Ab-initio calculations to predict stress effects on defects and diffusion in silicon

Stress effects play an increasing role in processing and performance of current nanoscale ULSI devices. In this paper, we show how first principle calculations can be used to predict stress effects on equilibrium concentration and diffusion of defects in silicon. The method used is capable of treating arbitrary strain states, which is an extension beyond the hydrostatic case. For biaxial strain, we find strongly anisotropic diffusion of interstitials (1). We also extended our analysis to B and found similar behavior, leading to the prediction of enhanced lateral diffusion in strained Si on SiGe structures.