CHLORINE AND HCL RADICAL BEAM ETCHING OF III-V-SEMICONDUCTORS

This work presents etch rate versus temperature data for GaAs and InP etched by Cl2 and HCl both with and without a remote plasma. The data is described both qualitatively and quantitatively by a thermodynamic model utilizing reactant-flux-limited and product-desorption-limited regimes. This "ionless" etching technique demonstrates reactant-flux-limited, temperature-independent behavior for HCl etching of GaAs for over five orders of magnitude of flux. InP and GaAs show nearly equirate etching at T > 150-degrees-C with both gases. Reactive ion etching (RIE) with Cl2 of InP at elevated temperatures produces only moderate rate enhancements; RIE gave a maximum etch rate of-approximately-800-angstrom/min at 175-degrees-C compared to-approximately-0.5 mu-m/min obtained with the remote plasma system at the same temperature.