We study the adsorption of ferrocene on Si(111) 7×7 at 600 °C, and the succeeding growth of SiC islands by annealing at 600–800 °C by using scanning tunneling microscopy. The as-adsorbed surface at 600 °C still shows remnant 7×7 structure and, as annealing time is prolonged until 60 min, granules grow to an average width of 1.0 nm. The islands start to grow by annealing at 650 °C, but only at the substrate step edges. By annealing at higher temperatures, larger islands are formed and, by annealing at 800 °C, some of them show triangular-based trapezoids, which are observed also after flashing at 1130 °C. We find that substrate steps play an important role in SiC islands formation as a source of Si atoms at the annealing temperatures studied.