Abstract

Double-Ronchi shearing interferometry is a promising wavefront aberration measurement system for advanced lithography projection lens systems. The image grating defocusing is a key systematic error of the interferometer. However, the effects and elimination of this error have not been systematically researched. In this work, the interference field effects caused by the image grating defocusing are analyzed based on the theories of scalar diffraction, and a method to eliminate the effects is proposed. The theoretical analysis has been verified by a simulation and experiments. The results show that the error of image grating defocusing is mainly expressed as the Zernike ${{\rm Z}_4}$ term and ${{\rm Z}_9}$ term in the reconstructed wavefront, and the coefficients of ${{\rm Z}_4}$, and ${{\rm Z}_9}$, respectively, are related to ${{\rm NA}^2}$, ${{\rm NA}^4}$, and the defocus distance $z$. When the numerical aperture (NA) of the under-test projection lens is 0.6, 99.8384% of the errors caused by the image grating defocusing can be removed. When the NA is reduced to 0.3, 99.9854% of the errors can be removed. Additionally, when the NA is less than 0.1, almost all the errors can be eliminated.

© 2023 Optica Publishing Group

Effects of illumination non-uniformity on the double-Ronchi lateral shearing interference field

Yang Liu, Feng Tang, Sikun Li, Xiangzhao Wang, and Rong Su
Appl. Opt. 61(34) 10299-10308 (2022)

Rigorous simulation model of double-Ronchi shearing interferometry on lithographic tools

Zhiyuan Niu, Sikun Li, and Yang Liu
Appl. Opt. 62(18) 4759-4765 (2023)

Wavefront measurements using the Ronchi test for high-NA lithography projection lenses

Xinfeng Yu and Jiaqi Li
Appl. Opt. 62(19) 5057-5063 (2023)

Lateral shearing interferometry method based on double-checkerboard grating by suppressing aliasing effect

Huiwen Liu, Runzhou Shi, Yicheng Zhu, Yuqi Shao, Yuejia Li, and Jian Bai
Opt. Express 32(8) 13672-13687 (2024)

Applicability of the Van Cittert–Zernike theorem in a Ronchi shearing interferometer

Yang Liu, Feng Tang, Xiangzhao Wang, Changzhe Peng, and Peng Li
Appl. Opt. 61(6) 1464-1474 (2022)