Suppression filter, radiation collector and radiation source for a lithographic apparatus; method of determining a separation distance between at least two reflective surface levels of a suppression filter
US10678140B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Aug 2, 2016 |
| Grant date | Jun 9, 2020 |
| Priority date | — |
| Expiry date | Aug 25, 2036 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH05G2/0082
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
Disclosed is a suppression filter having a profile defining at least two reflective surface levels, each reflected surface level being separated by a separation distance. The separation distance is such that the reflective suppression filter is operable to substantially prevent specular reflection of radiation at a first wavelength and at a second wavelength incident on said reflective suppression filter. Also disclosed is a radiation collector, radiation source and lithographic apparatus comprising such a suppression filter, and to a method of determining a separation distance between at least two reflective surface levels of a suppression filter.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.