晶圆定位标记光学成像的自适应聚焦评价  

Adaptive focusing evaluation algorithm for optical imaging of wafer positioning marks

作　　者：杨金 张航瑛 孟凯[1,2,3] 楼佩煌 YANG Jin;ZHANG Hangying;MENG Kai;LOU Peihuang(College of Mechanical and Electrical Engineering,Nanjing University of Aeronautics and Astronautics,Nanjing 210016,China;National Key Laboratory of Microwave Photonics,Nanjing 210016,China;Key Laboratory of Aerospace Integrated Circuits and Microsystem,Ministry of Industry and Information Technology,Nanjing 210016,China)

机构地区：[1]南京航空航天大学机电学院,江苏南京210016 [2]微波光子技术国家级重点实验室,江苏南京210016 [3]工业和信息化部空天集成电路与微系统重点实验室,江苏南京210016

出　　处：《光学精密工程》2025年第3期389-401,共13页Optics and Precision Engineering

基　　金：国家自然科学基金资助项目(No.62205175);江苏省科技成果转化专项资金揭榜挂帅项目(No.BA2021005);江苏省重点研发计划揭榜挂帅项目课题(No.BE2023015-2);南京航空航天大学引进人才科研启动项目(No.YAH22047,No.YAH23025)。

摘　　要：晶圆定位标记尺寸小,形貌多,传统聚焦评价函数进行计算时存在稳定性差、灵敏度低等问题。针对上述问题提出了一种基于多向梯度方差的自适应聚焦评价算法。首先针对标记图像进行特征边缘像素点自适应采样提取;然后联立Brenner函数和Roberts函数,构建适用于晶圆定位标记的多向梯度评价函数,对采样的像素点进行评价计算,得到初始聚焦评价函数值;最后对图像集的初始聚焦评价函数值进行方差计算,优化函数抗噪性,得到最终的聚焦评价函数值。实验结果表明,本文所提算法相较于传统评价算法平缓区域波动量降低了61.49%,灵敏度提升了2.56倍。本算法的提出为实现晶圆定位标记乃至其他具备明显边缘特征结构的微纳标记图像实现高灵敏度自动聚焦提供了一种更优的计算策略。The wafer positioning mark is characterized by its small size and diverse shapes.Traditional fo⁃cus evaluation functions exhibit limitations,including poor stability and low sensitivity during computa⁃tion.To address these challenges,an adaptive focus evaluation algorithm based on multi-directional gradi⁃ent variance was proposed in this paper.Initially,feature edge pixel points of the mark image were adap⁃tively sampled and extracted.Subsequently,a multi-directional gradient function,tailored for wafer posi⁃tioning marks,was developed by integrating the Brenner function and the Roberts function.The sampled pixel points were then evaluated to derive the initial focus evaluation function value.Finally,the variance of the initial focus evaluation function values across the image set was computed,thereby enhancing the ro⁃bustness of the function against noise and yielding the final focus evaluation function value.Experimental results indicate that the proposed algorithm reduces fluctuations in flat areas by 61.49%and enhances sen⁃sitivity by a factor of 2.56 compared to traditional evaluation algorithms.This innovative approach pro⁃vides a superior calculation strategy for achieving high-sensitivity automatic focusing of wafer positioning marks and other micro-nano mark images characterized by distinct edge feature structures.

关 键 词：成像系统 图像质量评价 边缘分析 自动聚焦 聚焦函数 

分 类 号：TH744[机械工程—光学工程] TP391.4[机械工程—仪器科学与技术]