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. 14, 1991
Filed:
Jul. 18, 1990
Kuniyoshi Yoshikawa, Tokyo, JP;
Kabushiki Kaisha Toshiba, Kawasaki, JP;
Abstract
A source diffusion region and a drain diffusion region are formed under an insulation film which is thicker than a gate insulation film and which isolates the adjacent channel regions from each other. The adjacent source and drain diffusion regions are isolated from each other by a trench which extends from the central portion of the thick insulation film to the interior of a semiconductor substrate. The trench is formed in a self-alignment manner with reference to the end portions of the adjacent floating gate electrodes, and the depth of this trench is determined so that the adjacent source and drain diffusion regions can be spaced sufficiently apart from each other. Since the trench reliably prevents punch-through and current leakage to the adjacent element, it is possible to remarkably reduce the cell size. Moreover, the peripheral circuits are not complicated since the functions of the source and drain regions are fixed.