Patent ID: 7217320

Claim:
A process for growing a single crystal silicon ingot in which the ingot comprises a central axis, a seed-cone, a tail-end and a constant diameter portion between the seed-cone and the end-cone having a lateral surface, a radius extending from the central axis to the lateral surface, the ingot being grown from a silicon melt and then cooled from a solidification temperature in accordance with the Czochralski method, the process comprising: controlling (i) a growth velocity, v, (ii) an average axial temperature gradient, G 0 , during the growth of the constant diameter portion of the crystal over the temperature range from solidification to a temperature of no less than about 1325° C., and (iii) a cooling rate of the crystal from the solidification temperature to about 750° C., to cause the formation of a segment wherein an interstitial-dominated axially symmetric region which is substantially free of agglomerated interstitial A defects extends radially inward from the lateral surface, wherein a vacancy-dominated axially symmetric region extends radially inward from the interstitial-dominated region and contains agglomerated vacancy defects, wherein the concentration of agglomerated vacancy defects is greater than 10 3 defects/cm 3 , and further wherein a wafer obtain from said segment, upon being subjected to a subsequent oxidation treatment, has an oxidation induced stacking fault concentration of less than about 50/cm 2 .