22 January 2001 Effect of mask reduction ratio in alternating phase-shift masks
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In this paper we analyze the effect of mask reduction ratio in alternating phase shift masks. To properly predict image imbalance for different reduction ratios, a topography simulator was used. As the mask reduction ratio is increased, the aerial image imbalance is improved. As the reduction ratio is decreased, the amount of undercutting to compensate for the difference of image imbalance is increased. For undercut margins with lOOnm line/space patterns, 4X reduction has about ± 200 A of undercut margins, while 6X and 10X have about ± 300 A. The phase margin for 120 nm line/space patterns is about ± 1.5° regardless of reduction ratios. As the mask reduction ratio is varied, the optimum phase is shifted to keep the aerial image displacement constant through focus.
© (2001) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
In-Gyun Shin, In-Gyun Shin, Sung-Ho Lee, Sung-Ho Lee, Yong-Hoon Kim, Yong-Hoon Kim, Seong-Woon Choi, Seong-Woon Choi, Woo-Sung Han, Woo-Sung Han, Jung-Min Sohn, Jung-Min Sohn, Tong-Kun Lim, Tong-Kun Lim, } "Effect of mask reduction ratio in alternating phase-shift masks", Proc. SPIE 4186, 20th Annual BACUS Symposium on Photomask Technology, (22 January 2001); doi: 10.1117/12.410707; https://doi.org/10.1117/12.410707

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