Method and apparatus for detecting defects in wafers
First Claim
Patent Images
1. A method for inspecting a wafer including a multiplicity of dies, the method comprising:
- dividing an image of at least a portion of said wafer into a plurality of sub-images each representing a sub-portion of said wafer; and
selecting at least one defect candidate within each said sub-image, by comparing each sub-image to a corresponding sub-image of a reference comprising a representation, which is assumed to be defectless, of said portion of said wafer.
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Abstract
A method for inspecting a wafer including a multiplicity of dies, the method including dividing an image of at least a portion of the wafer into a plurality of sub-images each representing a sub-portion of the wafer and selecting at least one defect candidate within each sub-image by comparing each sub-image to a corresponding sub-image of a reference including a representation, which is assumed to be faultless, of the portion of the wafer.
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Citations
47 Claims
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1. A method for inspecting a wafer including a multiplicity of dies, the method comprising:
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dividing an image of at least a portion of said wafer into a plurality of sub-images each representing a sub-portion of said wafer; and
selecting at least one defect candidate within each said sub-image, by comparing each sub-image to a corresponding sub-image of a reference comprising a representation, which is assumed to be defectless, of said portion of said wafer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 16, 17, 18, 19, 20, 34, 35, 36, 37, 38)
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13. A method for inspecting a wafer including a multiplicity of dies, the method comprising:
comparing a first image of at least a portion of the wafer to a reference image and identifying locations in the first image which differ from the reference image by more than a threshold value wherein said threshold value used for an individual location within said first image is a function of estimated noise between different images of said individual location. - View Dependent Claims (14, 15, 39)
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21. A method for inspecting at least a portion of a wafer comprising a multiplicity of dies comprising:
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inspecting a multiplicity of locations within an image of at least a portion of said wafer to be inspected and selecting a plurality of defect candidates;
scoring the plurality of defect candidates and selecting a predetermined number of the highest scoring defect candidates for further defect detection analysis. - View Dependent Claims (22, 23, 40)
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24. A method for inspecting a wafer including a multiplicity of dies comprising:
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for each of a multiplicity of locations of the wafer, sorting discrepancies found between individual ones of a plurality of representations of said wafer location into larger and smaller discrepancies; and
determining whether or not each location is a defect, based on the magnitude of at least one larger discrepancy for that location relative to the magnitude of at least one smaller discrepancy for that location. - View Dependent Claims (41)
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25. A method for inspecting a defective image of a wafer including a multiplicity of dies, the method comprising:
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generating a difference image comprising differences between a multiplicity of locations within the defective image and a corresponding multiplicity of locations within a reference, the difference image defining a distribution of difference values; and
selecting, as defects, individual ones from among said multiplicity of locations whose difference values are characterized as defects based on a defect definition function which is a predetermined function of said distribution of difference values. - View Dependent Claims (26, 27, 28, 29, 30, 31, 32, 33, 42)
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43. Apparatus for inspecting a wafer including a multiplicity of dies comprising:
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an image divider, operative to divide an image of at least a portion of said wafer into a plurality of sub-images each representing a sub-portion of said wafer; and
a defect candidate identifier, operative to select at least one defect candidate within each said sub-image by comparing each sub-image to a corresponding sub-image of a reference comprising a representation, which is assumed to be defectless, of said portion of said wafer.
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44. Apparatus for inspecting a wafer including a multiplicity of dies comprising:
an image comparator, operative to compare a first image of at least a portion of the wafer to a reference image and to identify locations in the first image which differ from the reference image by more than a threshold value wherein said threshold value used for an individual location within said first image is a function of estimated noise between different images of said individual location.
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45. Apparatus for inspecting a at least a portion of a wafer including a multiplicity of dies comprising:
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a defect candidate identifier, operative to inspect a multiplicity of locations within an image of a wafer to be inspected and to select a plurality of defect candidates; and
a defect candidate analyzer, operative to score the plurality of defect candidates and to select a predetermined number of the highest scoring defect candidates for further defect detection analysis.
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46. Apparatus for inspecting a wafer including a multiplicity of dies comprising:
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a discrepancy sorter operative, for each of a multiplicity of locations of said wafer, to sort discrepancies found between individual ones of a plurality of representations of said wafer location into larger and smaller discrepancies; and
a discrepancy analyzer, operative to determine whether or not each location is a defect, based on the magnitude of at least one larger discrepancy for that location relative to the magnitude of at least one smaller discrepancy for that location.
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47. Apparatus for inspecting a defective image of a wafer including a multiplicity of dies comprising:
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a difference image generator, operative to generate a difference image comprising differences between a multiplicity of locations within the defective image and a corresponding multiplicity of locations within a reference, the difference image defining a distribution of difference values; and
a defect identifier operative to identify, as defects, individual ones from among said multiplicity of locations whose difference values are characterized as defects based on a defect definition function which is a predetermined function of said distribution of difference values.
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Specification