Abstract: This invention is a method for forming fluorine-doped silicate glass having low concentrations of free fluorine atoms. A first embodiment of the invention provides simultaneous deposition of the fluorine-doped glass and scavenging of free fluorine atoms from the surface of the depositing material. A silicon-containing compound, an oxidizer, a fluorine containing compound and a hydrogen-containing gas are introduced into a plasma chemical vapor deposition chamber. A fluorine-doped glass layer having low concentrations of free fluorine atoms deposits. A second embodiment of the invention provides for scavenging of free fluorine atoms from an already-deposited fluorine-doped glass layer by annealing the layer in a forming gas containing hydrogen. The hydrogen gas diffuses into the deposited film and reacts with free fluorine atoms. The hydrogen fluoride so formed migrates through the matrix to the surface of the deposited film, where it is released into the ambient.