Influence of different types of magnetic fields on the interface shape in a 200 mm Si-EMCZ configuration

Three-dimensional time-dependent simulations were carried out in order to predict the heat transport and interface shape in a 200 mm diameter silicon electromagnetic Czochralski (EMCZ) configuration under the influence of two types of magnetic fields: (a) a vertical magnetic (VMF) field and (b) a cusp magnetic field (CMF). It was found that for a CMF, the interface deflection is much higher (more than two times) than in the case of a VMF. The same effect of increasing the interface deflection was also observed in experiments where a strongly convex interface shape towards the crystal with a deflection of about 40 mm has been observed. In comparison, in a VMF experiment, a convex interface with a deflection of about 10 mm has been measured. The difference of the interface shapes is a result of the influence of the magnetic field configuration on the convective heat flows in the melt. In the case of CMF, the hot melt can be easily transported to the solid–liquid interface causing the strong interface deflection, whereas for a VMF, the radial heat transport is suppressed due to the melt rotation.