Silicide islands formation and diffusion processes during solid-state reaction of metallic glasses thin films with single crystalline silicon substrates

The formation of silicide islands during solid state reactions of thin films of Pd-W, Pd-Ta and Ni-Nb metallic glasses with Si substrates was studied by TEM. Pd2Si or NiSi2 islands were found to grow epitaxially in Si as a result of Pd or Ni diffusion from the films. The crystallization of films results in the rapid increase of their diffusion inside the substrate. It leads to an increase of Pd2Si islands thicknesses which previously grew parallel to the film/Si interface. Some islands (''negative'') were observed to dissolve with time showing the change of the reaction direction. This fact is explained by the possible change of the sign of the Gibbs energy variation Delta G during interface reactions of amorphous metallic films with Si. Some ''negative'' Pd2Si islands were observed to move during reactions forming channels parallel to films/Si interfaces. Diffusion processes during the film crystallization were studied by TEM. It allows us to estimate the diffusion parameters of Pd in amorphous Pd-Ta film. The complex structure of the partially crystallized film has been found.