|Title||Laser-Plasma Sources for Soft-X-Ray Projection Lithography|
|Publication Type||Journal Article|
|Year of Publication||1994|
|Authors||F. Bijkerk, L. Shmaenok, A. Vanhonk, R. Bastiaensen, Y.Y Platonov, A.P Shevelko, A.V Mitrofanov, F. Voss, R. Desor, H. Frowein, B. Nikolaus|
|Journal||Journal De Physique Iii|
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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