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题名	镀膜过程真空室气氛分布研究
作者	郑如玺
学位类别	硕士
答辩日期	2016
授予单位	中国科学院上海光学精密机械研究所
导师	易葵
关键词	HfO2薄膜 充氧口位置 k-ε模型 数值模拟 蒸发分布
其他题名	Atmosphere distribution of the vacuum chamber in coating process
中文摘要	在高功率激光材料中，氧化物薄膜是非常重要的一类。采用电子束热蒸发制备氧化物薄膜时，靶材可以选用金属氧化物、纯金属或低价金属氧化物。由于在电子束热蒸发沉积的过程中温度很高，金属氧化物一般都会出现失氧现象，所以不管选用何种靶材，都要在镀膜过程中充入适量氧气，使真空室内保持一定的氧气浓度。真空室内氧气的分布将对薄膜的性能造成重要影响。所以，研究分析镀膜过程真空室的气氛分布具有重要意义。本文围绕电子束反应蒸发镀膜过程的气氛分布问题，分别从以下几个方面开展了研究工作： 根据镀膜机构造，建立计算模型，运用计算流体力学的方法模拟计算了两种不同的边界条件下真空室内的氧气分布。 根据得到的计算结果，对比分析，得出质量入口边界条件比压力入口边界条件更适合模拟镀膜过程气氛分布的结论。 研究了两个典型的充氧口位置对电子束反应蒸发沉积HfO2薄膜性质的影响。 充氧口位置直接影响了真空室内的氧气分布，进而对薄膜的光学性能造成重要影响。选取两个典型的充氧口位置采用电子束蒸发技术在石英基底上沉积了HfO2单层膜，并结合紫外-可见分光光度计和X射线光电子能谱仪研究了不同充氧口位置下制得的HfO2薄膜的光学性能和化学成分。实验结果表明，将充氧口设置在基片附近更有利于得到致密性好、充分氧化的HfO2薄膜。根据实际真空室的构造建立简化的模型，应用k-ε二方程湍流模型对镀膜过程中的氧气分布进行了三维数值模拟计算，模拟计算的结果很好地解释了实验结果。 基于Knudsen余弦定律建立镀膜过程稳态时蒸发分子的空间密度分布，并根据得到的蒸发分子的空间密度分布结合自由程理论分析了镀膜过程与蒸发分子相关的碰撞过程。在电子束反应蒸发镀膜的过程中，存在多种粒子之间的碰撞，这些粒子之间的碰撞将会对薄膜性能的造成重要影响。研究结果表明：当沉积速率达到一定值后，在蒸发源表面附近蒸发分子之间存在碰撞，这可能会导致膜层中出现大的颗粒，影响膜层质量；蒸发分子与电子之间的碰撞会使蒸发分子离化，提高基片上氧化反应速率；碰撞分析表明，只有在基片表面具备充分反应的条件。
英文摘要	The oxide film was a very important category of the high-power laser materials. Metal oxide, pure metal or low-cost metal oxide could all be used as the target materials when the oxide films were deposited by electron beam technology. Since temperature was too high during the electron-beam deposition process, the metal oxide usually lost oxygen. So oxygen was filled in vacuum chamber in the coating process. The distribution of oxygen in the vacuum chamber would have a significant effect on the properties of the films. Therefore, research on atmosphere distribution of vacuum chamber through coating process was of great significance. In this paper, researches have been carried out on the following aspects: Calculation model was built according the sketch of vacuum chamber. We used the method of computational fluid dynamics to calculate the distribution of oxygen under two different boundary conditions. According to the results obtained, the quality of mass inlet boundary condition was more suitable for the simulation of coating process than the pressure inlet boundary conditions conclusion. Influence of two typical oxygenating port position on the properties of HfO2 films was studied. Oxygenating port position directly affected the distribution of oxygen in the vacuum chamber, which resulted in a significant impact on the performance of the film. To study the influence of oxygenating port position on the properties of HfO2 films, the HfO2 films were deposited on the silica substrates by electron beam technology at two typical oxygenating port position. Influence of oxygenating port position on the properties of HfO2 films was investigated with ultraviolet-visible spectrophotometer and X-ray photoelectron spectrometer. The experimental results showed that providing oxygenating port in the vicinity of the substrate was more conducive to obtain good compactness and full oxidation of HfO2 films. A simplified model was established according to the configuration of the actual vacuum chamber. The turbulence models of k-ε quadratic equation was applied to carry on three-dimensional numerical simulation calculation on the distribution of oxygen in the coating process. The theory calculation fitted well with the experimental results. Spatial density distribution of evaporated molecules during coating process was established based on Knudsen cosine law. Mean free path theory was applied to carry on analysis of the collision process associated with evaporated molecules. There were multiple collisions between the particles of the vacuum chamber during the electron-beam deposition process. These collisions would have a significant impact on the properties of the film. The collision of evaporated molecules might result in a large particle layer appears large particles in the film. The collisions between evaporated molecules and electrons might cause ionization of the evaporated molecules, which would increase the rate of the oxidation reaction on the substrate.
语种	中文
内容类型	学位论文
源URL	[http://ir.siom.ac.cn/handle/181231/16998]
专题	上海光学精密机械研究所_学位论文
推荐引用方式 GB/T 7714	郑如玺. 镀膜过程真空室气氛分布研究[D]. 中国科学院上海光学精密机械研究所. 2016.

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