Effects of ion species and adsorbed gas on dry etching induced damage in GaAs

Abstract

Dry etching techniques which induce minimum damage on the etched surfaces are essential for submicrometer device fabrication. In this study, damage induced in GaAs by ion-beam etching and ion-beam-assisted etching was found to be affected by ion energy, ion mass, and adsorbed gas on the sample surfaces during etching. The etching characteristics of Ne, Ar, and Xe ions with energies ranging from 250 to 2000 eV were studied. The effect of gas adsorption was investigated by using Cl2 (reactive gas for GaAs) and NO2 (nonreactive gas for GaAs) with gas fluxes equivalent to pressures between 2 and 50×10−4 Torr. Dry etching induced damage was evaluated by measuring electrical characteristics of Schottky diodes fabricated on the etched GaAs surfaces. Our results indicated that damage in GaAs can be minimized by reducing the ion penetration distance into the substrate by using low ion energy and heavy ion species, and by introducing adsorbed gas, such as Cl2 or NO2, on the sample surface as a protective layer.