The Scaling of Cu-Cu Hybrid Bonding For High Density 3D Chip Stacking

We have successfully improved the scaling of Cu-Cu hybrid bonding. In this study, 3 $\mu {\mathrm{ m}}$-pitch and 3M Cu-Cu connections with sufficient electrical properties and reliabilities were achieved. The ultra-fine pitch Cu-Cu connections correspond to the 0.75x scaling of conventional Cu-Cu hybrid bonding that we previously reported. Our high density 3D chip stacking technology is expected to enhance not only the function of back-illuminated CMOS image sensors (BI-CIS) but also that of coming 3D stacked semiconductor devices.