JP7373838B2 - MIS type semiconductor device - Google Patents

Description

The present invention relates to an MIS semiconductor device and a method for manufacturing the same, and more particularly to a MIS semiconductor device using a diamond semiconductor that is safe, energy saving, has high mobility, and is suitable for high-speed operation, and a method for manufacturing the same.

Semiconductor diamond has a wide bandgap energy (5.47 eV), low dielectric constant (5.7), high breakdown field strength (10 MV/cm), and high carrier saturation velocity (1.5~1.5 for electrons and holes, respectively). 2.7×10 ⁷ cm/s and 0.85–1.2×10 ⁷ cm/s), high thermal conductivity (22 W/cm K) and high carrier mobility (4500 cm ² for electrons and holes, respectively). /V·s and 3800 cm ² /V·s). Here, the above characteristic values are values at room temperature.
Therefore, electronic devices using diamond as a semiconductor are expected to exhibit high power operation, high speed/high frequency operation, high breakdown voltage, and high thermal limits.
In particular, MIS (Metal Insulator Semiconductor) type semiconductor devices using diamond as a semiconductor are attracting attention as core elements for constructing high-performance inverters and high-output high-frequency amplifiers.

Diamond semiconductors have higher carrier mobility than silicon (Si) and silicon carbide (SiC), which are currently used as mainstream materials for power devices. Because of this high mobility, MIS type semiconductor devices using diamond as a semiconductor have the potential to reduce on-resistance, suppress loss, and shorten switching time, allowing the device to operate at high speed.

In recent years, hydrogen-terminated diamond semiconductors have been actively studied (see Non-Patent Document 1).
One reason for this is that in diamond semiconductors, the activation energy of dopants is large and it is difficult to achieve both high carrier density and mobility.
Another factor is that when diamond is manufactured by vapor phase synthesis, the surface of the diamond is automatically almost completely hydrogen-terminated due to the presence of hydrogen atoms, which are an essential process gas in the process of vapor phase synthesis. It can be mentioned as follows.
Hydrogen-terminated diamond semiconductors have the advantage of being able to reduce the number of manufacturing steps, as well as being almost completely hydrogen-terminated, making it easy to obtain high quality.
When the surface of a diamond semiconductor is hydrogen-terminated, an electrically conductive region exists near the surface of the diamond semiconductor, making it a p-type semiconductor.

Recent research has shown that the occurrence of electrical conduction near the surface of hydrogen-terminated diamond semiconductors is due to the contribution of negative charges adsorbed to the surface of the diamond semiconductor or existing in the insulating film formed in contact with the diamond semiconductor. The sources of this negative charge include, for example, adsorbed gases such as nitrogen dioxide (NO ₂ ) and ozone (O ₃ ), solids such as tungsten oxide (WO ₃ ), molybdenum oxide (MoO ₃ ), Vanadium oxide (V ₂ O ₅ ), niobium oxide (Nb ₂ O ₃ ) and aluminum oxide (Al ₂ O ₃ ) are mentioned (Non-Patent Document 2).
In Non-Patent Document 3, unoccupied levels due to oxygen point defects and Al vacancies in the Al ₂ O ₃ film formed on the surface of the diamond become negatively charged, thereby inducing holes near the diamond surface and promoting electrical conduction. It is disclosed that this occurs.
Furthermore, in Non-Patent Document 4, a diamond is exposed to NO ₂ gas in order to accumulate a high concentration of holes near the surface of the diamond, and then sealed with an Al ₂ O ₃ film to fabricate a FET (Field Effect Transistor). An example is disclosed.

IEEE Electron Device Letters, 39, 1373 (2018) Phys. Status Solidi A, 1800681 (2018) Scientific Reports, 7, 42368 (2017) Jpn. J. Appl. Phys. ,56,01AA01(2017) APL Materials, 6, 111105 (2018) Phys. Status Solidi RRL, 1700401 (2018)

As mentioned above, diamond semiconductors have excellent material properties for use in MIS type semiconductor devices, and problems with productivity and quality are being solved by hydrogen termination.
However, when manufacturing an MIS type semiconductor device using a hydrogen-terminated diamond semiconductor layer, the manufactured MIS type semiconductor device has insufficient hole mobility and is not conducive to low power consumption and high speed operation. There was a problem. Further, although it is undesirable for current to flow when no voltage is applied from the viewpoint of power consumption and safety, reduction of this current and improvement of mobility are not compatible with each other.

The problem to be solved by the present invention is to provide an MIS type semiconductor device using a diamond semiconductor that is safe, energy saving, has high mobility, and is suitable for high-speed operation, and a method for manufacturing the same.

The configuration of the present invention is shown below.
(Configuration 1)
A p-type MIS semiconductor device comprising a semiconductor layer, an insulator layer, and a conductor layer, the insulator layer being sandwiched between the semiconductor layer and the conductor layer,
The semiconductor layer is made of diamond in which at least a portion of the portion in contact with the insulator layer is hydrogen-terminated,
An MIS type semiconductor device in which the threshold voltage V _TH is a negative voltage.
(Configuration 2)
The MIS type semiconductor device according to Configuration 1, wherein the insulator layer is made of boron nitride.
(Configuration 3)
3. The MIS type semiconductor device according to configuration 1 or 2, wherein the insulating layer is made of a single crystal of boron nitride.
(Configuration 4)
4. The MIS type semiconductor device according to any one of configurations 1 to 3, wherein the insulating layer is made of hexagonal boron nitride (h-BN).
(Configuration 5)
The MIS type semiconductor device according to any one of configurations 1 to 4, wherein the density of charged impurities present at the interface between the semiconductor layer and the insulator layer is 0 cm ^-2 or more and 5×10 ¹¹ cm ^-2 or less.
(Configuration 6)
The MIS type semiconductor device according to any one of configurations 1 to 4, wherein the density of charged impurities present at the interface between the semiconductor layer and the insulator layer is 0 cm ^-2 or more and 1×10 ¹¹ cm ^-2 or less.
(Configuration 7)
7. The MIS type semiconductor device according to any one of configurations 1 to 6, wherein the conductor layer is made of graphite.
(Configuration 8)
forming a semiconductor layer having a first main surface made of hydrogen-terminated diamond;
forming an insulator layer in contact with at least a portion of the hydrogen-terminated surface of the semiconductor layer;
forming a conductor layer on at least a portion of the insulator layer,
The atmosphere between immediately after forming the semiconductor layer and immediately before forming the insulator layer is one of a group consisting of vacuum, hydrogen gas, an inert gas, and hydrogen gas to which an inert gas is added. A method for manufacturing an MIS type semiconductor device, which is one of the selected methods.
(Configuration 9)
preparing a member having at least a portion of the first main surface where a semiconductor layer made of diamond is exposed;
treating at least a portion of the exposed portion of the semiconductor layer with hydrogen;
forming an insulator layer in contact with at least a portion of the hydrogen-treated portion of the semiconductor layer;
forming a conductor layer on at least a portion of the insulator layer,
The atmosphere from immediately after the hydrogen treatment to immediately before forming the insulating layer is selected from the group consisting of vacuum, hydrogen gas, inert gas, and hydrogen gas to which an inert gas is added. A method for manufacturing an MIS type semiconductor device, which is one of the above.
(Configuration 10)
MIS according to configuration 8 or 9, wherein the atmosphere in which the insulator layer is formed is one selected from the group consisting of vacuum, hydrogen gas, inert gas, and hydrogen gas to which an inert gas is added. A method for manufacturing a type semiconductor device.
(Configuration 11)
11. The method for manufacturing an MIS semiconductor device according to any one of configurations 8 to 10, wherein the insulating layer is made of boron nitride.
(Configuration 12)
12. The method for manufacturing a MIS type semiconductor device according to any one of configurations 8 to 11, wherein the insulating layer is made of a single crystal of boron nitride.
(Configuration 13)
13. The method for manufacturing an MIS semiconductor device according to any one of configurations 8 to 12, wherein the insulating layer is made of hexagonal boron nitride (h-BN).
(Configuration 14)
Manufacturing the MIS type semiconductor device according to any one of configurations 8 to 13, wherein the density of charged impurities present at the interface between the semiconductor layer and the insulator layer is 0 cm ^-2 or more and 5 x 10 ¹¹ cm ^-2 or less. Method.
(Configuration 15)
Manufacturing the MIS type semiconductor device according to any one of configurations 8 to 13, wherein the density of charged impurities present at the interface between the semiconductor layer and the insulator layer is 0 cm ^-2 or more and 1×10 ¹¹ cm ^-2 or less. Method.
(Configuration 16)
16. The method for manufacturing an MIS semiconductor device according to any one of configurations 8 to 15, wherein the inert gas is argon gas.
(Configuration 17)
10. The method for manufacturing an MIS semiconductor device according to configuration 8 or 9, wherein the pressure of the atmosphere is atmospheric pressure.

According to the present invention, it is possible to provide an MIS semiconductor device using a diamond semiconductor that is safe, energy-saving, has high mobility, and is suitable for high-speed operation, and a method for manufacturing the same.

FIG. 1 is a cross-sectional view showing the structure of a MIS type semiconductor device of the present invention. FIG. 2 is a bird's-eye view showing the crystal structure of the semiconductor layer and gate insulator layer of the present invention. FIG. 3 is a manufacturing process diagram showing a manufacturing process of the MIS type semiconductor device of the present invention in cross-sectional view. FIG. 3 is a manufacturing process diagram showing a manufacturing process of the MIS type semiconductor device of the present invention in cross-sectional view. FIG. 3 is a flowchart diagram illustrating the manufacturing process of the MIS type semiconductor device of the present invention. FIG. 3 is a flowchart diagram illustrating the manufacturing process of the MIS type semiconductor device of the present invention. 1 is a cross-sectional view showing the structure of a MIS type semiconductor device of Example 1. FIG. (a) is a plan view seen from above, (b) is a cross-sectional view taken along the line connecting A and A' in (a), and (c) is a cross-sectional view taken along the line connecting A and A' in (a). A cross-sectional view taken along the connecting lines. FIG. 3 is a manufacturing process diagram showing a manufacturing process of the MIS type semiconductor device of Example 1 in cross-sectional view. FIG. 3 is a manufacturing process diagram showing a manufacturing process of the MIS type semiconductor device of Example 1 in cross-sectional view. FIG. 3 is a manufacturing process diagram showing a manufacturing process of the MIS type semiconductor device of Example 1 in cross-sectional view. FIG. 3 is a manufacturing process diagram showing a manufacturing process of the MIS type semiconductor device of Example 1 in cross-sectional view. FIG. 3 is a manufacturing process diagram showing a manufacturing process of the MIS type semiconductor device of Example 1 in cross-sectional view. FIG. 3 is a manufacturing process diagram showing a manufacturing process of the MIS type semiconductor device of Example 1 in cross-sectional view. 1 is a schematic diagram of the configuration of a processing device used in Example 1. FIG. 1 is a schematic diagram of the configuration of a processing device used in Example 1. FIG. A top view photograph of the MIS type semiconductor device manufactured in Example 1. 3 is a characteristic diagram showing the electrical characteristics of the MIS type semiconductor device manufactured in Example 1. FIG. 3 is a characteristic diagram showing the electrical characteristics of the MIS type semiconductor device manufactured in Example 1. FIG. 3 is a characteristic diagram showing the electrical characteristics of the MIS type semiconductor device manufactured in Example 1. FIG. 3 is a characteristic diagram showing the electrical characteristics of the MIS type semiconductor device manufactured in Example 1. FIG. 3 is a characteristic diagram showing the electrical characteristics of the MIS type semiconductor device manufactured in Example 1. FIG. 3 is a characteristic diagram showing the electrical characteristics of the MIS type semiconductor device manufactured in Example 1. FIG. 3 is a characteristic diagram showing the electrical characteristics of the MIS type semiconductor device manufactured in Example 1. FIG. 3 is a characteristic diagram showing the electrical characteristics of the MIS type semiconductor device manufactured in Example 1. FIG.

(Embodiment 1)
DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments for carrying out the present invention will be described below with reference to the drawings.

<Concept>
As mentioned above, in conventional hydrogen-terminated diamond semiconductors, it is thought that negative charges in the insulating film attached to the surface of the diamond semiconductor or in contact with the diamond semiconductor are necessary for electrical conduction near the hydrogen-terminated semiconductor surface. I've been exposed to it.
On the other hand, the inventors believe that this negative charge is not necessarily necessary, but rather that it reduces the mobility of charge carriers through Coulomb scattering and is a factor that causes normally-ion operation (i.e., positive threshold voltage V _TH ). I thought it would be. Therefore, by forming an insulating film in contact with the hydrogen-terminated diamond semiconductor without exposing it to the atmosphere after the hydrogen-terminated diamond surface is formed, we can reduce the negative charge density and achieve high carrier mobility (hole mobility) and It has been found that it is possible to simultaneously obtain a threshold voltage V _TH of .
In the present invention, the threshold voltage V _TH is defined as the square root of the absolute value of the drain current _ID flowing between _the source and the drain (|I _D | ^1/2 ) is linearly approximated and _extrapolated to I _D =0.

Here, the material of the gate insulating film is not limited, and examples thereof include boron nitride, aluminum oxide, silicon oxide, silicon oxynitride, hafnium oxide, titanium oxide, tantalum oxide, yttrium oxide, zirconium oxide, and lanthanum aluminum oxide. , a single-layer film made of calcium fluoride, or a composite film made of these films.
Among these, the gate insulating film is preferably made of boron nitride, more preferably single crystal boron nitride, and even more preferably hexagonal boron nitride (h-BN). Furthermore, when the insulating film is a composite film, the film on the surface in contact with the hydrogen-terminated diamond layer is preferably made of boron nitride, more preferably made of single crystal boron nitride, and has a hexagonal structure. It is even more preferable to use a film made of boron nitride (h-BN).
When boron nitride, preferably single-crystal boron nitride, and even more preferably hexagonal boron nitride (h-BN) is used as the gate insulating film, the hole mobility can be further increased, and the threshold voltage V _TH becomes a larger negative voltage, resulting in improved controllability.

As a result of detailed studies using experiments and simulations, we found that in the method of the present invention, electrical conduction near the surface of a hydrogen-terminated semiconductor is affected by negative energy in the insulating film attached to the surface of the diamond semiconductor and in contact with the diamond semiconductor. The charge is small, and conduction in the diamond semiconductor layer near the hydrogen termination can be controlled by the voltage applied to the gate, and scattering due to negative charges can be suppressed. Furthermore, for example, when h-BN was used as the gate insulating film, the mobility was as high as 5×10 ² cm ² V ⁻¹ s ⁻¹ or more.

In a p-type MIS semiconductor device in which the threshold voltage V _TH is a negative potential, when the gate voltage V _G is 0, the drain current I _D does not necessarily become 0. When the drain current I _D characteristic with respect to the gate voltage V _G changes in the vicinity of V _G =0, that is, the characteristic curve of |I _D | ^1/2 changes from the approximate straight line to the vicinity of I _D =0. When dissociated, a drain current _ID may flow at V _G =0.

However, in the configuration of the present invention, for example, when hexagonal boron nitride (h-BN) is used as the gate insulating film, the approximate straight line of |I _D | ^1/2 does not match well with the actual measurement of |I _D | ^1/2 . , the drain current I _D was less than 4×10 ⁻⁴ mA·mm ⁻¹ at V _G =0. That is, the MIS semiconductor device of the present invention has a normally-off characteristic, that is, no current flows when no voltage is applied to the gate electrode, which is suitable for energy saving. In a standby state in which no voltage is applied to the gate electrode, no drain current _ID flows, which is also excellent in terms of safety. Furthermore, since the hole mobility is high as described above, the on-resistance can be lowered, thereby suppressing conduction loss, resulting in energy savings during operation.

In addition, the inventor has proposed a method for forming a gate insulating film in contact with the surface of the hydrogen-terminated diamond semiconductor layer and making the threshold voltage V _TH a negative voltage. It has been discovered that the atmosphere during this period may be one selected from the group consisting of vacuum, hydrogen gas, inert gas, and hydrogen gas to which an inert gas is added. Note that the steps between the hydrogen-terminated semiconductor layer forming step and the insulator layer forming step include, for example, a sample transportation step and a sample temporary storage step. Here, as the insulating film, as described above, boron nitride is preferable, single crystal boron nitride is more preferable, and hexagonal boron nitride (h-BN) is even more preferable.

<Structure and features>
As shown in FIG. 1, the MIS type semiconductor device 101 of the present invention has a diamond substrate 21, a diamond semiconductor layer 22, a gate insulator layer (gate insulating film) 23, and a conductor layer (gate electrode) 24 as basic components. In addition, it has a structure including a source electrode and its wiring 28, a drain electrode and its wiring 29, a gate electrode wiring 27, an insulating film 25, and a low resistance layer 26. Here, at least the first main surface of the diamond semiconductor layer 22 is subjected to hydrogen termination treatment as described below.
Here, even if the substrate is other than diamond, a thin film made of diamond may be formed on the substrate and used as the diamond semiconductor layer 22. Alternatively, the diamond substrate 21 may be used as a semiconductor layer, and the surface layer portion of the diamond substrate 21 may be used as the diamond semiconductor layer 22. What is important is that the semiconductor layer made of diamond is in contact with the gate insulating film 23. Here, the semiconductor layer (diamond semiconductor layer) 22 made of diamond may contain a dopant.

The present invention relates to an MIS type semiconductor device having a semiconductor layer made of diamond which has excellent material electrical characteristics. One thing is that the gate insulator layer 23 consists of boron nitride, more preferably of single crystal boron nitride, even more preferably of hexagonal boron nitride (h-BN). .

Structures of boron nitride include amorphous boron nitride (a-BN), turbostratic boron nitride (t-BN) with a disordered layered structure in the c-axis direction, and cubic zinc blende-type cubic nitride. Boron (c-BN), hexagonal boron nitride (h-BN) with a hexagonal graphite structure, and wurtzite boron nitride (w-BN) with a hexagonal wurtzite structure are known.
Among these boron nitrides (BN), hexagonal boron nitride (h-BN) is the most preferable for the gate insulator layer 23 from the viewpoint of reducing charge traps in the gate insulator layer 23. More preferably, it is crystalline.

In MIS type semiconductor devices (diamond field effect transistors) using diamond semiconductors that have been reported so far, the gate insulator layer (gate insulating film) is mostly an amorphous film, and is mainly formed by vapor deposition or atomic layer deposition. It was formed by a deposition method (ALD method). The gate insulator layer formed by these methods has a relatively high charge trap density due to atomic defects, etc., and a relatively high interface level is also formed at the interface with the diamond semiconductor layer. Charges captured in such traps (levels) become a factor that reduces carrier mobility.

Diamond consists of a crystal in which each carbon atom is covalently bonded to four surrounding atoms. On the surface of a diamond, there are excess bonds. This dangling bond is unstable and behaves as a surface level.
The dangling bonds can be stabilized by bonding with hydrogen. This state is called hydrogen termination.
For example, the surface of diamond synthesized by chemical vapor phase becomes hydrogen-terminated because it is exposed to hydrogen plasma during synthesis. By using such a hydrogen-terminated diamond surface, the surface state density on the diamond side can be reduced.
On the other hand, the surface of h-BN has no dangling bonds due to its structure. Therefore, the interface state density at the bonding interface between h-BN and hydrogen-terminated diamond is low. Furthermore, the trap density in the insulator layer (insulating film) made of single crystal h-BN is small. For these reasons, carrier scattering due to charges trapped in traps in the insulator layer and interface states can be reduced.

Furthermore, since the dielectric breakdown electric field (parallel to the c-axis) of h-BN is as large as about 12 MV/cm, low on-resistance can be obtained by inducing high-density carriers. Furthermore, the lattice mismatch between h-BN and the hydrogen-terminated diamond (111) surface is about 0.7%, making it suitable for forming an interface with few lattice defects or distortions. This is also useful for improving the characteristics of the MIS type semiconductor device. Here, for reference, a bird's-eye view schematic diagram of the crystal structure of h-BN and hydrogen-terminated diamond crystal (111) is shown in FIG. In FIG. 2, 11 is a carbon atom, 12 is a hydrogen atom, 13 is a boron atom, and 14 is a nitrogen atom.

The gate insulator layer 23 preferably has a thickness of at least 1 atomic pair layer made of boron and nitrogen and at most 300 nm, more preferably at least 1 nm and at most 100 nm.
When the film becomes dense with one atomic pair layer or more, leakage current is suppressed and it becomes easier to function as a gate insulator layer. In order to suppress leakage current including tunnel current, the thickness is preferably 1 nm or more.
Further, when the thickness of the gate insulator layer 23 is 300 nm or less, it becomes easy to obtain sufficient capacitance as an MIS type semiconductor device.

The diamond semiconductor layer 22 is preferably a single crystal with a (100) or (111) crystal plane.

The density of charged impurities present at the interface between the diamond semiconductor layer 22 and the gate insulator layer 23 (concentration at the interface) is 0 cm ^-2 or more and 5 x ¹⁰ cm ^-2 or less, more preferably 0 cm ^-2 or more and 1 x 10 cm -2 or less. It is preferable to set it to ¹¹ cm ⁻² or less. When the density of the charged impurities is within this range, scattering of holes moving through the channel layer formed near the hydrogen-terminated surface of the diamond semiconductor layer 22 due to the charged impurities is suppressed, resulting in an MIS type semiconductor having high mobility. It becomes possible to supply the device 101.
Here, in the MIS semiconductor device 101, holes are induced in the channel layer by a negative potential applied to the gate electrode 24. On the other hand, when no voltage is applied to the gate electrode 24, the MIS type semiconductor device 101 enters a shut-off state and enters a normally-off operation. When the density of the charged impurity is within the above range, the number of holes induced by the charged impurity is extremely small, so the leakage current between the source and drain when no voltage is applied to the gate electrode 24 is very small.

The inventors removed charged impurities by a relatively simple process of leaving the sample in a vacuum or inert gas environment such as Ar gas from the time the hydrogen was terminated until the hydrogen-terminated surface was covered with the gate insulator layer 23. It has been found that it is possible to keep the density within the range of 0 cm ^-2 or more and 5×10 ¹¹ cm ^-2 or less. It is possible to keep the density of charged impurities within the above range without the need for washing, cleaning heat treatment and surface treatment.

Both diamond and h-BN have wide band gaps (5.47 eV and 5.97 eV), making them suitable for high temperature operation. The fact that h-BN has a high thermal conductivity of 4 W/cm K at room temperature, comparable to that of copper, combined with the high thermal conductivity of diamond (22 W/cm K at room temperature), provides excellent heat transfer from the channel part. Contributes to heat dissipation. Furthermore, h-BN is known to act as a coating material that prevents oxidation at high temperatures of 1000°C. Therefore, it also functions to protect the hydrogen terminations on the diamond surface at high temperatures. On the other hand, the low dielectric constants of diamond and h-BN (5.7 and 5.1 (parallel to the c-axis)) are desirable properties for high speed and high frequency operation.

Note that it is preferable that the gate insulator layer 23 be in direct contact with the surface of the diamond semiconductor layer 22 that has been subjected to the termination treatment, without interposing any layer of water, hydrocarbon, resist residue, or the like. This is because interface states are likely to occur if such layers are sandwiched.

In the conventional structure using an amorphous film such as Al ₂ O ₃ as the gate insulator layer 23 , traps (charge traps) occur in the gate insulator layer 23 and at the interface between the gate insulator layer 23 and the diamond semiconductor layer 22 . It tends to contain a lot. Therefore, carrier conduction is subject to scattering, and carrier mobility becomes low.
On the other hand, in the structure of the present invention using boron nitride, preferably single-crystal boron nitride, more preferably h-BN, even more preferably single-crystal h-BN, as the gate insulator layer (gate insulating film), There tends to be less charge trapping in the insulator layer 23. Therefore, carrier conduction causes less scattering and high carrier mobility can be obtained.

The diamond substrate 21 preferably has few crystal defects, high cleanliness, and a flat, smooth surface so that the diamond semiconductor layer 22 formed thereon is a high-quality crystal with few defects. Further, in order to reduce the influence of surface roughness scattering, it is preferable that the surface of the semiconductor layer is also flat and smooth.

The gate electrode 24 is made of a conductive material having a work function such that the threshold voltage V _TH is a negative voltage. Specifically, a conductive film such as metal, graphite (C), or polysilicon added with a dopant can be used. Examples of metals include copper (Cu), tungsten (W), titanium (Ti), aluminum (Al), chromium (Cr), and tantalum (Ta). In addition, alloys such as AlCu, CuNiFe and NiCr, silicides and polycides such as WSi and TiSi, and metal compounds such as WN, TiN, CrN and TaN can also be used. For the gate electrode 24, an appropriate material may be selected from among these materials, taking into consideration the conductivity, work function, workability, etc. as appropriate.
Note that the threshold voltage V _TH depends on the material of the gate electrode 24, the material and thickness of the gate insulator layer 23, the material of the semiconductor channel layer, impurities and their density, and the like.
Further, when the MIS semiconductor device of the present invention is used as an integrated circuit, various heat treatments are added as part of integration, so the material is selected in consideration of the diffusion of the material, taking these heat treatments into consideration.

The source electrode and its wiring 28, the drain electrode and its wiring 29, and the gate electrode wiring 27 are made of a conductive film such as metal, graphite, or polysilicon doped with a dopant. Examples of metals include gold (Au), silver (Ag), Cu, platinum (Pt), palladium (Pd), W, Ti, Al, Cr, and Ta. Further, alloys such as AlCu, CuNiFe, and NiCr, polycide using W, Ti, etc., and metal compounds such as WN, TiN, CrN, and TaN can also be used.
It is preferable that these conductive films can establish ohmic contact at the portions in contact with the diamond semiconductor layer 22. For example, it is preferable to use a metal having a high work function, such as gold (Au) or palladium (Pd), as the conductive film. These high work function metals are characterized by the ability to make ohmic contact through direct contact. Further, titanium (Ti) can also be used. Here, it is preferable that Ti be annealed and reacted with diamond to form TiC. On the other hand, since Ti is easily oxidized, when making electrical contact with the diamond semiconductor layer 22, a conductive film structure is used in which Ti is laminated from the diamond semiconductor layer 22 side, and a material such as Pt, Au, or W is laminated thereon. It is preferable.

In addition, in order to ensure ohmic contact with the source electrode 28 and drain electrode 29 and to lower the resistance of the diamond semiconductor layer 22 other than the channel portion, the low resistance layer 26 is connected between the diamond semiconductor layer 22 and the source electrode 28 and the drain electrode 29. It is preferable to form it at the interface with. For example, when the source electrode 28 and the drain electrode 29 are made of Ti, the low resistance layer may be TiC formed by annealing.

The insulating film 25 plays a role in the stable operation of the MIS semiconductor device 101 by providing electrical insulation and preventing the diffusion of moisture and impurities. The materials include silicon oxide (SiO ₂ ) film, silicon nitride (SiN) film, silicon oxynitride (SiNO) film, silicon carbide (SiC) film, silicon carbonitride (SiCN) film, silicon carbonitride oxide (SiCNO). Examples include organic films such as alumina (Al ₂ O ₃ ) film, boron nitride (BN) film, and polyimide film.

<Manufacturing method>
Next, a method of manufacturing this MIS type semiconductor device 101 will be explained using FIGS. 3 and 4 showing a cross-sectional structure and FIG. 5 showing a flowchart.
First, as shown in FIG. 3(a), a diamond substrate 21 is prepared. As the diamond substrate, for example, one of Ib type or IIa type with crystal planes of 100 or 111 can be preferably used.
Here, the surface of the diamond substrate 21 is preferably flat (plane) and smooth at the atomic level. As for the electrical characteristics of a field effect transistor, the flatness and smoothness of the interface between the diamond semiconductor layer 22 and the gate insulator layer 23 are important, but in order to make the flatness and smoothness of the interface sufficiently high, It is necessary to sufficiently increase the flatness, smoothness, and cleanliness of the surface of the diamond substrate 21.

Thereafter, as shown in FIG. 3B, a hydrogen-terminated diamond semiconductor layer is epitaxially grown on the diamond substrate 21 to form a hydrogen-terminated diamond semiconductor layer 22 (S1 in FIG. 5).
The hydrogen-terminated diamond semiconductor layer 22 can be formed by, for example, microwave plasma CVD (Chemical Vapor Deposition) using CH ₄ gas and H ₂ gas.
The thickness of the diamond semiconductor layer 22 is preferably 10 nm or more. When the thickness is 10 nm or more, it is possible to suppress the incorporation of impurities from the substrate, especially in the case of an Ib substrate.

A dopant may be added to the diamond semiconductor layer 22. Boron (B) can be used as a hole-based dopant, and phosphorus (P) can be used as an electron-based dopant. The amount of dopant added is preferably 10 ¹⁶ /cm ³ or more and 10 ¹⁹ /cm ³ or less. If it is less than 10 ¹⁶ /cm ³ , the effect of dopant addition is small, and if it exceeds 10 ¹⁹ /cm ³ , it becomes a carrier scattering factor and performance such as mobility deteriorates.

Next, immediately after the surface (at least the first main surface) of the diamond semiconductor layer 22 is hydrogen-terminated, the environment in which the sample is placed is set to a vacuum, hydrogen gas, an inert gas, and a hydrogen gas to which an inert gas is added. Evacuation and/or inert gas replacement is performed so as to become one selected from the group consisting of (S2 in FIG. 5). Examples of the inert gas include noble gases such as Ar gas, Kr gas, and Xe gas, and _N2 gas. Here, any one environment selected from the group consisting of vacuum, hydrogen gas, inert gas, and hydrogen gas to which inert gas is added is maintained at least until immediately before forming an insulating film 23a, which will be described later. Do it like this. By doing so, the amount of charged impurities at the interface between the diamond semiconductor layer 22 and the insulating film 23a is reduced, and high hole mobility can be obtained.

Note that if the next step of forming the insulating film 23a is a process such as CVD that is performed once in a vacuum environment, it is efficient and preferable to leave the sample environment in a vacuum, and if the insulating film 23a is formed by bonding, etc. is preferably placed in an inert gas environment from the viewpoint of work efficiency. In addition, as the inert gas, Ar gas is most preferable, comprehensively considering inertness, ensuring purity, and cost.

When placed in a vacuum, the degree of vacuum is preferably about 1×10 ⁻⁵ Pa in view of the effect and equipment load.
When using an inert gas, atmospheric pressure is preferred for ease of handling. Here, atmospheric pressure refers to pressure in atmospheric environments including low pressure, high pressure, and high places, as well as pressure in a pressurized state such as in a glove box to prevent outside air from being mixed in.
Further, the concentration of oxygen gas (O ₂ gas) in the environment is preferably 0.5 ppm or less, and the dew point is preferably -80° C. or less.
The surface of hydrogen-terminated diamond is chemically stable, and in this level of environment there are few charged impurities, making it possible to obtain a surface condition as a semiconductor layer suitable for obtaining high hole mobility with little scattering of charged impurities. .

Thereafter, as shown in FIG. 3C, an insulating film 23a is formed on the diamond semiconductor layer 22 which has been terminated with hydrogen or the like (S3 in FIG. 5). Here, the insulating film 23a is preferably made of boron nitride, particularly preferably a single crystal of boron nitride, even more preferably h-BN, and even more preferably a single crystal of h-BN. Hereinafter, a case where the insulating film is made of boron nitride, which is highly effective, will be explained as an example.
The insulating film 23a can be formed by bonding boron nitride thin films obtained by cleavage, by chemical vapor deposition such as thermal CVD or plasma CVD, by physical vapor deposition such as sputtering, or by physicochemical vapor deposition. It can be formed by a method or the like. Specific examples include metal-organic chemical vapor deposition (MOCVD) using triethylborane (TEB) and ammonia (NH ₃ ) as source gases and hydrogen (H ₂ ) as a carrier gas, and RF. Examples include molecular beam epitaxy (MBE) using activated nitrogen produced by plasma and boron heated and supplied by an electron gun.
In addition, when forming by bonding a boron nitride thin film obtained by cleaving the insulating film 23a, the bonding environment consists of vacuum, hydrogen gas, an inert gas, and hydrogen gas to which an inert gas is added. Preferably, it is one selected from the group. That is, it is preferable that the environment in the step of forming the insulating film 23a is one selected from the group consisting of vacuum, hydrogen gas, inert gas, and hydrogen gas added with inert gas.

Note that in order to remove adsorbed substances at the interface between the diamond semiconductor layer 22 and the insulating film 23a and to clean the surface of the insulating film 23a, a mixture of inert gas and hydrogen (H ₂ ) gas is used after forming the insulating film 23a. It is preferable to perform annealing using gas. Here, as the inert gas, for example, argon (Ar) can be mentioned.

Thereafter, the gate electrode 24 is formed as shown in FIG. 3(d) (S4 in FIG. 5).
The gate electrode 24 is formed by depositing a conductive material constituting the gate electrode 24 on the insulating film 23a by sputtering, vapor deposition, CVD, bonding, etc., and then forming a resist pattern by lithography. However, there is a method in which etching is subsequently performed. As this etching, dry etching is preferably used from the viewpoint of microfabrication, but wet etching can also be used. In the case of wet etching, damage to the MIS type semiconductor device 101 to be manufactured can be easily suppressed.
Alternatively, a method of forming a resist pattern for lift-off on the insulating film 23a and then depositing a conductive material constituting the gate electrode 24 by a sputtering method, vapor deposition method, CVD method, or the like, and performing lift-off may also be mentioned.

Here, examples of the sputtering method include a DC sputtering method and an RF sputtering method, but the RF sputtering method is more preferable from the viewpoint of throughput. Examples of the vapor deposition method include a heating vapor deposition method and an electron beam vapor deposition method. When polysilicon is used as the material for the gate electrode 24, the CVD method can be preferably used as the method for forming the polysilicon film. At this time, it is preferable to add a dopant such as phosphorus (P) to lower the resistance.

Thereafter, an insulating film 25a is formed by a sputtering method, an ALD method, a CVD method, a bonding method, or a coating method such as SOG (Spin on Glass) (FIG. 4(a)).
Here, since the formed insulating film 25a often contains pores and undesired water that impede stabilization of electrical characteristics, it is preferable to perform annealing.

Subsequently, desired openings are formed in the insulating film 25a and the gate insulating film 23a by lithography and etching to form the insulating film 25 and the gate insulating layer (gate insulating film) 23, respectively (FIG. 4(b)).

Thereafter, a low resistance layer 26 is formed on the exposed surface of the diamond semiconductor layer 22 in the opening to establish ohmic contact between the electrode and the semiconductor layer and to provide low resistance (FIG. 4(c)). The low resistance layer 26 can be obtained by depositing a metal such as Ti or Mo that forms a carbide with diamond, and then annealing to form a metal carbide. Further, for the hydrogen-terminated semiconductor layer, a deposited high work function metal such as Au, Pd, or Pt can be used as a low resistance layer.

Thereafter, a conductive film is deposited, lithography and etching are performed to form a gate electrode wiring 27, a source electrode and its wiring 28, and a drain electrode and its wiring 29 (FIG. 4(d)).
Note that the aforementioned low resistance layer 26 may be formed by performing annealing after forming these electrodes and/or wirings.
Through the above steps, the MIS type semiconductor device 101 having the diamond semiconductor layer 22 and the gate insulator layer 23 made of h-BN is manufactured.

The MIS type semiconductor device 101 of the present invention has high carrier mobility (Hole mobility), low power consumption when off (standby) due to normally-off operation, and high mutual conductance g _m even when on. Since the resistance is low, the semiconductor device consumes little power and is suitable for energy saving. Since almost no electricity is supplied during standby, it is also preferable from a security standpoint.
Therefore, the present invention provides a high-performance MIS type semiconductor device that has both characteristics of mobility and carrier density at a high level.

Although the method for manufacturing a single MIS type semiconductor device 101 has been described above, a MIS type semiconductor device in which a plurality of MIS type semiconductor devices 101 are mounted and integrated can also be manufactured in the same manner. In this case, an insulating layer is provided between each MIS type semiconductor device 101, and element isolation is performed as necessary.

(Embodiment 2)
In the first embodiment, a method for manufacturing the MIS type semiconductor device 101 through the hydrogen-terminated diamond semiconductor layer forming step S1, that is, the step of forming the hydrogen-terminated diamond semiconductor layer 22 on the diamond substrate 21 has been described. .
In the second embodiment, the hydrogen-terminated diamond semiconductor layer forming step S1 is replaced with a diamond semiconductor exposed member preparation step S11 and a hydrogen termination treatment step S12, as shown in FIG. 6, and the other steps are the same as in the first embodiment. The present invention provides an MIS type semiconductor device.

In the second embodiment, first, a member with an exposed diamond semiconductor is prepared (step S11). Examples of the member in which the diamond semiconductor is exposed include a diamond semiconductor substrate and a member in which a part of the first main surface of the diamond semiconductor is exposed and a conductive layer and/or an insulating layer for element isolation is formed in the part. be able to.
Thereafter, at least a portion of the exposed diamond semiconductor is subjected to hydrogen termination treatment (step S12).
Examples of the hydrogen termination treatment include plasma under hydrogen gas or heat treatment. For example, when plasma is used, there is a method in which treatment is performed for 10 minutes using an MP-CVD apparatus under the conditions of a H ₂ flow rate of 500 sccm, a pressure of 4 KPa, a heater setting temperature of 600° C., and a microwave output of 300 W.
Hereinafter, the vacuum or inert gas environment treatment (S13) is the vacuum or inert gas environment treatment (S2) of Embodiment 1, and the boron nitride insulator layer forming step (S14) is the boron nitride insulator layer of Embodiment 1. The formation step (S3) and the conductor layer formation step (S15) may be the same as the conductor layer formation step (S4) of the first embodiment.
As described above, it is possible to provide an MIS type semiconductor device having characteristics similar to those of the first embodiment.

EXAMPLES The present invention will be explained in more detail with reference to examples below, but these examples are given here merely to help understand the present invention, and the present invention is not limited thereto.

(Example 1)
<Element structure>
The element structure of the MIS type semiconductor device 201 of Example 1 will be described with reference to FIG. 7, which is a cross-sectional structural diagram of a main part. Here, FIG. 7(a) is a plan view seen from the top, and FIG. 7(b) and FIG. 7(c) connect A and A' and B and B' in FIG. 7(a), respectively. A cross-sectional view taken along the dashed line is shown. Further, in FIG. 7, in order to explain the configuration in an easy-to-understand manner, the constituent elements are shown in simplified shapes such as rectangles.
This MIS type semiconductor device 201 includes a diamond substrate 31, a hydrogen termination layer 32, a gate insulating film 33, a _gate electrode 34G, a source electrode _37S , a drain electrode _37D , a gate electrode wiring _62G , a source electrode wiring _62S , and a drain. It consists of an electrode wiring _62D and an insulating film 61.
Here, the source electrode _37S and the drain electrode _37D are composed of, from the top, a conductive film 36 made of platinum (Pt) with a thickness of 5 nm, a conductive film 35 made of Ti with a thickness of 5 nm, and a diamond substrate 31 and a conductive film 35. It is composed of a low resistance layer 42 made of titanium carbide (TiC) generated at the interface with Ti.
The gate insulating film 33 is made of hexagonal boron nitride (h-BN) and has a thickness of 23 nm.

The diamond substrate 31 has a hydrogen termination layer 32 in the channel portion located directly under the gate insulating film 33, a low resistance layer 42 made of TiC located directly under the conductive film 35, and an oxygen termination layer 43 in the remaining surface layer portion. Each area is formed.

The gate electrode _34G is made of graphite with a thickness of 20 nm. A gate electrode wiring (bonding pad wiring) _62G is formed on the gate electrode _34G, in which Ti with a thickness of 10 nm and Au with a thickness of 100 nm are sequentially laminated.

The source consists of conductive films for ohmic contact (35 and 36 in FIG. 7, respectively) made of Ti with a thickness of 5 nm and platinum (Pt) with a thickness of 5 nm, and a source electrode wiring (bonding pad wiring) _62S . Here, the source electrode wiring _62S has a structure in which Ti with a thickness of 5 nm, Pt with a thickness of 5 nm, Ti with a thickness of 10 nm, and Au with a thickness of 100 nm are sequentially laminated. Further, in the boundary region between the conductive film 35 and the diamond substrate 31, a low resistance layer 42 made of TiC is formed.
Similarly, the drain consists of conductive films for ohmic contact (35 and 36 in FIG. 7, respectively) made of Ti with a thickness of 5 nm and Pt with a thickness of 5 nm, and a drain electrode wiring (bonding pad wiring) _62D . Here, the drain electrode wiring _62D has a structure in which Ti with a thickness of 5 nm, Pt with a thickness of 5 nm, Ti with a thickness of 10 nm, and Au with a thickness of 100 nm are sequentially laminated, and the conductive film 35 and the diamond substrate 31 A low resistance layer 42 made of TiC is formed in the boundary region.

In addition, in order to ensure that the channel layer 32 is sufficiently insulated from the gate electrode wiring (bonding pad wiring) _62G , the edge portion of the gate insulating film 33 where the gate electrode wiring _62G is formed (the oxygen termination and hydrogen termination regions) is An insulating film 61 for element isolation is formed to cover the boundary) 71. The insulating film 61 is also made of hexagonal boron nitride (h-BN) and has a thickness of 63 nm.

<Production method>
The device manufacturing process will be described below with reference to FIGS. 8 to 13, which are cross-sectional views. Here, Figure 8-10 is a cross-sectional view taken along the line connecting A and A' in Figure 7(a), and Figure 11-13 is a cross-sectional view taken along the line connecting B and B' in Figure 7(a). It is a diagram.

1. Preparation of Substrate A high-temperature, high-pressure synthesized IIa (111) diamond single crystal substrate manufactured by TISNCM Research Institute of Russia was prepared as the diamond substrate 31, and the substrate was cleaned using a hot mixed acid and organic cleaning in a conventional manner. Here, the size of the diamond substrate 31 used was 2.5 mm x 2.5 mm x 0.3 mm.

2. Preparation of Alignment Marks Alignment marks were formed on the diamond substrate 31 by laser lithography (not shown).
Here, the process of forming the alignment mark will be described below.
First, a lower resist PMGI-SF6S (manufactured by Microchem) was spin-coated on the surface of the diamond substrate 31 and baked at 180° C. for 5 minutes. Thereafter, photoresist AZ-5214E (manufactured by Merck Performance Materials) was spin-coated and baked at 110° C. for 2 minutes.
Next, an alignment mark pattern was drawn using a high-speed maskless exposure device (manufactured by Nano System Solutions, DL-1000/NC2P). After developing with 2.38% TMAH (tetramethylammonium hydroxide) for a total of 150 seconds, washing was performed with pure water for a total of 120 seconds, and then nitrogen blowing was performed.

Thereafter, Ti to a thickness of 10 nm, Pt to a thickness of 15 nm, Au to a thickness of 60 nm, and Pt to a thickness of 25 nm were sequentially deposited using an electron gun type evaporation apparatus.
Thereafter, the sample was immersed in NMP heated in a water bath set at 80° C., and lift-off was performed.
Finally, after rinsing the diamond substrate 31 with acetone and IPA, nitrogen blowing was performed to form alignment marks at predetermined locations on the diamond substrate 31.

3. Preparation of Ohmic Electrode An electron beam resist gL-2000DR2.0 (manufactured by Gluon Lab) was spin coated on the diamond substrate 31 and baked at 180° C. for 5 minutes.
Thereafter, Espacer 300Z (manufactured by Showa Denko) was spin-coated, and an ohmic electrode pattern was drawn using a 100 kV electron beam drawing device (ELS-7000, manufactured by Elionix). After drawing, it was washed with pure water for 60 seconds to remove the spacer, and then nitrogen blowing was performed. After developing with xylene for 60 seconds and cleaning with IPA for 60 seconds, nitrogen blowing was performed to form a resist pattern 51 on the diamond substrate 31 (FIGS. 8(a) and 11(a)).

Next, a conductive film 35a made of Ti with a thickness of 5 nm and a conductive film 36a made of Pt with a thickness of 5 nm were sequentially deposited using an electron gun type vapor deposition apparatus (FIG. 8(b), FIG. 11(b)).
Thereafter, the sample was immersed in NMP heated in a water bath set at 80° C., and lift-off was performed. After rinsing with acetone and IPA, nitrogen blowing was performed.
Thereafter, annealing was performed for 35 minutes in an H ₂ atmosphere (H ₂ flow rate 500 sccm, pressure 80 Torr) in an MPCVD apparatus (Seki Technotron, AX5200-S) to form a low resistance layer 42 made of TiC at the interface between diamond and Ti. was formed (FIG. 8(c), FIG. 11(c)). The set temperature during annealing was raised to 650°C in approximately 31 minutes and held at 650°C for 35 minutes.

4. Hydrogen termination on the diamond surface and removal of resist residue After the above ohmic electrode formation, the diamond was exposed to hydrogen plasma for 10 minutes in an MPCVD device (AX5200-S, manufactured by Seki Technotron) to hydrogen terminate the surface and remove resist residue. The removal was performed to form a hydrogen termination layer 32 on the exposed surface of the diamond substrate 31 (FIGS. 8(d) and 11(d)).
The conditions for the hydrogen plasma are a H ₂ flow rate of 500 sccm, a pressure of 30 Torr, a heater setting temperature of 600° C., and a microwave output of 300 W.
Furthermore, annealing was performed for 35 minutes in an H ₂ atmosphere (H ₂ flow rate of 500 sccm, pressure of 80 Torr) in another MPCVD apparatus (AX5000, manufactured by Seki Technotron) connectable to the vacuum transfer chamber. The set temperature during annealing was raised to 710°C in approximately 34 minutes and held at 710°C for 35 minutes.
The diamond was exposed to hydrogen plasma for 10 minutes in an MPCVD apparatus (manufactured by Seki Technotron, AX5000) to remove surface adsorbed substances. The conditions for the hydrogen plasma are a H ₂ flow rate of 500 sccm, a pressure of 30 Torr, a heater setting temperature of 670° C., and a microwave output of 300 W.

Subsequently, the diamond substrate 31 subjected to the hydrogen plasma treatment was transported to a glove box in an argon gas atmosphere through a sample transport path kept in vacuum without being exposed to the atmosphere. The details will be explained below using FIGS. 14 and 15, which are cross-sectional views of the device configuration.

FIG. 14 is a cross-sectional view showing an outline of a processing apparatus 1001 for performing hydrogen plasma processing.
The processing apparatus 1001 has a hydrogen termination processing chamber 1011 and a sample transport/temporary storage chamber 1025 as main components. The hydrogen termination processing section E1 is mainly composed of the hydrogen termination processing chamber 1011, and the sample transport section E2 is mainly composed of the sample transport/temporary storage chamber 1025. The E1 section and the E2 section can be separated at the connecting part of the chamber 1027).

The hydrogen termination chamber 1011 is connected to a sample transport/temporary storage chamber 1025 via two gate valves 1024 and 1026 and a transport intermediate chamber 1027, and a sample rod 1029 transports the sample from the hydrogen termination chamber 1011. - It is now possible to transport it to the temporary storage room 1025. Here, the transfer intermediate chamber 1027 is provided with a flange 1028 for connecting an evacuation system, and is closed by the flange (blank flange) 1028 when the evacuation system is not connected.
Further, a turbo exhaust set 1075 is connected to the sample transport/temporary storage chamber 1025 via a pipe 1071, a valve 1072, a flange 1073, and a bellows pipe 1074. Here, the turbo exhaust set 1075 is T-Station 75D (manufactured by Edwards) consisting of a turbo molecular pump and a diaphragm pump.

The hydrogen termination processing chamber 1011 is a processing chamber in which the exposed surface of the first main surface (diamond semiconductor layer) of the diamond substrate 31 is hydrogen-terminated using hydrogen plasma. ) processing room.
The hydrogen termination chamber 1011 is connected to a turbo pump (STP-iX455, manufactured by Edwards) 1013 via a gate valve 1012, and the turbo pump 1013 is connected to a scroll pump (nXDS15i, manufactured by Edwards) 1016 via a valve 1014 and piping 1015. It is connected. For this reason, it has a so-called oil-free vacuum pump configuration. The degree of vacuum 1011 can be read by a vacuum gauge 1063 (ionization vacuum gauge TG200, manufactured by Ampere).

The hydrogen termination chamber 1011 also includes an exhaust path connected to a scroll pump 1016 via a valve 1017 and piping 1018 for the purpose of rough vacuum evacuation. Further, valves 1019 and 1061 and piping 1062 are provided for hydrogen termination treatment control, and a path through which the hydrogen termination treatment chamber 1011 and scroll pump 1016 are connected is also provided.
Furthermore, the hydrogen termination processing chamber 1011 is configured such that a process gas (H ₂ gas) 1023 can be introduced through a valve 1022 .
Note that a Baratron vacuum gauge 1020 is also attached to the hydrogen termination processing chamber 1011 for monitoring the pressure inside the hydrogen termination processing chamber 1011 when performing the hydrogen termination processing.

FIG. 15 is a cross-sectional view showing an outline of a processing apparatus 1002 used for attaching an insulating film 33a made of h-BN to a sample.
The processing apparatus 1002 has a bonding processing chamber (glove box) 1031 and a sample transport/temporary storage chamber 1025 as main components. The sample transport section E2, which mainly consists of the sample transport/temporary storage chamber 1025, is connected to the bonding processing section E3 via a gate valve 1043, so that the sample is not exposed to the atmosphere and is connected to the bonding processing section E2 (globe). box) 1031.

Here, in order to prevent the sample from being exposed to the atmosphere in the intermediate transfer chamber 1027 when the sample is transferred from the sample transfer/temporary storage chamber 1025 to the bonding processing chamber (glove box) 1031, the evacuation system is E4 is connected.
The vacuum exhaust system E4 consists of a chamber 1101 equipped with bellows piping 1109, 1111, a valve 1110, a vacuum gauge (crystal/cold cathode combination gauge CC-10, manufactured by Tokyo Denshi) 1112, an angle valve 1102, and a turbo pump (nEXT300D, Edwards). ) 1103, a valve 1104, a pipe 1107, and a scroll pump (nXDS15i, manufactured by Edwards) 1105, and further includes a pipe 1107 and a valve 1106 for roughly pumping the chamber 1101 with the scroll pump 1105.

The bonding processing chamber 1031 is a processing chamber for bonding the h-BN insulating film that will become the insulating film 33a to the sample, and is connected to a pass box 1034 via a partition door 1032. and is connected to a scroll pump (nXDS15i, manufactured by Edwards) 1037. Note that the bonding processing chamber 1031 is equipped with piping and a valve 1038 for direct exhaust by a scroll pump 1037, and the pass box 1034 is equipped with a pressure gauge 1039.

The bonding processing chamber 1031 is filled with inert gas (Ar gas) at atmospheric pressure.
Ar gas is supplied from an Ar gas cylinder 1052 to the bonding processing chamber 1031 and the pass box 1034 via a pipe 1053. Here, valves 1054 and 1055 are provided in piping 1053 heading toward bonding processing chamber 1031 and pass box 1034, respectively.
In addition, this Ar gas is constantly purified by an inert gas circulation purifier 1040 connected to the bonding processing chamber 1031 via piping 1042, 1045 and valves 1041, 1044, and is purified to an oxygen concentration of 0.5 ppm or less and a dew point of -79. It is kept below ℃. Furthermore, this purified Ar gas can be introduced into the sample transport section E2 via a vacuum exhaust system E4 connected via a valve 1108.
The bonding processing chamber 1031 is a so-called glove box, and is accompanied by butyl rubber gloves for performing bonding work while isolating the atmosphere from the outside. Furthermore, the bonding processing chamber 1031 is connected to an Ar gas cylinder 1052 via a valve 1054 and to a scroll pump 1037 via a valve 1038. The pressure can be adjusted. Furthermore, it is equipped with a microscope (not shown), making it possible to perform bonding work on the order of microns in an environment that is atmospherically (gas) isolated from the outside. The image taken by the microscope can be observed on a monitor outside the bonding processing chamber 1031 without damaging the inert gas environment.
Note that the outer wall of the bonding process chamber 1031 is made of stainless steel and glass, and the internal capacity of the bonding process chamber 1031 is approximately 310L.

The steps after hydrogen termination treatment and before h-BN bonding are shown below.
First, as a pre-process, gate valves 1012, 1024, 1026 and valve 1014 are opened, and using turbo pump 1013 and scroll pump 1016, hydrogen termination chamber 1011, transport intermediate chamber 1027, and sample transport/temporary storage chamber 1025 are opened. Create a vacuum. The vacuum at this time was 3×10 ⁻⁵ Pa or less as measured by the vacuum gauge 1063.
Thereafter, gate valves 1012, 1024, 1026 and valve 1014 were closed, valves 1022, 1019, and 1061 were opened, and the above-described hydrogen termination process was performed. During this process, the valves 1072 and 1026 were opened, and the sample transport/temporary storage chamber 1025 and the intermediate transport chamber 1027 were evacuated using the turbo exhaust set 1075.

After the hydrogen termination process was completed, valves 1022 and 1019 were closed, gate valve 1012 and valve 1014 were opened, and hydrogen termination process chamber 1011 was evacuated using turbo pump 1013 and scroll pump 1016.
Thereafter, valve 1072 was closed and turbo exhaust set 1075 was shut down. Also, the bellows piping 1074 was removed. Gate valves 1024 and 1026 were opened, and sample transfer rod 1029 was used to move the sample to sample transfer/temporary storage chamber 1025. After the movement was completed, the gate valve 1026 was closed.
Thereafter, the gate valve 1012 was closed, the valve 1022 was opened to introduce Ar gas, and the hydrogen termination chamber 1011 and the transport intermediate chamber 1027 were brought to atmospheric pressure, and then the valve 1024 was closed.

Thereafter, the sample transport section E2 was separated from the hydrogen termination processing section E1 at the connection between the gate valve 1024 and the transport intermediate chamber 1027, and the sample transport section E2 and the bonding processing section E3 were connected at the gate valve 1043.
Further, the evacuation system E4 was connected to the sample transport section E2 at the flange 1028, and the transport intermediate chamber 1027 was evacuated by the turbo pump 1103 and the scroll pump 1105. When the vacuum decreased to 1×10 ⁻³ Pa or less, the gate valve 1026 was opened. After closing the angle valve 1102, Ar gas was introduced into the intermediate transport chamber 1027 and the sample transport/temporary storage chamber 1025 via the bellows piping 1111, valves 1108, 1110, chamber 1101, and bellows piping 1109. Here, the bonding processing chamber (glove box) 1031 to which the bellows piping 1111 is connected is in a state purified at atmospheric pressure by an Ar gas cylinder 1052 and an inert gas circulation purifier (Ar gas circulation purifier) 1040. is filled with Ar gas.

Thereafter, the gate valve 1043 was opened and the sample transfer rod 1029 was operated to transfer the sample to the bonding processing chamber 1031. Then, the gate valve 1043 was closed.
After this, h-BN was pasted as shown below.

5. Attaching h-BN (hexagonal boron nitride) As described above, the exposed first main surface of the diamond substrate 31 is hydrogen-terminated in the hydrogen termination chamber 1011. It was transported via a storage room 1025 to a glove box 1031 filled with Ar gas. In this state, the oxygen concentration in the glove box 1031 was 0.6 ppm or less, and the dew point was -79° C. or less.

Single crystal h-BN (synthesized within the National Institute for Materials Science) was cleaved by the Scotch tape method in a glove box 1031. The cleaved h-BN was transferred onto PDMS (polydimethylsiloxane) attached to an acrylic substrate. The h-BN and diamond channel regions on the PDMS film were aligned using an optical microscope, and then the h-BN and diamond were bonded together to form an insulating film 33a (Fig. 9(a), Fig. 12 (a)). Here, it took about 2 hours from when the sample was transported to the glove box 1031 to when the bonding of h-BN was completed.
After that, annealing was performed in the glove box. At this time, the temperature was raised from 20°C to 100°C in 16 minutes and held at 100°C for 30 minutes, the temperature was raised to 200°C in 20 minutes and held at 200°C for 30 minutes, and the temperature was raised to 300°C in 20 minutes and 300°C. A sequence of holding for 3 hours was used.

6. Attaching Graphite Graphite (Kish Graphite, manufactured by Coors Tech) was cleaved using the Scotch tape method in the glove box 1031. The cleaved graphite was transferred onto PDMS attached to an acrylic substrate. The graphite on the PDMS film and the channel region of the diamond were aligned using an optical microscope, and the graphite was bonded onto the h-BN/diamond.
After that, annealing was performed in the glove box 1031. At this time, the temperature was raised from 20°C to 100°C in 16 minutes and held at 100°C for 30 minutes, the temperature was raised to 200°C in 20 minutes and held at 200°C for 30 minutes, and the temperature was raised to 300°C in 20 minutes and 300°C. A sequence of holding for 1 hour was used.

7. Formation of Gate Electrode After the sample was taken out from the glove box 1031, a hole bar pattern was drawn using the above-described electron beam lithography method. Here, the resist is PMMA-A6 (manufactured by Microchem), the drawing is performed by a 125 kV electron beam lithography device (manufactured by Elionix, ELS-F125), and the developer is a mixture of MIBK (methyl isobutyl ketone):IPA = 1:3. liquid was used.
Thereafter, using a CCP-RIE apparatus, dry etching of the graphite in areas other than the area that would become the gate electrode was performed for 3 minutes. The plasma conditions are: N ₂ flow rate of 96 sccm, CHF ₃ flow rate of 2 sccm, O ₂ flow rate of 2 sccm, pressure of 10 Pa, and RF output of 35 W. Note that during this etching, h-BN is etched halfway in the film thickness direction.
Thereafter, the sample was placed in acetone, and the resist used as an etching mask was removed. After cleaning with IPA, nitrogen blowing was performed to form a gate electrode _34G made of graphite. Note that during this etching, the exposed region of the first main surface of the diamond substrate 31 is oxidized to form an oxygen termination layer 43a (FIGS. 9(b) and 12(b)).

8. Shaping of h-BN After forming the gate electrode _34G , a resist pattern 52 was formed by the aforementioned laser lithography (FIGS. 9(c) and 12(c)). The resist is a single layer of AZ-5214E.
Thereafter, h-BN was dry etched for 3 minutes using a CCP-RIE device. The plasma conditions are a N ₂ flow rate of 96 sccm, a CHF ₃ flow rate of 2 sccm, an O ₂ flow rate of 2 sccm, a pressure of 10 Pa, and an RF power of 35 W. Thereafter, the sample was placed in acetone, and the resist used as an etching mask was removed. Note that during this etching, the oxygen termination layer 43a is further oxidized, and the oxygen termination layer 43a changes into a densely oxidized oxygen termination layer 43 (FIGS. 9(d) and 12(d)).

9. Attaching h-BN for device isolation Using the above-mentioned attachment method, attach the gate electrode so that the gate electrode wiring 62 _G from the gate electrode 34 _G does not come into electrical contact with the hydrogen-terminated channel portion 32 . h-BN (61) for running the wiring _62G was bonded to the boundary 71 between the oxygen-terminated and hydrogen-terminated regions to prevent contact (FIGS. 10(a) and 13(a)).

10. Preparation of Wiring Using the laser lithography described above, a resist pattern 53 for forming a gate electrode wiring (62 _G ), a source electrode wiring (62 _S ), a drain electrode wiring (62 _D ), and their respective bonding pads was formed. . The resist is a single layer of AZ-5214E.
Thereafter, Ti with a thickness of 10 nm and Au with a thickness of 100 nm were sequentially deposited using an electron gun type evaporation apparatus to deposit a conductive film 62a made of Ti and Au (FIG. 10(b), FIG. 13(b)). .
Thereafter, the sample is immersed in acetone for lift-off, rinsed with IPA, and then nitrogen blow-dried to form a gate electrode wiring _62G , a source electrode wiring _62S , and a drain electrode wiring _62D having bonding pads. A MIS type semiconductor device 201 was fabricated (FIGS. 10(c) and 13(c)).
For reference, FIG. 16 shows an optical microscope photograph taken from the top of the manufactured MIS type semiconductor device 201.

<Electrical characteristics>
The electrical characteristics of the FET (field effect transistor) of the MIS type semiconductor device 201 manufactured by the method described above were investigated. Here, the measuring instruments include a source measure unit B2901A (manufactured by Keysight Technologies), a function generator 33220A (manufactured by Agilent Technologies), amplifiers 1201 and 1211 (manufactured by DL Instruments), and a digital voltmeter 34401A (manufactured by Agilent Technologies). Technologies) was used. In addition, Hall effect measurements were performed using a refrigerant-free cooling device equipped with a superconducting magnet (manufactured by Niki Kogei Co., Ltd.) and the above measuring instrument.

FIG. 17 shows measurement data of gate voltage and Hall mobility, and FIG. 18 shows measurement data of gate voltage and Hall sheet carrier density. Here, the thickness of the gate insulating film made of h-BN is 23 nm, and the measurement temperature is 300K.
From FIG. 17, it was confirmed that a high Hall mobility exceeding 600 cm ² V ⁻¹ s ⁻¹ was obtained.
Furthermore, from FIG. 18, the more negative voltage is applied to the gate electrode _34G , the more the Hall sheet carrier density increases linearly, and when the voltage applied to the gate electrode _34G is -10V, it becomes 6×10 ¹² cm ^-2 It has been demonstrated that high Hall sheet carrier densities exceeding .

FIG. 19 shows the results of plotting the relationship between Hall mobility and Hall density based on the data in FIGS. 17 and 18. The same figure shows the case where the environment is air after the hydrogen termination treatment on the exposed surface of the diamond substrate 31 until the bonding of the insulating film 33a (h-BN), and the data disclosed in Non-Patent Document 5 (not necessarily the hole (This is not data obtained from effect measurement) is also included. Furthermore, the same figure also shows a theoretical curve of the hole density dependence of hole mobility due to the effects of acoustic phonons, surface roughness, surface charge impurities, and their sum total. Here, the details of the calculation method of the theoretical curve will be described below.

From the following equations (A1) to (A3), the relaxation times τ _imp , τ _ac , and τ _r due to surface negative charge scattering, acoustic phonon scattering, and surface roughness scattering are calculated, respectively, and these are calculated using the following equation (A4). The relaxation time τ due to the entire scattering was calculated.
Here, formulas (A1) to (A4) are based on formulas (1), (2), (4), and (5) of Non-Patent Document 6, respectively, but unlike the Non-Patent Document, they are heavy Calculations were made for the hole band, light hole band, and spin-orbit split-off band. In addition, the effective mass was distinguished between parallel and perpendicular to the surface. Similar to the fabricated sample, the surface of the diamond is assumed to be (111). The respective mobilities were calculated from μ _HH = eτ _HH /m _c ^HH* , μ _LH = eτ _LH /m _c ^LH* , and μ _SO =eτ _SO /m _c ^SO* .

The theoretical curve of mobility μ and carrier density n shown in FIG. 19 was obtained from the following equations (A5) and (A6). Here, in consideration of the fact that in the experiment, the mobility and carrier density are determined by the Hall effect in a low magnetic field, the following equations for mobility and carrier density in a low magnetic field were used.
μ = (n _HH μ _HH ² +n _LH μ _LH ² +n _SO μ _SO ² )/(n _HH μ _HH +n _LH μ _LH +n _SO μ _SO )
...(A5)
n = (n _HH μ _HH +n _LH μ _LH +n _SO μ _SO ) ² /(n _HH μ _HH ² +n _LH μ _LH ² +n _SO μ _SO ² )
...(A6)
Here, n _HH , n _LH , and n _SO are areal carrier densities of holes belonging to the heavy hole band, light hole band, and spin-orbit split-off band, respectively. For a certain total carrier density, how it is distributed among n _HH , n _LH , and n _SO can be determined by solving the Schrödinger equation and Poisson equation simultaneously from the following equations (A7) to (A10). I asked for it.

Here, i represents a state in a heavy hole band HH, a light hole band LH, or a spin-orbit split-off band SO.
m _z ⁱ is the effective mass in the direction perpendicular to the surface (m _z ^HH* , m _z ^LH* , m _z ^SO* ), m _// ⁱ is the effective mass in the direction parallel to the surface (m _c ^HH* , m _c ^LH* , m _cSO ^* ), eφ(z) is the potential energy, E _n ⁱ is the eigenenergy (i = the highest energy of the nth subband of HH, LH, SO), Ψ _n ⁱ is the surface corresponding to the eigenenergy E _n ⁱ The wave function in the vertical direction, E _F is the Fermi level, n _n ⁱ is the areal carrier density of holes satisfying the n-th subband of i=HH, LH, SO, and n _2D is the total hole carrier density.

The parameters used in the calculation are as follows.
Temperature T=300K
Diamond dielectric constant ε _S =5.7
Density ρ=3515 kgm ^-3
Longitudinal acoustic phonon velocity u _l =17536ms ^-1
Deformation potential D _ac =8eV
Root mean square (RMS) surface roughness Δ=0.25nm
Lateral relaxation length of surface roughness L=2nm
Distance from the surface of negative charge d=0
Effective mass in the direction parallel to the surface m _c ^*
Heavy hole band m _c ^HH* =0.299m ₀
Light hole band m _c ^LH* =0.503m ₀
Spin-orbit split-off band m _c ^SO* =0.375m ₀
(m ₀ is static mass)
Effective mass in the direction perpendicular to the surface m _z ^*
Heavy hole band m _z ^HH* =0.763m ₀
Light hole band m _z ^LH* =0.248m ₀
Spin-orbit split-off band m _z ^SO* =0.375m ₀
Spin-orbit gap energy Δ ^SO =6meV
Donor density N _D =1.76×10 ¹⁶ cm ⁻³ (0.1 ppm)

From FIG. 19, hydrogen-terminated diamond is used as the semiconductor layer, h-BN is used as the gate insulating film 33, and the environment from forming the hydrogen-terminated layer to bonding the h-BN is vacuum and Ar gas at atmospheric pressure. The fabricated FET (MIS type semiconductor device) has a hall density range of 2×10 ¹¹ cm ⁻² to 6×10 ¹² cm ⁻² and a high voltage of 5×10 ² cm ² V ⁻¹ s ⁻¹ or more. It can be seen that high Hall mobility can be obtained.
This Hall mobility is about twice as high as that of an FET manufactured in the same structure in an atmosphere environment from the formation of the hydrogen termination layer to the bonding of h-BN. Furthermore, the mobility of diamond FETs reported so far as disclosed in Non-Patent Document 5 (shown in FIG. 19) is significantly higher than the mobility of surface conduction of hydrogen-terminated diamond exposed to the atmosphere. It is.
Furthermore, when comparing the experimental results with the simulation results calculated by incorporating the effects of acoustic phonons, surface roughness, and surface charge impurities, the experimental results of the FET of the present invention show that when the surface charge impurities are 5 × 10 ¹¹ cm ^-2 It can be seen that the result is in good agreement with the theoretical calculation. From this, it can be seen that hydrogen-terminated diamond is used as the semiconductor layer of the present invention and h-BN is used as the gate insulating film 33, and the environment from forming the hydrogen-terminated layer to bonding the h-BN is set to vacuum and atmospheric pressure. The surface charge impurity of the FET of Example 1 fabricated as Ar gas is believed to be approximately 5×10 ¹¹ cm ⁻² . Furthermore, when this surface charge impurity is reduced to 1×10 ¹¹ cm ⁻² , the carrier density range from 2×10 ¹¹ cm ⁻² to 6×10 ¹² cm ⁻² described above is 1×10 ³ cm ^{2 .} It is theoretically calculated that a high mobility of V ⁻¹ s ⁻¹ or more can be obtained.
In the FET of Example 1, in the carrier density range of 10 ¹² to 10 ¹³ cm ^-2 , the mobility is less suppressed by the surface charge existing at the interface between the diamond semiconductor layer 22 and the gate insulator layer 23, and the diamond semiconductor material The high mobility characteristics of the material can be brought out, resulting in high mobility.

FIG. 20 shows the drain voltage dependence of the drain current density of the manufactured MIS type semiconductor device 201. Here, the gate length L _G is 8 μm, the gate width L _W is 0.8 μm, and the thickness of the gate insulating film 33 made of h-BN is 23 nm. The measurement temperature was 300K, and the gate voltage _VG was -10V. Although a slight hysteresis is observed, good p-type FET operation is obtained.

FIG. 21 shows the dependence of the drain current density on the gate voltage V _G when the source-drain voltage V _DS is -10V. The gate length L _G , the gate width L _W , the thickness of the gate insulating film 33 and the measurement temperature are the same as in the case of FIG. 20 . The results show that a high ON/OFF ratio of six orders of magnitude or more is obtained, and that the drain current density when the gate voltage V _G is 0 V is smaller than 4×10 ⁻⁴ mA·mm ⁻¹ . It was confirmed that the manufactured MIS type semiconductor device 201 is an FET with low power consumption.

FIG. 22 shows the dependence of mutual conductance g _m on gate voltage V _G. In this case as well, the gate length L _G , gate width L _W , film thickness of the gate insulating film 33, source-drain voltage V _DS and measurement temperature are the same as in the case of FIG. 21. It can be seen that the manufactured MIS type semiconductor device 201 has good mutual conductance g _m characteristics.

FIG. 23 shows the relationship between gate voltage _VG and drain current _ID . Furthermore, FIG. 24 shows the result of plotting the gate voltage V _G dependence of the square root |I _D | ^1/2 of the drain current based on this measured data. Here, the gate length L _G is 8 μm, the gate width L _W is 0.8 μm, and the thickness of the gate insulating film 33 made of h-BN is 23 nm. The measurement temperature was 300K, and the drain voltage _VD was -10V.
From this result, the threshold voltage V _TH was calculated to be -0.792V, and it was verified that the MIS type semiconductor device 201 manufactured in Example 1 performs normally-off operation.

The present invention provides an MIS type semiconductor device that uses a diamond semiconductor with excellent material properties such as withstand voltage and heat resistance, has high carrier mobility (hole mobility), and consumes little power during standby, contributing to energy saving. becomes possible.
Therefore, the present invention paves the way for semiconductor devices that can handle high power, high frequency, and high temperatures, such as logic circuits that can be used in high-temperature environments, and power devices such as inverters that can be used in high-temperature environments. It is expected that it will be widely used in industry.

11: Carbon 12: Hydrogen 13: Boron 14: Nitrogen 21: Diamond substrate 22: Diamond semiconductor layer 23: Gate insulator layer (gate insulator film)
23a: Insulating film 24: Conductor layer (gate electrode)
25: Insulating film 25a: Insulating film 26: Low resistance layer 27: Gate electrode wiring 28: Source electrode and its electrode wiring 29: Drain electrode and its electrode wiring 31: Diamond substrate 32: Hydrogen termination layer 33: Gate insulating film ( Gate insulator h-BN)
33a: Insulating film 34 _G : Gate electrode (graphite)
35: Conductive film 35a: Conductive film 36: Conductive film 36a: Conductive film 37 _S : Source electrode 37 _D : Drain electrode 42: Low resistance layer 43: Oxygen termination layer 43a: Oxygen termination layer 51, 52, 53: Resist pattern 61: Insulating film (h-BN for element isolation)
62: Conductive film (electrode wiring)
62a: Conductive film 62 _G : Gate electrode wiring (bonding pad wiring)
62 _S : Source electrode wiring (bonding pad wiring)
62 _D : Drain electrode wiring (bonding pad wiring)
71: Boundary between oxygen termination and hydrogen termination regions 101: MIS type semiconductor device 201: MIS type semiconductor device 1001: Processing device 1002: Processing device 1011: Hydrogen termination processing chamber 1012: Gate valve 1013: Turbo pump 1014: Valve 1015: Piping 1016: Scroll pump 1017: Valve 1018: Piping 1019: Valve 1020: Baratron vacuum gauge 1022: Valve 1023: Process gas 1024: Gate valve 1025: Sample transport/temporary storage chamber 1026: Gate valve 1027: Transport intermediate chamber 1028: Flange 1029: Sample transport rod 1031: Bonding processing chamber (glove box)
1032: Partition door 1034: Pass box 1035: Valve 1036: Piping 1037: Scroll pump 1038: Valve 1039: Pressure gauge 1040: Inert gas circulation purifier (Ar gas circulation purifier)
1041: Valve 1042: Piping 1043: Gate valve 1044: Valve 1045: Piping 1052: Ar gas cylinder 1053: Piping 1054: Valve 1055: Valve 1061: Displacement adjustment valve 1062: Piping 1063: Vacuum gauge 1071: Piping 1072: Valve 1073 : Flange 1074: Bellows piping 1075: Turbo exhaust set 1101: Chamber 1102: Angle valve 1103: Turbo pump 1104: Valve 1105: Scroll pump 1106: Valve 1107: Piping 1108: Valve 1109: Bellows piping 1110: Valve 1111: Bellows piping 1112 : Vacuum gauge E1: Hydrogen termination processing section E2: Sample transport section E3: Bonding processing section E4: Vacuum exhaust system

Claims (7)

A p-type MIS semiconductor device comprising a semiconductor layer, an insulator layer, and a conductor layer, the insulator layer being sandwiched between the semiconductor layer and the conductor layer,
The semiconductor layer is made of diamond in which at least a portion of the portion in contact with the insulator layer is hydrogen-terminated,
the threshold voltage V _TH is a negative voltage;
A MIS type semiconductor device , wherein a density of charged impurities existing at an interface between the semiconductor layer and the insulator layer is 0 cm ^-2 or more and 5×10 ¹¹ cm ^-2 or less . The MIS type semiconductor device according to claim 1 , wherein the density of charged impurities present at the interface between the semiconductor layer and the insulator layer is 0 cm ^-2 or more and 1×10 ¹¹ cm ^-2 or less. 3. The MIS type semiconductor device according to claim 1 , wherein said insulating layer is made of boron nitride. 4. The MIS type semiconductor device according to claim 1 , wherein said insulating layer is made of a single crystal of boron nitride. A p-type MIS semiconductor device comprising a semiconductor layer, an insulator layer, and a conductor layer, the insulator layer being sandwiched between the semiconductor layer and the conductor layer,
The semiconductor layer is made of diamond in which at least a portion of the portion in contact with the insulator layer is hydrogen-terminated,
Threshold voltage V _T.H. is a negative voltage,
The mobility in the semiconductor layer is 5×10 ² cm ² V ^-1 s ^-1 More than 3.8×10 ³ cm ² V ^-1 s ^-1 The following MIS type semiconductor device. 6. The MIS type semiconductor device according to claim 1 , wherein said insulating layer is made of hexagonal boron nitride (h-BN). 7. The MIS type semiconductor device according to claim 1, wherein said conductor layer is made of graphite.