Si0.85Ge0.15 oxynitridation in wet-nitric oxide ambient

Nitric oxide (NO) aided Si0.85Ge0.15 wet-oxynitridation has been performed at 400-700 °C, while the wet-NO feed gas was preheated to higher temperatures before entering the reaction zone. X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectroscopy data suggests that both nitrogen and oxygen incorporation increases within the dielectric bulk with increasing wet-oxynitridation temperature, while there is no apparent germanium segregation towards the dielectric/substrate interface at all temperatures studied. Moreover, angle-resolved XPS analysis suggests that wet-oxynitridation at temperatures higher than 600 °C volatilizes some germanium oxide from the surface region, while silicon monoxide is outgassed from the dielectric bulk and accumulates near the surface. Nitrogen incorporation is found to hinder germanium segregation. Z-contrast imaging with scanning transmission electron microscopy shows that oxynitrides grown in wet-NO have sharp interfaces with bulk Si0.85Ge0.15, while the roughness of the dielectric/Si0.85Ge0.15 substrate interface is less than 2 Å. These results are discussed in the context of an overall mechanism of SiGe wet-oxynitridation.