Simulation Study Of Resistance Drift Based On PCNE Multi-level Storage

Phase change random access memory has the advantages of fast read and write speeds,many cycles of erasing and writing,large storage capacity,and compatibility with CMOS technology.It meets the needs of people for storing large amounts of data.Its basic component – Phase Change Nanometer Element(PCNE)has a multi-level storage function,which can further increase storage density and reduce costs,but the PCNE multi-level storage function is greatly affected by resistance drift.Therefore,it is of great significance to study the resistance drift under the PCNE multi-level storage function.Based on the working principle of PCNE,this thesis used the finite element method to build a simulation system for PCNE(mainly including electrical,thermal,phase and resistance drift simulation modules).According to the temperature and phase distribution in PCNE,firstly,the resistance drift during RESET was simulated,the effect of resistance drift on the multi-level storage function was analyzed;secondly,the reason why the resistance drift coefficient reaches saturation was explored;finally,the influence of PCNE structural parameters(size of the lower heating electrode,thickness of the phase change material GST)on the resistance drift was studied.The simulation results show that:(1)Due to the large drift of the amorphous resistance and the small drift of the crystalline resistance,during the RESET process,as the phase change material GST amorphous ratio gradually increases,the drift of the resistance gradually increases large,the range of the resistance drift coefficient is 0.014 ? 0.11;(2)The reason why the resistance drift coefficient reaches saturation during the RESET process is that the GST amorphous state completely covers the heated electrode;(3)The smaller the size of the lower heating electrode,the greater the rate of change of the resistance drift coefficient before the amorphous GST covers the lower heating electrode;(4)The larger the GST thickness,the smaller the rate of change of the resistance drift coefficient before the amorphous GST covers the lower heating electrode.