# US 10,865,139 B2 · Large-size synthetic quartz glass substrate, evaluation method, and manufacturing method > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,865,139 B2 - Document ID: US10865139B2 - Status: Granted - Kind: B2 - Application number: 15/972,416 - Filed: 2018-05-07 - Published: 2018-11-08 - Granted: 2020-12-15 - Earliest claimed: 2017-05-08 - Assignees: Shin-Etsu Chemical Co., Ltd. - Applicants: Shin-Etsu Chemical Co., Ltd. - Inventors: Yoko Ishitsuka; Atsushi Watabe; Daijitsu Harada; Masaki Takeuchi - Web page: https://patentgrep.com/patent/US10865139B2 ## CPC - 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) - B24B 1/00: Processes of grinding or polishing; Use of auxiliary equipment in connection with such processes - C03C 3/06: with more than 90% silica by weight, e.g. quartz {(C03C3/045 takes precedence)} - G01B 5/285: {for controlling eveness} - G03F 1/60: Substrates - C03C 2204/08: Glass having a rough surface - 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 - 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 - G01B: MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS - G03F: PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR; (phototypographic composing devices B41B; photosensitive materials or processes for photographic purposes G03C; electrophotography, sensitive layers or processes therefor G03G) ## Abstract A large-size synthetic quartz glass substrate has a diagonal length of at least 1,000 mm. Provided that an effective range is defined on the substrate surface, and the effective range is partitioned into a plurality of evaluation regions such that the evaluation regions partly overlap each other, a flatness in each evaluation region is up to 3 μm. From the quartz glass substrate having a high flatness and a minimal local gradient within the substrate surface, a large-size photomask is prepared. ## Claims ### Claim 1 A method for evaluating the flatness of a large-size synthetic quartz glass substrate having front and back surfaces, the method comprising the steps of: partitioning an effective range into a plurality of evaluation regions such that the evaluation regions partly overlap each other, the effective range defined on one or both of the front and back surfaces of the large-size synthetic quartz glass substrate; measuring a flatness within each evaluation region; and computing a difference between the flatness in one evaluation region and the flatness in another evaluation region overlapping the one evaluation region, wherein the large-size synthetic quartz glass substrate has a diagonal length of at least 1,000 mm, and a thickness of 5 to 30 mm. ### Claim 2 (depends on 1) The method of claim 1, wherein the substrate is rectangular, the effective range is a rectangular range defined on the substrate surface by removing a band extending 10 mm from each side of the substrate surface, the rectangular range having two pairs of opposed sides, and the evaluation region is delineated by one pair of opposed sides of the effective range and two straight lines parallel to the other pair of opposed sides and has a width of 100 to 300 mm along the one pair of opposed sides. ### Claim 3 (depends on 1) The method of claim 1, wherein for each evaluation region, the area of the overlap between that evaluation region and the closest one of overlapping evaluation regions is 50 to 98% of the area of each evaluation region. ### Claim 4 (depends on 1) A method for manufacturing a large-size synthetic quartz glass substrate, comprising the steps of: evaluating the flatness of a large-size quartz glass substrate according to the method of claim 1, determining an amount of material removal in polishing on the basis of the measured flatness and flatness difference, and locally polishing the surface of the quartz glass substrate in accordance with the determined amount of material removal in polishing. ### Claim 5 (depends on 4) The method of claim 4, wherein the substrate is rectangular, the effective range is a rectangular range defined on the substrate surface by removing a band extending 10 mm from each side of the substrate surface, the rectangular range having two pairs of opposed sides, and the evaluation region is delineated by one pair of opposed sides of the effective range and two straight lines parallel to the other pair of opposed sides and has a width of 100 to 300 mm along the one pair of opposed sides. ### Claim 6 (depends on 4) The method of claim 4, wherein for each evaluation region, the area of the overlap between that evaluation region and the closest one of overlapping evaluation regions is 50 to 98% of the area of each evaluation region. ### Claim 7 (depends on 4) The method of claim 4, wherein the surface of the quartz glass substrate is locally polished in accordance with the determined amount of material removal in polishing so that a flatness in each evaluation region is up to 3 μm.