We have investigated the formation and growth of iron silicides by the solid phase epitaxy (SPE) and reactive deposition epitaxy (RDE) + post-annealing. Semiconducting beta-FeSi2 was grown on a Si(100) substrate using an electron beam deposition system. In the case of the SPE, although an epitaxial beta-FeSi2 was grown to about 200 Angstrom, the mixed layer of beta-FeSi2 and other phases existed on the epitaxial layer. On the other hands, in the ease of the RDE + post-annealing, the thick beta-FeSi2 film was grown with the thickness of about 3100 Angstrom by post-annealing at 700 degrees C after deposition at 200 degrees C. In the beta-FeSi2 film, the epitaxial beta-FeSi2 grain was grown with a size of about 2500 Angstrom and the epitaxial tendency was B-type. From these results, it seems that the RDE + post-annealing method is more preferable than the SPE fur the growth of a thick epitaxial beta-FeSi2 film.