Control circuit for secondary battery

Abstract

To provide a control circuit for a secondary battery with a novel configuration.SOLUTION: A control circuit for a secondary battery has a first transistor, a first voltage generation circuit that generates a first voltage, and a second voltage generation circuit that generates a second voltage. The first voltage generation circuit has a second transistor and a first capacitor. The second voltage generation circuit has a third transistor and a second capacitor. A difference between the first voltage and the second voltage is set according to a threshold voltage of the first transistor. When the first transistor has a back gate, the control circuit has a voltage holding circuit that has a function of maintaining a voltage of the back gate. The voltage holding circuit has a fourth transistor and a third capacitor. The third capacitor has a ferroelectric layer between a pair of electrodes. The third capacitor holds the voltage applied to the back gate by applying a voltage that causes polarization inversion in the ferroelectric layer.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] One aspect of the present invention relates to a control circuit for a secondary battery.

[0002] Note that one embodiment of the present invention is not limited to the above technical field. Examples of the technical field of one embodiment of the present invention disclosed in this specification and the like include semiconductor devices, imaging devices, display devices, light-emitting devices, power storage devices, memory devices, display systems, electronic devices, lighting devices, input devices, input / output devices, and driving methods thereof or manufacturing methods thereof. Note that a semiconductor device generally refers to a device that utilizes semiconductor characteristics, and a control circuit for a secondary battery is a semiconductor device. [Background technology]

[0003] Secondary batteries (also called batteries or power storage devices) are now used in a wide range of fields, from small electronic devices to automobiles.

[0004] A secondary battery is equipped with a control circuit for managing charging and discharging to prevent abnormalities during charging and discharging, such as over-discharging, over-charging, overcurrent, or short circuit. The control circuit acquires data such as voltage and current to manage the charging and discharging of the secondary battery. The control circuit controls charging and discharging based on the observed data.

[0005] Patent Document 1 discloses a protection monitoring circuit that functions as a control circuit for a secondary battery. The protection monitoring circuit described in Patent Document 1 discloses a configuration in which multiple comparators are provided internally and a reference voltage is compared with the voltage at the terminal to which the secondary battery is connected to detect abnormalities during charging and discharging.

[0006] Patent Document 2 also discloses a control device that performs trickle charging to compensate for the decrease in secondary battery capacity due to natural discharge of the secondary battery. The control device in Patent Document 2 discloses a configuration in which an upper limit voltage and a lower limit voltage are set, and control is performed to repeatedly switch between a charging state and a cut-off state within the set voltage range. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] US Patent Application Publication No. 2011 / 267726 [Patent Document 2] Japanese Patent Application Laid-Open No. 2017-175688 Summary of the Invention [Problem to be solved by the invention]

[0008] The natural discharge rate of a secondary battery varies depending on factors such as the temperature during use and aging. For example, the natural discharge rate increases in high-temperature environments. Therefore, the upper and lower limit voltages set by the control circuit must be switched according to the environment of the secondary battery. In this case, multiple voltages are required to set the upper and lower limit voltages. The multiple voltages are generated by a constant voltage generation circuit that generates the desired voltages using resistor division. The generated voltages are set as upper and lower limit voltages and compared with the voltage of the secondary battery. Multiple comparators (comparison circuits) are required to compare the multiple voltages with the voltage of the secondary battery. A control circuit configuration that includes a constant voltage generation circuit that generates multiple voltages and multiple comparators may result in increased power consumption.

[0009] An object of one embodiment of the present invention is to provide a novel secondary battery control circuit or the like. Alternatively, an object of one embodiment of the present invention is to provide a novel secondary battery control circuit or the like that can reduce power consumption.

[0010] The problems of one embodiment of the present invention are not limited to the problems listed above. The problems listed above do not preclude the existence of other problems. The other problems are problems not mentioned in this section, which will be described below. Problems not mentioned in this section can be derived by a person skilled in the art from the description in the specification or drawings, and can be extracted as appropriate from these descriptions. One embodiment of the present invention solves at least one of the problems listed above and / or other problems. [Means for solving the problem]

[0011] One aspect of the present invention is a control circuit for a secondary battery having a first transistor, a first voltage generation circuit that generates a first voltage, and a second voltage generation circuit that generates a second voltage, wherein the first voltage generation circuit has a second transistor and a first capacitance, and the second voltage generation circuit has a third transistor and a second capacitance, and the difference between the first voltage and the second voltage is set according to the threshold voltage of the first transistor.

[0012] One embodiment of the present invention is a control circuit for a secondary battery comprising a first transistor, a first voltage generation circuit that generates a first voltage, a second voltage generation circuit that generates a second voltage, and a voltage holding circuit, wherein the first voltage generation circuit has a second transistor and a first capacitance, the second voltage generation circuit has a third transistor and a second capacitance, the first transistor has a back gate, the voltage holding circuit has a function of holding the voltage of the back gate, and the difference between the first voltage and the second voltage is set according to the threshold voltage of the first transistor.

[0013] In one aspect of the present invention, the voltage holding circuit is preferably a control circuit for a secondary battery, which has a fourth transistor and a third capacitor, the third capacitor having a ferroelectric layer between a pair of electrodes, and the third capacitor holds a voltage to be applied to the back gate by applying a voltage that reverses the polarization of the ferroelectric layer.

[0014] In one embodiment of the present invention, the ferroelectric layer preferably has hafnium oxide and / or zirconium oxide, and is used in a control circuit for a secondary battery.

[0015] In one embodiment of the present invention, the first to third transistors are transistors including an oxide semiconductor in the channel in a control circuit for a secondary battery.

[0016] In one embodiment of the present invention, the first to third transistors are transistors having silicon in their channels in a control circuit for a secondary battery.

[0017] One embodiment of the present invention is an electrical device including the above-described control circuit for a secondary battery, the secondary battery, and a housing.

[0018] Other aspects of the present invention will be described in the following embodiments and in the drawings. [Effects of the Invention]

[0019] One embodiment of the present invention can provide a novel control circuit for a secondary battery or the like. Alternatively, one embodiment of the present invention can provide a novel control circuit for a secondary battery or the like that can reduce power consumption.

[0020] 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. The other effects are described below and are not mentioned in this section. Effects not mentioned in this section can be derived by a person skilled in the art from the description in the specification or drawings, and can be extracted as appropriate from these descriptions. One embodiment of the present invention has at least one of the effects listed above and / or other effects. Therefore, one embodiment of the present invention may not have the effects listed above in some cases. [Brief explanation of the drawings]

[0021] [Figure 1] 1A and 1B are diagrams illustrating an example of the configuration of a semiconductor device. [Figure 2] 2A and 2B are diagrams showing an example of the configuration of a semiconductor device. [Figure 3] FIG. 3 is a diagram illustrating a configuration example of a semiconductor device. [Figure 4] 4A, 4B, and 4C are diagrams showing configuration examples of a semiconductor device. [Figure 5] FIG. 5 is a diagram showing the hysteresis characteristics of a ferroelectric material. [Figure 6] 6A and 6B are diagrams illustrating an example of the configuration of a semiconductor device. [Figure 7] 7A and 7B are diagrams illustrating an example of the configuration of a semiconductor device. [Figure 8] 8A and 8B are diagrams illustrating an example of the configuration of a control circuit for a secondary battery. [Figure 9] FIG. 9 is a diagram illustrating an example of the configuration of a control circuit for a secondary battery. [Figure 10] FIG. 10 is a diagram illustrating an example of the configuration of a control circuit for a secondary battery. [Figure 11] 11A and 11B are diagrams illustrating an example of the configuration of a control circuit for a secondary battery. [Figure 12] FIG. 12 is a schematic cross-sectional view showing a configuration example of a semiconductor device. [Figure 13] 13A to 13C are cross-sectional views showing examples of the structure of a transistor. [Figure 14] FIG. 14 is a schematic cross-sectional view showing a configuration example of a semiconductor device. [Figure 15] 15A and 15B are cross-sectional views showing examples of the structure of a transistor. [Figure 16] FIG. 16 is a schematic cross-sectional view showing a configuration example of a transistor. [Figure 17] 17A to 17C are cross-sectional views showing examples of the structure of a transistor. [Figure 18] FIG. 18 is a schematic cross-sectional view showing a configuration example of a transistor. [Figure 19] 19A and 19B are cross-sectional views showing examples of the structure of a transistor. [Figure 20] 20A and 20B are cross-sectional views showing examples of the structure of a transistor. [Figure 21] FIG. 21A is a diagram illustrating the classification of IGZO crystal structures, FIG. 21B is a diagram illustrating the XRD spectrum of crystalline IGZO, and FIG. 21C is a diagram illustrating the electron microbeam diffraction pattern of crystalline IGZO. [Figure 22] FIG. 22 is a diagram showing an example of an electronic component. [Figure 23]23A, 23B, 23C, and 23D are diagrams illustrating examples of secondary batteries. [Figure 24] 24A, 24B, and 24C are diagrams illustrating examples of secondary batteries. [Figure 25] 25A, 25B, and 25C are diagrams illustrating examples of secondary batteries. [Figure 26] 26A, 26B, and 26C illustrate an electrical device according to one embodiment of the present invention. [Figure 27] 27A and 27B illustrate an electrical device of one embodiment of the present invention. [Figure 28] 28A, 28B, and 28C illustrate an electrical device according to one embodiment of the present invention. [Figure 29] FIG. 29 illustrates an electrical device according to one embodiment of the present invention. [Figure 30] 30A, 30B, 30C, 30D, and 30E are diagrams showing electronic devices. [Figure 31] 31A, 31B, 31C, and 31D are diagrams illustrating electronic devices. [Figure 32] 32A and 32B are diagrams for explaining the system. DETAILED DESCRIPTION OF THE INVENTION

[0022] Hereinafter, embodiments will be described with reference to the drawings. However, it will be readily understood by those skilled in the art that the embodiments can be implemented in many different ways and that various changes in form and details can be made without departing from the spirit and scope of the present invention. Therefore, the present invention should not be interpreted as being limited to the following description of the embodiments.

[0023] In this specification, the ordinal numbers "first," "second," and "third" are used to avoid confusion between components. Therefore, they do not limit the number of components. Furthermore, they do not limit the order of the components. For example, a component referred to as "first" in one embodiment of this specification may be a component referred to as "second" in another embodiment or in the claims. For example, a component referred to as "first" in one embodiment of this specification may be omitted in another embodiment or in the claims.

[0024] In the drawings, the same elements or elements having similar functions, elements made of the same material, or elements formed at the same time may be given the same reference numerals, and repeated explanations thereof may be omitted.

[0025] In this specification and the like, the term "metal oxide" refers to an oxide of a metal in a broad sense. Metal oxides are classified into oxide insulators, oxide conductors (including transparent oxide conductors), oxide semiconductors (also referred to as "oxide semiconductors" or simply as "OSs"). For example, when a metal oxide is used in an active layer of a transistor, the metal oxide may be referred to as an oxide semiconductor. That is, when a metal oxide can form a channel formation region of a transistor having at least one of an amplifying function, a rectifying function, and a switching function, the metal oxide can be referred to as a metal oxide semiconductor. Furthermore, when the term "OS FET" or "OS transistor" is used, it can be rephrased as a transistor having a metal oxide or an oxide semiconductor.

[0026] (Embodiment 1) The configuration of a control circuit for a secondary battery will be described with reference to FIGS.

[0027] FIG. 1A shows the configuration of a semiconductor device 100 included in a control circuit for a secondary battery. The semiconductor device 100 is a circuit that can be used in a control circuit for a secondary battery. The semiconductor device 100 includes a transistor M1, a transistor M2, a transistor M3, a capacitor C1, and a capacitor C2. The semiconductor device 100 is connected to an input voltage V IN is given, and the output voltage V OUT1 and the output voltage V OUT2 It has the function of outputting.

[0028] The gate, source, and drain of the transistor M1 and the source and drain of the transistor M2 are connected to an input voltage V IN A selection signal S is applied to the gate of the transistor M2 and the gate of the transistor M3. The other of the source and drain of the transistor M1 is connected to one of the source and drain of the transistor M3. The other of the source and drain of the transistor M2 is connected to a capacitor C1, and an output voltage V OUT1 The other of the source and drain of the transistor M3 is connected to the capacitor C2, and the output voltage V OUT2 Give.

[0029] A back gate potential BG1 is applied to the back gate of the transistor M1. A back gate potential BG2 is applied to the back gate of the transistor M2. A back gate potential BG3 is applied to the back gate of the transistor M3. The back gate potential BG1 is a potential that is lower than the threshold voltage (V TH ) The back gate potentials BG2 and BG3 are potentials for controlling the leakage current (off current) that flows when the transistors M2 and M3 are turned off so that the charges held in the capacitors C1 and C2 are maintained. The selection signal S is a signal for switching the transistors M2 and M3 on and off when they are operated as switches.

[0030] Output voltage V OUT1 is the input voltage V IN If V1 is used, then V1 is the output voltage. OUT2is the threshold voltage V of transistor M1 TH minutes, V1-V TH That is, the semiconductor device 100 is configured such that the input voltage V1 and the threshold voltage V of the transistor M1 are TH V1-V decreased by 1 minute TH and has the function of generating.

[0031] In one embodiment of the present invention, the transistors M1 to M3 are configured to hold the generated voltage when turned off. The transistors M1 to M3 can be transistors whose channel formation region includes silicon (hereinafter referred to as Si transistors) and / or transistors whose channel formation region includes an oxide semiconductor (hereinafter referred to as OS transistors). In particular, the transistors M1 to M3 are preferably OS transistors.

[0032] Silicon used for the channel formation region of a Si transistor can be, for example, amorphous silicon (sometimes referred to as hydrogenated amorphous silicon), microcrystalline silicon, polycrystalline silicon, single crystal silicon, etc. As the transistors M1 to M3, in addition to OS transistors and Si transistors, transistors whose channel formation region includes Ge or the like, transistors whose channel formation region includes a compound semiconductor such as ZnSe, CdS, GaAs, InP, GaN, or SiGe, transistors whose channel formation region includes a carbon nanotube, transistors whose channel formation region includes an organic semiconductor, etc. can be used.

[0033] In one embodiment of the present invention, OS transistors are used as the transistors M1 to M3, and thus the output voltage V OUT1 , output voltage V OUT2 The capacitances C1 and C2 can hold charges corresponding to the

[0034] Furthermore, OS transistors can be freely arranged by stacking them on circuits using Si transistors, which facilitates integration. Examples of silicon that can be used include amorphous silicon (sometimes called hydrogenated amorphous silicon), microcrystalline silicon, polycrystalline silicon, and single-crystal silicon. Furthermore, OS transistors can be manufactured using the same manufacturing equipment as Si transistors, which allows for low-cost manufacturing.

[0035] Furthermore, OS transistors have better electrical characteristics than Si transistors in high-temperature environments. Specifically, they have a large ratio of on-current to off-current even at high temperatures of 100° C. to 200° C., preferably 125° C. to 150° C., and therefore can perform good switching operations.

[0036] 1B is a diagram illustrating the operation of the semiconductor device 100 included in the control circuit of the secondary battery. In the explanation of FIG. 1B, the transistors M1 to M3 are n-channel transistors, that is, they are turned on when the signal is at H level and turned off when the signal is at L level. In FIG. 1B, the input voltage V IN , selection signal S, output voltage V OUT1 , and the output voltage V OUT2 The figure shows the situation.

[0037] At time P0, the input voltage V IN When the voltage V1 is set to V, a current flows through the transistor M1. The node between the transistors M1 and M3 (node ​​N1 in FIG. 1A) is connected to the threshold voltage (V TH ) is the potential V1-V TH This becomes:

[0038] When the selection signal is set to H level at time P1, current flows through transistors M2 and M3, i.e., they are turned on. As capacitors C1 and C2 are charged, the output voltage V OUT1 is V1, and the output voltage V OUT2 is V1-V TH The semiconductor device 100 receives an input voltage VIN and the threshold voltage of transistor M1 (V TH ) and a voltage that has been reduced. That is, the transistor M2 and the capacitor C1, and the transistors M1, M3 and the capacitor C2 in the semiconductor device 100 can function as constant voltage generating circuits that generate different voltages. Note that the voltage difference between the two constant voltage generating circuits that make a pair (constant voltage generating circuit pair) is the threshold voltage of the transistor M1, so the voltage output by the constant voltage generating circuit pair can be adjusted by adjusting the threshold voltage of the transistor M1.

[0039] Although the semiconductor device 100 is illustrated as being configured to apply the back-gate potentials BG2 and BG3 from separate terminals, other configurations are also possible. For example, as illustrated in FIG. 2A for the semiconductor device 100A, the back-gate potential BG2 may be applied as a common potential to the back-gates of the transistors M2 and M3. This configuration allows the wiring for applying the back-gate potential to be shortened.

[0040] The output voltage V as described in Figures 1A and 1B OUT1 and the output voltage V OUT2 can be used in control circuits to prevent overcharging and overdischarging of secondary batteries such as lithium-ion batteries. The control circuit for a secondary battery has the function of generating a signal to electrically cut off the connection between the secondary battery and a load (for example, an electronic device such as a mobile terminal) or the secondary battery and a charger when the voltage of the secondary battery exceeds or falls below a desired voltage. The output voltage V OUT1 and the output voltage V OUT2 can be used as the upper and lower limit voltages for determining whether the secondary battery is overcharged or overdischarged.

[0041] This configuration allows for a reduction in the size of a constant voltage generation circuit that generates a desired voltage as a reference voltage such as an upper limit voltage or a lower limit voltage. A constant voltage generation circuit that generates a desired voltage by resistively dividing a voltage generated by a regulator, a digital-to-analog converter (DAC), or the like may increase power consumption. In particular, when multiple reference voltages such as upper limit voltages and lower limit voltages are required depending on temperature changes or the like, a constant voltage generation circuit that generates multiple desired voltages is required. In one embodiment of the present invention, the threshold voltage of a transistor is set to correspond to the difference between the upper limit voltage and the lower limit voltage, and the generated output voltage V OUT1 and the output voltage V OUT2 Since the capacitance can be held, a circuit that generates a voltage, such as a DAC, can be configured to operate intermittently.

[0042] According to one embodiment of the present invention, multiple combinations of upper and lower limit voltages can be generated. To prevent overcharging, charging is stopped when the voltage of the secondary battery exceeds the upper limit voltage of overcharging, and the next charging is permitted when the voltage falls below the lower limit voltage of overcharging. This allows switching the voltage for such operations based on the input voltage and the threshold voltage of the transistor. This allows optimization of on / off of charging, thereby reducing the burden on the secondary battery. Similarly, optimization of on / off of discharging can also reduce the burden on the secondary battery.

[0043] Although the semiconductor device 100 is illustrated as having one transistor functioning as the transistor M1, other configurations are also possible. For example, as illustrated in FIG. 2B as the semiconductor device 100B, a configuration may be adopted in which a transistor M1A and a transistor M1B function as the transistor M1. With this configuration, the semiconductor device 100B can be configured to operate in a manner similar to that of the semiconductor device 100A, but with a voltage V IN and two threshold voltages of transistors M1A and M1B (2V TH ) and the output voltage V OUT1 is V1, and the output voltage V OUT2 is V1-2VTH It can be said that:

[0044] When the semiconductor device 100 is made to function as a constant voltage generating circuit that generates a desired voltage, the output voltage V OUT1 and the output voltage V OUT2 The threshold voltage V of transistor M1 corresponds to the difference between TH As an example, in a semiconductor device 100C shown in Fig. 3, the voltage holding circuit VC has a function of holding and controlling the back gate potential BG1 of the transistor M1.

[0045] By providing a voltage holding circuit VC that holds and controls the back-gate potential BG1 of the transistor M1, the voltage generating circuit that generates the back-gate potential BG1 can be configured to operate intermittently. This allows for reduced power consumption in the control circuit of a secondary battery that includes a semiconductor device. Furthermore, by configuring the back-gate potential BG1 of the transistor M1 to be adjusted, the threshold voltage V of the transistor M1 can be reduced. TH Therefore, the output voltage V OUT2 V1-V is generated as TH can be adjusted.

[0046] An example of the configuration of the voltage holding circuit VC shown in FIG. 3 will be described with reference to FIGS. 4A to 4C and 5. FIG.

[0047] The voltage holding circuit VC shown in FIG. 4A includes a voltage generating circuit VGEN, a transistor M4, and a capacitor C3. A signal SC is applied to the gate of the transistor M4, which functions as a switch, to control the on / off state of the transistor M4. One of the source and drain of the transistor M4 is connected to the voltage generating circuit VGEN. The other of the source and drain of the transistor M4 is connected to the back gate of the transistor M1. The capacitor C3 is provided to hold a back gate potential BG1 applied to the back gate of the transistor M1.

[0048] The transistor M4 is preferably an OS transistor. By using an OS transistor as the transistor M4, an electric charge corresponding to the back-gate potential BG1 can be stored in the capacitor C3 by utilizing the extremely low off-state current of the OS transistor. Furthermore, by storing an electric charge corresponding to the back-gate potential BG1 in the capacitor C3, power can be supplied to the voltage generating circuit VGEN intermittently, thereby achieving low power consumption.

[0049] The OS transistor can also be placed on a circuit composed of Si transistors. The voltage generation circuit VGEN can be composed of Si transistors, and the transistor M4 and capacitor C3 can be placed on top of it. This allows the voltage hold circuit VC to be made smaller.

[0050] Furthermore, the capacitor C3 shown in FIG. 4A preferably has a ferroelectric layer between a pair of electrodes. A capacitor with a ferroelectric layer can maintain the voltage applied to the back gate by applying a voltage that reverses the polarization. Furthermore, a capacitor with a ferroelectric layer can increase the capacitance value, thereby increasing the amount of charge that can be stored. This reduces the potential fluctuations associated with charge leakage from the capacitor C3. The back gate potential BG1 provided by the voltage generation circuit VGEN can be maintained for a long period of time. This allows the period during which power supply to the voltage generation circuit VGEN is intermittently stopped to be extended, thereby reducing power consumption.

[0051] Fig. 4B shows a configuration in which the capacitor C3 shown in Fig. 4A is replaced with a capacitor FC3 having a ferroelectric layer. The capacitor FC3 shown in Fig. 4B is shown as a symbol having a ferroelectric layer.

[0052] Furthermore, the transistor M4 shown in Fig. 4A preferably has a ferroelectric layer between the gate and the channel formation region or between the back gate and the channel formation region. Fig. 4C shows a configuration in which the transistor M4 shown in Fig. 4A is replaced by a transistor FM4 having a ferroelectric layer. The transistor FM4 shown in Fig. 4C is symbolized as having a ferroelectric layer.

[0053] The ferroelectric layer of the capacitor FC3 is sandwiched between a pair of electrodes and has a region in contact with the corresponding electrode.

[0054] Materials that can have ferroelectric properties include hafnium oxide, zirconium oxide, and HfZrO X (X is a real number greater than 0), hafnium oxide to which element J1 (here, element J1 is zirconium (Zr), silicon (Si), aluminum (Al), gadolinium (Gd), yttrium (Y), lanthanum (La), strontium (Sr), etc.) is added, and zirconium oxide to which element J2 (here, element J2 is hafnium (Hf), silicon (Si), aluminum (Al), gadolinium (Gd), yttrium (Y), lanthanum (La), strontium (Sr), etc.) is added. Furthermore, materials that may have ferroelectricity include PbTiO X Piezoelectric ceramics having a perovskite structure, such as barium strontium titanate (BST), strontium titanate, lead zirconate titanate (PZT), strontium bismuth tantalate (SBT), bismuth ferrite (BFO), and barium titanate, may also be used. Ferroelectric materials may be, for example, a plurality of materials selected from the above-listed materials, or a laminated structure made of a plurality of materials selected from the above-listed materials. Incidentally, hafnium oxide, zirconium oxide, HfZrO Xand materials in which the element J1 is added to hafnium oxide, the crystal structure (characteristics) of which may change not only depending on the film formation conditions but also on various processes, etc., and therefore in this specification and the like, materials that exhibit ferroelectricity are not only called ferroelectrics, but are also called materials that can have ferroelectricity or materials that can be made to have ferroelectricity.

[0055] Among these, hafnium oxide, or hafnium oxide and zirconium oxide, is preferred as a material for the ferroelectric layer because it can retain ferroelectricity even when processed into a thin film of a few nanometers. Here, the film thickness of the ferroelectric layer can be 100 nm or less, preferably 50 nm or less, more preferably 20 nm or less, and even more preferably 10 nm or less (typically 2 nm to 9 nm). By using a ferroelectric layer that can be thinned, a semiconductor device can be formed in combination with a miniaturized transistor.

[0056] The ferroelectric layer is an insulator, and has a property (hysteresis characteristic) in which polarization occurs inside when an electric field is applied from the outside, and the polarization remains even when the electric field is removed to zero.

[0057] FIG. 5 is a graph showing the hysteresis characteristics of a ferroelectric layer. In FIG. 5, the horizontal axis represents the voltage applied to the ferroelectric layer, and the vertical axis represents the polarization amount of the ferroelectric layer. As shown in FIG. 5, the hysteresis characteristics of the ferroelectric layer can be represented by curves R1 and R2. The voltages at the intersections of curves R1 and R2 are designated as voltages VPI1 and VPI2. In FIG. 5, voltage VPI1 is negative and voltage VPI2 is positive.

[0058] After applying voltage VPI1 to the ferroelectric layer, if the voltage applied to the ferroelectric layer is increased, the amount of polarization in the ferroelectric layer increases according to curve R1. On the other hand, after applying voltage VPI2 to the ferroelectric layer, if the voltage applied to the ferroelectric layer is decreased, the amount of polarization in the ferroelectric layer decreases according to curve R2. In other words, if voltage VPI1 or voltage VPI2 is applied to the ferroelectric layer, polarization reversal occurs. Voltages VPI1 and VPI2 can be called polarization reversal voltages.

[0059] In Figure 5, when the polarization amount is positive, positive charges are biased toward one electrode of the capacitor, and negative charges are biased toward the other electrode of the capacitor. Also, when the polarization amount is negative, negative charges are biased toward one electrode, and positive charges are biased toward the other electrode. By using a ferroelectric layer as a capacitor, a potential corresponding to the positive or negative polarization amount can be maintained as the back gate potential BG1. This reduces the operation frequency of the voltage generation circuit VGEN, and reduces the power consumption of the voltage generation circuit VGEN.

[0060] The capacitors C1 and C2 described in FIG. 1A may be configured as capacitors having a ferroelectric layer as described in FIG. 4B. For example, as shown in FIG. 6A as a semiconductor device 100D, a configuration can be adopted in which capacitors FC1 and FC2 are configured as capacitors having a ferroelectric layer. By adopting this configuration, the capacitance value of the capacitors can be increased, and therefore the output voltage V OUT1 and the output voltage V OUT2 This makes it easier to hold a charge according to the amount of charge.

[0061] The transistor M2 and the transistor M3 described in FIG. 1A may be configured as the transistor having a ferroelectric layer described in FIG. 4C. For example, as shown in FIG. 6B as a semiconductor device 100E, a configuration can be adopted in which the transistors FM2 and FM3 are configured as transistors having a ferroelectric layer. By adopting such a configuration, it is possible to control transistor characteristics such as the threshold voltage, and therefore the output voltage V OUT1 and the output voltage V OUT2This makes it easier to hold a charge according to the amount of charge.

[0062] 6A, the operation of the semiconductor device 100D, which differs from that of the semiconductor device 100, will be described with reference to FIGS. 7A and 7B. As shown in FIG. 7A, in the semiconductor device 100D, the input voltage V IN The voltage (V1) at the output of transistor M1 is lowered by the threshold voltage of transistor M1 (V1-V TH ) are applied to the capacitors FC1 and FC2 by the selection signal S. That is, different voltages are applied to the capacitors FC1 and FC2.

[0063] The capacitors FC1 and FC2, which have ferroelectric layers, have different hysteresis characteristics depending on the voltage. Specifically, when a high voltage is applied, the polarization becomes larger when the voltage becomes 0, and when a low voltage is applied, the polarization becomes smaller when the voltage becomes 0 compared to when a high voltage is applied. Therefore, as shown in Figure 7B, when the voltage V1 and the voltage V1-V TH Depending on the difference between the polarity difference (Δ) and the polarity difference (Δ) when the voltage becomes 0, the amount of charge held in the capacitors FC1 and FC2 can be made different depending on this polarity difference, so the output voltage V OUT1 and the output voltage V OUT2 As different values ​​of voltage V FE1 and voltage V FE2 can be output.

[0064] 8A and 8B illustrate a control circuit for a secondary battery to which the above-described semiconductor devices 100, 100A to 100E can be applied. The block diagram shown in Fig. 8A illustrates a secondary battery 110, a control circuit 120, a load 130, a charger 140, and a power transistor 150. Fig. 8A also illustrates a switch 131 for flowing current to the load 130 when the secondary battery 110 is discharged, and a switch 141 for flowing current from the charger 140 to charge the secondary battery 110. Fig. 8A also illustrates the terminals on the positive side of the load 130 and the charger 140 as VDDD and the terminals on the negative side as VSSS.

[0065] The control circuit 120 has a function of controlling the on / off of the power transistor 150 to prevent overcharging or over-discharging. The control circuit 120 may also be called a battery control circuit or a battery protection circuit. The control circuit 120 has a control unit 121 and a constant voltage generation unit 122. The semiconductor devices 100 and 100A to 100E described above can be used in the constant voltage generation unit 122.

[0066] The constant voltage generating unit 122 has semiconductor devices 100 and 100A to 100E that can output two voltages (voltage pairs) as multiple voltages. The voltages generated by providing multiple semiconductor devices that output voltage pairs can be used as reference voltages to prevent overcharging, overdischarging, etc. of secondary batteries such as lithium-ion batteries. In particular, the voltages obtained as the voltage pairs can be used as upper and lower limit voltages to determine overcharging, overdischarging, etc. of the secondary battery. The control circuit 120 compares the obtained upper and lower limit voltages with the voltage of the secondary battery and controls the power transistor 150.

[0067] Note that Fig. 8B shows a configuration in which the secondary battery is an assembled battery using multiple secondary batteries. In Fig. 8B, in addition to assembled battery 111 having secondary battery 110, there is also shown resistive element 151 that detects the current for charging secondary battery 110, and power transistors 150A and 150B that control charging or discharging. As shown in Fig. 8B, control circuit 120 is connected to terminals that detect the voltage, current, etc. of secondary battery 110. Control circuit 120 estimates the state of secondary battery 110 by processing the voltage, current, etc. of secondary battery 110 using analog circuits such as an internal comparison circuit and constant voltage generation circuit, and controls terminals that are connected to elements that control charging and discharging.

[0068] An example of the configuration of the control unit 121 and the constant voltage generating unit 122 included in the control circuit 120 will be described with reference to FIGS.

[0069] 9 is a block diagram illustrating an example of the configuration of the control circuit 120. The control unit 121 has a data generation unit 123 and a digital-to-analog conversion circuit 124. The data generation unit 123 generates data D IN Generate data D IN is digital data. The digital-to-analog conversion circuit 124 converts the data D IN The analog value of the input voltage V is IN It has the function to convert to.

[0070] The constant voltage generating unit 122 has, as an example, four semiconductor devices 100_1 to 100_4. The semiconductor devices 100 and 100A to 100E described above can be applied as the semiconductor devices 100_1 to 100_4. The semiconductor devices 100_1 to 100_4 are respectively given selection signals S1 to S4 and generate an input voltage V at a desired timing. IN is given.

[0071] The operation of the control circuit 120 in FIG. 9 will be described with reference to an example of a timing chart shown in FIG.

[0072] At time T11, the data generator 123 outputs data D IN_1 In a period T12, the selection signal S1 is set to an H level, so that the semiconductor device 100_1 generates an output voltage V based on the input voltage V1. OUT1 and the output voltage V OUT2 Generates an output voltage V OUT1 becomes voltage V1, and the output voltage V OUT1 is the threshold voltage V of the transistor M1 of the semiconductor device 100_1. TH The difference between the voltages V1-V TH This becomes:

[0073] Next, at time T21, the data generator 123 outputs data D IN_2In a period T22, the selection signal S2 is set to an H level, so that the semiconductor device 100_2 generates an output voltage V based on the input voltage V2. OUT3 and the output voltage V OUT4 Generates an output voltage V OUT3 becomes voltage V2, and the output voltage V OUT4 is the threshold voltage V of the transistor M1 of the semiconductor device 100_2. TH The difference between the voltages V2-V TH This becomes:

[0074] Next, at time T31, the data generator 123 outputs data D IN_3 In a period T32, the selection signal S3 is set to an H level, so that the semiconductor device 100_3 generates an output voltage V based on the input voltage V3. OUT5 and the output voltage V OUT6 Generates an output voltage V OUT5 becomes voltage V3, and the output voltage V OUT6 is the threshold voltage V of the transistor M1 of the semiconductor device 100_3. TH The difference between the voltages V3-V TH This becomes:

[0075] Next, at time T41, the data generator 123 outputs data D IN_4 In a period T42, the selection signal S4 is set to an H level, so that the semiconductor device 100_4 generates an output voltage V based on the input voltage V4. OUT7 and the output voltage V OUT8 Generates an output voltage V OUT7 becomes voltage V4, and the output voltage V OUT8 is the threshold voltage V of the transistor M1 of the semiconductor device 100_4. TH The difference between the voltages V4-V TH This becomes:

[0076] Here, even if the power supply of the digital-to-analog conversion circuit 124 is turned off after the input voltages V1 to V4 are supplied to the semiconductor devices 100_1 to 100_4, the semiconductor devices 100_1 to 100_4 continue to output the output voltages V OUT1 and the output voltage V OUT2 , output voltage V OUT3 and the output voltage V OUT4 , output voltage V OUT5 and the output voltage V OUT6 , output voltage V OUT7 and the output voltage V OUT8 In other words, power consumption can be reduced. In addition, a pair of reference voltages can be set simultaneously by supplying input voltages V1 to V4. In other words, the reference voltages can be set efficiently.

[0077] By adopting the above-described configuration, it is possible to provide a control circuit for a secondary battery that can reduce power consumption in the control circuit and easily set the comparison voltage.

[0078] As described above, each voltage pair can be used as an upper limit voltage and a lower limit voltage when performing trickle charging, for example. Each voltage pair is a voltage that is different from the input voltage V V supplied to the semiconductor devices 100_1 to 100_4. IN It is preferable to make the output voltage V OUT1 and the output voltage V OUT2 , output voltage V OUT3 and the output voltage V OUT4 , output voltage V OUT5 and the output voltage V OUT6 , output voltage V OUT7 and the output voltage V OUT8 , can be held at different voltages, and the voltage pair can be switched in response to changes in the environmental temperature.

[0079] 9 and 10, in order to prevent overcharging, charging is stopped when the secondary battery voltage exceeds the upper limit voltage for overcharging, and the next charging is permitted when the voltage falls below the lower limit voltage for overcharging. This makes it possible to switch the voltage for such operations using the input voltage and the threshold voltage of the transistor, thereby optimizing the on / off state of charging and reducing the burden on the secondary battery. Similarly, it is possible to optimize the on / off state of discharging and reduce the burden on the secondary battery.

[0080] In a control circuit for a secondary battery, the configuration for generating a reference voltage for voltage comparison is not limited to the configurations shown in Figures 1 to 10. An example of the configuration of a circuit for generating a reference voltage will be described with reference to Figures 11A and 11B.

[0081] Figure 11A shows the voltage V COMP and the reference voltage V generated by the reference voltage generator GEN. REF 1 shows a circuit diagram of a comparator COMP that receives and outputs a voltage VOUT according to the comparison result.

[0082] The reference voltage V shown in the circuit diagram in Figure 11A REF is supplied to the comparator COMP during comparison. REF The reference voltage generator GEN generates the voltage V COMP The reference voltage V REF Therefore, the reference voltage generating circuit GEN does not need to operate constantly, and therefore, a configuration can be achieved that achieves low power consumption.

[0083] An example of the configuration of the reference voltage generating circuit GEN is shown in FIG. 11B. The reference voltage generating circuit GEN is an analog amplifier circuit A. BUF , a transistor M11, a capacitor CF11, a capacitor C11, a capacitor C12, a drive circuit DR, and a sense amplifier SENCE.

[0084] Analog amplifier circuit A BUFcan be omitted. The transistor M11 is a Si transistor. The transistor M11 may be an OS transistor. The transistor M11 is turned on or off by the wiring WL.

[0085] The capacitor CF11 has a ferroelectric layer between a pair of electrodes. A capacitor with a ferroelectric layer has a property that polarization occurs inside when an electric field is applied from the outside, and the polarization remains even when the electric field is removed to zero (hysteresis characteristic). Therefore, the capacitance value of the capacitor CF11 can be set by setting the electrodes to a predetermined potential. The capacitance value of the capacitor CF11 is set by turning on the transistor M11 and applying a voltage V PL and the voltage provided by the drive circuit DR. The capacitance value of the capacitor CF11 is C FE It is expressed as:

[0086] The capacitor CF11 can hold a set capacitance value as an analog value. Therefore, an element formed by the transistor M11 and the capacitor CF11 can be used as an analog memory. Although the capacitor CF11 is described as an analog memory that holds analog values, it may also be configured as a digital memory that holds digital values. In this case, a plurality of capacitors CF11 can be provided, and the plurality of capacitors CF11 can be configured to be used as a weighted digital memory. Each digital memory can hold a polarization state corresponding to data 1 or 0. Alternatively, a digital-to-analog conversion circuit may be used to convert the data held in the digital memory into an analog value.

[0087] The capacitances C11 and C12 correspond to the capacitance of the input wiring of the sense amplifier SENCE. It is preferable to design the capacitances C11 and C12 to be the same. The capacitance values ​​of the capacitances C11 and C12 are C L The sense amplifier SENCE amplifies the potential difference between the input wirings and supplies it to the drive circuit DR.

[0088] Voltage V COMP The reference voltage V is generated at the timing of the comparison operation. REFis an analog amplifier circuit A BUF The voltage V of the wire connected to L Equivalent to voltage V L is the capacitance value C of capacitor CF11 FE , the capacitance value C of capacitors C11 and C12 L , voltage V PL and can be expressed by equation (1).

[0089]

number

[0090] From equation (1), the voltage generated by the reference voltage generation circuit GEN is determined by the capacitance value set in the capacitor CF11. COMP At the timing of the comparison operation of voltage V PL By setting and turning on transistor M11, the reference voltage V REF can be generated.

[0091] The structure described in this embodiment mode can be combined as appropriate with structures described in other embodiments.

[0092] (Embodiment 2) In this embodiment, a structural example of a transistor applicable to the semiconductor device functioning as a control circuit for the secondary battery described in the above embodiment will be described. As an example, a structure in which transistors having different electrical characteristics are stacked will be described. By using this structure, the degree of freedom in designing the semiconductor device can be increased. In addition, by stacking transistors having different electrical characteristics, the degree of integration of the semiconductor device can be increased.

[0093] <Configuration example of semiconductor device> 12 shows, as an example, the semiconductor device described in the above embodiment, which includes a transistor 300, a transistor 500, and a capacitor 600. Fig. 13A shows a cross-sectional view of the transistor 500 in the channel length direction, Fig. 13B shows a cross-sectional view of the transistor 500 in the channel width direction, and Fig. 13C shows a cross-sectional view of the transistor 300 in the channel width direction.

[0094] The transistor 500 is a transistor (OS transistor) having a metal oxide in a channel formation region. The transistor 500 has characteristics of a small off-state current and a field-effect mobility that does not change easily even at high temperatures. By applying the transistor 500 to a semiconductor device, such as the OS transistor described in the above embodiment, a semiconductor device whose operating capability is not easily degraded even at high temperatures can be realized.

[0095] The transistor 500 is provided above the transistor 300, for example, and the capacitor 600 is provided above the transistors 300 and 500, for example. Note that the capacitor 600 can be any of the capacitors described in the above embodiments.

[0096] The transistor 300 is provided over a substrate 310 and includes an element isolation layer 312, a conductor 316, an insulator 315, a semiconductor region 313 formed of part of the substrate 310, and low-resistance regions 314a and 314b functioning as source and drain regions. The transistor 300 can be applied to, for example, the Si transistor described in the above embodiment. As an example, FIG. 12 illustrates a configuration in which the gate of the transistor 300 is electrically connected to one of the source and drain of the transistor 500 via a pair of electrodes of a capacitor 600.

[0097] The substrate 310 is preferably a semiconductor substrate (for example, a single crystal substrate or a silicon substrate).

[0098] 13C , the upper surface and the side surfaces in the channel width direction of the semiconductor region 313 of the transistor 300 are covered with a conductor 316 via an insulator 315. By forming the transistor 300 as a fin type in this way, the effective channel width is increased, thereby improving the on-state characteristics of the transistor 300. Furthermore, the contribution of the electric field of the gate electrode can be increased, thereby improving the off-state characteristics of the transistor 300.

[0099] The transistor 300 may be either a p-channel type or an n-channel type.

[0100] The region where the channel of the semiconductor region 313 is formed, the region nearby, the low-resistance region 314a that serves as the source region or the drain region, and the low-resistance region 314b preferably contain a semiconductor such as a silicon-based semiconductor, and preferably contain single-crystal silicon. Alternatively, they may be formed of a material containing Ge (germanium), SiGe (silicon germanium), GaAs (gallium arsenide), GaAlAs (gallium aluminum arsenide), GaN (gallium nitride), or the like. A configuration using silicon in which the effective mass is controlled by applying stress to the crystal lattice and changing the lattice spacing may also be used. Alternatively, the transistor 300 may be a HEMT (High Electron Mobility Transistor) by using GaAs and GaAlAs, or the like.

[0101] The low resistance region 314a and the low resistance region 314b contain, in addition to the semiconductor material applied to the semiconductor region 313, an element that imparts n-type conductivity, such as arsenic or phosphorus, or an element that imparts p-type conductivity, such as boron.

[0102] The conductor 316 functioning as the gate electrode can be made of a conductive material such as a semiconductor material, metal material, alloy material, or metal oxide material, such as silicon containing an element that imparts n-type conductivity, such as arsenic or phosphorus, or an element that imparts p-type conductivity, such as boron.

[0103] 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 as 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 the conductor in a stacked structure, and tungsten is particularly preferable in terms of heat resistance.

[0104] The element isolation layer 312 is provided to isolate a plurality of transistors formed on the substrate 310. The element isolation layer can be formed by using, for example, a local oxidation of silicon (LOCOS) method, a shallow trench isolation (STI) method, a mesa isolation method, or the like.

[0105] The transistor 300 shown in FIG. 12 is just an example, and the structure is not limited thereto. An appropriate transistor may be used depending on the circuit configuration, driving method, and the like. For example, the transistor 300 may have a planar structure instead of the FIN structure shown in FIG. 13C. For example, when the semiconductor device is a unipolar circuit including only OS transistors, the structure of the transistor 300 may be the same as that of the transistor 500 including an oxide semiconductor, as shown in FIG. 14. The details of the transistor 500 will be described later. In this specification and the like, a unipolar circuit refers to a circuit including transistors of only one polarity, that is, an n-channel transistor or a p-channel transistor.

[0106] In FIG. 14, the transistor 300 is provided on a substrate 310A. However, in this case, the substrate 310A may be a semiconductor substrate similar to the substrate 310 of the semiconductor device in FIG. 12. The substrate 310A may be, for example, an SOI substrate, a glass substrate, a quartz substrate, a plastic substrate, a sapphire glass substrate, a metal substrate, a stainless steel substrate, a substrate having stainless steel foil, a tungsten substrate, a substrate having tungsten foil, a flexible substrate, a laminated film, paper containing a fibrous material, or a base film. Examples of glass substrates include barium borosilicate glass, aluminoborosilicate glass, and soda-lime glass. Examples of flexible substrates, laminated films, and base films include the following: Plastics such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethersulfone (PES), and polytetrafluoroethylene (PTFE). Another example is a synthetic resin such as acrylic. Examples of the material include polypropylene, polyester, polyvinyl fluoride, and polyvinyl chloride, as well as polyamide, polyimide, aramid, epoxy resin, inorganic vapor deposition film, and paper.

[0107] In the transistor 300 shown in FIG. 12, an insulator 320, an insulator 322, an insulator 324, and an insulator 326 are stacked in this order from the substrate 310 side.

[0108] The insulators 320, 322, 324, and 326 can be formed using, for example, silicon oxide, silicon oxynitride, silicon nitride oxide, silicon nitride, aluminum oxide, aluminum oxynitride, aluminum nitride oxide, aluminum nitride, or the like.

[0109] In this specification, silicon oxynitride refers to a material whose composition contains more oxygen than nitrogen, silicon nitride oxide refers to a material whose composition contains more nitrogen than oxygen, aluminum oxynitride refers to a material whose composition contains more oxygen than nitrogen, and aluminum nitride oxide refers to a material whose composition contains more nitrogen than oxygen.

[0110] The insulator 322 may function as a planarizing film that flattens steps caused by the insulator 320 and the transistor 300 covered by the insulator 322. For example, the top surface of the insulator 322 may be planarized by planarization treatment using a chemical mechanical polishing (CMP) method or the like to improve flatness.

[0111] The insulator 324 is preferably a film having a barrier property that prevents hydrogen, impurities, and the like from diffusing from the substrate 310 or the transistor 300 to a region where the transistor 500 is provided.

[0112] An example of a film having a barrier property against hydrogen is silicon nitride formed by a CVD method. Here, hydrogen diffusion into a semiconductor element having an oxide semiconductor, such as the transistor 500, may degrade the characteristics of the semiconductor element. Therefore, it is preferable to use a film that suppresses hydrogen diffusion between the transistor 500 and the transistor 300. Specifically, the film that suppresses hydrogen diffusion is a film that releases a small amount of hydrogen.

[0113] The amount of desorption of hydrogen can be analyzed using, for example, thermal desorption spectroscopy (TDS). For example, the amount of desorption of hydrogen from the insulator 324 is calculated as 10×10 per area of ​​the insulator 324 when the surface temperature of the film is in the range of 50° C. to 500° C. in TDS analysis. 15 atoms / cm 2 Less than or equal to 5 x 10 15atoms / cm 2 The following is fine.

[0114] It is preferable that the insulator 326 has a lower dielectric constant than the insulator 324. For example, the relative dielectric constant of the insulator 326 is preferably less than 4, and more preferably less than 3. Furthermore, for example, the relative dielectric constant of the insulator 326 is preferably 0.7 times or less, and more preferably 0.6 times or less, the relative dielectric constant of the insulator 324. By using a material with a low dielectric constant as the interlayer film, the parasitic capacitance that occurs between wirings can be reduced.

[0115] Furthermore, the insulators 320, 322, 324, and 326 are embedded with the capacitor 600 or the conductors 328 and 330 connected to the transistor 500. The conductors 328 and 330 function as plugs or wiring. Furthermore, for conductors that function as plugs or wiring, the same reference numeral may be used to denote multiple structures. Furthermore, in this specification and the like, the wiring and the plug connected to the wiring may be integrated. That is, there are cases where a part of the conductor functions as the wiring, and cases where a part of the conductor functions as the plug.

[0116] The materials for each plug and wiring (conductor 328, conductor 330, etc.) can be a conductive material such as a metal material, an alloy material, a metal nitride material, or a metal oxide material, and can be used in a single layer or a stacked layer. It is preferable to use a high-melting-point material such as tungsten or molybdenum that has both heat resistance and conductivity, and tungsten is preferred. Alternatively, it is preferable to form the wiring from a low-resistance conductive material such as aluminum or copper. Using a low-resistance conductive material can reduce the wiring resistance.

[0117] A wiring layer may be provided over the insulator 326 and the conductor 330. For example, in FIG. 12 , the insulator 350, the insulator 352, and the insulator 354 are stacked in this order over the insulator 326 and the conductor 330. The conductor 356 is formed in the insulator 350, the insulator 352, and the insulator 354. The conductor 356 functions as a plug or wiring connected to the transistor 300. Note that the conductor 356 can be formed using a material similar to that of the conductor 328 and the conductor 330.

[0118] Note that, for example, the insulator 350 is preferably an insulator having barrier properties against impurities such as hydrogen and water, similar to the insulator 324. Similarly to the insulator 326, the insulators 352 and 354 are preferably insulators having a relatively low dielectric constant in order to reduce parasitic capacitance between wirings. The conductor 356 preferably includes a conductor having barrier properties against impurities such as hydrogen and water. In particular, a conductor having barrier properties against hydrogen is formed in the opening of the insulator 350 having barrier properties against hydrogen. With this structure, the transistor 300 and the transistor 500 can be separated by a barrier layer, thereby suppressing diffusion of hydrogen from the transistor 300 to the transistor 500.

[0119] Note that, for example, tantalum nitride or the like is preferably used as the conductor having a barrier property against hydrogen. Stacking tantalum nitride and highly conductive tungsten can suppress diffusion of hydrogen from the transistor 300 while maintaining the conductivity of the wiring. In this case, a structure in which the tantalum nitride layer having a barrier property against hydrogen is in contact with the insulator 350 having a barrier property against hydrogen is preferable.

[0120] Furthermore, on the insulator 354 and the conductor 356, an insulator 360, an insulator 362, and an insulator 364 are stacked in this order.

[0121] The insulator 360 is preferably an insulator having barrier properties against impurities such as water and hydrogen, similar to the insulator 324. Therefore, the insulator 360 can be made of, for example, a material that can be used for the insulator 324.

[0122] The insulators 362 and 364 function as an interlayer insulating film and a planarizing film. As the insulators 362 and 364, it is preferable to use an insulator that has a barrier property against impurities such as water and hydrogen, similar to the insulator 324. Therefore, the insulator 362 and / or the insulator 364 can be made of a material that can be used for the insulator 324.

[0123] Openings are formed in the insulators 360, 362, and 364 in regions that overlap with part of the conductor 356, and the conductor 366 is provided to fill the openings. The conductor 366 is also formed over the insulator 362. For example, the conductor 366 functions as a plug or a wiring connected to the transistor 300. Note that the conductor 366 can be formed using a material similar to that of the conductors 328 and 330.

[0124] An insulator 510, an insulator 512, an insulator 514, and an insulator 516 are stacked in this order over the insulator 364 and the conductor 366. Any of the insulator 510, the insulator 512, the insulator 514, and the insulator 516 is preferably made using a substance that has a barrier property against oxygen and hydrogen.

[0125] For example, the insulator 510 and the insulator 514 are preferably formed using a film having a barrier property that prevents hydrogen and impurities from diffusing from the substrate 310 or the region where the transistor 300 is provided to the region where the transistor 500 is provided. Therefore, a material similar to that of the insulator 324 can be used.

[0126] An example of a film having a barrier property against hydrogen is silicon nitride formed by a CVD method. Here, hydrogen diffusion into a semiconductor element having an oxide semiconductor, such as the transistor 500, may degrade the characteristics of the semiconductor element. Therefore, it is preferable to use a film that suppresses hydrogen diffusion between the transistor 500 and the transistor 300. Specifically, the film that suppresses hydrogen diffusion is a film that releases a small amount of hydrogen.

[0127] As a film having a barrier property against hydrogen, for example, the insulators 510 and 514 are preferably made of a metal oxide such as aluminum oxide, hafnium oxide, or tantalum oxide.

[0128] In particular, aluminum oxide has a high blocking effect of preventing the permeation of both oxygen and impurities such as hydrogen and moisture, which can cause fluctuations in the electrical characteristics of a transistor. Therefore, aluminum oxide can prevent impurities such as hydrogen and moisture from entering the transistor 500 during and after the transistor manufacturing process. Furthermore, aluminum oxide can suppress the release of oxygen from the oxide that constitutes the transistor 500. Therefore, aluminum oxide is suitable for use as a protective film for the transistor 500.

[0129] For example, the insulator 512 and the insulator 516 can be formed using a material similar to that of the insulator 320. By using a material with a relatively low dielectric constant for these insulators, parasitic capacitance 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.

[0130] A conductor 518, a conductor constituting the transistor 500 (for example, the conductor 503 shown in FIGS. 13A and 13B), and the like are embedded in the insulators 510, 512, 514, and 516. The conductor 518 functions as a capacitor 600 or a plug or wiring connected to the transistor 300. The conductor 518 can be formed using a material similar to that of the conductors 328 and 330.

[0131] In particular, the conductor 518 in the region in contact with the insulator 510 and the insulator 514 is preferably a conductor that has a barrier property against oxygen, hydrogen, and water. With this structure, the transistor 300 and the transistor 500 can be separated by a layer that has a barrier property against oxygen, hydrogen, and water, and diffusion of hydrogen from the transistor 300 to the transistor 500 can be suppressed.

[0132] Above the insulator 516 is the transistor 500 .

[0133] As shown in FIGS. 13A and 13B, the transistor 500 includes an insulator 516 on an insulator 514, a conductor 503 (conductors 503a and 503b) disposed so as to be embedded in the insulator 514 or the insulator 516, an insulator 522 on the insulator 516 and on the conductor 503, an insulator 524 on the insulator 522, an oxide 530a on the insulator 524, an oxide 530b on the oxide 530a, a conductor 542a on the oxide 530b, an insulator 571a on the conductor 542a, and an oxide 572a on the oxide 572b. conductor 542b on oxide 530b, insulator 571b on conductor 542b, insulator 552 on oxide 530b, insulator 550 on insulator 552, insulator 554 on insulator 550, conductor 560 (conductor 560a and conductor 560b) located on insulator 554 and overlapping part of oxide 530b, and insulator 544 arranged on insulator 522, insulator 524, oxide 530a, oxide 530b, conductor 542a, conductor 542b, insulator 571a, and insulator 571b. 13A and 13B, insulator 552 contacts the upper surface of insulator 522, the side surface of insulator 524, the side surface of oxide 530a, the side surface and upper surface of oxide 530b, the side surface of conductor 542 (conductor 542a and conductor 542b), the side surface of insulator 571 (insulator 571a and insulator 571b), the side surface of insulator 544, the side surface of insulator 580, and the lower surface of insulator 550. The upper surface of conductor 560 is disposed so as to be at approximately the same height as the upper surfaces of insulator 554, insulator 550, insulator 552, and insulator 580. Insulator 574 contacts at least a portion of the upper surface of conductor 560, insulator 552, insulator 550, insulator 554, and insulator 580.

[0134] Openings reaching the oxide 530b are provided in the insulator 580 and the insulator 544. The insulator 552, the insulator 550, the insulator 554, and the conductor 560 are disposed in the openings. In addition, the conductor 560, the insulator 552, the insulator 550, and the insulator 554 are provided between the insulator 571a and the conductor 542a and between the insulator 571b and the conductor 542b in the channel length direction of the transistor 500. The insulator 554 has a region in contact with the side surface of the conductor 560 and a region in contact with the bottom surface of the conductor 560.

[0135] The oxide 530 preferably includes an oxide 530a disposed on the insulator 524 and an oxide 530b disposed on the oxide 530a. By providing the oxide 530a below the oxide 530b, it is possible to suppress the diffusion of impurities from structures formed below the oxide 530a to the oxide 530b.

[0136] Note that although the transistor 500 has a structure in which the oxide 530 has two layers, the oxide 530a and the oxide 530b, the present invention is not limited to this. For example, the transistor 500 can have a single layer of the oxide 530b or a stacked structure of three or more layers. Alternatively, each of the oxide 530a and the oxide 530b can have a stacked structure.

[0137] The conductor 560 functions as a first gate (also referred to as a top gate) electrode, and the conductor 503 functions as a second gate (also referred to as a back gate) electrode. The insulators 552, 550, and 554 function as a first gate insulator, and the insulators 522 and 524 function as a second gate insulator. The gate insulators may also be referred to as a gate insulating layer or a gate insulating film. The conductor 542a functions as either a source or a drain, and the conductor 542b functions as the other. At least a part of a region of the oxide 530 that overlaps with the conductor 560 functions as a channel formation region.

[0138] FIG. 15A shows an enlarged view of the vicinity of the channel formation region in FIG. 13A. When oxygen is supplied to the oxide 530b, a channel formation region is formed in the region between the conductor 542a and the conductor 542b. Therefore, as shown in FIG. 15A, the oxide 530b includes a region 530bc that functions as the channel formation region of the transistor 500, and regions 530ba and 530bb that are provided on either side of the region 530bc and function as source and drain regions. At least a portion of the region 530bc overlaps with the conductor 560. In other words, the region 530bc is located in the region between the conductor 542a and the conductor 542b. The region 530ba overlaps with the conductor 542a, and the region 530bb overlaps with the conductor 542b.

[0139] The region 530bc, which functions as a channel formation region, has a smaller oxygen vacancy (in this specification, oxygen vacancy in a metal oxide is referred to as V) than the regions 530ba and 530bb. O The region 530bc is a high-resistance region with a low carrier concentration due to its low oxygen vacancy or low impurity concentration. Therefore, the region 530bc can be said to be i-type (intrinsic) or substantially i-type.

[0140] A transistor using a metal oxide has impurities or oxygen vacancies (V O ) may cause fluctuations in electrical characteristics and reduce reliability. O ) hydrogen near the oxygen vacancy (V O ) with hydrogen (hereafter referred to as V O H.) and generate electrons that serve as carriers. Therefore, if oxygen vacancies are present in the region where a channel is formed in the oxide semiconductor, the transistor is likely to have normally-on characteristics (a channel exists and current flows through the transistor even when no voltage is applied to the gate electrode). Therefore, in the region where a channel is formed in the oxide semiconductor, impurities, oxygen vacancies, and V OIt is preferable that H is reduced as much as possible.

[0141] The regions 530ba and 530bb that function as source and drain regions have oxygen vacancies (V O ) or high concentrations of impurities such as hydrogen, nitrogen, and metal elements, resulting in an increased carrier concentration and low resistance. That is, the regions 530ba and 530bb are n-type regions with a higher carrier concentration and lower resistance than the region 530bc.

[0142] Here, the carrier concentration of the region 530bc that functions as a channel forming region is 1×10 18 cm -3 Preferably, it is 1×10 or less. 17 cm -3 More preferably, it is less than 1×10 16 cm -3 More preferably, it is less than 1×10 13 cm -3 More preferably, it is less than 1×10 12 cm -3 The lower limit of the carrier concentration of the region 530bc that functions as a channel formation region is not particularly limited, but is preferably, for example, 1×10 -9 cm -3 It can be said that:

[0143] A region having a carrier concentration equal to or lower than that of regions 530ba and 530bb and equal to or higher than that of region 530bc may be formed between region 530bc and regions 530ba or 530bb. That is, this region functions as a junction region between region 530bc and regions 530ba or 530bb. The junction region may have a hydrogen concentration equal to or lower than that of regions 530ba and 530bb and equal to or higher than that of region 530bc. The junction region may also have oxygen vacancies equal to or lower than those of regions 530ba and 530bb and equal to or higher than those of region 530bc.

[0144] 15A illustrates an example in which the regions 530ba, 530bb, and 530bc are formed in the oxide 530b, but the present invention is not limited to this. For example, each of the regions may be formed not only in the oxide 530b but also in the oxide 530a.

[0145] Furthermore, it may be difficult to clearly detect the boundaries between the regions in the oxide 530. The concentrations of metal elements and impurity elements such as hydrogen and nitrogen detected in each region may vary continuously within each region, rather than gradually varying from region to region. In other words, it is sufficient that the concentrations of metal elements and impurity elements such as hydrogen and nitrogen decrease in the region closer to the channel formation region.

[0146] In the transistor 500, the oxide 530 including the channel formation region (the oxide 530a and the oxide 530b) is preferably a metal oxide that functions as a semiconductor (hereinafter also referred to as an oxide semiconductor).

[0147] The metal oxide functioning as a semiconductor preferably has a band gap of 2 eV or more, preferably 2.5 eV or more. By using such a metal oxide with a wide band gap, the off-state current of the transistor can be reduced.

[0148] For example, a metal oxide such as In-M-Zn oxide containing indium, element M, and zinc (element M is one or more elements selected from aluminum, gallium, yttrium, tin, copper, vanadium, beryllium, boron, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, magnesium, etc.) may be used as oxide 530. Alternatively, In-Ga oxide, In-Zn oxide, or indium oxide may be used as oxide 530.

[0149] Here, it is preferable that the atomic ratio of In to element M in the metal oxide used for oxide 530b is greater than the atomic ratio of In to element M in the metal oxide used for oxide 530a.

[0150] In this way, by disposing the oxide 530a below the oxide 530b, it is possible to suppress the diffusion of impurities and oxygen from the structure formed below the oxide 530a into the oxide 530b.

[0151] Furthermore, since the oxide 530a and the oxide 530b have a common element other than oxygen (as a main component), the defect state density at the interface between the oxide 530a and the oxide 530b can be reduced. Because the defect state density at the interface between the oxide 530a and the oxide 530b can be reduced, the effect of interface scattering on carrier conduction is reduced, and a high on-current can be obtained.

[0152] The oxide 530b preferably has crystallinity, and in particular, it is preferable to use c-axis aligned crystalline oxide semiconductor (CAAC-OS) as the oxide 530b.

[0153] CAAC-OS has a highly crystalline and dense structure, and is free of impurities and defects (e.g., oxygen vacancies (V O In particular, the CAAC-OS can be made to have a dense structure with higher crystallinity by heat-treating the formed metal oxide at a temperature (for example, 400°C or higher and 600°C or lower) at which the metal oxide does not polycrystallize. In this way, the density of the CAAC-OS can be increased, thereby further reducing the diffusion of impurities or oxygen in the CAAC-OS.

[0154] On the other hand, since it is difficult to identify clear grain boundaries in CAAC-OS, it is said that the decrease in electron mobility due to grain boundaries is unlikely to occur. Therefore, metal oxides with CAAC-OS have stable physical properties. As a result, metal oxides with CAAC-OS are heat-resistant and highly reliable.

[0155] In a transistor using an oxide semiconductor, if impurities and oxygen vacancies exist in a region where a channel is formed in the oxide semiconductor, the electrical characteristics are likely to fluctuate and the reliability may be reduced. In addition, hydrogen in the vicinity of the oxygen vacancy is converted into a defect where hydrogen enters the oxygen vacancy (hereinafter referred to as V O H.) and generate electrons that serve as carriers. Therefore, if oxygen vacancies are present in the region where a channel is formed in an oxide semiconductor, the transistor is likely to have normally-on characteristics (a channel exists and current flows through the transistor even when no voltage is applied to the gate electrode). Therefore, in the region where a channel is formed in an oxide semiconductor, impurities, oxygen vacancies, and V O It is preferable that H is reduced as much as possible. In other words, it is preferable that the region in the oxide semiconductor where a channel is formed has a reduced carrier concentration and is i-type (intrinsic) or substantially i-type.

[0156] In response to this problem, an insulator containing oxygen that is released by heating (hereinafter may be referred to as excess oxygen) is provided near the oxide semiconductor, and heat treatment is performed to supply oxygen from the insulator to the oxide semiconductor, thereby eliminating oxygen vacancies and V O H can be reduced. However, if an excessive amount of oxygen is supplied to the source region or the drain region, this may cause a decrease in the on-state current or a decrease in the field-effect mobility of the transistor 500. Furthermore, if the oxygen supplied to the source region or the drain region varies within the substrate plane, the characteristics of the semiconductor device having the transistor will vary.

[0157] Therefore, in the oxide semiconductor, the region 530bc that functions as a channel formation region preferably has a reduced carrier concentration and is i-type or substantially i-type, whereas the regions 530ba and 530bb that function as source and drain regions preferably have a high carrier concentration and are n-type. O It is preferable to reduce H so that an excessive amount of oxygen is not supplied to the regions 530ba and 530bb.

[0158] Therefore, in this embodiment, in a state where the conductors 542a and 542b are provided on the oxide 530b, microwave treatment is performed in an atmosphere containing oxygen to remove oxygen vacancies in the region 530bc and V O The microwave treatment here refers to a treatment using a device with a power source that generates high-density plasma using microwaves, for example.

[0159] By performing microwave processing in an atmosphere containing oxygen, oxygen gas can be converted into plasma using microwaves or high frequency waves such as RF, and the oxygen plasma can be activated. At this time, microwaves or high frequency waves such as RF can also be irradiated onto the region 530bc. The V of the region 530bc can be activated by the action of the plasma, microwaves, etc. O H is split off, hydrogen H is removed from the region 530bc, and oxygen vacancy V Ocan be compensated with oxygen. O H → H + V O This reaction occurs, and the hydrogen concentration in the region 530bc can be reduced. O H can be reduced to lower the carrier concentration.

[0160] Furthermore, when microwave processing is performed in an atmosphere containing oxygen, the effects of microwaves, high frequency waves such as RF, oxygen plasma, etc. are shielded by the conductors 542a and 542b and do not reach the regions 530ba and 530bb. Furthermore, the effects of oxygen plasma can be reduced by the insulators 571 and 580 that cover the oxide 530b and the conductor 542. As a result, during microwave processing, V O Since there is no reduction in H and no excessive supply of oxygen, it is possible to prevent a decrease in the carrier concentration.

[0161] Furthermore, it is preferable to perform microwave treatment in an oxygen-containing atmosphere after forming the insulating film that becomes the insulator 552 or after forming the insulating film that becomes the insulator 550. By performing microwave treatment in an oxygen-containing atmosphere through the insulator 552 or the insulator 550 in this manner, oxygen can be efficiently injected into the region 530bc. Furthermore, by arranging the insulator 552 so as to be in contact with the side surface of the conductor 542 and the surface of the region 530bc, injection of more oxygen than necessary into the region 530bc can be suppressed, thereby suppressing oxidation of the side surface of the conductor 542. Furthermore, oxidation of the side surface of the conductor 542 can be suppressed during formation of the insulating film that becomes the insulator 550.

[0162] The oxygen implanted into the region 530bc can be in various forms, such as oxygen atoms, oxygen molecules, or oxygen radicals (atoms, molecules, or ions with an unpaired electron, also known as O radicals). The oxygen implanted into the region 530bc preferably takes one or more of the above forms, and oxygen radicals are particularly preferred. This can improve the film quality of the insulators 552 and 550, thereby improving the reliability of the transistor 500.

[0163] In this way, oxygen vacancies and V are selectively formed in the oxide semiconductor region 530bc. O By removing H, the region 530bc can be made i-type or substantially i-type. Furthermore, the supply of excess oxygen to the regions 530ba and 530bb, which function as source and drain regions, can be prevented, maintaining n-type conductivity. This suppresses fluctuations in the electrical characteristics of the transistor 500, thereby reducing variations in the electrical characteristics of the transistor 500 within the substrate surface.

[0164] By adopting the above-described configuration, it is possible to provide a semiconductor device with less variation in transistor characteristics, a highly reliable semiconductor device, and a semiconductor device with good electrical characteristics.

[0165] 13B, in a cross-sectional view of the transistor 500 in the channel width direction, a curved surface may be formed between the side surface of the oxide 530b and the top surface of the oxide 530b. That is, the end portions of the side surface and the top surface may be curved (hereinafter also referred to as rounded).

[0166] The radius of curvature of the curved surface is preferably greater than 0 nm and smaller than the film thickness of the oxide 530b in the region overlapping with the conductor 542, or smaller than half the length of the region not having the curved surface. Specifically, the radius of curvature of the curved surface is greater than 0 nm and smaller than 20 nm, preferably greater than 1 nm and smaller than 15 nm, and more preferably greater than 2 nm and smaller than 10 nm. This shape can improve the coverage of the oxide 530b with the insulators 552, 550, and 554, and the conductor 560.

[0167] The oxide 530 preferably has a stacked structure of multiple oxide layers with different chemical compositions. Specifically, in the metal oxide used for the oxide 530a, the atomic ratio of the element M to the metal element that is the main component is preferably greater than the atomic ratio of the element M to the metal element that is the main component in the metal oxide used for the oxide 530b. Furthermore, in the metal oxide used for the oxide 530a, the atomic ratio of the element M to In is preferably greater than the atomic ratio of the element M to In in the metal oxide used for the oxide 530b. Furthermore, in the metal oxide used for the oxide 530b, the atomic ratio of In to the element M is preferably greater than the atomic ratio of In to the element M in the metal oxide used for the oxide 530a.

[0168] The oxide 530b is preferably a crystalline oxide such as CAAC-OS. Crystalline oxides such as CAAC-OS have few impurities and defects (such as oxygen vacancies), and have a highly crystalline and dense structure. This can prevent the source or drain electrode from extracting oxygen from the oxide 530b. This can reduce the extraction of oxygen from the oxide 530b even during heat treatment, making the transistor 500 stable against high temperatures (so-called thermal budget) in the manufacturing process.

[0169] Here, the conduction band minimum changes gradually at the junction between the oxides 530a and 530b. In other words, the conduction band minimum at the junction between the oxides 530a and 530b changes continuously or forms a continuous junction. To achieve this, it is advisable to reduce the defect level density of the mixed layer formed at the interface between the oxides 530a and 530b.

[0170] Specifically, when the oxide 530a and the oxide 530b contain a common element other than oxygen as a main component, a mixed layer with a low density of defect states can be formed. For example, when the oxide 530b is an In-M-Zn oxide, the oxide 530a may be an In-M-Zn oxide, an M-Zn oxide, an oxide of element M, an In-Zn oxide, an indium oxide, or the like.

[0171] Specifically, oxide 530a may be a metal oxide having an atomic ratio of In:M:Zn=1:3:4 or a similar composition, or an atomic ratio of In:M:Zn=1:1:0.5 or a similar composition. Oxide 530b may be a metal oxide having an atomic ratio of In:M:Zn=1:1:1 or a similar composition, or an atomic ratio of In:M:Zn=4:2:3 or a similar composition. Note that a similar composition includes a range of ±30% of the desired atomic ratio. Gallium is preferably used as element M.

[0172] When a metal oxide film is formed by sputtering, the atomic ratio is not limited to the atomic ratio of the formed metal oxide film, but may be the atomic ratio of a sputtering target used to form the metal oxide film.

[0173] 13A and other figures, providing an insulator 552 made of aluminum oxide or the like in contact with the top and side surfaces of the oxide 530 can cause indium in the oxide 530 to be unevenly distributed at and near the interface between the oxide 530 and the insulator 552. This results in an atomic ratio near the surface of the oxide 530 that is close to that of indium oxide or In-Zn oxide. The increased atomic ratio of indium near the surface of the oxide 530, particularly the oxide 530b, can improve the field-effect mobility of the transistor 500.

[0174] The oxide 530a and the oxide 530b have the above-described structure, which can reduce the defect state density at the interface between the oxide 530a and the oxide 530b. As a result, the influence of interface scattering on carrier conduction is reduced, and the transistor 500 can achieve a large on-state current and high frequency characteristics.

[0175] At least one of the insulators 512, 514, 544, 571, 574, 576, and 581 preferably functions as a barrier insulating film that suppresses diffusion of impurities such as water and hydrogen from the substrate side or from above the transistor 500 into the transistor 500. Therefore, at least one of the insulators 512, 514, 544, 571, 574, 576, and 581 is preferably made of an insulating material that suppresses diffusion of impurities such as hydrogen atoms, hydrogen molecules, water molecules, nitrogen atoms, nitrogen molecules, nitrogen oxide molecules (such as NO, NO, and NO), and copper atoms (i.e., through which the above impurities are less likely to permeate). Alternatively, it is preferably made of an insulating material that suppresses diffusion of oxygen (e.g., at least one of oxygen atoms and oxygen molecules) (i.e., through which the above oxygen is less likely to permeate).

[0176] In this specification, a barrier insulating film refers to an insulating film having barrier properties. In this specification, the barrier properties refer to a function of suppressing the diffusion of a corresponding substance (also referred to as low permeability) or a function of capturing and fixing a corresponding substance (also referred to as gettering).

[0177] For the insulators 512, 514, 544, 571, 574, 576, and 581, it is preferable to use an insulator that has the function of suppressing diffusion of impurities such as water and hydrogen and oxygen. For example, aluminum oxide, magnesium oxide, hafnium oxide, gallium oxide, indium gallium zinc oxide, silicon nitride, or silicon nitride oxide can be used. For example, silicon nitride, which has a high hydrogen barrier property, is preferably used for the insulators 512, 544, and 576. Furthermore, for example, it is preferable to use aluminum oxide or magnesium oxide, which has the function of capturing and fixing hydrogen, for the insulators 514, 571, 574, and 581. This can suppress diffusion of impurities such as water and hydrogen from the substrate side to the transistor 500 side through the insulators 512 and 514. Alternatively, impurities such as water and hydrogen can be prevented from diffusing toward the transistor 500 from an interlayer insulating film disposed outside the insulator 581. Alternatively, oxygen contained in the insulator 524 and the like can be prevented from diffusing toward the substrate through the insulators 512 and 514. Alternatively, oxygen contained in the insulator 580 and the like can be prevented from diffusing upward from the transistor 500 through the insulator 574. In this way, the transistor 500 is preferably surrounded by the insulators 512, 514, 571, 544, 574, 576, and 581, which have the function of preventing the diffusion of impurities such as water and hydrogen and oxygen.

[0178] Here, it is preferable to use an oxide having an amorphous structure as the insulators 512, 514, 544, 571, 574, 576, and 581. For example, AlO x (x is any number greater than 0), or MgO y It is preferable to use a metal oxide such as y (where y is any number greater than 0). In such metal oxides having an amorphous structure, oxygen atoms have dangling bonds, and the dangling bonds may have the property of capturing or fixing hydrogen. By using such a metal oxide having an amorphous structure as a component of the transistor 500 or providing it around the transistor 500, hydrogen contained in the transistor 500 or hydrogen present around the transistor 500 can be captured or fixed. In particular, it is preferable to capture or fix hydrogen contained in the channel formation region of the transistor 500. By using a metal oxide having an amorphous structure as a component of the transistor 500 or providing it around the transistor 500, a highly reliable transistor 500 and semiconductor device can be manufactured with excellent characteristics.

[0179] Furthermore, the insulators 512, 514, 544, 571, 574, 576, and 581 preferably have an amorphous structure, but may have a polycrystalline structure in part. The insulators 512, 514, 544, 571, 574, 576, and 581 may have a multilayer structure in which an amorphous layer and a polycrystalline layer are stacked. For example, they may have a stacked structure in which a polycrystalline layer is formed on an amorphous layer.

[0180] The insulators 512, 514, 544, 571, 574, 576, and 581 can be formed by, for example, a sputtering method. Sputtering does not require the use of hydrogen-containing molecules in a film formation gas, and therefore can reduce the hydrogen concentrations of the insulators 512, 514, 544, 571, 574, 576, and 581. Note that the film formation method is not limited to sputtering, and a chemical vapor deposition (CVD) method, a molecular beam epitaxy (MBE) method, a pulsed laser deposition (PLD) method, an atomic layer deposition (ALD) method, or the like may also be used as appropriate.

[0181] It may also be desirable to reduce the resistivity of insulators 512, 544, and 576. For example, it may be desirable to reduce the resistivity of insulators 512, 544, and 576 to approximately 1×10 13 By setting the resistivity to Ωcm, the insulators 512, 544, and 576 may be able to reduce charge-up of the conductors 503, 542, and 560 during treatment using plasma or the like in the manufacturing process of a semiconductor device. The resistivity of the insulators 512, 544, and 576 is preferably 1×10 10 Ωcm or more 1×10 15 Ωcm or less.

[0182] The insulators 516, 574, 580, and 581 preferably have a lower dielectric constant than the insulator 514. Using a material with a low dielectric constant as an interlayer film can reduce parasitic capacitance between wirings. For example, silicon oxide, silicon oxynitride, 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 the like can be used as appropriate for the insulators 516, 580, and 581.

[0183] For example, the insulator 581 is preferably an insulator that functions as an interlayer film, a planarizing film, or the like.

[0184] The conductor 503 is arranged to overlap the oxide 530 and the conductor 560. Here, the conductor 503 is preferably provided by being embedded in an opening formed in the insulator 516. In addition, a part of the conductor 503 may be embedded in the insulator 514.

[0185] The conductor 503 includes a conductor 503a and a conductor 503b. The conductor 503a is provided in contact with the bottom surface and sidewall of the opening. The conductor 503b is provided so as to be embedded in a recess formed in the conductor 503a. Here, the height of the top of the conductor 503b is approximately the same as the height of the top of the conductor 503a and the height of the top of the insulator 516.

[0186] Here, the conductor 503a is preferably made of a conductive material that has the function of suppressing the diffusion of impurities such as hydrogen atoms, hydrogen molecules, water molecules, nitrogen atoms, nitrogen molecules, nitrogen oxide molecules (NO, NO, NO, etc.), copper atoms, etc. Alternatively, it is preferably made of a conductive material that has the function of suppressing the diffusion of oxygen (for example, at least one of oxygen atoms, oxygen molecules, etc.).

[0187] By using a conductive material that can reduce hydrogen diffusion for the conductor 503a, it is possible to prevent impurities such as hydrogen contained in the conductor 503b from diffusing into the oxide 530 via the insulator 524 or the like. Furthermore, by using a conductive material that can suppress oxygen diffusion for the conductor 503a, it is possible to prevent the conductor 503b from being oxidized and its conductivity from decreasing. Examples of conductive materials that can suppress oxygen diffusion include titanium, titanium nitride, tantalum, tantalum nitride, ruthenium, and ruthenium oxide. Therefore, the conductor 503a may be a single layer or a multilayer of the above conductive materials. For example, the conductor 503a may be made of titanium nitride.

[0188] The conductor 503b is preferably made of a conductive material containing tungsten, copper, or aluminum as a main component, for example, tungsten.

[0189] The conductor 503 may function as a second gate electrode. In this case, the threshold voltage (Vth) 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, applying a negative potential to the conductor 503 can increase the Vth of the transistor 500 and reduce its off-state current. Therefore, applying a negative potential to the conductor 503 can reduce the drain current when the potential applied to the conductor 560 is 0 V compared to not applying a negative potential to the conductor 503.

[0190] The electrical resistivity of the conductor 503 is designed taking into consideration the potential applied to the conductor 503, and the film thickness of the conductor 503 is set to match this electrical resistivity. The film thickness of the insulator 516 is approximately the same as that of the conductor 503. Here, it is preferable to make the film thicknesses of the conductor 503 and the insulator 516 as thin as possible within the range permitted by the design of the conductor 503. By making the film thickness of the insulator 516 thin, the absolute amount of impurities such as hydrogen contained in the insulator 516 can be reduced, thereby reducing the diffusion of the impurities into the oxide 530.

[0191] Note that the conductor 503 is preferably larger than the area of ​​the oxide 530 that does not overlap with the conductors 542a and 542b when viewed from above. In particular, as shown in FIG. 13B , the conductor 503 preferably extends to an area outside the channel width direction ends of the oxides 530a and 530b. That is, outside the side surfaces of the oxide 530 in the channel width direction, the conductor 503 and the conductor 560 preferably overlap with each other via an insulator. With this structure, the channel formation region of the oxide 530 can be electrically surrounded by the electric field of the conductor 560, which functions as the first gate electrode, and the electric field of the conductor 503, which functions as the second gate electrode. In this specification, a transistor structure in which the channel formation region is electrically surrounded by the electric fields of the first and second gates is referred to as a surrounded channel (S-channel) structure.

[0192] In this specification and the like, a transistor with an S-channel structure refers to a transistor structure in which a channel formation region is electrically surrounded by the electric fields of one and the other of a pair of gate electrodes. The S-channel structure disclosed in this specification and the like differs from a fin structure and a planar structure. By adopting the S-channel structure, the transistor can be made more resistant to the short-channel effect, in other words, less susceptible to the short-channel effect.

[0193] 13B, the conductor 503 is extended to function as a wiring. However, the present invention is not limited to this, and a conductor functioning as a wiring may be provided below the conductor 503. Furthermore, it is not necessary to provide one conductor 503 for each transistor. For example, the conductor 503 may be shared by multiple transistors.

[0194] Note that although the conductor 503 in the transistor 500 has a stacked structure of the conductor 503a and the conductor 503b, the present invention is not limited to this. For example, the conductor 503 may have a single layer structure or a stacked structure of three or more layers.

[0195] Insulator 522 and insulator 524 function as gate insulators.

[0196] The insulator 522 preferably has a function of suppressing the diffusion of hydrogen (e.g., at least one of hydrogen atoms, hydrogen molecules, etc.). The insulator 522 preferably has a function of suppressing the diffusion of oxygen (e.g., at least one of oxygen atoms, oxygen molecules, etc.). For example, the insulator 522 preferably has a function of suppressing the diffusion of one or both of hydrogen and oxygen more than the insulator 524.

[0197] The insulator 522 may be an insulator containing an oxide of one or both of aluminum and hafnium, which are insulating materials. Aluminum oxide, hafnium oxide, or an oxide containing aluminum and hafnium (hafnium aluminate) is preferably used as the insulator. When the insulator 522 is formed using such a material, the insulator 522 functions as a layer that suppresses oxygen release from the oxide 530 to the substrate and diffusion of impurities such as hydrogen from the periphery of the transistor 500 to the oxide 530. Therefore, the insulator 522 can suppress diffusion of impurities such as hydrogen into the transistor 500 and suppress generation of oxygen vacancies in the oxide 530. Furthermore, reaction of the conductor 503 with oxygen contained in the insulator 524 or the oxide 530 can be suppressed.

[0198] Alternatively, the insulator may contain, for example, aluminum oxide, bismuth oxide, germanium oxide, niobium oxide, silicon oxide, titanium oxide, tungsten oxide, yttrium oxide, or zirconium oxide. Alternatively, these insulators may be nitrided. Furthermore, the insulator 522 may be formed by stacking silicon oxide, silicon oxynitride, or silicon nitride on these insulators.

[0199] The insulator 522 may be a single layer or a multilayer of an insulator containing a so-called high-k material, such as aluminum oxide, hafnium oxide, tantalum oxide, or zirconium oxide. As transistors become smaller and more highly integrated, thinning of the gate insulator can lead to problems such as leakage current. Using a high-k material as the gate insulator can reduce the gate potential during transistor operation while maintaining the physical film thickness. Alternatively, the insulator 522 may be made of a material with a high dielectric constant, such as lead zirconate titanate (PZT), strontium titanate (SrTiO3), or (Ba,Sr)TiO3 (BST).

[0200] The insulator 524 in contact with the oxide 530 can be made of, for example, silicon oxide, silicon oxynitride, or the like as appropriate.

[0201] During the manufacturing process of the transistor 500, heat treatment is preferably performed with the surface of the oxide 530 exposed. The heat treatment may be performed, for example, at a temperature of 100° C. to 600° C., more preferably 350° C. to 550° C. Note that the heat treatment is performed in a nitrogen gas or inert gas atmosphere, or an atmosphere containing an oxidizing gas at 10 ppm or more, 1% or more, or 10% or more. For example, the heat treatment is preferably performed in an oxygen atmosphere. This supplies oxygen to the oxide 530, thereby eliminating oxygen vacancies (V O) can be reduced. The heat treatment may be performed under reduced pressure. Alternatively, the heat treatment may be performed in an atmosphere containing 10 ppm or more, 1% or more, or 10% or more of an oxidizing gas after the heat treatment in a nitrogen gas or inert gas atmosphere to compensate for the desorbed oxygen. Alternatively, the heat treatment may be performed in an atmosphere containing 10 ppm or more, 1% or more, or 10% or more of an oxidizing gas, and then the heat treatment may be performed in a nitrogen gas or inert gas atmosphere.

[0202] By subjecting the oxide 530 to oxygen addition treatment, oxygen vacancies in the oxide 530 are repaired by the supplied oxygen. In other words, O Furthermore, the reaction of the hydrogen remaining in the oxide 530 with the supplied oxygen can be removed as HO (dehydration). As a result, the hydrogen remaining in the oxide 530 recombines with the oxygen vacancies to form V O The formation of H can be suppressed.

[0203] The insulators 522 and 524 may each have a stacked structure of two or more layers. In this case, the stacked structure is not limited to a stacked structure made of the same material, and may be a stacked structure made of different materials. The insulator 524 may be formed in an island shape overlapping the oxide 530a. In this case, the insulator 544 is configured to contact the side surface of the insulator 524 and the top surface of the insulator 522.

[0204] The conductor 542a and the conductor 542b are provided in contact with the top surface of the oxide 530b. The conductor 542a and the conductor 542b function as a source electrode and a drain electrode of the transistor 500, respectively.

[0205] As the conductor 542 (conductor 542a and conductor 542b), for example, a nitride containing tantalum, a nitride containing titanium, a nitride containing molybdenum, a nitride containing tungsten, a nitride containing tantalum and aluminum, or a nitride containing titanium and aluminum is preferably used. In one embodiment of the present invention, a nitride containing tantalum is particularly preferable. Also, for example, ruthenium oxide, ruthenium nitride, an oxide containing strontium and ruthenium, or an oxide containing lanthanum and nickel may be used. These materials are preferable because they are conductive materials that are resistant to oxidation or that maintain conductivity even when absorbing oxygen.

[0206] Note that hydrogen contained in the oxide 530b and the like may diffuse into the conductor 542a or the conductor 542b. In particular, by using a nitride containing tantalum for the conductors 542a and 542b, hydrogen contained in the oxide 530b and the like is likely to diffuse into the conductor 542a or the conductor 542b, and the diffused hydrogen may bond with nitrogen contained in the conductor 542a or the conductor 542b. In other words, hydrogen contained in the oxide 530b and the like may be absorbed by the conductor 542a or the conductor 542b.

[0207] Furthermore, it is preferable that no curved surface be formed between the side surface of the conductor 542 and the top surface of the conductor 542. The conductor 542 without such a curved surface can increase the cross-sectional area of ​​the conductor 542 in the cross section in the channel width direction. This can increase the conductivity of the conductor 542 and the on-state current of the transistor 500.

[0208] The insulator 571a is provided in contact with the top surface of the conductor 542a, and the insulator 571b is provided in contact with the top surface of the conductor 542b. The insulator 571 preferably functions as a barrier insulating film against oxygen. Therefore, the insulator 571 preferably has a function of suppressing oxygen diffusion. For example, the insulator 571 preferably has a function of suppressing oxygen diffusion more than the insulator 580. The insulator 571 may be, for example, a nitride containing silicon, such as silicon nitride. The insulator 571 preferably has a function of capturing impurities such as hydrogen. In this case, the insulator 571 may be an insulator of a metal oxide having an amorphous structure, such as aluminum oxide or magnesium oxide. In particular, using aluminum oxide having an amorphous structure or aluminum oxide having an amorphous structure as the insulator 571 is preferable because hydrogen can be more effectively captured or fixed. This enables the manufacture of a highly reliable transistor 500 and a semiconductor device with favorable characteristics.

[0209] The insulator 544 is provided to cover the insulator 524, the oxide 530a, the oxide 530b, the conductor 542, and the insulator 571. The insulator 544 preferably has a function of capturing and fixing hydrogen. In this case, the insulator 544 preferably includes an insulator such as silicon nitride or a metal oxide having an amorphous structure, such as aluminum oxide or magnesium oxide. Alternatively, for example, the insulator 544 may be a stacked film of aluminum oxide and silicon nitride on the aluminum oxide.

[0210] By providing the insulator 571 and the insulator 544 as described above, the conductor 542 can be surrounded by an insulator having a barrier property against oxygen. That is, oxygen contained in the insulator 524 and the insulator 580 can be prevented from diffusing into the conductor 542. This can prevent the conductor 542 from being directly oxidized by the oxygen contained in the insulator 524 and the insulator 580, which increases the resistivity and reduces the on-state current.

[0211] The insulator 552 functions as part of the gate insulator. The insulator 552 is preferably a barrier insulating film against oxygen. Any of the insulators that can be used for the insulator 574 described above can be used as the insulator 552. The insulator 552 can be an insulator containing one or both of an oxide of aluminum and hafnium. Examples of the insulator that can be used include aluminum oxide, hafnium oxide, an oxide containing aluminum and hafnium (hafnium aluminate), and an oxide containing hafnium and silicon (hafnium silicate). In this embodiment, aluminum oxide is used as the insulator 552. In this case, the insulator 552 contains at least oxygen and aluminum.

[0212] As shown in FIG. 13B, the insulator 552 is provided in contact with the top surface and side surfaces of the oxide 530b, the side surfaces of the oxide 530a, the side surfaces of the insulator 524, and the top surface of the insulator 522. That is, the regions of the oxide 530a, the oxide 530b, and the insulator 524 that overlap with the conductor 560 are covered with the insulator 552 in the cross section in the channel width direction. This allows the insulator 552, which has oxygen barrier properties, to block oxygen from being released from the oxides 530a and 530b during heat treatment or the like. This reduces the formation of oxygen vacancies (Vo) in the oxides 530a and 530b. This reduces the oxygen vacancies (Vo) and V formed in the region 530bc. O H can be reduced. Therefore, the electrical characteristics of the transistor 500 can be improved, and the reliability can be improved.

[0213] Conversely, even if the insulator 580, the insulator 550, or the like contains excessive amounts of oxygen, the oxygen can be prevented from being excessively supplied to the oxide 530a and the oxide 530b. Therefore, the region 530bc can prevent the regions 530ba and 530bb from being excessively oxidized, which would cause a decrease in the on-state current or the field-effect mobility of the transistor 500.

[0214] 13A , the insulator 552 is provided in contact with the side surfaces of the conductor 542, the insulator 544, the insulator 571, and the insulator 580. This reduces the oxidation of the side surface of the conductor 542 and the formation of an oxide film on the side surface. This reduces the on-state current or field-effect mobility of the transistor 500.

[0215] The insulator 552, together with the insulator 554, the insulator 550, and the conductor 560, needs to be provided in an opening formed in the insulator 580 or the like. To miniaturize the transistor 500, the insulator 552 preferably has a small thickness. The thickness of the insulator 552 is preferably 0.1 nm or more, 0.5 nm or more, or 1.0 nm or more, and preferably 1.0 nm or less, 3.0 nm or less, or 5.0 nm or less. Note that the above-described lower and upper limits can be combined. In this case, the insulator 552 only needs to have at least a region with the above-described thickness. The thickness of the insulator 552 is preferably thinner than the thickness of the insulator 550. In this case, the insulator 552 only needs to have at least a region with a thickness thinner than the insulator 550.

[0216] To form the insulator 552 into a thin film as described above, it is preferable to form the film by the ALD method. The ALD method includes a thermal ALD method in which a precursor and a reactant are reacted using only thermal energy, and a plasma-enhanced ALD method in which a plasma-excited reactant is used. The PEALD method may be preferable because it uses plasma, allowing film formation at a lower temperature.

[0217] The ALD method utilizes the self-regulating property of atoms and can deposit atoms one layer at a time, which has the advantages of enabling ultrathin film formation, film formation on structures with high aspect ratios, film formation with few defects such as pinholes, film formation with excellent coverage, film formation at low temperatures, etc. Therefore, the insulator 552 can be formed with good coverage on the side surfaces of an opening formed in the insulator 580 or the like and with the thin film thickness described above.

[0218] Some precursors used in ALD contain carbon and other impurities. Therefore, films formed by ALD may contain more carbon and other impurities than films formed by other film formation methods. Quantitative determination of impurities can be performed using secondary ion mass spectrometry (SIMS) or X-ray photoelectron spectroscopy (XPS).

[0219] The insulator 550 functions as part of the gate insulator. The insulator 550 is preferably disposed in contact with the upper surface of the insulator 552. The insulator 550 can be made of silicon oxide, silicon oxynitride, silicon nitride oxide, silicon nitride, silicon oxide doped with fluorine, silicon oxide doped with carbon, silicon oxide doped with carbon and nitrogen, silicon oxide having vacancies, or the like. Silicon oxide and silicon oxynitride are particularly preferred because they are stable against heat. In this case, the insulator 550 is an insulator containing at least oxygen and silicon.

[0220] Like the insulator 524, the insulator 550 preferably has a reduced concentration of impurities such as water and hydrogen. The thickness of the insulator 550 is preferably 1 nm or more, or 0.5 nm or more, and preferably 15 nm or less, or 20 nm or less. Note that the above-mentioned lower and upper limits can be combined. In this case, the insulator 550 only needs to have a region with the above-mentioned thickness in at least a portion thereof.

[0221] 13A and 13B show a configuration in which the insulator 550 is a single layer, but the present invention is not limited to this and the insulator 550 may have a laminated structure of two or more layers. For example, as shown in FIG. 15B, the insulator 550 may have a two-layer laminated structure of an insulator 550a and an insulator 550b on the insulator 550a.

[0222] As shown in FIG. 15B , when the insulator 550 has a two-layer stacked structure, the lower insulator 550a is preferably formed using an insulator that easily transmits oxygen, and the upper insulator 550b is preferably formed using an insulator that suppresses oxygen diffusion. This structure can suppress the diffusion of oxygen contained in the insulator 550a into the conductor 560. That is, it can suppress a decrease in the amount of oxygen supplied to the oxide 530. It can also suppress oxidation of the conductor 560 due to the oxygen contained in the insulator 550a. For example, the insulator 550a may be formed using a material that can be used for the insulator 550 described above, and the insulator 550b may be formed using an insulator containing one or both of aluminum and hafnium oxides. Examples of the insulator that can be used include aluminum oxide, hafnium oxide, an oxide containing aluminum and hafnium (hafnium aluminate), and an oxide containing hafnium and silicon (hafnium silicate). In this embodiment, hafnium oxide is used as the insulator 550b. In this case, the insulator 550b contains at least oxygen and hafnium. The thickness of the insulator 550b is preferably 0.5 nm or more, or 1.0 nm or more, and preferably 3.0 nm or less, or 5.0 nm or less. The above-mentioned lower and upper limits can be combined. In this case, the insulator 550b only needs to have a region with the above-mentioned thickness in at least a portion.

[0223] When silicon oxide, silicon oxynitride, or the like is used for the insulator 550a, the insulator 550b may be an insulating material, such as a high-k material with a high dielectric constant. By forming the gate insulator as a layered structure of the insulators 550a and 550b, a layered structure that is thermally stable and has a high dielectric constant can be achieved. This allows the gate potential applied during transistor operation to be reduced while maintaining the physical thickness of the gate insulator. Furthermore, the equivalent oxide thickness (EOT) of the insulator functioning as the gate insulator can be reduced. This allows the dielectric strength of the insulator 550 to be increased.

[0224] The insulator 554 functions as part of the gate insulator. A barrier insulating film against hydrogen is preferably used as the insulator 554. This can prevent impurities such as hydrogen contained in the conductor 560 from diffusing into the insulator 550 and the oxide 530b. The insulator 554 can be any of the insulators that can be used for the insulator 576. For example, silicon nitride formed by a PEALD method can be used as the insulator 554. In this case, the insulator 554 contains at least nitrogen and silicon.

[0225] The insulator 554 may further have a barrier property against oxygen, which can prevent oxygen contained in the insulator 550 from diffusing into the conductor 560.

[0226] The insulator 554, together with the insulator 552, the insulator 550, and the conductor 560, needs to be provided in an opening formed in the insulator 580 or the like. To miniaturize the transistor 500, the insulator 554 preferably has a small thickness. The thickness of the insulator 554 is preferably 0.1 nm or more, 0.5 nm or more, or 1.0 nm or more, and preferably 3.0 nm or less, or 5.0 nm or less. Note that the above-described lower and upper limits can be combined. In this case, the insulator 554 only needs to have at least a region with the above-described thickness. The thickness of the insulator 554 is preferably thinner than the thickness of the insulator 550. In this case, the insulator 554 only needs to have at least a region with a thickness thinner than the insulator 550.

[0227] The conductor 560 functions as a first gate electrode of the transistor 500. The conductor 560 preferably includes a conductor 560a and a conductor 560b disposed over the conductor 560a. For example, the conductor 560a is preferably disposed so as to surround the bottom and side surfaces of the conductor 560b. As shown in FIGS. 13A and 13B, the height of the top of the conductor 560 roughly coincides with the height of the top of the insulator 550. Note that although the conductor 560 is shown as having a two-layer structure of the conductor 560a and the conductor 560b in FIGS. 13A and 13B, the conductor 560 may have a single-layer structure or a stacked structure of three or more layers, other than the two-layer structure.

[0228] The conductor 560a is preferably made of a conductive material that has a function of suppressing the diffusion of impurities such as hydrogen atoms, hydrogen molecules, water molecules, nitrogen atoms, nitrogen molecules, nitrogen oxide molecules, copper atoms, etc. Alternatively, it is preferably made of a conductive material that has a function of suppressing the diffusion of oxygen (for example, at least one of oxygen atoms, oxygen molecules, etc.).

[0229] Furthermore, since conductor 560a has the function of suppressing oxygen diffusion, it is possible to suppress a decrease in conductivity due to oxidation of conductor 560b caused by oxygen contained in insulator 550. As a conductive material having the function of suppressing oxygen diffusion, it is preferable to use, for example, titanium, titanium nitride, tantalum, tantalum nitride, ruthenium, ruthenium oxide, or the like.

[0230] Furthermore, since the conductor 560 also functions as wiring, it is preferable to use a conductor with high conductivity. For example, the conductor 560b can be a conductive material containing tungsten, copper, or aluminum as a main component. The conductor 560b can have a layered structure. Specifically, for example, the conductor 560b can have a layered structure of titanium or titanium nitride and the above conductive material.

[0231] Furthermore, in the transistor 500, the conductor 560 is formed in a self-aligned manner so as to fill an opening formed in the insulator 580 or the like. By forming the conductor 560 in this manner, the conductor 560 can be reliably placed in the region between the conductor 542a and the conductor 542b without alignment.

[0232] 13B, in the channel width direction of the transistor 500, the height of the bottom surface of the conductor 560 in a region where the conductor 560 does not overlap with the oxide 530b is preferably lower than the height of the bottom surface of the oxide 530b when the bottom surface of the insulator 522 is used as the reference. When the conductor 560, which functions as a gate electrode, covers the side and top surfaces of the channel formation region of the oxide 530b via the insulator 550 or the like, the electric field of the conductor 560 can be easily applied to the entire channel formation region of the oxide 530b. Therefore, the on-state current of the transistor 500 can be increased, and the frequency characteristics can be improved. The difference between the height of the bottom surface of conductor 560 and the height of the bottom surface of oxide 530b in the region where oxide 530a and oxide 530b do not overlap with conductor 560, relative to the bottom surface of insulator 522, is preferably 0 nm or more, 3 nm or more, or 5 nm or more, and is preferably 20 nm or less, 50 nm or less, or 100 nm or less. Note that the above-mentioned lower limit and upper limit values ​​can be combined with each other.

[0233] The insulator 580 is provided on the insulator 544, and openings are formed in the regions where the insulator 550 and the conductor 560 are to be provided. The top surface of the insulator 580 may be planarized.

[0234] The insulator 580, which functions as an interlayer film, preferably has a low dielectric constant. Using a material with a low dielectric constant as the interlayer film can reduce parasitic capacitance between wirings. The insulator 580 is preferably formed using, for example, the same material as the insulator 516. In particular, silicon oxide and silicon oxynitride are preferred because they are thermally stable. In particular, materials such as silicon oxide, silicon oxynitride, and silicon oxide with vacancies are preferred because they can easily form a region containing oxygen that is released by heating.

[0235] The insulator 580 preferably has a low concentration of impurities such as water and hydrogen. For example, the insulator 580 may be formed using an oxide containing silicon, such as silicon oxide or silicon oxynitride, as appropriate.

[0236] The insulator 574 preferably functions as a barrier insulating film that suppresses diffusion of impurities such as water and hydrogen from above into the insulator 580 and preferably has a function of capturing impurities such as hydrogen. The insulator 574 also preferably functions as a barrier insulating film that suppresses oxygen permeation. The insulator 574 may be an insulator made of a metal oxide having an amorphous structure, such as aluminum oxide. In this case, the insulator 574 contains at least oxygen and aluminum. By providing the insulator 574, which is in contact with the insulator 580 and has a function of capturing impurities such as hydrogen, in the region between the insulators 512 and 581, the insulator 574 can capture impurities such as hydrogen contained in the insulator 580 and maintain a constant amount of hydrogen in the region. In particular, using aluminum oxide having an amorphous structure as the insulator 574 is preferable because it may be able to more effectively capture or fix hydrogen. This enables the manufacture of a highly reliable transistor 500 and semiconductor device with excellent characteristics.

[0237] The insulator 576 functions as a barrier insulating film that suppresses diffusion of impurities such as water and hydrogen from above into the insulator 580. The insulator 576 is disposed over the insulator 574. The insulator 576 is preferably a nitride containing silicon, such as silicon nitride or silicon nitride oxide. For example, the insulator 576 may be formed using silicon nitride deposited by a sputtering method. A high-density silicon nitride film can be formed by depositing the insulator 576 by a sputtering method. Alternatively, the insulator 576 may be formed by stacking a silicon nitride film deposited by a PEALD method or a CVD method on the silicon nitride film deposited by a sputtering method.

[0238] One of the first and second terminals of the transistor 500 is electrically connected to a conductor 540a functioning as a plug, and the other of the first and second terminals of the transistor 500 is electrically connected to a conductor 540b. Note that in this specification and the like, the conductors 540a and 540b are collectively referred to as conductors 540.

[0239] For example, the conductor 540a is provided in a region overlapping with the conductor 542a. Specifically, in the region overlapping with the conductor 542a, openings are formed in the insulators 571, 544, 580, 574, 576, and 581 shown in FIG. 13A and insulators 582 and 586 shown in FIG. 12, and the conductor 540a is provided inside the openings. For example, the conductor 540b is provided in a region overlapping with the conductor 542b. Specifically, in the region overlapping with the conductor 542b, openings are formed in the insulators 571, 544, 580, 574, 576, and 581 shown in Fig. 13A and insulators 582 and 586 shown in Fig. 12, and the conductor 540b is provided inside the openings. The insulators 582 and 586 will be described later.

[0240] 13A, an insulator 541a may be provided as an insulator having a barrier property against impurities between the conductor 540a and a side surface of the opening in a region overlapping with the conductor 542a. Similarly, an insulator 541b may be provided as an insulator having a barrier property against impurities between the conductor 540b and a side surface of the opening in a region overlapping with the conductor 542b. Note that in this specification and the like, the insulators 541a and 541b are collectively referred to as the insulator 541.

[0241] The conductors 540a and 540b are preferably made of a conductive material containing tungsten, copper, or aluminum as a main component. The conductors 540a and 540b may have a layered structure.

[0242] Furthermore, when the conductor 540 has a layered structure, it is preferable to use a conductive material that has the function of suppressing the permeation of impurities such as water and hydrogen for the insulators 574, 576, 581, 580, 544, and the first conductor disposed near the insulator 571. For example, it is preferable to use tantalum, tantalum nitride, titanium, titanium nitride, ruthenium, ruthenium oxide, or the like. Furthermore, the conductive material that has the function of suppressing the permeation of impurities such as water and hydrogen may be used in a single layer or a layered structure. Furthermore, it is possible to suppress impurities such as water and hydrogen contained in layers above the insulator 576 from being mixed into the oxide 530 through the conductors 540a and 540b.

[0243] The insulators 541a and 541b may be a barrier insulating film that can be used for the insulator 544, etc. For example, the insulators 541a and 541b may be made of an insulator such as silicon nitride, aluminum oxide, or silicon nitride oxide. The insulators 541a and 541b are provided in contact with the insulators 574, 576, and 571, and thus can prevent impurities such as water and hydrogen contained in the insulator 580 from entering the oxide 530 through the conductors 540a and 540b. Silicon nitride is particularly suitable because it has a high blocking property against hydrogen. Furthermore, oxygen contained in the insulator 580 can be prevented from being absorbed by the conductors 540a and 540b.

[0244] When insulators 541a and 541b are formed into a layered structure as shown in FIG. 13A, it is preferable that the first insulator in contact with the inner wall of an opening such as insulator 580 and the second insulator inside it be made of a combination of a barrier insulating film against oxygen and a barrier insulating film against hydrogen.

[0245] For example, aluminum oxide formed by the ALD method can be used as the first insulator, and silicon nitride formed by the PEALD method can be used as the second insulator. With this structure, oxidation of the conductor 540 can be suppressed and hydrogen contamination of the conductor 540 can be reduced.

[0246] Although the transistor 500 has a structure in which the first insulator of the insulator 541 and the second conductor of the insulator 541 are stacked, the present invention is not limited to this. For example, the insulator 541 may be provided as a single layer or a stacked structure of three or more layers. Furthermore, the transistor 500 has a structure in which the first conductor of the conductor 540 and the second conductor of the conductor 540 are stacked, but the present invention is not limited to this. For example, the conductor 540 may be provided as a single layer or a stacked structure of three or more layers.

[0247] 12, conductors 610 and 612, which function as wiring and are in contact with the upper portions of conductors 540a and 540b, may be disposed. Conductor 610 and conductor 612 are preferably made of a conductive material containing tungsten, copper, or aluminum as a main component. The conductors may also have a layered structure. Specifically, for example, the conductors may be a layered structure of titanium or titanium nitride and the above conductive material. The conductors may be formed so as to be embedded in openings provided in an insulator.

[0248] The structure of the transistors included in the group of semiconductor devices of the present invention is not limited to the transistor 500 shown in Figures 12, 13A, 13B, and 14. The structure of the transistors included in the group of semiconductor devices of the present invention may be changed depending on the situation.

[0249] For example, the transistor 500 illustrated in FIGS. 12, 13A, 13B, and 14 may have the structure illustrated in FIG. 16. The transistor in FIG. 16 differs from the transistor 500 illustrated in FIGS. 12, 13A, 13B, and 14 in that it includes an oxide 543a and an oxide 543b. Note that in this specification and the like, the oxide 543a and the oxide 543b are collectively referred to as the oxide 543. The cross-sectional structure of the transistor in FIG. 16 in the channel width direction can be similar to that of the cross-section of the transistor 500 illustrated in FIG. 13B.

[0250] The oxide 543a is provided between the oxide 530b and the conductor 542a, and the oxide 543b is provided between the oxide 530b and the conductor 542b. Here, the oxide 543a is preferably in contact with the upper surface of the oxide 530b and the lower surface of the conductor 542a. The oxide 543b is preferably in contact with the upper surface of the oxide 530b and the lower surface of the conductor 542b.

[0251] The oxide 543 preferably has a function of suppressing oxygen permeation. Placing the oxide 543, which has a function of suppressing oxygen permeation, between the conductor 542 functioning as a source electrode or a drain electrode and the oxide 530b is preferable because the electrical resistance between the conductor 542 and the oxide 530b can be reduced. Such a structure can improve the electrical characteristics, field-effect mobility, and reliability of the transistor 500 in some cases.

[0252] Alternatively, a metal oxide containing element M may be used as oxide 543. In particular, element M may be aluminum, gallium, yttrium, or tin. Preferably, oxide 543 has a higher concentration of element M than oxide 530b. Alternatively, oxide 543 may be gallium oxide. Alternatively, oxide 543 may be a metal oxide such as In-M-Zn oxide. Specifically, the atomic ratio of element M to In in the metal oxide used for oxide 530b is preferably greater than the atomic ratio of element M to In in the metal oxide used for oxide 530b. Furthermore, the film thickness of oxide 543 is preferably 0.5 nm or more or 1 nm or more, and is preferably 2 nm or less, 3 nm or less, or 5 nm or less. The above-mentioned lower and upper limits may be combined. Preferably, oxide 543 is crystalline. When oxide 543 is crystalline, oxygen release from oxide 530 can be effectively suppressed. For example, if the oxide 543 has a crystal structure such as a hexagonal crystal structure, the release of oxygen from the oxide 530 may be suppressed.

[0253] An insulator 582 is provided on the insulator 581, and an insulator 586 is provided on the insulator 582.

[0254] The insulator 582 is preferably made of a substance that has a barrier property against oxygen and hydrogen. Therefore, the insulator 582 can be made of a material similar to that of the insulator 514. For example, the insulator 582 is preferably made of a metal oxide such as aluminum oxide, hafnium oxide, or tantalum oxide.

[0255] The insulator 586 can be made of a material similar to that of the insulator 320. The use of a material with a relatively low dielectric constant for these insulators can reduce parasitic capacitance between wirings. For example, the insulator 586 can be made of a silicon oxide film, a silicon oxynitride film, or the like.

[0256] Next, a description will be given of the capacitor 600 and its peripheral wiring or plugs included in the semiconductor device shown in Figures 12 and 14. Note that the capacitor 600, wiring, and / or plugs are provided above the transistor 500 shown in Figures 12 and 14.

[0257] The capacitor 600 includes, for example, a conductor 610 , a conductor 620 , and an insulator 630 .

[0258] A conductor 610 is provided over one of the conductors 540a and 540b, the conductor 546, and the insulator 586. The conductor 610 functions as one of a pair of electrodes of a capacitor 600.

[0259] A conductor 612 is provided over the other of the conductor 540a and the conductor 540b and over the insulator 586. The conductor 612 functions as a plug, a wiring, a terminal, or the like that electrically connects the transistor 500 to a circuit element, a wiring, or the like arranged above it.

[0260] The conductor 612 and the conductor 610 may be formed at the same time.

[0261] A metal film containing an element selected from molybdenum, titanium, tantalum, tungsten, aluminum, copper, chromium, neodymium, and scandium, or a metal nitride film containing any of the above elements (tantalum nitride film, titanium nitride film, molybdenum nitride film, tungsten nitride film), or the like can be used for the conductor 612 and the conductor 610. Alternatively, a conductive material such as indium tin oxide, indium oxide containing tungsten oxide, indium zinc oxide containing tungsten oxide, indium oxide containing titanium oxide, indium tin oxide containing titanium oxide, indium zinc oxide, or indium tin oxide to which silicon oxide is added can also be used.

[0262] 12, the conductor 612 and the conductor 610 have a single-layer structure, but are not limited to this structure and may have a stacked structure of two or more layers. For example, a conductor having a barrier property and a conductor having high adhesion to the conductor having high conductivity may be formed between a conductor having a barrier property and a conductor having high conductivity.

[0263] An insulator 630 is provided on the insulator 586 and the conductor 610. The insulator 630 functions as a dielectric sandwiched between the pair of electrodes of the capacitor 600.

[0264] The insulator 630 can be, for example, silicon oxide, silicon oxynitride, silicon nitride oxide, silicon nitride, aluminum oxide, aluminum oxynitride, aluminum nitride oxide, aluminum nitride, hafnium oxide, hafnium oxynitride, hafnium nitride oxide, hafnium nitride, zirconium oxide, or the like. The insulator 630 can be formed as a stacked layer or a single layer using any of the above-mentioned materials.

[0265] Furthermore, for example, a laminated structure of a material with high dielectric strength, such as silicon oxynitride, and a high dielectric constant (high-k) material may be used for the insulator 630. With this configuration, the capacitor 600 can ensure sufficient capacitance by having an insulator with high dielectric constant (high-k), and the insulator with high dielectric strength improves the dielectric strength, thereby suppressing electrostatic breakdown of the capacitor 600.

[0266] Examples of high-dielectric-constant (high-k) materials (materials with a high relative dielectric constant) insulators include gallium oxide, hafnium oxide, zirconium oxide, oxides containing aluminum and hafnium, oxynitrides containing aluminum and hafnium, oxides containing silicon and hafnium, oxynitrides containing silicon and hafnium, and nitrides containing silicon and hafnium.

[0267] Alternatively, the insulator 630 may be a single layer or a multilayer insulator containing a high-k material, such as aluminum oxide, hafnium oxide, tantalum oxide, zirconium oxide, lead zirconate titanate (PZT), strontium titanate (SrTiO3), or (Ba,Sr)TiO3 (BST). The insulator 630 may also be a compound containing hafnium and zirconium. As semiconductor devices become smaller and more highly integrated, thinning of the gate insulator and the dielectric used in the capacitor can cause problems such as leakage current in transistors and capacitors. Using a high-k material for the insulator functioning as the gate insulator and the dielectric used in the capacitor allows for a reduction in the gate potential during transistor operation and a secure capacitance value while maintaining the physical film thickness.

[0268] The conductor 620 is provided to overlap with the conductor 610 with the insulator 630 placed therebetween. The conductor 610 functions as one of a pair of electrodes of the capacitor 600.

[0269] The conductor 620 can be made of a conductive material such as a metal material, an alloy material, or a metal oxide material. It is preferable to use a high-melting-point material such as tungsten or molybdenum, which has both heat resistance and conductivity, and tungsten is particularly preferable. When the conductor 620 is formed simultaneously with other structures such as a conductor, a low-resistance metal material such as Cu (copper) or Al (aluminum) can be used. For example, the conductor 620 can be made of a material that can be used for the conductor 610. The conductor 620 may have a laminated structure of two or more layers instead of a single layer structure.

[0270] An insulator 640 is provided over the conductor 620 and the insulator 630. For the insulator 640, for example, a film having a barrier property that prevents diffusion of hydrogen, impurities, and the like into a region where the transistor 500 is provided is preferably used. Therefore, a material similar to that of the insulator 324 can be used.

[0271] An insulator 650 is provided over the insulator 640. The insulator 650 can be provided using a material similar to that of the insulator 320. The insulator 650 may also function as a planarizing film that covers the uneven shape below it. Therefore, the insulator 650 can be made of, for example, a material that can be used for the insulator 324.

[0272] 12 and 14 is a planar type, the shape of the capacitor is not limited to this. The capacitor 600 may be, for example, a cylindrical type instead of a planar type.

[0273] 12, an insulator 411, an insulator 412, an insulator 413, and an insulator 414 are provided in this order above an insulator 650. A conductor 416 functioning as a plug or a wiring is provided in the insulators 411, 412, and 413. For example, the conductor 416 can be provided in a region overlapping with a conductor 660 described later.

[0274] Furthermore, openings are provided in the insulators 630, 640, and 650 in regions overlapping with the conductor 612, and the conductor 660 is provided to fill the openings. The conductor 660 functions as a plug or wiring electrically connected to the conductor 416 included in the above-described wiring layer.

[0275] The insulators 411 and 414 are preferably made of an insulator that has barrier properties against impurities such as water and hydrogen, similar to the insulator 324. Therefore, the insulators 411 and 414 can be made of a material that can be used for the insulator 324, for example.

[0276] For the insulators 412 and 413, similar to the insulator 326, it is preferable to use an insulator with a relatively low dielectric constant in order to reduce parasitic capacitance between wirings.

[0277] Furthermore, the conductor 612 and the conductor 416 can be formed using, for example, the same material as the conductor 328 and the conductor 330 .

[0278] <Example of a configuration of a transistor and a ferroelectric capacitor> Next, a configuration will be described in which a dielectric that may have ferroelectricity is provided in and around a transistor 500 that includes a metal oxide in a channel formation region.

[0279] FIG. 17A shows an example of a transistor configuration in which a dielectric that may have ferroelectric properties is provided in the configuration of transistor 500 such as that of FIG. 12 or FIG. 13A.

[0280] 17A has a configuration in which the insulator 522 functioning as the second gate insulator is replaced with an insulator 520. As one example, the insulator 520 can be a dielectric material that can have ferroelectricity.

[0281] 17A can have a ferroelectric capacitor between the conductor 503, which functions as the second gate electrode, and the oxide 530. In other words, the transistor of FIG. 17A can be an FeFET (Ferroelectric FET) in which a dielectric that may have ferroelectricity is provided in a part of the second gate insulator.

[0282] Materials that can have ferroelectric properties include hafnium oxide, zirconium oxide, and HfZrO X (X is a real number greater than 0), hafnium oxide to which element J1 (here, element J1 is zirconium (Zr), silicon (Si), aluminum (Al), gadolinium (Gd), yttrium (Y), lanthanum (La), strontium (Sr), etc.) is added, and zirconium oxide to which element J2 (here, element J2 is hafnium (Hf), silicon (Si), aluminum (Al), gadolinium (Gd), yttrium (Y), lanthanum (La), strontium (Sr), etc.) is added. Furthermore, materials that may have ferroelectricity include PbTiO X Piezoelectric ceramics having a perovskite structure, such as barium strontium titanate (BST), strontium titanate, lead zirconate titanate (PZT), strontium bismuth tantalate (SBT), bismuth ferrite (BFO), and barium titanate, may also be used. Ferroelectric materials may be, for example, a plurality of materials selected from the above-listed materials, or a laminated structure made of a plurality of materials selected from the above-listed materials. Incidentally, hafnium oxide, zirconium oxide, HfZrO X and materials in which the element J1 is added to hafnium oxide, the crystal structure (characteristics) of which may change not only depending on the film formation conditions but also on various processes, etc., and therefore in this specification and the like, materials that exhibit ferroelectricity are not only called ferroelectrics, but are also called materials that can have ferroelectricity or materials that can be made to have ferroelectricity.

[0283] Although insulator 520 is illustrated as a single layer in FIG. 17A, insulator 520 may be an insulating film of two or more layers including a dielectric material that may have ferroelectricity. A specific example of such a transistor is shown in FIG. 17B. In FIG. 17B, insulator 520 includes insulator 520a and insulator 520b, for example. Insulator 520a is provided on the top surface of insulator 516 and conductor 503, and insulator 520b is provided on the top surface of insulator 520a.

[0284] For example, a dielectric material that may have ferroelectricity may be used as the insulator 520a. For example, silicon oxide may be used as the insulator 520b. Alternatively, for example, silicon oxide may be used as the insulator 520a and a dielectric material that may have ferroelectricity may be used as the insulator 520b.

[0285] As shown in Figure 17B, by using two layers of insulator 520, with one layer being a dielectric that may have ferroelectric properties and the other layer being silicon oxide, it is possible to suppress leakage current flowing between conductor 503, which functions as a gate electrode, and oxide 530.

[0286] 17C shows an example of the configuration of a transistor in which the insulator 520 has three layers. In Fig. 17C, the insulator 520 includes, for example, an insulator 520a, an insulator 520b, and an insulator 520c. The insulator 520c is provided on the top surface of the insulator 516 and the conductor 503, the insulator 520a is provided on the top surface of the insulator 520c, and the insulator 520b is provided on the top surface of the insulator 520a.

[0287] The insulator 520a may be, for example, a dielectric material that may have ferroelectricity, and the insulators 520b and 520c may be, for example, silicon oxide.

[0288] The respective configurations of the transistors and ferroelectric capacitors shown in FIGS. 17A to 17C can be applied to, for example, the transistors FM1 to FM3 described in the first embodiment.

[0289] FIG. 18 shows an example of a transistor configuration in which a dielectric that may have ferroelectric properties is provided in the configuration of transistor 500 of FIGS. 12, 13A, etc., which is different from the transistors of FIGS. 17A to 17C.

[0290] The transistor shown in Figure 18 shows an example of a transistor configuration in which a dielectric that may have ferroelectric properties is provided above insulators 552, 550, and 554 that function as first gate insulators, conductor 560 that functions as a first gate electrode, and a partial region of insulator 580.

[0291] Specifically, insulator 561 is provided so as to be in contact with insulator 552, insulator 550, insulator 554, conductor 560, and partial regions of insulator 580. As an example, insulator 561 can be made of a dielectric material that can have ferroelectricity and can be applied to insulator 520 in FIG. 17A.

[0292] A conductor 562 is provided to be in contact with an upper portion of the insulator 561. The conductor 562 can be provided using, for example, the same material as the conductors 328 and 330.

[0293] Therefore, with the configuration of the transistor in FIG. 18, a ferroelectric capacitor can be provided between the conductor 503 functioning as the first gate electrode and the conductor 562.

[0294] The insulator 561 may have a laminated structure of two or more layers, similar to the insulator 520 shown in FIGS. 17B and 17C.

[0295] Furthermore, the respective configurations of the transistor and ferroelectric capacitor shown in FIG. 18 can be applied to, for example, the transistor M1 and capacitor FC1 described in the first embodiment.

[0296] FIG. 19A shows an example of a transistor configuration in which a dielectric that may have ferroelectric properties is provided in the configuration of transistor 500, such as in FIGS. 12 and 13A, which is different from the transistors of FIGS. 17A to 17C and 18, respectively.

[0297] 19A, an insulator 602 is provided in an opening that overlaps with the conductor 542b and is provided in the insulators 544, 571b, 580, 574, 576, and 581. Specifically, in the opening, an insulator 541b is provided on a side surface of the opening, a conductor 540b is provided over the insulator 541b and over the conductor 542b that is the bottom of the opening, an insulator 602 is provided over a portion of the insulator 581 and over the conductor 540b, and a conductor 613 is provided over the insulator 602 to fill the remaining opening.

[0298] As another specific configuration example, within the opening, an insulator 541b is provided on the side of the opening, a conductor 540b is provided on the insulator 541b, an insulator 602 is provided in a portion of the insulator 581, on the conductor 540b, and on the conductor 542b at the bottom of the opening, and a conductor 613 is provided on the insulator 602 so as to fill the remaining opening.

[0299] For example, the insulator 602 may be a dielectric material that may have ferroelectric properties, which may be applicable to the insulator 520 in FIG. 17A.

[0300] Among these, hafnium oxide or a material containing hafnium oxide and zirconium oxide is preferable as a dielectric that can have ferroelectricity because it can be processed into a thin film of a few nanometers and still have ferroelectricity. Here, the film thickness of the insulator 602 can be 100 nm or less, preferably 50 nm or less, and more preferably 10 nm or less. By thinning the insulator 602, it can be combined with a miniaturized transistor to form a semiconductor device.

[0301] As the insulator 602, a material having hafnium oxide and zirconium oxide (HfZrO x When using the above-mentioned film, it is preferable to form the film by using a thermal ALD method.

[0302] Furthermore, when the insulator 602 is formed by the thermal ALD method, it is preferable to use a material that does not contain hydrocarbons (also referred to as Hydro Carbon, HC) as a precursor. If the insulator 602 contains either or both of hydrogen and carbon, crystallization of the insulator 602 may be hindered. For this reason, as described above, it is preferable to use a precursor that does not contain hydrocarbons to reduce the concentration of either or both of hydrogen and carbon in the insulator 602. For example, a chlorine-based material can be used as a precursor that does not contain hydrocarbons. Note that the insulator 602 may be formed using a material containing hafnium oxide and zirconium oxide (HfZrO x ) is used, HfCl4 and / or ZrCl4 may be used as the precursor.

[0303] Furthermore, when forming the insulator 602 using a thermal ALD method, the oxidizing agent can be H2O or O3. Note that using O3 as the oxidizing agent for the thermal ALD method is more preferable than using H2O because it can reduce the hydrogen concentration in the film. However, the oxidizing agent for the thermal ALD method is not limited to this. For example, the oxidizing agent for the thermal ALD method may include one or more selected from O2, O3, N2O, NO2, H2O, and H2O2.

[0304] The conductor 613 can be formed using, for example, a material similar to that of the conductors 328 and 330 .

[0305] The conductor 613 can be formed by ALD or CVD. For example, titanium nitride can be formed by thermal ALD. Here, the conductor 613 is preferably formed by a method in which the substrate is heated, as in the thermal ALD method. For example, the substrate temperature can be set to room temperature or higher, preferably 300°C or higher, more preferably 325°C or higher, and even more preferably 350°C or higher. Alternatively, the substrate temperature can be set to 500°C or lower, preferably 450°C or lower. For example, the substrate temperature can be set to about 400°C.

[0306] By forming the conductor 613 within the temperature range described above, it is possible to impart ferroelectricity to the insulator 602 without performing a high-temperature bake treatment (e.g., a bake treatment at a heat treatment temperature of 400°C or higher or 500°C or higher) after forming the conductor 613. Furthermore, by forming the conductor 613 using the ALD method, which causes relatively little damage to the base, as described above, it is possible to prevent the crystal structure of the insulator 602 from being excessively destroyed, thereby enhancing the ferroelectricity of the insulator 602.

[0307] For example, when the conductor 613 is formed by sputtering, there is a possibility that damage may occur in the underlayer, in this case the insulator 602. For example, when the insulator 602 is made of a material containing hafnium oxide and zirconium oxide (HfZrO x When the conductor 613 is formed by sputtering, the HfZrO x Damage occurs to HfZrO x The crystal structure (typically a cubic crystal structure) of HfZrO may be destroyed by heat treatment. x There are also methods to repair the damage to the crystal structure of HfZrO formed by sputtering. x Damage in, e.g., HfZrO x Dangling bonds in (e.g., O * ) and HfZrO x The hydrogen contained in the xIn some cases, damage in the crystal structure of the material cannot be repaired.

[0308] Therefore, HfZrO used as the insulator 602 x It is preferable to use a material that does not contain hydrogen or that contains extremely little hydrogen for the insulator 602. By using a material that does not contain hydrogen or that contains extremely little hydrogen for the insulator 602, the crystallinity of the insulator 602 can be improved, resulting in a structure with high ferroelectricity.

[0309] As described above, in one embodiment of the present invention, for example, a ferroelectric material is formed as the insulator 602 by thermal ALD using a hydrocarbon-free precursor (typically a chlorine-based precursor) and an oxidizer (typically O). Then, the conductor 613 is formed by thermal ALD (typically at 400° C. or higher). This allows the crystallinity or ferroelectricity of the insulator 602 to be improved without annealing after the formation of the conductor 613, in other words, by utilizing the temperature during the formation of the conductor 613. Note that improving the crystallinity or ferroelectricity of the insulator 602 by utilizing the temperature during the formation of the conductor 613 without annealing after the formation of the conductor 613 is sometimes referred to as self-annealing.

[0310] The configuration of the transistor in FIG. 19A allows a ferroelectric capacitor to be provided between the conductor 540b and the conductor 613 in the opening included in the region overlapping with the conductor 542b.

[0311] The insulator 602 may have a laminated structure of two or more layers, similar to the insulator 520 shown in FIGS. 17B and 17C.

[0312] FIG. 19B illustrates an example of a transistor configuration in which a dielectric that may have ferroelectric properties is provided in the configuration of transistor 500, such as that of FIGS. 12 and 13A, which is different from the transistors of FIGS. 17A-17C, 18, and 19A.

[0313] 19B has a structure in which the insulators 552, 550, and 554 functioning as the first gate insulator are replaced with an insulator 553. For example, the insulator 553 can be a dielectric that can have ferroelectricity and can be used for the insulator 520 in FIG. 17A.

[0314] Therefore, the transistor of Figure 19B can have a ferroelectric capacitor between the conductor 560, which functions as the first gate electrode, and the oxide 530. In other words, the transistor of Figure 19B can be an FeFET in which a dielectric that may have ferroelectric properties is provided in a portion of the first gate insulator.

[0315] Note that the insulator 553 may have a stacked structure of two or more layers, similar to the insulator 520 shown in FIGS. 17B and 17C.

[0316] In addition, in FIG. 19B, the insulator 552, the insulator 550, and the insulator 554 are replaced with the insulator 553. However, as another example of the configuration, at least one of the insulators 552, 550, and 554 may be replaced with the insulator 553, and the remaining insulator and the insulator 553 may form a laminated structure.

[0317] Furthermore, the respective configurations of the transistor and ferroelectric capacitor shown in FIGS. 19A and 19B can be applied to, for example, the transistor M1 and capacitor FC1 described in the first embodiment.

[0318] FIG. 20A shows an example of the configuration of a transistor 500 and a capacitor, in which a capacitor including a dielectric material that may have ferroelectricity is provided around the transistor 500.

[0319] 20A , for example, a plurality of openings are formed in the insulators 544, 571b, 580, 574, 576, and 581 in a region overlapping with the conductor 542b. A conductor 540c functioning as a plug is provided inside one of the openings, and an insulator 541c serving as an insulator with a barrier property against impurities is provided between a side surface of the opening and the conductor 540c. A conductor 540d functioning as a plug is provided inside another of the openings, and an insulator 541d serving as an insulator with a barrier property against impurities is provided between a side surface of the opening and the conductor 540d. The conductor 540c and the conductor 540d can be made of, for example, a material that can be used for the conductor 540a and the conductor 540b, and the insulator 541c and the insulator 541d can be made of, for example, a material that can be used for the insulator 541a and the insulator 541b.

[0320] An insulator 601 is provided on the upper part of the conductor 540c and the conductor 540d so as to be in contact with them. As an example, the insulator 601 can be made of a dielectric material that can have ferroelectricity and can be used for the insulator 520 in FIG. 17A.

[0321] A conductor 611 is provided to be in contact with an upper portion of the insulator 601. The conductor 611 can be provided using, for example, the same material as the conductors 328 and 330.

[0322] Therefore, with the configuration shown in FIG. 20A, a ferroelectric capacitor can be provided between the conductor 540c and the conductor 540d that function as plugs and the conductor 611.

[0323] The insulator 601 may have a laminated structure of two or more layers, similar to the insulator 520 shown in FIGS. 17B and 17C.

[0324] 20A shows two plugs (conductor 540c and conductor 540d) in contact with insulator 601, but the number of plugs may be one or three or more. In other words, while Fig. 20A shows an example in which two openings having conductors as plugs are provided in the region overlapping with insulator 601, the number of openings provided in the region overlapping with insulator 601 may be one or three or more.

[0325] FIG. 20B shows an example of a configuration of a transistor 500 and a capacitor, which is different from that of FIG. 20A, in which a capacitor including a dielectric material that may have ferroelectricity is provided around the transistor 500.

[0326] 20B, an insulator 631 is provided on the top surface of a portion of the conductor 610 located on the conductor 540b functioning as a plug and the insulator 581. As an example, the insulator 631 can be a dielectric material that can have ferroelectricity and can be used for the insulator 520 in FIG.

[0327] In addition, a conductor 620 is provided on the upper surface of insulator 631, and an insulator 640 and an insulator 650 are provided in order on the upper surfaces of insulator 581, conductor 612, conductor 620, and a partial region of insulator 631.

[0328] Therefore, with the configuration shown in FIG. 20B, a ferroelectric capacitor can be provided between the conductor 610 and the conductor 620.

[0329] Note that the insulator 631 may have a laminated structure of two or more layers, similar to the insulator 520 shown in FIGS. 17B and 17C.

[0330] Furthermore, the respective configurations of the transistor and ferroelectric capacitor shown in FIGS. 20A and 20B can be applied to, for example, the transistor M1 and capacitor FC1 described in the first embodiment.

[0331] By applying the structure described in this embodiment to a semiconductor device including a transistor having an oxide semiconductor, fluctuations in electrical characteristics of the transistor can be suppressed and reliability can be improved. Alternatively, miniaturization or high integration of a semiconductor device including a transistor having an oxide semiconductor can be achieved.

[0332] Note that this embodiment mode can be appropriately combined with other embodiment modes described in this specification.

[0333] (Embodiment 3) In this embodiment, a metal oxide (hereinafter also referred to as an oxide semiconductor) that can be used for the OS transistor described in the above embodiment will be described.

[0334] The metal oxide preferably contains at least indium or zinc. It is particularly preferable that it contains indium and zinc. It is also preferable that it contains aluminum, gallium, yttrium, tin, or the like in addition to these. It may also contain one or more elements selected from boron, silicon, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, magnesium, cobalt, and the like.

[0335] <Classification of crystal structures> First, classification of crystal structures in oxide semiconductors will be described with reference to Fig. 21A. Fig. 21A is a diagram for explaining classification of crystal structures of oxide semiconductors, typically IGZO (a metal oxide containing In, Ga, and Zn).

[0336] As shown in FIG. 21A, oxide semiconductors are broadly classified into "Amorphous," "Crystalline," and "Crystal." "Amorphous" includes completely amorphous. "Crystalline" includes c-axis-aligned crystalline (CAAC), nanocrystalline (nc), and cloud-aligned composite (CAC). The "Crystalline" classification excludes single crystal, polycrystal, and completely amorphous (in the figure, "excluding single crystal and polycrystal" is added). "Crystal" includes single crystal and polycrystal.

[0337] The structure within the bold frame in Figure 21A is an intermediate state between "Amorphous" and "Crystal" and belongs to a new boundary region (New crystalline phase). In other words, this structure can be said to be completely different from the energetically unstable "Amorphous" and "Crystal."

[0338] The crystalline structure of a film or substrate can be evaluated using X-ray diffraction (XRD) spectroscopy. Figure 21B shows the XRD spectrum obtained by GIXD (Grazing-Incidence XRD) measurement of a CAAC-IGZO film classified as "Crystalline." The GIXD method is also known as the thin-film method or the Seemann-Bohlin method. Hereinafter, the XRD spectrum obtained by GIXD measurement shown in Figure 21B will be simply referred to as the XRD spectrum. The composition of the CAAC-IGZO film shown in Figure 21B is approximately In:Ga:Zn = 4:2:3 [atomic ratio]. The thickness of the CAAC-IGZO film shown in Figure 21B is 500 nm.

[0339] As shown in Figure 21B, a clear peak indicating crystallinity is detected in the XRD spectrum of the CAAC-IGZO film. Specifically, a peak indicating c-axis orientation is detected near 2θ = 31° in the XRD spectrum of the CAAC-IGZO film. As shown in Figure 21B, the peak near 2θ = 31° is asymmetric with respect to the angle at which the peak intensity is detected.

[0340] The crystalline structure of a film or substrate can be evaluated by the diffraction pattern (also called the nanobeam electron diffraction pattern) observed by nanobeam electron diffraction (NBED). The diffraction pattern of the CAAC-IGZO film is shown in Figure 21C. Figure 21C shows a diffraction pattern observed by NBED, in which an electron beam is incident parallel to the substrate. The composition of the CAAC-IGZO film shown in Figure 21C is approximately In:Ga:Zn = 4:2:3 [atomic ratio]. In the nanobeam electron diffraction method, electron diffraction is performed using a probe diameter of 1 nm.

[0341] As shown in FIG. 21C, multiple spots indicating c-axis orientation are observed in the diffraction pattern of the CAAC-IGZO film.

[0342] <<Structure of oxide semiconductor>> Note that oxide semiconductors may be classified differently from those shown in FIG. 21A when focusing on their crystal structures. For example, oxide semiconductors are divided into single-crystal oxide semiconductors and other non-single-crystal oxide semiconductors. Examples of non-single-crystal oxide semiconductors include the above-mentioned CAAC-OS and nc-OS. Non-single-crystal oxide semiconductors include polycrystalline oxide semiconductors, amorphous-like oxide semiconductors (a-like OSs), amorphous oxide semiconductors, and the like.

[0343] Here, the above-mentioned CAAC-OS, nc-OS, and a-like OS will be described in detail.

[0344] [CAAC-OS] CAAC-OS is an oxide semiconductor having multiple crystalline regions, each with its c-axis aligned in a specific direction. The specific direction can be the thickness direction of the CAAC-OS film, the normal direction to the surface on which the CAAC-OS film is formed, or the normal direction to the surface of the CAAC-OS film. A crystalline region is a region with periodic atomic arrangement. If the atomic arrangement is considered as a lattice arrangement, a crystalline region can also be a region with a uniform lattice arrangement. Furthermore, CAAC-OS has a region where multiple crystalline regions are connected in the ab-plane direction, and the region may have distortion. Note that distortion refers to a location where the lattice arrangement changes between a region with a uniform lattice arrangement and a region with a different uniform lattice arrangement in the region where multiple crystalline regions are connected. In other words, CAAC-OS is an oxide semiconductor with a c-axis aligned but no clear orientation in the ab-plane direction.

[0345] Each of the multiple crystalline regions is composed of one or more minute crystals (crystals with a maximum diameter of less than 10 nm). When a crystalline region is composed of one minute crystal, the maximum diameter of the crystalline region is less than 10 nm. When a crystalline region is composed of many minute crystals, the size of the crystalline region may be several tens of nm.

[0346] In an In-M-Zn oxide (wherein M is one or more elements selected from aluminum, gallium, yttrium, tin, titanium, etc.), the CAAC-OS tends to have a layered crystal structure (also referred to as a layered structure) in which a layer containing indium (In) and oxygen (hereinafter referred to as an In layer) and a layer containing M, zinc (Zn), and oxygen (hereinafter referred to as an (M, Zn) layer) are stacked. Note that indium and the element M are mutually substituted. Therefore, the (M, Zn) layer may contain indium. The In layer may contain M. The In layer may contain Zn. The layered structure is observed as a lattice image in a high-resolution TEM image, for example.

[0347] When the CAAC-OS film is subjected to structural analysis using, for example, an XRD apparatus, a peak indicating c-axis orientation is detected at or near 2θ=31° in out-of-plane XRD measurement using θ / 2θ scan. Note that the position of the peak indicating c-axis orientation (2θ value) may vary depending on the type and composition of the metallic elements constituting the CAAC-OS.

[0348] Furthermore, for example, in the electron diffraction pattern of the CAAC-OS film, multiple bright spots are observed, and the spots are observed at positions that are point-symmetric with respect to the spot of the incident electron beam that has passed through the sample (also called the direct spot).

[0349] When the crystalline region is observed from the specific direction, the lattice arrangement within the crystalline region is basically a hexagonal lattice, but the unit cell is not necessarily a regular hexagon and may be non-regular hexagonal. The distortion may also have a pentagonal, heptagonal, or other lattice arrangement. In the CAAC-OS, no clear grain boundaries are observed even near the distortion. This indicates that the formation of grain boundaries is suppressed by the distortion of the lattice arrangement. This is thought to be because the CAAC-OS can tolerate distortion due to the lack of close-packed oxygen atom arrangement in the ab-plane direction and the change in interatomic bond distance caused by metal atom substitution.

[0350] A crystal structure with clear grain boundaries is called polycrystalline. Grain boundaries act as recombination centers, trapping carriers and potentially causing a decrease in the on-state current and field-effect mobility of a transistor. Therefore, CAAC-OS, which lacks clear grain boundaries, is one of the crystalline oxides with a crystal structure suitable for use in the semiconductor layer of a transistor. Zn is preferred for use in CAAC-OS. For example, In-Zn oxide and In-Ga-Zn oxide are suitable because they can suppress the generation of grain boundaries more effectively than In oxide.

[0351] CAAC-OS is an oxide semiconductor with high crystallinity and no clear crystal grain boundaries. Therefore, it can be said that the CAAC-OS is less susceptible to a decrease in electron mobility due to crystal grain boundaries. Furthermore, since the crystallinity of an oxide semiconductor can be reduced by the inclusion of impurities or the formation of defects, the CAAC-OS can be said to be an oxide semiconductor with few impurities and defects (such as oxygen vacancies). Therefore, oxide semiconductors with CAAC-OS have stable physical properties. Therefore, oxide semiconductors with CAAC-OS are heat-resistant and highly reliable. Furthermore, the CAAC-OS is stable even under high temperatures (so-called thermal budget) during the manufacturing process. Therefore, using a CAAC-OS for an OS transistor can increase the flexibility of the manufacturing process.

[0352] [nc-OS] The nc-OS has periodic atomic arrangement in a microscopic region (e.g., a region of 1 nm to 10 nm, particularly a region of 1 nm to 3 nm). In other words, the nc-OS has microcrystalline structures. The size of the microcrystalline structures is, for example, 1 nm to 10 nm, particularly 1 nm to 3 nm, and therefore the microcrystalline structures are also called nanocrystalline structures. Furthermore, the nc-OS exhibits no regularity in the crystal orientation between different nanocrystalline structures. Therefore, the entire film lacks orientation. Therefore, depending on the analytical method, the nc-OS may be indistinguishable from an a-like OS or an amorphous oxide semiconductor. For example, when a structural analysis of an nc-OS film is performed using an XRD apparatus, no peaks indicating crystallinity are detected in out-of-plane XRD measurements using θ / 2θ scanning. Furthermore, when an nc-OS film is subjected to electron diffraction (also known as selected-area electron diffraction) using an electron beam with a probe diameter larger than that of nanocrystalline structures (e.g., 50 nm or larger), a halo-like diffraction pattern is observed. On the other hand, when electron diffraction (also called nanobeam electron diffraction) is performed on an nc-OS film using an electron beam with a probe diameter close to or smaller than the size of the nanocrystals (for example, 1 nm to 30 nm), an electron diffraction pattern can be obtained in which multiple spots are observed within a ring-shaped region centered on the direct spot.

[0353] [a-like OS] The a-like OS is an oxide semiconductor having a structure between the nc-OS and the amorphous oxide semiconductor. The a-like OS has a pore or low-density region. That is, the a-like OS has lower crystallinity than the nc-OS and CAAC-OS. Furthermore, the a-like OS has a higher hydrogen concentration in the film than the nc-OS and CAAC-OS.

[0354] <<Oxide semiconductor structure>> Next, the above-mentioned CAC-OS will be described in detail, which relates to the material composition.

[0355] [CAC-OS] CAC-OS is a material structure in which elements constituting a metal oxide are unevenly distributed in a size range of 0.5 nm to 10 nm, preferably 1 nm to 3 nm, or a similar size range. Hereinafter, a metal oxide in which one or more metal elements are unevenly distributed and the regions containing the metal elements are mixed in a size range of 0.5 nm to 10 nm, preferably 1 nm to 3 nm, or a similar size range, is also referred to as a mosaic or patch state.

[0356] Furthermore, CAC-OS has a mosaic structure in which the material is separated into first and second regions, and the first regions are distributed throughout the film (hereinafter also referred to as a cloud structure). That is, CAC-OS is a composite metal oxide having a structure in which the first and second regions are mixed.

[0357] Here, the atomic ratios of In, Ga, and Zn to the metal elements constituting the CAC-OS in the In-Ga-Zn oxide are denoted as [In], [Ga], and [Zn], respectively. For example, in the CAC-OS in the In-Ga-Zn oxide, the first region is a region where [In] is larger than [In] in the composition of the CAC-OS film. The second region is a region where [Ga] is larger than [Ga] in the composition of the CAC-OS film. Alternatively, for example, the first region is a region where [In] is larger than [In] in the second region and [Ga] is smaller than [Ga] in the second region. The second region is a region where [Ga] is larger than [Ga] in the first region and [In] is smaller than [In] in the first region.

[0358] Specifically, the first region is a region whose main component is indium oxide, indium zinc oxide, or the like. The second region is a region whose main component is gallium oxide, gallium zinc oxide, or the like. In other words, the first region can be rephrased as a region whose main component is In. The second region can be rephrased as a region whose main component is Ga.

[0359] It should be noted that there are cases where a clear boundary between the first region and the second region cannot be observed.

[0360] For example, in the case of CAC-OS in In-Ga-Zn oxide, EDX mapping obtained using EDX (Energy Dispersive X-ray spectroscopy) confirms that the CAC-OS has a structure in which a region mainly composed of In (first region) and a region mainly composed of Ga (second region) are unevenly distributed and mixed.

[0361] When CAC-OS is used in a transistor, the conductivity due to the first region and the insulating property due to the second region act in a complementary manner, thereby providing the CAC-OS with a switching function (the ability to turn on and off). In other words, CAC-OS has a conductive function in part of the material and an insulating function in part of the material, and the material as a whole functions as a semiconductor. By separating the conductive function from the insulating function, both functions can be maximized. Therefore, by using CAC-OS in a transistor, a high on-current (I on ), high field-effect mobility (μ), and good switching behavior can be achieved.

[0362] Oxide semiconductors have a variety of structures, each with different characteristics. The oxide semiconductor of one embodiment of the present invention may include two or more of an amorphous oxide semiconductor, a polycrystalline oxide semiconductor, an a-like OS, a CAC-OS, an nc-OS, and a CAAC-OS.

[0363] <Transistors containing oxide semiconductors> Next, a case where the oxide semiconductor is used in a transistor will be described.

[0364] By using the oxide semiconductor for a transistor, a transistor with high field-effect mobility and high reliability can be realized.

[0365] For the transistor, an oxide semiconductor with a low carrier concentration is preferably used. For example, the carrier concentration of the oxide semiconductor is 1×10 17 cm -3 Less than 1 × 10 15 cm -3 or less, more preferably 1 × 10 13 cm -3 Less than 1×10, more preferably 11 cm -3 or less, more preferably 1 × 10 10 cm -3 Less than 1 x 10 -9 cm-3 The above is the case. Note that in order to reduce the carrier concentration of an oxide semiconductor film, the impurity concentration in the oxide semiconductor film may be reduced to reduce the density of defect states. In this specification and the like, a semiconductor having a low impurity concentration and a low density of defect states is referred to as a highly purified intrinsic or substantially highly purified intrinsic oxide semiconductor. Note that an oxide semiconductor having a low carrier concentration may also be referred to as a highly purified intrinsic or substantially highly purified intrinsic oxide semiconductor.

[0366] Furthermore, a highly purified intrinsic or substantially highly purified intrinsic oxide semiconductor film has a low density of defect states, and therefore the density of trap states may also be low.

[0367] Furthermore, charges trapped in the trap states of an oxide semiconductor take a long time to disappear and may behave like fixed charges. Therefore, a transistor in which a channel formation region is formed in an oxide semiconductor with a high density of trap states may have unstable electrical characteristics.

[0368] Therefore, in order to stabilize the electrical characteristics of a transistor, it is effective to reduce the impurity concentration in the oxide semiconductor. Furthermore, in order to reduce the impurity concentration in the oxide semiconductor, it is preferable to also reduce the impurity concentration in the adjacent film. Examples of impurities include hydrogen, nitrogen, alkali metals, alkaline earth metals, iron, nickel, and silicon.

[0369] <Impurities> Here, the influence of each impurity in an oxide semiconductor will be described.

[0370] When an oxide semiconductor contains silicon or carbon, which is one of the Group 14 elements, defect levels are formed in the oxide semiconductor. Therefore, the concentrations of silicon and carbon in the oxide semiconductor and those near the interface with the oxide semiconductor (concentrations obtained by secondary ion mass spectrometry (SIMS)) are calculated to be 2×10 18 atoms / cm 3 Less than or equal to 2 x 10 17atoms / cm 3 The following applies.

[0371] Furthermore, when an oxide semiconductor contains an alkali metal or alkaline earth metal, defect levels may be formed and carriers may be generated. Therefore, a transistor using an oxide semiconductor containing an alkali metal or alkaline earth metal is likely to have normally-on characteristics. For this reason, when the concentration of the alkali metal or alkaline earth metal in the oxide semiconductor obtained by SIMS is 1×10 18 atoms / cm 3 Less than or equal to 2 x 10 16 atoms / cm 3 Do the following:

[0372] Furthermore, when nitrogen is contained in an oxide semiconductor, electrons serving as carriers are generated, the carrier concentration increases, and the semiconductor is likely to become n-type. As a result, a transistor using an oxide semiconductor containing nitrogen as a semiconductor tends to have normally-on characteristics. Alternatively, when nitrogen is contained in an oxide semiconductor, trap states may be formed. As a result, the electrical characteristics of the transistor may become unstable. For this reason, the nitrogen concentration in the oxide semiconductor obtained by SIMS is set to 5×10 19 atoms / cm 3 Less than 5 x 10 18 atoms / cm 3 Less than 1×10, more preferably 18 atoms / cm 3 Less than 5 × 10, more preferably 17 atoms / cm 3 Do the following:

[0373] Furthermore, hydrogen contained in an oxide semiconductor may react with oxygen bonded to a metal atom to form water, which may form an oxygen vacancy. When hydrogen enters the oxygen vacancy, electrons serving as carriers may be generated. Furthermore, some of the hydrogen may bond with oxygen bonded to a metal atom to generate electrons serving as carriers. Therefore, a transistor using an oxide semiconductor containing hydrogen is likely to have normally-on characteristics. For this reason, it is preferable to reduce the amount of hydrogen in the oxide semiconductor as much as possible. Specifically, the hydrogen concentration in an oxide semiconductor measured by SIMS is 1×10 20 atoms / cm 3 Less than 1 x 10 19 atoms / cm 3 less than 5 × 10 18 atoms / cm 3 less than 1×10 18 atoms / cm 3 Make it less than.

[0374] When an oxide semiconductor with sufficiently reduced impurities is used for a channel formation region of a transistor, stable electrical characteristics can be obtained.

[0375] Note that this embodiment mode can be appropriately combined with other embodiment modes described in this specification.

[0376] (Fourth embodiment) In this embodiment mode, an example in which the semiconductor device functioning as a control circuit for a secondary battery described in the above embodiment mode is used as an electronic component will be described with reference to FIG.

[0377] In this embodiment, an example of a system-on-chip 1204 on which a semiconductor device is mounted is shown with reference to Fig. 22. A plurality of circuits (systems) are mounted on the system-on-chip 1204. A technology for integrating a plurality of circuits (systems) on a single chip in this way is sometimes called a system-on-chip (SoC).

[0378] Fig. 22 shows an example in which multiple chips are provided on a printed circuit board (PCB) 1203. In Fig. 22, a chip 1201 is provided on the printed circuit board 1203. The chip 1201 is provided with a semiconductor device that functions as a control circuit for a secondary battery. A plurality of bumps 1202 are provided on the back surface of the chip 1201, and are connected to the printed circuit board 1203.

[0379] By providing a semiconductor device that functions as a control circuit for a secondary battery according to one embodiment of the present invention, chips in electronic components can be miniaturized.

[0380] Furthermore, by providing a semiconductor device that functions as a control circuit for a secondary battery according to one embodiment of the present invention, chip integration is possible, and therefore the volume occupied by the control circuit can be reduced in mobile terminals and various other electronic devices, leading to miniaturization of the electronic devices. Furthermore, miniaturization of the control circuit can also increase the volume occupied by the secondary battery. This allows the duration of the storage battery to be extended. Furthermore, miniaturization of the control circuit can sometimes reduce power consumption.

[0381] An integrated circuit 1223 is preferably provided as a second chip on the printed circuit board 1203. The integrated circuit 1223 has a function of providing control signals, power, and the like to the chip 1201.

[0382] The various chips provided on the printed circuit board 1203 may include storage devices such as a DRAM 1221 and a flash memory 1222. The printed circuit board 1203 may also be provided with a chip 1225 that has a function of performing wireless communication.

[0383] The integrated circuit 1223 may also have a function of performing image processing or product-sum operations.

[0384] The integrated circuit 1223 may also include one or both of an A / D (analog / digital) conversion circuit and a D / A (digital / analog) conversion circuit.

[0385] This embodiment mode can be combined with the descriptions of other embodiment modes as appropriate.

[0386] (Embodiment 5) In this embodiment mode, a configuration of a power storage device to which the electronic component including the control circuit for a secondary battery described in the above embodiment mode can be applied will be described.

[0387] [Cylindrical secondary battery] An example of a cylindrical secondary battery will be described with reference to Fig. 23A. As shown in Fig. 23A, a cylindrical secondary battery 400 has a positive electrode cap (battery lid) 401 on the top surface, and a battery can (external can) 402 on the side and bottom surfaces. The positive electrode cap 401 and the battery can (external can) 402 are insulated by a gasket (insulating packing) 410.

[0388] Fig. 23B is a diagram showing a cross section of a cylindrical secondary battery. The cylindrical secondary battery shown in Fig. 23B has a positive electrode cap (battery lid) 801 on the top surface and a battery can (external can) 802 on the side and bottom surfaces. The positive electrode cap and battery can (external can) 802 are insulated by a gasket (insulating packing) 810.

[0389] A battery element is provided inside a hollow cylindrical battery can 802, in which a strip-shaped positive electrode 804 and a negative electrode 806 are wound with a separator 805 sandwiched between them. Although not shown, the battery element is wound around a center pin. One end of the battery can 802 is closed and the other end is open. The battery can 802 can be made of a metal, such as nickel, aluminum, or titanium, or an alloy of these metals or an alloy of these metals with other metals (e.g., stainless steel), which is corrosion-resistant to the electrolyte. To prevent corrosion by the electrolyte, the battery can 802 is preferably coated with nickel, aluminum, or the like. Inside the battery can 802, the wound battery element, in which the positive electrode, negative electrode, and separator are wound, is sandwiched between a pair of opposing insulating plates 808 and 809. A nonaqueous electrolyte (not shown) is poured into the battery can 802, in which the battery element is provided. The nonaqueous electrolyte may be the same as that used in coin-type secondary batteries.

[0390] Because the positive and negative electrodes used in cylindrical storage batteries are wound, it is preferable to form active materials on both sides of the current collectors. A positive electrode terminal (positive electrode current collector lead) 803 is connected to the positive electrode 804, and a negative electrode terminal (negative electrode current collector lead) 807 is connected to the negative electrode 806. Both the positive electrode terminal 803 and the negative electrode terminal 807 can be made of a metal material such as aluminum. The positive electrode terminal 803 is resistance-welded to a safety valve mechanism 813, and the negative electrode terminal 807 is resistance-welded to the bottom of the battery can 802. The safety valve mechanism 813 is electrically connected to the positive electrode cap 801 via a PTC (Positive Temperature Coefficient) element 811. The safety valve mechanism 813 cuts off the electrical connection between the positive electrode cap 801 and the positive electrode 804 when the internal pressure of the battery exceeds a predetermined threshold. The PTC element 811 is a thermosensitive resistor whose resistance increases as the temperature rises, and the increased resistance limits the amount of current to prevent abnormal heat generation. Barium titanate (BaTiO3)-based semiconductor ceramics or the like can be used for the PTC element.

[0391] 23C illustrates an example of a power storage device 415. The power storage device 415 includes a plurality of secondary batteries 400. A positive electrode of each secondary battery is in contact with and electrically connected to a conductor 424 separated by an insulator 425. The conductor 424 is electrically connected to a control circuit 420 through a wiring 423. A negative electrode of each secondary battery is electrically connected to the control circuit 420 through a wiring 426. The control circuit described in the above embodiment can be used as the control circuit 420.

[0392] 23D shows an example of a power storage device 415. The power storage device 415 has a plurality of secondary batteries 400, which are sandwiched between a conductive plate 433 and a conductive plate 434. The plurality of secondary batteries 400 are electrically connected to the conductive plate 433 and the conductive plate 434 by wiring 436. The plurality of secondary batteries 400 may be connected in parallel, in series, or in parallel and then further connected in series. By configuring the power storage device 415 to have a plurality of secondary batteries 400, a large amount of power can be extracted.

[0393] A temperature control device may be provided between the multiple secondary batteries 400. When the secondary batteries 400 are overheated, they can be cooled by the temperature control device, and when the secondary batteries 400 are too cold, they can be heated by the temperature control device. This makes it difficult for the performance of the power storage device 415 to be affected by the outside temperature.

[0394] 23D, the power storage device 415 is electrically connected to a control circuit 420 through wiring 421 and wiring 422. The control circuit for the secondary battery described in the above embodiment can be used as the control circuit 420. The wiring 421 is electrically connected to positive electrodes of the plurality of secondary batteries 400 through a conductive plate 433, and the wiring 422 is electrically connected to negative electrodes of the plurality of secondary batteries 400 through a conductive plate 434.

[0395] Alternatively, a secondary battery 913 may be provided having a wound body 950a as shown in FIGS. 24A to 24C. The wound body 950a shown in FIG. 24A has a negative electrode 931, a positive electrode 932, and a separator 933. The negative electrode 931 has a negative electrode active material layer 931a. The positive electrode 932 has a positive electrode active material layer 932a. The separator 933 has a width greater than that of the negative electrode active material layer 931a and the positive electrode active material layer 932a, and is wound so as to overlap with the negative electrode active material layer 931a and the positive electrode active material layer 932a. From the standpoint of safety, it is preferable that the width of the negative electrode active material layer 931a is greater than that of the positive electrode active material layer 932a. A wound body 950a having such a shape is preferable because of its high safety and productivity.

[0396] 24B, negative electrode 931 is electrically connected to terminal 951. Terminal 951 is electrically connected to terminal 911a. Positive electrode 932 is electrically connected to terminal 952. Terminal 952 is electrically connected to terminal 911b.

[0397] 24C, wound body 950a and the electrolyte are covered with casing 930 to form secondary battery 913. It is preferable that casing 930 is provided with a safety valve, an overcurrent protection element, and the like.

[0398] 24B, the secondary battery 913 may have a plurality of wound bodies 950a. By using a plurality of wound bodies 950a, the secondary battery 913 can have a larger charge / discharge capacity.

[0399] [Secondary battery pack] Next, an example of a power storage device of one embodiment of the present invention will be described with reference to FIG.

[0400] 25A is a diagram showing the appearance of secondary battery pack 531. FIG. 25B is a diagram illustrating the configuration of secondary battery pack 531. Secondary battery pack 531 has circuit board 501 and secondary battery 513. Label 509 is attached to secondary battery 513. Circuit board 501 is fixed with sticker 515. Secondary battery pack 531 also has antenna 517.

[0401] The circuit board 501 has a control circuit 590. The control circuit shown in the above embodiment can be used as the control circuit 590. For example, as shown in FIG. 25B , the control circuit 590 is provided on the circuit board 501. The circuit board 501 is also electrically connected to a terminal 511. The circuit board 501 is also electrically connected to an antenna 517, one 551 of a positive electrode lead and a negative electrode lead of a secondary battery 513, and the other 555 of the positive electrode lead and the negative electrode lead.

[0402] 25C , the semiconductor device may include a circuit system 590a provided on a circuit board 501 and a circuit system 590b electrically connected to the circuit board 501 via a terminal 511. For example, a part of a control circuit according to one embodiment of the present invention is provided in the circuit system 590a, and another part is provided in the circuit system 590b.

[0403] The antenna 517 is not limited to a coil shape, and may be, for example, a wire or plate shape. Also, antennas such as a planar antenna, an aperture antenna, a traveling wave antenna, an EH antenna, a magnetic field antenna, and a dielectric antenna may be used. Alternatively, the antenna 517 may be a flat conductor. This flat conductor can function as one of the conductors for electric field coupling. In other words, the antenna 517 may function as one of the two conductors of a capacitor. This allows power to be exchanged not only by electromagnetic fields and magnetic fields, but also by electric fields.

[0404] The secondary battery pack 531 has a layer 519 between the antenna 517 and the secondary battery 513. The layer 519 has a function of, for example, shielding an electromagnetic field caused by the secondary battery 513. The layer 519 can be made of, for example, a magnetic material.

[0405] The secondary battery 513 is formed by stacking a negative electrode and a positive electrode with a separator sandwiched between them, and then winding the laminate sheet.

[0406] This embodiment mode can be combined with the descriptions of other embodiment modes as appropriate.

[0407] (Embodiment 6) In this embodiment, an example in which a power storage device according to one embodiment of the present invention is mounted on a vehicle will be described. Examples of vehicles include automobiles, motorcycles, and bicycles.

[0408] By installing a power storage device in a vehicle, next-generation clean energy vehicles such as hybrid vehicles (HVs), electric vehicles (EVs), and plug-in hybrid vehicles (PHVs) can be realized.

[0409] 26A illustrates an example of a vehicle using a power storage device according to one embodiment of the present invention. An automobile 8400 illustrated in FIG. 26A is an electric automobile using an electric motor as a power source for traveling. Alternatively, it is a hybrid automobile that can appropriately select and use an electric motor or an engine as a power source for traveling. By using one embodiment of the present invention, a vehicle with a long cruising distance can be realized. The automobile 8400 includes a power storage device. The power storage device not only drives the electric motor 8406 but also supplies power to light-emitting devices such as a headlight 8401 and an interior light (not shown).

[0410] The power storage device can supply power to display devices such as a speedometer and a tachometer included in the automobile 8400. The power storage device can also supply power to a navigation system included in the automobile 8400.

[0411] The automobile 8500 shown in FIG. 26B can charge the power storage device 8024 of the automobile 8500 by receiving power supply from an external charging facility using a plug-in method, a contactless power supply method, or the like. FIG. 26B shows a state in which charging is being performed from a ground-mounted charging device 8021 to the power storage device 8024 mounted on the automobile 8500 via a cable 8022. The charging method, connector specifications, and the like may be appropriately determined using a predetermined method such as CHAdeMO (registered trademark) or Combo. The charging device 8021 may be a charging station installed in a commercial facility or a household power source. For example, plug-in technology can be used to charge the power storage device 8024 mounted on the automobile 8500 using external power supply. Charging can be performed by converting AC power to DC power using a conversion device such as an AC-DC converter.

[0412] Although not shown, a power receiving device can be mounted on a vehicle and can be charged by receiving power contactlessly from a ground-based power transmitting device. In the case of this contactless power supply method, by incorporating a power transmitting device into a road, an exterior wall, or the like, charging can be performed not only while the vehicle is stopped but also while the vehicle is moving. This contactless power supply method can also be used to transmit and receive power between vehicles. Furthermore, a solar cell can be provided on the exterior of the vehicle, and the power storage device can be charged while the vehicle is stopped, moving, etc. For such contactless power supply, an electromagnetic induction method, a magnetic field resonance method, etc. can be used.

[0413] 26C is an example of a two-wheeled vehicle including a power storage device of one embodiment of the present invention. A scooter 8600 shown in FIG. 26C includes a power storage device 8602, a side mirror 8601, and a turn signal light 8603. The power storage device 8602 can supply electricity to the turn signal light 8603.

[0414] 26C, the power storage device 8602 can be stored in the under-seat storage 8604. The power storage device 8602 can be stored in the under-seat storage 8604 even if the under-seat storage 8604 is small.

[0415] 27A is an example of an electric bicycle using the power storage device of one embodiment of the present invention. The power storage device of one embodiment of the present invention can be applied to an electric bicycle 8700 shown in FIG. 27A. The power storage device of one embodiment of the present invention includes, for example, a plurality of storage batteries, a protection circuit, and a neural network.

[0416] The electric bicycle 8700 includes a power storage device 8702. The power storage device 8702 can supply electricity to a motor that assists a rider. The power storage device 8702 is portable and is shown in a state removed from the bicycle in FIG. 27B . The power storage device 8702 includes a plurality of built-in storage batteries 8701, which are included in the power storage device of one embodiment of the present invention, and the remaining battery charge and the like can be displayed on a display unit 8703. The power storage device 8702 also includes a control circuit 8704 of one embodiment of the present invention. The control circuit 8704 is electrically connected to the positive and negative electrodes of the storage batteries 8701. The battery control circuit described in the above embodiment can be used as the control circuit 8704.

[0417] This embodiment mode can be combined with the descriptions of other embodiment modes as appropriate.

[0418] (Embodiment 7) In this embodiment, an example in which the power storage device described in the above embodiment is mounted on an electronic device will be described.

[0419] Next, FIGS. 28A and 28B show an example of a foldable tablet terminal (including a clamshell terminal). The tablet terminal 9600 shown in FIGS. 28A and 28B includes a housing 9630a, a housing 9630b, a movable portion 9640 connecting the housings 9630a and 9630b, a display unit 9631, a display mode selector switch 9626, a power switch 9627, a power saving mode selector switch 9625, a fastener 9629, and an operation switch 9628. Using a flexible panel for the display unit 9631 allows the tablet terminal to have a larger display area. FIG. 28A shows the tablet terminal 9600 in an open state, and FIG. 28B shows the tablet terminal 9600 in a closed state.

[0420] The tablet terminal 9600 also includes a power storage unit 9635 inside the housing 9630a and the housing 9630b. The power storage unit 9635 passes through the movable portion 9640 and is provided across the housing 9630a and the housing 9630b.

[0421] A part of the display portion 9631 can be a touch panel area, and data can be input by touching displayed operation keys. Furthermore, keyboard buttons can be displayed on the display portion 9631 by touching a position on the touch panel where a keyboard display switch button is displayed with a finger, a stylus, or the like.

[0422] Furthermore, a display mode switch 9626 can switch the display orientation between portrait and landscape, and can select between black and white and color display. A power saving mode switch 9625 can optimize the display brightness according to the amount of external light during use detected by an optical sensor built into the tablet terminal 9600. The tablet terminal may be equipped with not only an optical sensor but also other detection devices such as a gyroscope, an acceleration sensor, or other sensors that detect tilt.

[0423] 28B shows the tablet terminal in a closed state, which includes a housing 9630, a solar cell 9633, and the power storage device of one embodiment of the present invention. The power storage device includes a control circuit 9634 and a power storage unit 9635. The battery control circuit described in the above embodiment can be used for the control circuit 9634.

[0424] The tablet terminal 9600 can be folded in half, so that the housing 9630a and the housing 9630b overlap each other when not in use. By folding, the display portion 9631 can be protected, thereby improving durability of the tablet terminal 9600.

[0425] In addition, the tablet terminals shown in Figures 28A and 28B can have functions such as displaying various information (still images, videos, text images, etc.), displaying a calendar, date or time on the display unit, a touch input function for touch input operations or editing information displayed on the display unit, and controlling processing using various software (programs).

[0426] A solar cell 9633 attached to the surface of the tablet terminal can supply power to a touch panel, a display unit, a video signal processor, etc. The solar cell 9633 can be provided on one or both surfaces of the housing 9630, and can be configured to efficiently charge the power storage unit 9635.

[0427] 28A and 28B illustrate a configuration in which a control circuit using the battery control circuit described in the above embodiment is applied to a foldable tablet terminal. However, other configurations may be used. For example, as illustrated in FIG. 28C, the present invention may be applied to a notebook personal computer, which is a clamshell terminal. FIG. 28C illustrates a notebook personal computer 9601 including a display portion 9631 in a housing 9630a and a keyboard portion 9650 in a housing 9630b. The notebook personal computer 9601 includes the control circuit 9634 described in FIGS. 28A and 28B and a power storage unit 9635. The battery control circuit described in the above embodiment can be used for the control circuit 9634.

[0428] FIG. 29 illustrates an example of another electronic device. In FIG. 29, a display device 8000 is an example of an electronic device incorporating the power storage device of one embodiment of the present invention. Specifically, the display device 8000 corresponds to a display device for receiving TV broadcasts and includes a housing 8001, a display portion 8002, a speaker portion 8003, a secondary battery 8004, and the like. A detection system according to one embodiment of the present invention is provided inside the housing 8001. The display device 8000 can receive power from a commercial power source or can use power stored in the secondary battery 8004.

[0429] The display unit 8002 can be a liquid crystal display device, a light-emitting device having a light-emitting element such as an organic EL element in each pixel, an electrophoretic display device, a semiconductor display device such as a DMD (Digital Micromirror Device), a PDP (Plasma Display Panel), or an FED (Field Emission Display).

[0430] The voice input device 8005 also uses a secondary battery. The voice input device 8005 includes the power storage device described in the above embodiment. The voice input device 8005 includes a wireless communication element and a plurality of sensors including a microphone (optical sensors, temperature sensors, humidity sensors, air pressure sensors, illuminance sensors, motion sensors, and the like), and can control other devices, such as the power supply of the display device 8000 and the light intensity of the lighting device 8100, by verbal commands from the user. The voice input device 8005 can operate peripheral devices by voice and can serve as a substitute for a manual remote control.

[0431] In addition, the voice input device 8005 has wheels, mechanical moving means, etc., and moves in the direction in which the user's voice can be heard, accurately picks up commands using a built-in microphone, and displays the contents on the display unit 8008, or allows touch input operations on the display unit 8008.

[0432] The voice input device 8005 can also function as a charging dock for a mobile information terminal 8009 such as a smartphone. The mobile information terminal 8009 and the voice input device 8005 can exchange power via wired or wireless connections. The mobile information terminal 8009 does not need to be carried around indoors, and it is desirable to ensure the necessary capacity while avoiding deterioration due to load on the secondary battery. Therefore, it is desirable to use the voice input device 8005 to manage and maintain the secondary battery. Furthermore, the voice input device 8005 has a speaker 8007 and a microphone, so that hands-free conversation is possible even while the mobile information terminal 8009 is charging. Furthermore, when the capacity of the secondary battery of the voice input device 8005 decreases, it can be moved in the direction of the arrow and wirelessly charged from a charging module 8010 connected to an external power source.

[0433] The voice input device 8005 may be placed on a stand. The voice input device 8005 may be provided with wheels, mechanical moving means, or the like so that it can be moved to a desired position, or the voice input device 8005 may be fixed to a desired position, for example, on the floor, without being provided with a stand, wheels, or the like.

[0434] The display device includes all display devices for displaying information, such as those for receiving TV broadcasts, those for personal computers, and those for displaying advertisements.

[0435] 29, a stationary lighting device 8100 is an example of an electronic device that uses a secondary battery 8103 controlled by a microprocessor (including an APS) that controls charging. Specifically, the lighting device 8100 has a housing 8101, a light source 8102, a secondary battery 8103, and the like. FIG. 29 illustrates a case in which the secondary battery 8103 is provided inside a ceiling 8104 on which the housing 8101 and the light source 8102 are installed, but the secondary battery 8103 may be provided inside the housing 8101. The lighting device 8100 can receive power from a commercial power source, or can use power stored in the secondary battery 8103.

[0436] Although Figure 29 shows an example of a stationary lighting device 8100 installed on a ceiling 8104, the secondary battery 8103 can also be used in a stationary lighting device installed on a surface other than the ceiling 8104, such as a side wall 8105, a floor 8106, or a window 8107, or can also be used in a tabletop lighting device, etc.

[0437] Furthermore, an artificial light source that artificially obtains light using electric power can be used as the light source 8102. Specifically, examples of the artificial light source include discharge lamps such as incandescent lamps and fluorescent lamps, and light-emitting elements such as LEDs and organic EL elements.

[0438] In FIG. 29 , an air conditioner having an indoor unit 8200 and an outdoor unit 8204 is an example of an electronic device using a secondary battery 8203. Specifically, the indoor unit 8200 has a housing 8201, an air outlet 8202, a secondary battery 8203, and the like. Although FIG. 29 illustrates an example in which the secondary battery 8203 is provided in the indoor unit 8200, the secondary battery 8203 may be provided in the outdoor unit 8204. Alternatively, the secondary battery 8203 may be provided in both the indoor unit 8200 and the outdoor unit 8204. The air conditioner can receive power from a commercial power source or can use power stored in the secondary battery 8203.

[0439] 29, an electric refrigerator-freezer 8300 is an example of an electronic device using a secondary battery 8304. Specifically, the electric refrigerator-freezer 8300 includes a housing 8301, a refrigerator door 8302, a freezer door 8303, a secondary battery 8304, and the like. In FIG. 29, the secondary battery 8304 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 the secondary battery 8304.

[0440] Furthermore, by storing power in the secondary battery during time periods when electronic devices are not in use, particularly during time periods when the ratio of the amount of power actually used to the total amount of power that can be supplied by the commercial power supplier (referred to as the power usage rate) is low, it is possible to prevent the power usage rate from increasing outside of these time periods. For example, in the case of electric refrigerator-freezer 8300, power is stored in secondary battery 8304 during the night when the temperature is low and refrigerator door 8302 and freezer door 8303 are not opened or closed. Then, during the daytime when the temperature rises and refrigerator door 8302 and freezer door 8303 are opened and closed, secondary battery 8304 is used as an auxiliary power source, thereby making it possible to keep the daytime power usage rate low.

[0441] In addition to the electronic devices described above, the secondary battery can be mounted in various electronic devices. According to one embodiment of the present invention, the cycle characteristics of the secondary battery are improved. Therefore, by mounting 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.

[0442] 30A to 30E show examples in which the power storage device of one embodiment of the present invention is implemented in electronic devices. Examples of electronic devices to which the power storage device of one embodiment of the present invention is applied include television sets (also referred to as televisions or television receivers), computer monitors, digital cameras, digital video cameras, digital photo frames, mobile phones (also referred to as mobile phones or mobile phone devices), portable game consoles, personal digital assistants, sound players, and large game consoles such as pachinko machines.

[0443] 30A illustrates an example of a mobile phone. The mobile phone 7400 includes a display portion 7402 built into a housing 7401, operation buttons 7403, an external connection port 7404, a speaker 7405, a microphone 7406, and the like. Note that the mobile phone 7400 includes the power storage device of one embodiment of the present invention. The power storage device of one embodiment of the present invention includes, for example, a storage battery 7407 and the battery control circuit described in the above embodiment.

[0444] FIG. 30B shows a state in which the mobile phone 7400 is bent. When the mobile phone 7400 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, it is preferable to use a flexible storage battery as the storage battery 7407. FIG. 30C shows the bent state of the flexible storage battery. A control circuit 7408 is electrically connected to the storage battery. The battery control circuit described in the above embodiment can be used as the control circuit 7408.

[0445] Furthermore, a storage battery having a flexible shape can be incorporated along the curved surfaces of the interior or exterior walls of a house or building, or the interior or exterior of an automobile.

[0446] 30D 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 device of one embodiment of the present invention. The power storage device of one embodiment of the present invention includes, for example, a storage battery 7104 and the battery control circuit described in the above embodiment.

[0447] 30E shows an example of a wristwatch-type portable information terminal 7200. The portable information terminal 7200 includes a housing 7201, a display portion 7202, a band 7203, a buckle 7204, operation buttons 7205, an input / output terminal 7206, and the like.

[0448] The portable information terminal 7200 can execute various applications such as mobile phone calls, e-mail, document browsing and creation, music playback, internet communication, and computer games.

[0449] The display surface of the display portion 7202 is curved, and a display can be performed along the curved display surface. The display portion 7202 is also provided with a touch sensor, and can be operated by touching the screen with a finger, a stylus, or the like. For example, an application can be started by touching an icon 7207 displayed on the display portion 7202.

[0450] The operation button 7205 can be provided with various functions, such as time setting, power on / off operation, wireless communication on / off operation, silent mode activation / deactivation, power saving mode activation / deactivation, etc. For example, the functions of the operation button 7205 can be freely set by an operating system incorporated in the mobile information terminal 7200.

[0451] The mobile information terminal 7200 is also capable of performing standardized short-range wireless communication. For example, hands-free conversation is also possible by communicating with a wirelessly enabled headset.

[0452] The portable information terminal 7200 also includes an input / output terminal 7206, and can directly exchange data with other information terminals via a connector. Charging can also be performed via the input / output terminal 7206. Note that charging may be performed by wireless power supply without using the input / output terminal 7206.

[0453] The portable information terminal 7200 includes the power storage device of one embodiment of the present invention. The power storage device includes a storage battery and the battery control circuit described in the above embodiment.

[0454] The portable information terminal 7200 preferably has a sensor, such as a fingerprint sensor, a pulse sensor, a body temperature sensor, a touch sensor, a pressure sensor, an acceleration sensor, or the like.

[0455] This embodiment mode can be combined with the descriptions of other embodiment modes as appropriate.

[0456] (Embodiment 8) In this embodiment, an example in which a power storage device according to one embodiment of the present invention is mounted in an electronic device or a mobile object will be described.

[0457] 31A to 31D show examples of electronic devices incorporating the power storage device described in the previous embodiment. Examples of electronic devices that use a bendable secondary battery include television sets (also called televisions or television receivers), computer monitors, digital cameras, digital video cameras, digital photo frames, mobile phones (also called mobile phones or mobile phone sets), portable game machines, personal digital assistants, audio playback devices, and large game machines such as pachinko machines.

[0458] Furthermore, the power storage device can be applied to a moving object, typically an automobile. Examples of the automobile include next-generation clean energy automobiles such as hybrid vehicles (HVs), electric vehicles (EVs), and plug-in hybrid vehicles (PHVs). The power storage device can be applied as one of the power sources mounted in the automobile. The moving object is not limited to an automobile. Examples of the moving object include trains, monorails, ships, aircraft (helicopters, unmanned aerial vehicles (drones), airplanes, and rockets), electric bicycles, and electric motorcycles. The power storage device of one embodiment of the present invention can be applied to these moving objects.

[0459] The power storage device of this embodiment may also be applied to a ground-mounted charging device installed in a house, a charging station installed in a commercial facility, or the like.

[0460] 31A shows an example of a mobile phone. The mobile phone 2100 includes a display unit 2102 built into a housing 2101, as well as operation buttons 2103, an external connection port 2104, a speaker 2105, a microphone 2106, and the like. The mobile phone 2100 also includes a power storage device 2107.

[0461] The mobile phone 2100 can execute various applications such as mobile phone calls, e-mail, document browsing and creation, music playback, internet communication, and computer games.

[0462] The operation button 2103 can be provided with various functions, such as time setting, power on / off operation, wireless communication on / off operation, silent mode activation / deactivation, power saving mode activation / deactivation, etc. For example, the functions of the operation button 2103 can be freely set by an operating system built into the mobile phone 2100.

[0463] The mobile phone 2100 is also capable of performing standardized short-range wireless communication, and can also make hands-free calls by communicating with a wirelessly enabled headset, for example.

[0464] The mobile phone 2100 also has an external connection port 2104, which allows direct data exchange with other information terminals via a connector. Charging can also be performed via the external connection port 2104. Charging may also be performed by wireless power supply without using the external connection port 2104.

[0465] The mobile phone 2100 preferably has a sensor, such as a fingerprint sensor, a pulse sensor, a body temperature sensor, a touch sensor, a pressure sensor, an acceleration sensor, or the like.

[0466] 31B illustrates an unmanned aerial vehicle 2300 having multiple rotors 2302. The unmanned aerial vehicle 2300 is also called a drone. The unmanned aerial vehicle 2300 includes a power storage device 2301 which is one embodiment of the present invention, a camera 2303, and an antenna (not shown). The unmanned aerial vehicle 2300 can be remotely controlled via the antenna.

[0467] As shown in FIG. 31C, a power storage device 2602 including a plurality of power storage devices 2601 of one embodiment of the present invention may be mounted in a hybrid vehicle (HEV), an electric vehicle (EV), a plug-in hybrid vehicle (PHEV), or other electronic devices.

[0468] FIG. 31D shows an example of a vehicle equipped with a power storage device 2602. The vehicle 2603 is an electric vehicle that uses an electric motor as a power source for traveling. Alternatively, the vehicle 2603 is a hybrid vehicle that can select and use an electric motor or an engine as a power source for traveling. The vehicle 2603 that uses an electric motor has multiple ECUs (Electronic Control Units), and the ECUs perform engine control and the like. The ECUs include microcomputers. The ECUs are connected to a CAN (Controller Area Network) provided in the electric vehicle. CAN is one of the serial communication standards used as an in-vehicle LAN.

[0469] The power storage device can not only drive an electric motor (not shown) but also supply power to light-emitting devices such as headlights, room lights, etc. The power storage device can also supply power to display devices and semiconductor devices such as a speedometer, a tachometer, and a navigation system included in the vehicle 2603.

[0470] The vehicle 2603 can be charged by receiving power supply from an external charging facility to the power storage device of the power storage device 2602 by a plug-in method, a contactless power supply method, or the like.

[0471] FIG. 32A shows a state in which a vehicle 2603 is being charged via a cable from a ground-mounted charging device 2604. Charging may be performed using a predetermined charging method, connector specifications, or the like, such as CHAdeMO (registered trademark) or Combo. For example, plug-in technology can be used to charge a power storage device 2602 mounted on the vehicle 2603 using an external power supply. Charging can be performed by converting AC power to DC power via a conversion device such as an AC-DC converter. The charging device 2604 may be installed in a home as shown in FIG. 32A, or may be a charging station installed in a commercial facility.

[0472] Although not shown, a power receiving device can be mounted on a vehicle and can be charged by receiving power contactlessly from a ground-based power transmitting device. In the case of this contactless power supply method, by incorporating a power transmitting device into a road, an exterior wall, or the like, charging can be performed not only while the vehicle is stopped but also while the vehicle is moving. This contactless power supply method can also be used to transmit and receive power between vehicles. Furthermore, a solar cell can be provided on the exterior of the vehicle, and the power storage device can be charged while the vehicle is stopped, moving, etc. For such contactless power supply, an electromagnetic induction method, a magnetic field resonance method, etc. can be used.

[0473] Next, an example of a power storage device of one embodiment of the present invention will be described with reference to FIGS. 32A and 32B.

[0474] 32A includes a power storage device 2612 including a power storage device of one embodiment of the present invention, and a solar panel 2610. The power storage device 2612 is electrically connected to the solar panel 2610 through a wiring 2611 or the like. The power storage device 2612 may be electrically connected to a ground-mounted charging device 2604. The power obtained by the solar panel 2610 can be charged to the power storage device 2612. The power stored in the power storage device 2612 can be charged to the power storage device 2602 included in the vehicle 2603 via the charging device 2604. The power storage device 2612 is preferably installed in an underfloor space. By installing the power storage device 2612 in the underfloor space, the space above the floor can be effectively utilized. Alternatively, the power storage device 2612 may be installed on the floor.

[0475] The power stored in the power storage device 2612 can also be supplied to other electronic devices in the house. Therefore, even when power cannot be supplied from a commercial power source due to a power outage or the like, the power storage device 2612 of one embodiment of the present invention can be used as an uninterruptible power supply, enabling the use of electronic devices.

[0476] 32B illustrates an example of a power storage device 700 according to one embodiment of the present invention. As illustrated in FIG. 32B, a power storage device 791 according to one embodiment of the present invention is installed in an underfloor space 796 of a building 799.

[0477] A control device 790 is installed in the power storage device 791, and the control device 790 is electrically connected to a distribution board 703, a power storage controller 705 (also called a control device), a display 706, and a router 709 by wiring.

[0478] Electric power is sent from commercial power source 701 to distribution board 703 via service line attachment section 710. Electric power is also sent to distribution board 703 from power storage device 791 and commercial power source 701, and distribution board 703 supplies the sent electric power to general load 707 and power storage load 708 via an outlet (not shown).

[0479] The general load 707 is, for example, an electrical appliance such as a television or a personal computer, and the power storage load 708 is, for example, an electrical appliance such as a microwave oven, a refrigerator, or an air conditioner.

[0480] The power storage controller 705 has a measurement unit 711, a prediction unit 712, and a planning unit 713. The measurement unit 711 has a function of measuring the amount of power consumed by the general load 707 and the power storage load 708 during one day (for example, from midnight to midnight). The measurement unit 711 may also have a function of measuring the amount of power of the power storage device 791 and the amount of power supplied from the commercial power source 701. The prediction unit 712 has a function of predicting the amount of power demand to be consumed by the general load 707 and the power storage load 708 during the next day, based on the amount of power consumed by the general load 707 and the power storage load 708 during the previous day. The planning unit 713 has a function of creating a plan for charging and discharging the power storage device 791, based on the amount of power demand predicted by the prediction unit 712.

[0481] The amount of power consumed by the general load 707 and the power storage load 708 measured by the measurement unit 711 can be confirmed on the display 706. It can also be confirmed on an electrical device such as a television or a personal computer via the router 709. It can also be confirmed on a mobile electronic device such as a smartphone or a tablet via the router 709. The amount of power demand for each time period (or each hour) predicted by the prediction unit 712 can also be confirmed on the display 706, the electrical device, or the mobile electronic device.

[0482] This embodiment mode can be implemented in appropriate combination with other embodiment modes.

[0483] (Notes regarding the present specification) The above-described embodiments and the respective components in the embodiments will be described below with additional notes.

[0484] The configurations shown in each embodiment can be combined with the configurations shown in other embodiments as appropriate to form one aspect of the present invention. Furthermore, when multiple configuration examples are shown in one embodiment, the configuration examples can be combined as appropriate.

[0485] In addition, the content (or even a part of the content) described in one embodiment can be applied to, combined with, or replaced with another content (or even a part of the content) described in that embodiment, and / or with the content (or even a part of the content) described in one or more other embodiments.

[0486] The contents described in the embodiments refer to the contents described in each embodiment using various figures or the contents described using text in the specification.

[0487] Furthermore, a figure (or even a part thereof) described in one embodiment can be combined with another part of that figure, another figure (or even a part thereof) described in that embodiment, and / or a figure (or even a part thereof) described in one or more other embodiments to form even more figures.

[0488] In addition, in the present specification and the like, in the block diagrams, components are classified by function and shown as independent blocks. However, in actual circuits, etc., it is difficult to separate components by function, and there may be cases where one circuit is involved in multiple functions, or one function is involved across multiple circuits. Therefore, the blocks in the block diagrams are not limited to the components described in the specification, but may be rephrased appropriately depending on the situation.

[0489] In addition, in the drawings, the size, layer thickness, or region is shown at an arbitrary size for convenience of explanation. Therefore, it is not necessarily limited to the 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, it is possible to include variations in signal, voltage, or current due to noise, or variations in signal, voltage, or current due to timing deviations.

[0490] In this specification and the like, when describing the connection relationship of a transistor, the term "one of the source or drain" (or first electrode or first terminal) is used, and the other of the source and drain is referred to as "the other of the source or drain" (or second electrode or second terminal). This is because the source and drain of a transistor vary depending on the structure or operating conditions of the transistor. Note that the names of the source and drain of a transistor can be appropriately changed to source (drain) terminal, source (drain) electrode, etc. depending on the situation.

[0491] Furthermore, in this specification and the like, terms such as "electrode" and "wiring" do not limit the functionality of these components. For example, an "electrode" may be used as part of a "wiring," and vice versa. Furthermore, terms such as "electrode" and "wiring" also include cases where multiple "electrodes," "wirings," etc. are integrally formed.

[0492] Furthermore, in this specification and the like, voltage and potential can be interchanged as appropriate. Voltage refers to the potential difference from a reference potential. For example, if the reference potential is a ground voltage (earth voltage), voltage can be interchanged with potential. Ground potential does not necessarily mean 0 V. Note that potential is relative, and the potential applied to wiring, etc. may change depending on the reference potential.

[0493] In this specification and the like, terms such as "film" and "layer" can be interchangeable depending on the circumstances. For example, the term "conductive layer" can be changed to the term "conductive film." Or, for example, the term "insulating film" can be changed to the term "insulating layer."

[0494] In this specification, a switch refers to a device that has the function of controlling whether a current flows by being in a conductive state (on state) or a non-conductive state (off state), or a device that has the function of selecting and switching a path for a current to flow.

[0495] In this specification, the channel length refers to, for example, in a top view of a transistor, a region where a semiconductor (or a portion in the semiconductor through which current flows when the transistor is on) and a gate overlap, or a distance between a source and a drain in a region where a channel is formed.

[0496] In this specification, the channel width refers to, for example, the length of the region where the semiconductor (or the portion in the semiconductor through which current flows when the transistor is on) and the gate electrode overlap, or the length of the portion where the source and drain face each other in the region where the channel is formed.

[0497] In this specification, "A and B are connected" includes not only a direct connection between A and B, but also an electrical connection between A and B. Here, "A and B are electrically connected" means that when an object having some kind of electrical effect exists between A and B, transmission of an electrical signal between A and B is possible. [Explanation of symbols]

[0498] BG1 to BG3: back gate potential, C1 to C3: capacitors, FC1 to FC3: capacitors, FM1 to FM4: transistors, M1: transistor, M2: transistor, M3: transistor, M4: transistor, S: selection signal, 100: semiconductor device, 110: secondary battery, 120: control circuit, 130: load, 140: charger, 150: power transistor

Claims

[Claim 1] a first transistor; a first voltage generating circuit that generates a first voltage; a second voltage generating circuit that generates a second voltage; the first voltage generating circuit includes a second transistor and a first capacitor; the second voltage generating circuit includes a third transistor and a second capacitor; A control circuit for a secondary battery, wherein a difference between the first voltage and the second voltage is set according to a threshold voltage of the first transistor.

Images