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Laser imaging system for inspection and analysis of sub-micron particles

  • US 5,963,314 A
  • Filed: 10/15/1996
  • Issued: 10/05/1999
  • Est. Priority Date: 06/17/1993
  • Status: Expired due to Term
First Claim
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1. An imaging system comprising:

  • means for supporting a semiconductor wafer to be imaged by the imaging system;

    means for inspecting the wafer to determine the efficacy of a process previously performed on the wafer, the inspecting means including;

    means for emitting laser light of a plurality of wavelengths;

    means for directing the laser light toward the supporting means;

    means for measuring a first intensity of laser light reflected from a plurality of points on a surface of the wafer to define a plurality of test values, each of the test values representing the intensity of light reflected from one of the plurality of points on the wafer surface; and

    means for storing the plurality of test values;

    means for comparing the stored plurality of test values to a plurality of reference values to identify differences between the test values and the reference values, wherein the differences between the test and reference values indicate the presence of an optical anomaly; and

    means for analyzing the differences to determine the nature and origin of the anomaly.

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