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 organ o metallic chemical vapor deposition (LPOMCVD) method, using ammonia and ti tanium isopropoxide as precursors. In order to complete previous characteri zations, 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 bombard ment is a function of its composition. In particular, Ar+ bombardment of Ti O2 (whatever its form) leads to a preferential sputtering of oxygen atoms w ith 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 bombardme nt of TiN. Then, with this method, we succeed in showing that films obtaine d 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 be en evidenced. (C) 2001 Elsevier Science B.V. All rights reserved.