Inductively coupled plasma etching of III-V nitrides in CH4/H-2/Ar and CH4/H-2/N-2 chemistries

Inductively coupled plasma (ICP) etching of GaN, AlN, InN, InGaN, and InAlN was investigated in CH4/H-2/Ar and CH4/H-2/N-2 plasmas as a function of dc bias, ICP power, and pressure. The etch rates were generally quite low, as is common for III-nitrides in CH4-based chemistries. In CH4/H-2/Ar plasmas, the etch rates increased with increasing de bias. At low radio frequency power (150 W), the etch rates increased with increasing ICP power, while at 350 W radio frequency power, a peak was found between 500 and 750 W ICP power. The de bias was found to increase with increasing pressure. The etch rates in the CH4/H-2/N-2 chemistry were significantly lower, with a peak at 500 W ICP power. The etched surfaces were smooth, while selectivities of etch were less than or equal to 6 for InN over GaN, AlN, InGaN, and InAlN under all conditions.