Exploring the thermal limit of GaN power devices under extreme overload conditions

• Autores: F.P. Pribahsnik, M. Nelhiebel, M. Mataln, M. Bernardoni, G. Prechtl, F. Altmann, D. Poppitz, A. Lindemann
• Localización: Microelectronics reliability, ISSN 0026-2714, Nº. 76-77, 2017, págs. 304-308
• Idioma: inglés
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• Resumen

  • Abstract The performance of normally-off Gallium-Nitride (GaN) High-Electron-Mobility-Transistors (HEMTs) under extended short circuit operation is investigated. A thermal limit is found in the aluminium metallization, where at temperatures around 600 °C a protrusion of the gate metal through the Inter-Level Dielectric (ILD) may form, short-circuiting gate and source metallization and thus resulting in a permanently-off failure state. The present work shows how this particular failure mode can be induced by extreme overload operation, and presents a Finite Element (FE) model which agrees with the experimental observations and gives insights in the mechanical stress-state developing in the device. The deeper thermo-mechanical understanding of the degradation mechanism suggests directions in order to improve the device's robustness.