Methods and apparatus for predicting performance of a measurement method, measurement method and apparatus
US11626704B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Feb 22, 2018 |
| Grant date | Apr 11, 2023 |
| Priority date | — |
| Expiry date | Mar 9, 2040 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH05G2/002
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A radiation source arrangement causes interaction between pump radiation (340) and a gaseous medium (406) to generate EUV or soft x-ray radiation by higher harmonic generation (HHG). The operating condition of the radiation source arrangement is monitored by detecting (420/430) third radiation (422) resulting from an interaction between condition sensing radiation and the medium. The condition sensing radiation (740) may be the same as the first radiation or it may be separately applied. The third radiation may be for example a portion of the condition sensing radiation that is reflected or scattered by a vacuum-gas boundary, or it may be lower harmonics of the HHG process, or fluorescence, or scattered. The sensor may include one or more image detectors so that spatial distribution of intensity and/or the angular distribution of the third radiation may be analyzed. Feedback control based on the determined operating condition stabilizes operation of the HHG source.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.