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Illumination-Source Shape Definition in Optical Lithography

  • US 20130074017A1
  • Filed: 09/14/2012
  • Published: 03/21/2013
  • Est. Priority Date: 09/16/2011
  • Status: Active Grant
First Claim
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1. A method for determining lithographic processing conditions for a lithographic process, the method comprising:

  • obtaining characteristics of an illumination source and a mask design, the mask design comprising a lithography pattern;

    performing a first optimization for combined optimizing of at least the illumination source characteristics and the mask design characteristics for the lithographic process, whereby for the first optimization non-rectangular sub-resolution assist features for the mask are allowed;

    determining from the first optimization a set of optimized illumination source characteristics;

    performing at least one additional optimization for optimizing the mask design characteristics of the lithographic process, whereby for the at least one additional optimization the presence of non-rectangular sub-resolution assist features for the mask design is substantially excluded and whereby the at least one additional optimization takes into account the set of optimized illumination source characteristics; and

    determining from the at least one additional optimization a set of optimized mask design characteristics substantially excluding non-rectangular sub-resolution assist features.

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