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Abstract

An apparatus and method reduce temperature variation across a reticle so as to reduce the expansion variation of the reticle. One method for realizing reduced temperature variation is to fill an inner space with backfill gas under pressure, using distribution trenches and walls (e.g., flow restriction dams), rather than providing uniform backfill gas pressure across the entire reticle. In another method, the perimeter of inner space can be chosen to reduce the expansion variation across the reticle based on the functional relationship between expansion and temperature for the reticle material. In an optional or alternative approach, reduced temperature variation across the reticle can be obtained by selectively filling cavities in the interior of the fluid cooled chuck with backfill gas.

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First Claim