Silicon wafers especially prepared to meet a customer’s needs in the production of semiconductor memory circuits are studied with synchrotron section topography. A well-defined uniform denuded zone below the surface with a width of 12 to 24 mu m is observed. The concentration and the size of the oxygen-related defects in the bulk are independent of the location along the crystal ingot, from which the wafer originates, and of that along the wafer diameter.