We have studied reactive ion etching of Si1−xGexalloys withx≤0.15 and Ge in HBr plasmas. The etch rate of SiGe increases monotonically with the Ge content of the alloy and for a Si85Ge15alloy was &bartil;50% greater than for Si. Etch profiles are identical to those formed in singe‐crystal Si. X‐ray photoelectron spectroscopy studies shown that the surface of the etched SiGe alloys are depleted in Ge and consist of about one monolayer of brominated Si over the alloy.