Study Of Resistive Switching Characteristics And Mechanisms For Zirconium Oxide (Hafnium Oxide) Based Resistive Random Access Memory

In the 21st century,the information storage and processing are very important with the advent of age of Big data.In the semiconductor industry,memory accounts for a large share.At present,the memory is mainly floating gate flash memory based on silicon technology.However,the flash memory is facing the scaling limit in the process of continuous miniaturization,which limits the development of memory industry.In recent years,several emerging nonvolatile memory devices such as the phase change random access memory(PCRAM),ferroelectric random access memory(FeRAM),magnetic random access memory(MRAM)and resistive random access memory(RRAM)have attracted extensive attentions of a large number of researchers.Among these promising memory technologies,the RRAM have been widely studyed due to its simple structure,fast switching speed,high density,low operating consumption,and compatibility with standard CMOS process.Firstly,the performances of TiN/HfO2/ITO and TiN/HfO2/Pt have been studied under platinum(Pt)inert electrode and indium tin oxide(ITO)active electrode.The results have shown that the memory unit under the ITO electrode has self-limiting characteristics,which effectively reduces the operating power consumption of the device.Based on the previous results,the design of the TiN/HfO2/SiO2/ITO double layer device is improved and the operation power consumption farther decrease to 16 ?W.The paper focuses on the influence of the performance of TiN/ZrOx/Pt devices modulated by oxygen vacancy.By making TiN/ZrOx/Pt RRAM devices in different atmospheres(argon,N2/Ar mixture and O2/Ar mixture),it is found that the device with 8.06%nitrogen content has the best consistency of resistance parameters when it was fabricated in N2/Ar mixture atmospheres.According to the analysis of the conduction mechanism of the device,the sample made in N2/Ar atmospheres follows the ohmic mechanism in the low-resistance conduction mechanism,and the high-resistance conduction follows the Schottky conduction mechanism.Combined with the material analysis,it is concluded that oxygen ions(O2-)will gather around the tip of the filament due to the existence of doping nitrogen,so that the uniformity of the N-doped ZrOx device is improved by the reduction of O2-migration randomness in the operation process.Besides,the performance of TiN/HfO2/TiO2/Pt devices is improved by the application of the supercritical CO2 fluid(SCF)technology.The results show that the discreteness of the device's resistance change parameters is significantly improved after the procession and the resistance window of the device expands by 1.5 times.The performance improvement of the device is due to the fact that supercritical CO2 fluids carry water molecules to repair the dangling bonds in the film,improving the quality of the resistive layer film and reducing the device's low resistance value.Finally,a highly insulated HfO2 sidewall was built on the transparent ITO/Hf:SiO2/ITO structure resistive memory cell by inductively coupled plasma(ICP)etching technology.The results show that the resistive window of the device has been increased from 5 times to 16 times,and the dispersion of the resistive parameters has been improved.In summary,the performance of resistive switching is optimized by selecting the electrode,nitrogen doping of the switching layer,supercritical CO2 fluid treatment,and constructing the sidewall of Zirconium oxide(Hafnium oxide)based resistive memory and the relative mechanism is studied in this paper.This work lays the foundation for the resistive storage technology with large resistance window,long retention properties,and good uniformity of switching parameters and has important scientific significance and application value.