Pattern matching method and pattern matching apparatus
View Patent ↗Provided is a template matching method and a template matching apparatus, where the degree of matching between a template and the actual image upon template matching is maintained at a high level, without depending on a partial appearance of a lower layer. Proposed as one embodiment, is a method and an apparatus for template matching, where either an area is set in which comparison of the template and the image is not conducted, or a second area is set inside the template where comparison different from comparison conducted in a first comparison area is to be conducted, and the template matching is conducted on the basis either of comparison excluding the non-comparison area, or of comparison using the first and second areas.
1. A pattern matching method for performing pattern matching on a search-target image of a sample by using a template, comprising the steps of:
defining in the template an excluding area where a first comparison between the template and the image is excluded, or a first comparison area and a second comparison area where a second comparison different from the first comparison is performed, in accordance with a status of the search-target image for each location where the template is positioned while matching is performed using the template so that an edge of a pattern in the template is excluded from the excluding area or the first comparison area; and
executing template matching based on comparison processing excluding the excluding area or comparison processing in the first and second comparison areas.
2. A pattern matching method according to claim 1 , wherein a lower layer pattern exists in a position of a sample specified by pattern matching and under a position corresponding to the excluding area or the first comparison area.
3. A pattern matching method according to claim 2 , wherein the excluding area or the first comparison area is defined to comprise an area having a possibility that the lower layer pattern appears in the search-target image.
4. A pattern matching method according to claim 1 , wherein an area other than an area along a pattern edge of the template is defined as the excluding area or the first comparison area.
5. A pattern matching method according to claim 1 , wherein an area along a pattern edge of the template is selectively defined as an area subjected to comparison processing.
6. A pattern matching method according to claim 1 , further comprising the step of performing a correlation operation between the search-target image and the template, wherein an area having a correlation value due to the correlation operation smaller than or equal to a predetermined value is defined as the excluding area or the first comparison area while an area having the correlation value greater than the predetermined value is defined as an area subjected to comparison processing or the second comparison area.
7. A pattern matching method according to claim 1 , wherein the step of executing template matching further comprises the steps of:
performing a coarse-to-fine search;
setting the excluding area using a template for coarse search in a coarse search; and
setting the excluding area using a template for fine search in a fine search.
8. A pattern matching apparatus for performing pattern matching on a search-target image of a sample using a template comprising:
an arithmetic unit defining in the template an excluding area, in the excluding area comparison of the template and the image being excluded, or in the template a first comparison area and a second comparison area, in the second comparison area comparison different from one in the first comparison area being performed, in accordance with a status of the search-target image for each location where the template is positioned while matching is performed using the template so that an edge of a pattern in the template is excluded from the excluding area or the first comparison area; and performing template matching based on comparison processing excluding the excluding area, or based on comparison processing in the first and second comparison areas.
9. A pattern matching apparatus according to claim 8 , wherein the arithmetic unit defines the excluding area or the first comparison area in an area where a lower layer pattern of the sample is located.
10. A pattern matching apparatus according to claim 9 , wherein the area where the lower layer pattern of the sample is located comprises an area having a possibility that the lower layer pattern appears in the search-target image.
11. A pattern matching apparatus according to claim 8 , wherein the arithmetic unit defines an area other than an area along a pattern edge of the template as the excluding area or the first comparison area.
12. A pattern matching apparatus according to claim 8 , wherein the arithmetic unit defines selectively an area along a pattern edge of the template as an area subjected to comparison processing.
13. A pattern matching apparatus according to claim 8 , wherein the arithmetic unit performs correlation operation between the search-target image and the template; and defines an area having a correlation value due to the correlation operation smaller than or equal to a predetermined value as the excluding area or the first comparison area and an area having the correlation value greater than the predetermined value as an area subjected to comparison processing or the second comparison area.
14. A pattern matching apparatus according to claim 8 , wherein the arithmetic unit performs a coarse-to-fine search when the template matching is executed; defines the excluding area using a template for coarse search in a coarse search; and defines the excluding area using a template for fine search in a fine search.
15. A non-transitory computer readable medium having a computer program for making a computer connected to an image acquisition apparatus specify a position of a pattern on an image based on matching between the pattern on the image formed by the image acquisition apparatus and a template, the program defining in the template an excluding area, in the excluding area comparison of the template and the image being excluded, or in the template a first comparison area and a second comparison area, in the second comparison area comparison different from one in the first comparison area being executed, in accordance with a status of the search-target image for each location where the template is positioned while matching is performed using the template so that an edge of a pattern in the template is excluded from the excluding area or the first comparison area; and performing template matching based on comparison processing excluding the excluding area, or comparison processing in the first and second comparison areas.
16. The non-transitory computer readable medium having the computer program according to claim 15 , wherein a lower layer pattern exists in a position of a sample specified by pattern matching and under a position corresponding to the excluding area or the first comparison area.
17. The non-transitory computer readable medium having the computer program according to claim 16 , wherein the excluding area or the first comparison area is defined to comprise an area having a possibility that the lower layer pattern appears in the search-target image.
18. The non-transitory computer readable medium having the computer program according to claim 15 , further defining an area other than an area along a pattern edge of the template as the excluding area or the first comparison area.
19. The non-transitory computer readable medium having the computer program according to claim 15 , further defining an area along a pattern edge of the template selectively as an area subjected to comparison processing.