HfN multi charge trapping layers for Hf-based metal-oxide-nitride-oxide-Si nonvolatile memory

The effect of HfN multi charge trapping layers (CTLs) on the Hf-based metal/oxide/nitride/oxide/Si (MONOS) nonvolatile memory characteristics was investigated to improve the threshold voltage (VTH) controllability. The Hf-based MONOS structure with HfN1.3/HfN1.1/HfN1.3/HfN1.1 4-layer CTL realized precise control of flat-band voltage (VFB) and VTH compared to the Hf-based MONOS with HfN1.1 1-layer CTL. The hysteresis width after the program operation was markedly decreased which was originated from the stable trap site formation at the interface of the multi CTL. The retention and fatigue characteristics were found to be remarkably improved for the Hf-based MONOS structure with HfN multi CTL.