A comparative study of interatomic potentials for copper and aluminum gas phase sputter atom transport simulations

A comparative study of interatomic potential models for use in gas phase sputter atom transport simulations is presented. Quantum chemical interatomic potentials for argon-copper and argon-aluminum are calculated using Kohn-Sham density functional theory utilizing the PW91 functional. These potentials (PW91) are compared to the commonly used Born-Mayer potentials calculated by Abrahamson [Phys. Rev. 178 (1969) 76] using the Thomas-Fermi-Dirac model (TFD) and the screened Coulomb potentials derived from the 'universal' form calculated by Ziegler, Biersack and Littmark (ZBL). Monte Carlo simulations of gas phase sputter atom transport were performed to determine the average energy of atoms arriving at the substrate versus pressure for the three potential models. Overall, the ZBL potential gave results in much better agreement with the PW91 potential than the TFD potential. A characteristic thermalization pressure-distance product of ∼0.11 mTorr cm was found for both copper and aluminum using the PW91 potential