基于镜像焦面检测对准标记的套刻性能原位测量技术

套刻性能是现代高精度步进扫描投影光刻机的重要性能指标之一。提出了一种基于镜像焦面检测对准标记(简称“镜像焦面检测对准标记”)的光刻机套刻性能原位测量技术。该技术通过对曝光在硅片上的镜像焦面检测对准标记图形进行光学对准,利用标记图形对准位置与理想位置偏差实现套刻性能的原位检测。实验结果表明该技术在进行套刻误差的精确测量的同时还可以全面、定量地计算影响光刻机单机套刻误差的场内参量及场间参量。与目前套刻性能原位测量技术相比,该技术有效地避免了测量精度对轴向像质限制的依赖,简化了光刻机整机性能检测的过程。

An In-Situ Method for Measuring the Overlay Performance of a Lithographic System with Mirror-Symmetry FOCAL Marks

Overlay is one of key performances for modern lithographic projection systems with high-precision, a novel method for in-situ measuring the overlay performance of a lithographic system with the marks is presented. In the method, many mirror-symmetry focus calibration using alignment procedures (FOCAL) marks are printed on a wafer. The printed images of these marks are aligned by an optical alignment system and the alignment positions of the images are recorded. From the positions, overlay performance can be obtained. Through the experiments, it is demonstrated that the overlay errors, intrafield parameters and interfield parameters can be obtained with high accuracy. Compared to the XY-SETUP technique, the method avoids the dependency of measurement accuracy on the corrections of axial aberrations and makes it much simpler to perform a full-scale evaluation of a lithographic system.