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Proceedings Paper

Compact laser-induced EUV source for metrology
Author(s): Klaus Mann; F. Barkusky; Stefan Doering; Sebastian Kranzusch; A. Meyer; Christian Peth
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Paper Abstract

At Laser-Laboratorium Goettingen different types of laser-plasma EUV sources based on gas and cluster targets were tested to optimize the spatially resolved EUV radiation with respect to maximum EUV intensities, small source diameters, and pointing stability. The EUV radiation is generated by focusing a Q-switched Nd:YAG laser at 1064nm into a pulsed gas puff target. By the use of different target gases, broad-band as well as narrow-band EUV radiation is obtained, respectively. The influence of the laser and target gas parameters on the plasma shape and EUV intensity was investigated by the help of specially designed EUV pinhole cameras, utilizing evaluation algorithms developed for standardized laser beam characterization. The properties of the gas jet determine crucial parameters of the source. A directed gas jet in vacuum with a high number density is needed for an optimal performance of the source. Therefore, conical nozzles with different cone angles were drilled with an excimer laser to produce a supersonic gas jet. The influence of the nozzle geometry on the gas jet was analyzed with a Hartmann-Shack wavefront senor, the first time to our knowledge. The deformation of a planar wavefront after passing the gas jet was analyzed with this sensor, out of which the gas density distribution was reconstructed. Thus, the gas jet was optimized resulting in an increase of EUV emission by a factor of two and decreasing the plasma size at the same time.

Paper Details

Date Published: 20 May 2004
PDF: 15 pages
Proc. SPIE 5374, Emerging Lithographic Technologies VIII, (20 May 2004); doi: 10.1117/12.532871
Show Author Affiliations
Klaus Mann, Laser-Lab. Goettingen e.V. (Germany)
F. Barkusky, Laser-Lab. Goettingen e.V. (Germany)
Stefan Doering, Laser-Lab. Goettingen e.V. (Germany)
Sebastian Kranzusch, Laser-Lab. Goettingen e.V. (Germany)
A. Meyer, Laser-Lab. Goettingen e.V. (Germany)
Christian Peth, Laser-Lab. Goettingen e.V. (Germany)

Published in SPIE Proceedings Vol. 5374:
Emerging Lithographic Technologies VIII
R. Scott Mackay, Editor(s)

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