Grain Boundary Crack Growth in Interconnects With an Electric Current

Published

June 1, 1999

Author(s)

C Y. Liu, S K. Lee, Tze J. Chuang

Abstract

Failure of thin-film interconnects poses a great concern in semiconductor devices. Due to the high electric current density in interconnects, electromigration-induced atomic flux is recognized as an important failure mechanisms. For wide polycrystalline interconnects, atomic flux along grain boundaries is believed to be the major failure mechanism. In situ transmission electron microscopy observations revealed void propagation along grain boundaries. Thus we consider steady state crack growth along a grain boundary in an interconnect subjected to a high current density. Crack growth occurs via mass transport driven by surface curvature and electric field. For crack propagation transverse to the remote electric field. For crack propagation transverse to the remote electric field, the direction of electric field on one crack surface is opposite to that on the other crack surface. The governing equation is derived and a numerical solution is presented. The results indicated that crack growth rate and width are proportional to E₀^3/2 and E₀^-1/2, respectively, where E₀ is the applied electric field. The crack tip morphology map can be divided into four regions for all materials with a known ratio of boundary to surface free energies: Case I is defined as that both crack-tip angles are positive, Case II, one of the crack angles is 0 , and Case III, one crack-tip angle is positive and the other is negative, Case IV, corresponds to that crack growth is physically impossible to occur.

Citation

Materials Science and Engineering B-Solid State Materials for Advanced Technology

Volume

B86

Pub Type

Journals

Keywords

aluminum wires, electric potential, electromigration, grain-boundary cracks, interconnects, mass transport, void growth

Citation

Liu, C. , Lee, S. and Chuang, T. (1999), Grain Boundary Crack Growth in Interconnects With an Electric Current, Materials Science and Engineering B-Solid State Materials for Advanced Technology (Accessed July 23, 2024)