A Design of Constant-Charge-Injection Programming Scheme for AG-AND Flash Memories Using Array-Level Analytical Model

Shinya KAJIYAMA  Ken'ichiro SONODA  Kazuo OTSUGA  Hideaki KURATA  Kiyoshi ISHIKAWA  

Publication
IEICE TRANSACTIONS on Electronics   Vol.E91-C   No.4   pp.526-533
Publication Date: 2008/04/01
Online ISSN: 1745-1353
DOI: 10.1093/ietele/e91-c.4.526
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Advanced Technologies in Digital LSIs and Memories)
Category: 
Keyword: 
flash memory,  AG-AND,  modeling,  constant-charge-injection programming,  lucky electron model,  

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Summary: 
A design methodology optimizing constant-charge-injection programming (CCIP) for assist-gate (AG)-AND flash memories is proposed. Transient circuit simulations using an array-level model including lucky electron model (LEM) current source describing hot electron physics enables a concept design over the whole memory-string in advance of wafer manufacturing. The dynamic programming behaviors of various CCIP sequences, obtained by circuit simulations using the model is verified with the measurement results of 90-nm AG-AND flash memory, and we confirmed that the simulation results sufficiently agree with the measurement, considering the simulation results give optimum bias AG voltage approximately within 0.2 V error. Then, we have applied the model to a conceptual design and have obtained optimum bit line capacitance value and CCIP sequence those are the most important issues involved in high-throughput programming for an AG-AND array.