Diffraction pupil filler modified illuminator for annular pupil fills
US5663785A · kind A · utility
61Cited by
3References
5Claims
0Family size
Assignee
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Key dates
| Filing date | May 24, 1995 |
| Grant date | Sep 2, 1997 |
| Priority date | — |
| Expiry date | May 24, 2015 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F7/70241
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
Uniform illumination of a photomask in optical lithography is achieved with annular illumination of the conjugate pupil plane in a lithography tool. A spinning diffraction filter is placed in a stepper so as to provide annular illumination on a time averaged basis. This approach provides annular illumination for resolution enhancement in an easily manufacturable and flexible way and without significant loss of light intensity. No illuminator redesign in the photolithographic exposure tool is required.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.