Abstract
Double-Ronchi shearing interferometry is a promising technique for in situ wavefront aberration measurement of the projection lens in photolithography systems. In practice, the non-uniformity of illumination is an important issue affecting the interference field, which has not been systematically researched. In this work, the interference field errors caused by non-uniform illumination distributions are analyzed utilizing the theories of scalar diffraction. The theoretical analysis has been verified by simulation and fundamental experiments. Results show that the uniformity requirements for the abrupt annular, Gaussian, and uniform random illumination distribution (RD) are 0.9434, 0.8439, and 0.2751, respectively, with a shear ratio of 5% and a relative wavefront reconstruction error of 1%. The uniformity of the three distributions is reduced to 0.6513, 0.5864, and 0.1234, respectively, with the shear ratio shrunk to 3%. When the shear ratio is less than 1%, there is no specific requirement for illumination uniformity.
© 2022 Optica Publishing Group
Full Article | PDF ArticleMore Like This
Yang Liu, Feng Tang, Sikun Li, and Xiangzhao Wang
Appl. Opt. 62(14) 3623-3631 (2023)
Yang Liu, Feng Tang, Xiangzhao Wang, Changzhe Peng, and Peng Li
Appl. Opt. 61(6) 1464-1474 (2022)
Huiwen Liu, Runzhou Shi, Yicheng Zhu, Yuqi Shao, Yuejia Li, and Jian Bai
Opt. Express 32(8) 13672-13687 (2024)