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Method for time-evolving rectilinear contours representing photo masks

  • US 7,757,201 B2
  • Filed: 02/12/2007
  • Issued: 07/13/2010
  • Est. Priority Date: 04/06/2003
  • Status: Active Grant
First Claim
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1. A computer implemented method for determining a mask pattern to be used on a photo-mask in a photolithographic process, wherein the photo-mask has a plurality of distinct types of regions having distinct optical properties, comprising:

  • providing a first mask pattern that includes a plurality of distinct types of regions corresponding to the distinct types of regions of the photo-mask;

    using a processor to calculate a gradient of a function, wherein the function depends on the first mask pattern and an estimate of a wafer pattern that results from the photolithographic process utilizing at least a portion of the first mask pattern, and wherein the gradient is calculated in accordance with a formula obtained by taking a derivative of the function; and

    generating a second mask pattern based, at least in part, on the gradient of the function.

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