An Improved Approach to Accurately Model Shallow B and BF₂ Implants in Silicon

In this paper, an improved modeling approach is described for simulating as-implanted boron impurity profiles for B⁺ and BF₂ ⁺ implants into single-crystal silicon. This method uses the sum of two Pearson distribution functions to account for the nonchanneling and channeling components of the implant distribution. The ratio of the two Pearson functions varies with dose, which accounts for the change in the degree of channeling with dose. This modeling approach has been compared with experimentally measured SIMS profiles for a wide range of energies and doses for shallow B⁺ and BF₂ ⁺ implants. The excellent agreement indicates that this method offers a large improvement in simulation capability for B⁺ and BF₂ ⁺ implants. In addition, this method should be applicable to accurately model other impurities which have channeling tendencies.