Device, EUV-lithographic device and method for preventing and cleaning contamination on optical elements
US7060993B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Mar 7, 2003 |
| Grant date | Jun 13, 2006 |
| Priority date | — |
| Expiry date | Mar 16, 2023 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F7/70916
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
The invention relates to a method for preventing contamination on the surfaces of optical elements comprising a multi-layer system, during the exposure thereof to radiation at signal wave lengths in an evacuated closed system comprising a residual gas atmosphere, whereby the photocurrent generated by means of photo emission from the radiated surface of the multi-layer system is measured. The photocurrent is used to regulate the gas composition of the residual gas. The gas composition is altered according to at least one lower and one upper threshold value of the photocurrent. The invention also relates to a device for regulating the contamination on the surface of at least one optical element during exposure and an EUV-lithographic device and a method for cleaning the surfaces of the optical elements contaminated by carbon.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.