Atomistic modeling of physical vapor deposition on complex topology substrates

Molecular Dynamics simulations of Cu physical vapor deposition are employed to investigate the effects of substrate topology and line of sight on the synthesis of thin films on Cu substrates. The deposition and surface relaxation processes of sputtering Cu ions are simulated considering various angles of incidence (0-60 degrees) and sputtering energies (1, 10, 25, and 50 eV). Cu substrates are constructed with three different surface geometries: i) a flat Cu (1 1 1) surface; ii) a sinusoidal shaped substrate with a period of 127.6 angstrom and amplitude 20 angstrom ; and iii) a combined substrate composed of a flat Cu (1 11) surface and a cylinder of radius 63.8 angstrom, floating 50 angstrom above the flat surface. Results from simulations with low impact energy (1 eV) show a strong effect of the angle of incidence on the roughness of the thin film produced on the flat surface. For non-flat substrates, areas with no line of sight have diminished film coverage, which is offset by increasing the deposition energy. Higher energy atoms have greater adatom mobility enabling the coverage of regions with no line of sight and the reduction of surface roughness. The results show a lower sticking probability for highly energetic deposition at high angles of deposition, effectively promoting film coverage in areas with no line of sight through physical redeposition processes, which is augmented by particle-induced sputtering. These atomistic insights are relevant for the understanding of physical vapor deposition processes on convoluted topology substrates, such as magnetron sputtering on metamaterial lattices.

Automated summary

The research found that non-flat areas on copper substrates have lower film coverage, but this can be offset by increasing deposition energy. Higher energy atoms are able to increase adatom mobility to cover line-of-sight regions and reduce surface roughness.