In this paper, we have studied the charge trapping mechanisms of nitride-based non-volatile memories. The impact of different silicon-nitride (SiN) compositions (standard, std, and Si-rich) on the device characteristics has been investigated through material characterizations, electrical measurements, atomistic and electrical simulations. We found that the different physical nature of the dominant defects in the two SiN compositions is at the origin of the different device electrical behaviors. In particular, we argue that the different electron occupation number of the defect states of the two SiN materials explains the observed faster erasing speed and charge loss rate of Si-rich SiN devices, with respect to std SiN devices, in spite of comparable programming behavior. A simple trap model is proposed to improve state of the art simulators of SiN based memories.
