High-Efficiency Discharge Excited Rare-Gas Halide Excimer Lasers.

Abstract

Discharge excited rare-gas halide excimer lasers are useful for material processing such as lithography for next generation LSl, laser ablation of polymers and annealing for Si TAT. Among rare-gas halide excimer lasers, three lasers, XeCl, KrF and ArF lasers, are of practical use.In the present paper, basic parameters, which decide the characteristics of these three lasers, are clarified to be the breakdown voltage Vb, excitation duration ts and excitation power density WDE. A guide line to achieve a high oscillation efficiency for the three lasers using a capacitor-transfer-circuit and UV automatic preionization are presented, by considering the three basic parameters. We have obtained a high efficiency of 2.2% for a XeCl laser, 5% for a KrF laser and 2.3% for an ArF laser.The present study is useful to obtain high performance excimer lasers, bacause high-repetition, long-gas-lifetime and compact excimer lasers have been obtained by achieving a high oscillation efficiency.