Effect of plasma treatment of resistive layer on a Cu/SiOx/Pt memory device

Abstract

In this paper, a 20-nm SiOx thin film was deposited on a Pt/Ti/SiO2/Si substrate using radio-frequency magnetron sputtering. A Cu top electrode was deposited to form a Cu/SiOx/Pt device. The device was reversibly switched between a low-resistance state and a high-resistance state using DC voltage sweeping. Because of its bipolar switching behavior and the device structure, the switching mechanism can be explained by the formation and rupture of Cu filaments within the SiOx layer. An Argon (Ar) plasma treatment was used to modify the SiOx layer, which stabilized the resistive switching and, thus, improved the switching dispersion. The Ar plasma treatment caused ion bombardment, which increased the Cu diffusion coefficient within the SiOx layer, thus decreasing the operating voltage. In addition, various level of bombardment within the SiOx film caused partial damage of the SiOx film, which influenced the switching dispersion. The Ar-treated device in the 20-s plasma treatment demonstrated favorable memory properties, including a long retention time, nondestructive readout, and high resistance ratio, indicating that it could be viably applied in next-generation nonvolatile memory devices.