Oxygen precipitation in heavily phosphorus-doped Czochralski silicon: effect of nitrogen codoping

Oxygen precipitation (OP) in the conventional and nitrogen-codoped heavily phosphorous (P)-doped Czochralski silicon (CZ-Si) wafers subjected to various low- (650-850 deg C) and high-temperature (1050 deg C) two-step annealing conditions have been comparatively investigated. It was found that the nucleation annealing at 650 deg C led to remarkable OP and the resulting bulk micro defect densities were nearly the same in both kinds of silicon wafers. While in the case with the nucleation annealing at 750 or 850 deg C, the conventional heavily P-doped CZ-Si featured slight OP, in contrast to the nitrogen-codoped counterpart that put up considerably intense OP. The heavily P doping is believed to exert a significant enhancement effect on oxygen precipitate nucleation at 650 deg C but not at 750 and 850 deg C, while the nitrogen codoping offers heterogeneous centers for oxygen precipitate nucleation at 750 or 850 deg C. It is reasonably believed that nitrogen codoping is also an effective pathway to enhance oxygen precipitation in heavily P-doped CZ-Si.