The properties of W–Ge–N thin films were reported, focusing on issues relevant to their use as diffusion barriers for Cu metallization on silicon. The amorphous W–Ge–N thin films were deposited on thermally grown SiO2/Si using reactive sputter deposition. This was followed by in situ deposition of Cu films. Annealing studies for W–Ge–N were then carried out in a vacuum to investigate Cu diffusion and barrier film crystallization. X-ray diffraction was used to assess the crystallinity of the films upon annealing. The results show that W–Ge–N has a recrystallization temperature that was higher that that for WNx. Auger electron spectroscopy was used to measure the depth profile of Cu diffusion through the barrier layer. Little or no Cu diffusion was detected for a relatively high annealing temperature. The W–Ge–N films were conductive, although the resistivity was somewhat higher than that for WNx. The results suggested that W–Ge–N may be an attractive diffusion barrier material for Si or SiGe devices.

Properties of W–Ge–N as a Diffusion Barrier Material for Cu. S.Rawal, D.P.Norton, T.J.Anderson, L.McElwee-White: Applied Physics Letters, 2005, 87[11], 111902 (3pp)