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. 19, 1996
Filed:
Jun. 28, 1995
Applicant:
Inventors:
Assignee:
United Microelectronics Corporation, Hsinchu, TW;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
H01L / ;
U.S. Cl.
CPC ...
437 48 ; 437 52 ; 437924 ;
Abstract
A process for coding and code marking a read-only memory device makes use of a buffer layer, such as silicon nitrides (Si.sub.3 N.sub.4) or silicon oxynitrides (SiN.sub.x O.sub.y), to form a code mark therein. Owing to the etching selectivity between the buffer layer and an underlying layer, for example, silicon oxides, the programmed region not covered by the word lines will not suffer from etching damage while forming the code mark. Therefore, the coding and code marking process can employ the same mask layer, but without the need for two different photomasking procedures to implement code programming and identification code marking.