Fabrication And Characterization Of Resistive Switching Based On TiO₂ Films

Today, memory have been applied to a variety of electronic product, and play a more and more important role. With the rapid development of electronic technique and integrated circuits, people make a claim for better performance. Though flash have many advantages, flash feature sizes can't continue to shrink, or the thickness of gate oxide will reduce according to the scaling rule. As a result, the tunneling effect appears to be obviously, leading to the increase of the leakage current, which deteriorates the reliability of flash devices. Therefore, It limits its further development. In view of above-mentioned question, people began to study new non-volatile memory. At present, a variety of new non-volatile memory have developed, such as Ferroelectric Random Access Memory (FeRAM), Phase Change Random Access Memory (PCRAM), Magnetron resistive Random Access Memory (MRAM) and Resistive Random Access Memory (ReRAM). And among these, ReRAM has attracted great attention due to simple preparation method, high-density mass storge, rapid operation, nonmultilative read, low power consumption, low cost, good compatibility with conventional CMOS process. Therefore, It is studied widely and expected to be the next generation of universal memory application.TiO2 thin film is a semiconductor materials, and exhibit many attractive characteristics, they have been more and more investigated. TiO2 thin film material recently attracts great interest for the application in photocatalyst, sensing, photoelectrolysis, solar sell and nonvolatile memory elements in semiconductor memory devices. Therefore, it is necessary to study resistive switching property of TiO2 thin films.In this paper, TiO2 thin films have been fabricated by using magnetron sputtering method. The influences of the different process on the properties of the thin films have been studied, such as crystalline structure, resistive switching characteristics and high/low resistance. On the basis of the experimental results, mechanism of resistive switching has also been discussed. In addition, we also prepared TiO2 on soft substrate, and studied their relative property.The results show that:TiO2 thin films fabricated by magnetron sputtering method exhibit reversible and steady unipolar resistive switching behaviors, and it's found that the forming voltage is linearly increased with thickness of thin films. The energy required for the rupture of filament in the process of reset is related to the amount of oxygen defects. C-V analysis show that TiO2 thin films exhibit capacitance characteristics at high resistance state. O2 content and annealing temperature have a great effect on high resistance. Besides, it's found that the conduction mechanisms dominating the low and high resistive states are Ohmic behavior and Space Charge Limit Current, respectively. Soft ReRAM have good resistive switching characteristics.