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:
Feb. 05, 2013
Filed:
Mar. 31, 2011
Matthew R. Graham, San Diego, CA (US);
Olav Haugan, San Diego, CA (US);
William N. Partlo, San Diego, CA (US);
Matthew R. Graham, San Diego, CA (US);
Olav Haugan, San Diego, CA (US);
William N. Partlo, San Diego, CA (US);
Cymer, Inc., San Diego, CA (US);
Abstract
A method and apparatus for compensating for thermal effects on the focal spot of a lens used to focus a laser beam on a target material at an irradiation site in a laser produced plasma (LPP) extreme ultraviolet (EUV) light system is disclosed. The EUV energy output of the light system is measured at sample intervals as a proxy for the laser power. The thermal load on the focusing lens is estimated from the measured EUV power, the expected change in the focal length of the lens for the thermal load is calculated, and the lens position is adjusted to compensate for the calculated focal length change. The actual position of the lens may be determined and compared to its desired position, and adjusted to insure that it remains in the desired position.