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Proceedings Paper

Performance data of a variable transmission phase shifting mask blank for 193nm lithography enhanced by inspection contrast tuning
Author(s): Hans Becker; Markus Renno; Ulrich Hermanns; Holger Seitz; Ute Buttgereit; Konrad Knapp; Günter Hess
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Paper Abstract

Schott's already commercially available two layer Ta/SiO2 phase shift system can be tuned from 6% up to 40% transmission for 157, 193 and 248 nm lithography wavelengths. Thus one film patterning process provides a wide product range. Attenuated phase shift masks for 6%, 20% and 30% transmission at 193nm were produced. Tests for laser stability and chemical durability show excellent performance. The phase shifting film achieves a high etch selectivity to the substrate. Dry etch process development is done at IMS chips in Stuttgart, Germany, to provide our customers the service of a good start process for patterning. Results of phase and transmission uniformity are included. Our newest development enhances the layer system and provides a better contrast for inspection in reflection mode. Transmission of our standard two layer Ta/SiO2 PSM system is below the required 20% at inspection wavelengths. The reflectivity of 30% to 40% can be lowered by insertion of an additional contrast layer. The thickness of this contrast layer is adjusted to achieve the required reflection at inspection wavelengths, while the other film thicknesses are tuned to preserve the desired transmission and 180° phase shift at the design wavelength. As first examples 6% and 20% transmission PSM for 193 nm were tested. Reflection at 257 nm and 365 nm inspection wavelengths can be lowered from initial 30% to 40% down to about 10%.

Paper Details

Date Published: 4 October 2005
PDF: 10 pages
Proc. SPIE 5963, Advances in Optical Thin Films II, 59630J (4 October 2005); doi: 10.1117/12.625210
Show Author Affiliations
Hans Becker, SCHOTT Lithotec AG (Germany)
Markus Renno, SCHOTT Lithotec AG (Germany)
Ulrich Hermanns, SCHOTT Lithotec AG (Germany)
Holger Seitz, SCHOTT Lithotec AG (Germany)
Ute Buttgereit, SCHOTT Lithotec AG (Germany)
Konrad Knapp, SCHOTT Lithotec AG (Germany)
Günter Hess, SCHOTT Lithotec AG (Germany)

Published in SPIE Proceedings Vol. 5963:
Advances in Optical Thin Films II
Claude Amra; Norbert Kaiser; H. Angus Macleod, Editor(s)

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