随着特征尺寸减小、单元多级和3D堆叠等技术的发展，当闪存芯片在密度提升、价格下降时，导致单元存储电荷数减少，单元和层间串扰加大，绝缘层性能变差，阈值电压变窄，数据存储可靠性下降，研究具有高纠错能力的纠错编码技术成为闪存系统设计的核心需求。本课题提出一种时空错误分布预测感知的变码率LDPC纠错编码和译码优化方案。主要研究内容：1）分析3D闪存错误属性特征，建立时空错误感知的数据失效模型；2）研究阈值电压漂移、状态跃迁量化规律。采用机器学习方法，建立多级单元状态跃迁概率模型和多维干扰与阈值电压漂移行为的关联关系模型；3）采用数据压缩和共享矩阵资源的策略，研究并构造时空错误分布预测感知的变码率LDPC纠错编码；4）研究基于数值相关性、错误率和电压感知的LDPC译码性能优化方法。本课题的研究可为解决采用3D闪存芯片的新一代存储系统在可靠性、性能优化等方面的问题提供新思路和关键核心技术。

With the scaling down of semiconductor process and the development of multi-level cell and 3D stacking technologies, the flash chips are experiencing a large increase in capacity and a rapid decline in price, while the quantity of electric charge per cell reduces, the inter-cell and inter-layer crosstalk increases, the performance of the insulating layer degrades and the threshold voltage distribution narrows down, leading to the decrease of data storage reliability, thus research on the error correction code technology with high error correction ability has become the core requirement of flash memory system design. This project proposes an optimization strategy for the encoding and decoding of space-time error distribution prediction-aware variable bit rate LDPC error correction. The main research contents are: 1) analyze the error characteristics of 3D NAND flash, and build a space-time perspective data failure model; 2) study the threshold voltage and state shift patterns, and employ machine learning methods to build a state transition probability model of multi-level cells and a relational model of multi-dimensional disturbs and the shift of threshold voltages of 3D NAND flash; 3) employ data compression and parity check matrix resource sharing strategy to study and construct a space-time error distribution prediction-aware variable bit rate LDPC error correction code; and 4) research on the performance optimization method of numerical correlation, bit error rate and voltage-aware LDPC decoding. The research of this project can provide key core technologies for effectively solving the reliability and performance problems in 3D flash memory system.