相变存储单元多值存储的仿真研究
发布时间：2019-04-09 20:56
【摘要】：随着智能移动终端的崛起，消费市场需要集成度高、速度快、容量大的存储芯片。以Flash为代表的传统固态存储芯片逐渐面对微缩工艺降低可靠性等方面的问题。因此，新型存储器日益成为研发焦点，其中相变随机存储器以其读写速度快、读写次数高、微缩特性好、数据保存时间长等优势而成为下一代主流存储器技术之一。 本文主要研究相变随机存储器存储单元的多值存储机理,研究了多值存储过程中器件物理性质及相变过程，并对其进行量化及仿真计算。根据有限元法，仿真系统将主方程与材料参数结合，建立仿真模型，编制了仿真计算程序。基于幅值、脉宽以及连续脉冲的电脉冲控制存储单元和存储单元总电阻判断存储效果的研究思路，对单个存储单元的多值存储控制方法、多值存储过程、制程变差的影响以及数据保存时间方面进行了较全面的多值分析，研究了单元内部相变层相态分布及温度变化趋势，制程变差影响与相变材料自发晶化影响下的多值存储状态稳定性。 仿真实验结果表明，相变存储单元可通过单电脉冲控制幅值、脉宽的方式或连续脉冲控制脉冲数的方式实现四值存储，四种存储状态分别处于1kΩ、10k Ω、100kΩ及1M Ω数量级上。相态分析表明，存储单元总电阻与相变层与底电极接触附近区域的相态分布紧密相关，，当非晶相态覆盖住该区域时存储单元电阻大幅上升，反之则迅速下降。多值存储状态稳定性分析表明，存储过程对存储单元内部尺寸变化的敏感性不一，其中相变层厚度变化对存储状态影响较大，以致存储状态电阻分布可能出现交叠；在80℃的环境下，存储单元信息可保持10年以上且不失效。
[Abstract]:With the rise of intelligent mobile terminals, the consumer market needs memory chips with high integration, high speed and large capacity. The traditional solid-state memory chips represented by Flash are gradually faced with the problems of reducing the reliability of microscale technology. Therefore, new memory has become the focus of research and development day by day, in which phase transition random access memory has become one of the next generation mainstream memory technology because of its advantages such as high speed of reading and writing, high times of reading and writing, good characteristic of miniaturization, long data storage time, and so on. In this paper, we mainly study the multi-valued storage mechanism of the phase transition random memory cell, and study the physical properties and phase transition process of the device in the multi-valued storage process, and carry on the quantification and the simulation calculation to it. According to the finite element method, the simulation system combines the master equation with the material parameters, establishes the simulation model, and compiles the simulation calculation program. Based on amplitude, pulse width and continuous pulse, the memory cell and the total resistance of the storage unit are used to judge the storage effect. The multi-valued storage control method and the multi-valued stored procedure for a single memory cell are presented. In this paper, the influence of process variation and the time of data preservation are analyzed comprehensively, and the phase distribution and temperature change trend of phase transition layer in the cell are studied. The effect of process variation on the stability of multi-valued storage state under the influence of spontaneous crystallization of phase change materials. The simulation results show that the phase change storage cell can realize four-valued storage by means of controlling amplitude, pulse width or continuous pulse number by single electric pulse, and the four storage states are in the order of 1k 惟, 10k 惟, 100k 惟 and 1m 惟, respectively, in the order of magnitude of 1k 惟, 10k 惟, 100k 惟 and 1m 惟 respectively. The phase analysis shows that the total resistance of the storage cell is closely related to the distribution of the phase state near the contact area between the phase transition layer and the bottom electrode. When the amorphous phase state covers the region, the resistance of the memory cell increases significantly, whereas the resistance of the memory cell decreases rapidly. The stability analysis of multi-valued storage state shows that the sensitivity of stored procedure to the change of internal size of storage cell is different, and the change of phase transition layer thickness has a great influence on the storage state, so that the resistance distribution of storage state may overlap. At 80 鈩
本文编号：2455528
[Abstract]:With the rise of intelligent mobile terminals, the consumer market needs memory chips with high integration, high speed and large capacity. The traditional solid-state memory chips represented by Flash are gradually faced with the problems of reducing the reliability of microscale technology. Therefore, new memory has become the focus of research and development day by day, in which phase transition random access memory has become one of the next generation mainstream memory technology because of its advantages such as high speed of reading and writing, high times of reading and writing, good characteristic of miniaturization, long data storage time, and so on. In this paper, we mainly study the multi-valued storage mechanism of the phase transition random memory cell, and study the physical properties and phase transition process of the device in the multi-valued storage process, and carry on the quantification and the simulation calculation to it. According to the finite element method, the simulation system combines the master equation with the material parameters, establishes the simulation model, and compiles the simulation calculation program. Based on amplitude, pulse width and continuous pulse, the memory cell and the total resistance of the storage unit are used to judge the storage effect. The multi-valued storage control method and the multi-valued stored procedure for a single memory cell are presented. In this paper, the influence of process variation and the time of data preservation are analyzed comprehensively, and the phase distribution and temperature change trend of phase transition layer in the cell are studied. The effect of process variation on the stability of multi-valued storage state under the influence of spontaneous crystallization of phase change materials. The simulation results show that the phase change storage cell can realize four-valued storage by means of controlling amplitude, pulse width or continuous pulse number by single electric pulse, and the four storage states are in the order of 1k 惟, 10k 惟, 100k 惟 and 1m 惟, respectively, in the order of magnitude of 1k 惟, 10k 惟, 100k 惟 and 1m 惟 respectively. The phase analysis shows that the total resistance of the storage cell is closely related to the distribution of the phase state near the contact area between the phase transition layer and the bottom electrode. When the amorphous phase state covers the region, the resistance of the memory cell increases significantly, whereas the resistance of the memory cell decreases rapidly. The stability analysis of multi-valued storage state shows that the sensitivity of stored procedure to the change of internal size of storage cell is different, and the change of phase transition layer thickness has a great influence on the storage state, so that the resistance distribution of storage state may overlap. At 80 鈩
本文编号：2455528
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