Selective etching of a SiGe layer for Si/SiGe/Si stacked layers was investigated for device applications. The SiGe layer is selectively and laterally etched by a HF:HNO3:H2O solution after patterning the layers. The selective etching rate of the SiGe layer increased as the Ge ratio increased. The etching rate of a SiGe layer annealed at 800°C did not change from an as-grown sample, and the Ge diffusion into Si was very small. However, the etching rate of a layer annealed at 1000°C was found to have decreased, and Ge diffused into Si in large amounts. This indicates that annealing at less than 800°C is suitable for device applications.