EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

Repeated heat pulses can cause metallizations on substrates to suffer from gradual microstructural degradation. In this work a study on the thermo-mechanical fatigue behavior of electrochemically deposited (ECD) copper line structures on actively heated microchips is presented. In particular, a comparison between two different types of copper, corresponding to different electrolytes used for the electrodeposition process, is made. These two types of copper distinguish in grain size and in the amount of foreign atomic species incorporated. By means of the used microheaters, thermal loading conditions, characterized by sub-millisecond-short pulses with heating rates up to the order of 10⁶ K/s, are achieved. The fatigue tests are performed inside a scanning electron microscope. The specific in-situ setup used allows monitoring of the progressing surface degradation by means of periodical image acquisitions and, additionally, tracking the bulk-sensitive electrical resistance of the Cu line. Supporting roughness evaluations by means of confocal microscopy before and after the stress tests contribute to a more comprehensive and also quantitative characterization of the observed deformations.