# US 2020/0399504 A1 · Polishing agent for synthetic quartz glass substrate and method for polishing synthetic quartz glass substrate > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2020/0399504 A1 - Document ID: US20200399504A1 - Status: Published application - Kind: A1 - Application number: 16/765,040 - Filed: 2018-10-18 - Published: 2020-12-24 - Earliest claimed: 2017-11-17 - Assignees: Shin-Etsu Chemical Co., Ltd. - Applicants: Shin-Etsu Chemical Co., Ltd. - Inventors: Mitsuhito TAKAHASHI - Web page: https://patentgrep.com/patent/US20200399504A1 ## CPC - C09G 1/02: containing abrasives or grinding agents {(abrasives as such C09K3/14; polishing of semi-conductors H10P52/40)} - B24B 37/00: Lapping machines or devices; Accessories (B24B3/00 takes precedence) - B24B 37/044: {characterised by the composition of the lapping agent} - C03C 19/00: Surface treatment of glass, not in the form of fibres or filaments, by mechanical means (sand-blasting, grinding, or polishing glass B24) - C09K 3/1409: {Abrasive particles per se (preparation of diamond C01B32/25)} - C09K 3/1454: {Abrasive powders, suspensions and pastes for polishing} - C09K 3/1463: {Aqueous liquid suspensions} - C09G: POLISHING COMPOSITIONS (French polish C09F11/00); SKI WAXES - B24B: MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING (grinding of gear teeth B23F, of screw-threads B23G1/36; by electro-erosion B23H; abrasive or related blasting B24C; tools for grinding, buffing or sharpening B24D; polishing compositions C09G1/00; abrasives C09K3/14; electrolytic etching or polishing C25F3/00; grinding arrangements for use on assembled railway tracks E01B31/17); DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS - C03C: CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS - C09K: MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE ## Abstract A polishing agent for a synthetic quartz glass substrate. The polishing agent contains wet ceria particles and non-spherical silica particles. The wet ceria particles have an average primary particle diameter of 30 nm to 50 nm. The non-spherical silica particles have an average primary particle diameter of 80 nm to 120 nm. This provides a polishing agent for a synthetic quartz glass substrate, the polishing agent having high polishing rate and being capable of sufficiently reducing generation of defects due to polishing. ## Claims ### Claim at position 1 1-5. (canceled) ### Claim 6 A polishing agent for a synthetic quartz glass substrate, the polishing agent comprising: wet ceria particles; and non-spherical silica particles, wherein the wet ceria particles have an average primary particle diameter of 30 nm to 50 nm, and the non-spherical silica particles have an average primary particle diameter of 80 nm to 120 nm. ### Claim 7 (depends on 6) The polishing agent for a synthetic quartz glass substrate according to claim 6, wherein the wet ceria particles have a degree of association of 1.0 to 3.0, and the non-spherical silica particles are associated silica particles and have a degree of association of 2.0 to 3.5. ### Claim 8 (depends on 6) The polishing agent for a synthetic quartz glass substrate according to claim 6, wherein a content of the wet ceria particles in the polishing agent is 1.5 times to 3.0 times as high as a content of the non-spherical silica particles in a mass ratio. ### Claim 9 (depends on 7) The polishing agent for a synthetic quartz glass substrate according to claim 7, wherein a content of the wet ceria particles in the polishing agent is 1.5 times to 3.0 times as high as a content of the non-spherical silica particles in a mass ratio. ### Claim 10 (depends on 6) The polishing agent for a synthetic quartz glass substrate according to claim 6, wherein a total content of the wet ceria particles and the non-spherical silica particles in the polishing agent is 20 parts by mass to 50 parts by mass per 100 parts by mass of the polishing agent. ### Claim 11 (depends on 7) The polishing agent for a synthetic quartz glass substrate according to claim 7, wherein a total content of the wet ceria particles and the non-spherical silica particles in the polishing agent is 20 parts by mass to 50 parts by mass per 100 parts by mass of the polishing agent. ### Claim 12 (depends on 8) The polishing agent for a synthetic quartz glass substrate according to claim 8, wherein a total content of the wet ceria particles and the non-spherical silica particles in the polishing agent is 20 parts by mass to 50 parts by mass per 100 parts by mass of the polishing agent. ### Claim 13 (depends on 9) The polishing agent for a synthetic quartz glass substrate according to claim 9, wherein a total content of the wet ceria particles and the non-spherical silica particles in the polishing agent is 20 parts by mass to 50 parts by mass per 100 parts by mass of the polishing agent. ### Claim 14 (depends on 6) A method for polishing a synthetic quartz glass substrate, comprising a rough polishing step and a final polishing step after the rough polishing step, wherein the polishing agent for a synthetic quartz glass substrate according to claim 6 is used in the final polishing step for final polishing. ### Claim 15 (depends on 7) A method for polishing a synthetic quartz glass substrate, comprising a rough polishing step and a final polishing step after the rough polishing step, wherein the polishing agent for a synthetic quartz glass substrate according to claim 7 is used in the final polishing step for final polishing. ### Claim 16 (depends on 8) A method for polishing a synthetic quartz glass substrate, comprising a rough polishing step and a final polishing step after the rough polishing step, wherein the polishing agent for a synthetic quartz glass substrate according to claim 8 is used in the final polishing step for final polishing. ### Claim 17 (depends on 9) A method for polishing a synthetic quartz glass substrate, comprising a rough polishing step and a final polishing step after the rough polishing step, wherein the polishing agent for a synthetic quartz glass substrate according to claim 9 is used in the final polishing step for final polishing. ### Claim 18 (depends on 10) A method for polishing a synthetic quartz glass substrate, comprising a rough polishing step and a final polishing step after the rough polishing step, wherein the polishing agent for a synthetic quartz glass substrate according to claim 10 is used in the final polishing step for final polishing. ### Claim 19 (depends on 11) A method for polishing a synthetic quartz glass substrate, comprising a rough polishing step and a final polishing step after the rough polishing step, wherein the polishing agent for a synthetic quartz glass substrate according to claim 11 is used in the final polishing step for final polishing. ### Claim 20 (depends on 12) A method for polishing a synthetic quartz glass substrate, comprising a rough polishing step and a final polishing step after the rough polishing step, wherein the polishing agent for a synthetic quartz glass substrate according to claim 12 is used in the final polishing step for final polishing. ### Claim 21 (depends on 13) A method for polishing a synthetic quartz glass substrate, comprising a rough polishing step and a final polishing step after the rough polishing step, wherein the polishing agent for a synthetic quartz glass substrate according to claim 13 is used in the final polishing step for final polishing.