beta-SiC nanoprecipitates can be patterned in crystalline silicon with an almost monomodal size distribution by simultaneous-dual-beam of C+ and Si+ ion implantations at 550 A degrees C. Their shape appears as spherical (average diameter similar to 4-5 nm) ,and they are in epitaxial relationship with the crystalline silicon matrix. The narrow size distribution follows the left wing of the carbon distribution where the nuclear ion stopping, and thus the point defect generation rate is largest. This observation allows us to conclude that the induced damage act as sinks for C atoms leading to the SiC nanoprecipitates formation centered at the maximum of the simulated damage distribution. The nuclear reaction analysis, X-ray diffraction, Raman spectroscopy, and transmission electron microscopy techniques were used to characterize the samples.