Method of photomask correction and its optimization using localized frequency analysis
US7233887B2 · kind B2 · utility
Inventor
Key dates
| Filing date | Jan 21, 2003 |
| Grant date | Jun 19, 2007 |
| Priority date | — |
| Expiry date | Oct 14, 2024 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F1/36
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A method of level assist feature OPC layout is described using frequency model-based approach. Through low-pass spatial frequency filtering of a mask function, the local influence of zero diffraction energy can be determined. By determining isofocal intensity threshold requirements of an imaging process, a mask equalizing function can be designed. This provides the basis for frequency model-based assist feature layout. By choosing assist feature parameters that meet the requirements of the equalizing function, through-pitch focus and dose matching is possible for large two dimensional mask fields. The concepts introduced also lead to additional assist feature options and design flexibility.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.