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:
Oct. 08, 2002
Filed:
Jun. 17, 1999
Applicant:
Inventors:
Chris Gould, Stanfordville, NY (US);
K. Paul Muller, Wappingers Falls, NY (US);
V. C. Jai Prakash, Beacon, NY (US);
Robert van den Berg, Hopewell Junction, NY (US);
Assignee:
International Business Machines Corporation, Armonk, NY (US);
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
G06K 9/36 ;
U.S. Cl.
CPC ...
G06K 9/36 ;
Abstract
A process for measuring the alignment of different layers on a semiconductor wafer ( ) includes forming repetitive alignment marks ( ) having substantially the same period on the different layers on the wafer ( ). The images of the overlay alignment marks ( ) are converted from space domain to frequency domain through Fourier transformations. The alignment measurements are performed by calculating the phase difference between the images corresponding to the repetitive patterns ( ) on different layers.