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摘要:
膜厚均匀性作为高精度光学薄膜的重要参数,对光学薄膜的性能起到至关重要的作用,特别是大尺寸高精度反射膜,对膜厚均匀性的要求极高。本文通过研究蒸发源的发射特性与膜厚分布,结合Mathcad软件建立精准数学及物理模型,编写自动程序,模拟修正挡板形状,极大地提高了薄膜制备均匀性修正的效率与准确性。通过该方法,在公自转行星蒸发沉积设备上制备了直径为320 mm的非球面深紫外反射镜,在紫外(240~300 nm)波段平均反射率大于97.5%,均匀性优于0.5%。本研究对大口径非球面薄膜的均匀性修正提供了理论基础与技术支撑。
Abstract:As an important parameter of high-precision optical films, thickness uniformity plays a vital role in their performance. Large-size high-precision reflective films have especially high requirements for thickness uniformity. In this paper, the efficiency and accuracy of the uniformity correction of thin films are greatly improved by studying the emission characteristics and film thickness distribution of the evaporation source, combining Mathcad software to establish precise mathematical and physical models, writing automatic programs, and simulating the correcting mask shape. Through this method, an aspherical deep ultraviolet reflector with a diameter of 320 mm is prepared on public autobiographical planetary evaporation deposition equipment. The average reflectance at 240−300 nm ultraviolet waveband is greater than 97.5%, and the uniformity is better than 0.5%. This research provides a theoretical basis and technical support for the uniformity correction of large aperture aspheric films.
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Key words:
- thin film/
- uniformity/
- mask/
- large aperture/
- aspheric
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表 1公自转行星结构运动轨迹
Table 1.The orbit of revolution of a planetary structure
Geometry Trajectory Coordinates of any point on the substrate holder ${x_{{p} } } = D\sin\; {\omega _1}t + \rho \sin \;({\omega _1}t + {\omega _2}t)$
${y_{{p} } } = D\cos \;{\omega _1}t + \rho \cos\; \left( { {\omega _1}t + {\omega _2}t} \right)$
${\textit{z}_p} = H$Evaporation distance $\sqrt { { {\left( { {x_{ {p} } } } \right)}^2} + { {\left( { {y_{ {p} } } - L} \right)}^2} + { {\left( { {\textit{z}_{ {p} } } } \right)}^2} }$ Evaporation angle $\mathrm{cos}\;\varphi=\dfrac{\boldsymbol{D}\cdot\boldsymbol{PP_{{\rm{s}}} } }{\left|\boldsymbol{D}\right|\left|\boldsymbol{PP_{{\rm{s}}} }\right|}$ Projected angle $\mathrm{cos}\;\theta =\dfrac{\boldsymbol{D}\cdot\boldsymbol{PP_{ {\rm{s} } } } }{\left|\boldsymbol{D}\right|\left|\boldsymbol{PP_{ {\rm{s} } } }\right|}$ 表 2大尺寸非球面反射镜技术参数
Table 2.The technical parameters of the large aspherical mirror
Parameters Indicators Substrate JGS1 Angle of incidence /(°) 0 Spectral range /nm 230~300 Reflectance ≥97.5% Heterogeneity ≤0.5% 表 3薄膜制备工艺参数
Table 3.The process parameters of thin film preparation
Material Ion source voltage
/VIon
source current
/mAIon source O2gas flow
/ml·min−1O2gas flow
/ml·min−1Substrate temperature/°C Deposition rate
/nm·s−1HfO2 500 400 50 50 200 0.12 SiO2 500 400 50 0 200 0.8 -
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