Review—Hybrid Bonding-Based Interconnects: A Status on the Last Robustness and Reliability Achievements

This paper reviews the most significant qualification and reliability achievements obtained, over the last 6 years, by the scientific community for hybrid bonding-based interconnects (HB) also named Cu–Cu or Cu/SiO₂ bonding. First, the definition of words qualification, robustness and reliability are given to avoid misunderstanding about the published results. Second, the five potential threats (moisture ingress, thermomechanical stresses, electromigration, Cu diffusion, dielectric breakdown) are presented. Finally, the publications of six industrials or Research and Technology Organizations are summarized and discussed. Most of the published data are related to qualification results (pass or fail). Few studies published in-depth studies, mainly on electromigration (Black’s parameters extraction and failure analysis) and copper diffusion (electrical and analytical characterizations). To conclude, once the manufacturing issues (surface preparation, alignment…) have been solved, this technology is robust and reliable at pitches > 1 μm as it reacts, roughly, like a conventional back-end of line (BEoL) interconnect.