Study of Intercell Trapped Charge for Data Retention Improvement in 3D NAND Flash Memory

In this work, TCAD simulation was adopted to investigate the influence of intercell trapped charge on data retention properties of 3D NAND. The simulation structure of MONOS and proper physical models were introduced to emulate the electric field distribution and physical characteristics in a real device. Under this circumstance, different even/odd erase methods were adopted to introduce intercell electrons in charge trap layer. According to TCAD simulation results, the intercell trapped charge induced by a novel even/odd erase mode is promising to improve data retention. Besides, state dependence was also investigated. It was found that higher state shows larger data retention improvement. This study demonstrated an effective method for data retention improvement and provided theoretical explanation for corresponding results.