Semiconductor device

Abstract

A novel semiconductor device is provided. The semiconductor device includes: a first conductive layer serving as a drain of a first transistor; a second conductive layer on the first conductive layer and serving as a source of the first transistor; a first semiconductor layer including a channel formation region of the first transistor; a third conductive layer having a shape along a side surface of the first semiconductor layer and including a region serving as a gate of the first transistor, a region serving as a drain of a second transistor over the first transistor, and a region in contact with the second conductive layer; a fourth conductive layer on the third conductive layer and serving as a source of the second transistor; a second semiconductor layer including a channel formation region of the second transistor; and a fifth conductive layer having a shape along a side surface of the second semiconductor layer and including a region serving as a gate of the second transistor and a region in contact with the fourth conductive layer, the first and fifth conductive layers having functions of power supply lines, and the third conductive layer having functions of signal lines.

Description

TECHNICAL FIELD

[0001] One embodiment of the present application relates to a semiconductor device.

[0002] Note that one embodiment of the present application is not limited to the technical field described above. The technical field of one embodiment of the present application disclosed in this specification and the like relates to an object, a method, a driving method or a manufacturing method. Furthermore, one embodiment of the present application relates to a process, a machine, a manufacture, or a composition of matter. Specifically, as one example of the technical field of one embodiment of the present application disclosed in this specification and the like, a semiconductor device, a display device, a light-emitting device, a power storage device, an optical device, an imaging device, a lighting device, an operation device, a control device, a memory device, an input device, an output device, an input and output device, a signal processing device, an arithmetic processing device, an electronic computer, an electronic appliance, a driving method thereof, or a manufacturing method thereof can be given. BACKGROUND

[0003] It is known that a transistor including an oxide semiconductor in a channel formation region has extremely small off-state current. For example, Patent Document 1 discloses a low-power-consumption operation processing device (e.g., CPU or the like) to which the transistor is applied, which has small off-state current. Furthermore, for example, Patent Document 2 discloses a memory device (e.g., main memory, cache memory, or the like) which can store data for a long time by utilizing the transistor, which has small off-state current.

[0004] Furthermore, for example, Patent Document 3 discloses a technique for achieving high integration of an integrated circuit by stacking the transistor.

[0005] [Prior Art Documents]

[0006] [Patent Documents]

[0007] [Patent Document 1] Japanese Published Patent Application No. 2012-257187

[0008] [Patent Document 2] Japanese Published Patent Application No. 2011-151383

[0009] [Patent Document 3] International Publication No. 2021 / 053473 SUMMARY

[0010] PROBLEMS TO BE SOLVED BY THE INVENTION

[0011] One of objects of one embodiment of the present application is to provide a semiconductor device or a memory device including the semiconductor device, or the like, which has high reliability. Another object of one embodiment of the present application is to provide a semiconductor device or a memory device including the semiconductor device, or the like, which is small. Another object of one embodiment of the present application is to provide a semiconductor device or a memory device including the semiconductor device, or the like, which can operate at high speed. Another object of one embodiment of the present application is to provide a semiconductor device or a memory device including the semiconductor device, or the like, which can reduce power consumption. Another object of one embodiment of the present application is to provide a novel semiconductor device or a memory device including the semiconductor device, or the like.

[0012] Note that the above-described objects are not necessarily exclusive of each other. Note that one embodiment of the present application does not necessarily achieve all the above-described objects. Other objects can be extracted from the description of the specification, the attached drawings, or the like, and can be apparent to those skilled in the art from the description.

[0013] Means for solving the technical problem (1)

[0015] One embodiment of the present application is a semiconductor device including a first conductive layer including a region serving as one of a source and a drain of a first transistor and extending in a first direction, a second conductive layer positioned on the first conductive layer and including a region serving as the other of the source and the drain of the first transistor, a first semiconductor layer including a channel formation region of the first transistor, a third conductive layer having a shape along a side surface of the first semiconductor layer, including a region serving as a gate of the first transistor, a region serving as one of a source and a drain of a second transistor over the first transistor, and a region in contact with the second conductive layer and extending in a second direction intersecting the first direction, a fourth conductive layer positioned on the third conductive layer and including a region serving as the other of the source and the drain of the second transistor, a second semiconductor layer including a channel formation region of the second transistor, and a fifth conductive layer having a shape along a side surface of the second semiconductor layer, including a region serving as a gate of the second transistor and a region in contact with the fourth conductive layer and extending in the first direction, wherein one of the first conductive layer and the fifth conductive layer has a function of a first power supply line, the other of the first conductive layer and the fifth conductive layer has a function of a second power supply line to which a higher potential than a potential supplied to the first power supply line is supplied, and the third conductive layer has a function of a signal line to which a signal of a potential higher than or equal to a potential of the first power supply line and lower than a potential of the second power supply line is supplied. (2)

[0017] In the above (1), the channel length of the first transistor can be smaller than the channel width of the first transistor, and the channel length of the second transistor can be smaller than the channel width of the second transistor. (3)

[0019] In the above (1), the first semiconductor layer and the second semiconductor layer can each include an oxide semiconductor. (4)

[0021] In the above (1), the first conductive layer can function as a second power supply line, and the fifth conductive layer can function as a first power supply line.

[0022] Effects of Invention

[0023] According to one embodiment of the present application, a semiconductor device with high reliability, a memory device including the semiconductor device, or the like can be provided. According to one embodiment of the present application, a semiconductor device with small size, a memory device including the semiconductor device, or the like can be provided. According to one embodiment of the present application, a semiconductor device capable of improving operation speed, a memory device including the semiconductor device, or the like can be provided. According to one embodiment of the present application, a semiconductor device capable of reducing power consumption, a memory device including the semiconductor device, or the like can be provided. According to one embodiment of the present application, a novel semiconductor device, a memory device including the semiconductor device, or the like can be provided.

[0024] Note that the above effects do not preclude the existence of other effects. One embodiment of the present application does not necessarily achieve all the above effects. Other effects that are apparent from the description, the drawings, or the like can be derived as necessary in addition to the above effects. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1A FIG. 1 is a top view illustrating a structure example of a semiconductor device. Figure 1B FIG. 2 is a cross-sectional view illustrating a structure example of the semiconductor device. Figure 1C FIG. 3 is a circuit diagram illustrating a structure example of the semiconductor device. Figure 1D FIG. 4 is a circuit diagram illustrating a structure example of the semiconductor device.

[0026] Figure 2A FIG. 5 is a cross-sectional view illustrating a structure example of the semiconductor device. Figure 2B

[0027] Figure 3A FIG. 6 is a top view illustrating a structure example of a semiconductor device. Figure 3B FIG. 7 is a cross-sectional view illustrating a structure example of the semiconductor device.

[0028] Figure 4A FIG. 8 is a top view illustrating a structure example of a semiconductor device. Figure 4B ​is a cross-sectional view showing a structure example of a semiconductor device.

[0029] Figure 5A is a plan view showing a structure example of a semiconductor device. Figure 5B and Figure 5C is a cross-sectional view showing a structure example of a semiconductor device.

[0030] Figures 6A to 6C is a circuit diagram showing a structure example of a semiconductor device.

[0031] Figure 7 is a cross-sectional view showing a structure example of a semiconductor device.

[0032] Figure 8 is a cross-sectional view showing a structure example of a semiconductor device.

[0033] Figures 9A to 9C is a cross-sectional view showing a structure example of a semiconductor device.

[0034] Figures 10A to 10D is a circuit diagram showing a structure example of a semiconductor device.

[0035] Figure 11A is a plan view showing a structure example of a semiconductor device. Figure 11B is a cross-sectional view showing a structure example of a semiconductor device.

[0036] Figure 12 is a cross-sectional view showing a structure example of a semiconductor device.

[0037] Figure 13A is a plan view showing a structure example of a semiconductor device. Figure 13B and Figure 13C is a cross-sectional view showing a structure example of a semiconductor device.

[0038] Figure 14A is a plan view showing a structure example of a semiconductor device. Figure 14B is a perspective view showing a structure example of a semiconductor device. Figures 14C to 14E is a cross-sectional view showing a structure example of a semiconductor device.

[0039] Figure 15A and Figure 15B is a cross-sectional view showing a structure example of a semiconductor device.

[0040] Figure 16A is a plan view showing a structure example of a semiconductor device. Figure 16B is a perspective view showing a structure example of a semiconductor device. Figures 16C to 16E is a cross-sectional view showing a structure example of a semiconductor device.

[0041] Figure 17 is a cross-sectional view showing a structure example of a semiconductor device.

[0042] Figure 18A is a plan view showing a structure example of a semiconductor device. Figure 18B is a perspective view showing a structure example of a semiconductor device. Figures 18C to 18E is a cross-sectional view showing a structure example of a semiconductor device.

[0043] Figure 19 is a cross-sectional view showing a structure example of a semiconductor device.

[0044] Figure 20 is a cross-sectional view showing a structure example of a semiconductor device.

[0045] Figure 21 is a diagram showing a structure example of a storage device.

[0046] Figures 22A to 22H is a diagram showing a circuit structure example of a storage unit.

[0047] Figure 23 is a diagram showing various storage devices in a hierarchy.

[0048] Figure 24A and Figure 24B is a diagram showing one example of an electronic component.

[0049] Figure 25A and Figure 25B is a diagram showing one example of an electronic device. Figures 25C to 25E is a diagram showing one example of a large computer.

[0050] Figure 26A is a diagram showing one example of a space device. Figure 26B is a diagram showing one example of a storage system that can be used in a data center.

[0051] Figures 27A1 to 27A7 and Figures 27B1 to 27B6 is a diagram showing "connection". DETAILED DESCRIPTION

[0052] 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.

[0053] 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. Therefore, the present invention should not be construed as being limited to the contents described in the embodiments.

[0054] 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.

[0055] Note that, regarding the accompanying drawings illustrating the embodiments, in the structure of the invention, the same symbols are sometimes used in different drawings to represent the same parts or parts having the same function, thereby omitting repeated descriptions. Furthermore, in the drawings, when parts having the same function are represented, the same shading lines are sometimes used, for example, without specifically adding additional symbols. For example, in perspective views or top views (also called "plan views"), for clarity, illustrations of some constituent elements are sometimes omitted. For example, descriptions of some hidden lines in the drawings are sometimes omitted. Furthermore, for example, descriptions of shading lines, etc., in the drawings are sometimes omitted.

[0056] In the drawings, the size, the thickness, or the region is sometimes exaggerated for clarity in some cases. Therefore, the drawings are not necessarily limited to the size or the aspect ratio in the drawings. Furthermore, in the drawings, an ideal example is schematically shown, and thus the present application is not necessarily limited to the shape or the value shown in the drawings, for example. For example, in an actual manufacturing process, a layer or a resist mask and the like are sometimes unintentionally thinned due to processing such as etching, but are not always reflected in the drawings for convenience of understanding. Furthermore, for example, in an actual circuit operation, unevenness of voltage or current and the like is sometimes caused due to noise or timing skew, but they are not always reflected in the drawings for convenience of understanding.

[0057] In the present specification and the drawings and the like, components are classified according to functions and are shown as independent components. However, it is difficult to classify components according to functions, and one component can be involved in a plurality of functions or a plurality of components can be involved in one function. Therefore, the components shown in the present specification and the drawings and the like are not limited to the description thereof, and can be appropriately changed.

[0058] In the present specification and the drawings and the like, when a plurality of components are denoted by the same reference numeral and it is necessary to distinguish them, a symbol is sometimes added, such as "a", "b", "_1", "[n]", or "[m, n]" and the like. Furthermore, when contents common to a plurality of components to which the added symbol is added are explained or it is not necessary to distinguish them, the added symbol is sometimes not added and is described.

[0059] Note that in the present specification and the like, the "on state" or the "open state" of a transistor refers to a state in which the source and the drain of the transistor can be regarded as being electrically short-circuited, or a state in which current can flow between the source and the drain (also referred to as a state in which current can flow), for example. For example, the "on state" or the "open state" is referred to as a state in which the voltage between the gate and the source of an n-channel transistor is higher than the threshold voltage, or a state in which the voltage between the gate and the source of a p-channel transistor is lower than the threshold voltage, for example. In addition, the "off state", the "closed state", or the "blocking state" of a transistor refers to a state in which the source and the drain of the transistor can be regarded as being electrically disconnected. For example, the "off state", the "closed state", or the "blocking state" is referred to as a state in which the voltage between the gate and the source of an n-channel transistor is lower than the threshold voltage, or a state in which the voltage between the gate and the source of a p-channel transistor is higher than the threshold voltage, for example.

[0060] Further, in this specification and the like, a voltage between the gate and the source (gate-source voltage) is also referred to as a "gate voltage", a voltage between the drain and the source (drain-source voltage) is also referred to as a "drain voltage", and a voltage between the back gate and the source (back gate-source voltage) is also referred to as a "back gate voltage". Further, a current flowing between the drain and the source is also referred to as a "drain current". Note that the description "high gate voltage", "high drain voltage", and "high back gate voltage" of an n-channel transistor can be switched to the description "low gate voltage", "low drain voltage", and "low back gate voltage" of a p-channel transistor as appropriate. Further, the description "low gate voltage", "low drain voltage", and "low back gate voltage" of an n-channel transistor can be switched to the description "high gate voltage", "high drain voltage", and "high back gate voltage" of a p-channel transistor as appropriate.

[0061] Further, in this specification and the like, unless particularly stated otherwise, an "off-state current" of a transistor refers to a drain current when the transistor is in an off state. Note that in this specification and the like, an off-state current and a current flowing between a gate and a source and a drain (also referred to as a gate drain current) are also referred to as a leakage current.

[0062] (Embodiment 1)

[0063] A semiconductor device according to one embodiment of the present application is described with reference to drawings. For example, at least a part of a semiconductor device according to one embodiment of the present application can be used for an electrostatic discharge (ESD: Electro-Static Discharge) protection circuit.

[0064] <Structure Example 1 of Semiconductor Device>

[0065] Figures 1A to 1C is a top view and cross-sectional views illustrating a structure example of a semiconductor device according to one embodiment of the present application. Figure 1D is a circuit diagram illustrating the semiconductor device.

[0066] Figure 1A is a top view of a semiconductor device 100. Figure 1B is a cross-sectional view of a portion indicated by a dot-and-dash line A1-A2 in Figure 1A . Further, in Figure 1C , a portion indicated by a dot-and-dash line A3-A4 in Figure 1A is a cross-sectional view. Note that in the top view of Figure 1A , part of the components is omitted for clarity.

[0067] Figure 1B and Figure 1CThe diagram shows an insulator 620, a transistor 600a on the insulator 620, a transistor 600b on the transistor 600a, an insulator 640a on the insulator 620, an insulator 640b on the insulator 640a, and an insulator 678 on the transistors 600a and 600b. Insulators 620, 640a, 640b, and 678 all function as interlayer films and protective films.

[0068] Additionally, a conductor 630 functioning as one of the source and drain electrodes of transistor 600a, a conductor 660a functioning as the other of the source and drain electrodes, an oxide 650a functioning as a semiconductor film including a channel forming region, and an insulator 672a functioning as a gate insulating film are also shown. Furthermore, a conductor 670a functioning as the gate electrode of transistor 600a and as one of the source and drain electrodes of transistor 600b are also shown. Additionally, a conductor 660b functioning as the other of the source and drain electrodes of transistor 600b, an oxide 650b functioning as a semiconductor film including a channel forming region, an insulator 672b functioning as a gate insulating film, and a conductor 670b functioning as a gate electrode are also shown. Furthermore, conductors 630, 660a, 670a, 660b, and 670b all also have wiring functions.

[0069] In addition, to facilitate the explanation of the positional relationship of the constituent elements, the X, Y, and Z directions are sometimes specified in this specification and accompanying drawings. The X, Y, and Z directions are perpendicular to each other. The X and Y directions are along the surfaces on which transistors 600a and 600b are formed (e.g., the top surface of insulator 620). The Z direction is the direction in which transistors 600a and 600b are stacked. Furthermore, in this specification, the Z direction is sometimes referred to as the longitudinal direction or the height direction.

[0070] Therefore, in this specification, etc., "conductor" may be appropriately replaced with "conductive layer" or "conductive film". Similarly, "insulator" may be appropriately replaced with "insulating layer" or "insulating film".

[0071] like Figure 1B As shown, conductor 630 extends in the X direction. Figure 1C As shown, conductor 670a extends in the Y direction and contacts conductor 660a through opening 676a provided in insulator 672a. Figure 1B As shown, conductor 670b extends in the X direction and contacts conductor 660b through opening 676b provided in insulator 672b.

[0072] In other words, each of the transistor 600a and the transistor 600b is a diode-connected transistor. Note that in this specification and the like, a transistor in which a gate is connected to either one of a source and a drain is referred to as a diode-connected transistor.

[0073] As Figure 1B and Figure 1C is illustrated, an opening 648a reaching the conductive body 630 is provided in the insulator 640a and the conductive body 660a, and at least part of a structure of the transistor 600a is arranged in the opening 648a. Further, an opening 648b reaching the conductive body 670a is provided in the insulator 640b and the conductive body 660b, and at least part of a structure of the transistor 600b is arranged in the opening 648b.

[0074] Specifically, in the transistor 600a, part of the oxide 650a includes a region along a side surface of the opening 648a, a region in contact with a top surface of the conductive body 630, and a region in contact with a side surface of the conductive body 660a, and the region of the oxide 650a along the side surface of the opening 648a includes a channel formation region. Part of the insulator 672a is provided along a side surface of the oxide 650a. Part of the conductive body 670a is provided along a side surface of the insulator 672a. In other words, part of the conductive body 670a has a shape along the side surface of the oxide 650a inside the opening 648a. Further, in the transistor 600b, part of the oxide 650b includes a region along a side surface of the opening 648b, a region in contact with a top surface of the conductive body 670a, and a region in contact with a side surface of the conductive body 660b, and the region of the oxide 650b along the side surface of the opening 648b includes a channel formation region. Part of the insulator 672b is provided along a side surface of the oxide 650b. Part of the conductive body 670b is provided along a side surface of the insulator 672b. In other words, part of the conductive body 670b has a shape along the side surface of the oxide 650b inside the opening 648b.

[0075] Note that in this specification and the like, in an insulator, a conductive body, or the like in which an opening is provided, a side surface of the insulator, the conductive body, or the like in the opening is sometimes referred to as a side surface of the opening. Thus, for example, the "side surface of the opening 648a" can be appropriately referred to as the "side surface of the insulator 640a and the conductive body 660a in the opening 648a" or the like. Further, for example, the "side surface of the opening 648b" can be appropriately referred to as the "side surface of the insulator 640b and the conductive body 660b in the opening 648b" or the like.

[0076] Thus, in the semiconductor device 100, each of the transistor 600a and the transistor 600b can be reduced in the area occupied in plan view.

[0077] Here, it can be said that the channel length directions of transistors 600a and 600b have a longitudinal ( Figures 1A to 1C The component in the Z direction (i.e., the depth direction when viewed from above), the height direction, or the direction perpendicular to the surface being formed. In other words, it can also be said that the length direction of each channel of transistor 600a and transistor 600b has a component of its stacking direction. That is to say, the source electrode and the drain electrode are located at different heights and the drain current flows in the longitudinal direction. In this specification, transistors with a longitudinal component in the channel length direction (i.e., transistors with drain current flowing in the longitudinal direction) are sometimes referred to as VFET (Vertical Field Effect Transistor), vertical transistor, vertical channel transistor, etc.

[0078] In addition, such as Figures 1A to 1C As shown, transistors 600a and 600b are arranged in a manner that shares a common structure and overlaps each other when viewed from above. Alternatively, the channel forming regions of transistor 600a in oxide 650a and transistor 600b in oxide 650b can also be arranged in a manner that overlaps each other when viewed from above. This reduces the area occupied by the semiconductor device 100.

[0079] That is to say, in Figures 1A to 1C In the semiconductor device 100 shown, conductors 670b and 660b are located above conductor 670a, and conductors 670a and 660a are located above conductor 630. Furthermore, conductor 670b includes a region used for wiring and a region used as the gate electrode of transistor 600b. Conductor 670a includes a region used for wiring, a region used as one of the source and drain electrodes of transistor 600b, and a region used as the gate electrode of transistor 600a. Conductor 660b includes a region used as the other of the source and drain electrodes of transistor 600b and a region used for wiring. Conductor 630 includes a region used as one of the source and drain electrodes of transistor 600a and a region used for wiring. Conductor 660a includes a region used as the other of the source and drain electrodes of transistor 600a and a region used for wiring. At this time, conductors 670b, 660b, 670a, 660a, and 630 include overlapping regions when viewed from above. In addition, when viewed from above, the length direction of each channel of transistor 600b and transistor 600a is the depth direction (i.e., the Z direction).

[0080] Each of the conductors included in the semiconductor device 100 can have a single-layer structure or a stacked-layer structure of two or more layers. For example, the conductor 630 can have a structure in which a conductor having a function of a wiring and a conductor having a function of one of a source electrode and a drain electrode of the transistor 600a are stacked. Further, for example, the conductor 660a can have a structure in which a conductor having a function of a wiring and a conductor having a function of the other of the source electrode and the drain electrode of the transistor 600a are stacked. Further, for example, the conductor 670a can have a structure in which a conductor having a function of a gate electrode of the transistor 600a, a conductor having a function of a wiring, and a conductor having a function of one of a source electrode and a drain electrode of the transistor 600b are stacked. Further, for example, the conductor 660b can have a structure in which a conductor having a function of a wiring and a conductor having a function of the other of the source electrode and the drain electrode of the transistor 600b are stacked. Further, for example, the conductor 670b can have a structure in which a conductor having a function of a gate electrode of the transistor 600b and a conductor having a function of a wiring are stacked.

[0081] Here, Figure 1D The circuit diagram illustrated in FIG. 6A shows a transistor M11 which corresponds to the transistor 600a and a transistor M12 which corresponds to the transistor 600b. One of a source and a drain of the transistor M11 is connected to a wiring VLD. The other of the source and the drain of the transistor M11 is connected to a gate of the transistor M11, one of a source and a drain of the transistor M12, and a wiring SIG. The other of the source and the drain of the transistor M12 is connected to a gate of the transistor M12 and a wiring VLS.

[0082] The wiring VLD corresponds to the conductor 630. The wiring SIG corresponds to the conductor 660a and the conductor 670a. The wiring VLS corresponds to the conductor 660b and the conductor 670b. Note that in Figures 1A to 1C the conductors each corresponding to the wiring VLD, the wiring SIG, and the wiring VLS are given symbols in parentheses.

[0083] In one embodiment of the present application, the semiconductor device 100 can be used as an ESD protection circuit. That is, the semiconductor device 100 has a function of an ESD protection circuit.

[0084] In the case where the semiconductor device 100 is used as an ESD protection circuit, the wiring SIG has a function of a signal line, and the wiring VLD and the wiring VLS each have a function of a power supply line. In addition, the transistor 600a and the transistor 600b each connected to a diode have a function of an ESD protection diode.

[0085] Here, for example, the wiring SIG is supplied with a digital signal or an analog signal of a potential VSS or less and a potential VDD or more. At this time, in the case where both the transistor 600a and the transistor 600b are n-channel transistors, by supplying the wiring VLD with the potential VDD and the wiring VLS with the potential VSS, the semiconductor device 100 can be used as an ESD protection circuit. Alternatively, in the case where both the transistor 600a and the transistor 600b are p-channel transistors, by supplying the wiring VLD with the potential VSS and the wiring VLS with the potential VDD, the semiconductor device 100 can be used as an ESD protection circuit.

[0086] For example, in the case where the wiring SIG is connected to another circuit (not shown), by releasing a surge generated in the wiring SIG due to ESD or the like to at least one of the wiring VLD and the wiring VLS, the circuit can be protected from the surge. For example, a gate insulating film of a transistor included in the circuit can be prevented from being damaged. Thus, the reliability of the circuit can be improved.

[0087] At this time, in the transistor 600a and the transistor 600b, the channel length can also be made smaller than the channel width. By this means, the on-state current of each of the transistor 600a and the transistor 600b which has a function of an ESD protection diode can be increased. Thus, a surge generated in the wiring SIG due to ESD or the like can be easily released to the wiring VLD and the wiring VLS, and thus the reliability can be improved.

[0088] Further, in a vertical transistor like the transistor 600a and the transistor 600b, the channel length can be set to be smaller than the exposure limit of photolithography, and thus the on-state current can be easily increased, and details thereof will be described later.

[0089] The semiconductor device 100 of one embodiment of the present application has a structure in which, in plan view, the transistor 600a and the transistor 600b are provided in a region where the conductive body 670b corresponding to the wiring VLS, the conductive body 670a corresponding to the wiring SIG, and the conductive body 630 corresponding to the wiring VLD overlap. That is, the transistor 600a and the transistor 600b which have a function of an ESD protection diode can be arranged so as to overlap the wiring SIG which has a function of a signal line. Thus, in plan view, the transistor 600a, the transistor 600b, and each of the conductive bodies which have a function of a wiring can be provided without a large increase in area occupancy. In other words, the ESD protection circuit can be provided without a large increase in area occupancy.

[0090] Here, as described above, the semiconductor device 100 can be used as an ESD protection circuit. Figure 1AAs shown, the conductive body 630 corresponding to the wiring VLS and the conductive body 670b corresponding to the wiring VLD each can cross the conductive body 670a corresponding to the wiring SIG when viewed in plan. That is, the direction in which the conductive body 630 and the conductive body 670b each extend can cross the direction in which the conductive body 670a extends. Thereby, the region in which the conductive body 630 and the conductive body 670a overlap each other can be reduced to reduce the parasitic capacitance of the conductive body 670a. Further, the region in which the conductive body 670b and the conductive body 670a overlap each other can be reduced to reduce the parasitic capacitance of the conductive body 670a. By reducing the parasitic capacitance of the conductive body 670a corresponding to the wiring SIG, the delay time of a signal transmitted through the wiring SIG can be shortened.

[0091] For example, in the case where the wiring SIG is connected to another circuit (not shown), the reduction in the operation speed of the circuit due to the provision of the semiconductor device 100 having the function of the ESD protection circuit can be suppressed.

[0092] Further, in the semiconductor device 100 shown, Figures 1A to 1C In the semiconductor device 100 shown, either the conductive body 660a can be used instead of the conductive body 670a extending in the Y direction, or both the conductive body 670a and the conductive body 660a can be used to extend in the Y direction. In particular, by using both the conductive body 670a and the conductive body 660a to extend in the Y direction, the parasitic resistance of the wiring SIG corresponding to the conductive body 670a and the conductive body 660a can be reduced. By reducing the parasitic resistance of the wiring SIG, the delay time of a signal transmitted through the wiring SIG can be shortened.

[0093] For example, in the case where the wiring SIG is connected to another circuit (not shown), the reduction in the operation speed of the circuit due to the provision of the semiconductor device 100 having the function of the ESD protection circuit can be suppressed.

[0094] Further, in the semiconductor device 100 shown, Figures 1A to 1C In the semiconductor device 100 shown, either the conductive body 660b can be used instead of the conductive body 670b extending in the X direction, or both the conductive body 670b and the conductive body 660b can be used to extend in the X direction. In particular, by using both the conductive body 670b and the conductive body 660b to extend in the X direction, the parasitic resistance of the wiring VLS corresponding to the conductive body 670b and the conductive body 660b can be reduced. By reducing the parasitic resistance of the wiring VLS, the potential supplied through the wiring VLS can be stabilized.

[0095] For example, in the case where the wiring VLS is connected to another circuit (not shown), the potential supplied to the circuit through the wiring VLS can be stabilized, and thus the stabilization of the circuit can be achieved.

[0096] In the semiconductor device 100, for example, each of the oxide 650a and the oxide 650b can be formed using a single crystal semiconductor, a polycrystal semiconductor, a microcrystal semiconductor, or an amorphous semiconductor. In addition, as the semiconductor, a compound semiconductor (e.g., silicon germanium or gallium arsenide) or an oxide semiconductor, in addition to a single semiconductor (e.g., silicon or germanium) whose main component is a single element, can be used.

[0097] Note that the oxide 650a and the oxide 650b can include the same material or different materials.

[0098] In the semiconductor device 100 of one embodiment of the present application, each of the oxide 650a and the oxide 650b can include an oxide semiconductor. In this specification and the like, a transistor including an oxide semiconductor in a channel formation region is referred to as an OS transistor. Thus, in the semiconductor device 100 of one embodiment of the present application, an OS transistor can be used as at least one of the transistor 600a and the transistor 600b.

[0099] Hereinafter, in the case where the transistor 600a and the transistor 600b each include an OS transistor, which is not particularly stated, is described as an example.

[0100] Note that the structure is not limited to the structure in which the transistor 600a and the transistor 600b each include an OS transistor. That is, the structure is not limited to the structure in which each of the oxide 650a and the oxide 650b includes an oxide semiconductor. Thus, in this specification and the like, "oxide" can be appropriately replaced with "semiconductor", "semiconductor layer", or "semiconductor film".

[0101] Since the oxide semiconductor that forms a channel has a band gap of 2 eV or more, an OS transistor has a characteristic of having extremely small off-state current. The off-state current value of an OS transistor per 1 μm of channel width in a room-temperature environment can be 1 aA (1 x 10 -18 A) or less, 1 zA (1 x 10 -21 A) or less, or 1 yA (1 x 10 -24 A) or less. Note that in a Si transistor (a transistor including silicon in a channel formation region), the off-state current value per 1 μm of channel width in a room-temperature environment is 1 fA (1 x 10 -15 A) or more and 1 pA (1 x 10 -12 A) or less. Thus, it can be said that the off-state current of an OS transistor is smaller than that of a Si transistor by about 10 digits. Thus, for example, when a wiring connected to one of a source and a drain of an OS transistor is in a floating state, the charge stored in the wiring can be kept for a long time. Thus, for example, by using an OS transistor to form a memory cell, data written to the memory cell can be stored for a long time.

[0102] Further, the off-state current of the OS transistor hardly increases even in a high-temperature environment. Specifically, the off-state current hardly increases even in an environment of 2000C or lower and higher than room temperature. Further, the on-state current of the OS transistor does not easily decrease even in a high-temperature environment. On the other hand, the on-state current of the Si transistor decreases in a high-temperature environment. That is, the on-state current of the OS transistor is larger than that of the Si transistor in a high-temperature environment. Further, the ratio of the on-state current to the off-state current of the OS transistor is large even in an environment of 1500C or lower and higher than 1250C, and thus good switching operation can be performed. Therefore, the semiconductor device using the OS transistor stably operates and has high reliability even in a high-temperature environment.

[0103] Further, the withstand voltage between the source and the drain of the OS transistor (also referred to as drain withstand voltage) is high. Therefore, the semiconductor device using the OS transistor stably operates and has high reliability even when driven with a high voltage.

[0104] Therefore, in the semiconductor device 100, by using the OS transistor for both the transistor 600a and the transistor 600b, damage of the transistor 600a and the transistor 600b themselves due to a surge generated by ESD or the like can be suppressed. Therefore, the reliability of the semiconductor device 100 can be improved.

[0105] Further, since the off-state current of the OS transistor is extremely small, the current flowing from the wiring SIG to the wiring VLD and the current flowing from the wiring SIG to the wiring VLS can be made extremely small at the time of normal operation (here, a case where the potential of the wiring SIG is a potential VSS or higher and a potential VDD or lower and both the transistor 600a and the transistor 600b are in an off state). Therefore, the power consumption of the semiconductor device 100 can be suppressed from increasing.

[0106] Further, for example, in a memory device or the like using a memory cell including an OS transistor, when the semiconductor device 100 having a function of an ESD protection circuit is provided in the memory device, at least one of the transistor 600a and the transistor 600b can be manufactured at the same time as the OS transistor included in the memory cell. Therefore, no additional process or additional mask or the like is needed, and thus the semiconductor device 100 can be provided to improve the reliability of the memory device without increasing the process cost.

[0107] That is, for example, in a memory device or the like using a memory cell including an OS transistor, when an ESD protection circuit is provided in the memory device, by adopting a structure like the semiconductor device 100, the reliability of the memory device can be improved while suppressing an increase in power consumption, an increase in process cost, and an increase in occupied area.

[0108] [Transistor 600]

[0109] Next, the specific structure of the transistor 600a and the transistor 600b is described. Note that in the following description, common parts between the transistor 600a and the transistor 600b are described with the transistor 600 as an example. That is, a part of the insulator 640a, the conductor 660a, the oxide 650a, the insulator 672a, and the conductor 670a (here, a region where the conductor 670a is in contact with the insulator 672a and a region in the vicinity thereof) in the transistor 600a each corresponds to the insulator 640, the conductor 660, the oxide 650, the insulator 672, and the conductor 670. Further, a part of the conductor 670a (here, a region where the conductor 670a is in contact with the oxide 650b and a region in the vicinity thereof), the insulator 640b, the conductor 660b, the oxide 650b, the insulator 672b, and the conductor 670b in the transistor 600b each correspond to the conductor 630, the insulator 640, the conductor 660, the oxide 650, the insulator 672, and the conductor 670.

[0110] The transistor 600 includes the conductor 630, the insulator 640, the conductor 660 over the insulator 640, the oxide 650, the insulator 672 over the oxide 650, and the conductor 670 over the insulator 672. The oxide 650 is used as a semiconductor film including a channel formation region, the conductor 670 is used as a gate electrode, the insulator 672 is used as a gate insulating film, the conductor 630 is used as one of a source electrode and a drain electrode, and the conductor 660 is used as the other of the source electrode and the drain electrode.

[0111] In the transistor 600, a metal oxide used as an oxide semiconductor is used as the oxide 650 including a channel formation region.

[0112] The metal oxide preferably contains at least one of indium and zinc. For example, indium, M (M is one or more selected from gallium, aluminum, yttrium, tin, silicon, boron, copper, vanadium, beryllium, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, magnesium, and cobalt), and zinc are preferably contained. In particular, M is preferably one or more selected from gallium, aluminum, yttrium, and tin.

[0113] In particular, as the metal oxide, an oxide containing indium (In), gallium (Ga), and zinc (Zn) (also referred to as IGZO) is preferably used. Alternatively, an oxide containing indium (In), aluminum (Al), and zinc (Zn) (also referred to as IAZO) can be used. Alternatively, an oxide containing indium (In), aluminum (Al), gallium (Ga), and zinc (Zn) (also referred to as IAGZO) can be used. Alternatively, an oxide containing indium (In), tin (Sn), and zinc (Zn) (also referred to as "ITZO (registered trademark)") can be used. Alternatively, an oxide containing indium (In), gallium (Ga), zinc (Zn), and tin (Sn) (also referred to as "IGZTO") can be used.

[0114] By increasing the proportion of the number of atoms of indium in the metal oxide in the total number of atoms of all metal elements, favorable characteristics such as a high on-state current, a high field-effect mobility, and high frequency characteristics can be obtained in a transistor in which the metal oxide is used for a semiconductor film including a channel formation region.

[0115] In the case where the metal oxide is an In-M-Zn oxide, the proportion of the number of atoms of In in the In-M-Zn oxide is preferably higher than that of M. As the proportion of the number of atoms of metal elements in the In-M-Zn oxide, for example, a composition of In:M:Zn = 1:1:1 or its neighborhood, a composition of In:M:Zn = 1:1:1.2 or its neighborhood, a composition of In:M:Zn = 2:1:3 or its neighborhood, a composition of In:M:Zn = 3:1:2 or its neighborhood, a composition of In:M:Zn = 4:2:3 or its neighborhood, a composition of In:M:Zn = 4:2:4.1 or its neighborhood, a composition of In:M:Zn = 5:1:3 or its neighborhood, a composition of In:M:Zn = 5:1:6 or its neighborhood, a composition of In:M:Zn = 5:1:7 or its neighborhood, a composition of In:M:Zn = 5:1:8 or its neighborhood, a composition of In:M:Zn = 6:1:6 or its neighborhood, or a composition of In:M:Zn = 5:2:5 or its neighborhood, or the like can be given. Note that the proportion of the number of atoms of In in the In-M-Zn oxide can be smaller than that of M. As the proportion of the number of atoms of metal elements in the In-M-Zn oxide, for example, a composition of In:M:Zn = 1:3:2 or its neighborhood, a composition of In:M:Zn = 1:3:4 or its neighborhood, or the like can be given. Note that the neighborhood composition includes a range of ±30% of the desired proportion of the number of atoms.

[0116] For example, when the composition is described as having an atomic ratio of metal elements of In:Ga:Zn = 4:2:3 or the vicinity thereof, the content ratio of each element includes the following cases: when In is 4, Ga is 1 or more and 3 or less, and Zn is 2 or more and 4 or less. Further, when the composition is described as having an atomic ratio of metal elements of In:Ga:Zn = 5:1:6 or the vicinity thereof, the content ratio of each element includes the following cases: when In is 5, Ga is more than 0.1 and 2 or less, and Zn is 5 or more and 7 or less. Further, when the composition is described as having an atomic ratio of metal elements of In:Ga:Zn = 1:1:1 or the vicinity thereof, the content ratio of each element includes the following cases: when In is 1, Ga is more than 0.1 and 2 or less, and Zn is more than 0.1 and 2 or less.

[0117] Further, when the metal oxides are stacked, for example, a three-layer structure can be given in which a metal oxide having an atomic ratio of metal elements of In:Ga:Zn = 1:1:1 is provided as a first layer, a metal oxide having an atomic ratio of metal elements of In:Zn = 4:1 is provided as a second layer, and a metal oxide having an atomic ratio of metal elements of In:Ga:Zn = 1:1:1 is provided as a third layer. It is preferable that the band gap of the metal oxide of the first layer and the third layer be larger than the band gap of the metal oxide of the second layer. By adopting this structure, the metal oxide of the second layer can be used as a main current path, and thus a so-called embedded channel structure can be realized.

[0118] As an analysis of the composition of the metal oxide, for example, secondary ion mass spectrometry (SIMS), 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), or the like can be used. Further, a plurality of the above-described methods can be combined and used for analysis. Note that an element having a low content ratio is sometimes different from the actual content ratio due to the analysis accuracy. For example, when the content ratio of an element M is low, the content ratio of the element M obtained by analysis is sometimes lower than the actual content ratio.

[0119] The metal oxide can be formed using a sputtering method or an atomic layer deposition (ALD) method. Note that in the case where the metal oxide is formed using a sputtering method, the composition of the formed metal oxide is sometimes different from that of a sputtering target. In particular, the content of zinc in the formed metal oxide is sometimes reduced to about 50 % of that in the sputtering target.

[0120] The oxide semiconductor preferably has crystallinity. As the oxide semiconductor having crystallinity, a CAAC-OS (c-axis aligned crystalline oxide semiconductor), an nc-OS (nanocrystalline oxide semiconductor), a polycrystalline oxide semiconductor, a single crystal oxide semiconductor, or the like can be given. The CAAC-OS or the nc-OS is preferably used as the oxide semiconductor, and particularly the CAAC-OS is preferably used.

[0121] The CAAC-OS preferably has a plurality of layered crystal regions and has a c-axis aligned in the direction of a normal line of a formation surface. For example, the oxide semiconductor preferably has a layered crystal parallel to a formation surface. With such a structure, the layered crystal of the oxide semiconductor is parallel to the channel length direction of the transistor, so that the on-state current of the transistor can be increased.

[0122] In addition, in the deposition method of the oxide semiconductor of one embodiment of the present application, a CAAC-OS of an oxide semiconductor having high crystallinity can be used as a nucleus or seed to improve the crystallinity of the oxide semiconductor formed above and below the CAAC-OS. Thus, the crystallinity of the entire oxide semiconductor can be improved. In other words, the oxide semiconductor formed above and below the CAAC-OS is grown in a solid phase using the CAAC-OS as a nucleus or seed, so that an oxide semiconductor having high crystallinity can be formed. The oxide semiconductor formed by the deposition method can be referred to as an Axial Growth CAAC (AG CAAC).

[0123] By improving the crystallinity of the oxide semiconductor, a transistor including a semiconductor film including a channel formation region using the oxide semiconductor can have excellent characteristics (e.g., a transistor with a large on-state current, a transistor with high field-effect mobility, a transistor with a small S value, a transistor with high frequency characteristics (also referred to as f characteristics), a transistor with high reliability, or the like).

[0124] After the deposition of the oxide semiconductor, or after the deposition of the oxide semiconductor, treatment for increasing the crystallinity of the oxide semiconductor is preferably performed. As the treatment for increasing the crystallinity of the oxide semiconductor, for example, a heat treatment, a plasma treatment, a microwave (typically, 2.45 GHz) treatment, a microwave plasma treatment, and a light (e.g., ultraviolet light) irradiation treatment can be given. Note that a plurality of the above treatments can be performed at the same time or in order. For example, a heat treatment and a microwave plasma treatment can be performed at the same time. Alternatively, a microwave plasma treatment can be performed after a heat treatment.

[0125] In this specification and the like, a microwave refers to an electromagnetic wave having a frequency of 300 MHz or more and 300 GHz or less. A microwave plasma treatment refers to a treatment using a device including a power source for generating high-density plasma by means of a microwave, for example. The microwave plasma treatment can also be referred to as a microwave-excited high-density plasma treatment.

[0126] Further, it is more preferable that the treatment for increasing the crystallinity of the oxide semiconductor be performed a plurality of times while the oxide semiconductor is deposited. For example, in the case where an oxide semiconductor film is formed by an ALD method, a microwave plasma treatment is preferably performed each time an atomic layer is formed. Alternatively, by performing the treatment for increasing the crystallinity each time an oxide semiconductor layer having a thickness in a predetermined range is formed, the productivity can be increased, and thus this is preferable. Specifically, it is preferable that a first oxide semiconductor film be formed to a thickness of greater than or equal to 1 nm and less than or equal to 10 nm and a first microwave plasma treatment be performed, and then a second oxide semiconductor film be formed to a thickness of greater than or equal to 1 nm and less than or equal to 10 nm and a second microwave plasma treatment be performed. Note that there is no particular limitation on the deposition method of the first oxide semiconductor film and the second oxide semiconductor film, and an ALD method or a sputtering method can be used for each of them. In particular, by depositing the first oxide semiconductor film using an ALD method, an element included in a layer constituting a surface to be formed can be prevented from being mixed in (also referred to as mixed) the first oxide semiconductor film and the second oxide semiconductor film, and thus this is preferable. In particular, this is suitable for a case where the element included in the layer constituting the surface to be formed inhibits crystallization of the oxide semiconductor (e.g., a case where silicon, carbon, or the like is included). Further, the first oxide semiconductor film and the second oxide semiconductor film can have different compositions from each other. Further, a stacked structure of the first oxide semiconductor film and the second oxide semiconductor film is shown here, but is not limited thereto. The same treatment can be employed even when the oxide semiconductor film has a single-layer structure or a stacked structure of three or more layers.

[0127] Furthermore, the treatment to improve the crystallinity of the oxide semiconductor can also be performed after the oxide semiconductor is deposited. Specifically, this treatment can be performed directly on the deposited oxide semiconductor or in the presence of other films, such as insulating films, deposited on the oxide semiconductor. For example, microwave plasma treatment can be performed after the oxide semiconductor is deposited, or an insulating film (e.g., silicon nitride film, silicon oxide film, aluminum oxide film, etc.) can be deposited after the oxide semiconductor is deposited, and then the oxide semiconductor is subjected to heat treatment or microwave plasma treatment in the presence of the insulating film.

[0128] Note that the above-described treatment for improving the crystallinity of oxide semiconductors can also serve as a treatment for removing impurities from the oxide semiconductor. For example, carbon, hydrogen, nitrogen, etc., can be appropriately removed from the oxide semiconductor. Alternatively, by performing the treatment for improving the crystallinity of the oxide semiconductor under an oxygen gas atmosphere, oxygen vacancies in the oxide semiconductor can be reduced.

[0129] When performing a process to improve the crystallinity of oxide semiconductors, it is preferable to set the substrate temperature to room temperature (e.g., 25°C) or higher, 100°C or higher and 600°C or lower, or 300°C or higher and 450°C or lower. Furthermore, the temperature for the heat treatment is preferably 100°C or higher and 700°C or lower, or 300°C or higher and 450°C or lower.

[0130] By increasing the crystallinity of oxide semiconductors, transistors with high reliability can be achieved.

[0131] The crystallinity of oxide semiconductors can be analyzed, for example, by X-ray diffraction (XRD) patterns, transmission electron microscopy (TEM) images, or electron diffraction (ED) patterns. Furthermore, multiple methods can be combined for analysis.

[0132] like Figure 1B and Figure 1C As shown, an opening 648 is provided in the insulator 640 and the conductor 660, leading to the conductor 630. At least a portion of the oxide 650 is disposed in the opening 648. Note that the oxide 650 has a region in the opening 648 that contacts the top surface of the conductor 630, a region in the opening 648 that contacts the side surface of the conductor 660, and a region that contacts at least a portion of the top surface of the conductor 660. The insulator 672 is disposed such that at least a portion of it is located in the opening 648. The conductor 670 is disposed such that at least a portion of it is located in the opening 648. Furthermore, as... Figure 1B and Figure 1CAs shown, the conductive body 670 is preferably provided so as to be embedded in the opening 648.

[0133] As the conductive body 630, for example, a structure in which titanium nitride is stacked with tantalum nitride thereon can also be employed. In this case, the structure can also be employed in such a manner that the titanium nitride is in contact with the insulator below the conductive body 630 and the tantalum nitride is in contact with the oxide 650. By employing such a structure, the conductive body 630 can be inhibited from being excessively oxidized due to the oxide 650. Further, when an oxide insulator is used as the insulator below the conductive body 630, the conductive body 630 can be inhibited from being excessively oxidized due to the oxide insulator. Further, as the conductive body 630, for example, a structure in which titanium nitride is stacked with tungsten thereon can also be employed.

[0134] Further, because the conductive body 630 has a region in contact with the oxide 650, a conductive material containing oxygen is preferably used. By employing such a structure, even if the conductive body 630 absorbs oxygen, the conductivity can be maintained. Further, in the case where the insulator below the conductive body 630 uses a material containing oxygen, the conductivity of the conductive body 630 can also be maintained.

[0135] As the conductive body 630, for example, indium tin oxide (also referred to as ITO), indium tin oxide to which silicon is added (also referred to as ITSO), indium zinc oxide (also referred to as IZO (registered trademark)), or the like can be used in a single layer or a stacked layer.

[0136] The oxide 650 has a region in contact with a side surface of the conductive body 660 in the opening 648 and a region in contact with a part of a top surface of the conductive body 660. Thus, by the oxide 650 being in contact with the top surface of the conductive body 660 in addition to the side surface thereof, the contact area of the oxide 650 with the conductive body 660 can be increased.

[0137] Further, Figure 1C A structure in which the side end portion of the oxide 650 is positioned inside the side end portion of the conductive body 660 is shown. Note that one embodiment of the present application is not limited to this. For example, a structure in which the side end portion of the oxide 650 coincides with the side end portion of the conductive body 660 in at least one of the X direction and the Y direction can also be employed. Alternatively, a structure in which the side end portion of the oxide 650 is positioned outside the side end portion of the conductive body 660 can also be employed.

[0138] A side surface of the opening 648 (sometimes referred to as a side surface of the opening 648 in the insulator 640) is preferably perpendicular to the top surface of the conductive body 630. In other words, the insulator 640 can also be said to include the opening 648 extending in a direction perpendicular to the top surface of the conductive body 630. At this time, the opening 648 has a cylindrical shape.

[0139] Note that the shape of the opening 648 in plan view is illustrated as a circular shape in this example, but one embodiment of the present application is not limited to this. For example, the shape of the opening 648 in plan view can be a substantially circular shape such as an elliptical shape, a polygonal shape such as a quadrangular shape, or a shape in which the corners of a polygonal shape are rounded. In this case, the maximum width of the opening 648 can be appropriately calculated depending on the shape in plan view of the uppermost part of the opening 648.

[0140] For example, when the opening 648 is a quadrangular shape in plan view, the maximum width of the opening 648 can be the length of the diagonal of the quadrangular shape. Alternatively, for example, when the opening 648 has a substantially circular shape such as an elliptical shape, a polygonal shape, or a shape in which the corners of a polygonal shape are rounded, the maximum width of the opening 648 can be the maximum width of the shape in plan view of the opening 648.

[0141] The arrangement of the oxide 650, the insulator 672, and the conductor 670 in the portion of the opening 648 reflects the shape of the opening 648. Thus, the oxide 650 is provided along the side surface of the opening 648, the insulator 672 is provided so as to cover the oxide 650, and the conductor 670 is provided so as to fit in the recess of the insulator 672 which reflects the shape of the opening 648. In other words, part of the conductor 670 has a shape along the side surface of the oxide 650 inside the opening 648.

[0142] That is, part of the semiconductor film (corresponding to the oxide 650) of the transistor 600 including the channel formation region is provided along the side surface of the opening 648. In other words, it is provided in a direction perpendicular to the top surface of the conductor 630. In other words, the channel length direction of the transistor 600 has a component in a direction perpendicular to the top surface of the conductor 630.

[0143] Here, the insulator 672 is preferably formed using an insulator containing excess oxygen and releasing oxygen by heating. Thus, oxygen can be efficiently supplied from the insulator 672 to the channel formation region of the oxide 650.

[0144] As the insulator 672, a material used for the insulator 522, the insulator 524, or the insulator 545 to be described later can be used, for example. For example, silicon oxide, silicon oxynitride, silicon nitride oxide, silicon nitride, silicon oxide to which fluorine is added, silicon oxide to which carbon is added, silicon oxide to which carbon and nitrogen are added, or silicon oxide having a void can be used. In particular, from the viewpoint of heat resistance, silicon oxide or silicon oxynitride is preferably used. In addition, an insulator in which the concentration of impurities such as hydrogen and water is reduced is preferably used.

[0145] Further, the conductive body 630, the conductive body 660, and the conductive body 670 preferably use a single layer or a stack of a conductive material. For example, a conductive material that is not easily oxidized or a conductive material that has a function of suppressing diffusion of oxygen, or the like is preferably used.

[0146] As the conductive body 630, the conductive body 660, and the conductive body 670, for example, a material that can be used for the conductive body 503, the conductive body 560, or the conductive body 542a and the conductive body 542b described later can be used. For example, titanium nitride, tantalum nitride, or the like can be used. Further, for example, from the viewpoint of conductivity and heat resistance, a stack of tungsten is preferably used.

[0147] The insulator 640 is used as an interlayer film, and thus a material with a low relative dielectric constant is preferably used. By using a material with a low relative dielectric constant for the interlayer film, parasitic capacitance generated between wirings can be reduced. The insulator 640 can use a single layer or a stack of an insulator including a material with a low relative dielectric constant.

[0148] As the insulator 640, for example, a material that can be used for the insulator 516 described later can be used. For example, from the viewpoint of having heat stability, silicon oxide or silicon oxynitride is preferably used.

[0149] As the insulator 620 and the insulator 678, an insulator having a barrier property against oxygen, hydrogen, or the like is preferably used. For example, an insulator having a barrier property that can prevent impurities such as hydrogen from diffusing into a region where the transistor 600 is provided from the outside or the like of the region where the transistor 600 is provided is preferably used.

[0150] As the insulator 620 and the insulator 678, for example, a material that can be used for the insulator 514 described later can be used. For example, from the viewpoint of having a barrier property against hydrogen, a metal oxide such as aluminum oxide, hafnium oxide, tantalum oxide, or the like is preferably used.

[0151] Note that the opening 648 is provided so that a side surface of the opening 648 is perpendicular to a top surface of the conductive body 630 in the Figure 1B and Figure 1C However, the present application is not limited thereto. For example, the side surface of the opening 648 can have a tapered shape.

[0152] In this specification and the like, a tapered shape means a shape in which at least a part of a side surface of a component is provided to be inclined with respect to a substrate surface. Further, an angle formed by the inclined side surface and the substrate surface is referred to as a taper angle. In particular, in this specification and the like, a tapered shape having a taper angle of more than 0° and less than 90° is sometimes referred to as a positive taper shape, and a tapered shape having a taper angle of more than 90° and less than 180° is sometimes referred to as a reverse taper shape.

[0153] Further, in the Figure 1B and Figure 1C The structure in which the oxide 650 is a single layer is shown, but one embodiment of the present application is not limited to this. The oxide 650 can have a stacked-layer structure of a plurality of oxide layers having different chemical compositions.

[0154] Figure 2A is Figure 1B is an enlarged view of the oxide 650 and its vicinity in FIG. 6B. Figure 2B is a cross-sectional view of a portion along the dot-dash line of A5-A6 in FIG. 6B. Figure 2A

[0155] As shown in FIG. 6A, the oxide 650 has a region 650i, a region 650na provided so as to sandwich the region 650i, and a region 650nb. Figure 2A The region 650na is a region of the oxide 650 which is in contact with the conductor 630. At least a part of the region 650na is used as one of a source region and a drain region of the transistor 600. The region 650nb is a region of the oxide 650 which is in contact with the conductor 660. At least a part of the region 650nb is used as the other of the source region and the drain region of the transistor 600. As shown in FIG. 6A, the conductor 660 is in contact with the entire outer periphery of the oxide 650. Thus, the other of the source region and the drain region of the transistor 600 is likely to be formed in the entire outer periphery of the portion of the oxide 650 which is formed in the same layer as the conductor 660.

[0156] Figure 2B

[0157] The region 650i is a region of the oxide 650 between the region 650na and the region 650nb. At least a part of the region 650i is used as a channel formation region of the transistor 600. That is, the channel formation region of the transistor 600 is positioned in the region of the oxide 650 between the conductor 630 and the conductor 660. Further, it can be said that the channel formation region of the transistor 600 is positioned in the region of the oxide 650 which is in contact with the insulator 640 or a region in the vicinity thereof.

[0158] The channel length of the transistor 600 is the distance between the source region and the drain region. That is, the channel length of the transistor 600 is determined depending on the thickness of the insulator 640 over the conductor 630. In Figure 2A

[0159] ​​​​In this case, in the planar transistor, the channel length is set in accordance with the exposure limit of photolithography, but in one embodiment of the present application, the channel length can be set in accordance with the thickness of the insulator 640. Therefore, the channel length of the transistor 600 can be set to a very fine structure (e.g., 60 nm or less, 50 nm or less, 40 nm or less, 30 nm or less, 20 nm or less, or 10 nm or less and 1 nm or more or 5 nm or more) below the exposure limit of photolithography. Thus, the on-state current of the transistor 600 is increased, and thus the frequency characteristics can be improved.

[0160] Further, as described above, the channel formation region, the source region, and the drain region can be formed in the opening 648. Therefore, as compared with the planar transistor in which the channel formation region, the source region, and the drain region are separately provided in the XY plane, the area occupancy of the transistor 600 can be reduced.

[0161] Further, as compared with Figure 2B Similarly, in the XY plane of the channel formation region including the oxide 650, the oxide 650, the insulator 672, and the conductor 670 are also provided in a concentric circular shape. Therefore, the side surface of the conductor 670 provided at the center faces the side surface of the oxide 650 with the insulator 672 interposed therebetween. In other words, the entire outer periphery of the oxide 650 becomes the channel formation region when viewed in plan view. At this time, for example, the channel width of the transistor 600 is determined in accordance with the length of the outer periphery of the oxide 650. In other words, the channel width of the transistor 600 is determined in accordance with the size of the maximum width of the opening 648 (in the case where the shape of the opening 648 in plan view is circular, the maximum diameter). Figure 2A and Figure 2B In the drawing, the maximum width D of the opening 648 is indicated by a double-headed arrow with a double-dot chain line. In the drawing, the channel width W of the transistor 600 is indicated by a double-headed arrow with a dot chain line. By increasing the size of the maximum width D of the opening 648, the channel width per unit area can be increased, and thus the on-state current can be increased. Figure 2B

[0162] When the opening 648 is formed by photolithography, the maximum width D of the opening 648 is set in accordance with the exposure limit of photolithography. Further, the maximum width D of the opening 648 is set in accordance with the thicknesses of the oxide 650, the insulator 672, and the conductor 670 provided in the opening 648. The maximum width D of the opening 648 is preferably, for example, 5 nm or more, 10 nm or more, or 20 nm or more and 100 nm or less, 60 nm or less, 50 nm or less, 40 nm or less, or 30 nm or less. Note that in the case where the shape of the opening 648 in plan view is circular, the maximum width D of the opening 648 corresponds to the diameter of the opening 648, and the channel width W can be calculated as "D x π".

[0163] ​Further, the channel length L of the transistor 600 of one embodiment of the present application is preferably less than the channel width W of the transistor 600. The channel length L of the transistor 600 of one embodiment of the present application is greater than or equal to 0.1 times and less than or equal to 0.99 times the channel width W of the transistor 600, preferably greater than or equal to 0.5 times and less than or equal to 0.8 times the channel width W. With such a structure, a transistor with good electrical characteristics and high reliability can be implemented.

[0164] Further, by forming the opening 648 in a manner that has a circular shape in plan view, the oxide 650, the insulator 672, and the conductor 670 are arranged in a concentric circular shape. Thus, the distance between the conductor 670 and the oxide 650 is uniform, so that a gate electric field can be uniformly applied to the oxide 650.

[0165] Note that, Figures 1A to 1C The transistor 600 illustrated is just an example and is not limited to the above structure.

[0166] [Modified Example 1]

[0167] Figure 3A , Figure 3B and Figure 6A is a top view, a cross-sectional view, and a circuit diagram of a structure example of a semiconductor device 100<2> which is a modified example of the above semiconductor device 100. The semiconductor device 100<2> is a structure example in which an ESD protection circuit like the above semiconductor device 100 is provided for each of two wirings SIG (wiring SIG[1] and wiring SIG[2]) having a function of a signal line. Thus, the description of the above semiconductor device 100 can be referred to as appropriate, and thus the description thereof is sometimes omitted here.

[0168] Figure 3A is a top view of the semiconductor device 100<2>. Figure 3B is a cross-sectional view of a portion indicated by a dot-and-dash line A1-A2 in Figure 3A Note that, in the top view of Figure 3A , part of the components is omitted for clarity. In addition, a cross-sectional view of a portion indicated by a dot-and-dash line A3-A4 and a cross-sectional view of a portion indicated by a dot-and-dash line A3'-A4' in Figure 3A may be referred to as appropriate. Figure 1C

[0169] Figure 3A and Figure 3B show the transistor 600a[1] and the transistor 600b[1] which have a function of an ESD protection diode for one of the two wirings SIG (wiring SIG[1]). In addition, the transistor 600a[2] and the transistor 600b[2] which have a function of an ESD protection diode for the other of the two wirings SIG (wiring SIG[2]) are also shown.​

[0170] In addition, in Figure 3A and Figure 3B , as one example, the conductive body 670a[1], the transistor 600a[1], and the transistor 600b[1] and the like which correspond to the wiring SIG[1] are arranged in the X direction together with the conductive body 670a[2], the transistor 600a[2], and the transistor 600b[2] and the like which correspond to the wiring SIG[2].

[0171] Here, the transistor 600a[1] and the transistor 600a[2] each correspond to the above-described transistor 600a. The transistor 600b[1] and the transistor 600b[2] each correspond to the above-described transistor 600b. Thus, the opening 648a[1] and the opening 648a[2] each correspond to the opening 648a, the oxide 650a[1] and the oxide 650a[2] each correspond to the oxide 650a, the conductive body 660a[1] and the conductive body 660a[2] each correspond to the conductive body 660a, the conductive body 670a[1] and the conductive body 670a[2] each correspond to the conductive body 670a, the opening 648b[1] and the opening 648b[2] each correspond to the opening 648b, the oxide 650b[1] and the oxide 650b[2] each correspond to the oxide 650b. The opening 676a[1] and the opening 676a[2] each correspond to the opening 676a.

[0172] As shown in Figure 3A and Figure 3B , the conductive body 630 extends in the X direction and includes a region serving as one of a source electrode and a drain electrode of the transistor 600a[1] and a region serving as one of a source electrode and a drain electrode of the transistor 600a[2]. The conductive body 670a[1] extends in the Y direction and is in contact with the conductive body 660a[1] through the opening 676a[1] provided in the insulator 672a. The conductive body 670a[2] extends in the Y direction and is in contact with the conductive body 660a[2] through the opening 676a[2] provided in the insulator 672a. The conductive body 660b includes a region serving as the other of a source electrode and a drain electrode of the transistor 600b[1] and a region serving as the other of a source electrode and a drain electrode of the transistor 600b[2]. The conductive body 670b extends in the X direction and includes a region serving as a gate electrode of the transistor 600b[1] and a region serving as a gate electrode of the transistor 600b[2]. Further, the conductive body 670b is in contact with the conductive body 660b through the opening 676b provided in the insulator 672b.

[0173] Here, Figure 6AThe circuit diagram shown shows transistor Mll[l] corresponding to transistor 600a[l], transistor M12[l] corresponding to transistor 600b[l], transistor Mll[2] corresponding to transistor 600a[2], and transistor M12[2] corresponding to transistor 600b[2]. One of the source and drain of transistor Mll[l] is connected to the wiring VLD. The other of the source and drain of transistor Mll[l] is connected to the gate of transistor Mll[l], one of the source and drain of transistor M12[l], and the wiring SIG[l]. The other of the source and drain of transistor M12[l] is connected to the gate of transistor M12[l] and the wiring VLS. One of the source and drain of transistor Mll[2] is connected to the wiring VLD. The other of the source and drain of transistor Mll[2] is connected to the gate of transistor Mll[2], one of the source and drain of transistor M12[2], and the wiring SIG[2]. The other of the source and drain of transistor M12[2] is connected to the gate of transistor M12[2] and the wiring VLS.

[0174] The wiring VLD corresponds to the conductor 630. The wiring SIG[l] corresponds to the conductor 660a[l] and the conductor 670a[l]. The wiring SIG[2] corresponds to the conductor 660a[2] and the conductor 670a[2]. The wiring VLS corresponds to the conductor 660b and the conductor 670b. Note that in Figure 3A and Figure 3B the conductor corresponding to each of the wiring VLD, the wiring SIG[l], the wiring SIG[2], and the wiring VLS is given a symbol in parentheses.

[0175] Here, in the semiconductor device 100<2>, as with the semiconductor device 100 described above, the transistor 600a[l] and the transistor 600b[l] each having a function of an ESD protection diode can be arranged so as to overlap the wiring SIG[l] having a function of a signal line, and the transistor 600a[2] and the transistor 600b[2] each having a function of an ESD protection diode can be arranged so as to overlap the wiring SIG[2] having a function of a signal line.

[0176] For example, when viewed from above, there is no need to provide a region for arranging the transistor 600a[l], the transistor 600b[l], the transistor 600a[2], and the transistor 600b[2], each having a function of an ESD protection diode, between the conductor 670a[l] corresponding to the wiring SIG[l] and the conductor 670a[2] corresponding to the wiring SIG[2], so the conductor 670a[l] and the conductor 670a[2] can be arranged at the minimum interval of a design rule. Thus, the ESD protection circuit can be provided without a large increase in the area occupancy.

[0177] Therefore, for example, in a memory device using a memory cell including an OS transistor, when a plurality of ESD protection circuits are provided in the memory device, by adopting the structure of the semiconductor device 100<2>, it is possible to improve the reliability of the memory device while suppressing an increase in power consumption, an increase in process cost, and an increase in occupied area.

[0178] Note that although an example in which the number of wirings SIG having the function of a signal line is two is described here, the conductive body 670a corresponding to each wiring SIG can be arranged at the minimum interval of a design rule in a structure in which the number of wirings SIG having the function of a signal line is three or more, as in the semiconductor device 100<2>. Thus, it is possible to provide an ESD protection circuit without greatly increasing the occupied area, and thus it is possible to improve the reliability.

[0179] [Modified Example 2]

[0180] Figure 4A 、 Figure 4B and Figure 6B is a top view, a cross-sectional view, and a circuit diagram of a structure example of a semiconductor device 100A which is a modified example of the above-described semiconductor device 100. The semiconductor device 100A differs from the semiconductor device 100 in that the semiconductor device 100A includes two transistors 600a (a transistor 600a_1 and a transistor 600a_2) connected in parallel and two transistors 600b (a transistor 600b_1 and a transistor 600b_2) connected in parallel. Thus, the description of the above-described semiconductor device 100 can be appropriately referred to, and thus detailed description is sometimes omitted here.

[0181] Figure 4A is a top view of the semiconductor device 100A. Figure 4B is a cross-sectional view of a portion indicated by a dot-dash line A3-A4 in Figure 4A . Note that in the top view of Figure 4A , part of the components is omitted for clarity. In addition, the cross-sectional view of a portion indicated by a dot-dash line A1-A2 and the cross-sectional view of a portion indicated by a dot-dash line A1'-A2' in Figure 4A may be appropriately referred to Figure 1B .

[0182] In Figure 4A and Figure 4B , as one example, the transistor 600a_1 and the transistor 600b_1 and the like are arranged in the Y direction together with the transistor 600a_2 and the transistor 600b_2 and the like.

[0183] Here, the transistor 600a_1 and the transistor 600a_2 each correspond to the transistor 600a described above. The transistor 600b_1 and the transistor 600b_2 each correspond to the transistor 600b described above. Thus, the opening 648a_1 and the opening 648a_2 each correspond to the opening 648a, the oxide 650a_1 and the oxide 650a_2 each correspond to the oxide 650a, the opening 648b_1 and the opening 648b_2 each correspond to the opening 648b, the oxide 650b_1 and the oxide 650b_2 each correspond to the oxide 650b, and the conductive body 660b_1 and the conductive body 660b_2 each correspond to the conductive body 660b. The opening 676b_1 and the opening 676b_2 each correspond to the opening 676b.

[0184] As Figure 4A and Figure 4B indicated, the conductive body 630 extends in the X direction and includes a region serving as one of a source electrode and a drain electrode of the transistor 600a_1 and a region serving as one of a source electrode and a drain electrode of the transistor 600a_2. The conductive body 660a includes a region serving as the other of the source electrode and the drain electrode of the transistor 600a_1 and a region serving as the other of the source electrode and the drain electrode of the transistor 600a_2. The conductive body 670a extends in the Y direction and includes a region serving as a gate electrode of the transistor 600a_1 and a region serving as a gate electrode of the transistor 600a_2. Further, the conductive body 670a is in contact with the conductive body 660a through the opening 676a provided in the insulator 672a. The conductive body 670b extends in the X direction and includes a region serving as a gate electrode of the transistor 600b_1 and a region serving as a gate electrode of the transistor 600b_2. Further, the conductive body 670b is in contact with the conductive body 660b_1 through the opening 676b_1 provided in the insulator 672b and in contact with the conductive body 660b_2 through the opening 676b_2 provided in the insulator 672b.

[0185] Here, Figure 6BThe circuit diagram shown shows a transistor M11_1 corresponding to the transistor 600a_1, a transistor M12_1 corresponding to the transistor 600b_1, a transistor M11_2 corresponding to the transistor 600a_2, and a transistor M12_2 corresponding to the transistor 600b_2. One of the source and drain of the transistor M11_1 is connected to the wiring VLD. The other of the source and drain of the transistor M11_1 is connected to the gate of the transistor M11_1, one of the source and drain of the transistor M12_1, and the wiring SIG. The other of the source and drain of the transistor M12_1 is connected to the gate of the transistor M12_1 and the wiring VLS. One of the source and drain of the transistor M11_2 is connected to the wiring VLD. The other of the source and drain of the transistor M11_2 is connected to the gate of the transistor M11_2, one of the source and drain of the transistor M12_2, and the wiring SIG. The other of the source and drain of the transistor M12_2 is connected to the gate of the transistor M12_2 and the wiring VLS.

[0186] The wiring VLD corresponds to the conductor 630. The wiring SIG corresponds to the conductor 660a and the conductor 670a. The wiring VLS corresponds to the conductor 660b_1, the conductor 660b_2, and the conductor 670b. Note that in the Figure 4A and Figure 4B In the above-described semiconductor device 100, the conductors corresponding to each of the wiring VLD, the wiring SIG, and the wiring VLS are given symbols in parentheses.

[0187] Here, the semiconductor device 100A includes two transistors 600a (the transistor 600a_1 and the transistor 600a_2) connected in parallel and two transistors 600b (the transistor 600b_1 and the transistor 600b_2) connected in parallel, and thus the on-state current of the transistor having the function of the ESD protection diode can be increased as compared with the above-described semiconductor device 100. Thus, a surge generated in the wiring SIG due to ESD or the like can be easily released to the wiring VLD and the wiring VLS.

[0188] At this time, as with the above-described semiconductor device 100, the two transistors 600a connected in parallel and the two transistors 600b connected in parallel can be arranged so as to overlap the wiring SIG having the function of the signal line. Thus, the on-state current can be increased without significantly increasing the occupied area.

[0189] Therefore, for example, in the case where the wiring SIG is connected to other circuit (not shown), it is possible to improve the reliability of the circuit without greatly increasing the occupied area. In addition, for example, in a memory device or the like using a memory cell including an OS transistor, when an ESD protection circuit is provided in the memory device, by adopting the structure of the semiconductor device 100A, it is possible to improve the reliability of the memory device while suppressing an increase in the occupied area.

[0190] Note that although a structure example of the semiconductor device 100A including two transistors 600a connected in parallel and two transistors 600b connected in parallel is described here, a structure including three or more transistors 600a connected in parallel and three or more transistors 600b connected in parallel can be employed. Thus, it is further possible to easily release a surge generated in the wiring SIG due to ESD or the like to the wiring VLD and the wiring VLS without greatly increasing the occupied area, and thus it is possible to improve the reliability.

[0191] 〔Modified Example 3〕

[0192] Figures 5A to 5C and Figure 6C is a top view, a cross-sectional view, and a circuit diagram of a structure example of a semiconductor device 100B which is a modified example of the semiconductor device 100 described above. The semiconductor device 100B differs from the semiconductor device 100 in that the semiconductor device 100B includes a transistor 600a and a transistor 600c connected in series instead of the transistor 600a, and includes a transistor 600b and a transistor 600d connected in series instead of the transistor 600b. Therefore, the description of the semiconductor device 100 described above can be referred to as appropriate, and thus the description thereof is sometimes omitted here.

[0193] Figure 5A is a top view of the semiconductor device 100B. Figure 5B is a cross-sectional view of a portion indicated by a dot-and-dash line A1-A2 in Figure 5A . Further, in Figure 5C , a portion indicated by a dot-and-dash line A3-A4 is a cross-sectional view of a portion indicated by a dot-and-dash line A3-A4 in Figure 5A . Note that in the top view of the semiconductor device 100B, part of the components is omitted for clarity. Figure 5A

[0194] Figure 5B and Figure 5C ​The diagram shows an insulator 620, a transistor 600c on the insulator 620, a transistor 600a on the transistor 600c, a transistor 600d on the transistor 600a, a transistor 600b on the transistor 600d, an insulator 640c on the insulator 620, an insulator 640a on the insulator 640c, an insulator 640d on the insulator 640a, an insulator 640b on the insulator 640d, and an insulator 678 on the transistors 600c, 600a, 600d, and 600b. Insulators 620, 640c, 640a, 640d, 640b, and 678 all function as interlayer films and protective films.

[0195] Additionally, a conductor 630 functioning as one of the source and drain electrodes of transistor 600c, a conductor 660c functioning as the other of the source and drain electrodes, an oxide 650c functioning as a semiconductor film including a channel formation region, and an insulator 672c functioning as a gate insulating film are also shown. Furthermore, a conductor 670c functioning as the gate electrode of transistor 600c and as one of the source and drain electrodes of transistor 600a are also shown. Furthermore, a conductor 660a functioning as the other of the source and drain electrodes of transistor 600a, an oxide 650a functioning as a semiconductor film including a channel formation region, and an insulator 672a functioning as a gate insulating film are also shown. Furthermore, a conductor 670a functioning as the gate electrode of transistor 600a and as one of the source and drain electrodes of transistor 600d are also shown. Additionally, a conductor 660d, functioning as another of the source and drain electrodes of transistor 600d, an oxide 650d, functioning as a semiconductor film including a channel formation region, and an insulator 672d, functioning as a gate insulating film, are also shown. Furthermore, a conductor 670d, functioning as the gate electrode of transistor 600d and as one of the source and drain electrodes of transistor 600b, is also shown. Additionally, a conductor 660b, functioning as another of the source and drain electrodes of transistor 600b, an oxide 650b, functioning as a semiconductor film including a channel formation region, an insulator 672b, functioning as a gate insulating film, and a conductor 670b, functioning as a gate electrode, are also shown. Furthermore, conductors 630, 660a, 670a, 660b, and 670b all also have wiring functions.

[0196] like Figure 5B As shown, conductor 630 extends in the X direction. Figure 5C As shown, conductor 670a extends in the Y direction and contacts conductor 660a through an opening 676a provided in insulator 672a. Figure 5B As shown in FIG. 6A, the conductive body 670b extends in the X direction and contacts the conductive body 660b through the opening 676b provided in the insulator 672b.

[0197] The conductive body 670c contacts the conductive body 660c through the opening 676c provided in the insulator 672c. The conductive body 670d contacts the conductive body 660d through the opening 676d provided in the insulator 672d.

[0198] In other words, the transistor 600c, the transistor 600a, the transistor 600d, and the transistor 600b are each a diode-connected transistor.

[0199] Note that, as Figure 5C As shown in FIG. 6A, the conductive body 670b extends in the X direction and contacts the conductive body 660b through the opening 676b provided in the insulator 672b.

[0200] As shown in FIG. 6A, the conductive body 670b extends in the X direction and contacts the conductive body 660b through the opening 676b provided in the insulator 672b. Figure 5B and Figure 5C The insulator 640c and the conductive body 660c are provided with the opening 648c reaching the conductive body 630, and at least part of the structure of the transistor 600c is provided in the opening 648c. Further, the insulator 640a and the conductive body 660a are provided with the opening 648a reaching the conductive body 670c, and at least part of the structure of the transistor 600a is provided in the opening 648a. Further, the insulator 640d and the conductive body 660d are provided with the opening 648d reaching the conductive body 670a, and at least part of the structure of the transistor 600d is provided in the opening 648d. Further, the insulator 640b and the conductive body 660b are provided with the opening 648b reaching the conductive body 670d, and at least part of the structure of the transistor 600b is provided in the opening 648b.

[0201] Specifically, in the transistor 600c, part of the oxide 650c includes a region along the side surface of the opening 648c, a region in contact with the top surface of the conductive body 630, and a region in contact with the side surface of the conductive body 660c, and the region of the oxide 650c along the side surface of the opening 648c includes a channel formation region. Part of the insulator 672c is provided along the side surface of the oxide 650c. Part of the conductive body 670c is provided along the side surface of the insulator 672c. In other words, part of the conductive body 670c has a shape along the side surface of the oxide 650c inside the opening 648c. Further, in the transistor 600a, part of the oxide 650a includes a region along the side surface of the opening 648a, a region in contact with the top surface of the conductive body 670c, and a region in contact with the side surface of the conductive body 660a, and the region of the oxide 650a along the side surface of the opening 648a includes a channel formation region. Part of the insulator 672a is provided along the side surface of the oxide 650a. Part of the conductive body 670a is provided along the side surface of the insulator 672a. In other words, part of the conductive body 670a has a shape along the side surface of the oxide 650a inside the opening 648a. Further, in the transistor 600d, part of the oxide 650d includes a region along the side surface of the opening 648d, a region in contact with the top surface of the conductive body 670a, and a region in contact with the side surface of the conductive body 660d, and the region of the oxide 650d along the side surface of the opening 648d includes a channel formation region. Part of the insulator 672d is provided along the side surface of the oxide 650d. Part of the conductive body 670d is provided along the side surface of the insulator 672d. In other words, part of the conductive body 670d has a shape along the side surface of the oxide 650d inside the opening 648d. Further, in the transistor 600b, part of the oxide 650b includes a region along the side surface of the opening 648b, a region in contact with the top surface of the conductive body 670d, and a region in contact with the side surface of the conductive body 660b, and the region of the oxide 650b along the side surface of the opening 648b includes a channel formation region. Part of the insulator 672b is provided along the side surface of the oxide 650b. Part of the conductive body 670b is provided along the side surface of the insulator 672b. In other words, part of the conductive body 670b has a shape along the side surface of the oxide 650b inside the opening 648b.

[0202] Thus, the respective occupied areas of the transistor 600c, the transistor 600a, the transistor 600d, and the transistor 600b in plan view can be reduced in the semiconductor device 100B.

[0203] Further, as Figures 5A to 5CAs shown, transistors 600c, 600a, 600d, and 600b are arranged in a manner that shares a common structure and overlaps each other when viewed from above. Alternatively, the channel forming regions of transistor 600c in oxide 650c, transistor 600a in oxide 650a, transistor 600d in oxide 650d, and transistor 600b in oxide 650b can also be arranged in a manner that overlaps each other when viewed from above. This allows for a reduction in the area occupied by the semiconductor device 100B.

[0204] That is to say, in Figures 5A to 5C In the semiconductor device 100B shown, conductors 670b and 660b are located above conductor 670d, conductors 670d and 660d are located above conductor 670a, conductors 670a and 660a are located above conductor 670c, and conductors 670c and 660c are located above conductor 630. Furthermore, conductor 670b includes a region used for wiring and a region used as the gate electrode of transistor 600b. Conductor 670d includes a region used as one of the source and drain electrodes of transistor 600b and a region used as the gate electrode of transistor 600d. Conductor 670a includes a region used for wiring, a region used as one of the source and drain electrodes of transistor 600d, and a region used as the gate electrode of transistor 600a. Conductor 670c includes a region used as one of the source and drain electrodes of transistor 600a and a region used as the gate electrode of transistor 600c. Conductor 660b includes a region serving as another of the source and drain electrodes of transistor 600b, and a region serving as wiring. Conductor 660d includes a region serving as another of the source and drain electrodes of transistor 600d. Conductor 660a includes a region serving as another of the source and drain electrodes of transistor 600a, and a region serving as wiring. Conductor 630 includes a region serving as one of the source and drain electrodes of transistor 600c, and a region serving as wiring. Conductor 660c includes a region serving as another of the source and drain electrodes of transistor 600c. At this time, conductors 670b, 660b, 670d, 660d, 670a, 660a, 670c, 660c, and 630 include overlapping regions when viewed from above. In addition, when viewed from above, the length direction of each channel of transistors 600b, 600d, 600a and 600c is the depth direction (i.e., the Z direction).

[0205] Here, Figure 6CThe circuit diagram shown shows a transistor Ml 1 corresponding to the transistor 600a, a transistor M12 corresponding to the transistor 600b, a transistor M13 corresponding to the transistor 600c, and a transistor M14 corresponding to the transistor 600d. One of the source and drain of the transistor M13 is connected to the wiring VLD. The other of the source and drain of the transistor M13 is connected to the gate of the transistor M13 and one of the source and drain of the transistor Ml 1. The other of the source and drain of the transistor Ml 1 is connected to the gate of the transistor Ml 1, one of the source and drain of the transistor M14, and the wiring SIG. The other of the source and drain of the transistor M14 is connected to the gate of the transistor M14 and one of the source and drain of the transistor M12. The other of the source and drain of the transistor M12 is connected to the gate of the transistor M12 and the wiring VLS.

[0206] The wiring VLD corresponds to the conductor 630. The wiring SIG corresponds to the conductor 660a and the conductor 670a. The wiring VLS corresponds to the conductor 660b and the conductor 670b. Note that in the Figures 5A to 5C In the semiconductor device 100B, the conductors corresponding to each of the wiring VLD, the wiring SIG, and the wiring VLS are given the symbols in parentheses.

[0207] Here, the semiconductor device 100B includes the transistor 600a and the transistor 600c connected in series and the transistor 600b and the transistor 600d connected in series, and thus damage of the transistors each having a function of an ESD protection diode itself due to a surge caused by ESD or the like can be suppressed as compared with the above semiconductor device 100.

[0208] At this time, as with the above semiconductor device 100, the transistor 600a and the transistor 600c connected in series and the transistor 600b and the transistor 600d connected in series can be arranged so as to overlap the wiring SIG having a function of a signal line. Thus, damage of the transistors each having a function of an ESD protection diode itself due to a surge caused by ESD or the like can be suppressed without a large increase in the area occupancy.

[0209] Thus, for example, in the case where the wiring SIG is connected to another circuit (not shown), the reliability of the circuit can be improved without a large increase in the area occupancy. Further, for example, in a memory device or the like using a memory cell including an OS transistor, when an ESD protection circuit is provided in the memory device, by employing a structure like the semiconductor device 100B, the reliability of the memory device can be improved while suppressing an increase in the area occupancy.

[0210] Note that although a structure example of the semiconductor device 100B including two transistors (the transistor 600a and the transistor 600c) connected in series in place of the transistor 600a and including two transistors (the transistor 600b and the transistor 600d) connected in series in place of the transistor 600b is described here, a structure including three or more transistors connected in series in place of the transistor 600a and including three or more transistors connected in series in place of the transistor 600c can be employed. Thus, the transistor itself having the function of the ESD protection diode can be further prevented from being damaged by a surge due to ESD or the like without a large increase in the occupied area, and thus the reliability can be improved.

[0211] [Modified Example 4]

[0212] Figure 7 FIG. 10 is a cross-sectional view of a structure example of a semiconductor device 100C which is a modified example of the semiconductor device 100.

[0213] Figure 7 The semiconductor device 100C illustrated in FIG. 10 further includes a conductor 614 embedded in the insulator 672a and the insulator 640a in the semiconductor device 100 illustrated in FIG. 1, FIG. 2, FIG. 3, FIG. 4, FIG. 5, FIG. 6, FIG. 7, FIG. 8, or FIG. 9. Figure 1C The semiconductor device 100C is mainly different from the semiconductor device 100 in that the conductor 670a is not in contact with the conductor 660a in the semiconductor device 100C and the conductor 670a is in contact with the conductor 614 and the conductor 614 is in contact with the conductor 630. Thus, the description of the semiconductor device 100 can be referred to as appropriate, and thus the description thereof is omitted in some cases here.

[0214] Further, the conductor 614 has a function of a plug or a wiring. Details of the conductor having the function of the plug or the wiring will be described later.

[0215] In the semiconductor device 100C, the conductor 670a, the conductor 614, and the conductor 630 correspond to the wiring SIG. Further, the conductor 660a corresponds to the wiring VLD. Further, the conductor 670b and the conductor 660b correspond to the wiring VLS.

[0216] For example, as the semiconductor device 100, one embodiment of the present application can also form a diode-connected transistor 600a by connecting the gate of the transistor 600a (corresponding to the conductor 670a) to the other of the source and the drain of the transistor 600a (corresponding to the conductor 660a). Alternatively, as the semiconductor device 100C, for example, a diode-connected transistor 600a can be formed by connecting the gate of the transistor 600a (corresponding to the conductor 670a) to one of the source and the drain of the transistor 600a (corresponding to the conductor 630). Note that the transistor 600b is similar to the transistor 600a although not illustrated.

[0217] In addition, in the semiconductor device 100C illustrated in FIG. 6C, either the structure in which the conductor 630 extends in the Y direction instead of the conductor 670a or the structure in which both the conductor 670a and the conductor 630 extend in the Y direction can be employed. In particular, by employing the structure in which both the conductor 670a and the conductor 630 extend in the Y direction, the parasitic resistance of the wiring SIG corresponding to the conductor 670a and the conductor 630 can be reduced. By reducing the parasitic resistance of the wiring SIG, the delay time of a signal transmitted through the wiring SIG can be shortened. Figure 7 For example, in the case where the wiring SIG is connected to another circuit (not illustrated), the reduction in the operation speed of the circuit due to the provision of the semiconductor device 100C having the function of an ESD protection circuit can be suppressed.

[0218] [Transistor 600B]

[0219] One embodiment of the present application can also be used in the above semiconductor device 100 and the like, including a transistor including a back gate.

[0220] As one embodiment of the present application,

[0221] is a cross-sectional view illustrating a structure example of a transistor including a back gate. Figure 8 The transistor 600B illustrated in FIG. 6B is a modification example of the above transistor 600. The transistor 600B includes two gates (a gate and a back gate) formed opposite to each other with a channel formation region therebetween. Figure 8 The transistor 600B is different from the transistor 600 in that the transistor 600B includes a conductor 680 and an insulator 682. In the transistor 600B, the insulator 682 is provided between the insulator 640 and the oxide 650 on a side surface of the opening 648, and the conductor 680 is provided in a part of the insulator 640 so as to surround the outer periphery of the oxide 650 with the insulator 682 therebetween.

[0222]

[0223] ​Here, the conductive body 670 sometimes has a function of a first gate (also simply referred to as a gate) electrode, and the conductive body 680 sometimes has a function of a second gate (also referred to as a back gate) electrode. In this case, the insulator 672 has a function of a first gate insulating film, and the insulator 682 has a function of a second gate insulating film.

[0224] The transistor 600B is different from the transistor 600 in that the conductive body 630 has a recess at a position overlapping with the opening 648. In the transistor 600B, part of the oxide 650 and part of the insulator 682 are provided in the recess which the conductive body 630 has. At this time, the bottom surface of the oxide 650 is positioned below the bottom surface of the insulator 682.

[0225] With this structure, the area of the oxide 650 in contact with the conductive body 630 can be increased. Thus, the contact resistance between the oxide 650 and the conductive body 630 can be reduced.

[0226] Here, as the conductive body 680, for example, a material which can be used for the conductive body 670 can be used. Further, as the insulator 682, for example, a material which can be used for the insulator 672 can be used.

[0227] Here, in a transistor including a back gate, the threshold voltage shifts depending on the back gate voltage. Further, the back gate of the transistor can be connected to a gate, or one of a source and a drain, or the other of a source and a drain.

[0228] Figure 9A is a cross-sectional view illustrating a structure example in which the back gate (corresponding to the conductive body 680) of the transistor 600B is connected to the gate (corresponding to the conductive body 670) of the transistor 600B through the conductive body 614 embedded in the insulator 672 and the insulator 640. Figure 9B is a cross-sectional view illustrating a structure example in which the back gate (corresponding to the conductive body 680) of the transistor 600B is connected to the other of a source and a drain (corresponding to the conductive body 660) of the transistor 600B through the conductive body 614 embedded in the insulator 640. Figure 9C is a cross-sectional view illustrating a structure example in which the back gate (corresponding to the conductive body 680) of the transistor 600B is connected to one of a source and a drain (corresponding to the conductive body 630) of the transistor 600B through the conductive body 614 embedded in the insulator 640.

[0229] Further, the conductive body 614 has a function of a plug or a wiring. Details of the conductive body having a function of a plug or a wiring will be described later.

[0230] Figures 10A to 10D is a cross-sectional view illustrating a structure example in which the back gate (corresponding to the conductive body 680) of the transistor 600B is connected to the gate (corresponding to the conductive body 670) of the transistor 600B through the conductive body 614 embedded in the insulator 640. Figure 1D and Figures 6A to 6CEach of the transistors in the circuit diagram shown is replaced with an example of a circuit diagram of a transistor including a back gate. In Figures 10A to 10D Each of the transistors is connected to the gate of the transistor, as an example.

[0231] Thus, by connecting the back gate of the transistor to the gate, the on-state current of the transistor can be increased. Thus, a surge generated in the wiring SIG due to ESD or the like can be easily released to the wiring VLD and the wiring VLS, and reliability can be improved.

[0232] Further, although not shown, the threshold voltage can also be changed by supplying an arbitrary potential to the back gate of the transistor. For example, the on-state current can be increased by supplying a potential that makes the threshold voltage of the transistor smaller to the back gate. Thus, a surge generated in the wiring SIG due to ESD or the like can be easily released to the wiring VLD and the wiring VLS, and reliability can be improved. Further, for example, the off-state current can be decreased by supplying a potential that makes the threshold voltage of the transistor larger to the back gate. Thus, the current flowing through the wiring VLD from the wiring SIG and the current flowing through the wiring VLS from the wiring SIG can both be made extremely small during normal operation, and an increase in power consumption can be suppressed.

[0233] Thus, the semiconductor device of one embodiment of the present application can have various structures. Further, the semiconductor device can have structures appropriately combined, and is not limited to the above structures.

[0234] <Structure Example 2 of Semiconductor Device>

[0235] Next, a structure example in which the wiring SIG of the semiconductor device 100 is connected to the gate of another transistor is described. Thus, by using the semiconductor device 100 having the function of an ESD protection circuit, the transistor can be prevented from being damaged by a surge due to ESD or the like. Further, appropriate reference can be made to the above description, and thus the description thereof is sometimes omitted here.

[0236] Figure 11A is a top view illustrating a structure example in which the wiring SIG of the semiconductor device 100 is connected to the gate of the transistor 600e. Figure 11B is a cross-sectional view of the portion indicated by the dot-and-dash line A3-A4 in Figure 11A Note that, in the top view of Figure 11A , part of the components is omitted for clarity. Further, the cross-sectional view of the portion indicated by the dot-and-dash line Al-A2 in Figure 11A may be appropriately referred to Figure 1B .

[0237] In Figure 11A and Figure 11BIn this embodiment, as an example, the semiconductor device 100 and the transistor 600e are arranged in the Y direction.

[0238] In this embodiment, the transistor 600e corresponds to the transistor 600 described above. Thus, the conductor 630e corresponds to the conductor 630, the opening 648e corresponds to the opening 648, the oxide 650e corresponds to the oxide 650, and the conductor 660e corresponds to the conductor 660.

[0239] As shown in FIG. 6A, the conductor 670a which corresponds to the wiring SIG extends in the Y direction and includes a region serving as a gate electrode of the transistor 600a, a region serving as one of a source electrode and a drain electrode of the transistor 600b, and a region serving as a gate electrode of the transistor 600e. Further, the conductor 630e includes a region serving as one of a source electrode and a drain electrode of the transistor 600e. The conductor 660e includes a region serving as the other of the source electrode and the drain electrode of the transistor 600e. Figure 11A Figure 11B As shown in FIG. 6A, the conductor 670a which corresponds to the wiring SIG extends in the Y direction and includes a region serving as a gate electrode of the transistor 600a, a region serving as one of a source electrode and a drain electrode of the transistor 600b, and a region serving as a gate electrode of the transistor 600e. Further, the conductor 630e includes a region serving as one of a source electrode and a drain electrode of the transistor 600e. The conductor 660e includes a region serving as the other of the source electrode and the drain electrode of the transistor 600e.

[0240] In this embodiment, for example, when the transistor 600e is used for a storage device or the like, damage of the transistor 600e due to a surge generated by ESD or the like can be suppressed. Thus, the reliability of the storage device can be improved. At this time, the transistor 600a and the transistor 600e can be manufactured at the same time. Thus, the semiconductor device 100 can be provided without a large increase in process cost, and thus the reliability of the storage device can be improved.

[0241] Note that, for example, in the case where the transistor 600e is used for a storage device, the transistor can be used for a transistor included in a memory cell included in the storage device and a transistor included in a driver circuit for operating the storage device.

[0242] <Structure Example 3 of Semiconductor Device>

[0243] The transistor connected to the wiring SIG of the semiconductor device 100 is not limited to the structure example of the transistor 600e or the like described above.

[0244] Figure 12 is a cross-sectional view illustrating a structure example in which the wiring SIG of the semiconductor device 100 is connected to a gate of the transistor 500. In this embodiment, as an example, a structure example in which an upper layer of a layer in which the transistor 500 is provided is provided with a layer in which the semiconductor device 100 is provided is shown. Note that the above description can be referred to as appropriate, and thus the description thereof is omitted here in some cases. Figure 12

[0245] Figure 12 ​​The insulator 512, the transistor 500 over the insulator 512, the insulator 582 over the transistor 500, the insulator 584, the insulator 586, the insulator 588, the semiconductor device 100 over the insulator 588, and the like are shown.

[0246] The conductive body 614 and the conductive body 612 are embedded in the insulator 640a. The conductive body 610 is embedded in the insulator 620. The conductive body 548 is embedded in the insulator 588. The conductive body 546 is embedded in the insulator 586, the insulator 584, the insulator 582, and the like.

[0247] The conductive body 614, the conductive body 612, the conductive body 610, the conductive body 548, and the conductive body 546 each have a function of a plug or a wiring.

[0248] In this specification and the like, the same symbol is sometimes used to denote a plurality of conductive bodies each having a function of a plug or a wiring. Furthermore, a wiring and a plug can be one component. That is, part of a conductive body is sometimes used as a wiring, and another part of the conductive body is sometimes used as a plug.

[0249] As a material of each plug and wiring, for example, a single layer or a stack of a conductive material such as a metal material, an alloy material, a metal nitride material, or a metal oxide material can be used.

[0250] In particular, as each plug or wiring, a high-melting-point material having heat resistance and conductivity is preferably used. As such a material, for example, tungsten or molybdenum can be used. Furthermore, as each plug or wiring, a low-resistance conductive material capable of reducing wiring resistance is preferably used. As such a material, for example, aluminum or copper can be used.

[0251] The wiring SIG (corresponding to the conductive body 670a) is connected to a gate of the transistor 500 (corresponding to the conductive body 560 to be described later) through the conductive body 614, the conductive body 612, the conductive body 610, the conductive body 548, and the conductive body 546.

[0252] Here, the semiconductor device 100 can be provided over the transistor 500 in a manner overlapping with the transistor 500. Thus, for example, in the case where the transistor 500 is used for a storage device, the semiconductor device 100 can be provided in a manner that does not greatly increase the area cost of the storage device. Thus, the storage device can be reduced in size.

[0253] [Transistor 500]

[0254] The transistor 500 is described.

[0255] Figure 13A is a top view of the transistor 500. Figure 13B is a cross-sectional view taken along Figure 13AThe section shown by the dotted lines A1-A2 in the diagram is a cross-sectional view, which is also a cross-sectional view of the channel length direction (represented as the X direction) of transistor 500. Figure 13C It is along Figure 13A The cross-sectional view shown by the dashed lines A3-A4 is also a cross-sectional view of the channel width direction (represented as the Y direction) of transistor 500. Note that in Figure 13A In the top view, some constituent elements are omitted for clarity.

[0256] Transistor 500 is a so-called planar transistor, and compared to vertical transistors such as transistor 600 described above, its channel length can be increased more easily. Therefore, for example, it is easier to reduce short-channel effects such as drain-induced barrier lowering (DIBL). In other words, it is easier to achieve transistors with high saturation (small changes in drain current relative to drain voltage in the transistor's saturation region).

[0257] Therefore, for example, when transistor 500 is used in a storage device, it can also be used to form a transistor or the like that of a readout amplifier for reading data from the storage cells included in the storage device.

[0258] like Figure 13B and Figure 13C As shown, insulators 514 and 516 are stacked sequentially on insulator 512.

[0259] As any one of insulator 512, insulator 514 and insulator 516, an insulator that is resistant to oxygen, hydrogen and the like is preferred.

[0260] As the insulator 514, it is preferable to use a barrier insulator that can prevent impurities such as hydrogen from diffusing from the outside of the region where the transistor 500 is disposed into the region where the transistor 500 is disposed. As the insulator 514, for example, the same material as the insulator 324 described later can be used.

[0261] For example, metal oxides such as aluminum oxide, hafnium oxide, and tantalum oxide are preferred as insulators that block hydrogen.

[0262] In particular, aluminum oxide has a high barrier property against both impurities such as oxygen, hydrogen, and water. Therefore, during and after the transistor manufacturing process, aluminum oxide can prevent impurities such as hydrogen and water from entering the transistor 500, and can suppress the release of oxygen from the oxides constituting the transistor 500. Therefore, aluminum oxide is suitable for use as a protective film for the transistor 500.

[0263] The insulator 512 and the insulator 516 are formed using a material with low dielectric constant, so that parasitic capacitance generated between wirings can be reduced. For example, the same material as the insulator 326 to be described later can be used for the insulator 512 and the insulator 516.

[0264] As Figure 13B and Figure 13C illustrated, the transistor 500 includes the conductive body 503 configured to be embedded in the insulator 514 and the insulator 516, the insulator 522 configured over the insulator 516 and the conductive body 503, the insulator 524 configured over the insulator 522, the oxide 530a configured over the insulator 524, the oxide 530b configured over the oxide 530a, the conductive body 542a and the conductive body 542b configured over the oxide 530b so as to be separated from each other, the insulator 580 configured over the conductive body 542a and the conductive body 542b and formed with an opening overlapping between the conductive body 542a and the conductive body 542b, the insulator 545 configured along the opening, and the conductive body 560 configured over a surface of the insulator 545.

[0265] Note that the oxide 530a and the oxide 530b are collectively referred to as an oxide 530 in some cases.

[0266] The oxide 530 has a function of a semiconductor film including a channel formation region of the transistor 500.

[0267] The conductive body 503 is configured to overlap with the oxide 530 and the conductive body 560.

[0268] Here, the conductive body 503 preferably includes the conductive body 503a provided to be in contact with the insulator 514 and the insulator 516, and the conductive body 503b provided to be embedded in an inner side of the conductive body 503a. Further, the insulator 544 is preferably provided between the oxide 530a, the oxide 530b, the conductive body 542a, and the conductive body 542b and the insulator 580. Further, the conductive body 560 preferably includes the conductive body 560a provided in an inner side of the insulator 545, and the conductive body 560b provided to be embedded in an inner side of the conductive body 560a. Further, the insulator 582 is preferably provided over the insulator 580, the conductive body 560, and the insulator 545.

[0269] Note that in the transistor 500 illustrated in FIGS. 6A and 6B, two layers of the conductive body 503a and the conductive body 503b are stacked over the conductive body 503, but the structure is not limited thereto. For example, a single-layer structure or a stacked structure of three or more layers can be employed. Figure 13B Figure 13C Note that in the transistor 500 illustrated in FIGS. 6A and 6B, two layers of the conductive body 503a and the conductive body 503b are stacked over the conductive body 503, but the structure is not limited thereto. For example, a single-layer structure or a stacked structure of three or more layers can be employed.

[0270] ​Further, a structure in which the end portions of the conductors 542a and 542b coincide with the end portion of the oxide 530 is shown, but the present application is not limited to this. For example, the conductors 542a and 542b can be made to extend beyond the end portion of the oxide 530.

[0271] Further, a two-layer stacked structure in which the oxide 530 has an oxide 530a and an oxide 530b is shown, but the present application is not limited to this. For example, a single-layer structure or a stacked structure of three or more layers can also be employed.

[0272] Further, a structure in which the conductors 560a and 560b are stacked in two layers is shown as the conductors 560, but the present application is not limited to this. For example, a single-layer structure or a stacked structure of three or more layers can also be employed.

[0273] Here, in the transistor 500, the conductor 560 has the function of a gate electrode, the insulator 545 has the function of a gate insulating film, and the conductors 542a and 542b have the functions of one of a source electrode and a drain electrode and the other thereof.

[0274] As described above, the conductor 560 is formed so as to be embedded in the opening of the insulator 580 formed in the region sandwiched between the conductors 542a and 542b (sometimes referred to as the opening of the insulator 580). Thus, the arrangement of the conductor 560, the conductors 542a and 542b, and the opening of the insulator 580 is self-aligned. That is, in the transistor 500, the gate electrode can be arranged between the source electrode and the drain electrode self-aligned. By employing such a structure, the conductor 560 can be formed without providing a margin for alignment. Thus, reduction in the area occupied by the transistor 500 can be achieved. Thus, miniaturization or high integration of the semiconductor device can be achieved.

[0275] Further, the conductor 560 is formed self-aligned in the region between the conductors 542a and 542b, and thus the conductor 560 does not include a region overlapping with the conductor 542a or the conductor 542b. Thus, the parasitic capacitance formed between the conductor 560 and the conductors 542a and 542b can be reduced. Thus, the switching speed of the transistor 500 can be increased. Thus, the frequency characteristics of the semiconductor device can be improved.

[0276] Further, when miniaturization of the semiconductor device is performed, the gate length of the transistor 500 needs to be shortened, but at this time, the decrease in the conductivity of the conductor 560 needs to be prevented. For this reason, in the case where the thickness of the conductor 560 is increased, the conductor 560 can have a shape with a high aspect ratio. Thus, by providing the conductor 560 so as to be embedded in the opening of the insulator 580, the conductor 560 with a high aspect ratio can be formed without collapse in the process.

[0277] Here, the conductive body 560 has a function of a first gate electrode, and the conductive body 503 has a function of a second gate electrode. In this case, the insulator 545 has a function of a first gate insulating film, and the insulator 522 and the insulator 524 have a function of a second gate insulating film.

[0278] As described above, the conductive body 503 is arranged so as to overlap with the oxide 530 and the conductive body 560. Thus, in the case where an electric potential is supplied to the conductive body 560 and the conductive body 503, an electric field generated from the conductive body 560 and an electric field generated from the conductive body 503 are connected, and a channel formation region formed in the oxide 530 can be covered.

[0279] In this case, in the transistor 500, by independently changing the electric potential supplied to the conductive body 503 from the electric potential supplied to the conductive body 560, the threshold voltage of the transistor 500 can be controlled. In particular, by supplying a negative electric potential to the conductive body 503, the threshold voltage of the transistor 500 can be increased and the off-state current can be reduced. Thus, for example, by supplying a negative electric potential to the conductive body 503, the drain current at the time when the electric potential supplied to the conductive body 560 is 0 V (which is sometimes referred to as off current) can be reduced.

[0280] Note that in this specification and the like, a structure of a transistor in which a channel is surrounded by electric fields of gate electrodes is referred to as a surrounded channel (S-channel) structure. Further, it can be said that the S-channel structure disclosed in this specification and the like is different from a Fin structure and a planar structure. On the other hand, the S-channel structure disclosed in this specification and the like can be regarded as one of the Fin structure and the planar structure. Further, in this specification and the like, the Fin structure refers to a structure in which a gate electrode is arranged so as to surround at least two surfaces (specifically, two surfaces, three surfaces, or four surfaces, or the like) of a channel. By employing the Fin structure and the S-channel structure, a transistor with high resistance to short channel effects can be realized. In other words, a transistor in which short channel effects are less likely to occur can be realized.

[0281] By employing a transistor having the above S-channel structure, the channel formation region can be electrically surrounded by the electric field of the gate electrode. Since the S-channel structure is a structure in which the channel formation region is electrically surrounded by the electric field of the gate electrode, it can be said that the structure is substantially the same as a GAA (Gate All Around) structure or an LGAA (Lateral Gate All Around) structure. By making the transistor have the S-channel structure, the GAA structure, or the LGAA structure, the channel formation region formed at or near the interface between the semiconductor film and the gate insulating film can be provided in the entire bulk of the semiconductor film. Thus, the current density flowing through the transistor can be increased, so that an increase in on-state current of the transistor or an increase in field-effect mobility of the transistor can be achieved.

[0282] As described above, in the conductor 503, the conductor 503a is formed in contact with the insulator 514 and the insulator 516, and the conductor 503b is formed inside the conductor 503a.

[0283] As the conductor 503a, for example, a conductive material having barrier properties (having a function of suppressing diffusion of impurities such as hydrogen (e.g., at least one of a hydrogen atom and a hydrogen molecule), water, and copper) is preferably used. Further, as the conductor 503a, for example, a conductive material having barrier properties (having a function of suppressing diffusion of oxygen (e.g., at least one of an oxygen atom and an oxygen molecule)) is preferably used. In other words, the conductor 503a preferably has barrier properties with respect to one or all of the above impurities and the above oxygen.

[0284] For example, by making the conductor 503a have barrier properties with respect to oxygen, a decrease in conductivity due to oxidation of the conductor 503b can be suppressed. Thus, the conductor 503 can also have a function of a wiring.

[0285] At this time, as the conductor 503b, a conductive material with high conductivity is preferably used. For example, a conductive material in which tungsten, copper, or aluminum is a main component can be used.

[0286] Further, the transistor 500 can not include the conductor 503 (i.e., can not include a back gate).

[0287] Here, the insulator in contact with the oxide 530 preferably uses an insulator containing oxygen exceeding the stoichiometric composition. The oxygen is easily released from the insulator by heating. In this specification and the like, the oxygen released by heating is sometimes referred to as "excess oxygen".

[0288] The insulator 524 is in contact with the oxide 530. Thus, a region containing excess oxygen (also referred to as an "excess oxygen region") is preferably formed in the insulator 524.

[0289] By providing an insulator containing excess oxygen in contact with oxide 530, the oxygen vacancies (V) in oxide 530 can be reduced. O (oxygen vacancy), which can improve the reliability of transistor 500.

[0290] Here, an oxide semiconductor that can be used with oxide 530 is described. This oxide semiconductor contains a metal oxide.

[0291] Furthermore, it is preferable to minimize the amount of hydrogen in the oxide semiconductor. Hydrogen in oxide semiconductors bonds with oxygen vacancies, forming defects (also known as V0) where hydrogen enters oxygen vacancies. O Therefore, transistor characteristics (e.g., the initial Id-Vg characteristic of the transistor or the Id-Vg characteristic in long-term reliability testing) may deteriorate. As the material surrounding the oxide semiconductor, such as the material used as an insulator in contact with the oxide semiconductor, a material with low hydrogen release is preferred. Examples of materials with low hydrogen release include silicon nitride, silicon oxynitride, aluminum oxide, and hafnium oxide. This suppresses hydrogen incorporation into the oxide semiconductor. In particular, when silicon nitride is used in at least one of the insulators in contact with the oxide semiconductor, transistor reliability can be improved. Note that materials with low hydrogen release sometimes have the function of trapping or fixing hydrogen inside the insulator (also known as gettering).

[0292] Furthermore, in oxide 530, sometimes V O H is used as a donor to generate electrons as charge carriers. Furthermore, sometimes electrons are generated as charge carriers due to partial bonding of hydrogen with oxygen atoms bonded to metal atoms. Therefore, transistors using oxide semiconductors containing a large amount of hydrogen tend to have always-on characteristics. However, because hydrogen in oxide semiconductors is easily transferred due to heat, electric fields, etc., a large amount of hydrogen in the oxide semiconductor may lead to a decrease in transistor reliability. In one aspect of the invention, it is preferable to minimize V0 in the oxide 530. O H thus becomes a high-purity intrinsic or substantially high-purity intrinsic.

[0293] Thus, in order to obtain V O For oxide semiconductors where H is sufficiently reduced, it is important to: remove impurities such as hydrogen and water from the oxide semiconductor (sometimes referred to as "dehydration" or "dehydrogenation treatment"); and supply oxygen to the oxide semiconductor to fill oxygen vacancies (sometimes referred to as "oxidation treatment"). By increasing V... O Oxide semiconductors with sufficiently reduced impurities such as hydrogen (H) can impart stable electrical characteristics when used in the channel formation region of transistors.

[0294] When the insulator 524 includes an excess-oxygen region, the insulator 522 is preferably oxygen-blocking. When the insulator 522 is oxygen-blocking, diffusion of oxygen included in the oxide 530 to the side of the insulator 516, for example, can be suppressed. Further, reaction of the conductive object 503 with oxygen included in the insulator 524 or the oxide 530, or the like can be suppressed.

[0295] Here, in a transistor whose channel formation region is formed using an oxide semiconductor, it is preferable that the number of oxygen vacancies or the impurity concentration (e.g., the concentration of hydrogen, nitrogen, a metal element, or the like) be lower than that in a source region and a drain region. Further, in some cases, hydrogen in the vicinity of an oxygen vacancy forms V O Hand generates an electron which becomes a carrier, and thus V O His also preferable to be small. In that case, the channel formation region of the transistor is a high-resistance region in which the carrier concentration is low. Thus, the channel formation region of the transistor can be said to be i-type (intrinsic) or substantially i-type.

[0296] Further, the source region and the drain region are preferably higher in the number of oxygen vacancies, V O H, or higher in the impurity concentration than the channel formation region of the transistor. In that case, the source region and the drain region are n-type regions which are higher in carrier concentration and lower in resistance than the channel formation region of the transistor.

[0297] The metal oxide used as the oxide semiconductor is preferably greater than or equal to 2 eV, further preferably greater than or equal to 2.5 eV in a band gap. By using a metal oxide with a large band gap as the oxide semiconductor, the off-state current of the transistor can be reduced.

[0298] As the insulator 522, an insulator formed of a high-k material (a material with a high relative dielectric constant) is preferably used.

[0299] With miniaturization and high integration of transistors, problems such as gate current might occur due to thinning of a gate insulating film. By using a high-k material as the insulator used as the gate insulating film, the gate potential at the time of transistor operation can be reduced while the physical thickness is maintained.

[0300] As the insulator used as the gate insulating film, a single layer or a stack of insulators containing aluminum oxide, hafnium oxide, an oxide containing aluminum and hafnium (hafnium aluminate), tantalum oxide, zirconium oxide, lead zirconate titanate (PZT), strontium titanate (SrTiO3), barium strontium titanate (BST), or the like is preferably used, for example.

[0301] In particular, as an insulator which is oxygen-blocking and impurity-blocking, an insulator containing an oxide of one or both of aluminum and hafnium is preferably used. As the insulator, aluminum oxide, hafnium oxide, an oxide containing aluminum and hafnium (hafnium aluminate), or the like is preferably used, for example.

[0302] In addition, aluminum oxide, bismuth oxide, germanium oxide, niobium oxide, silicon oxide, titanium oxide, tungsten oxide, yttrium oxide, or zirconium oxide can be added to the insulator. Alternatively, the insulator can be nitrided. Furthermore, silicon oxide, silicon oxynitride, or silicon nitride can be laminated onto the insulator.

[0303] When this material is used to form insulator 522, insulator 522 can be used as an insulator to suppress the release of oxygen from oxide 530 and the entry of impurities such as hydrogen from the periphery of transistor 500 into oxide 530.

[0304] Note that in Figure 13B and Figure 13C In the transistor 500 shown, two layers of insulator 522 and insulator 524 are stacked as the second gate insulating film, but the transistor is not limited to this. For example, it may have a single-layer structure or a stacked structure of three or more layers. In this case, a structure of stacked materials of the same material or different materials may be used.

[0305] In transistor 500, a metal oxide used as an oxide semiconductor is used as oxide 530, which includes the channel formation region. For example, a metal oxide that can be used for oxide 650 described above can also be used as oxide 530. Note that a single layer or a stack of metal oxides can be used as the oxide semiconductor.

[0306] In oxide 530, when oxide 530a is disposed below oxide 530b, impurities can be suppressed from diffusing from the structure formed below oxide 530a to oxide 530b.

[0307] Furthermore, oxide 530 preferably has a structure comprising multiple oxide layers in which the atomic ratios of each metal atom are different. Specifically, the atomic ratio of element M in the metal oxide of oxide 530a is preferably greater than that in the metal oxide of oxide 530b. Furthermore, the atomic ratio of element M relative to In in the metal oxide of oxide 530a is preferably greater than that in the metal oxide of oxide 530b. Furthermore, the atomic ratio of In relative to element M in the metal oxide of oxide 530b is preferably greater than that in the metal oxide of oxide 530a.

[0308] Preferably, the energy of the conduction band bottom of oxide 530a is higher than that of oxide 530b. In other words, the electron affinity of oxide 530a is preferably less than that of oxide 530b.

[0309] Here, in the junction of the oxide 530a and the oxide 530b, the energy level of the conduction band bottom gently changes. In other words, the above case can also be expressed as the energy level of the conduction band bottom of the junction of the oxide 530a and the oxide 530b continuously changes or continuously joins. For this reason, the defect state density of the mixed layer formed at the interface of the oxide 530a and the oxide 530b can be reduced.

[0310] Specifically, by making the oxide 530a and the oxide 530b contain a common element (as a main component) in addition to oxygen, a mixed layer with a low defect state density can be formed. For example, in the case where the oxide 530b is an In-Ga-Zn oxide, as the oxide 530a, an In-Ga-Zn oxide, a Ga-Zn oxide, a gallium oxide, or the like can be used.

[0311] At this time, the main path of the carriers is the oxide 530b. By making the oxide 530a have the above structure, the defect state density at the interface of the oxide 530a and the oxide 530b can be reduced. Thus, the influence of the interface scattering on the carrier conduction is reduced, and the on-state current of the transistor 500 can be increased.

[0312] The oxide 530b is provided with a conductor 542a and a conductor 542b serving as a source electrode and a drain electrode.

[0313] As the conductor 542a and the conductor 542b, for example, a metal element selected from aluminum, chromium, copper, silver, gold, platinum, tantalum, nickel, titanium, molybdenum, tungsten, hafnium, vanadium, niobium, manganese, magnesium, zirconium, beryllium, indium, ruthenium, iridium, strontium, and lanthanum, an alloy containing the above metal element, or an alloy in which the above metal elements are combined, or the like can be used. In particular, from the viewpoint of a conductive material which is not easily oxidized or a material which maintains its conductivity even if oxygen is absorbed, it is preferable to use tantalum nitride, titanium nitride, a nitride containing titanium and aluminum, a nitride containing tantalum and aluminum, ruthenium oxide, ruthenium nitride, an oxide containing strontium and ruthenium, an oxide containing lanthanum and nickel, or the like. Furthermore, from the viewpoint of a barrier property against oxygen, hydrogen, and the like, for example, it is preferable to use a metal nitride film such as tantalum nitride.

[0314] Note that, in the transistor 500 illustrated in FIGS. 1A to 1C, the conductor 542a and the conductor 542b have a single-layer structure, but they are not limited to this structure. For example, the conductor 542a and the conductor 542b can have a stacked-layer structure of two or more layers. Figure 13B Figure 13C Note that, in the transistor 500 illustrated in FIGS. 1A to 1C, the conductor 542a and the conductor 542b have a single-layer structure, but they are not limited to this structure. For example, the conductor 542a and the conductor 542b can have a stacked-layer structure of two or more layers.

[0315] As the conductor 542a and the conductor 542b, for example, a stacked-layer structure of a tantalum nitride film and a tungsten film, a stacked-layer structure of a titanium film and an aluminum film, a structure in which an aluminum film is stacked over a tungsten film, a structure in which a copper film is stacked over a copper-magnesium-aluminum alloy film, a structure in which a copper film is stacked over a titanium film, or a structure in which a copper film is stacked over a tungsten film can be used.​

[0316] Further, for example, a three-layer structure in which an aluminum film or a copper film is stacked on a titanium film or a titanium nitride film and a titanium film or a titanium nitride film is stacked thereon, or a three-layer structure in which an aluminum film or a copper film is stacked on a molybdenum film or a molybdenum nitride film and a molybdenum film or a molybdenum nitride film is stacked thereon, or the like can be employed.

[0317] Further, the conductive body 542a and the conductive body 542b can also use a transparent conductive material including indium oxide, tin oxide, or zinc oxide.

[0318] Further, as shown in FIG. 5B, a region 543a is sometimes formed as a low-resistance region at the interface between the oxide 530 and the conductive body 542a and in the vicinity thereof. Similarly, a region 543b is sometimes formed as a low-resistance region at the interface between the oxide 530 and the conductive body 542b and in the vicinity thereof. At this time, the region 543a is used as one of the source region and the drain region, and the region 543b is used as the other of the source region and the drain region. Further, a channel formation region is formed in a region sandwiched between the region 543a and the region 543b. Figure 13B

[0319] Thus, by providing the conductive body 542a and the conductive body 542b in contact with the oxide 530, the oxygen concentration of the region 543a and the region 543b is sometimes reduced. Further, a metal compound layer including a component of the metal in the conductive body 542a and the conductive body 542b and the oxide 530 is sometimes formed in the region 543a and the region 543b. In this case, the carrier concentration of the region 543a and the region 543b is increased, and the region 543a and the region 543b become low-resistance regions.

[0320] The insulator 544 is provided so as to cover the conductive body 542a and the conductive body 542b, and oxidation of the conductive body 542a and the conductive body 542b is suppressed. At this time, the insulator 544 can also be provided so as to cover the side surfaces of the oxide 530 and the insulator 524 respectively and be in contact with the insulator 522.

[0321] As the insulator 544, a metal oxide including one or two or more selected from hafnium, aluminum, gallium, yttrium, zirconium, tungsten, titanium, tantalum, nickel, germanium, neodymium, lanthanum, or magnesium, or the like can be used. Further, for example, silicon oxynitride or silicon nitride, or the like can be used.

[0322] Further, an insulator including an oxide of one or both of aluminum and hafnium can also be used. For example, aluminum oxide, hafnium oxide, an oxide including aluminum and hafnium (hafnium aluminate), or the like can be used. In particular, from the point of view that the heat resistance is high and crystallization is less likely to occur in heat treatment in a later step, for example, hafnium aluminate is preferably used.

[0323] ​Furthermore, if conductors 542a and 542b are made of materials that are resistant to oxidation or materials whose conductivity does not decrease significantly when absorbing oxygen, it is not necessarily necessary to provide insulator 544.

[0324] Furthermore, by including insulator 544, the diffusion of impurities such as hydrogen and water contained in insulator 580 to oxide 530b can be suppressed. Additionally, the oxidation of conductors 542a and 542b by excess oxygen contained in insulator 580 can be suppressed.

[0325] As the insulator 545, it is preferable to use an insulator containing excess oxygen and releasing oxygen by heating, similar to the insulator 524 described above. Therefore, oxygen can be effectively supplied from the insulator 545 to the channel forming region of the oxide 530b.

[0326] Specifically, as the insulator 545, silicon oxide with excess oxygen, silicon oxynitride, silicon oxynitride, silicon nitride, silicon oxide with added fluorine, silicon oxide with added carbon, silicon oxide with added carbon and nitrogen, and silicon oxide with pores can be used. In particular, from the viewpoint of thermal stability, silicon oxide or silicon oxynitride is preferred.

[0327] Furthermore, similar to the insulator 524 described above, the insulator 545 preferably uses an insulator with reduced concentrations of impurities such as hydrogen and water. The thickness of the insulator 545 is preferably 1 nm or more and 20 nm or less.

[0328] To efficiently supply excess oxygen contained in the insulator 545 to the oxide 530, a metal oxide may be disposed between the insulator 545 and the conductor 560. This metal oxide preferably has oxygen-blocking properties. This suppresses the diffusion of excess oxygen from the insulator 545 to the conductor 560. Therefore, the reduction of excess oxygen supplied to the oxide 530 can be suppressed. Furthermore, oxidation of the conductor 560 due to excess oxygen can be suppressed. As this metal oxide, a material suitable for the insulator 544 can also be used.

[0329] exist Figure 13B and Figure 13C In the transistor 500 shown, the insulator 545 has a single-layer structure, but is not limited to this. For example, similar to the insulators 522 and 524 used as the second gate insulating film, the insulator 545 used as the first gate insulating film can also have a stacked structure of two or more layers. For example, the insulator 545 can also have a stacked structure of a high-k material and a thermally stable material. Thus, the gate voltage of the transistor 500 during operation can be reduced while maintaining the physical thickness of the insulator 545.

[0330] As the conductive body 560a included in the conductive body 560, for example, a conductive material having barrier properties against hydrogen, water, nitrogen, nitrogen oxide (e.g., N20, NO, or NO2, or the like), and copper or the like impurities is preferably used. Further, a conductive material having barrier properties against oxygen is preferably used. When the conductive body 560a has barrier properties against oxygen, oxygen contained in the insulator 545 can be prevented from oxidizing the conductive body 560b, which can cause a decrease in conductivity.

[0331] As the conductive material having barrier properties against oxygen, for example, tantalum, tantalum nitride, ruthenium, or ruthenium oxide, or the like is preferably used.

[0332] Further, as the conductive body 560a, an oxide semiconductor applicable to the oxide 530 can be used. In that case, by depositing the conductive body 560b by a sputtering method, the resistance value of the conductive body 560a can be reduced to make it a conductor. This can be referred to as an OC (Oxide Conductor) electrode.

[0333] The conductive body 560 can also have a function of a wiring. Thus, as the conductive body 560b, a conductive material having high conductivity is preferably used, like the conductive body 503b. For example, a conductive material in which tungsten, copper, or aluminum is a main component can be used.

[0334] Further, the conductive body 560b can also have a structure in which different materials are stacked. For example, a stacked structure of titanium or titanium nitride and the conductive material described above can be included.

[0335] The insulator 580 is preferably provided over the conductive body 542a and the conductive body 542b with the insulator 544 interposed therebetween.

[0336] The insulator 580 preferably includes an excess-oxygen region.

[0337] As the insulator 580, for example, silicon oxide, silicon oxynitride, silicon nitride oxide, silicon nitride, silicon oxide to which fluorine is added, silicon oxide to which carbon is added, silicon oxide to which carbon and nitrogen are added, silicon oxide having a void, or a resin, or the like can be used. In particular, from the viewpoint of heat stability, silicon oxide or silicon oxynitride is preferably used. Further, from the viewpoint of easily forming an excess-oxygen region in a later step, silicon oxide or silicon oxide having a void is preferably used.

[0338] By providing the insulator 580 including an excess-oxygen region, oxygen can be released by heating, and thus oxygen in the insulator 580 can be efficiently supplied to the oxide 530. Further, it is preferable to reduce the concentration of impurities such as hydrogen and water in the insulator 580.

[0339] The insulator 582 is preferably provided in contact with the top surface of the insulator 580, the top surface of the electrically conductive body 560, and the top surface of the insulator 545. By depositing the insulator 582 using a sputtering method, an excess-oxygen region can be formed in the insulator 545 and the insulator 580. Thereby, oxygen can be supplied from the excess-oxygen region to the oxide 530.

[0340] As the insulator 582, for example, a metal oxide containing one or two or more selected from hafnium, aluminum, gallium, yttrium, zirconium, tungsten, titanium, tantalum, nickel, germanium, and magnesium, or the like can be used.

[0341] In particular, aluminum oxide has high barrier properties against impurities such as hydrogen, and even a thin film of 0.5 nm or more and 3.0 nm or less can suppress diffusion of impurities such as hydrogen. Thereby, aluminum oxide deposited using a sputtering method can have a function of an insulator having barrier properties against impurities such as hydrogen in addition to a function of an oxygen supply source.

[0342] An insulator 584 serving as an interlayer film is preferably provided on the insulator 582. As with the insulator 524, it is preferable to reduce the concentration of impurities such as hydrogen and water in the insulator 584.

[0343] Further, the electrically conductive bodies 540a and 540b are provided in openings formed in the insulator 584, the insulator 582, the insulator 580, and the insulator 544. At this time, the electrically conductive bodies 540a and 540b are provided in opposition to each other with the electrically conductive body 560 interposed therebetween. The electrically conductive bodies 540a and 540b have the same structure as the electrically conductive body 546 described later.

[0344] The insulator 584 is provided with an insulator 586.

[0345] As the insulator 586, an insulating material having barrier properties against oxygen and impurities such as hydrogen is preferably used. As the insulator 586, for example, the same material as the insulator 514 or the like can be used.

[0346] The insulator 586 is provided with an insulator 588.

[0347] By using, for example, a material having a low dielectric constant as the insulator 588, parasitic capacitance generated between wirings can be reduced. As the insulator 588, for example, the same material as the insulator 512 or the insulator 516 or the like can be used.

[0348] For example, the electrically conductive body 546 or the like is embedded in the insulator 580, the insulator 582, the insulator 584, and the insulator 586. Further, for example, the electrically conductive body 548 or the like is embedded in the insulator 588.

[0349] The electrically conductive bodies 546 and 548 both have the function of a plug or a wiring.

[0350] Further, after the transistor 500 is formed, an opening can be formed so as to surround the transistor 500, and an insulator having a high barrier property against hydrogen or water can be formed so as to cover the opening. By wrapping the transistor 500 with the insulator having a high barrier property as described above, entry of hydrogen and water from the outside can be prevented. Alternatively, a plurality of transistors 500 can be wrapped with the insulator having a high barrier property against hydrogen or water. Further, in the case where the opening is formed so as to surround the transistor 500, for example, the insulator having a high barrier property as described above can be formed so as to reach the insulator 522 or the insulator 514 and be in contact with the insulator 522 or the insulator 514. Thus, the insulator can serve as part of the manufacturing process of the transistor 500. Further, as the insulator having a high barrier property against hydrogen or water, a material similar to the insulator 522 or the insulator 514 can be used, for example.

[0351] Note that, Figures 13A to 13C The transistor 500 illustrated in FIGS. 1A and 1B is just an example and not limited to the above structure.

[0352] [Transistor 500F]

[0353] A structure example of a transistor having a different structure from the transistor 500 is described with reference to FIGS. 14 to 18. Figure 14A is a top view of the transistor 500F. Figure 14B is a schematic cross-sectional view of the transistor 500F. Note that, Figures 14C to 14E is a cross-sectional view of the transistor 500F. Here, Figure 14C is a cross-sectional view of a portion indicated by a dot-and-dash line A1-A2 in Figure 14A , and is also a cross-sectional view in a channel width direction (here, denoted as a Y direction) of the transistor 500F. Figure 14D is a cross-sectional view of a portion indicated by a dot-and-dash line A3-A4 in Figure 14A , and is also a cross-sectional view in the channel width direction of the transistor 500F. Note that, Figure 14E is a cross-sectional view of a portion indicated by a dot-and-dash line A5-A6 in Figure 14A , and is also a cross-sectional view in a channel length direction (here, denoted as an X direction) of the transistor 500F. Here, the dot-and-dash line A5-A6 is orthogonal to the dot-and-dash line A1-A2 and the dot-and-dash line A3-A4, and the dot-and-dash line A1-A2 and the dot-and-dash line A3-A4 are parallel to each other. Note that, in the top view of Figure 14A and the schematic cross-sectional view of Figure 14B , the description of part of the components is omitted. Note that, Figure 15A is an enlarged view of the vicinity of the conductive body 560 in Figure 14E . Note that, Figure 15B is an enlarged view of the vicinity of the oxide 530 in Figure 14C .

[0354] The transistor 500F has a structure in which the channel width can be increased without a large increase in the area occupancy, compared with the transistor 500. That is, the on-state current can be increased without a large increase in the area occupancy.

[0355] Accordingly, for example, by using the transistor 500F for a memory device, the operation speed of the memory device, such as the read and write speeds of data of memory cells included in the memory device, can be increased.

[0356] The transistor 500F includes the insulator 514 over a substrate (not illustrated), the insulator 516 over the insulator 514, the insulator 521 over the insulator 516, the insulator 522 over the insulator 521, the oxide 530 over the insulator 522, the conductors 542a and 542b over the oxide 530 and the insulator 522, the insulator 545 over the oxide 530, and the conductor 560 (the conductor 560a and the conductor 560b) over the insulator 545. Note that in this specification and the like, the conductors 542a and 542b are collectively referred to as the conductor 542 in some cases.

[0357] The insulator 544 is provided over the conductor 542, and the insulator 580 is provided over the insulator 544. The insulator 545 and the conductor 560 are provided inside a first opening portion reaching the oxide 530 through the insulator 580 and the insulator 544. The first opening portion includes, in plan view, a region overlapping with the oxide 530 and a region extending along the channel width direction beyond the end portion of the oxide 530. Thus, the insulator 545 and the conductor 560 provided inside the first opening portion also include, in plan view, a region overlapping with the oxide 530 and a region extending along the channel width direction beyond the end portion of the oxide 530. The conductor 560 also functions as a wiring. The insulator 545 includes a region in contact with the oxide 530 in the first opening portion. Further, the insulator 582 is provided over the insulator 580 and the conductor 560. Further, the insulator 584 is provided over the insulator 582.

[0358] Further, the insulator 541a is provided in contact with the side surface of a second opening portion reaching the conductor 542a through the insulator 584, the insulator 582, the insulator 580, and the insulator 544, and the conductor 540a is provided in contact with the insulator 541a. The conductor 540a includes a region in contact with the conductor 542a at the bottom of the first opening portion.

[0359] Furthermore, an insulator 541b is provided in such a way that it contacts the side of the third opening that passes through insulators 584, 582, 580, and 544 to reach conductor 542b, and a conductor 540b is provided in such a way that it contacts insulator 541b. Conductor 540b includes a region at the bottom of the second opening that contacts conductor 542b.

[0360] In this specification and other materials, conductor 540a and conductor 540b are sometimes collectively referred to as conductor 540. Additionally, insulator 541a and insulator 541b are sometimes collectively referred to as insulator 541.

[0361] Oxide 530 includes the channel forming region of transistor 500F. Conductor 560 includes a region serving as the gate electrode of transistor 500F. Insulator 545 includes a region serving as the gate insulating film of transistor 500F. In transistor 500F, the region of oxide 530 overlapping with conductor 560 is used as the channel forming region. Furthermore, the region of conductor 560 overlapping with oxide 530 is used as the gate electrode. Additionally, the region of insulator 545 overlapping with oxide 530 and conductor 560 is used as the gate insulating film.

[0362] Conductor 542a includes a region that serves as one of the source and drain electrodes of transistor 500F. Conductor 540a is used as a connector to conductor 542a. Conductor 542b includes a region that serves as the other of the source and drain electrodes of transistor 500F. Conductor 540b is used as a connector to conductor 542b.

[0363] Oxide 530 is formed on insulator 522. For example... Figure 15B As shown, oxide 530 has a high aspect ratio shape when viewed in cross-section along the channel width direction. Therefore, it can be said that oxide 530 has a fin-like shape.

[0364] In this specification, the maximum length of the oxide 530 in the channel width direction within the channel forming region is defined as length Lx, and the maximum length of the oxide 530 in the channel forming region in the direction perpendicular to the formed surface (e.g., the top surface of the insulator 522) (here, the Z direction) is defined as length H. The ratio of length H to length Lx is referred to as the aspect ratio of the oxide 530. Furthermore, fin-shaped refers to a shape in which the oxide 530 has a high aspect ratio when viewed in cross-section along the channel width direction (a shape where length H is large relative to length Lx). Here, transistors in which the semiconductor layer including the channel forming region is fin-shaped are sometimes referred to as fin transistors, Fin-type transistors, Fin transistors, etc.

[0365] Note that the length Lx can also be described as the maximum width of the oxide 530 in the channel formation region. Therefore, "length Lx" can be replaced with "width Lx". Furthermore, the length H can also be described as the maximum height of the oxide 530 in the channel formation region. Therefore, "length H" can be replaced with "height H".

[0366] The aspect ratio of oxide 530 is preferably as high as possible within a range that will not cause oxide 530 to collapse during the manufacturing process of transistor 500F. The aspect ratio of oxide 530 may also be greater than 1 and less than 400, preferably greater than 2 and less than 100, more preferably greater than 5 and less than 40, and even more preferably greater than 10 and less than 20. That is, in the channel formation region of oxide 530, the height H of oxide 530 is preferably at least longer than the length Lx of oxide 530. The height H of oxide 530 may also be greater than 1 times and less than 400 times the length Lx of oxide 530, preferably greater than 2 times and less than 100 times, more preferably greater than 5 times and less than 40 times, and even more preferably greater than 10 times and less than 20 times. Furthermore, for example, the height H may also be greater than 2 times and less than 10 times the length Lx. For example, the length Lx may also be greater than 5 nm and less than 100 nm, preferably greater than 5 nm and less than 50 nm, and even more preferably greater than 10 nm and less than 30 nm. Furthermore, for example, the height H can be 50 nm or more and 2000 nm or less, preferably 100 nm or more and 1000 nm or less. Furthermore, for example, the height H can be 50 nm or more and 100 nm or less.

[0367] In addition, such as Figure 15B As shown, when viewed in a cross-section along the channel width direction, the angle θ formed by the forming surface of the oxide 530 on the insulator 522 and the side surface of the oxide 530 is preferably perpendicular. For example, the angle θ is 80° or more and 100° or less, preferably 85° or more and 95° or less.

[0368] The insulator 545, conductor 560, and conductor 542 are disposed in a manner that covers the oxide 530 with a high aspect ratio. In transistor 500F, as... Figure 15B As shown, the insulator 545 and a portion of the conductor 560 are arranged in a folded manner, sandwiching the oxide 530. Thus, when viewed in cross-section along the channel width direction, the oxide 530 and conductor 560 are positioned opposite each other, sandwiching the insulator 545 between the upper part of the oxide 530, the side surface on the A1 side, and the side surface on the A2 side. In other words, the upper part of the oxide 530, the side surface on the A1 side, and the side surface on the A2 side are all used as channel forming regions. Therefore, compared to the case where the oxide 530 is formed as a planar shape, the channel width of the transistor 500F is increased by the size of the side surfaces on the A1 and A2 sides of the oxide 530.

[0369] As described above, by making the channel width large, the on-state current, the transconductance, the frequency characteristics, and the like of the transistor 500F can be increased. Thus, a semiconductor device with high operation speed can be provided. Further, in the structure of the transistor 500F, the channel width can be increased without increasing the area occupied when the oxide 530 is provided. Thus, miniaturization or high integration of the semiconductor device can be achieved.

[0370] Further, as described in Patent Document 1, Patent Document 2, and the like, the upper portion of the oxide 530 can also have a curved shape. By having such a curved shape, formation of defects such as voids in the insulator 545 and the conductor 542 near the upper portion of the oxide 530 can be prevented. Note that although a structure in which both the Al side and the A2 side of the upper portion of the oxide 530 have a curved shape is employed in Patent Document 1 and Patent Document 2, one embodiment of the present application is not limited to this. For example, a structure in which one of the Al side and the A2 side of the upper portion of the oxide 530 has a curved shape is sometimes employed. Figure 15B Figure 15B Further, as described in Patent Document 1, Patent Document 2, and the like, the upper portion of the oxide 530 can also have a curved shape. By having such a curved shape, formation of defects such as voids in the insulator 545 and the conductor 542 near the upper portion of the oxide 530 can be prevented. Note that although a structure in which both the Al side and the A2 side of the upper portion of the oxide 530 have a curved shape is employed in Patent Document 1 and Patent Document 2, one embodiment of the present application is not limited to this. For example, a structure in which one of the Al side and the A2 side of the upper portion of the oxide 530 has a curved shape is sometimes employed.

[0371] Here, an example of a structure in which the oxide 530 includes the oxide 530a, the oxide 530b in contact with the oxide 530a, and the oxide 530c in contact with the oxide 530b is shown.

[0372] At this time, for example, a film to be the oxide 530a and the oxide 530c can be formed by an atomic layer deposition (ALD) method and a film to be the oxide 530b can be formed by a sputtering method. Specifically, a film to be the oxide 530a can be deposited so as to have a composition of In:Zn = 2:1 [atomic ratio] or its vicinity. Alternatively, indium oxide can be used for the film to be the oxide 530a. Further, the oxide 530b can be deposited using an oxide target having a composition of In:Sn:Zn = 4:0.1:1 [atomic ratio] or its vicinity. Further, a film to be the oxide 530c can be deposited so as to have a composition of In:Zn = 2:1 [atomic ratio] or its vicinity. Alternatively, indium oxide can be used for the film to be the oxide 530c.

[0373] Next, heat treatment is preferably performed. The heat treatment is preferably performed in a temperature range in which the oxide 530 is not polycrystallized.

[0374] For example, as the heat treatment, treatment can be performed at a temperature of 450 °C for 1 hour in a flow ratio of nitrogen gas to oxygen gas of 4:1.

[0375] ​By depositing the oxide 530 by the above method and performing heat treatment, the oxide 530 can be made into AGCAAC. Thus, the on-state current, S value, field-effect mobility, frequency characteristics, and the like of the transistor 500F can be improved, and a semiconductor device with good electrical characteristics can be provided. Furthermore, a semiconductor device with high reliability can be provided.

[0376] In addition, when the oxide semiconductor is used as the oxide 530, as illustrated in FIGS. 5A and 5B, the insulator 545 preferably has a stacked structure of an insulator 545a in contact with the oxide 530, an insulator 545b over the insulator 545a, an insulator 545c over the insulator 545b, and an insulator 545d over the insulator 545c. Figure 15A and Figure 15B At this time, the insulator 545a and the insulator 545c preferably have a function of trapping or fixing hydrogen.

[0377] As the insulator having a function of trapping or fixing hydrogen, a metal oxide having an amorphous structure can be given. As the insulator 545a and the insulator 545c, for example, a metal oxide such as magnesium oxide or an oxide containing one or both of aluminum and hafnium is preferably used. The metal oxide having an amorphous structure has a property in which an oxygen atom has a dangling bond and traps or fixes hydrogen by the dangling bond. In other words, the metal oxide having an amorphous structure has high capability of trapping or fixing hydrogen.

[0378] The insulator 545a and the insulator 545c are preferably formed using a high-k material. As one example of the high-k material, an oxide containing one or both of aluminum and hafnium is given. When the high-k material is used as the insulator 545a and the insulator 545c, the gate potential applied at the time of transistor operation can be reduced while the physical thickness of the gate insulating film is kept. Furthermore, the equivalent oxide thickness (EOT) of the insulator used as the gate insulating film can be reduced.

[0379] As the insulator 545a and the insulator 545c, an oxide containing one or both of aluminum and hafnium is preferably used, and an oxide having an amorphous structure and containing one or both of aluminum and hafnium is more preferably used.

[0380] As the insulator 545a, an aluminum oxide film can be used, for example. Furthermore, the aluminum oxide preferably has an amorphous structure. Here, by providing the insulator 545a in contact with the oxide 530, the insulator 545a can more effectively trap and fix hydrogen contained in the oxide 530 and the like.

[0381] The insulator 545c can be appropriately formed using hafnium oxide, for example. Here, by providing the insulator 545c between the insulator 545b and the insulator 545d, hydrogen contained in the insulator 545b or the like can be more effectively trapped and fixed.

[0382] Next, a thermally stable insulator such as silicon oxide or silicon oxynitride is preferably used as the insulator 545b. A silicon oxide film used as the insulator 545b is preferably formed using a PEALD method.

[0383] Further, in order to suppress oxidation of the conductive object 542a, the conductive object 542b, and the conductive object 560, an oxygen barrier insulator is preferably provided in the vicinity of each of the conductive object 542a, the conductive object 542b, and the conductive object 560. For example, an oxygen barrier insulator can be provided in the insulator 545a, the insulator 545d, the insulator 545c, and the insulator 544.

[0384] Note that in this specification and the like, an insulator having a barrier property refers to an insulator having a property of blocking the transmission of a corresponding substance (also referred to as low transmission). For example, an insulator having a barrier property has a property that a corresponding substance is not easily diffused into the inside of the insulator. For example, an insulator having a barrier property has a function of trapping or fixing (also referred to as gettering) a corresponding substance in the inside of the insulator.

[0385] As the oxygen barrier insulator, for example, an oxide containing one or both of aluminum and hafnium, magnesium oxide, gallium oxide, silicon nitride, and silicon oxynitride can be given. Further, as the oxide containing one or both of aluminum and hafnium, for example, aluminum oxide, hafnium oxide, an oxide containing aluminum and hafnium (hafnium aluminate), and an oxide containing hafnium and silicon (hafnium silicate) can be given. For example, the insulator 545a, the insulator 545c, the insulator 545d, and the insulator 544 preferably have a single-layer structure or a stacked-layer structure of the above-described oxygen barrier insulator.

[0386] The insulator 545a preferably has a barrier property against oxygen. The insulator 545a is preferably less likely to transmit oxygen than the insulator 580. The insulator 545a includes a region in contact with a side surface of the conductive object 542a and a side surface of the conductive object 542b. When the insulator 545a has a barrier property against oxygen, the side surfaces of the conductive object 542a and the conductive object 542b can be prevented from being oxidized to form an oxide film on the side surfaces. Thus, a decrease in on-state current or a decrease in field-effect mobility of the transistor 500F can be suppressed.

[0387] Further, the insulator 545a is provided in contact with the top surface and side surface of the oxide 530 and the top surface of the insulator 522. When the insulator 545a is oxygen-blocking, oxygen can be prevented from being released from the channel formation region of the oxide 530 at the time of heat treatment or the like. Thus, the formation of oxygen vacancies in the oxide 530 can be reduced.

[0388] Further, by providing the insulator 545a, excessive oxygen is prevented from being supplied from the insulator 580 to the oxide 530, so that an appropriate amount of oxygen can be supplied to the oxide 530. Thus, a decrease in on-state current or a decrease in field-effect mobility of the transistor 500F due to over-oxidation of the source region and the drain region can be suppressed.

[0389] Since an oxide containing one or both of aluminum and hafnium is oxygen-blocking, it can be appropriately used as the insulator 545a.

[0390] The insulator 545d is preferably also oxygen-blocking. The insulator 545d is provided between the channel formation region of the oxide 530 and the conductor 560 and between the insulator 580 and the conductor 560. With this structure, oxygen in the channel formation region of the oxide 530 can be prevented from diffusing into the conductor 560 and forming oxygen vacancies in the channel formation region of the oxide 530. Further, oxygen in the oxide 530 and oxygen in the insulator 580 can be prevented from diffusing into the conductor 560 and causing oxidation of the conductor 560. The insulator 545d is preferably less likely to transmit oxygen than the insulator 580. For example, a silicon nitride film is preferably used as the insulator 545d. At this time, the insulator 545d is an insulator containing at least nitrogen and silicon.

[0391] Further, the insulator 545d is preferably hydrogen-blocking. With this, impurities such as hydrogen contained in the conductor 560 can be prevented from diffusing into the oxide 530.

[0392] The insulator 544 is preferably also oxygen-blocking. The insulator 544 is provided between the insulator 580 and the conductor 542a and between the insulator 580 and the conductor 542b. The insulator 544 is provided in contact with the side surface of the conductor 542, the side surface of the oxide 530, and the top surface of the insulator 522. With this structure, oxygen contained in the insulator 580 can be prevented from diffusing into the conductor 542. Thus, oxidation of the conductor 542 due to oxygen contained in the insulator 580 can be prevented, so that the specific resistivity can be increased. The insulator 544 is preferably less likely to transmit oxygen than the insulator 580. For example, silicon nitride is preferably used as the insulator 544. At this time, the insulator 544 is an insulator containing at least nitrogen and silicon.

[0393] In order to suppress a decrease in the hydrogen concentration in the source region and the drain region in the oxide 530, it is preferable to provide a hydrogen-blocking insulator in the vicinity of the source region and in the vicinity of the drain region. For example, a hydrogen-blocking insulator is used as the insulator 544.

[0394] As the hydrogen-blocking insulator, an oxide such as aluminum oxide, hafnium oxide, and tantalum oxide, and a nitride such as silicon nitride can be given. For example, a single-layer structure or a stacked-layer structure of a hydrogen-blocking insulator is preferably employed as the insulator 544.

[0395] By providing the above-described insulator 544, the hydrogen diffusion from the source region and the drain region to the outside can be reduced, and thus a decrease in the hydrogen concentration in the source region and the drain region can be suppressed. Thus, the source region and the drain region can be n-type.

[0396] With the above structure, the channel formation region can be i-type or substantially i-type and the source region and the drain region can be n-type, and thus a semiconductor device with good electrical characteristics can be provided. With the above structure, even if the semiconductor device is miniaturized or highly integrated, the semiconductor device can have good electrical characteristics. Further, by miniaturizing the transistor 500F, the high-frequency characteristics can be improved. Specifically, the cutoff frequency can be increased.

[0397] The insulators 545a to 545d are used as part of the gate insulating film. The insulators 545a to 545d are provided in openings formed in the insulator 580 together with the conductor 560. In order to achieve miniaturization of the transistor 500F, the thickness of the insulators 545a to 545d is preferably small. Each of the thicknesses of the insulators 545a to 545d is preferably greater than or equal to 0.1 nm and less than or equal to 10 nm, more preferably greater than or equal to 0.1 nm and less than or equal to 5.0 nm, further preferably greater than or equal to 0.5 nm and less than or equal to 5.0 nm, still further preferably greater than or equal to 1.0 nm and less than 5.0 nm, and still further preferably greater than or equal to 1.0 nm and less than or equal to 3.0 nm. Note that at least a part of each of the insulators 545a to 545d can include a region with the above thickness.

[0398] Further, the thickness of the silicon oxide film used as the insulator 545 is preferably greater than or equal to 0.7 nm and less than or equal to 3 nm.

[0399] In order to reduce the thickness of the insulators 545a to 545d as described above, deposition by an ALD method is preferable. Further, in order to provide the insulators 545a to 545d in the openings of the insulator 580 and the like, deposition by an ALD method is preferable. By depositing the insulator 545 by an ALD method, deposition with high coverage can be performed on the side surfaces of the first opening portion formed in the insulator 580, the side end portion of the conductor 542a, the side end portion of the conductor 542b, and the like.

[0400] Note that the insulator 545 is described above as having the four-layer structure of the insulator 545a to the insulator 545d, but one embodiment of the present application is not limited to this structure. The insulator 545 can have a structure including at least one of the insulator 545a to the insulator 545d. By forming the insulator 545 with one layer, two layers, or three layers of the insulator 545a to the insulator 545d, the manufacturing process of the transistor 500F can be simplified, which can increase the yield of semiconductor devices including the transistor 500F.

[0401] As Figure 14A indicated in FIG. 5A, the shape of the oxide 530 in plan view is preferably a circular shape (which can also be referred to as a frame shape, a ring shape, a circle shape, or a closed curve shape). That is, the oxide 530 preferably has a plurality of portions extending in the channel width direction and a plurality of portions extending in the channel length direction. With such a structure in which the oxide 530 has a high aspect ratio, the oxide 530 can be prevented from falling down in the manufacturing process of the transistor. Figure 14A As Figure 14A indicated in FIG. 5B, the oxide 530 has an opening in the central portion. In this embodiment, the shape of the oxide 530 in plan view is a line-symmetrical shape with A1-A2 as the center, but one embodiment of the present application is not limited to this shape. For example, the shape of the oxide 530 in plan view can be an asymmetric shape.

[0402] Figure 14A The structure illustrated in FIG. 5C is a structure in which two circular oxides 530 are formed in the channel width direction. As Figure 14A indicated in FIG. 5D, the oxide 530 preferably overlaps with the conductor 560 at two or more points in plan view. Thus, the conductor 560 preferably includes two or more regions overlapping with the oxide 530. In other words, the oxide 530 and the conductor 560 preferably overlap with each other at two or more regions.

[0403] With such a structure, as Figure 14B indicated in FIG. 5E, a plurality of fin-shaped oxides 530 are formed when viewed in cross section in the channel width direction. The plurality of fin-shaped oxides 530 each include a channel formation region. In other words, the transistor 500F is used as a multi-channel transistor. Thus, the channel width can be further increased in the transistor 500F, so that the on-state current can be increased. Thus, the operating speed of a semiconductor device including the transistor 500F can be increased.

[0404] Here, a structure in which two peripheral oxide 530s are provided is described, but one embodiment of the present application is not limited to this. For example, a structure in which one or more than three peripheral oxide 530s are provided can be employed. Further, the peripheral oxide 530s can be connected to form an oxide 530 having a shape including a plurality of openings. Further, an oxide 530 whose shape in plan view is a lattice shape can be used.

[0405] The insulator 584, the insulator 582, the insulator 522, and the insulator 521 preferably each include an insulator having a function of inhibiting diffusion of impurities such as water, hydrogen, and oxygen, and for example, an aluminum oxide, a magnesium oxide, a hafnium oxide, a zirconium oxide, an oxide containing aluminum and hafnium (hafnium aluminate), an oxide containing hafnium and zirconium (hafnium zirconium oxide), a gallium oxide, silicon nitride, silicon nitride oxide, or the like can be used. For example, the insulator 584 and the insulator 521 preferably use silicon nitride or the like which has higher hydrogen barrier properties. Further, for example, the insulator 582 preferably uses an aluminum oxide or the like which has high capability of trapping or fixing hydrogen. Further, for example, the insulator 522 preferably uses a hafnium oxide or the like which has high capability of trapping or fixing hydrogen and is a high-k material.

[0406] Note that as at least one of the insulator 521 and the insulator 522, a stacked structure of a silicon oxide and a silicon oxynitride can be used in addition to the above-described materials. For example, a stacked structure of silicon nitride and a silicon oxide can be used as the insulator 521. Further, for example, a stacked structure of a hafnium oxide and a silicon oxide can be used as the insulator 522.

[0407] With such a structure, diffusion of impurities such as water and hydrogen from an interlayer insulating film or the like provided above the insulator 584 to the transistor 500F or the like can be inhibited. Further, diffusion of impurities such as water and hydrogen from an interlayer insulating film or the like provided below the insulator 521 to the transistor 500F or the like can be inhibited. Further, hydrogen in the insulator 580 and the insulator 545 or the like can be trapped or fixed in the insulator 582 or the insulator 522. Further, by provision of the insulator 582 and the insulator 584, diffusion of oxygen in the insulator 580 or the like to above the transistor 500F or the like can be inhibited. Further, by provision of the insulator 522 and the insulator 521, diffusion of oxygen in the oxide 530 or the like to below the transistor 500F or the like can be inhibited. Thus, by employing a structure in which the transistor 500F is surrounded by insulators having a function of inhibiting diffusion of impurities such as water, hydrogen, and oxygen, above and below, diffusion of excess oxygen and hydrogen to the oxide semiconductor can be reduced. Thus, improvement in electric characteristics and reliability of the semiconductor device can be achieved.

[0408] The dielectric constant of each of the insulator 516 and the insulator 580 is preferably lower than that of the insulator 522. By using a material with a low dielectric constant for an interlayer film, parasitic capacitance generated between wirings can be reduced.

[0409] For example, insulator 516 and insulator 580 preferably each contain one or more of silicon oxide, silicon oxynitride, fluorine-added silicon oxide, carbon-added silicon oxide, carbon and nitrogen-added silicon oxide, and porous silicon oxide.

[0410] In particular, silicon oxide and silicon oxynitride are preferred due to their thermal stability. They are also preferred because materials such as silicon oxide, silicon oxynitride, and porous silicon oxide readily form regions containing oxygen released during heating.

[0411] In addition, the top surfaces of insulators 516 and 580 can also be planarized.

[0412] The concentration of impurities such as water and hydrogen in the insulator 580 is preferably reduced. For example, silicon oxides such as silicon oxynitride are preferably used as the insulator 580.

[0413] In addition, such as Figures 16A to 16E As shown, in transistor 500F, an insulator 524 can also be provided under oxide 530. The planar shape of insulator 524 (here, the shape viewed from the Z direction) is the same as that of oxide 530, and in top view, insulator 524 overlaps with oxide 530. The bottom surface of insulator 524 contacts insulator 522, the side surface of insulator 524 contacts insulator 545 and conductor 542a, and the top surface of insulator 524 contacts the bottom surface of oxide 530. Furthermore, insulating material suitable for insulator 545b can also be used for insulator 524. For example, silicon oxide can be used as insulator 524. Figures 16A to 16E Corresponding to Figures 14A to 14E .also, Figure 17 Corresponding to Figure 15B Regarding Figures 16A to 16E and Figure 17 For matters not addressed below within the structure, please refer to the above section regarding... Figures 14A to 14E and Figure 15B Explanation, etc.

[0414] Here, as Figure 17 As shown, the thickness t2 of the insulator 545 at the bottom of the first opening is preferably thinner than the thickness t1 (length in the direction perpendicular to the surface of the insulator 524) of the insulator 524. By adopting this structure, the bottom surface of the conductor 560 (conductor 560a) located at the first opening can be lower than the bottom surface of the oxide 530 by the difference between thickness t1 and thickness t2 (t1-t2).

[0415] By arranging the bottom surface of the conductor 560 below the bottom surface of the oxide 530, a sufficient gate electric field can be applied to the upper end portion to the lower end portion of the oxide 530. In other words, in the opening of the insulator 580 or the like, the entire oxide 530 can be electrically surrounded by the electric field of the conductor 560 and used as a channel formation region. With this structure, the lower end portion of the oxide 530 can be prevented from being used as a parasitic channel, and thus the leakage current between the source and the drain can be reduced. Further, the transistor can be inhibited from being always on or the like due to the parasitic channel. That is, the electrical characteristics of the transistor 500F can be improved.

[0416] As described above, by using the upper end portion to the lower end portion of the oxide 530 as a channel formation region, the channel width can be increased. Thus, the on-state current, the transconductance, the frequency characteristics, or the like of the transistor 500F can be improved.

[0417] Note that in this specification and the like, a structure of a transistor in which a channel formation region is electrically surrounded by an electric field of a gate electrode is referred to as a surrounded channel (S-channel) structure. In the S-channel structure, a gate electrode is arranged so as to surround at least two surfaces of a channel (specifically, two surfaces, three surfaces, or four surfaces, or the like). With the S-channel structure, the resistance to short channel effects can be improved, in other words, a transistor in which short channel effects are less likely to occur can be realized.

[0418] The S-channel structure is a structure in which a channel formation region is electrically surrounded, and thus the structure can be regarded as substantially the same as a Gate All Around (GAA) structure or a Lateral Gate All Around (LGAA) structure. With the transistor 500F having the S-channel structure, the GAA structure, or the LGAA structure, a channel formation region formed at an interface between the oxide 530 and an insulator 545 serving as a gate insulating film or in the vicinity thereof can be provided over the entire bulk of the oxide 530. Thus, the current density flowing through the transistor can be increased, and thus the on-state current of the transistor or the field-effect mobility of the transistor can be improved. Further, in one embodiment of the present application, the oxide 530 has a CAAC structure and a fin shape. With this structure, it is likely that a current path flowing between a source and a drain of the transistor is parallel to the a-b plane of the crystal axis. In other words, the oxide semiconductor having the CAAC structure and the fin shape has a conduction path equivalent to that of a two-dimensional semiconductor material or the like. Further, by using such an oxide semiconductor, a device having a two-dimensional conduction property can be manufactured.

[0419] Further, as described above, Figures 18A to 18EAs shown in FIG. 5F, the conductive body 503 can also be provided under the insulator 521 in the transistor 500F. Note that Figures 18A to 18E corresponding to Figures 14A to 14E In the structure described in this embodiment, matters not mentioned below can be understood in accordance with the description of the structure described in Embodiment Mode 1. Figures 18A to 18E Figures 14A to 14E

[0420] As with the conductive body 560, the conductive body 503 includes a region serving as a gate electrode. The conductive body 560 is sometimes referred to as a first gate electrode (an upper gate electrode) of the transistor 500F, and the conductive body 503 is sometimes referred to as a second gate electrode (a lower gate electrode) of the transistor 500F. Further, the conductive body 560 is sometimes referred to as a gate electrode of the transistor 500F, and the conductive body 503 is sometimes referred to as a back gate electrode of the transistor 500F.

[0421] As with the insulator 545, the insulator 522 and the insulator 521 each include a region serving as a gate insulating film when the transistor 500F includes the conductive body 503 under the insulator 521. Specifically, a region of each of the insulator 522 and the insulator 521 overlapping with the conductive body 503 serves as a gate insulating film. Further, the insulator 545 is sometimes referred to as a first gate insulating film (an upper gate insulating film), and the insulator 522 and the insulator 521 are sometimes referred to as a second gate insulating film (a lower gate insulating film).

[0422] In the transistor 500F, the conductive body 503 is provided so as to overlap with the oxide 530 and the conductive body 560. In Figure 18C and Figure 18E , the conductive body 503 is provided inside a fourth opening portion reaching the insulator 514 through the insulator 516. Further, the fourth opening portion includes a region overlapping with the oxide 530 and a region extending along the channel width direction beyond the end portion of the oxide 530 when viewed from above. Thus, the conductive body 503 provided inside the fourth opening portion also includes a region overlapping with the oxide 530 and a region extending along the channel width direction beyond the end portion of the oxide 530 when viewed from above. The conductive body 503 also serves as a wiring.

[0423] As shown in Figure 18C and Figure 18E , the conductive body 503 preferably includes a conductive body 503a and a conductive body 503b. The conductive body 503a is provided so as to be in contact with the bottom and the side surface of the fourth opening portion. The conductive body 503b is provided so as to be embedded in a recess of the conductive body 503a formed along the bottom and the side surface of the fourth opening portion. Here, the height of the top surface of the conductive body 503 coincides with the height of the top surface of the insulator 516.

[0424] ​​Here, the conductive body 503a preferably includes a conductive material having a function of suppressing diffusion of impurities such as hydrogen atoms, hydrogen molecules, water molecules, nitrogen atoms, nitrogen molecules, nitrogen oxide molecules (N2O, NO, NO2, or the like), copper atoms, and the like. Alternatively, a conductive material having a function of suppressing diffusion of oxygen (at least one of, for example, oxygen atoms, oxygen molecules, and the like) is preferable.

[0425] By using a conductive material having a function of suppressing diffusion of hydrogen as the conductive body 503a, diffusion of impurities such as hydrogen included in the conductive body 503b to the oxide 530 through the insulator 516 and the like can be prevented. Further, by using a conductive material having a function of suppressing diffusion of oxygen as the conductive body 503a, oxidation of the conductive body 503b and a decrease in conductivity can be suppressed. As the conductive material having a function of suppressing diffusion of oxygen, for example, titanium, titanium nitride, tantalum, tantalum nitride, ruthenium, and ruthenium oxide can be given. The conductive body 503a can have a single-layer structure or a stacked-layer structure of the above-described conductive materials. For example, the conductive body 503a preferably includes titanium nitride.

[0426] Further, the conductive body 503b preferably uses a conductive material in which tungsten, copper, or aluminum is a main component. For example, the conductive body 503b preferably includes tungsten.

[0427] As described above, the conductive body 503 can be used as a second gate electrode. In this case, by independently changing the potential supplied to the conductive body 503 without linking it to the potential supplied to the conductive body 560, the threshold voltage of the transistor 500F can be controlled. In particular, by applying a negative potential to the conductive body 503, the threshold voltage of the transistor 500F can be made larger and the off-state current can be reduced. Thus, in the case where a negative potential is applied to the conductive body 503, the drain current at the potential of 0 V of the conductive body 560 can be reduced, as compared with the case where no negative potential is applied to the conductive body 503.

[0428] Further, the resistivity of the conductive body 503 is designed in accordance with the potential applied to the conductive body 503, and the thickness of the conductive body 503 is set in accordance with the resistivity. Further, the thickness of the insulator 516 is substantially the same as that of the conductive body 503. Here, it is preferable to reduce the thickness of the conductive body 503 and the insulator 516 within a range allowed by the design of the conductive body 503. By reducing the thickness of the insulator 516, the absolute amount of impurities such as hydrogen included in the insulator 516 can be reduced, and thus diffusion of the impurities to the oxide 530 can be suppressed.

[0429] Note that a stacked structure of conductors 503a and 503b is shown here, but the present invention is not limited thereto. Conductor 503 can have a single-layer structure or a stacked structure of three or more layers. For example, when conductor 503 has a three-layer stacked structure, the stacked structure of conductors 503a and 503b described above can be used, and a conductor containing the same material as conductor 503a can be provided on conductor 503b. In this case, the conductor can also be formed such that the top surface of conductor 503b is lower than the uppermost part of conductor 503a and is embedded in the recess formed by conductors 503a and 503b.

[0430] <Example 4 of semiconductor device structure>

[0431] The transistors connected to the wiring SIG of the semiconductor device 100 are not limited to the structural examples of transistors 600e and 500 described above.

[0432] Figure 19 This is a cross-sectional view showing an example of the structure of the wiring SIG of semiconductor device 100 connected to the gate of transistor 550. Figure 19 The diagram illustrates, as an example, a structure in which a wiring layer is disposed on the upper layer of a substrate including a portion of a transistor 550, and a semiconductor device 100 is disposed on the upper layer of the wiring layer. Furthermore, reference may be made as appropriate to the above description, and therefore its description is sometimes omitted here.

[0433] Figure 19 The diagram shows a substrate 311 including a portion of a transistor 550, the transistor 550, insulators 322, 324, and 326 on the transistor 550, a wiring layer on the insulator 326 (here referring to a layer including insulators 350, 352, 354, and conductor 356), and a semiconductor device 100 on the wiring layer. Furthermore, a cross-sectional view of the channel length direction of the transistor 550 is shown here. Figure 20 A cross-sectional view of the channel width direction of transistor 550 is shown.

[0434] Conductor 356 is embedded in insulators 354, 352, and 350. Conductor 330 is embedded in insulators 326 and 324. Conductor 328 is embedded in insulator 322, etc.

[0435] Conductors 356, 330 and 328 all have the function of plugs or wiring.

[0436] The wiring SIG (corresponding to the conductive body 670a) is connected to the gate of the transistor 550 (corresponding to the conductive body 316 described later) through the conductive body 614, the conductive body 612, the conductive body 610, the conductive body 356, the conductive body 330, and the conductive body 328.

[0437] In this case, the semiconductor device 100 can be provided over and in a manner overlapping with the transistor 550. Thus, for example, in the case where the transistor 550 is used for a memory device, the semiconductor device 100 can be provided in a manner that does not significantly increase the area overhead of the memory device. Thus, the memory device can be reduced in size.

[0438] [Transistor 550]

[0439] The transistor 550 is described.

[0440] As Figure 19 illustrated, the transistor 550 is provided over the substrate 311 and includes a conductive body 316 serving as a gate electrode, an insulator 315 serving as a gate insulating film, a semiconductor region 313 serving as a channel formation region, a low-resistance region 314a serving as one of a source region and a drain region, and a low-resistance region 314b serving as the other of the source region and the drain region.

[0441] Further, the transistor 550 can be either a p-channel transistor or an n-channel transistor. For example, by connecting the gate of an n-channel transistor 550 to the gate of a p-channel transistor 550, a CMOS circuit (e.g., a circuit in which transistors operate complementarily, a CMOS logic gate, or a CMOS logic circuit) can be formed.

[0442] Thus, for example, in the case where the transistor 550 is used for a memory device, the transistor can be used for forming a driver circuit for operating the memory device.

[0443] Further, the transistor 550 can have, for example, a so-called Fin structure in which the top surface and the side surface in the channel width direction of the semiconductor region 313 are covered with the conductive body 316 with the insulator 315 interposed therebetween, as Figure 20 illustrated. Thus, the effective channel width is increased, so that the on-state characteristics of the transistor 550 can be improved. Further, since the effect of the electric field of the gate electrode can be enhanced, the off-state characteristics of the transistor 550 can be improved.

[0444] For example, the transistor 550 preferably includes a semiconductor such as silicon or the like in the channel formation region of the semiconductor region 313, a region in the vicinity thereof, a low-resistance region 314a serving as one of the source region and the drain region, and a low-resistance region 314b serving as the other of the source region and the drain region, and preferably includes single crystal silicon. Alternatively, the transistor 550 can be formed using a material including germanium, silicon germanium, gallium arsenide, or gallium aluminum arsenide, for example. Alternatively, the transistor 550 can use silicon in which a stress is applied to a crystal lattice to control an effective mass by changing a crystal plane spacing. Alternatively, the transistor 550 can be a high electron mobility transistor (HEMT) using gallium arsenide, gallium aluminum arsenide, or the like, for example.

[0445] For example, in the low-resistance regions 314a and 314b, an element such as arsenic or phosphorus which imparts n-type conductivity or an element such as boron which imparts p-type conductivity is added to a semiconductor material applied to the semiconductor region 313.

[0446] As the conductor 316, a semiconductor material such as silicon to which an element such as arsenic or phosphorus which imparts n-type conductivity or an element such as boron which imparts p-type conductivity is added, for example, can be used. Further, a conductive material such as a metal material, an alloy material, a metal oxide material, or the like can be used.

[0447] Further, since the material of the conductor determines a work function, by selecting the material of the conductor, the threshold voltage of the transistor can be adjusted.

[0448] As the conductor 316, a material such as titanium nitride or tantalum nitride is preferably used, for example. Further, in order to have both conductivity and embeddability, a stack of a metal material such as tungsten or aluminum is preferably used, for example. In particular, from the viewpoint of heat resistance, a stack of tungsten is preferably used, for example.

[0449] The insulator 320, the insulator 322, the insulator 324, and the insulator 326 are sequentially stacked in a manner covering the transistor 550.

[0450] As the insulator 320, the insulator 322, the insulator 324, and the insulator 326, a material such as silicon oxide, silicon oxynitride, silicon nitride oxide, silicon nitride, aluminum oxide, aluminum oxynitride, aluminum nitride oxide, and aluminum nitride can be used, for example. In particular, from the viewpoint of heat stability, silicon oxide or silicon oxynitride is preferably used.

[0451] Note that in this specification and the like, silicon oxynitride refers to a material that contains oxygen and nitrogen as its constituent elements and in which the proportion of oxygen is higher than that of nitrogen. Further, note that in this specification and the like, silicon nitride oxide refers to a material that contains oxygen and nitrogen as its constituent elements and in which the proportion of nitrogen is higher than that of oxygen. Note that in this specification and the like, aluminum oxynitride refers to a material that contains oxygen and nitrogen as its constituent elements and in which the proportion of oxygen is higher than that of nitrogen. Further, note that in this specification and the like, aluminum nitride oxide refers to a material that contains oxygen and nitrogen as its constituent elements and in which the proportion of nitrogen is higher than that of oxygen.

[0452] The insulator 322 can also have a function of planarizing a step caused by the transistor 550 or the like provided below. For example, in order to improve the planarity of the top surface of the insulator 322, the top surface thereof can be planarized by a planarization treatment such as a chemical mechanical polishing (CMP) method.

[0453] As the insulator 324, an insulator having a barrier property which can prevent impurities such as hydrogen from diffusing from the substrate 311 or the transistor 550 or the like provided below to a region provided above the insulator 324 is preferably used.

[0454] As the insulator having a barrier property against hydrogen, silicon nitride formed by a chemical vapor deposition (CVD) method can be used. In addition, for example, a metal oxide such as aluminum oxide, hafnium oxide, tantalum oxide, or the like can be used.

[0455] Here, for example, hydrogen sometimes diffuses into a semiconductor element having an oxide semiconductor such as the transistor 600, resulting in a decrease in the characteristics of the semiconductor element. Thus, it is preferable that an insulator which inhibits diffusion of hydrogen be provided between a region where the transistor 600 is provided and a region where the transistor 550 is provided. Specifically, the insulator which inhibits diffusion of hydrogen is an insulator in which the amount of hydrogen released is small.

[0456] The dielectric constant of the insulator 326 is preferably lower than that of the insulator 324. For example, the relative dielectric constant of the insulator 326 is preferably lower than 4, further preferably lower than 3. For example, the relative dielectric constant of the insulator 326 is preferably 0.7 times or less, further preferably 0.6 times or less, of the relative dielectric constant of the insulator 324. By using a material with a low dielectric constant for the interlayer film, parasitic capacitance generated between wirings can be reduced.

[0457] The conductive body 328 is embedded in the insulator 320 and the insulator 322. In addition, the conductive body 330 is embedded in the insulator 324 and the insulator 326.

[0458] The conductive body 328 and the conductive body 330 each have a function of a plug or a wiring. As the conductive body 328 and the conductive body 330, for example, the same material as the conductive body 610, the conductive body 612, or the conductive body 614 can be used.

[0459] In addition, a wiring layer can be provided over the insulator 326 and the conductive body 330. For example, in Figure 19 The insulator 350, the insulator 352, and the insulator 354 are sequentially stacked. In addition, the conductive body 356 is embedded in the insulator 350, the insulator 352, and the insulator 354.

[0460] The conductive body 356 has a function of a plug or a wiring. As the conductive body 356, the same material as the conductive body 328 and the conductive body 330 can be used, for example. In particular, a conductive body having a barrier property against hydrogen is preferably used.

[0461] Further, as the insulator 350, the insulator 352, and the insulator 354, the same material as the insulator 324, the insulator 322, and the insulator 326 can be used, for example. In particular, an insulator having a barrier property against hydrogen is preferably used.

[0462] Here, the conductive body having a barrier property against hydrogen is formed in the opening of the insulator 350 having a barrier property against hydrogen. With this structure, the region where the transistor 550 is provided can be separated from the outside of the region by using the conductive body having a barrier property against hydrogen. Thus, diffusion of hydrogen to the outside of the region where the transistor 550 is provided can be inhibited.

[0463] As the conductive body having a barrier property against hydrogen, tantalum nitride or the like can be used. Further, a stack of tantalum nitride and tungsten having high conductivity can be used. By using the stack of tantalum nitride and tungsten as the conductive body, the conductive body can maintain the conductivity as a wiring and inhibit diffusion of hydrogen.

[0464] That is, by stacking tantalum nitride and tungsten as the conductive body 356, the conductive body can maintain the conductivity as a wiring and inhibit diffusion of hydrogen from the transistor 550. At this time, the tantalum nitride layer in the conductive body 356 having a barrier property against hydrogen is preferably in contact with the insulator 350 having a barrier property against hydrogen.

[0465] Note that a wiring layer including the conductive body 356 is described here, but is not limited thereto. The wiring layer including the conductive body 356 can not be provided, or two or more wiring layers similar to the wiring layer including the conductive body 356 can be provided.

[0466] Note that Figure 19 The transistor 550 illustrated is just an example and is not limited to this structure.

[0467] [Substrate]

[0468] As a substrate of a semiconductor device, a storage device, and the like including the semiconductor device, for example, a glass substrate, a quartz substrate, a sapphire substrate, a ceramic substrate, a metal substrate (for example, a stainless steel substrate, a substrate including a stainless steel foil, a tungsten substrate, a substrate including a tungsten foil, and the like), a semiconductor substrate (for example, a single crystal semiconductor substrate, a polycrystal semiconductor substrate, or a compound semiconductor substrate), or an SOI (SOI: Silicon on Insulator) substrate, and the like can be used. In addition, as the substrate, a plastic substrate having heat resistance can be used. As the glass substrate, for example, barium borosilicate glass, aluminosilicate glass, aluminoborosilicate glass, or sodium calcium glass can be given. In addition to the above, as the glass substrate, for example, a crystallized glass, or the like can be used.

[0469] In addition, as the substrate, for example, a flexible substrate, a bonding film, paper or a base film including a fibrous material, or the like can be used. For example, as the flexible substrate, the bonding film, or the base film, a plastic typified by polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethersulfone (PES), polytetrafluoroethylene (PTFE), or the like can be given. Alternatively, a synthetic resin such as an acrylic resin, or the like can be given. Alternatively, for example, polypropylene, polyester, polyvinyl fluoride, or polyvinyl chloride, or the like can be given. Alternatively, for example, polyamide, polyimide, an aromatic polyamide resin, an epoxy resin, an inorganic vapor deposition film, paper, or the like can be given. In particular, by using a semiconductor substrate, a single crystal substrate, or an SOI substrate, or the like to manufacture a transistor, a transistor with small variation in characteristics, size, or shape, high current capacity, and small size can be manufactured. When a circuit is formed using the above transistor, low power consumption of the circuit or high integration of the circuit can be realized.

[0470] In addition, as the substrate, a flexible substrate can be used, and one or more of a transistor, a resistor, and a capacitor, or the like can be directly formed over the flexible substrate. Alternatively, a separation layer can be provided between the substrate and one or more of a transistor, a resistor, and a capacitor, or the like. The separation layer can be used in the case where part or all of a semiconductor device is manufactured over the separation layer and then separated from the substrate and transferred to another substrate. At this time, one or more of a transistor, a resistor, and a capacitor, or the like can be transferred to a substrate with low heat resistance or a flexible substrate, or the like. In addition, as the separation layer, for example, a layered structure of an inorganic film of a tungsten film and a silicon oxide film, a structure in which an organic resin film of polyimide or the like is formed over a substrate, or a silicon film containing hydrogen, or the like can be used.

[0471] That is, the semiconductor device can also be transferred to another substrate after the semiconductor device is formed over one substrate. As a substrate to which the semiconductor device is transferred, not only the substrate over which the transistor can be formed as described above but also a paper substrate, a glassine substrate, an aramid film substrate, a polyimide film substrate, a stone substrate, a wood substrate, a cloth substrate (including natural fibers (silk, cotton, and hemp), synthetic fibers (nylon, polyurethane, and polyester), or regenerated fibers (acetate fiber, cupra fiber, rayon, and regenerated polyester)), a leather substrate, a rubber substrate, and the like can be used. By using these substracles, a semiconductor device with flexibility or a semiconductor device which is not easily broken can be manufactured. Further, heat resistance can be imparted to the semiconductor device. Further, weight reduction and thickness reduction of the semiconductor device can be achieved.

[0472] By providing the semiconductor device over a substrate with flexibility, a semiconductor device which is not easily broken and in which weight increase is suppressed can be provided.

[0473] Note that the semiconductor device according to one embodiment of the present application is not limited to the semiconductor device described in this embodiment. At least a part of the structure example, the operation example, the drawing, and the like corresponding to these examples described in this embodiment can be combined as appropriate with other structure examples, other operation examples, other drawings, and other embodiments described in this specification and the like.

[0474] (Embodiment 2)

[0475] In this embodiment, a transistor including an oxide semiconductor in a channel formation region (OS transistor) is described. Further, in the description of the OS transistor, a comparison with a transistor including silicon in a channel formation region (also referred to as Si transistor) is simply described.

[0476] [OS transistor]

[0477] An oxide semiconductor with low carrier concentration is preferably used for the OS transistor. For example, the carrier concentration of the channel formation region of the oxide semiconductor is 1 x 10 18 cm -3 Hereinafter, the carrier concentration is preferably lower than 1 x 10 17 cm -3 , more preferably lower than 1 x 10 16 cm -3 , still more preferably lower than 1 x 10 13 cm -3 , even still more preferably lower than 1 x 10 10 cm -3 , and 1 x 10 -9 cm -3In the above, in the case where the carrier concentration of the oxide semiconductor is reduced, the impurity concentration in the oxide semiconductor is preferably reduced so that the density of defect states in the oxide semiconductor is reduced. In this specification and the like, a state in which the impurity concentration and the density of defect states are both low is referred to as highly purified intrinsic or substantially highly purified intrinsic. Note that the oxide semiconductor in which the carrier concentration is low is also referred to as a highly purified intrinsic or substantially highly purified intrinsic oxide semiconductor.

[0478] Since the highly purified intrinsic or substantially highly purified intrinsic oxide semiconductor has a low density of defect states, it has a low density of trap states in some cases. Furthermore, a charge trapped in a trap state of an oxide semiconductor takes a long time to disappear, and in some cases, behaves like a fixed charge. Thus, the electrical characteristics of a transistor formed in an oxide semiconductor in which the density of trap states is high are unstable in some cases.

[0479] Thus, in order to stabilize the electrical characteristics of a transistor, it is effective to reduce the impurity concentration in an oxide semiconductor. In order to reduce the impurity concentration in an oxide semiconductor, it is preferable to reduce the impurity concentration in a film in the vicinity as well. As an impurity, for example, hydrogen, nitrogen, or the like can be given. Note that an impurity in an oxide semiconductor refers to, for example, an element other than the main components of the oxide semiconductor. For example, an element with a concentration lower than 0.1 atomic% can be regarded as an impurity.

[0480] In an OS transistor, when an impurity or an oxygen vacancy is present in a channel formation region of an oxide semiconductor, the electrical characteristics easily fluctuate and the reliability can be decreased. Furthermore, in an OS transistor, when hydrogen enters an oxygen vacancy in an oxide semiconductor and a defect (hereinafter referred to as V O H) is formed, an electron serving as a carrier can be generated. Furthermore, in an OS transistor, when V O H) is formed in a channel formation region, the donor concentration in the channel formation region is sometimes increased. Thus, in an OS transistor, as the donor concentration in the channel formation region is increased, the threshold voltage is sometimes not uniform. Thus, when an oxygen vacancy is included in a channel formation region of an oxide semiconductor, an OS transistor has a normally-on characteristic (a characteristic in which a drain current flows when a gate voltage is 0 V). Thus, in a channel formation region of an oxide semiconductor, it is preferable to reduce impurities, oxygen vacancies, and V O H) as much as possible.

[0481] Furthermore, the band gap of the oxide semiconductor is preferably larger than that of silicon (typically, 1.1 eV), preferably 2 eV or more, further preferably 2.5 eV or more, and still further preferably 3.0 eV or more. By using an oxide semiconductor having a larger band gap than silicon, the off-state current (also referred to as Ioff) of a transistor can be reduced.

[0482] For example, in a Si transistor, as the transistor is miniaturized, a short channel effect (SCE) occurs. Thus, it is difficult to miniaturize a Si transistor. As one of the reasons for the occurrence of the short channel effect, a small band gap of silicon can be given. On the other hand, in an OS transistor, an oxide semiconductor which is a semiconductor material having a large band gap is used, and thus the short channel effect can be suppressed. In other words, the OS transistor is a transistor in which the short channel effect does not occur or occurs little.

[0483] The short channel effect refers to a decrease in electrical characteristics that occurs as the transistor is miniaturized (reduction in the channel length). As specific examples of the short channel effect, for example, there are a decrease in threshold voltage, an increase in subthreshold swing value (sometimes referred to as S value), an increase in off-state current, and the like. Here, the S value refers to an amount of change in the gate voltage in a subthreshold region in which the value of the drain current is changed by one digit at a fixed drain voltage.

[0484] As an index of resistance to the short channel effect, a characteristic length is widely used. The characteristic length refers to an index of the curvature of potential in the channel formation region. The smaller the characteristic length, the more sharply the potential rises, and thus it can be said that the ability to resist the short channel effect is high.

[0485] The OS transistor is an accumulation type transistor, and the Si transistor is an inversion type transistor. Thus, the characteristic length between the source region and the channel formation region and the characteristic length between the drain region and the channel formation region are smaller in the OS transistor than in the Si transistor. Thus, the ability to resist the short channel effect is higher in the OS transistor than in the Si transistor. That is, when a transistor having a small channel length is to be manufactured, the OS transistor is more suitable than the Si transistor.

[0486] Even in the case where the carrier concentration of the oxide semiconductor is reduced to the channel formation region is i-type or substantially i-type, the conduction band bottom of the channel formation region is lowered due to a Conduction-Band-Lowering (CBL) effect in a short channel transistor, and thus the energy difference in the conduction band bottom between the source region or the drain region and the channel formation region can be reduced to 0.1 eV or more and 0.2 eV or less. Thus, the OS transistor can be regarded as an n + / n - / n + accumulation type junction-less transistor structure or an n + / n - / n + accumulation type non-junction transistor structure in which the channel formation region is an n - type region and the source region and the drain region are n +type region.

[0487] When the above structure is employed as the OS transistor, good electric characteristics can be achieved even if miniaturization or high integration is performed. For example, good electric characteristics can be obtained even if the gate length of the OS transistor is 20 nm or less, 15 nm or less, 10 nm or less, 7 nm or less, or 6 nm or less and 1 nm or more, 3 nm or more, or 5 nm or more. On the other hand, in the case of a Si transistor, it is sometimes difficult to have a gate length of 20 nm or less or 15 nm or less because of a short channel effect. Thus, the OS transistor can be used as a transistor with a small channel length as compared with the Si transistor. The gate length refers to the length of the gate electrode in the direction in which a carrier migrates inside the channel formation region when the transistor is in operation, that is, the width of the bottom surface of the gate electrode when the transistor is viewed from above.

[0488] Further, by miniaturizing the OS transistor, the high-frequency characteristics of the transistor can be improved. Specifically, the cutoff frequency of the transistor can be improved. When the gate length of the OS transistor is in the above range, the cutoff frequency of the transistor can be 50 GHz or more, preferably 100 GHz or more, and further preferably 150 GHz or more, for example, in a room-temperature environment.

[0489] As described above, the OS transistor has superior effects to the Si transistor, such as a small off-state current and the ability to manufacture a transistor with a small channel length.

[0490] The configuration, structure, or method described in this embodiment mode can be used in appropriate combination with the configuration, structure, or method described in other embodiment modes and the like.

[0491] (Embodiment 3)

[0492] A storage device of one embodiment of the present application is described in this embodiment.

[0493] <Structure Example of Storage Device>

[0494] A storage device 700 of one embodiment of the present application is described. The semiconductor device 100 and the like described in Embodiment Mode 1 can be used for at least a part of the storage device 700. In addition, the above transistor (the transistor 600, the transistor 500, the transistor 500F, the transistor 550, and the like) can be used.

[0495] Figure 21 is a block diagram illustrating a structure example of the storage device 700. Figure 21 The storage device 700 illustrated in FIG. 8A includes a memory array 721 and a driver circuit 722.

[0496] The memory array 721 includes a plurality of memory cells 741. The plurality of memory cells 741 is configured in a matrix of M rows by N columns. Here, M is an integer of 1 or more. N is an integer of 1 or more.

[0497] In addition, in Figure 21 In the drawing, a memory cell 741 [1, 1] arranged in the first row and the first column, a memory cell 741 [1, N] arranged in the first row and the N-th column, a memory cell 741 [M, 1] arranged in the M-th row and the first column, and a memory cell 741 [M, N] arranged in the M-th row and the N-th column are typically shown.

[0498] Further, Figure 21 A wiring WL[1] connected to the N memory cells 741 arranged in the first row, a wiring WL[M] connected to the N memory cells 741 arranged in the M-th row, a wiring BL[1] connected to the M memory cells 741 arranged in the first column, and a wiring BL[N] connected to the M memory cells 741 arranged in the N-th column are shown.

[0499] The driver circuit 722 includes a power switch 761, a power switch 762, and a peripheral circuit 771. The peripheral circuit 771 includes a peripheral circuit 781, a control circuit 772, and a voltage generation circuit 773.

[0500] In one embodiment of the present application, for example, a Si transistor (a transistor including silicon in a channel formation region) can be used as a transistor included in the driver circuit 722. Thus, for example, a CMOS circuit (e.g., a circuit which operates in complementarily, a CMOS logic gate, or a CMOS logic circuit) formed by connecting a gate of an n-channel Si transistor and a gate of a p-channel Si transistor can be used as the driver circuit 722.

[0501] As the Si transistor, for example, at least part of the transistor 550 and the like shown in Embodiment 1 described above can be used.

[0502] Here, for example, the memory array 721 can be stacked over the driver circuit 722 using a Si transistor by using an OS transistor (a transistor including an oxide semiconductor in a channel formation region) as a transistor included in the memory cell 741. Thus, the memory device 700 can be reduced in size. In addition, the wiring distance between the driver circuit 722 and the memory array 721 can be shortened. Accordingly, the memory device 700 can be improved in read speed, write speed, and the like.

[0503] As the OS transistor, for example, at least part of the transistor 600, the transistor 500, and the transistor 500F, and the like shown in Embodiment 1 described above can be used.

[0504] Further, although not shown, a configuration can also be employed in which, in the memory device 700, the memory array 721 includes a plurality of sense amplifiers configured in a matrix shape, and a plurality of memory cells 741 are stacked on the sense amplifiers. By employing such a configuration, a plurality of sense amplifiers can be accessed at the same time, and thus large-scale parallel reading of data stored in the memory array 721 can be performed.

[0505] The terminal BW, the terminal CE, the terminal GW, the terminal MCK, the terminal WAKE, the terminal ADDR, the terminal WDA, the terminal PON1, and the terminal PON2 are each supplied, for example, with a signal from the outside of the memory device 700. Further, a signal is output, for example, from the terminal RDA to the outside of the memory device 700.

[0506] The terminal MCK, for example, is supplied with a clock signal. Further, the terminal BW, the terminal CE, and the terminal GW are each supplied with a control signal. The terminal CE is supplied with a chip enable signal. The terminal GW is supplied with a global write enable signal. The terminal BW is supplied with a byte write enable signal. The terminal ADDR is supplied with an address signal. The terminal WDA is supplied with write data. The terminal RDA is supplied with read data. The terminal PON1 and the terminal PON2 are supplied with a signal for power gating control. Further, the signals supplied to the terminal PON1 and the terminal PON2 can also be generated, for example, in the control circuit 772.

[0507] The control circuit 772 has a function of controlling the operation of the memory device 700. The control circuit 772 has, for example, a function of logically operating the signals supplied to each of the terminal CE, the terminal GW, and the terminal BW to determine the operation mode (e.g., a write operation or a read operation) of the memory device 700. Further, it also has a function of generating a signal for controlling the peripheral circuit 781 to perform the operation mode.

[0508] The voltage generation circuit 773 has a function of generating an arbitrary potential for operating the drive circuit 722. The voltage generation circuit 773 has, for example, a function of generating an arbitrary potential from the clock signal input to the terminal MCK in accordance with a signal supplied to the terminal WAKE. The terminal WAKE is supplied, for example, with a signal for controlling whether or not the clock signal supplied to the terminal MCK is input to the voltage generation circuit 773.

[0509] The peripheral circuit 781 has a function of performing data write and read to the memory cell 741. The peripheral circuit 781 has, for example, a function of generating various signals for controlling the operation of the memory cell 741 and the like. The peripheral circuit 781 includes a row decoder 782, a column decoder 784, a row driver 783, a column driver 785, a data driver 786, an input circuit 787, and an output circuit 788.

[0510] The row decoder 782 and the column decoder 784 have a function of decoding the address signal supplied to the terminal ADDR. The row decoder 782 has a function of specifying a row to be accessed. The column decoder 784 has a function of specifying a column to be accessed. The row driver 783 has a function of selecting a row specified by the row decoder 782 and supplying a desired signal to, for example, the corresponding memory cell 741. The column driver 785 has a function of selecting a column specified by the column decoder 784 and supplying a desired signal to, for example, the corresponding memory cell 741.

[0511] The data driver 786 has a function of writing and reading data to and from the memory cell 741 selected by the row driver and the column driver. The input circuit 787 has a function of holding data supplied from the outside of the storage device 700 to the terminal WDA. The data held in the input circuit 787 (data Din) is written to the memory cell 741 through the data driver 786. The data stored in the memory cell 741 is read out to the output circuit 788 through the data driver 786. The output circuit 788 has a function of holding the data read out (data Dout). Further, it also has a function of outputting the held data to the outside of the storage device 700 from the terminal RDA.

[0512] Figure 21 The illustrated storage device 700 has, for example, a function of supplying a desired signal to the wiring WL[1] to the wiring WL[M] through the row driver 783 and has a function of exchanging data with the wiring BL[1] to the wiring BL[N] through the column driver 785 and the data driver 786.

[0513] The power switch 761 has a function of controlling whether or not to supply the potential supplied to the terminal VMD to the peripheral circuit 771. The power switch 762 has a function of controlling whether or not to supply the potential supplied to the terminal VMH to the row driver 783. Here, for example, the terminal VMD is supplied with a high power supply potential (for example, a potential VDD) used to operate the driver circuit 722, and the terminal VMS is supplied with a low power supply potential (for example, a potential VSS). Further, for example, the terminal VMH is supplied with a high power supply potential (for example, a potential higher than the potential VDD) used to operate the memory cell 741 and the like. The on state and the off state of the power switch 761 are controlled in accordance with a signal supplied to the terminal PON1. The on state and the off state of the power switch 762 are controlled in accordance with a signal supplied to the terminal PON2.

[0514] In the driver circuit 722, each of the above-described circuits and terminals can be appropriately selected. Further, other circuits and other terminals can also be appropriately added.

[0515] For example, one embodiment of the present application can use the semiconductor device 100 shown in Embodiment 1 for at least part of the wirings WL[1] to WL[M], the wirings BL[1] to BL[N], a wiring through which a signal is transmitted and received between the driver circuit 722 and the memory array 721, a wiring through which a signal is exchanged between the circuits included in the driver circuit 722, and a wiring through which a signal is exchanged with the outside of the memory device 700. In that case, the wiring corresponds to the wiring SIG included in the semiconductor device 100. Thus, by using the semiconductor device 100 for the memory device 700 and using the semiconductor device 100 as an ESD protection circuit, the reliability of the memory device 700 can be improved while suppressing an increase in power consumption, an increase in process cost, and an increase in the occupied area.

[0516] <Structure Example of Memory Cell>

[0517] A structure example of a memory cell 741 is described. As a transistor included in the memory cell described below, an OS transistor can be used. For example, at least part of the transistor 600, the transistor 500, and the transistor 500F described in Embodiment 1 can be used. Note that a memory device in which an OS transistor is used for a memory cell is called an OS memory.

[0518] Figure 22A The memory cell 950a includes a transistor M911 and a capacitor C911. One of a source and a drain of the transistor M911 is connected to one terminal of the capacitor C911. The other of the source and the drain of the transistor M911 is connected to a wiring BL serving as a bit line. A gate of the transistor M911 is connected to a wiring WL serving as a word line. The other terminal of the capacitor C911 is connected to a wiring CL. Note that the wiring in which one of the source and the drain of the transistor M911 and one terminal of the capacitor C911 are connected to each other is sometimes referred to as a wiring MN and described.

[0519] In the memory cell 950a, data of two values can be stored by setting the potential level corresponding to the amount of charge stored in the capacitor C911, that is, the amount of charge held in the wiring MN, to "1" or "0", respectively. Note that data of three or more values can be stored, for example. Further, in the case where data is written to the memory cell 950a, the amount of charge corresponding to the data is supplied from the wiring BL to the wiring MN by controlling the on / off state of the transistor M911, whereby the charge corresponding to the potential can be held. Further, in the case where data is read from the memory cell 950a, the charge held in the wiring MN can be extracted to the wiring BL by controlling the on / off state of the transistor M911.

[0520] By reading out data from the memory cell 950a, the charge held in the wiring MN is extracted to the wiring BL, whereby the potential of the wiring MN changes. That is, by reading out data from the memory cell 950a, the stored data is destroyed. That is, when data is read out from the memory cell 950a, destructive readout is performed. Therefore, after data is read out from the memory cell 950a, write back (refresh) of data needs to be performed.

[0521] In one embodiment of the present application, for example, an n-channel OS transistor can be used as the transistor M911.

[0522] Figure 22A The memory cell 950a illustrated is a memory cell of a DRAM (Dynamic Random Access Memory), and in particular, a structure in which an OS transistor is used as the transistor M911 is sometimes referred to as a DOSRAM (registered trademark). The DOSRAM uses an OS transistor whose off-state current is extremely small, and thus can store data for a long period of time. Furthermore, multi-value data or analog data can be stored. Moreover, since data that has been written can be stored for a long period of time, the refresh frequency of data can be reduced. Furthermore, since the static capacitance of the cell capacitance (the capacitor C911) can be reduced, the cell size can be reduced. Thus, by using a DOSRAM, reduction in power consumption and increase in storage density of a semiconductor device and a memory device can be achieved.

[0523] Figure 22B The memory cell 950b illustrated is a memory cell of a DRAM (Dynamic Random Access Memory), and in particular, a structure in which an OS transistor is used as the transistor M911 is sometimes referred to as a DOSRAM (registered trademark). The DOSRAM uses an OS transistor whose off-state current is extremely small, and thus can store data for a long period of time. Furthermore, multi-value data or analog data can be stored. Moreover, since data that has been written can be stored for a long period of time, the refresh frequency of data can be reduced. Furthermore, since the static capacitance of the cell capacitance (the capacitor C911) can be reduced, the cell size can be reduced. Thus, by using a DOSRAM, reduction in power consumption and increase in storage density of a semiconductor device and a memory device can be achieved. Figure 22A A variation of the memory cell 950a illustrated, which is different from the memory cell 950b, is a memory cell in which the capacitor C911 is not included.

[0524] In the memory cell 950b illustrated, the charge can be stored in a parasitic capacitor (static capacitance between one of the source and the drain of the transistor M911 and the gate) or the like indicated by a dashed line. By adopting such a structure, for example, the cell size can be reduced, and thus the storage density of a semiconductor device and a memory device can be increased. Figure 22B In the memory cell 950b illustrated, the charge can be stored in a parasitic capacitor (static capacitance between one of the source and the drain of the transistor M911 and the gate) or the like indicated by a dashed line. By adopting such a structure, for example, the cell size can be reduced, and thus the storage density of a semiconductor device and a memory device can be increased.

[0525] Figure 22CThe storage unit 950c illustrated includes the transistor M921, the transistor M922, and the capacitor C921. One of a source and a drain of the transistor M921 is connected to a gate of the transistor M922 and one terminal of the capacitor C921. The other of the source and the drain of the transistor M921 is connected to a wiring WBL serving as a bit line for writing. A gate of the transistor M921 is connected to a wiring WWL serving as a word line for writing. One of a source and a drain of the transistor M922 is connected to a wiring RBL serving as a bit line for reading. The other of the source and the drain of the transistor M922 is connected to a wiring PL. The other terminal of the capacitor C921 is connected to a wiring RWL serving as a word line for reading. Note that a wiring connecting one of the source and the drain of the transistor M921, the gate of the transistor M922, and one terminal of the capacitor C921 to each other is sometimes referred to as a wiring MN and described.

[0526] In the storage unit 950c, data of two values can be stored by setting the potential level corresponding to the amount of charge stored in the capacitor C921, that is, the amount of charge held in the wiring MN, to "1" or "0", for example. Note that data of three or more values can be stored, for example. Further, in the case of writing data into the storage unit 950c, the on-state of the transistor M921 is controlled, and a potential corresponding to the data is supplied from the wiring WBL to the wiring MN, whereby the charge corresponding to the potential can be held. Further, in the case of reading data from the storage unit 950c, the transistor M922 is made to be in an on-state or an off-state in accordance with the potential of the wiring MN, whereby a potential corresponding to the data can be extracted to the wiring RBL.

[0527] In one embodiment of the present application, an n-channel OS transistor can be used as the transistor M921, for example. Further, an n-channel transistor (e.g., an OS transistor or a Si transistor) can be used as the transistor M922, for example.

[0528] Figure 22C The storage unit 950c illustrated is a gain cell type storage unit, and in particular, a structure using an OS transistor as the transistor M921 is sometimes referred to as NOSRAM (registered trademark). NOSRAM is an acronym of Nonvolatile Oxide Semiconductor RAM. NOSRAM uses an OS transistor whose off-state current is small, and thus can store data for a long time. Further, multi-value data or analog data can be stored. Further, since the transistor for writing (the transistor M921) is different from the transistor for reading (the transistor M922), non-destructive reading can be performed at the time of reading data. Thus, NOSRAM can be used as a nonvolatile memory, for example.

[0529] Figure 22D The storage unit 950d illustrated isFigure 22C A modification example of the storage unit 950c is shown in FIG. 9D. The storage unit 950d differs from the storage unit 950c in that the storage unit 950d does not include the capacitor C921. Further, the storage unit 950d differs from the storage unit 950c in that the other of the source and the drain of the transistor M922 is connected to the wiring RWL.

[0530] In the storage unit 950d shown in FIG. 9D, charge can be stored in a parasitic capacitor added to the wiring MN. With such a structure, for example, the cell size can be reduced, and thus the storage density of the semiconductor device and the memory device can be increased. Figure 22D

[0531] A modification example of the storage unit 950c is shown in FIG. 9E. The storage unit 950e differs from the storage unit 950c in that the other of the source and the drain of the transistor M921 is connected to the wiring BL and one of the source and the drain of the transistor M922 is connected to the wiring BL in the storage unit 950e. Figure 22E Figure 22C In the storage unit 950e shown in FIG. 9E, the wiring BL can be used as both a write bit line and a read bit line. With such a structure, for example, the cell size can be reduced, and thus the storage density of the semiconductor device and the memory device can be increased.

[0532] In the storage unit 950e shown in FIG. 9E, the wiring BL can be used as both a write bit line and a read bit line. With such a structure, for example, the cell size can be reduced, and thus the storage density of the semiconductor device and the memory device can be increased. Figure 22E

[0533] A modification example of the storage unit 950c is shown in FIG. 9F. The storage unit 950f differs from the storage unit 950c in that the storage unit 950f includes the transistor M922p instead of the transistor M922. For example, a p-channel Si transistor can be used as the transistor M922p. Figure 22F Figure 22C In the storage unit 950f shown in FIG. 9F, since data is read using a p-channel transistor, for example, the structure and operation of a read amplifier and the like can be simplified in some cases. With such a structure, for example, the layout area of a driver circuit can be reduced, and thus the semiconductor device and the memory device can be miniaturized.

[0534] In the storage unit 950f shown in FIG. 9F, since data is read using a p-channel transistor, for example, the structure and operation of a read amplifier and the like can be simplified in some cases. With such a structure, for example, the layout area of a driver circuit can be reduced, and thus the semiconductor device and the memory device can be miniaturized. Figure 22F

[0535] A modification example of the storage unit 950c is shown in FIG. 9G. The storage unit 950g differs from the storage unit 950c in that the storage unit 950g includes the transistor M921p instead of the transistor M921. For example, an n-channel Si transistor can be used as the transistor M921p. Figure 22G Figure 22B ​​​A modification example of the storage unit 950c is shown. The storage unit 950g differs from the storage unit 950c in that the storage unit 950g further includes a transistor M923. One of a source and a drain of the transistor M922 is connected to one of a source and a drain of the transistor M923, the other of the source and the drain of the transistor M922 is connected to a wiring PL, the other of the source and the drain of the transistor M923 is connected to a wiring RBL, and a gate of the transistor M923 is connected to a wiring RWL. For example, an n-channel transistor (e.g., an OS transistor or a Si transistor) can be used as the transistor M923.

[0536] In Figure 22G In the storage unit 950g, the parasitic capacitance between the wiring MN and the wiring RBL can be reduced. With such a structure, for example, noise mixed into the wiring MN through the gate capacitance of the transistor M922 can be suppressed, and thus the reliability of the semiconductor device and the storage device can be improved.

[0537] Figure 22H The storage unit 950h includes a transistor M931, a transistor M932, a transistor M933, a transistor M934, a capacitor C931, a capacitor C932, an inverter X931, and an inverter X932. One of a source and a drain of the transistor M931 is connected to one of a source and a drain of the transistor M933, an input terminal of the inverter X931, and an output terminal of the inverter X932. One of a source and a drain of the transistor M932 is connected to one of a source and a drain of the transistor M934, an output terminal of the inverter X931, and an input terminal of the inverter X932. The other of the source and the drain of the transistor M933 is connected to one terminal of the capacitor C931. The other of the source and the drain of the transistor M934 is connected to one terminal of the capacitor C932. The other of the source and the drain of the transistor M931 is connected to a wiring BL serving as one of a pair of bit lines. The other of the source and the drain of the transistor M932 is connected to a wiring BLB serving as the other of the pair of bit lines. A gate of the transistor M931 and a gate of the transistor M932 are connected to a wiring WL serving as a word line. A gate of the transistor M933 and a gate of the transistor M934 are connected to a wiring BRL. The other terminal of the capacitor C931 and the other terminal of the capacitor C932 are connected to a wiring CL.

[0538] The storage unit 950h can store data of two values of "1" or "0" in an inverter loop formed by the inverter X931 and the inverter X932. Further, in the case where data is written in the storage unit 950h, by controlling the on / off states of the transistor M931 and the transistor M932, a potential corresponding to the data can be supplied to the inverter loop from each of the wire BL and the wire BLB. Further, in the case where data is read from the storage unit 950h, by controlling the on / off states of the transistor M931 and the transistor M932, a potential corresponding to the data stored in the inverter loop can be extracted to each of the wire BL and the wire BLB.

[0539] Further, in the storage unit 950h, by controlling the on / off states of the transistor M933 and the transistor M934, one terminal of the capacitor C931 and one terminal of the capacitor C932 are supplied with potentials corresponding to the data stored in the inverter loop, respectively, so that charges corresponding to the potentials can be held. That is, data can be backed up. Further, in the storage unit 950h, by controlling the on / off states of the transistor M933 and the transistor M934, the charges held in one terminal of the capacitor C931 and one terminal of the capacitor C932, respectively, can be extracted to the inverter loop. That is, data can be restored.

[0540] In one embodiment of the present application, as the transistor M931, the transistor M932, the transistor M933, and the transistor M934, for example, an n-channel OS transistor can be used. Further, as the inverter X931 and the inverter X932, an inverter circuit prepared in a standard circuit library can be used. That is, as the transistors that constitute the inverter X931 and the inverter X932, for example, an n-channel Si transistor and a p-channel Si transistor can be used.

[0541] Figure 22H The storage unit 950h illustrated in the drawing is a storage unit of an SRAM (Static Random Access Memory) which can be backed up, and in particular, a structure in which an OS transistor is used as the transistor M931, the transistor M932, the transistor M933, and the transistor M934 is called an OS-SRAM (Oxide Semiconductor-SRAM).

[0542] Note that one embodiment of the present application is not limited to the storage units 950a to 950h, and can be a storage unit in which each structure is appropriately combined.

[0543] Note that one embodiment of the present application can be combined with other embodiments described in this specification and the like as appropriate.

[0544] (Embodiment 4)

[0545] An application example of a storage device according to one embodiment of the present application is described in this embodiment.

[0546] <Example of hierarchical structure of storage device>

[0547] In general, in a computer or the like, various storage devices are used according to their uses. Figure 23 Various storage devices are shown in a hierarchy. The higher the storage device is in the hierarchy, the faster the operation speed is required. The lower the storage device is in the hierarchy, the larger the storage capacity and the higher the storage density are required. In Figure 23 In the hierarchy, a register, a cache memory, a main memory, and a storage are shown in order from the top. Further, the cache memory can include, in order from the top, a level 1 cache (L1), a level 2 cache (L2), and a level 3 cache (L3), and the like. Note that although an example including at most a level 3 cache is shown here, a cache memory lower in the hierarchy can be included. The cache memory at the bottom of the hierarchy is sometimes referred to as an LLC (Last Level Cache) or an FLC (Final Level Cache). Further, for example, a storage level memory can be included between the main memory and the storage.

[0548] A register is incorporated into an arithmetic processing device (also referred to as a processor) such as a CPU (Central Processing Unit) or a GPU (Graphics Processing Unit), and is used to temporarily store an operation result in a core or the like. Further, the register has a function of holding setting information of the arithmetic processing device or the like. Thus, the access frequency from the arithmetic processing device is high. Therefore, the register is required to have a fast operation speed.

[0549] As a cache memory, an SRAM (Static Random Access Memory) is used, for example. The cache memory has a function of copying and holding a part of data held in the main memory. By copying data with a high use frequency, the access speed to the data can be improved. The cache memory is required to have a faster operation speed than the main memory.

[0550] As a main memory, a DRAM (Dynamic Random Access Memory) is used, for example. The main memory has a function of holding a program and data or the like read out from the storage. The main memory is required to have a larger storage capacity and a higher storage density than the cache memory.

[0551] The storage stores functions of holding data that needs to be kept for a long time and various programs and the like used by the arithmetic processing device. Thus, the storage is required to have a large storage capacity and a high storage density. As the storage, for example, an HDD (Hard Disk Drive) and an SSD (Solid State Drive) that is positioned above the HDD, and the like can be used. As the SSD, for example, a large-capacity, nonvolatile storage device such as a NAND-type flash memory (e.g., 3D NAND) can be used.

[0552] The storage device according to one embodiment of the present application has advantages of high operation speed, long-term data retention, high rewrite resistance, and low-voltage driving. The storage device according to one embodiment of the present application is suitable for use as a storage device positioned in a region (OS mem) including a level at which a cache memory is positioned, a level at which a main memory is positioned, and a level at which a storage is positioned.

[0553] Thus, for example, it is preferable to use the storage device according to one embodiment of the present application instead of a DRAM used for a main memory. Here, the DRAM is a storage device that needs refresh operation and performs destructive readout, and thus has high power consumption as compared with other storage devices. Thus, by not using the DRAM, power consumption can be reduced. For example, it is also preferable to use the storage device according to one embodiment of the present application instead of a part of an SRAM used for a cache memory and a part of a 3D NAND used for a storage.

[0554] One embodiment of the present application can not use a DRAM used for a main memory and the like in the past. At this time, the storage device according to one embodiment of the present application can be used instead of the DRAM. By adopting such a structure, power consumption can be significantly reduced (e.g., 1 / 100 or less, or 1 / 1000 or less). Thus, by spreading information processing devices including a computer, a server, and the like having such a structure throughout the world, global warming can be suppressed.

[0555] Note that one embodiment of the present application can be combined with other embodiments shown in this specification and the like as appropriate.

[0556] (Embodiment 5)

[0557] In this embodiment, electronic components, electronic devices, large computers, space devices, and data centers that can use the semiconductor device described in the above embodiment are described. The electronic components, electronic devices, large computers, space devices, and data centers that use the semiconductor device according to one embodiment of the present application are effective for realization of high performance such as low power consumption.

[0558] [Electronic Component]

[0559] Figure 24A is a perspective view of an electronic component 5700 and a substrate (circuit board 5704) on which the electronic component 5700 is mounted. Figure 24A The electronic component 5700 shown in the drawing includes a semiconductor device 5710 inside a mold 5711. Figure 24A In the drawing, a part of the electronic component 5700 is omitted to show the inside thereof. The electronic component 5700 includes a land 5712 outside the mold 5711. The land 5712 is connected to an electrode pad 5713. The electrode pad 5713 is connected to the semiconductor device 5710 through a lead 5714. The electronic component 5700 is mounted on a printed circuit board 5702, for example. By combining a plurality of such electronic components and connecting them on the printed circuit board 5702, a circuit board 5704 is completed.

[0560] Further, the semiconductor device 5710 includes a drive circuit layer 5715 and a memory layer 5716. Further, the memory layer 5716 has a structure in which a plurality of memory cell arrays are stacked. The stacked structure of the drive circuit layer 5715 and the memory layer 5716 can be a monolithic stacked structure. In the structure in which the layers are stacked in a monolithic manner, the layers can be connected to each other without using a through electrode technology such as a TSV (Through Silicon Via) and a bonding technology such as Cu-Cu direct bonding, for example. When the monolithic stacked structure of the drive circuit layer 5715 and the memory layer 5716 is adopted, a so-called on-chip memory structure in which a memory is directly formed on a processor can be realized, for example. By adopting the on-chip memory structure, high-speed operation of an interface portion of the processor and the memory can be realized.

[0561] Further, by adopting the on-chip memory structure, the size of a connection wiring and the like can be reduced compared to a technology using a through electrode such as a TSV, and thus the number of pins can be increased. By increasing the number of pins, parallel operation can be performed, and thus the bandwidth of the memory (also referred to as memory bandwidth) can be improved.

[0562] Further, it is preferable that a plurality of memory cell arrays in the memory layer 5716 be formed using OS transistors and stacked in a monolithic manner. When the plurality of memory cell arrays are stacked in a monolithic manner, one or both of the bandwidth of the memory and the access delay of the memory can be improved. The bandwidth refers to the amount of data transmission per unit time. Further, the access delay refers to the time between access and start of data transmission and reception. When Si transistors are used in the memory layer 5716, it is more difficult to realize a monolithic stacked structure compared to OS transistors. Therefore, in the monolithic stacked structure, OS transistors are superior to Si transistors.

[0563] In other words, OS transistors have superior effects such as a wider memory bandwidth compared to Si transistors.

[0564] Further, the semiconductor device 5710 can also be referred to as a die. In this specification and the like, a die refers to a chip obtained by cutting a circuit pattern formed on a substrate such as a disc-shaped substrate (also referred to as a wafer) or the like into a rectangular small piece in a manufacturing process of a semiconductor chip. As a semiconductor material that can be used for a die, for example, silicon, silicon carbide, gallium nitride, or the like can be given. For example, a die obtained from a silicon substrate (also referred to as a silicon wafer) is sometimes referred to as a silicon die.

[0565] Figure 24B is a perspective view of an electronic component 5730. The electronic component 5730 is one example of an SiP (System in Package) or an MCM (Multi Chip Module). In the electronic component 5730, an interposer 5731 is provided on a package substrate 5732 (a printed circuit board), and a semiconductor device 5735 and a plurality of semiconductor devices 5710 are provided on the interposer 5731.

[0566] In the electronic component 5730, the semiconductor device 5710 can be used as a storage device such as a high bandwidth memory (HBM) or the like, for example. Further, the semiconductor device 5735 can be used for an integrated circuit such as a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), or an FPGA (Field Programmable Gate Array) or the like (e.g., an arithmetic device, a control device, a signal processing device, or the like), for example.

[0567] The package substrate 5732 can use a ceramic substrate, a plastic substrate, a glass epoxy substrate, or the like, for example.

[0568] The interposer 5731 includes a plurality of wirings and has a function of connecting a plurality of integrated circuits each having a different terminal pitch. The plurality of wirings is constituted of a single layer or a plurality of layers. Further, the interposer 5731 has a function of connecting the integrated circuits provided on the interposer 5731 and electrodes provided on the package substrate 5732. Thus, the interposer 5731 is sometimes referred to as a "rewiring substrate" or an "intermediate substrate". Further, the integrated circuits and the package substrate 5732 are connected through a through electrode provided in the interposer 5731 and the through electrode, for example. Further, in the case where a silicon interposer is used as the interposer 5731, a TSV can be used as the through electrode.

[0569] As the interposer 5731, a silicon interposer is preferably used. Since the silicon interposer does not need to be provided with active elements, it can be manufactured at a lower cost than an integrated circuit. Further, wiring formation of the silicon interposer can be performed in a semiconductor process, and thus it is easy to form fine wiring that is difficult to form when a resin interposer is used.

[0570] In the HBM, many wirings need to be connected in order to achieve a wide memory bandwidth. For this reason, it is required that fine wirings can be formed at a high density on the interposer on which the HBM is mounted. Therefore, as the interposer on which the HBM is mounted, a silicon interposer is preferably used.

[0571] Further, for example, in a SiP or an MCM or the like using a silicon interposer, a decrease in reliability due to a difference in expansion coefficient between an integrated circuit and an interposer is less likely to occur. Further, since the surface planarity of the silicon interposer is high, connection failure is less likely to occur between an integrated circuit provided on the silicon interposer and the silicon interposer. It is particularly preferable to use a silicon interposer for 2.5D packaging (2.5D mounting) in which a plurality of integrated circuits are arranged in a horizontal direction and disposed on an interposer.

[0572] On the other hand, for example, when a plurality of integrated circuits having different terminal pitches are connected using a silicon interposer and a TSV or the like, a space of the width of the terminal pitch or the like is required. Therefore, when it is intended to reduce the size of the electronic component 5730, the width of the above-described terminal pitch becomes a problem, and it is sometimes difficult to provide a larger number of wirings required to achieve a wider memory bandwidth. Thus, as described above, a structure using a monolithic stack of OS transistors is preferable. Further, a composite structure in which a memory cell array stacked using a TSV is combined with a memory cell array stacked in a monolithic manner can also be adopted.

[0573] Further, a heat sink (heat spreader) can also be provided on a substrate on which the electronic component 5730 is mounted so as to overlap the electronic component 5730. In the case where the heat sink is provided, it is preferable to make the heights of integrated circuits provided on the interposer 5731 uniform. For example, in the electronic component 5730, it is preferable to make the heights of the semiconductor device 5710 and the semiconductor device 5735 uniform.

[0574] In order to mount the electronic component 5730 on another substrate, an electrode 5733 can also be provided on the bottom of the packaging substrate 5732. Figure 24B An example in which the electrode 5733 is formed using solder balls is shown. By providing solder balls in a matrix on the bottom of the packaging substrate 5732, the electronic component 5730 can be implemented as a BGA (Ball Grid Array) package. Further, the electrode 5733 can also be formed using conductive pins. By providing conductive pins in a matrix on the bottom of the packaging substrate 5732, the electronic component 5730 can be implemented as a PGA (Pin Grid Array) package.

[0575] The electronic component 5730 can be mounted on other substrates by various packaging methods, and is not limited to BGA or PGA. For example, SPGA (Staggered Pin Grid Array), LGA (Land Grid Array), QFP (Quad Flat Package), QFJ (Quad Flat J-leaded package), QFN (Quad Flat Non-leaded package), and the like can be used.

[0576] [Electronic device]

[0577] Figure 25A is a perspective view of an electronic device 6500. Figure 25A The electronic device 6500 illustrated is a portable information terminal device that can be used as a smartphone. The electronic device 6500 includes, for example, a housing 6501, a display portion 6502, a power button 6503, a button 6504, a speaker 6505, a microphone 6506, a camera 6507, a light source 6508, a control device 6509, and the like. The control device 6509 includes, for example, one or more selected from a CPU, a GPU, and a storage device. The semiconductor device of one embodiment of the present application can be used, for example, for the display portion 6502 or the control device 6509. By using the semiconductor device of one embodiment of the present application for the control device 6509, power consumption can be reduced, and thus the use is preferable.

[0578] Figure 25B is a perspective view of an electronic device 6600. Figure 25B The electronic device 6600 illustrated is an information terminal device that can be used as a notebook personal computer. The electronic device 6600 includes, for example, a housing 6611, a keyboard 6612, a pointing device 6613, an external connection port 6614, a display portion 6615, a control device 6616, and the like. The control device 6616 includes, for example, one or more selected from a CPU, a GPU, and a storage device. The semiconductor device of one embodiment of the present application can be used, for example, for the control device 6509 or the control device 6616. By using the semiconductor device of one embodiment of the present application for the control device 6616, power consumption can be reduced, and thus the use is preferable.

[0579] [Large computer]

[0580] Figure 25C is a perspective view of a large computer 5600. In Figure 25CIn the large-scale computer 5600, a plurality of rack-mounted computers 5620 are housed in a rack 5610. In addition, the large-scale computer 5600 can also be referred to as a supercomputer.

[0581] Figure 25D is a perspective view that illustrates an example of the structure of the computer 5620. In Figure 25D , the computer 5620 includes a motherboard 5630. The motherboard 5630 includes a plurality of slots 5631 and a plurality of connection terminals (not shown). The slots 5631 have personal computer cards 5621 inserted therein. Also, the personal computer cards 5621 include connection terminals 5623, connection terminals 5624, and connection terminals 5625, which are connected to the motherboard 5630.

[0582] Figure 25E The personal computer card 5621 illustrated is, for example, one example of a processing board that includes a CPU, a GPU, a storage device, and the like. The personal computer card 5621 includes a board 5622. In addition, the board 5622 includes the connection terminals 5623, the connection terminals 5624, the connection terminals 5625, a semiconductor device 5626, a semiconductor device 5627, a semiconductor device 5628, and connection terminals 5629. Note that, Figure 25E Semiconductor devices other than the semiconductor device 5626, the semiconductor device 5627, and the semiconductor device 5628 are illustrated, and the description of these semiconductor devices can be referred to the description of the semiconductor device 5626, the semiconductor device 5627, and the semiconductor device 5628 described below.

[0583] The connection terminals 5629 have a shape that can be inserted into the slots 5631 of the motherboard 5630, and the connection terminals 5629 are used as an interface that connects the personal computer cards 5621 and the motherboard 5630. As a specification of the connection terminals 5629, for example, PCIe (Peripheral Component Interconnect Express: high-speed serial computer expansion bus standard) or the like can be given.

[0584] The connection terminal 5623, the connection terminal 5624, and the connection terminal 5625 can each be used as an interface for supplying power or inputting a signal to the personal computer card 5621, for example. Further, for example, each can be used as an interface for outputting a signal calculated by the personal computer card 5621 or the like. As the specifications of the connection terminal 5623, the connection terminal 5624, and the connection terminal 5625, for example, a USB (Universal Serial Bus), a SATA (Serial ATA), a SCSI (Small Computer System Interface), or the like can be given. Further, when a video signal is output from each of the connection terminal 5623, the connection terminal 5624, and the connection terminal 5625, as the specifications, for example, an HDMI (registered trademark) (High-Definition Multimedia Interface) or the like can be given.

[0585] The semiconductor device 5626 includes a terminal (not illustrated) for inputting and outputting a signal, and the semiconductor device 5626 and the board 5622 can be connected by inserting the terminal into a socket (not illustrated) included in the board 5622.

[0586] The semiconductor device 5627 includes a plurality of terminals, and the semiconductor device 5627 and the board 5622 can be connected by soldering the terminals to wirings included in the board 5622 in a reflow soldering manner, for example. As the semiconductor device 5627, for example, an FPGA, a GPU, a CPU, or the like can be given. As the semiconductor device 5627, for example, the electronic component 5730 described above can be used.

[0587] The semiconductor device 5628 includes a plurality of terminals, and the semiconductor device 5628 and the board 5622 can be connected by soldering the terminals to wirings included in the board 5622 in a reflow soldering manner, for example. As the semiconductor device 5628, for example, a storage device or the like can be given. As the semiconductor device 5628, for example, the electronic component 5700 described above can be used.

[0588] The large-scale computer 5600 can be used as a parallel computer. By using the large-scale computer 5600 as a parallel computer, a large-scale computation required for learning and inference of artificial intelligence, for example, can be performed.

[0589] [Spacecraft]

[0590] A spacecraft such as an apparatus for processing and storing information or the like can be provided with the semiconductor device of one embodiment of the present application, for example.

[0591] The semiconductor device of one embodiment of the present application can include an OS transistor. The OS transistor has small fluctuation in electrical characteristics due to irradiation with a radiation line. In other words, the OS transistor has high resistance to a radiation line, and thus is suitable for use in an environment where a radiation line is likely to be incident. For example, the OS transistor is appropriately used in a case of use in space.

[0592] In Figure 26A , a satellite 6800 is shown as an example of a space device. The satellite 6800 includes a main body 6801, a solar battery panel 6802, an antenna 6803, a secondary battery 6805, and a control device 6807. In addition, Figure 26A An example in which a planet 6804 is present in space is shown. Note that space refers to, for example, an altitude of 100 km or more, but space shown in this specification and the like can include the thermosphere, the mesosphere, and the stratosphere.

[0593] In addition, although not shown in Figure 26A , a battery management system (also referred to as a BMS) or a battery control circuit can be provided in the secondary battery 6805. When an OS transistor is used for the above battery management system or battery control circuit, power consumption is low, and high reliability is achieved even in space, so it is preferable.

[0594] In addition, space is an environment in which the radiation dose is 100 times or more that of the ground. As a radiation line, for example, electromagnetic waves (electromagnetic radiation) typified by X-rays and γ-rays, and particle radiation typified by α-rays, β-rays, neutron beams, proton beams, heavy ion beams, and meson beams can be given.

[0595] The satellite 6800 generates power needed for the satellite 6800 to operate when sunlight is incident on the solar battery panel 6802. However, for example, in the case where sunlight is not incident on the solar battery panel 6802 or in the case where the amount of sunlight incident on the solar battery panel 6802 is small, the amount of power generated by the solar battery panel 6802 is reduced. Thus, it is possible that power needed for the satellite 6800 to operate is not generated. In order that the satellite 6800 operates even in the case where the amount of power generated by the solar battery panel 6802 is small, the secondary battery 6805 can be provided in the satellite 6800. In addition, the solar battery panel 6802 is sometimes referred to as a solar cell module.

[0596] The satellite 6800 can generate a signal. The signal is transmitted through the antenna 6803. In addition, for example, a receiver on the ground or another satellite can receive the signal. For example, by receiving the signal transmitted by the satellite 6800, the receiver can measure the position of the receiver that receives the signal. Thus, the satellite 6800 can constitute a satellite positioning system.

[0597] Further, the control device 6807 has a function of controlling the artificial satellite 6800. The control device 6807 is formed of one or a plurality of elements selected from a CPU, a GPU, and a storage device, for example. Further, it is preferable that a semiconductor device including an OS transistor of one embodiment of the present application be used for the control device 6807. The OS transistor has less fluctuation in electrical characteristics due to irradiation with a radiation line than a Si transistor. Thus, the OS transistor has high reliability even in an environment where a radiation line is likely to be incident, and is preferable.

[0598] In other words, the OS transistor has superior effects such as resistance to radiation lines, as compared to a Si transistor.

[0599] Further, the artificial satellite 6800 can include a sensor. For example, by including a visible light sensor, the artificial satellite 6800 can have a function of detecting sunlight reflected by an object on the ground. Alternatively, by including a thermal infrared sensor, the artificial satellite 6800 can have a function of detecting thermal infrared rays emitted from the ground surface. Thus, the artificial satellite 6800 can be used as an earth observation satellite, for example.

[0600] Note that the artificial satellite is illustrated here as an example of a space device, but the present application is not limited to this. For example, a semiconductor device of one embodiment of the present application can be used for a space device such as a spacecraft, a space capsule, a space probe, or the like.

[0601] 〔Data center〕

[0602] For example, a semiconductor device of one embodiment of the present application can be used for a storage system used in a data center or the like. A data center is required to ensure data immutability and the like for long-term management of data. In the long-term management of data, it is necessary to provide storage and servers for storing huge data, for example, to secure a stable power supply to keep data, or to secure a cooling device needed in keeping data, and the like. Thus, it is necessary to make facilities of the data center large, for example.

[0603] By using a semiconductor device of one embodiment of the present application for a storage system used in a data center, it is possible to reduce the power needed for keeping data, and to downsize the semiconductor device that keeps data. Thus, it is possible to downsize the storage system, to downsize a power supply for keeping data, to downsize a cooling device, and the like, for example. Thus, it is possible to save space in a data center.

[0604] Further, a semiconductor device of one embodiment of the present application has low power consumption, and thus it is possible to reduce heat generation in a circuit. Thus, it is possible to reduce negative effects on the circuit itself, a peripheral circuit, and a peripheral module due to the heat generation. Further, by using a semiconductor device of one embodiment of the present application, it is possible to realize a data center that operates stably even in a high-temperature environment. Thus, it is possible to improve the reliability of a data center.

[0605] Figure 26B A storage system usable for a data center is shown. Figure 26B The storage system 7000 shown includes a plurality of servers 7001sb as hosts 7001 (illustrated as host computers). In addition, a plurality of storage devices 7003md are included as storages 7003 (illustrated as storages). Furthermore, the hosts 7001 and the storages 7003 are connected through a storage area network 7004 (illustrated as SAN: Storage Area Network) and a storage control circuit 7002 (illustrated as storage controller).

[0606] The hosts 7001 correspond to computers that access data stored in the storages 7003. The hosts 7001 can also be connected to each other through a network.

[0607] In the storages 7003, the access speed of data, that is, the time required for writing or reading out data is shortened by using a flash memory, but the time is much longer than that required for a DRAM that can be used as a cache memory in a storage. In a storage system, in order to solve the problem of the longer access speed of the storages 7003, a cache memory is generally provided in a storage to shorten the time required for writing or reading out data.

[0608] The above cache memory is used in the storage control circuit 7002 and the storages 7003. Data exchanged between the hosts 7001 and the storages 7003 is output to the hosts 7001 or the storages 7003 after being stored in the cache memory in the storage control circuit 7002 and the storages 7003.

[0609] When an OS transistor is used as a transistor for storing data of the above cache memory to hold a potential corresponding to the data, the refresh frequency of the cache memory can be reduced to reduce the power consumption of the cache memory. Furthermore, the cache memory can be miniaturized by stacking an array of memory cells.

[0610] Note that power consumption reduction can be achieved by using the semiconductor device of one embodiment of the present application for one or more selected from an electronic component, an electronic device, a large computer, a space device, and a data center. Thus, it is currently considered that energy demand increases as semiconductor devices become higher in performance or higher in integration, and by using the semiconductor device of one embodiment of the present application, the amount of emission of greenhouse gases typified by carbon dioxide (CO2) can also be reduced. Furthermore, the semiconductor device of one embodiment of the present application has low power consumption, and thus is also effective as a measure against global warming.

[0611] The configuration, structure, or method shown in this embodiment mode can be used in appropriate combination with the configuration, structure, or method shown in other embodiment modes or the like.

[0612] (Additional Notes on Descriptions in This Specification, etc.)

[0613] The following additional notes are added to the description of each structure in the above embodiments and embodiments.

[0614] The "connection" in this specification includes, for example, an "electrical connection". In the case where the connection relationship of circuit elements is described as an "electrical connection" in order to define the connection relationship as an object, the "electrical connection" includes, for example, a "direct connection" and an "indirect connection". The "A is directly connected to B" means, for example, a case where A and B are connected without passing through a circuit element (for example, a transistor or a switch, etc. Note that a wiring is not a circuit element). On the other hand, the "A is indirectly connected to B" means, for example, a case where A and B are connected through one or more circuit elements.

[0615] Here, in the case where it is defined that "A is indirectly connected to B", it means, for example, a connection relationship in the following case. That is, when it is assumed that a circuit is operating, in the case where there is a timing at which electric signals are exchanged or electric potentials are interacted between A and B during the operation of the circuit, such a circuit can be defined as an object as "A is indirectly connected to B". Further, even in the case where there is no timing at which electric signals are exchanged or electric potentials are interacted between A and B, in the case where there is a timing at which electric signals are exchanged or electric potentials are interacted between A and B during the operation of the circuit, it can be defined as "A is indirectly connected to B". Note that the expression "A is indirectly connected to B" is defined as an object with respect to the connection relationship of circuit elements. Therefore, for example, even in the case where a circuit does not operate because a power supply voltage is not supplied, the circuit can be defined as an object as "A is indirectly connected to B" (however, for example, it is limited to the case where electric signals are exchanged or electric potentials are interacted between A and B during the operation of the circuit when the circuit operates because a power supply voltage is supplied).

[0616] Specific examples of the case of "indirect connection" are shown below. First, as an example of "A is indirectly connected to B", there is a case where Figure 27A1 and Figure 27A2Examples of indirect A-B connections include those where A and B are connected via the source and drain of one or more transistors. Other examples of indirect A-B connections include those where A and B are connected via one or more switches. In the case of indirect A-B connections, assuming the circuit is operational, at least one transistor between A and B is in an on-state, a conducting state, or a state where current can flow at least once. Furthermore, in the case of indirect A-B connections, there are also cases where one transistor between A and B is in an off-state or a non-conducting state. In the case of indirect A-B connections, if multiple transistors are connected between A and B, assuming the circuit is operational, each of the multiple transistors between A and B is in an on-state, a conducting state, or a state where current can flow at least once. In other words, in the case of indirect A-B connections, multiple transistors do not necessarily need to be in an on-state, a conducting state, or a state where current can flow simultaneously. Therefore, in the case of "A and B being indirectly connected," this includes situations where multiple transistors between A and B are simultaneously or at different times in a closed or non-conducting state. Other examples include... Figure 27A3 As shown, when A and C are connected through the source and drain of transistor TrP and B and C are connected through the source and drain of transistor TrQ, it can be defined as "A and C are indirectly connected", "B and C are indirectly connected", or "A and B are indirectly connected". Note that, as described below, when a fixed potential V is supplied to C from the power supply or GND, etc., although it can be said that "A and C are indirectly connected" or "B and C are indirectly connected", it is not possible to say that "A and B are indirectly connected".

[0617] The above examples illustrate situations where "indirect connection" can or cannot be described. However, the following examples show situations where "indirect connection" cannot be described. Even when electrical signals are exchanged or potentials interact between A and B during circuit operation, there are exceptions where "A and B are indirectly connected" cannot be described. An example of this exception is when A and B are connected through an insulator. That is, when A and B are connected through an insulator, "A and B are indirectly connected" cannot be described. Specific examples of A and B being connected through an insulator include... Figure 27A4 The case shown illustrates a capacitor connected between A and B. Other examples of A and B being connected via an insulator include... Figure 27A5 This refers to a situation where a gate insulating film of a transistor is sandwiched between A and B, as shown. In this case, it is not permissible to say that "A (the gate of the transistor) and B (the source or drain of the transistor) are indirectly connected".

[0618] As other examples of cases where it cannot be said that "A is indirectly connected to B", there are cases where no timing occurs in which an electric signal is transmitted and received between A and B or the potential of each of A and B interacts with each other. For example, there are cases where Figure 27A6 and Figure 27A7 as shown in FIG. 17A, a plurality of transistors are connected through the source and drain, and a fixed potential V is supplied from a power supply or GND or the like to the node between the transistors. In this case, although it cannot be said that "A is indirectly connected to B", it can be said that "A is indirectly connected to V" or "B is indirectly connected to V". In Figure 27A3 , in a case where A and C are connected through the source and drain of the transistor TrP, B and C are connected through the source and drain of the transistor TrQ, and a fixed potential V is supplied to C from a power supply or GND or the like, the same connection relationship as Figure 27A6 and Figure 27A7 is obtained, so it cannot be said that "A is indirectly connected to B" but it can be said that "A is indirectly connected to C" or "B is indirectly connected to C".

[0619] Although the above shows examples of "indirect connection", the definition of "indirect connection" is included in the definition of "electric connection", for example, so in a case where "A is indirectly connected to B", it can be said that "A is electrically connected to B".

[0620] Specific examples of cases of "direct connection" are shown below. As an example of a case where "A is directly connected to B", there are cases where A and B are not connected through a circuit element, as shown in Figure 27B1 , Figure 27B2 and Figure 27B3 . Further, in a case where A and B are not connected through a circuit element to a power supply or GND or the like that supplies a fixed potential V, it can be said that "A is directly connected to B", "A is directly connected to V", or "B is directly connected to V", as shown in Figure 27B4 and Figure 27B5 . Further, as shown in Figure 27B6 , even in a case where A (or B) is connected to a fixed potential V through the source and drain of a transistor, it can be said that "A is directly connected to B". Further, A and V or B and V are connected through the source and drain of a transistor, so it cannot be said that they are directly connected but it can be said that "A is indirectly connected to V" or "B is indirectly connected to V".

[0621] Although the above shows examples of "direct connection", the definition of "direct connection" is included in the definition of "electric connection", for example, so in a case where "A is directly connected to B", it can be said that "A is electrically connected to B".

[0622] Further, even when constituent elements independent on a circuit diagram are connected to each other, one constituent element sometimes has functions of a plurality of constituent elements. For example, when a part of a wiring functions as an electrode, one conductive film has functions of both the wiring and the electrode. Therefore, the category of "connection" in this specification and the like also includes a case where one conductive film has functions of a plurality of constituent elements.

[0623] In this specification and the like, a "resistor" includes, for example, a circuit element having a resistance value higher than 0 Ω or a wiring or the like having a resistance value higher than 0 Ω. Therefore, in this specification and the like, a "resistor" includes, for example, a wiring having a resistance value, a transistor in which current flows from a drain to a source, a diode, a coil, or the like. Therefore, a "resistor" can also be referred to as a "resistance", a "load", a "region having a resistance value", or the like. In contrast, for example, a "resistance", a "load", or a "region having a resistance value" can also be referred to as a "resistor" or the like. The resistance value is, for example, preferably higher than or equal to 1 mΩ and lower than or equal to 10 Ω, more preferably higher than or equal to 5 mΩ and lower than or equal to 5 Ω, further preferably higher than or equal to 10 mΩ and lower than or equal to 1 Ω. Further, for example, it can be higher than or equal to 1 Ω and lower than or equal to 1 x 10 9

[0624] In the case where a wiring is used as a resistor, the resistance value of the resistor is sometimes determined depending on the length of the wiring. Further, a conductive body having a different resistivity from that of a conductive body used as a wiring is sometimes used as a resistor. Alternatively, in the case where a semiconductor is used as a resistor, the resistance value of the resistor is sometimes determined by doping an impurity into the semiconductor.

[0625] In this specification and the like, a "capacitor" can include, for example, a circuit element having a static capacitance value higher than 0 F, a region of a wiring having a static capacitance value higher than 0 F, a parasitic capacitance, or a gate capacitance of a transistor. Therefore, in this specification and the like, a "capacitor" is not limited to a circuit element including a pair of electrodes and a dielectric provided in a manner of being interposed between the electrodes. A "capacitor" includes, for example, a parasitic capacitance generated between a wiring and a wiring or a gate capacitance generated between one of a source and a drain of a transistor and a gate, or the like. Further, for example, a "capacitor", a "parasitic capacitance", or a "gate capacitance" or the like can be referred to as a "capacitance" or the like. In contrast, for example, a "capacitance" or the like can be referred to as a "capacitor", a "parasitic capacitance", or a "gate capacitance" or the like. Further, for example, a "pair of electrodes" of a "capacitor" can be referred to as a "pair of conductive bodies", a "pair of conductive regions", or a "pair of regions" or the like. The static capacitance value is, for example, higher than or equal to 0.05 fF and lower than or equal to 10 pF. Further, for example, it can be higher than or equal to 1 pF and lower than or equal to 10 μF.

[0626] ​Further, in this specification and the like, a transistor includes three terminals called a gate (also referred to as a gate electrode, a gate terminal, a gate region, or a gate electrode), a source (also referred to as a source electrode, a source terminal, a source region, or a source electrode), and a drain (also referred to as a drain electrode, a drain terminal, a drain region, or a drain electrode). Further, a transistor includes a region where a channel is formed between a drain and a source (also referred to as a channel formation region). Current can flow between a source and a drain through the channel formation region in the transistor. Note that the channel formation region is a region where current flows mainly. The gate is a control terminal for controlling the amount of current flowing between the source and the drain through the channel formation region. Two terminals serving as the source or the drain are input and output terminals of the transistor.

[0627] One of the two input and output terminals functions as a source and the other functions as a drain, depending on the conductivity type of the transistor (an n-channel transistor or a p-channel transistor) and the potential levels of the three terminals of the transistor. For example, the function as the source and the function as the drain are switched when the direction of current flow is changed during circuit operation. Thus, in this specification and the like, the "source" and the "drain" can be interchanged with each other. In this specification and the like, in describing the connection relation of a transistor, the phrase "one of a source and a drain" (a first electrode or a first terminal) or "the other of a source and a drain" (a second electrode or a second terminal) is used.

[0628] Further, depending on the structure of the transistor, a back gate is included in some cases in addition to the above three terminals. In that case, in this specification and the like, one of the gate and the back gate of the transistor is referred to as a first gate, and the other is referred to as a second gate. Furthermore, in the same transistor, the "gate" and the "back gate" can be interchanged with each other in some cases. Further, in the case where a transistor includes three or more gates, in this specification and the like, each gate is referred to as a first gate, a second gate, or a third gate, for example, in some cases.

[0629] In this specification and the like, as a transistor, a transistor of a multi-gate structure including two or more gate electrodes can be used. The transistor of the multi-gate structure has a structure in which a plurality of transistors are connected in series because the channel formation region is connected in series. Thus, the transistor of the multi-gate structure can reduce an off-state current and can improve the withstand voltage of the transistor (improve reliability). Alternatively, in the transistor of the multi-gate structure, when the transistor operates in a saturation region, even when the voltage between a drain and a source is changed, the change in current between the drain and the source is small, and thus a voltage-current characteristic with a flat inclination can be obtained. The transistor with a flat inclination of the voltage-current characteristic can realize an ideal current source circuit or an active load with a resistance value extremely high. As a result, the transistor with a flat inclination of the voltage-current characteristic can realize, for example, a differential circuit or a current mirror circuit with good characteristics.

[0630] Further, in this specification and the like, the case where a circuit diagram shows one circuit element includes the case where the circuit element has a plurality of circuit elements. For example, the case where a circuit diagram shows one resistor includes the case where two or more resistors are connected in series. Further, for example, the case where a circuit diagram shows one capacitor includes the case where two or more capacitors are connected in parallel. Further, for example, the case where a circuit diagram shows one transistor includes the case where two or more transistors are connected in series and the gates thereof are connected to each other. Also, for example, the case where a circuit diagram shows one switch includes the case where the switch has two or more transistors, the two or more transistors are connected in series or parallel, and the gates thereof are connected to each other.

[0631] Further, in this specification and the like, a "node" can be referred to as a "terminal", a "wiring", an "electrode", a "conductive layer", a "conductor", or a "dopant region", or the like, for example, in accordance with a circuit configuration or a device configuration, or the like. Further, for example, a "terminal" or a "wiring", or the like, can be referred to as a "node".

[0632] Further, in this specification and the like, "voltage" and "potential" can be appropriately switched. "Voltage" refers to a potential difference from a reference potential. For example, when the reference potential is a ground potential (earth potential), "voltage" can be referred to as "potential". The ground potential does not necessarily mean 0 V. Further, a potential is relative. That is, for example, a potential supplied to a wiring, a potential applied to a circuit, or a potential output from a circuit, or the like, also varies in accordance with a change in a reference potential.

[0633] Further, in this specification and the like, a "high-level potential (also referred to as an "H potential" or "H")" or a "low-level potential (also referred to as an "L potential" or "L")" does not mean a specific potential. For example, in the case where two wirings are both described as "wirings for supplying a high-level potential", the high-level potentials supplie...

Claims

1. A semiconductor device, comprising: A first conductive layer, the first conductive layer including a region serving as one of the source and drain of a first transistor and extending in a first direction; A second conductive layer is located on the first conductive layer and includes a region that serves as the other of the source and drain of the first transistor; A first semiconductor layer, the first semiconductor layer including the channel formation region of the first transistor; A third conductive layer having a shape along the side of the first semiconductor layer, including a region serving as the gate of the first transistor, a region serving as one of the source and drain of a second transistor on the first transistor, and a region in contact with the second conductive layer and extending in a second direction intersecting the first direction; A fourth conductive layer, which is located on the third conductive layer and includes a region that serves as another of the source and drain of the second transistor; A second semiconductor layer, the second semiconductor layer including the channel formation region of the second transistor; as well as A fifth conductive layer, having a shape along the side of the second semiconductor layer, includes a region serving as the gate of the second transistor and a region contacting the fourth conductive layer, and extends in the first direction. In this configuration, one of the first conductive layer and the fifth conductive layer functions as a first power line. The other of the first conductive layer and the fifth conductive layer functions as a second power line supplied with a potential higher than that supplied to the first power line. Furthermore, the third conductive layer functions as a signal line for receiving signals that are at a potential above that of the first power line and at a potential below that of the second power line.

2. The semiconductor device according to claim 1, The channel length of the first transistor is less than the channel width of the first transistor. Furthermore, the channel length of the second transistor is less than the channel width of the second transistor.

3. The semiconductor device according to claim 1, Both the first semiconductor layer and the second semiconductor layer comprise oxide semiconductors.

4. The semiconductor device according to claim 1, The first conductive layer functions as the second power line. Furthermore, the fifth conductive layer has the function of the first power line.

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