Dry etching with xenon difluoride (XeF2) is a well-known process for the isotropic removal of silicon. The etching of silicon-germanium alloys with XeF2, however, has not yet been investigated. Here, the XeF2 dry etching of SiGe alloys was characterized versus composition and XeF2 partial pressures. It was found that the etch rates showed a strong dependence on Ge content of the etched materials. The roughness of the etched surfaces was also investigated. This study provides etch rates versus process conditions and etched surface roughness, which are useful for accurately fabricating SiGe-based structures and devices. (c) 2008 American Vacuum Society.