Coexistence of Two Types of Nucleation Sites for Oxygen Precipitates in Czochralski Silicon

We have found that the nuclei effective for annealing at 800°C are dominantly generated at two characteristic temperatures of 500°C and 650°C. Carbon-related oxygen aggregates, whose density increases with increasing carbon concentration, are generated at temperatures around 500°C. Thermal-donor-related oxygen aggregates which thermal donors grow into are additionally created at temperatures around 500°C. In low-carbon-content silicon, thermal-donor-related oxygen aggregates are dominantly created at 500°C. Another type of carbon-related oxygen aggregate is generated at temperatures around 650°C. The rapid nucleation in high-carbon-content silicon during annealing at 500°C for only 30 min is reasonably explained by considering that carbon-related oxygen aggregates formed at about 500°C are composed of Ci-O2complexes.