MODELING OF ION-IMPLANTATION IN SINGLE-CRYSTAL SILICON

In this paper are described ion implant models that have been developed at the University of Texas at Austin. In this activity the strategy consists of the development of computationally-efficient semi-empirical models and physically-based, more computationally intensive Monte Carlo models. The Dual-Pearson approach has been highly successful in the semi-empirical model development, because of its ability to account so well for the dependence of both the randomly scattered and the channeled parts of the implanted profile on all of the key implant parameters. The physically-based Monte Carlo models provide the theoretical foundation required for technology development and process control, and they serve as the basis for much of the computationally-efficient semi-empirical models. Depth profile models for B, BF2, and As implants into single-crystal silicon, and a depth profile model for B implants through oxide layers into single-crystal Si have been developed. An accurate Monte Carlo simulator for boron implants into single-crystal Si or through oxide layers into single-crystal Si has also been developed. This simulator includes dependences on implant beam divergence, wafer temperature, and it has a new local-electron electronic stopping power model with explicit dependence on the local electron density in the Si lattice. In addition, we have developed a cumulative damage model for predicting the dose dependence and the resulting interstitial and vacancy distributions. We have also developed Monte Carlo simulators for BF2 and As implants into single-crystal Si. The semi-empirical and physically-based models have been applied to develop a 2-dimensional model for boron implants through oxide layers into single-crystal Si. This computationally-efficient model has explicit dependence on energy, oxide thickness, dose, tilt angle, rotation angle, mask thickness, and mask edge orientation.