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:
Jan. 19, 2016
Filed:
Jul. 14, 2014
Asml Netherlands B.v., Veldhoven, NL;
Rong Liu, San Diego, CA (US);
Robert J. Rafac, Encinitas, CA (US);
David Wayne Myers, Poway, CA (US);
Robert A. Bergstedt, Carlsbad, CA (US);
Paul Alexander McKenzie, Encinitas, CA (US);
ASML Netherlands B.V., Veldhoven, NL;
Abstract
In a laser-produced plasma (LPP) extreme ultraviolet (EUV) system, laser pulses are used to produce EUV light. To determine the energy of individual laser pulses, a photoelectromagnetic (PEM) detector is calibrated to a power meter using a calibration coefficient. When measuring a unitary laser beam comprising pulses of a single wavelength, the calibration coefficient is calculated based on a burst of the pulses. A combined laser beam has main pulses of a first wavelength alternating with pre-pulses pulses of a second wavelength. To calculate the energy of the main pulses in the combined laser beam, the calibration coefficient calculated for a unitary laser beam of the main pulses is used. To calculate the energy of the pre-pulses in the combined laser beam, a new calibration coefficient is calculated. When the calculated energy values drift beyond a pre-defined threshold, the calibration coefficients are recalculated.