Cu-SiO<sub>2</sub> Hybrid Bonding Yield Enhancement Through Cu Grain Enlargement
M. Murugesan, K. Mori, M. Sawa, Eli D. Sone, Mitsumasa Koyanagi, Takafumi Fukushima
Abstract
We have investigated the effect of an extremely large and relatively ordered Cu grains on the yield of Cu-Cu direct bonding/Cu-SiO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> 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/CuSiO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> hybrid bonding. Employing such large and oriented grains, we have successfully carried out Cu-SiO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> 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-SiO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> hybrid bonding.