Anomalous Electron Storage Decrease in MONOS´ Nitride Layers Thinner Than 4 nm

An anomalous decrease in electron-storage capability of metal-oxide-nitride-oxide-silicon (MONOS) was observed in the range of nitride thickness below 4 nm. This decrease can be explained by assuming transition layers with electron traps at oxide/nitride interfaces or inhomogeneous growth of nitride in the early stage of the growth. To decrease the nitride thickness of a MONOS memory below 4 nm for lower power operation and further device scaling down, transition layer should be thinned, or nitride roughness should be reduced.