High-density plasma etching of compound semiconductors

Inductively coupled plasma (ICP) etching of GaAs, GaP, and InP is reported as a function of plasma chemistry, chamber pressure, rf power, and source power. Etches were characterized in terms of rate and anisotropy using scanning electron microscopy, and root-mean-square surface roughness using atomic force microscopy. ICP etch rates were compared to electron cyclotron resonance etch rates for $Cl2/Ar$⁠, $Cl2/N2$⁠, $BCl3/Ar$⁠, and $BCl3/N2$ plasmas under similar plasma conditions. High GaAs and GaP etch rates (exceeding 1500 nm/min) were obtained in $Cl2$-based plasmas due to the high concentration of reactive Cl neutrals and ions generated as compared to $BCl3$-based plasmas. InP etch rates were much slower and independent of plasma chemistry due to the low volatility of the In$Clx$ etch products. The surface morphology for all three materials was smooth over a wide range of etch conditions.