Research On Physical Mechanism And Stateful Logic Realization Of HfO_x Memristors

As a new type of non-volatile memory device,memristor has attracted much attention because of its excellent performance such as high speed,low power consumption,easy integration and compatibility with CMOS process.In order to continuously optimize the performance of memristors,the characterization of their physical mechanisms has always been one of the important research directions of memristors.With the proposal of non-volatile logic operation scheme based on memristor,the integration of storage and computation has been successfully realized.Memristive logic provides a new technology development direction for breaking through von Neumann bottleneck and bypassing the miniaturization limit.Memristor is also expected to become the core device of future computing architecture.In this paper,based on the physical mechanism and logical implementation of memristors,firstly,random telegraph noise?RTN?in memristors was taken as the starting point of physical mechanism research.Pt/Ti/HfO₂/W memristor was selected as the research object.The basic electrical characteristics of the device were tested and the conduction mechanism of the device under different resistance states was analyzed by mechanism fitting.By adjusting reset cut-off voltage,several stable intermediate resistance states of Pt/Ti/HfO₂/W memristors were obtained.Taking the difference of RTN characteristics under different resistance states as the research direction,it was found that the complexity of RTN increased with the resistance states,which mean that the number of oxygen vacancy traps increased with the resistance states.The relationship between the characteristics of RTN and the reading voltage was further tested.It was found that Joule heat affected the process of electron trapping/de-trapping.Combining the conductive mechanism of the device with the results of RTN measurements,a conductive filament model based on oxygen vacancy trap was established to explain the evolution of oxygen vacancy traps in devices with resistive states.Next,taking Pt/HfO₂/TiN memristor as the research object,combining with the measurement results of electrical characteristics,the NOR logic circuit based on Pt/HfO₂/TiN memristor was designed,and the NOR logic function was realized experimentally in the packaged Pt/HfO₂/TiN memristor.Based on the circuit structure of NOR logic,several basic Boolean logic gates,such as OR,NOT,TRANSFER,NAND,IMP and AND,were proposed successively,and their feasibility is verified by experiments in practical devices.Two kinds of one-bit full adder and subtraction circuits and a two-bit multiplier circuit were designed for different computing requirements.The feasibilities of the circuit were verified by simulation in Hspice software.The research work in this paper is helpful to understand the migration and evolution process of oxygen vacancies and traps with the resistance states of memristor,and also provides a good reference for the design of arithmetic operation circuit based on memristive logic.