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:
Jan. 15, 2002
Filed:
May. 31, 2000
Denso Corporation, Kariya, JP;
Abstract
In a nonvolatile semiconductor memory, a floating gate electrode is disposed above a silicon substrate between source and drain regions, through a tunnel film, and a control gate electrode is disposed above the floating gate electrode through an insulating film. The substrate is grounded and at least two negative voltages are respectively applied to the control gate electrode, so that a voltage is applied to the tunnel film. In these cases, charge retention properties are evaluated. The voltages applied to the control gate electrode are controlled so that the voltage applied to the tunnel film does not exceed a voltage applied to the tunnel film during a memory operation. A charge retention property when no voltage is applied across the control gate electrode and the substrate, i.e., when no voltage is externally applied to the tunnel film, is estimated by the charge retention properties when the two voltages are applied to the control gate electrode.