Narrow beam ArF excimer laser device

摘要

The invention relates to a semiconductor exposure ArF excimer laser device having a narrow line width containing 95 % of the energy of 1.15 pm or less while using an optical system of prior art beam expansion prisms and a diffraction grating. The ArF excimer laser device for narrowing the bandwidth has a line-narrowing optical system comprised of an echelle diffraction grating 3 in a Littrow arrangement, a beam expansion prism system composed of at least three prisms arranged on the incident side of the echelle diffraction grating, and slits 4. The blaze angle &thetas; of the diffraction grating 3 is 82 DEG or less, the magnification rate M of the beam expansion prism system is 26 times or less, the oscillation pulse width Tis is 60 ns or less, the length L of the resonator is in a range of 1000 to 1350 mm and the slit width W is 1.0 mm or more, satisfying relation (W + 11) cos&thetas;/(LMTis<0.853>) < 4.94 x 10<-6> . <IMAGE>