On the Use of Strong BCH Codes for Improving Multilevel NAND Flash Memory Storage Capacity

This paper investigates the potential of using strong BCH codes to improve multilevel data-storage NAND Flash memory capacity. Current multilevel Flash memories store 2 bits in each cell. Further storage capacity may be achieved by increasing the number of storage levels per cell, which nevertheless will largely degrade the raw storage reliability. Based on a Gaussian-like memory cell threshold voltage distribution model and ASIC BCH decoder design results, we demonstrate that strong BCH codes can effectively enable the use of a larger number of storage levels per cell and hence improve the overall NAND Flash memory storage capacity up to 59.1% while maintaining the same cell programming time. Furthermore, we propose a scheme to leverage strong BCH codes to improve memory defect tolerance at the cost of increased cell programming time.