Effect of intrinsic point defects on copper precipitation in large-diameter Czochralski silicon annealed at 1100 °C under air cooling was studied by means of scanning infrared microscopy (SIRM), optical microscopy (OM), and transmission electron microscopy (TEM). The SIRM images showed that, in the A-defect zone of the Cu-contaminated silicon wafers, the copper-precipitate colonies with larger size were observed, while in the D-defect zone almost no copper precipitates could be observed. However, the OM results revealed that the density of etching pits in the D-defect zone was higher than that in the A-defect zone, indicating that the copper precipitates with smaller size and higher density formed in the D-defect zone. The TEM investigation showed that the size of copper precipitate colonies in the A-defect zone was about 300 nm, while that in the D-defect zone was about 50 nm. It is considered that as-grown vacancies in the D-defect zone enhanced the nucleation of copper precipitates but hindered their growth, whereas the role of as-grown interstitial silicon on copper precipitation was inverse. © 2003 American Institute of Physics.