The moisture absorption in fluorinated silicon oxide (SiOF) film was reduced by adding Ar during film deposition, thus the stability of the film was improved. The film was prepared by parallel plate plasma enhanced chemical vapor deposition by adding Ar into the deposition process of SiOF film using Si2H6, N2O, and CF4. The result of Fourier transform infrared spectroscopy showed that the Si-F peak intensity increased with Ar added; meanwhile, the relative Si-OH peak intensity decreased indicating less moisture absorption. As the result, the dielectric constant and leakage current of the SIOF film with Ar decreased compared with those of the SIOF film without Ar.