Overlay measurements using zero-order cross polarization measurements
US6947141B2 · kind B2 · utility
18Cited by
21References
20Claims
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Key dates
| Filing date | Sep 8, 2004 |
| Grant date | Sep 20, 2005 |
| Priority date | — |
| Expiry date | Sep 8, 2024 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F7/70633
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
Overlay measurements for a semiconductor wafer are obtained by forming a periodic grating on the wafer having a first set of ridges and a second set of ridges. The first and second sets of ridges are formed on the wafer using a first mask and a second mask, respectively. After forming the first and second sets of gratings, zero-order cross polarization measurements of a portion of the periodic grating are obtained. Any overlay error between the first and second masks used to form the first and second sets of gratings is determined based on the obtained zero-order cross polarization measurements.
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