Improvements of Performance and Reliability for Metal–Oxide–Nitride–Oxide–Silicon Flash Memory With NO- or N2O-Grown Oxynitride as Tunnel Layer

Abstract

The characteristics of oxynitride thermally grown in either NO or N 2 O ambient as a tunnel layer are investigated based on an Al/Al 2 O 3 /GdON/SiO x N y /Si structure. The physical thickness of each dielectric layer was measured and confirmed by multiwavelength ellipsometry and transmission electron microscopy. Experimental results reveal that better memory performances can be achieved for the metal-oxide-nitride-oxide-silicon (MONOS) device with NO-grown oxynitride as the tunnel layer, e.g., larger memory window, higher program/erase speed, better endurance, and retention characteristics, compared with devices with N 2 O -grown oxynitride and conventional SiO 2 as the tunnel layer. The involved mechanisms lie in NO-nitridation-induced smaller hole barrier height, formation of more strong Si-N bonds at/near the oxynitride/Si interface due to more nitrogen incorporation in the tunnel layer. Therefore, the application of NO-grown oxynitride as tunnel layer is promising in advanced MONOS nonvolatile memory devices.