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Proceedings Paper

Novel EUV mask black border suppressing EUV and DUV OoB light reflection
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Paper Abstract

EUV lithography is the most promising technology for semiconductor device manufacturing of the 10nm node and beyond. 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 the image border overlaps edges of neighboring dies, affecting CD and contrast in this area. This is related to the fact that EUV absorber stack reflects 1-3% of actinic EUV light. To reduce this effect several types of image border with reduced EUV reflectance (<0.05%) have been proposed; such an image border is referred to as a black border. In particular, an etched multilayer type black border was developed; it was demonstrated that CD impact at the edge of a die is strongly reduced with this type of the black border (BB). However, wafer printing result still showed some CD change in the die influenced by the black border reflection. It was proven that the CD shift was caused by DUV Out of Band (OOB) light from the EUV light source. New types of a multilayer etched BB were evaluated and showed a good potential for DUV light suppression. In this study, a novel BB called ‘Hybrid Black Border’ (HBB) has been developed to eliminate EUV and DUV OOB light reflection by applying optical design technique and special micro-fabrication technique. A new test mask with HBB is fabricated without any degradation of mask quality according to the result of CD performance in the main pattern, defectivity and cleaning durability. The imaging performance for N10 imaging structures is demonstrated on NXE:3300B in collaboration with ASML. This result is compared to the imaging results obtained for a mask with the earlier developed BB, and HBB has achieved ~3x improvement; less than 0.2 nm CD changes are observed in the corners of the die. A CD uniformity budget including impact of OOB light in the die edge area is evaluated which shows that the OOB impact from HBB becomes comparable with other CDU contributors in this area. Finally, we state that HBB is a promising technology allowing for CD control at die edges.

Paper Details

Date Published: 10 May 2016
PDF: 10 pages
Proc. SPIE 9984, Photomask Japan 2016: XXIII Symposium on Photomask and Next-Generation Lithography Mask Technology, 99840O (10 May 2016); doi: 10.1117/12.2242624
Show Author Affiliations
Shin Ito, Toppan Printing Co., Ltd. (Japan)
Yutaka Kodera, Toppan Printing Co., Ltd. (Japan)
Norihito Fukugami, Toppan Printing Co., Ltd. (Japan)
Toru Komizo, Toppan Printing Co., Ltd. (Japan)
Shingo Maruyama, Toppan Printing Co., Ltd. (Japan)
Genta Watanabe, Toppan Printing Co., Ltd. (Japan)
Itaru Yoshida, Toppan Printing Co., Ltd. (Japan)
Jun Kotani, Toppan Printing Co., Ltd. (Japan)
Toshio Konishi, Toppan Printing Co., Ltd. (Japan)
Takashi Haraguchi, Toppan Printing Co., Ltd. (Japan)

Published in SPIE Proceedings Vol. 9984:
Photomask Japan 2016: XXIII Symposium on Photomask and Next-Generation Lithography Mask Technology
Nobuyuki Yoshioka, Editor(s)

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