Dry etch induced damage in GaAs investigated using Raman scattering spectroscopy

Abstract

Raman scattering spectroscopy is used to probe the surface electrical properties (surface depletion width) of GaAs after dry etching in either a reactive ion etching (RIE) system or a remote plasma system. A variety of etch gases (argon, helium, Freon 12, HCl) and biases (−80 to −350 V) are used to examine physically and chemically induced damage. Through the use of wet etches, the dry etch induced damage was observed to be within ∼300 Å of the surface. In the RIE system, etching with argon and helium causes the depletion width to widen, with helium inducing a greater effect. A remote plasma does not cause a change in the depletion width, indicating an absence of energetically damaging species. In contrast to inert gases, etching with reactive gases in both systems reduces the effective surface charge.