Thin-film interdiffusion. I. Au-Pd, Pd-Au, Ti-Pd, Ti-Au, Ti-Pd-Au, and Ti-Au-Pd

Interdiffusion in the Ti/Pd/Au thin-film system is measured using Rutherford backscattering. Interdiffusion rates of Pd/Au for temperatures between 200 and 490 °C have been correlated with the defect structure of the films using models of defect enhanced diffusion. Au diffusing in Pd has been analyzed by the Whipple model of grain-boundary diffusion to give a grain-boundary activation energy of 0.9 eV. Pd diffusing in Au has been analyzed using the grain-boundary-assisted bulk diffusion model and it is shown that dislocation diffusion has to be invoked to explain the amount of Pd in the Au film. Air, as compared with vacuum, annealing enhances interdiffusion in the Ti-Au couple and inhibits interdiffusion in Ti-Pd. Ti-Pd and Ti-Au interdiffusion in the Ti-Pd-Au and Ti-Au-Pd ternary systems is strongly reduced in comparison with interdiffusion in the corresponding Ti-Pd or Ti-Au couples for vacuum annealing.