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Method, program product and apparatus for model based scattering bar placement for enhanced depth of focus in quarter-wavelength lithography

  • US 20060075377A1
  • Filed: 08/22/2005
  • Published: 04/06/2006
  • Est. Priority Date: 08/24/2004
  • Status: Active Grant
First Claim
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1. A method of generating a mask having optical proximity correction features disposed therein, said method comprising the steps of:

  • (a) obtaining a desired target pattern having features to be imaged on a substrate;

    (b) determining a first focus setting to be utilized when imaging said mask;

    (c) determining a first interference map based on said target pattern and said first focus setting;

    (d) determining a first seeding site representing the optimal placement of an assist feature within said mask relative to a feature to be imaged on the basis of said first interference map;

    (e) selecting a second focus setting which represents a predefined amount of defocus relative to said first focus setting;

    (f) determining a second interference map based on said target pattern and said second focus setting;

    (g) determining a second seeding site representing the optimal placement of an assist feature within said mask relative to said feature to be imaged on the basis of said second interference map; and

    (h) generating an assist feature having a shape which encompasses both said first seeding site and said second seeding site.

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