Processing silicon wafers employing processing gas atmospheres of similar molecular weight
AssigneeThermco Products Corporation
InventorsRobert D. Arrasmith, Thomas R. Barnhart, Jon C. Goldman
Life of this patent
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Abstract
At atmosphere X and an atmosphere Y, which may be an oxidizing atmosphere, are used in a process wherein silicon wafers are processed in a processing chamber, which is pressurized sequentially with a purging atmosphere, with the atmosphere X, and with the atmosphere Y displacing the atmosphere X excpet for a residual portion remaining with the atmosphere X and diminishing in concentration with time. As the atmosphere X has a molecular weight approximating the molecular weight of the atmosphere Y, stratification is minimized. If the atmosphere Y is steam, the atmosphere X may be a premixture of helium and oxyen.
Claims25
In a process wherein silicon wafers are processed in a processing chamber, which is pressurized sequentially with an atmosphere X, and wherein an atmosphere Y displaces the atmosphere X except for a residual portion remaining with the atmosphere Y and diminishing in concentration with time, an improvement wherein the atmosphere X has a mean molecular weight substantially similar to a mean molecular weight of the atmosphere Y, in order to eliminate stratification of atmosphere X with respect to atmosphere Y during the period that atmosphere Y is displacing atmosphere X by causing a density of atmosphere X to be substantially equal to a density of atmosphere Y.
A process for treating silicon wafers in a gas processing chamber comprising the steps of loading one or more wafers into said processing chamber with said wafers having surfaces to be treated and said wafers being positioned so that portions of said wafer surfaces are displaced upwardly from other portions of said wafer surfaces;
- providing a first gas and a second gas for treating said wafers, said gases having differing mean molecular weights;
- mixing a third gas with one of said first and second gases to obtain first and second atmosphere gases respectively, which atmosphere gases have substantially similar mean molecular weights and densities;
- introducing said first atmosphere gas into said chamber and treating said wafer surfaces;
- and flowing said second atmosphere gas into said chamber to displace said first atmosphere gas therefrom and treating said wafer surfaces, said substantial similarity in mean molecular weights and densities being such as to permit displacement of said first atmosphere gas with no stratification of said atmosphere gases into layers in said chamber.
Dependencies are inferred from the claim text.