Accurate Lifetime Estimation of Sub-20-nm NAND Flash Memory

Previously, we developed a charge loss/gain model for NAND flash memory, which is taking into account various failure mechanisms. In addition, we extracted all the parameters of the new model in the highest (PV3) and lowest states (ERS). In this paper, however, the physical information for the parameters and the whole procedure of the parameter extraction are covered in detail. We also extracted the contribution rate (CR) of dominant mechanisms at the criterion of vertical bar Delta V-th_Total vertical bar according to the baking temperature. The results give the physical reason for abnormal retention behaviors such as apparent activation energy (E-aa) roll-off at the PV3 state and negative E-aa at the ERS state. Using the proposed method, we extracted the accurate lifetime at room temperature in all states (PV3, PV2, PV1, and ERS). A large gap was observed in the results of the lifetime estimation, which were extracted by the conventional Arrhenius model and the proposed model. Since the proposed model takes into account the retention characteristics for various mechanisms, this model provides a much more accurate prediction for the lifetime.