Reactive Sputtering of SiCN Films: Process Optimization and Bonding Behavior for Cu Hybrid Bonding

As semiconductor devices approach miniaturization limits, 3D packaging with hybrid bonding has emerged as a key solution. This study focuses on silicon carbon nitride (SiCN) films deposited by physical vapor deposition (PVD) as a cost-effective alternative to plasma-enhanced chemical vapor deposition (PECVD) for use as a low-k dielectric in Cu hybrid bonding. SiCN films were fabricated via reactive sputtering, with RF power and Ar/N₂ gas flow ratio varied systematically. Higher RF power and gas flow ratios led to increased carbon and nitrogen content and improved film density by about 10%, while surface roughness and contact angle remained stable. Despite a slight increase in dielectric constant with these parameters, values remained below 3.2, confirming low-k characteristics. Ar plasma surface pre-treatment without DI water rinse before bonding at 200 °C led to a carbon-rich interface and a thin SiOₓ layer, significantly improving bonding strength. A maximum shear strength of 15.8 MPa was achieved. The findings indicate that surface treatment plays a more crucial role in bonding quality than deposition conditions. This work demonstrates the potential of PVD-deposited SiCN as a reliable and cost-efficient dielectric material for advanced 3D integration using Cu hybrid bonding.