Amorphous silicon nitride thin films have been deposited by chemical vapor deposition (CVD) techniques using SiCl4, NH3, H2 gaseous mixtures onto silicon single crystals. The effects of deposition temperature and the flow rates of reactants on the deposition rate have been studied. The characteristics of nitride interface charge have been studied by fabricating metal–nitride–oxide–silicon (MNOS) structure. The experimental results show that the rate of deposition reaction is controlled by surface reactions. The apparent activation energy of silicon nitride deposition reaction is about 29.4 kcal/mol. The nitride charge density was obtained by measuring the flatband voltage of C–V plots. The positive initial nitride charge density in MNOS structure decreases with increasing the deposition temperature or the flow rate of ammonia. The negative electric field was applied to the gate of MNOS structure, and it was found that the trapped positive charge density in silicon nitride film decreases with increasing NH3/SiCl4 ratio of flow rate, and is hardly influenced by the deposition temperature.