Effect of Grown-in Defects on the Structure of Oxygen Precipitates in Cz-Si Crystals with Different Diameter

摘要

IR-spectroscopy with computer analysis of the shape of the Si-O absorption band, electron microscopy, X-rays diffraction and measurements of unsteady photoconductivity time-decay under band-to band excitation were used to investigate the influence of defects in different diameter (40 - 300 mm) Si ingots on the oxygen precipitation due to two-stage annealing (750 °C+ 1050 °C). It is shown that large size Cz-Si ingots have a relatively low concentration of electrically active micro-defects, containing small (0.06 - 0.1 urn) dislocation loops. During thermal treatments this leads to the formation of a low stressed oxide phase (SiO_2) with an enhanced thermo-stability. The precipitates in small size ingots, however, contain distorted 4-fold rings of SiO_4 tetrahedra.