Error Patterns in MLC NAND Flash Memory

23 Jun 2015

Error Patterns in MLC NAND Flash Memory: Measurement, Characterization, and Analysis on DATE 2012.

This paper study the Error Patterns in MLC NAND Flash Memory. The MLC has multiple state indicated by threshold voltage of a given cell.

mlc_flash

Types of Errors

  1. Retention Error – happens when the data stored in a cell changes over time.
  2. Program Interference Error – happens when the data stored in a page changes (unintentionally) while a neighbouring page is being programmed due to parasitic capacitance-coupling.
  3. Read Error – happens when the data stored in a cell changes as a neighboring cell on the same string is read over and over.
  4. Erase Error – happens when an erase operation fails to reset the cells to the erased state

As shown in the results, the retention error and program interference error are more dominant than others.

retention_error

Majority of the retention error are 00 -> 01 and 01 -> 10. As shown in the first figure, the retention error occurs when the cell lost electric.

Majority of the program interference error are 11 -> 10 and 10 -> 01. As shown in the first figure, the program interference error occurs when the cell is over charged.