Method for producing gallium oxide semiconductor film

Abstract

To provide a manufacturing method of an oxidation gallium semiconductor film by a mist CDV method, capable of obtaining the oxidation gallium semiconductor film of a high quality with excellent crystalline at a high productivity.SOLUTION: A manufacturing method of an oxidation gallium semiconductor film, includes steps of: transmitting a mist generated by performing atomization or droplet formation of an original solution by using a carrier gas, heating the mist, and forming a film by performing thermal reaction of the mist on a substrate. A hydrogen ion concentration in the original solution is set to 1×10-12 to 1×10-2 mol / L.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for producing a gallium oxide semiconductor film, in which a gallium oxide semiconductor film is formed on a substrate using a mist-like raw material. [Background technology]

[0002] High-vacuum deposition equipment capable of achieving non-equilibrium conditions, such as pulsed laser deposition (PLD), molecular beam epitaxy (MBE), and sputtering, has been developed, enabling the fabrication of oxide semiconductors that were previously impossible using melt deposition and other methods. Furthermore, mist chemical vapor deposition (Mist CVD), a method for growing crystals on a substrate using atomized mist-like raw materials, has also been developed. Unlike other CVD methods, Mist CVD does not require high temperatures and can even fabricate metastable crystal structures such as the corundum structure of α-Ga2O3. As a wide-bandgap semiconductor, α-Ga2O3 is expected to be applied to next-generation switching devices, where it can achieve high voltage resistance, low loss, and high heat resistance.

[0003] Regarding the mist CVD method, Patent Document 1 describes a tubular furnace type mist CVD apparatus. Patent Document 2 describes a fine channel type mist CVD apparatus. Patent Document 3 describes a linear source type mist CVD apparatus. Patent Document 4 describes a tubular furnace mist CVD apparatus, which differs from the mist CVD apparatus described in Patent Document 1 in that a carrier gas is introduced into the mist generator. Patent Document 5 describes a mist CVD apparatus in which a substrate is placed above a mist generator and a susceptor is a rotating stage mounted on a hot plate. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 1-257337 [Patent Document 2] Japanese Patent Application Laid-Open No. 2005-307238 [Patent Document 3] Japanese Patent Application Laid-Open No. 2012-46772 [Patent Document 4] Patent No. 5397794 [Patent Document 5] Japanese Patent Application Laid-Open No. 2014-63973 Summary of the Invention [Problem to be solved by the invention]

[0005] To produce gallium oxide, it is necessary to dissolve gallium in the raw material solution, so the raw material solution has typically been made strongly acidic, with a pH of about 1. For example, when gallium bromide or gallium iodide is dissolved in water, the halide ions ionize, making the solution acidic. Gallium acetylacetonate does not dissolve in water as is, so an acid is added to promote dissolution. Additionally, aqueous solutions of metallic gallium dissolved in hydrochloric acid, etc., also become strongly acidic.

[0006] The inventors have investigated and found that when a film is formed by mist CVD using a strong acid solution as a raw material solution, the metal components constituting the film formation apparatus are dissolved to a considerable extent. As a result, it was found that the dissolved metal is incorporated into the formed gallium oxide film, causing crystal defects and recombination centers, resulting in a deterioration in film quality. Furthermore, it was found that not only the film formation apparatus but also the associated equipment corrodes, requiring maintenance of the apparatus, which increases downtime, i.e., reduces productivity.

[0007] An object of the present invention is to provide a method for producing a gallium oxide semiconductor film by mist CVD, which can produce a high-quality gallium oxide semiconductor film with excellent crystallinity and other properties with high productivity. [Means for solving the problem]

[0008] The present invention has been made to achieve the above object, and provides a method for producing a gallium oxide semiconductor film, which comprises atomizing or dropletizing a raw material solution to produce a mist, transporting the mist using a carrier gas, heating the mist, and subjecting the mist to a thermal reaction on a substrate to form a film, the method comprising the steps of: adjusting the hydrogen ion concentration in the raw material solution to 1×10 -12 ~1×10 -2 The present invention provides a method for producing a gallium oxide semiconductor film with a gallium oxide concentration of 1000 mol / L.

[0009] According to this method for producing a gallium oxide semiconductor film, corrosion of the film-forming apparatus body is suppressed, thereby suppressing metal contamination of the gallium oxide semiconductor film due to elution of metal components, and thus enabling efficient production of a gallium oxide semiconductor film with good film quality. Furthermore, downtime of the film-forming apparatus and associated equipment due to maintenance and the like is reduced, improving productivity. Furthermore, it is now possible to replace film-forming apparatus components that have been made of non-metallic materials to prevent corrosion with metal components, thereby increasing the degree of freedom in apparatus design.

[0010] At this time, the hydrogen ion concentration in the raw material solution is 3×10 -11 ~3×10 -3 It can be expressed as mol / L.

[0011] This makes it possible to more effectively suppress corrosion of the film-forming equipment, reduce downtime, and more efficiently produce gallium oxide semiconductor films.

[0012] At this time, the hydrogen ion concentration in the raw material solution is set to 1×10 -6 ~1×10 -3 It can be expressed as mol / L.

[0013] This not only reduces metal contamination but also increases the deposition rate of the gallium oxide semiconductor film.

[0014] At this time, the hydrogen ion concentration can be controlled by adjusting the amount of acid and / or base in the raw material solution.

[0015] This makes it possible to easily control the hydrogen ion concentration in the raw material solution.

[0016] In this case, ammonia can be used as the base.

[0017] This makes it possible to manufacture a gallium oxide semiconductor film of higher purity and higher quality.

[0018] In this case, the substrate is a plate-shaped substrate having a surface area of ​​100 mm 2 The above can be used.

[0019] This allows for efficient production of large-area, high-quality gallium oxide semiconductor films. [Effects of the Invention]

[0020] As described above, the method for producing a gallium oxide semiconductor film according to the present invention can suppress corrosion of the film-forming apparatus. This not only suppresses metal contamination of the gallium oxide film due to elution of metal components and improves crystallinity, but also reduces downtime of the film-forming apparatus and associated equipment due to maintenance, etc., thereby improving productivity. Furthermore, it becomes possible to replace components made of non-metallic materials to prevent corrosion with metal, increasing the flexibility of apparatus design. Furthermore, it becomes possible to improve the film-forming rate. [Brief explanation of the drawings]

[0021] [Figure 1] 1 is a schematic diagram showing an example of a film forming apparatus that can be used in a method for producing a gallium oxide semiconductor film according to the present invention. [Figure 2] FIG. 4 is a diagram illustrating an example of a mist generating unit. [Figure 3] 1 shows the evaluation results of the full width at half maximum of the gallium oxide semiconductor films produced in the examples and comparative examples. [Figure 4] 4 shows the deposition rates of gallium oxide semiconductor films in Examples and Comparative Examples. DETAILED DESCRIPTION OF THE INVENTION

[0022] The present invention will be described in detail below, but the present invention is not limited thereto.

[0023] As described above, there has been a demand for a method for producing gallium oxide by mist CVD, which can produce high-quality gallium oxide semiconductor films with excellent crystallinity and other properties with high productivity.

[0024] As a result of intensive research into the above-mentioned problems, the present inventors have discovered a method for producing a gallium oxide semiconductor film, which comprises atomizing or dropletizing a raw material solution to generate mist, transporting the mist using a carrier gas, heating the mist, and subjecting the mist to a thermal reaction on a substrate to form a film, wherein the hydrogen ion concentration in the raw material solution is adjusted to 1×10 -12 ~1×10 -2 The present inventors have found that a method for producing a gallium oxide semiconductor film with a gallium oxide concentration of 1000 mol / L can efficiently produce a gallium oxide semiconductor film with better film quality, improve productivity, and further increase the degree of freedom in device design, and have completed the present invention.

[0025] The following description will be made with reference to the drawings.

[0026] Here, the term "mist" as used in the present invention refers to a general term for fine particles of liquid dispersed in a gas, and includes what is called fog, droplets, etc. Furthermore, when describing a numerical range, for example, "3 to 6," it means "3 or more and 6 or less."

[0027] (Film forming equipment) 1 shows an example of a film formation apparatus 101 that can be used in the method for producing a gallium oxide semiconductor film according to the present invention. The film formation apparatus 101 includes a mist-forming unit 120 that generates mist by misting a raw material solution, a carrier gas supply unit 130 that supplies a carrier gas for transporting the mist, a film formation unit 140 that heat-treats the mist to form a film on a substrate, and a transport unit 109 that connects the mist-forming unit 120 and the film formation unit 140 and transports the mist by the carrier gas. The operation of the film formation apparatus 101 may also be controlled by including a control unit (not shown) that controls all or part of the film formation apparatus 101.

[0028] (Raw material solution) The gallium oxide semiconductor film according to the present invention can further contain metals other than gallium, and therefore the raw material solution 104a is not particularly limited as long as it contains at least gallium and is a material that can be turned into mist. That is, in addition to gallium, the raw material solution 104a may contain, for example, one or more metals selected from iron, indium, aluminum, vanadium, titanium, chromium, rhodium, iridium, nickel, and cobalt.

[0029] The raw material solution 104a is not particularly limited as long as it can turn the material containing the metal into a mist, but the raw material solution 104a can be one in which the metal is 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 in which the metal is dissolved in hydrobromic acid, hydrochloric acid, hydroiodic acid, or the like can also be used as aqueous salt solutions.

[0030] The raw material solution may also contain a dopant. The dopant is not particularly limited. Examples include n-type dopants such as tin, germanium, silicon, titanium, zirconium, vanadium, and niobium, and p-type dopants such as copper, silver, tin, iridium, and rhodium. The dopant concentration is, for example, about 1×10 16 / cm3 ~1×10 22 / cm 3 may be about 1 x 10 17 / cm 3 Even at low concentrations below 1 × 10 20 / cm 3 A concentration higher than this may be used.

[0031] Furthermore, an acid can be mixed into the raw material solution 104a to dissolve the raw material. Examples of the acid include hydrogen halides such as hydrobromic acid, hydrochloric acid, and hydroiodic acid, halogen oxo acids such as hypochlorous acid, chlorous acid, hypobromous acid, bromous acid, hypoiodous acid, and iodic acid, formic acid, and nitric acid.

[0032] Furthermore, the hydrogen ion concentration (pH) can be adjusted by mixing a base into the raw solution 104a. In this way, the hydrogen ion concentration in the raw solution can be easily controlled. Examples of the base include potassium hydroxide, sodium hydroxide, ammonia, calcium hydroxide, barium hydroxide, magnesium hydroxide, copper hydroxide, and iron hydroxide. Among these, ammonia is particularly preferable because it has a low boiling point and leaves no residue when the solution is heated.

[0033] In the method for producing a gallium oxide semiconductor film according to the present invention, the hydrogen ion concentration in the raw material solution 104a is set to 1×10 -12 ~1×10 -2 The hydrogen ion concentration in the raw solution 104a can be controlled by adjusting the amount of acid and / or base in the raw solution 104a. -2 By keeping the hydrogen ion concentration at 1×10 mol / L or less (pH ≥ 2), corrosion of the film-forming equipment and elution of the equipment components can be suppressed, impurity contamination in the film can be suppressed, and a gallium oxide semiconductor film with good film quality can be efficiently produced. -12 By adjusting the pH to 12 or higher, a gallium oxide semiconductor film with good film quality can be efficiently and stably formed.

[0034] The hydrogen ion concentration in the raw solution 104a is set to 3×10 -11 ~3×10 -3 It is preferable that the hydrogen ion concentration in the raw material solution 104a is 1×10 mol / L. If the hydrogen ion concentration is in this range, corrosion of the equipment can be more reliably suppressed, downtime can be reduced, and a higher quality gallium oxide semiconductor film can be efficiently produced. Furthermore, it is preferable that the hydrogen ion concentration in the raw material solution 104a is 1×10 -6 ~1×10 -3 Within this range, in addition to the above effects, it is possible to improve the film formation rate.

[0035] (Mist generating section) In the mist generating section 120, the raw solution 104a is adjusted and the raw solution 104a is turned into mist to generate mist. The mist generating means is not particularly limited as long as it can turn the raw solution 104a 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.

[0036] An example of such a mist-generating unit 120 is shown in FIG. 2. For example, the mist-generating unit 120 may include a mist source 104 that contains raw solution 104a, a container 105 that contains a medium capable of transmitting ultrasonic vibrations, such as water 105a, and an ultrasonic vibrator 106 attached to the bottom of the container 105. More specifically, the mist source 104, which is a container that contains the raw solution 104a, is housed in the container 105 that contains the water 105a using a support (not shown). The bottom of the container 105 is equipped with an ultrasonic vibrator 106, which is connected to an oscillator 116. When the oscillator 116 is activated, the ultrasonic vibrator 106 vibrates, and ultrasonic waves propagate through the water 105a into the mist source 104, turning the raw solution 104a into mist.

[0037] (Transportation section) The transfer unit 109 connects the mist generation unit 120 and the film formation unit 140. Mist is transferred by a carrier gas from the mist generation source 104 of the mist generation unit 120 to the film formation chamber 107 of the film formation unit 140 via the transfer unit 109. The transfer unit 109 can be, for example, a supply pipe 109a. The supply pipe 109a can be, for example, a quartz pipe or a resin tube.

[0038] (Film forming section) In the film formation section 140, the mist is heated to cause a thermal reaction, thereby forming a film on a part or all of the surface of the substrate 110. The film formation section 140 includes, for example, a film formation chamber 107, in which the substrate 110 is installed, and a heating means for heating the substrate 110, such as a hot plate 108. The hot plate 108 may be installed outside the film formation chamber 107 as shown in FIG. 1, or may be installed inside the film formation chamber 107. In addition to the hot plate, heating by light or the like that can be absorbed by the substrate and generate heat is also possible. The film formation chamber 107 may also be provided with an exhaust gas exhaust port 112 at a position that does not affect the supply of mist to the substrate 110. The substrate 110 may be installed face-down, for example, on the top surface of the film formation chamber 107, or face-up, for example, on the bottom surface of the film formation chamber 107.

[0039] (Base) The substrate 110 is not particularly limited as long as it can be used to form a film and can support the film. The material of the substrate 110 is also not particularly limited, and known substrates can be used, and may be organic or inorganic compounds. Examples include, but are not limited to, polysulfone, polyethersulfone, polyphenylene sulfide, polyetheretherketone, polyimide, polyetherimide, fluororesin, metals such as iron, aluminum, stainless steel, and gold, silicon, sapphire, quartz, glass, and gallium oxide. The substrate may have any shape, and is effective for any shape, including, for example, a plate-like shape such as a flat plate or disc, a fiber-like shape, a rod-like shape, a cylindrical shape, a prismatic shape, a cylindrical shape, a spiral shape, a spherical shape, and a ring-like shape. In the present invention, a plate-like substrate is preferably used. The thickness of the plate-like substrate is not particularly limited, but is preferably 10 to 2000 μm, and more preferably 50 to 800 μm. When the substrate is plate-like, its area is 100 mm. 2 More preferably, the diameter is 2 inches (50 mm) or more.

[0040] (Carrier gas supply unit) The carrier gas supply unit 130 has a carrier gas source 102a that supplies a carrier gas, and may also be provided with a flow rate control valve 103a for adjusting the flow rate of the carrier gas (sometimes referred to as the "main carrier gas") delivered from the carrier gas source 102a. It may also be provided with a dilution carrier gas source 102b that supplies a dilution carrier gas as needed, and a flow rate control valve 103b for adjusting the flow rate of the dilution carrier gas delivered from the dilution carrier gas source 102b.

[0041] The type of carrier gas is not particularly limited and can be appropriately selected 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., 10 times dilution) may be used as a second carrier gas, or air may be used. In this specification, the term "carrier gas flow rate" simply refers to the total flow rate of the carrier gas. For example, the total flow rate of the main carrier gas delivered from the carrier gas source 102a and the dilution carrier gas delivered from the dilution carrier gas source 102b is defined as the carrier gas flow rate. The carrier gas flow rate is determined appropriately depending on, for example, the size of the film formation chamber, the film formation temperature, the raw material solution, etc., but can be, for example, approximately 2 to 30 L / min.

[0042] (Manufacturing method) Next, an example of a method for producing a gallium oxide semiconductor film according to the present invention will be described below with reference to FIG.

[0043] First, the raw material solution 104a adjusted to a desired hydrogen ion concentration (pH) is placed in the mist generating source 104 of the mist generating unit 120, the substrate 110 is placed on the hot plate 108 directly or through the wall of the film forming chamber 107, and the hot plate 108 is operated.

[0044] Next, the flow control valves 103a and 103b are opened to supply carrier gas from the carrier gas sources 102a and 102b into the film formation chamber 107, and the atmosphere in the film formation chamber 107 is thoroughly replaced with the carrier gas. At the same time, the flow rates of the main carrier gas and the dilution carrier gas are adjusted, respectively, to control the carrier gas flow rate.

[0045] Next, mist is generated. The ultrasonic vibrator 106 is vibrated, and the vibrations are propagated to the raw material solution 104a through the water 105a in the container 105, thereby turning the raw material solution 104a into mist and generating mist. Next, the mist generated in the mist generating unit 120 is transported by a carrier gas from the mist generating unit 120 through the transport unit 109 to the film forming unit 140, and then introduced into the film forming chamber 107. The mist introduced into the film forming chamber 107 is heat-treated by the heat of the hot plate 108 in the film forming chamber 107, causing a thermal reaction and forming a film on the substrate 110.

[0046] The thermal reaction may be carried out under any conditions as long as the mist reacts with heat. The reaction conditions are not particularly limited. They can be appropriately set depending on the raw materials and the film to be formed. For example, the heating temperature is in the range of 120 to 600°C, preferably 200 to 600°C, and more preferably 300 to 550°C.

[0047] The thermal reaction may be carried out under any of a non-oxygen atmosphere, a reducing gas atmosphere, an air atmosphere, and an oxygen atmosphere, and may be appropriately set depending on the film to be formed. The reaction pressure may be atmospheric pressure, elevated pressure, or reduced pressure, but film formation under atmospheric pressure is preferred because it simplifies the device configuration. [Example]

[0048] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.

[0049] Example 1 Based on the above-described method for manufacturing a gallium oxide semiconductor film, a gallium oxide (α-Ga2O3) film having a corundum structure was formed as an oxide semiconductor film containing gallium as the main component.

[0050] Specifically, first, gallium chloride 1 × 10 -1 mol / L aqueous solution, and add potassium hydroxide (KOH) to it to adjust the hydrogen ion concentration (pH) to 1×10 -2mol / L (pH=2), and this was designated as raw material solution 104a.

[0051] The raw material solution 104a obtained as described above was placed in the mist generating source 104. Next, a 4-inch (100 mm diameter) c-plane sapphire substrate was placed as the base 110 adjacent to the hot plate 108 in the film formation chamber 107. The hot plate 108 was then operated to raise the temperature to 500°C. Since it was necessary to minimize temperature fluctuations during film formation, the material of the film formation chamber 107 was aluminum, which has good thermal conductivity.

[0052] Next, the flow rate control valves 103a and 103b were opened to supply oxygen gas as a carrier gas from the carrier gas sources 102a and 102b into the film formation chamber 107, and the atmosphere in the film formation chamber 107 was thoroughly replaced with the carrier gas. After this, the flow rate of the main carrier gas was set to 8 L / min, and the flow rate of the dilution carrier gas was set to 18 L / min.

[0053] Next, the ultrasonic vibrator 106 was vibrated at 2.4 MHz, and the vibrations were propagated to the raw material solution 104a through the water 105a in the container 105, thereby misting the raw material solution 104a to generate mist. This mist was introduced into the film formation chamber 107 via the supply pipe 109a by means of a carrier gas. The mist was then thermally reacted in the film formation chamber 107 under atmospheric pressure and at 500°C to form a thin film of α-GaO on the substrate 110. The film formation time was 30 minutes.

[0054] The obtained samples were subjected to X-ray diffraction measurements to evaluate their crystallinity. Specifically, the rocking curve of the (0006) diffraction peak of α-Ga2O3 was measured, and its full width at half maximum was calculated. Furthermore, the degree of contamination in the film was evaluated using energy dispersive X-ray analysis (EDS). The film thickness was also measured using an interferometric film thickness meter. The film formation rate was calculated by dividing the obtained film thickness by the film formation time of 0.5 hours (30 minutes).

[0055] Example 2 The hydrogen ion concentration of the raw solution 104a is 1×10 -4The film was formed and evaluated under the same conditions as in Example 1, except for the above adjustment.

[0056] Example 3 The hydrogen ion concentration of the raw solution 104a is 1×10 -7 The film was formed and evaluated under the same conditions as in Example 1, except for the above adjustment.

[0057] Example 4 The hydrogen ion concentration of the raw solution 104a is 1×10 -9 The film was formed and evaluated under the same conditions as in Example 1, except for the above adjustment.

[0058] Example 5 The hydrogen ion concentration of the raw solution 104a is 1×10 -12 The film was formed and evaluated under the same conditions as in Example 1, except for the above adjustment.

[0059] Example 6 Film formation and evaluation were carried out under the same conditions as in Example 1, except that the hydrogen ion concentration (pH) was adjusted using ammonia water (NH3(aq)) instead of the potassium hydroxide (KOH) aqueous solution used in Example 1.

[0060] Example 7 The hydrogen ion concentration of the raw solution 104a is 1×10 -4 The film was formed and evaluated under the same conditions as in Example 6, except for the above adjustment.

[0061] Example 8 The hydrogen ion concentration of the raw solution 104a is 1×10 -7 The film was formed and evaluated under the same conditions as in Example 6, except for the above adjustment.

[0062] Example 9 The hydrogen ion concentration of the raw solution 104a is 1×10 -9The film was formed and evaluated under the same conditions as in Example 6, except for the above adjustment.

[0063] Example 10 The hydrogen ion concentration of the raw solution 104a is 1×10 -11 The film was formed and evaluated under the same conditions as in Example 6, except for the above adjustment.

[0064] Example 11 The hydrogen ion concentration of the raw solution 104a is 1×10 -3 The film was formed and evaluated under the same conditions as in Example 6, except for the above adjustment.

[0065] Example 12 The hydrogen ion concentration of the raw solution 104a is 1×10 -6 The film was formed and evaluated under the same conditions as in Example 6, except for the above adjustment.

[0066] (Comparative Example 1) Instead of potassium hydroxide in Example 1, a hydrogen bromide (HBr) aqueous solution was used to adjust the hydrogen ion concentration (pH), and the hydrogen ion concentration of the raw material solution 104a was adjusted to 1×10 -1 Film formation and evaluation were carried out under the same conditions as in Example 1, except that the pH was adjusted to 1.5 mol / L (pH = 1).

[0067] (Comparative Example 2) In Example 1, the hydrogen ion concentration of the raw material solution 104a was 1×10 -13 Film formation and evaluation were carried out under the same conditions as in Example 1, except that the pH was adjusted to 1.5 mol / L (pH = 13).

[0068] Table 1 shows the conditions of the raw material solutions and the evaluation results for Examples 1 to 12 and Comparative Examples 1 and 2. Furthermore, Fig. 3 shows the evaluation results of the full width at half maximum of the gallium oxide semiconductor films produced in the Examples and Comparative Examples, and Fig. 4 shows the film formation rates of the gallium oxide semiconductor films produced in the Examples and Comparative Examples.

[0069] [Table 1]

[0070] As is clear from Table 1, Examples 1 to 12 have smaller full widths at half maximum than Comparative Example 1, indicating that the crystallinity of the α-Ga2O3 film is superior. Furthermore, the EDS evaluation results show that Al, which is thought to be derived from the components constituting the manufacturing equipment, was detected in Comparative Example 1, but in Examples 1 to 12, elements other than Ga and O were not detected, and no impurity contamination was observed. This is thought to be because lowering the hydrogen ion concentration in the raw material solution suppresses elution from the components constituting the manufacturing equipment, including the film formation chamber, preventing impurity contamination in the film, and as a result, improving the crystallinity. Furthermore, Examples 1 to 12 showed an improved film formation rate compared to the Comparative Examples. In particular, when the hydrogen ion concentration was increased to 1×10 -3 ~1×10 -6 In Examples 2, 7, 11, and 12 in which the pH was 3.5-6, the film formation rate was significantly improved.

[0071] 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. [Explanation of symbols]

[0072] 101...film forming apparatus, 102a...carrier gas source, 102b...dilution carrier gas source, 103a...flow rate control valve, 103b...flow rate control valve, 104...mist source, 104a...raw material solution, 105...container, 105a...water, 106...ultrasonic vibrator, 107...film formation chamber, 108...hot plate, 109...transport unit, 109a...supply pipe, 110...base body, 112...exhaust port, 116...oscillator, 120... mist generating section, 130... carrier gas supply section, 140... film forming section.

Claims

1. A method for producing a gallium oxide semiconductor film, comprising: A film forming apparatus having metal members as components that come into contact with the mist is used, A method for producing a gallium oxide semiconductor film, comprising depositing a gallium oxide semiconductor film in which no metal elements other than Ga are detected by energy dispersive X-ray analysis (EDS).

2. 2. The method for producing a gallium oxide semiconductor film according to claim 1, wherein the gallium oxide semiconductor film is formed so that no metal elements other than Ga are detected in the energy dispersive X-ray analysis (EDS), thereby improving the crystallinity of the gallium oxide semiconductor film.

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