Abstract: A silicon wafer characterized in that the laser scattering tomography defect occurrence region accounts for at least 80% of the wafer surface area and that the laser scattering tomography defects have a mean size of not more than 0.1 &mgr;m, with the density of those defects which exceed 0.1 &mgr;m in size being not more than 1×105 cm−3, and wafers derived from this wafer as the raw material by heat treatment for oxide precipitate formation, by heat treatment for denuded layer formation or by epitaxial layer formation on the surface are useful as semiconductor materials.