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Proceedings Paper

Fabrication of aspherical mirrors for EUV projection optics set-3 of HiNA
Author(s): Tetsuya Oshino; Shin-ichi Takahashi; Takahiro Yamamoto; Tatsuro Miyoshi; Masayuki Shiraishi; Takaharu Komiya; Noriaki Kandaka; Hiroyuki Kondo; Kiyoto Mashima; Kazushi Nomura; Katsuhiko Murakami; Hiroaki Oizumi; Iwao Nishiyama; Shinji Okazaki
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Paper Abstract

We developed a high-numerical-aperture EUV exposure tool (HiNA). HiNA is equipped with an illumination system, projection optics, a mask stage and a wafer stage in the vacuum chamber. The projection optics consist of two aspherical mirrors (M1 and M2). The numerical aperture of the optics is 0.3. Thus far, we fabricated two sets of projection optics (set-1 and set-2). The wavefront errors of set-1 and set-2 were 7.5nm rms and 1.9nm rms, respectively. We developed the third set of projection optics (set-3), the target wavefront error of which was less than 1nm rms. In set-3, we also attempted to reduce flare. We completed the mirror polishing, coating and mirror adjustment of set-3. Using a new polishing method, we successfully reduced low-spatial-frequency roughness (LSFR), mid-spatial-frequency roughness (MSFR) and high-spatial-frequency roughness (HSFR) simultaneously. The predicted wavefront error calculated from the LSFR number was 0.69nm rms. MSFR, which strongly affects the flare of the optics, was significantly reduced to less than 0.2nm rms. The estimated flare was 7%, which is significantly reduced to one-fourth that of set-2. The wavefront error of set-3 was measured with the visible-light point diffraction interferometer (PDI) after coating and assembly. The wavefront error measured after adjustment and cramping of the adjustment system was 0.90nm rms, which is less than one-half the wavefront error of set-2.

Paper Details

Date Published: 18 October 2004
PDF: 10 pages
Proc. SPIE 5533, Advances in Mirror Technology for X-Ray, EUV Lithography, Laser, and Other Applications II, (18 October 2004); doi: 10.1117/12.559210
Show Author Affiliations
Tetsuya Oshino, Nikon Corp. (Japan)
Shin-ichi Takahashi, Nikon Corp. (Japan)
Takahiro Yamamoto, Nikon Corp. (Japan)
Tatsuro Miyoshi, Nikon Corp. (Japan)
Masayuki Shiraishi, Nikon Corp. (Japan)
Takaharu Komiya, Nikon Corp. (Japan)
Noriaki Kandaka, Nikon Corp. (Japan)
Hiroyuki Kondo, Nikon Corp. (Japan)
Kiyoto Mashima, Nikon Corp. (Japan)
Kazushi Nomura, Nikon Corp. (Japan)
Katsuhiko Murakami, Nikon Corp. (Japan)
Hiroaki Oizumi, Association of Super-Advanced Electronics Technologies (Japan)
Iwao Nishiyama, Association of Super-Advanced Electronics Technologies (Japan)
Shinji Okazaki, Association of Super-Advanced Electronics Technologies (Japan)

Published in SPIE Proceedings Vol. 5533:
Advances in Mirror Technology for X-Ray, EUV Lithography, Laser, and Other Applications II
Ali M. Khounsary; Udo Dinger; Kazuya Ota, Editor(s)

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