The room temperature oxidation process of thin TiNx films, grown by DC reac
tive magnetron sputtering, was studied by in-situ and real time spectroscop
ic ellipsometry, X-ray reflectivity, Auger electron spectroscopy, X-ray pho
toelectron spectroscopy and stress measurements. The films were deposited a
t various negative bias voltages (V-b) in order to vary the TiNx stoichiome
try and then exposed to several gases and to air at room temperature. The o
xidation rate was found to depend strongly on V-b and thus on film stoichio
metry. Fast oxidation was observed in films deposited at low \V-b\, that co
ntain nitrogen which is weakly bonded to Ti and can be easily replaced by o
xygen. At high \V-b\ values (aboue - 80 V) stoichiometric TiN films were de
veloped, that were stable and not prone to oxidation. The results showed th
at oxidation takes place in the bulk of thr: film and can proceed up to abo
ut 10% transformation of titanium nitride into titanium oxide. The fastest
step in the him oxidation mechanism is diffusion of oxygen along the column
ar grain boundary structure, followed by the reaction of oxygen with the we
akly bonded TiN. The results suggest that the oxidation process proceeds wi
th different stages involving formation of TiON, followed by a slow stage o
f TiO2 formation. These microstructural changes are consistent with the evo
lution of compressive stresses in the films surd the increase in film densi
ty and thickness and the: decrease in surface roughness as determined by X-
ray reflectivity. (C) 1999 Elsevier Science S.A. All rights reserved.