Mechanisms of isotropic and selective etching between SiGe and Si

The impact of SiGe isotropic etching selectively to Si on structures such as silicon on nothing or gate all around has been evaluated through the electrical performances of devices that were subjected to different etching processes. New prospects and evolutions in microelectronics can be foreseen, thanks to the development of the opposite process, i.e., the isotropic etching of Si selectively to SiGe. This process is based on the passivation of the SiGe layer during etching in a chemical dry etching tool. Scanning electron microscopy and x-ray photoelectron spectroscopy studies allowed the analysis of the influence of each parameter (gas mixture, pressure, and microwave power) and the proposal of etching and passivation mechanisms. This led to the definition of a highly selective Si:SiGe process.