Effect of fluorine on dielectric properties of SiOF films

The effect of fluorine addition on silicon oxide film properties as a function of SiF4/O-2 gas flow ratio was investigated. The films were deposited by using electron cyclotron resonance plasma chemical vapor deposition with SiF4 and O-2 as source gases diluted in Ar. Characterization of films was carried out in terms of various gas flow ratios (SiF4/O-2=0.2-1.0). The microwave power and substrate temperature during deposition were fixed at 700 W and 300 degrees C, respectively. The chemical bonding structure of the films was evaluated by Fourier transform infrared spectroscopy (FTLR), fluorine concentration by x-ray photoelectron spectroscopy, and refractive index by ellipsometry. The dielectric constant was determined from C-V measurements at 1 MHz. FTIR spectra show that as the fluorine concentration increased, the intensities of the Si-F bonding peak and the shoulder peak (at around 1160 cm(-1)) of the Si-O stretching mode both increased. Refractive index and deposited film density decreased with increasing SiF4/O-2 gas flow ratio. The SiOF film deposited at a SiF4/O-2 gas flow ratio of 1.0 exhibited a fluorine content of 11.8 at. % and a dielectric constant of 3.14. (C) 1996 American Institute of Physics.