The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Sep. 17, 1985
Filed:
Jun. 09, 1983
Scott C Holden, Manchester, MA (US);
Varian Associates, Inc., Palo Alto, CA (US);
Abstract
Methods and apparatus for differential pumping of a thermal transfer gas used to transfer thermal energy between a semiconductor wafer and a platen during processing in a vacuum chamber. Housing structure defines an intermediate region adjacent to and surrounding the platen. The gas, which is introduced into a thermal transfer region behind the wafer, is restricted from flowing into the intermediate region by intimate contact between the wafer and the platen. A clamping ring, which clamps the wafer to the platen, and a bellows coupled between the clamping ring and the housing restrict flow of gas from the intermediate region to the vacuum chamber. The intermediate region is vacuum pumped to a pressure lower than the pressure in the thermal transfer region whereby leakage of the gas into the vacuum chamber is reduced.