PURPOSE: To accurately detect a mark position without being affected by the condition of the surface of an alignment mark prepared on a substrate by detecting the minimum one of configurations similar to a predetermined configuration at least partly in contact with the positioning mark obtained from a binary image signal and by using the position of the detected minimum configuration to detect the position of the positioning mark.
CONSTITUTION: A pattern is detected (reference number 40), encoded into a binary value (reference number 41), and converted into a two dimensional binary digital image, followed by detecting the outermost border line of the pattern (reference number 42), further followed by obtaining summits of a totally convex polygon from a group of points composing the outermost border line (reference number 43), furthermore followed by obtaining the farmost point Voronoi-diagram for the summits of the totally convex polygon (reference number 44), again followed by obtaining a circle with the minimum radius from circles having the center at the Voronoi point and passing the three points corresponding to three Voronoi areas adjacent to the Voronoi points, that is, the minimum inclusive circle (reference number 45), and finally followed by letting the center of this minimum inclusive circle be the position of positioning mark. The minimum inclusive circle can be determined at a constant position despite a defect of the profile section, thereby being able to detect the position of the substrate accurately. With this, the position of a substrate can be accurately detected. Since the inclusive configurations have only to be circum-scribed about the positioning mark, they have only to be made similar to one another.
HAMADA TOSHIMITSU
NAKAGAWA YASUO
| JPH02137338A | 1990-05-25 | |||
| JPS63101972A | 1988-05-06 |