High-to-Low Flippling (HLF) Coding Strategy in Triple-levell-cell (TLC) 3D NAND Flash Memory to Construct Reliable Image Storages

In order to construct highly reliable image storages with triple-level-cell (TLC) 3D charge-trap NAND flash memory, the image coding strategy is optimized by taking the memory properties into account. Firstly, error bits at different program states are studied on the NAND chip tester, and then we propose a high-to-low flipping (HLF) coding scheme to suppress bit-error-rate (BER). It is found that the HLF coding scheme can effectively suppress BER during the long-time retention, which is important to prolong the lifetime of image storages. Specially, in the fresh block, BER is reduced to x63.9% similar to 44.9%; while in the 2000 PE cycled block, BER can be reduced to x34.9% similar to 15.6%.