Multiple-scan method for wafer particle analysis
Patent 5422724 Issued on June 6, 1995. Estimated Expiration Date: 
August 31, 2013. 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.
August 31, 2013. 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 ReferencesOptical inspection system for semiconductor wafers Patent #: 4659220 InventorsApplicationNo. 116232 filed on 08/31/1993US Classes:356/615, Position transverse to viewing axis257/E21.525, Procedures, i.e., sequence of activities consisting of plurality of measurement and correction, marking or sorting steps (EPO)257/E21.53, For structural parameters, e.g., thickness, line width, refractive index, temperature, warp, bond strength, defects, optical inspection, electrical measurement of structural dimensions, metallurgic measurement of diffusions (EPO)356/72, WITH PLURAL DIVERSE TEST OR ART356/237.3Detection of object or particle on surfaceExaminersPrimary: Evans, F. L.Attorney, Agent or FirmInternational ClassG01B 011/00AbstractA method for reducing targeting errors encountered when trying to locate contaminant particles in a high-magnification imaging device, based on estimates of the particle positions obtained from a scanning device. The method of the invention includes scanning a semiconductor wafer in a scanning device, then preferably moving the wafer to a different orientation, and scanning the wafer again, to obtain at least two sets of particle coordinates that may differ slightly because of uncertainties in the scanning process. The multiple sets of coordinates are averaged to reduce the targeting errors, but only after transforming the coordinates to a common coordinate system. The transformation step includes computing transformation parameters for each possible pair of particles detected in at least two scans, averaging the results, and then transforming all of the particle coordinates to the common coordinate system. Optionally, the method may include discarding any transformation parameters that deviate too far from the average, and then computing the average transformation parameters again. | |
