Multi-level 2-bit/cell operation utilizing Hf-based metal/oxide/nitride/oxide/silicon nonvolatile memory with HfO₂ and HfON tunneling layer

Abstract

This paper investigated the multi-level 2-bit/cell operation utilizing a Hf-based metal/oxide/nitride/oxide/silicon (MONOS) nonvolatile memory (NVM) device with a HfO2 and HfON tunneling layer (TL). The 2-bit/cell operation is realized by utilizing the localized charge injection method. It was found that drain-current–gate-voltage (I D–V G) characteristics of the programmed states were affected by asymmetry localized in a trapped location along the channel direction. Moreover, the amount of localized trapped charge is strongly affected by drain-source voltage (V DS) in the case of HfON TL. HfON TL shows distinguishable separated all programmed states compared to HfO2 TL. Finally, it was found that all programmed states of HfO2 and HfON TL show similar characteristics according to the channel length and width (L/W) of 2–10/15–90 μm.