A SURFACE MODIFICATION STUDY OF INGAP ETCHED WITH AN ELECTRON-CYCLOTRON-RESONANCE SOURCE AT VARIABLE MICROWAVE POWERS

Etch-induced surface modifications, utilizing an electron cyclotron re sonance source, have been studied as a function of controllable etch p arameters. InGaP was etched with BCl3 at a constant substrate temperat ure (100 degrees C) and bias voltage (-145 V) using microwave powers v arying between 250 and 1000 W. The surface morphology, residual etch d amage, and surface stoichiometry were strongly influenced by changes i n ion flux. The etch-induced lattice damage and surface smoothness inc reased as the ion energy was elevated. Low ion flux etching resulted i n an In-enriched P-depleted surface suggesting nonuniform desorption o f InClx which gave rise to the surface roughness observed at the low m icrowave powers. The smooth surfaces, achieved at the higher microwave power levels, were attributed to either efficient sputter-assisted de sorption of the InClx etch products or to InClx desorption via plasma- induced surface heating. Results of this study demonstrate that etchin g at microwave powers between 500 and 750 W induce low residual damage and smooth surfaces while maintaining a reasonable etch rate for devi ce processing. (C) 1996 American Institute of Physics.