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Evaluation Method of Delamination Strength at Interface Edge of Thin Films in Conductor of Advanced LSI

先进LSI导体薄膜界面边缘剥离强度评价方法

基本信息

批准号：
13555026
负责人：
KITAMURA Takayuki
金额：
$ 8.51万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2002
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-13555026/
关键词：
LSI Wiring Thin Film Microscopic Material Interface Interface Edge Delamination Strength 亀裂

项目摘要

Copper thin film is used for the conductor in advanced large-scale-integrated-circuits (LSI) in order to reduce electric resistance and to prevent fracture due to atom migration. A barrier layer is usually placed between the substrate and the film to prevent diffusion of copper atoms. The poor adhesiveness between them, however, sometimes causes interface fracture from the interface edge due to the free-edge effect. Although it is necessary to elucidate the mechanics of the delamination strength at the interface edge, no proper evaluation method has been proposed so far. In this study, an experimental method for the crack initiation is investigated based on the fracture mechanics concept. Especially, the focus is put on the stress singularity near the interface edge. In the experiment, the metal film is sandwiched by rigid substrate and beam so that the plastic deformation of film is constraint. Delamination tests are carried out by means of a loading apparatus, which is a modified Vickers hardness test machine. The experiments, the BEM (Boundary Element Method) analysis and MD (Molecular Dynamics) simulation reveal that the delamination criterion is successfully evaluated by the proposed method. The critical magnitude of the stress intensity factor, which governs the stress field near the edge, is examined for several film/substrate interfaces. Moreover, the crack initiation is governed not only by the external mechanical loading but also by the internal stress introduced in the fabrication process of the film, on the delamination. The experimental investigation shows that the superposition of both influence controls the crack initiation.

铜薄膜用于先进大规模集成电路（LSI）的导体，以降低电阻和防止原子迁移导致的断裂。在衬底和薄膜之间通常放置一层阻挡层以防止铜原子的扩散。但由于两者之间的粘结性较差，有时会由于自由边效应导致界面从界面边缘断裂。虽然有必要阐明界面边缘分层强度的机理，但目前还没有提出合适的评价方法。本文基于断裂力学的概念，研究了裂纹起裂的实验方法。重点研究了界面边缘附近的应力奇异性。在实验中，金属薄膜被刚性基材和梁夹在中间，使薄膜的塑性变形受到约束。分层试验是通过加载装置进行的，这是一种改进的维氏硬度试验机。实验、边界元法（BEM）分析和分子动力学（MD）模拟结果表明，该方法能够成功地评估分层判据。研究了几种薄膜/衬底界面的应力强度因子的临界大小，该因子控制着边缘附近的应力场。此外，裂纹的起裂不仅受外部机械载荷的影响，还受薄膜制造过程中引入的内应力和分层的影响。实验研究表明，这两种影响的叠加作用控制着裂纹的萌生。