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. 25, 2000
Filed:
Mar. 18, 1997
Yasushi Sato, Tokyo, JP;
Masao Tsujimoto, Tokyo, JP;
Oki Electric Industry Co., Ltd., Tokyo, JP;
Abstract
The present invention provides a method of evaluating a tunnel insulating film of a first MOS FET having a semiconductor substrate, a control gate, a floating gate and a tunnel insulating film formed between the semiconductor substrate and the floating gate which is injected with electrons from the semiconductor substrate by applying a direct current voltage to the control gate. The method is achieved by preparing a second MOS FET having a tunnel insulating film formed on a semiconductor substrate in the same batch process of forming the tunnel insulating film in the first MOS FET, measuring a subthreshold swing of the second MOS FET, applying a direct current electric field to the tunnel insulating film in the second MOS FET for a predetermined time, remeasuring the subthreshold swing of the second MOS FET, and evaluating the tunnel insulating film in the first MOS FET by using a change of the subthreshold swing before and after the applying step.