| 摘要 |
PURPOSE:To contrive to shorten the evacuation recycle of the title device by a method wherein a vacuum pump capable of evacuating in lower vacuum and a vacuum pump capable of evacuating in higher vacuum are used together and these pumps can be selectively changed-over. CONSTITUTION:A preparatory chamber 15, wherein a smaple 11 for exposure has been set, is first evacuated by an oil rotary pump 31. When the vacuum degree of the preparatory chamber 15 has reached a prescribed value, for example, 10 torrs, a valve 34 is opened. When the capacity of an expansion container 32 has a ratio so high that 10 times, for example, for that of the preparatory chamber 15, a valve 33 is shut and a valve 16 is opened, because the respective vacuum degree of the preparatory chamber 15 and the container 32 reaches nearly 1 torr. According to such a design, the preparatory chamber 15 can be evacuated from a vacuum degree of 1 torr by a turbo-molecular pump 17. When the vacuum degree of the preparatory chamber 15 has reached a value, at which the sample 11 can be exchanged between a sample chamber 12 and the preparatory chamber 15, a gate valve 14 is opened and the sample exchange is performed. By using the pump 17 and the pump 31 together in such a way, the interior of the preparatory chamber 15 can be effectively evacuated. |
