Abstract: Ion implantation of fluorine into SiO.sub.2 films results in formation of a dielectric material having a dielectric constant K.ltoreq.3.2. High energies associated with ion implantation permit stable introduction of high concentrations of fluorine within silicon oxide, without giving rise to problems of fluorine outgassing and water absorption associated with conventional FSG deposition techniques. Relatively thick FSG layers conventionally formed by CVD may be sandwiched between implanted FSG liner films formed in accordance with the present invention. Such a combination would reduce the dielectric constant of the dielectric structure as a whole while providing a barrier to fluorine diffusion, without consuming the processing time required to implant an entire dielectric layer.