Patent ID: 8823935

Claim:
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 the first beam and the second beam are directed onto the surface of the substrate simultaneously, the first radiation targeting assembly is separate from the second radiation targeting assembly, and the first peak wavelength is different from the second peak wavelength, 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, first scattered radiation through the third aperture, second scattered radiation through the third aperture, and first and second scattered radiation through the third aperture, and produce fourth signals, 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, record the first, second, third, and fourth signals, and analyze the first, second, third, and fourth signals to detect and classify defects on the surface of the substrate.