Abstract: A process for depositing a dielectric film having a reduced dielectric constant and desirable gap-fill characteristics, at an acceptable deposition rate is disclosed. A filmed deposited according to the present invention possesses acceptable stability, and avoids outgassing of the halogen dopant while resisting shrinkage.A carbon-based dielectric film is deposited on a substrate in a processing chamber by first flowing a process gas into the processing chamber. The process gas includes a gaseous source of carbon (such as methane (CH.sub.4)) and a gaseous source of a halogen (such as a source of fluorine (e.g., C.sub.4 F.sub.8)). A plasma is then formed from the process gas by applying a first and a second RF power component. Preferably, the second RF component has a frequency of between about 200 kHz and 2 MHz and a power level of between about 5 W and 75 W. The first and a second RF power components are applied for a period of time to deposit a halogen-doped carbon-based layer.