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Apparatus and methods for detecting overlay errors using scatterometry

  • US 7,289,213 B2
  • Filed: 02/23/2004
  • Issued: 10/30/2007
  • Est. Priority Date: 02/22/2003
  • Status: Active Grant
First Claim
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1. A combined scatterometry mark, comprising:

  • a scatterometry critical dimension (CD) or profile target capable of being measured to determine CD or profile information; and

    a scatterometry overlay target disposed over the scatterometry CD or profile target, the scatterometry overlay target and the scatterometry CD or profile target together forming a scatterometry mark capable of being measured to determine overlay based on a scatterometry overlay technique without using calibration or a model regression technique,wherein the scatterometry overlay technique is a phase based technique that includes representing each measured optical signal as a set of periodic functions having a plurality of known parameters and an unknown overlay error parameter and analyzing the set of periodic functions to solve for the unknown overlay error parameter to thereby determine the overlay error.

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