The Challenges and Solutions of Cu/SiCN Wafer-to-Wafer Hybrid Bonding Scaling Down to 400nm Pitch

This paper presents an investigation into the scaling of wafer-to-wafer (W2W) hybrid bonding (HB) technology for the manufacture of advanced electronic devices. However, the scaling of W2W bonding has been challenging due to limitations in bond strength and alignment accuracy. In this study, we review the current state of W2W bonding technology and discuss recent breakthroughs that have enabled significant scaling. We propose a test vehicle design using a hexagonal grid with circular pads to overcome bonding overlay control challenges. We also explore the selection of SiCN as the bonding dielectric and demonstrate high bonding energy and controlled Cu bulge out. The results show successful control of Cu/SiCN surface topography, precise alignment accuracy, and favorable electrical performance. Additionally, we analyze the relationship between bonding overlay and single contact resistance, yield performance, and reliability. Our findings provide valuable insights into the advancements and significance of W2W bonding scaling.