Structural relaxation of sputtered amorphous carbon nitride films during thermal annealing

A study of the stress relaxation caused by post-deposition thermal annealing of carbon nitride thin films (CNx) deposited onto Si substrates has been carried out. The intrinsic stress values were correlated with Fourier transform spectrometer (FTIR) and thermal desorption mass spectroscopy (TDMS) results. FTIR spectra showed the existence of N–Csp3, NCsp2 and C≡N triple bonds in the deposited films and indicates the occurrence of their porous character. The analysis of the spectra versus annealing temperature (TA) reveals two rearrangement mechanisms of the microstructure. Up to 200 °C, the reversion of NCsp2 to N–Csp3 and CCsp2 respectively, and then an increase of the connectivity of the C–C network for higher TA. These dissociation/recombination mechanisms are used to describe the stress release occurring within the (CNx) films upon heating.