Comparative study on nanocrystal embedded gate dielectric and oxide nitride oxide stack dielectric GAA MOSFET non-volatile memory devices

Abstract

Gate All Around (GAA) MOSFET Non Volatile Memories (NVMs) are a recent topic of research. Such devices usually employ the conventional Si-Oxide-Nitride-Si (SONOS) stacks for charge storage. However, embedding nanocrystals (nc) in the gate dielectric could be highly useful in improving charge storage and suppressing charge leakage in such GAA memories. In this work, we compare the performance of the nc Au embedded SiO 2 -HfO 2 stacked gate dielectric GAA NVM with an Oxide-Nitride-Oxide (ONO) stack GAA NVM device of similar dimensions. Using a pseudo 2D based method, we evaluate the surface potential of the GAA MOS. Applying the Gauss' law the fields in the different layers in the gate dielectric stacks of the GAA MOS device was evaluated. Thereafter using a Wentzel-Kramers-Brillouin (WKB) approximation based model, we compute the Fowler-Nordheim tunneling currents in a GAA MOSFET NVM. We simulated the Ig-Vg characteristic, flatband shifts and memory window, and the direct tunneling leakage in such devices.