Varian Associates, Inc.

Scott C Holden

Norman L Turner

Peter R Hanley

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.

Methods and apparatus for gas-assisted thermal transfer with a

Conductive heat transfer between a thin deformable workpiece and heat sink is optimized by imposing a load over the workpiece resulting in a uniform contact pressure distribution in said workpiece which is also the maximum stress consistent with the elastic properties of the workpiece. The surface of the heat sink is given a contour determined by these criteria for a thin circular disk clamped thereto.

Method for optimum conductive heat transfer with a thin flexible

Optimum surface contour for conductive heat transfer with a thin

Apparatus and method are provided for effecting gas-assisted, solid-to-solid thermal transfer with a semiconductor wafer. A semiconductor wafer is loaded at its periphery onto a shaped platen. Sufficient contact pressure from the loading is produced between the wafer and the platen so that significant gas pressure may be accommodated against the back side of the wafer without having the wafer bow outwardly or break. Gas under pressure is introduced into the microscopic void region between the platen and the wafer. The gas fills the microscopic voids between the platen and semiconductor wafer. The gas pressure approaches that of the preloading contact pressure without any appreciable increase in the wafer-to-platen spacing. Since the gas pressure is significantly increased without any increase in the wafer-to-platen gap, the thermal resistance is reduced and solid-to-solid thermal transfer with gas assistance produces optimum results.

Method for gas-assisted, solid-to-solid thermal transfer with a

Method and apparatus for high speed vacuum pumping of an air lock. A vacuum pumped expansion tank having a volume larger than the volume of the air lock is coupled through a valve to the air lock. When evacuation of the air lock is desired, the valve is opened for a brief duration and the gas in the air lock rapidly expands into the expansion tank. Multiple pumping stages, each including a vacuum pumped expansion tank coupled through a valve to the air lock, can be utilized to decrease the final pressure in the air lock. The valves are sequentially opened to permit sequential expansion of the gas in the air lock into the expansion tanks. Multiple air locks can time share the same pumping system.

Air lock vacuum pumping methods and apparatus

Articles for irradiation are introduced from atmospheric pressure through a vacuum lock to a high vacuum environment for processing. The maintenance of low operating pressures while water vapor is released from the surfaces of the lock and the article is principally achieved by a separate pumping device operating in the high vacuum enclosure, which device preferably takes the form of a large cryo-panel. The cryo-panel can be electrically isolated from ground to provide a charge collection surface within a Faraday cage for ion implantation processing of the article.

Rapid pumpdown for high vacuum processing

For enhanced heat conductive transfer from a semiconductor wafer during ion implantation, the wafer is clamped to a platen having a contour f(r,.theta.) computed to establish uniform contact pressure over said wafer for a number, n, of discrete clamping locii distributed along the periphery of the wafer. The available area of the wafer is thus maximized.

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Manchester, MA, United States of America

Scott C Holden