EUV radiation characteristics of a CO_2 laser produced Xe plasma

摘要

A CO_2 laser-driven Xe liquid jet plasma has been studied with respect to its usability as a EUV lithography light source. A short-pulse TEA-CO_2 master oscillator power amplifier system (MOPA) and a pre-pulse Nd:YAG laser were used for the plasma generation. The dependence of EUV plasma parameters, e.g., conversion efficiency, plasma image, in-band and out-of-band spectra, on the delay time between the pre-pulse and the main pulse laser was investigated. A maximum conversion efficiency of 0.6% was obtained at a delay time of about 200 ns. In addition, characteristics of fast ions were measured by the time-of-flight method. The peak energy of the fast ion energy distribution decreased significantly at delay times longer than 200 ns. This result is very promising with respect to a collector mirror lifetime extension by magnetic field mitigation.