Diffusion formation of nickel silicide contacts in SiNWs

Time and temperature dependencies of nickel silicide axial growth in Si nanowires (SiNWs) were studied for a temperature range of 300–440 °C and nanowire diameters of 30–60 nm. A square root time dependence of the total silicide intrusion length was found. It was concluded that formation of nickel silicides was controlled by diffusion of Ni along the nickel silicide surface or the nickel silicide/SiO2 interface to the Si/silicide interface. Subsequent annealing cycles at different temperatures revealed Arrhenius-type behavior for the increase of the intrusion length square (ΔLn2) with an activation energy of 1.45 ± 0.11 eV. Additional and significant silicide growth during heating and cooling of the wire was taken into account by using self consistent iteration procedure for ΔLn2 calculations. The resulted activation energy agrees well with previous results.

► Two silicide phases formed in the SiNW during RTA at 350–440 °C: NiSi and Ni1+xSi (x > 0).
► A square root time dependence of the intrusion length was found for SiNWs investigated.
► Activation energy of the nickel silicide growth, 1.45 ± 0.11 eV, was found.
► The heating and cooling were taken into account in the activation energy evaluation.
► Nickel silicide formation in SiNWs is controlled by interface diffusion of Ni.