Suppression of oxidation in nickel germanosilicides by Pt incorporation

Abstract

The effect of oxidation of 10 nm Ni Si0.75 Ge0.25 and 10 nm Ni (10 at. %Pt) Si0.75 Ge0.25 thin films at annealing temperatures ranging from 400 to 800°C has been studied in detail by Rutherford backscattering spectrometry analysis, cross-sectional transmission electron microscopy, energy dispersive x-ray, and sheet resistance measurements. It is observed that for the films without Pt incorporation, almost two-thirds of the germanosilicide is oxidized. The incorporation of a Pt (10 at. %) into Ni not only dramatically reduces the oxidation of the germanosilicides, but also improves the interfacial roughness and morphology. The integral amount of oxygen found in the germanosilicide in the Ni (10 at. %Pt) Si0.75 Si0.25 films [(1.1±0.17) × 1017 at. cm2] is approximately four times less than that of Ni Si0.75 Si0.25 [(4.0±0.28) × 1017 at. cm2]. This result is explained in terms of the roles of the higher melting point and bond energy of PtSi in NiSi and NiGe, and much lower free energy of the formation of platinum oxide. © 2005 American Institute of Physics.