Signal processing techniques for reliability improvement of sub-20NM NAND flash memory

The capacity of NAND flash memory has been continuously increased by adopting process technology scaling and multi-level cell (MLC) data coding. However, the reliability of stored data becomes a very important issue because the scaled feature size lowers the number of electrons at each floating-gate while increasing the cell-to-cell interference. In this paper, we review recent advances in signal processing techniques for reliability improvement of sub-20 nm NAND flash memory, which includes estimation of the threshold voltage distribution, cell-to-cell interference cancellation, and optimal multi-level memory sensing. We also present experimental results for the explained signal processing algorithms. Especially, we demonstrate the reliability improvement when combining all these techniaues.