Technology Computer-Aided Design Model for SiGe Oxidation and Ge Diffusion Along Oxide/SiGe Interfaces

During the oxidation of SiGe regions, Si is preferably incorporated into the oxide, while Ge atoms accumulate at the SiGe side of the interface. Moreover, during oxidation of fin structures of Si/SiGe superlattices, Ge atoms diffuse from SiGe regions to Si regions along the oxide/SiGe interface, as recently reported. This surface diffusion can be used for the formation of Si nanowires surrounded by SiGe, and possibly for the fabrication of gate all-around transistors. Herein, a new process simulation model is presented which describes SiGe oxidation and the diffusion of Ge atoms along the interface. During oxidation, Ge atoms can be trapped at the oxide/SiGe interface, diffuse along the interface, and be re-emitted into the SiGe bulk. The model reproduces measured oxidation rates, the pileup of Ge atoms at the SiGe side of planar oxide/SiGe interfaces, the injection of self-interstitials and the reduction of vacancies at oxidizing SiGe surfaces, and the recently reported diffusion of Ge atoms along the surface of fin structures made of Si/SiGe superlattices. A process model for the oxidation of SiGe is presented. It describes the Ge pileup at the oxide/SiGe interface and, for the first time, the diffusion of Ge along the interface inside a thin interface layer. The model reproduces published transmission electron microscopy data that monitor the diffusion of Ge in fin structures of Si/SiGe superlattices.image (c) 2024 WILEY-VCH GmbH