Impact of failure criteria on electromigration of W-plug contact

This work presents an investigation of the impact of failure criteria on electromigration of a W-plug contact by using high resolution resistance measurement (HRRM). It is found that the median time to failure, T₅₀, linearly increases with an increasing failure criterion, while the shape parameter, σ, shows little change. The choice of failure criterion has a significant impact on the activation energy E_a calculated based on the resistance measurement. It has been demonstrated that this impact is an artificial result due to calculation without taking the ambient temperature dependent effects into account. The actual E_a is found to be 0.78 eV, independent of the failure criterion. It suggests that interfacial diffusion, rather than bulk diffusion, is a primary mechanism of bamboo structures in EM measurements