Cu self-sputtering MD simulations for 0.1–5 keV ions at elevated temperatures

Abstract

Self-sputtering of copper under high electric fields is considered to contribute to plasma buildup during a vacuum breakdown event frequently observed near metal surfaces, even in ultra high vacuum condition in different electric devices. In this study, by means of molecular dynamics simulations, we analyze the effect of surface temperature and morphology on the yield of self-sputtering of copper with ion energies of 0.1-5 keV. We analyze all three lowindex surfaces of Cu, {100}, {110} and {111}, held at different temperatures, 300 K, 500 K and 1200 K. The surface roughness relief is studied by either varying the angle of incidence on flat surfaces, or by using arbitrary roughened surfaces, which result in a more natural distribution of surface relief variations. Our simulations provide detailed characterization of copper self-sputtering with respect to different material temperatures, crystallographic orientations, surface roughness, energies, and angles of ion incidence.

Sputtering of surfaces by ion irradiation: A comparison of molecular dynamics and binary collision approximation models to laboratory measurements

“…for the polycrystalline, single crystal, and amorphous substrates, it appears that the crystal orientation has an insignificant influence on the sputtering yield for normal angles of incidence. This finding is supported by previous experimental 32 and MD studies 23 on both copper and other metals. In a future study, we plan to further investigate the important of crystallinity on sputtered atom energy and angular distribution.…”

“…To simulate the temperature dissipation found in a macroscale sample and to eliminate shock wave effects, two layers of atoms on the sidewalls and above the frozen bottom of the substrate were kept at room temperature using the Berendsen thermostat. 13,23,24 The remaining atoms were free to interact and increase in temperature via argon induced collisions.…”

“…Previous research has shown that channeling is insignificant for {100} FCC copper. 23 During each simulated impact, the region above the slab was scanned for emitted atoms. If sputtered atoms were observed, their atom types, locations, and velocities were recorded.…”

“…In all simulations, the interactions between atoms in the system were calculated using a hybrid interatomic potential. Cu-Cu interactions were simulated using an embedded atom method (EAM) interatomic potential originally developed by Mishin et al 25 This potential type has been previously used to describe sputtering yields of copper substrates at impact energies between 0.1 and 5 keV 23 and was originally parameterized to describe lattice, defect, and surface properties. Short distance interactions in EAM potentials are often obtained by extrapolation from equilibrium, but this renders them unreliable for the high energy repulsive forces observed during short distance interatomic separation.…”

Self-Sputtering of the Lennard-Jones Crystal

“…MD simulations have been widely used to study sputtering and deposition of Si-based materials [53][54][55][56][57][58][59][60][61][62][63][64] and metals. [65][66][67][68][69][70] Although physical phenomena of sputtering are highly complex and the exact sputtering yields may depend sensitively on the nature of atomic interactions of the system, it is also known empirically that the sputtering yield values can be approximately estimated with a relatively small number of physical characteristics of the system, e.g., the incident ion energy, incident ion mass, the atomic mass of the surface material, surface binding energy of the material, etc. 71 This suggests that relatively simple models of atomic interactions account for a large part of the sputtering phenomena involving those atoms.…”