Focus masking structures, focus patterns and measurements thereof
US6884552B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Nov 7, 2002 |
| Grant date | Apr 26, 2005 |
| Priority date | — |
| Expiry date | Jul 9, 2023 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F1/28
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
Methods and device structures used to determine the focus quality of a photolithographic pattern or a photolithographic system are disclosed. One aspect of the invention relates to focus masking structures configured to form focus patterns that contain focus information relating to the focus quality. The focus masking structures generally include a plurality of parallel source lines that are separated by alternating phase shift zones. Another aspect of the invention relates to focus patterns that change with changes in focus. The focus patterns generally include a plurality of periodic structures that form measurable shifts therebetween corresponding to the sign and magnitude of defocus. Another aspect of the invention relates to a method of determining the focus quality of a photolithographic pattern or a photolithographic system. The method generally includes: providing a focus masking structure, forming a focus pattern on a work piece with the focus masking structure, and obtaining focus information from the focus pattern. The focus information may be obtained using a variety of techniques, as for example, scatterometry techniques, scanning techniques, imaging techniques, phase …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.