Fluorine-doped silicon dioxide (SiOF) films have been found to exhibit a low dielectric constant. However, the critical issue about SiOF is its low resistance to moisture absorption that causes the dielectric constant of the film to increase with time. In this work, the effects of the post plasma treatment on the dielectric stability of SiOF thin films was investigated. It has been observed that O-2 plasma treatment of SiOF is quite efficient at blocking moisture. The dielectric constant of SiOF films after post O-2 plasma treatment is very stable. However, the dielectric constant of SiOF films after the plasma treatment increased from 3.14 to 3.43 due to fluorine desorption from the SiOF film and densification due to O-2(+) ion bombardment effect. Nevertheless, the dielectric constant of SiOF films which had no plasma treatment after boiling treatment increased from 3.14 to 3.64, while that of the plasma-treated film with radio frequency bias power of 150 W increased from 3.43 to 3.47, which corresponds to about 15 and 1.2% increments, respectively. Also, the breakdown field strength of SiOF films after O-2 post plasma treatment increased from 3.5 to 8 MV/cm. Therefore, both surface oxidation and densification resulting from O-2 plasma treatment seemed to play a major role in making the SiOF film an attractive material for ultralarge-scale integrated intermetal dielectrics.