beta -FeSi2 is a new material showing semiconductor properties, which has been characterized to consist of the abundant and not toxic constituents, iron and silicon. The ion implantation method is one of the most useful techniques to make a good quality beta -FeSi2 phase on a Si wafer, although it is polycrystalline. Using field-emission transmission electron microscopy, the formation process of the beta -FeSi2 particles and layer-grown beta -FeSi2 phase was investigated. With annealing at 800 degreesC after Fe-56(+) ion implantation at energy of 100 keV, an amorphous-like damaged layer changed to the single phase of beta -FeSi2 and Si single crystal phase. It was characterized that the precipitation always occurred from the Si wafer surface, resulting in the possibility of the formation of a layered beta -FeSi2 structure on the Si wafer. By controlling the Fe concentration at the damaged layer with multiple ion implantation, a layer grown beta -FeSi2 poly-crystals was obtained. The morphology of a grain of the layered poly-crystals is dendrite, of 5-10 mum in diameter. High resolution electron microscope observations further revealed that the each dendrite grain of beta -FeSi2 consists of more fine domains of 50-100 nm in size, resulting in the release of a large lattice misfit strain for the Si single crystal.