Reliability Consideration Of Resistive Randomaccess Memory Based On ZnO Films

The present era, with the rapid development of information industry, the memory has beenwidely used in various electronic products, has brought great convenience to our daily work andlife. Furthermore, people will move higher memory performance needs, such as access speed, lowpower, small size, long life, non-volatile and so on. The new non-volatile random access memorynow, phase change memory(PRAM), Ferroelectric RAM(FRAM), magnetoresistive memory(MRAM), resistance change memory(RRAM) and other non-electric charge stored in the form ofdata has been a great concern. Among them,resistance-change memory has many uniqueadvantages, such as simple structure, high storage density, fast read and write, the data can bemaintained for a long time, the three-dimensional integration; addition, resistance change memoryfabrication and silicon CMOS compatible process, which for practical application provides a strongguarantee. ZnO is an important Ⅱ-Ⅵ compound semiconductor materials, thermoelectric, gas,piezoelectric, optical and other fields have a wide range of applications. In recent years, studies ofZnO-based thin-film resistive switching characteristics are also increasing. However, ZnO-basedthin-film resistive switching reliability is still very weak, in order to make the device as early aspossible to achieve practical standards,it is necessary to study its reliability, and making furtherelucidate the mechanism of performance.In this paper, vacuum coating equipment production TE/ZnO/BE(TE, top electrode, is theelectrode; BE, bottom electrode, as the lower electrode) sandwich structure of the resistanceswitching devices, which use a DC magnetron sputtering of ZnO films by electron beamevaporation deposition electrode.And using UV-visible spectroscopy, film thickness tester, X-raydiffraction, scanning electron microscopy, IV characteristics tester for ZnO films and resistanceswitching devices were analyzed to study the film thickness, the lower electrode material, Ti dopingon the device impact of switching characteristics,the main conclusion was as follows:(1)Cu/ZnO/n+-Si structure of the device for preparing the resistive switching characteristics ofthe device is affected by the thickness of the ZnO film obviously, very thin and relatively thick ZnOthin film resistor switching devices, will not appear forming phenomenon; within a certainthickness range, are forming, set, reset process; When ZnO when the film thickness is reduced tothe proper thickness, ZnO-based thin-film resistive switching devices can be achieved withoutforming on exhibit resistance switching characteristics, without forming device, set the voltage issmall, reset voltage fluctuation is small, good stability and reliability.(2)Respectively, the Pt metal, ITO film and heavily doped single-crystal silicon as the lower electrode, prepared Cu/ZnO/BEs memory structure. Produced under different electrode resistanceswitching devices are unipolar memory. In the high-impedance state, the conduction mechanism ofZnO thin films for space-charge-limited current; in the low resistance state, the conductive film isohmic conduction mechanism.Materials of these three lower electrode are more stable, and lessprone to react with ZnO films are suitable for the ZnO-based thin film as the electrode material ofthe resistive switch, improved device reliability.(3)Studied the Pt/ZnO:Ti/n+-Si resistive switching characteristics of the device.Pt/ZnO:Ti(3%)/n+-Si structure is optimal resistive switching characteristics, namely, low operatingvoltage, reset voltage decreases, high stability and reliability significantly. In addition, thehigh-impedance state(HRS) and low resistance state(LRS) between OFF/ON ratio is greater thanthe average of102, which is enough to meet the requirements of commercial applications.