Crystalline oxide film, stacked structure, semiconductor device, and method for manufacturing crystalline oxide film

Abstract

This crystalline oxide film includes gallium as a main component, and is characterized in that when the crystalline oxide film is examined by X-ray diffraction with CuKα line being caused to enter and when the angle φ around the φ axis, which is orthogonal to the surface of the crystalline oxide film, is a value which, in ω-2θ examination, results in a maximum peak derived from the crystalline oxide film, then the reflection outputs in ω and 2θ scanning have maximal values when 16.20°<2θ<39.90° and 20.30°<ω<32.20° and that the ω and θ at which the reflection outputs are maximal satisfy 40.10°<ω+θ<40.40°. Due to these features, the crystalline oxide film has excellent semiconductor characteristics, especially withstand voltage. Also provided are a multilayer structure, a semiconductor device, and a method for producing the crystalline oxide film.

Description

[Technical Field]

[0001] The present invention relates to a crystalline oxide film, a stacked structure, a semiconductor device, and a method for producing a crystalline oxide film. [Background technology]

[0002] As a next-generation switching element that can achieve high voltage resistance, low loss, and high heat resistance, semiconductor devices using gallium oxide (Ga2O3), which has a large band gap, are attracting attention, and are expected to be applied to power semiconductor devices such as inverters. The band gap of gallium oxide can be controlled by mixing indium and aluminum, individually or in combination, to form a mixed crystal. In particular, In X’ Al Y’ Ga Z’ The InAlGaO-based semiconductor, represented by O3 (0≦X'≦2, 0≦Y'≦2, 0≦Z'≦2, X'+Y'+Z'=1.5-2.5), is an extremely attractive material. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-028480 [Patent Document 2] Japanese Patent Application Laid-Open No. 2013-058637 [Patent Document 3] International Publication No. 2016 / 013554 [Patent Document 4] JP 2018-129500 A Summary of the Invention [Problem to be solved by the invention]

[0004] Patent Document 1 describes a highly crystalline conductive α-Ga2O3 thin film doped with a dopant (tetravalent tin). However, the thin film described in Patent Document 1 cannot maintain sufficient pressure resistance, contains a large amount of carbon impurities, and has unsatisfactory semiconducting properties, including conductivity, making it difficult to use in semiconductor devices.

[0005] Patent Document 2 describes the formation of a p-type α-(Al x Ga 1-x A Ga2O3-based semiconductor device on which a Ga2O3 single crystal film is formed is described in Patent Document 2. However, the semiconductor device described in Patent Document 2 has many limitations in terms of application to semiconductor devices, as α-Al2O3 is an insulator and there are problems with the crystal quality. Furthermore, the MBE method requires ion implantation and high-temperature heat treatment to obtain a p-type semiconductor, which makes it difficult to obtain p-type α-Al2O3 itself, and in fact makes it difficult to realize the semiconductor device described in Patent Document 2.

[0006] In response to these circumstances, Patent Document 3 fabricates an SBD (Schottky barrier diode) using α-Ga2O3 with a film thickness of 11.9 μm, achieving a breakdown voltage of over 300 V. However, although the SBD manufacturing method described in Patent Document 3 is a relatively simple method, it requires the film thickness to be thicker than necessary, and there are also issues with reproducibility (i.e., yield).

[0007] In Patent Document 4, an SBD with a surface area of ​​1 mm square was fabricated, and a breakdown voltage of over 855 V was achieved. However, the SBD described in Patent Document 4 required the use of bromideuteric acid to fabricate the α-Ga2O3 semiconductor layer, which posed a problem in that it was not cost-effective for industrial use.

[0008] The present invention aims to provide a crystalline oxide film, a stacked structure, and a semiconductor device that have excellent semiconductor properties, particularly excellent pressure resistance, while avoiding the above-mentioned problems. Another object of the present invention is to provide a method for producing a crystalline oxide film that can produce a crystalline oxide film that has excellent semiconductor properties, particularly excellent pressure resistance. [Means for solving the problem]

[0009] In order to solve the above problems, the present invention provides a crystalline oxide film containing gallium as a main component, wherein, when CuKα rays are incident on the crystalline oxide film and X-ray diffraction is performed, the angle φ around the φ axis perpendicular to the surface of the crystalline oxide film is φ at which the peak derived from the crystalline oxide film in ω-2θ measurement is maximized, and the reflected output when ω and 2θ are scanned has maximum points at 16.20°<2θ<39.90° and 20.30°<ω<32.20°, and the ω and θ at which the reflected output is maximized are 40.10°<ω+θ<40.40°.

[0010] The present invention also provides a crystalline oxide film containing gallium as a main component, wherein, when CuKα rays are incident on the crystalline oxide film and X-ray diffraction is performed, the angle φ around the φ axis perpendicular to the surface of the crystalline oxide film is φ at which the peak derived from the crystalline oxide film in ω-2θ measurement is maximized, and the reflected output when ω and 2θ are scanned has maximum points at 26.20°<2θ<49.90° and 25.30°<ω<37.20°, and the ω and θ at which the reflected output is maximized are 50.10°<ω+θ<50.40°.

[0011] The present invention also provides a crystalline oxide film containing gallium as a main component, wherein, when CuKα rays are incident on the crystalline oxide film and X-ray diffraction is performed, the angle φ around the φ axis perpendicular to the surface of the crystalline oxide film is φ at which the peak derived from the crystalline oxide film in ω-2θ measurement is maximized, and the reflected output when ω and 2θ are scanned has maximum points at 12.00°<2θ<35.70° and 18.20°<ω<30.10°, and the ω and θ at which the reflected output is maximized are 35.90°<ω+θ<36.20°.

[0012] The present invention also provides a crystalline oxide film containing gallium as a main component, wherein, when CuKα rays are incident on the crystalline oxide film and X-ray diffraction is performed, the angle φ around the φ axis perpendicular to the surface of the crystalline oxide film is φ at which the peak derived from the crystalline oxide film in ω-2θ measurement is maximized, and the reflected output when ω and 2θ are scanned has maximum points at 40.80°<2θ<64.50° and 32.60°<ω<44.50°, and the ω and θ at which the reflected output is maximized are 64.70°<ω+θ<65.00°.

[0013] The crystalline oxide film described above can be obtained with a high yield by a simple process, has excellent crystallinity, and when applied to a semiconductor device, has excellent semiconductor properties, particularly excellent pressure resistance, and also has excellent surface smoothness.

[0014] In the present invention, the surface area of ​​the crystalline oxide film is 100 mm 2 It is preferable that the diameter is 50 mm or more.

[0015] This makes it possible to obtain a crystalline oxide film with excellent crystallinity over a large area.

[0016] The present invention also provides a layered structure including at least a base substrate and the above-described crystalline oxide film.

[0017] This provides a laminated structure that has excellent crystallinity and exhibits excellent semiconductor properties, particularly excellent pressure resistance, when applied to a semiconductor device, and also has excellent surface smoothness.

[0018] The present invention also provides a semiconductor device that includes the above-described crystalline oxide film.

[0019] This provides a semiconductor device with excellent semiconductor characteristics, particularly excellent voltage resistance.

[0020] Furthermore, in the present invention, there is provided a method for producing a crystalline oxide film containing gallium as a main component, wherein when CuKα rays are incident and X-ray diffraction is performed, an angle φ around a φ axis perpendicular to the surface of a base substrate is measured as follows by ω-2θ measurement: On the base substrate Origin do The present invention provides a method for producing a crystalline oxide film, characterized in that the reflected output when scanning ω and 2θ at φ where the peak is maximum has maximum points at 17.70°<2θ<41.40° and 21.00°<ω<32.90°, and the ω and θ where the reflected output is maximum are such that 41.60°<ω+θ<41.90°.

[0021] In addition, the present invention provides a method for producing a crystalline oxide film containing gallium as a main component, wherein when CuKα rays are incident on the film and X-ray diffraction is performed, the angle φ around the φ axis perpendicular to the surface of the base substrate is determined by ω-2θ measurement. On the base substrate Origin do The present invention provides a method for producing a crystalline oxide film, characterized in that the reflected output when scanning ω and 2θ at φ where the peak is maximum has maximum points at 28.60°<2θ<52.30° and 26.50°<ω<38.40°, and the ω and θ where the reflected output is maximum are such that 52.50°<ω+θ<52.80°.

[0022] Furthermore, in the present invention, there is provided a method for producing a crystalline oxide film containing gallium as a main component, wherein when CuKα rays are incident and X-ray diffraction is performed, an angle φ around a φ axis perpendicular to the surface of a base substrate is measured as follows by ω-2θ measurement: On the base substrate Origin do The present invention provides a method for producing a crystalline oxide film, characterized in that the reflected output when scanning ω and 2θ at φ where the peak is maximum has maximum points at 13.80°<2θ<37.50° and 19.10°<ω<31.00°, and the ω and θ where the reflected output is maximum are 37.70°<ω+θ<38.00°.

[0023] In addition, the present invention provides a method for producing a crystalline oxide film containing gallium as a main component, wherein when CuKα rays are incident on the film and X-ray diffraction is performed, the angle φ around the φ axis perpendicular to the surface of the base substrate is determined by ω-2θ measurement. On the base substrate Origin do The present invention provides a method for producing a crystalline oxide film, characterized in that the reflected output when scanning ω and 2θ at φ where the peak is maximum has a maximum point at 44.30°<2θ<68.00° and 34.30°<ω<46.20°, and the ω and θ where the reflected output is maximum are such that 68.20°<ω+θ<68.50°.

[0024] The above-described method for producing a crystalline oxide film can produce a crystalline oxide film with a high yield through a simple process. Furthermore, the method can produce a crystalline oxide film with excellent crystallinity and excellent semiconductor properties, particularly excellent pressure resistance, when applied to a semiconductor device. Furthermore, the method can produce a crystalline oxide film with excellent surface smoothness. [Effects of the Invention]

[0025] As described above, the crystalline oxide film of the present invention has excellent crystallinity and exhibits excellent semiconductor properties, particularly excellent pressure resistance, when applied to a semiconductor device. It also has excellent surface smoothness. Furthermore, the layered structure of the present invention provides a layered structure that has excellent crystallinity and exhibits excellent semiconductor properties, particularly excellent pressure resistance, when applied to a semiconductor device. It also has excellent film surface smoothness. Furthermore, leakage current is suppressed. Furthermore, the method for producing a crystalline oxide film of the present invention can provide a crystalline oxide film that has excellent crystallinity, excellent semiconductor properties when applied to a semiconductor device, particularly excellent pressure resistance, and excellent surface smoothness. [Brief explanation of the drawings]

[0026] [Figure 1] 1 is a schematic diagram showing an example of a semiconductor device using a stacked structure according to the present invention; [Figure 2]1 is a schematic diagram showing an example of a film-forming apparatus (mist CVD apparatus) suitably used for forming a film of a laminated structure according to the present invention. [Figure 3] FIG. 2 is a diagram illustrating an example of a mist-generating unit used in the present invention. [Figure 4] FIG. 1 is a conceptual diagram of an X-ray diffraction method according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0027] As described above, there has been a need to provide a crystalline oxide film that has excellent pressure resistance.

[0028] As a result of extensive research into the above-mentioned problems, the inventors have discovered that when CuKα rays are incident on a crystalline oxide film and X-ray diffraction is performed, the reflected output when scanning φ, ω, and 2θ has maxima at 16.20°<2θ<39.90° and 20.30°<ω<32.20°, and the ω and θ at which the reflected output is maximized are 40.10°<ω+θ<40.40°, and the film contains gallium as a main component, can be obtained with a high yield using a simple process, has excellent crystallinity, and exhibits excellent semiconductor properties, particularly high pressure resistance, when applied to a semiconductor device, and have completed the present invention.

[0029] That is, the present invention provides a crystalline oxide film containing gallium as a main component, wherein when CuKα rays are incident on the crystalline oxide film and X-ray diffraction is performed, the angle φ around the φ axis perpendicular to the surface of the crystalline oxide film is φ at which the peak derived from the crystalline oxide film in ω-2θ measurement is maximized, and the reflected output when ω and 2θ are scanned has maximum points at 16.20°<2θ<39.90° and 20.30°<ω<32.20°, and the ω and θ at which the reflected output is maximized are 40.10°<ω+θ<40.40°.

[0030] Furthermore, as a result of extensive research into the above-mentioned problems, the inventors have discovered that when CuKα rays are incident on a crystalline oxide film and X-ray diffraction is performed, the reflected output when φ, ω, and 2θ are scanned has maxima at 26.20°<2θ<49.90° and 25.30°<ω<37.20°, and the ω and θ at which the reflected output is maximized are 50.10°<ω+θ<50.40°, and the film contains gallium as a main component, can be obtained with a high yield using a simple process, has excellent crystallinity, and exhibits excellent semiconductor properties, particularly high voltage resistance, when applied to a semiconductor device, and have completed the present invention.

[0031] That is, the present invention provides a crystalline oxide film containing gallium as a main component, wherein when CuKα rays are incident on the crystalline oxide film and X-ray diffraction is performed, the angle φ about the φ axis perpendicular to the surface of the crystalline oxide film is φ at which the peak derived from the crystalline oxide film in ω-2θ measurement is maximized, and the reflected output when ω and 2θ are scanned has maximum points at 26.20°<2θ<49.90° and 25.30°<ω<37.20°, and the ω and θ at which the reflected output is maximized are 50.10°<ω+θ<50.40°.

[0032] Furthermore, as a result of extensive research into the above-mentioned problems, the inventors have discovered that when CuKα rays are incident on a crystalline oxide film and X-ray diffraction is performed, the reflected output when φ, ω, and 2θ are scanned has maxima at 12.00°<2θ<35.70° and 18.20°<ω<30.10°, and the ω and θ at which the reflected output is maximized are 35.90°<ω+θ<36.20°, and the film contains gallium as a main component, can be obtained with a high yield using a simple process, has excellent crystallinity, and exhibits excellent semiconductor properties, particularly high voltage resistance, when applied to a semiconductor device, and have completed the present invention.

[0033] That is, the present invention provides a crystalline oxide film containing gallium as a main component, wherein, when CuKα rays are incident on the crystalline oxide film and X-ray diffraction is performed, the angle φ around the φ axis perpendicular to the surface of the crystalline oxide film is φ at which the peak derived from the crystalline oxide film in ω-2θ measurement is maximized, and the reflected output when ω and 2θ are scanned has maximum points at 12.00°<2θ<35.70° and 18.20°<ω<30.10°, and the ω and θ at which the reflected output is maximized are 35.90°<ω+θ<36.20°.

[0034] Furthermore, as a result of extensive research into the above-mentioned problems, the inventors have discovered that when CuKα rays are incident on a crystalline oxide film and X-ray diffraction is performed, the reflected output when scanning φ, ω, and 2θ has maxima at 40.80°<2θ<64.50° and 32.60°<ω<44.50°, and the ω and θ at which the reflected output is maximized are 64.70°<ω+θ<65.00°, and the film contains gallium as a main component, and can be obtained with a high yield using a simple process.The film also has excellent crystallinity and, when applied to a semiconductor device, exhibits excellent semiconductor properties, particularly excellent pressure resistance, and has been found to have been completed based on this discovery.

[0035] That is, the present invention provides a crystalline oxide film containing gallium as a main component, wherein when CuKα rays are incident on the crystalline oxide film and X-ray diffraction is performed, the angle φ around the φ axis perpendicular to the surface of the crystalline oxide film is φ at which the peak derived from the crystalline oxide film in ω-2θ measurement is maximized, and the reflected output when ω and 2θ are scanned has maximum points at 40.80°<2θ<64.50° and 32.60°<ω<44.50°, and the ω and θ at which the reflected output is maximized are 64.70°<ω+θ<65.00°.

[0036] Furthermore, as a result of extensive research into the above-mentioned problems, the inventors have found that when CuKα rays are incident on a sapphire substrate as a base substrate, the reflected output when scanning φ, ω, and 2θ has a maximum at 17.70°<2θ<41.40° and 21.00°<ω<32.90°, and that the ω and θ at which the reflected output is maximized are 41.60°<ω+θ<41.90°. The present inventors have found that a crystalline oxide film can be produced with a high yield by a simple process, and that the reflected output when subjected to a scanning electron microscope has maximum points at 16.20°<2θ<39.90° and 20.30°<ω<32.20°, and that the ω and θ at which the reflected output is maximized are 40.10°<ω+θ<40.40°. The obtained crystalline oxide film has excellent crystallinity and, when applied to a semiconductor device, exhibits excellent semiconductor properties, particularly excellent pressure resistance, and have been completed based on this finding.

[0037] That is, the present invention is a method for producing a crystalline oxide film containing gallium as a main component, characterized in that the crystalline oxide film is formed on a sapphire substrate as a base substrate, which, when CuKα rays are incident and X-ray diffraction is performed, has a reflection output when ω and 2θ are scanned at an angle φ about a φ axis perpendicular to the surface at which the peak derived from the base substrate in ω-2θ measurement is maximized, and has maximum points at 17.70°<2θ<41.40° and 21.00°<ω<32.90°, and the ω and θ at which the reflection output is maximized are 41.60°<ω+θ<41.90°.

[0038] Furthermore, as a result of extensive research into the above-mentioned problems, the inventors have found that when CuKα rays are incident on a sapphire substrate as a base substrate, the reflected output when scanning φ, ω, and 2θ has a maximum at 28.60°<2θ<52.30° and 26.50°<ω<38.40°, and that the ω and θ at which the reflected output is maximized are 52.50°<ω+θ<52.80°. The present inventors have found that a crystalline oxide film can be produced with a high yield by a simple process, and that the reflected output when subjected to a scanning electron microscope has maximum points at 26.20°<2θ<49.90° and 25.30°<ω<37.20°, and that the ω and θ at which the reflected output is maximized are 50.10°<ω+θ<50.40°. The obtained crystalline oxide film has excellent crystallinity and, when applied to a semiconductor device, exhibits excellent semiconductor properties, particularly excellent pressure resistance, and have been completed based on this finding.

[0039] That is, the present invention is a method for producing a crystalline oxide film containing gallium as a main component, characterized in that the crystalline oxide film is formed on a sapphire substrate as a base substrate, which, when CuKα rays are incident and X-ray diffraction is performed, has a reflection output when ω and 2θ are scanned at an angle φ about a φ axis perpendicular to the surface at which the peak derived from the base substrate in ω-2θ measurement is maximized, and has maximum points at 28.60°<2θ<52.30° and 26.50°<ω<38.40°, and has an ω, θ angle at which the reflection output is maximized being 52.50°<ω+θ<52.80°.

[0040] Furthermore, as a result of extensive research into the above-mentioned problems, the inventors have found that when CuKα rays are incident on a sapphire substrate as a base substrate, the reflected output when scanning φ, ω, and 2θ has a maximum at 13.80°<2θ<37.50° and 19.10°<ω<31.00°, and that the ω and θ at which the reflected output is maximized are 37.70°<ω+θ<38.00°. The present inventors have found that a crystalline oxide film can be produced with a high yield by a simple process, in which the reflected output has maximum points when 12.00°<2θ<35.70° and 18.20°<ω<30.10°, and the ω and θ at which the reflected output is maximized are 35.90°<ω+θ<36.20°, and that the obtained crystalline oxide film has excellent crystallinity and, when applied to a semiconductor device, exhibits excellent semiconductor properties, particularly excellent pressure resistance, and have completed the present invention.

[0041] That is, the present invention is a method for producing a crystalline oxide film containing gallium as a main component, characterized in that the crystalline oxide film is formed on a sapphire substrate as a base substrate, which, when CuKα rays are incident and X-ray diffraction is performed, has a reflection output when ω and 2θ are scanned at an angle φ about a φ axis perpendicular to the surface at which the peak derived from the base substrate in ω-2θ measurement is maximized, and has maximum points at 13.80°<2θ<37.50° and 19.10°<ω<31.00°, and has an ω, θ angle at which the reflection output is maximized being 37.70°<ω+θ<38.00°.

[0042] Furthermore, as a result of extensive research into the above-mentioned problems, the inventors have found that when CuKα rays are incident on a sapphire substrate as a base substrate, the reflected output when scanning φ, ω, and 2θ has a maximum at 44.30°<2θ<68.00° and 34.30°<ω<46.20°, and that the ω and θ at which the reflected output is maximized are 68.20°<ω+θ<68.50°. The present inventors have found that a crystalline oxide film can be produced with a high yield by a simple process, in which the reflected output has maximum points at 40.80°<2θ<64.50° and 32.60°<ω<44.50°, and the ω and θ at which the reflected output is maximized are 64.70°<ω+θ<65.00°, and that the obtained crystalline oxide film has excellent crystallinity and, when applied to a semiconductor device, exhibits excellent semiconductor properties, particularly excellent pressure resistance, and have completed the present invention.

[0043] That is, the present invention is a method for producing a crystalline oxide film containing gallium as a main component, characterized in that the crystalline oxide film is formed on a sapphire substrate as a base substrate, which, when CuKα rays are incident and X-ray diffraction is performed, has a reflection output when ω and 2θ are scanned at an angle φ about a φ axis perpendicular to the surface at which the peak derived from the base substrate in ω-2θ measurement is maximized, and has maximum points at 44.30°<2θ<68.00° and 34.30°<ω<46.20°, and has an ω, θ angle of 68.20°<ω+θ<68.50° relative to the ω, θ at which the reflection output is maximized.

[0044] The present invention will be described in detail below, but the present invention is not limited thereto.

[0045] (crystalline oxide film) When the crystalline oxide film according to the first invention of the present application is subjected to X-ray diffraction with incident CuKα radiation, the reflected output when scanning φ, ω, and 2θ has maxima at 16.20°<2θ<39.90° and 20.30°<ω<32.20°.

[0046] A conceptual diagram of X-ray diffraction according to the present invention is shown in Figure 4. An X-ray source 402 generates CuKα radiation (wavelength 1.5418 Å). X-rays are incident on the sample surface of a sample 401 at an angle ω through an incident optical element 403, and the reflected X-rays are detected by a detector 405 at an angle θ relative to the sample surface through a light-receiving optical element 404 (the control parameter usually used is 2θ, twice the angle θ). A φ-axis 411 is perpendicular to the sample surface, and the sample is rotated by an angle φ around the φ-axis 411 while keeping the sample surface horizontal. If the instrument does not have a sample rotation mechanism, it is acceptable to rotate the sample manually as needed.

[0047] In the first invention of the present application, first, a conventional ω-2θ measurement (scanning ω and 2θ simultaneously with ω = θ) is performed with the slit of the detector 405 widened. While capturing the peak derived from the crystalline oxide film, φ is scanned from 0 to 90° to find the φ at which the detected intensity is maximized. Next, φ is fixed at the angle at which the detected intensity is maximized, and the slit of the detector 405 is narrowed, and 2θ is scanned independently in a range of, for example, 15° to 45°, and ω is scanned in a range of, for example, 15° to 35°. Next, after rotating φ by 180° from the angle at which the detected intensity is maximized, 2θ and ω are scanned again. The crystalline oxide film is characterized in that the maximum reflected intensity (reflected output) has maximal points at 16.20°<2θ<39.90° and 20.30°<ω<32.20°, and the ω and θ at which the reflected output is maximized are 40.10°<ω+θ<40.40°.

[0048] The second invention of the present application is a crystalline oxide film characterized in that, when measurements similar to those described above are performed, the maximum reflection intensity (reflection output) has maximal points at 26.20°<2θ<49.90° and 25.30°<ω<37.20°, and the ω and θ at which the reflection output is maximized are 50.10°<ω+θ<50.40°.

[0049] The third invention of the present application is a crystalline oxide film characterized in that, when measurements similar to those described above are performed, the maximum reflection intensity (reflection output) has maximal points at 12.00°<2θ<35.70° and 18.20°<ω<30.10°, and the ω and θ at which the reflection output is maximized are 35.90°<ω+θ<36.20°.

[0050] The fourth invention of the present application is a crystalline oxide film characterized in that, when measurements similar to those described above are performed, the maximum reflection intensity (reflection output) has maximum points at 40.80°<2θ<64.50° and 32.60°<ω<44.50°, and the ω and θ at which the reflection output is maximum are 64.70°<ω+θ<65.00°.

[0051] The absence of θ=ω in any of the crystalline oxide films suggests that the film surface and the crystal plane are not parallel. This reduces the occurrence of crystal defects that penetrate perpendicularly to the film surface, leading to superior crystallinity and superior voltage resistance when applied to semiconductor devices.

[0052] If ω, 2θ, and ω+θ are outside the above ranges, the breakdown voltage yield will be low, which is undesirable.

[0053] The crystal structure of the crystalline oxide film is not particularly limited, and may be a β-gallium structure, a corundum structure, or an orthorhombic crystal structure. A film containing a mixture of multiple crystal structures or polycrystals may be used, but a single crystal or uniaxially oriented film is preferred.

[0054] The crystalline oxide film according to the present invention is also a crystalline oxide film containing gallium as a main component. Generally, oxide films are composed of metal and oxygen, but the crystalline oxide film according to the present invention only needs to contain gallium as the main component of the metal. In the present invention, "containing gallium as a main component" means that 50 to 100 atomic % of the metal components is gallium. The metal components other than gallium may include, for example, one or more metals selected from iron, indium, aluminum, vanadium, titanium, chromium, rhodium, iridium, nickel, and cobalt.

[0055] The crystalline oxide film may contain a dopant element. Examples of the dopant include, but are not limited to, n-type dopants such as tin, germanium, silicon, titanium, zirconium, vanadium, or niobium, or p-type dopants such as copper, silver, tin, iridium, rhodium, or magnesium. The dopant concentration is, for example, about 1×10 16 / cm 3 ~1×10 22 / cm 3 may be about 1 x 10 17 / cm 3 Even at a low concentration of less than 1 × 10 20 / cm 3 A concentration higher than this may be used.

[0056] The thickness of the crystalline oxide film is not particularly limited, but is preferably 1 μm or more. There is no particular upper limit. For example, it may be 100 μm or less, preferably 50 μm or less, and more preferably 20 μm or less.

[0057] There is no particular limitation on the size of the crystalline oxide film, but the surface area of ​​the crystalline oxide film must be 100 mm 2 If the diameter is 2 inches (50 mm) or more, a large-area film with good crystallinity can be obtained, which is preferable.

[0058] Such a crystalline oxide film according to the present invention can be obtained with a high yield by a simple process as will be described later.

[0059] (Laminated structure) Any of the above crystalline oxide films may form a layered structure together with an underlying substrate. Fig. 1 shows a preferred example of a semiconductor device 100 using a layered structure 110 according to the present invention. As shown in Fig. 1, the layered structure 110 according to the present invention includes an underlying substrate 101 and any of the above crystalline oxide films 103.

[0060] Another layer may be interposed between the base substrate 101 and the crystalline oxide film 103. This other layer has a different composition from the base substrate 101 and the outermost crystalline oxide film 103, and is also called a buffer layer. The buffer layer may be any of a crystalline oxide film, a semiconductor film, an insulating film, a metal film, etc., and suitable materials include Al2O3, Ga2O3, Cr2O3, Fe2O3, In2O3, Rh2O3, V2O3, Ti2O3, and Ir2O3, or solid solutions thereof may also be used. The thickness of the buffer layer is preferably 0.1 μm to 2 μm.

[0061] (Base substrate) The base substrate 101 in the layered structure 110 according to the present invention is not particularly limited as long as it is suitable for growing the crystalline oxide film 103 and serves as a support. When forming a layered structure by bonding a base substrate to a crystalline oxide film, the material is not particularly limited, and known substrates can be used, including organic and inorganic compounds. Examples include polysulfone, polyethersulfone, polyphenylene sulfide, polyetheretherketone, polyimide, polyetherimide, fluororesin, metals such as iron, aluminum, stainless steel, and gold, quartz, glass, calcium carbonate, gallium oxide, and ZnO. In addition, examples include single-crystal substrates such as silicon, sapphire, lithium tantalate, lithium niobate, SiC, GaN, iron oxide, and chromium oxide. These single-crystal substrates are desirable for the layered structure 110 according to the present invention. These substrates enable the production of a higher-quality crystalline oxide film 103. In particular, sapphire substrates, lithium tantalate substrates, and lithium niobate substrates are relatively inexpensive and industrially advantageous.

[0062] As will be explained in detail later, when a crystalline oxide film is to be grown on a base substrate, a base substrate suitable for growth is selected.

[0063] The thickness of the base substrate is preferably 100 to 5000 μm, as this range makes it easy to handle and reduces thermal resistance during film formation, making it easier to obtain a high-quality film.

[0064] (Configuration example of semiconductor device) In the example of a semiconductor device 100 shown in FIG. 1, a crystalline oxide film 103 is formed on an underlying substrate 101. The crystalline oxide film 103 is configured by laminating an insulating thin film 103a and a conductive thin film 103b in this order from the underlying substrate 101 side. A gate insulating film 105 is formed on the conductive thin film 103b. A gate electrode 107 is formed on the gate insulating film 105. Furthermore, source-drain electrodes 109 are formed on the conductive thin film 103b so as to sandwich the gate electrode 107. With this configuration, it is possible to control the depletion layer formed in the conductive thin film 103b by applying a gate voltage to the gate electrode 107, enabling transistor operation (FET device).

[0065] Examples of semiconductor devices formed using the stacked structure according to the present invention include transistors such as MIS, HEMT, and IGBT, TFTs, Schottky barrier diodes using semiconductor-metal junctions, PN or PIN diodes combined with other P layers, and light-emitting / receiving elements. The stacked structure according to the present invention is useful for improving the characteristics of these devices.

[0066] The above-described laminated structure can be formed by known methods such as vapor deposition, MBE, sputtering, CVD, mist CVD, and liquid phase epitaxy.

[0067] The method for producing a crystalline oxide film or a laminated structure according to the present invention will be described below using the mist CVD method as an example. Note that the term "mist" as used herein refers to liquid particles dispersed in a gas, and includes what is called fog, droplets, etc.

[0068] (Film forming equipment) First, a film formation apparatus (mist CVD apparatus) used in the mist CVD method suitable for manufacturing the laminated structure according to the present invention will be described. Figure 2 shows an example of a film formation apparatus 201 used in the mist CVD method. The film formation apparatus 201 includes at least a mist-forming unit 220 that generates mist by turning a raw material solution 204a into mist, a carrier gas supply unit 230 that supplies a carrier gas that transports the mist, a supply pipe 209 that connects the mist-forming unit 220 to a film formation chamber 207 and transports the mist by the carrier gas, and the film formation chamber 207 that heat-treats the mist supplied from the supply pipe 209 together with the carrier gas to form a film on a base substrate 210.

[0069] (Mist generating section) The mist generating section 220 generates mist by turning the raw solution 204a into mist. The mist generating means is not particularly limited as long as it can turn the raw solution 204a into mist, and any known mist generating means may be used, but it is preferable to use a mist generating means that uses ultrasonic vibrations, as this allows for more stable mist generation.

[0070] An example of such a mist-generating unit 220 is shown in FIG. 3. The mist-generating unit 220 may include a mist source 204 containing raw solution 204a, a container 205 containing a medium capable of transmitting ultrasonic vibrations, such as water 205a, and an ultrasonic vibrator 206 attached to the bottom of the container 205. Specifically, the mist source 204, which is a container containing raw solution 204a, may be housed in the container 205 containing water 205a using a support (not shown). The bottom of the container 205 may be equipped with an ultrasonic vibrator 206, or the ultrasonic vibrator 206 may be connected to an oscillator 216. When the oscillator 216 is activated, the ultrasonic vibrator 206 vibrates, and ultrasonic waves propagate through the water 205a into the mist source 204, thereby turning the raw solution 204a into mist.

[0071] (Raw material solution) The raw material solution 204a contains gallium and may be any material, inorganic or organic, as long as it can be formed into a mist. Metals or metal compounds are suitable as the materials other than gallium, including, for example, one or more metals selected from iron, indium, aluminum, vanadium, titanium, chromium, rhodium, nickel, and cobalt. The raw material solution may be a solution in which a metal is dissolved or dispersed in an organic solvent or water in the form of a complex or salt. Examples of salts include halide salts such as metal chlorides, metal bromides, and metal iodides. Furthermore, solutions in which the above metals are dissolved in hydrogen halides such as hydrobromic acid, hydrochloric acid, and hydroiodic acid can also be used. Examples of complexes include acetylacetonate complexes, carbonyl complexes, ammine complexes, and hydride complexes. An acetylacetonate complex can also be formed by mixing acetylacetone with the aforementioned salt solution. The metal concentration in the raw material solution 204a is not particularly limited and can be set to 0.005 to 1 mol / L, etc. The temperature during mixing and dissolution is preferably 20° C. or higher.

[0072] The raw material solution may contain additives such as hydrohalic acid and oxidizing agents. Examples of hydrohalic acids include hydrobromic acid, hydrochloric acid, and hydroiodic acid, with hydrobromic acid and hydroiodic acid being preferred. Examples of oxidizing agents include peroxides such as hydrogen peroxide (HO), sodium peroxide (NaO), barium peroxide (BaO), and benzoyl peroxide (CHCO)O, as well as hypochlorous acid (HClO), perchloric acid, nitric acid, ozone water, and organic peroxides such as peracetic acid and nitrobenzene.

[0073] The raw material solution may contain a dopant. The dopant is not particularly limited. Examples of the dopant include n-type dopants such as tin, germanium, silicon, titanium, zirconium, vanadium, and niobium, and p-type dopants such as copper, silver, iridium, rhodium, and magnesium.

[0074] (Carrier gas supply unit) 2, the carrier gas supply unit 230 has a carrier gas source 202a that supplies a carrier gas. In this case, a flow rate control valve 203a for adjusting the flow rate of the carrier gas sent out from the carrier gas source 202a may be provided. In addition, if necessary, a dilution carrier gas source 202b for supplying a dilution carrier gas and a flow rate control valve 203b for adjusting the flow rate of the dilution carrier gas sent out from the dilution carrier gas source 202b may also be provided.

[0075] The type of carrier gas is not particularly limited and can be selected appropriately depending on the film to be formed. Examples include inert gases such as oxygen, ozone, nitrogen, and argon, and reducing gases such as hydrogen gas and forming gas. The type of carrier gas may be one or more. For example, a dilution gas obtained by diluting the same gas as the first carrier gas with another gas (e.g., diluted 10 times) may be used as the second carrier gas, or air may be used. The flow rate of the carrier gas is not particularly limited. For example, when forming a film on a substrate with a diameter of 2 inches (approximately 50 mm), the flow rate of the carrier gas is preferably 0.05 to 50 L / min, and more preferably 5 to 20 L / min.

[0076] (supply pipe) The film forming apparatus 201 has a supply pipe 209 that connects the mist generating unit 220 and the film forming chamber 207. In this case, the mist is carried by a carrier gas from the mist generating source 204 of the mist generating unit 220 through the supply pipe 209 and supplied into the film forming chamber 207. The supply pipe 209 may be, for example, a quartz tube, a glass tube, or a resin tube.

[0077] (Film forming chamber) A base substrate 210 is placed in the film formation chamber 207, and a heater 208 for heating the base substrate 210 may be provided. The heater 208 may be provided outside the film formation chamber 207 as shown in FIG. 2, or may be provided inside the film formation chamber 207. The mist supplied from the supply pipe 209 passes through piping inside the film formation chamber 207 and is ejected from a nozzle toward the base substrate 210 together with the carrier gas. The film formation chamber 207 may also be provided with an exhaust gas outlet 212 at a position that does not affect the supply of mist to the base substrate 210. The base substrate 210 may be placed face-down, for example, on the top surface of the film formation chamber 207, or may be placed face-up, for example, on the bottom surface of the film formation chamber 207.

[0078] (Base substrate) The base substrate used for film growth is preferably one that exhibits a maximum reflection intensity (reflection output) within a certain range of 2θ and ω (having a maximum point) when φ, ω, and 2θ are scanned as described above using CuKα rays generated from an X-ray source.

[0079] Specifically, when sapphire is used as the base substrate, the maximum reflection intensity may be observed when 17.70°<2θ<41.40° and 21.00°<ω<32.90°. In this case, it is preferable that the reflection intensity is 41.60°<ω+θ<41.90°. By using such a base substrate, it is possible to produce a crystalline oxide film in which the reflection output when scanning ω and 2θ has maximum points at 16.20°<2θ<39.90° and 20.30°<ω<32.20°, and the ω and θ at which the reflection output is maximum are 40.10°<ω+θ<40.40°.

[0080] Furthermore, when sapphire is used as the base substrate, the maximum reflection intensity may be observed when 28.60°<2θ<52.30° and 26.50°<ω<38.40°. In this case, it is preferable that 52.50°<ω+θ<52.80°. By using such a base substrate, it is possible to produce a crystalline oxide film in which the reflection output when scanning ω and 2θ has a maximum point when 26.20°<2θ<49.90° and 25.30°<ω<37.20°, and the ω and θ at which the reflection output is maximum is 50.10°<ω+θ<50.40°.

[0081] Furthermore, when sapphire is used as the base substrate, the maximum reflection intensity may be observed when the angles are 13.80°<2θ<37.50° and 19.10°<ω<31.00°. In this case, it is preferable that the angle is 37.70°<ω+θ<38.00°. By using such a base substrate, it is possible to produce a crystalline oxide film in which the reflection output when scanning ω and 2θ has maximum points at 12.00°<2θ<35.70° and 18.20°<ω<30.10°, and the ω and θ at which the reflection output is maximum are in the range of 35.90°<ω+θ<36.20°.

[0082] Furthermore, when sapphire is used as the base substrate, the maximum reflection intensity may be observed when 44.30°<2θ<68.00° and 34.30°<ω<46.20°. In this case, it is preferable that 68.20°<ω+θ<68.50°. By using such a base substrate, it is possible to produce a crystalline oxide film in which the reflection output when scanning ω and 2θ has a maximum point at 40.80°<2θ<64.50° and 32.60°<ω<44.50°, and the ω and θ at which the reflection output is maximum is 64.70°<ω+θ<65.00°.

[0083] Furthermore, when lithium tantalate is used as the base substrate, the maximum reflection intensity may be observed when the angles are 15.20°<2θ<38.90° and 19.80°<ω<31.70°. In this case, the angle is preferably 39.10°<ω+θ<39.40°. Using such a base substrate, a crystalline oxide film can be produced in which the reflection output when scanning ω and 2θ has a maximum point when the angles are 16.20°<2θ<39.90° and 20.30°<ω<32.20°, and the angle of ω and θ at which the reflection output is maximum is 40.10°<ω+θ<40.40°.

[0084] Furthermore, when lithium tantalate is used as the base substrate, the maximum reflection intensity may be observed when the angles are 24.50°<2θ<48.30° and 24.40°<ω<36.40°. In this case, the angle is preferably 48.40°<ω+θ<48.80°. Using such a base substrate, a crystalline oxide film can be produced in which the reflection output when scanning ω and 2θ has maximum points at 26.20°<2θ<49.90° and 25.30°<ω<37.20°, and the ω and θ at which the reflection output is maximum are in the range of 50.10°<ω+θ<50.40°.

[0085] Furthermore, when lithium tantalate is used as the base substrate, the maximum reflection intensity may occur when the angles are 10.80°<2θ<34.50° and 17.60°<ω<29.50°. In this case, the angle is preferably 34.70°<ω+θ<35.00°. Using such a base substrate, a crystalline oxide film can be produced in which the reflection output when scanning ω and 2θ has maximum points at 12.00°<2θ<35.70° and 18.20°<ω<30.10°, and the ω and θ at which the reflection output is maximum are 35.90°<ω+θ<36.20°.

[0086] Furthermore, when lithium tantalate is used as the base substrate, the maximum reflection intensity may be observed when the angles are 38.40°<2θ<62.10° and 31.40°<ω<43.30°. In this case, it is preferable that the angle is 62.30°<ω+θ<62.60°. Using such a base substrate, a crystalline oxide film can be produced in which the reflection output when scanning ω and 2θ has a maximum point at 40.80°<2θ<64.50° and 32.60°<ω<44.50°, and the ω and θ at which the reflection output is maximized are 64.70°<ω+θ<65.00°.

[0087] By using such a base substrate for film formation, the film can grow while inheriting the information of the base substrate, and the crystalline oxide film of the present invention can be obtained. Such a base substrate can be obtained, for example, by preparing base substrates with finely varied plane orientations on the film formation surface, and selecting the above-mentioned base substrates by performing X-ray diffraction measurement.

[0088] (Film forming method) Next, an example of a method for manufacturing a laminated structure according to the present invention will be described with reference to Fig. 2. The mist CVD method generally comprises a mist generating step of generating mist by misting a raw material solution containing gallium in a mist generating section, a carrier gas supply step of supplying a carrier gas for transporting the mist to the mist generating section, a transport step of transporting the mist from the mist generating section to the film forming chamber by the carrier gas via a supply pipe connecting the mist generating section to the film forming chamber, and a film forming step of heat-treating the transported mist to form a film on a base substrate.

[0089] The raw material solution 204a mixed as described above is placed in the mist generation source 204, the base substrate 210 is placed in the film formation chamber 207, and the heater 208 is activated. Next, the flow rate control valves 203a and 203b are opened to supply carrier gas from the carrier gas source 202a and the dilution carrier gas source 202b into the film formation chamber 207, and after the atmosphere in the film formation chamber 207 has been sufficiently replaced with the carrier gas, the flow rates of the carrier gas and the dilution carrier gas are adjusted, respectively.

[0090] Next, in the mist generating step, the ultrasonic vibrator 206 is vibrated, and the vibration is propagated to the raw material solution 204a through the water 205a, thereby turning the raw material solution 204a into mist and generating the mist.

[0091] Next, in the carrier gas supply step, a carrier gas for transporting the mist is supplied to the mist-forming section 220.

[0092] Next, in the transport step, the mist is transported by a carrier gas from the mist-generating section 220 to the film-forming chamber 207 via the supply pipe 209 connecting the mist-generating section 220 and the film-forming chamber 207.

[0093] Next, in the film-forming step, the mist transported to the film-forming chamber 207 is heated to cause a thermal reaction, thereby forming a film on a part or the entire surface of the base substrate 210 .

[0094] Thermal reactions require heating to promote the reaction of gallium and other elements contained in the mist. Therefore, the substrate surface temperature during the reaction must be at least 400°C or higher. Unlike other CVD methods, mist CVD requires the raw materials to reach the substrate surface in a mist-like liquid state. This significantly reduces the substrate surface temperature. Therefore, the substrate surface temperature during the reaction differs from the temperature set in the equipment. It is preferable to measure and control the substrate surface temperature during the reaction. However, if this is difficult, the reaction can be simulated by introducing only carrier gas or a water mist containing no solute, and the temperature can be measured instead.

[0095] Furthermore, the thermal reaction also depends on the temperature of the environment around the base substrate. Therefore, it is desirable that the temperature of the nozzle and the inner wall of the film formation chamber be higher than room temperature. This is to stabilize the thermal reaction. For example, the nozzle temperature can be set to 50 to 250°C.

[0096] The thermal reaction may be carried out under any of the following atmospheres: vacuum, non-oxygen atmosphere, reducing gas atmosphere, air atmosphere, and oxygen atmosphere, and may be appropriately set depending on the film to be formed. The reaction pressure may be atmospheric pressure, pressurized pressure, or reduced pressure, but film formation under atmospheric pressure is preferred because it simplifies the device configuration.

[0097] (Buffer layer formation) As described above, a buffer layer may be appropriately provided between the base substrate and the crystalline oxide film. The buffer layer can be formed by any known method, such as sputtering or vapor deposition. However, the mist CVD method described above allows for easy formation by simply changing the source solution. Specifically, a source aqueous solution can be suitably used in which one or more metals selected from aluminum, gallium, chromium, iron, indium, rhodium, vanadium, titanium, and iridium are dissolved or dispersed in water in the form of a complex or salt. Examples of complexes include acetylacetonate complexes, carbonyl complexes, ammine complexes, and hydride complexes. Examples of salts include metal chlorides, metal bromides, and metal iodides. Furthermore, solutions of the above metals in hydrobromic acid, hydrochloric acid, hydroiodic acid, etc. can also be used as salt aqueous solutions. In this case, the solute concentration is preferably 0.005 to 1 mol / L, and the dissolution temperature is preferably 20°C or higher. The buffer layer can be formed by maintaining the other conditions in the same manner as above. After the buffer layer is formed to a predetermined thickness, film formation is carried out by the method described above.

[0098] In a special case of the buffer layer formation method, the same material as that of the crystalline oxide film is used. In this case, the deposition temperature of the buffer layer may be higher than that of the crystalline oxide film. For example, the deposition temperature of the buffer layer may be 450°C and that of the crystalline oxide film may be 400°C, or the buffer layer may be deposited at 500°C and the crystalline oxide film at 450°C. This further improves the crystallinity of the crystalline oxide film.

[0099] (Heat treatment) The laminated structure according to the present invention may also be heat-treated at 200 to 600°C. This further removes unreacted species from the crystalline oxide film, resulting in a higher quality laminated structure. The heat treatment may be carried out in air, an oxygen atmosphere, or an inert gas atmosphere such as nitrogen or argon. The heat treatment time can be determined as appropriate, but may be, for example, 5 to 240 minutes.

[0100] (peeling) In the layered structure according to the present invention, the crystalline oxide film may be peeled off from the base substrate. The peeling means is not particularly limited and may be any known means. Examples of peeling methods include peeling by applying mechanical impact, peeling by applying heat and using thermal stress, peeling by applying vibration such as ultrasonic waves, and peeling by etching. By such peeling, the crystalline oxide film can be obtained as a free-standing film.

[0101] (Other manufacturing methods) Although the mist CVD method has been used as an example to explain the method for producing a crystalline oxide film according to the present invention, the crystalline oxide film according to the present invention can also be produced by methods other than the mist CVD method. In this way, the crystalline oxide film according to the present invention can be obtained with a high yield through a simple process. [Example]

[0102] EXAMPLES The present invention will be specifically explained below using examples and comparative examples, but the present invention is not limited to these.

[0103] [Example 1] 2, a film formation apparatus 201 used in this example will be described. The film formation apparatus 201 includes a carrier gas source 202a for supplying a carrier gas, a flow rate control valve 203a for adjusting the flow rate of the carrier gas delivered from the carrier gas source 202a, a dilution carrier gas source 202b for supplying a dilution carrier gas, a flow rate control valve 203b for adjusting the flow rate of the dilution carrier gas delivered from the dilution carrier gas source 202b, a mist generation source 204 containing a raw material solution 204a, a container 205 containing water 205a, an ultrasonic vibrator 206 attached to the bottom of the container 205, a film formation chamber 207 equipped with a heater 208, and a quartz supply pipe 209 connecting the mist generation source 204 to the film formation chamber 207.

[0104] (Base substrate) A 4-inch (100 mm) sapphire substrate was prepared as the base substrate 210. ω-2θ measurement was performed on this substrate using an X-ray diffractometer, and while capturing the peak derived from the base substrate, the angle φ around the φ axis perpendicular to the surface of the base substrate 210 was scanned. After fixing φ at the angle where the detected intensity was maximized, 2θ and ω were scanned independently, resulting in a maximum detected output at ω = 24.86° and 2θ = 33.72°. ω + θ at this time was 41.72°.

[0105] (n + Gallium oxide film deposition This base substrate 210 was placed in the film-forming chamber 207, the heater 208 was set to 450° C., the temperature was raised, and the chamber was left standing for 30 minutes to stabilize the temperature inside the film-forming chamber including the nozzle. The raw material solution 204a used ultrapure water as the solvent and gallium bromide as the solute. The gallium concentration in the raw material solution was 0.1 mol / L, and tin bromide was mixed so that the atomic ratio of tin to gallium was 1:0.08. This raw material solution 204a was placed in the mist generation source 204. Next, flow control valves 203a and 203b were opened to supply carrier gas from carrier gas source 202a and dilution carrier gas source 202b into the film formation chamber 207. After the atmosphere in the film formation chamber 207 was sufficiently replaced with the carrier gas, the flow rates of the carrier gas and dilution carrier gas were adjusted to 2 L / min and 6 L / min, respectively. Nitrogen was used as the carrier gas and dilution carrier gas. Next, ultrasonic vibrator 206 was vibrated at 2.4 MHz, and the vibrations were propagated to raw material solution 204a through water 205a, thereby misting raw material solution 204a to generate mist. This mist was introduced into film formation chamber 207 via supply pipe 209 by a carrier gas, and the mist was thermally reacted on base substrate 210 to form a thin film of gallium oxide on base substrate 210. The film formation time was 180 minutes.

[0106] (evaluation) The formation of α-Ga2O3 was confirmed by X-ray diffraction for the thin film formed on the base substrate 210. Furthermore, the film thickness was measured with an optical interference type film thickness meter and found to be 7.8 μm.

[0107] (n - Gallium oxide film deposition Subsequently, n - A gallium oxide film was formed. + The mold semiconductor film was placed in the film-forming chamber 207, the heater 208 was set to 450° C., the temperature was raised, and the chamber was left standing for 30 minutes to stabilize the temperature inside the film-forming chamber including the nozzle. The raw material solution 204a used ultrapure water as a solvent and gallium bromide as a solute. The gallium concentration in the raw material solution was 0.1 mol / L. This raw material solution 204a was placed in the mist generation source 204. Next, flow control valves 203a and 203b were opened to supply carrier gas from the carrier gas source 202a and dilution carrier gas source 202b into the film formation chamber 207. After the atmosphere in the film formation chamber 207 was sufficiently replaced with the carrier gas, the flow rates of the carrier gas and dilution carrier gas were adjusted to 2 L / min and 6 L / min, respectively. Nitrogen was used as the carrier gas and dilution carrier gas. Next, ultrasonic vibrator 206 was vibrated at 2.4 MHz, and the vibrations were propagated to raw material solution 204a through water 205a, thereby misting raw material solution 204a to generate mist. This mist was introduced into film formation chamber 207 via supply pipe 209 by a carrier gas, and the mist was thermally reacted on base substrate 210 to form a thin film of gallium oxide on base substrate 210. The film formation time was 120 minutes.

[0108] (evaluation) X-ray diffraction confirmed the formation of α-Ga2O3 in the obtained thin film. Furthermore, ω-2θ measurements were performed to capture the peaks originating from the substrate. The angle φ around the φ axis perpendicular to the thin film surface was scanned, and after fixing φ at the angle where the detected intensity was maximized, 2θ and ω were scanned independently. The detected output (reflected output) reached its maximum (maximum) at ω = 24.14° and 2θ = 32.28°. At this time, ω + θ was 40.28°.

[0109] (Formation of the first metal layer (Schottky electrode)) n - On the semiconductor layer, a Pt layer, a Ti layer, and an Au layer were deposited by electron beam evaporation. The Pt layer was 10 nm thick, the Ti layer was 4 nm thick, and the Au layer was 175 nm thick.

[0110] (Formation of second metal layer (ohmic electrode)) n +A Ti layer and an Au layer were deposited on the semiconductor layer by electron beam evaporation, with the Ti layer having a thickness of 35 nm and the Au layer having a thickness of 175 nm.

[0111] (evaluation) The SBDs were subjected to IV measurements, and the yield was investigated, with a breakdown voltage of 600 V or higher being considered a pass, and 88% passed.

[0112] [Example 2] Film formation, device fabrication, and evaluation were carried out in the same manner as in Example 1, except that a sapphire substrate was used as the base substrate 210, for which the detection output was maximized at ω=21.06° and 2θ=41.32° (ω+θ=41.72°) by X-ray diffraction. - X-ray diffraction of the layer showed that the maximum detection output was obtained at ω=20.34° and 2θ=39.88°. At this time, ω+θ was 40.28°. When the pressure resistance yield was investigated, 82% passed.

[0113] [Example 3] Film formation, device fabrication, and evaluation were carried out in the same manner as in Example 1, except that a sapphire substrate was used as the base substrate 210, for which the detection output was maximized at ω=32.86° and 2θ=17.72° (ω+θ=41.72°) by X-ray diffraction. - X-ray diffraction of this layer showed that the maximum detection output was obtained at ω=32.14° and 2θ=16.28°. At this time, ω+θ was 40.28°. When the pressure resistance yield was investigated, 80% passed.

[0114] [Example 4] Film formation, device fabrication, and evaluation were carried out in the same manner as in Example 1, except that a sapphire substrate was used as the base substrate 210, for which the detection output was maximized at ω=40.18° and 2θ=56.36° (ω+θ=68.36°) by X-ray diffraction. - X-ray diffraction of this layer showed that the maximum detection output was obtained at ω=38.41° and 2θ=52.82°. At this time, ω+θ was 64.82°. When the pressure resistance yield was investigated, 90% passed.

[0115] [Example 5] Film formation, device fabrication, and evaluation were carried out in the same manner as in Example 1, except that a sapphire substrate was used as the base substrate 210, for which the detection output was maximized at ω=20.93° and 2θ=33.85° (ω+θ=37.86°) by X-ray diffraction. - X-ray diffraction of this layer showed that the maximum detection output was at ω=20.03° and 2θ=32.05°. At this time, ω+θ was 36.06°. When the pressure resistance yield was investigated, 83% passed.

[0116] [Example 6] Film formation, device fabrication, and evaluation were carried out in the same manner as in Example 1, except that a sapphire substrate was used as the base substrate 210, for which the detection output was maximized at ω=34.32° and 2θ=36.64° (ω+θ=52.64°) by X-ray diffraction. - X-ray diffraction of this layer showed that the maximum detection output was obtained at ω=33.14° and 2θ=34.27°. At this time, ω+θ was 50.28°. When the pressure resistance yield was investigated, 85% passed.

[0117] [Comparative Example] Film formation, device fabrication, and evaluation were carried out in the same manner as in Example 1, except that a sapphire substrate was used as the base substrate 210, for which the detection output was maximized at ω=20.86° and 2θ=41.72° (ω+θ=41.72°) by X-ray diffraction. - X-ray diffraction of this layer showed that the maximum detection output was obtained at ω=20.14° and 2θ=40.28°. At this time, ω+θ was 40.28°. When the pressure resistance yield was investigated, 32% passed.

[0118] [Example 7] Film formation, device fabrication, and evaluation were carried out in the same manner as in Example 1, except that a lithium tantalate substrate was used as the base substrate 210, which showed a maximum detection output at ω=23.61° and 2θ=31.22° (ω+θ=39.22°) by X-ray diffraction. -X-ray diffraction of this layer showed that the maximum detection output was obtained at ω=24.14° and 2θ=32.28°. At this time, ω+θ was 40.28°. When the pressure resistance yield was investigated, 82% passed.

[0119] [Example 8] Film formation, device fabrication, and evaluation were carried out in the same manner as in Example 1, except that a sapphire substrate was used as the base substrate 210, for which the detection output was maximized at ω=34.40° and 2θ=67.92° (ω+θ=68.36°) by X-ray diffraction. - X-ray diffraction of this layer showed that the maximum detection output was at ω=32.63° and 2θ=64.38°. At this time, ω+θ was 64.82°. When the pressure resistance yield was investigated, 83% passed.

[0120] [Example 9] Film formation, device fabrication, and evaluation were carried out in the same manner as in Example 1, except that a sapphire substrate was used as the base substrate 210, for which the detection output was maximized at ω=46.13° and 2θ=44.46° (ω+θ=68.36°) by X-ray diffraction. - X-ray diffraction of this layer showed that the maximum detection output was at ω=44.36° and 2θ=40.92°. At this time, ω+θ was 64.82°. When the pressure resistance yield was investigated, 87% passed.

[0121] [Example 10] Film formation, device fabrication, and evaluation were carried out in the same manner as in Example 1, except that a sapphire substrate was used as the base substrate 210, for which the detection output was maximized at ω=19.22° and 2θ=37.26° (ω+θ=37.85°) by X-ray diffraction. - X-ray diffraction of the layer showed that the maximum detection output was obtained at ω=18.32° and 2θ=35.46°. At this time, ω+θ was 36.05°. When the pressure resistance yield was investigated, 80% passed.

[0122] [Example 11] Film formation, device fabrication, and evaluation were carried out in the same manner as in Example 1, except that a sapphire substrate was used as the base substrate 210, for which the detection output was maximized at ω=30.91° and 2θ=13.88° (ω+θ=37.85°) by X-ray diffraction. - X-ray diffraction of the layer showed that the maximum detection output was obtained at ω = 30.01° and 2θ = 12.08°. At this time, ω + θ was 36.05°. When the pressure resistance yield was investigated, 87% passed.

[0123] [Example 12] Film formation, device fabrication, and evaluation were carried out in the same manner as in Example 1, except that a sapphire substrate was used as the base substrate 210, for which the detection output was maximized at ω=26.59° and 2θ=52.10° (ω+θ=52.64°) by X-ray diffraction. - X-ray diffraction of this layer showed that the maximum detection output was obtained at ω=25.41° and 2θ=49.73°. At this time, ω+θ was 50.27°. When the pressure resistance yield was investigated, 89% passed.

[0124] [Example 13] Film formation, device fabrication, and evaluation were carried out in the same manner as in Example 1, except that a sapphire substrate was used as the base substrate 210, for which the detection output was maximized at ω=38.28° and 2θ=28.72° (ω+θ=52.64°) by X-ray diffraction. - X-ray diffraction of the layer showed that the maximum detection output was obtained at ω=37.10° and 2θ=26.35°. At this time, ω+θ was 50.27°. When the pressure resistance yield was investigated, 82% passed.

[0125] As described above, the yield of passing the voltage resistance test is significantly improved in all of the Examples compared to the Comparative Examples, which shows that the crystalline oxide film of the present invention has excellent voltage resistance.

[0126] The present invention is not limited to the above-described embodiments. The above-described embodiments are merely examples, and anything that has substantially the same configuration as the technical idea described in the claims of the present invention and that exhibits similar effects is included within the technical scope of the present invention.

Claims

1. A crystalline oxide film containing gallium as a main component, characterized in that, when CuKα rays are incident on the crystalline oxide film and X-ray diffraction is performed, the angle φ about the φ axis perpendicular to the surface of the crystalline oxide film is φ at which the peak derived from the crystalline oxide film in ω-2θ measurement is maximized, and the reflected output when scanning ω and 2θ has a maximum point when 16.20°<2θ<39.90° and 20.30°<ω<32.20°, and the ω and θ at which the reflected output is maximized are 40.10°<ω+θ<40.40°.

2. A crystalline oxide film containing gallium as a main component, characterized in that, when CuKα rays are incident on the crystalline oxide film and X-ray diffraction is performed, the angle φ about the φ axis perpendicular to the surface of the crystalline oxide film is φ at which the peak derived from the crystalline oxide film in ω-2θ measurement is maximized, and the reflected output when ω and 2θ are scanned has a maximum point when 2θ<49.90° and 25.30°<ω<37.20°, and the ω and θ at which the reflected output is maximized are in the range of 50.10°<ω+θ<50.40°.

3. A crystalline oxide film containing gallium as a main component, characterized in that, when CuKα rays are incident on the crystalline oxide film and X-ray diffraction is performed, the angle φ about the φ axis perpendicular to the surface of the crystalline oxide film is φ at which the peak derived from the crystalline oxide film in ω-2θ measurement is maximized, and the reflected output when scanning ω and 2θ has a maximum point when 12.00°<2θ<35.70° and 18.20°<ω<30.10°, and the ω and θ at which the reflected output is maximized are 35.90°<ω+θ<36.20°.

4. A crystalline oxide film containing gallium as a main component, characterized in that, when CuKα rays are incident on the crystalline oxide film and X-ray diffraction is performed, the angle φ about the φ axis perpendicular to the surface of the crystalline oxide film is φ at which a peak derived from the crystalline oxide film in ω-2θ measurement is maximized, and the reflected output when ω and 2θ are scanned has a maximum point when 40.80°<2θ<64.50° and 32.60°<ω<44.50°, and the ω and θ at which the reflected output is maximized are 64.70°<ω+θ<65.00°.

5. The surface area of ​​the crystalline oxide film is 100 mm ２ 5. The crystalline oxide film according to claim 1, wherein the thickness is 50 mm or more, or the diameter is 50 mm or more.

6. A laminated structure comprising at least a base substrate and the crystalline oxide film according to any one of claims 1 to 4.

7. A semiconductor device comprising the crystalline oxide film according to any one of claims 1 to 4.

8. A method for producing a crystalline oxide film containing gallium as a main component, comprising: forming the crystalline oxide film on a sapphire substrate as a base substrate, wherein, when CuKα rays are incident on the substrate and X-ray diffraction is performed, the reflected output when scanning ω and 2θ has a maximum value at 17.70°<2θ<41.40° and 21.00°<ω<32.90°, where φ is an angle around a φ axis perpendicular to the surface of the substrate and φ is such that a peak derived from the substrate in ω-2θ measurement is maximized, and the ω and θ at which the reflected output is maximized are such that 41.60°<ω+θ<41.90°.

9. A method for producing a crystalline oxide film containing gallium as a main component, comprising: forming the crystalline oxide film on a sapphire substrate as a base substrate, wherein, when CuKα rays are incident on the substrate and X-ray diffraction is performed, the reflected output when scanning ω and 2θ has a maximum point at 28.60°<2θ<52.30° and 26.50°<ω<38.40°, where φ is an angle about a φ axis perpendicular to the surface of the substrate, and φ is such that a peak derived from the substrate in ω-2θ measurement is maximized, and the ω and θ at which the reflected output is maximized are such that 52.50°<ω+θ<52.80°.

10. A method for producing a crystalline oxide film containing gallium as a main component, the method comprising: forming the crystalline oxide film on a sapphire substrate as a base substrate, wherein, when CuKα rays are incident on the substrate and X-ray diffraction is performed, the reflected output when scanning ω and 2θ has maximum points at 13.80°<2θ<37.50° and 19.10°<ω<31.00°, where φ is an angle around a φ axis perpendicular to the surface of the substrate and φ is such that a peak derived from the substrate in ω-2θ measurement is maximum, and the ω and θ at which the reflected output is maximum are 37.70°<ω+θ<38.00°.

11. A method for producing a crystalline oxide film containing gallium as a main component, comprising: forming the crystalline oxide film on a sapphire substrate as a base substrate, wherein, when CuKα rays are incident on the substrate and X-ray diffraction is performed, the reflected output when scanning ω and 2θ has a maximum point at 44.30°<2θ<68.00° and 34.30°<ω<46.20°, where φ is an angle about a φ axis perpendicular to the surface of the substrate and φ is such that a peak derived from the substrate in ω-2θ measurement is maximized, and the ω and θ at which the reflected output is maximized are such that 68.20°<ω+θ<68.50°.

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