Lisong DONG, Yanqiu LI^*, Xuejia GUO, Hao LIU, and Ke LIU

Key Laboratory of Photoelectron Imaging Technology and System of Ministry of Education of the P. R. China, School of Optoelectronics, Beijing Institute of Technology, Beijing 100081, P. R. China

(Received September 13, 2013; Accepted March 11, 2014)

Current aerial image based aberration measurement methods are all derived from the scalar imaging theory which is not applicable to hyper-NA lithography. Here we propose an aberration measurement method for the lithography system with an arbitrary NA based on the rigorous vector imaging theory. The retrieval error of the proposed method is clearly demonstrated by comparing with the method based on the scalar imaging theory for an immersion NA 1.35 projector using numerical results. The results show that the maximal retrieval error of our method is below 0.5mλ, while that of previous method is above 4mλ. In addition, the effect of practical aerial image metrology accuracy on the retrieval accuracy of proposed technique is analyzed. The results obtained demonstrate that the retrieval accuracy of our method is greatly improved, and the proposed technique is applicable to the retrieval of the wavefront aberration of a projector with hyper-NA.

Key words: lithography, hyper-NA, aerial image, aberration measurement, vector imaging theory

^*E-mail address: liyanqiu@bit.edu.cn