Interdiffusion in Au(120 nm)/Ni(70 nm) thin films at the low-temperature annealing in the different atmospheres

The development of the interdiffusion processes and the surface morphology changes in thin films of Au(120 nm)/Ni(70 nm) during annealing at 200 °C for 20 min in vacuum with different residual atmosphere pressures of 10−3 and 10−6 Pa and in an environment of hydrogen at a pressure of 5 × 102 Pa have been studied. Secondary ion mass spectrometry, Auger electron spectroscopy, X-ray diffraction, optical microscopy, atomic force microscopy and scanning electron microscopy were used. Surface microdefects that form in the films are related to the local oxidation of nickel and to the stress that arises due to interdiffusion. Defect formation and reactions at the surface are found to be controlling factors in the transport of nickel to the surface and in the observed morphology. ► The atmosphere alters diffusion rates of Ni in an Au layer at 200 °C. ► Local defects with higher Ni concentration occur after annealing in vacuum 10−3 Pa. ► Hydrogen atmospheres or vacuum of 10−6 Pa provide smooth surfaces after annealing. ► Defects arise from local oxidation and the stress caused by interdiffusion.