Acoustic Emission Study of Electromigration Damage in Al-Cu Thin Film Conductor Stripes

Open-circuit as well as short-circuit failures can occur at regions where relief of electromigration-induced compressive stress is realized. These failures require that the restraining passivation layer surrounding the metal conductor gives way before either an extrusion or a void can form. This passivation layer is a sputtered SiO glass and is, consequently, quite brittle. Brittle materials do not yield, but rather deform via crack propagation. It is known that cracking of quartz results in an acoustic event that should be detectable with modern acoustic emission instruments.