Study On Construction And On-off Switching Properties Of ZnO-based RRAM

In recent years, with the rapidly development of storage and the shortage of traditionalnon-volatile memories of flash, being a next generation non-volatile memories, resistancerandom access memory has attracted widely attention for its better performance on storagecapacity, such as small size, simple structure, faster operation speed, higher integration, lowerconsumption, better compatibility with CMOS process. ZnO has been studied in RRAM of itswell electrical properties.In this paper, construction and on-off switching properties of ZnO-based RRAM wasstudied. The basic structure of RRAM was Metal-Insulator-Metal. We used ultra-high vacuummagnetron sputtering to prepare functional layer of ZnO and the electrodes. Micro-structureand resistive switching (RS) properties of ZnO-based RRAM were characterized by AFM,XRD, SPA and so on, respectively.Specific research contents and results are as follows:1) Effects of oxygen partial pressure, substrate temperature and thickness on ZnO werestudied. The results illustrated that the best morphology and RS characters was obtained underthe oxygen partial pressure of 60% at 200℃.Thickness of ZnO film was only influenced thevoltage of forming process.2) Effects of electrodes on ZnO-based RRAM were studied. After electrical testing ofZnO-based RRAM cells, the results showed that with a relative low Schottky barrier withZnO, the unipolar switching characters were observed under Cu, Au and Pt. As for the higherSchottky barrier of Ag electrode, bipolar was observed. While nothing RS properties wasobserver of Al electrode, the reason would be the Al electrode was oxidized during thesputtering of ZnO. We analyzed that decreasing the scall of TE properly can decrease thecurrent of reset and increasing the value of forming resistance more than 106, which canincrease the stability of RRAM.3) An innovative structure of 1C1R RRAM of ZnO/Metal/SiO2/Metal/Substrate wasdesigned and fabricated. It illustrated that the set and reset voltages were decreased bycharge-discharge properties of capacitance under plus-minus pulse voltage, and the d-valuereached to 0.6V. The P/N structure of RRAM was analyzed at the point of decreasing Resetcurrent.Above all, the preparation process, electrodes, the innovative structure 1C1R ofZnO-based RRAM were studied in this paper. RS properties and the aspects of decreasing the power consumption of ZnO-based RRAM were systematically studied, which contributes tothe further studies of RRAM and its application.