Lattice optimization of Si-Cu interfaces on the atomic scale

Molecular dynamics is used to simulate a thin copper coated silicon film. To increase the understanding in design optimization of copper coated silicon structures, the two crystals that the film consists of are oriented in 17 different lattice orientation combinations and a shear load is applied on the top of the copper coating while the bottom of the silicon base is fixed. The force-displacement and centrosymmetry-displacement relations are studied and a correlation between these two is shown. The results show that, near the interface, the lattice orientations affect the atom arrangement and the atom movements. This has a large impact on the mechanical properties such as the stiffness, the shear resistance and the maximum load. Furthermore, the results show that some lattice orientation combinations have an initial stiffness that is more than four times larger than the initial stiffnesses of other lattice orientation combinations. Also, the ability to absorb strain energy varies largely between cases.