Fluorocarbon films with low dielectric constants and high thermal resistance have been developed by plasma-enhanced chemical vapor deposition (PECVD) using gas mixtures of fluorocarbons (e.g., C4F8), hydrocarbons (e.g., C2H2), and/or hydrogen. A conventional parallel plate electrode PECVD system was used as the reactor. We report dielectric constants lower than 2.4 with these fluorinated films. The thermal of composition temperature was higher than 400 degrees C and the glass transition temperature (Tg) was also higher than 450 degrees C. This enables the use of organic films with very low dielectric constant in actual devices.