Mechanisms of power module source metal degradation during electro-thermal aging

R. Ruffilli, M. Berkani, P. Dupuy, S. Lefebvre, Y. Weber, M. Legros

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)


The long-term reliability of power devices for applications in the automotive industry is limited by the electro-thermal and/or thermo-mechanical aging of the metallic parts. In the present work, we characterize the bonding wire and source metallization degradation of power MOSFETs-based devices under accelerated aging conditions, through electron and ion microscopy. The metal degradation is driven by an enhanced self-diffusion of aluminium (Al) atoms along the grain boundaries and a generalized fatigue crack propagation from the surface down to the silicon (Si) bulk. The metallization under the wire bonds is a critical location because it is initially plastically deformed during the bonding process. In addition, the wire-metal interface presents several imperfections, such as small cavities and Al oxide residues. During the electro-thermal cycles, they could be the starting point for harmful cracks that run along the interface (and eventually cause the wire lift-off or the cracking of the substrate). Whichever the propagation direction, the generation of these cracks locally increases the device resistance and temperature, and accelerates the aging process until failure.

Original languageEnglish
Pages (from-to)507-511
Number of pages5
JournalMicroelectronics Reliability
Publication statusPublished - 1 Sep 2017
Externally publishedYes


  • Curvature experiment
  • Failure analysis
  • Focused Ion Beam (FIB)
  • Metallization microstructure aging
  • Power device
  • Scanning Electron Microscopy (SEM)
  • Temperature cycles

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics
  • Condensed Matter Physics
  • Safety, Risk, Reliability and Quality
  • Surfaces, Coatings and Films
  • Electrical and Electronic Engineering

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