Neutron transmuted magnetic Czochralski grown silicon wafer for power device

The authors examine the preparation of low-cost Si wafers for power devices with diameters of 125 mm and above, using a transversal-superconductive-magnetic-field Czochralski pulling growth method and neutron transmuted doping. The puller has shown a very high pulling rate and low cost. The oxygen concentration in the growing crystal can be kept below 5*10/sup 17/ atoms/cm/sup 3/, as this level of oxygen concentration does not affect the recovery of electrical characteristics and actually makes the silicon wafer more resilient to the high-temperature device production processes. Dislocation loop formation in crystals densely irradiated by fast neutrons and then subjected to high-temperature heat treatment is caused by small grains with a direction slightly different to that of the grand mass crystals. Methods for preventing the formation of loops are described.<>