Research On The Reliability Of Resistive Random Access Memory Based On A Stack Structure

With the improvement of IC integration,the feature size of devices are shrinking,and the traditional non-volatile memory is facing the bottleneck of development.On the one hand,the shrinking device size means the thickness of floating gate need to be decreased at the same time,on the other hand,a too thin gate will lead to a high leakage current,electrical breakdown and other problems.RRAM devices have a series of advantages,such as simple structure,good scalability,fast reading and writing speed,high reliability,compatibility with CMOS process,etc.They are very competitive next generation non-volatile memory devices,which have attracted wide attention of researchers.In this paper,the reliability of resistive devices is studied.The main contents are as follows:1.In this paper,in order to investigate the effect of different silicon nitrogen ratios of SiN_x dielectric layers on device characteristics,SiN_x resistive switching dielectric layers were prepared by plasma enhanced chemical vapor deposition?PECVD?.By adjusting the ratio of SiH₄ to NH₃ during the preparation of SiN_x,three groups of SiN_x dielectric layers with different Si/N ratios?different x values?were fabricated.Ta and PT were prepared by DC sputtering as top and bottom electrodes,respectively.The test results show that devices with different Si/N ratios have significant differences in the high resistance state current.After in-depth analysis,a Schottky barrier modulation effect was proposed to explain this phenomenon.2.The core objective of this paper is to improve the reliability of RRAM devices.The SiN_x dielectric layers were prepared by RF sputtering.Because it can provide a large amount of defects?Si dangling?,Si₃N₄ was chosen as a target.So that the initial state of the device may be low resistance state,and the forming process is omitted.It has great significance for improving the reliability of devices.During the research,it is found that increasing the sputtering temperature can improve the quality of the films,increase the compactness,and reduce the defects and holes.3.In this paper,in order to further improve the reliability of devices,a SiN_x/SiN_x:Pt/SiN_x stacked structure was prepared by embedding Pt nanoparticles in situ using RF co-sputtering.It can not only make devices have a stable initial low resistance state,but also effectively reduce the random fluctuation of the operating parameters,improve the retention and endurance characteristics.By this method,it realizes the preparation of forming-free RRAM devices with high reliability.