Non-destructive diagnostic techniques for oxygen precipitates in Czochralski silicon

This work investigates the determination of oxygen precipitate density in s ilicon using non-destructive methods, based essentially on electrical and o ptical techniques. Regarding electrical techniques, minority carrier diffus ion length measurements by means of surface photo voltage or electrolytical metal tracer methods to determine the density of oxygen precipitates in p- type silicon wafers is evaluated, taking advantage of the activity of oxyge n precipitates as recombination centres for minority carriers. Regarding op tical techniques, the scanning infra-red microscope is considered, which ca n detect oxygen precipitates in silicon exploiting their effectiveness as l ight scattering centres. These techniques are compared with the traditional etching technique, considering samples in a wide range of precipitate dens ity (5 x 10(6)-10(11)cm(-3)) and submitted to a wide variety of thermal tre atments. Correlations are discussed with the support of transmission electr on microscopy, X-ray diffraction and infrared spectroscopy observations, wh ich provide complementary information on size, morphology and matrix stress of the oxygen precipitates. (C) 2001 Elsevier Science Ltd. All rights rese rved.