Monte Carlo simulation of hyperthermal physical vapor deposition

Low-pressure sputtering and ionized vapor deposition processes create atomi c fluxes with kinetic energies in the 1.0-20 eV (and above) range. The impa ct energy of these hyperthermal atoms significantly effects the surface mor phology and structure of vapor deposited films. Recent molecular dynamics s imulations of metal atom interactions with a metal surface have established the energy and angular dependence of many of the impact energy induced mec hanisms of atomic assembly including biased diffusion, atomic reflection, r esputtering, and thermal transient induced "athermal" diffusion. These four effects have been incorporated into an earlier two-dimensional kinetic Mon te Carlo model that analyzes the thermally driven multipath diffusional pro cesses active during vapor deposition (Y. G. Yang et al., Acta Mater., 45 ( 1997) 1445). The contributions of the energy-dependent mechanisms to surfac e morphology were found to.-row in importance as the substrate temperature was reduced and/or as the rate of deposition increased. The simulation meth odology was used to establish functional dependence of surface roughness up on the atom's kinetic energy and its direction of incidence during the hype rthermal deposition of nickel vapor. The simulations reveal the existence o f a minimum surface roughness at an incident angle which increased with imp act atom kinetic energy. Modification of the impact energy is shown to be a viable means for controlling surface morphology during physical vapor depo sition under high deposition rate, low deposition temperature growth condit ions. (C) 2001 Published by Elsevier Science Ltd on behalf of Acta Material ia Inc.