Patent ID: 9157869
Filing Date: 2015-10-13
Classification: G01N

Abstract:
1. A method for detecting cracks in planar, polycrystalline semiconductor substrates that have two opposite faces and a circumferential edge surface, comprising: directing electromagnetic radiation into the edge surface of the polycrystalline semiconductor substrate, the electromagnetic radiation having a wavelength that is at least partially transmitted by the polycrystalline semiconductor substrate so that the electromagnetic radiation is directed from the edge surface for at least half a distance to a point opposite the edge surface by reflection at the two opposite faces; detecting electromagnetic radiation of at least a portion of one of the two opposite faces with an imaging optical detector that is sensitive to the electromagnetic radiation at the wavelength, wherein the electromagnetic radiation is scattered by the cracks and exits from one of the two opposite faces at sites of the cracks; generating an image of scattering intensity from the electromagnetic radiation detected by the imaging optical detector; and placing an opaque structure between the face of the polycrystalline semiconductor substrate and the imaging optical detector and recognizing a gleaming periphery of the opaque structure as a crack.