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. 09, 1976
Filed:
Mar. 07, 1975
Applicant:
Inventor:
Alan David White, Berkeley Heights, NJ (US);
Assignee:
Bell Telephone Laboratories, Incorporated, Murray Hill, NJ (US);
Attorneys:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
G01B / ; G02B / ;
U.S. Cl.
CPC ...
356172 ; 350 14 ; 3501 / ; 356114 ;
Abstract
In a semiconductor photolithographic mask alignment system, a unique bifocus element is included in the microscope for permitting simultaneous focusing on the mask and semiconductor wafer surface, even though the mask and wafer separation is greater than the microscope depth of field. The bifocus element is preferably located at the rear focal plane of the microscope objective and is designed to image, at the same location, light from the mask polarized in a first direction and light from the wafer polarized at right angles to the first direction.