Patent ID: 6897084

Claim:
A wafer sliced from a single crystal silicon ingot grown in accordance with the Czochralski method, the wafer comprising: a front surface, a back surface, an imaginary central plane approximately equidistant between the front and back surfaces, a front surface layer which comprises a region of the wafer between the front surface and a distance, D 1 , measured from the front surface and toward the central plane, and a bulk layer which comprises the imaginary central plane but not the front surface layer, and a non-uniform concentration of crystal lattice vacancies, the concentration of the vacancies in the bulk layer being greater than the concentration of vacancies in the front surface layer, wherein (i) D 1 is at least 5 microns but less than 30 microns, (ii) the surface layer has a resistivity of at least 100 ohm cm, and (iii) upon being subjected to an oxygen precipitation heat-treatment at a temperature in excess of about 700° C., the surface layer has less than about 1×10 7 cm −3 oxygen precipitates while the bulk layer has more than about 1×10 7 cm −3 oxygen precipitates.