Low energy sputtering of nickel by normally incident xenon ions

Abstract

New sputter deposition processes, such as biased target ion beam deposition, are beginning to be used to grow metallic superlattices. In these processes, sputtering of a target material at ion energies close to the threshold for the onset of sputtering can be used to create a low energy flux of metal atoms and reflected neutrals. Using embedded atom method potentials for fcc metals and a universal potential to describe metal interactions with the inert gas atoms used for sputtering, we have used molecular dynamics simulations to investigate the fundamental phenomena controlling the emitted vapor atom and reflected neutral fluxes in the low energy sputtering regime. Detailed simulations of low energy, normally incident Xe + ion sputtering of low index nickel surfaces are reported. The sputtering yield, energy and angular distributions of sputtered atoms, together with the reflection probability, energy and angular distributions of reflected neutrals were deduced and compared with available experimental data. The average energy of sputtered metal atoms can be controllably reduced to 1–2 eV as the Xe + ion energy is reduced to 50–100 eV. Normally incident Xe + ion sputtering in this energy range results in reflected Xe energies that are narrowly distributed between 2 eV and 6 eV. These fluxes are ideally suited for the growth of metallic multilayers.