Achieving Defect-Free Multilevel 3D Flash Memories with One-Shot Program Design

To store the desired data on MLC and TLC flash memories, the conventional programming strategies need to divide a fixed range of threshold voltage (Vt) window into several parts. The narrowly partitioned Vt window in turn limits the design of programming strategy and becomes the main reason to cause flash-memory defects, i.e., the longer read/write latency and worse data reliability. This motivates this work to explore the innovative programming design for solving the flash-memory defects. Thus, to achieve the defect-free 3D NAND flash memory, this paper presents and realizes a one-shot program design to significantly eliminate the negative impacts caused by conventional programming strategies. The proposed one-shot program design includes two strategies, i.e., prophetic and classification programming, for MLC flash memories, and the idea is extended to TLC flash memories. The measurement results show that it can accelerate programming speed by 31x and reduce RBER by 1000x for the MLC flash memory, and it can broaden the available window of threshold voltage up to 5.1x for the TLC flash memory.