Influencing factors of silicon productivity during production of polycrystalline silicon by zinc reduction process

Some factors influencing silicon productivity were studied for producing polycrystalline silicon by zinc reduction.When the reaction reached equilibrium,the relation between gas phase compositions and temperature was analyzed at the Zn/SiCl₄ molar ratio of 2,4 and 8 under the pressure of 0.1,0.3 and 0.6MPa,respectively.The changes of silicon productivity with gas pressure,temperature and Zn/SiCl₄ molar ratio were discussed.The results show that lower temperatures,suitable pressures and higher Zn/SiCl₄ molar ratios have a positive effect on the zinc reduction process.The major side-reactions which affect the silicon productivity were then determined.Finally the optimum operating conditions for the zinc reduction process were presented as 1200K,0.2MPa and the Zn/SiCl₄ molar ratio of 4.Under the optimum operating conditions,the theoretical silicon productivity can be 90.3%.