Interfacial properties of Cu-Cu direct bonds for TSV integration

We developed low-temperature, defect-free Cu-Cu direct bonding processes With high interfacial adhesion energies. The quantitative analyses of the interfacial adhesion energies and seam voids of Cu-Cu bonds performed with varying process parameters showed that bonding temperature and post-bond annealing have the most significant influence on bond properties. By optimizing experimental parameters, we could achieve, even with a short bonding time, sufficient interfacial adhesion energies (>= 5 J/m(2) for the subsequent processes such as grinding) with no interfacial seam voids. Post-bond annealing performed at 250-300 degrees C drastically improves the interfacial adhesion energy.