JP7109973B2 - semiconductor equipment - Google Patents

Description

One embodiment of the present invention relates to a semiconductor device.

One embodiment of the present invention also relates to a semiconductor device. Note that one aspect of the present invention is not limited to the above technical field. The technical field of the invention disclosed in this specification and the like relates to products, methods, or manufacturing methods. Alternatively, one aspect of the invention relates to a process, machine, manufacture, or composition of matter.

Note that a semiconductor device in this specification and the like refers to all devices that can function by utilizing semiconductor characteristics. Display devices, light-emitting devices, storage devices, electro-optical devices, power storage devices, control systems, semiconductor circuits, and electronic devices may include semiconductor devices.

2. Description of the Related Art In recent years, many devices such as sensors and actuators have been installed in vehicles as the performance of vehicles has improved. These devices are electrically controlled by semiconductor devices for processing signals (see, for example, US Pat.

JP 2016-159766 A

2. Description of the Related Art A semiconductor device including a circuit for signal processing is composed of elements such as transistors. A semiconductor device mounted on a vehicle or the like is affected by heat from, for example, a high-temperature engine. In a transistor whose channel formation region is made of silicon (Si transistor), electrical characteristics change when the transistor performing signal processing is exposed to high temperatures. Variation in electrical characteristics is a problem when it occurs in memory devices that hold, write, and read data.

As a transistor whose electrical characteristics change little due to the influence of heat, there is a transistor (OS transistor) whose channel formation region is formed using a metal oxide (also referred to as an oxide semiconductor). A semiconductor device including an OS transistor can maintain switching characteristics even at a high temperature of 200.degree.

However, at high temperatures, the current flowing in the OS transistor (on-current) does not easily change, but the leak current (off-current) flowing in the off-state gradually increases. Therefore, in order to maintain good switching characteristics at high temperatures, high voltage driving (increasing amplitude voltage) is desirable. On the other hand, if a high voltage is applied to the OS transistor at high temperature, another problem arises such that deterioration of the OS transistor is accelerated. Further, in the case where the OS transistor is controlled by low-voltage driving (reduced amplitude voltage) in order to suppress deterioration of the OS transistor at high temperatures, there arises a problem that a sufficient on-current cannot be obtained.

In view of the above problems, an object of one embodiment of the present invention is to provide a highly reliable semiconductor device. Another object of one embodiment of the present invention is to provide a semiconductor device with excellent low power consumption.

The description of these problems does not preclude the existence of other problems. Note that one embodiment of the present invention does not necessarily solve all of these problems. Problems other than these are self-evident from the descriptions of the specification, drawings, claims, etc., and it is possible to extract problems other than these from the descriptions of the specification, drawings, claims, etc. is.

One aspect of the present invention includes a sensor, a system control circuit, a power supply control circuit, and a storage device, wherein the sensor has a function of outputting an acquired first signal to the system control circuit; The control circuit has a function of outputting a second signal for switching between a plurality of voltage levels output by the power control circuit according to the first signal, and the power control circuit outputs A semiconductor device has a function of outputting one of voltage levels to a memory device, and the memory device is a semiconductor device including a transistor having a metal oxide in a channel formation region.

One aspect of the present invention includes a sensor, a system control circuit, a power supply control circuit, a storage device, and a processor, and the sensor has a function of outputting an acquired first signal to the system control circuit. and the system control circuit generates a second signal for switching between the plurality of voltage levels output by the power supply control circuit and a third signal for switching the processor between the active state and the hibernation state in response to the first signal. , the power control circuit has a function of outputting one of the voltage levels to the memory device according to the second signal or the third signal, and the memory device has a function of A semiconductor device including a transistor including a metal oxide.

In one embodiment of the present invention, the transistor preferably has a gate electrode to which a potential lower than the potential applied to the source of the transistor and the potential applied to the drain of the transistor is included.

In one embodiment of the present invention, the metal oxide is preferably a semiconductor device containing one or both of In (indium) and Zn (zinc).

In one embodiment of the present invention, the semiconductor device preferably contains Ga (gallium) as the metal oxide.

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

One embodiment of the present invention can provide a highly reliable semiconductor device. Alternatively, one embodiment of the present invention can provide a semiconductor device with excellent low power consumption.

Note that the description of these effects does not preclude the existence of other effects. Note that one embodiment of the present invention does not need to have all of these effects. Effects other than these are self-evident from the descriptions of the specification, drawings, claims, etc., and it is possible to extract effects other than these from the descriptions of the specification, drawings, claims, etc. is.

FIG. 3 is a block diagram illustrating a configuration example of a semiconductor device; 6A and 6B are graphs illustrating electrical characteristics of an OS transistor; 1A and 1B are schematic diagrams illustrating electrical characteristics of an OS transistor; 4A and 4B are circuit diagrams each illustrating a configuration example of a semiconductor device; 4A and 4B are circuit diagrams each illustrating a configuration example of a semiconductor device; 4A and 4B are circuit diagrams each illustrating a configuration example of a semiconductor device; FIG. 4 is a waveform diagram for explaining a configuration example of a semiconductor device; 4A and 4B are block diagrams and waveform diagrams each illustrating a configuration example of a semiconductor device; FIG. 3 is a block diagram illustrating a configuration example of a semiconductor device; 1 is a perspective view illustrating a configuration example of a semiconductor device; FIG. 4A and 4B are cross-sectional views each showing a structural example of a transistor; 1A and 1B are a top view and a cross-sectional view illustrating a structural example of a transistor; 1A and 1B are a top view and a cross-sectional view illustrating a structural example of a transistor; 1A and 1B are a top view and a cross-sectional view illustrating a structural example of a transistor; 1A and 1B are a top view and a cross-sectional view illustrating a structural example of a transistor; 1A and 1B are a top view and a cross-sectional view illustrating a structural example of a transistor; 1A and 1B are diagrams each showing a configuration example of an electronic device; FIG.

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

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

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

Moreover, in this specification and the like, a metal oxide is a metal oxide in a broad expression. Metal oxides are classified into oxide insulators, oxide conductors (including transparent oxide conductors), oxide semiconductors (also referred to as oxide semiconductors), and the like.

For example, when a metal oxide is used for a channel formation region of a transistor, the metal oxide is sometimes called an oxide semiconductor. That is, when a metal oxide has at least one of amplifying action, rectifying action, and switching action, the metal oxide can be called a metal oxide semiconductor. That is, a transistor including a metal oxide in a channel formation region can be called an "oxide semiconductor transistor" or an "OS transistor." Similarly, the above-described “transistor using an oxide semiconductor” is also a transistor including a metal oxide in a channel formation region.

(Embodiment 1)
A structure of a semiconductor device which is one embodiment of the present invention is described.

FIG. 1 is a block diagram of a semiconductor device. The semiconductor device 100 has a sensor 101 , a system control circuit 102 (also referred to simply as a control circuit), a power supply control circuit 103 , a storage device 104 and an arithmetic device 105 .

The sensor 101 has the function of a sensor (temperature sensor) capable of measuring the environmental temperature. The sensor 101 has a function of outputting a data signal Dt corresponding to temperature to the system control circuit 102 under the control of the system control circuit 102 . The data signal Dt is also called a first signal or temperature data.

Note that the sensor 101 has a function of sensing the temperature around the semiconductor device 100 and outputting a data signal Dt corresponding to the temperature. As the sensor 101, for example, a resistance temperature detector made of platinum, nickel, copper, or the like, a thermistor, a thermocouple, an IC temperature sensor, or the like can be used.

The system control circuit 102 has a function of periodically acquiring the data signal Dt. The system control circuit 102 has a function of outputting a data signal Dc1 for switching a plurality of voltage levels output by the power supply control circuit 103 according to the data signal Dt. For example, when the data signal Dt determines that the environmental temperature is high, a plurality of voltage levels output by the power supply control circuit 103 are switched according to the state of the storage device 104 . The system control circuit 102 also calls the data signal Dt a second signal or a switching signal.

A high ambient temperature means 83° C. or higher, 121° C. or higher, 144° C. or higher, or 192° C. or higher.

The system control circuit 102 also has a function of outputting a data signal Dc1 for switching the arithmetic device 105 between an active state and a dormant state. Note that a data signal for switching the arithmetic device 105 between an active state and a resting state (also referred to as power gating) may be a signal different from the data signal Dc1.

The power control circuit 103 has a function of switching between a plurality of power supply voltages to be applied to the storage device 104 . As the plurality of power supply voltages, two types of voltage levels, a voltage for holding data in the storage device 104 and a voltage for high-speed data access, will be exemplified and explained. Switching between two voltage levels in the power supply control circuit 103 is particularly effective for improving reliability and reducing power consumption when the environmental temperature is high. In one embodiment of the present invention, another voltage may be set.

When the ambient temperature is high, even if the memory device 104 is formed of an OS transistor, leakage current (off-state current) that flows when the device is turned off gradually increases. Therefore, high voltage driving is desirable in order to maintain good switching characteristics as described above. On the other hand, if a high voltage is continuously applied to a transistor in a high-temperature environment, the electrical characteristics of the transistor, such as the threshold voltage, deteriorate at an accelerated rate. Therefore, in the configuration of this embodiment, the power supply control circuit 103 switches the power supply voltage to be applied to the storage device 104 so that high-voltage driving is performed during data access and low-voltage driving is performed during data retention in a high-temperature environment.

With the above structure, acceleration of deterioration of the OS transistor when a high voltage is applied to the OS transistor in a high-temperature environment can be suppressed. In addition, even if a sufficient on-current cannot be obtained when controlling the OS transistor by low-voltage driving in a high-temperature environment, the configuration switches to high-voltage driving during data access, so data is not affected. Writing and reading can be performed at high speed.

A voltage for data access is a voltage given by voltage VDDH and ground voltage GND (0 V). The voltage for data retention is assumed to be the voltage given by the voltage VDDL and the ground voltage GND. The voltage VDDH is assumed to be higher than the voltage VDDL. The voltage VDDL is assumed to be higher than the ground voltage GND. By adopting a configuration in which the voltage level is switched according to the environmental temperature, power consumption increases due to an increase in off-state current in a high-temperature environment, and switching characteristics of the storage device 104 in a high-temperature environment decrease. It is possible to suppress the decrease in reliability associated with

The storage device 104 has a function of holding data input/output to/from the arithmetic device 105 . The memory device 104 includes a transistor including a metal oxide in a channel formation region (hereinafter referred to as an OS transistor). The OS transistor is described as an n-channel transistor.

The memory device 104 whose circuit is formed using OS transistors can maintain the switching characteristics of the transistors even in a high-temperature environment. Therefore, a highly reliable semiconductor device can be obtained. In addition, since switching characteristics can be maintained even in a high-temperature environment as compared with a Si transistor or the like, a separate cooling means or the like is not required, and the size and power consumption of the semiconductor device can be reduced. In addition, the layout area can be reduced by stacking the OS transistors. Note that details of the OS transistor will be described in Embodiment 2 or the like which will be described later.

The memory device 104 whose circuit is composed of OS transistors is preferably a memory device having a static RAM (SRAM) circuit configuration. Compared to a dynamic RAM type (DRAM type) or the like, an SRAM type circuit can write and read data at high speed, and can exchange data favorably with the arithmetic unit 105 . .

The arithmetic device 105 has a function of performing arithmetic processing using data input/output to/from the storage device 104 . Like the memory device 104, the arithmetic device 105 is composed of an OS transistor. The OS transistor is described as an n-channel transistor. Arithmetic device 105 may also be referred to as a processor.

The arithmetic unit 105 reads and writes data necessary for arithmetic processing of data from/to the storage device. Therefore, it is preferable that switching between the two types of voltage levels in the power supply control circuit 103 described above is performed according to whether or not the arithmetic unit 105 is to be operated.

In the semiconductor device 100 having the configuration of this embodiment, the magnitude of the power supply voltage applied to the storage device 104 is changed according to the data signal output from the system control circuit 102 in accordance with the data signal related to the environmental temperature acquired by the sensor 101. can be As the plurality of power supply voltages, a voltage level for holding data in the memory device 104 and a voltage level for high-speed data access are used. In a high-temperature environment, the power supply control circuit 103 switches the power supply voltage to be applied to the storage device 104 so that high-voltage driving is performed during data access and low-voltage driving is performed during data retention.

With the above structure, acceleration of deterioration of the OS transistor when a high voltage is applied to the OS transistor in a high-temperature environment can be suppressed. In addition, even if a sufficient on-current cannot be obtained when controlling the OS transistor by low-voltage driving in a high-temperature environment, the configuration switches to high-voltage driving during data access, so data is not affected. Writing and reading can be performed at high speed.

By adopting the configuration of the present embodiment, when controlling a power device or the like in a vehicle where the environmental temperature changes significantly, even if the semiconductor device for controlling is arranged near the device with a large temperature change, the power consumption is reduced. In addition to suppressing an increase in , a semiconductor device capable of maintaining good switching characteristics can be provided. In addition, since deterioration of transistor characteristics in a high-temperature environment can be suppressed, a highly reliable semiconductor device can be obtained.

FIG. 2 is a graph showing the current (Ids) flowing between the source and the drain with respect to the gate-source voltage (Vgs) of the OS transistor and the field effect mobility, which are applicable to each circuit constituting the semiconductor device 100. .

The graph shown in FIG. 2 illustrates variations in electrical properties at temperatures of 27° C., 83° C., 121° C., 144° C., and 192° C. FIG. As shown in FIG. 2, when the temperature is 27° C., the current (Ids) flowing between the source and the drain when the voltage between the gate and the source (Vgs) is 0 V is small enough to be below the lower limit of measurement.

On the other hand, as shown in FIG. 2, the change in current Ids with respect to the change in voltage Vgs is small when Vgs is large, but increases as Vgs approaches 0 V and as the temperature rises. That is, the current flowing when Vgs is 0V increases as the temperature rises. Although the OS transistor can maintain its switching characteristics even at 200° C. or higher, it is difficult for the Si transistor to maintain its switching characteristics because its characteristics fluctuate more at high temperatures.

FIG. 3A is a graph schematically showing changes in electrical characteristics with respect to temperature changes described in FIG. As described above, the OS transistor has an increased current flow when Vgs is 0 V in a high temperature environment. Due to the variation in the electrical characteristics of the transistor, good switching characteristics cannot be maintained, and the reliability of the semiconductor device is lowered. On the other hand, controlling a transistor with a high power supply voltage in a high-temperature environment accelerates the deterioration of the electrical characteristics of the transistor and significantly degrades the performance of the semiconductor device.

The power supply voltage applied to the memory device 104 is the voltage schematically shown in FIG. That is, in a high-temperature environment, the power supply voltage is set so as to fall within the range 106 in FIG. The range 107 in (B) is set. That is, the voltage for data retention is the voltage given by the voltage VDDL and the ground voltage GND, and the voltage for data access is the voltage given by the voltage VDDH and the ground voltage GND.

Next, the operation in the storage device 104 accompanying the operation of the power supply control circuit 103 described above will be described. FIG. 4A is a circuit diagram of a memory element in the memory device 104. FIG. FIG. 4A shows an SRAM memory element. FIG. 4A shows a circuit diagram in which an inverter loop is formed by a bit line BL, a switch 111 connected to an inverted bit line BLB, and an inverter circuit 112 for holding data.

FIG. 4B is a circuit diagram in which the switch 111 illustrated in FIG. 4A is replaced with transistors 113 and 114. FIG. The transistors 113 and 114 are n-channel transistors. The transistors 113 and 114 are controlled to be on or off by a word signal applied to the word line WL.

FIG. 4C is a circuit diagram in which the inverter circuit 112 illustrated in FIG. 4A is replaced with transistors 113 to 116. FIG. FIG. 4C is a circuit formed of n-channel transistors, and is a pseudo inverter circuit that outputs a signal obtained by inverting the signal of the input terminal IN to the output terminal OUT.

FIG. 5A shows a specific circuit configuration of the power supply control circuit 103. As shown in FIG. A power supply control circuit 103 illustrated in FIG. 5A includes transistors 121 and 122 and an inverter circuit 123 . Data signal Dc1 is input to the gate of transistor 121 and the input terminal of inverter circuit 123 . A signal obtained by inverting the logic of the data signal Dc1 output from the output terminal of the inverter circuit 123 is input to the gate of the transistor 122 . A voltage VDDH is applied to one of the source and drain of the transistor 121 . A voltage VDDL is applied to one of the source and drain of the transistor 122 . The other of the source or the drain of the transistor 121 and the other of the source or the drain of the transistor 122 are connected to the memory device 104 . With this structure, the power supply voltage of the memory device 104 can be switched according to the data signal Dc1.

The power supply voltage switched by the power supply control circuit 103 is applied as the power supply voltage of the inverter circuit 123 included in the memory device 104 . For example, as shown in FIG. 5B, in a high-temperature environment, a power supply voltage VDDH is applied so that high-voltage driving is performed during data access. Further, as shown in FIG. 5C, in a high-temperature environment, a power supply voltage VDDL is applied so that low-voltage driving is performed during data retention. During data retention, the power supply voltage VDDL can be lowered to such an extent that the input/output logic of the inverter circuit 112 does not cause an erroneous logic change due to factors such as noise.

By switching the configurations of FIGS. 5B and 5C between when data is accessed and when data is held, the amplitude voltage of the signal input to and output from the inverter circuit 112 can be switched.

Let _{SL_ACC} be a low-level signal applied to the input terminal of the inverter circuit 112 during data access. In a high-temperature environment, Vgs applied to the transistor 115 increases, The flowing current _{IH increases, and a high level signal SH_ACC is} output from the output terminal OUT. Assuming that the signal applied to the input terminal of inverter circuit 112 at the time of data access is _{SH_ACC} , in a high temperature environment, Vgs applied to transistor 116 increases as shown in FIG. _H increases and _{SL_ACC} is output from the output terminal OUT.

Similarly, when the low-level signal applied to the input terminal of the inverter circuit 112 during data retention is S _{L_STB} , in a high-temperature environment, Vgs is applied to the transistor 115 as shown in FIG. becomes smaller than in the state of FIG. 6A, and the flowing current _{IL decreases, but a high level signal SH_STB is} output from the output terminal OUT. A high-level signal supplied to the input terminal of the inverter circuit 112 during data retention is _{SH_STB} . In a high-temperature environment, Vgs applied to the transistor 116 increases as shown in FIG. Although the flowing current _{IL is smaller than the state of FIG. 6B, SL_STB is} output from the output terminal OUT.

FIG. 7 is a waveform diagram showing the magnitude relationship of the potentials of the signal _{SL_ACC} , signal _{SH_ACC} , signal _{SL_STB} , and signal _{SH_STB} described with reference to FIG. As illustrated in FIG. 7, signal _{SL_ACC} and signal _{SH_ACC} correspond to signals having amplitude voltages in range 106 in FIG. 3B. Signal _{SL_STB} and signal _{SH_STB} correspond to signals having amplitude voltages in range 107 in FIG. 3B. The power supply control circuit 103 switches the power supply voltage to be applied to the storage device 104 so that high voltage driving is performed during data access and low voltage driving is performed during data retention.

With the above structure, acceleration of deterioration of the OS transistor when a high voltage is applied to the OS transistor in a high-temperature environment can be suppressed. In addition, even if a sufficient on-current cannot be obtained when controlling the OS transistor by low-voltage driving in a high-temperature environment, the configuration switches to high-voltage driving during data access, so data is not affected. Writing and reading can be performed at high speed.

Note that although the change in electrical characteristics can be suppressed by switching the power supply voltage as described above, it is difficult to suppress an increase in off current in a high-temperature environment. In other words, the higher the temperature of the OS transistor, the more the threshold voltage shifts negatively and the subthreshold coefficient increases. As a result, the current flowing between the source and the drain when the voltage of the gate with respect to the source is 0 V (also called cutoff current) increases.

Therefore, by setting the potential applied to the gate when the transistor is non-conducting (off state) to be lower than the potential applied to the source or drain of the transistor, the potential between the source and the drain can be reduced even in a high-temperature operating environment. to a low state. Specifically, in the power supply control circuit 103, in addition to the two types of voltages VDDH and VDDL, the potential applied to the gate when the transistor is non-conducting (off state) is set to the ground potential (VSS) or lower than VSS. , the low power supply potential VLL keeps the current flowing between the source and the drain low even in a high-temperature operating environment.

That is, when the potential applied to the gate when the OS transistor is off (off state) is lower than the potential applied to the source or drain, the off current of the OS transistor is very low even in a high-temperature operating environment. It is possible to use the property that

For example, as shown in FIG. 8A, in the power supply control circuit 103, in addition to the ground potential GND (VSS), a low power supply potential VLL lower than VSS is prepared, and the voltage applied to the memory device 104 is finely switched. is preferred.

With the structure in FIG. 8A, a plurality of voltage levels different from those in FIG. 7 can be switched according to data access or data retention. For example, FIG. 8B is a waveform diagram showing the magnitude relationship of the potentials of the signal S _{L_ACC , the signal S H_ACC ,} the signal S _{L_STB} , and the signal S _{H_STB} as in FIG. The low level signals of _{L_STB} and signal _{SH_STB} are switched to a low potential VLL which is lower than the ground potential (VSS).

With the above structure, it is possible to utilize the property that the off-state current of the OS transistor is very small even in a high-temperature operating environment.

FIG. 9A is a block diagram for explaining a configuration different from that of FIG. The system control configuration by the system control circuit 102 may be a configuration in which a power gating signal Dc2 different from the control signal Dc1 of the power supply control circuit 103 is combined with the power gating operation of the arithmetic device 105 . For example, it is effective to apply the same power supply voltage to the storage device 104 during power gating as during data retention, and to apply the same power supply voltage to the storage device 104 during non-power gating as during data access.

FIG. 9B is a block diagram for explaining a configuration different from that in FIG. The arithmetic device 105 may have a separate configuration from the block where the sensor 101 and the storage device 104 are gathered.

FIG. 10 shows an example in which the above semiconductor device is incorporated into an IC for a control system.

FIG. 10A shows an example of an IC incorporating a semiconductor device. An IC 7000A shown in FIG. 10A has leads 7001 and a circuit portion 7003A. The IC 7000A is mounted on a printed circuit board 7002, for example. A plurality of such IC chips are combined and electrically connected to each other on the printed board 7002 to complete a board (mounting board 7004) on which electronic components are mounted. In the circuit portion 7003A, the various circuits described in the above embodiments are divided into one die or a plurality of dies and provided. The circuit portion 7003 A is roughly divided into an OS transistor layer 7031 and a wiring layer 7032 .

Note that the OS transistor layer may be a single layer, or may be stacked with a wiring layer interposed therebetween. Specifically, FIG. 10B shows another example of an IC incorporating a semiconductor device. An IC 7000B shown in FIG. 10B has leads 7001 and a circuit portion 7003B. The IC 7000B is mounted on a printed circuit board 7002, for example. A plurality of such IC chips are combined and electrically connected to each other on the printed board 7002 to complete a board (mounting board 7004) on which electronic components are mounted. In the circuit portion 7003B, the various circuits described in the above embodiments are provided on one die or divided into a plurality of dies. The circuit portion 7003 A is roughly divided into an OS transistor layer 7031 , a wiring layer 7032 and an OS transistor layer 7033 . The OS transistor layer 7031 is connected to the OS transistor layer 7033 through the wiring layer 7032 . Another OS transistor layer can be arranged over the OS transistor layer 7033 with another wiring layer interposed therebetween. Since a plurality of OS transistor layers can be stacked, the size of the circuit portion 7003B can be easily reduced.

In FIGS. 10A and 10B, a QFP (Quad Flat Package) is applied to the packages of the ICs 7000A and 7000B, but the form of the package is not limited to this.

As described above, in the semiconductor device 100 having the configuration of this embodiment, the data signal output by the system control circuit 102 is switched according to the environmental temperature acquired by the sensor 101, and the magnitude of the power supply voltage applied to the storage device 104 is changed. can be configured to be different. As the plurality of power supply voltages, a voltage level for holding data in the memory device 104 and a voltage level for high-speed data access are used. In a high-temperature environment, the power supply control circuit 103 switches the power supply voltage to be applied to the storage device 104 so that high-voltage driving is performed during data access and low-voltage driving is performed during data retention.

With the above structure, acceleration of deterioration of the OS transistor when a high voltage is applied to the OS transistor in a high-temperature environment can be suppressed. In addition, even if a sufficient on-current cannot be obtained when controlling the OS transistor by low-voltage driving in a high-temperature environment, the configuration switches to high-voltage driving during data access, so data is not affected. Writing and reading can be performed at high speed.

By adopting the configuration of the present embodiment, when controlling a power device or the like in a vehicle where the environmental temperature changes significantly, even if the semiconductor device for controlling is arranged near the device with a large temperature change, the power consumption is reduced. In addition to suppressing an increase in , a semiconductor device capable of maintaining good switching characteristics can be provided. In addition, since deterioration of transistor characteristics in a high-temperature environment can be suppressed, a highly reliable semiconductor device can be obtained.

The structures, methods, and the like described in this embodiment can be combined as appropriate with the structures, methods, and the like described in other embodiments.

(Embodiment 2)
In this embodiment, a structural example of an OS transistor that can be applied to the semiconductor devices described in the above embodiments will be described.

<Example of transistor structure>
11A to 11C are cross-sectional views of a transistor 500, which is an OS transistor, illustrated as an example. 11A is a cross-sectional view of the transistor 500 in the channel length direction, FIG. 11B is a cross-sectional view of the transistor 500 in the channel width direction, and FIG. 11C is a cross-sectional view of the transistor 300 in the channel width direction. It is a diagram.

The transistor 500 is a transistor (OS transistor) including a metal oxide in a channel formation region. Since the transistor 500 can have favorable switching characteristics even in a high temperature environment of 200° C., the semiconductor device can be highly reliable even in a high temperature environment. In addition, since off-state current can be reduced, a semiconductor device with low power consumption can be obtained even in a high-temperature environment.

In the cross-sectional views of FIGS. 11A to 11C, an insulator 512, an insulator 514, and an insulator 516 are stacked in this order. Any of the insulator 512, the insulator 514, and the insulator 516 preferably uses a substance having barrier properties against oxygen and hydrogen.

For the insulator 514, for example, it is preferable to use a film having a barrier property such that hydrogen or impurities do not diffuse from the underlying substrate or the like into the region where the transistor 500 is provided.

As an example of a film having a barrier property against hydrogen, silicon nitride formed by a CVD method can be used. As a film having a barrier property against hydrogen, for example, the insulator 514 is preferably formed using a metal oxide such as aluminum oxide, hafnium oxide, or tantalum oxide.

In particular, aluminum oxide has a high shielding effect of preventing the penetration of both oxygen and impurities such as hydrogen and moisture, which cause variations in the electrical characteristics of the transistor. Therefore, aluminum oxide can prevent impurities such as hydrogen and moisture from entering the transistor 500 during and after the manufacturing process of the transistor. In addition, release of oxygen from the oxide forming the transistor 500 can be suppressed. Therefore, it is suitable for use as a protective film for the transistor 500 .

Further, for example, by using a material with a relatively low dielectric constant as an interlayer film for the insulators 512 and 516, parasitic capacitance generated between wirings can be reduced. For example, the insulators 512 and 516 can be formed using a silicon oxide film, a silicon oxynitride film, or the like.

A transistor 500 is provided above the insulator 516 .

11A and 11B, the transistor 500 includes an insulator 520 over an insulator 516, an insulator 522 over an insulator 520, and an insulator 522. Insulator 524 overlying, oxide 530a overlying insulator 524, oxide 530b overlying oxide 530a, and oxide 530b overlying oxide 530b spaced apart from each other. A conductor 542a and a conductor 542b, an insulator 580 which is provided over the conductor 542a and the conductor 542b and has an opening formed between the conductor 542a and the conductor 542b, and which is provided in the opening The insulator 550, the oxide 530b, the conductor 542a, the conductor 542a, the conductor 542b, the insulator 580, and the conductor 560 are arranged between the conductor 560, the oxide 530b, the conductor 542a, and the conductor 542b. and oxide 530 c disposed between insulator 580 and insulator 550 .

11A and 11B, an insulator 544 is preferably provided between oxides 530a, 530b, conductors 542a and 542b, and an insulator 580. . 11A and 11B, the conductor 560 includes a conductor 560a provided inside the insulator 550 and a conductor 560a embedded inside the conductor 560a. 560b and . Further, an insulator 574 is preferably provided over the insulator 580, the conductor 560, and the insulator 550 as shown in FIGS.

Note that the oxide 530a, the oxide 530b, and the oxide 530c may be collectively referred to as the oxide 530 below. Further, the conductor 542a and the conductor 542b may be collectively referred to as a conductor 542 in some cases.

Note that although the transistor 500 has a structure in which three layers of the oxide 530a, the oxide 530b, and the oxide 530c are stacked in a region where a channel is formed and in the vicinity thereof, the present invention is limited to this. not a thing For example, a single layer of the oxide 530b, a two-layer structure of the oxides 530b and 530a, a two-layer structure of the oxides 530b and 530c, or a stacked structure of four or more layers may be employed. Although the conductor 560 has a two-layer structure in the transistor 500, the present invention is not limited to this. For example, the conductor 560 may have a single-layer structure or a laminated structure of three or more layers. Further, the transistor 500 illustrated in FIGS. 11A and 11B is an example, and the structure thereof is not limited, and an appropriate transistor may be used depending on the circuit structure and driving method.

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

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

The insulator 550 functions as a gate insulating film.

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

Specifically, an oxide material from which part of oxygen is released by heating is preferably used as the insulator having the excess oxygen region. The oxide that desorbs oxygen by heating means that the desorption amount of oxygen in terms of oxygen atoms is 1.0×10 ¹⁸ atoms/cm ³ or more, preferably 1, in TDS (Thermal Desorption Spectroscopy) analysis. It is an oxide film having a concentration of 0.0×10 ¹⁹ atoms/cm ³ or more, more preferably 2.0×10 ¹⁹ atoms/cm ³ or 3.0×10 ²⁰ atoms/cm ³ or more. The surface temperature of the film during the TDS analysis is preferably in the range of 100° C. or higher and 700° C. or lower, or 100° C. or higher and 400° C. or lower.

In addition, when the insulator 524 has an excess oxygen region, the insulator 522 preferably has a function of suppressing diffusion of oxygen (eg, oxygen atoms, oxygen molecules, etc.) (the above oxygen is difficult to permeate).

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

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

In particular, an insulator containing an oxide of one or both of aluminum and hafnium, which is an insulating material having a function of suppressing diffusion of impurities and oxygen (through which oxygen hardly penetrates), is preferably used. As the insulator containing oxide of one or both of aluminum and hafnium, aluminum oxide, hafnium oxide, oxide containing aluminum and hafnium (hafnium aluminate), or the like is preferably used. When the insulator 522 is formed using such a material, the insulator 522 suppresses release of oxygen from the oxide 530 and entry of impurities such as hydrogen from the periphery of the transistor 500 into the oxide 530. act as a layer.

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

Insulator 520 is also preferably thermally stable. For example, since silicon oxide and silicon oxynitride are thermally stable, an insulator made of a high-k material and the insulator 520 are combined to form a thermally stable laminated structure with a high relative dielectric constant. can be done.

Note that the insulator 520, the insulator 522, and the insulator 524 may have a stacked structure of two or more layers. In that case, it is not limited to a laminated structure made of the same material, and a laminated structure made of different materials may be used.

In the transistor 500, a metal oxide functioning as an oxide semiconductor is preferably used for the oxide 530 including a channel formation region. For example, as the oxide 530, In-M-Zn oxide (element M is aluminum, gallium, yttrium, copper, vanadium, beryllium, boron, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium , hafnium, tantalum, tungsten, magnesium, or the like) may be used. Alternatively, as the oxide 530, an In--Ga oxide or an In--Zn oxide may be used.

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

Since the oxide 530 includes the oxide 530a under the oxide 530b, diffusion of impurities from a structure formed below the oxide 530a to the oxide 530b can be suppressed. In addition, by providing the oxide 530c over the oxide 530b, diffusion of impurities from a structure formed above the oxide 530c to the oxide 530b can be suppressed.

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

In addition, it is preferable that the energies of the conduction band bottoms of the oxides 530a and 530c be higher than the energies of the conduction band bottoms of the oxide 530b. Also, in other words, the electron affinities of the oxides 530a and 530c are preferably smaller than the electron affinities of the oxide 530b.

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

Specifically, the oxide 530a and the oxide 530b, and the oxide 530b and the oxide 530c have a common element (main component) other than oxygen, thereby forming a mixed layer with a low defect level density. be able to. For example, when the oxide 530b is an In--Ga--Zn oxide, the oxides 530a and 530c may be In--Ga--Zn oxide, Ga--Zn oxide, gallium oxide, or the like.

At this time, the main path of carriers is the oxide 530b. When the oxides 530a and 530c have the above structures, defect level densities at the interfaces between the oxides 530a and 530b and between the oxides 530b and 530c can be reduced. Therefore, the influence of interface scattering on carrier conduction is reduced, and the transistor 500 can obtain a high on-state current.

A conductor 542 (a conductor 542a and a conductor 542b) functioning as a source electrode and a drain electrode is provided over the oxide 530b. Conductors 542 include aluminum, chromium, copper, silver, gold, platinum, tantalum, nickel, titanium, molybdenum, tungsten, hafnium, vanadium, niobium, manganese, magnesium, zirconium, beryllium, indium, ruthenium, iridium, strontium, It is preferable to use a metal element selected from lanthanum, an alloy containing the metal elements described above, or an alloy combining the metal elements described above. For example, tantalum nitride, titanium nitride, tungsten, nitride containing titanium and aluminum, nitride containing tantalum and aluminum, ruthenium oxide, ruthenium nitride, oxide containing strontium and ruthenium, oxide containing lanthanum and nickel, and the like are used. is preferred. Also, tantalum nitride, titanium nitride, nitrides containing titanium and aluminum, nitrides containing tantalum and aluminum, ruthenium oxide, ruthenium nitride, oxides containing strontium and ruthenium, and oxides containing lanthanum and nickel are difficult to oxidize. It is preferable because it is a conductive material or a material that maintains conductivity even after absorbing oxygen.

Further, as shown in FIG. 11A, regions 543 (regions 543a and 543b) are formed as low-resistance regions at the interface between the oxide 530 and the conductor 542 and in the vicinity thereof in some cases. be. At this time, the region 543a functions as one of the source region and the drain region, and the region 543b functions as the other of the source region and the drain region. A channel formation region is formed in a region sandwiched between the regions 543a and 543b.

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

An insulator 544 is provided to cover the conductor 542 and suppress oxidation of the conductor 542 . At this time, the insulator 544 may be provided so as to cover the side surface of the oxide 530 and be in contact with the insulator 524 .

As the insulator 544, a metal oxide containing one or more selected from hafnium, aluminum, gallium, yttrium, zirconium, tungsten, titanium, tantalum, nickel, germanium, magnesium, or the like can be used. can.

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

The insulator 550 functions as a gate insulating film. Insulator 550 is preferably placed in contact with the inside (top and sides) of oxide 530c. The insulator 550 is preferably formed using an insulator from which oxygen is released by heating. For example, in temperature programmed desorption spectroscopy (TDS analysis), the desorption amount of oxygen in terms of oxygen molecules is 1.0×10 ¹⁸ atoms/cm ³ or more, preferably 1.0×10 ¹⁹ . It is an oxide film with a concentration of atoms/cm ³ or more, more preferably 2.0×10 ¹⁹ atoms/cm ³ or 3.0×10 ²⁰ atoms/cm ³ . The surface temperature of the film during the TDS analysis is preferably in the range of 100° C. or higher and 700° C. or lower.

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

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

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

Although the conductor 560 functioning as a gate electrode has a two-layer structure in FIGS. 11A and 11B, it may have a single-layer structure or a stacked structure of three or more layers.

The conductor 560a has a function of suppressing diffusion of impurities such as hydrogen atoms, hydrogen molecules, water molecules, nitrogen atoms, nitrogen molecules, nitrogen oxide molecules (such as N ₂ O, NO, NO ₂ ), and copper atoms. Materials are preferably used. Alternatively, a conductive material having a function of suppressing diffusion of oxygen (eg, at least one of oxygen atoms and oxygen molecules) is preferably used. Since the conductor 560a has a function of suppressing diffusion of oxygen, oxygen contained in the insulator 550 can suppress oxidation of the conductor 560b and a decrease in conductivity. As the conductive material having a function of suppressing diffusion of oxygen, tantalum, tantalum nitride, ruthenium, ruthenium oxide, or the like is preferably used, for example.

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

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

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

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

When miniaturizing a semiconductor device, it is required to shorten the gate length, but it is necessary to prevent the conductivity of the conductor 560 from being lowered. Therefore, when the film thickness of the conductor 560 is increased, the conductor 560 can have a shape with a high aspect ratio. In this embodiment mode, since the conductor 560 is embedded in the opening of the insulator 580, the conductor 560 can be formed without collapsing during the process even if the conductor 560 has a high aspect ratio. can be done.

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

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

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

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

In addition, the conductors 540 a and 540 b are arranged in openings formed in the insulators 581 , 574 , 580 , and 544 . The conductor 540a and the conductor 540b are provided to face each other with the conductor 560 interposed therebetween. The conductors 540a and 540b function as plugs or wirings connected to the transistor 500 .

With the use of this structure, variation in electrical characteristics can be suppressed and reliability can be improved in a semiconductor device including a transistor including an oxide semiconductor. Alternatively, a transistor including an oxide semiconductor with high on-state current can be provided. Alternatively, a transistor including an oxide semiconductor with low off-state current can be provided. Alternatively, a semiconductor device with reduced power consumption can be provided. Alternatively, a semiconductor device including a transistor including an oxide semiconductor can be miniaturized or highly integrated.

Note that the transistor 500 of the semiconductor device described in this embodiment is not limited to the above structure. Structural examples that can be used for the transistor 500 are described below.

<Transistor Structure Example 1>
A structural example of the transistor 510A is described with reference to FIGS. FIG. 12A is a top view of the transistor 510A. FIG. 12(B) is a cross-sectional view of the portion indicated by the dashed line L1-L2 in FIG. 12(A). FIG. 12(C) is a cross-sectional view of the portion indicated by the one-dot chain line W1-W2 in FIG. 12(A). Note that in the top view of FIG. 12A, some elements are omitted for clarity of illustration.

12A, 12B, and 12C, the transistor 510A and the insulators 511, 512, 514, 516, 580, 582, and 582 functioning as interlayer films. A body 584 is shown. Also shown are conductors 546 (conductors 546a and 546b) that are electrically connected to the transistor 510A and function as contact plugs.

The transistor 510A includes a conductor 560 (a conductor 560a and a conductor 560b) functioning as a gate electrode, an insulator 550 functioning as a gate insulating film, and an oxide 530 having a region where a channel is formed (an oxide 530a). , oxide 530b, and oxide 530c);

Further, in the transistor 510A illustrated in FIG. 12, the oxide 530c, the insulator 550, and the conductor 560 are placed in an opening provided in the insulator 580 with the insulator 574 interposed therebetween. In addition, oxide 530c, insulator 550, and conductor 560 are placed between conductors 542a and 542b.

The insulators 511 and 512 function as interlayer films.

The interlayer film may be silicon oxide, silicon oxynitride, silicon nitride oxide, aluminum oxide, hafnium oxide, tantalum oxide, zirconium oxide, lead zirconate titanate (PZT), strontium titanate (SrTiO ₃ ) or (Ba, Sr). Insulators such as TiO ₃ (BST) can be used in single layers or stacks. Alternatively, aluminum oxide, bismuth oxide, germanium oxide, niobium oxide, silicon oxide, titanium oxide, tungsten oxide, yttrium oxide, or zirconium oxide may be added to these insulators. Alternatively, these insulators may be nitrided. Silicon oxide, silicon oxynitride, or silicon nitride may be stacked over the above insulator.

For example, the insulator 511 preferably functions as a barrier film that prevents impurities such as water or hydrogen from entering the transistor 510A from the substrate side. Therefore, the insulator 511 is preferably made of an insulating material that has a function of suppressing diffusion of impurities such as hydrogen atoms, hydrogen molecules, water molecules, and copper atoms (the impurities are less likely to permeate). Alternatively, it is preferable to use an insulating material that has a function of suppressing the diffusion of oxygen (eg, at least one of oxygen atoms, oxygen molecules, and the like) (the above-described oxygen hardly permeates). Alternatively, for example, aluminum oxide, silicon nitride, or the like may be used as the insulator 511 . With this structure, impurities such as hydrogen and water can be prevented from diffusing from the substrate side of the insulator 511 toward the transistor 510A side.

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

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

The insulator 514 and the insulator 516 function as interlayer films similarly to the insulator 511 or the insulator 512 . For example, the insulator 514 preferably functions as a barrier film that prevents impurities such as water or hydrogen from entering the transistor 510A from the substrate side. With this structure, impurities such as hydrogen and water can be prevented from diffusing from the substrate side of the insulator 514 toward the transistor 510A side. Also, for example, the insulator 516 preferably has a lower dielectric constant than the insulator 514 . By using a material with a low dielectric constant as the interlayer film, the parasitic capacitance generated between wirings can be reduced.

Further, the insulator 522 preferably has a barrier property. Since the insulator 522 has a barrier property, it functions as a layer that prevents impurities such as hydrogen from entering the transistor 510A from the periphery of the transistor 510A.

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

For example, insulator 521 is preferably thermally stable. For example, since silicon oxide and silicon oxynitride are thermally stable, an insulator of a high-k material and the insulator 522 are combined to form a thermally stable laminated structure with a high relative dielectric constant. can be done.

Oxide 530 having a region functioning as a channel forming region includes oxide 530a, oxide 530b over oxide 530a, and oxide 530c over oxide 530b. By providing the oxide 530a under the oxide 530b, diffusion of impurities from a structure formed below the oxide 530a to the oxide 530b can be suppressed. In addition, by providing the oxide 530c over the oxide 530b, diffusion of impurities from a structure formed above the oxide 530c to the oxide 530b can be suppressed. As the oxide 530, an oxide semiconductor which is one of the metal oxides described above can be used.

Note that the oxide 530c is preferably provided in the opening provided in the insulator 580 with the insulator 574 interposed therebetween. When the insulator 574 has a barrier property, diffusion of impurities from the insulator 580 into the oxide 530 can be suppressed.

One of the conductors 542 functions as a source electrode and the other functions as a drain electrode.

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

Also, although a single-layer structure is shown in FIG. 12, a laminated structure of two or more layers may be used. For example, a tantalum nitride film and a tungsten film are preferably stacked. Alternatively, a titanium film and an aluminum film may be stacked. A two-layer structure in which an aluminum film is stacked over a tungsten film, a two-layer structure in which a copper film is stacked over a copper-magnesium-aluminum alloy film, a two-layer structure in which a copper film is stacked over a titanium film, a two-layer structure in which a copper film is stacked over a titanium film, A two-layer structure in which copper films are stacked may be used.

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

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

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

By having the barrier layer, the selection of materials for the conductor 542 can be expanded. For example, the conductor 542 can be made of a material having low oxidation resistance but high conductivity, such as tungsten or aluminum. Alternatively, for example, a conductor that can be easily formed into a film or processed can be used.

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

As transistors are miniaturized and highly integrated, thinning of the gate insulating film may cause problems such as leakage current. In that case, the insulator 550 may have a laminated structure. By making the insulator that functions as the gate insulating film a laminated structure of a high-k material and a thermally stable material, it is possible to reduce the gate potential during transistor operation while maintaining the physical film thickness. becomes. Moreover, it is possible to obtain a laminated structure that is thermally stable and has a high dielectric constant.

A conductor 560 functioning as a gate electrode has a conductor 560a and a conductor 560b over the conductor 560a. For the conductor 560a, a conductive material having a function of suppressing diffusion of impurities such as hydrogen atoms, hydrogen molecules, water molecules, and copper atoms is preferably used. Alternatively, a conductive material having a function of suppressing diffusion of oxygen (eg, at least one of oxygen atoms and oxygen molecules) is preferably used. In this specification, the function of suppressing the diffusion of impurities or oxygen means the function of suppressing the diffusion of either one or all of the impurities or oxygen.

Since the conductor 560a has a function of suppressing the diffusion of oxygen, the material selectivity of the conductor 560b can be improved. In other words, with the presence of the conductor 560a, oxidation of the conductor 560b is suppressed, and a decrease in conductivity can be prevented.

As the conductive material having a function of suppressing diffusion of oxygen, tantalum, tantalum nitride, ruthenium, ruthenium oxide, or the like is preferably used, for example. An oxide semiconductor that can be used as the oxide 530 can be used as the conductor 560a. In that case, by forming the conductor 560b by a sputtering method, the electric resistance value of the conductor 560a can be lowered and the conductor 560a can be a conductor. This can be called an OC (Oxide Conductor) electrode.

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

An insulator 574 is placed between insulator 580 and transistor 510A. For the insulator 574, an insulating material having a function of suppressing diffusion of impurities such as water or hydrogen and oxygen is preferably used. For example, it is preferable to use aluminum oxide or hafnium oxide. In addition, metal oxides such as magnesium oxide, gallium oxide, germanium oxide, yttrium oxide, zirconium oxide, lanthanum oxide, neodymium oxide, or tantalum oxide, silicon nitride oxide, or silicon nitride can also be used.

With the insulator 574, impurities such as water and hydrogen contained in the insulator 580 can be prevented from diffusing into the oxide 530b through the oxide 530c and the insulator 550. FIG. In addition, oxidation of the conductor 560 due to excess oxygen in the insulator 580 can be suppressed.

The insulator 580, the insulator 582, and the insulator 584 function as interlayer films.

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

Insulators 580 and 584 preferably have lower dielectric constants than insulator 582, like insulator 516. By using a material with a low dielectric constant as the interlayer film, the parasitic capacitance generated between wirings can be reduced.

Transistor 510A may also be electrically connected to other structures through plugs or wires, such as conductor 546 embedded in insulator 580, insulator 582, and insulator 584. FIG.

As a material of the conductor 546, a single layer or a stacked layer of a conductive material such as a metal material, an alloy material, a metal nitride material, or a metal oxide material can be used. For example, it is preferable to use a high-melting-point material such as tungsten or molybdenum that has both heat resistance and conductivity. Alternatively, it is preferably made of a low-resistance conductive material such as aluminum or copper. Wiring resistance can be reduced by using a low-resistance conductive material.

For example, the conductor 546 has a layered structure of tantalum nitride or the like, which is a conductor having a barrier property against hydrogen and oxygen, and tungsten, which has high conductivity, so that the conductivity of the wiring is increased. Diffusion of impurities from the outside can be suppressed while holding.

With the above structure, a semiconductor device including a transistor including an oxide semiconductor with high on-state current can be provided. Alternatively, a semiconductor device including a transistor including an oxide semiconductor with low off-state current can be provided. Alternatively, it is possible to provide a semiconductor device in which variation in electrical characteristics is suppressed, stable electrical characteristics are obtained, and reliability is improved.

<Transistor structure example 2>
A structural example of the transistor 510B is described with reference to FIGS. FIG. 13A is a top view of the transistor 510B. FIG. 13(B) is a cross-sectional view of the portion indicated by the dashed line L1-L2 in FIG. 13(A). FIG. 13(C) is a cross-sectional view of the portion indicated by the dashed-dotted line W1-W2 in FIG. 13(A). Note that in the top view of FIG. 13A, some elements are omitted for clarity.

Transistor 510B is a variation of transistor 510A. Therefore, in order to avoid repetition of description, differences from the transistor 510A are mainly described.

The transistor 510B has a region where the conductor 542 (the conductor 542a and the conductor 542b) overlaps with the oxide 530c, the insulator 550, and the conductor 560. FIG. With such a structure, a transistor with high on-state current can be provided. Further, a transistor with high controllability can be provided.

A conductor 560 functioning as a gate electrode has a conductor 560a and a conductor 560b over the conductor 560a. For the conductor 560a, a conductive material having a function of suppressing diffusion of impurities such as hydrogen atoms, hydrogen molecules, water molecules, and copper atoms is preferably used. Alternatively, a conductive material having a function of suppressing diffusion of oxygen (eg, at least one of oxygen atoms and oxygen molecules) is preferably used.

Since the conductor 560a has a function of suppressing the diffusion of oxygen, the material selectivity of the conductor 560b can be improved. In other words, with the presence of the conductor 560a, oxidation of the conductor 560b is suppressed, and a decrease in conductivity can be prevented.

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

By providing the insulator 574, oxidation of the conductor 560 can be suppressed. In addition, with the insulator 574, water and impurities such as hydrogen contained in the insulator 580 can be prevented from diffusing into the transistor 510B.

An insulator 576 (an insulator 576 a and an insulator 576 b ) having a barrier property may be placed between the conductor 546 and the insulator 580 . By providing the insulator 576, oxygen in the insulator 580 can be prevented from reacting with the conductor 546 and oxidation of the conductor 546 can be suppressed.

In addition, by providing the insulator 576 having a barrier property, the selection range of conductor materials used for plugs and wirings can be widened. For example, a semiconductor device with low power consumption can be provided by using a metal material having a property of absorbing oxygen and having high conductivity for the conductor 546 . Specifically, a material such as tungsten or aluminum that has low oxidation resistance but high conductivity can be used. Alternatively, for example, a conductor that can be easily formed into a film or processed can be used.

<Transistor structure example 3>
A structural example of the transistor 510C is described with reference to FIGS. FIG. 14A is a top view of the transistor 510C. FIG. 14(B) is a cross-sectional view of the portion indicated by the dashed line L1-L2 in FIG. 14(A). FIG. 14(C) is a cross-sectional view of the portion indicated by the one-dot chain line W1-W2 in FIG. 14(A). Note that in the top view of FIG. 14A, some elements are omitted for clarity.

Transistor 510C is a variation of transistor 510A. Therefore, in order to avoid repetition of description, differences from the transistor 510A are mainly described.

A transistor 510C illustrated in FIG. 14 has a conductor 547a between a conductor 542a and an oxide 530b, and a conductor 547b between a conductor 542b and an oxide 530b. Here, the conductor 542a (conductor 542b) has a region extending over the top surface of the conductor 547a (conductor 547b) and the side surface on the conductor 560 side and in contact with the top surface of the oxide 530b. Here, a conductor that can be used for the conductor 542 may be used as the conductor 547 . Furthermore, the film thickness of the conductor 547 is preferably at least thicker than that of the conductor 542 .

With the above structure, the transistor 510C illustrated in FIG. 14 can bring the conductor 542 closer to the conductor 560 than the transistor 510A. Alternatively, the conductor 560 can overlap the end of the conductor 542a and the end of the conductor 542b. Thereby, the substantial channel length of the transistor 510C can be shortened, and the on-current and frequency characteristics can be improved.

The conductor 547a (the conductor 547b) preferably overlaps with the conductor 542a (the conductor 542b). With such a structure, the conductor 547a (conductor 547b) functions as a stopper in etching for forming an opening for embedding the conductor 546a (conductor 546b), and overetching of the oxide 530b is prevented. can be prevented.

In addition, the transistor 510C illustrated in FIG. 14 may have a structure in which the insulator 545 is arranged over and in contact with the insulator 544 . The insulator 544 preferably functions as a barrier insulating film that prevents impurities such as water or hydrogen and excess oxygen from entering the transistor 510C from the insulator 580 side. As the insulator 545, the insulator that can be used for the insulator 544 can be used. Alternatively, the insulator 544 may be a nitride insulator such as aluminum nitride, aluminum titanium nitride, titanium nitride, silicon nitride, or silicon nitride oxide.

<Transistor structure example 4>
A structural example of the transistor 510D is described with reference to FIGS. FIG. 15A is a top view of the transistor 510D. FIG. 15(B) is a cross-sectional view of the portion indicated by the dashed line L1-L2 in FIG. 15(A). FIG. 15(C) is a cross-sectional view of the portion indicated by the dashed line W1-W2 in FIG. 15(A). Note that in the top view of FIG. 15A, some elements are omitted for clarity.

Transistor 510D is a variation of the above transistor. Therefore, in order to avoid repetition of description, differences from the above transistor will be mainly described.

15A to 15C, an insulator 550 is provided over the oxide 530c and a metal oxide 552 is provided over the insulator 550. FIG. A conductor 560 is provided over the metal oxide 552 and an insulator 570 is provided over the conductor 560 . An insulator 571 is provided over the insulator 570 .

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

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

In some cases, the metal oxide 552 functions as part of the gate insulating film. Therefore, when silicon oxide, silicon oxynitride, or the like is used for the insulator 550, the metal oxide 552 is preferably a high-k material with a high dielectric constant. With the laminated structure, a laminated structure that is stable against heat and has a high relative dielectric constant can be obtained. Therefore, it is possible to reduce the gate potential applied during transistor operation while maintaining the physical film thickness. Also, the equivalent oxide thickness (EOT) of the insulating layer functioning as the gate insulating film can be reduced.

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

When the metal oxide 552 functions as a gate electrode, the on-state current of the transistor 510D can be improved without weakening the influence of the electric field from the conductor 560. FIG. Alternatively, in the case of functioning as a gate insulating film, the distance between the conductor 560 and the oxide 530 is maintained by the physical thicknesses of the insulator 550 and the metal oxide 552, thereby Leakage current with the oxide 530 can be suppressed. Therefore, by providing the stacked structure of the insulator 550 and the metal oxide 552, the physical distance between the conductor 560 and the oxide 530 and the electric field intensity applied from the conductor 560 to the oxide 530 can be reduced to It can be easily adjusted accordingly.

Specifically, the metal oxide 552 can be used as the metal oxide 552 by reducing the resistance of an oxide semiconductor that can be used for the oxide 530 . Alternatively, metal oxides containing one or more selected from hafnium, aluminum, gallium, yttrium, zirconium, tungsten, titanium, tantalum, nickel, germanium, magnesium, and the like can be used.

In particular, it is preferable to use an insulating layer containing one or both oxides of aluminum and hafnium, such as aluminum oxide, hafnium oxide, or an oxide containing aluminum and hafnium (hafnium aluminate). In particular, hafnium aluminate has higher heat resistance than hafnium oxide film. Therefore, it is preferable because it is difficult to crystallize in the heat history in the subsequent steps. Note that the metal oxide 552 is not an essential component. It may be appropriately designed depending on the required transistor characteristics.

For the insulator 570, an insulating material having a function of suppressing permeation of impurities such as water or hydrogen and oxygen is preferably used. For example, it is preferable to use aluminum oxide or hafnium oxide. Accordingly, oxidation of the conductor 560 by oxygen from above the insulator 570 can be suppressed. In addition, impurities such as water or hydrogen from above the insulator 570 can be prevented from entering the oxide 230 through the conductor 560 and the insulator 550 .

Insulator 571 functions as a hard mask. By providing the insulator 571, when the conductor 560 is processed, the side surface of the conductor 560 is substantially vertical. Preferably, it can be 80 degrees or more and 95 degrees or less.

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

Using the insulator 571 as a hard mask, the insulator 570, the conductor 560, the metal oxide 552, the insulator 550, and part of the oxide 530c are selectively removed so that their sides are substantially flush. and a portion of the oxide 530b surface can be exposed.

Transistor 510D also has regions 531a and 531b on a portion of the exposed oxide 530b surface. One of region 531a or region 531b functions as a source region and the other functions as a drain region.

The regions 531a and 531b are formed by introducing an impurity element such as phosphorus or boron into the exposed surface of the oxide 530b using, for example, ion implantation, ion doping, plasma immersion ion implantation, or plasma treatment. It can be realized by Note that in this embodiment and the like, the term “impurity element” refers to an element other than the main component element.

In addition, after exposing part of the surface of the oxide 530b, a metal film is formed and heat treatment is performed to diffuse an element contained in the metal film into the oxide 530b to form the regions 531a and 531b. You can also

A region of the oxide 530b into which the impurity element is introduced has a lower electrical resistivity. Therefore, the regions 531a and 531b are sometimes referred to as "impurity regions" or "low resistance regions".

By using the insulator 571 and/or the conductor 560 as a mask, the regions 531a and 531b can be formed in a self-aligned manner. Therefore, the region 531a and/or the region 531b does not overlap with the conductor 560, and parasitic capacitance can be reduced. Also, no offset region is formed between the channel forming region and the source/drain region (region 531a or region 531b). By forming the regions 531a and 531b in a self-aligned manner, it is possible to increase the ON current, reduce the threshold voltage, and improve the operating frequency.

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

In addition, the transistor 510D has an insulator 575 on the sides of the insulator 570, the conductor 560, the metal oxide 552, the insulator 550, and the oxide 530c. The insulator 575 is preferably an insulator with a low dielectric constant. For example, silicon oxide, silicon oxynitride, silicon nitride oxide, silicon nitride, silicon oxide to which fluorine is added, silicon oxide to which carbon is added, silicon oxide to which carbon and nitrogen are added, silicon oxide having vacancies, resin, or the like. Preferably. In particular, it is preferable to use silicon oxide, silicon oxynitride, silicon nitride oxide, or silicon oxide having vacancies for the insulator 575 because an excess oxygen region can be easily formed in the insulator 575 in a later step. In addition, silicon oxide and silicon oxynitride are preferable because they are thermally stable. Further, the insulator 575 preferably has a function of diffusing oxygen.

In addition, the transistor 510D has an insulator 575 and an insulator 574 over the oxide 530 . The insulator 574 is preferably deposited using a sputtering method. By using a sputtering method, an insulator containing few impurities such as water or hydrogen can be formed. For example, aluminum oxide may be used as the insulator 574 .

Note that an oxide film formed by sputtering may extract hydrogen from a structure to be formed. Therefore, the insulator 574 absorbs hydrogen and water from the oxide 230 and the insulator 575, whereby the hydrogen concentrations in the oxide 230 and the insulator 575 can be reduced.

<Transistor structure example 5>
A structural example of the transistor 510E is described with reference to FIGS. FIG. 16A is a top view of the transistor 510E. FIG. 16(B) is a cross-sectional view of the portion indicated by the dashed line L1-L2 in FIG. 16(A). FIG. 16(C) is a cross-sectional view of the portion indicated by the dashed-dotted line W1-W2 in FIG. 16(A). Note that in the top view of FIG. 16A, some elements are omitted for clarity.

Transistor 510E is a variation of the above transistor. Therefore, in order to avoid repetition of description, differences from the above transistor will be mainly described.

In FIGS. 16A-16C, the conductor 542 is not provided, and a portion of the exposed oxide 530b surface has regions 531a and 531b. One of region 531a or region 531b functions as a source region and the other functions as a drain region. An insulator 573 is provided between the oxide 530 b and the insulator 574 .

Regions 531 (regions 531a and 531b) shown in FIG. 16 are regions in which the following element is added to the oxide 530b. Region 531 can be formed by using a dummy gate, for example.

Specifically, it is preferable to provide a dummy gate over the oxide 530b and use the dummy gate as a mask to add an element that reduces the resistance of the oxide 530b. That is, the element is added to a region where the oxide 530 does not overlap with the dummy gate, so that a region 531 is formed. Examples of the method for adding the element include an ion implantation method in which an ionized source gas is added after mass separation, an ion doping method in which an ionized source gas is added without mass separation, a plasma immersion ion implantation method, and the like. can be used.

As an element for reducing the resistance of the oxide 530, typically, boron or phosphorus can be mentioned. Alternatively, hydrogen, carbon, nitrogen, fluorine, sulfur, chlorine, titanium, rare gas, or the like may be used. Representative examples of noble gas elements include helium, neon, argon, krypton, and xenon. The concentration of the element may be measured using secondary ion mass spectrometry (SIMS) or the like.

Boron and phosphorus are particularly preferred because they allow the use of equipment in amorphous silicon or low temperature polysilicon production lines. Existing equipment can be diverted, and equipment investment can be suppressed.

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

Specifically, after an insulating film to be the insulator 580 is provided over the insulating film to be the insulator 574, the insulating film to be the insulator 580 is subjected to CMP (Chemical Mechanical Polishing) treatment, whereby the insulator 580 and the insulator 580 are separated from each other. A part of the insulating film is removed to expose the dummy gate. Subsequently, when removing the dummy gate, part of the insulator 573 in contact with the dummy gate is preferably removed. Therefore, the insulator 574 and the insulator 573 are exposed on the side surfaces of the opening provided in the insulator 580, and part of the region 531 provided in the oxide 530b is exposed on the bottom surface of the opening. do. Next, after an oxide film to be the oxide 530c, an insulating film to be the insulator 550, and a conductive film to be the conductor 560 are sequentially formed in the opening, CMP treatment or the like is performed until the insulator 580 is exposed. By removing part of the oxide film to be the oxide 530c, the insulating film to be the insulator 550, and the conductive film to be the conductor 560, the transistor illustrated in FIG. 16 can be formed.

Note that the insulators 573 and 574 are not essential components. It may be appropriately designed depending on the required transistor characteristics.

An existing device can be used for the transistor shown in FIG. 16, and the cost can be reduced because the conductor 542 is not provided.

Note that this embodiment can be implemented in appropriate combination with any of the other embodiments described in this specification.

(Embodiment 3)
In this embodiment, an example of a product image and an electronic device in which the semiconductor device described in the above embodiment can be used will be described.

A semiconductor device according to one embodiment of the present invention can be mounted in various electronic devices. In particular, a semiconductor device according to one embodiment of the present invention can be used as an IC for a control system in an electronic device that is expected to be handled in a high-temperature environment. Examples of electronic devices include, for example, moving bodies such as vehicles, vacuum cleaners, microwave ovens, microwave ovens, rice cookers, water heaters, IH cookers, water servers, cooling and heating appliances including air conditioners, washing machines, dryers, audiovisual equipment and the like.

FIG. 17 shows an example of an electronic device.

FIG. 17A is a diagram showing an automobile 5700 that is an example of a mobile object. The semiconductor device described in the above embodiment mode can be used for a control system that controls devices such as sensors and actuators in the automobile 5700 .

FIG. 17B is a diagram showing an electric two-wheeled vehicle 5800 as an example of a mobile object. The semiconductor device described in the above embodiment can be used in a control system for controlling devices such as sensors and actuators in the electric motorcycle 5800, or in a battery management system.

In the above description, an automobile and an electric two-wheeled vehicle are described as examples of the mobile object, but the mobile object is not limited to an automobile and an electric two-wheeled vehicle. Examples of mobile objects include trains, monorails, ships, and flying objects (helicopters, unmanned aerial vehicles (drones), airplanes, and rockets). can be applied.

FIG. 17C shows a microwave oven 5900 which is an example of an electronic device. The semiconductor device described in the above embodiment can be used for a control IC or the like for controlling a power device for flowing current in the microwave oven 5900 .

FIG. 17D shows an electric refrigerator-freezer 6000 as an example of an electronic device. The semiconductor device described in the above embodiment can be used for a control IC or the like for controlling a power device for flowing current in the electric refrigerator-freezer 6000 .

In this example, a microwave oven and an electric refrigerator-freezer are described as electronic devices, but other electronic devices include, for example, a vacuum cleaner, a microwave oven, a rice cooker, a water heater, an IH cooker, a water server, and an air conditioner. Appliances, washing machines, dryers, audiovisual equipment, etc.

A semiconductor device according to one embodiment of the present invention can operate with high reliability even in a high-temperature environment and can achieve low power consumption. By using the semiconductor device according to one embodiment of the present invention in the various electronic devices described above, it is possible to provide highly reliable electronic devices that can reliably operate in both high-temperature and low-temperature environments. can. In addition, low power consumption of the electronic device can be achieved.

Note that this embodiment can be implemented in appropriate combination with any of the other embodiments described in this specification.

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

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

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

In addition, the content described in the embodiment means the content described using various drawings or the content described using sentences described in the specification in each embodiment.

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

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

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

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

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

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

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

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

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

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

In this specification and the like, "A and B are connected" includes not only direct connection between A and B, but also electrical connection. Here, "A and B are electrically connected" means that when there is an object having some kind of electrical action between A and B, an electric signal can be exchanged between A and B. What to say.

100 Semiconductor device 101 Sensor 102 System control circuit 103 Power control circuit 104 Storage device 105 Arithmetic device 106 Range 107 Range 111 Switch 112 Inverter circuit 113 Transistor 114 Transistor 115 Transistor 116 Transistor 121 Transistor 122 Transistor 123 Inverter circuit 230 Oxide 300 Transistor 500 Transistor 510A transistor 510B transistor 510C transistor 510D transistor 510E transistor 511 insulator 512 insulator 514 insulator 516 insulator 520 insulator 521 insulator 522 insulator 524 insulator 530 oxide 530a oxide 530b oxide 530c oxide 531 region 531a region 531b Region 540a Conductor 540b Conductor 542 Conductor 542a Conductor 542b Conductor 543 Region 543a Region 543b Region 544 Insulator 545 Insulator 546 Conductor 546a Conductor 546b Conductor 547 Conductor 547a Conductor 547b Conductor 550 Insulator 552 Metal oxide 560 Conductor 560a Conductor 560b Conductor 570 Insulator 571 Insulator 573 Insulator 574 Insulator 575 Insulator 576 Insulator 576a Insulator 576b Insulator 580 Insulator 581 Insulator 582 Insulator 584 Insulator 5700 Automobile 5800 Electric motorcycle 5900 Microwave oven 6000 Electric refrigerator/freezer 7000A IC
7000B IC
7001 Lead 7002 Printed board 7003A Circuit part 7003B Circuit part 7004 Mounting board 7031 OS transistor layer 7032 Wiring layer 7033 OS transistor layer

Claims (4)

a sensor, a system control circuit, a power supply control circuit, a storage device, and a processor;
The sensor has a function of outputting the acquired first data signal to the system control circuit,
The system control circuit generates a second data signal for switching between a plurality of voltage levels output by the power supply control circuit, and a second data signal for switching the processor between an active state and a sleep state, according to the first data signal. having a function of outputting a third data signal,
the power control circuit has a function of outputting one of the voltage levels to the storage device according to the second data signal or the third data signal;
1. A semiconductor device, wherein said memory device comprises a transistor having a metal oxide in a channel formation region. In claim 1,
A semiconductor device, wherein the transistor has a gate electrode to which a potential lower than a potential applied to the source of the transistor and a potential applied to the drain of the transistor are applied. In claim 1 or claim 2,
A semiconductor device, wherein the metal oxide contains one or both of In (indium) and Zn (zinc). In any one of claims 1 to 3,
The semiconductor device, wherein the metal oxide contains Ga (gallium).

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