Abstract: In general, as the number of program/erase cycles increases over time, number of errors also increases in NAND flash memories. Hence, these memories suffer from write/read disturbs, data retention errors, bad block accumulation. Also, reliability of MLC memory is lower due to reduced gap between adjacent threshold levels. This causes for continuous scaling down of NAND flash memories. In order to improve the unwavering quality and performance of the chip, combinations of techniques are proposed in the paper. The aim of the paper is to prevent the data from being stored in a block that is bad to reduce power consumption and to place the data in the exact location rather than being stored in an equivalent address according to the mapping table to improve the performance of the memory using coding theory(Error Correction Code).Thereby, realizing higher efficiency, reliability and support longer lifetimes of NAND flash memory.
Keywords: NAND, retention error, unwavering, threshold.