The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Aug. 12, 2008
Filed:
Oct. 18, 2005
Nicolaas Antonius Allegondus Johannes Van Asten, Breda, NL;
Oana Cristina Balan, Eindhoven, NL;
Luberthus Ouwehand, 's-Hertogenbosch, NL;
Machiel Jacobus Johannes Viguurs, Rosmalen, NL;
Alexander Charles Franciscus Anna Van Well, Best, NL;
Lun Kai Cheng, Krimpen aan den Ijssel, NL;
Huibert Blokland, Noordeloos, NL;
Elke Van Loenhout, Asten, NL;
Hans Baltus Bakker, Utrecht, NL;
Nicolaas Antonius Allegondus Johannes Van Asten, Breda, NL;
Oana Cristina Balan, Eindhoven, NL;
Luberthus Ouwehand, 's-Hertogenbosch, NL;
Machiel Jacobus Johannes Viguurs, Rosmalen, NL;
Alexander Charles Franciscus Anna Van Well, Best, NL;
Lun Kai Cheng, Krimpen aan den Ijssel, NL;
Huibert Blokland, Noordeloos, NL;
Elke Van Loenhout, Asten, NL;
Hans Baltus Bakker, Utrecht, NL;
ASML Netherlands B.V., Veldhoven, NL;
Abstract
The invention relates to a level sensor for determining a height of a substrate. The level sensor generates one or more measurement beam and directs the measurement beam to a measurement spot on the substrate and produces a reflected measurement beam. The level sensor also generates one or more reference beams. A detector detects both the reflected measurement beam and the reference beam, respectively, and produces a measurement signal and a reference signal, respectively, the measurement signal being indicative for the height at the measurement spot. A processor that receives these signals and corrects the measurement signal based on the reference signal. The level sensor has an optical arrangement in a predetermined area close to where the substrate is to be located. The measurement beam and the reference beam propagate along substantially equal optical paths of propagation in the predetermined area. The optical arrangement deviates the reference beam from the substantially equal optical paths of propagation in the predetermined area such that the at least one reference beam does not hit the substrate.