Reliability Impacts Among Neighboring Wordlines on 3D QLC NAND Flash

3D Quad-level Cell (QLC) NAND flash memory is widely used due to its low cost and high density. However, the use of 3D stacking technology has raised severe reliability concerns and the interaction among neighbor cells becomes predominantly heavy. This paper studies the reliability impacts among neighboring wordlines (WLs) in 3D QLC flash chips, especially with data patterns. We performed systematic experiments on different 3D flash models under various conditions. The evaluation results present that the reliability of a victim WL is affected by what is programmed to the neighbor WLs. The impacts also vary with the data programmed on the victim WL. Additionally, the neighbor WLs present similar behaviors over data patterns programmed on them and the impacts vary with different locations. Some phenomena observed are manifested differently in various flash models, providing a foundation for future reliability optimization in high-density 3D flash blocks.