硅基高κ介质阻变存储器的制备工艺与特性

发布时间：2018-07-22 11:38

【摘要】：半导体逻辑器件和存储器件是集成电路中最重要的两个部分。近年来,随着集成电路工艺的发展,半导体存储器件的特征尺寸已经缩小到30nm以下。在器件尺寸减小和工艺改进的同时,也带来了新的材料、结构和物理问题。为了提高存储器件的性能,寻找可以替代动态随机读写存储器和闪存等现有的器件,目前国际上正在研究多种新型器件,包括铁电存储器、磁阻存储器、相变存储器以及阻变存储器(RRAM)。其中,RRAM由于结构简单、读写速度快、功耗低以及与现有CMOS工艺兼容等优点受到了极大的关注。目前,RRAM研究中存在的最大问题是它的导电机理。由于RRAM使用的材料和结构多样性,实验中观察到的器件性能也不尽相同,因此,国际上提出了多种不同的导电机理和相关模型,但是还缺乏一种普适模型,可以很好指导器件的开发和改进。另外,近年发现一些RRAM结构中存在整流特性,这一特性在器件应用中具有重要意义,可以简化RRAM的电路结构。但是,目前我们对整流效应的机理和器件结构的关系还缺乏深入地了解。第三,对器件的应用而言,结构和特性的优化,以及器件的可靠性等是非常重要的,还需要大量的进一步的研究。针对目前RRAM中存在的关键问题,本论文研究硅基高K介质RRAM的制备工艺与特性,包括导电机理、整流特性、温度特性、面积特性、噪声特性和结构优化。具体有：(1)制备了具有不同面积、不同高K介质材料和金属电极的RRAM样品。 (2)对样品进行了电学测量和分析,包括不同温度下的阻态转换和整流等Ⅳ特性,随机电报噪声和1/f噪声特性。(3)提出了一种新的RRAM导电机理和相关等效电阻模型,通过模型与实验结果的比较,提出了一个对应的RRAM工作能带图。本论文的创新结果有：(1)我们发现RRAM的总电阻是由半导体/介质界面、介质层和介质/金属界面三个电阻串联构成,在不同的工作条件和阻态下,各个电阻对Ⅳ特性具有不同的影响。(2)在RRAM的导电机理分析中,我们发现电子的输运需要声子辅助。利用声子辅助模型,所有实验结果能够得到很好地解释。(3)由上述等效电阻模型和声子辅助模型,能够很好解释我们在硅基高k介质RRAM中观察到的整流特性。(4)我们分别对1/f噪声和随机电报噪声特性进行了测量,并对实验结果进行了详细讨论。上述结果,对深入了解RRAM的工作机理,指导器件结构和特性的改进和优化,’促进这一存储器件的开发和应用具有重要的意义。
[Abstract]:Semiconductor logic devices and memory devices are the two most important parts of integrated circuits. In recent years, with the development of integrated circuit technology, the characteristic size of semiconductor memory device has been reduced to below 30nm. At the same time, new material, structure and physical problems are brought along with the reduction of device size and process improvement. In order to improve the performance of memory devices and to find alternatives to existing devices such as dynamic random read / write memory and flash memory, many new types of devices are being studied in the world, including ferroelectric memory and magnetoresistive memory. Phase change memory and resistive memory (RRAM). Due to its simple structure, high speed of reading and writing, low power consumption and compatibility with the existing CMOS process, RRAM has attracted much attention. At present, the biggest problem in the research of RRAM is its conductive mechanism. Due to the diversity of materials and structures used in RRAM, the properties of the devices observed in the experiment are different. Therefore, many different conductive mechanisms and related models have been proposed in the world, but there is still a lack of a universal model. It can be used to guide the development and improvement of devices. In addition, in recent years, some RRAM structures have been found to have rectifier characteristics, which is of great significance in the application of devices, and can simplify the circuit structure of RRAM. However, we do not have a thorough understanding of the mechanism of rectifier effect and the structure of the device. Thirdly, the optimization of structure and characteristics, and the reliability of the device are very important for the application of the device, and need a lot of further research. Aiming at the key problems existing in RRAM, the preparation process and characteristics of silicon based high K dielectric RRAM are studied in this paper, including conductive mechanism, rectifying characteristic, temperature characteristic, area characteristic, noise characteristic and structure optimization. The main results are as follows: (1) RRAM samples with different area, high K dielectric materials and metal electrodes were prepared. (2) the electrical measurement and analysis of the samples are carried out, including the characteristics of resistance state conversion and rectifier at different temperatures, random Telegraph noise and 1 / f noise. (3) A new RRAM conductive mechanism and a related equivalent resistance model are proposed. By comparing the model with the experimental results, a corresponding RRAM working band diagram is proposed. The innovative results of this thesis are as follows: (1) We find that the total resistance of RRAM is composed of semiconductor / dielectric interface, dielectric layer and dielectric / metal interface in series. (2) in the analysis of the conduction mechanism of RRAM, we find that the transport of electrons needs phonon assistance. Using the phonon-assisted model, all the experimental results can be explained well. (3) based on the above equivalent resistance model and the phonon-assisted model, It can explain the rectifying characteristics observed in silicon based high k dielectric RRAM. (4) We have measured the characteristics of 1 / f noise and random Telegraph noise respectively and discussed the experimental results in detail. The above results are of great significance in understanding the working mechanism of RRAM, guiding the improvement and optimization of the structure and characteristics of RRAM, and promoting the development and application of this memory device.
【学位授予单位】：复旦大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TP333

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