Pattern inspection method and pattern inspection apparatus
According to an embodiment, a pattern inspection apparatus includes an imaging unit, a defect detection unit, and an inspection control unit. The imaging unit is configured to image a pattern on a substrate to acquire a pattern image. The defect detection unit is configured to detect a defect of the pattern by a first outer shape comparison in associate with the pattern image and design information for the pattern or by a comparison in pixel values between images of patterns designed to be formed into the same shape in the substrate. The inspection control unit is configured to select an inspection based on the amount of the defect detected by the first outer shape comparison or based on a value of a gradient of an edge profile of the pattern image and to control the imaging unit and the defect detection unit in accordance with the selected inspection.
1. A pattern inspection method comprising:
imaging a first pattern formed in a first area of a substrate to acquire a first pattern image;
associating the first pattern image with design information for the first pattern to detect a defect by a die-to-database inspection;
comparing the number of the detected defect with a prepared first threshold, and when the number of the detected defects is equal to or less than the first threshold, outputting the detected defect as an inspection result;
imaging a second pattern to acquire a second pattern image when the number of the detected defect is more than the first threshold, the second pattern being formed in a second area different from the first area within the substrate and being designed to comprise the same shape as the first pattern; and
comparing the first pattern image with the second pattern image to further detect a defect by a die-to-die inspection, and outputting the further detected defects as an inspection result,
wherein the further detection of defect by the die-to-die inspection comprises:
detecting an edge of the first pattern from the first pattern image, and calculating a value of a gradient of a detected edge profile of the first pattern;
comparing the value of the gradient with a prepared second threshold; and
detecting an edge of the second pattern from the second pattern image and comparing the edge of the second pattern with the edge of the first pattern to detect a defect when the calculated value of the gradient is equal to or more than the second threshold, or calculating a pixel value of the first pattern image and a pixel value of the second pattern image and comparing these pixel values to detect a defect when the calculated value of the gradient is less than the second threshold.
2. A pattern inspection method comprising:
imaging a first pattern formed in a first area of a substrate to acquire a first image;
detecting an edge of the first pattern from the first image, and calculating a gradient of a detected edge profile of the first pattern;
comparing the gradient with a prepared first threshold; and
detecting a defect by an outer shape comparison using at least one of a die-to-database inspection and a die-to-die inspection when the calculated value of the gradient is equal to or more than the first threshold, or imaging a second pattern to acquire a second image and comparing pixel values of the first image and the second image to detect a defect when the calculated value of the gradient is less than the first threshold, the second pattern being formed in a second area different from the first area within the substrate and being designed to comprise the same shape as the first pattern.
3. The method of claim 2 , wherein the defect detection by the outer shape comparison comprises:
comparing the number of the defect detected by the die-to-database inspection with a prepared second threshold, and when the number of the detected defect is equal to or less than the second threshold, outputting the detected defect as an inspection result, or when the number of the detected defect is more than the second threshold, imaging the second pattern to acquire a second image, further detecting a defect by the die-to-die inspection based on a comparison between the first image and the second image, and outputting the further detected defect as an inspection result.
4. The method of claim 2 , further comprising, in the defect detection by the outer shape comparison, selecting the die-to-database inspection or the die-to-die inspection depending on whether a database in an inspection apparatus is available.
5. The method of claim 2 , wherein the first threshold is set for each of inspection areas obtained by dividing the entire area of the substrate.
6. The method of claim 2 , wherein the patterns to be inspected comprise a plurality of kinds of patterns; and
the first threshold is set for each kind of pattern.