Interface Analysis of Direct Bonded Oxide Layers by Neutron Reflectometry

Fusion bonding is one of the great tools for wafer level 3D integrations: The surfaces such as SiO
2
are activated by plasma, then they are bonded to each other by hydrogen bonding, and are dehydrated by annealing to obtain a strong bond. It is now widely used for wafer-level bonding. On the other hand, it is known that the amount of water at the interface greatly affects the bonding properties before and after bonding. In this report, we have used neutron beams from the Japan Proton Accelerator Research Complex to investigate the effect of water vapor on the oxide film bonding interface, The penetration of water vapor into the oxide film bonding interface was evaluated by the neutron reflectometry.