Diode-less nano-scale ZrOx/HfOx RRAM device with excellent switching uniformity and reliability for high-density cross-point memory applications

We report excellent switching uniformity and reliability of RRAM device with ZrO_x/HfO_x bi-layer films. Precise control of the oxygen vacancy concentration in HfO₂ layer was achieved by depositing thin Zr metal (2-15nm) layer. Scaling down active device area (φ=50 nm) and film thickness (<;2-5 nm) can significantly minimize the extrinsic defects-related non-uniform switching which was normally observed in large area (φ >;um) device, with higher active layer thickness (>;10 nm). Using back-to-back connection of two RRAM devices, we confirmed feasibility of a diode-free cross-point array with a wide readout margin and stable data reading. Considering excellent electrical and reliability characteristics of diode-free RRAM device, shows a great promise for future high density cross-point memory devices.