Ultraviolet scanning linewidth measuring system
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摘要: 设计了一套紫外光学线宽测量系统用于微纳线宽、栅格的测量。在原有深紫外显微镜的基础上,设计了新的探测光路,在成像面设置针孔接收来自样品的光信号,用样品扫描方式来得到样品轮廓。该装置使用紫外光学检测设备减小对象的衍射尺寸,提高检测分辨率,使用激光干涉仪对被测线宽进行溯源。用白光CCD图像实现自动聚焦,确定待测线宽样板平面位置。采用压电陶瓷纳米台在轴向采取序列图像,用聚焦评价函数来判定聚焦清晰度。通过对多种自动聚焦算法性能的比较,采用小波分解自动聚焦算法。确定了紫外成像系统的小波基、分解层数、小波消失矩等参数。Abstract: An ultraviolet imaging system was designed for quantitative characterization of micro-and nanostructures. A beam splitter inserted in the detection path reflected the signal from sample to a pinhole on the imaging plane. The sample was scanned to obtain the sample profile. The DUV light from apparatus was utilized to reduce the diffraction limit size and enhance resolution; and laser interferometer was used to trace the line width to international SI unit. CCD image was used to auto-focus the sample. Sequence images were captured along axial direction and the focus sharpness was determined by focus evaluation function. Algorithms were compared and wavelet algorithm for critical dimension auto-focused in used the ultraviolet measurement system. For wavelet, decomposition level, wavelet vanishing moments and other parameters for UV imaging system was determined.
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Key words:
- ultraviolet optical microscope /
- auto-focus /
- wavelet
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