In-situ TEM study of electromigration in Cu lines

C. N. Liao, K. C. Chen, Wen-Wei Wu, L. J. Chen, King-Ning Tu

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Scopus citations

Abstract

The density of electric current passing through interconnecting wires in integrated circuits (IC) is increasing with continuous miniaturization of IC. Under a high operating temperature and large electric current density, some voids and hillocks may form in the interconnecting wires due to electromigration (EM), leading to device failures eventually. In this study atomic-scale EM in unpassivated copper lines has been investigated in ultrahigh vacuum by in situ transmission electron microscopy (TEM). The EM-induced atomic surface diffusion was found to be crystal-orientation dependent and occurred preferentially on the {111} planes along <110> directions. The high-resolution TEM images and the electron diffraction patterns of a (111)-oriented Cu grain in the Cu line revealed an EM-induced step structure at surface. Moreover, the triple point where a twin boundary meets a grain boundary was found to slow down atomic EM at grain boundaries because of the incubation time of nucleation of a new step at the triple point. The long incubation time slows down the overall rate of atomic transport. The results suggest that the EM reliability of Cu interconnects may be enhanced by forming a high density of nanometer scaled twins in the coarse-grain Cu wires.

Original languageEnglish
Title of host publicationStress-Induced Phenomena in Metallization - Tenth International Workshop on Stress-Induced Phenomena in Metallization
Pages12-19
Number of pages8
DOIs
StatePublished - 27 Nov 2009
Event10th International Workshop on Stress-Induced Phenomena in Metallization - Austin, TX, United States
Duration: 5 Nov 20087 Nov 2008

Publication series

NameAIP Conference Proceedings
Volume1143
ISSN (Print)0094-243X
ISSN (Electronic)1551-7616

Conference

Conference10th International Workshop on Stress-Induced Phenomena in Metallization
CountryUnited States
CityAustin, TX
Period5/11/087/11/08

Keywords

  • Electromigration, interconnects, diffusion, twin

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