Phase formation and thermal stability of periodic Ni-silicide nanocontact arrays on epitaxial Si _1-x C _x layers on Si(1 0 0)

We report here on the first study of the interfacial reactions of nanoscale Ni metal dots on single-crystal Si _1-x C _x (1 0 0) substrates at various heat treatments. The formation of high-resistivity NiSi ₂ phase was found to be more favorable for the miniature size Ni nanodots. The incorporation of C to Si substrates exhibited significant beneficial effects on improving the thermal stability of low-resistivity NiSi nanocontacts. The process window of low-resistivity NiSi in the Ni nanodots/Si _1-x C _x (1 0 0) sample was greatly extended by 200-250°C as compared to that in the Ni nanodots/Si(1 0 0) sample. The presence of C atoms is thought to lower the NiSi nanocontact/Si _1-x C _x interface energy and/or to block the Ni diffusion paths during high temperature annealing. For the Ni nanodots/Si _1-x C _x (1 0 0) sample annealed at 900°C, highly curled and tangled amorphous SiO _x nanowires with diameters of 8-20 nm were found to form. The growth process of these amorphous SiO _x nanowires could be explained by the solid-liquid-solid (SLS) mechanism.