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Proceedings Paper

Alternative EUV mask technology to compensate for mask 3D effects
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Paper Abstract

Traditional EUV masks, with absorber on top of the multi-layer (ML) mirror, generally suffer from mask 3D effects: H/V shadowing, best focus shifts through pitch and pattern shifts through focus. These effects reduce the overlapping process window, complicate optical proximity correction and generate overlay errors. With further pitch scaling, these mask 3D effects are expected to become stronger, increasing the need for a compensation strategy. In this study, we have proven by simulations and experiments that alternative mask technologies can lower mask 3D effects and therefore have the potential to improve the imaging of critical EUV layers. We have performed an experimental imaging study of a prototype Etched ML mask, which has recently become available. This prototype alternative mask has only half the ML mirror thickness (20 Mo/Si pairs) and contains no absorber material at all. Instead, the ML mirror is etched away to the substrate at the location of the dark features. For this Etched ML mask, we have compared the imaging performance for mask 3D related effects to that of a standard EUV mask, using wafer exposures at 0.33 NA. Experimental data are compared to the simulated predictions and the benefits and drawbacks of such an alternative mask are shown. Besides the imaging performance, we will also discuss the manufacturability challenges related to the etched ML mask technology.

Paper Details

Date Published: 9 July 2015
PDF: 11 pages
Proc. SPIE 9658, Photomask Japan 2015: Photomask and Next-Generation Lithography Mask Technology XXII, 96580I (9 July 2015); doi: 10.1117/12.2197213
Show Author Affiliations
Lieve Van Look, IMEC (Belgium)
Vicky Philipsen, IMEC (Belgium)
Eric Hendrickx, IMEC (Belgium)
Geert Vandenberghe, IMEC (Belgium)
Natalia Davydova, ASML Netherlands B.V. (Netherlands)
Friso Wittebrood, ASML Netherlands B.V. (Netherlands)
Robert de Kruif, ASML Netherlands B.V. (Netherlands)
Anton van Oosten, ASML Netherlands B.V. (Netherlands)
Junji Miyazaki, ASML Netherlands B.V. (Netherlands)
Timon Fliervoet, ASML Netherlands B.V. (Netherlands)
Jan van Schoot, ASML Netherlands B.V. (Netherlands)
Jens Timo Neumann, Carl Zeiss SMT GmbH (Germany)

Published in SPIE Proceedings Vol. 9658:
Photomask Japan 2015: Photomask and Next-Generation Lithography Mask Technology XXII
Nobuyuki Yoshioka, Editor(s)

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