TID Radiation Impacts on Charge-trapping Macaroni 3D NAND Flash Memory

The total ionizing dose (TID) impacts are studied in charge-trapping (CT) type 3D NAND flash memories with a MONOS (metal-oxide-nitride-oxide-silicon) cell structure and macaroni core oxide. By 3D TCAD simulations, higher leakage currents (I
_off
) and lower threshold voltage (V
_th
) can be observed when the irradiation impacts at the core oxide layer are taken into account. In addition, it is also found that TID has ignorable impacts on the cells when the irradiation occurs at the space oxide region. Thus, though the macaroni 3D NAND structure with a core-oxide benefits the performance, it will make 3D NAND suffer from serious TID impacts and its applications in harsh environments will be limited. Our results are important for future development of CT flash memories aiming at robust reliabilities.