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:
Jul. 02, 1991
Filed:
Sep. 28, 1989
Naoto Abe, Isehara, JP;
Shigeyuki Suda, Yokohama, JP;
Koji Uda, Yokohama, JP;
Hirohisa Ohta, Sagamihara, JP;
Noriyuki Nose, Machida, JP;
Canon Kabushiki Kaisha, Tokyo, JP;
Abstract
An alignment system for aligning a mask and a wafer into a predetermined positional relationship uses alignment marks provided on the mask and the water. In this system, light from a light source is directed to the alignment marks of the mask and the wafer and, then, the light from these alignment marks is detected by an accumulation type photoelectric converting device, for alignment of the mask and the wafer. The accumulation time of the photoelectric converting device is controlled to be sufficiently longer than or to be equal to a multiple, by an integral number, of the period of relative and natural vibration of the mask and the wafer. This makes it possible to reduce the effect of the relative vibration of the mask and the wafer upon the alignment result and, therefore, makes it possible to enhance the alignment precision.