JP2017010967A - Deposition method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a deposition method of forming a semiconductor film that is used for a semiconductor device, such as a diode and a transistor, and that is excellent in characteristics.SOLUTION: A raw material solution 4a containing metal and heavy hydrogen is atomized or made into droplets. Obtained mist 4b or droplets is transported to a substrate 10 installed in a deposition chamber 7, by a carrier gas. Next, thermal reaction of the mist 4b or the droplets is performed to deposit on the substrate 10 a semiconductor film that is excellent in semiconductor characteristics, especially in electric characteristics.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for forming a semiconductor film useful for a semiconductor device.

A semiconductor device using gallium oxide (Ga ₂ O ₃ ) having a large band gap has been attracting attention as a next-generation switching element that can achieve high breakdown voltage, low loss, and high heat resistance. Application is expected. Moreover, application as a light emitting / receiving device such as an LED or a sensor is also expected from a wide band gap. According to Non-Patent Document 1, the gallium oxide can control the band gap by mixing crystals of indium and aluminum, respectively, or in combination, and constitutes an extremely attractive material system as an InAlGaO-based semiconductor. . Here, the InAlGaO-based semiconductor means In _X Al _Y Ga Ga _Z O ₃ (0 ≦ X ≦ 2, 0 ≦ Y ≦ 2, 0 ≦ Z ≦ 2, X + Y + Z = 1.5 to 2.5). It can be overlooked as the same material system to be included.

  However, the conventional InAlGaO-based semiconductor has a high hydrogen concentration, and when the hydrogen concentration is high, a part of hydrogen becomes a donor or an acceptor due to a bond between an element contained in the oxide semiconductor and hydrogen, and electrons serving as carriers increase. There were problems such as being reduced.

  Patent Document 1 describes forming a film of gallium oxide having a corundum structure using the MBE method. However, such a method has many problems such as the corundum structure being broken, and the film formation itself is difficult. Moreover, the film obtained by the MBE method has a very high hydrogen concentration, and the electrical characteristics are not always satisfactory.

  In order to reduce the hydrogen concentration, it has been studied to perform an annealing treatment or a plasma treatment after the film formation. However, the hydrogen concentration cannot be reduced so much and the electrical characteristics are not always satisfactory.

  Patent Documents 2 to 4 describe forming a film of gallium oxide having a corundum structure using a mist CVD method. However, even if a gallium oxide having a corundum structure is formed using such a revolutionary method, the hydrogen concentration of the obtained film still remains high and is not always satisfactory.

  Non-Patent Document 2 describes forming a film of gallium oxide having a corundum structure using the HVPE method. However, the film thus obtained has a problem that the impurity concentration of halogen is high, and furthermore, it is difficult to obtain a film having sufficient electrical characteristics.

JP2013-58637A JP 2014-072533 A JP 2014-072517 A JP 2014-072463 A

Kentaro Kaneko, “Growth and Physical Properties of Corundum Structure Gallium Oxide Mixed Crystal Thin Films”, Kyoto University Doctoral Dissertation, March 2013 Yuichi Oshima et al., “Halide vapor phase epitaxy of twin-free α-Ga2O3 on sapphire (00001) substrates”, Applied Physics Express 8, 055501 (2015)

  An object of this invention is to provide the film-forming method which can form the semiconductor film excellent in the semiconductor characteristic.

As a result of intensive studies to achieve the above object, the present inventors have found that when a semiconductor film having a corundum structure is formed using deuterium by a mist CVD method, it has excellent semiconductor characteristics and is very useful for a semiconductor device. It has been found that a simple semiconductor film can be obtained, and it has been found that the use of such a method can solve the above-described conventional problems all at once.
Moreover, after obtaining the said knowledge, the present inventors repeated investigation further, and came to complete this invention.

That is, the present invention relates to the following inventions.
[1] A metal-containing raw material solution is atomized or formed into droplets, and the obtained mist or droplets are conveyed to a substrate installed in a film forming chamber with a carrier gas, and then the mist or droplets are reacted with heat. A method of forming a semiconductor film on the substrate, wherein the raw material solution contains deuterium.
[2] The film forming method according to [1], wherein the solvent of the raw material solution is heavy water.
[3] The film forming method according to [1] or [2], wherein an acid in which hydrogen atoms are substituted with deuterium is added to the raw material solution to atomize or form droplets.
[4] The film forming method according to any one of [1] to [3], wherein the raw material solution contains a dopant.
[5] The film forming method according to any one of [1] to [3], wherein the metal includes at least one of aluminum, indium, and gallium.
[6] The film forming method according to any one of [1] to [5], wherein the thermal reaction is performed at a temperature of 350 ° C. to 700 ° C.
[7] The film forming method according to any one of [1] to [6], wherein the substrate has a corundum structure.
[8] The film forming method according to any one of [1] to [7], wherein the substrate includes aluminum.
[9] The film forming method according to any one of [1] to [8], wherein the substrate includes an oxide.
[10] A semiconductor film formed by the film forming method according to any one of [1] to [9].
[11] A semiconductor device comprising the semiconductor film according to [10].
[12] The semiconductor device according to [11], which is a diode or a transistor.

  According to the film forming method of the present invention, a semiconductor film having excellent semiconductor characteristics can be formed.

It is a schematic block diagram of the film-forming apparatus (mist CVD) used in the Example. It is a figure which shows the result of the SIMS measurement in an Example. It is a schematic block diagram of the film-forming apparatus (mist CVD) used in the Example. It is a figure which shows the result of the SIMS measurement in an Example. It is a figure which shows the result of the SIMS measurement in an Example. It is a figure which shows the result of the SIMS measurement in an Example.

  In the film forming method of the present invention, a raw material solution containing metal and deuterium is atomized or dropletized (atomization / droplet forming step), and the obtained mist or droplet is placed in a film forming chamber with a carrier gas. It is characterized in that a semiconductor film is formed on the substrate by carrying out thermal reaction of the mist or droplets in the film forming chamber (conveying step) and then forming a semiconductor film on the substrate (depositing step).

(Atomization / droplet forming process)
In the atomization / droplet forming step, the raw material solution is atomized or dropletized. The atomizing means or droplet forming means of the raw material solution is not particularly limited as long as the raw material solution can be atomized or formed into droplets, and may be a known means. The atomizing means or droplet forming means used is preferred. Mist or droplets obtained using ultrasonic waves have a zero initial velocity and are preferable because they float in the air.For example, instead of spraying like a spray, they can be suspended in a space and transported as a gas. Since it is a possible mist, there is no damage due to collision energy, which is very suitable. The droplet size is not particularly limited and may be a droplet of about several mm, but is preferably 50 μm or less, and more preferably 1 to 10 μm.

(Raw material solution)
The raw material solution includes a material that can be atomized or formed into droplets, and is not particularly limited as long as it contains a metal and deuterium. Examples of the metal include one or more selected from gallium, iron, indium, aluminum, vanadium, titanium, chromium, rhodium, nickel, cobalt, zinc, magnesium, calcium, silicon, yttrium, strontium, and barium. In the present invention, the metal preferably contains at least one of aluminum, indium, and gallium, and more preferably contains at least gallium.

  In the present invention, as the raw material solution, a solution in which the metal is dissolved or dispersed in an organic solvent or water in the form of a complex or a salt can be suitably used. Examples of complex forms include acetylacetonate complexes, carbonyl complexes, ammine complexes, hydride complexes, and the like. Examples of the salt form include organic metal salts (for example, metal acetates, metal oxalates, metal citrates, etc.), sulfide metal salts, nitrate metal salts, phosphorylated metal salts, metal halide salts (for example, metal chlorides). Salt, metal bromide salt, metal iodide salt, etc.).

Moreover, you may mix additives, such as a hydrohalic acid and an oxidizing agent, with the said raw material solution. Examples of the hydrohalic acid include hydrobromic acid, hydrochloric acid, hydroiodic acid, etc. Among them, hydrobromic acid or hydroiodic acid is preferable. Examples of the oxidizing agent include hydrogen peroxide (H ₂ O ₂ ), sodium peroxide (Na ₂ O ₂ ), barium peroxide (BaO ₂ ), and benzoyl peroxide (C ₆ H ₅ CO) ₂ O _2. Peroxides, hypochlorous acid (HClO), perchloric acid, nitric acid, ozone water, organic peroxides such as peracetic acid and nitrobenzene.

The raw material solution may contain a dopant. Doping can be favorably performed by including a dopant in the raw material solution. The dopant is not particularly limited as long as the object of the present invention is not impaired. Examples of the dopant include n-type dopants such as tin, germanium, silicon, titanium, zirconium, vanadium or niobium, or p-type dopants. The concentration of the dopant may usually be about 1 × 10 ¹⁶ / cm ³ to 1 × 10 ²² / cm ³ , and the concentration of the dopant is set to a low concentration of about 1 × 10 ¹⁷ / cm ³ or less, for example. May be. Furthermore, according to the present invention, the dopant may be contained at a high concentration of about 1 × 10 ²⁰ / cm ³ or more.

  The solvent of the raw material solution is not particularly limited, and may be an inorganic solvent such as water, an organic solvent such as alcohol, or a mixed solvent of an inorganic solvent and an organic solvent. In the present invention, the solvent preferably contains water, more preferably water or a mixed solvent of water and alcohol.

  The deuterium may be contained in the raw material solution as an additive, or may be contained in the raw material solution by using a solute of the raw material solution or a hydrogen atom of the solvent substituted with deuterium. Good. As what substituted the hydrogen atom of the solvent with deuterium, heavy water etc. are mentioned, for example. When deuterium is included in the raw material solution as an additive, for example, deuterated hydrochloric acid, deuterated hydrobromic acid, deuterated hydroiodic acid, or the like may be used as the acid.

(Conveying process)
In the transfer step, the mist or the droplets are transferred into the film forming chamber with a carrier gas. The carrier gas is not particularly limited as long as the object of the present invention is not impaired. For example, oxygen, ozone, an inert gas such as nitrogen or argon, or a reducing gas such as hydrogen gas or forming gas is preferable. Can be mentioned. Further, the type of carrier gas may be one, but it may be two or more, and a diluent gas with a reduced flow rate (for example, 10-fold diluted gas) is further used as the second carrier gas. Also good. Further, the supply location of the carrier gas is not limited to one location but may be two or more locations. The flow rate of the carrier gas is not particularly limited, but is preferably 0.01 to 20 L / min, and more preferably 1 to 10 L / min. In the case of a dilution gas, the flow rate of the dilution gas is preferably 0.001 to 2 L / min, and more preferably 0.1 to 1 L / min.

(Film formation process)
In the film forming process, a semiconductor film is formed on the substrate by thermally reacting the mist or droplets in the film forming chamber. The thermal reaction may be performed as long as the mist or droplet reacts with heat, and the reaction conditions are not particularly limited as long as the object of the present invention is not impaired. In this step, the thermal reaction is usually performed at a temperature equal to or higher than the evaporation temperature of the solvent, but is preferably not too high (for example, 1000 ° C.) or less, more preferably 700 ° C. or less, and most preferably 350 ° C. to 700 ° C. preferable. In addition, the thermal reaction may be performed in any atmosphere of a vacuum, a non-oxygen atmosphere, a reducing gas atmosphere, and an oxygen atmosphere as long as the object of the present invention is not impaired. In an atmosphere of an inert gas such as nitrogen or argon or a reducing gas such as hydrogen gas or forming gas) or in an oxygen atmosphere. Moreover, although it may be performed under any conditions of atmospheric pressure, increased pressure, and reduced pressure, it is preferably performed under atmospheric pressure in the present invention. The film thickness can be set by adjusting the film formation time.

(Substrate)
The substrate is not particularly limited as long as it can support the semiconductor film. The material of the substrate is not particularly limited as long as the object of the present invention is not impaired, and may be a known substrate, an organic compound, or an inorganic compound. The shape of the substrate may be any shape and is effective for all shapes, for example, a plate shape such as a flat plate or a disk, a fiber shape, a rod shape, a columnar shape, a prismatic shape, A cylindrical shape, a spiral shape, a spherical shape, a ring shape and the like can be mentioned. In the present invention, a substrate is preferable. The thickness of the substrate is not particularly limited in the present invention.

  The substrate is not particularly limited as long as it is plate-shaped and serves as a support for the semiconductor film. An insulator substrate, a semiconductor substrate, a metal substrate or a conductive substrate may be used, but the substrate is preferably an insulator substrate, and a metal is formed on the surface. A substrate having a film is also preferable. Examples of the substrate include a base substrate containing a substrate material having a corundum structure as a main component, a base substrate containing a substrate material having a β-gallia structure as a main component, and a substrate material having a hexagonal crystal structure as a main component. Examples thereof include a base substrate. Here, the “main component” means that the substrate material having the specific crystal structure is preferably 50% or more, more preferably 70% or more, and still more preferably 90% by atomic ratio with respect to all components of the substrate material. % Or more, and may be 100%.

The substrate material is not particularly limited as long as the object of the present invention is not impaired, and may be a known material. As the substrate material having the corundum structure, for example, α-Al ₂ O ₃ (sapphire substrate) or α-Ga ₂ O ₃ is preferably exemplified, and an a-plane sapphire substrate, an m-plane sapphire substrate, and an r-plane sapphire substrate. A c-plane sapphire substrate, an α-type gallium oxide substrate (a-plane, m-plane or r-plane) and the like are more preferable examples. As a base substrate mainly composed of a substrate material having a β-gallia structure, for example, a β-Ga ₂ O ₃ substrate, or a Ga ₂ O ₃ and Al ₂ O ₃ containing Al ₂ O ₃ content of more than 0 wt% Examples thereof include a mixed crystal substrate of 60 wt% or less. In addition, examples of the base substrate whose main component is a substrate material having a hexagonal crystal structure include a SiC substrate, a ZnO substrate, and a GaN substrate.

In the present invention, the substrate preferably has a corundum structure, more preferably a base substrate composed mainly of a substrate material having a corundum structure, and most preferably a sapphire substrate or an α-type gallium oxide substrate. preferable. The substrate preferably contains aluminum, more preferably a base substrate mainly composed of an aluminum-containing substrate material having a corundum structure, and a sapphire substrate (preferably a c-plane sapphire substrate, an a-plane sapphire substrate, Most preferred are m-plane sapphire substrates and r-plane sapphire substrates. The base preferably contains an oxide, and examples of the oxide include a YSZ substrate, MgAl ₂ O ₄ substrate, ZnO substrate, MgO substrate, SrTiO ₃ substrate, Al ₂ O ₃ substrate, quartz substrate, Glass substrate, β-type gallium oxide substrate, barium titanate substrate, strontium titanate substrate, cobalt oxide substrate, copper oxide substrate, chromium oxide substrate, iron oxide substrate, Gd ₃ Ga ₅ O ₁₂ substrate, potassium tantalate substrate, aluminate acid Lanthanum substrate, lanthanum strontium aluminate substrate, lanthanum strontium gallate substrate, lithium niobate substrate, lithium tantalate substrate, lanthanum strontium aluminum tantalate, manganese oxide substrate, neodymium galide substrate, nickel oxide substrate, scandium magnesium aluminate substrate, acid Strontium, strontium titanate substrate, tin oxide substrate, tellurium oxide substrate, titanium oxide substrate, YAG substrate, yttrium aluminate substrate, lithium aluminate substrate, lithium gallate substrate, LAST substrate, neodymium gallate substrate, yttrium orthovana A date board etc. are mentioned.

(Annealing process)
In the present invention, it is preferable to perform an annealing treatment after the film forming step. By performing the annealing treatment, the hydrogen concentration of deuterium on the film surface can be further reduced. In addition, the concentration of light hydrogen can be further reduced as compared with the case where a film is formed using only light hydrogen. The annealing treatment temperature is not particularly limited as long as the object of the present invention is not impaired, and is usually 300 ° C. to 650 ° C., preferably 350 ° C. to 550 ° C. The annealing treatment time is usually 1 minute to 48 hours, preferably 10 minutes to 24 hours, and more preferably 30 minutes to 12 hours. The annealing treatment may be performed in any atmosphere as long as it does not hinder the object of the present invention, but preferably in a non-oxygen atmosphere (for example, an inert gas such as nitrogen or argon, hydrogen gas, or forming). An atmosphere of a reducing gas such as a gas), more preferably a nitrogen atmosphere.

  In the present invention, a crystalline semiconductor film may be provided directly on the substrate, or a crystalline semiconductor film may be provided via another layer such as a buffer layer (buffer layer) or a stress relaxation layer. Also good. The means for forming each layer is not particularly limited and may be a known means. In the present invention, the mist CVD method is preferred.

By manufacturing the semiconductor film as described above, deuterium can be included in part or all of the film surface. The deuterium concentration in part or all of the membrane surface is measured by secondary ion mass spectrometry (SIMS). The deuterium concentration means the concentration of deuterium in part or all of the film surface. In the present invention, the film surface on which the deuterium concentration is measured has a depth in the range of 100 nm to 300 nm from the outermost surface. The reason why the outermost surface is not included in the measurement region is that there are a sputtering unstable region and a sputtering stable region in SIMS measurement, and the sputtering unstable region depends on, for example, the primary ion species, energy, incident angle, and the like. This is because the element distribution tends to change, and therefore there is a problem that accurate analysis cannot be performed. In the present invention, the deuterium concentration, generally ranges from about ^{1 × 10 14 (atoms / cm} 3) or more, preferably at ^{1 × 10 16 (atoms / cm} 3) or more, 1 × ^{10 16} (Atoms / cm ³ ) to 1 × 10 ¹⁸ (atoms / cm ³ ) is more preferable, and 1 × 10 ¹⁶ (atoms / cm ³ ) to 1 × 10 ¹⁷ (atoms / cm ³ ) is the most preferable. preferable.
Further, by manufacturing the crystalline semiconductor film as described above, the concentration of light hydrogen in a part or all of the film surface is 2 × 10 ¹⁷ (atoms / cm ³ ) or less, preferably 1 × 10 ¹⁷ (atoms). / Cm ³ ) or less.

The semiconductor film has excellent semiconductor characteristics, particularly electrical characteristics, and is useful for semiconductor devices and the like. Further, the halogen concentration of a part or all of the surface of the semiconductor film is usually 5 × 10 ¹⁶ (atoms / cm ³ ) or less, preferably 1 × 10 ¹⁶ (atoms / cm ³ ) or less, more preferably It is reduced to 5 × 10 ¹⁵ (atoms / cm ³ ) or less, most preferably 3 × 10 ¹⁵ (atoms / cm ³ ) or less. In particular, even when a halogen compound is used as a raw material, halogen impurities Therefore, better semiconductor characteristics can be exhibited. Examples of the halogen to be reduced include chlorine and bromine. In the present invention, the halogen to be reduced is preferably chlorine or bromine, and more preferably chlorine and bromine.

In general, the semiconductor film preferably contains a semiconductor having a corundum structure as a main component. The semiconductor may be an oxide semiconductor, a nitride semiconductor, a carbide semiconductor, or a silicon-containing semiconductor. In the present invention, the semiconductor is an oxide semiconductor. Preferably there is. The semiconductor preferably contains at least one of aluminum, indium, and gallium, and more preferably contains at least gallium. Examples of suitable semiconductors include InAlGaO-based semiconductors, and more specifically, for example, In _X Al _Y Ga _Z O ₃ (0 ≦ X ≦ 2, 0 ≦ Y ≦ 2, 0 ≦ Z ≦ 2, X + Y + Z = 1.5 to 2.5) and the like. In the present invention, the InAlGaO-based semiconductor preferably contains gallium. Here, the "main component", for example the case where the semiconductor is a α-Ga ₂ O _3, the atomic ratio of gallium in a metal element in the film include α-Ga ₂ O ₃ at a ratio of more than 0.5 If so, that's fine. In the present invention, the atomic ratio of gallium in the metal element in the film is preferably 0.7 or more, and more preferably 0.8 or more. The thickness of the semiconductor film is not particularly limited, and may be 1 μm or less, or 1 μm or more. The semiconductor film is usually single crystal, but may be polycrystalline.

  The semiconductor film preferably contains a dopant. The dopant is not particularly limited and may be a known one. Examples of the dopant include n-type dopants such as tin, germanium, silicon, titanium, zirconium, vanadium or niobium, or p-type dopants. In the present invention, the dopant is preferably Sn or Ge, and more preferably Ge. The dopant content is preferably 0.00001 atomic% or more, more preferably 0.00001 atomic% to 20 atomic%, and more preferably 0.00001 atomic% to 10 atomic% in the composition of the semiconductor film. Most preferably.

  In the present invention, the semiconductor film may be used for a semiconductor device or the like after using a known means such as peeling from the substrate or the like, or may be used as it is for a semiconductor device or the like as a laminated structure. .

  Examples of the semiconductor device include a semiconductor laser, a diode, or a transistor. More specifically, for example, a transistor or TFT such as MIS or HEMT, a Schottky barrier diode using a semiconductor-metal junction, or other P Examples thereof include a PN or PIN diode combined with a layer, a light emitting / receiving element, and the like. In the present invention, the semiconductor device is preferably a diode or a transistor.

  In the present invention, the semiconductor device is preferably a semiconductor device including at least the semiconductor film and an electrode. For example, when the semiconductor device is a Schottky barrier diode, the electrode may be a Schottky electrode or an ohmic electrode. For example, when the semiconductor device is a MOSFET, a gate electrode, a source It may be an electrode or a drain electrode. Examples of the electrode material include Al, Mo, Co, Zr, Sn, Nb, Fe, Cr, Ta, Ti, Au, Pt, V, Mn, Ni, Cu, Hf, W, Ir, Zn, In, Metals such as Pd, Nd or Ag, or alloys thereof, tin oxide, zinc oxide, indium oxide, indium tin oxide (ITO), metal oxide conductive films such as indium zinc oxide (IZO), polyaniline, polythiophene or polypyrrole Organic conductive compounds such as or a mixture thereof. The electrode can be formed by a known means such as a vacuum deposition method, a sputtering method, a CVD method, or the like.

  Since the semiconductor device has a semiconductor film containing deuterium, it has excellent semiconductor characteristics, particularly electrical characteristics. For example, the mobility of the semiconductor film is significantly improved as compared with a semiconductor film having a corundum structure formed by mist CVD without using deuterium.

  Examples of the present invention will be described below, but the present invention is not limited thereto.

Example 1
1. Film Forming Apparatus A mist CVD apparatus 1 used in this example will be described with reference to FIG. The mist CVD apparatus 1 includes a carrier gas source 2a for supplying a carrier gas, a flow rate adjusting valve 3a for adjusting the flow rate of the carrier gas delivered from the carrier gas source 2a, and a carrier gas for supplying a carrier gas (dilution). A dilution source 2b, a flow rate adjusting valve 3b for adjusting the flow rate of the carrier gas (dilution) sent from the carrier gas (dilution) source 2b, a mist generating source 4 in which the raw material solution 4a is accommodated, and water 5a. A container 5 to be placed, an ultrasonic vibrator 6 attached to the bottom surface of the container 5, a film forming chamber 7, a supply pipe 9 connecting the mist generating source 4 to the film forming chamber 7, and the film forming chamber 7. An installed hot plate 8 and an exhaust port 11 for discharging mist, droplets and exhaust gas after thermal reaction are provided. A substrate 10 is installed on the hot plate 8.

2. Preparation of raw material solution Mixing gallium bromide and tin bromide in heavy water and adjusting the aqueous solution so that the atomic ratio of tin to gallium is 1: 0.08. 10% was contained, and this was used as a raw material solution.

3. Preparation of film formation The raw material solution 4a obtained in the above was accommodated in the mist generating source 4. Next, a sapphire substrate was placed on the hot plate 8 as the substrate 10, and the hot plate 8 was operated to raise the temperature in the film forming chamber 7 to 600 ° C. Next, the flow rate control valves 3a and 3b are opened, the carrier gas is supplied from the carrier gas supply means 2a and 2b, which are carrier gas sources, into the film forming chamber 7, and the atmosphere in the film forming chamber 7 is sufficiently filled with the carrier gas. After the replacement, the carrier gas flow rate was adjusted to 5.0 L / min, and the carrier gas (dilution) flow rate was adjusted to 0.5 L / min. Note that oxygen was used as a carrier gas.

4). Formation of Semiconductor Film Next, the ultrasonic vibrator 6 was vibrated at 2.4 MHz, and the vibration was propagated to the raw material solution 4a through the water 5a, whereby the raw material solution 4a was atomized to generate the mist 4b. . The mist 4b is introduced into the film forming chamber 7 by the carrier gas through the supply pipe 9, and the mist thermally reacts in the film forming chamber 7 at 600 ° C. under atmospheric pressure. A film was formed on top. The film thickness was 3.2 μm and the film formation time was 240 minutes.

5). Evaluation Using the XRD diffractometer, the above 4. Was subjected to phase identification of the film obtained by, the obtained film is α-Ga ₂ 0 _3, the resistivity was 8Emuomegacm. Moreover, about the obtained film | membrane, the deuterium concentration in a film | membrane was measured using the secondary ion mass spectrometer. The results of SIMS are shown in FIG. As apparent from FIG. 2, the deuterium concentration was 1 × 10 ¹⁶ (atoms / cm ³ ) to 1 × 10 ¹⁸ (atoms / cm ³ ). When the concentration of light hydrogen was measured in the same manner, the concentration of light hydrogen was 2 × 10 ¹⁷ (atoms / cm ³ ) or less. Further, when the Hall effect measurement was performed on the obtained film, the mobility was 13.81 cm ² / Vs at a carrier density of 7.80 × 10 ¹⁸ cm ⁻³ . This is a difference in effect of about 5 times or more compared with the case where the film is formed without using deuterium, and it can be seen that the electrical characteristics of the semiconductor film of the present invention are excellent.

(Example 2)
The film obtained in Example 1 was annealed at 500 ° C. for 1 hour in a nitrogen atmosphere. The film obtained by the annealing treatment was used as the film of Example 2, and evaluated in the same manner as in Example 1. When the phase of the obtained film was identified, the obtained film was α-Ga ₂ O ₃ and the resistivity was 10 mΩcm. Moreover, about the obtained film | membrane, the deuterium concentration in a film | membrane was measured using the secondary ion mass spectrometer. The results of SIMS are shown in FIG. As apparent from FIG. 2, the deuterium concentration was 1 × 10 ¹⁶ (atoms / cm ³ ) to 1 × 10 ¹⁸ (atoms / cm ³ ). When the concentration of light hydrogen was measured in the same manner, the concentration of light hydrogen was 1 × 10 ¹⁷ (atoms / cm ³ ) or less.

(Example 3)
1. Film Forming Apparatus The mist CVD apparatus 19 used in Example 3 will be described with reference to FIG. The mist CVD apparatus 19 includes a susceptor 21 on which the substrate 20 is placed, a carrier gas supply means 22a for supplying a carrier gas, and a flow rate adjusting valve 23a for adjusting the flow rate of the carrier gas sent from the carrier gas supply means 22a. The carrier gas (dilution) supply means 22b for supplying the carrier gas (dilution), the flow rate adjusting valve 23b for adjusting the flow rate of the carrier gas sent from the carrier gas (dilution) supply means 22b, and the raw material solution 24a are accommodated. Mist generating source 24, a container 25 in which water 25a is placed, an ultrasonic vibrator 26 attached to the bottom surface of the container 25, a supply pipe 27 made of a quartz tube having an inner diameter of 40 mm, and a peripheral portion of the supply pipe 27 And a heater 28 installed in the vehicle. The susceptor 21 is made of quartz, and the surface on which the substrate 20 is placed is inclined from the horizontal plane. Both the supply pipe 27 and the susceptor 21 serving as a film formation chamber are made of quartz, so that impurities derived from the apparatus are prevented from being mixed into the film formed on the substrate 20.

2. Preparation of raw material solution Mixing gallium bromide and tin bromide in heavy water and adjusting the aqueous solution so that the atomic ratio of tin to gallium is 1: 0.08. 10% was contained, and this was used as a raw material solution.

3. Preparation of film formation The raw material solution 24a obtained in the above was accommodated in the mist generating source 24. Next, a sapphire substrate was placed on the susceptor 21 as the substrate 20, and the heater 28 was operated to raise the temperature in the film forming chamber 27 to 550 ° C. Next, the flow rate control valves 23a and 23b are opened, and carrier gas is supplied from the carrier gas supply means 22a and 22b, which are carrier gas sources, into the film forming chamber 27. After the replacement, the carrier gas flow rate was adjusted to 5 L / min, and the carrier gas (dilution) flow rate was adjusted to 0.5 L / min. Note that oxygen was used as a carrier gas.

4). Formation of Semiconductor Film Next, the ultrasonic vibrator 26 was vibrated at 2.4 MHz, and the vibration was propagated to the raw material solution 24a through the water 25a, whereby the raw material solution 24a was atomized to generate mist. The mist was introduced into the film forming chamber 27 by the carrier gas, and the mist reacted in the film forming chamber 27 at 550 ° C. under atmospheric pressure, so that a semiconductor film was formed on the substrate 20. The film thickness was 3.6 μm and the film formation time was 170 minutes.

5). Evaluation Using the XRD diffractometer, the above 4. Was subjected to phase identification of the film obtained by, the obtained film is α-Ga ₂ 0 _3, the resistivity was 10Emuomegacm. Moreover, about the obtained film | membrane, the deuterium concentration in a film | membrane was measured using the secondary ion mass spectrometer. The results of SIMS are shown in FIG. As is clear from FIG. 4, the deuterium concentration in the film was 1 × 10 ¹⁶ (atoms / cm ³ ) to 1 × 10 ¹⁷ (atoms / cm ³ ). When the concentration of light hydrogen was measured in the same manner, the concentration of light hydrogen was 2 × 10 ¹⁷ (atoms / cm ³ ) or less. Similarly to the case where the deuterium concentration was measured, the concentration of halogen (bromine, chlorine) in the film was also measured using a secondary ion mass spectrometer. The measurement result of bromine concentration is shown in FIG. 5, and the measurement result of chlorine concentration is shown in FIG. As apparent from FIGS. 5 and 6, the bromine concentration in the film is 3 × 10 ¹⁵ (atoms / cm ³ ) or less, the chlorine concentration is 2 × 10 ¹⁵ (atoms / cm ³ ) or less, and halogen It can be seen that the concentration of is low.

Example 4
The film obtained in Example 3 was annealed in a nitrogen atmosphere at 400 ° C. for 10 hours. The film obtained by the annealing treatment was used as the film of Example 4, and was evaluated in the same manner as in Example 3. When the phase of the obtained film was identified, the obtained film was α-Ga ₂ O ₃ . Moreover, about the obtained film | membrane, the deuterium concentration in a film | membrane was measured using the secondary ion mass spectrometer. The results of SIMS are shown in FIG. As is clear from FIG. 4, the deuterium concentration in the film was 1 × 10 ¹⁶ (atoms / cm ³ ) to 1 × 10 ¹⁷ (atoms / cm ³ ). The concentration of light hydrogen was 2 × 10 ¹⁷ (atoms / cm ³ ) or less. Moreover, about the obtained film | membrane, the density | concentration of the halogen (chlorine, bromine) in a film | membrane was measured using the secondary ion mass spectrometer. The measurement result of bromine concentration is shown in FIG. 5, and the measurement result of chlorine concentration is shown in FIG. As is apparent from FIGS. 5 and 6, the chlorine concentration is 2 × 10 ¹⁵ (atoms / cm ³ ) or less, the bromine concentration is 2 × 10 ¹⁵ (atoms / cm ³ ) or less, and the halogen impurity is 2 It can be seen that it is as low as × 10 ¹⁵ (atoms / cm ³ ) or less.

  The semiconductor film obtained by the film forming method of the present invention is excellent in semiconductor characteristics, and thus is useful for a semiconductor device.

DESCRIPTION OF SYMBOLS 1 Mist CVD apparatus 2a Carrier gas source 2b Carrier gas (dilution) source 3a Flow control valve 3b Flow control valve 4 Mist generation source 4a Raw material solution 4b Mist 5 Container 5a Water 6 Ultrasonic vibrator 7 Deposition chamber 8 Hot plate 9 Supply Tube 10 Substrate 11 Exhaust port 19 Mist CVD apparatus 20 Substrate 21 Susceptor 22a Carrier gas supply means 22b Carrier gas (dilution) supply means 23a Flow control valve 23b Flow control valve 24 Mist generation source 24a Raw material solution 25 Container 25a Water 26 Ultrasonic vibration Child 27 Supply pipe 28 Heater 29 Exhaust port

Claims (12)

  A raw material solution containing metal is atomized or formed into droplets, and the obtained mist or droplets are conveyed to a substrate installed in a film forming chamber with a carrier gas, and then the mist or droplets are thermally reacted to form the substrate. A method for forming a semiconductor film on the substrate, wherein the raw material solution contains deuterium.   The film forming method according to claim 1, wherein the solvent of the raw material solution is heavy water.   The film forming method according to claim 1, wherein an acid in which hydrogen atoms are substituted with deuterium is added to the raw material solution to atomize or form droplets.   The film forming method according to claim 1, wherein the raw material solution contains a dopant.   The film forming method according to claim 1, wherein the metal includes at least one of aluminum, indium, and gallium.   The film forming method according to claim 1, wherein the thermal reaction is performed at a temperature of 350 ° C. to 700 ° C.   The film forming method according to claim 1, wherein the substrate has a corundum structure.   The film-forming method in any one of Claims 1-7 in which a base | substrate contains aluminum.   The film forming method according to claim 1, wherein the substrate contains an oxide.   A semiconductor film formed by the film forming method according to claim 1.   A semiconductor device comprising the semiconductor film according to claim 10. The semiconductor device according to claim 11, wherein the semiconductor device is a diode or a transistor.