Effect of inert gas additive species on Cl-2 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 o n etch rate, surface roughness and near-surface stoichiometry. The etch rat es for both materials go through a maximum with Cl-2% in each type of disch arge (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 s trongly with source power as the chlorine neutral density increases, but de crease again at high powers as the etching becomes reactant-limited. The et ched surfaces are generally smoother with Ar or Xe addition, and maintain t heir stoichiometry. (C) 1999 Elsevier Science B.V. All rights reserved.