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We have investigated the formation behavior of grown-in defects in silicon crystals. The void defects are formed by the aggregation of the super-saturated vacancies during the growth process and the V/G parameter (V, growth rate; G, axial temperature gradient at the crystal–melt interface) controls the vacancy concentration. We investigated how the void defects were influenced by V/G and the cooling rate. The density of void defects (Nv) is proportional to the cooling rate (Cr) to the power of 1.5; that is, N v =β C r 1.5 . This relation holds up to a cooling rate of 40 K/min. On the other hand, the coefficient β increases with a decrease in V/G. The relation of N v =β C r 1.5 does not hold for cooling rates >40 K/min, and oxygen precipitation increases instead of void formation. This behavior supports the void formation model of Voronkov. We also discuss this phenomenon in this paper.

Simulations of the point defect diffusion during the crystal growth process are reported for the investigation of the relationship between the distribution of the oxygen precipitation and point defect concentration in CZ silicon crystals. Distribution of the oxygen precipitation is strongly affected by the point defect concentrations during the growth process. There have been many proposed models for the point defect diffusion during the crystal growth process, and the correspondence between point defect concentrations and grown-in defects has been extensively investigated. In this paper, we have compared the distribution of the oxygen precipitation and the ratio of super-saturation between vacancies and self-interstitials. The experimental results agreed with the results obtained by calculation.

The annihilation of grown-in defects by hydrogen annealing have been explained as the dissolution of oxygen precipitates, because it has been generally thought that grown-in defects in Czochralski silicon crystals are gigantic oxygen precipitates. However, it is necessary to re-examine the mechanism of the annihilation of the defects by hydrogen annealing, because recently it has been shown that the grown-in defects were voids of octahedral shape. In this letter, a simulation model is presented which describes the annihilation process of void defects by hydrogen annealing.