Semiconductor device

Abstract

Provided is a novel semiconductor device. The semiconductor device includes a drive transistor having a back gate, a first switch, a second switch, a first capacitive element, a second capacitive element, a diode, and a light-emitting element. The first switch is connected to the gate of the drive transistor, and the second switch and the diode are connected to the back gate of the drive transistor. One of the source and drain of the drive transistor is connected to first wiring, and the other of the source and drain is connected to the anode of the light-emitting element. The second switch is in a conductive state during a period in which a high potential is being supplied to the first wiring, and is in a non-conductive state during a period in which a low potential is being supplied to the first wiring.

Description

Semiconductor equipment

[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. The technical field of the invention disclosed herein relates to a product, a method, or a method of manufacture. Alternatively, one aspect of the present invention relates to a process, a machine, a manufacture, or a composition of matter. More specifically, examples of the technical field of one aspect of the present invention disclosed herein include semiconductor devices, display devices, light-emitting devices, energy storage devices, memory devices, methods for driving them, or methods for manufacturing them.

[0003] In recent years, research and development of self-emissive display devices using light-emitting diodes (LEDs) and other light-emitting elements as pixels has been actively pursued. In particular, active-matrix display devices using organic EL (Electroluminescence) elements as light-emitting elements are attracting attention. Generally, the pixels of an active-matrix display device consist of a light-emitting element and a pixel circuit. The pixel circuit also includes transistors (drive transistors) that control the amount of current supplied to the light-emitting element according to the video signal.

[0004] The luminescence brightness of a light-emitting element is determined by the magnitude of the drain current of the drive transistor. Therefore, if there is variation in the electrical characteristics of the drive transistors among multiple pixels that make up the screen of a display device, even if the same video signal is supplied to multiple pixels, differences in the luminescence brightness of each pixel will occur. In particular, variations in the threshold voltage (also written as "Vth") have a significant impact on the degradation of the display quality of the display device. Patent Document 1 describes a circuit configuration for reducing variations in the threshold voltage of the drive transistor.

[0005] Furthermore, improvements in resolution, detail, and other aspects are required to enhance the display quality of display devices.

[0006] Japanese Patent Publication No. 2013-137498

[0007] In order to improve the resolution, fineness, etc. of a display device and enhance the display quality, it is necessary to reduce the occupied area of a semiconductor device that functions as a pixel circuit. In order to realize a pixel circuit with a smaller occupied area, it is necessary to configure a semiconductor device that functions as a pixel circuit with a smaller number of circuit elements. Further, in order to improve the resolution, fineness, etc. of a display device, reduction of the number of wirings connected to the pixel circuit is also required.

[0008] One aspect of the present invention has an object to provide a semiconductor device in which the influence of characteristic variations is reduced. Or, one aspect of the present invention has an object to provide a semiconductor device with low power consumption. Or, one aspect of the present invention has an object to provide a semiconductor device with good reliability. Or, one aspect of the present invention has an object to provide a novel semiconductor device. Or, one aspect of the present invention has an object to provide a display device with high display quality. Or, one aspect of the present invention has an object to provide a novel display device.

[0009] Note that the description of the above problems does not prevent the existence of other problems. Other problems can be naturally found from the descriptions in the specification, drawings, claims, etc., and other problems can be extracted from the descriptions in the specification, drawings, claims, etc. Note that one aspect of the present invention is not required to solve all of these problems (the above problems and other problems).

[0010] (1) One aspect of the present invention includes a first to third transistors, first and second capacitor elements, and a light-emitting element. A first terminal of the first transistor is electrically connected to a first wiring. A second terminal of the first transistor is electrically connected to a first terminal of the first capacitor element, a first terminal of the second capacitor element, and a first terminal of the light-emitting element. A gate of the first transistor is electrically connected to a first terminal of the second transistor and a second terminal of the first capacitor element. A back gate of the first transistor is electrically connected to a first terminal of the third transistor and a second terminal of the second capacitor element. A gate of the third transistor is electrically connected to a second terminal of the third transistor. A back gate of the third transistor is electrically connected to the first wiring. The third transistor is a p-type transistor.

[0011] Further, in (1), each of the first transistor and the second transistor is preferably a transistor including an oxide semiconductor in a semiconductor layer. Further, the third transistor preferably includes silicon in the semiconductor layer.

[0012] (2) Another aspect of the present invention is a semiconductor device including a transistor, a first switch, a second switch, a first capacitor, a second capacitor, a light-emitting element, and a diode, wherein a first terminal of the transistor is electrically connected to a first wiring, a second terminal of the transistor is electrically connected to a first terminal of the first capacitor, a first terminal of the second capacitor, and a first terminal of the light-emitting element, a gate of the transistor is electrically connected to a first terminal of the first switch and a second terminal of the first capacitor, a back gate of the transistor is electrically connected to a first terminal of the second switch, a second terminal of the second capacitor, and an anode of the diode, and a second terminal of the second switch is electrically connected to a cathode of the diode.

[0013] (3) Another aspect of the present invention is a semiconductor device including first to fourth transistors, first and second capacitors, and a light-emitting element, wherein a first terminal of the first transistor is electrically connected to a first wiring, a second terminal of the first transistor is electrically connected to a first terminal of the first capacitor, a first terminal of the second capacitor, a first terminal of the fourth transistor, and a first terminal of the light-emitting element, a gate of the first transistor is electrically connected to a first terminal of the second transistor and a second terminal of the first capacitor, a back gate of the first transistor is electrically connected to a first terminal of the third transistor and a second terminal of the second capacitor, a gate of the third transistor is electrically connected to a second terminal of the third transistor, a back gate of the third transistor is electrically connected to the first wiring, a gate of the second transistor is electrically connected to a third wiring, a gate of the fourth transistor is electrically connected to the third wiring, and the third transistor is a p-type transistor.

[0014] Further, in (3), each of the first transistor, the second transistor, and the fourth transistor is preferably a transistor including an oxide semiconductor in a semiconductor layer. Further, the third transistor preferably includes silicon in the semiconductor layer.

[0015] (4) Another aspect of the present invention is a semiconductor device comprising a transistor, a first switch, a second switch, a third switch, a first capacitance element, a second capacitance element, a light-emitting element, and a diode, wherein the first terminal of the transistor is electrically connected to a first wiring, the second terminal of the transistor is electrically connected to the first terminal of the first capacitance element, the first terminal of the second capacitance element, the first terminal of the third switch, and the first terminal of the light-emitting element, the gate of the transistor is electrically connected to the first terminal of the first switch and the second terminal of the first capacitance element, the back gate of the transistor is electrically connected to the first terminal of the second switch, the second terminal of the second capacitance element, and the anode of the diode, and the second terminal of the second switch is electrically connected to the cathode of the diode.

[0016] Furthermore, in (4), it is preferable that the third switch is ON when the first switch is ON, and that the third switch is OFF when the first switch is OFF.

[0017] Furthermore, in (2) and (4), it is preferable that the transistor includes an oxide semiconductor in its semiconductor layer.

[0018] Furthermore, in (1) to (4), the oxide semiconductor preferably contains indium. It is also possible to use an organic EL element as the light-emitting element. For example, the first terminal of the light-emitting element functions as an anode, and the second terminal of the light-emitting element functions as a cathode. For example, the second terminal of the light-emitting element is connected to the second wiring. When the light-emitting element emits light, a higher potential is supplied to the first wiring than to the second wiring.

[0019] According to one aspect of the present invention, it is possible to provide a semiconductor device in which the effects of characteristic variations are reduced; or a semiconductor device with low power consumption; or a semiconductor device with good reliability; or a novel semiconductor device; or a display device with high display quality; or a novel display device.

[0020] Furthermore, the description of the above effects does not preclude the existence of other effects. Other effects can be naturally found from the description in the specification, drawings, claims, etc., and it is possible to extract other effects from the description in the specification, drawings, claims, etc. Furthermore, one aspect of the present invention does not need to have all of these effects (the above effects and other effects).

[0021] Figures 1A and 1B illustrate an example of the configuration of a semiconductor device. Figures 2A and 2B illustrate an example of the configuration of a semiconductor device. Figure 3 illustrates an example of the configuration of a semiconductor device. Figures 4A and 4B illustrate an example of the configuration of a multi-gate transistor. Figure 4C illustrates an example of the configuration of a semiconductor device. Figure 5A is a timing chart for illustrating an example of the operation of a semiconductor device. Figure 5B is a diagram illustrating the relationship between the threshold voltage of a transistor and the voltage applied to the back gate. Figures 6A and 6B are diagrams for illustrating an example of the operation of a semiconductor device. Figures 7A and 7B are diagrams for illustrating an example of the operation of a semiconductor device. Figure 8 is a diagram for illustrating an example of the operation of a semiconductor device. Figures 9A and 9B illustrate an example of the configuration of a semiconductor device. Figures 10A and 10B illustrate an example of the configuration of a semiconductor device. Figure 11 is a diagram for illustrating an example of the configuration of a semiconductor device. Figure 12 is a diagram for illustrating an example of the configuration of a semiconductor device. Figure 13 is a diagram for illustrating an example of the configuration of a semiconductor device. Figure 14 is a timing chart for illustrating an example of the operation of a semiconductor device. Figures 15A and 15B are diagrams for illustrating an example of the operation of a semiconductor device. Figures 16A and 16B are diagrams illustrating an example of the operation of a semiconductor device. Figure 17 is a diagram illustrating an example of the operation of a semiconductor device. Figures 18A, 18B, and 18C are diagrams illustrating the configuration of a transistor. Figures 19A, 19B, and 19C are diagrams illustrating the configuration of a transistor. Figures 20A and 20B are diagrams illustrating the configuration of a transistor. Figures 21A and 21B are diagrams illustrating the configuration of a transistor. Figures 22A, 22B, and 22C are diagrams illustrating the configuration of a transistor. Figures 23A, 23B, and 23C are diagrams illustrating the configuration of a transistor. Figure 24 is a diagram illustrating an example of a planar configuration of a semiconductor device. Figure 25 is a diagram illustrating an example of a planar configuration of a semiconductor device. Figures 26A and 26B are diagrams illustrating an example of a cross-sectional configuration of a semiconductor device. Figures 27A and 27B are diagrams illustrating an example of a cross-sectional configuration of a semiconductor device. Figures 28A and 28B are diagrams illustrating an example of a cross-sectional configuration of a semiconductor device. Figure 29A is a perspective view showing an example of the configuration of a display device.Figures 29B, 29C, 29D, 29E, and 29F are plan views showing an example of a pixel arrangement. Figures 30A, 30B, 30C, and 30D are diagrams illustrating an example of the configuration of a light-emitting element. Figures 31A, 31B, 31C, and 31D are diagrams illustrating an example of the configuration of a light-emitting element. Figures 32A, 32B, 32C, and 32D are diagrams illustrating an example of the configuration of a light-emitting element. Figures 33A, 33B, and 33C are diagrams illustrating an example of the configuration of a light-emitting element. Figures 34A and 34B are block diagrams illustrating an example of the configuration of a display device. Figure 35 is a cross-sectional view showing an example of the configuration of a display device. Figures 36A, 36B, 36C, and 36D are diagrams showing an example of an electronic device. Figures 37A, 37B, 37C, 37D, 37E, and 37F are diagrams showing an example of an electronic device. Figures 38A, 38B, 38C, 38D, 38E, 38F, and 38G show examples of electronic equipment. Figures 39A1, 39A2, 39A3, 39A4, 39A5, 39A6, 39A7, and 39B1, 39B2, 39B3, 39B4, 39B5, and 39B6 illustrate electrical connections.

[0022] 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 thereof. Accordingly, the present invention shall not be construed as being limited to the contents of the following embodiments.

[0023] In the drawings and other illustrations relating to this specification, the size, layer thickness, or area may be exaggerated for clarity. Therefore, the size or aspect ratio is not necessarily limited to those shown. Furthermore, the drawings are schematic representations of ideal examples and are not limited to the shapes or values ​​shown in the drawings.

[0024] In the configuration of the embodiment of the invention, the same reference numerals are used in common across different drawings for the same part or parts having similar functions, and repeated explanations may be omitted. Also, when referring to similar functions, the same hatching pattern may be used, and no reference numerals may be assigned. Furthermore, in order to make the drawings easier to understand, the description of some components may be omitted in perspective views or plan views, etc.

[0025] In this specification, ordinal numbers such as "first," "second," etc., 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 "first" in one embodiment of this specification may be referred to as "second" in another embodiment or in the claims. Also, a constituent element referred to as "first" in one embodiment of this specification may be omitted in another embodiment or in the claims. Furthermore, even if a term in this specification does not have an ordinal number, an ordinal number may be added in the claims to avoid confusion of constituent elements. Also, even if a term in this specification has an ordinal number, a different ordinal number may be added in the claims. Furthermore, even if a term in this specification has an ordinal number, the ordinal number may be omitted in the claims.

[0026] 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.

[0027] Furthermore, the terms "above" and "below" do not limit the positional relationship of the components to being directly above or below each other and in direct contact. For example, the expression "electrode B on insulating layer A" does not require that electrode B be formed in direct contact with insulating layer A, and does not exclude cases where other components are included between insulating layer A and electrode B.

[0028] 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.

[0029] In this specification, terms such as "film" and "layer" can be interchanged as needed. For example, the term "conductive layer" may be changed to the term "conductive film." Or, for example, the term "insulating film" may be changed to the term "insulating layer." Alternatively, depending on the circumstances, terms such as "film" and "layer" can be omitted and replaced with other terms. For example, the term "conductive layer" or "conductive film" may be changed to the term "conductor." Or, 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."

[0030] 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" or "conductive layer" depending on the context.

[0031] In this specification, terms such as "wiring," "signal line," and "power line" can be interchanged with each other as appropriate or 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. Furthermore, the term "potential" applied to wiring may be changed to the term "signal," and vice versa.

[0032] In this specification, "source" refers to a source region, a source electrode, or a source wiring. A source region refers to one of two regions of a semiconductor layer adjacent to a channel formation region. A source electrode refers to a conductive layer that includes the portion connected to the source region.

[0033] In this specification, "drain" refers to a drain region, a drain electrode, or drain wiring. A drain region refers to the other of two regions adjacent to a channel formation region within a semiconductor layer. A drain electrode refers to a conductive layer that includes the portion connected to the drain region.

[0034] In this specification, "gate" means gate electrode or gate wiring. A gate electrode is an electrode that overlaps with the semiconductor layer of a transistor and has the function of controlling the resistance between the source and drain of the transistor by the supplied voltage.

[0035] In this specification, one of the source or drain of a transistor may be referred to as the "first terminal," and the other of the source or drain of a transistor may be referred to as the "second terminal."

[0036] In this specification, "parallel" means a state in which two lines are positioned at a relative angle of -10° or more and 10° or less. Therefore, the case of -5° or more and 5° or less is also included. Furthermore, "approximately parallel" or "roughly parallel" means a state in which two lines are positioned at a relative angle of -15° or more and 15° or less. Furthermore, "perpendicular" means a state in which two lines are positioned at a relative angle of 80° or more and 100° or less. Therefore, the case of 85° or more and 95° or less is also included. Furthermore, "approximately perpendicular" or "roughly perpendicular" means a state in which two lines are positioned at a relative angle of 60° or more and 120° or less.

[0037] Furthermore, voltage often refers to the potential difference between a certain potential and a reference potential (e.g., ground potential or source potential). Therefore, voltage and potential are often interchangeable. In this specification, unless otherwise specified, voltage and potential are considered interchangeable.

[0038] Furthermore, in this specification, the high power supply potential VDD (hereinafter also simply referred to as "VDD") refers to a power supply potential that is higher than the low power supply potential VSS. The low power supply potential VSS (hereinafter also simply referred to as "VSS") refers to a power supply potential that is lower than the high power supply potential VDD. The ground potential GND (hereinafter also simply referred to as "GND") can also be used as VDD or VSS. For example, if VDD is GND, then VSS is at a lower potential than GND, and if VSS is GND, then VDD is at a higher potential than GND.

[0039] In this specification, the "on state" of a transistor means that the source and drain of the transistor are conductive (a state in which current can be conducted). The "off state" of a transistor means that the source and drain of the transistor are non-conductive (a state in which it can be considered blocked).

[0040] Furthermore, in this specification, "on-current" refers to the current that flows between the source and drain when the transistor is in the ON state. "Off-current" refers to the current that flows between the source and drain when the transistor is in the OFF state.

[0041] In this specification, potential H is the potential that turns an n-channel field-effect transistor (also called an "n-type transistor") on, and the potential that turns a p-channel field-effect transistor (also called a "p-type transistor") off. Similarly, potential L is the potential that turns an n-type transistor off, and the potential that turns a p-type transistor on. Therefore, potential H is higher than potential L. Potential H may be equal to VDD. Potential L may be equal to VSS. Furthermore, unless otherwise specified, the transistors described in this specification are enhancement-type (normally-off) transistors.

[0042] Furthermore, in drawings and other diagrams, to clearly indicate the potential of wiring and electrodes, a "H" indicating a high potential or an "L" indicating a low potential may be added adjacent to the wiring and electrodes. In addition, a "H" or "L" enclosed in a box may be added to wiring and electrodes where a potential change has occurred. In addition, if a transistor is in the off state, an "×" symbol may be added over the transistor. In addition, an arrow indicating the direction of current flow may be added.

[0043] 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 shall include an error margin of plus or minus 10%.

[0044] Furthermore, 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." Also, the X, Y, and Z directions are directions that intersect each other. For example, 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."

[0045] Generally, a "capacitor" has a configuration in which two electrodes face each other with an insulator (dielectric) in between. In this specification, the term "capacitor element" includes the case of the aforementioned "capacitor." That is, in this specification, the term "capacitor element" includes cases in which two electrodes face each other with an insulator in between, cases in which two wires face each other with an insulator in between, or cases in which two wires are arranged with an insulator in between. In this specification, one of the two electrodes may be referred to as the "first electrode" or "first terminal," and the other as the "second electrode" or "second terminal."

[0046] In this specification, when the same symbol is used for multiple elements, and especially when it is necessary to distinguish them, the symbol may be accompanied by an identifying code such as "A", "b", "_1", "[n]", or "[m,n]".

[0047] In this specification, "connection" includes, for example, "electrical connection." When "electrical connection" is used to define the connection relationship of circuit elements as a physical object, "electrical connection" includes, for example, "direct connection" and "indirect connection." "A and B are directly connected" means, for example, that A and B are connected without the use of a circuit element (e.g., a transistor or a switch; however, wiring is not a circuit element). On the other hand, "A and B are indirectly connected" means, for example, that A and B are connected via one or more circuit elements. A, B, and C (described later) refer to objects such as elements, circuits, wiring, electrodes, terminals, semiconductor layers, and conductive layers.

[0048] Here, when we define "A and B are indirectly connected," it refers to the following connection relationship, as an example: That is, assuming the circuit is operating, if there are times during the circuit's operation when electrical signals are exchanged or potential interactions occur between A and B, then such a circuit can be defined as having "A and B indirectly connected" as a physical object. Even if there are times when no electrical signals are exchanged or potential interactions occur between A and B, if there are times during the circuit's operation when electrical signals are exchanged or potential interactions occur between A and B, then it can be defined as having "A and B indirectly connected." Note that "A and B are indirectly connected" is a definition of the connection relationship between circuit elements as a physical object. Therefore, for example, even if no power supply voltage is supplied to the circuit and the circuit is not operating, the circuit can be defined as having "A and B indirectly connected" as a physical object (however, as an example, this is limited to cases where, when power supply voltage is supplied to the circuit and the circuit is operating, electrical signals are exchanged or potential interactions occur between A and B during the circuit's operation).

[0049] The following are specific examples of "indirect connections". First, an example of a case where "A and B are indirectly connected" is when A and B are connected via the source and drain of one or more transistors, as shown in Figures 39A1 and 39A2. Another example of a case where "A and B are indirectly connected" is when A and B are connected via one or more switches. When "A and B are indirectly connected", assuming the circuit is operating, one transistor between A and B will be in an ON state, conducting state, or a state in which current can flow at least once. Note that when "A and B are indirectly connected", this includes a time when one transistor between A and B is in an OFF state or non-conducting state. When "A and B are indirectly connected" and multiple transistors are connected between A and B, assuming the circuit is operating, each of the multiple transistors between A and B will be in an ON state, conducting state, or a state in which current can flow at least once. In other words, when "A and B are indirectly connected," it is not necessary for all of the transistors to be in an ON state, a conducting state, or a state in which current can flow simultaneously. Therefore, when "A and B are indirectly connected," it includes cases where the transistors between A and B are in an OFF state or a non-conducting state at the same time or at different times. As another example, as shown in Figure 39A3, when A and C are connected via the source and drain of transistor TrP, and B and C are connected via the source and drain of transistor TrQ, it can be defined as "A and C are indirectly connected," "B and C are indirectly connected," or "A and B are indirectly connected." However, as will be discussed later, if a constant potential V is supplied to C from a power supply or GND, it can be said that "A and C are indirectly connected," or "B and C are indirectly connected," but it cannot be said that "A and B are indirectly connected."

[0050] Having shown examples of cases where a connection can be considered "indirect" and cases where it cannot, let's look at another example of a case where a connection cannot be considered "indirect." Even if electrical signals are exchanged or potential interactions occur between A and B during the operation of the circuit, there are exceptional cases where it cannot be said that "A and B are indirectly connected." An example of such an exceptional case is when A and B are connected via an insulator. In other words, when A and B are connected via an insulator, it cannot be said that "A and B are indirectly connected." A specific example of when A and B are connected via an insulator is when a capacitive element is connected between A and B, as shown in Figure 39A4. Another example of when A and B are connected via an insulator is when a transistor gate insulating film is interposed between A and B, as shown in Figure 39A5. In this case, it cannot be said that "A (the gate of the transistor) and B (the source or drain of the transistor) are indirectly connected."

[0051] Another example of a situation where it cannot be said that "A and B are indirectly connected" is when there is no timing for the exchange of electrical signals or potential interaction between A and B. For example, as shown in Figures 39A6 and 39A7, multiple transistors are connected via sources and drains in the path from A to B, and a constant potential V is supplied to the nodes between the transistors from a power source or GND. In this case, it cannot be said that "A and B are indirectly connected," but it can be said that "A and V are indirectly connected," or "B and V are indirectly connected." In Figure 39A3, if A and C are connected via the source and drain of transistor TrP, and B and C are connected via the source and drain of transistor TrQ, and a constant potential V is supplied to C from a power supply or GND, then the connection relationship is the same as in Figures 39A6 and 39A7, so it cannot be said that "A and B are indirectly connected," but it can be said that "A and C are indirectly connected" or "B and C are indirectly connected."

[0052] As shown above, we have provided an example of "indirect connection." As an example, the provisions for "indirect connection" are included in the provisions for "electrical connection," so if "A and B are indirectly connected," then "A and B are electrically connected."

[0053] Next, we will show specific examples of "direct connection." Examples of cases where "A and B are directly connected" include cases where A and B are connected without a circuit element in between, as shown in Figures 39B1, 39B2, and 39B3. Furthermore, as shown in Figures 39B4 and 39B5, when A and B are connected to a power supply that provides a constant potential V, or to GND, without a circuit element in between, we can say that "A and B are directly connected," "A and V are directly connected," or "B and V are directly connected." Furthermore, as shown in Figure 39B6, even when A (or B) is connected to a constant potential V via the source and drain of a transistor, we can say that "A and B are directly connected." Furthermore, since A and V, or B and V, are connected via the source and drain of a transistor, they cannot be said to be directly connected, and we can say that "A and V are indirectly connected," or "B and V are indirectly connected."

[0054] As shown above, an example of "direct connection" has been given, but as an example, since the provisions for "direct connection" are included in the provisions for "electrical connection," if "A and B are directly connected," then "A and B are electrically connected."

[0055] Furthermore, one aspect of the present invention is all or part of the circuit configuration described herein. Therefore, one aspect of the present invention satisfies the support requirement and the clarity requirement even if it does not include all or part of the operation described herein.

[0056] (Embodiment 1) A semiconductor device 10A and a semiconductor device 10B according to one aspect of the present invention will be described with reference to the drawings. Both semiconductor device 10A and semiconductor device 10B can be used as pixel circuits for a display device.

[0057] <<Configuration Example>> Figure 1A shows an example of the circuit configuration of the semiconductor device 10A. The semiconductor device 10A has transistors TrD, Tr1, Tr2, capacitive element C1, capacitive element C2, and light-emitting element 61. Transistors TrD and Tr2 are each transistors with back gates.

[0058] One source or drain of transistor TrD is connected to wiring AN, and the other source or drain is connected to one electrode of capacitive element C1, one electrode of capacitive element C2, and one terminal (first terminal) of light-emitting element 61. The gate of transistor TrD is connected to one source or drain of transistor Tr1 and the other electrode of capacitive element C1. The back gate of transistor TrD is connected to one source or drain of transistor Tr2 and the other electrode of capacitive element C2.

[0059] The source or drain of transistor Tr1 is connected to wiring SL. The gate of transistor Tr1 is connected to wiring GL. The gate of transistor Tr2 is connected to the source or drain of transistor Tr2. Also, the gate of transistor Tr2 and the source or drain of transistor Tr2 are connected to wiring PL. The back gate of transistor Tr2 is connected to wiring AN. The other terminal (second terminal) of the light-emitting element 61 is connected to wiring CA. For example, the first terminal of the light-emitting element 61 functions as an anode, and the second terminal of the light-emitting element 61 functions as a cathode.

[0060] Furthermore, in Figure 1A, the region where the gate of transistor TrD, one of the source or drain of transistor Tr1, and the other electrode of capacitive element C1 are connected and are always at the same potential is shown as node Nd1. Also, the region where the other of the source or drain of transistor TrD, one electrode of capacitive element C1, one electrode of capacitive element C2, and one terminal of light-emitting element 61 are connected and are always at the same potential is shown as node Nd2. Also, the region where the back gate of transistor TrD, one of the source or drain of transistor Tr2, and the other electrode of capacitive element C2 are connected and are always at the same potential is shown as node Nd3.

[0061] In the semiconductor device 10A, transistor TrD functions as a drive transistor. Transistor TrD has the function of controlling the current flowing to the light-emitting element 61. Transistors Tr1 and Tr2 also function as switches.

[0062] Figure 1B shows the equivalent circuit diagram of semiconductor device 10A. In Figure 1B, transistor Tr1 is represented as switch SW1. In Figure 1B, one terminal of switch SW1 (first terminal) corresponds to either the source or the drain of transistor Tr1, and the other terminal of switch SW1 (second terminal) corresponds to the other source or drain of transistor Tr1. Also in Figure 1B, transistor Tr2 is represented by switch SW2 and diode D1 connected in parallel with switch SW2. In Figure 1B, one terminal of switch SW2 (first terminal) corresponds to either the source or the drain of transistor Tr2, and the other terminal of switch SW2 (second terminal) corresponds to the other source or drain of transistor Tr2. Furthermore, the anode of diode D1 is connected to one terminal of switch SW2, and the cathode is connected to the other terminal of switch SW2.

[0063] It is also possible to use mechanical switches as switch SW1 and switch SW2. 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 a conductive state and a non-conductive state.

[0064] Furthermore, it is also possible to use a transistor with a back gate as transistor Tr1. Figure 2A shows an example of a circuit configuration when a transistor with a back gate is used as transistor Tr1 in the semiconductor device 10A.

[0065] Here, let's explain the back gate of a transistor. The gate and back gate of a transistor are positioned so as to sandwich the channel formation region of the semiconductor layer. Both the gate and back gate are formed from a conductive layer or a semiconductor layer with low resistivity. The back gate can function in the same way as the gate. When the gate is used to control the on and off states of the transistor, the potential of the back gate can be set to the same potential as the gate.

[0066] For example, when turning on a transistor with a back gate, supplying the potential to both the gate and the back gate to turn the transistor on increases the on-current compared to supplying it to only one. As shown in the transistor Tr1 in Figure 2A, connecting the gate and back gate makes it possible to keep the gate and back gate at the same potential at all times. Alternatively, by not connecting the gate and back gate and controlling the potential of the back gate independently of the gate, the Vth of the transistor can be adjusted.

[0067] Furthermore, it is possible to supply a fixed potential such as GND to the back gate. Since the gate and back gate are formed by conductive layers, sandwiching the channel formation region of the semiconductor layer between the gate and back gate makes it difficult for the electric field generated outside the transistor to act on the channel formation region (also called the "electric field shielding effect"). Therefore, providing a back gate to a transistor stabilizes the operation of the transistor. In addition, providing a back gate to a transistor reduces the variation in characteristics between multiple transistors. Providing a back gate to a transistor can improve the reliability of the transistor. Therefore, the reliability of the semiconductor device containing the transistor can be improved. Note that the electric field shielding effect can be obtained even if one or both of the gate and back gate are electrically floating (also called the "floating state"), but the effect can be enhanced by supplying potential to the gate and back gate.

[0068] Furthermore, when light is shone on the channel formation region of a transistor, the transistor's electrical characteristics may fluctuate. Also, when light is shone on the channel formation region while a voltage is applied to the transistor, the transistor's electrical characteristics may deteriorate. In other words, the reliability of the transistor may decrease. By using light-shielding conductive materials for both the gate and back gate, the deterioration of the transistor's electrical characteristics can be suppressed, and its reliability can be improved.

[0069] In this embodiment, a p-type transistor with a back gate is used as transistor Tr2. By using a p-type transistor with a back gate as transistor Tr2 and connecting the back gate to wiring AN, the Vth of transistor Tr2 can be controlled without increasing the number of wires. The operation of the semiconductor device 10A will be described later.

[0070] Furthermore, the semiconductor device 10A according to one aspect of the present invention can use transistors of various structures. For example, transistors of various configurations such as planar type, staggered type, top gate type, bottom gate type, FIN type, vertical channel type, GAA (Gate All Around) type, and CFET (Complete FET) type can be used. In addition, MOS type transistors, junction type transistors, bipolar transistors, etc. can be used as transistors according to one aspect of the present invention.

[0071] When an n-type transistor is used as the transistor in the semiconductor device 10A, it is possible to use a transistor (also referred to as an "OS transistor" or "OSFET") that uses an oxide semiconductor in the semiconductor layer where the channel is formed. Since oxide semiconductors have a band gap of 2 eV or more, the off-current is extremely small. Specifically, the off-current value of an OS transistor per 1 μm of channel width at room temperature is 1 pA (1 × 10⁻¹⁶). −１２ A) Below, 1aA (1×10 −１８ A) Below, 1zA (1×10 −２１ A) Less than or equal to 1yA (1 × 10 −２４ A) The following is possible:

[0072] By using OS transistors in the transistors that make up the semiconductor device 10A, the charge written to each node can be retained for a long period of time. Therefore, for example, when displaying still images in a display device having the semiconductor device 10A, the deterioration of display quality can be suppressed even if the refresh rate is reduced. By reducing the refresh rate, the power consumption of the display device can be reduced. Also, for example, when displaying a still image in a display device having the semiconductor device 10A, it becomes possible to continue displaying the image even if the operation of the peripheral drive circuit is stopped. This driving method of stopping the operation of the peripheral drive circuit while displaying a still image is also called "idling stop driving". By performing idling stop driving, the power consumption of the display device can be further reduced.

[0073] In particular, it is preferable to use an OS transistor, which is an n-type transistor, for transistor Tr1. A potential corresponding to the video signal is held in node Nd1. By using an OS transistor, which is an n-type transistor, for transistor Tr1, the potential written to node Nd1 can be held for a long period of time.

[0074] Furthermore, 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. In addition, 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.

[0075] Furthermore, in order to supply the current and voltage necessary for light emission to the light-emitting element 61, a transistor with a high dielectric breakdown voltage between the source and drain is preferred as the transistor TrD. For example, an OS transistor is suitable as the transistor TrD because it has a high dielectric breakdown voltage between the source and drain. In particular, when a tandem structure light-emitting element is used as the light-emitting element 61, the voltage applied to the light-emitting element 61 becomes high. Therefore, an OS transistor is preferred as the transistor TrD.

[0076] Furthermore, as transistor Tr2, it is possible to use a transistor that uses silicon in the semiconductor layer where the channel is formed (also written as "Si transistor" or "SiFET"). Si transistors make it easier to realize p-type transistors than OS transistors. In addition, Si transistors that use crystalline silicon in the semiconductor layer have a faster operating speed than OS transistors.

[0077] Thus, each transistor constituting the semiconductor device 10A has different performance requirements. By combining transistors with different semiconductor layer compositions to construct the semiconductor device 10A, it is possible to reduce power consumption, reduce the occupied area, and improve reliability of the semiconductor device 10A. Therefore, it is possible to achieve power saving, improved display quality, and improved reliability of display devices using the semiconductor device 10A. By varying the semiconductor layer composition according to the characteristics required of the transistors, the performance of the semiconductor device can be efficiently enhanced.

[0078] Furthermore, by using a combination of transistors with different semiconductor layer compositions, it becomes easier to stack the transistors that constitute the semiconductor device 10A. Figure 2B shows a perspective view in which transistors Tr1 and TrD, which are made of OS transistors, are placed above transistor Tr2, which is made of Si transistors. Figure 2B also shows an example in which a light-emitting element 61 is placed above transistors Tr1 and TrD.

[0079] By stacking the transistors that make up the semiconductor device 10A, the occupied area of ​​the semiconductor device 10A can be further reduced. Therefore, it becomes possible to improve the resolution and detail of the display device using the semiconductor device 10A, thereby improving the display quality of the display device.

[0080] Furthermore, as shown in the semiconductor device 10B in Figure 3, a p-type transistor can be used for transistor Tr1 if necessary. When a p-type transistor is used for transistor Tr1, a potential L is supplied to the wiring GL when transistor Tr1 is turned ON, and a potential H is supplied to the wiring GL when it is turned OFF. Also, in semiconductor device 10B, a transistor with a back gate can be used for transistor Tr1.

[0081] The transistors constituting the semiconductor device 10 (semiconductor device 10A, semiconductor device 10B, semiconductor device 10C, and semiconductor device 10D) are not limited to single-gate transistors with one gate between the source and drain, but can also be double-gate transistors with two gates between the source and drain. Figure 4A shows the circuit symbol for a double-gate transistor Mx.

[0082] Transistor Mx has a configuration in which transistors M1 and M2 are connected in series. In Figure 4A, one source or drain of transistor M1 is connected to terminal S, the other source or drain of transistor M1 is connected to one source or drain of transistor M2, and the other source or drain of transistor M2 is connected to terminal D. Also in Figure 4A, the gates of transistors M1 and M2 are connected and also connected to terminal G.

[0083] The transistor Mx shown in Figure 4A has the function of switching between conduction and non-conduction between terminals S and D by changing the potential of terminal G. Therefore, the double-gate transistor Mx has transistors M1 and M2 connected in series and functions as a single transistor. That is, in Figure 4A, one of the source or drain of transistor Mx is connected to terminal S, the other source or drain is connected to terminal D, and the gate is connected to terminal G. In addition, because the double-gate transistor has transistors M1 and M2 connected in series, the dielectric strength between terminals S and D is high. Therefore, it is highly reliable.

[0084] Furthermore, the transistors constituting the semiconductor device 10 may be triple-gate transistors. Figure 4B shows the circuit symbol for a triple-gate transistor Mx.

[0085] Transistor Mx has a configuration in which transistors M1, M2, and M3 are connected in series. In Figure 4B, one source or drain of transistor M1 is connected to terminal S, the other source or drain of transistor M1 is connected to one source or drain of transistor M2, the other source or drain of transistor M2 is connected to one source or drain of transistor M3, and the other source or drain of transistor M3 is connected to terminal D. Also in Figure 4B, the gates of transistors M1, M2, and M3 are connected to each other and also connected to terminal G.

[0086] The transistor Mx shown in Figure 4B has the function of switching between conduction and non-conduction between terminals S and D by changing the potential of terminal G. Therefore, the triple-gate transistor Mx has transistors M1, M2, and M3 connected in series, and functions as a single transistor. In other words, in Figure 4B, one of the source or drain of transistor Mx is connected to terminal S, the other source or drain is connected to terminal D, and the gate is connected to terminal G. Furthermore, triple-gate transistors have a higher dielectric strength between terminals S and D than double-gate transistors. Therefore, they are even more reliable.

[0087] Furthermore, the transistors constituting the semiconductor device 10 may be configured with four or more transistors connected in series. Although transistors M1 to M3 are shown as n-type transistors in Figures 4A and 4B, similar effects can be obtained with p-type transistors.

[0088] A transistor that has multiple gates and multiple gates connected together, like transistor Mx, is sometimes called a "multi-gate transistor."

[0089] A multi-gate transistor is equivalent to a transistor with a long channel length. Therefore, multi-gate transistors have better electrical characteristics in the saturation region (also called "saturation characteristics") than single-gate transistors. Thus, it is possible to use multi-gate transistors to improve the saturation characteristics of a transistor. In addition, multi-gate transistors can have a smaller off-current compared to single-gate transistors.

[0090] Specifically, the saturation characteristics of transistor TrD can be improved by using a transistor with a long channel length or a multi-gate transistor for transistor TrD. Figure 4C shows an example of a circuit configuration of semiconductor device 10A using a multi-gate transistor for transistor TrD. By improving the saturation characteristics of transistor TrD, the reproducibility of the luminescence brightness of the light-emitting element 61 in relation to the video signal written to semiconductor device 10A is improved. Therefore, the display quality of the display device using semiconductor device 10A can be improved. It is also possible to use multi-gate transistors for one or both of transistors Tr1 and Tr2. The same effect can be obtained when applied to semiconductor device 10B.

[0091] Furthermore, for transistors functioning as switches, improving operating speed (switching speed between on and off states, signal transfer speed, etc.) is more important than improving saturation characteristics. Therefore, it is preferable that transistors functioning as switches have small gate capacitance and high mobility. For example, the operating speed (switching speed between on and off states, signal transfer speed, etc.) can be increased by shortening the channel length L of the transistors functioning as switches. Therefore, by making the channel lengths L of transistors Tr1 and Tr2 shorter than the channel length L of transistor TrD, both the operating speed of the semiconductor device 10 and the reproducibility of the luminescence brightness of the light-emitting element 61 in relation to the video signal can be improved.

[0092] As the light-emitting element 61, display elements such as EL elements (EL elements containing organic and inorganic materials, organic EL elements (OLED: Organic Light Emitting Diode), inorganic EL elements), LEDs (white LEDs, red LEDs, green LEDs, blue LEDs, etc.), microLEDs, QLEDs (Quantum-dot Light Emitting Diodes), and electron emission elements can be used.

[0093] <<Operation Example>> Next, an operation example of the semiconductor device 10A shown in Figure 1A will be explained using the drawings. Figure 5A is a timing chart for explaining the operation example of the semiconductor device 10A. Figures 6A, 6B, 7A, 7B, and 8 are circuit diagrams for explaining the operation example of the semiconductor device 10A.

[0094] The wiring AN is supplied with either a potential Van or a potential Vre. The wiring CA is supplied with a potential Vca. The potential Van is supplied to the anode side of the light-emitting element 61, and the potential Vca is supplied to the cathode side of the light-emitting element 61. Therefore, the potential Van is higher than the potential Vca. Also, the potential Vre is the same as or lower than the potential Vca.

[0095] Wiring GL is supplied with either a potential H or a potential L. Wiring SL is supplied with either a potential VsH, a potential VsL, or a video signal Vdata. The potential VsH is higher than the potential VsL. The video signal Vdata is a signal with a potential between VsL and VsH. Wiring PL is supplied with either a potential VpH or a potential VpL. The potential VpH is higher than the potential VpL.

[0096] In this embodiment, the potential Van is set to 10V, the potential Vre to 0V, the potential Vca to 0V, the potential H to 6V, the potential L to 0V, the potential VsH to 6V, the potential VsL to 0V, the potential VpH to 6V, and the potential VpL to 4V. The Vth of transistors Tr1 and TrD is set to 2V each. The Vth of transistor Tr2 is set to 0V. The potential at which current begins to flow through the light-emitting element 61 is denoted as "Vel". Vel is the potential difference between the anode and cathode of the light-emitting element 61 and corresponds to the threshold voltage of the light-emitting element 61. In this embodiment, Vel is set to 2V. Note that the above potentials are examples, and the potentials supplied to the semiconductor device according to one aspect of the present invention are not limited to the above potentials.

[0097] In this embodiment, the initial state is assumed to be that potential Van is supplied to wiring AN, potential L is supplied to wiring GL, video signal Vdata is supplied to wiring SL, potential VpH is supplied to wiring PL, and potential Vca is supplied to wiring CA. Furthermore, the video signal Vdata is held at node Nd1, and the potential of node Nd2 is assumed to be slightly higher than Vel. Furthermore, the potential of node Nd3 is assumed to be higher than potential VpL. Additionally, the light-emitting element 61 is assumed to be emitting light with a brightness corresponding to the video signal Vdata.

[0098] [Period T11] During periods T11 and T12, a reset operation is performed to obtain the Vth of transistor TrD. First, during period T11, a potential Vre is supplied to wiring AN and a potential H is supplied to wiring GL (see Figures 5A and 6A). Also, a potential VsH is supplied to wiring SL and a potential VpL is supplied to wiring PL. When wiring GL reaches a potential of H, transistor Tr1 turns on, and the potential VsH supplied to wiring SL is supplied to node Nd1 via the source and drain of transistor Tr1. In this embodiment, 6V is supplied to node Nd1.

[0099] Initially, the potential of node Nd2 is equivalent to Vel, and transistor TrD is an n-type transistor. Either the source or the drain of transistor TrD is connected to wiring AN. Therefore, potential Vre is supplied to either the source or the drain of transistor TrD. In this embodiment, since potential Vre is 0V, the voltage between the gate and source of transistor TrD becomes 6V, and transistor TrD turns on. Then, potential Vre is supplied to node Nd2 via the source and drain of transistor TrD. Therefore, the potential of node Nd2 becomes 0V. Also, the potential difference between wiring CA and node Nd2 becomes 0V, which is below Vel, so the light emission of the light-emitting element 61 stops.

[0100] Furthermore, when the potential of wiring AN becomes potential Vre (0V in this embodiment), transistor Tr2 turns on, and potential VpL is supplied to node Nd3 via the source and drain of transistor Tr2. In this embodiment, 4V is supplied to node Nd3.

[0101] The Vth of transistor TrD fluctuates in proportion to the potential difference between the back gate and source of transistor TrD (also written as "Vbgs"). Here, the relationship between Vbgs and Vth will be explained using Figure 5B. Figure 5B is a graph showing the Vbgs dependence of Vth for a transistor where Vth is positive when Vbgs is 0V. In Figure 5B, the horizontal axis represents Vbgs and the vertical axis represents Vth. As shown by the line 55, when Vbgs changes in the positive direction, Vth changes in the negative direction.

[0102] Furthermore, the gate structure and back gate structure of a transistor are often different. Therefore, a 1V change in Vbgs does not necessarily mean a 1V change in Vth. The change in Vth in relation to the change in Vbgs can be expressed by the coefficient Kbg. The coefficient Kbg corresponds to the slope of the straight line 55. Therefore, if the change in Vbgs is a and the change in Vth is b, the coefficient Kbg can be expressed as a / b.

[0103] In this embodiment, Vth is assumed to be negative when Vbgs is 4V. Therefore, it is possible to supply a potential VsL (0V) to the wiring SL during period T11. On the other hand, by supplying a potential VsH (6V) to the wiring SL during period T11, the on-current of transistor TrD can be increased. By increasing the on-current of transistor TrD, the potential of node Nd2 can be brought to potential Vre more quickly. Furthermore, it becomes possible to omit period T12, which will be described later.

[0104] [Period T12] During period T12, a potential VsL is supplied to the wiring SL (see Figures 5A and 6B). The potential VsL supplied to the wiring SL is supplied to node Nd1 via the source and drain of transistor Tr1. Therefore, the potential at node Nd1 becomes 0V. That is, 0V is applied to the gate of transistor TrD.

[0105] Furthermore, during period T12, Vbgs is 4V, and Vth of transistor TrD is negative, so transistor TrD remains in the ON state.

[0106] [Period T13] During period T13, a potential L is supplied to the wiring GL (see Figures 5A and 7A). As a result, transistor Tr1 turns off and node Nd1 becomes floating. Also, a potential Van is supplied to the wiring AN. In this embodiment, 10V is supplied to the wiring AN as the potential Van.

[0107] Since transistor TrD is an n-type transistor, node Nd2 functions as the source, and the potential difference between the gate and source (also written as "Vgs") is 0V.

[0108] On the other hand, the Vbgs of transistor TrD is 4V and Vth is negative, so transistor TrD is in the ON state. Therefore, the potential of wiring AN is supplied to node Nd2 via the source and drain of transistor TrD, and the potential of node Nd2 rises.

[0109] At this time, node Nd1, which is connected to node Nd2 via the capacitive element C1, is in a floating state, so the potential of node Nd1 rises in accordance with the potential rise of node Nd2. Therefore, Vgs remains at 0V.

[0110] Transistor Tr2 is connected to node Nd3, which is connected to node Nd2 via capacitive element C2. Since transistor Tr2 functions as an anode on the node Nd3 side, when the potential of node Nd3 rises, the charge corresponding to the rise moves to wiring PL. Therefore, even if the potential of node Nd2 rises, the potential of node Nd3 remains at potential VpL. Consequently, Vbgs decreases as the potential of node Nd2 rises. When the potential of node Nd2 rises and Vbgs reaches a potential corresponding to Vth of transistor TrD, transistor TrD turns off. Therefore, the rise in potential of node Nd2 stops.

[0111] [Period T14] During period T14, a potential VpH is supplied to the wiring PL (see Figures 5A and 7B). In this embodiment, 6V is supplied as the potential VpH. The potential VpH is set to be higher than the potential of node Nd3. By setting the potential VpH to be higher than the potential of node Nd3, a reverse bias is applied to the transistor Tr2, which functions as a diode. Therefore, the cathode potential becomes higher than the anode potential, and the potential of node Nd3 is maintained. In addition, to prevent the transistor Tr2 from turning on, the potential VpH is set to be lower than the potential Van.

[0112] Furthermore, since node Nd3 is in a floating state, if the potential of node Nd2 fluctuates, the potential of node Nd3 will fluctuate similarly. In other words, even if the potential of node Nd2 fluctuates, Vbgs can be kept constant.

[0113] Furthermore, during period T14, a potential H is supplied to wiring GL, and a video signal Vdata is supplied to wiring SL. When a potential H is supplied to wiring GL, transistor Tr1 turns on, and a video signal Vdata is supplied to node Nd1.

[0114] [Period T15] During period T15, a potential L is supplied to the wiring GL, turning off transistor Tr1 (see Figures 5A and 8). When transistor Tr1 is turned off, node Nd1 becomes floating, and the video signal Vdata is held in node Nd1.

[0115] Transistor TrD supplies a current to the light-emitting element 61 corresponding to the video signal Vdata. The light-emitting element 61 emits light with a brightness corresponding to the current. When this current flows through the light-emitting element 61, the potential of node Nd2 rises to potential Vel + α, where α is the potential difference corresponding to the current. The potential of node Nd1 also rises to video signal Vdata + potential Vel + α, and the potential of node Nd3 also rises to potential VpL + potential Vel + α. Therefore, the Vgs and Vbgs of transistor TrD remain constant even when the amount of current flowing through the light-emitting element 61 changes.

[0116] In this way, the potential corresponding to Vth of transistor TrD, which functions as a driving transistor, is obtained as Vbgs, and the brightness variation of the semiconductor device 10A used as a pixel circuit can be reduced. Therefore, the display quality of the display device using the semiconductor device 10A can be improved.

[0117] Furthermore, as explained in the above example of operation, in one aspect of the present invention, the semiconductor device 10A can use the wiring AN connected to either the source or drain of transistor TrD as wiring that supplies potential to the back gate of transistor Tr2. Therefore, the number of wirings connected to the semiconductor device 10A can be reduced.

[0118] Furthermore, the Vth that can be corrected by the semiconductor device 10A can be expressed by formula (1).

[0119]

[0120] For example, assuming a coefficient Kbg of 1.6, under the operating conditions exemplified in this embodiment, Vth can be corrected from over 1.25V to less than 2.5V.

[0121] Furthermore, by swapping the potentials L and H supplied to the wiring GL, the semiconductor device 10B can operate in the same way as the semiconductor device 10A.

[0122] The configuration shown in this embodiment can be used in appropriate combination with the configurations shown in other embodiments.

[0123] (Embodiment 2) In this embodiment, semiconductor devices 10C and 10D according to one aspect of the present invention will be described with reference to the drawings. Both semiconductor devices 10C and 10D can be used as pixel circuits for a display device. Semiconductor device 10C is a modified example of semiconductor device 10A. Semiconductor device 10D is a modified example of semiconductor device 10C and also a modified example of semiconductor device 10B. Therefore, matters not described in this embodiment can be referenced to Embodiment 1, etc.

[0124] <<Configuration Example>> Figure 9A shows an example of the circuit configuration of the semiconductor device 10C. The semiconductor device 10C shown in Figure 9A has a configuration in which transistor Tr3 is added to the semiconductor device 10A shown in Figure 1A.

[0125] One source or drain of transistor Tr3 is connected to the other source or drain of transistor TrD, one electrode of capacitive element C1, one electrode of capacitive element C2, and one terminal of light-emitting element 61. The other source or drain of transistor Tr3 is connected to wiring V1.

[0126] Furthermore, in semiconductor device 10C, the region where the other source or drain of transistor TrD, one electrode of capacitive element C1, one electrode of capacitive element C2, one terminal of light-emitting element 61, and one source or drain of transistor Tr3 are connected and are always at the same potential is indicated as node Nd2.

[0127] Transistor Tr3 functions as a switch. Figure 9B shows the equivalent circuit diagram of semiconductor device 10C. In Figure 9B, transistor Tr3 is represented as switch SW3. In Figure 9B, one terminal of switch SW3 (first terminal) corresponds to either the source or the drain of transistor Tr3, and the other terminal of switch SW1 (second terminal) corresponds to the other source or drain of transistor Tr3. Also, similar to switches SW1 and SW2, a mechanical switch can be used as switch SW3.

[0128] Furthermore, it is also possible to use transistors with back gates as transistors Tr1 and Tr3. Figure 10A shows an example of a circuit configuration when transistors with back gates are used for transistors Tr1 and Tr3 included in the semiconductor device 10C.

[0129] Furthermore, as shown in the semiconductor device 10D in Figure 10B, it is also possible to use p-type transistors for transistors Tr1 and Tr3 as needed. When p-type transistors are used for transistors Tr1 and Tr3, a potential L is supplied to the wiring GL when transistors Tr1 and Tr3 are turned ON, and a potential H is supplied to the wiring GL when they are turned OFF. In addition, in the semiconductor device 10D, transistors with back gates can also be used for transistors Tr1 and Tr3.

[0130] Furthermore, as shown in Figure 11 of the semiconductor device 10C, it is also possible to connect the gates of transistor Tr1 and transistor Tr3 to different wirings. Figure 11 shows an example configuration in which the gate of transistor Tr1 is connected to wiring GL1 and the gate of transistor Tr3 is connected to wiring GL2. In this way, transistors Tr1 and Tr3 can be controlled independently. Therefore, the degree of freedom in the operation method of the semiconductor device 10C can be increased.

[0131] Furthermore, as shown in Figure 12, by connecting the source or drain of transistor Tr3 to wiring CA, the formation of wiring V1 can be eliminated. Therefore, the occupied area of ​​semiconductor device 10C can be reduced.

[0132] Furthermore, by connecting the source or drain of transistor Tr3 to wiring AN located in an adjacent row, it is possible to eliminate the need to form wiring V1.

[0133] For example, consider the case where semiconductor devices 10C are arranged in a matrix of m rows and n columns (where m and n are integers of 2 or more) as the pixel circuit of a display device. Figure 13 shows an example of the circuit configuration of a semiconductor device 10C (semiconductor device 10C[u,v]) arranged in the u row and v column (where u is an integer from 1 to m, and v is an integer from 1 to n) and a semiconductor device 10C (semiconductor device 10C[u+1,v]) arranged in the u+1 row and v column.

[0134] In Figure 13, the wirings AN, GL, PL, and CA connected to semiconductor device 10C[u,v] are denoted as wiring AN[u], wiring GL[u], wiring PL[u], and wiring CA[u], respectively. Similarly, the wirings AN, GL, PL, and CA connected to semiconductor device 10C[u+1,v] are denoted as wiring AN[u+1], wiring GL[u+1], wiring PL[u+1], and wiring CA[u+1], respectively. Furthermore, the wiring SL connected to semiconductor device 10C[u,v] and semiconductor device 10C[u+1,v] is denoted as wiring SL[v].

[0135] In Figure 13, the source or drain of transistor Tr3 in semiconductor device 10C[u,v] is connected to wiring AN[u+1]. With this circuit configuration, during the period when potential Vre is supplied to wiring AN[u+1], the semiconductor device 10C[u,v] can acquire the potential corresponding to Vth of transistor TrD and the video signal Vdata.

[0136] By connecting the source or drain of transistor Tr3 to wiring AN located in an adjacent row, the formation of wiring V1 becomes unnecessary, and the occupied area of ​​semiconductor device 10C can be reduced.

[0137] <<Operation Example>> Next, an operation example of the semiconductor device 10C shown in Figure 9A will be explained using the drawings. Figure 14 is a timing chart for explaining the operation example of the semiconductor device 10C. Figures 15A, 15B, 16A, 16B and 17 are circuit diagrams for explaining the operation example of the semiconductor device 10C. The potential supplied to the semiconductor device 10C, the initial state, etc. are the same as in the above embodiment. The potential Vre is supplied to the wiring V1. In the configuration shown in Figure 13, the potential Van may be supplied to the source or the other drain of the transistor Tr3.

[0138] [Period T21] During periods T21 and T22, a reset operation is performed to obtain the Vth of transistor TrD. Period T21 corresponds to period T11 as shown in the above embodiment. During period T21, potential Vre is supplied to wiring AN and potential H is supplied to wiring GL (see Figures 14 and 15A). Also, potential VsH is supplied to wiring SL and potential VpL is supplied to wiring PL. When wiring GL reaches potential H, transistors Tr1 and Tr3 turn on, and the potential VsH supplied to wiring SL is supplied to node Nd1 via the source and drain of transistor Tr1. In this embodiment, 6V is supplied to node Nd1.

[0139] In semiconductor device 10C, transistors TrD and Tr3 are connected to node Nd2. Potential Vre is supplied to node Nd2 via transistor TrD and also via transistor Tr3. Semiconductor device 10C supplies potential Vre to node Nd2 through two paths. Therefore, semiconductor device 10C can shorten the time required for reset operation compared to semiconductor device 10A. Also, when potential Vre is supplied to node Nd2, the light emission of the light-emitting element 61 stops.

[0140] When the potential of wiring AN reaches potential Vre, transistor Tr2 turns on, and potential VpL is supplied to node Nd3 via the source and drain of transistor Tr2. In this embodiment, 4V is supplied to node Nd3.

[0141] [Period T22] Period T22 corresponds to period T12 as shown in the above embodiment. During period T22, a potential VsL is supplied to the wiring SL (see Figures 14 and 15B). In this embodiment, 0V is supplied to the wiring SL as the potential VsL. The potential VsL supplied to the wiring SL is supplied to node Nd1 via the source and drain of transistor Tr1. Therefore, the potential of node Nd1 becomes 0V. That is, 0V is applied to the gate of transistor TrD.

[0142] Furthermore, during period T22, Vbgs is 4V, and Vth of transistor TrD is negative, so transistor TrD remains in the ON state.

[0143] Furthermore, it is also possible to supply a potential VsL to the wiring SL during the aforementioned period T21. In the semiconductor device 10C, it is possible to supply a potential Vre to node Nd2 via the source and drain of transistor Tr3. By supplying a potential VsL to the wiring SL during period T21, it is possible to omit period T22. By omitting period T22, the time required for Vth correction can be shortened. Therefore, the operating speed of the semiconductor device 10C can be increased.

[0144] [Period T23] Period T23 corresponds to period T13 as shown in the above embodiment. During period T23, a potential L is supplied to the wiring GL (see Figures 14 and 16A). As a result, transistor Tr1 turns off and node Nd1 becomes floating. Transistor Tr3 also turns off. During period T23, a potential Van is supplied to the wiring AN. In this embodiment, 10V is supplied to the wiring AN as the potential Van.

[0145] During period T23, the Vbgs of transistor TrD is 4V. Therefore, the Vth of transistor TrD is negative, and transistor TrD is in the ON state. Thus, the potential of wiring AN is supplied to node Nd2 via the source and drain of transistor TrD. As explained in period T13, the potential of node Nd2 rises until the potential difference Vbgs between node Nd3 and node Nd2 corresponds to the potential difference of transistor TrD.

[0146] [Period T24] Period T24 corresponds to period T14 as shown in the above embodiment. During period T24, a potential VpH is supplied to the wiring PL (see Figures 14 and 16B). Similar to period T14, the potential VpH is set to a potential higher than the potential of node Nd3. By setting the potential VpH to a potential higher than the potential of node Nd3, a reverse bias is applied to the transistor Tr2, which functions as a diode. Therefore, the cathode potential becomes higher than the anode potential, and the potential of node Nd3 is maintained. In addition, to prevent the transistor Tr2 from turning on, the potential VpH is set to a potential lower than the potential Van. In this embodiment, 6V is supplied as the potential VpH.

[0147] Furthermore, when a reverse bias is applied to transistor Tr2, which functions as a diode, node Nd3 becomes floating. Therefore, the potential of node Nd3 fluctuates in accordance with the potential fluctuations of node Nd2. In other words, even if the potential of node Nd2 fluctuates, Vbgs remains constant.

[0148] Furthermore, during period T24, a potential H is supplied to wiring GL and a video signal Vdata is supplied to wiring SL. When a potential H is supplied to wiring GL, transistor Tr1 turns on and the video signal Vdata is supplied to node Nd1. If the video signal Vdata is at a potential greater than 0V, transistor TrD turns on and charge is supplied to node Nd2. In the semiconductor device 10A described above, node Nd2 is in a floating state, so the potential of node Nd2 changes. The potential of node Nd2 at this time is affected by the magnitude of the video signal Vdata, the variation in the threshold voltage Vel of the light-emitting element 61, etc. In other words, the potential difference between node Nd1 and node Nd2 may not be set accurately, and there is a risk that the light-emitting element 61 may not be able to obtain the luminescence brightness corresponding to the video signal Vdata.

[0149] In semiconductor device 10C, when the video signal Vdata is supplied to node Nd1, the potential Vre is supplied to node Nd2 via the source and drain of transistor Tr3. Since the potential of node Nd2 is fixed to the potential Vre, the potential difference between node Nd1 and node Nd2 can be set more precisely to the desired value. In other words, with the configuration of semiconductor device 10C, the potential difference between node Nd1 and node Nd2 corresponding to the video signal Vdata can be obtained more precisely than in semiconductor device 10A. Therefore, the controllability of the current flowing through the light-emitting element 61 is improved, and the display quality of the display device using semiconductor device 10C can be enhanced.

[0150] [Period T25] Period T25 corresponds to period T15 as shown in the above embodiment. During period T25, a potential L is supplied to the wiring GL, turning off transistors Tr1 and Tr3 (see Figures 14 and 17). When transistor Tr1 is turned off, node Nd1 becomes floating, and a potential corresponding to the video signal Vdata is maintained at node Nd1.

[0151] Transistor TrD supplies a current to the light-emitting element 61 corresponding to the video signal Vdata, and the light-emitting element 61 emits light with a brightness corresponding to the current. When this current flows through the light-emitting element 61, the potential of node Nd2 rises to potential Vel + α, where α is the potential difference corresponding to the current. The potential of node Nd1 also rises to video signal Vdata + potential Vel + α, and the potential of node Nd3 also rises to potential VpL + potential Vel + α. Therefore, the Vgs and Vbgs of transistor TrD remain constant even when the amount of current flowing through the light-emitting element 61 changes.

[0152] In this way, the potential corresponding to Vth of transistor TrD, which functions as a driving transistor, is obtained as Vbgs, and the brightness variation of the semiconductor device 10C used as a pixel circuit can be reduced. Therefore, the display quality of the display device using the semiconductor device 10C can be improved.

[0153] The configuration shown in this embodiment can be used in appropriate combination with the configurations shown in other embodiments.

[0154] (Embodiment 3) This embodiment describes a transistor that can be used in a semiconductor device according to one aspect of the present invention.

[0155] <Transistor Configuration Example 1> Figure 18A is a plan view of a transistor 200A that can be used in a semiconductor device according to one aspect of the present invention. Transistor 200A is an example of a planar transistor. In this specification, a planar transistor is a transistor in which the source electrode and the drain electrode are located at the same height or approximately the same height, and the current flowing through the semiconductor has a lateral component.

[0156] Figure 18B is a cross-sectional view between A1 and A2, shown by the dashed line in Figure 18A. Figure 18C is a cross-sectional view between A3 and A4, shown by the dashed line in Figure 18A. Note that some elements have been omitted in the plan view of Figure 18A for clarity. Some elements may also be omitted in other plan views.

[0157] The transistor 200A has an insulating layer 202 on a substrate 201, and a semiconductor layer 203 on the insulating layer 202. Furthermore, it has an insulating layer 204 on the insulating layer 202 and the semiconductor layer 203. It also has a conductive layer 205 on the insulating layer 204. The semiconductor layer 203 and the conductive layer 205 have overlapping regions via the insulating layer 204.

[0158] The semiconductor layer 203 has a region 203a, a channel-forming region 203b, and a region 203c. Region 203a functions as either a source region or a drain region. Region 203c functions as either a source region or a drain region. In the semiconductor layer 203, the region overlapping with the conductive layer 205 functions as the channel-forming region 203b. Therefore, the conductive layer 205 functions as the gate electrode of the transistor 200A. In addition, the insulating layer 204 functions as the gate insulating layer of the transistor 200A.

[0159] Furthermore, the length of the channel formation region 203b in the X direction is the channel length L of the transistor 200A (see Figure 18B). Also, the length of the channel formation region 203b in the Y direction is the channel width W of the transistor 200A (see Figure 18C).

[0160] Furthermore, an insulating layer 206 is provided on top of the insulating layer 204 and the conductive layer 205. In addition, an opening 207a is provided in the insulating layer 204 and the insulating layer 206 in the region overlapping with region 203a of the semiconductor layer 203. In addition, an opening 207b is provided in the insulating layer 204 and the insulating layer 206 in the region overlapping with region 203c of the semiconductor layer 203.

[0161] Furthermore, a conductive layer 208a is provided on the insulating layer 206 and the opening 207a, and a conductive layer 208b is provided on the insulating layer 206 and the opening 207b. The conductive layer 208a connects to region 203a of the semiconductor layer 203 at the bottom of the opening 207a. The conductive layer 208b connects to region 203c of the semiconductor layer 203 at the bottom of the opening 207b. Therefore, the conductive layer 208a functions as either the source electrode or the drain electrode of the transistor 200A, and the conductive layer 208b functions as either the source electrode or the drain electrode of the transistor 200A.

[0162] Furthermore, an insulating layer 209 is provided on top of the insulating layer 206 and the conductive layer 208 (conductive layer 208a and conductive layer 208b).

[0163] <Transistor Configuration Example 2> Figure 19A is a plan view of transistor 200B, which can be used in a semiconductor device according to one aspect of the present invention. Transistor 200B is a modified example of transistor 200A. To reduce repetition in the explanation, we will mainly describe the differences between transistor 200B and transistor 200A.

[0164] Figure 19B is a cross-sectional view between A1 and A2, shown by the dashed line in Figure 19A. Figure 19C is a cross-sectional view between A3 and A4, shown by the dashed line in Figure 19A.

[0165] Transistor 200B differs from transistor 200A in that it has a conductive layer 219 between the substrate 201 and the insulating layer 202. The conductive layer 219 functions as the back gate electrode of transistor 200B. Therefore, the conductive layer 219 overlaps with the channel formation region 203b. The insulating layer 202 also functions as the back gate insulating layer of transistor 200B. The thickness of the insulating layer 202 can be different or the same in the region that overlaps with the conductive layer 219 and the region that does not overlap with the conductive layer 219. Furthermore, it is preferable that the conductive layer 219 extends beyond the edge of the channel formation region 203b. That is, it is preferable to cover the channel formation region 203b with the conductive layer 219. By covering the channel formation region 203b with the conductive layer 219, the electric field shielding effect described in the above embodiment can be enhanced.

[0166] <Transistor Configuration Example 3> Figure 20A is a plan view of a transistor 200C that can be used in a semiconductor device according to one aspect of the present invention. Figure 20B is a cross-sectional view between A1 and A2 shown by the dashed line in Figure 20A.

[0167] Transistor 200C has an insulating layer 202 on a substrate 201, and a conductive layer 255 on top of the insulating layer 202. Furthermore, it has an insulating layer 257 on top of the conductive layer 255, an insulating layer 258 on top of the insulating layer 257, and an insulating layer 259 on top of the insulating layer 258. In this specification, insulating layers 257, 258, and 259 may be collectively referred to as an insulating layer 256 or a spacer layer. In addition, it has a conductive layer 261 on top of the insulating layer 259.

[0168] Furthermore, an opening 262 is provided in a region that overlaps with a part of the conductive layer 255, penetrating the conductive layer 261, the insulating layer 259, the insulating layer 258, and the insulating layer 257. A semiconductor layer 263 is also provided covering the inner wall of the opening 262.

[0169] The semiconductor layer 263 has a region that overlaps with the bottom of the opening 262 and a region that overlaps with the inner wall of the opening 262. That is, the semiconductor layer 263 has a region that is in contact with the insulating layer 256 inside the opening 262. The semiconductor layer 263 also has a region that is in contact with the conductive layer 255 and a region that is in contact with the conductive layer 261 inside the opening 262.

[0170] Furthermore, an insulating layer 264 is provided on top of the insulating layer 259, the conductive layer 261, and the semiconductor layer 263. A conductive layer 265 is also provided on top of the insulating layer 264. The conductive layer 265 has a region that overlaps with the semiconductor layer 263. The conductive layer 265 has a region that overlaps with the semiconductor layer 263 via the insulating layer 264.

[0171] Furthermore, each of the insulating layer 264 and the conductive layer 265 has a region that overlaps with the opening 262. Also, each of the insulating layer 264 and the conductive layer 265 has a region that overlaps with the inside of the opening 262. Inside the opening 262, the semiconductor layer 263 has a region that overlaps with the conductive layer 265 via the insulating layer 264, and a region that overlaps with the inner wall of the opening 262 (the side surface of the insulating layer 256).

[0172] Furthermore, an insulating layer 266 is provided on top of the insulating layer 264. It is preferable that the upper surface of the insulating layer 266 is flat. Alternatively, it is preferable that the heights (positions in the Z direction) of the upper surfaces of the insulating layer 266 and the conductive layer 265 coincide or substantially coincide. For example, the flatness of the upper surface of the insulating layer 266 can be improved by performing chemical mechanical polishing (CMP) treatment. Also, by performing CMP treatment, the positions of the upper surfaces of the insulating layer 266 and the conductive layer 265 can be made to coincide or substantially coincide. By performing CMP treatment, surface irregularities of the sample can be reduced, thereby improving the coverage of the insulating layer and conductive layer formed thereafter.

[0173] Furthermore, when an oxide semiconductor is used for the semiconductor layer 263, it is preferable that the conductive layer 255 and the conductive layer 261 in contact with the semiconductor layer 263 use a conductive material that converts the oxide semiconductor to n-type. For example, a conductive material containing nitrogen may be used. For example, a conductive material containing titanium or tantalum and nitrogen may be used. It is also possible to provide other conductive materials on top of the conductive material containing nitrogen.

[0174] Furthermore, when an oxide semiconductor is used for the semiconductor layer 263, it is preferable to use a material with reduced hydrogen and containing oxygen for the insulating layer 258. For example, a material containing silicon and oxygen may be used. Specifically, silicon oxide or silicon oxynitride may be used. Since hydrogen is an impurity element in oxide semiconductors, the contact between the oxide semiconductor semiconductor layer 263 and the hydrogen-reduced insulating layer 258 makes it less likely for the semiconductor layer 263 to become n-type. In addition, the contact between the oxide semiconductor semiconductor layer 263 and the oxygen-containing insulating layer 258 reduces oxygen vacancies in the semiconductor layer 263, stabilizing the transistor's characteristics and improving reliability.

[0175] Furthermore, when an oxide semiconductor is used for the semiconductor layer 263, the insulating layer 258 may contain excess oxygen. In this specification, excess oxygen refers to oxygen that is desorbed by heating. A material that desorbs oxygen by heating is one in which the amount of oxygen desorbed, converted to oxygen atoms, is 1.0 × 10¹⁶ by TDS (Thermal Desorption Spectroscopy) analysis.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 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. By performing the TDS analysis in the range of 100°C or higher and 700°C or lower, the amount of oxygen released in accordance with the manufacturing process of the transistor can be evaluated.

[0176] Further, when a material containing excess oxygen is used for the insulating layer 258, it is preferable to use a material through which oxygen hardly permeates for the insulating layers 257 and 259. As a material through which oxygen hardly permeates, for example, an oxide containing one or both of aluminum and hafnium, silicon nitride, or the like can be used. By using a material through which oxygen hardly permeates for the insulating layers 257 and 259, the excess oxygen contained in the insulating layer 258 is less likely to desorb to the lower layer or the upper layer. Therefore, sufficient oxygen can be supplied to the oxide semiconductor. For example, a configuration having an insulating layer (insulating layer 258) containing silicon and oxygen between two insulating layers (insulating layers 257 and 259) containing silicon and nitrogen is preferable. As the insulating layer containing silicon and nitrogen, silicon nitride or silicon oxynitride can be used. Also, as the insulating layer containing silicon and oxygen, silicon oxide or silicon oxynitride can be used.

[0177] Furthermore, when an oxide semiconductor is used for the semiconductor layer 263, by using hydrogen-containing materials for the insulating layer 257 and the insulating layer 259, hydrogen is supplied to the region of the semiconductor layer 263 in contact with the insulating layer 257 and the region of the semiconductor layer 263 in contact with the insulating layer 259, causing each region of the semiconductor layer 263 to become n-type. Therefore, the region of the semiconductor layer 263 in contact with the conductive layer 261 and the region of the semiconductor layer 263 in contact with the insulating layer 259 function as either a source region or a drain region. Also, the region of the semiconductor layer 263 in contact with the conductive layer 255 and the region of the semiconductor layer 263 in contact with the insulating layer 257 function as either a source region or a drain region.

[0178] The conductive layer 261 functions as either the source electrode or the drain electrode of the transistor 200C. The conductive layer 255 functions as the other source electrode or drain electrode of the transistor 200C. The transistor 200C is a transistor in which the source electrode and drain electrode are arranged in the Z direction. That is, the source and drain of the transistor 200C are arranged at different heights. In other words, the source and drain of the transistor 200C are arranged at different positions in the Z direction. Such a transistor is also called a "vertical channel transistor," "vertical transistor," or "VFET (Vertical Field Effect Transistor)."

[0179] In the above configuration, for the VFET transistor 200C, the length of the side surface of the insulating layer 258 viewed from the X or Y direction becomes the channel length L (channel length L1) (see Figure 20B). Therefore, the channel length L of the transistor 200C is determined according to the thickness t1 of the insulating layer 258.

[0180] Furthermore, it is preferable to use materials that do not contain hydrogen or contain very little hydrogen for the insulating layer 257 and the insulating layer 259. For example, it is preferable to use silicon nitride or silicon nitride oxide with very little hydrogen. In this case, the region of the semiconductor layer 263 in contact with the insulating layer 257 and the region of the semiconductor layer 263 in contact with the insulating layer 259 are not n-type. Therefore, the region of the semiconductor layer 263 in contact with the conductive layer 261 functions as either a source region or a drain region. Also, the region of the semiconductor layer 263 in contact with the conductive layer 255 functions as either a source region or a drain region. In addition, the region of the semiconductor layer 263 in contact with the insulating layer 258, the region of the semiconductor layer 263 in contact with the insulating layer 257, and the region of the semiconductor layer 263 in contact with the insulating layer 259 function as channel-forming regions.

[0181] In this case, the sum of the lengths of the sides of insulating layers 257, 258, and 259 as viewed from the X or Y direction becomes the channel length L (channel length L2). Therefore, the channel length L of transistor 200C is determined according to the thickness t2 obtained by adding the thicknesses of insulating layers 257, 258, and 259. Thus, transistor 200C has a channel formation region that is aligned with the side surface of insulating layer 256.

[0182] Furthermore, since the semiconductor layer 263 is provided in the opening 262, the length of the perimeter of the opening 262 when viewed from the Z direction becomes the channel width W of the transistor 200C (see Figure 20A). The length of the perimeter can be determined, for example, at a point where the thickness t1 of the insulating layer 258 is halfway, or at a point where the thickness t2 is halfway. If necessary, the length of the perimeter at any position of the opening 262 can be used as the channel width W. For example, the length of the perimeter at the bottom of the opening 262 can be used as the channel width W, or the length of the perimeter at the top of the opening 262 can be used as the channel width W. Also, although the contour (planar shape) of the opening 262 when viewed from the Z direction is shown as a circle in Figure 20A, it is not limited to this. For example, the contour of the opening 262 when viewed from the Z direction can be an ellipse, a rectangle, etc.

[0183] Furthermore, in order to improve the coverage of the semiconductor layer 263, insulating layer 264, and conductive layer 265 formed inside the opening 262, it is preferable that the inner wall of the opening 262 has a slope. Specifically, it is preferable that the sides of the insulating layer 257, insulating layer 258, and insulating layer 259 that are exposed by the formation of the opening 262 have a slope. In this specification, the angle between the bottom surface and the side surface of a layer (insulating layer, conductive layer, or semiconductor layer) is referred to as the "taper angle θ" (see Figure 20B).

[0184] By reducing the taper angle θ of insulating layers 257, 258, and 259, the coverage of the semiconductor layer 263, insulating layer 264, and conductive layer 265 formed later can be improved. In other words, the formation of the semiconductor layer 263, insulating layer 264, and conductive layer 265 on the inner wall of the opening 262 becomes easier. On the other hand, the smaller the taper angle θ, the larger the area occupied by the opening 262. Therefore, the area occupied by the transistor 200C increases, making miniaturization and high integration of the transistor 200C more difficult. Also, the larger the taper angle θ of insulating layers 257, 258, and 259, the lower the coverage of the semiconductor layer 263, insulating layer 264, and conductive layer 265, reducing the manufacturing yield and reliability of the transistor 200C. For these reasons, the taper angle θ of the sides of insulating layers 257, 258, and 259 is preferably 45° or more and less than 90°, and more preferably 50° or more and 75° or less.

[0185] Vertical transistors can reduce the area occupied by a transistor (also called a "horizontal transistor") in which the channel formation region, source region, and drain region are separately located on the XY plane. Therefore, by using vertical channel transistors in semiconductor devices, the area occupied by the semiconductor device can be reduced. Furthermore, by using vertical channel transistors in semiconductor devices, high integration of the semiconductor device can be achieved.

[0186] Furthermore, in lateral transistors, the channel length was limited by the exposure limit of photolithography. In one aspect of the present invention, the channel length can be set by the thickness of the insulating layer 256 or insulating layer 258. Therefore, the channel length of the transistor can be made into an extremely fine structure below the exposure limit of photolithography (for example, 60 nm or less, 50 nm or less, 40 nm or less, 30 nm or less, 20 nm or less, or 10 nm or less, and 1 nm or more or 5 nm or more). This increases the on-current of transistor 200C, and improves the frequency characteristics. By using a vertical channel transistor, a semiconductor device with a high operating speed can be provided.

[0187] <Transistor Configuration Example 4> Figure 21A is a plan view of transistor 200D, which can be used in a semiconductor device according to one aspect of the present invention. Transistor 200D is a modified example of transistor 200C. To reduce repetition in the explanation, we will mainly describe the differences between transistor 200D and transistor 200C.

[0188] Figure 21B is a cross-sectional view of the area between A1 and A2, shown by the dashed line in Figure 21A.

[0189] The transistor 200D has insulating layers 258a and 258b between insulating layers 257 and 259, and a conductive layer 267 between insulating layers 258a and 258b. Insulating layers 258a and 258b can be formed using the same materials and methods as insulating layer 258. Furthermore, the opening 262 of the transistor 200D is provided in a region that overlaps with a part of the conductive layer 255, penetrating the conductive layer 261, insulating layer 259, insulating layer 258b, conductive layer 267, insulating layer 258a, and insulating layer 257.

[0190] Furthermore, in transistor 200D, an insulating layer 268 is provided along the inner wall of the opening 262. Inside the opening 262, the insulating layer 268 has a region that overlaps with the side surface of the conductive layer 261, a region that overlaps with the side surface of the insulating layer 259, a region that overlaps with the side surface of the insulating layer 258b, a region that overlaps with the side surface of the conductive layer 267, a region that overlaps with the side surface of the insulating layer 258a, and a region that overlaps with the side surface of the insulating layer 257.

[0191] Furthermore, the semiconductor layer 263 in transistor 200D has, inside the opening 262, a region that overlaps with the side surface of the conductive layer 261 via the insulating layer 268, a region that overlaps with the side surface of the insulating layer 259 via the insulating layer 268, a region that overlaps with the side surface of the insulating layer 258b via the insulating layer 268, a region that overlaps with the side surface of the conductive layer 267 via the insulating layer 268, a region that overlaps with the side surface of the insulating layer 258a via the insulating layer 268, and a region that overlaps with the side surface of the insulating layer 257 via the insulating layer 268.

[0192] When conductive layer 265 is used as the gate electrode, conductive layer 267 functions as the back gate electrode. Conversely, when conductive layer 267 is used as the gate electrode, conductive layer 265 functions as the back gate electrode. Insulating layer 264 and insulating layer 268 function as either a gate insulating layer or a back gate insulating layer. Insulating layer 268 can be formed using the same materials and methods as insulating layer 264.

[0193] <Transistor Configuration Example 5> Figure 22A is a plan view of a transistor 200E that can be used in a semiconductor device according to one aspect of the present invention. Figure 22B is a cross-sectional view between A1 and A2 shown by a dashed line in Figure 22A. Figure 22C is a cross-sectional view between A3 and A4 shown by a dashed line in Figure 22A. Note that Figure 22B is a cross-sectional view of the transistor 200E in the channel length direction, and Figure 22C is a cross-sectional view of the transistor 200E in the channel width direction.

[0194] As shown in Figures 22A to 22C, the transistor 200E has a semiconductor layer 520a disposed on a substrate 201, a semiconductor layer 520b disposed on semiconductor layer 520a, conductive layers 542a and 542b disposed on semiconductor layer 520b at a distance from each other, an insulating layer 580 disposed on conductive layers 542a and 542b with an opening formed between conductive layers 542a and 542b, a conductive layer 560 disposed in the opening, an insulating layer 550 disposed between semiconductor layer 520b, conductive layer 542a, conductive layer 542b and insulating layer 580 and conductive layer 560, and a semiconductor layer 520c disposed between semiconductor layer 520b, conductive layer 542a, conductive layer 542b and insulating layer 580 and insulating layer 550. Here, as shown in Figures 22B and 22C, the upper surface of the conductive layer 560 substantially coincides with the upper end of the insulating layer 550, the upper end of the semiconductor layer 520c (the highest point when viewed from the substrate surface), and the upper surface of the insulating layer 580. In the following, semiconductor layers 520a, 520b, and 520c may be collectively referred to as semiconductor layer 520. Also, conductive layers 542a and 542b may be collectively referred to as conductive layer 542.

[0195] As shown in Figures 22A to 22C, an insulating layer 554 is positioned between the insulating layer 524, semiconductor layer 520a, semiconductor layer 520b, conductive layer 542a, conductive layer 542b, and semiconductor layer 520c, and the insulating layer 580. The insulating layer 554 is in contact with the semiconductor layer 520c, conductive layer 542a, conductive layer 542b, semiconductor layer 520a, semiconductor layer 520b, and insulating layer 524.

[0196] While the transistor 200E is shown as having a configuration in which three semiconductor layers, semiconductor layer 520a, semiconductor layer 520b, and semiconductor layer 520c, are stacked in and around the channel formation region, the present invention is not limited to this. For example, it is possible to have a configuration with a two-layer structure of semiconductor layer 520b and semiconductor layer 520c, or a stacked structure of four or more layers. It is also possible for each of the semiconductor layers 520a, semiconductor layer 520b, and semiconductor layer 520c to have a stacked structure of two or more layers.

[0197] For example, if the semiconductor layer 520c has a laminated 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 the semiconductor layer 520b and the second metal oxide has the same composition as the semiconductor layer 520a.

[0198] Here, the conductive layer 560 functions as the gate electrode of the transistor, and the conductive layers 542a and 542b function as the source electrode or drain electrode, respectively. As described above, the conductive layer 560 is formed to be embedded in the opening of the insulating layer 580 and in the region sandwiched between the conductive layers 542a and 542b. Here, the conductive layer 560, conductive layer 542a, and conductive layer 542b are arranged in a self-aligned manner with respect to the opening of the insulating layer 580. In other words, in the transistor 200E, the gate electrode can be arranged in a self-aligned manner between the source electrode and the drain electrode. Therefore, since the conductive layer 560 can be formed without providing a margin for alignment, the occupied area of ​​the transistor 200E can be reduced. This reduces the occupied area of ​​the semiconductor device. Furthermore, the integration density of the semiconductor device can be increased.

[0199] As shown in Figures 22A to 22C, the conductive layer 560 has a conductive layer 560a provided inside the insulating layer 550 and a conductive layer 560b provided so as to be embedded inside the conductive layer 560a. In the transistor 200E, the conductive layer 560 is shown as a two-layer laminated structure, but the present invention is not limited to this. For example, the conductive layer 560 may be a single-layer structure or a laminated structure of three or more layers.

[0200] The transistor 200E includes an insulating layer 202 placed on a substrate 201, an insulating layer 514 placed on the insulating layer 202, an insulating layer 516 placed on the insulating layer 514, a conductive layer 505 placed so as to be embedded in the insulating layer 516, an insulating layer 522 placed on the insulating layer 516 and the conductive layer 505, and an insulating layer 524 placed on the insulating layer 522. A semiconductor layer 520a is also placed on the insulating layer 524.

[0201] Furthermore, insulating layers 574 and 581, which function as interlayer films, are arranged on top of the transistor 200E. The insulating layer 574 is arranged in contact with the conductive layer 560, the insulating layer 550, the semiconductor layer 520c, and the insulating layer 580.

[0202] When an oxide semiconductor is used as the semiconductor layer 520, the insulating layers 522, 554, and 574 should be insulating layers that have the function of suppressing the diffusion of hydrogen (for example, at least one such as a hydrogen atom or hydrogen molecule). For example, the insulating layers 522, 554, and 574 should be insulating layers with lower hydrogen permeability than the insulating layers 524, 550, and 580. For example, silicon nitride, silicon oxide nitride, etc. can be used.

[0203] Furthermore, insulating layers 522 and 554 should be insulating layers that have the function of suppressing the diffusion of oxygen (for example, at least one such as oxygen atoms or oxygen molecules). For example, insulating layers 522 and 554 should be insulating layers with lower oxygen permeability than insulating layers 524, 550, and 580. For example, silicon nitride, silicon oxide nitride, etc., can be used.

[0204] Here, the insulating layer 524, the semiconductor layer 520, and the insulating layer 550 are sandwiched between the insulating layer 522 and the insulating layer 574. Therefore, it is possible to suppress the diffusion of impurities such as hydrogen and excess oxygen contained in the layers above the insulating layer 574 and below the insulating layer 522 into the insulating layer 524, the semiconductor layer 520, and the insulating layer 550.

[0205] Figure 22B shows an example in which a conductive layer 545 (conductive layer 545a and conductive layer 545b) is provided, which is connected to the transistor 200E and functions as a plug. It also shows an example in which an insulating layer 541 (insulating layer 541a and insulating layer 541b) is provided in contact with the side surface of the conductive layer 545 that functions as a plug. That is, the insulating layer 541 is provided in contact with the inner wall of the openings of the insulating layers 554, 580, 574, and 581. Furthermore, in Figure 22B, a first conductive layer of the conductive layer 545 is provided in contact with the side surface of the insulating layer 541, and a second conductive layer of the conductive layer 545 is provided further inside.

[0206] Here, the height of the upper surface of the conductive layer 545 and the height of the upper surface of the insulating layer 581 can be made to be approximately the same. Although the transistor 200E shows a configuration in which the first conductive layer and the second conductive layer of the conductive layer 545 are stacked, the present invention is not limited to this. For example, it is also possible to provide the conductive layer 545 as a single layer or a stacked structure of three or more layers. When a structure has a stacked structure, an ordinal number may be assigned to distinguish it according to the order of formation.

[0207] Furthermore, the thickness of the semiconductor layer 520b in the region that does not overlap with the conductive layer 542 may be thinner than the thickness of the region that overlaps with the conductive layer 542. This is formed by removing a portion of the upper surface of the semiconductor layer 520b when forming the conductive layers 542a and 542b. When a conductive film that will become the conductive layer 542 is deposited on the upper surface of the semiconductor layer 520b, a region with low resistance may be formed near the interface with the conductive film. In this way, by removing the region with low resistance of the semiconductor layer 520b located between the conductive layer 542a and the conductive layer 542b in a plan view, it is possible to prevent the formation of a channel in that region.

[0208] Next, a detailed configuration of the transistor 200E, which can be used in a semiconductor device according to one embodiment of the present invention, will be described.

[0209] The conductive layer 505 is arranged so as to have an overlapping region with the conductive layer 560 via the semiconductor layer 520. Furthermore, by embedding the conductive layer 505 in the insulating layer 516, the unevenness of the upper surfaces of the conductive layer 505 and the insulating layer 516 is reduced, thereby improving the coverage of the layers formed in subsequent processes.

[0210] The conductive layer 505 comprises conductive layer 505a, conductive layer 505b, and conductive layer 505c. Conductive layer 505a is provided in contact with the bottom surface and side wall of an opening provided in the insulating layer 516. Conductive layer 505b is provided so as to be embedded in a recess formed in conductive layer 505a. Here, the upper surface of conductive layer 505b is lower than the upper end of conductive layer 505a and the upper surface of insulating layer 516. Conductive layer 505c is provided overlapping conductive layer 505b on the inside of the opening. Conductive layer 505c is provided in contact with the upper surface of conductive layer 505b and conductive layer 505a. Here, the height of the upper surface of conductive layer 505c is equal to or approximately equal to the height of the upper end of conductive layer 505a and the upper end of insulating layer 516. In other words, conductive layer 505b is enclosed by conductive layer 505a and conductive layer 505c.

[0211] When an oxide semiconductor is used as the semiconductor layer 520, the conductive layer 505a and conductive layer 505c contain hydrogen atoms, hydrogen molecules, water molecules, nitrogen atoms, nitrogen molecules, and nitrogen oxide molecules (N ２ O, NO, NO ２ A conductive material is used that has the function of suppressing the diffusion of impurities such as copper atoms. Alternatively, a conductive material is used that has the function of suppressing the diffusion of oxygen (for example, at least one such as an oxygen atom or oxygen molecule).

[0212] By using conductive materials that have the function of reducing hydrogen diffusion in conductive layers 505a and 505c, it is possible to suppress the diffusion of impurities such as hydrogen contained in conductive layer 505b into the semiconductor layer 520 via the insulating layer 524, etc. Furthermore, by using conductive materials that have the function of suppressing oxygen diffusion in conductive layers 505a and 505c, it is possible to suppress the oxidation of conductive layer 505b and the resulting decrease in conductivity. Examples of conductive materials that have the function of suppressing oxygen diffusion include titanium, titanium nitride, tantalum, tantalum nitride, ruthenium, ruthenium oxide, etc. Therefore, conductive layer 505a can be made of the above conductive material in a single layer or a laminate. For example, titanium nitride can be used as conductive layer 505a.

[0213] Furthermore, the conductive layer 505b may be made of a conductive material mainly composed of tungsten, copper, or aluminum. For example, tungsten may be used for the conductive layer 505b. When the conductive layer 560 is used as the gate electrode, the conductive layer 505 functions as a back gate electrode.

[0214] The conductive layer 505 should be larger than the channel formation region in the semiconductor layer 520. In particular, as shown in Figure 22C, the conductive layer 505 should extend to a region outside the edge of the semiconductor layer 520 that intersects with the channel width direction. That is, the conductive layer 505 and the conductive layer 560 should be superimposed on the outside of the side surface in the channel width direction of the semiconductor layer 520, with an insulating layer in between.

[0215] With the above configuration, the channel formation region of the semiconductor layer 520 can be surrounded by the electric field of the conductive layer 560, which functions as a gate electrode, and the electric field of the conductive layer 505, which functions as a back gate electrode.

[0216] The conductive layer 505 can be extended beyond the edge of the semiconductor layer 520 and used as wiring. However, it is not limited to this configuration, and it is also possible to provide a conductive layer that functions as wiring beneath the conductive layer 505.

[0217] As the insulating layer 514, it is preferable to use an insulating material that functions as a barrier insulating film to suppress the diffusion of impurities such as water or hydrogen from the substrate side to the transistor 200E. Therefore, as the insulating layer 514, hydrogen atoms, hydrogen molecules, water molecules, nitrogen atoms, nitrogen molecules, nitrogen oxide molecules (N) ２ O, NO, NO ２ It is preferable to use an insulating material that has the function of suppressing the diffusion of impurities such as copper atoms (i.e., the above impurities are less permeable). Alternatively, it is preferable to use an insulating material that has the function of suppressing the diffusion of oxygen (i.e., at least one of oxygen atoms, oxygen molecules, etc.) (i.e., the above oxygen is less permeable).

[0218] For example, aluminum oxide or silicon nitride can be used as the insulating layer 514. This suppresses the diffusion of impurities such as water or hydrogen from the substrate side to the transistor 200E side beyond the insulating layer 514. Alternatively, it suppresses the diffusion of oxygen contained in the insulating layer 524, etc., to the substrate side beyond the insulating layer 514.

[0219] For the insulating layers 516, 580, and 581 that function as interlayer films, it is preferable to use insulating materials with a lower dielectric constant than insulating layer 514. By using materials with a low dielectric constant as interlayer films, parasitic capacitance between wiring can be reduced. For example, silicon oxide, silicon oxynitride, silicon nitride, silicon nitride, silicon oxide with added fluorine, silicon oxide with added carbon, silicon oxide with added carbon and nitrogen, or porous silicon oxide may be used as insulating layers 516, 580, and 581.

[0220] When the conductive layer 505 is used as the gate electrode, the insulating layer 522 and the insulating layer 524 function as gate insulating layers.

[0221] Here, the insulating layer 524 in contact with the semiconductor layer 520 may contain excess oxygen. For example, the insulating layer 524 may be made of silicon oxide or silicon oxynitride, etc., as appropriate. By providing an oxygen-containing insulating layer in contact with the semiconductor layer 520, oxygen deficiencies in the semiconductor layer 520 are reduced, and the reliability of the transistor 200E is improved.

[0222] As shown in Figure 22C, the thickness of the insulating layer 524 in the region that does not overlap with the insulating layer 554 and the semiconductor layer 520b may be thinner than the thickness of the other regions. In the insulating layer 524, it is preferable that the thickness of the region that does not overlap with the insulating layer 554 and the semiconductor layer 520b be such that the above-mentioned oxygen can diffuse sufficiently.

[0223] As the insulating layer 522, a material that functions as a barrier insulating film to suppress the diffusion of impurities such as water or hydrogen from the substrate side to the transistor 200E is used, similar to the insulating layer 514. For example, a material with lower hydrogen permeability than insulating layer 524 is used for insulating layer 522. By surrounding insulating layer 524, semiconductor layer 520, and insulating layer 550 with insulating layer 522, insulating layer 554, and insulating layer 574, the diffusion of impurities such as water or hydrogen from the outside to the transistor 200E can be suppressed.

[0224] Furthermore, it is preferable to use a material for the insulating layer 522 that has the function of suppressing the diffusion of oxygen (for example, at least one such as oxygen atoms or oxygen molecules) (i.e., the oxygen does not easily permeate it). For example, a material with lower oxygen permeability than the insulating layer 524 can be used for the insulating layer 522. By having the function of suppressing the diffusion of oxygen and impurities in the insulating layer 522, the amount of oxygen that diffuses from the semiconductor layer 520 to the substrate can be reduced. In addition, it is possible to suppress the reaction of the conductive layer 505 with the oxygen present in the insulating layer 524 or the semiconductor layer 520.

[0225] As the insulating layer 522, it is preferable to use an insulating layer containing an oxide of one or both of the insulating materials aluminum and hafnium. As the insulating layer containing an oxide of one or both of aluminum and hafnium, it is preferable to use aluminum oxide, hafnium oxide, or an oxide containing aluminum and hafnium (hafnium aluminate). When the insulating layer 522 is formed using such a material, the insulating layer 522 functions as a layer that suppresses the release of oxygen from the semiconductor layer 520 and the diffusion of impurities such as hydrogen from the periphery of the transistor 200E to the semiconductor layer 520.

[0226] Alternatively, the insulating layer 522 can be made by adding, for example, aluminum oxide, bismuth oxide, germanium oxide, niobium oxide, silicon oxide, titanium oxide, tungsten oxide, yttrium oxide, or zirconium oxide. Alternatively, the insulating layer 522 can be subjected to nitriding treatment. Alternatively, silicon oxide, silicon oxide nitride, or silicon nitride can be laminated onto the insulating layer 522. For example, the insulating layer 522 can be made of a structure in which silicon nitride, silicon oxide, and aluminum oxide are laminated in this order in three layers.

[0227] The insulating layer 522 is made of, for example, aluminum oxide, hafnium oxide, tantalum oxide, zirconium oxide, lead zirconate titanate (PZT), strontium titanate (SrTiO). ３ ) or (Ba, Sr)TiO ３ It is possible to use insulating layers containing so-called high-k materials such as (BST) in single-layer or multi-layer configurations. As transistors become smaller and more integrated, thinning of the gate insulating layer can lead to problems such as leakage current. By using a high-k material in the insulating layer that functions as the gate insulating layer, it is possible to reduce the gate potential during transistor operation while maintaining the physical film thickness.

[0228] Furthermore, it is possible to make the insulating layer 522 and the insulating layer 524 each 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 can be made of different materials.

[0229] The semiconductor layer 520 includes a semiconductor layer 520a, a semiconductor layer 520b on semiconductor layer 520a, and a semiconductor layer 520c on semiconductor layer 520b. By having semiconductor layer 520a below semiconductor layer 520b, the diffusion of impurities from structures formed below semiconductor layer 520a to semiconductor layer 520b can be suppressed. Furthermore, by having semiconductor layer 520c on semiconductor layer 520b, the diffusion of impurities from structures formed above semiconductor layer 520c to semiconductor layer 520b can be suppressed.

[0230] Furthermore, when an oxide semiconductor is used as the semiconductor layer 520, it is preferable that the semiconductor layer 520 has a stacked structure of multiple oxide layers with different atomic ratios of each metal atom. For example, if the semiconductor layer 520 contains at least indium (In) and element M, the ratio of the number of atoms of element M contained in semiconductor layer 520a to the total number of atoms of all elements constituting semiconductor layer 520a is made higher than the ratio of the number of atoms of element M contained in semiconductor layer 520b to the total number of atoms of all elements constituting semiconductor layer 520b. Also, the atomic ratio of element M contained in semiconductor layer 520a to In is made greater than the atomic ratio of element M contained in semiconductor layer 520b to In. Here, the semiconductor layer 520c can be the same metal oxide used in semiconductor layer 520a or semiconductor layer 520b.

[0231] The energy at the lower end of the conduction band of semiconductor layer 520a and semiconductor layer 520c should be higher than the energy at the lower end of the conduction band of semiconductor layer 520b. In other words, the electron affinity of semiconductor layer 520a and semiconductor layer 520c should be smaller than the electron affinity of semiconductor layer 520b. In this case, a metal oxide that can be used for semiconductor layer 520a can be used as semiconductor layer 520c. Specifically, it is preferable that the ratio of the number of atoms of element M contained in semiconductor layer 520c to the total number of atoms of all elements constituting semiconductor layer 520c is higher than the ratio of the number of atoms of element M contained in semiconductor layer 520b to the total number of atoms of all elements constituting semiconductor layer 520b. Furthermore, it is preferable that the atomic ratio of element M contained in semiconductor layer 520c to In is greater than the atomic ratio of element M contained in semiconductor layer 520b to In.

[0232] Here, at the junctions of semiconductor layers 520a, 520b, and 520c, the energy level at the lower end of the conduction band changes smoothly. In other words, the energy level at the lower end of the conduction band at the junctions of semiconductor layers 520a, 520b, and 520c can be said to change continuously or be continuously joined. To achieve this, it is preferable that the defect level density of the mixed layer formed at the interface between semiconductor layer 520a and semiconductor layer 520b and at the interface between semiconductor layer 520b and semiconductor layer 520c is low.

[0233] Specifically, by having semiconductor layer 520a and semiconductor layer 520b, and semiconductor layer 520b and semiconductor layer 520c, 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 semiconductor layer 520b is In-Ga-Zn oxide, then In-Ga-Zn oxide, Ga-Zn oxide, gallium oxide, etc., can be used as semiconductor layer 520a and semiconductor layer 520c. It is also possible to form a laminated structure for each of semiconductor layer 520a and semiconductor layer 520c. For example, a laminated structure of In-Ga-Zn oxide and Ga-Zn oxide on the In-Ga-Zn oxide, or a laminated structure of In-Ga-Zn oxide and gallium oxide on the In-Ga-Zn oxide can be used. In other words, a laminated structure of In-Ga-Zn oxide and an oxide that does not contain In can be used as one or both of semiconductor layer 520a and semiconductor layer 520c.

[0234] Specifically, for the semiconductor layer 520a, a metal oxide with an In:Ga:Zn ratio of 1:3:4 [atomic ratio] or close to it, or 1:1:0.5 [atomic ratio] or close to it may be used. Also, for the semiconductor layer 520b, a metal oxide with an In:Ga:Zn ratio of 4:2:3 [atomic ratio] or close to it, or 3:1:2 [atomic ratio] or close to it, or 1:1:1 [atomic ratio] or close to it may be used. Also, for the semiconductor layer 520c, a metal oxide with an In:Ga:Zn ratio of 1:3:4 [atomic ratio] or close to it, In:Ga:Zn = 4:2:3 [atomic ratio] or close to it, Ga:Zn = 2:1 [atomic ratio] or close to it, or Ga:Zn = 2:5 [atomic ratio] or close to it may be used. Furthermore, specific examples of a laminated structure for the semiconductor layer 520c include a laminated structure of In:Ga:Zn = 4:2:3 [atomic ratio] or nearby and Ga:Zn = 2:1 [atomic ratio] or nearby, a laminated structure of In:Ga:Zn = 4:2:3 [atomic ratio] or nearby and Ga:Zn = 2:5 [atomic ratio] or nearby, and a laminated structure of In:Ga:Zn = 4:2:3 [atomic ratio] or nearby and gallium oxide.

[0235] In this case, the main carrier path is the semiconductor layer 520b. By configuring semiconductor layers 520a and 520c as described above, the defect level density at the interface between semiconductor layer 520a and semiconductor layer 520b and the interface between semiconductor layer 520b and semiconductor layer 520c can be reduced. As a result, the influence of interface scattering on carrier conduction is reduced, and the transistor 200E can obtain high on-current and high frequency characteristics. Furthermore, if semiconductor layer 520c is a stacked structure, in addition to the effect of reducing the defect level density at the interface between semiconductor layer 520b and semiconductor layer 520c as described above, it is expected that the diffusion of constituent elements of semiconductor layer 520c towards the insulating layer 550 will be suppressed. More specifically, by making semiconductor layer 520c a stacked structure and positioning an oxide that does not contain In on top of the stacked structure, it is possible to suppress In that could diffuse towards the insulating layer 550. Since the insulating layer 550 functions as a gate insulating layer, if In diffuses, it will result in poor transistor characteristics. Therefore, by making the semiconductor layer 520c a stacked structure, it becomes possible to provide a highly reliable semiconductor device.

[0236] A conductive layer 542 (conductive layer 542a and conductive layer 542b) is provided on the semiconductor layer 520b, which functions as a source electrode and a drain electrode. When an oxide semiconductor is used as the semiconductor layer 520b, it is preferable to use a conductive material that is resistant to oxidation or a conductive material that maintains its conductivity even when absorbing oxygen as the conductive layer 542.

[0237] The region of the semiconductor layer 520 that is in contact with the conductive layer 542 functions as the source region or drain region of the transistor 200E. Here, the region between the conductive layer 542a and the conductive layer 542b is formed superimposed on the opening of the insulating layer 580. This allows the conductive layer 560 to be self-aligned between the conductive layer 542a and the conductive layer 542b.

[0238] The insulating layer 550 functions as a gate insulating layer. The insulating layer 550 is placed in contact with the upper surface of the semiconductor layer 520c. The insulating layer 550 can be made of 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, or silicon oxide with vacancies. For example, silicon oxide or silicon oxide nitride can be used as the insulating layer 550.

[0239] As for the insulating layer 550, an insulating material is used in which the concentration of impurities such as water or hydrogen in the insulating layer 550 is reduced, similar to the insulating layer 524. The thickness of the insulating layer 550 is 1 nm or more and 20 nm or less.

[0240] It is preferable to provide a metal oxide between the insulating layer 550 and the conductive layer 560. The metal oxide suppresses oxygen diffusion from the insulating layer 550 to the conductive layer 560. This suppresses oxidation of the conductive layer 560 by oxygen contained in the insulating layer 550.

[0241] Although the conductive layer 560 is shown as a two-layer structure in Figures 22A to 22C, a single-layer structure or a laminated structure of three or more layers can also be used.

[0242] The conductive layer 560a consists of the above-mentioned hydrogen atoms, hydrogen molecules, water molecules, nitrogen atoms, nitrogen molecules, and nitrogen oxide molecules (N ２ O, NO, NO ２ It is preferable to use a conductive material that has the function of suppressing the diffusion of impurities such as 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 an oxygen atom or oxygen molecule).

[0243] The conductive layer 560a has the function of suppressing oxygen diffusion, thereby preventing the conductive layer 560b from being oxidized by oxygen contained in the insulating layer 550 and reducing its conductivity. Examples of conductive materials that have the function of suppressing oxygen diffusion include tantalum, tantalum nitride, ruthenium, or ruthenium oxide.

[0244] The conductive layer 560b can be made of a conductive material mainly composed of, for example, tungsten, copper, or aluminum. Furthermore, since the conductive layer 560 also functions as wiring, it is preferable to use a conductive layer with high conductivity. The conductive layer 560b can also be made into a laminated structure; for example, it can be made into a laminated structure of titanium or titanium nitride and the above-mentioned conductive material.

[0245] As shown in Figures 22B and 22C, in the region of the semiconductor layer 520b that does not overlap with the conductive layer 542, in other words, in the channel formation region of the semiconductor layer 520, the side surface of the semiconductor layer 520 is covered by the conductive layer 560. This makes it easier to apply the electric field of the conductive layer 560, which functions as the gate electrode of the transistor 200E, to the side surface of the semiconductor layer 520. Therefore, the on-current of the transistor 200E can be increased and the frequency characteristics can be improved.

[0246] The insulating layer 554, like the insulating layer 514, uses an insulating material that suppresses the diffusion of impurities such as water or hydrogen from the insulating layer 580 to the transistor 200E. For example, the insulating layer 554 uses an insulating material with lower hydrogen permeability than the insulating layer 524. Furthermore, as shown in Figures 22B and 22C, the insulating layer 554 is provided in contact with the semiconductor layer 520c, conductive layer 542a, conductive layer 542b, semiconductor layer 520a, semiconductor layer 520b, and insulating layer 524. With this configuration, it is possible to suppress the diffusion of hydrogen contained in the insulating layer 580 from the upper or side surface of the conductive layer 542a, conductive layer 542b, semiconductor layer 520a, semiconductor layer 520b, and insulating layer 524 to the semiconductor layer 520.

[0247] Furthermore, the insulating layer 554 is made of an insulating material that has the function of suppressing the diffusion of oxygen (for example, at least one such as an oxygen atom or oxygen molecule) (i.e., the above-mentioned oxygen does not easily permeate it). For example, the insulating layer 554 is made of an insulating material that has lower oxygen permeability than the insulating layer 580 or the insulating layer 524.

[0248] When an oxide semiconductor is used as the semiconductor layer 520, the insulating layer 554 can be deposited using a sputtering method. By depositing the insulating layer 554 using a sputtering method in an oxygen-containing atmosphere, oxygen can be added to the vicinity of the region of the insulating layer 524 that is in contact with the insulating layer 554. This allows oxygen to be supplied from that region into the semiconductor layer 520 via the insulating layer 524. Here, the insulating layer 554 has a function to suppress upward diffusion of oxygen, thereby preventing oxygen from diffusing from the semiconductor layer 520 to the insulating layer 580. In addition, the insulating layer 522 has a function to suppress downward diffusion of oxygen, thereby preventing oxygen from diffusing from the semiconductor layer 520 to the substrate side. In this way, oxygen is supplied to the channel formation region of the semiconductor layer 520. This reduces oxygen vacancies in the semiconductor layer 520 and suppresses normally-on formation of the transistor.

[0249] As the insulating layer 554, for example, an insulating layer containing an oxide of one or both of aluminum and hafnium is formed. As the insulating layer containing an oxide of one or both of aluminum and hafnium, aluminum oxide, hafnium oxide, an oxide containing aluminum and hafnium (hafnium aluminate), etc., can be used.

[0250] The insulating layer 580 is provided on the insulating layer 524, the semiconductor layer 520, and the conductive layer 542 via the insulating layer 554. For example, as the insulating layer 580, silicon oxide, silicon oxynitride, silicon nitride, silicon oxide with added fluorine, silicon oxide with added carbon, silicon oxide with added carbon and nitrogen, or porous silicon oxide can be used. Silicon oxide and silicon oxynitride are particularly suitable because they are thermally stable. Materials such as silicon oxide, silicon oxynitride, and porous silicon oxide are particularly suitable because they can easily form regions containing oxygen that is desorbed by heating.

[0251] As the insulating layer 574, an insulating material is used that functions as a barrier insulating film to suppress the diffusion of impurities such as water or hydrogen from above into the insulating layer 580, similar to the insulating layer 514. As the insulating layer 574, for example, an insulating material that can be used for the insulating layer 514, insulating layer 554, etc., is used.

[0252] Figures 22A to 22C show an example in which an insulating layer 581, which functions as an interlayer film, is provided on top of the insulating layer 574. As the insulating layer 581, an insulating material is used in which the concentration of impurities such as water or hydrogen in the film is reduced, similar to the insulating layer 524.

[0253] The conductive layers 545a and 545b are placed in the openings formed in the insulating layers 581, 574, 580, and 554. The conductive layers 545a and 545b are provided so as to sandwich the conductive layer 560. Preferably, the upper surfaces of the conductive layers 545a and 545b are on the same plane as the upper surface of the insulating layer 581.

[0254] Furthermore, insulating layer 541a is provided in contact with the inner wall of the opening of insulating layer 581, insulating layer 574, insulating layer 580, and insulating layer 554, and a first conductive layer of conductive layer 545a is formed in contact with its side surface. Conductive layer 542a is located in at least a portion of the bottom of the opening, and conductive layer 545a is in contact with conductive layer 542a. Similarly, insulating layer 541b is provided in contact with the inner wall of the opening of insulating layer 581, insulating layer 574, insulating layer 580, and insulating layer 554, and a first conductive layer of conductive layer 545b is formed in contact with its side surface. Conductive layer 542b is located in at least a portion of the bottom of the opening, and conductive layer 545b is in contact with conductive layer 542b.

[0255] The conductive layers 545a and 545b may be conductive materials mainly composed of tungsten, copper, or aluminum. Furthermore, each of the conductive layers 545a and 545b can be constructed in a laminated structure of two or more layers.

[0256] When the conductive layer 545 has a laminated structure, it is preferable to use a conductive material that has the function of suppressing the diffusion of impurities such as water or hydrogen in the conductive layers that are in contact with the semiconductor layer 520a, semiconductor layer 520b, conductive layer 542, insulating layer 554, insulating layer 580, insulating layer 574, and insulating layer 581. For example, tantalum, tantalum nitride, titanium, titanium nitride, ruthenium, or ruthenium oxide can be used. By using such a conductive material, it is possible to suppress the absorption of oxygen contained in the insulating layer 580 into the conductive layer 545a and conductive layer 545b. In addition, it is possible to suppress the diffusion of impurities such as water or hydrogen from the layers above the insulating layer 581 through the conductive layer 545a and conductive layer 545b into the semiconductor layer 520.

[0257] For insulating layers 541a and 541b, for example, insulating layers that can be used for insulating layer 554 may be used. Since insulating layers 541a and 541b are provided in contact with insulating layer 554, it is possible to suppress the diffusion of impurities such as water or hydrogen from insulating layer 580, etc., into semiconductor layer 520 through conductive layer 545a and conductive layer 545b. Furthermore, it is possible to suppress the absorption of oxygen contained in insulating layer 580 into conductive layer 545a and conductive layer 545b.

[0258] <Transistor Configuration Example 6> A modified version of transistor 200E shown in Figure 22 is shown in Figure 23. Figure 23A is a plan view of transistor 200F, which is a modified version of transistor 200E. Figure 23B is a cross-sectional view between A1 and A2, shown by the dashed line in Figure 23A. Figure 23C is a cross-sectional view between A3 and A4, shown by the dashed line in Figure 23A. Since transistor 200F is a modified version of transistor 200E, we will mainly explain the differences between transistor 200F and transistor 200E.

[0259] Transistor 200F has a configuration that is the same as transistor 200E but without the semiconductor layer 520c and the conductive layer 505c. Reducing the number of transistor components can lower production costs. In addition, reducing the number of transistor components shortens the manufacturing process and improves the manufacturing yield.

[0260] Furthermore, the transistor 200F has a region on the outside of the semiconductor layer 520 where the insulating layer 554 and the insulating layer 522 are in contact, and the side surface of the insulating layer 524 is covered by the insulating layer 554. When an oxide semiconductor is used as the semiconductor layer 520, covering the side surface of the insulating layer 524 with the insulating layer 554 not only prevents oxygen in the semiconductor layer 520 from diffusing to the outside through the insulating layer 524, but also prevents excessive oxygen supply from the insulating layer 580 to the semiconductor layer 520.

[0261] It is preferable to provide an insulating layer between the insulating layer 580, insulating layer 524, conductive layer 542, semiconductor layer 520b, and insulating layer 550. Aluminum oxide and hafnium oxide are suitable candidates for this insulating layer. Providing this insulating layer helps to suppress oxygen desorption from the semiconductor layer 520 to the insulating layer 550, excessive oxygen supply from the insulating layer 550 to the semiconductor layer 520, and oxidation of the conductive layer 542.

[0262] <Constituent Materials of Transistors> Next, we will describe the constituent materials that can be used in transistor 200 (transistor 200A, transistor 200B, transistor 200C, transistor 200D, transistor 200E, transistor 200F).

[0263] [Substrate] When a transistor is mounted on a substrate, there are no major restrictions on the material used for the substrate. The material used for the substrate is determined according to the purpose, taking into consideration factors such as the presence or absence of light transmission and heat resistance sufficient to withstand heat treatment. For example, an insulating substrate, a semiconductor substrate, or a conductive substrate can be used. As insulating substrates, for example, glass substrates such as barium borosilicate glass and aluminoborosilicate glass, ceramic substrates, quartz substrates, sapphire substrates, and stabilized zirconia substrates (such as yttria-stabilized zirconia substrates) can be used. In addition, semiconductor substrates, flexible substrates, and resin substrates can also be used as substrates.

[0264] Examples of semiconductor substrates include silicon substrates, germanium substrates, and compound semiconductor substrates made from materials such as silicon carbide, silicon germanium, gallium arsenide, indium phosphide, zinc oxide, or gallium oxide. Furthermore, there are semiconductor substrates having insulating regions within the aforementioned semiconductor substrates, such as SOI (Silicon On Insulator) substrates. In addition, the semiconductor substrate may be a single-crystal semiconductor or a polycrystalline semiconductor.

[0265] Examples of conductive substrates include graphite substrates, metal substrates, alloy substrates, and conductive resin substrates. Alternatively, there are substrates containing metal nitrides and substrates containing metal oxides. Furthermore, there are substrates in which a conductive layer or semiconductor layer is provided on an insulating substrate, substrates in which a conductive layer or insulating layer is provided on a semiconductor substrate, and substrates in which a semiconductor layer or insulating layer is provided on a conductive substrate.

[0266] Examples of materials that can be used for flexible substrates or resin substrates include polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyacrylonitrile, acrylic resin, polyimide, polymethyl methacrylate, polycarbonate (PC), polyethersulfone (PES), polyamide (nylon, aramid, etc.), polysiloxane, cycloolefin resin, polystyrene, polyamide-imide, polyurethane, polyvinyl chloride, polyvinylidene chloride, polypropylene, polytetrafluoroethylene (PTFE), ABS resin, and cellulose nanofiber.

[0267] By using the above-mentioned material as a substrate, a lightweight semiconductor device can be provided. Furthermore, by using the above-mentioned material as a substrate, a semiconductor device that is resistant to impact can be provided. Furthermore, by using the above-mentioned material as a substrate, a semiconductor device that is less prone to damage can be provided. It is also possible to use these substrates on which elements are mounted. Elements mounted on the substrate include capacitive elements, resistive elements, switch elements, light-emitting elements, and memory elements.

[0268] [Insulating Layers] Insulating layers (insulating layers 202, 204, 206, 209, 258a, 258b, 259, 264, 266, 268, 516, 522, 524, 541, 554, 580, 574, 581, etc.) are each made of inorganic insulating films. Examples of inorganic insulating films include oxide insulating films, nitride insulating films, oxidized nitride insulating films, and nitrided oxide insulating films. Examples of oxide insulating films include silicon oxide films, aluminum oxide films, magnesium oxide films, gallium oxide films, germanium oxide films, yttrium oxide films, zirconium oxide films, lanthanum oxide films, neodymium oxide films, hafnium oxide films, tantalum oxide films, cerium oxide films, gallium zinc oxide films, and hafnium aluminate films. Examples of nitride insulating films include silicon nitride films and aluminum nitride films. Examples of oxidative nitride insulating films include silicon oxidative nitride films, aluminum oxidative nitride films, gallium oxidative nitride films, yttrium oxidative nitride films, and hafnium oxidative nitride films. Examples of nitride oxide insulating films include silicon oxidative nitride films and aluminum oxidative nitride films. Furthermore, organic insulating films can also be used for the insulating layer of semiconductor devices.

[0269] In this specification, "oxide-nitride" refers to a material in which the oxygen content is greater than the nitrogen content, and "nitride oxide" refers to a material in which the nitrogen content is greater than the oxygen content. For example, when "silicon oxynitride" is written, it refers to a material in which the oxygen content is greater than the nitrogen content, and when "silicon nitride oxide" is written, it refers to a material in which the nitrogen content is greater than the oxygen content. The content of each element can be measured using, for example, the Rutherford backscattering spectroscopy (RBS).

[0270] For example, as transistors become smaller and more integrated, thinning of the gate insulating layer can lead to problems such as leakage current. By using high-k materials for insulating layers that function as gate insulating layers, such as insulating layer 204 and insulating layer 264, it becomes possible to lower the voltage during transistor operation while maintaining the physical film thickness. Furthermore, it becomes possible to thin the equivalent oxide film thickness (EOT) of the gate insulating layer. On the other hand, by using materials with a low relative permittivity for insulating layers that function as interlayer films, parasitic capacitance between wiring can be reduced. Therefore, it is crucial to select materials according to the function of the insulating layer. It should be noted that materials with a low relative permittivity also have high dielectric strength.

[0271] Examples of materials with a high dielectric constant (high-k) include aluminum oxide, gallium oxide, hafnium oxide, tantalum oxide, zirconium oxide, hafnium-zirconium oxide, oxides containing aluminum and hafnium, oxides containing aluminum and hafnium, oxides containing silicon and hafnium, oxides containing silicon and hafnium, and nitrides containing silicon and hafnium.

[0272] Examples of materials with low dielectric constant include inorganic insulating materials such as silicon oxide, silicon oxide-nitride, and silicon nitride-oxide, as well as resins such as polyester, polyolefin, polyamide (nylon, aramid, etc.), polyimide, polycarbonate, and acrylic resin. Other inorganic insulating materials with low dielectric constant include, for example, silicon oxide with added fluorine, silicon oxide with added carbon, and silicon oxide with added carbon and nitrogen. Also, for example, silicon oxide with voids is another example. These silicon oxides may contain nitrogen.

[0273] [Conductive Layers] For the conductive layers used in the transistor 200 (conductive layers 205, 208, 219, 255, 267, 261, 265, 505, 545, 560, etc.), it is preferable to use a metal element selected from aluminum, chromium, copper, silver, gold, platinum, zinc, tantalum, nickel, titanium, iron, cobalt, molybdenum, tungsten, hafnium, vanadium, niobium, manganese, magnesium, zirconium, beryllium, indium, ruthenium, iridium, strontium, lanthanum, etc., or an alloy composed of the aforementioned metal elements, or an alloy combining the aforementioned metal elements. As alloys composed of the aforementioned metal elements, it is possible to use nitrides of the alloy or oxides of the alloy. For example, it is preferable to use tantalum nitride, titanium nitride, 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. It is also possible to use semiconductors with high electrical conductivity, such as polycrystalline silicon containing impurity elements such as phosphorus, and silicides such as nickel silicide.

[0274] Furthermore, conductive materials containing nitrogen, such as nitrides containing tantalum, nitrides containing titanium, nitrides containing molybdenum, nitrides containing tungsten, nitrides containing ruthenium, nitrides containing tantalum and aluminum, or nitrides containing titanium and aluminum; conductive materials containing oxygen, such as oxides containing ruthenium oxide, strontium and ruthenium, or oxides containing lanthanum and nickel; and materials containing metallic elements such as titanium, tantalum, or ruthenium are preferred because they are conductive materials that are resistant to oxidation, conductive materials that have the function of suppressing oxygen diffusion, or materials that maintain conductivity even when absorbing oxygen. Examples of conductive materials containing oxygen include indium oxide containing tungsten oxide, indium oxide containing titanium oxide, indium tin oxide (also known as ITO), indium tin oxide containing titanium oxide, silicon-added indium tin oxide (also known as ITSO), indium zinc oxide (also known as IZO®), and indium zinc oxide containing tungsten oxide. In this specification, a conductive layer formed using an oxygen-containing conductive material may be referred to as an oxide conductive layer.

[0275] Conductive materials mainly composed of tungsten, copper, or aluminum are preferred because they have high conductivity.

[0276] Furthermore, it is possible to use multiple conductive layers formed from the above materials in a laminated structure. For example, it is possible to create a laminated structure by combining the aforementioned metal element material with an oxygen-containing conductive material. It is also possible to create a laminated structure by combining the aforementioned metal element material with a nitrogen-containing conductive material. Furthermore, it is also possible to create a laminated structure by combining the aforementioned metal element material with an oxygen-containing conductive material and a nitrogen-containing conductive material.

[0277] For example, when using an oxide semiconductor, which is a type of metal oxide, for the semiconductor layer 203 of transistor 200A or transistor 200B, it is preferable to use a laminated structure that combines a material containing the aforementioned metal element and a conductive material containing oxygen for conductive layers that function as gate electrodes, such as conductive layer 205 and conductive layer 219. In this case, it is preferable to provide the conductive material containing oxygen on the semiconductor layer 203 side. By providing the conductive material containing oxygen on the semiconductor layer 203 side, oxygen detached from the conductive material is more easily supplied to the channel formation region of the semiconductor layer 203.

[0278] When an oxide semiconductor, which is a type of metal oxide, is used as semiconductor layer 203, semiconductor layer 263, or semiconductor layer 520, conductive layers 208a, 208b, 255, 261, 542a, and 542b are conductive layers that come into contact with semiconductor layer 203, semiconductor layer 263, or semiconductor layer 520, respectively. Therefore, it is preferable to use conductive materials that are resistant to oxidation, conductive materials that maintain low electrical resistance even when oxidized, conductive metal oxides (also called oxide conductors), or conductive materials that have the function of suppressing oxygen diffusion. Examples of such conductive materials include conductive materials containing nitrogen and conductive materials containing oxygen. This makes it possible to suppress the decrease in conductivity of conductive layers 208a, 208b, 255, 261, 542a, and 542b.

[0279] By using conductive materials containing oxygen as conductive layers 208a, 208b, 255, 261, 542a, and 542b, conductivity can be maintained even if conductive layers 208a, 208b, 255, 261, 542a, and 542b absorb oxygen. For example, even when an insulating layer containing excess oxygen is used as an insulating layer in contact with conductive layers 208a, 208b, 255, 261, 542a, and 542b, conductivity can be maintained, making this method preferable. For example, ITO, ITSO, IZO (registered trademark), etc., can be used as conductive layers 208a, 208b, 255, 261, 542a, and 542b, respectively.

[0280] [Semiconductor Layer] As semiconductor layers (semiconductor layer 203, semiconductor layer 263, semiconductor layer 520, etc.), single-crystal semiconductors, polycrystalline semiconductors, microcrystalline semiconductors, or amorphous semiconductors can be used individually or in combination. As semiconductor materials, for example, silicon and germanium can be used. Compound semiconductors such as silicon germanium, silicon carbide, gallium arsenide, and nitride semiconductors can also be used. As compound semiconductors, organic materials with semiconductor properties or metal oxides with semiconductor properties (also called oxide semiconductors) can be used. It is also possible to include impurities as dopants in these semiconductor materials.

[0281] Furthermore, semiconductors composed of single elements or compound semiconductors can be used as the semiconductor layer. Examples of semiconductors composed of single elements include silicon and germanium. Examples of compound semiconductors include gallium arsenide and silicon germanium. Other examples of compound semiconductors include organic semiconductors and nitride semiconductors. Oxide semiconductors are also a type of compound semiconductor. It is also possible to include impurities as dopants in these semiconductor materials.

[0282] When silicon is used as a semiconductor layer, examples of silicon that can be used for the semiconductor layer include single-crystal silicon, polycrystalline silicon, microcrystalline silicon, and amorphous silicon. As an example of polycrystalline silicon, low-temperature polysilicon (LTPS) is used.

[0283] For example, by using silicon for the semiconductor layer 203 of transistor 200A or transistor 200B, and including phosphorus or arsenic as an n-type dopant in regions 203a and 203c of the semiconductor layer 203, it is possible to make the transistor function as an n-type transistor. Alternatively, by including boron as a p-type dopant in regions 203a and 203c of the semiconductor layer 203, it is possible to make the transistor function as a p-type transistor. When both n-type and p-type dopants are included in regions 203a and 203c of the semiconductor layer 203, the conductivity type with the higher dopant concentration is more likely to manifest.

[0284] It is also possible to use a two-dimensional material that functions as a semiconductor as the semiconductor layer of a transistor. Two-dimensional materials, also called layered materials, are a general term for a group of materials that have a layered crystalline structure. Layered materials have high electrical conductivity within a unit layer, that is, high two-dimensional electrical conductivity. By using a material that functions as a semiconductor and has high two-dimensional electrical conductivity as the semiconductor layer, it is possible to provide a transistor with a large on-current.

[0285] Examples of the above-mentioned layered materials include graphene, silicene, and chalcogenides. Chalcogenides are compounds containing chalcogens (elements belonging to Group 16). Examples of chalcogenides include transition metal chalcogenides and Group 13 chalcogenides. Specifically, a transition metal chalcogenide applicable as a semiconductor layer in transistors is molybdenum sulfide (typically MoS ２ ), molybdenum selenide (typically MoSe ２ ), molybdenum tellurium (typically MoTe ２ ), tungsten sulfide (typically WS ２), tungsten selenide (typically WSe ２ ), tungsten tellurium (typically WTe ２ ), hafnium sulfide (typically HfS ２ ), hafnium selenide (typically HfSe ２ ), zirconium sulfide (typically ZrS ２ ), zirconium selenide (typically ZrSe ２ ) are some examples.

[0286] When using an oxide semiconductor, a type of metal oxide, as the semiconductor layer, the band gap of the metal oxide is preferably larger than that of silicon (typically 1.1 eV), preferably 2.0 eV or larger, and more preferably 2.5 eV or larger. By using a metal oxide with a larger band gap than silicon as the semiconductor layer, the off-current of the transistor can be significantly reduced. Because OS transistors have a small off-current, the power consumption of semiconductor devices can be reduced.

[0287] The metal oxide that can be used in the semiconductor layer of an OS transistor preferably contains at least indium (In). Furthermore, it is preferable that the metal oxide contains at least one of indium (In) or zinc (Zn). Moreover, it is preferable that the metal oxide contains two or three elements selected from indium, element M, and zinc. Element M is a metal or metalloid element with a high bond energy with oxygen, for example, a metal or metalloid element with a higher bond energy with oxygen than indium.

[0288] Specific examples of element M include aluminum, gallium, tin, yttrium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, zirconium, molybdenum, hafnium, tantalum, tungsten, lanthanum, cerium, neodymium, magnesium, calcium, strontium, barium, boron, silicon, germanium, and antimony. The element M contained in the metal oxide is preferably one or more of the above elements, more preferably one or more selected from aluminum, gallium, tin, and yttrium, and even more preferably gallium.

[0289] For example, indium oxide (In oxide, indium oxide) can be used as a metal oxide for the semiconductor layer of an OS transistor. Other metal oxides include zinc oxide (Zn oxide, zinc oxide), indium zinc oxide (In-Zn oxide), indium tin oxide (In-Sn oxide), indium titanium oxide (In-Ti oxide), indium gallium oxide (In-Ga oxide), indium gallium aluminum oxide (In-Ga-Al oxide), indium gallium tin oxide (In-Ga-Sn oxide), gallium zinc oxide (Ga-Zn oxide, also written as "GZO"), aluminum zinc oxide (Al-Zn oxide, also written as "AZO"), and indium Aluminum zinc oxide (In-Al-Zn oxide, also written as "IAZO"), indium tin zinc oxide (In-Sn-Zn oxide), indium titanium zinc oxide (In-Ti-Zn oxide), indium gallium zinc oxide (In-Ga-Zn oxide, also written as "IGZO"), indium gallium tin zinc oxide (In-Ga-Sn-Zn oxide, also written as "IGZTO"), indium gallium aluminum zinc oxide (In-Ga-Al-Zn oxide, also written as "IGAZO" or "IAGZO"), etc., can be used. Alternatively, silicon-containing indium tin oxide, gallium tin oxide (Ga-Sn oxide), aluminum tin oxide (Al-Sn oxide), etc., can be used.

[0290] Examples of crystal structures for metal oxides that function as semiconductors include amorphous (including completely amorphous), CAAC (c-axis-aligned crystalline), nc (nanocrystalline), single crystal, and polycrystalline.

[0291] Furthermore, by increasing the ratio of zinc atoms to the sum of the atoms of other metal elements in a metal oxide that functions as a semiconductor, a highly crystalline metal oxide can be obtained, suppressing the diffusion of impurities within the metal oxide. Consequently, fluctuations in the electrical properties of the transistor can be suppressed, improving reliability.

[0292] Furthermore, by increasing the ratio of element M atoms to the sum of the atoms of metal elements among the main constituent elements contained in the metal oxide, the formation of oxygen vacancies in the metal oxide can be suppressed. Therefore, carrier generation caused by oxygen vacancies is suppressed, resulting in a transistor with low off-current. In addition, fluctuations in the electrical characteristics of the transistor are suppressed, and reliability can be improved.

[0293] The field-effect mobility of a transistor can be increased by increasing the ratio of indium atoms to the sum of the total number of atoms of all metal elements contained in the metal oxide. Typically, using single-crystal or polycrystalline indium oxide in the semiconductor layer can significantly increase the field-effect mobility of a transistor. Furthermore, transistors using single-crystal or polycrystalline indium oxide in the semiconductor layer can achieve good frequency characteristics.

[0294] The configuration shown in this embodiment can be used in appropriate combination with the configurations shown in other embodiments.

[0295] (Embodiment 4) This embodiment describes an indium oxide film that can be used in the semiconductor layer of a transistor in a semiconductor device according to one aspect of the present invention.

[0296] In this specification, indium oxide having at least a crystalline portion or crystalline region in the film is referred to as crystalline indium oxide (crystal IO) or crystalline indium oxide (crystalline IO). Examples of crystal IO or crystalline IO include single-crystal indium oxide, polycrystalline indium oxide, and microcrystalline indium oxide.

[0297] Indium oxide is a semiconductor material with completely different physical properties from oxide semiconductors such as In-Ga-Zn oxide (hereinafter also referred to as IGZO) and zinc oxide.

[0298] This paper describes the carrier concentration dependence of the hole mobility of indium oxide, silicon, and IGZO.

[0299] IGZO tends to exhibit higher hole mobility as the carrier concentration increases. On the other hand, single-crystal indium oxide tends to exhibit higher hole mobility as the carrier concentration decreases. This trend is similar to that of silicon, where lower dopant (impurity) concentrations in the material reduce impurity scattering and increase hole mobility. In other words, the higher the purity and intrinsic nature of single-crystal indium oxide, the higher its hole mobility. From these results, it can be said that single-crystal indium oxide, unlike IGZO, is a material with physical properties similar to silicon. Note that when indium oxide is not single-crystal (e.g., polycrystalline), the trend may differ from that of single crystals.

[0300] The range of carrier concentrations suitable for the channel formation region of a transistor is 1 × 10⁻⁶. １５ cm −３ This range includes, for example, 1 × 10 １４ cm −３ The above is 1 x 10 １８ cm −３ The range is as follows: By sufficiently reducing the carrier concentration, the hole mobility value can be increased to 270 cm⁻¹. ２ It can be expected to be raised to the level of / (V・s).

[0301] Indium oxide can contain elements that lower the carrier concentration. Examples of elements that lower the carrier concentration include magnesium, calcium, zinc, cadmium, and copper. These elements can lower the carrier concentration by substituting for indium. Other examples include nitrogen, phosphorus, arsenic, and antimony. These elements can lower the carrier concentration by substituting for oxygen.

[0302] On the other hand, electrical resistance can be reduced by increasing the carrier concentration. For example, the suitable carrier concentration range for the source and drain regions of a transistor, or for a resistor or transparent conductive film, is when the carrier concentration value is 1 × 10⁻⁶ ２０ cm −３ This range includes, for example, 1 × 10 １９ cm −３ The above is 1 x 10 ２２ cm −３ The range is as follows: By making the carrier concentration sufficiently high, the resistivity can be increased to 1 × 10⁻⁶. −４ It is expected that the level can be reduced to below Ω·cm.

[0303] Indium oxide may contain elements that increase the carrier concentration. For example, it is preferable to include elements common to the source and drain electrodes of the transistor. Examples of elements that increase the carrier concentration include titanium, zirconium, hafnium, tantalum, tungsten, molybdenum, tin, silicon, and boron. In particular, it is more preferable to use elements in which the oxide is conductive or semiconducting.

[0304] Because indium oxide is an oxide whose valence electrons can be controlled, the region with a low carrier concentration can be used for the channel formation region of the transistor, and the region with a high carrier concentration can be used for the source and drain regions of the transistor. This makes it possible to create a so-called n-i-n junction (a junction between an n-type region, an i-type region, and an n-type region). Valence electron control in transistors using silicon is generally known. On the other hand, valence electron control in transistors using indium oxide is a novel technological concept that would not normally be conceived. By using this technological concept, it is possible to realize a transistor with high mobility, low off-current, normally-off capability, and high reliability.

[0305] The indium oxide film is preferably crystalline. In particular, the indium oxide film is preferably polycrystalline, and more preferably single-crystal. A single-crystal film does not have grain boundaries. By using a single-crystal film, carrier scattering at grain boundaries can be suppressed, enabling the realization of transistors that exhibit high field-effect mobility. Furthermore, it has the excellent effect of suppressing variations in transistor characteristics caused by these grain boundaries.

[0306] Furthermore, polycrystalline films are preferable because they can reduce carrier scattering and exhibit high field-effect mobility compared to microcrystalline or amorphous films. When using polycrystalline films, it is preferable to use films with the largest possible grain size and few grain boundaries. In a transistor to which a polycrystalline film is applied, if there are no grain boundaries in the channel formation region, or if no grain boundaries are observed, the channel formation region is located within the single-crystal region contained in the polycrystalline film, and therefore it can be considered a transistor to which a single-crystal film is applied.

[0307] The crystallinity of indium oxide can be analyzed, for example, by X-ray diffraction (XRD), transmission electron microscopy (TEM), or electron diffraction (ED). Alternatively, a combination of these methods may be used for analysis.

[0308] Furthermore, in this specification, a semiconductor layer in which no grain boundaries are observed in the channel formation region, a semiconductor layer in which the channel formation region is contained within a single crystal grain, or a semiconductor layer in which the crystal axis directions are the same in at least two regions within the channel formation region can be considered as a single crystal film.

[0309] The channel formation region refers to the region of the semiconductor layer that overlaps with (or faces) the gate electrode via the gate insulating layer, and is located between the region in contact with the source electrode and the region in contact with the drain electrode. The crystal grains, grain boundaries, crystal axes, and crystal orientation in the channel formation region can be confirmed by cross-sectional observation including the semiconductor layer, source electrode, and drain electrode.

[0310] Impurities in the indium oxide film can act as a source of carrier scattering, thus potentially causing a decrease in field-effect mobility and inhibiting crystal growth. Examples of impurities in the indium oxide film include boron and silicon. In the channel-forming region of the indium oxide film, lower concentrations of these impurities are preferable. For example, the concentration of each of the above impurity elements should be 0.1% or less, more preferably 0.01% (100 ppm) or less. Note that elements such as carbon and hydrogen may be present in the deposition gas or precursor during film formation, and may remain in the indium oxide film in higher concentrations than the above impurities.

[0311] Furthermore, the indium oxide film may contain elements that can become trivalent cations like indium, as long as their crystals maintain a cubic crystal structure (Bixbite type). Examples include Group 13 elements of the periodic table such as gallium and aluminum, and Group 3 elements of the periodic table. Since these elements mainly exist as trivalent cations in the oxide, the carrier concentration of indium oxide can be kept low.

[0312] By using such an indium oxide film in a transistor, the field-effect mobility of the transistor can be increased to 50 cm². ２ / (V·s) or more, preferably 100 cm ２ / (V·s) or more, more preferably 150 cm ２ / (V·s) or more, more preferably 200 cm ２ / (V·s) or more, more preferably 250 cm ２ It can be set to (V・s) or more.

[0313] One of the characteristics of indium oxide films is their higher oxygen permeability (diffusivity) compared to IGZO films. For example, oxygen diffusing into an indium oxide film permeates the film and is released as oxygen molecules. In some cases, it may also be released as water molecules by reacting with hydrogen contained in the film. Furthermore, if there is an oxygen deficiency in the film, diffusing oxygen atoms will fill the deficiency. Because oxygen diffuses easily through indium oxide films, it can be said that oxygen deficiencies are more easily filled in compared to IGZO films.

[0314] Thus, because indium oxide films are more likely to reduce oxygen vacancies in the film compared to IGZO films, applying such indium oxide films to transistors makes it possible to realize transistors with extremely high reliability.

[0315] Furthermore, the indium oxide film diffuses hydrogen. Hydrogen diffusing into the indium oxide film from the outside permeates the film and is released as hydrogen molecules. Alternatively, it reacts with oxygen contained in the film and is released as water molecules.

[0316] Indium oxide is characterized by a small effective electron mass and a large effective hole mass. Furthermore, the effective electron mass of indium oxide is largely independent of the crystal orientation. Therefore, using crystalline indium oxide in transistors allows for the realization of transistors with high field-effect mobility and high frequency characteristics (also known as f-response). Moreover, due to the large effective hole mass, transistors with extremely low off-currents can be realized. For example, by applying an indium oxide film to a transistor, the off-current per 1 μm of channel width is 1 fA (1 × 10⁻¹⁶) at 125°C. −１５ A) Less than or equal to, or 1aA (1 × 10 −１８ A) Less than or equal to 1aA (1 × 10) in a room temperature (25°C) environment. −１８ A) Less than or equal to, or 1zA (1 × 10⁻¹⁰−２１ A) The following is possible. Furthermore, because indium oxide has a smaller effective electron mass and a larger effective hole mass than silicon, it may be possible to realize transistors with higher field-effect mobility and lower off-current than Si transistors.

[0317] It is preferable to provide a seed layer so as to be in contact with at least a portion of the crystalline indium oxide film. It is preferable to use a material containing crystals with a small difference in lattice constant (also called lattice mismatch) with the indium oxide for the seed layer. This improves the crystallinity of the indium oxide film. A substrate (e.g., a single-crystal substrate) may be used as one of the layers in contact with at least a portion of the crystalline indium oxide film.

[0318] One method for evaluating the degree of lattice mismatch is to use the following lattice mismatch value. The lattice mismatch Δa [%] of the crystals in the formed film (in this case, the indium oxide film) relative to the crystals in the seed layer is given by Δa = ((L １ -L ２ ) / L ２ It is calculated as ) × 100. Here L １ L is the length of the unit cell vector of the crystals in the formed film, or the lattice constant. ２ This is the length of the unit cell vector of the crystal in the seed layer, or the lattice constant.

[0319] The lattice mismatch Δa between the seed layer and the indium oxide film is preferably small in absolute value, and most preferably zero. For example, Δa can be -5% or more and 5% or less, preferably -4% or more and 4% or less, more preferably -3% or more and 3% or less, and even more preferably -2% or more and 2% or less.

[0320] Here, the indium oxide crystal has a cubic structure (bixbite type). For example, yttria-stabilized zirconia (YSZ) crystals can have a cubic structure (fluorite type). The lattice mismatch of the indium oxide crystal with respect to the cubic YSZ crystal is in the range of -2% to 2%, and a single crystal film of indium oxide can be epitaxially grown on a YSZ substrate.

[0321] Furthermore, the crystal structure of the seed layer and the crystal structure of the indium oxide film do not necessarily have to be the same in terms of crystal system or crystal orientation. For example, a film with a hexagonal or trigonal crystal structure can be used beneath an indium oxide film with a cubic crystal structure. For example, by setting the crystal orientation of the surface of the seed layer to

[001] and the crystal orientation of the underside of the indium oxide film to

[111] , the requirements related to crystal orientation necessary for epitaxial growth can be met. Examples of hexagonal or trigonal crystals include wurtzite-type structures and YbFe. ２ O ４ Type structure, Yb ２ Fe ３ O ７ These include type structures and their modified type structures. YbFe ２ O ４ Type structure or Yb ２ Fe ３ O ７ An example of a crystal having a type structure is IGZO.

[0322] The configuration shown in this embodiment can be used in appropriate combination with the configurations shown in other embodiments.

[0323] (Embodiment 5) An example of a planar layout and an example of a cross-sectional structure of the semiconductor device 10 will be described. In this embodiment, an example of a planar layout and an example of a cross-sectional structure of the semiconductor device 10A shown in Figure 1A will be described.

[0324] In this embodiment, we will describe the case where transistor 200A (see Figures 18A to 18C) shown in Embodiment 3 is used as transistor Tr1, and transistors 200B (see Figures 19A to 19C) are used as transistors Tr2 and TrD. Furthermore, in order to reduce repetition of explanation, we will mainly describe matters not shown in other embodiments. Matters not shown in this embodiment can be referred to in other embodiments.

[0325] Figure 24 is a diagram showing an example of a planar layout of the semiconductor device 10A shown in Figure 1A. Figure 25 is an enlarged view of the area including transistors Tr1, Tr2, and TrD shown in Figure 24. Figure 26A is a cross-sectional view between A1 and A2, shown by the dashed line in Figure 25. Figure 26B is a cross-sectional view between A2 and A3, shown by the dashed line in Figure 25. Figure 27A is a cross-sectional view between A3 and A4, shown by the dashed line in Figure 25. Figure 27B is a cross-sectional view between A5 and A6, shown by the dashed line in Figure 24.

[0326] The semiconductor device 10A shown in this embodiment has insulating layers 202, 229, 204, 206, 209, and 228. It also has conductive layers 219 (conductive layer 219[2], conductive layer 219[D]), conductive layer 205 (conductive layer 205[1], conductive layer 205[2], conductive layer 205[D]), conductive layer 214, conductive layer 215, conductive layer 221, conductive layer 222, conductive layer 223, conductive layer 224, conductive layer 225, conductive layer 226, conductive layer 227, and conductive layer 239. It also has semiconductor layers 203 (semiconductor layer 203[1], semiconductor layer 203[D]) and 233. Furthermore, the semiconductor device 10A is connected to conductive layers 211, 212, and 213.

[0327] These conductive layers can be formed using the materials shown in Embodiment 3.

[0328] In this embodiment, the semiconductor device 10A uses oxide semiconductors as the semiconductor layers for transistors Tr1 and TrD, and thin-film silicon (e.g., LTPS) as the semiconductor layer for transistor Tr2. Therefore, in this embodiment, the semiconductor layer for transistor Tr1 is shown as semiconductor layer 203[1], the semiconductor layer for transistor TrD is shown as semiconductor layer 203[D], and the semiconductor layer for transistor Tr2 is shown as semiconductor layer 233. Transistors Tr1 and TrD function as n-type transistors, and transistor Tr2 functions as a p-type transistor.

[0329] For example, an oxide semiconductor such as IGZO can be used as the semiconductor layer of transistor Tr1. Furthermore, as the transistor TrD that controls the magnitude of the current flowing through the light-emitting element 61, it is preferable to use a transistor that has a high dielectric breakdown voltage between the source and drain and a high current supply capability (high field-effect mobility). Therefore, it is preferable to use an oxide semiconductor that contains a large amount of indium in the semiconductor layer in which the channel is formed as the transistor used for transistor TrD. For example, a transistor using indium oxide in the semiconductor layer in which the channel is formed is preferred as the transistor used for transistor TrD. In particular, a transistor using crystalline indium oxide in the semiconductor layer is preferred.

[0330] The semiconductor layer 203 and the semiconductor layer 233 are formed on different insulating layers. In this embodiment, the semiconductor layer 233 is provided on the insulating layer 202. An insulating layer 229 is also provided covering the semiconductor layer 233 (see Figure 27A). The semiconductor layer 203[1] and the semiconductor layer 203[D] are provided on the insulating layer 229 (see Figures 26A and 26B).

[0331] Conductive layer 211 has a region extending along the X direction. Conductive layer 211 functions as wiring AN. Conductive layer 212 has a region extending along the X direction. Conductive layer 212 functions as wiring GL. Conductive layer 213 has a region extending along the X direction. Conductive layer 213 functions as wiring PL. Conductive layer 221 has a region extending along the Y direction. Conductive layer 221 functions as wiring SL.

[0332] The conductive layers 211, 212, 213, 214, and 215 are formed on the insulating layer 204, similar to the conductive layer 205. Therefore, the conductive layers 211, 212, 213, 214, and 215 can be formed simultaneously using the same material and process as the conductive layer 205.

[0333] The conductive layers 221, 222, 223, 224, 225, 226, 227, and 239 are formed on the insulating layer 206, similar to the conductive layer 208 shown in the above embodiment. Therefore, the conductive layers 221, 222, 223, 224, 225, 226, 227, and 239 can be formed simultaneously using the same material and process as the conductive layer 208.

[0334] The conductive layer 211 is connected to the semiconductor layer 203[D] via the conductive layer 223 (see Figures 24 and 25). The conductive layer 211 is also connected to the conductive layer 219[2] via the conductive layers 224 and 214. The conductive layer 212 is connected to the conductive layer 205[1] via the conductive layer 222. The conductive layer 213 is connected to the semiconductor layer 233 and the conductive layer 205[2] via the conductive layer 225.

[0335] Furthermore, the conductive layer 211 and the conductive layer 224 are in contact in a region that overlaps with an opening 236 provided in a part of the insulating layer 206 (Figures 24 and 27B). In this embodiment, the conductive layer 211 and the conductive layer 224 are in contact in a region that overlaps with two openings 236. By providing multiple openings that connect the two conductive layers, the contact resistance can be reduced. In addition, the manufacturing yield of semiconductor devices can be increased. Furthermore, the reliability of semiconductor devices can be improved.

[0336] The conductive layer 221 is connected to the semiconductor layer 203[1] (see Figures 24, 25, and 26A). Specifically, the conductive layer 221 is connected to the semiconductor layer 203[1] at the bottom of the opening 207a[1] that penetrates the insulating layers 204 and 206. The semiconductor layer 203[1] is also connected to the conductive layer 205(D) via the conductive layer 226. Specifically, the semiconductor layer 203[1] is connected to the conductive layer 226 at the bottom of the opening 207b[1], and the conductive layer 226 is connected to the conductive layer 205"D" at the bottom of the opening 216 that penetrates the insulating layer 206.

[0337] In this embodiment, an example is shown in which the conductive layer 221 and the semiconductor layer 203[1] are in contact at the bottom of a single opening 207a[1], but it is possible to provide multiple openings 207a[1]. By providing multiple openings 207a[1], the contact area between the conductive layer 221 and the semiconductor layer 203[1] is increased. Therefore, the contact resistance between the conductive layer 221 and the semiconductor layer 203[1] can be reduced. Note that the same effect can be obtained with other openings as well as openings 207a[1].

[0338] The region of the conductive layer 205[1] that overlaps with the semiconductor layer 203[1] functions as the gate electrode of transistor Tr1. The region of the semiconductor layer 203[1] that overlaps with the conductive layer 205[1] functions as the channel formation region of transistor Tr1. The insulating layer 204 functions as the gate insulating layer of transistor Tr1. Furthermore, a portion of the conductive layer 226 functions as either the source electrode or the drain electrode of transistor Tr1. A portion of the conductive layer 221 functions as either the source electrode or the drain electrode of transistor Tr1.

[0339] The conductive layer 239 is connected to the semiconductor layer 203[D] at the bottom of an opening that penetrates the insulating layers 204 and 206. The conductive layers 219[D] and 219[2] are provided between the substrate 201 and the insulating layer 202 (see Figures 26B and 27A). The conductive layer 219[D] is connected to the conductive layer 215 at the bottom of an opening 217 that penetrates the insulating layers 204, 229 and 202 (see Figures 24, 25 and 26B). The conductive layer 215 is connected to the conductive layer 227 at the bottom of an opening 218 that penetrates the insulating layer 206.

[0340] The region of conductive layer 205[D] that overlaps with semiconductor layer 203[D] functions as the gate electrode of transistor TrD. The region of semiconductor layer 203[D] that overlaps with conductive layer 205[D] functions as the channel formation region of transistor Tr1. Insulating layer 204 functions as the gate insulating layer of transistor TrD. The region of conductive layer 219[D] that overlaps with conductive layer 205[D] and semiconductor layer 203[D] functions as the back gate electrode of transistor TrD. Insulating layers 202 and 229 function as the back gate insulating layers ("back gate insulating layers") of transistor TrD. Furthermore, a portion of conductive layer 223 functions as either the source electrode or the drain electrode of transistor TrD. A portion of conductive layer 239 functions as either the source electrode or the drain electrode of transistor TrD.

[0341] The conductive layer 227 is connected to the semiconductor layer 233 at the bottom of an opening 207a[2] that penetrates the insulating layer 229, insulating layer 204, and insulating layer 206 (see Figures 24, 25, and 27A). The conductive layer 225 is connected to the semiconductor layer 233 at the bottom of an opening 207b[2] that penetrates the insulating layer 229, insulating layer 204, and insulating layer 206.

[0342] The region of the conductive layer 205[2] that overlaps with the semiconductor layer 233 functions as the gate electrode of transistor Tr2. Also, the region of the semiconductor layer 233 that overlaps with the conductive layer 205[2] functions as the channel formation region of transistor Tr2. The insulating layer 204 and insulating layer 229 function as gate insulating layers of transistor Tr2. Also, the region of the conductive layer 219[2] that overlaps with the conductive layer 205[2] and the semiconductor layer 233 functions as the back gate electrode of transistor Tr2. The insulating layer 202 functions as the back gate insulating layer of transistor Tr2. Also, a portion of the conductive layer 227 functions as either the source electrode or the drain electrode of transistor Tr2. A portion of the conductive layer 225 functions as either the source electrode or the drain electrode of transistor Tr2.

[0343] Furthermore, the region where the conductive layer 205[D] and the conductive layer 239 overlap via the insulating layer 206 functions as a capacitive element C1 (see Figure 24). Also, the region where the conductive layer 215 and the conductive layer 239 overlap via the insulating layer 206 functions as a capacitive element C2. In addition, the conductive layer 239 is connected to one terminal of the light-emitting element 61.

[0344] In this embodiment, a configuration is shown in which an insulating layer 228 having a flat upper surface is provided on top of the insulating layer 209 (see Figures 26A, 26B, and 27A). An insulating layer having an organic material is preferred for the insulating layer 228. For example, acrylic resin, polyimide, polyamide, polyimidoamide, epoxy resin, siloxane resin, benzocyclobutene resin, phenol resin, or precursors of these resins can be used as the insulating layer 228. Alternatively, the insulating layer 228 may be formed from an inorganic material, and the upper surface of the insulating layer 228 may be subjected to CMP treatment. By reducing the unevenness of the upper surface of the insulating layer 228, the coverage of the insulating layer and conductive layer formed thereafter can be improved.

[0345] As mentioned above, it is preferable that the channel length of transistor TrD, which functions as a drive transistor, is long. For example, it is preferable that the channel length Ld of transistor TrD is longer than the channel length L1 of transistor Tr1, which functions as a switch (see Figures 25 and 26A). By increasing the channel length Ld of transistor TrD, which functions as a drive transistor, the reproducibility of the luminescence brightness of the light-emitting element 61 in relation to the video signal Vdata can be improved.

[0346] Furthermore, by reducing the characteristic variation of transistor Tr2, the Vth variation of transistor TrD can be corrected with greater accuracy. To reduce the characteristic variation of transistor Tr2, it is preferable that the transistor size of transistor Tr2 is large. Specifically, it is preferable that the channel length L2 of transistor Tr2 is larger than the channel length L1 of transistor Tr1 which functions as a switch (see Figures 25, 26A, and 27A). It is also preferable that the channel width W2 of transistor Tr2 is larger than the channel width W1 of transistor Tr1 which functions as a switch.

[0347] The conductive layers 211, 212, 213, and 221 connected to the semiconductor device 10A function as power supply lines or signal lines. It is preferable that the width of these conductive layers is greater than the width of the conductive layers branched from them and used as routing lines. For example, in the semiconductor device 10A shown in Figure 24, it is preferable that the width Wp of the conductive layer 211, which functions as wiring AN, is greater than the width Ws of the conductive layer 223. This reduces the power supply capacity and signal delay of the conductive layers functioning as power supply lines or signal lines, enabling stable operation of the semiconductor device 10A. Therefore, the reliability of the semiconductor device 10A can be improved.

[0348] Furthermore, it is preferable to reduce the overlapping area of ​​the two wirings at the intersection of the two wirings. For example, Figure 24 shows an example where the width of conductive layer 211 at the intersection of conductive layer 211 and conductive layer 221 is set to a width Wc that is smaller than the width Wp. It is also possible to reduce the width of conductive layer 221 at the intersection of conductive layer 211 and conductive layer 221. It is also possible to reduce the width of both conductive layer 211 and conductive layer 221 at the intersection of conductive layer 211 and conductive layer 221.

[0349] By reducing the overlapping area of ​​the conductive layer 211 and the conductive layer 221, parasitic capacitance between the two wirings can be reduced. Therefore, the power consumption of the semiconductor device 10 can be reduced. In addition, signal delays and other issues can be reduced, allowing the semiconductor device 10 to operate stably. Therefore, the reliability of the semiconductor device 10 can be improved.

[0350] Furthermore, in a semiconductor device 10 according to one aspect of the present invention, if there are two or more transistors made of different materials in the semiconductor layer including the channel formation region, and these transistors are provided on different layers, then a part of the components of the transistor provided on the lower layer and a part of the components of the transistor provided on the upper layer may be formed in the same process.

[0351] For example, if the semiconductor device 10 has an Si transistor and an OS transistor, the layer on which the OS transistor is provided can be arranged on top of the layer on which the Si transistor is provided. In this case, for example, a part of the components of the Si transistor provided in the lower layer and a part of the components of the OS transistor provided in the upper layer may be formed in the same process. For example, a conductive layer that functions as a source electrode, drain electrode, etc. of the Si transistor provided in the lower layer and a conductive layer that functions as a back gate electrode of the OS transistor provided in the upper layer may be formed in the same process. For example, a conductive layer that functions as a gate electrode of the Si transistor provided in the lower layer and a conductive layer that functions as a back gate electrode of the OS transistor provided in the upper layer may be formed in the same process.

[0352] As an example, Figure 28A shows a cross-sectional configuration example of a semiconductor device 600 in which an element layer 620 containing an OS transistor, TrOS, is superimposed on an element layer 610 containing a Si transistor, TrSi. The transistor TrSi includes a conductive layer 611 that functions as a back gate electrode, a semiconductor layer 612, a conductive layer 613 that functions as a gate electrode, a conductive layer 614a that functions as either a source electrode or a drain electrode, and a conductive layer 614b that functions as the other source electrode or drain electrode. Furthermore, a conductive layer 621 is provided on the same layer as the conductive layer 614 (conductive layer 614a, conductive layer 614b).

[0353] The transistor TrOS includes a semiconductor layer 622, a conductive layer 623 that functions as a gate electrode, a conductive layer 624a that functions as either a source electrode or a drain electrode, and a conductive layer 624b that functions as the other source electrode or drain electrode. A conductive layer 621 provided on the element layer 610 functions as the back gate electrode of the transistor TrOS.

[0354] The conductive layer 621 can be formed using the same process as the conductive layer 614. Therefore, the manufacturing process for semiconductor devices is reduced, and the productivity of semiconductor devices can be increased.

[0355] Furthermore, in the semiconductor device 600 shown in Figure 28B, the conductive layer 614a also functions as the back gate electrode of the transistor TrOS. Because the conductive layer 614a functions as either the source electrode or the drain electrode of the transistor TrSi, and also as the back gate electrode of the transistor TrOS, the formation of the conductive layer 621 can be eliminated. Therefore, the occupied area of ​​the semiconductor device 600 is reduced, and the mounting density of the semiconductor device 600 can be increased.

[0356] The configuration shown in this embodiment can be used in appropriate combination with the configurations shown in other embodiments.

[0357] (Embodiment 6) A semiconductor device according to one aspect of the present invention can be applied to a display device and the like. Furthermore, a semiconductor device according to one aspect of the present invention can be applied to a module having said display device (also referred to as a "display module"). In this embodiment, a display device having a semiconductor device according to one aspect of the present invention will be described.

[0358] Examples of display modules include modules with connectors such as flexible printed circuit boards (FPC) or TCP (Tape Carrier Package) attached to the display device, or modules on which integrated circuits (ICs) are mounted using methods such as COG (Chip On Glass) or COF (Chip On Film).

[0359] <Example of Display Device Configuration> Figure 29A is a perspective view showing an example of the configuration of a display device 400 according to one aspect of the present invention.

[0360] The display device 400 has a configuration in which substrate 411 and substrate 451 are bonded together. In Figure 29A, substrate 411 is shown with a dashed line.

[0361] The display device 400 has a display unit 452, a circuit unit 454a, a circuit unit 454b, a connection unit 457, and a wiring unit 458. Figure 29A shows an example in which IC 456 and FPC 459 are mounted on the display device 400. Therefore, the configuration shown in Figure 29A can also be described as a display module having the display device 400, an IC, and an FPC.

[0362] Circuit section 454a includes, for example, a scan line drive circuit (also called a gate driver or scan driver). Circuit section 454b includes, for example, a signal line drive circuit (also called a source driver or data driver). The scan line drive circuit has the function of supplying potential to wiring AN, wiring GL, and wiring PL. It is also possible to provide a dedicated drive circuit for each of wiring AN, wiring GL, and wiring PL.

[0363] The wiring section 458 has the function of supplying signals and power to the display section 452, the circuit section 454a, and the circuit section 454b. These signals and power are input to the wiring section 458 from outside the display device 400 via the FPC 459, or from the IC 456.

[0364] Figure 29A shows an example in which IC 456 is provided on the substrate 451 using a COG (Cambodia Grading) or COF (Cambodia Frame) method. For example, IC 456 can be an IC having one or both of a scan line drive circuit and a signal line drive circuit. Note that the display device 400 and the display module can be configured without an IC. It is also possible to mount IC 456 on an FPC (Flexible Printed Circuit) using a COF method or the like.

[0365] Furthermore, it is possible to configure a scan line drive circuit using either or both of IC 456 and circuit section 454a. In this case, IC 456 may be referred to as a gate driver IC. Also, it is possible to configure a signal line drive circuit using either or both of IC 456 and circuit section 454b. In this case, IC 456 may be referred to as a source driver IC.

[0366] The display unit 452 is the area in the display device 400 that displays images, and has a plurality of pixels 455 arranged periodically. Figure 29A shows a magnified view of one pixel 455.

[0367] The pixel 455 shown in Figure 29A has a pixel 453R that emits red (R) light, a pixel 453G that emits green (G) light, and a pixel 453B that emits blue (B) light. Full-color display can be achieved by configuring one pixel 455 with pixels 453R, 453G, and 453B. Pixels 453R, 453G, and 453B each function as sub-pixels. The display device 400 shown in Figure 29A shows an example where the sub-pixels 453R, 453B, and 453G are arranged in a stripe pattern. Note that the number of sub-pixels constituting one pixel 455 is not limited to three, but can be four or more. For example, it is possible to have four sub-pixels that emit R, G, B, and white (W) light, respectively. Alternatively, it is possible to have four sub-pixels that emit R, G, B, and yellow (Y) light, respectively.

[0368] In this specification, elements related to red light may be denoted with the identification code "R," elements related to green light with the identification code "G," and elements related to blue light with the identification code "B" to describe their respective aspects. Conversely, common aspects may be described by not assigning these identification codes. For example, when it is necessary to distinguish between multiple pixels 453, they may be indicated as pixel 453R, pixel 453G, or pixel 453B. Also, when it is not necessary to distinguish between pixels 453R, 453G, and 453B, they may simply be indicated as pixel 453.

[0369] Each of the pixels 453R, 453G, and 453B includes a light-emitting element and a circuit (pixel circuit) that controls the luminescence brightness of the light-emitting element. A semiconductor device 10 according to one embodiment of the present invention can be used as pixel 453.

[0370] The connection portion 457 is provided on the outside of the display portion 452. The connection portion 457 can be provided along one or more sides of the display portion 452. There may be one or more connection portions 457. Figure 29A shows an example in which the connection portion 457 is provided so as to surround all four sides of the display portion. The connection portion 457 connects the common electrode of the display element to the wiring portion 458, and can supply potential to the common electrode.

[0371] Here, for example, the transistors shown in the above embodiment can be used in at least a portion of the display unit 452, circuit unit 454a, and circuit unit 454b of the display device 400.

[0372] For example, by using vertical transistors such as the transistor 200C described above in one or both of the circuit sections 454a and 454b, the occupied area of ​​the circuit sections 454a and 454b can be reduced, resulting in a display device with a narrow bezel.

[0373] Furthermore, by using vertical transistors such as the transistor 200C or transistor 200D described above in the pixel circuit of the display unit 452, for example, the occupied area of ​​the pixel circuit can be reduced, and the resolution of the display device can be increased. For example, a display device with a resolution of 300 ppi or more, 500 ppi or more, 1000 ppi or more, 2000 ppi or more, or 3000 ppi or more can be realized.

[0374] Furthermore, a display device according to one aspect of the present invention may also function as a touch panel. For example, various detection elements (also called sensor elements) capable of detecting the proximity or contact of an object to be detected, such as a finger, can be applied to the display device.

[0375] Examples of sensor types include capacitive, resistive, surface acoustic wave, infrared, optical, and pressure-sensitive sensors.

[0376] Examples of capacitance methods include surface capacitance and projected capacitance. Examples of projected capacitance methods include self-capacitance and mutual capacitance. Mutual capacitance is preferred because it enables simultaneous multi-point detection.

[0377] Examples of touch panels include out-cell, on-cell, and in-cell types. An in-cell touch panel refers to a configuration in which electrodes constituting a sensing element are provided on one or both of the substrate supporting the display element (also called a display device) and the opposing substrate.

[0378] [Pixel Arrangement] Figures 29B to 29F are plan views illustrating the pixel arrangement. In a display device according to one aspect of the present invention, there are no particular limitations on the pixel arrangement, and various arrangements can be applied. Examples of pixel arrangements include stripe arrangement (see Figure 29B), S-stripe arrangement (see Figure 29C), delta arrangement (see Figure 29D), zigzag arrangement (see Figure 29E), and pentile arrangement (see Figure 29F). Other examples include mosaic arrangement, diamond arrangement, and Bayer arrangement.

[0379] Furthermore, in Figures 29B to 29F, the top surface shape of each sub-pixel (pixel 453R, pixel 453G, and pixel 453B) can be, for example, a triangle, a quadrilateral (including rectangles and squares), a pentagon, or other polygons, a polygon with rounded corners, an ellipse, or a circle. Here, the top surface shape of each sub-pixel corresponds to the top surface shape of the display area of ​​the display element that each sub-pixel possesses. The top surface shape and size of each sub-pixel can be determined independently. Note that the arrangement of pixels 453R, 453G, and 453B may be changed as appropriate. Also, the display elements and pixel circuits can be arranged in the same way, or in different ways.

[0380] Here, the PenTile arrangement is a special pixel arrangement that artificially increases resolution. Therefore, in a display device, for example, a stripe arrangement can be adopted. In one aspect of the present invention, the occupied area of ​​the pixel circuit can be reduced by using vertical transistors, such as the transistor 200C or transistor 200D described above, for some or all of the transistors constituting the pixel circuit. Therefore, the pixel arrangement can be changed from a PenTile arrangement to, for example, a stripe arrangement, without reducing the resolution of the display device. Furthermore, it is also possible to reduce the occupied area of ​​the pixel circuit by stacking the transistors shown in the above embodiment.

[0381] [Light-emitting element] Examples of light-emitting elements include self-emissive light-emitting elements such as LEDs, OLEDs, and semiconductor lasers. For example, mini-LEDs or micro-LEDs can be used as LEDs.

[0382] Examples of light-emitting materials for light-emitting devices include fluorescent materials, phosphorescent materials, thermally activated delayed fluorescence (TADF) materials, and inorganic compounds (such as quantum dot materials).

[0383] The light-emitting element can emit light in the following colors: infrared, red, green, blue, cyan, magenta, yellow, or white. Furthermore, the color purity can be improved by adding a microcavity structure to the light-emitting element.

[0384] Of the pair of electrodes or terminals that a light-emitting element has, one functions as the anode (also called the positive electrode) and the other functions as the cathode (also called the negative electrode).

[0385] In this embodiment, the case in which an organic EL element is used as the light-emitting element will be described as an example. Therefore, the display device 400 according to one aspect of the present invention is a display device using an organic EL element.

[0386] Furthermore, the display device 400 according to one aspect of the present invention is suitable for any of the following types: top emission type, which emits light in the direction opposite to the substrate on which the light-emitting element is formed; bottom emission type, which emits light toward the substrate on which the light-emitting element is formed; and dual emission type, which emits light on both sides.

[0387] For example, by using vertical transistors such as transistor 200C or transistor 200D described above, the occupied area of ​​the pixel circuit can be reduced, thereby increasing the aperture ratio of pixels, especially in bottom-emission and dual-emission display devices. For example, display devices with an aperture ratio of 50% or more, 55% or more, or 60% or more can be realized. Furthermore, by stacking the transistors shown in the above embodiment, it is also possible to reduce the occupied area of ​​the pixel circuit and increase the aperture ratio of pixels.

[0388] In this specification, the aperture ratio refers to the ratio of the area of ​​the light-emitting region to the area of ​​the pixel.

[0389] <Example of light-emitting element configuration> A light-emitting element 61 that can be used in a display device according to one aspect of the present invention will be described below.

[0390] As shown in Figure 30A, the light-emitting element 61 includes an EL layer 172 between the conductive layer 171 and the 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).

[0391] The configuration comprising a layer 4420 provided between the electrodes of the conductive layer 171 and the conductive layer 173, a light-emitting layer 4411, and a layer 4430 can function as a single light-emitting unit, and in this specification, the configuration shown in Figure 30A is referred to as a single structure.

[0392] Furthermore, Figure 30B shows a modified example of the EL layer 172 provided in the light-emitting element 61 shown in Figure 30A. Specifically, the light-emitting element 61 shown in Figure 30B 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, when conductive layer 171 is used as the cathode and conductive layer 173 is used 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. By using such a layer structure, it is possible to efficiently inject carriers into the light-emitting layer 4411 and increase the efficiency of carrier recombination within the light-emitting layer 4411.

[0393] As shown in Figure 30C, 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.

[0394] Furthermore, as shown in Figure 30D, a configuration in which multiple light-emitting units (EL layers 172a, EL layers 172b) are connected in series via an intermediate layer (charge generation layer) 4440 is referred to in this specification as a tandem structure or stacked structure. It should be noted that a tandem structure enables the realization of a light-emitting element capable of high-brightness emission.

[0395] Furthermore, when the light-emitting element 61 is in the tandem structure shown in Figure 30D, it is preferable that the light-emitting colors of the EL layer 172a and the EL layer 172b are the same. For example, it is preferable that the light-emitting colors of both the EL layer 172a and the EL layer 172b are green.

[0396] Furthermore, by using a light-emitting element 61 that emits red light (R), a light-emitting element 61 that emits green light (G), and a light-emitting element 61 that emits blue light (B) as sub-pixels, and configuring these three sub-pixels to form one pixel, full-color display can be achieved. When one pixel contains three types of sub-pixels, R, G, and B, it is preferable to have a tandem structure for each light-emitting element 61. 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 the light-emitting layer 4411 and the light-emitting layer 4412 can be the same. By making the emission colors of the EL layers 172a and 172b the same, the current density per unit luminous intensity can be reduced. Therefore, the reliability of the light-emitting element 61 can be improved.

[0397] The light-emitting color of the light-emitting element can be red, green, blue, cyan, magenta, yellow, or white, depending on the material constituting the EL layer 172. Furthermore, the color purity can be further enhanced by adding a microcavity structure to the light-emitting element.

[0398] The light-emitting layer can contain two or more light-emitting materials that emit light in colors such as R (red), G (green), B (blue), Y (yellow), and O (orange). For example, a light-emitting element 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, one should select two light-emitting materials whose emission colors are complementary, or select two or more light-emitting materials whose combined emission results in white light. For example, when obtaining white light emission using two light-emitting layers, a light-emitting element that emits white light as a whole can be obtained by ensuring that the emission colors of the two light-emitting layers are complementary. Also, when obtaining white light emission using three or more light-emitting layers, a light-emitting element that emits white light as a whole can be obtained by combining the emission colors of the three or more light-emitting layers.

[0399] The light-emitting layer preferably contains two or more light-emitting materials that emit light in colors 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. Furthermore, a material that emits near-infrared light can also be used as the light-emitting material.

[0400] Examples of light-emitting materials include fluorescent materials, phosphorescent materials, and thermally activated delayed fluorescence (TADF) materials. The light-emitting material in an EL element can be an organic compound or an inorganic compound (such as a quantum dot material).

[0401] <Method for forming a light-emitting element> Below, an example of a method for forming a light-emitting element 61 will be described.

[0402] Figure 31A shows a schematic top view of the light-emitting element 61. The light-emitting element 61 has multiple red light-emitting elements 61R, multiple green light-emitting elements 61G, and multiple blue light-emitting elements 61B. In Figure 31A, the labels R, G, and B are added within the light-emitting area of ​​each light-emitting element for easy distinction. Also, although Figure 31A illustrates a configuration with three light-emitting colors, red (R), green (G), and blue (B), it is not limited to this. For example, it is possible to have a configuration with four or more colors.

[0403] The light-emitting elements 61R, 61G, and 61B are each arranged in a matrix. Figure 31A shows a so-called stripe arrangement in which light-emitting elements of the same color are arranged in one direction, but the arrangement method of the light-emitting elements is not limited to this.

[0404] It is preferable to use organic EL devices such as OLEDs or QOLEDs (Quantum-dot Organic Light Emitting Diodes) as the light-emitting elements 61R, 61G, and 61B. Examples of light-emitting materials for EL elements include fluorescent materials, phosphorescent materials, and thermally activated delayed fluorescence (TADF) materials. Not only organic compounds but also inorganic compounds (such as quantum dot materials) can be used as light-emitting materials for EL elements.

[0405] Figure 31B is a schematic cross-sectional view corresponding to the dashed line A1-A2 in Figure 31A. Figure 31B shows cross-sections of the light-emitting element 61R, light-emitting element 61G, and light-emitting element 61B. The light-emitting elements 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.

[0406] The light-emitting element 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 having a peak in at least the red wavelength range. The EL layer 172G of the light-emitting element 61G has a luminescent organic compound that emits light having a peak in at least the green wavelength range. The EL layer 172B of the light-emitting element 61B has a luminescent organic compound that emits light having a peak in at least the blue wavelength range.

[0407] Each of the EL layers 172R, 172G, and 172B may also have one or more of the following in addition to the layer containing the light-emitting material (light-emitting layer): an electron injection layer, an electron transport layer, a hole injection layer, and a hole transport layer.

[0408] A conductive layer 171, which functions as a pixel electrode, is provided for each light-emitting element. A conductive layer 173, which functions as a common electrode, is provided as a continuous layer common to each light-emitting element. 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.

[0409] For example, if the light-emitting element 61R is of the top-emission type, the light 175R emitted from the light-emitting element 61R is emitted towards the conductive layer 173. If the light-emitting element 61G is of the top-emission type, the light 175G emitted from the light-emitting element 61G is emitted towards the conductive layer 173. If the light-emitting element 61B is of the top-emission type, the light 175B emitted from the light-emitting element 61B is emitted towards the conductive layer 173.

[0410] An insulator 372 is provided to cover an end portion of a conductive layer 171 that functions as a pixel electrode. The end portion of the insulator 372 is preferably in a tapered shape. The same material as that used for the insulating layer 363 can be used for the insulator 372.

[0411] The insulator 372 is provided to prevent adjacent light-emitting elements 61 from being accidentally short-circuited electrically and emitting light erroneously. Further, when a metal mask is used for forming the EL layer 172, it also has a function of preventing the metal mask from contacting the conductive layer 171.

[0412] The EL layer 172R, the EL layer 172G, and the EL layer 172B each have a region in contact with the upper surface of a conductive layer 171 that functions as a pixel electrode and a region in contact with the surface of the insulator 372. Further, the end portions of the EL layer 172R, the EL layer 172G, and the EL layer 172B are located on the insulator 372.

[0413] As shown in FIG. 31B, a gap is provided between two EL layers between light-emitting elements having different emission colors. Thus, it is preferable that the EL layer 172R, the EL layer 172G, and the EL layer 172B are provided so as not to contact each other. Thereby, it is possible to suitably prevent current from flowing through two adjacent EL layers and causing unintended light emission (also referred to as crosstalk). Therefore, the contrast can be enhanced and a display device with high display quality can be realized.

[0414] The EL layer 172R, the EL layer 172G, and the EL layer 172B can be separately formed by a vacuum evaporation method using a shadow mask such as a metal mask or the like. Alternatively, they can also be separately formed by a photolithography method. By using the photolithography method, a display device with high definition, which is difficult to achieve when using a metal mask, can be realized.

[0415] In addition, in this specification and the like, a device manufactured using a metal mask or an FMM (fine metal mask, high-precision metal mask) may be referred to as a device having an MM (metal mask) structure. Also, in this specification and the like, a device manufactured without using a metal mask or an FMM may be referred to as a device having an MML (metal maskless) structure. Since the display device having an MML structure is manufactured without using a metal mask, it has a higher degree of design freedom in pixel arrangement, pixel shape, etc. than the display device having an MM structure.

[0416] Also, a protective layer 371 is provided to cover the light-emitting element 61R, the light-emitting element 61G, and the light-emitting element 61B on the conductive layer 173 that functions as a common electrode. The protective layer 371 has a function of preventing impurities such as water from diffusing into each light-emitting element from above.

[0417] As the protective layer 371, for example, it can have a single-layer structure or a laminated structure including at least an inorganic insulating film. Examples of the inorganic insulating film include oxide films or nitride films such as a silicon oxide film, a silicon oxynitride film, a silicon nitride oxide film, a silicon nitride film, an aluminum oxide film, an aluminum oxynitride film, and a hafnium oxide film. Alternatively, a semiconductor material such as indium gallium oxide or indium gallium zinc oxide (IGZO) can also be used as the protective layer 371. Note that the protective layer 371 can be formed using an ALD (atomic layer deposition) method, a CVD (chemical vapor deposition) method, or a sputtering method. Although the configuration including an inorganic insulating film is exemplified as the protective layer 371, it is not limited thereto. For example, a laminated structure of an inorganic insulating film and an organic insulating film can also be used as the protective layer 371.

[0418] Note that the structure shown in FIG. 31B may be referred to as an SBS structure, which will be described later.

[0419] Figure 31C shows a different example from the above. Specifically, Figure 31C has a light-emitting element 61W that emits white light. The light-emitting element 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.

[0420] The EL layer 172W can be configured, for example, by stacking two or more light-emitting layers selected so that their respective light-emitting colors are complementary. It is also possible to use a stacked EL layer with a charge-generating layer sandwiched between the light-emitting layers.

[0421] Figure 31C shows three light-emitting elements 61W arranged side by side. A colored layer 264R is provided on the top of the left light-emitting element 61W. The colored layer 264R functions as a bandpass filter that transmits red light. Similarly, a colored layer 264G that transmits green light is provided on the top of the center light-emitting element 61W, and a colored layer 264B that transmits blue light is provided on the top of the right light-emitting element 61W. As a result, the display device can display a color image.

[0422] Here, the EL layer 172W and the conductive layer 173, which functions as a common electrode, are separated between two adjacent light-emitting elements 61W. This prevents current from flowing through the EL layer 172W between two adjacent light-emitting elements 61W, thus preventing unintended light emission. In particular, when a stacked EL layer with a charge generation layer between 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.

[0423] It is preferable to separate the EL layer 172W and the conductive layer 173, which functions as a common electrode, by photolithography. This allows the spacing between light-emitting elements to be narrowed, and thus a display device with a higher aperture ratio can be realized compared to cases where a shadow mask such as a metal mask is used.

[0424] In the case of a bottom-emission type light-emitting element, a colored layer can be provided between the conductive layer 171, which functions as a pixel electrode, and the insulating layer 363.

[0425] Figure 31D shows a different example from the above. Specifically, Figure 31D shows a configuration in which the insulator 372 is not provided between the light-emitting element 61R, light-emitting element 61G, and light-emitting element 61B. This configuration makes it possible to create a display device with a high aperture ratio. In addition, by not providing the insulator 372, the unevenness of the light-emitting element 61 is reduced, so the viewing angle of the display device is improved. Specifically, the viewing angle can be made 150 degrees or more and less than 180 degrees, preferably 160 degrees or more and less than 180 degrees.

[0426] Furthermore, the protective layer 371 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, since the leakage current between adjacent light-emitting elements 61 is reduced, the saturation and contrast ratio are improved, and power consumption is reduced.

[0427] Furthermore, in the configuration shown in Figure 31D, the planar shapes of the conductive layer 171, the EL layer 172R, and the conductive layer 173 are roughly coincide. 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 171 using the conductive layer 173 as a mask. Although the EL layer 172R has been described here, the same configuration can be used for the EL layer 172G and the EL layer 172B.

[0428] Furthermore, in Figure 31D, a protective layer 373 is provided on top of the protective layer 371. For example, by forming the protective layer 371 using an apparatus capable of forming a highly covering film (typically an ALD apparatus, etc.) and forming the protective layer 373 using an apparatus capable of forming a film with lower covering properties than the protective layer 371 (typically a sputtering apparatus, etc.), a region 374 can be provided between the protective layer 371 and the protective layer 373. In other words, the region 374 is located between the EL layer 172R and the EL layer 172G, and between the EL layer 172G and the EL layer 172B.

[0429] Region 374 may contain 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 374 may also contain gases used during the deposition of the protective layer 373. For example, when the protective layer 373 is deposited by sputtering, region 374 may contain one or more of the above-mentioned Group 18 elements. If region 374 contains gases, the gases can be identified by gas chromatography or the like. Alternatively, when the protective layer 373 is deposited by sputtering, the protective layer 373 may also contain gases used during sputtering. In this case, when the protective layer 373 is analyzed by energy-dispersive X-ray spectroscopy (EDX analysis), elements such as argon may be detected.

[0430] Furthermore, if the refractive index of region 374 is lower than that of the protective layer 371, the light emitted from the EL layer 172R, EL layer 172G, or EL layer 172B will be reflected at the interface between the protective layer 371 and region 374. This can suppress the incidence of light emitted from the 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.

[0431] In the configuration shown in Figure 31D, the region between the light-emitting element 61R and the light-emitting element 61G, or the region between the light-emitting element 61G and the light-emitting element 61B (hereinafter simply referred to as the distance between light-emitting elements) can be narrowed. Specifically, the distance between light-emitting elements 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 the EL layer 172R and the side surface of the EL layer 172G, or the distance between the side surface of the EL layer 172G and the side surface of the 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.

[0432] Furthermore, for example, if region 374 contains a gas, it is possible to isolate the light-emitting elements while suppressing color mixing or crosstalk of light from each light-emitting element.

[0433] Furthermore, region 374 may be an empty space or 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. Photoresist can also be used as a filler. The photoresist used as a filler may be a positive-type photoresist or a negative-type photoresist.

[0434] Figure 32A shows a different example from the above. Specifically, the configuration shown in Figure 32A differs from the configuration shown in Figure 31D in the configuration of the insulating layer 363. When the light-emitting elements 61R, 61G, and 61B are processed, a portion of the upper surface of the insulating layer 363 is scraped away, creating a recess. A protective layer 371 is formed in this recess. In other words, in a cross-sectional view, the lower surface of the protective layer 371 is located lower than the lower surface of the conductive layer 171. Having this region effectively suppresses impurities (typically water, etc.) that could enter the light-emitting elements 61R, 61G, and 61B from below. The recess can be formed when impurities (also called residues) that may adhere to the sides of each light-emitting element during processing are removed by wet etching or the like. After removing the above-mentioned residues, covering the sides of each light-emitting element with the protective layer 371 makes it possible to create a highly reliable display device.

[0435] Figure 32B shows a different example from the above. Specifically, the configuration shown in Figure 32B includes an insulator 376 and a microlens array 377 in addition to the configuration shown in Figure 32A. The insulator 376 functions as an adhesive layer. When the refractive index of the insulator 376 is lower than that of the microlens array 377, the microlens array 377 can concentrate the light emitted from the light-emitting elements 61R, 61G, and 61B. This can improve the light extraction efficiency of the display device. This is particularly advantageous when a user views the display surface of the display device from the front, as it allows for the viewing of a bright image. Various types of curing adhesives can be used as the insulator 376, 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 can also be used. Adhesive sheets can also be used.

[0436] Figure 32C shows a different example from the above. Specifically, the configuration shown in Figure 32C has three light-emitting elements 61W instead of the light-emitting elements 61R, 61G, and 61B in the configuration shown in Figure 32A. In addition, there is an insulator 376 above the three light-emitting elements 61W, and above the insulator 376 there are colored layers 264R, 264G, and 264B. Specifically, a colored layer 264R that transmits red light is provided in a position overlapping with the left light-emitting element 61W, a colored layer 264G that transmits green light is provided in a position overlapping with the central light-emitting element 61W, and a colored layer 264B that transmits blue light is provided in a position overlapping with the right light-emitting element 61W. As a result, the semiconductor device can display a color image. The configuration shown in Figure 32C is also a modified example of the configuration shown in Figure 31C.

[0437] Figure 32D shows a different example from the above. Specifically, in the configuration shown in Figure 32D, the protective layer 371 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 element. In addition, in the configuration shown in Figure 32D, it is preferable that the region 374 is filled with a filler material.

[0438] By adding a microcavity structure to the light-emitting element 61, it is possible to improve the color purity of the emitted color. To add a microcavity structure to the light-emitting element 61, it is preferable to configure it so that 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) is m times half the wavelength λ (where m is an integer of 1 or more). The distance d can be calculated using formula (2).

[0439] d=m×λ / (2×n)... (2)

[0440] From equation (2), the distance d of the light-emitting element 61 in the 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.

[0441] More precisely, distance d is the distance from the reflective region of the conductive layer 171, which functions as a reflective electrode, to the reflective region of the conductive layer 173, which functions as an electrode (semitransmissive / semireflective electrode) that has both transmittance and reflectivity to emitted light. For example, if the conductive layer 171 is a laminate of silver and a transparent conductive film called ITO (Indium Tin Oxide), and the ITO is on the EL layer 172 side, the distance d according to the emission color can be set by adjusting the thickness of the ITO. That is, even if the thicknesses of EL layers 172R, 172G, and 172B are the same, a distance d suitable for the emission color can be obtained by changing the thickness of the ITO.

[0442] However, it can be difficult to precisely determine the position of the reflective regions in the conductive layer 171 and the conductive layer 173. In this case, it is assumed that the effect of the microcavity can be sufficiently obtained by assuming that any position in the conductive layer 171 and the conductive layer 173 is a reflective region.

[0443] The light-emitting element 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 element 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 element 61.

[0444] Furthermore, 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. The transmittance of light in the conductive layer 173 is preferably 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.

[0445] Figure 33A shows a different example from the above. Specifically, in the configuration shown in Figure 33A, the EL layer 172 extends beyond the edge of the conductive layer 171 in each of the light-emitting elements 61R, 61G, and 61B. For example, in light-emitting element 61R, the EL layer 172R extends beyond the edge of the conductive layer 171. Also, in light-emitting element 61G, the EL layer 172G extends beyond the edge of the conductive layer 171. In light-emitting element 61B, the EL layer 172B extends beyond the edge of the conductive layer 171.

[0446] Furthermore, in each of the light-emitting elements 61R, 61G, and 61B, the EL layer 172 and the protective layer 371 have overlapping regions via the insulating layer 270. In addition, an insulator 378 is provided on the protective layer 371 in the region between adjacent light-emitting elements 61.

[0447] Examples of the insulator 378 include epoxy resin, acrylic resin, silicone resin, phenolic resin, polyimide resin, imide resin, PVC (polyvinyl chloride) resin, PVB (polyvinyl butyral) resin, EVA (ethylene vinyl acetate) resin, and the like. Also, a photoresist can be used as the insulator 378. The photoresist used as the insulator 378 may be a positive-type photoresist or a negative-type photoresist.

[0448] Further, a common layer 174 is provided over the light-emitting element 61R, the light-emitting element 61G, the light-emitting element 61B, and the insulator 378, and a conductive layer 173 is provided over the common layer 174. The common layer 174 has regions that contact the EL layer 172R, the EL layer 172G, and the EL layer 172B. The common layer 174 is shared by the light-emitting element 61R, the light-emitting element 61G, and the light-emitting element 61B.

[0449] As the common layer 174, one or more of a hole injection layer, a hole transport layer, a hole blocking layer, an electron blocking layer, an electron transport layer, and an electron injection layer can be applied. For example, the common layer 174 may be a carrier injection layer (a hole injection layer or an electron injection layer). Also, the common layer 174 can be said to be a part of the EL layer 172. Note that the common layer 174 may be provided as necessary. When the common layer 174 is provided, a layer having the same function as the common layer 174 among the layers included in the EL layer 172 does not have to be provided.

[0450] Further, a protective layer 373 is provided over the conductive layer 173, and an insulator 376 is provided over the protective layer 373.

[0451] Figure 33B also shows a different example from the above. Specifically, the configuration shown in Figure 33B has three light-emitting elements 61W instead of the light-emitting elements 61R, 61G, and 61B in the configuration shown in Figure 33A. In addition, there is an insulator 376 above the three light-emitting elements 61W, and above the insulator 376 there are colored layers 264R, 264G, and 264B. Specifically, a colored layer 264R that transmits red light is provided in a position overlapping with the left light-emitting element 61W, a colored layer 264G that transmits green light is provided in a position overlapping with the central light-emitting element 61W, and a colored layer 264B that transmits blue light is provided in a position overlapping with the right light-emitting element 61W. As a result, the semiconductor device can display a color image. The configuration shown in Figure 33B is also a modified version of the configuration shown in Figure 32C.

[0452] Furthermore, as shown in Figure 33C, it is possible to provide a light-emitting element 61R, a light-emitting element 61G, and a light-receiving element 71 on the insulating layer 363. The light-receiving element 71 shown in Figure 33C can be realized by replacing the EL layer 172 of the light-emitting element 61 with an active layer 182 (also called the "light-receiving layer") that functions as a photoelectric conversion layer. The active layer 182 has the characteristic that its resistance value changes depending on the wavelength and intensity of the incident light. The active layer 182 can be formed from an organic compound, similar to the EL layer 172. It is also possible to use an inorganic material such as silicon as the active layer 182.

[0453] The light-receiving element 71 has the function of detecting light Lin incident from outside the display device via the protective layer 373, the conductive layer 173, and the common layer 174. It is preferable to provide a colored layer that transmits light in an arbitrary wavelength range on the incident side of the light Lin, superimposed on the light-receiving element 71.

[0454] <Materials applicable to light-emitting elements> This section describes materials applicable to light-emitting elements.

[0455] The hole injection layer is a layer that injects holes from the anode into the hole transport layer, and is a layer containing a material with high hole injection capabilities. Examples of materials with high hole injection capabilities include aromatic amine compounds and composite materials containing hole transport materials and acceptor materials (electron-accepting materials).

[0456] The hole transport layer is a layer that transports holes injected from the anode by the hole injection layer to the light-emitting layer. The hole transport layer is a layer containing a hole-transporting material. The hole-transporting material is 1 × 10⁻¹⁶ −６ cm ２ Materials having a hole mobility of 1 / Vs or higher are preferred. Other materials can also be used as long as they have higher hole transport capabilities than electron transport. Preferred hole transport materials include π-electron-rich heteroaromatic compounds (e.g., carbazole derivatives, thiophene derivatives, furan derivatives, etc.) and aromatic amines (compounds having an aromatic amine skeleton), which are materials with high hole transport capabilities.

[0457] The electron transport layer is a layer that transports electrons injected from the cathode by the electron injection layer to the light-emitting layer. The electron transport layer is a layer containing an electron-transporting material. The electron-transporting material is 1 × 10⁻¹⁶ −６ cm ２ Materials having an electron mobility of 1 / Vs or higher are preferred. However, other materials can also be used as long as they have higher electron transport capabilities than holes. Examples of electron-transporting materials include metal complexes having a quinoline skeleton, metal complexes having a benzoquinoline skeleton, metal complexes having an oxazole skeleton, metal complexes having a thiazole skeleton, as well as oxadiazole derivatives, triazole derivatives, imidazole derivatives, oxazole derivatives, thiazole derivatives, phenanthroline derivatives, quinoline derivatives having a quinoline ligand, benzoquinoline derivatives, quinoxaline derivatives, dibenzoquinoxaline derivatives, pyridine derivatives, bipyridine derivatives, pyrimidine derivatives, and other π-electron-deficient heteroaromatic compounds containing nitrogen-containing heteroaromatic compounds, among other materials with high electron transport capabilities.

[0458] The electron injection layer is a layer that injects electrons from the cathode to the electron transport layer, and is a layer containing a material with high electron injection potential. Alkali metals, alkaline earth metals, or compounds thereof can be used as materials with high electron injection potential. Composite materials containing both electron transport materials and donor materials (electron-donating materials) can also be used as materials with high electron injection potential.

[0459] Examples of electron injection layers include lithium, cesium, ytterbium, lithium fluoride (LiF), cesium fluoride (CsF), and calcium fluoride (CaF). ｘ (where x is any number), 8-(quinolinolato)lithium (abbreviation: Liq), 2-(2-pyridyl)phenolatritium (abbreviation: LiPP), 2-(2-pyridyl)-3-pyridinolatritium (abbreviation: LiPPy), 4-phenyl-2-(2-pyridyl)phenolatritium (abbreviation: LiPPP), lithium oxide (LiO ｘ Alkali metals such as cesium carbonate, alkaline earth metals, or compounds thereof can be used. Furthermore, a multilayer structure of two or more layers can be used as the electron injection layer. For example, this multilayer structure can consist of lithium fluoride as the first layer and ytterbium as the second layer.

[0460] Alternatively, an electron-transporting material can be used as the electron injection layer. For example, a compound having a lone pair of electrons and an electron-deficient heteroaromatic ring can be used as the electron-transporting material. Specifically, a compound having at least one of a pyridine ring, a diazine ring (pyrimidine ring, pyrazine ring, pyridazine ring), or a triazine ring can be used.

[0461] Furthermore, it is preferable that the Lowest Unoccupied Molecular Orbital (LUMO) level of an organic compound containing a lone pair of electrons is between -3.6 eV and -2.3 eV. In addition, the Highest Occupied Molecular Orbital (HOMO) level and LUMO level of an organic compound can generally be estimated by methods such as cyclic voltammetry (CV), photoelectron spectroscopy, optical absorption spectroscopy, and inverse photoelectron spectroscopy.

[0462] For example, 4,7-diphenyl-1,10-phenanthroline (abbreviated as BPhen), 2,9-di(naphthalene-2-yl)-4,7-diphenyl-1,10-phenanthroline (abbreviated as NBPhen), 2,2'-(1,3-phenylene)bis(9-phenyl-1,10-phenanthroline) (abbreviated as mPPhen2P), diquinoxalino[2,3-a:2',3'-c]phenazine (abbreviated as HATNA), 2,4,6-tris[3'-(pyridine-3-yl)biphenyl-3-yl]-1,3,5-triazine (abbreviated as TmPPPyTz), etc., can be used in organic compounds containing lone pairs of electrons. Compared to BPhen, NBPhen has a higher glass transition temperature (Tg) and superior heat resistance.

[0463] <Example of circuit configuration of display device> Figures 34A and 34B are block diagrams illustrating an example of the configuration of a display device 460 (display device 460A and display device 460B) that can be used in a display device 400 according to one aspect of the present invention.

[0464] As shown in Figure 34A, the display device 460A includes a display unit 462, a first drive circuit unit 463, and a second drive circuit unit 464. The display unit 462 has, for example, a plurality of pixels 461 arranged in a matrix of m rows and n columns (where m and n are integers of 2 or more).

[0465] Furthermore, when at least a portion of the display device 460A is used in the display device 400 described above, the pixel 461 corresponds to the pixel 453, the display unit 462 corresponds to the display unit 452, the first drive circuit unit 463 corresponds to the circuit unit 454a, and the second drive circuit unit 464 corresponds to the circuit unit 454b. Therefore, the semiconductor device 10 according to one aspect of the present invention can be used as the pixel 461. Furthermore, the first drive circuit unit 463 and the second drive circuit unit 464 may each include at least a portion of the IC 456.

[0466] In Figure 34A, pixel 461 located in the first row and first column is shown as pixel 461[1,1], pixel 461 located in the first row and nth column is shown as pixel 461[1,n], pixel 461 located in the m row and first column is shown as pixel 461[m,1], and pixel 461 located in the m row and nth column is shown as pixel 461[m,n]. Note that pixel 461 located in the u row and v column (where u is an integer between 1 and m, and v is an integer between 1 and n) may be shown as pixel 461[u,v].

[0467] Furthermore, the display device 460 has m wirings 465, each arranged in parallel or approximately parallel, and whose potential is controlled by a circuit included in the first drive circuit unit 463. The potential of one wiring 465 is supplied to n pixels 461 arranged in the row direction. Depending on the configuration of the pixels 461, it is also possible to have a configuration in which multiple wirings are included per wiring 465. When a semiconductor device 10A or semiconductor device 10B according to one aspect of the present invention is used as the pixels 461, three wirings are used per wiring 465. For example, the three wirings function as wiring AN, wiring GL, and wiring PL.

[0468] Furthermore, the display device 460 has n wirings 466, each arranged in parallel or approximately parallel, and whose potential is controlled by a circuit included in the second drive circuit section 464. The potential of one wiring 466 is supplied to m pixels 461 arranged in the column direction. Depending on the configuration of the pixels 461, it is also possible to have a configuration in which multiple wirings are included per wiring 466. When a semiconductor device 10A or semiconductor device 10B according to one aspect of the present invention is used as the pixels 461, the wiring 466 can be used as wiring SL.

[0469] Pixel 461 has the function of causing a light-emitting element to emit light at a light-emitting intensity corresponding to the video signal by writing a video signal to a pixel circuit selected by the potential of the wiring 465 via the wiring 466.

[0470] The circuit included in the first drive circuit section 463 functions, for example, as a scan line drive circuit (sometimes called a gate line drive circuit, gate driver, scan driver, or low driver).

[0471] The circuit included in the second drive circuit section 464 functions, for example, as a signal line drive circuit (sometimes called a source line drive circuit, source driver, data driver, or column driver). It can also have the function of converting the data of an image displayed on the display device 460 into a video signal to be supplied to each pixel (digital-to-analog conversion).

[0472] Furthermore, in the pixel 461, for example, the current flowing through the light-emitting element can be output to a monitor line (not shown). The current output to the monitor line can be converted to an analog voltage (current-voltage conversion) or a digital signal (analog-digital conversion) in the second drive circuit 464, for example, and output to the outside of the display device 460. Using this analog voltage or digital signal, for example, correction of the video signal (also called external correction) can be performed outside the display device.

[0473] In one aspect of the present invention, various configurations can be used as variations of the display device 460. For example, as shown in Figure 34B, two first drive circuit units 463 (first drive circuit unit 463L and first drive circuit unit 463R) can be arranged facing each other with the display unit 462 in between.

[0474] The display device 460B shown in Figure 34B has the function of controlling the potential of m wires 465 by both the circuit included in the first drive circuit unit 463L and the circuit included in the first drive circuit unit 463R. In other words, it has the function of controlling the potential of one wire 465 by both the first drive circuit unit 463L and the first drive circuit unit 463R. With this configuration, the potential supply capacity to one wire 465 can be doubled. For example, the effective load on the wiring (parasitic capacitance and parasitic resistance) can be halved. Therefore, it is possible to increase the speed, resolution, and bezel of the display device.

[0475] Although not shown in the diagram, it is also possible to configure the system such that, for example, two second drive circuit units 464 are arranged facing each other with the display unit 462 in between.

[0476] Furthermore, in one aspect of the present invention, in addition to the various configurations of the display device 460 described above, a sensor unit may be provided so as to overlap with the display unit 462 when viewed from above. This sensor unit may have functions such as a touch sensor, a near-touch sensor, or a fingerprint sensor. These sensors may be capacitive or optical, for example.

[0477] Furthermore, in the display device 460 equipped with a sensor unit, the first drive circuit unit 463 (or the first drive circuit unit 463L and the first drive circuit unit 463R) may include, for example, a circuit having the function of driving the sensor unit. Also, the second drive circuit unit 464 may include, for example, a circuit having the function of outputting the signal detected by the sensor unit to the outside of the display device.

[0478] [Peripheral Drive Circuit] Next, we will describe the configuration examples of each element circuit that can be used in the peripheral drive circuit of the display device 460.

[0479] In this specification, the circuits included in the first drive circuit section 463 and the circuits included in the second drive circuit section 464 of the display device 460 may be collectively referred to as "peripheral drive circuits."

[0480] Peripheral drive circuits can be constructed using various elemental circuits. Examples of such elemental circuits include shift register circuits, flip-flop circuits, latch circuits, buffer circuits, inverter circuits, and level shifter circuits. Other examples include multiplexer circuits, demultiplexer circuits, source follower circuits, common-source amplifier circuits, sample-and-hold circuits, and switch circuits (e.g., transmission gates and analog switches). Other examples include current-voltage conversion circuits, analog-to-digital conversion circuits, digital-to-analog conversion circuits, operational amplifier circuits, comparator circuits, pass-transistor logic circuits, encoder circuits, decoder circuits, and gate circuits (e.g., AND circuits, OR circuits, and NOT circuits). Circuits combining these circuits are also possible. These elemental circuits can be constructed using, for example, transistors and capacitive elements.

[0481] Furthermore, in one aspect of the present invention, various transistors can be used as transistors constituting the peripheral drive circuit. For example, the transistor 200 described above can be used as part or all of the transistors constituting the peripheral drive circuit. For example, vertical transistors such as transistor 200C or transistor 200D can be used.

[0482] By using vertical transistors for some or all of the transistors constituting the peripheral drive circuit, the occupied area of ​​components such as buffer circuits included in the first drive circuit section 463 can be reduced. This allows for, for example, a narrower bezel for the display device. Furthermore, the occupied area of ​​components such as demultiplexers and source followers included in the second drive circuit section 464 can be reduced. This allows for higher resolution and higher definition for the display device.

[0483] Furthermore, some or all of the transistors constituting the peripheral drive circuit can be, for example, OS transistors. Alternatively, both OS transistors and Si transistors can be used.

[0484] As mentioned above, OS transistors have the characteristic of having an extremely low off-current. They also have the characteristic that the off-current hardly increases even in high-temperature environments, and the on-current does not easily decrease. Si transistors have a faster operating speed than OS transistors. Furthermore, Si transistors can be used to construct CMOS circuits (for example, complementary circuits, CMOS logic gates, or CMOS logic circuits) by connecting, for example, the gate of an n-type transistor to the gate of a p-type transistor.

[0485] Furthermore, it is possible to construct a CMOS circuit using an OS transistor as the n-type transistor and a Si transistor as the p-type transistor. By using an OS transistor and a Si transistor in combination, a semiconductor device with low power consumption and high operating speed can be realized. Therefore, depending on the specifications of the display device, an OS transistor and a Si transistor can be appropriately used as transistors to constitute the peripheral drive circuit.

[0486] <Example of Cross-Sectional Structure of Display Device> Figure 35 is a cross-sectional view illustrating an example of the cross-sectional structure of a display device according to one embodiment of the present invention.

[0487] In the display device 490 shown in Figure 35, the configurations shown in regions 490a, 490b, and 490c can each be used in the display device 400. For example, the configuration shown in region 490a can be used in the region where pixels 453 are provided. The configuration shown in region 490b can be used in the region where circuit sections 454a and 454b are provided. The configuration shown in region 490c can be used in the region where the FPC 459 is provided.

[0488] The display device 490 has a substrate 351 and a substrate 352. An adhesive layer 342 is also present between the substrates 351 and 352. Substrate 352 faces substrate 351 via the adhesive layer 342. Note that region 490c does not have substrate 352 or adhesive layer 342.

[0489] An insulating layer 382 is provided on the substrate 352 side of substrate 351. Transistors and light-emitting elements are provided on the insulating layer 382.

[0490] Here, as an example, a configuration is shown in which transistors 200A and 200B as shown in the above-described embodiment are provided in region 490a, and transistor 200A as shown in the above-described embodiment is provided in region 490b. In addition, a conductive layer 384 is provided in region 490c. The conductive layer 384 can be formed in the same process as conductive layers 208a and 208b.

[0491] An insulating layer 228 is provided so as to cover transistors 200A and 200B.

[0492] In region 490a, a pixel electrode 311 is provided on the insulating layer 228. The pixel electrode 311 is connected to the conductive layer 208b through openings provided in the insulating layer 228 and the insulating layer 209. In addition, an insulating layer 237 is provided on the insulating layer 228. The insulating layer 237 has a region that covers the end of the pixel electrode 311.

[0493] Furthermore, an EL layer 313 is provided so as to cover the insulating layer 237 and the pixel electrode 311. A common electrode 315 is provided so as to cover the EL layer 313. A protective layer 331 is provided so as to cover the common electrode 315.

[0494] The pixel electrode 311 and the common electrode 315 overlap via the EL layer 313, and the pixel electrode 311 and the EL layer 313 are in contact. The region where the EL layer 313 and the common electrode 315 are in contact functions as a light-emitting element 330. The light-emitting element 330 corresponds to the light-emitting element 61 shown in the above embodiment. The pixel electrode 311 functions as one electrode (or first terminal) of the light-emitting element 330, and the common electrode 315 functions as the other electrode (or second terminal). The EL layer 313 has the function of emitting light with a brightness corresponding to the amount of current flowing between the pixel electrode 311 and the common electrode 315 via the EL layer 313.

[0495] A light-shielding layer 317 is provided on the substrate 351 side of the substrate 352. In region 490a, an opening is provided in the light-shielding layer 317 such that it overlaps with the light-emitting element 330. Therefore, the light emitted by the light-emitting element 330 is emitted to the outside of the display device 490 through the opening provided in the light-shielding layer 317. In Figure 35, this is represented by a dashed arrow and the inscription "Light".

[0496] In region 490c, a conductive layer 386 is provided on a portion of the insulating layer 228. The conductive layer 386 has a region that is in contact with the conductive layer 384 through openings provided in the insulating layer 228 and the insulating layer 209.

[0497] The conductive layer 386 is connected to the FPC 459 via a connecting layer 388. As the connecting layer 388, for example, an anisotropic conductive film (ACF) and an anisotropic conductive paste (ACP) can be used.

[0498] The configuration shown in this embodiment can be used in appropriate combination with the configurations shown in other embodiments.

[0499] (Embodiment 7) In this embodiment, an electronic device according to one aspect of the present invention will be described with reference to the drawings.

[0500] The electronic device shown in this embodiment has a display device (hereinafter also simply referred to as "display device") using a semiconductor device according to one aspect of the present invention as its display unit. This display device is easily made high-definition and high-resolution. Therefore, it can be used in the display units of various electronic devices.

[0501] Examples of electronic devices include those with relatively large screens, such as television sets, desktop or notebook computers, computer monitors, digital signage, and large game machines like pachinko machines, as well as digital cameras, digital video cameras, digital photo frames, mobile phones, portable game consoles, personal digital assistants, and audio playback devices.

[0502] In particular, a display device according to one aspect of the present invention can be used in electronic devices having a relatively small display area because it can increase the resolution. Examples of such electronic devices include wearable devices that can be worn on the wrist, such as wristwatch-type and bracelet-type information terminals, and wearable devices that can be worn on the head, such as head-mounted displays for VR (Virtual Reality), glasses-type devices for AR (Augmented Reality), devices for SR (Substitutional Reality), and devices for MR (Mixed Reality).

[0503] A display device according to one aspect of the present invention can have extremely high resolutions such as HD (1280 x 720 pixels), FHD (1920 x 1080 pixels), WQHD (2560 x 1440 pixels), WQXGA (2560 x 1600 pixels), 4K (3840 x 2160 pixels), or 8K (7680 x 4320 pixels). In particular, it is possible to have a resolution of 4K, 8K or higher. Furthermore, a display device according to one aspect of the present invention can have a pixel density (detail) of 300 ppi or more, 500 ppi or more, or 1000 ppi or more. Alternatively, it is possible to have a detail of 3000 ppi or more or 5000 ppi or more. By using a display device having one or both of these high resolutions and high detail, it is possible to further enhance the sense of presence and depth. Furthermore, there are no particular limitations on the screen ratio (aspect ratio) of the display device according to one aspect of the present invention. For example, a display device according to one aspect of the present invention can support various aspect ratios such as 1:1 (square), 4:3, 16:9, or 16:10.

[0504] The electronic device of this embodiment may have sensors (including functions for detecting, detecting, or measuring force, displacement, position, velocity, acceleration, angular velocity, rotational speed, distance, light, liquid, magnetism, temperature, chemical substances, sound, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, gradient, vibration, odor, or infrared radiation).

[0505] The electronic device of this embodiment can have a variety of functions. For example, it can have a function to display various information (still images, videos, and text images, etc.) on the display unit, a touch panel function, a function to display a calendar, date or time, a function to execute various software (programs), a wireless communication function, and a function to read programs or data recorded on a recording medium.

[0506] Figures 36A to 36D illustrate an example of a wearable device that can be worn on the head. These wearable devices have at least one of the following functions: a function to display AR content, a function to display VR content, a function to display SR content, and a function to display MR content. By having an electronic device that has the function to display at least one of the following content types, such as AR, VR, SR, and MR, it is possible to enhance the user's sense of immersion.

[0507] The electronic device 700A shown in Figure 36A and the electronic device 700B shown in Figure 36B each include a pair of display panels 751, a pair of housings 721, a communication unit (not shown), a pair of mounting units 723, a control unit (not shown), an imaging unit (not shown), a pair of optical members 753, a frame 757, and a pair of nose pads 758.

[0508] A display device according to one embodiment of the present invention can be applied to the display panel 751. Therefore, an electronic device capable of displaying extremely high resolution can be created.

[0509] Electronic devices 700A and 700B can project an image displayed on the display panel 751 onto the display area 756 of the optical element 753. Because the optical element 753 is translucent, the user can see the image displayed on the display area superimposed on the transmitted image visible through the optical element 753. Therefore, electronic devices 700A and 700B are electronic devices capable of AR display.

[0510] Electronic devices 700A and 700B can be equipped with cameras capable of capturing images of the area in front of them as imaging units. Furthermore, electronic devices 700A and 700B can each be equipped with acceleration sensors such as gyro sensors to detect the orientation of the user's head and display an image corresponding to that orientation in the display area 756.

[0511] The communications unit has a wireless communication device, which can supply video signals and other signals. Alternatively, in addition to or instead of the wireless communication device, it may be equipped with a connector to which a cable supplying video signals and power potential can be connected.

[0512] Electronic devices 700A and 700B are equipped with batteries that can be charged wirelessly, wired, or both.

[0513] A touch sensor module can be installed in the housing 721. The touch sensor module has the function of detecting when the outer surface of the housing 721 is touched. The touch sensor module can detect the user's tap or slide operations and perform various processes. For example, a tap operation can be used to pause or resume the video, and a slide operation can be used to fast forward or rewind. Furthermore, by installing a touch sensor module in each of the two housings 721, the range of operations can be expanded.

[0514] Various types of touch sensors can be applied to the touch sensor module. For example, various methods such as capacitive, resistive, infrared, electromagnetic induction, surface acoustic wave, or optical sensors can be used. In particular, it is preferable to apply capacitive or optical sensors to the touch sensor module.

[0515] When using an optical touch sensor, a photoelectric conversion element can be used as the light-receiving element. The active layer of the photoelectric conversion element can be made of either an inorganic semiconductor or an organic semiconductor, or both.

[0516] The electronic device 800A shown in Figure 36C and the electronic device 800B shown in Figure 36D each include a pair of display units 820, a housing 821, a communication unit 822, a pair of mounting units 823, a control unit 824, a pair of imaging units 825, and a pair of lenses 832.

[0517] A display device according to one embodiment of the present invention can be applied to the display unit 820. Therefore, an electronic device capable of displaying extremely high resolution can be created. This allows the user to experience a high level of immersion.

[0518] The display unit 820 is located inside the housing 821 in a position where it can be seen through the lens 832. Furthermore, by displaying different images on a pair of display units 820, a three-dimensional display using parallax can also be performed.

[0519] Electronic devices 800A and 800B can each be described as electronic devices for VR. A user wearing electronic device 800A or electronic device 800B can view the image displayed on the display unit 820 through the lens 832.

[0520] It is preferable that electronic devices 800A and 800B each have a mechanism that allows adjustment of the left and right positions of the lens 832 and the display unit 820 so that they are in the optimal position according to the user's eye position. It is also preferable that they have a mechanism that adjusts the focus by changing the distance between the lens 832 and the display unit 820.

[0521] The attachment portion 823 allows the user to attach the electronic device 800A or 800B to their head. While Figure 36C and other figures illustrate the attachment portion as resembling the temples of eyeglasses, it is not limited to this shape. The attachment portion 823 only needs to be wearable by the user and can be, for example, helmet-shaped or band-shaped.

[0522] The imaging unit 825 has the function of acquiring external information. The data acquired by the imaging unit 825 can be output to the display unit 820. An image sensor can be used in the imaging unit 825. In addition, multiple cameras can be provided to accommodate multiple angles of view, such as telephoto and wide-angle.

[0523] Although an example with an imaging unit 825 is shown here, any distance measuring sensor (hereinafter also referred to as a detection unit) capable of measuring the distance to an object can be provided. In other words, the imaging unit 825 is one form of a detection unit. As the detection unit, for example, an image sensor or a distance image sensor such as LiDAR (Light Detection and Ranging) can be used. By using the image obtained by the camera and the image obtained by the distance image sensor, more information can be acquired, enabling more accurate gesture control.

[0524] The electronic device 800A may have a vibration mechanism that functions as a bone conduction earphone. For example, the vibration mechanism can be applied to one or more of the display unit 820, housing 821, and mounting unit 823. This eliminates the need for separate audio equipment such as headphones, earphones, or speakers, allowing users to enjoy video and audio simply by wearing the electronic device 800A.

[0525] Electronic devices 800A and 800B may each have input terminals. Cables that supply video signals from video output devices, etc., and power for charging batteries provided within the electronic devices can be connected to the input terminals.

[0526] An electronic device according to one aspect of the present invention may have an earphone 750 and a wireless communication function. The earphone 750 has a communication unit (not shown) and has a wireless communication function. The earphone 750 can receive information (e.g., voice data) from an electronic device via wireless communication. For example, the electronic device 700A shown in Figure 36A has a function to transmit information to the earphone 750 via wireless communication. Also, for example, the electronic device 800A shown in Figure 36C has a function to transmit information to the earphone 750 via wireless communication.

[0527] Electronic devices can also have an earphone section. The electronic device 700B shown in Figure 36B has an earphone section 727. For example, the earphone section 727 and the control unit can be connected to each other by a wire. Part of the wiring connecting the earphone section 727 and the control unit can be placed inside the housing 721 or the mounting section 723.

[0528] Similarly, the electronic device 800B shown in Figure 36D has an earphone unit 827. For example, the earphone unit 827 and the control unit 824 can be connected to each other by a wire. Part of the wiring connecting the earphone unit 827 and the control unit 824 can be placed inside the housing 821 or the mounting unit 823. In addition, the earphone unit 827 and the mounting unit 823 can have magnets. This allows the earphone unit 827 to be fixed to the mounting unit 823 by magnetic force, which is preferable as it makes storage easier.

[0529] Furthermore, electronic devices may have an audio output terminal to which earphones or headphones can be connected. Electronic devices may also have either an audio input terminal or an audio input mechanism, or both. For example, a sound-collecting device such as a microphone can be used as the audio input mechanism. By having an audio input mechanism, electronic devices can be given the function of a so-called headset.

[0530] Thus, in one aspect of the present invention, the electronic device is preferably of the glasses type (such as electronic device 700A and electronic device 700B) or the goggle type (such as electronic device 800A and electronic device 800B).

[0531] An electronic device according to one aspect of the present invention can transmit information to earphones by wire or wireless means.

[0532] The electronic device 6500 shown in Figure 37A is a portable information terminal that can be used as a smartphone.

[0533] The electronic device 6500 includes a housing 6501, a display unit 6502, a power button 6503, a button 6504, a speaker 6505, a microphone 6506, a camera 6507, and a light source 6508. The display unit 6502 has a touch panel function.

[0534] A display device according to one aspect of the present invention can be applied to the display unit 6502.

[0535] Figure 37B is a schematic cross-sectional view of the housing 6501 including the end on the microphone 6506 side.

[0536] A light-transmitting protective member 6510 is provided on the display surface side of the housing 6501, and the display panel 6511, optical member 6512, touch sensor panel 6513, printed circuit board 6517, and battery 6518 are arranged in the space enclosed by the housing 6501 and the protective member 6510.

[0537] The protective member 6510 is fixed to the display panel 6511, the optical member 6512, and the touch sensor panel 6513 by an adhesive layer (not shown).

[0538] In the area outside the display unit 6502, a portion of the display panel 6511 is folded back, and the FPC 6515 is connected to this folded portion. IC 6516 is mounted on the FPC 6515. The FPC 6515 is connected to terminals provided on the printed circuit board 6517.

[0539] For example, a display device using a resin substrate can be applied to the display panel 6511. This makes it possible to realize an extremely lightweight electronic device. Also, because the display panel 6511 is extremely thin, it is possible to incorporate a large-capacity battery 6518 while keeping the thickness of the electronic device low. Furthermore, by folding back a part of the display panel 6511 and placing the connection part with the FPC 6515 on the back of the pixel section, it is possible to realize an electronic device with a narrow bezel.

[0540] Figure 37C shows an example of a television device. The television device 7100 has a display unit 7000 incorporated into a housing 7101. Here, a configuration is shown in which the housing 7101 is supported by a stand 7103. In Figure 37C, a display device according to one embodiment of the present invention can be applied to the display unit 7000.

[0541] The television device 7100 shown in Figure 37C 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, allowing the television device 7100 to 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.

[0542] 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 only) or two-way (between sender and receiver, or between receivers, etc.) information communication.

[0543] Figure 37D shows an example of a notebook computer. The notebook computer 7200 has a casing 7211, a keyboard 7212, a pointing device 7213, and an external connection port 7214, etc. A display unit 7000 is incorporated into the casing 7211. In Figure 37D, a display device according to one embodiment of the present invention can be applied to the display unit 7000.

[0544] Figures 37E and 37F show examples of digital signage.

[0545] The digital signage 7300 shown in Figure 37E includes a housing 7301, a display unit 7000, and a speaker 7303. Furthermore, it may include LED lamps, operation keys (including a power switch or operation switch), connection terminals, various sensors, and a microphone.

[0546] Figure 37F shows a digital signage 7400 mounted on a cylindrical column 7401. The digital signage 7400 has a display unit 7000 provided along the curved surface of the column 7401. In Figures 37E and 37F, a display device according to one embodiment of the present invention can be applied to the display unit 7000.

[0547] 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.

[0548] Applying a touch panel to the display unit 7000 is preferable because it not only displays images or videos on the display unit 7000, but also allows users to operate it intuitively. Furthermore, when used for purposes such as providing route information or traffic information, intuitive operation can enhance usability.

[0549] As shown in Figures 37E and 37F, 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.

[0550] 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 an unspecified number of users to participate in and enjoy the game simultaneously.

[0551] The electronic device shown in Figures 38A to 38G includes a housing 9000, a display unit 9001, a speaker 9003, operation keys 9005 (including a power switch or operation switch), connection terminals 9006, a sensor 9007 (including a function to detect, detect or 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), and a microphone 9008, etc.

[0552] In Figures 38A to 38G, a display device according to one embodiment of the present invention can be applied to the display unit 9001.

[0553] The electronic devices shown in Figures 38A to 38G have various functions. For example, they may have functions to display various information (still images, videos, and text images, etc.) on a display unit, a touch panel function, a function to display a calendar, date, or time, a function to control processing by various software (programs), a wireless communication function, and a function to read and process programs or data recorded on a recording medium. However, the functions of electronic devices are not limited to these, and they may have a variety of functions. Electronic devices may have multiple display units. Furthermore, electronic devices may be equipped with a camera or the like, and have functions to capture still images or videos and save them to a recording medium (external or built into the camera), and to display the captured images on a display unit.

[0554] Details of the electronic equipment shown in Figures 38A to 38G will be explained below.

[0555] Figure 38A is a perspective view showing a personal digital information terminal (PDI) 9101. The PDI 9101 can be used, for example, as a smartphone. The PDI 9101 can be equipped with a speaker 9003, connection terminals 9006, sensors 9007, etc. The PDI 9101 can also display text and image information on multiple surfaces. Figure 38A shows an example where three icons 9050 are displayed. Information 9051, indicated by a dashed rectangle, can also be displayed on other surfaces of the display unit 9001. Examples of information 9051 include notifications of incoming emails, SNS messages, or phone calls, as well as the subject, sender name, and date and time of emails or SNS messages. Other examples include the time, battery level, and signal strength. Alternatively, icons 9050 can be displayed in the same location where information 9051 is displayed.

[0556] Figure 38B is a perspective view showing a personal digital assistant (PDA) 9102. The PDA 9102 has the function of displaying information on three or more sides of the display unit 9001. Here, an example is shown in which information 9052, information 9053, and information 9054 are displayed on different sides. For example, a user can check information 9053, which is displayed in a position that can be observed from above the PDA 9102, while the PDA 9102 is stored in the breast pocket of their clothing. For example, a user can check the display without taking the PDA 9102 out of their pocket and decide whether or not to answer a call.

[0557] Figure 38C is a perspective view showing the tablet terminal 9103. The tablet terminal 9103 can run various applications, such as mobile phone calls, email, document viewing and creation, music playback, internet communication, and computer games. The tablet terminal 9103 has a display unit 9001, a camera 9002, a microphone 9008, and a speaker 9003 on the front of the housing 9000, an operation key 9005 as an operation button on the left side of the housing 9000, and a connection terminal 9006 on the bottom of the housing 9000.

[0558] Figure 38D is a perspective view showing a wristwatch-type personal information terminal 9200. The personal information terminal 9200 can be used, for example, as a smartwatch (registered trademark). The display unit 9001 has a curved display surface, allowing it to display information along the curved surface. The personal information terminal 9200 can also make hands-free calls by communicating with, for example, a wireless communication headset. Furthermore, the personal information terminal 9200 can transmit data to and from other information terminals and be charged via a connection terminal 9006. The charging operation may be performed by wireless power supply.

[0559] Figures 38E to 38G are perspective views showing a foldable portable information terminal 9201. Figure 38E is a perspective view of the portable information terminal 9201 in an unfolded state, Figure 38G is a perspective view of it in a folded state, and Figure 38F is a perspective view of the state in between the transition from Figure 38E to Figure 38G. The portable information terminal 9201 offers excellent portability in its folded state and excellent readability of the display due to its seamless, wide display area in its unfolded state. The display unit 9001 of the portable information terminal 9201 is supported by three housings 9000 connected by hinges 9055. For example, the display unit 9001 can be bent with a radius of curvature of 0.1 mm to 150 mm.

[0560] The configuration shown in this embodiment can be used in appropriate combination with the configurations shown in other embodiments.

[0561] 10: Semiconductor device, 10A: Semiconductor device, 10B: Semiconductor device, 10C: Semiconductor device, 10C[u,v]: Semiconductor device, 10C[u+1,v]: Semiconductor device, 10D: Semiconductor device, 55: Linear, 61: Light-emitting element, 61B: Light-emitting element, 61G: Light-emitting element, 61R: Light-emitting element, 61W: Light-emitting element, 71: Photodetector, 171: Conductive layer, 172: EL layer, 172a: EL layer, 172B: EL layer, 172b: EL layer, 172G: EL layer, 172R: EL layer, 172W: EL layer, 173: Conductive layer, 174: Common layer, 175B: Light, 175G: Light, 175R: Light, 182: Active layer

Claims

It comprises first to third transistors, first and second capacitance elements, and a light-emitting element. The first terminal of the first transistor is electrically connected to the first wiring, The second terminal of the first transistor is The first terminal of the first capacitance element, the first terminal of the second capacitance element, and the first terminal of the light-emitting element are electrically connected, The gate of the first transistor is The first terminal of the second transistor and the second terminal of the first capacitive element are electrically connected, The back gate of the first transistor is The first terminal of the third transistor and the second terminal of the second capacitance element are electrically connected, The gate of the third transistor is electrically connected to the second terminal of the third transistor. The back gate of the third transistor is electrically connected to the first wiring. The aforementioned third transistor is a p-type transistor in a semiconductor device. 　 In claim 1, Each of the first and second transistors is a semiconductor device containing an oxide semiconductor in its semiconductor layer. 　 In claim 2, The aforementioned oxide semiconductor is a semiconductor device containing indium. 　 In any one of claims 1 to 3, The third transistor is a semiconductor device containing silicon in its semiconductor layer. 　 In any one of claims 1 to 3, The second terminal of the light-emitting element is electrically connected to the second wiring. A semiconductor device in which the first terminal of the light-emitting element functions as an anode, and the second terminal of the light-emitting element functions as a cathode. 　 In any one of claims 1 to 3, The light-emitting element is an organic EL element, which is a semiconductor device. 　 It comprises a transistor, a first switch, a second switch, a first capacitance element, a second capacitance element, a light-emitting element, and a diode. The first terminal of the transistor is electrically connected to the first wiring. The second terminal of the aforementioned transistor is The first terminal of the first capacitance element, the first terminal of the second capacitance element, and the first terminal of the light-emitting element are electrically connected, The gate of the aforementioned transistor is The first terminal of the first switch and the second terminal of the first capacitive element are electrically connected, The back gate of the aforementioned transistor is The first terminal of the second switch, the second terminal of the second capacitive element, and the anode of the diode are electrically connected. The second terminal of the second switch is electrically connected to the cathode of the diode, which is a semiconductor device. 　 In claim 7, The aforementioned transistor is a semiconductor device containing an oxide semiconductor in its semiconductor layer. 　 In claim 8, The aforementioned oxide semiconductor is a semiconductor device containing indium. 　 In any one of claims 7 to 9, The light-emitting element is an organic EL element, which is a semiconductor device. 　 It comprises first to fourth transistors, first and second capacitance elements, and a light-emitting element. The first terminal of the first transistor is electrically connected to the first wiring, The second terminal of the first transistor is The first terminal of the first capacitance element, the first terminal of the second capacitance element, the first terminal of the fourth transistor, and the first terminal of the light-emitting element are electrically connected, The gate of the first transistor is The first terminal of the second transistor and the second terminal of the first capacitive element are electrically connected, The back gate of the first transistor is The first terminal of the third transistor and the second terminal of the second capacitance element are electrically connected, The gate of the third transistor is electrically connected to the second terminal of the third transistor. The back gate of the third transistor is electrically connected to the first wiring. The gate of the second transistor is electrically connected to the third wiring. The gate of the fourth transistor is electrically connected to the third wiring, The aforementioned third transistor is a p-type transistor in a semiconductor device. 　 In claim 11, Each of the first transistor, the second transistor, and the fourth transistor is a semiconductor device containing an oxide semiconductor in its semiconductor layer. 　 In claim 12, The aforementioned oxide semiconductor is a semiconductor device containing indium. 　 In any one of claims 11 to 13, The third transistor is a semiconductor device containing silicon in its semiconductor layer. 　 In any one of claims 11 to 13, The second terminal of the light-emitting element is electrically connected to the second wiring. A semiconductor device in which the first terminal of the light-emitting element functions as an anode, and the second terminal of the light-emitting element functions as a cathode. 　 In any one of claims 11 to 13, The light-emitting element is an organic EL element, which is a semiconductor device. 　 It comprises a transistor, a first switch, a second switch, a third switch, a first capacitance element, a second capacitance element, a light-emitting element, and a diode. The first terminal of the transistor is electrically connected to the first wiring. The second terminal of the aforementioned transistor is The first terminal of the first capacitance element, the first terminal of the second capacitance element, the first terminal of the third switch, and the first terminal of the light-emitting element are electrically connected, The gate of the aforementioned transistor is The first terminal of the first switch and the second terminal of the first capacitive element are electrically connected, The back gate of the aforementioned transistor is The first terminal of the second switch, the second terminal of the second capacitive element, and the anode of the diode are electrically connected. The second terminal of the second switch is electrically connected to the cathode of the diode, which is a semiconductor device. 　 In claim 17, The function is such that the third switch is turned on when the first switch is turned on, The function of the third switch being in the off state when the first switch is in the off state, Semiconductor device. 　 In claim 17 or claim 18, The aforementioned transistor is a semiconductor device containing an oxide semiconductor in its semiconductor layer. In claim 19, The aforementioned oxide semiconductor is a semiconductor device containing indium. 　 In claim 17 or claim 18, The light-emitting element is an organic EL element, which is a semiconductor device.

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