# US 10,871,722 B2 · Photomask purging system and method > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,871,722 B2 - Document ID: US10871722B2 - Status: Granted - Kind: B2 - Application number: 16/200,291 - Filed: 2018-11-26 - Published: 2020-01-16 - Granted: 2020-12-22 - Earliest claimed: 2018-07-16 - Assignees: Taiwan Semiconductor Manufacturing Company, Ltd. - Applicants: Taiwan Semiconductor Manufacturing Co., Ltd. - Inventors: Chung-Yi Yen; Mei-Tsu Lai; Chen-Hung Lin; Chien-Chou Ke; You-Cheng Yeh; Tai-Hsiang Lin - Web page: https://patentgrep.com/patent/US10871722B2 ## CPC - G03F 7/70741: {Handling masks outside exposure position, e.g. reticle libraries} - G03F 7/70933: {Purge, e.g. exchanging fluid or gas to remove pollutants} - G03F 1/82: Auxiliary processes, e.g. cleaning or inspecting - G03F 7/70925: {Cleaning, i.e. actively freeing apparatus from pollutants, e.g. using plasma cleaning} - G03F 7/70983: {Optical system protection, e.g. pellicles or removable covers for protection of mask} - 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 photomask purging method includes opening a pod having a photomask therein, gripping the photomask by an end effector, moving the end effector from the opened pod to a destination where a gas exit is toward, exhausting a gas from the gas exit toward the gripped photomask, and rotating the end effector with respect to a horizontal plane when the end effector is at the destination where the gas exit is toward. ## Claims ### Claim 1 A photomask purging method, comprising: opening a pod having a photomask therein; gripping the photomask by an end effector; moving the end effector from the opened pod to a destination where a gas exit is toward; exhausting a gas from the gas exit toward the gripped photomask; rotating the end effector with respect to a horizontal plane when the end effector is at the destination where the gas exit is toward; and rotating the gas exit with respect to the horizontal plane before exhausting the gas from the gas exit is stopped. ### Claim 2 (depends on 1) The photomask purging method of claim 1, wherein rotating the end effector is performed during exhausting the gas. ### Claim 3 (depends on 1) The photomask purging method of claim 1, wherein exhausting the gas comprises: providing the gas from a gas source to the gas exit through a gas line; switching an on/off valve in the gas line at a switch frequency; and varying the switch frequency of the on/off valve. ### Claim 4 (depends on 3) The photomask purging method of claim 3, wherein varying the switch frequency of the on/off valve is performed such that the switch frequency of the on/off valve is varied in an oscillating manner. ### Claim 5 (depends on 3) The photomask purging method of claim 3, wherein varying the switch frequency of the on/off valve is performed such that the switch frequency of the on/off valve has a substantially sine waveform. ### Claim 6 (depends on 1) The photomask purging method of claim 1, further comprising: varying a flow rate of the gas exhausted from the gas exit. ### Claim 7 (depends on 6) The photomask purging method of claim 6, wherein varying the flow rate of the gas is performed such that the flow rate of the gas is varied in an oscillating manner. ### Claim 8 (depends on 6) The photomask purging method of claim 6, wherein varying the flow rate of the gas is performed such that the flow rate of the gas has a substantially sine waveform. ### Claim 9 (depends on 1) The photomask purging method of claim 1, wherein opening the pod comprises automatedly opening the pod. ### Claim 10 (depends on 1) The photomask purging method of claim 1, further comprising: automatedly inspecting the photomask prior to opening the pod. ### Claim 11 (depends on 10) The photomask purging method of claim 10, wherein automatedly inspecting the photomask is performed in a lithographic tool. ### Claim 12 (depends on 1) The photomask purging method of claim 1, wherein the end effector is rotated such that the gripped photomask is tilted with respect to the horizontal plane, and the gas exit is rotated such that the gas exit is oriented toward the tilted photomask. ### Claim 13 A photomask purging method, comprising: opening a pod having a photomask therein; moving the photomask from the opened pod to a destination where a gas exit is toward; providing a gas from a gas source to the gas exit; and switching an on/off valve connected between the gas source and the gas exit at a switch frequency, wherein the switch frequency of the on/off valve changes in a sine function. ### Claim 14 (depends on 13) The photomask purging method of claim 13, further comprising: automatedly detecting locations of particles on the photomask prior to opening the pod. ### Claim 15 (depends on 13) The photomask purging method of claim 13, further comprising: automatedly rotating the photomask with respect to a horizontal plane when the photomask is at the destination where the gas exit is toward. ### Claim 16 (depends on 13) The photomask purging method of claim 13, further comprising: rotating the photomask after the photomask is moved to the destination where the gas exit is toward; and rotating the gas exit after rotating the photomask. ### Claim 17 A photomask purging system, comprising: an automated pod opener; a robot arm having a range of motion sufficient to transfer a photomask from the automated pod opener to a destination; and a purging device comprising: a gas exit toward the destination; a gas source; a gas line connecting the gas source and the gas exit; and a flow rate control valve in the gas line, wherein the flow rate control valve is configured to control a gas to flow from the gas source to the gas exit at a periodically variable flow rate, wherein the periodically variable flow rate changes in a sine function. ### Claim 18 (depends on 17) The photomask purging system of claim 17, wherein the robot arm has an end effector that is 360-degree rotatable with respect to a horizontal plane. ### Claim 19 (depends on 17) The photomask purging system of claim 17, wherein the purging device further comprises: an on/off valve in the gas line, wherein the on/off valve has a periodically variable switch frequency. ### Claim 20 (depends on 19) The photomask purging system of claim 19, wherein the periodically variable switch frequency of the on/off valve has a substantially sine wave waveform.