Phase formation and thermal stability of periodic Ni-silicide nanocontact arrays on epitaxial Si1−xCx 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 Si1−xCx(1 0 0) substrates at various heat treatments. The formation of high-resistivity NiSi2 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/Si1−xCx(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/Si1−xCx interface energy and/or to block the Ni diffusion paths during high temperature annealing. For the Ni nanodots/Si1−xCx(1 0 0) sample annealed at 900 °C, highly curled and tangled amorphous SiOx nanowires with diameters of 8–20 nm were found to form. The growth process of these amorphous SiOx nanowires could be explained by the solid–liquid–solid (SLS) mechanism.