WO2022059669A1 - β-GA2O3-BASED SINGLE CRYSTAL FILM AND METHOD OF MANUFACTURING SAME - Google Patents

β-GA2O3-BASED SINGLE CRYSTAL FILM AND METHOD OF MANUFACTURING SAME Download PDF

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WO2022059669A1
WO2022059669A1 PCT/JP2021/033709 JP2021033709W WO2022059669A1 WO 2022059669 A1 WO2022059669 A1 WO 2022059669A1 JP 2021033709 W JP2021033709 W JP 2021033709W WO 2022059669 A1 WO2022059669 A1 WO 2022059669A1
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single crystal
crystal film
gas
suboxide
system single
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French (fr)
Japanese (ja)
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クァン トゥ ティユ
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株式会社ノベルクリスタルテクノロジー
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    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
    • C23C16/22—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the deposition of inorganic material, other than metallic material
    • C23C16/30—Deposition of compounds, mixtures or solid solutions, e.g. borides, carbides, nitrides
    • C23C16/40—Oxides
    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B25/00—Single-crystal growth by chemical reaction of reactive gases, e.g. chemical vapour-deposition growth
    • C30B25/02—Epitaxial-layer growth
    • C30B25/18—Epitaxial-layer growth characterised by the substrate
    • C30B25/20—Epitaxial-layer growth characterised by the substrate the substrate being of the same materials as the epitaxial layer
    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
    • C30B29/10—Inorganic compounds or compositions
    • C30B29/16—Oxides
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/02104—Forming layers
    • H01L21/02107—Forming insulating materials on a substrate
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer
    • H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic System or AIIIBV compounds with or without impurities, e.g. doping materials
    • H01L21/20—Deposition of semiconductor materials on a substrate, e.g. epitaxial growth solid phase epitaxy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L29/00—Semiconductor devices adapted for rectifying, amplifying, oscillating or switching, or capacitors or resistors with at least one potential-jump barrier or surface barrier, e.g. PN junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof  ; Multistep manufacturing processes therefor
    • H01L29/40—Electrodes ; Multistep manufacturing processes therefor
    • H01L29/43—Electrodes ; Multistep manufacturing processes therefor characterised by the materials of which they are formed
    • H01L29/47—Schottky barrier electrodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L29/00—Semiconductor devices adapted for rectifying, amplifying, oscillating or switching, or capacitors or resistors with at least one potential-jump barrier or surface barrier, e.g. PN junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof  ; Multistep manufacturing processes therefor
    • H01L29/66—Types of semiconductor device ; Multistep manufacturing processes therefor
    • H01L29/86—Types of semiconductor device ; Multistep manufacturing processes therefor controllable only by variation of the electric current supplied, or only the electric potential applied, to one or more of the electrodes carrying the current to be rectified, amplified, oscillated or switched
    • H01L29/861—Diodes
    • H01L29/872—Schottky diodes

Definitions

  • the present invention relates to a ⁇ -Ga 2 O 3 system single crystal film ( ⁇ -Ga 2 O 3 -based single crystal film) and a method for producing the same.
  • HVPE method hydride vapor phase growth method
  • TSVPE method trihalide vapor phase growth method
  • MBE method molecular beam epitaxy method
  • the Ga halide compound GaCl, GaCl 3
  • Cl derived from the raw material is used as an impurity in the ⁇ -Ga 2 O 3 system. It mixes in the single crystal film. Since Cl acts as a shallow donor in the ⁇ -Ga 2 O 3 system semiconductor, carriers are formed even when an undoped (unintentionally undoped) ⁇ -Ga 2 O 3 system single crystal film is formed. (Free electrons) will be generated.
  • the concentration of Cl mixed in the ⁇ -Ga 2 O3 system single crystal film is about 1 to 2 ⁇ 10 16 / cm 3 , and the carriers (free electrons) generated are.
  • the concentration is about the same.
  • the withstand voltage of the device is inversely proportional to the carrier concentration of the Ga 2 O 3 system single crystal film. Therefore, in order to obtain a ⁇ -Ga 2 O 3 system single crystal film capable of manufacturing a device having a higher withstand voltage, an impurity ⁇ -Ga 2 O 3 system single crystal film such as Cl, which acts as a dopant, is used. It is important to prevent unintended contamination.
  • an object of the present invention is a method for producing a ⁇ - Ga 2 O3 system single crystal film capable of suppressing unintentional mixing of impurities having a high crystal growth rate and acting as a dopant, and ⁇ produced by the method. -To provide a Ga 2 O 3 system single crystal film.
  • one aspect of the present invention is the method for producing a ⁇ - Ga 2 O3 system single crystal film according to the following [1] to [4], ⁇ -Ga 2 according to [5] and [6].
  • An O3 series single crystal film is provided.
  • ⁇ -Ga 2 O 3 single crystal which is a single crystal of ⁇ -Ga 2 O 3 , or a single crystal of ⁇ -Ga 2 O 3 in which a part of Ga is substituted with one or both of Al and In.
  • a method for producing a ⁇ -Ga 2 O 3 system single crystal film composed of crystals which does not involve the production of a substance containing an impurity that acts as a dopant in the ⁇ - Ga 2 O 3 system single crystal film.
  • 3 is Ga, Al, or In
  • a method for producing a ⁇ - Ga 2 O3 system single crystal film which comprises a step of making the single crystal film.
  • the suboxide gas of Ga 2 O 3 is produced by reacting Ga 2 O 3 with the metal Ga, and in the case of producing the suboxide gas of Al 2 O 3 , Al ⁇ -Ga according to the above [1], which is produced by reacting 2 O 3 with metal Al to generate In 2 O 3 suboxide gas by reacting In 2 O 3 with metal In.
  • a method for producing a 2O3 series single crystal film [ 3 ] The ⁇ -Ga 2 O3 system single crystal film according to the above [1] or [2], which produces the suboxide gas at an atmospheric temperature of 800 ° C.
  • the ⁇ -Ga 2 O 3 system single crystal film is epitaxially grown under an atmospheric temperature of 800 ° C. or higher.
  • ⁇ -Ga 2 O 3 single crystal which is a single crystal of ⁇ -Ga 2 O 3 , or a single crystal of ⁇ -Ga 2 O 3 in which a part of Ga is substituted with one or both of Al and In.
  • the Sn content is 1 ⁇ 10 15 / cm 3 or less
  • the Si content is 5 ⁇ 10 15 / cm 3 or less
  • the F content is 1 ⁇ 10 14 / cm 3 or less.
  • a method for producing a ⁇ - Ga 2 O3 system single crystal film capable of suppressing unintentional mixing of impurities acting as a dopant and having a high crystal growth rate, and ⁇ -Ga produced by the method can be provided.
  • FIG. 1 is a vertical sectional view of a crystal laminated structure according to an embodiment of the present invention.
  • FIG. 2 is a vertical sectional view of a vapor phase growth apparatus according to an embodiment of the present invention.
  • FIG. 3 is a graph showing the relationship between the partial pressure and the temperature of the Ga 2 O gas and the Ga O gas in the Ga 2 O 3 suboxide gas.
  • FIG. 4 is a graph showing the equilibrium constants in the formation reaction of Ga 2 O 3 by each film forming method of the method according to the embodiment of the present invention, the HVPE method, and the THVPE method.
  • FIG. 5 is a graph showing the measurement results of elemental analysis by SIMS of the crystal laminated structure according to the embodiment of the present invention.
  • FIG. 6 is an observation image of the surface morphology of a ⁇ -Ga 2 O 3 single crystal film having a thickness of 3 ⁇ m with an optical microscope.
  • FIG. 1 is a vertical cross-sectional view of the crystal laminated structure 1 according to the embodiment of the present invention.
  • the crystal laminated structure 1 is a ⁇ -Ga 2 O 3 system single crystal film formed by epitaxial crystal growth on the main surface 11 of the ⁇ -Ga 2 O 3 system substrate 10 and the ⁇ -Ga 2 O 3 system substrate 10. Has twelve.
  • the ⁇ -Ga 2 O 3 system substrate 10 is a substrate made of a ⁇ -Ga 2 O 3 system single crystal.
  • the ⁇ -Ga 2 O 3 system single crystal is a single crystal of ⁇ -Ga 2 O 3 which is Ga 2 O 3 having a ⁇ -type crystal structure, or a part of Ga is one of Al and In. It is a single crystal of ⁇ -Ga 2 O 3 substituted with or both, and (Ga x Aly In (1-xy) ) 2 O 3 (0 ⁇ x ⁇ 1, 0 ⁇ y ⁇ 1, 0 ⁇ It has an ideal composition represented by x + y ⁇ 1).
  • (Ga x Al 1-x ) 2 O 3 (0 ⁇ x ⁇ 1) in which some Ga is replaced with Al has a larger bandgap than Ga 2 O 3 , and some Ga is In.
  • the substituted (Ga x In 1-x ) 2 O 3 (0 ⁇ x ⁇ 1) has a smaller bandgap than the Ga 2 O 3 .
  • the ⁇ - Ga 2 O3 system substrate 10 may contain a dopant such as Sn or Si.
  • the plane orientation of the main surface 11 of the ⁇ - Ga 2 O3 system substrate 10 is not particularly limited, and is, for example, (001), (010), (-201), or (101).
  • the ⁇ -Ga 2 O 3 system substrate 10 is obtained by slicing a bulk crystal of a Ga 2 O 3 system single crystal grown by a melt growth method such as an FZ (Floating Zone) method or an EFG (Edge Defined Film Fed Growth) method. It is formed by polishing the surface.
  • a melt growth method such as an FZ (Floating Zone) method or an EFG (Edge Defined Film Fed Growth) method. It is formed by polishing the surface.
  • a sapphire substrate or a silicon substrate may be used instead of the ⁇ - Ga 2 O3 system substrate 10.
  • the ⁇ -Ga 2 O 3 system single crystal film 12 is made of a ⁇ -Ga 2 O 3 system single crystal, similarly to the ⁇ -Ga 2 O 3 system substrate 10.
  • the ⁇ -Ga 2 O 3 system single crystal film 12 is formed by an oxidation reaction of a suboxide of A 2 O 3 (A is Ga, Al, or In), and ⁇ -Ga 2 O is formed in the formation of the sub oxide. Since substances containing impurities such as Cl and C that act as dopants are not generated in the three -system single crystal film 12, the concentration of impurities that function as dopants is very low. Therefore, the ⁇ - Ga 2 O3 system single crystal film 12 has a very low carrier concentration and is excellent as a material for a device having a high withstand voltage.
  • the concentration of Cl in the ⁇ -Ga 2 O3 system single crystal film 12 is 5 ⁇ 10 14 / cm 3 or less
  • the content of C is 2 ⁇ 10 16 / cm 3 or less
  • the content of Sn is 1 ⁇ 10 15
  • the content of Si is 5 ⁇ 10 15 / cm 3 or less
  • the content of F is 1 ⁇ 10 14 / cm 3 or less
  • the content of H is 2 ⁇ 10 17 / cm 3 or less.
  • Cl, C, Si, F, and H are all impurities that act as donors in the ⁇ - Ga 2 O3 system single crystal film 12.
  • the HVPE method and the THVPE method use a halide compound of Ga (GaCl, GaCl 3 ) as a raw material, it is very difficult to suppress the concentration of Cl to 1 ⁇ 10 16 / cm 3 or less. Further, in the organometallic chemical vapor deposition method (MOCVD method), since an organometallic raw material (trimethylgallium (TMGa), triethylgallium (TEGa)) is used as a raw material, the concentration of C is reduced to 3 ⁇ 10 16 / cm 3 or less. It is very difficult to suppress.
  • TMGa trimethylgallium
  • TMGa triethylgallium
  • the suboxide of Ga 2 O 3 is Ga 2 O or Ga O having an oxidation number of Ga lower than that of Ga 2 O 3 .
  • the suboxide of Al 2 O 3 is Al 2 O or Al O having an oxidation number of Al lower than that of Al 2 O 3
  • the suboxide of In 2 O 3 has an oxidation number of In higher than that of In 2 O 3 . Also low In 2 O or In O.
  • a Ga 2 O 3 suboxide is used as a raw material.
  • the Ga 2 O 3 suboxide and Al 2 O 3 suboxide is used as a raw material.
  • the suboxide and In of Ga 2 O 3 2 O 3 suboxide is used as a raw material.
  • ⁇ -Ga 2 O 3 system single crystal film 12 as ⁇ - (Ga x Al y In (1-xy) ) 2 O 3 (0 ⁇ x ⁇ 1, 0 ⁇ y ⁇ 1, 0 ⁇ x + y ⁇ 1)
  • a Ga 2 O 3 suboxide, an Al 2 O 3 suboxide, and an In 2 O 3 suboxide are used as raw materials.
  • the ⁇ - Ga 2 O3 system single crystal film 12 may contain a dopant intentionally added such as Si and Sn.
  • a dopant intentionally added such as Si and Sn.
  • FIG. 2 is a vertical cross-sectional view of the vapor phase growth apparatus 2 according to the embodiment of the present invention.
  • the gas phase growth device 2 is installed in a reaction chamber 20 having a first gas introduction port 21, a second gas introduction port 22, a third gas introduction port 23, and an exhaust port 25, and around the reaction chamber 20.
  • a first heating means 27 and a second heating means 28 for heating a predetermined area in the reaction chamber 20 are provided.
  • a reaction vessel 26 containing a raw material for a Ga 2 O 3 suboxide gas (hereinafter referred to as Ga 2 O 3 suboxide gas) is arranged, and a Ga 2 O 3 suboxide gas is generated. It has a raw material reaction region R1 and a crystal growth region R2 in which the ⁇ -Ga 2 O 3 system substrate 10 is arranged and the ⁇ -Ga 2 O 3 system single crystal film 12 is grown.
  • the reaction chamber 20 is made of, for example, quartz glass.
  • the reaction vessel 26 is made of, for example, quartz glass, and the raw materials for the Ga 2 O 3 suboxide gas contained in the reaction vessel 26 are solid (for example, single crystal bulk or polycrystalline powder) Ga 2 O 3 and liquid. Metal Ga.
  • the solid Ga 2 O 3 and the liquid metal Ga are housed in the reaction vessel 26 in contact with each other.
  • Ga 2 O 3 may be a single mass or a powder.
  • the Ga 2 O 3 sub Gas phase growth apparatus 2 When forming a ⁇ - (Ga x Al 1-x ) 2 O 3 (0 ⁇ x ⁇ 1) single crystal film as the ⁇ -Ga 2 O 3 system single crystal film 12, the Ga 2 O 3 sub Gas phase growth apparatus 2 provided with a raw material reaction region R1 for producing an Al 2 O 3 suboxide gas (hereinafter referred to as Al 2 O 3 suboxide gas ) in addition to the raw material reaction region R1 for producing an oxide gas. Is used.
  • a reaction vessel 26 containing Al 2 O 3 which is a raw material of the Al 2 O 3 suboxide gas and the metal Al is arranged.
  • a vapor phase growth apparatus 2 provided with a raw material reaction region R1 for producing an In 2 O 3 suboxide gas (hereinafter referred to as In 2 O 3 suboxide gas ) in addition to the raw material reaction region R1 for producing an oxide gas. Is used.
  • a reaction vessel 26 containing In 2 O 3 which is a raw material of the In 2 O 3 suboxide gas and the metal In is arranged.
  • the first heating means 27 and the second heating means 28 can heat the raw material reaction region R1 and the crystal growth region R2 of the reaction chamber 20, respectively.
  • the first heating means 27 and the second heating means 28 are, for example, resistance heating type or radiant heating type heating devices.
  • the first gas introduction port 21 is a port for introducing a carrier gas for carrying the generated suboxide gas into the raw material reaction region R1 of the reaction chamber 20.
  • the second gas introduction port 22 is a port for introducing O 2 gas, which is a raw material gas for oxygen, into the crystal growth region R2 together with the carrier gas.
  • the third gas introduction port 23 is a port for introducing a carrier gas and, if necessary, a raw material gas of a dopant intentionally added such as SiC4 into the crystal growth region R2 of the reaction chamber 20.
  • the carrier gas introduced from the first gas introduction port 21, the second gas introduction port 22, and the third gas introduction port 23 is an inert gas such as N2 gas or Ar gas. If N is mixed in the ⁇ -Ga 2 O 3 system single crystal film 12, it may act as an acceptor, but by adjusting the conditions such as the partial pressure of the raw material supply and the temperature, the ⁇ -Ga 2 O 3 system single crystal film It is possible to prevent contamination with 12. On the other hand, since Ar does not act as a dopant even if it is mixed in the ⁇ - Ga 2 O3 system single crystal film 12, it is preferable to use Ar gas as a carrier gas.
  • the raw material reaction region R1 of the reaction chamber 20 is heated by using the first heating means 27, and the atmospheric temperature of the raw material reaction region R1 is kept at a predetermined temperature, for example, 800 ° C. or higher.
  • a predetermined temperature for example, 800 ° C. or higher.
  • the supply partial pressure of the Ga 2 O 3 suboxide gas can be made to be about the same as the supply partial pressure of the Ga raw material gas of the HVPE method.
  • the growth rate of the ⁇ -Ga 2 O 3 system single crystal film 12 is proportional to the supply partial pressure of this Ga 2 O 3 suboxide gas.
  • the atmospheric temperature of the raw material reaction region R1 is set lower than the softening point of the reaction chamber 20 and the reaction vessel 26 (for example, about 1200 ° C. if made of quartz glass).
  • Ga 2 O 3 in the reaction vessel 26 is reacted with the metal Ga under the above-mentioned atmospheric temperature to generate Ga 2 O 3 suboxide gas.
  • Ga 2 O gas and Ga O gas, which are Ga 2 O 3 suboxide gases, are produced by the chemical reactions represented by the following formulas 1 and 2, respectively.
  • raw materials containing elements such as Cl and C that act as dopants in the ⁇ -Ga 2 O 3 system single crystal film 12 are used to generate the Ga 2 O 3 suboxide gas. I can't. Therefore, with the generation of Ga 2 O gas, a substance containing an element acting as a dopant is not generated in the ⁇ -Ga 2 O 3 system single crystal film 12.
  • Ga 2 O 3 and metal Ga are solid and liquid, respectively, because of their low vapor pressure, but Ga 2 O and Ga O produced by these reactions have higher vapor pressure than Ga 2 O 3 and metal Ga. It becomes a gas. Due to the difference in vapor pressure from this raw material, high-purity Ga 2 O gas and Ga O gas, that is, Ga 2 O 3 suboxide gas can be obtained.
  • FIG. 3 is a graph showing the relationship between the partial pressure and temperature of Ga 2 O gas and Ga O gas in the suboxide gas generated by heating the contacted Ga 2 O 3 and the metal Ga.
  • the concentration of GaO gas in the Ga2O3 suboxide gas is negligibly low compared to the concentration of Ga2O gas. That is, the Ga 2 O 3 suboxide gas is substantially composed of Ga 2 O gas.
  • the partial pressure of Ga 2 O gas and Ga O gas is determined almost exclusively by the atmospheric temperature of the raw material reaction region R1 if the mixture (contact) of Ga 2 O 3 and the metal Ga is sufficient. Therefore, the amount of Ga 2 O 3 suboxide gas supplied to the crystal growth region R2 is determined by the atmospheric temperature of the raw material reaction region R1 and the flow rate of the carrier gas carrying the Ga 2 O 3 suboxide gas.
  • the generated Ga 2 O suboxide gas is carried to the crystal growth region R2 by a carrier gas such as Ar gas introduced from the first gas introduction port 21.
  • the generated Al 2 O suboxide gas and In 2 O suboxide gas also have a crystal growth region due to a carrier gas such as Ar gas introduced from the first gas introduction port 21. It is carried to R2.
  • the Ga 2 O suboxide gas generated in the raw material reaction region R1 is introduced from the second gas introduction port 22.
  • the O 2 gas was mixed, and the ⁇ -Ga 2 O 3 system substrate 10 was exposed to the mixed gas, and the ⁇ -Ga 2 O 3 system single crystal was placed on the main surface 11 of the ⁇ -Ga 2 O 3 system substrate 10.
  • the film 12 is epitaxially grown.
  • Ga 2 O 3 constituting the ⁇ -Ga 2 O 3 system single crystal film 12 is produced by a chemical reaction represented by the following formulas 7 and 8.
  • the growth temperature of the ⁇ - Ga 2 O3 system single crystal film 12 is preferably 800 ° C. or higher. If the temperature is lower than 800 ° C., a metastable phase of ⁇ -Ga 2 O 3 or ⁇ -Ga 2 O 3 may be generated and a single crystal may not be obtained.
  • the growth pressure of the ⁇ - Ga 2 O3 system single crystal film 12 is, for example, about 1 atm.
  • the growth temperature of the ⁇ -Ga 2 O 3 system single crystal film 12 is the melting point of Ga 2 O 3 (about 1900 ° C.) and the softening point of the reaction chamber 20 (for example, about 1200 ° C. if made of quartz glass). It is set lower than the lower one.
  • FIG. 4 is a graph showing the equilibrium constants in the formation reaction of Ga 2 O 3 by each film forming method of the method according to the embodiment of the present invention, the HVPE method, and the THVPE method.
  • the upper horizontal axis of FIG. 4 is temperature (° C.)
  • the lower horizontal axis is 1000 / T (K -1 ) (T is absolute temperature)
  • the vertical axis is logK (K is the equilibrium constant).
  • FIG. 4 shows that the method according to the embodiment of the present invention is more likely to generate Ga 2 O 3 than the HVPE method and the THVPE method.
  • the growth rate of the ⁇ - Ga 2 O3 system single crystal film 12 is about 1 to 10 ⁇ m / h depending on the growth conditions such as the growth temperature. This growth rate is higher than the growth rate of other crystal growth methods, and is significantly higher than, for example, the growth rate of about several hundred nm / h in the MBE method. Further, from the demonstration experiment, it has been confirmed that there is a sufficient possibility that the growth rate of the HVPE method (several tens of ⁇ m / h) or higher can be achieved by further adjusting the growth conditions.
  • Equation 10 shows the main chemical reactions that produce (Ga x In 1-x ) 2 O 3 .
  • a means such as polishing is used to reduce the electrical resistance of the ⁇ -Ga 2 O 3 system substrate 10 in the thickness direction.
  • the ⁇ -Ga 2 O 3 system substrate 10 may be thinned by using it. Further, the ⁇ -Ga 2 O 3 system single crystal film 12 obtained through the above steps may be separated from the ⁇ -Ga 2 O 3 system substrate 10 by means such as polishing.
  • Ga 2 O 3 suboxide gas, Al 2 O 3 suboxide gas, In 2 O 3 suboxide gas which are raw materials for the ⁇ -Ga 2 O 3 system single crystal film 12, and the like.
  • the O 2 gas and the inert gas which is a carrier gas, do not contain impurities such as Cl and C that function as dopants in the ⁇ -Ga 2 O 3 system single crystal film 12, and are the raw materials for the suboxide gas.
  • Ga 2 O 3 , Al 2 O 3 , In 2 O 3 , metal Ga, metal Al, and metal In also contain impurities such as Cl and C that function as dopants in the ⁇ -Ga 2 O 3 system single crystal film 12.
  • a substance containing an impurity that functions as a dopant is not generated in the ⁇ - Ga 2 O3 system single crystal film 12 with the generation of the suboxide gas. Therefore, the concentration of impurities that function as dopants in the ⁇ -Ga 2 O 3 system single crystal film 12 is extremely low, and ⁇ -Ga 2 O 3 system singles are used as materials for devices that require high withstand voltage, such as Schottky barrier diodes. By using the crystal film 12, a very high withstand voltage can be obtained.
  • the method for producing the ⁇ -Ga 2 O 3 system single crystal film 12 according to the embodiment of the present invention is also excellent in the growth rate of the ⁇ -Ga 2 O 3 system single crystal film 12, and therefore, the device to be applied. Even if the ⁇ -Ga 2 O 3 system single crystal film 12 is required to have a certain thickness due to its characteristics, the ⁇ -Ga 2 O 3 system single crystal film 12 is formed in a realistic time at the production site. be able to.
  • FIG. 5 is a graph showing the measurement results of elemental analysis of the crystal laminated structure 1 by the secondary ion mass spectrometry (SIMS).
  • SIMS secondary ion mass spectrometry
  • a ⁇ -Ga 2 O 3 single crystal substrate was used as the ⁇ -Ga 2 O 3 system substrate 10
  • a ⁇ -Ga 2 O 3 single crystal film was used as the ⁇ -Ga 2 O 3 system single crystal film 12.
  • FIG. 5 shows the concentrations of the impurity elements Cl, Sn, and Si that act as dopants in the ⁇ - Ga 2 O3 system single crystal film 12.
  • the horizontal axis of FIG. 5 is the depth ( ⁇ m) from the surface of the ⁇ -Ga 2 O 3 single crystal film (the surface of the crystal laminated structure 1), and the vertical axis is the concentration of each element (/ cm 3 ). ..
  • the dotted line on the right side of the graph represents the background (BG) level of each element concentration.
  • the background level is the concentration of each element measured with nothing contained in the analyzer.
  • the range in the depth direction indicated by " ⁇ -Ga 2 O 3 single crystal film” and “substrate” on the upper side of the graph includes ⁇ - Ga 2 O 3 single crystal film and Sn as dopants , respectively.
  • the measurement area of the system substrate 10 is shown.
  • the rise in the concentration of each element near the surface of the ⁇ -Ga 2 O 3 single crystal film is due to the influence of the surface adsorbent, and does not indicate the concentration of each element inside.
  • the concentration of Cl in the ⁇ -Ga 2 O 3 single crystal film is consistent with the background concentration of 5 ⁇ 10 14 / cm 3 , which is below the detection limit of the SIMS apparatus, that is, 5 It can be seen that it is ⁇ 10 14 / cm 3 or less.
  • the concentration of C in the ⁇ -Ga 2 O 3 single crystal film is consistent with the background concentration of 2 ⁇ 10 16 / cm 3 , which is below the detection limit of the SIMS device, that is, 2 ⁇ 10 16 /. It can be seen that it is cm 3 or less.
  • the concentration of Sn in the ⁇ -Ga 2 O 3 single crystal film is consistent with the background concentration of 1 ⁇ 10 15 / cm 3 , which is below the detection limit of the SIMS device, that is, 1 ⁇ 10 15 /. It can be seen that it is cm 3 or less.
  • the concentration of Si in the ⁇ -Ga 2 O 3 single crystal film is consistent with the background concentration of 5 ⁇ 10 15 / cm 3 , which is below the detection limit of the SIMS device, that is, 5 ⁇ 10 15 /. It can be seen that it is cm 3 or less.
  • the concentration of F in the ⁇ -Ga 2 O 3 single crystal film is consistent with the background concentration of 1 ⁇ 10 14 / cm 3 , which is below the detection limit of the SIMS device, that is, 1 ⁇ 10 14 /. It can be seen that it is cm 3 or less.
  • These very low concentrations of Cl, C, Sn, Si, and F are Ga 2 O 3 suboxide gas and O 2 gas, Ga 2 O 3 suboxide gas, which are the raw materials for the ⁇ -Ga 2 O 3 single crystal film. This is because Ga 2 O 3 and metal Ga, which are the raw materials of the above, and the inert gas, which is the carrier gas, do not contain Cl, C, Sn, Si, and F.
  • the reaction chamber 20 and the reaction vessel 26 of the vapor phase growth apparatus 2 used for forming the ⁇ -Ga 2 O 3 single crystal film are made of quartz glass (SiO 2 ) and contain Si, but the above-mentioned ⁇ - From the concentration of Si in the Ga 2 O 3 system single crystal film 12, it is considered that Si contained in the reaction chamber 20 and the reaction vessel 26 was hardly mixed in the ⁇ -Ga 2 O 3 single crystal film.
  • the ⁇ -Ga 2 O 3 system substrate 10 which is the base for the epitaxial crystal growth of the ⁇ -Ga 2 O 3 single crystal film, contained Sn having a concentration of about 5 ⁇ 10 18 / cm 3 as a dopant. From the concentration of Sn in the ⁇ -Ga 2 O 3 single crystal film, it is considered that Sn contained in the ⁇ -Ga 2 O 3 system substrate 10 was hardly mixed in the ⁇ -Ga 2 O 3 single crystal film.
  • the concentration of H in the ⁇ -Ga 2 O 3 single crystal film is not performed because the background level of the SIMS device is as high as 2 ⁇ 10 17 / cm 3 and meaningful data cannot be obtained.
  • Ga 2 O 3 suboxide gas and O 2 gas which are the raw materials for the ⁇ -Ga 2 O 3 single crystal film
  • Ga 2 O 3 and metal Ga which are the raw materials for the Ga 2 O 3 suboxide gas
  • a carrier gas Since H is not contained in a certain inert gas, it is presumed that the concentration of H in the ⁇ -Ga 2 O 3 single crystal film is significantly lower than the background level of 2 ⁇ 10 17 / cm 3 .
  • FIG. 6 is an observation image of the surface morphology of a ⁇ -Ga 2 O 3 single crystal film having a thickness of 3 ⁇ m with an optical microscope. According to the observation image of FIG. 6, streaks peculiar to the surface of the epitaxially grown crystal can be confirmed. From this surface condition, it can be seen that a film having a quality comparable to that formed by the HVPE method is obtained.
  • the evaluation results of the ⁇ -Ga 2 O 3 single crystal film as the ⁇ -Ga 2 O 3 system single crystal film 12 are shown, but other ⁇ -Ga 2 O 3 system single crystal films are shown. Even when ⁇ - (Ga x Al 1-x ) 2 O 3 single crystal film or ⁇ - (Ga x In 1-x ) 2 O 3 single crystal film is evaluated, ⁇ -Ga 2 O 3 Similar to the single crystal film, the unintentional mixing of impurities acting as dopants is suppressed, so that the same evaluation results can be obtained.
  • a method for producing a ⁇ -Ga 2 O 3 series single crystal film that has a high crystal growth rate and can suppress unintentional mixing of impurities that act as dopants, and a ⁇ -Ga 2 O 3 series single crystal produced by that method. Provides a membrane.

Abstract

Provided is a method of manufacturing a β-Ga2O3-based single crystal film 12 that comprises β-Ga2O3-based single crystal including single crystal of β-Ga2O3 or single crystal of β-Ga2O3 wherein Ga is partially substituted by Al and/or In. This method of manufacturing the β-Ga2O3-based single crystal film 12 comprises a step for generating a suboxide gas of A2O3 (wherein A stands for Ga, Al or In) without the generation of a substance containing impurities that act as dopants in the β-Ga2O3-based single crystal film 12, and a step for reacting the suboxide gas with O2 gas and thus epitaxially growing the β-Ga2O3-based single crystal film 12 on a β-Ga2O3-based substrate 10.<sb /> <sb /> <sb /> <sb />

Description

β－Ｇａ２Ｏ３系単結晶膜及びその製造方法β-Ga2O3 series single crystal film and its manufacturing method
　本発明は、β－Ｇａ２Ｏ３系単結晶膜（β－Ｇａ２Ｏ３－ｂａｓｅｄ　ｓｉｎｇｌｅ　ｃｒｙｓｔａｌ　ｆｉｌｍ）及びその製造方法に関する。 The present invention relates to a β-Ga 2 O 3 system single crystal film (β-Ga 2 O 3 -based single crystal film) and a method for producing the same.
　従来、ハイドライド気相成長法（ＨＶＰＥ法）やトリハライド気相成長法（ＴＨＶＰＥ法）によりβ－Ｇａ２Ｏ３系単結晶膜を成長させる技術が知られている（例えば、特許文献１参照）。特にＨＶＰＥ法は、分子線エピタキシー法（ＭＢＥ法）などの他の成長方法と比較して結晶成長速度が大きく、生産現場において現実的な時間で厚い結晶膜を形成することができるという優れた特徴を有する。 Conventionally, a technique for growing a β - Ga 2 O3 system single crystal film by a hydride vapor phase growth method (HVPE method) or a trihalide vapor phase growth method (THVPE method) is known (see, for example, Patent Document 1). In particular, the HVPE method has an excellent feature that the crystal growth rate is higher than that of other growth methods such as the molecular beam epitaxy method (MBE method), and a thick crystal film can be formed in a realistic time at a production site. Has.
特許第６３７６６００号公報Japanese Patent No. 6376600
　しかしながら、ＨＶＰＥ法及びＴＨＶＰＥ法では、Ｇａのハライド化合物（ＧａＣｌ、ＧａＣｌ３）をβ－Ｇａ２Ｏ３系単結晶膜の原料として用いるため、原料由来のＣｌが不純物としてβ－Ｇａ２Ｏ３系単結晶膜に混入してしまう。Ｃｌはβ－Ｇａ２Ｏ３系半導体中で浅いドナーとして働くため、たとえアンドープ（意図的なドーピングをしていない）のβ－Ｇａ２Ｏ３系単結晶膜を形成した場合であってもキャリア（自由電子）が発生してしまう。例えば、ＧａＣｌを原料として用いた場合には、β－Ｇａ２Ｏ３系単結晶膜に混入するＣｌの濃度は１～２×１０１６／ｃｍ３程度であり、発生するキャリア（自由電子）の濃度も同程度である。 However, in the HVPE method and the THVPE method, since the Ga halide compound (GaCl, GaCl 3 ) is used as a raw material for the β-Ga 2 O 3 system single crystal film, Cl derived from the raw material is used as an impurity in the β-Ga 2 O 3 system. It mixes in the single crystal film. Since Cl acts as a shallow donor in the β-Ga 2 O 3 system semiconductor, carriers are formed even when an undoped (unintentionally undoped) β-Ga 2 O 3 system single crystal film is formed. (Free electrons) will be generated. For example, when GaCl is used as a raw material, the concentration of Cl mixed in the β-Ga 2 O3 system single crystal film is about 1 to 2 × 10 16 / cm 3 , and the carriers (free electrons) generated are. The concentration is about the same.
　例えば、β－Ｇａ２Ｏ３系単結晶膜をパワーデバイスに用いる場合、デバイスの耐圧はＧａ２Ｏ３系単結晶膜のキャリア濃度と反比例する関係にある。このため、より高耐圧のデバイスを製造することができるβ－Ｇａ２Ｏ３系単結晶膜を得るためには、Ｃｌのようなドーパントとして働く不純物のβ－Ｇａ２Ｏ３系単結晶膜への意図しない混入を抑えることが重要である。 For example, when a β-Ga 2 O 3 system single crystal film is used as a power device, the withstand voltage of the device is inversely proportional to the carrier concentration of the Ga 2 O 3 system single crystal film. Therefore, in order to obtain a β-Ga 2 O 3 system single crystal film capable of manufacturing a device having a higher withstand voltage, an impurity β-Ga 2 O 3 system single crystal film such as Cl, which acts as a dopant, is used. It is important to prevent unintended contamination.
　したがって、本発明の目的は、結晶成長速度が大きく、かつドーパントとして働く不純物の意図しない混入を抑えることのできるβ－Ｇａ２Ｏ３系単結晶膜の製造方法、及びその方法により製造されたβ－Ｇａ２Ｏ３系単結晶膜を提供することにある。 Therefore, an object of the present invention is a method for producing a β - Ga 2 O3 system single crystal film capable of suppressing unintentional mixing of impurities having a high crystal growth rate and acting as a dopant, and β produced by the method. -To provide a Ga 2 O 3 system single crystal film.
　本発明の一態様は、上記目的を達成するために、下記［１］～［４］のβ－Ｇａ２Ｏ３系単結晶膜の製造方法、［５］、［６］のβ－Ｇａ２Ｏ３系単結晶膜を提供する。 In order to achieve the above object, one aspect of the present invention is the method for producing a β - Ga 2 O3 system single crystal film according to the following [1] to [4], β-Ga 2 according to [5] and [6]. An O3 series single crystal film is provided.
［１］β－Ｇａ２Ｏ３の単結晶、又は、一部のＧａがＡｌ、Ｉｎの一方又は両方で置換されたβ－Ｇａ２Ｏ３の単結晶であるβ－Ｇａ２Ｏ３系単結晶からなるβ－Ｇａ２Ｏ３系単結晶膜の製造方法であって、前記β－Ｇａ２Ｏ３系単結晶膜の中でドーパントとして働く不純物を含む物質の生成を伴わずにＡ２Ｏ３（ＡはＧａ、Ａｌ、又はＩｎ）のサブオキサイドガスを生成する工程と、前記サブオキサイドガスをＯ２ガスと反応させて、基板上に前記β－Ｇａ２Ｏ３系単結晶膜をエピタキシャル成長させる工程と、を含む、β－Ｇａ２Ｏ３系単結晶膜の製造方法。
［２］前記サブオキサイドガスを生成する工程において、Ｇａ２Ｏ３のサブオキサイドガスをＧａ２Ｏ３と金属Ｇａを反応させて生成し、Ａｌ２Ｏ３のサブオキサイドガスを生成する場合はＡｌ２Ｏ３と金属Ａｌを反応させて生成し、Ｉｎ２Ｏ３のサブオキサイドガスを生成する場合はＩｎ２Ｏ３と金属Ｉｎを反応させて生成する、前記［１］に記載のβ－Ｇａ２Ｏ３系単結晶膜の製造方法。
［３］前記サブオキサイドガスを生成する工程において、８００℃以上の雰囲気温度下で前記サブオキサイドガスを生成する、前記［１］又は［２］に記載のβ－Ｇａ２Ｏ３系単結晶膜の製造方法。
［４］前記β－Ｇａ２Ｏ３系単結晶膜をエピタキシャル成長させる工程において、８００℃以上の雰囲気温度下で前記β－Ｇａ２Ｏ３系単結晶膜をエピタキシャル成長させる、前記［１］～［３］のいずれか１項に記載のβ－Ｇａ２Ｏ３系単結晶膜の製造方法。
［５］β－Ｇａ２Ｏ３の単結晶、又は、一部のＧａがＡｌ、Ｉｎの一方又は両方で置換されたβ－Ｇａ２Ｏ３の単結晶であるβ－Ｇａ２Ｏ３系単結晶からなり、Ｃｌの濃度が５×１０１４／ｃｍ３以下、Ｃの含有量が２×１０１６／ｃｍ３以下である、β－Ｇａ２Ｏ３系単結晶膜。
［６］Ｓｎの含有量が１×１０１５／ｃｍ３以下、Ｓｉの含有量が５×１０１５／ｃｍ３以下、Ｆの含有量が１×１０１４／ｃｍ３以下である、前記［５］に記載のβ－Ｇａ２Ｏ３系単結晶膜。 [1] β-Ga 2 O 3 single crystal, which is a single crystal of β-Ga 2 O 3 , or a single crystal of β-Ga 2 O 3 in which a part of Ga is substituted with one or both of Al and In. A method for producing a β-Ga 2 O 3 system single crystal film composed of crystals, which does not involve the production of a substance containing an impurity that acts as a dopant in the β - Ga 2 O 3 system single crystal film. 3 (A is Ga, Al, or In) The step of generating a suboxide gas and the suboxide gas being reacted with the O 2 gas to epitaxially grow the β-Ga 2 O 3 system single crystal film on the substrate. A method for producing a β - Ga 2 O3 system single crystal film, which comprises a step of making the single crystal film.
[2] In the step of producing the suboxide gas, the suboxide gas of Ga 2 O 3 is produced by reacting Ga 2 O 3 with the metal Ga, and in the case of producing the suboxide gas of Al 2 O 3 , Al Β-Ga according to the above [1], which is produced by reacting 2 O 3 with metal Al to generate In 2 O 3 suboxide gas by reacting In 2 O 3 with metal In. A method for producing a 2O3 series single crystal film.
[ 3 ] The β-Ga 2 O3 system single crystal film according to the above [1] or [2], which produces the suboxide gas at an atmospheric temperature of 800 ° C. or higher in the step of producing the suboxide gas. Manufacturing method.
[4] In the step of epitaxially growing the β-Ga 2 O 3 system single crystal film, the β-Ga 2 O 3 system single crystal film is epitaxially grown under an atmospheric temperature of 800 ° C. or higher. ] The method for producing a β - Ga 2 O3 system single crystal film according to any one of the above items.
[5] β-Ga 2 O 3 single crystal, which is a single crystal of β-Ga 2 O 3 , or a single crystal of β-Ga 2 O 3 in which a part of Ga is substituted with one or both of Al and In. A β-Ga 2 O 3 series single crystal film composed of crystals, having a Cl concentration of 5 × 10 14 / cm 3 or less and a C content of 2 × 10 16 / cm 3 or less.
[6] The Sn content is 1 × 10 15 / cm 3 or less, the Si content is 5 × 10 15 / cm 3 or less, and the F content is 1 × 10 14 / cm 3 or less. ] The β - Ga 2 O3 system single crystal film according to.
　本発明によれば、結晶成長速度が大きく、かつドーパントとして働く不純物の意図しない混入を抑えることのできるβ－Ｇａ２Ｏ３系単結晶膜の製造方法、及びその方法により製造されたβ－Ｇａ２Ｏ３系単結晶膜を提供することができる。 According to the present invention, a method for producing a β - Ga 2 O3 system single crystal film capable of suppressing unintentional mixing of impurities acting as a dopant and having a high crystal growth rate, and β-Ga produced by the method. A 2O3 system single crystal film can be provided.
図１は、本発明の実施の形態に係る結晶積層構造体の垂直断面図である。FIG. 1 is a vertical sectional view of a crystal laminated structure according to an embodiment of the present invention. 図２は、本発明の実施の形態に係る気相成長装置の垂直断面図である。FIG. 2 is a vertical sectional view of a vapor phase growth apparatus according to an embodiment of the present invention. 図３は、Ｇａ２Ｏ３サブオキサイドガス中のＧａ２ＯガスとＧａＯガスの分圧と温度の関係を示すグラフである。FIG. 3 is a graph showing the relationship between the partial pressure and the temperature of the Ga 2 O gas and the Ga O gas in the Ga 2 O 3 suboxide gas. 図４は、本発明の実施の形態に係る方法、ＨＶＰＥ法、及びＴＨＶＰＥ法の各成膜法によるＧａ２Ｏ３の生成反応における平衡定数を示すグラフである。FIG. 4 is a graph showing the equilibrium constants in the formation reaction of Ga 2 O 3 by each film forming method of the method according to the embodiment of the present invention, the HVPE method, and the THVPE method. 図５は、本発明の実施例に係る結晶積層構造体のＳＩＭＳによる元素分析の測定結果を示すグラフである。FIG. 5 is a graph showing the measurement results of elemental analysis by SIMS of the crystal laminated structure according to the embodiment of the present invention. 図６は、厚さ３μｍのβ－Ｇａ２Ｏ３単結晶膜の表面モフォロジーの光学顕微鏡による観察像である。FIG. 6 is an observation image of the surface morphology of a β-Ga 2 O 3 single crystal film having a thickness of 3 μm with an optical microscope.
〔実施の形態〕
（結晶積層構造体の構成）
　図１は、本発明の実施の形態に係る結晶積層構造体１の垂直断面図である。結晶積層構造体１は、β－Ｇａ２Ｏ３系基板１０と、β－Ｇａ２Ｏ３系基板１０の主面１１上にエピタキシャル結晶成長により形成されたβ－Ｇａ２Ｏ３系単結晶膜１２を有する。 [Embodiment]
(Structure of crystal laminated structure)
FIG. 1 is a vertical cross-sectional view of the crystal laminated structure 1 according to the embodiment of the present invention. The crystal laminated structure 1 is a β-Ga 2 O 3 system single crystal film formed by epitaxial crystal growth on the main surface 11 of the β-Ga 2 O 3 system substrate 10 and the β-Ga 2 O 3 system substrate 10. Has twelve.
　β－Ｇａ２Ｏ３系基板１０は、β－Ｇａ２Ｏ３系単結晶からなる基板である。ここで、β－Ｇａ２Ｏ３系単結晶とは、β型の結晶構造を有するＧａ２Ｏ３であるβ－Ｇａ２Ｏ３の単結晶、又は、一部のＧａがＡｌ、Ｉｎの一方又は両方で置換されたβ－Ｇａ２Ｏ３の単結晶であり、（ＧａｘＡｌｙＩｎ（１－ｘ－ｙ））２Ｏ３（０＜ｘ≦１、０≦ｙ≦１、０＜ｘ＋ｙ≦１）で表される理想組成を有する。例えば、一部のＧａがＡｌで置換された（ＧａｘＡｌ１－ｘ）２Ｏ３（０＜ｘ＜１）は、Ｇａ２Ｏ３よりもバンドギャップが大きく、一部のＧａがＩｎで置換された（ＧａｘＩｎ１－ｘ）２Ｏ３（０＜ｘ＜１）は、Ｇａ２Ｏ３よりもバンドギャップが小さい。また、β－Ｇａ２Ｏ３系基板１０は、Ｓｎ、Ｓｉなどのドーパントを含んでもよい。 The β-Ga 2 O 3 system substrate 10 is a substrate made of a β-Ga 2 O 3 system single crystal. Here, the β-Ga 2 O 3 system single crystal is a single crystal of β-Ga 2 O 3 which is Ga 2 O 3 having a β-type crystal structure, or a part of Ga is one of Al and In. It is a single crystal of β-Ga 2 O 3 substituted with or both, and (Ga x Aly In (1-xy) ) 2 O 3 (0 <x ≦ 1, 0 ≦ y ≦ 1, 0 < It has an ideal composition represented by x + y ≦ 1). For example, (Ga x Al 1-x ) 2 O 3 (0 <x <1) in which some Ga is replaced with Al has a larger bandgap than Ga 2 O 3 , and some Ga is In. The substituted (Ga x In 1-x ) 2 O 3 (0 <x <1) has a smaller bandgap than the Ga 2 O 3 . Further, the β - Ga 2 O3 system substrate 10 may contain a dopant such as Sn or Si.
　β－Ｇａ２Ｏ３系基板１０の主面１１の面方位は特に限定されず、例えば、（００１）、（０１０）、（－２０１）、又は（１０１）である。 The plane orientation of the main surface 11 of the β - Ga 2 O3 system substrate 10 is not particularly limited, and is, for example, (001), (010), (-201), or (101).
　β－Ｇａ２Ｏ３系基板１０は、例えば、ＦＺ（Floating Zone）法やＥＦＧ（Edge Defined Film Fed Growth）法等の融液成長法により育成したＧａ２Ｏ３系単結晶のバルク結晶をスライスし、表面を研磨することにより形成される。 The β-Ga 2 O 3 system substrate 10 is obtained by slicing a bulk crystal of a Ga 2 O 3 system single crystal grown by a melt growth method such as an FZ (Floating Zone) method or an EFG (Edge Defined Film Fed Growth) method. It is formed by polishing the surface.
　なお、β－Ｇａ２Ｏ３系基板１０の代わりにサファイア基板やシリコン基板を用いてもよい。 A sapphire substrate or a silicon substrate may be used instead of the β - Ga 2 O3 system substrate 10.
　β－Ｇａ２Ｏ３系単結晶膜１２は、β－Ｇａ２Ｏ３系基板１０と同様に、β－Ｇａ２Ｏ３系単結晶からなる。β－Ｇａ２Ｏ３系単結晶膜１２は、Ａ２Ｏ３（ＡはＧａ、Ａｌ、又はＩｎ）のサブオキサイドの酸化反応により形成され、また、そのサブオキサイドの生成においてβ－Ｇａ２Ｏ３系単結晶膜１２の中でドーパントとして働くＣｌ、Ｃなどの不純物を含む物質が生成されないため、ドーパントとして機能する不純物の濃度が非常に低い。このため、β－Ｇａ２Ｏ３系単結晶膜１２はキャリア濃度が非常に低く、高耐圧のデバイスの材料として優れている。 The β-Ga 2 O 3 system single crystal film 12 is made of a β-Ga 2 O 3 system single crystal, similarly to the β-Ga 2 O 3 system substrate 10. The β-Ga 2 O 3 system single crystal film 12 is formed by an oxidation reaction of a suboxide of A 2 O 3 (A is Ga, Al, or In), and β-Ga 2 O is formed in the formation of the sub oxide. Since substances containing impurities such as Cl and C that act as dopants are not generated in the three -system single crystal film 12, the concentration of impurities that function as dopants is very low. Therefore, the β - Ga 2 O3 system single crystal film 12 has a very low carrier concentration and is excellent as a material for a device having a high withstand voltage.
　例えば、β－Ｇａ２Ｏ３系単結晶膜１２のＣｌの濃度は５×１０１４／ｃｍ３以下、Ｃの含有量は２×１０１６／ｃｍ３以下、Ｓｎの含有量は１×１０１５／ｃｍ３以下、Ｓｉの含有量は５×１０１５／ｃｍ３以下、Ｆの含有量は１×１０１４／ｃｍ３以下、Ｈの含有量は２×１０１７／ｃｍ３以下である。Ｃｌ、Ｃ、Ｓｉ、Ｆ、Ｈは、いずれもβ－Ｇａ２Ｏ３系単結晶膜１２の中でドナーとして働く不純物である。 For example, the concentration of Cl in the β-Ga 2 O3 system single crystal film 12 is 5 × 10 14 / cm 3 or less, the content of C is 2 × 10 16 / cm 3 or less, and the content of Sn is 1 × 10 15 The content of Si is 5 × 10 15 / cm 3 or less, the content of F is 1 × 10 14 / cm 3 or less, and the content of H is 2 × 10 17 / cm 3 or less. Cl, C, Si, F, and H are all impurities that act as donors in the β - Ga 2 O3 system single crystal film 12.
　なお、ＨＶＰＥ法及びＴＨＶＰＥ法では、Ｇａのハライド化合物（ＧａＣｌ、ＧａＣｌ３）を原料として用いるため、Ｃｌの濃度を１×１０１６／ｃｍ３以下に抑えることは非常に困難である。また、有機金属化学気相成長法（ＭＯＣＶＤ法）では、有機金属原料（トリメチルガリウム（ＴＭＧａ）、トリエチルガリウム（ＴＥＧａ））を原料として用いるため、Ｃの濃度を３×１０１６／ｃｍ３以下に抑えることは非常に困難である。 Since the HVPE method and the THVPE method use a halide compound of Ga (GaCl, GaCl 3 ) as a raw material, it is very difficult to suppress the concentration of Cl to 1 × 10 16 / cm 3 or less. Further, in the organometallic chemical vapor deposition method (MOCVD method), since an organometallic raw material (trimethylgallium (TMGa), triethylgallium (TEGa)) is used as a raw material, the concentration of C is reduced to 3 × 10 16 / cm 3 or less. It is very difficult to suppress.
　ここで、Ｇａ２Ｏ３のサブオキサイドは、Ｇａの酸化数がＧａ２Ｏ３よりも低いＧａ２Ｏ又はＧａＯである。また、Ａｌ２Ｏ３のサブオキサイドは、Ａｌの酸化数がＡｌ２Ｏ３よりも低いＡｌ２Ｏ又はＡｌＯであり、Ｉｎ２Ｏ３のサブオキサイドは、Ｉｎの酸化数がＩｎ２Ｏ３よりも低いＩｎ２Ｏ又はＩｎＯである。β－Ｇａ２Ｏ３系単結晶膜１２としてβ－Ｇａ２Ｏ３単結晶膜を形成する場合は、Ｇａ２Ｏ３のサブオキサイドを原料に用いる。β－Ｇａ２Ｏ３系単結晶膜１２としてβ－（ＧａｘＡｌ１－ｘ）２Ｏ３（０＜ｘ＜１）単結晶膜を形成する場合は、Ｇａ２Ｏ３のサブオキサイドとＡｌ２Ｏ３のサブオキサイドを原料に用いる。β－Ｇａ２Ｏ３系単結晶膜１２としてβ－（ＧａｘＩｎ１－ｘ）２Ｏ３（０＜ｘ＜１）単結晶膜を形成する場合は、Ｇａ２Ｏ３のサブオキサイドとＩｎ２Ｏ３のサブオキサイドを原料に用いる。β－Ｇａ２Ｏ３系単結晶膜１２としてβ－（ＧａｘＡｌｙＩｎ（１－ｘ－ｙ））２Ｏ３（０＜ｘ≦１、０≦ｙ≦１、０＜ｘ＋ｙ≦１）単結晶膜を形成する場合は、Ｇａ２Ｏ３のサブオキサイド、Ａｌ２Ｏ３のサブオキサイド、及びＩｎ２Ｏ３のサブオキサイドを原料に用いる。 Here, the suboxide of Ga 2 O 3 is Ga 2 O or Ga O having an oxidation number of Ga lower than that of Ga 2 O 3 . Further, the suboxide of Al 2 O 3 is Al 2 O or Al O having an oxidation number of Al lower than that of Al 2 O 3 , and the suboxide of In 2 O 3 has an oxidation number of In higher than that of In 2 O 3 . Also low In 2 O or In O. When forming a β-Ga 2 O 3 single crystal film as the β-Ga 2 O 3 system single crystal film 12, a Ga 2 O 3 suboxide is used as a raw material. When forming a β- (Ga x Al 1-x ) 2 O 3 (0 <x <1) single crystal film as the β-Ga 2 O 3 system single crystal film 12, the Ga 2 O 3 suboxide and Al 2 O 3 suboxide is used as a raw material. When forming a β- (Ga x In 1-x ) 2 O 3 (0 <x <1) single crystal film as the β-Ga 2 O 3 system single crystal film 12, the suboxide and In of Ga 2 O 3 2 O 3 suboxide is used as a raw material. β-Ga 2 O 3 system single crystal film 12 as β- (Ga x Al y In (1-xy) ) 2 O 3 (0 <x ≦ 1, 0 ≦ y ≦ 1, 0 <x + y ≦ 1) When forming a single crystal film, a Ga 2 O 3 suboxide, an Al 2 O 3 suboxide, and an In 2 O 3 suboxide are used as raw materials.
　なお、β－Ｇａ２Ｏ３系基板１０からの不純物拡散を防ぐため、β－Ｇａ２Ｏ３系基板１０とβ－Ｇａ２Ｏ３系単結晶膜１２の間にバッファ層が形成されてもよい。 Even if a buffer layer is formed between the β-Ga 2 O 3 system substrate 10 and the β-Ga 2 O 3 system single crystal film 12 in order to prevent the diffusion of impurities from the β-Ga 2 O 3 system substrate 10. good.
　また、β－Ｇａ２Ｏ３系単結晶膜１２は、Ｓｉ、Ｓｎなどの意図的に添加されたドーパントを含んでもよい。この場合、上述のようにβ－Ｇａ２Ｏ３系単結晶膜１２への意図しないドーパントの添加が抑えられるため、意図的に添加するドーパントの濃度を高い精度で制御することができる。 Further, the β - Ga 2 O3 system single crystal film 12 may contain a dopant intentionally added such as Si and Sn. In this case, since the unintended addition of the dopant to the β - Ga 2 O3 system single crystal film 12 is suppressed as described above, the concentration of the intentionally added dopant can be controlled with high accuracy.
（気相成長装置の構造）
　以下に、本実施の形態に係るβ－Ｇａ２Ｏ３系単結晶膜１２としてのβ－Ｇａ２Ｏ３単結晶膜の成長に用いる気相成長装置の構造の一例について説明する。 (Structure of vapor phase growth device)
Hereinafter, an example of the structure of the vapor phase growth apparatus used for the growth of the β-Ga 2 O 3 single crystal film as the β-Ga 2 O 3 system single crystal film 12 according to the present embodiment will be described.
　図２は、本発明の実施の形態に係る気相成長装置２の垂直断面図である。気相成長装置２は、第１のガス導入ポート２１、第２のガス導入ポート２２、第３のガス導入ポート２３、及び排気ポート２５を有する反応チャンバー２０と、反応チャンバー２０の周囲に設置され、反応チャンバー２０内の所定の領域を加熱する第１の加熱手段２７及び第２の加熱手段２８を備える。 FIG. 2 is a vertical cross-sectional view of the vapor phase growth apparatus 2 according to the embodiment of the present invention. The gas phase growth device 2 is installed in a reaction chamber 20 having a first gas introduction port 21, a second gas introduction port 22, a third gas introduction port 23, and an exhaust port 25, and around the reaction chamber 20. , A first heating means 27 and a second heating means 28 for heating a predetermined area in the reaction chamber 20 are provided.
　反応チャンバー２０は、Ｇａ２Ｏ３のサブオキサイドのガス（以下、Ｇａ２Ｏ３サブオキサイドガスと呼ぶ）の原料が収容された反応容器２６が配置され、Ｇａ２Ｏ３サブオキサイドガスが生成される原料反応領域Ｒ１と、β－Ｇａ２Ｏ３系基板１０が配置され、β－Ｇａ２Ｏ３系単結晶膜１２の成長が行われる結晶成長領域Ｒ２を有する。反応チャンバー２０は、例えば、石英ガラスからなる。 In the reaction chamber 20, a reaction vessel 26 containing a raw material for a Ga 2 O 3 suboxide gas (hereinafter referred to as Ga 2 O 3 suboxide gas) is arranged, and a Ga 2 O 3 suboxide gas is generated. It has a raw material reaction region R1 and a crystal growth region R2 in which the β-Ga 2 O 3 system substrate 10 is arranged and the β-Ga 2 O 3 system single crystal film 12 is grown. The reaction chamber 20 is made of, for example, quartz glass.
　反応容器２６は、例えば、石英ガラスからなり、反応容器２６に収容されるＧａ２Ｏ３サブオキサイドガスの原料は固体（例えば、単結晶のバルク又は多結晶の粉末）のＧａ２Ｏ３と液体の金属Ｇａである。固体のＧａ２Ｏ３と液体の金属Ｇａは、互いに接触した状態で反応容器２６に収容される。Ｇａ２Ｏ３は１つの塊であっても、粉末であってもよい。 The reaction vessel 26 is made of, for example, quartz glass, and the raw materials for the Ga 2 O 3 suboxide gas contained in the reaction vessel 26 are solid (for example, single crystal bulk or polycrystalline powder) Ga 2 O 3 and liquid. Metal Ga. The solid Ga 2 O 3 and the liquid metal Ga are housed in the reaction vessel 26 in contact with each other. Ga 2 O 3 may be a single mass or a powder.
　なお、β－Ｇａ２Ｏ３系単結晶膜１２として、β－（ＧａｘＡｌ１－ｘ）２Ｏ３（０＜ｘ＜１）単結晶膜を成膜する場合は、Ｇａ２Ｏ３サブオキサイドガスを生成する原料反応領域Ｒ１の他に、Ａｌ２Ｏ３のサブオキサイドのガス（以下、Ａｌ２Ｏ３サブオキサイドガスと呼ぶ）を生成する原料反応領域Ｒ１を備えた気相成長装置２を用いる。Ａｌ２Ｏ３サブオキサイドガスを生成する原料反応領域Ｒ１には、Ａｌ２Ｏ３サブオキサイドガスの原料であるＡｌ２Ｏ３と金属Ａｌが収容された反応容器２６が配置される。 When forming a β- (Ga x Al 1-x ) 2 O 3 (0 <x <1) single crystal film as the β-Ga 2 O 3 system single crystal film 12, the Ga 2 O 3 sub Gas phase growth apparatus 2 provided with a raw material reaction region R1 for producing an Al 2 O 3 suboxide gas (hereinafter referred to as Al 2 O 3 suboxide gas ) in addition to the raw material reaction region R1 for producing an oxide gas. Is used. In the raw material reaction region R1 for producing the Al 2 O 3 suboxide gas, a reaction vessel 26 containing Al 2 O 3 which is a raw material of the Al 2 O 3 suboxide gas and the metal Al is arranged.
　また、β－Ｇａ２Ｏ３系単結晶膜１２として、β－（ＧａｘＩｎ１－ｘ）２Ｏ３（０＜ｘ＜１）単結晶膜を成膜する場合は、Ｇａ２Ｏ３サブオキサイドガスを生成する原料反応領域Ｒ１の他に、Ｉｎ２Ｏ３のサブオキサイドのガス（以下、Ｉｎ２Ｏ３サブオキサイドガスと呼ぶ）を生成する原料反応領域Ｒ１を備えた気相成長装置２を用いる。Ｉｎ２Ｏ３サブオキサイドガスを生成する原料反応領域Ｒ１には、Ｉｎ２Ｏ３サブオキサイドガスの原料であるＩｎ２Ｏ３と金属Ｉｎが収容された反応容器２６が配置される。 Further, when a β- (Ga x In 1-x ) 2 O 3 (0 <x <1) single crystal film is formed as the β-Ga 2 O 3 system single crystal film 12, the Ga 2 O 3 sub is formed. A vapor phase growth apparatus 2 provided with a raw material reaction region R1 for producing an In 2 O 3 suboxide gas (hereinafter referred to as In 2 O 3 suboxide gas ) in addition to the raw material reaction region R1 for producing an oxide gas. Is used. In the raw material reaction region R1 for producing the In 2 O 3 suboxide gas, a reaction vessel 26 containing In 2 O 3 which is a raw material of the In 2 O 3 suboxide gas and the metal In is arranged.
　第１の加熱手段２７と第２の加熱手段２８は、反応チャンバー２０の原料反応領域Ｒ１と結晶成長領域Ｒ２をそれぞれ加熱することができる。第１の加熱手段２７及び第２の加熱手段２８は、例えば、抵抗加熱式や輻射加熱式の加熱装置である。 The first heating means 27 and the second heating means 28 can heat the raw material reaction region R1 and the crystal growth region R2 of the reaction chamber 20, respectively. The first heating means 27 and the second heating means 28 are, for example, resistance heating type or radiant heating type heating devices.
　第１のガス導入ポート２１は、生成されるサブオキサイドガスを運ぶためのキャリアガスを反応チャンバー２０の原料反応領域Ｒ１内に導入するためのポートである。第２のガス導入ポート２２は、酸素の原料ガスであるＯ２ガスをそのキャリアガスとともに結晶成長領域Ｒ２へ導入するためのポートである。第３のガス導入ポート２３は、キャリアガス、及び必要に応じてＳｉＣｌ４などの意図的に添加するドーパントの原料ガスを反応チャンバー２０の結晶成長領域Ｒ２へ導入するためのポートである。 The first gas introduction port 21 is a port for introducing a carrier gas for carrying the generated suboxide gas into the raw material reaction region R1 of the reaction chamber 20. The second gas introduction port 22 is a port for introducing O 2 gas, which is a raw material gas for oxygen, into the crystal growth region R2 together with the carrier gas. The third gas introduction port 23 is a port for introducing a carrier gas and, if necessary, a raw material gas of a dopant intentionally added such as SiC4 into the crystal growth region R2 of the reaction chamber 20.
　第１のガス導入ポート２１、第２のガス導入ポート２２、及び第３のガス導入ポート２３から導入されるキャリアガスは、Ｎ２ガス、Ａｒガスなどの不活性ガスである。Ｎがβ－Ｇａ２Ｏ３系単結晶膜１２中に混入するとアクセプタとして働くおそれがあるが、原料供給分圧、温度などの条件を調整することにより、β－Ｇａ２Ｏ３系単結晶膜１２への混入を防ぐことができる。一方、Ａｒはβ－Ｇａ２Ｏ３系単結晶膜１２中に混入してもドーパントとして働かないため、Ａｒガスをキャリアガスとして用いることが好ましい。 The carrier gas introduced from the first gas introduction port 21, the second gas introduction port 22, and the third gas introduction port 23 is an inert gas such as N2 gas or Ar gas. If N is mixed in the β-Ga 2 O 3 system single crystal film 12, it may act as an acceptor, but by adjusting the conditions such as the partial pressure of the raw material supply and the temperature, the β-Ga 2 O 3 system single crystal film It is possible to prevent contamination with 12. On the other hand, since Ar does not act as a dopant even if it is mixed in the β - Ga 2 O3 system single crystal film 12, it is preferable to use Ar gas as a carrier gas.
（β－Ｇａ２Ｏ３系単結晶膜の成長）
　以下に、本実施の形態に係るβ－Ｇａ２Ｏ３系単結晶膜１２としてのβ－Ｇａ２Ｏ３単結晶膜の成長工程の一例について説明する。 (Growth of β-Ga 2 O 3 series single crystal film)
Hereinafter, an example of the growth step of the β-Ga 2 O 3 single crystal film as the β-Ga 2 O 3 system single crystal film 12 according to the present embodiment will be described.
　まず、第１の加熱手段２７を用いて反応チャンバー２０の原料反応領域Ｒ１を加熱し、原料反応領域Ｒ１の雰囲気温度を所定の温度、例えば８００℃以上、に保つ。原料反応領域Ｒ１の雰囲気温度を８００℃以上にすることにより、Ｇａ２Ｏ３サブオキサイドガスの供給分圧をＨＶＰＥ法のＧａ原料ガスの供給分圧と同程度にすることができる。β－Ｇａ２Ｏ３系単結晶膜１２の成長速度は、このＧａ２Ｏ３サブオキサイドガスの供給分圧に比例する。また、原料反応領域Ｒ１の雰囲気温度は、反応チャンバー２０や反応容器２６の軟化点（例えば、石英ガラス製であれば約１２００℃）よりも低く設定される。 First, the raw material reaction region R1 of the reaction chamber 20 is heated by using the first heating means 27, and the atmospheric temperature of the raw material reaction region R1 is kept at a predetermined temperature, for example, 800 ° C. or higher. By setting the atmospheric temperature of the raw material reaction region R1 to 800 ° C. or higher, the supply partial pressure of the Ga 2 O 3 suboxide gas can be made to be about the same as the supply partial pressure of the Ga raw material gas of the HVPE method. The growth rate of the β-Ga 2 O 3 system single crystal film 12 is proportional to the supply partial pressure of this Ga 2 O 3 suboxide gas. Further, the atmospheric temperature of the raw material reaction region R1 is set lower than the softening point of the reaction chamber 20 and the reaction vessel 26 (for example, about 1200 ° C. if made of quartz glass).
　次に、原料反応領域Ｒ１において、上記の雰囲気温度下で反応容器２６内のＧａ２Ｏ３と金属Ｇａを反応させ、Ｇａ２Ｏ３サブオキサイドガスを生成する。Ｇａ２Ｏ３サブオキサイドガスであるＧａ２ＯガスとＧａＯガスは、それぞれ以下の式１、式２に示される化学反応により生成される。 Next, in the raw material reaction region R1, Ga 2 O 3 in the reaction vessel 26 is reacted with the metal Ga under the above-mentioned atmospheric temperature to generate Ga 2 O 3 suboxide gas. Ga 2 O gas and Ga O gas, which are Ga 2 O 3 suboxide gases, are produced by the chemical reactions represented by the following formulas 1 and 2, respectively.
Figure JPOXMLDOC01-appb-M000001
Figure JPOXMLDOC01-appb-M000001
Figure JPOXMLDOC01-appb-M000002
Figure JPOXMLDOC01-appb-M000002
　式１、式２に示されるように、Ｇａ２Ｏ３サブオキサイドガスの生成には、β－Ｇａ２Ｏ３系単結晶膜１２中でドーパントとして働くＣｌやＣなどの元素を含む原料が用いられない。そのため、Ｇａ２Ｏガスの生成に伴って、β－Ｇａ２Ｏ３系単結晶膜１２中でドーパントとして働く元素を含む物質が生じることがない。 As shown in Formulas 1 and 2, raw materials containing elements such as Cl and C that act as dopants in the β-Ga 2 O 3 system single crystal film 12 are used to generate the Ga 2 O 3 suboxide gas. I can't. Therefore, with the generation of Ga 2 O gas, a substance containing an element acting as a dopant is not generated in the β-Ga 2 O 3 system single crystal film 12.
　Ｇａ２Ｏ３と金属Ｇａは蒸気圧が低いため、それぞれ固体と液体であるが、これらの反応により生成されるＧａ２ＯとＧａＯは、Ｇａ２Ｏ３と金属Ｇａよりも蒸気圧が高く、気体となる。この原料との蒸気圧の差により、高純度のＧａ２ＯガスとＧａＯガス、すなわちＧａ２Ｏ３サブオキサイドガスが得られる。 Ga 2 O 3 and metal Ga are solid and liquid, respectively, because of their low vapor pressure, but Ga 2 O and Ga O produced by these reactions have higher vapor pressure than Ga 2 O 3 and metal Ga. It becomes a gas. Due to the difference in vapor pressure from this raw material, high-purity Ga 2 O gas and Ga O gas, that is, Ga 2 O 3 suboxide gas can be obtained.
　図３は、接触したＧａ２Ｏ３と金属Ｇａを熱することで生成されるサブオキサイドガス中のＧａ２ＯガスとＧａＯガスの分圧と温度の関係を示すグラフである。図３に示されるように、Ｇａ２Ｏ３サブオキサイドガス中のＧａＯガスの濃度はＧａ２Ｏガスの濃度に比較して無視できるくらい低い。すなわち、Ｇａ２Ｏ３サブオキサイドガスは、ほぼＧａ２Ｏガスによって構成される。 FIG. 3 is a graph showing the relationship between the partial pressure and temperature of Ga 2 O gas and Ga O gas in the suboxide gas generated by heating the contacted Ga 2 O 3 and the metal Ga. As shown in FIG. 3 , the concentration of GaO gas in the Ga2O3 suboxide gas is negligibly low compared to the concentration of Ga2O gas. That is, the Ga 2 O 3 suboxide gas is substantially composed of Ga 2 O gas.
　Ｇａ２ＯガスとＧａＯガスの分圧は、Ｇａ２Ｏ３と金属Ｇａの混合（接触）が十分であれば、ほぼ原料反応領域Ｒ１の雰囲気温度のみで決定される。このため、結晶成長領域Ｒ２へのＧａ２Ｏ３サブオキサイドガスの供給量は、原料反応領域Ｒ１の雰囲気温度とＧａ２Ｏ３サブオキサイドガスを運ぶキャリアガスの流量によって決まる。 The partial pressure of Ga 2 O gas and Ga O gas is determined almost exclusively by the atmospheric temperature of the raw material reaction region R1 if the mixture (contact) of Ga 2 O 3 and the metal Ga is sufficient. Therefore, the amount of Ga 2 O 3 suboxide gas supplied to the crystal growth region R2 is determined by the atmospheric temperature of the raw material reaction region R1 and the flow rate of the carrier gas carrying the Ga 2 O 3 suboxide gas.
　生成されたＧａ２Ｏサブオキサイドガスは、第１のガス導入ポート２１から導入されたＡｒガスなどのキャリアガスによって、結晶成長領域Ｒ２へ運ばれる。 The generated Ga 2 O suboxide gas is carried to the crystal growth region R2 by a carrier gas such as Ar gas introduced from the first gas introduction port 21.
　なお、β－Ｇａ２Ｏ３系単結晶膜１２として、β－（ＧａｘＡｌ１－ｘ）２Ｏ３（０＜ｘ＜１）単結晶膜を成膜する場合は、他の原料反応領域Ｒ１において、例えば８００℃以上、反応チャンバー２０や反応容器２６の軟化点未満の雰囲気温度下で反応容器２６内のＡｌ２Ｏ３と金属Ａｌを反応させ、Ａｌ２Ｏ３サブオキサイドガスを生成する。Ａｌ２Ｏ３サブオキサイドガスであるＡｌ２ＯガスとＡｌＯガスは、それぞれ以下の式３、式４に示される化学反応により生成される。 When a β- (Ga x Al 1-x ) 2 O 3 (0 <x <1) single crystal film is formed as the β-Ga 2 O 3 system single crystal film 12, another raw material reaction region is formed. In R1, for example, Al 2 O 3 in the reaction vessel 26 and the metallic Al are reacted with each other at an atmospheric temperature of 800 ° C. or higher and below the softening point of the reaction chamber 20 or the reaction vessel 26 to generate an Al 2 O 3 suboxide gas. .. Al 2 O gas and Al O gas, which are Al 2 O 3 suboxide gases, are produced by the chemical reactions represented by the following formulas 3 and 4, respectively.
Figure JPOXMLDOC01-appb-M000003
Figure JPOXMLDOC01-appb-M000003
Figure JPOXMLDOC01-appb-M000004
Figure JPOXMLDOC01-appb-M000004
　また、β－Ｇａ２Ｏ３系単結晶膜１２として、β－（ＧａｘＩｎ１－ｘ）２Ｏ３（０＜ｘ＜１）単結晶膜を成膜する場合は、他の原料反応領域Ｒ１において、例えば８００℃以上、反応チャンバー２０や反応容器２６の軟化点未満の雰囲気温度下で反応容器２６内のＩｎ２Ｏ３と金属Ｉｎを反応させ、Ｉｎ２Ｏ３サブオキサイドガスを生成する。Ｉｎ２Ｏ３サブオキサイドガスであるＩｎ２ＯガスとＩｎＯガスは、それぞれ以下の式５、式６に示される化学反応により生成される。 Further, when a β- (Ga x In 1-x ) 2 O 3 (0 <x <1) single crystal film is formed as the β-Ga 2 O 3 system single crystal film 12, another raw material reaction region is formed. In R1, for example, In 2 O 3 in the reaction vessel 26 and the metal In are reacted with each other at an atmospheric temperature of 800 ° C. or higher and below the softening point of the reaction chamber 20 or the reaction vessel 26 to generate an In 2 O 3 suboxide gas. .. In 2 O gas and In O gas, which are In 2 O 3 suboxide gases, are produced by the chemical reactions represented by the following formulas 5 and 6, respectively.
Figure JPOXMLDOC01-appb-M000005
Figure JPOXMLDOC01-appb-M000005
Figure JPOXMLDOC01-appb-M000006
Figure JPOXMLDOC01-appb-M000006
　生成されたＡｌ２ＯサブオキサイドガスやＩｎ２Ｏサブオキサイドガスも、Ｇａ２Ｏサブオキサイドガスと同様に、第１のガス導入ポート２１から導入されたＡｒガスなどのキャリアガスによって、結晶成長領域Ｒ２へ運ばれる。 Like the Ga 2 O suboxide gas, the generated Al 2 O suboxide gas and In 2 O suboxide gas also have a crystal growth region due to a carrier gas such as Ar gas introduced from the first gas introduction port 21. It is carried to R2.
　次に、第２の加熱手段２８を用いて加熱された反応チャンバー２０の結晶成長領域Ｒ２において、原料反応領域Ｒ１で生成されたＧａ２Ｏサブオキサイドガスと、第２のガス導入ポート２２から導入されたＯ２ガスとを混合させ、その混合ガスにβ－Ｇａ２Ｏ３系基板１０を曝し、β－Ｇａ２Ｏ３系基板１０の主面１１上にβ－Ｇａ２Ｏ３系単結晶膜１２をエピタキシャル成長させる。β－Ｇａ２Ｏ３系単結晶膜１２を構成するＧａ２Ｏ３は、以下の式７、式８に示される化学反応により生成される。 Next, in the crystal growth region R2 of the reaction chamber 20 heated by the second heating means 28, the Ga 2 O suboxide gas generated in the raw material reaction region R1 is introduced from the second gas introduction port 22. The O 2 gas was mixed, and the β-Ga 2 O 3 system substrate 10 was exposed to the mixed gas, and the β-Ga 2 O 3 system single crystal was placed on the main surface 11 of the β-Ga 2 O 3 system substrate 10. The film 12 is epitaxially grown. Ga 2 O 3 constituting the β-Ga 2 O 3 system single crystal film 12 is produced by a chemical reaction represented by the following formulas 7 and 8.
Figure JPOXMLDOC01-appb-M000007
Figure JPOXMLDOC01-appb-M000007
Figure JPOXMLDOC01-appb-M000008
Figure JPOXMLDOC01-appb-M000008
　β－Ｇａ２Ｏ３系単結晶膜１２の成長温度（結晶成長領域Ｒ２の雰囲気温度）は、８００℃以上であることが好ましい。８００℃よりも低い場合は、準安定相であるα－Ｇａ２Ｏ３やε－Ｇａ２Ｏ３が発生し単結晶が得られないおそれがある。また、β－Ｇａ２Ｏ３系単結晶膜１２の成長圧力（結晶成長領域Ｒ２の雰囲気圧力）は、例えば、およそ１ａｔｍである。また、β－Ｇａ２Ｏ３系単結晶膜１２の成長温度は、Ｇａ２Ｏ３の融点（約１９００℃）と反応チャンバー２０の軟化点（例えば、石英ガラス製であれば約１２００℃）の低い方よりも低く設定される。 The growth temperature of the β - Ga 2 O3 system single crystal film 12 (atmospheric temperature of the crystal growth region R2) is preferably 800 ° C. or higher. If the temperature is lower than 800 ° C., a metastable phase of α-Ga 2 O 3 or ε-Ga 2 O 3 may be generated and a single crystal may not be obtained. The growth pressure of the β - Ga 2 O3 system single crystal film 12 (atmospheric pressure of the crystal growth region R2) is, for example, about 1 atm. The growth temperature of the β-Ga 2 O 3 system single crystal film 12 is the melting point of Ga 2 O 3 (about 1900 ° C.) and the softening point of the reaction chamber 20 (for example, about 1200 ° C. if made of quartz glass). It is set lower than the lower one.
　図４は、本発明の実施の形態に係る方法、ＨＶＰＥ法、及びＴＨＶＰＥ法の各成膜法によるＧａ２Ｏ３の生成反応における平衡定数を示すグラフである。図４の上側の横軸は温度（℃）、下側の横軸は１０００／Ｔ（Ｋ－１）（Ｔは絶対温度）、縦軸はｌｏｇＫ（Ｋは平衡定数）である。図４は、本発明の実施の形態に係る方法は、ＨＶＰＥ法及びＴＨＶＰＥ法よりもＧａ２Ｏ３が生成されやすいことを示している。 FIG. 4 is a graph showing the equilibrium constants in the formation reaction of Ga 2 O 3 by each film forming method of the method according to the embodiment of the present invention, the HVPE method, and the THVPE method. The upper horizontal axis of FIG. 4 is temperature (° C.), the lower horizontal axis is 1000 / T (K -1 ) (T is absolute temperature), and the vertical axis is logK (K is the equilibrium constant). FIG. 4 shows that the method according to the embodiment of the present invention is more likely to generate Ga 2 O 3 than the HVPE method and the THVPE method.
　β－Ｇａ２Ｏ３系単結晶膜１２の成長速度は、成長温度などの成長条件によっておよそ１～１０μｍ／ｈとなることが実証実験により確認されている。この成長速度は、他の結晶成長方法の成長速度と比較して高く、例えば、ＭＢＥ法の数百ｎｍ／ｈ程度の成長速度と比較すると格段に高い。また、実証実験より、さらに成長条件を調整すれば、ＨＶＰＥ法の成長速度（数十μｍ／ｈ）以上になる可能性が十分にあることが確認されている。 It has been confirmed by a demonstration experiment that the growth rate of the β - Ga 2 O3 system single crystal film 12 is about 1 to 10 μm / h depending on the growth conditions such as the growth temperature. This growth rate is higher than the growth rate of other crystal growth methods, and is significantly higher than, for example, the growth rate of about several hundred nm / h in the MBE method. Further, from the demonstration experiment, it has been confirmed that there is a sufficient possibility that the growth rate of the HVPE method (several tens of μm / h) or higher can be achieved by further adjusting the growth conditions.
　β－Ｇａ２Ｏ３系単結晶膜１２として、β－（ＧａｘＡｌ１－ｘ）２Ｏ３（０＜ｘ＜１）単結晶膜を成膜する場合は、Ｇａ２ＯサブオキサイドガスとＯ２ガスに加えてＡｌ２Ｏサブオキサイドガスも結晶成長領域Ｒ２に導入する。以下の式９に、（ＧａｘＡｌ１－ｘ）２Ｏ３が生成される主な化学反応を示す。 When forming a β- (Ga x Al 1-x ) 2 O 3 (0 <x <1) single crystal film as the β-Ga 2 O 3 system single crystal film 12, use Ga 2 O suboxide gas. In addition to the O 2 gas, an Al 2 O suboxide gas is also introduced into the crystal growth region R2. The following formula 9 shows the main chemical reactions in which (Ga x Al 1-x ) 2 O 3 is produced.
Figure JPOXMLDOC01-appb-M000009
Figure JPOXMLDOC01-appb-M000009
　β－Ｇａ２Ｏ３系単結晶膜１２として、β－（ＧａｘＩｎ１－ｘ）２Ｏ３（０＜ｘ＜１）単結晶膜を成膜する場合は、Ｇａ２ＯサブオキサイドガスとＯ２ガスに加えてＩｎ２Ｏサブオキサイドガスも結晶成長領域Ｒ２に導入する。以下の式１０に、（ＧａｘＩｎ１－ｘ）２Ｏ３が生成される主な化学反応を示す。 When forming a β- (Ga x In 1-x ) 2 O 3 (0 <x <1) single crystal film as the β-Ga 2 O 3 system single crystal film 12, use Ga 2 O suboxide gas. In addition to the O 2 gas, an In 2 O suboxide gas is also introduced into the crystal growth region R2. Equation 10 below shows the main chemical reactions that produce (Ga x In 1-x ) 2 O 3 .
Figure JPOXMLDOC01-appb-M000010
Figure JPOXMLDOC01-appb-M000010
　なお、上記の工程を経てβ－Ｇａ２Ｏ３系単結晶膜１２を得た後、β－Ｇａ２Ｏ３系基板１０の厚さ方向の電気抵抗を低下させるために、研磨などの手段を用いてβ－Ｇａ２Ｏ３系基板１０を薄くしてもよい。また、上記の工程を経て得られたβ－Ｇａ２Ｏ３系単結晶膜１２を、研磨などの手段を用いてβ－Ｇａ２Ｏ３系基板１０から切り離してもよい。 After obtaining the β-Ga 2 O 3 system single crystal film 12 through the above steps, a means such as polishing is used to reduce the electrical resistance of the β-Ga 2 O 3 system substrate 10 in the thickness direction. The β-Ga 2 O 3 system substrate 10 may be thinned by using it. Further, the β-Ga 2 O 3 system single crystal film 12 obtained through the above steps may be separated from the β-Ga 2 O 3 system substrate 10 by means such as polishing.
（実施の形態の効果）
　上記本発明の実施の形態によれば、β－Ｇａ２Ｏ３系単結晶膜１２の原料であるＧａ２Ｏ３サブオキサイドガス、Ａｌ２Ｏ３サブオキサイドガス、Ｉｎ２Ｏ３サブオキサイドガスやＯ２ガス、キャリアガスである不活性ガスに、β－Ｇａ２Ｏ３系単結晶膜１２中でドーパントとして機能するＣｌ、Ｃなどの不純物が含まれず、また、上記サブオキサイドガスの原料であるＧａ２Ｏ３、Ａｌ２Ｏ３、Ｉｎ２Ｏ３、金属Ｇａ、金属Ａｌ、金属Ｉｎにもβ－Ｇａ２Ｏ３系単結晶膜１２中でドーパントとして機能するＣｌ、Ｃなどの不純物が含まれないため、サブオキサイドガスの生成に伴ってβ－Ｇａ２Ｏ３系単結晶膜１２中でドーパントとして機能する不純物を含む物質が生成されることがない。このため、β－Ｇａ２Ｏ３系単結晶膜１２中のドーパントとして機能する不純物の濃度が非常に低く、ショットキーバリアダイオードなどの高耐圧を要するデバイスの材料にβ－Ｇａ２Ｏ３系単結晶膜１２を用いることにより、非常に高い耐圧を得ることができる。 (Effect of embodiment)
According to the above-described embodiment of the present invention, Ga 2 O 3 suboxide gas, Al 2 O 3 suboxide gas, In 2 O 3 suboxide gas, which are raw materials for the β-Ga 2 O 3 system single crystal film 12, and the like. The O 2 gas and the inert gas, which is a carrier gas, do not contain impurities such as Cl and C that function as dopants in the β-Ga 2 O 3 system single crystal film 12, and are the raw materials for the suboxide gas. Ga 2 O 3 , Al 2 O 3 , In 2 O 3 , metal Ga, metal Al, and metal In also contain impurities such as Cl and C that function as dopants in the β-Ga 2 O 3 system single crystal film 12. Therefore, a substance containing an impurity that functions as a dopant is not generated in the β - Ga 2 O3 system single crystal film 12 with the generation of the suboxide gas. Therefore, the concentration of impurities that function as dopants in the β-Ga 2 O 3 system single crystal film 12 is extremely low, and β-Ga 2 O 3 system singles are used as materials for devices that require high withstand voltage, such as Schottky barrier diodes. By using the crystal film 12, a very high withstand voltage can be obtained.
　また、上記本発明の実施の形態に係るβ－Ｇａ２Ｏ３系単結晶膜１２の製造方法は、β－Ｇａ２Ｏ３系単結晶膜１２の成長速度にも優れるため、適用するデバイスの特性上、β－Ｇａ２Ｏ３系単結晶膜１２にある程度の厚さが求められる場合であっても、生産現場において現実的な時間でβ－Ｇａ２Ｏ３系単結晶膜１２を形成することができる。 Further, the method for producing the β-Ga 2 O 3 system single crystal film 12 according to the embodiment of the present invention is also excellent in the growth rate of the β-Ga 2 O 3 system single crystal film 12, and therefore, the device to be applied. Even if the β-Ga 2 O 3 system single crystal film 12 is required to have a certain thickness due to its characteristics, the β-Ga 2 O 3 system single crystal film 12 is formed in a realistic time at the production site. be able to.
　図５は、結晶積層構造体１の二次イオン質量分析法（ＳＩＭＳ）による元素分析の測定結果を示すグラフである。本実施例では、β－Ｇａ２Ｏ３系基板１０としてβ－Ｇａ２Ｏ３単結晶基板を、β－Ｇａ２Ｏ３系単結晶膜１２としてβ－Ｇａ２Ｏ３単結晶膜を用いた。図５には、β－Ｇａ２Ｏ３系単結晶膜１２中でドーパントとして働く不純物元素Ｃｌ、Ｓｎ、Ｓｉの濃度が示されている。 FIG. 5 is a graph showing the measurement results of elemental analysis of the crystal laminated structure 1 by the secondary ion mass spectrometry (SIMS). In this embodiment, a β-Ga 2 O 3 single crystal substrate was used as the β-Ga 2 O 3 system substrate 10, and a β-Ga 2 O 3 single crystal film was used as the β-Ga 2 O 3 system single crystal film 12. .. FIG. 5 shows the concentrations of the impurity elements Cl, Sn, and Si that act as dopants in the β - Ga 2 O3 system single crystal film 12.
　図５の横軸はβ－Ｇａ２Ｏ３単結晶膜の表面（結晶積層構造体１の表面）からの深さ（μｍ）であり、縦軸は各元素の濃度（／ｃｍ３）である。また、グラフ右側の点線は、各元素濃度のバックグラウンド（ＢＧ）レベルを表す。バックグラウンドレベルは、分析装置内に何も収容しない状態で測定した各元素の濃度である。 The horizontal axis of FIG. 5 is the depth (μm) from the surface of the β-Ga 2 O 3 single crystal film (the surface of the crystal laminated structure 1), and the vertical axis is the concentration of each element (/ cm 3 ). .. The dotted line on the right side of the graph represents the background (BG) level of each element concentration. The background level is the concentration of each element measured with nothing contained in the analyzer.
　グラフ上側に“β－Ｇａ２Ｏ３単結晶膜”、“基板”で示される深さ方向の範囲は、それぞれβ－Ｇａ２Ｏ３単結晶膜、Ｓｎをドーパントとして含むβ－Ｇａ２Ｏ３系基板１０の測定領域を示す。なお、β－Ｇａ２Ｏ３単結晶膜の表面近傍の各元素の濃度の立ち上がりは、表面吸着物の影響によるものであり、内部の各元素の濃度を示すものではない。 The range in the depth direction indicated by "β-Ga 2 O 3 single crystal film" and "substrate" on the upper side of the graph includes β - Ga 2 O 3 single crystal film and Sn as dopants , respectively. The measurement area of the system substrate 10 is shown. The rise in the concentration of each element near the surface of the β-Ga 2 O 3 single crystal film is due to the influence of the surface adsorbent, and does not indicate the concentration of each element inside.
　図５によれば、β－Ｇａ２Ｏ３単結晶膜中のＣｌの濃度は、バックグラウンドの濃度である５×１０１４／ｃｍ３と一致しており、ＳＩＭＳ装置の検出限界以下、すなわち５×１０１４／ｃｍ３以下であることがわかる。 According to FIG. 5, the concentration of Cl in the β-Ga 2 O 3 single crystal film is consistent with the background concentration of 5 × 10 14 / cm 3 , which is below the detection limit of the SIMS apparatus, that is, 5 It can be seen that it is × 10 14 / cm 3 or less.
　また、β－Ｇａ２Ｏ３単結晶膜中のＣの濃度は、バックグラウンドの濃度である２×１０１６／ｃｍ３と一致しており、ＳＩＭＳ装置の検出限界以下、すなわち２×１０１６／ｃｍ３以下であることがわかる。 In addition, the concentration of C in the β-Ga 2 O 3 single crystal film is consistent with the background concentration of 2 × 10 16 / cm 3 , which is below the detection limit of the SIMS device, that is, 2 × 10 16 /. It can be seen that it is cm 3 or less.
　また、β－Ｇａ２Ｏ３単結晶膜中のＳｎの濃度は、バックグラウンドの濃度である１×１０１５／ｃｍ３と一致しており、ＳＩＭＳ装置の検出限界以下、すなわち１×１０１５／ｃｍ３以下であることがわかる。 Further, the concentration of Sn in the β-Ga 2 O 3 single crystal film is consistent with the background concentration of 1 × 10 15 / cm 3 , which is below the detection limit of the SIMS device, that is, 1 × 10 15 /. It can be seen that it is cm 3 or less.
　また、β－Ｇａ２Ｏ３単結晶膜中のＳｉの濃度は、バックグラウンドの濃度である５×１０１５／ｃｍ３と一致しており、ＳＩＭＳ装置の検出限界以下、すなわち５×１０１５／ｃｍ３以下であることがわかる。 In addition, the concentration of Si in the β-Ga 2 O 3 single crystal film is consistent with the background concentration of 5 × 10 15 / cm 3 , which is below the detection limit of the SIMS device, that is, 5 × 10 15 /. It can be seen that it is cm 3 or less.
　また、β－Ｇａ２Ｏ３単結晶膜中のＦの濃度は、バックグラウンドの濃度である１×１０１４／ｃｍ３と一致しており、ＳＩＭＳ装置の検出限界以下、すなわち１×１０１４／ｃｍ３以下であることがわかる。 In addition, the concentration of F in the β-Ga 2 O 3 single crystal film is consistent with the background concentration of 1 × 10 14 / cm 3 , which is below the detection limit of the SIMS device, that is, 1 × 10 14 /. It can be seen that it is cm 3 or less.
　これらの非常に低いＣｌ、Ｃ、Ｓｎ、Ｓｉ、Ｆの濃度は、β－Ｇａ２Ｏ３単結晶膜の原料であるＧａ２Ｏ３サブオキサイドガスとＯ２ガス、Ｇａ２Ｏ３サブオキサイドガスの原料であるＧａ２Ｏ３と金属Ｇａ、及びキャリアガスである不活性ガスにＣｌ、Ｃ、Ｓｎ、Ｓｉ、Ｆが含まれないことによる。 These very low concentrations of Cl, C, Sn, Si, and F are Ga 2 O 3 suboxide gas and O 2 gas, Ga 2 O 3 suboxide gas, which are the raw materials for the β-Ga 2 O 3 single crystal film. This is because Ga 2 O 3 and metal Ga, which are the raw materials of the above, and the inert gas, which is the carrier gas, do not contain Cl, C, Sn, Si, and F.
　なお、β－Ｇａ２Ｏ３単結晶膜の成膜に用いた気相成長装置２の反応チャンバー２０と反応容器２６は石英ガラス（ＳｉＯ２）製であり、Ｓｉを含むが、上述のβ－Ｇａ２Ｏ３系単結晶膜１２中のＳｉの濃度から、反応チャンバー２０と反応容器２６に含まれるＳｉのβ－Ｇａ２Ｏ３単結晶膜への混入はほとんどなかったと考えられる。 The reaction chamber 20 and the reaction vessel 26 of the vapor phase growth apparatus 2 used for forming the β-Ga 2 O 3 single crystal film are made of quartz glass (SiO 2 ) and contain Si, but the above-mentioned β- From the concentration of Si in the Ga 2 O 3 system single crystal film 12, it is considered that Si contained in the reaction chamber 20 and the reaction vessel 26 was hardly mixed in the β-Ga 2 O 3 single crystal film.
　また、β－Ｇａ２Ｏ３単結晶膜のエピタキシャル結晶成長の下地であるβ－Ｇａ２Ｏ３系基板１０がドーパントとして濃度が約５×１０１８／ｃｍ３のＳｎを含んでいたが、上述のβ－Ｇａ２Ｏ３単結晶膜中のＳｎの濃度から、β－Ｇａ２Ｏ３系基板１０に含まれるＳｎのβ－Ｇａ２Ｏ３単結晶膜への混入はほとんどなかったと考えられる。 Further, the β-Ga 2 O 3 system substrate 10, which is the base for the epitaxial crystal growth of the β-Ga 2 O 3 single crystal film, contained Sn having a concentration of about 5 × 10 18 / cm 3 as a dopant. From the concentration of Sn in the β-Ga 2 O 3 single crystal film, it is considered that Sn contained in the β-Ga 2 O 3 system substrate 10 was hardly mixed in the β-Ga 2 O 3 single crystal film.
　また、β－Ｇａ２Ｏ３単結晶膜のＨの濃度については、ＳＩＭＳ装置のバックグラウンドレベルが２×１０１７／ｃｍ３程度と高く、有意義なデータが取得できないため行っていない。しかしながら、β－Ｇａ２Ｏ３単結晶膜の原料であるＧａ２Ｏ３サブオキサイドガスとＯ２ガス、Ｇａ２Ｏ３サブオキサイドガスの原料であるＧａ２Ｏ３と金属Ｇａ、及びキャリアガスである不活性ガスにはＨが含まれないため、β－Ｇａ２Ｏ３単結晶膜のＨの濃度はバックグラウンドレベルである２×１０１７／ｃｍ３よりも大幅に低いことが推測される。 The concentration of H in the β-Ga 2 O 3 single crystal film is not performed because the background level of the SIMS device is as high as 2 × 10 17 / cm 3 and meaningful data cannot be obtained. However, with Ga 2 O 3 suboxide gas and O 2 gas, which are the raw materials for the β-Ga 2 O 3 single crystal film, Ga 2 O 3 and metal Ga, which are the raw materials for the Ga 2 O 3 suboxide gas, and a carrier gas. Since H is not contained in a certain inert gas, it is presumed that the concentration of H in the β-Ga 2 O 3 single crystal film is significantly lower than the background level of 2 × 10 17 / cm 3 .
　図６は、厚さ３μｍのβ－Ｇａ２Ｏ３単結晶膜の表面モフォロジーの光学顕微鏡による観察像である。図６の観察像によれば、エピタキシャル成長結晶の表面に特有の筋が確認できる。この表面の状態から、ＨＶＰＥ法で成膜したものと遜色ない品質の膜が得られていることがわかる。 FIG. 6 is an observation image of the surface morphology of a β-Ga 2 O 3 single crystal film having a thickness of 3 μm with an optical microscope. According to the observation image of FIG. 6, streaks peculiar to the surface of the epitaxially grown crystal can be confirmed. From this surface condition, it can be seen that a film having a quality comparable to that formed by the HVPE method is obtained.
　なお、本実施例においては、β－Ｇａ２Ｏ３系単結晶膜１２としてβ－Ｇａ２Ｏ３単結晶膜についての評価結果を示したが、他のβ－Ｇａ２Ｏ３系単結晶膜であるβ－（ＧａｘＡｌ１－ｘ）２Ｏ３単結晶膜やβ－（ＧａｘＩｎ１－ｘ）２Ｏ３単結晶膜を評価した場合であっても、β－Ｇａ２Ｏ３単結晶膜と同様にドーパントとして働く不純物の意図しない混入が抑えられているため、同様の評価結果が得られる。 In this example, the evaluation results of the β-Ga 2 O 3 single crystal film as the β-Ga 2 O 3 system single crystal film 12 are shown, but other β-Ga 2 O 3 system single crystal films are shown. Even when β- (Ga x Al 1-x ) 2 O 3 single crystal film or β- (Ga x In 1-x ) 2 O 3 single crystal film is evaluated, β-Ga 2 O 3 Similar to the single crystal film, the unintentional mixing of impurities acting as dopants is suppressed, so that the same evaluation results can be obtained.
　以上、本発明の実施の形態及び実施例を説明したが、本発明は、上記実施の形態及び実施例に限定されず、発明の主旨を逸脱しない範囲内において種々変形実施が可能である。 Although the embodiments and examples of the present invention have been described above, the present invention is not limited to the above embodiments and examples, and various modifications can be carried out within a range that does not deviate from the gist of the invention.
　また、上記に記載した実施の形態及び実施例は特許請求の範囲に係る発明を限定するものではない。また、実施の形態及び実施例の中で説明した特徴の組合せの全てが発明の課題を解決するための手段に必須であるとは限らない点に留意すべきである。 Further, the embodiments and examples described above do not limit the invention according to the claims. It should also be noted that not all combinations of features described in embodiments and examples are essential to the means for solving the problems of the invention.
　結晶成長速度が大きく、かつドーパントとして働く不純物の意図しない混入を抑えることのできるβ－Ｇａ２Ｏ３系単結晶膜の製造方法、及びその方法により製造されたβ－Ｇａ２Ｏ３系単結晶膜を提供する。 A method for producing a β-Ga 2 O 3 series single crystal film that has a high crystal growth rate and can suppress unintentional mixing of impurities that act as dopants, and a β-Ga 2 O 3 series single crystal produced by that method. Provides a membrane.
１…結晶積層構造体、１０…β－Ｇａ２Ｏ３系基板、１１…主面、１２…β－Ｇａ２Ｏ３系単結晶膜、２…気相成長装置 1 ... Crystal laminated structure, 10 ... β-Ga 2 O 3 system substrate, 11 ... Main surface, 12 ... β-Ga 2 O 3 system single crystal film, 2 ... Vapor phase growth apparatus

Claims (6)

  1. 　β－Ｇａ２Ｏ３の単結晶、又は、一部のＧａがＡｌ、Ｉｎの一方又は両方で置換されたβ－Ｇａ２Ｏ３の単結晶であるβ－Ｇａ２Ｏ３系単結晶からなるβ－Ｇａ２Ｏ３系単結晶膜の製造方法であって、
    　前記β－Ｇａ２Ｏ３系単結晶膜の中でドーパントとして働く不純物を含む物質の生成を伴わずにＡ２Ｏ３（ＡはＧａ、Ａｌ、又はＩｎ）のサブオキサイドガスを生成する工程と、
    　前記サブオキサイドガスをＯ２ガスと反応させて、基板上に前記β－Ｇａ２Ｏ３系単結晶膜をエピタキシャル成長させる工程と、
    　を含む、β－Ｇａ２Ｏ３系単結晶膜の製造方法。     It consists of a single crystal of β -Ga 2 O 3 or a single crystal of β-Ga 2 O 3 system in which a part of Ga is substituted with one or both of Al and In. A method for producing a β - Ga 2 O3 system single crystal film.
    A step of producing a suboxide gas of A 2 O 3 (A is Ga, Al, or In) without producing a substance containing an impurity that acts as a dopant in the β-Ga 2 O 3 system single crystal film. ,
    A step of reacting the suboxide gas with the O 2 gas to epitaxially grow the β-Ga 2 O 3 system single crystal film on the substrate.
    A method for producing a β - Ga 2 O3 system single crystal film, which comprises.
  2. 　前記サブオキサイドガスを生成する工程において、Ｇａ２Ｏ３のサブオキサイドガスをＧａ２Ｏ３と金属Ｇａを反応させて生成し、Ａｌ２Ｏ３のサブオキサイドガスを生成する場合はＡｌ２Ｏ３と金属Ａｌを反応させて生成し、Ｉｎ２Ｏ３のサブオキサイドガスを生成する場合はＩｎ２Ｏ３と金属Ｉｎを反応させて生成する、
    　請求項１に記載のβ－Ｇａ２Ｏ３系単結晶膜の製造方法。     In the step of producing the suboxide gas, the suboxide gas of Ga 2 O 3 is produced by reacting Ga 2 O 3 with the metal Ga, and when the suboxide gas of Al 2 O 3 is produced, Al 2 O 3 is produced. And metal Al are reacted to generate In 2 O 3 suboxide gas, and In 2 O 3 is reacted with metal In to generate.
    The method for producing a β - Ga 2 O3 system single crystal film according to claim 1.
  3. 　前記サブオキサイドガスを生成する工程において、８００℃以上の雰囲気温度下で前記サブオキサイドガスを生成する、
    　請求項１又は２に記載のβ－Ｇａ２Ｏ３系単結晶膜の製造方法。     In the step of producing the suboxide gas, the suboxide gas is generated under an atmospheric temperature of 800 ° C. or higher.
    The method for producing a β - Ga 2 O3 system single crystal film according to claim 1 or 2.
  4. 　前記β－Ｇａ２Ｏ３系単結晶膜をエピタキシャル成長させる工程において、８００℃以上の雰囲気温度下で前記β－Ｇａ２Ｏ３系単結晶膜をエピタキシャル成長させる、
    　請求項１～３のいずれか１項に記載のβ－Ｇａ２Ｏ３系単結晶膜の製造方法。     In the step of epitaxially growing the β-Ga 2 O 3 system single crystal film, the β-Ga 2 O 3 system single crystal film is epitaxially grown under an atmospheric temperature of 800 ° C. or higher.
    The method for producing a β-Ga 2 O3 system single crystal film according to any one of claims 1 to 3 .
  5. 　β－Ｇａ２Ｏ３の単結晶、又は、一部のＧａがＡｌ、Ｉｎの一方又は両方で置換されたβ－Ｇａ２Ｏ３の単結晶であるβ－Ｇａ２Ｏ３系単結晶からなり、
    　Ｃｌの濃度が５×１０１４／ｃｍ３以下、Ｃの含有量が２×１０１６／ｃｍ３以下である、
    　β－Ｇａ２Ｏ３系単結晶膜。     It consists of a single crystal of β - Ga 2 O 3 or a single crystal of β - Ga 2 O 3 in which a part of Ga is substituted with one or both of Al and In. ,
    The concentration of Cl is 5 × 10 14 / cm 3 or less, and the content of C is 2 × 10 16 / cm 3 or less.
    β-Ga 2 O 3 series single crystal film.
  6. 　Ｓｎの含有量が１×１０１５／ｃｍ３以下、Ｓｉの含有量が５×１０１５／ｃｍ３以下、Ｆの含有量が１×１０１４／ｃｍ３以下である、
    　請求項５に記載のβ－Ｇａ２Ｏ３系単結晶膜。     The Sn content is 1 × 10 15 / cm 3 or less, the Si content is 5 × 10 15 / cm 3 or less, and the F content is 1 × 10 14 / cm 3 or less.
    The β - Ga 2 O3 system single crystal film according to claim 5.
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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2024010637A1 (en) * 2022-07-06 2024-01-11 Ohio State Innovation Foundation Compositions comprising gallium oxide doped with carbon, and methods of making and use thereof

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5904553A (en) * 1997-08-25 1999-05-18 Motorola, Inc. Fabrication method for a gate quality oxide-compound semiconductor structure
JP2004182546A (en) * 2002-12-04 2004-07-02 National Institute For Materials Science beta-Ga2O3 NANO WHISKER AND ITS MANUFACTURING METHOD
JP2006089811A (en) * 2004-09-24 2006-04-06 Hokkaido Univ Vapor phase crystal creation apparatus
WO2016031522A1 (en) * 2014-08-29 2016-03-03 株式会社タムラ製作所 Semiconductor element and production method for same

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5904553A (en) * 1997-08-25 1999-05-18 Motorola, Inc. Fabrication method for a gate quality oxide-compound semiconductor structure
JP2004182546A (en) * 2002-12-04 2004-07-02 National Institute For Materials Science beta-Ga2O3 NANO WHISKER AND ITS MANUFACTURING METHOD
JP2006089811A (en) * 2004-09-24 2006-04-06 Hokkaido Univ Vapor phase crystal creation apparatus
WO2016031522A1 (en) * 2014-08-29 2016-03-03 株式会社タムラ製作所 Semiconductor element and production method for same

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
GAO Y. H., BANDO Y., SATO T., ZHANG Y. F., GAO X. Q.: "Synthesis, Raman scattering and defects of β-Ga2O3 nanorods", APPLIED PHYSICS LETTERS, AMERICAN INSTITUTE OF PHYSICS, 2 HUNTINGTON QUADRANGLE, MELVILLE, NY 11747, vol. 81, no. 12, 16 September 2002 (2002-09-16), 2 Huntington Quadrangle, Melville, NY 11747, pages 2267 - 2269, XP012031974, ISSN: 0003-6951, DOI: 10.1063/1.1507835 *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2024010637A1 (en) * 2022-07-06 2024-01-11 Ohio State Innovation Foundation Compositions comprising gallium oxide doped with carbon, and methods of making and use thereof

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