System for automatic inspection of periodic patterns

Details System for automatic inspection of periodic patterns System for automatic inspection of periodic patterns

1988-05-16

1990-11-06

Boudreau, Leo H.

Image analysis

Histogram processing

For setting a threshold

382 27, 382 50, G06K 900

Patent

active

049691988

ABSTRACT:
A method and apparatus for automatic inspection of periodic patterns typically found on patterned silicon wafers, printed circuit board, and the like is disclosed herein. The method comprises an inspection algorithm of two parts: a low-level algorithm and a higher level algorithm. The low-level algorithm utilizes the known periodically of the pattern to find defects by comparing identical cells in the periodic array. The high-level algorithm applies the low-level algorithm, some number of times (N) in succession on the image; accumulates defective pixels to form a separate image; and then applies a threshold-sort operation on a neighborhood to determine center pixel defectiveness.
The apparatus for implementing the above method comprises a parallel/pipeline architecture for high speed processing and RAM LUT's to implement a plurality of subtract and compare functions.

REFERENCES:
patent: 4047152 (1977-09-01), Giuliano
patent: 4428672 (1984-01-01), Allard et al.
patent: 4448532 (1984-05-01), Joseph et al.
patent: 4463373 (1984-07-01), Mikami
patent: 4532650 (1985-07-01), Wihl et al.
patent: 4628531 (1986-12-01), Okamoto

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