Influence of substrate dc bias on chemical bonding, adhesion and roughness of carbon nitride films

Abstract

Carbon nitride (CNx) films had been grown on Si (001) substrates using rf magnetron sputtering method in pure N2 as substrate bias (Vb) was varied from 0V to −150V and substrate temperature (Ts) kept at a constant of 350°C. The chemical bonding states of CNx films were characterized using Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). It was observed that a predominant formation of sp3 CN bonds occurred in carbon nitride films grown at bias of −50V. The scratch test was utilized for measurement of CNx coating adhesion on Si (001), and then the morphology of the films was analyzed using atomic force microscopy (AFM) experiments. The results revealed that CNx films grown at Vb=−100V, having the smoothest surface with the lowest rms roughness of 0.75nm, adhered much more strongly to the Si (001) substrate than at other substrate bias values. Furthermore, the effect of ion bombarding on the adhesion and roughness of CNx films on Si (001) was discussed.