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

Abstract

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.