Study On The Resistive Switching Properties And Preparation Of Tantalum Oxide Based Resistive Switching Device

With the semiconductor technology innovatived,the field of memory is rapidly development.Flash memory has showed more and more limits,so it is important to study the new memory which can meet society's needs.Now several new memorys has came into society,including Ferroelectric random access memory(FeRAM),Magnetic random access memory(MRAM),Phase change random access memory(PRAM)and Resistive random access memory(RRAM).The Resistive random access memory successly attracted more attentions because of its fast read and write speed,low power consumption and conventional CMOS(Complementary Metal Oxide Semiconductor)process compatibility.The tantalum oxide-based resistance switching memory became more and more important because of its superior endurance performance.In this paper,we designed the tantalum oxide-based resistance switching memory by adding a titanium layer in the device to improve its performance.We optimized the oxygen partial pressure and thickness conditions of tantalum oxide film,the location of titanium layer in the device and change the test conditions to improve the device performance.We found the best performance structure is Ta/Ti(1nm)/Ta Ox/Pt,where oxygen partial pressure of TaO_x is 5%,thickness of TaO_x is 10 nm.The test conditions of the structure is Vset=2v,Vreset=-2v,Icc=5mA.Compared to the without titanium layer structure(Ta/TaO_x/Pt),the performance of endurance and uniformity are greatly improved.In order to analysis the role of titanium layer,We designed three kinds of samples,including Ta/TaO_x/Pt,Ta/Ti(1nm)/TaO_x/Pt and Ta/Ti(2nm)/TaO_x/Pt.We found that the sample added the titanium layer have stable self-rectifying phenomenon,and with the titanium layer thickness increasingly,the device shows a lower self-rectifying current,that the titanium layer capture oxygen ions during the Set proess,and then transform to titanium oxide layer as series resistance in device.And acts as source of oxygen ions in Reset proess,provides sufficient oxygen ions into the tantalum oxide film.Because titanium's ability to seize the oxygen ions is stronger than tantalum,therefore this structure is more stable.We also established relevant models to explain the proess of Set and Reset in this sample.Finally,we prepared laminate structure sample.We tested the sample without titanium layer,found the performance is not good,so we added the titanium layer into this sample and designed the Ta/Ti/TaO2-x/Ta2O5-x/Pt samples.Compared to the without titanium layer sample(Ta/TaO2-x/Ta2O5-x/Pt),titanium layer improved the device performance.The model is suitable for the laminate structure sample too,verified the practicability of the model.Through analysis of tantalum oxide-based resistive memories,our work will provide a theoretical sense on RRAM performance optimization and industrial applications.