A nitride film for diffusion barrier applications was prepared via the nitridation of a fine-grained chemical vapor deposited W film. The latter was deposited at

300C in a low-pressure chemical vapor deposition reactor, under a total gas pressure of 0.1Torr. Subsequent nitridation was carried out in N plasma at 300C. The thickness of the nitride layer, as examined by means of secondary ion mass spectroscopy, was 50nm after 300s exposure to N plasma. The X-ray photoelectron spectroscopic spectra showed that the atomic ratio of W to N in the nitride layer was 2:1. According to Auger electron spectroscopic data, and measurements of n+p junction leakage currents, Al/WNx/W/Si multi-layers maintained excellent interfacial stability during furnace annealing (575C, 0.5h). The effectiveness of the W2N barrier was attributed to the stuffing of grain boundaries with N atoms. This eliminated rapid diffusion paths from fine-grained chemical vapor deposited W films.

Nitridation of Fine Grain Chemical Vapor Deposited Tungsten Film as Diffusion Barrier for Aluminum Metallization. K.M.Chang, T.H.Yeh, I.C.Deng: Journal of Applied Physics, 1997, 81[8], 3670-6