| 摘要 |
PROBLEM TO BE SOLVED: To shorten the time required until the purity of a gas reaches an exposable level when the gas inside a container is replaced by a method wherein the gas inside the container is replaced by a second gas from a first gas, the second gas is supplied to a static-pressure-gas bearing. SOLUTION: When a wafer stage is used, a nitrogen supply valve 38 is closed, the supply of nitrogen to a gas bearing (a linear He bearing) 6 is stopped, a high-pressure He supply valve 38 is opened only for a set time, and He is supplied to the gas bearing 6. Then, a vacuum evacuation valve 40 is opened, and the vacuum evacuation of a chamber 13 is started. When it is conformed that the chamber 13 is vacuum-evacuated down to a prescribed pressure, the vacuum evacuation valve 40 is closed, and a bypass valve 17 is closed. Then, an evacuation valve 23 for a beam line 15 is set to a higher vacuum, an He supply valve 27 is opened regarding the chamber 13, and He is introduced so as to be filled until a pressure inside the chamber 13 becomes a prescribed pressure.
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