Abstract
As a critical dimension shrinks, the degradation in image quality caused by wavefront aberrations of projection optics in lithographic tools becomes a serious problem. It is necessary to establish a technique for a fast and accurate in situ aberration measurement. We introduce what we believe to be a novel technique for characterizing the aberrations of projection optics by using an alternating phase-shifting mask. The even aberrations, such as spherical aberration and astigmatism, and the odd aberrations, such as coma, are extracted from focus shifts and image displacements of the phase-shifted pattern, respectively. The focus shifts and the image displacements are measured by a transmission image sensor. The simulation results show that, compared with the accuracy of the previous straightforward measurement technique, the accuracy of the coma measurement increases by more than and the accuracy of the spherical-aberration measurement increases by approximately .
© 2006 Optical Society of America
Full Article | PDF ArticleMore Like This
Zicheng Qiu, Xiangzhao Wang, Qunyu Bi, Qiongyan Yuan, Bo Peng, and Lifeng Duan
Appl. Opt. 48(19) 3654-3663 (2009)
Bo Peng, Xiangzhao Wang, Zicheng Qiu, Yuting Cao, and Lifeng Duan
Appl. Opt. 49(15) 2753-2760 (2010)
Mingying Ma, Xiangzhao Wang, and Fan Wang
Appl. Opt. 45(32) 8200-8208 (2006)