UC San Diego

The authors present evidence of the reduction of fast ion energy from laser-produced Sn plasma by introducing a low energy prepulse. The energy of Sn ions was reduced from more than 5 keV to less than 150 eV nearly without loss of the in-band conversion from laser to 13.5 nm extreme ultraviolet (EUV) emission as compared with that of a single pulse. The reason may come from the interaction of the main pulse with preplasma instead of the full density solid surface. This makes it possible to use the full density Sn target in the practical EUV lithography source. (c) 2006 American Institute of Physics.