Single crystal pulling apparatus

摘要

The present invention provides an improved single crystal pulling apparatus for pulling a single crystal semiconductor such as silicon or gallium arsenide. The apparatus of the present invention comprises a gas tight container, a crucible which is disposed inside the container, a heater, and a pair of coils to apply a cusp magnetic field in the semiconductor melt. The crucible is separated into two regions by a cylindrical partition body, and an outside region is used to supply source material and to melt the source material and an inside region is used for pulling up the single crystal. The inside and outside regions are communicated with the communication passage provided at the bottom of the partition body. Electrical currents in opposing directions are applied to a pair of coils for generating in the melt a cusp magnetic field which includes a vertical portion and a horizontal portion relative to the crucible. By positioning the vertical portion of the cusp magnetic field at the position of the communication passage and the horizontal portion below the semiconductor melt, the flow rate of the melt passing through the communication passage is reduced and the convection within the melt is suppressed. Consequently, high quality semiconductor single crystals can be obtained.