Optics: measuring and testing – By polarized light examination – With light attenuation
Patent
1993-08-31
1995-06-06
Evans, F. L.
Optics: measuring and testing
By polarized light examination
With light attenuation
356 72, 356237, G01B 1100
Patent
active
054227240
ABSTRACT:
A 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.
REFERENCES:
patent: 4659220 (1987-04-01), Bronte et al.
Kinney Patrick D.
Lee Harry Q.
Uritsky Yuri S.
Applied Materials Inc.
Evans F. L.
Heal Noel F.
Sgarbossa Peter J.
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