Crystal Defects in Highly Boron Doped Silicon

Si wafers with boron concentrations up to 2 10 19 cm 3 were characterized by delineating defects with SC1 solution and analyzing them with respect to crystal originated particles (COP). No oxidation induced stacking fault (OSF) ring appears, and the whole wafer displays a homogeneous COP density after SC1 treatment for low boron doped ingots in a resistivity range of several ohms centimeter and appropriate pulling conditions. Without modification of the crystal pulling process but increasing boron concentration the radial COP distribution changes. The area with a high COP density shrinks and vanishes in the center of the wafer when the boron concentration approaches a level of about 10 19 cm -3 . Adjacent to the area of high COP density an OSF ring is found, similar to the case of low boron doped material at reduced pulling rate. It is assumed that boron doping at a sufficiently high level modifies the balance of vacancies and interstitials generated in the crystal pulling process and changes the radial defect distribution in the silicon crystals.