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Proceedings Paper

EUV High-NA scanner and mask optimization for sub 8 nm resolution
Author(s): Jan van Schoot; Koen van Ingen Schenau; Gerardo Bottiglieri; Kars Troost; John Zimmerman; Sascha Migura; Bernhard Kneer; Jens Timo Neumann; Winfried Kaiser
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Paper Abstract

EUV lithography for resolution below 8 nm half pitch requires the numerical aperture (NA) of the projection lens to be significantly larger than the current state-of-the-art 0.33NA. In order to be economically viable, a throughput in the range of 100 wafers per hour is needed. As a result of the increased NA, the incidence angles of the light rays at the mask increase significantly. Consequently the shadowing and the variation of the multi-layer reflectivity deteriorate the aerial image contrast to unacceptably low values at the current 4x magnification. The only solution to reduce the angular range at the mask is to increase the magnification. Simulations show that we have to double the magnification to 8x in order to overcome the shadowing effects. Assuming that the mask infrastructure will not change the mask form factor, this would inevitably lead to a field size that is a quarter of the field size of current 0.33NA step and scan systems. This would reduce the throughput of the high-NA scanner to a value significantly below 100 wafers per hour unless additional measures are taken. This paper presents an anamorphic step and scan system capable to print fields that are half the field size of the current full field. The anamorphic system has the potential to achieve a throughput in excess of 150 wafers per hour by increasing the transmission of the optics as well as increasing the acceleration of the wafer stage and mask stage. This makes it an economically viable lithography solution. The proposed 4x/8x magnification is not the only logical solution. There are potentially other magnifications to increase the scanner performance while at the same time reducing the mask requirements.

Paper Details

Date Published: 16 November 2015
PDF: 14 pages
Proc. SPIE 9635, Photomask Technology 2015, 963503 (16 November 2015); doi: 10.1117/12.2202258
Show Author Affiliations
Jan van Schoot, ASML Netherlands B.V. (Netherlands)
Koen van Ingen Schenau, ASML Netherlands B.V. (Netherlands)
Gerardo Bottiglieri, ASML Netherlands B.V. (Netherlands)
Kars Troost, ASML Netherlands B.V. (Netherlands)
John Zimmerman, ASML (United States)
Sascha Migura, Carl Zeiss SMT GmbH (Germany)
Bernhard Kneer, Carl Zeiss SMT GmbH (Germany)
Jens Timo Neumann, Carl Zeiss SMT GmbH (Germany)
Winfried Kaiser, Carl Zeiss SMT GmbH (Germany)


Published in SPIE Proceedings Vol. 9635:
Photomask Technology 2015
Naoya Hayashi, Editor(s)

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