Identification of volatile products in low pressure hydrocarbon electron cyclotron resonance reactive ion etching of InP and GaAs

Volatile species produced during CH4/H2 and CH4/H2/Ar electron cyclotron resonance (ECR) reactive ion etching (RIE) of InP and GaAs at pressures of 2 mTorr have been investigated with secondary ion mass spectrometry diagnostics. A CH4/H2 ECR plasma with −120 V rf bias on the sample stage is found to etch InP but not GaAs. However, etching of GaAs does occur at this bias if the CH4/H2 mixture is diluted with Ar, showing the importance of …