Importance

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Abstract

A stage for processing a substrate, especially useful for vacuum applications, has a recess just large enough to hold a substantially flat substrate and a chuck or holder, but not much more. The perimeter of both top and bottom of the stage has air bearing surfaces separated from the recess by differentially pumped grooves and seal lands. The air bearing lands are guided between two reference surfaces and the seal lands, being substantially coplanar, create a resistance to flow between the bearings and the recess. On the other side of one of the reference plates mounts the radiation source or process. The opposite reference plate may have a large aperture, non-contact pumping port. This improves vacuum capability and stage precision. The stage may operate in a vacuum environment itself or can provide multiple stages moving between processes or inspection steps within the same tool or process sequence.

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First Claim