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Proceedings Paper

Coma measurement by transmission image sensor with a PSM
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Paper Abstract

As feature size decreases, especially with the use of resolution enhancement technique such as off axis illumination and phase shifting mask, fast and accurate in-situ measurement of coma has become very important in improving the performance of modern lithographic tools. The measurement of coma can be achieved by the transmission image sensor, which is an aerial image measurement device. The coma can be determined by measuring the positions of the aerial image at multiple illumination settings. In the present paper, we improve the measurement accuracy of the above technique with an alternating phase shifting mask. Using the scalar diffraction theory, we analyze the effect of coma on the aerial image. To analyze the effect of the alternating phase shifting mask, we compare the pupil filling of the mark used in the above technique with that of the phase-shifted mark used in the new technique. We calculate the coma-induced image displacements of the marks at multiple partial coherence and NA settings, using the PROLITH simulation program. The simulation results show that the accuracy of coma measurement can increase approximately 20 percent using the alternating phase shifting mask.

Paper Details

Date Published: 27 January 2005
PDF: 9 pages
Proc. SPIE 5645, Advanced Microlithography Technologies, (27 January 2005); doi: 10.1117/12.573642
Show Author Affiliations
Fan Wang, Shanghai Institute of Optics and Fine Mechanics, CAS (China)
Xiangzhao Wang, Shanghai Institute of Optics and Fine Mechanics, CAS (China)
Mingying Ma, Shanghai Institute of Optics and Fine Mechanics, CAS (China)
Dongqing Zhang, Shanghai Institute of Optics and Fine Mechanics, CAS (China)
Weijie Shi, Shanghai Institute of Optics and Fine Mechanics, CAS (China)
Jianming Hu, Shanghai Institute of Optics and Fine Mechanics, CAS (China)


Published in SPIE Proceedings Vol. 5645:
Advanced Microlithography Technologies
Yangyuan Wang; Jun-en Yao; Christopher J. Progler, Editor(s)

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