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Si-substrate removal for AlGaN/GaN devices on PCB carriers

: Reiner, Richard; Gerrer, Thomas; Weiss, Beatrix; Waltereit, Patrick; Mönch, Stefan; Meder, Dirk; Sinnwell, Matthias; Dammann, Michael; Quay, Rüdiger; Ambacher, Oliver


Institute of Electrical and Electronics Engineers -IEEE-; IEEE Electron Devices Society:
32nd International Symposium on Power Semiconductor Devices and ICs, ISPSD 2020. Proceedings : September 13-18, 2020, Vienna, Austria, Virtual Conference
Piscataway, NJ: IEEE, 2020
ISBN: 978-1-7281-4836-6
ISBN: 978-1-7281-4837-3
International Symposium on Power Semiconductor Devices and ICs (ISPSD) <32, 2020, Online>
Fraunhofer IAF ()
Si-removal; free-standing GaN; PCB-embedding; substrate engineering; back-gating; crosstalk suppression; capacitive coupling; thin film release; substrate biasing effect

This work presents a Si-substrate removal technique for AlGaN/GaN devices on PCB carriers. The Si-removal method is explained and experimentally applied to PCB embedded AlGaN/GaN-on-Si devices. The PCB-embedding package is reopened at the thermal pad by laser-removal and the Si-substrate is removed by wet chemical etching. The paper presents a direct comparison of the electrical characteristics for devices before and after Si-removal. Different substrate related effects are observed and investigated. The pulsed drain currents degrade after Si-removal, due to the absence of the thermal substrate capacitance. Furthermore, the dynamic on-state resistance is increased by surface trapping on the exposed backside. Measurement results are discussed and physically interpreted. The on-state resistance is unaffected in the range of 175 mΩ before and after Si-removal. The measurements show an increase of the off-state voltage from 600 V to 1400 V for devices after Si-removal.