Research On Resistive Random Memory Based On Aluminum Nitride

With the advent of the era of big data,the emerging fields such as cloud computing,AI and the Io T have sharply increased the industry's demand for storage chips.However,with the process shrinking,the traditional non-volatile memory is about to reach the physical limit.It is difficult to furtherly improve its performance and reliability.Faced with such a dilemma,the industry is extremely urgent for the development of a new-type non-volatile memory.As a kind of new-type non-volatile memory,resistive random access memory(RRAM)has the advantages of good scalability,simple structure,fast reading and writing speed,low power consumption,high reliability and compatibility with CMOS technology.It has great potential as the next generation of mainstream non-volatile memory.Aluminum nitride has a wide band gap,high thermal conductivity,high melting point and good chemical reaction stability,which is an excellent material for RRAM device.This article chooses aluminum nitride-based resistive random access memory as the research object,and studies the influence of crystallinity on the performance of resistive random access memory.The research content of this article is as follows:1.Firstly,based on the principle of molecular dynamics,a large system structure was used to simulate the structural changes of Al N under rapid thermal annealing at different temperatures.The crystallization process which could not be observed experimentally was verified.It proves that the rapid thermal annealing process can effectively improve the crystallinity of the system.In this process,the defect concentration of the system is found reduced.Second,the influence of defect concentration on the system structure and band structure is analyzed through first-principles simulation.GGA+U method is used to make the simulation results closer to the experiment results.The simulation shows that the electrons in the system are more easily excited by the external energy and the film conducts electricity more easily as the defect concentration increases.On this basis,the I-V characteristics of films with different lengths are simulated.The results show that as the grain size increases,the current gradually decreases.2.In order to verify the simulation results,Al N films were processed by rapid thermal annealing process,and resistive random memory devices with Ta/Al N/Pt structure were fabricated.By comparing the I-V characteristics of devices processed at different annealing temperatures,it is found that the increased crystallinity of the Al N film increases the switching voltage and storage window,and improves the reliability of the device.It is found that the conductive transport mechanism conforms to both the space charge limited conduction(SCLC)model and the schottky emission model through fitting.Based on the above experimental results and conduction mechanism,the reasons for the change in device performance caused by different crystallinities were analyzed.We believe that the increase in crystallinity results in a decrease in the concentration of nitrogen vacancies in the Al N film and an enhancement of the grain boundary effect,which in turn leads to increasing storage window only at the cost of a slight increase in the switching voltage.