Computer simulation of sticking and penetration of copper atoms on copper substrates

Abstract

The multiple interaction (MI) codes SPUT1 and SPUT2 have been used to investigate, the penetration of copper substrates by copper atoms with energies between 1 and 1000 eV. Initial simulations were carried out on ideal, single crystal targets ((100) face) that were 4–6 atomic layers thick. Below 10 eV essentially all normally incident copper atoms stuck to the crystallite surface, but did not penetrate the surface layer. From 10 eV up the normally incident ions buried themselves within the crystallite, and (from 50 eV up) caused sputtering of target atoms. Four target layers were sufficient to stop most incident ions with energies up to 500 eV. Additional target layers were needed to stop more energetic incident atoms. Stopping profiles and sputtering yields are presented as a function of energy. Some additional simulations were carried out with (111) and (110) single crystal targets to determine the effect of packing on penetration and sticking. Simulations also were carried out at 1 eV incident energy on partially covered targets to determine the effect of surface irregularities on sticking and penetration. Complete sticking was observed for these partially covered targets.