Silicide formation with bilayers of Pd-Pt, Pd-Ni, and Pt-Ni

Evaporated two-layered thin films of Pd-Ni, Pt-Ni, and Pt-Pd on single-crystal Si have been vacuum annealed in the temperature range 200–900 °C. The sequence of films as well as substrate orientation have been varied. The silicide formation has been studied by MeV He+ backscattering spectrometry and glancing angle x-ray diffraction. The silicide layers are highly inhomogeneous in the elemental depth distribution for annealing below 600 °C. Above 700 °C, the distributions become homogeneous. The silicide-substrate interface shows varying sharpness depending upon substrate orientation and evaporation sequence. We suggest the existence of ternary monosilicides of the type Pt1−xPdxSi, Pt1−xNixSi, and Pd1−xNixSi. The Pt1−xPdxSi ternary silicide is stable up to 900 °C; the others are not.