Growth of Co-Silicides from single crystal and evaporated Si

We have investigated the reaction of a thin Co film with a (100) Si (Si^c) or an evaporated Si (Si^e, which is amorphous) substrate during thermal annealing. On either substrate, Co₂Si and CoSi form simultaneously and the growth of each phase has a square root of time dependence. Both silicides grow faster on Si^c than on Si^e. A model is proposed to calculate the effective diffusion constant in each silicide from the growth data of the silicides. The activation energies of the effective diffusion constants in Co₂Si and CoSi grown on Si^c are 1.7±0.1 eV and 1.8±0.1 eV, respectively; while those on Si^e are 1.85±0.1 eV and 1.9 ±0.1 eV, respectively. The differences observed for the two substrates are tentatively attributed to the presence of impurities in Si^e and to the microstructural differences of the silicides formed on either substrate.