Detection of very small defects and tiny inclusions just under mirror polished surfaces of silicon wafers by inside total reflection

Abstract

Defects just beneath the mirror surface of a silicon wafer grown by the Czochralski method is critical for epitaxial growth on the surface. Inside total reflection of an IR laser beam allowed only the light scattered by defects and tiny inclusions in the denuded zone of the wafer to be observed through the surface, because part of the scattered light makes an incident angle smaller than the critical one while the unscattered part of the beam is totally reflected and thus does not emerge from the wafer. Background brightness was caused by light scattering from tiny inclusions such as interstitial oxygen atoms in the zone, and inhomogeneity of this background indicated distribution fluctuation of the defects with gettering function.