Impact of Cu Pad Density on Cu-CMP and Bonding Yield for Chip-to-Wafer Hybrid Bonding

The role of metal density around fiducial marks (used for chip alignment) on the quality of chemical-mechanical-planarization (CMP) of Cu bond-pads/electrodes has been meticulously studied via two different layout designs. A gradual increase in the metal density between the fiducial mark and the Cu bond-pads/electrodes region has resulted in improved Cu- CMP quality. We have successfully minimized the dishing amount as well as the erosion quantity of Cu bond-pads/electrodes through optimized metal density, which are highly important to realize the high-quality and high-yield chip-to-wafer hybrid bonding.