Lateral diffusion of Ni and Si through Ni2Si in Ni/Si couples

Abstract

Lateral diffusion couples of Ni on Si layers and Si on Ni layers were used in conjunction with scanning electron microprobe measurements to investigate the growth of Ni silicides in the temperature range 400–700 °C. The phase Ni2Si grows proportional to (time)1/2 until a length of 25–30 μm (at 600 °C) where the phase sequence Ni5Si2, Ni2Si, Ni3Si2, and NiSi is observed. Both Ni and Si diffuse through Ni2Si with an effective diffusion coefficient D≃0.02 cm2/s ×exp[−(1.4±0.1) eV/kT]. The diffusion of Si was also observed by the growth of Ni2Si in Ni films at the periphery of contact openings in SiO2 layers on Si.