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The chaotic nature of fluid flow within a fluidized bed reactor (FBR), the high surface area of the product which requires special handling to prevent contamination, the size of the reactors and the construction materials present significant engineering challenges, but, once overcome the benefits of the FBR polysilicon production are significant. FBR technology can used with either silane or TCS feed. In this paper, the reaction paths for silane conversion are discussed. Sophisticated predictive modeling and simulation capabilities allow optimization of both reactor design and operating conditions to maximize productivity and reduce reactor downtime. These attributes enable production of high purity polysilicon for both the solar and the semiconductor industries.

A global transport model for industrial Czochralski (CZ) silicon growth is reported in the paper. The model quantifies the temperature fields in all components of the growth system. The heat transport by the conduction, convection (melt and argon flows) and radiation are treated along with the momentum balance in the presence of the static magnetic fields. The crystallization process is modeled by an enthalpy-porosity method in which, the phase change occurs across a finite region defined by volumetric sink/source of heat (enthalpy) and momentum. The momentum sink/source is formulated based on the Darcy's law for porous medium, which is simply a numerical treatment for the isothermal solidification. The flow field in the Czochralski melt predicted by the global enthalpy-porosity based model is compared with that predicted by a more accurate simplified local model. Our studies indicate that the intensity of the flow induced by the presence of the crystal/melt interface is underestimated by the enthalpy-porosity based formulation.

Czochralski Growth of Silicon Crystal (Cz) is extensively used for single crystal manufacturing and most of the Silicon wafers are manufactured by this process. Melt flow in large crucibles, used for growth of large diameter (300mm) crystal, is turbulent in nature. In this study, we present a model for simulating Czochralski crystal growth process for 300mm crystal. This study is mainly focused on effect of crucible rotation on flow and temperature profiles in the melt. Two-dimensional axisymmetric model was used for this purpose which accounts for generated turbulence, heat/ mass transfer with phase change. Investigations show that flow pattern in co-rotation below the crystal is totally opposite that of counter-rotation. Centrifugal force is dominant due to crystal and crucible rotation, which creates vertical upwards or downward flow below the crystal, depending upon the co-rotation or counter rotation. With increase in pull rate, depth of the predicted interface in the melt was also found to be increased. Simulated results will be helpful for optimization of process parameters to achieve better quality of crystals.

Silicon crystals grown by the Czochralski process typically contain many structural imperfections termed microdefects. The formation of all microdefects requires an abundance of one of the intrinsic point defect species of silicon, vacancies and self-interstitials. The evolution of the distribution of microdefects in a growing Czochralski crystal is influenced by its temperature field and the boundary conditions defined by its surfaces. This paper addresses the effects of the lateral surface on the defect dynamics in a crystal growing without an abundance of any intrinsic point defect species, away from the lateral surface. It is shown that, under such conditions, the lateral surface of the crystal induces a moderate vacancy supersaturation in its vicinity, leading to the formation of oxygen clusters and small voids. The vacancy incorporation from the lateral surface of a growing Czochralski crystal is driven by the interplay among the Frenkel reaction, the diffusion of the intrinsic point defects, and their convection.

Modern Czochralski (CZ) silicon crystals contain various large defects known as microdefects that affect the yield and the performance of microelectronic devices. These microdefects are primarily the agglomerates of the intrinsic point defects of silicon, vacancies and self-interstitials, and of oxygen (silicon dioxide). The distribution of microdefects in a CZ crystal is determined by the complex dynamics influenced by various reactions involving the intrinsic point defects and oxygen, and their transport. Two-dimensional oxygen influenced transient defect dynamics in growing CZ crystals is quantified and solved. The Frenkel reaction and the reactions between vacancies and oxygen are considered. The formation of all microdefects is described by the classical nucleation theory. Microdefects are assumed to be spherical clusters that grow by a diffusion-limited kinetics. The predictions of the model agree well with experimental data. Various predictions of the model and experimental results are discussed.