Mass-limited, debris-free laser-plasma EUV source

The development of a laser-plasma EUV line emission source based on frozen water droplet targets which is essentially debris-free and capable of continuous, high-repetition-rate ( \u3e 1 kHz) operation is described. Created by modest ( \u3c 1 J) laser energies, this plasma produces copious emission at 13 and 11.6 nm, the preferred wavelengths for EUV projection lithography, with negligible target operation costs. (C) 1998 Elsevier Science B.V