Apparatus and method for inspection of a patterned object by comparison thereof to a reference
First Claim
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1. An inspection method comprising:
- providing a patterned object to be inspected and compared with a reference;
inspecting the patterned object and providing an output of information relating to visually sensible characteristics of the patterned object, said output of information comprising gray level information regarding the patterned object;
converting said gray level information into binary level information regarding the patterned object, the gray level to binary level conversion being carried out at subpixel accuracy;
comparing binary level information relating to visually sensible characteristics of the patterned object to binary level information relating to corresponding visual sensible characteristics of the reference; and
comparing gray level information relating to visually sensible characteristics of the patterned object to gray level information relating to corresponding visually sensible characteristics of the reference.
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Abstract
The present invention seeks to provide an improved system for inspection of and detection of defects in objects such as reticles, photomasks, semiconductor wafers, flat panel displays and other patterned objects. Preferably, the system has two or more stages, whereby the object is examined separately for fine defects, preferably by inspecting a binary level representation of the object, and for ultra fine defects, preferably by inspecting a gray level representation of the object. The system also preferably includes reinspection apparatus for reinspection of detected defects, thereby to reduce the false alarm rate, and for classifying the remaining defects by size, area and type.
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Citations
27 Claims
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1. An inspection method comprising:
- providing a patterned object to be inspected and compared with a reference;
inspecting the patterned object and providing an output of information relating to visually sensible characteristics of the patterned object, said output of information comprising gray level information regarding the patterned object; converting said gray level information into binary level information regarding the patterned object, the gray level to binary level conversion being carried out at subpixel accuracy; comparing binary level information relating to visually sensible characteristics of the patterned object to binary level information relating to corresponding visual sensible characteristics of the reference; and comparing gray level information relating to visually sensible characteristics of the patterned object to gray level information relating to corresponding visually sensible characteristics of the reference. - View Dependent Claims (26, 27)
- providing a patterned object to be inspected and compared with a reference;
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2. An inspection system comprising:
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apparatus for comparing an inspected object to a reference and providing an output of information relating to visually sensible characteristics of the inspected object, said output of information comprising gray level information regarding the patterned object; a binarizing unit operative to convert said gray level information into binary level information regarding the patterned object, the gray level to binary level conversion being carried out at subpixel accuracy; binary level comparison apparatus for comparing binary level information relating to visually sensible characteristics of the inspected object to binary level information relating to visually sensible characteristics of the reference; and gray level comparison apparatus for comparing gray level information relating to visually sensible characteristics of the inspected object to gray level information relating to visually sensible characteristics of the reference. - View Dependent Claims (3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. An inspection system comprising:
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apparatus for providing at least one representation of visually sensible characteristics of an inspected object; first apparatus for comparing an individual one of said at least one representation of said inspected object to a reference and providing an output indication of differences; and second apparatus for comparing an individual one of said at least one representation to a reference, thereby to complement said first apparatus by enhancing said indication of differences provided by said first apparatus, wherein at least one of said first and second apparatus employ subpixel binarization to align the inspected object to the reference.
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20. An inspection system comprising:
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apparatus for comparing an inspected object to a reference and providing an output of information relating to visually sensible characteristics of the inspected object; first apparatus for providing an indication of differences between the inspected object and the reference; and second apparatus for automatically carrying out a second inspection of visually sensible characteristics of at least some areas of the inspected object and for complementing said first apparatus and comprising apparatus for enhancing said indication of differences provided by said first apparatus, wherein at least one of said first apparatus and second apparatus performs alignment based on subpixel binarization. - View Dependent Claims (21, 22)
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23. An inspection method comprising:
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providing a patterned object to be inspected and compared with a reference; carrying out a first inspection of the patterned object and providing an output of information relating to visually sensible characteristics of the patterned object; comparing the information relating to the visually sensible characteristics of the patterned object to the reference, thereby to provide an indication of differences between the patterned object and the reference; and automatically carrying out a second inspection of the visually sensible characteristics of at least some areas of the patterned object thereby to enhance said indication of differences, wherein at least one of said first and second inspections include alignment based on subpixel binarization.
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24. An inspection method comprising:
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providing a patterned object to be inspected and compared with a reference; carrying out a first inspection of the patterned object and providing an output of information relating to visually sensible characteristics of the patterned object; comparing the information relating to the visually sensible characteristics of the patterned object to the reference, thereby to provide an indication of differences between the patterned object and the reference; and automatically carrying out a second inspection of the visually sensible characteristics of at least some areas of the patterned object thereby to enhance said indication of differences, wherein the second inspection of characteristics of each reinspected area of the patterned object is off-line relative to the first inspection of the patterned object.
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25. An inspection method comprising:
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providing at least one representation of visually sensible characteristics of an inspected object; comparing an individual one of said at least one representations of said inspected object to a reference and providing an output indication of differences; and comparing an individual one of said at least one representations to a reference, thereby to complement said first comparing operation by enhancing said output indication of differences, wherein at least one of said first comparing operation and said second comparing operation employ subpixel binarization to align the inspected object to the reference.
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Specification