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.

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 which includes, therein the operation of the low-level algorithm. The low-level algorithm utilizes the known periodicity of the pattern to find defects by comparing identical cells in the periodic array. The high-level algorithm comprises applying the low-level algorithm, some number of times (N) in succession on the image. An accumulator image is formed by adding the results of the low-level algorithm to create a separate image array where the pixels relate to the number of times that the pixel in the original image was detected as defective by the low-level algorithm.