An electric stopping power model for Monte Carlo and molecular dynamics simulation of ion implantation into silicon

Abstract

that its use would not infringe privately owned rights. Reference herein to any spccific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, m m - Abstract -We develop a phenomenological model of electronic stopping power for modeling the physics of ion implantation into crystalline silicon. In the framework of effective charge theory, this electronic stopping power for an ion is factorized into (i) a globally averaged effective charge taking into account effects of close and distant collisions by target electrons with the ion, and (ii) a local charge density dependent electronic stopping power for a proton. This model is implemented into both molecular dynamics and Monte Carlo simulations. There is only one free parameter in the model, namely, the one electron radius r: for unbound electrons. By fine tuning this parameter, it is shown that the model can work successfully for both boron and arsenic implants. We report that the results of the dopant profile simulation for both species are in excellent agreement with the experimental profiles measured by secondary-ion mass spectroscopy (SIMS) over a wide range of energies and with different incident directions. This model also provides a good physically-based damping mechanism for molecular dynamics simulations in the electronic stopping power regime, as evidenced by the striking agreement of dopant profiles calculated in the molecular dynamics simulations with the SIMS data.

Efficient molecular dynamics scheme for the calculation of dopant profiles due to ion implantation

“…We are unable to reproduce published SIMS data for Al implants 27 with our current model. This discrepancy is currently being investigated; our findings will be published separately 13 . We can calculate the dopant profile to concentrations one or two orders of magnitude below that measurable by SIMS for the channeling tail of low dose implants.…”

“…A new model that involves both global and local contributions to the electronic stopping is used for the electronic energy loss 6,12,13 . This modified Brandt-Kitagawa 14 model was developed for semi-conductors and contains only one fitted parameter per ion species, for all energies and incident directions.…”