TED-AJ03-112 EFFECT OF HIGH FREQUENCY MAGNETIC FIELD ON CZ SILICON MELT CONVECTION
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概要
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Melt flow structure during the silicon single crystal growth process strongly affects the crystal quality. Therefore, melt convection control technique should be developed to obtain the high quality single crystal. For this purpose, we proposed a high frequency magnetic field applied method to control the melt convection, and numerically investigated the validity of this method for the silicon Czochralski (CZ) crystal growth process. Figure A-1 shows the schematic model for numerical simulation. In this model, axisymmetric system and flat melt-crystal interface shape are assumed. The induction coil position, which will strongly affects the melt flow structure, is assumed as placed at the slightly above the melt free surface. Further, the crystal/crucible rotation, which is usually applied in the industrial process, is omitted. Under these assumptions, the governing equation is solved by the finite difference scheme. Figure A-2 shows the typical result for flow (left hand side) and temperature (right hand side) fields inside the silicon melt at t=0.01 in dimensionless time. This figure was obtained by assuming the applied frequency of 500kHz and the applied induction coil current of 216A for the crucible radius of 0.01m. On the flow field, the solid line indicates the clockwise flow direction and the dashed line indicates the counterclockwise flow direction. As shown in this figure, although the clockwise flow is existed at the free surface near the crucible wall, indicated by the solid line, almost all region of the melt is governed by counterclockwise flow, indicated by dashed line. This kind of flow structure is usually obtained by the crystal rotation. Therefore, the high frequency magnetic field has almost the same effect of the crystal rotation. On the temperature field, almost flat isotherm, which is needed for high quality crystal growth, is formed below the crystal by this flow characteristic. Further, it is clarified that the flow field is unsteady and fluctuated with time by probing the temperature inside the melt due to the mixing effect of the high frequency magnetic field. The effect of this fluctuation on the crystal quality is still uncertain, however, it could be concluded that the high frequency magnetic field applied method is useful to control the melt convection and to form the flat isotherm below the crystal.[figure]
- 一般社団法人日本機械学会の論文
著者
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Someya Satoshi
Institute For Energy Utilization Aist
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Munakata Tetsuo
Institute For Energy Utilization National Institute Of Advanced Industrial Science And Technology
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TANASAWA Ichiro
Department of Mechanical Engineering, Nihon University
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Tanasawa Ichiro
Department Of Mechanical Engineering Nihon University