Effect of Passivation and Mechanical Constraint on Electromigration in Interconnect

In this paper, we apply the Eshelby's solution to study the effect of passivation layer on electromigration (EM) failure in a conductor. The passivation layer is considered as an elastic material, not a rigid layer anymore. Thus, the deformation and stress evolution in the conductor during EM are related to the mechanical property of the passivation layer. One-dimensional (1D) analytical solution for the passivated conductor is obtained. The numerical results show that the conductor covered with the stiffer passivation layer has much less EM damage. And the steady-state solution shows that the magnitude of
$(\boldsymbol{jL})\mathbf{c}$
increases with increasing Young's modulus of passivation material. The present study provides a way to predict the EM performances taking into account various passivation materials.