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Proceedings Paper

Impact of an etched EUV mask black border on imaging: part II
Author(s): Natalia Davydova; Robert de Kruif; Hiroaki Morimoto; Yo Sakata; Jun Kotani; Norihito Fukugami; Shinpei Kondo; Tomohiro Imoto; Brid Connolly; Dries van Gestel; Dorothe Oorschot; David Rio; John Zimmerman; Noreen Harned
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Paper Abstract

The image border is a pattern free dark area around the die on the photomask serving as transition area between the parts of the mask that is shielded from the exposure light by the Reticle Masking (ReMa) blades and the die. When printing a die at dense spacing on an EUV scanner, the reflection from its image border overlaps with the edges of neighboring dies affecting CD and contrast in this area. This is related to the fact that EUV absorber stack has 1-3% reflectance for actinic light. For a 55nm thick absorber the induced CD drop at the edges is found to be 4-5 nm for 27 nm dense lines. In this work we will show an overview of the absorber reflection impact on CD at the edge of the field across EUV scanner generations, for several imaging nodes and multiple absorber heights. Increasing spacing between dies on the wafer would prevent the unwanted exposure but results in an unacceptable loss of valuable wafer real estate thereby reducing the yield per wafer and is thus not a viable manufacturing solution. In order to mitigate the reflection from the image border one needs to create a so called black border. The most promising approach is removal of the absorber and the underlying multilayer down to the low reflective LTEM substrate by multilayer etching. It was shown in the previous study that the impact on CD was reduced essentially for 27 nm dense lines exposed on ASML NXE:3100. In this work we will continue the study of a multilayer etched black border impact on imaging. In particular, 22 nm lines/spaces imaging on ASML NXE:3300 EUV scanner will be investigated in the areas close to the black border as well as die to die effects. We will look closer into the CD uniformity impact by DUV Out-of-Band light reflected from black border and its mitigation. A possible OPC approach will also be evaluated.

Paper Details

Date Published: 3 October 2013
PDF: 12 pages
Proc. SPIE 8880, Photomask Technology 2013, 888027 (3 October 2013); doi: 10.1117/12.2027596
Show Author Affiliations
Natalia Davydova, ASML Netherlands B.V. (Netherlands)
Robert de Kruif, ASML Netherlands B.V. (Netherlands)
Hiroaki Morimoto, Toppan Printing Co., Ltd. (Japan)
Yo Sakata, Toppan Printing Co., Ltd. (Japan)
Jun Kotani, Toppan Printing Co., Ltd. (Japan)
Norihito Fukugami, Toppan Printing Co., Ltd. (Japan)
Shinpei Kondo, Toppan Printing Co., Ltd. (Japan)
Tomohiro Imoto, Toppan Printing Co., Ltd. (Japan)
Brid Connolly, Toppan Photomasks, Inc. (Germany)
Dries van Gestel, ASML Netherlands B.V. (Netherlands)
Dorothe Oorschot, ASML Netherlands B.V. (Netherlands)
David Rio, ASML US Inc. (United States)
John Zimmerman, ASML Wilton (United States)
Noreen Harned, ASML Wilton (United States)

Published in SPIE Proceedings Vol. 8880:
Photomask Technology 2013
Thomas B. Faure; Paul W. Ackmann, Editor(s)

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