The bond structure and dielectric properties of fluorinated carbon films after thermal annealing in N-2, ambience were studied. The results show that dielectric constant and dielectric loss increased, and optical gap decreased with increasing annealing temperature. The composition and bonding structure of the films were obtained by FTIR and XPS analysis. The data indicate that fluorine-to carbon ratio decreased and C=C group increased in the films after the films were annealed. It suggests that the structural and dielectric property changes correlate with the release of fluorine and increase of cross-linking during the annealing. (C) 2002 Elsevier Science B.V. All rights reserved.