Advances and Reliability Challenges in Heterogeneous Integration in Chiplet ERA: From Solder to Copper to Optical Interconnects

Advanced packaging is adopting more and more Cu-based interconnects in addition to conventional solder-based bumps, including micro-bumps (Cu pillars with solder caps), TSVs, Cu-Cu hybrid bonding, RDLs and Si bridges for lateral interconnects. Optical interconnects are also gaining traction. Heterogeneous integration of multiple chips into a package with these advanced interconnects and different materials poses difficult reliability challenges. This paper discusses the recent advances in the interconnect technologies with a focus on their reliability performance.