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:
May. 06, 2003
Filed:
Jul. 10, 2002
Jen-Chuan Pan, Hsinchu, TW;
Macronix International Co., Ltd., Hsinchu, TW;
Abstract
A method for fabricating a mask ROM device is described. The method includes forming a buried drain region in a substrate and forming a thick oxide layer on the substrate. Perpendicular to the direction of the buried drain region, a bar-shaped silicon nitride layer is formed on the thick oxide layer. A portion of the thick oxide layer is then removed to expose the substrate, followed by forming a gate oxide layer on the exposed substrate surface for forming a plurality of coded memory cells, wherein the coded memory cells with a gate oxide layer corresponds to a logic state “1” while the code memory cells with a thick silicon oxide layer corresponds to a logic state “0”. A polysilicon layer is then formed on the substrate, followed by back-etching the polysilicon layer to expose the bar-shaped silicon nitride layer. After this, the bar-shaped silicon nitride layer is removed.