HfOx based vertical resistive random access memory for cost-effective 3D cross-point architecture without cell selector

Double-layer stacked HfOx vertical RRAM is demonstrated for 3D cross-point architecture using a cost-effective fabrication process. Electrode/oxide interface engineering using TiON layer results in non-linear I-V suitable for the selector-less array. The fabricated HfOx vertical RRAM shows excellent performances such as reset current (<;50μA), switching speed (~50ns), switching endurance (>10⁸ cycles), half-selected read disturbance immunity (>10⁹ cycles), retention (>10⁵s @125^oC). Moreover, a unique write/read scheme is proposed for 3D cross-point architecture. Analysis shows that for such 3D selector-less array, a large R_on (~100kΩ) from the non-linear I-V helps reduce the sneak path current, and a low interconnect resistance using metal planes as word lines reduces the undesirable voltage drop on the interconnect. As a conservative estimate, simulation shows that Mb-scale array without cell selector is achievable.