20 May 2006 Approximate method of mask flatness factor in focus deviation
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Proceedings Volume 6283, Photomask and Next-Generation Lithography Mask Technology XIII; 62833A (2006) https://doi.org/10.1117/12.681829
Event: Photomask and Next Generation Lithography Mask Technology XIII, 2006, Yokohama, Japan
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.
© (2006) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Shinroku Maejima, Shinroku Maejima, Seiichiro Shirai, Seiichiro Shirai, Akira Imai, Akira Imai, Shuji Nakao, Shuji Nakao, Koji Tange, Koji Tange, Akira Chiba, Akira Chiba, Kunihiro Hosono, Kunihiro Hosono, Koichiro Narimatsu, Koichiro Narimatsu, "Approximate method of mask flatness factor in focus deviation", Proc. SPIE 6283, Photomask and Next-Generation Lithography Mask Technology XIII, 62833A (20 May 2006); doi: 10.1117/12.681829; https://doi.org/10.1117/12.681829

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