Fabrication And Performance Analysis Of Superlattice Electrodes For Low-power Phase Change Memory

Phase Change Memory(PCM)is considered to be the most potential next-generation computer storage device,due to the advantages of high storage density,long cycle life and fast reading and writing speed.However,due to the high thermal conductivity of many materials(TiN,W,etc.)used as PCM electrodes at this stage.The PCM caused a large amount of heat loss in the electrode direction during the working process,thereby causing the large power consumption problem of PCM to be increasingly serious.To solve this problem,this paper first analyzes in detail the effect of superlattice structure on the thermal conductivity of materials,and based on TiN and W,two commonly used electrode materials for PCM.TiN/W superlattice electrodes with lower thermal conductivity are fabricated by magnetron sputtering process,so as to solve the problem of large power consumption and heat dissipation caused by PCM electrodes.The specific research contents are as follows.Firstly,aiming at the problem that traditional electrode materials such as TiN and W have high thermal conductivity,according to the micro regulation mechanism of superlattice structure on material thermal conductivity,the heat transfer simulation model of PCM based on TiN/W superlattice electrode is built in the simulation software.The simulation results show that,the TiN/W superlattice electrode can effectively suppress the heat loss of PCM along the electrode direction due to its lower thermal conductivity.The low heat loss makes the Reset voltage of the PCM in the Reset process reduced by 10% and 13% compared with the traditional TiN and W single-layer electrodes,resulting in the reduction of the operating power consumption of the PCM.Then,based on magnetron sputtering,the fabrication process and parameters meeting the experimental requirements are designed,the fabrication of TiN/W superlattice electrode is completed,and its performance is characterized and tested.Firstly,by studying the effects of process parameters such as background vacuum,sputtering power,substrate temperature and substrate table speed on the thickness and resistivity of TiN and W single-layer films,the process flow of TiN/W superlattice electrode is designed,and the superlattice electrodes with different thickness of 120 nm and 60 nm are fabricated.In addition,detailed characterization and performance analysis of TiN/W superlattice electrodes is launched by SEM,fourth probes,and 3ω method.The cross-sectional characterization results of SEM show that,the total thickness of the two TiN/W supercrystal electrodes fabricated in this paper are 123.6nm and 64.2nm,with obvious delamination and uniform interface.The resistivity test results of four probes show that,the resistivity of the above two TiN/W superlattice electrodes are 877.6μΩ·cm and 770μΩ·cm.The thermal conductivity test results of the 3ω method show that,the thermal conductivity of the above two TiN/W superlattice electrodes are 1.682W/(m·k)and0.721W/(m·k).Compared with TiN and W single layer thin films,the thermal conductivity of TiN/W superlattice electrode has been reduced by an order of magnitude.The experimental and test results show that,the TiN/W superlattice electrode is successfully fabricated in this paper,and it also proves that the superlattice structure can reduce the thermal conductivity of the material.