20 May 2004 Fabrication of aspherical mirrors for HiNA (high numerical aperture EUV exposure tool) set-3 projection optics
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Proceedings Volume 5374, Emerging Lithographic Technologies VIII; (2004); doi: 10.1117/12.562365
Event: Microlithography 2004, 2004, Santa Clara, California, United States
Aspherical mirror fabrication of HiNA set-3 projection optics was completed. By using a new polishing method, we successfully reduced low spatial frequency roughness (LSFR), mid spatial frequency roughness (MSFR) and high spatial frequency roughness (HSFR) compared with HiNA set-1 and set-2 projection optics. MSFR, which strongly affects the flare of the optics, was remarkably reduced to less than 0.2nm rms. HiNA projection optical system with the numerical aperture of 0.3 consists of two aspheric mirrors (M1 and M2). We had already fabricated two sets of the HiNA projection optics. The wavefront error (WFE) of the set-1 optics was 7.5nm rms and that of the set-2 optics was 1.9nm rms. We tried to reduce the WFE and flare in the set-3 optics. The target number of WFE of the set-3 optics was less than 1nm rms. The LSFR, MSFR and HSFR of the M1 of the set-3 optics were 0.25nm rms, 0.17nm rms and 0.10nm rms, respectively. The LSFR and MSFR are almost half values compared with those of the M1 for the set-2 optics. The HSFR was also reduced from 0.13nm rms (set-2) to 0.10nm rms (set-3). The LSFR and MSFR of the M2 were 0.25nm rms and 0.20nm rms, respectively. The estimated wavefront error calculated from these LSFR numbers is 0.7nm rms.
© (2004) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Tetsuya Oshino, Takahiro Yamamoto, Tatsuro Miyoshi, Masayuki Shiraishi, Takaharu Komiya, Noriaki Kandaka, Hiroyuki Kondo, Kiyoto Mashima, Kazushi Nomura, Katsuhiko Murakami, Hiroaki Oizumi, Isa Nishiyama, Shinji Okazaki, "Fabrication of aspherical mirrors for HiNA (high numerical aperture EUV exposure tool) set-3 projection optics", Proc. SPIE 5374, Emerging Lithographic Technologies VIII, (20 May 2004); doi: 10.1117/12.562365; https://doi.org/10.1117/12.562365



Projection systems

Spatial frequencies

Semiconducting wafers


Extreme ultraviolet lithography


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