Patent ID: 7282095

Claim:
A silicon single crystal pulling method comprising: arranging an upper coil ( 51 ) and a lower coil ( 52 ) with a predetermined gap therebetween in a perpendicular direction outside a chamber ( 11 ) in which a quartz crucible ( 13 ) is provided; generating a cusp magnetic field ( 53 ) having an intensity of 50 gausses or above which runs through a neutral plane ( 53 a ) between the upper coil ( 51 ) and the lower coil ( 52 ) from respective coil centers of the upper coil ( 51 ) and the lower coil ( 52 ) by allowing opposite currents to flow through the upper coil ( 51 ) and the lower coil ( 52 ); rotating the quartz crucible ( 13 ) at a predetermined rotation speed; supplying an inert gas into the chamber ( 11 ) from an upper part of the chamber ( 11 ) so that the inert gas flows down in a heat shielding member ( 36 ) provided in the chamber ( 11 ); rotating a silicon single crystal ingot ( 25 ) including a top-side ingot ( 25 a ) and a bottom-side ingot ( 25 b ) from the silicon melt ( 12 ) at a predetermined rotation speed; and pulling up the silicon single crystal ingot ( 25 ) from a center of the heat shielding member ( 36 ) at a pulling rate with which a perfect region where interstitial silicon point defect agglomerates and vacancy point defect agglomerates do not exist is provided in the silicon single crystal ingot ( 25 ), wherein the heat shielding member ( 36 ) comprises: a cylindrical portion ( 37 ) whose lower end is positioned above a surface of the silicon melt ( 12 ) with a gap therebetween and which surrounds an outer peripheral surface of the ingot ( 25 ); and a bulge portion ( 41 ) which is provided to bulge in an in-cylinder direction at a lower portion of the cylindrical portion ( 37 ) and has a heat storage member ( 47 ) provided therein, wherein an inner peripheral surface of the heat storage member ( 47 ) is formed in such a manner that a height (H 1 ) is not smaller than 10 mm and not greater than d/2 and a minimum gap (W 1 ) with respect to the outer peripheral surface of the ingot ( 25 ) is not smaller than 10 mm and not greater than 0.2 d where d is a diameter of the ingot ( 25 ) and not smaller than 100 mm, and wherein a flow quantity of the inert gas flowing down between the bulge portion ( 41 ) and the ingot ( 25 ) when pulling up the top-side ingot ( 25 a ) of the silicon single crystal ingot ( 25 ) is larger than a flow quantity of the inert gas flowing down between the bulge portion ( 41 ) and the ingot ( 25 ) when pulling up the bottom-side ingot ( 25 b ) of the silicon single crystal ingot ( 25 ).