Oxygen doping of silicon oxyfluoride glass

摘要

High purity silicon oxyfluoride glass suitable for use as a photomask substrate for photolithography applications is disclosed in the VUV wavelength region of less than 190 nm. Doped glass (20) is produced by providing a O ₂ doping atmosphere (26) in the silicon oxyfluoride glass in doping container (28) (22). Silicon oxyfluoride glass of the present invention is transparent at the wavelength of 157nm Atari, Therefore, it is particularly useful as a photomask substrate in 157nm wavelength region. Photomask substrate of the present invention contains a doped O ₂ molecule is a "dry" silicon oxyfluoride glass exhibit very high transmittance and laser transmitting durability in a vacuum ultraviolet (VUV) wavelength region. Containing fluorine, in addition to OH content with little or no, silicon oxyfluoride glass of the present invention contains an interstitial O ₂ molecules for improving the resistance to laser exposure. Preferably, O ₂ doped silicon oxyfluoride glass is characterized by having a 1 × 10 ¹⁷ mol / cm ³ less than the hydrogen molecules and the low levels of chlorine.