Contouring of polished single-crystal silicon plates by wire electrical discharge machining

We investigate the effect of cutting by wire electrical discharge machining (WEDM) on the shape accuracy of polished single-crystal silicon. Single-crystal silicon plates are polished, and then contoured in deionized water or in oil by WEDM. The shape accuracy of the polished surfaces is measured with an interferometer. As a result, the polished surfaces are deformed into convex shapes by WEDM cutting. The polished surfaces tend to become flat as the roughness of the cut sections decreases, and the flatness is independent of the type of cutting liquid. Cutting in oil is advantageous for maintaining the smoothness of polished surfaces. These findings confirm that, in the contouring process of polished single-crystal silicon blocks, smooth and high-accuracy surfaces are achieved by conducting rough- and finish-cutting WEDM processes in oil.