Improved Environment Stability of Y₂O₃ RRAM Devices with Au Passivated Ag Top Electrodes

In this study, we fabricated sol-gel-processed Y₂O₃-based resistive random-access memory (RRAM) devices. The fabricated Y₂O₃ RRAM devices exhibited conventional bipolar RRAM device characteristics and did not require the forming process. The long-term stability of the RRAM devices was investigated. The Y₂O₃ RRAM devices with a 20 nm thick Ag top electrode showed an increase in the low resistance state (LRS) and high resistance state (HRS) and a decrease in the HRS/LRS ratio after 30 days owing to oxidation and corrosion of the Ag electrodes. However, Y₂O₃ RRAM devices with inert Au-passivated Ag electrodes showed a constant RRAM device performance after 30 days. The 150 nm-thick Au passivation layer successfully suppressed the oxidation and corrosion of the Ag electrode by minimizing the chance of contact between water or oxygen molecules and Ag electrodes. The Au/Ag/Y₂O₃/ITO RRAM devices exhibited more than 300 switching cycles with a decent resistive window (>10³). They maintained constant LRS and HRS resistances for up to 10⁴ s, without significant degradation of nonvolatile memory properties for 30 days while stored in air.