Effect of inert gas additive species on Cl2 high density plasma etching of compound semiconductors Part I.: GaAs and GaSb

The role of the inert gas additive (He, Ar, Xe) to Cl-2 Inductively Coupled Plasmas for dry etching of GaAs and GaSb was examined through the effect on etch rate, surface roughness and near-surface stoichiometry. The etch rates for both materials go through a maximum with Cl-2% in each type of discharge (Cl-2/He, Cl-2/Ar, Cl-2/Xe), reflecting the need to have efficient ion-assisted desorption of the etch products. Etch yields initially increase strongly with source power as the chlorine neutral density increases, but decrease again at high powers as the etching becomes reactant-limited. The etched surfaces are generally smoother with Ar or Xe addition, and maintain their stoichiometry. (C) 1999 Elsevier Science B.V. All rights reserved.