The fabrication process of crater structures on Si crystal has been studied by an irradiation of Ar beam and a thermal annealing at 600 degrees C. The fabricated surface was measured by field emission scanning electron microscope and atomic force microscope. The results have shown the controllability of specifications of crater formation such as density, diameter and depth by changing two irradiation parameters, fluence and energy of Ar ions. By changing the fluence over a range of 1 similar to 10 x 10(16)/cm(2), we could control a density of crater 0 similar to 39 counts/100 mu m(2). By changing the energy over a range of 90 similar to 270 keV, we could control a diameter and a depth of crater in 0.8 similar to 4.1 mu m and 99 similar to 229 nm, respectively. The present result is consistent with the previously proposed model that the crater structure would be arising from an exfoliated surface layer of silicon. The present result has indicated the possibility of the crater production phenomena as a hopeful method to fabricate the surface pattern on a micro-nano meter scale.