Inductively coupled plasma etching of GaN and its effect on electrical characteristics

Abstract

Dry etch behavior in the inductively coupled plasma processing of GaN using SF6/N2 plasma has been found to be highly ion induced with an ion energy threshold of about 100 eV. Temperature dependence of the etch rate indicates a small kinetic component. Maximum etch rate of 67 nm/min and good anisotropy have been demonstrated. The most efficient etch regime is observed for an ICP source power between 500–1000 W where the etch mechanism is ion limited. In contrast to reactive ion etching induced damage behavior, almost ideal diodes are obtained at the higher dc bias condition (300 V). X-ray photoelectron spectroscopy and atomic force microscopy studies indicate that smooth surface with minimal surface contamination, coupled with the incorporation of N on the substrate surface help to produce ideal diodes on surfaces etched at 300 V. Sidewall depletion is found to be in the range of 65 nm at the given SF6/N2 plasma process conditions.