On the formation of voids in thin-film metal interconnects

A micromechanism of void formation, with emphasis on the kinetic process of void nucleation, in thin-film metal interconnects is proposed. The pre-existing debonded or weakly bonded area at the interface between the metal and the surrounding dielectric serves as the void initiation site. Numerical modeling of the evolving shear stress resolved on the slip systems during cooling from the fabrication temperature is performed. The resulting shear mode is used to construct a dislocation slip model. The mechanism of crystallographic slip is such that lateral thinning at the debond region, together with the slip step produced at the edges of debond lead to a net transport of atoms away from the debond and a physical void is thus formed.