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US 7,466,854 B2Granted
Size checking method and apparatus
AssigneeKabushiki Kaisha Toshiba
InventorsEiji Sawa, Hiromu Inoue
Life of this patent
Estimating the term…
Abstract
A pair of edges that are located at ends as viewed in the widthwise direction of a design pattern are recognized. On the basis of the edge direction in which the paired edges are recognized, edge points on the design pattern are detected as sub-pixels. The widthwise dimension of the design pattern is calculated on the basis of the edge points. In addition, the widthwise dimension of a circuit pattern is calculated at the same position as the widthwise dimension of the design pattern. On the basis of the calculated widthwise dimensions, the semiconductor wafer circuit pattern is checked.
Claims14
A size checking method comprising:
- a first step of reading image data on a reference pattern and recognizing an edge direction of the reference pattern on the basis of pixel values detected at edge portions which are end portions as viewed in a width direction of the reference pattern;
- a second step of detecting edge points corresponding to the end portions as sub-pixels on the basis of the pixel values detected at the edge portions, and calculating a widthwise dimension of the reference pattern from the edge points;
- a third step of acquiring image data on a pattern under inspection;
- a fourth step of detecting edge points at each of edge portions which are end portions as viewed in a width direction of the pattern under inspection, said edge points of the pattern under inspection being detected with respect to edge portions located at the same position as the edge portions whose widthwise dimension is calculated by use of the reference pattern, and of calculating the widthwise dimension of the pattern under inspection, said edge points of the pattern under inspection as starting points;
- a fifth step of determining whether or not the pattern under inspection is defective on the basis of the widthwise dimension of the reference pattern and the widthwise dimension of the pattern under inspection;
- a sixth step of preparing a frequency distribution with respect to a dimensional error obtained on the basis of the widthwise dimension of the reference pattern and the widthwise dimension of the pattern under inspection, and varying a threshold value used in the second step when the edge points are detected as sub-pixels;
- said fifth step including,
- calculating a dimensional error on the basis of the difference between the widthwise dimension of the pattern under inspection and the widthwise dimension of the reference pattern, and
- determining an abnormal state when a value obtained by adding an offset value to the dimensional error is out of an allowable range;
- and
- said sixth step including,
- preparing a frequency distribution with respect to the dimensional error, which is based on both the widthwise dimension of the pattern under inspection and the widthwise dimension of the reference pattern, and
- varying the offset value or a threshold value which is that of either the reference pattern or the pattern under inspection, and which used in the second step when the edge points are detected as sub-pixels, on the basis of the frequency distribution;
- the first step including,
- scanning a measurement window across the reference pattern,
- detecting edge directions of the reference pattern,
- making a search in different directions from a pixel of interest which is located inside an area of the measurement window, said different directions being an X direction, a Y direction orthogonal to the X direction, directions which form angles of ±45° with reference to the X and Y directions, and
- examining edge directions in the vicinity of the edge portions of the reference pattern on the basis of the directions in which the search is carried out, and recognizing a pair when templates of edge direction patterns show that the edge directions oppose each other.
15 more elements
A size checking method comprising:
- a first step of reading image data on a reference pattern and recognizing an edge direction of the reference pattern on the basis of pixel values detected at edge portions which are end portions as viewed in a width direction of the reference pattern;
- a second step of detecting edge points corresponding to the end portions as sub-pixels on the basis of the pixel values detected at the edge portions, and calculating a widthwise dimension of the reference pattern from the edge points;
- a third step of acquiring image data on a pattern under inspection;
- a fourth step of detecting edge points at each of edge portions which are end portions as viewed in a width direction of the pattern under inspection, said edge points of the pattern under inspection being detected with respect to edge portions located at the same position as the edge portions whose widthwise dimension is calculated by use of the reference pattern, and of calculating the widthwise dimension of the pattern under inspection, said edge points of the pattern under inspection as starting points;
- a fifth step of determining whether or not the pattern under inspection is defective on the basis of the widthwise dimension of the reference pattern and the widthwise dimension of the pattern under inspection;
- a sixth step of preparing a frequency distribution with respect to a dimensional error obtained on the basis of the widthwise dimension of the reference pattern and the widthwise dimension of the pattern under inspection, and varying a threshold value used in the second step when the edge points are detected as sub-pixels;
- said fifth step including,
- calculating a dimensional error on the basis of the difference between the widthwise dimension of the pattern under inspection and the widthwise dimension of the reference pattern, and
- determining an abnormal state when a value obtained by adding an offset value to the dimensional error is out of an allowable range;
- and
- said sixth step including,
- preparing a frequency distribution with respect to the dimensional error, which is based on both the widthwise dimension of the pattern under inspection and the widthwise dimension of the reference pattern, and
- varying the offset value or a threshold value which is that of either the reference pattern or the pattern under inspection, and which used in the second step when the edge points are detected as sub-pixels, on the basis of the frequency distribution;
- the first step including,
- scanning a measurement window across the reference pattern,
- detecting an edge direction of the reference pattern,
- making a search in different directions from a pixel of interest which is located inside an area of the measurement window, said different directions being an X direction, a Y direction orthogonal to the X direction, directions which form angles of ±45° with reference to the X and Y directions, directions of bisectors between each of these directions and the X and Y directions, and
- examining edge directions in the vicinity of the edge portions of the reference pattern on the basis of the directions in which the search is carried out, and recognizing a pair when templates of edge direction patterns show that the edge directions oppose each other.
15 more elements
A size checking apparatus comprising:
- pattern recognition means for reading image data on a reference pattern and recognizing an edge direction of the reference pattern on the basis of pixel values detected at edge portions which are end portions as viewed in a width direction of the reference pattern;
- first size-measuring means for detecting edge points corresponding to the end portions as sub-pixels on the basis of the pixel values detected at the edge portions, and for calculating a widthwise dimension of the reference pattern, from the edge points as starting points;
- means for acquiring image data on a pattern under inspection;
- second size-measuring means for reading the image data on the pattern under inspection and for calculating a widthwise dimension of the pattern under inspection, from edge portions located at the same position as the edge portion whose widthwise dimension is calculated by use of the reference pattern;
- and
- means for determining whether or not the pattern under inspection is defective on the basis of the widthwise dimension of the reference pattern and the widthwise dimension of the pattern under inspection;
- threshold value-varying means for preparing a frequency distribution with respect to a dimensional error of the reference pattern and for varying a threshold value which the first size-measuring means uses when the edge points are detected as sub-pixels, on the basis of the frequency distribution;
- dimensional error determination means comprising,
- means for calculating the dimensional error on the basis of the difference between the widthwise dimension of the pattern under inspection and the widthwise dimension of the reference pattern, and
- means for determining an abnormal state when a value obtained by adding an offset value to the dimensional error is out of an allowable range;
- said pattern recognition means including,
- means for scanning a measurement window across the reference pattern,
- means for detecting an edge direction of the reference pattern,
- means for making a search in different directions from a pixel of interest which is located inside an area of the measurement window, said different directions being an X direction, a Y direction orthogonal to the X direction, directions which form angles of ±45° with reference to the X and Y directions, and
- means for examining edge directions in the vicinity of the edge portions of the reference pattern on the basis of the directions in which the search is carried out, and for recognizing a pair when templates of edge direction patterns show that the edge directions oppose each other.
12 more elements
A size checking apparatus comprising:
- pattern recognition means for reading image data on a reference pattern and recognizing an edge direction of the reference pattern on the basis of pixel values detected at edge portions which are end portions as viewed in a width direction of the reference pattern;
- first size-measuring means for detecting edge points corresponding to the end portions as sub-pixels on the basis of the pixel values detected at the edge portions, and for calculating a widthwise dimension of the reference pattern, from the edge points as starting points;
- means for acquiring image data on a pattern under inspection;
- second size-measuring means for reading the image data on the pattern under inspection and for calculating a widthwise dimension of the pattern under inspection, from edge portions located at the same position as the edge portion whose widthwise dimension is calculated by use of the reference pattern;
- and
- means for determining whether or not the pattern under inspection is defective on the basis of the widthwise dimension of the reference pattern and the widthwise dimension of the pattern under inspection;
- threshold value-varying means for preparing a frequency distribution with respect to a dimensional error of the reference pattern and for varying a threshold value which the first size-measuring means uses when the edge points are detected as sub-pixels, on the basis of the frequency distribution;
- dimensional error determination means comprising,
- means for calculating the dimensional error on the basis of the difference between the widthwise dimension of the pattern under inspection and the widthwise dimension of the reference pattern, and
- means for determining an abnormal state when a value obtained by adding an offset value to the dimensional error is out of an allowable range;
- said pattern recognition means including,
- means for scanning a measurement window across the reference pattern,
- means for detecting an edge direction of the reference pattern,
- means for making a search in different directions from a pixel of interest which is located inside an area of the measurement window, said different directions being an X direction, a Y direction orthogonal to the X direction, directions which form angles of ±45° with reference to the X and Y directions, directions of bisectors between each of these directions and the X and Y directions, and
- means for examining edge directions in the vicinity of the edge portions of the reference pattern on the basis of the directions in which the search is carried out, and for recognizing a pair when templates of edge direction patterns show that the edge directions oppose each other.
12 more elements
Dependencies are inferred from the claim text.