Study on Heat and Mass Transfer in the Magnetic Fields Applied Czochralski Method

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1. Effects of applied magnetic field on convection in melt :Temperature distributions on the melt surface under the conditions with or without magnetic fields were observed by the thermoviewer system. As increasing strength of the applied magnetic field, dominant heat transfer in the melt changed from convective transfer to conductive one. A remote sensing system for convective phenomena under the applied magnetic field conditions was developed. We successfully estimated very weak convection, which could not be observed on the melt surface, by using this method.2. Control of mass transfer by applied magnetic field :A mechanism of oxygen transfer during silicon crystal growth by Czochralski method was clarified. A new magnetic field applied system, Cusp magnetic field, was developed and applied to silicon crystal growth by Czochralski method. We could control the oxygen concentration in the grown crystal with uniform distribution of oxygen along the growth direction and in the wafer.3. Development of strong magnetic field applied system :A vertical Bridgeman with strong magnetic field up to 80, 000 Gauss available was developed.