Lithography contrast enhancement technique by varying focus with wavelength modulation
US6829040B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Nov 7, 2003 |
| Grant date | Dec 7, 2004 |
| Priority date | — |
| Expiry date | Nov 7, 2023 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F7/70333
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A projection lithography system exposes a photo sensitive material on a surface of a semiconductor substrate that includes surface height variations between a high level and a low level. The system comprises an illumination source projecting illumination within a narrow wavelength band centered about a nominal wavelength on an optic path towards the substrate during an exposure period. A wavelength modulation system within the optic path comprises means for chromatically separating the narrow wavelength band into at least two sub-bands, the first sub-band being smaller than the narrow wavelength band and centered about a first sub-band wavelength and the second sub-band being smaller than the narrow wavelength band and centered about a second sub-band wavelength and means for passing each of the first sub-band and the second sub-band during distinct time periods within the exposure period.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.