Refrigeration – Low pressure cold trap process and apparatus
Patent
1999-01-12
2000-09-12
Doerrler, William
Refrigeration
Low pressure cold trap process and apparatus
B01D 800
Patent
active
061160326
ABSTRACT:
A method for reducing particulate generation from regeneration of cryogenic vacuum pumps. The method comprises controlling a pressure ramp rate inside the cryopump during an initial introduction of a regeneration gas into the cryopump. Preferably, the pressure ramp rate is controlled by maintaining a first pressure ramp rate, preferably between about 0.03 T/s and 0.15 T/s, until a first pressure of about 0.3 T is reached inside the cryopump and maintaining a second pressure ramp rate between about 1 T/s and 5 T/s until the surface in the cryopump reaches an intermediate temperature between about 40 K and 100 K. Preferably, the temperature ramp rate is also controlled by heating the surface at a temperature ramp rate between about 0.1 K/s and about 0.5 K/s until the intermediate temperature has been reached. Preferably, the temperature ramp rate is controlled by regulating the flow of an inert gas into the cryopump using a flow restriction device. Alternatively, the second stage cryoarray temperature is increased at the rate of between 0.1 K/s and 0.5 K/s using a PID controlled heater.
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Clawson Daniel O.
Mori Glen T.
Applied Materials Inc.
Doerrler William
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