A Highly Selective, Chlorofluorocarbon‐Free GaAs on AlGaAs Etch

Abstract

A highly selective reactive ion etching process using , , , and He is reported. The selectivity of the etch, which is adjustable, ranges from 308:1 to 428:1 for to . This variability in selectivity is achieved by adjusting the helium flow rate. One very attractive feature of this etch is that it uses no chlorofluorocarbons and therefore complies with future bans on these substances imposed at both federal and corporate levels.1–3 The etch is demonstrated on a field effect transistor structure with an underlying stop‐etch layer. The etch can be used for both anisotropic and isotropic applications.