A stable fluorosilicate glass (FSG) has been fabricated from the chemical vapor deposition of SiF4/tetraethylorthosilicate (TEOS)/O-2 and C2F6/EOS/O-2. Films were subjected to a temperature and humidity stress for water absorption studies and were thermally stressed for fluorine diffusion studies. Fourier transform infrared spectrometry (FTIR) and secondary ion mass spectrometry (SIMS) indicate films produced from SIF4 absorb less water acid diffuse less fluorine into SiOx than films produced from C2F6. The activation energies of fluorine diffusion were calculated to be 1.00 and 0.82 eV for SiF4 and C2F6 FSG, respectively.