Patent ID: 8148176
Filing Date: 2012-04-03
Classification: G01J,G01N,H01L

Abstract:
1. A method of distinguishing a set of highly doped regions from a set of lightly doped regions on a silicon substrate, comprising: providing the silicon substrate, the silicon substrate configured with the set of lightly doped regions and the set of highly doped regions, the substrate further having a first surface and a second surface; illuminating the first surface with an electromagnetic radiation from a source, the electromagnetic radiation having a wavelength above 1100 nm; and, measuring the electromagnetic radiation transmitted through the substrate with a sensor on the second surface in order to determine an absorption of a region of the set, wherein for any wavelength above 1100 nm, the measured absorption of the wavelength in the lightly doped regions is substantially less than the measured absorption of the wavelength in the heavily doped regions.