Oxide dual-layer memory element for scalable non-volatile cross-point memory technology

Abstract

We report a dual oxide layer as the active memory element of a scalable nonvolatile cross-point memory technology. The resistance change memory element is formed by a conductive metal oxide adjacent to an oxide tunnel barrier. Varying the as-deposited tunnel barrier thickness allows for control of the nominal current density and is targeted to meet the cell requirements for an ultra high density cross-point architecture. Excellent scaling of program and erase currents with electrode area and a continuous transition between program and erase state indicate that a uniform rather than a filamentary switching mechanism controls the device current both in the high and the low resistive state. A prior forming step is not required. The observed resistance change is caused by the exchange of oxygen ions between the conductive metal oxide and the tunnel oxide. Ion motion at room temperature is enabled by an exponential increase of the ion mobility under high electric fields during program and erase operations. The resistive switching effect of the device is explained by a change in the tunneling current due to an increase or decrease in effective tunnel barrier height. The barrier height varies due to changes in charge within the barrier as a result of oxygen ions moving in to or out of the tunnel barrier.