Ultra line-narrowed ArF excimer laser G42A for sub-90-nm lithography generation

193-nm lithography is going to move from pre-production phase to mass production phase and its target node become narrowing from 90 nm to 65 nm. In these situations, the laser manufacture needs to provide the high durable ArF excimer laser, which has superior spectrum performance. Gigaphoton has already introduced 4 kHz ArF laser (model G41A) to 193-nm lithography market, which produce 20 W and spectrum bandwidth of 0.35 pm (FWHM). G41A has showed high reliability and long lifetime over 5 billion pulses. In this paper, we report on the 4 kHz ArF excimer laser for mass production, model G42A, which has 20 W, spectral bandwidth less than 0.3 pm (FWHM) and a spectral purity less than 0.75 pm (E95).