ON THE NANOMETER-SCALE SOLID-STATE REACTIONS AT THIN-FILM NI AMORPHOUS SIC AND CO AMORPHOUS SIC INTERFACES

Solid-state interfacial reactions between self-supporting thin (50, 100, and 200 angstrom) films of Ni and Co, and amorphous (a) films of SiC, Si and C were investigated in the 300-1000-degrees-C temperature range. The metastable solubility of C (from SiC) in Ni and Co after short annealings was calculated from the metal lattice expansion after accounting for the effect of Si. A maximum of approximately 7 at. % C dissolves in (Ni) at approximately 300-degrees-C, a value close to the maximum solubility of C in rapidly quenched Ni-C alloys. In contrast, a lack of change in the Co lattice parameter after reactions with either SiC, Si, or C indicates negligible dissolution of C prior to silicide nucleation. The first silicides in metal/a-SiC reactions (Ni31Si12, and Co2Si) are more metal-rich than in metal/a-Si reactions.