11 May 2007 Mask quality assurance in cleaning for haze elimination using flexible mask specifications
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Proceedings Volume 6607, Photomask and Next-Generation Lithography Mask Technology XIV; 660708 (2007) https://doi.org/10.1117/12.728921
Event: Photomask and Next-Generation Lithography Mask Technology XIV, 2007, Yokohama, Japan
Abstract
We propose a new method of quality assurance for attenuated phase shifting mask (PSM) using the concept of the flexible mask specifications to extend the life of PSM [1]. The haze on PSM is a major issue for ArF lithography in semiconductor device manufacturing since it causes decline of device yield. PSM irradiated by ArF laser is periodically cleaned before haze is printed on wafer, which is a killer defect. Repetition of cleaning causes great changes of properties, i.e. phase, transmittance. Therefore, the number of times cleaning is performed has been limited by predetermined specifications based on ITRS. In this paper, relaxation of the pass/ fail criteria are studied as one solution to this limitation problem. In order to decide a suitable number of times for cleaning to be performed, we introduce the concept of flexible mask specifications, taking lithography margin into account. Firstly, we obtained mask parameters before cleaning; these parameters were, for instance, phase, transmittance and CD. Secondly, using these parameters, we simulated images of resist pattern exposed on wafer and obtained exposure latitude at desired depth of focus. Thirdly, we simulated mask parameters and exposure latitude when the mask was cleaned several times and obtained correlation between number of times cleaning is performed and exposure latitude. And finally, we estimated suitable pass/ fail criteria of mask parameters and the maximum number of times cleaning should be performed for each mask at the standard exposure latitude. In the above procedure, the maximum number of times cleaning should be performed exceeded that determined in the case of conventional specifications based on ITRS.
© (2007) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Kyo Otsubo, Shinji Yamaguchi, Yukiyasu Arisawa, Hidefumi Mukai, Toshiya Kotani, Hiromitsu Mashita, Hiromitsu Hashimoto, Takashi Kamo, Tomohiro Tsutsui, Osamu Ikenaga, "Mask quality assurance in cleaning for haze elimination using flexible mask specifications", Proc. SPIE 6607, Photomask and Next-Generation Lithography Mask Technology XIV, 660708 (11 May 2007); doi: 10.1117/12.728921; https://doi.org/10.1117/12.728921
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