动态流态化多晶硅还原过程与无定形硅粉成核机理研究

Fluidized bed operation has the capabilities of high-throughput, continuous operation and low energy cost. It made fluidized bed (FB) production of polysilicon, which is called fluidized Chemical Vapor Deposition (FCVD), more attractive. Because silane has a low deposition temperature, and can be completely converted in a non-reversible reaction, it is attractive for use in FB operation. But there are various complex physical and chemical phenomenon in the process, which include coupled gas phase reaction and stiff surface reaction, particle diameter with particle size distribution varying, etc. Especially, unwanted fines are homogeneously nucleated, which seriously reduce the product quality, and restrict the application of FCVD. Study on the above phenomenon has become a hot subject in present silicon material and chemical engineering. The project plan to research the mechanism of amorphous silicon powder nucleation, and based on the mechanism, to set up a space-time multi-scale model of the coupled gas-phase, gas-solid chemical reactions and fluid mechanics in a fluidized bed reactor. The model describes the broken and coalescence of silicon particle based on particle in microscopic scale, and analyzes the gas solid flow and the process of FCVD by CFD in macroscopic scale. Numerical simulation and experimental tests will be carried out for posting the mechanism of amorphous silicon powder nucleation and the mechanism of the process of the fluidized chemical vapor deposition of polysilicon.

流态化多晶硅还原方法因具有能耗低、产能高，易连续化操作等优点而备受关注。但过程中的物理化学现象复杂且相间耦合作用强烈，尤其是硅烷热分解生成的超细无定形硅粉，严重影响产品质量，制约了流态化技术的应用。上述过程机理目前成为硅材料、化学工程等领域的研究难点和热点。本项目拟利用硅烷族气体反应模型研究无定形硅粉成核机理，并以此从微观上描述无定形硅粉的聚并、长大等行为；宏观上用计算流体动力学方法，同时耦合硅烷均相和非均相反应模型，分析气固两相流动，传热和传质规律，实现流态化多晶硅化学气相沉积过程的时空多尺度分析。申请者试图以数值研究结合实验揭示流态化多晶硅化学气相沉积过程机理和无定形硅粉成核机理，从而提出流态化多晶硅化学气相沉积的最优化操作条件和方法。为动态流态化多晶硅还原过程的应用提供理论依据，丰富气相成核理论，拓展流态化理论研究。

流态化多晶硅还原方法因具有能耗低、产能高，易连续化操作等优点而备受关注。但过程中的物理化学现象复杂且相间耦合作用强烈，尤其是硅烷热分解生成的超细无定形硅粉，严重影响产品质量，制约了流态化技术的应用。上述过程机理目前成为硅材料、化学工程等领域的研究难点和热点。本项目利用硅烷族气体反应模型研究无定形硅粉成核机理，并以此从微观上描述无定形硅粉的聚并、长大等行为；宏观上用计算流体动力学方法，同时耦合硅烷均相和非均相反应模型，分析气固两相流动，传热和传质规律，实现流态化多晶硅化学气相沉积过程的时空多尺度分析。. 项目构建了无定形硅粉的成核模型，并通过数值模拟和实验研究建立了无定形硅粉成核的定量预测模型，为控制无定形硅粉奠定理论基础；通过分析不同尺度物理化学作用间的耦合作用规律，明确不同尺度模型间的参数传递机制，建立了描述复杂系统时空多尺度模型的理论和方法，从而实现了对流态化多晶硅CVD过程的时空多尺度分析，突破现有研究主要采用单一尺度模型考察流态化多晶硅CVD过程的局限；同时从颗粒表面沉积入手，分析流态化传热传质与CVD 间的相互影响规律，考察由于颗粒表面CVD、碰撞、聚并等现象引起颗粒尺寸分布变化对动态流态化条件的影响，丰富了流态化理论研究。. 项目实施过程中，发表论文24篇，其中SCI收录1篇，EI收录6篇，授权发明专利7项，并获山东省专利奖一等奖1项；本项目为动态流态化多晶硅还原过程的应用提供理论依据，丰富了气相成核理论，拓展了流态化理论研究。