Surface Diffusion Controlled Formation of Nickel Silicides in Silicon Nanowires

Abstract

� R � 0.75 . The dependence of R on annealing time, t, is close to t 0.5 . The profile of the new phase was described for different combinations of two dimensionless parameters: R/d and Dc/Dsc, where d is the thickness of the high-diffusivity surface layer with diffusion coefficient Dsc, and Dc is the volume diffusion coefficient. After the formation of a continuous layer of a new phase, further growth is controlled exclusively by the interface diffusion of Ni along the nickel silicide surface and Si/Ni2Si interface. The growth kinetics depends on the ratio of diffusion coefficients Dsc/Db, where Db is the interface diffusion coefficient, and may be parabolic or linear. The calculated dependencies were compared with the published experimental results for nickel silicide formation in SiNWs. The analysis performed indicates that surface and interface diffusion of nickel play an important role in the formation of nickel silicides in NWs—a critical finding that should be considered in the design of SiNW FETs.