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:
Apr. 25, 2017
Filed:
Aug. 27, 2015
Vrije Universiteit Amsterdam, Amsterdam, NL;
Universiteit Van Amsterdam, Amsterdam, NL;
Stichting Voor Fundamenteel Onderzoek Der Materie, Utrecht, NL;
Asml Netherlands B.v., Veldhoven, NL;
Arie Jeffrey Den Boef, Waalre, NL;
Simon Gijsbert Josephus Mathijssen, Rosmalen, NL;
Nitesh Pandey, Eindhoven, NL;
Stefan Michiel Witte, Hoofddorp, NL;
Kjeld Eikema, Amsterdam, NL;
ASML Netherlands B.V., Veldhoven, NL;
Abstract
Metrology targets are formed on a substrate (W) by a lithographic process. A target (T) comprising one or more grating structures is illuminated with spatially coherent radiation under different conditions. Radiation () diffracted by from said target area interferes with reference radiation () interferes with to form an interference pattern at an image detector (). One or more images of said interference pattern are captured. From the captured image(s) and from knowledge of the reference radiation a complex field of the collected scattered radiation at the detector. A synthetic radiometric image () of radiation diffracted by each grating is calculated from the complex field. From the synthetic radiometric images (') of opposite portions of a diffractions spectrum of the grating, a measure of asymmetry in the grating is obtained. Using suitable targets, overlay and other performance parameters of the lithographic process can be calculated from the measured asymmetry.