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:
Apr. 20, 2004
Filed:
May. 31, 2002
Macronix International Co., Taiwan, TW;
Abstract
A method of fabricating a semiconductor memory device, particularly a mask ROM. A sacrificial oxide layer is formed on a silicon substrate and then a photoresist layer is formed on the sacrificial oxide layer. The photoresist layer is patterned to form a plurality of openings where bit lines are to extend respectively. Taking the patterned photoresist layer as a mask, arsenic ions are implanted into the silicon substrate through the openings and then boron ions are implanted into the silicon substrate through the openings. The implantation depth of boron ions are deeper than arsenic ions. The photoresist layer and the sacrificial oxide layer are removed after implantation. A gate oxide and a field oxide are grown simultaneously on the non-implanted and the implanted regions of the semiconductor layers respectively and a gate conductive layer is deposited on the silicon substrate.