# US 10,770,552 B2 · Epitaxial substrate for semiconductor elements, semiconductor element, and manufacturing method for epitaxial substrates for semiconductor elements > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,770,552 B2 - Document ID: US10770552B2 - Status: Granted - Kind: B2 - Application number: 16/733,320 - Filed: 2020-01-03 - Published: 2020-05-07 - Granted: 2020-09-08 - Earliest claimed: 2015-11-02 - Assignees: NGK Insulators, Ltd. - Applicants: Ngk Insulators, Ltd. - Inventors: Mikiya Ichimura; Sota Maehara; Yoshitaka Kuraoka - Web page: https://patentgrep.com/patent/US10770552B2 ## CPC - H10D 62/8503: {Nitride Group III-V materials, e.g. AlN or GaN} - C23C 16/303: {Nitrides} - C30B 25/02: Epitaxial-layer growth - C30B 29/38: Nitrides - C30B 29/406: {Gallium nitride} - H10D 30/015: {of FETs having heterojunction interface channels or heterojunction gate electrodes, e.g. HEMT} - H10D 30/47: having two-dimensional [2D] charge carrier gas channels, e.g. nanoribbon FETs or high electron mobility transistors [HEMT] - H10D 30/475: {having wider bandgap layer formed on top of lower bandgap active layer, e.g. undoped barrier HEMTs such as i-AlGaN/GaN HEMTs} - H10D 62/60: Impurity distributions or concentrations - H10D 62/824: comprising only Group III-V materials heterojunctions, e.g. GaN/AlGaN heterojunctions - H10P 14/24: using chemical vapour deposition [CVD] - H10P 14/2908: {Nitrides} - H10P 14/2921: {being crystalline insulating materials} - H10P 14/3216: {Nitrides} - H10P 14/3416: {Nitrides} - H10D 62/854: further characterised by the dopants - H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES - 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) - 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 - H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10 ## Abstract An epitaxial substrate for semiconductor elements suppresses leakage current and has a high breakdown voltage. The epitaxial substrate for semiconductor elements includes: a semi-insulating free-standing substrate formed of GaN doped with Zn; a buffer layer formed of a group 13 nitride adjacent to the free-standing substrate; a channel layer formed of a group 13 nitride adjacent to the buffer layer; and a barrier layer formed of a group 13 nitride on an opposite side of the buffer layer with the channel layer therebetween, wherein part of a first region consisting of the free-standing substrate and the buffer layer is a second region containing Si at a concentration of 1×1017cm−3 or more, and a minimum value of a concentration of Zn in the second region is 1×1017cm−3. ## Claims ### Claim 1 A method of manufacturing an epitaxial substrate for semiconductor elements, comprising: a) a preparation step of preparing a first region consisting of a semi-insulating free-standing substrate formed of GaN being doped with Zn; b) a buffer layer formation step of forming a buffer layer formed of group 13 nitride adjacent to said free-standing substrate; c) a channel layer formation step of forming a channel layer formed of group 13 nitride adjacent to said buffer layer; and d) a barrier layer formation step of forming a barrier layer formed of group 13 nitride in a position opposite to said buffer layer with said channel layer therebetween, wherein a second region containing Si at a concentration of 1×1017cm−3 or more is formed through taking Si in said free-standing substrate, which has been prepared in said preparation step, from outside before said buffer layer formation step is completed, in part of a first region consisting of said free-standing substrate and said buffer layer, and in said buffer layer formation step, Zn is diffused from said free-standing substrate, thereby forming said buffer layer in which a minimum value of a concentration of Zn is 1×1017cm−3 in said second region. ### Claim 2 (depends on 1) The method of manufacturing the epitaxial substrate for the semiconductor elements according to claim 1, wherein said second region exists in said first region, including an interface between said free-standing substrate and said buffer layer. ### Claim 3 (depends on 1) The method of manufacturing the epitaxial substrate for the semiconductor elements according to claim 1, wherein said free-standing substrate is manufactured by a flux method. ### Claim 4 (depends on 1) The method of manufacturing the epitaxial substrate for the semiconductor elements according to claim 1, wherein said buffer layer is formed of GaN, said channel layer is formed of GaN, and said barrier layer is formed of AlGaN. ### Claim 5 (depends on 1) The method of manufacturing the epitaxial substrate for the semiconductor elements according to claim 1, wherein said buffer layer is formed as either of a multi-layered buffer layer which is formed by laminating two or more group 13 nitride layers having different compositions, or a composition gradient buffer layer formed of group 13 nitride containing two or more group 13 elements, each element having an existence ratio changed in a thickness direction, said channel layer is formed of GaN, and said barrier layer is formed of AlGaN. ### Claim 6 (depends on 2) The method of manufacturing the epitaxial substrate for the semiconductor elements according to claim 2, wherein said free-standing substrate is manufactured by a flux method. ### Claim 7 (depends on 2) The method of manufacturing the epitaxial substrate for the semiconductor elements according to claim 2, wherein said buffer layer is formed of GaN, said channel layer is formed of GaN, and said barrier layer is formed of AlGaN. ### Claim 8 (depends on 2) The method of manufacturing the epitaxial substrate for the semiconductor elements according to claim 2, wherein said buffer layer is formed as either of a multi-layered buffer layer which is formed by laminating two or more group 13 nitride layers having different compositions, or a composition gradient buffer layer formed of group 13 nitride containing two or more group 13 elements, each element having an existence ratio changed in a thickness direction, said channel layer is formed of GaN, and said barrier layer is formed of AlGaN.