Characterization of cell to cell interference in TANOS NAND flash memory

Abstract

Cell-to-cell interference in charge trap based TANOS (Tantalum-Alumina-Nitride-Oxide-Silicon) NAND flash memory was investigated. Bit-line (B/L) interference is larger than word-line (W/L) one, which means that the channel coupling by adjacent program string to inhibit string gives larger effect than capacitive coupling to adjacent nitride storage nodes along the string. By separating the total Vth shift into each component, the channel coupling between inhibit and program strings is a main cause to make a large Vth shift. The interference between adjacent W/Ls was also observed and expected to be increased with scale-down. The read operation by applying proper read voltage on adjacent cells can alleviate the unwanted Vth shift from adjacent W/Ls to some extent.