Effect of ReRAM-stack asymmetry on read disturb immunity

We investigated the effect of ReRAM-stack asymmetry on read disturb immunity. Stacking stoichiometric Ta₂O₅ and ultrathin TiO₂ led to bipolar switching property. Filament (conduction path) penetrated both Ta₂O₅ and TiO₂ layer. Because single Ta₂O₅ film has no switching property, the resistance was not changed under positive bias on Ta₂O₅-side electrode. Under negative bias, the resistance of the filament near TiO₂-side electrode increases because of anodic oxidation. A high read-disturb immunity were achieved by using the 1T1R ReRAM of this stack. These results can be attributed to the asymmetric switching behavior of the stoichiometric Ta₂O₅/ultrathin-TiO₂ stack.