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:
Oct. 18, 1988
Filed:
Mar. 23, 1987
Applicant:
Inventor:
Pak K Leung, Kanata, CA;
Assignee:
Northern Telecom Limited, Montreal, CA;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
G03C / ;
U.S. Cl.
CPC ...
430311 ; 430 30 ; 356237 ; 356394 ;
Abstract
A method of detecting opaque defects on a reticle used to define die patterns during semiconductor device fabrication in which a comparison is made of reflected light levels between an image die containing the developed photo-sensitive resist of a top layer with a reference die which contains only previously formed layers. The comparison is limited to areas of the device where there is no image pattern formed by the resist. A defect is detected whenever there is a difference in the recorded levels detected during the comparison.