of defects and result in a high yield.

[0338] Here, when the second etching process is performed by a wet etching method, the second development and second etching processes can be performed in parallel by using a chemical solution that also functions as a developer as the etching solution. In other words, the second development and the second etching process can be performed simultaneously or combined into the same process. It is preferable to use an alkaline solution as such a chemical solution; for example, TMAH can be used. That is, a chemical solution with the same components as the chemical solution used in the first development and first etching process can be used in the second development and second etching process. In the following, the chemical solution used in the second development and second etching process may be referred to as the second chemical solution.

[0339] When the second development and second etching processes are performed in parallel, the time for the second development and the time for the second etching process are equal. However, if the time for the second etching process is increased, the time for the second development will also increase, and as shown in Figure 15B, the insulating layer 127a in the exposed area during the second exposure may disappear, or the insulating layer 127a may be fragmented. Alternatively, the depth of the recess 134 may increase, which may cause connection problems due to step breaks in the common layer 114 and common electrode 115 formed in a later process, or an increase in electrical resistance due to localized thinning.

[0340] Therefore, in a method for manufacturing a display device according to one aspect of the present invention, a first etching process is performed before exposure to the insulating layer 127a (second exposure) to thin a portion of the insulating film 125f, then the second exposure is performed, followed by the second development and second etching process being carried out in parallel. This shortens the time for the second development and prevents the insulating layer 127a from disappearing in the exposed area during the second exposure, thus preventing the insulating layer 127a from being fragmented. Furthermore, the depth of the recess 134 is increased, which suppresses the occurrence of connection failures due to step breaks or increases in electrical resistance due to localized thinning of the common layer 114 and common electrode 115 formed in a later process. As described above, a method for manufacturing a display device according to one aspect of the present invention can suppress the occurrence of defects and provide a high yield.

[0341] Furthermore, as shown in Figure 15A2, by using the insulating layer 127a, which has a tapered side surface, as a mask for etching, the side surface of the insulating layer 125 and the upper end of the side surface of the mask layer 118 can be made tapered relatively easily.

[0342] As shown in Figures 15A1 and 15A2, in the second etching process, the mask layers 118R, 118G, and 118B are not completely removed, and the etching process is stopped when the film thickness is reduced. By leaving the corresponding mask layers 118R, 118G, and 118B on the EL layers 113R, 113G, and 113B in this way, it is possible to prevent damage to the EL layers 113R, 113G, and 113B in subsequent processing steps.

[0343] In Figures 15A1 and 15A2, the mask layers 118R, 118G, and 118B are configured to have thin films, but the present invention is not limited to this. For example, depending on the film thickness of the insulating film 125f and the film thicknesses of the mask layers 118R, 118G, and 118B, the second etching process may be stopped before the insulating film 125f is processed into the insulating layer 125. Specifically, the second etching process may be stopped after only thinning a portion of the insulating film 125f. Also, if the insulating film 125f is deposited using the same material as the mask layers 118R, 118G, and 118B, the boundary between the insulating film 125f and the mask layers 118R, 118G, and 118B may become unclear. As a result, it may be impossible to determine whether the insulating layer 125 has been formed, or whether the film thickness of the mask layer 118R, mask layer 118G, and mask layer 118B has decreased.

[0344] Furthermore, Figures 15A1 and 15A2 show examples where the shape of the insulating layer 127a has not changed from that shown in Figures 14A1 and 14A2, but the present invention is not limited to these examples. For example, the edge of the insulating layer 127a may droop and cover the edge of the insulating layer 125. Also, for example, the edge of the insulating layer 127a may be in contact with the upper surfaces of the mask layer 118R, mask layer 118G, and mask layer 118B.

[0345] As mentioned above, by providing oxygen barrier insulating layers (for example, an aluminum oxide film) as mask layers 118R, 118G, and 118B, the diffusion of oxygen into EL layers 113R, 113G, and 113B can be reduced.

[0346] Next, as shown in Figures 16A and 16B, a heat treatment (also called post-bake) is performed. As shown in Figures 16A and 16B, by performing the heat treatment, the insulating layer 127a can be deformed into an insulating layer 127 having a tapered shape on its side. Furthermore, if a thermosetting resin is used as the insulating layer 127a, for example, the insulating layer 127a can be hardened by the heat treatment.

[0347] As mentioned above, the shape of the insulating layer 127a may have already changed and have a tapered shape on its side surface by the time the first or second etching process is completed. This heat treatment is performed at a temperature lower than the heat resistance temperature of the EL layer. The heat treatment can be performed at a substrate temperature of 50°C to 200°C, preferably 60°C to 150°C, and more preferably 70°C to 130°C. The heating atmosphere may be an atmospheric atmosphere or an inert gas atmosphere. The heating atmosphere may also be an atmospheric pressure atmosphere or a reduced pressure atmosphere. A reduced pressure atmosphere is preferable because it allows drying at a lower temperature. It is preferable to use a higher substrate temperature for this heat treatment than for the heat treatment (pre-bake) after the formation of the insulating film 127f. This improves the adhesion between the insulating layer 127 and the insulating layer 125, and also improves the corrosion resistance of the insulating layer 127. Figure 16B is an enlarged view of the EL layer 113G and the edge and vicinity of the insulating layer 127 shown in Figure 16A.

[0348] As described above, in one embodiment of the present invention, a highly heat-resistant material is used for the light-emitting element. Therefore, the pre-bake temperature and post-bake temperature can be set to 100°C or higher, 120°C or higher, or 140°C or higher, respectively. This further improves the adhesion between the insulating layer 127 and the insulating layer 125, and also improves the corrosion resistance of the insulating layer 127. Furthermore, it broadens the range of materials that can be used as the insulating layer 127. In addition, for example, by sufficiently removing the solvent contained in the insulating layer 127, it is possible to suppress the penetration of impurities such as water and oxygen into the EL layer.

[0349] In the second etching process, by not completely removing mask layers 118R, 118G, and 118B, but leaving them in a thinned state, it is possible to prevent damage and degradation of EL layers 113R, 113G, and 113B during the heat treatment. Therefore, the reliability of the light-emitting element can be improved.

[0350] Furthermore, depending on the material of the insulating layer 127, as well as the post-bake temperature, time, and atmosphere, a concave curved shape may be formed on the side surface of the insulating layer 127, as shown in Figures 5A and 5B. For example, the higher the temperature or the longer the post-bake conditions, the more likely the shape of the insulating layer 127 is to change, and a concave curved shape may be formed.

[0351] Next, as shown in Figures 17A and 17B, etching is performed using the insulating layer 127 as a mask to remove a portion of the mask layer 118R, mask layer 118G, and mask layer 118B. In some cases, a portion of the insulating layer 125 may also be removed. As a result, openings are formed in the mask layers 118R, 118G, and 118B, respectively, exposing the upper surfaces of the EL layer 113R, EL layer 113G, EL layer 113B, and conductive layer 123. Figure 17B is a magnified view of the EL layer 113G and the edge and vicinity of the insulating layer 127 shown in Figure 17A. Hereafter, the etching process using the insulating layer 127 as a mask may be referred to as the third etching process.

[0352] The edges of the insulating layer 125 are covered with the insulating layer 127. Figures 17A and 17B also show an example where the insulating layer 127 covers a portion of the edge of the mask layer 118G (specifically, the tapered portion formed by the second etching process), while the tapered portion formed by the third etching process is exposed. In other words, this corresponds to the structure shown in Figures 3A and 3B.

[0353] Furthermore, as shown in Figures 4A, 4B, or 6A, 6B, the insulating layer 127 may cover the entire edge of the mask layer 118G. For example, the edge of the insulating layer 127 may hang down and cover the edge of the mask layer 118G. Also, for example, the edge of the insulating layer 127 may be in contact with at least one upper surface of the EL layer 113R, EL layer 113G, and EL layer 113B.

[0354] The third etching process is performed by wet etching. By using the wet etching method, damage to the EL layer 113R, EL layer 113G, and EL layer 113B can be reduced compared to when using the dry etching method. When the third etching process is performed by wet etching, a chemical solution that functions as a developer can be used as the etching chemical solution. In this case, it is preferable to use an alkaline solution as the etching chemical solution, for example, TMAH can be used. In other words, a chemical solution with the same components as the developer used when developing the insulating film 127f can be used as the etching chemical solution in the third etching process. In the following, the etching chemical solution used in the third etching process may be referred to as the third chemical solution.

[0355] As described above, in the method for manufacturing a display device according to one aspect of the present invention, the first chemical solution used in the first etching process performed after the formation of the insulating layer 127a and before the formation of the recess 134, the second chemical solution used in the second etching process performed in parallel with the formation of the recess 134, and the third chemical solution used in the third etching process can all be chemical solutions that function as a developer. Therefore, the first to third chemical solutions can all be chemical solutions with the same components.

[0356] Here, since the insulating layer 127 is hardened by post-bake, the insulating layer 127 is not processed even if a developer is used as the third chemical. Therefore, by performing a post-bake treatment, it is possible to prevent the recesses 134 in the insulating layer 127 from becoming deeper due to the third etching treatment.

[0357] As described above, by providing insulating layer 127, insulating layer 125, mask layer 118R, mask layer 118G, and mask layer 118B, connection failures caused by the divided portion and increases in electrical resistance caused by locally thin film thickness can be suppressed between each light-emitting element in the common layer 114 and common electrode 115. As a result, a display device according to one embodiment of the present invention can improve display quality.

[0358] Furthermore, after exposing a portion of the EL layer 113R, EL layer 113G, and EL layer 113B, a further heat treatment may be performed. This heat treatment can remove water contained in the EL layer 113 and water adsorbed on the surface of the EL layer 113. In addition, this heat treatment may change the shape of the insulating layer 127. Specifically, the insulating layer 127 may spread to cover at least one of the following: the edge of the insulating layer 125, the edge of the mask layer 118R, mask layer 118G, and mask layer 118B, and the upper surface of the EL layer 113R, EL layer 113G, and EL layer 113B. For example, the insulating layer 127 may take on the shape shown in Figures 4A and 4B. For example, the 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 to 200°C, preferably 60°C to 150°C, and more preferably 70°C to 120°C. Using a reduced pressure atmosphere is preferable because it allows for dehydration at a lower temperature. However, it is preferable to appropriately set the temperature range for the above heat treatment, taking into account the heat resistance temperature of the EL layer 113. When considering the heat resistance temperature of the EL layer 113, a temperature of 70°C to 120°C is particularly preferable within the above temperature range.

[0359] Next, as shown in Figure 18A, a common layer 114 is formed on the EL layer 113R, EL layer 113G, EL layer 113B, conductive layer 123, and insulating layer 127. The common layer 114 can be formed by methods such as vapor deposition (including vacuum deposition), transfer, printing, inkjet, or coating.

[0360] Next, as shown in Figure 18A, a common electrode 115 is formed on the common layer 114. The common electrode 115 can be formed by sputtering or vacuum deposition. Alternatively, the common electrode 115 may be formed by laminating a film formed by deposition with a film formed by sputtering.

[0361] The common electrode 115 can be formed continuously after the common layer 114 has been formed, without any intermediate steps such as etching. For example, after forming the common layer 114 in a vacuum, the common electrode 115 can be formed in a vacuum without removing the substrate to the atmosphere. In other words, the common layer 114 and the common electrode 115 can be formed in a continuous vacuum. As a result, the underside of the common electrode 115 can be made cleaner than when the display device 100 does not have a common layer 114. Therefore, the light-emitting element 130 can be made into a light-emitting element with high reliability and good characteristics.

[0362] Next, as shown in Figure 18B, a protective layer 131 is formed on the common electrode 115. The protective layer 131 can be formed by methods such as vacuum deposition, sputtering, CVD, or ALD.

[0363] Next, by using the resin layer 122 to bond the substrate 120 onto the protective layer 131, a display device having the configuration shown in Figure 2 and the configuration shown in Figure 7A can be manufactured.

[0364] In the method for manufacturing a display device according to one aspect of the present invention, a recess 134 is formed in the insulating layer 127a. This makes it possible to suppress one or more of the following: delamination between the EL layer 113 and the mask layer 118, delamination between the mask layer 118 and the insulating layer 125, and delamination between the insulating layer 125 and the insulating layer 127a.

[0365] Furthermore, in a method for manufacturing a display device according to one aspect of the present invention, a first etching process is performed before the second exposure to form the recess 134 to thin a portion of the insulating film 125f, then the second exposure is performed, and thereafter the second development and second etching process are performed in parallel. By performing the first etching process, the time for the second development process, which is the process of forming the recess 134, can be shortened, and the insulating layer 127a in the exposed area during the second exposure will not disappear, preventing the insulating layer 127a from being fragmented. In addition, the depth of the recess 134 is increased, which can suppress the occurrence of connection failures due to step breaks or increases in electrical resistance due to localized thinning of the common layer 114 and common electrode 115 formed in a later process.

[0366] Based on the above, the method for manufacturing a display device according to one aspect of the present invention can suppress the occurrence of defects and result in a manufacturing method with a high yield.

[0367] Furthermore, in a method for manufacturing a display device according to one aspect of the present invention, the EL layers 113R, 113G, and 113B are formed not using a fine metal mask, but by processing after depositing a film on one surface, so that island-like layers can be formed with a uniform thickness. This makes it possible to realize a high-definition display device or a display device with a high aperture ratio. Moreover, even if the resolution or aperture ratio is high and the distance between subpixels is extremely short, it is possible to suppress contact between adjacent subpixels between the EL layers 113R, 113G, and 113B. Therefore, it is possible to suppress the generation of leakage current between subpixels. This makes it possible to prevent crosstalk caused by unintended light emission and realize a display device with extremely high contrast.

[0368] Furthermore, by providing an insulating layer 127 having a tapered shape at its end between adjacent EL layers 113, it is possible to suppress the occurrence of step breaks during the formation of the common electrode 115 and to prevent the formation of locally thin areas in the common electrode 115. This suppresses connection failures caused by the divided areas and increases in electrical resistance caused by locally thin areas in the common layer 114 and the common electrode 115. Therefore, a display device according to one aspect of the present invention can achieve both high resolution and high display quality.

[0369] [Example of manufacturing method 2] In the following, examples of methods for manufacturing a display device 100 having the configuration shown in Figure 8A and the configuration shown in Figure 7A will be explained using Figures 19A to 19C. Figures 19A to 19C show side by side the cross-sectional view between the dashed lines A1-A2 and the cross-sectional view between the dashed lines B1-B2 shown in Figure 1. Note that the explanation will mainly focus on methods different from those explained in Figures 10A to 18B, and methods identical to those explained in Figures 10A to 18B will be omitted as appropriate.

[0370] First, the same process as shown in Figures 10A and 10B is performed. As a result, as shown in Figure 19A, the pixel electrode 111R, pixel electrode 111G, pixel electrode 111B, and conductive layer 123 are formed on the plug 106 and the insulating layer 105. Here, by repeatedly performing the conductive film deposition process, which is the same process as shown in Figure 10A, and the patterning process, which is the same process as shown in Figure 10B, the film thickness of the pixel electrode 111R, the film thickness of the pixel electrode 111G, and the film thickness of the pixel electrode 111B can be made to differ from each other. For example, by performing the conductive film deposition and patterning process three times, the film thickness of the pixel electrode 111R, the film thickness of the pixel electrode 111G, and the film thickness of the pixel electrode 111B can be made to differ from each other.

[0371] Next, as shown in Figure 19B, an EL film 113f, which will later become the EL layer 113, is formed on the pixel electrode 111R, on the pixel electrode 111G, on the pixel electrode 111B, and on the insulating layer 105. Subsequently, a mask film 118f, which will later become the mask layer 118, and a mask film 119f, which will later become the mask layer 119, are formed in order on the EL film 113f, on the conductive layer 123, and on the insulating layer 105.

[0372] Next, as shown in Figure 19B, a resist mask 190 is formed on the mask film 119f. The resist mask 190 is provided at positions overlapping with the pixel electrode 111R, positions overlapping with the pixel electrode 111G, and positions overlapping with the pixel electrode 111B. It is also preferable to provide the resist mask 190 at positions overlapping with the conductive layer 123. Furthermore, as shown in the cross-sectional view between B1 and B2 in Figure 19B, it is preferable to provide the resist mask 190 so as to cover from the edge of the EL film 113f to the edge of the conductive layer 123 (the edge on the EL film 113f side).

[0373] Next, as shown in Figure 19C, a portion of the mask film 119f is removed using the resist mask 190 to form a mask layer 119. The mask layer 119 remains on the pixel electrode 111R, pixel electrode 111G, pixel electrode 111B, and conductive layer 123. After that, the resist mask 190 is removed. Subsequently, the mask layer 119 is used as a mask (also called a hard mask) to remove a portion of the mask film 118f to form a mask layer 118.

[0374] Next, as shown in Figure 19C, the EL film 113f is processed to form the EL layer 113. For example, mask layer 119 and mask layer 118 are used as a hard mask to remove a portion of the EL film 113f and form the EL layer 113.

[0375] As a result, as shown in Figure 19C, the stacked structure of the EL layer 113, mask layer 118, and mask layer 119 remains on the pixel electrode 111R, pixel electrode 111G, and pixel electrode 111B, respectively. Furthermore, between the dashed lines B1 and B2, the mask layer 118 and mask layer 119 can be provided so as to cover from the end of the EL layer 113 to the end of the conductive layer 123 (the end on the EL layer 113 side).

[0376] Next, the same process as shown in Figures 12A to 18B is carried out. Note that the protective layer 131 can be flattened. Subsequently, a colored layer 132R, a colored layer 132G, and a colored layer 132B are formed on the protective layer 131. Then, by laminating the substrate 120 onto the colored layer 132 using the resin layer 122, a display device having the configuration shown in Figure 8A and the configuration shown in Figure 7A can be manufactured.

[0377] As described above, the display device 100 having the configuration shown in Figure 8A can be manufactured by performing the formation and processing of the EL film 113f, mask film 118f, and mask film 119f in a single step, without the need to perform the process for each color. Therefore, the manufacturing process of the display device 100 can be simplified. Consequently, the manufacturing cost of the display device 100 can be reduced, making the display device 100 a low-cost display device.

[0378] This embodiment can be combined with other embodiments as appropriate. Furthermore, if multiple configuration examples are shown within a single embodiment in this specification, these configuration examples can be combined as appropriate.

[0379] (Embodiment 2) This embodiment describes an example of a pixel layout for a display device according to one aspect of the present invention.

[0380] There are no particular limitations on the arrangement of subpixels 110 in the display device 100, which is a display device according to one aspect of the present invention, and various methods can be applied. Examples of arrangements for subpixels 110 include stripe arrangements, S-stripe arrangements, matrix arrangements, delta arrangements, Bayer arrangements, or pentile arrangements.

[0381] Furthermore, the top surface shape of the sub-pixel 110 can be, for example, a polygon such as a triangle, quadrilateral (including rectangles and squares), or pentagon, or a polygon with rounded corners, or an ellipse or a circle. Here, the top surface shape of the sub-pixel 110 corresponds to the top surface shape of the light-emitting region of the light-emitting element 130.

[0382] The pixel 108 shown in Figure 20A has an S-stripe array applied to it. The pixel 108 shown in Figure 20A is composed of three subpixels: subpixel 110R, subpixel 110G, and subpixel 110B.

[0383] The pixel 108 shown in Figure 20B includes a sub-pixel 110R with a roughly trapezoidal top surface shape with rounded corners, a sub-pixel 110G with a roughly triangular top surface shape with rounded corners, and a sub-pixel 110B with a roughly quadrilateral or hexagonal top surface shape with rounded corners. Furthermore, sub-pixel 110R has a larger light-emitting area than sub-pixel 110G. In this way, the shape and size of each sub-pixel can be determined independently. For example, sub-pixels with more reliable light-emitting elements can be made smaller in size.

[0384] A Pentile array is applied to pixels 124a and 124b shown in Figure 20C. Figure 20C shows an example in which pixels 124a having sub-pixels 110R and 110G and pixels 124b having sub-pixels 110G and 110B are arranged alternately.

[0385] Pixels 124a and 124b, shown in Figures 20D and 20E, have a delta array applied. Pixel 124a has two subpixels (subpixels 110R and 110G) in the top row (1st row) and one subpixel (subpixel 110B) in the bottom row (2nd row). Pixel 124b has one subpixel (subpixel 110B) in the top row (1st row) and two subpixels (subpixels 110R and 110G) in the bottom row (2nd row).

[0386] Figure 20D shows an example where each subpixel has a roughly square top shape with rounded corners, and Figure 20E shows an example where each subpixel has a circular top shape.

[0387] Figure 20F shows an example where the subpixels of each color are arranged in a zigzag pattern. Specifically, in a plan view, the upper edges of two subpixels aligned in the column direction (for example, subpixel 110R and subpixel 110G, or subpixel 110G and subpixel 110B) are offset.

[0388] In photolithography, the finer the pattern being processed, the more significant the effects of light diffraction become. This compromises the fidelity of transferring the photomask pattern through exposure, making it difficult to process the resist mask into the desired shape. Therefore, even if the photomask pattern is rectangular, patterns with rounded corners are likely to form. Consequently, the top surface shape of subpixels may be a polygon with rounded corners, an ellipse, or a circle.

[0389] Furthermore, in a method for manufacturing a display device according to one aspect of the present invention, the EL layer is processed using a resist mask. The resist film formed on the EL layer needs to be cured at a temperature lower than the heat resistance temperature of the EL layer. Therefore, depending on the heat resistance temperature of the EL layer material and the curing temperature of the resist material, the curing of the resist film may be insufficient. A resist film that is not sufficiently cured may take on a shape that deviates from the desired shape during processing. As a result, the top surface shape of the EL layer may become a polygon with rounded corners, an ellipse, or a circle. For example, if an attempt is made to form a resist mask with a square top surface, a resist mask with a circular top surface may be formed, resulting in a circular top surface shape for the EL layer.

[0390] Furthermore, in order to achieve the desired shape of the upper surface of the EL layer, a technique (OPC (Optical Proximity Correction) technique) may be used to pre-correct the mask pattern so that the design pattern and the transferred pattern match. Specifically, in the OPC technique, for example, a correction pattern is added to the corners of the shape on the mask pattern.

[0391] Furthermore, even in pixel 108 to which the stripe arrangement shown in Figure 1 is applied, the order of the subpixels is not particularly limited. For example, they may be arranged in the order of subpixel 110G, subpixel 110R, and subpixel 110B, as shown in Figure 20G.

[0392] As shown in Figures 21A to 21H, pixel 108 can be configured to have sub-pixels 110R, 110G, and 110B, as well as sub-pixel 110W. Here, sub-pixel 110W can exhibit white light.

[0393] Pixel 108, shown in Figures 21A to 21C, has a stripe arrangement applied to it.

[0394] Figure 21A shows an example where each subpixel has a rectangular top surface shape, Figure 21B shows an example where each subpixel has a top surface shape formed by connecting two semicircles and a rectangle, and Figure 21C shows an example where each subpixel has an elliptical top surface shape.

[0395] Pixel 108, shown in Figures 21D to 21F, has a matrix array applied to it.

[0396] Figure 21D shows an example where each subpixel has a square top surface shape, Figure 21E shows an example where each subpixel has a roughly square top surface shape with rounded corners, and Figure 21F shows an example where each subpixel has a circular top surface shape.

[0397] Figures 21G and 21H show an example where one pixel 108 is composed of 2 rows and 3 columns.

[0398] Pixel 108, shown in Figure 21G, has three subpixels (subpixels 110R, 110G, and 110B) in the top row (row 1) and one subpixel (subpixel 110W) in the bottom row (row 2). In other words, pixel 108 has subpixel 110R in the left column (column 1), subpixel 110G in the middle column (column 2), subpixel 110B in the right column (column 3), and subpixel 110W across these three columns.

[0399] Pixel 108, shown in Figure 21H, has three subpixels (subpixels 110R, 110G, and 110B) in the top row (1st row) and three subpixels 110W in the bottom row (2nd row). In other words, pixel 108 has subpixels 110R and 110W in the left column (1st column), subpixels 110G and 110W in the middle column (2nd column), and subpixels 110B and 110W in the right column (3rd column). As shown in Figure 21H, by aligning the arrangement of subpixels in the top row and bottom row, it becomes possible to efficiently remove dust that may be generated during the manufacturing process, for example. Therefore, a display device with high display quality can be provided.

[0400] The pixel 108 shown in Figures 21A to 21H is composed of four subpixels: subpixel 110R, subpixel 110G, subpixel 110B, and subpixel 110W. Each of the subpixels 110R, 110G, 110B, and 110W has a light-emitting element that emits light of a different color.

[0401] As described above, in one aspect of the present invention, various layouts can be applied to pixels that consist of subpixels having light-emitting elements.

[0402] This embodiment can be combined with other embodiments as appropriate. Furthermore, if multiple configuration examples are shown within a single embodiment in this specification, these configuration examples can be combined as appropriate.

[0403] (Embodiment 3) This embodiment describes a display device according to one aspect of the present invention.

[0404] The display device of this embodiment can be a high-definition display device. Therefore, the display device of this embodiment can be used, for example, as a display unit for information terminals (wearable devices) such as wristwatches and bracelets, and as a display unit for wearable devices that can be worn on the head, such as VR devices such as head-mounted displays (HMDs) and AR devices such as glasses.

[0405] Furthermore, the display device of this embodiment can be a high-resolution display device or a large-screen display device. Therefore, the display device of this embodiment can be used in electronic devices with relatively large screens, such as television equipment, desktop or notebook personal computers, computer monitors, digital signage, and large game machines such as pachinko machines, as well as in the display units of digital cameras, digital video cameras, digital photo frames, mobile phones, portable game consoles, personal information terminals, and audio playback devices.

[0406] [Display Module] Figure 22A shows a perspective view of the display module 280. The display module 280 includes a display device 100A and an FPC 290. Note that the display device included in the display module 280 is not limited to display device 100A, but may be any of the display devices 100B to 100F described later.

[0407] The display module 280 has substrates 291 and 292. The display module 280 has a display unit 281. The display unit 281 is an area in the display module 280 that displays an image, and is an area in which light from each pixel provided in the pixel unit 284, which will be described later, can be seen.

[0408] Figure 22B shows a schematic perspective view illustrating the configuration of the substrate 291. On the substrate 291, a circuit section 282, a pixel circuit section 283 on the circuit section 282, and a pixel section 284 on the pixel circuit section 283 are stacked. In addition, a terminal section 285 for connecting to the FPC 290 is provided in the portion of the substrate 291 that does not overlap with the pixel section 284. The terminal section 285 and the circuit section 282 are electrically connected by a wiring section 286, which is composed of multiple wires.

[0409] The pixel section 284 has a plurality of pixels 284a arranged periodically. A magnified view of one pixel 284a is shown on the right side of Figure 22B. Various configurations described in the previous embodiment can be applied to the pixel 284a. Figure 22B shows an example where the pixel 284a has the same configuration as the pixel 108 shown in Figure 1.

[0410] The pixel circuit section 283 has a plurality of pixel circuits 283a arranged periodically.

[0411] A single pixel circuit 283a is a circuit that controls the driving of multiple elements in a single pixel 284a. A single pixel circuit 283a can be configured to have three circuits that control the light emission of a single light-emitting element. For example, a single pixel circuit 283a can be configured to have at least one selection transistor, one current control transistor (driving transistor), and a capacitor for each light-emitting element. In this case, a gate signal is input to the gate of the selection transistor, and a video signal is input to the source or drain. This realizes an active-matrix type display device.

[0412] The circuit section 282 has circuits for driving each pixel circuit 283a of the pixel circuit section 283. For example, it is preferable to have one or both of a scan line drive circuit and a signal line drive circuit. In addition, it may have at least one of the following: an arithmetic circuit, a memory circuit, and a power supply circuit.

[0413] The FPC290 functions as wiring for supplying video signals or power potential, etc., to the circuit section 282 from an external source. An IC may also be mounted on the FPC290.

[0414] The display module 280 can be configured such that one or both of the pixel circuit section 283 and the circuit section 282 are stacked on the lower side of the pixel section 284, thereby enabling an extremely high aperture ratio (effective display area ratio) of the display section 281. For example, the aperture ratio of the display section 281 can be 40% or more and less than 100%, preferably 50% or more and 95%, and more preferably 60% or more and 95%. Furthermore, it is possible to arrange the pixels 284a at an extremely high density, enabling an extremely high resolution of the display section 281. For example, it is preferable that the pixels 284a are arranged in the display section 281 with a resolution of 20000 ppi or more, preferably 3000 ppi or more, more preferably 5000 ppi or more, and even more preferably 6000 ppi or more, and a resolution of 20000 ppi or less, or 30000 ppi or less.

[0415] Because such a display module 280 is extremely high-resolution, it can be suitably used in VR devices such as HMDs or AR devices such as glasses. For example, even in a configuration where the display part of the display module 280 is viewed through lenses, the display module 280 has an extremely high-resolution display part 281, so even when the display part is magnified with lenses, pixels are not visible, and a highly immersive display can be achieved. Furthermore, the display module 280 is not limited to this and can be suitably used in electronic devices with relatively small display parts. For example, it can be suitably used in the display part of wearable electronic devices such as watches.

[0416] [Display device 100A] The display device 100A shown in Figure 23A includes a substrate 301, light-emitting elements 130R, 130G, 130B, a capacitor 240, and a transistor 310.

[0417] Substrate 301 corresponds to substrate 291 in Figures 22A and 22B. Transistor 310 is a transistor having a channel formation region in substrate 301. For example, a semiconductor substrate such as a single-crystal silicon substrate can be used as substrate 301. Transistor 310 has a part of 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 substrate 301 and the conductive layer 311 and functions as a gate insulating layer. The low-resistance region 312 is a region of substrate 301 doped with impurities and functions as a source or drain. The insulating layer 314 is provided covering the side surface of the conductive layer 311.

[0418] Furthermore, an element isolation layer 315 is provided between two adjacent transistors 310 so as to be embedded in the substrate 301.

[0419] Furthermore, an insulating layer 261 is provided covering the transistor 310, and a capacitance 240 is provided on the insulating layer 261.

[0420] The capacitor 240 has a conductive layer 241, a conductive layer 245, and an insulating layer 243 located between them. The conductive layer 241 acts as one electrode of the capacitor 240, the conductive layer 245 acts as the other electrode of the capacitor 240, and the insulating layer 243 acts as the dielectric of the capacitor 240.

[0421] The conductive layer 241 is provided on the insulating layer 261 and embedded in the insulating layer 254. The conductive layer 241 is electrically connected to either the source or drain of the transistor 310 by a plug 271 embedded in the insulating layer 261. The insulating layer 243 is provided covering the conductive layer 241. The conductive layer 245 is provided in the region that overlaps with the conductive layer 241 via the insulating layer 243.

[0422] An insulating layer 255 is provided covering the capacitance 240, an insulating layer 104 is provided on the insulating layer 255, and an insulating layer 105 is provided on the insulating layer 104. Light-emitting elements 130R, 130G, and 130B are provided on the insulating layer 105. Figure 23A shows an example in which light-emitting elements 130R, 130G, and 130B have the laminated structure shown in Figure 2. An insulator is provided in the region between adjacent light-emitting elements. For example, in Figure 23A, an insulating layer 125 and an insulating layer 127 on the insulating layer 125 are provided in this region.

[0423] A mask layer 118R is located on the EL layer 113R of the light-emitting element 130R, a mask layer 118G is located on the EL layer 113G of the light-emitting element 130G, and a mask layer 118B is located on the EL layer 113B of the light-emitting element 130B.

[0424] Pixel electrodes 111R, 111G, and 111B are electrically connected to either the source or drain of transistor 310 by insulating layer 243, insulating layer 255, insulating layer 104, a plug 256 embedded in insulating layer 105, a conductive layer 241 embedded in insulating layer 254, and a plug 271 embedded in insulating layer 261. The height of the top surface of insulating layer 105 and the height of the top surface of plug 256 are equal or approximately equal. Various conductive materials can be used for the plugs.

[0425] Furthermore, a protective layer 131 is provided on the light-emitting element 130R, light-emitting element 130G, and light-emitting element 130B. A substrate 120 is bonded to the protective layer 131 by a resin layer 122. Details of the components from the light-emitting element 130 to the substrate 120 can be found in Embodiment 1. The substrate 120 corresponds to the substrate 292 in Figure 22A.

[0426] Figure 23B is a modified example of the display device 100A shown in Figure 23A. The display device shown in Figure 23B has a colored layer 132R, a colored layer 132G, and a colored layer 132B, and the light-emitting element 130 has a region that overlaps with one of the colored layers 132R, 132G, and 132B. For details of the components from the insulating layer 104 to the substrate 120 in the display device shown in Figure 23B, please refer to Figure 8A. In the display device shown in Figure 23B, the light-emitting element 130 can emit, for example, white light. Also, for example, the colored layer 132R can transmit red light, the colored layer 132G can transmit green light, and the colored layer 132B can transmit blue light.

[0427] [Display device 100B] The display device 100B shown in Figure 24 has a configuration in which transistors 310A and 310B, each with a channel formed on a semiconductor substrate, are stacked. In the following description of the display device, parts that are the same as those described earlier may be omitted.

[0428] The display device 100B has a configuration in which a substrate 301B on which a transistor 310B, a capacitor 240, and a light-emitting element are provided, and a substrate 301A on which a transistor 310A is provided are bonded together.

[0429] Here, it is preferable to provide an insulating layer 345 on the lower surface of the substrate 301B. It is also preferable to provide an insulating layer 346 on top of the insulating layer 261 provided on the substrate 301A. The insulating layers 345 and 346 are insulating layers that function as protective layers and can suppress the diffusion of impurities into the substrates 301B and 301A. As the insulating layers 345 and 346, inorganic insulating films that can be used for the protective layer 131 can be used.

[0430] A plug 343 is provided on the substrate 301B, penetrating both the substrate 301B and the insulating layer 345. It is preferable to provide an insulating layer 344 covering the sides of the plug 343. The insulating layer 344 functions as a protective layer and can suppress the diffusion of impurities into the substrate 301B. An inorganic insulating film, usable for the protective layer 131, can be used as the insulating layer 344.

[0431] Furthermore, a conductive layer 342 is provided on the back side of substrate 301B (the front side of substrate 301A), beneath the insulating layer 345. Preferably, the conductive layer 342 is provided so as to be embedded in the insulating layer 335. Also, preferably, the undersides of the conductive layer 342 and the insulating layer 335 are flattened. Here, the conductive layer 342 is electrically connected to the plug 343.

[0432] On the other hand, a conductive layer 341 is provided on an insulating layer 346 between substrates 301A and 301B. Preferably, the conductive layer 341 is provided so as to be embedded in the insulating layer 336. Furthermore, it is preferable that the upper surfaces of the conductive layer 341 and the insulating layer 336 are flattened.

[0433] The conductive layer 341 and the conductive layer 342 are bonded together, thereby electrically connecting the substrate 301A and the substrate 301B. By improving the flatness of the surface formed by the conductive layer 342 and the insulating layer 335, and the surface formed by the conductive layer 341 and the insulating layer 336, the bonding of the conductive layer 341 and the conductive layer 342 can be improved.

[0434] It is preferable to use the same conductive material for conductive layer 341 and conductive layer 342. For example, a metal film containing an element selected from Al, Cr, Cu, Ta, Ti, Mo, and W, or a metal nitride film (titanium nitride film, molybdenum nitride film, tungsten nitride film) composed of the above elements can be used. In particular, it is preferable to use copper for conductive layer 341 and conductive layer 342. This makes it possible to apply Cu-Cu (copper-copper) direct bonding technology (a technology that achieves electrical conductivity by connecting Cu (copper) pads to each other).

[0435] [Display device 100C] The display device 100C shown in Figure 25 has a configuration in which conductive layer 341 and conductive layer 342 are joined via bumps 347.

[0436] As shown in Figure 25, the conductive layer 341 and the conductive layer 342 can be electrically connected by providing a bump 347 between them. The bump 347 can be formed using a conductive material containing, for example, gold (Au), nickel (Ni), indium (In), or tin (Sn). Solder may also be used as the bump 347. An adhesive layer 348 may also be provided between the insulating layer 345 and the insulating layer 346. Furthermore, when the bump 347 is provided, the insulating layer 335 and the insulating layer 336 may be omitted.

[0437] [Display device 100D] The display device 100D shown in Figure 26 differs from the display device 100A mainly in its transistor configuration.

[0438] Transistor 320 is an OS transistor in which a metal oxide (also called an oxide semiconductor) is applied to the semiconductor layer where the channel is formed.

[0439] The transistor 320 has a semiconductor layer 321, an insulating layer 323, a conductive layer 324, a pair of conductive layers 325, an insulating layer 326, and a conductive layer 327.

[0440] Substrate 331 corresponds to substrate 291 in Figures 22A and 22B. An insulating substrate or a semiconductor substrate can be used as substrate 331.

[0441] An insulating layer 332 is provided on the substrate 331. The insulating layer 332 functions as a barrier layer that prevents impurities such as water or hydrogen from diffusing from the substrate 331 to the transistor 320, and prevents oxygen from detaching from the semiconductor layer 321 to the insulating layer 332. As the insulating layer 332, for example, a film that is less susceptible to hydrogen or oxygen diffusion than a silicon oxide film can be used, such as an aluminum oxide film, a hafnium oxide film, or a silicon nitride film.

[0442] A conductive layer 327 is provided on an insulating layer 332, and an insulating layer 326 is provided covering the conductive layer 327. The conductive layer 327 functions as the first gate electrode of the transistor 320, and a portion of the insulating layer 326 functions as the first gate insulating layer. It is preferable to use an oxide insulating film, such as a silicon oxide film, for at least the portion of the insulating layer 326 that is in contact with the semiconductor layer 321. It is preferable that the upper surface of the insulating layer 326 is flattened.

[0443] The semiconductor layer 321 is provided on the insulating layer 326. Preferably, the semiconductor layer 321 has a metal oxide film having semiconductor properties. A pair of conductive layers 325 are provided in contact with the semiconductor layer 321 and function as source electrodes and drain electrodes.

[0444] An insulating layer 328 is provided covering the top and side surfaces of a pair of conductive layers 325, as well as the side surfaces of the semiconductor layer 321, and an insulating layer 264 is provided on the insulating layer 328. The insulating layer 328 functions as a barrier layer to prevent impurities such as water or hydrogen from diffusing into the semiconductor layer 321 from the insulating layer 264, and to prevent oxygen from detaching from the semiconductor layer 321. An insulating film similar to that used for the insulating layer 332 can be used for the insulating layer 328.

[0445] An opening is provided in the insulating layer 328 and the insulating layer 264 that reaches the semiconductor layer 321. Inside this opening, the insulating layer 323 and the conductive layer 324 are embedded, in contact with the sides of the insulating layer 264, the insulating layer 328, and the conductive layer 325, as well as the upper surface of the semiconductor layer 321. The conductive layer 324 functions as a second gate electrode, and the insulating layer 323 functions as a second gate insulating layer.

[0446] The upper surfaces of the conductive layer 324, the insulating layer 323, and the insulating layer 264 are flattened so that their heights are the same or approximately the same, and the insulating layer 329 and insulating layer 265 are provided covering them.

[0447] Insulating layers 264 and 265 function as interlayer insulating layers. Insulating layer 329 functions as a barrier layer to prevent impurities such as water or hydrogen from diffusing from insulating layer 265 to transistor 320. As insulating layer 329, an insulating film similar to that used for insulating layers 328 and 332 can be used.

[0448] A plug 274, which is electrically connected to one of the pair of conductive layers 325, is provided so as to be embedded in the insulating layers 265, 329, 264, and 328. Here, it is preferable that the plug 274 has a conductive layer 274a that covers the sides of the openings of each of the insulating layers 265, 329, 264, and 328, and a part of the upper surface of the conductive layer 325, and a conductive layer 274b that is in contact with the upper surface of the conductive layer 274a. In this case, it is preferable to use a conductive material that does not easily allow hydrogen and oxygen to diffuse as the conductive layer 274a.

[0449] [Display device 100E] The display device 100E shown in Figure 27 has a configuration in which transistors 320A and 320B, each having an oxide semiconductor in the semiconductor on which the channel is formed, are stacked.

[0450] The configuration of transistors 320A and 320B, and their surrounding components, can be based on the display device 100D described above.

[0451] In this example, we have used a configuration in which two transistors having oxide semiconductors are stacked, but this is not the only option. For example, a configuration in which three or more transistors are stacked may also be used.

[0452] [Display device 100F] The display device 100F shown in Figure 28 has a configuration in which a transistor 310 with a channel formed on a substrate 301 and a transistor 320 containing a metal oxide in the semiconductor layer where the channel is formed are stacked.

[0453] An insulating layer 261 is provided covering the transistor 310, and a conductive layer 251 is provided on the insulating layer 261. An insulating layer 262 is provided covering the conductive layer 251, and a conductive layer 252 is provided on the insulating layer 262. The conductive layers 251 and 252 each function as wiring. An insulating layer 263 and an insulating layer 332 are provided covering the conductive layer 252, and a transistor 320 is provided on the insulating layer 332. An insulating layer 265 is provided covering the transistor 320, and a capacitor 240 is provided on the insulating layer 265. The capacitor 240 and the transistor 320 are electrically connected by a plug 274.

[0454] Transistor 320 can be used as a transistor constituting a pixel circuit. Transistor 310 can also be used as a transistor constituting a pixel circuit, or as a transistor constituting a drive circuit (scan line drive circuit and signal line drive circuit) for driving the pixel circuit. Furthermore, transistors 310 and 320 can be used as transistors constituting various circuits such as arithmetic circuits or memory circuits.

[0455] This configuration allows for the formation of not only pixel circuits but also, for example, driving circuits directly beneath the light-emitting elements, making it possible to miniaturize the display device compared to cases where the driving circuits are located around the display area.

[0456] [Display device 100G] Figure 29 shows a perspective view of the display device 100G, and Figure 30A shows a cross-sectional view of the display device 100G.

[0457] The display device 100G has a configuration in which substrate 152 and substrate 151 are bonded together. In Figure 29, substrate 152 is clearly indicated by a dashed line.

[0458] The display device 100G includes a pixel section 107, a connection section 140, a circuit 164, and wiring 165, etc. Figure 29 shows an example in which IC 173 and FPC 172 are mounted on the display device 100G. Therefore, the configuration shown in Figure 29 can also be called a display module having the display device 100G, an IC (integrated circuit), and an FPC. Here, a display module is defined as a display device with a connector such as an FPC attached to its substrate, or a substrate on which an IC is mounted.

[0459] The connection portion 140 is provided on the outside of the pixel portion 107. The connection portion 140 can be provided along one or more sides of the pixel portion 107. There may be one or more connection portions 140. Figure 29 shows an example in which the connection portion 140 is provided so as to surround all four sides of the pixel portion 107. At the connection portion 140, the common electrode of the light-emitting element and the conductive layer are electrically connected, and a potential can be supplied to the common electrode.

[0460] For example, a scan line drive circuit can be used as circuit 164.

[0461] The wiring 165 has the function of supplying signals and power to the pixel unit 107 and the circuit 164. These signals and power are input to the wiring 165 from an external source via the FPC 172 or from the IC 173.

[0462] Figure 29 shows an example in which IC 173 is provided on the substrate 151 using the COG (Chip On Glass) method or COF (Chip On Film) method, etc. IC 173 can be an IC having, for example, a scan line drive circuit or a signal line drive circuit. Note that the display device 100G and the display module may be configured without an IC. Alternatively, the IC may be mounted on an FPC, for example, using the COF method.

[0463] Figure 30A shows an example of a cross-section of the display device 100G when a portion of the area including the FPC 172, a portion of the circuit 164, a portion of the pixel portion 107, a portion of the connection portion 140, and a portion of the area including the end portion are cut.

[0464] The display device 100G shown in Figure 30A has a transistor 201, a transistor 205, a light-emitting element 130R that emits red light, a light-emitting element 130G that emits green light, and a light-emitting element 130B that emits blue light, etc., between substrates 151 and 152.

[0465] The light-emitting elements 130R, 130G, and 130B each have the stacked structure shown in Figure 2, except that they differ in the configuration of their pixel electrodes. For details of the light-emitting elements, please refer to Embodiment 1.

[0466] The light-emitting element 130R has a conductive layer 224R and a pixel electrode 111R on the conductive layer 224R. The light-emitting element 130G has a conductive layer 224G and a pixel electrode 111G on the conductive layer 224G. The light-emitting element 130B has a conductive layer 224B and a pixel electrode 111B on the conductive layer 224B. Note that not only the pixel electrode 111R, pixel electrode 111G, and pixel electrode 111B, but also the conductive layer 224R, conductive layer 224G, and conductive layer 224B can be called pixel electrodes.

[0467] The conductive layer 224R is connected to the conductive layer 222b of the transistor 205 through openings provided in the insulating layers 214, 215, and 213. The ends of the pixel electrodes 111R are located outside the ends of the conductive layer 224R.

[0468] The conductive layer 224G and pixel electrode 111G in the light-emitting element 130G, and the conductive layer 224B and pixel electrode 111B in the light-emitting element 130B are the same as the conductive layer 224R and pixel electrode 111R in the light-emitting element 130R, so a detailed explanation is omitted.

[0469] The conductive layer 224R, conductive layer 224G, and conductive layer 224B have recesses formed to cover the openings provided in the insulating layer 214. Layer 128 is embedded in these recesses.

[0470] Layer 128 has the function of flattening the recesses of conductive layers 224R, 224G, and 224B. Pixel electrodes 111R, 111G, and 111B, which are electrically connected to conductive layers 224R, 224G, and 224B, are provided on conductive layers 224R, 224G, 224B, and layer 128. Therefore, regions overlapping with the recesses of conductive layers 224R, 224G, and 224B can also be used as light-emitting regions, thereby increasing the aperture ratio of the pixels.

[0471] Layer 128 may be an insulating layer or a conductive layer. Various inorganic insulating materials, organic insulating materials, and conductive materials can be used for layer 128 as appropriate. In particular, it is preferable that layer 128 be formed using an insulating material, and especially preferable that it be formed using an organic insulating material. For example, an organic insulating material that can be used for the insulating layer 127 described above can be applied to layer 128.

[0472] A protective layer 131 is provided on the light-emitting elements 130R, 130G, and 130B. The protective layer 131 and the substrate 152 are bonded via an adhesive layer 142. A light-shielding layer 117 is provided on the substrate 152. A solid encapsulation structure or a hollow encapsulation structure can be applied to encapsulate the light-emitting elements 130. In Figure 30A, the space between the substrate 152 and the substrate 151 is filled with the adhesive layer 142, indicating a solid encapsulation structure. Alternatively, the space may be filled with an inert gas (such as nitrogen or argon), indicating a hollow encapsulation structure. In this case, the adhesive layer 142 may be provided so as not to overlap with the light-emitting elements. Furthermore, the space may be filled with a resin different from the adhesive layer 142, which is provided in a frame shape.

[0473] Figure 30A shows an example in which the connection portion 140 has a conductive layer 224C obtained by processing the same conductive film as conductive layers 224R, 224G, and 224B, and a conductive layer 123 obtained by processing the same conductive film as pixel electrodes 111R, 111G, and 111B.

[0474] The display device 100G is a top-emission type. The light emitted by the light-emitting element is emitted towards the substrate 152. It is preferable to use a material with high transmittance to visible light for the substrate 152. The pixel electrodes contain a material that reflects visible light, and the counter electrodes (common electrodes 115) contain a material that transmits visible light.

[0475] Both transistors 201 and 205 are formed on the substrate 151. These transistors can be manufactured using the same materials and the same process.

[0476] On the substrate 151, insulating layers 211, 213, 215, and 214 are provided in this order. A portion of insulating layer 211 functions as a gate insulating layer for each transistor. A portion of insulating layer 213 functions as a gate insulating layer for each transistor. Insulating layer 215 is provided covering the transistors. Insulating layer 214 is provided covering the transistors and functions as a planarization layer. The number of gate insulating layers and insulating layers covering the transistors are not limited and may be a single layer or two or more layers, respectively.

[0477] It is preferable to use a material that does not easily allow impurities such as water and hydrogen to diffuse into at least one layer of the insulating layer covering the transistor. This allows the insulating layer to function as a barrier layer. With such a configuration, the diffusion of impurities from the outside into the transistor can be effectively suppressed, thereby improving the reliability of the display device.

[0478] It is preferable to use inorganic insulating films for insulating layer 211, insulating layer 213, and insulating layer 215. Examples of inorganic insulating films that can be used include silicon nitride film, silicon oxynitride film, silicon oxide film, silicon nitride oxide film, aluminum oxide film, or aluminum nitride film. Alternatively, hafnium oxide film, yttrium oxide film, zirconium oxide film, gallium oxide film, tantalum oxide film, magnesium oxide film, lanthanum oxide film, cerium oxide film, and neodymium oxide film may also be used. Furthermore, two or more of the above insulating films may be laminated together.

[0479] An organic insulating layer is preferred for the insulating layer 214, which functions as a planarization layer. Materials that can be used for the organic insulating layer include acrylic resin, polyimide resin, epoxy resin, polyamide resin, polyimidoamide resin, siloxane resin, benzocyclobutene resin, phenol resin, and precursors of these resins. Alternatively, the insulating layer 214 may have a laminated structure of an organic insulating layer and an inorganic insulating layer. The outermost layer of the insulating layer 214 preferably functions as an etching protection layer. This suppresses the formation of recesses in the insulating layer 214 during processing of the conductive layer 224R or the pixel electrode 111R. Alternatively, as shown in Figure 30A, recesses may be provided in the insulating layer 214 during processing of the conductive layer 224R or the pixel electrode 111R.

[0480] Transistors 201 and 205 have a conductive layer 221 that functions as a gate, an insulating layer 211 that functions as a gate insulating layer, conductive layers 222a and 222b that function as source and drain, a semiconductor layer 231, an insulating layer 213 that functions as a gate insulating layer, and a conductive layer 223 that functions as a gate. Here, the same hatching pattern is applied to multiple layers obtained by processing the same conductive film. The insulating layer 211 is located between the conductive layer 221 and the semiconductor layer 231. The insulating layer 213 is located between the conductive layer 223 and the semiconductor layer 231.

[0481] The transistor structure of the display device of this embodiment is not particularly limited. For example, a planar transistor, a staggered transistor, or an inverse staggered transistor can be used. Furthermore, either a top-gate or bottom-gate transistor structure may be used. Alternatively, gates may be provided above and below the semiconductor layer in which the channel is formed.

[0482] Transistors 201 and 205 are configured in which a semiconductor layer on which a channel is formed is sandwiched between two gates. The transistors may be driven by connecting the two gates and supplying them with the same signal. Alternatively, the threshold voltage of the transistors may be controlled by applying a potential to control the threshold voltage to one of the two gates and a potential to drive the other gate.

[0483] The crystallinity of the semiconductor material used in the transistor is not particularly limited; amorphous semiconductors, crystalline semiconductors (microcrystalline semiconductors, polycrystalline semiconductors, single-crystal semiconductors, or semiconductors having a crystalline region in part) may be used. Using a crystalline semiconductor is preferable because it can suppress the degradation of transistor characteristics.

[0484] The semiconductor layer of the transistor preferably has a metal oxide. In other words, the display device of this embodiment preferably uses a transistor (hereinafter referred to as an OS transistor) that uses a metal oxide in the channel formation region.

[0485] Examples of crystalline oxide semiconductors include CAAC (c-axis-aligned crystalline)-OS and nc (nanocrystalline)-OS.

[0486] Alternatively, a transistor using silicon as the channel-forming region (Si transistor) may be used. Examples of silicon include single-crystal silicon, polycrystalline silicon, or amorphous silicon. In particular, a transistor having low-temperature polysilicon (LTPS (Low Temperature Poly Silicon)) in the semiconductor layer (hereinafter also referred to as an LTPS transistor) can be used. LTPS transistors have high field-effect mobility and good frequency characteristics.

[0487] By using Si transistors such as LTPS transistors, circuits that need to be driven at high frequencies (e.g., source driver circuits) can be fabricated on the same board as the display unit. This simplifies the external circuits implemented in the display device, reducing component and mounting costs.

[0488] OS transistors have extremely high field-effect mobility compared to transistors using amorphous silicon. Furthermore, OS transistors exhibit remarkably low source-drain leakage current (hereinafter also referred to as off-current) in the off state, allowing them to retain charge stored in a capacitor connected in series with the transistor for extended periods. Additionally, the application of OS transistors can reduce the power consumption of display devices.

[0489] Furthermore, to increase the luminescence brightness of the light-emitting elements included in the pixel circuit, it is necessary to increase the amount of current flowing through the light-emitting elements. To achieve this, it is necessary to increase the source-drain voltage of the drive transistor included in the pixel circuit. Compared to Si transistors, OS transistors have a higher breakdown voltage between the source and drain, so a higher voltage can be applied between the source and drain of an OS transistor. Therefore, by using an OS transistor as the drive transistor included in the pixel circuit, the amount of current flowing through the light-emitting elements can be increased, thereby increasing the luminescence brightness of the light-emitting elements.

[0490] Furthermore, when the transistor operates in the saturation region, OS transistors exhibit smaller changes in source-drain current in response to changes in gate-source voltage compared to Si transistors. Therefore, by using OS transistors as driving transistors in the pixel circuit, the current flowing between the source and drain can be precisely controlled by changes in gate-source voltage, thereby controlling the amount of current flowing to the light-emitting element. This allows for a wider range of tonal gradations in the pixel circuit.

[0491] Furthermore, in terms of the saturation characteristics of the current flowing when a transistor operates in the saturation region, OS transistors can supply a more stable current (saturation current) than Si transistors, even when the source-drain voltage gradually increases. For this reason, by using OS transistors as driving transistors, a stable current can be supplied to the light-emitting element even if there are variations in the current-voltage characteristics of the organic EL element. In other words, when operating in the saturation region, the source-drain current remains almost unchanged even when the source-drain voltage is increased, thus stabilizing the luminescence brightness of the light-emitting element.

[0492] As described above, by using OS transistors in the drive transistors included in the pixel circuit, it is possible to achieve "suppression of black level floating," "increase in luminous brightness," "multi-gradation," and "suppression of variations in the characteristics of light-emitting elements."

[0493] The semiconductor layer preferably comprises, for example, indium, M (where M is one or more selected from gallium, aluminum, silicon, boron, yttrium, tin, copper, vanadium, beryllium, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, and magnesium), and zinc. In particular, it is preferable that M is one or more selected from aluminum, gallium, yttrium, and tin.

[0494] In particular, it is preferable to use an oxide containing indium (In), gallium (Ga), and zinc (Zn) (also written as IGZO) as the semiconductor layer. Alternatively, it is preferable to use an oxide containing indium, tin, and zinc. Alternatively, it is preferable to use an oxide containing indium, gallium, tin, and zinc. Alternatively, it is preferable to use an oxide containing indium (In), aluminum (Al), and zinc (Zn) (also written as IAZO). Alternatively, it is preferable to use an oxide containing indium (In), aluminum (Al), gallium (Ga), and zinc (Zn) (also written as IAGZO).

[0495] When the semiconductor layer is an In-M-Zn oxide, it is preferable that the atomic ratio of In in the In-M-Zn oxide is equal to or greater than the atomic ratio of M. Examples of atomic ratios of metal elements in such In-M-Zn oxides include compositions where In:M:Zn=1:1:1 or close to it, In:M:Zn=1:1:1.2 or close to it, In:M:Zn=2:1:3 or close to it, In:M:Zn=3:1:2 or close to it, In:M:Zn=4:2:3 or close to it, In:M:Zn=4:2:4.1 or close to it, In:M:Zn=5:1:3 or close to it, In:M:Zn=5:1:6 or close to it, In:M:Zn=5:1:7 or close to it, In:M:Zn=5:1:8 or close to it, In:M:Zn=6:1:6 or close to it, In:M:Zn=5:2:5 or close to it, and so on. Note that "nearby composition" includes a range of ±30% of the desired atomic ratio.

[0496] For example, when describing an atomic ratio of In:Ga:Zn = 4:2:3 or a composition close to that, it includes cases where, when the atomic ratio of In is 4, the atomic ratio of Ga is between 1 and 3, and the atomic ratio of Zn is between 2 and 4. Also, when describing an atomic ratio of In:Ga:Zn = 5:1:6 or a composition close to that, it includes cases where, when the atomic ratio of In is 5, the atomic ratio of Ga is greater than 0.1 and 2 or less, and the atomic ratio of Zn is between 5 and 7. Furthermore, when describing an atomic ratio of In:Ga:Zn = 1:1:1 or a composition close to that, it includes cases where, when the atomic ratio of In is 1, the atomic ratio of Ga is greater than 0.1 and 2 or less, and the atomic ratio of Zn is greater than 0.1 and 2 or less.

[0497] The transistors in circuit 164 and the transistors in pixel unit 107 may have the same structure or different structures. The structures of the multiple transistors in circuit 164 may all be the same or there may be two or more different structures. Similarly, the structures of the multiple transistors in pixel unit 107 may all be the same or there may be two or more different structures.

[0498] All of the transistors in the pixel unit 107 may be OS transistors, all of the transistors in the pixel unit 107 may be Si transistors, or some of the transistors in the pixel unit 107 may be OS transistors and the rest may be Si transistors.

[0499] For example, by using both LTPS transistors and OS transistors in the pixel section 107, a display device with low power consumption and high driving capability can be realized. Furthermore, a configuration combining LTPS transistors and OS transistors is sometimes referred to as LTPO. It is preferable, for example, to use an OS transistor as a switch to control the conduction and non-conductivity of wiring, and an LTPS transistor as a transistor to control current.

[0500] For example, one of the transistors in the pixel unit 107 functions as a transistor for controlling the current flowing to the light-emitting element and can be called a drive transistor. One of the source and drain of the drive transistor is electrically connected to the pixel electrode of the light-emitting element. It is preferable to use an LTPS transistor for this drive transistor. This makes it possible to increase the current flowing to the light-emitting element in the pixel circuit.

[0501] On the other hand, the other transistor in the pixel unit 107 functions as a switch for controlling the selection and deselection of pixels, and can also be called a selection transistor. The gate of the selection transistor is electrically connected to the gate line, and one of the source and drain is electrically connected to the signal line. It is preferable to use an OS transistor for the selection transistor. This makes it possible to maintain the gradation of pixels even when the frame frequency is significantly reduced (e.g., 1 fps or less), and thus power consumption can be reduced by stopping the driver when displaying still images.

[0502] Thus, a display device according to one aspect of the present invention can combine a high aperture ratio, high resolution, high display quality, and low power consumption.

[0503] Furthermore, one embodiment of the present invention is a display device having an OS transistor and an MML (metal maskless) structure light-emitting element. This configuration makes it possible to extremely low leakage current that can flow through the transistor and leakage current that can flow between adjacent light-emitting elements (sometimes referred to as lateral leakage current, transverse leakage current, or lateral leakage current). With this configuration, when an image is displayed on the display device, the observer can observe one or more of the following: image sharpness, image clarity, high saturation, and high contrast ratio. Moreover, by having an extremely low leakage current that can flow through the transistor and transverse leakage current between light-emitting elements, it is possible to achieve a display with as little light leakage (so-called black floating) that may occur when displaying black as possible.

[0504] In particular, even among light-emitting elements with an MML structure, applying the SBS structure described above results in a configuration where the layers between the light-emitting elements are separated, thereby eliminating or significantly reducing lateral leakage current.

[0505] Figures 30B and 30C show other examples of transistor configurations.

[0506] Transistors 209 and 210 each have a conductive layer 221 that functions as a gate, an insulating layer 211 that functions as a gate insulating layer, a semiconductor layer 231 having a channel forming region 231i and a pair of low-resistance regions 231n, a conductive layer 222a connected to one of the pair of low-resistance regions 231n, a conductive layer 222b connected to the other of the pair of low-resistance regions 231n, an insulating layer 225 that functions as a gate insulating layer, a conductive layer 223 that functions as a gate, and an insulating layer 215 covering the conductive layer 223. The insulating layer 211 is located between the conductive layer 221 and the channel forming region 231i. The insulating layer 225 is located at least between the conductive layer 223 and the channel forming region 231i. Furthermore, an insulating layer 218 covering the transistor may be provided.

[0507] In the transistor 209 shown in Figure 30B, an example is shown where the insulating layer 225 covers the top and sides of the semiconductor layer 231. The conductive layers 222a and 222b are connected to the low-resistance region 231n through openings provided in the insulating layers 225 and 215, respectively. Of the conductive layers 222a and 222b, one functions as the source and the other as the drain.

[0508] On the other hand, in the transistor 210 shown in Figure 30C, the insulating layer 225 overlaps with the channel formation region 231i of the semiconductor layer 231, but does not overlap with the low-resistance region 231n. For example, the structure shown in Figure 30C can be fabricated by processing the insulating layer 225 using the conductive layer 223 as a mask. In Figure 30C, an insulating layer 215 is provided covering the insulating layer 225 and the conductive layer 223, and the conductive layer 222a and conductive layer 222b are connected to the low-resistance region 231n, respectively, through openings in the insulating layer 215.

[0509] A connection portion 204 is provided in the region of substrate 151 where substrate 152 does not overlap. At the connection portion 204, wiring 165 is electrically connected to FPC 172 via conductive layer 166 and connection layer 242. The conductive layer 166 is shown as an example of a laminated structure consisting of a conductive film obtained by processing the same conductive film as conductive layers 224R, 224G, and 224B, and a conductive film obtained by processing the same conductive film as pixel electrodes 111R, 111G, and 111B. On the upper surface of the connection portion 204, the conductive layer 166 is exposed. This allows the connection portion 204 and FPC 172 to be electrically connected via the connection layer 242.

[0510] It is preferable to provide a light-shielding layer 117 on the surface of the substrate 152 that faces the substrate 151. The light-shielding layer 117 can be provided between adjacent light-emitting elements, at connection points 140, and at circuits 164, etc. In addition, various optical components can be arranged on the outside of the substrate 152.

[0511] Materials that can be used for substrate 120 can be applied to substrate 151 and substrate 152, respectively.

[0512] As the adhesive layer 142, a material that can be used for the resin layer 122 can be applied.

[0513] As the connecting layer 242, an anisotropic conductive film (ACF) or an anisotropic conductive paste (ACP) can be used.

[0514] [Display device 100H] The display device 100H shown in Figure 31A is a modified version of the display device 100G shown in Figure 30A, and differs from the display device 100G mainly in that it is a bottom-emission type display device.

[0515] Light emitted from the light-emitting element 130 is emitted towards the substrate 151. It is preferable to use a material with high transmittance to visible light for the substrate 151. On the other hand, the light transmittance of the material used for the substrate 152 is not a requirement.

[0516] It is preferable to provide a light-shielding layer 117 between the substrate 151 and the transistor 201, and between the substrate 151 and the transistor 205. Figure 31A shows an example in which a light-shielding layer 117 is provided on the substrate 151, an insulating layer 153 is provided on the light-shielding layer 117, and transistors 201 and 205 are provided on the insulating layer 153.

[0517] The conductive layer 224R, conductive layer 224G, conductive layer 224B, pixel electrode 111R, pixel electrode 111G, and pixel electrode 111B are each made of a material with high transmittance to visible light. On the other hand, it is preferable to use a material that reflects visible light for the common electrode 115.

[0518] Figures 30A and 31A show an example where the upper surface of layer 128 has a flat portion, but the shape of layer 128 is not particularly limited. Figures 31B to 31D show modified examples of layer 128.

[0519] As shown in Figures 31B and 31D, the upper surface of layer 128 can be configured to have a shape in which the center and its vicinity are recessed in a cross-sectional view, that is, a shape having a concave curved surface.

[0520] Furthermore, as shown in Figure 31C, the upper surface of layer 128 can be configured to have a shape that bulges in the center and its vicinity in a cross-sectional view, that is, a shape with a convex curved surface.

[0521] Furthermore, the upper surface of layer 128 may have one or both of a convex and a concave surface. Also, the number of convex and concave surfaces on the upper surface of layer 128 is not limited and can be one or more.

[0522] Furthermore, the height of the top surface of layer 128 and the height of the top surface of, for example, the conductive layer 224R may be the same or approximately the same, or they may be different from each other. For example, the height of the top surface of layer 128 may be lower or higher than the height of the top surface of the conductive layer 224R.

[0523] Furthermore, Figure 31B can be seen as an example in which layer 128 is housed inside a recess formed in the conductive layer 224R. On the other hand, as shown in Figure 31D, layer 128 may exist outside the recess formed in the conductive layer 224R, that is, the width of the upper surface of layer 128 may be wider than that of the recess.

[0524] [Display device 100I] The display device 100I shown in Figure 32 is a modified version of the display device 100G shown in Figure 30A, and differs from the display device 100G mainly in that it has a colored layer 132R, a colored layer 132G, and a colored layer 132B.

[0525] In the display device 100I, the light-emitting element 130 has a region that overlaps with one of the colored layers 132R, 132G, and 132B. The colored layers 132R, 132G, and 132B can be provided on the substrate 151 side of the substrate 152. The edges of the colored layer 132R, the edges of the colored layer 132G, and the edges of the colored layer 132B can overlap with the light-shielding layer 117. For details of the configuration of the light-emitting element 130 in the display device 100I, for example, refer to Figure 8A.

[0526] In the display device 100I, the light-emitting element 130 can emit, for example, white light. Furthermore, for example, the colored layer 132R can transmit red light, the colored layer 132G can transmit green light, and the colored layer 132B can transmit blue light. The display device 100I may also be configured with the colored layers 132R, 132G, and 132B placed between the protective layer 131 and the adhesive layer 142. In this case, the protective layer 131 is preferably flattened as shown in Figure 8A.

[0527] [Display device 100J] The display device 100J shown in Figure 33 is a modified version of the display device 100I shown in Figure 32, and differs from the display device 100I mainly in that it is a bottom-emission type display device.

[0528] The light emitted by the light-emitting element 130 is emitted towards the substrate 151, similar to the display device 100H shown in Figure 31A. It is preferable to use a material with high transmittance to visible light for the substrate 151. On the other hand, the light transmittance of the material used for the substrate 152 is not a requirement.

[0529] The colored layer 132 is provided between the light-emitting element 130 and the substrate 151. Figure 33 shows an example in which the colored layer 132R, colored layer 132G, and colored layer 132B are provided between the insulating layer 215 and the insulating layer 214.

[0530] Furthermore, similar to the display device 100H shown in Figure 31A, it is preferable to provide a light-shielding layer 117 between the substrate 151 and the transistor 201, and between the substrate 151 and the transistor 205. Figure 33 shows an example in which a light-shielding layer 117 is provided on the substrate 151, an insulating layer 153 is provided on the light-shielding layer 117, and transistors 201 and 205 are provided on the insulating layer 153.

[0531] Furthermore, similar to the display device 100H shown in Figure 31A, the conductive layer 224R, conductive layer 224G, conductive layer 224B, pixel electrode 111R, pixel electrode 111G, and pixel electrode 111B are each made of a material with high transmittance to visible light. On the other hand, it is preferable to use a material that reflects visible light for the common electrode 115.

[0532] This embodiment can be combined with other embodiments as appropriate. Furthermore, if multiple configuration examples are shown within a single embodiment in this specification, these configuration examples can be combined as appropriate.

[0533] (Embodiment 4) This embodiment describes a light-emitting element that can be used in a display device according to one aspect of the present invention.

[0534] As shown in Figure 34A, the light-emitting element has an EL layer 763 between a pair of electrodes (lower electrode 761 and upper electrode 762). The EL layer 763 can be composed of multiple layers, such as layer 780, light-emitting layer 771, and layer 790.

[0535] The light-emitting layer 771 has at least a light-emitting material.

[0536] When the lower electrode 761 is the anode and the upper electrode 762 is the cathode, layer 780 has one or more of the following: a layer containing a material with high hole injection properties (hole injection layer), a layer containing a material with high hole transport properties (hole transport layer), and a layer containing a material with high electron blocking properties (electron blocking layer). Similarly, layer 790 has one or more of the following: a layer containing a material with high electron injection properties (electron injection layer), a layer containing a material with high electron transport properties (electron transport layer), and a layer containing a material with high hole blocking properties (hole blocking layer). When the lower electrode 761 is the cathode and the upper electrode 762 is the anode, layers 780 and 790 have the opposite configurations to those described above.

[0537] A configuration having a layer 780, an emissive layer 771, and a layer 790 provided between a pair of electrodes can function as a single emissive unit, and in this specification, the configuration shown in Figure 34A is referred to as a single structure.

[0538] Furthermore, Figure 34B shows a modified example of the EL layer 763 of the light-emitting element shown in Figure 34A. Specifically, the light-emitting element shown in Figure 34B has a layer 781 on the lower electrode 761, a layer 782 on the layer 781, a light-emitting layer 771 on the layer 782, a layer 791 on the light-emitting layer 771, a layer 792 on the layer 791, and an upper electrode 762 on the layer 792.

[0539] When the lower electrode 761 is the anode and the upper electrode 762 is the cathode, for example, layer 781 can be a hole injection layer, layer 782 a hole transport layer, layer 791 an electron transport layer, and layer 792 an electron injection layer. Also, when the lower electrode 761 is the cathode and the upper electrode 762 is the anode, layer 781 can be an electron injection layer, layer 782 an electron transport layer, layer 791 a hole transport layer, and layer 792 a hole injection layer. By using such a layer structure, carriers can be efficiently injected into the light-emitting layer 771, and the efficiency of carrier recombination within the light-emitting layer 771 can be increased.

[0540] Furthermore, as shown in Figures 34C and 34D, a configuration in which multiple light-emitting layers (light-emitting layers 771, 772, and 773) are provided between layer 780 and layer 790 is also a variation of the single structure.

[0541] Furthermore, as shown in Figures 34E and 34F, a configuration in which multiple light-emitting units (EL layers 763a and EL layers 763b) are connected in series via a charge generation layer 785 is referred to as a tandem structure in this specification. The tandem structure may also be called a stacked structure. By using a tandem structure, a light-emitting element capable of high-brightness emission can be achieved.

[0542] In Figures 34C and 34D, the light-emitting layers 771, 772, and 773 may be made of light-emitting materials that emit light of the same color, or even the same light-emitting material may be used. For example, light-emitting materials that emit blue light may be used for the light-emitting layers 771, 772, and 773. A color conversion layer may be provided as layer 764 as shown in Figure 34D.

[0543] Furthermore, light-emitting materials that emit light of different colors may be used for the light-emitting layers 771, 772, and 773, respectively. If the light emitted by the light-emitting layers 771, 772, and 773 are complementary colors, white light emission can be obtained. A color filter (also called a colored layer) may be provided as layer 764 as shown in Figure 34D. By passing white light through the color filter, light of a desired color can be obtained.

[0544] A light-emitting element that emits white light preferably has two or more light-emitting layers. For example, when obtaining white light emission using two light-emitting layers, the light-emitting layers should be selected such that the light-emitting colors of each layer are complementary colors. For example, by making the light-emitting color of the first light-emitting layer and the light-emitting color of the second light-emitting layer complementary colors, a configuration that emits white light as a whole can be obtained. Also, when obtaining white light emission using three or more light-emitting layers, the light-emitting elements can be configured so that the light-emitting elements as a whole emit white light when the light-emitting colors of each of the three or more layers combine.

[0545] Furthermore, in Figures 34E and 34F, the light-emitting layer 771 and the light-emitting layer 772 may be made of light-emitting materials that emit light of the same color, or even the same light-emitting material. Alternatively, the light-emitting layer 771 and the light-emitting layer 772 may be made of light-emitting materials that emit light of different colors. When the light emitted by the light-emitting layer 771 and the light emitted by the light-emitting layer 772 are complementary colors, white light emission is obtained. Figure 34F shows an example in which a further layer 764 is provided. As layer 764, one or both of a color conversion layer and a color filter (coloring layer) can be used.

[0546] Furthermore, in Figures 34C, 34D, 34E, and 34F, as shown in Figure 34B, layer 780 and layer 790 may each be independently constructed as a laminated structure consisting of two or more layers.

[0547] Next, we will describe the materials that can be used in light-emitting devices.

[0548] Of the lower electrode 761 and upper electrode 762, the electrode that extracts light preferably uses a conductive film that transmits visible light. Furthermore, it is preferable to use a conductive film that reflects visible light on the electrode that does not extract light. In addition, if the display device has a light-emitting element that emits infrared light, it is preferable to use a conductive film that transmits both visible light and infrared light on the electrode that extracts light, and a conductive film that reflects both visible light and infrared light on the electrode that does not extract light.

[0549] Furthermore, a conductive film that transmits visible light may also be used on the electrode that does not extract light. In this case, it is preferable to place the electrode between the reflective layer and the EL layer 763. In other words, the light emitted from the EL layer 763 may be reflected by the reflective layer and extracted from the display device.

[0550] As materials for forming the pair of electrodes of a light-emitting element, metals, alloys, electrically conductive compounds, and mixtures thereof can be used as appropriate. Specifically, examples include indium tin oxide (In-Sn oxide, also called ITO), In-Si-Sn oxide (also called ITSO), indium zinc oxide (In-Zn oxide), In-W-Zn oxide, aluminum-containing alloys such as aluminum, nickel, and lanthanum alloys (Al-Ni-La), as well as silver-containing alloys such as silver-magnesium alloys and silver-palladium-copper alloys (Ag-Pd-Cu, also written as APC). In addition, metals such as aluminum (Al), magnesium, 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), or neodymium (Nd), or alloys containing these in appropriate combinations, can also be used. Furthermore, elements belonging to Group 1 or Group 2 of the periodic table not exemplified above (for example, lithium (Li), cesium (Cs), calcium (Ca), strontium (Sr)), rare earth metals such as europium (Eu), ytterbium (Yb), and alloys containing these in appropriate combinations, graphene, etc., can also be used.

[0551] It is preferable that the light-emitting element has a microcavity structure. Therefore, it is preferable that one of the pair of electrodes in the light-emitting element has an electrode that is both transparent and reflective to visible light (a semi-transmissive / semi-reflective electrode), and the other electrode has an electrode that is reflective to visible light (a reflective electrode). By having a microcavity structure in the light-emitting element, the light emitted from the light-emitting layer can be resonated between the two electrodes, thereby strengthening the light emitted from the light-emitting element.

[0552] The light transmittance of the transparent electrode shall be 40% or more. For example, it is preferable to use an electrode with a visible light transmittance (light with a wavelength of 400 nm or more and less than 750 nm) of 40% or more in the light-emitting element. The visible light reflectance of the semi-transparent / semi-reflective electrode shall be 10% or more and 95% or less, preferably 30% or more and 80% or less. The visible light reflectance of the reflective electrode shall be 40% or more and 100% or less, preferably 70% or more and 100% or less. The resistivity of these electrodes shall be 1 × 10⁻⁶ -2 A value of Ωcm or less is preferable.

[0553] The light-emitting element may use either low-molecular-weight compounds or high-molecular-weight compounds, and may also contain inorganic compounds. The layers constituting the light-emitting element can be formed by methods such as vapor deposition (including vacuum deposition), transfer, printing, inkjet, or coating.

[0554] The light-emitting layer may have one or more types of light-emitting materials. The light-emitting materials may include those exhibiting colors such as blue, purple, blue-violet, green, yellow-green, yellow, orange, or red. Furthermore, materials emitting near-infrared light may also be used as light-emitting materials.

[0555] Examples of luminescent materials include fluorescent materials, phosphorescent materials, TADF materials, and quantum dot materials.

[0556] 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.

[0557] Examples of phosphorescent materials include organometallic complexes (especially iridium complexes) having a 4H-triazole skeleton, 1H-triazole skeleton, imidazole skeleton, pyrimidine skeleton, pyrazine skeleton, or pyridine skeleton; organometallic complexes (especially iridium complexes) using phenylpyridine derivatives having electron-withdrawing groups as ligands; platinum complexes; and rare earth metal complexes.

[0558] The light-emitting layer may contain one or more types of organic compounds (host material, assist material, etc.) in addition to the light-emitting substance (guest material). The one or more types of organic compounds may include one or both of materials with high hole transport properties (hole transport material) and materials with high electron transport properties (electron transport material). Furthermore, bipolar materials or TADF materials may be used as the one or more types of organic compounds.

[0559] The light-emitting layer preferably comprises, for example, a phosphorescent material and a combination of a hole-transporting material and an electron-transporting material that readily forms an excitation complex. This configuration allows for efficient emission using ExTET (Exciplex-Triplet Energy Transfer), which is energy transfer from the excitation complex to the light-emitting material (phosphorescent material). By selecting a combination that forms an excitation complex that exhibits emission overlapping with the wavelength of the lowest-energy absorption band of the light-emitting material, energy transfer becomes smoother, and light emission can be obtained efficiently. This configuration simultaneously achieves high efficiency, low-voltage operation, and a long lifespan for the light-emitting element.

[0560] The EL layer 763 may further include layers other than the light-emitting layer, such as a material with high hole injection properties, a material with high hole transport properties, a hole blocking material, a material with high electron transport properties, a material with high electron injection properties, an electron blocking material, or a bipolar material (a material with high electron transport and hole transport properties).

[0561] The hole injection layer is a layer that injects holes from the anode into the hole transport layer, and is a layer containing a material with high hole injection capabilities. Examples of materials with high hole injection capabilities include aromatic amine compounds and composite materials containing hole transport materials and acceptor materials (electron-accepting materials).

[0562] As the hole-transporting material, a material with high hole-transporting properties that can be used in the hole-transporting layer, as described later, can be used.

[0563] As acceptor materials, for example, oxides of metals belonging to groups 4 to 8 of the periodic table can be used. Specifically, these include molybdenum oxide, vanadium oxide, niobium oxide, tantalum oxide, chromium oxide, tungsten oxide, manganese oxide, and rhenium oxide. Among these, molybdenum oxide is particularly preferred because it is stable in the atmosphere, has low hygroscopicity, and is easy to handle. Organic acceptor materials containing fluorine can also be used. Organic acceptor materials such as quinodimethane derivatives, chloranil derivatives, and hexaazatriphenylene derivatives can also be used. Furthermore, as a material with high hole injection capabilities, a mixed material may be used, which is a mixture of the above-mentioned oxides of metals belonging to groups 4 to 8 of the periodic table (typically molybdenum oxide) and an organic material.

[0564] The hole transport layer is a layer that transports holes injected from the anode by the hole injection layer to the light-emitting layer. The hole transport layer is a layer containing a hole-transporting material. The hole-transporting material is 1 × 10⁻¹⁶ -6 cm 2 Materials having a hole mobility of / Vs or higher are preferred. However, other materials can also be used as long as they have higher hole transport capabilities than electron transport. Preferred hole transport materials include π-electron-rich heteroaromatic compounds (e.g., carbazole derivatives, thiophene derivatives, or furan derivatives), aromatic amines (compounds having an aromatic amine skeleton), and other materials with high hole transport capabilities.

[0565] The electron blocking layer is provided adjacent to the light-emitting layer. The electron blocking layer is a layer containing a material having hole transporting properties and capable of blocking electrons. Among the above hole transporting materials, a material having electron blocking properties can be used for the electron blocking layer.

[0566] Since the electron blocking layer has hole transporting properties, it can also be called a hole transporting layer. Also, among the hole transporting layers, a layer having electron blocking properties can be called an electron blocking layer.

[0567] The electron transport layer is a layer that transports electrons injected from the cathode to the light-emitting layer by the electron injection layer. The electron transport layer is a layer containing an electron transporting material. As the electron transporting material, a substance having an electron mobility of 1×10 -6 cm 2 / Vs or more is preferable. In addition, as long as it is a substance with higher electron transportability than holes, other materials can also be used. As the electron transporting material, in addition to metal complexes having a quinoline skeleton, metal complexes having a benzoquinoline skeleton, metal complexes having an oxazole skeleton, or metal complexes having a thiazole skeleton, etc., oxadiazole derivatives, triazole derivatives, imidazole derivatives, oxazole derivatives, thiazole derivatives, phenanthroline derivatives, quinoline derivatives having a quinoline ligand, benzoquinoline derivatives, quinoxaline derivatives, dibenzoquinoxaline derivatives, pyridine derivatives, bipyridine derivatives, pyrimidine derivatives, or other electron transporting materials such as π-electron deficient heteroaromatic compounds containing nitrogen-containing heteroaromatic compounds can be used.

[0568] The hole blocking layer is provided adjacent to the light-emitting layer. The hole blocking layer is a layer containing a material having electron transporting properties and capable of blocking holes. Among the above electron transporting materials, a material having hole blocking properties can be used for the hole blocking layer.

[0569] Since the hole blocking layer has electron transporting properties, it can also be called an electron transport layer. Also, among the electron transport layers, a layer having hole blocking properties can be called a hole blocking layer.

[0570] The electron injection layer is a layer that injects electrons from the cathode to the electron transport layer, and is a layer containing a material with high electron injection capabilities. Alkali metals, alkaline earth metals, or compounds thereof can be used as materials with high electron injection capabilities. Composite materials containing both electron transport materials and donor materials (electron-donating materials) can also be used as materials with high electron injection capabilities.

[0571] Furthermore, it is preferable that the LUMO level of a material with high electron injection capacity has a small difference (specifically, 0.5 eV or less) from the work function value of the material used as the cathode.

[0572] The electron injection layer contains, for example, lithium, cesium, ytterbium, lithium fluoride (LiF), cesium fluoride (CsF), and calcium fluoride (CaF). x (where X is any number), 8-(quinolinolato)lithium (abbreviation: Liq), 2-(2-pyridyl)phenolatrium (abbreviation: LiPP), 2-(2-pyridyl)-3-pyridinolatrium (abbreviation: LiPPy), 4-phenyl-2-(2-pyridyl)phenolatrium (abbreviation: LiPPP), lithium oxide (LiO x Alternatively, alkali metals such as cesium carbonate, alkaline earth metals, or compounds thereof can be used. Furthermore, the electron injection layer may have a layered structure of two or more layers. For example, such a layered structure may consist of lithium fluoride as the first layer and ytterbium as the second layer.

[0573] The electron injection layer may contain an electron-transporting material. For example, a compound having a lone pair of electrons and an electron-deficient heteroaromatic ring can be used as the electron-transporting material. Specifically, a compound having at least one of a pyridine ring, a diazine ring (pyrimidine ring, pyrazine ring, pyridazine ring), or a triazine ring can be used.

[0574] Furthermore, the lowest unoccupied molecular orbital (LUMO) level of organic compounds containing lone pairs of electrons is preferably between -3.6 eV and -2.3 eV. In general, the highest occupied molecular orbital (HOMO) level and LUMO level of organic compounds can be estimated by methods such as cyclic voltammetry (CV), photoelectron spectroscopy, optical absorption spectroscopy, or inverse photoelectron spectroscopy.

[0575] For example, 4,7-diphenyl-1,10-phenanthroline (abbreviated as BPhen), 2,9-di(naphthalene-2-yl)-4,7-diphenyl-1,10-phenanthroline (abbreviated as NBPhen), diquinoxalino[2,3-a:2',3'-c]phenazine (abbreviated as HATNA), or 2,4,6-tris[3'-(pyridine-3-yl)biphenyl-3-yl]-1,3,5-triazine (abbreviated as TmPPPyTz) can be used in organic compounds containing lone pairs of electrons. NBPhen has a higher glass transition temperature (Tg) and superior heat resistance compared to BPhen.

[0576] Furthermore, when fabricating a tandem-structured light-emitting device, a charge generation layer (also called an intermediate layer) is provided between the two light-emitting units. The intermediate layer has the function of injecting electrons into one of the two light-emitting units and holes into the other when a voltage is applied between the pair of electrodes.

[0577] As the charge generation layer, for example, a material applicable to the electron injection layer, such as lithium, can be suitably used. Alternatively, as the charge generation layer, a material applicable to the hole injection layer can be suitably used. Furthermore, the charge generation layer can include a layer containing a hole transport material and an acceptor material (electron-accepting material). Alternatively, the charge generation layer can include a layer containing an electron transport material and a donor material. By forming such a charge generation layer, the increase in driving voltage when light-emitting units are stacked can be suppressed.

[0578] This embodiment can be combined with other embodiments as appropriate. Furthermore, if multiple configuration examples are shown within a single embodiment in this specification, these configuration examples can be combined as appropriate.

[0579] (Embodiment 5) This embodiment describes an electronic device according to one aspect of the present invention.

[0580] The electronic device of this embodiment has a display device according to one aspect of the present invention in its display unit. The display device according to one aspect of the present invention is highly reliable and can be easily made high-definition and high-resolution. Therefore, it can be used in the display units of various electronic devices.

[0581] Examples of electronic devices include television sets, desktop or notebook personal computers, computer monitors, digital signage, large game machines such as pachinko machines, and other electronic devices with relatively large screens, as well as digital cameras, digital video cameras, digital photo frames, mobile phones, portable game consoles, personal digital assistants, and audio playback devices.

[0582] In particular, a display device according to one aspect of the present invention can be used suitably in electronic devices having a relatively small display area because it can increase the resolution. Examples of such electronic devices include wristwatch-type and bracelet-type information terminals (wearable devices), as well as wearable devices that can be worn on the head, such as VR devices such as head-mounted displays, AR devices such as glasses, and MR devices.

[0583] A display device according to one aspect of the present invention preferably has an extremely high resolution such as HD (1280 x 720 pixels), FHD (1920 x 1080 pixels), WQHD (2560 x 1440 pixels), WQXGA (2560 x 1600 pixels), 4K (3840 x 2160 pixels), or 8K (7680 x 4320 pixels). In particular, a resolution of 4K, 8K, or higher is preferred. Furthermore, the pixel density (resolution) of the display device according to one aspect of the present invention is preferably 100 ppi or more, preferably 300 ppi or more, more preferably 500 ppi or more, more preferably 1000 ppi or more, more preferably 2000 ppi or more, more preferably 3000 ppi or more, more preferably 5000 ppi or more, and even more preferably 7000 ppi or more. By using a display device having either high resolution or high detail, or both, it becomes possible to further enhance the sense of presence and depth in personal electronic devices such as portable or home-use devices. Furthermore, there are no particular limitations on the screen ratio (aspect ratio) of the display device according to one embodiment of the present invention. For example, the display device can support various screen ratios such as 1:1 (square), 4:3, 16:9, and 16:10.

[0584] The electronic device of this embodiment may have sensors (including those with functions to measure force, displacement, position, velocity, acceleration, angular velocity, rotational speed, distance, light, liquid, magnetism, temperature, chemical substances, sound, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, gradient, vibration, odor, or infrared radiation).

[0585] The electronic device of this embodiment can have a variety of functions. For example, it can have a function to display various information (still images, videos, or text images, etc.) on the display unit, a touch panel function, a function to display a calendar, date, or time, a function to execute various software (programs), a wireless communication function, a function to read programs or data recorded on a recording medium, and so on.

[0586] Figures 35A to 35D illustrate an example of a wearable device that can be worn on the head. These wearable devices have at least one of the following functions: a function to display AR content, a function to display VR content, a function to display SR content, and a function to display MR content. By having an electronic device that has the function to display at least one of the following content types, such as AR, VR, SR, and MR, it is possible to enhance the user's sense of immersion.

[0587] The electronic device 700A shown in Figure 35A and the electronic device 700B shown in Figure 35B each include 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.

[0588] A display device according to one embodiment of the present invention can be applied to the display panel 751. Therefore, a highly reliable electronic device can be made.

[0589] Electronic devices 700A and 700B can project an image displayed on the display panel 751 onto the display area 756 of the optical element 753. Because the optical element 753 is translucent, the user can see the image displayed on the display area superimposed on the transmitted image visible through the optical element 753. Therefore, electronic devices 700A and 700B are electronic devices capable of AR display.

[0590] Electronic devices 700A and 700B may be equipped with cameras capable of capturing images of the area in front of them as imaging units. Furthermore, electronic devices 700A and 700B may each be equipped with acceleration sensors such as gyro sensors to detect the orientation of the user's head and display an image corresponding to that orientation in the display area 756.

[0591] The communications unit has a wireless communication device, which can supply, for example, a video signal. Alternatively, instead of the wireless communication device, or in addition to the wireless communication device, it may be equipped with a connector to which a cable supplying video signals and power potential can be connected.

[0592] Furthermore, electronic devices 700A and 700B are equipped with batteries that can be charged wirelessly, wired, or both.

[0593] The housing 721 may be equipped with a touch sensor module. The touch sensor module has the function of detecting when the outer surface of the housing 721 is touched. The touch sensor module can detect the user's tap or slide operations and perform various processes. For example, a tap operation can be used to pause or resume the video, and a slide operation can be used to fast forward or rewind. Furthermore, by providing a touch sensor module in each of the two housings 721, the range of operations can be expanded.

[0594] Various types of touch sensors can be applied to the touch sensor module. For example, various methods such as capacitive, resistive, infrared, electromagnetic induction, surface acoustic wave, or optical sensors can be used. In particular, it is preferable to apply a capacitive or optical sensor to the touch sensor module.

[0595] When using an optical touch sensor, a photoelectric conversion device (also called a photoelectric conversion element) can be used as the light-receiving element. The active layer of the photoelectric conversion device can be made of either an inorganic semiconductor or an organic semiconductor, or both.

[0596] The electronic device 800A shown in Figure 35C and the electronic device 800B shown in Figure 35D each include 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.

[0597] A display device according to one embodiment of the present invention can be applied to the display unit 820. Therefore, a highly reliable electronic device can be made.

[0598] The display unit 820 is located inside the housing 821, in a position where it can be seen through the lens 832. Furthermore, by displaying different images on a pair of display units 820, a three-dimensional display using parallax can also be performed.

[0599] Electronic devices 800A and 800B can be described as electronic devices for VR. A user wearing electronic device 800A or electronic device 800B can view the image displayed on the display unit 820 through the lens 832.

[0600] It is preferable that electronic devices 800A and 800B each have a mechanism that allows adjustment of the left and right positions of the lens 832 and the display unit 820 so that they are in the optimal position according to the user's eye position. It is also preferable that they have a mechanism that adjusts the focus by changing the distance between the lens 832 and the display unit 820.

[0601] The attachment portion 823 allows the user to attach the electronic device 800A or 800B to their head. Note that, for example, in Figure 35C, it is illustrated as having a shape similar to the temple (joint, or arm, etc.) of eyeglasses, but it is not limited to this. The attachment portion 823 only needs to be wearable by the user; for example, it may be in the shape of a helmet or a band.

[0602] The imaging unit 825 has the function of acquiring external information. The data acquired by the imaging unit 825 can be output to the display unit 820. An image sensor can be used in the imaging unit 825. In addition, multiple cameras may be provided to accommodate multiple angles of view, such as telephoto and wide-angle.

[0603] Although an example with an imaging unit 825 is shown here, any distance measuring sensor (hereinafter also referred to as a detection unit) capable of measuring the distance to an object can be provided. In other words, the imaging unit 825 is one form of a detection unit. As the detection unit, for example, an image sensor or a distance image sensor such as LiDAR (Light Detection and Ranging) can be used. By using the image obtained by the camera and the image obtained by the distance image sensor, more information can be acquired, enabling more accurate gesture control.

[0604] The 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 the display unit 820, housing 821, and mounting unit 823. This eliminates the need for separate audio equipment such as headphones, earphones, or speakers, allowing users to enjoy video and audio simply by wearing the electronic device 800A.

[0605] Electronic devices 800A and 800B may each have input terminals. Cables can be connected to these input terminals to supply, for example, video signals from a video output device and power to charge a battery provided within the electronic device.

[0606] An electronic device according to one aspect of the present invention may have a function for wireless communication with an earphone 750. The earphone 750 has a communication unit (not shown) and has a wireless communication function. The earphone 750 can receive information (e.g., voice data) from the electronic device through its wireless communication function. For example, the electronic device 700A shown in Figure 35A has a function for transmitting information to the earphone 750 through its wireless communication function. Also, for example, the electronic device 800A shown in Figure 35C has a function for transmitting information to the earphone 750 through its wireless communication function.

[0607] Furthermore, the electronic device may have an earphone section. The electronic device 700B shown in Figure 35B has an earphone section 727. For example, the earphone section 727 and the control unit can be connected to each other by a wire. Part of the wiring connecting the earphone section 727 and the control unit may be located inside the housing 721 or the mounting section 723.

[0608] Similarly, the electronic device 800B shown in Figure 35D has an earphone unit 827. For example, the earphone unit 827 and the control unit 824 can be connected to each other by a wire. Part of the wiring connecting the earphone unit 827 and the control unit 824 may be located inside the housing 821 or the mounting unit 823. Also, the earphone unit 827 and the mounting unit 823 may have magnets. This allows the earphone unit 827 to be fixed to the mounting unit 823 by magnetic force, which is preferable as it facilitates storage.

[0609] Furthermore, the electronic device may have an audio output terminal to which earphones or headphones can be connected. The electronic device may also have an audio input terminal and / or an audio input mechanism. For example, a microphone or other sound-collecting device can be used as the audio input mechanism. By having an audio input mechanism, the electronic device may be given the function of a so-called headset.

[0610] Thus, as one embodiment of the present invention, both eyeglass-type (electronic devices 700A and 700B, etc.) and goggle-type (electronic devices 800A and 800B, etc.) are preferred as electronic devices.

[0611] Furthermore, an electronic device according to one aspect of the present invention can transmit information to earphones via wired or wireless means.

[0612] The electronic device 6500 shown in Figure 36A is a portable information terminal that can be used as a smartphone.

[0613] The electronic device 6500 includes a housing 6501, a display unit 6502, a power button 6503, a button 6504, a speaker 6505, a microphone 6506, a camera 6507, and a light source 6508, etc. The display unit 6502 has a touch panel function.

[0614] A display device according to one embodiment of the present invention can be applied to the display unit 6502. Therefore, a highly reliable electronic device can be made.

[0615] Figure 36B is a schematic cross-sectional view of the housing 6501, including the end on the microphone 6506 side.

[0616] A light-transmitting protective member 6510 is provided on the display side of the housing 6501, and the display panel 6511, optical member 6512, touch sensor panel 6513, printed circuit board 6517, and battery 6518 are arranged in the space enclosed by the housing 6501 and the protective member 6510.

[0617] The protective member 6510 is fixed to the display panel 6511, the optical member 6512, and the touch sensor panel 6513 by an adhesive layer (not shown).

[0618] In the area outside the display unit 6502, a portion of the display panel 6511 is folded back, and the FPC 6515 is connected to this folded portion. IC 6516 is mounted on the FPC 6515. The FPC 6515 is connected to terminals provided on the printed circuit board 6517.

[0619] A flexible display according to one embodiment of the present invention can be applied to the display panel 6511. This makes it possible to realize an extremely lightweight electronic device. Furthermore, because the display panel 6511 is extremely thin, it is possible to incorporate a large-capacity battery 6518 while keeping the thickness of the electronic device low. In addition, by folding back a part of the display panel 6511 and placing the connection part with the FPC 6515 on the back of the pixel area, an electronic device with a narrow bezel can be realized.

[0620] Figure 36C shows an example of a television system. The television system 7100 has a display unit 7000 incorporated into a housing 7101. Here, the housing 7101 is shown supported by a stand 7103.

[0621] A display device according to one embodiment of the present invention can be applied to the display unit 7000. Therefore, a highly reliable electronic device can be obtained.

[0622] The television device 7100 shown in Figure 36C can be operated using the operation switches on the housing 7101 and a separate remote control unit 7111. Alternatively, the display unit 7000 may be equipped with a touch sensor, and the television device 7100 can be operated by touching the display unit 7000 with a finger or the like. The remote control unit 7111 may have a display unit that displays information output from the remote control unit 7111. Channels and volume can be controlled and the image displayed on the display unit 7000 can be controlled using the operation keys or touch panel on the remote control unit 7111.

[0623] The television system 7100 is configured to include a receive...

Claims

1. It comprises a first light-emitting element, a second light-emitting element, a first insulating layer, a second insulating layer, a third insulating layer, and a fourth insulating layer. The first light-emitting element comprises a first pixel electrode, a first EL layer on the first pixel electrode, and a common electrode on the first EL layer. The second light-emitting element comprises a second pixel electrode, a second EL layer on the second pixel electrode, and the common electrode on the second EL layer. The first insulating layer covers a portion of the upper surface and sides of the first EL layer, and a portion of the upper surface and sides of the second EL layer. The second insulating layer overlaps with a portion of the upper surface of the first EL layer and a portion of the upper surface of the second EL layer via the first insulating layer. The second insulating layer has a region located between the side surface of the first EL layer and the side surface of the second EL layer, The second insulating layer has a recess in a position overlapping with the region, The third insulating layer has a first region in contact with the upper surface of the first EL layer, The first region is located between the first EL layer and the first insulating layer. The fourth insulating layer has a second region in contact with the upper surface of the second EL layer, The second region is located between the second EL layer and the first insulating layer. The common electrode is provided on the second insulating layer, which is a display device.

2. In claim 1, The second insulating layer has a concave curved shape in the recess, in the display device.

3. In claim 1, A display device wherein the portion of the recess with the minimum height in cross-sectional view does not overlap with either the first EL layer or the second EL layer.

4. In claim 1, The first EL layer comprises a first light-emitting layer and a first functional layer on the first light-emitting layer. The second EL layer comprises a second light-emitting layer and a second functional layer on the second light-emitting layer. A display device in which the first functional layer and the second functional layer each have at least one of the following: a hole injection layer, an electron injection layer, a hole transport layer, an electron transport layer, a hole blocking layer, and an electron blocking layer.

5. In claim 1, The second insulating layer covers at least a portion of the side surface of the first insulating layer, and is a display device.

6. In claim 1, A display device wherein the end of the second insulating layer is located outside the end of the first insulating layer.

7. In claim 1, A display device in which, in a cross-sectional view, the ends of the first insulating layer and the ends of the second insulating layer have a tapered shape with a taper angle of less than 90°.

8. In Claim 1, The third insulating layer has a region that overlaps with the first insulating layer and a region that does not overlap with the first insulating layer. A display device wherein the fourth insulating layer has a region that overlaps with the first insulating layer and a region that does not overlap with the first insulating layer.

9. In claim 8, A display device wherein the second insulating layer covers at least a portion of the side surface of the third insulating layer and at least a portion of the side surface of the fourth insulating layer.

10. In claim 8, In a cross-sectional view, the ends of the third insulating layer and the ends of the fourth insulating layer each have a tapered shape with a taper angle of less than 90°, wherein the display device.

11. In claim 1, The above first insulating layer is an inorganic insulating layer, The second insulating layer is an organic insulating layer, in a display device.

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

13. The display module according to claim 12, An electronic device comprising at least one of a housing, a battery, a camera, a speaker, and a microphone.

14. A first pixel electrode and a second pixel electrode are formed. A first EL film is formed on the first pixel electrode and the second pixel electrode. A first mask film is formed on the first EL film. The first EL film and the first mask film are processed to form a first EL layer on the first pixel electrode and a first mask layer on the first EL layer. A second EL film is formed on the first mask layer and on the second pixel electrode. A second mask film is formed on the second EL film. The second EL film and the second mask film are processed to form a second EL layer on the second pixel electrode and a second mask layer on the second EL layer. An inorganic insulating film is formed on the first mask layer and the second mask layer. An organic insulating film is formed on the inorganic insulating film using a photosensitive material. By performing a first exposure and a first development on the organic insulating film, an organic insulating layer is formed in the region located between the side surface of the first EL layer and the side surface of the second EL layer. Using the first chemical solution, the first etching treatment is performed on the inorganic insulating film using the organic insulating layer as a mask, thereby thinning the film thickness of a portion of the inorganic insulating film. The organic insulating layer is subjected to a second exposure, Using a second chemical solution that functions as a developer, a second development is performed on the organic insulating layer, and a second etching treatment is performed on the inorganic insulating film, the first mask layer, and the second mask layer using the organic insulating layer as a mask, thereby forming recesses in the area of ​​the organic insulating layer that overlap with the area of ​​the organic insulating layer, forming an inorganic insulating layer beneath the organic insulating layer, and further thinning the film thickness of a portion of the first mask layer and a portion of the second mask layer. The organic insulating layer is cured by heat treatment, Using the third chemical solution, the organic insulating layer is used as a mask to perform a third etching process on the first mask layer and the second mask layer, thereby exposing the upper surfaces of the first EL layer and the second EL layer. A method for manufacturing a display device, comprising forming a common electrode on the first EL layer, the second EL layer, and the organic insulating layer.

15. In claim 14, A method for manufacturing a display device, wherein the energy density of the second exposure is lower than the energy density of the first exposure.

16. In claim 14, A method for manufacturing a display device, wherein the first chemical solution functions as a developer.

17. In claim 14, A method for manufacturing a display device, wherein the first chemical solution and the third chemical solution function as a developer.

18. In claim 14, A method for manufacturing a display device, wherein the first mask film and the second mask film contain the same material as the inorganic insulating film.

19. In claim 14, A method for manufacturing a display device, wherein the first mask film, the second mask film, and the inorganic insulating film are each formed using the ALD method.

20. In any one of claims 14 to 19, As the first EL film, a first light-emitting film and a first functional film on the first light-emitting film are formed. As the second EL film, a second light-emitting film and a second functional film on the second light-emitting film are formed. A method for manufacturing a display device, wherein the first functional film and the second functional film each have at least one of the films that are a hole injection layer, an electron injection layer, a hole transport layer, an electron transport layer, a hole blocking layer, and an electron blocking layer.

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