Behavior of Fluorine Atoms in a-Si:F:H Alloy Investigated by Gas Evolution and Infrared Absorption

Abstract
Four a-Si:F:H alloys were prepared in SiF4/SiH4/Ar, SiF4/SiH4/H2, SiF4/H2/Ar and SiF4/H2 mixtures using an inductively-coupled glow discharge technique. A mass spectroscopic analyzer was used to observe gas evolution. In all films, a small amount of SiF4 gas evolved at 120°C, which is lower than the deposition temperature. At 300°C hydrogen evolved, just as has been reported in amorphous hydrogenated film. At 750°C a larger amount of SiF4 gas burst from the film. Infrared transmission results indicate that ≡SiF and =SiF2 in the film change into SiF4 when the film is annealed at a temperature higher than 400°C.