title: Reliability Degeneration Mechanisms of the 20-nm Flash Memories Due to the Word Line Stress.
abstract: The electrical characteristics of NAND flash memories with a high-k dielectric layer were simulated by using a full three-dimensional technology computer-aided design simulator. The occurrence rate of the errors in the flash memories increases with increasing program/erase cycles. To verify the word line stress effect, electron density in the floating gate of target cell and non-target cell, the drain current in the channel of non-target cell and depletion region of the non-target cell were simulated as a function of program/erase cycle, for various floating gate thicknesses. The electron density in the floating gate became decreased with increasing program/erase cycles. The reliability degradation occured by the increased depletion region at the bottom of the polysilicon floating gate in the continued program/erase cycle situation due to the word line stress. The degradation mechanisms for the program characteristics of 20-nm NAND flash memories were clarified by examining electron density, darin current and depletion region.
authors.forename: Hyun Soo
authors.initials: HS
authors.lastname: Jung
authors.forename: Ju Tae
authors.initials: JT
authors.lastname: Ryu
authors.forename: Keon-Ho
authors.initials: KH
authors.lastname: Yoo
authors.forename: T W
authors.initials: TW
authors.lastname: Kim