ON THE IDENTIFICATION OF N DANGLING BONDS IN SIN FILMS USING X-RAY ABSORPTION STUDIES

Thin amorphous Si3N4 films grown on Si are studied with the near-edge x-ray absorption fine structure (NEXAFS) characterization technique. The N dangling bonds in N-rich films give rise to a strong resonance line (RL) at the onset of the N 1s absorption edge, with an intensity that increases with the N/Si ratio. Further evidence on the origin of the RL is provided by the NEXAFS spectra from nitrogen-implanted Si and Si3N4 films bombarded with Ar+ ions. The RL can be annealed out after annealing at temperatures higher than the growth temperature. We propose that the annealing of the RL is due to formation of Si-N bonds, where the Si atoms are provided by the stressed interface. The velocity of the annealing process is controlled by the diffusivity of Si interstitials in the Si3N4 and the process is characterized by an activation energy of 0.86 eV.