Hydrogenation of Silicon Tetrachloride in Microwave Plasma

This study investigated the hydrogenation of silicon tetrachloride (SiCl4) in microwave plasma. A new launcher of argon (Ar) and hydrogen (H-2) plasma was introduced to produce a non-thermodynamic equilibrium activation plasma. The plasma state exhibited a characteristic temperature related to the equilibrium constant, which was termed "Reactive Temperature" in this study. Thus, the hydrogenation of SiCl4 in the plasma could easily be handled with high conversion ratio and very high selectivity to trichlorosilane (SiHCl3). The effects of SiCl4/Ar and H-2/Ar ratios on the conversion were also investigated using a mathematical model developed to determine the optimum experimental parameters. The highest hydrogenation conversion ratio was produced at a H-2/SiCl4 molar ratio of 1, with mixtures of SiCl4 and H-2 to Ar molar ratio of 1.2 to 1.4. In this plasma, the special system pressure and incident power were required for the highest energy efficiency of hydrogenating SiCl4, while the optimum system pressure varies from 26.6 to 40 kPa depending on input power, and the optimum feed gas (H-2 and SiCl4) molar energy input was about 350 kJ.mol(-1).