Effect of asymmetric magnetic fields on crystal–melt interface in silicon CZ process

Silicon single crystals are grown by Czochralski (CZ) method under different growing conditions. The different shapes of the crystal–melt interface are obtained with various magnetic fields. Effects of zero-Gauss plane (ZGP) shape and magnetic intensity (MI) on the crystal–melt interface in the crystal are experimentally investigated. Variations in crystal–melt interface allow interpretation of crystal defect generation mechanism with regards to interface shapes. The shape of ZGP is not flat but also parabolic, which is due to magnetic ratio (MR) of the lower-to-upper current densities in the configurations of the cusp-magnetic fields. As MR increases, the crystal–melt interface becomes more concave. It means that the hot melt can be easily transported to the crystal–melt interface with increasing the MR. Effective shape of the crystal–melt interface is found to depend on the magnetic field in cusp-magnetic CZ method. The experimental results are compared with other studies and discussed.

► Shape of the crystal–melt interface is found to depend on the magnetic field.
► The interface becomes more concave with increasing MR.
► Ci/Cv margin for defect-free crystal increases with increasing MR less than MR=1.8.
► The optimal position of ZGP for defect-free crystal is to locate at the interface.
► It can control oxygen concentration without changing crystal defect quality.