OPTICAL MATERIAL OF SYNTHETIC QUARTZ GLASS FOR F2 EXCIMER LASER AND OPTICAL PART

摘要

PROBLEM TO BE SOLVED: To provide an optical material of a synthetic quartz glass wherein the optical transmission at 157 nm which is the oscillation wavelength of a F2 excimer laser is high, resistance to the laser irradiation is high and the homogeneity inherent in the fine line lithography using the laser is realized, and the optical part using the material. SOLUTION: In the optical material, the OH group concentration, the fluorine concentration and the hydrogen molecule concentration of the optical material are <=0.5 ppm, 0.1-2 mol% and <=5×1016 mol/cm3, respectively. The difference in the fluorine concentration between a maximum and a minimum is <=20 mol ppm and the difference in refractive index between a maximum and a minimum is <=2×10-5.