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:
Jul. 16, 2019
Filed:
Dec. 04, 2017
Asml Netherlands B.v., Veldhoven, NL;
Nitesh Pandey, Eindhoven, NL;
Zili Zhou, Eindhoven, NL;
ASML Netherlands B.V., Veldhoven, NL;
Abstract
Methods of measuring a target formed by a lithographic process, a metrology apparatus and a polarizer assembly are disclosed. The target comprises a layered structure having a first periodic structure in a first layer and a second periodic structure in a second layer. The target is illuminated with polarized measurement radiation. Zeroth order scattered radiation from the target is detected. An asymmetry in the first periodic structure is derived using the detected zeroth order scattered radiation from the target. A separation between the first layer and the second layer is such that the detected zeroth order scattered radiation is independent of overlay error between the first periodic structure and the second periodic structure. The derived asymmetry in the first periodic structure is used to derive the correct overlay value between the first periodic structure and the second periodic structure.