Extreme-ultraviolet (EUV) lithography remains a leading contender for use in the mass production of nanoelectronics at the node. Great progress has been made in all areas of EUV lithography, including the crucial issue of fabrication of diffraction-limited optics. To gain an accurate understanding of the projection optic wavefront error in a completed lithography tool requires lithography-based aberration measurements; however, making such measurements in EUV systems can be challenging. We describe the quantitative lithographic measurement of spherical aberration in a 0.3 numerical aperture. EUV microfield optic. The measurement method is based on use of the unique properties of a programmable coherence illuminator. The results show the optic to have rms spherical error, whereas interferometric measurements performed during the alignment of the optic indicated a spherical error of less than .
© 2006 Optical Society of AmericaFull Article | PDF Article
Jinwon Sung, Mahesh Pitchumani, and Eric G. Johnson
Appl. Opt. 42(11) 1987-1995 (2003)
Fan Wang, Xiangzhao Wang, Mingying Ma, Dongqing Zhang, Weijie Shi, and Jianming Hu
Appl. Opt. 45(2) 281-287 (2006)
Fan Wang, Xiangzhao Wang, and Mingying Ma
Appl. Opt. 45(24) 6086-6093 (2006)