# US 2014/0360426 A1 · Method for Producing a Group III Nitride Semiconductor Crystal and Method for Producing a GaN Substrate > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0360426 A1 - Document ID: US20140360426A1 - Status: Published application - Kind: A1 - Application number: 14/295,204 - Filed: 2014-06-03 - Published: 2014-12-11 - Earliest claimed: 2013-06-07 - Assignees: Toyoda Gosei Co., Ltd. - Applicants: Toyoda Gosei Co., Ltd. - Inventors: Shohei Kumegawa; Yasuhide Yakushi; Seiji Nagai; Miki Moriyama - Web page: https://patentgrep.com/patent/US20140360426A1 ## CPC - H10P 14/3416: {Nitrides} - H10P 14/26: using liquid deposition - H10P 14/272: {using mask materials other than SiO2 or SiN} - H10P 14/276: {Lateral overgrowth} - H10P 95/11: {Separation of active layers from substrates} - H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10 ## Abstract The present invention provides a method for producing a Group III nitride semiconductor crystal and a GaN substrate, in which the transfer of dislocation density or the occurrence of cracks can be certainly reduced on a growth substrate, and the Group III nitride semiconductor crystal can be easily separated from a seed crystal. A mask layer is formed on a GaN substrate, to thereby form an exposed portion of the GaN substrate, and an unexposed portion of the GaN substrate. Through a flux method, a GaN layer is formed on the exposed portions of the GaN substrate in a molten mixture containing at least Group III metal and Na. At that time, non-crystal portions containing the components of the molten mixture are formed on the mask layer so as to be covered with the GaN layer grown on the GaN substrate and the mask layer. ## Claims ### Claim 1 A method for producing a Group III nitride semiconductor crystal, the method comprising: forming a mask layer on an underlayer, to thereby form an exposed portion of the underlayer which is not covered with the mask layer, and an unexposed portion of the underlayer which is covered with the mask layer; growing a Group III nitride semiconductor crystal on the exposed portion of the underlayer in a molten mixture containing at least Group III metal and Na; and wherein, in growing a Group III nitride semiconductor crystal, the Group III nitride semiconductor crystal is grown on the exposed portion of the underlayer in; and non-crystal portions containing the components of the molten mixture are formed on the mask layer. ### Claim 2 (depends on 1) The method for producing a Group III nitride semiconductor crystal according to claim 1, wherein the exposed portion comprises a plurality of growth starting regions discretely disposed and connecting portions to connect the growth starting regions. ### Claim 3 (depends on 2) The method for producing a Group III nitride semiconductor crystal according to claim 2, wherein the growth starting regions are disposed at vertices of a triangle, and the connecting portions are disposed at positions corresponding to sides of the triangle. ### Claim 4 (depends on 3) The method for producing a Group III nitride semiconductor crystal according to claim 3, wherein the connecting portions are formed with a longitudinal direction thereof oriented at an angle of 5° or less from an m-axis of the underlayer. ### Claim 5 (depends on 1) The method for producing a Group III nitride semiconductor crystal according to claim 1, the method further comprising: forming a first mask layer on the underlayer; growing a first Group III nitride semiconductor crystal on the first mask layer in the molten mixture; forming a second mask layer on the first Group III nitride semiconductor crystal; and growing a second Group III nitride semiconductor crystal on the second mask layer in the molten mixture. ### Claim 6 (depends on 2) The method for producing a Group III nitride semiconductor crystal according to claim 2, the method further comprising: forming a first mask layer on the underlayer; growing a first Group III nitride semiconductor crystal on the first mask layer in the molten mixture; forming a second mask layer on the first Group III nitride semiconductor crystal; and growing a second Group III nitride semiconductor crystal on the second mask layer in the molten mixture. ### Claim 7 (depends on 3) The method for producing a Group III nitride semiconductor crystal according to claim 3, the method further comprising: forming a first mask layer on the underlayer; growing a first Group III nitride semiconductor crystal on the first mask layer in the molten mixture; forming a second mask layer on the first Group III nitride semiconductor crystal; and growing a second Group III nitride semiconductor crystal on the second mask layer in the molten mixture. ### Claim 8 (depends on 4) The method for producing a Group III nitride semiconductor crystal according to claim 4, the method further comprising: forming a first mask layer on the underlayer; growing a first Group III nitride semiconductor crystal on the first mask layer in the molten mixture; forming a second mask layer on the first Group III nitride semiconductor crystal; and growing a second Group III nitride semiconductor crystal on the second mask layer in the molten mixture. ### Claim 9 (depends on 5) The method for producing a Group III nitride semiconductor crystal according to claim 5, wherein the second mask layer is formed at a position perpendicular to a main surface of the mask layer as viewed from the exposed portion of the first mask layer. ### Claim 10 (depends on 7) The method for producing a Group III nitride semiconductor crystal according to claim 7, wherein the second mask layer is formed at a position perpendicular to a main surface of the mask layer as viewed from the exposed portion of the first mask layer. ### Claim 11 (depends on 1) The method for producing a Group III nitride semiconductor crystal according to claim 1, wherein the mask layer is formed through atomic layer deposition. ### Claim 12 (depends on 1) The method for producing a Group III nitride semiconductor crystal according to claim 1, wherein the mask layer comprises Al2O3. ### Claim 13 (depends on 1) The method for producing a Group III nitride semiconductor crystal according to claim 1, wherein the mask layer comprises at least one of ZrO2 and TiO2. ### Claim 14 A method for producing a Group III nitride semiconductor substrate, the method comprising: forming a mask layer on an underlayer, and forming a seed crystal having an exposed portion of the underlayer which is not covered with the mask layer and an unexposed portion of the underlayer which is covered with the mask layer; growing a Group III nitride semiconductor crystal on the exposed portion of the underlayer in a molten mixture containing at least Ga and Na; separating the Group III nitride semiconductor crystal from the seed crystal; and wherein, in forming a semiconductor crystal, the Group III nitride semiconductor crystal is grown on the exposed portions of the underlayer, and non-crystal portions containing the components of the molten mixture are formed on the mask layer. ### Claim 15 (depends on 14) The method for producing a Group III nitride semiconductor substrate according to claim 14, wherein the exposed portion comprises a plurality of growth starting regions discretely disposed and connecting portions to connect the growth starting regions. ### Claim 16 (depends on 15) The method for producing a Group III nitride semiconductor substrate according to claim 15, wherein the growth starting regions are disposed at vertices of a triangle, and the connecting portions are disposed at positions corresponding to sides of the triangle. ### Claim 17 (depends on 16) The method for producing a Group III nitride semiconductor substrate according to claim 16, wherein the connecting portions are formed with a longitudinal direction thereof oriented at an angle of 5° or less from an m-axis of the underlayer. ### Claim 18 (depends on 14) The method for producing a Group III nitride semiconductor substrate according to claim 14, wherein, in separating the Group III nitride semiconductor crystal, when separating the Group III nitride semiconductor crystal from the seed crystal, the components of the molten mixture are removed out from the non-crystal portions.