IMPURITIES IN COMMERCIAL-SCALE MAGNETIC CZOCHRALSKI SILICON - AXIAL VERSUS TRANSVERSE MAGNETIC-FIELDS

Magnetic Czochralski (MCZ) silicon crystals, 4 inch diameter, were grown in a HAMCO CG-2000 puller, modified to accommodate either a 5000 G superconducting axial field magnet or a 1500 G transverse field electromagnet. The effect of field strength, crystal and crucible rotation rates on the oxygen concentration and distribution are reported for both field configurations. Results for the axial case demonstrate that the oxygen concentration increases in field strength and crystal rotation rate, while crucible rotation rate has only a small effect. In the case of transverse field, it is shown that the oxygen concentration decreases with increase in field strength and decrease in crucible rotation rate. Crystal rotation rate has negligible effect. The macroscopic radial distribution of oxygen using the transverse field is very uniform under most conditions, compared to the axial field and is comparable to the zero field case. While the application of axial field causes a dramatic increase in the effective segregation coefficient of gallium, no such effects were observed (at least for the low fields used) in the segregation behavior of phosphorous in the transverse field. Probable causes for the various observed differences between the two field configurations are discussed. © 1990.