High-power 193-nm excimer lasers for DUV lithography

High output power and ultra-narrow bandwidth has been the development goals for the 193 nm lithography excimer lasers in the last years to support the throughput and requirements of advanced 193 nm wafer scanner. Cost of ownership comparable to current 248 nm lithography wafer scanner is one of the important prerequisites for the economic implementation of 193 nm lithography in production. In this paper we present the performance results of our new high power ArF lithography excimer lasers with repetition rate of 4 kHz. The laser delivers a stabilized output power of up to 40 W. The spectral laser output is matched to the requirements of high NA catadioptric imaging lenses with a bandwidth of less than 25 pm, FWHM. The new laser delivers energy dose stability of less than 0.35% for a 50 pulse dose window. Second part of the paper gives the status of the ultra-narrow bandwidth 193 nm excimer laser for refractive imaging lenses. A spectral bandwidth of less than 0.35 pm, FWHM, has been achieved with a spectral purity of less than 0.95 pm. Results from the laser operating at 2 kHz are presented. The performance characteristics at of he line-narrowed 193 nm laser with 4 kHz repetition rate are presented. Finally an outlook on the achievement of ultra-narrow-bandwidth 193 nm excimer lasers for micro-lithography will be given.