Statistical Study of RRAM MLC SET Variability Induced by Filament Morphology

Abstract

This paper establishes the correlation between RRAM multilevel-cell (MLC) stochastic SET variability and random telegraph noise (RTN). We show that a smaller diameter (d(D)) of locally connecting/rupturing conductive filament (CF) and larger distance of gap (d(G)) between CF and electrode demonstrate both steeper Weibull slope beta with a relaxed SET-disturb margin by 0.4 V and 36x improvement in RTN robustness. This is achieved by lower current compliances (I-COMP) of 100 mu A and larger RESET stopping voltage (V-RESET) of -4.5 V for smaller dD and larger dG with leaving less residual oxygen vacancies (V-o(+2)) in the gap region. Results from the Kinetic Monte Carlo (KMC) modeling also support these findings.