How the common retention acceleration method of 3D NAND flash memory goes wrong?

Abstract

The reliability of solid-state drives (SSDs) has become increasingly important as SSDs are now widely applied in data centers. Retention error is a major source of impact on the reliability of SSDs. Even though the common practice in understanding the retention errors of an SSD is done by high-temperature baking processes, their characterization accuracy is not yet rigidly reviewed. In this paper, we first present how the common retention acceleration method goes wrong. Through a one-year study of 3D flash error behaviors, we found that the retention errors through baking with high temperatures have very different characteristics from the real long-retention errors. These differences come from the inherent structure and the materials of 3D NAND flash. Several findings regarding the retention errors characterized through baking are presented, followed by the analysis of the error behaviors. Finally, the retention errors of one year on 3D flash memory are provided with real data.