Film forming method, film forming apparatus, and alpha-Ga2O3 film

Abstract

The present invention is a film-forming method for forming a crystalline oxide film by a mist CVD method by supplying a carrier gas and mist to a heated substrate in a film-forming part covered by a partition wall, the method being characterized in that a gas other than the carrier gas is conveyed into the film-forming part at least during the heating of the substrate. As a result, provided is a film-forming method for forming a high-quality crystalline oxide film in which the particle density of the film surface is significantly reduced.

Description

Technical Field

[0001] The present invention relates to a film forming method, a film forming device and an α-Ga2O3 film. Background Art

[0002] A mist chemical vapor deposition method (Mist CVD, hereinafter also referred to as "mist CVD method") for forming a thin film on a substrate using an atomized mist raw material has been developed and used for the production of oxide semiconductor films and the like (Patent Documents 1 and 2).

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2013-028480

[0006] Patent Document 2: Japanese Patent Application Publication No. 2014-063973

[0007] Patent Document 3: Japanese Patent Application Publication No. 2021-136445 Summary of the invention

[0008] 1. Technical issues to be resolved

[0009] However, in the mist CVD method, the mist will condense in the film forming chamber, or the products attached to the wall will detach and become free, becoming a source of particle generation. In addition, since the mist CVD method is essentially a film forming method in which mist = particles are supplied, no special attention is paid to particles. In addition, there has been no established method for atomizing raw materials for forming high-quality films. The problem is that a large number of particles due to the quality of the raw material mist mentioned above are attached to the produced film. In addition, it is known that when the film forming speed is increased, if the mist supply is increased, this particle attachment will become more significant, and the technical problem lies in the balance between film quality and productivity.

[0010] In order to solve the above technical problems, a method for suppressing particle generation by controlling the atomization method is disclosed in, for example, Patent Document 3. However, if the film forming time is prolonged as the film thickness increases, the mist will condense in the film forming chamber, or the products attached to the wall of the film forming chamber will detach and become free, thus becoming a new source of particle generation.

[0011] Furthermore, in order to disperse the mist in the film forming chamber, the film forming chamber is usually set to a negative pressure. Therefore, a lot of external air flows in from outside the film forming chamber, and there is a problem that the film is contaminated by particles in the external air.

[0012] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a film forming method and a film forming apparatus for forming a high-quality crystalline oxide film with a significantly reduced particle density on the film surface.

[0013] In addition, an object of the present invention is to provide a high-quality α-Ga2O3 film with significantly reduced particle density on the film surface.

[0014] (II) Technical solution

[0015] The present invention is completed in order to achieve the above-mentioned purpose, and provides a film forming method, which is a film forming method for a crystalline oxide film formed by a mist CVD method by supplying a carrier gas and mist to a heated substrate in a film forming portion covered by a partition wall, and is characterized in that, at least during the heating of the substrate, a gas other than the carrier gas is transported into the film forming portion.

[0016] According to this film forming method, a high-quality semiconductor film with significantly reduced particle density on the film surface can be obtained.

[0017] At this time, it is preferred that when the mist is not supplied, the density of particles having a particle size of 0.3 μm in the film forming section be 100,000 / m 3 the following.

[0018] According to this film forming method, a high-quality semiconductor film can be obtained in which the particle density on the film surface is more significantly reduced.

[0019] At this time, air is preferably used as a gas other than the carrier gas.

[0020] According to this film forming method, a crystalline oxide film can be produced at low cost, and the safety during the production of the crystalline oxide film is also excellent.

[0021] The present invention is completed in order to achieve the above-mentioned object, and provides a film forming method, which is a film forming method of a crystalline oxide film formed by a mist CVD method by supplying a carrier gas and mist to a heated substrate in a film forming section covered by a partition wall, characterized in that at least when the mist is not supplied, the density of particles with a particle size of 0.3 μm or more in the film forming section is 100,000 / m 3 the following.

[0022] In this case, it is preferable that an exhaust section is provided so as to surround the film forming section, and the film forming section is exhausted through the exhaust section.

[0023] According to this film forming method, the manufacturing apparatus can be simplified and the safety is excellent.

[0024] At this time, it is preferable that the exhaust flow rate of the exhaust gas from the exhaust portion is larger than the flow rate of the carrier gas.

[0025] According to this film formation method, a high-quality semiconductor film can be obtained which has better safety and has not only a significantly reduced particle density but also a significantly reduced surface defect density.

[0026] At this time, a substrate having a diameter of 4 inches (100 mm) to 8 inches (200 mm) is preferably used as the substrate.

[0027] According to this film forming method, even for a large-area substrate, a high-quality semiconductor film with a more significantly reduced particle density on the film surface can be obtained.

[0028] The present invention is completed in order to achieve the above-mentioned purpose, and provides a film forming device, which is a film forming device having a film forming part covered by a partition wall, a carrier gas supplying part, and an atomizing part that generates mist, and supplies carrier gas and mist to the film forming part to form a film. The film forming device is characterized in that a gas conveying part for conveying a gas other than the carrier gas is provided in the film forming part.

[0029] According to this film forming apparatus, the above film forming method can be implemented, and a high-quality semiconductor film with significantly reduced particle density on the film surface can be obtained. In addition, the crystalline oxide film can be produced at low cost, and the safety during the production of the crystalline oxide film is also excellent.

[0030] In this case, it is preferable that a filter is provided in the gas transport unit.

[0031] According to such a film forming apparatus, a high-quality semiconductor film can be obtained in which the particle density on the film surface is more significantly reduced.

[0032] In this case, it is preferable that an exhaust section is provided so as to surround the film forming section, and the film forming section is exhausted through the exhaust section.

[0033] According to this film forming apparatus, simplification is possible and safety is excellent.

[0034] In this case, it is preferable that the gas transport unit transports air as a gas other than the carrier gas.

[0035] According to such a film forming apparatus, a crystalline oxide film can be manufactured at low cost, and safety is excellent when manufacturing the crystalline oxide film.

[0036] The present invention is completed in order to achieve the above-mentioned object, and provides an α-Ga2O3 film, characterized in that the film thickness deviation is less than 3.3%, and the particle size on the film confirmed by an optical microscope is 29 / cm 2 the following.

[0037] According to this α-Ga2O3 film, the film thickness distribution is excellent and the mixing of foreign matter into the film is suppressed, so it is a high-quality film suitable for semiconductor device manufacturing with a significantly reduced particle density on the film surface.

[0038] In this case, the half-value width of the rocking curve of the (006) plane obtained by X-ray diffraction is preferably 8 seconds or less.

[0039] According to this α-Ga2O3 film, the crystallinity becomes good.

[0040] At this time, the diameter of the α-Ga2O3 film is preferably 4 inches (100 mm) to 8 inches (200 mm).

[0041] According to this α-Ga2O3 film, even for a large-area substrate, the particle density on the film surface is more significantly reduced and of high quality.

[0042] (III) Beneficial effects

[0043] As described above, according to the film forming method of the present invention, a high-quality crystalline oxide film with a significantly reduced particle density on the film surface can be obtained.

[0044] According to the film forming apparatus of the present invention, a high-quality crystalline oxide film with a significantly reduced particle density on the film surface can be obtained.

[0045] The α-Ga2O3 film of the present invention is of high quality with a significantly reduced particle density on the film surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 This is a schematic structural diagram showing an example of the film forming apparatus of the present invention.

[0047] Figure 2 This is a schematic structural diagram showing an example of a semiconductor device using a stacked structure produced by the film forming method and film forming apparatus of the present invention.

[0048] Figure 3 This is a schematic structural diagram showing another example of the film forming section of the film forming apparatus of the present invention.

[0049] Figure 4 This is a schematic structural diagram showing still another example of the film forming section of the film forming apparatus of the present invention.

[0050] Figure 5 This is a schematic structural diagram showing still another example of the film forming section of the film forming apparatus of the present invention.

[0051] Figure 6 This is a schematic structural diagram showing still another example of the film forming section of the film forming apparatus of the present invention. DETAILED DESCRIPTION

[0052] Hereinafter, the present invention will be described in detail, but the present invention is not limited thereto.

[0053] As described above, a film forming method and a film forming apparatus are desired that can obtain a high-quality crystalline oxide film with a significantly reduced particle density on the film surface.

[0054] The inventors of the present application have repeatedly conducted in-depth studies on the above-mentioned technical problems and found that a high-quality crystalline oxide film with significantly reduced particle density on the film surface can be obtained by a film-forming method, and a high-quality crystalline oxide film with significantly reduced particle density on the film surface can be obtained by a film-forming device, thereby completing the present invention, wherein the film-forming method is: in a film-forming portion covered by a partition wall, a carrier gas and mist are supplied to a heated substrate, thereby forming a crystalline oxide film by a mist CVD method, characterized in that at least during the heating of the substrate, a gas other than the carrier gas is transported into the film-forming portion; or in a film-forming portion covered by a partition wall, a carrier gas and mist are supplied to a heated substrate, thereby forming a crystalline oxide film by a mist CVD method, characterized in that at least when no mist is supplied, the density of particles with a particle size of 0.3 μm or more in the film-forming portion is made 100,000 / m 3 Hereinafter, the film forming device is a film forming device having a film forming part covered by a partition wall, a carrier gas supplying part, and an atomizing part for generating mist, and supplying carrier gas and mist to the film forming part to form a film, and is characterized in that a gas conveying part for conveying a gas other than the carrier gas is provided in the film forming part.

[0055] In addition, as described above, a high-quality α-Ga2O3 film is sought with a significantly reduced particle density on the film surface.

[0056] The inventors of the present application have repeatedly conducted in-depth research on the above technical problems, and as a result, have found a high-quality α-Ga2O3 film with significantly reduced particle density on the film surface, thereby completing the present invention. The α-Ga2O3 film is characterized in that the film thickness deviation is less than 3.3%, and the particle density on the film confirmed by an optical microscope is 29 / cm 2 the following.

[0057] (First embodiment of the present invention)

[0058] (Film forming device)

[0059] Hereinafter, a film forming method and a film forming apparatus according to a first embodiment of the present invention will be described.

[0060] Figure 1 This is a schematic structural diagram showing an example of the film forming apparatus of the present invention.

[0061] like Figure 1 As shown, the film forming apparatus 201 of the present invention includes a film forming section 215 surrounded by a partition wall (film forming chamber) 207 , a carrier gas supply section 230 , and an atomizing section 220 for generating mist.

[0062] (Atomization part)

[0063] The atomizing unit 220 generates mist by atomizing the raw material solution 204 a.

[0064] The mist in the present invention is a general term for liquid particles dispersed in a gas, including particles called mist, droplets, and the like.

[0065] The atomizing means is not particularly limited as long as it can atomize the raw material solution 204a, and may be a known atomizing means, but an atomizing means based on ultrasonic vibration is preferably used because atomization can be performed more stably.

[0066] like Figure 1 As shown, the atomizing unit 220 includes a mist generating source 204 containing a raw material solution 204a, a container 205 containing a medium capable of transmitting ultrasonic vibrations, such as water 205a, and an ultrasonic vibrator 206 mounted on the bottom surface of the container 205. In detail, the mist generating source 204, which is composed of a container containing the raw material solution 204a, is stored in the container 205 containing water 205a using a support body (not shown). The ultrasonic vibrator 206 is provided at the bottom of the container 205, and the ultrasonic vibrator 206 is connected to the oscillator 216, so that when the oscillator 216 is operated, the ultrasonic vibrator 206 vibrates, and the ultrasonic wave is transmitted to the mist generating source 204 through the water 205a, and the raw material solution 204a is atomized.

[0067] (Raw material solution)

[0068] As long as the raw material solution 204a can be atomized, the material contained in the solution is not particularly limited, and can be an inorganic material or an organic material. As a material, a metal or a metal compound is suitable for use, for example, a material containing one or more metals selected from gallium, iron, indium, aluminum, vanadium, titanium, chromium, rhodium, nickel and cobalt can also be used. As the raw material solution as described above, it is suitable to use a solution in which the metal is dissolved or dispersed in an organic solvent or water in the form of a complex or salt. As the form of the salt, for example, halides such as metal chloride salts, metal bromides, and metal iodides can be listed. In addition, a solution in which the above-mentioned metal is dissolved in hydrogen halides such as hydrobromic acid, hydrochloric acid, and hydroiodic acid can also be used as a salt solution. As the form of the complex, for example, acetylacetonate complexes, carbonyl complexes, ammine complexes, hydride complexes, etc. can be listed. By mixing acetylacetone in the solution of the above-mentioned salt, an acetylacetonate complex can also be formed. The metal concentration in the raw material solution 204a is not particularly limited, and can be set to 0.005 to 1 mol / L. The temperature during mixing and dissolving is preferably 20°C or higher.

[0069] Additives such as hydrohalic acid or oxidizing agent may be mixed in the raw material solution 204a. Examples of the hydrohalic acid include hydrobromic acid, hydrochloric acid, and hydroiodic acid. Among them, hydrobromic acid and hydroiodic acid are preferred because they can achieve a higher film forming rate. Examples of the oxidizing agent include peroxides such as hydrogen peroxide (H2O2), sodium peroxide (Na2O2), barium peroxide (BaO2), and benzoyl peroxide (C6H5CO)2O2, and organic peroxides such as hypochlorous acid (HClO), perchloric acid, nitric acid, ozone water, peracetic acid, or nitrobenzene.

[0070] The raw material solution 204a may also contain a dopant source. The dopant source is not particularly limited. For example, n-type dopant sources such as tin, germanium, silicon, titanium, zirconium, vanadium, or niobium, or p-type dopant sources such as copper, silver, iridium, rhodium, and magnesium may be cited.

[0071] (Carrier gas supply unit)

[0072] The carrier gas supply unit 230 supplies a carrier gas for carrying mist.

[0073] like Figure 1 As shown, the carrier gas supply unit 230 has a carrier gas source 202a for supplying carrier gas, and is provided with a flow control valve 203a for adjusting the flow rate of the carrier gas sent from the carrier gas source 202a. In addition, it is provided with a dilution carrier gas source 202b and a flow control valve 203b for adjusting the flow rate of the dilution carrier gas sent from the dilution carrier gas source 202b. Thus, in addition to the carrier gas, the dilution carrier gas can be supplied as needed. In addition, in the present invention, the sum of the carrier gas flow rate and the dilution carrier gas flow rate is referred to as the total carrier gas flow rate.

[0074] The type of carrier gas is not particularly limited and can be appropriately selected according to the film-forming material. For example, inert gases such as oxygen, ozone, nitrogen or argon, or reducing gases such as hydrogen or forming gas (forming gas) can be listed. In addition, the type of carrier gas can be one or more. For example, as the second carrier gas, a dilution gas obtained by diluting the same gas as the first carrier gas (for example, diluting 10 times) with a gas other than the same gas as the first carrier gas can be further used, and air can also be used. The flow rate of the total carrier gas is not particularly limited. For example, when a film is formed on a substrate with a diameter of 2 inches (about 50 mm), it is preferred to set the flow rate of the total carrier gas to 0.05~50NL / minute, and more preferably to 5~20NL / minute. In addition, NL is a value obtained by converting the volume of the gas into a standard state (0°C, 1 standard atmospheric pressure).

[0075] (Supply pipe)

[0076] The supply pipe 209 connects the atomizing unit 220 and the film forming unit 215 and transports the mist by the carrier gas. The mist is generated from the mist generation source 204 of the atomizing unit 220 , passed through the supply pipe 209 and transported by the carrier gas, and supplied to the film forming unit 215 .

[0077] For example, a quartz tube, a glass tube, a resin tube, etc. can be used as the supply tube 209. The front end of the supply tube 209 is a nozzle.

[0078] (Film Forming Department)

[0079] Figure 1 An example of a film forming unit of the film forming apparatus of the present invention is shown in FIG.

[0080] like Figure 1 As shown, the film forming section 215 is a portion substantially entirely covered by the partition wall (film forming chamber) 207 .

[0081] The so-called "substantially entirely covered" structure can be as follows Figure 1 , Figure 3 , Figure 4 As shown, the region including the substrate is completely covered by the partition wall, or Figure 5 , Figure 6 As shown, a part of the surface is open.

[0082] The material of the next wall (film forming chamber) 207 can be metal such as iron, aluminum, stainless steel, etc., or can be resin such as acrylic acid or vinyl chloride. If it is made of resin, the device is lightweight and the cost of the device is also cheap. If a transparent material is used, the situation during film formation can also be identified, which is easy to prevent the occurrence of device failure in advance.

[0083] A substrate 210 is provided in the partition wall (film forming chamber) 207, and a heater 208 for heating the substrate 210 is provided. The heater 208 may be, for example, Figure 1 As shown, it is arranged outside the next wall (film forming chamber) 207, for example, it can also be as shown Figure 5 , Figure 6 As shown, it is arranged inside the partition wall (film forming chamber) 207.

[0084] The film forming unit 207 can introduce a film forming gas (carrier gas) and mist supplied from a supply pipe 209 , and the carrier gas and the mist are ejected from a nozzle toward the substrate 210 , and the mist is thermally treated on the substrate 210 to form a film.

[0085] In addition, a top plate for rectifying the supplied mist on the substrate may be provided.

[0086] Furthermore, a gas transport unit 501 for transporting a gas other than a carrier gas is provided in the partition wall (film forming chamber) 207 .

[0087] (Gas Transportation Department)

[0088] In the present invention, a gas delivery unit 501 is connected to deliver a gas other than the carrier gas, such as air, to the next door (film forming chamber) 207, which is different from the carrier gas used for film formation. The delivered gas is not particularly limited, and in addition to air, inert gas can be listed, and air is particularly preferred. The gas delivery unit 501 can be as follows: Figure 1 As shown, it is located vertically above the substrate 210, and can also be as shown Figure 3 As shown, the gas delivery unit 501 is located on the side of the substrate 210. A filter may be provided in the gas delivery unit 501. By using a high-performance filter such as HEPA, the cleanliness in the film forming unit can be improved. By delivering gas from the gas delivery unit 501, the density of particles in the gas with a particle size of 0.3 μm or more in the film forming unit can be 100,000 / m 3 Since the particle density is as low as possible, the lower limit is 0 / m 3 . In addition, the particles in the gas at this time can be measured using a commercially available particle counter that uses a light scattering method. Although a light interception method can also be used, a light scattering method is more commonly used and is preferred. A particle counter can be always available in the film forming device, or a mechanism can be provided to continuously monitor the particle density in the film forming section and then determine whether a film can be formed based on the measured particle density. The upper limit of the particle diameter is not particularly limited, for example, it is 1000μm.

[0089] (Exhaust port)

[0090] The partition wall (film forming chamber) 207 may be provided with an exhaust port 212 for exhausting gas. Figure 5 and Figure 6 In the example, the open surface of the adjacent wall can be regarded as a larger exhaust port.

[0091] (Exhaust section)

[0092] An exhaust portion may be provided so as to surround the partition wall (film forming chamber) 207 . Figure 4~Figure 6 In the example shown, the exhaust portion 511 surrounds the partition wall (film forming chamber) 207. Figure 6 As shown, a part of the next wall (film forming chamber) 207 may be in common with a part of the outer wall of the exhaust section 511. The exhaust section 511 has one or more exhaust ports 512 connected to a fan or the like to force exhaust inside thereof. From the purpose, the exhaust section 511 only needs to exhaust and does not need to be completely sealed.

[0093] (Substrate)

[0094] The substrate 210 is a base substrate for forming a crystalline oxide film. As long as it becomes a support body of the crystalline oxide film, it is not particularly limited. The material is not particularly limited, and a known substrate can be used, which can be an organic compound or an inorganic compound. For example, polysulfone, polyethersulfone, polyphenylene sulfide, polyetheretherketone, polyimide, polyetherimide, fluororesin, metals such as iron or aluminum, stainless steel, gold, quartz, glass, calcium carbonate, gallium oxide, ZnO, etc. can be listed. In addition, single crystal substrates such as silicon, sapphire, lithium tantalate, lithium niobate, SiC, GaN, iron oxide, chromium oxide, etc. can be listed. In the present invention, the single crystal substrate as described above is ideal. Thus, a crystalline oxide film of better quality can be obtained. In particular, sapphire substrates, lithium tantalate substrates, and lithium niobate substrates are relatively cheap and industrially advantageous.

[0095] The thickness of the substrate 210 is preferably 100 to 5000 μm. Within this range, handling is easy, and thermal resistance can be suppressed during film formation, so that a high-quality film can be easily obtained.

[0096] The size of the substrate 210 is not particularly limited, as long as the area of ​​the substrate is 100 mm 2 If the substrate is 4 inches (100 mm) to 8 inches (200 mm) in diameter or more, a large-area film with good crystallinity can be obtained, which is preferred. In addition, if the diameter of the substrate is 4 inches (100 mm) to 8 inches (200 mm), it is easy to process the obtained crystalline oxide film using existing processing equipment, which is industrially advantageous when manufacturing semiconductor devices. In addition, it has a large area and excellent film thickness distribution, and has excellent semiconductor properties when suitable for semiconductor devices. For example, when semiconductor devices such as power semiconductor devices are manufactured from such a crystalline oxide film, the breakdown voltage yield of a batch of products containing more than two of the semiconductor devices can be made to be 75% or more.

[0097] There may be other layers between the substrate 210 and the crystalline oxide film. Other layers refer to layers having a composition different from that of the substrate and the outermost crystalline oxide film, and are also called buffer layers. The buffer layer may be any one of an oxide semiconductor film, an insulating film, a metal film, and the like. As materials, for example, Al2O3, Ga2O3, Cr2O3, Fe2O3, In2O3, Rh2O3, V2O3, Ti2O3, Ir2O3, and the like may be appropriately used. The thickness of the buffer layer is preferably 0.1 μm to 2 μm.

[0098] Figure 1 In the embodiment, the substrate 210 is disposed on the bottom surface of the partition wall (film forming chamber) 207 and arranged face-up. However, the substrate 210 may be disposed on the upper surface of the partition wall (film forming chamber) 207 and arranged face-down.

[0099] Furthermore, the heater 208 or the nozzle may be connected to a transport mechanism to enable a reciprocating motion or a rotating motion. By performing such a moving operation during film formation, the uniformity of the obtained film is improved.

[0100] (Film Forming Method)

[0101] The film forming method of the present invention will be described.

[0102] The film forming method of the present invention is a film forming method for forming a crystalline oxide film by supplying a carrier gas and mist to a heated substrate 210 in a film forming section 215 covered by an adjacent wall (film forming chamber) 207, thereby utilizing a mist CVD method. The film forming method is a film forming method in which a gas other than the carrier gas is transported into the film forming section 215 at least during the heating of the substrate 210.

[0103] In more detail, it includes: a mist generating process of atomizing a raw material solution in the atomizing section 220 to generate mist; a carrier gas supplying process of supplying a carrier gas for transporting the mist to the atomizing section 220; a transporting process of transporting the mist from the atomizing section 220 to the film forming section 215 via a supply pipe 209 connecting the atomizing section 220 and the film forming section 215 by the carrier gas; and a film forming process of heat-treating the transported mist to form a film on a base substrate (substrate) 210.

[0104] First, the substrate 210 is placed in the film forming section 215 which is substantially entirely covered by the partition wall (film forming chamber) 207, and the heater 208 is operated. At least during the heating of the substrate, a gas other than the carrier gas is transported. The gas transport flow rate can be set to 20 to 10,000 NL / min. For example, air can be transported from the gas transport section 501. Preferably, at least when no mist is supplied, the density of particles with a particle size of 0.3 μm or more in the film forming section 215 is 100,000 / m 3In addition, for example, nitrogen gas may be supplied from the gas supply unit 501. At this time, a diffuser (diffuser plate) or the like may be provided so that the gas is widely dispersed in the film forming chamber.

[0105] In addition, the cleanliness in the film forming section 215 can be improved by delivering a large amount of carrier gas, but the flow rate of the carrier gas is usually small and the effect is limited. In addition, the carrier gas is usually pressurized to a higher level than necessary or highly purified, and flowing a large amount of it will increase the cost.

[0106] The exhaust may be forced to be exhausted from the exhaust port 212. At this time, it is desirable to make the exhaust flow rate from the exhaust port 212 the same as the flow rate from the gas delivery unit 501 or to make the exhaust flow rate from the exhaust port 212 smaller than the flow rate from the gas delivery unit 501. This is because if the exhaust flow rate is large, external gas will flow into the film forming unit 207, and the cleanliness will be reduced.

[0107] Further, if Figure 4~Figure 6 When the exhaust section 511 is provided as shown, the exhaust fan or the like can be operated to exhaust the exhaust section 511. The pressure inside the exhaust section 511 (excluding the area of ​​the next wall (film forming chamber) 207) is lower than the pressure outside the exhaust section 511, and the pressure difference is preferably about 0.1 to 100 Pa.

[0108] Furthermore, it is preferable to make the exhaust flow rate of the exhaust gas from the exhaust unit 511 larger than the flow rate of the carrier gas. This can provide a high-quality semiconductor film with better safety and significantly reduced particle density and surface defect density.

[0109] (Mist generation process)

[0110] In the mist generation step, the raw material solution 204a is contained in the mist generation source 204, and the ultrasonic vibrator 206 is vibrated. The vibration is propagated to the raw material solution 204a through the water 205a, thereby atomizing the raw material solution 204a to generate mist.

[0111] (Carrier gas supply process)

[0112] In the carrier gas supplying step, a carrier gas for transporting the mist and a carrier gas for dilution are supplied to the atomizing unit 220 .

[0113] In addition, open the flow regulating valves 203a and 203b, and supply the carrier gas and the dilution carrier gas from the carrier gas source 202a and the dilution carrier gas source 202b to the film forming section 215. After the atmosphere of the film forming section 215 is fully replaced with the carrier gas and the dilution carrier gas, adjust the flow rates of the carrier gas and the dilution carrier gas respectively.

[0114] (Transportation process)

[0115] In the transport process, the mist is transported from the atomizing section 220 to the nozzle in the film forming section 215 by the carrier gas or the dilution carrier gas via the supply pipe 209 connecting the atomizing section 220 and the film forming section 215 .

[0116] (Film Forming Process)

[0117] In the film forming step, the mist and carrier gas transported to the nozzle are ejected toward the substrate 210 , and the substrate 210 is heated to generate a thermal reaction, thereby forming a film on the surface of the substrate 210 .

[0118] In the film forming process, it is not necessary to transport the gas other than the carrier gas. If the film is formed while transporting the gas other than the carrier gas, the particle density on the obtained film can be further reduced. In addition, since the mixing of foreign matter in the film is suppressed, the crystallinity is further improved. In addition, since the mist is appropriately dispersed on the substrate, the film thickness distribution is also improved.

[0119] Alternatively, the substrate 210 or the nozzle may be connected to a transport mechanism so as to be moved in a reciprocating motion or a rotating motion during film formation. By performing such a moving operation, the uniformity of the obtained film can be further improved.

[0120] The thermal reaction of the mist also depends on the temperature of the environment around the substrate. Therefore, it is ideal that the temperature of the nozzle or the inner wall of the film forming unit 215 is higher than room temperature. This can stabilize the thermal reaction. For example, the nozzle temperature can be set to 50 to 250°C.

[0121] In addition, the thermal reaction can be carried out in any of the following atmospheres: non-oxygen atmosphere, reducing gas atmosphere, air atmosphere, and oxygen atmosphere, and can be appropriately set according to the film to be formed. In addition, the reaction pressure can be carried out under any of the following conditions: atmospheric pressure, pressurized, or reduced pressure, but film formation under atmospheric pressure is preferred because the device configuration can be simplified.

[0122] (Heat Treatment)

[0123] In addition, the laminated structure produced by the film forming method and film forming apparatus of the present invention can be heat treated at 200 to 600° C. Thus, unreacted species in the film can be further removed to obtain a higher quality laminated structure. The heat treatment can be carried out in air or oxygen atmosphere, or in an inert gas atmosphere such as nitrogen or argon. The heat treatment time can be appropriately determined, for example, it can be set to 5 to 240 minutes.

[0124] (peel off)

[0125] In the stacked structure produced by the film forming method and film forming apparatus of the present invention, the crystalline oxide film can be peeled off from the base substrate. The peeling means is not particularly limited and can be a known means. As the method of peeling means, for example, a means of peeling by applying mechanical impact, a means of peeling by applying heat and utilizing thermal stress, a means of peeling by applying vibration such as ultrasound, a means of peeling by etching, etc. can be listed. By such peeling, a crystalline oxide film can be obtained in the form of a self-supporting film.

[0126] (Crystalline oxide film)

[0127] Regarding the crystalline oxide film produced by the film forming method and film forming apparatus of the present invention, the density of particles having a diameter of 0.3 μm or more on the surface of the crystalline oxide film is 50 / cm 2 When a semiconductor device is manufactured based on a crystalline oxide film, particles with a diameter of 0.3 μm or more have a significant effect on the characteristics. A crystalline oxide film having a density of particles with a diameter of 0.3 μm or more is of high quality suitable for manufacturing semiconductor devices.

[0128] In addition, the "particles on the substrate" in the present invention include particles mixed in the crystalline oxide film and integrated with the film and particles attached to the surface of the crystalline oxide film in the form of foreign matter, and refer to particles observed in the form of particles when observing the surface of the film.

[0129] In addition, the diameter of the particles on the substrate is a value based on the size of the particles measured by a light scattering particle measuring machine. The size of the particles is determined by calibrating the measuring machine with standard particles of multiple sizes. That is, it is a value classified by comparing the measured value when the particles are measured by the measuring machine with the measured value when the standard particles are measured. The particles on the surface of the crystalline oxide film can be measured, for example, using a laser scattering particle counter. In addition, the film surface can also be observed using an optical microscope and counted by size. For example, if it is set to a dark field and the magnification is set to 50 times, etc., it is possible to observe particles on the substrate of about 0.3 to 100 μm.

[0130] In general, a crystalline oxide film is composed of a metal and oxygen. In the crystalline oxide film of the present invention, gallium is preferably used as the main metal component. In the present invention, "gallium oxide is used as the main component" means that 50 to 100% of the metal component is gallium. As a metal component other than gallium, for example, one or more metals selected from iron, indium, aluminum, vanadium, titanium, chromium, rhodium, iridium, nickel and cobalt may be included.

[0131] The crystalline oxide film may also contain doping elements. Examples include, but are not particularly limited to, n-type dopants such as tin, germanium, silicon, titanium, zirconium, vanadium, or niobium, and p-type dopants such as copper, silver, tin, iridium, rhodium, and magnesium. The concentration of the dopant may be, for example, about 1×10 16 / cm 3 ~1×10 22 / cm 3 , can be set to about 1×10 17 / cm 3 The following low concentrations can also be set to about 1×10 20 / cm 3 Above high concentration.

[0132] The crystal structure of the crystalline oxide film is not particularly limited, and may be a β-gallium oxide structure, a corundum structure, or an orthorhombic crystal. A plurality of crystal structures may be mixed, and may be polycrystalline, preferably a single crystal or a uniaxially oriented film. Whether it is a single crystal or a uniaxially oriented film can be confirmed using an X-ray diffraction device or an electron beam diffraction device. If the film is irradiated with X-rays or electron beams, a diffraction image that conforms to the crystal structure can be obtained. If it is uniaxially oriented, only specific peaks will appear. Thus, it can be judged as uniaxially oriented.

[0133] The film thickness of the crystalline oxide film is not particularly limited, but is preferably 0.1 μm or more. The upper limit is not particularly limited. For example, it can be 100 μm or less, preferably 50 μm or less, and can more preferably be 30 μm or less. The film thickness can be measured by a probe step profiler, a reflective spectroscopic film thickness meter, an ellipsometer, or by observing a cross section with a SEM or TEM, and any method can be used.

[0134] Such a crystalline oxide film can be obtained by forming a film using a mist CVD method using a mist CVD apparatus (film forming apparatus).

[0135] (α-Ga2O3 film)

[0136] As a specific example of a crystalline oxide film, an α-Ga 2 O 3 film can be exemplified.

[0137] The thickness deviation of the α-Ga2O3 film is less than 3.3%, and the particle size of the film confirmed by an optical microscope is 29 / cm 2 the following.

[0138] According to this α-Ga2O3 film, the film thickness distribution is excellent and the mixing of foreign matter into the film is suppressed, so it is a high-quality film suitable for semiconductor device manufacturing with a significantly reduced particle density on the film surface.

[0139] In addition, the smaller the film thickness deviation, the better, so the lower limit is preferably 0%. In addition, the fewer the particles on the film, the better, so the lower limit is preferably 0 / cm 2 .

[0140] The half-value width of the rocking curve of the (006) plane of the α-Ga2O3 film obtained by X-ray diffraction is preferably 8 seconds or less.

[0141] According to such an α-Ga2O3 film, the crystallinity becomes good. In addition, the smaller the half-value width is, the better, so the lower limit is preferably greater than 0 seconds.

[0142] In addition, the diameter of the α-Ga2O3 film is preferably 4 inches (100 mm) to 8 inches (200 mm).

[0143] According to this α-Ga2O3 film, even for a large-area substrate, the particle density on the film surface is more significantly reduced and of high quality.

[0144] (Formation of buffer layer)

[0145] A buffer layer can be appropriately provided between the substrate and the crystalline oxide film. The method for forming the buffer layer is not particularly limited, and a known method such as sputtering and evaporation can be used to form a film. When the mist CVD method is used, it can be formed by simply changing the raw material solution, which is simple. Specifically, a solution 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 can be appropriately used as a raw material aqueous solution. As the form of the complex, for example, acetylacetonate complexes, carbonyl complexes, ammonia complexes, hydride complexes, etc. can be listed. As the form of the salt, for example, chloride metal salts, bromide metal salts, iodide metal salts, etc. can be listed. In addition, a solution in which the above metals are dissolved in hydrobromic acid, hydrochloric acid, hydroiodic acid, etc. can be used as an aqueous solution of the salt. At this time, the solute concentration is preferably 0.005~1mol / L, and the dissolution temperature is preferably set to above 20°C. For other conditions, the buffer layer can be formed in the same manner as above. The buffer layer is formed into a predetermined thickness and then film-formed by the above-mentioned method.

[0146] As a special case of the buffer layer formation method, there is a case where the same material as the crystalline oxide film is used. In this case, the film formation temperature of the buffer layer can be made higher than the film formation temperature of the crystalline oxide film. For example, the film formation temperature of the buffer layer can be set to 450°C and the film formation temperature of the crystalline oxide film can be set to 400°C, or the buffer layer can be set to 500°C and the crystalline oxide film can be set to 450°C. By doing so, the crystallinity of the crystalline oxide film is further improved.

[0147] (Semiconductor Device)

[0148] Figure 2 This is a schematic structural diagram showing an example of a semiconductor device using a stacked structure including a crystalline oxide film produced by the film forming method and film forming apparatus of the present invention.

[0149] like Figure 2 As shown, a semiconductor device 100 using a stacked structure including a crystalline oxide film produced by the film forming method and film forming apparatus of the present invention has a stacked structure 110 in which a crystalline oxide film 103 is stacked on a base substrate 101, and the crystalline oxide film 103 is stacked on an insulating film 103a and a conductive film 103b is stacked. In addition, a gate insulating film 105 is formed on the conductive film 103b. A gate 107 is formed on the gate insulating film 105. In addition, a source and a drain 109 are formed on the conductive film 103b in a manner of sandwiching the gate 107. According to this structure, by applying a gate voltage to the gate 107, it is possible to control the depletion layer formed in the conductive film 103b, and transistor operation (FET device) becomes possible.

[0150] The semiconductor device 100 can be used for transistors such as MIS, HEMT, IGBT, or TFT, Schottky barrier diodes using semiconductor-metal junctions, PN or PIN diodes formed by combining with other P layers, and light-receiving and light-emitting elements. The crystalline oxide film formed by the film forming method and film forming device of the present invention can be a high-quality crystalline film, which can be useful for improving the characteristics of the above-mentioned devices.

[0151] (Second embodiment of the present invention)

[0152] Hereinafter, a film forming apparatus according to a second embodiment of the present invention will be described.

[0153] Figure 3 This is a schematic structural diagram showing another example of the film forming section of the film forming apparatus of the present invention.

[0154] like Figure 3 As shown, the film forming apparatus according to the second embodiment of the present invention has the same configuration as the film forming apparatus according to the first embodiment of the present invention, except that the position of the gas transport unit 501 is changed from the top plate to the side.

[0155] With this configuration, the gas of the gas transport unit 501 can reduce the number of particles in the gas in the film forming unit, and can form a high-quality crystal film.

[0156] (Third Embodiment of the Present Invention)

[0157] Hereinafter, a film forming apparatus according to a third embodiment of the present invention will be described.

[0158] Figure 4This is a schematic structural diagram showing still another example of the film forming section of the film forming apparatus of the present invention.

[0159] like Figure 4 As shown, the film forming device of the third embodiment of the present invention has the same structure as the film forming device of the first embodiment of the present invention, except that the exhaust part 511 is provided in a manner to surround the adjacent wall (film forming chamber) 207, and exhaust is performed from the adjacent wall (film forming chamber) 207 via the exhaust part 511.

[0160] With this configuration, the gas in the gas delivery unit 501 can also reduce the number of particles in the gas in the film forming unit, and can produce a high-quality crystal film. In particular, by making the film forming unit positively pressurized and the exhaust unit negatively pressurized, the number of particles in the gas in the film forming unit can be further reduced.

[0161] (Fourth embodiment of the present invention)

[0162] Hereinafter, a film forming apparatus according to a fourth embodiment of the present invention will be described.

[0163] Figure 5 This is a schematic structural diagram showing still another example of the film forming section of the film forming apparatus of the present invention.

[0164] like Figure 5 As shown, the film forming apparatus of the fourth embodiment of the present invention has the same structure as the film forming apparatus of the third embodiment of the present invention, except that the partition wall (film forming chamber) 207 has no bottom and the bottom portion is set as a huge exhaust port.

[0165] With this configuration, the gas of the gas transport unit 501 can also reduce the number of particles in the gas in the film forming unit, and can form a high-quality crystal film. In particular, the large exhaust port can further reduce the number of particles in the gas in the film forming unit.

[0166] (Fifth embodiment of the present invention)

[0167] Hereinafter, a film forming apparatus according to a fifth embodiment of the present invention will be described.

[0168] Figure 6 This is a schematic structural diagram showing still another example of the film forming section of the film forming apparatus of the present invention.

[0169] like Figure 6 As shown, the film forming apparatus according to the fifth embodiment of the present invention has the same structure as the film forming apparatus according to the fourth embodiment of the present invention, except that the partition wall (film forming chamber) 207 and the ceiling plate of the exhaust portion 511 are common.

[0170] With this configuration, the gas of the gas transport unit 501 can also reduce the number of particles in the gas within the film forming unit, and a high-quality crystal film can be formed.

[0171] Example

[0172] Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited thereto.

[0173] [Example 1]

[0174] Figure 1 In the film forming apparatus 201 shown, film formation is performed in a partition wall (film forming chamber) 207 .

[0175] The film forming device 201 includes a carrier gas source 202a for supplying a carrier gas, a flow regulating valve 203a for regulating the flow rate of the carrier gas sent from the carrier gas source 202a, a dilution carrier gas source 202b for supplying a dilution carrier gas, a flow regulating valve 203b for regulating the flow rate of the dilution carrier gas sent from the dilution carrier gas source 202b, a mist generating source 204 for containing a raw material solution 204a, a container 205 containing water 205a, and an ultrasonic vibrator 206 installed on the bottom surface of the container 205.

[0176] The next door (film forming chamber) 207 is equipped with a heater 208 and a quartz supply pipe 209 connected from the mist generating source 204 to the film forming section 215. A fan (gas transport section 501) is provided on the top plate of the next door (film forming chamber) 207 to supply clean air to the next door (film forming chamber) 207 through a HEPA filter.

[0177] The particle counter KC-31 manufactured by RION Co., Ltd. was used to measure the particles in the partition wall (film forming chamber) 207 during the gas delivery. The result showed that the number of particles with a particle size of 0.3 μm was 12830 / m 3 .

[0178] (Film Formation of Gallium Oxide Film)

[0179] Using this apparatus, a gallium oxide film was formed.

[0180] As the substrate 210 , a 4-inch (100 mm) c-plane sapphire substrate was prepared.

[0181] The substrate was placed in the partition wall (film forming chamber) 207, and the heater 208 was set to increase the temperature to 450°C. The substrate was left for 30 minutes to stabilize the temperature in the partition wall (film forming chamber) 207 including the nozzle.

[0182] The raw material solution 204a uses ultrapure water as a solvent and gallium bromide as a solute. The gallium concentration in the raw material solution is 0.1 mol / L.

[0183] The raw material solution 204 a is contained in the mist generation source 204 .

[0184] Next, the flow regulating valves 203a and 203b are opened to supply the carrier gas from the carrier gas sources 202a and 202b to the adjacent wall (film forming chamber) 207. After the atmosphere in the adjacent wall (film forming chamber) 207 is fully replaced with the carrier gas, the flow rates of the carrier gas and the dilution carrier gas are adjusted to 4 NL / min and 6 NL / min, respectively. Nitrogen gas is used as the carrier gas.

[0185] Next, the ultrasonic vibrator 206 is vibrated at 2.4 MHz, and the vibration is propagated to the raw material solution 204a through the water 205a, thereby atomizing the raw material solution 204a to generate mist. The mist is introduced into the next wall (film forming chamber) 207 through the supply pipe 209 by the carrier gas, and the mist is thermally reacted on the substrate 210, thereby forming a thin film of gallium oxide on the substrate 210. The film forming time is set to 30 minutes.

[0186] (evaluate)

[0187] Regarding the thin film formed on the substrate 210, it was confirmed by X-ray diffraction that α-Ga2O3 was formed.

[0188] The rocking curve of the (006) plane of α-Ga2O3 was measured, and the half-value width was 8 seconds, indicating extremely good crystallinity. In addition, when measuring the rocking curve, a four-crystal monochromator composed of two channel cut crystals was used to improve the monochromaticity of the X-rays, allowing for measurement with higher accuracy. Other measurement conditions are as follows.

[0189] [Measurement conditions]

[0190] Measurement device: SmartLab manufactured by Rigaku Corporation

[0191] Analysis conditions:

[0192] Measurement method: Rocking curve measurement (ω scan)

[0193] X-ray generating part: cathode Cu

[0194] : Output 45kV200mA

[0195] Detection unit: Semiconductor detector

[0196] Incident optics: Ge(220) groove monochromator

[0197] Solar slit Soller slit: Incident side -

[0198] : Light receiving side 5.0°

[0199] Slit: Incident side IS = 1 (mm)

[0200] :Length limit 0.5(mm)

[0201] :Light receiving side RS1=1RS2=1.1(mm)

[0202] Scanning conditions: Evaluation diffraction surface Ga2O3(006)

[0203] : Scanning axis ω

[0204] : Scanning mode step measurement

[0205] : Scanning range 18~22°

[0206] : Step length 0.005°

[0207] : Cumulative time 0.5 seconds / step

[0208] Next, the film thickness at 25 locations was measured using a reflection spectroscopic film thickness meter F50 manufactured by Filmetrics, INC. The average film thickness was 571 nm.

[0209] Furthermore, the film thickness deviation calculated by (maximum film thickness-minimum film thickness) / (maximum film thickness+minimum film thickness)×100(%) was 2.9%, which was good.

[0210] Using an optical microscope, 69 locations within the substrate surface were observed at a magnification of 50 times to check for particles on the film. No particles were found within the observation range. If the particle density was calculated from the observation range, it was 29 / cm 2 the following.

[0211] [Example 2]

[0212] In addition to making the next wall (film forming chamber) 207 Figure 3 Except for the configuration of , film formation and evaluation were carried out under the same conditions and methods as in Example 1.

[0213] [Example 3]

[0214] In addition to making the next wall (film forming chamber) 207 Figure 4Except for the structure and forced exhaust from the exhaust port 512, the film formation and evaluation were carried out under the same conditions and methods as in Example 1.

[0215] [Example 4]

[0216] In addition to making the next wall (film forming chamber) 207 Figure 5 Except for the composition, film formation and evaluation were carried out under the same conditions and methods as in Example 3.

[0217] [Example 5]

[0218] In addition to making the next wall (film forming chamber) 207 Figure 6 Except for the composition, film formation and evaluation were carried out under the same conditions and methods as in Example 3.

[0219] [Comparative Example]

[0220] Film formation and evaluation were performed under the same conditions and methods as in Example 1, except that a gas conveying unit (fan) was not provided on the ceiling of the partition wall (film forming chamber) 207 and air was not conveyed.

[0221] Table 1 shows the evaluation results of Examples 1 to 5 and Comparative Example.

[0222] [Table 1]

[0223]

[0224] As described above, Examples 1 to 5 of the present invention can reduce particles in the gas compared to the comparative example. At the same time, it can be seen that the particles attached to the film are drastically reduced.

[0225] In addition, compared with the comparative example, Examples 1 to 5 can also reduce the half-value width of the rocking curve. This shows that the crystallinity is also improved. It is presumed that this is because the mixing of foreign matter into the film is suppressed.

[0226] In addition, the film thickness distribution was also improved. The reason for this is considered to be that the mist was appropriately dispersed on the substrate by supplying air into the film forming chamber.

[0227] This specification includes the following protocols.

[0228] [1]: A film forming method, which is a method for forming a crystalline oxide film by supplying a carrier gas and mist to a heated substrate in a film forming section covered by a partition wall, thereby forming a film using a mist CVD method, characterized in that a gas other than the carrier gas is supplied to the film forming section at least during the heating of the substrate.

[0229] [2]: The film forming method according to [1] above, characterized in that when mist is not supplied, the density of particles with a particle size of 0.3 μm in the film forming section is set to 100,000 / m3 the following.

[0230] [3]: The film forming method according to [1] or [2] above, wherein air is used as a gas other than the carrier gas.

[0231] [4]: A film forming method for forming a crystalline oxide film by supplying a carrier gas and mist to a heated substrate in a film forming section covered by a partition wall, thereby forming the film by a mist CVD method, wherein:

[0232] At least when the mist is not supplied, the density of particles having a particle size of 0.3 μm or more in the film forming part is set to 100,000 / m 3 the following.

[0233] [5]: The film forming method according to any one of [1] to [4], characterized in that an exhaust section is provided to surround the film forming section, and exhaust is performed from the film forming section via the exhaust section.

[0234] [6]: The film forming method according to [5] above, wherein the exhaust flow rate of the exhaust gas from the exhaust section is made larger than the flow rate of the carrier gas.

[0235] [7]: The film forming method according to any one of the above [1] to [6], characterized in that a substrate with a diameter of 6 inches (100 mm) to 8 inches (200 mm) is used as the substrate.

[0236] [8]: A film forming device comprising a film forming section covered by a partition wall, a carrier gas supply section and an atomization section for generating mist, and supplying carrier gas and mist to the film forming section to form a film, wherein a gas conveying section for conveying a gas other than the carrier gas is provided in the film forming section.

[0237] [9]: The film forming device according to the above [8] is characterized in that a filter is provided in the gas transport section.

[0238]

[10] : The film forming apparatus according to [8] or [9], wherein an exhaust section is provided to surround the film forming section, and exhaust is performed from the film forming section via the exhaust section.

[0239]

[11] : The film forming apparatus according to any one of [8] to

[10] above, wherein the gas transport unit transports air as a gas other than the carrier gas.

[0240]

[12] : An α-Ga2O3 film characterized in that the film thickness deviation is less than 3.3% and the particle size on the film confirmed by optical microscopy is 29 / cm2 the following.

[0241]

[13] : The α-Ga2O3 film according to

[12] above, characterized in that the half-value width of the rocking curve of the (006) plane obtained based on X-ray diffraction is less than 8 seconds.

[0242]

[14] : An α-Ga2O3 film according to any one of

[12] or

[13] above, characterized in that the diameter is 4 inches (100 mm) to 8 inches (200 mm).

[0243] The present invention is not limited to the above-mentioned embodiments. The above-mentioned embodiments are merely examples, and any technical solution having substantially the same structure and having the same function and effect as the technical concept described in the claims of the present invention is included in the protection scope of the present invention.

Claims

1. A film forming method for forming a crystalline oxide film by supplying a carrier gas and mist to a heated substrate in a film forming section covered by a partition wall, wherein the crystalline oxide film is formed by a mist CVD method, wherein: At least during the heating of the substrate, a gas other than the carrier gas is supplied into the film forming section.

2. The film forming method according to claim 1, characterized in that: When the mist is not supplied, the density of particles having a particle size of 0.3 μm or more in the film forming part is set to 100,000 / m 3 the following.

3. The film forming method according to claim 1, characterized in that: Air was used as a gas other than the carrier gas.

4. A film forming method, which is a method for forming a crystalline oxide film by supplying a carrier gas and mist to a heated substrate in a film forming section covered by a partition wall, thereby forming a film by a mist CVD method, characterized in that: At least when the mist is not supplied, the density of particles having a particle size of 0.3 μm or more in the film forming part is set to 100,000 / m 3 the following.

5. The film forming method according to claim 1 or 4, characterized in that: An exhaust section is provided so as to surround the film forming section, and the film forming section is exhausted through the exhaust section.

6. The film forming method according to claim 5, characterized in that: The exhaust flow rate of the exhaust gas from the exhaust portion is set to be larger than the flow rate of the carrier gas.

7. The film forming method according to any one of claims 1 to 4, characterized in that: A substrate having a diameter of 4 inches (100 mm) to 8 inches (200 mm) is used as the substrate.

8. A film forming device comprising a film forming section covered by a partition wall, a carrier gas supply section, and an atomizing section for generating mist, and supplying carrier gas and mist to the film forming section to form a film, characterized in that: The film forming section is provided with a gas transport section for transporting a gas other than the carrier gas.

9. The film forming device according to claim 8, characterized in that: The gas conveying portion is provided with a filter.

10. The film forming device according to claim 8, characterized in that: An exhaust section is provided so as to surround the film forming section, and the film forming section is exhausted through the exhaust section.

11. The film forming device according to any one of claims 8 to 10, characterized in that: The gas delivery section delivers air as a gas other than the carrier gas.

12. An α-Ga2O3 film, characterized in that: The film thickness deviation was less than 3.3%, and the particles on the film confirmed by optical microscope were 29 / cm 2 the following.

13. The α-Ga2O3 film according to claim 12, characterized in that The half-value width of the rocking curve of the (006) plane obtained by X-ray diffraction was 8 seconds or less.

14. The α-Ga2O3 film according to any one of claims 12 or 13, characterized in that The diameter is 4 inches (100mm) ~ 8 inches (200mm).

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