Semiconductor wafer fixture for alignment in a grating exposure process

Abstract

A fixture and method for providing accurate and repeatable alignment and attachment of a semiconductor wafer to a corner cube exposure fixture includes a vacuum-assisted wafer holder of rectangular shape. The wafer holder is first placed upon an L-shaped loading fixture so that a wafer may be positioned against the front surface of the holder and manipulated until the pair of wafer flats abut each leg of the L-shaped fixture. When so aligned, a vacuum is applied to secure the attachment and alignment of the wafer vis-à-vis the wafer holder. The wafer holder is thereafter inserted in a corner cube exposure fixture, where the fixture is formed to include a right-angle bracket with alignment features formed in one leg of the angle. The wafer holder also includes alignment features in its bottom surface, where these features are formed to mate with the bracket upon attachment. The proper placement and alignment of the wafer holder to the exposure fixture results in the wafer being disposed immediately adjacent to the reflective surface used to form the interference pattern on the wafer surface. The right angle in the fixture ensures that the mirror surface remains orthogonal to the wafer surface such that a uniform grating may be formed across the wafer surface.