Effects of PCl/sub 3/ addition on ECR CH/sub 4//H/sub 2//Ar plasma etching of InP and InGaAs

Abstract

A hybrid electron cyclotron resonance (ECR)/radiofrequency (RF) plasma etching system used to study the etching characteristics of InP and InGaAs in CH/sub 4/H/sub 2/-based discharges is described. It was found that the materials retain smooth surface morphologies for microwave powers below 150 W. At higher microwave powers the surface becomes rough due to preferential removal of the group V species. The quality of Au Schottky diode contacts on InP degrades for high-bias etching, but the addition of PCl/sub 3/ to the discharge retards this degradation by providing an overpressure of P. The room-temperature photoluminescence intensity of InP is preserved by the PCl/sub 3/ addition. The use of CH/sub 3/Cl in preference to CH/sub 4/ to increase the etch rate of InGaAs was investigated and this appears to have few advantages since the etch rates are comparable to those with CH/sub 4//H/sub 2/. The degree of polymer deposition during CH/sub 4//H/sub 2/Ar etching on the type of mask used (photoresist, W, or SiO/sub 2/) is discussed.<>