Semiconductor equipment

Abstract

We provide semiconductor equipment with a high manufacturing yield. [Solution] A semiconductor device having a plurality of sub-pixels. Each sub-pixel has a first transistor, a second transistor, a first to third capacitance element, a first insulating layer, and wiring. Each of the first to third capacitance elements has a first conductive layer, a second conductive layer, and a second insulating layer sandwiched between the first and second conductive layers. The first insulating layer is provided on the first transistor and the second transistor. The first conductive layer of the first to third capacitance elements and the wiring are each provided on the first insulating layer. In a top view, the ratio of the total area of ​​the first conductive layer of the first to third capacitance elements and the wiring to the area of ​​the sub-pixel is 15 percent or more. The area of ​​the first conductive layer of the second capacitance element and the area of ​​the first conductive layer of the third capacitance element are each at least twice the area of ​​the first conductive layer of the first capacitance element.

Description

[Technical Field]

[0001] One aspect of the present invention relates to a semiconductor device.

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

[0003] 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 also contain semiconductor devices. [Background technology]

[0004] In recent years, there has been a growing demand for display devices applicable to virtual reality (VR), augmented reality (AR), substitutional reality (SR), or mixed reality (MR).

[0005] VR, AR, SR, and MR are collectively referred to as xR (Extended Reality). Display devices for xR are desired to have high resolution and high color reproduction in order to enhance the sense of reality and immersion. Examples of such display devices include liquid crystal displays, organic EL (Electro-Luminescence) elements, and light-emitting diodes (LEDs) and other light-emitting devices.

[0006] For example, the basic structure of an organic EL device is one in which a layer containing a light-emitting organic compound is sandwiched between a pair of electrodes. By applying a voltage to this device, light emission can be obtained from the light-emitting organic compound. A display device to which such an organic EL device is applied does not require a backlight, which was necessary in a liquid crystal display device or the like, and thus can realize a thin, lightweight, high-contrast, and low-power consumption display device. In addition, since the response speed of the organic EL device is fast, a display device suitable for displaying fast-moving images can be realized. For example, an example of a display device using an organic EL device is described in Patent Document 1.

[0007] In Patent Document 2, a circuit configuration is disclosed that corrects the threshold voltage variation of transistors for each pixel in a pixel circuit that controls the light emission luminance of an organic EL device, thereby improving the display quality of the display device.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0009] One aspect of the present invention aims to provide a semiconductor device or display device with a high manufacturing yield. Alternatively, it aims to provide a compact semiconductor device or display device. Alternatively, one aspect of the present invention aims to provide a semiconductor device or display device with high display quality. Alternatively, it aims to provide a semiconductor device or display device with high color reproducibility. Alternatively, it aims to provide a high-definition semiconductor device or display device. Alternatively, it aims to provide a highly reliable semiconductor device or display device. Alternatively, one aspect of the present invention aims to provide a semiconductor device or display device with low power consumption. Alternatively, it aims to provide a novel semiconductor device or display 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 can be identified from the description in the specification, drawings, claims, etc. [Means for solving the problem]

[0011] One aspect of the present invention is a semiconductor device having a display unit. The display unit has a plurality of sub-pixels. Each of the plurality of sub-pixels has a first transistor, a second transistor, a first capacitive element, a second capacitive element, a third capacitive element, a first insulating layer, and wiring. The first transistor is electrically connected to the second transistor, the first capacitive element, the second capacitive element, and the third capacitive element. Each of the first to third capacitive elements has a first conductive layer, a second conductive layer, and a second insulating layer sandwiched between the first conductive layer and the second conductive layer. The first insulating layer is provided on the first transistor and the second transistor. The first conductive layer and wiring of the first to third capacitive elements are each provided on the first insulating layer. In a top view, the ratio of the total area of ​​the first conductive layer of the first to third capacitive elements and the wiring to the area of ​​the subpixel is 15% or more. The area of ​​the first conductive layer of the second capacitive element is at least twice the area of ​​the first conductive layer of the first capacitive element. The area of ​​the first conductive layer of the third capacitive element is at least twice the area of ​​the first conductive layer of the first capacitive element.

[0012] In the aforementioned semiconductor device, it is preferable to have a substrate and a third transistor. The first to third transistors are each provided on the substrate. The third transistor is electrically floating. The first to third transistors each have a semiconductor layer. In a top view, it is preferable that the ratio of the total area of ​​the semiconductor layers of the first to third transistors to the area of ​​the subpixels is 15% or more.

[0013] In the aforementioned semiconductor device, it is preferable that the semiconductor layer of the third transistor has a region shared with the semiconductor layer of the first transistor.

[0014] In the aforementioned semiconductor device, it is preferable that there be multiple third transistors.

[0015] In the semiconductor device described above, it is preferable that one of the source or drain of the first transistor is electrically connected to one terminal of the first capacitive element. It is preferable that the gate of the first transistor is electrically connected to the other terminal of the first capacitive element. It is preferable that the other of the source or drain of the first transistor is electrically connected to one of the source or drain of the second transistor, one terminal of the second capacitive element, and one terminal of the third capacitive element. It is preferable that the gate of the second transistor is electrically connected to the other terminal of the second capacitive element. It is preferable that the back gate of the second transistor is electrically connected to the other terminal of the third capacitive element.

[0016] In the aforementioned semiconductor device, the second transistor is preferably a multi-channel transistor.

[0017] In the aforementioned semiconductor device, it is preferable to have a light-emitting device. Preferably, one terminal of the light-emitting device is electrically connected to either the source or the drain of the first transistor.

[0018] In the semiconductor device described above, it is preferable that one or more of the first transistor and the second transistor include a metal oxide in the semiconductor layer.

[0019] In the aforementioned semiconductor device, the metal oxide preferably contains one or more of indium and zinc.

[0020] In the semiconductor device described above, it is preferable that the second transistor comprises a semiconductor layer, a first conductor and a second conductor arranged on the semiconductor layer at a distance from each other, a first insulator arranged on the first conductor and the second conductor with an opening formed between the first conductor and the second conductor, a third conductor arranged in the opening of the first insulator, and a second insulator arranged between the semiconductor layer, the first conductor, the second conductor, the first insulator, and the third conductor. [Effects of the Invention]

[0021] According to one aspect of the present invention, a semiconductor device or display device with a high manufacturing yield can be provided. Alternatively, a compact semiconductor device or display device can be provided. Alternatively, one aspect of the present invention can provide a semiconductor device or display device with high display quality. Alternatively, a semiconductor device or display device with high color reproducibility can be provided. Alternatively, a high-definition semiconductor device or display device can be provided. Alternatively, a highly reliable semiconductor device or display device can be provided. Alternatively, one aspect of the present invention can provide a semiconductor device or display device with low power consumption. Alternatively, a novel semiconductor device or display device can be provided.

[0022] Furthermore, the description of these effects does not preclude the existence of other effects. Moreover, one aspect of the present invention does not necessarily have to possess all of these effects. Other effects can be extracted from the description in the specification, drawings, claims, etc. [Brief explanation of the drawing]

[0023] [Figure 1] Figures 1A and 1B are perspective views of the display device. [Figure 2] Figure 2 is a cross-sectional view showing an example of the configuration of a display device. [Figure 3] Figures 3A and 3B are top views showing examples of the configuration of a display device. [Figure 4] Figure 4 is a circuit diagram illustrating a semiconductor device. [Figure 5] Figures 5A to 5C show the circuit symbols for transistors. [Figure 6] Figure 6 is a circuit diagram illustrating a semiconductor device. [Figure 7] Figure 7 is a top view illustrating a semiconductor device. [Figure 8] Figure 8 is a top view illustrating a semiconductor device. [Figure 9] Figure 9 is a top view illustrating a semiconductor device. [Figure 10] Figure 10 is a top view illustrating a semiconductor device. [Figure 11] Figure 11 is a top view illustrating a semiconductor device. [Figure 12] Figures 12A and 12B are top views illustrating a semiconductor device. [Figure 13] Figures 13A and 13B are top views illustrating a semiconductor device. [Figure 14] Figures 14A and 14B are top views illustrating a semiconductor device. [Figure 15] Figures 15A and 15B are top views illustrating a semiconductor device. [Figure 16] Figures 16A to 16G are top views illustrating examples of pixel configurations. [Figure 17] Figures 17A and 17B are top views illustrating a semiconductor device. [Figure 18] Figures 18A and 18B are top views illustrating a semiconductor device. [Figure 19] Figure 19 is a timing chart illustrating the operation of a semiconductor device. [Figure 20] Figure 20 is a diagram illustrating the operation of a semiconductor device. [Figure 21] Figure 21 is a diagram illustrating the operation of a semiconductor device. [Figure 22] Figure 22 is a diagram illustrating the operation of a semiconductor device. [Figure 23] Figure 23 is a diagram illustrating the operation of a semiconductor device. [Figure 24] Figure 24 is a diagram illustrating the operation of a semiconductor device. [Figure 25] Figure 25 is a diagram illustrating the operation of a semiconductor device. [Figure 26] Figures 26A to 26D illustrate examples of the configuration of a light-emitting device. [Figure 27] Figures 27A to 27D show examples of the configuration of a light-emitting device. [Figure 28] Figures 28A to 28D show examples of the configuration of a light-emitting device. [Figure 29] Figures 29A and 29B show examples of the configuration of a light-emitting device. [Figure 30] Figure 30 is a cross-sectional view showing an example of the configuration of a display device. [Figure 31] Figure 31 is a cross-sectional view showing an example of the configuration of a display device. [Figure 32] Figure 32 is a cross-sectional view showing an example of the configuration of a display device. [Figure 33] Figure 33 is a cross-sectional view showing an example of the configuration of a display device. [Figure 34] Figure 34A is a top view showing an example of a transistor configuration. Figures 34B and 34C are cross-sectional views showing an example of a transistor configuration. [Figure 35] Figure 35A illustrates the classification of crystal structures. Figure 35B illustrates the XRD spectrum of the CAAC-IGZO film. Figure 35C illustrates the micro-electron diffraction pattern of the CAAC-IGZO film. [Figure 36] Figures 36A to 36F illustrate an example of an electronic device. [Figure 37] Figures 37A to 37F illustrate an example of an electronic device. [Figure 38] Figures 38A and 38B illustrate an example of an electronic device. [Figure 39] Figure 39 is a diagram illustrating an example of an electronic device. [Figure 40] Figure 40A shows the electrical characteristics of this embodiment, and Figure 40B shows the variation in the electrical characteristics of this embodiment. [Figure 41] Figures 41A and 41B show the variation in electrical characteristics according to this embodiment. [Figure 42] Figures 42A and 42B show the reliability according to this embodiment. [Figure 43] Figures 43A and 43B show the reliability according to this embodiment. [Figure 44] Figures 44A and 44B show the reliability according to this embodiment. [Figure 45] Figures 45A and 45B are optical microscope images according to this embodiment. [Modes for carrying out the invention]

[0024] The embodiments will be described below 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 construed as being limited to the contents of the following embodiments.

[0025] In this specification, when it is stated that X and Y are connected, it is understood that this specification discloses the following types of connections: an electrical connection between X and Y, a functional connection between X and Y, and a direct connection between X and Y. Therefore, it is understood that the disclosure in the specification includes not only predetermined connection relationships, such as those shown in the figures or text, but also other connection relationships. X and Y are defined as objects (e.g., devices, elements, circuits, wiring, electrodes, terminals, conductive films, layers, etc.).

[0026] One example of a case where X and Y are electrically connected is that one or more elements that enable the 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.

[0027] 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.

[0028] 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).

[0029] 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.).

[0030] 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.

[0031] 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. Furthermore, terms such as "capacitive element," "parasitic capacitance," and "gate capacitance" can be replaced with terms such as "capacitance," and conversely, the term "capacitance" can be replaced with terms such as "capacitive element," "parasitic capacitance," and "gate capacitance." Also, the term "a pair of electrodes" in "capacitance" can be replaced with terms such as "a pair of conductors," "a pair of conductive regions," and "a pair of regions."

[0032] In this specification, a transistor has three terminals called the gate, source, and drain. The gate is a control terminal that controls the amount of current flowing between the source and drain. 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 or p-channel) and the potential difference between 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. In addition, when describing the connection relationships of a transistor, this specification uses the notation "one of the source or drain" (or the first electrode or first terminal) and "the other of the source or drain" (or the second electrode or second terminal). Depending on the structure of the transistor, there may be a back gate in addition to the three terminals described above. 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.

[0033] 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. Furthermore, terminals, wiring, etc., can be replaced with "node."

[0034] In this specification, the ordinal numbers "1st," "2nd," and "3rd" 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.

[0035] 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. Furthermore, the positional relationship between components changes as appropriate depending on the direction in which each component is depicted. Therefore, the phrases described 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.

[0036] The terms "above" and "below" do not limit the relative positions 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 directly in contact with insulating layer A, and does not exclude cases where other components are present between insulating layer A and electrode B.

[0037] In this specification, terms such as "overlapping" do not limit the stacking order or other states of the constituent elements. For example, the expression "electrode B overlapping insulating layer A" does not exclude not only the state in which electrode B is formed on top of insulating layer A, but also the state in which electrode B is formed below insulating layer A, or the state in which electrode B is formed to the right (or left) of insulating layer A, etc.

[0038] In this specification, the terms "adjacent" and "proximity" are not limited to direct contact between components. For example, the expression "electrode B adjacent to insulating layer A" does not require that insulating layer A and electrode B be formed in direct contact, and does not exclude cases where other components are included between insulating layer A and electrode B.

[0039] In this specification, terms such as "film" and "layer" can be interchanged as appropriate. 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, the term "conductor" may be changed to the term "conductive layer" or "conductive film." Alternatively, for example, the term "insulating layer" or "insulating film" may be changed to the term "insulator." Or, the term "insulator" may be changed to the term "insulating layer" or "insulating film."

[0040] 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. Furthermore, 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 context.

[0041] In this specification, terms such as "wiring," "signal line," and "power line" can be interchanged with each other depending on the circumstances. For example, the term "wiring" may be changed to the term "signal line." Similarly, the term "wiring" may be changed to the term "power line," and vice versa. Terms such as "power line" may be changed to the term "wiring." Terms such as "power line" may be changed to the term "signal line," and vice versa. In addition, the term "potential" applied to the wiring may be changed to the term "signal," and vice versa.

[0042] In this specification, a "switch" is defined as having multiple terminals and having the function of switching (selecting) between continuity and non-continuity between the terminals. For example, if a switch has two terminals and there is continuity between both terminals, the switch is said to be in a "conductive state" or "on state." If there is no continuity between both terminals, the switch is said to be in a "non-conductive state" or "off state." Switching to either a continuative or non-conductive state, or maintaining either a continuative or non-conductive state, may be referred to as "controlling the continuity state."

[0043] In short, a switch is a device that controls whether or not an electric current flows. Alternatively, a switch is a device that selects and switches the path through which an electric current flows. Examples include electrical switches and mechanical switches. In other words, a switch can be anything that can control an electric current, and is not limited to any particular type.

[0044] Examples of 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" or "on 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" or "off 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 used simply as a switch, the polarity (conductivity type) of the transistor is not particularly limited.

[0045] One example of a mechanical switch is a switch using MEMS (Micro-Electro-Mechanical Systems) technology. This switch has mechanically movable electrodes, and the movement of these electrodes selects between conductivity and non-conductivity.

[0046] 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.

[0047] In this specification, when count values ​​and measured values ​​are referred to as "identical," "same," "equal," or "uniform" (including synonyms thereof), unless otherwise explicitly stated, this refers to a margin of error of plus or minus 20%.

[0048] 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, when referring to similar functions, the hatch patterns may be the same, and reference numerals may not be assigned. Furthermore, in order to make the drawings easier to understand, some components may be omitted in perspective views or top views (also called plan views).

[0049] In the drawings and other illustrations relating to 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. Furthermore, 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.

[0050] In drawings and other illustrations relating to this specification, arrows indicating the X, Y, and Z directions may be included. In this specification, the "X direction" refers to the direction along the X-axis, and unless explicitly stated, the forward and reverse directions may not be distinguished. The same applies to the "Y direction" and "Z direction." Furthermore, the X, Y, and Z directions are directions that intersect each other. More specifically, the X, Y, and Z directions are directions that are orthogonal to each other. In this specification, one of the X, Y, or Z directions may be referred to as the "first direction" or "first direction." Another may be referred to as the "second direction" or "second direction." The remaining one may be referred to as the "third direction" or "third direction."

[0051] In this specification, when the same symbol is used for multiple elements, and especially when it is necessary to distinguish them, an identifying symbol such as "A", "b", "_1", "[n]", or "[m,n]" may be added to the symbol.

[0052] (Embodiment 1) A semiconductor device according to one aspect of the present invention will now be described. This semiconductor device according to one aspect of the present invention can be suitably used, for example, as a pixel in a display device.

[0053] A semiconductor device according to one aspect of the present invention has a display unit. The display unit has a plurality of sub-pixels. Each of the plurality of sub-pixels has a first transistor, a second transistor, a first capacitive element, a second capacitive element, a third capacitive element, a first insulating layer, and wiring. The first transistor is electrically connected to the second transistor, the first capacitive element, the second capacitive element, and the third capacitive element.

[0054] Each of the first to third capacitance elements has a first conductive layer that functions as a lower electrode, a second conductive layer that functions as an upper electrode, and a second insulating layer sandwiched between the first and second conductive layers. The first insulating layer is provided on the first and second transistors. The first conductive layer and wiring of each of the first to third capacitance elements are provided on the first insulating layer.

[0055] In a top view, it is preferable that the ratio of the total area of ​​the first conductive layer of the first to third capacitive elements and the wiring to the area of ​​the subpixel is 15% or more. Furthermore, it is preferable that the area of ​​the first conductive layer of the second capacitive element is at least twice the area of ​​the first conductive layer of the first capacitive element. It is also preferable that the area of ​​the first conductive layer of the third capacitive element is at least twice the area of ​​the first conductive layer of the first capacitive element.

[0056] In one aspect of the present invention, it is preferable that the area of ​​the first to third capacitance elements in the semiconductor device is large. For example, a display device to which this semiconductor device is applied can be small and achieve high color reproduction. Furthermore, by increasing the area of ​​the first to third capacitance elements, the proportion of the resist mask area in the manufacturing process increases, and the generation of foreign matter caused by the resist mask can be suppressed. Therefore, pattern defects can be reduced, and the manufacturing yield of the semiconductor device can be increased. In addition, by providing dummy transistors, the generation of foreign matter can be similarly suppressed in the transistor manufacturing process, and the manufacturing yield can be increased.

[0057] <Configuration Example 1> Figure 1A shows a perspective view of a display device to which a semiconductor device according to one aspect of the present invention is applied. The display device 10 shown in Figure 1A has a display area 235, a first drive circuit section 231, and a second drive circuit section 232.

[0058] The display area 235 has a plurality of pixels 230 arranged in a matrix. Each of the plurality of pixels 230 has a light-emitting device. Preferably, an OLED (Organic Light Emitting Diode) or a QLED (Quantum-dot Light Emitting Diode) is used as the light-emitting device. Examples of light-emitting materials for the light-emitting device include fluorescent materials, phosphorescent materials, inorganic compounds (quantum dot materials, etc.), and thermally activated delayed fluorescence (TADF) materials. Alternatively, an LED (Light Emitting Diode) can also be used as the light-emitting device.

[0059] The first drive circuit section 231 functions, for example, as a scan line drive circuit. The second drive circuit section 232 functions, for example, as a signal line drive circuit. Other circuits may be provided at a position facing the first drive circuit section 231 across the display area 235. Other circuits may be provided at a position facing the second drive circuit section 232 across the display area 235. The first drive circuit section 231 and the second drive circuit section 232 are sometimes collectively referred to as the "peripheral drive circuit".

[0060] 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. Furthermore, the transistors and capacitive elements in the peripheral drive circuit and the transistors and capacitive elements in the pixel 230 can be formed using the same process.

[0061] The display device 10 may have an input / output terminal section 29. Power and signals necessary for the operation of the display device 10 can be supplied to the display device 10 via the input / output terminal section 29.

[0062] The display device 10 can have a stacked structure of layer 50 and layer 60 on top of layer 50. Layer 50 has a plurality of pixel circuits 51 arranged in a matrix, a first drive circuit section 231, a second drive circuit section 232, and an input / output terminal section 29. Layer 60 has a plurality of light-emitting devices 61 arranged in a matrix. One pixel circuit 51 and one light-emitting device 61 are electrically connected and can function as one pixel 230. Furthermore, by combining multiple pixels 230 exhibiting different colors and making them function as a single pixel, full-color display can be achieved. In this case, each pixel 230 functions as a sub-pixel.

[0063] As shown in Figure 1B, the display device 10 may have a stacked structure of layer 40, layer 50 on layer 40, and layer 60 on layer 50. Figure 1B shows a configuration in which a plurality of pixel circuits 51 arranged in a matrix are provided on layer 50, and a first drive circuit unit 231 and a second drive circuit unit 232 are provided on layer 40. By providing the first drive circuit unit 231 and the second drive circuit unit 232 on different layers from the pixel circuits 51, the width of the frame around the display area 235 can be narrowed, and the area of ​​the display area 235 can be increased.

[0064] By increasing the area of ​​the display area 235, the resolution of the display area 235 can be increased. If the resolution of the display area 235 remains constant, the area of ​​one pixel can be increased. Therefore, the luminescence brightness of the display area 235 can be increased. In addition, the ratio of the area of ​​the light-emitting region to one pixel (also called the aperture ratio) can be increased. For example, the aperture ratio of a pixel can be set to 40% or more and less than 100%, preferably 50% or more and 95%, and more preferably 60% or more and 95%. Furthermore, by increasing the area of ​​one pixel, the current density supplied to the light-emitting device 61 can be reduced. Therefore, the load on the light-emitting device 61 is reduced, thereby increasing the reliability of the light-emitting device 61 and the reliability of the display device 10.

[0065] By stacking the display area 235 and the peripheral drive circuit, the wiring connecting them electrically can be shortened. Therefore, wiring resistance and parasitic capacitance are reduced, and the operating speed of the display device 10 can be increased. Furthermore, the power consumption of the display device 10 is reduced.

[0066] Layer 40 may include not only peripheral drive circuits but also one or more of a CPU 23 (Central Processing Unit), a GPU 24 (Graphics Processing Unit), and a memory circuit section 25. In this embodiment, the peripheral drive circuits, CPU 23, GPU 24, and memory circuit section 25 are collectively referred to as "functional circuits."

[0067] For example, the CPU 23 has the function of controlling the operation of the GPU 24 and the circuits provided in layer 40 according to a program stored in the memory circuit unit 25. The GPU 24 has the function of performing calculations to form image data. In addition, the GPU 24 can perform many matrix operations (multiply-accumulate operations) in parallel, so it can perform calculations using neural networks at high speed, for example. The GPU 24 has the function of correcting image data using correction data stored in the memory circuit unit 25, for example. For example, the GPU 24 has the function of generating image data with corrected brightness, hue, and / or contrast.

[0068] Image data may be upconverted or downconverted using the GPU24. Alternatively, a super-resolution circuit may be provided in layer 40. The super-resolution circuit has the function of determining the potential of any pixel in the display area 235 by sum-of-products operation of the potentials and weights of the surrounding pixels. The super-resolution circuit has the function of upconverting image data with a resolution lower than that of the display area 235. The super-resolution circuit also has the function of downconverting image data with a resolution higher than that of the display area 235.

[0069] By incorporating a super-resolution circuit, the load on the GPU24 can be reduced. For example, the GPU24 can process up to 2K resolution (or 4K resolution), and then the super-resolution circuit can upconvert it to 4K resolution (or 8K resolution), thereby reducing the load on the GPU24. Downconversion can be done in the same way.

[0070] The functional circuits of layer 40 do not necessarily have to include all of these configurations, and may include other configurations. For example, they may include a potential generation circuit that generates multiple different potentials, and / or a power management circuit that controls the supply and stop of power for each circuit of the display device 10.

[0071] Power supply and deactivation may be performed for each circuit that makes up the CPU 23. For example, power consumption can be reduced by deactivating the power supply to a circuit that is determined not to be used for a while and reactivating the power supply when needed. The data required when reactivating the power supply can be stored in the memory circuit within the CPU 23 or in the memory circuit unit 25 before the circuit is deactivated. By storing the data required when the circuit is restored, a high-speed restoration of a deactivated circuit can be achieved. Alternatively, circuit operation may be stopped by deactivating the supply of a clock signal.

[0072] The functional circuitry may include a DSP circuit, a sensor circuit, a communication circuit, and / or an FPGA (Field Programmable Gate Array).

[0073] Figure 2 shows an example of the cross-sectional configuration of the display device 10. Figure 2 shows an excerpt of a portion of the pixels 230. The display device 10 has a substrate 69, a layer 50 including a transistor 71 and a capacitive element 73, and a layer 60 including a light-emitting device 61. The layer 50 also has multiple wirings.

[0074] A transistor 71 is provided on the substrate 69. An insulating layer 288 is provided on the transistor 71. A capacitive element 73 is provided on the insulating layer 288. As shown in Figure 2, it is preferable that the capacitive element 73 has a region that overlaps with the transistor 71. By having a region that overlaps with the transistor 71, the area of ​​the pixel 230 can be reduced, resulting in a high-definition display device. An insulating layer 290 is provided on the capacitive element 73. A light-emitting device 61 is provided on the insulating layer 290. It is preferable that the light-emitting device 61 has a region that overlaps with the transistor 71 and a region that overlaps with the capacitive element 73. By having a region that overlaps with the transistor 71 and the capacitive element 73, the aperture ratio can be increased. In addition, insulating layers 291 and 293 may be provided between the insulating layer 290 and the light-emitting device 61.

[0075] The substrate 69 can be an insulating substrate or a semiconductor substrate.

[0076] An insulating layer 283 is provided on the substrate 69. The insulating layer 283 functions as a barrier layer to prevent impurities such as water or hydrogen from diffusing from the substrate 69 to the transistor 71. The insulating layer 283 can be one or more of the following: an aluminum oxide film, a hafnium oxide film, and a silicon nitride film.

[0077] A transistor 71 is provided on the insulating layer 283. The transistor 71 has a conductive layer 75 that functions as a back gate, insulating layers 77a and 77b that function as a first gate insulating layer, a semiconductor layer 79, an insulating layer 81 that functions as a second gate insulating layer, a conductive layer 83 that functions as a gate, and a pair of conductive layers 85. The pair of conductive layers 85 are provided in contact with the semiconductor layer 79 and function as a source electrode and a drain electrode. Wiring 75A is also provided on the insulating layer 283. Wiring 75A can be formed in the same process as the conductive layer 75.

[0078] Figure 2 shows a laminated structure of insulating layer 77a and insulating layer 77b on insulating layer 77a as the first gate insulating layer, but the present invention is not limited to this. The first gate insulating layer may be a single layer or a laminated structure of three or more layers. Similarly, the conductive layer 75, semiconductor layer 79, insulating layer 81, conductive layer 83, and conductive layer 85 may each be a single layer or a laminated structure.

[0079] The conductive layer 75 can be provided so as to be embedded in the insulating layer 284. Planarization treatment can be performed so that the height of the upper surface of the conductive layer 75 matches or approximately matches the height of the insulating layer 284.

[0080] An insulating layer 285 is provided covering the upper and side surfaces of the conductive layer 85 and the side surfaces of the semiconductor layer 79, and an insulating layer 286 is provided on top of the insulating layer 285. Preferably, the height of the upper surface of the insulating layer 286 is the same as or approximately the same as the height of the upper surface of the conductive layer 83 and the upper surface of the insulating layer 81.

[0081] An insulating layer 287 is provided on the insulating layer 286, and an insulating layer 288 is provided on the insulating layer 287.

[0082] A capacitive element 73 is provided on the insulating layer 288. The capacitive element 73 has a conductive layer 87 that functions as a lower electrode, a conductive layer 89 that functions as an upper electrode, and an insulating layer 91. The insulating layer 91 is sandwiched between the conductive layers 87 and 89 and functions as a dielectric for the capacitive element 73. Conductive layers 87A and 87B are also provided on the insulating layer 288. Conductive layers 87A and 87B can be formed in the same process as conductive layer 87.

[0083] Plugs 274A are provided so as to be embedded in insulating layers 288, 287, 286, and 285. Figure 2 shows an example configuration in which the capacitive element 73 is electrically connected to either the source or drain of the transistor 71 via plugs 274A.

[0084] An insulating layer 289 is provided on the capacitive element 73, and an insulating layer 290 is provided on the insulating layer 289. A plug 274B is provided so as to be embedded in the insulating layer 289 and the insulating layer 290. Wiring 279 is provided on the insulating layer 290. An insulating layer 291 is provided on the wiring 279. A plug 274C is provided so as to be embedded in the insulating layer 291. Wiring 281 is provided on the insulating layer 291. An insulating layer 293 is provided on the wiring 281. A plug 274D is provided so as to be embedded in the insulating layer 293.

[0085] A light-emitting device 61 is provided on the wiring 281. The light-emitting device 61 has a conductive layer 63, a conductive layer 67, and an EL layer 65. The EL layer 65, sandwiched between the conductive layer 63 and the conductive layer 67, has at least a light-emitting layer. The light-emitting layer has a light-emitting material that emits light. By applying a voltage between the conductive layer 63 and the conductive layer 67, light is emitted from the EL layer 65. Figure 2 shows a configuration in which the light-emitting device 61 is electrically connected to the capacitive element 73 via plug 274B, wiring 279, plug 274C, wiring 281, and plug 274D. The conductive layer 63 functions as a pixel electrode of the light-emitting device 61, and the conductive layer 67 functions as a common electrode.

[0086] The display device 10 preferably has a transistor that does not contribute to the operation of the display device 10 (hereinafter also referred to as a dummy transistor). The dummy transistor has a laminated structure of a semiconductor layer, a conductive layer, and an insulating layer sandwiched between the semiconductor layer and the conductive layer, and one or more of its gate, drain, and source are electrically floating. The display device 10 may also have a layer that does not contribute to the operation of the display device 10 (hereinafter also referred to as a dummy layer). As a dummy layer, for example, a conductive layer that does not function as wiring, that is, electrically floating, can be provided. Alternatively, a semiconductor layer that is electrically floating can be provided as a dummy layer.

[0087] Figure 2 shows a dummy transistor 71DM, dummy layer 75DMb, dummy layer 87DM, dummy layer 89DM, dummy layer 279DM, and dummy layer 281DM. The dummy transistor 71DM is provided on an insulating layer 283 and has a conductive layer 75DMa, an insulating layer 77a, an insulating layer 77b, a semiconductor layer 79DM, an insulating layer 81DM, a conductive layer 83DM, and a pair of conductive layers 85DM.

[0088] The dummy transistor 71DM can be formed using the same process as transistor 71. For example, the conductive layer 75DMa can be formed using the same process as conductive layer 75. Furthermore, the dummy layer 75DMb may be formed during the formation of conductive layers 75 and 75DMa. While Figure 2 shows a configuration where the semiconductor layer 79 of transistor 71 and the semiconductor layer of dummy transistor 71DM are separated, the present invention is not limited to this configuration. The semiconductor layer 79 and semiconductor layer 79DM may not be separated; that is, transistor 71 and dummy transistor 71DM may share a single semiconductor layer.

[0089] The dummy layer 87DM is provided on the insulating layer 288 and can be formed in the same process as the conductive layer 87. The dummy layer 89DM is provided on the insulating layer 91 and can be formed in the same process as the conductive layer 89. The dummy layer 279DM is provided on the insulating layer 290 and can be formed in the same process as the wiring 279. The dummy layer 281DM is provided on the insulating layer 291 and can be formed in the same process as the wiring 281.

[0090] A single pixel may have multiple dummy transistors. Alternatively, multiple dummy layers may be provided on the same insulating layer. Figure 2 shows a configuration in which two dummy layers 281DM are provided on the insulating layer 291.

[0091] Here, the layers of the display device 10 can be formed using photolithography. For example, a semiconductor layer can be formed by etching a semiconductor film, which will become the semiconductor layer, using a resist mask formed on the semiconductor film as a mask. For etching, one or more of the following methods can be used: dry etching, wet etching, and sandblasting. Conductive layers and insulating layers can be formed in a similar manner.

[0092] A resist mask can be formed by applying a photosensitive resist material to a film to be processed, followed by exposure and development. Negative or positive resist materials can be used. Chemically amplified resist materials may also be used. For development, for example, TMAH (Tetra Methyl Ammonium Hydroxide) can be used. A strong alkaline aqueous solution with added surfactant may also be used for development.

[0093] In photolithography, the light used for exposure can be, for example, i-line (wavelength 365 nm), g-line (wavelength 436 nm), h-line (wavelength 405 nm), or a mixture thereof. Ultraviolet light, KrF laser light, or ArF laser light can also be used. Exposure may also be performed using immersion lithography. Extreme ultraviolet (EUV) light or X-rays may be used as the light for exposure. Alternatively, an electron beam can 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.

[0094] During development, polymer components of the resist mask may leach into the developer solution and further aggregate to form foreign matter, which may adhere to the processed film. Additionally, developer solution that penetrates the resist mask during development may leach out during subsequent washing, causing polymer components of the resist mask to leach out and become foreign matter. This is particularly true for hydrophilic films, which are more susceptible to foreign matter adhesion. If foreign matter adheres to areas without a resist mask, it may act as a mask during etching, potentially causing pattern defects. Furthermore, pattern defects could lead to short circuits.

[0095] In one aspect of the present invention, a semiconductor device can increase the proportion of the total area of ​​the resist mask provided on the workpiece by providing a dummy transistor or dummy layer. Therefore, the proportion of the area of ​​the workpiece that is not covered by the resist mask and is exposed is reduced, and the adhesion of foreign matter caused by the resist mask to that area can be suppressed. In other words, pattern defects can be reduced and the manufacturing yield of the semiconductor device can be increased.

[0096] When manufacturing semiconductor devices, it is preferable that the ratio of the total area of ​​the resist mask provided on the workpiece is high. In a top view, the ratio of the total area of ​​the resist mask to the area of ​​the region where the pixel circuit 51 is provided is preferably 10% or more, more preferably 12% or more, more preferably 15% or more, more preferably 17% or more, more preferably 20% or more, more preferably 25% or more, more preferably 30% or more, and more preferably 40% or more. The ratio of the total area of ​​the resist mask can be increased by providing dummy transistors or dummy layers in areas where transistors, capacitive elements, and various wirings are not placed. If the ratio of the total area of ​​the resist mask falls within the above range without providing dummy transistors or dummy layers, then dummy transistors or dummy layers may not be provided. Furthermore, the ratio of the total area of ​​the resist mask does not have to be within the above range in all photolithography processes. Although it is preferable that the ratio of the total area of ​​the resist mask be high, if the ratio of the total area of ​​the resist mask is high, pattern defects may occur due to foreign matter other than foreign matter caused by the resist mask as described above. Therefore, when setting an upper limit on the percentage of the total area of ​​the resist mask, it is preferable that it be 90% or less, more preferably 80% or less, and even more preferably 70% or less. However, there is no particular need to set an upper limit on the percentage of the total area of ​​the resist mask used for contact hole formation.

[0097] In this specification, the area of ​​the region where the pixel circuit 51 is provided in a top view may be referred to as the area of ​​a pixel or the area of ​​a sub-pixel.

[0098] It is preferable that the ratio of the total area of ​​the layers provided on the same surface is high. In a top view, the ratio of the total area of ​​the layers to the area of ​​the pixel 230 is preferably 10% or more, more preferably 12% or more, more preferably 15% or more, more preferably 17% or more, more preferably 20% or more, more preferably 25% or more, more preferably 30% or more, and more preferably 40% or more. Figure 3A shows a top view example of the configuration of the conductive layer 87, conductive layer 87A, conductive layer 87B, and dummy layer 87DM shown in Figure 2. The conductive layer 87, conductive layer 87A, conductive layer 87B, and dummy layer 87DM are all provided on the insulating layer 288. It is preferable that the ratio of the total area of ​​the conductive layer 87, conductive layer 87A, conductive layer 87B, and dummy layer 87DM to the area of ​​the pixel 230 be within the range described above. Furthermore, although conductive layer 87, conductive layer 87A, conductive layer 87B, and dummy layer 87DM were used as examples in this explanation, it is preferable that the ratio of the total area of ​​other layers provided on the same surface be within the aforementioned range. However, the ratio of the total area of ​​all layers does not necessarily have to be within the aforementioned range.

[0099] In a top view, it is preferable that the area of ​​the capacitive element be large. By increasing the area of ​​the capacitive element, the charge held in the capacitive element can be held for a long time. Therefore, it is preferable that the area of ​​the conductive layer 87, which functions as the lower electrode of the capacitive element, be large. The ratio of the total area of ​​the conductive layer 87, conductive layer 87A, conductive layer 87B, and dummy layer 87DM is particularly preferably 25% or more, more preferably 30% or more, and more preferably 40% or more. The same applies to the ratio of the total area of ​​the conductive layer 89, which functions as the upper electrode, and the layers provided on the same surface as the conductive layer 89.

[0100] The number, arrangement, and top surface shape of the conductive layer 87, conductive layer 87A, conductive layer 87B, and dummy layer 87DM are not limited to those shown in Figure 3A.

[0101] Figure 3B shows a top view of the resist mask during the formation of the conductive layer 87, conductive layer 87A, conductive layer 87B, and dummy layer 87DM shown in Figure 3A. The resist masks 97, 97A, 97B, and 97DM correspond to the conductive layer 87, 87A, 87B, and dummy layer 87DM, respectively. The resist masks 97, 97A, 97B, and 97DM are provided on the conductive film that will become the conductive layer 87, 87A, 87B, and dummy layer 87DM. In a top view, it is preferable that the ratio of the total area of ​​the resist masks 97, 97A, 97B, and 97DM to the area of ​​the pixel 230 be within the range described above. Similarly, it is preferable that the ratio of the total area of ​​the resist masks provided on the same surface for the other layers be within the range described above.

[0102] Figure 3B shows an example where the top surface shape of resist masks 97, 97A, 97B, and 97DM is rectangular, but the top surface shape is not particularly limited. Also, Figures 3A and 3B show an example where the top surface shape of the conductive layer and the corresponding resist mask are the same, but the present invention is not limited to this. The top surface shapes of the conductive layer and the resist mask may be different. For example, the edge of the conductive layer may be inside or outside the edge of the corresponding resist mask.

[0103] Similarly, for peripheral drive circuits, it is preferable that the ratio of the total area of ​​resist masks provided on the same surface is high. In a top view, it is preferable that the ratio of the total area of ​​resist masks provided on the same surface to the area of ​​peripheral drive circuits be within the aforementioned range. Also, in a top view, it is preferable that the ratio of the total area of ​​layers provided on the same surface to the area of ​​peripheral drive circuits be within the aforementioned range.

[0104] The foreign matter caused by the resist mask mentioned above can be suppressed from adhering to the processed film by, for example, changing the developer during the developer treatment. Alternatively, the adhesion of foreign matter to the processed film can be suppressed by extending the washing time after the developer treatment or by performing washing multiple times. For example, pure water can be used for washing. Pure water with added gas may also be used for washing. For example, pure water with added carbon dioxide, pure water with added hydrogen, or pure water with added nitrogen can be used. Alternatively, the adhesion of foreign matter to the processed film can be suppressed by blowing during drying after washing. For example, nitrogen, air, or noble gas can be used for blowing. Clean dry air (CDA) may also be used for blowing.

[0105] <Circuit Configuration Example 1> Figure 4 shows an example of a circuit configuration applicable to a semiconductor device according to one aspect of the present invention. The semiconductor device 100A shown in Figure 4 has a pixel circuit 51A and a light-emitting device 61.

[0106] One terminal of the light-emitting device 61 is electrically connected to the pixel circuit 51A, and the other terminal is electrically connected to the wiring 104. For example, one terminal of the light-emitting device 61 can be the anode terminal and the other terminal can be the cathode terminal. Alternatively, one terminal of the light-emitting device 61 can be the cathode terminal and the other terminal can be the anode terminal. The pixel circuit 51 has the function of controlling the light emission of the light-emitting device 61.

[0107] The pixel circuit 51A includes transistors M11 to M17 and capacitive elements C11 to C13.

[0108] In this specification, unless otherwise specified, transistors M11 to M17 are enhancement-type (normally-off type) n-channel field-effect transistors. Therefore, their threshold voltage (Vth) shall be greater than 0V.

[0109] One terminal of the light-emitting device 61 is electrically connected to either the source or drain of the transistor M15, and to one terminal of the capacitive element C13.

[0110] The gate of transistor M15 is electrically connected to the other terminal of capacitance element C13 and to one of the source or drain terminals of transistor M17. The other source or drain terminal of transistor M15 is electrically connected to one terminal of capacitance element C11, one terminal of capacitance element C12, one of the source or drain terminals of transistor M12, one of the source or drain terminals of transistor M13, and one of the source or drain terminals of transistor M16.

[0111] The gate of transistor M12 is electrically connected to the other terminal of the capacitive element C11, the other terminal of either the source or drain of transistor M13, and either the source or drain of transistor M11. Transistor M12 has a back gate. The back gate of transistor M12 is electrically connected to the other terminal of the capacitive element C12 and either the source or drain of transistor M14.

[0112] The source or drain of transistor M11 is electrically connected to wiring DL, and its gate is electrically connected to wiring GLa. Transistor M11 has the function of selecting whether to conduct or not conduct between the gate of transistor M12 and wiring DL.

[0113] The source or drain of transistor M12 is electrically connected to the wiring 101. Transistor M12 has a back gate. Transistor M12 has the function of controlling the amount of current Ie flowing through the light-emitting device 61. That is, transistor M12 has the function of controlling the amount of light emitted by the light-emitting device 61. Therefore, transistor M12 can be called a "driving transistor".

[0114] The gate of transistor M13 is electrically connected to the wiring GLB. Transistor M13 has the function of selecting whether to conduct or not conduct between the gate and source of transistor M12.

[0115] The gate of transistor M14 is electrically connected to wiring GLB, and the other end of either the source or drain is electrically connected to wiring 102. Transistor M14 has the function of selecting whether to conduct or not conduct between wiring 102 and one terminal of the capacitive element C12.

[0116] Transistor M15 has the function of switching between conduction and non-conductivity between transistor M12 and the light-emitting device 61. When transistor M15 is in the off state, the light-emitting device 61 is extinguished, and when transistor M15 is in the on state, the light-emitting device 61 can emit light. In order to reliably supply the amount of current determined by the drive transistor to the light-emitting device 61, transistor M15 must be reliably in the on state regardless of the values ​​of its source potential and drain potential.

[0117] The gate of transistor M16 is electrically connected to wiring GLa, and the other of its source or drain is electrically connected to wiring 103. Transistor M16 has the function of selecting whether to conduct or not conduct between one of the source or drain of transistor M12 and wiring 103.

[0118] The gate of transistor M17 is electrically connected to wiring GLa, and the other end of either the source or drain is electrically connected to wiring GLc. Transistor M17 has the function of selecting whether to conduct or not conduct between the gate of transistor M15 and wiring GLc.

[0119] The region where one terminal of capacitive element C11, one terminal of capacitive element C12, one source or drain of transistor M12, one source or drain of transistor M13, the other source or drain of transistor M15, and one source or drain of transistor M16 are electrically connected is also called node ND11.

[0120] The region where the other terminal of the capacitive element C12, the back gate of transistor M12, and either the source or drain of transistor M14 are electrically connected is also called node ND12.

[0121] The region where one source or drain of transistor M11, the other source or drain of transistor M13, the other terminal of capacitive element C11, and the gate of transistor M12 are electrically connected is also called node ND13.

[0122] The region where the gate of transistor M15, the other terminal of capacitance element C13, and either the source or drain of transistor M17 are electrically connected is also called node ND14.

[0123] Capacitor element C11 has the function of maintaining the potential difference between either the source or drain of transistor M12 and the gate of transistor M12 when node ND13 is floating. Capacitor element C12 has the function of maintaining the potential difference between either the source or drain of transistor M12 and the back gate of transistor M12 when node ND12 is floating. Capacitor element C13 has the function of maintaining the potential difference between either the source or drain of transistor M15 and the gate of transistor M15 when node ND14 is floating.

[0124] The capacitances of capacitive elements C11 to C13 are preferably large. In particular, the capacitances of capacitive elements C11 and C12 are preferably large, and preferably larger than the capacitance of capacitive element C13. The capacitances of capacitive elements C11 and C12 are preferably 2fF or more, more preferably 4fF or more, more preferably 6fF or more, more preferably 8fF or more, and more preferably 10fF or more. The capacitance of capacitive element C13 is preferably 1fF or more, more preferably 2fF or more, more preferably 3fF or more, more preferably 4fF or more, and more preferably 5fF or more. Since larger capacitances of capacitive elements C11 to C13 are preferable, there is no need to set an upper limit. However, if an upper limit is set, the capacitances of capacitive elements C11 and C12 should be 20fF or less, and the capacitance of capacitive element C13 should be 10fF or less.

[0125] By increasing the capacitance of capacitor element C11, the potential difference between either the source or drain of transistor M12 and the gate of transistor M12 can be maintained for a long period of time. By increasing the capacitance of capacitor element C12, the potential difference between either the source or drain of transistor M12 and the back gate of transistor M12 can be maintained for a long period of time. By increasing the capacitance of capacitor element C13, the potential difference between either the source or drain of transistor M15 and the gate of transistor M15 can be maintained for a long period of time.

[0126] Since the data held in capacitive elements C11 and C12 greatly affects the display quality, it is preferable that they be less affected by external noise. By increasing the capacitance of capacitive elements C11 and C12, the influence of external noise can be reduced, and a display device with high display quality can be realized. Furthermore, it is preferable that capacitive element C11 holds data for a longer period than one frame. Similarly, it is preferable that capacitive element C12 holds data for a longer period than one frame, more preferably for 1 second or more, more preferably for 1 minute or more, and more preferably for 1 hour or more. Therefore, the capacitance of capacitive element C12 may be larger than that of capacitive element C11. On the other hand, since it is sufficient for capacitive element C13 to hold a voltage that can sufficiently turn on transistor M15, its capacitance may be smaller than that of capacitive elements C11 and C12.

[0127] The capacitance of capacitive element C11 is preferably twice or more the capacitance of capacitive element C13, more preferably three times or more, more preferably four times or more, and more preferably five times or more. The capacitance of capacitive element C12 is preferably twice or more the capacitance of capacitive element C13, more preferably three times or more, more preferably four times or more, and more preferably five times or more.

[0128] In a top view, the area of ​​the capacitive element C11 is preferably at least twice the area of ​​the capacitive element C13, more preferably at least three times, more preferably at least four times, and more preferably at least five times. The area of ​​the capacitive element C12 is preferably at least twice the area of ​​the capacitive element C13, more preferably at least three times, more preferably at least four times, and more preferably at least five times.

[0129] In this specification, the area of ​​a capacitive element refers to the area of ​​the region where the upper electrode and lower electrode of the capacitive element overlap.

[0130] The structure of the transistor in a semiconductor device according to one aspect of the present invention is not particularly limited. The pixel circuit 51A can use transistors of various configurations, such as planar type, fin type, tri-gate type, top-gate type, bottom-gate type, and dual-gate type (structure in which gates are arranged above and below the channel). Furthermore, MOS type transistors, junction type transistors, bipolar transistors, etc., can be used as transistors according to one aspect of the present invention.

[0131] The semiconductor material to be applied to the transistor in a semiconductor device according to one aspect of the present invention is not particularly limited. For example, a transistor can be used in which a single-crystal semiconductor, polycrystalline semiconductor, microcrystalline semiconductor, or amorphous semiconductor is used in the region where the channel is formed (hereinafter referred to as the channel-forming region). Furthermore, it is not limited to elemental semiconductors whose main component is a single element (e.g., silicon (Si) or germanium (Ge)), but rather compound semiconductors (e.g., silicon germanium (SiGe) or gallium arsenide (GaAs)), or oxide semiconductors can be used.

[0132] In this embodiment, an example is shown in which a semiconductor device is constructed using n-channel transistors, but the present invention is not limited thereto. Some or all of the transistors constituting the semiconductor device may be p-channel transistors.

[0133] In one embodiment of the present invention, a semiconductor device may use a transistor containing an oxide semiconductor in the channel formation region (hereinafter referred to as an OS transistor). Alternatively, a transistor containing silicon in the channel formation region (hereinafter referred to as a Si transistor) may be used. Examples of silicon include single-crystal silicon, polycrystalline silicon, and amorphous silicon.

[0134] For example, an OS transistor may be used in the pixel circuit 51A. Since oxide semiconductors have a bandgap of 2eV or more, the off-current value of the OS transistor is extremely low.

[0135] At room temperature, the off-current value of an OS transistor per 1 μm channel width is 1 aA (1 × 10⁻¹⁶). -18 A) Below, 1zA(1×10 -21 A) Less than or equal to 1yA(1×10 -24 A) It can be less than or equal to the following. Note that the off-current value of a Si transistor per 1 μm of channel width at room temperature is 1 fA (1 × 10⁻¹⁰). -15 A) More than 1pA (1×10 -12 A) The answer is as follows. Therefore, it can be said that the off-current of an OS transistor is about 10 orders of magnitude lower than that of a Si transistor.

[0136] By using an OS transistor in the pixel circuit 51A, the charge written to the node can be retained for a long period of time. For example, when displaying a still image that does not require rewriting for each frame, it becomes possible to continue displaying the image even if the peripheral drive circuit stops operating. This method of stopping the operation of the peripheral drive circuit while a still image is being displayed is also called "idling stop driving." By performing idling stop driving, the power consumption of the display device can be reduced.

[0137] OS transistors exhibit almost no increase in off-current even in high-temperature environments. Specifically, the off-current hardly increases even at ambient temperatures between room temperature and 200°C. Furthermore, the on-current does not decrease significantly even in high-temperature environments. Semiconductor devices containing OS transistors operate stably and with high reliability even in high-temperature environments.

[0138] OS transistors have high dielectric strength between the source and drain. By using OS transistors in the pixel circuit 51A, stable operation is achieved even when the potential difference between potential Va and potential Vc is large, resulting in a highly reliable semiconductor device. In particular, it is preferable to use OS transistors for one or both of transistors M12 and M15.

[0139] The semiconductor layer of the OS transistor preferably contains, for example, indium, element M (where M is one or more selected from gallium, aluminum, silicon, boron, yttrium, tin, copper, vanadium, beryllium, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, and magnesium), and zinc. In particular, element M is preferably one or more selected from aluminum, gallium, yttrium, and tin.

[0140] In particular, it is preferable to use an oxide (also written as IGZO) containing indium (In), gallium (Ga), and zinc (Zn) for the semiconductor layer. Alternatively, the semiconductor layer may use an oxide (also written as IAZO) containing indium (In), aluminum (Al), and zinc (Zn). Alternatively, the semiconductor layer may use an oxide (also written as IAGZO) containing indium (In), aluminum (Al), gallium (Ga), and zinc (Zn).

[0141] When the semiconductor layer is an In-M-Zn oxide, it is preferable that the atomic ratio of In in the In-M-Zn oxide is greater than or equal to the atomic ratio of M. Examples of such atomic ratios of metal elements in an In-M-Zn oxide include: In:M:Zn=1:1:1 or near that composition, In:M:Zn=1:1:1.2 or near that composition, In:M:Zn=1:3:2 or near that composition, In:M:Zn=1:3:4 or near that composition, In:M:Zn=2:1:3 or near that composition, In:M:Zn=3:1:2 or near that composition, In:M:Zn=4: Examples of compositions include 2:3 or near 2:3, In:M:Zn=4:2:4.1 or near 4:1, In:M:Zn=5:1:3 or near 5:1:6, In:M:Zn=5:1:7 or near 5:1:7, In:M:Zn=5:1:8 or near 5:1:8, In:M:Zn=6:1:6 or near 6:1:6, and In:M:Zn=5:2:5 or near 5:1:7. Note that "near 5:1:8" includes a range of ±30% of the desired atomic ratio.

[0142] For example, when describing a composition with an atomic ratio of In:Ga:Zn = 4:2:3 or a similar ratio, it includes cases where, when the atomic ratio of In is 4, the atomic ratio of Ga is between 1 and 3, and the atomic ratio of Zn is between 2 and 4. Also, when describing a composition with an atomic ratio of In:Ga:Zn = 5:1:6 or a similar ratio, it includes cases where, when the atomic ratio of In is 5, the atomic ratio of Ga is greater than 0.1 and 2 or less, and the atomic ratio of Zn is between 5 and 7. Furthermore, when describing a composition with an atomic ratio of In:Ga:Zn = 1:1:1 or a similar ratio, it includes cases where, when the atomic ratio of In is 1, the atomic ratio of Ga is greater than 0.1 and 2 or less, and the atomic ratio of Zn is greater than 0.1 and 2 or less.

[0143] For example, a Si transistor may be used in the pixel circuit 51A. In particular, a transistor having low-temperature polysilicon (LTPS) in the channel formation region (hereinafter also referred to as an LTPS transistor) can be suitably used. LTPS transistors have high field-effect mobility and good frequency characteristics.

[0144] The pixel circuit 51A may be composed of multiple types of transistors using different semiconductor materials. For example, the pixel circuit 51A may be composed of LTPS transistors and OS transistors. A configuration combining LTPS transistors and OS transistors is sometimes referred to as LTPO.

[0145] When the pixel circuit 51A is composed of multiple types of transistors using different semiconductor materials, the transistors may be placed on different layers for each type of transistor. For example, if the pixel circuit 51A is composed of Si transistors and OS transistors, the layer containing the Si transistors and the layer containing the OS transistors may be stacked on top of each other. By using such a configuration, the area of ​​the pixel circuit 51A can be reduced.

[0146] The transistors constituting the peripheral drive circuit may be either Si transistors or OS transistors, or both. For example, OS transistors may be used for the transistors constituting the pixel circuit 51A, and Si transistors may be used for the transistors constituting the peripheral drive circuit. OS transistors have a low off-current, thus reducing power consumption. Also, Si transistors have a faster operating speed than OS transistors, making them suitable for use in peripheral drive circuits. Furthermore, depending on the display device, OS transistors may be used for both the transistors constituting the pixel circuit 51A and the transistors constituting the peripheral drive circuit. Alternatively, Si transistors may be used for both the transistors constituting the pixel circuit 51A and the transistors constituting the peripheral drive circuit.

[0147] Of the transistors constituting the pixel circuit 51A, transistors M11 and M13 to M17 each function as switches. Therefore, transistors M11 and M13 to M17 can be replaced with elements that can realize the function of a switch.

[0148] Figure 4 shows a configuration in which transistor M12 has a back gate and transistors other than transistor M12 do not have back gates, but the present invention is not limited to this. Transistors other than transistor M12 may also have back gates.

[0149] A multi-channel transistor may be used in the pixel circuit 51A. A multi-channel transistor has multiple electrically connected gates and multiple regions between the source and drain where the semiconductor layer and the gates overlap. In other words, a multi-channel transistor has multiple electrically connected gates and multiple channel-forming regions between the source and drain. In this specification, a multi-channel transistor may be referred to as a "multi-channel transistor," "multi-gate transistor," or "multi-gate type transistor."

[0150] As an example of a multi-channel transistor, Figure 5A shows an example of a circuit symbol for a double-gate type transistor 180A, which has two channel-forming regions between the source and drain.

[0151] Transistor 180A has a configuration in which transistors Tr1 and Tr2 are connected in series. Figure 5A shows a configuration in which one source or drain of transistor Tr1 is electrically connected to terminal S, the other source or drain of transistor Tr1 is electrically connected to one source or drain of transistor Tr2, and the other source or drain of transistor Tr2 is electrically connected to terminal D. In addition, the gates of transistors Tr1 and Tr2 are electrically connected and are also electrically connected to terminal G. Transistor 180A can also be said to have transistors Tr1 and Tr2 that share a common gate.

[0152] The transistor 180A shown in Figure 5A has the function of switching between conduction and non-conductivity between terminals S and D by changing the potential of terminal G. Therefore, the double-gate transistor 180A contains transistors Tr1 and Tr2 and functions as a single transistor. In other words, in Figure 5A, one of the source or drain of transistor 180A is electrically connected to terminal S, the other source or drain is electrically connected to terminal D, and the gate is electrically connected to terminal G.

[0153] A triple-gate transistor may be used in the pixel circuit 51A. Figure 5B shows an example of a circuit symbol for a triple-gate transistor 180B.

[0154] Transistor 180B has a configuration in which transistors Tr1, Tr2, and Tr3 are connected in series. Figure 5B shows a configuration in which one source or drain of transistor Tr1 is electrically connected to terminal S, the other source or drain of transistor Tr1 is electrically connected to one source or drain of transistor Tr2, the other source or drain of transistor Tr2 is electrically connected to one source or drain of transistor Tr3, and the other source or drain of transistor Tr3 is electrically connected to terminal D. In addition, the gates of transistors Tr1, Tr2, and Tr3 are electrically connected and are also electrically connected to terminal G.

[0155] The transistor 180B shown in Figure 5B has the function of switching between conduction and non-conductivity between terminals S and D by changing the potential of terminal G. Therefore, the triple-gate transistor 180B contains transistors Tr1, Tr2, and Tr3 and functions as a single transistor. In other words, in Figure 5B, one of the source or drain of transistor 180B is electrically connected to terminal S, the other source or drain is electrically connected to terminal D, and the gate is electrically connected to terminal G.

[0156] The transistors constituting the pixel circuit 51A may be configured with four or more transistors connected in series. The transistor 180C shown in Figure 5C consists of six transistors (transistors Tr1 to Tr6) connected in series. Furthermore, it shows a configuration in which the gates of the six transistors are electrically connected and also electrically connected to terminal G.

[0157] The transistor 180C shown in Figure 5C has the function of switching between conduction and non-conductivity between terminals S and D by changing the potential of terminal G. Therefore, transistor 180C contains transistors Tr1 to Tr6 and functions as a single transistor. In other words, in Figure 5C, one of the source or drain of transistor 180C is electrically connected to terminal S, the other source or drain is electrically connected to terminal D, and the gate is electrically connected to terminal G.

[0158] For example, when operating a transistor in the saturation region, the channel length of the transistor may be increased to improve its electrical characteristics in the saturation region. A multi-gate transistor may be used as a transistor with a long channel length.

[0159] Figures 5A to 5C show a configuration in which each transistor constituting the multi-gate transistor does not have a back gate, but the present invention is not limited to this. Each transistor constituting the multi-gate transistor may have a back gate.

[0160] <Configuration Example 2> Figure 6 shows an example of a configuration different from the semiconductor device 100A shown in Figure 4. The semiconductor device 100B shown in Figure 6 has a pixel circuit 51B and a light-emitting device 61. The semiconductor device 100B mainly differs from the semiconductor device 100A in that the transistors M11 and M13 to M17 in the pixel circuit 51B have back gates.

[0161] Figure 6 shows examples where the gate and back gate are electrically connected in transistor M11 and transistors M13 through M17. Note that the gate and back gate may not be electrically connected, and an arbitrary potential may be supplied to the back gate. The potential supplied to the back gate is not limited to a fixed potential. The potential supplied to the back gate of the transistors constituting the semiconductor device may differ or be the same for each transistor. Furthermore, it is not necessary to provide a back gate for all transistors constituting the semiconductor device. The semiconductor device may include transistors with back gates and transistors without back gates.

[0162] Figure 7 shows a top view illustrating an example configuration of the pixel circuit 51B shown in Figure 6. Figure 7 shows transistors M11 to M17 as an example. Some of the wiring constituting the pixel circuit 51B is also shown. Note that, to avoid complexity, some components of the pixel circuit 51B (such as insulating films) are omitted in Figure 7.

[0163] As shown in Figure 7, transistor M11 has a semiconductor layer 111A. Conductive layer 107A has a region that overlaps with conductive layer 103A via semiconductor layer 111A. Part of conductive layer 107A functions as the gate of transistor M11, and part of conductive layer 103A functions as the back gate of transistor M11.

[0164] Transistor M12 has a semiconductor layer 111B. Conductive layer 107B has a region that overlaps with conductive layer 103B via semiconductor layer 111B. Part of conductive layer 107B functions as the gate of transistor M11, and part of conductive layer 103B functions as the back gate of transistor M11. Figure 7 shows an example in which a triple-gate transistor is applied to transistor M12.

[0165] Transistor M13 has a semiconductor layer 111C. Conductive layer 107C has a region that overlaps with conductive layer 103C via semiconductor layer 111C. Part of conductive layer 107C functions as the gate of transistor M13, and part of conductive layer 103C functions as the back gate of transistor M13.

[0166] Transistor M14 has a semiconductor layer 111D. Conductive layer 107C has a region that overlaps with conductive layer 103C via semiconductor layer 111D. Part of conductive layer 107C functions as the gate of transistor M14, and part of conductive layer 103C functions as the back gate of transistor M14.

[0167] Transistor M15 has a semiconductor layer 111E. Conductive layer 107D has a region that overlaps with conductive layer 103D via semiconductor layer 111E. Part of conductive layer 107D functions as the gate of transistor M15, and part of conductive layer 103D functions as the back gate of transistor M15.

[0168] Transistor M16 has a semiconductor layer 111C. Conductive layer 107A has a region that overlaps with conductive layer 103A via semiconductor layer 111C. Part of conductive layer 107A functions as the gate of transistor M16, and part of conductive layer 103A functions as the back gate of transistor M16. Although Figure 7 shows a configuration in which transistors M16 and M13 share a portion of semiconductor layer 111C, the present invention is not limited to this. Transistors M16 and M13 may not share a semiconductor layer, and each transistor may have an isolated semiconductor layer.

[0169] Transistor M17 has a semiconductor layer 111F. Conductive layer 107A has a region that overlaps with conductive layer 103A via semiconductor layer 111F. Part of conductive layer 107A functions as the gate of transistor M17, and part of conductive layer 103A functions as the back gate of transistor M17.

[0170] The wiring 103 and conductive layers 103A to 103D can be made from the same material. Furthermore, the wiring 103 and conductive layers 103A to 103D can be formed using the same process. However, different materials may be used for the wiring 103 and conductive layers 103A to 103D.

[0171] The semiconductor layers 111A to 111F can be made of the same material. Furthermore, the semiconductor layers 111A to 111F can be formed using the same process. However, different materials may be used for the semiconductor layers 111A to 111F.

[0172] The conductive layers 107A to 107D can be made of the same material. Furthermore, the conductive layers 107A to 107D can be formed using the same process. However, different materials may be used for the conductive layers 107A to 107D.

[0173] The pixel circuit 51B preferably has one or more dummy transistors in addition to transistors M11 to M17. Figure 7 shows dummy transistors 109DMa and 109DMb, selected from among the multiple dummy transistors of the pixel circuit 51B, with reference numerals.

[0174] Dummy transistor 109DMa has a semiconductor layer 111DMa and a conductive layer 107DMa on the semiconductor layer 111DMa. Dummy transistor 109DMb has a semiconductor layer 111E and a conductive layer 107DMb on the semiconductor layer 111E.

[0175] A dummy transistor may have a layer in common with any of transistors M11 to M17. Figure 7 shows an example where dummy transistor 109DMb shares semiconductor layer 111E with transistor M15. A dummy transistor does not have to have a layer in common with any of transistors M11 to M17. The conductive layer 107DMa in dummy transistor 109DMa and the conductive layer 107DMb in dummy transistor 109DMb correspond to the gates of transistors M11 to M17, respectively. Conductive layers 107DMa and 107DMb can also be called dummy layers.

[0176] Figure 8 shows a top view of transistors M11 to M17, as shown in Figure 7, with capacitive elements C11 to C13 added. To avoid complexity, Figure 8 only shows the lower electrodes of capacitive elements C11 to C13. Some of the wiring constituting the pixel circuit 51B is also shown.

[0177] Capacitive elements C11 to C13 can be provided on transistors M11 to M17.

[0178] The conductive layer 105A, which functions as the lower electrode of the capacitive element C11, is electrically connected to either the source or drain of transistor M11 via the contact hole 110A. The conductive layer 105A is electrically connected to the gate of transistor M12 via the contact hole 110B. The conductive layer 105A is electrically connected to the other source or drain of transistor M13 via the contact hole 110C. The two electrically connected elements and wiring may also be electrically connected via plugs provided in the contact holes.

[0179] The conductive layer 105B, which functions as the lower electrode of the capacitive element C12, is electrically connected to the back gate of transistor M12 via the contact hole 110D. The conductive layer 105B is electrically connected to either the source or drain of transistor M14 via the contact hole 110E.

[0180] The conductive layer 105C, which functions as the lower electrode of the capacitive element C13, is electrically connected to the gate of transistor M15 via the contact hole 110F. The conductive layer 105C is electrically connected to the back gate of transistor M15 via the contact hole 110J. In other words, the gate and back gate of transistor M15 are electrically connected via the conductive layer 105C. The conductive layer 105C is electrically connected to either the source or drain of transistor M17 via the contact hole 110G.

[0181] As shown in Figure 8, it is preferable that the capacitive element C11 has a region that overlaps with the regions of transistors M11 and M13. It is preferable that the capacitive element C12 has a region that overlaps with the region of transistor M14. It is preferable that the capacitive element C13 has a region that overlaps with the region of transistor M17. By having capacitive elements have regions that overlap with transistors, the area of ​​the pixel circuit 51A can be reduced, and a high-definition display device can be made.

[0182] The conductive layer 105D is electrically connected to the other side of the source or drain of transistor M11 via the contact hole 110H.

[0183] The conductive layer 105E is electrically connected to either the source or drain of transistor M12 via the contact hole 110I. The conductive layer 105E is electrically connected to either the source or drain of transistor M15 via the contact hole 110K. The conductive layer 105E is electrically connected to either the source or drain of transistor M13 and either the source or drain of transistor M16 via the contact hole 110X.

[0184] The conductive layer 105F is electrically connected to the other side of the source or drain of transistor M12 via the contact hole 110L.

[0185] The conductive layer 105G is electrically connected to the other side of the source or drain of transistor M14 via the contact hole 110M.

[0186] The conductive layer 105H is electrically connected to either the source or drain of transistor M15 via the contact hole 110N.

[0187] The conductive layer 105I is electrically connected to the other side of the source or drain of transistor M16 via the contact hole 110P. The conductive layer 105I is electrically connected to the wiring 103 via the contact hole 110Q. In other words, the other side of the source or drain of transistor M16 is electrically connected to the wiring 103 via the conductive layer 105I. A conductive layer that electrically connects two elements and a wire, such as the conductive layer 105I that electrically connects transistor M16 and the wiring 103, can be called a wiring or simply a wire. For example, two transistors can be electrically connected by wiring.

[0188] The conductive layer 105J is electrically connected to the other side of the source or drain of transistor M17 via the contact hole 110R.

[0189] The conductive layer 105K is electrically connected to the conductive layer 103A via the contact hole 110S. The conductive layer 105K is electrically connected to the conductive layer 107A via the contact hole 110T. In other words, the gate and back gate of transistor M11, the gate and back gate of transistor M16, and the gate and back gate of transistor M17 are electrically connected via the conductive layer 105K.

[0190] The conductive layer 105L is electrically connected to the conductive layer 103C via the contact hole 110V. The conductive layer 105L is electrically connected to the conductive layer 107C via the contact hole 110W. In other words, the gate and back gate of transistor M13, and the gate and back gate of transistor M14 are electrically connected via the conductive layer 105L.

[0191] The conductive layers 105A to 105L can be made from the same material. Furthermore, the conductive layers 105A to 105L can be formed using the same process. However, different materials may be used for the conductive layers 105A to 105L.

[0192] Figure 9 shows a top view of the capacitive elements C11 to C13 shown in Figure 8, with the upper electrode added to the lower electrode.

[0193] The conductive layer 106A, which functions as the upper electrode of capacitive elements C11 and C12, has a region that overlaps with conductive layer 105A and a region that overlaps with conductive layer 105B. The conductive layer 106B, which functions as the upper electrode of capacitive element C13, has a region that overlaps with conductive layer 105C. Figure 9 shows an example in which the ends of the upper electrodes of capacitive elements C11 to C13 are located inward from the ends of the lower electrodes, that is, the upper electrodes enclose the lower electrodes. By configuring the upper electrodes to enclose the lower electrodes, leakage of the capacitive elements can be reduced. Note that the ends of the upper electrodes of capacitive elements C11 to C13 may be located outward from the ends of the lower electrodes.

[0194] The conductive layer 106A and conductive layer 106B can be made from the same material. Furthermore, the conductive layer 106A and conductive layer 106B can be formed using the same process. However, different materials may be used for conductive layer 106A and conductive layer 106B.

[0195] Each of the capacitive elements C11 to C13 is sandwiched between an upper electrode and a lower electrode and has an insulating layer that functions as a dielectric. Furthermore, the insulating layers of capacitive element C11, C12, and C13 can be formed in the same process.

[0196] The capacitances of capacitive elements C11 to C13 are preferably within the range described above. The area of ​​capacitive elements C11 to C13 in a top view is preferably within the range described above. As shown in Figure 9, when the upper electrode of a capacitive element includes the lower electrode, the area of ​​the capacitive element can be replaced with the area of ​​the lower electrode. That is, in a top view, the area of ​​the lower electrode of capacitive element C11 is preferably at least twice, more preferably at least three times, more preferably at least four times, and more preferably at least five times, the area of ​​the lower electrode of capacitive element C13. The area of ​​the lower electrode of capacitive element C12 is preferably at least twice, more preferably at least three times, more preferably at least four times, and more preferably at least five times, the area of ​​the lower electrode of capacitive element C13.

[0197] Figure 10 shows a top view of transistors M11 to M17 and capacitive elements C11 to C13 shown in Figure 9, with wiring GLa to GLc and wiring 101 added. Some of the wiring constituting the pixel circuit 51B is also shown.

[0198] The wiring GLa is electrically connected to the conductive layer 105K via the contact hole 115A. In other words, the wiring GLa is electrically connected to the gates of transistors M11, M16, and M17.

[0199] The wiring GLb is electrically connected to the conductive layer 105L via the contact hole 115B. In other words, the wiring GLb is electrically connected to the gates of transistor M13 and transistor M14.

[0200] The wiring GLc is electrically connected to the conductive layer 105J via the contact hole 115C. In other words, the wiring GLc is electrically connected to the other side of the source or drain of transistor M17.

[0201] Wiring 101 is electrically connected to the conductive layer 105F via the contact hole 115D. In other words, wiring 101 is electrically connected to the other side of the source or drain of transistor M12.

[0202] The conductive layer 113A is electrically connected to the conductive layer 105G via the contact hole 115E.

[0203] The conductive layer 113B is electrically connected to the conductive layer 105D via the contact hole 115F.

[0204] The conductive layer 113C is electrically connected to the conductive layer 106A via the contact hole 115G. The conductive layer 113C is electrically connected to the conductive layer 105E via the contact hole 115H. In other words, one terminal of the capacitive element C11, one terminal of the capacitive element C12, one source or drain of the transistor M12, one source or drain of the transistor M13, the other source or drain of the transistor M15, and one source or drain of the transistor M16 are electrically connected via the conductive layer 113C.

[0205] The conductive layer 113D is electrically connected to the conductive layer 105H via the contact hole 115I. The conductive layer 113D is electrically connected to the conductive layer 106B via the contact hole 115J. In other words, one terminal of the source or drain of the transistor M15 is electrically connected to one terminal of the capacitive element C13 via the conductive layer 113D.

[0206] The same material can be used for the wiring GLa to GLc, wiring 101, and conductive layers 113A to 113D. Furthermore, the same material can be used for the wiring GLa to GLc, wiring 101, and conductive layers 113A to 113D. However, different materials may be used for the wiring GLa to GLc, wiring 101, and conductive layers 113A to 113D.

[0207] Figure 11 shows a top view of the wiring GLa to GLc, wiring 101, and conductive layers 113A to 113D shown in Figure 10, with wiring DL and wiring 102 added. Some of the wiring constituting the pixel circuit 51B is also shown.

[0208] Wiring DL is electrically connected to the conductive layer 113B via contact hole 117A. In other words, wiring DL is electrically connected to the other side of the source or drain of transistor M11.

[0209] Wiring 102 is electrically connected to the conductive layer 113A via the contact hole 117B. In other words, wiring 102 is electrically connected to the other side of the source or drain of transistor M14.

[0210] The wiring 119 is electrically connected to the conductive layer 113D via the contact hole 117C.

[0211] In a top view, the ratio of the total area of ​​the layers provided on the same surface to the area of ​​the region where the pixel circuit 51B is provided is preferably 10% or more, more preferably 12% or more, more preferably 15% or more, more preferably 17% or more, more preferably 20% or more, more preferably 25% or more, more preferably 30% or more, and more preferably 40% or more. However, the ratio of the total area of ​​all layers does not have to be within the above range.

[0212] Let's explain in detail the ratio of the total area of ​​layers placed on the same surface.

[0213] Figure 12A shows a top view of the back gates of transistors M11 to M17, the back gate of the dummy transistor, wiring 103, and the wiring and dummy layer provided on the same plane. Figure 12A shows three pixel circuits 51B that are continuous in the row direction. In a top view, it is preferable that the ratio of the total area of ​​the back gates, wiring 103, wiring and dummy layer is high, and it is particularly preferable that it be within the range described above. In the example configuration shown in Figure 12A, the ratio of the total area of ​​the layers to the area of ​​the region where the pixel circuit 51 is provided is 34%.

[0214] Figure 12B shows a top view of the semiconductor layers of transistors M11 to M17, the semiconductor layer of the dummy transistor, and the semiconductor layers provided on the same surface. In the top view, it is preferable that the total area ratio of the semiconductor layers is high, and in particular, that it be within the range described above. In the example configuration shown in Figure 12B, the ratio of the total area of ​​the layers to the area of ​​the region where the pixel circuit 51 is provided is approximately 23%.

[0215] Figure 13A shows a top view of the gates of transistors M11 to M17, the gates of dummy transistors, and the wiring and dummy layers provided on the same plane. In the top view, it is preferable that the ratio of the total area of ​​the gates, wiring, and dummy layers is high, and it is particularly preferable that it be within the range described above. In the example configuration shown in Figure 13A, the ratio of the total area of ​​the layers to the area of ​​the region where the pixel circuit 51 is provided is approximately 21%.

[0216] Figure 13B shows a top view of the lower electrodes of capacitive elements C11 to C13, and the wiring provided on the same surface as them. In the top view, it is preferable that the total area ratio of the lower electrodes and wiring is high, and in particular, it is preferable that it be within the range described above. In the example configuration shown in Figure 13B, the ratio of the total area of ​​the layers to the area of ​​the region where the pixel circuit 51 is provided is approximately 58%.

[0217] Figure 14A shows a top view of the upper electrodes of the capacitive elements C11 to C13. In a top view, it is preferable that the total area of ​​the upper electrodes is high, and in particular, that it be within the range described above. In the example configuration shown in Figure 14A, the ratio of the total area of ​​the layers to the area of ​​the region where the pixel circuit 51 is provided is approximately 49%.

[0218] Figure 14B shows a top view of the wiring GLa to GLc, wiring 101, and the wiring provided on the same plane. In the top view, it is preferable that the proportion of the total area of ​​the wiring is high, and it is particularly preferable that it be within the range described above. In the example configuration shown in Figure 14B, the ratio of the total area of ​​the layers to the area of ​​the region where the pixel circuit 51 is provided is approximately 44%.

[0219] Figure 15A shows a top view of wiring DL, wiring 102, and wiring provided on the same plane as them. In a top view, it is preferable that the total area of ​​the wiring is high, and in particular, it is preferable that it be within the range described above. In the example configuration shown in Figure 15A, the ratio of the total area of ​​the layers to the area of ​​the region where the pixel circuit 51 is provided is approximately 43%.

[0220] Figure 15B shows a top view of the layers shown in Figures 12A to 15A superimposed. Although Figure 15B shows an excerpt of three pixel circuits 51B that are continuous in the row direction, as shown in Figure 1A, the display area 235 is provided with pixel circuits arranged in a matrix.

[0221] <Example of pixel arrangement> Let's explain the arrangement of pixels.

[0222] A pixel 230 having the function of emitting red light, a pixel 230 having the function of emitting green light, and a pixel 230 having the function of emitting blue light are combined and function as a single pixel, and full-color display can be achieved by controlling the amount of light emitted (luminescence) of each pixel 230. Therefore, each of the three pixels 230 functions as a sub-pixel. Each sub-pixel has a light-emitting device 61 and a pixel circuit 51 that controls the light emission of the light-emitting device 61.

[0223] The arrangement of subpixels is not particularly limited, and various arrangements can be used. Examples of arrangements for the light-emitting device 61 include stripe arrangements, S-stripe arrangements, matrix arrangements, delta arrangements, Bayer arrangements, and pentile arrangements.

[0224] Examples of sub-pixel arrangements are shown in Figures 16A to 16G. The top surface shape of the sub-pixels shown in Figures 16A to 16G corresponds to the top surface shape of the light-emitting region of the light-emitting device. Note that the top surface shape of the region where the pixel circuit 51 is provided and the top surface shape of the light-emitting region of the light-emitting device 61 controlled by the pixel circuit 51 do not have to be the same.

[0225] An example of a stripe array is shown in Figure 16A. The pixel 230 shown in Figure 16A has sub-pixels 230R that emit red light in the row direction, sub-pixels 230G that emit green light, and sub-pixels 230B that emit blue light.

[0226] Figure 16A shows an example where the top surface shape of the sub-pixel is rectangular, but the present invention is not limited to this. The top surface shape of the sub-pixel can be, for example, a triangle, a quadrilateral (including rectangles and squares), a pentagon or other polygon, a polygon with rounded corners, an ellipse, or a circle.

[0227] The colors of the light emitted from the three subpixels are not limited to a combination of red (R), green (G), and blue (B), but may also be cyan (C), magenta (M), and yellow (Y). The pixel 230 shown in Figure 16B has a subpixel 230C that emits cyan light in the row direction, a subpixel 230M that emits magenta light, and a subpixel 230Y that emits yellow light.

[0228] An example of a delta array is shown in Figure 16C. As shown in Figure 16C, the array may be arranged so that the lines connecting the center points of each subpixel form a triangle.

[0229] The area of ​​each sub-pixel may differ. If the luminous efficiency and reliability differ depending on the emission color, the area of ​​the sub-pixel may be changed for each emission color.

[0230] An example of an S-stripe array is shown in Figure 16D. Pixel 230 in Figure 16D is composed of two rows and two columns, with two subpixels (subpixels 230R and 230G) in the left column (column 1) and one subpixel (subpixel 230B) in the right column (column 2). In other words, pixel 230 has two subpixels (subpixels 230R and 230B) in the top row (column 1), two subpixels (subpixels 230G and 230B) in the bottom row (column 2), and subpixel 230B spans both rows.

[0231] The four subpixels may be combined and function as a single pixel 230. For example, as shown in Figure 16E, pixel 230 may have four subpixels: subpixel 230R, subpixel 230G, subpixel 230B, and subpixel 230W which has a light-emitting device 61 that emits white light. By adding subpixel 230W to subpixels 230R and 230G, the brightness of the display area of ​​pixel 230 can be increased. Alternatively, as shown in Figure 16F, subpixel 230Y may be added to subpixels 230R, 230G, and 230B. As shown in Figure 16G, subpixel 230W may be added to subpixels 230C, 230M, and 230Y.

[0232] 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.

[0233] 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).

[0234] By arranging 230 pixels in a 1920 x 1080 matrix, a display device 10 capable of full-color display at a resolution known as Full HD (also called "2K resolution," "2K1K," or "2K"). Furthermore, by arranging 230 pixels in a 3840 x 2160 matrix, a display device 10 capable of full-color display at a resolution known as Ultra HD (also called "4K resolution," "4K2K," or "4K"). Similarly, by arranging 230 pixels in a 7680 x 4320 matrix, a display device 10 capable of full-color display at a resolution known as Super Hi-Vision (also called "8K resolution," "8K4K," or "8K"). Increasing the number of pixels also makes it possible to realize a display device 10 capable of full-color display at a resolution of 16K or 32K.

[0235] The pixel density of the display area 235 is preferably 100 ppi or more and 10000 ppi or less, and more preferably 1000 ppi or more and 10000 ppi or less. For example, it may be 2000 ppi or more and 6000 ppi or less, or 3000 ppi or more and 5000 ppi or less.

[0236] There are no particular limitations on the aspect ratio of the display area 235. The display area 235 of the display device 10 can support various aspect ratios, such as 1:1 (square), 4:3, 16:9, and 16:10.

[0237] The diagonal size of the display area 235 may be between 0.1 inches and 100 inches, or it may be greater than 100 inches.

[0238] When the display device 10 is used as a display device for virtual reality (VR) or augmented reality (AR), the diagonal size of the display area 235 can be 0.1 inches or more and 5.0 inches or less, preferably 0.5 inches or more and 2.0 inches or less, and more preferably 1 inch or more and 1.7 inches or less. For example, the diagonal size of the display area 235 may be 1.5 inches or close to 1.5 inches. By setting the diagonal size of the display area 235 to 2.0 inches or less, preferably close to 1.5 inches, it becomes possible to process the display area in a single exposure process of the exposure apparatus (typically a scanner apparatus), thereby improving the productivity of the manufacturing process.

[0239] The configuration of the transistors used in the display area 235 may be appropriately selected according to the diagonal size of the display area 235. For example, when a single-crystal Si transistor is used in the display area 235, the diagonal size of the display area 235 is preferably 0.1 inches or more and 3 inches or less. When an LTPS transistor is used in the display area 235, the diagonal size of the display area 235 is preferably 0.1 inches or more and 30 inches or less, and more preferably 1 inch or more and 30 inches or less. When an LTPO (a configuration combining an LTPS transistor and an OS transistor) is used in the display area 235, the diagonal size of the display area 235 is preferably 0.1 inches or more and 50 inches or less, and more preferably 1 inch or more and 50 inches or less. When an OS transistor is used in the display area 235, the diagonal size of the display area 235 is preferably 0.1 inches or more and 200 inches or less, and more preferably 50 inches or more and 100 inches or less.

[0240] It is extremely difficult to increase the display area 235 of a single-crystal Si transistor beyond the size of the single-crystal Si substrate. Furthermore, LTPS transistors require laser crystallization equipment in their manufacturing process, making it difficult to accommodate larger displays (typically screen sizes exceeding 30 inches diagonally). On the other hand, OS transistors are not subject to the constraints of using laser crystallization equipment in their manufacturing process, or can be manufactured at relatively low process temperatures (typically below 450°C), allowing them to accommodate relatively large display panels (typically between 50 and 100 inches diagonally). Additionally, LTPO transistors can be applied to display panel sizes in the range between those using LTPS and OS transistors (typically between 1 and 50 inches diagonally).

[0241] Figure 17A shows a top view of the pixel circuit 51B shown in Figure 15B, with a conductive layer that functions as a pixel electrode for the light-emitting device 61 added. Note that, as shown in Figure 17A, the top surface shapes of the conductive layers 63A, 63B, and 63C that function as pixel electrodes do not have to match the top surface shape of the region having the pixel circuit 51B.

[0242] The conductive layer 63A is electrically connected to the wiring 119 shown in FIG. 11 through the contact hole 121A. That is, the conductive layer 63A that functions as a pixel electrode of the light-emitting device 61 is electrically connected to one of the source or drain of the transistor M15 and one terminal of the capacitor element C13. Similarly, the conductive layer 63B is electrically connected to one of the source or drain of the transistor M15 and one terminal of the capacitor element C13 through the contact hole 121B. The conductive layer 63C is electrically connected to one of the source or drain of the transistor M15 and one terminal of the capacitor element C13 through the contact hole 121C.

[0243] FIG. 17B shows a top view of the pixel electrode shown in FIG. 15B with the conductive layer 67 that functions as a common electrode of the light-emitting device 61 added. Note that FIG. 17B shows the structure below the conductive layer 67 through the hatching of the conductive layer 67 in order to clarify the structure.

[0244] By providing an EL layer (not shown) between the conductive layer 63A, the conductive layer 63B, and the conductive layer 63C that function as pixel electrodes and the conductive layer 67 that functions as a common electrode, the light-emitting device 61 can be formed on the pixel circuit 51B. FIG. 18A shows a configuration in which the light-emitting devices 61a, 61b, and 61c provided on the pixel circuit 51B are provided.

[0245] For example, a light-emitting device 61R can be formed by providing an EL layer that emits red light between conductive layer 63A and conductive layer 67. A light-emitting device 61G can be formed by providing an EL layer that emits green light between conductive layer 63B and conductive layer 67. A light-emitting device 61B can be formed by providing an EL layer that emits blue light between conductive layer 63C and conductive layer 67. Figure 18B shows a light-emitting device 61R having the function of emitting red light, a light-emitting device 61G having the function of emitting green light, and a light-emitting device 61B having the function of emitting blue light, which are provided on the pixel circuit 51B. The arrangement of the light-emitting devices 61 shown in Figure 18B corresponds to the S-stripe arrangement shown in Figure 16D.

[0246] <Example of operation> Next, an example of the operation of semiconductor device 100B will be described. Figure 19 is a timing chart illustrating an example of the operation of semiconductor device 100A. Figures 20 to 25 are circuit diagrams illustrating an example of the operation of semiconductor device 100A.

[0247] [Vth correction operation] First, a reset operation is performed during period T11. Specifically, a potential H is supplied to wiring GLa and wiring GLB, and a potential L is supplied to wiring GLC. As shown in Figure 20, transistors M11, M13, M14, M16, and M17 are turned ON.

[0248] Potential V0 is supplied to node ND11 via transistor M16. Furthermore, potential V0 is supplied to node ND13 via transistors M16 and M13. Potential V1 is supplied to node ND12 via transistor M14. Potential L is supplied to node ND14 via transistor M17. Therefore, transistor M15 is in the off state.

[0249] During period T11, wiring DL and wiring 103 become conductive via transistors M11, M13, and M16. Therefore, during period T11, it is preferable to have wiring DL and wiring 103 at the same potential, or to have wiring DL in a floating state.

[0250] Next, during period T12, a potential L is supplied to the wiring GLa. As shown in Figure 21, transistors M11, M16, and M17 are turned off.

[0251] Node ND14 is in a floating state, and the charge supplied to node ND14 is retained, thus maintaining the off state of transistor M15. Since the potential of node ND12 is V1, transistor M12 is in the ON state. Therefore, charge is supplied from wiring 101 to node ND11 via transistor M12, causing the potential of node ND11 to rise. Also, since transistor M13 is in the ON state, the potential of node ND13 also rises. Specifically, the potentials of nodes ND11 and ND13 rise to the value obtained by subtracting the Vth2 of transistor M12 from V1.

[0252] Here, since the potential of node ND12 is fixed at V1, as the potentials of nodes ND11 and ND13 rise, the potential difference between the back gate and the source of transistor M12 decreases. When the potential of node ND11 rises to near V1-Vth2, the current flowing from wiring 101 to node ND11 via transistor M12 decreases, and the rate at which the potential of node ND11 rises slows down. Therefore, the period T12 can ensure sufficient time for the potential of node ND11 to rise to V1-Vth2. Specifically, it is preferable to set the period T12 to 1 μs or more, and more preferably to 10 μs or more.

[0253] Next, during period T13, potential L is supplied to wiring GLb and potential H is supplied to wiring GLc. As shown in Figure 22, transistors M13 and M14 are turned off. Nodes ND11, ND12, and ND13 become floating, and the charge supplied to each node is retained. Also, the off state of transistor M15 is maintained.

[0254] [Data writing operation] During period T14, potential H is supplied to wiring GLa. As shown in Figure 23, transistor M11 turns on, and the video signal Vdata is supplied to node ND13. Also, transistor M16 turns on, and potential V0 is supplied to node ND11.

[0255] Since nodes ND11 and ND12 are capacitively coupled via the capacitive element C12, when the potential of node ND11 changes from V1-Vth2 to V0, the potential of node ND12 also changes accordingly. In this embodiment, since the potential V0 is 0V, the potential of node ND12 is expressed as V1-(V1-Vth2). That is, the potential of node ND12 becomes Vth2.

[0256] Transistor M17 turns on, and charge is supplied from the wiring GLc to node ND14. The potential of node ND14 rises to the value obtained by subtracting the Vth7 of transistor M17 from the potential H. For example, if the potential H is 6V, and the Vth5 of transistor M15 and the Vth7 of transistor M17 are both 1V, then the potential of node ND14 (H-Vth7) becomes 5V. Therefore, transistor M15 turns on, and the potential of the anode terminal of the light-emitting device 61 becomes V0.

[0257] [Light emission operation] During period T15, a potential L is supplied to the wiring GLa. As shown in Figure 24, transistors M11 and M16 are turned off. Current flows from wiring 101 to wiring 104, and the light-emitting device 61 emits light with a brightness corresponding to the current Ie. Also, the potential of node ND11 and the anode terminal of the light-emitting device 61 rises.

[0258] Node ND13 is floating, and nodes ND11 and ND13 are capacitively coupled via the capacitive element C11. During period T15, when the potential of node ND11 changes from V0 to Va1, the potential of node ND13 also changes accordingly. Here, the potential of node ND13 becomes the video signal Vdata + Va1. That is, even if the source potential of transistor M12 changes, the potential difference (voltage) between the gate and source of transistor M12 remains the same as the video signal Vdata.

[0259] Similarly, node ND12 is floating, and nodes ND11 and ND13 are capacitively coupled via the capacitive element C11. Therefore, the potential of node ND12 becomes Vth2 + Va1 in accordance with the potential change of node ND11. Thus, the potential difference between the back gate and the source of transistor M12 remains at Vth2.

[0260] Transistor M17 turns off, and node ND14 becomes floating. The anode terminal of the light-emitting device 61 and node ND14 are capacitively coupled via the capacitive element C13. Therefore, when the potential of the anode terminal of the light-emitting device 61 changes from V0 to potential Va2, the potential of node ND14 also changes accordingly. In this embodiment, since potential V0 is 0V, the potential of node ND14 becomes H-Vth7+Va2. That is, even if the potential of the anode terminal of the light-emitting device 61 changes, the potential difference (voltage) between the gate and source of transistor M15 remains at potential H-Vth7.

[0261] For example, when the gate of transistor M15 is at a fixed potential, if the source potential of transistor M15 rises, the potential difference between the gate of transistor M15 and the source of transistor M15 becomes smaller. When the potential difference between the gate of transistor M15 and the source of transistor M15 is lower than the threshold voltage of transistor M15, transistor M15 turns off. Therefore, when increasing the anode potential, it is necessary to supply a high potential to the gate of transistor M15 as well, and it is necessary to add a power supply or a power supply circuit for that purpose.

[0262] In the semiconductor device 100A according to one aspect of the present invention, by providing a capacitive element C13 between the gate of transistor M15 and the source of transistor M15 to form a bootstrap circuit, even when the anode potential is increased, the on-state of transistor M15 can be maintained without adding a power supply circuit. Therefore, current Ie can be stably supplied to the light-emitting device 61. Incidentally, the capacitive element C13 may be referred to as a "bootstrap capacitor". Also, each of the capacitive elements C11 and C12 also functions as a bootstrap capacitor.

[0263] The semiconductor device 100A according to one aspect of the present invention can be suitably used not only for a light-emitting device having a single structure but also for a light-emitting device having a tandem structure that requires a driving voltage larger than that of a light-emitting device having a single structure.

[0264] As described above, the amount of current Ie flowing through the light-emitting device 61 is determined by the video signal Vdata and the Vth2 of transistor M12. In the semiconductor device 100A according to one aspect of the present invention, by performing a Vth value correction operation, the amount of current Ie flowing through the light-emitting device 61 can be controlled by the video signal Vdata.

[0265] Since the luminescence brightness of the light-emitting device 61 is controlled by the video signal Vdata, it is necessary to ensure that transistor M15 is kept ON during light emission operation. In one aspect of the present invention, the semiconductor device 100A can be reliably kept ON during light emission operation. When the semiconductor device 100A according to one aspect of the present invention is used in a display device, accurate control of the current Ie becomes possible, thereby improving the reproduction of intermediate tones. Therefore, the display quality of the display device can be improved.

[0266] [Extinguishing operation] During period T16, a potential H is supplied to wiring GLa and a potential L is supplied to wiring GLc. As shown in Figure 25, transistors M11, M16, and M17 are turned ON, the potential at node ND11 becomes V0, and the potential at node ND14 becomes L. When the potential at node ND14 becomes L, transistor M15 is turned OFF, and the light emission of the light-emitting device 61 stops (extinguishes).

[0267] During period T16, a video signal for writing to another semiconductor device 100A electrically connected to wiring DL may be supplied to node ND13 via transistor M11, but since transistor M15 is in the off state, this does not interfere with the extinguishing operation. To distinguish it from the video signal Vdata during period T14 (data writing operation), it is labeled VdataX in Figure 25.

[0268] Display devices that use light-emitting devices such as EL elements as display elements can keep the light-emitting device lit for the duration of one frame. This driving method is also called "hold type" or "hold type drive." By using hold type drive for the display device, phenomena such as screen flicker can be reduced. On the other hand, with hold type drive, afterimages and image blurring are more likely to occur when displaying video. The resolution that a person perceives when displaying video is also called "video resolution." In other words, hold type drive tends to reduce video resolution.

[0269] A technique called "black insertion drive" is known to improve afterimages and image blurring in video playback. "Black insertion drive" is also called "pseudo-impulse drive" or "pseudo-impulse drive." Black insertion drive is a driving method that displays a black screen every other frame, or displays a black screen for a certain period within a frame.

[0270] The semiconductor device 100A can be suitably used not only for single-structure light-emitting devices but also for tandem-structure light-emitting devices that require a larger drive voltage than single-structure devices. Furthermore, the semiconductor device 100A can easily perform black insertion drive through extinguishing operation. A display device using the semiconductor device 100A according to one aspect of the present invention can achieve high-quality video display with less degradation of video resolution.

[0271] The configuration shown in this embodiment can be used in appropriate combination with the configurations shown in other embodiments and examples.

[0272] (Embodiment 2) This embodiment describes a light-emitting device that can be used in a semiconductor device according to one aspect of the present invention.

[0273] <Example of light-emitting device configuration> As shown in Figure 26A, the light-emitting device 61 includes an EL layer 172 between a pair of electrodes (conductive layer 171, conductive layer 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).

[0274] A configuration comprising 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 26A is referred to as a single structure.

[0275] Figure 26B shows a modified example of the EL layer 172 of the light-emitting device 61 shown in Figure 26A. Specifically, the light-emitting device 61 shown in Figure 26B includes a layer 4430-1 on the conductive layer 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 a conductive layer 173 on layer 4420-2. For example, when the conductive layer 171 is the anode and the conductive layer 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, if conductive layer 171 is used as the cathode and conductive layer 173 as 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. With such a layer structure, it is possible to efficiently inject carriers into the light-emitting layer 4411 and improve the efficiency of carrier recombination within the light-emitting layer 4411.

[0276] As shown in Figure 26C, a configuration in which multiple light-emitting layers (light-emitting layer 4411, light-emitting layer 4412, light-emitting layer 4413) are provided between layer 4420 and layer 4430 is also an example of a single structure.

[0277] As shown in Figure 26D, 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. A tandem structure enables the realization of a light-emitting device capable of high-brightness emission.

[0278] When applying the tandem structure shown in Figure 26D to the light-emitting device 61, the light-emitting colors of 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. Furthermore, if the display area 235 includes three sub-pixels R, G, and B, and each sub-pixel is equipped with a light-emitting device, a tandem structure may be applied to the light-emitting device of each sub-pixel. Specifically, the EL layers 172a and 172b of the R sub-pixel each have a material capable of emitting red light, the EL layers 172a and 172b of the G sub-pixel each have a material capable of emitting green light, and the EL layers 172a and 172b of the B sub-pixel each have a material capable of emitting blue light. In other words, the materials of light-emitting layer 4411 and 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 device 61 can be improved.

[0279] The light-emitting color of the light-emitting device 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 device.

[0280] 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). A light-emitting device that emits white light preferably has a configuration in which the light-emitting layer contains two or more types of light-emitting materials. To obtain white light emission, two light-emitting materials should be selected such that the light emitted by each material 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. Furthermore, in the case of a light-emitting device having three or more light-emitting layers, a configuration that emits white light can be achieved by mixing the respective light-emitting colors.

[0281] 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.

[0282] <Method for forming light-emitting devices> The following describes an example of a method for forming the light-emitting device 61.

[0283] Figure 27A shows a schematic top view of the light-emitting device 61. The light-emitting device 61 has multiple red light-emitting devices 61R, multiple green light-emitting devices 61G, and multiple blue light-emitting devices 61B. In Figure 27A, the labels R, G, and B are added within the light-emitting area of ​​each light-emitting device for easy distinction. The configuration of the light-emitting device 61 shown in Figure 27A may also be called an SBS (Side By Side) structure. Furthermore, Figure 27A illustrates a configuration with three light-emitting colors: red (R), green (G), and blue (B), but is not limited to this. For example, a configuration with four or more colors is also possible.

[0284] Light-emitting devices 61R, 61G, and 61B are each arranged in a matrix. Figure 27A shows a so-called stripe arrangement in which light-emitting devices of the same color are arranged in one direction, but the arrangement method of the light-emitting devices is not limited to this. As an arrangement method for the light-emitting devices, delta arrangement, zigzag arrangement, S-Stripe RGB arrangement, or pentile arrangement can be used.

[0285] Figure 27B is a schematic cross-sectional view corresponding to the dashed line A1-A2 in Figure 27A. Figure 27B shows cross-sections of light-emitting devices 61R, 61G, and 61B. Light-emitting devices 61R, 61G, and 61B are each provided on an insulating layer 363 and have a conductive layer 171 that functions as a pixel electrode and a conductive layer 173 that functions as a common electrode. The insulating layer 363 can be an inorganic insulating film or an organic insulating film, or both. It is preferable to use an inorganic insulating film as the insulating layer 363. Examples of inorganic insulating films include oxide insulating films and nitride insulating films such as silicon oxide film, silicon oxide nitride film, silicon nitride film, silicon nitride film, aluminum oxide film, aluminum oxide nitride film, and hafnium oxide film.

[0286] The light-emitting device 61R has an EL layer 172R between a conductive layer 171 that functions as a pixel electrode and a conductive layer 173 that functions as a common electrode. The EL layer 172R has a luminescent organic compound that emits light with intensity in at least the red wavelength range. The EL layer 172G of the light-emitting device 61G has a luminescent organic compound that emits light with intensity in at least the green wavelength range. The EL layer 172B of the light-emitting device 61B has a luminescent organic compound that emits light with intensity in at least the blue wavelength range.

[0287] Each of the EL layers 172R, 172G, and 172B may have, in addition to a layer containing a light-emitting organic compound (light-emitting layer), one or more of the following: an electron injection layer, an electron transport layer, a hole injection layer, and a hole transport layer.

[0288] A conductive layer 171, which functions as a pixel electrode, is provided for each light-emitting device. A conductive layer 173, which functions as a common electrode, is provided as a continuous layer common to each light-emitting device. A conductive film that is transparent to visible light is used for either the conductive layer 171 that functions as a pixel electrode or the conductive layer 173 that functions as a common electrode, and a conductive film that is reflective is used for the other. By making the conductive layer 171 that functions as a pixel electrode transparent and the conductive layer 173 that functions as a common electrode reflective, a bottom-emission type display device can be made. Conversely, by making the conductive layer 171 that functions as a pixel electrode reflective and the conductive layer 173 that functions as a common electrode transparent, a top-emission type display device can be made. Furthermore, by making both the conductive layer 171 that functions as a pixel electrode and the conductive layer 173 that functions as a common electrode transparent, a dual-emission type display device can also be made.

[0289] For example, if the light-emitting device 61R is a top-emission type, the light 175R emitted from the light-emitting device 61R is emitted towards the conductive layer 173. If the light-emitting device 61R is a top-emission type, the light 175G emitted from the light-emitting device 61G is emitted towards the conductive layer 173. If the light-emitting device 61B is a top-emission type, the light 175B emitted from the light-emitting device 61B is emitted towards the conductive layer 173.

[0290] An insulating layer 272 is provided to cover the edges of the conductive layer 171, which functions as a pixel electrode. The edges of the insulating layer 272 are preferably tapered. The insulating layer 272 can be made of the same material as that used for the insulating layer 363.

[0291] The insulating layer 272 is provided to prevent adjacent light-emitting devices 61 from unintentionally short-circuiting and causing false light emission. It also serves to prevent the metal mask from contacting the conductive layer 171 when a metal mask is used to form the EL layer 172.

[0292] Each of the EL layers 172R, 172G, and 172B has a region in contact with the upper surface of the conductive layer 171, which functions as a pixel electrode, and a region in contact with the surface of the insulating layer 272. The edges of the EL layers 172R, 172G, and 172B are located on the insulating layer 272.

[0293] As shown in Figure 27B, a gap is provided between the two EL layers in light-emitting devices of different colors. It is preferable that the EL layers 172R, 172G, and 172G are arranged so that they do not touch each other. This effectively prevents current from flowing through two adjacent EL layers, which can cause unintended light emission (also known as crosstalk). Therefore, contrast can be enhanced, and a display device with high display quality can be realized.

[0294] EL layer 172R, EL layer 172G, and EL layer 172G can be fabricated separately using methods such as vacuum deposition with a shadow mask like a metal mask. Alternatively, they may be fabricated separately using photolithography. By using photolithography, it is possible to realize a display device with high resolution that is difficult to achieve when using a metal mask.

[0295] 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. Furthermore, in this specification, devices fabricated without using a metal mask or FMM may be referred to as MML (Metal Maskless) structured devices. Because MML structured display devices are fabricated without a metal mask, they offer greater design flexibility in terms of pixel arrangement and pixel shape compared to MM structured display devices.

[0296] A protective layer 271 is provided on the conductive layer 173, which functions as a common electrode, covering the light-emitting devices 61R, 61G, and 61B. The protective layer 271 has the function of preventing impurities such as water from diffusing to each light-emitting device from above.

[0297] The protective layer 271 can be, for example, a single-layer structure or a multilayer structure including at least an inorganic insulating film. Examples of inorganic insulating films include oxide films or nitride films such as silicon oxide film, silicon oxide nitride film, silicon nitride film, silicon nitride film, aluminum oxide film, aluminum oxide nitride film, and hafnium oxide film. Alternatively, semiconductor materials such as indium gallium oxide and indium gallium zinc oxide (IGZO) may be used as the protective layer 271. The protective layer 271 may be formed using one or more of the ALD method, CVD method, and sputtering method. Although a configuration including an inorganic insulating film as the protective layer 271 has been exemplified, it is not limited to this. For example, the protective layer 271 may be a multilayer structure of an inorganic insulating film and an organic insulating film.

[0298] 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).

[0299] When indium gallium zinc oxide is used as the protective layer 271, it can be processed using either a wet etching method or a dry etching method. For example, when IGZO is used as the protective layer 271, chemicals such as oxalic acid, phosphoric acid, or a mixed chemical solution (for example, a mixed chemical solution of phosphoric acid, acetic acid, nitric acid, and water (also called a mixed aluminum etchant)) can be used. The mixed aluminum etchant can be formulated in a volume ratio of approximately phosphoric acid:acetic acid:nitric acid:water = 53.3:6.7:3.3:36.7.

[0300] Figure 27C shows a different example from the one described above. Specifically, Figure 27C has a light-emitting device 61W that emits white light. The light-emitting device 61W has an EL layer 172W that emits white light between a conductive layer 171 that functions as a pixel electrode and a conductive layer 173 that functions as a common electrode.

[0301] The EL layer 172W can be configured, for example, by stacking two light-emitting layers selected so that their emitted colors are complementary. Alternatively, a stacked EL layer with a charge-generating layer sandwiched between the light-emitting layers may be used. When three or more light-emitting layers are stacked, a configuration that emits white light can be achieved by mixing the emitted colors of each layer.

[0302] Figure 27C shows three light-emitting devices 61W side by side. The left light-emitting device 61W has a colored layer 264R on its top. The colored layer 264R functions as a bandpass filter that transmits red light. Similarly, the center light-emitting device 61W has a colored layer 264G that transmits green light on its top, and the right light-emitting device 61W has a colored layer 264B that transmits blue light on its top. This allows the display device to display a color image.

[0303] Here, the EL layer 172W and the conductive layer 173, which functions as a common electrode, are separated between two adjacent light-emitting devices 61W. This prevents current from flowing through the EL layer 172W between the two adjacent light-emitting devices 61W, thus preventing unintended light emission. In particular, when a stacked EL layer with a charge generation layer between the two light-emitting layers is used as the EL layer 172W, the effect of crosstalk becomes more pronounced as the resolution increases, i.e., the distance between adjacent pixels decreases, resulting in a decrease in contrast. Therefore, this configuration makes it possible to realize a display device that combines high resolution and high contrast.

[0304] The separation of the EL layer 172W and the conductive layer 173, which functions as a common electrode, is preferably performed by photolithography. This allows for a reduction in the spacing between light-emitting devices, thereby enabling the realization of a display device with a higher aperture ratio compared to cases where a shadow mask such as a metal mask is used.

[0305] In the case of a bottom-emission type light-emitting device, a colored layer can be provided between the conductive layer 171, which functions as a pixel electrode, and the insulating layer 363.

[0306] Figure 27D shows a different example from the above. Specifically, Figure 27D shows a configuration in which the insulating layer 272 is not provided between the light-emitting devices 61R, 61G, and 61B. This configuration makes it possible to create a display device with a high aperture ratio. In addition, by not providing the insulating layer 272, the unevenness of the light-emitting device 61 is reduced, thus improving the viewing angle of the display device. Specifically, the viewing angle can be made 150° or more and less than 180°, preferably 160° or more and less than 180°, and more preferably 160° or more and less than 180°.

[0307] The protective layer 271 covers the sides of the EL layers 172R, 172G, and 172B. This configuration suppresses impurities (typically water, etc.) that could enter from the sides of the EL layers 172R, 172G, and 172B. In addition, the leakage current between adjacent light-emitting devices 61 is reduced, resulting in improved saturation and contrast ratio, and reduced power consumption.

[0308] In the configuration shown in Figure 27D, the top surfaces of the conductive layer 171, the EL layer 172R, and the conductive layer 173 are roughly identical. Such a structure can be formed all at once using a resist mask or the like after the conductive layer 171, the EL layer 172R, and the conductive layer 173 have been formed. This process can also be called self-aligned patterning, as it involves processing the EL layer 172R and the conductive layer 173 using the conductive layer 173 as a mask. Although the EL layer 172R has been described here, the same configuration can be applied to the EL layer 172G and the EL layer 172B.

[0309] In Figure 27D, a protective layer 273 is provided on top of the protective layer 271. For example, by forming the protective layer 271 using an apparatus capable of forming a highly covering film (typically an ALD apparatus, etc.) and forming the protective layer 273 using an apparatus capable of forming a film with lower covering properties than the protective layer 271 (typically a sputtering apparatus, etc.), a region 275 can be provided between the protective layer 271 and the protective layer 273. In other words, the region 275 is located between the EL layer 172R and the EL layer 172G, and between the EL layer 172G and the EL layer 172B.

[0310] Region 275 contains one or more elements selected from, for example, air, nitrogen, oxygen, carbon dioxide, and Group 18 elements (typically helium, neon, argon, xenon, krypton, etc.). Region 275 may also contain gases used during the deposition of the protective layer 273. For example, when the protective layer 273 is deposited by sputtering, region 275 may contain one or more of the above-mentioned Group 18 elements. If region 275 contains gases, the gases can be identified by gas chromatography or other methods. Alternatively, when the protective layer 273 is deposited by sputtering, the protective layer 273 may also contain gases used during sputtering. In this case, elements such as argon may be detected when the protective layer 273 is analyzed by energy-dispersive X-ray spectroscopy (EDX analysis).

[0311] If the refractive index of region 275 is lower than that of the protective layer 271, light emitted from EL layer 172R, EL layer 172G, or EL layer 172B is reflected at the interface between the protective layer 271 and region 275. This can suppress the incidence of light emitted from EL layer 172R, EL layer 172G, or EL layer 172B onto adjacent pixels. This suppresses the mixing of different emission colors from neighboring pixels, thereby improving the display quality of the display device.

[0312] In the configuration shown in Figure 27D, the region between light-emitting device 61R and light-emitting device 61G, or the region between light-emitting device 61G and light-emitting device 61B (hereinafter simply referred to as the distance between light-emitting devices) can be narrowed. Specifically, the distance between light-emitting devices can be 1 μm or less, preferably 500 nm or less, and more preferably 200 nm or less, 100 nm or less, 90 nm or less, 70 nm or less, 50 nm or less, 30 nm or less, 20 nm or less, 15 nm or less, or 10 nm or less. In other words, the distance between the side surface of EL layer 172R and the side surface of EL layer 172G, or the distance between the side surface of EL layer 172G and the side surface of EL layer 172B, has a region of 1 μm or less, preferably a region of 0.5 μm (500 nm) or less, and more preferably a region of 100 nm or less.

[0313] For example, if region 275 contains a gas, it is possible to isolate the light-emitting devices while suppressing color mixing or crosstalk of light from each light-emitting device.

[0314] Region 275 may be filled with a filler. Examples of fillers 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 a filler. The photoresist used as a filler may be a positive-type photoresist or a negative-type photoresist.

[0315] 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 an SBS structure light-emitting device. 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.

[0316] Figure 28A shows a different example from the one described above. Specifically, the configuration shown in Figure 28A differs from the configuration shown in Figure 27D in the configuration of the insulating layer 363. When the light-emitting devices 61R, 61G, and 61B are processed, a portion of the upper surface of the insulating layer 363 is removed, creating a recess. A protective layer 271 is formed in this recess. In other words, in a cross-sectional view, the lower surface of the protective layer 271 is located lower than the lower surface of the conductive layer 171 in a certain region. Having this region effectively suppresses impurities (typically water, etc.) that could enter the light-emitting devices 61R, 61G, and 61B from below. The above-mentioned recess may be formed when impurities (also called residues) that may adhere to the sides of each light-emitting device during processing of the light-emitting devices 61R, 61G, and 61B are removed by wet etching or the like. After removing the above-mentioned residue, a highly reliable display device can be created by covering the sides of each light-emitting device with a protective layer 271.

[0317] Figure 28B shows a different example from the above. Specifically, the configuration shown in Figure 28B includes an insulating layer 276 and a microlens array 277 in addition to the configuration shown in Figure 28A. The insulating layer 276 functions as an adhesive layer. When the refractive index of the insulating layer 276 is lower than that of the microlens array 277, the microlens array 277 can concentrate the light emitted from the light-emitting devices 61R, 61G, and 61B. This can improve the light extraction efficiency of the display device. This is particularly preferable when the user views the display surface from the front of the display surface of the display device, as it allows for the viewing of a bright image. Various types of curing adhesives can be used as the insulating layer 276, 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.

[0318] Figure 28C shows a different example from the one described above. Specifically, the configuration shown in Figure 28C has three light-emitting devices 61W instead of the light-emitting devices 61R, 61G, and 61B in the configuration shown in Figure 28A. In addition, there is an insulating layer 276 above the three light-emitting devices 61W, and above the insulating layer 276 there are colored layers 264R, 264G, and 264B. Specifically, a colored layer 264R that transmits red light is provided in the position overlapping with the left light-emitting device 61W, a colored layer 264G that transmits green light is provided in the position overlapping with the central light-emitting device 61W, and a colored layer 264B that transmits blue light is provided in the position overlapping with the right light-emitting device 61W. As a result, the semiconductor device can display a color image. The configuration shown in Figure 28C is also a modified version of the configuration shown in Figure 27C.

[0319] Figure 28D shows a different example from the one described above. Specifically, in the configuration shown in Figure 28D, the protective layer 271 is provided adjacent to the sides of the conductive layer 171 and the EL layer 172. The conductive layer 173 is provided as a continuous layer common to each light-emitting device. In addition, in the configuration shown in Figure 28D, it is preferable that region 275 is filled with a filler material.

[0320] By adding a microcavity structure to the light-emitting device 61, the color purity of the emitted light can be improved. To add a microcavity structure to the light-emitting device 61, the product of the distance d between the conductive layer 171 and the conductive layer 173 and the refractive index n of the EL layer 172 (optical distance) should be configured such that it is m times half the wavelength λ (where m is an integer greater than or equal to 1). The distance d can be calculated using Equation 1.

[0321] d = m × λ / (2 × n) ... Equation 1.

[0322] According to Equation 1, the distance d of the light-emitting device 61 with a microcavity structure is determined according to the wavelength (emission color) of the emitted light. The distance d corresponds to the thickness of the EL layer 172. Therefore, the EL layer 172G may be made thicker than the EL layer 172B, and the EL layer 172R may be made thicker than the EL layer 172G.

[0323] Preferably, one of the pair of electrodes in the light-emitting device 61 is a semitransmitting / semi-reflective electrode that is transparent to and reflective of visible light, and the other is a reflective electrode that is reflective of visible light. More precisely, distance d is the distance from the reflective region of the conductive layer 171 that functions as a reflective electrode to the reflective region of the conductive layer 173 that functions as a semitransmitting / semi-reflective electrode. For example, if the conductive layer 171 has a laminated structure of silver and indium tin oxide (hereinafter also referred to as ITO), which is a transparent conductive film, and the ITO is on the EL layer 172 side, the distance d according to the emission color can be set by adjusting the film thickness of the ITO. That is, even if the thicknesses of EL layer 172R, EL layer 172G, and EL layer 172B are the same, a distance d suitable for the emission color can be obtained by changing the thickness of the ITO.

[0324] However, it can be difficult to precisely determine the location of the reflective regions in conductive layers 171 and 173. In this case, it is assumed that the effect of the microcavity can be sufficiently obtained by assuming that any location in conductive layers 171 and 173 is a reflective region.

[0325] The light-emitting device 61 is composed of a hole injection layer, a hole transport layer, a light-emitting layer, an electron transport layer, an electron injection layer, and the like. Detailed configuration examples of the light-emitting device 61 will be described in other embodiments. In order to improve the light extraction efficiency in the microcavity structure, it is preferable to make the optical distance from the conductive layer 171, which functions as a reflective electrode, to the light-emitting layer an odd multiple of λ / 4. To achieve this optical distance, it is preferable to appropriately adjust the thickness of each layer constituting the light-emitting device 61.

[0326] When light is emitted from the conductive layer 173 side, it is preferable that the reflectance of the conductive layer 173 is greater than its transmittance. Preferably, the light transmittance of the conductive layer 173 should be 2% to 50%, more preferably 2% to 30%, and even more preferably 2% to 10%. By reducing the transmittance (increasing the reflectance) of the conductive layer 173, the effect of the microcavity can be enhanced.

[0327] Figure 29A shows a different example from the one described above. Specifically, in the configuration shown in Figure 29A, the EL layer 172 extends beyond the edge of the conductive layer 171 in each of the light-emitting devices 61R, 61G, and 61B. For example, in light-emitting device 61R, the EL layer 172R extends beyond the edge of the conductive layer 171. Also, in light-emitting device 61G, the EL layer 172G extends beyond the edge of the conductive layer 171. In light-emitting device 61B, the EL layer 172B extends beyond the edge of the conductive layer 171.

[0328] In each of the light-emitting devices 61R, 61G, and 61B, the EL layer 172 and the protective layer 271 have overlapping regions via the insulating layer 270. In addition, an insulating layer 278 is provided on top of the protective layer 271 in the region between adjacent light-emitting devices 61.

[0329] Examples of insulating layer 278 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 the insulating layer 278. The photoresist used as the insulating layer 278 may be a positive-type photoresist or a negative-type photoresist.

[0330] A common layer 174 is provided on the light-emitting devices 61R, 61G, 61B, and the insulating layer 278, and a conductive layer 173 is provided on the common layer 174. The common layer 174 has a region in contact with the EL layer 172R, a region in contact with the EL layer 172G, and a region in contact with the EL layer 172B. The common layer 174 is shared by the light-emitting devices 61R, 61G, and 61B.

[0331] The common layer 174 can be one or more of the following: a hole injection layer, a hole transport layer, a hole blocking layer, an electron blocking layer, an electron transport layer, and an electron injection layer. For example, the common layer 174 may be a carrier injection layer (a hole injection layer or an electron injection layer). The common layer 174 can also be considered a part of the EL layer 172. The common layer 174 may be provided only as needed. If the common layer 174 is provided, it is not necessary to provide any layers in the EL layer 172 that have the same function as the common layer 174.

[0332] A protective layer 273 is provided on the conductive layer 173, and an insulating layer 276 is provided on the protective layer 273.

[0333] Figure 29B shows a different example from the one described above. Specifically, the configuration shown in Figure 29B has three light-emitting devices 61W instead of the light-emitting devices 61R, 61G, and 61B in the configuration shown in Figure 29A. In addition, there is an insulating layer 276 above the three light-emitting devices 61W, and above the insulating layer 276 there are colored layers 264R, 264G, and 264B. Specifically, a colored layer 264R that transmits red light is provided in the position overlapping with the left light-emitting device 61W, a colored layer 264G that transmits green light is provided in the position overlapping with the central light-emitting device 61W, and a colored layer 264B that transmits blue light is provided in the position overlapping with the right light-emitting device 61W. As a result, the semiconductor device can display a color image. The configuration shown in Figure 29B is also a modified version of the configuration shown in Figure 28C.

[0334] Some of the transistors constituting the functional circuit of layer 40 may be provided in layer 50. Similarly, some of the transistors constituting the pixel circuit 51 of layer 50 may be provided in layer 40. Therefore, the functional circuit may include Si transistors and OS transistors. Furthermore, the pixel circuit 51 may include Si transistors and OS transistors.

[0335] Figure 30 shows an example of a partial cross-sectional configuration of the display device 10 shown in Figure 1A. The display device 10 shown in Figure 30 comprises a substrate 301, a layer 50 including a capacitive element 246 and a transistor 310, and a layer 60 including light-emitting devices 61R, 61G, and 61B. The layer 60 is provided on the insulating layer 363 of the layer 50.

[0336] The transistor 310 is a transistor having a channel-forming region in the substrate 301. The substrate 301 can be a semiconductor substrate such as a single-crystal silicon substrate. The transistor 310 comprises a portion of the substrate 301, a conductive layer 311, a low-resistance region 312, an insulating layer 313, and an insulating layer 314. The conductive layer 311 functions as a gate electrode. The insulating layer 313 is located between the substrate 301 and the conductive layer 311 and functions as a gate insulating layer. The low-resistance region 312 is a region of the substrate 301 doped with impurities and functions as either a source or a drain. The insulating layer 314 is provided covering the side surface of the conductive layer 311.

[0337] An element isolation layer 315 is provided between two adjacent transistors 310 so as to be embedded in the substrate 301.

[0338] An insulating layer 261 is provided covering the transistor 310, and a capacitive element 246 is provided on the insulating layer 261.

[0339] The capacitive element 246 comprises a conductive layer 241, a conductive layer 245, and an insulating layer 243 located between them. The conductive layer 241 functions as one electrode of the capacitive element 246, the conductive layer 245 functions as the other electrode of the capacitive element 246, and the insulating layer 243 functions as the dielectric of the capacitive element 246.

[0340] The conductive layer 241 is provided on the insulating layer 261 and embedded in the insulating layer 254. The conductive layer 241 is electrically connected to either the source or drain of the transistor 310 by a plug 266 embedded in the insulating layer 261. The insulating layer 243 is provided covering the conductive layer 241. The conductive layer 245 is provided in the region that overlaps with the conductive layer 241 via the insulating layer 243.

[0341] An insulating layer 255 is provided covering the capacitive element 246, an insulating layer 363 is provided on the insulating layer 255, and light-emitting devices 61R, 61G, and 61B are provided on the insulating layer 363. A protective layer 415 is provided on the light-emitting devices 61R, 61G, and 61B, and a substrate 420 is provided on the upper surface of the protective layer 415 via a resin layer 419.

[0342] The pixel electrodes of the light-emitting device are electrically connected to either the source or drain of the transistor 310 by plugs 256 embedded in insulating layers 255 and 363, a conductive layer 241 embedded in insulating layer 254, and plugs 266 embedded in insulating layer 261.

[0343] Figure 31 shows a modified example of the cross-sectional configuration shown in Figure 30. The main difference between the cross-sectional configuration example of the display device 10 shown in Figure 31 and the cross-sectional configuration example shown in Figure 30 is that transistor 320 is provided instead of transistor 310. Note that explanations of parts that are the same as those in Figure 30 may be omitted.

[0344] Transistor 320 is a transistor in which a metal oxide (also called an oxide semiconductor) is applied to the semiconductor layer where the channel is formed.

[0345] The transistor 320 comprises a semiconductor layer 321, an insulating layer 323, a conductive layer 324, a pair of conductive layers 325, an insulating layer 326, and a conductive layer 327.

[0346] The substrate 331 can be an insulating substrate or a semiconductor substrate.

[0347] An insulating layer 332 is provided on the substrate 331. The insulating layer 332 functions as a barrier layer that prevents impurities such as water or hydrogen from diffusing from the substrate 331 to the transistor 320, and prevents oxygen from detaching from the semiconductor layer 321 to the insulating layer 332. The insulating layer 332 can be made of a film that is less permeable to hydrogen or oxygen than a silicon oxide film, such as an aluminum oxide film, a hafnium oxide film, or a silicon nitride film.

[0348] A conductive layer 327 is provided on an insulating layer 332, and an insulating layer 326 is provided covering the conductive layer 327. The conductive layer 327 functions as the first gate electrode of the transistor 320, and a portion of the insulating layer 326 functions as the first gate insulating layer. It is preferable to use an oxide insulating film, such as a silicon oxide film, for at least the portion of the insulating layer 326 that is in contact with the semiconductor layer 321. It is preferable that the upper surface of the insulating layer 326 is flattened.

[0349] The semiconductor layer 321 is provided on the insulating layer 326. Preferably, the semiconductor layer 321 comprises a metal oxide (also called an oxide semiconductor) film having semiconductor properties. Details of materials suitably used for the semiconductor layer 321 will be described later.

[0350] A pair of conductive layers 325 are provided in contact with the semiconductor layer 321 and function as source and drain electrodes.

[0351] An insulating layer 328 is provided covering the top and side surfaces of a pair of conductive layers 325, as well as the side surfaces of the semiconductor layer 321, and an insulating layer 264 is provided on top of the insulating layer 328. The insulating layer 328 functions as a barrier layer to prevent impurities such as water or hydrogen from diffusing into the semiconductor layer 321 from the insulating layer 264, etc., and to prevent oxygen from detaching from the semiconductor layer 321. The insulating layer 328 can be made of the same insulating film as the insulating layer 332.

[0352] The insulating layer 328 and the insulating layer 264 are provided with openings that reach the semiconductor layer 321. Inside these openings, the insulating layer 323 and the conductive layer 324 are embedded, in contact with the insulating layer 264, the insulating layer 328, the sides of the conductive layer 325, and the upper surface of the semiconductor layer 321. The conductive layer 324 functions as a second gate electrode, and the insulating layer 323 functions as a second gate insulating layer.

[0353] The upper surfaces of the conductive layer 324, the insulating layer 323, and the insulating layer 264 are flattened so that their heights are approximately the same, and the insulating layer 329 and insulating layer 265 are provided covering them.

[0354] Insulating layers 264 and 265 function as interlayer insulating layers. Insulating layer 329 functions as a barrier layer to prevent impurities such as water or hydrogen from diffusing from insulating layer 265 to transistor 320. Insulating layer 329 can be an insulating film similar to that used for insulating layers 328 and 332.

[0355] A plug 274, which is electrically connected to one of the pair of conductive layers 325, is provided so as to be embedded in the insulating layers 265, 329, and 264. Here, it is preferable that the plug 274 comprises a conductive layer 274a that covers the sides of the openings of the insulating layers 265, 329, 264, and 328, and a portion of the upper surface of the conductive layer 325, and a conductive layer 274b that is in contact with the upper surface of the conductive layer 274a. In this case, it is preferable to use a conductive material that does not easily allow hydrogen and oxygen to diffuse as the conductive layer 274a.

[0356] Figure 32 shows an example of a partial cross-sectional configuration of the display device 10 shown in Figure 1B. The display device 10 shown in Figure 32 has a configuration in which a transistor 310A with a channel formed on the substrate 301A of layer 40 and a transistor 310B with a channel formed on the substrate 301A of layer 40 are stacked. The same material as substrate 301 can be used for substrate 301A.

[0357] The display device 10 shown in Figure 32 has a structure in which a layer 60 on which a light-emitting device 61 is provided, a layer 50 on which a substrate 301B, a transistor 310B, and a capacitive element 246 are provided, and a layer 40 on which a substrate 301A and a transistor 310A are provided are bonded together.

[0358] A plug 343 is provided on substrate 301B, which penetrates the substrate 301B. The plug 343 functions as a through-silicon via (TSV). The plug 343 is also electrically connected to a conductive layer 342 provided on the back surface of substrate 301 (the surface opposite to the substrate 420 side). On the other hand, a conductive layer 341 is provided on substrate 301A on an insulating layer 261.

[0359] The conductive layer 341 and the conductive layer 342 are joined together, thereby electrically connecting layer 40 and layer 50.

[0360] It is preferable that conductive layers 341 and 342 use the same conductive material. For example, a metal film containing an element selected from Al, Cr, Cu, Ta, Sn, Zn, Au, Ag, Pt, Ti, Mo, and W, or a metal nitride film (titanium nitride film, molybdenum nitride film, tungsten nitride film) composed of the above elements can be used. In particular, it is preferable to use copper for conductive layers 341 and 342. This allows the application of Cu-Cu (copper-copper) direct bonding technology (a technology that achieves electrical conductivity by connecting Cu (copper) pads to each other). The conductive layer 341 and conductive layer 342 may be bonded via bumps.

[0361] Figure 33 shows a modified example of the cross-sectional configuration shown in Figure 32. The cross-sectional configuration example of the display device 10 shown in Figure 33 has a configuration in which a transistor 310A with a channel formed on a substrate 301A and a transistor 320 containing a metal oxide on the semiconductor layer in which the channel is formed are stacked. Note that explanations of parts similar to those in Figures 30 to 32 may be omitted.

[0362] The layer 50 shown in Figure 33 has the same configuration as the layer 50 shown in Figure 31, but without the substrate 331. In the layer 40 shown in Figure 33, an insulating layer 261 is provided covering the transistor 310A, and a conductive layer 251 is provided on the insulating layer 261. An insulating layer 262 is provided covering the conductive layer 251, and a conductive layer 252 is provided on the insulating layer 262. The conductive layers 251 and 252 each function as wiring. An insulating layer 263 and an insulating layer 332 are provided covering the conductive layer 252, and a transistor 320 is provided on the insulating layer 332. An insulating layer 265 is provided covering the transistor 320, and a capacitive element 246 is provided on the insulating layer 265. The capacitive element 246 and the transistor 320 are electrically connected by a plug 274. Layer 50 is provided on top of the insulating layer 263 of layer 40.

[0363] Transistor 320 can be used as a transistor constituting the pixel circuit 51. Transistor 310 can also be used as a transistor constituting the pixel circuit 51 or as a transistor constituting a peripheral drive circuit. Furthermore, transistors 310 and 320 can be used as transistors constituting functional circuits such as arithmetic circuits or memory circuits.

[0364] This configuration allows for the formation of peripheral drive circuits and other components directly beneath the layer 60 containing the light-emitting device 61, in addition to the pixel circuit 51. Therefore, it becomes possible to miniaturize the display device compared to the case where the drive circuits are located around the display area.

[0365] Note that Figures 30 to 33 omit dummy transistors and dummy layers. In a top view, it is preferable that the proportion of the total area of ​​layers provided on the same surface be within the range described above. By increasing the proportion of the total area of ​​layers provided on the same surface, the generation of foreign matter caused by the resist mask can be suppressed during the manufacturing process, and the manufacturing yield can be increased.

[0366] The configuration shown in this embodiment can be used in appropriate combination with the configurations shown in other embodiments and examples.

[0367] (Embodiment 3) This embodiment describes a transistor that can be used in a semiconductor device according to one aspect of the present invention.

[0368] <Example of transistor configuration> Figures 34A, 34B, and 34C are a top view and a cross-sectional view of a transistor 500 that can be used in a semiconductor device according to one aspect of the present invention. The transistor 500 can be applied to a semiconductor device according to one aspect of the present invention.

[0369] Figure 34A is a top view of transistor 500. Figures 34B and 34C are cross-sectional views of transistor 500. Here, Figure 34B is a cross-sectional view of the area indicated by the dashed line A1-A2 in Figure 34A, and is also a cross-sectional view of transistor 500 in the channel length direction. Similarly, Figure 34C is a cross-sectional view of the area indicated by the dashed line A3-A4 in Figure 34A, and is also a cross-sectional view of transistor 500 in the channel width direction. Note that in the top view of Figure 34A, some elements have been omitted for clarity.

[0370] As shown in Figure 34, the transistor 500 includes a metal oxide 531a disposed on a substrate (not shown), a metal oxide 531b disposed on the metal oxide 531a, conductors 542a and 542b disposed on the metal oxide 531b at a distance from each other, an insulator 580 disposed on the conductors 542a and 542b with an opening formed between the conductors 542a and 542b, a conductor 560 disposed in the opening, an insulator 550 disposed between the metal oxide 531b, conductor 542a, conductor 542b, insulator 580, and conductor 560, and a metal oxide 531c disposed between the metal oxide 531b, conductor 542a, conductor 542b, insulator 580, and insulator 550. Here, as shown in Figures 34B and 34C, it is preferable that the upper surface of the conductor 560 substantially coincides with the upper surfaces of the insulator 550, insulator 554, metal oxide 531c, and insulator 580. In the following, metal oxide 531a, metal oxide 531b, and metal oxide 531c may be collectively referred to as metal oxide 531. Also, conductors 542a and conductor 542b may be collectively referred to as conductor 542.

[0371] In the transistor 500 shown in Figure 34, the sides of the conductors 542a and 542b facing the conductor 560 have a generally vertical shape. However, the transistor 500 shown in Figure 34 is not limited to this, and the angle between the side and bottom surfaces of the conductors 542a and 542b may be 10° to 80°, preferably 30° to 60°. Furthermore, the opposing sides of the conductors 542a and 542b may have multiple surfaces.

[0372] As shown in Figure 34, it is preferable that an insulator 554 is placed between the insulator 524, metal oxide 531a, metal oxide 531b, conductor 542a, conductor 542b, and metal oxide 531c and the insulator 580. Here, it is preferable that the insulator 554 is in contact with the side surface of the metal oxide 531c, the top and side surfaces of the conductor 542a, the top and side surfaces of the conductor 542b, the side surfaces of the metal oxide 531a and metal oxide 531b, and the top surface of the insulator 524, as shown in Figures 34B and 34C.

[0373] In the transistor 500, a configuration is shown in which three layers of metal oxide 531a, metal oxide 531b, and metal oxide 531c are stacked in the channel formation region and its vicinity, but the present invention is not limited thereto. For example, a two-layer structure of metal oxide 531b and metal oxide 531c, or a stacked structure of four or more layers, may be provided. Also, in the transistor 500, the conductor 560 is shown as a two-layer stacked structure, but the present invention is not limited thereto. For example, the conductor 560 may be a single-layer structure or a stacked structure of three or more layers. Furthermore, each of the metal oxide 531a, metal oxide 531b, and metal oxide 531c may have a stacked structure of two or more layers.

[0374] For example, if the metal oxide 531c 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 531b and the second metal oxide has the same composition as metal oxide 531a.

[0375] Here, the conductor 560 functions as the gate electrode of the transistor, and the conductors 542a and 542b function as the source electrode or drain electrode, respectively. As described above, the conductor 560 is formed to be embedded in the opening of the insulator 580 and in the region sandwiched between the conductors 542a and 542b. Here, the arrangement of the conductors 560, 542a, and 542b is selected in a self-aligned manner with respect to the opening of the insulator 580. In other words, in the transistor 500, the gate electrode can be positioned in a self-aligned manner between the source electrode and the drain electrode. Therefore, since the conductor 560 can be formed without providing a positional margin, the area of ​​the transistor 500 can be reduced. This makes it possible to make the display device high-resolution. Also, the bezel of the display device can be narrowed.

[0376] As shown in Figure 34, it is preferable that the conductor 560 has a conductor 560a provided inside the insulator 550 and a conductor 560b provided so as to be embedded inside the conductor 560a.

[0377] The transistor 500 preferably includes an insulator 514 disposed on a substrate (not shown), an insulator 516 disposed on top of the insulator 514, a conductor 505 disposed so as to be embedded in the insulator 516, an insulator 522 disposed on top of the insulator 516 and the conductor 505, and an insulator 524 disposed on top of the insulator 522. It is preferable that a metal oxide 531a is disposed on top of the insulator 524.

[0378] It is preferable that an insulator 574 and an insulator 581, which function as interlayer films, are placed on top of the transistor 500. Here, it is preferable that the insulator 574 is placed in contact with the upper surfaces of the conductor 560, insulator 550, insulator 554, metal oxide 531c, and insulator 580.

[0379] It is preferable that insulators 522, 554, and 574 have a function to suppress the diffusion of hydrogen (for example, at least one such as a hydrogen atom or a hydrogen molecule). For example, it is preferable that insulators 522, 554, and 574 have lower hydrogen permeability than insulators 524, 550, and 580. It is also preferable that insulators 522 and 554 have a function to suppress the diffusion of oxygen (for example, at least one such as an oxygen atom or an oxygen molecule). For example, it is preferable that insulators 522 and 554 have lower oxygen permeability than insulators 524, 550, and 580.

[0380] Here, insulator 524, metal oxide 531, and insulator 550 are separated from insulators 580 and 581 by insulators 554 and 574. Therefore, it is possible to suppress the mixing of impurities such as hydrogen and excess oxygen contained in insulators 580 and 581 into insulators 524, metal oxide 531a, metal oxide 531b, and insulator 550.

[0381] It is preferable that a conductor 545 (conductor 545a and conductor 545b) is provided that is electrically connected to the transistor 500 and functions as a plug. In addition, an insulator 541 (insulator 541a and insulator 541b) is provided in contact with the side surface of the conductor 545 that functions as a plug. That is, the insulator 541 is provided in contact with the inner wall of the opening of the insulator 554, insulator 580, insulator 574, and insulator 581. Alternatively, a first conductor of the conductor 545 may be provided in contact with the side surface of the insulator 541, and a second conductor of the conductor 545 may be provided further inside. Here, the height of the upper surface of the conductor 545 and the height of the upper surface of the insulator 581 can be made to be approximately the same. Although the transistor 500 shows a configuration in which the first conductor and the second conductor of the conductor 545 are stacked, the present invention is not limited to this. For example, the conductor 545 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.

[0382] In transistor 500, 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 531 (metal oxide 531a, metal oxide 531b, and metal oxide 531c) 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 metal oxide 531.

[0383] 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 and Sn or both.

[0384] As shown in Figure 34B, the thickness of the metal oxide 531b in the region that does not overlap with the conductor 542 may be thinner than the thickness of the metal oxide 531b in the region that overlaps with the conductor 542. This is formed by removing a portion of the upper surface of the metal oxide 531b when forming the conductors 542a and 542b. When a conductive film that will become the conductor 542 is deposited on the upper surface of the metal oxide 531b, a region with low resistance may be formed near the interface with the conductive film. Thus, by removing the region with low resistance located between the conductors 542a and 542b on the upper surface of the metal oxide 531b, it is possible to prevent the formation of a channel in that region.

[0385] 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 can be provided. Alternatively, a display device with a stable electrical characteristic transistor can be provided and highly reliable can be provided. Alternatively, a display device with a small off-current transistor can be provided and low power consumption can be provided.

[0386] A detailed configuration of the transistor 500, which can be used in a display device according to one aspect of the present invention, will be described.

[0387] The conductor 505 is arranged to have an overlapping region with the metal oxide 531 and the conductor 560. Furthermore, it is preferable that the conductor 505 is embedded in the insulator 516.

[0388] The conductor 505 comprises conductor 505a, conductor 505b, and conductor 505c. Conductor 505a is provided in contact with the bottom surface and side wall of an opening provided in the insulator 516. Conductor 505b is provided so as to be embedded in a recess formed in conductor 505a. Here, the upper surface of conductor 505b is lower than the upper surface of conductor 505a and the upper surface of the insulator 516. Conductor 505c is provided in contact with the upper surface of conductor 505b and the side surface of conductor 505a. Here, the height of the upper surface of conductor 505c is approximately equal to the height of the upper surface of conductor 505a and the upper surface of the insulator 516. In other words, conductor 505b is enclosed by conductors 505a and conductor 505c.

[0389] It is preferable to use conductive materials for conductors 505a and 505c 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).

[0390] By using conductive materials that have the function of reducing hydrogen diffusion for conductors 505a and 505c, it is possible to suppress the diffusion of impurities such as hydrogen contained in conductor 505b into the metal oxide 531 via the insulator 524, etc. Furthermore, by using conductive materials that have the function of suppressing oxygen diffusion for conductors 505a and 505c, it is possible to suppress the oxidation of conductor 505b and the resulting decrease in conductivity. It is preferable to use conductive materials that have the function of suppressing oxygen diffusion, such as titanium, titanium nitride, tantalum, tantalum nitride, ruthenium, ruthenium oxide, etc. Therefore, conductor 505a may be made of the above conductive material in a single layer or a laminate. For example, titanium nitride may be used for conductor 505a.

[0391] The conductor 505b is preferably a conductive material mainly composed of tungsten, copper, or aluminum. For example, tungsten may be used for the conductor 505b.

[0392] Here, conductor 560 may function as the first gate (also called the top gate) electrode. Also, conductor 505 may function as the second gate (also called the bottom gate) electrode. In that case, by changing the potential applied to conductor 505 independently of the potential applied to conductor 560, the V of transistor 500 can be controlled. th This can be controlled. In particular, by applying a negative potential to the conductor 505, the V of transistor 500 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 505 reduces the drain current when the potential applied to the conductor 560 is 0V compared to not applying a potential.

[0393] The conductor 505 should be larger than the channel-forming region in the metal oxide 531. In particular, as shown in Figure 34C, it is preferable that the conductor 505 extends to the region outside the end that intersects with the channel width direction of the metal oxide 531. That is, it is preferable that the conductor 505 and the conductor 560 are superimposed on the outside of the side surface in the channel width direction of the metal oxide 531, with an insulator in between.

[0394] With the above configuration, the channel-forming region of the metal oxide 531 can be electrically surrounded by the electric field of the conductor 560, which functions as the first gate electrode, and the electric field of the conductor 505, which functions as the second gate electrode.

[0395] As shown in Figure 34C, the conductor 505 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 505.

[0396] The insulator 514 preferably functions as a barrier insulating film that suppresses the ingress of impurities such as water or hydrogen into the transistor 500 from the substrate side. Therefore, it is preferable to use an insulating material for the insulator 514 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 (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) (the above oxygen is less permeable).

[0397] For example, it is preferable to use aluminum oxide or silicon nitride as the insulator 514. This suppresses the diffusion of impurities such as water or hydrogen from the substrate side to the transistor 500 side beyond the insulator 514. Alternatively, it suppresses the diffusion of oxygen contained in the insulator 524, etc., to the substrate side beyond the insulator 514.

[0398] The insulators 516, 580, and 581 that function as interlayer films preferably have a lower dielectric constant than the insulator 514. By using a material with a low dielectric constant as the interlayer film, the parasitic capacitance generated between wirings can be reduced. For example, as the insulators 516, 580, and 581, silicon oxide, silicon oxynitride, silicon nitride oxynitride, silicon nitride, silicon oxide with fluorine added, silicon oxide with carbon added, silicon oxide with carbon and nitrogen added, or silicon oxide having pores may be appropriately used.

[0399] The insulators 522 and 524 have a function as a gate insulator.

[0400] Here, the insulator 524 in contact with the metal oxide 531 preferably desorbs oxygen by heating. In this specification, oxygen desorbed by heating may be referred to as excess oxygen. For example, the insulator 524 may be appropriately silicon oxide or silicon oxynitride. By providing an oxygen-containing insulator in contact with the metal oxide 531, oxygen vacancies in the metal oxide 531 can be reduced, and the reliability of the transistor 500 can be improved.

[0401] Specifically, as the insulator 524, it is preferable to use an oxide material in which some oxygen desorbs by heating. An oxide that desorbs oxygen by heating is an oxide film in which the desorption amount of oxygen converted to oxygen atoms is 1.0×10 18 atoms / cm 3 or more, preferably 1.0×10 19 atoms / cm 3 or more, more preferably 2.0×10 19 atoms / cm 3 or more, or 3.0×10 20 atoms / cm 3 or more. The surface temperature of the film during the above TDS analysis is preferably in the range of 100°C or higher and 700°C or lower, or 100°C or higher and 400°C or lower.

[0402] As shown in Figure 34C, the thickness of the insulator 524 in the region that does not overlap with the insulator 554 and does not overlap with the metal oxide 531b may be thinner than the thickness of the other regions. In the insulator 524, it is preferable that the thickness of the region that does not overlap with the insulator 554 and does not overlap with the metal oxide 531b is such that the above-mentioned oxygen can diffuse sufficiently.

[0403] It is preferable that the insulator 522 functions as a barrier insulating film that suppresses the ingress of impurities such as water or hydrogen into the transistor 500 from the substrate side, similar to the insulator 514, etc. For example, it is preferable that the insulator 522 has lower hydrogen permeability than the insulator 524. By surrounding the insulator 524, metal oxide 531, and insulator 550, etc., with the insulators 522, 554, and 574, it is possible to suppress the ingress of impurities such as water or hydrogen into the transistor 500 from the outside.

[0404] Furthermore, it is preferable that the insulator 522 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 522 has lower oxygen permeability than the insulator 524. It is preferable that the insulator 522 has a function to suppress the diffusion of oxygen and impurities, thereby reducing the diffusion of oxygen contained in the metal oxide 531 to the substrate side. In addition, it is possible to suppress the reaction of the conductor 505 with the oxygen contained in the insulator 524 and the metal oxide 531.

[0405] The insulator 522 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 522 is formed using such a material, the insulator 522 functions as a layer that suppresses the release of oxygen from the metal oxide 531 and the incorporation of impurities such as hydrogen from the periphery of the transistor 500 into the metal oxide 531.

[0406] 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 oxynitride, or silicon nitride may be laminated onto the above insulators.

[0407] The insulator 522 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 is possible to reduce the gate potential during transistor operation while maintaining the physical film thickness.

[0408] Furthermore, the insulators 522 and 524 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 524 may be provided below the insulator 522.

[0409] The metal oxide 531 comprises a metal oxide 531a, a metal oxide 531b on the metal oxide 531a, and a metal oxide 531c on the metal oxide 531b. By having the metal oxide 531a below the metal oxide 531b, the diffusion of impurities from structures formed below the metal oxide 531a to the metal oxide 531b can be suppressed. Furthermore, by having the metal oxide 531c on the metal oxide 531b, the diffusion of impurities from structures formed above the metal oxide 531c to the metal oxide 531b can be suppressed.

[0410] Furthermore, it is preferable that the metal oxide 531 has a layered structure of multiple oxide layers with different atomic ratios of each metal atom. For example, if the metal oxide 531 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 531a to the total number of atoms of all elements constituting metal oxide 531a is higher than the ratio of the number of atoms of element M contained in metal oxide 531b to the total number of atoms of all elements constituting metal oxide 531b. It is also preferable that the atomic ratio of element M contained in metal oxide 531a to In is higher than the atomic ratio of element M contained in metal oxide 531b to In. Here, metal oxide 531c can be any metal oxide that can be used for metal oxide 531a or metal oxide 531b.

[0411] It is preferable that the energy at the lower end of the conduction band of metal oxide 531a and metal oxide 531c is higher than the energy at the lower end of the conduction band of metal oxide 531b. In other words, it is preferable that the electron affinity of metal oxide 531a and metal oxide 531c is smaller than the electron affinity of metal oxide 531b. In this case, it is preferable that metal oxide 531c is a metal oxide that can be used for metal oxide 531a. Specifically, it is preferable that the ratio of the number of atoms of element M contained in metal oxide 531c to the total number of atoms of all elements constituting metal oxide 531c is higher than the ratio of the number of atoms of element M contained in metal oxide 531b to the total number of atoms of all elements constituting metal oxide 531b. It is also preferable that the atomic ratio of element M contained in metal oxide 531c to In is higher than the atomic ratio of element M contained in metal oxide 531b to In.

[0412] Here, at the junctions of metal oxide 531a, metal oxide 531b, and metal oxide 531c, the energy levels at the lower end of the conduction band change smoothly. In other words, the energy levels at the lower end of the conduction band at the junctions of metal oxide 531a, metal oxide 531b, and metal oxide 531c 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 531a and metal oxide 531b, and at the interface between metal oxide 531b and metal oxide 531c.

[0413] Specifically, by having metal oxide 531a and metal oxide 531b, and metal oxide 531b and metal oxide 531c, share a common element other than oxygen (which serves as the main component), a mixed layer with a low defect level density can be formed. For example, if metal oxide 531b is In-Ga-Zn oxide, then In-Ga-Zn oxide, Ga-Zn oxide, gallium oxide, etc., may be used as metal oxide 531a and metal oxide 531c. Furthermore, metal oxide 531c 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 531c.

[0414] Specifically, for metal oxide 531a, 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 531b, a metal oxide with an atomic ratio of In:Ga:Zn = 4:2:3 or 3:1:2 may be used. For metal oxide 531c, 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 531c 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.

[0415] In this case, the main carrier pathway is through metal oxide 531b. By configuring metal oxide 531a and metal oxide 531c as described above, the defect level density at the interface between metal oxide 531a and metal oxide 531b, and at the interface between metal oxide 531b and metal oxide 531c, can be reduced. As a result, the influence of interface scattering on carrier conduction is reduced, and transistor 500 can obtain high on-current and high frequency characteristics. Furthermore, if metal oxide 531c is in a multilayer structure, in addition to the effect of reducing the defect level density at the interface between metal oxide 531b and metal oxide 531c as described above, it is expected that the diffusion of constituent elements of metal oxide 531c towards the insulator 550 will be suppressed. More specifically, by making metal oxide 531c 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 550. Since the insulator 550 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 531c, it becomes possible to provide a highly reliable display device.

[0416] A conductor 542 (conductor 542a and conductor 542b) that functions as a source electrode and a drain electrode is provided on the metal oxide 531b. 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 542, 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.

[0417] By providing the conductor 542 in contact with the metal oxide 531, the oxygen concentration in the vicinity of the conductor 542 on the metal oxide 531 may be reduced. Furthermore, a metal compound layer containing the metal in the conductor 542 and components of the metal oxide 531 may be formed in the vicinity of the conductor 542 on the metal oxide 531. In such cases, the carrier density increases in the region of the metal oxide 531 near the conductor 542, resulting in a low-resistance region.

[0418] Here, the region between the conductor 542a and the conductor 542b is formed superimposed on the opening of the insulator 580. This allows the conductor 560 to be positioned self-aligned between the conductor 542a and the conductor 542b.

[0419] The insulator 550 functions as a gate insulator. It is preferable that the insulator 550 be placed in contact with the upper surface of the metal oxide 531c. The insulator 550 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.

[0420] Similar to the insulator 524, it is preferable that the concentration of impurities such as water or hydrogen in the insulator 550 is reduced. The film thickness of the insulator 550 is preferably 1 nm or more and 20 nm or less.

[0421] A metal oxide may be provided between the insulator 550 and the conductor 560. It is preferable that the metal oxide suppresses oxygen diffusion from the insulator 550 to the conductor 560. This suppresses the oxidation of the conductor 560 by oxygen in the insulator 550.

[0422] The metal oxide may function as part of the gate insulator. Therefore, when silicon oxide or silicon oxynitride is used for the insulator 550, 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 550 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.

[0423] 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 oxides containing aluminum and hafnium (hafnium aluminate).

[0424] Although the conductor 560 is shown as a two-layer structure in Figure 34, it may also be a single-layer structure or a laminated structure of three or more layers.

[0425] It is preferable to use a conductor 560a 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).

[0426] The conductor 560a has the function of suppressing oxygen diffusion, thereby preventing the conductor 560b from oxidizing due to oxygen contained in the insulator 550 and reducing its conductivity. It is preferable to use, for example, tantalum, tantalum nitride, ruthenium, or ruthenium oxide as a conductive material that has the function of suppressing oxygen diffusion.

[0427] The conductor 560b is preferably made of a conductive material mainly composed of tungsten, copper, or aluminum. Furthermore, since the conductor 560 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 560b may also be in a laminated structure; for example, it may be a laminated structure of titanium or titanium nitride and the above-mentioned conductive material.

[0428] As shown in Figures 34A and 34C, in the region of the metal oxide 531b that does not overlap with the conductor 542, in other words, in the channel-forming region of the metal oxide 531, the side surface of the metal oxide 531 is covered by the conductor 560. This makes it easier to apply the electric field of the conductor 560, which functions as the first gate electrode, to the side surface of the metal oxide 531. Therefore, the on-current of the transistor 500 can be increased and the frequency characteristics can be improved.

[0429] The insulator 554, like the insulator 514, preferably functions as a barrier insulating film that suppresses the ingress of impurities such as water or hydrogen into the transistor 500 from the insulator 580 side. For example, it is preferable that the insulator 554 has lower hydrogen permeability than the insulator 524. Furthermore, as shown in Figures 34B and 34C, it is preferable that the insulator 554 is in contact with the side surface of the metal oxide 531c, the top and side surfaces of the conductor 542a, the top and side surfaces of the conductor 542b, the side surfaces of the metal oxide 531a and metal oxide 531b, and the top surface of the insulator 524. With this configuration, it is possible to suppress the ingress of hydrogen contained in the insulator 580 into the metal oxide 531 from the top or side surfaces of the conductor 542a, conductor 542b, metal oxide 531a, metal oxide 531b, and the insulator 524.

[0430] Furthermore, it is preferable that the insulator 554 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 554 has lower oxygen permeability than the insulator 580 or the insulator 524.

[0431] The insulator 554 is preferably deposited using a sputtering method. By depositing the insulator 554 using a sputtering method in an oxygen-containing atmosphere, oxygen can be added to the vicinity of the region of the insulator 524 that is in contact with the insulator 554. This allows oxygen to be supplied from this region to the metal oxide 531 via the insulator 524. Here, the insulator 554 has a function to suppress upward diffusion of oxygen, thereby preventing oxygen from diffusing from the metal oxide 531 to the insulator 580. In addition, the insulator 522 has a function to suppress downward diffusion of oxygen, thereby preventing oxygen from diffusing from the metal oxide 531 to the substrate side. In this way, oxygen is supplied to the channel formation region of the metal oxide 531. This reduces oxygen deficiency in the metal oxide 531 and suppresses normally-on formation of the transistor.

[0432] As the insulator 554, 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.

[0433] The insulator 524, insulator 550, and metal oxide 531 are covered by the hydrogen barrier insulator 554, so the insulator 580 is separated from the insulator 524, metal oxide 531, and insulator 550 by the insulator 554. This prevents impurities such as hydrogen from entering the transistor 500 from the outside, thus providing the transistor 500 with good electrical characteristics and reliability.

[0434] The insulator 580 is provided on the insulator 524, the metal oxide 531, and the conductor 542 via the insulator 554. For example, the insulator 580 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.

[0435] It is preferable that the concentration of impurities such as water or hydrogen in the insulator 580 is reduced. Furthermore, the upper surface of the insulator 580 may be flattened.

[0436] The insulator 574 preferably functions as a barrier insulating film that suppresses the incorporation of impurities such as water or hydrogen into the insulator 580 from above, similar to the insulator 514. For example, the insulator 574 can be an insulator that can be used for the insulator 514, insulator 554, etc.

[0437] It is preferable to provide an insulator 581, which functions as an interlayer film, on top of the insulator 574. It is preferable that the insulator 581, like the insulator 524, has a reduced concentration of impurities such as water or hydrogen in the film.

[0438] Conductors 545a and 545b are placed in the openings formed in insulators 581, 574, 580, and 554. Conductors 545a and 545b are provided facing each other with conductor 560 in between. The height of the upper surfaces of conductors 545a and 545b may be on the same plane as the upper surface of insulator 581.

[0439] Furthermore, an insulator 541a is provided in contact with the inner wall of the opening of insulators 581, 574, 580, and 554, and a first conductive portion of conductor 545a is formed in contact with its side surface. Conductor 542a is located in at least a portion of the bottom of the opening, and conductor 545a is in contact with conductor 542a. Similarly, an insulator 541b is provided in contact with the inner wall of the opening of insulators 581, 574, 580, and 554, and a first conductive portion of conductor 545b is formed in contact with its side surface. Conductor 542b is located in at least a portion of the bottom of the opening, and conductor 545b is in contact with conductor 542b.

[0440] It is preferable that the conductors 545a and 545b are made of conductive materials mainly composed of tungsten, copper, or aluminum. Furthermore, the conductors 545a and 545b may be arranged in a laminated structure.

[0441] When the conductor 545 is in 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 531a, metal oxide 531b, conductor 542, insulator 554, insulator 580, insulator 574, and insulator 581. 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 in a laminate. By using such a conductive material, it is possible to suppress the absorption of oxygen added to the insulator 580 by the conductors 545a and 545b. In addition, it is possible to suppress the mixing of impurities such as water or hydrogen from the layer above the insulator 581 into the metal oxide 531 through the conductors 545a and 545b.

[0442] For insulators 541a and 541b, for example, insulators that can be used for insulator 554 may be used. Since insulators 541a and 541b are provided in contact with insulator 554, it is possible to suppress the mixing of impurities such as water or hydrogen from insulator 580, etc., into the metal oxide 531 through conductors 545a and 545b. Furthermore, it is possible to suppress the absorption of oxygen contained in insulator 580 into conductors 545a and 545b.

[0443] Although not shown in the figures, conductors that function as wiring may be placed in contact with the upper surfaces of conductor 545a and conductor 545b. The conductors that function as wiring are preferably made of a conductive material mainly composed of tungsten, copper, or aluminum. The conductors may also be in a laminated structure, for example, a laminate of titanium or titanium nitride and the conductive material. The conductors may be formed to be embedded in an opening provided in the insulator.

[0444] <Materials that make up a transistor> This section describes the constituent materials that can be used in transistors.

[0445] [substrate] As a substrate for forming the transistor 500, for example, an insulating substrate, a semiconductor substrate, or a conductive substrate may be used. Examples of insulating substrates include glass substrates, quartz substrates, sapphire substrates, stabilized zirconia substrates (such as yttria-stabilized zirconia substrates), and resin substrates. Examples of semiconductor substrates include silicon, germanium, and other semiconductor substrates, or compound semiconductor substrates made of silicon carbide, silicon germanium, gallium arsenide, indium phosphide, zinc oxide, and gallium oxide. Furthermore, there are semiconductor substrates having insulating regions within the aforementioned semiconductor substrates, such as SOI (Silicon On Insulator) substrates. Examples of conductive substrates include graphite substrates, metal substrates, alloy substrates, and conductive resin substrates. Alternatively, there are substrates having metal nitrides, substrates having metal oxides, etc. Furthermore, there are substrates on which a conductor or semiconductor is provided on an insulating substrate, substrates on which a conductor or insulator is provided on a semiconductor substrate, and substrates on which a semiconductor or insulator is provided on a conductive substrate. Alternatively, substrates on which elements are provided may be used. Elements provided on a substrate include capacitive elements, resistive elements, switch elements, light-emitting devices, and memory elements.

[0446] [Insulator] Insulators include insulating oxides, nitrides, oxidized nitrides, nitride oxides, metal oxides, metal oxidized nitrides, and metal nitride oxides.

[0447] For example, 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 for the insulator that functions as the gate insulator, it is possible to lower the voltage during transistor operation while maintaining the physical film thickness. On the other hand, by using a material with a low dielectric constant for the insulator that functions as the interlayer film, parasitic capacitance between wiring can be reduced. Therefore, it is best to select the material according to the function of the insulator.

[0448] Examples of insulators with high dielectric constants include gallium oxide, hafnium oxide, zirconium oxide, oxides containing aluminum and hafnium, oxiditrides containing aluminum and hafnium, oxides containing silicon and hafnium, oxiditrides containing silicon and hafnium, or nitrides containing silicon and hafnium.

[0449] Examples of insulators with low dielectric constant include silicon oxide, silicon oxide nitride, silicon oxide nitride, silicon nitride, silicon oxide with added fluorine, silicon oxide with added carbon, silicon oxide with added carbon and nitrogen, silicon oxide with voids, or resins.

[0450] Transistors using oxide semiconductors can have their electrical characteristics stabilized by surrounding them with an insulator (insulator 514, insulator 522, insulator 554, and insulator 574, etc.) that has the function of suppressing the permeation of impurities such as hydrogen and oxygen. As an insulator that has the function of suppressing the permeation of impurities such as hydrogen and oxygen, for example, an insulator 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 multilayer structure. Specifically, as an insulator that has the function of suppressing the permeation of impurities such as hydrogen and oxygen, metal oxides such as aluminum oxide, magnesium oxide, gallium oxide, germanium oxide, yttrium oxide, zirconium oxide, lanthanum oxide, neodymium oxide, hafnium oxide, or tantalum oxide, metal nitrides such as aluminum nitride, titanium aluminum nitride, titanium nitride, silicon oxide, or silicon nitride can be used.

[0451] The insulator that functions as a gate insulator is preferably an insulator that has a region containing oxygen that is desorbed by heating. For example, by having a structure in which silicon oxide or silicon oxynitride having a region containing oxygen that is desorbed by heating is in contact with the metal oxide 531, the oxygen deficiency of the metal oxide 531 can be compensated for.

[0452] [conductor] It is preferable to use a metallic 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, lanthanum, etc., as a conductor, or an alloy containing the above metallic elements, or an alloy combining the above metallic 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. Alternatively, semiconductors with high electrical conductivity, such as polycrystalline silicon containing impurity elements like phosphorus, or silicides such as nickel silicide may be used.

[0453] Multiple conductors formed from the above materials may be used in a laminated structure. For example, a laminated structure may be formed by combining a material containing the aforementioned metal element with a conductive material containing oxygen. Alternatively, a laminated structure may be formed by combining a material containing the aforementioned metal element with a conductive material containing nitrogen. Furthermore, a laminated structure may be formed by combining a material containing the aforementioned metal element with a conductive material containing oxygen and a conductive material containing nitrogen.

[0454] Furthermore, when using a metal oxide for the channel formation region of a transistor, it is preferable to use a laminated structure for the conductor functioning as the gate electrode, which combines a material containing the aforementioned metal element with a conductive material containing oxygen. In this case, it is preferable to place the conductive material containing oxygen on the channel formation region side. By placing the conductive material containing oxygen on the channel formation region side, oxygen released from the conductive material is more easily supplied to the channel formation region.

[0455] In particular, it is preferable to use a conductive material containing metal elements and oxygen contained in the metal oxide in which the channel is formed as the conductor that functions as the gate electrode. Alternatively, conductive materials containing the aforementioned metal elements and nitrogen may be used. For example, conductive materials containing nitrogen such as titanium nitride and tantalum nitride may be used. In addition, 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 silicon-doped indium tin oxide may be used. In addition, indium gallium zinc oxide containing nitrogen may be used. By using such materials, it may be possible to capture hydrogen contained in the metal oxide in which the channel is formed. Alternatively, it may be possible to capture hydrogen that is mixed in from an external insulator or the like.

[0456] This embodiment can be implemented in appropriate combination with other embodiments described herein, at least in part.

[0457] The configuration shown in this embodiment can be used in appropriate combination with the configurations shown in other embodiments and examples.

[0458] (Embodiment 4) This embodiment describes metal oxides (hereinafter also referred to as oxide semiconductors) that can be used in the OS transistor described in the above embodiment.

[0459] <Classification of crystal structures> First, we will explain the classification of crystal structures in oxide semiconductors using Figure 35A. Figure 35A is a diagram illustrating the classification of crystal structures in oxide semiconductors, specifically IGZO (a metal oxide containing In, Ga, and Zn).

[0460] As shown in Figure 35A, 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.

[0461] The structure within the thick frame shown in Figure 35A 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 "Crystal" or the energetically unstable "Amorphous."

[0462] The crystal structure of a film or substrate can be evaluated using X-ray diffraction (XRD) spectroscopy. Figure 35B shows the XRD spectrum obtained by GIXD (Grazing-Incidence XRD) measurement of a CAAC-IGZO film classified as "Crystalline" (the horizontal axis is 2θ [deg.], and the vertical axis represents intensity in arbitrary units (au)). The GIXD method is also known as the thin-film method or the Seemann-Bohlin method. Hereafter, the XRD spectrum obtained by the GIXD measurement shown in Figure 35B will simply be referred to as the XRD spectrum. The composition of the CAAC-IGZO film shown in Figure 35B is approximately In:Ga:Zn = 4:2:3 [atomic ratio]. The thickness of the CAAC-IGZO film shown in Figure 35B is 500 nm.

[0463] As shown in Figure 35B, 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 35B, the peak near 2θ=31° is asymmetrical with respect to the angle at which the peak intensity was detected.

[0464] The crystal structure of a film or substrate can be evaluated by the diffraction pattern (also called the nano-beam electron diffraction pattern) observed using nano-beam electron diffraction (NBED). The diffraction pattern of a CAAC-IGZO film is shown in Figure 35C. Figure 35C 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 35C is approximately In:Ga:Zn = 4:2:3 [atomic ratio]. Furthermore, in nano-beam electron diffraction, electron diffraction is performed with a probe diameter of 1 nm.

[0465] As shown in Figure 35C, the diffraction pattern of the CAAC-IGZO film shows multiple spots indicating c-axis orientation.

[0466] [Structure of oxide semiconductors] Note that when focusing on the crystal structure, oxide semiconductors may be classified differently from those shown in Figure 35A. 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), amorphous oxide semiconductors, etc.

[0467] Here, we will explain the details of the CAAC-OS, nc-OS, and a-like OS mentioned above.

[0468] [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.

[0469] 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.

[0470] In In-M-Zn oxide (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). Indium and element M are mutually substitutable. Therefore, the (M,Zn) layer may contain indium. The In layer may also contain element M. The In layer may also contain Zn. This layered structure can be observed, for example, as a lattice image in high-resolution TEM images.

[0471] 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 peak indicating c-axis orientation (value of 2θ) may vary depending on the type and composition of the metal elements constituting the CAAC-OS.

[0472] 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.

[0473] 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 factors such as the non-dense arrangement of oxygen atoms in the ab-plane direction and the change in interatomic bond distances due to the substitution of metal atoms.

[0474] 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, which does not exhibit clear grain boundaries, 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 effectively than In oxide.

[0475] 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 / or 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.

[0476] [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 and 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.

[0477] [a-like OS] a-like OS is an oxide semiconductor having a structure between nc-OS and amorphous oxide semiconductors. a-like OS has porous or low-density regions. In other words, a-like OS has lower crystallinity compared to nc-OS and CAAC-OS. Also, a-like OS has a higher hydrogen concentration in the film compared to nc-OS and CAAC-OS.

[0478] [Oxide semiconductor configuration] Next, we will explain the details of CAC-OS mentioned above. Note that CAC-OS refers to the material composition.

[0479] [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.

[0480] 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.

[0481] 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.

[0482] 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.

[0483] Furthermore, a clear boundary may not be observed between the first region and the second region described above.

[0484] 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.

[0485] When CAC-OS is used in a transistor, the conductivity due to the first region and the insulation due to the second region work complementaryly to give CAC-OS a switching function (on / off function). In other words, CAC-OS has conductive function in part of the material, insulating function in part of the material, and semiconductor function as a whole. By separating the conductive function and the insulating function, both functions can be maximized. Therefore, by using CAC-OS in a transistor, a high on-current (I) can be achieved. on This enables high field-effect mobility (μ) and good switching operation.

[0486] Oxide semiconductors can take on diverse structures, each possessing different properties. One embodiment of the present invention may include two or more of the following: amorphous oxide semiconductors, polycrystalline oxide semiconductors, a-like OS, CAC-OS, nc-OS, and CAAC-OS.

[0487] <Transistors containing oxide semiconductors> Next, we will explain the case where the above oxide semiconductor is used in a transistor.

[0488] By using the above-mentioned oxide semiconductor in transistors, it is possible to realize transistors with high field-effect mobility. Furthermore, it is possible to realize highly reliable transistors.

[0489] It is preferable to use an oxide semiconductor with a low carrier concentration for the transistor. For example, the carrier concentration of an oxide semiconductor is 1 × 10⁻⁶. 17 cm -3 The following is preferably 1 × 10 15 cm -3 More preferably 1 × 10 13 cm -3 More preferably 1 × 10 11 cm -3 More preferably 1 × 10 10 cm -3 It 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.

[0490] High-purity intrinsic or substantially high-purity intrinsic oxide semiconductor films have a low defect level density, which may result in a low trap level density.

[0491] Charges trapped in the trap levels of oxide semiconductors can take a long time to disappear and sometimes behave like fixed charges. Therefore, transistors in which channel formation regions are formed in oxide semiconductors with a high density of trap levels may exhibit unstable electrical properties.

[0492] 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.

[0493] <Impurities> Here, we will explain the effects of various impurities in oxide semiconductors.

[0494] In oxide semiconductors, the presence of silicon and / 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 oxide semiconductor and the concentrations of silicon and carbon near the interface with the oxide semiconductor (concentrations obtained by SIMS) are 2 × 10⁻¹⁰. 18 atoms / cm 3 The following is preferably 2 × 10 17 atoms / cm 3 The following applies:

[0495] When alkali metals or alkaline earth metals are present in oxide semiconductors, they can 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 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:

[0496] 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. This can result in unstable electrical properties of the transistor. Therefore, the nitrogen concentration in 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:

[0497] Hydrogen contained in oxide semiconductors can react with oxygen bonded to metal atoms to form water, potentially creating oxygen vacancies. When hydrogen fills these vacancies, electrons, which act as carriers, can be generated. Furthermore, 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 reduce the hydrogen content in oxide semiconductors as much as possible. Specifically, in oxide semiconductors, the hydrogen concentration obtained by SIMS should be 1 × 10⁻⁶. 20 atoms / cm 3 Less than 1 × 10 19 atoms / cm 3 Less than 5x10 18 atoms / cm 3 Less than 1 × 10 18 atoms / cm 3 Make it less than.

[0498] By using an oxide semiconductor with sufficiently reduced impurities in the channel formation region of a transistor, stable electrical characteristics can be imparted.

[0499] The configuration shown in this embodiment can be used in appropriate combination with the configurations shown in other embodiments and examples.

[0500] (Embodiment 5) This embodiment describes electronic equipment to which a semiconductor device according to one aspect of the present invention can be applied.

[0501] A semiconductor device according to one aspect of the present invention can be applied to the display unit of an electronic device. Therefore, it is possible to realize an electronic device with high display quality, or an extremely high-definition electronic device, or a highly reliable electronic device.

[0502] Electronic devices using a semiconductor device according to one aspect of the present invention include televisions, display devices such as monitors, lighting devices, desktop or notebook personal computers, word processors, and DVDs (Digital Versatile). Examples include image playback devices that play still images or videos stored on recording media such as discs, portable CD players, radios, tape recorders, headphone stereos, stereos, desk clocks, wall clocks, cordless telephone handsets, transceivers, car phones, mobile phones, personal digital assistants, tablet devices, portable game consoles, fixed game machines such as pachinko machines, calculators, electronic organizers, e-book readers, electronic translators, voice input devices, video cameras, digital still cameras, electric shavers, high-frequency heating devices such as microwave ovens, electric rice cookers, electric washing machines, electric vacuum cleaners, water heaters, electric fans, hair dryers, air conditioning equipment such as air conditioners, humidifiers, and dehumidifiers, dishwashers, dish dryers, clothes dryers, futon dryers, electric refrigerators, electric freezers, electric refrigerator-freezers, DNA storage freezers, flashlights, tools such as chainsaws, smoke detectors, and medical equipment such as dialysis machines. Furthermore, industrial equipment such as guide lights, traffic lights, conveyor belts, elevators, escalators, industrial robots, power storage systems, and energy storage devices for power leveling and smart grids can also be included in the category of electronic equipment. In addition, mobile devices propelled by engines using fuel or electric motors using electricity from energy storage devices may also be included in the category of electronic equipment. Examples of such mobile devices include electric vehicles (EVs), hybrid vehicles (HVs) that combine internal combustion engines and electric motors, plug-in hybrid vehicles (PHVs), tracked vehicles in which the tires and wheels of these vehicles are replaced with tracks, motorized bicycles including electric assist bicycles, motorcycles, electric wheelchairs, golf carts, small or large vessels, submarines, helicopters, aircraft, rockets, artificial satellites, space probes, planetary probes, and spacecraft.

[0503] An electronic device according to one aspect of the present invention may have a secondary battery, and it is preferable that the secondary battery can be charged using contactless power transmission.

[0504] Examples of secondary batteries include lithium-ion secondary batteries, nickel-metal hydride batteries, nickel-cadmium batteries, organic radical batteries, lead-acid batteries, air secondary batteries, nickel-zinc batteries, and silver-zinc batteries.

[0505] An electronic device according to one aspect of the present invention may have an antenna. By receiving signals with the antenna, the display unit can display images and information. Furthermore, if the electronic device has an antenna and a secondary battery, the antenna may be used for contactless power transmission.

[0506] An electronic device according to one aspect of the present invention may have sensors (including those with functions to measure force, displacement, position, velocity, acceleration, angular velocity, rotational speed, distance, light, liquid, magnetism, temperature, chemical substances, sound, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, gradient, vibration, odor, or infrared radiation).

[0507] An electronic device according to one aspect of the present invention can have various functions. For example, it can have a function to display various information (still images, videos, text images, etc.) on a display unit, a touch panel function, a function to display a calendar, date or time, a function to execute various software (programs), a wireless communication function, a function to read programs or data recorded on a recording medium, and so on.

[0508] Furthermore, electronic devices having multiple display units may have functions such as displaying image information primarily on one part of the display unit and text information primarily on another part, or displaying a three-dimensional image by displaying images that take parallax into account on multiple display units. Furthermore, electronic devices having an image receiving unit may have functions such as capturing still images or moving images, automatically or manually correcting captured images, saving captured images to a recording medium (external or built into the electronic device), and displaying captured images on a display unit. It should be noted that the functions of an electronic device according to one aspect of the present invention are not limited to these, and it may have a variety of functions.

[0509] A semiconductor device according to one aspect of the present invention can display high-definition images. Therefore, it can be suitably used in portable electronic devices, wearable electronic devices, and e-book readers. For example, it can be suitably used in xR devices such as VR devices or AR devices.

[0510] Figure 36A shows the external appearance of the camera 8000 with the viewfinder 8100 attached.

[0511] The camera 8000 includes a housing 8001, a display unit 8002, operation buttons 8003, a shutter button 8004, etc. A detachable lens 8006 is also attached to the camera 8000. The lens 8006 and the housing of the camera 8000 may be integrated into a single unit.

[0512] Camera 8000 can take an image by pressing the shutter button 8004 or by touching the display unit 8002, which functions as a touch panel.

[0513] The housing 8001 has a mount with electrodes, and in addition to the viewfinder 8100, a strobe device and the like can be connected to it.

[0514] The viewfinder 8100 includes a housing 8101, a display unit 8102, buttons 8103, etc.

[0515] The housing 8101 is attached to the camera 8000 by a mount that engages with the camera 8000's mount. The viewfinder 8100 can display images and other data received from the camera 8000 on the display unit 8102.

[0516] Button 8103 functions as a power button, etc.

[0517] A semiconductor device according to one aspect of the present invention can be applied to the display unit 8002 of the camera 8000 and the display unit 8102 of the viewfinder 8100. The viewfinder 8100 may be built into the camera 8000.

[0518] Figure 36B shows the external appearance of the head-mounted display 8200.

[0519] The head-mounted display 8200 includes a mounting section 8201, lenses 8202, a main unit 8203, a display unit 8204, a cable 8205, etc. The mounting section 8201 also has a built-in battery 8206.

[0520] Cable 8205 supplies power from battery 8206 to main unit 8203. Main unit 8203 is equipped with a wireless receiver and can display received video information on display unit 8204. In addition, main unit 8203 is equipped with a camera and can use information about the user's eyeball or eyelid movements as an input means.

[0521] The attachment unit 8201 may have a function to recognize gaze, provided with multiple electrodes at a position that touches the user and capable of detecting the current flowing in accordance with the user's eye movements. It may also have a function to monitor the user's pulse based on the current flowing through the electrodes. Furthermore, the attachment unit 8201 may have various sensors such as a temperature sensor, a pressure sensor, and an acceleration sensor, and may have a function to display the user's biometric information on the display unit 8204, or a function to change the image displayed on the display unit 8204 in accordance with the user's head movements.

[0522] A semiconductor device according to one aspect of the present invention can be applied to the display unit 8204.

[0523] Figures 36C to 36E show the external appearance of the head-mounted display 8300. The head-mounted display 8300 includes a housing 8301, a display unit 8302, a band-shaped fixing device 8304, and a pair of lenses 8305.

[0524] The user can view the display on the display unit 8302 through the lens 8305. It is preferable to position the display unit 8302 in a curved shape, as this allows the user to experience a greater sense of presence. Furthermore, by viewing different images displayed in different areas of the display unit 8302 through the lens 8305, three-dimensional display using parallax can be performed. Note that the configuration is not limited to a single display unit 8302; two display units 8302 may be provided, with one display unit for each of the user's eyes.

[0525] A semiconductor device according to one aspect of the present invention can be applied to the display unit 8302. The semiconductor device according to one aspect of the present invention can also achieve extremely high resolution. For example, even when the display is magnified and viewed using the lens 8305 as shown in Figure 36E, the pixels are difficult for the user to see. In other words, the display unit 8302 can be used to allow the user to view a highly realistic image.

[0526] Figure 36F shows the external appearance of a goggle-type head-mounted display 8400. The head-mounted display 8400 has a pair of housings 8401, a mounting part 8402, and a cushioning member 8403. A display unit 8404 and a lens 8405 are provided inside each of the pair of housings 8401. By displaying different images on the pair of display units 8404, a three-dimensional display using parallax can be achieved.

[0527] The user can view the display unit 8404 through the lens 8405. The lens 8405 has a focus adjustment mechanism and its position can be adjusted according to the user's eyesight. The display unit 8404 is preferably a square or a horizontally elongated rectangle. This can enhance the sense of realism.

[0528] The mounting portion 8402 is preferably adjustable to the size of the user's face and has plasticity and elasticity to prevent it from slipping off. Furthermore, it is preferable that a part of the mounting portion 8402 has a vibration mechanism that functions as a bone conduction earphone. This eliminates the need for separate audio equipment such as earphones or speakers, allowing users to enjoy video and audio simply by wearing the device. The housing 8401 may also have a function to output audio data via wireless communication.

[0529] The mounting portion 8402 and the cushioning member 8403 are parts that come into contact with the user's face (forehead, cheeks, etc.). By ensuring that the cushioning member 8403 is in close contact with the user's face, light leakage can be prevented, thereby enhancing the sense of immersion. It is preferable to use a soft material for the cushioning member 8403 so that it adheres closely to the user's face when the user wears the head-mounted display 8400. For example, materials such as rubber, silicone rubber, urethane, and sponge can be used. Furthermore, if the surface of a sponge or similar material is covered with cloth, leather (genuine leather or synthetic leather), gaps are less likely to form between the user's face and the cushioning member 8403, effectively preventing light leakage. In addition, using such materials is preferable because it feels good against the skin and does not make the user feel cold when worn in cold seasons. It is preferable that the components that come into contact with the user's skin, such as the cushioning member 8403 or the mounting portion 8402, are removable, as this makes cleaning or replacement easier.

[0530] Figure 37A 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.

[0531] A semiconductor device according to one aspect of the present invention can be applied to the display unit 7000.

[0532] The television device 7100 shown in Figure 37A 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.

[0533] 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.

[0534] Figure 37B 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.

[0535] A semiconductor device according to one aspect of the present invention can be applied to the display unit 7000.

[0536] Figures 37C and 37D show examples of digital signage.

[0537] The digital signage 7300 shown in Figure 37C comprises a housing 7301, a display unit 7000, and a speaker 7303, etc. Furthermore, it may have LED lamps, operation keys (including a power switch or operation switches), connection terminals, various sensors, a microphone, etc.

[0538] Figure 37D 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.

[0539] In Figures 37C and 37D, a semiconductor device according to one embodiment of the present invention can be applied to the display unit 7000.

[0540] 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.

[0541] 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.

[0542] As shown in Figures 37C and 37D, 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. In addition, the display on the display unit 7000 can be switched by operating the information terminal 7311 or information terminal 7411.

[0543] The digital signage 7300 or digital signage 7400 can also be used to run games using the screen of the information terminal 7311 or information terminal 7411 as the control device (controller). This allows a large number of users to participate in and enjoy the game simultaneously.

[0544] The information terminal 7550 shown in Figure 37E includes a housing 7551, a display unit 7552, a microphone 7557, a speaker unit 7554, a camera 7553, and an operation switch 7555. A semiconductor device according to one aspect of the present invention can be applied to the display unit 7552. The display unit 7552 also functions as a touch panel. Furthermore, the information terminal 7550 is equipped with an antenna, battery, etc. inside the housing 7551. The information terminal 7550 can be used, for example, as a smartphone, mobile phone, tablet information terminal, tablet personal computer, e-book reader, etc.

[0545] Figure 37F shows an example of a wristwatch-type information terminal. The information terminal 7660 includes a housing 7661, a display unit 7662, a band 7663, a buckle 7664, an operation switch 7665, and input / output terminals 7666. The information terminal 7660 also includes an antenna and battery inside the housing 7661. The information terminal 7660 can run various applications such as mobile phone calls, email, document viewing and creation, music playback, internet communication, and computer games.

[0546] The display unit 7662 is equipped with a touch sensor and can be operated by touching the screen with a finger or stylus. For example, an application can be launched by touching the icon 7667 displayed on the display unit 7662. The operation switch 7665 can have various functions, including setting the time, turning the power on and off, turning wireless communication on and off, activating and deactivating silent mode, and activating and deactivating power saving mode. For example, the functions of the operation switch 7665 can also be configured by the operating system built into the information terminal 7660.

[0547] The information terminal 7660 is capable of performing standardized short-range wireless communication. For example, it can communicate with a wireless communication-enabled headset to make hands-free calls. The information terminal 7660 is also equipped with an input / output terminal 7666, which allows it to send and receive data with other information terminals. It can also be charged via the input / output terminal 7666. However, charging may be performed wirelessly without using the input / output terminal 7666.

[0548] Figure 38A shows the exterior of the automobile 9700. Figure 38B shows the driver's seat of the automobile 9700. The automobile 9700 includes a body 9701, wheels 9702, dashboard 9703, lights 9704, etc. A display device according to one aspect of the present invention can be used in the display unit of the automobile 9700. For example, a display device according to one aspect of the present invention can be provided in the display units 9710 to 9715 shown in Figure 38B.

[0549] Display units 9710 and 9711 are display devices installed on the windshield of an automobile. In one aspect of the present invention, the electrodes of the display device are made of a light-transmitting conductive material, thereby creating a so-called see-through display device that allows the other side to be seen through. A see-through display device does not obstruct the driver's view when the automobile 9700 is in operation. Therefore, the display device according to one aspect of the present invention can be installed on the windshield of the automobile 9700. When the display device is equipped with transistors for driving the display device, it is preferable to use light-transmitting transistors such as organic transistors made of organic semiconductor materials or transistors made of oxide semiconductors.

[0550] The display unit 9712 is a display device installed in the pillar. For example, by displaying images from an imaging device installed on the vehicle body on the display unit 9712, the field of view obstructed by the pillar can be compensated for. The display unit 9713 is a display device installed in the dashboard. For example, by displaying images from an imaging device installed on the vehicle body on the display unit 9713, the field of view obstructed by the dashboard can be compensated for. In other words, by displaying images from an imaging device installed on the outside of the vehicle, blind spots can be compensated for and safety can be enhanced. Furthermore, by displaying images that compensate for parts that are not visible, safety checks can be performed more naturally and without discomfort.

[0551] Figure 39 shows the interior of a car with bench seats for the driver and passenger. Display unit 9721 is a display device installed in the door. For example, by displaying images from an imaging device installed on the vehicle body on display unit 9721, the view obstructed by the door can be compensated for. Display unit 9722 is a display device installed on the steering wheel. Display unit 9723 is a display device installed in the center of the seat surface of the bench seat.

[0552] Display units 9714, 9715, or 9722 can provide various information by displaying navigation information, driving speed, engine RPM, mileage, fuel level, gear status, air conditioning settings, etc. Furthermore, the display items and layout displayed on the display units can be changed as needed to suit the user's preferences. The above information can also be displayed on display units 9710 to 9713, 9721, and 9723. Additionally, display units 9710 to 9715 and 9721 to 9723 can also be used as lighting devices.

[0553] The configuration shown in this embodiment can be used in appropriate combination with the configurations shown in other embodiments and examples. [Examples]

[0554] In this example, a sample having multiple transistors as shown in the previous embodiment was prepared, and the electrical characteristics of the transistors, the variation in the electrical characteristics of the transistors, and the reliability of the transistors were evaluated.

[0555] The sample used in this embodiment has a transistor similar to the transistor 500 shown in Figures 34A to 34C. The design values ​​for the sample transistor 500 were a channel length of 200 nm and a channel width of 130 nm. In the sample, three transistors 500 are connected in series, forming a triple-gate structure (see transistor 180B in Figure 5B). In the sample of this embodiment, multiple triple-gate structures composed of three transistors 500 are provided.

[0556] [Structure of Transistor 500] The structure of transistor 500 included in the sample will be described below with reference to Figure 34B.

[0557] As shown in Figure 34B, the transistor 500 comprises an insulator 514, an insulator 516 placed on top of the insulator 514, a conductor 505 placed embedded in the insulator 516, an insulator 522 placed on top of the insulator 516 and the conductor 505, an insulator 524 placed on top of the insulator 522, a metal oxide 531 placed on top of the insulator 524, and conductors 542a and conductors placed spaced apart from each other on top of the metal oxide 531. The material comprises 542b, insulators 554 and 580 disposed on conductors 542a and 542b with an opening formed between conductors 542a and 542b, conductor 560 disposed within the opening, insulator 550 disposed between metal oxide 531, conductor 542a, conductor 542b, insulator 580, and conductor 560, and insulator 574 disposed on insulator 580, insulator 550, and conductor 560.

[0558] The insulator 514 is a laminated film consisting of a silicon nitride film with a thickness of 60 nm and an aluminum oxide film with a thickness of 40 nm on the silicon nitride film. The silicon nitride film and the aluminum oxide film were deposited using the sputtering method.

[0559] The insulator 516 is a silicon oxide film deposited using the sputtering method.

[0560] The conductor 505 in this embodiment has a structure that includes conductors 505a and 505b, but does not include conductor 505c. Conductor 505a is a laminated film of a tantalum nitride film with a thickness of 40 nm and a titanium nitride film with a thickness of 20 nm on the tantalum nitride film. The tantalum nitride film was deposited by sputtering, and the titanium nitride film was deposited by CVD. Conductor 505b is a tungsten film deposited by CVD.

[0561] Insulator 522 is a hafnium oxide film with a thickness of 20 nm, deposited by the ALD method.

[0562] Insulator 524 is a silicon oxide film with a thickness of 20 nm, deposited by sputtering.

[0563] The metal oxide 531 in this embodiment has a single-layer structure, similar to the semiconductor layer 321 shown in Figure 31. In other words, the metal oxide 531 is a single-layer structure consisting only of metal oxide 531a. The metal oxide 531a is an In-Ga-Zn oxide film with a thickness of 20 nm. The metal oxide 531a was deposited by sputtering using a target having a composition close to In:Ga:Zn = 1:3:4 [atomic ratio].

[0564] Conductors 542a and 542b are tantalum nitride films with a thickness of 20 nm, deposited by sputtering. In addition, an aluminum oxide film with a thickness of 5 nm, also deposited by sputtering, is superimposed on conductors 542a and 542b.

[0565] The insulator 554 is a laminated film consisting of a 5 nm thick aluminum oxide film and a 5 nm thick silicon nitride film on the aluminum oxide film. The silicon nitride film was deposited using the ALD method, and the aluminum oxide film was deposited using the sputtering method.

[0566] Insulator 580 is a silicon oxide film deposited using the sputtering method.

[0567] The insulator 550 is a laminated film consisting of a 1 nm thick aluminum oxide film, a 10 nm thick silicon oxide film on the aluminum oxide film, a 1.5 nm thick hafnium oxide film on the silicon oxide film, and a 1 nm thick silicon nitride film on the hafnium oxide film. The aluminum oxide film, silicon oxide film, hafnium oxide film, and silicon nitride film were deposited using the ALD method.

[0568] The conductor 560 in this embodiment comprises conductor 560a and conductor 560b. Conductor 560a is a titanium nitride film with a thickness of 5 nm. The titanium nitride film was deposited by CVD. Conductor 560b is a tungsten film deposited by CVD.

[0569] Insulator 574 is an aluminum oxide film with a thickness of 40 nm, deposited by sputtering.

[0570] Electrical characteristics and reliability evaluations were performed on samples containing multiple transistors 500 with the structure described above.

[0571] [Electrical Characteristics Evaluation] The electrical characteristics of a triple-gate transistor (transistor 180B) contained in the sample were evaluated. Here, the Id-Vg characteristic was measured. For the Id-Vg characteristic measurement, the drain voltage Vd was set to 0.1V or 1.2V, the source voltage Vs and back gate voltage Vbg to 0V, and the top gate voltage Vg was swept from -4.0V to +4.0V in 0.1V steps. The measurement was performed at room temperature.

[0572] Figure 40A shows the Id-Vg characteristics of the transistor included in the sample. In Figure 40A, the horizontal axis represents the gate voltage (Vg [V]), and the vertical axis represents the drain current (Id [A]). In Figure 40A, the Id value when the drain voltage Vd is 0.1V is shown by a solid line, and the Id value when the drain voltage Vd is 1.2V is shown by a dashed line.

[0573] As shown in Figure 40A, the transistor included in the sample exhibited normally-off characteristics, and its switching characteristics were confirmed. Furthermore, as shown in Figure 40A, the off-current of the transistor was below the lower limit of measurement and was remarkably low.

[0574] Next, the Id-Vg characteristics of triple-gate transistors (transistor 180B) were measured, and the variability of the threshold voltage (Vth [V]), Ion [A], and S value (SS [V / dec]) was evaluated. The Id-Vg characteristics were measured for 1060 triple-gate transistors (1060 transistors 180B). The threshold voltage Vth is the value of the top gate voltage Vg at which Id = 1 pA. Ion is the value of the drain current Id at Vg = Vth + 2.5 V. The S value is the value of Vg required for Id to change by one order of magnitude in the subthreshold region, with Vd set to 1.2 V.

[0575] Figure 40B shows the cumulative probability of the threshold voltage of the transistors contained in the sample. In Figure 40B, the horizontal axis represents the threshold voltage (Vth [V]), and the vertical axis represents the cumulative probability (Percentile [%]).

[0576] From Figure 40B, the standard deviation σ of the transistor's Vth was 161mV.

[0577] Figure 41A shows the cumulative probability of Ions in the transistors contained in the sample. In Figure 41A, the horizontal axis represents Ion [A] and the vertical axis represents the cumulative probability (Percentile [%]).

[0578] From Figure 41A, the standard deviation σ of the transistor's Ion is 1.16 × 10⁻⁶. -8 The result was A. Also, the average Ion value of 1060 transistors was 3.19 × 10⁶. -8 The result was A. Therefore, σ / average = 36%.

[0579] Figure 41B shows the cumulative probability of the S value of transistors contained in the sample. In Figure 41B, the horizontal axis represents the S value (SS [V / dec]), and the vertical axis represents the cumulative probability (Percentile [%]).

[0580] From Figure 41B, the standard deviation σ of the transistor's S value was 48 mV / dec.

[0581] As shown above, the electrical characteristics of the transistors in the sample according to this embodiment showed little variation. By using these transistors as driving transistors for a display device, a display device with good display quality can be provided.

[0582] [Reliability evaluation] Next, the reliability of triple-gate transistors was evaluated by applying stress equivalent to either white or black indication. For the white indication stress, the substrate temperature was set to 125°C, and Vg=+1.90V and Vd=+3.80V were applied. For the black indication stress, the substrate temperature was set to 125°C, and Vg=0V and Vd=+9.00V were applied. In both stress tests, the maximum stress duration was 90 hours. Also, in both stress tests, Vs=0V and Vbg=0V were set. In the following, the tests applying white indication stress and the tests applying black indication stress may be referred to simply as stress tests.

[0583] Reliability was evaluated by measuring the threshold voltage Vth, S value (SS), field-effect mobility μFE, and Ion, and taking the difference between the values ​​before and after the stress test. These differences are denoted as ΔVth, ΔSS, ΔμFE, and ΔIon. The maximum value of the field-effect mobility μFE at Vd = 0.1V was used. The field-effect mobility μFE is obtained by solving the equation for the field-effect mobility μFE in the gradient channel approximation.

[0584] Figure 42A shows the time dependence of the threshold voltage difference. In Figure 42A, the horizontal axis represents stress time (Time [hr]), and the vertical axis represents the threshold voltage difference (ΔVth [mV]). In Figure 42A, white circles represent graphs of stress tests shown in white, and black circles represent graphs of stress tests shown in black.

[0585] As shown in Figure 42A, under the white-indicated stress, ΔVth was approximately +100mV or less. Furthermore, under the black-indicated stress, a negative change in ΔVth was observed, but the absolute value of ΔVth was smaller than under the white-indicated stress. Therefore, it is presumed that even when the transistor of this embodiment is used as a drive transistor that continuously supplies current for a long period of time, the degradation of the threshold voltage will be small.

[0586] Figure 42B shows the time dependence of the difference in S values. In Figure 42B, the horizontal axis represents stress time (Time [hr]), and the vertical axis represents the difference in S values ​​(ΔSS [V / dec]). In Figure 42B, white circles represent graphs of stress tests shown in white, and black circles represent graphs of stress tests shown in black.

[0587] As shown in Figure 42B, there was almost no deterioration in the S value under both white-displayed and black-displayed stress.

[0588] Figure 43A shows the time dependence of the difference in field-effect mobility. In Figure 43A, the horizontal axis represents stress time (Time [hr]), and the vertical axis represents the difference in field-effect mobility (ΔμFE [cm]). 2This represents [Vs]). Also, in Figure 43A, the white circles represent graphs of stress tests shown in white, and the black circles represent graphs of stress tests shown in black.

[0589] As shown in Figure 43A, there was almost no degradation of field-effect mobility under the white-displayed stress and the black-displayed stress.

[0590] Figure 43B shows the time dependence of the Ion difference. In Figure 43B, the horizontal axis represents stress time (Time [hr]), and the vertical axis represents the Ion difference (ΔIon [%]). The Ion difference is shown as a percentage with the initial state set to 100%. In Figure 43B, white circles represent graphs of stress tests shown in white, and black circles represent graphs of stress tests shown in black.

[0591] Figure 43B shows that Ion increased under both the white-indicated and black-indicated stresses. Here, Ion is the value at Vg = Vth + 2.5V, and it is presumed to reflect the change in Vth during the stress test.

[0592] As described above, in stress tests, the field-effect mobility and S value hardly deteriorate. Therefore, if a circuit configuration is used in the pixel circuit that corrects fluctuations in the threshold voltage, the display device according to the present invention can provide uniform display over a long period of time.

[0593] Next, the Id-Vd characteristics were measured before and after a 60-hour stress test. For the Id-Vg characteristic measurement, the top gate voltage Vg was set to 1.9V, the source voltage Vs and back gate voltage Vbg to 0V, and the drain voltage Vd was swept from 0V to +5.0V in 0.1V steps. The measurement was performed at a substrate temperature of 125°C.

[0594] Figure 44A shows the Id-Vd measurement results before and after stress (indicated in white), and Figure 44B shows the Id-Vd measurement results before and after stress (indicated in black). In Figures 44A and 44B, the horizontal axis represents drain voltage (Vd [V]), and the vertical axis represents drain current (Id [A]). In Figures 44A and 44B, Id before the stress test is shown by a solid line, and Id after the stress test is shown by a dashed line.

[0595] As shown in Figure 44A, after stress (indicated in white), Id at Vd=3.8V increased by approximately 17.7%. Furthermore, as shown in Figure 44B, after stress (indicated in black), Id at Vd=3.8V increased by approximately 0.4%.

[0596] As shown in Figures 44A and 44B, in the saturation region, which is the operating region where Vd is large, Id remained almost constant. Therefore, the transistor according to this embodiment can suitably drive a light-emitting device as a constant current source circuit. [Examples]

[0597] In this embodiment, a sample corresponding to the capacitive element 73 shown in the previous embodiment was prepared, and the pattern defects of the resist mask were evaluated.

[0598] <Sample preparation> First, a substrate was prepared. A silicon substrate with a transistor and an insulating layer was used as the substrate. This substrate corresponds to the configuration between substrate 69 and insulating layer 288 shown in Figure 2.

[0599] Next, a first tungsten film with a thickness of 50 nm was formed on the substrate by sputtering.

[0600] Next, the first tungsten film was processed to form a plurality of island-shaped tungsten layers. These tungsten layers correspond to the conductive layer 87 shown in the previous embodiment.

[0601] Next, an insulating layer was formed on the tungsten layer. As the insulating layer, an aluminum oxide film with a thickness of 14 nm and a silicon oxynitride film with a thickness of 7 nm were formed in that order. The aluminum oxide film was formed by the ALD method, and the silicon oxynitride film was formed by the CVD method. This insulating layer corresponds to the insulating layer 91 shown in the previous embodiment.

[0602] Next, a second tungsten film with a thickness of 30 nm was formed on the insulating layer by sputtering. This second tungsten film corresponds to the conductive layer 89 shown in the previous embodiment.

[0603] Next, a first organic film with a thickness of 150 nm was formed on the second tungsten film by spin coating. A Spin On Carbon (SOC) film was used as the first organic film.

[0604] Next, a second organic film with a thickness of 40 nm was formed on the first organic film by spin coating. A Spin-On-Glass (SOG) film was used as the second organic film.

[0605] Next, a resist material was applied to the second organic film, and multiple resist masks were formed by photolithography using an electron beam. A negative-type resist material was used, and the thickness of the resist mask was set to 100 nm. This resist mask corresponds to the resist mask used to form the conductive layer 89 shown in the previous embodiment. The area ratio of the resist masks was varied between samples. The area ratio of the resist masks for sample 1 was set to 21%, and the area ratio of the resist masks for sample 2 was set to 49%.

[0606] <Observation with an optical microscope> Next, each sample was observed using an optical microscope. The optical microscope image of sample 1 is shown in Figure 45A. The optical microscope image of sample 2 is shown in Figure 45B. Figures 45A and 45B are bright-field images of reflection, respectively. As shown in Figure 45A, it was confirmed that sample 1 had a pattern defect in the resist mask (PR) (see the area indicated by the dashed line in Figure 45A). On the other hand, no pattern defect in the resist mask (PR) was observed in sample 2.

[0607] We confirmed that increasing the area ratio of the resist mask reduces pattern defects in the resist mask. [Explanation of Symbols]

[0608] C11: Capacitive element, C12: Capacitive element, C13: Capacitive element, DL: Wiring, GLa: Wiring, GLB: Wiring, GLC: Wiring, M11: Transistor, M12: Transistor, M13: Transistor, M14: Transistor, M15: Transistor, M16: Transistor, M17: Transistor, ND11: Node, ND12: Node, ND13: Node, ND14: Node, 10: Display device, 23: CPU, 24: GPU, 25: Memory circuit section, 29: Input / output terminal section, 40: Layer, 50: Layer, 51A: Pixel circuit, 51B: Pixel circuit, 51: Pixel circuit, 60: Layer, 61a: Light-emitting device, 61B: Light-emitting device, 61b: Light-emitting device, 61c: Light-emitting device, 61G: Light-emitting device, 61R: Light-emitting device, 61W: Light-emitting device, 61: Light-emitting device, 63A: Conductive layer, 63B: Conductive layer, 63C: Conductive layer, 63: Conductive layer, 65: EL layer, 67: Conductive layer, 69: Substrate, 71DM: Dummy transistor, 71: Transistor, 73: Capacitive element, 75A: Wiring, 75DMa: Conductive layer, 75DMb: Dummy layer, 75: Conductive layer, 77a: Insulating layer, 77b: Insulating layer, 79DM: Semiconductor layer, 79: Semiconductor layer, 81DM: Insulating layer, 81: Insulating layer, 83DM: Conductive layer, 83: Conductive layer, 85DM: Conductive layer, 85: Conductive layer, 87A: Conductive layer, 87B: Conductive layer, 87DM: Dummy layer, 87: Conductive layer, 89DM: Dummy layer, 89: Conductive layer, 91: Insulating layer, 97A: Resist mask, 97B: Resist mask, 97DM: Resist mask, 97: Resist mask, 100A: Semiconductor device, 100B: Semiconductor device, 101: Wiring, 102: Wiring, 103A: Conductive layer, 103B: Conductive layer, 103C: Conductive layer, 103D: Conductive layer, 103: Wiring, 104: Wiring, 105A: Conductive layer, 105B : Conductive layer, 105C: Conductive layer, 105D: Conductive layer, 105E: Conductive layer, 105F: Conductive layer, 105G: Conductive layer, 105H: Conductive layer, 105I: Conductive layer, 105J: Conductive layer, 105K: Conductive layer, 105L: Conductive layer, 106A: Conductive layer, 106B: Conductive layer, 107A: Conductive layer, 107B: Conductive layer, 107C: Conductive layer, 107D: Conductive layer, 107DMa: Conductive layer, 107DMb: Conductive layer, 109DMa: Dummy transistor, 109DMb: Dummy transistor, 110A: Contact hole, 110B: Contact hole, 110C: Contact hole,110D: Contact hole, 110E: Contact hole, 110F: Contact hole, 110G: Contact hole, 110H: Contact hole, 110I: Contact hole, 110J: Contact hole, 110K: Contact hole, 110L: Contact hole, 110M: Contact hole, 110N: Contact hole, 110P: Contact hole, 110Q: Contact hole, 110R: Contact hole, 110S: Contact hole, 110T: Contact hole, 110V: Contact hole, 110W: Contact hole 110X: Contact hole, 111A: Semiconductor layer, 111B: Semiconductor layer, 111C: Semiconductor layer, 111D: Semiconductor layer, 111DMa: Semiconductor layer, 111E: Semiconductor layer, 111F: Semiconductor layer, 113A: Conductive layer, 113B: Conductive layer, 113C: Conductive layer, 113D: Conductive layer, 115A: Contact hole, 115B: Contact hole, 115C: Contact hole, 115D: Contact hole, 115E: Contact hole, 115F: Contact hole, 115G: Contact hole, 115H: Contact hole, 115I: Contact hole, 115J: Contact hole, 117A: Contact hole, 117B: Contact hole, 117C: Contact hole, 119: Wiring, 121A: Contact hole, 121B: Contact hole, 121C: Contact hole, 171: Conductive layer, 172a: EL layer, 172B: EL layer, 172b: EL layer, 172G: EL layer, 172R: EL layer, 172W: EL layer, 172: EL layer, 173: Conductive layer, 174: Common layer, 175B: Optical, 175G: Optical, 175R: Optical, 180A: Transistor, 180B: Transistor, 180C: Transistor, 23 0B: Sub-pixel, 230C: Sub-pixel, 230G: Sub-pixel, 230M: Sub-pixel, 230R: Sub-pixel, 230W: Sub-pixel, 230Y: Sub-pixel, 230: Pixel, 231: First drive circuit section, 232: Second drive circuit section, 235: Display area, 241: Conductive layer, 243: Insulating layer, 245: Conductive layer, 246: Capacitive element, 251: Conductive layer, 252: Conductive layer, 254: Insulating layer, 255: Insulating layer, 256: Plug, 261: Insulating layer, 262: Insulating layer, 263: Insulating layer, 264B: Coloring layer, 264G: Coloring layer, 264R: Coloring layer, 264: Insulating layer, 265: Insulating layer, 266: Plug,270: Insulating layer, 271: Protective layer, 272: Insulating layer, 273: Protective layer, 274A: Plug, 274a: Conductive layer, 274B: Plug, 274b: Conductive layer, 274C: Plug, 274D: Plug, 274: Plug, 275: Region, 276: Insulating layer, 277: Microlens array, 278: Insulating layer, 279DM: Dummy layer, 279: Wiring, 281DM: Dummy layer, 281: Wiring, 283: Insulating layer, 284: Insulating layer, 285: Insulating layer, 286: Insulating layer, 287: Insulating layer, 288: Insulating layer, 289: Insulating layer, 290: Insulating layer, 291: Insulating layer, 293: Insulating layer, 301A: Substrate, 301B: Substrate, 301: Substrate, 310A: Transistor, 310B: Transistor, 310: Transistor, 311: Conductive layer, 312: Low resistance region, 313: Insulating layer, 314: Insulating layer, 315: Element isolation layer, 320: Transistor, 321: Semiconductor layer, 323: Insulating layer, 324: Conductive layer, 325: Conductive layer, 326: Insulating layer, 327: Conductive layer, 328: Insulating layer, 329: Insulating layer, 331: Substrate, 332: Insulating layer, 341: Conductive layer, 342: Conductive layer, 343: Plug, 363: Insulating layer, 415: Protective layer, 419: Resin layer, 420: Substrate, 500: Transistor, 505a: Conductor, 505b: Conductor, 505c: Conductor, 505: Conductor, 514: Insulator, 516: Insulator, 522: Insulator, 524: Insulator, 531a: Metal oxide, 531b: Metal oxide, 531c: Metal oxide, 531: Metal oxide, 541a: Insulator, 541b: Insulator, 541: Insulator, 542a: Conductor, 542b: Conductor, 542: Conductor, 545a: Conductor, 545b: Conductor, 545: Conductor, 550: Insulator, 554: Insulator, 560a: Conductor, 560b: Conductor, 560: Conductor, 574: Insulator , 580: insulator, 581: insulator, 4411: light-emitting layer, 4412: light-emitting layer, 4413: light-emitting layer, 4420: layer, 4430: layer, 7000: display unit, 7100: television equipment, 7101: housing, 7103: stand, 7111: remote control unit, 7200: notebook personal computer, 7211: housing, 7212: keyboard, 7213: pointing device, 7214: external connection port, 7300: digital signage, 7301: housing, 7303: speaker, 7311: information terminal, 7400: digital signage, 7401: column,7411: Information terminal, 7550: Information terminal, 7551: Housing, 7552: Display unit, 7553: Camera, 7554: Speaker unit, 7555: Operation switch, 7557: Microphone, 7660: Information terminal, 7661: Housing, 7662: Display unit, 7663: Band, 7664: Buckle, 7665: Operation switch, 7666: Input / output terminal, 7667: Icon, 8000: Camera, 8001: Housing, 8002: Display unit, 8003: Operation button, 8004: Shutter button, 8006: Lens, 8100: Viewfinder, 8101: Housing, 8102: Display unit, 8103: Button, 8200: Head-mounted display, 8201: Mounting unit, 8202 :Lens, 8203:Main unit, 8204:Display unit, 8205:Cable, 8206:Battery, 8300:Head-mounted display, 8301:Housing, 8302:Display unit, 8304:Fixing device, 8305:Lens, 8400:Head-mounted display, 8401:Housing, 8402:Mounting part, 8403:Cushioning material, 8404:Display unit, 8405:Lens, 9700:Automobile, 9701:Vehicle body, 9702:Wheels, 9703:Dashboard, 9704:Lights, 9710:Display unit, 9711:Display unit, 9712:Display unit, 9713:Display unit, 9714:Display unit, 9715:Display unit, 9721:Display unit, 9722:Display unit, 9723:Display unit,

Claims

1. It has a display unit, The display unit has a plurality of sub-pixels, Each of the aforementioned subpixels comprises a first transistor, a second transistor, a first capacitive element, a second capacitive element, a third capacitive element, a first insulating layer, and wiring. The first transistor is electrically connected to the second transistor, the first capacitive element, the second capacitive element, and the third capacitive element. Each of the first to third capacitive elements comprises a first conductive layer, a second conductive layer, and a second insulating layer sandwiched between the first conductive layer and the second conductive layer. The first insulating layer is provided on the first transistor and the second transistor, The first conductive layer of the first to third capacitive elements and the wiring are each provided on the first insulating layer. In a top view, the area of ​​the first conductive layer of the second capacitive element is at least twice the area of ​​the first conductive layer of the first capacitive element. A semiconductor device in which, when viewed from above, the area of ​​the first conductive layer of the third capacitive element is at least twice the area of ​​the first conductive layer of the first capacitive element.

2. It has a display unit, The display unit has a plurality of sub-pixels and a substrate. Each of the aforementioned subpixels comprises a first transistor, a second transistor, a third transistor, a first capacitive element, a second capacitive element, a third capacitive element, a first insulating layer, and wiring. Each of the first to third transistors is provided on the substrate, The first transistor is electrically connected to the second transistor, the first capacitive element, the second capacitive element, and the third capacitive element. The third transistor described above is electrically floating, Each of the first to third capacitive elements comprises a first conductive layer, a second conductive layer, and a second insulating layer sandwiched between the first conductive layer and the second conductive layer. The first insulating layer is provided on the first transistor and the second transistor, The first conductive layer of the first to third capacitive elements and the wiring are each provided on the first insulating layer. In a top view, the area of ​​the first conductive layer of the second capacitive element is at least twice the area of ​​the first conductive layer of the first capacitive element. In a top view, the area of ​​the first conductive layer of the third capacitive element is at least twice the area of ​​the first conductive layer of the first capacitive element. Each of the first to third transistors is a semiconductor device having a semiconductor layer.

3. It has a display unit, The display unit has a plurality of sub-pixels and a substrate. Each of the aforementioned subpixels comprises a first transistor, a second transistor, a third transistor, a first capacitive element, a second capacitive element, a third capacitive element, a first insulating layer, and wiring. Each of the first to third transistors is provided on the substrate, The first transistor is electrically connected to the second transistor, the first capacitive element, the second capacitive element, and the third capacitive element. The third transistor described above is electrically floating, Each of the first to third capacitive elements comprises a first conductive layer, a second conductive layer, and a second insulating layer sandwiched between the first conductive layer and the second conductive layer. The first insulating layer is provided on the first transistor and the second transistor, The first conductive layer of the first to third capacitive elements and the wiring are each provided on the first insulating layer. In a top view, the area of ​​the first conductive layer of the second capacitive element is at least twice the area of ​​the first conductive layer of the first capacitive element. In a top view, the area of ​​the first conductive layer of the third capacitive element is at least twice the area of ​​the first conductive layer of the first capacitive element. Each of the first to third transistors has a semiconductor layer, A semiconductor device having a semiconductor layer of the third transistor that shares a region with the semiconductor layer of the first transistor.

4. In any one of claims 1 to 3, A semiconductor device in which, when viewed from above, the ratio of the total area of ​​the first conductive layer of the first to third capacitive elements and the wiring to the area of ​​the sub-pixel is 10% or more.

Images