EUV focus monitoring systems and methods
US9823585B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Sep 14, 2015 |
| Grant date | Nov 21, 2017 |
| Priority date | — |
| Expiry date | Sep 28, 2035 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F7/70641
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
Systems and methods for monitoring the focus of an EUV lithography system are disclosed. Another aspect includes a method having operations of measuring a first shift value for a first patterned set of sub-structures of a focus test structure on a wafer and measuring a second shift value for a second patterned set of sub-structures of the test structure on the wafer. The test structure may be formed on the wafer using asymmetric illumination, with the first patterned set of sub-structures having a first pitch and the second patterned set of sub-structures having a second pitch that is different from the first pitch. The method may further include determining a focus shift compensation for an illumination system based on a difference between the first shift value and the second shift value.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.