Various micro-crystalline defects in monocrystals, such as flow pattern defects, crystal-originated particles and laser scattering tomographic defects, were studied. It was suggested that flow pattern defects and crystal-originated particles were due to the same crystal defects which were generated during crystal growth. This was because those defects were not influenced by the interstitial O or substitutional C concentration, and closely resembled each other with regard to their generation and annihilation behaviors. On the other hand, the laser scattering tomographic defects were related to O precipitates. The D defects comprised a plurality of crystal defects such as flow pattern defects, crystal-originated particles and laser scattering tomographic defects. After oxidation at 1473K, gate oxide integrity recovered by 50 to 80% in Czochralski wafers and by up to 100% in N non-doped float-zone wafers. The flow pattern defects and crystal-originated particles seemed to be completely annihilated after such treatments, while the laser scattering tomographic defects were insufficiently annihilated. The gate oxide integrity of Czochralski wafers recovered by up to 100%, upon annealing in a H ambient, because laser scattering tomographic defects in the vicinity of the wafer surface were also annihilated.

I.Fusegawa, K.Takano, M.Kimura, N.Fujimaki: Materials Science Forum, 1995, 196-201, 1683-90