基于刀片型限制结构的相变存储器阵列的热串扰效应研究

Thermal Disturbance Effect of Phase Change Random Access Memory Array Based on Blade-Type Structure

大数据时代的到来,对高密度存储和计算的速度、功耗提出了更高的要求.相变存储器由于具有较短的读取延迟和良好的可扩展性,在存储和计算领域中具有广阔的应用前景.将相变存储器扩展为高密度存储阵列时所产生的热串扰现象是目前阵列集成所面临的重要挑战,而热串扰所产生的干扰热量会进一步传递到相邻单元并使其发生误操作,导致存储器阵列的可靠性、准确性和稳定性受到影响.因此,本文针对一种新型刀片型结构的3×3相变存储器阵列在激活状态下的热串扰现象进行了系统研究,通过仿真计算软件Comsol Multiphysics系统研究了新型刀片型结构的相变存储器阵列对热串扰的敏感性,并探讨了器件单元间距、器件结构尺寸、编程脉冲以及阵列的缩放效应对存储器阵列在工作时所产生的热串扰效应及其功耗的影响.研究结果显示:基于新型刀片型结构的相变存储器阵列,即使将其缩放到20 nm的技术节点,在5 nm的器件单元间距下仍可保持较低的最大热串扰温度.此外本文对阵列单元外部的绝缘层材料进行了改进,通过使用较高热导系数的AlN薄膜来代替SiO_(2)薄膜,在存储器阵列功耗几乎保持不变的情况下进一步有效抑制了热串扰效应,使其最大热串扰温度下降了12.3%.该研究成果对未来基于相变存储器的高密度存储和计算阵列的集成具有非常重要的指导意义.

With the advent of the era of big data,higher requirements are put forward for high density storage,computing speed and power consumption.Phase-change random access memory(PCRAM)has been considered as one of the most promising candidates for future non-volatile storage applications due to its short-read delay and good scalability.The high-density integration of memory array is indispensable for its rapid commercial applications.The thermal disturbance(TDB)effect caused by the expansion of PCRAM cell into high density storage array is an important challenge for array integration.The interference heat generated will be further transferred to the adjacent cells to make them operation mistake and affect their reliability,accuracy and stability of the storage array.Therefore,in this paper,the TDB effect of a 3×3 PCRAM array that is based on a new blade-type structure is systematically studied by using Comsol Multiphysics simulation software.We further discuss the relationship between the TDB effect and the space of storage cell,the size of device structure,the programming pulse and the scaling effect of PCRAM array.The results show that even when a blade-type structure based PCRAM array is scaled to a 20 nm technology node,the effect of TDB still remains low at a 5 nm device cell spacing.In addition,we optimize the insulating layer material outside the cell device by using AlN film with higher thermal conductivity than SiO_(2) film.The TDB is further effectively suppressed while the power consumption of PCRAM array is basically unchanged,and the maximum temperature of TDB decreases by 12.3%.This work has very important guiding significance for the integration of high-density storage PCRAM arrays in the future.