Room temperature wafer direct bonding of smooth Si surfaces recovered by Ne beam surface treatments

Abstract

We examined the applicability of a Ne fast atom beam (FAB) to surface activated bonding of Si wafers at room temperature. With etching depth more than 1.5 nm, the bonding strength comparable to Si bulk strength was attained. Moreover, we found the improvement of the bonding strength by surface smoothing effect of the Ne FAB. Silicon surface roughness decreased from 0.40 to 0.17 nm rms by applying a Ne FAB of 30 nm etching depth. The bonding strength between surfaces recovered by Ne FAB surface smoothing was largely improved and finally became equivalent to Si bulk strength.