蝙蝠翼效应下矩形光栅特征参数计算方法  

Calculation Method for Characteristic Parameters of Rectangular Gratings Under Batwing Effect

作　　者：范筱昕 张佳乐 高志山[1] 马剑秋 李赫然 陈露 雷李华[3] 傅云霞[3] 徐志毅 朱丹[1] 郭珍艳 袁群[1] Fan Xiaoxin;Zhang Jiale;Gao Zhishan;Ma Jianqiu;Li Heran;Chen Lu;Lei Lihua;Fu Yunxia;Xu Zhiyi;Zhu Dan;Guo Zhenyan;Yuan Qun(School of Electronic and Optical Engineering,Nanjing University of Science&Technology,Nanjing 210094,Jiangsu,China;Jiangsu Institute of Metrology,Nanjing 210023,Jiangsu,China;Shanghai Institute of Measurement and Testing Technology,Shanghai 201203,China)

机构地区：[1]南京理工大学电子工程与光电技术学院,江苏南京210094 [2]江苏省计量科学研究院,江苏南京210023 [3]上海市计量测试技术研究院,上海201203

出　　处：《光学学报》2023年第22期80-88,共9页Acta Optica Sinica

基　　金：国家自然科学基金(62175107,62205148);国家重点研发计划(2022YFF0706302);上海市自然科学基金(21ZR1483100);上海市优秀学术/技术带头人计划(21XD1425000)。

摘　　要：白光显微干涉术是微结构三维形貌无损测量的有效手段,但当沟槽深度小于光源相干长度时易产生蝙蝠翼效应。ISO-25178系列规定了由三维形貌计算沟槽深度和线宽两项特征参数的方法。该计算法则首先需要确定阶跃边缘位置,然而蝙蝠翼位于阶跃边缘,造成形貌中的阶跃边缘位置定位困难。本文针对上述问题,摒弃了从三维形貌中提取阶跃边缘位置的传统方法,依据干涉图像中矩形光栅上下表面边缘位置采样点相干峰分布的差异性,提取相干包络峰值位置,并计算得到用于区分阶跃上下表面的掩膜。本文提出的方法从垂直扫描干涉图像出发,同步实现三维形貌复原和阶跃边缘位置定位,继而准确、高效地计算沟槽深度和线宽。本文以两种不同特征参数的矩形光栅作为检测对象,比对了测量结果与标称值之间的偏差,并对测量过程中的误差项进行了分析。实验结果证明,本文方法具有良好的重复性和鲁棒性。Objective White light interferometry,as an effective non-destructive method,is widely employed for measuring characteristic parameters of microstructures.Among these microstructures,the rectangular grating is a typical periodic step structure and has extensive utilization in precision machining due to its diverse materialization properties based on surface morphology characteristic parameters.However,when the groove depth of the grating is smaller than the coherence length of the adopted light source,the batwing effect occurs near or at the edge of the step in the sample under measurement.ISO series 25178 provides a standard morphology for calculating the characteristic parameters of groove depth and linewidth through three-dimensional surface morphology analysis,which necessitates determining the position of the step edge.The batwing effect poses challenges to precisely locating the step edge position and may result in a false representation of information near the edge of the step discontinuity.We propose a new algorithm for determining the characteristic parameters of rectangular gratings by utilizing the distribution difference of the coherence signals between the upper and lower surfaces,thus avoiding the traditional method of extracting step edge position from three-dimensional surface morphology.The introduced algorithm demonstrates excellent measurement accuracy,high repeatability,and exceptional robustness in calculating the desired characteristic parameters of rectangular gratings.Methods We propose an algorithm for precise positioning of the step edge in rectangular gratings based on the distribution difference of the coherence peak among different sampling points.The algorithm is designed to improve the detection efficiency of characteristic parameters by incorporating parallel processing techniques.Firstly,during vertical scanning,the coherence signals undergo modulation.Simultaneously,the contrast information is obtained by the gravity method to extract the center of gravity position of the modulati

关 键 词：显微干涉 矩形光栅 蝙蝠翼效应 特征参数 二值化 

分 类 号：TH741[机械工程—光学工程]