Indication device

Abstract

To provide a highly reliable display device. [Solution] A display device comprising a light-emitting element and an insulating layer arranged to cover the light-emitting element, wherein the light-emitting element has a first conductive layer, an EL layer on the first conductive layer, and a second conductive layer on the EL layer, and the insulating layer has a first layer, a second layer on the first layer, and a third layer on the second layer, wherein the first layer has a function of capturing or fixing at least one of water and oxygen, the second layer has a function of suppressing the diffusion of at least one of water and oxygen, and the third layer has a higher carbon concentration than at least one of the first layer and the second layer.

Description

[Technical Field]

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

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

[0003] In recent years, there has been a demand for higher resolution display panels. Devices requiring high-resolution display panels, such as devices for virtual reality (VR), augmented reality (AR), substitutional reality (SR), and mixed reality (MR), have been actively developed in recent years.

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

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

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

[0007] For example, in the wearable devices for VR, AR, SR, or MR described above, a focus adjustment lens must be provided between the eyes and the display panel. Because the lens magnifies part of the screen, if the resolution of the display panel is low, this can cause a problem of diminishing the sense of realism and immersion.

[0008] Furthermore, display panels are required to have high color reproducibility. In particular, in the above-mentioned devices for VR, AR, SR, or MR, by using a display panel with high color reproducibility, it is possible to display colors that are close to the colors of real objects, thereby enhancing the sense of realism and immersion.

[0009] An object of one embodiment of the present invention is to provide a display device with extremely high resolution.An object of one embodiment of the present invention is to provide a display device with high reliability.An object of one embodiment of the present invention is to provide a display device with high color reproducibility.An object of one embodiment of the present invention is to provide a display device with high luminance.An object of one embodiment of the present invention is to provide a method for manufacturing the above-described display device.

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

[0011] One embodiment of the present invention is a display device that includes a light-emitting element and an insulating layer arranged to cover the light-emitting element. The light-emitting element includes a first conductive layer, an EL layer on the first conductive layer, and a second conductive layer on the EL layer. The insulating layer includes a first layer, a second layer on the first layer, and a third layer on the second layer. The first layer has a function of capturing or fixing at least one of water and oxygen, the second layer has a function of suppressing diffusion of at least one of water and oxygen, and the third layer has a higher carbon concentration than at least one of the first layer and the second layer.

[0012] Another embodiment of the present invention is a display device including: a transistor over a substrate; a first insulating layer over the transistor; a plug disposed to be embedded in the first insulating layer; a light-emitting element over the first insulating layer; and a second insulating layer disposed to cover the light-emitting element. The light-emitting element includes a first conductive layer, an EL layer over the first conductive layer, and a second conductive layer over the EL layer. The plug electrically connects one of a source and a drain of the transistor to the first conductive layer. The second insulating layer includes the first layer, a second layer over the first layer, and a third layer over the second layer. The first layer has a function of capturing or fixing at least one of water and oxygen, the second layer has a function of suppressing diffusion of at least one of water and oxygen, and the third layer has a higher carbon concentration than at least one of the first layer and the second layer.

[0013] In the above structure, a third insulating layer may be provided between the first insulating layer and the light-emitting element, and the third insulating layer may have a function of suppressing the diffusion of at least one of water and oxygen. In the above structure, the third insulating layer preferably contains nitrogen and silicon. In the above structure, the third insulating layer may be in contact with the second insulating layer in a region that does not overlap with the light-emitting element.

[0014] In the above structure, the substrate may be a silicon substrate, and the transistor may have a channel formation region formed of silicon.In the above structure, an oxide semiconductor film may be provided over the substrate, and the transistor may have a channel formation region formed of the oxide semiconductor film.

[0015] In the above structure, the first layer preferably contacts a side surface of the EL layer. In the above structure, the first layer preferably is formed by sputtering. In the above structure, the first layer preferably contains oxygen and aluminum. In the above structure, the first layer may contain oxygen and hafnium.

[0016] In the above structure, the second layer is preferably formed by sputtering.In the above structure, the second layer preferably contains nitrogen and silicon.

[0017] In the above-mentioned configuration, the third layer is preferably formed by an ALD method. In the above-mentioned configuration, the third layer may have a higher hydrogen concentration than at least one of the first layer and the second layer. In the above-mentioned configuration, the third layer may have a lower density than at least one of the first layer and the second layer. In the above-mentioned configuration, the third layer may contain oxygen and aluminum.

[0018] In the above configuration, the side surface of the EL layer may be located inside the side surface of the first conductive layer. In the above configuration, the EL layer may cover the side surface of the first conductive layer. In the above configuration, an insulator may be disposed between the EL layer and the first conductive layer, and the insulator may have an opening above the first conductive layer, so that the EL layer and the first conductive layer contact each other through the opening. [Effects of the Invention]

[0019] According to one aspect of the present invention, it is possible to provide a display device with extremely high resolution, a highly reliable display device, a display device with high color reproducibility, a high brightness display device, or a method for manufacturing the display device.

[0020] Note that the description of these effects does not preclude the existence of other effects. Note that one embodiment of the present invention does not necessarily have all of these effects. Note that effects other than these can be extracted from the description in the specification, drawings, claims, etc. [Brief explanation of the drawings]

[0021] [Figure 1] 1A to 1C are diagrams showing configuration examples of a display device. [Figure 2] 2A to 2C are diagrams showing configuration examples of a display device. [Figure 3] 3A and 3B are diagrams showing configuration examples of a display device. [Figure 4] 4A and 4B are diagrams illustrating an example of the configuration of a display device. [Figure 5] 5A to 5D are diagrams illustrating an example of a method for manufacturing a display device. [Figure 6] 6A to 6D are diagrams illustrating an example of a method for manufacturing a display device. [Figure 7] 7A to 7C are diagrams illustrating an example of a method for manufacturing a display device. [Figure 8] 8A and 8B are diagrams showing configuration examples of a display device. [Figure 9] FIG. 9 is a diagram illustrating an example of the configuration of a display device. [Figure 10] FIG. 10 is a diagram showing an example of the configuration of a display device. [Figure 11] FIG. 11 is a diagram illustrating an example of the configuration of a display device. [Figure 12] 12A and 12B are diagrams showing an example of the configuration of a display module. [Figure 13] 13A and 13B are circuit diagrams showing an example of a display device. [Figure 14] Figures 14A and 14C are circuit diagrams showing an example of a display device, and Figure 14B is a timing chart showing an example of the operation of the display device. [Figure 15] 15A and 15B are diagrams showing configuration examples of electronic devices. [Figure 16] 16A and 16B are diagrams showing configuration examples of electronic devices. [Figure 17] 17A to 17D are diagrams showing configuration examples of a display device. DETAILED DESCRIPTION OF THE INVENTION

[0022] Hereinafter, embodiments will be described with reference to the drawings. However, it will be readily understood by those skilled in the art that the embodiments can be implemented in many different ways and that various changes in form and details can be made without departing from the spirit and scope of the present invention. Therefore, the present invention should not be interpreted as being limited to the following description of the embodiments.

[0023] In the configuration of the invention described below, the same parts or parts having similar functions are denoted by the same reference numerals in different drawings, and repeated explanations thereof will be omitted. In addition, when referring to similar functions, the same hatch pattern may be used and no particular reference numeral may be assigned.

[0024] In the drawings described in this specification, the size of each component, the thickness of a layer, or an area may be exaggerated for clarity, and therefore, the drawings are not necessarily limited to the scale.

[0025] In this specification, ordinal numbers such as "first" and "second" are used to avoid confusion of components and do not limit the number.

[0026] (Embodiment 1) In this embodiment, a display device according to one embodiment of the present invention and a method for manufacturing the display device will be described.

[0027] A display device according to one embodiment of the present invention includes light-emitting elements (also referred to as light-emitting devices) that emit light of different colors. The light-emitting elements include a lower electrode, an upper electrode, and a light-emitting layer (also referred to as a layer containing a light-emitting compound) between them. As the light-emitting elements, electroluminescent elements such as organic EL elements and inorganic EL elements are preferably used. Alternatively, light-emitting diodes (LEDs) may be used.

[0028] The EL element can be an OLED (organic light emitting diode), a QLED (quantum-dot light emitting diode), etc. Examples of light-emitting compounds (also called luminescent materials) contained in EL elements include fluorescent materials, phosphorescent materials, inorganic compounds (such as quantum dot materials), and thermally activated delayed fluorescence (TADF) materials.

[0029] As the light-emitting substance, a substance that emits light of blue, purple, blue-purple, green, yellow-green, yellow, orange, red, etc. may be appropriately used. A substance that emits near-infrared light may also be used.

[0030] The light-emitting layer may contain one or more compounds (host material, assist material) in addition to the light-emitting substance (guest material). As the host material and the assist material, one or more substances having an energy gap larger than the energy gap of the light-emitting substance (guest material) can be selected and used. As the host material and the assist material, it is preferable to use a combination of compounds that form an exciplex. In order to efficiently form an exciplex, it is particularly preferable to combine a compound that easily accepts holes (hole-transporting material) with a compound that easily accepts electrons (electron-transporting material).

[0031] The light-emitting element can be made of either a low molecular weight compound or a high molecular weight compound, and may contain an inorganic compound (such as a quantum dot material).

[0032] A display device according to one embodiment of the present invention can produce light-emitting elements of different colors with extremely high precision. Therefore, a display device with higher resolution than conventional display devices can be realized. For example, a highly precise display device is preferred in which pixels each having one or more light-emitting elements are arranged at a resolution of 2000 ppi or more, preferably 3000 ppi or more, more preferably 5000 ppi or more, and even more preferably 6000 ppi or more, and at a resolution of 20000 ppi or less, or 30000 ppi or less.

[0033] More specific configuration examples and manufacturing method examples will be described below with reference to the drawings.

[0034] [Configuration example 1] Fig. 1A is a cross-sectional schematic diagram illustrating a display device according to one embodiment of the present invention. Fig. 1B is an enlarged view of a region A sandwiched between light-emitting elements 120 shown in Fig. 1A. The display device 100 includes a light-emitting element 120R, a light-emitting element 120G, and a light-emitting element 120B. The light-emitting element 120R is a light-emitting element that emits red light, the light-emitting element 120G is a light-emitting element that emits green light, and the light-emitting element 120B is a light-emitting element that emits blue light.

[0035] In the following, when describing matters common to the light-emitting elements 120R, 120G, and 120B, the symbols added to the reference numerals may be omitted and the elements may be referred to as the light-emitting elements 120. Similarly, the EL layers 115R, 115G, and 115B described below may also be referred to as the EL layer 115. The EL layer 115R is included in the light-emitting element 120R. Similarly, the EL layer 115G is included in the light-emitting element 120G, and the EL layer 115B is included in the light-emitting element 120B. Similarly, the conductive layers 114R, 114G, and 114B described below may also be referred to as the conductive layer 114. The conductive layer 114R is included in the light-emitting element 120R. Similarly, the conductive layer 114G is included in the light-emitting element 120G, and the conductive layer 114B is included in the light-emitting element 120B.

[0036] The light-emitting element 120 includes a conductive layer 111 functioning as a lower electrode, an EL layer 115, and a conductive layer 116 functioning as an upper electrode. The conductive layer 111 is reflective to visible light. The conductive layer 116 is transmissive and reflective to visible light. Alternatively, the conductive layer 116 may be semi-transmissive and semi-reflective to visible light. The EL layer 115 includes a light-emitting compound. The EL layer 115 includes at least the light-emitting layer included in the light-emitting element 120.

[0037] The light-emitting element 120 can be an electroluminescent element that emits light by applying a potential difference between the conductive layer 111 and the conductive layer 116 and then receiving a current flowing through the EL layer 115. In particular, it is preferable to use an organic EL element that uses a light-emitting organic compound for the EL layer 115. Furthermore, it is preferable that the light-emitting element 120 is an element that emits white light whose emission spectrum has two or more peaks in the visible light region.

[0038] The top surface of the conductive layer 111 is reflective to visible light.

[0039] The display device 100 includes a substrate 101 having a semiconductor circuit and a light-emitting element 120 on the substrate 101. The display device 100 shown in FIG. 1A also includes an insulating layer 121 on the substrate 101, a light-emitting element 120 on the insulating layer 121, and an insulating layer 124 arranged to cover the light-emitting element 120. The insulating layer 124 is preferably in contact with the top and side surfaces of the conductive layer 116, the side surfaces of the EL layer 115, and the side surfaces of the conductive layer 111. The insulating layer 124 may also be in contact with the insulating layer 121 in a region that does not overlap with the light-emitting element 120.

[0040] The substrate 101 can be a circuit substrate having transistors, wirings, and the like. When a passive matrix system or a segment system is applicable, an insulating substrate such as a glass substrate can be used as the substrate 101. The substrate 101 is a substrate on which a circuit (also referred to as a pixel circuit) for driving each light-emitting element is provided. The substrate 101 may also be provided with a semiconductor circuit that functions as a driver circuit for driving the pixel circuit. The semiconductor elements constituting such a pixel circuit or semiconductor circuit may be formed using a semiconductor substrate such as a silicon substrate or an oxide semiconductor film. A more specific example of the structure of the substrate 101 will be described later.

[0041] In the display device 100 shown in FIG. 1A, the substrate 101 and the conductive layer 111 of the light-emitting element 120 are electrically connected via a plug 131. The plug 131 is formed so as to be embedded in an opening provided in the insulating layer 121. The conductive layer 111 is formed on the insulating layer 121. The conductive layer 111 is provided on the plug 131. The conductive layer 111 and the plug 131 are electrically connected. Furthermore, it is preferable that the conductive layer 111 be in contact with the upper surface of the plug 131. Furthermore, the conductive layer 111 may be configured to be in contact with the upper surface of the insulating layer 121.

[0042] The insulating layer 124 preferably functions as a barrier insulating film against at least one of water and oxygen. More preferably, it functions as a barrier insulating film against hydrogen, a substance to which hydrogen is bonded (for example, water (H2O)), oxygen, chlorine, and the like. The insulating layer 124 preferably includes a layer having a function of suppressing diffusion of at least one of water and oxygen. More preferably, it includes a layer having a function of suppressing diffusion of hydrogen, a substance to which hydrogen is bonded (for example, water (H2O)), oxygen, chlorine, and the like. The insulating layer 124 preferably includes a layer having a function of capturing or fixing (also referred to as gettering) at least one of water and oxygen. More preferably, it includes a layer having a function of capturing or fixing hydrogen, a substance to which hydrogen is bonded (for example, water (H2O)), oxygen, chlorine, and the like.

[0043] In this specification, a barrier insulating film refers to an insulating film having barrier properties. In this specification, the term "barrier properties" refers to a function of suppressing the diffusion of a corresponding substance (also referred to as low permeability), or a function of capturing or fixing a corresponding substance.

[0044] 1B, the insulating layer 124 preferably includes a layer 124a, a layer 124b on the layer 124a, and a layer 124c on the layer 124b. The layer 124a has the function of capturing or adhering at least one of water and oxygen. The layer 124b has the function of suppressing the diffusion of at least one of water and oxygen. The layer 124c has good coating properties.

[0045] The layer 124a is disposed at least between the layer 124b and the EL layer 115. The layer 124a is preferably in contact with the top surface and side surfaces of the conductive layer 116, the side surfaces of the EL layer 115, and the side surfaces of the conductive layer 111. The layer 124a may be in contact with the insulating layer 121 in a region sandwiched between the conductive layers 111. The layer 124b is provided to cover the layer 124a and is preferably in contact with the top surface of the layer 124a.

[0046] In this way, by providing layers 124a and 124b, impurities such as oxygen and water in light-emitting element 120 can be captured or fixed to layer 124a in the region covered by layer 124b, thereby reducing the impurities contained in light-emitting element 120. In particular, since layer 124a is provided in contact with the side surface of EL layer 115, to which impurities are likely to adhere during processing, it is possible to prevent a different layer made of the impurities from being formed on the side surface of EL layer 115. Furthermore, layer 124b prevents impurities such as oxygen and water from diffusing from above insulating layer 124 to light-emitting element 120, thereby preventing an increase in impurities in the light-emitting element.

[0047] The layer 124c is provided to cover the layer 124b and is preferably in contact with the upper surface of the layer 124b. The layer 124c is preferably formed by atomic layer deposition (ALD), which has good coverage.

[0048] Here, layer 124b has irregularities that reflect the shape of the surface on which it is formed, that is, the stepped shapes of conductive layer 111, EL layer 115, and conductive layer 116. This may cause discontinuities or the like to form in layer 124b. However, as described above, by providing layer 124c with good coverage, even if discontinuities or the like form in layer 124b, layer 124c can fill in the discontinuities. This maintains layer 124b's ability to suppress the diffusion of impurities such as water and oxygen.

[0049] As described above, according to one embodiment of the present invention, impurities such as water or oxygen in a light-emitting element can be reduced and deterioration of the light-emitting element can be prevented, so that a highly reliable display device can be provided.

[0050] 1C , an insulating layer 122 may be further provided between the insulating layer 121 and the conductive layer 111 and insulating layer 124. Like the insulating layer 124, the insulating layer 122 preferably functions as a barrier insulating film against at least one of water and oxygen. As the insulating layer 122, it is preferable to use either or both of an insulating layer having a similar function to the layer 124a and an insulating layer having a similar function to the layer 124b. For example, the insulating layer 122 may be a stacked layer including an insulating layer having a similar function to the layer 124b and an insulating layer having a similar function to the layer 124a on the insulating layer.

[0051] By providing the insulating layer 122, which functions as a barrier insulating film against water, oxygen, etc., below the light emitting element 120, it is possible to prevent impurities such as water or oxygen contained in the interlayer insulating film and semiconductor circuits such as pixel circuits provided below the light emitting element 120 from diffusing into the light emitting element 120. This makes it possible to prevent the light emitting element 120 from deteriorating.

[0052] Furthermore, when an oxide semiconductor is provided in the semiconductor circuit, impurities such as water or hydrogen contained in the light-emitting element and the interlayer insulating film over the light-emitting element can be prevented from diffusing into the oxide semiconductor, thereby preventing deterioration in the electrical characteristics and reliability of the element including the oxide semiconductor.

[0053] 1C , the insulating layer 124 is preferably in contact with the insulating layer 122 in a region that does not overlap with the conductive layer 111. Here, the insulating layer 124 is in contact with the top and side surfaces of the conductive layer 116, the side surfaces of the EL layer 115, and the side surfaces of the conductive layer 111. This results in a structure in which the light-emitting element 120 is surrounded by the insulating layers 124 and 122. By providing the layer 124a in the region surrounded by the insulating layers 124 and 122, impurities such as water or oxygen in the light-emitting element can be more efficiently captured or fixed to the layer 124a.

[0054] In the display device 100 shown in FIGS. 1A to 1C, the EL layer 115 and the conductive layer 116 are separated between adjacent light-emitting elements of different colors. This prevents leakage current from flowing through the EL layer 115 between adjacent light-emitting elements of different colors. This suppresses light emission caused by the leakage current, enabling a high-contrast display. Furthermore, even when the resolution is increased, a highly conductive material can be used for the EL layer 115, broadening the range of material options and facilitating improved efficiency, reduced power consumption, and improved reliability.

[0055] In the display device 100, the EL layer 115 and the conductive layer 116 are preferably processed so as to be continuous without being separated between pixels exhibiting the same color. For example, the EL layer 115 and the conductive layer 116 can be processed into a striped pattern. This allows the conductive layers 116 of all light-emitting elements to be applied with a predetermined potential without being in a floating state.

[0056] The EL layer 115 and the conductive layer 116 may be formed into an island pattern by film formation using a shadow mask such as a metal mask or an FMM (fine metal mask, high-resolution metal mask). However, it is preferable to use a processing method that does not use a metal mask or an FMM. A typical example of such a processing method is photolithography. Other methods that can be used include nanoimprinting and sandblasting. In this specification, a device fabricated using a metal mask or an FMM may be referred to as a device with an MM (metal mask) structure. In this specification, a device fabricated without using a metal mask or an FMM may be referred to as a device with an MML (metal maskless) structure.

[0057] This makes it possible to form extremely fine patterns in devices with the MML structure, which allows for improved definition and aperture ratio compared to devices with the MM structure.

[0058] As shown in FIG. 1A or 1C, an edge of the EL layer 115 may be configured to be approximately aligned with an edge of the conductive layer 111. Alternatively, an edge of the conductive layer 116 may be configured to be approximately aligned with an edge of the conductive layer 111. Alternatively, one edge of the EL layer 115 may be positioned outside the conductive layer 111, and the other edge may be approximately aligned with an edge of the conductive layer 111. Alternatively, one edge of the conductive layer 116 may be positioned outside the conductive layer 111, and the other edge may be approximately aligned with an edge of the conductive layer 111. Alternatively, as shown in FIG. 2A, an edge of the EL layer 115 may be positioned inside the edge of the conductive layer 111 in the cross section of the display device 100.

[0059] The conductive layer 116 may be disposed so as not to short-circuit at least with the conductive layer 111. For example, as shown in FIG. 2B , the EL layer 115 may be disposed so that an end of the EL layer 115 is positioned outside an end of the conductive layer 111 in the cross section of the display device 100. The end of the EL layer 115 covers an end of the conductive layer 111. By positioning the end of the EL layer 115 outside the end of the conductive layer 111, it is possible to prevent a short circuit between the conductive layer 111 and the conductive layer 116. Furthermore, as shown in FIG. 2B , the conductive layer 116 may be disposed so that an end of the conductive layer 116 is positioned outside the end of the conductive layer 111 in the cross section of the display device 100.

[0060] 2C, a configuration may be adopted in which an insulator 117 is provided to cover the end of the conductive layer 116. The insulator 117 may also be called a bank, a partition wall, a barrier, an embankment, or the like. The insulator 117 is provided so as to expose the upper surface of the conductive layer 111. By providing the insulator 117, it is possible to prevent a short circuit between the conductive layer 111 and the conductive layer 116.

[0061] 2A to 2C show a structure in which the insulating layer 124 is provided, similar to FIG. 1A, but the present invention is not limited to this and may have the same structure as that shown in FIG. 1C.

[0062] [Light-emitting element] The light-emitting element that can be used for the light-emitting element 120 can be a self-luminous element, and includes elements whose brightness is controlled by current or voltage. For example, an LED, an organic EL element, an inorganic EL element, etc. can be used. In particular, it is preferable to use an organic EL element.

[0063] The light-emitting element may be of a top emission type, a bottom emission type, a dual emission type, etc. A conductive film that transmits visible light is used for the electrode from which light is extracted. It is also preferable to use a conductive film that reflects visible light for the electrode from which light is not extracted.

[0064] In one embodiment of the present invention, it is particularly preferable to use a top-emission type light-emitting element that emits light to the side opposite to the formation surface side, or a dual-emission type light-emitting element that emits light to both the formation surface side and the side opposite to the formation surface side.

[0065] The EL layer 115 includes at least a light-emitting layer. The EL layer 115 may further include a layer containing a substance with high hole-injection properties, a substance with high hole-transport properties, a hole-blocking material, a substance with high electron-transport properties, a substance with high electron-injection properties, or a bipolar substance (a substance with high electron-transport properties and high hole-transport properties), as a layer other than the light-emitting layer.

[0066] Both low molecular weight compounds and high molecular weight compounds, and inorganic compounds may be used for the EL layer 115. The layers constituting the EL layer 115 can be formed by methods such as vapor deposition (including vacuum deposition), transfer, printing, inkjet, and coating.

[0067] When a voltage higher than the threshold voltage of the light-emitting element 120 is applied between the cathode and anode, holes are injected from the anode side and electrons are injected from the cathode side into the EL layer 115. The injected electrons and holes recombine in the EL layer 115, causing the luminescent material contained in the EL layer 115 to emit light.

[0068] Here, the EL layer 115 used in the light-emitting element 120B is referred to as EL layer 115B, the EL layer 115 used in the light-emitting element 120G is referred to as EL layer 115G, and the EL layer 115 used in the light-emitting element 120R is referred to as EL layer 115R. EL layer 115B contains a light-emitting material that emits B (blue) light. EL layer 115G contains a light-emitting material that emits G (green). EL layer 115R contains a light-emitting material that emits R (red). A structure in which each light-emitting element is painted with a different light-emitting color (here, blue (B), green (G), and red (R)) is sometimes called an SBS (Side By Side) structure. This configuration makes it possible to provide a display device with lower power consumption than a display device with a structure in which white light-emitting elements are colored by colored layers.

[0069] The above-described light-emitting layer and the layer containing a substance with high hole-injection properties, a substance with high hole-transport properties, a substance with high electron-transport properties, a substance with high electron-injection properties, a bipolar substance, or the like may each contain an inorganic compound such as quantum dots or a polymer compound (oligomer, dendrimer, polymer, or the like). For example, quantum dots can be used in the light-emitting layer to function as a light-emitting material.

[0070] Examples of quantum dot materials that can be used include colloidal quantum dot materials, alloy quantum dot materials, core-shell quantum dot materials, and core quantum dot materials. Materials containing elements from groups 12 and 16, 13 and 15, or 14 and 16 may also be used. Quantum dot materials containing elements such as cadmium, selenium, zinc, sulfur, phosphorus, indium, tellurium, lead, gallium, arsenic, and aluminum may also be used.

[0071] A conductive film that transmits visible light and can be used for the conductive layer 116 or the like can be formed using, for example, indium oxide, indium tin oxide, indium zinc oxide, zinc oxide, zinc oxide doped with gallium, or the like. Metal materials such as gold, silver, platinum, magnesium, nickel, tungsten, chromium, molybdenum, iron, cobalt, copper, palladium, or titanium, alloys containing these metal materials, or nitrides of these metal materials (e.g., titanium nitride), can also be used by forming them thin enough to have light-transmitting properties. A stacked film of any of the above materials can also be used as the conductive layer. For example, a stacked film of an alloy of silver and magnesium and indium tin oxide is preferably used because it can increase conductivity. Graphene or the like may also be used.

[0072] The semi-transmitting and semi-reflective conductive film that can be used for the conductive layer 116 preferably has a reflectance to visible light (for example, reflectance to light of a predetermined wavelength in the range of 400 nm to 700 nm) of 20% to 80% inclusive, preferably 40% to 70% inclusive. The reflectance to visible light of a reflective conductive film is preferably 40% to 100% inclusive, preferably 70% to 100% inclusive. The reflectance to visible light of a light-transmitting conductive film is preferably 0% to 40% inclusive, preferably 0% to 30% inclusive.

[0073] The conductive layer 111 preferably includes a conductive film that reflects visible light in a portion thereof located on the EL layer 115 side. For example, the conductive layer 111 can be made of a metal material such as aluminum, gold, platinum, silver, nickel, tungsten, chromium, molybdenum, iron, cobalt, copper, or palladium, or an alloy containing any of these metal materials. Copper is preferable because it has a high reflectance to visible light. Aluminum is also preferable because it is easy to process since electrodes can be easily etched and has a high reflectance to visible light and near-infrared light. Lanthanum, neodymium, germanium, or the like may be added to the above metal material or alloy. An alloy containing aluminum with titanium, nickel, or neodymium (aluminum alloy) may also be used. An alloy containing silver with copper, palladium, magnesium, or the like may also be used. An alloy containing silver and copper is preferable because it has high heat resistance.

[0074] The conductive layer 111 may also have a structure in which a conductive metal oxide film is stacked over a conductive film that reflects visible light. Such a structure can suppress oxidation and corrosion of the conductive film that reflects visible light. For example, stacking a metal film or a metal oxide film in contact with an aluminum film or an aluminum alloy film can suppress oxidation. Examples of materials for such metal films and metal oxide films include titanium and titanium oxide. Alternatively, the conductive film that transmits visible light may be stacked with a film made of a metal material. For example, a stacked film of silver and indium tin oxide, or a stacked film of an alloy of silver and magnesium and indium tin oxide can be used.

[0075] 3A, the conductive layer 111 may have a structure in which a conductive layer 111a is provided as a lower conductive layer and a conductive layer 111b is provided as an upper conductive layer on the conductive layer 111a. In such a structure, a conductive film that reflects visible light is preferably used as the conductive layer 111b. The reflectance of the conductive layer 111a may be lower than that of the conductive layer 111b. A material with high conductivity may be used as the conductive layer 111a. A material with excellent processability may be used as the conductive layer 111a.

[0076] The conductive layer 111b is preferably formed using the same materials and structures as those that can be used for the conductive layer 111.

[0077] The conductive layer 111a may be made of, for example, a metal material such as gold, silver, platinum, magnesium, nickel, tungsten, chromium, molybdenum, iron, cobalt, copper, palladium, titanium, yttrium, zirconium, or tantalum, an alloy containing these metal materials, or a nitride of these metal materials (e.g., titanium nitride).

[0078] When aluminum is used for conductive layer 111 or conductive layer 111b, a thickness of preferably 40 nm or more, more preferably 70 nm or more can be used to sufficiently increase the reflectance of visible light, etc. When silver is used for conductive layer 111 or conductive layer 111b, a thickness of preferably 70 nm or more, more preferably 100 nm or more can be used to sufficiently increase the reflectance of visible light, etc.

[0079] For example, tungsten can be used for the conductive layer 111a, and aluminum or an aluminum alloy can be used for the conductive layer 111b. The conductive layer 111b may have a structure in which titanium oxide is provided in contact with an upper portion of aluminum or an aluminum alloy. Alternatively, the conductive layer 111b may have a structure in which titanium is provided in contact with an upper portion of aluminum or an aluminum alloy, and titanium oxide is provided in contact with an upper portion of the titanium.

[0080] Alternatively, the conductive layers 111a and 111b may both be made of a material and have a structure selected from the materials and structures that can be used for the conductive layer 111 described above.

[0081] The conductive layer 111 may also be a stacked film of three or more layers.

[0082] 3A shows a configuration in which insulating layer 124 is provided, similar to Fig. 1A, but the present invention is not limited to this. In the configuration shown in Fig. 3A, insulating layer 122 may be further provided, similar to the structure shown in Fig. 1C.

[0083] Examples of materials that can be used for the plug 131 include metals such as aluminum, titanium, chromium, nickel, copper, yttrium, zirconium, molybdenum, gold, silver, platinum, magnesium, iron, cobalt, palladium, tantalum, and tungsten, alloys containing these metal materials, and nitrides of these metal materials. Also, as the plug 131, a film containing these materials can be used as a single layer or as a multilayer structure. Examples of suitable structures include a single-layer structure of an aluminum film containing silicon, a two-layer structure in which an aluminum film is laminated on a titanium film, a two-layer structure in which an aluminum film is laminated on a tungsten film, a two-layer structure in which a copper film is laminated on a copper-magnesium-aluminum alloy film, a two-layer structure in which a copper film is laminated on a titanium film, a two-layer structure in which a copper film is laminated on a tungsten film, a three-layer structure in which a titanium film or titanium nitride film is laminated on top of an aluminum film or copper film, and a titanium film or titanium nitride film is further formed on top of that, and a three-layer structure in which a molybdenum film or molybdenum nitride film is laminated on top of an aluminum film or copper film, and a molybdenum film or molybdenum nitride film is further formed on top of that. Oxides such as indium oxide, tin oxide, or zinc oxide may also be used. Furthermore, using copper containing manganese is preferable because it improves the controllability of the shape by etching.

[0084] The electrodes constituting the light-emitting element may be formed by vapor deposition or sputtering. Alternatively, they may be formed by a discharge method such as an ink-jet method, a printing method such as a screen printing method, or a plating method.

[0085] The insulating layer 124 can be formed using an oxide, a nitride, an oxynitride, or a nitride oxide containing at least one of aluminum, hafnium, magnesium, gallium, indium, zinc, and silicon. Alternatively, a stacked film of any of these materials can be used. For example, aluminum oxide, hafnium oxide, hafnium aluminate, magnesium oxide, gallium oxide, indium gallium zinc oxide, silicon oxide, silicon nitride, silicon oxynitride, silicon nitride oxide, or the like can be used.

[0086] The layer 124a having the function of capturing or fixing impurities such as water or oxygen is, for example, an aluminum oxide (AlO x :x is any number greater than 0), or hafnium oxide (HfO y It is preferable to use a metal oxide such as aluminum oxide (where y is any number greater than 0). When aluminum oxide is used for the layer 124a, the layer 124a becomes an insulator containing at least oxygen and aluminum. When hafnium oxide is used for the layer 124a, the layer 124a becomes an insulator containing at least oxygen and hafnium.

[0087] The layer 124a preferably contains many oxygen vacancies. In metal oxides containing many oxygen vacancies, many dangling bonds may be formed, and these dangling bonds may have the property of capturing or fixing impurities such as water or oxygen. By using such a metal oxide containing many oxygen vacancies, impurities such as water or oxygen can be captured or fixed in the layer 124a. In particular, it is preferable to capture or fix impurities such as water or oxygen attached to the side surfaces of the EL layer 115.

[0088] The layer 124a is preferably formed by sputtering. Sputtering can be used to form the layer without using impurities such as water in the film formation gas, which can reduce the increase in the concentration of impurities such as water in the layer 124a and the light-emitting element 120. When sputtering is used to form the layer, it is preferable to reduce the amount of oxygen in the film formation gas or to not include oxygen in the film formation gas. This can reduce the increase in oxygen in the layer 124a and the light-emitting element 120. Furthermore, the formed layer 124a can have many oxygen vacancies.

[0089] The layer 124a may also be made of a metal oxide having an amorphous structure. The layer 124a may have a crystalline region formed in a portion thereof. The layer 124a may also have a multilayer structure in which a layer having an amorphous structure and a layer having a crystalline region are stacked. For example, the layer 124a may have a stacked structure in which a layer having a crystalline region, typically a layer having a polycrystalline structure, is formed on a layer having an amorphous structure.

[0090] The layer 124b having the function of suppressing the diffusion of impurities such as water or oxygen is made of silicon nitride (SiN x (where x is any number greater than 0). In this case, the layer 124b is an insulator containing at least nitrogen and silicon. In order to suppress the diffusion of impurities such as water or oxygen, the layer 124b preferably has a film thickness of 10 nm or more, for example, about 20 nm to 100 nm, or about 20 nm to 50 nm, on the conductive layer 116.

[0091] Furthermore, the layer 124b is preferably formed by sputtering. Sputtering allows metal nitride to be formed without using impurities such as water or oxygen in the film formation gas, which reduces the increase in the concentration of impurities such as water or oxygen in the layers 124b, 124a, and the light-emitting element 120.

[0092] Layer 124c, which has good coverage, may be made of an insulating material that can be used for the insulating layer 124. For example, aluminum oxide, hafnium oxide, or the like formed by the ALD method is preferably used. When forming a metal oxide film by the ALD method, HO, O, or the like is used as an oxidizing agent. However, since layers 124b and 124a are formed before layer 124c is formed, it is possible to reduce the incorporation of impurities such as water or oxygen into the EL layer 115, etc.

[0093] Note that some precursors used in the ALD method contain impurities such as hydrogen or carbon. Therefore, films formed by the ALD method may contain more impurities such as hydrogen or carbon than films formed by other film formation methods. Therefore, the layer 124c may have a higher carbon concentration than at least one of the layers 124a and 124b formed by sputtering. Furthermore, the layer 124c may have a higher hydrogen concentration than at least one of the layers 124a and 124b formed by sputtering. Note that the amount of impurities such as hydrogen or carbon can be quantified using energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), secondary ion mass spectrometry (SIMS), or the like.

[0094] Furthermore, films formed by the ALD method tend to have a lower density than films formed by the sputtering method. Therefore, the layer 124c may have a lower density than at least one of the layers 124a and 124b formed by the sputtering method. The density can be measured using X-ray reflectometry (XRR) or the like.

[0095] The ALD method includes a thermal ALD method in which a reaction between a precursor and a reactant is carried out using only thermal energy, a plasma enhanced ALD method in which a plasma excited reactant is used, etc. Any ALD method may be used as long as the film can be formed at a temperature at which the EL layer 115 is not deteriorated (for example, from room temperature to 100° C.).

[0096] The insulating layer 122 may also be formed using the insulating material that can be used for the layer 124a or the layer 124b. The insulating layer 122 may also have a stacked-layer structure. For example, when the insulating layer 122 has a two-layer structure, an aluminum oxide film formed by sputtering can be provided over a silicon nitride film formed by sputtering.

[0097] The insulating layer 121 functions as an interlayer insulating film and preferably has a low dielectric constant. By using a material with a low dielectric constant as the interlayer film, parasitic capacitance occurring between wirings can be reduced. For example, the insulating layer 121 may be formed using silicon oxide, silicon oxynitride, silicon oxide to which fluorine has been added, silicon oxide to which carbon has been added, silicon oxide to which carbon and nitrogen have been added, silicon oxide having vacancies, or the like as appropriate. In this case, recesses may be formed in the surface of the insulating layer 121 on which the conductive layer 111 is not provided. For example, recesses are formed by etching the insulating layer 121 during an etching step when the conductive layer 111 is formed.

[0098] Also, the insulating material that can be used for the insulating layer 121 may be used for the insulator 117 shown in FIG. 2C.

[0099] 1C, the insulating layer 122 is in contact with the conductive layer 111 and the insulating layer 124. Alternatively, as shown in FIG. 3B, for example, an insulating layer 125 may be provided between the insulating layer 122 and the conductive layer 111 and the insulating layer 124. The insulating layer 125 may be made of an insulating material that can be used for the insulating layer 121. In this case, recesses may be formed in the surface of the insulating layer 125 where the conductive layer 111 is not provided. For example, recesses are formed by etching the insulating layer 125 during an etching step when forming the conductive layer 111.

[0100] 4A, a white-emitting light-emitting substance may be used as the EL layer 115 of the light-emitting element 120. In this case, a colored layer overlapping the light-emitting element 120 may be provided, as described later. When a white-emitting light-emitting substance is used as the EL layer 115, the EL layer 115 preferably contains two or more types of light-emitting substances. For example, white light can be obtained by selecting light-emitting substances such that the respective emissions of the two or more light-emitting substances have a complementary color relationship. For example, it is preferable to include two or more light-emitting substances that emit light of R (red), G (green), B (blue), Y (yellow), O (orange), etc., or light-emitting substances that emit light containing two or more spectral components of R, G, and B. It is also preferable to use a light-emitting element whose emission spectrum has two or more peaks in the wavelength range of the visible light region (e.g., 350 nm to 750 nm). It is also preferable that the emission spectrum of a material having a peak in the yellow wavelength region also contains spectral components in the green and red wavelength regions.

[0101] The EL layer 115 may have a laminated structure in which an emitting layer containing an emitting material that emits one color and an emitting layer containing an emitting material that emits another color are stacked. For example, the multiple emitting layers in the EL layer 115 may be stacked in contact with each other, or may be stacked via a region that does not contain any emitting material. For example, a structure in which a region that contains the same material (e.g., host material, assist material) as the fluorescent or phosphorescent emitting layer but does not contain any emitting material may be provided between the fluorescent emitting layer and the phosphorescent emitting layer. This facilitates fabrication of the light-emitting element and reduces the driving voltage.

[0102] Furthermore, the light emitting element 120 may be a single element having one EL layer, or may be a tandem element in which a plurality of EL layers are stacked with a charge generating layer interposed therebetween.

[0103] As shown in Fig. 4A, the EL layer 115 may be provided in common across all the light-emitting elements 120. In Fig. 4A, a continuous EL layer 115 is provided so as to cover the conductive layer 111 of each light-emitting element 120. Also, as shown in Fig. 4A, the conductive layer 116 may be provided in common across the light-emitting element 120R, the light-emitting element 120G, and the light-emitting element 120B. The conductive layer 116 functions, for example, as an electrode to which a common potential is applied. By providing the conductive layer in common, the number of steps for manufacturing the light-emitting element 120 can be reduced, which is preferable.

[0104] 4B, in the light-emitting element 120, a conductive layer 114 (referring to conductive layers 114B, 114G, and 114R) may be provided between the conductive layer 111 and the EL layer 115. The conductive layer 114 has a function of transmitting visible light.

[0105] The above-described conductive film that is transparent to visible light can be used as the conductive layer 114. Alternatively, the above-described conductive film that reflects visible light can be formed thin enough to transmit visible light as the conductive layer 114. Furthermore, by using a stacked structure of the conductive film and the above-described conductive film that transmits visible light, the conductivity and mechanical strength can be increased.

[0106] 4B, the conductive layer 114 is disposed between the conductive layer 111 and the EL layer 115. The conductive layer 114 is located on the conductive layer 111. Here, the EL layer 115 is preferably provided so as to cover the edge of the conductive layer 114.

[0107] 4B, the conductive layer 114 provided in each light-emitting element 120 preferably has a different thickness for each light-emitting element. Of the three conductive layers 114, conductive layer 114B is the thinnest, and conductive layer 114R is the thickest. Here, the distance between the upper surface of conductive layer 111 and the lower surface of conductive layer 116 (i.e., the interface between conductive layer 116 and EL layer 115) in each light-emitting element is the largest in light-emitting element 120R and the smallest in light-emitting element 120B. By changing the distance between the upper surface of conductive layer 111 and the lower surface of conductive layer 116 in each light-emitting element, the optical distance (optical path length) in each light-emitting element can be changed.

[0108] Of the three light-emitting elements, light-emitting element 120R has the longest optical path length and therefore emits light R, in which light of the longest wavelength is intensified. On the other hand, light-emitting element 120B has the shortest optical path length and therefore emits light B, in which light of the shortest wavelength is intensified. Light-emitting element 120G emits light G, in which light of an intermediate wavelength is intensified. For example, light R can be light in which red light is intensified, light G can be light in which green light is intensified, and light B can be light in which blue light is intensified.

[0109] With this configuration, it is not necessary to create separate EL layers for the light-emitting elements 120 for each light-emitting element of a different color, and color display with high color reproducibility can be achieved using elements with the same configuration. Also, it becomes possible to arrange the light-emitting elements 120 at an extremely high density. For example, a display device with a resolution of over 5000 ppi can be realized.

[0110] The optical distance between the surface of the conductive layer 111 that reflects the visible light of each light-emitting element and the conductive layer 116 that is semi-transmissive and semi-reflective with respect to the visible light is preferably adjusted to be mλ / 2 (m is a natural number, provided that m is not 0) or in the vicinity thereof with respect to the wavelength λ of the light whose intensity is to be enhanced.

[0111] Note that the above-described optical distance is strictly related to the product of the physical distance between the reflecting surface of the conductive layer 111 and the reflecting surface of the semi-transmissive and semi-reflective conductive layer 116 and the refractive index of the layer provided therebetween. Therefore, it is difficult to adjust it precisely. For this reason, it is preferable to adjust the optical distance assuming the surfaces of the conductive layer 111 and the semi-transmissive and semi-reflective conductive layer 116 as reflecting surfaces, respectively.

[0112] Also, as will be described later, by providing a colored layer that overlaps with the light-emitting element 120, the color purity of the light from the light-emitting element can be enhanced.

[0113] The light-emitting element 120 may have a structure in which a plurality of EL layers are stacked. For example, the EL layer 115 may have a structure in which an EL layer 115B having a light-emitting substance that emits blue light, an EL layer 115G having a light-emitting substance that emits green light, and an EL layer 115R having a light-emitting substance that emits red light are stacked. Each EL layer may have an electron injection layer, an electron transport layer, a charge generation layer, a hole transport layer, a hole injection layer, etc. in addition to the layer containing the light-emitting compound. A charge generation layer may be provided between the EL layer 115B and the EL layer 115G. Also, a charge generation layer may be provided between the EL layer 115G and the EL layer 115R.

[0114] <Example of the structure of the EL layer> 17A, the EL layer 115 of the light-emitting element 120 can be composed of multiple layers such as a layer 4420, a light-emitting layer 4411, and a layer 4430. The layer 4420 can have, for example, a layer containing a substance with high electron injection properties (electron injection layer) and a layer containing a substance with high electron transport properties (electron transport layer). The light-emitting layer 4411 contains, for example, a light-emitting compound. The layer 4430 can have, for example, a layer containing a substance with high hole injection properties (hole injection layer) and a layer containing a substance with high hole transport properties (hole transport layer).

[0115] A structure having the layer 4420, the light-emitting layer 4411, and the layer 4430 provided between a pair of electrodes can function as a single light-emitting unit, and the structure of FIG. 17A is referred to as a single structure in this specification.

[0116] 17B shows a modified example of the EL layer 115 included in the light-emitting element 120 shown in Fig. 17A. Specifically, the light-emitting element 120 shown in Fig. 17B includes a layer 4430-1 on the conductive layer 111, a layer 4430-2 on the layer 4430-1, a light-emitting layer 4411 on the layer 4430-2, a layer 4420-1 on the light-emitting layer 4411, a layer 4420-2 on the layer 4420-1, and a conductive layer 116 on the layer 4420-2. For example, when the conductive layer 111 is an anode and the conductive layer 116 is a cathode, the layer 4430-1 functions as a hole injection layer, the layer 4430-2 functions as a hole transport layer, the layer 4420-1 functions as an electron transport layer, and the layer 4420-2 functions as an electron injection layer. Alternatively, when the conductive layer 111 is used as a cathode and the conductive layer 116 is used as an anode, the layer 4430-1 functions as an electron injection layer, the layer 4430-2 functions as an electron transport layer, the layer 4420-1 functions as a hole transport layer, and the layer 4420-2 functions as a hole injection layer. With such a layer structure, it is possible to efficiently inject carriers into the light-emitting layer 4411 and increase the efficiency of carrier recombination in the light-emitting layer 4411.

[0117] As shown in FIG. 17C, a configuration in which a plurality of light-emitting layers (light-emitting layers 4411, 4412, 4413) are provided between layer 4420 and layer 4430 is also a variation of the single structure.

[0118] 17D, a configuration in which a plurality of light-emitting units (EL layers 115a, 115b) are connected in series via an intermediate layer (charge generating layer) 4440 is referred to as a tandem structure. Although the configuration shown in FIG. 17D is referred to as a tandem structure in this specification, the present invention is not limited to this, and the tandem structure may also be referred to as a stack structure, for example. By using a tandem structure, a light-emitting element capable of emitting light with high brightness can be obtained.

[0119] 17C and 17D, the layer 4420 and the layer 4430 may have a laminated structure made up of two or more layers, as shown in FIG. 17B.

[0120] The light-emitting element can emit light in red, green, blue, cyan, magenta, yellow, or white, depending on the material of the EL layer 115. Furthermore, the color purity can be further improved by providing the light-emitting element with a microcavity structure.

[0121] A light-emitting element that emits white light preferably has a structure in which two or more light-emitting substances are contained in the light-emitting layer. To obtain white light emission, light-emitting substances are selected such that the respective emissions of the two or more light-emitting substances are in a complementary color relationship.

[0122] The light-emitting layer preferably contains two or more light-emitting materials that emit light of R (red), G (green), B (blue), Y (yellow), O (orange), etc. Alternatively, it is preferable that the light-emitting layer contains two or more light-emitting materials, and the light emitted by each of the light-emitting materials contains spectral components of two or more colors of R, G, and B.

[0123] Here, a specific configuration of the light emitting element will be described below.

[0124] The light-emitting element has at least a light-emitting layer. The light-emitting element may further have a layer containing a substance with high hole-injection properties, a substance with high hole-transport properties, a hole-blocking material, a substance with high electron-transport properties, an electron-blocking material, a substance with high electron-injection properties, a bipolar substance (a substance with high electron-transport properties and high hole-transport properties), or the like, in addition to the light-emitting layer.

[0125] The light-emitting device can be made of either a low-molecular-weight compound or a high-molecular-weight compound, and may contain an inorganic compound. The layers constituting the light-emitting device can be formed by a method such as vapor deposition (including vacuum vapor deposition), transfer, printing, inkjet printing, or coating.

[0126] For example, a light emitting device can include one or more of a hole injection layer, a hole transport layer, a hole blocking layer, an electron blocking layer, an electron transport layer, and an electron injection layer.

[0127] The hole injection layer is a layer that injects holes from the anode into the hole transport layer and contains a material with high hole injection properties, such as an aromatic amine compound and a composite material containing a hole transport material and an acceptor material (electron acceptor material).

[0128] The hole transport layer is a layer that transports holes injected from the anode by the hole injection layer to the light emitting layer. The hole transport layer is a layer that contains a hole transport material. The hole transport material is a material having a concentration of 1×10 -6 cm 2 A material having a hole mobility of 1 / Vs or more is preferred. Note that other materials can also be used as long as they have a higher hole transporting property than electron transporting property. As the hole transporting material, a material having a high hole transporting property, such as a π-electron-rich heteroaromatic compound (e.g., a carbazole derivative, a thiophene derivative, a furan derivative, etc.) or an aromatic amine (a compound having an aromatic amine skeleton), is preferred.

[0129] The electron transport layer is a layer that transports electrons injected from the cathode by the electron injection layer to the light emitting layer. The electron transport layer is a layer that contains an electron transporting material. The electron transporting material is a material having a molecular weight of 1×10 -6 cm 2 A substance having an electron mobility of 1 / Vs or more is preferred. Note that other substances can also be used as long as they have a higher electron transporting property than holes. Examples of electron-transporting materials that can be used include metal complexes having a quinoline skeleton, metal complexes having a benzoquinoline skeleton, metal complexes having an oxazole skeleton, and metal complexes having a thiazole skeleton, as well as oxadiazole derivatives, triazole derivatives, imidazole derivatives, oxazole derivatives, thiazole derivatives, phenanthroline derivatives, quinoline derivatives having a quinoline ligand, benzoquinoline derivatives, quinoxaline derivatives, dibenzoquinoxaline derivatives, pyridine derivatives, bipyridine derivatives, pyrimidine derivatives, and π-electron-deficient heteroaromatic compounds including nitrogen-containing heteroaromatic compounds.

[0130] The electron injection layer is a layer that injects electrons from the cathode to the electron transport layer and contains a material with high electron injection properties. Examples of the material with high electron injection properties include alkali metals, alkaline earth metals, and compounds thereof. Examples of the material with high electron injection properties include a composite material containing an electron transport material and a donor material (electron donor material).

[0131] Examples of the electron injection layer include lithium, cesium, lithium fluoride (LiF), cesium fluoride (CsF), calcium fluoride (CaF), 8-(quinolinolato)lithium (abbreviation: Liq), 2-(2-pyridyl)phenolatolithium (abbreviation: LiPP), 2-(2-pyridyl)-3-pyridinolatolithium (abbreviation: LiPPy), 4-phenyl-2-(2-pyridyl)phenolatolithium (abbreviation: LiPPP), and lithium oxide (LiO x ), alkali metals such as cesium carbonate, alkaline earth metals, or compounds thereof can be used.

[0132] Alternatively, the electron injection layer may be formed using a material having electron transport properties. For example, a compound having an unshared electron pair and an electron-deficient heteroaromatic ring may be used as the material having electron transport properties. Specifically, a compound having at least one of a pyridine ring, a diazine ring (pyrimidine ring, pyrazine ring, pyridazine ring), and a triazine ring may be used.

[0133] The lowest unoccupied molecular orbital (LUMO) of an organic compound having an unshared electron pair is preferably -3.6 eV or more and -2.3 eV or less. Generally, the highest occupied molecular orbital (HOMO) level and the LUMO level of an organic compound can be estimated by CV (cyclic voltammetry), photoelectron spectroscopy, optical absorption spectroscopy, inverse photoelectron spectroscopy, etc.

[0134] Examples of organic compounds with lone electron pairs include 4,7-diphenyl-1,10-phenanthroline (abbreviated as BPhen), 2,9-bis(naphthalen-2-yl)-4,7-diphenyl-1,10-phenanthroline (abbreviated as NBPhen), diquinoxalino[2,3-a:2',3'-c]phenazine (abbreviated as HATNA), and 2,4,6-tris[3'-(pyridin-3-yl)biphenyl-3-yl]-1,3,5-triazine (abbreviated as TmPPPyTz). NBPhen has a higher glass transition temperature (Tg) and better heat resistance than BPhen.

[0135] The light-emitting layer is a layer containing a light-emitting substance. The light-emitting layer can contain one or more light-emitting substances. As the light-emitting substance, a substance that emits light of a color such as blue, purple, blue-purple, green, yellow-green, yellow, orange, or red is appropriately used. Furthermore, a substance that emits near-infrared light can also be used as the light-emitting substance.

[0136] Examples of light-emitting materials include fluorescent materials, phosphorescent materials, TADF materials, and quantum dot materials.

[0137] 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.

[0138] Examples of phosphorescent materials include organometallic complexes (particularly iridium complexes) having a 4H-triazole skeleton, a 1H-triazole skeleton, an imidazole skeleton, a pyrimidine skeleton, a pyrazine skeleton, or a pyridine skeleton; organometallic complexes (particularly iridium complexes) having a phenylpyridine derivative having an electron-withdrawing group as a ligand; platinum complexes; and rare earth metal complexes.

[0139] The light-emitting layer may contain one or more organic compounds (host materials, assist materials, etc.) in addition to a light-emitting substance (guest material). One or more organic compounds may be a hole-transporting material or an electron-transporting material, or both. Alternatively, a bipolar material or a TADF material may be used as the one or more organic compounds.

[0140] The light-emitting layer preferably contains, for example, a phosphorescent material and a hole-transporting material and an electron-transporting material that are a combination that easily forms an exciplex. This configuration allows for efficient emission using Exciplex-Triplet Energy Transfer (ExTET), which is energy transfer from the exciplex to the light-emitting material (phosphorescent material). By selecting a combination that forms an exciplex that emits light that overlaps with the wavelength of the lowest-energy absorption band of the light-emitting material, the energy transfer becomes smooth, allowing for efficient emission. This configuration simultaneously enables high efficiency, low-voltage operation, and long life of the light-emitting device.

[0141] [Example of manufacturing method] An example of a method for manufacturing a display device according to one embodiment of the present invention will be described with reference to the drawings.

[0142] The thin films (insulating films, semiconductor films, conductive films, etc.) that make up the display device can be formed using methods such as sputtering, chemical vapor deposition (CVD), vacuum evaporation, pulsed laser deposition (PLD), and ALD. CVD methods include plasma enhanced chemical vapor deposition (PECVD) and thermal CVD. One type of thermal CVD method is metal organic chemical vapor deposition (MOCVD).

[0143] Furthermore, thin films (insulating films, semiconductor films, conductive films, etc.) that constitute the display device can be formed by methods such as spin coating, dipping, spray coating, inkjet, dispensing, screen printing, offset printing, doctor knife, slit coating, roll coating, curtain coating, and knife coating.

[0144] Furthermore, when processing the thin film that constitutes the display device, it can be processed using a photolithography method or the like. Alternatively, the thin film may be processed using a nanoimprint method, a sandblasting method, a lift-off method or the like. Furthermore, the island-shaped thin film may be directly formed by a film formation method using a shielding mask such as a metal mask.

[0145] There are two typical photolithography methods: one is to form a resist mask on the thin film to be processed, process the thin film by etching or the like, and then remove the resist mask; the other is to form a photosensitive thin film, and then process the thin film into the desired shape by exposure and development.

[0146] In the photolithography method, the light used for exposure can be, for example, i-line (wavelength 365 nm), g-line (wavelength 436 nm), h-line (wavelength 405 nm), or a mixture of these. In addition, ultraviolet light, KrF laser light, ArF laser light, etc. can also be used. Further, exposure may be performed by the immersion exposure technique. Also, extreme ultraviolet light (EUV: Extreme Ultra-violet) or X-rays may be used as the light for exposure. Instead of the light used for exposure, an electron beam can also be used. Using extreme ultraviolet light, X-rays or an electron beam is preferable because extremely fine processing becomes possible. When performing exposure by scanning a beam such as an electron beam, a photomask may not be used.

[0147] For the etching of the thin film, a dry etching method, a wet etching method, a sandblast method, etc. can be used.

[0148] An example of the manufacturing method of the display device shown in FIG. 1B will be described using FIGS. 5A to 5D and FIGS. 6A to 6D. By using the manufacturing method shown in FIGS. 5A to 5D and FIGS. 6A to 6D, the EL layer 115 and the conductive layer 116 can be processed without using a metal mask.

[0149] 〔Preparation of substrate 101〕 As the substrate 101, a substrate having heat resistance sufficient to withstand at least subsequent heat treatment can be used. When an insulating substrate is used as the substrate 101, examples include a glass substrate, a quartz substrate, a sapphire substrate, a ceramic substrate, etc. In addition, a single crystal semiconductor substrate made of silicon or silicon carbide, a polycrystalline semiconductor substrate, a compound semiconductor substrate such as silicon germanium, a semiconductor substrate such as an SOI substrate can be used.

[0150] In particular, it is preferable to use, as the substrate 101, a substrate on which a semiconductor circuit including semiconductor elements such as transistors is formed on the semiconductor substrate or insulating substrate. Such a semiconductor element may be formed using a semiconductor substrate such as a single crystal silicon substrate, or an oxide semiconductor film. The semiconductor circuit preferably constitutes, for example, a pixel circuit, a gate line driving circuit (gate driver), a source line driving circuit (source driver), or the like. In addition to the above, an arithmetic circuit, a memory circuit, or the like may also be formed.

[0151] In this embodiment, a substrate on which at least pixel circuits are formed is used as the substrate 101 .

[0152] [Deposition of insulating layer 121] An insulating layer 121 is formed on a substrate 101 (see FIG. 5A). The insulating layer 121 can be formed appropriately using the insulating material and film formation method described above.

[0153] 1C, the insulating layer 122 may be formed on the insulating layer 121. The insulating layer 122 may be formed using the insulating material and film formation method described above. By using a material with a low etching rate for the insulating layer 122, the insulating layer 122 can function as an etching stopper when the conductive layer 111, the EL layer 115, and the conductive layer 116 are formed.

[0154] [Formation of plug 131] An opening reaching the substrate 101 is formed in the insulating layer 121 at a position where the plug 131 is to be formed. The opening preferably reaches an electrode or wiring provided on the substrate 101. Subsequently, a conductive film is formed to fill the opening, and then a planarization process is performed to expose the upper surface of the insulating layer 121. This allows the plug 131 buried in the insulating layer 121 to be formed (see FIG. 5A).

[0155] [Formation of Conductive Layer 111] A conductive film is formed on the insulating layer 121 and the plug 131. The conductive film is processed into an island shape to form the conductive layer 111 (see FIG. 5B). The conductive layer 111 is electrically connected to the plug 131. Here, a recess may be formed in a region of the insulating layer 121 that does not overlap with the conductive layer 111.

[0156] [Formation of EL layer 115 and conductive layer 116] Next, the EL layer 115Bf and the conductive layer 116f of the light-emitting element 120B are formed in this order on the conductive layer 111 and the insulating layer 121. Next, a pattern is formed on the conductive layer 116f using a resist RES1 (see FIG. 5C). Here, the EL layer 115Bf is a layer that will become the EL layer 115B in a later process. The conductive layer 116f is a layer that will become the conductive layer 116 in a later process. The EL layer 115Bf and the EL layer 115Gf and EL layer 115Rf that will be formed later may be collectively referred to as the EL layer 115f.

[0157] The EL layer 115f includes at least a layer containing a light-emitting compound. Alternatively, the EL layer 115f may include an electron injection layer, an electron transport layer, a charge generation layer, a hole transport layer, and a hole injection layer. The EL layer 115f can be formed by a liquid phase method such as a vapor deposition method or an inkjet method.

[0158] The conductive layer 116f is formed to be transmissive and reflective to visible light. For example, a metal film or alloy film thin enough to transmit visible light can be used. Alternatively, a light-transmitting conductive film (for example, a metal oxide film) may be stacked on such a film.

[0159] Subsequently, etching is performed using the resist RES1 as a mask to form the conductive layer 116 and the EL layer 115B in this order, and then the resist RES1 is removed (see FIG. 5D).

[0160] When EL layer 115Bf is etched, chlorine and other substances used in the etching gas may adhere to the side surfaces of EL layer 115B. Furthermore, when resist RES1 is removed after conductive layer 116 and EL layer 115B are formed, or when conductive layer 116 and EL layer 115B are exposed to the atmosphere, impurities such as water or oxygen may be adsorbed to the side surfaces of EL layer 115B. This also applies to EL layer 115G and EL layer 115R, which will be described later.

[0161] Next, the EL layer 115Gf and conductive layer 116f of the light-emitting element 120G are formed in this order on the conductive layer 111, the insulating layer 121, and the conductive layer 116 of the light-emitting element 120B. Next, a pattern is formed on the conductive layer 116f using resist RES2 (see FIG. 6A). Here, the EL layer 115Gf is a layer that will become the EL layer 115G in a later process.

[0162] Subsequently, etching is performed using the resist RES2 as a mask to form the conductive layer 116 and the EL layer 115G in this order, and then the resist RES2 is removed.

[0163] Next, the EL layer 115Rf and conductive layer 116f of the light-emitting element 120R are formed in this order on the conductive layer 111, the insulating layer 121, the conductive layer 116 of the light-emitting element 120B, and the conductive layer 116 of the light-emitting element 120G. Next, a pattern is formed on the conductive layer 116f using resist RES3 (see FIG. 6B). Here, the EL layer 115Rf is a layer that will become the EL layer 115R in a later process.

[0164] Subsequently, etching is performed using the resist RES3 as a mask to form the conductive layer 116 and the EL layer 115R in this order, and then the resist RES3 is removed (see FIG. 6C).

[0165] In this embodiment, the EL layer 115 and the conductive layer 116 are formed after the conductive layer 111 is formed, but the present invention is not limited to this. For example, the conductive layer 111, the EL layer 115f, and the conductive layer 116f may be formed in this order and processed into an island shape all at once to form the conductive layer 111, the EL layer 115, and the conductive layer 116.

[0166] In addition, in the present embodiment, the EL layer 115f and the conductive layer 116f are formed continuously in each light-emitting element 120, but the present invention is not limited to this. The conductive layer 116 may be formed after forming only the EL layer 115 using a method similar to that shown in Figures 5C to 6C. In this case, the conductive layer 116 can be processed so that it is continuous and not separated among the light-emitting elements 120B, 120G, and 120R.

[0167] 5C to 6C , after forming a part of the EL layer 115, the other part of the EL layer 115 and the conductive layer 116 may be formed. For example, a configuration may be adopted in which the electron injection layer of the EL layer 115 and the conductive layer 116 are formed later. In this case, the electron injection layer of the EL layer 115 and the conductive layer 116 can be processed so as to be continuous and not separated among the light-emitting elements 120B, 120G, and 120R.

[0168] Here, if resist is formed directly on EL layer 115f, the solvent in the resist may deteriorate EL layer 115f. Therefore, it is preferable to provide an inorganic film functioning as a sacrificial layer between EL layer 115f and the resist to prevent the resist from coming into direct contact with EL layer 115f. For example, when EL layer 115 has the structure shown in FIG. 17B, an inorganic film functioning as a sacrificial layer may be provided on layer 4420-1 functioning as an electron transport layer, and resist may be provided thereon, and layers 4430-1, 4430-2, light-emitting layer 4411, and 4420-1 may be etched.

[0169] [Deposition of insulating layer 124] Subsequently, the insulating layer 124 is formed on the insulating layer 121 and the conductive layer 116 (see FIG. 6D). The insulating layer 124 can be formed appropriately using the insulating material and film formation method described above. The temperature for forming the insulating layer 124 is preferably within a range in which the EL layer 115 does not deteriorate, and may be, for example, from room temperature to 100° C.

[0170] Here, the process of forming the insulating layer 124 will be described with reference to FIGS. 7A to 7C, which are enlarged views corresponding to the region A in FIG. 6D.

[0171] First, a layer 124a is formed to cover the insulating layer 121, the conductive layer 111, the EL layer 115, and the conductive layer 116 (see FIG. 7A). The layer 124a can be formed using any of the insulating materials and deposition methods described above. For example, aluminum oxide may be deposited by sputtering. Here, it is preferable to reduce the oxygen content in the deposition gas or to not include oxygen in the deposition gas. This increases oxygen vacancies in the layer 124a, thereby improving the ability of the layer 124a to capture or fix impurities such as water or oxygen.

[0172] Next, a layer 124b is formed to cover the layer 124a (see FIG. 7B). The layer 124b can be formed using the insulating material and film formation method described above. For example, silicon nitride may be formed by sputtering.

[0173] Next, a layer 124c is formed to cover the layer 124b (see FIG. 7C). The layer 124c can be formed using the insulating material and film formation method described above. For example, aluminum oxide can be formed using the ALD method.

[0174] As described above, during the etching process, impurities such as water or oxygen, or impurities such as chlorine used in the etching, may adhere to the side surfaces of light-emitting element 120, particularly EL layers 115B, 115G, and 115R. By providing insulating layer 124 as described above, these impurities can be captured or fixed by layer 124a. This prevents the impurities from forming a different layer on the side surfaces of EL layer 115, thereby improving the reliability of light-emitting element 120.

[0175] In this manner, the display device 100 having the light emitting elements 120R, 120G, and 120B can be formed.

[0176] [Configuration example 2] An example of a display device including a transistor will be described below.

[0177] [Configuration Example 2-1] FIG. 8A is a schematic cross-sectional view of the display device 200A.

[0178] The display device 200A includes a substrate 201, a light emitting element 120R, a light emitting element 120G, a light emitting element 120B, a capacitor element 240, a transistor 210, and the like.

[0179] The laminated structure from the substrate 201 to the capacitive element 240 corresponds to the substrate 101 in the first configuration example.

[0180] The transistor 210 is a transistor in which a channel formation region is formed in a substrate 201. The substrate 201 can be, for example, a semiconductor substrate such as a single crystal silicon substrate. The transistor 210 includes a part of the substrate 201, a conductive layer 211, a low-resistance region 212, an insulating layer 213, an insulating layer 214, and the like. The conductive layer 211 functions as a gate electrode. The insulating layer 213 is located between the substrate 201 and the conductive layer 211 and functions as a gate insulating layer. The low-resistance region 212 is a region in which the substrate 201 is doped with impurities and functions as either a source or a drain. The insulating layer 214 is provided to cover a side surface of the conductive layer 211 and functions as an insulating layer.

[0181] In addition, an element isolation layer 215 is provided between two adjacent transistors 210 so as to be embedded in the substrate 201 .

[0182] In addition, an insulating layer 261 is provided to cover the transistor 210 , and a capacitor 240 is provided over the insulating layer 261 .

[0183] The capacitor 240 includes a conductive layer 241, a conductive layer 242, and an insulating layer 243 located therebetween. The conductive layer 241 functions as one electrode of the capacitor 240, the conductive layer 242 functions as the other electrode of the capacitor 240, and the insulating layer 243 functions as a dielectric of the capacitor 240.

[0184] The conductive layer 241 is provided over the insulating layer 261 and is electrically connected to one of the source and drain of the transistor 210 by a plug 271 embedded in the insulating layer 261. The insulating layer 243 is provided to cover the conductive layer 241. The conductive layer 242 is provided in a region overlapping with the conductive layer 241 with the insulating layer 243 interposed therebetween.

[0185] An insulating layer 121 is provided to cover the capacitive element 240, and the light emitting element 120R, the light emitting element 120G, the light emitting element 120B, etc. are provided on the insulating layer 121. Here, an example is shown in which the configuration illustrated in FIG. 1A is used as the configuration of the light emitting element 120R, the light emitting element 120G, the light emitting element 120B, etc., but the present invention is not limited to this, and various configurations exemplified above can be applied.

[0186] In the display device 200A, an insulating layer 124, an insulating layer 162, and an insulating layer 163 are provided in this order to cover the conductive layer 116 of the light-emitting element 120. These three insulating layers function as protective layers to prevent impurities such as water from diffusing into the light-emitting element 120. The insulating layer 163 is preferably made of an inorganic insulating film with low moisture permeability, such as a silicon oxide film, a silicon nitride film, or an aluminum oxide film. The insulating layer 162 can be made of an organic insulating film with high light transmissivity. Using an organic insulating film for the insulating layer 162 reduces the influence of unevenness below the insulating layer 162, thereby smoothing the surface on which the insulating layer 163 is formed. This reduces the likelihood of defects such as pinholes occurring in the insulating layer 163, thereby further improving the moisture permeability of the protective layer. The configuration of the protective layer covering the light-emitting element 120 is not limited to this, and it may be a single-layer structure, a two-layer structure, or a stacked structure of four or more layers.

[0187] By providing the insulating layer 124, it is possible to prevent impurities such as water or oxygen from diffusing into the light emitting element 120, as shown in the above configuration example.

[0188] The display device 200A has a substrate 202 on the viewing side. The substrate 202 and the substrate 201 are bonded together by a light-transmitting adhesive layer 164. The substrate 202 may be a light-transmitting substrate such as a glass substrate, a quartz substrate, a sapphire substrate, or a plastic substrate.

[0189] Furthermore, when using white-emitting light-emitting elements such as those shown in FIGS. 4A and 4B, it is preferable to provide colored layers 165R, 165G, and 165B as shown in FIG. 8B. On the insulating layer 163, the colored layer 165R overlaps the light-emitting element 120R, the colored layer 165G overlaps the light-emitting element 120G, and the colored layer 165B overlaps the light-emitting element 120B. For example, the colored layer 165R transmits red light, the colored layer 165G transmits green light, and the colored layer 165B transmits blue light. This improves the color purity of the light from each light-emitting element, resulting in a display device with higher display quality. Furthermore, by forming each colored layer on the insulating layer 163, it is easier to align each light-emitting unit with each colored layer than when the colored layers are formed on the substrate 202 (described later), resulting in a display device with extremely high resolution. However, without being limited to the above, even when the light emitting element is divided into red light emitting, green light emitting, and blue light emitting elements, the colored layer 165R, the colored layer 165G, and the colored layer 165B may be provided.

[0190] With this configuration, a display device with extremely high definition and high display quality can be realized.

[0191] [Configuration Example 2-2] 9 is a schematic cross-sectional view of the display device 200 B. The display device 200 B differs from the display device 200 A mainly in that the transistor configuration is different.

[0192] The transistor 220 is a transistor in which a metal oxide (also referred to as an oxide semiconductor) is used for a semiconductor layer in which a channel is formed.

[0193] The transistor 220 includes a semiconductor layer 221, an insulating layer 223, a conductive layer 224, a pair of conductive layers 225, an insulating layer 226, a conductive layer 227, and the like.

[0194] The substrate 201 on which the transistor 220 is provided can be the insulating substrate or semiconductor substrate described above.

[0195] An insulating layer 232 is provided over the substrate 201. The insulating layer 232 functions as a barrier layer that prevents impurities such as water or hydrogen from diffusing from the substrate 201 to the transistor 220 and prevents oxygen from being released from the semiconductor layer 221 toward the insulating layer 232. The insulating layer 232 can be, for example, a film through which hydrogen or oxygen is less likely to diffuse than a silicon oxide film, such as an aluminum oxide film, a hafnium oxide film, or a silicon nitride film.

[0196] A conductive layer 227 is provided over the insulating layer 232, and an insulating layer 226 is provided to cover the conductive layer 227. The conductive layer 227 functions as a first gate electrode of the transistor 220, and part of the insulating layer 226 functions as a first gate insulating layer. An oxide insulating film such as a silicon oxide film is preferably used for at least a portion of the insulating layer 226 that is in contact with the semiconductor layer 221. The top surface of the insulating layer 226 is preferably planarized.

[0197] The semiconductor layer 221 is provided over the insulating layer 226. The semiconductor layer 221 preferably includes a metal oxide (also referred to as an oxide semiconductor) film having semiconductor characteristics. Materials that can be suitably used for the semiconductor layer 221 will be described in detail later.

[0198] The pair of conductive layers 225 is provided over and in contact with the semiconductor layer 221 and functions as a source electrode and a drain electrode.

[0199] An insulating layer 228 is provided to cover top surfaces and side surfaces of the pair of conductive layers 225 and side surfaces of the semiconductor layer 221, and an insulating layer 261b is provided over the insulating layer 228. The insulating layer 228 functions as a barrier layer that prevents impurities such as water or hydrogen from diffusing from the insulating layer 261b or the like to the semiconductor layer 221 and prevents oxygen from being released from the semiconductor layer 221. The insulating layer 228 can be an insulating film similar to the insulating layer 232.

[0200] An opening is provided in the insulating layer 228 and the insulating layer 261b, reaching the semiconductor layer 221. An insulating layer 223 and a conductive layer 224 are buried inside the opening and are in contact with the side surfaces of the insulating layer 261b, the insulating layer 228, and the conductive layer 225, as well as the upper surface of the semiconductor layer 221. The conductive layer 224 functions as a second gate electrode, and the insulating layer 223 functions as a second gate insulating layer.

[0201] The upper surfaces of the conductive layer 224, the insulating layer 223, and the insulating layer 261b are flattened so that they are at roughly the same height, and insulating layers 229 and 261a are provided to cover them.

[0202] The insulating layers 261a and 261b function as interlayer insulating layers. The insulating layer 229 functions as a barrier layer that prevents impurities such as water or hydrogen from diffusing from the insulating layer 261a or the like to the transistor 220. The insulating layer 229 can be formed using an insulating film similar to the insulating layer 228 and the insulating layer 232.

[0203] A plug 271 electrically connected to one of the pair of conductive layers 225 is provided so as to be embedded in the insulating layer 261a, the insulating layer 229, and the insulating layer 261b. Here, the plug 271 preferably has a conductive layer 271a covering the side surfaces of the openings of the insulating layer 261a, the insulating layer 261b, the insulating layer 229, and the insulating layer 228 and a part of the upper surface of the conductive layer 225, and a conductive layer 271b in contact with the upper surface of the conductive layer 271a. In this case, the conductive layer 271a is preferably made of a conductive material through which hydrogen and oxygen do not easily diffuse.

[0204] Furthermore, as described in the above embodiment, providing the insulating layer 122 or the insulating layer 124 can suppress diffusion of impurities such as water or hydrogen into the transistor 220. As a result, the electrical characteristics and reliability of the transistor 220 can be improved.

[0205] [Configuration Example 2-3] 10 is a schematic cross-sectional view of a display device 200C. The display device 200C has a stacked configuration of a transistor 210 having a channel formed in a substrate 201 and a transistor 220 having a channel formed in a semiconductor layer containing a metal oxide.

[0206] An insulating layer 261 is provided to cover the transistor 210, and a conductive layer 251 is provided over the insulating layer 261. An insulating layer 262 is provided to cover the conductive layer 251, and a conductive layer 252 is provided over the insulating layer 262. The conductive layer 251 and the conductive layer 252 each function as a wiring. An insulating layer 263 and an insulating layer 232 are provided to cover the conductive layer 252, and a transistor 220 is provided over the insulating layer 232. An insulating layer 265 is provided to cover the transistor 220, and a capacitor 240 is provided over the insulating layer 265. The capacitor 240 and the transistor 220 are electrically connected to each other by a plug 274.

[0207] The transistor 220 can be used as a transistor included in a pixel circuit. The transistor 210 can be used as a transistor included in a pixel circuit or a driver circuit (gate line driver circuit, source line driver circuit) for driving the pixel circuit. The transistors 210 and 220 can be used as transistors included in various circuits such as an arithmetic circuit or a memory circuit.

[0208] By using this configuration, not only pixel circuits but also driving circuits etc. can be formed directly below the light-emitting units, making it possible to make the display device smaller than when driving circuits are provided around the periphery of the display area.

[0209] [Configuration Example 2-4] 11 is a schematic cross-sectional view of a display device 200D. The display device 200D differs from the display device 200C described above mainly in that two transistors using an oxide semiconductor are stacked.

[0210] The display device 200D includes a transistor 230 between the transistor 210 and the transistor 220. The transistor 230 has a similar structure to the transistor 220 except that the transistor 230 does not include a first gate electrode. Note that the transistor 230 may include a first gate electrode.

[0211] An insulating layer 263 and an insulating layer 231 are provided to cover the conductive layer 252, and a transistor 230 is provided over the insulating layer 231. The transistor 230 and the conductive layer 252 are electrically connected to each other through a plug 273, the conductive layer 253, and a plug 272. Furthermore, an insulating layer 264 and an insulating layer 232 are provided to cover the conductive layer 253, and a transistor 220 is provided over the insulating layer 232.

[0212] For example, the transistor 220 functions as a transistor for controlling a current flowing through the light-emitting element 120. The transistor 230 functions as a selection transistor for controlling the selection state of the pixel. The transistor 210 functions as a transistor that constitutes a driver circuit for driving the pixel.

[0213] In this way, by stacking three or more layers in which transistors are formed, the area occupied by a pixel can be further reduced, and a high-definition display device can be realized.

[0214] Components such as transistors that can be applied to a display device will be described below.

[0215] [Transistor] The transistor includes a conductive layer functioning as a gate electrode, a semiconductor layer, a conductive layer functioning as a source electrode, a conductive layer functioning as a drain electrode, and an insulating layer functioning as a gate insulating layer.

[0216] Note that the structure of a transistor included in a display device of one embodiment of the present invention is not particularly limited. For example, a planar transistor, a staggered transistor, or an inverted staggered transistor may be used. Furthermore, a top-gate or bottom-gate transistor structure may be used. Alternatively, gate electrodes may be provided above and below a channel.

[0217] The crystallinity of a semiconductor material used for a transistor is not particularly limited, and any of an amorphous semiconductor and a crystalline semiconductor (a microcrystalline semiconductor, a polycrystalline semiconductor, a single crystal semiconductor, or a semiconductor having a crystalline region in part) may be used. The use of a crystalline semiconductor is preferable because it can suppress deterioration of transistor characteristics.

[0218] In the following, a transistor using a metal oxide film as a semiconductor layer in which a channel is formed will be described in particular.

[0219] The semiconductor material used for the transistor can be a metal oxide having an energy gap of 2 eV or more, preferably 2.5 eV or more, more preferably 3 eV or more, typically a metal oxide containing indium, such as CAC-OS (described later).

[0220] A transistor using a metal oxide, which has a wider band gap and a lower carrier density than silicon, can hold charge accumulated in a capacitor connected in series with the transistor for a long period of time due to its low off-state current.

[0221] The semiconductor layer may be, for example, a film represented by an In-M-Zn oxide containing indium, zinc, and M (M is a metal such as aluminum, titanium, gallium, germanium, yttrium, zirconium, lanthanum, cerium, tin, neodymium, or hafnium).

[0222] When the metal oxide constituting the semiconductor layer is an In-M-Zn oxide, the atomic ratio of the metal elements in the sputtering target used to deposit the In-M-Zn oxide preferably satisfies In≧M and Zn≧M. Preferred atomic ratios of the metal elements in such sputtering targets are In:M:Zn=1:1:1, In:M:Zn=1:1:1.2, In:M:Zn=3:1:2, In:M:Zn=4:2:3, In:M:Zn=4:2:4.1, In:M:Zn=5:1:6, In:M:Zn=5:1:7, In:M:Zn=5:1:8, and the like. The atomic ratios of the deposited semiconductor layer each vary within ±40% of the atomic ratio of the metal elements contained in the sputtering target.

[0223] The semiconductor layer is a metal oxide film with a low carrier density. For example, the semiconductor layer is a metal oxide film with a carrier density of 1×10 17 / cm 3 Less than 1 × 10 15 / cm 3 or less, more preferably 1 × 10 13 / cm 3 Less than or equal to 1×10 11 / cm 3 or less, more preferably 1 × 10 10 / cm 3 Less than 1 x 10 -9 / cm 3 A metal oxide having a carrier density of 1000 or more can be used. Such a metal oxide is called a high-purity intrinsic or substantially high-purity intrinsic metal oxide. The oxide semiconductor can be said to be a metal oxide having a low density of defect states and stable characteristics.

[0224] Note that an oxide semiconductor having an appropriate composition may be used depending on the semiconductor characteristics and electrical characteristics (field-effect mobility, threshold voltage, etc.) of the transistor that are required. In order to obtain the semiconductor characteristics of the transistor that are required, it is preferable to set the carrier density, impurity concentration, defect density, atomic ratio of metal element to oxygen, interatomic distance, density, and the like of the semiconductor layer to be appropriate.

[0225] If the metal oxide constituting the semiconductor layer contains silicon or carbon, which is one of the group 14 elements, oxygen vacancies increase in the semiconductor layer, causing it to become n-type. For this reason, the concentration of silicon or carbon in the semiconductor layer (concentration obtained by secondary ion mass spectrometry) is set to 2×10 18 atoms / cm 3 Less than or equal to 2 x 10 17 atoms / cm 3 The following applies.

[0226] In addition, when alkali metals and alkaline earth metals bond with metal oxides, they may generate carriers, which may increase the off-state current of a transistor. Therefore, the concentration of alkali metals or alkaline earth metals in a semiconductor layer obtained by secondary ion mass spectrometry is set to 1×10 18 atoms / cm 3 Less than or equal to 2 x 10 16 atoms / cm 3 Do the following:

[0227] Furthermore, if the metal oxide that makes up the semiconductor layer contains nitrogen, electrons that act as carriers are generated, increasing the carrier density and making the transistor more likely to be n-type. As a result, transistors that use metal oxides that contain nitrogen tend to have normally-on characteristics. For this reason, the nitrogen concentration in the semiconductor layer obtained by secondary ion mass spectrometry is 5×10 18 atoms / cm 3 It is preferable to do the following:

[0228] Furthermore, hydrogen contained in an oxide semiconductor may react with oxygen bonded to a metal atom to form water, which may form an oxygen vacancy. When hydrogen enters the oxygen vacancy, electrons serving as carriers may be generated. Furthermore, some of the hydrogen may bond with oxygen bonded to a metal atom to generate electrons serving as carriers. Therefore, a transistor using an oxide semiconductor containing hydrogen is likely to have normally-on characteristics. For this reason, it is preferable to reduce the amount of hydrogen in the channel formation region of the oxide semiconductor as much as possible. Specifically, the hydrogen concentration in the channel formation region of the oxide semiconductor obtained by secondary ion mass spectrometry is 1×10 20 atoms / cm 3 Less than 5 x 10 19 atoms / cm 3 less than 1×10 19 atoms / cm 3 less than 5 × 10 18 atoms / cm 3 less than 1×10 18 atoms / cm 3 Make it less than.

[0229] When an oxide semiconductor with sufficiently reduced impurities is used for a channel formation region of a transistor, stable electrical characteristics and reliability can be obtained.

[0230] Oxide semiconductors are classified into single-crystal oxide semiconductors and non-single-crystal oxide semiconductors, which include c-axis-aligned crystalline oxide semiconductors (CAAC-OS), polycrystalline oxide semiconductors, nanocrystalline oxide semiconductors (nc-OS), amorphous-like oxide semiconductors (a-like OS), and amorphous oxide semiconductors.

[0231] In addition, CAC-OS (cloud-aligned composite oxide semiconductor) may be used for the semiconductor layer of the transistor disclosed in one aspect of the present invention.

[0232] Note that the semiconductor layer of the transistor disclosed in one aspect of the present invention can preferably use the above-described non-single crystal oxide semiconductor. Further, as the non-single crystal oxide semiconductor, nc-OS or CAAC-OS can be preferably used.

[0233] Note that in one aspect of the present invention, it is preferable to use CAC-OS as the semiconductor layer of the transistor. By using CAC-OS, high electrical characteristics or high reliability can be imparted to the transistor.

[0234] Note that the semiconductor layer may be a mixed film having two or more of the regions of CAAC-OS, polycrystalline oxide semiconductor, nc-OS, pseudo-amorphous oxide semiconductor, and amorphous oxide semiconductor. The mixed film may have, for example, a single-layer structure or a laminated structure including any two or more of the above-described regions.

[0235] <Configuration of CAC-OS> Hereinafter, the configuration of CAC-OS that can be used for the transistor disclosed in one aspect of the present invention will be described.

[0236] CAC-OS is, for example, a configuration of a material in which elements constituting a metal oxide are unevenly distributed in a size of 0.5 nm or more and 10 nm or less, preferably 1 nm or more and 2 nm or less, or in the vicinity thereof. Hereinafter, in the metal oxide, one or more metal elements are unevenly distributed, and a region having the metal element is in a state of being mixed in a size of 0.5 nm or more and 10 nm or less, preferably 1 nm or more and 2 nm or less, or in the vicinity thereof, which is also referred to as a mosaic state or a patch state.

[0237] The metal oxide preferably contains at least indium, particularly indium and zinc, and may further contain one or more elements selected from aluminum, gallium, yttrium, copper, vanadium, beryllium, boron, silicon, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, magnesium, and the like.

[0238] For example, CAC-OS in In-Ga-Zn oxide (In-Ga-Zn oxide among CAC-OS may be particularly referred to as CAC-IGZO) is an indium oxide (hereinafter referred to as InO X1 (X1 is a real number greater than 0) or indium zinc oxide (hereinafter referred to as In X2 Zn Y2 O Z2 (X2, Y2, and Z2 are real numbers greater than 0) and gallium oxide (hereinafter referred to as GaO X3 (X3 is a real number greater than 0) or gallium zinc oxide (Ga X4 Zn Y4 O Z4 (X4, Y4, and Z4 are real numbers greater than 0.) The material is separated into mosaic shapes, and the mosaic InO X1 , or In X2 Zn Y2 O Z2 However, the structure is such that the particles are uniformly distributed in the film (hereinafter also referred to as a cloud-like structure).

[0239] In other words, CAC-OS is X3 The region where In is the main component and X2 Zn Y2 O Z2 , or InO X1 In this specification, for example, when the atomic ratio of In to element M in the first region is greater than the atomic ratio of In to element M in the second region, the first region is said to have a higher In concentration than the second region.

[0240] IGZO is a common name and may refer to a compound of In, Ga, Zn, and O. A typical example is InGaO3(ZnO). m1 (m1 is a natural number, but m1 is not 0.) or In (1+x0) Ga (1-x0) O3(ZnO) m0 (-1≦x0≦1, m0 is an arbitrary number).

[0241] The crystalline compound has a single crystal structure, a polycrystalline structure, or a CAAC structure, where multiple IGZO nanocrystals are aligned along the c-axis and connected without being aligned in the ab-plane.

[0242] On the other hand, CAC-OS refers to a metal oxide material structure. CAC-OS is a material structure containing In, Ga, Zn, and O, in which some regions observed as nanoparticles mainly composed of Ga and some regions observed as nanoparticles mainly composed of In are randomly dispersed in a mosaic pattern. Therefore, in CAC-OS, the crystal structure is a secondary element.

[0243] Note that CAC-OS does not include a stacked structure of two or more films with different compositions, such as a two-layer structure consisting of a film mainly containing In and a film mainly containing Ga.

[0244] In addition, GaO X3 The region where In is the main component and X2 Zn Y2 O Z2 , or InO X1 In some cases, a clear boundary between the region where the main component is the chromatic aberration and the region where the chromatic aberration is the main component may not be observed.

[0245] When one or more elements selected from aluminum, yttrium, copper, vanadium, beryllium, boron, silicon, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, and magnesium are contained instead of gallium, the CAC-OS has a structure in which some regions observed to be nanoparticles containing the metal element as the main component and some regions observed to be nanoparticles containing In as the main component are randomly dispersed in a mosaic pattern.

[0246] The CAC-OS can be formed, for example, by a sputtering method without heating the substrate. When the CAC-OS is formed by a sputtering method, one or more of an inert gas (typically argon), oxygen gas, and nitrogen gas may be used as the deposition gas. The lower the flow rate of oxygen gas relative to the total flow rate of deposition gas during deposition, the better. For example, the flow rate of oxygen gas is preferably 0% or more and less than 30%, and more preferably 0% or more and 10% or less.

[0247] CAC-OS has the characteristic that no clear peaks are observed when measured using the θ / 2θ scan by the out-of-plane X-ray diffraction (XRD) method, which indicates that the orientation of the measured region in the ab-plane direction and the c-axis direction is not observed.

[0248] In addition, an electron beam diffraction pattern of CAC-OS obtained by irradiating it with an electron beam (also called a nanobeam electron beam) with a probe diameter of 1 nm shows a bright ring-shaped region with multiple bright spots within the ring-shaped region. Therefore, the electron beam diffraction pattern indicates that the CAC-OS has a nanocrystal (nc) structure that does not have orientation in the planar and cross-sectional directions.

[0249] For example, in the case of CAC-OS made of In-Ga-Zn oxide, EDX mapping obtained using EDX (Energy Dispersive X-ray spectroscopy) revealed that GaO X3 The region where In is the main component and X2 Zn Y2 O Z2 , or InO X1 It can be seen that the region where the main component is the crystalline silicon is unevenly distributed and mixed.

[0250] CAC-OS has a different structure from IGZO compounds, in which metal elements are uniformly distributed, and has different properties from IGZO compounds. X3 The region where In is the main component. X2 Zn Y2 O Z2 , or InO X1 The structure is such that the regions are separated into a mosaic of regions each containing one of the elements as the main component and a region each containing one of the elements as the main component.

[0251] Here, In X2 Zn Y2 O Z2 , or InO X1 The region where is the main component is GaO X3 This region has higher conductivity than the region where In is the main component. X2 Zn Y2 O Z2 , or InO X1 When carriers flow through the region where In is the main component, the conductivity of the metal oxide is exhibited. X2 Zn Y2 O Z2 , or InO X1 The cloud-like distribution of regions containing the main component in the metal oxide allows for high field-effect mobility (μ).

[0252] On the other hand, GaO X3 The region where the main components are In X2 Zn Y2 O Z2 , or InOX1 This region has higher insulating properties than the region where GaO is the main component. X3 By distributing regions in which the main components are such as these in the metal oxide, leakage current can be suppressed and good switching operation can be achieved.

[0253] Therefore, when CAC-OS is used in a semiconductor device, GaO X3 Insulation due to X2 Zn Y2 O Z2 , or InO X1 The conductivity due to the gate insulating layer and the gate insulating layer work in a complementary manner, resulting in a high on-state current (I on ), and high field-effect mobility (μ) can be achieved.

[0254] Furthermore, semiconductor elements using CAC-OS have high reliability, making them ideal for a variety of semiconductor devices, including displays.

[0255] Furthermore, since a transistor having a CAC-OS semiconductor layer has high field-effect mobility and high driving capability, a display device with a narrow frame width (also referred to as a narrow frame) can be provided by using the transistor in a driver circuit, typically a scan line driver circuit that generates gate signals.Furthermore, a display device with a small number of wirings connected to the display device can be provided by using the transistor in a signal line driver circuit (especially a demultiplexer connected to an output terminal of a shift register in the signal line driver circuit).

[0256] Furthermore, unlike transistors using low-temperature polysilicon, transistors having a CAC-OS semiconductor layer do not require a laser crystallization process. This allows for reduced manufacturing costs even for display devices using large-area substrates. Furthermore, in large-sized display devices with high resolutions such as ultra-high definition (4K resolution, 4K2K, 4K) and super high definition (8K resolution, 8K4K, 8K), using transistors having a CAC-OS semiconductor layer in the driver circuits and display units enables writing in a short time and reduces display defects, which is preferable.

[0257] Alternatively, silicon may be used as a semiconductor in which a channel of a transistor is formed. Although amorphous silicon may be used as the silicon, it is preferable to use silicon having crystallinity. For example, it is preferable to use microcrystalline silicon, polycrystalline silicon, single crystal silicon, or the like. In particular, polycrystalline silicon can be formed at a lower temperature than single crystal silicon, and has higher field-effect mobility and higher reliability than amorphous silicon.

[0258] [Conductive Layer] Materials that can be used for conductive layers such as the gate, source, and drain of a transistor, as well as various wirings and electrodes constituting a display device, include metals such as aluminum, titanium, chromium, nickel, copper, yttrium, zirconium, molybdenum, silver, tantalum, and tungsten, or alloys containing these metals as their main components. Films containing these materials can be used as single layers or multilayer structures. Examples include a single-layer structure of an aluminum film containing silicon, a bilayer structure in which an aluminum film is stacked on a titanium film, a bilayer structure in which an aluminum film is stacked on a tungsten film, a bilayer structure in which a copper film is stacked on a copper-magnesium-aluminum alloy film, a bilayer structure in which a copper film is stacked on a titanium film, a bilayer structure in which a copper film is stacked on a tungsten film, a three-layer structure in which a titanium film or titanium nitride film is stacked on an aluminum film or copper film, and a three-layer structure in which a titanium film or titanium nitride film is further stacked on top of that, and a three-layer structure in which a molybdenum film or molybdenum nitride film is stacked on an aluminum film or copper film, and a molybdenum film or molybdenum nitride film is further stacked on top of that. Alternatively, oxides such as indium oxide, tin oxide, or zinc oxide may be used. Furthermore, copper containing manganese is preferably used because it improves the controllability of the shape by etching.

[0259] [Insulating layer] Examples of insulating materials that can be used for each insulating layer include resins such as acrylic resin and epoxy resin, resins having siloxane bonds such as silicone, as well as inorganic insulating materials such as silicon oxide, silicon oxynitride, silicon nitride oxide, silicon nitride, and aluminum oxide.

[0260] In this specification, an oxynitride refers to a material whose composition contains more oxygen than nitrogen, and a nitride oxide refers to a material whose composition contains more nitrogen than oxygen. For example, silicon oxynitride refers to a material whose composition contains more oxygen than nitrogen, and silicon nitride oxide refers to a material whose composition contains more nitrogen than oxygen.

[0261] Furthermore, the light emitting element is preferably provided between a pair of insulating films with low water permeability, which can prevent impurities such as water from entering the light emitting element and prevent a decrease in the reliability of the device.

[0262] Examples of the insulating film with low water permeability include a film containing nitrogen and silicon, such as a silicon nitride film or a silicon nitride oxide film, or a film containing nitrogen and aluminum, such as an aluminum nitride film. Alternatively, a silicon oxide film, a silicon oxynitride film, an aluminum oxide film, or the like may be used.

[0263] For example, the water vapor permeation rate of a low-permeability insulating film is 1×10 -5 [g / (m 2 ·day)] or less, preferably 1 × 10 -6 [g / (m 2 ·day)] or less, more preferably 1 × 10 -7 [g / (m 2 ·day)] or less, more preferably 1 × 10 -8 [g / (m 2 ·day)] or less.

[0264] [Display module configuration example] A structural example of a display module including a display device of one embodiment of the present invention will be described below.

[0265] 12A is a perspective schematic diagram of a display module 280. The display module 280 includes a display device 200 and an FPC 290. As the display device 200, any of the display devices exemplified in the above configuration example 2 (display device 200A to display device 200D) can be applied.

[0266] The display module 280 has a substrate 201 and a substrate 202. It also has a display unit 281 on the substrate 202 side. The display unit 281 is an area that displays an image in the display module 280, and is an area where light from each pixel provided in a pixel unit 284 (described later) can be viewed. The display module 280 may also have a source driver IC 290b.

[0267] 12B is a perspective view showing a schematic configuration of the substrate 201 side. The substrate 201 has a configuration in which a circuit portion 282, a pixel circuit portion 283 on the circuit portion 282, and a pixel portion 284 on the pixel circuit portion 283 are stacked. The substrate 201 also has a terminal portion 285 for connecting to an FPC 290 in a portion of the substrate 201 that does not overlap with the pixel portion 284. The terminal portion 285 and the circuit portion 282 are electrically connected by a wiring portion 286 consisting of a plurality of wirings.

[0268] The pixel section 284 has a plurality of periodically arranged pixels 284a. An enlarged view of one pixel 284a is shown on the right side of Fig. 12B. The pixel 284a has a light emitting element 120R, a light emitting element 120G, and a light emitting element 120B.

[0269] The pixel circuit section 283 has a plurality of pixel circuits 283a arranged periodically. The plurality of pixels 284a and the plurality of pixel circuits 283a may be arranged in a stripe arrangement as shown in Fig. 12B. Note that the arrangement is not limited to a stripe arrangement, and the plurality of pixels 284a and the plurality of pixel circuits 283a may also be arranged in a delta arrangement.

[0270] One pixel circuit 283a is a circuit that controls the light emission of three light-emitting elements included in one pixel 284a. One pixel circuit 283a may be configured to have three circuits that control the light emission of one light-emitting element. For example, the pixel circuit 283a may be configured to have at least one selection transistor, one current control transistor (drive transistor), and a capacitance element for each light-emitting element. In this case, a gate signal is input to the gate of the selection transistor, and a source signal is input to either the source or the drain. This realizes an active matrix display device.

[0271] The circuit portion 282 includes a circuit for driving each pixel circuit 283a of the pixel circuit portion 283. For example, the circuit portion 282 preferably includes a gate line driver circuit, a source line driver circuit, etc. In addition, the circuit portion 282 may include an arithmetic circuit, a memory circuit, a power supply circuit, etc.

[0272] The FPC 290 functions as wiring for supplying a video signal, a power supply potential, or the like from the outside to the circuit section 282. An IC may also be mounted on the FPC 290.

[0273] The display module 280 can be configured such that the pixel circuit unit 283 or the circuit unit 282 is stacked below the pixel unit 284, thereby enabling the aperture ratio (effective display area ratio) of the display unit 281 to be extremely high. For example, the aperture ratio of the display unit 281 can be set to 40% or more and less than 100%, preferably 50% or more and 95% or less, and more preferably 60% or more and 95% or less. Furthermore, the pixels 284a can be arranged at an extremely high density, enabling the resolution of the display unit 281 to be extremely high. For example, it is preferable that the pixels 284a are arranged in the display unit 281 at a resolution of 2000 ppi or more, preferably 3000 ppi or more, more preferably 5000 ppi or more, and even more preferably 6000 ppi or more, and 20000 ppi or less, or 30000 ppi or less.

[0274] Such a display module 280 has extremely high resolution and can therefore be suitably used in VR devices such as head-mounted displays or eyeglass-type AR devices. For example, even in a configuration in which the display unit of the display module 280 is viewed through lenses, the display module 280 has an extremely high-resolution display unit 281, so that even if the display unit is enlarged with the lenses, the pixels are not visible, allowing for a highly immersive display. Furthermore, the display module 280 is not limited to this, and can be suitably used in electronic devices having relatively small display units. For example, it can be suitably used in the display unit of a wearable electronic device such as a wristwatch.

[0275] This embodiment mode can be implemented by appropriately combining at least a part thereof with other embodiment modes described in this specification.

[0276] (Embodiment 2) In this embodiment, a display device of one embodiment of the present invention will be described with reference to FIGS.

[0277] 13A includes a pixel portion 502, a driver circuit portion 504, a protective circuit 506, and a terminal portion 507. Note that the display device of one embodiment of the present invention does not necessarily need to include the protective circuit 506.

[0278] The pixel section 502 has a plurality of pixel circuits 501 arranged in X rows and Y columns (X and Y are each independently a natural number of 2 or more). Each pixel circuit 501 has a circuit for driving a display element.

[0279] The driver circuit unit 504 includes driver circuits such as a gate driver 504a that outputs scan signals to the gate lines GL_1 to GL_X and a source driver 504b that supplies data signals to the data lines DL_1 to DL_Y. The gate driver 504a may include at least a shift register. The source driver 504b may include, for example, a plurality of analog switches. Alternatively, the source driver 504b may include a shift register.

[0280] The terminal portion 507 is a portion provided with terminals for inputting power, control signals, image signals, and the like from an external circuit to the display device.

[0281] 13A is connected to various wirings, such as a gate line GL that is a wiring between a gate driver 504a and a pixel circuit 501, or a data line DL that is a wiring between a source driver 504b and a pixel circuit 501.

[0282] Furthermore, the gate driver 504a and the source driver 504b may be provided on the same substrate as the pixel unit 502, or a substrate on which a gate driver circuit or a source driver circuit is separately formed (for example, a drive circuit substrate formed of a single crystal semiconductor or a polycrystalline semiconductor) may be mounted on the substrate by COG or TAB (Tape Automated Bonding).

[0283] In particular, it is preferable to arrange the gate driver 504 a and the source driver 504 b below the pixel section 502 .

[0284] Furthermore, the plurality of pixel circuits 501 shown in FIG. 13A can have, for example, the configuration shown in FIG. 13B.

[0285] 13B includes transistors 552 and 554, a capacitor 562, and a light-emitting element 572. The pixel circuit 501 is connected to a data line DL_n, a gate line GL_m, a potential supply line VL_a, a potential supply line VL_b, and the like.

[0286] A high power supply potential VDD is applied to one of the potential supply lines VL_a and VL_b, and a low power supply potential VSS is applied to the other. The current flowing through the light-emitting element 572 is controlled in accordance with the potential applied to the gate of the transistor 554, thereby controlling the luminance of light emitted from the light-emitting element 572.

[0287] This embodiment mode can be implemented by appropriately combining at least a part thereof with other embodiment modes described in this specification.

[0288] (Embodiment 3) A pixel circuit including a memory for correcting a gray scale displayed in a pixel, which can be applied to a display device of one embodiment of the present invention, and a display device including the pixel circuit will be described below.

[0289] [Circuit configuration] 14A shows a circuit diagram of a pixel circuit 400. The pixel circuit 400 includes a transistor M1, a transistor M2, a capacitor C1, and a circuit 401. The pixel circuit 400 is connected to a wiring S1, a wiring S2, a wiring G1, and a wiring G2.

[0290] The transistor M1 has a gate connected to the wiring G1, one of a source and a drain connected to the wiring S1, and the other connected to one electrode of the capacitor C1. The transistor M2 has a gate connected to the wiring G2, one of a source and a drain connected to the wiring S2, and the other connected to the other electrode of the capacitor C1 and the circuit 401.

[0291] The circuit 401 is a circuit including at least one display element. Various elements can be used as the display element, but typically, a light-emitting element such as an organic EL element or an LED element can be used. In addition, a liquid crystal element, a MEMS (Micro Electro Mechanical Systems) element, or the like can also be used.

[0292] The node connecting the transistor M1 and the capacitor C1 is referred to as a node N1, and the node connecting the transistor M2 and the circuit 401 is referred to as a node N2.

[0293] In the pixel circuit 400, the potential of the node N1 can be maintained by turning off the transistor M1. In addition, the potential of the node N2 can be maintained by turning off the transistor M2. In addition, by writing a predetermined potential to the node N1 via the transistor M1 while the transistor M2 is in the off state, the potential of the node N2 can be changed in accordance with the change in the potential of the node N1 due to capacitive coupling via the capacitor C1.

[0294] Here, the transistor including an oxide semiconductor, as exemplified in Embodiment 1, can be used as one or both of the transistors M1 and M2. Therefore, the potentials of the nodes N1 and N2 can be held for a long period of time due to an extremely low off-state current. Note that when the period for holding the potentials of the nodes is short (specifically, when the frame frequency is 30 Hz or higher), a transistor including a semiconductor such as silicon may be used.

[0295] [Drive method example] Next, an example of an operation method of pixel circuit 400 will be described with reference to Fig. 14B. Fig. 14B is a timing chart relating to the operation of pixel circuit 400. Note that, to simplify the explanation, the influence of various resistances such as wiring resistance, parasitic capacitance of transistors or wiring, threshold voltage of transistors, etc. will not be taken into consideration here.

[0296] 14B, one frame period is divided into period T1 and period T2. Period T1 is a period in which a potential is written to node N2, and period T2 is a period in which a potential is written to node N1.

[0297] [Period T1] In the period T1, a potential that turns on the transistor is applied to both the wiring G1 and the wiring G2. In addition, a fixed potential V ref is supplied to the line S2, and the first data potential V w supply.

[0298] The node N1 is connected to the line S1 via the transistor M1. ref The node N2 is supplied with a first data potential V w Therefore, the capacitance C1 has a potential difference V w -V ref is maintained.

[0299] [Period T2] Subsequently, in a period T2, a potential that turns on the transistor M1 is applied to the wiring G1, and a potential that turns off the transistor M2 is applied to the wiring G2. data A predetermined constant potential is applied to the wiring S2, or the wiring S2 may be in a floating state.

[0300] The node N1 receives a second data potential V data At this time, the second data potential V dataIn other words, the potential of the node N2 changes by a potential dV in response to the first data potential V w The potential obtained by adding the second data potential V to the potential dV is input. Note that although the potential dV is shown as a positive value in FIG. 14B, it may be a negative value. That is, data is the potential V ref It may be lower.

[0301] Here, the potential dV is roughly determined by the capacitance value of the capacitor C1 and the capacitance value of the circuit 401. When the capacitance value of the capacitor C1 is sufficiently larger than the capacitance value of the circuit 401, the potential dV is equal to the second data potential V data The potential is close to

[0302] In this way, the pixel circuit 400 can generate a potential to be supplied to the circuit 401 including a display element by combining two types of data signals, and therefore, it is possible to perform gray scale correction within the pixel circuit 400.

[0303] The pixel circuit 400 can also generate a potential that exceeds the maximum potential that can be supplied to the wirings S1 and S2. For example, when a light-emitting element is used, high dynamic range (HDR) display or the like can be performed. Furthermore, when a liquid crystal element is used, overdrive driving or the like can be realized.

[0304] [Application example] 14C includes a circuit 401EL. The circuit 401EL includes a light-emitting element EL, a transistor M3, and a capacitor C2.

[0305] The transistor M3 has a gate connected to the node N2 and one electrode of the capacitor C2, and one of its source and drain connected to the potential V H The other electrode of the capacitor C2 is connected to a wiring that supplies a potential V com The other electrode of the light-emitting element EL is connected to a wiring that provides a potential V L Connect with the provided wiring.

[0306] The transistor M3 has a function of controlling the current supplied to the light-emitting element EL. The capacitor C2 functions as a storage capacitor. The capacitor C2 can be omitted if it is not necessary.

[0307] Although the anode side of the light-emitting element EL is connected to the transistor M3 in this example, the transistor M3 may be connected to the cathode side. H and potential V L The value of can be changed as appropriate.

[0308] In the pixel circuit 400EL, by applying a high potential to the gate of the transistor M3, a large current can flow through the light-emitting element EL, thereby realizing, for example, HDR display, etc. Furthermore, by supplying a correction signal to the wiring S1 or the wiring S2, it is possible to correct variations in the electrical characteristics of the transistor M3 or the light-emitting element EL.

[0309] It should be noted that the circuit is not limited to that shown in FIG. 14C, and a configuration in which a separate transistor or capacitor is added may also be used.

[0310] This embodiment mode can be implemented by appropriately combining at least a part thereof with other embodiment modes described in this specification.

[0311] (Fourth embodiment) In this embodiment, structural examples of electronic devices to which the display device of one embodiment of the present invention is applied will be described.

[0312] The display device and the display module of one embodiment of the present invention can be applied to a display portion of an electronic device having a display function, etc. Examples of such electronic devices include electronic devices with relatively large screens such as television devices, notebook personal computers, monitor devices, digital signage, pachinko machines, and game machines, as well as digital cameras, digital video cameras, digital photo frames, mobile phones, portable game machines, personal digital assistants, and sound players.

[0313] In particular, the display device and the display module of one embodiment of the present invention can have high resolution and can therefore be suitably used in electronic devices having a relatively small display area. Examples of such electronic devices include wristwatch-type and bracelet-type information terminals (wearable devices), VR devices such as head-mounted displays, and head-mountable wearable devices such as glasses-type AR devices.

[0314] 15A shows a perspective view of eyeglass-type electronic device 700. Electronic device 700 has a pair of display panels 701, a pair of housings 702, a pair of optical members 703, a pair of mounting portions 704, and the like.

[0315] The electronic device 700 can project an image displayed on the display panel 701 onto a display area 706 of the optical member 703. Furthermore, because the optical member 703 is translucent, the user can see the image displayed in the display area 706 superimposed on a transmitted image visually recognized through the optical member 703. Therefore, the electronic device 700 is an electronic device capable of AR display.

[0316] One of the housings 702 is provided with a camera 705 that can capture an image in front of it. Although not shown, one of the housings 702 is provided with a connector to which a wireless receiver or a cable can be connected, and a video signal or the like can be supplied to the housing 702. By providing an acceleration sensor such as a gyro sensor in the housing 702, the orientation of the user's head can be detected and an image corresponding to that orientation can be displayed in the display area 706. The housing 702 is preferably provided with a battery, which can be charged wirelessly or via a wired connection.

[0317] 15B, a method for projecting an image onto display area 706 of electronic device 700 will be described. A display panel 701, a lens 711, and a reflector 712 are provided inside housing 702. In addition, a portion of optical member 703 corresponding to display area 706 has a reflecting surface 713 that functions as a half mirror.

[0318] Light 715 emitted from the display panel 701 passes through the lens 711 and is reflected by the reflector 712 toward the optical member 703. Inside the optical member 703, the light 715 is repeatedly totally reflected at the end face of the optical member 703 and reaches the reflecting surface 713, whereby an image is projected onto the reflecting surface 713. This allows the user to view both the light 715 reflected by the reflecting surface 713 and the transmitted light 716 that has passed through the optical member 703 (including the reflecting surface 713).

[0319] 15 shows an example in which the reflector 712 and the reflecting surface 713 each have a curved surface. This allows for greater freedom in optical design and allows for a thinner optical member 703 than when these surfaces are flat. Note that the reflector 712 and the reflecting surface 713 may also be flat.

[0320] A member having a mirror surface, preferably one with high reflectivity, can be used as the reflector 712. Furthermore, a half mirror utilizing reflection from a metal film may be used as the reflecting surface 713, but the transmittance of the transmitted light 716 can be increased by using a prism or the like utilizing total reflection.

[0321] Here, the housing 702 preferably has a mechanism for adjusting the distance between the lens 711 and the display panel 701 or the angle therebetween. This makes it possible to adjust the focus, enlarge or reduce the image, etc. For example, the lens 711 or the display panel 701 or both may be configured to be movable in the direction of the optical axis.

[0322] Furthermore, it is preferable that the housing 702 has a mechanism that can adjust the angle of the reflector 712. By changing the angle of the reflector 712, it is possible to change the position of the display area 706 where an image is displayed. This makes it possible to position the display area 706 in an optimal position according to the position of the user's eyes.

[0323] The display device or display module of one embodiment of the present invention can be applied to the display panel 701. Therefore, the electronic device 700 can provide an extremely high-resolution display.

[0324] 16A and 16B show perspective views of a goggle-type electronic device 750. Fig. 16A is a perspective view showing the front, top, and left side of electronic device 750, and Fig. 16B is a perspective view showing the back, bottom, and right side of electronic device 750.

[0325] Electronic device 750 includes a pair of display panels 751, a housing 752, a pair of mounting portions 754, a buffer member 755, and a pair of lenses 756. The pair of display panels 751 are provided inside housing 752 at positions that can be viewed through lenses 756.

[0326] The electronic device 750 is an electronic device for VR. A user wearing the electronic device 750 can view an image displayed on a display panel 751 through a lens 756. Also, by displaying different images on a pair of display panels 751, a three-dimensional display using parallax can be performed.

[0327] Furthermore, an input terminal 757 and an output terminal 758 are provided on the rear side of the housing 752. A cable for supplying a video signal from a video output device or the like, or power for charging a battery provided within the housing 752, can be connected to the input terminal 757. The output terminal 758 functions as, for example, an audio output terminal, and earphones, headphones, etc. can be connected. Note that if the configuration is such that audio data can be output via wireless communication, or if audio is output from an external video output device, the audio output terminal need not be provided.

[0328] Furthermore, it is preferable that housing 752 has a mechanism that can adjust the left and right positions of lens 756 and display panel 751 so that they are optimally positioned according to the position of the user's eyes.It is also preferable that housing 752 has a mechanism that can adjust the focus by changing the distance between lens 756 and display panel 751.

[0329] The display device or display module of one embodiment of the present invention can be applied to the display panel 751. Therefore, the electronic device 750 can display images with extremely high resolution. This allows the user to feel a high sense of immersion.

[0330] The buffer member 755 is a portion that comes into contact with the user's face (forehead, cheeks, etc.). The close contact of the buffer member 755 with the user's face can prevent light leakage and enhance the sense of immersion. It is preferable to use a soft material for the buffer member 755 so that it can be in close contact with the user's face when the user wears the electronic device 750. For example, materials such as rubber, silicone rubber, urethane, and sponge can be used. Furthermore, using a sponge or the like with its surface covered with cloth, leather (natural leather or synthetic leather), or the like can prevent gaps from forming between the user's face and the buffer member 755, thereby effectively preventing light leakage. Furthermore, using such a material is preferable because it feels pleasant to the touch and prevents the user from feeling cold when worn in cold seasons. It is preferable that components that come into contact with the user's skin, such as the buffer member 755 or the attachment portion 754, be removable for easy cleaning or replacement.

[0331] This embodiment mode can be implemented by appropriately combining at least a part thereof with other embodiment modes described in this specification. [Explanation of symbols]

[0332] C1: capacitance, C2: capacitance, DL_Y: data line, DL_1: data line, G1: wiring, G2: wiring, GL_X: gate line, GL_1: gate line, M1: transistor, M2: transistor, M3: transistor, N1: node, N2: node, RES1: resist, RES2: resist, RES3: resist, S1: wiring, S2: wiring, T1: period, T2: period, 100: display device, 101: substrate, 111: conductive layer, 111a: conductive layer, 111b: conductive layer, 114: conductive layer, 114B: conductive layer, 114G: conductive layer, 114R: conductive layer, 115: EL layer, 11 5f: EL layer, 115a: EL layer, 115b: EL layer, 115B: EL layer, 115Bf: EL layer, 115G: EL layer, 115Gf: EL layer, 115R: EL layer, 115Rf: EL layer, 116: conductive layer, 116f: conductive layer, 117: insulator, 120: light-emitting element, 120B: light-emitting element, 120G: light-emitting element, 120R: light-emitting element, 121: insulating layer, 122: insulating layer, 124: insulating layer, 124a: layer, 124b: layer, 124c: layer, 125: insulating layer, 131: plug, 162: insulating layer, 163: insulating layer, 164: adhesive layer, 165B: colored layer, 165G: colored layer, 165R: colored layer, 200: display device, 200A: display device, 200B: display device, 200C: display device, 200D: display device, 201: substrate, 202: substrate, 210: transistor, 211: conductive layer, 212: low resistance region, 213: insulating layer, 214: insulating layer, 215: element isolation layer, 220: transistor, 221: semiconductor layer, 223: insulating layer, 224: conductive layer, 225: conductive layer, 226: insulating layer, 227: conductive layer, 228: insulating layer, 229: insulating layer, 230: transistor, 231: insulating layer, 232: insulating layer, 240: capacitance element, 241: conductive layer, 24 2: conductive layer, 243: insulating layer, 251: conductive layer, 252: conductive layer, 253: conductive layer, 261: insulating layer, 261a: insulating layer, 261b: insulating layer, 262: insulating layer, 263: insulating layer, 264: insulating layer, 265: insulating layer, 271: plug, 271a: conductive layer, 271b: conductive layer, 272: plug, 273: plug, 274: plug, 280: display module, 281: display unit, 282: circuit unit, 283: pixel circuit unit, 283a: pixel circuit, 284: pixel unit, 284a: pixel, 285: terminal unit, 286: wiring unit, 290: FPC, 290b: source driver IC,400: pixel circuit, 400EL: pixel circuit, 401: circuit, 401EL: circuit, 501: pixel circuit, 502: pixel unit, 504: drive circuit unit, 504a: gate driver, 504b: source driver, 506: protection circuit, 507: terminal unit, 552: transistor, 554: transistor, 562: capacitance element, 572: light-emitting element, 700: electronic device, 701: display panel, 702: housing, 703: optical member, 704: mounting unit, 705: camera La, 706: display area, 711: lens, 712: reflector, 713: reflective surface, 715: light, 716: transmitted light, 750: electronic device, 751: display panel, 752: housing, 754: mounting part, 755: cushioning material, 756: lens, 757: input terminal, 758: output terminal, 4411: light-emitting layer, 4412: light-emitting layer, 4413: light-emitting layer, 4420: layer, 4420-1: layer, 4420-2: layer, 4430: layer, 4430-1: layer, 4430-2: layer,

Claims

1. A light-emitting element, It has a first insulating layer disposed to cover the light-emitting element, The light-emitting element is A first conductive layer and A second insulating layer having a region that covers the upper and side surfaces at the end of the first conductive layer, The EL layer on the first conductive layer and the second insulating layer, The EL layer comprises a second conductive layer, The first insulating layer is The first layer and, The second layer on the first layer, The third layer is located on the second layer, The first layer has the function of capturing or fixing at least one of water and oxygen, The second layer has the function of suppressing the diffusion of at least one of water and oxygen. The third layer has a higher carbon concentration than at least one of the first layer and the second layer. The thickness of the second layer is greater than the thickness of the first layer and greater than the thickness of the third layer. The thickness of the first layer is greater than the thickness of the third layer. In cross-sectional view, the EL layer has a region in contact with the upper surface of the first conductive layer and a region in contact with the upper surface of the second insulating layer. In a cross-sectional view, the second conductive layer has a region that overlaps with the first conductive layer via the EL layer, a region that overlaps with the first conductive layer via the EL layer and the second insulating layer, and a region that overlaps with the EL layer and the second insulating layer but does not overlap with the first conductive layer. In a cross-sectional view, the first insulating layer has a region in contact with the upper surface of the second conductive layer, a region in contact with the side surface of the second conductive layer, a region in contact with the side surface of the EL layer, and a region in contact with the side surface of the second insulating layer, but does not have a region in contact with the upper surface of the EL layer or a region in contact with the upper surface of the second insulating layer. Display device.

2. A transistor on a substrate, The first insulating layer on the transistor, A plug arranged to be embedded in the first insulating layer, The light-emitting element on the first insulating layer, It comprises a second insulating layer disposed to cover the light-emitting element, The light-emitting element is A first conductive layer and A third insulating layer having a region that covers the upper and side surfaces at the end of the first conductive layer, The EL layer on the first conductive layer and the third insulating layer, The EL layer comprises a second conductive layer, The plug electrically connects one of the source and drain of the transistor to the first conductive layer. The second insulating layer is The first layer and, The second layer on the first layer, The third layer is located on the second layer, The first layer has the function of capturing or fixing at least one of water and oxygen, The second layer has the function of suppressing the diffusion of at least one of water and oxygen. The third layer has a higher carbon concentration than at least one of the first layer and the second layer. The thickness of the second layer is greater than the thickness of the first layer and greater than the thickness of the third layer. The thickness of the first layer is greater than the thickness of the third layer. In a cross-sectional view, the EL layer has a region in contact with the upper surface of the first conductive layer and a region in contact with the upper surface of the third insulating layer. In a cross-sectional view, the second conductive layer has a region that overlaps with the first conductive layer via the EL layer, a region that overlaps with the first conductive layer via the EL layer and the third insulating layer, and a region that overlaps with the EL layer and the third insulating layer and does not overlap with the first conductive layer. In cross-sectional view, the second insulating layer has a region in contact with the upper surface of the second conductive layer, a region in contact with the side surface of the second conductive layer, a region in contact with the side surface of the EL layer, and a region in contact with the side surface of the third insulating layer, but does not have a region in contact with the upper surface of the EL layer or a region in contact with the upper surface of the third insulating layer. Display device.

3. In claim 1 or 2, The first layer comprises oxygen and aluminum, and is a display device.

4. In claim 1 or 2, The first layer comprises oxygen and hafnium, wherein the display device is provided.

5. In any one of claims 1 to 4, The display device comprising the second layer of nitrogen and silicon.

6. In any one of claims 1 to 5, A display device wherein the third layer has a higher hydrogen concentration than at least one of the first layer and the second layer.

7. In any one of claims 1 to 6, The third layer comprises oxygen and aluminum, and is a display device.

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