Simulation And Analysis Of 3D Xpoint Memory Based On Phase Change Unit

In recent years,the advent of 3D XPoint technology solves the storage capacity problem of phase change random access memory(PCRAM),but it also brings the problem of data storage instability caused by thermal crosstalk.In addition,as the size of the memory cells decrease to the nanometer level,the heat conduction in the memory will be greatly affected by the interface thermal contact resistance.Therefore,it is very important to analyze the thermal crosstalk of 3D XPoint memory based on phase change unit and the thermal effect of thermal contact resistance on the memory.In this thesis,the working process of memory is modeled and simulated in COMSOL Multiphysics software,including the construction of geometric model,material parameter model and boundary condition model.Then,in order to determine the voltage loading scheme adopted by the memory and whether to add strobe or not,the influence of the voltage loading scheme and OTS selectors on the energy consumption of memory is analyzed.It is found that when there are many cells in the memory array,compared with the V/3 voltage loading scheme,the V/2 voltage loading scheme can reduce the energy consumption and improve the energy utilization ratio.At the same time,the existence of a selector can also reduce the energy consumption of memory and improve the energy utilization ratio,especially the effect of strobe is more significant when there are many cells in the memory.Therefore,the V/2 voltage loading scheme is adopted in the later simulation and OTS selectors is added to the model.Furthermore,the interface thermal contact resistance module is added to the model to make the simulation model more closer to the actual storage units.The influence of thermal contact resistance on the RESET voltage and thermal crosstalk is further analyzed.It is found that the thermal contact resistance can significantly reduce the memory programming voltage,when the thermal contact resistance value increases to 40m~2K/GW,the RESET voltage decreases about 40%.Moreover,the temperature of the adjacent units of the selected unit decreases with the increase of the thermal contact resistance,which greatly alleviates the problem of thermal crosstalk.Then,the material parameters and the structural parameters of the phase change unit are analyzed under the condition of different thermal contact resistance,and the influence of thermal crosstalk on the memory is summarized,which provides a detailed basis for optimizing the design of 3D XPoint memory based on the phase change unit.