Advances in SiCN-SiCN Bonding with High Accuracy Wafer-to-Wafer (W2W) Stacking Technology

Results are presented of recent studies in material exploration for W2W bonding and advanced W2W alignment carried out as a holistic approach to enable a robust ultra-fine pitch interconnect for 3Dsystem-on-chip (SoC) technology. Various characterization methods have been employed, including electron-spin-resonance (ESR) monitoring of dangling-bond-type defects, invoked to compare SiCN-SiCN and SiO ₂ -SiO ₂ bonding bonding strength in terms of the the evolution of chemical bond densities at the interface. Furthermore, sub-200 nm W2W overlay performance has been demonstrated to cope with 3D interconnect scaling and stringent contact requirements. State-of-the-art overlay performance is achieved by the enabling features of the W2W aligner while the incoming wafer characteristics are monitored. The study provides a positive outlook to 3D SoC technological realization and sub-μm pitch scaling solutions.