Comprehensive model for nitrogen diffusion in silicon

Nitrogen implantation allows the implementation of varying oxide thickness in the same process. At IEDM 2000, we have shown an integrated nitrogen diffusion-oxidation model to predict the gate oxide thickness. In this paper, we describe further experiments and modeling to explain the diffusion behavior of implanted nitrogen in silicon that lead to a substantial improvement in both the extent of data fit and understanding of the process physics. We show that the model is consistent with three new experimental studies. The improved model now predicts the formation of extended defects from nitrogen implants, correlates well with positron annihilation studies, and agrees with the diffusion results when the damage is changed by co-implants of silicon. The improved model is valid over a wider range of conditions.