Initialize and Weak-Program Erasing Scheme for High-Performance and High-Reliability Ferroelectric NAND Flash Solid-State Drive

Kousuke MIYAJI  Ryoji YAJIMA  Teruyoshi HATANAKA  Mitsue TAKAHASHI  Shigeki SAKAI  Ken TAKEUCHI  

Publication
IEICE TRANSACTIONS on Electronics   Vol.E95-C   No.4   pp.609-616
Publication Date: 2012/04/01
Online ISSN: 1745-1353
DOI: 10.1587/transele.E95.C.609
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Solid-State Circuit Design – Architecture, Circuit, Device and Design Methodology)
Category: 
Keyword: 
ferroelectric FET,  NAND flash memory,  solid-state drive,  bit-by-bit verifying technique,  history effect,  

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Summary: 
Initialize and weak-program erasing scheme is proposed to achieve high-performance and high-reliability Ferroelectric (Fe-) NAND flash solid-state drive (SSD). Bit-by-bit erase VTH control is achieved by the proposed erasing scheme and history effects in Fe-NAND is also suppressed. History effects change the future erase VTH shift characteristics by the past program voltage. The proposed erasing scheme decreases VTH shift variation due to history effects from ±40% to ±2% and the erase VTH distribution width is reduced from over 0.4 V to 0.045 V. As a result, the read and VPASS disturbance decrease by 42% and 37%, respectively. The proposed erasing scheme is immune to VTH variations and voltage stress. The proposed erasing scheme also suppresses the power and bandwidth degradation of SSD.