The Noise and Random Telegraph Noise Characteristics in Floating-Gate nand Flash Memories

We have characterized low-frequency noise (LFN) such as 1/f noise and random telegraph noise (RTN) in a NAND flash memory cell string for the first time and shown its fundamental properties. The NAND flash memory cells showed specific LFN characteristics under various conditions such as bit-line bias, word-line bias of a selected cell, and pass bias of the unselected cells in the NAND string. Also, LFN was investigated with the program/erase (P/E) cycling of a cell or all cells in a string, and maximum threshold voltage fluctuation of several tens of millivolts after ~100 000 cycles at the 70-nm technology node was shown. Finally, we predicted the effects of LFN in sub-70-nm NAND flash memories.