DETECTION AND MAPPING OF OXYGEN IN SILICON-WAFERS BY SCANNING INFRARED-ABSORPTION

Scanning Infrared Absorption (S.I.R.A.) setup was carried out for inve stigating and mapping of microdefects distribution in Czochralski sili con wafers. Using CO2 laser, this non destructive, non contact test me thod allows transmitted beam local attenuation from oxygen precipitate s to be determined. Transmitted intensity I-t maps from peak height of the 1080 cm(-1) absorption band were obtained. An inhomogeneous initi al oxygen distribution is found in as-grown samples. The samples were then submitted to preannealing at 750 degrees C for 16 hours, followed by annealing at 900 degrees C for 24 hours. The obtained It fluctuati ons mapping depicts a ring-shaped distribution of oxygen precipitates.