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. 07, 1992
Filed:
Jul. 19, 1991
Applicant:
Inventors:
Assignee:
Oki Electric Industry Co., Ltd., Tokyo, JP;
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
H01L / ;
U.S. Cl.
CPC ...
437203 ; 437924 ; 437947 ; 148 334 ; 148D / ;
Abstract
A wafer fabrication process uses peripheral etching to form grooves in a wafer substrate around the periphery of windows opened for dopant diffusion and alignment mark formation, and forms Si.sub.3 N.sub.4 tapers in the grooves. Although ultimately removed, the grooves create a pattern with nearly vertical sidewalls in the substrate which, when transferred to an epitaxial layer, forms wafer alignment marks with sharp edges. The process can be used to form wafer alignment marks having arbitrary patterns and can be adopted to improve the reliability of automatic alignment without the need to make new masks.