Metrology method and apparatus, lithographic apparatus, device manufacturing method and substrate
US8411287B2 · kind B2 · utility
81Cited by
1References
33Claims
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Key dates
| Filing date | Aug 12, 2010 |
| Grant date | Apr 2, 2013 |
| Priority date | — |
| Expiry date | Jul 27, 2031 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F7/70616
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A metrology apparatus is arranged to illuminate a plurality of targets with an off-axis illumination mode. Images of the targets are obtained using only one first order diffracted beam. Where the target is a composite grating, overlay measurements can be obtained from the intensities of the images of the different gratings. Overlay measurements can be corrected for errors caused by variations in the position of the gratings in an image field.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.