Gradient immersion lithography
US6954256B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Oct 31, 2003 |
| Grant date | Oct 11, 2005 |
| Priority date | — |
| Expiry date | Oct 31, 2023 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S430/162
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
In a lithographic projection apparatus, a space between an optical element is filled with a first fluid and a second fluid separated by a transparent plate. The first and second fluids have first and second indices of refraction, respectively, that are different from one another. The first fluid is provided between a substrate and the transparent plate and has an index of refraction similar to the index of refraction of the substrate. The second fluid is provided between the transparent plate and the optical element and has an index of refraction similar to the index of refraction of the optical element. The transparent plate has a third index of refraction between the first and second indices of refraction and may be equal to the first index of refraction or the second index of refraction. A device manufacturing method includes filling a space between the optical element and the substrate with at least two fluids having different indices of refraction.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.