A Czochralski method of producing a single crystal silicon ingot having a uniform thermal history. In the process, the power supplied to the side heater is maintained substantially constant throughout the growth of the main body and end-cone of the ingot, while power supplied to a bottom heater is gradually increased during the growth of the second half of the main body and the end-cone. The present process enables an ingot to be obtained which yields wafers having fewer light point defects in excess of about 0.2 microns, while having improved gate oxide integrity.