| 摘要 |
PROBLEM TO BE SOLVED: To reduce a supply amount of gas for a gas curtain that is formed in an EUV light extraction unit, and to minimize effects on an internal pressure of an EUV light-source unit and an exposure system.SOLUTION: EUV light emitted from a discharge unit 1 is converged by an EUV converging mirror 2 and is guided to the exposure system 31 in an exposure system housing 30 via an opening in the EUV light extraction unit 4. To prevent debris generated in the EUV light-source unit 10 from entering the exposure system 31, a gas-feed port 22 and an exhaust port 23 are arranged in the EUV light extraction unit 4 and the gas curtain is formed by flowing gas so that it may traverse the EUV light extraction unit 4. When light exposure is not performed, the EUV light-source unit stops operations (burst operations) for emitting light by pulse-like discharge and does not supply gas for forming the gas curtain or reduces the supply amount during this period. In this way, the amount of stop gas can be reduced. |
