真空蒸镀氟化镁增透膜的厚度与均匀性控制.pdf

真空蒸镀氟化镁增透膜的厚度与均匀性控制/溫才等
真空蒸镀氟化镁增透膜的厚度与均匀性控制
温才,令勇洲,李文俊,刘虹,寇采懿,蒋耀,唐金龙
(西南科技大学理学院,绵阳621010)
摘要基于光学增透膜与真空蒸发镀膜的基本原理,从MgF2原料状态、原料蒸镀质量、蒸发源与基片间距等
方面,研究了热电阻和电子東蒸镀的MgF2導膜厚度与其均匀性的控制工艺,以制备出高效的MgF2增透膜。结果
表明:对于颗粒度较小或熔点较低的原料,热电阻比电子東蒸镀更易控制,并可避免原料污染;原料实际蒸镀质量与
膜厚呈較好的线性关系;实际蒸镀质量相同的多晶颗粒与粉末状原料相比,前者蒸镀膜更厚;基片置于旋转工转盘中
心比其侧部区蒸镀膜更厚、均匀性更好。最后利用旋转球面夹具的小平面源蒸发模型很好地解释了上述实验结
果
关键词真空蒸镀MgF2增透膜厚度均匀性
中图分类号:TB34
文献标识码:A
Thickness and Uniformity Control of Vacuum Evaporated Magnesium
Fluoride Antireflection Coatings
WEN Cai, LING Yongzhou, LI Wenjun, LIU Hong, KOU Caiyi, JIANG Yao, TANG Jinlong
( School of Science, Southwest University of Science and Technology, Mianyang 621010)
Abstract For preparing high officiency Mgf2 antireflection coatings, the thickness and uniformity control of
the Mgf% film evaporated by thermal resistance and electron beam were studied. On the basis of principles of antire-
flection coatings and vacuum evaporation, many factors such as the weight and physical form of raw materials and th
distance between evaporation source and substrates were carefully studied. The results show that for the raw materials
in small particles or with low melting point, thermal resistance evaporation can not only control more easily but also
avoid the raw material pollution comparing with electron beam evaporation the actual weight of the evaporated raw
materials is approximately linear to the film thickness; although the actual weight is equal, the thickness of film evapo-
rated from the raw materials in polycrystalline particles form is higher than that in powder form; the thickness and uni
formity of the film are higher for the substrates in the center than those in the side of the rotating disk. At last, these
experimental results are well explained by the evaporation model of the small plane source for rotating spherical fix-
Key words vacuum evaporation, Mgf antireflection coatings, thickness, uniformity
项重要指标。薄膜厚度将直接影响不同波长入射光的增透
引言
效果,而薄膜厚度的均匀性将直接影响光学器件的稳定性
gF2增透膜具有折射率低(N=1.38)、光学损耗低、透和可靠性。
明波段宽、膜层机械强度大和激光损伤阈值髙等优异性能,
真空蒸发镀膜是在真空室中加热蒸发容器中的原料,使
因而被广泛应用于光学器件,尤其是紫外光学器件-り,其作其原子或分子从表面气化逸出,形成蒸气流,人射到固体(称
用是增加透射光的强度,使光学系统成像更清晰。以K9玻为衬底或基片)表面,凝结成薄膜的方法。它是真空镀膜
璃为例,其N=1.52,在空气中若未镀增透膜,其表面反射率技术中发展最早、应用最广的一种,特别是其中的热电阻蒸
为4.,25%,若镀上一层接近理想膜厚(d=/(4N),代表入镀迄今已有100多年的历史。近几十年来,由于电子束轰击
射光波长)的MgF2单层膜后,其表面总反射率将降至蒸发、高频感应蒸发以及激光蒸发等技术在蒸发镀膜技术中
%6.。。近年,随着增透膜应用范围的不断拓宽及薄膜的厂泛运用,使这一类技术更趋完善。因此,真空蒸发镀膜
制备方法和设备的改进,MgF2増透膜性能特別是薄膜的强在目前的镀膜技术中仍处于相当重要的地位3。
度和抗潮性能得到很大提高-。但影响MgF2增透膜性能
尽管真空蒸镀设备构造简单、造价便宜、使用可靠,但在
的因素很多,其中薄膜厚度和均匀性一直是衡量其性能的两前人研究中没能较精确地控蒸镀的薄膜厚度以达到增透
兴国家自然科学基金(11104226);西南科技大学博土研究基金(10x7102)
温才:男,1981年生,讲师,博士,从事光电子材料与器件研究E-mail:wencai(@swust,edu.cn