Program and read methods with offset in quad-level-cell NAND design

3D QLC (Quad-Level-Cell) NAND technology with 16 voltage levels per cell will be one of the next generation memory technologies after 3D TLC (Triple Level Cell) NAND flash succeeded. Besides, program algorithm for 16 voltage levels is studied in this paper, the important read algorithms are investigated because the data errors of QLC device will be easily generated due to power loss, program distribute, etc. The read method with offset and soft message generation for Low Density Parity Check (LDPC) Belief Propagation (BP) soft-decision decoding are presented.