A comprehensive review on interfacial reactions to form silicides between metal and Si nanowire or wafer is given. Formation of silicide contacts on Si wafers or Si nanowires is a building block needed in making current-based Si devices. Thus, the microstructure control of silicide formation on the basis of kinetics of nucleation and growth has relevant applications in microelectronic technology. Repeating events of homogeneous nucleation of epitaxial silicides of Ni and Co on Si in atomic layer reaction is presented. The chemical effort on intrinsic diffusivities in diffusion-controlled layer-typed intermetallic compound growth of Ni2Si is analyzed.