A Novel Programming Method Using a Reverse Polarity Pulse in Flash EEPROMs

Hirohisa IIZUKA  Tetsuo ENDOH  Seiichi ARITOME  Riichiro SHIROTA  Fujio MASUOKA  

IEICE TRANSACTIONS on Electronics   Vol.E79-C   No.6   pp.832-835
Publication Date: 1996/06/25
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on ULSI Memory Technology)
Category: Nonvolatile memories
flash EEPROM,  oxide leakage current,  hole trap,  reverse polarity pulse,  read disturb,  

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The data retention characteristics for Flash EEPROM degrade after a large number of write and erase cycles due to the increase of the tunnel oxide leakage current. This paper proposes a new write/erase method which uses a reverse polarity pulse after each erase pulse. By using this method, the leakage current can be suppressed. As a result, the read disturb time after 105cycles write/erase operation is more than 10 times longer in comparison with that of the conventional method. Moreover, using this method, the endurance cycle dependence of the threshold voltage after write and erase operation is also drastically improved.