Method for manufacturing a display device

Abstract

This invention provides a method for manufacturing a novel display device. [Solution] An anode is formed on an insulating layer, an EL layer is formed on the anode, and a cathode is formed on the EL layer. Multiple light-emitting elements are formed by selectively removing parts of the anode, EL layer, and cathode without providing partitions. A light-transmitting conductive layer is formed to cover the multiple light-emitting elements. The cathode of each of the multiple light-emitting elements is electrically connected to the conductive layer.

Description

[Technical Field]

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

[0002] Furthermore, one aspect of the present invention is not limited to the above-mentioned technical field. The technical field of one aspect of the invention disclosed herein relates to a product, method, or method of manufacture. Alternatively, one aspect of the present invention relates to a process, machine, manufacture, or composition of matter. More specifically, examples of the technical field of one aspect of the present invention disclosed herein include semiconductor devices, display devices, light-emitting devices, energy storage devices, memory devices, methods for driving them, or methods for manufacturing them. [Background technology]

[0003] As a display device, an active-matrix type display device is known, which has a transistor for driving the display element in each pixel. For example, there are active-matrix liquid crystal display devices (also called "liquid crystal displays") that use liquid crystal elements as the display element, and active-matrix light-emitting display devices (also called "organic EL displays") that use light-emitting elements such as organic EL elements as the display element.

[0004] Organic EL displays, being self-emissive display devices, offer wider viewing angles and higher responsiveness than liquid crystal displays. Furthermore, because organic EL displays do not require a backlight, they facilitate weight reduction, thinning, and lower power consumption, leading to extensive research in recent years. Organic EL elements, functioning as pixels, have a configuration where the anode and cathode overlap via an emissive layer. Additionally, in organic EL displays, partitions are provided between adjacent pixels to prevent electrical interference between adjacent emissive layers (Patent Document 1).

[0005] Furthermore, when forming organic EL layers such as light-emitting layers using low-molecular-weight materials, a method using vacuum deposition with a metal mask is known (Patent Document 2).

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0007] The partition provided between pixels (also referred to as "bank" or "dam") has effects such as improving the display quality and reducing power consumption of the display device. On the other hand, in order to obtain sufficient effects, a certain amount of partition is required, so it is difficult to reduce the occupied area of the partition, and it has been difficult to achieve an improvement in pixel aperture ratio, high definition, and miniaturization.

[0008] In addition, since the metal mask has inferior dimensional accuracy compared to the resist mask, it has been difficult to achieve an improvement in pixel aperture ratio, high definition, etc. in the formation of the light-emitting layer using the metal mask. Also, the metal mask has a problem that it is easily deformed by the influence of heat generated at the evaporation source.

[0009] One aspect of the present invention aims to provide a display device or a semiconductor device with good display quality. Or, one aspect of the present invention aims to provide a display device or a semiconductor device with high reliability. Or, one aspect of the present invention aims to provide a display device or a semiconductor device with low power consumption. Or, one aspect of the present invention aims to provide a lightweight display device or a semiconductor device. Or, one aspect of the present invention aims to provide a display device or a semiconductor device with high productivity. Or, one aspect of the present invention aims to provide a novel display device or a semiconductor device.

[0010] Furthermore, the description of these problems does not preclude the existence of other problems. Moreover, one aspect of the present invention does not need to solve all of these problems. Other problems will naturally become apparent from the description in the specification, drawings, and claims, and it is possible to extract other problems from the description in the specification, drawings, and claims. [Means for solving the problem]

[0011] (1) One aspect of the present invention is a method for manufacturing a display device comprising the steps of forming an anode on an insulating layer, forming an EL layer on the anode, forming a cathode on the EL layer, selectively removing a portion of the anode, the EL layer, and the cathode to form a plurality of light-emitting elements, and forming a conductive layer covering the plurality of light-emitting elements, wherein the cathode of each of the plurality of light-emitting elements is electrically connected to the conductive layer, and the conductive layer is light-transmitting.

[0012] (2) Another aspect of the present invention is a method for manufacturing a display device, comprising the steps of: forming an anode on an insulating layer; forming an EL layer on the anode; forming a cathode on the EL layer; selectively removing a portion of each of the anode, EL layer, and cathode to form a plurality of light-emitting elements; and forming a conductive layer on the plurality of light-emitting elements, wherein at least a portion of the plurality of light-emitting elements have cathodes of adjacent light-emitting elements that are electrically connected to the conductive layer.

[0013] Another aspect of the present invention is a method for manufacturing a display device, comprising the steps of (1) or (2) of forming a plurality of transistors on a substrate and forming an insulating layer on the plurality of transistors, wherein the insulating layer has a surface on which the surface of the insulating layer is formed has reduced irregularities.

[0014] The transistor preferably contains an oxide semiconductor in the semiconductor layer where the channel is formed. The oxide semiconductor preferably contains at least one of indium or zinc. [Effects of the Invention]

[0015] According to one aspect of the present invention, it is possible to provide a display device or semiconductor device with good display quality, or a highly reliable display device or semiconductor device, or a low power consumption display device or semiconductor device, or a lightweight display device or semiconductor device, or a highly productive display device or semiconductor device, or a novel display device or semiconductor device.

[0016] Furthermore, the description of these effects does not preclude the existence of other effects. Moreover, one embodiment of the present invention does not need to possess all of these effects. Other effects will naturally become apparent from the description in the specification, drawings, and claims, and it is possible to extract other effects from the description in the specification, drawings, and claims. [Brief explanation of the drawing]

[0017] [Figure 1] Figures 1A to 1C illustrate examples of the configuration of a display device. [Figure 2] Figures 2A and 2C illustrate an example of a method for manufacturing the first element substrate. [Figure 3] Figures 3A and 3B illustrate an example of a method for fabricating the first element substrate. [Figure 4] Figures 4A and 4B illustrate an example of a method for fabricating the first element substrate. [Figure 5] Figures 5A and 5B illustrate an example of a method for fabricating the first element substrate. [Figure 6] Figures 6A and 6B illustrate an example of a method for fabricating the first element substrate. [Figure 7] Figures 7A1, 7A2, and 7B illustrate an example of a method for fabricating the first element substrate. [Figure 8] Figures 8A and 8B illustrate an example of a method for fabricating the first element substrate. [Figure 9] Figures 9A and 9B illustrate modified examples of the first element substrate. [Figure 10]Figure 10 illustrates a modified example of the first element substrate. [Figure 11] Figures 11A to 11C illustrate an example of a method for manufacturing the second element substrate. [Figure 12] Figure 12 illustrates an example of a method for manufacturing a display device. [Figure 13] Figure 13 illustrates a modified example of the display device. [Figure 14] Figure 14A is a diagram illustrating the classification of crystal structures. Figure 14B is a diagram illustrating the XRD spectrum of the CAAC-IGZO film. Figure 14C is a diagram illustrating the micro-electron diffraction pattern of the CAAC-IGZO film. [Figure 15] Figures 15A and 15B1 to 15B5 illustrate examples of the configuration of a display device. [Figure 16] Figure 16 illustrates an example of a pixel circuit configuration. [Figure 17] Figures 17A to 17C illustrate examples of the configuration of light-emitting elements. [Figure 18] Figures 18A to 18F show examples of electronic devices. [Modes for carrying out the invention]

[0018] In this specification, a semiconductor device refers to a device that utilizes semiconductor properties, including circuits containing semiconductor elements (transistors, diodes, photodiodes, etc.), devices having such circuits, etc. It also refers to any device that can function by utilizing semiconductor properties. For example, integrated circuits, chips equipped with integrated circuits, and electronic components with chips housed in packages are examples of semiconductor devices. Furthermore, memory devices, display devices, light-emitting devices, lighting devices, and electronic devices are themselves semiconductor devices and may contain semiconductor devices.

[0019] Furthermore, when it is stated in this specification that X and Y are connected, it is assumed that this specification discloses the cases in which X and Y are electrically connected, functionally connected, and directly connected. Therefore, it is assumed that the disclosed connections are not limited to predetermined connections, such as those shown in the figures or text, but also include connections other than those shown in the figures or text. X and Y are objects (e.g., devices, elements, circuits, wiring, electrodes, terminals, conductive films, layers, etc.).

[0020] One example of a case where X and Y are electrically connected is that one or more elements that enable electrical connection between X and Y (e.g., switches, transistors, capacitive elements, inductors, resistors, diodes, display devices, light-emitting devices, loads, etc.) can be connected between X and Y. Note that a switch has an on state and an off state. In other words, a switch has the function of controlling whether or not current flows by being in a conductive state (on state) or a non-conductive state (off state).

[0021] One example of a functional connection between X and Y is when one or more circuits that enable the functional connection between X and Y (for example, logic circuits (inverters, NAND gates, NOR gates, etc.), signal conversion circuits (digital-to-analog conversion circuits, analog-to-digital conversion circuits, gamma correction circuits, etc.), potential level conversion circuits (power supply circuits (boost circuits, buck circuits, etc.), level shifter circuits that change the potential level of a signal, etc.), voltage sources, current sources, switching circuits, amplification circuits (circuits that can increase the signal amplitude or current amount, such as operational amplifiers, differential amplifiers, source follower circuits, buffer circuits, etc.), signal generation circuits, memory circuits, control circuits, etc.) can be connected between X and Y.

[0022] Furthermore, when it is explicitly stated that X and Y are electrically connected, this includes both cases where X and Y are electrically connected (i.e., connected with another element or circuit in between) and cases where X and Y are directly connected (i.e., connected without another element or circuit in between).

[0023] Furthermore, for example, it can be expressed as, "X, Y, the source (or first terminal, etc.) and drain (or second terminal, etc.) of the transistor are electrically connected to each other, and the connection is in the order of X, the source (or first terminal, etc.) of the transistor, the drain (or second terminal, etc.) of the transistor, and Y." Alternatively, it can be expressed as, "The source (or first terminal, etc.) of the transistor is electrically connected to X, and the drain (or second terminal, etc.) of the transistor is electrically connected to Y, and X, the source (or first terminal, etc.) of the transistor, the drain (or second terminal, etc.) of the transistor, and Y are electrically connected in this order." Alternatively, it can be expressed as, "X is electrically connected to Y via the source (or first terminal, etc.) and drain (or second terminal, etc.) of the transistor, and X, the source (or first terminal, etc.) of the transistor, the drain (or second terminal, etc.) of the transistor, and Y are provided in this connection order." By using similar notation to these examples to define the order of connections in a circuit configuration, the source (or first terminal, etc.) and drain (or second terminal, etc.) of a transistor can be distinguished and their technical scopes determined. Note that these notational methods are examples only and are not limited to them. Here, X and Y are objects (e.g., devices, elements, circuits, wiring, electrodes, terminals, conductive films, layers, etc.).

[0024] Even if independent components are shown as electrically connected in a circuit diagram, a single component may possess the functions of multiple components. For example, if part of a wire also functions as an electrode, a single conductive film possesses the functions of both the wire and the electrode. Therefore, in this specification, "electrically connected" includes cases where a single conductive film possesses the functions of multiple components.

[0025] Furthermore, in this specification, the term "resistive element" can refer to, for example, a circuit element or wiring having a resistance value higher than 0Ω. Therefore, in this specification, the term "resistive element" includes wiring having a resistance value, transistors, diodes, coils, etc., through which current flows between the source and drain. Therefore, the term "resistive element" can be replaced with terms such as "resistance," "load," or "region having a resistance value," and conversely, the terms "resistance," "load," or "region having a resistance value" can be replaced with terms such as "resistive element." The resistance value can be, for example, preferably 1mΩ or more and 10Ω or less, more preferably 5mΩ or more and 5Ω or less, and even more preferably 10mΩ or more and 1Ω or less. Also, for example, 1Ω or more and 1 × 10 9 It may also be less than or equal to Ω.

[0026] Furthermore, when using wiring as a resistive element, the resistance value may be determined by the length of the wiring. Alternatively, a conductor with a different resistivity than the conductor used for the wiring may be used as the resistive element. Or, the resistance value may be determined by doping the semiconductor with impurities.

[0027] Furthermore, in this specification, "capacitive element" refers to, for example, a circuit element having a capacitance value higher than 0F, a region of wiring having a capacitance value higher than 0F, parasitic capacitance, the gate capacitance of a transistor, etc. Therefore, in this specification, "capacitive element" includes not only a circuit element comprising a pair of electrodes and a dielectric material contained between the electrodes, but also parasitic capacitance occurring between wirings, the gate capacitance occurring between one of the sources or drains of a transistor and the gate, etc. Also, terms such as "capacitive element," "parasitic capacitance," and "gate capacitance" can be replaced with terms such as "capacitance," and conversely, the term "capacitance" can be replaced with terms such as "capacitive element," "parasitic capacitance," and "gate capacitance." Also, the term "a pair of electrodes" in "capacitance" can be replaced with terms such as "a pair of conductors," "a pair of conductive regions," or "a pair of regions." The capacitance value can be, for example, 0.05fF or more and 10pF or less. Alternatively, it may be, for example, 1pF or more and 10μF or less.

[0028] Furthermore, in this specification, a transistor has three terminals called the gate, source, and drain. The gate is a control terminal that controls the conduction state of the transistor. The two terminals that function as either the source or the drain are the input and output terminals of the transistor. Depending on the conductivity type of the transistor (n-channel type, p-channel type) and the potential applied to the three terminals of the transistor, one of the two input and output terminals becomes the source and the other becomes the drain. For this reason, in this specification, the terms source and drain can be used interchangeably. Also, in this specification, when describing the connection relationships of a transistor, the notation "one of the source or drain" (or first electrode, or first terminal) and "the other of the source or drain" (or second electrode, or second terminal) is used. Depending on the structure of the transistor, in addition to the three terminals described above, there may be a back gate. In this case, in this specification, one of the gate or back gate of the transistor may be called the first gate, and the other of the gate or back gate of the transistor may be called the second gate. Furthermore, in the same transistor, the terms "gate" and "back gate" may be interchangeable. Furthermore, if a transistor has three or more gates, in this specification, each gate may be referred to as the first gate, second gate, third gate, and so on.

[0029] Furthermore, in this specification, the term "node" can be replaced with terminals, wiring, electrodes, conductive layers, conductors, impurity regions, etc., depending on the circuit configuration, device structure, etc. Also, terminals, wiring, etc. can be replaced with "node".

[0030] Furthermore, in this specification, "voltage" and "potential" may be used interchangeably as appropriate. "Voltage" is the potential difference from a reference potential. For example, if the reference potential is the ground potential (earth potential), then "voltage" can be replaced with "potential." Note that the ground potential does not necessarily mean 0V. Also, potential is relative, and as the reference potential changes, the potential applied to the wiring, the potential applied to the circuit, and the potential output from the circuit also change.

[0031] Furthermore, in this specification, the terms "high-level potential" (also referred to as "high-level potential," "H potential," or "H") and "low-level potential" (also referred to as "low-level potential," "L potential," or "L") do not mean specific potentials. For example, if two wires are both described as "functioning as wires that supply a high-level potential," the high-level potentials provided by each wire do not have to be equal. Similarly, if two wires are both described as "functioning as wires that supply a low-level potential," the low-level potentials provided by each wire do not have to be equal.

[0032] "Electric current" refers to the phenomenon of electric charge movement (electrical conduction). For example, the statement "electrical conduction is occurring in a positively charged body" can be rephrased as "electrical conduction is occurring in the opposite direction in a negatively charged body." Therefore, in this specification, unless otherwise specified, "electric current" refers to the phenomenon of electric charge movement (electrical conduction) associated with the movement of carriers. Carriers here include electrons, holes, anions, cations, complex ions, etc., and the carriers differ depending on the system through which the current flows (e.g., semiconductors, metals, electrolytes, vacuum, etc.). Furthermore, the "direction of current" in wiring, etc., is the direction in which positive carriers move and is expressed as a positive current quantity. In other words, the direction in which negative carriers move is the opposite direction to the direction of the current and is expressed as a negative current quantity. Therefore, in this specification, if there is no specification regarding the positive or negative (or direction) of the current, a statement such as "current flows from element A to element B" can be rephrased as "current flows from element B to element A," etc. Furthermore, descriptions such as "current is input to element A" can be rephrased as "current is output from element A."

[0033] Furthermore, the ordinal numbers "1st," "2nd," and "3rd" in this specification are used to avoid confusion of constituent elements. Therefore, they do not limit the number of constituent elements, nor do they limit the order of the constituent elements. For example, a constituent element referred to as "1st" in one embodiment of this specification may be referred to as "2nd" in another embodiment or in the claims. Also, for example, a constituent element referred to as "1st" in one embodiment of this specification may be omitted in another embodiment or in the claims.

[0034] Furthermore, in this specification, phrases indicating arrangement such as "above," "below," "upward," or "downward" are sometimes used for convenience to explain the positional relationship between components with reference to the drawings. Also, the positional relationship between components changes as appropriate depending on the direction in which each component is depicted. Therefore, the phrases explained in the specification are not limited to those described and can be appropriately rephrased depending on the situation. For example, the expression "insulator located on the upper surface of the conductor" can be rephrased as "insulator located on the lower surface of the conductor" by rotating the orientation of the drawing shown by 180 degrees.

[0035] Furthermore, the terms "above" and "below" do not limit the positional relationship of the components to being directly above or below each other and in direct contact. For example, the expression "electrode B on insulating layer A" does not require electrode B to be formed in direct contact with insulating layer A, and does not exclude cases where other components are included between insulating layer A and electrode B.

[0036] Furthermore, in this specification, terms such as "film" and "layer" can be interchanged as needed. For example, the term "conductive layer" may be changed to the term "conductive film." Or, for example, the term "insulating film" may be changed to the term "insulating layer." Alternatively, depending on the circumstances, terms such as "film" and "layer" can be omitted and replaced with other terms. For example, the term "conductive layer" or "conductive film" may be changed to the term "conductor." Or, for example, the terms "insulating layer" or "insulating film" may be changed to the term "insulator."

[0037] Furthermore, in this specification, terms such as "electrode," "wiring," and "terminal" do not functionally limit these components. For example, "electrode" may be used as part of "wiring," and vice versa. Moreover, the terms "electrode" or "wiring" include cases where multiple "electrodes" or "wiring" are formed as a single unit. Similarly, for example, "terminal" may be used as part of "wiring" or "electrode," and vice versa. Furthermore, the term "terminal" also includes cases where multiple "electrodes," "wiring," or "terminals" are formed as a single unit. Therefore, for example, an "electrode" can be part of "wiring" or a "terminal," and for example, a "terminal" can be part of "wiring" or an "electrode." In addition, terms such as "electrode," "wiring," and "terminal" may be replaced with terms such as "region" depending on the circumstances.

[0038] Furthermore, in this specification, terms such as "wiring," "signal line," and "power line" can be interchanged with each other depending on the circumstances or situation. For example, the term "wiring" may be changed to the term "signal line." Also, for example, the term "wiring" may be changed to the term "power line," etc. Similarly, the reverse is also true; terms such as "signal line" and "power line" may be changed to the term "wiring." Terms such as "power line" may be changed to the term "signal line," etc. Similarly, the reverse is also true; terms such as "signal line" may be changed to the term "power line," etc. Also, the term "potential" applied to the wiring may be changed to the term "signal," etc., depending on the circumstances or situation. Similarly, the reverse is also true; terms such as "signal" may be changed to the term "potential."

[0039] In this specification, semiconductor impurities refer to elements other than the main components that make up the semiconductor layer. For example, elements with a concentration of less than 0.1 atomic percent are impurities. The presence of impurities can cause, for example, an increase in the defect level density of the semiconductor, a decrease in carrier mobility, and a decrease in crystallinity. When the semiconductor is an oxide semiconductor, impurities that alter the properties of the semiconductor include, for example, Group 1 elements, Group 2 elements, Group 13 elements, Group 14 elements, Group 15 elements, and transition metals other than the main components. In particular, examples include hydrogen (which is also found in water), lithium, sodium, silicon, boron, phosphorus, carbon, and nitrogen. Specifically, when the semiconductor is a silicon layer, impurities that alter the properties of the semiconductor include, for example, Group 1 elements (excluding oxygen and hydrogen), Group 2 elements, Group 13 elements, and Group 15 elements.

[0040] In this specification, a switch refers to a device that has the function of controlling whether or not to allow current to flow by being in a conductive (on) state or a non-conductive (off) state. Alternatively, a switch refers to a device that has the function of selecting and switching the path through which current flows. Examples include electrical switches and mechanical switches. In other words, a switch is not limited to any particular type, as long as it can control current.

[0041] Examples of electrical switches include transistors (e.g., bipolar transistors, MOS transistors), diodes (e.g., PN diodes, PIN diodes, Schottky diodes, MIM (Metal Insulator Metal) diodes, MIS (Metal Insulator Semiconductor) diodes, diode-connected transistors, etc.), or logic circuits combining these. When a transistor is used as a switch, the "conducting state" of the transistor refers to a state in which the source and drain electrodes of the transistor can be considered to be electrically short-circuited. Conversely, the "non-conducting state" of the transistor refers to a state in which the source and drain electrodes of the transistor can be considered to be electrically disconnected. When a transistor is simply operated as a switch, the polarity (conductivity type) of the transistor is not particularly limited.

[0042] One example of a mechanical switch is a switch using MEMS (Micro Electro Mechanical Systems) technology. This switch has mechanically movable electrodes, and it operates by controlling the conduction and non-conductivity through the movement of these electrodes.

[0043] In this specification, "parallel" means that two lines are positioned at an angle of -10° or more and 10° or less. Therefore, the case of -5° or more and 5° or less is also included. "Approximately parallel" or "roughly parallel" means that two lines are positioned at an angle of -30° or more and 30° or less. "Perpendicular" means that two lines are positioned at an angle of 80° or more and 100° or less. Therefore, the case of 85° or more and 95° or less is also included. "Approximately perpendicular" or "roughly perpendicular" means that two lines are positioned at an angle of 60° or more and 120° or less.

[0044] In this specification, "metal oxide" refers to an oxide of a metal in a broad sense. Metal oxides are classified into oxide insulators, oxide conductors (including transparent oxide conductors), oxide semiconductors (also called oxide semiconductors or simply OS), etc. For example, when a metal oxide is used in the semiconductor layer where the channel of a transistor is formed, the metal oxide may be referred to as an oxide semiconductor. In other words, when a metal oxide is used as the semiconductor layer where the channel of a transistor having at least one of amplification, rectification, and switching functions is formed, the metal oxide can be referred to as a metal oxide semiconductor. Furthermore, in this specification, a transistor containing a metal oxide or oxide semiconductor in the semiconductor layer where the channel is formed can be referred to as an "OS transistor."

[0045] Furthermore, in this specification, the configurations shown in each embodiment can be appropriately combined with the configurations shown in other embodiments to form one aspect of the present invention. Also, if multiple configuration examples are shown within one embodiment, these configuration examples can be appropriately combined with each other.

[0046] The embodiments described herein will be explained with reference to the drawings. However, it will be readily apparent to those skilled in the art that the embodiments can be implemented in many different ways, and their form and details can be modified in various ways without departing from the spirit and scope. Therefore, the present invention is not to be interpreted as being limited to the contents of the embodiments. In the configuration of the invention in the embodiments, the same reference numerals are used in common across different drawings for the same parts or parts having similar functions, and repeated explanations may be omitted. Also, in order to make the drawings easier to understand, some components may be omitted in perspective views or top views, etc.

[0047] Furthermore, in the drawings of this specification, the size, layer thickness, or area may be exaggerated for clarity. Therefore, it is not necessarily limited to the size or aspect ratio. The drawings are schematic representations of ideal examples and are not limited to the shapes or values ​​shown in the drawings. For example, they may include variations in signals, voltages, or currents due to noise, or variations in signals, voltages, or currents due to timing differences.

[0048] In this specification, when the same symbol is used for multiple elements, and especially when it is necessary to distinguish them, identifying characters such as "A", "a", "_1", "[i]", and "[m,n]" may be added to the end of the symbol. For example, one of the multiple colored layers 131 may be described as colored layer 131R, and another as colored layer 131G.

[0049] In this specification, devices fabricated using a metal mask or an FMM (Fine Metal Mask, a high-resolution metal mask) may be referred to as MM (Metal Mask) structured devices. Furthermore, in this specification, devices fabricated without using a metal mask or an FMM may be referred to as MML (Metal Maskless) structured devices.

[0050] (Embodiment 1) A display device 100 according to one aspect of the present invention will be described with reference to the drawings.

[0051] <<Example Configuration>> Figure 1A is a schematic perspective view of the display device 100. The display device 100 has a configuration in which substrates 111 and 121 are bonded together. The display device 100 has a display area 235, a peripheral circuit area 232, a peripheral circuit area 233, etc. Figure 1 shows an example in which an FPC 124 is mounted on the display device 100. Therefore, the configuration shown in Figure 1A can also be described as a display module having the display device 100 and the FPC 124.

[0052] Peripheral circuit areas 232 and 233 contain circuits for supplying signals to the display area 235. The circuits included in peripheral circuit areas 232 and 233 are sometimes collectively referred to as "peripheral drive circuits." Examples of circuits included in peripheral drive circuits include scan line drive circuits and signal line drive circuits.

[0053] Part or all of the peripheral drive circuitry may be implemented using an IC (integrated circuit). For example, an IC containing part or all of the peripheral drive circuitry may be mounted on the substrate 111 using a COG (Chip On Glass) method or a COF (Chip On Film) method, etc. Alternatively, the IC may be mounted on the FPC 124 using a COF method, etc.

[0054] The signals and power supplied to the display area 235, peripheral circuit area 232, and peripheral circuit area 233 are input externally via the FPC 124.

[0055] Furthermore, Figure 1A includes an enlarged view of a portion of the display area 235. The display area 235 contains multiple pixels 240 arranged in a matrix. Each pixel 240 includes pixels 230R, 230G, and 230B. In this specification, when describing aspects common to pixels 230R, 230G, and 230B, or when there is no need to distinguish between the three, they may simply be referred to as "pixel 230."

[0056] [Example of cross-sectional configuration] Figure 1B is a cross-sectional view of the area indicated by the dashed line A1-A2 in Figure 1A. Figure 1B shows a cross-section of part of the display area 235, part of the peripheral circuit area 233, and part of the area including the FPC 124.

[0057] Pixels 230R, 230G, and 230B each have a light-emitting element 170 as a display element. The light-emitting element 170 has an electrode 171 that functions as an anode, an EL layer 172, and an electrode 173 that functions as a cathode.

[0058] Furthermore, pixels 230R, 230G, and 230B each have a transistor 251 for driving the display element. Peripheral circuit regions 232 and 233 also contain multiple transistors. Figure 1B shows transistor 252 as an example of a transistor included in peripheral circuit region 233.

[0059] The display device 100 has transistors 251 and 252, a light-emitting element 170, a colored layer 131 (colored layer 131R, colored layer 131G, and colored layer 131B), a light-shielding layer 132, etc., between substrates 111 and 121. Substrates 111 and 121 are bonded together via an adhesive layer 142.

[0060] As the adhesive layer 142, various types of curing adhesives can be used, such as UV-curing adhesives, reaction-curing adhesives, thermosetting adhesives, and anaerobic adhesives. Examples of these adhesives include epoxy resins, acrylic resins, silicone resins, phenolic resins, polyimide resins, imide resins, PVC (polyvinyl chloride) resins, PVB (polyvinyl butyral) resins, and EVA (ethylene vinyl acetate) resins. Materials with low moisture permeability, such as epoxy resins, are particularly preferred. Two-component mixed resins may also be used. Adhesive sheets may also be used.

[0061] The substrate 121 is provided with an insulating layer 122, a colored layer 131, a light-shielding layer 132, and an insulating layer 133. The insulating layer 133 may also function as a planarizing layer. A "planarizing layer" refers to a layer having a surface with reduced irregularities on the surface to be formed.

[0062] Figure 1C shows an enlarged view of transistor 252. Note that transistor 251 can have a similar structure to transistor 252.

[0063] The transistor 252 has an electrode 221, a semiconductor layer 231, an electrode 224a, an electrode 224b, and an electrode 226. Electrode 221 is provided on an insulating layer 113, and an insulating layer 211 is provided covering electrode 221. The semiconductor layer 231 is provided on the insulating layer 211. Electrodes 224a and 224b are provided on the insulating layer 211, with electrode 224a having a region in contact with a portion of the semiconductor layer 231, and electrode 224b having a region in contact with another portion of the semiconductor layer 231. Either electrode 224a or electrode 224b can function as a source electrode. The other electrode 224a or electrode 224b can function as a drain electrode.

[0064] Furthermore, an insulating layer 210 is provided covering electrodes 224a, 224b, and the semiconductor layer 231. Electrode 226 is provided on the insulating layer 210. Electrode 226 has a region that overlaps with the semiconductor layer 231. An insulating layer 213 is provided covering electrode 226.

[0065] Figure 1B illustrates bottom-gate transistors as transistor 251 and transistor 252. Transistor 251 is a transistor (also called a driving transistor) that controls the current flowing to the light-emitting element 170.

[0066] Furthermore, an insulating layer 114 is provided on the insulating layer 213. The insulating layer 114 functions as a planarizing layer. Transistors 251 and 252 are covered by the insulating layer 213 and the insulating layer 114. The number of insulating layers covering the transistors is not limited and may be a single layer or two or more layers.

[0067] It is preferable to use a material that does not easily allow impurities such as water and hydrogen to diffuse in at least one layer of the insulating layer covering each transistor. This allows the insulating layer to function as a barrier film. With such a configuration, the diffusion of impurities from the outside to the transistor can be effectively suppressed, and a highly reliable display device can be realized.

[0068] In pixel 230, the electrode 171 is provided on the insulating layer 114. The electrode 171 is electrically connected to either the source or the drain of transistor 251 through an opening in the insulating layer 114.

[0069] Furthermore, an EL layer 172 is provided on electrode 171, and electrode 173 is provided on EL layer 172. Electrode 173 has a region that overlaps with electrode 171 via EL layer 172.

[0070] The light-emitting element 170 is covered by an insulating layer 115 and an insulating layer 116. The insulating layer 116 functions as a planarizing layer.

[0071] A conductive layer 118 is provided on an insulating layer 116. The conductive layer 118 is electrically connected to electrodes 173 via electrodes 117 embedded in the insulating layer 115 and the insulating layer 116. The conductive layer 118 is electrically connected to multiple electrodes 173 and functions as a common electrode.

[0072] Furthermore, the display device 100 shown in Figure 1B is provided with wiring 125, electrode 228, and electrode 229. The wiring 125 and electrode 228 are provided on the insulating layer 211. Electrode 229 is electrically connected to electrode 228 at an opening in the insulating layer 210 that overlaps with electrode 228. The wiring 125 and electrode 228 can be formed simultaneously in the same process as electrodes 224a and 224b. Electrode 229 can be formed simultaneously in the same process as electrode 226.

[0073] Furthermore, the FPC124 is electrically connected to the electrode 229 via the connecting layer 138. The electrode 229 is electrically connected to the peripheral drive circuit.

[0074] As the connecting layer 138, an anisotropic conductive film (ACF), an anisotropic conductive paste (ACP), etc., can be used.

[0075] The light-emitting element 170 is, for example, a top-emission type light-emitting element. The light-emitting element 170 has a laminated structure in which an electrode 171 that functions as an anode, an EL layer 172, and an electrode 173 that functions as a cathode are stacked in that order from the insulating layer 114 side.

[0076] If the light-emitting element 170 is a top-emission type light-emitting element, the electrode 171 has the function of reflecting visible light, and the electrode 173 has the function of transmitting visible light. In addition, the conductive layer 118 also has the function of transmitting visible light.

[0077] The EL layer 172 has at least an emissive layer. The EL layer 172 may also have layers other than the emissive layer that include a material with high hole injection properties, a material with high hole transport properties, a hole blocking material, a material with high electron injection properties, a material with high electron transport properties, an electron blocking material, or a bipolar material (a material with high electron transport and hole transport properties).

[0078] The light-emitting color of the light-emitting element 170 can be white, red, green, blue, cyan, magenta, or yellow, depending on the material that makes up the EL layer 172.

[0079] There are two methods for achieving color display: one involves combining a white-emitting light-emitting element 170 with a colored layer, and the other involves providing a different light-emitting element 170 for each pixel. The former method is more productive than the latter. On the other hand, the latter method requires creating a different EL layer 172 for each pixel, making it less productive than the former method. However, the latter method can produce a more color-pure emitted color than the former method. In addition to the latter method, the color purity can be further improved by adding a microcavity structure to the light-emitting element 170.

[0080] The EL layer 172 may use either low-molecular-weight compounds or high-molecular-weight compounds, and may also contain inorganic compounds. Each layer constituting the EL layer 172 can be formed by methods such as vapor deposition (including vacuum deposition), transfer, printing, inkjet, and coating.

[0081] The EL layer 172 may contain inorganic compounds such as quantum dots. For example, quantum dots can be used as the light-emitting layer to function as a light-emitting material.

[0082] In this embodiment, a light-emitting element 170 with a white emission color is used. The light 175 emitted by the light-emitting element 170 is emitted towards the substrate 121 through the colored layer 131. Depending on the material constituting the colored layer 131, the wavelength range of the light 175 transmitted through the colored layer 131 changes. That is, by transmitting light through the colored layer 131, the hue of the light 175 can be changed to red, green, blue, cyan, magenta, or yellow.

[0083] In this embodiment, light 175R, whose hue has been altered by passing through the colored layer 131R, is emitted from pixel 230R. Light 175G, whose hue has been altered by passing through the colored layer 131G, is emitted from pixel 230G. Light 175B, whose hue has been altered by passing through the colored layer 131B, is emitted from pixel 230B.

[0084] Color display can be achieved by changing the hue of the light controlled by each pixel. To achieve color display, the color of the colored layer combined with the light-emitting element 170 may be not only a combination of red, green, and blue, but also a combination of yellow, cyan, and magenta. The color of the colored layer to be combined should be set appropriately according to the purpose or application.

[0085] [substrate] There are no major restrictions on the materials used for substrates 111 and 121. Depending on the purpose, the materials should be determined by considering factors such as the presence or absence of light transmission and heat resistance sufficient to withstand heat treatment. For example, glass substrates such as barium borosilicate glass and aluminoborosilicate glass, ceramic substrates, quartz substrates, and sapphire substrates can be used. Semiconductor substrates, flexible substrates, laminated films, and base films may also be used.

[0086] Examples of semiconductor substrates include semiconductor substrates made from silicon or germanium, or compound semiconductor substrates made from silicon carbide, silicon germanium, gallium arsenide, indium phosphide, zinc oxide, or gallium oxide. Furthermore, the semiconductor substrate may be a single-crystal semiconductor or a polycrystalline semiconductor.

[0087] Furthermore, in order to enhance the flexibility of the display device 100, flexible substrates, laminated films, base films, etc., may be used for the substrates 111 and 121.

[0088] Examples of materials that can be used for flexible substrates, laminated films, and base films include polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyacrylonitrile resin, acrylic resin, polyimide resin, polymethyl methacrylate resin, polycarbonate (PC) resin, polyethersulfone (PES) resin, polyamide resin (nylon, aramid, etc.), polysiloxane resin, cycloolefin resin, polystyrene resin, polyamide-imide resin, polyurethane resin, polyvinyl chloride resin, polyvinylidene chloride resin, polypropylene resin, polytetrafluoroethylene (PTFE) resin, ABS resin, and cellulose nanofiber.

[0089] By using the above material as the substrate, a lightweight display device can be provided. Furthermore, by using the above material as the substrate, a shock-resistant display device can be provided. Furthermore, by using the above material as the substrate, a damage-resistant display device can be provided.

[0090] The flexible substrates used for substrates 111 and 121 are preferable if they have a low coefficient of thermal expansion, as this suppresses deformation due to the environment. For example, the flexible substrates used for substrates 111 and 121 have a coefficient of thermal expansion of 1 × 10⁻⁶. -3 / K or less, 5×10 -5 / K or less, or 1 × 10 -5Any material with a thermal expansion coefficient of 0.00 / K or less should be used. In particular, aramid is suitable as a flexible substrate because of its low coefficient of thermal expansion.

[0091] [Conductive layer] Conductive materials that can be used for conductive layers such as the gate, source, and drain of transistors, as well as various wirings and electrodes that constitute display devices, include metal elements selected from aluminum, chromium, copper, silver, gold, platinum, tantalum, nickel, titanium, molybdenum, tungsten, hafnium (Hf), vanadium (V), niobium (Nb), manganese, magnesium, zirconium, beryllium, etc., alloys composed of the above metal elements, or alloys combining the above metal elements. Semiconductors such as polycrystalline silicon containing impurity elements such as phosphorus, and silicides such as nickel silicide may also be used. The method of forming the conductive material is not particularly limited, and various formation methods such as vapor deposition, CVD, sputtering, and spin coating can be used.

[0092] Furthermore, conductive materials that can be used in the conductive layer include oxygen-containing conductive materials such as indium tin oxide, indium oxide containing tungsten oxide, indium zinc oxide containing tungsten oxide, indium oxide containing titanium oxide, indium tin oxide containing titanium oxide, indium zinc oxide, and indium tin oxide with silicon oxide added. In addition, nitrogen-containing conductive materials such as titanium nitride, tantalum nitride, and tungsten nitride can also be used. Moreover, a laminated structure can be constructed by appropriately combining oxygen-containing conductive materials, nitrogen-containing conductive materials, and materials containing the aforementioned metal elements.

[0093] The conductive material that can be used for the conductive layer may be a single-layer structure or a laminated structure of two or more layers. For example, there is a single-layer structure of an aluminum layer containing silicon, a two-layer structure in which a titanium layer is laminated on an aluminum layer, a two-layer structure in which a titanium layer is laminated on a titanium nitride layer, a two-layer structure in which a tungsten layer is laminated on a titanium nitride layer, a two-layer structure in which a tungsten layer is laminated on a tantalum nitride layer, and a three-layer structure in which a titanium layer is laminated, an aluminum layer is laminated on the titanium layer, and then a titanium layer is formed on top of that. In addition, an aluminum alloy containing one or more elements selected from titanium, tantalum, tungsten, molybdenum, chromium, neodymium, and scandium may be used as the conductive material.

[0094] When the light-emitting element 170 is a top-emission type light-emitting element, it is preferable that the electrode 171 be formed using a conductive material that efficiently reflects the light emitted by the EL layer 172. The structure of the electrode 171 is not limited to a single layer, but may be a multi-layered structure. For example, when the electrode 171 is used as an anode, the layer in contact with the EL layer 172 may be a translucent layer such as indium tin oxide, and a highly reflective layer (aluminum, an aluminum alloy, or silver, etc.) may be provided in contact with that layer.

[0095] As conductive materials that reflect visible light, for example, metallic materials such as aluminum, gold, platinum, silver, nickel, tungsten, chromium, molybdenum, iron, cobalt, copper, or palladium, or alloys containing these metallic materials, can be used. Lanthanum, neodymium, or germanium may also be added to the above metallic materials and / or alloys. Furthermore, alloys containing aluminum (aluminum alloys) such as aluminum-titanium alloys, aluminum-nickel alloys, and aluminum-neodymium alloys, as well as silver-containing alloys such as silver-copper alloys, silver-palladium-copper alloys, and silver-magnesium alloys, can be used to form the film. Alloys containing silver and copper are preferred because of their high heat resistance. In addition, a metal film or alloy film and a metal oxide film may be laminated. For example, by laminating a metal film or metal oxide film so that it is in contact with an aluminum alloy film, oxidation of the aluminum alloy film can be suppressed. Other examples of metal films and metal oxide films include titanium and titanium oxide. Furthermore, as described above, a light-transmitting conductive film and a film made of a metallic material may be laminated. For example, a multilayer film of silver and indium tin oxide, or a multilayer film of a silver-magnesium alloy and indium tin oxide (ITO) can be used.

[0096] Furthermore, when the light-emitting element 170 is a bottom-emission structure (bottom-surface injection structure), a conductive material that transmits visible light may be used for electrode 171 and a conductive material that reflects visible light may be used for electrode 173. Alternatively, when the light-emitting element 170 is a dual-emission structure (double-sided injection structure) display device, a conductive material that transmits visible light may be used for both electrode 171 and electrode 173.

[0097] Furthermore, conductive oxides such as indium oxide, indium tin oxide, indium zinc oxide, zinc oxide, gallium-doped zinc oxide, or graphene can be used as the light-transmitting conductive material. Alternatively, oxide conductors can be applied as the light-transmitting conductive material. Alternatively, metallic materials such as gold, silver, platinum, magnesium, nickel, tungsten, chromium, molybdenum, iron, cobalt, copper, palladium, or titanium, or alloy materials containing such metallic materials, can be used. Alternatively, nitrides of such metallic materials (e.g., titanium nitride) may be used. When using metallic materials, alloy materials (or their nitrides), they should be thinned to a degree that allows for light transmission. In addition, a laminated film of the above materials can be used as a conductive layer. For example, using a laminated film of a silver-magnesium alloy and indium tin oxide is preferable because it can enhance conductivity. These can also be used for conductive layers of various wirings and electrodes that constitute a display device, and for conductive layers of display elements (conductive layers that function as pixel electrodes or common electrodes).

[0098] Here, we will explain oxide conductors, which are a type of metal oxide. In this specification, oxide conductors may be referred to as OC (Oxide Conductor). As an example of an oxide conductor, when an oxygen vacancy is formed in a metal oxide and hydrogen is added to the oxygen vacancy, a donor level is formed near the conduction band. As a result, the metal oxide becomes highly conductive and becomes a conductor. A metal oxide that has become conductive can be called an oxide conductor. In general, oxide semiconductors have a large energy gap and are therefore transparent to visible light. On the other hand, oxide conductors are metal oxides that have a donor level near the conduction band. Therefore, oxide conductors are less affected by absorption due to the donor level and have a transparency to visible light of a similar degree to that of oxide semiconductors.

[0099] [Insulating layer] Each insulating layer is made from a material selected from aluminum nitride, aluminum oxide, aluminum oxide nitride, aluminum oxide nitride, magnesium oxide, silicon nitride, silicon oxide, silicon oxide nitride, silicon oxide nitride, gallium oxide, germanium oxide, yttrium oxide, zirconium oxide, lanthanum oxide, neodymium oxide, hafnium oxide, tantalum oxide, aluminum silicate, etc., and is used as a single layer or in multiple layers. Alternatively, a material made by mixing multiple materials from oxide materials, nitride materials, oxide nitride materials, and nitride oxide materials may be used.

[0100] In this specification, "nitride oxide" refers to a compound with a higher nitrogen content than oxygen content. Similarly, "oxiditride" refers to a compound with a higher oxygen content than nitrogen content. The content of each element can be measured, for example, using Rutherford backscattering spectrometry (RBS).

[0101] In particular, the insulating layer 113 and insulating layer 213 are preferably formed using insulating materials that do not easily allow impurities to permeate. For example, insulating materials containing boron, carbon, nitrogen, oxygen, fluorine, magnesium, aluminum, silicon, phosphorus, chlorine, argon, gallium, germanium, yttrium, zirconium, lanthanum, neodymium, hafnium, or tantalum may be used in a single layer or in a laminated form. Examples of insulating materials that do not easily allow impurities to permeate include aluminum oxide, aluminum nitride, aluminum oxide nitride, aluminum oxide nitride, gallium oxide, germanium oxide, yttrium oxide, zirconium oxide, lanthanum oxide, neodymium oxide, hafnium oxide, tantalum oxide, and silicon nitride.

[0102] By using an insulating material that is less permeable to impurities in the insulating layer 113, the diffusion of impurities from the substrate 111 side can be suppressed, thereby improving the reliability of the transistor. By using an insulating material that is less permeable to impurities in the insulating layer 213, the diffusion of impurities from the insulating layer 114 side can be suppressed, thereby improving the reliability of the transistor.

[0103] Furthermore, heat-resistant organic materials such as polyimide, acrylic resin, benzocyclobutene resin, polyamide, and epoxy resin can be used as insulating layers that can function as planarization layers. In addition to the above organic materials, low dielectric constant materials (low-k materials), siloxane resins, PSG (phosphorus glass), BPSG (phosphorus boron glass), etc., can also be used. Multiple insulating layers formed from these materials may be laminated.

[0104] Siloxane-based resins refer to resins containing Si-O-Si bonds formed using siloxane-based materials as starting materials. Siloxane-based resins may use organic groups (e.g., alkyl or aryl groups) or fluoro groups as substituents. Furthermore, the organic groups may also contain fluoro groups.

[0105] Furthermore, chemical mechanical polishing (CMP) may be applied to the surface of the insulating layer or other components. By performing CMP treatment, surface irregularities of the sample can be reduced, thereby improving the coverage of the insulating layer and conductive layer formed thereafter.

[0106] [Colored layer] Materials that can be used for the colored layer include metal materials, resin materials, and resin materials containing pigments or dyes.

[0107] [Light blocking layer] Materials that can be used as a light-shielding layer include carbon black, titanium black, metals, metal oxides, and composite oxides containing solid solutions of multiple metal oxides. The light-shielding layer may be a film containing a resin material or a thin film of an inorganic material such as a metal. In addition, a laminated film containing the material for the colored layer can be used as the light-shielding layer. For example, a laminated structure can be used in which a film containing the material for a colored layer that transmits light of one color and a film containing the material for a colored layer that transmits light of another color are used. It is preferable to use the same materials for the colored layer and the light-shielding layer because it is possible to use the same equipment and simplify the process.

[0108] [About transistors] In one embodiment of the present invention, the structure of the transistors in the display device is not particularly limited. For example, they may be planar transistors or staggered transistors. They may also be top-gate or bottom-gate transistors. Alternatively, gate electrodes may be provided above and below the channel.

[0109] The transistors in the peripheral drive circuit and the transistors in the pixel circuit may have the same structure or different structures. All transistors in the peripheral drive circuit may have the same structure, or two or more different structures may be used in combination. Similarly, all transistors in the pixel circuit may have the same structure, or two or more different structures may be used in combination.

[0110] When one of the gate electrodes located above and below a channel is referred to as the "gate electrode," the other is called the "back gate electrode." Similarly, when one of the gate electrodes located above and below a channel is referred to as the "gate," the other is called the "back gate." In some cases, the gate electrode is referred to as the "front gate electrode." Likewise, the gate is sometimes referred to as the "front gate."

[0111] For example, electrode 221 of transistor 252 can function as a gate electrode. Also, electrode 226 of transistor 252 can function as a back gate electrode. Therefore, both insulating layer 210 and insulating layer 211 can function as gate insulating layers.

[0112] By providing a gate electrode and a back gate electrode, the semiconductor layer of the transistor can be electrically surrounded by the electric field generated from the gate electrode and the electric field generated from the back gate electrode. A transistor structure in which the semiconductor layer in which the channel is formed is electrically surrounded by the electric fields generated from the gate electrode and the back gate electrode can be called a Surrounded Channel (S-channel) structure.

[0113] The buck gate electrode can function similarly to the gate electrode. The potential of the buck gate electrode may be the same as the gate electrode, or it may be at ground potential or any other potential. Furthermore, by changing the potential of the buck gate electrode independently of the gate electrode, the threshold voltage of the transistor can be changed.

[0114] By providing a gate electrode and a back gate electrode, and furthermore, by setting them to the same potential, the region in the semiconductor layer where carriers flow becomes larger in the thickness direction, thus increasing the amount of carrier movement. As a result, the on-current of the transistor increases, and the field-effect mobility also increases.

[0115] Therefore, it is possible to design transistors that have a large on-current relative to their occupied area. In other words, the occupied area of ​​the transistor can be reduced relative to the required on-current. Thus, a highly integrated semiconductor device can be realized.

[0116] Furthermore, by using transistors with high on-current in the display device, even if the number of wires increases when the display device is made larger or higher resolution, it is possible to reduce the signal delay in each wire, thereby suppressing a decrease in display quality.

[0117] Furthermore, since the gate electrode and back gate electrode are formed from conductive layers, they have the function of preventing electric fields generated outside the transistor from acting on the semiconductor layer in which the channel is formed (particularly an electric field shielding function against static electricity). In a plan view, the electric field shielding function can be enhanced by making the back gate electrode larger than the semiconductor layer and covering the semiconductor layer with the back gate electrode.

[0118] The gate electrode and back gate electrode each have the function of shielding from external electric fields, so that charges such as charged particles generated above and below the transistor do not affect the channel formation region of the semiconductor layer. As a result, degradation during stress testing (for example, NGBT (Negative Gate Bias-Temperature) stress testing, also called "NBT" or "NBTS"), in which a negative voltage is applied to the gate, is suppressed. In addition, the gate electrode and back gate electrode can block the electric field generated from the drain electrode from acting on the semiconductor layer. Therefore, fluctuations in the on-current rise voltage caused by fluctuations in the drain voltage can be suppressed. This effect is particularly pronounced when potential is supplied to the gate electrode and back gate electrode.

[0119] Furthermore, transistors with a back gate electrode exhibit smaller threshold voltage fluctuations before and after PGBT (Positive Gate Bias-Temperature) stress testing (also known as "PBT" or "PBTS"), where a positive voltage is applied to the gate, compared to transistors without a back gate electrode.

[0120] BT stress tests, such as NGBT and PGBT, are a type of accelerated testing that allows for the rapid evaluation of transistor characteristic changes (aging) that occur over long-term use. In particular, the change in the transistor's threshold voltage before and after the BT stress test is an important indicator for examining reliability. The smaller the change in threshold voltage before and after the BT stress test, the more reliable the transistor is considered to be.

[0121] Furthermore, by having both a gate electrode and a back gate electrode, and by setting both to the same potential, the fluctuation in the threshold voltage is reduced. As a result, variations in electrical characteristics among multiple transistors are also reduced.

[0122] Furthermore, when light is incident from the back gate electrode side, forming the back gate electrode with a light-shielding conductive film prevents light from entering the semiconductor layer from the back gate electrode side. This prevents photodegradation of the semiconductor layer and prevents deterioration of electrical characteristics such as a shift in the transistor's threshold voltage.

[0123] [Semiconductor materials] There are no major restrictions on the crystallinity of the semiconductor material used for the semiconductor layer of a transistor. Amorphous semiconductors, crystalline semiconductors (microcrystalline semiconductors, polycrystalline semiconductors, single-crystal semiconductors, or semiconductors with crystalline regions in part) may be used. However, using a crystalline semiconductor is preferable because it suppresses the degradation of transistor characteristics.

[0124] Furthermore, for example, silicon and germanium can be used as semiconductor materials for the semiconductor layer of a transistor. Compound semiconductors such as silicon carbide, gallium arsenide, metal oxides, and nitride semiconductors, as well as organic semiconductors, can also be used.

[0125] For example, polycrystalline silicon (polysilicon) and amorphous silicon can be used as semiconductor materials for transistors. Additionally, oxide semiconductors, a type of metal oxide, can be used as semiconductor materials for transistors.

[0126] <Metal oxides> Here, we will explain metal oxides that can be used as oxide semiconductors.

[0127] The metal oxide used as the oxide semiconductor preferably contains at least indium or zinc. In particular, it is preferable that it contains indium and zinc. In addition, it is preferable that it contains aluminum, gallium, yttrium, tin, etc. Furthermore, it may contain one or more selected from boron, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, magnesium, cobalt, etc.

[0128] Here, we consider the case where the metal oxide is an In-M-Zn oxide containing indium, element M, and zinc. Element M can be aluminum, gallium, yttrium, or tin. Other elements that can be used for element M include boron, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, magnesium, and cobalt. However, it is sometimes permissible to use a combination of multiple of the aforementioned elements as element M.

[0129] In this specification, metal oxides containing nitrogen may also be collectively referred to as metal oxides. Furthermore, metal oxides containing nitrogen may also be called metal oxynitrides.

[0130] <Classification of crystal structures> First, we will explain the classification of crystal structures in oxide semiconductors using Figure 14A. Figure 14A is a diagram illustrating the classification of crystal structures in oxide semiconductors, specifically IGZO (a metal oxide containing In, Ga, and Zn).

[0131] As shown in Figure 14A, oxide semiconductors are broadly classified into "Amorphous," "Crystalline," and "Crystal." "Amorphous" includes completely amorphous semiconductors. "Crystalline" includes CAAC (c-axis-aligned crystalline), nc (nanocrystalline), and CAC (cloud-aligned composite). Note that single crystal, polycrystal, and completely amorphous semiconductors are excluded from the "Crystalline" classification. "Crystal" includes single crystal and polycrystal semiconductors.

[0132] The structure within the thick frame shown in Figure 14A represents an intermediate state between "Amorphous" and "Crystal," and belongs to a new boundary region (New crystalline phase). In other words, this structure can be described as being completely different from the energetically unstable "Amorphous" and "Crystal" states.

[0133] The crystal structure of a film or substrate can be evaluated using X-ray diffraction (XRD) spectroscopy. Figure 14B shows the XRD spectrum obtained by GIXD (Grazing-Incidence XRD) measurement of a CAAC-IGZO film classified as "Crystalline." The GIXD method is also known as the thin-film method or Seemann-Bohlin method. Hereafter, the XRD spectrum obtained by the GIXD measurement shown in Figure 14B may simply be referred to as the XRD spectrum in this specification. The composition of the CAAC-IGZO film shown in Figure 14B is approximately In:Ga:Zn = 4:2:3 [atomic ratio]. The thickness of the CAAC-IGZO film shown in Figure 14B is 500 nm.

[0134] In Figure 14(B), the horizontal axis represents 2θ [deg.] and the vertical axis represents intensity [au]. As shown in Figure 14B, the XRD spectrum of the CAAC-IGZO film shows a peak indicating clear crystallinity. Specifically, the XRD spectrum of the CAAC-IGZO film shows a peak indicating c-axis orientation near 2θ = 31°. As shown in Figure 14B, the peak near 2θ = 31° is asymmetrical with respect to the angle at which the peak intensity was detected.

[0135] Furthermore, the crystal structure of a film or substrate can be evaluated by the diffraction pattern (also called the nano-beam electron diffraction pattern) observed by nano-beam electron diffraction (NBED). The diffraction pattern of a CAAC-IGZO film is shown in Figure 14C. Figure 14C shows the diffraction pattern observed by NBED with the electron beam incident parallel to the substrate. The composition of the CAAC-IGZO film shown in Figure 14C is approximately In:Ga:Zn=4:2:3 [atomic ratio]. In nano-beam electron diffraction, electron diffraction is performed with a probe diameter of 1 nm.

[0136] As shown in Figure 14C, the diffraction pattern of the CAAC-IGZO film shows multiple spots indicating c-axis orientation.

[0137] <Oxide semiconductor structure> Note that when focusing on the crystal structure, oxide semiconductors may be classified differently from those shown in Figure 14A. For example, oxide semiconductors can be divided into single-crystal oxide semiconductors and other non-single-crystal oxide semiconductors. Examples of non-single-crystal oxide semiconductors include the aforementioned CAAC-OS and nc-OS. Non-single-crystal oxide semiconductors also include polycrystalline oxide semiconductors, pseudo-amorphous oxide semiconductors (a-like OS), and amorphous oxide semiconductors.

[0138] Here, we will explain the details of the CAAC-OS, nc-OS, and a-like OS mentioned above.

[0139] [CAAC-OS] CAAC-OS is an oxide semiconductor having multiple crystalline regions, the c-axis of which is oriented in a specific direction. This specific direction is the thickness direction of the CAAC-OS film, the normal direction to the surface on which the CAAC-OS film is formed, or the normal direction to the surface of the CAAC-OS film. A crystalline region is a region with periodic atomic arrangement. If we consider the atomic arrangement as a lattice arrangement, then a crystalline region is also a region with a aligned lattice arrangement. Furthermore, CAAC-OS has regions where multiple crystalline regions are connected in the ab-plane direction, and these regions may exhibit distortion. Distortion refers to a point in the connected region where the orientation of the lattice arrangement changes between a region with a aligned lattice arrangement and another region with a aligned lattice arrangement. In short, CAAC-OS is an oxide semiconductor that is c-axis oriented and does not exhibit clear orientation in the ab-plane direction.

[0140] Each of the multiple crystalline regions described above is composed of one or more minute crystals (crystals with a maximum diameter of less than 10 nm). When a crystalline region is composed of a single minute crystal, the maximum diameter of that crystalline region is less than 10 nm. When a crystalline region is composed of many minute crystals, the size of that crystalline region may be around several tens of nanometers.

[0141] Furthermore, in In-M-Zn oxides (where element M is one or more elements selected from aluminum, gallium, yttrium, tin, titanium, etc.), CAAC-OS tends to have a layered crystalline structure (also called a layered structure) consisting of layers containing indium (In) and oxygen (hereinafter referred to as the In layer) and layers containing element M, zinc (Zn), and oxygen (hereinafter referred to as the (M,Zn) layer). Note that indium and element M are mutually substitutable. Therefore, the (M,Zn) layer may contain indium. Also, the In layer may contain element M. Also, the In layer may contain Zn. This layered structure can be observed, for example, as a lattice image in high-resolution TEM images.

[0142] When structural analysis of a CAAC-OS film is performed using an XRD instrument, for example, out-of-plane XRD measurements using θ / 2θ scanning show a peak indicating c-axis orientation at 2θ = 31° or nearby. Note that the position of the c-axis orientation peak (value of 2θ) may vary depending on the type and composition of the metal elements constituting the CAAC-OS.

[0143] Furthermore, for example, multiple bright spots are observed in the electron diffraction pattern of a CAAC-OS film. These spots are observed at point-symmetric positions with respect to the incident electron beam spot (also called the direct spot) that passed through the sample.

[0144] When the crystal region is observed from the specific direction described above, the lattice arrangement within that crystal region is based on a hexagonal lattice, but the unit cell is not necessarily a regular hexagon and may be non-regular hexagonal. Furthermore, the strain may have lattice arrangements such as pentagons or heptagons. Moreover, in CAAC-OS, clear grain boundaries cannot be observed even near the strain. In other words, it can be seen that the formation of grain boundaries is suppressed by the strain in the lattice arrangement. This is thought to be because CAAC-OS can tolerate strain due to the fact that the arrangement of oxygen atoms is not dense in the ab-plane direction, and the bond distance between atoms changes due to the substitution of metal atoms.

[0145] A crystal structure in which clear grain boundaries are observed is called a polycrystal. Grain boundaries act as recombination centers, trapping carriers and potentially causing a decrease in transistor on-current and field-effect mobility. Therefore, CAAC-OS, in which clear grain boundaries are not observed, is one of the crystalline oxides with a suitable crystal structure for the semiconductor layer of a transistor. In addition, a structure containing Zn is preferred for the composition of CAAC-OS. For example, In-Zn oxide and In-Ga-Zn oxide are preferred because they suppress the generation of grain boundaries more than In oxide.

[0146] CAAC-OS is an oxide semiconductor with high crystallinity and no clearly defined grain boundaries. Therefore, CAAC-OS is less susceptible to the decrease in electron mobility caused by grain boundaries. Furthermore, since the crystallinity of oxide semiconductors can decrease due to the inclusion of impurities and the generation of defects, CAAC-OS can be said to be an oxide semiconductor with few impurities and defects (such as oxygen vacancies). Consequently, oxide semiconductors containing CAAC-OS have stable physical properties. Therefore, oxide semiconductors containing CAAC-OS are heat-resistant and highly reliable. In addition, CAAC-OS is stable even at high temperatures (so-called thermal budget) during the manufacturing process. Therefore, using CAAC-OS in OS transistors allows for greater flexibility in the manufacturing process.

[0147] [nc-OS] nc-OS exhibits periodicity in atomic arrangement in minute regions (e.g., regions between 1 nm and 10 nm, particularly between 1 nm and 3 nm). In other words, nc-OS contains minute crystals. These minute crystals are also called nanocrystals because their size is, for example, between 1 nm and 10 nm, particularly between 1 nm and 3 nm. Furthermore, nc-OS shows no regularity in crystal orientation between different nanocrystals. Therefore, no orientation is observed throughout the film. Consequently, depending on the analytical method, nc-OS may be indistinguishable from a-like OS or amorphous oxide semiconductors. For example, when structural analysis of an nc-OS film is performed using an XRD instrument, no peaks indicating crystallinity are detected in out-of-plane XRD measurements using θ / 2θ scanning. Also, when electron diffraction (also called limited-field electron diffraction) is performed on an nc-OS film using an electron beam with a probe diameter larger than that of the nanocrystals (e.g., 50 nm or larger), a diffraction pattern resembling a halo pattern is observed. On the other hand, when electron diffraction (also called nanobeam electron diffraction) is performed on an nc-OS film using an electron beam with a probe diameter close to or smaller than the size of the nanocrystal (for example, 1 nm to 30 nm), an electron diffraction pattern may be obtained in which multiple spots are observed within a ring-shaped region centered on a direct spot.

[0148] [a-like OS] a-like OS is an oxide semiconductor having a structure between nc-OS and amorphous oxide semiconductors. a-like OS has porous or low-density regions. In other words, a-like OS has lower crystallinity compared to nc-OS and CAAC-OS. Also, a-like OS has a higher hydrogen concentration in the film compared to nc-OS and CAAC-OS.

[0149] <Oxide semiconductor structure> Next, we will explain the details of CAC-OS mentioned above. Note that CAC-OS refers to the material composition.

[0150] [CAC-OS] CAC-OS is a material composition in which, for example, the elements constituting the metal oxide are unevenly distributed in sizes of 0.5 nm to 10 nm, preferably 1 nm to 3 nm, or close to that size. In the following, a state in which one or more metal elements are unevenly distributed in a metal oxide, and the regions containing these metal elements are mixed in sizes of 0.5 nm to 10 nm, preferably 1 nm to 3 nm, or close to that size, is also referred to as a mosaic or patchy state.

[0151] Furthermore, CAC-OS is a composite metal oxide having a mosaic-like structure formed by the separation of the material into a first region and a second region, with the first region distributed within the film (hereinafter also referred to as a cloud-like structure). In other words, CAC-OS is a composite metal oxide having a structure in which the first region and the second region are mixed.

[0152] Here, the atomic ratios of In, Ga, and Zn to the metal elements constituting the CAC-OS in In-Ga-Zn oxide are denoted as [In], [Ga], and [Zn], respectively. For example, in the CAC-OS of In-Ga-Zn oxide, the first region is the region where [In] is greater than the [In] in the composition of the CAC-OS film. The second region is the region where [Ga] is greater than the [Ga] in the composition of the CAC-OS film. Alternatively, for example, the first region is the region where [In] is greater than the [In] in the second region, and [Ga] is smaller than the [Ga] in the second region. The second region is the region where [Ga] is greater than the [Ga] in the first region, and [In] is smaller than the [In] in the first region.

[0153] Specifically, the first region described above is a region whose main components are indium oxide, indium zinc oxide, etc. The second region described above is a region whose main components are gallium oxide, gallium zinc oxide, etc. In other words, the first region can be rephrased as a region whose main component is In. Similarly, the second region can be rephrased as a region whose main component is Ga.

[0154] Furthermore, a clear boundary may not be observed between the first region and the second region described above.

[0155] For example, in the case of CAC-OS in In-Ga-Zn oxide, EDX mapping obtained using energy dispersive X-ray spectroscopy (EDX) confirms that it has a structure in which regions mainly composed of In (first region) and regions mainly composed of Ga (second region) are unevenly distributed and mixed.

[0156] When CAC-OS is used in a transistor, the conductivity due to the first region and the insulation due to the second region work complementaryly to give CAC-OS a switching function (on / off function). In other words, CAC-OS has conductive function in part of the material, insulating function in part of the material, and semiconductor function as a whole. By separating the conductive function and the insulating function, both functions can be maximized. Therefore, by using CAC-OS in a transistor, a high on-current (I) can be achieved. on This enables high field-effect mobility (μ) and good switching operation.

[0157] Oxide semiconductors can take on diverse structures, each possessing different properties. One embodiment of the present invention may include two or more of the following: amorphous oxide semiconductors, polycrystalline oxide semiconductors, a-like OS, CAC-OS, nc-OS, and CAAC-OS.

[0158] <Transistors containing oxide semiconductors> Next, we will explain the case where the above oxide semiconductor is used in a transistor.

[0159] By using the above-mentioned oxide semiconductor in transistors, transistors with high field-effect mobility can be realized. Furthermore, highly reliable transistors can be achieved.

[0160] It is preferable to use an oxide semiconductor with a low carrier concentration for the channel formation region of the transistor. For example, the carrier concentration in the channel formation region of the oxide semiconductor is 1×10 17 cm -3 or less, preferably 1×10 15 cm -3 or less, more preferably 1×10 13 cm -3 or less, still more preferably 1×10 11 cm -3 or less, even more preferably 1×10 10 cm -3 or less, and 1×10 -9 cm -3 or more. When reducing the carrier concentration of the oxide semiconductor film, the impurity concentration in the oxide semiconductor film may be reduced and the density of defect levels may be reduced. In this specification and the like, a low impurity concentration and a low density of defect levels are referred to as high purity intrinsic or substantially high purity intrinsic. In some cases, an oxide semiconductor with a low carrier concentration may be referred to as a high purity intrinsic or substantially high purity intrinsic oxide semiconductor.

[0161] [[ID=,28]]In addition, since the oxide semiconductor film having high purity intrinsic or substantially high purity intrinsic has a low density of defect levels, the trap level density may also be low.

[0162] In addition, the charge trapped in the trap level of the oxide semiconductor has a long time required to disappear and may behave like a fixed charge. Therefore, the electrical characteristics of a transistor in which a channel formation region is formed in an oxide semiconductor having a high trap level density may become unstable.

[0163] Therefore, in order to stabilize the electrical characteristics of the transistor, it is effective to reduce the impurity concentration in the oxide semiconductor. In addition, in order to reduce the impurity concentration in the oxide semiconductor, it is preferable to also reduce the impurity concentration in the adjacent film. Examples of impurities include hydrogen, nitrogen, alkali metals, alkaline earth metals, iron, nickel, silicon, and the like.

[0164] <Impurity> Here, we will explain the effects of various impurities in oxide semiconductors.

[0165] In oxide semiconductors, the presence of silicon or carbon, which are Group 14 elements, leads to the formation of defect levels in the oxide semiconductor. Therefore, the concentrations of silicon and carbon in the channel formation region of the oxide semiconductor and the concentrations of silicon or carbon near the interface with the channel formation region of the oxide semiconductor (concentrations obtained by secondary ion mass spectrometry (SIMS)) are measured in 2 × 10⁻¹⁰ units. 18 atoms / cm 3 The following is preferably 2 × 10 17 atoms / cm 3 The following applies:

[0166] Furthermore, if an oxide semiconductor contains alkali metals or alkaline earth metals, it may form defect levels and generate carriers. Therefore, transistors using oxide semiconductors containing alkali metals or alkaline earth metals tend to exhibit normally-on characteristics. For this reason, the concentration of alkali metals or alkaline earth metals in the channel formation region of the oxide semiconductor obtained by SIMS should be set to 1 × 10⁻⁶. 18 atoms / cm 3 The following is preferably 2 × 10 16 atoms / cm 3 Do the following:

[0167] Furthermore, in oxide semiconductors, the presence of nitrogen generates electrons, which act as carriers, increasing the carrier concentration and making it easier for the semiconductor to become n-type. As a result, transistors using oxide semiconductors containing nitrogen tend to exhibit normally-on characteristics. Alternatively, the presence of nitrogen in oxide semiconductors can lead to the formation of trap levels. As a result, the electrical properties of the transistor may become unstable. For this reason, the nitrogen concentration in the channel formation region of oxide semiconductors obtained by SIMS should be set to 5 × 10⁻⁶. 19 atoms / cm 3 Less than 5 × 10 18 atoms / cm 3More preferably 1 × 10 18 atoms / cm 3 More preferably 5 × 10 17 atoms / cm 3 Do the following:

[0168] Furthermore, hydrogen contained in oxide semiconductors can react with oxygen bonded to metal atoms to form water, potentially creating oxygen vacancies. When hydrogen fills these oxygen vacancies, electrons, which act as carriers, may be generated. Additionally, some of the hydrogen can combine with oxygen bonded to metal atoms to generate electrons. Therefore, transistors using oxide semiconductors containing hydrogen tend to exhibit normally-on characteristics. For this reason, it is preferable to minimize the amount of hydrogen in the channel formation region of the oxide semiconductor. Specifically, in the channel formation region of the oxide semiconductor, the hydrogen concentration obtained by SIMS should be 1 × 10⁻⁶. 20 atoms / cm 3 Less than 5 × 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.

[0169] By using an oxide semiconductor with sufficiently reduced impurities in the channel formation region of a transistor, stable electrical characteristics can be provided.

[0170] <Other semiconductor materials> The semiconductor materials that can be used for the semiconductor layer of a transistor are not limited to the metal oxides mentioned above. Semiconductor materials with a band gap (semiconductor materials that are not zero-gap semiconductors) may also be used as the semiconductor layer. For example, it is preferable to use semiconductors of single elements such as silicon, compound semiconductors such as gallium arsenide, or layered materials that function as semiconductors (also called atomic layer materials or two-dimensional materials). In particular, it is preferable to use layered materials that function as semiconductors as the semiconductor material.

[0171] In this specification, the term "layered material" refers to a group of materials having a layered crystalline structure. A layered crystalline structure is a structure in which layers formed by covalent or ionic bonds are stacked via weaker bonds than covalent or ionic bonds, such as van der Waals forces. Layered materials have high electrical conductivity within a unit layer, that is, high two-dimensional electrical conductivity. By using a material that functions as a semiconductor and has high two-dimensional electrical conductivity in the channel formation region, a transistor with a large on-current can be provided.

[0172] Layered materials include graphene, silicene, and chalcogenides. Chalcogenides are compounds containing chalcogens. Chalcogens are a general term for elements belonging to Group 16, and include oxygen, sulfur, selenium, tellurium, polonium, and livermorium. Examples of chalcogenides include transition metal chalcogenides and Group 13 chalcogenides.

[0173] For the semiconductor layer of the transistor, it is preferable to use, for example, a transition metal chalcogenide that functions as a semiconductor. Specific examples of transition metal chalcogenides applicable as semiconductor layers include molybdenum sulfide (typically MoS2), molybdenum selenide (typically MoSe2), molybdenum tellurium (typically MoTe2), tungsten sulfide (typically WS2), tungsten selenide (typically WSe2), tungsten tellurium (typically WTe2), hafnium sulfide (typically HfS2), hafnium selenide (typically HfSe2), zirconium sulfide (typically ZrS2), and zirconium selenide (typically ZrSe2).

[0174] <Example of manufacturing method> An example of a method for manufacturing the display device 100 will be explained with reference to the drawings. In this embodiment, the manufacturing method will be explained focusing on the display area 235.

[0175] Furthermore, insulating layers, semiconductor layers, and conductive layers for forming electrodes and wiring that constitute the display device can be formed using methods such as sputtering, chemical vapor deposition (CVD), vacuum deposition, pulsed laser deposition (PLD), atomic layer deposition (ALD), and plasma enhanced ALD (PEALD). For CVD methods, plasma chemical vapor deposition (PECVD) or thermal CVD may also be used. As an example of thermal CVD, metal-organic chemical vapor deposition (MOCVD) may be used.

[0176] Furthermore, insulating layers, semiconductor layers, and conductive layers for forming electrodes and wiring that constitute the display device may be formed by methods such as spin coating, dip coating, spray coating, inkjet printing, dispensing, screen printing, offset printing, slit coating, roll coating, curtain coating, and knife coating.

[0177] PECVD (Polymer-Emission Vapor Deposition) yields high-quality films at relatively low temperatures. Using non-plasma deposition methods such as MOCVD (Modified Oxide Vapor Deposition), ALD (Automated Lamination), or thermal CVD (Chemical Vapor Deposition) reduces damage to the deposition surface. For example, wiring, electrodes, and components (transistors, capacitive elements, etc.) in semiconductor devices can be charged up by receiving charge from the plasma. This accumulated charge can destroy the wiring, electrodes, and components in the semiconductor device. On the other hand, non-plasma deposition methods avoid this plasma damage, resulting in higher yields for semiconductor devices. Furthermore, the absence of plasma damage during deposition allows for the production of films with fewer defects.

[0178] Unlike film deposition methods where particles emitted from a target or other source are deposited, CVD and ALD methods form films through reactions on the surface of the workpiece. Therefore, they are less affected by the shape of the workpiece and offer good step-level coverage. In particular, the ALD method is suitable for coating the surface of openings with high aspect ratios due to its excellent step-level coverage and uniform thickness. However, because the ALD method has a relatively slow deposition rate, it is sometimes preferable to use it in combination with other film deposition methods that have a faster deposition rate, such as the CVD method.

[0179] CVD and ALD methods allow control over the composition of the resulting film by adjusting the flow rate ratio of the source gases. For example, CVD and ALD methods can deposit films of any composition by changing the flow rate ratio of the source gases. Furthermore, CVD and ALD methods can deposit films with continuously changing compositions by varying the flow rate ratio of the source gases during film deposition. When depositing films while varying the flow rate ratio of the source gases, the film deposition time can be reduced compared to using multiple deposition chambers by eliminating the time required for transport and pressure adjustment. Therefore, it may be possible to increase the productivity of semiconductor devices.

[0180] Furthermore, when forming a film using the ALD method, it is preferable to use a chlorine-free gas as the material gas.

[0181] Furthermore, when forming oxide semiconductors by sputtering, the chamber in the sputtering apparatus is kept under high vacuum (5 × 10) using an adsorption-type vacuum pump such as a cryopump to remove as much water and other impurities as possible from the oxide semiconductor. -7 Pa to 1 × 10 -4 It is preferable to evacuate the chamber to approximately Pa. In particular, when the sputtering apparatus is in standby mode, the partial pressure of gas molecules corresponding to H2O (gas molecules corresponding to m / z=18) in the chamber should be 1 × 10⁻⁶. -4 It is preferable to keep it below Pa, 5 × 10 -5 It is more preferable to keep the temperature below Pa. The film deposition temperature is preferably RT or above 500°C, more preferably RT or above 300°C, and even more preferably RT or above 200°C.

[0182] Furthermore, it is necessary to purify the sputtering gas. For example, by using oxygen and argon gases used as sputtering gases that have been purified to a dew point of -40°C or lower, preferably -80°C or lower, more preferably -100°C or lower, and more preferably -120°C or lower, it is possible to prevent moisture and other substances from being incorporated into the oxide semiconductor film as much as possible.

[0183] Furthermore, when forming insulating layers, conductive layers, or semiconductor layers using the sputtering method, oxygen can be supplied to the layer being formed by using a sputtering gas containing oxygen. The more oxygen contained in the sputtering gas, the more oxygen is likely to be supplied to the layer being formed.

[0184] When processing the layers (thin films) that make up the display device, processing can be done using methods such as photolithography. Alternatively, island-like layers may be formed by a film deposition method using a shielding mask. Alternatively, the layers may be processed by methods such as nanoimprint, sandblasting, or lift-off. Photolithography methods include a method in which a resist mask is formed on the layer (thin film) to be processed, a part of the layer (thin film) is selectively removed using the resist mask as a mask, and then the resist mask is removed; and a method in which a photosensitive layer is deposited, and then exposed and developed to process the layer into the desired shape.

[0185] In photolithography, when using light, the light used for exposure can be, for example, i-line (wavelength 365 nm), g-line (wavelength 436 nm), h-line (wavelength 405 nm), or a mixture thereof. Other options include ultraviolet light, KrF laser light, or ArF laser light. Exposure may also be performed using immersion lithography. Furthermore, extreme ultraviolet (EUV) light or X-rays may be used as the light source for exposure. An electron beam can also be used instead of light for exposure. Using extreme ultraviolet light, X-rays, or an electron beam is preferable because it allows for extremely fine processing. Note that a photomask is not required when exposure is performed by scanning a beam such as an electron beam.

[0186] Dry etching and wet etching methods can be used to remove (etch) the layers (thin films). These etching methods may also be used in combination.

[0187] The display device 100 shown in this embodiment is manufactured by combining a first element substrate 151 (see Figure 8(B)) and a second element substrate 152 (see Figure 11(C)).

[0188] [First element substrate 151] The method for manufacturing the first element substrate 151 will now be described.

[0189] [Process A1] An insulating layer 112 and an insulating layer 113 are formed on the substrate 111 (see Figure 2A). It is preferable that at least one of the insulating layer 112 and the insulating layer 113 be made of a material that is impermeable to impurities such as hydrogen and water.

[0190] [Process A2] Next, electrodes 221 are formed on the insulating layer 113. The electrodes 221 can be formed by depositing a conductive film, forming a resist mask, etching the conductive film, and then removing the resist mask.

[0191] [Process A3] Next, an insulating layer 211 is formed on the insulating layer 113 and the electrode 221. As the insulating layer 211, an inorganic insulating film such as silicon nitride film, silicon oxide nitride film, silicon oxide film, silicon nitride film, aluminum oxide film, or aluminum nitride film can be used. Alternatively, a hafnium oxide film, yttrium oxide film, zirconium oxide film, gallium oxide film, tantalum oxide film, magnesium oxide film, lanthanum oxide film, cerium oxide film, and neodymium oxide film may be used. Furthermore, two or more of the above insulating films may be stacked and used.

[0192] Inorganic insulating films are more dense and have higher barrier properties the higher the deposition temperature, so it is preferable to form them at high temperatures. The substrate temperature during deposition of the inorganic insulating film is preferably between room temperature (25°C) and 350°C, and more preferably between 100°C and 300°C.

[0193] Furthermore, when an oxide semiconductor is used for the semiconductor layer 231, it is preferable that the insulating layer having a region in contact with the semiconductor layer 231 is an insulating layer that releases oxygen upon heating (hereinafter also referred to as an "insulating layer containing excess oxygen"). Therefore, when an oxide semiconductor is used for the semiconductor layer 231, it is preferable that the insulating layer 211 is an insulating layer containing excess oxygen.

[0194] In this specification, oxygen released from the layer by heating is referred to as "excess oxygen." An insulating layer containing excess oxygen is subjected to a TDS analysis performed at a surface temperature of 100°C to 700°C, preferably 100°C to 500°C, and the amount of oxygen removed, converted to oxygen atoms, is 1.0 × 10⁻¹⁶. 18 atoms / cm 3 The above is 1.0 × 10 19 atoms / cm 3 The above, or 1.0 × 10 20 atoms / cm 3 In some cases, the number may be greater than this.

[0195] [Process A4] Next, a semiconductor layer 231 is formed. In this embodiment, an oxide semiconductor layer is formed as the semiconductor layer 231. The oxide semiconductor layer can be formed by depositing an oxide semiconductor film, forming a resist mask, etching the oxide semiconductor film, and then removing the resist mask.

[0196] The substrate temperature during the deposition of the oxide semiconductor film is preferably 350°C or lower, more preferably between room temperature and 200°C, and even more preferably between room temperature and 130°C.

[0197] Oxide semiconductor films can be deposited by sputtering, for example, using either an inert gas and / or oxygen gas as the sputtering gas. There are no particular limitations on the oxygen gas flow rate ratio (oxygen partial pressure) during the deposition of oxide semiconductor films. However, when obtaining transistors with high field-effect mobility, the oxygen flow rate ratio (oxygen partial pressure) during the deposition of oxide semiconductor films is preferably 0% to 30%, more preferably 5% to 30%, and even more preferably 7% to 15%.

[0198] The oxide semiconductor film preferably contains at least indium or zinc. It is particularly preferable that it contains both indium and zinc.

[0199] The oxide semiconductor preferably has an energy gap of 2 eV or more, more preferably 2.5 eV or more, and even more preferably 3 eV or more. By using an oxide semiconductor with a wide energy gap in this way, the off-current of the transistor can be reduced.

[0200] In particular, semiconductor materials with an energy gap of 2.5 eV or higher are preferred because they have high transmittance of visible light.

[0201] Oxide semiconductor films can be formed by sputtering. Other methods such as PLD, PECVD, thermal CVD, ALD, and vacuum deposition may also be used.

[0202] [Process A5] Next, electrodes 224a, 224b, and wiring 125 are formed (see Figure 2B). Electrodes 224a, 224b, and wiring 125 can be formed by depositing a conductive film, forming a resist mask, etching the conductive film, and then removing the resist mask. Electrodes 224a and 224b are electrically connected to the semiconductor layer 231, respectively.

[0203] Furthermore, when forming electrodes 224a and 224b, a portion of the semiconductor layer 231 not covered by the resist mask may be thinned by etching.

[0204] [Process A6] Next, an insulating layer 210 is formed. It is preferable to use an oxide insulating layer such as a silicon oxide layer or silicon oxynitride layer formed in an oxygen-containing atmosphere as the insulating layer 210. By forming the oxide insulating layer in an oxygen-containing atmosphere, an insulating layer containing excess oxygen can be obtained.

[0205] [Process A7] Next, an electrode 226 is formed on the insulating layer 210. The electrode 226 has a region that overlaps with the semiconductor layer 231. In this way, the transistor 251 can be formed. Although not shown in the figures, the transistor 252 is formed in the same manner.

[0206] [Process A8] Next, an insulating layer 213 is formed (see Figure 2C). It is preferable that the insulating layer 213 be formed of an insulating material that does not easily diffuse or permeate oxygen, such as silicon nitride.

[0207] If the insulating layer 210 is an insulating layer containing excess oxygen, oxygen can be efficiently supplied to the oxide semiconductor layer by performing a heat treatment while an insulating film that does not easily diffuse or permeate oxygen is laminated on top of it. As a result, oxygen vacancies in the oxide semiconductor layer and defects at the interface between the oxide semiconductor layer and the insulating layer 210 can be repaired, and defect levels can be reduced. This makes it possible to realize an extremely reliable transistor. Furthermore, by using this transistor in a display device, the reliability of the display device can be improved.

[0208] [Process A9] Next, an insulating layer 114 is formed. Since the insulating layer 114 is the layer to be formed on the display element that will be formed later, it is preferable that it functions as a planarization layer.

[0209] [Process A10] Next, openings 161 reaching the electrode 224a are formed in the insulating layer 114, insulating layer 213, and insulating layer 210.

[0210] [Process A11] Next, electrodes 171 are formed on the insulating layer 114 (see Figures 3A and 3B). Figure 3A is a schematic perspective view showing structures provided above the insulating layer 114. To make the explanation disclosed in this embodiment easier to understand, some components are omitted from Figure 3A. For example, components located below the electrodes 171 are omitted. The same applies to Figures 4A, 5A, 6A, 7A1, 7A2, 8A, and 9A, which will be described later.

[0211] Furthermore, in drawings and other materials, arrows indicating the X, Y, and Z directions may be included. In this specification, the "X direction" refers to the direction along the X-axis, and unless explicitly stated, there is no distinction between forward and reverse directions. The same applies to the "Y direction" and "Z direction." Also, the X, Y, and Z directions are directions that intersect each other. More specifically, the X, Y, and Z directions are directions that are orthogonal to each other. In this specification, one of the X, Y, or Z directions may be referred to as the "first direction" or "first direction." Another may be referred to as the "second direction" or "second direction." The remaining one may be referred to as the "third direction" or "third direction." In Figure 3, the direction perpendicular to the surface of the substrate 111 is defined as the Z direction.

[0212] Figure 3B is a schematic cross-sectional view of the XZ plane, which overlaps with regions F1 and F2 shown by dashed lines in Figure 3A, as seen in the Y direction. Electrode 171 is electrically connected to electrode 224a.

[0213] The electrode 171 is formed using a conductive material that reflects visible light. Furthermore, when the electrode 171 is used as an anode, it can be constructed as a laminated structure of, for example, ITO and silver. Alternatively, it can be constructed as a laminated structure with silver sandwiched between two layers of ITO.

[0214] [Process A12] Next, the EL layer 172 is formed. In this embodiment, the EL layer 172 is formed of organic EL. The EL layer 172 can be formed by methods such as vapor deposition, coating, printing, or ejection. It is preferable that the steps performed after the formation of the EL layer 172 are carried out so that the temperature applied to the EL layer 172 is below the heat resistance temperature of the EL layer 172.

[0215] [Process A13] Next, electrode 173 is formed. Electrode 173 is formed using a conductive material that transmits visible light. Furthermore, if electrode 173 is used as a cathode, it can be formed as a laminated structure of, for example, lithium fluoride and ITO.

[0216] [Process A14] Next, a resist mask 179 is formed on the electrode 173 (see Figures 4A and 4B). Figure 4A is a schematic perspective view showing the state after the resist mask 179 has been formed on the electrode 173. Figure 4B is a schematic cross-sectional view of the XZ plane, which overlaps with areas F1 and F2 shown by dashed lines in Figure 4A, as seen in the Y direction.

[0217] [Process A15] Next, a resist mask is used to selectively remove parts of electrode 171, EL layer 172, and electrode 173 (see Figures 5A and 5B). Figure 5A is a schematic perspective view showing the state after etching. Figure 5B is a schematic cross-sectional view of the XZ plane, which overlaps with areas F1 and F2 shown by dashed lines in Figure 5A, as seen in the Y direction.

[0218] The electrodes 171, EL layer 172, and electrode 173 can be removed (etched) using methods such as dry etching or wet etching. Alternatively, different etching methods may be used in combination. It is preferable to etch the electrodes 171, EL layer 172, and electrode 173 continuously (in a single step). By etching the electrodes 171, EL layer 172, and electrode 173 continuously, the formation of a resist mask for each layer becomes unnecessary, thereby increasing productivity.

[0219] Furthermore, depending on the etching conditions, the sides of electrode 171, EL layer 172, and electrode 173 can be made to nearly coincide. By making the sides of electrode 171, EL layer 172, and electrode 173 nearly coincide, the coverage of the insulating layer and other components applied in a later process can be improved, which is preferable.

[0220] [Process A16] Next, the resist mask 179 is removed (see Figures 6A and 6B). In this way, the light-emitting element 170 is formed. Figure 6A is a schematic perspective view showing the light-emitting element 170 formed by the etching process. Figure 6B is a schematic cross-sectional view of the XZ plane, which overlaps with parts F1 and F2 shown by dashed lines in Figure 6A, as seen in the Y direction.

[0221] By forming the light-emitting element 170 through etching using a resist mask, electrical interference between adjacent light-emitting layers can be prevented without the use of partitions. Therefore, the formation of partitions is unnecessary, which increases the productivity of the display device. Furthermore, because partitions are unnecessary, improvements in pixel aperture ratio, higher resolution, and miniaturization can be achieved.

[0222] Furthermore, according to one aspect of the present invention, by selectively and collectively removing a portion of each of the electrode 171 that functions as an anode, the EL layer 172, and the electrode 173 that functions as a cathode, it is possible to create different types of light-emitting elements that function as pixels. Therefore, it is possible to manufacture light-emitting elements without using a metal mask, or by reducing the amount of metal mask used, thereby increasing the productivity of display devices.

[0223] For example, when forming light-emitting elements 170 using a metal mask, it is difficult to make the distance between two adjacent light-emitting elements 170 20 μm or less due to dimensional accuracy constraints. According to one aspect of the present invention, the distance between two adjacent light-emitting elements 170 can be made 20 μm or less. Specifically, the distance between two adjacent light-emitting elements 170 can be made 0.5 μm or more and 15 μm or less, preferably 0.5 μm or more and 10 μm or less, and more preferably 0.5 μm or more and 5 μm or less. Therefore, improvements in pixel aperture ratio, higher resolution, and miniaturization can be achieved.

[0224] [Process A17] Next, an insulating layer 115 is formed to cover the light-emitting element 170 (see Figure 7B). It is preferable to use a material that does not easily absorb impurities such as water and hydrogen for the insulating layer 115. This allows the insulating layer 115 to function as a barrier film. This configuration effectively suppresses the diffusion of impurities from the outside to the light-emitting element 170 and the transistor, enabling the realization of a highly reliable display device.

[0225] As the insulating layer 115, for example, a laminated structure of an aluminum oxide (AlOx) film and a silicon nitride (SiNy) film on the aluminum oxide film, or a laminated structure of an oxide semiconductor (e.g., IGZO) and an aluminum oxide (AlOx) film on the IGZO film can be used. The aluminum oxide film, silicon nitride film, and oxide semiconductor film can be formed using ALD, CVD, or sputtering methods, respectively.

[0226] Figures 7A1 and 7A2 are schematic perspective views showing the electrode 117, which will be described later, mounted on the light-emitting element 170. Figure 7B is a schematic cross-sectional view of the XZ plane, which overlaps with parts F1 and F2 shown by dashed lines in Figure 7A1, as seen in the Y direction.

[0227] [Process A18] Next, an insulating layer 116 is formed on the insulating layer 115. Preferably, the insulating layer 116 functions as a planarizing layer.

[0228] Furthermore, CMP treatment may be performed on the surface of the insulating layer 116. By performing CMP treatment on the surface of the insulating layer 116, surface irregularities can be reduced, thereby improving the coverage of the insulating layer and conductive layer that are formed thereafter.

[0229] [Process A19] Next, electrodes 117 are formed so as to be embedded in the insulating layers 115 and 116. Electrodes 117 are provided for each light-emitting element 170 and are electrically connected to electrodes 173. The number of electrodes 117 provided for each light-emitting element 170 is not limited to one. As shown in Figure 7A2, multiple electrodes 117 may be provided for a single light-emitting element 170.

[0230] [Process A20] Next, a conductive layer 118 is formed on the insulating layer 116 and the electrode 117 (see Figures 8A and 8B). Figure 8A is a schematic perspective view showing the conductive layer 118 on the light-emitting element 170. Figure 8B is a schematic cross-sectional view of the XZ plane, which overlaps with parts F1 and F2 shown by dashed lines in Figure 8A, as seen in the Y direction.

[0231] The conductive layer 118 is electrically connected to the electrodes 173 of the multiple light-emitting elements 170 and functions as a common electrode. Furthermore, by forming the conductive layer 118 from a light-transmitting conductive material, the light 175 emitted by the light-emitting elements 170 can be extracted without being blocked. Therefore, the conductive layer 118 can be provided covering the light-emitting elements 170. In other words, the conductive layer 118 can be provided covering the entire display area 235.

[0232] Furthermore, the conductive layer 118 functions as a cathode auxiliary conductive layer. By providing the conductive layer 118, the potential variation of the cathode (electrode 173) across the entire display area 235 is reduced, and a uniform light emission intensity is obtained. Therefore, the display quality of the display device can be improved.

[0233] In this manner, the first element substrate 151 can be fabricated.

[0234] [Variation 1] Figure 9 shows a modified example of the first element substrate 151. In the first element substrate 151, instead of the conductive layer 118, wiring 119 may be provided on the insulating layer 116 and the electrode 117. Figure 9A is a schematic perspective view showing the state in which wiring 119 is provided on the light-emitting element 170. Figure 9B is a schematic cross-sectional view of the XZ plane, which overlaps with parts F1 and F2 shown by dashed lines in Figure 9A, as seen in the Y direction.

[0235] The wiring 119 can be formed using a conductive material that is transparent or light-shielding. When the wiring 119 is formed using a light-shielding material, it is preferable to arrange the wiring 119 so that the area overlapping with the light-emitting element 170 is as small as possible. The wiring 119 functions as a cathode auxiliary wiring. By electrically connecting the cathodes of each adjacent light-emitting element to the wiring 119, the potential variation of the cathodes can be reduced. Therefore, the display quality of the display device can be improved.

[0236] Furthermore, in Figure 9, the wiring 119 extends in the X direction and is electrically connected to adjacent electrodes 117 in the X direction, but the wiring 119 may also extend in the Y direction and be electrically connected to adjacent electrodes 117 in the Y direction. Alternatively, the wiring 119 may be arranged in a mesh pattern.

[0237] [Variation 2] As shown in Figure 10, an insulating layer 139 may be provided between the insulating layer 114 and the electrode 171. The insulating layer 139 functions as an etching stopper when etching a portion of the electrode 171, which functions as the anode, the EL layer 172, and the electrode 173, which functions as the cathode, in step A15.

[0238] The insulating layer 139 is made of a material that is difficult to etch in step A15. In particular, if step A15 is performed by a dry etching method, or is primarily performed by a dry etching method, it is preferable to provide the insulating layer 139. By providing the insulating layer 139, the degree of freedom in the process design of step A15 can be increased, and productivity and reliability can be improved.

[0239] [Second element substrate 152] Next, we will explain the method for manufacturing the second element substrate 152.

[0240] [Process B1] An insulating layer 122 is formed on the substrate 121 (see Figure 11A). The same material as that used for substrate 111 can be used for substrate 121.

[0241] [Process B2] Next, a light-shielding layer 132 is placed on top of the insulating layer 122 (see Figure 11B).

[0242] [Process B3] Next, a colored layer 131 is provided on top of the insulating layer 122 and the light-shielding layer 132.

[0243] The coloring layer 131 can be formed using a photosensitive material and processed into an island shape by photolithography or the like. The coloring layer 131 and the light-shielding layer 132 may be provided as necessary. Therefore, there may be a case where at least one of the coloring layer 131 and the light-shielding layer 132 is not provided. In the display device 100, the light-shielding layer 132 is provided so as to overlap with the peripheral circuit region 232, the peripheral circuit region 233, etc.

[0244] In this embodiment, a coloring layer 131R that transmits the red color gamut, a coloring layer 131G that transmits the green color gamut, and a coloring layer 131B that transmits the blue color gamut are provided. When the coloring layer 131 and the light-shielding layer 132 are provided, a region where the coloring layer 131 and the light-shielding layer 132 overlap with each other is formed in the peripheral portion of the coloring layer 131.

[0245] [Process B4] Next, an insulating layer 133 is formed on the coloring layer 131 and the light-shielding layer 132 (see FIG. 11C).

[0246] The insulating layer 133 preferably functions as a planarization layer. Resins such as acrylic resin and epoxy resin can be preferably used for the insulating layer 133. An inorganic insulating layer may be used as the insulating layer 133.

[0247] The second element substrate 152 can be fabricated as described above.

[0248] 〔Display device 100〕 Next, a method for fabricating the display device 100 using the first element substrate 151 and the second element substrate 152 will be described.

[0249] The first element substrate 151 and the second element substrate 152 are bonded together with an adhesive layer 142 interposed therebetween such that the coloring layer 131 and the light-emitting element 170 face each other (see FIG. 12). At this time, the light-emitting region of the light-emitting element 170 is bonded so as to overlap with the coloring layer 131.

[0250] As the adhesive layer 142, various types of curing adhesives can be used, such as UV-curing adhesives, reaction-curing adhesives, thermosetting adhesives, and anaerobic adhesives. Adhesive sheets may also be used.

[0251] The display device 100 can be manufactured in the manner described above.

[0252] [Variation] Figure 13 shows a cross-section of a modified display device 100A, which is a modified version of the display device 100. The display device 100A has a first element substrate 151 and a second element substrate 152A. The second element substrate 152A is a modified version of the second element substrate 152, differing in that it includes a touch sensor 370 between the substrate 121 and the colored layer 131. In this embodiment, the touch sensor 370 includes a conductive layer 374, an insulating layer 375, a conductive layer 376a, a conductive layer 376b, a conductive layer 377, and an insulating layer 378.

[0253] It is preferable that the conductive layers 376a, 376b, and 377 be formed from a light-transmitting conductive material. However, generally, light-transmitting conductive materials have a higher resistivity than non-light-transmitting conductive materials (light-shielding conductive materials). Therefore, in order to achieve larger size and higher resolution of the touch sensor, the conductive layers 376a, 376b, and 377 may be formed from a metal material with low resistivity.

[0254] Furthermore, when conductive layers 376a, 376b, and 377 are formed from metallic materials, it is preferable to reduce external light reflection. Generally, metallic materials have high reflectivity, but their reflectivity can be reduced and they can be made darker by applying oxidation treatment or the like.

[0255] Furthermore, conductive layers 376a, 376b, and 377 may be laminated with a metal layer and a layer with low reflectivity (also called a "dark layer"). Since the dark layer has high resistivity, it is preferable to laminate a metal layer and a dark layer. Examples of dark layers include layers containing copper oxide, copper chloride, or tellurium chloride. The dark layer may also be formed using metal nanoparticles such as Ag particles, Ag fibers, or Cu particles, nanocarbon particles such as carbon nanotubes (CNTs) or graphene, and conductive polymers such as PEDOT, polyaniline, or polypyrrole.

[0256] Furthermore, the touch sensor 370 may be a resistive or capacitive touch sensor, or an optical touch sensor using a photoelectric conversion element. Capacitive touch sensors include surface-type and projected-type capacitive touch sensors. Projected-type capacitive touch sensors include self-capacitive and mutual-capacitive types, mainly due to differences in the driving method. Mutual-capacitive touch sensors are preferred because they enable simultaneous multi-point detection.

[0257] The other components are the same as those of the display device 100, so a detailed explanation will be omitted.

[0258] Furthermore, the touch sensor may be provided on the outside of the substrate 121. For example, a sheet-shaped touch sensor may be placed on top of the display area 235.

[0259] The configuration shown in this embodiment can be used in appropriate combination with the configurations shown in other embodiments.

[0260] (Embodiment 2) In this embodiment, a more specific configuration example of the display device 100 will be described. Figure 15A is a block diagram illustrating the display device 100. As described in Embodiment 1, the display device 100 has a display area 235, a peripheral circuit area 232, and a peripheral circuit area 233.

[0261] The circuits included in peripheral circuit area 232 function, for example, as scan line driving circuits. The circuits included in peripheral circuit area 232 function, for example, as signal line driving circuits. Furthermore, some circuits may be provided at a position facing peripheral circuit area 232 across the display area 235. Similarly, some circuits may be provided at a position facing peripheral circuit area 233 across the display area 235. As mentioned above, the circuits included in peripheral circuit area 232 and peripheral circuit area 233 are sometimes collectively referred to as "peripheral driving circuits."

[0262] Various types of circuits can be used in the peripheral drive circuit, such as shift registers, level shifters, inverters, latches, analog switches, and logic circuits. Transistors and capacitive elements can also be used in the peripheral drive circuit. The transistors in the peripheral drive circuit can be formed using the same process as the transistors included in the pixel 230.

[0263] Furthermore, the display device 100 has m (where m is an integer of 1 or more) wires 236, each arranged substantially parallel to the others and whose potential is controlled by circuits included in the peripheral circuit region 232, and n (where n is an integer of 1 or more) wires 237, each arranged substantially parallel to the others and whose potential is controlled by circuits included in the peripheral circuit region 233.

[0264] The display area 235 has multiple pixels 230 arranged in a matrix. A pixel 230 controlling red light, a pixel 230 controlling green light, and a pixel 230 controlling blue light are combined into a single pixel 240, and full-color display can be achieved by controlling the amount of light emitted (luminescence) of each pixel 230. Therefore, these three pixels 230 each function as sub-pixels. That is, each of the three sub-pixels controls the amount of light emitted, such as red light, green light, or blue light (see Figure 15B1). Note that the color of light controlled by each of the three sub-pixels is not limited to a combination of red (R), green (G), and blue (B), but may also be cyan (C), magenta (M), and yellow (Y) (see Figure 15B2).

[0265] Also, four sub-pixels may be combined to function as one pixel. For example, a sub-pixel for controlling white light (W) may be added to three sub-pixels for controlling red light, green light, and blue light respectively (see Fig. 15B3). By adding a sub-pixel for controlling white light, the luminance of the display area can be increased. Also, a sub-pixel for controlling yellow light may be added to three sub-pixels for controlling red light, green light, and blue light respectively (see Fig. 15B4). Also, a sub-pixel for controlling white light may be added to three sub-pixels for controlling cyan light, magenta light, and yellow light respectively (see Fig. 15B5).

[0266] By increasing the number of sub-pixels that function as one pixel and appropriately combining sub-pixels for controlling lights such as red, green, blue, cyan, magenta, and yellow, the reproducibility of halftones can be improved. Therefore, the display quality can be enhanced.

[0267] Also, the display device according to one aspect of the present invention can reproduce color gamuts of various standards. For example, it can reproduce color gamuts such as the PAL (Phase Alternating Line) standard and the NTSC (National Television System Committee) standard used in television broadcasts, the sRGB (standard RGB) standard and the Adobe RGB standard widely used in display devices for electronic devices such as personal computers, digital cameras, and printers, the ITU-R BT.709 (International Telecommunication Union Radiocommunication Sector Broadcasting Service (Television) 709) standard used in HDTV (High Definition Television, also called high vision), the DCI-P3 (Digital Cinema Initiatives P3) standard used in digital cinema projection, and the ITU-R BT.2,020 (REC.2020 (Recommendation 2020)) standard used in UHDTV (Ultra High Definition Television, also called super high vision).

[0268] Furthermore, by arranging 240 pixels in a 1920 x 1080 matrix, a display device 100 capable of full-color display at a resolution known as Full HD (also called "2K resolution," "2K1K," or "2K"). Also, for example, by arranging 240 pixels in a 3840 x 2160 matrix, a display device 100 capable of full-color display at a resolution known as Ultra HD (also called "4K resolution," "4K2K," or "4K"). Furthermore, for example, by arranging 240 pixels in a 7680 x 4320 matrix, a display device 100 capable of full-color display at a resolution known as Super Hi-Vision (also called "8K resolution," "8K4K," or "8K"). By increasing the number of pixels, it is also possible to realize a display device 100 capable of full-color display at a resolution of 16K or 32K.

[0269] <Example of circuit configuration for 230 pixels> Figure 16 shows an example of the circuit configuration of a pixel 230. The pixel 230 has a pixel circuit 431 and a display element 432.

[0270] Each wire 236 is electrically connected to n pixel circuits 431 located in any row of the m rows and n columns of the display area 235. In addition, each wire 237 is electrically connected to m pixel circuits 431 located in any column of the m rows and n columns of the pixel circuits 431.

[0271] The pixel circuit 431 includes a transistor 436, a capacitive element 433, a transistor 251, and a transistor 434. The pixel circuit 431 is also electrically connected to a light-emitting element 170 that functions as a display element 432.

[0272] One of the source and drain electrodes of transistor 436 is electrically connected to a wiring to which a data signal (also called a "video signal") is supplied (hereinafter referred to as signal line DL_n). Furthermore, the gate electrode of transistor 436 is electrically connected to a wiring to which a gate signal is supplied (hereinafter referred to as scan line GL_m). Signal line DL_n and scan line GL_m correspond to wiring 237 and wiring 236, respectively.

[0273] Transistor 436 has the function of controlling the writing of data signals to node 435.

[0274] One of the pair of electrodes of the capacitive element 433 is electrically connected to node 435, and the other is electrically connected to node 437. Additionally, the source electrode and the other drain electrode of the transistor 436 are electrically connected to node 435.

[0275] The capacitive element 433 functions as a holding capacitor that holds the data written to node 435.

[0276] One of the source and drain electrodes of transistor 251 is electrically connected to the potential supply line VL_a, and the other is electrically connected to node 437. Furthermore, the gate electrode of transistor 251 is electrically connected to node 435.

[0277] One of the source and drain electrodes of transistor 434 is electrically connected to the potential supply line V0, and the other is electrically connected to node 437. Furthermore, the gate electrode of transistor 434 is electrically connected to the scan line GL_m.

[0278] One of the light-emitting element 170's anode or cathode is electrically connected to the potential supply line VL_b, and the other is electrically connected to node 437.

[0279] For example, an organic electroluminescent element (also called an organic EL element) can be used as the light-emitting element 170. However, the light-emitting element 170 is not limited to this, and for example, an inorganic EL element made of inorganic material may also be used.

[0280] Furthermore, the power supply potential can be, for example, the potential on the relatively higher or lower side. The power supply potential on the higher side is called the high power supply potential (also called "VDD"), and the power supply potential on the lower side is called the low power supply potential (also called "VSS"). In addition, the ground potential can be used as the high or low power supply potential. For example, if the high power supply potential is the ground potential, the low power supply potential is lower than the ground potential, and if the low power supply potential is the ground potential, the high power supply potential is higher than the ground potential.

[0281] For example, a high power supply potential VDD is supplied to one of the potential supply lines VL_a or VL_b, and a low power supply potential VSS is supplied to the other.

[0282] In a display device having pixel circuits 431, the circuits included in the peripheral circuit region 232 sequentially select the pixel circuits 431 of each row, and turn on transistors 436 and 434 to write a data signal to node 435.

[0283] When data is written to node 435, the pixel circuit 431 enters a holding state when transistors 436 and 434 are turned off. Furthermore, the amount of current flowing between the source and drain electrodes of transistor 251 is controlled according to the potential of the data written to node 435, and the light-emitting element 170 emits light with a brightness corresponding to the amount of current flowing. By performing this sequentially row by row, an image can be displayed.

[0284] The configuration shown in this embodiment can be used in appropriate combination with the configurations shown in other embodiments.

[0285] (Embodiment 3) This embodiment describes a light-emitting device that can be used in the light-emitting element 170.

[0286] Figure 17A shows a diagram representing a light-emitting device. The light-emitting device shown in Figure 17A has a first electrode 181, a second electrode 182, and an EL layer 183. The first electrode 181 corresponds to the electrode 171 shown in the above embodiment, the second electrode 182 corresponds to the electrode 173, and the EL layer 183 corresponds to the EL layer 172.

[0287] The EL layer 183 has a light-emitting layer 193, which contains a light-emitting material. Between the light-emitting layer 193 and the first electrode 181, a hole injection layer 191 and a hole transport layer 192 are provided.

[0288] Furthermore, the light-emitting layer 193 may contain a host material along with the light-emitting material. The host material is an organic compound with carrier transport properties. The host material may contain not just one type, but multiple types. In this case, it is preferable that the multiple organic compounds include an organic compound with electron transport properties and an organic compound with hole transport properties, as this allows for balancing the carriers within the light-emitting layer 193. Alternatively, the multiple organic compounds may all be organic compounds with electron transport properties, but their different electron transport properties can be used to adjust the electron transport properties in the light-emitting layer 193. By appropriately adjusting the carrier balance, a light-emitting device with a good lifetime can be provided. Furthermore, the configuration may include the formation of excitation complexes between the multiple organic compounds that constitute the host material, or between the host material and the light-emitting material. By forming excitation complexes with appropriate emission wavelengths, effective energy transfer to the light-emitting material can be achieved, providing a light-emitting device with high efficiency and a good lifetime.

[0289] In Figure 17A, the EL layer 183 is shown to include an emissive layer 193, a hole injection layer 191, and a hole transport layer 192, as well as electron transport layers 194 and 195. However, the configuration of the light-emitting device is not limited to these. None of these layers may be formed, or layers with other functions may be included.

[0290] Next, we will describe the detailed structure and material examples of the light-emitting device described above. The first electrode 181 is preferably formed using a metal, alloy, conductive compound, or mixture thereof with a large work function (specifically, 4.0 eV or more). Specifically, examples include indium tin oxide (ITO), indium tin oxide containing silicon or silicon oxide, indium zinc oxide, and indium oxide (IWZO) containing tungsten oxide and zinc oxide. These conductive metal oxide films are usually deposited by sputtering, but they may also be fabricated using methods such as the sol-gel method. Furthermore, by using the composite material described later in the layer in contact with the first electrode 181 in the EL layer 183, it becomes possible to select the electrode material regardless of the work function.

[0291] The EL layer 183 preferably has a multilayer structure, but there are no particular limitations on the multilayer structure, and various layer structures such as hole injection layer, hole transport layer, light-emitting layer, electron transport layer, electron injection layer, carrier block layer, exciton block layer, and charge generation layer can be applied. In this embodiment, two types of configurations will be described: one having a hole injection layer 191, a hole transport layer 192, a light-emitting layer 193, an electron transport layer 194, and an electron transport layer 195, as shown in Figure 17A, and another having a hole injection layer 191, a hole transport layer 192, a light-emitting layer 193, an electron transport layer 194, and a charge generation layer 196, as shown in Figure 17B. The materials constituting each layer are specifically described below.

[0292] The hole injection layer 191 is a layer containing an acceptor substance. Both organic and inorganic compounds can be used as the acceptor substance.

[0293] Examples of substances with acceptor properties include compounds having electron-withdrawing groups (halogen groups or cyano groups), such as 7,7,8,8-tetracyano-2,3,5,6-tetrafluoroquinodimethane (abbreviated as F4-TCNQ), chloranil, 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene (abbreviated as HAT-CN), 1,3,4,5,7,8-hexafluorotetracyano-naphthoquinodimethane (abbreviated as F6-TCNNQ), and 2-(7-dicyanomethylene-1,3,4,5,6,8,9,10-octafluoro-7H-pyrene-2-ylidene)malononitrile.

[0294] In addition to the organic compounds mentioned above, other acceptor materials that can be used include molybdenum oxide, vanadium oxide, ruthenium oxide, tungsten oxide, and manganese oxide. Furthermore, the hole injection layer 191 can also be formed by phthalocyanine-based complex compounds such as phthalocyanine (abbreviated as H2Pc) and copper phthalocyanine (abbreviated as CuPc), aromatic amine compounds, or polymers such as poly(3,4-ethylenedioxythiophene) / (polystyrene sulfonic acid) (abbreviated as PEDOT / PSS). Acceptor materials can extract electrons from adjacent hole transport layers (or hole transport materials) by applying an electric field.

[0295] Furthermore, a composite material containing the above-mentioned acceptor substance in a hole-transporting material can also be used as the hole injection layer 191. By using a composite material containing the acceptor substance in a hole-transporting material, it is possible to select the material for forming the electrode regardless of the work function. In other words, not only materials with a large work function but also materials with a small work function can be used as the first electrode 181.

[0296] Various organic compounds can be used as hole-transporting materials in composite materials, including aromatic amine compounds, carbazole derivatives, aromatic hydrocarbons, and polymer compounds (oligomers, dendrimers, polymers, etc.). -6 cm 2 It is preferable that the material has a hole mobility of / Vs or higher.

[0297] Furthermore, it is even more preferable that the hole-transporting material used in the composite material has a relatively deep HOMO level between -5.7 eV and -5.4 eV. Having a relatively deep HOMO level in the hole-transporting material used in the composite material facilitates the injection of holes into the hole transport layer 192 and makes it easier to obtain a light-emitting device with a good lifetime.

[0298] By forming the hole injection layer 191, the hole injection performance is improved, making it possible to obtain a light-emitting device with a low driving voltage. Furthermore, organic compounds with acceptor properties are easy to deposit and form films with, making them easy to use materials.

[0299] The hole transport layer 192 is formed by including a material having hole transport properties. The material having hole transport properties is 1 × 10 -6 cm 2 It is preferable to have a hole mobility of / Vs or higher. Examples of materials having the above hole transport properties include 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviated as NPB), N,N'-bis(3-methylphenyl)-N,N'-diphenyl-[1,1'-biphenyl]-4,4'-diamine (abbreviated as TPD), and 4,4'-bis[N-(spiro-9,9'-bifluoren-2-yl)-N-phenylamino]biphenyl (abbreviated as BSPB). In addition, the substances listed as materials having hole transport properties used in the composite material of the hole injection layer 191 can also be suitably used as materials constituting the hole transport layer 192.

[0300] The light-emitting layer 193 contains a light-emitting substance and a host material. The light-emitting layer 193 may also contain other materials. Furthermore, it may be a laminate of two layers with different compositions.

[0301] The luminescent material can be a fluorescent material, a phosphorescent material, a thermally activated delayed fluorescence (TADF) material, or any other luminescent material.

[0302] Examples of materials that can be used as fluorescent luminescent substances in the light-emitting layer 193 include 5,6-bis[4-(10-phenyl-9-antryl)phenyl]-2,2'-bipyridine (abbreviated as PAP2BPy), 5,6-bis[4'-(10-phenyl-9-antryl)biphenyl-4-yl]-2,2'-bipyridine (abbreviated as PAPP2BPy), and N,N'-diphenyl-N,N'-bis[4-(9-phenyl-9H-fluoren-9-yl)phenyl]pyrene-1,6-diamine (abbreviated as 1,6FLPAPrn). Other fluorescent luminescent substances can also be used.

[0303] When a phosphorescent material is used as the light-emitting substance in the light-emitting layer 193, possible materials include, for example, organometallic iridium complexes having a 4H-triazole skeleton, organometallic iridium complexes having a 1H-triazole skeleton, organometallic iridium complexes having an imidazole skeleton, and organometallic iridium complexes with a phenylpyridine derivative having an electron-withdrawing group as a ligand. These are compounds that exhibit blue phosphorescence and have emission wavelength peaks between 440 nm and 520 nm.

[0304] Other examples include organometallic iridium complexes with a pyrimidine skeleton, organometallic iridium complexes with a pyrazine skeleton, organometallic iridium complexes with a pyridine skeleton, and rare earth metal complexes such as tris(acetylacetonato)(monophenanthroline)terbium(III) (abbreviation: [Tb(acac)3(Phen)]). These are mainly compounds that exhibit green phosphorescence and have an emission wavelength peak between 500 nm and 600 nm. Organometallic iridium complexes with a pyrimidine skeleton are particularly preferred due to their outstanding reliability and luminescence efficiency.

[0305] Other examples include organometallic iridium complexes with a pyrimidine skeleton, organometallic iridium complexes with a pyrazine skeleton, organometallic iridium complexes with a pyridine skeleton, platinum complexes, and rare earth metal complexes. These compounds exhibit red phosphorescence and have an emission peak between 600 nm and 700 nm. Furthermore, organometallic iridium complexes with a pyrazine skeleton yield red emission with good chromaticity.

[0306] In addition to the phosphorescent compounds described above, other known phosphorescent substances may be selected and used.

[0307] As TADF materials, fullerenes and their derivatives, acridines and their derivatives, eosin derivatives, etc., can be used. Also, metal-containing porphyrins containing magnesium (Mg), zinc (Zn), cadmium (Cd), tin (Sn), platinum (Pt), indium (In), or palladium (Pd) can be used.

[0308] TADF materials are materials that have a small difference between the S1 and T1 energy levels and possess the ability to convert energy from triplet excitation energy to singlet excitation energy through reverse intersystem crossing. Therefore, triplet excitation energy can be upconverted to singlet excitation energy with only a small amount of thermal energy (reverse intersystem crossing), and singlet excited states can be efficiently generated. In addition, triplet excitation energy can be converted into luminescence.

[0309] Furthermore, excited complexes (also called exciplexes) that form excited states with two types of substances have an extremely small difference between the S1 and T1 levels and function as TADF materials that can convert triplet excitation energy into singlet excitation energy.

[0310] Furthermore, the phosphorescence spectrum observed at low temperatures (e.g., 77K to 10K) can be used as an indicator of the T1 level. For TADF materials, when a tangent is drawn at the short-wavelength tail of the fluorescence spectrum and the energy at the wavelength of the extrapolation is taken as the S1 level, and when a tangent is drawn at the short-wavelength tail of the phosphorescence spectrum and the energy at the wavelength of the extrapolation is taken as the T1 level, it is preferable that the difference between S1 and T1 is 0.3 eV or less, and more preferably 0.2 eV or less.

[0311] Furthermore, when using TADF material as a light-emitting material, it is preferable that the S1 level of the host material is higher than the S1 level of the TADF material. Also, it is preferable that the T1 level of the host material is higher than the T1 level of the TADF material.

[0312] Various carrier transport materials can be used as the host material for the light-emitting layer, such as electron transport materials, hole transport materials, and the TADF material mentioned above.

[0313] As materials having hole-transporting properties, organic compounds having an amine skeleton or a π-electron-rich heteroaromatic ring skeleton are preferred. Examples include compounds having an aromatic amine skeleton, a carbazole skeleton, a thiophene skeleton, and a furan skeleton. Among the above, compounds having an aromatic amine skeleton and compounds having a carbazole skeleton are preferred because they have good reliability, high hole transport properties, and contribute to reducing the driving voltage.

[0314] Preferred materials with electron transport properties include, for example, metal complexes or organic compounds having a π-electron-deficient heteroaromatic ring skeleton. Examples of organic compounds having a π-electron-deficient heteroaromatic ring skeleton include heterocyclic compounds having a polyazole skeleton, heterocyclic compounds having a diazine skeleton, heterocyclic compounds having a triazine skeleton, and heterocyclic compounds having a pyridine skeleton. Among the above, heterocyclic compounds having a diazine skeleton, heterocyclic compounds having a triazine skeleton, and heterocyclic compounds having a pyridine skeleton are preferred due to their good reliability. In particular, heterocyclic compounds having a diazine (pyrimidine or pyrazine) skeleton have high electron transport properties and contribute to reducing the driving voltage.

[0315] The TADF materials listed above can be used as host materials. When a TADF material is used as a host material, the triplet excitation energy generated by the TADF material is converted into singlet excitation energy through reverse intersystem crossing, and this energy is then transferred to the light-emitting material, thereby increasing the luminescence efficiency of the light-emitting device.

[0316] When using a fluorescent material as the light-emitting material, a material having an anthracene skeleton is preferred as the host material. Using a material having an anthracene skeleton as the host material for a fluorescent material makes it possible to realize a light-emitting layer with good luminescence efficiency and durability.

[0317] The electron transport layer 194 is a layer containing an electron-transporting material. As the electron-transporting material, any of the electron-transporting materials listed above as usable in the host material can be used.

[0318] Furthermore, the electron transport layer 194 has an electron mobility of 1 × 10⁻¹⁴ when the square root of the electric field strength [V / cm] is 600. -7 cm 2 / Vs or more 5×10 -5 cm 2It is preferable that the value is less than or equal to / Vs. By reducing the electron transport properties in the electron transport layer 194, the amount of electrons injected into the light-emitting layer can be controlled, preventing the light-emitting layer from becoming electron-excessive. Furthermore, it is preferable that the electron transport layer contains an electron-transporting material and an alkali metal or an alkali metal element, compound, or complex. These configurations are particularly preferable because they result in a good lifetime when the hole injection layer is formed as a composite material and the HOMO level of the hole-transporting material in the composite material is a relatively deep HOMO level between -5.7eV and -5.4eV. In this case, it is preferable that the HOMO level of the electron-transporting material is -6.0eV or higher.

[0319] Between the electron transport layer 194 and the second electrode 182, an electron transport layer 195 may be provided, which contains an alkali metal or alkaline earth metal or a compound thereof, such as lithium fluoride (LiF), cesium fluoride (CsF), calcium fluoride (CaF2), or 8-hydroxyquinolinatolithium (abbreviated as Liq). The electron transport layer 195 may be a layer made of an electron-transporting material containing an alkali metal or alkaline earth metal or a compound thereof, or an electride may be used. Examples of electrides include a material obtained by adding electrons to a mixed oxide of calcium and aluminum at a high concentration.

[0320] Furthermore, as the electron transport layer 195, it is also possible to use a layer containing an alkali metal or alkaline earth metal fluoride in a concentration (50 wt% or more) that is in a microcrystalline state, in a material having electron transport properties (preferably an organic compound having a bipyridine skeleton). Since this layer has a low refractive index, it is possible to provide a light-emitting device with better external quantum efficiency.

[0321] Alternatively, a charge generation layer 196 may be provided instead of the electron transport layer 195 (Figure 17B). The charge generation layer 196 is a layer that can inject holes into the layer in contact with the cathode side and electrons into the layer in contact with the anode side by applying a potential. The charge generation layer 196 includes at least a P-type layer 197. The P-type layer 197 is preferably formed using a composite material listed above as a material capable of constituting the hole injection layer 191. The P-type layer 197 may also be constructed by laminating a film containing the acceptor material and a film containing the hole transport material as materials constituting the composite material. By applying a potential to the P-type layer 197, electrons are injected into the electron transport layer 194 and holes into the second electrode 182, which is the cathode, and the light-emitting device operates. Furthermore, since the organic compound in one aspect of the present invention is an organic compound with a low refractive index, by using it in the P-type layer 197, a light-emitting device with good external quantum efficiency can be obtained.

[0322] Furthermore, it is preferable that the charge generation layer 196 includes, in addition to the P-type layer 197, one or both of the electron relay layer 198 and the electron injection buffer layer 199.

[0323] The electron relay layer 198 contains at least an electron-transporting material and has the function of preventing interaction between the electron injection buffer layer 199 and the P-type layer 197, thereby smoothly transferring electrons. Preferably, the LUMO level of the electron-transporting material contained in the electron relay layer 198 is between the LUMO level of the acceptor material in the P-type layer 197 and the LUMO level of the material contained in the layer in contact with the charge generation layer 196 in the electron transport layer 194. The specific energy level of the LUMO level of the electron-transporting material used in the electron relay layer 198 is preferably -5.0 eV or higher, more preferably -5.0 eV or higher and -3.0 eV or lower. Preferably, the electron-transporting material used in the electron relay layer 198 is a phthalocyanine-based material or a metal complex having a metal-oxygen bond and an aromatic ligand.

[0324] The electron injection buffer layer 199 can use materials with high electron injection potential, such as alkali metals, alkaline earth metals, rare earth metals, and compounds thereof (alkali metal compounds (including oxides such as lithium oxide, halides, and carbonates such as lithium carbonate and cesium carbonate), alkaline earth metal compounds (including oxides, halides, and carbonates), or rare earth metal compounds (including oxides, halides, and carbonates)).

[0325] Furthermore, if the electron injection buffer layer 199 is formed by including an electron-transporting substance and a donor substance, the donor substance can include alkali metals, alkaline earth metals, rare earth metals, and compounds thereof (alkali metal compounds (including oxides such as lithium oxide, halides, and carbonates such as lithium carbonate and cesium carbonate), alkaline earth metal compounds (including oxides, halides, and carbonates), or rare earth metal compounds (including oxides, halides, and carbonates)), as well as organic compounds such as tetratianaphthalene (abbreviated as TTN), nickerosene, and decamethylnickerosene. The electron-transporting substance can be formed using the same materials as those used to constitute the electron transport layer 194 described earlier.

[0326] As the material forming the second electrode 182, metals, alloys, electrically conductive compounds, and mixtures thereof with a small work function (specifically, 3.8 eV or less) can be used. Specific examples of such cathode materials include alkali metals such as lithium (Li) or cesium (Cs), elements belonging to Group 1 or 2 of the periodic table such as magnesium (Mg), calcium (Ca), and strontium (Sr), and alloys containing these elements (MgAg, AlLi), rare earth metals such as europium (Eu) and ytterbium (Yb), and alloys containing these elements. However, by providing an electron injection layer between the second electrode 182 and the electron transport layer, various conductive materials such as Al, Ag, ITO, silicon, or indium oxide-tin oxide containing silicon oxide can be used as the second electrode 182, regardless of the magnitude of their work functions. These conductive materials can be deposited using dry methods such as vacuum deposition or sputtering, inkjet methods, or spin coating methods. Alternatively, the material may be formed using a wet process with a sol-gel method, or it may be formed using a wet process with a paste of a metallic material.

[0327] Furthermore, various methods can be used to form the EL layer 183, regardless of whether they are dry or wet methods. For example, vacuum deposition, gravure printing, offset printing, screen printing, inkjet printing, or spin coating may be used.

[0328] Furthermore, each electrode or layer described above may be formed using different film deposition methods.

[0329] The configuration of the layer provided between the first electrode 181 and the second electrode 182 is not limited to those described above. However, a configuration is preferred in which a light-emitting region is provided at a location away from the first electrode 181 and the second electrode 182 where holes and electrons recombine, in order to suppress quenching caused by the proximity of the light-emitting region to the electrode or the metal used in the carrier injection layer.

[0330] Furthermore, the hole transport layer and electron transport layer in contact with the light-emitting layer 193, and especially the carrier transport layer near the recombination region in the light-emitting layer 193, are preferably composed of a material whose band gap is larger than that of the light-emitting material constituting the light-emitting layer or the light-emitting material contained in the light-emitting layer, in order to suppress energy transfer from excitons generated in the light-emitting layer.

[0331] Next, an embodiment of a light-emitting device (also called a stacked element or tandem element) with a configuration in which multiple light-emitting units are stacked will be described with reference to Figure 17C. This light-emitting device has multiple light-emitting units between the anode and the cathode. Each light-emitting unit has a configuration almost identical to the EL layer 183 shown in Figure 17A. In other words, the light-emitting device shown in Figure 17C is a light-emitting device with multiple light-emitting units, while the light-emitting device shown in Figure 17A or Figure 17B is a light-emitting device with one light-emitting unit.

[0332] In Figure 17C, a first light-emitting unit 511 and a second light-emitting unit 512 are stacked between the anode 501 and the cathode 502, and a charge generation layer 513 is provided between the first light-emitting unit 511 and the second light-emitting unit 512. The anode 501 and the cathode 502 correspond to the first electrode 181 and the second electrode 182 in Figure 17A, respectively, and the same components described in the explanation of Figure 17A can be applied. Furthermore, the first light-emitting unit 511 and the second light-emitting unit 512 may have the same configuration or different configurations.

[0333] The charge generation layer 513 has the function of injecting electrons into one light-emitting unit and holes into the other light-emitting unit when a voltage is applied to the anode 501 and cathode 502. That is, in Figure 17C, when a voltage is applied such that the potential of the anode is higher than the potential of the cathode, the charge generation layer 513 only needs to inject electrons into the first light-emitting unit 511 and holes into the second light-emitting unit 512.

[0334] The charge generation layer 513 is preferably formed with the same configuration as the charge generation layer 196 described in Figure 17B. The composite material of organic compound and metal oxide has excellent carrier implantation and carrier transport properties, enabling low-voltage and low-current operation. If the anode side of the light-emitting unit is in contact with the charge generation layer 513, the charge generation layer 513 can also act as a hole injection layer for the light-emitting unit, so the light-emitting unit does not need to have a hole injection layer.

[0335] Furthermore, when an electron injection buffer layer 199 is provided in the charge generation layer 513, the electron injection buffer layer 199 plays the role of an electron injection layer in the anode-side light-emitting unit, so it is not necessarily required to form an electron injection layer in the anode-side light-emitting unit.

[0336] Figure 17C illustrates a light-emitting device having two light-emitting units, but the same principles apply to light-emitting devices with three or more stacked light-emitting units. As in the light-emitting device according to this embodiment, by arranging multiple light-emitting units separated between a pair of electrodes by a charge generation layer 513, high-brightness light emission can be achieved while maintaining a low current density, and a longer-life element can be realized. Furthermore, a light-emitting device that can be driven at a low voltage and consumes little power can be realized.

[0337] Furthermore, by making the light-emitting colors of each light-emitting unit different, it is possible to obtain a desired color of light emission from the entire light-emitting device. For example, in a light-emitting device having two light-emitting units, it is possible to obtain a light-emitting device that emits white light as a whole by obtaining red and green light-emitting colors from the first light-emitting unit and blue light-emitting color from the second light-emitting unit.

[0338] Furthermore, each of the layers, such as the EL layer 183, the first light-emitting unit 511, the second light-emitting unit 512, and the charge generation layer, as well as the electrodes, can be formed using methods such as vapor deposition (including vacuum deposition), droplet ejection (also known as inkjet printing), coating, and gravure printing. They may also contain low-molecular-weight materials, medium-molecular-weight materials (including oligomers and dendrimers), or polymer materials.

[0339] The configuration shown in this embodiment can be used in appropriate combination with the configurations shown in other embodiments.

[0340] (Embodiment 4) This embodiment describes electronic equipment to which a display device according to one aspect of the present invention can be applied.

[0341] A display device according to one aspect of the present invention can be applied to the display unit of an electronic device. Therefore, it is possible to realize an electronic device with high display quality, or an extremely high-definition electronic device, or a highly reliable electronic device.

[0342] Electronic devices using a display device according to one aspect of the present invention include televisions, monitors and other display devices, lighting devices, desktop or notebook personal computers, word processors, and DVDs (Digital Versatile). Examples include image playback devices that play still images or videos stored on recording media such as discs, portable CD players, radios, tape recorders, headphone stereos, stereos, desk clocks, wall clocks, cordless telephone handsets, transceivers, car phones, mobile phones, personal digital assistants, tablet devices, portable game consoles, fixed game machines such as pachinko machines, calculators, electronic organizers, e-book readers, electronic translators, voice input devices, video cameras, digital still cameras, electric shavers, high-frequency heating devices such as microwave ovens, electric rice cookers, electric washing machines, electric vacuum cleaners, water heaters, electric fans, hair dryers, air conditioning equipment such as air conditioners, humidifiers, and dehumidifiers, dishwashers, dish dryers, clothes dryers, futon dryers, electric refrigerators, electric freezers, electric refrigerator-freezers, DNA storage freezers, flashlights, tools such as chainsaws, smoke detectors, and medical equipment such as dialysis machines. Furthermore, industrial equipment such as guide lights, traffic lights, conveyor belts, elevators, escalators, industrial robots, power storage systems, and energy storage devices for power leveling and smart grids can also be included in the category of electronic equipment. In addition, mobile devices propelled by engines using fuel or electric motors using electricity from energy storage devices may also be included in the category of electronic equipment. Examples of such mobile devices include electric vehicles (EVs), hybrid vehicles (HVs) that combine internal combustion engines and electric motors, plug-in hybrid vehicles (PHVs), tracked vehicles in which the tires and wheels of these vehicles are replaced with tracks, motorized bicycles including electric assist bicycles, motorcycles, electric wheelchairs, golf carts, small or large vessels, submarines, helicopters, aircraft, rockets, artificial satellites, space probes, planetary probes, and spacecraft.

[0343] An electronic device according to one aspect of the present invention can be incorporated along the curved surface of the interior or exterior walls of a house or building, or the interior or exterior of an automobile.

[0344] An electronic device according to one aspect of the present invention may have a secondary battery, and it is preferable that the secondary battery can be charged using contactless power transmission.

[0345] Examples of secondary batteries include lithium-ion batteries, nickel-metal hydride batteries, nickel-cadmium batteries, organic radical batteries, lead-acid batteries, air batteries, nickel-zinc batteries, and silver-zinc batteries.

[0346] An electronic device according to one aspect of the present invention may have an antenna. By receiving signals with the antenna, the display unit can display images and information. Furthermore, if the electronic device has an antenna and a secondary battery, the antenna may be used for contactless power transmission.

[0347] An electronic device according to one aspect of the present invention may have sensors (including those with functions to measure force, displacement, position, velocity, acceleration, angular velocity, rotational speed, distance, light, liquid, magnetism, temperature, chemical substances, sound, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, gradient, vibration, odor, or infrared radiation).

[0348] An electronic device according to one aspect of the present invention can have various functions. For example, it can have a function to display various information (still images, videos, text images, etc.) on a display unit, a touch panel function, a function to display a calendar, date or time, a function to execute various software (programs), a wireless communication function, a function to read programs or data recorded on a recording medium, and so on.

[0349] Furthermore, electronic devices having multiple display units may have functions such as primarily displaying image information on one display unit and primarily displaying text information on another display unit, or displaying three-dimensional images by displaying images that take parallax into account on multiple display units. Furthermore, electronic devices having an image receiving unit may have functions such as capturing still images or moving images, automatically or manually correcting captured images, saving captured images to a recording medium (external or built into the electronic device), and displaying captured images on a display unit. It should be noted that the functions of an electronic device according to one aspect of the present invention are not limited to these, and it may have a variety of functions.

[0350] A display device according to one aspect of the present invention can display extremely high-resolution images. Therefore, it can be suitably used in portable electronic devices, wearable electronic devices, and e-book terminals. It can also be suitably used in VR (Virtual Reality) devices, AR (Augmented Reality) devices, and the like.

[0351] Figure 18A shows the external appearance of the head-mounted display 810. The head-mounted display 810 includes a mounting part 811, lenses 812, a main body 813, a display unit 814, a cable 815, etc. A battery 816 is also built into the mounting part 811. A display device according to one embodiment of the present invention can be applied to the display unit 814.

[0352] Cable 815 supplies power from battery 816 to main unit 813. Main unit 813 is equipped with a wireless receiver and can display received image data and other video information on display unit 814. In addition, a camera provided on main unit 813 captures the movement of the user's eyeballs and / or eyelids, and by calculating the user's gaze based on that information, the user's gaze can be used as an input means.

[0353] Furthermore, the attachment portion 811 may be provided with multiple electrodes in positions that come into contact with the user. The main body 813 may have a function to recognize the user's gaze by detecting the current flowing through the electrodes in accordance with the user's eye movements. It may also have a function to monitor the user's pulse by detecting the current flowing through the electrodes. The attachment portion 811 may also have various sensors such as a temperature sensor, a pressure sensor, and an acceleration sensor, and may have a function to display the user's biometric information on the display unit 814. It may also detect the user's head movements and change the image displayed on the display unit 814 in accordance with those movements.

[0354] Figure 18B shows the external appearance of the head-mounted display 820. The head-mounted display 820 is a goggle-type information processing device.

[0355] The head-mounted display 820 comprises a housing 821, two display units 822, operation buttons 823, and a band-shaped fixing device 824. Having two display units 822 allows the user to view one display unit per eye. This enables the display of high-resolution images, even when performing 3D displays using parallax. Furthermore, the display units 822 are curved in an arc shape with the user's eye as the approximate center. This ensures a constant distance from the user's eye to the display surface of the display unit, allowing the user to see more natural images. Additionally, even if the brightness and / or chromaticity of the light from the display unit changes depending on the viewing angle, the user's eye is positioned in the direction of the normal to the display surface of the display unit, effectively negating this effect and enabling the display of more realistic images.

[0356] The operation button 823 has functions such as a power button. The device may also have other buttons besides the operation button 823.

[0357] A display device according to one aspect of the present invention can be applied to the display unit 822. Because the display device according to one aspect of the present invention has extremely high resolution, pixels are difficult for the user to see, and a more realistic image can be displayed.

[0358] Figure 18C shows the external appearance of the camera 830 with the viewfinder 840 attached.

[0359] The camera 830 includes a housing 831, a display unit 832, operation buttons 833, a shutter button 834, and the like. The camera 830 also has a detachable lens 836 attached to it.

[0360] Here, the camera 830 is configured so that the lens 836 can be removed from the housing 831 and replaced, but the lens 836 and the housing could also be integrated.

[0361] The camera 830 can take an image by pressing the shutter button 834. Additionally, the display unit 832 functions as a touch panel, and images can also be taken by touching the display unit 832.

[0362] The camera body 831 of the camera 830 has a mount with electrodes, and in addition to the viewfinder 840, a strobe device and the like can be connected to it.

[0363] The viewfinder 840 includes a housing 841, a display unit 842, buttons 843, etc.

[0364] The housing 841 has a mount that engages with the mount of the camera 830, allowing the viewfinder 840 to be attached to the camera 830. The mount also has electrodes, which allow images and other data received from the camera 830 to be displayed on the display unit 842.

[0365] Button 843 functions as a power button. Button 843 can be used to switch the display on and off of the display unit 842.

[0366] A display device according to one aspect of the present invention can be applied to the display unit 832 of the camera 830 and the display unit 842 of the viewfinder 840.

[0367] In Figure 18C, the camera 830 and the viewfinder 840 are shown as separate electronic devices and are configured to be detachable. However, the camera 830's housing 831 may also have a viewfinder equipped with a display device according to one aspect of the present invention built into it.

[0368] The information terminal 850 shown in Figure 18D includes a housing 851, a display unit 852, a microphone 857, a speaker unit 854, a camera 853, and an operation switch 855. A display device according to one embodiment of the present invention can be applied to the display unit 852. The display unit 852 also functions as a touch panel. Furthermore, the information terminal 850 is equipped with an antenna, battery, etc. inside the housing 851. The information terminal 850 can be used, for example, as a smartphone, mobile phone, tablet information terminal, tablet personal computer, e-book reader, etc.

[0369] Figure 18E shows an example of a wristwatch-type information terminal. The information terminal 860 includes a housing 861, a display unit 862, a band 863, a buckle 864, an operation switch 865, input / output terminals 866, etc. The information terminal 860 also has an antenna and battery inside the housing 861. The information terminal 860 can run various applications such as mobile phone calls, email, document viewing and creation, music playback, internet communication, and computer games.

[0370] Furthermore, the display unit 862 is equipped with a touch sensor and can be operated by touching the screen with a finger or stylus. For example, an application can be launched by touching the icon 867 displayed on the display unit 862. The operation switch 865 can have various functions, including setting the time, turning the power on and off, turning wireless communication on and off, activating and deactivating silent mode, and activating and deactivating power saving mode. For example, the functions of the operation switch 865 can also be configured by the operating system built into the information terminal 860.

[0371] Furthermore, the information terminal 860 is capable of performing standardized short-range wireless communication. For example, it can communicate with a wireless communication-enabled headset to make hands-free calls. The information terminal 860 is also equipped with an input / output terminal 866, which can be used to send and receive data with other information terminals. It can also be charged via the input / output terminal 866. Note that charging may be performed by wireless power supply without using the input / output terminal 866.

[0372] Figure 18F is a perspective view showing a television device 870. The television device 870 includes a housing 871, a display unit 872, a speaker 873, operation keys 874 (including a power switch or operation switches), connection terminals 875, a sensor 876 (including functions for measuring distance, light, temperature, etc.), and the like. A display device according to one embodiment of the present invention can be applied to the display unit 872. The television device 870 can incorporate a display device of, for example, 50 inches or larger, or 100 inches or larger, into the display unit 872.

[0373] The configuration shown in this embodiment can be used in appropriate combination with the configurations shown in other embodiments. [Explanation of symbols]

[0374] 100: Display device, 111: Substrate, 112: Insulating layer, 113: Insulating layer, 114: Insulating layer, 115: Insulating layer, 116: Insulating layer, 117: Electrode, 118: Conductive layer, 119: Wiring, 121: Substrate, 122: Insulating layer, 124: FPC, 125: Wiring, 131: Coloring layer, 132: Light-shielding layer, 133: Insulating layer, 138: Connection layer, 139: Insulating layer, 142: Adhesive layer, 151: Element substrate, 152: Element substrate

Claims

[Claim 1] A process of forming an anode on an insulating layer, The process of forming an EL layer on the anode, The step of forming a cathode on the EL layer, A step of selectively removing a portion of the anode, the EL layer, and the cathode to form a plurality of light-emitting elements, The process includes forming a conductive layer that covers the plurality of light-emitting elements, Each of the plurality of light-emitting elements is electrically connected to the conductive layer, A method for manufacturing a display device having a light-transmitting conductive layer.

Images