# US 7,611,639 B2 · Glass substrate for information recording medium 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 7,611,639 B2 - Document ID: US7611639B2 - Status: Granted - Kind: B2 - Application number: 10/532,538 - Filed: 2003-10-22 - Published: 2006-01-05 - Granted: 2009-11-03 - Earliest claimed: 2002-10-23 - Assignees: Hoya Corporation - Inventors: Yasuhiro Saito; Toshiaki Hashimoto; Yuriko Kudoh - Web page: https://patentgrep.com/patent/US7611639B2 ## 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) - C03C 17/001: {General methods for coating; Devices therefor} - G11B 5/8404: {manufacturing base layers} - C03C 2218/328: Partly or completely removing a coating - 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 - G11B: INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER (recording measured values in a way that does not require playback through a transducer G01D9/00; recording or playback apparatus using mechanically marked tape, e.g. punched paper tape, or using unit records, e.g. punched or magnetically marked cards G06K; transferring data from one type of record carrier to another G06K1/18; circuits for coupling output of reproducer to radio receiver H04B1/20; gramophone pick-ups or like acoustic electromechanical transducers or circuits therefor H04R) ## Abstract A method for manufacturing a glass substrate having projections of the same height. The method includes forming a surface layer having a decreased chemical resistance on a glass plate, forming a texture including a plurality of projections having upper portions included in the surface layer, and selectively removing the surface layer. ## Claims ### Claim 1 A method for manufacturing a glass substrate for an information recording medium, the manufacturing method comprising: forming a surface layer on a surface of a disk-shaped glass plate having a predetermined composition and a predetermined chemical resistance, with the surface layer having a composition differing from the predetermined composition and a chemical resistance that is lower than the predetermined chemical resistance; scrubbing the surface in a circumferential direction with an abrasive and a scrub member to form a texture including a plurality of projections each extending in a circumferential direction of the surface, the scrubbing forming the projections extending over the surface layer and a lower layer adjacent to the surface layer by removing the surface layer and the lower layer; and thereafter selectively removing an upper portion of the projections included in the surface layer with an etching liquid, wherein a ratio of a maximum peak height, Rp, to an arithmetic mean roughness, Ra, of the surface layer is 8 or less. ### Claim 2 (depends on 1) The manufacturing method according to claim 1, wherein the etching liquid is alkaline. ### Claim 3 (depends on 1) The manufacturing method according to claim 1, wherein the glass plate is a multi-component glass material containing at least silicon oxide, and said forming a surface layer includes decreasing the ingredient ratio of at least one component excluding silicon oxide so that the ingredient ratio of silicon oxide in the surface layer is greater than that in a portion excluding the surface layer. ### Claim 4 (depends on 3) The manufacturing method according to claim 3, wherein the multi-component glass material contains at least one of aluminum oxide and alkaline earth metal oxide, and the at least one component is the at least one of aluminum oxide and alkaline earth metal oxide. ### Claim 5 (depends on 1) The manufacturing method according to claim 1, wherein the surface layer has a thickness of 1 to 7 nm. ### Claim 6 (depends on 1) The manufacturing method according to claim 1, wherein said forming a surface layer includes immersing the glass plate in a strong acid solution having a pH of 3.0 or less and then immersing the glass plate in a strong alkaline solution having a pH of 10.5 or greater. ### Claim 7 (depends on 1) The manufacturing method according to claim 1, wherein said forming a texture includes scrubbing the surface so that the projections reach a lower layer of the surface layer. ### Claim 8 (depends on 4) The manufacturing method according to claim 4, wherein said forming a surface layer includes an acid process, for immersing the glass plate in a strong acid solution and dissolving the at least one of aluminum oxide and alkaline earth metal oxide in the strong acid solution to form the surface layer, and an alkaline process, for subsequently immersing the glass plate in a strong alkaline solution, the alkaline process uniformly etching the surface layer to adjust the thickness and adjust the composition of the surface layer. ### Claim 9 (depends on 3) The manufacturing method according to claim 3, wherein the ingredient ratio of silicon oxide in the surface layer is greater than 1.0 time but less than or equal to 1.4 times the ingredient ratio of silicon oxide in the portion excluding the surface layer. ### Claim 10 A method for manufacturing a glass substrate for an information recording medium, the manufacturing method comprising: preparing a disk-shaped glass plate having a predetermined composition and a predetermined chemical resistance; polishing the glass plate to form a smooth surface; chemically processing the smooth surface to form a surface layer having a composition differing from the predetermined composition, a chemical resistance that is lower than the predetermined chemical resistance, and a first thickness; forming a texture in a circumferential direction, the texture including a plurality of projections on the surface, each of the projections extending in a circumferential direction, wherein the projections extending over the surface layer and a lower layer adjacent to the surface layer are formed by removing the surface layer and the lower layer; and thereafter selectively removing only part of the plurality of projections included in the surface layer so that the plurality of projections have flat upper surfaces that are flush with each other, wherein a ratio of a maximum peak height, Rp, to an arithmetic mean roughness, Ra, of the surface layer is 8 or less. ### Claim 11 (depends on 10) The manufacturing method according to claim 10, wherein said forming a surface layer includes scrubbing the surface with a scrub member in a circumferential direction of the glass plate. ### Claim 12 (depends on 10) The manufacturing method according to claim 10, wherein said removing includes uniformly etching the surface layer so that the surface layer remaining on the lower layer has a second thickness that is less than the first thickness.