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. 07, 1995
Filed:
Mar. 31, 1994
Toshiyuki Hayakawa, Yokohama, JP;
Ryouhei Kirisawa, Kitakami, JP;
Kabushiki Kaisha Toshiba, Kanagawa, JP;
Abstract
A non-volatile semiconductor memory device includes NAND type memory cells arranged in a matrix pattern over a semiconductor substrate and channel stopper layers, provided on the substrate, for separating adjacent NAND type memory cells. Each NAND type memory cell includes memory cell transistors having drains and sources mutually connected in series, a source side select transistor connected to a source of one end transistor of the memory cell transistors, and a drain side select transistor connected to a drain of the other end transistor of the memory cell transistors. Each channel stopper layer has a first layer portion for separating the source side select transistors and a second layer portion for separating the memory cell transistors. Impurity concentration of the first layer portion is lower than that of the second layer portion.