We have exploited the possibility of obtaining SiC by annealing at selected increasing temperatures cluster-assembled carbon films deposited in situ by a supersonic beam onto Si(100)-(2x1) substrates. We measured the evolution of the valence bands and of the Si 2p and C 1s core level spectra to monitor the thermal induced effects in the atomic concentrations and the electronic structure at the interface. Our results indicate that at the interface Si C bonds are already formed at 700 o C, a temperature that is significantly lower (~50 o C) than found in literature by using other C-based precursors for SiC growth on Si surfaces. Supersonic carbon cluster beam deposition seems to be promising for the growth of SiC films on Si surfaces with improved interface quality.