Effect of microstructure on via extrusion profile and reliability implication for copper through-silicon vias (TSVs) structures

In this work, the effect of grain structure on TSV extrusion and its reliability implication are investigated through experimental measurements and modeling analysis. The grain orientation, elastic anisotropy and local plasticity are found to be important in controlling the extrusion profile which can directly impact the back-end-of-line (BEOL) reliability. Results from this study suggest that the Cu microstructure should be optimized from both global and local aspects in order to minimize the extrusion damage to the 3D structure.