# US 2021/0243875 A1 · Light source for lithography exposure process > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2021/0243875 A1 - Document ID: US20210243875A1 - Status: Published application - Kind: A1 - Application number: 17/239,826 - Filed: 2021-04-26 - Published: 2021-08-05 - Earliest claimed: 2017-11-16 - Assignees: Taiwan Semiconductor Manufacturing Company, Ltd. - Applicants: Taiwan Semiconductor Manufacturing Company, Ltd. - Inventors: Chieh HSIEH; Shang-Chieh CHIEN; Chun-Chia HSU; Bo-Tsun LIU; Tzung-Chi FU; Li-Jui CHEN; Po-Chung CHENG - Web page: https://patentgrep.com/patent/US20210243875A1 ## CPC - H05G 2/0084: {Control of the laser beam} - G03F 7/70033: {by plasma extreme ultraviolet [EUV] sources} - H05G 2/0027: {Arrangements for controlling the supply; Arrangements for measurements} - H05G 2/0088: {for preconditioning the plasma generating material} - H05G: X-RAY TECHNIQUE (investigating or analysing materials by the use of X-rays G01N23/00; apparatus for X-ray photography G03B42/02; X-ray tubes H01J35/00; TV systems having X-ray input H04N5/321) - 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 for generating light is provided. The method further includes measuring a period of time during which one of targets from a fuel target generator passes through two detection positions. The method also includes exciting the targets with a laser generator so as to generate plasma that emits light. In addition, the operation of exciting the targets with the laser generator includes: irradiating a pre-pulse laser on the targets to expand the targets; detecting conditions of expanded targets; and adjusting at least one parameter of the laser generator according to the measured period of time and the conditions when the measured period of time is different from a predetermined value. The parameter of the laser generator which is adjusted according to the measured period of time includes a frequency for generating a laser for illuminating the targets. ## Claims ### Claim 1 A method for generating light in a lithography exposure process, comprising: measuring a period of time during which one of targets from a fuel target generator passes through two detection positions; exciting the targets with a laser generator so as to generate plasma that emits light, wherein the operation of exciting the targets with the laser generator comprises: irradiating a pre-pulse laser on the targets to expand the targets; detecting conditions of expanded targets; and adjusting at least one parameter of the laser generator according to the measured period of time and the conditions, when the measured period of time is different from a predetermined value, wherein the parameter of the laser generator which is adjusted according to the measured period of time comprises a frequency for generating a laser for illuminating the targets. ### Claim 2 (depends on 1) The method for generating light in a lithography exposure process as claimed in claim 1, wherein the operation of measuring the period of time comprises: projecting a first light curtain and a second light curtain at the two detection positions; receiving light reflected from one of the targets when the one of the targets passes through the two detection positions; and measuring a period of time between a time when the light reflected from the target at a first detection position is detected and a time when the light reflected from the target at as second detection position is detected. ### Claim 3 (depends on 1) The method for generating light in a lithography exposure process as claimed in claim 1, wherein the targets generated from the fuel target generator are separated by a droplet pitch, and a distance between the two detection positions is smaller than the droplet pitch. ### Claim 4 (depends on 1) The method for generating light in a lithography exposure process as claimed in claim 1, wherein the two detection positions are located between the fuel target generator and a lighting position where the targets are focused by the pre-pulse laser. ### Claim 5 (depends on 1) The method for generating light in a lithography exposure process as claimed in claim 1, wherein the pre-pulse laser irradiates the targets to expand the targets at a first lighting position, and the operation of exciting the targets to generate plasma further comprises: irradiating a main pulse laser on the expanded target to generate the plasma at a second lighting position; wherein the two detection positions are located between the first lighting position and the second lighting position. ### Claim 6 (depends on 1) The method for generating light in a lithography exposure process as claimed in claim 1, further comprising adjusting a parameter of the fuel target generator according to the measured period of time, wherein the parameter of the fuel target generator comprises a flow velocity of the targets generated from the fuel target generator. ### Claim 7 A method for generating light in a lithography exposure process, comprising: detecting a flow velocity of targets from a fuel target generator at a first detection position and a second detection position; adjusting the flow velocity of the targets in response to the detected flow velocity when the detected flow velocity is different from a predetermined value; and irradiating at least one laser on the targets with a laser generator to generate plasma that emits light; wherein the operation of irradiating the at least one laser on the targets comprises: irradiating a pre-pulse laser on the targets to expand the targets; detecting conditions of expanded targets; and adjusting a parameter of the laser generator according to the detected flow velocity and the conditions; wherein the operation of detecting the flow velocity of the targets comprises: projecting a first light curtain and a second light curtain at the first detection position and the second detection position, respectively, on a moving path; receiving light reflected from one of the targets when the one of the targets passes through the first detection position and the second detection position; measuring a time difference between a time when the light reflected from the target at the first detection position is detected and a time when the light reflected from the target at the second detection position is detected; and determining a flow velocity of the targets by dividing a distance between the first detection position and the second detection position by the measured time difference. ### Claim 8 (depends on 7) The method for generating light in a lithography exposure process as claimed in claim 7, wherein the parameter of the laser generator which is adjusted according to the measured time difference comprises a frequency for generating a laser for illuminating the targets. ### Claim 9 (depends on 7) The method for generating light in a lithography exposure process as claimed in claim 7, further comprising: calculating a time interval by dividing an intermediate distance by the detected velocity, wherein the intermediate distance is between the first detection position and a lighting position where the targets are illuminated by the laser; and wherein the laser is actuated after the time interval when the light reflected from the target at the first detection position is detected. ### Claim 10 (depends on 7) The method for generating light in a lithography exposure process as claimed in claim 7, wherein the operation of irradiating at least one laser on the targets comprises: irradiating a main pulse laser on the expanded target to generate plasma that emits light; wherein the velocity of the targets is detected before the targets are expanded by the pre-pulse laser. ### Claim 11 (depends on 7) The method for generating light in a lithography exposure process as claimed in claim 7, wherein the operation of irradiating at least one laser on the targets comprises: irradiating a main pulse laser on the expanded target to generate plasma that emits light; wherein the velocity of the targets is detected after the targets are expanded by the pre-pulse laser and before the expanded targets are irradiated by the main pulse laser. ### Claim 12 A method for generating light in a lithography exposure process, comprising: measuring a period of time during which one of targets from a fuel target generator passes through two detection positions; exciting the targets with a laser generator so as to generate plasma that emits light, wherein the operation of exciting the targets with a laser generator comprises: irradiating a pre-pulse laser on the targets to expand the targets; detecting length of expanded targets; and adjusting at least one parameter of the laser generator according to the measured period of time and the length of expanded targets, when the measured period of time is different from a predetermined value, wherein the parameter of the laser generator which is adjusted according to the measured period of time comprises a frequency for generating a laser for illuminating the targets. ### Claim 13 (depends on 12) The method for generating light in a lithography exposure process as claimed in claim 12, wherein the operation of measuring the period of time comprises: projecting a first light curtain and a second light curtain at the two detection positions; receiving light reflected from one of the targets when the one of the targets passes through the two detection positions; and measuring a period of time between a time when the light reflected from the target at a first detection position is detected and a time when the light reflected from the target at as second detection position is detected. ### Claim 14 (depends on 12) The method for generating light in a lithography exposure process as claimed in claim 12, wherein the targets generated from the fuel target generator are separated by a droplet pitch, and a distance between the two detection positions is smaller than the droplet pitch. ### Claim 15 (depends on 12) The method for generating light in a lithography exposure process as claimed in claim 12, wherein the two detection positions are located between the fuel target generator and a lighting position where the targets are focused by the pre-pulse laser. ### Claim 16 (depends on 12) The method for generating light in a lithography exposure process as claimed in claim 12, wherein the pre-pulse laser irradiates the targets to expand the targets at a first lighting position, and the operation of exciting the targets to generate plasma further comprises: irradiating a main pulse laser on the expanded target to generate the plasma at a second lighting position; wherein the two detection positions are located between the first lighting position and the second lighting position. ### Claim 17 (depends on 12) The method for generating light in a lithography exposure process as claimed in claim 12, further comprising adjusting a parameter of the fuel target generator according to the measured period of time, wherein the parameter of the fuel target generator comprises a flow velocity of the targets generated from the fuel target generator. ### Claim 18 (depends on 12) The method for generating light in a lithography exposure process as claimed in claim 12, wherein the laser generator comprises: a first laser source configured to generate the pre-pulse laser for expanding the targets at a first lighting position; wherein the two detection positions are located between the fuel target generator and the first lighting position. ### Claim 19 (depends on 12) The method for generating light in a lithography exposure process as claimed in claim 12, wherein the laser generator comprises: a first laser source configured to generate the pre-pulse laser for expanding the targets at a first lighting position; and a second laser source positioned farther away from the fuel target generator than the first laser source and configured to generate a main pulse laser for exciting the expanded targets at a second lighting position; wherein the two detection positions are located between the first lighting position and the second lighting position. ### Claim 20 (depends on 12) The method for generating light in a lithography exposure process as claimed in claim 12, wherein the period of time is measured by a monitoring device, and the length of expanded targets is detected by another monitoring device.