Advances in the formation of C54TiSi 2 with an interposed refractory metal layer: some properties

Abstract

We have shown recently that the formation of C54TiSi 2 is enhanced by using a thin refractory metal layer of either Mo or Ta deposited between Ti films and Si substrates, through the formation of a template layer composed of (Mo,Ti)Si 2 or TaSi 2. We show in this paper that the interposed layer also influences the morphology and thermal stability of the TiSi 2 films formed. Certain improvement in the surface morphology of TiSi 2 is found with the TiSi 2 formed using either Ti/Mo or Ti/Ta, as compared to the TiSi 2 formed with just Ti. The thermal stability of TiSi 2 is also improved slightly with the presence of Ta. The impact of the Mo interposing layer on the thermal stability of TiSi 2 is however somewhat complex and dependent on the Si substrate; the temperature at which a continuous TiSi 2 film breaks into discrete grains is increased by about 50°C on monocrystalline Si substrates, but it is decreased by about 75°C on polycrystalline Si substrates, in comparison with the TiSi 2 formed with pure Ti.