Blueshift of Fluorinated Amorphous Carbon Films by Fourier Transform Infrared Spectroscopy

The chemical shift of organic materials is one of the important factors in view of the bonding structure, and an amorphous bonding structure in low-dielectric-constant materials is a basic requirement for decreasing the dielectric constant. The chemical shift originates from the conjugated C=C bond and the peculiar phenomenon of the appearance of the terminal C–H bond due to neighboring highly electronegative atoms during the deposition of fluorinated amorphous carbon films. The blueshift due to the condensation of the C–H bond was researched in fluorinated amorphous carbon films, but the redshift due to the elongation of the C–H bond was not observed because the broken C–H bond by fluorine attack becomes an HF bond and evaporates. The breaking of the cross-link structure can be accelerated by annealing and the lowest dielectric constant of the films is 1.98 at the as-deposited film with the cross-link amorphous structure.