Simulation Study on Dependence of Channel Potential Self-Boosting on Device Scale and Doping Concentration in 2-D and 3-D NAND-Type Flash Memory Devices

Seongjae CHO  Jung Hoon LEE  Yoon KIM  Jang-Gn YUN  Hyungcheol SHIN  Byung-Gook PARK  

Publication
IEICE TRANSACTIONS on Electronics   Vol.E93-C   No.5   pp.596-601
Publication Date: 2010/05/01
Online ISSN: 1745-1353
DOI: 10.1587/transele.E93.C.596
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Fundamentals and Applications of Advanced Semiconductor Devices)
Category: Flash/Advanced Memory
Keyword: 
NAND,  flash memory,  program inhibition,  self-boosting,  FinFET,  device simulation,  

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Summary: 
In performing the program operation of the NAND-type flash memory array, the program-inhibited cell is applied by a positive voltage at the gate, i.e., word-line (WL) on the floating channel while the program cell is applied by program voltage as the two ends, drain select line (DSL) and source select line (SSL), are turned on with grounded bit-line (BL). In this manner, the self-boosting of silicon channel to avoid unwanted program operation is made possible. As the flash memory device is aggressively scaled down and the channel doping concentration is increased accordingly, the coupling phenomena among WL, floating gate (FG)/storage node, and silicon channel, which are crucial factors in the self-boosting scheme, should be investigated more thoroughly. In this work, the dependences of self-boosting of channel potential on channel length and doping concentration in the 2-D conventional planar and 3-D FinFET NAND-type flash memory devices based on bulk-silicon are investigated by both 2-D and 3-D numerical device simulations. Since there hardly exists realistic ways of measuring the channel potential by physical probing, the series of simulation works are believed to offer practical insights in the variation of channel potential inside a flash memory device.