Investigation of Ar incident energy and Ar incident angle effects on surface roughness of Cu metallic thin film in ion assisted deposition

This paper employs molecular dynamics (MD) simulations to investigate the influence of the Ar ion incident energy and incident angle on the surface roughness of Cu films fabricated using the ion assisted deposition (IAD) process. The MD simulations use the tight-binding potential and the Molière potential to simulate the Cu-Cu and Cu-Ar+ interactions, respectively. The numerical results indicate that the dependency of the surface roughness on the incident angle of the ions is a function of the ion incident energy. At lower incident energies, a weaker dependency exists, and the surface roughness is improved irrespective of the ion incident angle. However, at intermediate and higher ion incident energies, the dependency of the surface roughness on the incident angle becomes more apparent. Under these conditions, a higher incident angle yields an improved surface roughness. Increasing the ion assisted ratio has a similar effect on the surface roughness as increasing the ion incident energy. The results indicate that an excessive ion assisted ratio leads to the formation of a rougher surface; particularly at higher ion incident energies.