Patent ID: 7404856
Filing Date: 2008-07-29
Classification: C30B

Abstract:
1. A process for growing a single crystal silicon ingot in which the ingot comprises a central axis, a seed end, an opposite end and a constant diameter portion between the seed end and the opposite end having a lateral surface, a radius, R, extending from the central axis to the lateral surface and a nominal diameter of about D mm, the ingot being grown from a silicon melt in a crucible and then cooled from the solidification temperature in accordance with the Czochralski method, the process comprising: growing the constant diameter portion of the crystal at a rate, v, to cause the formation of an axially symmetrical region in which vacancies are the predominant intrinsic point defect, the axially symmetric region being generally cylindrical in shape and having a radius, r rotating the crucible and the ingot in opposite directions during the formation of the axially symmetric region at rates R doping the silicon melt with nitrogen so that about 1×10