In the age of artificial intelligence, large language models (LLM) require rapid development along with massive volumes of training data and parameter storage. Over the past decade, 3D NAND flash memory has emerged as the dominant non-volatile memory technology due to its high bit density and large capacity. However, because of its 3D vertical stacking technique and array designs, 3D NAND flash memory has more complicated data loss mechanisms compared to 2D NAND flash memory. As bit densities rise to Quad-level-cells (QLC), the small read margins will further complicate and make the situation more unpredictable. In this work, we propose an error-bit prediction model in this paper for 3D QLC NAND flash memory with the charge-trap (CT) cell structure based on a thorough analysis of multiple parameters that affect the error-bit distributions, including read disturb (RD) and degradation from program/erase (PE) cycles. Specifically, we develop the whole-block prediction (WBP) and the dynamic-worst-page prediction (DWPM) models. It is shown that the proposed models can be used for high-precision error-bit prediction to guarantee data reliability in commonly used NAND-based storage systems based on the characterization results of raw NAND chips.

Three-dimensional (3D) NAND flash memory has become quite popular and is now widely used in data centers and mobile devices due to its outstanding storage density and cost-effectiveness. Larger storage capacity is made possible by 3D quad-level cell (QLC) NAND flash memory with the charge-trap (CT) structure, which stores four bits in each cell. However, data reliability is sacrificed in exchange for greater capacity. The lifespan of data retention is crucial for non-volatile storage. Thus, an important role is played by the Arrhenius model, which is widely used for lifespan prediction and high-temperature acceleration testing. Interestingly, we discover that the conventional Arrhenius model is inaccurate after analyzing the data retention properties of 3D QLC NAND flash memory. An empirical model is proposed for changing the apparent activation energy (Ea) based on the influence of different parameters, in order to accurately predict data lifespan and perform accelerated experiments. This developed model provides a temperature-and cycle-related parameter table for Ea, which is useful for high-temperature acceleration testing examinations. Simultaneously, we observe a linear connection between the 40∘C data retention time mapping and the other temperatures. We evaluate the effects of the modified Ea model and the classic Arrhenius model with the epitaxial data and conclude that the former can reduce the error by approximately 70% to a maximum.