Programming and Program-Verification Methods for Low-Voltage Flash Memories Using a Sector Programming Scheme

Katsutaka KIMURA
Toshihiro TANAKA
Masataka KATO
Keisuke OGURA
Hitoshi KUME

IEICE TRANSACTIONS on Electronics   Vol.E78-C    No.7    pp.832-837
Publication Date: 1995/07/25
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on LSI Memory Device, Circuit, Architecture and Application Technologies for Multimedia Age)
flash memory,  program,  erase,  Fowler-Nordheim tunneling,  sector,  

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Programming and program-verification methods for low-voltage flash memories using the Fowler-Nordheim tunneling mechanism for both programming and erasure are described. In these memories, a great many memory cells on a selected word line, such as 512-bytes worth of cells, are programmed at the same time for high-speed programming. The bit-by-bit programming/verification method can precisely control threshold-voltage deviation of programmed memory cells on the selected word line for low voltage operation. By using an internal program-end detection circuit, the completion of program mode can be checked for in one clock cycle, without reading out 512-bytes of data from the memory chip to the external controller. Moreover, the variable pulse-width programming method reduces the total number of verifications.