Etching of Ga-based III - V semiconductors in inductively coupled Ar and -based plasma chemistries

Abstract

We report results of a study on the inductively coupled plasma (ICP) etching of GaAs, AlGaAs, GaSb, and GaP in pure Ar, and plasma chemistries. Etch rates of the semiconductors initially increase with ICP source power, reaching maxima around 1500 - with - 700 W ICP power, and then decrease with further increase of ICP power because of the decrease in cathode dc self-bias. Etch rates increase at fixed ICP power with rf chuck power in the range of 100 W to 450 W, while they showed little dependence on the chamber pressure (2 mTorr - 20 mTorr) in discharges. We found that the dc self-bias on the rf chuck decreased exponentially as ICP power increased, while it increased with rf chuck power and pressure in these plasma chemistries. A simple calculation of ion flux and etch yield based on dc self-bias of the plasmas on the sample chuck was used to measure typical values of etch yield. In both ICP and discharges these were close to the pure Ar sputter yield.