Modeling the Impact of Reset Depth on Vacancy-Induced Filament Perturbations in HfO2 RRAM.

Random telegraph noise in resistive switching memory devices is governed by two distinct mechanisms—oxygen vacancy perturbations in the filament as well as the electron trapping–detrapping phenomenon. In this letter, we focus on the dominant role of vacancies in governing the stability of the filament in the high resistance state and characterize the dependence of the read disturb voltage (VDIST) on the depth of the reset level during switching. Our slow voltage ramp read disturb tests at different reset levels indicate the possibility of filamentary instability even for read voltages lower than the standard value of 0.10 V. These experimental trends can be well explained using the quantum point contact model for conduction in the filament, as deeper reset levels induce very steep potential gradients at the two ends of the constriction that make the filaments highly unstable and susceptible to structural modifications due to vacancy generation and/or transport during memory read operation. [ABSTRACT FROM PUBLISHER]