A Temperature-Aware Reliability Enhancement Strategy for 3-D Charge-Trap Flash Memory

Compared to the conventional planar flash memory, advanced 3-D flash memory adopts charge-trap technology that can significantly enhance cell density and storage capacity. Despite these advantages, 3-D charge-trap flash memory brings several new challenges. First, charge-trap flash is sensitive to temperature. Recent studies demonstrate that, the high temperature will incur both charge loss and retention degradation. This issue does not happen in 2-D flash memory which adopts floating gate technology. Second, current 3-D charge-trap flash integrates the extra large capacity physical block, and each block contains over 1024 physical pages. The large-capacity block infrastructure will cause extra garbage collection overhead, which makes the thermal issue more complicated. This paper presents TempCure, a temperature-aware reliability enhancement strategy for 3-D charge-trap flash memory. TempCure is a novel hardware and file system interface that can transparently allocate physical space based on the temperature status. TempCure adopts two reliability enhancement strategies, temperature mining and block allotment, to prevent the generation of hotspots and enhance the data integrity of 3-D flash memory. We conduct a set of experiments using standard benchmarks. Experimental results show that TempCure can effectively reduce the peak temperature and block erase counts with negligible timing overhead in comparison with representative schemes.