西门子法生产多晶硅的热力学

Thermodynamic Study on Production of the Multicrystalline Silicon by Siemens Process

应用有关热力学数据研究了与西门子法相关的“Si-Cl-H”三元系的复杂化学反应,分别绘制了在体系中存在的15个化学反应的△rG m-T图和Kp -T图;还给出在不同压强和不同SiHCl3/H2初始比例时的平衡气相成分、η-产率随温度的变化图以及在不同的压强下α因数随SiHCl3初始物质的量的分数的变化图。热力学研究结果表明,高温、低压和小的SiHCl3/H2初始物质的量的比对SiHCl3还原有利;α因数随着SiHCl3初始物质的量的比x4^0的增大而增大。

The complex chemical reactions in the Si-Cl-H system with relation to Siemens process were studied by means of calculation based on the thermodynamic data selection. Diagrams of △ Gm and Kp for the fifteen chemical reactions in this system versus temperature were plotted; diagrams of the equilibrium gas phase composition and η-yield were presented as a function of temperature for different total pressure and initial molar ratio of SiHClJH2; diagrams of α-yield were presented as a function of initial molar fraction （x4^0） of SiHCl3 for different total pressures. The results from this thermodynamic study show that high temperature, low pressure and low initial molar ratio of SiHClJH2 are favourable to the reduction of SiHCl3 by H2 and α-factor of Si increases with initial molar fraction （x4^0） of SiHCl3 increasing.