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:
Mar. 20, 2018
Filed:
Jan. 25, 2017
International Business Machines Corporation, Armonk, NY (US);
Timothy Allan Brunner, Ridgefield, CT (US);
Martin Burkhardt, White Plains, NY (US);
INTERNATIONAL BUSINESS MACHINES CORPORATION, Armonk, NY (US);
Abstract
Obtaining optimal focus for exposing a photoresist in an EUV lithography with an EUV mask containing a pattern with an assist feature is disclosed. The EUV mask contains a repeating pattern, wherein the repeating pattern has two different pitches, i.e. a first pitch and a second pitch, and contains an assist feature between main features. Because the two different pitches have different focus offsets, the difference between linewidths of said gratings provides a calibration curve which is a measure of focus. The method for monitoring focus is performing a EUV exposure using a focus position with a pre-determined focus position as calibrated using the linewidth difference between the two gratings. The EUV mask for monitoring focus of present invention is applicable to both test and product masks.