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. 04, 1997
Filed:
Dec. 06, 1994
Vincent L Fong, Cuppertino, CA (US);
National Semiconductor Corporation, Santa Clara, CA (US);
Abstract
A flash memory system and method for providing an array of erased flash memory cells having a reduced dispersion of erased threshold voltages. The cells of the system are erased in bulk, preferably utilizing some form of cold electron injection, and the cells are tested to determine whether the erased threshold voltage falls between a predetermined target maximum threshold voltage and a predetermined target minimum threshold voltage. In the event one or more cells has been over erased so that the measured threshold voltage is less than the target minimum values, all of the cells are lightly programmed so as to increase the actual threshold voltage. The light programming is repeated until all of the cells have an actual threshold voltage that exceeds the target minimum but is less than the target maximum.