Battery protection circuit, power storage device, and electric appliance

Abstract

A battery protection circuit of a novel structure and a power storage device having the same are provided. The battery protection circuit includes a switching circuit for controlling charge and discharge of a battery cell, the switching circuit including a mechanical relay, a first transistor, and a second transistor, the switching circuit having a function of controlling electrical connection between a first terminal and a second terminal, the mechanical relay having a function of interrupting the electrical connection between the first terminal and the second terminal, the first transistor having a function of causing a first current to flow between the first terminal and the second terminal, the second transistor having a function of causing a second current to flow between the first terminal and the second terminal, the first current being larger than the second current.

Description

Technical Field

[0001] One aspect of the present invention relates to a battery protection circuit, a storage device, and an electrical appliance. Background Technology

[0002] Energy storage devices (also known as batteries or secondary batteries) are used in a wide range of applications, from small appliances to automobiles. Energy storage devices typically include battery protection circuits to detect abnormalities during charging and discharging, such as over-discharge, over-charge, overcurrent, or short circuits.

[0003] The battery protection circuit acquires data such as voltage or current to detect abnormalities during charging or discharging. Based on the observed data, the battery protection circuit controls the opening and closing of switches set in the charging or discharging path to prevent overcharging or over-discharging of the battery cell (for example, see Patent Document 1). [Preliminary Technology Documents] [Patent Literature]

[0004] [Patent Document 1] U.S. Patent Application Publication No. 2016-118821 Summary of the Invention The technical problem that the invention aims to solve

[0005] When no current flows through the load, a switch located in the charging or discharging path is preferably positioned to more reliably interrupt the current. Conversely, when current flows through the load, a switch located in the charging or discharging path is preferably positioned to allow a large current to flow.

[0006] One objective of this invention is to provide a novel battery protection circuit, energy storage device, and electrical appliance. Another objective of this invention is to provide a battery protection circuit, energy storage device, and electrical appliance with a novel structure that can both interrupt current and allow large currents to flow.

[0007] Note that the purpose of one aspect of the present invention is not limited to the objectives described above. The objectives listed above do not preclude the existence of other objectives. Furthermore, other objectives are those not mentioned above but will be described in the following description. Those skilled in the art can derive and appropriately extract objectives not mentioned above from the description, drawings, etc. Additionally, one aspect of the present invention achieves at least one of the above objectives and / or other objectives. means of solving technical problems

[0008] One aspect of the present invention is a battery protection circuit, which includes a switching circuit for controlling the charging and discharging of a battery cell. The switching circuit includes a mechanical relay, a first transistor, and a second transistor. The switching circuit has the function of controlling the electrical connection between a first terminal and a second terminal. The mechanical relay has the function of disconnecting the electrical connection between the first terminal and the second terminal. The first transistor has the function of allowing a first current to flow between the first terminal and the second terminal. The second transistor has the function of allowing a second current to flow between the first terminal and the second terminal. The first current is greater than the second current.

[0009] One aspect of the present invention is a battery protection circuit, which includes a switching circuit for controlling the charging and discharging of a battery cell. The switching circuit includes a mechanical relay, a first transistor, and a second transistor. The switching circuit has the function of controlling the electrical connection between a first terminal and a second terminal. The mechanical relay has the function of blocking the electrical connection between the first terminal and the second terminal. The first transistor has the function of allowing a first current to flow between the first terminal and the second terminal. The semiconductor layer with a channel forming region in the first transistor is formed using silicon. The second transistor has the function of allowing a second current to flow between the first terminal and the second terminal. The semiconductor layer with a channel forming region in the second transistor is formed using oxide semiconductor. The first current is greater than the second current.

[0010] In one aspect of the battery protection circuit of the present invention, preferably, the first current and the second current are on-state currents flowing between the source and drain of the first transistor and the second transistor.

[0011] In one aspect of the battery protection circuit of the present invention, it is preferred that the first off-state current flowing between the source and drain when the first transistor is off is greater than the second off-state current flowing between the source and drain when the second transistor is off.

[0012] One aspect of the present invention is a battery protection circuit, which includes a switching circuit for controlling the charging and discharging of a battery cell. The switching circuit has the function of controlling the electrical connection between a first terminal and a second terminal. The switching circuit includes a first transistor, which includes a back gate electrode. By controlling the voltage applied to the back gate electrode, the first transistor can switch between a first current and a second current flowing between the first terminal and the second terminal when it is turned on. The first current is greater than the second current.

[0013] One aspect of the present invention is an energy storage device, which includes a battery cell and a switching circuit for controlling the charging and discharging of the battery cell. The switching circuit includes a mechanical relay, a first transistor, and a second transistor. The switching circuit has the function of controlling the electrical connection between a first terminal and a second terminal. The mechanical relay has the function of disconnecting the electrical connection between the first terminal and the second terminal. The first transistor has the function of allowing a first current to flow between the first terminal and the second terminal. The second transistor has the function of allowing a second current to flow between the first terminal and the second terminal. The first current is greater than the second current.

[0014] One aspect of the present invention is an energy storage device comprising a battery cell and a switching circuit for controlling the charging and discharging of the battery cell. The switching circuit includes a mechanical relay, a first transistor, and a second transistor. The switching circuit has the function of controlling the electrical connection between a first terminal and a second terminal. The mechanical relay has the function of disconnecting the electrical connection between the first terminal and the second terminal. The first transistor has the function of allowing a first current to flow between the first terminal and the second terminal. The semiconductor layer of the first transistor having a channel forming region is formed using silicon. The second transistor has the function of allowing a second current to flow between the first terminal and the second terminal. The semiconductor layer of the second transistor having a channel forming region is formed using oxide semiconductor. The first current is greater than the second current.

[0015] In one aspect of the energy storage device of the present invention, it is preferred that the first current and the second current are on-state currents flowing between the source and drain of the first transistor and the second transistor.

[0016] In one aspect of the energy storage device of the present invention, it is preferred that the first off-state current flowing between the source and drain when the first transistor is off is greater than the second off-state current flowing between the source and drain when the second transistor is off.

[0017] One aspect of the present invention is an energy storage device comprising a battery cell and a switching circuit for controlling the charging and discharging of the battery cell. The switching circuit has the function of controlling the electrical connection between a first terminal and a second terminal. The switching circuit includes a first transistor, which includes a back gate electrode. By controlling the voltage applied to the back gate electrode, the first transistor can switch between a first current and a second current flowing between the first terminal and the second terminal when it is turned on, wherein the first current is greater than the second current.

[0018] In one embodiment of the present invention, the energy storage device preferably includes a battery protection circuit for controlling the switching circuit and a charging control circuit for switching the charging mode of the battery cell. The first transistor has the function of controlling the amount of current flowing between the first terminal and the second terminal, and the battery protection circuit controls the amount of current according to the signal of the charging control circuit.

[0019] In one embodiment of the energy storage device of the present invention, it is preferred that the battery protection circuit has the function of controlling the amount of current in a manner that switches the charging mode from constant current charging mode to constant voltage charging mode.

[0020] In one aspect of the energy storage device of the present invention, it is preferred that the first transistor comprises an oxide semiconductor in the channel forming region.

[0021] One aspect of the present invention is an electrical appliance comprising the energy storage device and the frame described above.

[0022] Note that other aspects of the present invention are described in the following description and accompanying drawings of the embodiments. Invention Effects

[0023] One aspect of the present invention provides a novel battery protection circuit, energy storage device, and electrical appliance. Another aspect of the present invention provides a battery protection circuit, energy storage device, and electrical appliance with a novel structure that can both interrupt current and allow large current to flow. Therefore, it can prevent situations where charging exceeds a voltage that would result in overcharging, or discharging exceeds a voltage that would result in over-discharging.

[0024] Note that the effects of one aspect of the present invention are not limited to those listed above. The effects listed above do not preclude the existence of other effects. Other effects are those described below but not explained in this section. Those skilled in the art can derive and appropriately extract these effects not explained in this section from the description, drawings, etc. Note that one aspect of the present invention has at least one of the effects listed above and / or other effects. Therefore, one aspect of the present invention may sometimes not have the effects listed above. Brief description of the attached figures

[0025] Figure 1A , Figure 1B This is a block diagram and circuit diagram illustrating one aspect of the present invention. Figure 2A , Figure 2B , Figure 2C , Figure 2D This is a diagram illustrating one aspect of the present invention. Figure 3A , Figure 3B This is a circuit diagram illustrating one aspect of the present invention. Figure 4A , Figure 4B This is a circuit diagram illustrating one aspect of the present invention. Figure 5A , Figure 5B , Figure 5C , Figure 5DThis is a circuit diagram illustrating one aspect of the present invention. Figure 6A , Figure 6B These are diagrams and flowcharts illustrating one aspect of the present invention. Figure 7A , Figure 7B These are diagrams and flowcharts illustrating one aspect of the present invention. Figure 8A , Figure 8B This is a block diagram and circuit diagram illustrating one aspect of the present invention. Figure 9A , Figure 9B , Figure 9C These are diagrams and circuit diagrams illustrating one aspect of the present invention. Figure 10A , Figure 10B , Figure 10C These are diagrams and circuit diagrams illustrating one aspect of the present invention. Figure 11A , Figure 11B , Figure 11C This is a circuit diagram illustrating one aspect of the present invention. Figure 12A , Figure 12B , Figure 12C , Figure 12D This is a diagram illustrating one aspect of the present invention. Figure 13 This is a cross-sectional schematic diagram illustrating the structure of a semiconductor device. Figure 14 This is a cross-sectional schematic diagram illustrating the structure of a semiconductor device. Figure 15A , Figure 15B , Figure 15C This is a cross-sectional schematic diagram illustrating the structure of a semiconductor device. Figure 16A , Figure 16B This is a flowchart and perspective view showing the manufacturing process of electronic components. Figure 17A , Figure 17B , Figure 17C This is a diagram illustrating one aspect of the present invention. Figure 18A , Figure 18B , Figure 18C This is a diagram illustrating one aspect of the present invention. Figure 19A , Figure 19B , Figure 19C This is a diagram illustrating one aspect of the present invention. Figure 20A , Figure 20B This is a diagram illustrating one aspect of the present invention. Figure 21A , Figure 21B , Figure 21C This is a diagram illustrating one aspect of the present invention. Figure 22 This is a diagram illustrating one aspect of the present invention. Figure 23A , Figure 23B , Figure 23C , Figure 23D , Figure 23E This is a diagram illustrating one aspect of the present invention. Figure 24A , Figure 24B This is a layout diagram illustrating an embodiment of the present invention. Figure 25A , Figure 25B This is a layout diagram illustrating an embodiment of the present invention. Figure 26A , Figure 26B These are perspective views and circuit diagrams illustrating embodiments of the present invention. Figure 27 These are diagrams illustrating embodiments of the present invention. Figure 28 These are diagrams illustrating embodiments of the present invention. Figure 29 These are diagrams illustrating embodiments of the present invention. Figure 30 These are diagrams illustrating embodiments of the present invention. Figure 31 These are diagrams illustrating embodiments of the present invention. Figure 32 These are diagrams illustrating embodiments of the present invention. Figure 33 These are diagrams illustrating embodiments of the present invention. Figure 34 These are diagrams illustrating embodiments of the present invention. Figure 35 This is a graph showing the results of measuring the dependence of the channel length and channel width on the serration. Figure 36A , Figure 36B This is a graph showing the results obtained using a 1 / f noise measurement system. Figure 37 This is a graph illustrating the correlation between sawtooth pattern and 1 / f noise. Figure 38A , Figure 38B These are block diagrams and figures illustrating one aspect of the present invention. Methods of implementing the invention

[0026] The embodiments will now be described with reference to the accompanying drawings. It should be noted that those skilled in the art will readily understand that the embodiments can be implemented in many different forms, and their manner and details can be varied in various ways without departing from the spirit and scope of the invention. Therefore, the invention should not be construed as being limited to the contents described in the embodiments shown below.

[0027] Furthermore, in this specification, ordinal numbers such as "first," "second," and "third" are added to avoid confusion regarding the constituent elements. Therefore, they are not added to limit the number of constituent elements. Moreover, they are not added to limit the order of the constituent elements. For example, a constituent element marked "first" in one embodiment of this specification may be marked "second" in other embodiments or claims. Furthermore, for example, a constituent element marked "first" in one embodiment of this specification may be omitted in other embodiments or claims.

[0028] In the accompanying drawings, the same reference numerals are sometimes used to denote the same constituent element, constituent element with the same function, constituent element formed from the same material, or constituent element formed at the same time, and sometimes repeated descriptions are omitted.

[0029] (Implementation Method 1) Referring to Figures 1 to 12, a battery protection circuit and the structure of an energy storage device having the battery protection circuit according to one aspect of the present invention will be described.

[0030] Figure 1A An example block diagram of an energy storage device with a battery protection circuit is shown. The energy storage device 10 shown in Figure 1 includes a battery cell 11, a battery protection circuit 12, and a switching circuit 13.

[0031] The energy storage device 10 has a charging circuit for charging and / or a load for supplying power between terminals 14 and 15. The charging circuit is a circuit that supplies current (charging current) for charging the battery cells. The load is a circuit driven by the current (discharging current) flowing through the battery cells during discharge.

[0032] Battery cell 11 is described as a single battery cell, but it can also be composed of multiple battery cells. Note that battery cell 11 is described as a lithium-ion secondary battery cell, but it is not limited to lithium-ion secondary battery cells. As the positive electrode material for the secondary battery, materials containing element A, element X, and oxygen can be used, for example. Element A is preferably selected from one or more elements from Group I and Group II. As a Group I element, alkali metals such as lithium, sodium, and potassium can be used, for example. As a Group II element, calcium, beryllium, and magnesium can be used, for example. As element X, one or more elements selected from metallic elements, silicon, and phosphorus can be used, for example. Furthermore, element X is preferably selected from one or more elements selected from cobalt, nickel, manganese, iron, and vanadium. Typically, lithium cobalt composite oxide LiCoO3 and lithium iron phosphate LiFePO4 can be cited.

[0033] The battery protection circuit 12 has the function of generating signals DE and CE to control the switching circuit 13, which controls the charging current and discharging current. For example, signal DE (when there are multiple signals, they are called signals DE1 and DE2) is used to control the discharging signal. Similarly, signal CE (when there are multiple signals, they are called signals CE1 and CE2) is used to control the charging signal. The battery protection circuit 12 also has the function of monitoring the current flowing between terminals 14 and 15 or the voltage between the terminals (e.g., the voltage VH of terminal 14) and generating signals DE and CE based on the obtained voltage.

[0034] The switching circuit 13 is connected in series with the battery cell 11. The switching circuit 13 controls the charging current and discharging current flowing through the energy storage device 10 according to signals DE and CE. Specifically, the switching circuit 13 controls the electrical connection between terminals 16 and 17. Note that the switching circuit 13 operates in cooperation with the battery protection circuit 12 to prevent overcurrent or overvoltage in the battery cell 11. Therefore, in this specification and accompanying drawings, the battery protection circuit 12 and the switching circuit 13 are sometimes collectively referred to as the battery protection circuit. In this case, the switching circuit 13 is sometimes described as being included within the battery protection circuit 12.

[0035] Figure 1B This is a circuit that shows a specific example of the switching circuit 13. Figure 1B The switching circuit 13 shown includes mechanical relay 21, mechanical relay 22, transistor 23, and transistor 24. Mechanical relay 21, mechanical relay 22, transistor 23, and transistor 24 are each controlled to be turned on or off according to signal DE or signal CE.

[0036] Mechanical relays 21 and 22 (mechanical relays) include contacts and have the function of controlling whether to interrupt current by mechanically opening and closing the contacts through electromagnetic action. Mechanical relays 21 and 22 include a coil portion that receives electrical signals and converts them into mechanical motion, and a contact portion that converts the electrical signal into an opening and closing operation. Because the coil portion and the contact portion of mechanical relays 21 and 22 are physically separated, insulation between the two terminals can be ensured. That is, the current flowing when switching mechanical relays 21 and 22 to the off position can be eliminated. Note that because mechanical relays 21 and 22 have the function of switching the electrical connection between the two terminals, they are shown as switches in the accompanying drawings, etc.

[0037] Transistor 23 is a transistor (called a Si transistor) that uses silicon to form a semiconductor layer with a channel formation region. As materials used in Si transistors, both monocrystalline silicon and non-monocrystalline silicon (e.g., polycrystalline silicon) can be used. When monocrystalline silicon is used in a Si transistor, the current flowing between the source and drain when turned on (also called the on-state current) can be increased. Note that, in addition to silicon, semiconductors such as germanium (Ge), compound semiconductors such as GaAs, InP, SiC, ZnSe, GaN, and SiGe can also be used as materials for the semiconductor layer. Note that transistor 23 functions as a transistor designed to allow current to flow through a load, and is sometimes called a power MOSFET.

[0038] Transistor 24 is a transistor (called an OS transistor) that uses oxide semiconductor to form a semiconductor layer with a channel formation region. By reducing the carrier density of the oxide semiconductor, the current flowing between the source and drain when turned off can be extremely low (also called off-state current or leakage current). Details about OS transistors will be explained in later embodiments. Note that in Figure 1B The diagram shows transistor 24 as a circuit symbol with a back gate, but a structure without a back gate can also be used. Note that transistor 24 functions as a transistor designed to allow current to flow through a load, and is sometimes referred to as a power MOSFET.

[0039] OS transistors can be freely configured by being stacked on top of circuits using Si transistors, thus facilitating integration. Furthermore, OS transistors can be manufactured using the same fabrication equipment as Si transistors, enabling low-cost manufacturing.

[0040] Furthermore, when an OS transistor has a back gate electrode in addition to the gate, source, and drain electrodes, it can become a 4-terminal semiconductor device. A circuit network can be constructed that allows independent control of the input and output of the signal flowing between the source and drain based on the voltage applied to the gate or back gate electrode. Therefore, circuit design can be performed similarly to LSI transistors. Moreover, OS transistors exhibit superior electrical characteristics compared to Si transistors at high temperatures. Specifically, because the ratio of on-state current to off-state current is high even at temperatures above 100°C and below 200°C, preferably above 125°C and below 150°C, excellent switching operation is possible.

[0041] Next, use Figures 2A to 2D , Figure 3A and Figure 3B , Figure 4A and Figure 4B The circuit diagram shown is for Figure 1B The operation of the switch circuit 13 shown will be explained.

[0042] Figure 2A This diagram illustrates the three possible states of the energy storage device 10. Period T1 corresponds to the period during which the switching circuit 13 is switched to allow a large current to flow through the load. Period T2 corresponds to the period during which the following controls can be switched: controlling the current to flow through the load; controlling the current flowing through the switching circuit 13 to be extremely low. Period T3 corresponds to the period during which the current flowing through the terminals (terminals 16, 17) of the switching circuit 13 is controlled to be extremely low.

[0043] Figure 2B This diagram illustrates the operation during period T1. During period T1, the mechanical relay 21 is turned on. During period T1, the mechanical relay 22 and transistor 24 are turned off.

[0044] Such as Figure 2B As shown, by switching mechanical relays 21 and 22 and transistor 24, the switching circuit 13 can control the interruption of current based on the on or off state of transistor 23. That is, as... Figure 3A As shown, when transistor 23 is turned on, it can allow current I to flow. 23 The current I flowing through transistor 23, which is a Si transistor, is _ON. At this time, since mechanical relay 22 and transistor 24 are closed, the current I flowing through transistor 24 is _ON. 24 _OFF is extremely low. On the other hand, such as Figure 3B As shown, when transistor 23 is off, the current I, which is the off-state current, is... 23 The current _OFF flows through transistor 23, which is a Si transistor. At this time, since mechanical relay 22 and transistor 24 are off, the current I flowing through transistor 24 as the off-state current... 24_OFF is extremely low.

[0045] Figure 2C This diagram illustrates the operation during period T2. During period T2, the mechanical relay 22 is turned on. During period T2, the mechanical relay 21 and transistor 23 are turned off.

[0046] Such as Figure 2C As shown, by switching mechanical relays 21 and 22 and transistor 23, the switching circuit 13 can control the interruption of current based on the on or off state of transistor 24. That is, as... Figure 4A As shown, when transistor 24 is turned on, it can make the current I... 24 The current I flowing through transistor 23, which acts as the OS transistor, is at this time. Since mechanical relay 21 is closed, the current I flowing through transistor 24 is... 23 _OFF is extremely low. On the other hand, such as Figure 4B As shown, when transistor 24 is off, since transistor 24 is an OS transistor, the current I flowing through it is the off-state current. 24 _OFF is extremely low. At this time, since mechanical relay 21 is closed, the current I flowing through transistor 23 is... 23 _OFF is extremely low.

[0047] Figure 2D This diagram illustrates the operation during period T3. During period T3, the mechanical relays 21 and 22 are switched off. Therefore, the current I flowing through transistor 23... 23 _OFF and current I 24 _OFF values ​​are extremely low.

[0048] One aspect of the invention employs a structure in which current flows through a mechanical relay 21 and a transistor 23. By using a Si transistor, whose semiconductor layer comprises monocrystalline silicon, as transistor 23, the on-state current can be increased. The mechanical relay 21 ensures insulation between the two terminals, thus keeping the current flowing between the terminals extremely low regardless of the magnitude of the off-state current of transistor 23.

[0049] Furthermore, one aspect of the invention employs a structure in which current flows through a mechanical relay 22 and a transistor 24. By using an OS transistor, whose semiconductor layer comprises an oxide semiconductor, as transistor 24, the off-state current can be kept extremely low. The mechanical relay 22 ensures insulation between the two terminals, thus the current flowing between the terminals in the off state can be extremely low regardless of the magnitude of the off-state current of transistor 24. Therefore, by switching between transistors with different electrical characteristics, it is possible to both block the current flowing through the switching circuit and supply a large current to the load.

[0050] As shown in one aspect of the present invention, by employing a structure that utilizes a switching mechanical relay and transistors with different electrical characteristics, the frequency of switching the mechanical relay can be suppressed. Furthermore, it is possible to supply a large current to the load and to interrupt the current flowing between the terminals using extremely low off-state current.

[0051] Furthermore, by employing a structure according to one aspect of the present invention, the battery cell can be charged or a large current can be flowed through the load in a short time. Moreover, by employing a structure according to one aspect of the present invention, operation can be performed by switching the current supply and interruption without being affected by the off-state current, thus more reliably preventing situations where charging exceeds the voltage that would result in overcharging, or discharging exceeds the voltage that would result in over-discharging.

[0052] Furthermore, as described as one aspect of the present invention... Figure 1B The switching circuit 13 can also have other structures. For example, it could also be... Figure 5A The structure of the switch circuit shown is illustrated.

[0053] Figure 5A The switching circuit 13A shown includes transistor 31, transistor 32, and mechanical relay 33. Figure 1B Compared to the structure of the switching circuit 13, Figure 5A The structure of the switch circuit 13A shown can reduce one mechanical relay between terminals 16 and 17.

[0054] and Figures 2B to 2D same, Figures 5B to 5D This is a diagram used to illustrate the three possible states that the energy storage device 10 may become.

[0055] exist Figure 5B The text describes the operation of switching circuit 13A during period T1, which is equivalent to switching the load by allowing a large current to flow through it. Figure 5B In this circuit, a mechanical relay 33 is used to control the current flowing between the terminals of the switching circuit 13A by turning transistor 31 on or off. Note that during period T1, transistor 32 is turned off.

[0056] like Figure 5B As shown, the switching circuit 13A can control the interruption of current based on whether transistor 31 is turned on or off. That is, by turning on transistor 31, the current I can be interrupted. 31 _ON flows through transistor 31, which is a Si transistor. At this time, the current I is the same as the current flowing through transistor 31. 33 _ON flows through mechanical relay 33.

[0057] in addition, Figure 5CThis describes the operation corresponding to period T2, during which the following controls can be switched: controlling the flow of current through the load; controlling the current flowing through the switching circuit 13A to be extremely low. Figure 5C In this circuit, a transistor 31 is used to turn on the circuit, and the current flowing between the terminals of the switching circuit 13A is controlled by turning transistor 32 on or off. Note that during period T2, mechanical relay 33 is turned off and transistor 31 is turned on. At this time, the current I, which is the same magnitude as the current flowing through transistor 32... 31 _ON flows through transistor 31.

[0058] like Figure 5C As shown, the switching circuit 13A can control the interruption of current based on whether transistor 32 is turned on or off. That is, by turning on transistor 32, the current I can be interrupted. 32 The current flows through transistor 32, which acts as the OS transistor. Furthermore, by turning off transistor 32, which has an extremely low off-state current, the current flowing between terminals 16 and 17 is interrupted.

[0059] in addition, Figure 5D This corresponds to the operation during period T3, during which the current flowing through the terminals (terminals 16 and 17) of the switching circuit 13A is controlled to be extremely low. Figure 5D In this circuit, transistors 31 and 32 and mechanical relay 33 are turned off to control the current flowing between the terminals of the switching circuit 13A.

[0060] like Figure 5D As shown, the switching circuit 13A can interrupt the current (current I) by turning off the transistor 32 and the mechanical relay 33. 32 _OFF, Current I 33 _OFF). That is to say, by combining the transistor 32, which has an extremely low off-state current as an OS transistor, with the mechanical relay 33 to turn off, the current flowing between the terminals of the switching circuit 13A can be blocked.

[0061] By conducting Figures 5B to 5D That kind of work can give full play to... Figures 2B to 2D The same effect. For example... Figure 5A As shown in the structure, by employing a switching mechanical relay and transistors with different electrical characteristics, the switching frequency of the mechanical relay can be suppressed. Furthermore, it is possible to supply a large current to the load and interrupt the current flowing between the terminals using extremely low off-state current.

[0062] In addition, by adopting Figure 5AThe structure allows for rapid charging of battery cells or the flow of large current through a load. Furthermore, by employing a structure according to one aspect of the invention, operation can be performed by switching the current supply and interruption without being affected by the off-state current, thus more reliably preventing situations where charging exceeds the voltage that would result in overcharging, or discharging exceeds the voltage that would result in over-discharging.

[0063] Reference Figure 6A and Figure 6B When Figure 1A and Figure 1B The control of the switching circuit 13 when the battery cell 11 of the energy storage device 10 is overcharged will be explained.

[0064] Figure 6A This is a graph schematically showing the change in voltage VH on one side of terminal 14 during overcharging. During charging, voltage VH rises, becoming voltage V1 at time t1 and voltage V2 at time t2. Voltage V1 is the voltage at which charging is considered complete if it is exceeded. Voltage V2 is a higher voltage than voltage V1.

[0065] Figure 6B It is used to explain Figure 6A The flowchart shows the operation of the switching circuit 13 when the voltage changes.

[0066] In the initial state of charging, the battery protection circuit 12 activates the mechanical relay 21 (abbreviated as SW21 in the attached figure) of the switching circuit 13 and controls the activation of the transistor 23 (abbreviated as Tr23 in the attached figure) (step S001). This control is equivalent to Figures 2A to 2D The work during period T1 is described in the text.

[0067] The battery protection circuit 12 detects whether the voltage VH exceeds the voltage V1 due to the rise in voltage VH and determines that the battery is fully charged (step S002). When the voltage VH exceeds the voltage V1, it enters the next state.

[0068] When the battery is determined to be fully charged in step S002, the battery protection circuit 12 controls the transistor 23 to turn off (step S003). As described above, since the transistor 23 is a Si transistor, even when switched off, an off-state current still flows, so the voltage VH continues to rise.

[0069] The battery protection circuit 12 detects whether the voltage VH exceeds the voltage V2 due to the rise in voltage VH and determines that charging has ended (step S004). When the voltage VH exceeds the voltage V2, it enters the next state.

[0070] When the charging is determined to be complete in step S004, the battery protection circuit 12 performs control to turn off mechanical relay 21, turn on mechanical relay 22 (abbreviated as SW22 in the figure), and turn off transistor 24 (abbreviated as Tr24 in the figure) (step S005). This control is equivalent to Figures 2A to 2D The operation of T2 is described above. Since transistor 24 is an OS transistor, the off-state current when switching to off can be kept extremely low, thus suppressing the rise of voltage VH.

[0071] Reference Figure 7A and Figure 7B When Figure 1A and Figure 1B The control of the switching circuit 13 when the battery cell 11 of the energy storage device 10 starts charging will be explained.

[0072] Figure 7A This is a schematic diagram illustrating the change in voltage VH on terminal 14 at the start of charging. Before charging begins, voltage VH decreases due to discharge operation that allows current to flow through a load, etc. At time t3, voltage VH becomes voltage V3, indicating the start of charging. At time t4, voltage VH returns to V2, indicating the end of charging. On the other hand, if voltage VH continues to decrease due to the effect of the discharge operation, it becomes voltage V4 at time t5. Voltage V3 is lower than voltage V2. Voltage V4 is lower than voltage V3.

[0073] Figure 7B It is used to explain Figure 7A The flowchart shows the operation of the switching circuit 13 when the voltage changes.

[0074] The battery protection circuit 12 controls the mechanical relay 22 of the switching circuit 13 to turn on and the transistor 24 to turn off by discharging (step S006). This control is equivalent to Figures 2A to 2D The operation of T2 is described above. Since transistor 24 is an OS transistor, the off-state current when switching to off can be kept extremely low, thus suppressing the drop in voltage VH.

[0075] The battery protection circuit 12 detects whether the voltage VH is lower than the voltage V3 due to the drop in voltage VH and determines that charging should begin (step S007). When the voltage VH exceeds the voltage V2, it enters the next state.

[0076] When it is determined in step S007 that charging has started, the battery protection circuit 12 controls the transistor 24 to turn on (step S008). This control is equivalent to... Figures 2A to 2D The work during period T2 is described in the text.

[0077] The battery protection circuit 12 detects whether the voltage VH rises and exceeds the voltage V2 due to the activation of transistor 24 and determines that charging is complete (step S009). When the voltage VH exceeds the voltage V2, control the transistor 24 to turn off (step S010). As described above, since transistor 24 is an OS transistor, the off-state current when switching to off can be extremely low, thus suppressing the rise of voltage VH.

[0078] When transistor 24 is turned on but voltage VH does not rise and continues to decrease from voltage V3, battery protection circuit 12 determines whether voltage VH is lower than voltage V4 (step S011). When voltage VH is lower than voltage V4, battery protection circuit 12 controls the activation of mechanical relay 21, the deactivation of mechanical relay 22, and the activation of transistor 23 (step S012). This control is equivalent to... Figures 2A to 2D The operation of T1 is described above. As mentioned above, transistor 23 is a Si transistor and can make the current when switching to turn-on greater than the current flowing through the OS transistor, so that the voltage VH can rise even when the voltage drops significantly due to discharge operation.

[0079] In addition, when Figure 1A When the energy storage device 10 shown has a structure that uses a switching circuit 13 to switch between charging and discharging control, as an example, it adopts... Figure 8A , Figure 8B The structure is sufficient.

[0080] Figure 8A This is a block diagram of the energy storage device 10A. The energy storage device 10A and... Figure 1A The difference in the shown energy storage device 10 is that the energy storage device 10A includes a voltage detection circuit 18 in the battery protection circuit 12A for detecting the voltage between terminals 14 and 15, and a charge / discharge switching circuit 30 for switching the control between charging and discharging. The voltage detection circuit 18 has the function of generating signals DE and CE to control the charge / discharge switching circuit 30 based on the voltage between terminals 14 and 15.

[0081] Figure 8B It is shown Figure 8A The diagram shows an example of the structure of the charge / discharge switching circuit 30. Between terminals 16 and 17 are included switching circuits 13D and 13C, and a diode element 41. The discharge of battery cell 11 is controlled by switching circuit 13D. The charging of battery cell 11 is controlled by switching circuit 13C. Note that in... Figure 8B Although diode element 41 is shown in the circuit diagram, it can also be omitted by using a diode connection provided by a parasitic Si transistor.

[0082] Reference Figure 9Aand Figure 9B right Figure 8A and Figure 8B The control of the charge / discharge switching circuit 30, which includes switching circuits 13C and 13D, during the process of switching the battery cell 11 in the energy storage device 10A from discharging to charging (referred to as the start of charging) will be explained.

[0083] Figure 9A It is a graph schematically showing the change of voltage VH on one side of terminal 14 when charging begins. Figure 9A The following states are shown: the voltage VH drops due to discharging to the load (discharging operation), and after discharging to the load stops at time t6 (stopping operation) until it becomes over-discharged, the voltage VH rises at time t7 (charging operation).

[0084] in addition, Figure 9B It is visually indicated by dashed arrows. Figure 9A The diagram shows the current flowing through the charge / discharge switching circuit 30 during charging operation. (See diagram for example.) Figure 9B As shown, switch circuits 13C and 13D are turned on to allow current to flow.

[0085] in addition, Figure 9C It is shown that the process is being carried out. Figure 9A A diagram showing the state of the charge / discharge switching circuit 30 when it stops working. (See diagram for example.) Figure 9C As shown, in the switching circuit 13D, closing mechanical relays 21 and 22 causes the current (I) flowing through them to be reduced. 21 _OFF、I 22 The _OFF current is extremely low. By employing this structure, the degradation of battery cell 11 caused by over-discharge can be suppressed. Note that the low off-state current of transistor 24 can also be used to turn on the mechanical relay.

[0086] Additionally, refer to Figure 10A and Figure 10B right Figure 8A and Figure 8B The control of the charge / discharge switching circuit 30, which includes switching circuits 13C and 13D, in the energy storage device 10A described herein at the start of discharge of battery cell 11 will be explained.

[0087] Figure 10A It is a graph schematically showing the change of voltage VH on one side of terminal 14 during the process of switching from charging operation to discharging operation (referred to as the start of charging). Figure 10A The following states are shown: the voltage VH rises due to discharging (charging operation) to battery cell 11, and after discharging to battery cell 11 stops (stopping operation) at time t8 until it becomes overcharged, the voltage VH drops at time t9 when discharging (discharging operation) begins.

[0088] in addition, Figure 10B It is visually indicated by dashed arrows. Figure 10A The diagram shows the current flowing through the charge / discharge switching circuit 30 during discharge operation. (See diagram for example.) Figure 10B As shown, switch circuits 13C and 13D are turned on to allow current to flow.

[0089] in addition, Figure 10C It is shown that the process is being carried out. Figure 10A A diagram showing the state of the charge / discharge switching circuit 30 when it stops working. (See diagram below.) Figure 10C As shown, in the switching circuit 13C, mechanical relays 21 and 22 are turned off, making the current flowing through them extremely low. At this time, due to the leakage current I... 41 _OFF flows through diode element 41, so when the switching circuit 13C is turned off and no current flows, the voltage VH changes slightly.

[0090] Note that the circuit structure of the switch circuit 13 described above is not limited to... Figure 1B The switch circuit 13 shown or Figure 5A The circuit diagram of the switch circuit 13A shown is structural. Figures 11A to 11C A variation of the switching circuit is shown.

[0091] Figure 11A The switch circuit 13E shown is equivalent to omitting... Figure 1B The switch circuit 13 shown is structured so that the mechanical relay 22 supplies voltage VBG to the back gate of transistor 24. By employing... Figure 11A The structure of the switch circuit 13E shown can control the threshold voltage by shifting the voltage VBG in the positive or negative direction. This, in turn, changes the electrical characteristics of the transistor 24, thereby increasing or decreasing the current flowing between terminals 16 and 17.

[0092] Figure 11B The switch circuit 13F shown is equivalent to omitting... Figure 1B The mechanical relays 21 and 22 in the shown switching circuit 13, and transistors 23 and 24, are structured as OS transistors 23A and 24A with back gates. A voltage VBG1 can be supplied to the back gate of transistor 23A, and a voltage VBG2, different from VBG1, can be supplied to the back gate of transistor 24A. By employing... Figure 11B The structure of the switch circuit 13F shown allows for control of the threshold voltages of each transistor by controlling voltages VBG1 and VBG2 respectively. Therefore, the current flowing between terminals 16 and 17 can be increased or decreased without the need for mechanical relays 21 and 22.

[0093] Or, as Figure 11CLike the switch circuit 13G shown in the figure, a structure including the transistor 25 which is an OS transistor and has a back gate is adopted. By supplying a plurality of voltages VBG to the back gate of the transistor 25 as a plurality of voltages, the electrical characteristics of the transistor 25 can be switched. Accordingly, by switching the transistor characteristics, the amount of current flowing between the terminal 16 and the terminal 17 can be increased or decreased.

[0094] Figures 12A to 12C shows Figure 11C an operation example and an application example of the switch circuit 13G shown in the figure.

[0095] Figure 12A shows the following state: when the voltage VG is supplied to the gate of the transistor 25 of the switch circuit 13G shown in the figure and the voltage VBG is supplied to the back gate, the current ID flows between the terminal 16 and the terminal 17. Figure 11C the state where when the voltage VG is supplied to the gate of the transistor 25 of the switch circuit 13G shown in the figure and the voltage VBG is supplied to the back gate, the current ID flows between the terminal 16 and the terminal 17.

[0096] Figure 12B is a schematic diagram showing a graph of current-voltage characteristics of the transistor 25 shown in the figure. The transistor 25 can be used in the switch circuit 13G, and this transistor can switch states with different electrical characteristics by switching the back gate voltage with voltages VBG_A and VBG_B (<VBG_A). For example, the transistor 25 can be used in the switch circuit 13G, and this transistor 25 can switch the following states: setting the back gate voltage to the voltage VBG_A to increase the amount of current flowing between the terminal 16 and the terminal 17 when the transistor 25 is turned on; and setting the back gate voltage to the voltage VBG_B to make the amount of current flowing between the terminal 16 and the terminal 17 when the transistor 25 is turned off extremely low. Figure 12A is a schematic diagram showing a graph of current-voltage characteristics of the transistor 25 shown in the figure. The transistor 25 can be used in the switch circuit 13G, and this transistor can switch states with different electrical characteristics by switching the back gate voltage with voltages VBG_A and VBG_B (<VBG_A). For example, the transistor 25 can be used in the switch circuit 13G, and this transistor 25 can switch the following states: setting the back gate voltage to the voltage VBG_A to increase the amount of current flowing between the terminal 16 and the terminal 17 when the transistor 25 is turned on; and setting the back gate voltage to the voltage VBG_B to make the amount of current flowing between the terminal 16 and the terminal 17 when the transistor 25 is turned off extremely low.

[0097] By configuring the transistor of the switch circuit 13G using the transistor 25 which is an OS transistor, like the power storage device 10B shown in the figure, the switch circuit 13G can also be included in the battery protection circuit 12B. By configuring the battery protection circuit 12B using OS transistors, the battery protection circuit 12B can be made bendable, and as shown in the figure, the battery protection circuit 12B can be wrapped around and attached to the battery cell 11. Figure 12C like the power storage device 10B shown in the figure, the switch circuit 13G can also be included in the battery protection circuit 12B. By configuring the battery protection circuit 12B using OS transistors, the battery protection circuit 12B can be made bendable, and as shown in the figure, the battery protection circuit 12B can be wrapped around and attached to the battery cell 11. Figure 12D as shown in the figure, the battery protection circuit 12B can be wrapped around and attached to the battery cell 11.

[0098] In addition, a modification example of the structure of the power storage device 10B shown in the figure will be described using the following figures. The power storage device 10C shown in FIG. 38 differs from the power storage device 10B shown in the figure in that the battery protection circuit 12B and the switch circuit 13G are illustrated separately. In addition, the figure shows a charging control circuit 40 for switching the charging mode of the battery cell 11. Figure 38A , Figure 38B to Figure 12C a modification example of the structure of the power storage device 10B shown in the figure will be described. The power storage device 10C shown in FIG. 38 differs from the power storage device 10B shown in the figure in that the battery protection circuit 12B and the switch circuit 13G are illustrated separately. In addition, Figure 12C the power storage device 10B shown in the figure in that the battery protection circuit 12B and the switch circuit 13G are illustrated separately. In addition, Figure 38A shows a charging control circuit 40 for switching the charging mode of the battery cell 11.

[0099] The charging control circuit 40 switches the charging mode based on the voltage VH at terminal 14 and the voltage VL1 at terminal 15. The charging control circuit 40 switches between constant current (CC) charging mode and constant voltage (CV) charging mode, among others. During CC charging, a constant current flows through the battery cell 11 to charge it. If the battery cell 11 deteriorates, causing a change in its resistance, the voltage VH used to maintain the constant current will increase.

[0100] exist Figure 38A In this structure, the current flowing through the transistor 25 of the switching circuit 13G is adjusted according to the control of the battery protection circuit 12B. In other words, a structure that simulates the control of the transistor 25 is employed. By employing a structure that simulates the control of the transistor 25, the voltage VL2 of the negative terminal of the battery cell 11 can be controlled, and this control can be achieved by increasing the voltage VH side. Therefore, the CC charging mode can be switched to the CV charging mode by increasing the voltage VH through analog control.

[0101] Note that the analog control of transistor 25, which is used to switch charging modes, is achieved by adjusting the current applied to the gate of transistor 25 by adjusting the voltage from the battery protection circuit 12B based on the signal from the charging control circuit 40.

[0102] like Figure 38B As shown in the diagram, by simulating the control transistor 25 and switching the CC charging mode to the CV charging mode, the current I flowing through the battery cell 11 can be limited. Therefore, even when charging a degraded battery cell 11, safe charging can be achieved.

[0103] As described above, one aspect of the present invention can charge the battery cell or allow a large current to flow through the load in a short time. Furthermore, with one aspect of the present invention, operation can be performed by switching the current supply and interruption without being affected by the off-state current, thus more reliably preventing situations where charging exceeds the voltage that would result in overcharging, or discharging exceeds the voltage that would result in over-discharging.

[0104] This embodiment can be appropriately combined with descriptions of other embodiments.

[0105] (Implementation Method 2) An example of the structure of a semiconductor device that can be used in the battery protection circuit described in the above embodiments will be described.

[0106] Figure 13 The semiconductor device shown includes transistor 300, transistor 500, and capacitor 600. Figure 15AThis is a cross-sectional view of the channel length of transistor 500. Figure 15B This is a cross-sectional view of the channel width of transistor 500. Figure 15C This is a cross-sectional view of the channel width of transistor 300.

[0107] Transistor 500 is a transistor (OS transistor) in which metal oxide is contained in the channel formation region. Because transistor 500 has a small off-state current, by using it in OS transistors included in semiconductor devices, written data can be retained for a long period of time.

[0108] like Figure 13 As shown, the semiconductor device described in this embodiment includes transistor 300, transistor 500, and capacitor 600. Transistor 500 is disposed above transistor 300, and capacitor 600 is disposed above transistor 300 and transistor 500.

[0109] The transistor 300 is disposed on the substrate 311 and includes a conductor 316, an insulator 315, a semiconductor region 313 formed by a portion of the substrate 311, and low-resistance regions 314a and 314b used as source or drain regions. Furthermore, for example, the transistor 300 can be applied to Si transistors such as the transistor 23 in the above embodiment.

[0110] like Figure 15C As shown, in transistor 300, conductor 316 covers the top surface of semiconductor region 313 and the side surface in the channel width direction via insulator 315. Thus, by giving transistor 300 a Fin-type structure, the effective channel width is increased, thereby improving the on-state characteristics of transistor 300. Furthermore, since the influence of the gate electrode's electric field can be increased, the off-state characteristics of transistor 300 can be improved.

[0111] In addition, transistor 300 can be p-channel or n-channel.

[0112] The channel formation region or its vicinity in semiconductor region 313, low-resistance regions 314a and 314b used as source or drain regions, preferably contain semiconductors such as silicon-based semiconductors, and more preferably contain single-crystal silicon. Alternatively, materials containing Ge (germanium), SiGe (silicon-germanium), GaAs (gallium arsenide), GaAlAs (gallium aluminum arsenide), etc., can also be used. Silicon, by applying stress to the crystal lattice and changing the interplanar spacing to control the effective quality, can be used. Furthermore, transistor 300 can also be a HEMT (High Electron Mobility Transistor) using GaAs and GaAlAs, etc.

[0113] In the low resistance regions 314a and 314b, in addition to the semiconductor material applied to the semiconductor region 313, elements such as arsenic and phosphorus that impart n-type conductivity or elements such as boron that impart p-type conductivity are also included.

[0114] As the conductor 316 used as the gate electrode, conductive materials such as semiconductor materials, metal materials, alloy materials, or metal oxide materials containing elements that impart n-type conductivity, such as arsenic and phosphorus, or elements that impart p-type conductivity, such as boron, can be used.

[0115] Furthermore, since the work function is determined by the material of the conductor, the threshold voltage of the transistor can be adjusted by selecting the material of the conductor. Specifically, materials such as titanium nitride or tantalum nitride are preferably used as conductors. In order to combine conductivity and embeddability, a stack of metal materials such as tungsten or aluminum is preferably used as the conductor, especially tungsten in terms of heat resistance.

[0116] Notice, Figure 13 The structure of transistor 300 shown is merely an example and is not limited to this structure. Appropriate transistors can be used depending on the circuit structure or driving method. For example, when a semiconductor device is constructed using only OS transistors, such as... Figure 14 As shown, transistor 300 can have the same structure as transistor 500 using oxide semiconductor. Furthermore, the details of transistor 500 are described below.

[0117] Insulators 320, 322, 324 and 326 are stacked sequentially in a manner that covers transistor 300.

[0118] Insulators 320, 322, 324 and 326 may be made of materials such as silicon oxide, silicon oxynitride, silicon oxynitride, silicon nitride, aluminum oxide, aluminum oxynitride, aluminum oxynitride and aluminum nitride.

[0119] Note that in this specification, silicon oxynitride refers to a material in which the oxygen content is greater than the nitrogen content, while silicon oxynitride refers to a material in which the nitrogen content is greater than the oxygen content. Note that in this specification, aluminum oxynitride refers to a material in which the oxygen content is greater than the nitrogen content, while aluminum oxynitride refers to a material in which the nitrogen content is greater than the oxygen content.

[0120] The insulator 322 can also be used as a planarization film to reduce step planarization caused by transistors 300 and the like disposed below it. For example, in order to improve the flatness of the top surface of the insulator 322, its top surface can also be planarized by a planarization process such as chemical mechanical polishing (CMP).

[0121] In addition, as the insulator 324, it is preferable to use a barrier film that can prevent hydrogen or impurities from diffusing from the substrate 311 or the transistor 300 into the area where the transistor 500 is disposed.

[0122] As an example of a hydrogen-blocking film, silicon nitride formed by CVD can be used. Here, hydrogen sometimes diffuses into semiconductor devices with oxide semiconductors, such as transistor 500, causing a deterioration in the characteristics of the semiconductor device. Therefore, it is preferable to provide a film that suppresses hydrogen diffusion between transistor 500 and transistor 300. Specifically, a film that suppresses hydrogen diffusion refers to a film with a low amount of hydrogen detachment.

[0123] The amount of hydrogen removed can be measured, for example, using thermal desorption spectroscopy (TDS). For instance, in TDS analysis within a membrane surface temperature range of 50°C to 500°C, when the amount of hydrogen removed (converted to hydrogen atoms) is expressed per unit area of ​​insulator 324, the amount of hydrogen removed from insulator 324 is 10 × 10⁻⁶. 15 atoms / cm 2 The following is preferred: 5×10 15 atoms / cm 2 That's all.

[0124] Note that the dielectric constant of insulator 326 is preferably lower than that of insulator 324. For example, the relative dielectric constant of insulator 326 is preferably less than 4, more preferably less than 3. For example, the relative dielectric constant of insulator 326 is preferably less than 0.7 times that of insulator 324, more preferably less than 0.6 times. By using a material with a low dielectric constant for the interlayer film, parasitic capacitance generated between wirings can be reduced.

[0125] Furthermore, conductors 328 and 330, which are connected to capacitor 600 or transistor 500, are embedded in insulators 320, 322, 324, and 326. In addition, conductors 328 and 330 function as plugs or wiring. Note that sometimes the same reference numeral is used to indicate multiple conductors that function as plugs or wiring. Furthermore, in this specification, wiring and plugs connected to wiring can also be considered as components. That is, a portion of a conductor is sometimes used as wiring, and a portion of a conductor is sometimes used as a plug.

[0126] For the materials used in the plugs and wiring (conductor 328, conductor 330, etc.), single layers or stacks of conductive materials such as metals, alloys, metal nitrides, or metal oxides can be used. High-melting-point materials such as tungsten or molybdenum, which combine heat resistance and conductivity, are preferred; tungsten is particularly favored. Alternatively, low-resistance conductive materials such as aluminum or copper are preferred. Using low-resistance conductive materials reduces wiring resistance.

[0127] Alternatively, a wiring layer can be provided on the insulator 326 and the conductor 330. For example, in Figure 13 In the transistor 300, insulators 350, 352, and 354 are stacked sequentially. Furthermore, a conductor 356 is formed within insulators 350, 352, and 354. The conductor 356 functions as a connector or wiring for connection to the transistor 300. Moreover, the conductor 356 can be made of the same material as conductors 328 and 330.

[0128] Furthermore, similar to insulator 324, insulator 350 preferably uses an insulator that is hydrogen-barrier. Additionally, conductor 356 preferably includes a hydrogen-barrier conductor. In particular, the hydrogen-barrier conductor is formed within the openings of the hydrogen-barrier insulator 350. By employing this structure, the barrier layer can be used to separate transistor 300 from transistor 500, thereby suppressing hydrogen diffusion from transistor 300 into transistor 500.

[0129] Note that tantalum nitride, for example, is preferably used as a conductor that blocks hydrogen. Furthermore, by layering tantalum nitride and highly conductive tungsten, not only can the conductivity of the wiring be maintained, but hydrogen diffusion from the transistor 300 can also be suppressed. In this case, the tantalum nitride layer that blocks hydrogen is preferably in contact with the hydrogen-blocking insulator 350.

[0130] Alternatively, a wiring layer can be provided on the insulator 354 and the conductor 356. For example, in Figure 13 In the structure, insulators 360, 362, and 364 are stacked sequentially. Furthermore, a conductor 366 is formed within insulators 360, 362, and 364. The conductor 366 functions as a plug or wiring. Moreover, the conductor 366 can be made of the same material as conductors 328 and 330.

[0131] Furthermore, similar to insulator 324, insulator 360 preferably uses an insulator that is hydrogen-barrier. Additionally, conductor 366 preferably includes a hydrogen-barrier conductor. In particular, the hydrogen-barrier conductor is formed within the openings of the hydrogen-barrier insulator 360. By employing this structure, a barrier layer can be used to separate transistor 300 from transistor 500, thereby suppressing hydrogen diffusion from transistor 300 into transistor 500.

[0132] Alternatively, a wiring layer can be provided on the insulator 364 and the conductor 366. For example, in Figure 13In the structure, insulators 370, 372, and 374 are stacked sequentially. Furthermore, a conductor 376 is formed within insulators 370, 372, and 374. The conductor 376 functions as a plug or wiring. Moreover, the conductor 376 can be made of the same material as conductors 328 and 330.

[0133] Furthermore, similar to insulator 324, insulator 370 preferably uses an insulator that is hydrogen-barrier. Additionally, conductor 376 preferably comprises a hydrogen-barrier conductor. In particular, the hydrogen-barrier conductor is formed within the openings of the hydrogen-barrier insulator 370. By employing this structure, a barrier layer can be used to separate transistor 300 from transistor 500, thereby suppressing hydrogen diffusion from transistor 300 into transistor 500.

[0134] Alternatively, a wiring layer can be provided on the insulator 374 and the conductor 376. For example, in Figure 13 In the structure, insulators 380, 382, ​​and 384 are stacked sequentially. Furthermore, a conductor 386 is formed within insulators 380, 382, ​​and 384. The conductor 386 functions as a plug or wiring. Moreover, the conductor 386 can be made of the same material as conductors 328 and 330.

[0135] Furthermore, similar to insulator 324, insulator 380 preferably uses an insulator that is hydrogen-barrier. Additionally, conductor 386 preferably includes a hydrogen-barrier conductor. In particular, the hydrogen-barrier conductor is formed within the openings of the hydrogen-barrier insulator 380. By employing this structure, a barrier layer can be used to separate transistor 300 from transistor 500, thereby suppressing hydrogen diffusion from transistor 300 into transistor 500.

[0136] The wiring layer including conductor 356, wiring layer including conductor 366, wiring layer including conductor 376, and wiring layer including conductor 386 have been described above, but the semiconductor device according to this embodiment is not limited thereto. The wiring layer similar to the wiring layer including conductor 356 may be three or fewer layers, or the wiring layer similar to the wiring layer including conductor 356 may be five or more layers.

[0137] Insulators 510, 512, 514 and 516 are sequentially stacked on insulator 384. Preferably, any one of insulators 510, 512, 514 and 516 is a material that blocks oxygen or hydrogen.

[0138] For example, as insulators 510 and 514, it is preferable to use barrier films that can prevent hydrogen or impurities from diffusing from the substrate 311 or the region where the transistor 300 is disposed into the region where the transistor 500 is disposed. Therefore, insulators 510 and 514 can be made of the same material as insulator 324.

[0139] As an example of a hydrogen-blocking film, silicon nitride formed by CVD can be used. Here, hydrogen sometimes diffuses into semiconductor devices with oxide semiconductors, such as transistor 500, causing a deterioration in the characteristics of the semiconductor device. Therefore, it is preferable to provide a film that suppresses hydrogen diffusion between transistor 300 and transistor 500. Specifically, a film that suppresses hydrogen diffusion refers to a film with a low amount of hydrogen detachment.

[0140] For example, as a membrane that blocks hydrogen, insulators 510 and 514 are preferably made of metal oxides such as aluminum oxide, hafnium oxide, and tantalum oxide.

[0141] In particular, aluminum oxide has a high barrier effect against the permeation of oxygen and impurities such as hydrogen and moisture that cause changes in the electrical characteristics of transistors. Therefore, during and after the transistor manufacturing process, aluminum oxide can prevent impurities such as hydrogen and moisture from entering the transistor 500. Furthermore, aluminum oxide can suppress the release of oxygen from the oxides constituting the transistor 500. Therefore, aluminum oxide is suitable for use as a protective film for the transistor 500.

[0142] For example, the same materials as insulator 320 can be used as insulators 512 and 516. Furthermore, by using materials with lower dielectric constants for the aforementioned insulators, parasitic capacitances generated between wirings can be reduced. For example, silicon oxide films and silicon oxynitride films can be used as insulators 512 and 516.

[0143] Furthermore, conductors 518 and conductors constituting transistor 500 (e.g., conductor 503) are embedded in insulators 510, 512, 514, and 516. The conductor 518 is used as a plug or wiring for connection to capacitor 600 or transistor 300. The conductor 518 can be made of the same material as conductors 328 and 330.

[0144] In particular, the conductor 518 in the region in contact with insulators 510 and 514 is preferably a conductor that is resistant to oxygen, hydrogen, and water. By employing this structure, transistor 300 and transistor 500 can be separated by a layer that is resistant to oxygen, hydrogen, and water, thereby suppressing the diffusion of hydrogen from transistor 300 into transistor 500.

[0145] A transistor 500 is disposed above the insulator 516.

[0146] like Figure 15A , Figure 15B As shown, transistor 500 includes a conductor 503 disposed in a manner that embeds in insulators 514 and 516, an insulator 520 disposed on insulators 516 and conductor 503, an insulator 522 disposed on insulator 520, an insulator 524 disposed on insulator 522, an oxide 530a disposed on insulator 524, an oxide 530b disposed on oxide 530a, conductors 542a and 542b disposed separately on oxide 530b, an insulator 580 disposed on conductors 542a and 542b and forming an opening that overlaps between conductors 542a and 542b, an oxide 530c disposed on the bottom and side surfaces of the opening, an insulator 550 disposed on the forming surface of oxide 530c, and a conductor 560 disposed on the forming surface of insulator 550.

[0147] In addition, such as Figure 15A , Figure 15B As shown, preferably, an insulator 544 is disposed between oxide 530a, oxide 530b, conductor 542a and conductor 542b and insulator 580. Furthermore, as... Figure 15A , Figure 15B As shown, the conductor 560 preferably includes a conductor 560a disposed inside the insulator 550 and a conductor 560b disposed in such a manner that it is embedded inside the conductor 560a. Furthermore, as... Figure 15A , Figure 15B As shown, an insulator 574 is preferably disposed on the insulator 580, the conductor 560 and the insulator 550.

[0148] Note that oxides 530a, 530b, and 530c are sometimes collectively referred to as oxide 530.

[0149] In transistor 500, three layers of oxide 530a, oxide 530b, and oxide 530c are stacked in and around the region forming the channel; however, the present invention is not limited to this. For example, a single layer of oxide 530b, a two-layer structure of oxide 530b and oxide 530a, a two-layer structure of oxide 530b and oxide 530c, or a stacked structure of four or more layers can be provided. Furthermore, in transistor 500, conductor 560 has a two-layer structure; however, the present invention is not limited to this. For example, conductor 560 can also have a single-layer structure or a stacked structure of three or more layers. Note that... Figure 13 , Figure 15A The structure of transistor 500 shown is only an example and is not limited to the structure described above. Appropriate transistors can be used depending on the circuit structure or driving method.

[0150] Here, conductor 560 is used as the gate electrode of the transistor, and conductors 542a and 542b are used as source or drain electrodes. As described above, conductor 560 is disposed in a manner that embeds it in the opening of insulator 580 and sandwiched in the region between conductors 542a and 542b. The configuration of conductors 560, 542a, and 542b relative to the opening of insulator 580 is self-aligned. In other words, in transistor 500, the gate electrode can be self-aligned between the source and drain electrodes. Therefore, conductor 560 can be formed without providing room for alignment, thus reducing the occupied area of ​​transistor 500. This enables miniaturization and high integration of semiconductor devices.

[0151] Furthermore, conductor 560 is self-aligned and formed in the region between conductors 542a and 542b, so conductor 560 does not include the region overlapping with conductors 542a and 542b. This reduces the parasitic capacitance formed between conductor 560 and conductors 542a and 542b. Therefore, the switching speed of transistor 500 can be increased, allowing transistor 500 to have high-frequency characteristics.

[0152] Conductor 560 is sometimes used as the first gate (also called the top gate) electrode. Conductor 503 is sometimes used as the second gate (also called the bottom gate) electrode. In this case, the threshold voltage of transistor 500 can be controlled by independently changing the potential supplied to conductor 503 without linking it to the potential supplied to conductor 560. In particular, by supplying a negative potential to conductor 503, the threshold voltage of transistor 500 can be made greater than 0V and the off-state current can be reduced. Therefore, compared with not applying a negative potential to conductor 503, applying a negative potential to conductor 503 can reduce the drain current when the potential applied to conductor 560 is 0V.

[0153] Conductor 503 is arranged to overlap with oxide 530 and conductor 560. Therefore, when a potential is supplied to conductor 560 and conductor 503, the electric field generated from conductor 560 and the electric field generated from conductor 503 are connected, and can cover the channel formation region formed in oxide 530. In this specification, the structure of a transistor in which the electric field of the first gate electrode and the electric field of the second gate electrode surround the channel formation region is referred to as a surround channel (S-channel) structure.

[0154] Furthermore, conductor 503 has the same structure as conductor 518, with conductor 503a formed in contact with the inner walls of the openings of insulator 514 and insulator 516, and conductor 503b formed on its inner side. Additionally, in transistor 500, conductors 503a and 503b are stacked, but the present invention is not limited thereto. For example, conductor 503 may have a single-layer structure or a stacked structure of three or more layers.

[0155] Here, the conductive material 503a is preferably a conductive material that has the function of suppressing the diffusion of impurities such as hydrogen atoms, hydrogen molecules, water molecules, and copper atoms (making it difficult for the aforementioned impurities to permeate). Additionally, it is preferable to use a conductive material that has the function of suppressing the diffusion of oxygen (e.g., at least one of oxygen atoms and oxygen molecules) (making it difficult for the aforementioned oxygen to permeate). 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 aforementioned impurities and oxygen.

[0156] For example, by giving conductor 503a the function of inhibiting oxygen diffusion, the decrease in conductivity caused by the oxidation of conductor 503b can be suppressed.

[0157] Furthermore, when conductor 503 also functions as wiring, it is preferable to use a highly conductive material with tungsten, copper, or aluminum as the main components of conductor 503b. Note that in the accompanying drawings, conductor 503b has a single-layer structure, but it can also have a multilayer structure, for example, a multilayer structure of titanium or titanium nitride and the aforementioned conductive material.

[0158] Insulators 520, 522 and 524 are used as the second gate insulating film.

[0159] Here, the insulator 524 in contact with the oxide 530 is preferably an insulator containing oxygen in excess of its stoichiometric composition. In other words, it is preferable to form an excess oxygen region in the insulator 524. By providing the aforementioned insulator containing excess oxygen in a manner that allows it to contact the oxide 530, oxygen vacancies in the oxide 530 can be reduced, thereby improving the reliability of the transistor 500.

[0160] Specifically, as an insulator with an excess oxygen region, an oxide material in which a portion of the oxygen is removed by heating is preferred. An oxide in which oxygen is removed by heating is defined as one in which the amount of oxygen removed, converted to oxygen atoms, in TDS (Thermal Desorption Spectroscopy) analysis is 1.0 × 10⁻⁶. 18 atoms / cm 3 The preferred value is 1.0 × 10⁴. 19 atoms / cm 3The above is further preferred to be 2.0×10 19 atoms / cm 3 The above, or 3.0×10 20 atoms / cm 3 The above-mentioned oxide film. Furthermore, the surface temperature of the film during the above TDS analysis is preferably in the range of 100°C or higher and 700°C or lower, or 100°C or higher and 400°C or lower.

[0161] When the insulator 524 has an excess oxygen region, the insulator 522 preferably has the function of inhibiting the diffusion of oxygen (e.g., oxygen atoms, oxygen molecules, etc.) (making it difficult for the aforementioned oxygen to pass through).

[0162] When the insulator 522 has the function of suppressing the diffusion of oxygen or impurities, the oxygen contained in the oxide 530 does not diffuse to the side of the insulator 520, which is preferred. In addition, the reaction between the conductor 503 and the oxygen contained in the insulator 524 or the oxide 530 can be suppressed.

[0163] As the insulator 522, a single layer or stack of insulators comprising so-called high-k materials such as aluminum oxide, hafnium oxide, oxides containing aluminum and hafnium (hafnium aluminate), tantalum oxide, zirconium oxide, lead zirconate titanate (PZT), strontium titanate (SrTiO3), or (Ba,Sr)TiO3 (BST) is preferably used. When miniaturizing and highly integrating transistors, problems such as leakage current sometimes occur due to the thinning of the gate insulating film. By using a high-k material as the insulator used as the gate insulating film, the gate potential during transistor operation can be reduced while maintaining the physical thickness.

[0164] In particular, it is preferable to use an insulator containing an oxide of one or both of aluminum and hafnium, which serves as an insulating material that inhibits the diffusion of impurities and oxygen (making it difficult for the aforementioned oxygen to permeate). As an insulator containing an oxide of one or both of aluminum and hafnium, aluminum oxide, hafnium oxide, or an oxide containing aluminum and hafnium (hafnium aluminate) are preferred. When this material is used to form the insulator 522, the insulator 522 serves as a layer that inhibits the release of oxygen from the oxide 530 or the entry of impurities such as hydrogen from the periphery of the transistor 500 into the oxide 530.

[0165] Alternatively, aluminum oxide, bismuth oxide, germanium oxide, niobium oxide, silicon oxide, titanium oxide, tungsten oxide, yttrium oxide, or zirconium oxide can be added to the insulator. Furthermore, the insulator can be nitrided. Additionally, silicon oxide, silicon oxynitride, or silicon nitride can be laminated onto the insulator.

[0166] The insulator 520 preferably has thermal stability. For example, silicon oxide and silicon oxynitride are preferred because they have thermal stability. In addition, by combining a high-k material insulator with silicon oxide or silicon oxynitride, an insulator 520 with a multilayer structure that has thermal stability and a high relative permittivity can be formed.

[0167] In addition, Figure 15A and Figure 15B In the transistor 500, insulators 520, 522, and 524 are shown as the second gate insulating film, which is a three-layer stacked structure. However, the second gate insulating film may also have a single-layer structure, a two-layer structure, or a stacked structure with four or more layers. In this case, it is not limited to using a stacked structure made of the same material, and a stacked structure made of different materials may also be used.

[0168] In transistor 500, a metal oxide, preferably used as an oxide semiconductor, is used for oxide 530, which includes the channel formation region. For example, as oxide 530, In-M-Zn oxide (where element M is selected from one or more of aluminum, gallium, yttrium, copper, vanadium, beryllium, boron, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, and magnesium) is preferred. In particular, CAAC (c-axis-aligned crystalline)-OS (oxide semiconductor) or CAC (cloud-aligned composite)-OS is preferred as the In-M-Zn oxide that can be used as oxide 530. Furthermore, In-Ga oxide and In-Zn oxide can also be used as oxide 530. Note that when it is desired to increase the on-state current of transistor 500, In-Zn oxide is preferred as oxide 530. When In-Zn oxide is used as oxide 530, for example, the following structures can be described: a stacked structure in which oxide 530a uses In-Zn oxide and oxides 530b and oxide 530c use In-M-Zn oxide; or a stacked structure in which oxide 530a uses In-M-Zn oxide and either oxide 530b or oxide 530c uses In-Zn oxide, etc.

[0169] As the metal oxide used in the oxide 530 for the channel formation region, it is preferable to use a metal oxide with a band gap of 2 eV or more, and more preferably 2.5 eV or more. In this way, by using a metal oxide with a wider band gap, the off-state current of the transistor can be reduced.

[0170] In oxide 530, when oxide 530a is disposed below oxide 530b, the diffusion of impurities from the structure formed below oxide 530a to oxide 530b can be suppressed. When oxide 530c is disposed above oxide 530b, the diffusion of impurities from the structure formed above oxide 530c to oxide 530b can be suppressed.

[0171] Furthermore, oxide 530 preferably has a stacked structure of multiple oxide layers having different atomic ratios for each metal atom. Specifically, the atomic ratio of element M in the constituent elements of the metal oxide used for oxide 530a is preferably greater than that in the constituent elements of the metal oxide used for oxide 530b. Additionally, the atomic ratio of element M relative to In in the metal oxide used for oxide 530a is preferably greater than that in the metal oxide used for oxide 530b. Furthermore, the atomic ratio of In relative to element M in the metal oxide used for oxide 530b is preferably greater than that in the metal oxide used for oxide 530a. Additionally, oxide 530c can use a metal oxide that can be used for oxide 530a or oxide 530b.

[0172] Preferably, the conduction band bottom energies of oxides 530a and 530c are higher than those of oxide 530b. In other words, the electron affinity of oxides 530a and 530c is preferably less than that of oxide 530b.

[0173] Here, at the junction of oxides 530a, 530b, and 530c, the energy level at the conduction band bottom changes gradually. In other words, the above situation can also be expressed as the energy level at the conduction band bottom of the junction of oxides 530a, 530b, and 530c changing continuously or continuously joining. For this purpose, it is preferable to reduce the defect state density of the mixed layer formed at the interface between oxides 530a and 530b, and at the interface between oxides 530b and 530c.

[0174] Specifically, by including oxides 530a and 530b, and oxides 530b and 530c, in addition to oxygen, a common element (as the main component) can be formed, resulting in a mixed layer with low defect state density. For example, when oxide 530b is an In-Ga-Zn oxide, In-Ga-Zn oxide, Ga-Zn oxide, and gallium oxide are preferably used as oxides 530a and 530c.

[0175] At this point, the primary pathway for charge carriers is oxide 530b. By equipping oxides 530a and 530c with the aforementioned structure, the defect state density at the interfaces between oxides 530a and 530b, and between oxides 530b and 530c, can be reduced. Therefore, the influence of interface scattering on charge carrier conduction is reduced, thereby increasing the on-state current of transistor 500.

[0176] Conductors 542a and 542b, serving as source and drain electrodes, are disposed on oxide 530b. Preferably, conductors 542a and 542b are 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, alloys containing the aforementioned metals, or alloys combining the aforementioned metals. For example, tantalum nitride, titanium nitride, tungsten, 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. Furthermore, tantalum nitride, titanium nitride, nitrides containing titanium and aluminum, nitrides containing tantalum and aluminum, ruthenium oxide, ruthenium nitride, oxides containing strontium and ruthenium, and oxides containing lanthanum and nickel are preferred materials as they are conductive materials that are not easily oxidized or maintain conductivity even when absorbing oxygen. Metal nitride films such as tantalum nitride are even more preferred because they provide a barrier against hydrogen or oxygen.

[0177] Furthermore, although Figure 15 shows a single-layer structure for conductors 542a and 542b, a stacked structure of two or more layers can also be used. For example, a tantalum nitride film and a tungsten film are preferably stacked. Alternatively, a titanium film and an aluminum film can also be stacked. Additionally, a two-layer structure with an aluminum film stacked on a tungsten film, a two-layer structure with a copper film stacked on a copper-magnesium-aluminum alloy film, a two-layer structure with a copper film stacked on a titanium film, or a two-layer structure with a copper film stacked on a tungsten film can also be used.

[0178] Alternatively, a three-layer structure can be used, in which an aluminum or copper film is laminated on a titanium or titanium nitride film and a titanium or titanium nitride film is formed thereon; or a three-layer structure can be used, in which an aluminum or copper film is laminated on a molybdenum or molybdenum nitride film and a molybdenum or molybdenum nitride film is formed thereon. Additionally, transparent conductive materials containing indium oxide, tin oxide, or zinc oxide can also be used.

[0179] In addition, such as Figure 15A As shown, regions 543a and 543b are sometimes formed as low-resistance regions at and near the interface between oxide 530 and conductor 542a (conductor 542b). In this case, region 543a is used as one of the source and drain regions, and region 543b is used as the other of the source and drain regions. Furthermore, a channel forming region is formed in the region sandwiched between region 543a and region 543b.

[0180] By providing the conductor 542a (conductor 542b) in contact with the oxide 530, the oxygen concentration in region 543a (region 543b) sometimes decreases. Furthermore, a metal compound layer comprising the metal contained in the conductor 542a (conductor 542b) and the oxide 530 sometimes forms in region 543a (region 543b). In this case, the carrier concentration in region 543a (region 543b) increases, and region 543a (region 543b) becomes a low-resistance region.

[0181] The insulator 544 is provided to cover the conductors 542a and 542b to suppress the oxidation of the conductors 542a and 542b. Alternatively, the insulator 544 can be provided to cover the side surface of the oxide 530 and be in contact with the insulator 524.

[0182] As the insulator 544, one or more metal oxides selected from hafnium, aluminum, gallium, yttrium, zirconium, tungsten, titanium, tantalum, nickel, germanium, neodymium, lanthanum, or magnesium can be used. Alternatively, silicon oxynitride or silicon nitride can also be used as the insulator 544.

[0183] In particular, as the insulator 544, it is preferable to use alumina, hafnium oxide, or an oxide containing aluminum and hafnium (hafnium aluminate), which are oxides containing one or both of aluminum and hafnium. Hafnium aluminate, in particular, has higher heat resistance than hafnium oxide film. Therefore, it is less prone to crystallization during subsequent heat treatment processes, making it preferred. Furthermore, if the conductors 542a and 542b are oxidation-resistant materials or their conductivity does not significantly decrease upon oxygen absorption, it is not necessary to provide the insulator 544. It can be appropriately designed according to the desired transistor characteristics.

[0184] By including insulator 544, impurities such as water and hydrogen contained in insulator 580 can be suppressed from diffusing through oxide 530c and insulator 550 to oxide 530b. Furthermore, excess oxygen contained in insulator 580 can be suppressed from oxidizing conductor 560.

[0185] Insulator 550 is used as the first gate insulating film. Insulator 550 is preferably arranged in such a way that it contacts the inside (top and side surfaces) of oxide 530c. Insulator 550 is preferably formed using an insulator containing excess oxygen and releasing oxygen by heating, similar to insulator 524 described above.

[0186] Specifically, silicon oxide containing excess oxygen, silicon oxynitride, silicon oxynitride, silicon nitride, silicon oxide with added fluorine, silicon oxide with added carbon, silicon oxide with added carbon and nitrogen, and porous silicon oxide can be used. In particular, silicon oxide and silicon oxynitride are preferred because they have thermal stability.

[0187] By providing an insulator 550 that releases oxygen upon heating in contact with the top surface of oxide 530c, oxygen can be efficiently supplied from the insulator 550 to the channel formation region of oxide 530b through oxide 530c. Furthermore, similar to insulator 524, it is preferable to reduce the concentration of impurities such as water or hydrogen in insulator 550. The thickness of insulator 550 is preferably 1 nm or more and 20 nm or less.

[0188] Furthermore, in order to efficiently supply the excess oxygen contained in the insulator 550 to the oxide 530, a metal oxide may be disposed between the insulator 550 and the conductor 560. This metal oxide preferably suppresses oxygen diffusion from the insulator 550 to the conductor 560. By disposing of a metal oxide that suppresses oxygen diffusion, the diffusion of excess oxygen from the insulator 550 to the conductor 560 is suppressed. In other words, the reduction in the amount of excess oxygen supplied to the oxide 530 can be suppressed. Additionally, oxidation of the conductor 560 due to excess oxygen can be suppressed. As this metal oxide, a material suitable for the insulator 544 can be used.

[0189] Furthermore, similar to the second gate insulating film, the insulator 550 can also have a stacked structure. Since thin-film gate insulating films sometimes lead to problems such as leakage current during transistor miniaturization and high integration, by using a stacked structure of a high-k material and a thermally stable material in the insulator used as the gate insulating film, the gate potential during transistor operation can be reduced while maintaining the physical thickness. Moreover, a stacked structure with thermal stability and a high relative permittivity can be achieved.

[0190] exist Figure 15A and Figure 15B In this process, the conductor 560 used as the first gate electrode has a two-layer structure, but it can also have a single-layer structure or a stacked structure of three or more layers.

[0191] As the conductor 560a, a conductive material with the function of suppressing the diffusion of impurities such as hydrogen atoms, hydrogen molecules, water molecules, nitrogen atoms, nitrogen molecules, nitrogen oxide molecules (N2O, NO, NO2, etc.), and copper atoms is preferably used. Furthermore, a conductive material with the function of suppressing the diffusion of oxygen (e.g., at least one of oxygen atoms, oxygen molecules, etc.) is preferably used. By giving the conductor 560a the function of suppressing oxygen diffusion, the decrease in conductivity caused by the oxidation of the conductor 560b due to oxygen contained in the insulator 550 can be suppressed. For example, tantalum, tantalum nitride, ruthenium, or ruthenium oxide are preferably used as the conductive material with the function of suppressing oxygen diffusion. In addition, an oxide semiconductor applicable to the oxide 530 can be used as the conductor 560a. In this case, by forming the conductor 560b using a sputtering method, the resistance value of the oxide semiconductor can be reduced to a value sufficient to make it a conductor, thus the conductor 560a can have good conductivity. This can be referred to as an OC (Oxide Conductor) electrode.

[0192] As the conductor 560b, a conductive material with tungsten, copper, or aluminum as its main components is preferably used. Since the conductor 560b is also used for wiring, a conductor with high conductivity is preferred. The conductor 560b may also have a multilayer structure, for example, a multilayer structure of titanium or titanium nitride and the aforementioned conductive material may be used.

[0193] Insulator 580 is preferably disposed on conductors 542a and 542b, separated by insulator 544. Insulator 580 preferably has excess oxygen regions. For example, insulator 580 preferably comprises silicon oxide, silicon oxynitride, silicon oxynitride, silicon nitride, fluorine-added silicon oxide, carbon-added silicon oxide, carbon and nitrogen-added silicon oxide, porous silicon oxide, or resin, etc. In particular, silicon oxide and silicon oxynitride are preferred due to their thermal stability. In particular, silicon oxide and porous silicon oxide are preferred because they readily form excess oxygen regions in subsequent processes.

[0194] By placing an insulator 580 that releases oxygen upon heating in contact with oxide 530c, oxygen in the insulator 580 can be efficiently supplied to oxide 530c. Furthermore, it is preferable to reduce the concentration of impurities such as water or hydrogen in the insulator 580.

[0195] The opening of the insulator 580 is formed to overlap with the area between the conductors 542a and 542b. Thus, the conductor 560 is disposed such that it is embedded in the opening of the insulator 580 and sandwiched in the area between the conductors 542a and 542b.

[0196] When miniaturizing semiconductor devices, it is necessary to shorten the gate length, but it is also necessary to prevent a decrease in the conductivity of the conductor 560. Therefore, by increasing the thickness of the conductor 560, it is possible for the conductor 560 to have a high aspect ratio. In this embodiment, since the conductor 560 is disposed in an opening embedded in the insulator 580, even if the conductor 560 has a high aspect ratio, it will not collapse during the manufacturing process.

[0197] The insulator 574 is preferably disposed on 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 using a sputtering method, excess oxygen regions can be formed in the insulator 550 and the insulator 580. Oxygen can then be supplied from these excess oxygen regions to the oxide 530.

[0198] For example, as insulator 574, one or more metal oxides selected from hafnium, aluminum, gallium, yttrium, zirconium, tungsten, titanium, tantalum, nickel, germanium and magnesium may be used.

[0199] In particular, alumina has high barrier properties, and even thin films with a diameter of 0.5 nm to 3.0 nm can suppress the diffusion of hydrogen and nitrogen. Therefore, alumina formed by sputtering can function as both an oxygen supply source and a barrier film against impurities such as hydrogen.

[0200] Furthermore, it is preferable to provide an insulator 581, which serves as an interlayer film, on the insulator 574. Similar to the insulator 524, it is preferable to reduce the concentration of impurities such as water or hydrogen in the insulator 581.

[0201] Furthermore, conductors 540a and 540b are disposed in openings formed in insulators 581, 574, 580, and 544. Conductors 540a and 540b are disposed opposite to each other with a gap between them and conductor 560. Conductors 540a and 540b have the same structure as conductors 546 and 548, which will be described later.

[0202] An insulator 582 is provided on insulator 581. Insulator 582 is preferably made of a material that blocks oxygen or hydrogen. Therefore, the same material as insulator 514 can be used as insulator 582. For example, metal oxides such as alumina, hafnium oxide, and tantalum oxide are preferably used as insulator 582.

[0203] In particular, aluminum oxide has a high barrier effect against the permeation of oxygen and impurities such as hydrogen and moisture that cause changes in the electrical characteristics of transistors. Therefore, during and after the transistor manufacturing process, aluminum oxide can prevent impurities such as hydrogen and moisture from entering the transistor 500. Furthermore, aluminum oxide can suppress the release of oxygen from the oxides constituting the transistor 500. Therefore, aluminum oxide is suitable for use as a protective film for the transistor 500.

[0204] Furthermore, an insulator 586 is provided on insulator 582. The same material as insulator 320 can be used as insulator 586. Moreover, by using a material with a low dielectric constant as insulator 586, parasitic capacitance generated between wirings can be reduced. For example, silicon oxide film and silicon oxynitride film can be used as insulator 586.

[0205] In addition, conductors 546 and 548 are embedded in insulators 520, 522, 524, 544, 580, 574, 581, 582 and 586.

[0206] Conductors 546 and 548 are used as plugs or wiring for connection to capacitor 600, transistor 500, or transistor 300. Conductors 546 and 548 may be made of the same material as conductors 328 and 330.

[0207] Next, a capacitor 600 is disposed above the transistor 500. The capacitor 600 includes a conductor 610, a conductor 620, and an insulator 630.

[0208] Alternatively, conductor 612 may be provided on conductors 546 and 548. Conductor 612 is used as a plug or wiring for connection to transistor 500. Conductor 610 is used as an electrode of capacitor 600. Furthermore, conductors 612 and 610 may be formed simultaneously.

[0209] Conductors 612 and 610 can be metal films containing elements selected from molybdenum, titanium, tantalum, tungsten, aluminum, copper, chromium, neodymium, and scandium, or metal nitride films (tantalum nitride film, titanium nitride film, molybdenum nitride film, tungsten nitride film) containing the aforementioned elements. Alternatively, conductive materials 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, and indium tin oxide with added silicon oxide can also be used.

[0210] exist Figure 13In this embodiment, conductors 612 and 610 have a single-layer structure, but are not limited to this; they may also have a stacked structure of two or more layers. For example, a conductor with high density to both the barrier conductor and the highly conductive conductor may be formed between the barrier conductor and the highly conductive conductor.

[0211] The conductor 620 is disposed such that it overlaps the conductor 610 with an insulator 630 in between. Conductive materials such as metals, alloys, and metal oxides can be used as the conductor 620. High-melting-point materials such as tungsten or molybdenum, which combine heat resistance and conductivity, are preferred, with tungsten being particularly preferred. When the conductor 620 is formed simultaneously with other components such as conductors, low-resistance metal materials such as Cu (copper) or Al (aluminum) can be used.

[0212] An insulator 640 is provided on the conductor 620 and the insulator 630. The insulator 640 can be made of the same material as the insulator 320. In addition, the insulator 640 can be used as a planarization film covering the uneven shape underneath.

[0213] By adopting this structure, reliability can be improved while suppressing electrical characteristic variations in semiconductor devices using transistors containing oxide semiconductors. Furthermore, miniaturization or high integration can be achieved in battery protection circuits using transistors containing oxide semiconductors.

[0214] This embodiment can be appropriately combined with descriptions of other embodiments.

[0215] (Implementation Method 3) In this embodiment, an example of the battery protection circuit used as an electronic component in the above-described embodiment will be described with reference to FIG16.

[0216] exist Figure 16A This section describes an example of the battery protection circuit described in the above embodiments being used as an electronic component. Note that electronic components are also referred to as semiconductor packages or IC packages. These electronic components have different specifications and names depending on the terminal removal direction or the shape of the terminals. In this embodiment, an example is described.

[0217] By combining multiple components that can be mounted and dismounted on a printed circuit board in the assembly process (post-process), a circuit section composed of OS transistors or Si transistors is completed.

[0218] The subsequent process can be carried out Figure 16A The process shown is completed. Specifically, after the component substrate obtained from the previous process is completed (step S1), the back side of the substrate is ground (step S2). By thinning the substrate at this stage, warpage and other defects of the substrate generated in the previous process can be reduced, thereby achieving miniaturization of the component.

[0219] The back side of the substrate is ground, and a dicing process is performed to divide the substrate into multiple chips. Then, a die bonding process (step S3) is performed to mount the diced chips onto a lead frame and achieve bonding. The bonding method between the chips and the lead frame in this die bonding process can be appropriately selected according to the product, such as using resin bonding or adhesive tape bonding. Alternatively, in the die bonding process, the chips can also be mounted onto an interposer to achieve bonding.

[0220] Next, wire bonding (step S4) is performed to electrically connect the leads of the lead frame to the electrodes on the chip using metal wires. Silver or gold wires can be used as the metal wires. Furthermore, ball bonding or wedge bonding can be used for wire bonding.

[0221] After wire bonding, the chip undergoes a molding process (step S5) that seals it with epoxy resin or similar materials. By performing the molding process, the interior of the electronic component is filled with resin, which reduces damage to the circuitry and metal wires installed inside the electronic component caused by mechanical forces, and also reduces performance degradation caused by moisture or dust.

[0222] Next, the leads of the lead frame are electroplated. The leads are then cut and shaped (step S6). This electroplating process prevents the leads from rusting and allows for more reliable soldering when the leads are subsequently mounted on the printed circuit board.

[0223] Next, marking is applied to the package surface (step S7). Then, the electronic component, including the circuitry containing the PLD, is completed through a final inspection process (step S8) (step S9).

[0224] Figure 16B A perspective view of the completed electronic components is shown. Figure 16B The image shows a perspective view of a QFP (Quad Flat Package) as an example of an electronic component. Figure 16B The electronic component 700 shown includes leads 701 and a circuit section 703. Figure 16B The electronic component 700 shown is mounted on a printed circuit board 702, for example. By combining multiple such electronic components 700 and electrically connecting them to each other on the printed circuit board 702, they can be installed inside an electronic device. The completed circuit board 704 is disposed inside an electronic device or the like.

[0225] (Implementation Method 4) In this embodiment, the structure of an energy storage device and energy storage system that can use electronic components including the battery protection circuit described in the above embodiments will be described.

[0226] Cylindrical secondary battery Reference Figure 17A Provide an example of a cylindrical secondary battery. For example... Figure 17A As shown, the top surface of the cylindrical secondary battery 400 includes a positive electrode cover (battery cover) 401, and its sides and bottom surface include a battery can (outer packaging can) 402. These positive electrode covers 401 and the battery can (outer packaging can) 402 are insulated from each other by gaskets (insulating gaskets) 410.

[0227] Figure 17B An example of an energy storage system 415 is shown. The energy storage system 415 includes a plurality of secondary batteries 400. The positive terminal of each secondary battery is in contact with a conductor 424 separated by an insulator 425, and these positive terminals are electrically connected to each other. The conductor 424 is electrically connected to a control circuit 420 via wiring 423. Furthermore, the negative terminal of each secondary battery is electrically connected to the control circuit 420 via wiring 426. The control circuit 420 may use a battery protection circuit as described in the above embodiment.

[0228] Figure 17C An example of an energy storage system 415 is shown. The energy storage system 415 includes multiple secondary batteries 400 sandwiched between conductive plates 413 and 414. The multiple secondary batteries 400 are electrically connected to the conductive plates 413 and 414 via wiring 416. The multiple secondary batteries 400 can be connected in parallel, in series, or in parallel followed by series connection. By configuring the energy storage system 415 including multiple secondary batteries 400, a large amount of power can be obtained.

[0229] Alternatively, a temperature control device can be included among the multiple secondary batteries 400. The secondary battery 400 can be cooled by the temperature control device when it overheats, and heated by the temperature control device when it becomes too cold. Therefore, the performance of the energy storage system 415 is less susceptible to the influence of external temperature.

[0230] In addition, Figure 17C In this embodiment, the energy storage system 415 is electrically connected to the control circuit 420 via wiring 421 and wiring 422. The control circuit 420 can be a battery protection circuit as described above. Wiring 421 is electrically connected to the positive terminal of the plurality of secondary batteries 400 via conductive plate 413, and wiring 422 is electrically connected to the negative terminal of the plurality of secondary batteries 400 via conductive plate 414.

[0231] [Secondary battery pack] Next, an example of an energy storage system according to one aspect of the present invention will be described with reference to FIG18.

[0232] Figure 18A This is a diagram showing the appearance of the secondary battery pack 531. Figure 18B This diagram illustrates the structure of the secondary battery pack 531. The secondary battery pack 531 includes a circuit board 501 and a secondary battery 513. A label 509 is attached to the secondary battery 513. The circuit board 501 is secured by a sealing tape 515. Furthermore, the secondary battery pack 531 includes an antenna 517.

[0233] Circuit board 501 includes control circuit 590. As control circuit 590, a battery protection circuit as described in the above embodiment can be used. For example, such as... Figure 18B As shown, the circuit board 501 includes a control circuit 590. Additionally, the circuit board 501 is electrically connected to terminal 511. Furthermore, the circuit board 501 is electrically connected to antenna 517, one of the positive and negative leads of the secondary battery 513 (551), and the other of the positive and negative leads (552).

[0234] Or, such as Figure 18C As shown, it may also include a circuit system 590a disposed on the circuit board 501 and a circuit system 590b electrically connected to the circuit board 501 via a terminal 511. For example, a portion of the control circuit of one embodiment of the present invention is disposed in the circuit system 590a, while another portion of the control circuit of one embodiment of the present invention is disposed in the circuit system 590b.

[0235] Furthermore, the shape of antenna 517 is not limited to a coil shape; for example, it can be a wire or a plate. Additionally, planar antennas, aperture antennas, traveling wave antennas, EH antennas, magnetic field antennas, or dielectric antennas can also be used. Alternatively, antenna 517 can also be a planar conductor. This planar conductor can also be used as one of the conductors for electric field coupling. In other words, antenna 517 can also be used as one of the two conductors in a capacitor. Thus, not only electromagnetic and magnetic fields can be utilized, but also electric fields can be used to exchange power.

[0236] The secondary battery pack 531 includes a layer 519 between the antenna 517 and the secondary battery 513. Layer 519, for example, has the function of shielding electromagnetic fields from the secondary battery 513. A magnetic material can be used, for example, as layer 519.

[0237] The secondary battery 513 may also include a wound battery element. The wound battery element is formed by stacking a negative electrode and a positive electrode with a separator in between to form a laminate, and is formed by winding the laminate.

[0238] This embodiment can be appropriately combined with descriptions of other embodiments.

[0239] (Implementation Method 5) In this embodiment, an example of installing an energy storage system according to one aspect of the present invention in a vehicle is shown. Examples of vehicles include automobiles, two-wheeled vehicles, and bicycles.

[0240] When an energy storage system is installed in a vehicle, it enables a new generation of clean energy vehicles, such as hybrid electric vehicles (HEVs), electric vehicles (EVs), or plug-in hybrid electric vehicles (PHEVs).

[0241] Figure 19 illustrates a vehicle using an energy storage system according to one aspect of the present invention. Figure 19A The illustrated vehicle 8400 is an electric vehicle that uses an electric motor as its power source for driving. Alternatively, vehicle 8400 is a hybrid vehicle that can appropriately use an electric motor or an engine as its power source for driving. By using one aspect of the present invention, a vehicle with a long driving range can be realized. In addition, vehicle 8400 is equipped with an energy storage system. The energy storage system not only drives the electric motor 8406, but can also supply electricity to lighting devices such as headlights 8401 or interior lights (not shown).

[0242] In addition, the energy storage system can supply power to display devices such as the speedometer and tachometer in the car 8400. Furthermore, the energy storage system can supply power to navigation systems and other systems in the car 8400.

[0243] exist Figure 19B In the car 8500 shown, the energy storage system 8024 of the car 8500 can be charged by receiving power from an external charging device using a plug-in or contactless power supply method. Figure 19B This illustration shows a scenario where a ground-mounted charging device 8021 charges an energy storage system 8024 installed in a vehicle 8500 via a cable 8022. During charging, the charging method and connector specifications can appropriately utilize methods prescribed by CHAdeMO (registered trademark) or "Combined Charging System." The charging device 8021 can also utilize power from charging stations in commercial facilities or from a home. For example, the energy storage system 8024 installed in the vehicle 8500 can be charged by using plug-in technology to supply power from an external source. AC power can be converted to DC power using a conversion device such as an AC-DC converter for charging.

[0244] Alternatively, although not illustrated, the receiving device can be installed in the vehicle and charged by receiving power from a ground-based power supply device without contact. When using a contactless power supply method, by assembling the power supply device in the road or exterior wall, charging can be performed both when the vehicle is parked and while it is in motion. Furthermore, this contactless power supply method can also be used for power transmission and reception between vehicles. Moreover, solar cells can be installed on the exterior of the vehicle to charge the energy storage system when parked or in motion. Such contactless power supply can be achieved using electromagnetic induction or magnetic field resonance.

[0245] also, Figure 19C This is an example of a two-wheeled vehicle using an energy storage system according to one aspect of the present invention. Figure 19C The illustrated miniature motorcycle 8600 includes an energy storage system 8602, a rearview mirror 8601, and turn signals 8603. The energy storage system 8602 can supply power to the turn signals 8603.

[0246] In addition, Figure 19C In the illustrated miniature motorcycle 8600, the battery storage system 8602 can be stored in the under-seat storage compartment 8604. Even if the under-seat storage compartment 8604 is small, the battery storage system 8602 can still be stored in it.

[0247] in addition, Figure 20A An example of an electric bicycle using an energy storage system according to one aspect of the present invention is shown. Figure 20A The electric bicycle 8700 shown can use an energy storage system according to one aspect of the present invention. An energy storage system according to one aspect of the present invention includes, for example, multiple batteries, a protection circuit, and a neural network.

[0248] The electric bicycle 8700 includes a power storage system 8702. The power storage system 8702 supplies power to the electric motor that assists the rider. Furthermore, the power storage system 8702 is portable. Figure 20B A battery storage system 8702 removed from a bicycle is shown. The battery storage system 8702 incorporates a battery 8701, which is included in a battery storage system according to one embodiment of the present invention, and the remaining power level can be displayed by a display unit 8703. Furthermore, the battery storage system 8702 includes a control circuit 8704 according to one embodiment of the present invention. The control circuit 8704 is electrically connected to the positive and negative terminals of the battery 8701. The battery protection circuit shown in the above embodiment can be used as the control circuit 8704.

[0249] This implementation method can be appropriately combined with other implementation methods.

[0250] (Implementation Method 6) In this embodiment, an example of installing the energy storage system shown in the above embodiment in an electronic device will be described.

[0251] then, Figure 21A and Figure 21B An example of a tablet terminal (including a clamshell type terminal) that can be folded in half is shown. Figure 21A and Figure 21B The illustrated tablet terminal 9600 includes a frame 9630a, a frame 9630b, a movable part 9640 connecting the frames 9630a and 9630b, a display unit 9631, a display mode switching switch 9626, a power switch 9627, a power saving mode switching switch 9625, a fastener 9629, and an operation switch 9628. By using a flexible panel for the display unit 9631, a tablet terminal with a larger display unit can be realized. Figure 21A This indicates that the tablet terminal 9600 is open. Figure 21B This shows the status of the tablet terminal 9600 when closed.

[0252] Additionally, the tablet terminal 9600 has a battery 9635 inside the housings 9630a and 9630b. The battery 9635 is disposed in the housings 9630a and 9630b through the movable part 9640.

[0253] In the display unit 9631, a portion of it can be used as a touchscreen area, and data can be input by touching the displayed operation keys. Furthermore, keyboard buttons can be displayed on the display unit 9631 by touching the location of the keyboard display toggle buttons on the touchscreen using a finger or stylus.

[0254] In addition, the display mode switch 9626 can switch between portrait and landscape display orientations, as well as between monochrome and color display. Based on the amount of ambient light detected by the light sensor built into the tablet terminal 9600, the power-saving mode switch 9625 can set the display brightness to the most suitable level. Besides the light sensor, the tablet terminal can also incorporate other detection devices such as a gyroscope and an accelerometer to detect tilt.

[0255] Figure 21B The tablet terminal is in a folded state, and the tablet terminal includes a frame 9630, a solar cell 9633, and a power storage system according to one aspect of the present invention. The power storage system includes a control circuit 9634 and a power storage element 9635. The battery protection circuit shown in the above embodiment can be used as the control circuit 9634.

[0256] Furthermore, the tablet terminal 9600 can be folded in half, so when not in use, the frames 9630a and 9630b can be folded in an overlapping manner. By folding the frames 9630a and 9630b, the display unit 9631 can be protected, thereby improving the durability of the tablet terminal 9600.

[0257] also, Figure 21A and Figure 21B The tablet terminal shown may also have the following functions: displaying various types of information (static images, dynamic images, text images, etc.); displaying calendars, dates, or times on the display; touch input for touch input or editing of information displayed on the display; and control processing through various software (programs), etc.

[0258] By utilizing solar cells 9633 mounted on the surface of the tablet terminal, power can be supplied to the touchscreen, display unit, or image signal processing unit, etc. Note that solar cells 9633 can be disposed on one or both surfaces of the frame 9630, which can efficiently charge the energy storage unit 9635.

[0259] In addition, Figure 21A and Figure 21B The description indicates that the control circuit using the battery protection circuit shown in the above embodiment is used in a structure for a foldable tablet terminal; however, other structures can also be used. For example, such as... Figure 21C As shown, it can be used on a laptop PC as a clamshell terminal. Figure 21C A notebook computer 9601 is shown, which includes a display unit 9631 in a frame 9630a and a keyboard unit 9641 in a frame 9630b. The notebook computer 9601 includes... Figure 21A and Figure 21B The control circuit 9634 and the energy storage device 9635 are described. The control circuit 9634 can be the battery protection circuit shown in the above embodiment.

[0260] Figure 22 Examples of other electronic devices are shown. Figure 22 In this embodiment, the display device 8000 is an example of an electronic device equipped with a power storage system according to one aspect of the present invention. Specifically, the display device 8000 corresponds to a television broadcast receiving display device, including a housing 8001, a display unit 8002, a speaker unit 8003, and a secondary battery 8004, etc. A detection system according to one aspect of the present invention is provided inside the housing 8001. The display device 8000 can receive power from a commercial power source and also utilize the power stored in the secondary battery 8004.

[0261] As the display unit 8002, semiconductor display devices such as liquid crystal display devices, light-emitting devices having light-emitting elements such as organic EL elements in each pixel, electrophoretic display devices, DMD (Digital Micromirror Device), PDP (Plasma Display Panel), and FED (Field Emission Display) can be used.

[0262] In addition, the voice input device 8005 also uses a rechargeable battery. The voice input device 8005 includes the power storage system described in the above embodiment. Besides wireless communication elements, the voice input device 8005 also includes multiple sensors (optical sensor, temperature sensor, humidity sensor, barometric pressure sensor, illuminance sensor, motion sensor, etc.) including a microphone, which can operate other devices according to user commands, such as controlling the power supply of the display device 8000 and adjusting the light intensity of the lighting device 8100. The voice input device 8005 allows operation of peripheral devices via sound, thus replacing a manual remote control.

[0263] In addition, the voice input device 8005 includes wheels or a mechanical movement unit that moves in the direction of hearing the user's voice and correctly understands commands by a built-in microphone, and displays its contents on the display unit 8008 or can perform touch input operations on the display unit 8008.

[0264] Additionally, the voice input device 8005 can be used as a charging base for portable information terminals 8009 such as smartphones. Both the portable information terminal 8009 and the voice input device 8005 can receive power via wired or wireless means. Since the portable information terminal 8009 is not particularly necessary to carry indoors, and it is necessary to avoid putting excessive load on the secondary battery to prevent deterioration while ensuring sufficient capacity, it is preferable to use the voice input device 8005 for secondary battery management and maintenance. Furthermore, the voice input device 8005 includes a speaker 8007 and a microphone, so hands-free calling is possible even while the portable information terminal 8009 is charging. Moreover, when reducing the capacity of the secondary battery in the voice input device 8005, it can be wirelessly charged by moving it in the direction of the arrow and connecting it to an external power source via the charging module 8010.

[0265] Alternatively, the audio input device 8005 can be placed on a table. Furthermore, the audio input device 8005 can be equipped with wheels or a mechanical moving unit to move to a desired location, or the audio input device 8005 can be fixed to a desired location, such as on the floor, without a table or wheels.

[0266] In addition to display devices for receiving television broadcasts, display devices also include all display devices for displaying information, such as display devices for personal computers or display devices for advertising.

[0267] exist Figure 22 In this context, the recessed lighting device 8100 is an example of an electronic device that uses a secondary battery 8103 controlled by a microprocessor (including an APS) for charging. Specifically, the lighting device 8100 includes a frame 8101, a light source 8102, and a secondary battery 8103, etc. Although in Figure 22 The illustration shows a secondary battery 8103 installed inside a ceiling 8104 containing a frame 8101 and a light source 8102, but the secondary battery 8103 can also be installed inside the frame 8101. The lighting device 8100 can receive power from a commercial power source or use the power stored in the secondary battery 8103.

[0268] In addition, although Figure 22 An example is shown of an inlaid lighting fixture 8100 installed on the ceiling 8104, but the secondary battery 8103 can be used for inlaid lighting fixtures installed outside the ceiling 8104, such as on a side wall 8105, floor 8106, or window 8107, and can also be used for tabletop lighting fixtures, etc.

[0269] Furthermore, as the light source 8102, an artificial light source that artificially generates light using electricity can be used. Specifically, examples of the aforementioned artificial light sources include incandescent bulbs, fluorescent lamps, and other discharge lamps, as well as light-emitting elements such as LEDs or organic EL elements.

[0270] exist Figure 22 In this context, an air conditioner with an indoor unit 8200 and an outdoor unit 8204 is an example of an electronic device using a secondary battery 8203. Specifically, the indoor unit 8200 includes a frame 8201, an air outlet 8202, and a secondary battery 8203, etc. Although in Figure 22 The illustration shows a secondary battery 8203 installed in the indoor unit 8200, but the secondary battery 8203 can also be installed in the outdoor unit 8204. Alternatively, the secondary battery 8203 can be installed in both the indoor unit 8200 and the outdoor unit 8204. The air conditioner can receive power from a commercial power source or use the power stored in the secondary battery 8203.

[0271] exist Figure 22 In this example, the electric refrigerator / freezer 8300 is an example of an electronic device using a secondary battery 8304. Specifically, the electric refrigerator / freezer 8300 includes a frame 8301, a refrigerator door 8302, a freezer door 8303, and a secondary battery 8304, etc. Figure 22In this configuration, a secondary battery 8304 is located inside the housing 8301. The electric refrigerator / freezer 8300 can receive power from a commercial power source or use the power stored in the secondary battery 8304.

[0272] Furthermore, during periods when electronic devices are not used, especially when the ratio of actual electricity used to the total electricity available from commercial power sources (referred to as electricity usage rate) is low, electricity is stored in secondary batteries, thereby suppressing increased electricity usage during other periods. For example, in the case of an electric refrigerator / freezer 8300, electricity is stored in secondary batteries 8304 at night when the temperature is low and the refrigerator door 8302 or freezer door 8303 is not opened or closed. During the day when the temperature is high and the refrigerator door 8302 or freezer door 8303 is opened or closed, secondary batteries 8304 are used as auxiliary power, thereby suppressing daytime electricity usage.

[0273] The secondary battery is not limited to being installed in the aforementioned electronic devices, but can be installed in all electronic devices. By employing one aspect of the present invention, the cycle characteristics of the secondary battery can be improved. Therefore, by installing a microprocessor (including an APS) controlling the charging according to one aspect of the present invention in the electronic device described in this embodiment, an electronic device with a longer service life can be realized. This embodiment can be implemented in appropriate combinations with other embodiments.

[0274] first, Figures 23A to 23E Examples of installing a power storage system according to one aspect of the present invention in an electronic device are shown. Examples of electronic devices to which the power storage system according to one aspect of the present invention is applied include television sets (also called televisions or television receivers), displays for computers, digital cameras, digital video cameras, digital photo frames, mobile phones (also called mobile phones or mobile phone devices), portable game consoles, portable information terminals, sound reproduction devices, pinball machines, and other large-scale game machines.

[0275] Figure 23A An example of a mobile phone is shown. The mobile phone 7400, in addition to a display unit 7402 assembled in a housing 7401, also includes operation buttons 7403, an external connection port 7404, a speaker 7405, a microphone 7406, etc. Furthermore, the mobile phone 7400 has a power storage system according to one aspect of the present invention. This power storage system, for example, includes a battery 7407 and a battery protection circuit as shown in the above embodiment.

[0276] Figure 23BThe image shows the mobile phone 7400 bent. When the mobile phone 7400 is deformed by external force and bent as a whole, the battery 7407 housed inside it may also be bent. In this case, a flexible battery is preferably used as the battery 7407. Figure 23C The diagram shows a flexible battery in a bent state. The battery is electrically connected to a control circuit 7408. The control circuit 7408 can be a battery protection circuit as described in the above embodiment.

[0277] In addition, flexible batteries can be assembled along the curved surfaces of the interior or exterior walls of houses and high-rise buildings, or the interior or exterior of automobiles.

[0278] Figure 23D An example of a bracelet-type display device is shown. The portable display device 7100 includes a frame 7101, a display section 7102, operation buttons 7103, and a power storage system according to one aspect of the present invention. The power storage system according to one aspect of the present invention includes, for example, a battery 7104 and a battery protection circuit as shown in the above embodiment.

[0279] Figure 23E This is an example of a wristwatch-type portable information terminal. The portable information terminal 7200 includes a frame 7201, a display unit 7202, a strap 7203, a buckle 7204, operation buttons 7205, input / output terminals 7206, etc.

[0280] The portable information terminal 7200 can run various applications such as mobile phone, email, article reading and writing, music playback, network communication, and computer games.

[0281] The display surface of the display unit 7202 is curved, allowing for display along the curved surface. Furthermore, the display unit 7202 is equipped with a touch sensor, allowing operation via touch of the screen using a finger or stylus. For example, touching the icon 7207 displayed on the display unit 7202 can launch an application.

[0282] In addition to setting the time, the operation button 7205 can also have various functions such as power switch, wireless communication switch, setting and canceling silent mode, and setting and canceling power saving mode. For example, the functions of the operation button 7205 can be freely configured by utilizing the operating system assembled in the portable information terminal 7200.

[0283] In addition, the portable information terminal 7200 can perform short-range wireless communication that is standardized by communication protocols. For example, hands-free calling can be made by communicating with a wirelessly wireless headset.

[0284] Furthermore, the portable information terminal 7200 has an input / output terminal 7206, which allows it to directly send data to or receive data from other information terminals via a connector. It can also be charged via the input / output terminal 7206. Alternatively, charging can be performed wirelessly without using the input / output terminal 7206.

[0285] The portable information terminal 7200 includes a power storage system according to one aspect of the present invention. The power storage system includes a battery and a battery protection circuit as shown in the above embodiment.

[0286] The portable information terminal 7200 preferably includes sensors. Examples of preferred sensors include fingerprint sensors, pulse sensors, body temperature sensors, touch sensors, pressure sensors, and accelerometers.

[0287] This embodiment can be appropriately combined with descriptions of other embodiments. [Example]

[0288] [Example 1]

[0289] In this embodiment, an example of the structure of a switching switch in a actually manufactured battery protection circuit will be described. In this embodiment, the circuit is manufactured using a switching switch with… Figure 11C The switching switch 13G, which is composed of transistor 25 with back gate electrode shown, is described, and the evaluation results are explained.

[0290] Figure 24A A top view of the toggle switch 13G is shown. Figure 24A In the diagram, an X-shaped area 26 is shown, which contains multiple transistors 25 for controlling the electrical connections between terminals 16A and 16B, and between terminals 17A and 17B. Terminals 16A and 16B are electrically connected and used as terminals 16. Terminals 17A and 17B are electrically connected and used as terminals 17. Note that terminals 16A and 16B, and terminals 17A and 17B shown in the top view can be used as electrodes for connecting to external wiring.

[0291] Note that, preferably, the shape of the electrodes used as terminals 16 and 17, as seen from the top surface, is such that the distance from the external connection wiring to region 26 is equally spaced. For example, a circular shape or... Figure 24A The triangle shape shown. In addition, in the area where terminals 16A and 16B or terminals 17A and 17B, which are used as the drain side of transistor 25, are provided, it is preferable to design them to be wider than area 26, thereby reducing wiring resistance and improving heat dissipation to mitigate the heat generated by current flow.

[0292] Region 26 is equipped with multiple transistors 25. Figure 24B Showing the corresponding Figure 24A The diagram shows a top view of area 26. Figure 24B In this embodiment, an oxide 530 as described in Embodiment 2 is disposed between comb-shaped electrodes extending from terminals 16A and 17B.

[0293] Note that, as Figure 25A As shown, multiple island-shaped oxide 530Is are disposed between the electrodes shown at terminals 16 and 17 in a semiconductor layer composed of oxide 530. By employing this structure, non-uniformity in the electrical characteristics of transistor 25 can be suppressed.

[0294] Figure 25B The electrodes used as terminals 16 and 17 are shown in dashed lines. Figure 25B The diagram shows a conductor 560 used as a gate electrode and a conductor 503 used as a back gate electrode, which are disposed in a manner overlapping with the island-shaped oxide 530I.

[0295] in addition, Figure 26A Show Figure 25B A 3D view of transistor 25 in the X and Y directions. Figure 26A The image shows conductors 560 and 503 arranged in a manner overlapping with the island-shaped oxide 530I. Figure 26B In the diagram, the conductor 503, which will be used as the back gate electrode, is shown as electrode BGE. Figure 26B In the diagram, the conductor 560, which will be used as the top gate electrode, is shown as electrode TGE. Figure 26B In the diagram, one of the island-shaped oxides 530I separated by conductors 503 and 560 is shown as terminal 16, and the other is shown as terminal 17. It can be... Figure 26A The transistor shown is Figure 26B The symbols shown.

[0296] right Figure 26A , Figure 26B The electrical characteristics of the transistor 25 shown will be explained. Figure 27 The diagram illustrates the temperature dependence of the drain current (Id), one of the electrical characteristics of a transistor, which varies based on the voltage applied to the gate electrode (gate voltage: Vg) and the voltage applied to the back gate electrode (back gate voltage: Vbg). Note that the transistor used in the measurements had a channel length of 0.350 μm and a channel width of 0.350 μm. The measurement temperatures were 30°C, 85°C, 125°C, and 150°C. The drain voltage was 0.1 V. Figure 27 In this method, the changes in gate voltage and back gate voltage are treated as the same voltage, and the drain current is displayed logarithmically for graphical representation.

[0297] like Figure 27 As shown, as the temperature rises from 30°C to 150°C, the transistor characteristic of the drain current not decreasing but constantly increasing is obtained.

[0298] exist Figure 28 The diagram illustrates the temperature dependence of drain current variations based on gate and back gate voltages, where the gate and back gate voltage variations are treated as the same voltage, and the drain current is plotted as a linear representation. Measurements were taken at 30°C, 85°C, 125°C, and 150°C. The drain voltage was 0.1V.

[0299] like Figure 28 As shown, as the temperature rises from 30°C to 150°C, the transistor characteristic of the drain current not decreasing but constantly increasing is obtained.

[0300] exist Figure 29 The diagram illustrates the temperature dependence of drain current variations based on drain voltage, where variations in gate and back gate voltages are treated as the same voltage, and the drain current is plotted as a linear representation. Measurements were taken at 30°C, 85°C, 125°C, and 150°C. The gate and back gate voltages were both 1.0V.

[0301] like Figure 29 As shown, as the temperature rises from 30°C to 150°C, the transistor characteristic of the drain current not decreasing but constantly increasing is obtained.

[0302] exist Figure 30 The diagram shows the drain current based on the drain voltage when the gate voltage varies in 0.5V increments from 3.5V to 8.5V, with the back gate voltage at 0V (i.e., single-gate drive). Measurements were taken at room temperature (25°C), with the package temperature at 55°C due to self-heating.

[0303] like Figure 30 As shown, although the drain current increases with the gate voltage from 3.5V to 8.5V, good output characteristics are achieved at all voltages.

[0304] exist Figure 31 The diagram shows the drain current based on the drain voltage when both the back gate voltage and the gate voltage vary in 0.5V increments from 3.5V to 8.5V, i.e., in the case of dual-gate drive. Measurements were taken at room temperature (25°C), with the package temperature reaching 56°C due to self-heating.

[0305] like Figure 31 As shown, although the drain current increases with the back gate voltage and the gate voltage from 3.5V to 8.5V, good output characteristics are achieved at all voltages.

[0306] exist Figure 32 The diagram illustrates the variation of drain current based on gate voltage and back gate voltage, where the variations in gate voltage and back gate voltage are treated as the same voltage, and the drain current during dual-gate drive is graphically expressed logarithmically. The measurement temperature was 30°C.

[0307] like Figure 32 As shown, the transistor characteristics of extremely low off-state current and rapid drain current change are obtained. Note that... Figure 32 In this context, "Comp: 1mA" refers to the measurement data when the upper limit of the current value that the measuring device can measure is set to 1mA. This also applies to... Figure 33 .

[0308] exist Figure 33 The diagram shows the drain current variation based on the gate voltage during dual-gate drive, where the back gate voltage varies in increments of -0.5V from 0V to -1.5V. The measurement was performed at a temperature of 30°C.

[0309] like Figure 33 As shown, it can be seen that as the back gate voltage drops from 0V to -1.5V, the Id-Vg curve shifts in the positive direction and can switch threshold voltage and other transistor characteristics.

[0310] exist Figure 34 The diagram illustrates the variation of drain current based on gate voltage and back gate voltage, where the variations in gate voltage and back gate voltage are treated as the same voltage, and the drain current is graphically expressed logarithmically. The measured temperatures were 27°C, 85°C, 125°C, and 150°C.

[0311] like Figure 34 As shown, although the off-state current increases with temperature, good output characteristics are achieved under all temperature conditions.

[0312] The transistor described above, which incorporates oxide semiconductor in its semiconductor layer, can switch its electrical characteristics by controlling the back gate voltage. Specifically, it can switch between a state where a large current flows and a state where the off-state current is extremely low. Therefore, a battery protection circuit capable of low power consumption can be obtained. [Example 2]

[0313] In this embodiment, the relationship between the channel length L and channel width W of an OS transistor according to one aspect of the present invention and the reliability of the OS transistor is explained. Specifically, the reliability of the OS transistor is evaluated by assessing the behavior of ΔVsh during a +GBT (Gate Bias Temperature) stress test and the noise of the drain current of the OS transistor.

[0314] <Regarding the behavior of ΔVsh in +GBT stress testing of OS transistors> The following explains the behavior of ΔVsh during the +GBT stress test of the OS transistor.

[0315] Note that in the following description, the drift voltage (Vsh) is defined as: the Vg at which the tangent line at the point of greatest slope on the drain current (Id) vs. gate voltage (Vg) curve of the transistor intersects the straight line where Id = 1 pA. Furthermore, the change in drift voltage is represented by ΔVsh.

[0316] In +GBT stress testing of OS transistors, ΔVsh sometimes drifts in the negative direction over time. Additionally, ΔVsh sometimes exhibits behavior that varies in both the negative and positive directions but not in the negative direction. Note that in this specification, etc., the above behavior is sometimes referred to as a sawtooth behavior in +GBT stress testing.

[0317] First, the calculation method for the variation (sometimes called sawtooth amount) of the sawtooth action in the +GBT stress test is explained. Here, we consider the variation at time T in the +GBT stress test. i (i is an integer greater than or equal to 1 and less than or equal to N) The case of measuring the Id-Vg curve.

[0318] From time T1 to time T N The number of times the Id-Vg curve is measured during the period is set to N (N is an integer greater than or equal to 2). At this time, the measurement will begin from time T. i The ΔVsh value calculated from the measured Id-Vg curve is set as v. i Additionally, at time T... i The smoothed ΔVsh value using a moving average filter is set to u. i Note that there are simple moving averages, weighted moving averages, and exponential moving averages; any of these can be used. In this embodiment, a simple moving average is used.

[0319] Furthermore, if the Id-Vg curve cannot be measured before time T1, u cannot be calculated at or near time T1. i Therefore, v cannot be made i The number of u i The number of terms is consistent. Specifically, when using k (where k is an integer greater than or equal to 1 and less than (N-1) / 2) to represent the number of terms M when averaging is 2k+1 or 2k, time T1 and its vicinity refer to time T where i is greater than or equal to 1 and less than k. i Therefore, at and around time T1, u is calculated by reducing the number of terms M when taking the average. i Specifically, at and around time T1, the number of terms is reduced to 2i-1 to compute u.i Therefore, v can be made i The number of u i The number of them is the same.

[0320] Furthermore, at time T N If the Id-Vg curve cannot be measured afterward, it cannot be measured at time T. N Calculate u in and its vicinity i Therefore, v cannot be made i The number of u i The number of terms is consistent. Specifically, when using k denoted by M, where the number of terms M when averaging is 2k+1 or 2k, time T... N "And its vicinity" refers to the time T where i is greater than or equal to N-k+1 and less than or equal to N. i Therefore, at time T N Calculate u by reducing the number of terms M when taking the average, and in its vicinity. i Specifically, at time T N In its vicinity, the number of terms is reduced to 2(Ni)+1 to calculate u. i Therefore, v can be made i The number of u i The number of them is the same.

[0321] From time T1 to time T N The standard deviation σ of ΔVsh calculated from the Id-Vg curve measured during the period is calculated using the following formula. Note that in this specification, the standard deviation σ calculated using the following formula is defined as the sawtooth quantity.

[0322] [Equation 1]

[0323] The above is the calculation method for sawtooth shape quantity.

[0324] The following describes the sample used to measure the serration.

[0325] As samples, 11 different samples were manufactured, each comprising a transistor equivalent to transistor 500 shown in Figure 15, but with different channel lengths L and channel widths W. Note that each of these 11 samples comprises five transistors.

[0326] Note that in the following description of the above 11 samples, the symbols attached to the transistor 500 shown in Figure 15 are used for explanation.

[0327] Silicon oxide is used as insulator 512. Silicon nitride and aluminum oxide are used as insulator 514. Silicon oxynitride is used as insulator 516. Tantalum nitride, titanium nitride, tungsten, or a stacked structure of titanium nitride and tungsten are used as conductor 503.

[0328] Hafnium oxide formed by the ALD method is used as insulator 522. Silicon oxynitride formed by the CVD method is used as insulator 524. Note that insulator 520 is not provided in this embodiment.

[0329] As oxide 530a, a metal oxide with a film thickness of 5 nm is formed using an oxide target with an In:Ga:Zn ratio of 1:3:4 by sputtering. As oxide 530b, a metal oxide with a film thickness of 15 nm is formed using an oxide target with an In:Ga:Zn ratio of 4:2:4.1 by sputtering.

[0330] Tantalum nitride formed by sputtering is used as conductors 542a and 542b. Additionally, an insulator 544 employs a stacked structure of aluminum oxide formed by sputtering and aluminum oxide formed by ALD. Furthermore, an insulator 580 employs a stacked structure of silicon oxide formed by sputtering and silicon oxynitride formed by CVD.

[0331] As oxide 530c, it is a stacked structure of metal oxide formed by sputtering an oxide target with an In:Ga:Zn ratio of 4:2:4.1 and an oxide target with an In:Ga:Zn ratio of 1:3:4.

[0332] Silicon oxynitride formed by CVD is used as the insulator 550. Titanium nitride formed by CVD is used as the conductor 560a. Furthermore, tungsten formed by CVD is used as the conductor 560b.

[0333] As insulator 574, a multilayer structure of alumina formed by ALD and silicon nitride formed by sputtering is used. Furthermore, as insulator 581, silicon oxynitride formed by CVD is used.

[0334] Among the 11 samples mentioned above, the sample group with the same designed channel length L and channel width W (L / W = 70nm / 70nm, L / W = 80nm / 80nm, L / W = 100nm / 100nm, L / W = 200nm / 200nm, and L / W = 350nm / 350nm) is denoted as sample group A. Additionally, among the 11 samples mentioned above, the sample group with a designed channel width W of 60nm (L / W = 60nm / 60nm, L / W = 70nm / 60nm, L / W = 80nm / 60nm, L / W = 100nm / 60nm, L / W = 200nm / 60nm, and L / W = 350nm / 60nm) is denoted as sample group B.

[0335] The above is a description of the 11 samples mentioned above.

[0336] Next, the Id-Vg curves of five transistors from each of the 11 manufactured samples were measured. That is, the sawtooth pattern of 55 transistors was calculated. Note that the temperature for measuring the Id-Vg curves was set to 150°C, the drain potential Vd to 2.5V, the back gate potential Vbg to 0V, the source potential Vs to 0V, and the gate potential Vg was scanned from -3.3V to +3.3V in increments of 0.1V.

[0337] ΔVsh is calculated from the Id-Vg curve obtained from the above measurements, and the sawtooth amount of each transistor is also calculated.

[0338] Figure 35 The results show the dependence of the channel length L and channel width W on the measurement of the sawtooth profile. Figure 35 In the figure, the horizontal axis represents the reciprocal of the channel length L (1 / L) [1 / μm], and the vertical axis represents the serration amount [mV]. Furthermore, Figure 35 The circles in the diagram represent the measurement results of sample group A (a sample group where the design values ​​for the channel length and channel width of the transistor are equal). Figure 35 The squares in the diagram represent the measurement results of sample group B (sample group with a designed channel width W of 60 nm for transistors).

[0339] from Figure 35 It is evident that the longer the channel length L, the smaller the serration amount. Furthermore, it is evident that the smaller the serration amount, the less unevenness of the serration amount.

[0340] As described above, when miniaturizing transistors, a longer channel length L is preferable. For example, the channel length L of a transistor is preferably 80 nm or more and 400 nm or less, more preferably 100 nm or more and 350 nm or less. This allows for a reduction in the transistor's footprint while maintaining its reliability.

[0341] <Regarding the noise of drain current in OS transistors> The noise of the drain current of the OS transistor is explained below.

[0342] One cause of noise in transistor drain current is 1 / f noise. 1 / f noise refers to the frequency component of current fluctuations that increases inversely with frequency f. Models for 1 / f noise include those attributing it to carrier concentration fluctuations and those attributing it to mobility fluctuations. In the model attributing 1 / f noise to carrier concentration fluctuations, electrons are assumed to be bound to or released from defects. That is, reducing the defect state density can reduce 1 / f noise.

[0343] The noise of the drain current of a transistor can be expressed using the spectral density S of the noise power of the drain current. Id The value normalized by drain current Id (S) Id / Id 2 The value is obtained from the 1 / f noise measurement system and is used for evaluation.

[0344] In this embodiment, an Agilent Technologies 1 / f noise measurement system was used to measure the noise of the transistor's drain current. An Agilent B1500A was used as the semiconductor device analyzer, and an Agilent E5052B was used as the signal source analyzer. A Cascade Microtech SUMMIT 11000B-M prober (with temperature control (213K to 473K)) was used. Measurements were performed in a dark environment. The measurement range was within the specifications of the measuring instruments for voltage and current (200V / 1A or 100V / 100mA) and frequency (5Hz to 40MHz).

[0345] Next, the samples evaluated using the 1 / f noise measurement system will be described.

[0346] As the above samples, six samples (sample group C) were manufactured, each including a transistor equivalent to the transistor 500 shown in Figure 15, but with different channel lengths and channel widths.

[0347] Note that in the following description of sample group C, the symbols used for transistor 500 shown in FIG15 will be used. Furthermore, the differences between sample group C and sample groups A and B will be explained primarily, while the similarities will be omitted.

[0348] The transistors in each sample in the above sample group C include metal oxides formed by sputtering an oxide target with an In:Ga:Zn ratio of 1:3:4 [atomic number ratio] between oxide 530b and conductor 542a.

[0349] The design values ​​of the channel length L and the channel width W of the transistors in each sample in the sample group C are L / W = 60nm / 60nm, L / W = 80nm / 80nm, L / W = 100nm / 100nm, L / W = 350nm / 350nm, L / W = 100nm / 60nm, and L / W = 350nm / 60nm, respectively.

[0350] The above is an explanation of sample group C.

[0351] Next, the evaluation results of the noise of the drain current of the transistors included in each sample in the above sample group C are explained using a 1 / f noise measurement system.

[0352] Figure 36A and Figure 36B The results are shown for the transistors included in each sample in sample group C, obtained using a 1 / f noise measurement system. Figure 36A and Figure 36B In the diagram, the horizontal axis represents the noise frequency f [Hz], which ranges from 1 Hz to 100 kHz. The vertical axis represents the spectral density of the noise power of the drain current normalized to the drain current, S. Id / Id 2 [1 / Hz].

[0353] Figure 36A This refers to the sample group C containing samples where the designed channel length L of the transistor is equal to the designed channel width W (L / W = 60nm / 60nm, L / W = 80nm / 80nm, L / W = 100nm / 100nm, and L / W = 350nm / 350nm). Additionally, Figure 36B This refers to the sample group (L / W = 60nm / 60nm, L / W = 100nm / 60nm, and L / W = 350nm / 60nm) included in sample group C, where the design value of the channel width W of the transistor is 60nm.

[0354] Depend on Figure 36A and Figure 36B It can be seen that at frequencies lower than 1kHz, especially lower than 100Hz, the frequency dependence of noise is approximately proportional to 1 / f. Furthermore, the longer the channel length L of a transistor, the higher the spectral density of the noise power of the drain current normalized to the drain current (S).Id / Id 2 The smaller the tendency.

[0355] The correlation between sawtooth pattern and 1 / f noise is explained below.

[0356] The sawtooth shape of the transistors included in each sample in sample group C was calculated by measuring the Id-Vg curve of the transistor and using the sawtooth shape calculation method described above.

[0357] like Figure 36A and Figure 36B As shown, since the frequency dependence of noise on the low-frequency side is approximately proportional to 1 / f, the spectral density (Si) of the noise power is calculated using frequency f against the drain current normalized to the drain current obtained using a 1 / f noise measurement system. Id / Id 2 The value is integrated and set as an indicator of 1 / f noise. Note that the frequency f used for integration is in the range of 5 Hz to 1 kHz. Since frequencies below 5 Hz are outside the device's specifications and the reliability of the measurements is low, this range is excluded from the frequency range used for integration.

[0358] Figure 37 This is a graph illustrating the correlation between the amount of serrations and 1 / f noise in sample group C. Figure 37 In the figure, the horizontal axis represents the sawtooth quantity [mV], and the vertical axis represents the value of integrating the spectral density of the noise power of the drain current normalized to the drain current with frequency f.

[0359] from Figure 37 It can be seen that the smaller the sawtooth pattern, the smaller the 1 / f noise tends to be.

[0360] Therefore, when miniaturizing transistors, increasing the channel length L of the transistor can reduce sawtooth noise and / or 1 / f noise, thereby improving the reliability of the transistor. For example, the channel length L of the transistor is preferably 80 nm or more and 400 nm or less, more preferably 100 nm or more and 350 nm or less.

[0361] By controlling the channel length L, the OS transistor described in this embodiment can reduce 1 / f noise. Therefore, it can be appropriately used in battery protection circuits that can achieve low power consumption.

[0362] This embodiment can be implemented in appropriate combinations with the structures described in the implementation methods and other embodiments.

[0363] (Additional notes regarding the contents of this instruction manual, etc.) The following is an additional explanation of the above embodiments and the structures in the embodiments.

[0364] The structures shown in each embodiment can be appropriately combined with the structures shown in other embodiments or examples to constitute one aspect of the present invention. Furthermore, when multiple structural examples are shown in one embodiment, these structural examples can be appropriately combined.

[0365] Additionally, the content (or a portion thereof) described in one embodiment can be applied to other content (or a portion thereof) described in that embodiment and / or the content (or a portion thereof) described in one or more other embodiments; the content (or a portion thereof) described in one embodiment can be combined with other content (or a portion thereof) described in that embodiment and / or the content (or a portion thereof) described in one or more other embodiments; or the content (or a portion thereof) described in one embodiment can replace other content (or a portion thereof) described in that embodiment and / or the content (or a portion thereof) described in one or more other embodiments.

[0366] In addition, the content described in the embodiments refers to the content described with reference to the various accompanying drawings or the content described using the text in the specification.

[0367] Furthermore, more figures can be formed by combining the figures (or portions thereof) shown in one embodiment with other portions of the figures, other figures (or portions thereof) shown in that embodiment, and / or figures (or portions thereof) shown in one or more other embodiments.

[0368] Furthermore, in this specification and other documents, the constituent elements are categorized according to their functions and represented as independent blocks in the block diagram. However, there are sometimes situations where it is difficult to distinguish the constituent elements according to their functions in actual circuits, or where one circuit involves multiple functions or multiple circuits involve one function. Therefore, the blocks in the block diagram are not limited to the constituent elements described in the specification, and may be expressed in a different way as appropriate.

[0369] Furthermore, for ease of explanation, dimensions, layer thicknesses, or regions are arbitrarily shown in the accompanying drawings. Therefore, the present invention is not limited to the dimensions shown in the drawings. Moreover, the drawings are schematic for clarity and are not limited to the shapes or values ​​shown. For example, non-uniformity of signals, voltages, or currents caused by noise, or non-uniformity of signals, voltages, or currents caused by time deviations, etc.

[0370] In this specification and other materials, when describing the connection relationship of a transistor, it is referred to as "one of the source and drain" (or the first electrode or the first terminal) or "the other of the source and drain" (or the second electrode or the second terminal). This is because the source and drain of a transistor vary depending on the transistor's structure or operating conditions. Furthermore, depending on the circumstances, the source and drain of a transistor may be appropriately referred to as source (drain) terminals or source (drain) electrodes, etc.

[0371] Furthermore, in this specification and other materials, terms such as "electrode" or "wiring" do not functionally limit the constituent elements. For example, sometimes "electrode" is used as part of "wiring," and vice versa. Moreover, the terms "electrode" or "wiring" also include cases where multiple "electrodes" or "wiring" are formed as a single unit.

[0372] Furthermore, in this instruction manual and other documents, voltage and potential may be appropriately interchanged. Voltage refers to the potential difference between the voltage and a reference potential. For example, when the reference potential is ground voltage, voltage can be replaced with potential. Ground potential does not necessarily mean 0V. In addition, potential is relative, and the potential supplied to wiring, etc., sometimes varies depending on the reference potential.

[0373] Furthermore, in this specification and other materials, the terms "film" and "layer" may be interchanged depending on the circumstances. For example, the term "conductive layer" may sometimes be changed to "conductive film." Similarly, the term "insulating film" may sometimes be changed to "insulating layer."

[0374] In this specification and the like, a switch refers to a component that controls whether current flows by changing to a conducting state (on state) or a non-conducting state (off state). Alternatively, a switch refers to a component that selects and switches the path of current.

[0375] In this specification, for example, channel length refers to the distance between the source and drain in the region where the semiconductor (or the portion of the semiconductor through which current flows when the transistor is in the on state) and the gate overlap or in the region forming the channel, in a top view of the transistor.

[0376] In this specification, for example, the channel width refers to the length of the region where the semiconductor (or the portion in which current flows through the semiconductor when the transistor is in the on state) and the gate overlap, or the portion of the region in which the source and drain are opposite each other in forming the channel.

[0377] In this specification, "A and B connection" includes not only the case where A and B are directly connected, but also the case where A and B are electrically connected. Here, "A and B electrical connection" means that there are objects between A and B that have some electrical interaction, enabling the transmission and reception of electrical signals between A and B. [Symbol Explanation]

[0378] 10: Energy storage device, 10A: Energy storage device, 10B: Energy storage device, 11: Battery cell, 12: Battery protection circuit, 12A: Battery protection circuit, 12B: Battery protection circuit, 13: Switching circuit, 13A: Switching circuit, 13C: Switching circuit, 13D: Switching circuit, 13E: Switching circuit, 13F: Switching circuit, 13G: Switching circuit, 14: Terminal, 15: Terminal, 16: Terminal, 16A: Terminal, 16B: Terminal, 17: Terminal, 17A: Terminal, 17B: Terminal, 18: Voltage detection circuit, 21: Mechanical relay, 22: Mechanical relay, 23: Transistor, 23A: Transistor, 24: Transistor, 24A: Transistor, 25: Transistor, 26: Region 30: Charge / Discharge Switching Circuit; 31: Transistor; 32: Transistor; 33: Mechanical Relay; 40: Charging Control Circuit; 41: Diode Element; 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; 374 376: Insulator; 380: Insulator; 382: Insulator; 384: Insulator; 386: Conductor; 400: Secondary battery; 401: Positive electrode cover; 413: Conductive plate; 414: Conductive plate; 415: Energy storage system; 416: Wiring; 420: Control circuit; 421: Wiring; 422: Wiring; 423: Wiring; 424: Conductor; 425: Insulator; 426: Wiring; 500: Transistor; 501: Circuit board; 503: Conductor; 503a: Conductor; 503b: Conductor; 509: Label; 510: Insulator; 511: Terminal; 512: Insulator; 513: Secondary battery; 514: Insulator; 515: Sealing tape; 516: Insulator 517: Antenna; 518: Conductor; 519: Layer; 520: Insulator; 522: Insulator; 524: Insulator; 530: Oxide; 530a: Oxide; 530b: Oxide; 530c: Oxide; 530I: Oxide; 531: Secondary battery pack; 540a: Conductor; 540b: Conductor; 542a: Conductor; 542b: Conductor; 543a: Region; 543b: Region; 544: Insulator; 546: Conductor; 548: Conductor; 550: Insulator; 551: One; 552: Another; 560: Conductor; 560a: Conductor; 560b: Conductor; 574: Insulator; 580: Insulator; 581: Insulator.582: Insulator, 586: Insulator, 590: Control circuit, 590a: Circuit system, 590b: Circuit system, 600: Capacitor, 610: Conductor, 612: Conductor, 620: Conductor, 630: Insulator, 640: Insulator, 700: Electronic component, 701: Lead wire, 702: Printed circuit board, 703: Circuit section, 704: Circuit board, 7100: Portable display device, 7101: Frame, 7102: Display section, 7103: Operation button, 7104: Battery, 7200: Portable information terminal, 7201: Frame, 7202: Display section, 7203: Strap, 7204: Buckle, 720 5: Operation button; 7206: Input / output terminal; 7207: Chart; 7400: Mobile phone; 7401: Frame; 7402: Display unit; 7403: Operation button; 7404: External connection port; 7405: Speaker; 7406: Microphone; 7407: Battery; 7408: Control circuit; 8000: Display device; 8001: Frame; 8002: Display unit; 8003: Speaker unit; 8004: Secondary battery; 8005: Sound input device; 8007: Speaker; 8008: Display unit; 8009: Portable information terminal; 8010: Charging module; 8021: Charging device; 8022: Cable; 80 24: Energy storage system; 8100: Lighting fixture; 8101: Frame; 8102: Light source; 8103: Secondary battery; 8104: Ceiling; 8105: Side wall; 8106: Floor; 8107: Window; 8200: Indoor unit; 8201: Frame; 8202: Air outlet; 8203: Secondary battery; 8204: Outdoor unit; 8300: Electric refrigerator / freezer; 8301: Frame; 8302: Refrigerator door; 8303: Freezer door; 8304: Secondary battery; 8400: Automobile; 8401: Headlight; 8406: Electric motor; 8500: Automobile; 8600: Motorcycle; 8601: Rearview mirror; 8602: Energy storage. System, 8603: Turn signals, 8604: Under-seat storage, 8700: Electric bicycle, 8701: Battery, 8702: Energy storage system, 8703: Display unit, 8704: Control circuit, 9600: Tablet terminal, 9601: Notebook computer, 9625: Switch, 9626: Switch, 9627: Power switch, 9628: Operating switch, 9629: Fastener, 9630: Frame, 9630a: Frame, 9630b: Frame, 9630B: Frame, 9631: Display unit, 9633: Solar cell, 9634: Control circuit, 9635: Energy storage unit, 9640: Movable part, 9641: Keyboard unit,

Claims

1. A battery protection circuit, comprising: A switching circuit used to control the charging and discharging of battery cells. The switching circuit includes a mechanical relay, a first transistor, and a second transistor. The switching circuit has the function of switching between the first current path and the second current path. The first current path is the current path between the first transistor and the mechanical relay connected in series between the first terminal and the second terminal. The second current path is the current path between the first terminal and the second terminal through the second transistor. The mechanical relay has the function of interrupting the electrical connection of the first current path. The first transistor has the function of allowing a first current to flow through the first current path between the first terminal and the second terminal. The second transistor has the function of allowing a second current to flow through the second current path between the first terminal and the second terminal. Furthermore, the first current is greater than the second current.

2. A battery protection circuit, comprising: A switching circuit used to control the charging and discharging of battery cells. The switching circuit includes a mechanical relay, a first transistor, and a second transistor. The switching circuit has the function of switching between the first current path and the second current path. The first current path is the current path between the first transistor and the mechanical relay connected in series between the first terminal and the second terminal. The second current path is the current path between the first terminal and the second terminal through the second transistor. The mechanical relay has the function of interrupting the electrical connection of the first current path. The first transistor has the function of allowing a first current to flow through the first current path between the first terminal and the second terminal. The semiconductor layer with the channel formation region in the first transistor is formed using silicon. The second transistor has the function of allowing a second current to flow through the second current path between the first terminal and the second terminal. The semiconductor layer with the channel formation region in the second transistor is formed using an oxide semiconductor. Furthermore, the first current is greater than the second current.

3. The battery protection circuit according to claim 1 or 2, The first current is the on-state current flowing between the source and drain of the first transistor, and the second current is the on-state current flowing between the source and drain of the second transistor.

4. The battery protection circuit according to claim 3, The first off-state current flowing between the source and the drain when the first transistor is off is greater than the second off-state current flowing between the source and the drain when the second transistor is off.

5. A battery protection circuit, comprising: A switching circuit used to control the charging and discharging of battery cells. The switching circuit includes a first terminal and a second terminal. The switching circuit includes a first transistor. The first transistor includes a back gate electrode. The switching circuit has the function of switching between a first state and a second state. When the first transistor is turned on, the amount of current flowing between the first terminal and the second terminal in the first state is greater than the amount of current flowing between the first terminal and the second terminal in the second state. When the first transistor is off, the amount of current flowing between the first terminal and the second terminal in the second state is extremely low. The first transistor can switch between a first current in the first state and a second current in the second state, flowing in the same direction between the first and second terminals during operation, by controlling the voltage applied to the back gate electrode, for charging or discharging operation. The first transistor can be turned off in the second state by controlling the voltage applied to the back gate electrode, in order to stop charging and discharging operations. Furthermore, the first current is greater than the second current.

6. An energy storage device, comprising: Battery cell; as well as A switching circuit used to control the charging and discharging of the battery cell. The switching circuit includes a mechanical relay, a first transistor, and a second transistor. The switching circuit has the function of switching between the first current path and the second current path. The first current path is the current path between the first transistor and the mechanical relay connected in series between the first terminal and the second terminal. The second current path is the current path between the first terminal and the second terminal through the second transistor. The mechanical relay has the function of interrupting the electrical connection of the first current path. The first transistor has the function of allowing a first current to flow through the first current path between the first terminal and the second terminal. The second transistor has the function of allowing a second current to flow through the second current path between the first terminal and the second terminal. Furthermore, the first current is greater than the second current.

7. An energy storage device, comprising: Battery cell; as well as A switching circuit used to control the charging and discharging of the battery cell. The switching circuit includes a mechanical relay, a first transistor, and a second transistor. The switching circuit has the function of switching between the first current path and the second current path. The first current path is the current path between the first transistor and the mechanical relay connected in series between the first terminal and the second terminal. The second current path is the current path between the first terminal and the second terminal through the second transistor. The mechanical relay has the function of interrupting the electrical connection of the first current path. The first transistor has the function of allowing a first current to flow through the first current path between the first terminal and the second terminal. The semiconductor layer with the channel formation region in the first transistor is formed using silicon. The second transistor has the function of allowing a second current to flow through the second current path between the first terminal and the second terminal. The semiconductor layer with the channel formation region in the second transistor is formed using an oxide semiconductor. Furthermore, the first current is greater than the second current.

8. The energy storage device according to claim 6 or 7, The first current is the on-state current flowing between the source and drain of the first transistor, and the second current is the on-state current flowing between the source and drain of the second transistor.

9. The energy storage device according to claim 8, The first off-state current flowing between the source and the drain when the first transistor is off is greater than the second off-state current flowing between the source and the drain when the second transistor is off.

10. An energy storage device, comprising: Battery cell; as well as A switching circuit used to control the charging and discharging of the battery cell. The switching circuit includes a first terminal and a second terminal. The switching circuit includes a first transistor. The first transistor includes a back gate electrode. The switching circuit has the function of switching between a first state and a second state. When the first transistor is turned on, the amount of current flowing between the first terminal and the second terminal in the first state is greater than the amount of current flowing between the first terminal and the second terminal in the second state. When the first transistor is off, the amount of current flowing between the first terminal and the second terminal in the second state is extremely low. The first transistor can switch between a first current in the first state and a second current in the second state, flowing in the same direction between the first and second terminals when it is turned on, by controlling the voltage applied to the back gate electrode, for charging or discharging operation. The first transistor can be turned off in the second state by controlling the voltage applied to the back gate electrode, in order to stop the operation of the energy storage device. Furthermore, the first current is greater than the second current.

11. The energy storage device according to any one of claims 6, 7, 9 and 10, further comprising: A battery protection circuit used to control the switching circuit; as well as A charging control circuit used to switch the charging mode of the battery cell. The first transistor has the function of controlling the amount of current flowing between the first terminal and the second terminal, and The battery protection circuit controls the current based on the signal from the charging control circuit.

12. The energy storage device according to claim 11, The battery protection circuit described therein has the function of controlling the amount of current in a manner that switches the charging mode from constant current charging mode to constant voltage charging mode.

13. The energy storage device according to claim 6 or 10, The first transistor contains an oxide semiconductor in the channel formation region.

14. The energy storage device according to any one of claims 6, 7, and 10, The battery cell described therein is flexible.

15. An electrical appliance, comprising: The energy storage device according to any one of claims 6, 7, 9, 10 and 12; as well as Frame.

Images