Cu-SiO2 Hybrid Bonding Yield Enhancement Through Cu Grain Enlargement

We have investigated the effect of an extremely large and relatively ordered Cu grains on the yield of Cu-Cu direct bonding/Cu-SiO2 hybrid bonding. Both modified electroplating method and the post processing have resulted into the formation of 10 – 15 μm large Cu grains before Cu-Cu direct bonding/CuSiO2 hybrid bonding. Employing such large and oriented grains, we have successfully carried out Cu-SiO2 hybrid bonding using 5 μm-size Cu electrodes at 10 μm-pitch values. The microstructural evaluation confirmed the formation relatively oriented Cu-grains. The more tensile nature of oriented Cu grains formed by modified electroplating and post processing might facilitate the Cu diffusion during the Cu-Cu direct/Cu-SiO2hybrid bonding.