Nickel precipitation in large-diameter Czochralski silicon

摘要

In comparison with small-diameter (4 in), nickel precipitation in large-diameter (8 in) Czochralski silicon (Cz-Si) under air-cooling or slow-cooling was investigated by scanning infrared microscopy (SIRM) and optical microscopy. It was found that a nickel precipitate-free zone with a thickness of 250 mum near the surface formed in the specimen of small-diameter Cz-Si annealed at 1100degreesC under air-cooling, while no nickel precipitates could be observed under slow-cooling. However, nickel precipitates could be found in all the specimens of large-diameter Cz-Si annealed at 11000degreesC despite different cooling rates. These results indicate that nickel precipitation depends not only on the cooling rate but also intrinsic defects or their complexes in Cz-Si. Finally, the mechanism of nickel precipitation in larger-diameter Cz-Si is discussed. (C) 2003 Elsevier B.V. All rights reserved. [References: 25]