Patent ID: 7400411
Filing Date: 2008-07-15
Classification: G01B,G01N,H01L

Abstract:
1. A method for optically testing semiconductor devices or wafers while being manufactured, the device or wafer under test being comprised of a semiconductor material having an exterior surface and interior structures, comprising: using a holographic optical interference system with at least one light source providing a light beam of coherent wavelength with a wavelength to which the semiconductor material is transparent, splitting the light beam into a pair of beams comprising of a reference beam and an object beam, imposing the object beam on the exterior surface of the semiconductor material to generate a reflected object beam reflected from the interior structures of the semiconductor material, adjusting the angle of the reference beam relative to the object beam between a plurality of angles with the semiconductor material being in a different state for each angle of the reference beam, imposing the reflected object beam and the reference beam onto a detection device to create a plurality of interference patterns of the reflected object beam with the reference beam, one at each of the plurality of angles of the reference beam, and comparing the plurality of interference patterns to one another to determine characteristics within the semiconductor material.