Plasma deposited CF polymer films as ultra low k intermetal dielectric, film properties and application

The ongoing process of miniaturization in ULSI device fabrication has reached its limit. The reduction of cross talk and signal delay time of interconnects requires the application of low permittivity (low k: k <3.9, ultra low k: k<2.2) dielectrics in sub 0.18 /spl mu/m technologies. New materials (low k dielectrics with k/spl les/2.7 in combination with copper) must replace the usually applied SiO/sub 2/ (k/spl ap/3.9) dielectric. Among all new low k materials, amorphous carbon fluoride (CF) polymers deposited by plasma enhanced chemical vapor deposition (PE CVD) are one of the more promising CVD materials with stable 2.3 k. CF polymer films were deposited on silicon and different barrier and etch stop layers. Adhesion failures could be avoided by in situ deposition of a very thin (10 nm) adhesion layer. The influence of the additional film on dielectric film properties (dielectric constant: 2.0/spl les/k/spl les/2.3, break down field strength: Ebd>5 MV/cm, leakage current density @ /spl plusmn/5 V: <4/spl times/10-11 A/cm2) is negligible. After thermal treatment (T/spl les/400/spl deg/C) in vacuum or in nitrogen atmosphere hardly any changes in electrical and optical properties and in surface topology could be detected. Patterning by chemical mechanical polishing (CMP) and reactive ion etching (RIE) was tested successfully and will be applied in single damascene architecture.