Abstract

New microlithography tools that are currently coming into production use are based on the ArF excimer laser which operates at a wavelength of approximately 1935 Å (51680 cm⁻¹). Because of the difficulty of producing large aperture achromatic projection optics at this wavelength, it is essential that the laser wavelength be stabilized and known to a high degree of accuracy. Methods for measuring the laser wavelength have been developed using the optogalvanic effect to observe accurately known atomic spectral lines in sealed hollow cathode discharge lamps. We set out to measure seven lines of Fe I, Ge I and Pt I within the tuning range of the ArF laser that can be observed optogalvanically and are suitable as wavelength standards. In the course of this study we compared wavelength calibrations derived from Fe I, Fe II, Ge I and Cu II lines and found small but statistically significant differences. We also made accurate new measurements for Pt I and II and Kr II in the region 1800 Å to 3100 Å.

© 2003 Optical Society of America