In order to simulate diffusion kinetics during thermal treatments in SiGe heterostructures, a physically-based atomistic model including chemical and strain effects was developed and implemented into a non-lattice atomistic kinetic Monte Carlo framework. This model was based on the description of transport capacities of native point defects (interstitials and vacancies) with different charge states in SiGe alloys in the whole composition range. Lattice atom diffusivities were formulated in terms of point defect transport, taking into account the different probability to move Si and Ge atoms. Strain effects were assessed for biaxial geometries including strain-induced anisotropic diffusion, as well as charge effects due to strain-induced modifications of the electronic properties. Si-Ge interdiffusion in heterostructures was analyzed from an atomistic perspective. A limited set of physical parameters were defined, being consistent with previously reported ab initio calculations and experiments. The model was implemented into a non-lattice kinetic Monte Carlo simulator and the relevant implementation details and algorithms were described. In particular, an efficient point defect mediated Si-Ge exchange algorithm for interdiffusion was reported. A representative set of simulated interdiffusion profiles were shown, exhibiting good agreement with experiments.

Physical Modeling and Implementation Scheme of Native Defect Diffusion and Interdiffusion in SiGe Heterostructures for Atomistic Process Simulation. P.Castrillo, R.Pinacho, M.Jaraiz, J.E.Rubio: Journal of Applied Physics, 2011, 109[10], 103502