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. 15, 2019
Filed:
May. 23, 2014
Asml Netherlands B.v., Veldhoven, NL;
Hugo Augustinus Joseph Cramer, Eindhoven, NL;
Arie Jeffrey Den Boef, Waalre, NL;
Henricus Johannes Lambertus Megens, Waalre, NL;
Maurits Van Der Schaar, Eindhoven, NL;
Te-Chih Huang, Hsinchu, TW;
ASML Netherlands B.V., Veldhoven, NL;
Abstract
A method of determining a critical-dimension-related property, such as critical dimension (CD) or exposure dose, includes illuminating each of a plurality of periodic targets having different respective critical dimension biases, measuring intensity of radiation scattered by the targets, recognizing and extracting each grating from the image, determining a differential signal, and determining the CD-related property based on the differential signal, the CD biases and knowledge that the differential signal approximates to zero at a 1:1 line-to-space ratio of such periodic targets. Use of the determined CD-related property to control a lithography apparatus in lithographic processing of subsequent substrates. In order to use just two CD biases, a calibration may use measurements on a 'golden wafer' (i.e. a reference substrate) to determine the intensity gradient for each of the CD pairs, with known CDs. Alternatively, the calibration can be based upon simulation of the sensitivity of intensity gradient to CD.