硅烷热解气相沉积反应模型及流化床CVD反应器的数值模拟

发布时间：2018-03-11 13:19

本文选题：硅烷　切入点：多晶硅　出处：《华东理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：发展太阳能光伏产业是解决化石燃料短缺和环境污染的有效途径。作为主要的太阳能转换材料,高纯多晶硅制备工艺的完善和发展是目前亟待解决的关键问题。以硅烷为原料的流化床法,具有能耗低、成本低、污染小的优点,是太阳能光伏产业发展的关键技术之一。由于硅烷的气相沉积反应机理复杂,与流化床内的气-固流动相互耦合,使流化床CVD反应器的研究开发和放大设计面临较大困难。本文采用计算流体力学的方法(CFD),用群体平衡模型(PBM)耦合硅烷热解反应动力学,预测反应器内流动情况和颗粒生长过程,为流化床CVD反应器的开发提供理论支持。首先,分析了硅烷热解多晶硅气相沉积反应机理,比较了现有硅烷热解反应模型。采用Ho等人提出的气相和表面反应机理,结合二维边界层反应模型和CHEMKIN软件,对水平单基片CVD反应器进行模拟分析,将计算结果与文献报道的实验数据进行比较,发现一致性良好,从而验证了上述反应机理的模拟精度,表明该机理可用于硅烷流化床化学气相沉积过程的CFD耦合模拟。其次,模拟了小型流化床CVD反应器内流动与反应的耦合过程。采用CFD-PBM耦合模型和修正的Ho的反应动力学机理,对文献报道的流化床多晶硅生长实验装置进行模拟计算,预测颗粒增长速率。结果表明:在流化床反应条件下,Ho的反应动力学模型中硅微粉前躯体的再沉积过程十分显著;当硅烷摩尔分数分别为0.2和0.5时,Ho的反应动力学模型计算出来的颗粒增长速率略高于实验结果;当硅烷摩尔分数分别为0.57和0.8时,由于硅微粉前躯体浓度很高,部分转化为稳定的硅微粉,可供再沉积的量减少。将H2SiSiH2再沉积反应速率方程指前因子缩小10倍,模拟得到的增长速率与实验结果拟合良好。
[Abstract]:The development of solar photovoltaic industry is an effective way to solve the shortage of fossil fuels and environmental pollution. The improvement and development of high purity polysilicon preparation process is a key problem to be solved. The fluidized bed process using silane as raw material has the advantages of low energy consumption, low cost and low pollution. It is one of the key technologies in the development of solar photovoltaic industry. Because of the complex mechanism of vapor deposition reaction of silane, it is coupled with gas-solid flow in fluidized bed. It is difficult to develop and amplify the fluidized bed CVD reactor. In this paper, the method of computational fluid dynamics (CFD) is used to predict the flow and particle growth process of the reactor by coupling the pyrolysis kinetics of silane with the group equilibrium model. It provides theoretical support for the development of fluidized bed CVD reactor. Firstly, the mechanism of silane pyrolysis polysilicon vapor deposition reaction is analyzed, and the existing models of silane pyrolysis reaction are compared. Combined with the two-dimensional boundary layer reaction model and CHEMKIN software, the horizontal monolithic CVD reactor was simulated and analyzed. The calculated results were compared with the experimental data reported in the literature. Thus, the simulation accuracy of the above reaction mechanism is verified, and it is shown that the mechanism can be used in the CFD coupling simulation of chemical vapor deposition process in silane fluidized bed. Secondly, The coupling process of flow and reaction in a small fluidized bed CVD reactor was simulated. Using the CFD-PBM coupling model and the modified Ho reaction kinetic mechanism, the experimental device for polysilicon growth in fluidized bed was simulated and calculated. The results show that the redeposition process of the body in front of silicon powder is very significant in the kinetic model of Ho reaction in fluidized bed reaction. When the molar fraction of silane is 0.2 and 0.5, the particle growth rate calculated by the reaction kinetics model is slightly higher than that of the experimental results, and when the molar fraction of silane is 0.57 and 0.8, respectively, the concentration of the body in front of silicon powder is very high. The redeposition rate of H _ 2Si _ SiH _ 2 was reduced by 10 times to the pre-exponential factor of H _ 2Si _ SiH _ 2 redeposition reaction rate equation, and the simulated growth rate fitted well with the experimental results.
【学位授予单位】：华东理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM615

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