The resistive switching characteristics in tantalum oxide-based RRAM device via combining high-temperature sputtering with plasma oxidation

摘要

High-temperature (320°C) sputtering combined with plasma oxidation was employed to form TaO/TaO bi-layer devices. For comparison, Pt/TaO/Pt structures, where TaO layers were reactively sputtered at room temperature and 320°C, respectively, were fabricated. No resistive switching was observed for the devices where TaO was deposited at room temperature, while a few switching cycles were observed for the devices where TaO was deposited at 320°C. By combining high-temperature sputtering with plasma oxidation, the TaO/TaO bi-layer devices exhibited much more and better I-V cycles. The reset current was reduced drastically (20mA→100μA), and the uniformity of device performance was enhanced. Resistance switching of the TaO/TaO bi-layer devices under voltage pulses was achieved, and Roff/Ron ratio was ~10. The formation of a large quantity of TaO was confirmed by X-ray photoelectron spectroscopy after the plasma oxidation. A comparison and analysis of improvement in device performance was conducted. It is demonstrated that combining high-temperature sputtering with plasma oxidation is able to improve resistive switching characteristics, and is an effective and feasible method for reducing reset current and enhancing device stability. The improvement was attributed to formation of TaO on the surface of the TaO layer by plasma oxidation.