Effects of low-temperature annealing on oxygen precipitate nucleation in heavily arsenic-doped Czochralski silicon

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Through the comparative investigation on oxygen precipitation behaviors in the heavily and lightly arsenic-doped n-type Czochralski (CZ) silicon wafers subjected to the two-step annealing successively at low temperature (450—800℃) and high temperature (1000℃), the effects of low-temperature annealing on oxygen precipitate nucleation in heavily arsenic-doped CZ silicon wafer have been elucidated. It was found that for the heavily arsenic-doped CZ silicon the oxygen precipitate nucleation during the 450 and 650℃ annealing was more significant than that during the 800℃ annealing, which was contrary to the case for lightly-doped CZ silicon. Moreover, in comparison with the lightly-doped CZ silicon, the oxygen precipitate nucleation at 450 and 650℃ was enhanced while that at 800℃ was suppressed in the heavily arsenic-doped CZ silicon. It is believed that in the heavily arsenic-doped CZ silicon the As-V-O complexes can be formed during the annealing at 450 and 650℃ so as to enhance the oxygen precipitate nucleation; while, during the 800℃ annealing the As-V-O complexes are not stable enough to act as the precursors of nuclei and, moreover, the heavy arsenic-doping leads to compressive lattice stress, therefore the oxygen precipitate nucleation is noticeably suppressed. Furthermore, it is revealed that the nitrogen-doping facilitates the oxygen precipitate nucleation during the annealing at low temperatures especially at 800℃, which is believed to be due to the heterogeneous nucleation centers induced by nitrogen-doping.