| 摘要 |
PROBLEM TO BE SOLVED: To narrow the band of an ArF excimer laser for exposing semiconductor by finding out the condition for narrowing a spectrum line width (95% integrated line width) to <=1.15 pm by using the conventional narrowed-band optical system composed of beam diameter expanding prisms and a diffraction grating. SOLUTION: The ArF excimer laser is provided with a band-narrowed optical system, composed of a Littrow mounting echelle diffraction grating, beam diameter expanding prisms 5 composed of three prisms arranged on the incident side of the grating 3, and a slit 4 and the blaze angleθof the grating 3 is adjusted to be 82 deg. or smaller. In addition, magnification M of the prism 5 is adjusted to 26 times or smaller and a oscillating pulse width Tis of the laser is adjusted to 60 ns or shortes. Moreover, length L of a resonator is adjusted to 1,000-1,350 mm and the width W of the slit 4 is adjusted to 1.0 mm or longer, so that the relation (w+11)cosθ/(LMTis0.853)<4.94×10-6 is satisfied among them. |
