Investigation On HfO_x-based Resistive Switching Memory And Its Crosstalk In Integration

Resistive Switching Memories（RRAMs）is the most attractive candidate for next generation non-volatile memory（NVM）owing to its many advantages,such as a simple capacitor-like structure,compact 4F² cell size etc.A variety of materials can be used in dielectric layer,such as transition metal oxides（HfO_x,Ta O_x,and Ti O_x etc）.HfO_x-based RRAMs owing to its many advantages,such as faster switching and low operation voltage,have widely appreciated attention.However,the problems such as parameters consistency poorly,switching mechanism indistinctly and integrated crosstalk,still exist.Based on the above problems,this paper carried out the following investigation:Aiming at the problem of parameter consistency poorly,HfO₂ was used to establish ITO/HfO_x/Ti N（IHT）and ITO/HfO_x/Ti O_y/Ti N（IHTT）stacked structure.Through testing the different thickness and cell size of IHT devices,the endurance in all devices can reachs 10⁴cycles,and the consistency of HRS/LRS was also improved.Through testing the IHTT with different thickness Ti O_y interlayer,the results indicated that the endurance in device with2-3nm thickness interlayer can reachs 10⁴ cycles or more and the operating voltage consistency was improved obviously.The transformation mechanism of IHT devices through fitting analysis of IV-curves in the double logarithmic coordinate indicates that high resistance state（HRS）is SCLC and low resistance state（LRS）is ohmic mechanism.Statistical analysis of the Set and Reset processes shows that this device exhibits quantized conductance behavior.For the issue of integrated crosstalk,two kinds of selector with different materials were successfully constructed,including Ag/HfO_x based and Ag/HfO_xN_y based devices.The results of measure show that the ratio of on/off can reach 10⁶ times and 10⁷ times,respectively.Compared with Ag/HfO_x-based devices,Ag/HfO_xN_y-based devices have better operating voltage consistency and higher driving current.By connecting the Ag/HfO_xN_y and Ru/HfO_x,the measure indicated that the leakage current is only 1p A.HSPICE simulation is performed for crossbar based on Ag/HfO_xN_y-Ru/HfO_x integrated cell.The dependence of the read margin on the drive current,crosstalk current,and sensing resistor,was investigated and the integrated crosstalk solution of 1S1R is verified by simulation.