We propose an in situ technique for measuring an even aberration of lithographic projection optics. By using the Hopkins theory of partially coherent imaging and the thick-mask model, the linear relationship between the intensity difference of adjacent peaks in an alternating phase-shifting mask image and an even aberration is established by equations and verified by numerical results. The sensitivity of measuring the even aberration of lithographic projection optics based on this linear relationship is analyzed, and the measurement mark is designed accordingly. Measurement performance of the present technique is evaluated using the lithographic simulator PROLITH, which shows that the present technique is capable of measuring the even aberration of lithographic projection optics with ultrahigh measurement accuracy.
© 2010 Optical Society of America
Diffraction and Gratings
Original Manuscript: March 15, 2010
Revised Manuscript: April 19, 2010
Manuscript Accepted: April 20, 2010
Published: May 12, 2010
Bo Peng, Xiangzhao Wang, Zicheng Qiu, Yuting Cao, and Lifeng Duan, "Even aberration measurement of lithographic projection optics based on intensity difference of adjacent peaks in alternating phase-shifting mask image," Appl. Opt. 49, 2753-2760 (2010)