A Stride-Away Programming Scheme to Resolve Crash Recoverability and Data Readability Issues of Multi-Level-Cell Flash Memory

The multi-level-cell (MLC) technique is widely adopted by flash memory vendors to increase the chip capacity and to lower the cost, but also results in serious reliability problems. To improve the reliability of MLC flash memory, conventional MLC programming approaches tend to adopt the incremental step pulse program (ISPP) procedure and N-shape programming sequence to program the MLC flash cells. These approaches can improve the reliability of MLC flash memory by reducing the effects of programming disturbance; however, it could further result in the crash recoverability and data readability issues. To ensure the crash recoverability, the backup procedure is necessary for supporting the sudden-power-off-recovery function, and it is typically adopted to avoid data corruption before programming TLC flash pages. Such a backup procedure would further result in the bad programming performance. This motivates this work to explore the innovative programming design for resolving crash recoverability and data readability issues of multi-level-cell flash memory. Thus, to eliminate the negative effects caused by the conventional programming methods, this paper presents and realizes a stride-away MLC programming scheme. The proposed stride-away programming scheme could resolve both the crash recoverability and the data readability issues without the adoption of backup procedures. As a result, the programming performance can also be improved with the proposed stride-away programming scheme. A series of experiments were conducted to evaluate the capability of the proposed design, for which we prove that the proposed scheme can boost the write performance up to 1.8 times.