Silicon nanocrystals have been produced by thermal annealing of SiNx thin film obtained by low pressure chemical vapor deposition using a mixture between disilane and ammonia. Morphological, structural, and photoluminescence properties of the thin film were investigated using X-ray diffraction, scanning electron microscopy, Raman spectroscopy and photoluminescence spectroscopy. The results revealed a high crystallinity of film with a crystalline volume fraction exceeded 70 %, and a dominance of silicon nanocrystallites having the sizes within the range 2.5-5 nm and density ~1.98.10 12 /cm 2. The PL peaks consist of nanocrystalline silicon and amorphous silicon. The luminescence from the silicon nanocrystals was dominant.