The effects of substrates on carbon nitride thin films prepared by direct dual ion beam deposition

Abstract

In order to investigate the effects of substrates, amorphous carbon nitride thin films were deposited onto crystalline silicon and amorphous silicon nitride (a-SiNx) substrates using negative-carbon-ion beam and positive-nitrogen-ion beam. The resulting films were characterized using AES, XPS, Raman, and HRTEM. AES C KLL, Si LVV spectra and the result of cross-sectional HRTEM show that SiC was formed only on Si substrate as an intermediate phase, whereas carbon nitride films were formed directly on a-SiNx substrate without SiC intermediate phase. The deconvoluted results of XPS and Raman spectra show that the sp3/sp2 ratio and the atomic density of carbon nitride thin films increase with the deposition thickness except for the buffer layer corresponding to about 500 Å thickness. The characteristics of growing process of carbon nitride films on a-SiNx are similar to those of carbon nitride films on silicon. But the absolute values of the former properties, such as sp3/sp2 ratio and ID/IG ratio, are higher than those of the latter properties are. From these results, the different growth behavior of carbon nitride films on theses two substrates can be explained using the binding energy of each element.