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:
Aug. 19, 2008
Filed:
Mar. 23, 2006
Jeffrey W. Lutze, San Jose, CA (US);
Jian Chen, San Jose, CA (US);
Yan LI, Milpitas, CA (US);
Kazunori Kanebako, Yokohama, JP;
Tomoharu Tanaka, Yokohama, JP;
Jeffrey W. Lutze, San Jose, CA (US);
Jian Chen, San Jose, CA (US);
Yan Li, Milpitas, CA (US);
Kazunori Kanebako, Yokohama, JP;
Tomoharu Tanaka, Yokohama, JP;
SanDisk Corporation, Milpitas, CA (US);
Abstract
A number of methods for identifying cells with poor subthreshold slope and reduced transconductance. A first set of techniques focuses on the poor subthreshold behavior of degraded storage elements by cycling cells and then programming them to a state above the ground state and the reading them with a control gate voltage below the threshold voltage of this state to see if they still conduct. A second set of embodiments focuses on weak transconductance behavior by reading programmed cells with a control gate voltage well above the threshold voltage. A third set of embodiments alters the voltage levels at the source-drain regions of the storage elements. The current-voltage curve of a good storage element is relatively stable under this shift in bias conditions, while degraded elements exhibit a larger shift. The amount of shift can be used to differentiate the good elements from the bad.