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:
Sep. 17, 1996
Filed:
Sep. 30, 1994
Makoto Takizawa, Yokohama, JP;
Kazunori Kanebako, Yokohama, JP;
Kabushiki Kaisha Toshiba, Kawasaki, JP;
Abstract
A mask ROM for storing multi-value data has a memory cell comprising a primary conductive region formed by a first conductive type semiconductor, a source region formed in the primary conductive region by a second conductive type semiconductor, a drain region formed in the primary conductive region by the second conductive type semiconductor, a channel region adjacently formed with the source region and the drain region, a gate insulation layer formed on the channel region, and a gate electrode formed on the gate insulation layer, wherein the channel region or the gate electrode is divided into a plurality of parts, each divided part having a different layer thickness from the other or a different transmissivity for ion injection, so as to form a ROM.