Effect of C_xN_y Molecular Species on Carbon Nitride Thin Films Deposited by Radio Frequency Magnetron Sputtering

Abstract

Carbon nitride films were deposited on Si(100) substrates by radio frequency (RF) magnetron sputtering at different working pressures and gas ratios. The effect of the gas pressure on the molecular structure of the carbon nitride films and CxNy molecular behavior has been discussed. A quadrupole mass spectrometer (QMS) was fitted with a chamber to investigate CxNy molecular species in the gas phase. The composition and bonding were analyzed by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). An increase in film growth rate was observed with increasing working pressure and nitrogen proportion in the sputtering gas. However, the film growth rate decreased when the working pressures were over ∼10 mTorr. The N/C ratios in the CNx film were in the range of 0.52–0.67 and increased with working pressure. The XPS and FTIR spectra confirmed that a decrease in working pressure resulted in an increase in the number of sp3 C–N bonds. It may be concluded that the decrease in C2N molecules containing a high proportion of carbon and the increase in CN2 containing a high proportion of nitrogen due to the increase in working pressure affected N incorporation in the films.