Ta2O5-y-based ReRAM device with annealing-free Ag:ZrNx-based bilayer selector device

Abstract

Sneak path current suppression is indispensable for realizing resistive random-access memory-based high-density crossbar array (CBA) architectures. Therefore, we present a Pt/Ta2O5-y/Ta/Pt nonvolatile resistive switching (RS) device and a selector device with a Pt/Ag-doped ZrNx/Pt configuration, representing bidirectional threshold switching (TS). The cross-sections of both devices were investigated via transmission electron microscopy, and the variation in the Ag content was examined via energydispersive X-ray spectroscopy. The radio frequency-sputtered RS device exhibited good switching voltage uniformity (Delta V-SET and Delta V-RESET approximate to +/- 0.15) and a large memory window (similar to 5 x 10(2)). The selector device was developed via co-sputtering of Ag and ZrN, and the optimized device exhibited excellent selectivity (>10(6)), a very low OFF-current (similar to 10(-11) A), a very short delay time (similar to 70 ns), and stable TS characteristics. On the basis of the optimized structure, a one-selector one-memory device was fabricated by stacking these two devices, and its performance was investigated. Equivalent circuit analysis of the proposed one-selector one-resistor (1S1R) devices in a CBA configuration was performed, and the optimal array size was estimated to demonstrate the applicability of the proposed structure. The results indicated that the maximum permissible crossbar array size of the 1S1R device with the Pt/Ag-doped ZrNx/Pt/Ta2O5-y/Ta/Pt structure was 2.56 x 10(14) (N-2, N = 1.6 x 10(7)). (C) 2020 Elsevier B.V. All rights reserved.