The epitaxial growth of beta-FeSi2 films produced on flat and patterned Si(001) substrates under various substrate temperatures (T,) with deposition rates of Fe (V-Fe) was investigated by transmission electron microscopy (TEM). In the film deposited on the flat Si(001) substrate, precipitates of flat-bottom shaped beta-FeSi2 and those of round-bottom shaped alpha-FeSi2 were formed at T-s = 500 degrees C and V-Fe = 0.02 nm/s. The beta-FeSi2 adopted the epitaxy to (001)(si) plane, while alpha-FeSi2 selected the epitaxy to {111}(si) planes inside the Si matrix. At T-s = 350 degrees C and V-Fe = 0.01 nm/s, a continuous beta-FeSi2 layer were formed epitaxially on the Si(001) substrate without forming alpha-FeSi2. It was found that the lower temperature and the higher Fe-concentration suppress the formation of alpha-FeSi2 and promote the formation of beta-FeSi2. In addition, the morphology of beta-FeSi2 changed from fine isolated precipitates (islands) to a continuous layer with increasing the deposition rate and the substrate temperature. In the film deposited on the patterned Si(001) substrate at T-s = 500 degrees C and VFe = 0.02 nm/s, on the other hand, both beta- and alpha-FeSi2 precipitates were formed on the top-hills and the valleys of the patterned substrate, while only alpha-FeSi2 precipitates were formed on the sidewalls. These results demonstrate that not only the growth conditions but also geometric situations affect strongly the epitaxial growth of FeSi2 precipitates. (c) 2007 Elsevier B.V. All rights reserved.