ECR plasma etching of GaN, AlN and InN using iodine or bromine chemistries

The dry etching characteristics of GaN, AlN and InN in HI-H₂ -Ar and HBr-H₂-Ar were examined using electron cyclotron resonance discharges operating at high microwave power (1000 W) and low pressure (1 mtorr). For an RF-induced DC bias of -150 V, the HI chemistry provides ~20% faster etch rates for GaN and AlN than more conventional chlorine-based plasmas. For InN the rates were up to a factor of 5 faster. The HBr chemistry produced slower etch rates for all three nitrides compared to chlorine chemistries. Highly anisotropic etched features were obtained in the three materials with both iodine and bromine chemistries