Abstract
The effect of small amounts of gaseous additives and impurities on ArF laser performance has been studied. It has been found that the output characteristics of the ArF laser improves significantly at a xenon concentration of 10 ppm but strongly deteriorates at impurity concentrations above 10 ppm of e.g. O2, CF4 and HF, especially, at high laser repetition rates. A new laser discharge chamber has therefore been developed using metal seals and coating the inner chamber walls with thin fluoride layers. The layers prevent impurities that are otherwise generated through chemical reactions between the fluorine of the laser gas and the chamber wall. The output stability of the ArF excimer laser has been very successfully improved by the new chamber design for repetition rates up to 4 kHz.
