# US 2010/0167187 A1 · Reflective-type mask blank for euv lithography > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2010/0167187 A1 - Document ID: US20100167187A1 - Status: Published application - Kind: A1 - Application number: 12/694,860 - Filed: 2010-01-27 - Published: 2010-07-01 - Earliest claimed: 2006-01-12 - Assignees: Asahi Glass Company, Limited - Inventors: Yoshiaki IKUTA; Toshiyuki Uno; Ken Ebihara - Web page: https://patentgrep.com/patent/US20100167187A1 ## CPC - G03F 1/24: Reflection masks; Preparation thereof - B82Y 10/00: Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic - B82Y 40/00: Manufacture or treatment of nanostructures - G03F 1/38: Masks having auxiliary features, e.g. special coatings or marks for alignment or testing; Preparation thereof - G03F 1/40: Electrostatic discharge [ESD] related features, e.g. antistatic coatings or a conductive metal layer around the periphery of the mask substrate - G03F 7/70708: {being electrostatic; Electrostatically deformable vacuum chucks} - G21K 2201/067: Construction details - Y10T 428/31616: Next to polyester [e.g., alkyd] - 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) - B82Y: SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES - G21K: HANDLING OF PARTICLES OR IONISING RADIATION NOT OTHERWISE PROVIDED FOR; IRRADIATION DEVICES; GAMMA RAY OR X-RAY MICROSCOPES - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract A reflective mask blank for EUV lithography including a substrate having a front surface and a rear surface, a reflective layer formed over the front surface of the substrate, an absorbing layer formed over the reflective layer, and a chucking layer formed on the rear surface of the substrate and positioned to chuck the substrate to an electrostatic chuck. The substrate has a non-conducting portion which eliminates electrical conduction between the reflective layer and the chucking layer and electrical conduction between the absorbing layer and the chucking layer, and the non-conducting portion is formed by forming a portion of the substrate covered with one or more covering members and preventing formation of the reflective layer and the absorbing layer. ## Claims ### Claim 1 A reflective mask blank for EUV lithography, comprising: a substrate having a front surface and a rear surface; a reflective layer formed over the front surface of the substrate; an absorbing layer formed over the reflective layer; and a chucking layer formed on the rear surface of the substrate and positioned to chuck the substrate to an electrostatic chuck, wherein the substrate has a non-conducting portion which eliminates electrical conduction between the reflective layer and the chucking layer and electrical conduction between the absorbing layer and the chucking layer, and the non-conducting portion is formed by forming a portion of the substrate covered with at least one covering member and preventing formation of the reflective layer and the absorbing layer. ### Claim 2 (depends on 1) The reflective mask blank according to claim 1, wherein the resistance value between the reflective layer and the chucking layer and the resistance value between the absorbing layer and the chucking layer are 1 MΩ or above. ### Claim 3 (depends on 1) The reflective mask blank according to claim 1, wherein the non-conducting portion is formed on the rear surface and positioned in a region beginning from edges of the substrate and extending in a width of 2 mm or above measured from the edges. ### Claim 4 (depends on 1) The reflective mask blank according to claim 1, wherein the chucking layer is formed in a region which has a smaller area than a contact area of the electrostatic chuck with the substrate, when the substrate is supported by the electrostatic chuck. ### Claim 5 (depends on 1) The reflective mask blank according to claim 1, wherein the non-conducting portion is formed on the front surface of the substrate. ### Claim 6 (depends on 5) The reflective mask blank according to claim 5, wherein the non-conducting portion is formed from edges of the substrate and extends in a width of 1 mm or above measured from the edges. ### Claim 7 (depends on 1) The reflective mask blank according to claim 1, wherein the reflective layer and the absorbing layer are formed in a square shape. ### Claim 8 (depends on 1) The reflective mask blank according to claim 1, wherein the non-conducting portion is formed on a lateral surface of the substrate. ### Claim 9 (depends on 1) A reflective mask for EUV lithography, fabricated by patterning the reflective mask blank defined in claim 1. ### Claim 10 (depends on 1) The reflective mask blank according to claim 1, wherein the substrate comprises SiO2—TiO2 glass, and the SiO2—TiO2 glass has one of a hydrogen molecule content of less than 5×1017 molecules/cm3 and an OH group content of 600 wt.ppm or below. ### Claim 11 (depends on 1) The reflective mask blank according to claim 1, further comprising a low-reflective layer on the absorbing layer, wherein the non-conductive portion eliminates electrical conduction between the low-reflective layer and the chucking layer. ### Claim 12 (depends on 1) The reflective mask blank according to claim 1, wherein the reflective layer is formed by depositing Si films and Mo films in from 30 to 50 cycles, and the reflective layer has a total thickness of from 200 to 400 nm. ### Claim 13 (depends on 1) The reflective mask blank according to claim 1, wherein the reflective layer has a capping layer formed as a top layer thereof. ### Claim 14 (depends on 1) The reflective mask blank according to claim 1, wherein the chucking layer comprises at least one metal material selected from the group consisting of Cr, Ni, Ti, Ta, Mo, Si and W. ### Claim 15 (depends on 1) The reflective mask blank according to claim 1, wherein the absorbing layer comprises Cr, Ta or a nitride thereof. ### Claim 16 (depends on 1) The reflective mask blank according to claim 1, further comprising an intermediate layer interposed between the reflective layer and the absorbing layer, wherein the non-conductive portion eliminates electrical conduction between the intermediate layer and the chucking layer. ### Claim 17 (depends on 1) The reflective mask blank according to claim 1, wherein the reflective layer includes a capping layer which prevents a surface of the reflective layer from being oxidized. ### Claim 18 A method for manufacturing a reflective mask blank for EUV lithography, comprising: providing a substrate having a front surface and a rear surface; covering a portion of the substrate with a first covering member which prevents formation of a reflective layer; forming a reflective layer over the front surface of the substrate such that the portion covered with the first covering member forms a non-conducting portion which eliminates electrical conduction between the reflective layer and a chucking layer; forming an absorbing layer over the reflective layer such that the non-conducting portion eliminates electrical conduction between the absorbing layer and the chucking layer by forming the portion covered with at least one of the first covering member and a second covering member and preventing formation of the absorbing layer; and forming the chucking layer on the rear surface of the substrate such that the chucking layer is positioned to chuck the substrate to an electrostatic chuck. ### Claim 19 (depends on 18) The method for manufacturing a reflective mask blank for EUV lithography according to claim 18, wherein the forming of the reflective layer comprises forming a reflective layer including a capping layer which prevents a surface of the reflective layer from being oxidized. ### Claim 20 (depends on 18) The method for manufacturing a reflective mask blank for EUV lithography according to claim 18, further comprising forming an intermediate layer on the reflective layer, wherein the non-conductive portion eliminates electrical conduction between the intermediate layer and the chucking layer. ### Claim 21 (depends on 18) The method for manufacturing a reflective mask blank for EUV lithography according to claim 18, further comprising forming a low-reflective layer on the absorbing layer, wherein the non-conductive portion eliminates electrical conduction between the low-reflective layer and the chucking layer. ### Claim 22 (depends on 18) The method for manufacturing a reflective mask blank for EUV lithography according to claim 18, wherein the forming of the chucking layer is carried out after the forming of the reflective layer. ### Claim 23 (depends on 18) The method for manufacturing a reflective mask blank for EUV lithography according to claim 18, wherein the covering comprises covering the portion of the substrate with the first covering member comprising one of a photosensitive resist and a polyimide tape. ### Claim 24 (depends on 18) The method for manufacturing a reflective mask blank for EUV lithography according to claim 18, wherein the forming of the chucking layer is carried out before the forming of the reflective layer.