Robust spin-on glass gap-fill process technology for sub-30nm interlayer dielectrics

A highly robust gap-fill process technology of spin-on glass (SOG) was developed for the interlayer dielectric (ILD) in sub-30 nm devices. We revealed that the filling behavior of SOG within gaps during spin-coating is mainly dependent on the capillary effect. The highly wettable surface treatment prior to SOG coating was found to enhance the gap-fill performance remarkably. This technique plays a key role in maximizing capillary effect by raising surface wettability. The filling capability was also improved by optimization of baking temperature to minimize the viscosity of SOG. It was finally found that the defects of contact bridges due to poor filling of SOG were reduced to be almost free by those unique process refinements.