SiO2材料蒸发特性对膜厚均匀性的影响

Impact of Evaporation Characteristics of SiO_2 on Uniformity of Thin-Film Thickness

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。

Uniformity of thin-film thickness is one of the main standards of judging optical thin film.The bad uniformity of thin film can damage the characteristics of costing system.As a main material of low refractive index to preparation of optic thin film,SiO2 is poor thermal conductivity and sublimes.The particularity of evaporation characteristic of SiO2 leads to obvious change of thin film thickness when SiO2 is evaporated by e-beam method,which affects the quality of thin film heavily.For the purpose of analyzing the impacts of evaporation characteristics of SiO2 on uniformity of thin film thickness,the heat distribution of e-beam spot is calculated and simulated,and the mass distribution is calculated.According to the mass distribution and the change of evaporation angle of point on evaporation surface,the thin film thickness distribution on spherical surface and flat surface is calculated.The reason of making the impact of evaporation characteristics of SiO2 on uniformity of thin film thickness,and the particularity of thin film thickness distribution are concluded,which offer references of adjusting and improving the technological parameters for thin film coating of SiO2 material.