Application of Fluorinated Amorphous Carbon Thin Films for Low Dielectric Constant Interlayer Dielectrics

Abstract

Fluorinated amorphous carbon thin films ( a -C:F) for use as low-dielectric-constant interlayer dielectrics are deposited by helicon-wave plasma-enhanced chemical vapor deposition using fluorocarbon compounds as a source material. The a -C:F films can be grown from C 4 F 8 at a high deposition rate (above 400 nm/min) and they are thermally stable up to 350°C. The addition of bias power to the substrate makes 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, a SiO 2 film is deposited to add mechanical strength and resistance to the oxygen plasma used to remove resist materials. The adhesion between the a -C:F and SiO 2 films is dramatically improved by inserting an adhesion promoter consisting of a -C:H and Si-rich SiO 2 . By using the a -C:F and SiO 2 dielectrics and chemical mechanical polishing (CMP) process, globally planarized 3-level metallization is achieved. The a -C:F dielectric can reduce inter-line capacitance close to a half value as compared with the conventional SiO 2 dielectrics.