Interstitial charge states in boron-implanted silicon

Abstract

It is becoming increasingly clear that simulation models of transient enhanced diffusion (TED) in silicon need to incorporate interstitial charging effects accurately in order to adequately reproduce experimental data near the surface and near the underlying junction. However, in the case of boron TED, the relevant charge states and ionization levels of both boron and silicon interstitial atoms are known only imperfectly. The present work attempts to describe this behavior more accurately via simulations of implanted profiles that employ a model whose kinetic parameters have been determined with considerable confidence by rigorous systems methods. The results suggest that B has two relevant charge states: (+) and (−). The corresponding states for Si are (++) and (0). The effective ionization levels for B and Si are 0.33±0.05 and 0.12±0.05eV above the valence band maximum, respectively.