Silicidation of Co/Si Core Shell Nanowires

Abstract

Theformation of CoSi2 nanowires (NWs) via the annealing of SiNWs conformally coated with atomic layer deposited (ALD) Co layerswas investigated. Co ALD was carried out using Co(iPr-AMD)2 andNH3 as a precursor and a reactant, respectively. Rapid thermalannealing (RTA) of Co/Si core-shell NWs produced Co oxide insteadof CoSi2 due to oxygen contamination during annealing. To preventoxygen contamination, a highly conformal ALD Ru layer was usedas a capping layer. X-ray diffraction showed the formation ofCoSi2 when the Co/Si core-shell NWs were annealed at over800°C. To investigate the deposition and silicidation process on ananometer scale, high resolution Cs-corrected scanning transmission electron microscopy wasutilized with electron energy loss spectroscopy and energy dispersion spectroscopy.In contrast to previous reports on silicidation of NWs, thedominant diffusion species was found to be Si instead ofCo based on a nucleation-controlled reaction. ©2012 The Electrochemical Society