We study the adsorption of ferrocene on Si(111) 7x7 at 600 degreesC, and the succeeding growth of SiC islands by annealing at 600-800 degreesC by using scanning tunneling microscopy. The as-adsorbed surface at 600 degreesC still shows remnant 7x7 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 degreesC, but only at the substrate step edges. By annealing at higher temperatures, larger islands are formed and, by annealing at 800 degreesC, some of them show triangular-based trapezoids, which are observed also after flashing at 1130 degreesC. We find that substrate steps play an important role in SiC islands formation as a source of Si atoms at the annealing temperatures studied. (C) 2004 Elsevier B.V. All rights reserved.