Inventors:
Bjorn O. Pedersen - Chelmsford MA
Jonathan A. Jost - Rockport MA
Assignee:
Varian Associates, Inc. - Palo Alto CA
International Classification:
F28F 900
Abstract:
Apparatus for providing thermal transfer between a semiconductor wafer and a heat sink or source in a vacuum processing chamber includes a platen against which the wafer is sealed to define a thermal transfer region therebetween. The platen includes a passage for gas flow between the chamber and the thermal transfer region and a conduit for circulation of a cooling fluid. The platen further includes a fluid-actuated valve responsive to the pressure of the cooling fluid for closing the passage. When the pressure in the chamber reaches a predetermined value, the cooling fluid is turned on and closes the valve. Gas at the predetermined pressure, typically in the range of 0. 5 to 100 Torr, is trapped in the thermal transfer region and conducts thermal energy. In a preferred embodiment, a plurality of platens are positioned on a rotating disc in an ion implantation system.