Radiant energy – Inspection of solids or liquids by charged particles – Methods
Patent
1996-02-23
1997-08-19
Nguyen, Kiet T.
Radiant energy
Inspection of solids or liquids by charged particles
Methods
250310, 382145, H01J 3700
Patent
active
056591721
ABSTRACT:
A method for fast and reliable defect detection on semiconductor devices by comparing SEM images from a single perspective followed by a cross-check between at least two perspectives. An SEM equipped with at least two electron detectors each of which is capable of collecting electrons from different angular sectors. `Base` images of an area of the semiconductor wafer which is to be inspected are generated from both perspectives. For each perspective base image, a perspective `reference` image is generated, which is suitable for comparison with the base image. The reference image is registered with respect to the base image, for each perspective, the reference image is compared with the base image, and a comparison map of possible defect locations is produced, and, finally, a cross-check is carried out between the perspective comparison maps. The cross-check filters out events in the perspective comparison maps relating to variations other than defects such as pattern variations and noise.
REFERENCES:
patent: 4460827 (1984-07-01), Onoguchi et al.
patent: 4794646 (1988-12-01), Takeuchi et al.
patent: 4805123 (1989-02-01), Specht et al.
Dotan Noam
Wagner Mark
Friedman Mark M.
Nguyen Kiet T.
Opal Technologies Ltd.
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