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With the approval of the program manager, the equipment purchased on this grant was changed to a Plasma Therm, Inc. SLR-770 inductively coupled plasma (ICP) processing system. The SLR-770 has been invaluable in the study of plasma etching of AlGaAsSb and GaSb-materials that form the backbone of antimonide-based semiconductor lasers. AlGaAsSb is especially difficult to pattern with wet chemicals because it is prone to oxidation. The combination of sputtering and chemical etching in plasmas represents the only reproducible means of etching this quaternary alloy. Specifically, we have studied etch rate and selectivity of GaSb and AlGaAsSb in plasmas containing BCl3, Cl2, and Ar as a function of process pressure, DC bias, ICP power, and reactant concentration. Smooth and anisotropic etching was obtained over a variety of process conditions. This research will benefit future efforts to fabricate ridge-waveguide, DFB, and etched mirror laser diodes designed with antimonide semiconductors.