Wafer chuck featuring reduced friction support surface

Abstract

Grinding, lapping and polishing basically work by making scratches in the body being ground, lapped or polished. The scratches typically are linear. The scratches gives rise to a directionality component of friction: the friction coefficient is less in the direction along the scratch than in a direction orthogonal, or across, the scratch. In a wafer handling/chucking situation, one wants the wafer to settle on the chuck, which involves the outer regions of the wafer moving radially with respect to the chuck. One can reduce friction in the radial direction by giving the lapping scratches a preferred orientation, namely, radial. This can be achieved by making the final passes of the lapping tool move predominantly in radial directions.

Dependencies are inferred from the claim text.