We have studied the interrelationship between the morphology of oxide precipitates and the p-n junction leakage current in Czochralski silicon crystals. It is well known that the p-n junction leakage current can be used to measure the electric characteristic near the surface of a silicon wafer. After we measured the p-n junction leakage current, we studied the morphology of the oxide precipitates under the p-n junction by transmission electron microscopy. The junction leakage current characteristics are almost the same for both preannealing at 780°C for 24 h and 1000°C for 7 h and for preannealing at 1200°C for 0.5 h. In addition, the oxide precipitates near the surface were almost all in the form of polyhedrals in both preannealing types. However, in a dose of ten times for preannealing at 1200°C for 0.5 h, the morphology of oxide precipitates near the surface were polyhedrals with dislocation. That is to say, the morphology of oxide precipitates has been affected by a dose of p+ ion implantation. In this paper, we discuss the effects of junction leakage current characteristics on the morphology of oxide precipitates in the near‐surface area. © 1999 The Electrochemical Society. All rights reserved.