SHF: Small: Approximate-Computing Enabled Robust 3D NAND Flash Memories

传统的NAND闪存已经被广泛地用作基本上所有计算机系统的存储。增加NAND闪存容量，以满足当今不断增长的数据量的要求，已经通过技术扩展实现。然而，由于平面NAND电池的性能和可靠性下降，进一步的扩展已经戛然而止。因此，3D NAND闪存设计为连续密度增加开辟了一个新的方向，因为在不进一步缩小单元尺寸的情况下，可以通过在垂直方向上堆叠更多的单元来增加容量。然而，3D NAND由于其新的架构，在可靠性方面也面临着新的挑战。使用强纠错机制受到潜在的高功耗、实现面积和长操作延迟的限制。另一方面，有一种趋势是在计算和数据存储期间放宽数据准确性，因为今天的许多应用程序都可以容忍少量的错误。该项目旨在利用这种近似的数据存储来提高3D NAND闪存的可靠性、性能和耐用性。本研究将首先建立可靠性模型来指导建筑设计。然后，通过容错和近似编程实现近似存储的机制将被开发和评估。最后，将开发新技术来利用近似来减轻干扰，细胞间干扰，保留损失，以及提高3D闪存的性能和耐用性。该项目的成功将推动主流存储技术的持续扩展。它还将使3D NAND闪存广泛应用于嵌入式系统、个人电脑和云，这将对存储行业的创新产生巨大的推动作用。训练有素的学生将成为未来的任务，继续在计算技术创新。

Traditional NAND flash has been prevalently used as the storage for essentially all computer systems. Increasing the NAND flash capacity, to meet the requirement of today's ever increasing data volumes, has been enabled by technology scaling. However, further scaling has come to a screeching halt due to degraded performance and reliability in planar NAND cells. 3D NAND flash memory design thus opens a new direction for continuous density increase, as capacity can be multiplied by stacking more cells in vertical direction without further shrinking the cell sizes. Nonetheless, 3D NAND also faces new challenges in reliability due to its new architecture. Using strong error correction mechanisms is limited by potential high power consumption, implementation area and long operation latency. On the other hand, there is a trend in relaxing data accuracy during computing and data stores as many of today's applications are tolerant to a small amount of errors. This project aims to leverage such approximate storage of data to improve the reliability, performance and endurance of 3D NAND flash memories. The research will first construct reliability models to guide architecture designs. Then, mechanisms for achieving approximate storage through tolerating errors and approximate programming will be developed and evaluated. Finally, new techniques will be developed to exploit approximation for mitigating disturbance, cell-to-cell interference, retention loss, and for improving performance as well as endurance of a 3D flash memory. The success of this project will fuel the continuous scaling of the mainstream storage technology. It will also enable pervasive adoption of 3D NAND flash memories for embedded systems, personal computers and clouds, which will have a tremendous drive for the innovations in storage industry. Trained students will become future taskforce to continue technology innovations in computing.