NrGO Floating Gate/SiOXNY Tunneling Layer Stack for Nonvolatile Flash Memory Applications

Abstract

This paper presents an ultra–thin silicon oxynitride (SiOXNY, 4 nm) tunneling layer, nitrogen functionalized reduced graphene oxide (NrGO, 3–5 layer) floating gate (FG) and poly (methyl methacrylate) (PMMA, 60 nm) blocking layers based Al/PMMA/NrGO/SiOXNY/p–Si/Au, non–volatile flash memory (NVFM) structures. The ultra–thin SiOXNYhelps in improving the interface with Si, resulting in lower gate leakage current density and considerable enhanced retention characteristics. The nitrogen engineered GO followed by reduction to NrGO under UV illumination attributes to the modification of the physiochemical properties, hence beneficial for non-volatile memory applications. The uniform, stress free and low temperature processing advocates the potential of PMMA as blocking layer for improved memory characteristics. The electrical characterizations on the fabricated Al/PMMA/NrGO/SiOXNY/p–Si/Au gate stack demonstrates a memory window ( ${\delta }\text{W}$ ) of ~1.25 V @ ± 3 V and ~2.6 V @ ± 5 V, low gate leakage current density (J) ~10 nA/cm2@ −1 V, retention $\sim 3 \times 10^{11}$ sec (> 10 years with extrapolation) and endurance of more than 100 cycles.