Effect of Pt addition on Ni silicide formation at low temperature: Growth, redistribution, and solubility

The formation of Ni silicide during the reaction between Ni(5% Pt) and a Si(100) substrate has been analyzed by differential scanning calorimetry (DSC), in situ x-ray diffraction (XRD), cross-sectional transmission electron microscopy (TEM), and H4e+ Rutherford backscattering. The DSC measurements show evidence of the Ni2Si nucleation followed by lateral growth formation. In situ XRD and TEM have been used to investigate the sequence of formation of the silicides. These experiments show that the formations of Ni2Si and NiSi occur simultaneously in the presence of the Pt alloy. The redistribution of platinum at different stages of the Ni silicide growth has been determined. We have estimated the solubility limit of platinum (1 at. % at 573 K) in the Ni2Si phase by extrapolation from a measured value at 1073 K. This redistribution is explained in terms of the solubility limits and the diffusion of Pt in the Ni2Si and NiSi phases. Pt is more likely to reside at the silicide grain boundaries and the interfaces where it can slow down the silicide growth kinetics.