The effect of H2 impregnation on defect formation upon F2 laser (7.9eV) and ArF excimer laser (6.4eV) irradiation was examined. It was revealed that H2 impregnation enhanced the formation of O-deficient center (Si-Si bond) as well as suppressed the formation of E’ center and non-bridging O hole center. A Si-Si bond gave an intense absorption band peaking at 7.6eV, which contributes the absorption at the wavelength of F2 laser light. These results indicated that H2-free SiO2 glass, which was clearly inappropriate for KrF and ArF excimer laser optics, was more suitable for F2 laser optics than H2-impregnated glass.

Effects of H2 Impregnation on Excimer Laser-Induced Oxygen-Deficient Center Formation in Synthetic SiO2 Glass. Y.Ikuta, K.Kajihara, M.Hirano, S.Kikugawa, H.Hosono: Applied Physics Letters, 2002, 80[21], 3916-8