Illumination optimization for specific mask patterns
US6871337B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Feb 22, 2002 |
| Grant date | Mar 22, 2005 |
| Priority date | — |
| Expiry date | Sep 24, 2022 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F7/705
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A method and apparatus for microlithography. The method and apparatus include optimizing illumination modes based on characteristics of a specific mask pattern. The illumination is optimized by determining an appropriate illumination mode based on diffraction orders of the reticle, and the autocorrelation of the projection optic. By elimination of parts of the illumination pattern which have no influence on modulation, excess DC light can be reduced, thereby improving depth of focus. Optimization of mask patterns includes addition of sub-resolution features to reduce pitches and discretize the probability density function of the space width.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.