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Journal of Micro/Nanolithography, MEMS, and MOEMS • Open Access

Improvement of defects and flatness on extreme ultraviolet mask blanks
Author(s): Tsutomu Shoki; Masato Ootsuka; Minoru Sakamoto; Tatsuo Asakawa; Ryuuji Sakamoto; Hirofumi Kozakai; Kazuhiro Hamamoto; Takahiro Onoue; Toshihiko Orihara; Osamu Maruyama; Jun-Ichi Horikawa

Paper Abstract

We have improved flatness and defects on an extreme ultraviolet (EUV) blank, which are critical issues for implementing EUV lithography. A high flatness of less than 30 nm on a glass substrate and low defects over 22 nm sphere-equivalent-volume-diameter (SEVD) on a multilayer (ML) blank are required for 22 nm half-pitch process. Flatness quality was improved to an average of around 50 nm and 30 nm as best, through more precise polishing process. Defect quality of single digit over 60 nm was achieved by improvement of fabrication process. New defect inspection was started for further defect reduction using a Teron Phasur. It was confirmed that there are lots of real phase defects with low height of less than 2 nm on a ML blank captured by the Teron. Small defects over 25 nm SEVD have been dramatically reduced to 20 defects mainly by various improvements of fabrication processes. A gap in flatness and defects between actual quality and the requirement is getting small, and both the qualities will be improved further for near future production.

Paper Details

Date Published: 1 April 2013
PDF: 7 pages
J. Micro/Nanolith. MEMS MOEMS 12(2) 021008 doi: 10.1117/1.JMM.12.2.021008
Published in: Journal of Micro/Nanolithography, MEMS, and MOEMS Volume 12, Issue 2
Show Author Affiliations
Tsutomu Shoki, HOYA Corp. (Japan)
Masato Ootsuka, HOYA Corp. (Japan)
Minoru Sakamoto, HOYA Corp. (Japan)
Tatsuo Asakawa, HOYA Corp. (Japan)
Ryuuji Sakamoto, HOYA Corp. (Japan)
Hirofumi Kozakai, HOYA Corp. (Japan)
Kazuhiro Hamamoto, HOYA Corp. (Japan)
Takahiro Onoue, HOYA Corp. (Japan)
Toshihiko Orihara, HOYA Corp. (Japan)
Osamu Maruyama, HOYA Corp. (Japan)
Jun-Ichi Horikawa, HOYA Corp. (Japan)

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