Selective inductively coupled plasma etching of group-III nitrides in Cl2- and BCl3-based plasmas

Abstract

High-density plasma etching has been an effective patterning technique for the group-III nitrides due to ion fluxes which are two to four orders of magnitude higher than more conventional reactive ion etch systems. GaN etch rates exceeding 0.5 μm/min have been reported in inductively coupled plasma (ICP) etch systems at relatively high dc-biases (>200 V). However, under these conditions, the etch mechanism is dominated by ion bombardment energies which can induce damage and minimize etch selectivity. Development of etch processes with high selectivity has become relevant with recent interest in high power, high temperature electronic devices. In this study, we report ICP etch rates and selectivities for GaN, AlN, and InN in Cl2/Ar, Cl2/N2, Cl2/H2, Cl2/SF6, BCl3/Ar, BCl3/H2, BCl3/N2, and BCl3/SF6 plasma chemistries.