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Proceedings Paper

Properties of EUV and particle generations from laser-irradiated solid- and low-density tin targets
Author(s): Shinsuke Fujioka; Hiroaki Nishimura; Tomoharu Okuno; Yezheng Tao; Nobuyoshi Ueda; Tsuyoshi Ando; Hiroto Kurayama; Yuzuri Yasuda; Shigeaki Uchida; Yoshinori Shimada; Michiteru Yamaura; Qincui Gu; Keiji Nagai; Takayoshi Norimatsu; Hiroyuki Furukawa; Atsushi Sunahara; Young-G. Kang; Masakatsu Murakami; Katsunobu Nishihara; Noriaki Miyanaga; Yasukazu Izawa
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Paper Abstract

Properties of laser-produced tin (Sn) plasmas were experimentally investigated for application to the Extreme Ultra-Violet (EUV) lithography. Optical thickness of the Sn plasmas affects strongly to EUV energy, efficiency, and spectrum. Opacity structure of uniform Sn plasma was measured with a temporally resolved EUV spectrograph coupled with EUV backlighting technique. Dependence of the EUV conversion efficiency and spectra on Sn target thickness were studied, and the experimental results indicate that control of optical thickness of the Sn plasma is essential to obtain high EUV conversion efficiency and narrow spectrum. The optical thickness is able to be controlled by changing initial density of targets: EUV emission from low-density targets has narrow spectrum peaked at 13.5 nm. The narrowing is attributed to reduction of satellite emission and opacity broadening in the plasma. Furthermore, ion debris emitted from the Sn plasma were measured using a charge collector and a Thomson parabola ion analyzer. Measured ablation thickness of the Sn target is between 30 and 50 nm for the laser intensity of 1.0 x 1011 W/cm2 (1.064 μm of wavelength and 10 ns of pulse duration), and the required minimum thickness for sufficient EUV emission is found to be about 30 nm under the same condition. Thus almost all debris emitted from the 30 nm-thick mass-limited Sn targets are ions, which can be screened out by an electro-magnetic shield. It is found that not only the EUV generation but also ion debris are affected by the Sn target thickness.

Paper Details

Date Published: 6 May 2005
PDF: 10 pages
Proc. SPIE 5751, Emerging Lithographic Technologies IX, (6 May 2005); doi: 10.1117/12.598692
Show Author Affiliations
Shinsuke Fujioka, Institute of Laser Engineering, Osaka Univ. (Japan)
Hiroaki Nishimura, Institute of Laser Engineering, Osaka Univ. (Japan)
Tomoharu Okuno, Institute of Laser Engineering, Osaka Univ. (Japan)
Yezheng Tao, Institute of Laser Engineering, Osaka Univ. (Japan)
Nobuyoshi Ueda, Institute of Laser Engineering, Osaka Univ. (Japan)
Tsuyoshi Ando, Institute of Laser Engineering, Osaka Univ. (Japan)
Hiroto Kurayama, Institute of Laser Engineering, Osaka Univ. (Japan)
Yuzuri Yasuda, Institute of Laser Engineering, Osaka Univ. (Japan)
Shigeaki Uchida, Institute for Laser Technology (Japan)
Yoshinori Shimada, Institute for Laser Technology (Japan)
Michiteru Yamaura, Institute for Laser Technology (Japan)
Qincui Gu, Institute of Laser Engineering, Osaka Univ. (Japan)
Keiji Nagai, Institute of Laser Engineering, Osaka Univ. (Japan)
Takayoshi Norimatsu, Institute of Laser Engineering, Osaka Univ. (Japan)
Hiroyuki Furukawa, Institute for Laser Technology (Japan)
Atsushi Sunahara, Institute for Laser Technology (Japan)
Young-G. Kang, Institute of Laser Engineering, Osaka Univ. (Japan)
Masakatsu Murakami, Institute of Laser Engineering, Osaka Univ. (Japan)
Katsunobu Nishihara, Institute of Laser Engineering, Osaka Univ. (Japan)
Noriaki Miyanaga, Institute of Laser Engineering, Osaka Univ. (Japan)
Yasukazu Izawa, Institute of Laser Engineering, Osaka Univ. (Japan)


Published in SPIE Proceedings Vol. 5751:
Emerging Lithographic Technologies IX
R. Scott Mackay, Editor(s)

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