Vortex phase shift mask for optical lithography
US6811933B2 · kind B2 · utility
3Cited by
4References
9Claims
0Family size
Inventor
Key dates
| Filing date | Jul 1, 2002 |
| Grant date | Nov 2, 2004 |
| Priority date | — |
| Expiry date | Jul 21, 2022 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F1/34
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A photolithography method and apparatus for producing minima of light intensity corresponding to a point in a phase shift mask is described. The phase shift in the light produced by the mask varies in a spiral fashion around the point so that the phase shift measured along lines drawn across the surface of the mask which pass through the point have a 180° jump at the point, and lines passing around the point have no jumps between 130° and 230°, and most preferably no jumps between 100° and 260°.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.