A Theoretical Analysis of Electromigration Failure in Aluminum Interconnections

Electromigration was analyzed mathematically by solving Huntington's equation. A general solution assuming steady-state conditions was derived by Fourier transformation and complex integration. The analysis revealed that a significant accumulation of atoms at the anode induced hillock formation, and that atomic depletion at the cathode induced void formation. An electromigration acceleration test was performed to observe void formation using Al–0.5%Cu–1.0%Si on a SiO 2 /Si substrate. Experimental results of in situ observation were in good agreement with the theoretical result. The effect of a local stress field on void formation is discussed.