Patent ID: 8823935
Filing Date: 2014-09-02
Classification: G01N

Abstract:
1. An apparatus to detect and classify defects on a surface of a substrate, comprising: an ellipsoid of revolution disposed over the substrate, having first and second open ends with first and second loci at the first and second open ends respectively, a reflective interior, and separate first, second, and third apertures, a first radiation targeting assembly to direct first radiation having a first peak wavelength in a first beam along a first path between the ellipsoid of revolution and the substrate and onto the surface of the substrate at the position of the first locus, thereby forming a specularly reflected first beam that leaves the surface of the substrate along a path between the ellipsoid of revolution and the substrate, and also forming scattered first radiation that is reflected by the ellipsoid of revolution to the second locus, a second radiation targeting assembly to direct second radiation having a second peak wavelength in a second beam along a second path through the first aperture in the ellipsoid of revolution and onto the surface of the substrate at the position of the first locus, thereby forming a specularly reflected second beam that leaves the surface of the substrate along a path through the second aperture of the ellipsoid of revolution, and also forming scattered second radiation that is reflected by the ellipsoid of revolution to the second locus, where a first radiation collecting assembly to collect the specularly reflected first beam and produce first signals, a second radiation collecting assembly to collect first radiation from the second locus and produce second signals, a third radiation collecting assembly to collect second radiation from the second locus and produce third signals, a fourth radiation collecting assembly to selectively collect one of, a processor coupled to the first, second, third, and fourth radiation collecting assemblies, for receiving the first, second, third, and fourth signals, a memory module coupled to the processor and comprising logic instructions stored in a computer-readable storage medium, which when executed by the processor configure the processor to,