Interference system and semiconductor exposure apparatus having the same
US6661522B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Jun 29, 2001 |
| Grant date | Dec 9, 2003 |
| Priority date | — |
| Expiry date | Sep 16, 2021 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01J9/02
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Disclosed is a Fizeau interference system for causing interference between reflection lights from a reflection surface and a semi-transmission surface, respectively, disposed along one and the same optical axis. The interference system includes a light source, an optical path difference applying optical system for dividing light from the light source into two lights and for re-combining them, and an interference optical system for causing reflection of the two lights passed through the optical path difference applying optical system, at corresponding one of the reflection surface and the semi-transmission surface, and to cause interference of them, wherein a difference &Dgr;F in optical path length of the light reflected by the reflection surface and with respect to the light reflected by the semi-transmission surface satisfies a relation |&Dgr;D−&Dgr;F|<&Dgr;L, where the optical path difference &Dgr;D between the two lights as applied by the optical path difference applying optical system &Dgr;D, and the coherence length of the light from the light source is &Dgr;L.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.