Microlithographic reduction projection catadioptric objective
US6873476B2 · kind B2 · utility
56Cited by
40References
38Claims
0Family size
Assignee
Inventor
Key dates
| Filing date | Jan 12, 2001 |
| Grant date | Mar 29, 2005 |
| Priority date | — |
| Expiry date | Aug 17, 2021 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F7/70358
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
The invention concerns a microlithographic reduction projection catadioptric objective having an even number greater than two of curved mirrors, being devoid of planar folding mirrors and featuring an unobscured aperture. The objective has a plurality of optical elements, and no more than two optical elements deviate substantially from disk form. The objective has an object side and an image side, and has in sequence from the object side to the image side a catadioptric group providing a real intermediate image, a catoptric or catadioptric group providing a virtual image, and a dioptric group providing a real image.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.