Impact of passivation film deposition and post-annealing on the reliability of flash memories

This paper presents the impact of the passivation film deposition with various compositions and structures on the reliability of tunnel oxide in flash memories. The enhancement of the tunnel oxide degradation strongly depends on the refractive index of P-SiON passivation film. This result means that there is a correlation between the water resistibility of the passivation film and the tunnel oxide degradation induced by the passivation film deposition process. Moreover, the effect of post-annealing after passivation film deposition is discussed. The electron trap density is increased at the beginning and then decreased during post-annealing. The time constant of this phenomenon strongly depends on the refractive index of the passivation film. We propose the water-related electron trap model to explain the results.