Semiconductor device

Abstract

A semiconductor device is provided. The semiconductor device includes a first transistor including a first gate, a second gate facing the first gate across a channel formation region of the first transistor, a first source, and a first drain, a second transistor including a third gate, a second source, and a second drain, and a third transistor including a third gate, a second source, and a second drain. The third transistor comprises a fourth grid electrode, a third source electrode and a third drain electrode, one of the first source electrode and the first drain electrode is electrically connected with one of the second source electrode and the second drain electrode, the other one of the first source electrode and the first drain electrode is electrically connected with one of the third source electrode and the third drain electrode, the first grid electrode is electrically connected with the third grid electrode, and the third grid electrode is electrically connected with the third source electrode. And the second gate is electrically connected with the other one of the first source and the first drain.

Description

Technical Field

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

[0002] Note that one aspect of the present invention is not limited to the aforementioned technical fields. The technical field of one aspect of the invention disclosed in this specification relates to an object, method, driving method, or manufacturing method. Additionally, one aspect of the present invention relates to a process, machine, manufacture, or composition of matter. Specifically, as examples of the technical field of one aspect of the present invention disclosed in this specification, examples include semiconductor devices, display devices, light-emitting devices, energy storage devices, optical devices, imaging devices, lighting devices, computing devices, control devices, storage devices, input devices, output devices, input / output devices, signal processing devices, arithmetic processing devices, electronic computers, electronic devices, their driving methods, or their manufacturing methods. Background Technology

[0003] In recent years, display devices have been applied to a variety of uses. For example, as large display devices, examples include home television sets, digital signage, and public information displays (PIDs). As small display devices, examples include portable information terminals such as smartphones and tablets, wearable devices such as VR (Virtual Reality) devices and AR (Augmented Reality) devices. Furthermore, by adding functions beyond display to display devices, their functionality and added value are being enhanced. For example, research is underway on display devices with added touch sensors to provide touch panel functionality.

[0004] In addition, research and development is underway on circuits for driving display devices. Patent Document 1 discloses an example of a driving circuit that can be used in a display device.

[0005] [Preliminary Technology Documents]

[0006] [Patent Literature]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 2008-122939 Summary of the Invention

[0008] The technical problem that the invention aims to solve

[0009] An active matrix display device includes a driving circuit (sometimes called a gate driver) that selects the pixels to write data to and a driving circuit (sometimes called a source driver) that supplies data to the selected pixels.

[0010] To achieve higher brightness, higher resolution, and larger screens in display devices, the operating voltage of pixel circuits and driving circuits is sometimes increased. Consequently, the voltage between the drain and source of the transistors included in the pixel circuits and driving circuits sometimes increases. This raises concerns about transistor characteristic degradation due to the high drain-source voltage. For example, hot carrier degradation is known to occur when hot carriers accelerated by a strong electric field near the drain are injected and accumulate in the gate insulating film, altering the transistor characteristics relative to the gate-source voltage.

[0011] Therefore, transistors used in pixel circuits and driving circuits are required to employ countermeasures to suppress the degradation of transistor characteristics.

[0012] Furthermore, transistors suitable for high-speed operation are required to form pixel circuits and driving circuits. Generally speaking, transistors with large on-state current are preferred to improve charging and discharging characteristics.

[0013] Furthermore, by reducing the area occupied by pixel circuits and driving circuits, it is possible to achieve higher resolution and narrower bezels in display devices. Therefore, it is preferable to use transistors with a small footprint.

[0014] One method to simultaneously increase the on-state current of a transistor and reduce its occupied area is to shorten the channel length. However, shortening the channel length of a transistor can easily lead to several negative effects collectively known as the short-channel effect. For example, the aforementioned hot carrier degradation becomes significant.

[0015] One objective of this invention is to provide a highly reliable semiconductor device, a driving circuit including the semiconductor device, or a display device including the semiconductor device. Another objective of this invention is to provide a semiconductor device, a driving circuit including the semiconductor device, or a display device including the semiconductor device capable of suppressing transistor characteristic degradation. Another objective of this invention is to provide a semiconductor device, a driving circuit including the semiconductor device, or a display device including the semiconductor device capable of suppressing hot carrier degradation. Another objective of this invention is to provide a semiconductor device or a driving circuit including the semiconductor device capable of improving the display quality of a display device. Another objective of this invention is to provide a semiconductor device or a display device including the semiconductor device capable of increasing the operating speed of a driving circuit. Another objective of this invention is to provide a semiconductor device, a driving circuit including the semiconductor device, or a display device including the semiconductor device with reduced power consumption. Another objective of this invention is to provide a semiconductor device, a driving circuit including the semiconductor device, or a display device including the semiconductor device that achieves miniaturization. Finally, one objective of this invention is to provide a novel semiconductor device, a driving circuit including the semiconductor device, or a display device including the semiconductor device.

[0016] Furthermore, the description of the foregoing objectives does not preclude the existence of other objectives. Note that one embodiment of the invention does not necessarily require achieving all of the foregoing objectives. Other objectives besides those described above can be readily apparent from the description in this specification, drawings, or claims.

[0017] means of solving technical problems (1)

[0019] One aspect of the present invention is a semiconductor device including a first transistor, a second transistor, and a third transistor, wherein the first transistor includes a first gate, a second gate opposite to the first gate via a channel forming region of the first transistor, a first source, and a first drain; the second transistor includes a third gate, a second source, and a second drain; the third transistor includes a fourth gate, a third source, and a third drain; one of the first source and the first drain is electrically connected to one of the second source and the second drain; the other of the first source and the first drain is electrically connected to one of the third source and the third drain; the first gate is electrically connected to the third gate; and the second gate is electrically connected to the other of the first source and the first drain. (2)

[0021] In addition, in (1) above, the second transistor may also include a fifth gate opposite to the third gate across the channel forming region of the second transistor, and the fifth gate may also be electrically connected to the third gate. (3)

[0023] In addition, in (1) or (2) above, the other of the second source and the second drain can also be supplied with a first potential, the other of the third source and the third drain can also be supplied with a second potential higher than the first potential, the first gate and the third gate can also be supplied with a first pulse signal, and the fourth gate can also be supplied with a second pulse signal with a different timing from the first pulse signal. (4)

[0025] In addition, in (1) or (2) above, the thickness of the gate insulating film of the second gate may be greater than the thickness of the gate insulating film of the first gate. (5)

[0027] In addition, in (1) or (2) above, the channel lengths of the first transistor and the second transistor may be less than the channel length of the third transistor. (6)

[0029] In addition, in (1) or (2) above, the channel forming region of the first transistor may also contain an oxide semiconductor. (7)

[0031] One aspect of the present invention is a semiconductor device including a first transistor, a second transistor, and a third transistor, wherein the first transistor includes a first gate, a second gate opposite to the first gate via a channel forming region of the first transistor, a first source, and a first drain; the second transistor includes a third gate, a second source, and a second drain; the third transistor includes a fourth gate, a third source, and a third drain; one of the first source and the first drain is electrically connected to one of the second source and the second drain; the other of the second source and the second drain is electrically connected to one of the third source and the third drain; the first gate is electrically connected to the third gate; and the second gate is electrically connected to the other of the first source and the first drain. (8)

[0033] Additionally, in (7) above, the second transistor may also include a fifth gate opposite to the third gate, which is separated from the channel forming region of the second transistor, and the fifth gate may also be electrically connected to the third gate. (9)

[0035] In addition, in (7) or (8) above, the other of the third source and the third drain can also be supplied with a first potential, the other of the first source and the first drain can also be supplied with a second potential higher than the first potential, the first gate and the third gate can also be supplied with a first pulse signal, and the fourth gate can also be supplied with a second pulse signal with a different timing from the first pulse signal. (10)

[0037] In addition, in (7) or (8) above, the thickness of the gate insulating film of the second gate may be greater than the thickness of the gate insulating film of the first gate. (11)

[0039] In addition, in (7) or (8) above, the channel lengths of the first transistor and the second transistor may be less than the channel length of the third transistor. (12)

[0041] In addition, in (7) or (8) above, the channel forming region of the first transistor may also contain an oxide semiconductor.

[0042] Invention Effects

[0043] According to one aspect of the present invention, a highly reliable semiconductor device, a driving circuit including the semiconductor device, or a display device including the semiconductor device can be provided. Additionally, a semiconductor device, a driving circuit including the semiconductor device, or a display device including the semiconductor device can be provided that can suppress the degradation of transistor characteristics. Furthermore, a semiconductor device, a driving circuit including the semiconductor device, or a display device including the semiconductor device can be provided that can suppress the degradation of hot carriers. Furthermore, a semiconductor device or a driving circuit including the semiconductor device can be provided that can improve the display quality of the display device. Furthermore, a semiconductor device or a display device including the semiconductor device can be provided that can improve the operating speed of the driving circuit. Furthermore, a semiconductor device, a driving circuit including the semiconductor device, or a display device including the semiconductor device can be provided that reduces power consumption. Furthermore, a semiconductor device, a driving circuit including the semiconductor device, or a display device including the semiconductor device can be provided that achieves miniaturization. Furthermore, a novel semiconductor device, a driving circuit including the semiconductor device, or a display device including the semiconductor device can be provided.

[0044] Note that the description of the above effects does not preclude the existence of other effects. Note that one embodiment of the invention does not necessarily require all of the above effects. Other effects besides those described above are readily apparent from the description in this specification, drawings, or claims, and can be extracted from the description in this specification, drawings, or claims. Attached Figure Description

[0045] Figure 1A This is a circuit diagram illustrating an example of the structure of a semiconductor device. Figure 1B This is a timing diagram illustrating an example of the operation of a semiconductor device.

[0046] Figures 2A to 2D This is a circuit diagram illustrating an example of the operation of a semiconductor device.

[0047] Figures 3A to 3D This is a circuit diagram illustrating an example of the structure of a semiconductor device.

[0048] Figure 4A This is a circuit diagram illustrating an example of the structure of a semiconductor device. Figure 4B This is a timing diagram illustrating an example of the operation of a semiconductor device.

[0049] Figures 5A to 5D This is a circuit diagram illustrating an example of the operation of a semiconductor device.

[0050] Figures 6A to 6D This is a circuit diagram illustrating an example of the structure of a semiconductor device.

[0051] Figure 7A This is a circuit diagram illustrating an example of the structure of a semiconductor device. Figure 7B This is a timing diagram illustrating an example of the operation of a semiconductor device.

[0052] Figure 8A and Figure 8B This is a circuit diagram illustrating an example of the structure of a semiconductor device.

[0053] Figure 9A and Figure 9B This is a circuit diagram illustrating an example of the structure of a semiconductor device.

[0054] Figure 10A and Figure 10B This is a circuit diagram illustrating an example of the structure of a semiconductor device.

[0055] Figure 11A This is a top view showing an example of the structure of a semiconductor device. Figure 11B and Figure 11C This is a cross-sectional view showing an example of the structure of a semiconductor device.

[0056] Figure 12A This is a top view showing an example of the structure of a semiconductor device. Figure 12B This is a cross-sectional view showing an example of the structure of a semiconductor device.

[0057] Figure 13A This is a top view showing an example of the structure of a semiconductor device. Figure 13B and Figure 13C This is a cross-sectional view showing an example of the structure of a semiconductor device.

[0058] Figure 14 This is a cross-sectional view showing an example of the structure of a semiconductor device.

[0059] Figure 15 This is a cross-sectional view showing an example of the structure of a semiconductor device.

[0060] Figure 16A This is a top view showing an example of the structure of a semiconductor device. Figure 16B This is a cross-sectional view showing an example of the structure of a semiconductor device.

[0061] Figure 17A and Figure 17B This is a top view showing an example of the structure of a semiconductor device.

[0062] Figure 18A This is a top view showing an example of the structure of a semiconductor device. Figure 18B This is a cross-sectional view showing an example of the structure of a semiconductor device.

[0063] Figure 19A This is a top view showing an example of the structure of a semiconductor device. Figure 19B This is a cross-sectional view showing an example of the structure of a semiconductor device.

[0064] Figure 20A This is a top view showing an example of the structure of a semiconductor device. Figure 20B This is a cross-sectional view showing an example of the structure of a semiconductor device.

[0065] Figure 21A This is a top view showing an example of the structure of a semiconductor device. Figure 21B This is a cross-sectional view showing an example of the structure of a semiconductor device.

[0066] Figure 22A This is a perspective view showing an example of the structure of a display device. Figures 22B to 22F This is a top view showing an example of pixel arrangement.

[0067] Figures 23A to 23E This is a block diagram illustrating an example of the structure of a display device.

[0068] Figures 24A to 24C and Figure 24E This is a circuit diagram illustrating an example of the structure of a semiconductor device. Figure 24D This is a timing diagram illustrating an example of the operation of a semiconductor device.

[0069] Figure 25 This is a circuit diagram illustrating an example of the structure of a semiconductor device.

[0070] Figure 26 This is a circuit diagram illustrating an example of the structure of a semiconductor device.

[0071] Figure 27 This is a circuit diagram illustrating an example of the structure of a semiconductor device.

[0072] Figure 28 This is a circuit diagram illustrating an example of the structure of a semiconductor device.

[0073] Figure 29 This is a circuit diagram illustrating an example of the structure of a semiconductor device.

[0074] Figure 30 This is a circuit diagram illustrating an example of the structure of a semiconductor device.

[0075] Figure 31 This is a circuit diagram illustrating an example of the structure of a semiconductor device.

[0076] Figure 32 This is a circuit diagram illustrating an example of the structure of a semiconductor device.

[0077] Figure 33 This is a circuit diagram illustrating an example of the structure of a semiconductor device.

[0078] Figure 34 This is a circuit diagram illustrating an example of the structure of a semiconductor device.

[0079] Figure 35 This is a circuit diagram illustrating an example of the structure of a semiconductor device.

[0080] Figure 36 This is a circuit diagram illustrating an example of the structure of a semiconductor device.

[0081] Figure 37 This is a circuit diagram illustrating an example of the structure of a semiconductor device.

[0082] Figure 38 This is a cross-sectional view showing an example of the structure of a display device.

[0083] Figure 39A and Figure 39B This is a cross-sectional view showing an example of the structure of a display device.

[0084] Figure 40A and Figure 40B This is a cross-sectional view showing an example of the structure of a display device.

[0085] Figures 41A to 41D This is a diagram illustrating an example of an electronic device.

[0086] Figures 42A to 42F This is a diagram illustrating an example of an electronic device.

[0087] Figures 43A to 43G This is a diagram illustrating an example of an electronic device.

[0088] Figure 44A and Figure 44B This is a graph showing the Id-Vg characteristics of a transistor in a SPICE model.

[0089] Figure 45A and Figure 45B This is a diagram showing the circuit simulation results of a semiconductor device. Detailed Implementation

[0090] In this specification and the like, a semiconductor device refers to a device that utilizes the properties of semiconductors, such as a circuit that includes semiconductor elements (e.g., transistors or diodes) or a device that includes such a circuit. Furthermore, a semiconductor device refers to any device capable of functioning by utilizing the properties of semiconductors. Examples of semiconductor devices include integrated circuits that include semiconductor elements, chips that include integrated circuits, electronic components that house chips in packages, or electronic devices that mount electronic components. Additionally, display devices, light-emitting devices, energy storage devices, optical devices, imaging devices, lighting devices, arithmetic devices, control devices, storage devices, input devices, output devices, input / output devices, signal processing devices, electronic computers, or electronic devices are themselves semiconductor devices, and sometimes include semiconductor devices.

[0091] Hereinafter, embodiments will be described with reference to the accompanying drawings. Note that embodiments can be implemented in many different forms. Therefore, those skilled in the art will readily understand that the manner and details can be varied in many ways without departing from its spirit and scope. Thus, one aspect of the present invention should not be construed as being limited to the content described in the embodiments.

[0092] Furthermore, the structures shown in each embodiment in this specification and the like can be appropriately combined with the structures shown in other embodiments to constitute a mode of the present invention. Additionally, when multiple structures are shown in one embodiment, these structures can be appropriately combined to constitute a mode of the present invention.

[0093] Note that, regarding the accompanying drawings illustrating the embodiments, in the structure of the invention, the same reference numerals are sometimes used in different drawings to denote the same parts or parts having the same function, thereby omitting repeated descriptions. Furthermore, in the drawings, when parts having the same function are indicated, the same shading lines are sometimes used, for example, without specifically adding reference numerals. For example, in perspective views or top views (also called "plan views"), illustrations of some constituent elements are sometimes omitted for clarity. For example, descriptions of some hidden lines in the drawings are sometimes omitted. Additionally, for example, descriptions of shading lines, etc., in the drawings are sometimes omitted.

[0094] In the accompanying drawings, sizes, layer thicknesses, or areas are sometimes exaggerated for clarity. Therefore, the drawings are not limited to the dimensions or aspect ratios shown. Furthermore, ideal examples are schematically illustrated in the drawings, and the invention is not limited to the shapes or values ​​shown. For example, in actual manufacturing processes, layers or resist masks are sometimes unintentionally thinned due to processes such as etching, but this is sometimes not reflected in the drawings for ease of understanding. Additionally, in actual circuit operation, voltage or current non-uniformity is sometimes caused by noise or timing deviations, but these are sometimes not reflected in the drawings for ease of understanding.

[0095] In this specification and accompanying drawings, the constituent elements are categorized according to function and represented as independent constituent elements. However, it is difficult to categorize constituent elements according to function, as sometimes a constituent element involves multiple functions or multiple constituent elements involve a single function. Therefore, the constituent elements shown in this specification and accompanying drawings are not limited to their description, and wording may be appropriately changed as needed.

[0096] In this specification and accompanying drawings, when multiple constituent elements use the same symbol and it is necessary to distinguish them, sometimes an identification symbol such as "A", "b", "_1", "[n]", or "[m,n]" is added to the symbol. Conversely, when describing the common content among multiple constituent elements for which an identification symbol is added, or when it is not necessary to distinguish them, sometimes the identification symbol is omitted.

[0097] Note that in this specification, the term "on state" or "turn-on state" of a transistor refers, for example, to a state in which the source and drain of the transistor are electrically short-circuited, or to a state in which current can flow between the source and drain. For example, the following states are sometimes referred to as "on state": in an n-channel transistor, the voltage between the gate and source is higher than the threshold voltage; or in a p-channel transistor, the voltage between the gate and source is lower than the threshold voltage. Conversely, the term "off state," "disconnected state," or "turn-off state" of a transistor refers to a state in which the source and drain of the transistor are electrically disconnected. For example, the following states are sometimes referred to as "off state," "disconnected state," or "turn-off state": in an n-channel transistor, the voltage between the gate and source is lower than the threshold voltage; or in a p-channel transistor, the voltage between the gate and source is higher than the threshold voltage.

[0098] Furthermore, in this specification, the voltage between the gate and source (gate-source) is sometimes referred to as "gate voltage," the voltage between the drain and source (drain-source) is sometimes referred to as "drain voltage," and the voltage between the back gate and source (back gate-source) is sometimes referred to as "back gate voltage." Additionally, the current flowing between the drain and source is sometimes referred to as "drain current." Note that descriptions of high gate voltage, high drain voltage, and high back gate voltage for n-channel transistors can be appropriately converted to descriptions of low gate voltage, low drain voltage, and low back gate voltage for p-channel transistors. Similarly, descriptions of low gate voltage, low drain voltage, and low back gate voltage for n-channel transistors can be appropriately converted to descriptions of high gate voltage, high drain voltage, and high back gate voltage for p-channel transistors.

[0099] Furthermore, in this specification and other documents, unless otherwise specified, the "off-state current" of a transistor refers to the drain current when the transistor is in the off state. Note that in this specification and other documents, the off-state current and the current flowing between the gate and the source and drain (also called gate leakage current) are sometimes referred to as leakage current.

[0100] (Implementation Method 1)

[0101] A semiconductor device according to one aspect of the present invention is described with reference to the accompanying drawings. For example, at least a portion of the semiconductor device according to one aspect of the present invention can be used in a display device. In particular, it can be used in a driving circuit included in a display device.

[0102] <Example 1 of semiconductor device structure>

[0103] Figure 1A This is a circuit diagram illustrating an example of the structure of a semiconductor device according to one aspect of the present invention.

[0104] like Figure 1A As shown, the semiconductor device 100A includes a switching section 101A and a switching section 102A. The switching section 101A includes transistors M11 and M12. The switching section 102A includes transistor M13.

[0105] Transistor M11 includes two gates (gate and back gate) that are opposite each other across a channel forming region.

[0106] One of the source and drain of transistor M11 is electrically connected to one of the source and drain of transistor M12. The other of the source and drain of transistor M11 is electrically connected to one of the source and drain of transistor M13 and wiring OUT11. The other of the source and drain of transistor M12 is electrically connected to wiring VLS. The other of the source and drain of transistor M13 is electrically connected to wiring VLD. The gate of transistor M11 is electrically connected to the gate of transistor M12 and wiring IN11. The gate of transistor M13 is electrically connected to wiring IN12. The back gate of transistor M11 is electrically connected to the other of the source and drain of transistor M11. One of the source and drain of transistor M11 is electrically connected to one of the source and drain of transistor M12 via wiring NL11.

[0107] In semiconductor device 100A, transistors M11, M12, and M13 are all n-channel transistors or p-channel transistors. Here, especially from the viewpoint that the hot carrier degradation in n-channel transistors is significant, the case where transistors M11, M12, and M13 are all n-channel transistors will be explained.

[0108] Here, in transistor M11, the threshold voltage drifts according to the back gate voltage. For example, when the back gate voltage is higher than 0V, the threshold voltage decreases compared to when the back gate voltage is 0V (also known as negative drift). Conversely, when the back gate voltage is lower than 0V, the threshold voltage increases compared to when the back gate voltage is 0V (also known as positive drift).

[0109] Furthermore, transistor M11 is enhancement-mode (normally off) when the back gate voltage is 0V. Additionally, transistors M12 and M13 are both normally off transistors. Therefore, their threshold voltages are greater than 0V.

[0110] Furthermore, transistors M11, M12, and M13 can be transistors that include a single-crystal semiconductor, a polycrystalline semiconductor, a microcrystalline semiconductor, or an amorphous semiconductor in the channel formation region, for example. Moreover, as the semiconductor, in addition to a single semiconductor whose main component is composed of a single element (e.g., silicon or germanium), compound semiconductors (e.g., silicon-germanium or gallium arsenide) or oxide semiconductors can also be used. Therefore, transistors M11, M12, and M13 can, for example, be transistors that include an oxide semiconductor in the channel formation region (OS transistors).

[0111] Note that examples of transistor structures that can be used for each of transistors M11, M12, and M13 will be described later in Embodiment 2.

[0112] Here, in a transistor with a high drain voltage applied, transistor characteristics sometimes deteriorate. For example, in a transistor with a high drain voltage applied in the off state, hot carriers are sometimes generated when the transistor is turned on. Therefore, by repeatedly switching the transistor between the on and off states, hot carrier degradation sometimes occurs, which alters the transistor characteristics with respect to the gate voltage due to the injection and accumulation of hot carriers in the gate insulating film. Thus, by reducing the drain voltage before the transistor is turned on, hot carrier degradation can be suppressed. In the semiconductor device 100A, the drain voltage can be reduced using an operation as described in the example below.

[0113] [Work Example 1]

[0114] Figure 1B This is a timing diagram illustrating an example of the operation of semiconductor device 100A. Figures 2A to 2D This is a circuit diagram illustrating an example of the operation of semiconductor device 100A.

[0115] In semiconductor device 100A, both wiring VLS and wiring VLD function as power lines. Wiring VLD is supplied with a potential higher than that supplied to wiring VLS. For example, wiring VLS is supplied with a potential VSS (sometimes simply referred to as VSS), and wiring VLD is supplied with a potential VDD (sometimes simply referred to as VDD). In this case, the difference between VDD and VSS is greater than the threshold voltage of the transistor. VSS can be, for example, ground potential.

[0116] Alternatively, a clock signal or pulse signal can be supplied to at least one of the wiring VLS and wiring VLD. Therefore, at least one of the wiring VLS and wiring VLD can also function as a signal line.

[0117] In addition, both wiring IN11 and wiring IN12 function as signal lines. Wiring IN11 and wiring IN12 are each supplied with pulse signals at different timings.

[0118] Alternatively, for example, a triangular wave or a sawtooth wave can be supplied to at least one of the wiring VLS, wiring VLD, wiring IN11, and wiring IN12. Therefore, the semiconductor device 100A can also be used, for example, in a pulse width modulation (PWM) circuit.

[0119] Note that in the operating instructions, rise time and fall time are generated when the potential changes, for example, due to the load (parasitic capacitance and parasitic resistance) of wiring, etc. Furthermore, even if the timing is shown as the same for two different operations, it does not necessarily mean that the timing is exactly the same. For example, even if slight delays caused by signal delays in wiring are included, they can sometimes be considered as the same timing.

[0120] In addition, for ease of understanding, periods are sometimes shown with the same length in a timing diagram, but the length of each period can also be different.

[0121] Figure 1B The timing diagram shown illustrates the potential status (VDD or VSS) supplied to each of the wiring VLD, wiring VLS, wiring IN11, and wiring IN12 during each period of operation. Additionally, the potential changes for wiring OUT11 and wiring NL11 are shown.

[0122] in addition, Figures 2A to 2D This shows the potentials of wiring VLD, wiring VLS, wiring IN11, wiring IN12, wiring OUT11, and wiring NL11 at various points in time during operation. Sometimes, a potential symbol (also called a potential symbol) such as "VDD" or "VSS" is displayed near each wiring in a framed form near the wiring. Additionally, sometimes an "×" symbol is superimposed on transistors in the off state where the gate voltage is below 0V and drain current is not flowing. Furthermore, sometimes a "△" symbol and a dashed arrow are superimposed on transistors where the gate voltage is below 0V and drain current is flowing.

[0123] Before period T11, wiring VLS, wiring IN11, and wiring IN12 are all supplied with VSS, and wiring VLD is supplied with VDD. Therefore, transistors M11, M12, and M13 are all in the off state. Additionally, the potentials of wiring OUT11 and wiring NL11 are all VSS. This represents the state of semiconductor device 100A at this time. Figure 2A The potential of each trace at time T1a is shown. Note that in the following operating instructions, the potentials of previous periods are maintained unless otherwise specified regarding the potential of each trace.

[0124] During T11, wiring IN12 is supplied with VDD. Therefore, transistor M13 becomes on, and the potential of wiring OUT11 becomes VDD. Note that for simplicity, the potential of wiring OUT11 is represented as "VDD," but it is actually "VDD - the threshold voltage of transistor M13." Therefore, the potential of wiring OUT11 can also be made "VDD" by supplying "VDD + the threshold voltage of the transistor" to wiring IN12.

[0125] Here, in transistor M11, the back gate and drain are electrically connected, resulting in "back gate voltage = drain voltage," and the threshold voltage drifts in the negative direction. At this time, the drift is in the negative direction to the extent that the drain current flows. Furthermore, in transistors like M11 where "back gate voltage = drain voltage," the occurrence of hot carriers is sometimes suppressed, thus reducing the likelihood of hot carrier degradation.

[0126] Therefore, the potential of wiring NL11 gradually increases according to the drain current of transistor M11. Here, when the potential increase of wiring NL11 is "vm", the potential of wiring NL11 is "VSS+vm", the gate voltage of transistor M11 is "-vm", and the back gate voltage is "VDD-VSS-vm". Therefore, as the potential of wiring NL11 increases, the gate voltage and back gate voltage of transistor M11 decrease. In addition, due to the decrease in back gate voltage, the threshold voltage drifts in the positive direction. As the state of semiconductor device 100A at this time, Figure 2B The potential of each wire at time T1b is shown.

[0127] Then, when the potential rise of wiring NL11 reaches "VM", transistor M11 turns off, and no drain current flows. Therefore, the potential of wiring NL11 becomes "VSS+VM", the gate voltage of transistor M11 becomes "-VM", and the back gate voltage becomes "VDD-VSS-VM". Note that "VM" is greater than 0V and less than "VDD-VSS". Therefore, the potential of wiring NL11 becomes the midpoint between VDD and VSS. This represents the state of semiconductor device 100A at this point. Figure 2C The potential of each wire at time T1c is shown.

[0128] Next, wiring IN12 is supplied with VSS. As a result, transistor M13 becomes off, and wiring OUT11 becomes floating. At this time, the drain voltage of transistor M11 is "VDD-VSS-VM", and the drain voltage of transistor M12 is "VM". Therefore, the drain voltages of transistors M11 and M12 are both lower than "VDD-VSS".

[0129] During period T12, wiring IN11 is supplied with VDD. Therefore, transistors M11 and M12 become active, and the potentials of wirings NL11 and OUT11 become VSS. This represents the state of semiconductor device 100A at this time. Figure 2D The potential of each wire is shown at time T1d.

[0130] Next, wiring IN11 is supplied to VSS. As a result, transistors M11 and M12 are both turned off, and wiring OUT11 becomes floating.

[0131] Here, in a transistor, when at least one of the gate voltage and drain voltage changes, it becomes a state where a high drain voltage is applied and a low gate voltage exceeding a threshold voltage is applied, thus making it easier for hot carriers to occur. For example, the higher the drain voltage applied before becoming on, the easier it is for hot carriers to occur after becoming on (i.e., after the gate voltage exceeds the threshold voltage).

[0132] In one aspect of the invention, the operation of the aforementioned period T11 reduces the drain voltages of transistors M11 and M12 before they become turn-on. Therefore, hot carrier degradation can be suppressed, thereby improving reliability.

[0133] Thus, in one embodiment of the present invention, by including two transistors connected in series, such as the switching section 101A included in the semiconductor device 100A, and electrically connecting the back gate of one transistor to its drain, the drain voltage of the transistor can be reduced, thereby suppressing the degradation of transistor characteristics. In other words, it is not necessary to add additional transistors to reduce the drain voltages of the two transistors connected in series. Therefore, reliability can be improved while suppressing the increase in the area occupied by the drive circuit.

[0134] To satisfy the above working example, the condition 0V < "vm" ≤ "VM" < "VDD - VSS" must be met. Therefore, the drift amount of the threshold voltage of transistor M11 caused by the back gate voltage needs to be appropriately set. For example, the "threshold voltage drift amount" is proportional to the "back gate capacitance / gate capacitance". Therefore, for example, in transistor M11, to achieve a negative drift in a manner that satisfies the above condition, the back gate capacitance can be made smaller than the gate capacitance. For example, the thickness of the back gate insulating film can be made greater than the thickness of the gate insulating film. Furthermore, for example, the relative permittivity of the back gate insulating film can be made smaller than the relative permittivity of the back gate insulating film.

[0135] Furthermore, one embodiment of the present invention has a structure in which transistor M11 and transistor M12 are connected in series. Therefore, for example, a structure that increases the on-state current of transistors M11 and M12 can be employed. This allows for the increase of on-state current while suppressing hot carrier degradation in transistors M11 and M12. In other words, it enables an improvement in the operating speed and reliability of the semiconductor device.

[0136] For example, the channel length of at least one of transistors M11 and M12 can be shorter than the channel length of transistor M13. Additionally, in transistor M11, when the back gate voltage equals the drain voltage, hot carrier degradation is sometimes less likely to occur. Therefore, for example, the channel length of transistor M11 can also be shorter than the channel length of transistor M12.

[0137] Furthermore, for example, the channel width of at least one of transistors M11 and M12 can be greater than the channel width of transistor M13. Additionally, the "channel width / channel length" ratio of at least one of transistors M11 and M12 can be greater than the "channel width / channel length" ratio of transistor M13. Furthermore, in transistor M11, when the gate voltage in the on-state decreases, the on-state current sometimes decreases. That is, the on-state current of transistor M11 sometimes becomes a speed limiter. In this case, for example, the channel width of transistor M11 can be greater than the channel width of transistor M12. Furthermore, the "channel width / channel length" ratio of transistor M11 can be greater than the "channel width / channel length" ratio of transistor M12. Additionally, in transistor M11, when the threshold voltage drifts negatively according to the back-gate voltage, the on-state current sometimes increases. That is, the on-state current of transistor M12 sometimes becomes a speed limiter. In this case, for example, the channel width of transistor M12 can be greater than the channel width of transistor M11. Alternatively, the "channel width / channel length" of transistor M12 can be made greater than the "channel width / channel length" of transistor M11.

[0138] [Example 1 of the variation]

[0139] Figures 3A to 3D These are all variations of the semiconductor device 100A. One aspect of the semiconductor device of the present invention achieves its function and effect by utilizing the back gate voltage of transistor M11 to shift the threshold voltage, and various structures can be employed within the range capable of achieving this function and effect.

[0140] like Figure 3A and Figure 3B As shown, transistors M12 and M13 may each include a back gate. In this case, for example, as... Figure 3A As shown, the back gate can also be electrically connected to the gate. The back gate is then supplied with the same potential as the gate, thereby increasing the on-state current. Therefore, for example, because the on-state current of transistor M12 increases, the channel width of transistor M12 can be smaller than the channel width of at least one of transistors M11 and M13. Furthermore, because the on-state current of transistor M13 increases, the channel width of transistor M13 can be smaller than the channel width of at least one of transistors M11 and M12. Therefore, reliability can be improved while suppressing the increase in the occupied area of ​​the drive circuit.

[0141] In addition, for example, such as Figure 3B As shown, the back gate can also be electrically connected to the source. In this case, the back gate is supplied with the same potential as the source, thus the electric field generated outside the transistor is less likely to affect the channel formation region, thereby stabilizing the electrical characteristics and improving reliability. Furthermore, in Figure 3B In the illustrated structure, for example, even when wiring VLS is used as a signal line and the source or drain functions of transistors M11 and M12 are switched, the drain voltage of each transistor can be reduced. That is, for example, even when the potential of wiring OUT11 is VSS and the potential of wiring VLS changes from VSS to VDD, transistor M12 still satisfies "back gate voltage = drain voltage," thereby reducing the drain voltage of both transistors M11 and M12. Therefore, reliability can be improved.

[0142] Furthermore, although not illustrated, the threshold voltage can be changed by supplying an arbitrary potential to the back gate. For example, a potential higher than VDD can be supplied in the on-state. This increases the on-state current. Therefore, for example, because the on-state current of transistor M12 increases, the channel width of transistor M12 can be made smaller than the channel width of at least one of transistors M11 and M13. Furthermore, because the on-state current of transistor M13 increases, the channel width of transistor M13 can be made smaller than the channel width of at least one of transistors M11 and M12. Therefore, reliability can be improved while suppressing the increase in the occupied area of ​​the drive circuit.

[0143] When both transistors M12 and M13 include a back gate, this back gate can be manufactured simultaneously with the back gate included in transistor M11. That is, no additional processes or masks are required, so the above structure can be achieved without increasing process costs.

[0144] In addition, such as Figure 3C As shown, the back gate of transistor M11 can also be electrically connected to wiring VLB. In this case, a potential higher than VSS can be supplied to wiring VLB. For example, a potential that makes the back gate voltage greater than 0V can also be supplied. Furthermore, for example, a potential higher than VDD can also be supplied. The amount of threshold voltage drift can be adjusted according to the potential supplied to wiring VLB. As a result, for example, the design freedom of the back gate insulating film thickness and relative permittivity can be increased.

[0145] Furthermore, for example, by increasing the potential supplied to wiring VLB when transistor M11 is in the on-state, the on-state current can be increased. Thus, for example, the channel width of transistor M11 can be made smaller than the channel width of at least one of transistors M12 and M13. Therefore, reliability can be improved while suppressing the increase in the occupied area of ​​the drive circuit.

[0146] In addition, such as Figure 3DAs shown, a p-channel transistor can also be used as transistor M13. Therefore, for example, transistors M11 and M12 can operate complementaryly to transistor M13. This allows wiring IN11 and IN12 to be supplied with the same potential, thereby enabling a reduction in circuit size. In other words, wiring IN11 and IN12 can also be electrically connected to each other, for example. Furthermore, the gates of transistors M11, M12, and M13 can also be electrically connected to each other.

[0147] Thus, the semiconductor device of one aspect of the present invention can adopt various structures. Furthermore, not limited to the structures described above, semiconductor devices with appropriate combinations of these structures can be employed.

[0148] <Structure Example of a Semiconductor Device 2>

[0149] Figure 4A This is a circuit diagram illustrating other structural examples of a semiconductor device according to one aspect of the present invention.

[0150] like Figure 4A As shown, the semiconductor device 100B includes a switching section 101B and a switching section 102B. The switching section 101B includes transistors M21 and M22. The switching section 102B includes transistor M23.

[0151] Transistor M21 includes two gates (gate and back gate) that are opposite each other across a channel forming region.

[0152] One of the source and drain of transistor M21 is electrically connected to one of the source and drain of transistor M22. The other of the source and drain of transistor M21 is electrically connected to wiring VLD. The other of the source and drain of transistor M22 is electrically connected to one of the source and drain of transistor M23 and wiring OUT21. The other of the source and drain of transistor M23 is electrically connected to wiring VLS. The gate of transistor M21 is electrically connected to the gate of transistor M22 and wiring IN22. The gate of transistor M23 is electrically connected to wiring IN21. The back gate of transistor M21 is electrically connected to the other of the source and drain of transistor M21. One of the source and drain of transistor M21 is electrically connected to one of the source and drain of transistor M22 via wiring NL21.

[0153] Therefore, semiconductor device 100B is also a variation of semiconductor device 100A. Thus, the description of semiconductor device 100A described above can be appropriately referenced, and therefore detailed descriptions are sometimes omitted here.

[0154] Furthermore, switch section 101B is equivalent to switch section 101A, and switch section 102B is equivalent to switch section 102A. That is, transistor M21 is equivalent to transistor M11, transistor M22 is equivalent to transistor M12, and transistor M23 is equivalent to transistor M13. In addition, wiring IN21 is equivalent to wiring IN11, wiring IN22 is equivalent to wiring IN12, and wiring OUT21 is equivalent to wiring OUT11.

[0155] [Work Example 2]

[0156] Figure 4B This is a timing diagram illustrating an example of the operation of semiconductor device 100B. Figures 5A to 5D This is a circuit diagram illustrating an example of the operation of semiconductor device 100B.

[0157] Figure 4B The timing diagram shown illustrates the potential status (VDD or VSS) supplied to each of the wiring VLD, wiring VLS, wiring IN21, and wiring IN22 during each period of operation. Additionally, the potential changes for wiring OUT21 and wiring NL21 are shown.

[0158] in addition, Figures 5A to 5D The voltages of wiring VLD, wiring VLS, wiring IN21, wiring IN22, wiring OUT21, and wiring NL21 at various points in time during operation are shown.

[0159] Before period T21, wiring VLD, wiring VLS, wiring IN21, and wiring IN22 are all supplied with VSS. Therefore, transistors M21, M22, and M23 are all in the off state. Additionally, the potentials of wiring OUT21 and wiring NL21 are all VSS. This represents the state of semiconductor device 100B at this time. Figure 5A The potential of each trace at time T2a is shown. Note that in the following operating instructions, the potentials of previous periods are maintained unless otherwise specified.

[0160] During period T21, the wiring VLD is supplied to VDD.

[0161] Here, in transistor M21, the back gate and drain are electrically connected, resulting in "back gate voltage = drain voltage," and the threshold voltage drifts in the negative direction. At this time, the voltage drifts in the negative direction to the extent that the drain current flows.

[0162] Therefore, the potential of wiring NL21 gradually increases according to the drain current of transistor M21. Here, when the potential increase of wiring NL21 is "vm", the potential of wiring NL21 is "VSS+vm", the gate voltage of transistor M21 is "-vm", and the back gate voltage is "VDD-VSS-vm". Therefore, as the potential of wiring NL21 increases, the gate voltage and back gate voltage of transistor M21 decrease. Furthermore, due to the decrease in the back gate voltage, the threshold voltage shifts in the positive direction. This is the state of semiconductor device 100B at this time. Figure 5B The potential of each wire is shown at time T2b.

[0163] Then, when the potential rise of wiring NL21 reaches "VM", transistor M21 becomes off, and no drain current flows. Therefore, the potential of wiring NL21 becomes "VSS+VM", the gate voltage of transistor M21 becomes "-VM", and the back gate voltage becomes "VDD-VSS-VM". Note that "VM" is greater than 0V and less than "VDD-VSS". Therefore, the potential of wiring NL21 becomes the intermediate potential between VDD and VSS. This represents the state of semiconductor device 100B at this time. Figure 5C The potential of each wire is shown at time T2c.

[0164] During period T22, wiring IN22 is supplied with VDD. Therefore, transistors M21 and M22 become active, and the potentials of wirings NL21 and OUT21 become VDD. This represents the state of semiconductor device 100B at this time. Figure 5D The potential of each wire is shown at time T2d.

[0165] Next, wiring IN22 is supplied to VSS. As a result, transistors M21 and M22 are both turned off, and wiring OUT21 becomes floating.

[0166] Note that, although not shown, by supplying VDD to wiring IN21 after period T22, transistor M23 becomes turn-on, and the potential of wiring OUT21 becomes VSS.

[0167] In one embodiment of the invention, the operation of the aforementioned period T21 reduces the drain voltages of transistors M21 and M22 before they become turn-on. Therefore, hot carrier degradation can be suppressed, thereby improving reliability.

[0168] [Example 2]

[0169] Figures 6A to 6DThese are all variations of the semiconductor device 100B. One aspect of the semiconductor device of the present invention achieves its function and effect by utilizing the back gate voltage of transistor M21 to shift the threshold voltage, and various structures can be employed within the range capable of achieving this function and effect.

[0170] Notice, Figures 6A to 6D The modified examples of the semiconductor device 100B shown are equivalent to the above. Figures 3A to 3D Each of the shown semiconductor devices 100A is a modified example. Therefore, the above description can be used as a reference, and detailed explanations are omitted here. That is to say, regarding... Figure 6A The semiconductor device 100B shown can be referred to Figure 3A Description of the semiconductor device 100A shown. Additionally, regarding... Figure 6B The semiconductor device 100B shown can be referred to Figure 3B Description of the semiconductor device 100A shown. Additionally, regarding... Figure 6C The semiconductor device 100B shown can be referred to Figure 3C Description of the semiconductor device 100A shown. Additionally, regarding... Figure 6D The semiconductor device 100B shown can be referred to Figure 3D Description of the semiconductor device 100A shown.

[0171] <Application examples of driver circuits>

[0172] Figure 7A This is a circuit diagram illustrating an example of the structure of a driving circuit for a semiconductor device that can be used in accordance with one aspect of the present invention.

[0173] Figure 7A The driving circuit 110 shown includes transistors M31, M32, M33, M34, M35 and M36.

[0174] One of the source and drain of transistor M31 is electrically connected to one of the source and drain of transistor M32 and the gate of transistor M35. One of the source and drain of transistor M33 is electrically connected to one of the source and drain of transistor M34, the gate of transistor M32, and the gate of transistor M35. One of the source and drain of transistor M35 is electrically connected to one of the source and drain of transistor M36 and wiring OUT31. The other of the source and drain of transistor M31 and the other of the source and drain of transistor M33 are electrically connected to wiring VLD. The other of the source and drain of transistor M32, the other of the source and drain of transistor M34, and the other of the source and drain of transistor M36 are electrically connected to wiring VLS. The gates of transistor M31 and M34 are electrically connected to wiring IN31. The gate of transistor M33 is electrically connected to wiring IN32. The other of the source and drain of transistor M35 is electrically connected to wiring CK31. Additionally, one of the source and drain of transistor M31, one of the source and drain of transistor M32, and the gate of transistor M35 are electrically connected to each other via wiring NL31. One of the source and drain of transistor M33, one of the source and drain of transistor M34, the gate of transistor M32, and the gate of transistor M36 are electrically connected to each other via wiring NL32.

[0175] Both wiring VLS and wiring VLD are supplied with a power supply potential that makes the potential of wiring VLD higher than that of wiring VLS. Wiring IN31 and wiring IN32 are each supplied with pulse signals with different timings. Wiring CK31 is supplied with a clock signal. Wiring OUT31 outputs a pulse signal according to these signals.

[0176] Figure 7B This is a timing diagram illustrating an example of the operation of the drive circuit 110.

[0177] Figure 7B The timing diagram shown illustrates the potential status (VDD or VSS) supplied to each of wiring IN31, wiring IN32, and wiring CK31 during various periods of operation. Additionally, the potential changes for wiring NL31, wiring NL32, and wiring OUT31 are shown.

[0178] Before period T31, wiring VLD is supplied with VDD, and wiring VLS is supplied with VSS. Additionally, wiring IN31, IN32, and CK31 are all supplied with VSS. Therefore, transistors M31, M33, and M34 are all in the off state. Furthermore, wiring NL31 has a potential of VSS, and wiring NL32 has a potential of VDD. Therefore, transistors M32 and M36 are in the on state, and transistor M35 is in the off state. Therefore, wiring OUT31 has a potential of VSS. Note that in the following operating instructions, unless the potential of each wiring is mentioned, it can be considered as maintaining the potential of the previous period.

[0179] During T31, a clock signal is supplied to wiring CK31. At this time, transistor M35 is off and transistor M36 is on, so the potential of wiring OUT31 remains at VSS.

[0180] During T32, a pulse signal is supplied to wiring IN31, and a clock signal is supplied to wiring CK31. That is, wiring IN31 is supplied with VDD, thereby turning on transistors M31 and M34. Consequently, the potential of wiring NL32 becomes VSS, and transistors M32 and M36 become off. Conversely, the potential of wiring NL31 becomes VDD, and transistor M35 becomes on. Then, wiring IN31 is supplied with VSS, thereby turning off transistors M31 and M34. This maintains the potentials of wiring NL31 and NL32 to maintain the on state of transistor M35 and the off state of transistor M36. At this time, the potential of wiring CK31 is supplied to wiring OUT31 through transistor M35. That is, a clock signal is supplied to wiring OUT31.

[0181] During period T33, a pulse signal is supplied to wiring IN32, and a clock signal is supplied to wiring CK31. That is, wiring IN32 is supplied with VDD, thus turning transistor M33 on. Consequently, the potential of wiring NL32 becomes VDD, and both transistors M32 and M36 are turned on. Therefore, the potential of wiring NL31 becomes VSS, and transistor M35 is turned off. Then, wiring IN32 is supplied with VSS, thus turning transistor M33 off. This maintains the potentials of wiring NL31 and NL32 to maintain the off state of transistor M35 and the on state of transistor M36. At this time, transistor M35 is off and transistor M36 is on, so the potential of wiring OUT31 remains at VSS.

[0182] During the operation of the drive circuit 110, during period T31, transistors M31 and M34 are in the off state, and the drain voltage becomes "VDD-VSS". Therefore, during period T32, when a pulse signal is supplied to wiring IN31 and transistors M31 and M34 become on, hot carriers sometimes occur. Additionally, during period T32, transistors M32 and M33 are both in the off state, and the drain voltage becomes "VDD-VSS". Therefore, during period T33, when a pulse signal is supplied to wiring IN32 and transistors M32 and M33 become on, hot carriers sometimes occur.

[0183] Therefore, by using at least a portion of the aforementioned semiconductor devices 100A and 100B in the drive circuit 110, the drain voltage before the transistor becomes turn-on can be reduced, thereby suppressing hot carrier degradation. This improves the reliability of the display device using the drive circuit.

[0184] Figure 8A and Figure 8B These are circuit diagrams showing examples of the structure of using switch section 101A and switch section 101B in drive circuit 110.

[0185] Figure 8A The driving circuit 110A shown includes switching sections 101A_1 and 101A_2 replacing transistors M32 and M34. Switching sections 101A_1 and 101A_2 are both equivalent to switching section 101A. That is, transistors M32a and M34a are both equivalent to transistor M11, and transistors M32b and M34b are both equivalent to transistor M12.

[0186] In the drive circuit 110A, the drain voltages of transistors M32a and M32b before they become turn-on can be reduced, as illustrated in the example of the operation of the semiconductor device 100A described above. Additionally, the drain voltages of transistors M34a and M34b before they become turn-on can also be reduced.

[0187] Note that the use of this is shown here. Figure 3A The example shown is a structure of the switch section 101A. This allows for the suppression of the decrease in on-state current caused by the series connection of two transistors, thereby suppressing the decrease in the operating speed of the drive circuit 110A.

[0188] In the drive circuit 110A, the gate potential of transistor M35 sometimes rises above VDD. Even in this case, the drain voltages of transistors M32a and M32b can be reduced. Therefore, the reliability of the display device using the drive circuit 110A can be improved. Furthermore, it is not necessary to separately place transistors between the gate of transistor M35 and transistors M32a and M32b to suppress the rise of the drain voltages of transistors M32a and M32b. Therefore, the increase in the occupied area of ​​the drive circuit 110A can be suppressed.

[0189] Furthermore, in the drive circuit 110A, VDD is sometimes applied to the gate of transistor M36. Even in this case, the drain voltages of transistors M34a and M34b can be reduced. Therefore, the reliability of the display device using the drive circuit 110A can be improved.

[0190] Note that the illustrated structure of transistors M31 and M33 in the drive circuit 110A does not use the switching section 101B. In the drive circuit 110A, for example, if the potential supplied to the wiring VLD is a fixed potential VDD, transistors M31 and M33 may also omit the switching section 101B. This suppresses the increase in the area occupied by the drive circuit 110A. Therefore, miniaturization of the display device using the drive circuit 110A is possible.

[0191] Furthermore, an example of a structure in the driving circuit 110A without using switching sections 101A and 101B is shown. Here, when the driving circuit 110A is used in a display device, wiring OUT31 is electrically connected to the gates of the transistors included in each of the multiple pixels. Therefore, transistors M35 and M36 require a large on-state current. Therefore, by omitting switching sections 101A and 101B, the decrease in on-state current can be suppressed, and the operating speed of the driving circuit 110A can be increased. Additionally, the increase in the area occupied by the driving circuit 110A can be suppressed. Therefore, it is possible to achieve larger screens and higher resolutions in display devices using the driving circuit 110A.

[0192] Figure 8B This is a circuit diagram showing a modified example of the drive circuit 110A. Figure 8BThe driving circuit 110B shown includes switching units 101B_1, 101B_2, 101B_3, and 101A_3 replacing transistors M31, M33, M35, and M36. Switching units 101B_1, 101B_2, and 101B_3 are all equivalent to switching unit 101B. Switching unit 101A_3 is equivalent to switching unit 101A. That is, transistors M31a, M33a, and M35a are all equivalent to transistor M21, transistors M31b, M33b, and M35b are all equivalent to transistor M22, transistor M36a is equivalent to transistor M11, and transistor M36b is equivalent to transistor M12.

[0193] In the drive circuit 110B, the drain voltage of each transistor included in the drive circuit 110B before it becomes in the turn-on state can be reduced by the operation examples of the semiconductor device 100A and semiconductor device 100B described above.

[0194] Note that this shows that Figure 6A The switch 101B shown is used for transistors M31 and M33 and will Figure 3A The shown example of a switch section 101A used in transistor M36. This suppresses the decrease in on-state current caused by the series connection of two transistors, thereby suppressing the decrease in the operating speed of the drive circuit 110B. Furthermore, it shows a structure where... Figure 6B The shown switch section 101B is a structural example of a transistor M35. Therefore, even when the function of the source or drain switches according to the signal supplied to the wiring CK31, the drain voltage can be reduced. Thus, the reliability of the display device using the drive circuit 110B can be improved.

[0195] Here, in the drive circuit 110B, for example, when the potential supplied to the wiring VLD changes from VSS to VDD when the power supply rises, or when the wiring VLD is used as a signal line, the drain voltage can be reduced by using the switching unit 101B. This improves the reliability of the display device using the drive circuit 110B.

[0196] At this time, for example, the capacitance between the gate of transistor M21 and wiring NL21 can be increased in the switching section 101B used for the drive circuit 110B. For example, the parasitic capacitance between the gate and wiring NL21 can also be increased. In addition, a capacitor can be provided between the gate and wiring NL21. As a result, when transistors M21 and M22 are in the off state, the potential of wiring NL21 is lower than VDD due to capacitive coupling. That is, the drain voltage of transistors M21 and M22 can sometimes be reduced. As a result, the reliability of the display device using the drive circuit 110B can be improved.

[0197] Alternatively, you can also Figure 6A The switch 101B shown is used for transistor M35. This suppresses the decrease in on-state current caused by the series connection of the two transistors, thereby suppressing the decrease in the operating speed of the drive circuit 110B.

[0198] Furthermore, although not shown, in the drive circuit 110B, the wiring VLS (referred to herein as wiring VLS_1) electrically connected to the switch section 101A_3 and the wiring VLS (referred to herein as wiring VLS_2) electrically connected to both the switch section 101A_1 and the switch section 101A_2 can be different wirings from each other. In this case, for example, a fixed potential VSS can be supplied to wiring VLS_2, and wiring VLS_1 can be used as a signal line. At this time, it is also possible to... Figure 3B The switch 101A shown is used for transistor M36. Therefore, even when the source or drain function switches according to the signal supplied to wiring VLS_1, the drain voltage can be reduced. This improves the reliability of the display device using drive circuit 110B.

[0199] Note that the structure of the above-described driving circuit 110A and driving circuit 110B is only an example. In one aspect of the present invention, at least a portion of the transistors in the driving circuit 110 may use switching section 101A and switching section 101B, etc.

[0200] For example, at least a portion of the driving circuit of a semiconductor device using one aspect of the present invention can be used in a display device. Furthermore, it can be used, for example, in various devices such as input devices including touch sensors and storage devices including storage units. An example of a display device structure in which this driving circuit can be used will be described later in Embodiment 3.

[0201] The driving circuit of the semiconductor device according to one aspect of the present invention is not limited to the structural examples described above. The semiconductor device according to one aspect of the present invention can be used in driving circuits with various structures.

[0202] [Other application example 1]

[0203] Figure 9A and Figure 9B This is a circuit diagram illustrating an example of the structure of a driving circuit for a semiconductor device that can be used in accordance with one aspect of the present invention.

[0204] Figure 9A The driving circuit 116 shown includes transistors M61, M62, M63, M64, M65, M66, M67, M68, capacitors C61, C62, and C63.

[0205] The gate of transistor M61 is electrically connected to one of the source and drain of transistor M63 and one terminal of capacitor C61. One of the source and drain of transistor M61 is electrically connected to one of the source and drain of transistor M62, one terminal of capacitor C61, and wiring OUT61. The gate of transistor M62 is electrically connected to one of the source and drain of transistor M64, one of the source and drain of transistor M66, and one terminal of capacitor C62. The gate of transistor M64 is electrically connected to the other of the source and drain of transistor M63 and one of the source and drain of transistor M65. The gate of transistor M66 is electrically connected to one of the source and drain of transistor M67, one of the source and drain of transistor M68, and one terminal of capacitor C63. The other of the source and drain of transistor M62, the other of the source and drain of transistor M64, the other of the source and drain of transistor M67, the other of the source and drain of transistor M68, and the other terminal of capacitor C62 are electrically connected to wiring VLS. The other of the source and drain of transistor M61 and the gate of transistor M63 are electrically connected to wiring VLD. One of the source and drain of transistor M65 and the gate of transistor M68 are electrically connected to wiring IN61. The gate of transistor M65, the other of the source and drain of transistor M66, and the other terminal of capacitor C63 are electrically connected to wiring CK61. The gate of transistor M67 is electrically connected to wiring CK62.

[0206] Both wiring VLS and wiring VLD are supplied with a power supply potential that makes the potential of wiring VLD higher than that of wiring VLS. Wiring IN61 is supplied with a pulse signal. Wiring CK61 and wiring CK62 are each supplied with a clock signal of a different phase. Wiring OUT61 outputs a pulse signal according to these signals.

[0207] Figure 9B The drive circuit 116A shown illustrates the following structural example: used as transistors M61 and M65. Figure 6A The switch unit 101B shown is used as transistor M62, transistor M64, transistor M67, and transistor M68. Figure 3A The switch section 101A shown is used as transistor M66. Figure 6B The switch section 101B is shown. Therefore, Figure 9B The following structural example is shown: Transistor M61 is replaced by switch section 101B_1, transistor M62 by switch section 101A_2, transistor M64 by switch section 101A_4, transistor M65 by switch section 101B_5, transistor M66 by switch section 101B_6, transistor M67 by switch section 101A_7, and transistor M68 by switch section 101A_8. That is, transistors M62a, M64a, M67a, and M68a are equivalent to transistor M11, and transistors M62b, M64b, M67b, and M68b are equivalent to transistor M12. Furthermore, transistors M61a, M65a, and M66a are equivalent to transistor M21, and transistors M61b, M65b, and M66b are equivalent to transistor M22. Note that... Figure 9B The structure shown is just an example. The transistors that are at least part of the drive circuit 116A can be switching units 101A and 101B, etc.

[0208] In the drive circuit 116A, transistors M61, M62, and M64 are sometimes subjected to high drain voltages, so switching sections 101A and 101B can also be used. Furthermore, the source or drain functions of transistors M65 and M66 switch according to the signals supplied to wiring IN61 and wiring CK61. Therefore, transistors M65 and M66 can also be employed... Figure 6B The switch unit 101B shown has the same structure. In this way, by using the switch units 101A and 101B, the reliability of the drive circuit 116A and the display device using the pixel circuit can be improved.

[0209] Furthermore, by using the switch section 101B for transistor M65, the drain voltage can be reduced, thus sometimes eliminating the need for transistor M63. Therefore, the increase in the area occupied by the drive circuit 116A can be suppressed, and the display device using the drive circuit 116A can be miniaturized.

[0210] [Other Application Examples 2]

[0211] Figure 10A and Figure 10B This is a circuit diagram illustrating an example of the structure of a driving circuit for a semiconductor device that can be used in accordance with one aspect of the present invention.

[0212] Figure 10AThe driving circuit 117 shown includes transistors M71, M72, M73, M74, M75, M76, M77, M78, capacitor C71, and capacitor C72.

[0213] The gate of transistor M71 is electrically connected to the gate of transistor M74, one of the source and drain of transistor M75, one of the source and drain of transistor M76, and one terminal of capacitor C71. One of the source and drain of transistor M71 is electrically connected to one of the source and drain of transistor M72 and wiring OUT71. The gate of transistor M72 is electrically connected to one of the source and drain of transistor M73. The other of the source and drain of transistor M73 is electrically connected to one of the source and drain of transistor M74, the gate of transistor M75, one of the source and drain of transistor M77, one of the source and drain of transistor M78, and one terminal of capacitor C72. The other of the source and drain of transistor M71 and another terminal of capacitor C71 are electrically connected to wiring VLS_1. The other of the source and drain of transistor M74, the other of the source and drain of transistor M75, and another terminal of capacitor C72 are electrically connected to wiring VLS. The gate of transistor M73 and one of the source and drain of transistor M76 are electrically connected to wiring VLD. The gate of transistor M77 is electrically connected to wiring IN71. The gate of transistor M78 is electrically connected to wiring IN72. The other of the source and drain of transistor M72 is electrically connected to wiring CK71. The gate of transistor M76 is electrically connected to wiring CK72. The other of the source and drain of transistor M77 is electrically connected to wiring SE71. The other of the source and drain of transistor M78 is electrically connected to wiring SE72.

[0214] Wiring VLS_1, Wiring VLS_2, and Wiring VLD are all supplied with power potentials that make the potential of Wiring VLD higher than that of Wiring VLS_1 and Wiring VLS_2. Wiring IN71 and Wiring IN72 are each supplied with pulse signals with different timings. Wiring CK71 and Wiring CK72 are each supplied with clock signals with different phases. Wiring SE71 and Wiring SE72 are both supplied with selection signals. Wiring OUT71 outputs a pulse signal based on these signals.

[0215] Figure 10B The drive circuit 117A shown illustrates the following structural example: used as transistors M71, M74, and M75. Figure 3A The switch section 101A shown is used as transistor M72 and transistor M76. Figure 6A The switch section 101B shown is used as transistor M77 and transistor M78. Figure 6BThe switch section 101B is shown. Therefore, Figure 10B The following structural example is shown: Transistor M71 is replaced by switch section 101A_1, transistor M72 by switch section 101B_2, transistor M74 by switch section 101A_4, transistor M75 by switch section 101A_5, transistor M76 by switch section 101B_6, transistor M77 by switch section 101B_7, and transistor M78 by switch section 101A_8. That is, transistors M71a, M74a, M75a, and M78a are equivalent to transistor M11, and transistors M71b, M74b, M75b, and M78b are equivalent to transistor M12. Furthermore, transistors M72a, M76a, and M77a are equivalent to transistor M21, and transistors M72b, M76b, and M77b are equivalent to transistor M22. Note that... Figure 10B The structure shown is just an example. The transistors that are at least part of the drive circuit 117A can be switching units 101A and 101B, etc.

[0216] In the drive circuit 117A, transistors M71, M72, M74, M75, and M76 are sometimes subjected to high drain voltages, so switching sections 101A and 101B can also be used. Furthermore, the source or drain functions of transistors M77 and M78 switch according to the signals supplied to wiring SE71 and wiring SE72. Therefore, transistors M77 and M78 can also be employed... Figure 6B The switch unit 101B shown has the same structure. In this way, by using the switch units 101A and 101B, the reliability of the drive circuit 117A and the display device using the pixel circuit can be improved.

[0217] Furthermore, by using switch sections 101A and 101B for transistors M74, M77, and M78, the drain voltage can be reduced, thus sometimes eliminating the need for transistor M73. Therefore, the increase in the area occupied by the drive circuit 117A can be suppressed, and the display device using the drive circuit 117A can be miniaturized.

[0218] One aspect of the present invention is not limited to the above-described structure; at least a portion of each structure may be appropriately combined.

[0219] Additionally, one embodiment of the present invention includes a structure in which at least one of the gate, source, and drain of one or more transistors is not connected to any constituent element or is connected to any wiring. Furthermore, another embodiment of the present invention includes a structure in which no content is input to one or more wirings or any signal or potential is input.

[0220] Note that the semiconductor device according to one aspect of the present invention is not limited to the semiconductor device described in this embodiment. At least a portion of the structural examples, operational examples, and corresponding drawings shown in this embodiment can be appropriately combined with other structural examples, other operational examples, other drawings, and other embodiments shown in this specification, etc.

[0221] (Implementation Method 2)

[0222] In this embodiment, a semiconductor device according to one aspect of the present invention and the transistors included in the semiconductor device will be described with reference to FIGS. 11 to 13. At least a portion of the transistors shown in this embodiment can be used in semiconductor devices 100A and 100B, etc., shown in Embodiment 1 above.

[0223] <Example of transistor structure>

[0224] A semiconductor device according to one aspect of the present invention will be described. Figure 11A A top view of the semiconductor device 10 is shown. Figure 11B Show along Figure 11A The cross-sectional view of the section along the dotted line A1-A2 shown is shown. Figure 11C This shows a cross-sectional view along the dashed line B1-B2. Note that... Figure 11A In the diagram, some components of the semiconductor device 10 (such as insulating layers) are omitted. Regarding the top view of the semiconductor device, [the diagram is incomplete]. Figure 11A Similarly, some of the constituent elements are omitted in the following figures.

[0225] Semiconductor device 10 includes transistor 300, transistor 200, capacitor 350, and insulating layer 310. Transistor 300, transistor 200, and capacitor 350 are disposed on substrate 302. Transistor 300 and transistor 200 have different structures. In addition, transistor 300, transistor 200, and capacitor 350 can be formed using a portion of the same process.

[0226] Transistor 300 includes a conductive layer 304, an insulating layer 306, a semiconductor layer 308, a conductive layer 312a, and a conductive layer 312b. In transistor 300, conductive layer 304 is used as a gate electrode, and a portion of insulating layer 306 is used as a gate insulating layer. Conductive layer 312a is used as one of the source electrode and the drain electrode, and conductive layer 312b is used as the other of the source electrode and the drain electrode. The layers constituting transistor 300 can have a single-layer structure or a stacked structure.

[0227] A conductive layer 312a is disposed on a substrate 302, and an insulating layer 310 is disposed on the conductive layer 312a. The insulating layer 310 is disposed such that it covers the top surface and side surface of the conductive layer 312a. The insulating layer 310 has an opening 341 in the region overlapping with the conductive layer 312a, which extends to the conductive layer 312a. In other words, the conductive layer 312a is exposed in the opening 341.

[0228] A conductive layer 312b is disposed on the insulating layer 310. The conductive layer 312b has a region that overlaps with the conductive layer 312a across the insulating layer 310. The conductive layer 312b has an opening 343 in the region that overlaps with the conductive layer 312a. The opening 343 is disposed in the region that overlaps with the opening 341.

[0229] Openings 341 and 343 have a cylindrical shape with a circular or substantially circular top surface. This structure allows for miniaturization, high integration, high density, and miniaturization of semiconductor devices. Note that the sides of openings 341 and 343 are preferably perpendicular to the top surface of the conductive layer 312a.

[0230] At least a portion of the semiconductor layer 308 covers openings 341 and 343. The semiconductor layer 308 has regions that contact the top and side surfaces of the conductive layer 312b, the side surface of the insulating layer 310, and the top surface of the conductive layer 312a. The semiconductor layer 308 is electrically connected to the conductive layer 312a through openings 341 and 343. The semiconductor layer 308 has a shape that runs along the top and side surfaces of the conductive layer 312b, the side surface of the insulating layer 310, and the top surface of the conductive layer 312a. The semiconductor layer 308 has a region that overlaps with the conductive layer 312a across the insulating layer 310. Alternatively, the insulating layer 310 can be described as having a region sandwiched between the conductive layer 312a and the semiconductor layer 308. In other words, a portion of the semiconductor layer 308 is disposed inside openings 341 and 343.

[0231] The region of semiconductor layer 308 that contacts conductive layer 312a is used as one of the source region and the drain region, and the region that contacts conductive layer 312b is used as the other of the source region and the drain region. A channel formation region is provided between the source region and the drain region in semiconductor layer 308.

[0232] At least a portion of the insulating layer 306 covers openings 341 and 343. The insulating layer 306 is disposed on the semiconductor layer 308, the conductive layer 312b, and the insulating layer 310. The insulating layer 306 has regions that contact the top and side surfaces of the semiconductor layer 308, the top and side surfaces of the conductive layer 312b, and the top surface of the insulating layer 310. The insulating layer 306 has a shape that extends along the top and side surfaces of the semiconductor layer 308, the top and side surfaces of the conductive layer 312b, and the top surface of the insulating layer 310.

[0233] A conductive layer 304 is disposed on an insulating layer 306 and has a region that contacts the top surface of the insulating layer 306. The conductive layer 304 has a region that overlaps with the semiconductor layer 308 across the insulating layer 306. The conductive layer 304 has a shape that follows the shape of the top surface of the insulating layer 306. Alternatively, the conductive layer 304 may be disposed with openings 341 and 343 embedded within them.

[0234] Transistor 300 is a so-called top-gate transistor that includes a gate electrode above semiconductor layer 308. Furthermore, since the bottom surface of semiconductor layer 308 is in contact with conductive layers 312a and 312b, which serve as source and drain electrodes, it can be considered a TGBC (Top Gate Bottom Contact) type transistor. Additionally, in transistor 300, the heights of the source and drain electrodes relative to the surface of the substrate 302 on which they are formed are different, and drain current flows longitudinally (in the height direction, the depth direction when viewed from above, or the direction perpendicular to the surface of the substrate 302). It can also be said that the channel length direction in transistor 300 includes a longitudinal component. Therefore, transistors like transistor 300 of one embodiment of the present invention can be called longitudinal transistors, vertical transistors, longitudinal channel transistors, or VFETs (Vertical Field Effect Transistors), etc.

[0235] The channel length of transistor 300 can be controlled by the thickness of the insulating layer 310 (specifically, insulating layer 310b) disposed between conductive layers 312a and 312b. Therefore, transistors with channel lengths smaller than the limiting resolution of the exposure apparatus used to manufacture transistors can be manufactured with high precision. Furthermore, characteristic non-uniformity among multiple transistors 300 can be reduced. Therefore, the semiconductor device including transistors 300 operates stably, and reliability can be improved. Moreover, as characteristic non-uniformity is reduced, the circuit design freedom of the semiconductor device is increased, and the operating voltage of the semiconductor device can be reduced. This, in turn, reduces the power consumption of the semiconductor device.

[0236] In transistor 300, a source electrode, a semiconductor layer with a channel forming region, and a drain electrode can be stacked, so the occupied area can be greatly reduced compared to a so-called planar transistor in which the semiconductor layer with the channel forming region is configured as a planar shape.

[0237] Conductive layers 312a, 312b, and 304 can all be used as wiring, and transistor 300 can be disposed in the area where these wirings overlap. That is, in a circuit including transistor 300 and wiring, the area occupied by transistor 300 and wiring can be reduced. Therefore, a smaller semiconductor device can be realized by reducing the area occupied by the circuit.

[0238] Transistor 200 includes conductive layer 204, conductive layer 212a, conductive layer 212b, insulating layer 306, semiconductor layer 208, insulating layer 320, and conductive layer 202. In transistor 200, conductive layer 204 is used as a gate electrode (also referred to as a first gate electrode). A portion of insulating layer 306 is used as a gate insulating layer (also referred to as a first gate insulating layer). Conductive layer 202 is used as a back gate electrode (also referred to as a second gate electrode), and a portion of insulating layer 320 is used as a back gate insulating layer (also referred to as a second gate insulating layer). Conductive layer 212a is used as one of the source electrode and drain electrode, and conductive layer 212b is used as the other of the source electrode and drain electrode. The layers constituting transistor 200 can have a single-layer structure or a stacked structure. Note that transistor 200 may also exclude conductive layer 202 and insulating layer 320.

[0239] In semiconductor layer 208, the entire area between the source electrode and the drain electrode, where the gate insulating layer overlaps with the gate electrode, is used as the channel formation region. Semiconductor layer 208 has a pair of regions 208L that clamp the channel formation region and a pair of regions 208D that are outside the channel formation region.

[0240] Regions 208L and 208D are regions containing impurity elements. One or more of hydrogen, boron, carbon, nitrogen, fluorine, phosphorus, sulfur, arsenic, aluminum, magnesium, silicon, or noble gases can be used as impurity elements. Typical examples of noble gases include helium, neon, argon, krypton, and xenon. One or more of boron, phosphorus, aluminum, magnesium, and silicon are particularly preferred as impurity elements.

[0241] Conductive layers 204, 212a, and 212b are used as masks to supply (also referred to as adding or implanting) impurity elements to semiconductor layer 208. Thus, in semiconductor layer 208, region 208D is formed in a region that does not overlap with any of the conductive layers 204, 212a, 212b, and insulating layer 306, and region 208L is formed in a region that does not overlap with any of the conductive layers 204, 212a, and 212b but overlaps with insulating layer 306.

[0242] The region in semiconductor layer 208 that contacts conductive layer 212a and the region 208D adjacent to it are used as one of the source region and the drain region. The region in semiconductor layer 208 that contacts conductive layer 212b and the region 208D adjacent to it are used as the other of the source region and the drain region.

[0243] An insulating layer 202 is disposed on an insulating layer 310, and an insulating layer 320 is disposed on the conductive layer 202. The insulating layer 320 is disposed such that it covers the top surface and side surface of the conductive layer 202. The insulating layer 320 has a portion that protrudes beyond the end of the conductive layer 202. The end of the insulating layer 320 is in contact with the top surface of the insulating layer 310.

[0244] A semiconductor layer 208 is disposed on the insulating layer 320. The semiconductor layer 208 has a region that overlaps with the conductive layer 202 across the insulating layer 320. The semiconductor layer 208 can be made of the same material as the semiconductor layer 308. Furthermore, the semiconductor layer 208 can be formed using the same process as the semiconductor layer 308. For example, a film forming semiconductor layers 308 and 208 can be formed and processed thereon, thereby forming semiconductor layers 308 and 208.

[0245] An insulating layer 306 is disposed on the semiconductor layer 208. A portion of the insulating layer 306 is used as the gate insulating layer of the transistor 300, and another portion of the insulating layer 306 is used as the gate insulating layer of the transistor 200. The insulating layer 306 has openings 347a and 347b in the region overlapping with the semiconductor layer 208.

[0246] A conductive layer 204, a conductive layer 212a, and a conductive layer 212b are disposed on an insulating layer 306. The conductive layer 204 has a region overlapping the semiconductor layer 208 with the insulating layer 306. Additionally, the conductive layer 204 has a region overlapping the conductive layer 202 with the semiconductor layer 208. The conductive layers 212a and 212b are disposed such that they cover a portion of openings 347a and 347b. The conductive layer 212a is electrically connected to the semiconductor layer 208 through opening 347a, and the conductive layer 212b is electrically connected to the semiconductor layer 208 through opening 347b. The conductive layers 204, 212a, and 212b can be made of the same material as the conductive layer 304. Furthermore, the conductive layers 204, 212a, and 212b can be formed using the same process as the conductive layer 304. For example, by forming a film that becomes conductive layer 304, conductive layer 204, conductive layer 212a and conductive layer 212b and processing the film, conductive layer 304, conductive layer 204, conductive layer 212a and conductive layer 212b can be formed.

[0247] Transistor 200 is a planar transistor in which the semiconductor layer 208 is configured as a plane. Transistor 200 is a so-called top-gate transistor having a gate electrode above the semiconductor layer 208. For example, by adding impurity elements to the semiconductor layer 208 using the conductive layer 204 serving as the gate electrode as a mask, regions 208D serving as source and drain regions can be formed in a self-aligned manner. Transistor 200 can be described as a TGSA (Top Gate Self-Aligned) type transistor.

[0248] The channel length of transistor 200 can be controlled by the length of conductive layer 204. Therefore, the channel length of transistor 200 is a value exceeding the limit resolution of the exposure apparatus used in transistor manufacturing. That is, the channel length of transistor 200 can be larger than that of transistor 300. By increasing the channel length, transistors with high saturation can be achieved.

[0249] Transistor 300 with a short channel length and transistor 200 with a long channel length can be formed on the same substrate using a portion of the same process. For example, by using transistor 300 as a transistor requiring a large on-state current and transistor 200 as a transistor requiring high saturation, a high-performance semiconductor device can be realized.

[0250] For example, when a semiconductor device according to one aspect of the present invention is used in the pixel circuit of a display device, the occupied area of ​​the pixel circuit can be reduced, and a high-definition display device can be realized. Furthermore, for example, when a semiconductor device according to one aspect of the present invention is used in the driving circuit of a display device (e.g., one or both of a gate line driving circuit and a source line driving circuit), the occupied area of ​​the driving circuit can be reduced, thus enabling a display device with a narrow bezel.

[0251] The capacitor 350 includes a conductive layer 312b and a conductive layer 202 serving as a pair of electrodes, and an insulating layer 320. The conductive layer 312b serves as one of the source and drain electrodes of the transistor 300, and also as one of the pairs of electrodes in the capacitor 350. The conductive layer 202 serves as the back gate electrode of the transistor 200, and also as the other of the pairs of electrodes in the capacitor 350. The region of the insulating layer 320 sandwiched between the conductive layers 312b and 202 serves as the dielectric of the capacitor 350. By forming the conductive layers 312b and 202 in different processes, a capacitor 350 comprising these conductive layers as a pair of electrodes can be formed. Furthermore, by forming the conductive layers 312b and 202 in different processes, different materials can be used, thus expanding the range of material choices.

[0252] exist Figure 11AIn the example described, a capacitor 350 composed of a conductive layer 312b, a conductive layer 202, and an insulating layer 320 is used; however, there are no particular limitations on the structure of the capacitor 350. Other structures for the capacitor 350 include, for example, a structure composed of a conductive layer 212a (or conductive layer 212b), a conductive layer 312b, and an insulating layer 306. Alternatively, an example can be given where the capacitor is composed of a conductive layer 202, a conductive layer 312a, and an insulating layer 310. Furthermore, the semiconductor device 10 may not include a capacitor 350. Note that even without a capacitor 350 composed of a conductive layer 312b, a conductive layer 202, and an insulating layer 320, the conductive layers 312b and 202 can be formed using the same process.

[0253] exist Figure 11A In the above, one of the source and drain electrodes of transistor 300 is electrically connected to one of the pair of electrodes of capacitor 350, and the back gate electrode of transistor 200 is electrically connected to the other of the pair of electrodes of capacitor 350. However, there are no particular restrictions on the electrical connection relationship between transistor 300, transistor 200 and capacitor 350.

[0254] An insulating layer 395 is provided to cover transistors 300, 200, and capacitor 350. The insulating layer 395 serves as a protective layer for transistors 300, 200, and capacitor 350.

[0255] There are no particular limitations on the semiconductor materials used for semiconductor layers 308 and 208. For example, semiconductors composed of a single element or compound semiconductors can be used. Examples of semiconductors composed of a single element include silicon and germanium. Examples of compound semiconductors include gallium arsenide and silicon germanium. In addition, organic semiconductors, nitride semiconductors, and oxide semiconductors can be used as compound semiconductors. Note that these semiconductor materials may also contain impurities as dopants.

[0256] There are no particular restrictions on the crystallinity of the semiconductor materials used for semiconductor layer 308 and semiconductor layer 208; amorphous semiconductors, single-crystal semiconductors, or semiconductors with crystallinity other than single crystal (microcrystalline semiconductors, polycrystalline semiconductors, or semiconductors with a portion of crystalline regions) can be used. When using single-crystal semiconductors or crystalline semiconductors, the degradation of transistor characteristics can be suppressed, so they are preferred.

[0257] Both semiconductor layer 308 and semiconductor layer 208 can use silicon. Examples of silicon include monocrystalline silicon, polycrystalline silicon, microcrystalline silicon, and amorphous silicon. For example, low-temperature polycrystalline silicon (LTPS) can be used as polycrystalline silicon. Transistors using amorphous silicon in the channel formation region can be formed on large glass substrates, allowing for low-cost manufacturing. Transistors using polycrystalline silicon in the channel formation region exhibit high field-effect mobility, enabling high-speed operation. Furthermore, transistors using microcrystalline silicon in the channel formation region have higher field-effect mobility than transistors using amorphous silicon, enabling high-speed operation.

[0258] Semiconductor layer 308 and semiconductor layer 208 preferably both contain metal oxides (also known as oxide semiconductors) that exhibit semiconductor properties.

[0259] The band gap of the metal oxides used in semiconductor layer 308 and semiconductor layer 208 is preferably 2.0 eV or more, and more preferably 2.5 eV or more.

[0260] Compared to transistors using amorphous silicon, transistors with an oxide semiconductor channel (hereinafter referred to as OS transistors) exhibit very high field-effect mobility. Furthermore, OS transistors possess extremely low off-state current. At room temperature, the off-state current of an OS transistor with a channel width of 1 μm can reach 1 A (1 × 10⁻⁶). -18 A) Below, 1zA (1×10 -21 A) or below or 1yA (1×10 -24 A) Below. Note that in Si transistors, the off-state current per channel width of 1 μm at room temperature is 1 fA (1 × 10⁻⁶). -15 A) and above and 1pA (1×10) -12 A) Below. Therefore, it can also be said that the off-state current of an OS transistor is about 10 bits smaller than that of a Si transistor. Therefore, for example, when a wiring electrically connected to one of the source and drain terminals of an OS transistor is in a floating state, the charge stored in that wiring can be retained for a long time. Therefore, for example, by using OS transistors to construct memory cells, data written to those memory cells can be stored for a long time.

[0261] Furthermore, even at high temperatures, the off-state current of the OS transistor hardly increases. Specifically, even in environments above room temperature but below 200°C, the off-state current hardly increases. Moreover, even at high temperatures, the on-state current of the OS transistor does not easily decrease. On the other hand, the on-state current of the Si transistor decreases at high temperatures. That is, at high temperatures, the on-state current of the OS transistor is larger than that of the Si transistor. Additionally, even in environments above 125°C but below 150°C, the ratio of on-state current to off-state current of the OS transistor is large, thus enabling good switching operation. Therefore, semiconductor devices using OS transistors operate stably and reliably even at high temperatures.

[0262] In addition, OS transistors have a high breakdown voltage between their source and drain (also known as drain breakdown voltage). Therefore, semiconductor devices using OS transistors operate stably and reliably even when driven at high voltages.

[0263] [Transistor 300]

[0264] use Figures 11A to 11C , Figure 12A and Figure 12B This section describes the detailed structure of transistor 300. Figure 12A and Figure 12B yes Figure 11A and Figure 11B An enlarged view of transistor 300 is shown.

[0265] The insulating layer 310 preferably comprises one or more inorganic insulating films. Materials suitable for use in the inorganic insulating film include, for example, oxides, nitrides, oxynitrides, and oxynitrides. Examples of oxides include silicon oxide, aluminum oxide, magnesium oxide, gallium oxide, germanium oxide, yttrium oxide, zirconium oxide, lanthanum oxide, neodymium oxide, hafnium oxide, tantalum oxide, cerium oxide, gallium zinc oxide, and hafnium aluminate. Examples of nitrides include silicon nitride and aluminum nitride. Examples of oxynitrides include silicon oxynitride, aluminum oxynitride, gallium oxynitride, yttrium oxynitride, and hafnium oxynitride. Examples of oxynitrides include silicon oxynitride and aluminum oxynitride.

[0266] Note that in this specification, oxynitrides refer to materials in which the oxygen content is greater than the nitrogen content. Nitrogen oxides refer to materials in which the nitrogen content is greater than the oxygen content.

[0267] In transistor 300, insulating layer 310 has a region that contacts semiconductor layer 308. When a metal oxide is used as semiconductor layer 308, at least a portion of the region of insulating layer 310 that contacts semiconductor layer 308 preferably contains oxygen in order to improve the interface characteristics between semiconductor layer 308 and insulating layer 310. Specifically, the region of insulating layer 310 that contacts the channel forming region of semiconductor layer 308 preferably contains oxygen. The region of insulating layer 310 that contacts the channel forming region of semiconductor layer 308 can use one or more of oxides and oxynitrides.

[0268] The insulating layer 310 preferably has a laminated structure. Figure 11B Examples are shown where the insulating layer 310 includes an insulating layer 310a, an insulating layer 310b on the insulating layer 310a, and an insulating layer 310c on the insulating layer 310b.

[0269] The region in semiconductor layer 308 that contacts insulating layer 310b is used as a channel formation region. Insulating layer 310b preferably contains oxygen, and preferably uses one or more of the oxides and oxynitrides described above. Specifically, insulating layer 310b can use one or both of silicon oxide and silicon oxynitride.

[0270] More preferably, the insulating layer 310b is a film that releases oxygen upon heating. Because the insulating layer 310b releases oxygen due to the heat applied during the manufacturing process of the transistor 300, oxygen can be supplied to the semiconductor layer 308. By supplying oxygen from the insulating layer 310b to the semiconductor layer 308, particularly to the channel formation region, oxygen vacancies (also known as V0) are repaired. O Oxygen vacancies can be reduced, thus enabling transistors with good electrical properties and high reliability.

[0271] For example, oxygen can be supplied to the insulating layer 310b by heating or plasma treatment in an oxygen-containing atmosphere. Alternatively, oxygen can be supplied by forming an oxide film on the top surface of the insulating layer 310b using sputtering in an oxygen-containing atmosphere. This oxide film can then be removed.

[0272] It is preferable to minimize hydrogen in the semiconductor layer 308, especially in the channel formation region. Hydrogen in the semiconductor layer 308 bonds with oxygen vacancies to form defects (also known as V) caused by hydrogen entering oxygen vacancies. OTherefore, transistor characteristics (e.g., the initial Id-Vg characteristics of the transistor or the Id-Vg characteristics in long-term reliability testing) may deteriorate. Thus, materials with low hydrogen release are preferably used as the material surrounding the semiconductor layer 308, such as the materials used for insulating layers in contact with the semiconductor layer 308 (e.g., insulating layers 310a, 310b, 310c, and 306).

[0273] The insulating layer 310b is preferably formed using deposition methods such as sputtering or plasma-enhanced chemical vapor deposition (PECVD). In particular, by using sputtering and not using hydrogen gas as the deposition gas, a film with extremely low hydrogen content can be achieved. Therefore, the supply of hydrogen to the channel formation region can be suppressed, thereby stabilizing the electrical characteristics of the transistor 300.

[0274] Preferably, the material in the insulating layer 310b diffuses easily. In other words, the diffusion coefficient of the material in the insulating layer 310b is preferably large. Particularly preferred is that oxygen diffuses easily in the insulating layer 310b. That is, the oxygen diffusion coefficient in the insulating layer 310b is preferably large. Oxygen diffuses within the insulating layer 310b and is supplied to the semiconductor layer 308 via the interface between the insulating layer 310b and the semiconductor layer 308. By using the oxygen-diffusive insulating layer 310b, oxygen in the insulating layer 310b can be efficiently supplied to the semiconductor layer 308 (especially the channel formation region).

[0275] The oxygen diffusion coefficient of insulating layer 310b at 350°C is preferably 5 × 10⁻⁶. -12 cm 2 / sec or higher, more preferably 1×10 -11 cm 2 / sec or higher, further preferably 5×10 -11 cm 2 / sec or higher, and further preferred to be 1×10 -10 cm 2 The diffusion coefficient is above / sec. This allows for efficient supply of oxygen from the insulating layer 310b to the semiconductor layer 308. A higher diffusion coefficient is better, therefore no specific upper limit is set. The diffusion coefficient can be calculated, for example, using thermal desorption spectroscopy (TDS). Alternatively, secondary ion mass spectrometry (SIMS) can also be used.

[0276] Here, by using a material with high conductivity in the semiconductor layer 308, a transistor with a large on-state current can be realized. However, when using a material with high conductivity, oxygen vacancies are easily formed. When there are more oxygen vacancies in the channel formation region, the threshold voltage of the transistor sometimes drifts, and the drain current (hereinafter also referred to as the cutoff current) flowing through when the gate voltage is 0V increases. For example, in an n-channel transistor, the cutoff current sometimes increases when the threshold voltage drifts negatively. By providing an insulating layer 310b, oxygen is supplied at least to the region in the semiconductor layer 308 that is in contact with the insulating layer 310b, i.e., the channel formation region, thus reducing the number of oxygen vacancies in the channel formation region. As a result, threshold voltage drift can be suppressed, and a transistor with a small cutoff current and a large on-state current can be realized. Thus, a low-power and high-performance semiconductor device can be realized.

[0277] In semiconductor layer 308, the region in contact with conductive layer 312a is used as one of the source and drain regions of transistor 300, and the region in contact with conductive layer 312b is used as the other. The source and drain regions are regions with lower resistance than the channel formation region. The source and drain regions can also be described as regions with higher carrier concentration or higher oxygen vacancy density compared to the channel formation region.

[0278] An insulating layer 310a is disposed between an insulating layer 310b and a conductive layer 312a. An insulating layer 310c is disposed between an insulating layer 310b and a conductive layer 312b. Preferably, the insulating layers 310a and 310c release small amounts of impurities (e.g., hydrogen and water) and are not easily permeable by impurities. This suppresses the diffusion of impurities from the insulating layers 310a and 310c into the channel formation region. Consequently, a transistor exhibiting good electrical characteristics and high reliability can be realized.

[0279] Both insulating layers 310a and 310c are preferably made of films that are not easily permeable by oxygen. This prevents oxygen in insulating layer 310b from diffusing through insulating layer 310a to conductive layer 312a. Similarly, it prevents oxygen in insulating layer 310b from diffusing through insulating layer 310c to conductive layer 312b. This prevents the resistance of conductive layers 312a and 312b from increasing. Simultaneously, it prevents oxygen in insulating layer 310b from diffusing to both the insulating layer 310a and insulating layer 310c sides. Therefore, the amount of oxygen supplied from insulating layer 310b to the channel forming region increases, thereby reducing oxygen vacancies and V in the channel forming region. O H.

[0280] By using a membrane that makes it difficult for oxygen to diffuse into each of insulating layers 310a and 310c, oxygen can be effectively supplied from insulating layer 310b to the channel forming region. Note that either or both of insulating layers 310a and 310c may not be provided.

[0281] Both insulating layers 310a and 310c preferably contain nitrogen, and preferably use one or more of the aforementioned nitrides and oxynitrides. For example, both insulating layers 310a and 310c can be made of silicon nitride or silicon oxynitride. Furthermore, one or both of insulating layers 310a and 310c can be made of oxides and oxynitrides. For example, both insulating layers 310a and 310c can be made of aluminum oxide. Note that insulating layer 310a can be made of the same material as insulating layer 310c, or it can be made of a different material.

[0282] Note that in this specification, etc., different materials refer to materials whose constituent elements are partially or wholly different, or materials whose constituent elements are the same but whose composition is different.

[0283] The thickness T310a of the insulating layer 310a can be, for example, 3nm or more, 5nm or more, 10nm or more, 20nm or more, 50nm or more, or 70nm or more and less than 1μm, or less than 500nm, 400nm or less, 300nm or less, 200nm or less, 150nm or less, or 120nm or less. Figure 12B As shown, the thickness T310a can be set as the shortest distance between the surface of the insulating layer 310a (here, the top surface of the conductive layer 312a) and the bottom surface of the insulating layer 310b in cross-section.

[0284] When the thickness T310a of the insulating layer 310a is large, the amount of impurities released from the insulating layer 310a may increase, leading to an increase in the amount of impurities diffusing into the channel formation region. On the other hand, when the thickness T310a is small, oxygen in the insulating layer 310b may diffuse through the insulating layer 310a to the conductive layer 312a side, reducing the amount of oxygen supplied to the channel formation region. By setting the thickness T310a within the above range, the oxygen vacancies and V in the channel formation region can be reduced. O H. In addition, it can suppress the oxidation of the conductive layer 312a caused by oxygen in the insulating layer 310b, which would increase the resistance of the conductive layer 312a.

[0285] The thickness T310c of the insulating layer 310c can be, for example, 3nm or more, 5nm or more, 10nm or more, 15nm or more, or 20nm or more and less than 1μm, less than 500nm, less than 300nm, less than 200nm, less than 150nm, less than 120nm, or less than 100nm. For example... Figure 12BAs shown, in cross-section, the thickness T310c can be the shortest distance between the surface of the insulating layer 310c (here, the top surface of the insulating layer 310b) and the bottom surface of the conductive layer 312b.

[0286] When the thickness T310c of the insulating layer 310c is large, the amount of impurities released from the insulating layer 310c may increase, leading to an increase in the amount of impurities diffusing into the channel formation region. On the other hand, when the thickness T310c is small, oxygen in the insulating layer 310b may diffuse through the insulating layer 310c to the conductive layer 312b side, reducing the amount of oxygen supplied to the channel formation region. By setting the thickness T310c within the above range, the oxygen vacancies and V in the channel formation region can be reduced. O H. In addition, it can suppress the oxidation of the conductive layer 312b caused by oxygen in the insulating layer 310b, which would increase the resistance of the conductive layer 312b.

[0287] At least one of the regions of semiconductor layer 308 that contact insulating layer 310a and insulating layer 310c can also be regions having a lower resistance than the channel formation region (hereinafter also referred to as low-resistance regions). This region can also be described as a region with a higher carrier concentration or a higher oxygen vacancy density compared to the channel formation region. When a material that releases impurities (e.g., water and hydrogen) is used in insulating layer 310a, the region of semiconductor layer 308 that contacts insulating layer 310a can be used as a low-resistance region. Semiconductor layer 308 can also have a low-resistance region between the region contacting conductive layer 312a (one of the source region and drain region) and the channel formation region. Similarly, when a material that releases impurities is used in insulating layer 310c, the region of semiconductor layer 308 that contacts insulating layer 310c can be used as a low-resistance region. Semiconductor layer 308 can also have a low-resistance region between the region contacting conductive layer 312b (the other of the source region and drain region) and the channel formation region. The low-resistance region can also be used as a buffer region to mitigate the drain electric field. Note that these low-resistance regions can also be used as source or drain regions.

[0288] By providing a low-resistance region between the drain region and the channel formation region, a high electric field is less likely to be generated near the drain region, thus suppressing the generation of hot carriers and preventing transistor degradation. For example, when conductive layer 312a is used as the drain electrode and conductive layer 312b is used as the source electrode, by using the region of semiconductor layer 308 in contact with insulating layer 310a as a low-resistance region, a high electric field is less likely to be generated near the drain region, suppressing the generation of hot carriers and thus preventing transistor degradation. When conductive layer 312a is used as the source electrode and conductive layer 312b is used as the drain electrode, by using the region of semiconductor layer 308 in contact with insulating layer 310c as a low-resistance region, a high electric field is less likely to be generated near the drain region, suppressing the generation of hot carriers and thus preventing transistor degradation.

[0289] As described above, when the amount of impurities released by insulating layers 310a and 310c is excessive, the impurities may diffuse into the channel forming region. Even when using materials that release impurities in insulating layers 310a and 310c, the amount of released impurities is preferably small.

[0290] Note that insulating layer 310 preferably includes at least insulating layer 310b. For example, it may not include one or both of insulating layers 310a and 310c. In addition, insulating layer 310 may have a stacked structure of two or four or more layers, or it may have a single-layer structure.

[0291] There are no restrictions on the shape of the top surface of openings 341 and 343. For example, they can be circular, elliptical, triangular, quadrilateral (including rectangles, rhombuses, and squares), pentagonal, or other polygons with rounded corners. The polygon can also be a concave polygon (a polygon with at least one interior angle exceeding 180 degrees) or a convex polygon (a polygon with all interior angles less than 180 degrees). Figure 11A As shown, the top surface shape of openings 341 and 343 is preferably circular. The circular shape of the top surface of the openings improves the machining accuracy during opening formation and allows for the formation of fine openings. Note that in this specification, the circular shape is not limited to a perfect circle.

[0292] By forming openings 341 and 343 with a top surface shape that is circular or approximately circular, the semiconductor layer 308, the insulating layer 306, and the conductive layer 304 are arranged in a concentric circle. As a result, the distance between the conductive layer 304 and the semiconductor layer 308 is approximately uniform, so a gate electric field can be applied to the semiconductor layer 308 approximately uniformly.

[0293] In this specification, the top surface shape of opening 341 refers to the shape of the top surface end of the insulating layer 310 on the side of opening 341. The top surface shape of opening 343 refers to the shape of the bottom surface end of the conductive layer 312b on the side of opening 343.

[0294] like Figure 11A As shown, the top surface shape of opening 341 and the top surface shape of opening 343 can be the same. In this case, as... Figure 11B and Figure 11C As shown, the height of the bottom end of the conductive layer 312b on the side of the opening 343 is preferably the same as the height of the top end of the insulating layer 310 on the side of the opening 341. The bottom surface of the conductive layer 312b refers to the surface on the side of the insulating layer 310. The top surface of the insulating layer 310 refers to the surface on the side of the conductive layer 312b.

[0295] Furthermore, the top surface shape of opening 341 may not be the same as that of opening 343. In addition, when the top surface shapes of opening 341 and opening 343 are circular, opening 341 and opening 343 may or may not be concentric circles.

[0296] Reference Figure 12A and Figure 12B Explain the channel length and channel width of transistor 300.

[0297] exist Figure 12B The channel length L300 of transistor 300 is indicated by a dashed double arrow. The channel length L300 of transistor 300 is equivalent to the length of the side surface of the insulating layer 310b on the side of the opening 341 when viewed in cross-section. In other words, the channel length L300 is determined by the thickness T310b of the insulating layer 310b and the angle θ310 formed by the side surface of the insulating layer 310b on the side of the opening 341 and the surface of the insulating layer 310b to which it is formed (here, the top surface of the insulating layer 310a). Therefore, by setting the channel length L300 to a value smaller than the limiting resolution of the exposure apparatus, miniature transistors can be realized. Specifically, transistors with extremely small channel lengths that are difficult to achieve in the exposure apparatuses used in the mass production of existing flat panel displays (e.g., with a minimum linewidth of about 2 μm or 1.5 μm) can be realized. Furthermore, transistors with channel lengths less than 10 nm can be realized without using the very expensive exposure apparatuses used in the most advanced LSI technology.

[0298] The channel length L300 can be, for example, greater than 1 nm, greater than 5 nm, greater than 7 nm, or greater than 10 nm but less than 3 μm, less than 2.5 μm, less than 2 μm, less than 1.5 μm, less than 1.2 μm, less than 1 μm, less than 500 nm, less than 300 nm, less than 200 nm, less than 100 nm, less than 60 nm, less than 50 nm, less than 40 nm, less than 30 nm, less than 20 nm, or less than 10 nm. For example, the channel length L300 can be set to greater than 100 nm and less than 1 μm.

[0299] By shortening the channel length L300, the on-state current of the transistor 300 can be increased. Using the transistor 300, circuits capable of high-speed operation can be manufactured. Furthermore, the circuit's footprint can be reduced. Therefore, a miniaturized semiconductor device can be realized. For example, in the case of a semiconductor device according to one aspect of the present invention used in a large display device or a high-definition display device, the signal delay of each wiring can be reduced even when the number of wirings increases, thereby suppressing display unevenness. In addition, since the circuit's footprint can be reduced, the bezel of the display device can be reduced.

[0300] The channel length L300 can be controlled by adjusting the thickness T310b of the insulating layer 310b and the angle θ310. Figure 12B In the diagram, the thickness T310b of the insulating layer 310b is indicated by a double-headed dotted line.

[0301] The thickness T310b of the insulating layer 310b can be, for example, greater than 1 nm, greater than 5 nm, greater than 7 nm, or greater than 10 nm and less than 3 μm, less than 2.5 μm, less than 2 μm, less than 1.5 μm, less than 1.2 μm, less than 1 μm, less than 500 nm, less than 300 nm, less than 200 nm, less than 100 nm, less than 60 nm, less than 50 nm, less than 40 nm, less than 30 nm, less than 20 nm, or less than 10 nm.

[0302] The side of the insulating layer 310 with opening 341 is preferably vertical or conical. The angle θ310 is preferably 90 degrees or less. By reducing the angle θ310, the coverage of the layer (e.g., semiconductor layer 308) formed on the insulating layer 310 can be improved. In addition, the smaller the angle θ310, the larger the channel length L300 can be, and the larger the angle θ310 (close to 90 degrees), the smaller the channel length L300 can be.

[0303] Angle θ310 can be, for example, greater than 30 degrees, greater than 35 degrees, greater than 40 degrees, greater than 45 degrees, greater than 50 degrees, greater than 55 degrees, greater than 60 degrees, greater than 65 degrees, or greater than 70 degrees and less than 90 degrees, less than 85 degrees, or less than 80 degrees. Angle θ310 can also be less than 75 degrees, less than 70 degrees, less than 65 degrees, or less than 60 degrees.

[0304] Note that in Figure 12B In the cross-section, the shape of the side surface of the insulating layer 310 on the side of the opening 341 is shown as a straight line; however, one aspect of the invention is not limited to this. In the cross-section, the shape of the side surface of the insulating layer 310 on the side of the opening 341 can be curved, or it can have both a region with a straight line shape and a region with a curved shape.

[0305] Here, the conductive layer 312b is preferably not disposed inside the opening 341. Specifically, the conductive layer 312b preferably does not have a region that contacts the side surface of the insulating layer 310 on the side of the opening 341. When the conductive layer 312b is also disposed inside the opening 341, the channel length L300 of the transistor 300 is shorter than the length of the side surface of the insulating layer 310b, so sometimes controlling the channel length L300 becomes difficult. Therefore, it is preferable that the top surface shape of the opening 343 is consistent with the top surface shape of the opening 341, or that the opening 343 covers the opening 341 when viewed from above.

[0306] exist Figure 12A and Figure 12B The width D341 of the opening is represented by a double-dotted line and a double-headed arrow. Figure 12A An example is shown where the top surface of opening 341 is circular. In this case, the width D341 is equivalent to the diameter of the circle, and the channel width W300 of transistor 300 is equivalent to the circumference of the circle. That is, the channel width W300 is π × D341. Thus, when the top surface of opening 341 is circular, a transistor with a smaller channel width W300 can be realized compared to other shapes.

[0307] In addition, if the top surface shape of the opening 341 is not circular (e.g., approximately circular or a quadrilateral with rounded corners), the maximum width of the top surface shape can be, for example, the width D341.

[0308] The width D341 of the opening 341 sometimes varies in the depth direction. For example, the width D341 of the opening 341 can be the average of the diameters of the highest, lowest, and midpoints of the insulating layer 310b (or insulating layer 310) in cross-section. Alternatively, any diameter among the diameters of the highest, lowest, and midpoints of the insulating layer 310b (or insulating layer 310) in cross-section can be used as the diameter of the opening 341.

[0309] When the aperture 341 is formed by photolithography, the width D341 of the aperture 341 is above the limit resolution of the exposure apparatus. When using an exposure apparatus used in the mass production of existing flat panel displays, the width D341 can be, for example, 200 nm or more, 300 nm or more, 400 nm or more, or 500 nm or more and less than 5 μm, 4.5 μm or less, 4 μm or less, 3.5 μm or less, 3 μm or less, 2.5 μm or less, 2 μm or less, 1.5 μm or less, or 1 μm or less. Alternatively, when using a very expensive exposure apparatus used in cutting-edge LSI technology, the width D341 can be, for example, 5 nm or more, 10 nm or more, or 20 nm or more and less than 100 nm, 60 nm or less, 50 nm or less, 40 nm or less, or 30 nm or less.

[0310] The channel length L300 of transistor 300 is preferably at least less than the channel width W300 of transistor 300. The channel length L300 of transistor 300 is at least 0.1 times and less than 0.99 times the channel width W300 of transistor 300, preferably at least 0.5 times and less than 0.8 times. By adopting this structure, transistors with good electrical characteristics and high reliability can be realized.

[0311] When shortening the channel length L300 of the transistor 300, insulating layers 310a and 310c preferably use materials that release less hydrogen from themselves. When using materials that release a small amount of hydrogen for insulating layers 310a and 310c, their thickness is preferably small. For example, when the channel length L300 is 100 nm or less, the thicknesses T310a and T310c of insulating layers 310a and 310c are preferably 1 nm or more, 3 nm or more, or 5 nm or more and 50 nm or less, 40 nm or less, 30 nm or less, 20 nm or less, 15 nm or less, or 10 nm or less. This reduces the amount of impurities diffusing into the channel formation region, enabling transistors that exhibit good electrical characteristics and high reliability even with a short channel length L300.

[0312] Note that this description uses the structure where the region in semiconductor layer 308 that contacts insulating layer 310b is used as a channel forming region as an example; however, the invention is not limited to this. The region in semiconductor layer 308 that contacts insulating layer 310a can also be used as a channel forming region. Similarly, the region that contacts insulating layer 310c can also be used as a channel forming region.

[0313] Figure 11B Examples are shown where the semiconductor layer 308, insulating layer 306, and conductive layer 304 cover openings 341 and 343 in transistor 300, but one aspect of the invention is not limited thereto. Alternatively, the structure may have a step formed by the insulating layer 310 and conductive layer 312a, along which the semiconductor layer 308, insulating layer 306, and conductive layer 304 are disposed.

[0314] [Transistor 200]

[0315] Next, use Figures 13A to 13C This describes the detailed structure of transistor 200. Figures 13A to 13C yes Figures 11A to 11C An enlarged view of transistor 200 is shown.

[0316] The channel length of transistor 200 is the length of the overlapping region between a pair of regions 208D, where the semiconductor layer 208 and the conductive layer 204 overlap. Figure 13A and Figure 13BIn the diagram, the channel length L200 of transistor 200 is represented by a dashed double arrow. The channel length L200 of transistor 200 is determined by the length of the conductive layer 204 in the channel length direction and is a value above the limit resolution of the exposure apparatus used in transistor manufacturing. For example, the channel length L200 can be 1.5 μm or more. By increasing the channel length, transistors with high saturation can be achieved.

[0317] The conductive layer 202, which serves as the back gate electrode of the transistor 200, preferably extends beyond the end of the channel forming region. Specifically, the conductive layer 202 preferably has a portion that protrudes beyond the end of the conductive layer 204 in the channel length direction.

[0318] In this specification, for ease of explanation, the portion of the semiconductor layer 208 that overlaps with the conductive layer 204 is sometimes referred to as the channel formation region. However, in reality, the channel is sometimes also formed in the portion that does not overlap with the conductive layer 204 but overlaps with the conductive layer 202.

[0319] The channel width of transistor 200 is the width of the overlapping region of semiconductor layer 208 and conductive layer 204 in a direction orthogonal to the channel length direction. Figure 13A and Figure 13C In the diagram, the channel width W200 of transistor 200 is represented by a dotted-dash double arrow.

[0320] As described above, the channel length L300 of transistor 300 can be set to a value smaller than the limit resolution of the exposure apparatus, while the channel length L200 of transistor 200 can be set to a value greater than or equal to the limit resolution of the exposure apparatus. For example, by using transistor 300 as a transistor requiring a large on-state current and transistor 200 as a transistor requiring high saturation, a high-performance semiconductor device 10 utilizing the advantages of each transistor can be realized. Furthermore, transistors 300 and 200 can be formed using a portion of the same process. Specifically, semiconductor layer 308 and semiconductor layer 208 can be formed using the same process. A portion of insulating layer 306 is used as the gate insulating layer of transistor 300, and another portion of insulating layer 306 is used as the gate insulating layer of transistor 200. Conductive layers 304, 204, 212a, and 212b can be formed using the same process. Therefore, the productivity of semiconductor device 10 can be improved and manufacturing costs reduced.

[0321] like Figure 13A and Figure 13C As shown, preferably, the conductive layers 204 and 202 protrude to the outer side of the end of the semiconductor layer 208 in the channel width direction of the transistor 200. At this time, as... Figure 13CAs shown, the entire channel width of semiconductor layer 208 is covered by conductive layers 204 and 202, separated by insulating layers 306 and 320. With this structure, an electric field generated by a pair of gate electrodes can be used to surround semiconductor layer 208.

[0322] Furthermore, transistor 200 may also omit conductive layer 202 and insulating layer 320. That is, it may also omit back gate electrode.

[0323] Figure 14 This is a cross-sectional view of transistor 200A, a variant of transistor 200. The difference between transistor 200A and transistor 200 is that transistor 200A does not include the conductive layer 202 and the insulating layer 320. This, for example, can reduce manufacturing costs.

[0324] exist Figure 13A and Figure 13C The diagram shows that the conductive layer 204 (i.e., the gate electrode) and the conductive layer 202 (i.e., the back gate electrode) are not electrically connected. Alternatively, a constant potential can be supplied to one of the gate electrode and the back gate electrode, and a signal for driving the transistor 200 can be supplied to the other. In this case, when driving the transistor 200 using the signal supplied to the other of the gate electrode and the back gate electrode, the threshold voltage can be controlled using the potential supplied to one of the gate electrode and the back gate electrode.

[0325] Conductive layers 204 and 202 can also be electrically connected to each other. By supplying the same potential to the gate electrode and the back gate electrode, an electric field for inducing the channel can be effectively applied to the semiconductor layer 208, thereby increasing the on-state current of the transistor 200. Therefore, a miniaturized transistor 200 can be realized. For example, an opening leading to the conductive layer 202 can be formed in the insulating layers 306 and 320, and the conductive layer 204 can be formed in a manner that covers the opening.

[0326] The conductive layer 202 can also be electrically connected to the conductive layer 212a or the conductive layer 212b (i.e., the source electrode or the drain electrode). By supplying the same potential to the back gate electrode and the source electrode, the back gate voltage can be made 0V. Alternatively, by supplying the same potential to one of the back gate electrode and the drain electrode, the back gate voltage can be made the same as the drain voltage. For example, an opening leading to the conductive layer 202 can be provided in the insulating layer 320, and the conductive layer 212a or the conductive layer 212b can be formed in a manner that covers the opening.

[0327] The insulating layer 320, which is disposed in contact with the top and side surfaces of the conductive layer 202, can be made of a material that can be used for the insulating layer 310.

[0328] The insulating layer 320 preferably has a laminated structure. Figure 13BThe diagram shows a structure in which the insulating layer 320 has a laminated structure of insulating layer 320a and insulating layer 320b on insulating layer 320a. Both insulating layer 320a and insulating layer 320b can be made of materials that can be used in insulating layer 310.

[0329] More preferably, an oxygen-releasing film is used in the insulating layer 320b, which contacts the channel formation region of the semiconductor layer 208. Since oxygen is released from the insulating layer 320b due to the heat applied during the manufacturing process of the transistor 200, oxygen can be supplied to the semiconductor layer 208, particularly to the channel formation region of the semiconductor layer 208. Oxygen diffuses within the insulating layer 320b and is supplied to the semiconductor layer 208 via the interface between the insulating layer 320b and the semiconductor layer 208. By supplying oxygen from the insulating layer 320b to the semiconductor layer 208, particularly to the channel formation region, oxygen vacancies are repaired, and oxygen vacancies can be reduced. Thus, a transistor exhibiting good electrical characteristics and high reliability can be realized.

[0330] The oxygen diffusion coefficient of insulating layer 320b at 350°C is preferably 1×10⁻⁶. -12 cm 2 / sec or higher, more preferably 5×10 -12 cm 2 / sec or more.

[0331] The insulating layer 320b can be made of a material that is also suitable for the insulating layer 310b. The insulating layer 320b preferably contains oxygen and can use one or more of oxides and oxynitrides. Specifically, the insulating layer 320b can be, for example, silicon oxide or silicon oxynitride.

[0332] Here, compared to transistor 300 with a short channel length, in transistor 200 with a long channel length, the oxygen vacancies and V in the channel formation region are... O The effect of hydrogen on electrical properties is minimal. Therefore, the amount of oxygen supplied from insulating layer 320b to semiconductor layer 208 can be less than the amount of oxygen supplied from insulating layer 310b to semiconductor layer 308. The amount of oxygen released from insulating layer 320b can also be less than the amount of oxygen released from insulating layer 310b.

[0333] The diffusion coefficient of the material in insulating layer 310b is preferably larger than that of the material in insulating layer 320b. In particular, the oxygen diffusion coefficient in insulating layer 310b is preferably larger than that in insulating layer 320b. Thus, the transistor 300 with a short channel length can also be a transistor exhibiting good electrical characteristics and high reliability.

[0334] The insulating layer 320a in contact with the conductive layer 202 is preferably made of a material in which the metal elements contained in the conductive layer 202 do not easily diffuse. This can suppress the diffusion of the metal elements contained in the conductive layer 202 through the insulating layer 320 into the channel formation region of the semiconductor layer 208.

[0335] Insulating layer 320a may use materials suitable for insulating layers 310a and 310c. Insulating layer 320a preferably contains nitrogen and may use one or more of nitrides and oxynitrides. Specifically, insulating layer 320a may use, for example, silicon nitride. Alternatively, insulating layer 320a may also use one or more of oxides and oxynitrides. Insulating layer 320a may use, for example, aluminum oxide. Note that insulating layers 320a, 310a, and 310c may use the same materials or different materials.

[0336] Preferably, the insulating layer 320a releases few impurities (e.g., water and hydrogen). This suppresses the diffusion of impurities contained in the insulating layer 320a through the insulating layer 320b into the channel formation region of the semiconductor layer 208, enabling the realization of transistors exhibiting good electrical characteristics and high reliability.

[0337] Note that the insulating layer 320 is shown here as having a two-layer stacked structure, but the invention is not limited to this. The insulating layer 320 may have a stacked structure of three or more layers, or it may have a single-layer structure.

[0338] The insulating layer 320 is preferably disposed in the region that is in contact with at least the channel formation region of the semiconductor layer 208 and is disposed in such a manner that it covers the top and side surfaces of the conductive layer 202. Figure 13B In this configuration, the semiconductor layer 208 has a portion that protrudes beyond the end of the insulating layer 320. The semiconductor layer 208 has a region that contacts the side surface of the insulating layer 320. A portion of the end of the semiconductor layer 208 contacts the top surface of the insulating layer 320, and another portion contacts the top surface of the insulating layer 310. Alternatively, a portion of the bottom surface of the semiconductor layer 208 contacts the top surface of the insulating layer 320, and another portion contacts the top surface of the insulating layer 310. Alternatively, the insulating layer 320 may be disposed in the region where the semiconductor layer 208 is disposed, such that the entire bottom surface of the semiconductor layer 208 contacts the top surface of the insulating layer 320.

[0339] Notice, Figure 13BExamples are shown where the thickness of the semiconductor layer 208 is uniform at any location, but one aspect of the invention is not limited thereto. The thickness of the semiconductor layer 208 may also differ between regions that overlap with and do not overlap with the insulating layer 306. For example, when forming openings 347a and 347b, sometimes a portion of the semiconductor layer 208 is removed, and the thickness of the region of the semiconductor layer 208 that does not overlap with the insulating layer 306 is smaller than the thickness of the region that overlaps with the insulating layer 306. Alternatively, the thickness of the semiconductor layer 208 may also differ between regions that overlap with any of the insulating layer 306, conductive layers 212a, and conductive layers 212b, and regions that do not overlap with any of them. For example, when forming conductive layers 212a and 212b, sometimes a portion of the semiconductor layer 208 is removed, and the thickness of the region of the semiconductor layer 208 that does not overlap with any of the insulating layer 306, conductive layers 212a, and conductive layers 212b is smaller than the thickness of the region that overlaps with any of them. Alternatively, the thickness of the semiconductor layer 208 can vary between the region overlapping with the insulating layer 306, the region overlapping with any one of the insulating layer 306, conductive layers 212a and 212b, and the region not overlapping with any one of them.

[0340] In semiconductor layer 208, region 208D is a region with lower resistance than the channel formation region. Region 208D can be described as a region with higher carrier concentration, higher oxygen vacancy density, or higher impurity concentration compared to the channel formation region.

[0341] Region 208L is a region with equal or lower resistivity compared to the channel formation region. Region 208L can also be described as a region with equal or higher carrier concentration, oxygen vacancy density, or impurity concentration compared to the channel formation region. Furthermore, region 208L is a region with equal or higher resistivity compared to region 208D. Region 208L can also be described as a region with equal or lower carrier concentration, oxygen vacancy density, or impurity concentration compared to region 208D.

[0342] Region 208L is used as a buffer region to mitigate the drain electric field. Since region 208L does not overlap with conductive layer 204, almost no channel is formed when a gate voltage is supplied to conductive layer 204. The carrier concentration in region 208L is preferably higher than that in the channel formation region. This allows region 208L to be used as an LDD (Lightly Doped Drain) region. By providing region 208L as an LDD region between the channel formation region and region 208D, a transistor 200 with a high drain breakdown voltage can be realized.

[0343] Furthermore, the carrier concentration of the semiconductor layer 208 preferably has the following distribution: lowest in the channel formation region, and increasing sequentially in the order of region 208L and region 208D. By providing region 208L between the channel formation region and region 208D, for example, even if impurities such as hydrogen diffuse from region 208D during the manufacturing process, the carrier concentration in the channel formation region can be kept extremely low.

[0344] Note that the carrier concentration in region 208L can also be non-uniform, sometimes exhibiting a gradient that decreases from the region 208D side towards the channel formation region. For example, there can also be a gradient in region 208L where one or both of the hydrogen concentration and oxygen vacancy concentration decrease from the region 208D side towards the channel formation region.

[0345] Alternatively, when adding impurity elements to semiconductor layer 208 to form regions 208L and 208D, conductive layer 304 can be used as a mask and the impurity elements can be supplied to semiconductor layer 308 through insulating layer 306. Thus, region 308L is formed in a region of semiconductor layer 308 that does not overlap with conductive layer 304. Note that in transistor 300, the region of semiconductor layer 308 that contacts conductive layer 312b is used as a source region or drain region. Region 308L is formed in a portion of this source region or drain region. Note that the impurity element concentration in region 308L can also be different from the impurity element concentration in region 208L. Alternatively, region 308L may not be formed. For example, when conductive layer 304 extends and covers the end of semiconductor layer 308, the entire semiconductor layer 308 is covered by conductive layer 304, therefore impurity elements are not supplied to semiconductor layer 308 and region 308L is not formed.

[0346] like Figure 13A and Figure 13B As shown, a portion of the ends of conductive layers 212a and 212b is preferably located inside openings 347a and 347b. In other words, in openings 347a and 347b, a portion of the ends of conductive layers 212a and 212b is preferably in contact with semiconductor layer 208. Thus, the region in contact with conductive layer 212a can be adjacent to one of a pair of regions 208D, and similarly, the region in contact with conductive layer 212b can be adjacent to the other of the pair of regions 208D.

[0347] Note that there are no particular restrictions on the top surface shape of openings 347a and 347b. The top surface shape of openings 347a and 347b can be any shape that can be used for openings 341 and 343. Figure 13AThe top surface shapes of openings 347a and 347b are shown to be different from those of openings 341 and 343, i.e., they are quadrangular structures with rounded corners. However, one aspect of the invention is not limited to this. The top surface shapes of openings 347a and 347b may also be the same as those of openings 341 and 343.

[0348] Additionally, while conductive layers 212a and 212b are shown here formed using the same process as conductive layer 204, this is not an exclusive embodiment of the invention. Conductive layers 212a and 212b can also be formed using a different process than conductive layer 204. For example, conductive layers 304 and 204 can be formed on insulating layer 306, and conductive layer 204 can be used as a mask to supply impurity elements to semiconductor layer 208, thereby forming source and drain regions. An insulating layer 395 can be formed on conductive layers 304 and 204, and openings leading to the source and drain regions can be formed in insulating layers 306 and 395, with conductive layers 212a and 212b formed to cover these openings.

[0349] [Semiconductor layer 308 and semiconductor layer 208]

[0350] Specifically, the metal oxides that can be used in semiconductor layer 308 and semiconductor layer 208 will be described. Examples of metal oxides include indium oxide, gallium oxide, and zinc oxide. The metal oxide preferably contains at least indium or zinc. Furthermore, the metal oxide preferably contains two or three elements selected from indium, element M, and zinc. Element M is a metallic or half-metallic element with a high bond energy with oxygen, for example, a metallic or half-metallic element with a higher bond energy with oxygen than indium. Specifically, 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 one or more of gallium and tin. Note that in this specification, etc., metallic elements and half-metallic elements are sometimes collectively referred to as "metallic elements", and the "metallic elements" described in this specification, etc., sometimes include half-metallic elements.

[0351] Semiconductor layer 308 and semiconductor layer 208 can, for example, use indium oxide (In oxide), indium zinc oxide (In-Zn oxide), indium tin oxide (also denoted as In-Sn oxide or ITO), indium titanium oxide (In-Ti oxide), indium gallium oxide (In-Ga oxide), indium tungsten oxide (also denoted as In-W oxide or IWO), indium gallium aluminum oxide (In-Ga-Al oxide), indium gallium tin oxide (In-Ga-Sn oxide), gallium zinc oxide (also denoted as Ga-Zn oxide or GZO), aluminum zinc oxide (also denoted as Al). Indium aluminum zinc oxide (also known as In-Al-Zn oxide or IAZO), indium tin zinc oxide (also known as In-Sn-Zn oxide or ITZO (registered trademark)), indium titanium zinc oxide (In-Ti-Zn oxide), indium gallium zinc oxide (also known as In-Ga-Zn oxide or IGZO), indium gallium tin zinc oxide (In-Ga-Sn-Zn oxide, also known as IGZTO), indium gallium aluminum zinc oxide (also known as In-Ga-Al-Zn oxide, IGAZO, IGZAO, or IAGZO), etc., can be used. Alternatively, silicon-containing materials such as indium tin oxide (also known as ITSO), gallium tin oxide (Ga-Sn oxide), and aluminum tin oxide (Al-Sn oxide) can be used. Furthermore, materials that do not contain Zn, such as indium oxide, have high affinity for Si processes and are therefore preferred. On the other hand, materials containing Zn can improve crystallinity and are therefore preferred.

[0352] Increasing the proportion of indium atoms in a metal oxide relative to the sum of the atomic numbers of all metal elements can improve the field-effect mobility of a transistor. Furthermore, it allows for the realization of transistors with high on-state currents.

[0353] Note that metal oxides can also replace indium or contain one or more metals with high period numbers in addition to indium. There is a tendency that the greater the orbital overlap of the metal element, the greater the carrier conduction in the metal oxide. Therefore, by including metals with high period numbers, the field-effect mobility of transistors can sometimes be improved. Examples of metals with high period numbers include those belonging to the 5th period and those belonging to the 6th period. Specifically, examples of such metals include yttrium, zirconium, silver, cadmium, tin, antimony, barium, lead, bismuth, lanthanum, cerium, praseodymium, neodymium, promethium, samarium, and europium. Note that lanthanum, cerium, praseodymium, neodymium, promethium, samarium, and europium are called light rare earth elements.

[0354] Metal oxides can also contain one or more non-metallic elements. When metal oxides contain non-metallic elements, the field-effect mobility of transistors can sometimes be improved due to increased carrier concentration or narrower band gap. Examples of non-metallic elements include carbon, nitrogen, phosphorus, sulfur, selenium, fluorine, chlorine, bromine, and hydrogen.

[0355] When the proportion of zinc atoms in a metal oxide relative to the sum of the atomic numbers of all metal elements is increased, the metal oxide exhibits high crystallinity, which suppresses the diffusion of impurities within the metal oxide. Therefore, variations in the electrical characteristics of the transistor are suppressed, thereby improving reliability.

[0356] By increasing the proportion of element M atoms in a metal oxide relative to the sum of the atomic numbers of all metal elements, the formation of oxygen vacancies in the metal oxide can be suppressed. Therefore, carrier generation caused by oxygen vacancies is suppressed, allowing for the formation of transistors with low off-state currents. Furthermore, variations in the transistor's electrical characteristics are suppressed, thus improving reliability.

[0357] The electrical characteristics and reliability of transistors vary depending on the composition of the metal oxides used in semiconductor layers 308 and 208. Therefore, by varying the composition of the metal oxides according to the required electrical characteristics and reliability of the transistors, semiconductor devices that possess both excellent electrical characteristics and high reliability can be realized.

[0358] When the metal oxide is an In-M-Zn oxide, the atomic ratio of In in this In-M-Zn oxide is preferably greater than or equal to the atomic ratio of M. Examples of such atomic ratios of the metal elements in this In-M-Zn oxide include In:M:Zn = 1:1:1, In:M:Zn = 1:1:1.2, In:M:Zn = 2:1:3, In:M:Zn = 3:1:2, In:M:Zn = 4:2:3, In:M:Zn = 4:2:4.1, In:M:Zn = 5:1:3, In:M:Zn = 5:1:6, In:M:Zn = 5:1:7, and In:M:Zn = 5:1:8. Compositions with indium (In:M:Zn) ratios of 6:1:6, 10:1:1, 10:1:3, 10:1:4, 10:1:6, 10:1:7, 10:1:8, 5:2:5, 10:1:10, 20:1:10, and 40:1:10, as well as their vicinity, are considered. Furthermore, vicinity composition includes a range of ±30% of the desired atomic ratio. Increasing the atomic ratio of indium in metal oxides can increase the on-state current of transistors or improve field-effect mobility.

[0359] In In-M-Zn oxides, the atomic ratio of In can also be less than that of M. Examples of such metallic atomic ratios in In-M-Zn oxides include In:M:Zn = 1:3:2, In:M:Zn = 1:3:3, In:M:Zn = 1:3:4, and compositions close to these ratios. By increasing the proportion of M atoms in the metal oxide, the formation of oxygen vacancies can be suppressed.

[0360] Note that when element M contains multiple metallic elements, the total proportion of the number of atoms of each metallic element can be considered as the proportion of the number of atoms of element M.

[0361] In this specification and other materials, the proportion of indium atoms relative to the sum of the atomic numbers of all the metallic elements contained herein is sometimes stated as the indium content. The same applies to other metallic elements.

[0362] By using materials with a high indium content in semiconductor layers 308 and 208, the on-state current of the transistor can be increased or the field-effect mobility can be improved. Furthermore, by including element M, the generation of oxygen vacancies can be suppressed. The content of element M (the ratio of the number of atoms of element M relative to the sum of the number of atoms of all metal-containing elements) is preferably 0.1% or more and 3% or less, more preferably 0.1% or more and 2% or less. This allows for the realization of transistors with excellent electrical characteristics. For example, metal oxides with an in:M:Zn ratio of 40:1:10 or similar are preferred. Element M is preferably one or more of the above elements, more preferably one or more selected from aluminum, gallium, tin, and yttrium. Specifically, metal oxides with an in:Sn:Zn ratio of 40:1:10 or similar can be used. Alternatively, metal oxides with an in:Al:Zn ratio of 40:1:10 or similar can be used.

[0363] Here, by using polycrystalline metal oxides for semiconductor layers 308 and 208, grain boundaries become recombination centers, trapping charge carriers, thus sometimes reducing the on-state current of the transistor. When using metal oxides with compositions that readily form polycrystalline structures, it is preferable to include elements that hinder crystallization. For example, compared to indium tin oxide (ITO), silicon-containing indium tin oxide (ITSO) is less likely to form polycrystalline structures, so it can be used for semiconductor layers 308 and 208. When using ITSO, the silicon content (the ratio of the number of silicon atoms relative to the sum of the number of atoms of all metal-containing elements) is preferably 1% or more and 20% or less, more preferably 3% or more and 20% or less, more preferably 3% or more and 15% or less, and more preferably 5% or more and 15% or less. Specifically, metal oxides with In:Sn:Si = 45:5:4, In:Sn:Si = 95:5:8, and similar metal oxides can be used.

[0364] In the compositional analysis of semiconductor layers 308 and 208, methods such as energy-dispersive X-ray spectrometry (EDX), X-ray photoelectron spectrometry (XPS), inductively coupled plasma mass spectrometry (ICP-MS), or inductively coupled plasma atomic emission spectrometry (ICP-AES) can be used. Alternatively, multiple methods can be combined. Note that the actual content of elements with low concentrations may differ from the analytically obtained content due to the influence of analytical precision. For example, when the content of element M is low, the analytically obtained content of element M may sometimes be lower than the actual content.

[0365] Metal oxides can be formed using sputtering or atomic layer deposition (ALD). Note that when metal oxides are formed using sputtering, the composition of the resulting metal oxide sometimes differs from that of the sputtering target. In particular, the zinc content in the resulting metal oxide can sometimes be reduced to about 50% of that in the sputtering target.

[0366] Semiconductor layer 308 and semiconductor layer 208 may also have a stacked structure comprising two or more metal oxide layers. The compositions of the two or more metal oxide layers comprising semiconductor layer 308 and semiconductor layer 208 may also be identical. By employing a stacked structure of metal oxide layers with the same composition, for example, the same sputtering target can be used for formation, thereby reducing manufacturing costs.

[0367] The compositions of the two or more metal oxide layers included in semiconductor layer 308 and semiconductor layer 208 can also be different from each other. For example, a stacked structure can be used, consisting of a first metal oxide layer with an In:M:Zn ratio of 1:3:4 or similar, and a second metal oxide layer disposed on the first metal oxide layer with an In:M:Zn ratio of 1:1:1 or similar. Furthermore, gallium, aluminum, or tin is particularly preferred as element M. The element M in the first metal oxide layer and the second metal oxide layer can be the same or different from each other. For example, the first metal oxide layer and the second metal oxide layer can also be composed of different IGZO layers.

[0368] For example, a stacked structure can be used, consisting of a first metal oxide layer with an In:Zn ratio of 4:1 or similar [atomic ratio] and a second metal oxide layer with an In:M:Zn ratio of 1:1:1 or similar [atomic ratio] disposed on the first metal oxide layer.

[0369] For example, a stacked structure selected from any one of indium oxide, indium gallium oxide and IGZO and any one of IAZO, IAGZO and ITZO (registered trademarks) can be used.

[0370] Note that when there is a stacked structure having a first metal oxide layer containing a first metal oxide and a second metal oxide layer containing a second metal oxide, and the composition of the first metal oxide is the same as that of the second metal oxide, it is sometimes difficult to clearly identify the boundary (interface) between the first metal oxide layer and the second metal oxide layer.

[0371] Semiconductor layers 308 and 208 preferably comprise crystalline metal oxides. Examples of crystalline metal oxide structures include CAAC (c-axis aligned crystal) structures, polycrystalline structures, and nano-crystal (nc) structures. By using crystalline metal oxides, the defect state density in semiconductor layers 308 and 208 can be reduced, thereby enabling highly reliable semiconductor devices.

[0372] Using highly crystalline metal oxides in the channel formation region can reduce the defect state density in that region. Conversely, using less crystalline metal oxides can enable transistors capable of carrying large currents.

[0373] When forming metal oxides using sputtering, the higher the substrate temperature during formation, the more crystalline the metal oxide can be formed. The substrate temperature during formation can be adjusted, for example, according to the temperature of the stage on which the substrate is placed during formation. Furthermore, the higher the oxygen flow rate ratio relative to the overall deposition gas used during formation (hereinafter also referred to as the oxygen flow ratio) or the oxygen partial pressure in the processing chamber, the more crystalline the metal oxide can be formed.

[0374] The crystallinity of semiconductor layers 308 and 208 can be analyzed, for example, by X-ray diffraction (XRD) patterns, transmission electron microscopy (TEM) images, or electron diffraction (ED) patterns. Alternatively, multiple of the above methods can be combined for analysis.

[0375] When metal oxides are used as semiconductor layers 308 and 208, it is preferable to minimize V in the channel formation region. O H is used to make it a high-purity intrinsic or substantially high-purity intrinsic. To obtain this V... O For metal oxides where H is sufficiently reduced, it is important to: remove impurities such as water and hydrogen from the metal oxide (sometimes described as dehydration or dehydrogenation); and to repair oxygen vacancies by supplying oxygen to the metal oxide. This is achieved by... O Metal oxides with sufficiently reduced impurities such as hydrogen (H) used in the channel formation region of transistors can impart stable electrical characteristics. Note that the process of supplying oxygen to metal oxides to repair oxygen vacancies is sometimes referred to as oxidation treatment.

[0376] When metal oxides are used as semiconductor layers 308 and 208, the carrier concentration in the channel formation region is preferably 1×10⁻⁶. 18 cm -3 Below, less than 1×10 is preferred. 17 cm -3 Further optimization of less than 1×10 16 cm -3 More preferably, less than 1×10 13 cm -3 Further optimization of less than 1×10 12 cm -3 Note that there is no lower limit to the carrier concentration in the channel formation region; for example, it can be 1 × 10⁻⁶. -9 cm -3 .

[0377] OS transistors exhibit minimal changes in electrical characteristics due to radiation exposure, meaning they possess high radiation tolerance and can be used in environments where radiation is likely to occur. OS transistors can also be described as having high reliability against radiation. For example, OS transistors can be used in the pixel circuitry of X-ray flat panel detectors. Furthermore, OS transistors can be used in semiconductor devices used in outer space. Examples of radiation include electromagnetic radiation (e.g., X-rays and gamma rays) and particle radiation (e.g., alpha rays, beta rays, proton radiation, and neutron radiation).

[0378] Semiconductor layers 308 and 208 may also contain layered materials used as semiconductors. Layered materials are a general term for materials with a layered crystalline structure. A layered crystalline structure is a structure formed by layers of covalent or ionic bonds stacked together through bonds weaker than covalent or ionic bonds, such as van der Waals bonds. Layered materials exhibit high conductivity per unit layer, i.e., high two-dimensional conductivity. By using a material with high two-dimensional conductivity as a semiconductor in the channel formation region, transistors with large on-state currents can be provided.

[0379] Examples of the aforementioned layered materials include graphene, silicene, and chalcogenides. Chalcogenides are compounds containing chalcogen elements (belonging to Group 16 elements). Furthermore, examples of chalcogenides include transition metal chalcogenides and Group 13 chalcogenides. Specific examples of transition metal chalcogenides suitable for use in the channel formation region of transistors include molybdenum sulfide (typically MoS2), molybdenum selenide (typically MoSe2), molybdenum telluride (typically MoTe2), tungsten sulfide (typically WS2), tungsten selenide (typically WSe2), tungsten telluride (typically WTe2), hafnium sulfide (typically HfS2), hafnium selenide (typically HfSe2), zirconium sulfide (typically ZrS2), and zirconium selenide (typically ZrSe2).

[0380] [Conductive layer 312a, conductive layer 312b, conductive layer 304, conductive layer 204, conductive layer 212a, conductive layer 212b, conductive layer 202]

[0381] Conductive layers 312a, 312b, 304, 204, 212a, 212b, and 202 can have either a single-layer structure or a stacked structure of two or more layers. Examples of materials that can be used for conductive layers 312a, 312b, 304, 204, 212a, 212b, and 202 include one or more of chromium, copper, aluminum, gold, silver, zinc, tantalum, titanium, tungsten, manganese, nickel, iron, cobalt, molybdenum, and niobium, as well as alloys containing one or more of these metals. Low-resistance conductive materials containing one or more of copper, silver, gold, and aluminum can be used for conductive layers 312a, 312b, 304, 204, 212a, 212b, and 202. Copper or aluminum are particularly advantageous in terms of mass production and are therefore preferred.

[0382] Conductive layers 312a, 312b, 304, 204, 212a, 212b, and 202 can be made of conductive metal oxides (oxide conductors). Examples of oxide conductors (OC) include indium oxide, zinc oxide, In-Sn oxide (ITO), In-Zn oxide, In-W oxide, In-W-Zn oxide, In-Ti oxide, In-Ti-Sn oxide, In-Sn-Si oxide (also known as silicon-containing ITO or ITSO), gallium-added zinc oxide, and In-Ga-Zn oxide. In particular, conductive oxides containing indium are preferred because of their high conductivity.

[0383] For example, oxygen vacancies are formed in metal oxides with semiconductor properties, and hydrogen is added to these vacancies to create donor levels near the conduction band. As a result, the conductivity of the metal oxide increases, making it a conductor. Metal oxides that can become conductors are called oxide conductors.

[0384] As conductive layers 312a, 312b, 304, 204, 212a, 212b, and 202, a stacked structure of conductive films containing the aforementioned oxide conductors (metal oxides) and conductive films containing metals or alloys can also be used. By using conductive films containing metals or alloys, wiring resistance can be reduced.

[0385] As conductive layers 312a, 312b, 304, 204, 212a, 212b, and 202, Cu-X alloy films (where X is Mn, Ni, Cr, Fe, Co, Mo, Ta, or Ti) can also be used. By using Cu-X alloy films, processing can be performed using wet etching, thereby reducing manufacturing costs.

[0386] Note that the materials used for conductive layers 312a, 312b, 304, 204, 212a, 212b and 202 may be the same or different.

[0387] Conductive layers 312a and 312b have regions that contact the semiconductor layer 308. When a metal oxide is used as the semiconductor layer 308, there is a concern that if an easily oxidizable metal (e.g., aluminum) is used as the conductive layers 312a and 312b, insulating oxides (e.g., aluminum oxide) will form between the conductive layers 312a and 308, and between the conductive layers 312b and 308, hindering their conductivity. Therefore, conductive layers 312a and 312b are preferably made of conductive materials that are not easily oxidized, conductive materials that maintain low resistance even when oxidized, or oxide conductive materials.

[0388] For conductive layers 312a and 312b, materials such as titanium, tantalum nitride, titanium nitride, nitrides containing titanium and aluminum, nitrides containing tantalum and aluminum, ruthenium, ruthenium oxide, ruthenium nitride, oxides containing strontium and ruthenium, and oxides containing lanthanum and nickel are preferably used. These materials are preferred because they are conductive materials that are not easily oxidized or maintain low resistance even if oxidized. Note that when conductive layer 312a has a stacked structure, at least the layer in contact with semiconductor layer 308 preferably uses a conductive material that is not easily oxidized.

[0389] The conductive layers 312a and 312b can use the aforementioned oxide conductors. Specifically, conductive oxides such as indium oxide, zinc oxide, ITO, In-Zn oxide, In-W oxide, In-W-Zn oxide, In-Ti oxide, In-Ti-Sn oxide, In-Sn oxide containing silicon, or zinc oxide with gallium added can be used.

[0390] The conductive layers 312a and 312b may also be made of nitride conductors. Examples of nitride conductors include tantalum nitride and titanium nitride.

[0391] Here, in capacitor 350, a conductive layer 312b is provided on the insulating layer 320b. As described above, the conductive layer 312b is preferably made of a conductive material that is not easily oxidized, a conductive material that maintains low resistance even if oxidized, or an oxide conductive material. Furthermore, the amount of oxygen released from the insulating layer 320b is less than the amount of oxygen released from the insulating layer 310b. Therefore, the possibility of the conductive layer 312b having a region in contact with the insulating layer 320b being oxidized and its resistance becoming high is very low.

[0392] Conductive layers 312a, 312b, and 304 can also have a stacked structure. For example, conductive layer 312a can also have a two-layer structure. That is, conductive layer 312a can, for example, have a stacked structure of conductive layer 312a_1 (not shown) and conductive layer 312a_2 (not shown) on conductive layer 312a_1.

[0393] The conductive layer 312a_2, which has a region in contact with the semiconductor layer 308, is preferably made of a conductive material that is not easily oxidized, a conductive material that maintains low resistance even if oxidized, or an oxide conductive material. Materials that can be used for the conductive layer 312a_2 can be found in the description of the conductive layer 312a.

[0394] The conductive layer 312a_1 does not have a region in contact with the semiconductor layer 308, therefore there are no particular limitations on the materials used. For example, the conductive layer 312a_1 is preferably made of a material with a lower resistivity than the conductive layer 312a_2. This reduces the resistance of the conductive layer 312a. For example, the conductive layer 312a_2 can be made of In-Sn-Si oxide (ITSO), and the conductive layer 312a_1 can be made of copper or tungsten.

[0395] Furthermore, the thickness of conductive layer 312a_1 can be the same as or different from the thickness of conductive layer 312a_2. For example, a material with a lower resistivity than conductive layer 312a_2 can be used for conductive layer 312a_1, and the thickness of conductive layer 312a_1 can be greater than the thickness of conductive layer 312a_2. This can reduce the resistance of conductive layer 312a.

[0396] Furthermore, the end of conductive layer 312a_2 may or may not be the same as the end of conductive layer 312a_1. For example, conductive layer 312a_2 may be provided in a manner that covers conductive layer 312a_1. That is, conductive layer 312a_2 is in contact with the top and side surfaces of conductive layer 312a_1. Conductive layer 312a_2 may also be described as having a portion that protrudes beyond the end of conductive layer 312a_1.

[0397] In addition, the structure of the conductive layer 312a described above can also be used in other structural examples.

[0398] [Insulation layer 306]

[0399] The insulating layer 306 may have a single-layer structure or a stacked structure of two or more layers. The insulating layer 306 preferably comprises one or more inorganic insulating films. Examples of materials that can be used for inorganic insulating films include oxides, nitrides, oxynitrides, and oxynitrides. The insulating layer 306 may use materials that are also suitable for the insulating layer 310.

[0400] The insulating layer 306 has a region in contact with the semiconductor layer 308 and the semiconductor layer 208. When the semiconductor layer 308 and the semiconductor layer 208 are metal oxides, the film constituting the insulating layer 306 that is in contact with the semiconductor layer 308 and the semiconductor layer 208 preferably uses any one of the aforementioned oxides and oxynitrides. Furthermore, the insulating layer 306 preferably uses a film that releases oxygen upon heating.

[0401] Specifically, when the insulating layer 306 has a single-layer structure, the insulating layer 306 preferably uses an oxide or an oxynitride. Specifically, the insulating layer 306 can use silicon oxide or silicon oxynitride.

[0402] When the insulating layer 306 has a stacked structure, it is preferable that the insulating film on the side in contact with the semiconductor layer 308 and the semiconductor layer 208 comprises an oxide or an oxynitride, and the insulating film on the side in contact with the conductive layer 304 and the conductive layer 204 comprises a nitride or an oxynitride. For example, silicon oxide or silicon oxynitride can be used as the oxide or oxynitride. For example, silicon nitride or silicon oxynitride can be used as the nitride or oxynitride.

[0403] Silicon nitride and silicon oxynitride are characterized by the low amount of impurities (e.g., water and hydrogen) they release and the low permeability of oxygen and hydrogen, and therefore can be used as insulating layer 306. Since impurity diffusion from insulating layer 306 to semiconductor layer 308 and semiconductor layer 208 is suppressed, good electrical characteristics of transistors can be achieved and reliability can be improved.

[0404] Note that in microtransistors, the gate leakage current sometimes increases when the thickness of the gate insulating layer is small. By using a material with a relatively high permittivity (also known as a high-k material) in the gate insulating layer, it is possible to achieve low voltage operation of the transistor while maintaining the physical thickness. Examples of high-k materials that can be used for the insulating layer 306 include gallium oxide, hafnium oxide, zirconium oxide, oxides containing aluminum and hafnium, oxynitrides containing aluminum and hafnium, oxides containing silicon and hafnium, oxynitrides containing silicon and hafnium, and nitrides containing silicon and hafnium.

[0405] [Insulation layer 395]

[0406] The insulating layer 395, which serves as a protective layer for transistors 300, 200, and capacitor 350, is preferably made of a material from which impurities do not easily diffuse. By providing the insulating layer 395, the diffusion of impurities from the outside into the transistor can be effectively suppressed, thereby improving the reliability of the semiconductor device. Examples of impurities include water and hydrogen.

[0407] The insulating layer 395 can be an insulating layer containing inorganic materials or an insulating layer containing organic materials. For example, the insulating layer 395 can use inorganic materials such as oxides, oxynitrides, oxynitrides, or nitrides. More specifically, one or more of silicon nitride, silicon oxynitride, silicon oxynitride, aluminum oxide, aluminum oxynitride, aluminum nitride, hafnium oxide, and hafnium aluminate can be used. For example, one or more of acrylic resin and polyimide resin can be used as organic materials. Photosensitive materials can also be used as organic materials. Furthermore, two or more of the above-described insulating films can be laminated. The insulating layer 395 can also have a laminated structure containing both inorganic and organic insulating layers.

[0408] [Substrate 302]

[0409] While there are no particular restrictions on the material of substrate 302, it must at least possess heat resistance capable of withstanding subsequent heat treatments. For example, single-crystal or polycrystalline semiconductor substrates made of silicon or silicon carbide, compound semiconductor substrates made of silicon-germanium, SOI substrates, glass substrates, quartz substrates, sapphire substrates, ceramic substrates, or organic resin substrates can be used as substrate 302. Furthermore, semiconductor elements can also be disposed on substrate 302. Note that the shapes of the semiconductor substrate and the insulating substrate can be circular or angular.

[0410] A flexible substrate can also be used as substrate 302, and transistors such as 300 can be formed directly on the flexible substrate. Alternatively, a release layer can be provided between substrate 302 and transistors such as 300. By providing a release layer, a portion or all of a semiconductor device can be fabricated on the release layer and then separated from substrate 302 and transferred to another substrate. In this case, transistors such as 300 can also be transferred to a substrate with low heat resistance or a flexible substrate.

[0411] [Example of variation]

[0412] Figure 15 A cross-sectional view of a transistor 300A, which can be used in one aspect of the present invention, is shown. The main difference between transistor 300A and transistor 300 shown in FIG. 12 is the inclusion of a back gate. Note that reference can be made to the description of transistor 300 described above, therefore a detailed description is omitted.

[0413] Transistor 300A includes conductive layer 312a, conductive layer 303, insulating layer 307, insulating layer 310, semiconductor layer 308, conductive layer 312b, insulating layer 306, and conductive layer 304. The layers constituting transistor 300A can have either a single-layer structure or a stacked structure.

[0414] A conductive layer 312a is disposed on the substrate 302. The conductive layer 312a is used as one of the source electrode and drain electrode of the transistor 300A.

[0415] The insulating layer 307 is located on the conductive layer 312a. The insulating layer 307 is provided in such a way that it covers the top surface and the side surface of the conductive layer 312a.

[0416] The conductive layer 303 is located on the insulating layer 307. The conductive layer 312a and the conductive layer 303 are electrically insulated from each other by the insulating layer 307. An opening 348 is provided in the region of the conductive layer 303 that overlaps with the conductive layer 312a, leading to the insulating layer 307.

[0417] An insulating layer 310 is disposed on the insulating layer 307 and the conductive layer 303. The insulating layer 310 is disposed such that it covers the top and side surfaces of the conductive layer 303 and the top surface of the insulating layer 307.

[0418] The insulating layer 310 preferably has a laminated structure. Figure 15 An example is shown of an insulating layer 310 having an insulating layer 310a, an insulating layer 310b on the insulating layer 310a, and an insulating layer 310c on the insulating layer 310b.

[0419] An insulating layer 310a is located on the insulating layer 307 and the conductive layer 303. The insulating layer 310a is disposed such that it covers the top and side surfaces of the conductive layer 303. The insulating layer 310a is disposed such that it covers a portion of the opening 348. The insulating layer 310a contacts the insulating layer 307 through the opening 348.

[0420] An insulating layer 310b is provided on the insulating layer 310a, and an insulating layer 310c is provided on the insulating layer 310b. An opening 341 is provided in the insulating layer 307 and the insulating layer 310 to reach the conductive layer 312a.

[0421] Conductive layer 312b is located on insulating layer 310c. An opening 343 overlapping with opening 341 is provided in conductive layer 312b. Conductive layer 312b is used as another of the source and drain electrodes of transistor 300A. Conductive layer 312b has a region overlapping conductive layer 312a, separated by insulating layer 307 and insulating layer 310.

[0422] In this specification, the top surface shape of opening 348 refers to the shape of the top or bottom end of the conductive layer 303 on the side of opening 348. Note that, similar to openings 341 and 343, there is no limitation on the top surface shape of opening 348.

[0423] When the top surfaces of openings 341 and 348 are circular, they are preferably concentric. This ensures that, in cross-sectional view, the shortest distance between the semiconductor layer 308 and the conductive layer 303 on both sides of opening 341 is equal. However, openings 341 and 348 are sometimes not concentric.

[0424] Semiconductor layer 308 contacts the top surface of conductive layer 312a, the side surface of insulating layer 307, the side surface of insulating layer 310, and the top surface and side surface of conductive layer 312b. Semiconductor layer 308 is disposed in a manner that covers openings 341 and 343. Semiconductor layer 308 is disposed in a manner that contacts the side surface of insulating layer 307 and insulating layer 310 on the side of opening 341 and the side surface of conductive layer 312b on the side of opening 343 (or, in other words, a portion of the top surface and the side surface on the side of opening 343). Semiconductor layer 308 contacts conductive layer 312a through openings 341 and 343.

[0425] Figure 15 An example is shown in which the end of the semiconductor layer 308 contacts the top surface of the conductive layer 312b, but the invention is not limited to this. The semiconductor layer 308 may also cover the end of the conductive layer 312b, and the end of the semiconductor layer 308 may also contact the top surface of the insulating layer 310c.

[0426] An insulating layer 306 is located on an insulating layer 310c, a semiconductor layer 308, and a conductive layer 312b. The insulating layer 306 is disposed such that it covers openings 341 and 343 through the semiconductor layer 308. A portion of the insulating layer 306 is used as the gate insulating layer of the transistor 300A.

[0427] The conductive layer 304 is located on the insulating layer 306. The conductive layer 304 overlaps with the semiconductor layer 308 through the insulating layer 306. The conductive layer 304 is used as the gate electrode of the transistor.

[0428] In transistor 300A, semiconductor layer 308 has a region that overlaps with conductive layer 304 across insulating layer 306 and with conductive layer 303 across a portion of insulating layer 310 (especially insulating layers 310a and 310b). In other words, there is a region in semiconductor layer 308 sandwiched between conductive layer 304 and conductive layer 303, wherein insulating layer 306 is sandwiched between semiconductor layer 308 and conductive layer 304 and a portion of insulating layer 310 (especially insulating layers 310a and 310b) is sandwiched between semiconductor layer 308 and conductive layer 303.

[0429] The conductive layer 303 is used as the back gate electrode of the transistor 300A. In addition, a portion of the insulating layer 310 is used as the back gate insulating layer of the transistor 300A.

[0430] By providing a back gate electrode in transistor 300A, the potential on the back channel side of semiconductor layer 308 can be fixed, and the saturation of transistor 300A can be improved.

[0431] Because transistor 300A includes a back gate electrode, the potential on the back channel side of semiconductor layer 308 can be fixed, thus suppressing threshold voltage drift. Here, when the threshold voltage of the transistor drifts, the drain current (hereinafter referred to as the cutoff current) flowing when the gate voltage is 0V sometimes increases. By suppressing the threshold voltage drift of transistor 300A, a transistor with a small cutoff current can be achieved. Note that the state with a small cutoff current is sometimes referred to as normally off.

[0432] Notice, Figure 15 An example is shown where the semiconductor layer 308, insulating layer 306, and conductive layer 304 cover openings 341 and 343, but one aspect of the invention is not limited thereto. Alternatively, the insulating layer 307, insulating layer 310, and conductive layer 312b and conductive layer 312a may form a step, and the semiconductor layer 308, insulating layer 306, and conductive layer 304 may be disposed along the step.

[0433] <Application examples for switch sections>

[0434] In one embodiment of the present invention, for example, transistors 200, 200A, 300, and 300A, etc., included in semiconductor devices 100A and 100B as shown in Embodiment 1 above, may be used. In particular, transistors 200 and 300A, etc., including a back gate electrode, may be used as transistor M11 included in the switching section 101A of semiconductor device 100A, and the back gate electrode may be electrically connected to the drain electrode. Similarly, transistors 200 and 300A, etc., including a back gate electrode, may be used as transistor M21 included in the switching section 101B of semiconductor device 100B, and the back gate electrode may be electrically connected to the drain electrode.

[0435] Figure 16A This is a top view showing a structural example of a switching section 101A in which transistors 200 and 200A are used in a semiconductor device 100A. Figure 16B It is along Figure 16A The cross-sectional view of the section along the dotted line C1-C2 is shown. Note that the descriptions of transistors 200 and 200A above can be referred to as appropriate, so detailed descriptions are sometimes omitted here.

[0436] Figure 16A and Figure 16B The semiconductor device 20A, which corresponds to the switch section 101A, is shown. That is, the semiconductor device 20A includes a transistor 200, which corresponds to transistor M11, and a transistor 200A, which corresponds to transistor M12.

[0437] One of the source and drain of transistor 200 is electrically connected to conductive layer 212_2. The other of the source and drain of transistor 200 is electrically connected to conductive layer 212_1. One of the source and drain of transistor 200A is electrically connected to conductive layer 212_2. The other of the source and drain of transistor 200A is electrically connected to conductive layer 212_3. The gate of transistor 200 and the gate of transistor 200A are electrically connected to conductive layer 204. The back gate of transistor 200 is electrically connected to conductive layer 202_1. Conductive layer 202_1 is electrically connected to conductive layer 212_1 through opening 349_1 provided in insulating layer 306 and insulating layer 320.

[0438] Here, semiconductor layer 208_1 included in transistor 200 and semiconductor layer 208_2 included in transistor 200A are both equivalent to semiconductor layer 208. Conductive layer 202_1 is equivalent to conductive layer 202. Conductive layers 212_1, 212_1 and 212_2 are all equivalent to conductive layer 212.

[0439] Note that conductive layer 204 corresponds to wiring IN11 in semiconductor device 100A. Conductive layers 212_1 and 202_1 correspond to wiring OUT11. Conductive layer 212_2 corresponds to wiring NL11. Conductive layer 212_3 corresponds to wiring VLS.

[0440] like Figure 16A As shown, transistor 200A, transistor 200, and opening 349_1 are located along the channel length direction of transistor 200 and transistor 200A. Figure 16A Arranged in a left-right direction (in the middle).

[0441] Additionally, the conductive layer 202_1 is oriented towards the channel width direction of the transistor 200 ( Figure 16A One side of the vertical direction (in the middle) Figure 16A The conductive layer 204 is arranged in a circuitous manner (on the upper side of the middle). Additionally, the conductive layer 204 is positioned on the opposite side (in the channel width direction of transistors 200 and 200A) Figure 16A The semiconductor device 20A is configured in a roundabout manner (located on the lower side of the transistor). This configuration reduces the area of ​​overlap between conductive layer 202_1 and conductive layer 204. Therefore, the parasitic capacitance between the gate and back gate of transistor 200 and transistor 200A can be reduced. Thus, for example, when semiconductor device 20A is used in a drive circuit, the operating speed of the drive circuit can be increased.

[0442] Furthermore, in the conductive layer 202_1, the width of the region of the bypass transistor 200 can be made smaller than the width of the region serving as the back gate of the transistor 200. This reduces the area occupied by the semiconductor device 20A. Therefore, miniaturization of the driving circuit using the semiconductor device 20A and the display device using the driving circuit can be achieved.

[0443] Furthermore, in the conductive layer 204, the width of the regions serving as the gate of transistor 200 and transistor 200A can be made smaller than the width of each of the regions serving as the gate of transistor 200 and transistor 200A. This reduces the area occupied by the semiconductor device 20A. Therefore, miniaturization of the driving circuit using the semiconductor device 20A and the display device using the driving circuit can be achieved.

[0444] Figure 17A This is a top view showing a modified example of the semiconductor device 20A. Figure 17A The semiconductor device 20A1 shown differs from the semiconductor device 20A in the configuration of the conductive layer 204.

[0445] like Figure 17A As shown, the conductive layer 204 is positioned on one side of the channel width direction of transistors 200 and 200A. Figure 17AThe transistor 20A1 is configured in a roundabout manner (on the upper side). In other words, on the outside of the transistor 200, a portion of the conductive layer 204 overlaps with a portion of the conductive layer 202_1. This configuration reduces the area occupied by the semiconductor device 20A1. Therefore, miniaturization of the driving circuit using the semiconductor device 20A1 and the display device using the driving circuit can be achieved.

[0446] Figure 17B This is a top view showing a modified example of the semiconductor device 20A. Figure 17B The semiconductor device 20A2 shown differs from the semiconductor device 20A in the configuration of transistors 200 and 200A.

[0447] like Figure 17B As shown, transistor 200A, transistor 200, and opening 349_1 are located in the channel width direction of transistor 200 and transistor 200A. Figure 17B The conductive layer 202_1 is arranged vertically (in the vertical direction). Therefore, the conductive layer 202_1 can be arranged without detours around the transistors 200. Furthermore, the conductive layer 204 can be arranged without detours around the transistors 200 and 200A. This arrangement reduces the area occupied by the semiconductor device 20A2. Therefore, miniaturization of the driving circuit using the semiconductor device 20A2 and the display device using the driving circuit can be achieved.

[0448] Note that in Figure 16A In the semiconductor device 20A shown, the length of the conductive layer 212_2 can be less than Figure 17B The length of the conductive layer 212_2 of the semiconductor device 20A2 shown is illustrated. This reduces the parasitic resistance of the wiring NL11. Therefore, especially when the drain current of transistors 200 and 200A is large, the impact of the parasitic resistance of the wiring NL11 can be reduced.

[0449] Figure 18A and Figure 18B These are a top view and a cross-sectional view showing a modified example of the semiconductor device 20A. Figure 18A and Figure 18B The semiconductor device 20B shown differs from semiconductor device 20A in that semiconductor device 20B does not include conductive layer 212_2, and transistors 200 and 200A share a continuously disposed semiconductor layer 208_1. In semiconductor layer 208_1 of semiconductor device 20B, the area between the channel formation region of transistor 200 and the channel formation region of transistor 200A corresponds to wiring NL11.

[0450] Because semiconductor device 20B does not include conductive layer 212_2, the distance between transistor 200 and transistor 200A can be smaller than that between semiconductor device 20A. This reduces the area occupied by semiconductor device 20B. Therefore, miniaturization of the driving circuit using semiconductor device 20B and the display device using the driving circuit can be achieved.

[0451] Figure 19A and Figure 19B These are a top view and a cross-sectional view showing a modified example of the semiconductor device 20A. Figure 19A and Figure 19B The semiconductor device 20C shown differs from the semiconductor device 20A in that: in the semiconductor device 20C, a transistor 200 including a back gate is used as a transistor equivalent to transistor M12, and a conductive layer 202_2 having a region serving as the back gate is provided.

[0452] A conductive layer 202_2 having a region serving as the back gate of transistor 200, equivalent to transistor M12, in the channel width direction of the transistor ( Figure 19A It is configured to extend in the vertical direction and is electrically connected to the conductive layer 204, which corresponds to wiring IN11, through openings 349_2 provided in insulating layers 306 and 320. In other words, the semiconductor device 20C is equivalent to... Figure 3A The semiconductor device 100A shown is shown.

[0453] Figure 20A and Figure 20B These are a top view and a cross-sectional view showing a modified example of the semiconductor device 20A. Figure 20A and Figure 20B The semiconductor device 20D shown differs from the semiconductor device 20A in that it uses a vertical transistor 300 as the transistor equivalent to transistor M12. Furthermore, the description of transistor 300 may be omitted here as appropriate with reference to the description of transistor 300 described above.

[0454] The conductive layer 204 in transistor 300, which corresponds to transistor M12, is equivalent to the conductive layer 304 of transistor 300. The conductive layer 312a corresponds to wiring VLS. The conductive layer 312b is electrically connected to the conductive layer 212_2, which corresponds to wiring NL11, through an opening 349_3 provided in the insulating layer 306.

[0455] In the semiconductor device 20D, by using transistor 300, the on-state current can be increased while the occupied area can be reduced. Therefore, it is possible to improve the operating speed and miniaturize the driving circuit using the semiconductor device 20D and the display device using the driving circuit.

[0456] Figure 21A and Figure 21B These are a top view and a cross-sectional view showing a modified example of the semiconductor device 20D. Figure 21A and Figure 21B In the semiconductor device 20E shown, conductive layers 212_2 and 312b are not included, and transistors 200 and 300 share a continuously disposed semiconductor layer 208_1, which differs from semiconductor device 20A. Here, semiconductor layer 208_1 in transistor 300, which corresponds to transistor M12, is equivalent to semiconductor layer 308 of transistor 300 as described above. In semiconductor layer 208_1 of semiconductor device 20E, the region between the channel formation region of transistor 200 and the channel formation region of transistor 300 corresponds to wiring NL11.

[0457] Because semiconductor device 20E does not include conductive layer 212_2, the distance between transistors 200 and 300 can be smaller than that between semiconductor device 20D. This reduces the area occupied by semiconductor device 20E. Therefore, miniaturization of the driving circuit using semiconductor device 20E and the display device using the driving circuit can be achieved.

[0458] In addition, since the conductive layer 312b is not included, the process cost can be reduced.

[0459] Note that in the above description, by replacing transistor M11 with transistor M21, transistor M12 with transistor M22, wiring IN11 with wiring IN22, wiring VLS with wiring OUT21, and wiring OUT11 with wiring VLD, semiconductor devices 20A to 20E can each be used in the switching section 101B.

[0460] In another aspect of the present invention, the semiconductor device that can be used in each of the switching section 101A and the switching section 101B is not limited to semiconductor devices 20A to 20E, and semiconductor devices with appropriate combinations of structures can also be used.

[0461] The structures shown in this embodiment can be appropriately combined with structures shown in other embodiments. Furthermore, in this specification, where multiple structural examples are shown in one embodiment, these examples can be appropriately combined and used.

[0462] (Implementation Method 3)

[0463] In this embodiment, a display device according to one aspect of the present invention is described.

[0464] In addition, at least a portion of the semiconductor device 100A and semiconductor device 100B shown in Embodiment 1 above can be used in a display device and a module including the display device according to one aspect of the present invention.

[0465] As a module that includes the display device, examples include modules in which the display device is equipped with connectors such as flexible printed circuit boards (FPC) or TCP (Tape Carrier Package), or modules in which integrated circuits (ICs) are mounted via COG (Chip On Glass) or COF (Chip On Film).

[0466] <Example of a display device structure>

[0467] Figure 22A This is a perspective view illustrating a structural example of a display device 400 according to one aspect of the present invention.

[0468] The display device 400 has a structure that bondes substrate 411 and substrate 451. Figure 22A In the image, substrate 411 is represented by a dashed line.

[0469] The display device 400 includes a display section 452, a circuit section 454a, a circuit section 454b, a connection section 457, and a wiring section 458. Figure 22A An example is shown where a display device 400 is equipped with IC456 and FPC459. Therefore, it is also possible to... Figure 22A The structure shown is called a display module, which includes a display device 400, an IC, and an FPC.

[0470] Circuit section 454a includes, for example, a scan line drive circuit (also known as a gate driver or scan driver). Furthermore, circuit section 454b includes, for example, a signal line drive circuit (also known as a source driver or data driver).

[0471] 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. The 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.

[0472] Figure 22A An example is shown where IC 456 is mounted on substrate 451 using a COG or COF method. IC 456 can be, for example, an IC that includes 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 do not necessarily need to have an IC mounted on them. Alternatively, the IC can also be mounted on an FPC using a COF method or the like.

[0473] Alternatively, IC456 and circuit section 454a, or both, can be used to construct a scan line driving circuit. In this case, IC456 is sometimes referred to as a gate driver IC. Alternatively, IC456 and circuit section 454b, or both, can be used to construct a signal line driving circuit. In this case, IC456 is sometimes referred to as a source driver IC.

[0474] Display unit 452 is an image display area in display device 400, including a plurality of pixels 455 arranged periodically. Figure 22A The image shown is a magnified view of pixel 455.

[0475] Figure 22A The pixel 455 shown includes pixel 453R, which emits red (R) light; pixel 453G, which emits green (G) light; and pixel 453B, which emits blue (B) light. Full-color display can be achieved by using pixels 453R, 453G, and 453B to form a single pixel 455. Pixels 453R, 453G, and 453B are all used as sub-pixels. Figure 22A The display device 400 shown illustrates an example where pixels 453R, 453B, and 453G, used as subpixels, are arranged in a stripe pattern. Note that the number of subpixels constituting a pixel 455 is not limited to three; it can be four or more. For example, it may include four subpixels that respectively emit R, G, B, and white (W) light. Alternatively, it may include four subpixels that respectively emit R, G, B, and yellow (Y) light.

[0476] Note that in this specification, etc., sometimes the component related to red light is marked with the identification symbol "R", the component related to green light is marked with the identification symbol "G", and the component related to blue light is marked with the identification symbol "B" to describe each component separately. Furthermore, sometimes these identification symbols are omitted to describe the common components. For example, when it is necessary to distinguish multiple pixels 453, they are sometimes shown as pixel 453R, pixel 453G, or pixel 453B. Additionally, when it is not necessary to distinguish between pixels 453R, pixel 453G, and pixel 453B, they are sometimes simply shown as pixel 453.

[0477] Pixels 453R, 453G, and 453B all include a display element and a circuit (pixel circuit) that controls the driving of the display element.

[0478] The connecting portion 457 is disposed on the outer side of the display portion 452. The connecting portion 457 may be disposed along one or more edges of the display portion 452. There may also be one or more connecting portions 457. Figure 22AAn example is shown where the connection portion 457 is arranged around the four sides of the display portion. In the connection portion 457, the common electrode of the display element is electrically connected to the wiring portion 458, and a potential can be supplied to the common electrode.

[0479] Here, for example, a semiconductor device according to one aspect of the present invention can be used in at least a portion of the display unit 452, circuit unit 454a, and circuit unit 454b included in the display device 400.

[0480] For example, by using at least a portion of the semiconductor devices 100A and 100B shown in Embodiment 1 above in one or both of the circuit sections 454a and 454b, the reliability of the display device can be improved. Furthermore, for example, by using a vertical transistor such as the transistor 300 shown in Embodiment 2 above, the area occupied by the driving circuit can be reduced, thereby enabling a display device with a narrow bezel.

[0481] Furthermore, for example, by using the vertical transistors of the transistor 300 shown in Embodiment 2 in the pixel circuit included in the display unit 452, the occupied area of ​​the pixel circuit can be reduced, thereby realizing a high-definition display device. 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.

[0482] The display device according to one aspect of the present invention can also have the function of a touch panel. For example, various detection elements (or sensor elements) capable of detecting the approach or contact of a detection object such as a finger can also be used in the display device.

[0483] Examples of sensor types include capacitive, resistive film, surface acoustic wave, infrared, optical, and pressure-sensitive types.

[0484] As electrostatic capacitive types, there are surface-type electrostatic capacitive types and projection-type electrostatic capacitive types. Furthermore, as projection-type electrostatic capacitive types, there are self-capacitance types and mutual-capacitance types. Mutual-capacitance types are preferred because they allow for simultaneous multi-point sensing.

[0485] Examples of touch panels include Out-Cell, On-Cell, and In-Cell types. Note that an In-Cell touch panel refers to a structure in which electrodes constituting the detection element are provided on one or both of the substrate supporting the display element (also called the display device) and the opposing substrate.

[0486] [Pixel arrangement]

[0487] Figures 22B to 22FThis is a top view illustrating the pixel arrangement. In one aspect of the display device of the present invention, there are no particular limitations on the pixel arrangement, and various arrangements can be used. For example, a stripe arrangement can be cited as a pixel arrangement (see [reference]). Figure 22B S-shaped stripe arrangement (refer to) Figure 22C Delta arrangement (refer to) Figure 22D ), zigzag arrangement (see reference) Figure 22E ) and Pentile arrangement (refer to Figure 22F Examples include mosaic patterns, diamond patterns, and Bayer patterns.

[0488] In addition, Figures 22B to 22F In this context, 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 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 within that sub-pixel. The top surface shape and size of each sub-pixel can be determined independently. Note that the configurations of pixels 453R, 453G, and 453B can be appropriately interchanged. Furthermore, the arrangement of the display elements and pixel circuits can be either the same or different.

[0489] Here, the Pentile arrangement is a special pixel arrangement that improves sharpness in a pseudo-method. Therefore, in a display device, for example, a stripe arrangement can be used. In one aspect of the present invention, by using vertical transistors, such as the transistor 300 shown in Embodiment 2 above, as part or all of the transistors constituting the pixel circuit, the area occupied by the pixel circuit can be reduced. Therefore, as a pixel arrangement, for example, a stripe arrangement can be used instead of a Pentile arrangement without reducing the sharpness of the display device.

[0490] [Display element]

[0491] Various components can be used as display elements, such as liquid crystal elements and light-emitting elements. In addition, MEMS (Micro Electro Mechanical Systems) elements using shutter-based or optical interference methods, or display elements employing microencapsulation, electrophoresis, electrowetting, or electronic powder fluid methods (registered trademark) can be used. Furthermore, QLEDs (Quantum-dot LEDs) utilizing light sources and color conversion technology based on quantum dot materials can also be used.

[0492] Examples of display devices using liquid crystal elements include transmissive liquid crystal displays, reflective liquid crystal displays, and transflective liquid crystal displays.

[0493] Examples of display device modes that can be used with liquid crystal elements include Vertical Alignment (VA) mode, FFS (Fringe Field Switching) mode, IPS (In-Plane-Switching) mode, TN (Twisted Nematic) mode, ASM (Axially Symmetric aligned Micro-cell) mode, OCB (Optically Compensated Birefringence) mode, FLC (Ferroelectric Liquid Crystal) mode, AFLC (Anti-Ferroelectric Liquid Crystal) mode, ECB (Electrically Controlled Birefringence) mode, and guest-host mode. Examples of VA modes include MVA (Multi-Domain Vertical Alignment) mode, PVA (Patterned Vertical Alignment) mode, and ASV (Advanced Super View) mode.

[0494] Examples of liquid crystal materials that can be used in liquid crystal elements include thermotropic liquid crystals, low-molecular-weight liquid crystals, high-molecular-weight liquid crystals, polymer-dispersed liquid crystals (PDLCs), polymer network liquid crystals (PNLCs), ferroelectric liquid crystals, and antiferroelectric liquid crystals. These liquid crystal materials exhibit cholesteric, smectic, cubic, chiral nematic, isotropic, or blue phases depending on the conditions. Furthermore, either positive or negative liquid crystals can be used as liquid crystal materials.

[0495] Examples of light-emitting elements include self-emissive light-emitting elements such as LEDs (Light Emitting Diodes), organic EL (ElectroLuminescence) elements (also known as OLEDs (Organic LEDs)), and semiconductor lasers. For example, Mini LEDs or Micro LEDs can be used as LEDs.

[0496] Light-emitting materials contained in light-emitting elements include, for example, substances that emit fluorescence (fluorescent materials), substances that emit phosphorescence (phosphorescent materials), substances that exhibit thermally activated delayed fluorescence (thermally activated delayed fluorescence (TADF) materials), and inorganic compounds (quantum dot materials, etc.).

[0497] The light-emitting element can emit colors such as infrared, red, green, blue, cyan, magenta, yellow, or white. Furthermore, when the light-emitting element has a microcavity structure, the color purity can be further improved.

[0498] In a light-emitting element, one of the two electrodes is used as the anode (also called the anode electrode) and the other electrode is used as the cathode (also called the cathode electrode).

[0499] In this embodiment, the example of using a light-emitting element as a display element will be described. In particular, the example of using an organic EL element as a light-emitting element will be described. Therefore, one aspect of the present invention is a display device using an organic EL element.

[0500] One embodiment of the display device of the present invention can be any of the following structures: a top emission type that emits light in the direction opposite to that of the substrate on which the light-emitting element is formed, a bottom emission type that emits light in the direction of the substrate on which the light-emitting element is formed, and a dual emission type that emits light in both directions.

[0501] Furthermore, for example, by using a vertical transistor such as the transistor 300 shown in Embodiment 2 above, the occupied area of ​​the pixel circuit can be reduced, thereby increasing the aperture ratio of the pixels in the bottom-emitting display device. For example, a display device with an aperture ratio of 50% or more, 55% or more, or 60% or more can be realized.

[0502] Note that in this specification, aperture ratio refers to the proportion of the area from which light is emitted relative to the pixel area.

[0503] <Example of circuit structure for a display device>

[0504] Figures 23A to 23E This is a block diagram illustrating an example of the circuit structure of a display device according to one aspect of the present invention.

[0505] like Figure 23A As shown, the display device 460 includes a display unit 462, a first driving circuit unit 463, and a second driving circuit unit 464. The display unit 462 includes, for example, a plurality of pixels 461 arranged in a matrix of m rows and n columns (where m and n are both integers of 2 or more).

[0506] Note that when at least a portion of the display device 460 is used in the aforementioned display device 400, pixel 461 corresponds to pixel 453, display unit 462 corresponds to display unit 452, first driving circuit unit 463 corresponds to circuit unit 454a, and second driving circuit unit 464 corresponds to circuit unit 454b. Note that sometimes both the first driving circuit unit 463 and the second driving circuit unit 464 include at least a portion of IC 456.

[0507] exist Figure 23A In the diagram, pixel 461 located in row 1, column 1 is denoted as pixel 461[1, 1], pixel 461 located in row 1, column n is denoted as pixel 461[1, n], pixel 461 located in row m, column 1 is denoted as pixel 461[m, 1], and pixel 461 located in row m, column n is denoted as pixel 461[m, n]. Note that sometimes pixel 461 located in row u, column v (where u is an integer greater than or equal to 1 and less than or equal to m, and v is an integer greater than or equal to 1 and less than or equal to n) is denoted as pixel 461[u, v].

[0508] Furthermore, the display device 460 includes m wirings 465 arranged in a parallel manner, and their potentials are controlled by circuitry in the first driving circuit section 463. The potential of one wiring 465 is supplied to n pixels 461 arranged in the row direction. Note that, depending on the structure of the pixels 461, one wiring 465 may also include multiple wirings. Figure 23B The display device 460A shown illustrates a structural example of a wiring 465 including two wirings.

[0509] Furthermore, the display device 460 includes n wirings 466 arranged in a parallel manner, and their potentials are controlled by circuitry in the second driving circuit section 464. The potential of one wiring 466 is supplied to m pixels 461 arranged in the column direction. Note that, depending on the structure of the pixels 461, one wiring 466 may also include multiple wirings.

[0510] Pixel 461, for example, has the function of writing a data potential to a pixel circuit selected according to the potential of wiring 465 via wiring 466, thereby causing the light-emitting element to emit light at a light intensity corresponding to the data potential.

[0511] A specific example of the pixel circuitry that can be used for pixel 461 will be described later. Note that, as at least part of pixel 461, semiconductor devices such as 470A, which will be described later, can be used.

[0512] The circuit in the first driving circuit section 463 is used, for example, as a scan line driving circuit (sometimes also called a gate line driving circuit, gate driver, scan driver, or row driver).

[0513] The circuitry in the second drive circuit section 464 is used, for example, as a signal line drive circuit (sometimes also called a source line drive circuit, source driver, data driver, or column driver). Furthermore, it may also have the function of converting data (image data) of an image displayed on the display device 460 into data potentials (digital-to-analog conversion).

[0514] In pixel 461, for example, the current flowing through the light-emitting element can be output to the monitoring line. For example, the current output to the monitoring line can be converted into an analog voltage (current-to-voltage conversion) or a digital signal (analog-to-digital conversion) in the second drive circuit section 464 and output to the outside of the display device 460. For example, the analog voltage or the digital signal can be used to perform image data correction (also known as external correction) outside the display device.

[0515] Specific structural examples of the constituent circuits that can be used in the circuits included in the first drive circuit section 463 and the second drive circuit section 464 will be described later. Furthermore, as at least a part of the circuits included in the first drive circuit section 463 and the second drive circuit section 464, for example, the semiconductor device 480 described later can be used.

[0516] In one aspect of the invention, various structures can be used as variations of the display device 460. For example, such as Figures 23C to 23E As shown, the first drive circuit section 463L and the first drive circuit section 463R can also be arranged opposite each other with the display section 462 sandwiched between them.

[0517] Figure 23C The display device 460B shown illustrates a structural example including m wires 465L whose potentials are controlled by circuitry in a first driving circuitry section 463L and m wires 465R whose potentials are controlled by circuitry in a first driving circuitry section 463R. The potentials of one wire 465L and one wire 465R are each supplied to n pixels 461 arranged in the row direction.

[0518] Figure 23DThe illustrated display device 460C shows a structural example of m wirings 465 whose potentials are controlled by both circuits in the first driving circuit section 463L and the first driving circuit section 463R. The potential of one wiring 465 is supplied to n pixels 461 arranged in the row direction. By employing this structure, for example, the load on the substantial wiring (parasitic capacitance and parasitic resistance) can be reduced to... Figure 23B The wiring load of the display device 460A shown is 1 / 4. Therefore, for example, it is possible to achieve high speed, high definition, high resolution, narrow bezel, and large screen of the display device.

[0519] Figure 23E The illustrated display device 460D shows a structural example including m / 2 wirings 465L whose potentials are controlled by circuitry in a first driving circuit section 463L, and m / 2 wirings 465R whose potentials are controlled by circuitry in a first driving circuit section 463R. The potential of one wiring 465L is supplied to n pixels 461 arranged along the row direction in odd-numbered rows. The potential of one wiring 465R is supplied to n pixels 461 arranged along the row direction in even-numbered rows. By employing this structure, for example, the number of stages in the shift register can be reduced to 1 / 2. Therefore, for example, it is possible to achieve higher speeds, higher resolutions, higher resolutions, narrower bezels, and larger screens in the display device.

[0520] Furthermore, although not shown, the two second drive circuit sections 464 may be configured, for example, with the display section 462 sandwiched between them and facing each other.

[0521] In one embodiment of the present invention, in addition to the display devices 460 with the various structures described above, a sensor unit may also be provided in a manner that overlaps with the display unit 462 when viewed from above. This sensor unit may, for example, have functions such as a touch sensor, a non-touch sensor, or a fingerprint sensor. Furthermore, these sensors may be, for example, capacitive or optical sensors.

[0522] 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, for example, include circuitry that functions to drive the sensor unit. Additionally, the second drive circuit unit 464 may, for example, include circuitry that functions to output the signal detected by the sensor unit to an external part of the display device.

[0523] [Peripheral drive circuit]

[0524] Next, examples of the structures of each constituent circuit that can be used in the peripheral drive circuit of the display device 460 will be described.

[0525] Note that in this specification and the like, the circuits in the first drive circuit section 463 and the second drive circuit section 464 included in the display device 460 are sometimes collectively referred to as "peripheral drive circuits".

[0526] The peripheral drive circuit can be constructed using various constituent circuits. Examples of such constituent circuits include shift register circuits, flip-flop circuits, latch circuits, buffer circuits, inverter circuits, and level shifter circuits. Furthermore, examples include multiplexer circuits, demultiplexer circuits, source follower circuits, source-to-ground amplifier circuits, sample-and-hold circuits, and switching circuits (e.g., transmission gates and analog switches). Additionally, examples include current-to-voltage converter circuits, analog-to-digital converter circuits, digital-to-analog converter circuits, operational amplifier circuits, comparator circuits, transmission transistor logic circuits, encoder circuits, decoder circuits, and gate circuits (e.g., AND circuits, OR circuits, and NOT circuits). Furthermore, circuits combining these circuits can also be used. These constituent circuits can be constructed using transistors and capacitors, for example.

[0527] In one embodiment of the present invention, at least a portion of the semiconductor device 100A, semiconductor device 100B, driving circuit 110A, driving circuit 110B, driving circuit 116A, and driving circuit 117A shown in Embodiment 1 can be used in the peripheral driving circuit (first driving circuit section 463 and second driving circuit section 464) shown in this embodiment. For example, when using driving circuit 110A, this driving circuit can also be provided in the first driving circuit section 463 and the wiring OUT31 can be electrically connected to the wiring 465. In this case, the first driving circuit section 463 includes m driving circuits 110A, and the wiring OUT31 of each driving circuit 110A is electrically connected to n pixels 461 through the wiring 465. In addition, for example, when using driving circuit 110B, this driving circuit can also be provided in the first driving circuit section 463 and the wiring OUT31 can be electrically connected to the wiring 465. In this configuration, the first driving circuit section 463 includes m driving circuits 110B, and the wiring OUT31 of each driving circuit 110B is electrically connected to n pixels 461 via wiring 465. Alternatively, for example, when using driving circuit 116A, this driving circuit can also be included in the first driving circuit section 463, and wiring OUT61 can be electrically connected to wiring 465. In this configuration, the first driving circuit section 463 includes m driving circuits 116A, and the wiring OUT61 of each driving circuit 116A is electrically connected to n pixels 461 via wiring 465. Alternatively, for example, when using driving circuit 117A, this driving circuit can also be included in the first driving circuit section 463, and wiring OUT71 can be electrically connected to wiring 465. In this configuration, the first driving circuit section 463 includes m driving circuits 117A, and the wiring OUT71 of each driving circuit 117A is electrically connected to n pixels 461 via wiring 465. Thus, by using drive circuits 110A and 110B, the reliability of the display device can be improved.

[0528] Furthermore, in one aspect of the present invention, various transistors can be used as the transistors constituting the peripheral drive circuit. For example, a vertical transistor such as the transistor 300 shown in Embodiment 2 above can be used as part or all of the transistors constituting the peripheral drive circuit.

[0529] By using vertical transistors as part or all of the transistors constituting the peripheral driving circuit, the area occupied by buffer circuits and the like constituting the circuits in the first driving circuit section 463 can be reduced, for example. This allows for, for example, a narrower bezel in the display device. Furthermore, for example, the area occupied by demultiplexers and source followers constituting the circuits in the second driving circuit section 464 can be reduced. This allows for higher resolution and higher definition in the display device.

[0530] As part or all of the transistors constituting the peripheral drive circuit, an OS transistor can be used, for example. Alternatively, both an OS transistor and a Si transistor can be used, for example.

[0531] As mentioned above, OS transistors have the characteristic of extremely low off-state current. Furthermore, they exhibit the characteristic that the off-state current hardly increases even at high temperatures, and the on-state current does not easily decrease. Si transistors operate faster than OS transistors. Moreover, CMOS circuits (e.g., complementary circuits, CMOS logic gates, or CMOS logic circuits) can be constructed, for example, by electrically connecting the gate of an n-channel transistor to the gate of a p-channel transistor.

[0532] Therefore, OS transistors and Si transistors can be appropriately used as transistors to form the peripheral driving circuit.

[0533] [Shift Register]

[0534] Figures 24A to 24E This is a circuit diagram illustrating an example of the structure of a semiconductor device that can be used in a peripheral drive circuit. This semiconductor device can, for example, be used as part of a scan line drive circuit (such as the circuit in the first drive circuit section 463). Furthermore, it can, for example, be used as part of a shift register.

[0535] Figure 24A The illustrated semiconductor device 480 includes m register sections 481 and m buffer sections 482. Furthermore, the semiconductor device 480 is connected to m wirings GL1 and m wirings GL2. The m register sections 481 are electrically connected to each other via each of the m wirings SR. Figure 24A The abstract shows a portion of the semiconductor device 480, including register sections 481_u to 481_u+2, buffer sections 482_u to 482_u+2, wiring SR_u-1 to SR_u+4, wiring GLa_u to GLa_u+2, and wiring GLb_u to GLb_u+2. Note that m is an integer greater than or equal to 2. Furthermore, u is an integer greater than or equal to 1 and less than or equal to m.

[0536] Figure 24B This is a circuit diagram illustrating an example of the structure of register section 481 and buffer section 482. Figure 24CThis corresponds to the circuit blocks of register section 481 and buffer section 482. Register section 481 can be used as each of register sections 481_1 to 481_m. Buffer section 482 can be used as each of buffer sections 482_1 to 482_m. That is, for example, in register section 481_u, wiring IN81 is electrically connected to wiring SR_u-1, wiring IN82 is electrically connected to wiring SR_u+2, and wiring OUT81 is electrically connected to wiring SR_u. Furthermore, for example, in buffer section 482_u, wiring OUT8A is electrically connected to wiring GLa_u, and wiring OUT8B is electrically connected to wiring GLb_u. Note that in... Figure 24A and Figure 24C The descriptions of wiring IN81, wiring IN8A, wiring IN8B, wiring VLD, and wiring VLS are omitted. Note that register sections 481_1 to 481_u-1 and register sections 481_u+1 to 481_m are also described in the same way. Similarly, buffer sections 482_1 to 482_u-1 and buffer sections 482_u+1 to 482_m are also described in the same way.

[0537] In other words, in semiconductor device 480, wiring OUT81 in register section 481_u-1 is electrically connected to wiring IN81 in register section 481_u via wiring SR_u-1, and wiring OUT81 in register section 481_u is electrically connected to wiring IN81 in register section 481_u+1 via wiring SR_u. With this structure, each of register sections 481_1 to 481_m is sequentially selected, and in buffer section 482_u electrically connected to the selected register section 481_u, the desired potential can be supplied to wiring GLa_u and wiring GLb_u respectively. Note that in buffer section 482_u of semiconductor device 480 electrically connected to the unselected register section 481_u, both wiring GLa_u and wiring GLb_u are supplied with the potential of wiring VLS.

[0538] Figure 24BThe register section 481 shown includes transistors M81, M82, M83, M84, M85, and M86. Transistor M81 functions to maintain a conducting or non-conducting state between wiring VLD and wiring NL81 based on the potential of wiring IN81. Transistor M82 functions to maintain a conducting or non-conducting state between wiring VLD and wiring NL82 based on the potential of wiring IN82. Transistor M83 functions to maintain a conducting or non-conducting state between wiring VLS and wiring NL81 based on the potential of wiring NL82. Transistor M84 functions to maintain a conducting or non-conducting state between wiring VLS and wiring NL82 based on the potential of wiring IN81. Transistor M85 functions to maintain a conducting or non-conducting state between wiring IN83 and wiring OUT81 based on the potential of wiring NL81. Transistor M86 functions to maintain a conducting or non-conducting state between wiring VLS and wiring OUT81 based on the potential of wiring NL82.

[0539] also, Figure 24B The buffer unit 482 shown includes transistors M8A, M8B, M8C, and M8D. Transistor M8A functions to maintain a conducting or non-conducting state between wiring IN8A and wiring OUT8A based on the potential of wiring NL81. Transistor M8B functions to maintain a conducting or non-conducting state between wiring IN8B and wiring OUT8B based on the potential of wiring NL81. Transistor M8C functions to maintain a conducting or non-conducting state between wiring VLS and wiring OUT8A based on the potential of wiring NL82. Transistor M8D functions to maintain a conducting or non-conducting state between wiring VLS and wiring OUT8B based on the potential of wiring NL82.

[0540] Figure 24D This is an explanation Figure 24B Timing diagram of an example of the operation of register section 481 and buffer section 482 shown.

[0541] In the following operating instructions, wiring VLD is supplied with potential H, and wiring VLS is supplied with potential L. Additionally, wiring IN81, wiring IN82, wiring IN83, wiring IN8A, and wiring IN8B are supplied with potential H or potential L. Note that potential H is higher than potential L. For example, the difference between potential H and potential L may be greater than the transistor's threshold voltage.

[0542] Figure 24DThe timing diagram shown illustrates the potentials (potential H or potential L) supplied to wiring IN81, wiring IN82, wiring IN83, wiring IN8A, and wiring IN8B during each period of operation (period T81 to period T83). Additionally, the potential changes for wiring NL81, wiring NL82, wiring OUT81, wiring OUT8A, and wiring OUT8B are shown.

[0543] During period T81, wiring IN81 and IN82 are supplied with potential L. Additionally, wiring NL82 is supplied with potential H. Therefore, wiring NL81 is supplied with potential L. At this time, transistors M85, M8A, and M8B are all in the off state (non-conducting state), while transistors M86, M8C, and M8D are all in the on state (conducting state). Therefore, potential L is supplied to wiring OUT81, OUT8A, and OUT8B respectively, regardless of the individual potentials (potential H or potential L) of wiring IN83, IN8A, and IN8B. Note that in the following operational description, the potentials of the wirings are considered to remain constant from the previous period unless otherwise specified.

[0544] During T82, because wiring IN81 is supplied with potential H, the potential of wiring NL82 becomes potential L, and the potential of wiring NL81 becomes potential H. At this time, transistors M85, M8A, and M8B are all turned on, while transistors M86, M8C, and M8D are all turned off. Therefore, the potentials (potentials H or L) of wiring IN83, IN8A, and IN8B are supplied to wiring OUT81, OUT8A, and OUT8B respectively through transistors M85, M8A, and M8B. Note that even if wiring IN81 is subsequently supplied with potential L, the potentials of wiring NL82 and NL81 are maintained.

[0545] During T83, since wiring IN82 is supplied with potential H, the potential of wiring NL82 becomes potential H, and the potential of wiring NL81 becomes potential L. At this time, transistors M85, M8A, and M8B are all turned off, while transistors M86, M8C, and M8D are all turned on. Therefore, potential L is supplied to wirings OUT81, OUT8A, and OUT8B respectively, regardless of their individual potentials (potential H or potential L). Note that even if wiring IN82 is subsequently supplied with potential L, the potentials of wiring NL82 and NL81 are maintained.

[0546] Figure 24E This is a circuit diagram illustrating a modified example of the register section 481 and the buffer section 482. Figure 24E The register section 481a and buffer section 482a shown differ from register section 481 and buffer section 482 in that they include a bootstrap circuit. That is, register section 481a includes transistor M87 and capacitor C81 in addition to register section 481, and buffer section 482a includes transistor M8E, transistor M8F, capacitor C8A, and capacitor C8B in addition to buffer section 482. Note that capacitors C81, C8A, and C8B are sometimes referred to as bootstrap capacitors.

[0547] The gate of transistor M87 is electrically connected to wiring VLD. The gate of transistor M85 is electrically connected to wiring NL81 through the source and drain of transistor M87. In addition, the gate of transistor M85 is electrically connected to wiring OUT81 through capacitor C81.

[0548] The gate of transistor M8E is electrically connected to wiring VLD. The gate of transistor M8A is electrically connected to wiring NL81 through the source and drain of transistor M8E. In addition, the gate of transistor M8A is electrically connected to wiring OUT8A through capacitor C8A.

[0549] The gate of transistor M8F is electrically connected to wiring VLD. The gate of transistor M8B is electrically connected to wiring NL81 through the source and drain of transistor M8F. Furthermore, the gate of transistor M8B is electrically connected to wiring OUT8B through capacitor C8B.

[0550] Here, in register section 481, when potential H is transferred from wiring IN83 to wiring OUT81, the potential of transistor M85 drops due to the threshold voltage. Therefore, by employing a bootstrap circuit as in register section 481a, transistor M85 can be kept in the on state by utilizing the capacitive coupling of the bootstrap capacitor. Thus, potential H can be supplied to wiring OUT81 without the threshold voltage causing a potential drop.

[0551] Similarly, in register section 482, when potential H is transferred from wiring IN8A to wiring OUT8A, the potential of transistor M8A decreases due to the threshold voltage, and when potential H is transferred from wiring IN8B to wiring OUT8B, the potential of transistor M8B decreases due to the threshold voltage. Therefore, by employing a bootstrap circuit as in register section 482a, both transistors M8A and M8B can be kept in the on state by utilizing the capacitive coupling of the bootstrap capacitor. Thus, potential H can be transferred to wiring OUT8A and wiring OUT8B without the threshold voltage causing a potential drop.

[0552] Furthermore, in one embodiment of the present invention, at least a portion of the semiconductor devices 100A and 100B shown in Embodiment 1 can be used in the register section 481 and buffer section 482 included in the semiconductor device 480. This improves the reliability of the display device including the semiconductor device.

[0553] [Pixel Circuit]

[0554] Next, an example of the structure of the pixel circuit that can be used for the pixel 461 in the display device 460 will be described.

[0555] Figure 25 This is a circuit diagram illustrating an example of the structure of a semiconductor device that can be used in pixel 461.

[0556] like Figure 25 As shown, the semiconductor device 470A includes a pixel circuit 471A and a light-emitting element D51. The pixel circuit 471A includes transistors M51, M52, and M53, and a capacitor C51.

[0557] The gate of transistor M52 is electrically connected via wiring NL52 to one of the source and drain of transistor M51 and one terminal of capacitor C51. One of the source and drain of transistor M52 is electrically connected via wiring NL51 to the other terminal of capacitor C51, one of the source and drain of transistor M53, and one terminal (e.g., the anode terminal) of light-emitting element D51.

[0558] One of the source and drain terminals of transistor M52 is electrically connected to wiring ANO. The other terminal of the light-emitting element D51 (e.g., the cathode terminal) is electrically connected to wiring CATHO. The other of the source and drain terminals of transistor M51 is electrically connected to wiring DL. The other of the source and drain terminals of transistor M53 is electrically connected to wiring VL0. The gates of transistors M51 and M53 are electrically connected to wiring GLa.

[0559] The light-emitting element D51 emits light with a light intensity corresponding to the amount of current flowing through it. For example, an organic EL element can be used as the light-emitting element D51.

[0560] Transistor M52 can change its drain current according to the potential supplied to the gate. Therefore, in pixel circuit 471A, transistor M52 has the function of controlling the amount of current flowing through light-emitting element D51. That is, transistor M52 has the function of controlling the light-emitting intensity of light-emitting element D51. In this specification, transistors having functions like transistor M52 are sometimes referred to as "driving transistors".

[0561] Transistor M51 functions to either conduct or deconduct the gate of transistor M52 with connection DL (acting as a switch). Transistor M53 functions to either conduct or deconduct one of the source and drain of transistor M52 with connection VL0 (acting as a switch). Capacitor C51, for example, functions to maintain the potential difference (voltage) between one of the source and drain of transistor M52 and the gate of transistor M52 when connection NL52 is in a floating state.

[0562] Sometimes the wiring GLa is referred to as a gate line, scan line, or select line, etc. Sometimes the wiring DL is referred to as a source line, data line, or signal line, etc.

[0563] Additionally, in the semiconductor device 470A, the current flowing through transistor M52 or the current flowing through light-emitting element D51 can be output to wiring VL0 via transistor M53. Therefore, wiring VL0 is sometimes referred to as the monitoring line.

[0564] In one aspect of the invention, various transistors can be used as transistors (transistor M51 to transistor M53) constituting pixel circuit 471A.

[0565] For example, an n-channel transistor can be used as part or all of the transistors constituting the pixel circuit 471A. Alternatively, a p-channel transistor can be used, for example.

[0566] Furthermore, for example, transistors including a back gate can be used as part or all of the transistors constituting pixel circuit 471A.

[0567] Figure 26 This is a circuit diagram illustrating an example of a transistor structure (transistors M51 to M53) constituting pixel circuit 471A, using transistors including a back gate. In each of transistors M51 to M53, the back gate of each transistor is electrically connected to the gate. Thus, in transistors including a back gate, the same potential as the gate is supplied to the back gate, thereby reducing the on-state resistance.

[0568] Note that in a transistor including a back gate, the potential supplied to the back gate is not limited to the same potential as the gate. For example, by supplying the back gate with the same potential as the source, the electric field generated outside the transistor is less likely to affect the channel formation region, thus stabilizing the electrical characteristics and improving reliability. For example, by supplying an arbitrary potential to the back gate, the threshold voltage can be changed. Note that the potential supplied to the back gate is not limited to a fixed potential. Furthermore, the potential supplied to the back gate can be different or the same on a per-transistor basis.

[0569] Furthermore, for example, a vertical transistor such as the transistor 300 shown in Embodiment 2 above can be used as part or all of the transistors constituting the pixel circuit 471A. Furthermore, for example, a planar transistor such as the transistor 200 shown in Embodiment 2 above can be used.

[0570] In one embodiment of the invention, vertical transistors are preferably used as part or all of the transistors constituting pixel circuit 471A. In particular, vertical transistors are preferably used as transistors (transistor M51 and transistor M53) used as switches.

[0571] Therefore, by using vertical transistors in the pixel circuit, the sharpness (also known as pixel density) of the display device using the pixel circuit can be improved, for example. Additionally, for example, a striped arrangement can be used instead of a Pentile arrangement for the pixel arrangement without reducing the sharpness of the display device. Furthermore, for example, an internal correction circuit, which will be described later, can be installed without reducing the sharpness of the display device.

[0572] Note that, for example, a transistor with high saturation can also be used as the driving transistor (transistor M52). For example, a transistor with a large channel length can also be used. Furthermore, for example, a planar transistor can also be used.

[0573] Alternatively, in one embodiment of the present invention, an OS transistor with extremely low off-state current can also be used as the transistor constituting the pixel circuit 471A.

[0574] For example, in the transistors that constitute the pixel circuit 471A, an OS transistor is used as a switch (transistor M51 and transistor M53), thereby maintaining the charge stored in capacitor C51 for a long time.

[0575] Therefore, for example, in a display device using this pixel circuit, when displaying a static image that does not require rewriting on a frame-by-frame basis, the image can continue to be displayed even if the operation of the peripheral drive circuit driving the pixel circuit is stopped. In this specification and the like, the driving method of stopping the operation of the peripheral drive circuit when displaying a static image is also referred to as "idle stop driving." By performing idle stop driving, the power consumption of the display device can be reduced.

[0576] Note that in one embodiment of the invention, the structure of the pixel circuit 471A is not limited to a structure using an OS transistor, and can also employ a structure using multiple transistors containing different semiconductor materials. For example, the pixel circuit 471A can also be constructed from LTPO (i.e., both an LTPS transistor and an OS transistor).

[0577] For example, in the transistors constituting the pixel circuit 471A, an OS transistor can be used as a switch transistor (transistor M51 and transistor M53), and an LTPS transistor can be used as a drive transistor (transistor M52). When the pixel circuit 471A is composed of both the LTPS transistor and the OS transistor, the power consumption of the display device using the pixel circuit can be reduced and the driving capability can be improved.

[0578] When the pixel circuit 471A has a structure using multiple transistors containing different semiconductor materials, the transistors can be disposed on different layers depending on the type of transistor. For example, when the pixel circuit 471A is composed of Si transistors and OS transistors, layers including Si transistors and layers including OS transistors can be stacked. By adopting this structure, the area occupied by the pixel circuit 471A can be reduced.

[0579] Regarding the operation of semiconductor device 470A, a potential H is first supplied to wiring GLa, thereby supplying a data potential from wiring DL to wiring NL52, and a potential from wiring VL0 to wiring NL51. In other words, a voltage corresponding to the data potential is applied as the gate voltage of transistor M52.

[0580] Next, the wiring GLa is supplied with a potential L, thereby allowing a current corresponding to the gate voltage applied to transistor M52 to flow through the light-emitting element D51. The light-emitting element D51 then emits light with a light intensity corresponding to this current.

[0581] In one embodiment of the present invention, the semiconductor device that can be used for pixel 461 is not limited to the structure of semiconductor device 470A. A modified example of this semiconductor device will be described below.

[0582] Figure 27 This is a circuit diagram of semiconductor device 470B, illustrating a variation of semiconductor device 470A. Semiconductor device 470B includes pixel circuit 471B instead of pixel circuit 471A. The difference between pixel circuit 471B and pixel circuit 471A is that pixel circuit 471B includes transistors M54, M55, and M56 and capacitor C52 instead of transistor M53 and capacitor C51. Pixel circuit 471B includes an internal correction circuit.

[0583] The gate of transistor M52 is electrically connected via wiring NL52 to one of the source and drain of transistor M55 and one of the source and drain of transistor M56. One of the source and drain of transistor M51 is electrically connected via wiring NL53 to the other of the source and drain of transistor M56 and one terminal of capacitor C52. One of the source and drain of transistor M52 is electrically connected via wiring NL51 to the other terminal of capacitor C52 and one of the source and drain of transistor M54. The other of the source and drain of transistor M54 is electrically connected to one terminal of the light-emitting element D51.

[0584] The source and drain of transistor M55 are electrically connected to wiring VL1. The gate of transistor M55 is electrically connected to wiring GLa. The gate of transistor M56 is electrically connected to wiring GLb. The gate of transistor M54 is electrically connected to wiring Glc.

[0585] Transistor M55 functions to either conduct or de-conduct between the gate of transistor M52 and wiring VL1 (acting as a switch). Transistor M56 functions to either conduct or de-conduct between the gate of transistor M52 and one of the source and drain of transistor M51 (acting as a switch). Transistor M54 functions to either conduct or de-conduct between one of the source and drain of transistor M52 and a terminal of light-emitting element D51 (acting as a switch). Capacitor C52, for example, functions to maintain the potential difference (voltage) between one of the source and drain of transistor M52 and one of the source and drain of transistor M51 when wiring NL53 is in a floating state.

[0586] Sometimes the wiring GLb and wiring GLc are referred to as gate lines, scan lines, or select lines, for example.

[0587] Regarding the operation of semiconductor device 470B, firstly, wiring GLa and GLb are supplied with potential L, and wiring GLc is supplied with potential H. Then, wiring GLa is supplied with potential H. Next, wiring GLc is supplied with potential L. Then, wiring GLa is supplied with potential L. Through the above series of operations, a data potential is supplied from wiring DL to wiring NL53, and the voltage corresponding to the threshold voltage of transistor M52 is maintained in capacitor C52.

[0588] Next, wirings GLb and Glc are supplied with a potential H, thereby applying a voltage held in capacitor C52 as the gate voltage of transistor M52, and a current corresponding to this voltage flows through light-emitting element D51. Light-emitting element D51 then emits light with a luminous intensity corresponding to this current. At this time, a voltage independent of the threshold voltage of transistor M52 is applied as the gate voltage of transistor M52. Therefore, a current independent of the threshold voltage of transistor M52 flows through light-emitting element D51.

[0589] Figure 28 This is a circuit diagram of semiconductor device 470C, illustrating a variation of semiconductor device 470A. Semiconductor device 470C includes pixel circuit 471C instead of pixel circuit 471A. Pixel circuit 471C includes, in addition to pixel circuit 471A, transistors M54, M57, and M58, and capacitor C53. Furthermore, transistor M52 includes a back gate, unlike pixel circuit 471A. Pixel circuit 471C includes internal correction circuitry, different from pixel circuit 471B.

[0590] The gate of transistor M52 is electrically connected via wiring NL52 to one of the source and drain terminals of transistor M51, one terminal of capacitor C51, and one of the source and drain terminals of transistor M57. The back gate of transistor M52 is electrically connected via wiring NL54 to one terminal of capacitor C53 and one of the source and drain terminals of transistor M58. One of the source and drain terminals of transistor M52 is electrically connected via wiring NL51 to the other terminal of capacitor C51, the other terminal of capacitor C53, the other of the source and drain terminals of transistor M57, one of the source and drain terminals of transistor M53, and one of the source and drain terminals of transistor M54. The other of the source and drain terminals of transistor M54 is electrically connected to one terminal of the light-emitting element D51.

[0591] The source and drain of transistor M58 are electrically connected to wiring VL2. The gates of transistors M57 and M58 are electrically connected to wiring GLb. The gate of transistor M54 is electrically connected to wiring GLC.

[0592] The threshold voltage of transistor M52 can be changed according to the potential supplied to the back gate.

[0593] Transistor M57 functions to either conduct or deconduct between the gate of transistor M52 and one of its source and drain (acting as a switch). Transistor M58 functions to either conduct or deconduct between the gate of transistor M52 and wiring VL2 (acting as a switch). Transistor M54 functions to either conduct or deconduct between one of the source and drain of transistor M52 and a terminal of the light-emitting element D51 (acting as a switch). Capacitor C53, for example, functions to maintain the potential difference (voltage) between one of the source and drain of transistor M52 and its back gate when wiring NL54 is in a floating state.

[0594] Sometimes the wiring GLb and wiring GLc are referred to as gate lines, scan lines, or select lines, for example.

[0595] Regarding the operation of semiconductor device 470C, firstly, wiring GLa is supplied with potential L, and wirings GLb and GLc are supplied with potential H. Next, wiring GLc is supplied with potential L. Then, wiring GLb is supplied with potential L. Through this series of operations, the threshold voltage of transistor M52 is corrected to 0V and maintained in capacitor C53.

[0596] Next, a potential H is supplied to wiring GLa, thereby supplying a data potential from wiring DL to wiring NL52 and a potential from wiring VL0 to wiring NL51. In other words, a voltage corresponding to the data potential is applied as the gate voltage of transistor M52.

[0597] Next, wiring GLa is supplied with a potential L, and wiring GLc is supplied with a potential H, thereby allowing a current corresponding to the gate voltage applied to transistor M52 to flow through the light-emitting element D51. The light-emitting element D51 then emits light with an intensity corresponding to this current. At this time, a voltage is applied as the back gate voltage of transistor M52 to correct the threshold voltage of transistor M52 to 0V. Therefore, a current independent of the threshold voltage of transistor M52 flows through the light-emitting element D51.

[0598] Figure 29 This is a circuit diagram of semiconductor device 470D, a variation of semiconductor device 470C. Semiconductor device 470D includes pixel circuit 471D instead of pixel circuit 471C. Pixel circuit 471D differs from pixel circuit 471C in that it does not include transistor M53.

[0599] In the operation of semiconductor device 470D, the following structure can also be adopted: when a data potential is supplied from wiring DL to wiring NL52, for example, by turning on transistor M54, the potential of wiring NL51 increases by a potential equivalent to the voltage drop of light-emitting element D51. Semiconductor device 470D may also exclude wiring VL0. This reduces the area occupied by pixel circuit 471D.

[0600] Figure 30 This is a circuit diagram of semiconductor device 470E, a variant example of semiconductor device 470C. Semiconductor device 470E includes pixel circuit 471E instead of pixel circuit 471C. Pixel circuit 471E differs from pixel circuit 471C in that it does not include transistor M54. Therefore, one of the source and drain of transistor M52 is electrically connected to a terminal of light-emitting element D51.

[0601] In the operation of semiconductor device 470E, the following structure can also be adopted: when the threshold voltage of transistor M52 is corrected to 0V and the back gate voltage is maintained in capacitor C53, for example, by supplying the wiring CATHO with the same potential as wiring ANO, current is not allowed to flow through the light-emitting element D51. Semiconductor device 470E may also exclude wiring GLc. Therefore, the occupied area of ​​pixel circuit 471E can be reduced.

[0602] Figure 31 This is a circuit diagram of semiconductor device 470F, which is a variation of semiconductor device 470B. Semiconductor device 470F includes pixel circuit 471F instead of pixel circuit 471B. Pixel circuit 471F includes, in addition to pixel circuit 471B, transistor M59 and capacitor C54.

[0603] The gate of transistor M54 is electrically connected to one terminal of capacitor C54 and one of the source and drain terminals of transistor M59 via wiring NL55. The other of the source and drain terminals of transistor M54 is electrically connected to one terminal of light-emitting element D51 and the other terminal of capacitor C54.

[0604] The source and drain of transistor M59 are electrically connected to wiring GLC. The gate of transistor M59 is electrically connected to wiring VL3.

[0605] Transistor M59 functions to keep the gate of transistor M54 in a conducting or non-conducting state with respect to wiring GLC (acting as a switch). Capacitor C54, for example, functions to maintain the potential difference (voltage) between the source and drain of transistor M54 and the gate of transistor M54 when wiring NL55 is in a floating state.

[0606] In the operation of semiconductor device 470F, when a current corresponding to the gate voltage applied to transistor M52 flows through light-emitting element D51, the potential of one terminal of light-emitting element D51 (i.e., the other of the source and drain terminals of transistor M54) rises. Consequently, due to the capacitive coupling through capacitor C54, the potential of wiring NL55 (i.e., the gate of transistor M54) also rises. Therefore, transistor M54 can be reliably turned on. Thus, a stable current can be supplied to light-emitting element D51. Note that capacitor C54 is sometimes referred to as a bootstrap capacitor.

[0607] Figure 32 This is a circuit diagram of semiconductor device 470G, illustrating a variation of semiconductor device 470C. Semiconductor device 470G includes pixel circuit 471G instead of pixel circuit 471C. Pixel circuit 471G includes transistor M59 and capacitor C54 in addition to pixel circuit 471C. That is, pixel circuit 471G has a structure combining the internal correction circuit of pixel circuit 471C and the bootstrap capacitor of pixel circuit 471F.

[0608] Figure 33 This is a circuit diagram illustrating semiconductor device 470H. Semiconductor device 470H includes pixel circuit 471H and liquid crystal element D52. Pixel circuit 471H includes transistor M51 and capacitor C55.

[0609] The gate of transistor M51 is electrically connected to wiring GLa. One of the source and drain terminals of transistor M51 is electrically connected to one terminal of capacitor C55 and one terminal of liquid crystal element D52 via wiring NL56. The other of the source and drain terminals of transistor M51 is electrically connected to wiring DL. The other terminal of capacitor C55 is electrically connected to wiring CS. The other terminal of liquid crystal element D52 is electrically connected to wiring COM.

[0610] The light transmittance of the liquid crystal element D52 varies according to the potential difference (voltage) between a pair of terminals (between one terminal and the other terminal).

[0611] Transistor M51 functions to keep one terminal of capacitor C55 in a conducting or non-conducting state with wiring DL (acting as a switch). Capacitor C55, for example, functions to maintain the potential difference (voltage) between a pair of terminals of liquid crystal element D52 when wiring NL56 is in a floating state.

[0612] Figure 34This is a circuit diagram of semiconductor device 470J, which is a modified example of semiconductor device 470A. Semiconductor device 470J includes pixel circuit 471J instead of pixel circuit 471A. In addition to pixel circuit 471A, pixel circuit 471J also includes transistor M5A, transistor M5B, and capacitor C5A.

[0613] The gate of transistor M5B is electrically connected to one of the source and drain terminals of transistor M5A and one terminal of capacitor C5A via wiring NL5A. One of the source and drain terminals of transistor M5B is electrically connected to the gate of transistor M52, one of the source and drain terminals of transistor M51, and one terminal of capacitor C51 via wiring NL52.

[0614] One of the source and drain terminals of transistor M5A is electrically connected to wiring DLW. The other of the source and drain terminals of transistor M5B is electrically connected to wiring VLW. The other terminal of capacitor C5A is electrically connected to wiring SWEP. The gate of transistor M51 is electrically connected to wiring GLb but not to wiring GLa. The gate of transistor M53 is electrically connected to wiring GLc but not to wiring GLa. The gate of transistor M5A is electrically connected to wiring GLa.

[0615] The pixel circuit 471J has the function of performing PWM control. For example, PWM control data potential is supplied from wiring DLW to wiring NL5A through transistor M5A, and a triangular wave or sawtooth wave is supplied to wiring SWEP, thereby performing PWM control. Note that, for example, when using a Micro LED or the like as the light-emitting element D51, PWM control is preferred from the viewpoint of stabilizing the emission wavelength.

[0616] Figure 35 This is a circuit diagram showing a modified example of semiconductor device 470B. Figure 35 The semiconductor device 470B1 shown includes a pixel circuit 471B1 instead of a pixel circuit 471B. The pixel circuit 471B1 is a structural example in which the switching part 101A included in the semiconductor device 100A and the switching part 101B included in the semiconductor device 100B shown in Embodiment 1 are used in the pixel circuit 471B.

[0617] Here, it is shown that Figure 3A The switch 101A shown is used for transistors M54 and M56, to... Figure 6A The switch 101B shown is used for transistor M55, and will Figure 3B The shown switch section 101A is a structural example used for transistor M51. Therefore, Figure 35The following structure is shown: transistor M51 is replaced by switch section 101A_1, transistor M54 is replaced by switch section 101A_4, transistor M55 is replaced by switch section 101B_5, and transistor M56 is replaced by switch section 101A_6. That is, transistors M51a, M54a, and M56a are equivalent to transistor M11, and transistors M51b, M54b, and M56b are equivalent to transistor M12. Furthermore, transistor M55a is equivalent to transistor M21, and transistor M55b is equivalent to transistor M22. Note that... Figure 35 The structure shown is just an example. The transistors that are at least part of the pixel circuit 471B1 can be switching units 101A and 101B, etc.

[0618] In the pixel circuit 471B1, transistors M54 and M55 are sometimes subjected to high drain voltages, so switching sections 101A and 101B can also be used. Furthermore, since transistor M54 is the path for the current flowing through the light-emitting element D51, the on-state current can also be increased. Therefore, transistor M54 can also have… Figure 3A The structure is similar to that of the switch section 101A shown. Furthermore, the transistor M54 remains in the on-state for a relatively long period, continuously receiving a positive gate bias. Therefore, it is also possible to employ... Figure 3B The switch section 101A shown or Figure 1A The switch section 101A shown has the same structure. Furthermore, the source or drain function of transistor M51 switches according to the data potential supplied to the wiring DL. Therefore, transistor M51 can also have... Figure 3B The switch section 101A shown has the same structure. Additionally, although not shown, the transistor M52 may also have... Figure 6B The switch section 101B shown has a structure that can sometimes reduce not only the drain voltage of transistor M52 but also improve saturation. Thus, by using switch sections 101A and 101B, the reliability of pixel circuit 471B1 and the display device using that pixel circuit can be improved.

[0619] Figure 36 This is a circuit diagram showing a modified example of semiconductor device 470C. Figure 36 The semiconductor device 470C1 shown includes a pixel circuit 471C1 instead of a pixel circuit 471C. The pixel circuit 471C1 is a structural example in which the switching unit 101A included in the semiconductor device 100A and the switching unit 101B included in the semiconductor device 100B shown in Embodiment 1 are used in the pixel circuit 471C.

[0620] Here, it is shown that Figure 3AThe switch 101A shown is used for transistors M53, M54, and M57 to... Figure 6A The switch 101B shown is used for transistor M58, which will... Figure 3B The shown switch section 101A is a structural example used for transistor M51. Therefore, in Figure 36 The diagram shows the following structure: transistor M51 is replaced by switch 101A_1, transistor M53 by switch 101A_3, transistor M54 by switch 101A_4, transistor M57 by switch 101A_7, and transistor M58 by switch 101B_8. That is, transistors M51a, M53a, M54a, and M57a are equivalent to transistor M11, and transistors M51b, M53b, M54b, and M57b are equivalent to transistor M12. Furthermore, transistor M58a is equivalent to transistor M21, and transistor M58b is equivalent to transistor M22. Note that... Figure 36 The structure shown is just an example. The transistors that are at least part of the pixel circuit 471C1 can be switching units 101A and 101B, etc.

[0621] In the pixel circuit 471C1, transistors M53, M54, and M58 are sometimes subjected to high drain voltages, so switching sections 101A and 101B can also be used. Furthermore, since transistor M54 is the path for the current flowing through the light-emitting element D51, the on-state current can also be increased. Therefore, transistor M54 can also have… Figure 3A The switch section 101A shown has the same structure. Furthermore, transistor M53 is also the path for the current flowing through transistor M52 when outputting it to the outside of semiconductor device 470C1, so the on-state current can be increased. Therefore, transistor M53 can also have... Figure 3A The structure is similar to that of the switch section 101A shown. Furthermore, the transistor M54 remains in the on-state for a relatively long period, continuously receiving a positive gate bias. Therefore, it is also possible to employ... Figure 3B The switch section 101A shown or Figure 1A The switch section 101A shown has the same structure. Furthermore, the source or drain function of transistor M51 switches according to the data potential supplied to the wiring DL. Therefore, transistor M51 can also have... Figure 3B The switch section 101A shown has the same structure. Additionally, although not shown, the transistor M52 may also have... Figure 6BThe switch section 101B shown has a structure that can sometimes reduce not only the drain voltage of transistor M52 but also improve saturation. Thus, by using switch sections 101A and 101B, the reliability of pixel circuit 471C1 and the display device using that pixel circuit can be improved.

[0622] Figure 37 This is a circuit diagram showing a modified example of the semiconductor device 470J. Figure 37 The semiconductor device 470J1 shown includes a pixel circuit 471J1 instead of a pixel circuit 471J. The pixel circuit 471J1 is a structural example in which the switching part 101A included in the semiconductor device 100A and the switching part 101B included in the semiconductor device 100B shown in Embodiment 1 are used in the pixel circuit 471J.

[0623] Here, it is shown that Figure 3A The switch 101A shown is used for transistors M53 and M5B and will Figure 3B The shown switch section 101A is a structural example of transistor M51 and transistor M5A. Therefore, in Figure 37 The diagram shows the following structure: transistor M51 is replaced by switch 101A_1, transistor M53 is replaced by switch 101A_3, transistor M5A is replaced by switch 101A_A, and transistor M5B is replaced by switch 101A_B. That is, transistors M51a, M53a, M5Aa, and M5Ba are equivalent to transistor M11, and transistors M51b, M53b, M5Ab, and M5Bb are equivalent to transistor M12. Note that... Figure 36 The structure shown is just an example. The transistors that are at least part of the pixel circuit 471J1 can be switching units 101A and 101B, etc.

[0624] In the pixel circuit 471J1, transistors M53 and M5B are particularly subjected to high drain voltages, so switching section 101A can also be used. Furthermore, since the gate voltage of transistor M5B gradually increases according to the triangular or sawtooth wave supplied to the wiring SWEP, switching section 101A can also be used. Additionally, transistor M53 is also the path for the current flowing through transistor M52 to be output to the outside of semiconductor device 470J1, so the on-state current can also be increased. Therefore, transistor M53 can also have… Figure 3A The switch section 101A shown has the same structure. Furthermore, the source or drain function of transistor M51 switches according to the data potential supplied to the wiring DL. Therefore, transistor M51 can also have... Figure 3BThe switch section 101A shown has the same structure. Furthermore, the source or drain function of transistor M5A switches according to the data potential supplied to the wiring DLW. Therefore, transistor M5A can also have... Figure 3B The switch section 101A shown has the same structure. Additionally, although not shown, the transistor M52 may also have... Figure 6B The switch section 101B shown has a structure that can sometimes reduce not only the drain voltage of transistor M52 but also improve saturation. Thus, by using switch sections 101A and 101B, the reliability of pixel circuit 471J1 and the display device using that pixel circuit can be improved.

[0625] Note that, in one aspect of the present invention, the semiconductor device that can be used for pixel 461 is not limited to the structure described above, and semiconductor devices that appropriately combine the various structures can be employed.

[0626] <Example of cross-sectional structure of a display device>

[0627] Figure 38 This is a cross-sectional view illustrating an example of the cross-sectional structure of a display device according to one aspect of the present invention.

[0628] exist Figure 38 In the display device 490 shown, the structures shown in regions 490a, 490b, and 490c can be used in the display device 400. For example, the structure shown in region 490a can be used in the region where pixel 453 is provided. The structure shown in region 490b can be used in the region where circuit section 454a and circuit section 454b are provided. The structure shown in region 490c can be used in the region where FPC 459 is provided.

[0629] The display device 490 includes a substrate 351 and a substrate 352. Furthermore, an adhesive layer 342 is provided between the substrates 351 and 352. The substrate 352 is positioned opposite the substrate 351 via the adhesive layer 342. Note that region 490c does not include the substrate 352 and the adhesive layer 342.

[0630] An insulating layer 382 is provided on one side of the substrate 351, which is the substrate 352. Transistors and light-emitting elements are disposed on the insulating layer 382.

[0631] Here, as an example, a structure is shown in which the transistor 300 shown in Embodiment 2 is disposed in region 490a and the transistor 200 shown in Embodiment 2 is disposed in region 490b. Furthermore, a conductive layer 384 is disposed in region 490c. The conductive layer 384 can be formed by the same process as conductive layer 204 and conductive layer 304.

[0632] An insulating layer 235 is provided to cover transistors 200 and 300.

[0633] In region 490a, a pixel electrode 311 is provided such that it covers a portion of the insulating layer 235 and has a region that contacts the conductive layer 312b through openings provided in the insulating layers 306, 395 and 235.

[0634] An insulating layer 237 is provided to cover the insulating layer 235 and the pixel electrode 311. The insulating layer 237 has an opening in the area overlapping with the pixel electrode 311 that leads to the pixel electrode 311.

[0635] An EL layer 313 is provided to cover the insulating layer 237 and the pixel electrode 311. A common electrode 315 is provided to cover the EL layer 313. A protective layer 331 is provided to cover the common electrode 315.

[0636] In the opening provided in the insulating layer 237, the pixel electrode 311 is used as one electrode of the light-emitting element 330, the common electrode 315 is used as another electrode, and the EL layer 313 has the function of emitting light.

[0637] A light-shielding layer 317 is provided on one side of substrate 351 of substrate 352.

[0638] In region 490a, the light-shielding layer 317 has an opening that overlaps with the light-emitting element 330. Therefore, light emitted by the light-emitting element 330 exits through the opening in the light-shielding layer 317 to the outside of the display device 490. Figure 38 In the text, the state is indicated by a dashed arrow and the word "light".

[0639] In region 490c, a conductive layer 386 is provided such that it covers a portion of the insulating layer 235 and has a region that contacts the conductive layer 384 through an opening provided in the insulating layer 395 and the insulating layer 235.

[0640] An FPC459 is provided across the connection layer 388 in such a manner that it has a region that overlaps with the conductive layer 386.

[0641] The conductive layer 384 is electrically connected to the FPC459 through the conductive layer 386 and the connecting layer 388.

[0642] As the connecting layer 388, for example, anisotropic conductive film (ACF) or anisotropic conductive paste (ACP) can be used.

[0643] <Example of a light-emitting element's structure>

[0644] In one aspect of the present invention, light-emitting elements having various structures can be used as light-emitting elements included in the display device.

[0645] Figure 39A , Figure 39B , Figure 40A and Figure 40B These are all cross-sectional diagrams illustrating light-emitting elements with various structures.

[0646] [Structure Example 1]

[0647] Figure 39A The display device 490A shown includes light-emitting elements 330R, 330G, and 330B between substrates 351 and 352. Light-emitting element 330R is a display element comprising pixels that emit red light, light-emitting element 330G is a display element comprising pixels that emit green light, and light-emitting element 330B is a display element comprising pixels that emit blue light. Note that when describing the common elements among light-emitting elements 330R, 330G, and 330B, they are sometimes simply referred to as light-emitting element 330.

[0648] Note that in Figure 39A The structure between substrate 351 and light-emitting element 330, and part of the structure between substrate 352 and light-emitting element 330 are omitted. The display device 490A includes, for example, a transistor constituting a pixel circuit and an insulating layer 235 disposed to cover the transistor between substrate 351 and light-emitting element 330.

[0649] The display device 490A adopts an SBS (Side By Side) structure. In the SBS structure, the materials and structures of each light-emitting element can be optimized separately, increasing the freedom of material and structure selection, and making it easier to improve luminous intensity and reliability.

[0650] The display device 490A adopts a top-emitting type. In the top-emitting type, transistors and the like can be arranged in a way that overlaps with the light-emitting area of ​​the light-emitting element, so the pixel aperture ratio can be further improved compared with the bottom-emitting type.

[0651] Light-emitting elements 330R, 330G and 330B are disposed on the insulating layer 235.

[0652] The light-emitting element 330R includes a pixel electrode 311R on the insulating layer 235, an EL layer 313R on the pixel electrode 311R, and a common electrode 315 on the EL layer 313R. Figure 39A The light-emitting element 330R shown emits red (R) light. The EL layer 313R includes a light-emitting layer that emits red light.

[0653] The light-emitting element 330G includes a pixel electrode 311G on the insulating layer 235, an EL layer 313G on the pixel electrode 311G, and a common electrode 315 on the EL layer 313G. Figure 39A The light-emitting element 330G shown emits green (G) light. The EL layer 313G includes a light-emitting layer that emits green light.

[0654] The light-emitting element 330B includes a pixel electrode 311B on the insulating layer 235, an EL layer 313B on the pixel electrode 311B, and a common electrode 315 on the EL layer 313B. Figure 39A The light-emitting element 330B shown emits blue (B) light. The EL layer 313B includes a light-emitting layer that emits blue light.

[0655] Note that in Figure 39A The EL layers 313R, 313G, and 313B are shown with the same thickness, but this is not a limitation. The thicknesses of the EL layers 313R, 313G, and 313B can also be different. For example, it is preferable to set the thickness to enhance the optical path of the light emitted by the EL layers 313R, 313G, and 313B. This allows for the realization of a microcavity structure to improve the color purity of the light emitted from each light-emitting element.

[0656] Pixel electrode 311R is electrically connected to a transistor (not shown) included in the pixel circuit corresponding to light-emitting element 330R through openings provided in insulating layers 306, 395, and 235. Pixel electrode 311G is electrically connected to a transistor (not shown) included in the pixel circuit corresponding to light-emitting element 330G. Pixel electrode 311B is electrically connected to a transistor (not shown) included in the pixel circuit corresponding to light-emitting element 330B.

[0657] Each end of pixel electrode 311R, pixel electrode 311G, and pixel electrode 311B is covered by insulating layer 237. Insulating layer 237 serves as a partition wall. Insulating layer 237 can be configured as a single layer or a multilayer structure using one or both of inorganic and organic insulating materials. For example, insulating layer 237 can use materials suitable for insulating layer 395 and insulating layer 235. Insulating layer 237 electrically insulates the pixel electrodes from the common electrode. Furthermore, insulating layer 237 insulates adjacent light-emitting elements.

[0658] The common electrode 315 is a continuous film shared by light-emitting elements 330R, 330G, and 330B. In areas where no light-emitting elements are disposed, the common electrode 315 is electrically connected to a conductive layer formed using the same material and process as the pixel electrodes 311R, 311G, and 311B.

[0659] In one aspect of the display device of the present invention, the electrode serving as the light-extracting side of the pixel electrode and the common electrode preferably uses a conductive film that transmits visible light. Furthermore, the electrode serving as the non-light-extracting side preferably uses a conductive film that reflects visible light.

[0660] The electrode on the side that does not extract light can also be a conductive film that transmits visible light. In this case, it is preferable to place the electrode between the reflective layer and the EL layer. In other words, the light emitted from the EL layer can also be reflected by the reflective layer and extracted from the display device.

[0661] Metals, alloys, conductive compounds, and mixtures thereof can be appropriately used as materials for the pair of electrodes forming the light-emitting element. Specifically, examples of such materials include metals such as aluminum, magnesium, titanium, chromium, manganese, iron, cobalt, nickel, copper, gallium, zinc, indium, tin, molybdenum, tantalum, tungsten, palladium, gold, platinum, silver, yttrium, and neodymium, as well as alloys appropriately combined with them. Furthermore, examples of such materials include indium tin oxide (also known as In-Sn oxide or ITO), In-Si-Sn oxide (also known as ITSO), indium zinc oxide (In-Zn oxide), and In-W-Zn oxide. Additionally, examples of such materials include aluminum alloys (Al-Ni-La), silver and magnesium alloys, and silver alloys (Ag-Pd-Cu or APC), etc. In addition, as materials, examples include elements belonging to Group 1 or Group 2 of the periodic table (e.g., lithium, cesium, calcium, strontium), rare earth metals such as europium and ytterbium, alloys of these elements in appropriate combinations, and graphene.

[0662] The light-emitting element preferably employs a microcavity resonator (microcavity) structure. Therefore, one electrode of the light-emitting element is preferably an electrode with visible light transmittance and reflectance (semi-transmittance-semi-reflectance electrode), and the other electrode is preferably an electrode with visible light reflectance (reflection electrode). When the light-emitting element has a microcavity structure, the light emitted from the light-emitting layer can resonate between the two electrodes, and the light emitted from the light-emitting element can be enhanced.

[0663] The transparent electrode has a light transmittance of 40% or more. For example, it is preferable to use an electrode with a visible light (light with a wavelength of 400 nm or more and less than 750 nm) transmittance of 40% or more as the transparent electrode of the light-emitting element. The semi-transmissive-semi-reflective electrode has a visible light reflectance of 10% or more and less than 95%, preferably 30% or more and less than 80%. The reflective electrode has a visible light reflectance of 40% or more and less than 100%, preferably 70% or more and less than 100%. Furthermore, the resistivity of these electrodes is preferably 1 × 10⁻⁶. -2 Below Ωcm.

[0664] EL layers 313R, EL layers 313G, and EL layers 313B are all configured as islands. Figure 39A In this configuration, the ends of adjacent EL layers 313R overlap with the ends of EL layer 313G, and the ends of adjacent EL layers 313G overlap with the ends of EL layer 313B. Furthermore, although not shown, the ends of adjacent EL layers 313R overlap with the ends of EL layer 313B. When depositing island-shaped EL layers using a metal mask (or a high-precision metal mask), such as... Figure 39A As shown, sometimes the ends of adjacent EL layers overlap, but the present invention is not limited to this. That is, adjacent EL layers may also be separate without overlapping. Furthermore, in a display device, there may be both overlapping portions of adjacent EL layers and non-overlapping portions of adjacent EL layers.

[0665] EL layers 313R, EL layers 313G, and EL layers 313B all include at least a light-emitting layer. The light-emitting layer contains one or more light-emitting materials. Suitable light-emitting materials are those that emit light in colors such as blue, purple, blue-violet, green, yellow-green, yellow, orange, or red. Furthermore, materials that emit near-infrared light may also be used as light-emitting materials.

[0666] Examples of luminescent materials include fluorescent materials, phosphorescent materials, TADF materials, and quantum dot materials.

[0667] In addition to the luminescent material (guest material), the luminescent layer may also contain one or more organic compounds (host material, auxiliary material, etc.). As one or more organic compounds, one or both of the following can be used: a material with high hole transport (hole transport material) and a material with high electron transport (electron transport material). Furthermore, as one or more organic compounds, bipolar materials (materials with both high electron and hole transport properties) or TADF materials can also be used.

[0668] For example, the luminescent layer preferably comprises a combination of a phosphorescent material, a hole transport material that readily forms exciton complexes, and an electron transport material. By employing such a structure, ExTET (Exciplex-Triplet Energy Transfer), which utilizes energy transfer from the exciton complex to the luminescent material (phosphorescent material), can be efficiently obtained. By selecting a combination of exciton complexes that emit light with wavelengths overlapping the absorption band on the lowest energy side of the luminescent material, energy transfer can be facilitated, resulting in efficient luminescence. By employing the above structure, high efficiency, low-voltage operation, and long lifetime of the luminescent element can be simultaneously achieved.

[0669] In addition to the light-emitting layer, the EL layer may also include one or more of the following: a layer containing a material with high hole injection capability (hole injection layer), a layer containing a hole transport material (hole transport layer), a layer containing a material with high electron blocking capability (electron blocking layer), a layer containing a material with high electron injection capability (electron injection layer), a layer containing an electron transport material (electron transport layer), and a layer containing a material with high hole blocking capability (hole blocking layer). Furthermore, the EL layer may also include one or both of a bipolar material and a TADF material.

[0670] Light-emitting elements can use low-molecular-weight compounds or high-molecular-weight compounds, and may also contain inorganic compounds. The layers constituting the light-emitting element can be formed by methods such as vapor deposition (including vacuum vapor deposition), transfer printing, printing, inkjet printing, or coating.

[0671] Light-emitting elements can be single-structured (including structures with only one light-emitting unit) or series-structured (including structures with multiple light-emitting units). Each light-emitting unit includes at least one light-emitting layer. A series structure has multiple light-emitting units connected in series via a charge-generating layer. The charge-generating layer functions to inject electrons into one of the two light-emitting units and holes into the other when a voltage is applied between a pair of electrodes. By employing a series structure, light-emitting elements capable of emitting light with high intensity can be realized. Furthermore, the series structure improves reliability because it reduces the current required to achieve the same luminous intensity compared to a single structure. Additionally, the series structure can be referred to as a stacked structure.

[0672] exist Figure 39A When using a series-connected light-emitting element, it is preferred that the EL layer 313R includes a plurality of light-emitting units that emit red light, the EL layer 313G includes a plurality of light-emitting units that emit green light, and the EL layer 313B includes a plurality of light-emitting units that emit blue light.

[0673] A protective layer 331 is provided on light-emitting elements 330R, 330G, and 330B. The protective layer 331 and the substrate 352 are bonded together by an adhesive layer 342. A light-shielding layer 317 is provided on the substrate 352. For example, a solid sealing structure or a hollow sealing structure can be used to seal the light-emitting elements. Figure 39A In this configuration, the space between substrates 352 and 351 is filled with adhesive layer 342, thus employing a solid sealing structure. Alternatively, a hollow sealing structure can be used, where the space is filled with an inert gas (such as nitrogen or argon). In this case, adhesive layer 342 can also be arranged in a manner that does not overlap with the light-emitting element. Furthermore, a resin different from that used for the frame-shaped adhesive layer 342 can be used to fill the space.

[0674] By providing a protective layer 331 on the light-emitting elements 330R, 330G, and 330B, the reliability of the light-emitting elements can be improved.

[0675] The protective layer 331 can be a single-layer structure or a stacked structure of two or more layers. Furthermore, there are no limitations on the conductivity of the protective layer 331. At least one of insulating films, semiconductor films, and conductive films can be used as the protective layer 331.

[0676] When the protective layer 331 includes an inorganic film, it can suppress the deterioration of the light-emitting element, such as preventing the oxidation of the common electrode 315 and suppressing impurities (moisture, oxygen, etc.) from entering the light-emitting element, thereby improving the reliability of the display device.

[0677] Inorganic insulating films can be used as the protective layer 331. Examples of materials that can be used for inorganic insulating films include oxides, nitrides, oxynitrides, and oxynitrides. Specific examples of these inorganic insulating film materials are as described above. In particular, the protective layer 331 preferably comprises nitrides or oxynitrides, and more preferably comprises nitrides.

[0678] The protective layer 331 may also use an inorganic film comprising ITO, In-Zn oxide, Ga-Zn oxide, Al-Zn oxide, or IGZO. This inorganic film preferably has high resistance; specifically, it preferably has a higher resistance than the common electrode 315. The inorganic film may also contain nitrogen.

[0679] When the light emitted by the light-emitting element is extracted through the protective layer 331, the visible light transmittance of the protective layer 331 is preferably high. For example, ITO, IGZO, and alumina are all inorganic materials with high visible light transmittance, and are therefore preferred.

[0680] As a protective layer 331, for example, a stacked structure of an alumina film and a silicon nitride film on the alumina film, or a stacked structure of an alumina film and an IGZO film on the alumina film can be used. By using this stacked structure, impurities (such as water and oxygen) can be suppressed from entering the EL layer side.

[0681] Furthermore, the protective layer 331 may also include an organic film. For example, the protective layer 331 may include both an organic film and an inorganic film. Examples of organic films that can be used in the protective layer 331 include organic insulating films that can be used in the insulating layer 235.

[0682] The display device 490A is a top-emitting type. The light emitted by the light-emitting element is projected onto one side of the substrate 352. The substrate 352 is preferably made of a material with high visible light transmittance. The pixel electrodes 311R, 311G, and 311B contain materials that reflect visible light, and the counter electrode (common electrode 315) contains a material that allows visible light to pass through.

[0683] Preferably, a light-shielding layer 317 is provided on the surface of the substrate 352 on the substrate 351 side. The light-shielding layer 317 may be provided between adjacent light-emitting elements, etc.

[0684] Alternatively, a coloring layer such as a color filter can be provided on the surface of the substrate 352 on the substrate 351 side or on the protective layer 331. When a color filter is provided overlapping with the light-emitting element, the color purity of the light emitted from the pixel can be improved.

[0685] A coloring layer is a colored layer that selectively transmits light in a specific wavelength range while absorbing light in other wavelength ranges. For example, a red (R) filter that transmits light in the red wavelength range, a green (G) filter that transmits light in the green wavelength range, and a blue (B) filter that transmits light in the blue wavelength range can be used. Each coloring layer can be made of one or more of the following materials: metal, resin, pigment, and dye. The coloring layer is formed at the desired location using methods such as printing, inkjet printing, or etching using photolithography.

[0686] Furthermore, various optical components can be disposed on the outer side of the substrate 352 (the side opposite to the side of the substrate 351). Examples of optical components include polarizers, retardation plates, light diffusion layers (diffusion films, etc.), antireflective layers, and condensing films. Additionally, surface protective layers such as antistatic films to suppress dust adhesion, water-repellent films to prevent dirt accumulation, hard coatings to prevent damage during use, and impact absorption layers can also be disposed on the outer side of the substrate 352. For example, a glass layer or a silicon dioxide layer (SiO2) can be provided as a surface protective layer. x A protective layer (such as a diamond-like carbon layer) is preferred as it can prevent the surface from getting dirty or damaged. Additionally, DLC (diamond-like carbon) and aluminum oxide (Al₂O₃) can also be used as surface protective layers. x Materials such as polyester or polycarbonate can be used. Furthermore, materials with high transmittance of visible light are preferred as the surface protective layer. Additionally, materials with high hardness are preferred for the surface protective layer.

[0687] Substrates 351 and 352 can be made of glass, quartz, ceramic, sapphire, resin, metal, alloy, semiconductor, etc. The substrate on the side from which light is emitted from the light-emitting element uses a material that allows the light to pass through. By using a flexible material for substrates 351 and 352, the flexibility of the display device can be improved, thereby enabling flexible displays (e.g., bendable displays, foldable displays, rollable displays, sliding displays, and stretchable displays, etc.). A polarizer can also be used as at least one of substrates 351 and 352.

[0688] The substrates 351 and 352 can be made of materials such as: polyester resins such as polyethylene terephthalate (PET) or polyethylene naphthalate (PEN), polyacrylonitrile resin, acrylic resin, polyimide resin, polymethyl methacrylate resin, polycarbonate (PC) resin, polyethersulfone (PES) resin, polyamide resin (nylon, aromatic polyamide, etc.), polysiloxane resin, cycloolefin resin, polystyrene resin, polyamide-imide resin, polyurethane resin, polyvinyl chloride resin, polyvinylidene chloride resin, polypropylene resin, polytetrafluoroethylene (PTFE) resin, ABS resin, and cellulose nanofibers. Alternatively, at least one of the substrates 351 and 352 can be made of glass with a flexible thickness.

[0689] When a circular polarizer is superimposed on a display device, it is preferable to use a substrate with high optical isotropy as the substrate included in the display device. A substrate with high optical isotropy has lower birefringence (or, in other words, less birefringence). Examples of thin films with high optical isotropy include cellulose triacetate (TAC) films, cyclic olefin polymer (COP) films, cyclic olefin copolymer (COC) films, and acrylic resin films.

[0690] As the adhesive layer 342, various curing adhesives can be used, such as UV-curing adhesives, reactive 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. In particular, materials with low moisture permeability, such as epoxy resins, are preferred. Furthermore, two-component mixed resins can also be used. Additionally, adhesive sheets can also be used.

[0691] In one aspect of the present invention, when manufacturing a light-emitting element, vacuum processes such as vapor deposition and solution processes such as spin coating and inkjet printing can be utilized. Examples of vapor deposition methods include physical vapor deposition (PVD) methods such as sputtering, ion plating, ion beam vapor deposition, molecular beam vapor deposition, and vacuum vapor deposition, as well as chemical vapor deposition (CVD). In particular, functional layers (hole injection layer, hole transport layer, hole blocking layer, light-emitting layer, electron blocking layer, electron transport layer, electron injection layer, charge generation layer, etc.) included in the EL layer can be formed using methods such as vapor deposition (vacuum vapor deposition), coating methods (dip coating, dye coating, rod coating, spin coating, spray coating, etc.), and printing methods (inkjet printing, screen printing, offset printing, flexographic printing, photogravure printing, or microcontact printing, etc.).

[0692] [Structure Example 2]

[0693] Figure 39B The display device 490B shown includes light-emitting elements 330R, 330G, and 330B, a color layer 332R that transmits red light, a color layer 332G that transmits green light, and a color layer 332B that transmits blue light. The main difference between display device 490B and display device 490A is that in display device 490B, each color sub-pixel uses a light-emitting element including an EL layer 313 shared by the light-emitting elements, as well as a color layer (color filter, etc.). Note that sometimes the same parts as those in the above-described display device are omitted.

[0694] The light-emitting element 330R includes a pixel electrode 311R, an EL layer 313 on the pixel electrode 311R, and a common electrode 315 on the EL layer 313. The light emitted by the light-emitting element 330R is extracted as red light through the color layer 332R and sent to the outside of the display device 490B.

[0695] The light-emitting element 330G includes a pixel electrode 311G, an EL layer 313 on the pixel electrode 311G, and a common electrode 315 on the EL layer 313. The light emitted by the light-emitting element 330G is extracted as green light through the coloring layer 332G and sent to the outside of the display device 490B.

[0696] The light-emitting element 330B includes a pixel electrode 311B, an EL layer 313 on the pixel electrode 311B, and a common electrode 315 on the EL layer 313. The light emitted by the light-emitting element 330B is extracted as blue light through the color layer 332B and sent to the outside of the display device 490B.

[0697] Light-emitting elements 330R, 330G, and 330B share an EL layer 313 and a common electrode 315. Compared to a structure where each color sub-pixel has a different EL layer, the structure where each color sub-pixel shares an EL layer 313 can reduce the number of manufacturing steps.

[0698] For example, Figure 39B The light-emitting elements 330R, 330G, and 330B shown emit white light. The white light emitted by the light-emitting elements 330R, 330G, and 330B is transmitted through the coloring layers 332R, 332G, and 332B, thereby obtaining light of the desired color.

[0699] White light-emitting elements preferably include two or more light-emitting layers. When white light emission is achieved using two light-emitting layers, the light-emitting layers are selected such that the emission colors of the two light-emitting layers are complementary. For example, by making the emission colors of the first light-emitting layer and the second light-emitting layer complementary, a structure in which the entire light-emitting element emits white light can be obtained. Furthermore, when white light emission is achieved using three or more light-emitting layers, the emission colors of the three or more light-emitting layers are combined to obtain a structure in which the entire light-emitting element emits white light.

[0700] The EL layer 313 preferably includes, for example, a light-emitting layer containing a light-emitting material that emits blue light and a light-emitting layer containing a light-emitting material that emits visible light with a wavelength longer than blue. The EL layer 313 preferably includes, for example, a light-emitting layer that emits yellow light and a light-emitting layer that emits blue light. Alternatively, the EL layer 313 preferably includes, for example, a light-emitting layer that emits red light, a light-emitting layer that emits green light, and a light-emitting layer that emits blue light.

[0701] The light-emitting element emitting white light is preferably arranged in a series structure. Specifically, it can adopt: a two-stage series structure including a light-emitting unit emitting yellow (Y) light and a light-emitting unit emitting blue (B) light; a two-stage series structure including a light-emitting unit emitting red (R) light and green (G) light and a light-emitting unit emitting blue light; a three-stage series structure including a light-emitting unit emitting blue light, a light-emitting unit emitting yellow light, yellow-green light or green light and a light-emitting unit emitting blue light; or a three-stage series structure including a light-emitting unit emitting blue light, a light-emitting unit emitting yellow light, yellow-green light or green light and a light-emitting unit emitting red light and a light-emitting unit emitting blue light, etc. For example, regarding the number of layers and color order of the light-emitting units, examples include a two-level structure with B and Y stacked from the anode side, a two-level structure with B and X (light-emitting unit X) stacked, a three-level structure with B, Y, and B stacked, and a three-level structure with B, X, and B stacked. Regarding the number of layers and color order of the light-emitting layers in light-emitting unit X, examples include a two-layer structure with R and Y stacked from the anode side, a two-layer structure with R and G stacked, a two-layer structure with G and R stacked, a three-layer structure with G, R, and G stacked, or a three-layer structure with R, G, and R stacked. Furthermore, other layers can be placed between the two light-emitting layers.

[0702] In addition, by employing a microcavity structure, light-emitting elements that emit white light can sometimes enhance specific colors such as red, green, or blue to emit light.

[0703] Or, for example Figure 39BThe light-emitting ...

Claims

1. A semiconductor device, comprising: First transistor; Second transistor; as well as The third transistor, The first transistor includes a first gate, a second gate opposite to the first gate via a channel forming region of the first transistor, a first source, and a first drain. The second transistor includes a third gate, a second source, and a second drain. The third transistor includes a fourth gate, a third source, and a third drain. One of the first source and the first drain is electrically connected to one of the second source and the second drain. The other of the first source and the first drain is electrically connected to one of the third source and the third drain. The first gate is electrically connected to the third gate. Furthermore, the second gate is electrically connected to the other of the first source and the first drain.

2. The semiconductor device according to claim 1, The second transistor includes a fifth gate opposite to the third gate, which is located across the channel forming region of the second transistor. Furthermore, the fifth gate is electrically connected to the third gate.

3. The semiconductor device according to claim 1 or 2, The other of the second source and the second drain is supplied with a first potential. The third source and the third drain are supplied with a second potential higher than the first potential. The first gate and the third gate are supplied with a first pulse signal. Furthermore, the fourth gate is supplied with a second pulse signal with a timing different from that of the first pulse signal.

4. The semiconductor device according to claim 1 or 2, The thickness of the gate insulating film of the second gate is greater than the thickness of the gate insulating film of the first gate.

5. The semiconductor device according to claim 1 or 2, The channel lengths of the first transistor and the second transistor are smaller than the channel length of the third transistor.

6. The semiconductor device according to claim 1 or 2, The channel region of the first transistor comprises an oxide semiconductor.

7. A semiconductor device, comprising: First transistor; Second transistor; as well as The third transistor, The first transistor includes a first gate, a second gate opposite to the first gate via a channel forming region of the first transistor, a first source, and a first drain. The second transistor includes a third gate, a second source, and a second drain. The third transistor includes a fourth gate, a third source, and a third drain. One of the first source and the first drain is electrically connected to one of the second source and the second drain. The other of the second source and the second drain is electrically connected to one of the third source and the third drain. The first gate is electrically connected to the third gate. Furthermore, the second gate is electrically connected to the other of the first source and the first drain.

8. The semiconductor device according to claim 7, The second transistor includes a fifth gate opposite to the third gate, which is located across the channel forming region of the second transistor. Furthermore, the fifth gate is electrically connected to the third gate.

9. The semiconductor device according to claim 7 or 8, The third source and the third drain are supplied with a first potential. The other of the first source and the first drain is supplied with a second potential higher than the first potential. The first gate and the third gate are supplied with a first pulse signal. Furthermore, the fourth gate is supplied with a second pulse signal with a timing different from that of the first pulse signal.

10. The semiconductor device according to claim 7 or 8, The thickness of the gate insulating film of the second gate is greater than the thickness of the gate insulating film of the first gate.

11. The semiconductor device according to claim 7 or 8, The channel lengths of the first transistor and the second transistor are smaller than the channel length of the third transistor.

12. The semiconductor device according to claim 7 or 8, The channel region of the first transistor comprises an oxide semiconductor.

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