Abbe arm calibration system for use in lithographic apparatus
US6730920B2 · kind B2 · utility
5Cited by
12References
20Claims
0Family size
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Key dates
| Filing date | Jan 12, 2001 |
| Grant date | May 4, 2004 |
| Priority date | — |
| Expiry date | Jul 2, 2021 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F9/7034
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
In a lithographic apparatus, a reference grating 11 mounted on the wafer table WT is illuminated with a measurement beam 20 incident in a direction independent of wafer table tilt. The diffraction orders are detected by detector 30 and used to determine the lateral shift in the wafer table resulting from a non-zero Abbe arm, and hence the Abbe arm, for calibration purposes. The detector 30 may be a detector also used for off-axis alignment of the wafer and wafer table.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.