Dry-Etch-induced damage in GaAs investigated via TEM

Abstract

Plasma-assisted etching is an important III-V semiconductor fabrication technique for patterning device structures on the nanometer scale with high accuracy. The quality of the processed surface is of primary importance for most electronic applications. It is well documented that reactive ion etching (RIE), with its high self-biases, usually incurs material damage via ion bombardment which ultimately limits device performance. Magnetron ion etching (MIE) is an attractive alternative to RIE. Specifically, MIE has a lower sheath voltage than RIE and the discharge contains low to moderate energy ions, both of which allow wafer processing with less ion-induced damage. This study investigated the nature and extent of near surface disorder resultant from MIE with freon-12 (CCl2F2) via cross-sectional transmission electron microscopy (TEM). The effect of residual damage on device performance was evaluated via Schottky diode measurements. The GaAs wafers were etched under the following conditions: