Access Strategies for Resistive Random Access Memory (RRAM)

In an RRAM array, it is important to avoid sneak current paths that result in inadvertent, non-negligible voltage and current inputs to unselected cells. At the same time, care must be taken not to allow excessive voltages or currents to selected cells, which could result in damage. For this reason, the choice of an appropriate cell access device is crucial. There is a natural tradeoff that a less leaky device is harder to turn ON. Thus, many devices that could provide sufficient ON-OFF ratio would require higher voltages for turning ON. However, too high a turn-ON voltage could result in breakdown of the RRAM due to transfer of the weight of the voltage from the access device to the RRAM. Consequently, the allowable voltage-current window must generally be restricted to fairly low currents and modest ON-OFF ratios. Assessing the compatibility of an RRAM with available access devices is a necessary step before determining the array architecture.