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:
Nov. 21, 1995
Filed:
Jul. 01, 1994
Whitson G Waldo, III, Hutto, TX (US);
Gong Chen, Madison, WI (US);
Franco Cerrina, Madison, WI (US);
Motorola, Inc., Schaumburg, IL (US);
Abstract
A method for alignment in photolithographic processes includes providing a target (31) comprising features having a characteristic spatial period (P). An optical image of the target is captured, and components (33) of the image lacking the characteristic spatial period (P) are filtered out. The filtered image is integrated in the direction of the characteristic period (P) thereby creating an alignment signal (40). The alignment signal (40) is a symmetric signal which correlates to the symmetric target (31). A linear centroid (41) of the alignment signal is located, and corresponds to the precise linear center of the target (31). Consequently, the linear location of an object (10) upon which the target (31) is printed, can be accurately located. The process is performed in two perpendicular dimensions (x,y) so that the object (10) can be precisely located and positioned in two dimensions (x,y).