Crystallization of Reactively Sputtered Amorphous Tungsten Nitride Film

An amorphous tungsten nitride film with a 10–40 at.% nitrogen concentration was produced by reactive sputtering. The amorphous W 67 N 33 film could be fully crystallized into a pure α-tungsten phase with equaixed grains, which had a similar resistivity to that of the sputtered pure tungsten film, by rapid thermal annealing (RTA) for 60 s at 1273 K. It was also found that the nitrogen content in the tungsten nitride films decreased significantly. This decomposition of tungsten nitride at least restrained the formation of interface reaction products such as tungsten silicide without an additional diffusion barrier layer. The RTA process of the amorphous tungsten nitrides showed the possibility of the formation of the low-resistivity pure tungsten film without a diffusion barrier.