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Apparatus and methods for determining overlay of structures having rotational or mirror symmetry

  • US 20070008533A1
  • Filed: 09/14/2005
  • Published: 01/11/2007
  • Est. Priority Date: 08/30/2000
  • Status: Active Grant
First Claim
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1. A semiconductor target for determining a relative shift between two or more successive layers of a substrate or between two or more separately generated patterns on a single layer of a substrate, the target comprising:

  • a plurality of first structures having a first center of symmetry (COS) or first line of symmetry (LOS) and being arranged to determine the relative shift in an x direction by analyzing an image of the first structures; and

    a plurality of second structures having a second COS or second LOS and being arranged to determine the relative shift in an x direction by analyzing an image of the second structures, wherein the first COS or LOS has a different location than the second COS or LOS.

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