A High-Speed BE-SONOS NAND Flash Utilizing the Field-Enhancement Effect of FinFET

Theoretical calculation indicates that when the fin width is comparable to the EOT of the ONO, the bottom oxide electric field around the fin tip is significantly increased, resulting in the enhanced program/erase efficiency. We also discover that the non-uniform injection along the fin changes DC characteristics (S.S. and g_m) during program/erase, and the effective channel width of FinFET SONOS is only around the fin tip. We integrate BE-SONOS in a body-tied FinFET structure with a very small fin width (<20 nm), and demonstrate a high-speed NAND Flash (<20 musec programming time and <2 msec erasing time for a 5 V memory window). The present work provides not only physical insights into the operation mechanisms of FinFET SONOS-type devices, but also a new design method for high-speed NAND Flash.