Thin-film interdiffusion. II. Ti-Rh, Ti-Pt, Ti-Rh-Au, and Ti-Au-Rh

Interdiffusion in the Ti/Rh/Au and Ti/Pt thin-film systems is measured using Rutherford backscattering. Extensive grain size measurements are used to interpret the data in terms of grain-boundary-assisted bulk diffusion. At room temperature, rapid grain-boundary diffusion of Au into the fine-grained Rh layer of the Ti-Rh-Au films occurs, characterized by a diffusion coefficient DB∼10−16 cm2/sec. The bulk diffusion of Au into the grains of the Rh film layer is examined using the grain-boundary-assisted bulk diffusion model, and the influence of surface segregation and size effects is discussed. It is found that interdiffusion in Ti-Rh and Ti-Pt couples is much slower than in Ti-Pd or Ti-Au. Methods are suggested by which the utility of Ti-Rh-Au as a conductor metallization might be improved.