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Reliability Physics of GaN HEMT Microwave Devices: The Age of Scaling

: Zanoni, E.; Meneghini, M.; Meneghesso, G.; Rampazzo, F.; Marcon, D.; Zhan, V.G.; Chiocchetta, F.; Graff, A.; Altmann, F.; Simon-Najasek, M.; Poppitz, D.


Institute of Electrical and Electronics Engineers -IEEE-:
IEEE International Reliability Physics Symposium, IRPS 2020. Proceedings : Grapevine, Texas, USA, 28 April - 30 May 2020, virtual symposium
Piscataway, NJ: IEEE, 2020
ISBN: 978-1-7281-3199-3
ISBN: 978-1-7281-3200-6
10 pp.
International Reliability Physics Symposium (IRPS) <58, 2020, Online>
Conference Paper
Fraunhofer IMWS ()

This paper reviews failure modes and mechanisms of 0.5 μm, 0.25 μm and 0.15 μm AlGaN/GaN HEMTs for microwave and millimeter-wave applications. Early devices adopting Ni/Pt/Au metallization were found to be affected by sidewall interdiffusion of Au and O, followed by electrochemical oxidation of AlGaN, a problem which was solved by adopting a new metallization and passivation scheme providing 0.25 μm devices capable of withstanding 24h at V DS = 60V, on-state, T ch = 375°C with no failure. 4000 h long-term thermal storage tests with no bias identified a non-monotonic behaviour of gate Schottky barrier height, causing a temporary increase of gate leakage current which presented no risk for device reliability. Beside contact-related degradation mechanisms, hot electron effects become increasingly more relevant during DC life tests (inducing a 10% increase of on-resistance), rf tests (creating or re-activating deep levels, which increase current-collapse and reduce rf output power and gain). RF tests are the harshest ones for hot-electron degradation, which represents the limiting factor for GaN HEMTs having L G ≤ 0.15 μm.