Investigation on the RESET switching mechanism of bipolar Cu/HfO2/Pt RRAM devices with a statistical methodology

The RESET switching of bipolar Cu/HfO2/Pt resistance random access memory (RRAM) is investigated. With a statistical methodology, we systematically analyze the RESET voltage (V-RESET) and RESET current (I-RESET). V-RESET shows a U-shape distribution as a function of R-ON according to the scatter plot of the raw experimental data. After data correction by a series resistance (R-S), V-RESET is nearly constant, while I-RESET decreases linearly with R-CF. These behaviours are consistent with the thermal dissolution model of RESET. Moreover, the I-RESET and V-RESET distributions are strongly affected by the R-ON distribution. Using a 'resistance screening' method, the I-RESET and V-RESET distributions are found to be compatible with the Weibull distribution model. The Weibull slopes of the V-RESET and I-RESET distributions are independent of R-CF, indicating that the RESET point corresponds to the initial phase of conductive filament (CF) dissolution, according to our cell-based model for the unipolar RESET of RRAM devices. The scale factor of the V-RESET distributions is roughly constant, while that of the I-RESET distributions scale with 1/R-CF. Accordingly, the RESET switching of the HfO2-based solid electrolyte memory is compatible with the thermal dissolution mechanism, improving our understanding on the physics of resistive switching of RRAM devices.