In this work, we present a thorough statistical characterization of cycling variability and Random Telegraph Noise (RTN) in HfO2-based Resistive Random Access Memory (RRAM) cells in Low Resistive State (LRS). Devices are tested under a variety of operational conditions. A Factorial Hidden Markov Model (FHMM) analysis is exploited to extrapolate the properties of the traps causing multi-level RTN in LRS. The trapping and de-trapping of charge carriers into/out of defects located in the proximity of the conductive filament results in a shielding effect on a portion of the conductive filament, leading to the observed RTN current fluctuations. The variations of the current observed at subsequent set/reset cycles are instead attributed to the stochastic variations in the filament due to oxidation/reduction processes during reset and set operations, respectively. The statistical characterization of RTN and cycling variability does not show correlation between these phenomena.
Analysis of RTN and cycling variability in HfO2 RRAM devices in LRS / Puglisi, Francesco Maria; Pavan, Paolo; Larcher, Luca; Padovani, Andrea. - ELETTRONICO. - (2014), pp. 246-249. (Intervento presentato al convegno 44th European Solid-State Device Research Conference, ESSDERC 2014 tenutosi a Venice (I) nel 22–26 September 2014) [10.1109/ESSDERC.2014.6948806].