The liquid-xenon-jet laser-plasma EUV source is one of the source types under development for EUVL. This chapter focuses on the initial development of the source type performed by the authors and their coworkers at the Royal Institute of Technology (KTH) and at the former company Innolite AB, both in Stockholm, Sweden. Where relevant, it also presents results on this source type achieved by others; results given without specific references were obtained at KTH or Innolite AB.
Synchrotron radiation from electron storage rings is today the most common source of EUV radiation. However, it is difficult to install an electron storage ring in an existing fab, especially given the required radiation shielding, which weighs at least 100–200 tons. Furthermore, a traditional synchrotron source cannot meet the power requirements of EUVL. Instead, all sources under consideration for EUVL are based on hot plasmas, and there are two major ways to generate the plasma: electrical discharge and laser irradiation. Since the various electrical-discharge sources are covered elsewhere in this volume, this chapter will mainly discuss the laser plasma. It should also be mentioned that other means to generate EUV radiation are available, including high-harmonic generation, table-top soft-x-ray lasers, and conventional electron impact sources, but since they are not expected to reach the specifications for EUVL, they are not discussed further here.
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