Patent ID: 6783898
Filing Date: 2004-08-31
Classification: C03B,C03C,G03F

Abstract:
A method of making a lithography photomask blank, comprising the steps of:providing a soot deposition surface, producing a plurality of SiO2 soot particles and projecting said SiO2 soot particles towards said soot deposition surface, successively depositing said SiO2 soot particles on said deposition surface to form a coherent SiO2 porous glass preform body, dehydrating said coherent SiO2 glass preform body to remove OH from said coherent SiO2 glass preform body, exposing said SiO2 to a fluorine containing atmosphere and consolidating the coherent SiO2 glass preform body into a silicon oxyfluoride glass body having less than 1Ã—1017 H2 molecules/cm3, forming said consolidated silicon oxyfluoride glass body into a photomask blank having less than 1Ã—1017 H2 molecules/cm3 and a planar surface.