Pitch-based subresolution assist feature design
US6964032B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Feb 28, 2003 |
| Grant date | Nov 8, 2005 |
| Priority date | — |
| Expiry date | Mar 28, 2024 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F2119/18
- WIPO fieldOptics
- WIPO sectorInstruments
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.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.