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Automated visual inspection apparatus for detecting defects and for measuring defect size

  • US 5,917,934 A
  • Filed: 03/15/1996
  • Issued: 06/29/1999
  • Est. Priority Date: 03/15/1996
  • Status: Expired due to Fees
First Claim
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1. Apparatus for inspecting a device having a plurality of substantially longitudinally-shaped openings, each opening having two opposite ends, to detect etch defects in said device, said apparatus comprising:

  • imaging means for generating an image signal of said device representing light intensity values of a plurality of pixels;

    processing means for processing said image signal to form data signals representing light intensity values of groups of said pixels;

    filtering means for removing signals corresponding to said ends from said data signals; and

    pairing means for pairing two of said data signals to form a pair of data signals if the groups of pixels represented by the two data signals satisfy at least one predetermined condition whereby said pair of data signals represents an etch defect;

    wherein said predetermined condition includes the condition that within each of the groups of pixels represented by the two data signals the pixels are adjacent each other wherein said pairing means includes means for estimating a size of an area of said device imaged by the groups of pixels represented by the two data signals and for generating an area signal representing said size of said area wherein said means for estimating a size includes;

    means for determining a height and a center of each of the groups of pixels represented by the two data signals;

    means for averaging together the respective heights of the groups of pixels represented by the two data signals to form an average height value;

    calculating means for calculating a distance between the centers of the groups of pixels represented by the two data signals to form a width value; and

    multiplying means for multiplying said average height value by said width value to produce said size.

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