LONG LIFETIME OPERATION OF AN ARF-EXCIMER LASER

An experimental investigation to improve the lifetime of a discharge-e xcited ArF-excimer laser is presented. The three dominant factors rest ricting its lifetime are CF4 generation in the laser gas, color-center formation in the optics and input power density reduction due to elec trode ablation. Copper electrodes were superior to nickel electrodes i n regard to electrode ablation. A gas lifetime of more than 10(9) shot s (about one month at 400 Hz) is shown for an ArF-excimer laser with a liquid-nitrogen trap and high-temperature zirconium alloy trap.