Room temperature direct bonding of Si wafers smoothed by Ne beam irradiation

We found the improvement of the bonding strength by surface smoothing effect of Ne fast-atom-beam (FAB). Surface roughness of a Si wafer decreased from 0.40 to 0.17 nm rms by applying the Ne FAB etching of 30 nm depth. The bonding strength was largely improved by Ne FAB surface smoothing and finally became equivalent to Si bulk strength.