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膜厚均匀性是评价光学薄膜的重要标准之一。膜厚均匀性不好,膜系特性就会遭到严重破坏。作为用于光学薄膜的主要低折射率材料,SiO2导热性很弱,且以升华的方式进行蒸发,具有特殊的蒸发特性,导致在利用电子束加热蒸发方式镀膜的过程中,膜厚分布会发生明显变化,从而严重影响薄膜质量。为了分析SiO2材料蒸发特性对膜厚均匀性的影响,对电子束焦斑热量分布进行了计算模拟,据此得到蒸发质量的分布。根据蒸发质量分布和蒸发源表面各点蒸发角的变化,计算了蒸发源在空间球面和空间平面上的分布。根据分析结果,总结了SiO2材料蒸发特性对膜厚均匀性产生影响的原因及膜厚分布的特点,为调整和改进SiO2材料镀膜工艺提供参考。
Film thickness uniformity is one of the most important criteria for evaluating optical films. Film thickness uniformity is not good, the film characteristics will be severely damaged. As a main low refractive index material for optical thin films, SiO2 has a very low thermal conductivity and evaporates in a sublimation manner, and has a special evaporation characteristic, which causes a film thickness distribution to occur during coating by electron beam heating and evaporation Significant changes, which seriously affect the quality of the film. In order to analyze the influence of SiO 2 evaporation characteristics on the uniformity of film thickness, the heat distribution of electron beam focal spot was calculated and simulated, and the distribution of evaporation mass was obtained. According to the distribution of evaporation mass and the change of evaporation angle at each point of the evaporation source, the distribution of evaporation source on the spatial sphere and the space plane was calculated. According to the analysis results, summarizes the reason why the evaporation property of SiO2 material has an influence on the uniformity of the film thickness and the characteristics of the film thickness distribution, so as to provide reference for adjusting and improving the SiO2 material coating technology.