C‐F materials, deposited by chemical vapor deposition (CVD) have been studied for their potential use as a low dielectric constant intermetal dielectric material for semiconductor applications. Though a dielectric constant of ∼2.4 has been determined, thermal stability of the material needs to be improved. It is shown that the presence of O and/or OH in the system causes a pyrolytic decomposition of the material causing CO and CO2 to outgas from the material at low temperatures. This causes the C‐F matrix to disintegrate and release CFx ions. Minimizing the O/OH content in the films improves thermal stability. Various structural properties of the films have been investigated using X‐ray photoelectron spectroscopy and nuclear magnetic resonance spectroscopies. © 1999 The Electrochemical Society. All rights reserved.