Si 0.85 Ge 0.15 oxynitridation in nitric oxide/nitrous oxide ambient

Abstract

Low temperature, nitric oxide (NO)/nitrous oxide (N2O) aided, sub-35 Å Si0.85Ge0.15 oxynitrides have been grown at 550 and 650 °C, while the oxynitridation feed gases have been preheated to 900 and 1000 °C, respectively, before entering the reaction zone. X-ray photoelectron spectroscopy and secondary ion mass spectroscopy (SIMS) data suggest that NO-assisted oxynitridation incorporates more nitrogen than the N2O-assisted one, while there is minimal Ge segregation towards the dielectric/substrate interface in both oxynitridation processes. Moreover, SIMS results suggest that nitrogen is distributed throughout the film in contrast to high temperature Si oxynitridation, where nitrogen incorporation takes place near the dielectric/substrate interface. Z-contrast imaging with scanning transmission electron microscopy shows that the oxynitride grown in NO at 650 °C has a sharp interface with the 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 oxynitridation.