Method for manufacturing a display device

Abstract

The present invention provides a method for producing a novel display device. The method for producing the display device includes: a step for forming an anode, a first EL layer, a first cathode, and a first layer in this order; a step for forming a first resist mask on the first layer; a step for selectively removing a portion from each of the anode, the first EL layer, the first cathode, and the first layer; a step for removing a portion of the first resist mask; a step for selectively removing another portion from each of the first EL layer, the first cathode, and the first layer; and a step for removing the first resist mask. The first resist mask is a multi-gradation mask.

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 (also called "light-emitting devices") 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] In addition, when forming an organic EL layer such as a light-emitting layer with a low-molecular material, a method using a metal mask for vacuum evaporation 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] Partition walls provided between pixels (also referred to as "dikes" or "banks") have effects such as improving the display quality of a display device and reducing power consumption. On the other hand, in order to obtain sufficient effects, a certain amount of partition walls is required, so it is difficult to reduce the occupied area of the partition walls, and it has been difficult to improve the pixel aperture ratio, achieve high definition, and miniaturize.

[0008] In addition, since a metal mask has inferior dimensional accuracy compared to a resist mask and is likely to be deformed by the influence of heat generated at the evaporation source, it has been difficult to improve the pixel aperture ratio and achieve high definition in forming a light-emitting layer for each pixel using a metal mask.

[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 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. Or, one aspect of the present invention aims to provide a method for manufacturing a novel display device or a method for manufacturing a novel 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] One aspect of the present invention is a method for manufacturing a display device including first to third light-emitting elements, comprising: a first manufacturing step of forming a first light-emitting element; a second manufacturing step of forming a second light-emitting element; and a third manufacturing step of forming a third light-emitting element, wherein the first manufacturing step comprises: sequentially forming an anode, a first EL layer, a first cathode, and a first layer; forming a first resist mask on the first layer; selectively removing a portion of each of the anode, the first EL layer, the first cathode, and the first layer; removing a portion of the first resist mask; selectively removing other portions of each of the first EL layer, the first cathode, and the first layer; and removing the first resist mask, wherein the second manufacturing step comprises: sequentially forming a second EL layer, a second cathode, and a second layer; and forming a second resist on the second layer The first manufacturing step comprises the steps of forming a mask, selectively removing a portion of the anode, second EL layer, second cathode, and second layer, removing a portion of the second resist mask, selectively removing other portions of the second EL layer, second cathode, and second layer, and removing the second resist mask. The third manufacturing step comprises the steps of sequentially forming the third EL layer, third cathode, and third layer, forming a third resist mask on the third layer, selectively removing a portion of the anode, third EL layer, third cathode, and third layer, removing a portion of the third resist mask, selectively removing other portions of the third EL layer, third cathode, and third layer, and removing the third resist mask.

[0012] It is preferable that each of the first to third resist masks is formed using a multi-gradation mask. For example, in the second fabrication step, the second EL layer, the second cathode, and the second layer are formed covering the first light-emitting element. For example, in the third fabrication step, the third EL layer, the third cathode, and the third layer are formed covering the first and second light-emitting elements.

[0013] Preferably, each of the first to third EL layers contains an organic EL material. Preferably, the first to third light-emitting elements are covered with a fourth layer. The fourth layer may be, for example, aluminum oxide formed by the ALD method. Preferably, a first conductive layer is provided which is electrically connected to each of the first to third cathodes. [Effects of the Invention]

[0014] 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 display device or semiconductor device with low power consumption, or a highly productive display device or semiconductor device, or a novel display device or semiconductor device, or a novel method for manufacturing a display device or a novel method for manufacturing a semiconductor device.

[0015] 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]

[0016] Figures 1A to 1C illustrate examples of the configuration of a display device. Figure 2 illustrates an example of a display device configuration. Figure 3 illustrates an example of a display device configuration. Figure 4 illustrates an example of a display device configuration. Figure 5 illustrates an example of a display device configuration. Figure 6 illustrates an example of a display device configuration. Figure 7 illustrates an example of a display device configuration. Figure 8 illustrates an example of a display device configuration. Figure 9 illustrates an example of a display device configuration. Figure 10 illustrates an example of a display device configuration. Figures 11A to 11C illustrate an example of a method for manufacturing a display device. Figures 12A to 12C illustrate an example of a method for manufacturing a display device. Figures 13A and 13B illustrate examples of methods for manufacturing a display device. Figures 14A and 14B illustrate an example of a method for manufacturing a display device. Figures 15A and 15B illustrate an example of a method for manufacturing a display device. Figures 16A and 16B illustrate an example of a method for manufacturing a display device. Figures 17A and 17B illustrate an example of a method for manufacturing a display device. Figures 18A and 18B illustrate examples of methods for manufacturing a display device. Figures 19A and 19B illustrate an example of a method for manufacturing a display device. Figures 20A and 20B illustrate examples of methods for manufacturing a display device. Figures 21A and 21B illustrate an example of a method for manufacturing a display device. Figures 22A and 22B illustrate examples of methods for manufacturing a display device. Figure 23A is a diagram illustrating the classification of crystal structures. Figure 23B is a diagram illustrating the XRD spectrum of the CAAC-IGZO film. Figure 23C is a diagram illustrating the micro-electron diffraction pattern of the CAAC-IGZO film. Figures 24A1, 24A2, 24B1, and 24B2 illustrate multi-level masks. Figures 25A and 25B1 to 25B7 illustrate examples of display device configurations. Figures 26A to 26D illustrate examples of pixel circuit configurations. Figures 27A to 27D illustrate examples of the configuration of a light-emitting element. Figures 28A to 28C illustrate examples of transistor configurations. Figures 29A to 29C illustrate examples of transistor configurations. Figures 30A to 30C illustrate examples of transistor configurations. Figures 31A and 31B show examples of electronic devices. Figures 32A to 32D show examples of electronic devices. Figures 33A to 33F show examples of electronic devices. [Modes for carrying out the invention]

[0017] 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.

[0018] 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.).

[0019] 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).

[0020] 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.

[0021] 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).

[0022] 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 scope 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.).

[0023] 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.

[0024] 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.

[0025] 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.

[0026] Furthermore, in this specification, "capacitive element" can refer 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." In addition, the term "a pair of electrodes" in "capacitance" can be replaced with terms such as "a pair of conductors," "a pair of conductive regions," and "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.

[0027] 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.

[0028] 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".

[0029] 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.

[0030] 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.

[0031] "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."

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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."

[0036] 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.

[0037] 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." 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." Similarly, the reverse is also true; terms such as "signal line" may be changed to the term "power line." In addition, the term "potential" applied to the wiring may be changed to the term "signal," depending on the circumstances or situation. Similarly, the reverse is also true; terms such as "signal" may be changed to the term "potential."

[0038] 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.

[0039] 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.

[0040] 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.

[0041] One example of a mechanical switch is a switch that uses 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.

[0042] 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.

[0043] 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 of a transistor, the metal oxide may be referred to as an oxide semiconductor. In other words, when a metal oxide is used in the channel formation region of a transistor having at least one of amplification, rectification, and switching functions, the metal oxide can be referred to as a metal oxide semiconductor. Furthermore, when "OS transistor" is mentioned, it can be replaced with a transistor having a metal oxide or oxide semiconductor.

[0044] Furthermore, in this specification, metal oxides containing nitrogen may also be collectively referred to as metal oxides. Alternatively, metal oxides containing nitrogen may be called metal oxynitrides.

[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, the description of some components may be omitted in perspective views or top views, etc. Also, in order to make the drawings easier to understand, notations such as hatching may be omitted.

[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 code is used for multiple elements, and especially when it is necessary to distinguish them, an identifying character such as "A", "a", "_1", "[i]", or "[m,n]" may be appended to the end of the code. For example, multiple pixels 230 may be referred to as pixel 230R, pixel 230G, or pixel 230B. In other words, when describing something common to pixels 230R, 230G, and 230B, or when it is not necessary to distinguish between them, they may simply be referred to as "pixel 230".

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

[0050] In this specification, a structure in which different light-emitting layers are created or painted for each color of light-emitting device (e.g., blue (B), green (G), and red (R)) may be referred to as an SBS (Side By Side) structure. Also, in this specification, a light-emitting device capable of emitting white light may be referred to as a white light-emitting device. A white light-emitting device can be combined with a colored layer (e.g., a color filter) to realize a full-color display device.

[0051] Furthermore, light-emitting devices can be broadly classified into single-structure and tandem-structure devices. A single-structure device has one light-emitting unit between a pair of electrodes, and it is preferable that this light-emitting unit includes one or more light-emitting layers. To obtain white light emission, one should select light-emitting layers such that the light emitted from each of the two or more layers is complementary in color. For example, by making the light-emitting color of the first light-emitting layer and the light-emitting color of the second light-emitting layer complementary, a configuration that emits white light as a whole can be obtained. The same applies to light-emitting devices having three or more light-emitting layers.

[0052] A tandem device preferably has two or more light-emitting units between a pair of electrodes, and each light-emitting unit preferably includes one or more light-emitting layers. To obtain white light emission, the device should be configured such that the light from the light-emitting layers of the multiple light-emitting units is combined to produce white light emission. The configuration for obtaining white light emission is the same as that for a single-structure device. In a tandem device, it is preferable to provide an intermediate layer, such as a charge-generating layer, between the multiple light-emitting units.

[0053] Furthermore, when comparing the aforementioned white light-emitting devices (single or tandem structure) with SBS structure light-emitting devices, SBS structure light-emitting devices can consume less power than white light-emitting devices. If you want to keep power consumption low, it is preferable to use SBS structure light-emitting devices. On the other hand, white light-emitting devices are preferable because their manufacturing process is simpler than that of SBS structure light-emitting devices, which can lead to lower manufacturing costs or higher manufacturing yields.

[0054] (Embodiment 1) A display device 100 according to one aspect of the present invention will be described with reference to the drawings.

[0055] <<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, a cathode contact area 234, etc. Figure 1A 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 a display device 100 and an FPC 124.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] 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. Pixel 240 includes pixels 230R, 230G, and 230B. As mentioned above, in this specification and elsewhere, when describing matters 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."

[0060] [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 cross-sections of a portion of the display area 235, a portion of the cathode contact area 234, a portion of the peripheral circuit area 233, and a portion of the area including the FPC 124.

[0061] 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. In Figure 1B, the light-emitting element 170 of pixel 230R is shown as light-emitting element 170R, the light-emitting element 170 of pixel 230G is shown as light-emitting element 170G, and the light-emitting element 170 of pixel 230B is shown as light-emitting element 170B.

[0062] In this specification and elsewhere, the electrodes 171, EL layer 172, and electrode 173 of the light-emitting element 170R may be referred to as electrode 171R, EL layer 172R, and electrode 173R. The electrodes 171, EL layer 172, and electrode 173 of the light-emitting element 170G may be referred to as electrode 171G, EL layer 172G, and electrode 173G. The electrodes 171, EL layer 172, and electrode 173 of the light-emitting element 170B may be referred to as electrode 171B, EL layer 172B, and electrode 173B.

[0063] The light-emitting element 170R has the function of emitting light 175R. The light-emitting element 170G has the function of emitting light 175G. The light-emitting element 170B has the function of emitting light 175B. For example, light 175R is red light, light 175G is green light, and light 175B is blue light.

[0064] Furthermore, pixels 230R, 230G, and 230B each have a transistor 251 for driving the display element. Transistor 251 is a transistor (also called a driving transistor) that controls the current flowing to the light-emitting element 170.

[0065] Furthermore, peripheral circuit regions 232 and 233 contain multiple transistors. In Figure 1B, transistor 252 is shown as an example of a transistor included in peripheral circuit region 233.

[0066] The display device 100 has transistors 251, 252, light-emitting elements 170, etc., between substrates 111 and 121. Substrates 111 and 121 overlap via an adhesive layer 142.

[0067] 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.

[0068] Transistors 251 and 252 are provided on the substrate 111 via insulating layers 112 and 113. Transistors 251 and 252 are also covered by insulating layers 210 and 213. An insulating layer 114 is provided on insulating layer 213. Preferably, insulating layer 114 functions as a planarization layer. A "planarization layer" refers to a layer having a surface with reduced irregularities on the formed surface. An insulating layer 139 is provided on insulating layer 114.

[0069] The number of insulating layers covering the transistors is not limited and may be a single layer or two or more layers. It is preferable to use a material that does not easily allow impurities such as water and hydrogen to diffuse in at least one of the insulating layers covering each transistor. This allows the insulating layer to function as a barrier film. With such a configuration, it is possible to effectively suppress the diffusion of impurities from the outside to the transistors, thereby realizing a highly reliable display device.

[0070] Figure 1C shows an enlarged view of transistor 252. Note that transistor 251 can have a similar structure to transistor 252.

[0071] In the pixel 230, the electrode 171 is provided on the insulating layer 139. The electrode 171 is electrically connected to either the source or drain of the transistor 251 at an opening provided in the insulating layer 114 and the insulating layer 139. The opening is also filled with layer 162. By filling the opening with layer 162, the step difference that occurs at the opening can be reduced, and the flatness of the EL layer 172 and the electrode 173 can be improved. Therefore, it is preferable that the upper surface of layer 162 and the upper surface of electrode 171 coincide or substantially coincide.

[0072] 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. A protective layer 126 is also provided on electrode 173. An insulating layer 115 is provided covering the light-emitting element 170 and the protective layer 126. Preferably, the insulating layer 115 covers the sides of the light-emitting element 170. Preferably, the insulating layer 115 is made of a material that is impermeable to hydrogen and moisture.

[0073] Furthermore, an insulating layer 116 is provided on the insulating layer 115. Preferably, the insulating layer 116 functions as a planarizing layer. A conductive layer 118 is provided on the insulating layer 116. The conductive layer 118 is electrically connected to the electrode 173. The conductive layer 118 is electrically connected to multiple electrodes 173 and functions as a common electrode. In addition, the conductive layer 118 is electrically connected to the electrode 181 in the cathode contact region 234.

[0074] Furthermore, the conductive layer 118 functions as an auxiliary conductive layer for the electrode 173. By providing the conductive layer 118, the potential variation of the 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. In addition, the conductive layer 118 is electrically connected to the electrode 181. A constant potential is supplied to the electrode 181. Therefore, a constant potential is supplied to the electrode 173 via the conductive layer 118.

[0075] Furthermore, the display device 100 shown in Figure 1B has electrodes 228 and 229. Electrode 228 is provided on the insulating layer 211. Electrode 228 is electrically connected to the peripheral drive circuit. Electrode 229 is electrically connected to electrode 228 through an opening provided in the insulating layer 210. The FPC 124 is also electrically connected to electrode 229 via a connecting layer 138.

[0076] As the connecting layer 138, an anisotropic conductive film (ACF), an anisotropic conductive paste (ACP), etc., can be used.

[0077] The light-emitting element 170 is, for example, a top-emission type light-emitting element. When 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. Therefore, the light 175 is emitted from the electrode 173 side. Also, if the conductive layer 118 is provided covering the light-emitting element 170, the conductive layer 118 also has the function of transmitting visible light.

[0078] 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, an electron blocking material, a material with high electron transport properties, a material with high electron injection properties, or a bipolar material (a material with high electron transport and hole transport properties).

[0079] 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.

[0080] There are two methods for achieving color display: one involves combining a white-emitting light-emitting element 170 with a colored layer (color filter), 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 obtain a light-emitting color with higher color purity than the former method. In addition to the latter method, color purity can be further improved by adding a microcavity structure to the light-emitting element 170.

[0081] 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.

[0082] 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.

[0083] Color display can be achieved by controlling the brightness of light 175 (light 175R, light 175G, and light 175B) for each pixel. The hues of the emitted colors combined to achieve color display are not limited to combinations of red, green, and blue, but may also be combinations of yellow, cyan, and magenta. The hues of the emitted colors to be combined should be set appropriately according to the purpose or application.

[0084] [substrate] There are no major restrictions on the materials used for substrates 111 and 121. Depending on the purpose, the materials should be determined 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.

[0085] 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.

[0086] 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.

[0087] 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.

[0088] 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.

[0089] 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 -5 Any 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.

[0090] [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.

[0091] 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.

[0092] 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.

[0093] 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.

[0094] 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.

[0095] 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).

[0096] 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.

[0097] [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.

[0098] 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).

[0099] 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.

[0100] 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.

[0101] 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.

[0102] 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.

[0103] Furthermore, CMP treatment may be performed on 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.

[0104] [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.

[0105] 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.

[0106] [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.

[0107] 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.

[0108] 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.

[0109] <Metal oxides> Here, we will explain metal oxides that can be used as oxide semiconductors.

[0110] 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.

[0111] 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.

[0112] 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.

[0113] <Classification of crystal structures> First, we will explain the classification of crystal structures in oxide semiconductors using Figure 23A. Figure 23A is a diagram illustrating the classification of crystal structures in oxide semiconductors, specifically IGZO (a metal oxide containing In, Ga, and Zn).

[0114] As shown in Figure 23A, oxide semiconductors are broadly classified into "Amorphous," "Crystalline," and "Crystal." "Amorphous" includes completely amorphous materials. "Crystalline" includes CAAC (c-axis-aligned crystalline), nc (nanocrystalline), and CAC (cloud-aligned composite) (excluding single crystal and polycrystal). Note that single crystal, polycrystal, and completely amorphous materials are excluded from the "Crystalline" classification. "Crystal" includes single crystal and polycrystal materials.

[0115] The structure within the thick frame shown in Figure 23A 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.

[0116] The crystal structure of a film or substrate can be evaluated using X-ray diffraction (XRD) spectroscopy. Figure 23B shows the XRD spectrum obtained by GIXD (Grazing-Incidence XRD) measurement of a CAAC-IGZO film classified as "Crystalline". The horizontal axis represents 2θ [deg.], and the vertical axis represents intensity [au]. 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 23B may simply be referred to as the XRD spectrum in this specification. The composition of the CAAC-IGZO film shown in Figure 23B is approximately In:Ga:Zn = 4:2:3 [atomic ratio]. The thickness of the CAAC-IGZO film shown in Figure 23B is 500 nm.

[0117] As shown in Figure 23B, 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 23B, the peak near 2θ=31° is asymmetrical with respect to the angle at which the peak intensity was detected.

[0118] 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 23C. Figure 23C 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 23C 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.

[0119] As shown in Figure 23C, the diffraction pattern of the CAAC-IGZO film shows multiple spots indicating c-axis orientation.

[0120] <Oxide semiconductor structure> Note that when focusing on the crystal structure, oxide semiconductors may be classified differently from those shown in Figure 23A. 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.

[0121] Here, we will explain the details of the CAAC-OS, nc-OS, and a-like OS mentioned above.

[0122] [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.

[0123] 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.

[0124] 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.

[0125] 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.

[0126] 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.

[0127] 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.

[0128] 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.

[0129] 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.

[0130] [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.

[0131] [a-like OS] a-like OS is an oxide semiconductor having a structure between nc-OS and amorphous oxide semiconductors. a-like OS has porous or low-density regions. That is, a-like OS has lower crystallinity compared to nc-OS and CAAC-OS. Also, a-like OS has a higher hydrogen concentration in the film compared to nc-OS and CAAC-OS.

[0132] <Oxide semiconductor structure> Next, we will explain the details of CAC-OS mentioned above. Note that CAC-OS refers to the material composition.

[0133] [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.

[0134] 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.

[0135] 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.

[0136] 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.

[0137] Furthermore, a clear boundary may not be observed between the first region and the second region described above.

[0138] 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.

[0139] When using CAC-OS in a transistor, the conductivity caused by the first region and the insulating property caused by the second region act complementarily, enabling the function of switching (on / off function) to be imparted to the CAC-OS. That is, CAC-OS has a conductive function in a part of the material and an insulating function in a part of the material, and has a function as a semiconductor in the whole material. By separating the conductive function and the insulating function, both functions can be enhanced to the maximum extent. Therefore, by using CAC-OS in a transistor, a high on-current (I on ), a high field-effect mobility (μ), and a good switching operation can be realized.

[0140] Oxide semiconductors have various structures and each has different characteristics. The oxide semiconductor according to one aspect of the present invention may have two or more of an amorphous oxide semiconductor, a polycrystalline oxide semiconductor, an a-like OS, a CAC-OS, an nc-OS, and a CAAC-OS.

[0141] <Transistor having an oxide semiconductor> Subsequently, the case of using the above oxide semiconductor in a transistor will be described.

[0142] By using the above oxide semiconductor in a transistor, a transistor with a high field-effect mobility can be realized. Also, a highly reliable transistor can be realized.

[0143] It is preferable to use an oxide semiconductor with a low carrier concentration in 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, and even more preferably 1×10 10 cm -3It is less than 1 × 10 -9 cm -3 This concludes the explanation. Furthermore, when lowering the carrier concentration of an oxide semiconductor film, the impurity concentration in the oxide semiconductor film should be lowered to reduce the defect level density. In this specification, a low impurity concentration and low defect level density are referred to as high-purity intrinsic or substantially high-purity intrinsic. Note that oxide semiconductors with low carrier concentrations are sometimes referred to as high-purity intrinsic or substantially high-purity intrinsic oxide semiconductors.

[0144] Furthermore, oxide semiconductor films that are highly pure or substantially highly pure have a low defect level density, which may result in a low trap level density.

[0145] Furthermore, charges trapped in the trap levels of oxide semiconductors can take a long time to disappear, sometimes behaving like fixed charges. Therefore, transistors in which channel formation regions are formed in oxide semiconductors with a high trap level density may exhibit unstable electrical properties.

[0146] Therefore, reducing the impurity concentration in the oxide semiconductor is effective in stabilizing the electrical characteristics of the transistor. Furthermore, in order to reduce the impurity concentration in the oxide semiconductor, it is preferable to also reduce the impurity concentration in adjacent films. Examples of impurities include hydrogen, nitrogen, alkali metals, alkaline earth metals, iron, nickel, and silicon.

[0147] <Impurities> Here, we will explain the effects of various impurities in oxide semiconductors.

[0148] 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. 18atoms / cm 3 The following is preferably 2 × 10 17 atoms / cm 3 The following applies:

[0149] 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:

[0150] 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 × 10⁻¹⁰ 19 atoms / cm 3 Less than 5 × 10 18 atoms / cm 3 More preferably 1 × 10 18 atoms / cm 3 More preferably 5 × 10 17 atoms / cm 3 Do the following:

[0151] 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.

[0152] By using an oxide semiconductor with sufficiently reduced impurities in the channel formation region of a transistor, stable electrical characteristics can be provided.

[0153] <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.

[0154] 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, it is possible to provide a transistor with a large on-current.

[0155] 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.

[0156] 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).

[0157] [Variation 1] Figure 2 shows a schematic cross-sectional view of a modified display device 100A, which is a modified version of the display device 100. The display device 100A differs from the display device 100 in that it does not have an insulating layer 115. For example, by forming the insulating layer 116 with a material that is impermeable to hydrogen and moisture, the formation of the insulating layer 115 can be omitted.

[0158] [Variation 2] Figure 3 shows a schematic cross-sectional view of display device 100B, which is a modified version of display device 100. Display device 100B differs from display device 100 in that the insulating layer 116 in the region overlapping with the light-emitting element 170 is removed, and the upper surface of the insulating layer 116 and the upper surface of the insulating layer 115 coincide or nearly coincide. Such a structure can be achieved by performing an anisotropic etching treatment using a dry etching method or the like after the formation of the insulating layer 116.

[0159] In the display device 100B shown in Figure 3, the insulating layer 116 in the region overlapping with the light-emitting element 170 is removed, and the conductive layer 118 and the insulating layer 115 are in contact in that region. By removing the insulating layer 116 in the region overlapping with the light-emitting element 170, the display device 100B can be made thinner. Furthermore, the weight of the display device 100B can be reduced.

[0160] [Variation 3] Figure 4 shows a cross-section of a modified display device 100C, which is a modified version of the display device 100. The display device 100C has an insulating layer 122, a colored layer 131 (colored layer 131R, colored layer 131G, and colored layer 131B), a light-shielding layer 132, and an insulating layer 133 provided on a substrate 121. The insulating layer 133 may also function as a planarizing layer.

[0161] The colored layer 131R has the function of transmitting the red color gamut, the colored layer 131G has the function of transmitting the green color gamut, and the colored layer 131B has the function of transmitting the blue color gamut. When the colored layer 131 and the light-shielding layer 132 are provided, a region is formed around the colored layer 131 where the colored layer 131 and the light-shielding layer 132 overlap each other.

[0162] Furthermore, the colored layer 131R has a region that overlaps with the light-emitting element 170R, the colored layer 131G has a region that overlaps with the light-emitting element 170G, and the colored layer 131B has a region that overlaps with the light-emitting element 170B. By layering the colored layer 131 and the light-emitting element 170, the color purity of the light 175 can be increased.

[0163] [Variation 4] Figure 5 shows a cross-section of the display device 100D, which is a modified version of the display device 100. The display device 100D differs from the display device 100 in that it has a microlens array 245 on the substrate 121. The microlens array 245 comprises multiple microlenses, which are arranged in overlap with the pixels 230. The light 175 emitted from the light-emitting element 170 is focused by the microlens array 245. This makes it possible to increase the light extraction efficiency of the display device.

[0164] [Variation 5] Figure 6 shows a cross-section of a modified display device 100E, which is a variation of the display device 100D. The microlens array 245 may be provided between the substrate 121 and the adhesive layer 142. In the configuration shown in Figure 6, it is preferable that the refractive index of the microlens array 245 is greater than the refractive index of the adhesive layer 142.

[0165] [Variation 6] Figure 7 shows a cross-section of display device 100F, a modified version of display device 100. Display device 100F has a configuration that combines display device 100C and display device 100D. By using both the colored layer 131 and the microlens array 245, a display device with higher display quality can be realized.

[0166] [Variation 7] Figure 8 shows a cross-section of display device 100G, a modified version of display device 100. Display device 100G has a configuration that combines display device 100C and display device 100E. By using both the colored layer 131 and the microlens array 245, a display device with higher display quality can be realized.

[0167] [Variation 8] The display device 100 is not limited to a top-emission type display device, but may also be a bottom-emission type display device. Figure 9 shows a cross-section of a modified display device 100H, which is a modified version of the display device 100. The display device 100H is a bottom-emission type display device having a light-emitting element 170 with a bottom-emission structure.

[0168] The bottom-emission structure (bottom-exjection structure) light-emitting element 170 has an electrode 171 made of a conductive material that transmits visible light and an electrode 173 made of a conductive material that reflects visible light.

[0169] Furthermore, the light-emitting element 170 can also be a light-emitting element with a dual emission structure (double-sided injection structure). If the light-emitting element 170 is a light-emitting element with a dual emission structure, both electrodes 171 and 173 should be made of a conductive material that transmits visible light.

[0170] [Variation 9] Figure 10 shows a cross-section of a modified display device 100I, which is a modified version of the display device 100. The display device 100I includes a touch sensor 370 between the substrate 121 and the adhesive layer 142. 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.

[0171] 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.

[0172] 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.

[0173] 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.

[0174] 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.

[0175] The other components are the same as those of the display device 100, so a detailed explanation will be omitted.

[0176] 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.

[0177] <<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 and the cathode contact area 234.

[0178] 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.

[0179] 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.

[0180] 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.

[0181] 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.

[0182] CVD and ALD methods allow for control of 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 changing the flow rate ratio of the source gases during film deposition. When depositing films while changing the flow rate ratio of the source gases, the time required for film deposition can be reduced compared to depositing films using multiple deposition chambers, by eliminating the time spent on transport and pressure adjustment. Therefore, it may be possible to increase the productivity of semiconductor devices.

[0183] Furthermore, when forming a film using the ALD method, it is preferable to use a chlorine-free gas as the material gas.

[0184] 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 -5It 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.

[0185] 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.

[0186] 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.

[0187] When processing the layers (thin films) that make up the display device, photolithography or the like can be used. Alternatively, island-like layers may be formed by a film deposition method using a shielding mask. Alternatively, the layers may be processed by nanoimprint, sandblasting, lift-off, or the like. 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.

[0188] 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.

[0189] 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.

[0190] The display device 100 is manufactured by combining the element substrate 151 (see Figure 22A) and the substrate 121.

[0191] [Element substrate 151] An example of a method for manufacturing the element substrate 151 will be described.

[0192] [Process 1] Insulating layers 112 and 113 are formed on the substrate 111 (see Figure 11A). Insulating layers 112 and 113 may each be laminates of multiple insulating layers.

[0193] For example, inorganic insulating films such as silicon nitride film, silicon oxide nitride film, silicon oxide film, silicon nitride oxide film, aluminum oxide film, and aluminum nitride film can be used as insulating layers 112 and 113. In addition, inorganic insulating films such as 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 laminated together. It is also preferable that at least one of insulating layers 112 and 113 is made of a material that is impermeable to impurities such as hydrogen and water.

[0194] 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.

[0195] [Process 2] 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.

[0196] [Process 3] Next, an insulating layer 211 is formed on the insulating layer 113 and the electrode 221. The insulating layer 211 can be made of the same material as the insulating layer 112 or the insulating layer 113. The insulating layer 211 may also be a laminate of multiple insulating layers.

[0197] 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.

[0198] 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.

[0199] [Step 4] 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.

[0200] 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.

[0201] 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%.

[0202] The oxide semiconductor film preferably contains at least indium or zinc. It is particularly preferable that it contains both indium and zinc.

[0203] 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.

[0204] In particular, semiconductor materials with an energy gap of 2.5 eV or higher are preferred because they have high transmittance of visible light.

[0205] Oxide semiconductor films can be formed by sputtering. Other methods such as PLD, PECVD, thermal CVD, ALD, and vacuum deposition may also be used.

[0206] [Step 5] Next, electrodes 224a, 224b, and wiring 125 are formed (see Figure 11B). 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.

[0207] 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.

[0208] [Step 6] 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.

[0209] [Step 7] 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.

[0210] [Step 8] Next, an insulating layer 213 is formed (see Figure 11C). 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.

[0211] 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.

[0212] [Step 9] Next, an insulating layer 114 is formed. Preferably, the insulating layer 114 functions as a planarizing layer.

[0213] [Step 10] Next, an insulating layer 139 is formed. The insulating layer 139 is the layer to be formed on the display element that will be formed later. The insulating layer 139 also functions as an etching stopper when etching parts of the electrode 171, EL layer 172, and electrode 173 that will be etched later.

[0214] In particular, the insulating layer 139 is made of a material that is difficult to etch during the etching process of the electrode 173. When etching of the electrode 173 is performed by a dry etching method, or when dry etching is the primary method, it is preferable to provide the insulating layer 139. By providing the insulating layer 139, the degree of freedom in process design can be increased, and productivity and reliability can be improved.

[0215] [Step 11] Next, portions of the insulating layer 139, insulating layer 114, insulating layer 213, and insulating layer 210 are removed to form an opening 161 that reaches the electrode 224a.

[0216] [Step 12] Next, an electrode 171 is formed on the insulating layer 139 (see Figure 12B). The electrode 171 is formed using a conductive material that reflects visible light. When the electrode 171 is used as an anode, it can be made into a laminated structure of, for example, ITO and silver. Alternatively, it can be made into a laminated structure with silver sandwiched between two layers of ITO.

[0217] [Step 13] Next, a layer 162 is provided inside the opening 161 so as to fill the opening 161. By providing a layer 162 in the opening 161, the unevenness of the upper surface is reduced, and the coverage of the insulating layer and conductive layer that are later formed can be improved. Therefore, it is preferable that the upper surface of the layer 162 and the upper surface of the electrode 171 coincide or substantially coincide.

[0218] Materials that can be used for layer 162 include epoxy resin, acrylic resin, silicone resin, phenolic resin, polyimide resin, imide resin, PVC (polyvinyl chloride) resin, PVB (polyvinyl butyral) resin, and EVA (ethylene vinyl acetate) resin. Alternatively, a photoresist may be used as layer 162. The photoresist used as layer 162 may be a positive-type photoresist or a negative-type photoresist.

[0219] [Step 14] Next, the EL layer 172 is formed (see Figure 13A). In this step, the EL layer 172 is formed from an organic EL material containing a red light emitting material. 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.

[0220] [Step 15] Next, electrode 173 is formed. Electrode 173 is formed using a conductive material that transmits visible light. Furthermore, when electrode 173 is used as a cathode, it can be formed as a laminated structure of, for example, lithium fluoride and a light-transmitting conductive material such as ITO.

[0221] [Step 16] Next, a protective layer 126 is formed. The protective layer 126 is formed using a material that transmits visible light. For example, materials such as silicon oxide, silicon nitride, aluminum oxide, or oxide semiconductors can be used as the protective layer 126. The protective layer 126 may be a single layer or a multilayer structure. For example, the protective layer 126 may be a multilayer structure of aluminum oxide and silicon nitride, or a multilayer structure of aluminum oxide and an oxide semiconductor (e.g., IGZO).

[0222] The protective layer 126 can be formed by, for example, sputtering, ALD (including thermal ALD and PEALD), or vacuum deposition. It is preferable to use a formation method that minimizes damage to the underlying EL layer. Therefore, the protective layer 126 is preferably formed by ALD or vacuum deposition rather than sputtering. If the protective layer 126 is to be a multi-layered structure, the layer in contact with the electrode 173 may be formed by ALD, while the other layers may be formed by sputtering.

[0223] [Step 17] Next, a resist mask 261 is formed on the protective layer 126 using a multi-gradation mask (see Figure 13B).

[0224] Here, we will explain multi-gradation masks using Figure 24. A multi-gradation mask is an exposure mask that allows for three exposure levels in the exposed area, the intermediate exposed area, and the unexposed area, resulting in transmitted light of multiple intensities. It is possible to form a resist mask with multiple (typically two) thicknesses in a single exposure and development process. Therefore, by using a multi-gradation mask, the number of exposure masks (photomasks) can be reduced.

[0225] Typical examples of multi-tone masks include the gray tone mask 304 shown in Figure 24A1 and the halftone mask 314 shown in Figure 24B1.

[0226] As shown in Figure 24A1, the gray tone mask 304 is composed of a translucent substrate 301, a light-shielding portion 302 formed thereon, and a diffraction grating 303. In the light-shielding portion 302, the light transmittance is 0%. On the other hand, the diffraction grating 303 can control the light transmittance by setting the spacing between light-transmitting portions such as slits, dots, and meshes to a spacing less than or equal to the resolution limit of the light used for exposure. The diffraction grating 303 can be either periodic slits, dots, or meshes, or aperiodic slits, dots, or meshes.

[0227] As the translucent substrate 301, a translucent substrate such as quartz can be used. The light-shielding portion 302 and the diffraction grating 303 can be formed using a light-absorbing light-shielding material such as chromium or chromium oxide.

[0228] When exposure light is shone onto the gray tone mask 304, as shown in Figure 24A2, the light transmittance is 0% in the light-shielding section 302, and 100% in the areas where neither the light-shielding section 302 nor the diffraction grating 303 is provided. Furthermore, the light transmittance can be adjusted within the range of 10 to 70% by the diffraction grating 303. The adjustment of the light transmittance in the diffraction grating 303 is possible by adjusting the spacing and pitch of the slits, dots, or mesh of the diffraction grating.

[0229] As shown in Figure 24B1, the halftone mask 314 consists of a translucent substrate 311 and a semi-transparent portion 312 and a light-shielding portion 313 formed thereon. The semi-transparent portion 312 can be made of MoSiN, MoSi, MoSiO, MoSiON, CrSi, etc. The light-shielding portion 313 can be formed using a light-absorbing light-shielding material such as chromium or chromium oxide.

[0230] When exposure light is shone on the halftone mask 314, as shown in Figure 24B2, the light transmittance is 0% in the light-shielding portion 313, and 100% in the region where neither the light-shielding portion 313 nor the semi-transparent portion 312 is provided. Furthermore, the light transmittance can be adjusted within the range of 10 to 70% by the semi-transparent portion 312. The light transmittance in the semi-transparent portion 312 can be adjusted by the material used for the semi-transparent portion 312.

[0231] The resist mask 261 formed using a multi-gradation mask is a resist mask consisting of multiple regions of different thicknesses, and in this embodiment, it has two regions: a thick region and a thin region. In this embodiment, the thick region of the resist mask 261 is shown as resist mask 261a, and the thin region is shown as resist mask 261b.

[0232] In this process, a thick resist mask 261 is formed in the region that will become the light-emitting element 170R in a later process (resist mask 261a), and a thin resist mask 261 is formed in the other regions (resist mask 261b).

[0233] [Step 18] Next, the resist mask 261 (resist mask 261a and resist mask 261b) is used as a mask to selectively remove the protective layer 126, electrode 173, EL layer 172, and a portion of electrode 171 (see Figure 14A). Etching of the protective layer 126, electrode 173, EL layer 172, and electrode 171 can be performed using dry etching, wet etching, or other methods. These etching methods may also be used in combination. Note that during etching of electrode 171, a portion of the exposed insulating layer 139 may be etched.

[0234] This process forms the light-emitting element 170R. In Figure 14A, the electrodes 171, EL layer 172, and 173 of the light-emitting element 170R are shown as electrode 171R, EL layer 172R, and electrode 173R. The protective layer 126 that overlaps with the light-emitting element 170R is shown as protective layer 126R.

[0235] When viewed from above, the shapes of the light-emitting element 170R, including the protective layer 126R, electrode 173R, EL layer 172R, and electrode 171R, are roughly identical. Furthermore, the side surfaces of the protective layer 126R, electrode 173R, EL layer 172R, and electrode 171R are roughly identical. The protective layer 126R acts as a mask during etching of electrode 173R, EL layer 172R, and electrode 171R. Therefore, this process can also be called self-aligned patterning. The same applies to the light-emitting elements 170G and 170B, which will be described later.

[0236] In addition, the protective layer 126, electrode 173, EL layer 172, and a portion of electrode 171 that overlap the cathode contact region 234 are selectively removed. In the cathode contact region 234, a portion of electrode 171 is selectively removed to form electrode 181.

[0237] [Step 19] Next, the thickness of the resist mask 261a is reduced using an ashing process with oxygen plasma or the like. At this time, the resist mask 261b, which is thinner than the resist mask 261a, is removed, and the protective layer 126 of the area covered by the resist mask 261b is exposed (see Figure 14B).

[0238] In step 17, when the resist mask is prepared, the resist mask in the area that will become the light-emitting element 170R is prepared thickly, so that the resist mask 261 (resist mask 261a) on the light-emitting element 170R remains. However, this step may expose the protective layer 126 adjacent to the outer periphery of the resist mask 261a.

[0239] [Step 20] Next, the area where the protective layer 126 was exposed in the previous step, along with the electrode 173 and EL layer 172 overlapping that area, are removed, exposing the electrode 171 and electrode 181 overlapping that area (see Figure 15A).

[0240] At this time, the peripheral portions of the protective layer 126R, the electrode 173R, and the EL layer 172R may also be removed. Therefore, the end portion of the electrode 171R may extend beyond the end portions of the protective layer 126R, the electrode 173R, and the EL layer 172R, respectively.

[0241] [Step 21] Next, the resist mask 261a is removed. The removal of the resist mask 261a may be performed by a dry etching method or a wet etching method. For example, the resist mask 261a may be removed by an ashing process using oxygen plasma, or the resist mask 261a may be removed using a stripping solution or the like.

[0242] [Step 22] Next, the EL layer 172 is formed (see FIG. 15B). The formation of the EL layer 172 may be performed in the same manner as in Step 14. However, in this step, the EL layer 172 is formed of an organic EL material containing a light-emitting material for green light.

[0243] [Step 23] Next, the electrode 173 is formed. The formation of the electrode 173 may be performed in the same manner as in Step 15.

[0244] [Step 24] Next, the protective layer 126 is formed. The formation of the protective layer 126 may be performed in the same manner as in Step 16.

[0245] [Step 25] Next, a resist mask 261 is formed on the protective layer 126 using a multi-tone mask (see FIG. 16A). The formation of the resist mask 261 is performed in the same manner as in Step 17. However, in this step, the resist mask for the region that will become the light-emitting element 170G in a later step is formed thick (resist mask 261a), and the resist mask 261 for other regions is formed thin (resist mask 261b).

[0246] [Step 26] Next, the resist mask 261 is used as a mask to selectively remove the protective layer 126, electrode 173, EL layer 172, and a portion of electrode 171 (see Figure 16B). Etching of the protective layer 126, electrode 173, EL layer 172, and electrode 171 can be carried out in the same manner as in step 18.

[0247] This process forms the light-emitting element 170G. In Figure 16B, the electrodes 171, EL layer 172, and electrode 173 of the light-emitting element 170G are shown as electrode 171G, EL layer 172G, and electrode 173G. The protective layer 126 that overlaps with the light-emitting element 170G is shown as protective layer 126G.

[0248] Furthermore, this process may etch the edges of electrode 171R, causing the edges of the protective layer 126R, electrode 173R, EL layer 172R, and electrode 171R to coincide or nearly coincide.

[0249] [Step 27] Next, similar to step 19, the thickness of the resist mask 261a is reduced using an ashing process with oxygen plasma. At this time, the resist mask 261b is removed, and the protective layer 126 of the area covered by the resist mask 261b is exposed (see Figure 17A).

[0250] In step 25, when the resist mask is prepared, the resist mask in the area that will become the light-emitting element 170G is prepared thickly, so that the resist mask 261 (resist mask 261a) on the light-emitting element 170G remains. However, this step may expose the protective layer 126 adjacent to the outer periphery of the resist mask 261a.

[0251] [Step 28] Next, the region where the protective layer 126 was exposed in the previous step, along with the electrode 173 and EL layer 172 overlapping that region, are removed, exposing the electrode 171 and electrode 181 overlapping that region. The removal of the electrode 173 and EL layer 172 overlapping that region is performed under conditions that the protective layer 126R is not removed.

[0252] At this time, the peripheral portions of the protective layer 126G, electrode 173G, and EL layer 172G may also be removed. As a result, the end of electrode 171G may extend beyond the respective ends of the protective layer 126G, electrode 173G, and EL layer 172G.

[0253] [Step 29] Next, the resist mask 261a is removed. The resist mask 261a may be removed by dry etching or by wet etching. For example, the resist mask 261a may be removed by ashing with oxygen plasma, or by using a stripping solution.

[0254] [Step 30] Next, the EL layer 172 is formed (see Figure 18A). The formation of the EL layer 172 can be carried out in the same manner as in step 14 or step 22. However, in this step, the EL layer 172 is formed from an organic EL material containing a blue light emitting material.

[0255] [Step 31] Next, electrode 173 is formed. The formation of electrode 173 can be carried out in the same manner as in step 15 or step 23.

[0256] [Step 32] Next, a protective layer 126 is formed. The protective layer 126 can be formed in the same manner as in step 16 or step 24.

[0257] [Step 33] Next, a resist mask 261 is formed on the protective layer 126 using a multi-gradation mask (see Figure 18B). The formation of the resist mask 261 is carried out in the same manner as in step 17 or step 25. However, in this step, the resist mask is formed thickly in the area that will become the light-emitting element 170B in a later step (resist mask 261a), and the resist mask 261 in the other areas is formed thinly (resist mask 261b).

[0258] [Step 34] Next, using the resist mask 261 as a mask, the protective layer 126, the electrode 173, the EL layer 172, and a part of the electrode 171 are selectively removed (see Fig. 19A). The etching of the protective layer 126, the electrode 173, the EL layer 172, and the electrode 171 may be performed in the same manner as in Step 18 or Step 26.

[0259] By this step, the light-emitting element 170B is formed. In Fig. 19A, the electrode 171, the EL layer 172, and the electrode 173 included in the light-emitting element 170B are shown as the electrode 171B, the EL layer 172B, and the electrode 173B. Also, the protective layer 126 overlapping with the light-emitting element 170B is shown as the protective layer 126B.

[0260] Also, by this step, the end portion of the electrode 171G may be etched so that the end portions of the protective layer 126G, the electrode 173G, the EL layer 172G, and the electrode 171G coincide or substantially coincide.

[0261] [Step 35] Next, in the same manner as in Step 19 or Step 27, the thickness of the resist mask 261a is reduced using ashing treatment with oxygen plasma or the like. At this time, the resist mask 261b is removed, and the protective layer 126 in the region covered by the resist mask 261b is exposed (see Fig. 19B).

[0262] When providing the resist mask in Step 33, by providing the resist mask in the region where the light-emitting element 170B is to be formed to be thick, the resist mask 261 (resist mask 261a) on the light-emitting element 170B remains. However, by this step, the protective layer 126 adjacent to the outer peripheral portion of the resist mask 261a may be exposed.

[0263] [Step 36] Next, the region where the protective layer 126 was exposed in the previous step, the electrode 173 and the EL layer overlapping with the region are removed, and the electrode 171 and the electrode 181 overlapping with the region are exposed (see Fig. 20A). The removal of the electrode 173 and the EL layer overlapping with the region is performed under the condition that the protective layer 126R and the protective layer 126G are not removed.

[0264] At this time, the peripheral portions of the protective layer 126B, electrode 173B, and EL layer 172B may also be removed. As a result, the end of electrode 171B may extend beyond the respective ends of the protective layer 126B, electrode 173B, and EL layer 172B.

[0265] [Step 37] Next, the resist mask 261a is removed. The resist mask 261a may be removed by dry etching or by wet etching. For example, the resist mask 261a may be removed by ashing with oxygen plasma, or by using a stripping solution.

[0266] [Step 38] Next, an insulating layer 115 is formed (see Figure 20B). As mentioned above, it is preferable that the insulating layer 115 covers the sides of the light-emitting element 170. It is also preferable that the insulating layer 115 be formed from a material that is impermeable to hydrogen and moisture. For example, aluminum oxide is formed as the insulating layer 115 by the ALD method.

[0267] [Step 39] Next, an insulating layer 116 is formed on the insulating layer 115 (see Figure 21A). Preferably, the insulating layer 116 functions as a planarization layer. If the light emitted from the light-emitting element 170 is emitted to the outside from the insulating layer 116 side, a light-transmitting material is used for the insulating layer 116. Furthermore, by using a photosensitive material for the insulating layer 116, the subsequent formation of the opening can be performed without using a resist mask.

[0268] In this embodiment, a photosensitive acrylic resin or a photosensitive polyimide is used as the insulating layer 116.

[0269] [Step 40] Next, openings 163 are formed in the region overlapping with the light-emitting element 170 and the region overlapping with the electrode 181, respectively (see Figure 21B). As mentioned above, by using a photosensitive material for the insulating layer 116, openings 163 can be formed in the insulating layer 116 without using a resist mask. Specifically, an opening is formed in the insulating layer 116, and the insulating layer 115 and protective layer 126 in the region overlapping with the opening are removed using the insulating layer 116 as a mask.

[0270] Therefore, in the display area 235, the electrode 173 is exposed at the bottom of the opening 163. Also, in the cathode contact area 234, the electrode 181 is exposed at the bottom of the opening 163.

[0271] [Step 41] Next, a conductive layer 118 is formed. If the conductive layer 118 covers the light-emitting element 170 and the light emitted from the light-emitting element 170 is emitted to the outside from the conductive layer 118 side, a translucent material is used as the conductive layer 118. In this embodiment, ITO is used as the conductive layer 118.

[0272] Furthermore, if the conductive layer 118 covers only a portion of the light-emitting element 170, a material that does not have light transmission may be used as the conductive layer 118.

[0273] In the display area 235, the conductive layer 118 and the electrode 173 are electrically connected at the opening 163. Also, in the cathode contact area 234, the conductive layer 118 and the electrode 181 are electrically connected at the opening 163. Therefore, the electrode 173 is electrically connected to the electrode 181 via the conductive layer 118.

[0274] As described above, the element substrate 151 can be manufactured (see Figure 22A). In this embodiment, the manufacturing order of the light-emitting elements that function as display elements was described as light-emitting element 170R, light-emitting element 170G, and light-emitting element 170B. However, the manufacturing method of the display device according to one aspect of the present invention is not limited to this. The manufacturing order of the light-emitting elements may be, for example, light-emitting element 170B, light-emitting element 170G, and light-emitting element 170R, or for example, light-emitting element 170G, light-emitting element 170B, and light-emitting element 170R.

[0275] [Display device 100] Next, a method for manufacturing the display device 100 using the element substrate 151 and substrate 121 will be described.

[0276] The element substrate 151 and the substrate 121 are bonded together with an adhesive layer 142 in between. If a colored layer 131 is formed on the substrate 121, as in the display device 100C, the substrates are bonded together so that the light-emitting area of ​​the light-emitting element 170 overlaps with the colored layer 131.

[0277] The display device 100 can be manufactured in the manner described above (see Figures 1B and 22B).

[0278] According to one aspect of the present invention, the light-emitting element 170 can be formed using photolithography without using a metal mask. Therefore, the display device according to one aspect of the present invention has an MML structure. By using photolithography, it is possible to realize a display device with high resolution, which is difficult to achieve when using a metal mask.

[0279] Furthermore, by using a multi-level mask when forming a resist mask using photolithography, the number of photomasks required can be reduced. Therefore, the productivity of display devices can be increased.

[0280] This embodiment can be implemented in appropriate combination with the configurations described in other embodiments.

[0281] (Embodiment 2) In this embodiment, a more specific configuration example of the display device 100 will be described. Figure 25A 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.

[0282] 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 positions facing peripheral circuit area 232 across the display area 235. Similarly, some circuits may be provided at positions 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."

[0283] 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.

[0284] Furthermore, the display device 100 has m 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 wires 237, each arranged substantially parallel to the others and whose potential is controlled by circuits included in the peripheral circuit region 233.

[0285] The display area 235 has multiple pixels 230 arranged in a matrix. By combining the pixels 230 that control red light, 230 that control green light, and 230 that control blue light into a single pixel 240, and controlling the light emission amount (luminescence) of each pixel 230, full-color display can be achieved. Therefore, each of these three pixels 230 functions as a sub-pixel. That is, each of the three sub-pixels controls the light emission amount of red light, green light, or blue light (see Figure 25B1). 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 25B2).

[0286] Furthermore, the arrangement of the three pixels 230 that make up one pixel 240 may be a delta arrangement (see Figure 25B3). Specifically, the three pixels 230 that make up one pixel 240 may be arranged so that the lines connecting their respective center points form a triangle.

[0287] Furthermore, the areas of the three subpixels (pixel 230) do not have to be the same. If the luminous efficiency and reliability differ depending on the emission color, the area of ​​the subpixels may be changed for each emission color (see Figure 25B4). The subpixel arrangement shown in Figure 25B4 may also be called an "S-stripe arrangement".

[0288] Alternatively, the four subpixels may be combined and function as a single pixel. For example, a subpixel controlling white light may be added to the three subpixels that control red, green, and blue light respectively (see Figure 25B5). Adding a subpixel that controls white light can increase the brightness of the display area. Alternatively, a subpixel that controls yellow light may be added to the three subpixels that control red, green, and blue light respectively (see Figure 25B6). Alternatively, a subpixel that controls white light may be added to the three subpixels that control cyan, magenta, and yellow light respectively (see Figure 25B7).

[0289] By increasing the number of subpixels that function as a single pixel, and by appropriately combining subpixels that control light such as red, green, blue, cyan, magenta, and yellow, the reproduction of midtones can be improved. Therefore, the display quality can be enhanced.

[0290] Furthermore, a display device according to one aspect of the present invention can reproduce a variety of color gamuts. For example, it can reproduce color gamuts such as the PAL (Phase Alternating Line) and NTSC (National Television System Committee) standards used in television broadcasting, the sRGB (standard RGB) and Adobe RGB standards 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), the DCI-P3 (Digital Cinema Initiatives P3) standard used in digital cinema projection, and the ITU-R BT.2020 (REC.2020 (Recommendation 2020)) standard used in UHDTV (Ultra High Definition Television).

[0291] 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, 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.

[0292] <Example of circuit configuration for 230 pixels> Figure 26A shows an example of the circuit configuration of a pixel 230. The pixel 230 has a pixel circuit 431 and a display element 432.

[0293] 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. Similarly, 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. m and n are both integers greater than or equal to 1.

[0294] 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 the display element 432.

[0295] 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.

[0296] Transistor 436 has the function of controlling the writing of data signals to node 435.

[0297] 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.

[0298] The capacitive element 433 functions as a holding capacitor that holds the data written to node 435.

[0299] 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.

[0300] 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.

[0301] One of the anodes or cathodes of the display element 432 is electrically connected to the potential supply line VL_b, and the other is electrically connected to node 437.

[0302] As the display element 432, a light-emitting element such as an organic electroluminescent element (also called an organic EL element) can be used. However, the display element 432 is not limited to this, and for example, an inorganic EL element made of inorganic material may also be used. Note that "organic EL elements" and "inorganic EL elements" are sometimes collectively referred to as "EL elements".

[0303] The light-emitting color of an EL element can be white, red, green, blue, cyan, magenta, or yellow, depending on the materials that make up the EL element.

[0304] There are two methods for achieving color display: one involves combining a white-emitting display element 432 with a colored layer, and the other involves providing a display element 432 with a different emitting color for each pixel. The former method is more productive than the latter. On the other hand, the latter method requires manufacturing a different display element 432 for each pixel, making it less productive than the former method. However, the latter method can produce emitting colors with higher color purity than the former method. In addition to the latter method, color purity can be further improved by adding a microcavity structure to the display element 432.

[0305] The display element 432 may use either low-molecular-weight compounds or high-molecular-weight compounds, and may also contain inorganic compounds. The layers constituting the display element 432 can be formed by methods such as vapor deposition (including vacuum deposition), transfer, printing, inkjet, and coating.

[0306] The display element 432 may have an inorganic compound such as a quantum dot. For example, by using a quantum dot as the light-emitting layer, it can function as a light-emitting material.

[0307] 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.

[0308] 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.

[0309] In a display device having pixel circuits 431, the peripheral drive circuit sequentially selects the pixel circuits 431 of each row, turns on transistors 436 and 434, and writes a data signal to node 435.

[0310] 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 display element 432 emits light with a brightness corresponding to the amount of current flowing. By performing this sequentially for each row, an image can be displayed.

[0311] Figure 26B shows a modified version of the circuit configuration of pixel 230 shown in Figure 26A. In the circuit configuration shown in Figure 26B, the gate electrode of transistor 436 is electrically connected to the line to which the first scan signal is supplied (hereinafter referred to as scan line GL1_m). In addition, the gate electrode of transistor 434 is electrically connected to the line to which the second scan signal is supplied (hereinafter referred to as scan line GL2_m).

[0312] Furthermore, the circuit configuration shown in Figure 26B includes a transistor 438 in addition to the circuit configuration shown in Figure 26A. One of the source and drain electrodes of transistor 438 is electrically connected to the potential supply line V0, and the other is electrically connected to node 435. In addition, the gate electrode of transistor 438 is electrically connected to the line to which the third scanning signal is supplied (hereinafter referred to as the scanning line GL3_m).

[0313] Scan line GL1_m corresponds to wiring 236 shown in Figure 25A. Although Figure 25A does not show the wiring corresponding to scan lines GL2_m and GL3_m, scan lines GL2_m and GL3_m are electrically connected to the peripheral circuit region 232.

[0314] For example, to display pixel 230 in black, both transistors 434 and 438 are turned on. This makes the potential of the source electrode and gate electrode of transistor 251 equal. Therefore, the gate voltage of transistor 251 becomes 0V, and the current flowing to the display element 432 can be cut off.

[0315] Furthermore, some or all of the transistors constituting the pixel circuit 431 may be transistors having back gates. In the circuit configuration shown in Figure 26B, transistors having back gates are used as transistors. For example, transistors 434, 436, and 438 each show examples where the gate and back gate are electrically connected. Also, in the transistor 251 shown in Figure 26B, the back gate is electrically connected to node 437.

[0316] Figure 26C shows a modified version of the circuit configuration of pixel 230 shown in Figure 26A. The circuit configuration shown in Figure 26C is the same as the circuit configuration shown in Figure 26A, but without transistor 434 and the potential supply line V0. The other components can be understood by referring to the explanation of the circuit configuration shown in Figure 26A. Therefore, in order to reduce repetition of explanations, a detailed explanation of the circuit configuration shown in Figure 26C will be omitted.

[0317] Furthermore, as mentioned above, some or all of the transistors constituting the pixel circuit 431 may be transistors having back gates. For example, as shown in Figure 26D, a transistor having a back gate may be used for transistor 436, with the back gate and the gate electrically connected. Alternatively, as shown for transistor 251 in Figure 26D, the back gate and either the source or drain of the transistor may be electrically connected.

[0318] This embodiment can be implemented in appropriate combination with the configurations described in other embodiments.

[0319] (Embodiment 3) In this embodiment, a light-emitting element (also called a light-emitting device) that can be used in a display device according to one aspect of the present invention will be described.

[0320] <Example of light-emitting element configuration> As shown in Figure 27A, the light-emitting element 170 has an EL layer 172 between a pair of electrodes (electrode 171, electrode 173). The EL layer 172 can be composed of multiple layers, such as layer 4420, light-emitting layer 4411, and layer 4430. Layer 4420 may include, for example, a layer containing a material with high electron injection properties (electron injection layer) and a layer containing a material with high electron transport properties (electron transport layer). Light-emitting layer 4411 may include, for example, a light-emitting compound. Layer 4430 may include, for example, a layer containing a material with high hole injection properties (hole injection layer) and a layer containing a material with high hole transport properties (hole transport layer).

[0321] A configuration having a layer 4420, an emissive layer 4411, and a layer 4430 provided between a pair of electrodes can function as a single emissive unit, and in this specification, the configuration shown in Figure 27A is referred to as a single structure.

[0322] Furthermore, Figure 27B shows a modified example of the EL layer 172 of the light-emitting element 170 shown in Figure 27A. Specifically, the light-emitting element 170 shown in Figure 27B has a layer 4430-1 on the electrode 171, a layer 4430-2 on layer 4430-1, a light-emitting layer 4411 on layer 4430-2, a layer 4420-1 on the light-emitting layer 4411, a layer 4420-2 on layer 4420-1, and an electrode 173 on layer 4420-2. For example, when electrode 171 is the anode and electrode 173 is the cathode, layer 4430-1 functions as a hole injection layer, layer 4430-2 functions as a hole transport layer, layer 4420-1 functions as an electron transport layer, and layer 4420-2 functions as an electron injection layer. Alternatively, when electrode 171 is the cathode and electrode 173 is the anode, layer 4430-1 functions as an electron injection layer, layer 4430-2 functions as an electron transport layer, layer 4420-1 functions as a hole transport layer, and layer 4420-2 functions as a hole injection layer. This layer structure allows for efficient injection of carriers into the light-emitting layer 4411 and improves the efficiency of carrier recombination within the light-emitting layer 4411.

[0323] As shown in Figure 27C, a configuration in which multiple light-emitting layers (light-emitting layers 4411, 4412, and 4413) are provided between layer 4420 and layer 4430 is also an example of a single structure.

[0324] Furthermore, as shown in Figure 27D, a configuration in which multiple light-emitting units (EL layer 172a, EL layer 172b) are connected in series via an intermediate layer (charge generation layer) 4440 is referred to as a tandem structure or stack structure in this specification. It should be noted that a tandem structure enables the realization of a light-emitting element capable of high-brightness emission.

[0325] Furthermore, if the light-emitting element 170 is in a tandem structure as shown in Figure 27D, the light-emitting colors of the EL layer 172a and EL layer 172b may be the same. For example, the light-emitting colors of both EL layer 172a and EL layer 172b may be green. Note that if the display area 235 includes three sub-pixels R, G, and B, and each sub-pixel has a light-emitting element, the light-emitting elements of each sub-pixel may be in a tandem structure. Specifically, the EL layer 172a and EL layer 172b of the R sub-pixel each have a material capable of emitting red light, the EL layer 172a and EL layer 172b of the G sub-pixel each have a material capable of emitting green light, and the EL layer 172a and EL layer 172b of the B sub-pixel each have a material capable of emitting blue light. In other words, the materials of the light-emitting layer 4411 and the light-emitting layer 4412 may be the same. By making the light-emitting color of EL layer 172a and EL layer 172b the same, the current density per unit of luminous intensity can be reduced. Therefore, the reliability of the light-emitting element 170 can be improved.

[0326] The light-emitting color of the light-emitting element can be red, green, blue, cyan, magenta, yellow, or white, depending on the material that makes up the EL layer 172. Furthermore, the color purity can be further enhanced by adding a microcavity structure to the light-emitting element.

[0327] The light-emitting layer may contain two or more light-emitting materials that emit light such as R (red), G (green), B (blue), Y (yellow), and O (orange). For light-emitting devices that emit white light, it is preferable to have a configuration in which the light-emitting layer contains two or more types of light-emitting materials. To obtain white light emission, one should select light-emitting materials such that the light emitted by each of the two or more materials is complementary in color. For example, by making the light-emitting color of the first light-emitting layer and the light-emitting color of the second light-emitting layer complementary, a light-emitting device that emits white light as a whole can be obtained. The same applies to light-emitting devices having three or more light-emitting layers.

[0328] The light-emitting layer preferably contains two or more light-emitting materials that emit light such as R (red), G (green), B (blue), Y (yellow), and O (orange). Alternatively, it is preferable to have two or more light-emitting materials, and for each light-emitting material to emit light that contains spectral components of two or more colors from R, G, and B.

[0329] Examples of luminescent materials include fluorescent materials, phosphorescent materials, inorganic compounds (such as quantum dot materials), and thermally activated delayed fluorescence (TADF) materials. For TADF materials, materials in thermal equilibrium between the singlet and triplet excited states may also be used. Such TADF materials have a shorter emission lifetime (excitation lifetime), which helps suppress efficiency degradation in the high-brightness region of the light-emitting element.

[0330] This embodiment can be implemented in appropriate combination with the configurations described in other embodiments.

[0331] (Embodiment 4) This embodiment describes an example of a transistor structure that can be used in a display device according to one aspect of the present invention.

[0332] <Transistor Configuration Example 1> As an example of a transistor structure, transistor 70A will be explained using Figures 28A, 28B, and 28C. Figure 28A is a top view of transistor 70A. Figure 28B is a cross-sectional view of the area indicated by the dashed line X1-X2 in Figure 28A, and Figure 28C is a cross-sectional view of the area indicated by the dashed line Y1-Y2 in Figure 28A. For clarity, some components of transistor 70A (such as the insulating layer that functions as a gate insulating layer) are omitted in Figure 28A. The direction of extension of the dashed line X1-X2 is sometimes referred to as the channel length direction, and the direction of extension of the dashed line Y1-Y2 is sometimes referred to as the channel width direction.

[0333] The transistor 70A includes a conductive layer 521 on an insulating layer 524, an insulating layer 511 on the insulating layer 524 and the conductive layer 521, a semiconductor layer 531 on the insulating layer 511, a conductive layer 522a on the semiconductor layer 531 and the insulating layer 511, a conductive layer 522b on the semiconductor layer 531 and the insulating layer 511, an insulating layer 512 on the semiconductor layer 531, the conductive layer 522a, and the conductive layer 522b, and a conductive layer 523 on the insulating layer 512. The insulating layer 524 may be a substrate.

[0334] Furthermore, as the semiconductor layer 531, for example, the semiconductor material shown in the above embodiment can be used. For example, an oxide semiconductor, which is a type of metal oxide, may be used as the semiconductor layer 531.

[0335] The insulating layer 511 and the insulating layer 512 have openings 535. The conductive layer 523 is electrically connected to the conductive layer 521 through the openings 535.

[0336] Here, insulating layer 511 functions as the first gate insulating layer of transistor 70A, and insulating layer 512 functions as the second gate insulating layer of transistor 70A. In transistor 70A, conductive layer 521 functions as the first gate, conductive layer 522a functions as either the source or the drain, and conductive layer 522b functions as either the source or the drain. In transistor 70A, conductive layer 523 functions as the second gate.

[0337] The 70A transistor is a so-called channel-etch type transistor and has a dual-gate structure.

[0338] Furthermore, transistor 70A can also be configured without the conductive layer 523. In this case, transistor 70A is a so-called channel-etched transistor and has a bottom-gate structure.

[0339] As shown in Figures 28B and 28C, the semiconductor layer 531 is positioned opposite the conductive layers 521 and 523 and is sandwiched between the two conductive layers that function as gates. The length of the conductive layer 523 in the channel length direction and the length of the conductive layer 523 in the channel width direction are longer than the length of the semiconductor layer 531 in the channel length direction and the length of the semiconductor layer 531 in the channel width direction, respectively, and the entire semiconductor layer 531 is covered by the conductive layer 523 via the insulating layer 512.

[0340] In other words, the conductive layer 521 and the conductive layer 523 are connected at an opening 535 provided in the insulating layer 511 and the insulating layer 512, and have a region located outside the side edge of the semiconductor layer 531.

[0341] With this configuration, the semiconductor layer 531 included in the transistor 70A can be electrically surrounded by the electric fields of the conductive layers 521 and 523 to form an S-channel structure.

[0342] Because transistor 70A has an s-channel structure, the conductive layer 521, which functions as the first gate, can effectively apply an electric field to the semiconductor layer 531 to induce a channel. Therefore, the current driving capability of transistor 70A is improved, and high on-current characteristics can be obtained. In addition, because the on-current can be increased, miniaturization of transistor 70A becomes possible.

[0343] Furthermore, since transistor 70A has a structure in which the semiconductor layer 531 is surrounded by a conductive layer 521 that functions as a first gate and a conductive layer 523 that functions as a second gate, the mechanical strength of transistor 70A can be increased.

[0344] <Example of transistor configuration 2> As an example of transistor structure, transistor 70B will be explained using Figures 29A, 29B, and 29C. Figure 29A is a top view of transistor 70B. Figure 29B is a cross-sectional view of the region indicated by the dashed line X1-X2 in Figure 29A, and Figure 29C is a cross-sectional view of the region indicated by the dashed line Y1-Y2 in Figure 29A.

[0345] The transistor 70B shown in Figures 29A, 29B, and 29C has a conductive layer 521 on an insulating layer 524, an insulating layer 511 on the conductive layer 521 and on the insulating layer 524, a semiconductor layer 531 on the insulating layer 511, an insulating layer 512 on the semiconductor layer 531, a conductive layer 523 on the insulating layer 512, and an insulating layer 515 on the insulating layer 511, the semiconductor layer 531, and the conductive layer 523. The semiconductor layer 531 has a channel-forming region 531i that overlaps with the conductive layer 523, a source region 531s that is in contact with the insulating layer 515, and a drain region 531d that is in contact with the insulating layer 515. For example, an oxide semiconductor, which is a type of metal oxide, can be used as the semiconductor layer 531. The semiconductor layer 531 may be arranged in a stacked configuration of two or more layers.

[0346] Furthermore, the insulating layer 515 contains nitrogen or hydrogen. When the insulating layer 515 comes into contact with the source region 531s and the drain region 531d, nitrogen or hydrogen in the insulating layer 515 is added to the source region 531s and the drain region 531d. The carrier concentration in the source region 531s and the drain region 531d increases due to the addition of nitrogen or hydrogen.

[0347] Furthermore, transistor 70B may have a conductive layer 522a that is electrically connected to the source region 531s via an opening 536a provided in the insulating layer 515. Also, transistor 70B may have a conductive layer 522b that is electrically connected to the drain region 531d via an opening 536b provided in the insulating layer 515.

[0348] The insulating layer 511 functions as a first gate insulating layer, and the insulating layer 512 functions as a second gate insulating layer. In addition, the insulating layer 515 functions as a protective insulating layer.

[0349] Furthermore, the insulating layer 512 has an excess oxygen region. The presence of this excess oxygen region in the insulating layer 512 allows for the supply of excess oxygen to the channel formation region 531i of the semiconductor layer 531. Therefore, any oxygen deficiencies that may form in the channel formation region 531i can be compensated for by the excess oxygen, thus providing a highly reliable display device.

[0350] In addition, to supply excess oxygen to the semiconductor layer 531, excess oxygen may be supplied to the insulating layer 511 formed below the semiconductor layer 531. In this case, the excess oxygen contained in the insulating layer 511 may also be supplied to the source region 531s and drain region 531d of the semiconductor layer 531. When excess oxygen is supplied to the source region 531s and drain region 531d, the resistance of the source region 531s and drain region 531d may increase.

[0351] On the other hand, by configuring the insulating layer 512 formed above the semiconductor layer 531 to have excess oxygen, it becomes possible to selectively supply excess oxygen only to the channel formation region 531i. Alternatively, after supplying excess oxygen to the channel formation region 531i, the source region 531s, and the drain region 531d, selectively increasing the carrier concentration in the source region 531s and the drain region 531d can suppress an increase in the resistance of the source region 531s and the drain region 531d.

[0352] Furthermore, it is preferable that the source region 531s and drain region 531d of the semiconductor layer 531 each contain an element that forms an oxygen vacancy or an element that bonds with an oxygen vacancy. Typical examples of elements that form an oxygen vacancy or bond with an oxygen vacancy include hydrogen, boron, carbon, nitrogen, fluorine, phosphorus, sulfur, chlorine, titanium, and Group 18 elements. Typical examples of Group 18 elements include helium, neon, argon, krypton, and xenon. If one or more of the above-mentioned elements that form oxygen vacancies are contained in the insulating layer 515, they diffuse from the insulating layer 515 to the source region 531s and drain region 531d, and / or are added to the source region 531s and drain region 531d by impurity addition treatment.

[0353] When impurity elements are added to a metal oxide, the bond between the metal elements and oxygen in the metal oxide is broken, creating an oxygen vacancy. Alternatively, when impurity elements are added to a metal oxide, the oxygen that was bonded to the metal elements in the metal oxide bonds with the impurity elements, causing oxygen to be removed from the metal elements and creating an oxygen vacancy. As a result, the carrier concentration in the metal oxide increases, and its conductivity improves.

[0354] Furthermore, conductive layer 521 functions as a first gate, conductive layer 523 functions as a second gate, conductive layer 522a functions as a source, and conductive layer 522b functions as a drain.

[0355] Furthermore, as shown in Figure 29C, the insulating layer 511 and the insulating layer 512 are provided with openings 537. The conductive layer 521 is electrically connected to the conductive layer 523 via the openings 537. Therefore, the conductive layer 521 and the conductive layer 523 are given the same potential. Alternatively, the conductive layer 521 and the conductive layer 523 may be given different potentials without providing the openings 537. Or, the conductive layer 521 may be used as a light-shielding film without providing the openings 537. For example, by forming the conductive layer 521 from a light-shielding material, light from below irradiating the channel formation region 531i can be suppressed.

[0356] Furthermore, as shown in Figures 29B and 29C, the semiconductor layer 531 is positioned opposite the conductive layer 521, which functions as a first gate, and the conductive layer 523, which functions as a second gate, and is sandwiched between the two conductive layers that function as gates.

[0357] Furthermore, transistor 70B also adopts an S-channel structure, similar to transistor 70C. With this configuration, the semiconductor layer 531 contained in transistor 70B can be electrically surrounded by the electric fields of the conductive layer 521, which functions as a first gate, and the conductive layer 523, which functions as a second gate.

[0358] Because transistor 70B has an S-channel structure, the conductive layer 521 or 523 can effectively apply an electric field to the semiconductor layer 531 to induce a channel. This improves the current driving capability of transistor 70B and makes it possible to obtain high on-current characteristics. Furthermore, because it is possible to increase the on-current, it becomes possible to miniaturize transistor 70B. In addition, because transistor 70B has a structure in which the semiconductor layer 531 is surrounded by conductive layers 521 and 523, the mechanical strength of transistor 70B can be increased.

[0359] Furthermore, transistor 70B may also be referred to as a TGSA (Top Gate Self Align) type FET, based on the position of the conductive layer 523 relative to the semiconductor layer 531, or the method of forming the conductive layer 523.

[0360] Furthermore, in transistor 70B, the insulating layer 512 is provided only in the portion that overlaps with the conductive layer 523, but the configuration is not limited to this, and the insulating layer 512 can also cover the semiconductor layer 531. Alternatively, the conductive layer 521 can be omitted.

[0361] Alternatively, an aluminum oxide layer may be provided between the insulating layer 512 and the conductive layer 523. By providing an aluminum oxide layer, excess oxygen contained in the insulating layer 512 can be less likely to diffuse to the conductive layer 523.

[0362] Furthermore, it is preferable that the conductive layer 523 is made of a material that does not easily allow oxygen to diffuse, at least in the region that is in contact with the insulating layer 512. Examples of such materials include aluminum and molybdenum. For example, the conductive layer 523 may have a two-layer laminated structure in which aluminum is provided on the insulating layer 512 side and titanium is provided on top of that. Alternatively, the conductive layer 523 may have a three-layer laminated structure in which molybdenum is provided on the insulating layer 512 side and aluminum and titanium are provided on top of that.

[0363] <Transistor Configuration Example 3> As an example of transistor structure, transistor 70C will be explained using Figures 30A to 30C.

[0364] Figure 30A is a top view of transistor 70C. Figure 30B is a cross-sectional view of the region indicated by the dashed line X1-X2 in Figure 30A, and is also a cross-sectional view of transistor 70C in the channel length direction. Figure 30C is a cross-sectional view of the region indicated by the dashed line Y1-Y2 in Figure 30A, and is also a cross-sectional view of transistor 70C in the channel width direction. Note that in the top view of Figure 30A, some elements have been omitted for clarity.

[0365] As shown in Figure 30, the transistor 70C has a metal oxide 330a disposed on a substrate (not shown), a metal oxide 330b disposed on the metal oxide 330a, conductors 242a and 242b disposed on the metal oxide 330b at a distance from each other, an insulator 280 disposed on the conductors 242a and 242b with an opening formed between the conductors 242a and 242b, a conductor 260 disposed in the opening, an insulator 250 disposed between the metal oxide 330b, conductors 242a, conductors 242b, and insulator 280 and conductor 260, and a metal oxide 330c disposed between the metal oxide 330b, conductors 242a, conductors 242b, and insulator 280 and insulator 250. Here, as shown in Figures 30B and 30C, it is preferable that the upper surface of the conductor 260 substantially coincides with the upper surfaces of the insulators 250, 254, metal oxide 330c, and 280. In the following, metal oxides 330a, 330b, and 330c may be collectively referred to as metal oxide 330. Also, conductors 242a and 242b may be collectively referred to as conductor 242.

[0366] In the transistor 70C shown in Figure 30, the sides of the conductors 242a and 242b facing the conductor 260 have a generally vertical shape. However, the transistor 70C shown in Figure 30 is not limited to this, and the angle between the side and bottom surfaces of the conductors 242a and 242b may be 10° to 80°, preferably 30° to 60°. Furthermore, the opposing sides of the conductors 242a and 242b may have multiple surfaces.

[0367] As shown in Figure 30, it is preferable that an insulator 254 is placed between the insulator 224, metal oxide 330a, metal oxide 330b, conductor 242a, conductor 242b, and metal oxide 330c and the insulator 280. Here, it is preferable that the insulator 254 is in contact with the side surface of the metal oxide 330c, the top and side surfaces of the conductor 242a, the top and side surfaces of the conductor 242b, the side surfaces of the metal oxide 330a and metal oxide 330b, and the top surface of the insulator 224, as shown in Figures 30B and 30C.

[0368] In the transistor 70C, a configuration is shown in which three layers of metal oxide 330a, metal oxide 330b, and metal oxide 330c are stacked in the region where the channel is formed (hereinafter also referred to as the channel formation region) and in its vicinity. However, the present invention is not limited to this. For example, a two-layer structure of metal oxide 330b and metal oxide 330c, or a stacked structure of four or more layers, may be provided. Also, in the transistor 70C, the conductor 260 is shown as a two-layer stacked structure. However, the present invention is not limited to this. For example, the conductor 260 may be a single-layer structure or a stacked structure of three or more layers. Furthermore, each of the metal oxide 330a, metal oxide 330b, and metal oxide 330c may have a stacked structure of two or more layers.

[0369] For example, if the metal oxide 330c has a layered structure consisting of a first metal oxide and a second metal oxide on the first metal oxide, it is preferable that the first metal oxide has the same composition as metal oxide 330b and the second metal oxide has the same composition as metal oxide 330a.

[0370] Here, the conductor 260 functions as the gate electrode of the transistor, and the conductors 242a and 242b function as the source electrode or drain electrode, respectively. As described above, the conductor 260 is formed to be embedded in the opening of the insulator 280 and in the region sandwiched between the conductors 242a and 242b. Here, the arrangement of the conductors 260, 242a, and 242b is selected in a self-aligned manner with respect to the opening of the insulator 280. In other words, in transistor 70C, the gate electrode can be positioned in a self-aligned manner between the source electrode and the drain electrode. Therefore, since the conductor 260 can be formed without providing a positional margin, the occupied area of ​​transistor 70C can be reduced. This makes it possible to make the display device high-resolution. It also makes it possible to make the display device have a narrow bezel.

[0371] As shown in Figure 30, it is preferable that the conductor 260 has a conductor 260a provided inside the insulator 250 and a conductor 260b provided so as to be embedded inside the conductor 260a.

[0372] The transistor 70C preferably includes an insulator 214 disposed on a substrate (not shown), an insulator 216 disposed on top of the insulator 214, a conductor 205 disposed so as to be embedded in the insulator 216, an insulator 222 disposed on top of the insulator 216 and the conductor 205, and an insulator 224 disposed on top of the insulator 222. It is preferable that a metal oxide 330a is disposed on top of the insulator 224.

[0373] It is preferable that insulators 274 and 281, which function as interlayer films, are placed on top of the transistor 70C. Here, it is preferable that insulator 274 is placed in contact with the upper surfaces of the conductor 260, insulator 250, insulator 254, metal oxide 330c, and insulator 280.

[0374] It is preferable that insulators 222, 254, and 274 have a function to suppress the diffusion of at least one of the hydrogen (e.g., hydrogen atoms, hydrogen molecules, etc.). For example, it is preferable that insulators 222, 254, and 274 have lower hydrogen permeability than insulators 224, 250, and 280. It is also preferable that insulators 222 and 254 have a function to suppress the diffusion of at least one of the oxygen (e.g., oxygen atoms, oxygen molecules, etc.). For example, it is preferable that insulators 222 and 254 have lower oxygen permeability than insulators 224, 250, and 280.

[0375] Here, insulator 224, metal oxide 330, and insulator 250 are separated from insulators 280 and 281 by insulators 254 and 274. Therefore, it is possible to suppress the mixing of impurities such as hydrogen, or excess oxygen, contained in insulators 280 and 281, into insulators 224, metal oxide 330a, metal oxide 330b, and insulator 250.

[0376] It is preferable that a conductor 340 (conductor 340a and conductor 340b) is provided that is electrically connected to the transistor 70C and functions as a plug. In addition, an insulator 241 (insulator 241a and insulator 241b) is provided in contact with the side surface of the conductor 340 that functions as a plug. That is, the insulator 241 is provided in contact with the inner wall of the opening of the insulator 254, insulator 280, insulator 274, and insulator 281. Alternatively, a first conductor of the conductor 340 may be provided in contact with the side surface of the insulator 241, and a second conductor of the conductor 340 may be provided further inside. Here, the height of the upper surface of the conductor 340 and the height of the upper surface of the insulator 281 can be made to be approximately the same. Although the transistor 70C shows a configuration in which the first conductor and the second conductor of the conductor 340 are stacked, the present invention is not limited to this. For example, the conductor 340 may be provided as a single layer or as a laminated structure of three or more layers. When the structure has a laminated structure, an ordinal number may be assigned to distinguish it according to the order of formation.

[0377] In transistor 70C, it is preferable to use a metal oxide that functions as an oxide semiconductor (hereinafter also referred to as an oxide semiconductor) for the metal oxide 330 (metal oxide 330a, metal oxide 330b, and metal oxide 330c) that includes the channel formation region. For example, it is preferable to use a metal oxide with a band gap of 2 eV or more, preferably 2.5 eV or more, as the metal oxide that forms the channel formation region of the metal oxide 330.

[0378] The above metal oxide preferably contains at least indium (In) or zinc (Zn). In particular, it is preferable that it contains indium (In) and zinc (Zn). In addition, it is preferable that it contains element M. As element M, one or more of the following can be used: aluminum (Al), gallium (Ga), yttrium (Y), tin (Sn), boron (B), titanium (Ti), iron (Fe), nickel (Ni), germanium (Ge), zirconium (Zr), molybdenum (Mo), lanthanum (La), cerium (Ce), neodymium (Nd), hafnium (Hf), tantalum (Ta), tungsten (W), magnesium (Mg), or cobalt (Co). In particular, it is preferable that element M is one or more of aluminum (Al), gallium (Ga), yttrium (Y), or tin (Sn). Furthermore, it is even more preferable that element M contains either Ga or Sn, or both.

[0379] Furthermore, as shown in Figure 30B, the thickness of the metal oxide 330b in the region that does not overlap with the conductor 242 may be thinner than the thickness of the metal oxide 330b in the region that overlaps with the conductor 242. This is formed by removing a portion of the upper surface of the metal oxide 330b when forming the conductors 242a and 242b. When a conductive film that will become the conductor 242 is deposited on the upper surface of the metal oxide 330b, a region with low resistance may be formed near the interface with the conductive film. In this way, by removing the region with low resistance located between the conductors 242a and 242b on the upper surface of the metal oxide 330b, it is possible to prevent the formation of a channel in that region.

[0380] According to one aspect of the present invention, a display device with a small size transistor and high resolution can be provided. Alternatively, a display device with a large on-current transistor and high brightness can be provided. Alternatively, a display device with a fast-operating transistor and fast operation can be provided. Alternatively, a display device with a stable electrical characteristic transistor and high reliability can be provided. Alternatively, a display device with a small off-current transistor and low power consumption can be provided.

[0381] A detailed configuration of transistor 70C, which can be used in a display device according to one aspect of the present invention, will be described.

[0382] The conductor 205 is arranged so as to have an overlapping region with the metal oxide 330 and the conductor 260. Furthermore, it is preferable that the conductor 205 is embedded in the insulator 216.

[0383] The conductor 205 comprises conductor 205a, conductor 205b, and conductor 205c. Conductor 205a is provided in contact with the bottom surface and side wall of an opening provided in the insulator 216. Conductor 205b is provided so as to be embedded in a recess formed in conductor 205a. Here, the upper surface of conductor 205b is lower than the upper surface of conductor 205a and the upper surface of the insulator 216. Conductor 205c is provided in contact with the upper surface of conductor 205b and the side surface of conductor 205a. Here, the height of the upper surface of conductor 205c is approximately equal to the height of the upper surface of conductor 205a and the upper surface of the insulator 216. In other words, conductor 205b is enclosed by conductors 205a and 205c.

[0384] It is preferable to use conductive materials for conductors 205a and 205c that have the function of suppressing the diffusion of impurities such as hydrogen atoms, hydrogen molecules, water molecules, nitrogen atoms, nitrogen molecules, nitrogen oxide molecules (N2O, NO, NO2, etc.), and copper atoms. Alternatively, it is preferable to use conductive materials that have the function of suppressing the diffusion of oxygen (for example, at least one such as oxygen atoms or oxygen molecules).

[0385] By using conductive materials that have the function of reducing hydrogen diffusion for conductors 205a and 205c, it is possible to suppress the diffusion of impurities such as hydrogen contained in conductor 205b into the metal oxide 330 via the insulator 224, etc. Furthermore, by using conductive materials that have the function of suppressing oxygen diffusion for conductors 205a and 205c, it is possible to suppress the oxidation of conductor 205b and the resulting decrease in conductivity. As conductive materials that have the function of suppressing oxygen diffusion, it is preferable to use, for example, titanium, titanium nitride, tantalum, tantalum nitride, ruthenium, ruthenium oxide, etc. Therefore, the conductive material can be used as a single layer or in a laminate for conductor 205a. For example, titanium nitride can be used for conductor 205a.

[0386] Furthermore, it is preferable to use a conductive material whose main component is tungsten, copper, or aluminum for the conductor 205b. For example, tungsten may be used for the conductor 205b.

[0387] Here, conductor 260 may function as the first gate (also called the top gate) electrode. Also, conductor 205 may function as the second gate (also called the bottom gate) electrode. In that case, by changing the potential applied to conductor 205 independently of the potential applied to conductor 260, the V of transistor 70C can be controlled. th This can be controlled. In particular, by applying a negative potential to the conductor 205, the V of transistor 70C can be controlled. th By making the voltage greater than 0V, it becomes possible to reduce the off-current. Therefore, applying a negative potential to the conductor 205 reduces the drain current when the potential applied to the conductor 260 is 0V compared to not applying a negative potential.

[0388] The conductor 205 should be larger than the channel-forming region in the metal oxide 330. In particular, as shown in Figure 30C, it is preferable that the conductor 205 extends to the region outside the end that intersects with the channel width direction of the metal oxide 330. That is, it is preferable that the conductor 205 and the conductor 260 are superimposed on the outside of the side surface in the channel width direction of the metal oxide 330, with an insulator in between.

[0389] With the above configuration, the channel-forming region of the metal oxide 330 can be electrically surrounded by the electric field of the conductor 260, which functions as the first gate electrode, and the electric field of the conductor 205, which functions as the second gate electrode.

[0390] As shown in Figure 30C, the conductor 205 is extended to function as wiring. However, the configuration is not limited to this, and a conductor that functions as wiring may be provided beneath the conductor 205.

[0391] The insulator 214 preferably functions as a barrier insulating film that suppresses the ingress of impurities such as water or hydrogen from the substrate side into the transistor 70C. Therefore, it is preferable to use an insulating material for the insulator 214 that has the function of suppressing the diffusion of impurities such as hydrogen atoms, hydrogen molecules, water molecules, nitrogen atoms, nitrogen molecules, nitrogen oxide molecules (N2O, NO, NO2, etc.), and copper atoms (i.e., the above impurities are less permeable). Alternatively, it is preferable to use an insulating material that has the function of suppressing the diffusion of oxygen (for example, at least one such as oxygen atoms or oxygen molecules) (i.e., the above oxygen is less permeable).

[0392] For example, it is preferable to use aluminum oxide or silicon nitride as the insulator 214. This suppresses the diffusion of impurities such as water or hydrogen from the substrate side to the transistor 70C side beyond the insulator 214. Alternatively, it suppresses the diffusion of oxygen contained in the insulator 224, etc., to the substrate side beyond the insulator 214.

[0393] The insulators 216, 280, and 281, which function as interlayer films, preferably have a lower dielectric constant than insulator 214. By using a material with a low dielectric constant as the interlayer film, parasitic capacitance between wiring can be reduced. For example, silicon oxide, silicon oxynitride, silicon nitride, silicon nitride, silicon oxide with added fluorine, silicon oxide with added carbon, silicon oxide with added carbon and nitrogen, or porous silicon oxide may be used as insulators 216, 280, and 281.

[0394] Insulators 222 and 224 function as gate insulators.

[0395] Here, it is preferable that the insulator 224 in contact with the metal oxide 330 deoxygenates upon heating. In this specification, oxygen that is deoxygenated upon heating is sometimes referred to as excess oxygen. For example, the insulator 224 may be silicon oxide or silicon oxynitride, etc., as appropriate. By providing an oxygen-containing insulator in contact with the metal oxide 330, oxygen deficiency in the metal oxide 330 can be reduced, and the reliability of the transistor 70C can be improved.

[0396] Specifically, it is preferable to use an oxide material in which some oxygen is desorbed upon heating as the insulator 224. An oxide that desorbs oxygen upon heating is one in which the amount of oxygen desorbed, converted to oxygen atoms, is 1.0 × 10¹⁶ as determined by TDS (Thermal Desorption Spectroscopy) analysis. 18 atoms / cm 3 Preferably 1.0 × 10 19 atoms / cm 3 More preferably 2.0 × 10 19 atoms / cm 3 The above, or 3.0 × 10 20 atoms / cm 3 The oxide film is as described above. The surface temperature of the film during the TDS analysis is preferably in the range of 100°C to 700°C, or 100°C to 400°C.

[0397] As shown in Figure 30C, the thickness of the insulator 224 in the region that does not overlap with the insulator 254 and does not overlap with the metal oxide 330b may be thinner than the thickness of the other regions. In the insulator 224, it is preferable that the thickness of the region that does not overlap with the insulator 254 and does not overlap with the metal oxide 330b is such that the above-mentioned oxygen can diffuse sufficiently.

[0398] The insulator 222, like the insulator 214, preferably functions as a barrier insulating film that suppresses the ingress of impurities such as water or hydrogen into the transistor 70C from the substrate side. For example, it is preferable that the insulator 222 has lower hydrogen permeability than the insulator 224. By surrounding the insulator 224, the metal oxide 330, and the insulator 250, etc., with the insulators 222, 254, and 274, it is possible to suppress the ingress of impurities such as water or hydrogen into the transistor 70C from the outside.

[0399] Furthermore, it is preferable that the insulator 222 has a function to suppress the diffusion of oxygen (for example, at least one such as an oxygen atom or oxygen molecule) (i.e., it is difficult for the above-mentioned oxygen to permeate it). For example, it is preferable that the insulator 222 has lower oxygen permeability than the insulator 224. It is preferable that the insulator 222 has a function to suppress the diffusion of oxygen or impurities, thereby reducing the diffusion of oxygen contained in the metal oxide 330 to the substrate side. In addition, it is possible to suppress the reaction of the conductor 205 with the oxygen contained in the insulator 224 or the oxygen contained in the metal oxide 330.

[0400] The insulator 222 may be an insulator containing an oxide of either or both aluminum and hafnium, which are insulating materials. Preferably, the insulator containing an oxide of either or both aluminum and hafnium is an aluminum oxide, hafnium oxide, or an oxide containing aluminum and hafnium (hafnium aluminate). When the insulator 222 is formed using such a material, the insulator 222 functions as a layer that suppresses the release of oxygen from the metal oxide 330 and the incorporation of impurities such as hydrogen from the periphery of the transistor 70C into the metal oxide 330.

[0401] Alternatively, aluminum oxide, bismuth oxide, germanium oxide, niobium oxide, silicon oxide, titanium oxide, tungsten oxide, yttrium oxide, or zirconium oxide may be added to these insulators. Alternatively, these insulators may be subjected to nitriding treatment. Silicon oxide, silicon oxide nitride, or silicon nitride may be laminated onto the above insulators.

[0402] The insulator 222 may be a single-layer or multi-layer insulator containing so-called high-k materials such as aluminum oxide, hafnium oxide, tantalum oxide, zirconium oxide, lead zirconate titanate (PZT), strontium titanate (SrTiO3), or (Ba,Sr)TiO3 (BST). As transistors become smaller and more integrated, thinning of the gate insulator can lead to problems such as leakage current. By using a high-k material as the insulator that functions as the gate insulator, it becomes possible to reduce the gate potential during transistor operation while maintaining the physical film thickness.

[0403] Furthermore, the insulators 222 and 224 may have a laminated structure of two or more layers. In that case, the laminated structure is not limited to being made of the same material, but may be made of different materials. For example, an insulator similar to the insulator 224 may be provided below the insulator 222.

[0404] The metal oxide 330 comprises a metal oxide 330a, a metal oxide 330b on the metal oxide 330a, and a metal oxide 330c on the metal oxide 330b. By having the metal oxide 330a below the metal oxide 330b, the diffusion of impurities from structures formed below the metal oxide 330a to the metal oxide 330b can be suppressed. Furthermore, by having the metal oxide 330c on the metal oxide 330b, the diffusion of impurities from structures formed above the metal oxide 330c to the metal oxide 330b can be suppressed.

[0405] Furthermore, it is preferable that the metal oxide 330 has a layered structure of multiple oxide layers with different atomic ratios of each metal atom. For example, if the metal oxide 330 contains at least indium (In) and element M, it is preferable that the ratio of the number of atoms of element M contained in metal oxide 330a to the total number of atoms of all elements constituting metal oxide 330a is higher than the ratio of the number of atoms of element M contained in metal oxide 330b to the total number of atoms of all elements constituting metal oxide 330b. It is also preferable that the atomic ratio of element M contained in metal oxide 330a to In is higher than the atomic ratio of element M contained in metal oxide 330b to In. Here, metal oxide 330c can be any metal oxide that can be used in metal oxide 330a or metal oxide 330b.

[0406] It is preferable that the energy at the lower end of the conduction band of metal oxide 330a and metal oxide 330c is higher than the energy at the lower end of the conduction band of metal oxide 330b. In other words, it is preferable that the electron affinity of metal oxide 330a and metal oxide 330c is smaller than the electron affinity of metal oxide 330b. In this case, it is preferable that metal oxide 330c is a metal oxide that can be used for metal oxide 330a. Specifically, it is preferable that the ratio of the number of atoms of element M contained in metal oxide 330c to the total number of atoms of all elements constituting metal oxide 330c is higher than the ratio of the number of atoms of element M contained in metal oxide 330b to the total number of atoms of all elements constituting metal oxide 330b. It is also preferable that the atomic ratio of element M contained in metal oxide 330c to In is higher than the atomic ratio of element M contained in metal oxide 330b to In.

[0407] Here, at the junctions of metal oxide 330a, metal oxide 330b, and metal oxide 330c, the energy level at the lower end of the conduction band changes smoothly. In other words, the energy level at the lower end of the conduction band at the junctions of metal oxide 330a, metal oxide 330b, and metal oxide 330c can be said to change continuously or be continuously joined. To achieve this, it is desirable to lower the defect level density of the mixed layer formed at the interface between metal oxide 330a and metal oxide 330b, and at the interface between metal oxide 330b and metal oxide 330c.

[0408] Specifically, a mixed layer with a low defect level density can be formed by having metal oxide 330a and metal oxide 330b, and metal oxide 330b and metal oxide 330c, all having a common element other than oxygen (which serves as the main component). For example, if metal oxide 330b is In-Ga-Zn oxide, then In-Ga-Zn oxide, Ga-Zn oxide, gallium oxide, etc., may be used as metal oxide 330a and metal oxide 330c. Furthermore, metal oxide 330c may be in a layered structure. For example, a layered structure of In-Ga-Zn oxide and Ga-Zn oxide on the In-Ga-Zn oxide, or a layered structure of In-Ga-Zn oxide and gallium oxide on the In-Ga-Zn oxide can be used. In other words, a layered structure of In-Ga-Zn oxide and an oxide that does not contain In may be used as metal oxide 330c.

[0409] Specifically, for metal oxide 330a, a metal oxide with an atomic ratio of In:Ga:Zn = 1:3:4 or 1:1:0.5 may be used. For metal oxide 330b, a metal oxide with an atomic ratio of In:Ga:Zn = 4:2:3 or 3:1:2 may be used. For metal oxide 330c, a metal oxide with an atomic ratio of In:Ga:Zn = 1:3:4, In:Ga:Zn = 4:2:3, Ga:Zn = 2:1, or Ga:Zn = 2:5 may be used. Furthermore, specific examples of layered structures for metal oxide 330c include a layered structure of In:Ga:Zn=4:2:3 [atomic ratio] and Ga:Zn=2:1 [atomic ratio], a layered structure of In:Ga:Zn=4:2:3 [atomic ratio] and Ga:Zn=2:5 [atomic ratio], and a layered structure of In:Ga:Zn=4:2:3 [atomic ratio] and gallium oxide.

[0410] In this case, the main carrier pathway is through metal oxide 330b. By configuring metal oxide 330a and metal oxide 330c as described above, the defect level density at the interface between metal oxide 330a and metal oxide 330b, and at the interface between metal oxide 330b and metal oxide 330c, can be reduced. As a result, the influence of interface scattering on carrier conduction is reduced, and transistor 70C can obtain high on-current and high frequency characteristics. Furthermore, if metal oxide 330c is in a multilayer structure, in addition to the effect of reducing the defect level density at the interface between metal oxide 330b and metal oxide 330c as described above, it is expected that the constituent elements of metal oxide 330c will be suppressed from diffusing towards the insulator 250. More specifically, by making metal oxide 330c in a multilayer structure and positioning an oxide that does not contain In on top of the multilayer structure, it is possible to suppress In that could diffuse towards the insulator 250. Since the insulator 250 functions as a gate insulator, if In diffuses, it will result in poor transistor characteristics. Therefore, by using a layered structure for the metal oxide 330c, it becomes possible to provide a highly reliable display device.

[0411] A conductor 242 (conductor 242a and conductor 242b) that functions as a source electrode and a drain electrode is provided on the metal oxide 330b. It is preferable to use a metal element selected from aluminum, chromium, copper, silver, gold, platinum, tantalum, nickel, titanium, molybdenum, tungsten, hafnium, vanadium, niobium, manganese, magnesium, zirconium, beryllium, indium, ruthenium, iridium, strontium, and lanthanum as the conductor 242, or an alloy containing the above metal elements, or an alloy combining the above metal elements. For example, it is preferable to use tantalum nitride, titanium nitride, tungsten, nitrides containing titanium and aluminum, nitrides containing tantalum and aluminum, ruthenium oxide, ruthenium nitride, oxides containing strontium and ruthenium, oxides containing lanthanum and nickel, etc. Furthermore, tantalum nitride, titanium nitride, nitrides containing titanium and aluminum, nitrides containing tantalum and aluminum, ruthenium oxide, ruthenium nitride, oxides containing strontium and ruthenium, and oxides containing lanthanum and nickel are preferred because they are conductive materials that are resistant to oxidation or maintain conductivity even when absorbing oxygen.

[0412] By providing the conductor 242 in contact with the metal oxide 330, the oxygen concentration in the vicinity of the conductor 242 in the metal oxide 330 may be reduced. Furthermore, a metal compound layer containing the metal in the conductor 242 and components of the metal oxide 330 may be formed in the vicinity of the conductor 242 in the metal oxide 330. In such cases, the carrier concentration increases in the region of the metal oxide 330 near the conductor 242, resulting in a low-resistance region.

[0413] Here, the region between the conductor 242a and the conductor 242b is formed by superimposing it on the opening of the insulator 280. This allows the conductor 260 to be positioned self-aligned between the conductor 242a and the conductor 242b.

[0414] The insulator 250 functions as a gate insulator. It is preferable that the insulator 250 be placed in contact with the upper surface of the metal oxide 330c. The insulator 250 can be silicon oxide, silicon oxynitride, silicon nitride, silicon nitride, fluorine-added silicon oxide, carbon-added silicon oxide, carbon and nitrogen-added silicon oxide, or porous silicon oxide. Silicon oxide and silicon oxynitride are particularly preferred because they are thermally stable.

[0415] Similar to the insulator 224, it is preferable that the concentration of impurities such as water or hydrogen in the insulator 250 is reduced. The film thickness of the insulator 250 is preferably 1 nm or more and 20 nm or less.

[0416] A metal oxide may be provided between the insulator 250 and the conductor 260. It is preferable that the metal oxide suppresses oxygen diffusion from the insulator 250 to the conductor 260. This suppresses the oxidation of the conductor 260 by oxygen from the insulator 250.

[0417] The metal oxide may function as part of the gate insulator. Therefore, when silicon oxide or silicon oxynitride is used for the insulator 250, it is preferable to use a metal oxide that is a high-k material with a high dielectric constant. By making the gate insulator a laminated structure of insulator 250 and the metal oxide, a laminated structure that is stable against heat and has a high dielectric constant can be made. Therefore, it becomes possible to reduce the gate potential applied during transistor operation while maintaining the physical film thickness of the gate insulator. In addition, it becomes possible to thin the equivalent oxide film thickness (EOT) of the insulator that functions as a gate insulator.

[0418] Specifically, metal oxides containing one or more selected from hafnium, aluminum, gallium, yttrium, zirconium, tungsten, titanium, tantalum, nickel, germanium, or magnesium can be used. In particular, it is preferable to use insulators containing oxides of aluminum, hafnium, or both, such as aluminum oxide, hafnium oxide, or an oxide containing aluminum and hafnium (hafnium aluminate).

[0419] Although the conductor 260 is shown as a two-layer structure in Figure 30, it may also be a single-layer structure or a laminated structure of three or more layers.

[0420] It is preferable to use a conductor 260a that has the function of suppressing the diffusion of impurities such as hydrogen atoms, hydrogen molecules, water molecules, nitrogen atoms, nitrogen molecules, nitrogen oxide molecules (N2O, NO, NO2, etc.), and copper atoms. Alternatively, it is preferable to use a conductive material that has the function of suppressing the diffusion of oxygen (for example, at least one such as oxygen atoms or oxygen molecules).

[0421] The conductor 260a has the function of suppressing oxygen diffusion, thereby preventing the conductor 260b from oxidizing due to oxygen contained in the insulator 250 and reducing its conductivity. It is preferable to use a conductive material that has the function of suppressing oxygen diffusion, such as tantalum, tantalum nitride, ruthenium, or ruthenium oxide.

[0422] The conductor 260b is preferably made of a conductive material mainly composed of tungsten, copper, or aluminum. Furthermore, since the conductor 260 also functions as wiring, it is preferable to use a conductor with high conductivity. For example, a conductive material mainly composed of tungsten, copper, or aluminum can be used. The conductor 260b may also have a laminated structure, for example, a laminated structure of titanium or titanium nitride and the above conductive material.

[0423] As shown in Figures 30A and 30C, in the region of the metal oxide 330b that does not overlap with the conductor 242, in other words, in the channel-forming region of the metal oxide 330, the side surface of the metal oxide 330 is covered by the conductor 260. This makes it easier to apply the electric field of the conductor 260, which functions as the first gate electrode, to the side surface of the metal oxide 330. Therefore, the on-current of the transistor 70C can be increased and the frequency characteristics can be improved.

[0424] The insulator 254, like the insulator 214, preferably functions as a barrier insulating film that suppresses the ingress of impurities such as water or hydrogen into the transistor 70C from the insulator 280 side. For example, it is preferable that the insulator 254 has lower hydrogen permeability than the insulator 224. Furthermore, as shown in Figures 30B and 30C, it is preferable that the insulator 254 is in contact with the side surface of the metal oxide 330c, the top and side surfaces of the conductor 242a, the top and side surfaces of the conductor 242b, the side surfaces of the metal oxide 330a and metal oxide 330b, and the top surface of the insulator 224. With this configuration, it is possible to suppress the ingress of hydrogen contained in the insulator 280 into the metal oxide 330 from the top or side surfaces of the conductor 242a, conductor 242b, metal oxide 330a, metal oxide 330b, and the insulator 224.

[0425] Furthermore, it is preferable that the insulator 254 has the function of suppressing the diffusion of oxygen (for example, at least one such as an oxygen atom or oxygen molecule) (i.e., it is difficult for the above-mentioned oxygen to permeate through it). For example, it is preferable that the insulator 254 has lower oxygen permeability than the insulator 280 or the insulator 224.

[0426] The insulator 254 is preferably deposited using a sputtering method. By depositing the insulator 254 using a sputtering method in an oxygen-containing atmosphere, oxygen can be added to the vicinity of the region of the insulator 224 that is in contact with the insulator 254. This allows oxygen to be supplied from this region to the metal oxide 330 via the insulator 224. Here, the insulator 254 has a function to suppress upward diffusion of oxygen, thereby preventing oxygen from diffusing from the metal oxide 330 to the insulator 280. In addition, the insulator 222 has a function to suppress downward diffusion of oxygen, thereby preventing oxygen from diffusing from the metal oxide 330 to the substrate side. In this way, oxygen is supplied to the channel formation region of the metal oxide 330. This reduces oxygen deficiency in the metal oxide 330 and suppresses normally-on formation of the transistor.

[0427] As the insulator 254, for example, an insulator containing an oxide of one or both of aluminum and hafnium may be formed as a film. It is preferable to use aluminum oxide, hafnium oxide, or an oxide containing aluminum and hafnium (hafnium aluminate) as the insulator containing an oxide of one or both of aluminum and hafnium.

[0428] The insulator 224, insulator 250, and metal oxide 330 are covered by the hydrogen barrier insulator 254, and the insulator 280 is separated from the insulator 224, metal oxide 330, and insulator 250 by the insulator 254. This prevents impurities such as hydrogen from entering from the outside of the transistor 70C, thereby providing the transistor 70C with good electrical characteristics and reliability.

[0429] The insulator 280 is provided on the insulator 224, the metal oxide 330, and the conductor 242 via the insulator 254. For example, the insulator 280 is preferably silicon oxide, silicon oxynitride, silicon nitride, fluorine-added silicon oxide, carbon-added silicon oxide, carbon and nitrogen-added silicon oxide, or porous silicon oxide. Silicon oxide and silicon oxynitride are particularly preferred because they are thermally stable. Materials such as silicon oxide, silicon oxynitride, and porous silicon oxide are particularly preferred because they can easily form regions containing oxygen that is desorbed by heating.

[0430] It is preferable that the concentration of impurities such as water or hydrogen in the insulator 280 is reduced. Furthermore, the upper surface of the insulator 280 may be flattened.

[0431] The insulator 274 preferably functions as a barrier insulating film that suppresses the incorporation of impurities such as water or hydrogen into the insulator 280 from above, similar to the insulator 214. For example, the insulator 274 can be an insulator that can be used for the insulator 214, insulator 254, etc.

[0432] It is preferable to provide an insulator 281, which functions as an interlayer film, on top of the insulator 274. It is preferable that the insulator 281, like the insulator 224, has a reduced concentration of impurities such as water or hydrogen in the film.

[0433] Conductors 340a and 340b are placed in the openings formed in insulators 281, 274, 280, and 254. Conductors 340a and 340b are provided facing each other with conductor 260 in between. The height of the upper surfaces of conductors 340a and 340b may be on the same plane as the upper surface of insulator 281.

[0434] Furthermore, an insulator 241a is provided in contact with the inner wall of the opening of insulators 281, 274, 280, and 254, and a first conductive portion of conductor 340a is formed in contact with its side surface. Conductor 242a is located in at least a portion of the bottom of the opening, and conductor 340a is in contact with conductor 242a. Similarly, an insulator 241b is provided in contact with the inner wall of the opening of insulators 281, 274, 280, and 254, and a first conductive portion of conductor 340b is formed in contact with its side surface. Conductor 242b is located in at least a portion of the bottom of the opening, and conductor 340b is in contact with conductor 242b.

[0435] It is preferable that the conductors 340a and 340b are made of conductive materials mainly composed of tungsten, copper, or aluminum. Furthermore, the conductors 340a and 340b may be arranged in a laminated structure.

[0436] When the conductor 340 has a laminated structure, it is preferable to use a conductor that has the function of suppressing the diffusion of impurities such as water or hydrogen, as described above, for the conductors that come into contact with the metal oxide 330a, metal oxide 330b, conductor 242, insulator 254, insulator 280, insulator 274, and insulator 281. For example, it is preferable to use tantalum, tantalum nitride, titanium, titanium nitride, ruthenium, or ruthenium oxide. Furthermore, the conductive material that has the function of suppressing the diffusion of impurities such as water or hydrogen may be used in a single layer or a laminate. By using such a conductive material, it is possible to suppress the absorption of oxygen added to the insulator 280 by the conductors 340a and 340b. In addition, it is possible to suppress the mixing of impurities such as water or hydrogen from the layer above the insulator 281 into the metal oxide 330 through the conductors 340a and 340b.

[0437] For insulators 241a and 241b, any insulator that can be used for insulator 254, for example, may be used. Since insulators 241a and 241b are provided in contact with insulator 254, it is possible to suppress the mixing of impurities such as water or hydrogen from insulator 280, etc., into the metal oxide 330 through conductors 340a and 340b. Furthermore, it is possible to suppress the absorption of oxygen contained in insulator 280 into conductors 340a and 340b.

[0438] Although not shown in the figures, conductors that function as wiring may be placed in contact with the upper surfaces of conductor 340a and conductor 340b. It is preferable that the conductors functioning as wiring are made of a conductive material mainly composed of tungsten, copper, or aluminum. Furthermore, the conductors may have a laminated structure; for example, they may be laminates of titanium or titanium nitride and the conductive material. The conductors may also be formed to be embedded in openings provided in the insulator.

[0439] This embodiment can be implemented in appropriate combination with the configurations described in other embodiments.

[0440] (Embodiment 5) In this embodiment, an electronic device according to one aspect of the present invention will be described with reference to Figures 31 to 33.

[0441] The electronic device of this embodiment has a display device according to one aspect of the present invention in its display unit. The display device according to one aspect of the present invention can be used in the display units of various electronic devices.

[0442] Examples of electronic devices include television sets, desktop or notebook personal computers, computer monitors, digital signage, and large game machines such as pachinko machines, as well as other electronic devices with relatively large screens, digital cameras, digital video cameras, digital photo frames, mobile phones, portable game consoles, personal digital assistants, and audio playback devices.

[0443] In particular, since the display device according to one aspect of the present invention can increase resolution, it can be suitably used in electronic devices having a relatively small display area. Examples of such electronic devices include wristwatch-type and bracelet-type information terminals (wearable devices), as well as wearable devices that can be worn on the head, such as head-mounted displays for VR (Virtual Reality), glasses-type devices for AR (Augmented Reality), and devices for MR (Mixed Reality).

[0444] A display device according to one aspect of the present invention preferably has an extremely high resolution such as HD (1280 x 720 pixels), FHD (1920 x 1080 pixels), WQHD (2560 x 1440 pixels), WQXGA (2560 x 1600 pixels), 4K (3840 x 2160 pixels), or 8K (7680 x 4320 pixels). In particular, a resolution of 4K, 8K, or higher is preferred. Furthermore, the pixel density (resolution) of the display device according to one aspect of the present invention is preferably 100 ppi or more, preferably 300 ppi or more, more preferably 500 ppi or more, more preferably 1000 ppi or more, more preferably 2000 ppi or more, more preferably 3000 ppi or more, more preferably 5000 ppi or more, and even more preferably 7000 ppi or more. By using a display device that has either high resolution or high detail, or both, it becomes possible to further enhance the sense of presence and depth in personal electronic devices such as portable or home-use devices. Furthermore, there are no particular limitations on the screen ratio (aspect ratio) of the display device according to one embodiment of the present invention. For example, the display device can support various screen ratios such as 1:1 (square), 4:3, 16:9, and 16:10.

[0445] The electronic device of this embodiment may have sensors (including those with the function of measuring force, displacement, position, velocity, acceleration, angular velocity, rotational speed, distance, light, liquid, magnetism, temperature, chemical substances, sound, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, gradient, vibration, odor, or infrared radiation).

[0446] The electronic device of this embodiment can have a variety of functions. For example, it can have a function to display various information (still images, videos, text images, etc.) on the display unit, a touch panel function, a function to display a calendar, date or time, a function to execute various software (programs), a wireless communication function, a function to read programs or data recorded on a recording medium, and so on.

[0447] The electronic device 6500 shown in Figure 31A is a portable information terminal that can be used as a smartphone.

[0448] The electronic device 6500 includes a housing 6501, a display unit 6502, a power button 6503, a button 6504, a speaker 6505, a microphone 6506, a camera 6507, and a light source 6508, etc. The display unit 6502 has a touch panel function.

[0449] A display device according to one aspect of the present invention can be applied to the display unit 6502.

[0450] Figure 31B is a schematic cross-sectional view of the housing 6501, including the end on the microphone 6506 side.

[0451] A light-transmitting protective member 6510 is provided on the display side of the housing 6501, and the display panel 6511, optical member 6512, touch sensor panel 6513, printed circuit board 6517, battery 6518, etc. are arranged in the space enclosed by the housing 6501 and the protective member 6510.

[0452] The protective member 6510 is fixed to the display panel 6511, the optical member 6512, and the touch sensor panel 6513 by an adhesive layer (not shown).

[0453] In the area outside the display unit 6502, a portion of the display panel 6511 is folded back, and the FPC 6515 is connected to this folded portion. IC 6516 is mounted on the FPC 6515. The FPC 6515 is connected to terminals provided on the printed circuit board 6517.

[0454] A flexible display according to one embodiment of the present invention can be applied to the display panel 6511. This makes it possible to realize an extremely lightweight electronic device. Furthermore, because the display panel 6511 is extremely thin, it is possible to incorporate a large-capacity battery 6518 while keeping the thickness of the electronic device low. In addition, by folding back a part of the display panel 6511 and placing the connection part with the FPC 6515 on the back of the pixel area, it is possible to realize an electronic device with a narrow bezel.

[0455] Figure 32A shows an example of a television system. The television system 7100 has a display unit 7000 incorporated into a housing 7101. Here, the housing 7101 is shown supported by a stand 7103.

[0456] A display device according to one embodiment of the present invention can be applied to the display unit 7000.

[0457] The television device 7100 shown in Figure 32A can be operated using the operation switches on the housing 7101 and a separate remote control unit 7111. Alternatively, the display unit 7000 may be equipped with a touch sensor, and the television device 7100 can be operated by touching the display unit 7000 with a finger or the like. The remote control unit 7111 may have a display unit that displays information output from the remote control unit 7111. Channels and volume can be controlled and the image displayed on the display unit 7000 can be controlled using the operation keys or touch panel on the remote control unit 7111.

[0458] The television system 7100 is configured to include a receiver and a modem. The receiver can receive general television broadcasts. Furthermore, by connecting to a wired or wireless communication network via the modem, it is possible to perform one-way (from sender to receiver) or two-way (between sender and receiver, or between receivers, etc.) information communication.

[0459] Figure 32B shows an example of a notebook personal computer. The notebook personal computer 7200 has a casing 7211, a keyboard 7212, a pointing device 7213, an external connection port 7214, etc. A display unit 7000 is incorporated into the casing 7211.

[0460] A display device according to one aspect of the present invention can be applied to the display unit 7000.

[0461] Figures 32C and 32D show examples of digital signage.

[0462] The digital signage 7300 shown in Figure 32C includes a housing 7301, a display unit 7000, and a speaker 7303, etc. Furthermore, it may include LED lamps, operation keys (including a power switch or operation switch), connection terminals, various sensors, a microphone, etc.

[0463] Figure 32D shows a digital signage 7400 mounted on a cylindrical column 7401. The digital signage 7400 has a display unit 7000 that is provided along the curved surface of the column 7401.

[0464] In Figures 32C and 32D, a display device according to one embodiment of the present invention can be applied to the display unit 7000.

[0465] The larger the display area 7000, the more information can be provided at once. Furthermore, a larger display area 7000 is more eye-catching, which can, for example, enhance the effectiveness of advertising.

[0466] Applying a touch panel to the display unit 7000 is preferable because it not only allows images or videos to be displayed on the display unit 7000, but also enables intuitive operation by the user. Furthermore, when used for purposes such as providing route information or traffic information, intuitive operation can enhance usability.

[0467] Furthermore, as shown in Figures 32C and 32D, it is preferable that the digital signage 7300 or digital signage 7400 can be linked wirelessly with an information terminal 7311 or information terminal 7411 such as a smartphone owned by the user. For example, the advertising information displayed on the display unit 7000 can be displayed on the screen of the information terminal 7311 or information terminal 7411. Also, the display on the display unit 7000 can be switched by operating the information terminal 7311 or information terminal 7411.

[0468] Furthermore, the digital signage 7300 or digital signage 7400 can be used to run games using the screen of the information terminal 7311 or information terminal 7411 as the control device (controller). This allows an unspecified number of users to participate in and enjoy the game simultaneously.

[0469] The electronic equipment shown in Figures 33A to 33F includes a housing 9000, a display unit 9001, a speaker 9003, operation keys 9005 (including a power switch or operation switch), connection terminals 9006, sensors 9007 (including functions for measuring force, displacement, position, velocity, acceleration, angular velocity, rotational speed, distance, light, liquid, magnetism, temperature, chemical substances, sound, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, gradient, vibration, odor, or infrared radiation), a microphone 9008, etc.

[0470] The electronic devices shown in Figures 33A to 33F have various functions. For example, they may have functions to display various information (still images, videos, text images, etc.) on a display unit, a touch panel function, a function to display a calendar, date or time, a function to control processing by various software (programs), a wireless communication function, a function to read and process programs or data recorded on a recording medium, etc. However, the functions of electronic devices are not limited to these and can have various functions. Electronic devices may have multiple display units. Furthermore, electronic devices may be equipped with a camera, etc., and have functions to capture still images or videos and save them to a recording medium (external or built into the camera), a function to display the captured images on a display unit, etc.

[0471] Details of the electronic equipment shown in Figures 33A to 33F will be explained below.

[0472] Figure 33A is a perspective view showing a personal digital assistant (PDA) 9101. The PDA 9101 can be used, for example, as a smartphone. The PDA 9101 may also be equipped with a speaker 9003, connection terminals 9006, sensors 9007, etc. The PDA 9101 can also display text and image information on multiple surfaces. Figure 33A shows an example where three icons 9050 are displayed. Information 9051, indicated by a dashed rectangle, can also be displayed on other surfaces of the display unit 9001. Examples of information 9051 include notifications of incoming emails, SNS messages, phone calls, etc., the subject of an email or SNS message, the sender's name, date and time, time, battery level, signal strength, etc. Alternatively, icons 9050 or the like may be displayed in the position where the information 9051 is displayed.

[0473] Figure 33B is a perspective view showing the personal digital assistant (PDA) 9102. The PDA 9102 has the function of displaying information on three or more sides of the display unit 9001. Here, an example is shown in which information 9052, information 9053, and information 9054 are displayed on different sides. For example, a user can check information 9053, which is displayed in a position that can be observed from above the PDA 9102, while the PDA 9102 is stored in the breast pocket of their clothing. The user can check the display without taking the PDA 9102 out of their pocket and decide, for example, whether or not to answer a call.

[0474] Figure 33C is a perspective view showing a wristwatch-type personal information terminal 9200. The personal information terminal 9200 can be used, for example, as a smartwatch (registered trademark). The display unit 9001 has a curved display surface, allowing it to display information along the curved surface. The personal information terminal 9200 can also make hands-free calls by communicating with, for example, a wireless communication headset. Furthermore, the personal information terminal 9200 can transmit data to other information terminals and be charged via a connection terminal 9006. Charging may be performed by wireless power supply.

[0475] Figures 33D to 33F are perspective views showing a foldable personal information terminal 9201. Figure 33D shows the personal information terminal 9201 in an unfolded state, Figure 33F shows it in a folded state, and Figure 33E shows a perspective view of the transition between Figures 33D and 33F. The personal information terminal 9201 offers excellent portability in its folded state and excellent readability of the display due to its seamless, wide display area in its unfolded state. The display unit 9001 of the personal information terminal 9201 is supported by three housings 9000 connected by a hinge 9055. For example, the display unit 9001 can be bent with a radius of curvature of 0.1 mm to 150 mm.

[0476] This embodiment can be implemented in appropriate combination with the configurations described in other embodiments. [Explanation of Symbols]

[0477] 100: Display device, 111: Substrate, 112: Insulating layer, 113: Insulating layer, 114: Insulating layer, 115: Insulating layer, 116: Insulating layer, 118: Conductive layer, 121: Substrate, 122: Insulating layer, 124: FPC, 125: Wiring, 126: Protective layer

Claims

1. A method for manufacturing a display device including first to third light-emitting elements, A first manufacturing step for forming the first light-emitting element, A second fabrication step for forming the second light-emitting element, The process comprises a third manufacturing step for forming the aforementioned third light-emitting element, The first manufacturing step is, A step of sequentially forming a first conductive film, a first EL layer, a second conductive film, and a first layer, A step of forming a first resist mask on the first layer, Using the first resist mask, a portion of each of the first conductive film, the first EL layer, the second conductive film, and the first layer is selectively removed to form the anode of the first light-emitting element, the first EL layer, the second conductive film, and the first layer stacked together, and an eleventh conductive film. A step of removing a portion of the first resist mask, A step of using a first resist mask from which a portion has been removed to selectively remove the other portions of the first EL layer, the second conductive film, and the first layer located on the anode of the first light-emitting element, thereby forming the EL layer of the first light-emitting element and the cathode of the first light-emitting element. The process includes removing the first resist mask from which the aforementioned portion has been removed, The second manufacturing step is, The process involves sequentially forming a second EL layer, a third conductive layer, and a second layer on the eleventh conductive film, A step of forming a second resist mask on the second layer, Using the second resist mask, a portion of each of the 11th conductive film, the 2nd EL layer, the 3rd conductive film, and the 2nd layer is selectively removed to form the anode of the 2nd light-emitting element, the 2nd EL layer, the 3rd conductive film, and the 2nd layer, and the 12th conductive film. A step of removing a portion of the second resist mask, A step of using a second resist mask from which a portion has been removed to selectively remove the other portions of the second EL layer, the third conductive film, and the second layer located on the anode of the second light-emitting element, thereby forming the EL layer and the cathode of the second light-emitting element. The process includes removing a second resist mask from which the aforementioned portion has been removed, The third manufacturing step is: The process involves sequentially forming a third EL layer, a fourth conductive layer, and a third layer on the twelfth conductive film, A step of forming a third resist mask on the third layer, A step of selectively removing a portion of the 12th conductive film, the 3rd EL layer, the 4th conductive film, and the 3rd layer using the 3rd resist mask to form a stack of the anode, 3rd EL layer, 4th conductive film, and 3rd layer of the 3rd light-emitting element, A step of removing a portion of the third resist mask, A step of using a third resist mask from which a portion has been removed to selectively remove the other portions of the third EL layer, the fourth conductive film, and the third layer located on the anode of the third light-emitting element, thereby forming the EL layer of the third light-emitting element and the cathode of the third light-emitting element. A method for manufacturing a display device, comprising the step of removing a third resist mask from which the aforementioned portion has been removed.

2. Each of the first to third resist masks is formed using a multi-level mask. A method for manufacturing the display device described in claim 1.

3. In the second manufacturing step, The second EL layer, the third conductive film, and the second layer are Formed to cover the first light-emitting element, A method for manufacturing a display device according to claim 1 or claim 2.

4. In the third manufacturing step described above, The third EL layer, the fourth conductive film, and the third layer are A structure formed covering the first light-emitting element and the second light-emitting element, A method for manufacturing a display device according to any one of claims 1 to 3.

5. Each of the first to third EL layers includes an organic EL material. A method for manufacturing a display device according to any one of claims 1 to 4.

6. After the completion of the first to third manufacturing steps, The process includes a step of forming a fourth layer that covers the first to third light-emitting elements, A method for manufacturing a display device according to any one of claims 1 to 5.

7. The process includes a step of forming a fifth conductive film that is electrically connected to the cathode of the first light-emitting element, the cathode of the second light-emitting element, and the cathode of the third light-emitting element. A method for manufacturing a display device according to any one of claims 1 to 6.

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