Effect of a shaped magnetic field on Czochralski silicon growth

We report results of an experimental study of the effect of a shaped magnetic field on the CZ growth of silicon. The field is produced by means of two opposing superconducting solenoids and is configured to produce a field which is predominantly normal to the crucible wall. This configuration is designed to lead a high degree of damping of the flows up the crucible wall, so causing a significant reduction in the oxygen content of the melt. In addition, by location the crystal/melt interface in the plane of symmetry of the field, a region of zero axial magnetic flux, the detrimental effects of an axial field on radial uniformity can be minimised. By choice of appropriate growth conditions, crystals can be grown with oxygen contents variable over a wide range. The radial uniformity of both dopant and oxygen is comparable to that in crystals grown under corresponding zero field conditions. The magnetic field configuration is amenable to scaling the larger diameters.