Study of thermal behaviour of oxygen in silicon crystals by analysis of X-ray Pendellösung fringes

The thermal behaviour of oxygen in Czochralski (CZ) silicon and magnetic Czochralski (MCZ) silicon crystals was investigated by analysis of Pendellösung sung fringes based on the statistical theory of X-ray dynamical diffraction. The size and the density of oxygen precipitates were determined for different annealing temperatures and/or different times. It was observed that oxide precipitates in the samples increase in size and decrease in density with time during isothermal annealing at 1023 K. The precipitation in MCZ silicon approaches saturation level after annealing for 250 h. It was found that the size of precipitates increases rapidly with annealing temperature in isochronal annealing for 18 h. Comparison of the results of MCZ silicons with those of CZ silicons shows that MCZ crystals are thermally more stable. This suggests that magnetic fields can control the oxygen concentration effectively and that the MCZ and CZ silicon have different thermal behaviours. A powerful technique for detecting microdefects of nanometre size and random distribution is described.