Effect of fluorine on moisture absorption and dielectric properties of SiOF films

Abstract

The effect of fluorine on moisture absorption and dielectric properties of SiOF films as a function of SiF 4/O 2 gas flow ratio was investigated The films were deposited by using ECR plasma CVD with various gas flow ratios (SiF 4/O 2 = 0.2 ~ 1.6) diluted in Ar. Characterization of films was carried out accordingly in terms of the gas flow ratios. The chemical bonding structure of the films was evaluated by Fourier transform infrared spectroscopy (FTIR), fluorine concentration by X-ray photoelectron spectroscopy and refractive index by ellipsometry. The dielectric characteristics were determined from C-V measurements at 1 MHz. Fluorine concentration increases gradually from 5.0 to 14.5 at.% with the SiF 4/O 2 flow ratio in the range from 0.2 to 1.6. In FTIR spectra, the > Si-F 2 bond peak was observed to rise when the SiF 4/O 2 gas flow ratio was larger than 1.0. The FTIR spectra in the high wavenumber region shows that Si-OH bond increased with increasing Si-F bond intensity. The dielectric constant of the SiOF films was changed from 3.15 to 4.06 after the boiling treatment in boiling water for . 100 min.