Level sensor, lithographic apparatus and device manufacturing method
US7148494B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Dec 29, 2004 |
| Grant date | Dec 12, 2006 |
| Priority date | — |
| Expiry date | Jun 8, 2025 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F9/7034
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
The invention relates to a level sensor for use in a lithographic apparatus that determines a surface height of a substrate. The level sensor includes an emitter and a receiver, wherein the emitter is arranged to emit a signal directed to a predetermined position on the surface of the substrate, such that the signal is at least partially reflected by the substrate to render a reflected signal. The receiver is arranged to receive at least part of the reflected signal, and the level sensor is arranged to determine the surface height of the substrate with respect to the level sensor based on the emitted and received signal. The signal includes a pressure wave.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.