Focus detection apparatus for projection lithography system
US8760626B2 · kind B2 · utility
Assignees
Inventors
Key dates
| Filing date | May 4, 2012 |
| Grant date | Jun 24, 2014 |
| Priority date | — |
| Expiry date | Feb 14, 2033 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F9/7061
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
Disclosed is a focus detection apparatus for a projection lithography system. The apparatus includes: a laser; a focus optical unit configured to focusing the emitted laser beam; a force detection unit configured to reflect the focused laser beam at the backside; a position detection unit configured to detect variations in position of a light spot formed by the reflected laser beam, and output a strength signal indicating the strength of the interaction force between the force detection unit and the object; a differential amplifier configured to output a Z-direction differential signal based on the strength signal and a reference signal; a Z-direction feedback control unit configured to perform feedback control; and a scan signal generator configured to output a signal for controlling the movement of the stage in the XY plane. The focus detection apparatus has high precision, efficiency and process applicability.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.