Formation and characteristics of fluorinated amorphous carbon films deposited by CF4/CH4 ICPCVD

Fluorinated amorphous carbon thin films were deposited on a p-type Si(100) substrate using a mixture of carbon tetrafluoride (CF4) and methane (CH4) gases and an inductively coupled plasma chemical vapor deposition (ICPCVD). Fourier transform infrared and X-ray photoelectron spectroscopy spectra show that the film has C-F, C-F2, C-F3, C-Fx, and C-C bonds. Also, the dielectric constant may be decreased greatly due to the C-F bond in the film. It is found that the C-Fx bonding configuration changes from a C-F bond to C-CFx and C-F3 bonds as a function of the CF4/CH4 flow rate ratio. Therefore, a reduction of the dielectric constant can be obtained by varying the C-CFx bonding configuration as well as by incorporating fluorine. The relative dielectric constant, the leakage current density, and the dielectric breakdown field of as-deposited film with a CF4/CH4 flow rate ratio of 7 at a 200mTorr working pressure and an 800W rf power are about 2.4, 7 x 10-12 A/cm2, and above 15 MV/cm, respectively