Oxygen transfer during single silicon crystal growth in Czochralski system with vertical magnetic fields

Oxygen transfer in silicon melts during crystal growth under vertical magnetic fields is investigated numerically and experimentally. A three-dimensional numerical simulation, including melt convection and oxygen transport, is carried out to understand how oxygen transfers in the melt under magnetic fields. Oxygen concentrations in single silicon crystals grown from the melt under these magnetic fields are experimentally measured by using an infrared absorption technique. The results obtained are compared to results from a numerical simulation. An anomalous increase is observed in the oxygen concentration of the grown crystals under a magnetic field of about 0.03 T. The cause of this anomaly is identified as Benard instability, since the temperature at the bottom of the crucible is higher than that at interface. When the temperature at the bottom is decreased, the Benard cell can be removed, and a monotonic decrease in the oxygen concentration in the single silicon crystals can be observed.