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| Research of Auto-focus System on Metrological Ultraviolet Microscope |
| YIN Chuan-xiang1,GAO Si-tian2,LI Qi2,LI Wei2,SHI Yu-shu2,LI Shi2 |
1. Hefei University of Technology, Hefei, Anhui 230009, China;
2. National Institute of Metrology, Beijing 100029, China |
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Abstract The metrological ultraviolet microscope is a traceable optical device.It uses 248 nm deep ultraviolet illumination light and a 100 × UV objective lens to up to 100 nm optical resolution.Because of the high resolution,it will be easily occur defocus phenomenon.In order to enhance the measurement accuracy, it is required the real-time auto-focus function when measuring lithography photomask.As a part of metrological UV microscope, the auto-focus system utilizes UV camera, UV lens, and lens actuator to obtain a series of optical slice images,then several key areas are set as the focus window,next the image sharpness evaluation function based on coif wavelet transform is used to find the best focus position.Finally, the mixed technology of VC and Matlab is used to achieve auto-focus for the optical measurement.After experimental verification, it is proved that the focusing accuracy of the system can achieve 0.5μm.
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［1］高思田.计量型原子力显微镜的研究［D］.天津:天津大学,2007.
［2］卢明臻,高思田,金其海,等.一种用于纳米计量的原子力显微镜测头的设计［J］.中国计量学院学报.2006,17(3):178-181.
［3］柳忠尧,闫聚群,张蕊,等.用于线宽测量的偏振干涉共焦显微镜测量方法［J］.计量学报,2005,26(2):115-119.
［4］Bodermann B, Buhr E, Ehret G, et al.Optical metrology of micro-and nanostructures at PTB: status and future developments［C］//Ninth International Symposium on Laser Metrology.International Society for Optics and Photonics,Singapore,2008.
［5］Attota R, Silver R.Nanometrology using a through-focus scanning optical microscopy method［J］.Measurement Science and Technology, 2011, 22(2): 024002.
［6］徐毅,高思田,李晶.纳米、亚微米标准样板及SPM量值溯源［J］.计量学报,2003,24(2):81-84.
［7］毛邦福.显微镜自动对焦系统的设计与优化［D］.浙江:浙江大学,2006.
［8］金小亮.纺织专用显微自动对焦技术研究［D］.西安:西安工程大学,2011.
［9］ Li Q, Gao S T, Li W, et al.Critical Dimensional Linewidth Calibration using UV Microscope and Laser Interferometry［C］//The 9th International Symposium on Precision Engineering Measurements and Instrumentation,Guiyang, China,2013.
［10］张明凯,高思田,卢荣胜,等.紫外扫描线宽测量系统的研究［C］//国际前沿光学成像技术与应用学术研讨,苏州,2013.
［11］李文煜.VC与Matlab混合编程实现图像处理［J］.计算机仿真,2005,22(1):254-257.
［12］朱新亚,田爱玲.Matlab与VC接口在图像及数据处理中的应用［J］.国外电子测量技术,2006,25(11),44-47. |
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2014, Vol. 35 
