Optimization of Ag Thin Film Thickness with a Capping Layer for Ag-Ag Surface Activated Bonding

In this work, we tried to fabricate a smooth Ag surface by reducing the thickness of Ag layer from 30 nm to 10 nm. The thickness of Ti capping layer was 2 nm and Ti adhesion layer has thickness with 5 nm. The results shows that the surface roughness of Ag thin film with Ti capping layer is smaller than Ag thin film without Ti capping layer for both thickness of Ag thin film. Furthermore, surface roughness (Sa)was reduced from about 0.7 nm to 0.35 nm by reducing the thickness of the Ag thin films from 30 nm to 10 nm, when the Ti capping layer was used.