三维电荷俘获存储器层间界面的多尺度理论研究：电子结构、输运性质及对器件可靠性的影响

3D-NAND memories are recognized as a representative candidate for the new generation of large-capacity flash memories, which have garnered a great deal of interest in recent years. However, the current understanding of the underlying mechanisms of 3D-NAND performances is still far from complete, and more thorough investigations into these issues are highly required. It is known that the interfaces of electronic devices represent an important factor impacting the device performance. In this Project, by focusing on several key interlayer interfaces of 3D-NAND charge-trap memories, we propose to perform an exploratory investigation on the interfacial properties of the devices by employing a multiscale modeling strategy. In particular, the proposed investigations include: 1) the studies of the geometric structures and the optimization of the interfacial morphologies, intrinsic defects, and doped defects by molecular dynamics simulations combined with first-principles calculations; 2) preliminary studies of the electronic properties including the trap-charge distributions, electronic potential distributions, energy levels, and band structures of the corresponding geometric structures by means of density functional theory calculations; 3) preliminary studies of the mapping of the charge-carrier distributions onto the grain boundaries and interfaces of the poly-Si channel by using a 3D Monte Carlo method, the calculations of the transport properties by means of non-equilibrium Green’s function theory, and the factors responsible for the device reliability. These proposed studies are important for enhancing our understanding of the underlying mechanisms of the device performances and instructive for optimizing the design of the materials and device structures in charge-trap 3D-NAND memories.

三维存储器（3D-NAND）是新一代大容量闪存的典型代表，近年来引起了高度重视，然而目前人们对其物理机制的理解还很不全面，亟待更加深入系统的研究。界面是影响电子器件性能的重要因素，本项目拟以电荷俘获型3D-NAND主要层间界面为研究对象，通过多尺度理论方法对器件界面性质进行探索性研究。具体包括：1）利用分子动力学结合第一性原理计算研究界面形貌、本征缺陷和掺杂缺陷的几何结构及其优化；2）通过密度泛函理论方法，初步研究相应结构下的电荷分布、电势分布、电子能级和能带结构等电子性质；3）通过三维蒙特卡罗方法和非平衡格林函数理论，初步研究多晶硅沟道晶界和界面处的载流子分布与输运性质以及对3D-NAND可靠性的影响。本项研究对深入理解三维电荷俘获存储器物理机制和优化材料和器件结构设计具有重要的指导意义。

界面是影响三维电荷俘获存储器及相关器件性能的重要因素。本项目以三维电荷俘获存储器及相关器件主要层间界面为研究对象，对界面处的形貌和缺陷的几何结构性质、电子结构性质、电输运性质、多晶硅沟道晶界性质以及器件可靠性等内容进行了研究，取得的研究进展如下：.（1）器件界面形貌和缺陷的几何结构、电子结构与电输运性质。通过构建多种界面结构，研究了不同形貌和缺陷条件下界面处的结构-性质关系，并提出了可能的材料和器件优化方案。.（2）多晶硅晶界性质。发展了构建原子尺度多晶硅晶界的方法，研究了其相关性质，并提出了改善多晶硅电输运性质的潜在方法。.（3）器件可靠性分析。揭示了影响器件可靠性的微观因素，并提出了可能的工艺优化策略。.这些研究对深入理解三维电荷俘获存储器及相关器件的物理机制及优化器件结构和材料设计具有积极的指导意义。