Illumination optical unit for EUV projection lithography, and optical system comprising such an illumination optical unit
US9645501B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Aug 25, 2014 |
| Grant date | May 9, 2017 |
| Priority date | — |
| Expiry date | Jun 15, 2035 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH05G2/0086
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
An illumination optical unit for EUV projection lithography guides illumination light to an illumination field, in which a lithography mask can be arranged. A facet mirror with a plurality of facets guides the illumination light to the illumination field. Respectively one illumination channel which guides an illumination light partial beam is predetermined by one of the facets. Exactly one illumination channel is guided over respectively one of the facets. The illumination optical unit is configured so that, at any time and at any point in the illumination field when the illumination optical unit is in operation, any pairs of illumination light partial beams guided over different illumination channels are incident on this illumination field point at times of incidence, the time difference of which is greater than a coherence duration of the illumination light.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.