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基于中芯国际40 nm工艺制备的64 Mbit相变存储器,设计并进行了两组对比实验。分别使用不同幅值和脉宽的RESET电流脉冲对存储器单元进行疲劳操作,对相变存储器单元的疲劳性能与RESET操作电流的关系进行了研究。实验结果表明,存储单元的疲劳寿命和RESET脉冲幅值的平方呈反比关系,和脉冲宽度呈反比关系。在相变存储器的操作过程中,高阻态下的电阻值出现先减小后增大的漂移现象,这是因为操作电流会对相变材料组分产生影响,在相变材料层中会出现逐渐增大的孔洞,孔洞最终导致相变器件失效,与实验中高阻态阻值漂移现象相吻合,同时可以用来预测存储单元的疲劳寿命。
Based on SMIC’s 64-nm phase-change memory, SMIC designs and conducts two comparative experiments. The RESET current pulses with different amplitudes and pulse widths are used respectively to fatigue the memory cell, and the relationship between the fatigue performance of the phase change memory cell and the RESET operating current is studied. The experimental results show that the fatigue life of memory cells is inversely proportional to the square of the RESET pulse amplitude, and inversely proportional to the pulse width. During phase-change memory operation, the resistance value in high-impedance state first decreases and then increases. This is because the operating current will affect the phase-change material composition and will appear in the phase-change material layer Increasing voids and voids eventually lead to the failure of phase change devices, coinciding with the high-state resistance drift in experiments and can be used to predict the fatigue life of memory cells.