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. 04, 2003
Filed:
Jul. 27, 2000
Edward W. Conrad, Jeffersonville, VT (US);
Paul D. Sonntag, Colchester, VT (US);
Arthur C. Winslow, Essex Junction, VT (US);
International Business Machines Corporation, Armonk, NY (US);
Abstract
Photolithography tools have alignment systems for aligning a level to be printed with a level already on the wafer. Commonly a photolithography tool has several alignment systems Also, wafers may have several alignment marks, and the various alignment systems may be capable of reading several of the alignment marks. The present invention provides a method of selecting the alignment system-alignment mark combination that gives the most accurate alignment to a previous level. The inventors found that residual errors provide a metric by which to evaluate alignment system-alignment mark combinations. The combination with the least residual error is selected. Alternatively data for actual overlay measurements is compared with alignment data for each alignment system-alignment mark combination, and the combination that has the best correlation to the overlay data is selected.