Study of the generation of the 13.5-nm EUV radiation from Sn ions in a CO2 laser-produced plasma

Results are presented from experimental and theoretical studies of the efficiency of using a CO2 laser to create a high-power source of 13- to 14-nm EUV radiation for lithography. For a laser intensity of ∼2 × 1011 W/cm2, a conversion efficiency of k EUV ≃ 1.5% was achieved on a plane solid Sn target. The calculated gas dynamics and population kinetics of Sn plasma ions agree qualitatively with experimental results.