Pattern inspection apparatus, pattern inspection method, and recording medium
First, a pattern inspection apparatus detects the first edge from an image of a pattern to-be-inspected. Next, the pattern inspection apparatus conducts matching of the image of the pattern to-be-inspected and the first reference pattern by comparing the first edge and an edge of the first reference pattern. Since, as a result of the matching, a shift quantity S 1 can be obtained, and then the first reference pattern is shifted by this shift quantity S 1 . Subsequently the pattern to-be-inspected is inspected by comparing the first edge and the edge of the first reference pattern so shifted. In this first inspection, pattern deformation quantities are obtained and defects are detected. A shift quantity S 2 can be obtained as one of the pattern deformation quantities. Next, in order to detect the second edge from the pattern image to-be-inspected, the corresponding second reference pattern is shifted by a shift quantity S 1 +S 2 . Using the second reference pattern so shifted, a profile is obtained on the pattern image to-be-inspected and the second edge is detected. Then, by comparing the second edge and the edge of the second reference pattern so shifted, the pattern to-be-inspected is inspected. Also in this second inspection, the pattern deformation quantities are obtained and defects are detected. A shift quantity S 3 can be obtained as one of the pattern deformation quantities.
1. A pattern inspection apparatus for inspecting a pattern to-be-inspected by comparing an image of said pattern to-be-inspected with a reference pattern obtained from design data, said pattern inspection apparatus comprising:
storage means for storing said reference pattern;
inputting means for inputting said pattern image to-be-inspected;
detecting means for detecting an edge of said pattern image to be-inspected;
inspecting means for inspecting said pattern to-be-inspected by comparing the edge of said pattern image to-be-inspected and an edge of said reference pattern;
outputting means for outputting a result of said inspection; and
means for converting said design data into said reference pattern by correcting said design data with respect to a deformation which may occur in said pattern to-be-inspected.
2. The pattern inspection apparatus as claimed in claim 1 , wherein said detecting means detects the edge of said pattern image to-be-inspected with a sub pixel accuracy.
3. The pattern inspection apparatus as claimed in claim 1 , wherein said inspecting means assumes the correspondence of the edge of each pixel of said reference pattern to the edge of each pixel of said pattern image to-be-inspected.
4. The pattern inspection apparatus as claimed in claim 3 , wherein said correspondence-assumption is conducted considering the distance between the edge of each pixel of said reference pattern and the edge of each pixel of said pattern image to-be-inspected and the directional difference between both the edges.
5. The pattern inspection apparatus as claimed in claim 3 , wherein said inspecting means constructs an area based on the edges of said pattern image to-be-inspected in which said inspecting means failed to assume said correspondence to the edges of said reference pattern, and recognizes said area as a defective area.
6. The pattern inspection apparatus as claimed in claim 3 , wherein said inspecting means constructs an area based on the edges of said pattern image to be-inspected in which said inspecting means succeeded in assuming said correspondence to the edges of said reference pattern, detects an area whose luminance distribution is non-uniform among the areas, and determines said area as a defective area.
7. The pattern inspection apparatus as claimed in claim 5 or 6 , wherein said inspecting means judges a defect class based on geometrical feature quantities of said defective area.
8. The pattern inspection apparatus as claimed in claim 5 or 6 , wherein said inspecting means judges a defect class based on a feature quantity concerning the luminance of said defective area.
9. The pattern inspection apparatus as claimed in claim 3 , wherein said inspecting means calculates a pattern deformation quantity or pattern deformation quantities of said pattern to-be-inspected with respect to said reference pattern.
10. The pattern inspection apparatus as claimed in claim 9 , wherein said pattern deformation quantity includes at least one of a displacement quantity, a magnification variation quantity, and a dilation quantity of the line width.
11. The pattern inspection apparatus as claimed in claim 9 , wherein said inspecting means adds an attribute of the pattern to said reference pattern.
12. The pattern inspection apparatus as claimed in claim 1 , wherein said inspecting means forms a profile by examining luminance values in a profile acquisition section in said pattern image to-be-inspected, detects predetermined points for each said profile, approximates the detected points with a curve, and assumes the curve to be an edge of said pattern image to-be-inspected.
13. A pattern inspection apparatus for inspecting a pattern to-be-inspected by comparing an image of said pattern to-be-inspected with a reference pattern obtained from design data, said pattern inspection apparatus comprising:
storage means for storing said reference pattern;
inputting means for inputting said pattern image to-be-inspected;
inspecting means for inspecting said pattern to-be-inspected by comparing an edge of said pattern image to-be-inspected and an edge of said reference pattern; and
outputting means for outputting a result of said inspection,
wherein said inspecting means conducts matching between said pattern image to-be-inspected and said reference pattern by comparing the edge of said pattern image to-be-inspected and the edge of said reference pattern; and
means for converting said design data into said reference pattern by correcting said design data with respect to a deformation which may occur in said pattern to-be-inspected.
14. The pattern inspection apparatus as claimed in claim 13 , wherein said matching is conducted by dilating the edge of said pattern image to-be-inspected or the edge of said reference pattern.
15. The pattern inspection apparatus as claimed in claim 14 , wherein said matching is conducted by dilating the edge of said pattern image to-be-inspected or the edge of said reference pattern with weightings given.
16. The pattern inspection apparatus as claimed in claim 13 , wherein said matching is conducted by using the total sum of products of amplitudes of the edges of said pattern image to-be-inspected and amplitudes of the edges of said reference pattern at respective pixels as an evaluation value.
17. The pattern inspection apparatus as claimed in claim 13 , wherein said matching is conducted by calculating an evaluation value of the matching in consideration of a direction of the edge of said pattern image to-be-inspected and a direction of the edge of said reference pattern.
18. The pattern inspection apparatus as claimed in claim 17 , wherein said matching is conducted by using the total sum of inner products of edge vectors of said pattern image to-be-inspected and edge vectors of said reference pattern at respective pixels or the total sum of absolute values of said inner products as an evaluation value, wherein each of said edge vectors has a magnitude equal to amplitude of the edge and a direction identical to the direction of the edge.
19. The pattern inspection apparatus as claimed in claim 13 , wherein said matching is conducted by altering for each part of said reference pattern, a contribution thereof to the matching.
20. The pattern inspection apparatus as claimed in claim 19 , wherein said matching is conducted by extracting a unique pattern by using periodicity of said reference pattern, and setting different weightings for an evaluation value of the matching depending on whether a pattern in said reference pattern is the unique pattern or not.
21. The pattern inspection apparatus as claimed in claim 1 , or 13 , further comprising means for setting allowable pattern deformation quantity and/or allowable pattern directional difference with respect to said reference pattern.
22. The pattern inspection apparatus as claimed in claim 21 , wherein allowable pattern deformation quantity and/or said allowable pattern directional difference can be set individually in accordance with an attribute of said reference pattern.