Variability and disturb sources in ferroelectric 3D NANDs and comparison to Charge-Trap equivalents

We investigate physical mechanisms driving the retention and disturb of charge-trap (CT) based and ferroelectric-(FE) based 3D NAND string. Combining a calibrated CT 3D NAND model and calibrated material properties of the FE material (extracted from FE-FinFET), we extrapolate and compare the existing workhorse with the low-power, high-speed contender. We show that: (1) a inherently discretized FE-stabilization combined with the polycrystalline nature of HZO, and interface charge compensation guarantees MLC capability; (2) FE 3D NAND offers higher ON currents that enable further Z-scaling. Furthermore, we develop a retention model and show that independently of the inherited discretization of the storage layer, lateral charge migration (of the parasitically trapped charge that stabilizes polarization) combined with pass voltage (disturb) can cause retention loss of FE 3D NAND. Finally, integration (layer-cut) and material engineering approaches are suggested for mitigation and guaranteeing stable operation of the string.