Response surface study of inductively coupled plasma etching of GaAs/AlGaAs in BCl3/Cl-2

A central composite design response surface study was used to determine the etching characteristics of GaAs/AlGaAs in high-density inductively coupled BCl3/Cl-2-based plasmas as a function of process parameters including indu ctive power, substrate bias, and pressure. Equietch rates were obtained for GaAs and AlxGa1-xAs in the entire parameter space investigated and ranged from approximately 0.3 to 1.0 mu m/min. The etch rate of GaAs/AlGaAs grew w ith an increase in all three parameters. Variations in inductive power had the maximum effect on the etch rate while the bias affected the etch rate t he least. In contrast, bias prayed a significant role in the etch rate of p hotoresist indicating different mechanisms for resist etching. An ion energ y threshold was observed for resist etching which was found to increase wit h decreasing inductive power. Anisotropic GaAs/AlGaAs etch profiles were ob tained over a wide range of parameters including very low substrate bias. E xtremely smooth etched surfaces were observed for most etch conditions. (C) 1999 American Vacuum Society. [S0734-2101(99)01501-8].