In-situ study of the dewetting behavior of Au/Ni bilayer films supported by a SiO2/Si substrate

Solid state dewetting of Au/Ni bilayer films was investigated by in-situ cross-sectional TEM heating with energy-dispersive X-ray spectroscopy. The early stage of dewetting process revealed both grain boundary grooving at the surface of the Ni layer and void nucleation along the Au/Ni interface between Au grains. During annealing, inter-diffusion occurred and enhanced solubility was found between Au and Ni. Au diffused predominantly through Ni grain boundaries and decorated the Ni/substrate interface. The energetically preferred adsorption of Au at the Ni/SiO2 interface and at Ni grain boundaries, coupled with some alloying in the volume of the metal films delays the break-up of the bilayer film compared to pure Au or Ni films. The experimental observations confirm that dewetting kinetics of metal bilayer films are strongly affected by both partial alloying of the metals as well as the metal/metal interface.

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