High-NA high-throughput scanner compatible 2 kHz KrF excimer laser for DUV lithography

We have succeeded in the development of an excimer laser with ultra narrow bandwidth applicable to high N.A. scanners targeting on the 0.13 mu m-design rule. Key word of our solution for 0.13 mu m-design rule was "extended technologies of currently available KrF excimer laser unit (model G20K)". As the result we could shorten development time remarkably. The narrower the laser spectrum, the less the influence of chromatic aberration on exposure projection lens; this is a well-known fact. We have developed the technologies to achieve spectral bandwidth less than 0.5pm, 20% narrower than our current model G20K. In order to attain this number, the major design change was made on line narrowing module, which was redesigned to minimize the dispersion of wavelength element. In addition gas condition was fine-tuned for the new line narrowing module. Integrated energy stability has been improved within +/-0.35% with 35pulses window by the introduction of a high efficiency pulse power module and a faster gas circulation system. The rest of oscillation performances and durability equate with the base model G20K. The intelligent gas control system extended gas exchange interval up to 200 million pulses or 7 days. The G20K already passed through 10 billion-pulse test. Total energy loss was within 4mJ which is small enough to be compensated by gas injection and voltage change; it is a unique compensation system of Komatsu.