高功率MPCVD法制备高质量金刚石膜的研究

发布时间：2018-05-18 01:10

本文选题：微波等离子体 + 化学气相沉积　；参考：《武汉工程大学》2015年硕士论文

【摘要】：CVD金刚石膜因其优异的物理化学性能,使得其在众多领域具有广泛应用。特别是在军事领域,高质量光学级金刚石膜一直是各个科研团队研究的重点。而在诸多人造金刚石膜方法中,微波等离子体化学气相沉积法被认为是制备高质量CVD金刚石膜的理想方法,然而目前主要制约高质量金刚石膜因素有设备的研制及工艺参数调试。本论文在实验室前期研究的基础上,应用韩国Woosinent公司R2.0-MPCVD沉积系统以及实验室自制的20kW-MPCVD装置,系统研究了各项工艺参数对高质量金刚石膜的制备影响。主要研究如下:1、采用微波等离子体化学气相沉积技术,以Ar/CH4/H2为气源,在较高等离子体密度下,通过改变不同表面预处理方法,研究了预处理方法对纳米金刚石的生长影响。实验表明,形核密度的大小与表面预处理方法密切相关,形核密度越高,所制备的纳米金刚石膜越光滑。当采用预处理两步法,即先用等离子体进行处理,随后用含有纳米金刚石粉的溶液进行超声震荡,所获得的纳米金刚石膜的晶粒尺寸大约在27.5nm。另外,纳米金刚石膜的晶粒尺寸与衬底表面预处理方法和粗糙度密切相关,表明衬底表面具有轮廓遗传效应。2、应用装置独特的基片加热系统,通过控制甲烷浓度和基片温度,在较低的工作气压下,实现了高质量高取向(100)面金刚石膜的可控性生长。实验表明,为了获得相似的高取向(100)面金刚石膜,在升高基片温度的同时,也需要相应的增加甲烷浓度;在金刚石膜生长过程中,碳源浓度和基片温度表现出一种耦合作用,且该作用较大,通过选择合适的碳源浓度和基片温度,可以沉积出具有高取向(100)面金刚石膜,且重复性较好。但是为了制备出高质量高取向(100)面金刚石膜,应当选择合适的甲烷浓度和基片温度。3、在较高等离子体密度下系统研究了辅助气体对金刚石膜形貌、膜品质以及生长率的影响;单纯以甲烷/氢气为气源时,晶面生长取向以(100)面为主,晶粒空隙较大,膜中非金刚石碳相较多;适量引入氧气或二氧化碳有利于减少金刚石膜的杂质,促进其生长;引入氮气时生成典型的“菜花状”结构,而引入氩气时生成具有纳米尺寸的“米粒状”;引入氮气或氩气时,金刚石膜的质量会呈现出下降趋势;同时在分别引入氮气或氩气辅助气体时,所沉积的金刚石膜具有微纳米双层膜结构。4、通过新工艺,在辅助气体二氧化碳参与下制备出了高质量微/纳米双层金刚石膜,研究表明为得到较高品质的微/纳米双层金刚石膜,同时又要具有较高生长率,二氧化碳浓度不宜使用太低或太高,在本文中,其浓度在2.5%时较佳。
[Abstract]:CVD diamond films have been widely used in many fields because of their excellent physical and chemical properties. Especially in the military field, high-quality optical grade diamond films have been the focus of various research teams. Among many synthetic diamond films, microwave plasma chemical vapor deposition (MPCVD) is considered to be an ideal method for the preparation of high quality CVD diamond films. However, the main factors restricting the high-quality diamond film are the development of equipment and the adjustment of process parameters. Based on the previous research in laboratory, the effects of various technological parameters on the preparation of high quality diamond films have been systematically studied by using the R2.0-MPCVD deposition system of Woosinent Company of Korea and the self-made 20kW-MPCVD device of the laboratory. The effects of different surface pretreatment methods on the growth of nanocrystalline diamond were studied by using microwave plasma chemical vapor deposition (MPCVD) and Ar/CH4/H2 as gas source under high plasma density. The results show that the nucleation density is closely related to the surface pretreatment method, and the higher the nucleation density is, the more smooth the nanocrystalline diamond films are prepared. When the pre-treatment was carried out by two steps, plasma was used first, and then the solution containing nano-diamond powder was used for ultrasonic oscillation, the grain size of the nanocrystalline diamond film was about 27.5 nm. In addition, the grain size of the nanocrystalline diamond film is closely related to the pretreatment method and roughness of the substrate surface, which indicates that the substrate surface has a contour genetic effect .2. the unique substrate heating system is used to control the concentration of methane and the substrate temperature. The controllable growth of high quality and high orientation diamond film was realized at low working pressure. The experimental results show that in order to obtain similar diamond films with high orientation and high orientation, it is necessary to increase the concentration of methane at the same time as the substrate temperature, and the carbon source concentration and substrate temperature show a coupling effect during the growth of diamond films. By choosing the appropriate concentration of carbon source and substrate temperature, diamond films with high orientation can be deposited, and the reproducibility is good. However, in order to prepare high quality and high orientation diamond film, the influence of auxiliary gas on the morphology, film quality and growth rate of diamond film should be studied at high plasma density by selecting appropriate methane concentration and substrate temperature. When methane / hydrogen is used as the gas source, the crystal plane grows mainly on the surface of 100), with large grain voids and more non-diamond carbon phase in the film, and the proper amount of oxygen or carbon dioxide can reduce the impurity and promote the growth of the diamond film. A typical "cauliflower" structure is formed when nitrogen is introduced, while "rice grain" with nanometer size is formed when argon is introduced, and the quality of diamond film decreases when nitrogen or argon is introduced. At the same time, when nitrogen or argon assisted gas is introduced, the diamond film has a micro-nanometer double-layer structure of .4.The high quality micro-/ nano-bilayer diamond film has been prepared with the help of carbon dioxide as the auxiliary gas through the new process. The results show that in order to obtain high quality micro-/ nano-bilayer diamond films and have high growth rate, the concentration of carbon dioxide should not be used too low or too high. In this paper, the concentration of carbon dioxide is better when the concentration is 2.5.
【学位授予单位】：武汉工程大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ163;TB383.2

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