Recent Advances on Electromigration in Cu/SiO2 to Cu/SiO2 Hybrid Bonds for 3D Integrated Circuits

With hybrid bonding (HB) pitch reduction, many challenges are arising. One of them is related to the reliability of HB-based interconnects and in particular their electromigration performances as electromigration (EM)-related degradation is intimately linked to the electrical current in addition to temperature and mechanical stresses. This study highlights a change in the failure modes for EM-related failures in HB-based interconnects when decreasing the interconnect pitch from 6.84 down to 1.44 µm. The weakest link moves from the BEOL levels to hybrid bonding ones but without affecting the projected performance under use conditions. Additional studies done on design aspects do not evidence any negative impact on the electro migration resistance of the HB brick.