Effect of thermal annealing on reactive radio-frequency magnetron-sputtered carbon nitride films

Carbon nitride (CN) thin films were deposited on Si(111) substrates by reactive radio-frequency magnetron sputtering. The effect of thermal annealing on the structural properties of the films has been studied by Fourier-transform infrared spectroscopy (FTIR) and x-ray photoelectron spectroscopy (XPS). Both FTIR and XPS results show that the amount of the carbon nitrogen phase decreases upon annealing and that it is eliminated by annealing at 900°C. Increasing the annealing temperature leads to the formation of a more prominent peak corresponding to the tetrahedral CN bonds in the FTIR absorption spectra. XPS N 1s peaks indicate that the third component due to the carbon nitrogen bonding state is significantly weaker than the others, relatively speaking. These results reveal that annealing causes a substantial decrease in the number of weakly bound nitrogen and carbon dangling bonds. The sp³ C-N phase is stable with respect to thermal treatment at 900°C.