FTIR characterization of fluorine doped silicon dioxide this films deposited by plasma enhanced chemical vapor deposition

Fluorine doped silicon dioxide (SiOF) thin films have been prepared by plas ma enhanced chemical vapor deposition. the Fourier transform infrared spect rometry (FTIR) spectra of SiO2 films are deliberated to reveal the structur e change of SiO2 and the mechanism of dielectric constant reduction after d oping fluorine. When F is doped in SiO2 films, the Si-O stretching absorpti on peak will have a blue-shift due to increase of the partial charge of the O atom. The FTIR spectra indicate that some Si-OH components in the thin f ilm can be removed after doping fluorine. These changes reduce the ionic an d orientational polarization, and result in the reduction in dielectric con stant of the film. According to Gaussian fitting, it is found that the Si-F -2 bonds will appear in the SiOF film with increase of the fluorine content . The Si-F-2 structures are liable to react with water, and cause the same increase of absorbed moisture in the film.