Research On Silicon Nitride Based Stacked Resistive Memory

With the rapid development of 5G,big data,artificial intelligence,the Internet of Things and other high-tech industries,the integration and performance of memory are increasing day by day.However,the traditional semiconductor memory is gradually approaching its physical limitations after decades of development.The high technology industry needs new type memories with more excellent performance and higher speed.At present,many new memories have been invented by researchers.Among these memories,resistive random access memory(RRAM)has attracted great attention for its simple structure,low cost,high integration degree as well as its compatibility with conventional Sicomplementary metal-oxide-semiconductor processing.Within a variety of resistive materials,SiN_xis more attractive because of its excellent performance,low power consumption and other advantage.In this paper,a SiN_x/AlO_xlaminated device was constructed to improve RS performance,and the microscopic mechanism of resistance was deeply studied.The specific research and results are as follows:1.The essay concentrates on analyzing the Ta/SiN_x/AlO_x/Pt laminated RRAM with different film thickness.And the effects of resistance layer and insulation layer thickness on the electrical characteristics and resistance mechanism of devices are explored.Firstly,the comparison between the single RRAM and the SiN_x/AlO_xlaminated RRAM with different AlO_xfilm thickness is made.It is observed that the AlO_xinsulation layer reduces the working voltage,decrease the power consumption and significantly improve the stability of the device.Then,the conductive mechanism and resistance model of the device are analyzed.It is found that the AlO_xinsulating layer changes the conductive mechanism of RRAM,thus improving the performance of the device.At the same time,it is also found that the 3nm AlO_xinsulating layer will greatly increase the Forming voltage of the device,thus reducing the device window and making it easy to misread.Finally,the influence of SiN_xresistive layer with different thickness on the laminated devices is also studied.It is found that 5nm SiN_xresistive layer makes the laminated devices dominated by the Schottky emission mechanism,which reduces the device window and increases the power consumption,while the RRAM composed of 10nm or more thick SiN_xlayer has good performance.2.In order to further improve the device performance and explore the micro-mechanism of the device,the influence of N/Siratio on the properties of SiN_x/AlO_xRRAM devices was studied.It is found that the RRAM exhibited nonlinear properties when the device has a large N/Siratio.In this paper,the crosstalk problem of high integrated memory array and the existing solution are introduced firstly,as well as the definition of nonlinearity and the advantages of solving the crosstalk problem are expounded.Then,the resistive layer of SiN_xwas prepared by PECVD(Plasma Enhancement Chemical Vapor Deposition),and we changed the ratio of NH₃to SiH₄in the process to obtain the resistive layer devices with different N/Siratio.After further study,it is found that the nonlinearity of LRS is due to the tunneling of electrons through the AlO_xinsulator,and the tunneling mechanism varies with the applied voltage.At the same time,it is also found that when the NH₃flow rate is20sccm,too many Si-H bonds will be introduced into the device during the process,leading to the decrease of the degree of nonlinearity.Finally,the resistance model of the nonlinear laminated device is analyzed,and the nonlinear properties are studied furtherly.