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:
Dec. 06, 2016
Filed:
Mar. 11, 2013
Nikon Corporation, Chiyoda-ku, JP;
Michael Sogard, Menlo Park, CA (US);
Nikon Corporation, Tokyo, JP;
Abstract
In a lithography tool used in fabricating microelectronic devices, autofocus (AF) systems provide automatic image focusing before making exposures. To reduce production of erroneous results based on interaction of a beam of AF light with certain regions on lithographic substrates, a subject AF device has a sending unit and a receiving unit. The sending unit directs an AF light beam to the substrate, and the receiving unit receives AF light reflected from the substrate. The receiving unit has a system photodetector and a patterned optical element that receives AF light from the substrate and transmits a selected diffraction order(s) of said light. The system photodetector senses light of the selected diffraction order of reflected AF light while at least one additional photodetector detects divergent reflected AF light. Substrate areas exhibiting unusual amounts of divergent light may indicate a focus-error condition. The AF systems can be configured as fringe-projection or slit-projection AF systems.