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Optimized polarization illumination

  • US 8,395,757 B2
  • Filed: 05/04/2010
  • Issued: 03/12/2013
  • Est. Priority Date: 12/19/2003
  • Status: Active Grant
First Claim
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1. A method of optimizing polarization of an illumination of a pattern to be formed in a surface of a substrate, the illumination originating from an illuminator plane comprising individual pixels from which light illuminates the pattern for being projected via a projection system in the surface of the substrate, the method comprising the steps of:

  • (a) selecting a plurality of fragmentation points in the pattern;

    (b) determining an illumination intensity for at least one pixel in an illuminator plane for at least two polarization states;

    (c) determining an image log slope at the fragmentation points at substrate level for the at least one pixel on the illuminator plane for the at least two polarization states;

    (d) determining a minimum image log slope (ILS) for the fragmentation points for each of the at least two polarization states;

    (e) selecting an optimal polarization state for the at least one pixel in the illuminator plane that maximizes the minimum ILS; and

    (f) repeating steps (a)-(e) for each of a plurality of pixels in the illuminator plane.

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