Effects of deposition method on the microstructure and intermetallic compound formation in Ag-Sn bilayers

Thermal evaporation and magnetron sputtering were used for the deposition of bilayers of Ag and Sn with different stacking sequences of the sublayers, Ag on Sn (Ag/Sn) or Sn on Ag (Sn/Ag). The deposition method used significantly affects the intermetallic compound (IMC) formation in these thin films already during film deposition. Comparison of the corresponding microstructures and textures indicates that the observed, striking differences in IMC formation for the case of Ag/Sn bilayers can be related to the interplay of Sn upward diffusion, surface energy and interfacial intermixing for the two deposition methods.