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:
Nov. 19, 2019
Filed:
May. 01, 2018
Asml Netherlands B.v., Veldhoven, NL;
Murat Bozkurt, Uden, NL;
Maurits Van Der Schaar, Eindhoven, NL;
Patrick Warnaar, Tilburg, NL;
Martin Jacobus Johan Jak, 's-Hertogenbosch, NL;
Mohammadreza Hajiahmadi, Rotterdam, NL;
Grzegorz Grzela, Eindhoven, NL;
Lukasz Jerzy Macht, Eindhoven, NL;
ASML Netherlands B.V., Veldhoven, NL;
Abstract
An overlay metrology target () contains a plurality of overlay gratings (-) formed by lithography. First diffraction signals (()) are obtained from the target, and first asymmetry values (As) for the target structures are derived. Second diffraction signals (()) are obtained from the target, and second asymmetry values (As') are derived. The first and second diffraction signals are obtained using different capture conditions and/or different designs of target structures and/or bias values. The first asymmetry signals and the second asymmetry signals are used to solve equations and obtain a measurement of overlay error. The calculation of overlay error makes no assumption whether asymmetry in a given target structure results from overlay in the first direction, in a second direction or in both directions. With a suitable bias scheme the method allows overlay and other asymmetry-related properties to be measured accurately, even in the presence of two-dimensional overlay structure.