Low-Temperature Ru–Ru Hybrid Bonding: Ar/H 2 Plasma and NH 4 OH Synergistic Activation for Ultrahigh Density Interconnection

functional groups on the Ru surface, promoting interfacial reactions and the formation of a void-free interface. Intriguingly, the bond strengths exceeded 12 MPa after 1000 thermal cycles between -45 °C and +125 °C. This synergistic activation route provides a viable pathway for low-temperature Ru/dielectric hybrid bonding with high reliability. The demonstrated bonding performance underscores Ru potential as a Cu replacement in BEOL interconnects and establishes a foundation for metal/dielectric hybrid bonding in forthcoming high-density integration technologies.