BROMINE ION-BEAM-ASSISTED ETCHING OF INP AND GAAS

Bromine ion-beam-assisted etching produces smooth vertical sidewalls i n GaAs wafers with substrate temperatures in the range of 20-200 degre es C and smooth vertical sidewalls in InP wafers with substrate temper atures in the range of 150-200 degrees C. Etch rates can be varied fro m several nm/min to 0.16 mu m/min through the bromine flow rate, Ar+ i on beam density and energy, and the substrate temperature. The etching rate ratios of bromine-only etching (no Art ion beam) to argon ion-be am-assisted bromine etching to argon ion etching (no bromine) with an ion beam density of 40 mu A/cm(2) and ion beam energy of 500 V were me asured to be 11.5:23:1 and 16:125:1 at a substrate temperature of 200 degrees C and 2:42:1 and 1:40:1 at a substrate temperature of 100 degr ees C for GaAs and InP, respectively. Such rate enhancements were foun d to be typical with these materials. Bromine ion-beam-assisted etchin g also: appears to have an advantage over chlorine ion-beam-assisted e tching in that high anisotropy can be achieved with bromine in both th e GaAs and the InP materials systems at substrate temperatures as high as 200 degrees C as compared to chlorine where the etching of GaAs is spontaneous and isotropic at temperatures above 150 degrees C. (C) 19 98 American Vacuum Society.