The invention concerns a method for applying a surface modification agent composition for organosilicate glass dielectric films. More particularly, the invention pertains to a method for treating a silicate or organosilicate dielectric film on a substrate, which film either comprises silanol moieties or has had at least some previously present carbon containing moieties removed therefrom. The treatment adds carbon containing moieties to the film and/or seals surface pores of the film, when the film is porous.