Theory of Electromigration Failure in Polycrystalline Metal Films

多晶铝互连的电迁移失效是限制集成电路可靠性的主要失效机制之一。本研究将基于渗流理论对多晶金属薄膜的电迁移失效模型进行蒙特卡罗模拟和分析研究。研究了薄膜平均寿命和寿命分布与温度和结构无序程度的关系。工程应用中通常采用的膜寿命的经验分布将与蒙特卡罗结果进行比较，为这种分布提供比实验可能的故障率低得多的测试。本文将根据随机介质中不可逆过程理论的最新进展，建立失效动力学理论。随着时间的推移，这些思想将应用于非均匀脆性材料疲劳断裂的相关问题。随着集成电路变得越来越小，如何将这些电路内部的元件以及电路本身与外界连接起来的问题变得越来越关键。随着这些连接或互连变得越来越小，互连中发生电路故障的可能性就会增加。因此，了解潜在的机制和互连故障的概率对于预测设备的寿命是重要的。这项拨款采用了一种非常规的方法来研究这个难题。渗透理论从一般的角度来看待传导系统，如互连。它关注的不是潜在的物理细节，而是问题的更全面的方面。本文提出的研究将首次使用渗流理论来尝试预测互连寿命，并确定影响互连失效的一般参数。

Electromigration failure of polycrystalline aluminum interconnects is one of the primary failure mechanisms limiting the reliability of integrated circuits. In this research, Monte Carlo simulations and analytical studies will be made of a model of electromigration failure in polycrystalline metal thin films based on percolation theory. The dependence of the average film lifetime and the distributions of lifetimes on the temperature and degree of structural disorder will be investigated. An empirical distribution for the film lifetime which is commonly employed in engineering applications will be compared to the Monte Carlo results, providing a test of this distribution for much lower failure rates than is possible experimentally. A theory of the failure kinetics will be constructed which is based on recent advances in the theory of irreversible processes in random media. As time permits, these ideas will be applied to the related problem of fatigue-induced fracture in inhomogeneous brittle materials. %%% As integrated circuits become smaller and smaller, the problem of how to connect elements within these circuits, and the circuits themselves to the outside world, becomes more critical. As these connections, or interconnects, become smaller, the probability that circuit failure may occur in the interconnect increases. Thus, an understanding of the underlying mechanisms and of the probability for interconnect failure are important for predicting lifetimes of devices. This grant is using an unconventional approach to look at this difficult problem. Percolation theory looks at conducting systems such as interconnects from a general point of view. It is not as concerned about the underlying physical details as with the more global aspects of the problem. The research proposed here will use percolation theory for the first time to try to make predictions of interconnect lifetimes and determine general parameters which affect interconnect failure.