Optical inspection method and apparatus

  • US 5,982,921 A
  • Filed: 12/03/1997
  • Issued: 11/09/1999
  • Est. Priority Date: 11/16/1990
  • Status: Expired due to Term
First Claim
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1. An inspection device for inspecting a patterned substrate, comprising:

  • a light source providing a light beam;

    an optical system for directing the beam to impinge upon a defined spot on the substrate;

    a plurality of detectors spaced apart from each other but concurrently directed at the defined spot, said plurality of detectors providing a first and a second reflection data streams corresponding to reflected light from the spot to first and second directions;

    a memory having a first and a second reference data streams;

    a comparator comparing said first reflection data stream to said first reference data stream and providing a first comparison signal, and comparing said second reflection data stream to said second reference data stream and providing a second comparison signal.

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