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:
Feb. 23, 1988
Filed:
Oct. 29, 1985
Takashi Matsumoto, Kawasaki, JP;
Motoo Nakano, Yokohama, JP;
Fujitsu Limited, Kawasaki, JP;
Abstract
An improved electrically alterable read-only memory (EAROM) is offered by the method of the invention, the memory device comprising a floating gate type field effect transistor in which a part of the floating gate and a part of the drain region formed in a silicon substrate overlap. According to the method, impurity atoms are ion implanted into a part of a region where the drain region is to be formed through an insulation layer of silicon dioxide on the region. Thereafter, the insulation layer through which ion implantation was carried out is removed and a fresh insulation layer of silicon dioxide is formed where the old insulation layer was removed. By this method, a good, thin insulation film is fabricated. By virtue of the fresh insulation layer devoid of trap centers which trap electric charges, the insulation layer is free from defects that interrupt flow of electrons required for writing or erasing of information.