Optimization of reaction parameters for synthesis of amorphous silicon nitride powder by vapor phase reaction

Most silicon nitride powders, which are industrially used in various applications under extreme conditions, are produced by the diimide process. The synthesis of diimide is carried out at −50–0 °C using liquid-phase reactants with organic solvent. This process, however, consumes a considerable amount of energy. One promising method for the synthesis of silicon nitride powder which is also energy-efficient is the vapor-phase reaction of SiCl4 with NH3. In this study, the processing parameters of the vapor-phase reaction for the synthesis of silicon nitride were investigated to use this method for producing diimide. The vapor-phase reaction was completed at room temperature with a down-top flow, and solid products were obtained at the bottom of the reactor. Si(NH)2 was decomposed at temperatures above 150 °C according to the result of the TG analysis, which limited the reaction temperature. The reaction temperature was increased with an increase in the flow rates of the reactants and decreased with an increase in the flow rate of the carrier gas. The reaction yield decreased with an increase in the flow rate of the carrier gas. 87% yield was obtained with the optimized reaction condition.