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Sample inspection apparatus and sample inspection method

  • US 5,960,106 A
  • Filed: 03/30/1995
  • Issued: 09/28/1999
  • Est. Priority Date: 03/31/1994
  • Status: Expired due to Term
First Claim
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1. A sample inspection apparatus comprising:

  • light radiation means for radiating light on a sample on which a pattern relating to fabrication of a semiconductor device is formed;

    acquiring means for sensing the light which has passed through the sample, thereby acquiring measured image data constituting a light transmission image of said pattern;

    setting means for setting a predetermined lower limit value and a predetermined upper limit value as signal amplitude values for the measured image data acquired by said acquiring means;

    normalizing means for normalizing the measured image data acquired by said acquiring means such that a range of amplitude between the lower and upper limit values set by said setting means is 0% to 100% of an ideal amplitude;

    clamping means for clamping a portion of the measured image data acquired by said acquiring means, which exceeds the predetermined upper limit value, with the normalized measured image data corresponding to the upper limit value;

    gain multiplying means for inverting a portion of the measured image data that is lower than the lower limit value at the lower limit value and multiplying the inverted measured image data portion by a predetermined gain; and

    defect detection means for detecting a defect in said pattern by comparing the normalized, clamped, and multiplied measured image data and design data of the pattern.

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