Fluorinated amorphous carbon thin films grown from C₄F₈ for multilevel interconnections of integrated circuits

Fluorinated amorphous carbon thin films (a-C:F) for use as low-dielectric-constant interlayer dielectrics were deposited by helicon-wave plasma-enhanced chemical vapor deposition using fluorocarbon compounds as a source material. The a-C:F films could be grown from C₄F₈ 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 a SiO₂ film to add mechanical strength and resistance to the oxygen plasma used to remove resist materials. The adhesion between the a-C:F and SiO₂ films was dramatically improved by inserting an adhesion promoter consisting of a-C:H and Si-rich SiO₂.