Semiconductor device

Abstract

To provide a semiconductor device which is formed using transistors having the same conductivity type, in which a steady current does not flow, and which can express a high level or a low level using a high power supply potential and a low power supply potential.SOLUTION: The semiconductor device includes a plurality of single-polarity transistors, a capacitor, first and second input terminals, and an output terminal. A signal whose logic is inverted from that of a signal input to the first input terminal is input to the second input terminal. In a circuit configuration called bootstrap in which two transistors having the same conductivity type are connected in series between a high power supply potential and a low power supply potential and a capacitor is provided between an output terminal and a gate of one of the transistors, secure bootstrap can be performed by generating a delay between signals output from the gate of the transistor and the output terminal.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] One aspect of the present invention relates to a logic circuit configured using unipolar transistors.

[0002] Another embodiment of the present invention relates to a semiconductor device. It refers to all devices that can function by utilizing the properties of semiconductors. For example, integrated circuits, chips equipped with integrated circuits, electronic components containing chips in packages, and electronic devices equipped with integrated circuits , which is an example of a semiconductor device.

[0003] It should be noted that one embodiment of the present invention is not limited to the above technical fields. The technical field relates to products, methods, or manufacturing methods. is a process, machine, manufacture, or composition of matter. This concerns the [Background technology]

[0004] High level or low level (High or Low, H or L, 1 or 0, etc.) A circuit that handles digital signals (also known as a digital circuit or logic circuit) CMOS (Complementary Metal Oxide Semiconductor) Semiconductor circuits are widely used.

[0005] In many cases, logic circuits are supplied with high and low power supply potentials, and the high level is the high power supply potential. A low level is expressed using a low power supply potential. For example, n-channel transistors and p-channel transistors formed on a single-crystal silicon substrate It is constructed using a transistor.

[0006] A CMOS circuit consists of n-channel and p-channel transistors between a high power supply potential and a low power supply potential. The circuit has a configuration in which n-channel transistors are connected in series, and the n-channel transistor is conductive. When the p-channel transistor is in the non-conducting state, the n-channel transistor is in the When the p-channel transistor is in a non-conducting state, it is in a conducting state. After the high or low level is determined, no through current flows from the high power supply potential to the low power supply potential (transistor). (excluding the off-state current of the transistor, etc.)

[0007] Here, in the case where both n-channel transistors and p-channel transistors cannot be fabricated, In cases where you want to reduce the transistor manufacturing process to reduce costs, etc. , n-channel transistor or p-channel transistor only (unipolar transistor Logic circuits may be constructed using transistors (also called single-channel transistors). do.

[0008] For example, Patent Documents 1 and 2 disclose a semiconductor device constructed using unipolar transistors. Examples of driving circuits for a display device and a body device are disclosed in Patent Document 1 and Patent Document 2. Two unipolar transistors are connected in series between a high power supply potential and a low power supply potential, and a first signal and The logic (high or low level) of the first signal is inverted and the second signal is generated. A circuit configuration in which a through current does not flow from a high power supply potential to a low power supply potential. The method using a first signal and a second signal that is the inverse of the logic of the first signal is a duplex method. It is sometimes called dual rail.

[0009] In addition, in Patent Documents 1 and 2, the output signal is either high level or low level. However, the problem of not reaching the high or low power supply potential is solved by connecting the output terminal and the gate of one of the transistors. This problem is solved by providing a capacitance between the output terminal and the gate of one of the transistors. The method of providing capacitance between the There is a match.

[0010] On the other hand, transistors having metal oxide in the channel formation region (oxide semiconductor transistors) OS transistors (also called OS transistors) have been attracting attention in recent years. The off-state current is very small, and the source and drain It is a thin film transistor that can apply a high voltage between the Furthermore, the OS transistor can be formed in a high-temperature environment. However, the off-current is unlikely to increase, and the ratio of on-current to off-current is large even in high-temperature environments. A semiconductor device including an OS transistor having such characteristics has high reliability.

[0011] For example, Patent Document 3 discloses a semiconductor device on which peripheral circuits such as a drive circuit and a control circuit are formed. , a semiconductor device having a plurality of memory cells using OS transistors, and a DRAM ( Dynamic Random Access Memory (DRAM) memory cells are For example, a Si transistor formed on a single crystal silicon substrate is disclosed. Peripheral circuits are constructed using transistors, and memory using OS transistors is placed above them. The memory cells can be stacked. By providing it on a single crystal silicon substrate on which the OS is formed, the chip area can be reduced. Since the off-state current of the transistor is extremely small, stored data can be retained for a long time. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] Japanese Patent Application Publication No. 9-246936 [Patent Document 2] Japanese Patent Application Laid-Open No. 2002-328643 [Patent Document 3] Japanese Patent Application Laid-Open No. 2012-256820 Summary of the Invention [Problem to be solved by the invention]

[0013] Patent Documents 1 and 2 disclose a system that uses dual rails and bootstraps to Although it is a logic circuit constructed using polarity transistors, it is similar to a CMOS circuit in that it is Once the high or low level is determined, no through current flows from the high power supply potential to the low power supply potential. (It is also said that no steady-state current flows) and uses a high power supply potential to generate a high level, A circuit is disclosed in which a source potential can be used to represent a low level.

[0014] Here, bootstrap is a transistor with a capacitance between the source and gate. In this case, the gate voltage Vgs of the transistor relative to the source must be sufficiently secured. It is preferable that the gate voltage Vgs of the transistor with respect to the source is not sufficiently secured. Otherwise, the high level may not rise to the high power supply potential, or the low level may not rise to the low power supply potential. However, there were cases where the value did not decrease completely.

[0015] In Patent Documents 1 and 2, the source of a transistor is electrically connected to an output terminal. For example, a capacitor is provided between the source and gate of the transistor. When a capacitance load is connected, the potential of the output terminal may rise to a high power supply potential when it is at a high level. When the voltage is low, it may not rise to the low power supply potential. Ta.

[0016] One aspect of the present invention is a logic circuit configured using unipolar transistors, When no current flows and the output is at a high level, the potential of the output terminal rises to the high power supply potential, and the output goes low. The objective is to provide a logic circuit that, when the output terminal voltage drops to the low power supply voltage, Alternatively, one embodiment of the present invention is a semiconductor device including unipolar transistors. When a steady-state current does not flow and the output is at a high level, the potential of the output terminal is high. When the output is at a low level, the potential of the output terminal drops to the low power supply potential. An object of the present invention is to provide a semiconductor device.

[0017] It should be noted that one embodiment of the present invention does not necessarily have to solve all of the above problems, but at least It is enough if it can solve one problem. Also, the description of the problem above may not be sufficient if other problems exist. Other issues than these are not covered by the description, claims, drawings, etc. This becomes clear from the description, claims, drawings, etc. It is possible to extract issues other than these. [Means for solving the problem]

[0018] One embodiment of the present invention is a semiconductor device including first to eighth transistors, first and second capacitors, and first and second capacitors. and a second wiring, first and second input terminals, and first and second output terminals. One of the source and the drain of the first transistor is electrically connected to the first wiring. The other of the source or drain of the first transistor is connected to the source or drain of the second transistor. or drain, one terminal of the first capacitance element, and the first output terminal. The other of the source and the drain of the second transistor is electrically connected to the second wiring. The gate of the first transistor is connected to the gate of the fourth transistor, the source of the eighth transistor, one of the source and drain of the seventh transistor, one of the source and drain of the second capacitor one terminal of the second transistor and the gate of the sixth transistor are electrically connected to the The gate of the fourth transistor is connected to the other terminal of the first capacitance element, the source or drain of the fourth transistor, one of the source and drain of the third transistor, and the gate of the eighth transistor; and electrically connected to the gate of the fifth transistor. The other of the source and drain of the third transistor is electrically connected to the first wiring. The other of the drains is electrically connected to the second wiring, and the gate of the third transistor is connected to the second input. The other of the source and the drain of the eighth transistor is electrically connected to the first output terminal. The other of the source and the drain of the seventh transistor is electrically connected to the second wiring. The gate of the seventh transistor is electrically connected to the first input terminal. One of the source and the drain of the fifth transistor is electrically connected to the first wiring. The other of the source or drain of the transistor is connected to the source or drain of a sixth transistor. the other terminal of the second capacitance element and the second output terminal; The other of the source and the drain of the transistor is electrically connected to a second wiring.

[0019] In the above embodiment, the first to eighth transistors are n-channel transistors.

[0020] In the above embodiment, the first to eighth transistors each have a channel formation region formed of a metal oxide It has.

[0021] In one embodiment of the present invention, a semiconductor device including first to sixth transistors, first and second capacitors, and a third a semiconductor device having first and second wirings, first and second input terminals, and first and second output terminals; The first transistor is a semiconductor device. One of the source and the drain of the first transistor is electrically connected to the first wiring. The other of the source or drain of the first transistor is connected to the source of the second transistor. one of the source and drain of the fourth transistor, the gate of the fourth transistor, one terminal of the first capacitance element, and and a source or drain of the second transistor electrically connected to the first output terminal. The gate of the first transistor is electrically connected to the second wiring. one of the source or drain of the fifth transistor, one of the source or drain of the second transistor One terminal of the capacitance element and the second output terminal are electrically connected to the second transistor. The gate is connected to one of the source and drain of the third transistor and the other of the first capacitance element. The gate of the third transistor is electrically connected to the second wiring. The other of the source and the drain of the third transistor is electrically connected to the second input terminal. The other of the source and the drain of the fourth transistor is electrically connected to the first wiring. The other of the source and the drain of the fifth transistor is electrically connected to the second wiring. The gate of the fifth transistor is connected to one of the source and drain of the sixth transistor, and The gate of the sixth transistor is electrically connected to the other terminal of the second capacitance element. The other of the source and the drain of the sixth transistor is electrically connected to the first input terminal and electrically connected to each other.

[0022] In the above embodiment, the first to sixth transistors are n-channel transistors.

[0023] In the above embodiment, the first to sixth transistors each have a channel formation region formed of a metal oxide It has.

[0024] Furthermore, one embodiment of the present invention is a semiconductor device including first to tenth transistors, first and second capacitors, A semiconductor device having first and second wiring, first to fourth input terminals, and first and second output terminals. The first transistor is a semiconductor device. One of the source and the drain of the first transistor is electrically connected to the first wiring. The other of the source or drain of the first transistor is connected to the source of the second transistor. One of the source and drain terminals, one terminal of the first capacitance element, and the first output terminal are electrically connected to each other. the other of the source and drain of the second transistor is electrically connected to the second wiring. The gate of the first transistor is connected to the gate of the fifth transistor, the gate of the tenth transistor, one of the source or drain of the ninth transistor, one of the source or drain of the ninth transistor, One terminal of the second capacitance element and the gate of the seventh transistor are electrically connected to the second The gate of the transistor is connected to the other terminal of the first capacitance element, the source of the fourth transistor, or one of the drains of the third transistor, one of the source or drain of the fifth transistor one of the source and drain of the tenth transistor, the gate of the sixth transistor, The other of the source and drain of the fifth transistor is electrically connected to the gate of the The other of the source and the drain of the fourth transistor is electrically connected to the second wiring. The other of the source and drain of the third transistor is electrically connected to the second wiring. The gate of the fourth transistor is electrically connected to the fourth input terminal, and the gate of the fourth transistor is electrically connected to the fourth input terminal. The gate of the third transistor is electrically connected to the second input terminal. The other of the source and the drain is electrically connected to the first wiring. The other of the source and drain of the eighth transistor is electrically connected to the source and drain of the eighth transistor. The other of the source and the drain of the eighth transistor is electrically connected to the second wiring. The gate of the ninth transistor is electrically connected to the third input terminal, and the gate of the eighth transistor is electrically connected to the third input terminal. The gate of the sixth transistor is electrically connected to the first input terminal. One of the drains is electrically connected to the first wiring and is the source or drain of the sixth transistor. The other terminal of the second capacitor is connected to one of the source and drain of the seventh transistor. a source or drain of a seventh transistor electrically connected to the second output terminal; The other end of the pin is electrically connected to the second wiring.

[0025] In the above embodiment, the first to tenth transistors are n-channel transistors.

[0026] In the above embodiment, the first to tenth transistors each have a metal oxide layer in a channel formation region. To have something.

[0027] Furthermore, one embodiment of the present invention is a semiconductor device including first to tenth transistors, first and second capacitors, A semiconductor device having first and second wiring, first to fourth input terminals, and first and second output terminals. The first transistor is a semiconductor device. One of the source and the drain of the first transistor is electrically connected to the first wiring. The other of the source or drain of the first transistor is connected to the source of the second transistor. One of the source and drain terminals, one terminal of the first capacitance element, and the first output terminal are electrically connected to each other. the other of the source and drain of the second transistor is electrically connected to the second wiring. The gate of the first transistor is connected to the gate of the fifth transistor, the gate of the tenth transistor, one of the source or drain of the eighth transistor, one of the source or drain of the eighth transistor, One of the source and drain of the 9 transistor, one terminal of the second capacitance element, and The gate of the second transistor is electrically connected to the gate of the first capacitor element. the other terminal of the transistor, one of the source or drain of the fourth transistor, one of the source and drain of the tenth transistor, the gate of the sixth transistor, The other of the source and drain of the fifth transistor is electrically connected to the gate of the The other of the source and drain of the fourth transistor is electrically connected to the third wiring. the source or drain of the third transistor. The other of the source and drain of the fourth transistor is electrically connected to the second wiring, and the gate of the fourth transistor is , the gate of the third transistor is electrically connected to the second input terminal. The other of the source and the drain of the tenth transistor is electrically connected to the first wiring. The other of the source and the drain of the eighth transistor is electrically connected to the second wiring. The other of the source and the drain of the ninth transistor is electrically connected to the second wiring. The gate of the eighth transistor is electrically connected to the first input terminal, and the gate of the ninth transistor is electrically connected to the first input terminal. The gate of the sixth transistor is electrically connected to the third input terminal. One of the drains is electrically connected to the first wiring and is the source or drain of the sixth transistor. The other terminal of the second capacitor is connected to one of the source and drain of the seventh transistor. a source or drain of a seventh transistor electrically connected to the second output terminal; The other end of the pin is electrically connected to the second wiring.

[0028] In the above embodiment, the first to tenth transistors are n-channel transistors.

[0029] In the above embodiment, the first to tenth transistors each have a metal oxide layer in a channel formation region. To have something.

[0030] One embodiment of the present invention is a semiconductor device including first to eighth transistors, first and second capacitors, and first and second capacitors. and a second wiring, first and second input terminals, and first and second output terminals. One of the source and the drain of the first transistor is electrically connected to the first wiring. The other of the source or drain of the first transistor is connected to the source or drain of the second transistor. or drain, one terminal of the first capacitance element, and the first output terminal. The other of the source and the drain of the second transistor is electrically connected to the second wiring. The gate of the first transistor is connected to the gate of the fourth transistor, the source of the eighth transistor, one of the source and drain of the seventh transistor, one of the source and drain of the second capacitor one terminal of the second transistor and the gate of the sixth transistor are electrically connected to the The gate of the fourth transistor is connected to the other terminal of the first capacitance element, the source or drain of the fourth transistor, one of the source and drain of the third transistor, and the gate of the eighth transistor; and electrically connected to the gate of the fifth transistor. The other of the source and drain of the third transistor is electrically connected to the first wiring. The other of the drains is electrically connected to the second wiring, and the gate of the third transistor is connected to the second input. The other of the source and the drain of the eighth transistor is electrically connected to the first output terminal. The other of the source and the drain of the seventh transistor is electrically connected to the second wiring. The gate of the seventh transistor is electrically connected to the first input terminal. One of the source and the drain of the fifth transistor is electrically connected to the first wiring. The other of the source or drain of the transistor is connected to the source or drain of a sixth transistor. the other terminal of the second capacitance element and the second output terminal; The other of the source and the drain of the transistor is electrically connected to the second wiring. A first potential is supplied to the line, and a second potential is supplied to the second wiring, and the second potential is higher than the first potential. The first input terminal is connected to a first signal, and the second input terminal is connected to a second signal. The second signal is the inverted logic of the first signal.

[0031] In the above embodiment, the first to eighth transistors are n-channel transistors.

[0032] In the above embodiment, the first to eighth transistors each have a channel formation region formed of a metal oxide It has.

[0033] In one embodiment of the present invention, a semiconductor device including first to sixth transistors, first and second capacitors, and a third a semiconductor device having first and second wirings, first and second input terminals, and first and second output terminals; The first transistor is a semiconductor device. One of the source and the drain of the first transistor is electrically connected to the first wiring. The other of the source or drain of the first transistor is connected to the source of the second transistor. one of the source and drain of the fourth transistor, the gate of the fourth transistor, one terminal of the first capacitance element, and and a source or drain of the second transistor electrically connected to the first output terminal. The gate of the first transistor is electrically connected to the second wiring. one of the source or drain of the fifth transistor, one of the source or drain of the second transistor One terminal of the capacitance element and the second output terminal are electrically connected to the second transistor. The gate is connected to one of the source and drain of the third transistor and the other of the first capacitance element. The gate of the third transistor is electrically connected to the second wiring. The other of the source and the drain of the third transistor is electrically connected to the second input terminal. The other of the source and the drain of the fourth transistor is electrically connected to the first wiring. The other of the source and the drain of the fifth transistor is electrically connected to the second wiring. The gate of the fifth transistor is connected to one of the source and drain of the sixth transistor, and The gate of the sixth transistor is electrically connected to the other terminal of the second capacitance element. The other of the source and the drain of the sixth transistor is electrically connected to the first input terminal The first wiring is supplied with a first potential, and the second wiring is supplied with a second potential. The second potential is higher than the first potential, and a first signal is input to the first input terminal. A second signal is input to the second input terminal, and the second signal is a signal in which the logic of the first signal is inverted. is.

[0034] In the above embodiment, the first to sixth transistors are n-channel transistors.

[0035] In the above embodiment, the first to sixth transistors each have a channel formation region formed of a metal oxide It has.

[0036] Furthermore, one embodiment of the present invention is a semiconductor device including first to tenth transistors, first and second capacitors, A semiconductor device having first and second wiring, first to fourth input terminals, and first and second output terminals. The first transistor is a semiconductor device. One of the source and the drain of the first transistor is electrically connected to the first wiring. The other of the source or drain of the first transistor is connected to the source of the second transistor. One of the source and drain terminals, one terminal of the first capacitance element, and the first output terminal are electrically connected to each other. the other of the source and drain of the second transistor is electrically connected to the second wiring. The gate of the first transistor is connected to the gate of the fifth transistor, the gate of the tenth transistor, one of the source or drain of the ninth transistor, one of the source or drain of the ninth transistor, One terminal of the second capacitance element and the gate of the seventh transistor are electrically connected to the second The gate of the transistor is connected to the other terminal of the first capacitance element, the source of the fourth transistor, or one of the drains of the third transistor, one of the source or drain of the fifth transistor one of the source and drain of the tenth transistor, the gate of the sixth transistor, The other of the source and drain of the fifth transistor is electrically connected to the gate of the The other of the source and the drain of the fourth transistor is electrically connected to the second wiring. The other of the source and drain of the third transistor is electrically connected to the second wiring. The gate of the fourth transistor is electrically connected to the fourth input terminal, and the gate of the fourth transistor is electrically connected to the fourth input terminal. The gate of the third transistor is electrically connected to the second input terminal. The other of the source and the drain is electrically connected to the first wiring. The other of the source and drain of the eighth transistor is electrically connected to the source and drain of the eighth transistor. The other of the source and the drain of the eighth transistor is electrically connected to the second wiring. The gate of the ninth transistor is electrically connected to the third input terminal, and the gate of the eighth transistor is electrically connected to the third input terminal. The gate of the sixth transistor is electrically connected to the first input terminal. One of the drains is electrically connected to the first wiring and is the source or drain of the sixth transistor. The other terminal of the second capacitor is connected to one of the source and drain of the seventh transistor. a source or drain of a seventh transistor electrically connected to the second output terminal; The other end of the first wiring is electrically connected to a second wiring. A first potential is supplied to the first wiring, and a second potential is supplied to the second wiring. A second potential is applied to the line, the second potential being higher than the first potential, and the first input terminal The first signal is input to the first input terminal, the second signal is input to the second input terminal, and the third signal is input to the third input terminal. The fourth signal is input to the fourth input terminal, and the second signal is the inverse of the logic of the first signal. The fourth signal is a signal obtained by inverting the logic of the third signal, and the fourth signal is a signal obtained by inverting the logic of the third signal.

[0037] In the above embodiment, the first to tenth transistors are n-channel transistors.

[0038] In the above embodiment, the first to tenth transistors each have a metal oxide layer in a channel formation region. To have something.

[0039] Furthermore, one embodiment of the present invention is a semiconductor device including first to tenth transistors, first and second capacitors, A semiconductor device having first and second wiring, first to fourth input terminals, and first and second output terminals. The first transistor is a semiconductor device. One of the source and the drain of the first transistor is electrically connected to the first wiring. The other of the source or drain of the first transistor is connected to the source of the second transistor. One of the source and drain terminals, one terminal of the first capacitance element, and the first output terminal are electrically connected to each other. the other of the source and drain of the second transistor is electrically connected to the second wiring. The gate of the first transistor is connected to the gate of the fifth transistor, the gate of the tenth transistor, one of the source or drain of the eighth transistor, one of the source or drain of the eighth transistor, One of the source and drain of the 9 transistor, one terminal of the second capacitance element, and The gate of the second transistor is electrically connected to the gate of the first capacitor element. the other terminal of the transistor, one of the source or drain of the fourth transistor, one of the source and drain of the tenth transistor, the gate of the sixth transistor, The other of the source and drain of the fifth transistor is electrically connected to the gate of the The other of the source and drain of the fourth transistor is electrically connected to the third wiring. the source or drain of the third transistor. The other of the source and drain of the fourth transistor is electrically connected to the second wiring, and the gate of the fourth transistor is , the gate of the third transistor is electrically connected to the second input terminal. The other of the source and the drain of the tenth transistor is electrically connected to the first wiring. The other of the source and the drain of the eighth transistor is electrically connected to the second wiring. The other of the source and the drain of the ninth transistor is electrically connected to the second wiring. The gate of the eighth transistor is electrically connected to the first input terminal, and the gate of the ninth transistor is electrically connected to the first input terminal. The gate of the sixth transistor is electrically connected to the third input terminal. One of the drains is electrically connected to the first wiring and is the source or drain of the sixth transistor. The other terminal of the second capacitor is connected to one of the source and drain of the seventh transistor. a source or drain of a seventh transistor electrically connected to the second output terminal; The other end of the first wiring is electrically connected to a second wiring. A first potential is supplied to the first wiring, and a second potential is supplied to the second wiring. A second potential is applied to the line, the second potential being higher than the first potential, and the first input terminal The first signal is input to the first input terminal, the second signal is input to the second input terminal, and the third signal is input to the third input terminal. The fourth signal is input to the fourth input terminal, and the second signal is the inverse of the logic of the first signal. The fourth signal is a signal obtained by inverting the logic of the third signal, and the fourth signal is a signal obtained by inverting the logic of the third signal.

[0040] In the above embodiment, the first to tenth transistors are n-channel transistors.

[0041] In the above embodiment, the first to tenth transistors each have a metal oxide layer in a channel formation region. To have something. [Effects of the Invention]

[0042] According to one embodiment of the present invention, a logic circuit is configured using unipolar transistors, When no steady-state current flows and the output is at a high level, the potential of the output terminal rises to the high power supply potential, Provides a logic circuit in which the potential of the output terminal drops to the low power supply potential when the output is at a low level. Alternatively, according to one embodiment of the present invention, a transistor configured using unipolar transistors can be used. Although it is a semiconductor device, when no steady current flows and the output is at a high level, the potential of the output terminal When the voltage at the output terminal rises to the high power supply voltage and the output is at the low level, the voltage at the output terminal falls to the low power supply voltage. Therefore, a semiconductor device can be provided.

[0043] The description of these effects does not preclude the existence of other effects. A form does not necessarily have to have all of these effects. Effects other than these may be included in the specification. It is obvious from the description, claims, drawings, etc. Other effects can be extracted from the claims, drawings, etc. [Brief explanation of the drawings]

[0044] [Figure 1] FIG. 1 is a circuit diagram showing an example of the configuration of a semiconductor device. [Figure 2] FIG. 2 is a timing chart. [Figure 3] FIG. 3 is a circuit diagram showing a configuration example of a semiconductor device. [Figure 4] FIG. 4 is a timing chart. [Figure 5] 5A and 5B are diagrams showing circuit diagram symbols of transistors, and Fig. 5C and Fig. 5D are circuit diagrams showing configuration examples of semiconductor devices. [Figure 6] FIG. 6 is a circuit diagram showing an example of the configuration of a semiconductor device. [Figure 7]FIG. 7 is a circuit diagram showing a configuration example of a semiconductor device. [Figure 8] FIG. 8 is a timing chart. [Figure 9] FIG. 9 is a cross-sectional view showing an example of the configuration of a semiconductor device. [Figure 10] 10A, 10B, and 10C are cross-sectional views showing examples of the structure of a transistor. [Figure 11] 11A is a top view illustrating an example of the structure of a transistor, and FIGS. 11B and 11C are cross-sectional views illustrating an example of the structure of a transistor. [Figure 12] 12A is a top view illustrating an example of the structure of a transistor, and FIGS. 12B and 12C are cross-sectional views illustrating an example of the structure of a transistor. [Figure 13] 13A is a top view illustrating an example of the structure of a transistor, and FIGS. 13B and 13C are cross-sectional views illustrating an example of the structure of a transistor. [Figure 14] 14A is a top view illustrating an example of the structure of a transistor, and FIGS. 14B and 14C are cross-sectional views illustrating an example of the structure of a transistor. [Figure 15] 15A is a top view illustrating an example of the structure of a transistor, and FIGS. 15B and 15C are cross-sectional views illustrating an example of the structure of a transistor. [Figure 16] 16A is a top view illustrating an example of the structure of a transistor, and FIGS. 16B and 16C are cross-sectional views illustrating an example of the structure of a transistor. [Figure 17] 17A and 17B are cross-sectional views showing examples of the structure of a transistor. [Figure 18] FIG. 18 is a cross-sectional view showing an example of the configuration of a semiconductor device. [Figure 19] 19A and 19B are cross-sectional views showing examples of the structure of a transistor. [Figure 20] Fig. 20A is a diagram explaining the classification of IGZO crystal structures. Fig. 20B is a diagram explaining the XRD spectrum of silica glass. Fig. 20C is a diagram explaining the XRD spectrum of crystalline IGZO. Fig. 20D is a diagram explaining the electron microbeam diffraction pattern of crystalline IGZO. DETAILED DESCRIPTION OF THE INVENTION

[0045] Hereinafter, embodiments will be described with reference to the drawings. The present invention may be implemented in any form without departing from the spirit and scope of the present invention. It will be readily apparent to those skilled in the art that various modifications may be made to the design and details of the present invention. However, the present invention should not be construed as being limited to the description of the following embodiments.

[0046] In addition, the following embodiments can be combined as appropriate. When a plurality of configuration examples are shown in one embodiment, the configuration examples may be combined with each other as appropriate. It is possible to do this.

[0047] In addition, in the drawings, etc., the size, thickness of layers, areas, etc. may be exaggerated for clarity. Therefore, the scale is not necessarily limited to the above. The drawings are only a schematic representation of ideal examples. The present invention is not limited to the shapes or values ​​shown in the drawings.

[0048] In addition, in drawings, etc., the same elements or elements having similar functions, elements made of the same material, Alternatively, elements formed at the same time may be given the same reference numerals, and the repeated explanations thereof may be omitted. may be omitted.

[0049] In addition, in this specification and the like, the terms "film" and "layer" are interchangeable. For example, the term "conductive layer" can be changed to the term "conductive film." Alternatively, for example, the term "insulating film" may be changed to "insulating layer." It may be possible to change the term to

[0050] In addition, in this specification, terms indicating placement such as "above" and "below" refer to the positional relationship of components. The relationship is not limited to being "directly above" or "directly below." For example, In the case of the expression "gate electrode on an insulating layer," it is understood that there is no other component between the gate insulating layer and the gate electrode. Do not exclude anything that includes.

[0051] In addition, in this specification, ordinal numbers such as "first," "second," and "third" indicate the order of constituent elements. This is added to avoid confusion and is not intended to limit the number.

[0052] In addition, in this specification and the like, when the same reference numeral is used for a plurality of elements, it is not necessary to particularly distinguish between them. If necessary, use identifiers such as "_1", "_2", "[n]", "[m,n]", etc. For example, the second wiring GL is called wiring GL[2]. Write it down.

[0053] In addition, in this specification, "electrically connected" means "something that has some kind of electrical effect." This includes cases where the device is connected via a " is not subject to any particular restrictions as long as it enables the transmission and reception of electrical signals between connected objects. For example, "things that have some kind of electrical action" include electrodes, wiring, and transistors. These include switching elements, resistor elements, inductors, capacitor elements, and various other functions. Also, even if it is expressed as "electrically connected", it does not necessarily mean that the actual circuit In some cases, there are no physical connections and only wiring is extended.

[0054] In addition, in this specification and the like, the terms "electrode" and "wiring" are used to refer to these components functionally. This is not a limitation. For example, an "electrode" may be used as part of a "wiring." , and vice versa.

[0055] In this specification, a "terminal" in an electric circuit refers to a terminal that is used to input (or It refers to the part where the signal is received (or transmitted) or output. Alternatively, a part of the electrode may function as a terminal.

[0056] Generally, a "capacitance" has a structure in which two electrodes face each other through an insulator (dielectric). In this specification and the like, the term "capacitance element" includes the above-mentioned "capacitance." That is, in this specification, a "capacitance element" refers to a capacitor having two electrodes facing each other with an insulator interposed therebetween. a structure in which two wires face each other through an insulator; This includes cases where two wires are arranged with an insulator between them.

[0057] In this specification, the term "voltage" refers to the difference between a certain potential and a reference potential (for example, ground potential). Therefore, voltage and potential difference can be interchanged. can.

[0058] In this specification, a transistor includes a gate, a drain, and a source. , an element having at least three terminals. drain region or drain electrode) and source (source terminal, source region or source electrode) ) and a channel forming region is formed between the source and drain. In this specification and the like, a channel is formed between the The region refers to the region through which the current mainly flows.

[0059] The source and drain functions may differ depending on the type of transistor used, or the circuit operation. This may be reversed if the direction of the current changes during operation. In the text, the terms source and drain may be used interchangeably.

[0060] Unless otherwise specified, in this specification and the like, the off-state current refers to the current that flows when a transistor is in an off-state. The drain current when the device is in the on state (also known as the non-conducting state or cut-off state). , unless otherwise specified, for n-channel transistors, the gate to source voltage V When gs is lower than the threshold voltage Vth, in a p-channel transistor, This refers to the state in which the gate voltage Vgs is higher than the threshold voltage Vth. The off-state current of a gate-type transistor is the voltage Vgs of the gate to the source when the threshold voltage V This is sometimes called the drain current when it is lower than th.

[0061] In the above description of the off-state current, the drain may be read as the source. The off-state current is the source current when the transistor is in the off state. In this specification and the like, the off-state current is refers to the current that flows between the source and drain when the transistor is in the off state. There is a match.

[0062] In this specification, the on-state current is the current that flows when a transistor is in an on-state (also called a conductive state). It can also refer to the current that flows between the source and drain when the device is in a non-uniform state.

[0063] In this specification, the term "metal oxide" is used in a broad sense. Metal oxides are oxides of metals. Metal oxides are oxide insulators, oxide conductors (transparent oxide conductors, They are classified into oxide semiconductors, etc.

[0064] For example, when a metal oxide is used for a channel formation region of a transistor, the metal oxide is In other words, metal oxides have amplifying, rectifying, and When the metal oxide has at least one switching function, the metal oxide is called a metal oxide semiconductor. (metal oxide semiconductor). Specifically, a transistor having a metal oxide in a channel formation region is called an "oxide semiconductor transistor." Similarly, the above-mentioned “oxide semiconductor transistor” can be called an “OS transistor.” The "transistor using this method" is also a transistor having a metal oxide in a channel formation region.

[0065] In this specification and the like, metal oxides containing nitrogen are also referred to as metal oxides. Metal oxides containing nitrogen are sometimes called metal oxynitrides (met Metal oxides may also be called metal oxynitrides. Details of metal oxides will be explained later. .

[0066] (Embodiment 1) In this embodiment, a configuration example of a semiconductor device according to one embodiment of the present invention will be described. A semiconductor device according to one embodiment of the present invention is configured using unipolar transistors and is connected to a high power supply potential. A logic circuit in which a high level is represented by a low power supply potential and a low level is represented by a low power supply potential. .

[0067] In addition, in the semiconductor device described in this specification, an example using an n-channel transistor However, a p-channel transistor can also be used. The change from a p-channel transistor to a p-channel transistor is easily understood by those skilled in the art. The explanation will be omitted.

[0068] <Configuration Example 1 of Semiconductor Device> FIG. 1 is a circuit diagram showing an example of the configuration of a semiconductor device 10. The semiconductor device 10 is an embodiment of the present invention. The semiconductor device according to the present invention includes transistors 11 to 18 and a capacitor C11. , and a capacitance element C12. The transistors 11 to 18 are n-channel transistors. It is a transistor of the NAND type.

[0069] The semiconductor device 10 includes a wiring VSS_IN to which a low power supply potential VSS is supplied, a wiring VSS_IN to which a high power supply potential VDD the wiring VDD_IN to which the signal SI is supplied, the input terminal SI_IN to which the signal SI is input, and the signal SIB an input terminal SIB_IN to which the signal is input, an output terminal SO_OUT to which the signal SO is output, and , and has an output terminal SOB_OUT for outputting the signal SOB.

[0070] Here, the high power supply potential VDD is a potential higher than the low power supply potential VSS, and the low power supply potential VS S may be a reference potential in the semiconductor device 10. In addition, the signals SI and SI B is a digital signal, and the potential representing the high level of the signal SI and the signal SIB is a high power supply voltage. The potential representing the low level can be the low power supply potential VSS. Furthermore, the signal SIB is a signal obtained by inverting the logic of the signal SI.

[0071] In the semiconductor device 10, one of the source and drain of the transistor 11 is connected to the wiring VS The other of the source and drain of the transistor 11 is electrically connected to the transistor S_IN. One of the source and drain of the transistor 12, one terminal of the capacitance element C11, and and the source or drain of the transistor 12. The other end is electrically connected to the wiring VDD_IN.

[0072] The gate of transistor 11 is connected to the gate of transistor 14, the source of transistor 18, and one of the source and drain of the transistor 17, and the capacitance element C12 and the gate of the transistor 16. The gate of the transistor 12 is connected to the other terminal of the capacitance element C11, the source of the transistor 14, or One of the drains of the transistor 13, one of the source or drain of the transistor 18 The gate of the transistor 11 is electrically connected to the gate of the transistor 15 .

[0073] The other of the source and the drain of the transistor 14 is electrically connected to the wiring VSS_IN. The other of the source and the drain of the transistor 13 is electrically connected to the wiring VDD_IN. The gate of the transistor 13 is electrically connected to the input terminal SIB_IN. The other of the source and the drain of the transistor 18 is electrically connected to the wiring VSS_IN. The other of the source and drain of the transistor 17 is electrically connected to the wiring VDD_IN. The gate of the transistor 17 is electrically connected to the input terminal SI_IN.

[0074] One of the source and the drain of the transistor 15 is electrically connected to the wiring VSS_IN. The other of the source or drain of the transistor 15 is connected to the source or drain of the transistor 16. is connected to one side of the drain, the other terminal of the capacitance element C12, and the output terminal SOB_OUT. The other of the source and drain of the transistor 16 is electrically connected to the wiring VDD_IN and electrically connected to each other.

[0075] Here, the gate of transistor 11, the gate of transistor 14, and the gate of transistor 18 One of the source or drain, one of the source or drain of the transistor 17, the capacitance element The connection between one terminal of the transistor C12 and the gate of the transistor C16 is connected to a node N12. The gate of the transistor 12, the other terminal of the capacitance element C11, One of the source or drain of transistor 14, one of the source or drain of transistor 13 On the other hand, the gate of the transistor 18 and the connection part with the gate of the transistor 15 are connected to the It is called Code N11.

[0076] <Operation example 1 of the semiconductor device> 2 is a timing chart showing an example of the operation of the semiconductor device 10. The potentials of the signal SIB, the node N11, the node N12, the signal SO, and the signal SOB are set to the expected potentials. The period is divided into periods D11 to D14. The threshold voltage of 18 is assumed to be the threshold voltage Vth.

[0077] A period D11 is a period in which the signal SI is at a high level and the signal SIB is at a low level. For the interval D11, a static state is considered as the initial state. Therefore, the transistor 17 is in a conductive state and the node N12 is at a high level. During this period, the potential of the node N12 is lower than the high power supply potential VDD and is approximately equal to the high power supply potential VDD. The value is obtained by subtracting the threshold voltage Vth from the power supply voltage VDD. Therefore, transistor 13 is in a non-conductive state.

[0078] Since the node N12 is at a high level, the transistors 14, 11, and The transistor 16 is in a conductive state, and the node N11 is at a low level. Transistor 18, transistor 15, and transistor 12 are non-conductive.

[0079] The transistor 12 is in a non-conducting state and the transistor 11 is in a conducting state. Therefore, the signal SO is at a low level. Since the transistor 15 is in a non-conductive state, the signal SOB is at a high level. During this period, the potential of the signal SOB is lower than the high power supply potential VDD, similar to the node N12. is the electric potential.

[0080] In the period D12, the signal SI changes from a high level to a low level, and the signal SIB changes from a low level to a The period during which the signal changes from high level to low level (the period during which the signal changes from high level to low level is called the falling edge) the period during which the signal changes from low to high is called the rising period), and This is a period in which the signal SI is at a low level and the signal SIB is at a high level.

[0081] During period D12, transistor 17 changes from a conductive state to a non-conductive state. When transistor 13 changes from a non-conductive state to a conductive state, On the other hand, even if the transistor 17 changes to a non-conductive state, After the node N11 goes high, the node N12 does not go low immediately. , transistor 18 changes to a conductive state, and node N12 goes low.

[0082] When node N11 goes high, transistors 18, 15, and When the node N12 becomes low level, the transistor N12 becomes conductive. Transistor 14, transistor 11, and transistor 16 are non-conductive.

[0083] The transistor 12 is in a conducting state and the transistor 11 is in a non-conducting state. Therefore, the signal SO goes high. Also, the transistor 16 is in a non-conductive state. Since the transistor 15 is in a conductive state, the signal SOB is at a low level.

[0084] Here, after the node N11 becomes high level, until the node N12 becomes low level, The time is a delay time DT12. The node N11 becomes high level, and the transistor 12 Even if node N11 becomes conductive, transistor N11 will not be conductive until node N12 becomes low level. Therefore, the signal SO is in a normal state from the timing when the node N11 becomes high level. It will be delayed and reach a high level.

[0085] The signal SO becomes high level after the timing when the node N11 becomes high level. Therefore, a potential difference occurs between the output terminal SO_OUT and the node N11. If the potential difference is DV12, the potential difference DV12 is The signal SO changes from low to high. Then, due to the capacitive coupling of the capacitive element C11, the potential of the node N11 rises, and the potential of the node N The potential of 11 can be made higher than the high power supply potential VDD.

[0086] When the potential of the node N11 becomes higher than the high power supply potential VDD, the potential of the signal SO is set to the high power supply potential VDD. In addition, the voltage of the node N11 that is higher than the high power supply potential VDD can be The transistors 13 and 14 are transistors with small off-state currents, which will be described later. By using the START signal, the period when the signal SI is at a low level (the period when the signal SIB is at a high level) It can be maintained for a long period of time.

[0087] In a period D13, the signal SI changes from a low level to a high level, and the signal SIB changes to a high level. The period when the signal SI changes from high to low, and the period when the signal SIB changes from high to low, This is the period of the rule.

[0088] During period D13, transistor 17 changes from a non-conductive state to a conductive state. When transistor 13 changes from a conducting state to a non-conducting state, transistor 17 changes to a conducting state. On the other hand, even if the transistor 13 changes to a non-conductive state, After the node N12 becomes high level, the node N11 does not immediately become low level. , the transistor 14 changes to a conductive state, and the node N11 goes low.

[0089] When node N12 goes high, transistors 14, 11, and When the node N11 goes low, the transistor 16 is turned on. Transistor 18, transistor 15, and transistor 12 are non-conductive.

[0090] The transistor 12 is in a non-conducting state and the transistor 11 is in a conducting state. Therefore, the signal SO is at a low level. Since the transistor 15 is in a non-conductive state, the signal SOB goes high.

[0091] Here, after the node N12 becomes high level, until the node N11 becomes low level, The delay time is defined as a delay time DT13. The node N12 becomes high level, and the transistor 16 Even if the node N11 is turned on, the transistor 15 is not turned on until the node N11 is turned low. Therefore, the signal SOB is in a normal state from the timing when the node N12 becomes high level. Then, it becomes high level later.

[0092] The signal SOB becomes high level after the timing when the node N12 becomes high level. Therefore, a potential difference occurs between the output terminal SOB_OUT and the node N12. If the difference is a potential difference DV13, the potential difference DV13 is The signal SOB is also applied between the other terminal of the element C12 and the other terminal of the element C13. When the voltage at node N12 changes to The potential of the node N12 can be made higher than the high power supply potential VDD.

[0093] When the potential of the node N12 becomes higher than the high power supply potential VDD, the potential of the signal SOB becomes higher than the high power supply potential VDD. The potential of the node N12, which is higher than the high power supply potential VDD, can be set to the potential VDD. The potential is applied to the transistor 17 and the transistor 18 by a transistor with a small off-state current, which will be described later. By using a register, the period during which the signal SI is at a high level (the period during which the signal SIB is at a low level) The period of time that the data is stored can be kept for a long period of time.

[0094] In a period D14, the signal SI changes from a high level to a low level, and the signal SIB changes from a low level to a The period when the signal SI changes from low to high level, and the period when the signal SIB changes from low to high level It should be noted that the period D14 is the same as the period D12, and therefore the explanation thereof will be omitted.

[0095] As described above, the semiconductor device 10 is a logic circuit configured using n-channel transistors. A potential is applied between the output terminal SO_OUT and the node N11 by a delay time DT12. By ensuring the difference DV12, it is possible to obtain a more reliable result than the examples disclosed in Patent Document 1 or Patent Document 2. Indeed, the potential of the node N11 can be made higher than the high power supply potential VDD. A potential difference DV13 is generated between the output terminal SOB_OUT and the node N12 during the time DT13. By securing the above, the node can be more reliably secured than in the examples disclosed in Patent Document 1 or Patent Document 2. The potential of N12 can be made higher than the high power supply potential VDD.

[0096] When the signal SO output from the output terminal SO_OUT is at a high level, the voltage of the node N11 is By setting the potential higher than the high power supply potential VDD, the output terminal S When the signal SOB output from OB_OUT is at a high level, it raises the potential of the node N12. By making it higher than the power supply potential VDD, it rises to the high power supply potential VDD. When the signal SOB is at a low level, it drops to the low power supply potential VSS, and the semiconductor device 10 After the high or low level of the signals SO and SOB is determined, It has the feature that no through current flows from the power supply potential VDD to the low power supply potential VSS.

[0097] <Configuration Example 2 of Semiconductor Device> 3 is a circuit diagram showing an example of the configuration of the semiconductor device 20. The semiconductor device 20 is an embodiment of the present invention. The semiconductor device 20 is a semiconductor device according to the present invention, and is a configuration example different from that of the semiconductor device 10. transistors 21 to 26, capacitor C21, and capacitor C22 The transistors 21 to 26 are n-channel transistors. do.

[0098] The semiconductor device 20, like the semiconductor device 10, has a wiring VSS_ IN, wiring to which the high power supply potential VDD is supplied VDD_IN, input terminal to which the signal SI is input SI_IN, an input terminal to which the signal SIB is input, SIB_IN, an output terminal to which the signal SO is output The output terminal SO_OUT is connected to the output terminal SOB_OUT for outputting the signal SOB. , the explanation of the potentials and signals will be omitted to avoid repetition.

[0099] In the semiconductor device 20, one of the source and drain of the transistor 21 is connected to the wiring VS The other of the source and drain of the transistor 21 is electrically connected to the transistor S_IN. One of the source or drain of the transistor 22, the gate of the transistor 24, the capacitance element C2 1 and the output terminal SO_OUT, and the transistor 22 The other of the source and the drain is electrically connected to the wiring VDD_IN.

[0100] The gate of transistor 21 is connected to either the source or drain of transistor 24. One of the source and drain of the resistor 25, one terminal of the capacitance element C22, and the output The gate of the transistor 22 is electrically connected to the terminal SOB_OUT. 3 and the other terminal of the capacitance element C21. The gate of the transistor 23 is electrically connected to the wiring VDD_IN. The other of the source and drain of the transistor 23 is electrically connected to the input terminal SIB_IN. will be done.

[0101] The other of the source and the drain of the transistor 24 is electrically connected to the wiring VSS_IN. The other of the source and the drain of the transistor 25 is electrically connected to the wiring VDD_IN. The gate of transistor 25 is connected to either the source or drain of transistor 26. , and the other terminal of the capacitor C22. The gate of the transistor 26 is electrically connected to the wiring VDD_IN, and the source or drain of the transistor 26 is electrically connected to the wiring VDD_IN. The other end of the drain is electrically connected to the input terminal SI_IN.

[0102] Here, the gate of the transistor 22 and one of the source and drain of the transistor 23 The connection point between the other terminal of the capacitor C21 and the other terminal of the capacitor C21 is called a node N21. The gate of the transistor 25, the source or drain of the transistor 26, and the capacitance element The connection point with the other terminal of the child C22 is called a node N22.

[0103] <Semiconductor Device Operation Example 2> 4 is a timing chart showing an example of the operation of the semiconductor device 20. The potentials of the signal SIB, the node N21, the node N22, the signal SO, and the signal SOB are set to the expected potentials. The period is divided into periods D21 to D24. The threshold voltage of 26 is assumed to be the threshold voltage Vth.

[0104] A period D21 is a period in which the signal SI is at a high level and the signal SIB is at a low level. For the interval D21, a static state is considered as an initial state. The potential of the node N22 is at a high level, the same as the signal SI. The potential of the node N21 is at the low level, the same as the signal SIB. However, the potential of the node N22 during this period is lower than the high power supply potential VDD, and This is the value obtained by subtracting the threshold voltage Vth from the high power supply potential VDD.

[0105] Since node N22 is at a high level, transistor 25 is in a conductive state, and signal SOB However, the potential of the signal SOB during this period is the same as that of the node N22. Similarly, the potential is lower than the high power supply potential VDD. Also, the transistor 21 is in a conductive state.

[0106] Since the node N21 is at a low level, the transistor N22 is in a non-conductive state. Since the transistor 21 is in a conductive state, the signal SO is at a low level. Starter 24 is in a non-conducting state.

[0107] In the period D22, the signal SI changes from a high level to a low level, and the signal SIB changes from a low level to a low level. The period when the signal SI changes from low to high level, and the period when the signal SIB changes from low to high level This is the period of the rule.

[0108] During a period D22, the node N22 changes from a high level to a low level, and the transistor 25 changes from a conductive state to a non-conductive state, and the node N21 changes from a low level to a high level. bell, causing transistor 22 to change from a non-conducting state to a conducting state.

[0109] When transistor 22 changes to a conductive state, signal SO goes high. Even if the resistor 25 changes to a non-conductive state, the signal SOB does not immediately go low. After signal SO goes high, transistor 24 changes to a conductive state and signal SOB goes low. When the signal SOB goes low, the transistor 21 goes non-conductive. It becomes a state.

[0110] Even if the signal SO goes high, the transistors are turned off until the signal SOB goes low. Therefore, the potential of the signal SO is lower than the high power supply potential VDD. After the transistor 21 is turned off, the potential of the signal SO rises again. do.

[0111] On the other hand, after the node N21 changes from low level to high level, the signal SO becomes high level. After the signal SOB changes to low level, the potential of the signal SO rises again. A potential difference DV22 (shown in the figure) exists between the output terminal SO_OUT that outputs SO and the node N21. (not occurring) occurs.

[0112] The potential difference DV22 is between one terminal of the capacitance element C21 and the other terminal of the capacitance element C21. When the signal SO changes from low to high, the capacitance element C2 The potential of node N21 can be made higher than the high power supply potential VDD by the capacitive coupling of 1. Cut.

[0113] When the potential of the node N21 becomes higher than the high power supply potential VDD, the potential of the signal SO is set to the high power supply potential VDD. In addition, the voltage of the node N21 that is higher than the high power supply potential VDD can be The signal level can be increased by using a transistor with low off-state current, which will be described later, as the transistor 23. Even if the period during which signal SI is at low level (period during which signal SIB is at high level) is long, It is possible.

[0114] In the period D23, the signal SI changes from a low level to a high level, and the signal SIB changes to a high level. The period when the signal SI changes from high to low, and the period when the signal SIB changes from high to low, This is the period of the rule.

[0115] During a period D23, the node N21 changes from a high level to a low level, and the transistor Node N22 changes from a conductive state to a non-conductive state. bell, causing transistor 25 to change from a non-conducting state to a conducting state.

[0116] When the transistor 25 changes to a conductive state, the signal SOB goes high. Even if the transistor 22 changes to a non-conductive state, the signal SO does not immediately go low. After signal SOB goes high, transistor 21 changes to a conductive state and signal SO goes low. When the signal SO goes low, the transistor 24 goes into a non-conductive state. This becomes:

[0117] Here, even if the signal SOB becomes high level, the transistor does not operate until the signal SO becomes low level. Therefore, the potential of the signal SOB is higher than the high power supply potential VDD. After the transistor 24 is turned off, the potential of the signal SOB rises again. Rise.

[0118] On the other hand, after the node N22 changes from low level to high level, the signal SOB goes high. After the signal SO changes to low level, the potential of the signal SOB rises again. A potential difference DV23 exists between the output terminal SOB_OUT that outputs the signal SOB and the node N22. (not shown) occurs.

[0119] The potential difference DV23 is between one terminal of the capacitance element C22 and the other terminal of the capacitance element C22. When the signal SOB changes from low to high, the capacitance element C The potential of the node N22 can be made higher than the high power supply potential VDD by the capacitive coupling of the node N22. can.

[0120] When the potential of the node N22 becomes higher than the high power supply potential VDD, the potential of the signal SOB becomes higher than the high power supply potential VDD. The potential of the node N22, which is higher than the high power supply potential VDD, can be set to the potential VDD. The potential is set to a value that is lower than the value that is lowered by using a transistor with low off-state current, which will be described later, as the transistor 26. The period during which the signal SI is at a high level (the period during which the signal SIB is at a low level) is maintained even if it is long. It is possible.

[0121] In a period D24, the signal SI changes from a high level to a low level, and the signal SIB changes from a low level to a low level. The period when the signal SI changes from low to high level, and the period when the signal SIB changes from low to high level It should be noted that the period D24 is the same as the period D22, and therefore the explanation thereof will be omitted.

[0122] As described above, the semiconductor device 20 is a logic circuit configured using n-channel transistors. A potential difference DV22 occurs between the output terminal SO_OUT and the node N21. Therefore, the potential of the node N21 is more reliably controlled than in the examples disclosed in Patent Document 1 or Patent Document 2. The output terminal SOB_OUT and the A potential difference DV23 occurs between the gate N22 and the gate N23. The potential of the node N22 can be made higher than the high power supply potential VDD more reliably than in the example shown in FIG. can.

[0123] When the signal SO output from the output terminal SO_OUT is at a high level, the voltage of the node N21 is By setting the potential higher than the high power supply potential VDD, the output terminal S When the signal SOB output from OB_OUT is at a high level, it raises the potential of the node N22. By making it higher than the power supply potential VDD, it rises to the high power supply potential VDD. When the signal SOB is at a low level, it drops to the low power supply potential VSS, and the semiconductor device 20 After the high or low level of the signals SO and SOB is determined, It has the feature that no through current flows from the power supply potential VDD to the low power supply potential VSS.

[0124] <Transistors that make up semiconductor devices> Transistors 11 to 18 that constitute the semiconductor device 10, and The transistors 21 to 26 constituting the transistor 20 have a metal oxide film in the channel forming region. A transistor having an oxide (OS transistor) can be used.

[0125] OS transistors have a very small off-state current and are ideal for applications where a high voltage is applied between the source and drain. The transistor has the following characteristics: it can be applied to a semiconductor device; it is a thin film transistor and can be provided in a stacked structure; Here, the off-state current is the drain current when the transistor is in the off state. Since the band gap of the oxide semiconductor is 2.5 eV or more, preferably 3.0 eV or more, Therefore, OS transistors have the characteristics of low leakage current due to thermal excitation and extremely low off-state current. The OS transistor has, for example, an off-state current of 100 Ω / μm per channel width. A / μm or less, or 10zA / μm or less, or 1zA / μm or less, or 10yA / It can be made to be μm or less.

[0126] In particular, transistor 13, transistor 14, transistor 17, transistor 18, The transistor 23 and the transistor 26 are transistors with small off-state current. As a result, the signal SI is low during the period D12 or the period D22. Even if the period during which the signal SIB is at a high level is long, the high power supply potential VDD The potential of the node N11 or the node N21 that has risen above this level can be maintained for a long time. During the period D13 or the period D23, the signal SI is at a high level (signal SI Even if the period during which the signal B is at a low level is long, the voltage at the node N1 2 or the potential of node N22 can be maintained for a long time.

[0127] In addition, OS transistors are less likely to experience an increase in off-state current even in high-temperature environments. The OS transistor has the advantage of having a large ratio of on-current to off-current. By configuring the device 10 or the semiconductor device 20, the reliability of the semiconductor device can be improved. can.

[0128] The metal oxide used in the channel formation region of an OS transistor is indium (In) and It is preferable that the oxide semiconductor contains at least one of copper (Cu) and zinc (Zn). Examples of suitable oxide semiconductors include In-M-Zn oxide (wherein element M is, for example, Al, Ga, Y, or The most common is Sn. It reduces impurities such as water and hydrogen, which act as electron donors. By reducing the oxygen vacancies, the oxide semiconductor can be made i-type (intrinsic) or substantially i-type. Such an oxide semiconductor is called a highly purified oxide semiconductor. The OS transistor can be described in detail in the third and fourth embodiments. will be explained.

[0129] In addition, since the OS transistor is a thin film transistor, it can be provided as a stacked layer. For example, on a circuit configured using Si transistors formed on a single crystal silicon substrate Therefore, the semiconductor device 10 or the semiconductor The chip area of ​​the device 20 can be reduced.

[0130] Alternatively, the transistors 11 to 18 that constitute the semiconductor device 10, and The transistors 21 to 26 constituting the semiconductor device 20 are OS transistors. For example, a transistor having a large band gap in the channel formation region may be used. A transistor having a semiconductor with a wide band gap may be used. It may refer to semiconductors with a band gap of 2.2 eV or more, such as silicon carbide and nitride semiconductors. Examples include lithium and diamond.

[0131] The transistors 11 to 18 that constitute the semiconductor device 10 and the semiconductor The transistors 21 to 26 constituting the semiconductor device 20 each have a back gate. A transistor may also be used.

[0132] As an example of a transistor having a back gate, FIG. 5A shows a circuit diagram of a transistor 31. The transistor 31 has a gate (also called a front gate), a drain, a source, and a In Figure 5A, the gates are G, G, and G. (gate), D (drain), S (source), and BG (backgate).

[0133] As an example of using the transistor 31, the back gate is electrically connected to the gate, and the back gate The back gate is electrically connected to the source, and a predetermined potential is applied to the back gate. For example, the back gate may be By electrically connecting the gate, the on-current of the transistor 31 can be increased. In addition, by applying a predetermined potential to the back gate, the threshold voltage of the transistor 31 The cross-sectional structure of a transistor having a back gate can be changed. This is explained in form 3.

[0134] The transistors 11 to 18 that constitute the semiconductor device 10 and the semiconductor The transistors 21 to 26 constituting the device 20 are provided with a plurality of gates (multi-gates). A transistor having a gate (also referred to as a gate) may be used.

[0135] As an example of a transistor having multiple gates, FIG. 5B shows a transistor having two gates (double gate , also referred to as ). The transistor 32 has four In FIG. 5B, the gate 1, gate 2, drain, and source terminals are G These are represented as 1 (gate 1), G2 (gate 2), D (drain), and S (source).

[0136] As an example of using the transistor 32, the gate 1 and the gate 2 are electrically connected, or the gate A predetermined potential may be applied to gate 1 or gate 2. For example, gate 1 and gate 2 may be electrically connected to , the off-state current of the transistor 32 can be reduced in some cases. In addition, by applying a predetermined potential to the gate 1 or gate 2, the transistor 32 can be made to withstand voltage. In some cases, it may be possible to use a transistor with a high

[0137] For example, the transistor 11 and the transistor 15 constituting the semiconductor device 10 are An example using a transistor 31 having a gate is shown in FIG. 5C (in FIG. 5C, (shown as transistor 31_1 and transistor 31_2). The back gate of the transistor 31 is electrically connected to the gate of the transistor 31 .

[0138] For example, the transistor 11 and the transistor 15 constituting the semiconductor device 10 are An example using a transistor 32 with a gate is shown in FIG. 5D (in FIG. 5D, (shown as transistor 32_1 and transistor 32_2). The gate 1 of the transistor 32 is electrically connected to the gate 2 of the transistor 32 .

[0139] This embodiment may be implemented in appropriate combination with other embodiments described in this specification. It is possible.

[0140] (Embodiment 2) In this embodiment, the semiconductor device 10 described in the above embodiment is applied to a general-purpose logic An example of configuring a circuit will be described. The semiconductor device 10 described in the above embodiment is 、It can be used as a NOT circuit that inverts logic or a buffer circuit that does not invert logic. It can be done.

[0141] The semiconductor device 10 receives the signal SI and the signal SIB and outputs the signal SO and the signal SOB. The signal SIB is a signal with the logic of the signal SI inverted, and the signal SOB is a signal with the logic of the signal SO inverted. Therefore, the output terminal of the semiconductor device 10 can be electrically connected to the input terminal of another semiconductor device 10. Since it is a signal with the logic of the signal SO inverted, the output terminal of the semiconductor device 10 can be electrically connected to the input terminal of another semiconductor device 10. It is possible.

[0142] <NAND circuit> FIG. 6 is a circuit diagram showing a configuration example of the semiconductor device 40. The semiconductor device 40 is a semiconductor device applying the semiconductor device 10 and has a function as a NAND circuit. The semiconductor device 40 has transistors 41 to 50, a capacitor element C41, and a capacitor element C42. The transistors 41 to 50 are n-channel type transistors. The semiconductor device 40 has transistors 41 to 50, a capacitor element C41, and a capacitor element C42. The transistors 41 to 50 are n-channel type transistors.

[0143] The semiconductor device 40 has a wiring VSS_IN to which a low power supply potential VSS is supplied, a wiring VDD_IN to which a high power supply potential VDD is supplied, an input terminal SI1_IN to which a signal SI1 is input, an input terminal SI2_IN to which a signal SI2 is input, an input terminal SI1B_IN to which a signal SI1B is input, an input terminal SI2B_IN to which a signal SI2B is input, an output terminal SO1_OUT that outputs a signal SO1, and an output terminal SO1B_OUT that outputs a signal SO1B. Here, the high power supply potential VDD is a potential higher than the low power supply potential VSS, and the low power supply potential VSS may be a reference potential in the semiconductor device 40. Also, the signal SI1, the signal SI2 The semiconductor device 40 has a wiring VSS_IN to which a low power supply potential VSS is supplied, a wiring VDD_IN to which a high power supply potential VDD is supplied, an input terminal SI1_IN to which a signal SI1 is input, an input terminal SI2_IN to which a signal SI2 is input, an input terminal SI1B_IN to which a signal SI1B is input, an input terminal SI2B_IN to which a signal SI2B is input, an output terminal SO1_OUT that outputs a signal SO1, and an output terminal SO1B_OUT that outputs a signal SO1B. Here, the high power supply potential VDD is a potential higher than the low power supply potential VSS, and the low power supply potential VSS may be a reference potential in the semiconductor device 40. Also, the signal SI1, the signal SI2 Here, the high power supply potential VDD is a potential higher than the low power supply potential VSS, and the low power supply potential VSS may be a reference potential in the semiconductor device 40. Also, the signal SI1, the signal SI2 .

[0144] Here, the high power supply potential VDD is a potential higher than the low power supply potential VSS, and the low power supply potential VSS may be a reference potential in the semiconductor device 40. Also, the signal SI1, the signal SI2 Here, the high power supply potential VDD is a potential higher than the low power supply potential VSS, and the low power supply potential VSS may be a reference potential in the semiconductor device 40. Also, the signal SI1, the signal SI2 , signal SI1B, and signal SI2B are digital signals, and signals SI1, SI2 The potential representing the high level of the signals SI1B and SI2B is the high power supply potential VDD. The potential representing the low level can be the low power supply potential VSS. Signal SI1B is a signal obtained by inverting the logic of signal SI1, and signal SI2B is a signal obtained by inverting the logic of signal SI2. This is a signal with the logic of

[0145] In the semiconductor device 40, one of the source and drain of the transistor 41 is connected to the wiring VS The other of the source and drain of the transistor 41 is electrically connected to the transistor S_IN. One of the source and drain of the transistor 42, one terminal of the capacitance element C41, and and the source or drain of the transistor 42. The other end is electrically connected to the wiring VDD_IN.

[0146] The gate of transistor 41 is connected to the gate of transistor 45, the source of transistor 50, or is one of the drains, one of the source or drain of the transistor 49, One terminal of the transistor 47 is electrically connected to the gate of the transistor 47. The gate of the transistor 42 is connected to the other terminal of the capacitance element C41, the source or drain of the transistor 44, one of the drains of the transistor 43, one of the source or drain of the transistor 45 The source or drain of transistor 50 and the gate of transistor 46 are connected to each other. It is electrically connected to the port.

[0147] The other of the source and the drain of the transistor 45 is electrically connected to the wiring VSS_IN. The other of the source and the drain of the transistor 44 is electrically connected to the wiring VDD_IN. The other of the source and the drain of the transistor 43 is electrically connected to the wiring VDD_IN. The gate of the transistor 44 is electrically connected to the input terminal SI2B_IN. The gate of the transistor 43 is electrically connected to the input terminal SI1B_IN.

[0148] The other of the source and the drain of the transistor 50 is electrically connected to the wiring VSS_IN. The other of the source and drain of the transistor 49 is connected to the source or drain of the transistor 48. is electrically connected to one of the drains of the transistor 48, and the other of the source or drain of the transistor 48. is electrically connected to the wiring VDD_IN, and the gate of the transistor 49 is connected to the input terminal SI The gate of the transistor 48 is electrically connected to the input terminal SI1_IN. electrically connected.

[0149] One of the source and the drain of the transistor 46 is electrically connected to the wiring VSS_IN. The other of the source and drain of the transistor 46 is connected to the source or drain of the transistor 47. is connected to one side of the drain, the other terminal of the capacitance element C42, and the output terminal SO1B_OUT. The other of the source and drain of the transistor 47 is electrically connected to the wiring VDD_I N.

[0150] Here, the gate of transistor 41, the gate of transistor 45, and the gate of transistor 50 One of the source or drain of the transistor 49, one of the source or drain of the capacitor The connection between one terminal of the transistor C42 and the gate of the transistor 47 is connected to a node N42. is referred to as. Also, one of the gates of transistor 42, the other terminal of capacitor element C41, the source or drain of transistor 45, one of the source or drain of transistor 44, one of the source or drain of transistor 43, the gate of transistor 50, and the connection part with the gate of transistor 46 are referred to as node N41. The operation example of semiconductor device 40 will be described later. one of the source or drain of transistor 45, one of the source or drain of transistor 44, one of the source or drain of transistor 43, the gate of transistor 50, and the connection part with the gate of transistor 46 are referred to as node N41. The operation example of semiconductor device 40 will be described later.

[0151] <NOR circuit> FIG. 7 is a circuit diagram showing a configuration example of semiconductor device 60. Semiconductor device 60 is a semiconductor device applying semiconductor device 10 and has a function as a NOR circuit. Semiconductor device 60 includes transistors 61 to 70, capacitor element C61, and capacitor element C62. Transistors 61 to 70 are n-channel type transistors. Semiconductor device 60 is a semiconductor device applying semiconductor device 10 and has a function as a NOR circuit. Semiconductor device 60 includes transistors 61 to 70, capacitor element C61, and capacitor element C62. Transistors 61 to 70 are n-channel type transistors.

[0152] Similar to semiconductor device 40, semiconductor device 60 has a wiring VSS_IN to which a low power supply potential VSS is supplied, a wiring VDD_IN to which a high power supply potential VDD is supplied, an input terminal SI1_IN to which signal SI1 is input, an input terminal SI2_IN to which signal SI2 is input, an input terminal SI1B_IN to which signal SI1B is input, an input terminal SI2B_IN to which signal SI2B is input, an output terminal SO2_OUT for outputting signal SO2, and an output terminal SO2B_OUT for outputting signal SO2B. For the sake of repeated explanation, the description of potential and signal is omitted. Similar to semiconductor device 40, semiconductor device 60 has a wiring VSS_IN to which a low power supply potential VSS is supplied, a wiring VDD_IN to which a high power supply potential VDD is supplied, an input terminal SI1_IN to which signal SI1 is input, an input terminal SI2_IN to which signal SI2 is input, an input terminal SI1B_IN to which signal SI1B is input, an input terminal SI2B_IN to which signal SI2B is input, a signal SO2 is output, and an output terminal SO2_OUT for outputting signal SO2, and an output terminal SO2B_OUT for outputting signal SO2B. For the sake of repeated explanation, the description of potential and signal is omitted. is omitted.

[0153] In semiconductor device 60, one of the source or drain of transistor 61 is electrically connected to wiring VSS_IN, and the other of the source or drain of transistor 61 is the same as wiring VSS_IN, and the other of the source or drain of transistor 61 is the same as One of the source and drain of the transistor 62, one terminal of the capacitance element C61, and and the source or drain of the transistor 62. The other end is electrically connected to the wiring VDD_IN.

[0154] The gate of transistor 61 is connected to the gate of transistor 65, the source of transistor 70, and one of the source and drain of transistor 68; one of the source and drain of transistor 6 One of the source or drain of the capacitor C62, and the transistor The gate of the transistor 62 is electrically connected to the gate of the capacitor C6 the other terminal of transistor 1, one of the source or drain of transistor 64, The source or drain of the transistor 70 and the gate of the transistor 66 It is electrically connected to the gate.

[0155] The other of the source and the drain of the transistor 65 is electrically connected to the wiring VSS_IN. The other of the source or drain of the transistor 64 is connected to the source or drain of the transistor 63. is electrically connected to one of the drains of the transistor 63, and the other of the source or drain of the transistor 63. is electrically connected to the wiring VDD_IN, and the gate of the transistor 64 is connected to the input terminal SI 2B_IN, and the gate of the transistor 63 is electrically connected to the input terminal SI1B_IN and electrically connected to each other.

[0156] The other of the source and the drain of the transistor 70 is electrically connected to the wiring VSS_IN. The other of the source and the drain of the transistor 68 is electrically connected to the wiring VDD_IN. The other of the source and drain of the transistor 69 is electrically connected to the wiring VDD_IN. The gate of the transistor 68 is electrically connected to the input terminal SI1_IN. The gate of the transistor 69 is electrically connected to the input terminal SI2_IN.

[0157] One of the source and the drain of the transistor 66 is electrically connected to the wiring VSS_IN. The other of the source or drain of the transistor 66 is connected to the source or drain of the transistor 67. is connected to one side of the drain, the other terminal of the capacitance element C62, and the output terminal SO2B_OUT. The other of the source and drain of the transistor 67 is electrically connected to the wiring VDD_I N.

[0158] Here, the gate of transistor 61, the gate of transistor 65, and the gate of transistor 70 One of the source or drain of transistor 68, one of the source or drain of transistor One of the source or drain of the transistor 69, one terminal of the capacitance element C62, and The connection point between the gate of the transistor 67 and the node N62 is called a node N62. The gate of the capacitor C61, the other terminal of the capacitor C61, and the source or drain of the transistor 64 On the other hand, one of the source or drain of transistor 65, the gate of transistor 70, and The connection point with the gate of transistor 66 is called node N61.

[0159] <Example of semiconductor device operation> FIG. 8 is a timing chart showing an example of the operation of the semiconductor device 40 and the semiconductor device 60. FIG. 8 shows the signals SI1, SI2, SO1, SO1B, SO2, and The potential of the signal SO2B is shown divided into periods D41 to D45.

[0160] [Period D41] A period D41 is a period during which the signals SI1 and SI2 change from a high level to a low level. Also, the signal SI1B is a period in which the signals SI1 and SI2 are at a low level. The signal SI2B is a signal obtained by inverting the logic of the signal SI2. Since it is a signal, the explanation will be omitted (not shown).

[0161] In the semiconductor device 40 during the period D41, the transistors 48 and 49 are conductive. The transistor 43 and the transistor 44 are in the non-conducting state. The transistors 43 and 44 change from the ON state to the ON state. On the other hand, the transistors 48 and 49 are turned on. Even if node N9 changes to a non-conductive state, node N42 does not immediately go low. After node N41 goes high, transistor 50 turns on and node N42 goes low. -level.

[0162] When node N41 goes high, transistor 50, transistor 46, and transistor When the node N42 goes low, the transistor 42 is turned on. Transistor 45, transistor 41, and transistor 47 are non-conductive. Since transistor 42 is conductive and transistor 41 is non-conductive, the signal SO1 is at a high level. Also, transistor 47 is in a non-conductive state. Since the resistor 46 is conductive, the signal SO1B goes low.

[0163] Here, even if the node N41 becomes high level and the transistor 42 becomes conductive, Since the transistor 41 is in a conducting state until the node N42 goes low, the signal S O1 goes high with a delay from the timing when node N41 goes high. Therefore, a potential difference occurs between the output terminal SO1_OUT and the node N41, and the potential difference is , is also applied between one terminal of the capacitance element C41 and the other terminal of the capacitance element C41.

[0164] A potential difference is applied between one terminal of the capacitance element C41 and the other terminal of the capacitance element C41. In this state, when the signal SO1 changes from low level to high level, the capacitance of the capacitance element C41 Due to capacitance coupling, the potential of the node N41 rises, and the potential of the node N41 becomes higher than the high power supply potential VDD. When the potential of the node N41 becomes higher than the high power supply potential VDD, The potential of the signal SO1 can be set to the high power supply potential VDD. The increased potential of the node N41 is supplied to the transistors 43, 44 and 45. By using the transistor with a small off-state current as the transistor 45, the signal SO1 can be This means that the signal SO1B can be maintained at a low level even if the period during which it is at a low level is long. Cut.

[0165] In the semiconductor device 60 during the period D41, the transistors 68 and 69 are conductive. The transistor 63 and the transistor 64 are in the non-conducting state. The transistors 63 and 64 change from the ON state to the ON state. On the other hand, the transistors 68 and 6 Even if node N9 changes to a non-conductive state, node N62 does not immediately go low. After 61 goes high, transistor 70 changes to a conductive state and node N62 goes low. -level.

[0166] When node N61 goes high, transistors 70, 66, and When the node N62 goes low, the transistor 62 goes into a conductive state. Transistor 65, transistor 61, and transistor 67 are non-conductive. Since transistor 62 is conductive and transistor 61 is non-conductive, the signal SO2 is at a high level. Also, transistor 67 is in a non-conductive state. Since the resistor 66 is conductive, the signal SO2B goes low.

[0167] Here, even if the node N61 becomes high level and the transistor 62 becomes conductive, Since the transistor 61 is in a conducting state until the node N62 goes low, the signal S O2 goes high with a delay from the timing when node N61 goes high. Therefore, a potential difference occurs between the output terminal SO2_OUT and the node N61, and the potential difference is , is also applied between one terminal of the capacitance element C61 and the other terminal of the capacitance element C61.

[0168] A potential difference is applied between one terminal of the capacitance element C61 and the other terminal of the capacitance element C61. In this state, when the signal SO2 changes from low level to high level, the capacitance of the capacitive element C61 Due to capacitance coupling, the potential of the node N61 rises, and the potential of the node N61 becomes higher than the high power supply potential VDD. When the potential of the node N61 becomes higher than the high power supply potential VDD, The potential of the signal SO2 can be set to the high power supply potential VDD. The increased potential of the node N61 is applied to the transistors 63, 64 and 65. By using the transistor with a small off-state current as described above for the transistor 65, the signal SO2 This means that the period during which the signal is at a low level (the period during which the signal SO2B is at a low level) can be maintained even if it is long. Cut.

[0169] [Period D42] The period D42 is the period during which the signal SI1 changes from a low level to a high level, and the period during which the signal S This is the period when I1 is at a high level and signal SI2 is at a low level.

[0170] In the semiconductor device 40 during the period D42, the transistor 48 changes from a non-conductive state to a conductive state. The transistor 43 changes from a conducting state to a non-conducting state. In the conductive state, transistor 44 remains in the conductive state. Therefore, node N41 remains high. level, node N42 remains at low level.

[0171] Since node N41 is at a high level, transistor 50, transistor 46, and The transistor 42 is in a conductive state. Also, since the node N42 is at a low level, the transistor Transistor 45, transistor 41, and transistor 47 are in a non-conductive state. Since transistor 42 is conductive and transistor 41 is non-conductive, signal SO1 is The transistor 47 is in a non-conductive state, and the transistor 46 is in a conductive state. Since the signal SO1B is in the ON state, the signal SO1B remains at a low level. The semiconductor device 40 in this state maintains the state of the period D41.

[0172] In the semiconductor device 60 during the period D42, the transistor 69 is in a non-conductive state, and the transistor 64 does not change from a conducting state, but transistor 68 changes from a non-conducting state to a conducting state. , transistor 63 changes from a conducting state to a non-conducting state. When the voltage of the transistor 63 changes to 0, the node N62 goes high. Even if the node N62 changes to a high level, the node N61 does not immediately go to a low level. After this, transistor 65 changes to a conductive state, and node N61 goes low. .

[0173] When node N61 goes low, transistor 70, transistor 66, and transistor When the node N62 goes high, the transistor 62 goes into a non-conductive state. Transistor 65, transistor 61, and transistor 67 are in a conducting state. Since transistor 62 is non-conductive and transistor 61 is conductive, the signal SO2 is at a low level. Also, transistor 67 is in a conducting state and transistor Since the starter 66 is non-conductive, the signal SO2B goes high.

[0174] Here, even if the node N62 becomes high level and the transistor 67 becomes conductive, Since the transistor 66 is in a conducting state until the node N61 goes low, the signal S O2B goes high with a delay from the timing when node N62 goes high. Therefore, a potential difference occurs between the output terminal SO2B_OUT and the node N62, and the potential The difference is also applied between one terminal of the capacitance element C62 and the other terminal of the capacitance element C62. do.

[0175] A potential difference is applied between one terminal of the capacitance element C62 and the other terminal of the capacitance element C62. In this state, when the signal SO2B changes from low level to high level, the capacitance element C62 Due to capacitive coupling, the potential of the node N62 rises, and the potential of the node N62 rises to the high power supply potential VDD When the potential of the node N62 becomes higher than the high power supply potential VDD, The potential of the signal SO2B can be set to the high power supply potential VDD. The higher potential of node N62 is supplied to transistors 68, 69 and 69a. By using the transistor with a small off-state current as the transistor 70, the signal SO2B is maintained even if the period during which the signal is at a high level (the period during which the signal SO2 is at a low level) is long. can be done.

[0176] [Period D43] In the period D43, the signal SI1 changes from a high level to a low level, and the signal SI2 changes from a low level to a The period when the signal SI1 changes from low to high level, and the period when the signal SI2 changes from low to high level This is the level period.

[0177] In the semiconductor device 40 during the period D43, the transistors 48 and 44 are conductive. The transistor 49 and the transistor 43 are in the non-conducting state. Therefore, the node N41 is at a high level and the node N42 is at a low level. It remains a bell.

[0178] Since node N41 is at a high level, transistor 50, transistor 46, and The transistor 42 is in a conductive state. Also, since the node N42 is at a low level, the transistor Transistor 45, transistor 41, and transistor 47 are in a non-conductive state. Since transistor 42 is conductive and transistor 41 is non-conductive, signal SO1 is The transistor 47 is in a non-conductive state, and the transistor 46 is in a conductive state. Since the signal SO1B is in the ON state, the signal SO1B remains at a low level. The semiconductor device 40 in this state maintains the state of the period D42.

[0179] In the semiconductor device 60 during the period D43, the transistors 68 and 64 are conductive. The transistor 69 and the transistor 63 are in the non-conducting state. Therefore, the node N61 is at a low level and the node N62 is at a high level. It remains a bell.

[0180] Since node N61 is at a low level, transistor 70, transistor 66, and The transistor 62 is in a non-conductive state. Also, since the node N62 is at a high level, the transistor Transistor 65, transistor 61, and transistor 67 are in a conducting state. Since transistor 62 is non-conductive and transistor 61 is conductive, signal SO2 is The transistor 67 is in a conducting state, and the transistor 66 is in a non-conducting state. Since the signal SO2B is in the ON state, the signal SO2B remains at a high level. The semiconductor device 60 in this state maintains the state of the period D42.

[0181] [Period D44] The period D44 is the period during which the signal SI1 changes from a low level to a high level, and the period during which the signal S I1, signal SI2 is at a high level.

[0182] In the semiconductor device 40 during the period D44, the transistor 49 is in a conducting state, and the transistor 4 4 does not change from a non-conducting state, but transistor 48 changes from a non-conducting state to a conducting state. When transistor 43 changes from a conducting state to a non-conducting state, transistor 48 changes from a conducting state to a non-conducting state. When the transistor 43 is in a non-conductive state, the node N42 goes high. Even if the node N42 changes to a high level, the node N41 does not immediately go to a low level. After this, transistor 45 changes to a conductive state, and node N41 goes low. .

[0183] When node N41 goes low, transistor 50, transistor 46, and transistor When the node N42 goes high, the transistor 42 goes into a non-conductive state. Transistor 45, transistor 41, and transistor 47 are in a conducting state. Since transistor 42 is non-conductive and transistor 41 is conductive, the signal SO1 is at a low level. Also, transistor 47 is in a conducting state and transistor Since the starter 46 is non-conductive, the signal SO1B goes high.

[0184] Here, even if the node N42 becomes high level and the transistor 47 becomes conductive, Since the transistor 46 is in a conducting state until the node N41 goes low, the signal S O1B goes high with a delay from the timing when node N42 goes high. Therefore, a potential difference occurs between the output terminal SO1B_OUT and the node N42, and the potential The difference is also applied between one terminal of the capacitance element C42 and the other terminal of the capacitance element C42. do.

[0185] A potential difference is applied between one terminal of the capacitance element C42 and the other terminal of the capacitance element C42. In this state, when the signal SO1B changes from low level to high level, the capacitance element C42 Due to capacitive coupling, the potential of node N42 rises, and the potential of node N42 rises to the high power supply potential VDD When the potential of the node N42 becomes higher than the high power supply potential VDD, The potential of the signal SO1B can be set to the high power supply potential VDD. The higher potential of node N42 is applied to transistors 48, 49 and 50. By using the transistor with a small off-state current as the transistor 50, the signal SO1B is maintained even if the period during which the signal is at a high level (the period during which the signal SO1 is at a low level) is long. can be done.

[0186] In the semiconductor device 60 during the period D44, the transistor 68 changes from a non-conductive state to a conductive state. The transistor 63 changes from a conducting state to a non-conducting state. In the conductive state, transistor 69 remains in the conductive state. Therefore, node N61 is low. level, node N62 remains at high level.

[0187] Since node N61 is at a low level, transistor 70, transistor 66, and The transistor 62 is in a non-conductive state. Also, since the node N62 is at a high level, the transistor Transistor 65, transistor 61, and transistor 67 are in a conducting state. Since transistor 62 is non-conductive and transistor 61 is conductive, signal SO2 is The transistor 67 is in a conducting state, and the transistor 66 is in a non-conducting state. Since the signal SO2B is in the ON state, the signal SO2B remains at a high level. The semiconductor device 60 in this state maintains the state of the period D43.

[0188] [Period D45] A period D45 is a period during which the signals SI1 and SI2 change from a high level to a low level. The period D45 is a period in which the signals SI1 and SI2 are at a low level. 41, so the explanation will be omitted.

[0189] As described above, the semiconductor device 40 receives the signals SI1, SI2, SI1B, and SI 2B is input, and the semiconductor device 40 outputs the signal SO1 and the signal SO1B. That is, the semiconductor device 40 has a function as a NAND circuit. , signals SI1, SI2, SI1B, and SI2B are input, and the semiconductor device 60 , signal SO2 and signal SO2B. That is, the semiconductor device 60 is a NOR circuit It has the function as.

[0190] The signal SO1B is a signal obtained by inverting the logic of the signal SO1, and the signal SO2B is a signal obtained by inverting the logic of the signal SO2. Because the logic is inverted, it functions as a NOT circuit or a buffer circuit. The semiconductor device 10, the semiconductor device 40 having the function of a NAND circuit, and the semiconductor device 40 having the function of a NOR circuit The semiconductor devices 60 functioning as a circuit can be electrically connected to each other. That is, by using the semiconductor device 10, the semiconductor device 40, and the semiconductor device 60, it is possible to It is possible to construct a logic circuit.

[0191] This embodiment may be implemented in appropriate combination with other embodiments described in this specification. It is possible.

[0192] (Embodiment 3) In this embodiment, the transistor constituting the semiconductor device 10 described in the above embodiment is , the transistors constituting the semiconductor device 20, the transistors constituting the semiconductor device 40, and Also, an OS transistor that can be used as a transistor constituting the semiconductor device 60 The OS transistor is a thin film transistor, and a stacked structure will be described. Therefore, in this embodiment, a Si transistor formed on a single crystal silicon substrate is used. A configuration example of a semiconductor device in which an OS transistor is provided above a transistor will be described.

[0193] <Configuration example of semiconductor device> The semiconductor device shown in FIG. 9 includes a transistor 300, a transistor 500, and a capacitor element 10A is a cross-sectional view of the transistor 500 in the channel length direction. FIG. 10B is a cross-sectional view of the transistor 500 in the channel width direction, and FIG. 10C is a cross-sectional view of the transistor 500 in the channel width direction. FIG. 3 is a cross-sectional view of the capacitor 300 in the channel width direction.

[0194] The transistor 500 is a transistor having a metal oxide in a channel formation region (OS transistor). The transistor 500 is a transistor that can apply a high voltage between the source and drain. The off-current is unlikely to increase even in high-temperature environments, and the ratio of on-current to off-current is In the above embodiment, this is referred to as the semiconductor device 10, the semiconductor By using the semiconductor device 20, the semiconductor device 40, and the semiconductor device 60, Therefore, the device can be a highly reliable semiconductor device.

[0195] The semiconductor device described in this embodiment includes, as shown in FIG. 9, a transistor 300, a transistor The transistor 500 has a transistor 30 and a capacitor 600. 0, and the capacitance element 600 is provided above the transistor 300 and the transistor 500 It is located above.

[0196] The transistor 300 is disposed on a substrate 311, and includes a conductor 316, an insulator 315, and a substrate 316. 11, and functions as a source region or a drain region. The low resistance region 314a and the low resistance region 314b are connected to each other.

[0197] The transistor 300 is formed by forming a top surface of the semiconductor region 313 and a channel region 314 as shown in FIG. 10C. The side surfaces in the width direction are covered with the conductor 316 via the insulator 315. By making the resistor 300 a fin type, the effective channel width is increased, and This can improve the on-characteristics of the transistor 300. In addition, the contribution of the electric field of the gate electrode can be increased, thereby improving the off-state characteristics of the transistor 300. .

[0198] The transistor 300 may be either a p-channel type or an n-channel type.

[0199] The region where the channel of the semiconductor region 313 is formed, the region nearby, the source region, or the drain region In the low resistance region 314a and the low resistance region 314b, which are the drain region, silicon is It preferably contains a semiconductor such as a silicon-based semiconductor, and preferably contains single crystal silicon. Or Ge (germanium), SiGe (silicon germanium), GaAs (gallium It may be formed of a material containing gallium aluminum arsenide (GaAlAs), GaAlAs (Gallium Aluminum Arsenide), etc. By applying stress to the crystal lattice and changing the lattice spacing, we can control the effective mass of silicon. Alternatively, GaAs and GaAlAs may be used to form a transistor. The 300 is a HEMT (High Electron Mobility Transistor) tor) can also be used.

[0200] The low resistance region 314a and the low resistance region 314b are semiconductor regions applied to the semiconductor region 313. In addition to the body material, elements that impart n-type conductivity, such as arsenic or phosphorus, or p-type conductivity, such as boron, are added. The element imparting electrical conductivity is included.

[0201] The conductor 316 that functions as the gate electrode is made of an element that gives n-type conductivity, such as arsenic or phosphorus. Semiconductor materials such as silicon that contain elements that impart p-type conductivity, such as silicon or boron A conductive material such as a metal material, an alloy material, or a metal oxide material can be used.

[0202] Since the work function is determined by the conductor material, the work function can be changed by changing the conductor material. The Vth of the transistor can be adjusted. It is preferable to use a material such as tantalum. It is preferable to use a metal material such as tungsten or aluminum laminated on the conductor. In particular, tungsten is preferably used in terms of heat resistance.

[0203] The transistor 300 shown in FIG. 9 is an example, and the present invention is not limited to this structure. An appropriate transistor may be used depending on the driving method.

[0204] Over the transistor 300 are insulators 320, 322, 324, and The bodies 326 are stacked one on top of the other.

[0205] The insulators 320, 322, 324, and 326 may be, for example, oxide. Silicon, silicon oxynitride, silicon nitride oxide, silicon nitride, aluminum oxide, oxide Aluminum oxynitride, aluminum nitride oxide, aluminum nitride, etc. may be used.

[0206] The insulator 322 smooths out the steps caused by the transistor 300 and other components disposed below it. For example, the top surface of the insulator 322 may have a function as a planarizing film. Chemical mechanical polishing (CMP) is used to improve the flatness. The surface may be planarized by a planarization process using a polishing method or the like.

[0207] The insulator 324 is also provided with a substrate 311 or a transistor 300 or the like. A film having a barrier property that prevents hydrogen and impurities from diffusing is used in the area where the capacitor 500 is provided. It is preferable that

[0208] An example of a film having a barrier property against hydrogen is silicon nitride formed by a CVD method. Here, a semiconductor having an oxide semiconductor such as the transistor 500 can be used. When hydrogen diffuses into the element, the characteristics of the semiconductor element may be deteriorated. A film that suppresses hydrogen diffusion is used between the transistor 500 and the transistor 300. Specifically, the film that suppresses hydrogen diffusion is a film that has a small amount of hydrogen desorption. The membrane.

[0209] The amount of desorption of hydrogen can be measured, for example, by thermal desorption spectroscopy (TDS). For example, the analysis can be performed using methods such as ion spectroscopy. The amount of hydrogen desorption from the insulator 324 was measured by TDS analysis when the surface temperature of the film was 50°C to 50°C. In the range of 0°C, the amount of desorption converted into hydrogen atoms is converted into the area of ​​the insulator 324. So, 10 x 10 15 atoms / cm 2 Less than or equal to 5 x 10 15 atoms / cm 2 The following is fine.

[0210] It is preferable that the insulator 326 has a lower dielectric constant than the insulator 324. For example, The dielectric constant of the insulator 326 is preferably less than 4, more preferably less than 3. The relative dielectric constant of the insulating material 26 is preferably 0.7 times or less than the relative dielectric constant of the insulating material 324, and more preferably 0.6 times or less. It is more preferable to use a material with a low relative dielectric constant as the interlayer film, thereby reducing the parasitic capacitance generated between wirings. It can be reduced.

[0211] In addition, the insulators 320, 322, 324, and 326 are connected to the capacitance element 6. 00, or the conductor 328 and the conductor 330 connected to the transistor 500 are filled in. The conductors 328 and 330 are plugs or wiring. In addition, the conductor having the function of a plug or wiring may have a plurality of structures. In addition, in this specification and the like, a wiring and a wiring-connected The conductive material may be an integral part of the plug that connects to the conductive material. In some cases, a part of the conductor functions as a plug.

[0212] The materials for each plug and wiring (conductor 328, conductor 330, etc.) are metal materials. Conductive materials such as metals, alloys, metal nitrides, or metal oxides are deposited as single layers or They can be used in layers. Materials such as tungsten and molybdenum, which have both heat resistance and conductivity, are It is preferable to use a high melting point material such as tungsten. It is preferable to form the conductive layer from a low-resistance conductive material such as aluminum or copper. By using this, the wiring resistance can be reduced.

[0213] A wiring layer may be provided on the insulator 326 and the conductor 330. For example, in FIG. An insulator 350, an insulator 352, and an insulator 354 are stacked in this order. In addition, a conductor 356 is formed on the insulators 350, 352, and 354. The conductor 356 functions as a plug or wiring that connects to the transistor 300. The conductor 356 is made of the same material as the conductors 328 and 330. It can be established as follows.

[0214] For example, the insulator 350 has a barrier property against hydrogen, similar to the insulator 324. It is preferable to use an insulator. In addition, the conductor 356 has a barrier property against hydrogen. It is preferable that the insulating material 350 contains a conductor. In particular, the insulating material 350 has a barrier property against hydrogen. A conductor having a barrier property against hydrogen is formed in the opening. The transistor 300 and the transistor 500 can be separated by a barrier layer. Therefore, the diffusion of hydrogen from the resistor 300 to the transistor 500 can be suppressed.

[0215] As a conductor having a barrier property against hydrogen, for example, tantalum nitride or the like is used. In addition, by laminating tantalum nitride and highly conductive tungsten, The diffusion of hydrogen from the transistor 300 can be suppressed while maintaining the conductivity of the transistor 300. In this case, the tantalum nitride layer having a barrier property against hydrogen has a barrier property against hydrogen. It is preferable that the insulating material 350 is in contact with the insulating material 350.

[0216] A wiring layer may be provided on the insulator 354 and the conductor 356. For example, in FIG. An insulator 360, an insulator 362, and an insulator 364 are stacked in this order. In addition, a conductor 366 is formed on the insulators 360, 362, and 364. The conductor 366 functions as a plug or wiring. The conductors 328 and 330 can be formed using the same materials.

[0217] For example, the insulator 360 has a barrier property against hydrogen, similar to the insulator 324. It is preferable to use an insulator. The conductor 366 has a barrier property against hydrogen. It is preferable that the insulating material 360 contains a conductor. In particular, the insulating material 360 has a barrier property against hydrogen. A conductor having a barrier property against hydrogen is formed in the opening. The transistor 300 and the transistor 500 can be separated by a barrier layer. Therefore, the diffusion of hydrogen from the resistor 300 to the transistor 500 can be suppressed.

[0218] A wiring layer may be provided on the insulator 364 and the conductor 366. For example, in FIG. An insulator 370, an insulator 372, and an insulator 374 are stacked in this order. In addition, a conductor 376 is formed on the insulators 370, 372, and 374. The conductor 376 functions as a plug or wiring. The conductors 328 and 330 can be formed using the same materials.

[0219] For example, the insulator 370 has a barrier property against hydrogen, similar to the insulator 324. It is preferable to use an insulator. In addition, the conductor 376 has a barrier property against hydrogen. It is preferable that the insulating material 370 contains a conductor. In particular, the insulating material 370 has a barrier property against hydrogen. A conductor having a barrier property against hydrogen is formed in the opening. The transistor 300 and the transistor 500 can be separated by a barrier layer. Therefore, the diffusion of hydrogen from the resistor 300 to the transistor 500 can be suppressed.

[0220] A wiring layer may be provided on the insulator 374 and the conductor 376. For example, in FIG. An insulator 380, an insulator 382, ​​and an insulator 384 are stacked in this order. In addition, a conductor 386 is formed on the insulators 380, 382, ​​and 384. The conductor 386 functions as a plug or wiring. The conductors 328 and 330 can be formed using the same materials.

[0221] For example, the insulator 380 has a barrier property against hydrogen, similar to the insulator 324. It is preferable to use an insulator. The conductor 386 has a barrier property against hydrogen. It is preferable that the insulating material 380 has a barrier property against hydrogen. A conductor having a barrier property against hydrogen is formed in the opening. The transistor 300 and the transistor 500 can be separated by a barrier layer. Therefore, the diffusion of hydrogen from the resistor 300 to the transistor 500 can be suppressed.

[0222] In the above, the wiring layer including the conductor 356, the wiring layer including the conductor 366, and the conductor 376 The wiring layer including the conductor 386 has been described above. The semiconductor device is not limited to this. Alternatively, the number of wiring layers may be three or less, or five or more wiring layers similar to the wiring layer including the conductor 356 may be provided. Good too.

[0223] On the insulator 384, an insulator 510, an insulator 512, an insulator 514, and an insulator 516 are formed. , and are stacked in this order. It is preferable that either of the insulating layers 516 is made of a material that has a barrier property against oxygen or hydrogen. stomach.

[0224] For example, the insulator 510 and the insulator 514 may include the substrate 311 or the transistor 30. 0 to the region where the transistor 500 is provided. Therefore, it is preferable to use a film having such a barrier property as the insulator 324. The following materials can be used.

[0225] As an example of a film with barrier properties against hydrogen, silicon nitride formed by CVD is used. Here, a semiconductor element including an oxide semiconductor such as the transistor 500 can be The diffusion of hydrogen may deteriorate the characteristics of the semiconductor device. A film that suppresses hydrogen diffusion is used between the transistor 500 and the transistor 300. Specifically, the film that suppresses hydrogen diffusion is a film that desorbs a small amount of hydrogen. .

[0226] In addition, as a film having a barrier property against hydrogen, for example, an insulator 510 and an insulator 5 14 uses metal oxides such as aluminum oxide, hafnium oxide, and tantalum oxide. It is preferable.

[0227] In particular, aluminum oxide is a material that can absorb oxygen and hydrogen, which can cause fluctuations in the electrical characteristics of transistors. Therefore, it has a high blocking effect that prevents impurities such as acid and moisture from passing through the membrane. Aluminum oxide is resistant to hydrogen, moisture, etc. during and after the transistor manufacturing process. It is possible to prevent impurities from being mixed into the transistor 500. This can suppress the release of oxygen from the oxide that makes up the transistor. Suitable for use as a protective film against 500.

[0228] For example, the insulators 512 and 516 may be made of the same material as the insulator 320. In addition, by using a material with a relatively low dielectric constant as the interlayer film, the For example, the insulators 512 and 516 can be formed by using a A silicon oxide film, a silicon oxynitride film, or the like can be used.

[0229] In addition, the insulators 510, 512, 514, and 516 are provided with conductors 5 18, and the conductor that constitutes the transistor 500 (conductor 503 (see FIG. 10A)). The conductor 518 is embedded in the capacitor 600 or the transistor 3. 00 or functions as a wiring. 8 and the conductor 330 can be formed using the same material.

[0230] In particular, the insulator 510 and the conductor 518 in the area in contact with the insulator 514 are free of oxygen, hydrogen, It is preferable that the conductive material has a barrier property against water. The transistor 300 and the transistor 500 have a barrier property against oxygen, hydrogen, and water. The layer separating the transistors 300 and 500 allows for the separation of hydrogen. Diffusion can be suppressed.

[0231] Above the insulator 516 is the transistor 500 .

[0232] As shown in FIGS. 10A and 10B, transistor 500 includes an insulator 514 and an insulator A conductor 503 disposed so as to be embedded in an insulator 516, and a conductor 503 an insulator 520 disposed on the insulator 520; an insulator 522 disposed on the insulator 520; An insulator 524 is disposed on the body 522, and an oxide 530 is disposed on the insulator 524. a, an oxide 530b disposed on the oxide 530a, and an oxide 530b disposed on the oxide 530b. Conductor 542a and conductor 542b are spaced apart, and conductor 542a and conductor The conductive material 542a is disposed on the conductive material 542b, and an opening is formed between the conductive material 542a and the conductive material 542b so as to overlap the conductive material 542a. The insulating material 580 is disposed in the opening, the conductor 560 is disposed in the opening, and the oxide 530b, the conductor 5 42a, conductor 542b, and an insulator 580 disposed between the conductor 560. The insulating layer 550, the oxide 530b, the conductor 542a, the conductor 542b, and the insulator 580 and an insulator 550 and an oxide 530c disposed therebetween.

[0233] 10A and 10B, the oxide 530a, the oxide 530b, the conductor 542a, and an insulator 544 is disposed between the conductor 542b and the insulator 580. In addition, the conductor 560 is preferably a conductor 560a provided inside the insulator 550. and a conductor 560b provided so as to be embedded inside the conductor 560a. It is also preferable to form an insulator 580 on the insulator 580, the conductor 560, and the insulator 550. 74 is preferably placed.

[0234] In the following, the oxide 530a, the oxide 530b, and the oxide 530c will be collectively referred to as oxides 530a, 530b, and 530c. The conductor 542a and the conductor 542b are sometimes referred to as oxide 530. This may be referred to as conductor 542.

[0235] In the transistor 500, the region where the channel is formed and the vicinity thereof are oxidized. 5 shows a structure in which three layers of an oxide 530a, an oxide 530b, and an oxide 530c are stacked. However, the present invention is not limited to this. For example, a single layer of oxide 530b, an oxide a two-layer structure of oxide 530b and oxide 530a; a two-layer structure of oxide 530b and oxide 530c; Alternatively, a stacked structure of four or more layers may be provided. Although the conductor 560 is shown as a two-layer laminate structure, 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. Also, the transistor 500 shown in FIGS. 9, 10A, and 10B is an example. However, the structure is not limited to this, and an appropriate transistor may be used depending on the circuit configuration and driving method. stomach.

[0236] Here, the conductor 560 functions as the gate electrode of the transistor, and the conductors 542a and The conductor 542b functions as a source electrode and a drain electrode, respectively. As shown, the conductor 560 is inserted through the opening in the insulator 580 and the conductors 542a and 542b. The conductor 560, the conductor 542a, and the conductor 542b are formed so as to be embedded in the sandwiched region. The placement of the conductive material 542b is selected to be self-aligned with the opening of the insulator 580. In the transistor 500, the gate electrode is connected between the source electrode and the drain electrode. Therefore, the conductor 560 can be positioned with a margin for alignment. Since the transistor 500 can be formed without any additional steps, the area occupied by the transistor 500 can be reduced. This allows for miniaturization and high integration of semiconductor devices.

[0237] Furthermore, a conductor 560 is formed in a self-aligned manner in the region between the conductors 542a and 542b. Therefore, the conductor 560 has an overlapping area with the conductor 542a or the conductor 542b. This prevents the formation of a gap between the conductor 560 and the conductors 542a and 542b. Therefore, the parasitic capacitance of the transistor 500 can be reduced. It is possible to improve the speed and have high frequency characteristics.

[0238] Conductor 560 may function as a first gate (also called top gate) electrode. The conductor 503 also functions as a second gate (also called a bottom gate) electrode. In this case, the potential applied to the conductor 503 may be changed to the potential applied to the conductor 560. The Vth of the transistor 500 can be controlled by changing it independently without linking it with the In particular, applying a negative potential to the conductor 503 It is possible to increase Vth above 0 V and reduce the off-state current. Applying a negative potential to 503 reduces the potential applied to the conductor 560 compared to not applying a negative potential. The drain current when the potential is 0V can be reduced.

[0239] The conductor 503 is arranged to overlap the oxide 530 and the conductor 560. Therefore, when a potential is applied to the conductor 560 and the conductor 503, The electric field generated by the conductor 503 is connected to the electric field generated by the conductor 503, and the chalcogenide formed in the oxide 530 In this specification and the like, the first gate electrode and the second gate electrode can be covered. The structure of a transistor in which the electric field of the gate electrode electrically surrounds the channel formation region. is called the surrounded channel (S-channel) structure.

[0240] In this specification, the S-channel structure is defined as a structure in which a source electrode and a drain electrode The side and periphery of the oxide 530 in contact with the conductors 542a and 542b functioning as The side of the conductor 542 is I-shaped, just like the channel formation region. The side and periphery of the oxide 530 in contact with the conductor 542a and the conductor 542b are in contact with the insulator 544. Therefore, the I-type region can be formed in the same manner as the channel formation region. can be treated as the same as the high-purity genuine product described later. The S-channel structure is different from the fin structure and the planar structure. By adopting the nel structure, the resistance to the short channel effect is increased. This makes it possible to provide a transistor in which the Neumann effect is unlikely to occur.

[0241] The conductor 503 has the same structure as the conductor 518, and the insulators 514 and 5 Conductor 503a is formed in contact with the inner wall of opening 16, and conductor 503b is formed further inside. It has been completed.

[0242] The insulators 520, 522, 524, and 550 serve as gate insulating films. It has all the functions.

[0243] Here, the insulator 524 in contact with the oxide 530 has more oxygen than the stoichiometric composition. In other words, the insulator 524 has an excess oxygen region. It is preferable that the insulator containing such excess oxygen is connected to the oxide 530. By providing the oxide 530, oxygen vacancies in the oxide 530 are reduced, and the reliability of the transistor 500 is improved. It can improve the performance.

[0244] As an insulator having an excess oxygen region, specifically, an oxide film in which some oxygen is released by heating is used. It is preferable to use a material that releases oxygen when heated. , the amount of oxygen released in terms of oxygen atoms is 1.0 × 10 18 atoms / cm 3 Above, I like Or 1.0 x 10 19 atoms / cm 3 More preferably, 2.0 × 10 19 a toms / cm 3 or more, or 3.0 x 10 20atoms / cm 3 The oxide film is The surface temperature of the film during the TDS analysis was 100°C or higher and 700°C or higher. or in the range of 100°C or higher and 400°C or lower.

[0245] Also, if the insulator 524 has an excess oxygen region, the insulator 522 may be oxygen-resistant (e.g., It has the function of suppressing the diffusion of oxygen (element atoms, oxygen molecules, etc.) (the oxygen mentioned above is less likely to permeate) is preferred.

[0246] The insulator 522 has a function of suppressing the diffusion of oxygen and impurities, and the oxide 530 is effective. The oxygen does not diffuse to the insulator 520 side, which is preferable. This can prevent the insulator 524 and the oxide 530 from reacting with oxygen.

[0247] The insulator 522 may be, for example, aluminum oxide, hafnium oxide, tantalum oxide, or silica. lead zirconate titanate (PZT), strontium titanate (SrTiO3) Alternatively, an insulator containing (Ba,Sr)TiO3 (BST) or the like may be used in a single layer or multilayer. As transistors become smaller and more highly integrated, the thickness of the gate insulating film becomes thinner. This can cause problems such as leakage current. By using high-k material for the gate electrode, the physical film thickness is maintained while the gate insulating film is It is possible to reduce the ground potential.

[0248] In particular, it has the function of suppressing the diffusion of impurities and oxygen (the oxygen is difficult to penetrate) ) Insulating materials containing oxides of one or both of aluminum and hafnium Insulation containing oxides of aluminum and / or hafnium is recommended. As the oxide, aluminum oxide, hafnium oxide, oxide containing aluminum and hafnium It is preferable to use hafnium aluminate or the like. When the insulator 522 is formed, the insulator 522 prevents oxygen from being released from the oxide 530 and prevents transistors from being generated. As a layer for suppressing the intrusion of impurities such as hydrogen from the periphery of the transistor 500 into the oxide 530 It works.

[0249] Alternatively, for example, aluminum oxide, bismuth oxide, or germanium oxide may be added to these insulators. Niobium oxide, silicon oxide, titanium oxide, tungsten oxide, yttrium oxide, Alternatively, zirconium oxide may be added to these insulators, or these insulators may be nitrided. Silicon oxide, silicon oxynitride, or silicon nitride may be stacked on the insulator.

[0250] The insulator 520 is preferably thermally stable. For example, silicon oxide and Silicon oxide nitride and silicon oxynitride are suitable because they are thermally stable. By combining the insulator with silicon oxide or silicon oxynitride, thermally stable and It is possible to obtain an insulator 520 having a laminated structure with a high relative dielectric constant.

[0251] The insulators 520, 522, and 524 each have a laminated structure of two or more layers. In this case, the laminated structure is not limited to the same material, and may be made of different materials. A laminated structure may also be used.

[0252] The transistor 500 has an oxide 530 including a channel formation region, which functions as an oxide semiconductor. For example, the oxide 530 may be an In-Mn-Zn oxide. n oxides (element M is aluminum, gallium, yttrium, copper, vanadium, beryllium Smoke, boron, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum Tungsten, cerium, neodymium, hafnium, tantalum, tungsten, or magnesium It is preferable to use a metal oxide such as one or more selected from the following. The layer 30 may be made of In-Ga oxide or In-Zn oxide.

[0253] Furthermore, it is preferable to use a metal oxide having a low carrier density for the transistor 500. When the carrier density of the metal oxide is reduced, the impurity concentration in the metal oxide is reduced. In this specification and the like, the impurity concentration is low and the defect level density is low. The low level density is called high purity intrinsic or substantially high purity intrinsic. Impurities include, for example, hydrogen, nitrogen, alkali metals, alkaline earth metals, iron, and nickel. , silicon, etc.

[0254] In particular, hydrogen contained in metal oxides reacts with oxygen that bonds with metal atoms to form water, Oxygen vacancies may be formed in the metal oxide. If defects are present, the transistor may have normally-on characteristics. The defect where hydrogen has entered the oxygen vacancy acts as a donor, and electrons, which act as carriers, are generated. In addition, some of the hydrogen atoms bond with oxygen atoms that bond with metal atoms, and the electrons that are carriers Therefore, transistors using metal oxides containing a large amount of hydrogen The capacitor tends to have normally-on characteristics.

[0255] The defect where hydrogen has entered the oxygen vacancy can function as a donor for the metal oxide. It is difficult to quantitatively evaluate the defects. Therefore, in this specification, the metal oxide As a parameter of the oxide, the capacitance of the capacitor, which is assumed to be in a state where no electric field is applied, is used instead of the donor concentration. In other words, the "carrier density" described in this specification and the like is the "donor density." This can sometimes be rephrased as "concentration."

[0256] Therefore, when a metal oxide is used as the oxide 530, the hydrogen in the metal oxide is reduced as much as possible. Specifically, it is preferable that metal oxides are analyzed by secondary ion mass spectrometry ( SIMS (Secondary Ion Mass Spectrometry) The resulting hydrogen concentration is 1×10 20 atoms / cm 3 Less than 1 x 10 19 a toms / cm 3 less than 5 × 10 18 atoms / cm 3 Less than or even better Preferably 1 x 10 18 atoms / cm 3 Impurities such as hydrogen are sufficiently reduced. By using this metal oxide in the channel formation region of a transistor, stable electrical characteristics can be achieved. It can be granted.

[0257] In addition, when a metal oxide is used for the oxide 530, the carrier of the metal oxide in the channel formation region The density is 1×10 18 cm -3 Preferably, it is 1×10 or less. 17 cm -3 less than More preferably, it is 1×10 16 cm -3 More preferably, it is less than 1 x10 13 cm -3 More preferably, it is less than 1×10 12 cm -3 is less than It is more preferable that the lower limit of the carrier density of the metal oxide in the channel formation region is There is no particular limitation, but for example, 1 × 10 -9 cm -3 It can be said that:

[0258] When a metal oxide is used for the oxide 530, the conductor 542 (the conductor 542a and When the conductor 542b) comes into contact with the oxide 530, the oxygen in the oxide 530 is transferred to the conductor 54 2, the conductor 542 may be oxidized. It is highly likely that the conductivity of the conductor 542 will decrease. The diffusion of oxygen into the oxide 530 can be expressed as the absorption of oxygen by the conductor 542. can be done.

[0259] Furthermore, oxygen in the oxide 530 is converted into conductors 542 (conductors 542a and 542b). Diffusion into the oxide 530b and the conductor 542a. A foreign layer may be formed between the oxide 530b and the conductor 542. Since the hetero layer contains a large amount of oxygen, it is presumed that the hetero layer has insulating properties. The three-layer structure of the oxide 530b and the different layer is a three-layer structure consisting of a metal, an insulator, and a semiconductor. It can be considered as MIS (Metal-Insulator-Semiconductor) structure. It is sometimes called a diode junction structure, or a MIS structure. do.

[0260] The different layer is not limited to being formed between the conductor 542 and the oxide 530b. For example, a different layer may be formed between the conductor 542 and the oxide 530c, or between the conductor 54 2 and oxide 530b, and between conductor 542 and oxide 530c. There is a match.

[0261] In addition, the metal oxide that functions as a channel formation region in the oxide 530 is a band gap metal oxide. It is preferable to use a material with a gap of 2 eV or more, preferably 2.5 eV or more. By using metal oxides with a wide band gap, the off-state current of transistors can be reduced. It is possible.

[0262] In addition, the semiconductor material that can be used for the oxide 530 is not limited to the above-mentioned metal oxides. The oxide 530 is a semiconductor material having a band gap (a zero-gap semiconductor). For example, semiconductors of elemental elements such as silicon, gallium arsenide, Compound semiconductors such as silicon, layered materials (atomic layer materials, two-dimensional materials, etc.) that function as semiconductors It is preferable to use a layered structure that functions as a semiconductor. The substance is preferably a semiconductor material.

[0263] In this specification, the term "layered material" is a general term for a group of materials having a layered crystal structure. The layered crystal structure is formed by layers formed by covalent bonds and ionic bonds, It is a structure in which layers are stacked through bonds weaker than covalent or ionic bonds, such as rubbing forces. Layered materials have high electrical conductivity within the unit layer, that is, high two-dimensional electrical conductivity. By using a material that functions as a semiconductor and has high two-dimensional electrical conductivity in the channel formation region, As a result, a transistor with a large on-state current can be provided.

[0264] Layered materials include graphene, silicene, and chalcogenides. Chalcogen is a general term for elements belonging to Group 16. They contain oxygen, sulfur, selenium, tellurium, polonium, and livermorium. Examples of chalcogenides include transition metal chalcogenides and group 13 chalcogenides.

[0265] For example, a transition metal chalcogenide that functions as a semiconductor may be used as the oxide 530. Specific examples of transition metal chalcogenides that can be used as the oxide 530 include: are molybdenum sulfide (typically MoS2), molybdenum selenide (typically MoSe 2), molybdenum telluride (typically MoTe2), tungsten sulfide (typically WS 2), tungsten selenide (typically WSe2), tungsten telluride (typically WTe2), hafnium sulfide (typically HfS2), hafnium selenide (typically HfSe2), zirconium sulfide (typically ZrS2), zirconium selenide (typically Examples include ZrSe2).

[0266] The oxide 530 has the oxide 530a under the oxide 530b, so that the oxide 530 is thicker than the oxide 530a. This can suppress the diffusion of impurities from the structure formed below into the oxide 530b. In addition, by having the oxide 530c on the oxide 530b, the oxide 530c can be formed more efficiently than the oxide 530c. It is possible to suppress the diffusion of impurities from the structure formed above into the oxide 530b. .

[0267] The oxide 530 has a laminated structure of a plurality of oxide layers each having a different atomic ratio of each metal atom. Specifically, in the metal oxide used for the oxide 530a, the constituent elements are preferably The atomic ratio of element M in the oxide 530b is It is preferable that the atomic ratio of the metal oxide used for the oxide 530a is larger than that of the element M. In the oxide 530b, the atomic ratio of element M to In is It is preferable that the atomic ratio of element M to In is larger than that of element M. In the metal oxide used, the atomic ratio of In to element M is It is preferable that the atomic ratio of In to the element M in the metal oxide is larger than that of In. Oxide 530c is a metal oxide that can be used for oxide 530a or oxide 530b. Things can be used.

[0268] The energy of the conduction band minimum of the oxide 530a and the oxide 530c is It is preferable that the energy of the oxide is higher than the energy of the bottom of the conduction band of the oxide. The electron affinity of 530a and oxide 530c is smaller than the electron affinity of oxide 530b. It is preferable.

[0269] Here, at the junctions of oxide 530a, oxide 530b, and oxide 530c, The energy level of the lower conduction band edge changes gradually. The energy level of the conduction band minimum at the junction of 530b and oxide 530c is continuous. In order to achieve this, the oxide 5 At the interface between oxide 530a and oxide 530b, and at the interface between oxide 530b and oxide 530c This is advantageous in that the defect level density of the mixed layer formed by this method is reduced.

[0270] Specifically, oxide 530a and oxide 530b, and oxide 530b and oxide 530c are oxides. By having a common element other than the element (as the main component), a mixed layer with low defect level density is formed. For example, if the oxide 530b is an In-Ga-Zn oxide, the oxide 530b may be an In-Ga-Zn oxide. 30a and oxide 530c, In-Ga-Zn oxide, Ga-Zn oxide, oxide Gallium or the like may be used.

[0271] At this time, the main path of the carriers is the oxide 530b. By configuring the oxide 530c as described above, the interface between the oxide 530a and the oxide 530b and the oxide The defect state density at the interface between the substrate 530b and the oxide 530c can be reduced. Therefore, the influence of interface scattering on carrier conduction is reduced, and the transistor 500 has a high On-current can be obtained.

[0272] On the oxide 530b, a conductor 542 ( Conductor 542a and conductor 542b are provided. Aluminum, chromium, copper, silver, gold, platinum, tantalum, nickel, titanium, molybdenum, tungsten Stainless steel, hafnium, vanadium, niobium, manganese, magnesium, zirconium, Selected from the group consisting of lilium, indium, ruthenium, iridium, strontium, and lanthanum. or an alloy containing the above-mentioned metal elements or a combination of the above-mentioned metal elements. It is preferable to use alloys containing tantalum nitride, titanium nitride, tungsten nitride, etc. , nitrides containing titanium and aluminum, nitrides containing tantalum and aluminum, ruthenium oxide Ruthenium, ruthenium nitride, oxides containing strontium and ruthenium, lanthanum and nickel It is preferable to use oxides containing titanium. and aluminum nitrides, tantalum and aluminum nitrides, ruthenium oxide, Ruthenium nitride, oxides containing strontium and ruthenium, and lanthanum and nickel Oxides are conductive materials that are resistant to oxidation or that maintain conductivity even after absorbing oxygen. Therefore, it is preferable.

[0273] As shown in FIG. 10A, the oxide 530 has the following structure at the interface with the conductor 542 and in the vicinity thereof: When the region 543 (region 543a and region 543b) is formed as the low resistance region At this time, the region 543a functions as either a source region or a drain region, The region 543b functions as the other of the source region and the drain region. A channel forming region is formed in the region sandwiched between region a and region 543b.

[0274] By providing the conductor 542 so as to be in contact with the oxide 530, the oxygen concentration in the region 543 In addition, the metal contained in the conductor 542 and the oxide 530 are mixed in the region 543. In such a case, a metal compound layer containing the components of the region 543 may be formed. The carrier density increases, and the region 543 becomes a low resistance region.

[0275] The insulator 544 is provided to cover the conductor 542 and prevents the conductor 542 from being oxidized. At this time, the insulator 544 is set to cover the side surface of the oxide 530 and to be in contact with the insulator 524. It may also be used.

[0276] Insulator 544 includes hafnium, aluminum, gallium, yttrium, and zirconium. Titanium, tungsten, titanium, tantalum, nickel, germanium, or magnesium A metal oxide containing one or more selected from the above can be used.

[0277] In particular, the insulator 544 may be an oxide of aluminum or hafnium, or both. Insulators containing aluminum oxide, hafnium oxide, aluminum and hafnium It is preferable to use oxides containing hafnium (hafnium aluminate). Hafnium aluminate has higher heat resistance than hafnium oxide film. This is preferable because it is difficult to crystallize during heat treatment. If the material or material does not lose significant conductivity upon absorption of oxygen, the insulator 544 is not required. The structure is not the same as the above. It can be designed appropriately depending on the desired transistor characteristics.

[0278] The insulator 550 functions as a gate insulating film. It is preferable to place the insulator 550 in contact with the upper and side surfaces of the insulator 550. For example, it is preferable to form the insulating material by using an insulating material that releases oxygen atoms. The amount of oxygen released in terms of molecules is 1.0 × 10 18 atoms / cm 3 or more, preferably 1 .0×10 19 atoms / cm 3More preferably, 2.0 × 10 19 atoms / cm 3 or more, or 3.0 x 10 20 atoms / cm 3 The oxide film is as described above. The surface temperature of the film during the TDS analysis was in the range of 100°C to 700°C. is preferred.

[0279] Specifically, silicon oxide having excess oxygen, silicon oxynitride, silicon nitride oxide, and nitride silicon dioxide, fluorine-doped silicon dioxide, carbon-doped silicon dioxide, carbon and Nitrogen-doped silicon oxide and vacant silicon oxide can be used. Silicon oxide and silicon oxynitride are preferred because they are stable to heat.

[0280] An insulator that releases oxygen when heated is used as an insulator 550 and is attached to the top surface of the oxide 530c. By providing the oxide 530b as the insulating layer 550, the oxide 530c passes through the insulating layer 550. Oxygen can be effectively supplied to the channel formation region. Preferably, the concentration of impurities such as water or hydrogen in the insulator 550 is reduced. The thickness of the insulator 550 is preferably 1 nm or more and 20 nm or less.

[0281] In addition, in order to efficiently supply excess oxygen contained in the insulator 550 to the oxide 530, A metal oxide may be provided between the body 550 and the conductor 560. The metal oxide may be an insulator. It is preferable to suppress the diffusion of oxygen from 550 to the conductor 560. The metal oxide prevents excess oxygen from diffusing from the insulator 550 to the conductor 560. In other words, it is possible to suppress a decrease in the amount of excess oxygen supplied to the oxide 530. This can prevent the conductor 560 from being oxidized by excess oxygen. Any material that can be used for the insulator 544 may be used.

[0282] The conductor 560 functioning as the first gate electrode has a two-layer structure in FIGS. 10A and 10B. However, it may have a single layer structure or a laminated structure of three or more layers.

[0283] The conductor 560a is a hydrogen atom, a hydrogen molecule, a water molecule, a nitrogen atom, a nitrogen molecule, a nitrogen oxide molecule ( Conductive material with the function of suppressing the diffusion of impurities such as N2O, NO, NO2, etc., copper atoms, etc. It is preferable to use a material containing at least oxygen (for example, oxygen atoms, oxygen molecules, etc.). It is preferable to use a conductive material that has the function of suppressing the diffusion of the conductive material 5. Since 60a has the function of suppressing the diffusion of oxygen, the oxygen contained in the insulator 550 This can prevent the conductor 560b from being oxidized and the conductivity from decreasing. Examples of conductive materials that have the function of suppressing scattering include tantalum, tantalum nitride, and tantalum fluoride. It is preferable to use ruthenium or ruthenium oxide.

[0284] The conductor 560b is a conductive material mainly composed of tungsten, copper, or aluminum. In addition, since the conductor 560b also functions as a wiring, It is preferable to use a highly conductive material, such as tungsten, copper, or aluminum. The conductor 560b may be a conductive material containing silicon as a main component. For example, a laminated structure of titanium or titanium nitride and the above conductive material may be used. good.

[0285] The insulator 580 is provided on the conductor 542 via the insulator 544. For example, the insulator 580 may be silicon oxide, Silicon oxynitride, silicon nitride oxide, silicon nitride, silicon oxide doped with fluorine, Carbon-doped silicon oxide, carbon- and nitrogen-doped silicon oxide, vacancy-containing acid It is preferable that the material contains silicon oxide or resin. In particular, silicon oxide and oxynitride are preferable. Silicon oxide is preferred because it is thermally stable. In particular, silicon oxide and oxide having vacancies are preferred. Silicon is preferred because it allows for easy formation of an excess oxygen region in a subsequent step.

[0286] The insulator 580 preferably has an excess oxygen region. By providing the insulator 580 in contact with the oxide 530c, the oxygen in the insulator 580 is converted into the oxide 530c, the oxide 530 can be efficiently supplied. It is preferable that the concentration of impurities such as water or hydrogen in the oxygen-containing gas is reduced.

[0287] The opening in the insulator 580 is formed to overlap the region between the conductor 542a and the conductor 542b. As a result, the conductor 560 is inserted through the opening in the insulator 580 and the conductor 542a and the conductor 542b. It is formed so as to be embedded in the region sandwiched between 542b.

[0288] In miniaturizing semiconductor devices, it is required to shorten the gate length. Therefore, the thickness of the conductor 560 must be increased. As a result, the conductor 560 can have a shape with a high aspect ratio. In order to embed the conductor 560 in the opening of the insulator 580, the conductor 560 is formed to have an aspect ratio Even if the shape is high, the conductor 560 can be formed without collapsing during the process. do.

[0289] The insulator 574 is connected to the top surface of the insulator 580, the top surface of the conductor 560, and the top surface of the insulator 550. The insulator 574 is preferably provided in contact with the , an excess oxygen region can be provided in the insulator 550 and the insulator 580. This allows Oxygen can be supplied into the oxide 530 from the excess oxygen region.

[0290] For example, the insulator 574 may be hafnium, aluminum, gallium, yttrium, or di zinc, tungsten, titanium, tantalum, nickel, germanium, or magnesium Metal oxides containing one or more metals selected from the group consisting of sodium, do.

[0291] In particular, aluminum oxide has a high barrier property and is a thin film of 0.5 nm to 3.0 nm. Therefore, the diffusion of hydrogen and nitrogen can be suppressed even if the sputtering method is used. The aluminum oxide film formed by this method is both an oxygen source and a barrier to impurities such as hydrogen. It can also function as a membrane.

[0292] In addition, it is preferable to provide an insulator 581 that functions as an interlayer film over the insulator 574. The insulator 581, like the insulator 524, has a low impurity concentration such as water or hydrogen. It is preferably reduced.

[0293] Also, openings formed in the insulators 581, 574, 580, and 544 Conductor 540a and conductor 540b are placed in the mouth. The conductors 540a and 540b are provided opposite each other with the conductor 560 interposed therebetween. has the same configuration as conductors 546 and 548 described later.

[0294] An insulator 582 is provided on the insulator 581. The insulator 582 is resistant to oxygen and hydrogen. Therefore, the insulator 582 is preferably made of an insulating material having a barrier property. The insulator 582 may be made of a material similar to that of the insulator 514. For example, the insulator 582 may be made of aluminum oxide. It is preferable to use metal oxides such as tantalum oxide, hafnium oxide, and the like.

[0295] In particular, aluminum oxide is a material that can absorb oxygen and hydrogen, which can cause fluctuations in the electrical characteristics of transistors. Therefore, it has a high blocking effect that prevents impurities such as acid and moisture from passing through the membrane. Aluminum oxide is resistant to hydrogen, moisture, etc. during and after the transistor manufacturing process. It is possible to prevent impurities from being mixed into the transistor 500. This can suppress the release of oxygen from the oxide that makes up the transistor. Suitable for use as a protective film against 500.

[0296] Further, an insulator 586 is provided on the insulator 582. The insulator 586 is The same material as that of 20 can be used. In addition, a material with a relatively low dielectric constant is used as the interlayer film. For example, the insulator 586 may be A silicon oxide film, a silicon oxynitride film, or the like can be used.

[0297] Also, the insulator 520, the insulator 522, the insulator 524, the insulator 544, the insulator 580, the insulator The body 574, the insulator 581, the insulator 582, and the insulator 586 are provided with the conductor 546 and and a conductor 548 and the like are embedded therein.

[0298] The conductor 546 and the conductor 548 are connected to the capacitor 600, the transistor 500, or the transistor 500. The conductor 546 functions as a plug or wiring that connects to the transistor 300. The conductor 548 is formed using the same material as the conductor 328 and the conductor 330. It is possible.

[0299] Next, a capacitor 600 is provided above the transistor 500. 00 has a conductor 610, a conductor 620, and an insulator 630.

[0300] Moreover, a conductor 612 may be provided on the conductor 546 and the conductor 548. 12 has a function as a plug or wiring that connects to the transistor 500. The conductor 610 functions as an electrode of the capacitor 600. The conductors 610 can be formed at the same time.

[0301] The conductor 612 and the conductor 610 may be made of molybdenum, titanium, tantalum, or tungsten. a metal film containing an element selected from aluminum, copper, chromium, neodymium, and scandium; Or a metal nitride film containing the above-mentioned elements (tantalum nitride film, titanium nitride film, molybdenum nitride film, etc.) Indium tin oxide (ITO) or tungsten nitride (Tungsten nitride) can be used. Indium oxide containing tungsten oxide, indium zinc oxide containing tungsten oxide oxide, indium oxide with titanium oxide, indium tin oxide with titanium oxide, Conductive materials such as indium zinc oxide and indium tin oxide with added silicon oxide are used You can also do this.

[0302] In FIG. 9, the conductor 612 and the conductor 610 are shown as a single layer structure. For example, a conductive material having a barrier property and a conductive material having a barrier property may be laminated. Conductors with barrier properties are placed between the highly conductive conductors and those with high conductivity. A highly adhesive conductor may be formed.

[0303] The conductor 620 is provided so as to overlap with the conductor 610 with the insulator 630 interposed therebetween. The conductor 620 is made of a conductive material such as a metal material, an alloy material, or a metal oxide material. High-melting-point materials such as tungsten and molybdenum, which have both heat resistance and electrical conductivity, are used. It is preferable to use tungsten, and it is particularly preferable to use tungsten. When forming the structure at the same time as other structures, low-resistance metal materials such as Cu (copper) and Al (aluminum) are used. It is best to use a

[0304] An insulator 650 is provided on the conductor 620 and the insulator 630. The insulator 650 can be formed using the same material as the insulator 320. It may also function as a planarizing film that covers the underlying unevenness.

[0305] By using this structure, a semiconductor device using a transistor having an oxide semiconductor This can suppress fluctuations in electrical characteristics and improve reliability. A transistor including an oxide semiconductor with a large current can be provided. It is possible to provide a transistor including an oxide semiconductor with low current consumption. A semiconductor device with reduced power consumption can be provided. In a semiconductor device using a transistor, miniaturization or high integration can be achieved.

[0306] <Example of transistor structure> Note that the transistor 500 of the semiconductor device described in this embodiment is not limited to the above structure. Hereinafter, examples of structures that can be used for the transistor 500 will be described.

[0307] <Transistor structure example 1> An example of the structure of the transistor 510A will be described with reference to FIGS. 11A, 11B, and 11C. 11A is a top view of transistor 510A. 11C is a cross-sectional view of the portion indicated by the dashed line W1-W2 in FIG. It should be noted that in the top view of FIG. 11A, some elements are omitted for clarity. The diagram is as follows:

[0308] 11A, 11B, and 11C, a transistor 510A and a semiconductor layer 510B functioning as an interlayer film are shown. Insulators 511, 512, 514, 516, 580, and 5 82, and insulator 584. Also shown are transistors 510A and 510B. , a conductor 546 (conductor 546a and conductor 546) functioning as a contact plug b) and a conductor 503 that functions as wiring.

[0309] The transistor 510A has a conductor 560 (conductor 560) that functions as a first gate electrode. a, and conductor 560b), and conductor 505 (conductor 505a and conductor 505b), and an insulator 550 which functions as a first gate insulating film. and an insulator 521, an insulator 522, and an insulator 52 4 and an oxide 530 having a region where a channel is to be formed (oxide 530a, oxide 530 b, and oxide 530c), and a conductor 54 acting as either a source or a drain. 2a, a conductor 542b functioning as the other of the source or drain, and an insulator 574. It has.

[0310] Also, in the transistor 510A shown in FIGS. 11A, 11B, and 11C, the oxide 53 0c, insulator 550, and conductor 560 are inserted into an opening in insulator 580. The oxide 530c, the insulator 550, and the conductor 574 are disposed between the oxide 530c and the insulator 550. 60 is disposed between the conductor 542a and the conductor 542b.

[0311] The insulators 511 and 512 function as interlayer films.

[0312] The interlayer film may be made of silicon oxide, silicon oxynitride, silicon nitride oxide, or aluminum oxide. tantalum oxide, hafnium oxide, zirconium oxide, lead zirconate titanate (PZT ), strontium titanate (SrTiO3) or (Ba,Sr)TiO3 (BST) Insulators such as the following can be used in a single layer or a laminated layer. , aluminum oxide, bismuth oxide, germanium oxide, niobium oxide, silicon oxide, acid Titanium oxide, tungsten oxide, yttrium oxide, and zirconium oxide may also be added. Alternatively, these insulators may be nitrided. Silicon or silicon nitride may also be used in a laminated state.

[0313] For example, the insulator 511 prevents impurities such as water or hydrogen from entering the transistor 510 from the substrate side. It is preferable that the insulating film functions as a barrier film to prevent the inclusion of A. 511 has the function of suppressing the diffusion of impurities such as hydrogen atoms, hydrogen molecules, water molecules, and copper atoms. It is preferable to use an insulating material that is resistant to the impurities (as mentioned above). For example, it has the function of suppressing the diffusion of at least one of oxygen atoms, oxygen molecules, etc. It is preferable to use an insulating material that is difficult for oxygen to permeate. Aluminum oxide or silicon nitride may be used as the material of the electrode 1. Impurities such as water are prevented from diffusing from the substrate side to the transistor 510A side by the insulator 511. It can be suppressed.

[0314] For example, it is preferable that the insulator 512 has a lower dielectric constant than the insulator 511. By using a thin material for the interlayer film, the parasitic capacitance occurring between the wirings can be reduced.

[0315] The conductor 503 is formed so as to be embedded in the insulator 512. The height of the upper surface of the conductor 503 can be made to be approximately the same as the height of the upper surface of the insulator 512. However, the present invention is not limited to this. The conductor 503 may have a multilayer structure of two or more layers. It is preferable to use a highly conductive material containing copper or aluminum as a main component. stomach.

[0316] In transistor 510A, conductor 560 is connected to the first gate (also known as the top gate). The conductor 505 may function as a second gate (bottom gate). In this case, the potential applied to the conductor 505 is changed independently of the potential applied to the conductor 560, In particular, applying a negative potential to the conductor 505 allows the threshold voltage of the capacitor 510A to be controlled. By adding a voltage, the threshold voltage of the transistor 510A is increased above 0 V, and the off-current Therefore, applying a negative potential to the conductor 505 reduces the The drain current when the potential applied to the conductor 560 is 0 V is made smaller than when no potential is applied. It can be made easier.

[0317] In addition, for example, by providing the conductor 505 and the conductor 560 so as to overlap each other, the conductor 560 When a potential is applied to the conductor 505, the electric field generated by the conductor 560 and the electric field generated by the conductor 5 The electric field generated by the oxide 530 is connected to the electric field generated by the oxide 530, and the electric field is covered with the channel forming region formed in the oxide 530. It is possible.

[0318] That is, the electric field of the conductor 560 functioning as the first gate electrode and the electric field of the second gate electrode The electric field of the conductor 505, which functions as an electrode, electrically connects the channel forming region. That is, similar to the transistor 500 described above, It has a ded channel (S-channel) structure.

[0319] The insulators 514 and 516 are interlayer insulating films similar to the insulators 511 and 512. For example, the insulator 514 functions as a film that prevents impurities such as water or hydrogen from entering from the substrate side. It preferably functions as a barrier film that prevents contamination of the transistor 510A. With this configuration, impurities such as hydrogen and water can pass through the insulator 514 from the substrate side to the transistor 5 Diffusion to the 10A side can be suppressed. It is preferable that the dielectric constant is lower than that of 514. By using a material with a low dielectric constant as the interlayer film, The parasitic capacitance occurring between the lines can be reduced.

[0320] Conductor 505, which functions as a second gate, is connected to the openings in insulators 514 and 516. Conductor 505a is formed in contact with the inner wall, and conductor 505b is formed further inside. Here, the height of the upper surfaces of the conductors 505a and 505b and the height of the upper surface of the insulator 516 are The heights of the conductors 505a and 505b can be made approximately the same. Although the configuration in which 505b is stacked is shown, the present invention is not limited to this. For example, the conductor 505 may have a single layer or a laminated structure of three or more layers.

[0321] Here, the conductor 505a prevents the diffusion of impurities such as hydrogen atoms, hydrogen molecules, water molecules, and copper atoms. It is preferable to use a conductive material that has the function of suppressing the impurities (which makes it difficult for the impurities to penetrate). Alternatively, the diffusion of oxygen (for example, at least one of oxygen atoms, oxygen molecules, etc.) is suppressed. It is preferable to use a conductive material that has the above-mentioned function (which is difficult for oxygen to permeate). In the specification, the function of suppressing the diffusion of impurities or oxygen means the function of suppressing the diffusion of the above impurities or oxygen. The function is to suppress the diffusion of any one or all of the above oxygen.

[0322] For example, the conductor 505a has a function of suppressing the diffusion of oxygen, and the conductor 505b This can prevent the conductivity from decreasing due to oxidation.

[0323] When the conductor 505 also functions as a wiring, the conductor 505b is made of tungsten, copper, Alternatively, it is preferable to use a highly conductive material containing aluminum as a main component. In this case, the conductor 503 is not necessarily provided. Although shown in the figure, it may have a laminated structure, for example, titanium or titanium nitride and the above conductive material. It may also be laminated with

[0324] The insulators 521, 522, and 524 function as a second gate insulating film. It has.

[0325] In addition, the insulator 522 preferably has a barrier property. By doing so, impurities such as hydrogen from the periphery of the transistor 510A to the transistor 510A can be prevented from being introduced. It functions as a layer that prevents contamination.

[0326] The insulator 522 may be, for example, aluminum oxide, hafnium oxide, aluminum and hafnium oxide. oxides containing tungsten (hafnium aluminate), tantalum oxide, zirconium oxide, titanium Lead zirconate titanate (PZT), strontium titanate (SrTiO3) or (Ba It is preferable to use an insulator containing, for example, SrTiO3 (BST) in a single layer or a multilayer. As transistors become smaller and more highly integrated, the gate insulating film becomes thinner, and the Insulators that function as gate insulating films may have problems such as high- By using k-material, the gate potential during transistor operation can be reduced while maintaining the physical film thickness. This becomes possible.

[0327] The insulator 521 is preferably thermally stable. For example, silicon oxide and Silicon oxide nitride and silicon oxynitride are suitable because they are thermally stable. By combining the insulator with silicon oxide or silicon oxynitride, thermally stable and It is possible to obtain an insulator 521 having a laminated structure with a high relative dielectric constant.

[0328] 11B and 11C show a three-layer laminated structure as the second gate insulating film. However, it may be a laminated structure of two or less layers, or four or more layers. In that case, the layers must be made of the same material. The structure is not limited to a laminated structure, and may be a laminated structure made of different materials.

[0329] The oxide 530 having a region that functions as a channel formation region is formed by an oxide 530a and an oxide The oxide 530b is formed on the oxide 530a, and the oxide 530c is formed on the oxide 530b. By having the oxide 530a under the oxide 530b, the oxide 530a is formed below the oxide 530a. The diffusion of impurities from the structure to the oxide 530b can be suppressed. By having oxide 530c on 530b, the structure formed above oxide 530c The diffusion of impurities from the structure to the oxide 530b can be suppressed. For this purpose, an oxide semiconductor, which is one of the above-mentioned metal oxides, can be used.

[0330] The oxide 530c is formed in the opening of the insulator 580 through the insulator 574. When the insulator 574 has a barrier property, the insulator 580 This can prevent impurities from diffusing into the oxide 530 .

[0331] The conductor 542 (conductor 542a and conductor 542b) has one functioning as a source electrode. The other functions as a drain electrode.

[0332] The conductor 542a and the conductor 542b are made of aluminum, titanium, chromium, nickel, copper, or the like. , yttrium, zirconium, molybdenum, silver, tantalum, or tungsten Metals or alloys containing metals as the main component can be used. In particular, tantalum nitride, etc. Metal nitride films have barrier properties against hydrogen and oxygen, and also have high oxidation resistance. preferable.

[0333] In addition, although the conductors 542a and 542b are shown as single-layer structures in FIG. 11B, a two-layer structure may be used. For example, it is preferable to stack a tantalum nitride film and a tungsten film. Alternatively, a titanium film and an aluminum film may be stacked. Two-layer structure with aluminum film laminated on top of copper-magnesium-aluminum alloy film a two-layer structure with a copper film laminated on a titanium film; a two-layer structure with a copper film laminated on a tungsten film; It may have a two-layer structure.

[0334] Also, a titanium film or titanium nitride film and an aluminum film overlaid on the titanium film or titanium nitride film are used. A titanium film or a copper film is laminated, and a titanium film or a titanium nitride film is further formed on the aluminum film or a copper film. Three-layer structure: a molybdenum film or molybdenum nitride film and a molybdenum film or molybdenum nitride film. An aluminum film or copper film is laminated on top of the molybdenum film, and then a molybdenum film or There are three-layer structures in which a molybdenum nitride film is formed. A transparent conductive material containing zinc oxide may also be used.

[0335] A barrier layer may be provided on the conductor 542. The barrier layer has resistance to oxygen or hydrogen. It is preferable to use a substance having a barrier property as the insulating material. When the film is formed, oxidation of the conductor 542 can be suppressed.

[0336] The barrier layer may be made of, for example, a metal oxide. In particular, aluminum oxide, oxide Uses insulating films with barrier properties against oxygen and hydrogen, such as hafnium oxide and gallium oxide. Silicon nitride formed by CVD may also be used.

[0337] The barrier layer can broaden the range of material choices for the conductor 542. For example, The conductor 542 is made of tungsten or aluminum, which has low oxidation resistance but high conductivity. In addition, for example, a conductive material that is easy to form a film or process can be used. It is possible.

[0338] The insulator 550 functions as a first gate insulating film. The oxide 530c and the insulator 574 are provided in the opening. preferable.

[0339] As transistors become smaller and more highly integrated, the gate insulating film becomes thinner, which leads to leakage current. In this case, the insulator 550 may function as a second gate insulating film. Similarly, a laminated structure may be used. By using a laminated structure of a thermally stable material and a thin film of a thin film, It is possible to reduce the gate potential during transistor operation. It may have a laminated structure.

[0340] The conductor 560 functioning as the first gate electrode is made up of the conductor 560a and the conductor 560b. The conductor 560a has a conductor 560b on the conductor 505a. The conductor 560a is a hydrogen atom, similar to the conductor 505a. Conductive materials that have the function of suppressing the diffusion of impurities such as hydrogen molecules, water molecules, and copper atoms are used. It is preferable that the oxygen atom is at least one of oxygen atoms, oxygen molecules, etc. It is preferable to use a conductive material that has the function of suppressing the diffusion of .

[0341] Since the conductor 560a has the function of suppressing the diffusion of oxygen, the material selection of the conductor 560b is easy. In other words, by having the conductor 560a, the conductor 560b This suppresses oxidation of the material, thereby preventing a decrease in electrical conductivity.

[0342] Examples of conductive materials that have the function of suppressing oxygen diffusion include tantalum and tantalum nitride. It is preferable to use ruthenium, ruthenium oxide, or the like. The oxide semiconductor that can be used as the oxide 530 can be used as a. In this case, the conductor 560b is formed by sputtering, and the electric It is possible to lower the resistance and make it a conductor. The electrode can be called a tor electrode.

[0343] The conductor 560b is made of a conductive material mainly composed of tungsten, copper, or aluminum. In addition, since the conductor 560b also functions as a wiring, it is preferable to use a conductive material. It is preferable to use a highly conductive material, for example tungsten, copper, or aluminum. The conductor 560b can be formed as a laminated structure. For example, a laminated structure of titanium or titanium nitride and the above conductive material may be used.

[0344] An insulator 574 is disposed between the insulator 580 and the transistor 510A. is an insulating material that has the function of suppressing the diffusion of impurities such as water or hydrogen, and oxygen. For example, it is preferable to use aluminum oxide or hafnium oxide. In addition, other oxides such as magnesium oxide, gallium oxide, germanium oxide, yttrium oxide, zirconium oxide, lanthanum oxide, neodymium oxide or tantalum oxide Any metal oxide, silicon oxide nitride or silicon nitride may be used.

[0345] By including the insulator 574, impurities such as water and hydrogen contained in the insulator 580 are oxidized. The material 530c can suppress diffusion into the oxide 530b through the insulator 550. In addition, the excess oxygen contained in the insulator 580 can prevent the conductor 560 from being oxidized. It is possible.

[0346] Insulators 580, 582, and 584 function as interlayer films.

[0347] The insulator 582, like the insulator 514, prevents impurities such as water or hydrogen from entering the transformer from the outside. It is preferable that the insulating film functions as a barrier insulating film that prevents the metal from being mixed into the resistor 510A.

[0348] In addition, the insulators 580 and 584, like the insulator 516, are thicker than the insulator 582. By using a material with a low dielectric constant as the interlayer film, the This can reduce the parasitic capacitance.

[0349] Also, transistor 510A is embedded in insulator 580, insulator 582, and insulator 584. Electrical connections may be made to other structures through plugs or wires such as embedded conductors 546. stomach.

[0350] The material of the conductor 546 may be a metal material, an alloy material, or a metal, similar to the conductor 505. Conductive materials such as nitride materials or metal oxide materials are used in single or multilayer configurations. For example, high-melting-point materials such as tungsten and molybdenum, which have both heat resistance and electrical conductivity, can be used. Alternatively, it may be made of a low-resistance conductive material such as aluminum or copper. By using a low-resistance conductive material, the wiring resistance can be reduced.

[0351] For example, the conductor 546 is a conductor having barrier properties against hydrogen and oxygen. By using a layered structure of tantalum nitride and highly conductive tungsten, This makes it possible to suppress the diffusion of impurities from the outside while maintaining the conductivity of the material.

[0352] By using the above structure, a transistor including an oxide semiconductor with a large on-state current can be used. Alternatively, a semiconductor device including an oxide semiconductor having a small off-state current can be provided. A semiconductor device using a transistor can be provided. As a result, it is possible to provide a semiconductor device having stable electrical characteristics and improved reliability. can.

[0353] <Transistor structure example 2> An example of the structure of the transistor 510B will be described with reference to FIGS. 12A, 12B, and 12C. 12A is a top view of transistor 510B. 12C is a cross-sectional view of the portion indicated by the dashed line W1-W2 in FIG. It should be noted that in the top view of FIG. 12A, some elements are omitted for clarity. The diagram is as follows:

[0354] Transistor 510B is a modification of transistor 510A. To avoid this, differences from transistor 510A will be mainly described.

[0355] The transistor 510B includes a conductor 542 (conductor 542a and conductor 542b) and The oxide 530c, the insulator 550, and the conductor 560 overlap each other. By adopting this structure, a transistor with high on-state current can be provided. It is possible to provide a transistor with high

[0356] The conductor 560 functioning as the first gate electrode is made up of the conductor 560a and the conductor 560b. The conductor 560a has a conductor 560b on the conductor 505a. The conductor 560a is a hydrogen atom, similar to the conductor 505a. Conductive materials that have the function of suppressing the diffusion of impurities such as hydrogen molecules, water molecules, and copper atoms are used. It is preferable that the oxygen atom is at least one of oxygen atoms, oxygen molecules, etc. It is preferable to use a conductive material that has the function of suppressing the diffusion of .

[0357] The conductor 560a has a function of suppressing the diffusion of oxygen, and thus the width of the conductor 560b can be increased. In other words, the presence of the conductor 560a can suppress oxidation of the conductor 560b. This prevents the conductivity from decreasing.

[0358] In addition, the top and side surfaces of the conductor 560, the side surface of the insulator 550, and the side of the oxide 530c It is preferable to provide an insulator 574 so as to cover the surface. It is recommended to use an insulating material that has the function of suppressing the diffusion of impurities such as hydrogen and oxygen. For example, it is preferable to use aluminum oxide or hafnium oxide. Other examples include magnesium oxide, gallium oxide, germanium oxide, and yttria oxide. Metal oxides such as ammonium, zirconium oxide, lanthanum oxide, neodymium oxide or tantalum oxide Silicon oxide, silicon nitride, silicon oxide, silicon nitride, or the like can be used.

[0359] By providing the insulator 574, oxidation of the conductor 560 can be suppressed. By having the insulator 574, impurities such as water and hydrogen contained in the insulator 580 can be prevented from This can prevent the signal from diffusing to star 510B.

[0360] In addition, an insulator 576 (insulator) having a barrier property is provided between the conductor 546 and the insulator 580. 576a and insulator 576b) may be arranged. The oxygen in the insulating material 580 reacts with the conductor 546, and the conductor 546 is prevented from being oxidized. can be done.

[0361] In addition, by providing an insulator 576 having a barrier property, the conductor used for the plug and wiring For example, the conductor 546 can be made of a material that has the property of absorbing oxygen. By using metal materials with high electrical conductivity, a semiconductor device with low power consumption can be provided. Specifically, tungsten and aluminum have low oxidation resistance, but A material with high conductivity can be used. In addition, for example, a conductive material that is easy to form a film or process can be used. An electric material can be used.

[0362] <Transistor structure example 3> An example of the structure of the transistor 510C will be described with reference to FIGS. 13A, 13B, and 13C. 13A is a top view of transistor 510C. 13C is a cross-sectional view of the portion indicated by the dashed line W1-W2 in FIG. It should be noted that in the top view of FIG. 13A, some elements are omitted for clarity. The diagram is as follows:

[0363] Transistor 510C is a modification of transistor 510A. To avoid this, differences from transistor 510A will be mainly described.

[0364] Transistor 510C shown in FIGS. 13A, 13B, and 13C includes a conductor 542a and an oxide A conductor 547a is disposed between the conductor 542b and the oxide 530b. The conductor 542a (conductor 542b) is disposed on the conductive layer 547b. The oxidized layer extends beyond the upper surface of the conductive body 547a (the conductive body 547b) and the side surface of the conductive body 560. The conductor 547 has a region that contacts the upper surface of the object 530b. Furthermore, the thickness of the conductor 547 is at least It is preferably thicker than body 542 .

[0365] The transistor 510C shown in FIGS. 13A, 13B, and 13C has the above-described configuration. By having the transistor 510A, the conductor 542 can be brought closer to the conductor 560 than the transistor 510A. Alternatively, the end of the conductor 542a and the end of the conductor 542b may be connected to the conductor 560 can be overlapped. This reduces the effective channel length of transistor 510C. This can shorten the time required for the on-state current and improve the frequency characteristics.

[0366] In addition, the conductor 547a (conductor 547b) overlaps with the conductor 542a (conductor 542b). With this configuration, the conductor 546a (the conductor In the etching to form the opening in which the conductor 547a (conductor 546b) is embedded, 7b) acts as a stopper to prevent oxide 530b from being over-etched. This can be done.

[0367] Also, the transistor 510C shown in FIGS. 13A, 13B, and 13C includes an insulator 544 Alternatively, an insulator 545 may be placed on the surface of the substrate 541. Impurities such as hydrogen and excess oxygen enter the transistor 510C from the insulator 580 side. The insulator 545 preferably functions as a barrier insulating film that suppresses the generation of ions. Any insulator can be used for the insulator 544. Examples of the nitride include aluminum nitride, aluminum titanium nitride, titanium nitride, and silicon nitride. Nitride insulators such as silicon or silicon oxynitride may also be used.

[0368] 13A, 13B, and 13C, the transistor 510C shown in FIG. Unlike the transistor 510A shown in FIGS. 11B and 11C, the conductor 505 is formed in a single layer. In this case, an insulating layer 516 may be provided on the patterned conductor 505. An insulating film is formed, and the upper part of the insulating film is treated by a CMP method or the like until the upper surface of the conductor 505 is exposed. Here, it is preferable to improve the flatness of the upper surface of the conductor 505. For example, the average surface roughness (Ra) of the upper surface of the conductor 505 is set to 1 nm or less, preferably 0.5 nm or less. 505. As a result, the thickness of the conductive layer 505 is preferably 0.5 nm or less, more preferably 0.3 nm or less. The insulating layer 530b and the oxide 530c are formed on the substrate 510. ... It is possible to improve the

[0369] <Transistor structure example 4> An example of the structure of the transistor 510D will be described with reference to FIGS. 14A, 14B, and 14C. 14A is a top view of transistor 510D. 14C is a cross-sectional view of the portion indicated by the dashed line W1-W2 in FIG. It should be noted that in the top view of FIG. 14A, some elements are omitted for clarity. The diagram is as follows:

[0370] Transistor 510D is a variation of the transistor described above. In order to clarify the differences between the transistors described above, the following will be mainly described.

[0371] 14A to 14C, the conductor 503 is not provided, and the gate electrode 502 having the function of the second gate is provided. The conductor 505 also functions as a wiring. The metal oxide 552 is disposed on the insulator 550. The conductor 560 has an insulator 570 on it. It has a body 571.

[0372] The metal oxide 552 preferably has a function of suppressing oxygen diffusion. By providing a metal oxide 552 that suppresses oxygen diffusion between the conductive material 560 and the conductive material 560, The diffusion of oxygen into the oxide 530 is suppressed. In addition, oxidation of the conductor 560 by oxygen can be suppressed.

[0373] Note that the metal oxide 552 may function as a part of the first gate. The oxide semiconductor that can be used as the oxide 530 is used as the metal oxide 552. In this case, the conductor 560 is formed by sputtering, and the metal oxide The electrical resistance of the material 552 can be reduced to form a conductive layer. Conductor electrodes.

[0374] The metal oxide 552 may function as a part of the gate insulating film. Therefore, when silicon oxide or silicon oxynitride is used for the insulator 550, 552 is preferably made of a metal oxide, which is a high-k material with a high relative dielectric constant. This laminated structure is stable against heat and has a high dielectric constant. Therefore, the gate voltage applied during transistor operation can be adjusted while maintaining the physical film thickness. In addition, the equivalent oxide thickness (E OT) can be made thinner.

[0375] Although the metal oxide 552 in the transistor 510D is shown as a single layer, it may have a stacked structure of two or more layers. For example, a metal oxide that functions as a part of the gate electrode and a gate insulating film may be used. Alternatively, a metal oxide that functions as a part of the insulating layer may be laminated.

[0376] When the metal oxide 552 functions as a gate electrode, This allows the on-state current of the transistor 510D to be improved without weakening the effect of the electric field. Alternatively, when it functions as a gate insulating film, the insulator 550 and the metal oxide 552 The physical thickness of the oxide 530 keeps the distance between the conductor 560 and the oxide 530. The leakage current between the insulator 560 and the oxide 530 can be suppressed. 550 and a metal oxide 552 are stacked together. 30, and the electric field strength from the conductor 560 to the oxide 530. It can be easily adjusted as needed.

[0377] Specifically, the metal oxide 552 may be an oxide semiconductor that can be used for the oxide 530. By lowering the resistance of the hafnium dioxide, it can be used as the metal oxide 552. Aluminum, gallium, yttrium, zirconium, tungsten, titanium, One selected from the group consisting of tantalum, nickel, germanium, and magnesium, or Metal oxides containing two or more kinds of metals can be used.

[0378] In particular, the insulating layer contains oxides of either or both of aluminum and hafnium. Aluminum oxide, hafnium oxide, oxides containing aluminum and hafnium (haf It is preferable to use hafnium aluminate. In particular, hafnium aluminate is It has higher heat resistance than hafnium oxide film. Therefore, it is possible to prevent crystallization during heat treatment in the subsequent process. The metal oxide 552 is not an essential component. It may be designed appropriately depending on the transistor characteristics.

[0379] The insulator 570 has a function of suppressing the permeation of impurities such as water or hydrogen, and oxygen. It is advisable to use an insulating material, such as aluminum oxide or hafnium oxide. This prevents the conductor 560 from being oxidized by oxygen from above the insulator 570. In addition, it is possible to prevent water or hydrogen from entering the insulating body 570. The impurities are mixed into the oxide 530 through the conductor 560 and the insulator 550. can be suppressed.

[0380] The insulator 571 functions as a hard mask. When processing 0, the side of the conductor 560 is approximately vertical, specifically, the side of the conductor 560 and the substrate The angle formed by the surfaces is between 75 degrees and 100 degrees, preferably between 80 degrees and 95 degrees. can be done.

[0381] The insulator 571 has a function of suppressing the permeation of impurities such as water or hydrogen, and oxygen. By using an insulating material having such a property, the insulating material may also function as a barrier layer. The insulator 570 may not be provided.

[0382] The insulator 571 is used as a hard mask to form the insulator 570, the conductor 560, and the metal oxide 5 52, insulator 550, and oxide 530c are selectively removed to remove these The side surfaces can be made substantially flush and part of the surface of oxide 530b can be exposed.

[0383] Transistor 510D also has regions 531a and 531b on the exposed oxide 530b surface. One of the regions 531a and 531b functions as a source region. The other functions as a drain region.

[0384] The regions 531a and 531b are formed by, for example, an ion implantation method or an ion doping method. , plasma immersion ion implantation, or plasma treatment to remove the exposed oxide. This can be achieved by introducing impurity elements such as phosphorus or boron into the surface of the object 530b. In the present embodiment and the like, "impurity elements" refer to elements other than the main component elements.

[0385] In addition, after exposing a part of the surface of the oxide 530b, a metal film is formed and then heat-treated. By this, the elements contained in the metal film are diffused into the oxide 530b, and the regions 531a and Region 531b may also be formed.

[0386] The region of the oxide 530b into which the impurity element is introduced has a reduced electrical resistivity. The regions 531a and 531b may be referred to as "impurity regions" or "low resistance regions." .

[0387] By using the insulator 571 and / or the conductor 560 as a mask, the regions 531a and and region 531b can be formed in a self-aligned manner. The region 531a and / or the region 531b do not overlap with the conductor 560, and the parasitic capacitance is reduced. In addition, the channel forming region and the source / drain region (region 531a or No offset region is formed between region 531a and region 531b. By forming b in a self-aligned manner, the on-current increases and the threshold This allows for a reduction in the voltage and an improvement in the operating frequency.

[0388] In order to further reduce the off-state current, an off-state current is formed between the channel forming region and the source / drain region. An offset region is a region with high electrical resistivity, and The offset region is a region where the introduction of impurity elements is not performed. This can be achieved by introducing the impurity element described above after forming the insulator 57. 5 also functions as a mask in the same way as the insulator 571. Therefore, the insulator of the oxide 530b Impurity elements are not introduced into the region overlapping with 575, and the electrical resistivity of the region remains high. This can be done.

[0389] The transistor 510D also includes an insulator 570, a conductor 560, a metal oxide 552, and an insulating layer. The insulating layer 575 is formed on the side of the oxide 530c and the insulating layer 550. It is preferable to use an insulator with a low dielectric constant. For example, silicon oxide, silicon oxynitride, or nitride silicon oxide, silicon nitride, fluorine-doped silicon oxide, carbon-doped silicon oxide silicon, carbon and nitrogen doped silicon oxide, silicon oxide with vacancies, or resin It is preferable to use silicon oxide, silicon oxynitride, silicon nitride oxide, etc. In the case where silicon oxide having vacancies is used as the insulator 575, the insulator 575 can be formed in a later process. This is preferable because an excess oxygen region can be easily formed. The insulator 575 is preferable because it is thermally stable. It is preferable to have

[0390] Transistor 510D also has insulator 575 and insulator 574 on oxide 530. The insulator 574 is preferably formed by sputtering. By using this method, it is possible to form an insulator film with little impurities such as water or hydrogen. For example, aluminum oxide may be used as the insulator 574.

[0391] In addition, the oxide film formed by the sputtering method may extract hydrogen from the structure on which the film is formed. Therefore, the insulator 574 absorbs hydrogen and water from the oxide 530 and the insulator 575. This allows the hydrogen concentration in the oxide 530 and the insulator 575 to be reduced.

[0392] <Transistor structure example 5> An example of the structure of the transistor 510E will be described with reference to FIGS. 15A, 15B, and 15C. FIG. 15A is a top view of transistor 510E. 15C is a cross-sectional view of the area indicated by the dashed line W1-W2 in FIG. 15A is a cross-sectional view of the part. Note that in the top view of FIG. 15A, some elements are omitted for clarity. The diagram is as follows:

[0393] Transistor 510E is a variation of the transistor described above. In order to clarify the differences between the transistors described above, the following will be mainly described.

[0394] 15A to 15C, the conductor 542 is not provided, and only a portion of the exposed oxide 530b surface is The area 531a and the area 531b are provided in the area. The oxide 530b serves as the source region and the other serves as the drain region. and an insulator 574.

[0395] The region 531 (region 531a and region 531b) shown in FIG. 15B is formed by oxide 530b. The region 531 is a region where the following elements are added to the region 532. For example, a dummy gate is used. It can be formed by

[0396] Specifically, a dummy gate is provided on the oxide 530b, and the dummy gate is used as a mask. It is preferable to use the oxide 530b and add an element that reduces the resistance of the oxide 530b. However, the element is added to the region that does not overlap with the dummy gate, and a region 531 is formed. The element can be added by mass-separating the ionized source gas. ion implantation, in which ionized source gas is added without mass separation; and ion doping, in which ionized source gas is added without mass separation. , plasma immersion ion implantation, etc. can be used.

[0397] Representative elements that reduce the resistance of the oxide 530 include boron and phosphorus. In addition, hydrogen, carbon, nitrogen, fluorine, sulfur, chlorine, titanium, rare gases, etc. can also be used. Typical examples of noble gases are helium, neon, argon, krypton, and xenonium. The concentration of the element can be measured using SIMS or the like.

[0398] In particular, boron and phosphorus can be used, for example, in the production line of low-temperature polysilicon. This is preferable because existing facilities can be reused, reducing capital investment. can.

[0399] Next, an insulating film that will become an insulator 573 is formed on the oxide 530b and the dummy gate. An insulating film to be the insulator 574 may be formed. By laminating an insulating film 574, the region 531, the oxide 530c, and the insulating film 574 are formed. There may be an area of ​​overlap with the body 550.

[0400] Specifically, after an insulating film to be the insulator 580 is provided on the insulating film to be the insulator 574, By performing CMP processing on the insulating film that will become the insulator 580, a part of the insulating film that will become the insulator 580 is removed. Then, when the dummy gate is removed, the dummy gate and the It is preferable to also remove a part of the insulator 573 that is in contact with the insulator 580. The insulators 574 and 573 are exposed on the side surfaces of the openings, and the oxide film is formed on the bottom surface of the openings. A portion of the region 531 provided in the object 530b is exposed. c), an insulating film that will become the insulator 550, and a conductive film that will become the conductor 560 are formed in this order. After the film formation, the oxide 530c is removed by CMP or the like until the insulator 580 is exposed. 550, and a part of the conductive film that will become the conductor 560. In this way, the transistor shown in FIGS. 15A to 15C can be formed.

[0401] Note that the insulators 573 and 574 are not essential components. The design can be adjusted depending on the requirements.

[0402] The transistors shown in FIGS. 15A to 15C can be adapted from existing devices, and further Since the conductor 542 is not provided, costs can be reduced.

[0403] <Transistor structure example 6> An example of the structure of the transistor 510F will be described with reference to FIGS. 16A, 16B, and 16C. 16A is a top view of transistor 510F. 16C is a cross-sectional view of the area indicated by the dashed line W1-W2 in FIG. It should be noted that in the top view of FIG. 16A, some elements have been omitted for clarity. The diagram is as follows:

[0404] Transistor 510F is a modification of transistor 510A. In order to prevent this, differences from the above transistor will be mainly described.

[0405] In transistor 510A, a portion of insulator 574 is located within an opening in insulator 580. The transistor 51 is provided so as to cover the side surface of the conductor 560. At 0F, openings are formed by removing portions of insulator 580 and insulator 574.

[0406] In addition, an insulator 576 (insulator) having a barrier property is provided between the conductor 546 and the insulator 580. 576a and insulator 576b) may be arranged. The oxygen in the insulating material 580 reacts with the conductor 546, and the conductor 546 is prevented from being oxidized. can be done.

[0407] When an oxide semiconductor is used as the oxide 530, the atomic ratio of each metal atom is different. It is preferable that the oxide 530a has a stacked structure of multiple oxide layers. In the metal oxide, the atomic ratio of element M in the constituent elements is It is preferable that the atomic ratio of the element M in the constituent elements of the oxide is larger than that of the element M. In the metal oxide used in the product 530a, the atomic ratio of element M to In is In the metal oxide used in Ob, the atomic ratio of element M to In is preferably larger than that of element M. In addition, in the metal oxide used for the oxide 530b, the number of In atoms relative to the element M is The ratio is the atomic ratio of In to element M in the metal oxide used for oxide 530a. The oxide 530c is preferably larger than the oxide 530a or the oxide 530b. Metal oxides that can be used for the above can be used.

[0408] The oxide 530a, the oxide 530b, and the oxide 530c preferably have crystallinity. It is particularly preferable to use CAAC-OS. The oxides used have few impurities and defects (oxygen deficiency, etc.), high crystallinity, and a dense structure. Therefore, the source electrode or the drain electrode draws oxygen from the oxide 530b. This prevents the oxide 530b from being oxidized by the heat treatment. Since transistor 510F can be manufactured with high reliability, It is stable with respect to temperature (so-called thermal budget).

[0409] It is to be noted that one or both of the oxide 530a and the oxide 530c may be omitted. The oxide 530 may be a single layer of oxide 530b. When the oxide 530a and oxide 530b are stacked, the oxide 530c is stacked. The energy of the conduction band minimum of oxide 530c is higher than the energy of the conduction band minimum of oxide 530b. In other words, the electron parent of the oxide 530a and the oxide 530c is preferably Preferably, the electron affinity of oxide 530b is smaller than the electron affinity of oxide 530b. It is preferable that Oc uses a metal oxide that can be used for the oxide 530a. Specifically, in the metal oxide used for the oxide 530c, the atomic ratio of element M among the constituent elements is , the atomic ratio of element M in the constituent elements in the metal oxide used for oxide 530b is larger than that In addition, in the metal oxide used for the oxide 530c, the element for In is preferably The atomic ratio of element M to In in the metal oxide used for oxide 530b is It is preferable that the atomic ratio is larger than that of the metal oxide used for the oxide 530b. The atomic ratio of In to the element M in the metal oxide used for the oxide 530c is It is preferable that the atomic ratio of In to M is larger than that of M.

[0410] Here, at the junctions of oxide 530a, oxide 530b, and oxide 530c, The energy level of the lower conduction band edge changes gradually. The energy level of the conduction band minimum at the junction of 530b and oxide 530c is continuous. In order to achieve this, the oxide 5 At the interface between oxide 530a and oxide 530b, and at the interface between oxide 530b and oxide 530c This is advantageous in that the defect level density of the mixed layer formed by this method is reduced.

[0411] Specifically, oxide 530a and oxide 530b, and oxide 530b and oxide 530c are oxides. By having a common element other than the element (as the main component), a mixed layer with low defect level density is formed. For example, if the oxide 530b is an In-Ga-Zn oxide, the oxide 530b may be an In-Ga-Zn oxide. 30a and oxide 530c, In-Ga-Zn oxide, Ga-Zn oxide, oxide Gallium or the like may also be used. The oxide 530c may have a stacked structure. For example, I A stacked structure of n-Ga-Zn oxide and Ga-Zn oxide on the In-Ga-Zn oxide or In-Ga-Zn oxide and gallium oxide on the In-Ga-Zn oxide In other words, a laminated structure of In-Ga-Zn oxide and a layer containing In can be used. A stacked structure with an oxide that is not a conductive layer may be used as the oxide 530c.

[0412] Specifically, the oxide 530a is composed of In:Ga:Zn=1:3:4 [atomic ratio], The oxide 530b may be a metal oxide having an atomic ratio of 1:1:0.5. In:Ga:Zn=4:2:3 [atomic ratio] or 3:1:2 [atomic ratio] metal The oxide 530c may be In:Ga:Zn=1:3:4[ Atomic ratio], In:Ga:Zn=4:2:3 [Atomic ratio], Ga:Zn=2:1 [Atomic ratio] The metal oxide of Ga:Zn=2:5 [atomic ratio] or Ga:Zn=2:5 [atomic ratio] may be used. A specific example of the laminated structure of the object 530c is In:Ga:Zn=4:2:3 [atomics]. In:Ga:Zn=4:2 [atomic ratio] and Ga:Zn=2:1 [atomic ratio] :3 [atomic ratio] and Ga:Zn=2:5 [atomic ratio] stacked structure, In:Ga:Zn =4:2:3 [atomic ratio] and a layered structure with gallium oxide.

[0413] At this time, the main path of the carriers is the oxide 530b. By configuring the oxide 530c as described above, the interface between the oxide 530a and the oxide 530b and the oxide The defect state density at the interface between the substrate 530b and the oxide 530c can be reduced. Therefore, the influence of interface scattering on carrier conduction is reduced, and the transistor 510F has a high The oxide 530c has a laminated structure. In this structure, the defect level density at the interface between the oxide 530b and the oxide 530c is In addition to the effect of lowering the temperature, the constituent elements of the oxide 530c diffuse into the insulator 550. More specifically, the oxide 530c has a laminated structure, and the laminated In order to position an oxide that does not contain In above the structure, In that can diffuse to the insulator 550 side is The insulator 550 functions as a gate insulator, so that the diffusion of In can be suppressed. If the oxide 530c is dispersed, the transistor characteristics will be poor. This makes it possible to provide a highly reliable semiconductor device.

[0414] The oxide 530 is preferably a metal oxide that functions as an oxide semiconductor. For example, the metal oxide that forms the channel formation region of the oxide 530 has a band gap of 2e It is preferable to use a band gap of 5 eV or more, preferably 2.5 eV or more. By using a metal oxide with a wide gap, the off-state current of a transistor can be reduced. By using such a transistor, a semiconductor device with low power consumption can be provided. .

[0415] <Transistor structure example 7> An example of the structure of the transistor 510G will be described with reference to FIGS. 17A and 17B. The transistor 510G is a variation of the transistor 500. Therefore, to avoid repetition, The differences from the above transistor will be mainly described. The structure is the same as that of other transistors included in the semiconductor device according to one embodiment of the present invention, such as the transistor 300. This can also be applied to

[0416] 17A is a cross-sectional view of the transistor 510G in the channel length direction, and FIG. 17B is a cross-sectional view of the transistor 510G in the channel length direction. 17A and 17B are cross-sectional views of the transistor 510G in the channel width direction. The transistor 510G has the insulator 402 and the insulator 404, which is different from the transistor 510G shown in FIGS. 10A and 10B. 0B. Also, the insulator 540a is in contact with the side surface of the conductor 540a. 10, the insulator 551 is provided in contact with the side surface of the conductor 540b. 10A and 10B. Furthermore, the transistor 500 does not have an insulator 520. This is different from the transistor 500 shown in FIGS. 10A and 10B.

[0417] Transistor 510G shown in FIGS. 17A and 17B includes an insulator 402 on an insulator 512. In addition, the insulator 404 is provided on the insulator 574 and on the insulator 402. .

[0418] In the transistor 510G shown in FIGS. 17A and 17B, the insulators 514 and 516 , insulator 522, insulator 524, insulator 544, insulator 580, and insulator 574 are patterned. The insulating material 404 covers these. 04 indicates the top surface of the insulator 574, the side surface of the insulator 574, the side surface of the insulator 580, and the insulator 544 the side of the insulator 524, the side of the insulator 522, the side of the insulator 516, the insulator 514 The oxide 530 and the like are in contact with the side surface of the insulator 402 and the top surface of the insulator 402, respectively. 404 and insulator 402 isolate it from the outside.

[0419] The insulators 402 and 404 are made of at least hydrogen (e.g., hydrogen atoms, hydrogen molecules, etc.). For example, the insulator 402 and the insulator 403 have a high ability to suppress the diffusion of water molecules. The insulator 404 is made of silicon nitride or silicon nitride oxide, which has a high hydrogen barrier property. It is preferable to use a material such as a silicon dioxide film, which prevents hydrogen and other impurities from diffusing into the oxide 530. Therefore, it is possible to suppress the deterioration of the characteristics of the transistor 510G. Therefore, the reliability of the semiconductor device according to one embodiment of the present invention can be improved.

[0420] The insulator 551 includes the insulator 581, the insulator 404, the insulator 574, the insulator 580, and the insulator The insulator 551 is provided in contact with the insulator 544. The insulator 551 has a function of suppressing the diffusion of hydrogen or water molecules. For example, the insulator 551 is preferably made of a material with high hydrogen barrier properties. It is preferable to use an insulator such as silicon nitride, aluminum oxide, or silicon nitride oxide. In particular, silicon nitride is a material with high hydrogen barrier properties, so it is preferable to use it as the insulator 551. By using a material with a high hydrogen barrier property as the insulator 551, Impurities such as water or hydrogen pass through the insulator 580 and the like through the conductors 540a and 540b. This can prevent the diffusion of the silicon dioxide into the oxide 530. It is possible to prevent oxygen from being absorbed by the conductors 540a and 540b. As a result, the reliability of the semiconductor device according to one embodiment of the present invention can be improved.

[0421] FIG. 18 shows transistor 500 and transistor 300 in the same manner as shown in FIGS. 17A and 17B. 10 is a cross-sectional view showing an example of the configuration of a semiconductor device in which the conductor 546 is An insulator 551 is provided on the surface.

[0422] 19A and 19B are modifications of the transistor shown in FIGS. 17A and 17B. FIG. 19A is a cross-sectional view of the transistor in the channel length direction, and FIG. 19B is a cross-sectional view of the transistor in the channel length direction. 19A and 19B are cross-sectional views in the channel width direction. 17A and 17B, the oxide 530c has a two-layer structure of the oxide 530c1 and the oxide 530c2. 17B.

[0423] The oxide 530c1 is formed on the top surface of the insulator 524, the side surface of the oxide 530a, and the top surface of the oxide 530b. The surfaces and sides of the conductors 542a and 542b, the sides of the insulator 544, and the insulator The oxide 530c2 contacts the side of the insulator 580. The oxide 530c2 contacts the insulator 550.

[0424] For example, an In—Zn oxide can be used as the oxide 530c1. When the oxide 530c has a single layer structure, the oxide 530c can be used as the material 530c2. For example, the oxide 530c2 may be made of a material similar to the material that can be used for the oxide 530c2. In:Ga:Zn=1:3:4 [atomic ratio], Ga:Zn=2:1 [atomic ratio], or A metal oxide with an atomic ratio of Ga:Zn=2:5 can be used.

[0425] By forming the oxide 530c into a two-layer structure of the oxide 530c1 and the oxide 530c2, The on-state current of the transistor can be increased compared to when the oxide 530c has a single-layer structure. Therefore, the transistor can be, for example, a power MOS transistor. Note that the oxide 530c included in the transistor illustrated in FIGS. 10A and 10B is also the oxide 5 It can have a two-layer structure of 30c1 and oxide 530c2.

[0426] The transistors shown in FIGS. 19A and 19B include, for example, transistor 500, transistor 300, or both.

[0427] This embodiment may be implemented in appropriate combination with other embodiments described in this specification. It is possible.

[0428] (Fourth embodiment) In this embodiment, the semiconductor device can be used for the OS transistor described in the above embodiment. Metal oxide CAC-OS (Cloud-Aligned Composite Oxide) xide Semiconductor), and CAAC-OS(c-axis Ali About GNED Crystalline Oxide Semiconductor I will explain.

[0429] <Metal oxide composition> CAC-OS or CAC-metal oxide is a material that has a conductive function in some parts. A part of the material has an insulating function, and the entire material has a semiconductor function. Note that CAC-OS or CAC-metal oxide is used for the active layer of a transistor. In this case, the function of conductivity is to allow electrons (or holes) to flow as carriers, and the function of insulation is to allow The function of conductivity is to prevent the flow of electrons, which act as carriers. By making these two functions work in a complementary manner, a switching function (On / Off) is realized. The CAC-OS or CAC-metal oxide can be provided with a function of forming a metal oxide film. In CAC-OS or CAC-metal oxide, each function is separated. This allows you to maximize the functionality of both.

[0430] In addition, CAC-OS or CAC-metal oxide has a conductive region and an insulating region. The conductive region has the above-mentioned conductive function, and the insulating region has the above-mentioned insulating function. In addition, the conductive and insulating regions in the material are formed at the nanoparticle level. In addition, the conductive and insulating regions may be separated by a In addition, the conductive area may be observed as a cloud-like connected area with a blurred periphery. There are cases where this happens.

[0431] In addition, in CAC-OS or CAC-metal oxide, a conductive region and an insulating region are The functional regions are each 0.5 nm to 10 nm, preferably 0.5 nm to 3 nm. The following sizes may be dispersed throughout the material.

[0432] In addition, CAC-OS and CAC-metal oxide have different band gaps. For example, CAC-OS or CAC-metal oxide The component has a wide gap due to the insulating region and a narrow gap due to the conductive region. In this configuration, when a carrier flows, Carriers mainly flow in the low-gap component. The component with a wide gap acts complementary to the component with a narrow gap. In conjunction with this, carriers also flow into the wide-gap component. -OS or CAC-metal oxide is used for the channel formation region of a transistor In this case, the transistor has a high current driving capability in the on-state, i.e., a large on-state current, and High field effect mobility can be obtained.

[0433] That is, CAC-OS or CAC-metal oxide is a matrix composite ( matrix composite, or metal matrix composite It can also be called a trix composite.

[0434] <Metal oxide structure> Oxide semiconductors are divided into single-crystal oxide semiconductors and other non-single-crystal oxide semiconductors. Examples of non-single-crystal oxide semiconductors include CAAC-OS, polycrystalline oxide semiconductors, nc-OS(nanocrystalline oxide semiconductor r), pseudo-amorphous oxide semiconductor (a-like OS) oxide semiconductor) and amorphous oxide semiconductor.

[0435] Furthermore, when focusing on the crystal structure, oxide semiconductors may be classified differently from the above. Here, the classification of crystal structures in oxide semiconductors will be explained with reference to FIG. 20A. FIG. 20A shows an oxide semiconductor, typically IGZO (containing In, Ga, and Zn) FIG. 1 is a diagram illustrating the classification of crystal structures of metal oxides.

[0436] As shown in Figure 20A, IGZO can be broadly divided into amorphous and C It is classified into crystalline and crystal. Amorphous includes completely amorphous. Also, some Crystalline products use CAAC (c-axis aligned c crystalline), nc (nanocrystalline), and CAC (Cl Crystalline Aligned Composite. The classification of NE includes single crystal, poly crystal, and co Completely amorphous crystals are excluded. Includes single crystal and poly crystal.

[0437] The structure within the bold frame in Figure 20A is amorphous and crystalline. It is an intermediate state between the new crystalline state and the new boundary region (New crystalline This structure belongs to the Amorphous and Crystal phases. That is, the structure is in the boundary region between the energetically unstable Amorp It can be said that it has a completely different structure from amorphous or crystal. can.

[0438] The crystal structure of the film or substrate can be determined by X-ray diffraction (XRD). Here, the quartz glass and Crystalli XRD spectrum of IGZO (also called crystalline IGZO) with a crystal structure classified as ne The graphs are shown in Figures 20B and 20C. Figure 20B shows the quartz glass, and Figure 20C shows the crystalline The XRD spectrum of IGZO. The composition of the crystalline IGZO shown in Figure 20C is I The atomic ratio of n:Ga:Zn is approximately 4:2:3. The thickness of the ZO is 500 nm.

[0439] As shown by the arrow in FIG. 20B, the quartz glass exhibited a high purity. In C, the shape of the peak (indicated as "Intensity") is almost symmetrical. As shown by the arrow in Figure 20C, the crystalline IGZO has a peak shape in the XRD spectrum that is The asymmetric shape of the peak in the XRD spectrum indicates the crystal structure. In other words, if the peak shape of the XRD spectrum is not symmetrical, , it cannot be said to be amorphous. The IGZO crystal phase is clearly indicated in the vicinity. The reason why the shape of the spectrum peak is asymmetric is due to the crystalline phase (microcrystals). It is estimated that.

[0440] Specifically, in the XRD spectrum of crystalline IGZO shown in FIG. 20C, The microcrystals have a peak at or near 2θ=31°. When the oxide semiconductor film is evaluated using an X-ray diffraction image, as shown in FIG. In addition, the spectrum width on the lower angle side becomes wider than the peak at or near 2θ=34°. This is because the oxide semiconductor film contains microcrystals with a peak at or near 2θ=31°. This suggests that there is.

[0441] The crystalline structure of the film was also analyzed by nano-beam electron diffraction (NBED). Diffraction patterns observed by electron diffraction (electron microdiffraction patterns) The IGZO film was deposited at room temperature. The diffraction pattern of the IGZO film shown in FIG. 20D is In:Ga:Z Using an oxide target with n=1:1:1 [atomic ratio], the In the ultrafine electron diffraction method, electron diffraction is performed with a probe diameter of 1 nm. It was said.

[0442] As shown in Figure 20D, the diffraction pattern of the IGZO film formed at room temperature shows no halo, A spot-like pattern is observed. This indicates that the IGZO film formed at room temperature is in a crystalline state. It can be concluded that the crystal is neither in a crystallographic nor amorphous state, but in an intermediate state and in an amorphous state. It is estimated that there is no

[0443] CAAC-OS has a c-axis orientation and multiple nanocrystals are connected in the ab-plane direction. The crystal structure has distortion. The distortion is the area where multiple nanocrystals are connected. In the region, the lattice arrangement is changed between a region with a uniform lattice arrangement and another region with a uniform lattice arrangement. Indicates the point where the direction is changing.

[0444] Nanocrystals are basically hexagonal, but they are not limited to regular hexagonal shapes and may be non-regular hexagonal. In addition, the distortion may have lattice arrangements such as pentagons and heptagons. In CAAC-OS, clear grain boundaries are observed even near the strain. It is not possible to confirm the presence of grain boundaries due to distortion of the lattice arrangement. This is because the CAAC-OS has a structure similar to that of the ab-plane. The oxygen atoms are not densely packed, and the bond distance between atoms changes due to the substitution of metal elements. This is thought to be because distortion can be tolerated by, for example,

[0445] The crystal structure in which clear grain boundaries are observed is called polycrystalline. The grain boundaries act as recombination centers, and carriers They may be trapped and cause a decrease in the on-state current of the transistor or a decrease in the field-effect mobility. Therefore, CAAC-OS, which does not have clear grain boundaries, is suitable for transistor semiconductors. CAAC-OS is one of the crystalline oxides with a crystal structure suitable for a conductor layer. For example, In-Zn oxide and In-G α-Zn oxide is more suitable than In oxide because it can suppress the generation of grain boundaries.

[0446] The CAAC-OS also includes a layer containing indium and oxygen (hereinafter referred to as an In layer) and an element M , zinc, and oxygen layers (hereinafter referred to as (M, Zn) layers) are stacked. It is also called a layered structure. Indium and element M are mutually substitutable. When the element M in the (M,Zn) layer is replaced with indium, the (In,M,Zn) layer and Also, when indium in the In layer is replaced with element M, the (In,M) layer It can also be expressed as:

[0447] CAAC-OS is an oxide semiconductor with high crystallinity. Since it is not possible to confirm the grain boundaries, the decrease in electron mobility due to the grain boundaries is unlikely to occur. In addition, the crystallinity of oxide semiconductors can be degraded by the inclusion of impurities and the generation of defects. Therefore, CAAC-OS is an oxide with few impurities and defects (such as oxygen vacancies). Therefore, oxide semiconductors with CAAC-OS have stable physical properties. Therefore, oxide semiconductors having CAAC-OS are heat-resistant and highly reliable. CAAC-OS can withstand the high temperatures (so-called thermal budget) in the manufacturing process. Therefore, when a CAAC-OS is used for an OS transistor, the manufacturing process can be automated. This allows for greater flexibility.

[0448] nc-OS is a material that can be used in microscopic areas (e.g., areas between 1 nm and 10 nm, especially areas between 1 nm and 3 nm). The nc-OS has periodic atomic arrangement in the nanometer range (nm or less). There is no regularity in the crystal orientation between the crystals. Therefore, no orientation is observed throughout the film. Therefore, depending on the analysis method, nc-OS may be distinguished from a-like OS or amorphous oxide semiconductor. It may be difficult to distinguish between the two.

[0449] The a-like OS is an oxide semiconductor with a structure between the nc-OS and amorphous oxide semiconductor. Conductive. A-like OS has voids or low density regions. The OS has lower crystallinity than the nc-OS and CAAC-OS.

[0450] Oxide semiconductors have a variety of structures, each of which has different characteristics. Oxide semiconductors include amorphous oxide semiconductors, polycrystalline oxide semiconductors, a-like OS, and nc The compound may have two or more of -OS and CAAC-OS.

[0451] <Transistors containing oxide semiconductors> Next, a case where the oxide semiconductor is used in a transistor will be described.

[0452] By using the oxide semiconductor in a transistor, a transistor with high field-effect mobility can be realized. Furthermore, a highly reliable transistor can be realized.

[0453] In addition, an oxide semiconductor with low carrier density is preferably used for the transistor. When the carrier density of the oxide semiconductor film is reduced, the impurity concentration in the oxide semiconductor film is In this specification and the like, the impurity concentration is low and the defect level density is low. A low density of recessed levels is called high purity intrinsic or substantially high purity intrinsic.

[0454] Furthermore, a highly purified intrinsic or substantially highly purified intrinsic oxide semiconductor film has a low density of defect states. Therefore, the trap level density may also be low.

[0455] In addition, it takes a long time for the charges trapped in the trap levels of the oxide semiconductor to disappear. Therefore, the trap level density is high. A transistor in which a channel formation region is formed in an oxide semiconductor has unstable electrical characteristics. There are cases where this happens.

[0456] Therefore, in order to stabilize the electrical characteristics of a transistor, the impurity concentration in the oxide semiconductor is In order to reduce the impurity concentration in the oxide semiconductor, It is also preferable to reduce the impurity concentration in the film in contact with the film. Potassium metal, alkaline earth metal, iron, nickel, silicon, etc.

[0457] <Impurities> Here, the influence of each impurity in an oxide semiconductor will be described.

[0458] When oxide semiconductors contain silicon or carbon, which are elements of Group 14, oxide Defect levels are formed in semiconductors. This causes defects in silicon and carbon in oxide semiconductors. The concentration of silicon and carbon near the interface with the oxide semiconductor (Secondary Ion Mass Spectroscopy ( SIMS (Secondary Ion Mass Spectrometry) The resulting concentration is 2 x 10 18 atoms / cm 3 Less than or equal to 2 x 10 17 at oms / cm 3 The following applies.

[0459] In addition, when an alkali metal or an alkaline earth metal is contained in an oxide semiconductor, a defect level is formed. Therefore, alkali metals or alkaline earth metals are not included. A transistor using an oxide semiconductor that has been used in the past tends to be normally on. Therefore, it is preferable to reduce the concentration of alkali metals or alkaline earth metals in the oxide semiconductor. Specifically, the alkali metal or alkaline earth in the oxide semiconductor obtained by SIMS The concentration of metals is 1×10 18 atoms / cm 3 Less than or equal to 2 x 10 16 ato ms / cm 3 Do the following:

[0460] In addition, when nitrogen is contained in an oxide semiconductor, electrons that act as carriers are generated, and the carriers The density increases and it becomes easier to make the oxide semiconductor n-type. The transistor used in the formation region tends to have normally-on characteristics. It is preferable that the nitrogen content in the conductor is reduced as much as possible. For example, in an oxide semiconductor, The nitrogen concentration in the sample was 5×10 19 atoms / cm 3 Less than, preferably 5×10 18 atoms / cm 3 Less than 1×10, more preferably 18 atoms / cm 3 Less than 5 × 10, more preferably 17 atoms / cm 3 The following applies.

[0461] In addition, hydrogen contained in oxide semiconductors reacts with oxygen that bonds with metal atoms to form water. When hydrogen enters the oxygen vacancy, the electrons acting as carriers are released. In addition, some of the hydrogen may combine with the oxygen that is bonded to the metal atom, forming a carrier. Therefore, it is necessary to use an oxide semiconductor containing hydrogen. Therefore, hydrogen in the oxide semiconductor It is preferable that the SIM is reduced as much as possible. The hydrogen concentration obtained by S is 1×10 20 atoms / cm 3 Less than 1x1 0 19 atoms / cm 3 less than 5 × 10 18 atoms / cm 3 less than, More preferably, 1 × 10 18 atoms / cm 3 Less than.

[0462] To use an oxide semiconductor in which impurities are sufficiently reduced for a channel formation region of a transistor This allows stable electrical properties to be imparted.

[0463] This embodiment may be implemented in appropriate combination with other embodiments described in this specification. It is possible. [Explanation of symbols]

[0464] C11: Capacitor element, C12: Capacitor element, C21: Capacitor element, C22: Capacitor element, C41: Capacitor element, C42: Capacitor element, C61: Capacitor element, C62: Capacitor element, DV12: Potential difference ,DV13: potential difference, DV22: potential difference, DV23: potential difference, N11: node, N12: Node, N21: Node, N22: Node, N41: Node, N42: Node, N61: Node, N62: Node, SI1: Signal, SI1_IN: Input terminal, SI1B: Signal, S I1B_IN: Input terminal, SI2: Signal, SI2_IN: Input terminal, SI2B: Signal, S I2B_IN: Input terminal, SO1: Signal, SO1_OUT: Output terminal, SO1B: Signal, SO1B_OUT: Output terminal, SO2: Signal, SO2_OUT: Output terminal, SO2B: Signal SO2B_OUT: output terminal; 10: semiconductor device; 11: transistor; 12: transistor 13: transistor, 14: transistor, 15: transistor, 16: transistor 17: transistor, 18: transistor, 20: semiconductor device, 21: transistor 22: transistor, 23: transistor, 24: transistor, 25: transistor Transistor, 26: Transistor, 31: Transistor, 31_1: Transistor, 31_2 : transistor, 32: transistor, 32_1: transistor, 32_2: transistor 40: semiconductor device, 41: transistor, 42: transistor, 43: transistor , 44: transistor, 45: transistor, 46: transistor, 47: transistor , 48: transistor, 49: transistor, 50: transistor, 60: semiconductor device, 61: transistor, 62: transistor, 63: transistor, 64: transistor, 65: transistor, 66: transistor, 67: transistor, 68: transistor, 69: transistor, 70: transistor, 300: transistor, 311: substrate, 31 3: semiconductor region, 314a: low resistance region, 314b: low resistance region, 315: insulator, 31 6: conductor, 320: insulator, 322: insulator, 324: insulator, 326: insulator, 32 8: conductor, 330: conductor, 350: insulator, 352: insulator, 354: insulator, 35 6: conductor, 360: insulator, 362: insulator, 364: insulator, 366: conductor, 37 0: Insulator, 372: Insulator, 374: Insulator, 376: Conductor, 380: Insulator, 38 2: Insulator, 384: Insulator, 386: Conductor, 402: Insulator, 404: Insulator, 50 0: transistor, 503: conductor, 503a: conductor, 503b: conductor, 505: conductor conductor, 505a: conductor, 505b: conductor, 510: insulator, 510A: transistor , 510B: transistor, 510C: transistor, 510D: transistor, 510 E: transistor, 510F: transistor, 510G: transistor, 511: insulator , 512: insulator, 514: insulator, 516: insulator, 518: conductor, 520: insulator , 521: insulator, 522: insulator, 524: insulator, 530: oxide, 530a: oxide 530b: oxide, 530c: oxide, 530c1: oxide, 530c2: oxide, 531: Area, 531a: Area, 531b: Area, 540a: Conductor, 540b: Conductor , 542:Conductor, 542a:Conductor, 542b:Conductor, 543:Area, 543a:Region region, 543b: region, 544: insulator, 545: insulator, 546: conductor, 546a: conductor Conductor, 546b: Conductor, 547: Conductor, 547a: Conductor, 547b: Conductor, 54 8: conductor, 550: insulator, 551: insulator, 552: metal oxide, 560: conductor, 560a: conductor, 560b: conductor, 570: insulator, 571: insulator, 573: insulator body, 574: insulator, 575: insulator, 576: insulator, 576a: insulator, 576b: Insulator, 580: Insulator, 581: Insulator, 582: Insulator, 584: Insulator, 586: Insulator, 600: Capacitor, 610: Conductor, 612: Conductor, 620: Conductor, 630 :Insulator, 650:Insulator

Claims

[Claim 1] first to eighth transistors; first and second capacitive elements; First and second wirings; first and second input terminals; first and second output terminals; one of the source and the drain of the first transistor is electrically connected to the first wiring; the other of the source and the drain of the first transistor is electrically connected to one of the source and the drain of the second transistor, one terminal of the first capacitive element, and the first output terminal; the other of the source and the drain of the second transistor is electrically connected to the second wiring; a gate of the first transistor is electrically connected to a gate of the fourth transistor, one of a source or a drain of the eighth transistor, one of a source or a drain of the seventh transistor, one terminal of the second capacitive element, and a gate of the sixth transistor; a gate of the second transistor is electrically connected to the other terminal of the first capacitance element, one of the source or the drain of the fourth transistor, one of the source or the drain of the third transistor, the gate of the eighth transistor, and the gate of the fifth transistor; the other of the source and the drain of the fourth transistor is electrically connected to the first wiring; the other of the source and the drain of the third transistor is electrically connected to the second wiring; a gate of the third transistor electrically connected to the second input terminal; the other of the source and the drain of the eighth transistor is electrically connected to the first wiring; the other of the source and the drain of the seventh transistor is electrically connected to the second wiring; a gate of the seventh transistor electrically connected to the first input terminal; one of the source and the drain of the fifth transistor is electrically connected to the first wiring; the other of the source and the drain of the fifth transistor is electrically connected to one of the source and the drain of the sixth transistor, the other terminal of the second capacitive element, and the second output terminal; the other of the source and the drain of the sixth transistor is electrically connected to the second wiring.

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