Inspection method and apparatus lithographic apparatus, lithographic processing cell, device manufacturing method and distance measuring system
US7869022B2 · kind B2 · utility
4Cited by
19References
17Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Jul 18, 2007 |
| Grant date | Jan 11, 2011 |
| Priority date | — |
| Expiry date | Jan 20, 2028 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B7/28
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A scatterometer has a focus sensor arranged to detect whether the target being measured is in a correct focal plane. A modulation is applied to a component of the focus sensor or the scatterometer such that a defocus as measured by the focus sensor varies according to a certain function. From knowledge of the modulation, the gain of the sensor can be calibrated.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.