# US 10,871,715 B2 · Lithographic apparatus and a device manufacturing method > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,871,715 B2 - Document ID: US10871715B2 - Status: Granted - Kind: B2 - Application number: 16/690,198 - Filed: 2019-11-21 - Published: 2020-06-11 - Granted: 2020-12-22 - Earliest claimed: 2018-12-06 - Assignees: ASML Netherlands B.V. - Applicants: Asml Netherlands B.V. - Inventors: Thomas Poiesz; Bert Dirk Scholten; Dirk Willem Harberts; Lucas Henricus Johannes Stevens; Laura Maria Fernandez Diaz; Johannes Adrianus Cornelis Maria Pijnenburg; Abraham Alexander Soethoudt; Wilhelmus Jacobus Johannes Welters; Jimmy Matheus Wilhelmus Van De Winkel - Web page: https://patentgrep.com/patent/US10871715B2 ## CPC - G03F 7/70341: {Details of immersion lithography aspects, e.g. exposure media or control of immersion liquid supply (chemical composition of immersion liquids G03F7/2041)} - G03F 7/707: {Chucks, e.g. chucking or un-chucking operations or structural details} - 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 substrate table for an immersion system having a projection system arranged to project an image onto a substrate and a liquid confinement system configured to confine an immersion liquid to a space between the projection system and the substrate, the substrate table including: a substrate holder configured to hold a substrate; and a current control device arranged to reduce an electric current flowing between the substrate and the substrate holder while the immersion liquid is confined to the space. ## Claims ### Claim 1 A substrate table for an immersion system comprising a projection system arranged to project an image onto a substrate and a liquid confinement system configured to confine an immersion liquid to a space between the projection system and the substrate, the substrate table comprising: a substrate holder configured to hold the substrate; and a current control device arranged to reduce an electric current flowing between the substrate and the substrate holder while the immersion liquid is confined to the space. ### Claim 2 (depends on 1) The substrate table according to claim 1, wherein the current control device provides an impedance of greater than 100 kΩ between the substrate holder and ground. ### Claim 3 (depends on 1) The substrate table according to claim 1, wherein the current control device provides an impedance of greater than 1 MΩ between the substrate holder and ground. ### Claim 4 (depends on 2) The substrate table according to claim 2, wherein the impedance is variable and the current control device further comprises a controller to control the impedance. ### Claim 5 (depends on 1) The substrate table according to claim 1, wherein the current control device further comprises: a current detector to detect a current between the substrate holder and ground; and a controller to control an electrical power source and/or an impedance on the basis of the detection of current. ### Claim 6 (depends on 1) The substrate table according to claim 1, wherein the current control device further comprises: a voltage sensor to measure a potential of a part of the substrate and/or the substrate holder; and a controller to control an electrical power source and/or an impedance on the basis of the measured potential. ### Claim 7 (depends on 6) The substrate table according to claim 6, wherein the voltage sensor is arranged to measure a potential of a lower surface of the substrate, and the electrical power source is connected to the substrate holder or the substrate table. ### Claim 8 (depends on 6) The substrate table according to claim 6, wherein the voltage sensor is arranged to measure a potential of an upper surface of the substrate. ### Claim 9 (depends on 1) The substrate table according to claim 1, wherein the current control device comprises an electrical power source connected to the substrate holder and/or the substrate table. ### Claim 10 (depends on 1) The substrate table according to claim 1, further comprising an electrical heater configured to heat at least a part of the substrate and wherein the current control device comprises a grounded shield arranged between the electrical heater and the substrate holder. ### Claim 11 (depends on 1) The substrate table according to claim 1, wherein the current control device comprises a conductor configured to contact the substrate to provide a direct electrical path between the substrate and ground. ### Claim 12 (depends on 11) The substrate table according to claim 11, wherein the conductor comprises a burl having a hard conductive coating without an insulating outer layer. ### Claim 13 (depends on 12) The substrate table according to claim 12, wherein the hard conductive coating is made from at least one selected from: CrN, TiN, doped DLC, and/or an alloy containing one or more selected from: Ti, W and/or Mo. ### Claim 14 (depends on 11) The substrate table according to claim 11, wherein the conductor comprises an actuated pin configured to lift the substrate from the substrate holder. ### Claim 15 (depends on 1) A lithographic apparatus comprising: the substrate table of claim 1; a projection system arranged to project an image onto a substrate held by the substrate table; and a liquid confinement system configured to confine an immersion liquid to a space between the projection system and the substrate. ### Claim 16 A device manufacturing method comprising using a lithographic apparatus having a projection system to project an image onto a substrate held on a substrate holder, the method comprising: using a liquid confinement system to confine a liquid to a space between the projection system and the substrate; and reducing an electric current flowing between the substrate and the substrate holder while the immersion liquid is confined to the space. ### Claim 17 (depends on 16) The method according to claim 16, wherein the reducing the electric current comprises providing an impedance of greater than 100 kΩ between the substrate holder and ground and/or between the liquid confinement system and ground. ### Claim 18 (depends on 17) The method according to claim 17, comprising varying the impedance using a controller. ### Claim 19 (depends on 16) The method according to claim 16, wherein the reducing the electric current comprises: detecting a current between the substrate holder and ground; and controlling an electrical power source and/or an impedance on the basis of the detection of current. ### Claim 20 (depends on 16) The method according to claim 16, wherein the reducing the electric current comprises: measuring a potential of a part of the substrate and/or the substrate holder; and controlling an electrical power source and/or an impedance on the basis of the measured potential.