# US 2019/0355571 A1 · Nitride semiconductor substrate and method for manufacturing same > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2019/0355571 A1 - Document ID: US20190355571A1 - Status: Published application - Kind: A1 - Application number: 16/347,928 - Filed: 2017-11-08 - Published: 2019-11-21 - Earliest claimed: 2016-11-08 - Assignees: Asahi Kasei Kabushiki Kaisha; Meijo University - Applicants: Asahi Kasei Kabushiki Kaisha; Meijo University - Inventors: Akira Yoshikawa; Tomohiro Morishita; Motoaki Iwaya - Web page: https://patentgrep.com/patent/US20190355571A1 ## CPC - H10P 14/24: using chemical vapour deposition [CVD] - H10F 30/21: the devices being sensitive to infrared, visible or ultraviolet radiation - H10F 71/1278: {comprising nitrides, e.g. GaN} - H10F 77/1246: {III-V nitrides, e.g. GaN} - H10F 77/16: Material structures, e.g. crystalline structures, film structures or crystal plane orientations - H10F 77/703: {of the semiconductor bodies, e.g. textured active layers} - H10H 20/01335: {the light-emitting regions comprising nitride materials} - H10H 20/815: having stress relaxation structures, e.g. buffer layers - H10H 20/817: characterised by the crystal structures or orientations, e.g. polycrystalline, amorphous or porous - H10H 20/819: characterised by their shape, e.g. curved or truncated substrates - H10H 20/825: containing nitrogen, e.g. GaN - H10P 14/2921: {being crystalline insulating materials} - H10P 14/2925: {Surface structures} - H10P 14/3216: {Nitrides} - H10P 14/3251: {consisting of three or more layers} - H10P 14/3416: {Nitrides} - H10P 14/3466: {Crystal orientation} - H10F 55/25: wherein the radiation-sensitive devices and the electric light source are all semiconductor devices - H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10 - H10F: INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION - H10H: INORGANIC LIGHT-EMITTING SEMICONDUCTOR DEVICES HAVING POTENTIAL BARRIERS ## Abstract A nitride semiconductor substrate includes a sapphire substrate and a nitride semiconductor layer formed thereon and containing a group III element including Al and nitrogen as a main component. A surface of the sapphire substrate where the nitride semiconductor layer is formed includes recesses having a maximum opening size of from 2 nm to 60 nm in an amount of from 1×109 pieces to 1×1011 pieces per cm2. The recesses and surfaces immediately above the recesses form spaces. Of a surface of the nitride semiconductor layer on the sapphire substrate side, a height difference ΔH between a surface immediately above of each recess and a surface in contact with a flat surface is 10 nm or less. A portion of the nitride semiconductor layer above each recess has a crystalline structure produced by growth along a polar plane of the group III element. ## Claims ### Claim 1 A nitride semiconductor substrate comprising: a sapphire substrate; and a nitride semiconductor layer formed on the sapphire substrate and containing a group III element including Al and nitrogen as a main component, wherein a surface of the sapphire substrate where the nitride semiconductor layer is formed includes recesses having a maximum opening size of from 2 nm to 60 nm in an amount of from 1×109 pieces to 1×1011 pieces per cm2, in which a space is formed by each of the recesses and a surface of the nitride semiconductor layer immediately above each recess; of a surface of the nitride semiconductor layer on the sapphire substrate side, a height difference between the surface immediately above the each recess and a surface in contact with a flat surface is 10 nm or less; and a portion of the nitride semiconductor layer above the each recess has a crystalline structure produced by growth along a polar plane of the group III element. ### Claim 2 (depends on 1) The nitride semiconductor substrate according to claim 1, wherein the surface of the sapphire substrate where the nitride semiconductor layer is formed includes the recesses having a maximum opening size of from 2 nm to 60 nm in an amount of from 3×109 pieces to 1×1011 pieces per cm2. ### Claim 3 (depends on 1) The nitride semiconductor substrate according to claim 1, wherein a crystallinity of the nitride semiconductor layer is from 45 arcsec to 70 arcsec on (0002) plane, and is from 240 arcsec to 290 arcsec on (10-12) plane. ### Claim 4 (depends on 1) The nitride semiconductor substrate according to claim 1, wherein a surface of the nitride semiconductor layer on a side opposite to the sapphire substrate has a root mean square roughness (Rq) of from 0.15 nm to 1 nm. ### Claim 5 (depends on 1) The nitride semiconductor substrate according to claim 1, wherein portions of the nitride semiconductor layer on the flat surface have a crystalline structure produced by growth along the polar plane of the group III element. ### Claim 6 (depends on 1) The nitride semiconductor substrate according to claim 1, wherein a depth of the recesses is from 5 nm to 50 nm. ### Claim 7 (depends on 1) The nitride semiconductor substrate according to claim 1, wherein a maximum size of bottom surfaces of the recesses is equal to or less than 1/10 of the maximum opening size of the recesses. ### Claim 8 (depends on 1) An ultraviolet light emitting element comprising a nitride semiconductor substrate that is the nitride semiconductor substrate according to claim 1, in which the nitride semiconductor layer contains AlN as the main component; and a nitride semiconductor laminated portion formed on the nitride semiconductor layer, the nitride semiconductor laminated portion including an n-type nitride semiconductor layer, a light emitting layer, and a p-type nitride semiconductor layer in this order from the nitride semiconductor layer side. ### Claim 9 (depends on 8) An ultraviolet light emitting device comprising the ultraviolet light emitting element according to claim 8. ### Claim 10 (depends on 1) An ultraviolet light receiving element comprising: a nitride semiconductor substrate that is the nitride semiconductor substrate according to claim 1, in which the nitride semiconductor layer contains AlN as the main component; a first nitride semiconductor layer formed on the nitride semiconductor layer and including Al and Ga; a second nitride semiconductor layer formed on the first nitride semiconductor layer and including Al and Ga, in which second nitride semiconductor layer has an Al content higher than the Al content of the first nitride semiconductor layer; and an electrode pair formed on the second nitride semiconductor layer. ### Claim 11 (depends on 10) An ultraviolet light receiving device comprising the ultraviolet light receiving element according to claim 10. ### Claim 12 A method for manufacturing a nitride semiconductor substrate comprising: a first step of forming, on a sapphire substrate, a recess forming film having a thickness of from 0.1 nm to 10 nm and containing, as a main component, a nitride semiconductor including a group III element including Al and nitrogen; a second step of forming through holes in the recess forming film by annealing the sapphire substrate after the first step at a temperature of from 1100° C. to 1350° C. to form recesses having a maximum opening size of from 2 nm to 60 nm in an amount of from 3×109 pieces to 1×1011 pieces per cm2 on a surface of the sapphire substrate where the recess forming film is formed; and a third step of forming a nitride semiconductor layer containing a group III element including Al and nitrogen as a main component on the recess forming film of the sapphire substrate after the second step. ### Claim 13 (depends on 2) The nitride semiconductor substrate according to claim 2, wherein a crystallinity of the nitride semiconductor layer is from 45 arcsec to 70 arcsec on (0002) plane, and is from 240 arcsec to 290 arcsec on (10-12) plane. ### Claim 14 (depends on 3) The nitride semiconductor substrate according to claim 3, wherein a crystallinity of the nitride semiconductor layer is from 45 arcsec to 70 arcsec on (0002) plane, and is from 240 arcsec to 290 arcsec on (10-12) plane. ### Claim 15 (depends on 2) The nitride semiconductor substrate according to claim 2, wherein portions of the nitride semiconductor layer on the flat surface have a crystalline structure produced by growth along the polar plane of the group III element. ### Claim 16 (depends on 2) The nitride semiconductor substrate according to claim 2, wherein a depth of the recesses is from 5 nm to 50 nm. ### Claim 17 (depends on 2) The nitride semiconductor substrate according to claim 2, wherein a maximum size of bottom surfaces of the recesses is equal to or less than 1/10 of the maximum opening size of the recesses. ### Claim 18 (depends on 5) The nitride semiconductor substrate according to claim 5, wherein a depth of the recesses is from 5 nm to 50 nm. ### Claim 19 (depends on 5) The nitride semiconductor substrate according to claim 5, wherein a maximum size of bottom surfaces of the recesses is equal to or less than 1/10 of the maximum opening size of the recesses. ### Claim 20 (depends on 6) The nitride semiconductor substrate according to claim 6, wherein a maximum size of bottom surfaces of the recesses is equal to or less than 1/10 of the maximum opening size of the recesses.