氧基阻变存储器阻变机理和耐久性失效研究

发布时间：2018-05-18 11:55

本文选题：非挥发性存储器 + 氧基阻变存储器　；参考：《山东大学》2013年硕士论文

【摘要】：近年来,随着智能手机、平板电脑、移动存储等一系列高科技产品在人们生活中普及,非挥发性存储器扮演着越来越重要的角色。然而,随着工艺节点不断向前推进,当前主流的基于浮栅结构的非挥发性存储器Flash开始遇到严重的技术瓶颈。针对这一情况,国内外纷纷开展对下一代新型存储技术的研究。其中,阻变存储器以其速度快、功耗低、与传统CMOS工艺相兼容等特点,被认为是下一代非挥发性存储器的有力竞争者。然而,阻变存储器还存在着很多问题,诸如：阻变机理不是足够清晰,电学参数均一性不高等。本论文选择结构简单、性能相对稳定的以HfO2作阻变材料的氧基阻变存储器作为研究器件,开展关于阻变机理和耐久性失效的相关研究工作。首先,通过调整制备器件的工艺参数,以及器件阻变层和储氧层的厚度,制备得到了性能指标相对理想的氧基阻变器件,结构为W/Ti/HfO2/Pt。利用半导体参数分析仪对阻变器件的电学性能进行测试,分析了器件编程、擦除、循环操作等过程的电学性能。对1900次编程擦除循环的编程电压、编程电流进行统计学分析,推断编程过程的物理本质,得到了影响阻变过程的最直接因素是电场而不是电流的结论,电流引起的热效应并不是本研究器件主要的阻变影响因素。这为之后的阻变机理模型的提出奠定了基础。提出了电场控制下的基于氧离子Hopping理论的阻变模型,对电场作用下氧离子迁移的物理过程进行了深刻剖析。利用提出的阻变机理模型进行推导计算,得出了擦除时间和所加电场之间的关系,并进行分析。此外,还计算了温度对擦除时间和所加电场关系的影响。设计实验,利用脉冲发生器和示波器对器件的擦除时间进行测试,得到了施加不同电场下的擦除时间,并发现实验值与利用模型推导出的理论值很好地吻合,说明了所提出模型的正确性。根据氧基阻变器件的整个循环操作直至失效所表现出的电学性能特点,对器件耐久性失效情况进行了分析,提出了耐久性失效的两个原因：氧离子流失和氧化层的负向击穿。并设计对比实验,研究了退火处理对阻变存储器负向击穿电压的影响,得到了一种提高器件耐久性能的方法。
[Abstract]:In recent years, with the popularity of a series of high-tech products, such as smart phones, tablets, mobile storage and so on, non-volatile memory plays an increasingly important role. However, with the continuous progress of the process nodes, the current mainstream non-volatile memory Flash based on floating gate structure begins to encounter serious technical bottlenecks. In response to this situation, domestic and foreign research on the next generation of new storage technology has been carried out. Because of its high speed, low power consumption and compatibility with the traditional CMOS process, resistive memory is considered to be a strong competitor for the next generation of non-volatile memory. However, there are still many problems in resistive memory, such as: the mechanism of resistance is not clear enough, and the uniformity of electrical parameters is not high. In this thesis, a simple structure and relatively stable performance of oxygen based resistance memory (ORAM) with HfO2 as the resistive material is chosen as the research device, and the related research work on the resistance mechanism and durability failure is carried out. Firstly, by adjusting the process parameters of the fabricated devices and the thickness of the resistive layer and the oxygen storage layer, the oxygen based resistive devices with relatively ideal performance indexes are prepared. The structure is W / Ti / HfO _ 2 / Pt. The electrical properties of resistive devices are tested by using semiconductor parameter analyzer. The electrical properties of device programming, erasure and cycle operation are analyzed. The programming voltage and current of the erasure cycle for 1900 times are analyzed statistically, the physical essence of the programming process is inferred, and the conclusion that the most direct factor affecting the resistive process is the electric field rather than the current is obtained. The thermal effect caused by current is not the main factor of resistance. This lays a foundation for the later model of resistance mechanism. A resistive model based on oxygen ion Hopping theory is proposed under the control of electric field, and the physical process of oxygen ion migration under the action of electric field is deeply analyzed. The relationship between the erasure time and the applied electric field is derived and calculated by using the proposed resistance mechanism model, and the relationship between the erasure time and the applied electric field is analyzed. In addition, the effect of temperature on the erasure time and the applied electric field is also calculated. The erasure time of the device is tested by pulse generator and oscilloscope, and the erasure time under different electric field is obtained. It is found that the experimental value is in good agreement with the theoretical value derived from the model. The correctness of the proposed model is explained. According to the electrical characteristics of the whole cycle operation and failure of the oxygen based resistor device, the durability failure of the device is analyzed, and two reasons for the durability failure are put forward: the oxygen ion loss and the negative breakdown of the oxide layer. The effect of annealing treatment on the negative breakdown voltage of the resistive memory is studied and a method to improve the durability of the device is obtained.
【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TP333

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