We examined effects of ion implantation doses, annealing temperature and time on ion-beam synthesis (IBS) of polycrystalline beta -FeSi2 using Raman spectroscopy. It was confirmed that at very low Fe concentration doses (up to 1 x 10(16) ions/cm(2)), fine grains of beta -FeSi2 and a small amount of fluorite gamma -FeSi2 may precipitate after annealing at 800 degreesC. In the case of high dose (> 1 x 10(17) ions/cm(2)), the clear Raman lines showed that beta -FeSi2 grows after annealing at 800 degreesC. However, we observed an outstanding Raman line at 324 cm(-1) and broad features at 300-450 cm(-1) after annealing at 600 and 700 degreesC. These Raman features can be considered to be due to presence of gamma -FeSi2 and lattice imperfections in the samples. Furthermore, we evaluated improvement of crystalline quality with increasing the annealing time and temperature using a clear blue shift of the Raman line and increase of the intensity-ratio of two Raman lines at similar to 192 and similar to 246 cm(-1), theta = (I-192/I-246),