Diffusion in thin bilayer films during rapid thermal annealing

The knowledge of pre-exponential factors and activation energies for low temperatures and short annealing times in nanoscaled systems is important for the downscaling of thermal processes. Here, the diffusion coefficients in aluminum-nickel, aluminum-titanium, titanium-silicon, and aluminum-copper bilayers were determined using rapid thermal annealing. The annealing time was set to 500 s and the investigated bilayer thin film thicknesses were 2 μm. The temperatures ranged from 389 to 613 K depending on the bilayer system. For the various material combinations, the diffusion coefficients were determined by elemental depth profiling and compared to literature values. For the aluminum-copper system, a good agreement with literature and a single set of values was found, whereas for aluminum-nickel, aluminum-titanium, and titanium-silicon two or more sets of values were observed.