Molybdenum thin films of about 200nm thick and deposited onto Si (100) wafers were processed in pure N2, (Ar–35%N2) and (Ar–25%N2–30%H2) expanding microwave plasma at 673K. Secondary neutral mass spectrometry and Raman spectroscopy were used to make correlations between the composition and the structure of the as-formed compounds. The low nitrogen diffusion up to a depth of about 40nm was correlated to the formation of well crystallized MoO2 of monoclinic structure acting as a barrier of diffusion for nitrogen, in molybdenum films exposed to pure N2 and (Ar–35%N2) plasma. The large nitrogen diffusion into the film exposed to ternary (Ar–25%N2–30%H2) plasma was correlated to the reduction of MoO2 oxides by hydrogen species such as atomic hydrogen, NHx<3… contained in ternary plasma. The formation of Mo–N phases with defects could take place in molybdenum films processed at 673K compared to the results obtained at 873K.

Expanding Microwave Plasma Process for Thin Molybdenum Films Nitriding: Nitrogen Diffusion and Structure Investigations. I.Jauberteau, T.Merle-Méjean, S.Touimi, S.Weber, A.Bessaudou, A.Passelergue, J.L.Jauberteau, J.Aubreton: Surface and Coatings Technology, 2011, 205[2], S271-4