Effects of H2 impregnation on excimer-laser-induced oxygen-deficient center formation in synthetic SiO2 glass

We examined the effect of ${\mathrm{H}}_2$ impregnation on defect formation upon ${\mathrm{F}}_2$ laser (7.9 eV) and ArF excimer laser (6.4 eV) irradiation. It was revealed that ${\mathrm{H}}_2$ impregnation enhanced the formation of oxygen-deficient center (Si–Si bond) as well as suppressed the formation of $E^{\prime }$ center and nonbridging oxygen hole center. A Si–Si bond gives an intense absorption band peaking at 7.6 eV, which contributes the absorption at the wavelength of ${\mathrm{F}}_2$ laser light. These results indicate that ${\mathrm{H}}_2$ -free ${\mathrm{SiO}}_2$ glass, which is clearly inappropriate for KrF and ArF excimer laser optics, is more suitable for ${\mathrm{F}}_2$ laser optics than ${\mathrm{H}}_2$ -impregnated glass.