Energy spectra and charge state of debris emitted from laser-produced minimum mass tin plasmas

Shinsuke Fujioka; Hiroaki Nishimura; Tsuyoshi Ando; Nobuyoshi Ueda; Shinichi Namba; Tatsuya Aota; Masakatsu Murakami; Katsunobu Nishihara; Young-G. Kang; Atsushi Sunahara; Hiroyuki Furukawa; Yoshinori Shimada; Kazuhisa Hashimoto; Michiteru Yamaura; Yuzuri Yasuda; Keiji Nagai; Takayoshi Norimatsu; Noriaki Miyanaga; Yasukazu Izawa; Kunioki Mima

doi:10.1117/12.656071

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24 March 2006 Energy spectra and charge states of debris emitted from laser-produced minimum mass tin plasmas

Shinsuke Fujioka, Hiroaki Nishimura, Tsuyoshi Ando, Nobuyoshi Ueda, Shinichi Namba, Tatsuya Aota, Masakatsu Murakami, Katsunobu Nishihara, Young-G. Kang, Atsushi Sunahara, Hiroyuki Furukawa, Yoshinori Shimada, Kazuhisa Hashimoto, Michiteru Yamaura, Yuzuri Yasuda, Keiji Nagai, Takayoshi Norimatsu, Noriaki Miyanaga, Yasukazu Izawa, Kunioki Mima

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Proceedings Volume 6151, Emerging Lithographic Technologies X; 61513V (2006) https://doi.org/10.1117/12.656071
Event: SPIE 31st International Symposium on Advanced Lithography, 2006, San Jose, California, United States

Abstract

Laser-produced Sn plasma is an efficient extreme ultraviolet (EUV) light source, however the highest risk in the Sn-based EUV light source is contamination of the first EUV collection mirror caused by debris emitted from the Sn plasma. Minimum mass target is a key term associated with relaxation of the mirror contamination problem. For design of the optimum minimum mass Sn target, opacity effects on the EUV emission from the laser-produced Sn plasma should be considered. Optically thinner plasma produced by shorter laser pulse emits 13.5 nm light more efficiently; 2.0% of conversion efficiency was experimentally attained with drive laser of 2.2 ns in pulse duration, 1.0 × 10¹¹ W/cm² in intensity, and 1.064 μm in wavelength. Under the optimum laser conditions, the minimum mass required for sufficient EUV emission, which is also affected by the opacity, is equal to the product of the ablation thickness and the required laser spot size. Emission properties of ionized and neutral debris from laser-produced minimum mass Sn plasmas have been measured with particle diagnostics and spectroscopic method. The higher energy ions have higher charge states, and those are emitted from outer region of expanding plasmas. Feasibility of the minimum mass target has been demonstrated to reduce neutral particle generation for the first time. In the proof-of-principle experiments, EUV emission from a punch-out target is found to be comparable to that from a static target, and expansion energy of ion debris was drastically reduced with the use of the punch-out target.

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Shinsuke Fujioka, Hiroaki Nishimura, Tsuyoshi Ando, Nobuyoshi Ueda, Shinichi Namba, Tatsuya Aota, Masakatsu Murakami, Katsunobu Nishihara, Young-G. Kang, Atsushi Sunahara, Hiroyuki Furukawa, Yoshinori Shimada, Kazuhisa Hashimoto, Michiteru Yamaura, Yuzuri Yasuda, Keiji Nagai, Takayoshi Norimatsu, Noriaki Miyanaga, Yasukazu Izawa, and Kunioki Mima "Energy spectra and charge states of debris emitted from laser-produced minimum mass tin plasmas", Proc. SPIE 6151, Emerging Lithographic Technologies X, 61513V (24 March 2006); https://doi.org/10.1117/12.656071

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