Inductively coupled plasma (ICP) operated in the reactive-ion etching mode is used for mesa etching of InP using Cl-2/N-2 chemistry with a Ni metal mask. Etch rates of approximately 140 nm/min with very smooth and vertical sidewalls are obtained at a dc bias of 120 V. The effects of temperature, gas flow, chamber pressure, ICP source power, and substrate bias power on etch rate are studied; sidewall profile and surface morphology will be discussed. (C) 2004 American Vacuum Society.