Nanostructured TiOx film on Si substrate: room temperature formation of TiSix nanoclusters

We present a morphologic and spectroscopic study of cluster-assembled TiOx films deposited by supersonic cluster beam source on clean silicon substrates. Data show the formation of nanometer--thick and uniform titanium silicides film at room temperature (RT). Formation of such thick TiSix film goes beyond the classical interfacial limit set by the Ti/Si diffusion barrier. The enhancement of Si diffusion through the TiOx film is explained as a direct consequence of the porous film structure. Upon ultra high vacuum annealing beyond 600 C, TiSi2 is formed and the oxygen present in the film is completely desorbed. The morphology of the nanostructured silicides is very stable for thermal treatments in the RT--1000 C range, with a slight cluster size increase, resulting in a film roughness an order of magnitude smaller than other TiOx/Si and Ti/Si films in the same temperature range. The present results might have a broad impact in the development of new and simple TiSi synthesis methods that favour their integration into nanodevices.