Abstract: Apparatus and method for vacuum pumping an enclosed chamber includes a cryogenic pumping device in fluid communication with the chamber for removing gases from the chamber. The cryogenic pumping device includes a cooled pumping surface and an expander for expanding a compressed gas and thereby cooling the pumping surface. The vacuum pumping apparatus further includes a sensor for sensing an operating parameter, such as temperature, of the cryogenic pumping device and a controller responsive to the sensor for controlling the operating speed of the expander to produce a desired value of the operating parameter. Typically, the sensor is a temperature sensor, and the controller controls the speed of the expander motor.

Abstract: Apparatus for vacuum pumping an enclosed chamber includes a cryopump in gas communication with the chamber for removing gases by cryocondensation and cryotrapping and an auxiliary pumping device for removing gases that are difficult to remove by cryocondensation or cryotrapping. The cryopump does not contain a sorbent material for cryosorption. As a result, the potential for contamination by a sorbent material is eliminated. The auxiliary pumping device can comprise an ion pump or a turbomolecular vacuum pump. When an ion pump is used, the ion pump is inactivated during periods of high gas loading in the chamber. The vacuum pumping apparatus is particularly useful for vacuum pumping of a plasma vapor deposition chamber.