MODELING OF ION-IMPLANTATION IN SINGLE-CRYSTAL SILICON

In this paper are described ion implant models that have been develope d at the University of Texas at Austin. In this activity the strategy consists of the development of computationally-efficient semi-empirica l models and physically-based, more computationally intensive Monte Ca rlo models. The Dual-Pearson approach has been highly successful in th e semi-empirical model development, because of its ability to account so well for the dependence of both the randomly scattered and the chan neled parts of the implanted profile on all of the key implant paramet ers. The physically-based Monte Carlo models provide the theoretical f oundation required for technology development and process control, and they serve as the basis for much of the computationally-efficient sem i-empirical models. Depth profile models for B, BF2, and As implants i nto single-crystal silicon, and a depth profile model for B implants t hrough oxide layers into single-crystal Si have been developed. An acc urate 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, wafe r temperature, and it has a new local-electron electronic stopping pow er 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 f or BF2 and As implants into single-crystal Si. The semi-empirical and physically-based models have been applied to develop a 2-dimensional m odel for boron implants through oxide layers into single-crystal Si. T his computationally-efficient model has explicit dependence on energy, oxide thickness, dose, tilt angle, rotation angle, mask thickness, an d mask edge orientation.