Phase diagrams and metal-rich silicide formation

Phase formation at temperatures well below the melting point of the phases was studied in thin silicon–near-noble-metal films by means of 4He+ ion-backscattering spectrometry and x-ray diffractometry in SiO2/Si/M film systems, where the metal-film thickness was larger than that of the Si film. In the initial stage of compound formation where both unreacted Si and M layers are present, the M2Si phase has been found. At increasing annealing times and temperatures, more and more metal-rich phases have been detected. The Si-Ni thin-film system evolution follows exactly the phase diagram reported in the literature; moreover, for Ni, Pt, and Pd-Si thin-film interactions the end phases are dictated by the phase equilibrium and can be predicted by the phase diagrams.