Combined Surface-Activated Bonding (SAB) Technologies for New Approach to Low Temperature Wafer Bonding

Wafer surface activation is of great importance for low temperature wafer bonding process development. However, different surface activation methods are needed for various bonding materials due to their different requirements and mechanisms for low temperature bonding. A challenge of the low temperature wafer bonding technology is to develop compatible surface activation processes for hybrid surfaces (e.g., Cu/polymer adhesive and Cu/SiO2 hybrid surfaces). In this study, we developed surface activation processes for low temperature Cu/dielectric hybrid bonding. We report the results of surface treatment for Cu/adhesive hybrid surface by using Ar plasma and Ar fast atom bombardment, and a combined SAB process for SiO2 hydrophilic bonding. Post-bonding vacuum annealing is employed to develop void-free hydrophilic SiO2 wafer bonding.