Patent ID: 8043427

Claim:
A method for producing semiconductor wafers of silicon, comprising pulling a single crystal growing at a phase boundary from a melt contained in a crucible and cutting semiconductor wafers from the single crystal, wherein heat is delivered to a center of the phase boundary during pulling and a radial profile of a ratio V/G from the center to an edge of the phase boundary is controlled, with G being the temperature gradient perpendicular to the phase boundary and with V being the pull rate at which the single crystal is pulled from the melt, wherein the radial profile of the ratio V/G is controlled so that the effect of thermomechanical stress fields in the single crystal which adjoin the phase boundary is compensated with respect to creation of intrinsic point defects, by keeping the temperature gradient G in a region of the single crystal which is under compressive stress and adjoins a central zone of the phase boundary greater than in a region which is under tensile stress and adjoins an edge region of the single crystal and the phase boundary, adjusting the radial profile of V/G so that V/G is lower in the region of compressive stresses and higher in the region of tensile stresses, than a critical ratio V/G which is a prerequisite in the case of a flat phase boundary such that a defect-forming excess of point defects is not created, wherein the radial profile of V/G is adjusted so that (V/G) t /(V/G) c is greater than 1.5, where (V/G) c is the lowest ratio V/G in the region which is under compressive stress and (V/G) t is the highest ratio V/G in the region which is under tensile stress.