高精度激光共焦半导体晶圆厚度测量  

High-precision laser confocal measurement of semiconductor wafer thickness

作　　者：李兆宇 刘子豪 王瑶莹 邱丽荣[1] 杨帅 LI Zhaoyu;LIU Zihao;WANG Yaoying;QIU Lirong;YANG Shuai(MIIT Key Laboratory of Complex-field Intelligent Exploration,Beijing Institute of Technology,School of Optics and Photonics,Beijing Institute of Technology,Beijing 100081,China)

机构地区：[1]北京理工大学光电学院复杂环境智能感测技术工信部重点实验室,北京100081

出　　处：《光学精密工程》2024年第7期956-965,共10页Optics and Precision Engineering

基　　金：国家自然科学基金联合基金集成项目(No.U22A6006)。

摘　　要：针对半导体晶圆厚度的高精度非接触测量问题与需求,提出了基于激光共焦的高精度晶圆厚度测量方法。该方法利用高分辨音圈纳米位移台驱动激光共焦光探针轴向运动扫描,利用激光共焦轴向响应曲线的峰值点对应物镜聚焦焦点的特性,分别对被测晶圆上下表面进行高精度瞄准定位;通过光线追迹算法精确计算出晶圆表面每个采样点的物理坐标,实现了晶圆厚度的高精度非接触测量。基于该方法构建了激光共焦半导体晶圆厚度测量传感器,实验和分析表明,该传感器的轴向分辨力优于5 nm,轴向扫描范围可达5.7 mm,6种晶圆厚度测量重复性均优于100 nm,单次测量时长小于400 ms。将共焦定焦技术有效地应用于半导体测量领域,为晶圆厚度的高精度、无损在线测量提供了一种新技术。Addressing the need for precise non-contact measurement of semiconductor wafer thickness,this study introduces a method based on laser confocal technology that ensures remarkable accuracy.It utilizes a voice coil nanodisplacement platform for high-resolution actuation of a laser confocal optical probe,enabling precise axial scanning.This method relies on identifying the peak points on the confocal laser's axial response curve,which are indicative of the objective lens's focal point,to accurately align and position the wafer's upper and lower surfaces.By accurately calculating the physical coordinates of each sampling point on the wafer surface through ray tracing algorithms,this technique achieves high-precision non-contact measurement of wafer thickness.A specialized laser confocal sensor for semiconductor wafer thickness measurement was developed,showcasing an axial resolution of under 5 nm,an axial scanning range of up to 5.7 mm,and repeatability in thickness measurement of under 100 nm across six wafer types.The process takes less than 400 ms for a single wafer.This research successfully applies confocal focusing technology to semiconductor measurement,offering a novel solution for high-precision,non-destructive,online wafer thickness measurement.

关 键 词：激光共焦 厚度测量 半导体晶圆 光线追迹 高精度 无损测量 

分 类 号：TN307[电子电信—物理电子学] TH741[机械工程—光学工程]