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Etch metric sensitivity for endpoint detection

  • US 10,032,681 B2
  • Filed: 03/02/2016
  • Issued: 07/24/2018
  • Est. Priority Date: 03/02/2016
  • Status: Active Grant
First Claim
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1. A method of generating a computational model that relates measured optical signals produced by optical energy interacting with features etched on a substrate to values of a target geometric parameter of the features etched on the substrate, the method comprising:

  • determining a range of the measured optical signals for use in the computational model, wherein determining the range comprises;

    identifying a first change in the measured optical signals in the range due to a variation in values of a non-target geometric parameter,identifying a second change in the measured optical signals in the range due to a variation in values of the target geometric parameter, anddetermining that the second change is greater than the first change;

    providing a training set having members with values of the optical signals in the range, wherein each member of the training set comprises (i) a value of the target geometric parameter of the features etched in the substrate, and (ii) an associated optical signal produced from etched features having the value of the target geometric parameter of the features etched in the substrate; and

    producing the computational model from the training set.

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