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Proceedings Paper

Development for the alignment procedure of three-aspherical mirror optics
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Paper Abstract

Extreme ultraviolet lithography (EUVL) is one of the candidates to fabricate a sub-0.1 micrometer-pattern. We have developed an Engineering Test Stand (ETS-0) which consists of three aspherical mirrors imaging optics for EUVL. This optics meets the specification of sub-0.1 micrometer generation. The key technology of EUVL is a development of reduction optics. The requirements of both figure error and surface roughness are less than 0.3 nm, and the wave-front error (WFE) of optical system has to be reached to be less than (lambda) /14 rms, where (lambda) is the exposure wavelength. Therefore, the high-precision fabrication and alignment techniques for the optics are required. We have developed the alignment procedure of three-aspherical-mirror optics to minimize the WFE, by the Fizeau-type interferometer using He-Ne laser ((lambda) equals 632.8 nm) and by the ray trace program (CODE-V). Namely, we have found the effective mirror-adjustment-axis to realize the high-precision alignment. The effective axis is decided by the priority for the adjustment axis. The priority is lead by two methods. One method is decided by the contribution to the WFE reduction that was calculated by CODE-V. The other method is decided by the correlation between the amount of decentration (shift for X-axis or Y-axis direction), despacing (shift for Z-axis direction), tilt of each mirror and the F.Z.- coefficients. The mirror is adjusted in the order of the priority of mirror axis. As a result, the WFE of 3 nm RMS has been achieved by using this alignment procedure in three- aspherical-mirror optics.

Paper Details

Date Published: 21 July 2000
PDF: 7 pages
Proc. SPIE 3997, Emerging Lithographic Technologies IV, (21 July 2000); doi: 10.1117/12.390122
Show Author Affiliations
Shigeo Irie, Matsushita Electronics Corp (Japan)
Takeo Watanabe, Himeji Institute of Technology (Japan)
Hiroo Kinoshita, Himeji Institute of Technology (Japan)
Atsushi Miyafuji, Himeji Institute of Technology (Japan)
Katsumi Sugisaki, Nikon Corp. (Japan)
Tetsuya Oshino, Nikon Corp. (Japan)
Katsuhiko Murakami, Nikon Corp. (Japan)

Published in SPIE Proceedings Vol. 3997:
Emerging Lithographic Technologies IV
Elizabeth A. Dobisz, Editor(s)

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