A new read method suppressing effect of random telegraph noise in NAND flash memory by using hysteretic characteristic

摘要

A new read method which suppresses the effect of read current fluctuation due to random telegraph noise was proposed to reduce read error in NAND flash memory by using hysteretic characteristic. By controlling the amplitude and polarity of a word-line (WL) bias applied to the gate of a selected cell in a cell string, we can predict stochastically RTN event at μsec time range. From measured transient bit-line current and sampled 1k times IBL in μsec range, we could verify that proposed method is effective in reducing significantly an error in reading a cell state. The hysteretic effect was characterized as parameters of the trap energy and temperature (T).