Multilayer film structure, method for manufacturing multilayer film structure, and electronic device

Abstract

Provided is a multilayer film structure which improves the mobility of a substrate having a large band gap such as a diamond crystal and not exhibiting mobility. This multilayer film structure is suitable for electronic elements such as transistors and diodes.　A multilayer film structure 10 includes: a substrate layer 1 having a band gap of at least 3.0 electron volts; a first insulating layer 2 disposed on the substrate layer 1; an adsorption layer 3 of any gas molecule selected from the group consisting of nitrogen dioxide (NO2), nitrogen monoxide (NO), sulfur dioxide (SO2), and ozone (O3), the adsorption layer 3 being disposed on the first insulating layer 2; a second insulating layer 4 disposed on the adsorption layer 3; and a gate electrode layer 5 disposed on the second insulating layer 4.

Description

[Technical Field]

[0001] The present invention relates to a multilayer structure, a method for manufacturing the multilayer structure, and an electronic device having the multilayer structure. [Background technology]

[0002] Diamond semiconductors have a band gap of 5.47 electron volts, which is about five times that of silicon semiconductors, and a dielectric strength of over 10 MV / cm, which is more than 33 times that of silicon (0.3 MV / cm), so they are expected to be semiconductor materials for high-efficiency, high-power, high-frequency transistors.In addition to diamond, other materials with large band gaps have also been proposed.

[0003] The inventors have found that by providing a nitrogen dioxide (NO2) adsorption layer on the hydrogen-adsorbed diamond crystal surface, the surface concentration of holes can be reduced to 1x10 14 cm -2 In addition, the mobility in a field effect transistor (FET) is 32 cm 2 However, this mobility is smaller than the inherent mobility of diamond (electron 4500 cm 2 / Vs, Hole 3800cm 2 / Vs). In this way, even semiconductors that have a large band gap and are expected to have superior mobility based on factors such as dielectric strength, are unable to exhibit the inherent properties of the semiconductor material.

[0004] In Non-Patent Document 1, Kakazu reports that NO2 molecules act as acceptor impurities in hydrogen-terminated diamond, generating holes. Regarding the prior art related to Non-Patent Document 1, the electrical conduction of hole carriers in an FET gate structure is explained using Figures 4 and 5. This multilayer film structure 20 (201) uses a diamond crystal 1 as a substrate, on whose surface there is a hydrogen adsorption layer 12, on which an NO2 adsorption layer 3 is formed, an Al2O3 layer 4 is deposited, and finally a gate metal layer 5 is deposited. Non-Patent Documents 2 and 3 also disclose transistors that use diamond.

[0005] Patent Document 1 discloses a diamond field-effect transistor comprising: a diamond substrate; a surface layer formed by terminating the surface of the diamond substrate with hydrogen atoms; a first adsorption layer composed of molecules in the atmosphere formed on the surface layer by exposing the surface layer to the atmosphere; a source electrode and a drain electrode formed spaced apart from each other on the first adsorption layer; a second adsorption layer composed of NO molecules formed so as to cover the entire upper part of the first adsorption layer exposed between the source electrode and the drain electrode; a protective layer formed on the second adsorption layer and composed of an oxygen-containing compound; and a gate electrode formed on the protective layer and spaced apart between the source electrode and the drain electrode. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 5759398 [Non-patent literature]

[0007] [Non-Patent Document 1] M. Kasu, Japanese Journal of Applied Physics 56, 01AA01 (2017) [Non-patent document 2] Hiroshi Kawaharada, "Diamond Two-Dimensional Hole Gas High-Voltage Field-Effect Transistor for Complementary Power Inverters," pp. 37-45, Thin Film and Surface Physics Division, Society of Applied Physics, No. 164 (September 2018). [Non-patent document 3] Hiroshi Kawarada, High-Current Metal Oxide Semiconductor Field-Effect Transistors on H-Terminated Diamond Surfaces and Their High-Frequency Operation, Japanese Journal of Applied Physics 51, 090111 (2012). Summary of the Invention [Problem to be solved by the invention]

[0008] As in Patent Document 1 and Non-Patent Document 1, methods are being considered to express the inherent mobility of substrate materials such as diamond elements. For example, the NO2 molecular acceptors that generate holes become negatively charged ionized acceptors, so holes traveling through the hydrogen adsorption layer and the NO2 adsorption layer between the diamond crystal layer and the Al2O3 film are scattered by the ionized impurity scattering mechanism caused by the NO2 molecular ionized acceptors and the surface scattering mechanism caused by the surface roughness that is unavoidable on the diamond surface, resulting in a mobility of 3800 cm3, which is the inherent mobility of diamond. 2 As a result, the channel resistance was high and the inherent physical properties of diamond could not be exhibited.

[0009] In addition to the above-mentioned methods, other methods have been studied to improve the mobility of diamond elements, but the mobility has not been improved sufficiently. Furthermore, not only diamond, but also substrates with large band gaps and high mobility have not been able to fully utilize their mobility.

[0010] Under these circumstances, an object of the present invention is to provide a multilayer film structure with improved mobility and a method for producing the same. [Means for solving the problem]

[0011] The present inventors have conducted extensive research to solve the above problems and have found that the following inventions meet the above objectives, thereby completing the present invention.

[0012] <1> A multilayer film structure comprising: a substrate layer having a band gap of 3.0 electron volts or more; a first insulating layer disposed on the substrate layer; an adsorption layer of any gas molecule selected from the group consisting of nitrogen dioxide (NO), nitric oxide (NO), sulfur dioxide (SO), and ozone (O) disposed on the first insulating layer; a second insulating layer disposed on the adsorption layer; and a gate electrode layer disposed on the second insulating layer. <2> the substrate layer includes any crystal selected from the group consisting of gallium nitride (GaN), silicon carbide (SiC), gallium oxide (Ga2O3), and diamond, the first insulating layer and the second insulating layer are oxide or fluoride layers, and the gate electrode layer is a metal layer; <1> The multilayer structure according to claim 1. <3> the substrate layer is a layer of diamond crystal having a hydrogen adsorption layer, the first insulating layer is an aluminum oxide (Al2O3) layer having a thickness of 4 to 12 nm, the adsorption layer is a nitrogen dioxide (NO2) adsorption layer, the second insulating layer is an aluminum oxide (Al2O3) layer having a thickness of 4 to 100 nm, and the gate electrode layer is a metal layer, <1> The multilayer structure according to claim 1. <4> The aforementioned <1> ~ <3> 10. An electronic device comprising the multilayer structure according to any one of claims 1 to 9.

[0013] <5> A method for manufacturing a multilayer film structure, comprising: a first deposition step of depositing a material that forms a first insulating layer under a controlled atmosphere on the surface of a substrate layer having a band gap of 3.0 electron volts or more; a formation step of contacting the surface of the first insulating layer with any gas molecule selected from the group consisting of nitrogen dioxide (NO2), nitric oxide (NO), sulfur dioxide (SO2), and ozone (O3) under a controlled atmosphere to form an adsorption layer; and a second deposition step of depositing a material that forms a second insulating layer under a controlled atmosphere on the surface of the adsorption layer. <6> a hydrogen adsorption layer forming step of forming a hydrogen adsorption layer by irradiating a surface of the substrate layer with hydrogen plasma before the first deposition step; <5> The manufacturing method described in <7> Hydrogen adsorption layer The forming step, the first depositing step, the forming step, and the second depositing step are performed in the same processing chamber, and the atmosphere is a vacuum or a nitrogen-substituted atmosphere. <6> The manufacturing method described in <8> The first deposition step is for depositing aluminum oxide (Al2O3) and is performed at a sample temperature of 50 to 300°C; the formation step is for adsorbing nitrogen dioxide (NO2) and, in the formation step, the concentration of NO2 gas is 0.2% or more, the supply time is 3 to 20 minutes, the degree of vacuum is 6.67 kPa to 26.7 kPa, and the adsorption is performed at a sample temperature of 50 to 200°C; the second deposition step is for depositing aluminum oxide (Al2O3) and is performed at a sample temperature of 50 to 200°C; <5> ~ <7> 1. The manufacturing method according to any one of the preceding claims. [Effects of the Invention]

[0014] According to the present invention, a multilayer film structure with improved mobility and a method for manufacturing the same are provided. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a schematic diagram of a multilayer structure of the present invention. [Figure 2]FIG. 2 is another schematic diagram of the multilayer structure of the present invention. [Figure 3] 1A to 1C are schematic diagrams illustrating a manufacturing process for a multilayer structure of the present invention. [Figure 4] FIG. 1 is a schematic diagram of a conventional multilayer film structure. [Figure 5] 1A and 1B are schematic diagrams for explaining a conventional manufacturing process for a multilayer film structure. [Figure 6] FIG. 1 is a schematic diagram for explaining a multilayer film structure according to an embodiment. [Figure 7] 1 is a graph showing the evaluation results of the multilayer film structure according to the example. [Figure 8] 1 is a graph showing the evaluation results of the multilayer film structure according to the example. [Figure 9] 1 is a graph showing the evaluation results of the multilayer film structure according to the example. DETAILED DESCRIPTION OF THE INVENTION

[0016] The following describes in detail an embodiment of the present invention, but the following description of the constituent elements is one example (typical example) of an embodiment of the present invention, and the present invention is not limited to the following content unless the gist of the present invention is changed. Note that when the expression "to" is used in this specification, it is used as an expression that includes the numerical values ​​before and after it.

[0017] [Multilayer film structure of the present invention] The multilayer film structure of the present invention includes a substrate layer having a band gap of 3.0 electron volts or more, a first insulating layer disposed on the substrate layer, an adsorption layer of any gas molecule selected from the group consisting of nitrogen dioxide (NO), nitric oxide (NO), sulfur dioxide (SO), and ozone (O) disposed on the first insulating layer, a second insulating layer disposed on the adsorption layer, and a gate electrode layer disposed on the second insulating layer.

[0018] [Method of manufacturing the multilayer film structure of the present invention] The method for manufacturing a multilayer film structure of the present invention includes a first deposition step of depositing a material that will form a first insulating layer under a controlled atmosphere on the surface of a substrate layer having a band gap of 3.0 electron volts or more; a formation step of contacting the surface of the first insulating layer with any gas molecule selected from the group consisting of nitrogen dioxide (NO), nitric oxide (NO), sulfur dioxide (SO), and ozone (O) under a controlled atmosphere to form an adsorption layer; and a second deposition step of depositing a material that will form a second insulating layer under a controlled atmosphere on the surface of the adsorption layer.

[0019] The multilayer structure of the present invention can exhibit excellent mobility close to the inherent mobility of the substrate layer. The multilayer structure of the present invention can be manufactured by the manufacturing method of the multilayer structure of the present invention, and the corresponding configurations in this application can be used interchangeably.

[0020] In this invention, by providing a new aluminum oxide (Al2O3) layer between the hole transit layer and the nitrogen dioxide (NO2) molecule acceptor layer that generates holes, the hole transit layer and the negatively ionized NO2 molecules are spatially separated, eliminating the ionized impurity scattering and surface scattering mechanisms, and allowing holes to exhibit the inherent high mobility of substrates such as diamond.

[0021] By applying this invention to a diamond substrate, the mobility of a transistor using a conventional diamond substrate is reduced to 30 cm. 2 / Vs is the inherent mobility of diamond, 3800cm 2 / Vs can be increased by more than 100 times. As a result, sheet resistance can be reduced to 1 / 100 or more. The current value can also be increased by more than 100 times. Furthermore, the available power, which is the power that can be controlled by a transistor, can be increased by more than 100 times. This will result in the creation of semiconductor devices that surpass high-power silicon semiconductors.

[0022] [Multilayer film structure 10, 101] 1 is a schematic diagram of a multilayer film structure 10 according to a first embodiment of the present invention. When the multilayer film structure 10 is viewed as the bottom layer, it has, from the bottom, a substrate layer 1, a first insulating layer 2, an adsorption layer 3, a second insulating layer 4, and a gate electrode 5. This multilayer film structure 10 is used in various electronic devices.

[0023] 2 is a schematic diagram of a multilayer structure 101 according to a second embodiment of the present invention. The multilayer structure 101 is similar to the multilayer structure 10, and has a structure in which a hydrogen adsorption layer 12 is formed on the surface of a substrate 1 by performing a hydrogen adsorption treatment.

[0024] [Substrate layer 1] The multilayer film structure 10 (101) has a substrate layer 1. The substrate layer 1 has a band gap of 3.0 electron volts or more. In conventional multilayer film structures, substrates with such large band gaps have not been able to exhibit the mobility expected from the band gap, etc. However, by using such a substrate as the substrate layer of the multilayer film structure 10 (101) of the present invention, excellent mobility can be exhibited.

[0025] The substrate layer 1 may comprise any crystal selected from the group consisting of gallium nitride (GaN), silicon carbide (SiC), gallium oxide (Ga2O3), and diamond, and may consist essentially of any of the foregoing, or a combination of the foregoing with other crystals.

[0026] The band gap of gallium nitride is 3.4 electron volts, that of silicon carbide is 3.2 electron volts, that of gallium oxide is 4.5 to 4.8 electron volts, and that of diamond is 5.5 electron volts. The band gap of the substrate layer 1 is preferably 4.0 electron volts or more, and more preferably 5.0 electron volts or more. Diamond crystal is particularly preferred for the substrate layer 1. Furthermore, for example, KENZAN Diamond (registered trademark) from Adamant Namiki Precision Jewel Co., Ltd. can be preferably used as the diamond crystal.

[0027] [Hydrogen absorption layer 12] As shown in the multilayer film structure 101, the substrate layer 1 preferably has a hydrogen absorbing layer 12. The hydrogen absorbing layer 12 can be formed by irradiating the substrate layer 1 with hydrogen plasma. By providing the hydrogen absorbing layer 12, higher mobility can be achieved. Furthermore, by growing a diamond crystal in a microwave plasma CVD apparatus, a diamond crystal that becomes the substrate layer 1 having the hydrogen absorbing layer can be obtained.

[0028] [First insulating layer 2] The multilayer film structure 10 (101) has a first insulating layer 2. The first insulating layer 2 is disposed on a substrate layer 1 so as to be in contact with the substrate layer 1. If the substrate layer 1 has a hydrogen absorbing layer 12, the first insulating layer 2 is disposed so as to be in contact with the layer on which the hydrogen absorbing layer 12 is provided.

[0029] The first insulating layer, like the second insulating layer, can be an oxide or fluoride layer. These can be oxide or fluoride layers of metal or silicon. Layers made of these materials are called insulating layers because they restrict the movement of electrons and, by increasing their thickness, can essentially eliminate the movement of electrons through the layer. In addition, the insulating layer should have a wider bandgap than the substrate layer.

[0030] Examples of these oxides that can be used include aluminum oxide (Al2O3), magnesium oxide (MgO), hafnium oxide (HfO2), silicon dioxide (SiO2), strontium titanate (SrTiO3), gallium oxide (Ga2O3), lithium niobate (LiNbO3), and lead zirconate titanate (PZT). Examples of fluorides that can be used include calcium fluoride (CaF2) and magnesium fluoride (MgF2). Among these, it is preferable to use one selected from the group consisting of aluminum oxide (Al2O3), magnesium oxide (MgO), hafnium oxide (HfO2), and silicon dioxide (SiO2).

[0031] The first insulating layer 2 is provided between the substrate layer 1 and the adsorption layer 3 to prevent the diffusion of holes and carriers. On the other hand, if the insulating layer is too insulating, high mobility may not be achieved, and the layer may not be usable as a semiconductor. Therefore, the thickness of the first insulating layer is preferably 4 to 12 nm, and more preferably 6 to 10 nm. Furthermore, in view of ease of handling during production, adjustment of film quality, compatibility with the substrate layer 1, etc., it is particularly preferable to use aluminum oxide, and a thickness of approximately 8 nm is particularly preferable. These thicknesses can be measured using a transmission electron microscope (TEM).

[0032] [Adsorption layer 3] The multilayer film structure 10 (101) has an adsorption layer 3. The adsorption layer 3 is disposed on the first insulating layer 2 so as to be in contact with the first insulating layer 2. The adsorption layer 3 is a layer in which any gas molecule selected from the group consisting of nitrogen dioxide (NO), nitric oxide (NO), sulfur dioxide (SO), and ozone (O). As described above, the gas molecule may be one containing any gas molecule selected from the group consisting of NO, NO, SO, and O. In particular, it is preferable that NO be adsorbed.

[0033] [Second insulating layer 4] The multilayer structure 10 (101) has a second insulating layer 4. The second insulating layer 4 is disposed on the adsorption layer 3 so as to be in contact with the adsorption layer 3. The second insulating layer 4 can be made of the same material as the first insulating layer 2.

[0034] The thickness of the second insulating layer 4 is preferably 4 to 100 nm. The upper limit of the thickness of the second insulating layer 4 may be 50 nm or less, 20 nm or less, 12 nm or less, or 10 nm or less. The lower limit of the thickness of the second insulating layer 4 may be 6 nm or more.

[0035] [Gate electrode 5] The multilayer film structure 10 (101) has a gate electrode 5. The gate electrode 5 is disposed on the second insulating layer 4 so as to be in contact with the second insulating layer 4. The gate electrode is preferably a metal layer. The metal layer can be made of gold (Au), a laminated film of gold and titanium (Ti / Au from the bottom up), or a laminated film of gold, titanium, and aluminum (Al / Ti / Au from the bottom up).

[0036] As in the multilayer film structure 102 (see FIG. 3), it may have other structures such as a source electrode 8 and a drain electrode 9.

[0037] The multilayer film structure 10 (101, 102) can be used in electronic devices that use electrical conduction, such as transistors, diodes, and MEMS.

[0038] [Manufacturing method flow] 3 is a schematic diagram for explaining an example of the manufacturing process of the multilayer structure of the present invention. The multilayer structure 102 can be manufactured by steps 1 to 6. FIG. 3(a) Step 1: First, produce a substrate layer 1. For example, a substrate layer of diamond crystal can be grown in a CVD apparatus. 3(b), Step 2: Next, a hydrogen absorbing layer 12 is provided on the substrate layer 1. The hydrogen absorbing layer 12 can be formed by irradiating the substrate layer 1 with hydrogen plasma. FIG. 3(c) Step 3: Next, a source electrode 8 is provided at one end of the substrate layer 1, and a drain electrode 9 is provided at the other end, spaced apart from the source electrode 8. 3(d) Step 4: Next, a first insulating layer 2 is provided between the source electrode 8 and the drain electrode 9 so as to be in contact with the hydrogen absorbing layer 12 of the substrate layer 1. The first insulating layer 2 can be provided by a first deposition step in which a material such as aluminum oxide (Al2O3) is deposited. 3(e) Step 5: Next, a formation step is performed in which any gas molecule selected from the group consisting of nitrogen dioxide (NO), nitric oxide (NO), sulfur dioxide (SO), and ozone (O) is brought into contact with the first insulating layer 2 to form an adsorption layer 3. Furthermore, a second deposition step is performed in which a material that will form the second insulating layer 4 is deposited on the adsorption layer 3. FIG. 3(f) Step 6: Then, a gate electrode 5 is provided on the second insulating layer 4, whereby a multilayer film structure 102 can be obtained.

[0039] [Hydrogen absorption layer formation process] The hydrogen absorption layer forming step is a step of forming a hydrogen absorption layer on the surface of the substrate layer 1 having a band gap of 3.0 electron volts or more. The hydrogen absorption layer can be formed, for example, by irradiating the substrate layer 1 with hydrogen plasma.

[0040] [First deposition process] The first deposition step is preferably a step of depositing a material that forms a first insulating layer. The first deposition step is a step of depositing aluminum oxide (Al2O3), and the deposition is preferably performed at a sample temperature of 50 to 300°C. The temperature may also be 100 to 250°C.

[0041] [Formation process] The forming step is preferably a step of contacting the surface of the first insulating layer with any one of gas molecules selected from the group consisting of nitrogen dioxide (NO2), nitric oxide (NO), sulfur dioxide (SO2), and ozone (O3) to form an adsorption layer. The forming step is for adsorbing gas molecules, and the concentration of the gas molecule gas is preferably 0.2% or more. The supply time of the gas molecules is preferably 3 to 20 minutes. Furthermore, when the step is performed under vacuum conditions, the degree of vacuum is preferably 6.67 kPa to 26.7 kPa (50 to 200 torr). The degree of vacuum is particularly preferably 14.7 kPa to 18.7 kPa (110 to 140 torr). Furthermore, to stabilize the adsorbed gas molecules, the sample temperature is preferably 50 to 200°C.

[0042] [Second deposition process] The second deposition step is a step of depositing a material that forms a second insulating layer on the surface of the adsorption layer. The second deposition step is a step of depositing aluminum oxide (Al2O3), and the deposition is preferably performed at a sample temperature of 50 to 200°C.

[0043] The hydrogen absorbing layer forming step, first deposition step, forming step, and second deposition step are preferably performed in the same processing chamber under a controlled atmosphere. The controlled atmosphere can be substituted with nitrogen or under vacuum. While it has been considered preferable to perform the deposition step in the air, the present invention allows the deposition step to be performed under nitrogen or under vacuum. Therefore, the subsequent deposition step, forming step, and so on can be performed in the same processing chamber as the hydrogen absorbing layer forming step, which facilitates the management of the manufacturing process and enables the consistent production of high-quality products. [Example]

[0044] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples as long as the gist of the present invention is not changed.

[0045] [Example 1] The following steps will be described as an example of fabricating a multilayer structure corresponding to the multilayer structure 102 in FIG. (1) Kenzan Diamond (registered trademark) manufactured by Adamant Namiki Precision Jewel Co., Ltd. was used as the substrate layer 1. (2) The substrate layer 1 was irradiated with hydrogen plasma (represented by H) in the reactor of a microwave plasma CVD apparatus to form a hydrogen absorption layer 12. The hydrogen absorption layer 12 was generated by leaving the substrate 1 for 10 minutes under the conditions of a microwave frequency of 2.45 GHz, an output of 750 W, a reaction pressure of 50 Torr (6.67 kPa), and a hydrogen supply rate of 300 ccm. (3) Next, a source electrode 8 and a drain electrode 9 were formed by vacuum deposition. (4) Next, the sample was subjected to atomic layer deposition (ALD) in a vacuum by alternately supplying trimethylaluminum and H2O to deposit an aluminum oxide layer (Al2O3 film) as a first insulating layer 2. (5) Next, NO2 with a concentration of 2% was supplied to form an NO2 adsorption layer 3. (6) Next, an aluminum oxide layer (Al2O3 film) was deposited as a second insulating layer 4 again using the ALD method. (7) Finally, an Au film that will become the gate electrode layer 5 is vapor deposited.

[0046] An outline of a manufacturing example according to Example 1 is shown in Figure 6. In describing the multilayer film structure in Figure 6, "Al2O3-8nm@230°C" means that an 8-nm aluminum oxide layer was deposited at 230°C. "NO2@80°C" means that NO2 gas was adsorbed at 80°C. "Al2O3-8nm@80°C" means that an 8-nm aluminum oxide layer was deposited at 80°C.

[0047] Figures 7 and 8 show the sheet resistance (kΩ / sq.) and drain voltage (V DS (V)) vs. drain current ((I DS The results of evaluating the gate voltage dependence using the MOSFET current (mA / mm) are shown below. These measurements were performed using a Keysight Technologies B1505A Power Device Analyzer / Curve Tracer.

[0048] Figure 7 shows the results of examining the thickness and processing temperature of the aluminum oxide layer used as the first insulating layer. Note that in the examinations of Figures 7 and 8, the evaluation was performed using the configuration shown in Figure 6, except for the conditions that were changed. The first insulating layer had the lowest sheet resistance, especially when it was 8 nm thick.

[0049] Figure 8 shows the results of examining the processing temperature in the formation process of the NO adsorption layer. When the temperature for forming the NO adsorption layer was set to approximately 80°C, the sheet resistance was lower. In Figure 8, the notations (80°C, 80°C), (230°C, 80°C), and (230°C, 230°C) in the graph refer to the test conditions at each measurement point. The left side of the parentheses indicates the sample temperature during deposition of the first aluminum oxide layer (first Al2O3), and the right side of the parentheses indicates the sample temperature during deposition of the second aluminum oxide layer (second Al2O3). For example, (80°C, 80°C) indicates that the sample temperature during deposition of the first aluminum oxide layer was 80°C, and the sample temperature during deposition of the second aluminum oxide layer was 80°C.

[0050] Figure 9 shows the results of evaluating the gate voltage dependence of the multilayer structure shown on the left side of Figure 9. In particular, this is an example where the deposition conditions for the first insulating layer were set to temperatures (X°C) of 80°C, 230°C, and 330°C. The results of measuring the maximum drain current of the FETs with multilayer structures manufactured at these manufacturing temperatures are shown on the right side of Figure 9. [Industrial Applicability]

[0051] The multilayer film structure of the present invention can be used in electronic devices such as transistors and diodes, and is therefore industrially useful. [Explanation of symbols]

[0052] 1. Substrate Layer 10, 101, 102, 20, 201 Multilayer film structure 12 Hydrogen adsorption layer 2. First insulating layer 3 Adsorption layer 4 Second insulating layer 5. Gate electrode 8 Source Electrode 9 Drain electrode

Claims

1. a substrate layer having a band gap of 3.0 electron volts or more; a first insulating layer disposed on the substrate layer; Nitrogen dioxide (NO) disposed on the first insulating layer 2 ), nitric oxide (NO), sulfur dioxide (SO 2 ), and ozone (O 3 an adsorption layer of any gas molecule selected from the group consisting of a second insulating layer disposed on the adsorption layer; a gate electrode layer disposed on the second insulating layer.

2. The substrate layer may be made of gallium nitride (GaN), silicon carbide (SiC), gallium oxide (Ga 2 O 3 ), and diamond, the first insulating layer and the second insulating layer are oxide or fluoride layers; 2. The multilayer structure according to claim 1, wherein the gate electrode layer is a metal layer.

3. the substrate layer is a layer of diamond crystal having a hydrogen adsorption layer; The first insulating layer is made of aluminum oxide (Al 2 O 3 ) layer, The adsorption layer is formed by dissolving nitrogen dioxide (NO 2 ) adsorption layer, The second insulating layer is made of aluminum oxide (Al 2 O 3 ) layer, 2. The multilayer structure according to claim 1, wherein the gate electrode layer is a metal layer.

4. An electronic device comprising the multilayer structure according to any one of claims 1 to 3.

5. a first deposition step of depositing a material forming a first insulating layer on a surface of a substrate layer having a bandgap of 3.0 electron volts or more under a controlled atmosphere; The surface of the first insulating layer is coated with nitrogen dioxide (NO 2 ), nitric oxide (NO), sulfur dioxide (SO 2 ), and ozone (O 3 a forming step of contacting the surface of the substrate with any gas molecule selected from the group consisting of: a second deposition step of depositing a material that forms a second insulating layer on the surface of the adsorption layer under a controlled atmosphere.

6. 6. The manufacturing method according to claim 5, further comprising, before the first deposition step, a hydrogen absorption layer forming step of forming a hydrogen absorption layer by irradiating the surface of the substrate layer with hydrogen plasma.

7. 7. The manufacturing method according to claim 6, wherein the hydrogen absorbing layer forming step, the first depositing step, the forming step, and the second depositing step are performed in the same processing chamber, and the atmosphere is a vacuum or a nitrogen-substituted atmosphere.

8. The first deposition step is performed by depositing aluminum oxide (Al 2 O 3 ) is deposited at a sample temperature of 50 to 300°C; The forming step comprises: 2 ) is adsorbed, and in the forming step, NO 2 The gas concentration is 0.2% or more, the supply time is 3 to 20 minutes, the degree of vacuum is 6.67 kPa to 26.7 kPa, and the sample temperature is 50 to 200°C, and the gas is adsorbed. The second deposition step is performed by depositing aluminum oxide (Al 2 O 3 8. The method according to claim 5, wherein the deposition is performed at a sample temperature of 50 to 200°C.

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