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, Pt 1-xNixSi, and Pd1-xNixSi. The Pt1-xPdxSi ternary silicide is stable up to 900°C; the others are not.