Diamond Film Deposition in a Radio-Frequency Thermal Plasma

在已经证明的金刚石薄膜的化学气相沉积(CVD)方法中，射频热等离子体方法是最有前途的方法之一，因为它沉积速度快，无污染，并且在大的衬底面积上具有良好的薄膜一致性。本工作旨在发展对射频热等离子体反应器中金刚石薄膜化学气相沉积机理的基本了解，并利用这种了解来确定工艺条件，从而能够在各种工业感兴趣的衬底上高速沉积高质量的金刚石薄膜。将进行实验，以表征可控工艺参数对薄膜性能和沉积速率的影响。使用光学热法、激光诱导荧光和用探针收集的样品的气相色谱，可以在线测量邻近衬底的边界层和衬底表面的温度和化学物种浓度。沉积薄膜的分析将通过光学显微镜、扫描电子显微镜、拉曼光谱和X射线衍射获得。与实验研究并行开发的数值模型将专门对应于实验反应器和条件，并预测薄膜生长速度作为工艺变量的函数。在机械、热、光学、电学和声学性能方面，钻石是一种最好的材料。在各种衬底(各种材料和形状)上沉积金刚石薄膜是一个快速增长的领域，在机床、磨料、轴承、激光、透镜/反射镜和微电子设备等领域具有潜在的巨大市场。在高沉积速率下生产均匀的纯金刚石涂层的能力对这一领域的未来发展至关重要。该项目代表了探索射频热等离子体方法进行此类生产的重要一步，并将进一步促进射频热等离子体CVD工艺的其他潜在应用的知识和技术基础。

Among the processes which have been demonstrated for chemical vapor deposition (CVD) of diamond films, the radio-frequency thermal plasmas approach is one of the most promising in terms of high deposition rates, lack of contamination, and good film uniformity over large substrate areas. The present work is directed at development of a fundamental understanding of the mechanisms of diamond-film CVD in an rf thermal plasma reactor and use of that understanding for definition of process conditions which will enable high-rate deposition of high- quality diamond films on various substrates of industrial interest. Experiments will be conducted to characterize the effects of controllable process parameters on film properties and deposition rates. On-line measurements of temperatures and chemical species concentrations in the boundary layer adjacent to the substrate and at the substrate surface itself will be obtained using optical pyrometry, laser-induced fluorescence, and gas chromatography of samples gathered with probes. Analyses of the deposited films will be obtained from optical microscopy, scanning electron microscopy, Raman spectroscopy, and X-ray diffraction. A numerical model which specifically corresponds to the experimental reactor and conditions and which predicts film growth rates as a function of process variables will be developed in parallel with the experimental studies. Diamond is a superlative material with respect to mechanical, thermal, optical, electrical, and acoustic properties. Deposition of diamond films on various substrates (various materials and shapes) is a rapidly growing field with a potentially huge market in such areas as machine cutting tools, abrasives, bearings, lasers, lenses/mirrors, and microelectronic devices. The ability to produce uniform pure diamond coatings at high deposition rates is critical to future developments in this area. This program represents an important step in exploration of the rf thermal plasma approach to such production, and will additionally advance the knowledge and technology base for other potential applications of rf thermal plasma CVD processes.