Particle detector for rough surfaces
Patent 5189481 Issued on February 23, 1993. Estimated Expiration Date: 
July 26, 2011. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
July 26, 2011. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent References 3857637 Defect plotting system Automatic contaminants detection apparatus Semiconductor wafer surface inspection apparatus and method Surface inspection method and apparatus therefor Patent #: 4902131 InventorsAssigneeApplicationNo. 736517 filed on 07/26/1991US Classes:356/73, PLURAL TEST250/559.41, With foreign particle discrimination circuitry356/237.2Surface conditionExaminersPrimary: McGraw, Vincent P.Attorney, Agent or FirmForeign Patent References
International ClassG01N 021/88AbstractA surface inspection apparatus having multiple inspection stations to inspect a wafer for a number of characteristics. The wafer is placed on a chuck connected to a rack-and-pinion or equivalent system so that the wafer simultaneously rotates and translates under the fixed position of the inspection stations. A single light source may be used by all stations in turn. One station may be a particle detector with collection optics receiving a small select portion of the light scattered from the wafer surface. A second station may be a roughness detector with a collection system to direct a large portion of scattered light to a detector. A position sensitive detector may be used to determine the slope of the wafer surface at an inspection point when the wafer is not clamped to the chuck, giving a measure of surface deformation. These or other stations are positioned about either of two inspection points at which the beam from the light source may be directed. The inspection points are spaced one wafer radius apart to minimize the required wafer motion for a complete surface scan.Other References
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