In this report Molecular Beam Epitaxy (MBE) is shown to produce self-aligned platinum silicide (PtSi) nanoclusters and nanowires on Si (111) substrate near the eutectic point (T = 978 degrees C and 67 at.% Si) of the platinum silicon system. With an added silicon source in the MBE annealing chamber, the formation of two different silicon steps (straight and wave-like) is reported. The steps determine the position and the shape of the thermomigrating PtSi droplets. Nanoclusters preferentially form in the triple point of the wave-like steps while nanoclusters that form on the straight steps combine and grow into silicide nanowires.