Electrically neutral nitrogen dangling-bond defects in amorphous hydrogenated silicon nitride thin films

We have investigated the effects of different post-deposition temperature anneals and N-H concentrations, on the generation of ultraviolet (UV)-induced two-coordinated nitrogen dangling bonds in plasma-enhanced chemical vapor deposited (PECVD) silicon nitride films using electron spin resonance (ESR). It is shown that the nitrogen dangling bond is activated by post-deposition anneals with temperatures as low as 500°C in N-rich PECVD nitride films followed by subsequent UV broadband illumination. It also appears that there is a possible correlation between the initial N-H concentration in the films and the concentration of generated nitrogen dangling bonds following the anneal/UV sequence. We also report the charge state associated with the nitrogen dangling bond using a combination of ESR and capacitance versus voltage measurements; these measurements suggest that this two-coordinated defect is electrically neutral when paramagnetic.