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

In order to investigate the effects of substrates, amorphous carbon nitride thin films were deposited onto crystalline silicon and amorphous silicon nitride (a-SiN_x) 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-SiN_x 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 angstroms thickness. The characteristics of growing process of carbon nitride films on a-SiN_x are similar to those of carbon nitride films on silicon. But the absolute values of the former properties, such as sp³/sp² ratio and I_D/I_G 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.