Research Progress on the Surface/Interface Reaction Mechanism of Metal/Dielectric Heterogeneous Materials in Hybrid Bonding

Advanced packaging has attached great attention with the rising demand for processor performance and the approaching physical limit of transistor size. Hybrid bonding technology stands out as one of the mainstream technologies for next-generation 3D packaging due to the small interconnect pitch and high bandwidth. The main process flow includes chemical mechanical polishing (CMP), surface activation, room-temperature pre-bonding, and annealing. However, due to the complex material system and long processing flow, the reaction mechanism at the bonding surface and interface remains unclear, which is closely related to the bonding process and interface quality. This paper systematically reviews the physicochemical reaction and the mechanism of metal/dielectric heterogeneous materials in the hybrid bonding process. Including (1) the influence of plasma and chemical treatment on the composition and structure of the metal/dielectric surface; (2) the evolution of the interfacial force, the influence of water molecules and bonding wave; (3) the bonding mechanism of metal/dielectric and the side reaction related to reliability. The comprehensive review of the surface and interface reaction helps to understand the bonding mechanism, which will guide the development of hybrid bonding technology.