Ultra-low power Al2O3-based RRAM with 1μA reset current

Transition metal oxide (TMO) resistance random access memory (RRAM) is considered a promising candidate for future non-volatile memory application for fast switching speed, long retention time and superior scaling properties. In order to satisfy product requirements, elimination of the electroforming process of fresh RRAM device, sufficient program/erase voltage margin, and low power consumption are required. Among the various resistive layer materials, Al₂O₃ prepared by traditional sputtering method is so far not an attractive candidate due to its relatively small active voltage and large programming current compared to other TMO materials. In this paper, RRAM devices with atomic-layer deposited (ALD) Al₂O₃ as resistive layer material and Al electrodes are fabricated which show stable bipolar resistive switching behavior without the electro-forming process. In addition, the reset current is ultra-low (~1μA) with adequate switching voltage margin. To investigate the influence of Ti-interfacial layer on the Al₂O₃ switching mechanism, bi-layer top electrode Al/Ti/Al₂O₃/Pt memory cells were also fabricated for comparison. For these devices, a unipolar switching behavior was observed.