Abstract: Method and apparatus for masked etching of a polysilicon surface layer or film to expose a dielectric underlying layer or film on a semiconductor material using ion bombardment from an ionized mixture of a fluorine based gas with a chlorine or bromine containing gas. A particularly useful gas is a mixture of sulfur hexafluoride and Freon 115 gases (C.sub.2 ClF.sub.5). The mixture of gases achieves the result of highly selective etching through the polysilicon film without significantly attacking the underlying dielectric film and without significant undercutting in the polysilicon film or etching of the masking layer.

Abstract: Dry plasma etching of a plurality of planar thin-film semiconductor wafers is effected simultaneously and uniformly in a relatively small chamber enveloping a vertically-stacked array of laminar electrode sub-assemblies each of which includes a pair of oppositely-excited electrode plates tightly sandwiching a solid insulating layer of dielectric material, the parallel sub-assemblies being vertically separated to subdivide the chamber into a plurality of reactor regions where RF discharges can excite a normally inert ambient gas to develop reactive plasma for simultaneous planar plasma etching or reactive ion etching (RIE) of all wafers within the several regions.