Precise understanding of data retention mechanisms for MONOS memories: Toward simultaneous improvement of retention and endurance performances by SiN engineering

We investigate the charge leakage path during data retention through the evaluation of its temperature dependence. As a result, it is experimentally demonstrated for the first time that the main leakage path of trapped charge changes depending on retention time. Furthermore, the direction of leakage path rather than trap energy profile in the SiN layer determines the temperature dependence of data retention characteristics. In addition, it is found that cycling degradation of data retention is due to increase in the charge loss through the tunnel layer. Based on the accurate understanding of data retention mechanisms, we show the possibility to achieve both of data retention and endurance improvements by SiN engineering.