Global and Local Characterization of Passivated Aluminum Metallization Film for Extracting Elastoplastic Constitutive Model

Plastic ratcheting of aluminum interconnects has been a major reliability concern for microelectronic devices. Various failure mechanisms associated with passivation and dielectric cracking during temperature cycling test have been attributed to this fundamental material response. Thus, understanding of the elastoplastic behavior of aluminum metallization gone through the actual process thermal history is crucial for ensuring back-end reliability. This article presents characterization of a passivated aluminum metallization film stack using Wafer Curvature and Spherical Nanoindentation to extract elastoplastic constitutive model parameters that reflect global (entire film) and local (point probe) aluminum material behaviors, respectively. Novel analytical-numerical approaches are proposed to systematically determine kinematic hardening models based on the responses of the composite dielectric-aluminum film stack. The ability to measure aluminum elastoplastic properties locally enables process monitoring on actual device wafers during development and production.