Effect of Read Disturb on Incomplete Blocks in MLC NAND Flash Arrays

The effect of read disturb on partially programmed blocks of MLC NAND is evaluated using experimental data from 2y-, 1y-and 1x-nm Flash memory devices. We demonstrate that when a partially programmed block is exposed to a large number of reads before it is finalized in terms of page programming, the remaining pages will exhibit a significant bit error-rate (BER) increase. The page-BER is characterized in terms of program-erase cycles and read cycles and is further analyzed based on the programmed threshold voltage distributions. The impact of the page programming algorithm is also discussed.