Optics: measuring and testing – Inspection of flaws or impurities – Having predetermined light transmission regions
Patent
1996-11-26
1998-09-15
Font, Frank G.
Optics: measuring and testing
Inspection of flaws or impurities
Having predetermined light transmission regions
356369, 25055942, 25055948, G01N 2100
Patent
active
058087354
ABSTRACT:
10A method is described for detecting and characterizing defects on a test surface of a semiconductor wafer. A three-dimensional image of the test surface is aligned and compared with a three-dimensional image of a defect-free reference surface. Intensity differences between corresponding pixels in the two images that exceed a predefined threshold value are deemed defect pixels. According to the method, the pixels of the reference image are grouped according to their respective z values (elevation) to identify different physical layers of the reference surface. Because different surface layers can have different image properties, such as reflectance and image texture, the groups of pixels are analyzed separately to determine an optimal threshold value for each of the groups, and therefore for each layer of the reference surface.
Han Ke
Lee Ken K.
Srinivasan Lakshman
Worster Bruce W.
Font Frank G.
Ratliff Reginald A.
Ultrapointe Corporation
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