In situ investigations of the metal/silicon reaction in Ti/Si thin films capped with TiN: Volumetric analysis of the C49-C54 transformation

The thermal expansion coefficients associated with the C49 and C54 crystal directions have been determined by in situ x-ray diffraction analysis of Ti film annealing deposited on Si substrates. Evidence of a clear anisotropy in the C49 coefficients has been obtained: the alpha (b) is considerably smaller than alpha (a) and alpha (c). The volume expansion is larger in C54: this contributes to reduce to 1.6% at the transformation temperature, the observed 2.0% volume difference at 300 K. The magnitude of the volume discontinuity during transformation is an indication for a first-order transition.