基于光学三角法的芯片凸点高度测量  

A Bump Height Measurement Method Based on Optical Triangulation

作　　者：王棚 孟繁昌 张滋黎(指导) 王德钊 王珊 姚恩涛[1] 王磊[4] 叶瑞乾 WANG Peng;MENG Fanchang;ZHANG Zili;WANG Dezhao;WANG Shan;YAO Entao;WANG Lei;YE Ruiqian(College of Automation Engineering,Nanjing University of Aeronautics and Astronautics,Nanjing 211100,China;Institute of Microelectronics of the Chinese Academy of Sciences,Beijing 100029,China;Changchun University of Science and Technology,Changchun 130022,China;Xiamen University,Xiamen,Fujian 361101,China)

机构地区：[1]南京航空航天大学自动化学院,南京211100 [2]中国科学院微电子研究所,北京100029 [3]长春理工大学,长春130022 [4]厦门大学,福建厦门361101

出　　处：《光子学报》2022年第5期332-340,共9页Acta Photonica Sinica

基　　金：国家重点研发计划(No.2019YFB2006700)。

摘　　要：本文提出一种基于光学三角法的凸点高度快速高精度测量方法,基于斜入射光学三角法的基本原理,将一束LED线光束投射到凸点上,由相机采集芯片上光束反射的图像,根据图像形貌特征计算凸点的高度。该方法在传统三角测量法的基础上结合凸点的形貌信息,可利用凸点在相机上的投影特征精确计算出凸点顶部距离基底面的高度。在进行系统参数标定时,为解决传统三角法中投影和成像装置角度标定困难的问题,采用了一种新的标定方法,利用成像系统的放大率和像素高度比代替装置角度,实现了角度参数的间接标定,标定方法快速精确。利用该测量方法对芯片凸点高度进行测量,高度测量的标准偏差为0.58μm,重复多次测量同一个芯片凸点,其展伸不确定度小于±1μm,实验结果表明了该方法的准确性。2D/3D integrated circuit packaging technology is adopted in the process of wafer packaging and this technology uses wafer bumps to connect active devices.Inconsistent bump heights will cause circuit break after packaging,which will cause the whole chip to fail.Therefore,on-line detection of the height consistency of bumps is required during wafer packaging.To meet the above requirements,a fast and highprecision bump height measurement method based on optical triangulation method is studied.Based on the basic principle of oblique incidence optical triangulation method,the line beam is projected onto the chip bump,and the reflected beam on the chip surface is collected by the camera after through the imaging system.The height of the bump is calculated according to the geometric characteristics of the light stripe in the image collected by the camera and the distance between the spot on the top of the bump and the light stripe.Compared with spectral confocal method and white light interferometry,this method has the advantages of high speed and high measurement efficiency,and can meet the needs of on-line measurement of chip packaging defects.When calibrating the parameters of the chip bump height measurement system,in order to solve the difficult problem of angle calibration of projection and imaging device in the traditional triangulation method,a new calibration method is adopted:the magnification and pixel height ratio of the imaging system are used to replace the device angle to realize the indirect calibration of angle parameters.In order to accurately calibrate the pixel height ratio,a laser interferometer is used to accurately measure the height deviation of the reference plane.The center coordinate of the light strip on the reference plane is extracted by the gray centroid method to obtain the center offset of the light strip.The pixel height ratio is calculated according to the center offset of the light strip and the height deviation of the reference plane.A high-precision circular calibration plate is use

关 键 词：光学三角法 显微测量 凸点高度测量 参数标定 不确定度分析 

分 类 号：TH741[机械工程—光学工程]