Investigation of the light-induced effects in nitrogen-rich silicon nitride films

We report the first observations of photoconductivity fatigue and generation of positive fixed charges under ultraviolet illumination in gate-quality nitrogen-rich silicon nitride films, using metal-nitride-silicon and metal-nitride-oxide-silicon structures. The photoconductivity fatigue is correlated with the density of neutral silicon dangling bonds measured by electron spin resonance. Spins and positive fixed charges are generated at the same time, but a different rates and in a different amount. Possible models are discussed to explain the observed results.