# US 8,772,054 B2 · Focus control method for photolithography > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,772,054 B2 - Document ID: US8772054B2 - Status: Granted - Kind: B2 - Application number: 13/227,805 - Filed: 2011-09-08 - Published: 2013-03-14 - Granted: 2014-07-08 - Earliest claimed: 2011-09-08 - Assignees: Taiwan Semiconductor Manufacturing Company, Ltd. - Applicants: Jen-Pan Wang; Chien-Hsuan Liu; Ching-Hsien Chen; Chao-Chi Chen - Inventors: Jen-Pan Wang; Chien-Hsuan Liu; Ching-Hsien Chen; Chao-Chi Chen - Web page: https://patentgrep.com/patent/US8772054B2 ## CPC - G03F 7/70641: {Focus} - 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 9/7026: {Focusing} - G03F 9/7034: {Leveling} - G03F 9/7053: {Non-optical, e.g. mechanical, capacitive, using an electron beam, acoustic or thermal waves} - 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 method comprises providing a semiconductor substrate having at least one layer of a material over the substrate. A sound is applied to the substrate, such that a sound wave is reflected by a top surface of the layer of material The sound wave is detected using a sensor. A topography of the top surface is determined based on the detected sound wave. The determined topography is used to control an immersion lithography process. ## Claims ### Claim 1 A method comprising: (a) providing a semiconductor substrate having at least one layer of a material over the substrate; (b) applying sound to the substrate, such that a sound wave is reflected by a top surface of the layer of material; (c) detecting the sound wave using a sensor; (d) determining a topography of the top surface based on the detected sound wave; and (e) using the determined topography to control an immersion lithography process. ### Claim 2 (depends on 1) The method of claim 1, wherein the material is a photoresist, and step (e) comprises: adjusting a focus of an immersion photolithography tool based on the determined topography; and exposing the photoresist after adjusting the focus. ### Claim 3 (depends on 2) The method of claim 2, wherein the topography is determined with sufficient precision to measure intra-field variations in surface height, and the adjusting step is performed individually for scanning each respective field of the substrate. ### Claim 4 (depends on 2) The method of claim 2, further comprising: before exposing the photoresist, adjusting an energy level of a beam of the immersion photolithography tool based on the determined topography. ### Claim 5 (depends on 4) The method of claim 4, wherein at least one of the focus and energy level of the beam is adjusted individually at each of a plurality of locations within each field for exposing each respective field of the substrate. ### Claim 6 (depends on 2) The method of claim 2, wherein the determining step is performed in situ in the immersion photolithography tool. ### Claim 7 (depends on 6) The method of claim 6, wherein the immersion photolithography tool has a lens that provides light during the exposing, the method further comprising: flowing liquid through a space between the top surface of the photoresist and the lens. ### Claim 8 (depends on 7) The method of claim 7, wherein the liquid is water. ### Claim 9 (depends on 2) The method of claim 2, wherein the substrate has an inter-metal dielectric layer below the layer of photoresist, and the inter-metal dielectric layer has a plurality of copper patterns. ### Claim 10 (depends on 2) The method of claim 2, wherein steps (b), (c), (d), and (e) are performed in situ in a chamber without removing the substrate from the chamber. ### Claim 11 A method comprising: (a) providing a semiconductor substrate having an inter-metal dielectric layer with a plurality of metal patterns, and a layer of photoresist over the inter-metal dielectric layer; (b) applying sound to the substrate, such that a sound wave is reflected by a top surface of the layer of photoresist; (c) using a sensor to detect the sound wave; and (d) determining a topography of the top surface based on the detected sound wave, with sufficient precision to measure intra-field variations in surface height; (e) adjusting a focus of a photolithography tool and an energy level of a beam of the photolithography tool, based on the determined topography; and (f) exposing the photoresist after adjusting the focus and energy level. ### Claim 12 (depends on 11) The method of claim 11, wherein the exposing comprises an immersion exposure process, and the determining step is performed in situ in the photolithography tool. ### Claim 13 (depends on 12) The method of claim 12, wherein the photolithography tool has a lens that provides light during the immersion exposure process, the method further comprising: flowing water through a space between the top surface of the photoresist and the lens. ### Claim 14 (depends on 11) The method of claim 11, wherein the focus and energy level of the beam are adjusted individually for exposing each respective field of the substrate. ### Claim 15 (depends on 11) The method of claim 11, wherein steps (b), (c), (d), (e) ad (f) are performed in situ in a chamber without removing the substrate from the chamber.