Understanding of etch mechanism and etch depth distribution in inductivelycoupled plasma etching of GaAs

We investigated etch mechanism and etch depth distribution on GaAs wafers i n inductively coupled plasma etching. Effects of two plasma chemistries for GaAs etching were also investigated. One chemistry was BCl3/N-2 for equal- rate etching of GaAs over AlGaAs. The other chemistry was BCl3/SF6/N-2/He f or selective etching of GaAs over AlGaAs. The experimental results showed t hat there was an identical trend of etch depth distribution over the wafers with each process. In plasma etching of GaAs/AlGaAs, etch rate at the cent er of the wafer was always lower than that at the edge of the wafer. The re sults indicate that etch mechanism of the processes is neutral etch reactan t limited. (C) 2001 Published by Elsevier Science Ltd.