Prebonding Baking of Wafers for Improved Surface Activated Bonding

Surface activated bonding (SAB) is a room temperature wafer-level bonding technique widely used in the packaging and fabrication of electronic devices. The standard SAB process for Si involves the removal of surface oxides and contamination layers via fast atom bombardment, which generates dangling bonds on the outermost Si surface. However, adsorbed water on wafer surfaces hinders this activation process, leading to degraded bonding quality. In this study, we investigate prebonding baking as a method to eliminate adsorbed water before the SAB step. Experimental results demonstrate that pre-bonding baking significantly enhances bond strength for Si, sapphire, and SiO2 by effectively desorbing water from the wafer surfaces. Additionally, annealing Si wafers prior to SAB reduces residual oxides at the bonding interface, indicating improved activation efficiency. These findings highlight the potential of pre-bonding baking as an effective approach to enhance room-temperature wafer bonding quality using the SAB methodology.