Aluminum–germanium wafer bonding of (AlGaIn)N thin-film light-emitting diodes

Microsystem Technologies volume 19, pages 655–659 (2013)Cite this article

Abstract

Eutectic aluminum–germanium wafer bonding was used to fabricate (AlGaIn)N thin-film light-emitting diodes (LEDs). Wafer bonding was carried out on 2″ wafer level at a bond temperature of 470 °C using patterned Al bond pads on the GaN-on-sapphire LED epiwafer and plain Ge substrates. The microstructure of the joint formation was characterized via cross-section analysis using scanning electron microscopy and energy dispersive X-ray spectroscopy (EDX). Scanning acoustic microscopy was used to investigate the bond interface. The shear strength was determined to be 1–2 kN/cm2. The formation of a liquid Al–Ge phase is evident from cross-section analysis and optical microscopy. During solidification, Al and Ge are separated into distinct phases again, which is revealed by EDX. The obtained bond is not free of micro-voids, yet it is mechanically stable and suited for the fabrication of thin-film LEDs by removing the sapphire substrate via laser lift-off, which is also demonstrated.

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Acknowledgments

The authors would like to thank R.Schmidt, S. Müller and J. Wiegert for valuable contributions.

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Affiliations

  1. Fraunhofer Institute for Applied Solid State Physics, Tullastrasse 72, 79108, Freiburg, Germany

    Christian Goßler, Michael Kunzer, Rüdiger Moser, Thorsten Passow, Klaus Köhler, Ulrich T. Schwarz & Joachim Wagner

  2. Fraunhofer Institute for Electronic Nanosystems, Technologie-Campus 3, 09126, Chemnitz, Germany

    Mario Baum & Maik Wiemer

Authors
  1. Christian Goßler
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  2. Michael Kunzer
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  3. Mario Baum
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  4. Maik Wiemer
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  5. Rüdiger Moser
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  6. Thorsten Passow
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  7. Klaus Köhler
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  8. Ulrich T. Schwarz
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  9. Joachim Wagner
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Correspondence to Christian Goßler.

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Goßler, C., Kunzer, M., Baum, M. et al. Aluminum–germanium wafer bonding of (AlGaIn)N thin-film light-emitting diodes. Microsyst Technol 19, 655–659 (2013). https://doi.org/10.1007/s00542-012-1709-4

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Keywords

  • Wafer Bonding
  • Scanning Acoustic Microscopy
  • Eutectic Bonding
  • Electroluminescence Emission
  • Total Thickness Variation