The electromigration effect revisited: non-uniform local tensile stress-driven diffusion

Abstract The electromigration (EM) effect involves atomic diffusion of metals under current stressing. Recent theories of EM are based on the unbalanced electrostatic and electron-wind forces exerted on metal ions. However, none of these models have coupled the EM effect and lattice stability. Here,...

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Autores principales: Shih-kang Lin, Yu-chen Liu, Shang-Jui Chiu, Yen-Ting Liu, Hsin-Yi Lee
Formato: article
Lenguaje:EN
Publicado: Nature Portfolio 2017
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Q
Acceso en línea:https://doaj.org/article/e7e182a4b85c4c0994c957dfef0de697
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Sumario:Abstract The electromigration (EM) effect involves atomic diffusion of metals under current stressing. Recent theories of EM are based on the unbalanced electrostatic and electron-wind forces exerted on metal ions. However, none of these models have coupled the EM effect and lattice stability. Here, we performed in situ current-stressing experiments for pure Cu strips using synchrotron X-ray diffractometry and scanning electron microscopy and ab initio calculations based on density functional theory. An intrinsic and non-uniform lattice expansion – larger at the cathode and smaller at the anode, is identified induced by the flow of electrons. If this electron flow-induced strain is small, it causes an elastic deformation; while if it is larger than the yield point, diffusion as local stress relaxation will cause the formation of hillocks and voids as well as EM-induced failure. The fundamental driving force for the electromigration effect is elucidated and validated with experiments.