The effects of nitrous oxide plasma surface treatment of fluorinated silica glass (FSG) films were investigated to improve film stability and adhesion properties. FSG films with varying fluorine concentrations were deposited using plasma-enhanced chemical vapor deposition (PECVD), then exposed to a nitrous oxide plasma to modify the surface. Treated films were boiled to study the moisture absorption, and subsequent depositions of foreign passivation films such as silicon nitride, silicon oxynitride, etc., were used to study the changes in adhesion characteristics. It was found that plasma treatments under certain conditions could enhance the adhesion characteristics of films with higher fluorine dopant levels, but did not measurably change the moisture resistance of the films. The effects of the plasma treatment were confined to the surface and did not measurably effect the bulk properties of the film. The effects of the nitrous oxide plasma treatment of PECVD FSG films are presented along with proposed mechanisms to explain the effects.