Mask inspection at the exposure wavelength is set to be a primary contributor to increase yields in tomorrow's fabs as process windows get smaller and smaller. No light source is in sight that could replace future 193nm and 157nm compact excimer lasers for such inspection systems. Tobias pflanz and heinz huber of tuilaser based in germany review the requirements and future opportunities for such compact excimer lasers in optical inspection. Since their first technical realisation in 1976, discharge pumped excimer lasers have found numerous industrial, medical and scientific applications. The fast development of excimer lasers in recent years has succeeded in designing very compact, turn-key systems delivering up to 10W of radiation at 248nm (5W at 193nm and 1W at 157nm) with repetition rates up to lOOOHz. Excimer laser based 193nm (ArF) and 248nm (KrF) photoresist exposure have become established in semiconductor production lines. In the near future mask inspection systems operating at the lithography wavelength will become more and more important in increasing yields in fabs. Another potential application is in maskwriting.
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