JP2022119979A - Battery protection circuit and power storage device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery protection circuit having a novel configuration, and a power storage device including the battery circuit.

SOLUTION: A power storage device includes a battery assembly including a plurality of battery cells, and a battery protection circuit. The battery protection circuit includes a comparison circuit, a reference voltage generation circuit, a control circuit, and a storage circuit. The comparison circuit has a first input terminal, a second input terminal, and an output terminal. The first input terminal is electrically connected to any one terminal of a battery cell. The second input terminal is electrically connected to the storage circuit. The storage circuit has a first transistor, and has a function of holding a voltage generated by the reference voltage generation circuit by setting the first transistor to a non-conduction state. The control circuit has a function of controlling a voltage or current to be applied to the battery assembly according to a signal of the output terminal.

SELECTED DRAWING: Figure 3

COPYRIGHT: (C)2022,JPO&INPIT

Description

One embodiment of the present invention relates to a battery protection circuit, a power storage device, and an electrical device.

Note that one embodiment of the present invention is not limited to the above technical field. The technical field of the invention disclosed in this specification and the like relates to products, methods, or manufacturing methods. Alternatively, one aspect of the invention relates to a process, machine, manufacture, or composition of matter. Therefore, the technical field of one embodiment of the present invention disclosed in this specification more specifically includes a semiconductor device, a display device, a light-emitting device, a power storage device, an imaging device, a memory device, a driving method thereof, or a driving method thereof. A manufacturing method can be mentioned as an example.

Power storage devices (also referred to as batteries or secondary batteries) have come to be used in a wide range of fields, from small electrical devices to automobiles. As the application range of batteries expands, applications using multi-cell configuration battery stacks in which a plurality of battery cells are connected in series are increasing.

A power storage device usually has a battery protection circuit in order to detect abnormalities during charging and discharging, such as overdischarge, overcharge, overcurrent, or short circuit. The battery protection circuit acquires data such as voltage and current in order to detect an abnormality during charging and discharging. The battery protection circuit performs control such as stopping charging and discharging and cell balancing based on the observed data.

Patent Document 1 discloses a protection IC that functions as a battery protection circuit. In the protection IC described in Patent Document 1, a plurality of comparators are provided inside, and a reference voltage is compared with the voltage of the terminal to which the battery is connected to detect an abnormality during charging and discharging. disclosed.

Patent Document 2 discloses a battery state detection device for detecting a micro short circuit of a secondary battery and a battery pack containing the same.

US Patent Application Publication No. 2011-267726 Japanese Patent Application Laid-Open No. 2010-66161

In order to improve the safety of the battery protection circuit, it is necessary to constantly detect abnormalities during charging and discharging. For example, a comparator in a battery protection circuit requires power for generating a reference voltage in an internal power supply circuit or power for operating the comparator.

A comparator in the battery protection circuit must be provided for each function to detect overdischarge, overcharge, overcurrent, or short circuit. Furthermore, in the case of a battery protection circuit provided in an assembled battery having a plurality of battery cells, a comparator in the battery protection circuit is required for each battery cell that is directly provided, so the required number of comparators further increases.

However, when using a transistor (Si transistor) having silicon in a channel formation region in a power supply circuit and a comparator, there is a problem that the characteristics fluctuate significantly when the temperature rises. In particular, when the battery protection circuit is exposed to a high-temperature environment due to charging/discharging of the battery cell, etc., variations in internal transistor characteristics become large. In this case, problems such as an increase in leakage current through the transistor, difficulty in normal operation due to variations in transistor characteristics, and an increase in power consumption may occur.

An object of one embodiment of the present invention is to provide a novel battery protection circuit, a power storage device, an electric device, or the like. Another object of one embodiment of the present invention is to provide a battery protection circuit, a power storage device, an electric device, or the like with a novel structure in which power consumption can be reduced.

Note that the problem of one embodiment of the present invention is not limited to the problems listed above. The issues listed above do not preclude the existence of other issues. Still other issues are issues not mentioned in this section, which will be described in the following description. Problems not mentioned in this section can be derived from the descriptions in the specification, drawings, or the like by those skilled in the art, and can be appropriately extracted from these descriptions. One aspect of the present invention is to solve at least one of the above-described problems and/or other problems.

One aspect of the present invention is a battery protection circuit for an assembled battery including a plurality of battery cells, comprising a comparison circuit, a reference voltage generation circuit, a control circuit, and a storage circuit, wherein the comparison circuit comprises: a first input terminal, a second input terminal, and an output terminal, the first input terminal being electrically connected to one of the terminals of the battery cells, and the second input terminal being connected to the storage circuit; electrically connected, the memory circuit has a first transistor and has a function of holding the voltage generated by the reference voltage generation circuit by making the first transistor non-conductive; , is a battery protection circuit having a function of controlling the voltage or current applied to the assembled battery according to the signal at the output terminal.

In one aspect of the present invention, the battery protection circuit preferably includes an oxide semiconductor in a channel formation region of the first transistor.

In one aspect of the present invention, it is preferable that the comparison circuit has a second transistor, and the second transistor is a battery protection circuit having silicon in the channel formation region.

One aspect of the present invention includes an assembled battery including a plurality of battery cells, and a battery protection circuit, wherein the battery protection circuit includes a comparison circuit, a reference voltage generation circuit, a control circuit, a storage circuit, and the comparison circuit has a first input terminal, a second input terminal, and an output terminal, the first input terminal being electrically connected to one of the terminals of the battery cells, and the first The two input terminals are electrically connected to a memory circuit, the memory circuit has a first transistor, and holds the voltage generated by the reference voltage generation circuit by turning off the first transistor. function, and the control circuit is a power storage device that has a function of controlling the voltage or current applied to the assembled battery according to the signal of the output terminal.

In one embodiment of the present invention, the power storage device preferably includes an oxide semiconductor in a channel formation region of the first transistor.

In one embodiment of the present invention, the comparison circuit preferably includes a second transistor, and the second transistor preferably has a power storage device including silicon in a channel formation region.

One embodiment of the present invention is an electrical device including the power storage device described above and a housing.

Note that another aspect of the present invention is described in the description and drawings in the following embodiments.

One embodiment of the present invention can provide a novel battery protection circuit, a power storage device, an electric device, and the like. Alternatively, one embodiment of the present invention can provide a battery protection circuit, a power storage device, an electric device, or the like with a novel structure, which can reduce power consumption.

Note that the effects of one embodiment of the present invention are not limited to the effects listed above. The effects listed above do not preclude the existence of other effects. Still other effects are effects not mentioned in this section that will be described in the following description. Effects not mentioned in this item can be derived from the descriptions in the specification, drawings, etc. by those skilled in the art, and can be appropriately extracted from these descriptions. Note that one embodiment of the present invention has at least one of the effects listed above and/or other effects. Accordingly, one aspect of the present invention may not have the effects listed above depending on the case.

1 is a block diagram illustrating one embodiment of the present invention; FIG. 1 is a block diagram illustrating one embodiment of the present invention; FIG. 1 is a block diagram illustrating one embodiment of the present invention; FIG. 1 is a block diagram illustrating one embodiment of the present invention; FIG. 1A and 1B are circuit diagrams each illustrating one embodiment of the present invention; 4A and 4B are timing charts illustrating one embodiment of the present invention; 1A and 1B are circuit diagrams each illustrating one embodiment of the present invention; FIG. 2 is a cross-sectional view showing a configuration example of a semiconductor device; FIG. 2 is a cross-sectional view showing a configuration example of a semiconductor device; 1A and 1B are a top view and a cross-sectional view of a structure example of a transistor; The flowchart figure and perspective schematic diagram which show the manufacturing process of an electronic component. 1A and 1B illustrate an electric device of one embodiment of the present invention; 1A and 1B illustrate an electric device of one embodiment of the present invention; 1A and 1B illustrate an electric device of one embodiment of the present invention; 1A and 1B illustrate an electric device of one embodiment of the present invention; 1A and 1B illustrate an electric device of one embodiment of the present invention; 1A and 1B illustrate an electric device of one embodiment of the present invention; 1A and 1B illustrate an electric device of one embodiment of the present invention;

Hereinafter, embodiments will be described with reference to the drawings. Those skilled in the art will readily appreciate, however, that the embodiments can be embodied in many different forms and that various changes in form and detail can be made therein without departing from the spirit and scope thereof. . Therefore, the present invention should not be construed as being limited to the description of the following embodiments.

In this specification and the like, the ordinal numbers "first", "second", and "third" are added to avoid confusion of constituent elements. Therefore, the number of components is not limited.
Also, the order of the components is not limited. Also, for example, the component referred to as "first" in one of the embodiments of this specification etc. is the component referred to as "second" in another embodiment or the scope of claims It is possible. Further, for example, the component referred to as "first" in one of the embodiments of this specification etc. may be omitted in other embodiments or the scope of claims.

In the drawings, the same elements, elements having similar functions, elements made of the same material, elements formed at the same time, etc. may be denoted by the same reference numerals, and repeated description thereof may be omitted.

(Embodiment 1)
A configuration of a battery protection circuit and a power storage device including the battery protection circuit will be described with reference to FIGS. 1 to 6. FIG.

FIG. 1 shows an example of a block diagram of a power storage device 100. As shown in FIG. Power storage device 10 shown in FIG.
0 is the battery protection circuit 110, the assembled battery 120, the cell balance circuit unit 130, the transistor 1
40, transistor 150 is shown.

The assembled battery 120 has a plurality of battery cells 121 as an example. In addition, in FIG. 1, the assembled battery 1
Although one battery protection circuit 110 is provided for one battery 20, a plurality of battery protection circuits may be provided for one assembled battery.

In addition, although the battery cell 121 is described as a lithium ion secondary battery cell, it is not limited to the lithium ion secondary battery cell. can be done. Element A is one or more selected from Group 1 elements and Group 2 elements. Alkali metals such as lithium, sodium, and potassium can be used as the Group 1 elements. Also, for example, calcium, beryllium, magnesium, or the like can be used as the Group 2 element. As the element X, for example, one or more selected from metal elements, silicon and phosphorus can be used. Element X is one or more selected from cobalt, nickel, manganese, iron, and vanadium. Typical examples include lithium cobalt composite oxide LiCoO ₂ and lithium iron phosphate LiFePO ₄ .

The cell balance circuit section 130 has, as an example, a plurality of resistance elements 131 and transistors 132 . The cell balance circuit unit 130 discharges the battery cell 121 by adjusting the amount of current flowing through the resistance element 131, and by bringing the transistor 132 into a conducting state by the control signal OUT1 output from the battery protection circuit 110, thereby adjusting the charging rate. adjust.

Transistor 140 and transistor 150 have a function of controlling charging or discharging to assembled battery 120 . As an example, the transistor 140 is controlled to be conductive or non-conductive by the control signal OUT2 to control whether or not to discharge the assembled battery 120 . Further, the transistor 150 is controlled to be conductive or non-conductive by the control signal OUT3, thereby controlling whether or not the battery pack 120 is charged.

The battery protection circuit 110 is a circuit for observing the voltage value (monitor voltage) of each terminal of the battery cell 121 of the assembled battery 120 and the current value (monitor current) flowing through the assembled battery. Note that FIG. 1 shows a configuration for observing the current flowing through the resistance element to measure the monitor current, but another configuration, for example, a configuration for observing the ON current of the transistor 140 or the transistor 150 as the monitor current, may be used. .

Also, the battery protection circuit 110 responds to the monitor voltage and the monitor current by controlling the control signal OUT1.
to OUT3. The battery protection circuit 110 has an arithmetic circuit that performs arithmetic processing for estimating the state of each battery cell 121 in the assembled battery 120 . Battery protection circuit 11
0 outputs a control signal for adjusting the cell balance and a signal for controlling charging or discharging according to the calculation result obtained by the calculation processing.

As a calculation means for estimating the state of the battery cell 121, calculation for calculating the charging rate using a regression model based on data such as monitor voltage and monitor current is suitable. A preferred regression model is the Kalman filter based on the equation of state.

A Kalman filter is a type of infinite impulse response filter. Multiple regression analysis is one of multivariate analyses, and multiple independent variables are used for regression analysis. The multiple regression analysis includes the method of least squares and the like. While regression analysis requires many time series of observed values, the Kalman filter has the advantage of being able to sequentially obtain optimal correction coefficients as long as a certain amount of data is accumulated. The Kalman filter can also be applied to non-stationary time series.

As a method of estimating the internal resistance and SOC (State Of Charge) of a secondary battery, a nonlinear Kalman filter (specifically, an unscented Kalman filter (UKF))
) can be used. An extended Kalman filter (also called EKF) can also be used.

In one embodiment of the present invention, a comparator (comparison circuit) that compares a voltage value observed in the battery protection circuit 110 with a voltage value to be compared (reference voltage) includes a storage circuit that holds the reference voltage. and A reference voltage is a voltage generated by a reference voltage generation circuit.
A memory circuit includes a transistor and a capacitor. The memory circuit holds the reference voltage generated by the reference voltage generation circuit by turning off the transistor.

A transistor included in a memory circuit in the battery protection circuit 110 is preferably a transistor whose channel formation region includes an oxide semiconductor (hereinafter referred to as an OS transistor).

In the structure of one embodiment of the present invention, a memory circuit including an OS transistor has extremely low leakage current (hereinafter referred to as off-state current) flowing between a source and a drain in an off state. can be stored in the memory circuit.

In addition, in a memory circuit using an OS transistor, the reference voltage can be rewritten and read by charging or discharging, so that the monitor voltage can be obtained and read virtually unlimited times. A memory circuit using an OS transistor does not involve a structural change at the atomic level, unlike a magnetic memory or a resistance change memory, and thus has excellent rewrite resistance. In addition, unlike a flash memory, a memory circuit using an OS transistor does not show instability due to an increase in electron trapping centers even in repeated rewriting operations.

In addition, since a memory circuit using an OS transistor can be freely arranged by being stacked over a circuit using a Si transistor or the like, integration can be easily performed. In addition, since an OS transistor can be manufactured using a manufacturing apparatus similar to that of a Si transistor, it can be manufactured at low cost.

When the OS transistor includes a back gate electrode in addition to a gate electrode, a source electrode, and a drain electrode, it can be a semiconductor element with four terminals. It can be composed of an electric circuit network capable of independently controlling the input and output of signals flowing between the source and the drain according to the voltage applied to the gate electrode or the back gate electrode. Therefore, the circuit can be designed with the same thinking as the LSI. In addition, OS transistors have better electrical characteristics than Si transistors in high-temperature environments. Specifically, even at a high temperature of 100° C. to 200° C., preferably 125° C. to 150° C., the on-current to off-current ratio is large, so that good switching operation can be performed.

Note that FIG. 1 illustrates the configuration in which the control signal OUT1 output from the battery protection circuit 110 is applied to the gate of the transistor 132 in the cell balance circuit section 130.
Other configurations are possible. For example, as in the power storage device 100 illustrated in FIG. 2 , the cell balance control circuit 133 may be provided in the cell balance circuit 130A and the control signal OUT1 may be provided to the cell balance control circuit 133 . The cell balance control circuit 133 is a circuit that generates a signal to be applied to the gate of the transistor 132 according to an input signal.

Note that the transistors 140 and 150 described above are also preferably formed using OS transistors. As described above, the OS transistor has characteristics such as extremely low off-state current and excellent switching characteristics even in a high-temperature environment. Therefore, even in a high-temperature environment, the charging or discharging of the assembled battery 120 can be controlled without malfunction.

Next, after giving a specific example of the assembled battery 120, a configuration example of the battery protection circuit 110 will be described.

FIG. 3A shows a schematic diagram in which six battery cells 121 are connected in series as an example of the assembled battery 120 described in FIG. Further, FIG. 3A shows seven terminals as terminals for acquiring the monitor voltage described above. The battery protection circuit 110 acquires voltages VC0 to VC6 from each terminal. The battery protection circuit 110, for example, voltages VC0 to VC6
, the variation in the charging rate among the battery cells 121 can be estimated.

FIG. 3B shows an example of a block diagram of the battery protection circuit 110 described in FIG. In FIG. 3B, a voltage comparator 11 having a comparator 113 and a memory circuit 114 is shown.
1, an arithmetic circuit 112, and a reference voltage generation circuit 115 are shown.

The voltage comparison unit 111 compares the voltages VC0 to VC6 corresponding to the monitor voltage of each battery cell with the reference voltages Vref[0] to Vref[6], and outputs the voltage level corresponding to the comparison result to the arithmetic circuit 112. It has the function to Comparator 113 included in voltage comparator 111
A first input terminal of is connected to terminals providing voltages VC0 to VC6. Also, the voltage comparator 1
A second input terminal of a comparator 113 included in 11 is connected to a storage circuit 114 .

The memory circuit 114 is a memory circuit including an OS transistor as described above. A specific circuit configuration will be described with reference to FIG. 5, which will be described later. Note that the reference voltage generation circuit 115
are reference voltages Vref[0] to Vref[6] (not shown in FIG. 3B. Vref
Also called [N]. ) is applied to the memory circuit 114 . The memory circuit 114 is
Holds electric charge corresponding to one of the reference voltages Vref[0] to Vref[6].

Note that the comparator 113 is a transistor having silicon in the channel formation region (Si
transistor). Si transistors include p-channel and n-channel transistors. The comparator 113 can be composed of complementary transistors. In addition, the Si transistor can be stacked with the OS transistor. Therefore, an increase in circuit area due to the provision of the memory circuit can be reduced.

The reference voltage generation circuit 115 is a circuit having a function of generating a plurality of reference voltages Vref[0] to Vref[6] based on an input voltage such as voltage VC6. Reference voltage Vr
ef[0] to Vref[6] may be voltages obtained by stepping down or stepping up the voltage VC6. That is, the reference voltage generation circuit 115 is a circuit that functions as a level shifter, a booster circuit, or a voltage-down circuit.

The arithmetic circuit 112 outputs the control signals OUT1 to _OUT3 (see FIG. 3B) according to the signal obtained from the output terminal of the comparator 113 and other signals SI such as the monitor current.
) has a function of outputting OUT (shown in the figure). The arithmetic circuit 112 is the comparator 11
Arithmetic processing for estimating the state of each battery cell 121 in the assembled battery 120 is performed according to the output signal of 3 and the signal _SI , and a control signal OUT is output according to the result of the arithmetic processing. The control signal OUT corresponds to the control signals OUT1 to OUT3 described above, and is a signal for controlling charging and discharging of the assembled battery 120 and adjusting cell balance.

4A and 4B are block diagrams for explaining the operation of the battery protection circuit 110 explained in FIG. 3B.

The block diagram shown in FIG. 4A corresponds to the configuration shown in FIG. 3B, partly omitted for explanation. FIG. 4A shows a switch PSW, a memory control circuit 116, and a sensor 117 in addition to the configuration shown in FIG. 3B.

The switch PSW is a switch for controlling whether or not to transmit the voltage (VC6) for operating the reference voltage generation circuit 115 to the reference voltage generation circuit 115 . Switch PSW
is controlled to be on or off by a signal SPG output from the memory control circuit 116 . The switch PSW is preferably formed using a transistor such as an OS transistor because off current can be extremely low.

Sensor 117 functions as a trigger for memory control circuit 116 to generate a signal for operating switch PSW and storage circuit 114 . The sensor 117 has, for example, a temperature sensor or a timer. The sensor 117 generates a signal for the memory control circuit 116 to intermittently operate the switch PSW and the memory circuit 114, such as when the environmental temperature changes or after a certain period of time has passed.

The memory control circuit 116 outputs a signal SP for controlling on or off of the switch _PSW .
_G , and signals S _{m_W} and S _{m_H} for controlling the operation of the memory circuit. The memory control circuit 116 has a function of outputting various control signals according to control from the sensor 117 .

In FIG. 4A, memory control circuit 116 applies reference voltage Vre to each of storage circuits 114 .
It illustrates the operation when writing f[0] to Vref[6]. In this operation, the signal SPG is used to turn on the switch _PSW . Further, in this operation, the signal _Sm is controlled so that the reference voltage generated by the reference voltage generation circuit 115 is written to the memory circuit 114 .

Also, in FIG. 4B, the memory control circuit 116 controls the reference voltage Vref in each of the storage circuits.
[0] to Vref[6] are shown. In this operation, the switch P
The signal _SPG is controlled so that SW is turned off. Further, in this operation, the reference voltage generation circuit 11
5 is controlled by the signal _Sm so that the storage circuit 114 holds the reference voltage. Therefore, the storage circuit 114 maintains the reference voltage Vref[0] even when the reference voltage generation circuit 115 is inactive.
to Vref[6] can continue to be output. Since the reference voltage generation circuit 115 can be inactive while the switch PSW is off, power consumption can be reduced.

With the structures of FIGS. 4A and 4B, the reference voltage held in the memory circuit 114 can be periodically refreshed (the original reference voltage can be rewritten). The use of an OS transistor for the memory circuit 114 that holds the reference voltage is preferable because the refresh frequency can be reduced.

FIGS. 5A to 5C are diagrams illustrating configuration examples of memory circuits 114A to 114C which can be applied to the memory circuit 114 illustrated in FIG. 3B. Note that FIGS. 5A to 5C also show the comparator 113 for the sake of explanation.

A memory circuit 114A illustrated in FIG. 5A includes a transistor MT1 and a capacitive element C[N
]. A reference voltage Vref[N] is applied to one of the source and drain of the transistor MT1.
] are connected. A gate of the transistor MT1 is connected to a wiring for applying a signal Sm. The other of the source and the drain of the transistor MT1 is connected to one electrode of the capacitor C[N] and to the inverting input terminal of the comparator 113 . Note that in FIG. 4A, a node to which one electrode of the capacitor C[N] and the inverting input terminal of the comparator 113 are connected is illustrated as a node MN. Note that the non-inverting input terminal of the comparator 113 is connected to a wiring that supplies the voltage VC[N] from the battery cell 121 .

As described above, the transistor MT1 included in the memory circuit 114A is preferably an OS transistor. An OS transistor has an extremely low off current. Therefore, by turning off the transistor MT1 that functions as a switch, the capacitance element C[N] can hold electric charge corresponding to the monitor voltage. That is, by turning off the transistors MT1 to MT4, the output voltage of the battery cell can be continuously applied to the input terminal of the comparator 113 connected to the node MN.

With the structure using the memory circuit including the OS transistor, the reference voltage can be held by utilizing extremely low off-state current, so that the reference voltage generation circuit can be activated intermittently. . Therefore, power consumption can be reduced.

FIG. 5B shows a structure in which a back gate electrode is provided in the transistor MT1 and a signal is applied to both the gate electrode and the back gate electrode in the structure shown in FIG. 5A. With the structure of FIG. 5B, a voltage for controlling the channel formation region can be applied from both the gate electrode and the back gate electrode. Therefore, the on/off control of the transistor MT1 functioning as a switch can be performed more reliably.

FIG. 5C shows a structure in which a back gate electrode is provided in the transistor MT1 in the structure shown in FIG. ing. As the structure of FIG. 5C, a structure in which a potential capable of controlling the threshold voltage is applied to the back gate potential line, so that off current can be reduced in a high-temperature environment. Therefore, the on/off control of the transistor MT1 functioning as a switch can be performed even in a high-temperature environment.

FIG. 6 is a timing chart for describing the operation of the memory circuit 114A illustrated in FIG. 5A. In the timing chart of FIG. 6, the signal S _m illustrated in FIGS. 4A and 5A, the potential of the node MN, the potential of the wiring providing the reference voltage Vref[N],
is shown for on or off.

From time T11 to time T12, the signal _Sm is set to H level to turn on the transistor MT1. A reference voltage is applied to one electrode of the capacitive element C[N], that is, the node MN. During this time, the switch PSW is turned on and the reference voltage Vref[N] is supplied to the memory circuit 114 .

From time T12 to time T13, the signal _Sm is set to L level to turn off the transistor MT1. A reference voltage is held at one electrode of the capacitive element C[N], that is, at the node MN.

From time T13 to time T14, the signal _Sm is set to L level to turn off the transistor MT1. The reference voltage continues to be held at one electrode of the capacitive element C[N], that is, at the node MN. During this time, the switch PSW is turned off and the reference voltage generation circuit 115 is put to rest.

The reference voltage is refreshed after a predetermined time elapses according to the sensor 117 . Time T14
From time T15, the switch PSW is turned on, and the reference voltage Vref to the storage circuit 114 is applied.
Resume supply of [N].

From time T15 to time T16, the signal _Sm is set to H level again to turn on the transistor MT1. The reference voltage is again applied to one electrode of the capacitive element C[N], that is, the node MN.

In the structure of one embodiment of the present invention, an OS transistor is used as a transistor for holding the reference voltage of the memory circuit 114 . Therefore, the charge corresponding to the reference voltage once written in the memory circuit 114 can be held for a long time.

(Embodiment 2)
In this embodiment, an operation example of the battery protection circuit described in the above embodiment and a power storage device including the battery protection circuit will be described.

FIG. 7 shows a flowchart for explaining an operation example of a battery protection circuit and a power storage device including the battery management circuit.

As described above, the battery protection circuit measures the current/voltage of each battery cell (step S00
1). Measurement of the current of each battery cell is performed by acquiring monitor current data, and measurement of the voltage of each battery cell is performed by acquiring monitor voltage data.

Next, the battery protection circuit determines whether or not the battery cells of the assembled battery are balanced (imbalance determination) by the arithmetic circuit of the battery protection circuit based on each data measured in step S001 (step S002). If there is no imbalance judgment, the process proceeds to step S005 for judgment of charging completion, and if charging is completed, the process ends. If charging is not completed, step S0 again
01.

Next, when the battery protection circuit determines that the battery is unbalanced in step S002, the arithmetic circuit generates a control signal (step S003).

Next, the battery protection circuit outputs a control signal to the cell balance circuit unit 130 to eliminate the unbalance of the battery cells, and activates the cell balance circuit unit 130 (step S004).
. The charge/discharge control transistor is a transistor provided in a wiring for transmitting voltage and current for charge/discharge.

By the operation described above, the battery protection circuit can charge the battery while detecting variations in the cell balance between the battery cells from the monitor voltage and the monitor current.

This embodiment can be appropriately combined with the description of other embodiments.

(Embodiment 3)
A configuration example of a semiconductor device that can be applied to the battery protection circuit described in the above embodiment will be described.

The semiconductor device illustrated in FIG. 8 includes a transistor 300, a transistor 500, a capacitor
00 and . 10A is a cross-sectional view of the transistor 500 in the channel length direction, FIG. 10B is a cross-sectional view of the transistor 500 in the channel width direction, and FIG.
) is a cross-sectional view of the transistor 300 in the channel width direction.

The transistor 500 is a transistor (OS transistor) including a metal oxide in a channel formation region. Since the transistor 500 has a low off-state current, written data can be retained for a long time by using the transistor 500 as an OS transistor included in the semiconductor device.

A semiconductor device described in this embodiment includes a transistor 300, a transistor 500, and a capacitor 600 as illustrated in FIG. The transistor 500 is provided above the transistor 300 , and the capacitor 600 is provided above the transistors 300 and 500 .

The transistor 300 is provided over a substrate 311 and has a conductor 316, an insulator 315, a semiconductor region 313 formed from part of the substrate 311, and low-resistance regions 314a and 314b functioning as source or drain regions. . Note that the transistor 300 can be applied to, for example, the transistor included in the comparator in any of the above embodiments.

In the transistor 300, as shown in FIG. 10C, a top surface and side surfaces in the channel width direction of a semiconductor region 313 are covered with a conductor 316 with an insulator 315 interposed therebetween. By making the transistor 300 Fin-type in this manner, the effective channel width is increased, so that the on-characteristics of the transistor 300 can be improved. Further, since the contribution of the electric field of the gate electrode can be increased, the off characteristics of the transistor 300 can be improved.

Note that the transistor 300 may be of either p-channel type or n-channel type.

A region in which a channel of the semiconductor region 313 is formed, a region in the vicinity thereof, the low-resistance regions 314a and 314b serving as a source region or a drain region, and the like preferably contain a semiconductor such as a silicon-based semiconductor. It preferably contains crystalline silicon. Alternatively, a material including Ge (germanium), SiGe (silicon germanium), GaAs (gallium arsenide), GaAlAs (gallium aluminum arsenide), or the like may be used.
A structure using silicon in which the effective mass is controlled by applying stress to the crystal lattice and changing the lattice spacing may be used. Alternatively, by using GaAs and GaAlAs, etc., the transistor 30
0 as HEMT (High Electron Mobility Transistor
).

In the low-resistance regions 314a and 314b, in addition to the semiconductor material applied to the semiconductor region 313, an element imparting n-type conductivity, such as arsenic or phosphorus, or an element imparting p-type conductivity, such as boron, is used. contains elements that

The conductor 316 functioning as a gate electrode is a semiconductor material such as silicon containing an element imparting n-type conductivity such as arsenic or phosphorus or an element imparting p-type conductivity such as boron, a metal material, or an alloy. material, or a conductive material such as a metal oxide material.

Note that 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, it is preferable to use a material such as titanium nitride or tantalum nitride for the conductor. Furthermore, in order to achieve both conductivity and embeddability, it is preferable to use a metal material such as tungsten or aluminum as a laminate for the conductor, and it is particularly preferable to use tungsten from the viewpoint of heat resistance.

Note that the transistor 300 illustrated in FIG. 8 is an example, and the structure thereof is not limited, and an appropriate transistor may be used depending on the circuit configuration and the driving method. For example, in the case where the semiconductor device includes only OS transistors, the transistor 300 may have a structure similar to that of the transistor 500 using an oxide semiconductor, as illustrated in FIG. Details of the transistor 500 will be described later.

An insulator 320 , an insulator 322 , an insulator 324 , and an insulator 326 are stacked in order to cover the transistor 300 .

As the insulator 320, the insulator 322, the insulator 324, and the insulator 326, for example, silicon oxide, silicon oxynitride, silicon nitride oxide, silicon nitride, aluminum oxide, aluminum oxynitride, aluminum nitride oxide, aluminum nitride, or the like is used. Just do it.

In this specification, silicon oxynitride refers to a material whose composition contains more oxygen than nitrogen, and silicon oxynitride refers to a material whose composition contains more nitrogen than oxygen. indicates In this specification, aluminum oxynitride refers to a material whose composition contains more oxygen than nitrogen, and aluminum oxynitride refers to a material whose composition contains more nitrogen than oxygen. indicates

The insulator 322 may function as a planarization film that planarizes a step caused by the transistor 300 or the like provided therebelow. For example, the top surface of insulator 322 is
It may be planarized by a planarization process using a chemical mechanical polishing (CMP) method or the like in order to improve planarity.

For the insulator 324, it is preferable to use a film having a barrier property such that hydrogen or impurities do not diffuse from the substrate 311, the transistor 300, or the like to the region where the transistor 500 is provided.

As an example of a film having a barrier property against hydrogen, silicon nitride formed by a CVD method can be used. Here, diffusion of hydrogen into a semiconductor element including an oxide semiconductor, such as the transistor 500, might degrade the characteristics of the semiconductor element. Therefore, it is preferable to use a film that suppresses diffusion of hydrogen between the transistor 500 and the transistor 300 . Specifically, the film that suppresses diffusion of hydrogen is a film from which the amount of desorption of hydrogen is small.

The desorption amount of hydrogen can be analyzed using, for example, thermal desorption spectroscopy (TDS). For example, the amount of hydrogen released from the insulator 324 is the amount of hydrogen atoms released per area of the insulator 324 when the surface temperature of the film is in the range of 50° C. to 500° C. in TDS analysis. 10×10 ¹⁵ atoms/cm ² or less, preferably 5×10 ¹⁵ a
Toms/cm ² or less is sufficient.

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

Capacitor elements 6
00 or a conductor 328 connected to the transistor 500, a conductor 330, and the like are buried. Note that the conductors 328 and 330 function as plugs or wirings. In addition, conductors that function as plugs or wiring may have a plurality of structures collectively given the same reference numerals. Further, in this specification and the like, the wiring and the plug connected to the wiring may be integrated. That is, part of the conductor may function as wiring, and part of the conductor may function as a plug.

As a material for each plug and wiring (conductor 328, conductor 330, etc.), a conductive material such as a metal material, an alloy material, a metal nitride material, or a metal oxide material is used as a single layer or a laminated layer. be able to. It is preferable to use a high-melting-point material such as tungsten or molybdenum that has both heat resistance and conductivity, and it is preferable to use tungsten. Alternatively, it is preferably made of a low resistance conductive material such as aluminum or copper. Wiring resistance can be reduced by using a low-resistance conductive material.

A wiring layer may be provided over the insulator 326 and the conductor 330 . For example, in FIG. 8, an insulator 350, an insulator 352, and an insulator 354 are stacked in this order. A conductor 356 is formed over the insulators 350 , 352 , and 354 . The conductor 356 functions as a plug or wiring connected to the transistor 300 . Note that the conductor 356 can be provided using a material similar to that of the conductors 328 and 330 .

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

Note that tantalum nitride or the like may be used as the conductor having a barrier property against hydrogen, for example. Further, by stacking tantalum nitride and tungsten having high conductivity, diffusion of hydrogen from the transistor 300 can be suppressed while the conductivity of the wiring is maintained. In this case, it is preferable that the tantalum nitride layer having a barrier property against hydrogen be in contact with the insulator 350 having a barrier property against hydrogen.

A wiring layer may be provided over the insulator 354 and the conductor 356 . For example, in FIG. 8, an insulator 360, an insulator 362, and an insulator 364 are stacked in order. A conductor 366 is formed over the insulators 360 , 362 , and 364 . The conductor 366 functions as a plug or wiring. Note that the conductor 366 can be provided using a material similar to that of the conductors 328 and 330 .

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

A wiring layer may be provided over the insulator 364 and the conductor 366 . For example, in FIG. 8, an insulator 370, an insulator 372, and an insulator 374 are stacked in this order. A conductor 376 is formed over the insulators 370 , 372 , and 374 . The conductor 376 functions as a plug or wiring. Note that the conductor 376 can be provided using a material similar to that of the conductors 328 and 330 .

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

A wiring layer may be provided over the insulator 374 and the conductor 376 . For example, in FIG. 8, an insulator 380, an insulator 382, and an insulator 384 are stacked in order. A conductor 386 is formed over the insulators 380 , 382 , and 384 . The conductor 386 functions as a plug or wiring. Note that the conductor 386 can be provided using a material similar to that of the conductors 328 and 330 .

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

In the above, the wiring layer including the conductor 356, the wiring layer including the conductor 366, and the conductor 376
Although the wiring layer including the conductor 386 and the wiring layer including the conductor 386 have been described, the semiconductor device according to this embodiment is not limited to this. The number of wiring layers similar to the wiring layer including the conductor 356 may be three or less, or the number of wiring layers similar to the wiring layer including the conductor 356 may be five or more.

An insulator 510 , an insulator 512 , an insulator 514 , and an insulator 516 are stacked in this order over the insulator 384 . Any of the insulator 510, the insulator 512, the insulator 514, and the insulator 516 is preferably a substance having barrier properties against oxygen and hydrogen.

For the insulators 510 and 514, for example, a film having barrier properties such that hydrogen or impurities do not diffuse from the substrate 311 or a region where the transistor 300 is provided to a region where the transistor 500 is provided is used. is preferred. Therefore, insulator 324
can be used.

As an example of a film having a barrier property against hydrogen, silicon nitride formed by a CVD method can be used. Here, diffusion of hydrogen into a semiconductor element including an oxide semiconductor, such as the transistor 500, might degrade the characteristics of the semiconductor element. Therefore, it is preferable to use a film that suppresses diffusion of hydrogen between the transistor 500 and the transistor 300 . Specifically, the film that suppresses the diffusion of hydrogen is a film from which the amount of desorption of hydrogen is small.

Further, as the film having a barrier property against hydrogen, for example, the insulator 510 and the insulator 5 can be used.
14 is preferably a metal oxide such as aluminum oxide, hafnium oxide, or tantalum oxide.

In particular, aluminum oxide has a high shielding effect of preventing the penetration of both oxygen and impurities such as hydrogen and moisture, which cause variations in the electrical characteristics of the transistor. Therefore, aluminum oxide can prevent impurities such as hydrogen and moisture from entering the transistor 500 during and after the manufacturing process of the transistor. Moreover, the transistor 500
It is possible to suppress the release of oxygen from the oxide that constitutes the Therefore, transistor 5
00 as a protective film.

Further, for example, the insulators 512 and 516 can be formed using a material similar to that of the insulator 320 . In addition, by using a material with a relatively low dielectric constant for these insulators, parasitic capacitance generated between wirings can be reduced. For example, the insulators 512 and 516 can be formed using a silicon oxide film, a silicon oxynitride film, or the like.

In addition, the insulator 510 , the insulator 512 , the insulator 514 , and the insulator 516 include the conductor 5
18, a conductor (for example, the conductor 503) constituting the transistor 500, and the like are buried. Note that the conductor 518 functions as a plug or wiring that is connected to the capacitor 600 or the transistor 300 . Conductor 518 includes conductor 328 and conductor 3
It can be provided using the same material as 30 .

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

A transistor 500 is provided above the insulator 516 .

As shown in FIGS. 10A and 10B, the transistor 500 includes insulators 514 and 5
16, an insulator 520 disposed over the insulator 516 and the conductor 503, an insulator 522 disposed over the insulator 520, and the insulator 522; Overlying insulator 524 and oxide 530a overlying insulator 524
, an oxide 530b placed over the oxide 530a, conductors 542a and 542b spaced apart from each other over the oxide 530b, and conductors 542a and 542b.
An insulator 580 is provided above and an opening is formed so as to overlap with the conductor 542a and the conductor 542b, an oxide 530c is provided on the bottom and side surfaces of the opening, and the oxide 530c is provided on the surface where the oxide 530c is formed. and a conductor 560 provided on the surface where the insulator 550 is formed.

In addition, as shown in FIGS. 10A and 10B, an oxide 530a, an oxide 530b, and a conductor 5
42a and conductor 542b, and insulator 544 is preferably disposed between insulator 580. FIG. 10A and 10B, the conductor 560 includes a conductor 560a provided inside the insulator 550 and a conductor 560b embedded inside the conductor 560a. and preferably. Further, an insulator 574 is preferably provided over the insulator 580, the conductor 560, and the insulator 550 as shown in FIGS.

Note that the oxide 530a, the oxide 530b, and the oxide 530c are collectively referred to as the oxide 530 in some cases below.

Note that although the transistor 500 has a structure in which three layers of the oxide 530a, the oxide 530b, and the oxide 530c are stacked in a region where a channel is formed and in the vicinity thereof, the present invention is limited to this. not a thing 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,
Alternatively, a configuration may be adopted in which a laminated structure of four or more layers is provided. Although the conductor 560 has a two-layer structure in the transistor 500, the present invention is not limited to this. For example, the conductor 560 may have a single-layer structure or a laminated structure of three or more layers. Further, the transistor 500 illustrated in FIGS. 8 and 10A is only an example, and the structure is not limited, and an appropriate transistor may be used depending on the circuit structure and driving method.

Here, the conductor 560 functions as a gate electrode of the transistor, and the conductors 542a and 542b function as source and drain electrodes, respectively. As described above, the conductor 560 is formed to be embedded in the opening of the insulator 580 and the region sandwiched between the conductors 542a and 542b. Conductor 560, Conductor 542a and Conductor 5
The placement of 42b is chosen to be self-aligned with respect to the insulator 580 opening. That is, in the transistor 500, the gate electrode can be arranged between the source electrode and the drain electrode in a self-aligned manner. Therefore, the conductor 560 can be formed without providing an alignment margin, so that the area occupied by the transistor 500 can be reduced. As a result, miniaturization and high integration of the semiconductor device can be achieved.

Furthermore, since conductor 560 is formed in a region between conductors 542a and 542b in a self-aligned manner, conductor 560 does not have a region that overlaps conductors 542a or 542b. Accordingly, parasitic capacitance formed between the conductor 560 and the conductors 542a and 542b can be reduced. Therefore, the switching speed of the transistor 500 can be improved and high frequency characteristics can be obtained.

Conductor 560 may function as a first gate (also called top gate) electrode. In some cases, the conductor 503 functions as a second gate (also referred to as a bottom gate) electrode. In that case, the threshold voltage of the transistor 500 can be controlled by changing the potential applied to the conductor 503 independently of the potential applied to the conductor 560 . In particular, by applying a negative potential to conductor 503, transistor 5
00 threshold voltage can be made higher than 0 V, and the off current can be reduced. Therefore, applying a negative potential to the conductor 503 is more effective than not applying a negative potential to the conductor 560 .
The drain current can be reduced when the potential applied to is 0V.

The conductor 503 is arranged so as to overlap with the oxide 530 and the conductor 560 . Accordingly, when a potential is applied to the conductor 560 and the conductor 503, the electric field generated from the conductor 560 and the electric field generated from the conductor 503 are connected to each other, so that the channel formation region formed in the oxide 530 is covered. can be done. In this specification and the like, a transistor structure in which a channel formation region is electrically surrounded by electric fields of a first gate electrode and a second gate electrode is
It is called a surrounded channel (S-channel) structure.

In addition, the conductor 503 has a structure similar to that of the conductor 518, and the insulators 514 and 5
A conductor 503a is formed in contact with the inner wall of the opening 16, and a conductor 503b is further formed inside. Note that although the structure in which the conductors 503a and 503b are stacked is shown in the transistor 500, the present invention is not limited to this. For example, the conductor 503 may be provided as a single layer or a laminated structure of three or more layers.

Here, for the conductor 503a, it is preferable to use a conductive material that has a function of suppressing diffusion of impurities such as hydrogen atoms, hydrogen molecules, water molecules, and copper atoms (the impurities are less likely to permeate). Alternatively, it is preferable to use a conductive material that has a function of suppressing diffusion of oxygen (eg, at least one of oxygen atoms, oxygen molecules, etc.) (the above oxygen is difficult to permeate). note that,
In this specification, the function of suppressing the diffusion of impurities or oxygen is the function of suppressing the diffusion of one or all of the impurities or oxygen.

For example, since the conductor 503a has a function of suppressing the diffusion of oxygen, the conductor 503a
It is possible to suppress the decrease in conductivity due to oxidation of b.

In the case where the conductor 503 also functions as a wiring, the conductor 503b is preferably made of a highly conductive material containing tungsten, copper, or aluminum as its main component.
In that case, the conductor 505 is not necessarily provided. Note that although the conductor 503b is illustrated as a single layer, it may have a layered structure, for example, a layered layer of titanium, titanium nitride, and any of the above conductive materials.

The insulator 520, the insulator 522, the insulator 524, and the insulator 550 function as a second gate insulating film.

Here, the insulator 524 in contact with the oxide 530 preferably contains more oxygen than the stoichiometric composition. In other words, the insulator 524 preferably has an excess oxygen region. By providing such an insulator containing excess oxygen in contact with the oxide 530, oxygen vacancies in the oxide 530 can be reduced and the reliability of the transistor 500 can be improved.

Specifically, an oxide material from which part of oxygen is released by heating is preferably used as the insulator having the excess oxygen region. The oxide that desorbs oxygen by heating is TDS (Th
(Ermal Desorption Spectroscopy) analysis shows that the amount of oxygen released in terms of oxygen atoms is 1.0×10 ¹⁸ atoms/cm ³ or more, preferably 1.0.
×10 ¹⁹ atoms/cm ³ or more, more preferably 2.0 × 10 ¹⁹ atoms/c
m ³ , or an oxide film having a density of 3.0×10 ²⁰ atoms/cm ³ or more. The surface temperature of the film during the TDS analysis is preferably in the range of 100° C. or higher and 700° C. or lower, or 100° C. or higher and 400° C. or lower.

Also, when the insulator 524 has an excess oxygen region, the insulator 522 may contain oxygen (eg,
It preferably has a function of suppressing the diffusion of oxygen atoms, oxygen molecules, etc. (it is difficult for the oxygen to permeate).

Since the insulator 522 has a function of suppressing diffusion of oxygen and impurities, oxygen contained in the oxide 530 does not diffuse toward the insulator 520, which is preferable. In addition, the conductor 503 can be prevented from reacting with oxygen contained in the insulator 524 and the oxide 530 .

The insulator 522 is, for example, aluminum oxide, hafnium oxide, an oxide containing aluminum and hafnium (hafnium aluminate), tantalum oxide, zirconium oxide, lead zirconate titanate (PZT), strontium titanate (SrTiO3) _, or (Ba
, Sr)TiO ₃ (BST) or other so-called high-k materials are preferably used in a single layer or a stack of insulators. As transistors are miniaturized and highly integrated, thinning of gate insulating films may cause problems such as leakage current. By using a high-k material for the insulator that functions as the gate insulating film, it is possible to reduce the gate potential during transistor operation while maintaining the physical film thickness.

In particular, an insulator containing an oxide of one or both of aluminum and hafnium, which is an insulating material having a function of suppressing diffusion of impurities and oxygen (through which oxygen is difficult to permeate), is preferably used. As the insulator containing oxides of one or both of aluminum and hafnium, aluminum oxide, hafnium oxide, an oxide containing aluminum and hafnium (hafnium aluminate), or the like is preferably used. When the insulator 522 is formed using such a material, the insulator 522 prevents oxygen from being released from the oxide 530 and
It functions as a layer that suppresses entry of impurities such as hydrogen into the oxide 530 from the periphery of the .

Alternatively, aluminum oxide, bismuth oxide, germanium oxide, niobium oxide, silicon oxide, titanium oxide, tungsten oxide, yttrium oxide, or zirconium oxide may be added to these insulators. Alternatively, these insulators may be nitrided. Silicon oxide, silicon oxynitride, or silicon nitride may be stacked over the above insulator.

Insulator 520 is also preferably thermally stable. For example, silicon oxide and silicon oxynitride are preferred because they are thermally stable. Further, by combining an insulator made of a high-k material with silicon oxide or silicon oxynitride, the insulators 520 and 526 having a stacked structure which are thermally stable and have a high relative dielectric constant can be obtained.

Note that in the transistor 500 in FIGS. 10A and 10B, the insulator 520, the insulator 522, and the insulator 524 are illustrated as the second gate insulating film having a stacked-layer structure of three layers. The second gate insulating film may have a single layer, two layers, or a laminated structure of four or more layers.
In that case, it is not limited to a laminated structure made of the same material, and a laminated structure made of different materials may be used.

In the transistor 500, a metal oxide functioning as an oxide semiconductor is preferably used for the oxide 530 including a channel formation region. For example, as oxide 530, In-M-
Zn oxide (element M is aluminum, gallium, yttrium, copper, vanadium, beryllium, boron, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, magnesium, etc. It is preferable to use metal oxides such as selected one or more. In particular, the oxide 53
In-M-Zn oxides that can be applied as 0 include CAAC-OS described in Embodiment 4,
CAC-OS is preferred. Further, as the oxide 530, In—Ga oxide, I
n-Zn oxide may also be used.

A metal oxide that functions as a channel formation region in the oxide 530 preferably has a bandgap of 2 eV or more, preferably 2.5 eV or more. By using a metal oxide with a large bandgap in this manner, off-state current of a transistor can be reduced.

Oxide 530 has oxide 530a under oxide 530b so that oxide 530a
Impurities can be prevented from diffusing into the oxide 530b from the structure formed below. In addition, by providing the oxide 530c over the oxide 530b, diffusion of impurities from a structure formed above the oxide 530c to the oxide 530b can be suppressed.

Note that the oxide 530 preferably has a layered structure with oxides having different atomic ratios of metal atoms. Specifically, in the metal oxide used for the oxide 530a, the atomic number ratio of the element M among the constituent elements is greater than the atomic number ratio of the element M among the constituent elements in the metal oxide used for the oxide 530b. is preferred. Further, in the metal oxide used for the oxide 530a, the atomic ratio of the element M to In is preferably higher than the atomic ratio of the element M to In in the metal oxide used for the oxide 530b. In addition, the atomic ratio of In to the element M in the metal oxide used for the oxide 530b is preferably higher than the atomic ratio of In to the element M in the metal oxide used for the oxide 530a. again,
Oxide 530c can be a metal oxide that can be used for oxide 530a or oxide 530b.

In addition, the energies of the conduction band bottoms of the oxides 530a and 530c are
It is preferably higher than the energy of the conduction band bottom of b. In other words, the electron affinities of the oxides 530a and 530c are preferably smaller than that of the oxide 530b.

Here, the energy level at the bottom of the conduction band changes smoothly at the junction of the oxide 530a, the oxide 530b, and the oxide 530c. In other words, it can be said that the energy level of the bottom of the conduction band at the junction of the oxide 530a, the oxide 530b, and the oxide 530c continuously changes or continuously joins. To do this, the oxide 530
The defect level density of the mixed layers formed at the interface between a and the oxide 530b and the interface between the oxide 530b and the oxide 530c should be reduced.

Specifically, the oxides 530a and 530b, and the oxides 530b and 530c are
A mixed layer with a low defect level density can be formed by having a common element (as a main component) other than oxygen. For example, when the oxide 530b is an In--Ga--Zn oxide, the oxides 530a and 530c may be In--Ga--Zn oxide, Ga--Zn oxide, gallium oxide, or the like.

At this time, the main path of carriers is the oxide 530b. oxide 530a, oxide 5
By using the structure 30c as described above, the defect level density at the interface between the oxide 530a and the oxide 530b and the interface between the oxide 530b and the oxide 530c can be reduced. Therefore, the influence of interface scattering on carrier conduction is reduced, and the transistor 500 can obtain a high on-state current.

A conductor 542a functioning as a source electrode and a drain electrode is formed over the oxide 530b.
, and a conductor 542b are provided. Conductors 542a and 542b include aluminum, chromium, copper, silver, gold, platinum, tantalum, nickel, titanium, molybdenum, tungsten, hafnium, vanadium, niobium, manganese, magnesium, zirconium, beryllium, indium, and ruthenium. , iridium, strontium, and lanthanum, an alloy containing the above-described metal elements as a component, or an alloy in which the above-described metal elements are combined. For example, tantalum nitride, titanium nitride, tungsten, nitride containing titanium and aluminum, nitride containing tantalum and aluminum, ruthenium oxide, ruthenium nitride, oxide containing strontium and ruthenium, oxide containing lanthanum and nickel, and the like are used. is preferred. Also, 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 difficult to oxidize. It is preferable because it is a conductive material or a material that maintains conductivity even after absorbing oxygen. Furthermore, a metal nitride film such as tantalum nitride is preferable because it has a barrier property against hydrogen or oxygen.

Further, although FIG. 10 shows the conductor 542a and the conductor 542b as single-layer structures,
A laminated structure of two or more layers may also be used. For example, a tantalum nitride film and a tungsten film are preferably stacked. Alternatively, a titanium film and an aluminum film may be stacked. A two-layer structure in which an aluminum film is stacked over a tungsten film, a two-layer structure in which a copper film is stacked over a copper-magnesium-aluminum alloy film, a two-layer structure in which a copper film is stacked over a titanium film, a two-layer structure in which a copper film is stacked over a titanium film, A two-layer structure in which copper films are stacked may be used.

Further, a three-layer structure in which a titanium film or a titanium nitride film is laminated, an aluminum film or a copper film is laminated on the titanium film or the titanium nitride film, and a titanium film or a titanium nitride film is formed thereon, a molybdenum film or a There is a three-layer structure including a molybdenum nitride film, an aluminum film or a copper film laminated on the molybdenum film or the molybdenum nitride film, and a molybdenum film or a molybdenum nitride film formed thereon. Note that a transparent conductive material containing indium oxide, tin oxide, or zinc oxide may be used.

Further, as shown in FIG. 10A, a conductor 542a (a conductor 542b) of the oxide 530
) and its vicinity, regions 543a and 543b may be formed as low-resistance regions. At this time, the region 543a functions as one of the source region and the drain region, and the region 543b functions as the other of the source region and the drain region. A channel formation region is formed in a region sandwiched between the regions 543a and 543b.

By providing the conductor 542a (the conductor 542b) so as to be in contact with the oxide 530,
The oxygen concentration in the region 543a (region 543b) may decrease. Also, the area 543a (
A metal compound layer containing the metal contained in the conductor 542a (the conductor 542b) and the component of the oxide 530 may be formed in the region 543b). In such a case, the carrier density of the region 543a (region 543b) increases, and the region 543a (region 543b) becomes a low resistance region.

The insulator 544 is provided so as to cover the conductors 542a and 542b and suppress oxidation of the conductors 542a and 542b. At this time, the insulator 544 is the oxide 5
30 and may be provided so as to be in contact with the insulator 524 .

The insulator 544 is a metal oxide containing one or more selected from hafnium, aluminum, gallium, yttrium, zirconium, tungsten, titanium, tantalum, nickel, germanium, neodymium, lanthanum, magnesium, and the like. can be used. Alternatively, silicon nitride oxide, silicon nitride, or the like can be used as the insulator 544 .

In particular, as the insulator 544, an insulator containing one or both oxides of aluminum and hafnium, such as aluminum oxide, hafnium oxide, or an oxide containing aluminum and hafnium (hafnium aluminate), is preferably used. . In particular, hafnium aluminate has higher heat resistance than hafnium oxide film. Therefore, it is preferable because it is difficult to crystallize in the heat history in the subsequent steps. Note that the conductor 542a and the conductor 542
The insulator 544 is not an essential component if b is a material having oxidation resistance or if the conductivity does not significantly decrease even if oxygen is absorbed. It may be appropriately designed depending on the required transistor characteristics.

The insulator 544 can suppress diffusion of impurities such as water and hydrogen contained in the insulator 580 through the oxide 530c and the insulator 550 into the oxide 530b. In addition, oxidation of the conductor 560 due to excess oxygen in the insulator 580 can be suppressed.

The insulator 550 functions as a first gate insulating film. Insulator 550 is oxide 530
It is preferable to dispose in contact with the inner side (upper surface and side surface) of c. The insulator 550 is preferably formed using an insulator that contains excess oxygen and releases oxygen by heating, similarly to the insulator 524 described above.

Specifically, silicon oxide with excess oxygen, silicon oxynitride, silicon oxynitride,
Silicon nitride, silicon oxide to which fluorine is added, silicon oxide to which carbon is added, silicon oxide to which carbon and nitrogen are added, and silicon oxide having vacancies can be used. In particular, silicon oxide and silicon oxynitride are preferable because they are stable against heat.

An insulator from which oxygen is released by heating is provided as the insulator 550 in contact with the top surface of the oxide 530c.
can effectively supply oxygen to the channel formation region of Further, similarly to the insulator 524, the concentration of impurities such as water or hydrogen in the insulator 550 is preferably reduced. The thickness of the insulator 550 is preferably 1 nm or more and 20 nm or less.

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

Note that the insulator 550 may have a stacked structure similarly to the second gate insulating film. As transistors are miniaturized and highly integrated, thinning of the gate insulating film may cause problems such as leakage current. By forming a laminated structure with a material that is relatively stable, it is possible to reduce the gate potential during transistor operation while maintaining the physical film thickness. Moreover, it is possible to obtain a laminated structure that is thermally stable and has a high dielectric constant.

Although the conductor 560 functioning as the first gate electrode has a two-layer structure in FIGS. 10A and 10B, it may have a single-layer structure or a stacked structure of three or more layers.

The conductor 560a has a function of suppressing diffusion of impurities such as hydrogen atoms, hydrogen molecules, water molecules, nitrogen atoms, nitrogen molecules, nitrogen oxide molecules (such as N ₂ O, NO, NO ₂ ), and copper atoms. Materials are preferably used. Alternatively, a conductive material having a function of suppressing diffusion of oxygen (eg, at least one of oxygen atoms and oxygen molecules) is preferably used. conductor 56
Since 0a has a function of suppressing diffusion of oxygen, oxygen contained in the insulator 550 can suppress oxidation of the conductor 560b and a decrease in conductivity. As the conductive material having a function of suppressing diffusion of oxygen, tantalum, tantalum nitride, ruthenium, ruthenium oxide, or the like is preferably used, for example. Also, as the conductor 560a,
An oxide semiconductor that can be applied to the oxide 530 can be used. In that case, conductor 560
By depositing b by a sputtering method, the electrical resistance of the conductor 560a can be lowered to make it a conductor. This can be called an OC (Oxide Conductor) electrode.

A conductive material containing tungsten, copper, or aluminum as its main component is preferably used for the conductor 560b. In addition, since the conductor 560b also functions as a wiring, a conductor with high conductivity is preferably used. For example, a conductive material whose main component is tungsten, copper, or aluminum can be used. Further, the conductor 560b may have a layered structure, for example, a layered structure of titanium, titanium nitride, and the above conductive material.

The insulator 580 is provided over the conductors 542a and 542b with the insulator 544 interposed therebetween. Insulator 580 preferably has excess oxygen regions. For example, insulator 58
0, silicon oxide, silicon oxynitride, silicon nitride oxide, silicon nitride, silicon oxide to which fluorine is added, silicon oxide to which carbon is added, silicon oxide to which carbon and nitrogen are added, silicon oxide having vacancies, or resin etc. is preferable. In particular, silicon oxide and silicon oxynitride are preferable because they are thermally stable. In particular, silicon oxide and silicon oxide having vacancies are preferable because an excess oxygen region can be easily formed in a later step.

Insulator 580 preferably has excess oxygen regions. By providing the insulator 580 from which oxygen is released by heating in contact with the oxide 530c, oxygen in the insulator 580 can be efficiently supplied to the oxide 530 through the oxide 530c. Note that the insulator 5
Preferably, the concentration of impurities such as water or hydrogen in 80 is reduced.

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

When miniaturizing a semiconductor device, it is required to shorten the gate length.
The conductivity of 60 should not be compromised. Therefore, when the film thickness of the conductor 560 is increased, the conductor 560 can have a shape with a high aspect ratio. In this embodiment mode, since the conductor 560 is embedded in the opening of the insulator 580, the conductor 560 can be formed without collapsing during the process even if the conductor 560 has a high aspect ratio. can be done.

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

For example, the insulator 574 may be hafnium, aluminum, gallium, yttrium,
A metal oxide containing one or more selected from zirconium, tungsten, titanium, tantalum, nickel, germanium, magnesium, or the like can be used.

In particular, aluminum oxide has a high barrier property and can suppress diffusion of hydrogen and nitrogen even in a thin film having a thickness of 0.5 nm or more and 3.0 nm or less. Therefore, the aluminum oxide film formed by the sputtering method can function not only as an oxygen supply source but also as a barrier film against impurities such as hydrogen.

An insulator 581 functioning as an interlayer film is preferably provided over the insulator 574 . The insulator 581 preferably has a reduced concentration of impurities such as water or hydrogen in the film, similarly to the insulator 524 and the like.

In addition, conductors 540 a and 540 b are provided in openings formed in the insulators 581 , 574 , 580 , and 544 . Conductor 540a and conductor 54
0b are provided facing each other with the conductor 560 interposed therebetween. Conductor 540a and conductor 540b are
It has the same structure as a conductor 546 and a conductor 548 which will be described later.

An insulator 582 is provided over the insulator 581 . It is preferable that the insulator 582 use a substance that has a barrier property against oxygen and hydrogen. Therefore, a material similar to that of the insulator 514 can be used for the insulator 582 . For example, the insulator 582 is preferably formed using a metal oxide such as aluminum oxide, hafnium oxide, or tantalum oxide.

In particular, aluminum oxide has a high shielding effect of preventing the penetration of both oxygen and impurities such as hydrogen and moisture, which cause variations in the electrical characteristics of the transistor. Therefore, aluminum oxide can prevent impurities such as hydrogen and moisture from entering the transistor 500 during and after the manufacturing process of the transistor. Moreover, the transistor 500
It is possible to suppress the release of oxygen from the oxide that constitutes the Therefore, transistor 5
00 as a protective film.

An insulator 586 is provided over the insulator 582 . A material similar to that of the insulator 320 can be used for the insulator 586 . In addition, by using a material with a relatively low dielectric constant for these insulators, parasitic capacitance generated between wirings can be reduced. For example, a silicon oxide film, a silicon oxynitride film, or the like can be used as the insulator 586 .

In addition, the insulator 520, the insulator 522, the insulator 524, the insulator 544, the insulator 580, the insulator 574, the insulator 581, the insulator 582, and the insulator 586 include the conductor 546, the conductor 548, and the like. is embedded.

The conductors 546 and 548 function as plugs or wirings that connect to the capacitor 600 , the transistor 500 , or the transistor 300 . The conductors 546 and 548 can be formed using a material similar to that of the conductors 328 and 330 .

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

A conductor 612 may be provided over the conductor 546 and the conductor 548 . conductor 6
12 functions as a plug or wiring connected to the transistor 500 . The conductor 610 functions as an electrode of the capacitor 600 . Note that the conductor 612 and the conductor 610 can be formed at the same time.

For the conductors 612 and 610, metal films containing an element selected from molybdenum, titanium, tantalum, tungsten, aluminum, copper, chromium, neodymium, and scandium;
Alternatively, a metal nitride film (a tantalum nitride film, a titanium nitride film, a molybdenum nitride film, a tungsten nitride film) containing the above elements as components, or the like can be used. or 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, indium tin oxide containing silicon oxide, etc. Conductive materials can also be applied.

Although the conductors 612 and 610 each have a single-layer structure in FIGS. 8A and 8B, they are not limited to this structure and may have a stacked structure of two or more layers. For example, between a conductor with barrier properties and a conductor with high conductivity, a conductor with barrier properties and a conductor with high adhesion to the conductor with high conductivity may be formed.

A conductor 620 is provided so as to overlap with the conductor 610 with an insulator 630 interposed therebetween. Note that a conductive material such as a metal material, an alloy material, or a metal oxide material can be used for the conductor 620 . It is preferable to use a high-melting-point material such as tungsten or molybdenum that has both heat resistance and conductivity, and it is particularly preferable to use tungsten. In addition, when forming simultaneously with another structure such as a conductor, a low-resistance metal material such as Cu (copper) or Al (aluminum) may be used.

An insulator 640 is provided over the conductor 620 and the insulator 630 . insulator 64
0 can be provided using a material similar to that of insulator 320 . Also, the insulator 640
It may function as a planarizing film covering the uneven shape thereunder.

With the use of this structure, variation in electrical characteristics can be suppressed and reliability can be improved in a semiconductor device including a transistor including an oxide semiconductor. Alternatively, miniaturization or high integration can be achieved in a battery protection circuit using a transistor including an oxide semiconductor.

This embodiment can be appropriately combined with the description of other embodiments.

(Embodiment 4)
In this embodiment, an example in which the battery protection circuit described in the above embodiment is an electronic component will be described with reference to FIG.

FIG. 11A illustrates an example in which the battery control circuit described in the above embodiment is an electronic component. The electronic component is also called a semiconductor package or an IC package. This electronic component has a plurality of standards and names depending on the direction of terminal extraction and the shape of the terminal. Therefore, in the present embodiment, an example thereof will be described.

The circuit part composed of OS transistors and Si transistors is an assembly process (post-process)
After that, it is completed by combining multiple detachable parts on the printed circuit board.

The post-process can be completed through each process shown in FIG.
Specifically, after the element substrate obtained in the preceding process is completed (step S1), the back surface of the substrate is ground (step S2). By thinning the substrate at this stage, it is possible to reduce the warpage of the substrate in the previous process and to reduce the size of the component.

A dicing process is performed in which the back surface of the substrate is ground and the substrate is separated into a plurality of chips. Then, a die bonding process is performed in which the separated chips are individually picked up, mounted on a lead frame, and bonded (step S3). For the bonding between the chip and the lead frame in this die bonding process, a suitable method such as resin bonding or tape bonding is selected according to the product. In addition, the die bonding process may be carried out by mounting on an interposer and bonding.

Next, wire bonding is performed to electrically connect the leads of the lead frame and the electrodes on the chip with thin metal wires (step S4). A silver wire or a gold wire can be used for the thin metal wire. Ball bonding or wedge bonding can be used for wire bonding.

The wire-bonded chip is subjected to a molding process in which it is sealed with epoxy resin or the like (step S5). By performing the molding process, the inside of the electronic component is filled with resin, making it possible to reduce damage to the built-in circuits and wires due to mechanical external force, and to reduce deterioration of characteristics due to moisture and dust. can.

The leads of the lead frame are then plated. Then, the leads are cut and formed (step S6). This plating treatment prevents the leads from rusting, so that soldering can be performed more reliably when they are later mounted on a printed circuit board.

Next, printing processing (marking) is applied to the surface of the package (step S7). Then, through a final inspection process (step S8), an electronic component having a circuit section including a PLD is completed (step S9).

A schematic perspective view of the completed electronic component is shown in FIG. FIG. 11B shows a schematic perspective view of a QFP (Quad Flat Package) as an example of an electronic component. An electronic component 700 illustrated in FIG. 11B includes leads 701 and a circuit portion 703 . An electronic component 700 shown in FIG. 11B is mounted on a printed circuit board 702, for example.
A plurality of such electronic components 700 are combined and electrically connected to each other on a printed circuit board 702 so that they can be mounted inside an electrical device. Completed circuit board 70
4 is provided inside the electrical equipment or the like.

(Embodiment 5)
In this embodiment, configurations of a power storage device and a power storage system to which the electronic component including the battery protection circuit described in the above embodiment can be applied will be described.

[Cylindrical secondary battery]
An example of a cylindrical secondary battery is described with reference to FIG. Cylindrical secondary battery 4
00, as shown in FIG. 12A, has a positive electrode cap (battery lid) 401 on the top surface and battery cans (armor cans) 402 on the side and bottom surfaces. These positive electrode cap 401 and the battery can (
It is insulated from the exterior can 402 by a gasket (insulation packing) 410 .

FIG. 12B shows an example of the power storage system 415. FIG. A power storage system 415 includes a plurality of secondary batteries 400 . The positive electrode of each secondary battery is a conductor 42 separated by an insulator 425.
4 and are electrically connected. The conductor 424 is connected to the control circuit 4 via the wiring 423 .
20 is electrically connected. A negative electrode of each secondary battery is electrically connected to the control circuit 420 through a wiring 426 . As the control circuit 420, the battery protection circuit described in the previous embodiment can be used.

FIG. 12C illustrates an example of the power storage system 415. FIG. A power storage system 415 includes a plurality of secondary batteries 400 , which are sandwiched between conductive plates 413 and 414 . The plurality of secondary batteries 400 are electrically connected to the conductive plates 413 and 414 by wirings 416 . The plurality of secondary batteries 400 may be connected in parallel, may be connected in series, or may be connected in series after being connected in parallel. By configuring the power storage system 415 including the plurality of secondary batteries 400, a large amount of power can be extracted.

A temperature control device may be provided between the plurality of secondary batteries 400 . When the secondary battery 400 is overheated, it can be cooled by the temperature control device, and when the secondary battery 400 is too cold, it can be heated by the temperature control device. Therefore, the performance of power storage system 415 is less likely to be affected by the outside air temperature.

In addition, in FIG. 12C, the power storage system 415 is electrically connected to the control circuit 420 through wirings 421 and 422 . As the control circuit 420, the battery protection circuit described in the previous embodiment can be used. The wiring 421 is electrically connected to the positive electrodes of the plurality of secondary batteries 400 through the conductive plate 413 , and the wiring 422 is electrically connected to the negative electrodes of the plurality of secondary batteries 400 through the conductive plate 414 .

[Secondary battery pack]
Next, an example of a power storage system of one embodiment of the present invention will be described with reference to FIGS.

FIG. 13A is a diagram showing the appearance of the secondary battery pack 531. FIG. FIG. 13B is a diagram illustrating the configuration of the secondary battery pack 531. FIG. The secondary battery pack 531 has a circuit board 501 and secondary batteries 513 . A label 509 is attached to the secondary battery 513 . Circuit board 501 is fixed by seal 515 . Moreover, the secondary battery pack 531
It has an antenna 517 .

The circuit board 501 has a control circuit 590 . The battery protection circuit described in the above embodiment can be used for the control circuit 590 . For example, as shown in FIG. 13B, a circuit board 50
1 has a control circuit 590 . Also, the circuit board 501 is electrically connected to the terminal 511 . The circuit board 501 is also electrically connected to the antenna 517 , one of the positive and negative leads 551 and the other of the positive and negative leads 552 of the secondary battery 513 .

Alternatively, as shown in FIG. 13C, the circuit system 5 provided on the circuit board 501
90a and a circuit system 590 electrically connected to circuit board 501 via terminals 511.
and b. For example, a portion of the control circuitry of one aspect of the present invention may be circuit system 59
0a and another portion in circuit system 590b, respectively.

Note that the antenna 517 is not limited to a coil shape, and may have a linear shape or a plate shape, for example. Further, antennas such as planar antennas, aperture antennas, traveling wave antennas, EH antennas, magnetic field antennas, and dielectric antennas may be used. Alternatively, antenna 914 may be a planar conductor. This flat conductor can function as one of conductors for electric field coupling. In other words, the antenna 914 may function as one of the two conductors of the capacitor. As a result, electric power can be exchanged not only by electromagnetic fields and magnetic fields, but also by electric fields.

Secondary battery pack 531 has layer 519 between antenna 517 and secondary battery 513 . The layer 519 has a function of shielding an electromagnetic field generated by the secondary battery 513, for example. A magnetic material, for example, can be used as the layer 519 .

The secondary battery 513 has a wound battery element 593 as shown in FIG. 13C. The battery element 593 has a negative electrode 594 , a positive electrode 595 and a separator 596 . A battery element 593 is obtained by laminating a negative electrode 594 and a positive electrode 595 with a separator 596 interposed therebetween, and winding the laminated sheet.

This embodiment can be appropriately combined with the description of other embodiments.

(Embodiment 6)
In this embodiment, an example in which a vehicle is equipped with a power storage system that is one embodiment of the present invention will be described. Vehicles include, for example, automobiles, two-wheeled vehicles, and bicycles.

When a power storage system is installed in a vehicle, hybrid vehicles (HEV), electric vehicles (EV),
Alternatively, next-generation clean energy vehicles such as plug-in hybrid vehicles (PHEV) can be realized.

FIG. 14 illustrates a vehicle using a power storage system that is one embodiment of the present invention. Figure 14
A vehicle 8400 shown in (A) is an electric vehicle that uses an electric motor as a power source for running. Alternatively, it is a hybrid vehicle in which an electric motor and an engine can be appropriately selected and used as power sources for running. By using one aspect of the present invention, a vehicle with a long cruising range can be realized. Automobile 8400 has a power storage system. The storage system can not only drive the electric motor 8406, but also power light emitting devices such as headlights 8401 and room lights (not shown).

In addition, the power storage system can supply power to display devices such as a speedometer and a tachometer included in the automobile 8400 . In addition, the power storage system can supply power to a navigation system of the automobile 8400 or the like.

An automobile 8500 shown in FIG. 14B has a power storage system 8024
The battery can be charged by receiving power supply from an external charging facility by a plug-in system, a contactless power supply system, or the like. In FIG. 14(B), a vehicle 8500 is connected to a charging device 8021 installed on the ground.
It shows a state in which a power storage system 8024 mounted on the device is being charged through a cable 8022 . When charging, the charging method and connector standards are CHAdeMO (registered trademark).
or combo, etc., as appropriate. The charging device 8021 may be a charging station provided in a commercial facility, or may be a household power source. For example, with plug-in technology, the power storage system 8024 mounted on the automobile 8500 can be charged by external power supply. Charging can be performed by converting AC power into DC power via a conversion device such as an ACDC converter.

Also, although not shown, the power receiving device can be mounted on a vehicle, and power can be supplied from a power transmission device on the ground in a non-contact manner for charging. In the case of this non-contact power supply system, it is possible to charge the battery not only while the vehicle is stopped but also while the vehicle is running by installing a power transmission device on the road or on the outer wall. In addition, electric power may be transmitted and received between vehicles using this contactless power supply method. Furthermore, a solar battery may be provided on the exterior of the vehicle to charge the power storage system while the vehicle is stopped or running. An electromagnetic induction method or a magnetic resonance method can be used for such contactless power supply.

FIG. 14C illustrates an example of a two-wheeled vehicle using the power storage system of one embodiment of the present invention.
A scooter 8600 shown in FIG.
, with turn signal lights 8603 . The power storage system 8602 can supply electricity to the turn signal lights 8603 .

Also, in the scooter 8600 shown in FIG. 14(C), the power storage system 8602 can be stored in the storage space 8604 under the seat. The power storage system 8602 can be stored in the underseat storage 8604 even if the underseat storage 8604 is small.

FIG. 15A illustrates an example of an electric bicycle using the power storage system of one embodiment of the present invention. The power storage system of one embodiment of the present invention can be applied to the electric bicycle 8700 illustrated in FIG. A power storage system of one embodiment of the present invention includes, for example, multiple storage batteries, a protection circuit, and a neural network.

The electric bicycle 8700 has a power storage system 8702 . The power storage system 8702 can supply electricity to motors that assist the driver. In addition, the power storage system 870
2 is portable, and is shown removed from the bicycle in FIG. 15(B). again,
A power storage system 8702 includes a plurality of storage batteries 8701 included in the power storage system of one embodiment of the present invention, and the remaining battery level and the like can be displayed on a display portion 8703 . The power storage system 8702 also includes a control circuit 8704 which is one embodiment of the present invention. The control circuit 8704 is electrically connected to the positive and negative electrodes of the storage battery 8701 . control circuit 870
4, the battery protection circuit shown in the previous embodiment can be used.

This embodiment can be appropriately combined with the description of other embodiments.

(Embodiment 7)
In this embodiment, an example of mounting the power storage system described in any of the above embodiments to an electronic device will be described.

Next, FIGS. 16A and 16B show an example of a tablet-type terminal (including a clamshell-type terminal) that can be folded in two. A tablet terminal 9600 illustrated in FIGS. 16A and 16B includes a housing 9630a, a housing 9630b, a movable portion 9640 connecting the housings 9630a and 9630b, a display portion 9631, and a display mode switching switch 9626. , a power switch 9627, a power saving mode switch 9625, a fastener 9629, and an operation switch 9628. By using a flexible panel for the display portion 9631, the tablet terminal can have a wider display portion. FIG. 16A shows a state in which the tablet terminal 9600 is opened, and FIG. 16B shows a state in which the tablet terminal 9600 is closed.

The tablet terminal 9600 also includes a power storage unit 9635 inside the housings 9630a and 9630b. The power storage unit 9635 is provided across the housing 9630a and the housing 9630b through the movable portion 9640.

Part of the display portion 9631 can be a touch panel region, and data can be input by touching displayed operation keys. Also, by touching the position where the keyboard display switching button on the touch panel is displayed with a finger or a stylus, the display unit 9631 can be displayed.
On the keyboard buttons can be displayed.

A display mode switching switch 9626 can switch the orientation of display such as vertical display or horizontal display, and can select switching between black-and-white display and color display. The power saving mode switching switch 9625 can optimize display luminance according to the amount of external light during use detected by a light sensor incorporated in the tablet terminal 9600 . The tablet terminal may incorporate not only the optical sensor but also other detection devices such as a sensor for detecting inclination such as a gyro and an acceleration sensor.

FIG. 16B shows a closed state, and the tablet terminal includes a housing 9630, a solar cell 9
633 and a power storage system of one embodiment of the present invention. The power storage system is controlled by the control circuit 963
4 and a power storage unit 9635 . For the control circuit 9634, the battery protection circuit described in any of the above embodiments can be used.

Note that since the tablet terminal 9600 can be folded in half, it can be folded so that the housings 9630a and 9630b overlap each other when not in use. By folding
Since the display portion 9631 can be protected, the durability of the tablet terminal 9600 can be increased.

In addition, the tablet terminals shown in FIGS. 16(A) and 16(B) have a function of displaying various information (still images, moving images, text images, etc.), a calendar, a date or time, and the like. It can have a function of displaying on the display unit, a touch input function of performing a touch input operation or editing information displayed on the display unit, a function of controlling processing by various software (programs), and the like.

A solar cell 9633 attached to the surface of the tablet terminal can supply power to a touch panel, a display portion, a video signal processing portion, or the like. Note that the solar cell 9633
It can be provided on one side or both sides of the housing 9630, so that the power storage unit 9635 can be charged efficiently.

Note that FIGS. 16A and 16B describe the structure in which the control circuit using the battery protection circuit described in the above embodiment is applied to the tablet terminal that can be folded in two, but other structures may be used. For example, as shown in FIG. 16C, application to a notebook personal computer, which is a clamshell terminal, is also possible. In FIG. 16C, the display unit 96 is mounted on the housing 9630a.
31, illustrates a notebook personal computer 9601 having a keyboard unit 9640 in a housing 9630B. In the notebook personal computer 9601, FIG.
) includes the control circuit 9634 described in (B) and the power storage unit 9635 . control circuit 963
4, the battery protection circuit shown in the previous embodiment can be used.

FIG. 17 shows an example of another electronic device. In FIG. 17, a display device 8000 is an example of an electronic device implementing the power storage system of one embodiment of the present invention. Specifically, the display device 8000 corresponds to a display device for receiving TV broadcast, and includes a housing 8001, a display portion 8002, and a speaker portion 80.
03, a secondary battery 8004, and the like. A detection system according to an aspect of the present invention includes a housing 800
1 is provided inside. The display device 8000 can receive power from a commercial power source or can use power accumulated in the secondary battery 8004 .

The display portion 8002 includes a liquid crystal display device, a light emitting device in which each pixel is provided with a light emitting element such as an organic EL element, an electrophoretic display device, a DMD (Digital Micromirror Device).
ice), PDP (Plasma Display Panel), FED (Field
A semiconductor display device such as an emission display) can be used.

A voice input device 8005 also uses a secondary battery. The voice input device 8005 is
The power storage system described in any of the above embodiments is provided. The voice input device 8005 has a plurality of sensors including microphones (optical sensor, temperature sensor, humidity sensor, air pressure sensor, illuminance sensor, motion sensor, etc.) in addition to the wireless communication element, and performs other functions according to the user's command. It is possible to operate a device such as the display device 8000, adjust the light amount of the lighting device 8100, and the like. A voice input device 8005 can operate a peripheral device by voice and can replace a manual remote controller.

In addition, the voice input device 8005 has wheels or mechanical moving means, moves in a direction in which the voice of the user can be heard, accurately hears commands with a built-in microphone, and displays the content of the commands on the display unit 8008 . , or a touch input operation on the display portion 8008 can be performed.

The voice input device 8005 can also function as a charging dock for a mobile information terminal 8009 such as a smart phone. Personal digital assistant 8009 and voice input device 8
005 enables transmission and reception of electric power in a wired or wireless manner. The portable information terminal 8009 does not need to be carried indoors, and it is desired to avoid deterioration of the secondary battery due to a load while securing a necessary capacity. It is desirable to be able to perform maintenance, etc. In addition, since the voice input device 8005 has a speaker 8007 and a microphone, hands-free conversation is possible even while the mobile information terminal 8009 is being charged. Also, when the capacity of the secondary battery of the voice input device 8005 decreases, the voice input device 8005 can be moved in the direction of the arrow and charged by wireless charging from the charging module 8010 connected to the external power supply.

Alternatively, the audio input device 8005 may be placed on the table. Also, the voice input device 800
5 may be moved to a desired position by providing wheels or mechanical moving means, or the audio input device 8005 may be fixed at a desired position, for example, on the floor without providing a stand or wheels.

The display device includes all display devices for information display, such as for TV broadcast reception, personal computer, advertisement display, and the like.

In FIG. 17, a stationary lighting device 8100 is an example of electronic equipment using a secondary battery 8103 controlled by a microprocessor (including APS) that controls charging. Specifically, the lighting device 8100 includes a housing 8101, a light source 8102, a secondary battery 8103, and the like. FIG. 17 illustrates the case where the secondary battery 8103 is provided inside the ceiling 8104 on which the housing 8101 and the light source 8102 are installed.
It may be provided inside 101 . The lighting device 8100 can receive power from a commercial power source or can use power accumulated in the secondary battery 8103 .

Note that FIG. 17 illustrates a stationary lighting device 8100 provided on the ceiling 8104, but the secondary battery 8103 is installed on a side wall 8105, a floor 8106, a window 8107, etc. other than the ceiling 8104. It can also be used for a lighting device, and it can also be used for a desktop lighting device or the like.

For the light source 8102, an artificial light source that artificially obtains light using electric power can be used. Specifically, incandescent lamps, discharge lamps such as fluorescent lamps, and light-emitting elements such as LEDs and organic EL elements are examples of the artificial light sources.

An air conditioner having an indoor unit 8200 and an outdoor unit 8204 in FIG. 17 is an example of an electronic device using a secondary battery 8203 . Specifically, the indoor unit 8200 has a housing 8201, a blower port 8202, a secondary battery 8203, and the like. In FIG. 17, the secondary battery 820
3 is provided in the indoor unit 8200 , the secondary battery 8203 may be provided in the outdoor unit 8204 . Alternatively, both the indoor unit 8200 and the outdoor unit 8204 may be provided with the secondary battery 8203 . The air conditioner can receive power from a commercial power source or can use power accumulated in the secondary battery 8203 .

In FIG. 17, an electric refrigerator-freezer 8300 is an example of electronic equipment using a secondary battery 8304 . Specifically, the electric refrigerator-freezer 8300 includes a housing 8301, a refrigerator compartment door 8302,
It has a freezer compartment door 8303, a secondary battery 8304, and the like. In FIG. 17, the secondary battery 8304 is
It is provided inside the housing 8301 . The electric refrigerator-freezer 8300 can receive power from a commercial power source, or can use power stored in a secondary battery 8304 .

In addition, during times when electronic equipment is not used, especially during times when the ratio of the amount of power actually used to the total power that can be supplied by commercial power supply sources (called the power usage rate) is low, By storing electric power in the secondary battery, it is possible to suppress an increase in the electric power usage rate during periods other than the above time period. For example, in the case of the electric freezer-refrigerator 8300, the temperature is low and the refrigerator compartment door 83 is closed.
02, power is stored in the secondary battery 8304 at night when the freezer compartment door 8303 is not opened and closed. In the daytime when the temperature rises and the refrigerator compartment door 8302 and the freezer compartment door 8303 are opened and closed, the secondary battery 8304 is used as an auxiliary power supply, so that the power usage rate during the daytime can be kept low.

In addition to the electronic devices described above, the secondary battery can be mounted in any electronic device. According to one embodiment of the present invention, cycle characteristics of a secondary battery are improved. Therefore, by incorporating a microprocessor (including an APS) that controls charging, which is one embodiment of the present invention, in the electronic device described in this embodiment, the electronic device can have a longer life. This embodiment can be implemented in appropriate combination with other embodiments.

FIGS. 18A to 18E show examples in which the power storage system of one embodiment of the present invention is implemented in electronic devices. Examples of electronic devices to which the power storage system of one embodiment of the present invention is applied include television devices (also referred to as television sets or television receivers), computer monitors, digital cameras, digital video cameras, digital photo frames, and mobile phones. Examples include telephones (also called mobile phones and mobile phone devices), portable game machines, personal digital assistants, sound reproducing devices, and large game machines such as pachinko machines.

FIG. 18A shows an example of a mobile phone. A mobile phone 7400 includes a housing 740
1, an operation button 7403, an external connection port 7404,
A speaker 7405, a microphone 7406, and the like are provided. Note that mobile phone 7400 includes a power storage system of one embodiment of the present invention. A power storage system of one embodiment of the present invention includes, for example, the storage battery 7407 and the battery protection circuit described in any of the above embodiments.

FIG. 18B shows a state in which the mobile phone 7400 is bent. mobile phone 74
00 is deformed by an external force and bent as a whole, the storage battery 7407 provided therein may also be bent. In such a case, a flexible storage battery is preferably used as the storage battery 7407 . FIG. 1 shows a bent state of a flexible storage battery.
8(C). A control circuit 7408 is electrically connected to the storage battery. control circuit 74
As 08, the battery protection circuit shown in the previous embodiment can be used.

It is also possible to incorporate the storage battery having a flexible shape along the inner or outer wall of a house or building, or along the curved surface of the interior or exterior of an automobile.

FIG. 18D illustrates an example of a bangle-type display device. A portable display device 7100 includes a housing 7101, a display portion 7102, operation buttons 7103, and a power storage system of one embodiment of the present invention. A power storage system of one embodiment of the present invention includes, for example, the storage battery 7104 and the battery protection circuit described in any of the above embodiments.

FIG. 18E shows an example of a wristwatch-type portable information terminal. Portable information terminal 7200
, a housing 7201, a display unit 7202, a band 7203, a buckle 7204, and operation buttons 7
205, an input/output terminal 7206, and the like.

Personal digital assistant 7200 is capable of running a variety of applications such as mobile phones, e-mail, text viewing and composition, music playback, Internet communication, computer games, and the like.

The display portion 7202 has a curved display surface, and can perform display along the curved display surface. The display portion 7202 includes a touch sensor and can be operated by touching the screen with a finger, a stylus, or the like. For example, icon 7 displayed on the display unit 7202
An application can be launched by touching 207 .

The operation button 7205 can have various functions such as time setting, power on/off operation, wireless communication on/off operation, manner mode execution/cancellation, and power saving mode execution/cancellation. . For example, an operating system installed in the mobile information terminal 7200 can freely set the functions of the operation buttons 7205 .

In addition, the mobile information terminal 7200 is capable of performing short-range wireless communication according to communication standards. For example, by intercommunicating with a headset capable of wireless communication, hands-free communication is also possible.

In addition, the portable information terminal 7200 has an input/output terminal 7206 and can directly exchange data with another information terminal through a connector. Also, charging can be performed through the input/output terminal 7206 . Note that the charging operation may be performed by wireless power supply without using the input/output terminal 7206 .

A mobile information terminal 7200 includes a power storage system of one embodiment of the present invention. The power storage system has a storage battery and the battery protection circuit described in the previous embodiment.

Personal digital assistant 7200 preferably has a sensor. As sensors, for example, it is preferable to mount a human body sensor such as a fingerprint sensor, a pulse sensor, a body temperature sensor, a touch sensor, a pressure sensor, an acceleration sensor, and the like.

This embodiment can be appropriately combined with the description of other embodiments.

(Additional remarks regarding descriptions in this specification, etc.)
Description of the above embodiment and each configuration in the embodiment will be added below.

The structure described in each embodiment can be combined with any structure described in another embodiment as appropriate to be one embodiment of the present invention. Moreover, when a plurality of configuration examples are shown in one embodiment, the configuration examples can be combined as appropriate.

In addition, the content (may be part of the content) described in one embodiment may be another content (may be part of the content) described in the embodiment, and/or one or more The contents described in another embodiment (or part of the contents) can be applied, combined, or replaced.

The content described in the embodiments means the content described using various drawings or the text described in the specification in each embodiment.

It should be noted that a drawing (may be a part) described in one embodiment refers to another part of the drawing, another drawing (may be a part) described in the embodiment, and/or one or more By combining the figures (or part of them) described in another embodiment, more figures can be configured.

Also, in this specification and the like, in block diagrams, constituent elements are classified by function and shown as blocks independent of each other. However, in an actual circuit or the like, it is difficult to separate the constituent elements according to their functions, and there may be cases where one circuit is associated with a plurality of functions or a single function is associated with a plurality of circuits. As such, the blocks in the block diagrams are not limited to the components described in the specification and may be interchanged as appropriate depending on the context.

In the drawings, sizes, layer thicknesses, and regions are shown as arbitrary sizes for convenience of explanation. Therefore, it is not necessarily limited to that scale. Note that the drawings are shown schematically for clarity, and are not limited to the shapes or values shown in the drawings. For example, variations in signal, voltage, or current due to noise, or variations in signal, voltage, or current due to timing shift can be included.

In this specification and the like, when describing the connection relationship of a transistor, "one of the source or the drain" (or the first electrode or the first terminal) and the other of the source and the drain are referred to as the "other of the source or the drain" (or The notation “second electrode or second terminal” is used. This is because the source and drain of a transistor change depending on the structure or operating conditions of the transistor. Regarding the names of the source and drain of a transistor, the source (drain) terminal,
Source (drain) electrode or the like can be appropriately rephrased depending on the situation.

In addition, the terms “electrode” and “wiring” in this specification and the like do not functionally limit these constituent elements. For example, an "electrode" may be used as part of a "wiring" and vice versa. Furthermore, the terms "electrode" and "wiring" are used to refer to multiple "electrodes" and "
It also includes the case where "wiring" is integrally formed.

In this specification and the like, voltage and potential can be interchanged as appropriate. A voltage is a potential difference from a reference potential. For example, if the reference potential is a ground voltage, the voltage can be translated into a potential. Ground potential is not always 0V
does not necessarily mean The potential is relative, and depending on the reference potential,
In some cases, the potential applied to wiring or the like is changed.

Note that in this specification and the like, terms such as “film” and “layer” can be interchanged depending on the case or situation. For example, the term "conductive layer" may be defined as "
It may be possible to change the term to "conductive film". Or, for example, it may be possible to change the term "insulating film" to the term "insulating layer".

In this specification and the like, a switch has a function of being in a conducting state (on state) or a non-conducting state (off state) and controlling whether or not current flows. or,
A switch has a function of selecting and switching a path through which a current flows.

In this specification and the like, the channel length means, for example, a region in which a semiconductor (or a portion of the semiconductor in which current flows when the transistor is on) overlaps with a gate in a top view of a transistor, or a channel is formed. The distance between the source and the drain in the area where the

In this specification and the like, the channel width refers to, for example, a region where a semiconductor (or a portion of the semiconductor in which current flows when the transistor is on) overlaps with a gate electrode, or a region where a channel is formed. is the length of the part where the drain and the drain face each other.

In this specification and the like, "A and B are connected" includes not only direct connection between A and B, but also electrical connection. Here, A and B are electrically connected means that when there is an object having some kind of electrical action between A and B, it is possible for A and B to transmit and receive electrical signals. What to say.

100 power storage device 110 battery protection circuit 111 voltage comparison unit 112 arithmetic circuit 113 comparator 114 storage circuit 114A storage circuit 114C storage circuit 115 reference voltage generation circuit 116 memory control circuit 117 sensor 120 assembled battery 121 battery cell 130 cell balance circuit unit 130A cell balance Circuit 131 Resistance element 132 Transistor 133 Cell balance control circuit 140 Transistor 150 Transistor

Claims (3)

A battery protection circuit for an assembled battery comprising a plurality of battery cells,
a function of holding a reference voltage by having a transistor and turning off the transistor;
a function of inputting the terminal voltage of the battery cell and the reference voltage and outputting a comparison result;
and a function of controlling the voltage or current supplied to the assembled battery according to the output. In claim 1,
The battery protection circuit, wherein the transistor includes an oxide semiconductor in a channel formation region. In claim 1 or claim 2,
A power storage device including the assembled battery and the battery protection circuit.

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