Reactive-ion-etch damage in GaAs processing evaluated by a microwave absorption technique

Abstract

Through determination of magnetic field-dependent resistivity by electric microwave absorption (EMA), both mobility and carrier concentration of conducting layers in a semiconducting substrate may be evaluated. We have employed this method to study the extent of electric damage produced during standard GaAs plasma processing; various typical heterostructures were subjected to realistic reactive ion etch treatments and the changes in transport properties were examined by EMA. It was seen that predominantly chemical etch processes result in little substrate damage, whereas physical milling produces considerable degradation. Oxynitride etching was noted to be benign only at low voltages, whereas photoresist stripping was not seen to produce any measurable substrate damage.