Improving Multi-Level NAND Flash Memory Storage Reliability Using Concatenated BCH-TCM Coding

By storing more than one bit in each memory cell, Multi-Level per Cell (MLC) NAND flash memories are dominating global flash memory market due to their appealing storage density advantage. However, continuous technology scaling makes MLC NAND flash memories increasingly subject to worse raw storage reliability. This paper presents a memory fault tolerance design solution geared to MLC NAND flash memories. The basic idea is to concatenate Trellis Coded Modulation (TCM) with an outer BCH code, which can greatly improve the error correction performance compared with the current design practice that uses BCH codes only.