The impact of heater-recess and load matching in phase change memory mushroom cells
The impact of heater-recess and load matching in phase change memory mushroom cells
复制标题
相变记忆蘑菇电池中加热器凹槽和负载匹配的影响
作者：
A. Cywar;Jing Li;C. Lam;H. Silva
使用具有旋转对称性的二维有限元模拟来分析底部电极凹陷对具有蘑菇单元几何形状（在图案化的TiN柱上的Ge2Sb2Te5（GST）膜）的相变存储器元件的复位操作的影响。对GST和TiN采用了与温度相关的材料参数，并将GST熔化过程中的熔化潜热纳入熔化模型。本研究的结果表明，一个较低的复位电流和更有利的热分布可以通过延长GST的有源区向下进入柱，由于热约束。它示出，通过电池的电流与最大功率传输的负载条件不足，可以保持在一个水平低于这是足够的复位操作延长的时间段，由于GST的温度相关的电导率的非线性性质。这些结果表明，如果负载条件不匹配，则需要过大的电压电平或脉冲持续时间来实现跨单元阵列的成功复位操作。
Two-dimensional finite element simulations with rotational symmetry are used to analyze the impact of the bottom electrode recess on the reset operation of phase change memory elements with mushroom cell geometry (Ge2Sb2Te5 (GST) film over a patterned TiN pillar). Temperature dependent materials parameters are used for GST and TiN, and the latent heat of fusion in melting of GST is included to model melting. The results of this study indicate that a lower reset current and a more favorable thermal profile may be achieved by extending the active region of GST down into the pillar, due to the heat confinement. It is shown that the current through cells with an insufficient load condition for maximum power transfer can be maintained at a level lower than that which is sufficient for reset operation for extended periods of time due to the non-linear nature of temperature dependent electrical conductivity of GST. These results suggest that if the load condition is not matched, excessive voltage levels or pulse durations would be necessary to achieve successful reset operation across cell arrays.