# US 11,028,474 B2 · Method for cleaning SiC monocrystal growth furnace > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,028,474 B2 - Document ID: US11028474B2 - Status: Granted - Kind: B2 - Application number: 16/065,257 - Filed: 2016-12-26 - Published: 2019-01-03 - Granted: 2021-06-08 - Earliest claimed: 2015-12-28 - Assignees: Showa Denko K.K. - Applicants: Showa Denko K.K. - Inventors: Yosuke Tanimoto; Hideyuki Kurihara - Web page: https://patentgrep.com/patent/US11028474B2 ## CPC - C23C 16/4405: {Cleaning of reactor or parts inside the reactor by using reactive gases} - B08B 5/00: Cleaning by methods involving the use of air flow or gas flow (cleaning hollow articles by methods or apparatus specially adapted thereto B08B9/00) - B08B 9/00: Cleaning hollow articles by methods or apparatus specially adapted thereto - C23C 14/564: {Means for minimising impurities in the coating chamber such as dust, moisture, residual gases} - C30B 23/00: Single-crystal growth by condensing evaporated or sublimed materials - C30B 29/36: Carbides - C30B 25/02: Epitaxial-layer growth - 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 (making metal-coated products by extrusion B21C23/22; covering with metal by connecting pre-existing layers to articles, see the relevant places, e.g. B21D39/00, B23K; metallising of glass C03C; metallising mortars, concrete, artificial stone, ceramics or natural stone C04B41/00; enamelling of, or applying a vitreous layer to, metals C23D; treating metal surfaces or coating of metals by electrolysis or electrophoresis C25D; single-crystal film growth C30B; by metallising textiles D06M11/83; decorating textiles by locally metallising D06Q1/04) - B08B: CLEANING IN GENERAL; PREVENTION OF FOULING IN GENERAL - C30B: SINGLE-CRYSTAL GROWTH (by using ultra-high pressure, e.g. for the formation of diamonds, B01J3/06); UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL (zone-refining of metals or alloys C22B); PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE (casting of metals, casting of other substances by the same processes or devices B22D; working of plastics B29; modifying the physical structure of metals or alloys C21D, C22F); SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE (for producing semiconductor devices or parts thereof H10); APPARATUS THEREFOR ## Abstract A method of cleaning a SiC monocrystal growth furnace provided with an in-furnace substrate composed of a 3C-SiC polycrystal having at least a surface in which an intensity ratio of a (111) plane with respect to other crystal planes is at least 85% but not more than 100% according to powder XRD analysis, the method including flowing a mixed gas of fluorine gas and at least one of an inert gas and air in a non-plasma state through the inside of the SiC monocrystal growth furnace, thereby selectively removing a SiC deposit deposited inside the SiC monocrystal growth furnace, wherein the mixed gas comprises at least 1 vol % but not more than 20 vol % of fluorine gas, and at least 80 vol % but not more than 99 vol % of an inert gas, and a temperature inside the SiC monocrystal growth furnace is from 200° C. to 500° C. ## Claims ### Claim 1 A method of cleaning a SiC monocrystal growth furnace using a gas to clean a SiC monocrystal growth furnace provided with an in-furnace substrate composed of a 3C—SiC polycrystal having at least a surface in which an intensity ratio of a (111) plane with respect to other crystal planes is at least 85% but not more than 100% according to powder XRD analysis, the method comprising: flowing a mixed gas which consists of F2 gas and an inert gas in a non-plasma state through an inside of the SiC monocrystal growth furnace, thereby selectively removing a SiC deposit deposited inside the SiC monocrystal growth furnace, wherein the SiC deposit is a 3C—SiC polycrystal having an intensity ratio of the (111) plane with respect to the other crystal planes of less than 85% according to powder XRD analysis, and wherein the mixed gas comprises at least 1 vol % but not more than 20 vol % of F2 gas, and at least 80 vol % but not more than 99 vol % of the inert gas, wherein a temperature of the inside the SiC monocrystal growth furnace is at least 200° C. but not more than 500° C., and wherein the in-furnace substrate comprises an inner wall and members of the SiC monocrystal growth furnace. ### Claim 2 (depends on 1) The method of cleaning a SiC monocrystal growth furnace according to claim 1, wherein a temperature inside the SiC monocrystal growth furnace is 280° C.-400° C. ### Claim 3 (depends on 1) The method of cleaning a SiC monocrystal growth furnace according to claim 1, wherein the inert gas is selected from the group consisting of nitrogen gas, argon gas and helium gas. ### Claim 4 A method of cleaning a SiC monocrystal growth furnace by using a gas to clean a SiC monocrystal growth furnace provided with an in-furnace substrate composed of a 3C—SiC polycrystal having at least a surface in which an intensity ratio of a (111) plane with respect to other crystal planes is at least 85% but not more than 100% according to powder XRD analysis, the method comprising: flowing a mixed gas in a non-plasma state through an inside of the SiC monocrystal growth furnace, thereby selectively removing a SiC deposit deposited inside the SiC monocrystal growth furnace, wherein the SiC deposit is a 3C—SiC polycrystal having an intensity ratio of the (111) plane with respect to the other crystal planes of less than 85% according to powder XRD analysis, wherein the mixed gas comprises at least 1 vol % but not more than 20 vol % of F2 gas, and at least 80 vol % but not more than 99 vol % of the inert gas, and a temperature of the inside the SiC monocrystal growth furnace is 280° C. 400° C., wherein the in-furnace substrate comprises an inner wall and members of the SiC monocrystal growth furnace, and wherein the mixed gas consists of F2 gas and an inert gas, or consists of F2 gas, an inert gas and air. ### Claim 5 (depends on 4) The method of cleaning a SiC monocrystal growth furnace according to claim 4, wherein the inert gas is nitrogen gas. ### Claim 6 (depends on 4) The method of cleaning a SiC monocrystal growth furnace according to claim 4, wherein the inert gas is selected from the group consisting of nitrogen gas, argon gas and helium gas. ### Claim 7 (depends on 6) The method of cleaning a SiC monocrystal growth furnace according to claim 6, wherein the inert gas is either nitrogen gas or argon gas. ### Claim 8 A method of cleaning a SiC monocrystal growth furnace using a gas to clean a SiC monocrystal growth furnace provided with an in-furnace substrate composed of a 3C—SiC polycrystal having at least a surface in which an intensity ratio of a (111) plane with respect to other crystal planes is at least 85% but not more than 100% according to powder XRD analysis, the method comprising: flowing a mixed gas which consists of F2 gas and at least one of an inert gas and air in a non-plasma state through an inside of the SiC monocrystal growth furnace, thereby selectively removing a SiC deposit deposited inside the SiC monocrystal growth furnace, wherein the SiC deposit is a 3C—SiC polycrystal having an intensity ratio of the (111) plane with respect to the other crystal planes of less than 85% according to powder XRD analysis, wherein the mixed gas comprises at least 1 vol % but not more than 20 vol % of F2 gas, and at least 80 vol % but not more than 99 vol % of the inert gas, and a temperature of the inside the SiC monocrystal growth furnace is at least 200° C. but not more than 500° C., and wherein the in-furnace substrate comprises an inner wall and members of the SiC monocrystal growth furnace. ### Claim 9 (depends on 8) The method of cleaning a SiC monocrystal growth furnace according to claim 8, wherein a temperature inside the SiC monocrystal growth furnace is 280° C. 400° C. ### Claim 10 (depends on 8) The method of cleaning a SiC monocrystal growth furnace according to claim 8, wherein the mixed gas consists of F2 gas, the inert gas and the air. ### Claim 11 (depends on 8) The method of cleaning a SiC monocrystal growth furnace according to claim 8, wherein the inert gas is nitrogen gas. ### Claim 12 (depends on 8) The method of cleaning a SiC monocrystal growth furnace according to claim 8, wherein the mixed gas consists of F2 gas and the inert gas, or consists of F2 gas, the inert gas and the air. ### Claim 13 (depends on 8) The method of cleaning a SiC monocrystal growth furnace according to claim 8, wherein the inert gas is selected from the group consisting of nitrogen gas, argon gas and helium gas. ### Claim 14 (depends on 13) The method of cleaning a SiC monocrystal growth furnace according to claim 13, wherein the inert gas is either nitrogen gas or argon gas.