When a Ta layer is deposited at the Si-Ti interface a new phase has been detected, i.e., the TiSi2, C40. The C40-C54 transformation kinetics and the film morphology are consistent with an increase of the nucleation density with respect to the C49-C54 transition, The activation energies for the nucleation rate (4.2 +/- 0.3 eV) and the growth velocity (4.0 +/- 0.4 eV) have been obtained from the in situ sheet resistance and the transmission electron microscopy results. These results show that the process with a Ta layer at the Ti-Si interface has a greater scalability with respect to the standard TiSi2, process. (C) 2002 Elsevier Science B.V. All rights reserved.