CHLORINE-BASED SMOOTH REACTIVE ION-BEAM ETCHING OF INDIUM-CONTAINING III-V COMPOUND SEMICONDUCTOR

Very smooth and vertical etching of InP by Cl2 reactive ion beam etching has been achieved under high temperature (almost-equal-to 200-degrees-C), high ion energy (almost-equal-to 1 keV) and low Cl2 pressure (approximately 10(-5) Torr). The roughness is estimated to be a few nm by scanning tunneling microscopy and no contamination except for Cl was observed by in situ Auger electron spectroscopy. Under these etching conditions, the etched depth is precisely controlled (sigma = 22 nm) by simply monitoring the electrode curtent of the ion accelerating grid. Other III-V compound semiconductors, such as GaAs, InGaAs, AlGaInP and InAlAs have also been etched smoothly and vertically. Multilayers of these materials, such as InP/InGaAsP, AlGaInP/GaInP, and InAlAs/InGaAs/InP have been etched without steps between the layers on the sidewalls.