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Threshold determination in an inspection system

  • US 8,260,035 B2
  • Filed: 09/22/2006
  • Issued: 09/04/2012
  • Est. Priority Date: 09/22/2006
  • Status: Active Grant
First Claim
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1. A method for inspecting a surface of a semiconductor workpiece, the method comprising:

  • providing a surface inspection system and using the surface inspection apparatus to cause laser light to impinge upon a test location on the workpiece surface and thereby cause the laser light to emerge from the surface as returned light comprising at least one of reflected light and scattered light;

    collecting the returned light and generating a signal from the returned and collected light, the signal comprising a signal value representative of a characteristic of the workpiece surface at the test location;

    providing a plurality of defect threshold candidates, the violation of which indicates the presence of a preexisting defect on the workpiece,receiving with the surface inspection system an input from a user, where the input represents a desired sensitivity for the inspection of the workpiece,causing the surface inspection system to automatically select a threshold from among the plurality of defect threshold candidates based on the input from the user and a plurality of prior signal values from secondary test locations, such that the threshold selected for the test location is different from the threshold selected for a different test location on the workpiece;

    comparing the threshold to the signal value to obtain a difference value;

    using the difference value to assess the characteristic of the workpiece surface at the test location; and

    using the surface inspection system to automatically cause the method to be repeated for a plurality of test locations on the workpiece surface.

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