5 September 2001 Application of multistep quartz etching method to strong PSMs
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Proceedings Volume 4409, Photomask and Next-Generation Lithography Mask Technology VIII; (2001); doi: 10.1117/12.438334
Event: Photomask and Next Generation Lithography Mask Technology VIII, 2001, Kanagawa, Japan
Before strong plastic shifting masks (PSMs) are used in production mode, several problems, such as (Delta) CD, X- phenomenon, and phase non-uniformity must be resolved. Among these problems, the phase non-uniformity on the mask plate is the main topic in our study. A quartz substrate is not embedded with any etching stopper layer, which leads to inherent etching depth non-uniformity across the mask plate. In this paper, we carry out simulation on the dependency of phase variation for tolerable margin. The simulation result shows that the phase should be controlled within +/- 2 degree(s) off a targeted phase. Through some experiments, it is confirmed that the etching non-uniformity results from etching species' reaction with resist. Employment of a multi-step dry etching gives rise to remarkable improvement of the phase uniformity compared with a single-step etching.
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Hyoungdo Kim, Yong-Hoon Kim, Seong-Woon Choi, Woo-Sung Han, Jung-Min Sohn, "Application of multistep quartz etching method to strong PSMs", Proc. SPIE 4409, Photomask and Next-Generation Lithography Mask Technology VIII, (5 September 2001); doi: 10.1117/12.438334; https://doi.org/10.1117/12.438334



Dry etching


Wet etching

Phase shifting


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