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Proceedings Paper

Approximate method of mask flatness factor in focus deviation
Author(s): Shinroku Maejima; Seiichiro Shirai; Akira Imai; Shuji Nakao; Koji Tange; Akira Chiba; Kunihiro Hosono; Koichiro Narimatsu
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Paper Abstract

Recent integrated circuit (IC) manufacturing processes require smaller critical dimension (CD) in order to facilitate the development of exposure tools with a higher numerical aperture (NA) and shorter wavelength. Consequently, the depth of focus (DOF) has considerably decreased, and the DOF currently required for 45-nm node devices is approximately 150 nm. Hence, the contribution of mask flatness to the total DOF increases. Inoue et al. systematically and precisely investigated the influence of mask flatness by using a free-standing plate and chucked plate interferometer. In this study, we fabricated several back side chrome (BSC) masks for focus monitoring, determined the flatness of these masks by an exposure experiment, and compared the flatness with that directly determined by using a free-standing plate interferometer. Thus, we verified the possibility of predicting the mask flatness component on an image plane by using the mask flatness data obtained using the interferometer.

Paper Details

Date Published: 20 May 2006
PDF: 9 pages
Proc. SPIE 6283, Photomask and Next-Generation Lithography Mask Technology XIII, 62833A (20 May 2006);
Show Author Affiliations
Shinroku Maejima, Renesas Technology Corp. (Japan)
Seiichiro Shirai, Renesas Technology Corp. (Japan)
Akira Imai, Renesas Technology Corp. (Japan)
Shuji Nakao, Renesas Technology Corp. (Japan)
Koji Tange, Renesas Technology Corp. (Japan)
Akira Chiba, Renesas Technology Corp. (Japan)
Kunihiro Hosono, Renesas Technology Corp. (Japan)
Koichiro Narimatsu, Renesas Technology Corp. (Japan)

Published in SPIE Proceedings Vol. 6283:
Photomask and Next-Generation Lithography Mask Technology XIII
Morihisa Hoga, Editor(s)

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