Plasma Etching PROMS and Other Problems

Plasma etching or low temperature ashing with an RF field has found numerous applications in semiconductor processing and production. The advantage is a dry procedure with the introduction of no "wet" solutions. If a primary gas containing fluorine is introduced into the field, active fluorine ions are produced, which vigorously attack silicon and silicon dioxide, but, very importantly, do not attack metallic aluminum or nichrome. This selectivity of etch is of great advantage in the-removal of glass passivation from atop aluminum interconnects and fusible nichrome links. With the aid of an electron microprobe and a plasma etcher, fused nichrome links in PROMS were studied to determine the location and movement of the metal before and after fusion. Some examples of the use of plasma etching in lieu of wet chemical stripping of glass passivation are presented. And, finally, the use of plasma etching to facilitate the study of aluminum alloying into contact windows is described.