纳米部件中界面分层破坏的原位实验研究与数值分析

Since the nano-components in micro-electronic systems consist of dissimilar materials, the bi-material interface widely exists in these components. Deformation mismatch across the interface induces a concentrated stress field at the edge of interface, which is liable to cause the crack initiation at interface edge. Therefore, to assure the reliability of micro-systems, it is critically important to clearly investigate the crack initiation at the edge of interface in nano-component. In this project, the focus will be placed on the crack initiation at the edge of a typical copper/silicon (Cu/Si) interface in micro-systems, and a double nano-cantilever specimen including a transverse arm and a longitudinal arm will be proposed. By using this new specimen, experiments on the mode-Ⅰ, mode-Ⅱ and mixed-mode crack initiations at interface edge of nano-component are conducted, and crack initiation behaviors during loading process are in situ observed. In addition, on the basis of experimental results, the crack initiation behavior will be numerically simulated with a cohesive zone model (CZM), which reveals the mechanical mechanisms and influencing factors for crack initiation at interface edge. Moreover, the bonding strength of interface will be abstracted with CZM parameters, and the universal criterion for mode-Ⅰ, mode-Ⅱ and mixed-mode crack initiation will be achieved, which will supply experimental and theoretical supports for the reliability assessment and optimal design of micro-electronic systems.

微电子器件中的纳米部件通常包含大量双相材料界面，界面两侧材料的变形失配会在界面端部引起应力集中，使得界面端部极易发生启裂破坏。为了保证微系统的可靠性，亟需对纳米部件中界面端部裂纹启裂的行为开展深入研究。本项目拟针对微系统中典型的铜薄膜-硅基体系统，开发含有横纵双悬臂的新型纳米悬臂梁试样，开展纳米部件中界面端部Ⅰ型、Ⅱ型和复合型裂纹启裂的加载实验，并原位观测裂纹启裂的行为。在实验结果的基础上，采用内聚力模型对界面端部裂纹启裂行为进行模拟分析，揭示裂纹萌生的力学机制以及影响因素，提取由内聚力模型参数表征的界面强度指标，获得适用于Ⅰ型、Ⅱ型和复合型裂纹启裂的一般力学判据，为微电子器件的可靠性评估及优化设计提供实验支持和理论依据。

本项目对纳米部件中界面端部裂纹启裂的行为开展了深入研究。课题针对微系统中典型的铜薄膜-硅基体系统，开发了含有横纵双悬臂的新型纳米悬臂梁试样，开了展纳米部件中界面端部Ⅰ型、Ⅱ型和复合型裂纹启裂的加载实验。利用集成于透射电子显微镜样品杆前端的微小试样加载装置，在透射电子显微镜中对界面端部的裂纹启裂行为进行了原位观测。在实验结果的基础上，采用有限元法对界面端部的裂纹启裂行为进行了模拟分析，获得了裂纹启裂瞬时界面端部的临界应力分布状态。同时，利用内聚力模型模拟了界面端部的裂纹启裂过程，提取了由内聚力模型参数表征的界面强度指标，最终分别获得了由临界应力和内聚力参数表征的适用于纳米部件中界面Ⅰ型、Ⅱ型和复合型裂纹启裂的一般力学判据，研究结果为微电子器件的可靠性评估及优化设计提供了必要的实验支持和理论依据。