Laser-Plasma Sources for Soft-X-Ray Projection Lithography

TitleLaser-Plasma Sources for Soft-X-Ray Projection Lithography
Publication TypeJournal Article
Year of Publication1994
AuthorsF. Bijkerk, L. Shmaenok, A. Vanhonk, R. Bastiaensen, Y.Y Platonov, A.P Shevelko, A.V Mitrofanov, F. Voss, R. Desor, H. Frowein, B. Nikolaus
JournalJournal De Physique Iii
Date PublishedSep
ISBN Number1155-4320

Results are reported concerning high-repetition-rate excimer lasers with average powers up to 415 W and their usage for generating laser-plasma soft X-ray sources. A conversion efficiency of laser light into monochromatized soft X-ray radiation of 0.7% at 13.5 nm (2% bandwidth) was achieved using an excimer laser of which the beam quality was adapted for this application. Two methods to mitigate the production of plasma debris have been analyzed: tape targets and the use of Kr as a buffer gas. The optimum coating thickness of tape targets coated with Ta has determined to be 1 mum. Ta tape targets and the Kr buffer were used in a debris contamination test of 10(5) pulses. After this exposure, the reflectivity of a normal incidence Mo-Si multilayer mirror that faced the plasma, was found to be 18% lower. The contamination could be removed by cleaning, which restored the reflectivity to 97% of the initial value.



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