Amorphous TiO2 in LP-OMCVD TiNxOy thin films revealed by XPS

TiN(O)-TiO2 thin films were prepared on Si(1 0 O) by the low pressure organo metallic chemical vapor deposition (LPOMCVD) method, using ammonia and titanium isopropoxide as precursors. In order to complete previous characterizations, an Ar+ bombardment/XPS coupled study was carried out. This method is based on the fact that the behavior of a compound towards an ion bombardment is a function of its composition. In particular, Ar+ bombardment of TiO2 (whatever its form) leads to a preferential sputtering of oxygen atoms with subsequent reduction of titanium and formation of Ti3+ and Ti2+ easily detectable by XPS from a significant broadening of the Ti 2p lines. In the opposite, no broadening of the Ti 2p lines is observed for an Arf bombardment of TiN. Then, with this method, we succeed in showing that films obtained at high temperature (greater than or equal to 700 degreesC) contain only a TiNxOy phase which is isomorphic to TiN. In the coatings, synthesized at low temperatures (less than or equal to 650 degreesC) amorphous TiO2 has been evidenced. (C) 2001 Elsevier Science B.V. All rights reserved.