Liquid-Xenon-Jet Laser-Plasma Source for EUV Lithography

The liquid-xenon-jet laser-plasma source is one of the extreme-ultraviolet (EUV) source technologies under development for EUV lithography. This paper discuss the basic,demanding,requirements of a source for EUV lithography including high in-band EUV power,absence of mirror contamination and high stability. It is further discussed how the liquid-xenon-jet can meet these requirements,and specifically how the ability to operate the plasma far from any mechanical details such as the nozzle will facilitate high power operation with low resulting mirror degradation. Furthermore,a new laser-to-EUV conversion efficiency result of 0.55 %/(2%BW 2 πsr) at λ=13.45 nm is presented together with a detailed description of the method for calibrated EUV-power measurement.