Fluorinated amorphous carbon films (α-F:C) were deposited by high-density plasma-chemical vapor deposition (HDP-CVD) using C4F8 and CH4 as precursors. The deposition process was performed at two temperatures: ∼200 and ∼350°C. In order to study the thermal stability of the films, the samples were annealed at 400 or 500°C for 30min in an N2 ambience. We have found that the films deposited at ∼350°C were more thermally stable than those deposited at ∼200°C. Both deposition conditions produced α-F:C films with a C:F ratio of 1.7 and a very low content of H; The bonding types identified by XPS were C-C/C-H, C-CF, CF-CF and C-F in all the α-F:C films and in addition CF2 bond was found in the as-deposited films deposited at ∼200°C. The films' composition was maintained after annealing at 400°C. However, after 500°C annealing, in the low-temperature deposited films, F out-diffusion was observed in large amounts compared to the very small changes observed in the high-temperature films. The α-F:C films remained amorphous at least up to 500°C. The dielectric constant of the low-temperature deposited films was ∼2.7 after 400°C annealing, and increased after 500°C anneal to ∼9.3. The high-temperature deposited films had a higher dielectric constant of ∼2.7-3, remaining stable after the various thermal treatments employed. These results indicate a trade-off between thermal stability and lowering the dielectric constant.