/n sifu neutron diffraction study of lattice deformation during oxygen precipitation in silicon

We present the first in situ measurement of the evolution of strain fields due to oxygen precipitation in silicon single crystals by means of high-resolution neutron backscattering. The integrated reflecting power R and the lattice parameter variations Ad/d which are directly related to the strain fields have been measured as a function of temperature and annealing time. In the temperature range from 300 to 1185 K, high purity float zone crystals maintain the R-values characteristic for perfect crystals. In contrast, Czochralski-grown crystals which contain on the order of 10” oxygen atoms cm 3 (20 ppm), show a steep increase in reflectivity starting at 1160 K, and which goes through a maximum at 1350 K. At 1456 K, partial annealing occurs with a time constant of several hours.