Effect of control oxide thickness on a stepped NFGM for multi-bit application

In this work, dependence of storage characteristics of nano-floating gate memory (NFGM) on the control oxide thickness was evaluated in a single stepped NFGM. A stepped NFGM enables the multi-bit storage characteristics through two distinguishable charge trapping voltages due to the different control oxide thickness under the electrode. Based on the simulation results, we fabricated a stepped NFGM with 20/40 nm stepped HfO2 control oxide covering Au nanocrystals on 5nm thick thermally grown SiO2 tunneling oxide. We could successfully demonstrate the multi-level charge trapping behavior that agrees with the simulation prediction in a single stepped NFGM.