Enhancement of oxygen precipitation in quenched Czochralski silicon crystals

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Abstract
The effect of cooling rates from solution annealing (>1270 °C) on oxygen precipitation in Czochralski silicon crystals was studied. The higher the cooling rate, the more oxygen precipitated. There was a lot of oxygen precipitation in quenched silicon after solution annealing, but not much in quenched silicon after solution annealing followed by solution annealing and then slow cooling. When slowly cooled silicon is quenched after solution annealing, the amount of oxygen precipitation was large again. This indicates that quenching from high temperature introduces defects which enhance oxygen precipitation. We assume that the defects are related to intrinsic point defects. We found that these defects disappear above 900 °C. Nitrogen impurities diffused into silicon during high-temperature annealing also enhance oxygen precipitation.