Anomaly Detection System

Abstract

To provide an abnormality detection system that outputs an abnormality detection signal before a secondary battery safety valve opens.SOLUTION: An abnormality detection system includes a strain sensor, a memory, and a comparator. The memory has a function of holding an analog potential, and the comparator has a function of comparing the potential output by the strain sensor and the analog potential held by the memory. Before using the secondary battery, the strain sensor is attached to the secondary battery, and a predetermined potential is held in the memory. During use of the secondary battery, when the secondary battery casing expands and the potential output by the strain sensor becomes higher (or lower) than a predetermined potential, an abnormality detection signal is output.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] 1. Field of the Invention The present invention relates to an abnormality detection system for a secondary battery. The abnormality detection system disclosed in this specification and the like is a semiconductor device, and in particular, detects an abnormality in a secondary battery having a safety valve.

[0002] In this specification, the term "semiconductor device" refers to any device that can function by utilizing semiconductor characteristics. For example, a transistor, a semiconductor circuit, an integrated circuit, a chip equipped with an integrated circuit, an electronic component in which a chip is housed in a package, and an electronic device equipped with an integrated circuit are examples of semiconductor devices.

[0003] The technical field of the invention disclosed in this specification relates to an object, a method, or a manufacturing method. Alternatively, one aspect of the present invention relates to a process, a machine, a manufacture, or a composition of matter. [Background technology]

[0004] In recent years, various types of secondary batteries have been actively developed. Among them, lithium-ion secondary batteries, which have high output and high energy density, are used in portable information terminals such as mobile phones, smartphones, tablets, and notebook computers, clean energy automobiles such as hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and electric vehicles (EVs), as well as digital cameras, portable music players, medical equipment, and the like, and have become indispensable as an energy source in modern society.

[0005] In the above-mentioned lithium ion secondary battery, if the temperature inside the battery rises due to an external short circuit, an internal short circuit, overcharging, overdischarging, etc., gas generation due to a chemical reaction of the electrolyte or evaporation of organic matter contained in the electrolyte may occur, and the internal pressure of the battery may increase. If the internal pressure of the lithium ion secondary battery increases and the battery case cannot withstand it, there is a risk of the battery exploding or catching fire, so the lithium ion secondary battery may be provided with a safety valve that is more easily broken than other case members.

[0006] For example, Patent Document 1 discloses a secondary battery in which the process of forming the safety valve is simplified. Patent Document 2 discloses a method for detecting the expansion of a battery housed in a battery housing space.

[0007] Meanwhile, oxide semiconductors have been attracting attention in recent years as semiconductors that can be used as transistors. A transistor using an oxide semiconductor (also referred to as an oxide semiconductor transistor or an OS transistor) has characteristics such as a very low off-state current, the ability to apply a high voltage (also referred to as a potential difference) between a source and a drain (also referred to as a high withstand voltage), and the ability to be formed as a thin film transistor with a stack structure.

[0008] For example, Patent Document 3 discloses a semiconductor device having a plurality of memory cells using OS transistors on a semiconductor substrate on which peripheral circuits such as a driver circuit and a control circuit are formed, and an example in which OS transistors are used in memory cells of a dynamic random access memory (DRAM). By providing memory cells on a semiconductor substrate on which peripheral circuits are formed, the chip area can be reduced, and by using OS transistors in memory cells, stored data can be retained for a long time because the off-current of the OS transistors is very small.

[0009] In addition, oxide semiconductors include not only single-component metal oxides such as indium oxide and zinc oxide, but also multi-component metal oxides. Among multi-component metal oxides, in particular, research on In-Ga-Zn oxide (also known as IGZO) has been actively conducted.

[0010] Research on IGZO has revealed that the oxide semiconductor has a c-axis aligned crystalline (CAAC) structure and a nanocrystalline (nc) structure, which are neither single crystal nor amorphous (see Non-Patent Documents 1 to 3).

[0011] Non-Patent Documents 1 and 2 disclose techniques for manufacturing a transistor using an oxide semiconductor having a CAAC structure. Furthermore, Non-Patent Documents 4 and 5 show that even oxide semiconductors with lower crystallinity than the CAAC structure and the nc structure have small crystals.

[0012] Non-Patent Document 6 reports that a transistor using an oxide semiconductor has an extremely small off-state current, and Non-Patent Documents 7 and 8 report LSIs and displays that utilize the property of an extremely small off-state current. [Prior art documents] [Patent documents]

[0013] [Patent Document 1] JP 2002-8616 A [Patent Document 2] JP 2002-117911 A [Patent Document 3] JP 2012-256820 A [Non-patent literature]

[0014] [Non-Patent Document 1] S. Yamazaki et al., “SID Symposium Digest of Technical Papers”, 2012, volume 43, issue 1, p.183-186 [Non-Patent Document 2] S. Yamazaki et al., “Japanese Journal of Applied Physics”, 2014, volume 53, Number 4S, p.04ED18-1-04ED18-10 [Non-Patent Document 3] S. Ito et al., “The Proceedings of AM-FPD'13 Digest of Technical Papers”, 2013, p.151-154 [Non-Patent Document 4] S. Yamazaki et al., “ECS Journal of Solid State Science and Technology”, 2014, volume 3, issue 9, p. Q3012-Q3022 [Non-Patent Document 5] S. Yamazaki, “ECS Transactions”, 2014, volume 64, issue 10, p.155-164 [Non-Patent Document 6] K. Kato et al., “Japanese Journal of Applied Physics”, 2012, volume 51, p.021201-1-021201-7 [Non-Patent Document 7] S. Matsuda et al., “2015 Symposium on VLSI Technology Digest of Technical Papers”, 2015, p.T216-T217 [Non-Patent Document 8] S. Amano et al., “SID Symposium Digest of Technical Papers”, 2010, volume 41, issue 1, p.626-629 Summary of the Invention [Problem to be solved by the invention]

[0015] The safety valve of a lithium-ion secondary battery is made to be more fragile (fragile) than other casing components, but if the internal pressure becomes high enough to open the safety valve, the pressure may be released explosively. In addition, the electrolyte may leak out. Therefore, a battery with an open safety valve cannot be used, and may distort the battery and electronic devices equipped with the battery. In addition, the electrolyte may contaminate the battery and electronic devices equipped with the battery.

[0016] The present invention aims to prevent dangers caused by an increase in internal pressure of a secondary battery, in other words, to detect an increase in internal pressure in a secondary battery having a safety valve before the safety valve opens.

[0017] An object of one embodiment of the present invention is to provide an anomaly detection system that detects an increase in internal pressure in a secondary battery having a safety valve before the safety valve opens and outputs an anomaly detection signal (also referred to as an anomaly detection signal). Another object of one embodiment of the present invention is to provide an anomaly detection system that consumes low power.

[0018] It is not necessary for one embodiment of the present invention to solve all of the above problems, but it is sufficient if it can solve at least one of the problems. Furthermore, the description of the above problems does not preclude the existence of other problems. Problems other than these will become apparent from the description of the specification, claims, drawings, etc., and it is possible to extract other problems from the description of the specification, claims, drawings, etc. [Means for solving the problem]

[0019] One aspect of the present invention is an anomaly detection system having a strain sensor, a memory, and a comparator. The memory has a function of holding an analog potential, and the comparator has a function of comparing a first potential output by the strain sensor with a second potential held in the memory. The anomaly detection system has a function of performing an initialization operation to hold in the memory a second potential higher than the first potential, and outputs an anomaly detection signal when the first potential becomes higher than the second potential.

[0020] Another aspect of the present invention is an anomaly detection system having a strain sensor, a memory, and a comparator. The memory has a function of holding an analog potential, and the comparator has a function of comparing a first potential output by the strain sensor with a second potential held in the memory. The anomaly detection system has a function of performing an initialization operation to hold in the memory a second potential lower than the first potential, and outputs an anomaly detection signal when the first potential becomes lower than the second potential.

[0021] Another aspect of the present invention is an anomaly detection system having a strain sensor, a memory, and a comparator. The strain sensor has a resistive element and a strain sensor element, and the strain sensor element is attached to a secondary battery. The memory has a function of holding an analog potential, and the comparator has a function of comparing a first potential output by the strain sensor with a second potential held in the memory. The anomaly detection system has a function of performing an initialization operation to hold in the memory a second potential higher than the first potential, and outputs an anomaly detection signal when the first potential becomes higher than the second potential.

[0022] Another aspect of the present invention is an anomaly detection system having a strain sensor, a memory, and a comparator. The strain sensor has a resistive element and a strain sensor element, and the strain sensor element is attached to a secondary battery. The memory has a function of holding an analog potential, and the comparator has a function of comparing a first potential output by the strain sensor with a second potential held in the memory. The anomaly detection system has a function of performing an initialization operation to hold in the memory a second potential lower than the first potential, and outputs an anomaly detection signal when the first potential becomes lower than the second potential.

[0023] Another aspect of the present invention is an anomaly detection system having a strain sensor, a memory, a comparator, an oscillation circuit, and a counter circuit. The memory has a function of holding an analog potential, and the comparator has a function of comparing a first potential output by the strain sensor with a second potential held in the memory. The anomaly detection system has a function of performing an initialization operation to hold in the memory a second potential higher than the first potential, and when the first potential becomes higher than the second potential, the oscillation circuit generates an AC signal. The counter circuit has a function of counting the number of oscillations of the AC signal, and outputs an anomaly detection signal when the number of oscillations reaches a predetermined number.

[0024] Another aspect of the present invention is an anomaly detection system having a strain sensor, a memory, a comparator, an oscillation circuit, and a counter circuit. The memory has a function of holding an analog potential, and the comparator has a function of comparing a first potential output by the strain sensor with a second potential held in the memory. The anomaly detection system has a function of performing an initialization operation to hold in the memory a second potential lower than the first potential, and when the first potential becomes lower than the second potential, the oscillation circuit generates an AC signal. The counter circuit has a function of counting the number of oscillations of the AC signal, and outputs an anomaly detection signal when the number of oscillations reaches a predetermined number.

[0025] Also, one aspect of the present invention is an anomaly detection system having a strain sensor, a memory, a comparator, an oscillation circuit, and a counter circuit. The strain sensor has a resistive element and a strain sensor element, and the strain sensor element is attached to a secondary battery. The memory has a function of holding an analog potential, and the comparator has a function of comparing a first potential output by the strain sensor with a second potential held in the memory. The anomaly detection system has a function of performing an initialization operation to hold in the memory a second potential higher than the first potential, and when the first potential becomes higher than the second potential, the oscillation circuit generates an AC signal. The counter circuit has a function of counting the number of oscillations of the AC signal, and outputs an anomaly detection signal when the number of oscillations reaches a predetermined number.

[0026] Also, one aspect of the present invention is an anomaly detection system having a strain sensor, a memory, a comparator, an oscillation circuit, and a counter circuit. The strain sensor has a resistive element and a strain sensor element, and the strain sensor element is attached to a secondary battery. The memory has a function of holding an analog potential, and the comparator has a function of comparing a first potential output by the strain sensor with a second potential held in the memory. The anomaly detection system has a function of performing an initialization operation to hold in the memory a second potential lower than the first potential, and when the first potential becomes lower than the second potential, the oscillation circuit generates an AC signal. The counter circuit has a function of counting the number of oscillations of the AC signal, and outputs an anomaly detection signal when the number of oscillations reaches a predetermined number.

[0027] In the above embodiment, the memory includes a transistor and a capacitor, and the transistor includes a metal oxide in a channel formation region. Effect of the Invention

[0028] According to one embodiment of the present invention, it is possible to provide an anomaly detection system that detects an increase in internal pressure in a secondary battery having a safety valve before the safety valve opens and outputs an anomaly detection signal. Alternatively, according to one embodiment of the present invention, it is possible to provide an anomaly detection system with low power consumption.

[0029] Note that the description of these effects does not preclude the existence of other effects. Also, one embodiment of the present invention does not necessarily have to have all of these effects. Effects other than these will become apparent from the description in the specification, claims, drawings, etc., and it is possible to extract effects other than these from the description in the specification, claims, drawings, etc. [Brief description of the drawings]

[0030] [Figure 1] 1(A) and (B) are block diagrams showing an example of the configuration of an anomaly detection system. [Diagram 2]2A and 2B are timing charts illustrating an example of the operation of the anomaly detection system, and FIG. 2C is a top view showing an example of the configuration of a strain sensor element. [Diagram 3] FIG. 3A is a diagram for explaining a configuration example of a cylindrical secondary battery, and FIG. 3B is a diagram for explaining a configuration example of a prismatic secondary battery. [Figure 4] FIG. 4(A) is a diagram for explaining an example of the configuration of a wound body, and FIG. 4(B) is a schematic diagram showing a square secondary battery to which a strain sensor element is attached. [Diagram 5] FIG. 5 is a cross-sectional view showing a configuration example of a semiconductor device. [Figure 6] 6A, 6B, and 6C are cross-sectional views showing examples of the structure of a transistor. [Figure 7] 7A is a top view illustrating an example of a transistor structure, and FIGS. 7B and 7C are cross-sectional views illustrating the example of a transistor structure. [Figure 8] FIG. 8A is a top view illustrating an example of a structure of a transistor, and FIGS. 8B and 8C are cross-sectional views illustrating the example of a structure of a transistor. [Figure 9] 9A is a top view illustrating an example of a transistor structure, and FIGS. 9B and 9C are cross-sectional views illustrating the example of a transistor structure. [Figure 10] FIG. 10A is a top view illustrating an example of a structure of a transistor, and FIGS. 10B and 10C are cross-sectional views illustrating the example of a structure of a transistor. [Figure 11] FIG. 11A is a top view illustrating an example of a structure of a transistor, and FIGS. 11B and 11C are cross-sectional views illustrating the example of a structure of a transistor. [Figure 12] 12A is a top view illustrating an example of a structure of a transistor, and FIG. 12B is a perspective view illustrating the example of a structure of a transistor. [Figure 13] 13A and 13B are cross-sectional views illustrating examples of the structure of a transistor. [Figure 14] 14A, 14B, 14C, and 14D are diagrams showing an example of an electronic device. [Figure 15] FIG. 15 is a diagram illustrating an example of an electronic device. [Figure 16] 16(A) and (B) are diagrams showing an example of an electronic device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] Hereinafter, the embodiments will be described with reference to the drawings. However, it will be easily understood by those skilled in the art that the embodiments can be implemented in many different forms, and that the forms and details can be modified in various ways without departing from the spirit and scope of the present invention. Therefore, the present invention should not be interpreted as being limited to the description of the following embodiments.

[0032] In addition, the following embodiments may be combined as appropriate. In addition, when one embodiment includes multiple configuration examples, the configuration examples may be combined as appropriate.

[0033] In addition, in the drawings attached to this specification, the components are classified by function and shown in block diagrams as independent blocks, but in reality it is difficult to completely separate the components by function, and one component may be involved in multiple functions.

[0034] In addition, in the drawings, etc., the size, layer thickness, area, etc. may be exaggerated for clarity. Therefore, the scale is not necessarily limited. The drawings are schematic illustrations of ideal examples, and are not limited to the shapes or values ​​shown in the drawings.

[0035] In addition, in the drawings, the same symbols may be used for the same elements or elements having similar functions, elements made of the same material, or elements formed at the same time, and repeated explanations may be omitted.

[0036] In addition, in this specification and the like, the term "film" and the term "layer" can be interchanged. For example, the term "conductive layer" may be changed to the term "conductive film." Or, for example, the term "insulating film" may be changed to the term "insulating layer."

[0037] In addition, in this specification and the like, terms indicating an arrangement such as "above" or "below" do not limit the positional relationship of components to "directly above" or "directly below." For example, the expression "a gate electrode on a gate insulating layer" does not exclude other components between the gate insulating layer and the gate electrode.

[0038] In addition, in this specification, ordinal numbers such as "first," "second," and "third" are used to avoid confusion of components and do not limit the numbers.

[0039] In addition, in this specification, "electrically connected" includes a case where a connection is made via "something having some electrical action." Here, "something having some electrical action" is not particularly limited as long as it enables transmission and reception of an electrical signal between the objects to be connected. For example, "something having some electrical action" includes electrodes and wiring, as well as switching elements such as transistors, resistive elements, inductors, capacitive elements, and other elements having various functions.

[0040] In this specification and the like, the term "voltage" often refers to the potential difference between a certain potential and a reference potential (for example, the ground potential). Therefore, the terms "voltage" and "potential difference" can be used interchangeably.

[0041] In this specification, a transistor is an element having at least three terminals including a gate, a drain, and a source. A channel-forming region is formed between the drain (drain terminal, drain region, or drain electrode) and the source (source terminal, source region, or source electrode), and a current can flow between the source and the drain through the channel-forming region. In this specification, a channel-forming region refers to a region through which a current mainly flows.

[0042] In addition, the functions of the source and drain may be interchanged when transistors of different polarities are used, when the direction of current changes during circuit operation, etc. For this reason, the terms source and drain may be used interchangeably in this specification and the like.

[0043] In this specification and the like, unless otherwise specified, the off-current refers to the drain current when a transistor is in a non-conducting state (also referred to as an off state or a cut-off state). Unless otherwise specified, the non-conducting state refers to a state in which the voltage Vgs of the gate relative to the source is lower than the threshold voltage Vth in an n-channel transistor, and a state in which the voltage Vgs of the gate relative to the source is higher than the threshold voltage Vth in a p-channel transistor. In other words, the off-current of an n-channel transistor may be referred to as the drain current when the voltage Vgs of the gate relative to the source is lower than the threshold voltage Vth.

[0044] In the above description of off-state current, the drain may be read as the source. In other words, the off-state current may refer to the source current when the transistor is in a non-conducting state. The off-state current may also be referred to as leakage current, which has the same meaning as the off-state current. In this specification and the like, the off-state current may also refer to the current that flows between the source and drain when the transistor is in a non-conducting state.

[0045] In this specification and the like, the term "metal oxide" refers to an oxide of a metal in a broad sense. Metal oxides are classified into oxide insulators, oxide conductors (including transparent oxide conductors), oxide semiconductors (also called oxide semiconductors), and the like.

[0046] For example, when a metal oxide is used in a channel formation region of a transistor, the metal oxide may be called an oxide semiconductor. In other words, when a metal oxide has at least one of an amplifying function, a rectifying function, and a switching function, the metal oxide can be called a metal oxide semiconductor. In other words, a transistor having a metal oxide in a channel formation region can be called an "oxide semiconductor transistor" or an "OS transistor". Similarly, the above-mentioned "transistor using an oxide semiconductor" is also a transistor having a metal oxide in a channel formation region.

[0047] In this specification and the like, a metal oxide having nitrogen may also be called a metal oxide. A metal oxide having nitrogen may also be called a metal oxynitride. Details of metal oxides will be described later.

[0048] (Embodiment 1) In this embodiment, a configuration example of an anomaly detection system according to an embodiment of the present invention will be described. The anomaly detection system according to an embodiment of the present invention is a system that functions by utilizing semiconductor characteristics, and in particular, detects an anomaly in a secondary battery having a safety valve.

[0049] <Example of anomaly detection system configuration> 1(A) is a block diagram showing an example of the configuration of an anomaly detection system 100. The anomaly detection system 100 includes a strain sensor 30, a memory 40, and a comparator 50.

[0050] The anomaly detection system 100 also includes a line VDD, a line VSS, and an output terminal OUT. A high power supply potential Vd is supplied to the line VDD, and a low power supply potential Vs is supplied to the line VSS. Here, the high power supply potential Vd is a potential higher than the low power supply potential Vs.

[0051] The comparator 50 has a non-inverting input terminal (indicated as "+" in FIG. 1(A)), an inverting input terminal (indicated as "-" in FIG. 1(A)), and an output terminal, and has the function of comparing the potential input to the non-inverting input terminal with the potential input to the inverting input terminal.

[0052] Specifically, when the potential input to the non-inverting input terminal is higher than the potential input to the inverting input terminal, the maximum potential is output from the output terminal, and when the potential input to the non-inverting input terminal is lower than the potential input to the inverting input terminal, the minimum potential is output from the output terminal. Note that in this embodiment, the comparator 50 operates using the potential difference between the high power supply potential Vd and the low power supply potential Vs, where the maximum potential is the high power supply potential Vd and the minimum potential is the low power supply potential Vs.

[0053] The strain sensor 30 has a resistor element R11 and a strain sensor element R12. A first terminal of the resistor element R11 is electrically connected to a wiring VDD, and a second terminal of the resistor element R11 is electrically connected to a first terminal of the strain sensor element R12 and a non-inverting input terminal of the comparator 50. A second terminal of the strain sensor element R12 is electrically connected to a wiring VSS.

[0054] The memory 40 includes a capacitor C11 and a transistor T11. One of a source or a drain of the transistor T11 is electrically connected to a wiring DL, a gate of the transistor T11 is electrically connected to a wiring WL, and the other of the source or the drain of the transistor T11 is electrically connected to a first terminal of the capacitor C11 and an inverting input terminal of the comparator 50. A second terminal of the capacitor C11 is electrically connected to a wiring CAL. The wiring CAL is a wiring to which a predetermined potential Vc is supplied.

[0055] Here, the node electrically connected to the second terminal of the resistive element R11, the first terminal of the strain sensor element R12, and the non-inverting input terminal of the comparator 50 is referred to as node N11, and the node electrically connected to the other of the source or drain of the transistor T11, the first terminal of the capacitive element C11, and the inverting input terminal of the comparator 50 is referred to as node N12. The comparator 50 has the function of comparing the potential of the node N11 with the potential of the node N12.

[0056] That is, when the potential of the node N11 is higher than the potential of the node N12, the comparator 50 outputs a high power supply potential Vd from the output terminal, and when the potential of the node N11 is lower than the potential of the node N12, the comparator 50 outputs a low power supply potential Vs from the output terminal. The output terminal of the comparator 50 is electrically connected to the output terminal OUT of the anomaly detection system 100.

[0057] The anomaly detection system 100 may further include an oscillator circuit 60 and a circuit 70. FIG.

[0058] The anomaly detection system 110 is a system in which an oscillator circuit 60 and a circuit 70 are added to the anomaly detection system 100. In the anomaly detection system 110, the output terminal of the comparator 50 is electrically connected to the input terminal of the oscillator circuit 60, the output terminal of the oscillator circuit 60 is electrically connected to the input terminal of the circuit 70, and the output terminal of the circuit 70 is electrically connected to the output terminal OUT of the anomaly detection system 110. In the anomaly detection system 110, the connection relationship between the strain sensor 30, the memory 40, and the comparator 50 is similar to that of the anomaly detection system 100, and therefore a description thereof will be omitted. In addition, a node to which the output terminal of the oscillator circuit 60 and the input terminal of the circuit 70 are electrically connected is referred to as a node N13.

[0059] The oscillator circuit 60 starts oscillating and outputs an AC signal when the comparator 50 outputs the high power supply potential Vd. Moreover, the oscillator circuit 60 stops oscillating and outputs a constant potential (for example, the low power supply potential Vs) when the comparator 50 outputs the low power supply potential Vs.

[0060] The circuit 70 is a circuit composed of a counter and a decoder. The circuit 70 counts the number of oscillations of the AC signal output by the oscillation circuit 60, and has a function of outputting a high power supply potential Vd when the number of oscillations reaches a predetermined number. Until the number of oscillations reaches the predetermined number, the circuit 70 outputs a low power supply potential Vs. Furthermore, when the oscillation circuit 60 stops oscillating, the circuit 70 outputs the low power supply potential Vs and resets the counter.

[0061] <Timing chart> FIG. 2A is a timing chart illustrating an example of the operation of the anomaly detection system 100, and FIG. 2B is a timing chart illustrating an example of the operation of the anomaly detection system 110.

[0062] 2(A) and 2(B), the horizontal axis represents time, and T1 to T4 represent periods. In FIG. 2(A) and 2(B), the vertical axis represents potential, with VN11 representing the potential of node N11, VN12 representing the potential of node N12, and VN13 representing the potential of node N13. Note that VN12 is shown by a dotted line to distinguish it from VN11. In FIG. 2(A), VOUT represents the potential of the output terminal OUT in the anomaly detection system 100, and in FIG. 2(B), VOUT represents the potential of the output terminal OUT in the anomaly detection system 110.

[0063] 2A, a potential higher than that of node N11 is held at node N12 (initialization operation is performed), and then VN12 is a constant value from period T1 to period T4. In periods T1 and T3, VN11 is a smaller value than VN12, and in periods T2 and T4, VN11 is a larger value than VN12. That is, VOUT is a low power supply potential Vs in periods T1 and T3 in FIG. 2A, and VOUT is a high power supply potential Vd in periods T2 and T4.

[0064] In period T1 in FIG. 2B, a potential higher than that of node N11 is held at node N12 (initialization operation is performed), and thereafter, VN12 has a constant value in periods T1 to T4. In periods T1 and T3, VN11 has a smaller value than VN12, and in periods T2 and T4, VN11 has a larger value than VN12. In periods T1 and T3 in FIG. 2B, VN13 is at low power supply potential Vs, and in periods T2 and T4, VN13 oscillates. That is, in periods T2 and T4, VN13 goes back and forth between low power supply potential Vs and high power supply potential Vd.

[0065] Here, VOUT becomes the high power supply potential Vd when VN13 goes back and forth between the low power supply potential Vs and the high power supply potential Vd a predetermined number of times or more. VOUT is at the low power supply potential Vs until the predetermined number of times is reached. For example, in FIG. 2B, the predetermined number of times can be set to 4.

[0066] In period T1 in FIG. 2B, VOUT is at the low power supply potential Vs. In period T2, VN13 oscillates, but does not reach a predetermined number of times, so VOUT remains at the low power supply potential Vs. In period T3, VN13 does not oscillate, so VOUT remains at the low power supply potential Vs, and the number of times counted in period T2 is reset. That is, VOUT remains at the low power supply potential Vs in periods T1 to T3 in FIG. 2B.

[0067] 2B, VN13 oscillates a predetermined number of times, and VOUT becomes the high power supply potential Vd halfway through the period T4. When the period T4 ends, VN13 stops oscillating, and VOUT becomes the low power supply potential Vs.

[0068] This makes it possible to prevent VOUT from changing from the low power supply potential Vs to the high power supply potential Vd even if VN11 temporarily becomes a value larger than VN12 due to noise, etc. For example, when an electronic device using the anomaly detection system 110 is dropped, it is possible to prevent the anomaly detection system 110 from malfunctioning.

[0069] <Example of strain sensor configuration> As shown in FIGS. 1(A) and 1(B), the strain sensor 30 can be configured by connecting a resistor element R11 and a strain sensor element R12 in series.

[0070] The strain sensor element R12 is a variable resistance element whose resistance value changes depending on the applied strain. Typically, a metal thin film resistance element can be used for the strain sensor element R12. The metal thin film resistance element has a property that, for example, the resistance value increases when a tensile force is applied to the metal thin film, and the resistance value decreases when a compressive force is applied to the metal thin film. By the change in the resistance value of the metal thin film resistance element, it is possible to detect the strain in the vicinity of the area where the metal thin film resistance element is arranged.

[0071] Fig. 2(C) is a top view showing a configuration example of the strain sensor element R12. The strain sensor element R12 can mainly detect strain in the direction of the arrow shown in Fig. 2(C). Note that a plurality of strain sensor elements R12 may be arranged according to the direction in which the strain can be detected.

[0072] In addition, a semiconductor element may be used for the strain sensor element R12. Alternatively, a piezoelectric element may be used for the strain sensor element R12. For example, an element having a piezoelectric material such as barium titanate, lead zirconate titanate, or zinc oxide may be used as the piezoelectric element.

[0073] <Memory configuration example> As shown in FIGS. 1A and 1B, the memory 40 can be configured using a capacitive element C11 and a transistor T11.

[0074] The memory 40 has a function of accumulating and holding charge at the node N12. The memory 40 can hold an analog potential at the node N12. For this reason, it is preferable that the off-state current of the transistor T11 be small. For example, an OS transistor can be used as the transistor T11.

[0075] Since the band gap of an oxide semiconductor is 2.5 eV or more, preferably 3.0 eV or more, the OS transistor has characteristics of small leakage current due to thermal excitation and very small off-state current.

[0076] The metal oxide used for the channel formation region of the OS transistor is preferably an oxide semiconductor containing at least one of indium (In) and zinc (Zn). A typical example of such an oxide semiconductor is In-M-Zn oxide (wherein element M is, for example, Al, Ga, Y, or Sn). By reducing impurities such as moisture and hydrogen that serve as electron donors (donors) and also reducing oxygen vacancies, the oxide semiconductor can be made to be i-type (intrinsic) or substantially i-type. Such an oxide semiconductor can be called a highly purified oxide semiconductor. Details of the OS transistor will be described in embodiment 4.

[0077] An OS transistor has a very small off-state current and is therefore suitable for use as the transistor T11. For example, the off-state current per 1 μm of channel width of the OS transistor can be 100 zA / μm or less, 10 zA / μm or less, 1 zA / μm or less, or 10 yA / μm or less. By using an OS transistor for the transistor T11, the memory 40 can hold an analog potential for a long period of time.

[0078] Alternatively, a transistor other than an OS transistor that has a low off-state current may be used as the transistor T11. For example, a transistor that has a wide band gap semiconductor in a channel formation region may be used. A wide band gap semiconductor may refer to a semiconductor with a band gap of 2.2 eV or more, such as silicon carbide, gallium nitride, or diamond.

[0079] The transistor T11 functions as a switch that brings the node N12 and the wiring DL into conduction or non-conduction. An analog potential is written to the node N12 by applying a high-level potential to the wiring WL to bring the transistor T11 into conduction. Specifically, when the transistor T11 is in conduction, an analog potential to be written is applied to the wiring DL, and the potential is written to the node N12. Thereafter, a low-level potential is applied to the wiring WL to bring the transistor T11 into a non-conduction state, thereby holding the potential of the node N12. Note that in this embodiment, for example, the high-level potential can be a high power supply potential Vd, and the low-level potential can be a low power supply potential Vs.

[0080] The potential held at node N12 is input as VN12 to the inverting input terminal of the comparator 50, and is compared with VN11 input to the non-inverting input terminal of the comparator 50.

[0081] <Examples of use of anomaly detection system> 1(A) and 1(B), the resistor element R11 and the strain sensor element R12 connected in series are electrically connected to the wiring VDD and the wiring VSS as the strain sensor 30. That is, the potential difference between the high power supply potential Vd and the low power supply potential Vs is divided by the resistor element R11 and the strain sensor element R12, and the potential (VN11) of the node N11 becomes a potential between the high power supply potential Vd and the low power supply potential Vs. VN11 is the potential that the strain sensor 30 outputs to the comparator 50.

[0082] The strain sensor 30 (or the strain sensor element R12) is attached to the housing of a secondary battery before use (or in the initial state of use). Then, a potential slightly higher than VN11 obtained at this time is stored as VN12 in the memory 40. The comparator 50 outputs the low power supply potential Vs because VN11 is lower than VN12.

[0083] As the secondary battery is used, the internal pressure of the battery may increase. In this case, the housing of the secondary battery expands, and a tensile force is applied to the strain sensor 30 (or the strain sensor element R12) attached to the housing of the secondary battery. When a tensile force is applied to the strain sensor element R12, the resistance value increases, and VN11 increases. When VN11 increases and becomes higher than VN12, the comparator 50 outputs the high power supply potential Vd.

[0084] The series connection of the resistor element R11 and the strain sensor element R12 may be replaced with the resistor element R11 and the strain sensor element R12. That is, the resistor element R11 may be electrically connected to the wiring VSS, and the strain sensor element R12 may be electrically connected to the wiring VDD. In this case, a potential slightly lower than VN11 is held in the memory 40 as VN12, and when the housing of the secondary battery expands, VN11 becomes lower than VN12. In addition, since the output of the comparator 50 is also reversed, the non-inverting input terminal and the inverting input terminal of the comparator 50 may be replaced.

[0085] In this way, the anomaly detection system 100 (or the anomaly detection system 110) can output an anomaly detection signal when the housing of the secondary battery expands. Note that it is desirable to attach the strain sensor 30 (or the strain sensor element R12) to a location that is subject to large deformation when the housing of the secondary battery expands. For example, as described in the second embodiment, this would be around the safety valve in the case of a cylindrical secondary battery, or a surface with a large area in the case of a prismatic secondary battery.

[0086] <Other> The comparator 50, the oscillator circuit 60, and the circuit 70 may be configured using OS transistors, or may be configured using transistors formed on a semiconductor substrate. The semiconductor substrate is not particularly limited as long as it is possible to form a channel region of the transistor. For example, a single crystal silicon substrate, a single crystal germanium substrate, a compound semiconductor substrate (such as a SiC substrate or a GaN substrate), or a silicon on insulator (SOI) substrate may be used.

[0087] The SOI substrate may be a SIMOX (Separation by Implanted Oxygen) substrate formed by implanting oxygen ions into a mirror-polished wafer and then heating at high temperature to form an oxide layer at a certain depth from the surface and eliminate defects in the surface layer, or an SOI substrate formed using the Smart Cut method, ELTRAN (registered trademark: Epitaxial Layer Transfer) method, etc., which cleaves a semiconductor substrate by utilizing the growth by heat treatment of microvoids formed by hydrogen ion implantation. A transistor formed using a single crystal substrate has a single crystal semiconductor in the channel formation region.

[0088] In addition, the OS transistor is a thin film transistor, and can be stacked above a transistor formed on a semiconductor substrate. For example, the comparator 50, the oscillator circuit 60, and the circuit 70 can be configured using transistors formed on a semiconductor substrate, and an OS transistor can be used for the transistor T11 in the memory 40, and the transistor T11 can be stacked above the transistor formed on the semiconductor substrate, thereby reducing the chip area of ​​the anomaly detection system.

[0089] Alternatively, the comparator 50, the oscillator circuit 60, and the circuit 70 may be configured using a transistor formed on a semiconductor substrate and an OS transistor. By stacking the OS transistor above the transistor formed on the semiconductor substrate, the chip area of ​​the anomaly detection system can be reduced, and since the OS transistor has a very small off-state current, the anomaly detection system can be a system with low power consumption. A semiconductor device in which an OS transistor is stacked above a transistor formed on a semiconductor substrate will be described in embodiment 3.

[0090] Alternatively, the transistor T11 included in the comparator 50, the oscillator circuit 60, the circuit 70, and the memory 40 may be configured using an OS transistor. In this case, by forming the OS transistor above a semiconductor substrate, the semiconductor substrate can be used as the strain sensor element R12. For example, a single crystal silicon substrate or a single crystal germanium substrate can be used as the semiconductor substrate.

[0091] Note that this embodiment mode can be implemented in appropriate combination with other embodiment modes described in this specification.

[0092] (Embodiment 2) In this embodiment, a configuration example of a secondary battery in which the anomaly detection system described in the above embodiment detects an anomaly will be described.

[0093] FIG. 3A is a diagram illustrating an example of the configuration of a cylindrical secondary battery 200. As shown in FIG.

[0094] 3(A), a cylindrical secondary battery 200 has a positive electrode cap (battery lid) 201 on the top surface, and a battery can (external can) 202 on the side and bottom surfaces. The positive electrode cap and the battery can (external can) 202 are insulated by a gasket (insulating packing) 210.

[0095] A battery element is provided inside a hollow cylindrical battery can 202, in which a strip-shaped positive electrode 204 and a negative electrode 206 are wound with a separator 205 sandwiched therebetween. Although not shown, the battery element is wound around a center pin.

[0096] Battery can 202 has one end closed and the other end open. Metals such as nickel, aluminum, titanium, etc., which are resistant to corrosion by the electrolyte, or alloys of these metals or alloys of these metals with other metals (e.g., stainless steel, etc.) can be used for battery can 202. In addition, it is preferable to coat the battery can with nickel, aluminum, etc. to prevent corrosion by the electrolyte.

[0097] Inside the battery can 202, a battery element formed by winding a positive electrode, a negative electrode, and a separator is sandwiched between a pair of opposing insulating plates 208, 209. A nonaqueous electrolyte (not shown) is poured into the inside of the battery can 202 in which the battery element is provided. The nonaqueous electrolyte may be the same as that used in a coin-type secondary battery.

[0098] Since the positive and negative electrodes used in a cylindrical secondary battery are wound, it is preferable to form active materials on both sides of the current collector. A positive electrode terminal (positive electrode current collector lead) 203 is connected to the positive electrode 204, and a negative electrode terminal (negative electrode current collector lead) 207 is connected to the negative electrode 206. Both the positive electrode terminal 203 and the negative electrode terminal 207 can be made of a metal material such as aluminum. The positive electrode terminal 203 is resistance-welded to the safety valve 212, and the negative electrode terminal 207 is resistance-welded to the bottom of the battery can 202.

[0099] The safety valve 212 is electrically connected to the positive electrode cap 201 via a PTC element (Positive Temperature Coefficient) 211. The safety valve 212 has a function of opening to release the internal pressure of the battery to the outside when the internal pressure of the battery increases and exceeds a predetermined threshold. Since the safety valve 212 is made weaker than other housing members of the secondary battery 200, it is subject to large deformation when the internal pressure of the battery increases. For example, it is desirable that the strain sensor 30 (or the strain sensor element R12) of the anomaly detection system 100 (or the anomaly detection system 110) described in the above embodiment is attached near the safety valve 212.

[0100] The PTC element 211 is a thermal resistance element whose resistance increases when the temperature rises, and the increase in resistance limits the amount of current to prevent abnormal heat generation. Barium titanate (BaTiO3)-based semiconductor ceramics and the like can be used for the PTC element.

[0101] FIG. 3B is a diagram illustrating an example of the configuration of a square secondary battery 900.

[0102] 3B, the square secondary battery 900 has a wound body 950 provided with terminals 951 and 952 inside a housing 930a and a housing 930b (hereinafter, the housings 930a and 930b are collectively referred to as the housing 930). The wound body 950 is impregnated with an electrolyte inside the housing 930. The terminal 952 contacts the housing 930, and the terminal 951 does not contact the housing 930 by using an insulating material or the like.

[0103] 3B, for convenience, the housing 930a and the housing 930b are separately illustrated, but in reality, the wound body 950 is covered by the housing 930, and the terminals 951 and 952 extend outside the housing 930. The housing 930 can be made of a metal material (for example, aluminum, etc.), a resin material, or the like.

[0104] 4A shows an example of the configuration of the wound body 950. The wound body 950 has a negative electrode 931, a positive electrode 932, and a separator 933. The wound body 950 is a wound body in which the negative electrode 931 and the positive electrode 932 are stacked on top of each other with the separator 933 in between, and the laminated sheet is wound. Note that the stack of the negative electrode 931, the positive electrode 932, and the separator 933 may be stacked a plurality of times.

[0105] In the case of a square secondary battery 900, the safety valve 912 is provided, for example, on a surface having a large area of ​​the housing 930. A schematic diagram of the square secondary battery 900 to which the strain sensor element R12 is attached is shown in Fig. 4(B). Note that the housing 930a is omitted in Fig. 4(B).

[0106] The safety valve 912 is made weaker than other parts of the housing 930, and has the function of safely releasing the internal pressure of the battery to the outside when the internal pressure of the battery increases. Therefore, the area around the safety valve 912 is greatly deformed when the internal pressure of the battery increases. It is desirable that the strain sensor 30 (or the strain sensor element R12) of the anomaly detection system 100 (or the anomaly detection system 110) described in the above embodiment be attached near the safety valve 912.

[0107] Note that this embodiment mode can be implemented in appropriate combination with other embodiment modes described in this specification.

[0108] (Embodiment 3) In this embodiment mode, a structural example of a semiconductor device in which an OS transistor is stacked above a transistor formed over a semiconductor substrate will be described.

[0109] FIG. 5 shows a cross-sectional view of a transistor 300 formed over a semiconductor substrate and a transistor 500 as an OS transistor stacked over a semiconductor substrate.

[0110] <Example of semiconductor device configuration> 5 includes a transistor 300, a transistor 500, and a capacitor 600. Fig. 6A is a cross-sectional view of the transistor 500 in the channel length direction, Fig. 6B is a cross-sectional view of the transistor 500 in the channel width direction, and Fig. 6C is a cross-sectional view of the transistor 300 in the channel width direction.

[0111] In the semiconductor device shown in FIG. 5, the transistor 500 is provided above the transistor 300, and the capacitor 600 is provided above the transistors 300 and 500.

[0112] The transistor 300 is formed on a substrate 311 and has a conductor 316, an insulator 315, a semiconductor region 313 formed of a part of the substrate 311, and a low resistance region 314a and a low resistance region 314b functioning as a source region or a drain region.

[0113] 6C, the upper surface and the side surface in the channel width direction of the semiconductor region 313 of the transistor 300 are covered with a conductor 316 via an insulator 315. By forming the transistor 300 as a fin type in this manner, the effective channel width is increased, thereby improving the on-characteristics of the transistor 300. In addition, the contribution of the electric field of the gate electrode can be increased, thereby improving the off-characteristics of the transistor 300.

[0114] The transistor 300 may be either a p-channel type or an n-channel type.

[0115] The region where the channel of the semiconductor region 313 is formed, the region nearby, the low resistance region 314a which becomes the source region or the drain region, and the low resistance region 314b preferably contain a semiconductor such as a silicon-based semiconductor, and preferably contain single crystal silicon. Alternatively, they may be formed of a material containing Ge (germanium), SiGe (silicon germanium), GaAs (gallium arsenide), GaAlAs (gallium aluminum arsenide), or the like. A configuration using silicon in which the effective mass is controlled by applying stress to the crystal lattice and changing the lattice spacing may be used. Alternatively, the transistor 300 may be a HEMT (High Electron Mobility Transistor) by using GaAs and GaAlAs, or the like.

[0116] Low resistance region 314a and low resistance region 314b contain, in addition to the semiconductor material applied to semiconductor region 313, an element that imparts n-type conductivity, such as arsenic or phosphorus, or an element that imparts p-type conductivity, such as boron.

[0117] The conductor 316 functioning as the gate electrode can be made of a conductive material such as a semiconductor material, such as silicon, containing an element that imparts n-type conductivity, such as arsenic or phosphorus, or an element that imparts p-type conductivity, such as boron, a metal material, an alloy material, or a metal oxide material.

[0118] Since the work function is determined by the material of the conductor, the Vth of the transistor can be adjusted by changing the material of the conductor. Specifically, it is preferable to use materials such as titanium nitride and tantalum nitride for the conductor. Furthermore, in order to achieve both electrical conductivity and embeddability, it is preferable to use metal materials such as tungsten and aluminum as a laminate for the conductor, and in particular, it is preferable to use tungsten in terms of heat resistance.

[0119] Note that the transistor 300 illustrated in FIG. 5 is just an example, and the present invention is not limited to this structure. An appropriate transistor may be used depending on the circuit configuration and driving method.

[0120] An insulator 320, an insulator 322, an insulator 324, and an insulator 326 are stacked in this order over the transistor 300.

[0121] As the insulators 320, 322, 324, and 326, for example, silicon oxide, silicon oxynitride, silicon nitride oxide, silicon nitride, aluminum oxide, aluminum oxynitride, aluminum nitride oxide, aluminum nitride, or the like can be used.

[0122] The insulator 322 may function as a planarizing film that planarizes steps caused by the transistor 300 provided thereunder. For example, the top surface of the insulator 322 may be planarized by a planarization process using a chemical mechanical polishing (CMP) method or the like to improve the planarity.

[0123] The insulator 324 is preferably a film having a barrier property that prevents hydrogen or impurities from diffusing from the substrate 311 or the transistor 300 to a region where the transistor 500 is provided.

[0124] As an example of a film having a barrier property against hydrogen, for example, silicon nitride formed by a CVD method can be used. Here, when hydrogen diffuses into a semiconductor element having an oxide semiconductor such as the transistor 500, the characteristics of the semiconductor element may deteriorate. Therefore, it is preferable to use a film that suppresses the diffusion of hydrogen between the transistor 500 and the transistor 300. Specifically, the film that suppresses the diffusion of hydrogen is a film that releases a small amount of hydrogen.

[0125] The amount of desorption of hydrogen can be analyzed, for example, by using a temperature programmed desorption spectrometry (TDS) method. For example, the amount of desorption of hydrogen from the insulator 324 is calculated as 10×10 per area of ​​the insulator 324 when the surface temperature of the film is in the range of 50° C. to 500° C. in the TDS analysis. 15 atoms / cm 2 Less than or equal to 5×10 15 atoms / cm2 The following is acceptable.

[0126] The insulator 326 preferably has a lower dielectric constant than the insulator 324. For example, the relative dielectric constant of the insulator 326 is preferably less than 4, and more preferably less than 3. For example, the relative dielectric constant of the insulator 326 is preferably 0.7 times or less, and more preferably 0.6 times or less, the relative dielectric constant of the insulator 324. By using a material with a low dielectric constant as the interlayer film, the parasitic capacitance generated between wirings can be reduced.

[0127] Conductors 328 and 330, which connect to the capacitor 600 or the transistor 500, are embedded in the insulators 320, 322, 324, and 326. The conductors 328 and 330 function as plugs or wiring. A plurality of conductors that function as plugs or wiring may be collectively given the same reference numeral. In this specification and the like, the wiring and the plug connected to the wiring may be integral. That is, a part of the conductor may function as the wiring, and a part of the conductor may function as the plug.

[0128] As the material for each plug and wiring (conductor 328, conductor 330, etc.), a conductive material such as a metal material, an alloy material, a metal nitride material, or a metal oxide material can be used in a single layer or a laminated layer. It is preferable to use a high melting point material such as tungsten or molybdenum that has both heat resistance and conductivity, and it is preferable to use tungsten. Alternatively, it is preferable to form it from a low resistance conductive material such as aluminum or copper. By using a low resistance conductive material, it is possible to reduce the wiring resistance.

[0129] A wiring layer may be provided over the insulator 326 and the conductor 330. For example, in FIG. 5, an insulator 350, an insulator 352, and an insulator 354 are stacked in this order. A conductor 356 is formed in the insulator 350, the insulator 352, and the insulator 354. The conductor 356 functions as a plug or wiring connected to the transistor 300. Note that the conductor 356 can be provided using a material similar to that of the conductor 328 and the conductor 330.

[0130] Note that, for example, the insulator 350 is preferably an insulator having a barrier property against hydrogen, similar to the insulator 324. The conductor 356 preferably includes a conductor having a barrier property against hydrogen. In particular, a conductor having a barrier property against hydrogen is formed in an opening of the insulator 350 having a barrier property against hydrogen. With this structure, the transistor 300 and the transistor 500 can be separated by a barrier layer, and diffusion of hydrogen from the transistor 300 to the transistor 500 can be suppressed.

[0131] Note that, for example, tantalum nitride or the like may be used as the conductor having a barrier property against hydrogen. By stacking tantalum nitride and tungsten having high conductivity, it is possible to suppress diffusion of hydrogen from the transistor 300 while maintaining the conductivity of the wiring. In this case, a structure in which the tantalum nitride layer having a barrier property against hydrogen is in contact with the insulator 350 having a barrier property against hydrogen is preferable.

[0132] A wiring layer may be provided on the insulator 354 and the conductor 356. For example, in FIG. 5, an insulator 360, an insulator 362, and an insulator 364 are stacked in this order. A conductor 366 is formed in the insulator 360, the insulator 362, and the insulator 364. The conductor 366 functions as a plug or a wiring. The conductor 366 can be provided using a material similar to that of the conductor 328 and the conductor 330.

[0133] Note that, for example, the insulator 360 is preferably an insulator having a barrier property against hydrogen, similar to the insulator 324. The conductor 366 preferably includes a conductor having a barrier property against hydrogen. In particular, a conductor having a barrier property against hydrogen is formed in an opening of the insulator 360 having a barrier property against hydrogen. With this structure, the transistor 300 and the transistor 500 can be separated by a barrier layer, and diffusion of hydrogen from the transistor 300 to the transistor 500 can be suppressed.

[0134] A wiring layer may be provided over the insulator 364 and the conductor 366. For example, in FIG. 5, an insulator 370, an insulator 372, and an insulator 374 are stacked in this order. A conductor 376 is formed in the insulator 370, the insulator 372, and the insulator 374. The conductor 376 functions as a plug or a wiring. The conductor 376 can be provided using a material similar to that of the conductor 328 and the conductor 330.

[0135] Note that, for example, the insulator 370 is preferably an insulator having a barrier property against hydrogen, similar to the insulator 324. The conductor 376 preferably includes a conductor having a barrier property against hydrogen. In particular, a conductor having a barrier property against hydrogen is formed in an opening of the insulator 370 having a barrier property against hydrogen. With this structure, the transistor 300 and the transistor 500 can be separated by a barrier layer, and diffusion of hydrogen from the transistor 300 to the transistor 500 can be suppressed.

[0136] A wiring layer may be provided over the insulator 374 and the conductor 376. For example, in FIG. 5, an insulator 380, an insulator 382, ​​and an insulator 384 are stacked in this order. A conductor 386 is formed in the insulator 380, the insulator 382, ​​and the insulator 384. The conductor 386 functions as a plug or a wiring. The conductor 386 can be provided using a material similar to that of the conductor 328 and the conductor 330.

[0137] Note that, for example, the insulator 380 is preferably an insulator having a barrier property against hydrogen, similar to the insulator 324. The conductor 386 preferably includes a conductor having a barrier property against hydrogen. In particular, a conductor having a barrier property against hydrogen is formed in an opening of the insulator 380 having a barrier property against hydrogen. With this structure, the transistor 300 and the transistor 500 can be separated by a barrier layer, and diffusion of hydrogen from the transistor 300 to the transistor 500 can be suppressed.

[0138] In the above, a wiring layer including the conductor 356, a wiring layer including the conductor 366, a wiring layer including the conductor 376, and a wiring layer including the conductor 386 have been described, but the semiconductor device of this embodiment is not limited to this. There may be three or fewer wiring layers similar to the wiring layer including the conductor 356, or there may be five or more wiring layers similar to the wiring layer including the conductor 356.

[0139] An insulator 510, an insulator 512, an insulator 514, and an insulator 516 are stacked in this order on the insulator 384. Any of the insulator 510, the insulator 512, the insulator 514, and the insulator 516 is preferably made of a substance that has a barrier property against oxygen or hydrogen.

[0140] For example, the insulator 510 and the insulator 514 are preferably formed using a film having a barrier property that prevents hydrogen or impurities from diffusing from the substrate 311 or a region where the transistor 300 is provided to a region where the transistor 500 is provided. Therefore, a material similar to that of the insulator 324 can be used.

[0141] As an example of a film having a barrier property against hydrogen, silicon nitride formed by a CVD method can be used. Here, when hydrogen diffuses into a semiconductor element having an oxide semiconductor such as the transistor 500, the characteristics of the semiconductor element may deteriorate. Therefore, it is preferable to use a film that suppresses the diffusion of hydrogen between the transistor 500 and the transistor 300. Specifically, the film that suppresses the diffusion of hydrogen is a film that releases a small amount of hydrogen.

[0142] As a film having a barrier property against hydrogen, for example, the insulator 510 and the insulator 514 are preferably made of a metal oxide such as aluminum oxide, hafnium oxide, or tantalum oxide.

[0143] In particular, aluminum oxide has a high blocking effect of preventing the film from permeating both oxygen and impurities such as hydrogen and moisture, which are factors that cause fluctuations in the electrical characteristics of a transistor. Therefore, aluminum oxide can prevent impurities such as hydrogen and moisture from entering the transistor 500 during and after the transistor manufacturing process. In addition, aluminum oxide can suppress the release of oxygen from the oxide that constitutes the transistor 500. Therefore, aluminum oxide is suitable for use as a protective film for the transistor 500.

[0144] For example, the insulator 512 and the insulator 516 can be formed using a material similar to that of the insulator 320. By using a material with a relatively low dielectric constant as an interlayer film, parasitic capacitance between wirings can be reduced. For example, the insulator 512 and the insulator 516 can be formed using a silicon oxide film, a silicon oxynitride film, or the like.

[0145] A conductor 518 and the like are embedded in the insulator 510, the insulator 512, the insulator 514, and the insulator 516. The conductor 518 functions as a plug or a wiring connected to the capacitor 600 or the transistor 300. The conductor 518 can be formed using a material similar to that of the conductor 328 and the conductor 330.

[0146] In particular, the insulator 510 and the conductor 518 in the region in contact with the insulator 514 are preferably conductors having barrier properties against oxygen, hydrogen, and water. With this structure, the transistor 300 and the transistor 500 can be separated by a layer having barrier properties against oxygen, hydrogen, and water, and diffusion of hydrogen from the transistor 300 to the transistor 500 can be suppressed.

[0147] Above the insulator 516 is a transistor 500 .

[0148] As shown in FIGS. 6A and 6B, the transistor 500 includes an insulator 520 disposed on an insulator 516, an insulator 522 disposed on the insulator 520, an insulator 524 disposed on the insulator 522, an oxide 530a disposed on the insulator 524, an oxide 530b disposed on the oxide 530a, a conductor 542a and a conductor 542b disposed apart from each other on the oxide 530b, and a conductor 542a and a conductor 542b disposed on the oxide 530b. The semiconductor device further includes an insulator 580 disposed on conductor 542b and having an opening formed thereon overlapping conductor 542a and conductor 542b, a conductor 560 disposed in the opening, an insulator 550 disposed among oxide 530b, conductor 542a, conductor 542b, and insulator 580, and conductor 560, and an oxide 530c disposed among oxide 530b, conductor 542a, conductor 542b, and insulator 580, and insulator 550.

[0149] 6(A) and (B), it is preferable that an insulator 544 be disposed between the oxide 530a, the oxide 530b, the conductor 542a, and the conductor 542b and the insulator 580. It is preferable that the conductor 560 has a conductor 560a provided inside the insulator 550 and a conductor 560b provided inside the conductor 560a, as shown in FIGS. 6(A) and (B). It is preferable that an insulator 574 be disposed over the insulator 580, the conductor 560, and the insulator 550, as shown in FIGS. 6(A) and (B).

[0150] In the following, the oxide 530a, the oxide 530b, and the oxide 530c may be collectively referred to as the oxide 530. In addition, the conductor 542a and the conductor 542b may be collectively referred to as the conductor 542.

[0151] In the transistor 500, a three-layer structure of the oxide 530a, the oxide 530b, and the oxide 530c is shown in the region where the channel is formed and in the vicinity thereof, but the present invention is not limited thereto. For example, a single layer of the oxide 530b, a two-layer structure of the oxide 530b and the oxide 530a, a two-layer structure of the oxide 530b and the oxide 530c, or a stacked structure of four or more layers may be provided. In the transistor 500, the conductor 560 is shown as having a two-layer stacked structure, but the present invention is not limited thereto. For example, the conductor 560 may have a single-layer structure or a stacked structure of three or more layers. The transistor 500 shown in FIG. 5 and FIG. 6(A)(B) is an example, and the present invention is not limited thereto, and an appropriate transistor may be used depending on the circuit configuration and the driving method.

[0152] Here, the conductor 560 functions as a gate electrode of the transistor, and the conductors 542a and 542b function as a source electrode and a drain electrode, respectively. As described above, the conductor 560 is formed so as to be embedded in the opening of the insulator 580 and in the region sandwiched between the conductors 542a and 542b. The conductors 560, 542a, and 542b are arranged in a self-aligned manner with respect to the opening of the insulator 580. That is, in the transistor 500, the gate electrode can be arranged in a self-aligned manner between the source electrode and the drain electrode. Therefore, the conductor 560 can be formed without providing a margin for alignment, so that the area occupied by the transistor 500 can be reduced. This allows the semiconductor device to be miniaturized and highly integrated.

[0153] Furthermore, since the conductor 560 is formed in a self-aligned manner in the region between the conductor 542a and the conductor 542b, the conductor 560 does not have a region that overlaps with the conductor 542a or the conductor 542b. This makes it possible to reduce the parasitic capacitance formed between the conductor 560 and the conductor 542a and between the conductor 560 and the conductor 542b. This makes it possible to improve the switching speed of the transistor 500 and provide high frequency characteristics.

[0154] The insulator 550 functions as a gate insulating film.

[0155] Here, the insulator 524 in contact with the oxide 530 preferably contains more oxygen than the oxygen required for the stoichiometric composition. That is, an excess oxygen region is preferably formed in the insulator 524. By providing such an insulator containing excess oxygen in contact with the oxide 530, oxygen vacancies in the oxide 530 can be reduced and the reliability of the transistor 500 can be improved.

[0156] Specifically, it is preferable to use an oxide material from which some oxygen is released by heating as an insulator having an excess oxygen region. An oxide material from which oxygen is released by heating is an oxide material from which the amount of released oxygen converted into oxygen atoms is 1.0×10 18 atoms / cm 3 More than 1.0×10 19 atoms / cm 3 More preferably, 2.0×10 19 atoms / cm 3 or more, or 3.0×10 20 atoms / cm 3 The oxide film is one having the above-mentioned properties. The surface temperature of the film during the TDS analysis is preferably in the range of 100° C. or more and 700° C. or less, or 100° C. or more and 400° C. or less.

[0157] When the insulator 524 has an excess oxygen region, it is preferable that the insulator 522 has a function of suppressing the diffusion of oxygen (eg, oxygen atoms, oxygen molecules, etc.) (the oxygen is less likely to permeate).

[0158] Since the insulator 522 has a function of suppressing diffusion of oxygen and impurities, oxygen in the oxide 530 does not diffuse toward the insulator 520, which is preferable.

[0159] The insulator 522 is preferably a single layer or a multilayer insulator containing a so-called high-k material, such as aluminum oxide, hafnium oxide, tantalum oxide, zirconium oxide, lead zirconate titanate (PZT), strontium titanate (SrTiO3), or (Ba,Sr)TiO3 (BST). As transistors become smaller and more highly integrated, problems such as leakage current may occur due to the thinning of the gate insulating film. By using a high-k material for the insulator that functions as the gate insulating film, it is possible to reduce the gate potential during transistor operation while maintaining the physical film thickness.

[0160] In particular, it is preferable to use an insulator containing an oxide of one or both of aluminum and hafnium, which are insulating materials having a function of suppressing the diffusion of impurities and oxygen (the oxygen is unlikely to permeate through them). As an insulator containing an oxide of one or both of aluminum and hafnium, it is preferable to use aluminum oxide, hafnium oxide, an oxide containing aluminum and hafnium (hafnium aluminate), or the like. When the insulator 522 is formed using such a material, the insulator 522 functions as a layer that suppresses the release of oxygen from the oxide 530 and the intrusion of impurities such as hydrogen into the oxide 530 from the periphery of the transistor 500.

[0161] Alternatively, for example, aluminum oxide, bismuth oxide, germanium oxide, niobium oxide, silicon oxide, titanium oxide, tungsten oxide, yttrium oxide, or zirconium oxide may be added to these insulators. Alternatively, these insulators may be nitrided. Silicon oxide, silicon oxynitride, or silicon nitride may be stacked on the above insulators.

[0162] In addition, the insulator 520 is preferably thermally stable. For example, silicon oxide and silicon oxynitride are preferable because they are thermally stable. In addition, by combining a high-k material insulator with silicon oxide or silicon oxynitride, it is possible to obtain the insulator 520 having a thermally stable laminated structure with a high dielectric constant.

[0163] The insulator 520, the insulator 522, and the insulator 524 may have a layered structure of two or more layers. In that case, the layers are not limited to being made of the same material, and may be made of different materials.

[0164] In the transistor 500, it is preferable to use a metal oxide that functions as an oxide semiconductor for the oxide 530 including the channel formation region. For example, a metal oxide such as In-M-Zn oxide (wherein the element M is one or more elements selected from aluminum, gallium, yttrium, copper, vanadium, beryllium, boron, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, magnesium, etc.) may be used for the oxide 530. Alternatively, In-Ga oxide or In-Zn oxide may be used for the oxide 530.

[0165] The metal oxide that functions as a channel formation region in the oxide 530 preferably has a band gap of 2 eV or more, preferably 2.5 eV or more. In this manner, by using a metal oxide with a wide band gap, the off-state current of the transistor can be reduced.

[0166] The oxide 530 has the oxide 530a below the oxide 530b, so that the diffusion of impurities from structures formed below the oxide 530a to the oxide 530b can be suppressed. Also, the oxide 530 has the oxide 530c on the oxide 530b, so that the diffusion of impurities from structures formed above the oxide 530c to the oxide 530b can be suppressed.

[0167] The oxide 530 preferably has a laminated structure of oxides having different atomic ratios of metal atoms. Specifically, in the metal oxide used for the oxide 530a, the atomic ratio of element M among the constituent elements is preferably larger than the atomic ratio of element M among the constituent elements in the metal oxide used for the oxide 530b. In addition, in the metal oxide used for the oxide 530a, the atomic ratio of element M to In is preferably larger than the atomic ratio of element M to In in the metal oxide used for the oxide 530b. In addition, in the metal oxide used for the oxide 530b, the atomic ratio of In to element M is preferably larger than the atomic ratio of In to element M in the metal oxide used for the oxide 530a. In addition, the oxide 530c can use a metal oxide that can be used for the oxide 530a or the oxide 530b.

[0168] In addition, the energy of the conduction band minimum of the oxide 530a and the oxide 530c is preferably higher than that of the oxide 530b, or in other words, the electron affinity of the oxide 530a and the oxide 530c is preferably smaller than that of the oxide 530b.

[0169] Here, the energy level of the conduction band minimum changes gradually at the junction of the oxide 530a, the oxide 530b, and the oxide 530c. In other words, it can be said that the energy level of the conduction band minimum at the junction of the oxide 530a, the oxide 530b, and the oxide 530c changes continuously or is a continuous junction. To achieve this, it is preferable to reduce the defect level density of the mixed layer formed at the interface between the oxide 530a and the oxide 530b and the interface between the oxide 530b and the oxide 530c.

[0170] Specifically, the oxides 530a and 530b, and the oxides 530b and 530c have a common element other than oxygen (as a main component), so that a mixed layer with a low density of defect states can be formed. For example, when the oxide 530b is an In-Ga-Zn oxide, the oxides 530a and 530c may be made of an In-Ga-Zn oxide, a Ga-Zn oxide, or a gallium oxide.

[0171] At this time, the main carrier path is the oxide 530b. By configuring the oxide 530a and the oxide 530c as described above, the defect state density at the interface between the oxide 530a and the oxide 530b and at the interface between the oxide 530b and the oxide 530c can be reduced. Therefore, the effect of interface scattering on carrier conduction is reduced, and the transistor 500 can obtain a high on-current.

[0172] Conductors 542 (conductors 542a and 542b) functioning as a source electrode and a drain electrode are provided on the oxide 530b. As the conductor 542, it is preferable to use a metal element selected from aluminum, chromium, copper, silver, gold, platinum, tantalum, nickel, titanium, molybdenum, tungsten, hafnium, vanadium, niobium, manganese, magnesium, zirconium, beryllium, indium, ruthenium, iridium, strontium, and lanthanum, an alloy containing the above-mentioned metal elements as a component, or an alloy combining the above-mentioned metal elements. For example, it is preferable to use tantalum nitride, titanium nitride, tungsten, 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. In addition, tantalum nitride, titanium nitride, nitrides containing titanium and aluminum, nitrides containing tantalum and aluminum, ruthenium oxide, ruthenium nitride, oxides containing strontium and ruthenium, and oxides containing lanthanum and nickel are preferred because they are conductive materials that are difficult to oxidize or materials that maintain their conductivity even when they absorb oxygen.

[0173] 6A, a region 543 (regions 543a and 543b) may be formed as a low-resistance region at the interface between the oxide 530 and the conductor 542 and in its vicinity. In this case, the region 543a functions as one of the source region and the drain region, and the region 543b functions as the other of the source region and the drain region. A channel formation region is formed in a region sandwiched between the regions 543a and 543b.

[0174] By providing the conductor 542 so as to be in contact with the oxide 530, the oxygen concentration in the region 543 may be reduced. Also, a metal compound layer containing a metal contained in the conductor 542 and a component of the oxide 530 may be formed in the region 543. In such a case, the carrier density in the region 543 increases, and the region 543 becomes a low-resistance region.

[0175] The insulator 544 is provided to cover the conductor 542 and suppresses oxidation of the conductor 542. In this case, the insulator 544 may be provided to cover the side surface of the oxide 530 and to be in contact with the insulator 524.

[0176] The insulator 544 can be a metal oxide containing one or more elements selected from hafnium, aluminum, gallium, yttrium, zirconium, tungsten, titanium, tantalum, nickel, germanium, magnesium, and the like.

[0177] In particular, it is preferable to use, as the insulator 544, an insulator containing an oxide of either or both of aluminum and hafnium, such as aluminum oxide, hafnium oxide, or an oxide containing aluminum and hafnium (hafnium aluminate). In particular, hafnium aluminate has higher heat resistance than a hafnium oxide film. Therefore, it is preferable because it is less likely to crystallize in a heat treatment in a later process. Note that, if the conductor 542 is a material having oxidation resistance or the conductivity does not decrease significantly even when oxygen is absorbed, the insulator 544 is not an essential component. It may be designed appropriately depending on the desired transistor characteristics.

[0178] The insulator 550 functions as a gate insulating film. The insulator 550 is preferably disposed in contact with the inside (top and side surfaces) of the oxide 530c. The insulator 550 is preferably formed using an insulator that releases oxygen when heated. For example, in a TDS analysis, the amount of released oxygen converted into oxygen atoms is 1.0×10 18 atoms / cm 3 More than 1.0×10 19 atoms / cm 3 More preferably, 2.0×10 19 atoms / cm 3 or more, or 3.0×10 20 atoms / cm 3 The oxide film is as described above. The surface temperature of the film during the TDS analysis is preferably in the range of 100° C. or more and 700° C. or less.

[0179] Specifically, silicon oxide having excess oxygen, 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, and silicon oxide having vacancies can be used. In particular, silicon oxide and silicon oxynitride are preferable because they are stable against heat.

[0180] By providing an insulator that releases oxygen when heated as the insulator 550 in contact with the top surface of the oxide 530c, oxygen can be effectively supplied from the insulator 550 to the channel formation region of the oxide 530b through the oxide 530c. Similarly to the insulator 524, the concentration of impurities such as water or hydrogen in the insulator 550 is preferably reduced. The thickness of the insulator 550 is preferably 1 nm or more and 20 nm or less.

[0181] Furthermore, in order to efficiently supply excess oxygen contained in the insulator 550 to the oxide 530, a metal oxide may be provided between the insulator 550 and the conductor 560. The metal oxide preferably suppresses oxygen diffusion from the insulator 550 to the conductor 560. By providing a metal oxide that suppresses oxygen diffusion, the diffusion of excess oxygen from the insulator 550 to the conductor 560 is suppressed. That is, a decrease in the amount of excess oxygen supplied to the oxide 530 can be suppressed. Furthermore, oxidation of the conductor 560 due to the excess oxygen can be suppressed. As the metal oxide, a material that can be used for the insulator 544 may be used.

[0182] The conductor 560 functioning as a gate electrode is shown as having a two-layer structure in FIGS. 6A and 6B, but may have a single-layer structure or a stacked structure of three or more layers.

[0183] Conductor 560a is preferably made of a conductive material having a function of suppressing the diffusion of impurities such as hydrogen atoms, hydrogen molecules, water molecules, nitrogen atoms, nitrogen molecules, nitrogen oxide molecules (N2O, NO, NO2, etc.), and copper atoms. Alternatively, conductive material having a function of suppressing the diffusion of oxygen (for example, at least one of oxygen atoms, oxygen molecules, etc.) is preferably used. Conductor 560a has a function of suppressing the diffusion of oxygen, so that it is possible to suppress the oxidation of conductor 560b due to oxygen contained in insulator 550, which leads to a decrease in conductivity. As a conductive material having a function of suppressing the diffusion of oxygen, for example, tantalum, tantalum nitride, ruthenium, or ruthenium oxide is preferably used.

[0184] The conductor 560b is preferably made of a conductive material containing tungsten, copper, or aluminum as a main component. The conductor 560b also functions as wiring, so it is preferable to use a conductor with high conductivity. For example, a conductive material containing tungsten, copper, or aluminum as a main component can be used. The conductor 560b may have a layered structure, for example, a layered structure of titanium, titanium nitride, and the above conductive material.

[0185] The insulator 580 is provided on the conductor 542 via the insulator 544. The insulator 580 preferably has an excess oxygen region. For example, the insulator 580 preferably has silicon oxide, silicon oxynitride, silicon nitride oxide, silicon nitride, silicon oxide to which fluorine has been added, silicon oxide to which carbon has been added, silicon oxide to which carbon and nitrogen have been added, silicon oxide having voids, or resin. In particular, silicon oxide and silicon oxynitride are preferable because they are thermally stable. In particular, silicon oxide and silicon oxide having voids are preferable because an excess oxygen region can be easily formed in a later step.

[0186] By providing the insulator 580, which releases oxygen when heated, in contact with the oxide 530c, oxygen in the insulator 580 can be efficiently supplied to the oxide 530 through the oxide 530c. Note that the concentration of impurities such as water or hydrogen in the insulator 580 is preferably reduced.

[0187] The opening of insulator 580 is formed to overlap the region between conductor 542a and conductor 542b, so that conductor 560 is formed so as to be embedded in the opening of insulator 580 and the region sandwiched between conductor 542a and conductor 542b.

[0188] In miniaturizing a semiconductor device, it is necessary to shorten the gate length, but it is also necessary to prevent the conductivity of the conductor 560 from decreasing. If the film thickness of the conductor 560 is increased for that purpose, the conductor 560 may have a shape with a high aspect ratio. In this embodiment, the conductor 560 is provided so as to be embedded in the opening of the insulator 580, so that even if the conductor 560 has a shape with a high aspect ratio, the conductor 560 can be formed without collapsing during the process.

[0189] The insulator 574 is preferably provided in contact with the top surface of the insulator 580, the top surface of the conductor 560, and the top surface of the insulator 550. By forming the insulator 574 by a sputtering method, excess oxygen regions can be provided in the insulator 550 and the insulator 580. This allows oxygen to be supplied from the excess oxygen regions into the oxide 530.

[0190] For example, the insulator 574 can be a metal oxide containing one or more elements selected from hafnium, aluminum, gallium, yttrium, zirconium, tungsten, titanium, tantalum, nickel, germanium, magnesium, and the like.

[0191] In particular, aluminum oxide has high barrier properties and can suppress the diffusion of hydrogen and nitrogen even in a thin film with a thickness of 0.5 nm to 3.0 nm. Therefore, aluminum oxide formed by sputtering can function as a barrier film against impurities such as hydrogen as well as an oxygen source.

[0192] An insulator 581 functioning as an interlayer film is preferably provided over the insulator 574. Like the insulator 524, the insulator 581 preferably has a reduced concentration of impurities such as water or hydrogen.

[0193] Conductor 540a and conductor 540b are arranged in openings formed in insulator 581, insulator 574, insulator 580, and insulator 544. Conductor 540a and conductor 540b are provided facing each other with conductor 560 interposed therebetween. Conductor 540a and conductor 540b have the same configuration as conductor 546 and conductor 548, which will be described later.

[0194] An insulator 582 is provided over the insulator 581. The insulator 582 is preferably made of a substance that has a barrier property against oxygen and hydrogen. Therefore, the insulator 582 can be made of a material similar to that of the insulator 514. For example, the insulator 582 is preferably made of a metal oxide such as aluminum oxide, hafnium oxide, or tantalum oxide.

[0195] In particular, aluminum oxide has a high blocking effect of preventing the film from permeating both oxygen and impurities such as hydrogen and moisture, which are factors that cause fluctuations in the electrical characteristics of a transistor. Therefore, aluminum oxide can prevent impurities such as hydrogen and moisture from entering the transistor 500 during and after the transistor manufacturing process. In addition, aluminum oxide can suppress the release of oxygen from the oxide that constitutes the transistor 500. Therefore, aluminum oxide is suitable for use as a protective film for the transistor 500.

[0196] An insulator 586 is provided over the insulator 582. The insulator 586 can be formed using a material similar to that of the insulator 320. By using a material with a relatively low dielectric constant as an interlayer film, parasitic capacitance between wirings can be reduced. For example, a silicon oxide film, a silicon oxynitride film, or the like can be used as the insulator 586.

[0197] In addition, conductors 546, 548, etc. are embedded in insulators 520, 522, 524, 544, 580, 574, 581, 582, and 586.

[0198] The conductor 546 and the conductor 548 function as a plug or a wiring connected to the capacitor 600, the transistor 500, or the transistor 300. The conductor 546 and the conductor 548 can be formed using a material similar to that of the conductor 328 and the conductor 330.

[0199] Next, a capacitor 600 is provided above the transistor 500. The capacitor 600 includes a conductor 610, a conductor 620, and an insulator 630.

[0200] A conductor 612 may be provided over the conductor 546 and the conductor 548. The conductor 612 functions as a plug or a wiring connected to the transistor 500. The conductor 610 functions as an electrode of the capacitor 600. Note that the conductor 612 and the conductor 610 can be formed at the same time.

[0201] A metal film containing an element selected from molybdenum, titanium, tantalum, tungsten, aluminum, copper, chromium, neodymium, and scandium, or a metal nitride film containing the above-mentioned element (tantalum nitride film, titanium nitride film, molybdenum nitride film, tungsten nitride film), etc. can be used for the conductor 612 and the conductor 610. Alternatively, a conductive material such as indium tin oxide, indium oxide containing tungsten oxide, indium zinc oxide containing tungsten oxide, indium oxide containing titanium oxide, indium tin oxide containing titanium oxide, indium zinc oxide, or indium tin oxide with added silicon oxide can also be used.

[0202] 5, the conductor 612 and the conductor 610 are shown to have a single-layer structure, but are not limited to this structure and may have a laminated structure of two or more layers. For example, a conductor having a barrier property and a conductor having high adhesion to the conductor having high conductivity may be formed between a conductor having a barrier property and a conductor having high conductivity.

[0203] The conductor 620 is provided so as to overlap with the conductor 610 with the insulator 630 interposed therebetween. Note that the conductor 620 can be made of a conductive material such as a metal material, an alloy material, or a metal oxide material. It is preferable to use a high melting point material such as tungsten or molybdenum that has both heat resistance and conductivity, and it is particularly preferable to use tungsten. When the conductor 620 is formed simultaneously with other structures such as a conductor, a low resistance metal material such as Cu (copper) or Al (aluminum) may be used.

[0204] An insulator 650 is provided over the conductor 620 and the insulator 630. The insulator 650 can be provided using a material similar to that of the insulator 320. The insulator 650 may also function as a planarizing film that covers the uneven shape underneath.

[0205] By using this structure, in a semiconductor device including a transistor having an oxide semiconductor, a change in electrical characteristics can be suppressed and reliability can be improved. Alternatively, a transistor having an oxide semiconductor and having a large on-state current can be provided. Alternatively, a transistor having an oxide semiconductor and having a small off-state current can be provided. Alternatively, a transistor having an oxide semiconductor and having a high withstand voltage between the source and drain can be provided.

[0206] <Example of transistor structure> Note that the transistor 500 of the semiconductor device described in this embodiment is not limited to the above structure. Hereinafter, examples of a structure that can be used for the transistor 500 will be described.

[0207] <Transistor structure example 1> An example of the structure of a transistor 510A will be described with reference to Figures 7(A), (B), and (C). Figure 7(A) is a top view of the transistor 510A. Figure 7(B) is a cross-sectional view of a portion indicated by dashed line L1-L2 in Figure 7(A). Figure 7(C) is a cross-sectional view of a portion indicated by dashed line W1-W2 in Figure 7(A). Note that in the top view of Figure 7(A), some elements are omitted for clarity.

[0208] 7A, 7B, and 7C show a transistor 510A, and insulators 511, 512, 514, 516, 580, 582, and 584 which function as interlayer films. Also shown is a conductor 546 (conductor 546a and conductor 546b) which is electrically connected to the transistor 510A and functions as a contact plug.

[0209] Transistor 510A has a conductor 560 (conductor 560a and conductor 560b) that functions as a gate electrode, an insulator 550 that functions as a gate insulating film, an oxide 530 (oxide 530a, oxide 530b, and oxide 530c) having a region where a channel is formed, a conductor 542a that functions as one of a source or a drain, a conductor 542b that functions as the other of the source or a drain, and an insulator 574.

[0210] 7, the oxide 530c, the insulator 550, and the conductor 560 are disposed in an opening in the insulator 580 with the insulator 574 interposed therebetween. The oxide 530c, the insulator 550, and the conductor 560 are disposed between the conductor 542a and the conductor 542b.

[0211] The insulators 511 and 512 function as interlayer films.

[0212] As the interlayer film, a single layer or a laminated layer of an insulator such as silicon oxide, silicon oxynitride, silicon nitride oxide, aluminum oxide, hafnium oxide, tantalum oxide, zirconium oxide, lead zirconate titanate (PZT), strontium titanate (SrTiO3), or (Ba,Sr)TiO3 (BST) can be used. Alternatively, for example, aluminum oxide, bismuth oxide, germanium oxide, niobium oxide, silicon oxide, titanium oxide, tungsten oxide, yttrium oxide, or zirconium oxide may be added to these insulators. Alternatively, these insulators may be nitrided. Silicon oxide, silicon oxynitride, or silicon nitride may be laminated on the above insulators.

[0213] For example, the insulator 511 preferably functions as a barrier film that suppresses impurities such as water or hydrogen from entering the transistor 510A from the substrate side. Therefore, the insulator 511 is preferably made of an insulating material that has a function of suppressing the diffusion of impurities such as hydrogen atoms, hydrogen molecules, water molecules, and copper atoms (through which the above impurities are unlikely to permeate). Alternatively, it is preferable to use an insulating material that has a function of suppressing the diffusion of oxygen (for example, at least one of oxygen atoms, oxygen molecules, etc.) (through which the above oxygen is unlikely to permeate). For example, aluminum oxide or silicon nitride may be used as the insulator 511. With this configuration, it is possible to suppress the diffusion of impurities such as hydrogen and water from the substrate side to the transistor 510A side through the insulator 511.

[0214] For example, the insulator 512 preferably has a lower dielectric constant than the insulator 511. By using a material with a low dielectric constant as an interlayer film, parasitic capacitance generated between wirings can be reduced.

[0215] In transistor 510A, conductor 560 may function as a gate electrode.

[0216] The insulator 514 and the insulator 516 function as an interlayer film, similar to the insulator 511 or the insulator 512. For example, the insulator 514 preferably functions as a barrier film that suppresses impurities such as water or hydrogen from entering the transistor 510A from the substrate side. With this structure, impurities such as hydrogen and water can be suppressed from diffusing from the substrate side to the transistor 510A side through the insulator 514. For example, the insulator 516 preferably has a lower dielectric constant than the insulator 514. By using a material with a low dielectric constant as an interlayer film, parasitic capacitance generated between wirings can be reduced.

[0217] The insulator 522 preferably has a barrier property. When the insulator 522 has a barrier property, it functions as a layer that prevents impurities such as hydrogen from entering the transistor 510A from the periphery of the transistor 510A.

[0218] The insulator 522 is preferably a single layer or a multilayer insulator containing a so-called high-k material, such as aluminum oxide, hafnium oxide, oxide containing aluminum and hafnium (hafnium aluminate), tantalum oxide, zirconium oxide, lead zirconate titanate (PZT), strontium titanate (SrTiO3), or (Ba,Sr)TiO3 (BST). As transistors become smaller and more highly integrated, problems such as leakage current may occur due to the thinning of the gate insulating film. By using a high-k material for the insulator that functions as the gate insulating film, it is possible to reduce the gate potential during transistor operation while maintaining the physical film thickness.

[0219] For example, the insulator 522 is preferably thermally stable. For example, silicon oxide and silicon oxynitride are preferable because they are thermally stable. In addition, by combining a high-k material insulator with silicon oxide or silicon oxynitride, a thermally stable laminated insulator 522 with a high dielectric constant can be obtained.

[0220] The oxide 530 having a region functioning as a channel formation region includes an oxide 530a, an oxide 530b on the oxide 530a, and an oxide 530c on the oxide 530b. By providing the oxide 530a under the oxide 530b, it is possible to suppress the diffusion of impurities from a structure formed below the oxide 530a to the oxide 530b. By providing the oxide 530c on the oxide 530b, it is possible to suppress the diffusion of impurities from a structure formed above the oxide 530c to the oxide 530b. An oxide semiconductor, which is one of the above-mentioned metal oxides, can be used as the oxide 530.

[0221] Note that the oxide 530c is preferably provided in an opening in the insulator 580 via the insulator 574. When the insulator 574 has a barrier property, diffusion of impurities from the insulator 580 to the oxide 530 can be suppressed.

[0222] One of the conductor 542a and the conductor 542b functions as a source electrode and the other functions as a drain electrode.

[0223] The conductor 542a and the conductor 542b can be made of a metal such as aluminum, titanium, chromium, nickel, copper, yttrium, zirconium, molybdenum, silver, tantalum, or tungsten, or an alloy containing these as a main component. In particular, a metal nitride film such as tantalum nitride is preferable because it has a barrier property against hydrogen or oxygen and has high oxidation resistance.

[0224] Although a single-layer structure is shown in FIG. 7, a laminated structure of two or more layers may be used. For example, a tantalum nitride film and a tungsten film may be laminated. A titanium film and an aluminum film may be laminated. A two-layer structure in which an aluminum film is laminated on a tungsten film, a two-layer structure in which a copper film is laminated on a copper-magnesium-aluminum alloy film, a two-layer structure in which a copper film is laminated on a titanium film, or a two-layer structure in which a copper film is laminated on a tungsten film may be used.

[0225] In addition, there are three-layer structures in which a titanium film or titanium nitride film is laminated with an aluminum film or copper film on the titanium film or titanium nitride film, and a titanium film or titanium nitride film is further formed thereon, and a three-layer structure in which a molybdenum film or molybdenum nitride film is laminated with an aluminum film or copper film on the molybdenum film or molybdenum nitride film, and a molybdenum film or molybdenum nitride film is further formed thereon, etc. Note that a transparent conductive material containing indium oxide, tin oxide, or zinc oxide may also be used.

[0226] A barrier layer may be provided over the conductor 542. The barrier layer is preferably formed using a substance having a barrier property against oxygen or hydrogen. With this structure, oxidation of the conductor 542 can be suppressed when the insulator 574 is formed.

[0227] For example, a metal oxide can be used for the barrier layer. In particular, it is preferable to use an insulating film having a barrier property against oxygen and hydrogen, such as aluminum oxide, hafnium oxide, or gallium oxide. Silicon nitride formed by a CVD method may also be used.

[0228] The inclusion of the barrier layer can broaden the range of material choices for the conductor 542. For example, a material that has low oxidation resistance but high conductivity, such as tungsten or aluminum, can be used for the conductor 542. In addition, for example, a conductor that is easy to form or process can be used.

[0229] The insulator 550 functions as a gate insulating film. The insulator 550 is preferably provided in an opening in the insulator 580 with the oxide 530c and the insulator 574 interposed therebetween.

[0230] As transistors become smaller and more highly integrated, problems such as leakage current may occur due to the thinning of the gate insulating film. In this case, the insulator 550 may have a laminated structure. By making the insulator functioning as the gate insulating film a laminated structure of a high-k material and a thermally stable material, it is possible to reduce the gate potential during transistor operation while maintaining the physical film thickness. In addition, a laminated structure that is thermally stable and has a high relative dielectric constant can be obtained.

[0231] The conductor 560 functioning as a gate electrode has a conductor 560a and a conductor 560b on the conductor 560a. The conductor 560a is preferably made of a conductive material having a function of suppressing the diffusion of impurities such as hydrogen atoms, hydrogen molecules, water molecules, and copper atoms. Alternatively, it is preferably made of a conductive material having a function of suppressing the diffusion of oxygen (for example, at least one of oxygen atoms, oxygen molecules, and the like). Note that in this specification, the function of suppressing the diffusion of impurities or oxygen refers to the function of suppressing the diffusion of any one or all of the above impurities and the above oxygen.

[0232] The conductor 560a has a function of suppressing oxygen diffusion, which improves the material selectivity of the conductor 560b. In other words, the presence of the conductor 560a suppresses oxidation of the conductor 560b, thereby preventing a decrease in electrical conductivity.

[0233] As the conductive material having the function of suppressing the diffusion of oxygen, for example, tantalum, tantalum nitride, ruthenium, or ruthenium oxide is preferably used. In addition, an oxide semiconductor that can be used as the oxide 530 can be used as the conductor 560a. In this case, the electric resistance value of the conductor 560a can be reduced by forming the conductor 560b by a sputtering method. The conductor 560a with the reduced electric resistance value can be called an OC (Oxide Conductor) electrode.

[0234] Conductor 560b is preferably made of a conductive material containing tungsten, copper, or aluminum as a main component. Conductor 560 functions as wiring, so it is preferable to use a conductive material with high conductivity for conductor 560b. Conductor 560b may have a layered structure, for example, a layered structure of titanium, titanium nitride, and the conductive material.

[0235] An insulator 574 is disposed between the insulator 580 and the transistor 510A. The insulator 574 may be an insulating material that has a function of suppressing diffusion of impurities such as water or hydrogen, and oxygen. For example, aluminum oxide or hafnium oxide may be preferably used. In addition, for example, a metal oxide such as magnesium oxide, gallium oxide, germanium oxide, yttrium oxide, zirconium oxide, lanthanum oxide, neodymium oxide, or tantalum oxide, silicon nitride oxide, or silicon nitride may be used.

[0236] The insulator 574 can prevent impurities such as water and hydrogen contained in the insulator 580 from diffusing to the oxide 530b through the oxide 530c and the insulator 550. The insulator 574 can also prevent the conductor 560 from being oxidized by excess oxygen contained in the insulator 580.

[0237] Insulator 580, insulator 582, and insulator 584 function as interlayer films.

[0238] Like the insulator 514, the insulator 582 preferably functions as a barrier insulating film that prevents impurities such as water or hydrogen from entering the transistor 510A from the outside.

[0239] Similarly to the insulator 516, the insulators 580 and 584 preferably have a lower dielectric constant than the insulator 582. By using a material with a low dielectric constant as an interlayer film, parasitic capacitance between wirings can be reduced.

[0240] Additionally, transistor 510A may be electrically connected to other structures through plugs or wiring, such as conductor 546 embedded in insulator 580, insulator 582, and insulator 584.

[0241] The material of the conductor 546 can be a single layer or a stack of conductive materials such as metal materials, alloy materials, metal nitride materials, or metal oxide materials. For example, it is preferable to use a high melting point material such as tungsten or molybdenum that has both heat resistance and conductivity. Alternatively, it is preferable to form the conductor 546 from a low resistance conductive material such as aluminum or copper. By using a low resistance conductive material, the wiring resistance can be reduced.

[0242] For example, the conductor 546 can be formed by using a layered structure of tantalum nitride, a conductor having barrier properties against hydrogen and oxygen, and tungsten, which has high conductivity, thereby suppressing the diffusion of impurities from the outside while maintaining the conductivity of the wiring.

[0243] With the above structure, a semiconductor device including a transistor having an oxide semiconductor with high on-state current can be provided. Alternatively, a semiconductor device including a transistor having an oxide semiconductor with low off-state current can be provided. Alternatively, a semiconductor device including a transistor having an oxide semiconductor with high withstand voltage between the source and drain can be provided. Alternatively, a semiconductor device in which fluctuation in electrical characteristics is suppressed, which has stable electrical characteristics and improved reliability can be provided.

[0244] <Transistor structure example 2> An example of the structure of a transistor 510B will be described with reference to Figures 8(A), (B), and (C). Figure 8(A) is a top view of the transistor 510B. Figure 8(B) is a cross-sectional view of a portion indicated by dashed line L1-L2 in Figure 8(A). Figure 8(C) is a cross-sectional view of a portion indicated by dashed line W1-W2 in Figure 8(A). Note that in the top view of Figure 8(A), some elements are omitted for clarity.

[0245] The transistor 510B is a modified example of the transistor 510A. Therefore, in order to avoid repetition of the description, the following description will mainly focus on the differences from the transistor 510A.

[0246] The transistor 510B has a region in which the conductor 542 (the conductor 542a and the conductor 542b) overlaps with the oxide 530c, the insulator 550, and the conductor 560. With this structure, a transistor with high on-state current can be provided. In addition, a transistor with high controllability can be provided.

[0247] The conductor 560 functioning as a gate electrode has a conductor 560a and a conductor 560b on the conductor 560a. The conductor 560a is preferably made of a conductive material having a function of suppressing the diffusion of impurities such as hydrogen atoms, hydrogen molecules, water molecules, and copper atoms. Alternatively, it is preferably made of a conductive material having a function of suppressing the diffusion of oxygen (for example, at least one of oxygen atoms, oxygen molecules, and the like).

[0248] The conductor 560a has a function of suppressing oxygen diffusion, which improves the material selectivity of the conductor 560b. In other words, the presence of the conductor 560a suppresses oxidation of the conductor 560b, thereby preventing a decrease in electrical conductivity.

[0249] It is preferable to provide an insulator 574 so as to cover the top surface and side surface of the conductor 560, the side surface of the insulator 550, and the side surface of the oxide 530c. Note that the insulator 574 may be made of an insulating material having a function of suppressing the diffusion of impurities such as water or hydrogen, and oxygen. For example, it is preferable to use aluminum oxide or hafnium oxide. In addition, for example, metal oxides such as magnesium oxide, gallium oxide, germanium oxide, yttrium oxide, zirconium oxide, lanthanum oxide, neodymium oxide, or tantalum oxide, silicon nitride oxide, or silicon nitride may also be used.

[0250] Providing the insulator 574 can suppress oxidation of the conductor 560. Furthermore, providing the insulator 574 can suppress diffusion of impurities such as water and hydrogen contained in the insulator 580 to the transistor 510B.

[0251] Furthermore, an insulator 576 (insulator 576a and insulator 576b) having barrier properties may be disposed between the conductor 546 and the insulator 580. Providing the insulator 576 can prevent oxygen in the insulator 580 from reacting with the conductor 546 and oxidizing the conductor 546.

[0252] Furthermore, by providing the insulator 576 having a barrier property, the range of materials that can be selected for the conductor used for the plug or wiring can be expanded. For example, by using a metal material that has a property of absorbing oxygen and has high conductivity for the conductor 546, a semiconductor device with low power consumption can be provided. Specifically, a material that has low oxidation resistance but high conductivity, such as tungsten or aluminum, can be used. Also, for example, a conductor that is easy to form or process can be used.

[0253] <Transistor structure example 3> An example of the structure of a transistor 510C will be described with reference to Figures 9(A), (B) and (C). Figure 9(A) is a top view of the transistor 510C. Figure 9(B) is a cross-sectional view of a portion indicated by dashed line L1-L2 in Figure 9(A). Figure 9(C) is a cross-sectional view of a portion indicated by dashed line W1-W2 in Figure 9(A). Note that in the top view of Figure 9(A), some elements are omitted for clarity.

[0254] The transistor 510C is a modified example of the transistor 510A. Therefore, in order to avoid repetition of the description, the following description will mainly focus on the differences from the transistor 510A.

[0255] 9, a conductor 547a is disposed between a conductor 542a and an oxide 530b, and a conductor 547b is disposed between a conductor 542b and an oxide 530b. Here, the conductor 542a (conductor 542b) extends beyond the upper surface of the conductor 547a (conductor 547b) and the side surface on the conductor 560 side, and has a region in contact with the upper surface of the oxide 530b. Here, the conductor 547 may be any conductor that can be used for the conductor 542. Furthermore, the film thickness of the conductor 547 is preferably at least thicker than that of the conductor 542.

[0256] 9 has the above-described structure, the conductor 542 can be closer to the conductor 560 than the transistor 510A. Alternatively, the ends of the conductor 542a and the conductor 542b can overlap with the conductor 560. This can shorten the effective channel length of the transistor 510C, and improve the on-state current and frequency characteristics.

[0257] The conductor 547a (conductor 547b) is preferably provided so as to overlap the conductor 542a (conductor 542b). With this configuration, the conductor 547a (conductor 547b) functions as a stopper in etching to form an opening in which the conductor 546a (conductor 546b) is to be embedded, thereby preventing the oxide 530b from being overetched.

[0258] 9 may have a structure in which an insulator 545 is disposed on and in contact with the insulator 544. The insulator 544 preferably functions as a barrier insulating film that prevents impurities such as water or hydrogen or excess oxygen from entering the transistor 510C from the insulator 580. The insulator 545 can be any insulator that can be used for the insulator 544. The insulator 544 may be a nitride insulator such as aluminum nitride, aluminum titanium nitride, titanium nitride, silicon nitride, or silicon nitride oxide.

[0259] <Transistor structure example 4> A structural example of a transistor 510D will be described with reference to Figures 10(A), (B), and (C). Figure 10(A) is a top view of the transistor 510D. Figure 10(B) is a cross-sectional view of a portion indicated by dashed line L1-L2 in Figure 10(A). Figure 10(C) is a cross-sectional view of a portion indicated by dashed line W1-W2 in Figure 10(A). Note that in the top view of Figure 10(A), some elements are omitted for clarity.

[0260] The transistor 510D is a variation of the transistor described above, and therefore, in order to avoid repetition of the description, the differences from the transistor described above will be mainly described.

[0261] 10A to 10C, an insulator 550 is provided over the oxide 530c, and a metal oxide 552 is provided over the insulator 550. A conductor 560 is provided over the metal oxide 552, and an insulator 570 is provided over the conductor 560. An insulator 571 is provided over the insulator 570.

[0262] The metal oxide 552 preferably has a function of suppressing oxygen diffusion. By providing the metal oxide 552, which suppresses oxygen diffusion, between the insulator 550 and the conductor 560, the diffusion of oxygen to the conductor 560 is suppressed. That is, a decrease in the amount of oxygen supplied to the oxide 530 can be suppressed. In addition, oxidation of the conductor 560 by oxygen can be suppressed.

[0263] Note that the metal oxide 552 may function as a part of the gate electrode. For example, an oxide semiconductor that can be used as the oxide 530 can be used as the metal oxide 552. In that case, by forming the conductor 560 by a sputtering method, the electric resistance value of the metal oxide 552 can be reduced to form a conductive layer. This can be called an OC (Oxide Conductor) electrode.

[0264] Furthermore, the metal oxide 552 may function as a part of the gate insulating film. Therefore, when silicon oxide or silicon oxynitride is used for the insulator 550, it is preferable to use a metal oxide that is a high-k material with a high relative dielectric constant for the metal oxide 552. By using such a stacked structure, a stacked structure that is stable against heat and has a high relative dielectric constant can be obtained. Therefore, it is possible to reduce the gate potential applied during transistor operation while maintaining the physical film thickness. Also, it is possible to reduce the equivalent oxide thickness (EOT) of the insulating layer that functions as a gate insulating film.

[0265] Although the metal oxide 552 in the transistor 510D is shown as a single layer, it may have a stacked structure of two or more layers. For example, a metal oxide functioning as part of a gate electrode and a metal oxide functioning as part of a gate insulating film may be stacked.

[0266] When the metal oxide 552 functions as a gate electrode, the on-state current of the transistor 510D can be improved without weakening the influence of the electric field from the conductor 560. Alternatively, when the metal oxide 552 functions as a gate insulating film, the physical thickness of the insulator 550 and the metal oxide 552 can maintain a distance between the conductor 560 and the oxide 530, thereby suppressing leakage current between the conductor 560 and the oxide 530. Therefore, by providing a stacked structure of the insulator 550 and the metal oxide 552, the physical distance between the conductor 560 and the oxide 530 and the electric field strength applied from the conductor 560 to the oxide 530 can be easily and appropriately adjusted.

[0267] Specifically, an oxide semiconductor that can be used for the oxide 530 can be reduced in resistance to be used as the metal oxide 552. Alternatively, a metal oxide containing one or more elements selected from hafnium, aluminum, gallium, yttrium, zirconium, tungsten, titanium, tantalum, nickel, germanium, magnesium, and the like can be used.

[0268] In particular, it is preferable to use an insulating layer containing an oxide of either or both of aluminum and hafnium, such as aluminum oxide, hafnium oxide, or an oxide containing aluminum and hafnium (hafnium aluminate). In particular, hafnium aluminate has higher heat resistance than a hafnium oxide film. Therefore, it is preferable because it is less likely to crystallize in a heat treatment in a later process. Note that the metal oxide 552 is not an essential component. It may be appropriately designed depending on the desired transistor characteristics.

[0269] The insulator 570 may be made of an insulating material that has a function of suppressing the permeation of impurities such as water or hydrogen, and oxygen. For example, it is preferable to use aluminum oxide or hafnium oxide. This can suppress the conductor 560 from being oxidized by oxygen from above the insulator 570. In addition, impurities such as water or hydrogen from above the insulator 570 can be suppressed from being mixed into the oxide 530 through the conductor 560 and the insulator 550.

[0270] The insulator 571 functions as a hard mask. By providing the insulator 571, when the conductor 560 is processed, the side surface of the conductor 560 can be approximately vertical, specifically, the angle between the side surface of the conductor 560 and the substrate surface can be set to 75 degrees or more and 100 degrees or less, preferably 80 degrees or more and 95 degrees or less.

[0271] Note that the insulator 571 may also function as a barrier layer by using an insulating material that has a function of suppressing permeation of impurities such as water or hydrogen and oxygen. In that case, the insulator 570 is not necessarily provided.

[0272] Using insulator 571 as a hard mask, portions of insulator 570, conductor 560, metal oxide 552, insulator 550, and oxide 530c can be selectively removed to roughly align their sides and expose a portion of the surface of oxide 530b.

[0273] Transistor 510D also has regions 531a and 531b on a portion of the exposed oxide 530b surface, with either region 531a or region 531b functioning as a source region and the other functioning as a drain region.

[0274] The formation of the regions 531a and 531b can be achieved by introducing an impurity element such as phosphorus or boron into the exposed surface of the oxide 530b by, for example, ion implantation, ion doping, plasma immersion ion implantation, plasma treatment, etc. In this embodiment and the like, the term "impurity element" refers to an element other than the main component element.

[0275] In addition, a metal film can be formed after exposing a portion of the surface of oxide 530b, and then heat-treated to diffuse elements contained in the metal film into oxide 530b, thereby forming regions 531a and 531b.

[0276] The region of the oxide 530b into which the impurity element has been introduced has a reduced electrical resistivity, and therefore the region 531a and the region 531b are sometimes referred to as "impurity region" or "low resistance region."

[0277] By using the insulator 571 and / or the conductor 560 as a mask, the regions 531a and 531b can be formed in a self-aligned manner. Therefore, the regions 531a and / or 531b do not overlap with the conductor 560, and parasitic capacitance can be reduced. In addition, an offset region is not formed between the channel formation region and the source / drain region (region 531a or region 531b). By forming the regions 531a and 531b in a self-aligned manner, it is possible to realize an increase in on-current, a reduction in threshold voltage, an improvement in operating frequency, and the like.

[0278] In order to further reduce the off-state current, an offset region may be provided between the channel formation region and the source / drain region. The offset region is a region having high electrical resistivity, into which the above-described impurity element is not introduced. The offset region can be formed by introducing the above-described impurity element after the formation of the insulator 575. In this case, the insulator 575 also functions as a mask, similar to the insulator 571. Therefore, the impurity element is not introduced into the region of the oxide 530b that overlaps with the insulator 575, and the electrical resistivity of the region can be kept high.

[0279] The transistor 510D also has an insulator 575 on the side surfaces of the insulator 570, the conductor 560, the metal oxide 552, the insulator 550, and the oxide 530c. The insulator 575 is preferably an insulator with a low dielectric constant. For example, silicon oxide, silicon oxynitride, silicon nitride oxide, silicon nitride, silicon oxide to which fluorine has been added, silicon oxide to which carbon has been added, silicon oxide to which carbon and nitrogen have been added, silicon oxide having voids, or a resin is preferable. In particular, when silicon oxide, silicon oxynitride, silicon nitride oxide, or silicon oxide having voids is used for the insulator 575, it is preferable because an excess oxygen region can be easily formed in the insulator 575 in a later step. Silicon oxide and silicon oxynitride are preferable because they are thermally stable. The insulator 575 also preferably has a function of diffusing oxygen.

[0280] The transistor 510D further includes an insulator 575 and an insulator 574 over the oxide 530. The insulator 574 is preferably formed by a sputtering method. By using a sputtering method, an insulator containing few impurities such as water or hydrogen can be formed. For example, aluminum oxide is preferably used as the insulator 574.

[0281] Note that an oxide film formed by a sputtering method may extract hydrogen from a structure to be deposited. Therefore, the insulator 574 absorbs hydrogen and water from the oxide 530 and the insulator 575, thereby reducing the hydrogen concentrations in the oxide 530 and the insulator 575.

[0282] <Transistor structure example 5> A structural example of a transistor 510E will be described with reference to Figures 11(A) to 11(C). Figure 11(A) is a top view of the transistor 510E. Figure 11(B) is a cross-sectional view of a portion indicated by dashed dotted line L1-L2 in Figure 11(A). Figure 11(C) is a cross-sectional view of a portion indicated by dashed dotted line W1-W2 in Figure 11(A). Note that in the top view of Figure 11(A), some elements are omitted for clarity.

[0283] The transistor 510E is a variation of the transistor described above, and therefore, in order to avoid repetition of description, the following description will focus mainly on the differences from the transistor described above.

[0284] 11A to 11C, the conductor 542 is not provided, and a part of the exposed surface of the oxide 530b has a region 531a and a region 531b. One of the region 531a and the region 531b functions as a source region, and the other functions as a drain region. In addition, an insulator 573 is provided between the oxide 530b and the insulator 574.

[0285] 11B, a region 531 (regions 531a and 531b) is a region in which the following elements are added to the oxide 530b: The region 531 can be formed by using, for example, a dummy gate.

[0286] Specifically, a dummy gate is provided on the oxide 530b, and the dummy gate is used as a mask to add an element that reduces the resistance of the oxide 530b. That is, the element is added to a region where the oxide 530b does not overlap with the dummy gate, forming the region 531. The element can be added by an ion implantation method in which an ionized source gas is added after being mass-separated, an ion doping method in which an ionized source gas is added without being mass-separated, a plasma immersion ion implantation method, or the like.

[0287] Representative elements that reduce the resistance of the oxide 530b include boron and phosphorus. Hydrogen, carbon, nitrogen, fluorine, sulfur, chlorine, titanium, rare gases, and the like may also be used. Representative examples of rare gases include helium, neon, argon, krypton, and xenon. The concentration of the element may be measured using secondary ion mass spectrometry (SIMS) or the like.

[0288] In particular, boron and phosphorus are preferable because they allow the use of equipment from manufacturing lines for amorphous silicon or low-temperature polysilicon, and existing facilities can be repurposed, allowing capital investment to be reduced.

[0289] Subsequently, an insulating film to be the insulator 573 and an insulating film to be the insulator 574 may be formed over the oxide 530b and the dummy gate. By stacking the insulating film to be the insulator 573 and the insulating film to be the insulator 574, a region in which the region 531 overlaps with the oxide 530c and the insulator 550 can be provided.

[0290] Specifically, an insulating film to be the insulator 580 is provided on an insulating film to be the insulator 574, and then a CMP (Chemical Mechanical Polishing) process is performed on the insulating film to be the insulator 580 to remove a part of the insulating film to be the insulator 580 and expose the dummy gate. Then, when removing the dummy gate, a part of the insulator 573 in contact with the dummy gate may also be removed. Therefore, the insulator 574 and the insulator 573 are exposed on the side of the opening provided in the insulator 580, and a part of the region 531 provided in the oxide 530b is exposed on the bottom of the opening. Next, an oxide film to be the oxide 530c, an insulating film to be the insulator 550, and a conductive film to be the conductor 560 are sequentially formed in the opening, and then the oxide film to be the oxide 530c, the insulating film to be the insulator 550, and a conductive film to be the conductor 560 are removed by a CMP process or the like until the insulator 580 is exposed, thereby forming the transistor shown in FIG. 11.

[0291] Note that the insulators 573 and 574 are not essential components and may be appropriately designed depending on desired transistor characteristics.

[0292] The transistor shown in FIG. 11 can be an existing device and does not include the conductor 542, which leads to cost reduction.

[0293] <Transistor structure example 6> 5 and 6, a structure example in which the conductor 560 functioning as a gate is formed inside the opening of the insulator 580 has been described, but for example, a structure in which the insulator is provided above the conductor can also be used. Structural examples of such a transistor are shown in FIGS.

[0294] Fig. 12A is a top view of a transistor, and Fig. 12B is a perspective view of the transistor. Fig. 13A shows a cross-sectional view along X1-X2 in Fig. 12A, and Fig. 13B shows a cross-sectional view along Y1-Y2 in Fig. 12A.

[0295] 12 and 13 includes an oxide semiconductor S, an insulator FGI having a function as a gate insulating film, a conductor FGE having a function as a front gate, and a conductor WE having a function as a wiring. The conductor PE functions as a plug for connecting the conductor WE to the oxide S or the conductor FGE. Here, an example is shown in which the oxide semiconductor S is composed of three layers of oxides S1, S2, and S3.

[0296] Note that this embodiment mode can be implemented in appropriate combination with other embodiment modes described in this specification.

[0297] (Embodiment 4) In this embodiment, a structure of a metal oxide that can be used for the OS transistor described in the above embodiment will be described.

[0298] <Metal oxide composition> In this specification, etc., they may be referred to as c-axis aligned crystal (CAAC) and cloud-aligned composite (CAC). Note that CAAC represents an example of a crystal structure, and CAC represents an example of a function or material configuration.

[0299] CAC-OS or CAC-metal oxide has a conductive function in a part of the material and an insulating function in a part of the material, and has a function as a semiconductor as a whole. When CAC-OS or CAC-metal oxide is used in a channel formation region of a transistor, the conductive function is a function of flowing electrons (or holes) that become carriers, and the insulating function is a function of not flowing electrons that become carriers. By making the conductive function and the insulating function act complementarily, a switching function (on / off function) can be imparted to CAC-OS or CAC-metal oxide. By separating the respective functions in CAC-OS or CAC-metal oxide, both functions can be maximized.

[0300] Moreover, the CAC-OS or CAC-metal oxide has a conductive region and an insulating region. The conductive region has the above-mentioned conductive function, and the insulating region has the above-mentioned insulating function. In addition, in the material, the conductive region and the insulating region may be separated at the nanoparticle level. In addition, the conductive region and the insulating region may be unevenly distributed in the material. In addition, the conductive region may be observed to be connected in a cloud shape with a blurred periphery.

[0301] In addition, in the CAC-OS or CAC-metal oxide, the conductive regions and the insulating regions may each be dispersed in the material with a size of 0.5 nm to 10 nm, preferably 0.5 nm to 3 nm.

[0302] In addition, the CAC-OS or CAC-metal oxide is composed of components having different band gaps. For example, the CAC-OS or CAC-metal oxide is composed of a component having a wide gap due to an insulating region and a component having a narrow gap due to a conductive region. In this configuration, when carriers are caused to flow, the carriers mainly flow in the component having the narrow gap. In addition, the component having the narrow gap acts complementarily on the component having the wide gap, and carriers also flow in the component having the wide gap in conjunction with the component having the narrow gap. Therefore, when the above CAC-OS or CAC-metal oxide is used in the channel formation region of a transistor, a high current driving force in the on state of the transistor, that is, a large on-current and a high field effect mobility can be obtained.

[0303] That is, CAC-OS or CAC-metal oxide can also be called a matrix composite or a metal matrix composite.

[0304] <Metal oxide structure> Oxide semiconductors are classified into single-crystal oxide semiconductors and non-single-crystal oxide semiconductors other than those. Examples of non-single-crystal oxide semiconductors include c-axis aligned crystalline oxide semiconductors (CAAC-OS), polycrystalline oxide semiconductors, nanocrystalline oxide semiconductors (nc-OS), amorphous-like oxide semiconductors (a-like OS), and amorphous oxide semiconductors.

[0305] It is preferable to use a thin film with high crystallinity as the oxide semiconductor used as the semiconductor of the transistor. By using the thin film, the stability or reliability of the transistor can be improved. Examples of the thin film include a thin film of a single crystal oxide semiconductor or a thin film of a polycrystalline oxide semiconductor. However, a high-temperature or laser heating process is required to form a thin film of a single crystal oxide semiconductor or a thin film of a polycrystalline oxide semiconductor on a substrate. Therefore, the cost of the manufacturing process increases, and the throughput also decreases.

[0306] In 2009, the discovery of In-Ga-Zn oxide with a CAAC structure (referred to as CAAC-IGZO) was reported in Non-Patent Documents 1 and 2. It was reported that CAAC-IGZO has a c-axis orientation, no clearly visible crystal grain boundaries, and can be formed on a substrate at low temperatures. Furthermore, it was reported that transistors using CAAC-IGZO have excellent electrical characteristics and reliability.

[0307] In 2013, In-Ga-Zn oxide with an nc structure (called nc-IGZO) was discovered (see Non-Patent Document 3). It was reported that nc-IGZO has periodic atomic arrangement in minute regions (e.g., regions of 1 nm to 3 nm), and no regularity is observed in the crystal orientation between different regions.

[0308] Non-Patent Documents 4 and 5 show the transition of the average crystal size by electron beam irradiation for each of the above CAAC-IGZO, nc-IGZO, and low-crystalline IGZO thin films. In the low-crystalline IGZO thin film, crystalline IGZO of about 1 nm is observed even before the electron beam irradiation. Therefore, it is reported here that the presence of a completely amorphous structure could not be confirmed in IGZO. Furthermore, it is shown that the CAAC-IGZO thin film and the nc-IGZO thin film have high stability against electron beam irradiation compared to the low-crystalline IGZO thin film. Therefore, it is preferable to use the CAAC-IGZO thin film or the nc-IGZO thin film as a semiconductor for a transistor.

[0309] CAAC-OS has a c-axis orientation and a distorted crystal structure in which multiple nanocrystals are connected in the ab-plane direction. The distortion refers to a portion where the lattice orientation changes between a region with a uniform lattice arrangement and a region with a different uniform lattice arrangement in the region where multiple nanocrystals are connected.

[0310] Nanocrystals are basically hexagonal, but are not limited to regular hexagonal shapes and may be non-regular hexagonal. In addition, the lattice arrangement of the distortion may be pentagonal, heptagonal, or other shapes. In the CAAC-OS, no clear grain boundary can be confirmed even near the distortion. In other words, it is found that the formation of grain boundaries is suppressed by the distortion of the lattice arrangement. This is thought to be because the CAAC-OS can tolerate distortion due to the lack of dense arrangement of oxygen atoms in the ab-plane direction and the change in the bond distance between atoms due to the substitution of metal elements.

[0311] CAAC-OS also tends to have a layered crystal structure (also referred to as a layered structure) in which a layer containing indium and oxygen (hereinafter, In layer) and a layer containing element M, zinc, and oxygen (hereinafter, (M, Zn) layer) are stacked. Note that indium and element M can be substituted for each other, and when element M in an (M, Zn) layer is substituted for indium, it can also be expressed as an (In, M, Zn) layer. When indium in an In layer is substituted for element M, it can also be expressed as an (In, M) layer.

[0312] CAAC-OS is an oxide semiconductor with high crystallinity. On the other hand, since no clear crystal grain boundaries can be identified in CAAC-OS, it can be said that a decrease in electron mobility due to crystal grain boundaries is unlikely to occur. In addition, since the crystallinity of an oxide semiconductor can be decreased by the inclusion of impurities or the generation of defects, CAAC-OS can be said to be an oxide semiconductor with few impurities and defects (such as oxygen vacancies). Therefore, an oxide semiconductor having CAAC-OS has stable physical properties. Therefore, an oxide semiconductor having CAAC-OS is resistant to heat and has high reliability. In addition, CAAC-OS is stable against high temperatures (so-called thermal budget) in the manufacturing process. Therefore, the use of CAAC-OS in an OS transistor can increase the degree of freedom in the manufacturing process.

[0313] The nc-OS has periodic atomic arrangement in a microscopic region (for example, a region of 1 nm to 10 nm, particularly a region of 1 nm to 3 nm). In addition, the nc-OS does not show regularity in the crystal orientation between different nanocrystals. Therefore, no orientation is seen throughout the film. Therefore, depending on the analysis method, the nc-OS may be indistinguishable from an a-like OS or an amorphous oxide semiconductor.

[0314] The a-like OS is an oxide semiconductor having a structure between the nc-OS and an amorphous oxide semiconductor. The a-like OS has a void or low-density region. That is, the a-like OS has lower crystallinity than the nc-OS and CAAC-OS.

[0315] Oxide semiconductors have a variety of structures and each structure has different characteristics. The oxide semiconductor of one embodiment of the present invention may include two or more of an amorphous oxide semiconductor, a polycrystalline oxide semiconductor, an a-like OS, an nc-OS, and a CAAC-OS.

[0316] <Transistor Having Oxide Semiconductor> Next, the case where the oxide semiconductor is used for a transistor will be described.

[0317] By using the oxide semiconductor for a transistor, a transistor with high field-effect mobility and high reliability can be realized.

[0318] Furthermore, the transistor including the oxide semiconductor has an extremely small leakage current in an off-state. Specifically, the off-state current per 1 μm of the channel width of the transistor is yA / μm (10 -24 Non-Patent Document 6 shows that the leakage current is on the order of A / μm. For example, a low-power consumption CPU that utilizes the low leakage current characteristic of a transistor using an oxide semiconductor has been disclosed (see Non-Patent Document 7).

[0319] In addition, the application of oxide semiconductor transistors to display devices has been reported, taking advantage of the low leakage current characteristic of the transistors (see Non-Patent Document 8). In display devices, the displayed image is switched several tens of times per second. The number of times the image is switched per second is called the refresh rate. The refresh rate is also sometimes called the drive frequency. Such high-speed screen switching, which is difficult for the human eye to perceive, is considered to be the cause of eye fatigue. Therefore, it has been proposed to reduce the refresh rate of the display device to reduce the number of times the image is rewritten. In addition, it is possible to reduce the power consumption of the display device by driving with a reduced refresh rate. This type of driving method is called idling stop (IDS) driving.

[0320] In addition, it is preferable to use an oxide semiconductor with low carrier density for the transistor. In order to reduce the carrier density of an oxide semiconductor film, the impurity concentration in the oxide semiconductor film may be reduced to reduce the density of defect states. In this specification and the like, a semiconductor having a low impurity concentration and a low density of defect states is referred to as being highly pure intrinsic or substantially highly pure intrinsic. For example, an oxide semiconductor having a carrier density of 8×10 11 / cm 3 Less than 1 x 10 11 / cm 3 less than 1×10 10 / cm 3 Less than 1 x 10 -9 / cm 3 That should be enough.

[0321] In addition, a highly purified intrinsic or substantially highly purified intrinsic oxide semiconductor film has a low density of defect states, and therefore the density of trap states might also be low.

[0322] In addition, charges trapped in the trap states of an oxide semiconductor take a long time to disappear and may behave as if they are fixed charges. Therefore, a transistor in which a channel formation region is formed in an oxide semiconductor with a high density of trap states may have unstable electrical characteristics.

[0323] Therefore, in order to stabilize the electrical characteristics of a transistor, it is effective to reduce the impurity concentration in the oxide semiconductor. In order to reduce the impurity concentration in the oxide semiconductor, it is preferable to also reduce the impurity concentration in a nearby film. Examples of impurities include hydrogen, nitrogen, alkali metals, alkaline earth metals, iron, nickel, silicon, and the like.

[0324] <Impurities> Here, the influence of each impurity in an oxide semiconductor will be described.

[0325] When an oxide semiconductor contains silicon or carbon, which is one of the group 14 elements, defect levels are formed in the oxide semiconductor. For this reason, the concentrations of silicon or carbon in the oxide semiconductor and those near the interface with the oxide semiconductor (concentrations obtained by secondary ion mass spectrometry (SIMS)) are calculated as 2×10 18 atoms / cm 3 Less than or equal to 2 x 10 17 atoms / cm 3 The following applies.

[0326] Furthermore, when an oxide semiconductor contains an alkali metal or an alkaline earth metal, defect levels are formed and carriers are generated in some cases. Therefore, a transistor using an oxide semiconductor containing an alkali metal or an alkaline earth metal is likely to have normally-on characteristics. For this reason, it is preferable to reduce the concentration of the alkali metal or the alkaline earth metal in the oxide semiconductor. Specifically, when the concentration of the alkali metal or the alkaline earth metal in the oxide semiconductor obtained by SIMS is 1×10 18 atoms / cm 3 Less than or equal to 2 x 10 16 atoms / cm 3 To the following:

[0327] Furthermore, when nitrogen is contained in an oxide semiconductor, electrons serving as carriers are generated, the carrier density increases, and the semiconductor tends to become n-type. As a result, a transistor using an oxide semiconductor containing nitrogen as a semiconductor tends to have normally-on characteristics. Therefore, it is preferable that nitrogen be reduced as much as possible in the oxide semiconductor. For example, the nitrogen concentration in the oxide semiconductor is 5×10 19 atoms / cm 3 Less than 5 x 10 18 atoms / cm 3 Less than or equal to 1×10 18 atoms / cm 3 Less than 5×10, more preferably 17 atoms / cm 3 The following applies.

[0328] Furthermore, hydrogen contained in an oxide semiconductor reacts with oxygen bonded to a metal atom to form water, which may form an oxygen vacancy. When hydrogen enters the oxygen vacancy, electrons serving as carriers may be generated. In addition, some of the hydrogen may bond with oxygen bonded to a metal atom to generate electrons serving as carriers. Therefore, a transistor using an oxide semiconductor containing hydrogen is likely to have normally-on characteristics. For this reason, it is preferable to reduce hydrogen in the oxide semiconductor as much as possible. Specifically, when the hydrogen concentration in an oxide semiconductor measured by SIMS is 1×10 20 atoms / cm 3 Less than 1 x 10 19 atoms / cm 3 less than 5×10 18 atoms / cm 3 less than 1×10 18 atoms / cm 3 Less than.

[0329] When an oxide semiconductor in which impurities are sufficiently reduced is used for a channel formation region of a transistor, stable electrical characteristics can be obtained.

[0330] The discovery of the CAAC structure and the nc structure has contributed to improving the electrical characteristics and reliability of transistors using oxide semiconductors having the CAAC structure or the nc structure, as well as reducing the cost and improving the throughput of the manufacturing process. In addition, research is being conducted on the application of the transistor to display devices and LSIs, taking advantage of the low leakage current of the transistor.

[0331] Note that this embodiment mode can be implemented in appropriate combination with other embodiment modes described in this specification.

[0332] (Embodiment 5) In this embodiment, an example of an electronic device including a secondary battery and the anomaly detection system described in the above embodiment will be described.

[0333] For example, the anomaly detection system 100 (or the anomaly detection system 110) can be used in an information terminal 5500 (see FIG. 14A). The information terminal 5500 is a mobile phone (smartphone). The information terminal 5500 has a housing 5510 and a display unit 5511. As an input interface, a touch panel is provided in the display unit 5511, and buttons are provided in the housing 5510.

[0334] For example, the anomaly detection system 100 (or the anomaly detection system 110) can be used in a notebook personal computer 5400 (see FIG. 14B). The personal computer 5400 includes a display unit 5401, a housing 5402, a touch pad 5403, a connection port 5404, and the like.

[0335] The touchpad 5403 functions as an input means such as a pointing device or a pen tablet, and can be operated with a finger, a stylus, or the like. A display element is built into the touchpad 5403. As shown in Fig. 14(B), by displaying input keys 5405 on the surface of the touchpad 5403, the touchpad 5403 can be used as a keyboard. A vibration module may be built into the touchpad 5403 to realize a tactile sensation by vibration when the input keys 5405 are touched.

[0336] For example, the anomaly detection system 100 (or the anomaly detection system 110) can be used in a video camera 5300 (see FIG. 14(C)). The video camera 5300 has a first housing 5301, a second housing 5302, a display unit 5303, operation buttons 5304, a lens 5305, a connection unit 5306, and the like. The operation buttons 5304 and the lens 5305 are provided in the first housing 5301, and the display unit 5303 is provided in the second housing 5302.

[0337] For example, the anomaly detection system 100 (or the anomaly detection system 110) can be used in a robot 5900 (see FIG. 14(D)). The robot 5900 includes a computing device 5910, an illuminance sensor 5901, a microphone 5902, an upper camera 5903, a speaker 5904, a display 5905, a lower camera 5906, an obstacle sensor 5907, a moving mechanism 5908, and the like.

[0338] The upper camera 5903 and the lower camera 5906 have a function of capturing images of the surroundings of the robot 5900. Furthermore, the obstacle sensor 5907 can detect the presence or absence of an obstacle when the robot 5900 moves using the moving mechanism 5908. The robot 5900 can recognize the surrounding environment using the upper camera 5903, the lower camera 5906, and the obstacle sensor 5907, and move safely.

[0339] For example, the anomaly detection system 100 (or the anomaly detection system 110) can be used in a cleaning robot 5100 (see FIG. 15). The cleaning robot 5100 has a display 5101 arranged on the top surface, a plurality of cameras 5102 arranged on the side surface, a brush 5103, an operation button 5104, and the like.

[0340] Although not shown, the cleaning robot 5100 is provided with tires, a suction port, and the like on its underside. The cleaning robot 5100 also includes various sensors such as an infrared sensor, an ultrasonic sensor, an acceleration sensor, a piezoelectric sensor, an optical sensor, and a gyro sensor. The cleaning robot 5100 also includes wireless communication means.

[0341] The cleaning robot 5100 can move by itself, detect dust 5120, and suck up the dust 5120 from a suction port provided on the bottom surface. The cleaning robot 5100 can also analyze an image captured by a camera 5102 to determine the presence or absence of an obstacle such as a wall, furniture, or a step. If an object that may become entangled in the brush 5103, such as a wire, is detected by image analysis, the rotation of the brush 5103 can be stopped. The display 5101 can display the amount of charge in a secondary battery (also called a battery), the amount of dust sucked up, and the like.

[0342] The cleaning robot 5100 can communicate with an information terminal 5140 such as a smartphone. Images captured by the camera 5102 can be displayed on the information terminal 5140. Therefore, the owner of the cleaning robot 5100 can know the state of the room even when he or she is away from home.

[0343] For example, the anomaly detection system 100 (or the anomaly detection system 110) can be used in an electric bicycle 5700 (see FIG. 16(A)). The electric bicycle 5700 has a power storage system 5702 and the like. The power storage system 5702 supplies electricity to a motor that assists the rider of the electric bicycle 5700, allowing the rider to pedal with less effort. The power storage system 5702 is portable, and is shown removed from the electric bicycle 5700 in FIG. 16(B).

[0344] A power storage system 5702 includes a plurality of secondary batteries 5701, and a display unit 5703 can display the amount of stored power. The power storage system 5702 includes a control circuit 5704, which is connected to the secondary batteries 5701. As part of the control circuit 5704, the abnormality detection system 100 (or the abnormality detection system 110) described in the above embodiment can be used.

[0345] As described above, the anomaly detection system 100 (or the anomaly detection system 110) described in the above embodiment can be used in various electronic devices having secondary batteries. In recent years, secondary batteries in electronic devices are required to have various performance characteristics such as small size, light weight, high output, high capacity, fast charging, and compatibility with a wide range of environmental temperatures, and these performance characteristics of secondary batteries are factors that determine the attractiveness of electronic devices having secondary batteries. On the other hand, ensuring the safety of secondary batteries is an important issue related to the reliability of electronic devices. By using the anomaly detection system 100 (or the anomaly detection system 110) described in the above embodiment, it is possible to provide electronic devices with high safety.

[0346] Note that this embodiment mode can be implemented in appropriate combination with other embodiment modes described in this specification. [Explanation of symbols]

[0347] C11: Capacitive element:, :N11: Node:, :N12: Node:, :N13: Node:, :R11: Resistive element:, :R12: Strain sensor element:, :S1: Oxide:, :T11: Transistor:, :30: Strain sensor:, :40: Memory:, :50: Comparator:, :60: Oscillation circuit:, :70: Circuit:, :100: Abnormality detection system:, :110: Abnormality detection system:, :200: Secondary battery:, :201: Positive electrode cap:, :202: Battery can:, :203: Positive electrode terminal:, :204: Positive electrode:, :205: Separator:, :206: Negative electrode:, :207: Negative electrode terminal child:,:208:insulating plate:,:209:insulating plate:,:211:PTC element:,:212:safety valve:,:300:transistor:,:311:substrate:,:313:semiconductor region:,:314a:low resistance region:,:314b:low resistance region:,:315:insulator:,:316:conductor:,:320:insulator:,:322:insulator:,:324:insulator:,:326:insulator:,:328:conductor:,:330:conductor:,:350:insulator:,:352:insulator:,:354:insulator:,:356:conductor:,:360:insulator:,:362:insulator:,:364 :Insulator:, :366:Conductor:, :370:Insulator:, :372:Insulator:, :374:Insulator:, :376:Conductor:, :380:Insulator:, :382:Insulator:, :384:Insulator:, :386:Conductor:, :500:Transistor:, :510:Insulator:, :510A:Transistor:, :510B:Transistor:, :510C:Transistor:, :510D:Transistor:, :510E:Transistor:, :511:Insulator:, :512:Insulator:, :514:Insulator:, :516:Insulator:, :518:Conductor:, :520:Insulator: , :522:Insulator:, :524:Insulator:, :530:Oxide:, :530a:Oxide:, :530b:Oxide:, :530c:Oxide:, :531:Region:, :531a:Region:, :531b:Region:, :540a:Conductor:, :540b:Conductor:, :542:Conductor:, :542a:Conductor:, :542b:Conductor:, :543:Region:, :543a:Region:, :543b:Region:, :544:Insulator:, :545:Insulator:, :546:Conductor:, :546a:Conductor:, :546b:Conductor:, :547:Conductor:, :547a:Conductor:,:547b:Conductor:, :548:Conductor:, :550:Insulator:, :552:Metal oxide:, :560:Conductor:, :560a:Conductor:, :560b:Conductor:, :570:Insulator:, :571:Insulator:, :573:Insulator:, :574:Insulator:, :575:Insulator:, :576:Insulator:, :576a:Insulator:, :576b:Insulator:, :580:Insulator:, :581:Insulator:, :582:Insulator:, :584:Insulator:, :586:Insulator:, :600 :Capacitive element:,:610:Conductor:,:612:Conductor:,:620:Conductor:,:630:Insulator:,:650:Insulator:,:900:Secondary battery:,:912:Safety valve:,:930:Housing:,:930a:Housing:,:930b:Housing:,:931:Negative electrode:,:932:Positive electrode:,:933:Separator:,:950:Winding body:,:951:Terminal:,:952:Terminal:,:5100:Cleaning robot:,:5101:Display:,:5102:Camera:,:5103:B :,:5104:Operation button:,:5120:Trash:,:5140:Information terminal:,:5300:Video camera:,:5301:Housing:,:5302:Housing:,:5303:Display unit:,:5304:Operation button:,:5305:Lens:,:5306:Connection unit:,:5400:Personal computer:,:5401:Display unit:,:5402:Housing:,:5403:Touch pad:,:5404:Connection port:,:5405:Input key:,:5500:Information terminal:, :5510:Housing:,:5511:Display unit:,:5700:Electric bicycle:,:5701:Secondary battery:,:5702:Energy storage system:,:5703:Display unit:,:5704:Control circuit:,:5900:Robot:,:5901:Illuminance sensor:,:5902:Microphone:,:5903:Upper camera:,:5904:Speaker:,:5905:Display:,:5906:Lower camera:,:5907:Obstacle sensor:,:5908:Movement mechanism:,:5910:Calculation unit,

Claims

1. A strain sensor; Memory, A comparator and an anomaly detection system comprising: The memory has a function of retaining an analog potential, the comparator has a function of comparing a first potential output by the strain sensor with a second potential stored in the memory, The anomaly detection system outputs an anomaly detection signal when the first potential becomes higher than the second potential.

2. A strain sensor; Memory, A comparator and an anomaly detection system comprising: The memory has a function of retaining an analog potential, the comparator has a function of comparing a first potential output by the strain sensor with a second potential stored in the memory, The anomaly detection system outputs an anomaly detection signal when the first potential becomes lower than the second potential.

Images