Fracture mechanism of LSI conductor due to atom migration induced by electri current and stress

众所周知，在大规模集成电路导体中，原子不仅受到电流的作用，而且还受到热应力的作用。相互作用的迁移导致空洞的产生，空洞的长大导致导体的失效。本研究获得的结果总结如下。(1)为了分析应力诱导迁移下空洞的生长，建立了沿着晶界扩散的有限元模型。模拟结果表明，沿导体-绝缘体界面的扩散沿着强烈地影响了原子的流动，改变了腔的生长速率。(2)从电流作用下原子沿表面沿着迁移的角度分析了腔的运动。(3)在上述结果的基础上，讨论了在相互作用下空穴增长的分析方法。该方法被移植到先进的有限元（1）中，使我们能够分析相互作用下多晶导体中的空穴生长。(4)在纯电流作用下，空穴的生长很小。但在空洞附近的晶界上产生了沿着的应力分布，空洞的生长受应力梯度引起的原子迁移控制。

It is well known that, atoms are transported by thermal stress as well as electric current in an LSI conductor. The interacted migration brings about cavities and the failure of conductor takes place by their growth. The results obtained from this study is summarized as follows. (1) An FEM of diffusion along grain boundaries is developed in order to analyze the cavity growth under the stress-induced migration. The simulation reveals that the diffusion along the interface between the conductor and the insulator strongly affects the atom flow and change the growth rate of cavity. (2) The movement of cavity is analyzed on the basis of atom migration along the surface due to electric current. (3) The analyzing method of cavity growth under interacted migration is discussed on the basis of the results (I) and (2). The method is implanted to the advanced FEM (1), which allows us to analyze the cavity growth in a polycrystalline conductor under the interaction. (4) The cavity grows little under migration induced by only electric current. However, it brings about the stress distribution along the grain boundaries near the cavity and the cavity growth is governed by the atom migration due to the stress gradient.