Novel plasma chemistries for highly selective dry etching of InxGaN1−x: BI3 and BBr3

There is increasing need for dry etching chemistries with high selectivity for one nitride over another. In high power nitride-based electronic devices, selective removal of InN or InGaN contact layers in HEMTs or HFETs, or base layers in HBTs under low damage condition is necessary. Two new plasma chemistries, BI3 and BBr3 are found to produce maximum etch selectivities of ca. 100 for InN over GaN and AlN in ICP discharges, due to the relatively high volatility of InI3 and InBr3 etch products. Surface morphology of the etched nitrides is found to depend on plasma composition, chuck power and source power, but root-mean-square roughness similar to the as-grown materials are obtained over a wide range of etching conditions.