Preparation of amorphous fluorinated carbon film using low global-warming potential gas, C4F6, by plasma enhanced chemical vapor deposition

Low-dielectric constant amorphous fluorinated carbon (a-C:F) films were prepared using plasma enhanced chemical vapor deposition (PECVD) from C4F6 gas, which is expected to be a substitutional gas due to its low global-warming potential (GWP). Kinetic analysis revealed that C4F6 (hexafluoro-1,3-butadiene) or related molecules were a main deposition precursor and that C4F6 concentration in the plasma affected the C-CF bond ratio in the film. The contribution of orientational polarization to total dielectric constant was related to the C-CF bond ratio. The change in dielectric constant induced by changing residence time in the reactor or by changing Ar dilution of C4F6 gas was due mostly to the change in orientational polarization. Controlling the C4F6 concentration in the plasma by changing residence time is the key to controlling orientational polarization and dielectric constant.