Fluorinated amorphous carbon thin films grown from C ₄F ₈ for multilevel interconnections of integrated circuits

Fluorinated amorphous carbon thin films (a-C:F) for use as low-dielectric-constant (low-k) interlayer dielectrics were deposited by helicon-wave Plasma-Enhanced Chemical Vapor Deposition (PECVD) using fluorocarbon compounds as a source material. The a-C:F films could be grown from C ₄F _S at a high deposition rate (above 400 nm/min) and they were thermally stable up to 300°C. The addition of bias power to the substrate made it possible to completely fill gaps in the wiring (space 0.35 μm. height 0.65 μm) with the a-C:F film. To protect the a-C:F film during further processing, we deposited an SiO ₂ film to add mechanical strength and resistance to the oxygen plasma used to remove resist materials. The adhesG-Cion between the a-C:F and SiO ₂ films was dramatically improved by inserting an adhesion promoter consisting of a-C:H and Si-rich SiO ₂.