Surfacing of metal fluoride excimer optics
US7128984B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Aug 31, 2004 |
| Grant date | Oct 31, 2006 |
| Priority date | — |
| Expiry date | Oct 26, 2024 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B1/14
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
The invention is directed to improved coated metal fluoride single crystal optical elements suitable for use in below 250 nm optical lithography, and particularly below 200 nm lithography. The coated elements of the invention can be lenses, windows, prisms and other elements used in lithographic methods, including the laser sources used therein. The invention is also directed to a method of removing the quasi-Bielby layer formed when a shaped optical element is polished. Removal of the quasi-Bielby layer prior to coating results in improved durability and optical transmission characteristics of the coated lenses. The coating material can be any material that does not impede the transmission of below 250 nm electromagnetic radiation. Fluorine doped silicon dioxide is the preferred coating material.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.