The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Nov. 08, 2005
Filed:
Feb. 28, 2003
Lars W. Liebmann, Poughquag, NY (US);
Allen H. Gabor, Katonah, NY (US);
Ronald L. Gordon, Poughkeepsie, NY (US);
Carlos A. Fonseca, Staten Island, NY (US);
Martin Burkhardt, White Plains, NY (US);
Lars W. Liebmann, Poughquag, NY (US);
Allen H. Gabor, Katonah, NY (US);
Ronald L. Gordon, Poughkeepsie, NY (US);
Carlos A. Fonseca, Staten Island, NY (US);
Martin Burkhardt, White Plains, NY (US);
International Business Machines Corporation, Armonk, NY (US);
Abstract
A method of designing a mask for imaging an integrated circuit (IC) design layout is provided to efficiently configure subresolution assist features (SRAFs) corresponding to an optimally configured annular illumination source of a lithographic projection system. A critical pitch is identified for the IC design, and optimal inner and outer radial coordinates of an annular illumination source are determined so that the resulting image projected through the mask will be optimized for the full range of pitches in the design layout. A relationship is provided for determining an optimal inner radius and outer radius for the annular illumination source. The number and placement of SRAFs are added to the mask design so that the resulting range of pitches substantially correspond to the critical pitch. The method of configuring SRAFs so that the image will have optimal characteristics, such as good contrast and good depth of focus, is fast.