The invention discloses an
overlay mark center positioning method and a related device, and relates to the technical field of
chip manufacturing, and the method comprises the steps: determining an approximate position of an
overlay mark through employing a preset
region of interest, carrying out the gray projection of an
overlay mark image in a horizontal direction and a vertical direction in the preset
region of interest, generating a one-dimensional gray curve, and carrying out the positioning of the center of the overlay mark. Two-dimensional information of an overlay mark image is reduced to one-dimensional information, the calculation data volume is effectively reduced, then a target curve is obtained by performing
noise reduction
processing on a one-dimensional gray curve,
noise interference is reduced, accuracy and effectiveness of overlay mark center positioning are guaranteed, and finally, the overlay mark center positioning accuracy and effectiveness are improved by utilizing the priori knowledge that the overlay mark is symmetrical in the horizontal direction and the vertical direction. And calculating the symmetric length of each point in the target search range of the target curve to obtain a symmetric curve formed by the symmetric lengths of the points, and determining the
peak value of the symmetric curve as the overlay mark center to ensure the accuracy and reliability of the overlay mark center.