In situ study of the growth properties of Ni-rare earth silicides for interlayer and alloy systems on Si(100)

Demeulemeester, J; Knaepen, W; Smeets, D; Schrauwen, A; Comrie, C M; Barradas, N P; Vieira, A; Detavernier, C; Temst, K; Vantomme, A

In situ study of the growth properties of Ni-rare earth silicides for interlayer and alloy systems on Si(100)

Journal Article

2012

Journal Title

Journal of Applied Physics

Link to Journal

https://dx.doi.org/10.1063/1.3681331

Department

Department of Physics

Faculty

Faculty of Science

Abstract

We report on the solid-phase reaction of thin Ni-rare earth films on a Si(100) substrate, for a variety of rare earth (RE) elements (Y, Gd, Dy, and Er). Both interlayer (Ni/RE/〈Si〉) and alloy (Ni-RE/〈Si〉) configurations were studied. The phase sequence during reaction was revealed using real-time x-ray diffraction whereas the elemental diffusion and growth kinetics were examined by real-time Rutherford backscattering spectrometry. All RE elements studied exert a similar influence on the solid phase reaction. Independent of the RE element or its initial distribution a ternary Ni 2Si2 RE phase forms, which ends up at the surface after NiSi growth. With respect to growth kinetics, the RE metal addition hampers the Ni diffusion process even for low concentrations of 2.5 at. %, resulting in the simultaneous growth of Ni-rich silicide and NiSi. Moreover, the formation of Ni 2Si2 RE during NiSi growth alters the Ni diffusion mechanism in the interlayer causing a sudden acceleration of the Ni silicide growth. Besides a significant effect on the silicide growth, we have found that adding 5 at. % Er (relative to Ni) lowers the NiSi Schottky barrier height on n-type Si(100) by approximately 0.1 eV for the interlayer and alloy configuration.