PATTERN EDGE DETECTION METHOD
A method capable of accurately detecting an edge of a pattern on an upper layer and an edge of a pattern on a lower layer is disclosed. The pattern edge detection method includes: generating a sample image of an upper-layer pattern and a lower-layer pattern; applying a first image processing, which is for emphasizing an edge of the upper-layer pattern, to the sample image, thereby generating a first processed image; detecting the edge of the upper-layer pattern based on a brightness profile of the first processed image; applying a second image processing, which is for emphasizing an edge of the lower-layer pattern, to the sample image, thereby generating a second processed image; and detecting the edge of the lower-layer pattern based on a brightness profile of the second processed image.
1 . A pattern edge detection method comprising:
generating a sample image of an upper-layer pattern and a lower-layer pattern;
applying a first image processing, which is for emphasizing an edge of the upper-layer pattern, to the sample image, thereby generating a first processed image;
detecting the edge of the upper-layer pattern based on a brightness profile of the first processed image;
applying a second image processing, which is for emphasizing an edge of the lower-layer pattern, to the sample image, thereby generating a second processed image; and
detecting the edge of the lower-layer pattern based on a brightness profile of the second processed image.
2 . The pattern edge detection method according to claim 1 , wherein:
the first image processing is a tone-curve processing that emphasizes the edge of the upper-layer pattern; and
the second image processing is a tone-curve processing that emphasizes the edge of the lower-layer pattern.
3 . The pattern edge detection method according to claim 2 , wherein:
the tone-curve processing applied to the first image processing is a process of lowering a brightness value at an intermediate level between a brightness value of the upper-layer pattern and a brightness value of the lower-layer pattern; and
the tone-curve processing applied to the second image processing is a process of increasing the brightness value at the intermediate level between the brightness value of the upper-layer pattern and the brightness value of the lower-layer pattern.
4 . The pattern edge detection method according to claim 1 , further comprising:
generating a template image from design data of the upper-layer pattern and the lower-layer pattern, the template image containing a first reference pattern corresponding to the upper-layer pattern and a second reference pattern corresponding to the lower-layer pattern;
aligning the template image and the sample image with each other;
drawing a first perpendicular line on an edge of the first reference pattern; and
drawing a second perpendicular line on an edge of the second reference pattern,
wherein the brightness profile of the first processed image is a distribution of brightness values of the first processed image on the first perpendicular line, and
the brightness profile of the second processed image is a distribution of brightness values of the second processed image on the second perpendicular line.
5 . The pattern edge detection method according to claim 4 , further comprising:
applying a corner-rounding process to the first reference pattern and the second reference pattern.
6 . The pattern edge detection method according to claim 4 , further comprising:
calculating a pattern shift representing a difference between a center of gravity of the upper-layer pattern on the sample image and a center of gravity of the first reference pattern; and
calculating a pattern shift representing a difference between a center of gravity of the lower-layer pattern on the sample image and a center of gravity of the second reference pattern.