Charge Storage Characteristics of Pi-Gate Poly-Si Nanowires TaN-Al₂O₃-Si₃N₄-SiO₂-Si Flash Memory

摘要

This work presents a novel TaN-Al2O3-Si3N4-SiO2-Silicon (TANOS) nonvolatile memory (NVM) witha structure that comprises Pi-gate (-gate) nanowires (NWs) structure. The Pi-gate structure in thisTANOS NVM increases on current (Ion), decreases the threshold voltage (Vth) and the subthresholdslope (SS), and enlarges the memory window (Vth). Furthermore, the use of high-k Al2O3 and a metalgate TaN structure enhances the program/erase efficiency and reliability. This NVM device has a highfast program/erase (P/E) speed; A 3 V memory window can be achieved by applying 18 V for only in10 s. With respect to endurance and high-temperature retention characteristics, the 70 % and 60 % of4 the initial memory window was maintained after 10 P/E-cycle stress, and ten years of data storage,respectively. Two-bit operation is achieved and retention characteristics are favorable because of thelocalized charge trapping in the nitride layer.