Formation of Ultrathin SiON Films on Si Substrates Having Different Orientations

We investigated the formation of ~1–3 nm ultrathin SiON films by the plasma nitridation of oxidized Si substrates having different orientations, namely, (100), (110), and (111). Oxidation was performed by dry, wet, and plasma oxidation processes with rapid thermal oxidation (RTO), in situ steam generation (ISSG), and a slot plane antenna (SPA), respectively. Nitridation was performed by a plasma nitridation process with SPA. The thickness of base SiO2 films prepared by a plasma oxide process was independent of substrate orientation unlike in the dry and wet oxidation processes. Furthermore, no significant discrepancy in nitrogen areal density was observed among the SiON films grown by the plasma nitridation of differently oriented oxidized Si substrates. Our results suggest that SiON films with arbitrary nitrogen densities and thicknesses can be prepared by oxidation and plasma nitridation irrespective of the Si substrate orientation.