Characterization and monitoring structures for robustness against cyclic thermomechanical stress: Design and influence of Ti-Al(Cu) layer scheme

A wafer-level test approach based on dedicated test structures sensitive to repetitive-power-pulsing stress is described. The approach is suitable for the qualification of different IC backend stack options with respect to thermomechanical robustness in an early phase of technology development and for process control purposes. In this work, we investigate low-cycle robustness by end-of-life tests for different smart-power technologies with AlCu backend stack. Compared to reference trials a strong dependence of the mean lifetime on lower metal finger configuration and on the used Ti-Al(Cu) layer scheme is found.