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Proceedings Paper

Characterization of absorptance losses in optical materials using a high resolution Hartmann-Shack wavefront sensor
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Paper Abstract

Lens heating due to absorbed UV laser radiation can diminish the achievable spatial resolution of the lithographic process in semiconductor wafer steppers. At the Laser- Laboratorium Göttingen a measurement system for quantitative registration of this thermal lens effect was developed. It is based upon a strongly improved Hartmann-Shack wavefront sensor with extreme sensitivity, accomplishing precise online monitoring of wavefront deformations of a collimated test laser beam transmitted through the laser-irradiated site of a sample. Caused by the temperature-dependent refractive index as well as thermal expansion, the formerly plane wavefront of the test laser is distorted to form a rotationally symmetric valley, being equivalent to a convex lens. The observed wavefront distortion is a quantitative measure of the absorption losses in the sample. Thermal theory affords absolute calibration of absorption coefficients.

Paper Details

Date Published: 14 February 2008
PDF: 9 pages
Proc. SPIE 6879, Photon Processing in Microelectronics and Photonics VII, 68791S (14 February 2008); doi: 10.1117/12.762579
Show Author Affiliations
A. Bayer, Laser-Lab. Göttingen e.V. (Germany)
F. Barkusky, Laser-Lab. Göttingen e.V. (Germany)
U. Leinhos, Laser-Lab. Göttingen e.V. (Germany)
T. Miege, Laser-Lab. Göttingen e.V. (Germany)
B. Schäfer, Laser-Lab. Göttingen e.V. (Germany)
K. Mann, Laser-Lab. Göttingen e.V. (Germany)


Published in SPIE Proceedings Vol. 6879:
Photon Processing in Microelectronics and Photonics VII
David B. Geohegan; Frank Träger; Jan J. Dubowski; Andrew S. Holmes; Michel Meunier; Craig B. Arnold; Hiroyuki Niino, Editor(s)

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