Charge loss behavior of manos-type flash memory cell with different levels of charge injection

In this study, we found that the charge loss behavior of MANOS device for NAND Flash memory application is highly dependent on the amount of injected charges (defined as Q_inj (=C_oxtimesDeltaV_FB)). Beyond the critical amount of Q_inj (defined as Q_c), the direction of dominant charge loss path changes from SiO₂ towards Al₂O₃. This result was verified by experimental and simulation results through the comparison between ONO and ONA stacks. For detailed analyses, we investigated the impact of blocking oxide thickness and retention temperature. For further understanding, we performed long-term retention measurements up to ~10⁶ s at different level of Q_inj to investigate the correlation between the energy trap level (E_TA) and Q_inj.