Effects of fluorine dimer excimer laser radiation on the optical transmission and defect formation of various types of synthetic SiO2 glasses

Abstract

Changes in the optical absorption and the formation of point defects in three types of synthetic SiO2 glasses, wet (OH content; 120 ppm), dry (OH content <1 ppm), and fluorine (F)-doped (∼1 mol %) SiO2 glasses, by irradiation with fluorine dimer (F2) excimer laser light pulses (∼8 mJ/cm2/pulse×3.6×105 pulses) were examined by various spectroscopic methods. Intense optical absorptions were induced in the wet and dry silicas in the range of 4–8 eV, whereas the intensity of absorptions induced in the F-doped silica was smaller by an order of magnitude than that in the F-free glasses. The optical transmission at the wavelength of 157 nm after the irradiation was F-doped silica≫wet silica>dry silica. The dominant electron spin resonance-active defect in the irradiated specimens was the nonbridging oxygen-hole center (NBOHC) for the wet silica, or the E′ center in the dry silica. The concentration of NBOHCs or E′ centers in the F-doped silica was lower by an order of magnitude than that in the wet or dry silica. The present results suggest the possibility of using F-doped silica glasses as photomask materials for F2 laser lithography.

Defects in oxide glasses

“…The suggested mechanism of this phenomenon is the stabilization of radiation-created oxygen interstitials by transforming them to silanol bonds. A dramatic improvement of VUV transparency and excimer laser toughness takes place [65] in silica glass doped by fluorine (≈0.1-1 wt%). Fluorine is incorporated in silica mainly [66] in the form of SiF groups, which help to relax the silica network by building into the strained sites (Fig.…”

Doping effects in amorphous oxides

“…In 1980s, such F-doping effects had attracted much attention for fiber applications. Then, it was also found that F-doping improves the resistance to vacuum-ultraviolet (UV) light (<200 nm) 21) and gammaray irradiation, 23)25) and silica glass became available as optical materials for vacuum-UV applications, as shown in Fig. 3.…”

“…ppm F-doping. 49) Hosono et al 21) examined the radiation toughness of several silica glasses; F-doped silica glass, dry silica glass (the SiOH content <1 ppm), and wet silica glass (the SiOH content ³120 ppm). The concentration of the residual OH bond in the F-doped glass was close to that in the dry silica glass.…”

Long-lasting phosphorescence in Mn2+:Zn2GeO4crystallites precipitated in transparent GeO2–B2O3–ZnO glass-ceramics

“…In general, such point defects result in undesirable degradation of electrical and/or optical properties, but they can also be used to exhibit some specific features or applications. A variety of metastable defects in glasses have been observed under an excimer laser and a femtosecond laser induces a variety of metastable defects [1][2][3]. It is hence likely that some novel optical functions can be elicited if the characteristics and quantities of the defects can be controlled.…”