The interaction of metals and barrier layers with fluorinated silicon oxides

Fluorinated silicon oxide (FSG) films with varying fluorine (F) content were prepared by plasma-enhanced chemical vapor deposition (PECVD) using TEOS, O 2, and either C 2F 6 or NF 3. Metal films (Al, Cu–1% Al, Cu) were deposited on the FSG either directly or with a barrier layer (Ta, TaN) between the metal and the FSG. In addition, undoped PECVD SiO 2 was studied as a capping layer on the FSG. Compositional depth profiles were obtained with both XPS and nuclear reaction analysis (NRA). F diffused rapidly through Ta, TaN and Al, and reacted with Al on the top surface. On the other hand, regardless of barrier layers, Cu showed almost no reaction with F. F diffusion was also observed through PECVD SiO 2.