阻变纳米硅薄膜的制备及其阻变特性的研究

发布时间：2018-05-28 14:14

本文选题：阻变存储 + nc-Si薄膜　；参考：《南京大学》2012年硕士论文

【摘要】：随着英特尔公司宣布开始量产22纳米工艺制程的芯片,集成电路的器件线宽不断减小,基于电荷存储机制的传统存储器已经遇到极大的挑战。在这个背景下,许多新型存储器被提出,其中最有希望的候选之一就是阻变存储器,而阻变存储机制的研究是当前阻变存储器的研究热点。最近,关于SiOx薄膜中"nc-Si细丝通道”引起的阻变特性的报道引起了广泛关注,同时为我们探索nc-Si薄膜的阻变特性提供了线索。nc-Si薄膜作为一类重要的硅基功能材料,在硅基光电集成方面有着重要的应用前景,对nc-Si薄膜的阻变特性的研究将对阻变材料在未来存储器中的应用有着重要的意义。本文以镶嵌在Si02基质中的nc-Si薄膜为研究对象,采用电子束蒸发法制备了SiO薄膜,通过HR-TEM研究SiO薄膜和nc-Si薄膜的微结构,用XPS分析了SiO薄膜和nc-Si薄膜的组分结构,探讨了不同的退火条件对nc-Si薄膜结构的影响。在此基础上,制备了顶电极/nc-Si薄膜／衬底的“三明治”结构样品,进而研究了不同样品制备条件下c-Si薄膜的阻变特性,分析了阻变特性的根源。基于经过擦／写操作的器件的R-TEM,提出了nc-Si细丝通道模型,并通过原子键的结构图解释了nc-Si薄膜的阻变机制。最后,研究了阻变nc-Si薄膜的介电函数特征峰,提出了以nc-Si为核心,SiOx为壳层的核壳结构,是形成nc-Si细丝通道的基本单元,为阐明阻变机制提供了有力的证据。本文的主要成果和创新点如下： (1)利用电子束蒸发制备SiO薄膜结合退火的方法制备了nc-Si薄膜。采用HR-TEM对样品进行了表征,证实了快速热退火与常规炉管式退火相结合可以得到均匀性较好的镶嵌在Si02基质中的nc-Si薄膜。根据XPS建立了SiO薄膜和nc-Si薄膜的RB_RM混合模型,阐明了原始SiO薄膜的结构特征和nc-Si薄膜的形成机制。同时,在nc-Si薄膜中观察到了由于“电荷存储效应”引起的XPS峰位漂移的现象。 (2)退火前后的样品的I-V特性的对比表明nc-Si是产生阻变特性的关键。在排除了顶电极材料对阻变特性的影响的前提下,我们证明了nc-Si薄膜是阻变特性的唯一原因。基于HR-TEM结果,使用“nc-Si细丝通道”模型解释了器件的阻变机制；建立了Si、O原子成键示意图,阐明了SiOx(?)Si的氧化还原反应和“nc-Si细丝”的“断开”与“连接”。此外,利用光刻方法减小顶电极的面积,并成功改进了nc-Si薄膜器件的阻变特性。 (3)根据SiO薄膜和nc-Si薄膜的结构模型,选取了相应的介电函数模型,研究了nc-Si薄膜结构与介电函数特征之间的关系。基于我们的纳米硅薄膜的介电函数特征峰有别于nc-Si镶嵌在Si02基质结构的特征峰,提出了以nc-Si为核心,SiOx为壳层的核壳结构,该结构将有利于nc-Si硅细丝通道的形成。并从nc-Si的尺寸、间距以及SiOx壳层的厚度解释了阻变特性与nc-Si核壳结构的关系,为阻变机制模型提供了有力的证据。
[Abstract]:With Intel's announcement that it is starting to mass-produce a 22-nanoscale process chip, the device linewidth of integrated circuits is decreasing, and the traditional memory based on charge storage mechanism has faced great challenges. In this context, many new types of memory have been proposed, among which one of the most promising candidates is resistive memory. Recently, the reports on the resistance properties of nc-Si filaments in SiOx thin films have attracted much attention, and have provided clues for us to explore the resistive properties of nc-Si thin films as a kind of important silicon-based functional materials. The research on the resistance characteristics of nc-Si thin films will be of great significance to the application of resistive materials in the future memory. In this paper, nc-Si thin films embedded in Si02 substrates were studied. SiO thin films were prepared by electron beam evaporation. The microstructure of SiO and nc-Si films was studied by HR-TEM. The composition of SiO and nc-Si films was analyzed by XPS. The effect of different annealing conditions on the structure of nc-Si films was discussed. On this basis, the "sandwich" structure samples of the top electrode / nc-Si film / substrate were prepared, and the resistance properties of the c-Si films were studied under different conditions, and the root causes of the resistance characteristics were analyzed. Based on R-TEM of erasure / write operation, the nc-Si filament channel model is proposed, and the mechanism of nc-Si film resistance is explained by atomic bond structure diagram. Finally, the dielectric function characteristic peaks of nc-Si films are studied. The core-shell structure with nc-Si as the core and Sio _ x as the shell layer is proposed as the basic unit to form the nc-Si filament channel, which provides a strong evidence for elucidating the resistance mechanism. The main achievements and innovations of this paper are as follows: 1) SiO thin films were prepared by electron beam evaporation (EBE) combined annealing. The samples were characterized by HR-TEM, and it was proved that the nc-Si films embedded in Si02 substrate with good homogeneity could be obtained by combining rapid thermal annealing with conventional furnace tube annealing. Based on XPS, the mixed RB_RM model of SiO film and nc-Si film was established, and the structure characteristics of the original SiO film and the formation mechanism of nc-Si film were elucidated. At the same time, the phenomenon of XPS peak drift caused by "charge storage effect" has been observed in nc-Si thin films. 2) the comparison of I-V characteristics of the samples before and after annealing shows that nc-Si is the key factor to produce resistance properties. On the premise of excluding the influence of the top electrode material on the resistance, we prove that the nc-Si film is the only reason for the resistance. Based on the HR-TEM results, the "nc-Si filament channel" model is used to explain the resistance mechanism of the device, and the bond diagram of Si-O atom is established, which illustrates the redox reaction of SiOx(?)Si and the "disconnection" and "connection" of "nc-Si filament". In addition, the area of the top electrode is reduced by photolithography, and the resistance characteristics of nc-Si thin film devices are improved successfully. According to the structure model of SiO film and nc-Si film, the corresponding dielectric function model is selected, and the relationship between the structure of nc-Si thin film and the characteristics of dielectric function is studied. Based on the difference between the dielectric function characteristic peak of our nanocrystalline silicon film and the characteristic peak of nc-Si embedded in the Si02 matrix structure, a core-shell structure with nc-Si as the core SiOx as shell layer is proposed, which will facilitate the formation of nc-Si silicon filament channel. The relationship between the resistance and the structure of the nc-Si core-shell is explained from the dimension, spacing and the thickness of the SiOx shell, which provides a strong evidence for the resistance mechanism model.
【学位授予单位】：南京大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：TB383.1;TP333

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