29 June 2012 Black border with etched multilayer on EUV mask
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Proceedings Volume 8441, Photomask and Next-Generation Lithography Mask Technology XIX; 84411K (2012) https://doi.org/10.1117/12.965536
Event: Photomask and NGL Mask Technology XIX, 2012, Yokohama, Japan
EUV lithography is the most promising candidate for semiconductor device manufacturing of 1x nm half pitch and beyond. For the practical use, EUV mask with a thin absorber could be adopted because of less shadowing effect. EUV reflectivity from the thin absorber is about 1~3%. It would cause CD change on wafer especially at the exposure field edge due to the leakage of the EUV light from neighboring exposure shots.1 To avoid this phenomenon, light shield black border is needed at the edge of pattern area on mask. Stacked absorber type and ML-etched type of light shield black border have been proposed in the past.2 The most important things for these black borders are that there is no reflection of EUV light and no defect which affects pattern CD on wafer. ML-etched black border is considered to be applied for early practical use from a viewpoint of manufacturability. Because CD degradation and defect increase might happen due to 2nd litho and etch process on its main pattern area in manufacturing process of stacked absorber type. In this paper, we will show several evaluation results regarding ML-etched black border we have developed. It has a good light shield performance for EUV and low DUV light reflection. Defect inspection in black border area can be performed successfully by three kinds of inspection tools. As a result, most of the defects seemed not to be printable to wafer. We also evaluated CD change, flatness change linked to mask IP shift and particle contamination on main pattern area. What it comes down to is that there is no show-stopper for ML-etched BB process for now.
© (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Norihito Fukugami, Kazuaki Matsui, Genta Watanabe, Takeshi Isogawa, Shinpei Kondo, Yutaka Kodera, Yo Sakata, Shinji Akima, Jun Kotani, Hiroaki Morimoto, and Tsuyoshi Tanaka "Black border with etched multilayer on EUV mask", Proc. SPIE 8441, Photomask and Next-Generation Lithography Mask Technology XIX, 84411K (29 June 2012); doi: 10.1117/12.965536; https://doi.org/10.1117/12.965536


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