Dopant diffusion modeling for heteroepitaxial SiGe∕Si devices

A comprehensive model to predict dopant diffusion (Sb, As, B, and P) in epitaxially strained silicon germanium (SiGe) CMOS transistors is presented. The effect of germanium is primarily comprehended as a change in point defect populations (self-interstitials and vacancies). Our analysis validates this approximation for most dopants (Sb, As, Ge, and P). With germanium concentration, the vacancy population increases much more than the interstitial concentration. Consequently, the fractional interstitial mediated diffusion decreases with increasing germanium. For boron an additional change in pair formation/migration energy is required to explain the observed experimental data. The model is used to explore heteroepitaxially grown SiGe∕Si device design options.