Study of Ni(Pt) germanosilicides formation on fully-strained Si _0.9Ge_0.1 and Si_0.899Ge_0.1C _0.001 by Raman Spectroscopy

In this work, Raman spectroscopy was used to study the reaction of pure Ni and Ni(Pt 5 at. %) with fully-strained Si_0.9Ge_0.1 and Si_0.899Ge_0.1C_0.001. With pure Ni, it was found that the incorporation of 0.1% C in the substrate resulted in out-diffusion of Ge from the germanosilicide film at a lower rapid thermal annealing (RTA) temperature compared to that of pure Ni on Si_0.9Ge_0.1. This Ge out-diffusion phenomenon is evident from the gradual shift in the NiSi_1-wGe_w (w ≤ x) Raman peak from ∼213 cm ^-1 to higher wavenumbers, closer to 217 cm^-1 as reported for pure Ni/Si, indicating that Ge is being depleted from the film with increasing RTA temperatures. In addition, it was found that severe agglomeration of the germanosilicide film occurred at a lower RTA temperature for the Ni/Si_0.899Ge_0.1C_0.001 system. This corresponds to the observations from the Raman spectra, where a sharp increase in the Si substrate peak at 520 cm^-1 was observed, coupled with the appearance of the transverse acoustic (TA)- phonon peak of Si at 301 cm^-1. When Pt was introduced into the Ni film, significant improvements were observed for the germanosilicide films on Si_0.9Ge_0.1 and Si _0.899Ge_0.1C_0.001 substrates, both in terms of Ge out-diffusion and agglomeration. Initial findings show that the addition of Pt promotes the formation of the low resistivity mono-germanosilicide phase at temperatures as low as 300°C.