Origin of Voids at the SiO₂/SiO₂ and SiCN/SiCN Bonding Interface Using Positron Annihilation Spectroscopy and Electron Spin Resonance

To obtain reliable 3D stacking, a void-free bonding interface should be obtained during wafer-to-wafer direct bonding. Historically, SiO 2 is the most studied dielectric layer for applications, and it reported to form voids at interface. Recently, SiCN has raised as new candidate layer. Further understanding of mechanism behind void formation would allow avoid on different dielectrics. In this study, was wafer pair deposited by plasma enhanced chemical vapor deposition (PECVD). The presence confirmed after post-bond anneal (PBA) 350 °C Scanning Acoustic Microscopy. Alternatively, PECVD demonstrated post bond annealing. better understand interface, we used Positron Annihilation Spectroscopy (PAS) inspect atomic-level open spaces Electron Spin Resonance (ESR) evaluate dangling N activation. By correlating these results with previous results, model absence proposed.