Shear anisotropy in Si-Cu interfaces on the atomic scale


Three dimensional molecular dynamics (MD) is used to model the mechanical response at the interface between a thin Cu coating resting on a base of Si. The copper coating is subjected to a displacement controlled shear load and the atom movements at the Si-Cu interface are monitored to investigate the effects of crystallographic anisotropy. The two crystals have the same crystallographic orientation, and two different interface normal directions are considered. The shear load is applied along different crystallographic directions to highlight the importance of crystallographic orientation for the mechanical response. The simulations are performed with the 3D MD free-ware LAMMPS. As the imposed displacement reaches a high enough magnitude, the Cu coating starts to slide over the Si base. Thus the atoms at the interface rearrange depending on loading direction and crystallographic orientation.