Low-k SiN film for Cu interconnects integration fabricated by ultra low temperature thermal CVD

A new low-k SiN film, with a permittivity of 5.4 and high immunity to Cu diffusion and oxidation, has been successfully developed. A stable SiNCl-like film was obtained at temperatures down to 250/spl deg/C by the thermal CVD method, utilizing hexachlorodisilane (HCD), Si/sub 2/Cl/sub 6/ and ammonia. A practical deposition rate of 1.4 nm/min with good step coverage was achieved at 450/spl deg/C. Despite its low permittivity and low density, HCD-SiN has the same RIE etching resistance as conventional LPCVD SiN, and higher barrier ability for Cu diffusion than plasma-SiN. Using HCD-SiN as the etch-stop and the barrier layer should be the solution to realize Cu damascene interconnects for high performance VLSIs.