Chip-to-Chip Hybrid Bonding with Larger-Oriented Cu Grains for µ-joints Beyond 100 K
M. Murugesan, M. Sawa, Eli D. Sone, T. Miyazaki, Mitsumasa Koyanagi, Takafumi Fukushima
Abstract
The role of enlarged and relatively oriented Cu grains on Cu-SiO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> hybrid bonding at chip level has been investigated. Larger Cu-grains in the Cu-Cu µ-joints were obtained by the modifying Cu electroplating chemistry. We were able to bring down the resistance of 5 µm square-size Cu-Cu µ-joints in as tight as 8 µm pitched intervals. The measured resistance of the single Cu-Cu µ-joint was around 5 mΩ and 8 mΩ, respectively for Cu electrodes with larger and normal Cu-grains. Thus, we were able to realize more than 30% reduction in the resistance value for the Cu µ-joints with larger Cu-grains. The lower resistance was attributed to the better interface quality of the Cu-Cu µ-joints facilitated by these enlarged and relatively oriented Cu-grains.