Nitrogen passivates SiO(2)-Si interface by creating interfacial Si=N bonds. While the same effect is observed in the case of SiC, there is a growing evidence that nitrogen plays an additional role at the SiO(2)-SiC interface, which relates to mole efficient removal of carbon from the interface. Indications for the existence of this effect evolved from earlier atomic-force microscope (AFM) and x-ray photoelectron spectroscopy (XPS) analyses. This paper adds new effects by comparing the rates of oxide growth in NO/N(2)O and the associated secondary-ion-mass-spectroscopy (SIMS) profiles of nitrogen for the cases of Si and SiC substrates. The assumption that the nitrogen is involved in carbon removal from the interface can explain the experimentally observed differences in both nitrogen concentrations at the interfaces and relative growth rates.