NAND Flash Cell의 Endurance 열화 특성 분석

In this paper, we focus on analyzing the endurance degradation characteristics at different WLs in 2X floating-gate (FG) NAND flash cell. A FG NAND flash cell string has 64 WLs, 2 dummy WLs, 1 GSL and 1 SSL, respectively. To observe the memory cell degradation by the program/erase cycle, we measure the cell current of 64 cells in a string after each cycling and then perform comparative analysis. As a result, the edge (WL0, WL63) cells in a string show the similar degradation characteristics, but, WL30 cell degrades more than the edge cells at erase operation.