(Invited) Resistive Random Access Memory for Storage Class Applications
We show that the sneak path challenge has been overcome by utilizing a Field Assisted Superlinear Threshold (FAST) selector . The FAST selector device uses an insulating amorphous material which provides volatile switching at critical electric field. Excellent selector performance is presented, including high selectivity of > 107, sharp switching slope of < 5mV/dec., and large endurance of > 1011. The low fabrication temperature (≤300°C) of the FAST selector allows 3D stacking of 1S1R memory layers. It is also demonstrated that a volatile switch based selector has inherent benefits such as low voltage overhead for 1S1R integration and high read voltage margin.
For the 1S1R demonstration, electrochemical metallization RRAM with a sub-5nm filament is utilized. The RRAM device offers a self-current-limiting feature during the program operation . The self-limited program obviates the need for external current compliance, which can increase the number of concurrent programs in the 1S1R cross-point architecture with reduced power consumption and increased reliability benefits. Furthermore, the hold voltage property (snap-back behavior) of a FAST selector allows novel sensing techniques such as Resistance Ratio Amplification (RRA) which amplifies the intrinsic ON/OFF ratio of RRAM by a factor of > 104 . Besides the direct advantage of increased memory ON/OFF ratio, the RRA technique also reduces BER and increases read bandwidth of the RRAM array. The integrated self-current-limited RRAM with FAST selector enables the high density and high performance 1S1R RRAM technology.
 S. H. Jo, T. Kumar, S. Narayanan, W. D. Lu and H. Nazarian, “3D-stackable crossbar resistive memory based on field assisted superlinear threshold (FAST) selector,” IEDM, 2014.