An extremely high vacuum (xhv) has come to attract attention in situations not only of production, but also utilization. The mechanism of cryopumping has the most superior advantages as a pump for xhv use. In order to extract the advantages and to put xhv into practical use, a cryopump whose pumping section is all metal and is able to be separated completely from the refrigerator has been developed. Using this pump, xhv below 1 x 10(-10) Pa was achieved and in the case of pumpdown from the atmospheric pressure without bakeout, the chamber pressure of the order of 10(-9) Pa was obtained in 6 h, and xhv of the order of 10(-10) Pa was obtained in 48 h from the roughing start This pump has been applied to the equipment for the experiments under pressures of the xhv region on the surface structures of silicon. The equipment provided with sample, sample holder, heating device and analyzing devices has achieved xhv below 1 x 10(-10) Pa and maintained xhv of the order of 10(-10) Pa for more than 1000 h. Even in the case where the sample was heated to 800-degrees-C, the chamber pressure had maintained xhv of the order of 10(-10) Pa.
