Preparation And Performance Study Of Copper Oxide And Zinc Oxide Basic Rram

The bottleneck of modern information technology is storage capacity and storage speed of memory device, because the size of Si-base device has achieved its physical theoretical limit. Due to its high density, low cost, fast write and read access, low energy operation and high performance, RRAM has attracted most attention.In this paper, Al/CuxO/Cu structure, Al/Zn O/Cu strcture and Al/Cu O/Cu structure RRAM were prepared. Using analysis method such as XRD, XPS, SEM and AFM, we found the influence of magnetron sputtering parameters to composition, structure and surface roughness of films. Prepare series of RRAMs under different magnetron sputtering parameters, analize the theory of resitive switching and influence of composition, size of grain, surface roughness. In this paper, the main content includes:(1) Due to that Cu film was used as bottom electrode in every RRAM, and crystal orientation and surface roughness of BE influence growth of resistive switching layer, so first we should optimizate the growth parameters of Cu bottom electrode film. Composite of Cu crystallization direction, sputtering rate, surface roughness and other factors, we determine the growth parameters is that sputtering power is 100 W, sputtering pressure is 1Pa, argon flow rate is 40 sccm, sputtering time is 20 min.(2) Al/CuxO/Cu RRAM was prepared by RF magnetron sputtering, bipolar resistance switching behavior was found, and the ratio of RHRS/RLRS is higher than 1000 times. These performances meet the requirements of practical application of RRAM. We determined that the phenomenon of HRS could be explained with SCLC theory, and LRS could be explained with conductive filament. The lifetime is over 1000 cycles. As the composition of switching film transform from Cu O to Cu2 O, the forming voltage continuously decrease, the SET voltage almost unchanged, I can approximately think that the forming process is free when the composition is whole of Cu2 O. Larger the grain size, higher the resistance of HRS and LRS. This maybe associated with that the conductive filament may form in the grain boundary.(3) Al/Zn O/Cu RRAM was prepared by RF magnetron sputtering, and the ratio fo RHRS/RLRS is about 100. Its storage mechanism is consistent with the Al/CuxO/Cu RRAM, but the stability is higher. The larger the grain size is, the higher the SET voltage and resistance of HRS and LRS is. There is little influence of surface roughness.(4) Compared the mechanism of Al/Cu O/Zn O/Cu RRAM(bilayer device) and Al/Cu/Zn O RRAM(single layer device), we found that the mechanism of resistance switching of BLdevice is familiar with SL device. BL device exhibits more excellent switching performance, higher ratio of RHRS/RLRS(over 300), higher threshold voltage, more concentrate RHRS and RLRS, which means more excellent endurance. SL device exhibit more concentrate and smaller SET voltage which is also important for practical application. Cu O layer plays important roles in BL device.