Experimental Verification and Analysis of the Acceleration Factor Model for 3-D nand Flash Memory

With the increasing density of flash memory, its service life is declining. As the most important technical index of a flash device, flash retention parameters often need to consume a substantial amount of time to be tested. With a view toward reducing the test period, the most popular method currently is to speedup the retention loss of flash memory at high temperatures. However, since the retention loss of flash memory is the result of a mixture of multiple failure mechanisms, the Arrhenius model with a single apparent activation energy (Eaa) has significant limitations in calculating the high-temperature acceleration factor for the retention loss of flash memory. In this article, based on a large number of real experiments, we have studied the retention characteristics of the flash memory in high-temperature environments and closely tracked the change of Eaa at different temperatures, retention time, and program/erase (P/E) cycle count. The experimental results show that the equivalent acceleration factor (AF) grows rapidly with retention time at the beginning of flash retention and that flash with a high P/E cycle count has a faster AF growth rate.