Optical correction plate, and its application in a lithographic projection apparatus
US6373552B1 · kind B1 · utility
14Cited by
9References
11Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Jan 18, 2000 |
| Grant date | Apr 16, 2002 |
| Priority date | — |
| Expiry date | Jan 18, 2020 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F7/70308
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A plate with substantially constant thickness is used to compensate for the residual distortion in the image projected by a high-quality projection lens for lithography. The two surfaces of the plate have an identical aspherical profile, whose shape has been calculated using the measured distortion map of the lithographic objective. The figuring process applied to the plate uses the principle of polishing in the presence of an elastic deformation, so as to achieve the desired aspherical shape on both sides.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.