Oxygen Precipitation in Heavily Phosphorus-doped Czochralski Silicon

摘要

Oxygen precipitation in heavily phosphorous (P)-doped Czochralski silicon (CZ-Si) subjected to the ramping or two-step anneals was investigated. It was revealed that the grown-in oxygen precipitates have significant effect on oxygen precipitation behaviors during the subsequent annealing, and then resulted in distinctive oxygen precipitation for the wafers form different positions of the ingot. Moreover, it was found that both the seed and tang-end wafers processed significantly intense nucleation at 650 ℃, which was related to phosphorus related precipitates. It was pointed out that with the increase of the annealing temperature, the nucleation rate of oxygen precipitation due to the enhancement of heavily P-doping would gradually weaken but the one due to oxygen clustering became pronounced. Thus, it was understandable that the tang-end wafer annealed at around 750 ℃ processed higher density of oxygen precipitates than the seed-end wafer, while it annealed at 1000 ℃ processed a lower one.